FIELD OF THE INVENTION The present invention relates to the fields of life sciences and medicine. Specifically, the invention relates to therapies of central nervous system defects. More specifically, the present invention relates to interleukin-13 (IL-13) for use in treatment or prevention of a central nervous system defect in a subject, wherein the central nervous system defect is selected from the group consisting of a cerebrovascular disease, spinal cord injury and spinal cord neurodegeneration. Still, the present invention relates to a method of treating or preventing a central nervous system defect in a subject and to a method of reducing lesion site or infarct volume or promoting motor function recovery of the central nervous system, wherein said methods comprise administration of IL-13 to a subject in need thereof.

BACKGROUND OF THE INVENTION

Central nervous system diseases or defects are a group of neurological disorders or defects that affect the structure or function of the spinal cord or brain. There are two broad classes of cells in the nervous system, neurons carrying nerve impulses and neuroglia providing the neurons with mechanical and metabolic support. When the function of a group of neural cells of the central nervous system is reduced or blocked or the neural cells die, symptoms of the subject may vary e.g. from mild headache to memory loss and paralysis.

Central nervous system defects include spinal cord injuries and spinal cord neurodegeneration and may be caused e.g. by cerebrovascular diseases. Few examples of said central nervous system defects affecting a large group of people and lacking effective therapy are described herein.

Stroke is the rapid loss of brain function due to a disturbance in the blood supply to the brain. Stroke is currently the second leading cause of death in the Western world, after heart disease and before cancer, causing -10% of deaths worldwide. Stroke can affect patients physically, mentally and emotionally, the extent of which is dependent upon the size and location of the lesion. Disability affects 75% of stroke patients enough to decrease their employability. Physical disabilities can include muscle weakness, numbness, speech and vision loss. Post-stroke emotional disabilities include anxiety, panic attacks, apathy and psychosis. Depression is also commonly reported, affecting 30-50% of stroke survivors.

Immediate treatment for stroke is dependent upon the cause (ischemic or hemor- rhagic) and may require surgery, for example, to remove a blood clot or to repair a bleed. To date, the only clinically approved therapies for stroke are mechanical endovascular thrombectomy or treatment with recombinant tissue plasminogen activator (tPA) and other drugs, such as dipyridamole and clopidogrel, may be used only in the secondary prevention of stroke in patients with previous history of is- chemic events. However, both mechanical thrombectory and tPA treatment must be provided within a limited timeframe after stroke onset and novel strategies are required for neuroprotection rather than clot dissolution. The major disadvantage of tPA therapy is the increased incidence of hemorrhagic transformation and thus only a fraction of patients, approximately 5% are suitable for receiving tPA therapy. Mechanical thrombectomy results in bleeding in 8-35% of the cases. Its use is limited to the largest hospitals and requires trained personnel that is rarely available in most of the units responsible for treating patients with acute stroke. Rehabilitation, to regain and relearn skills, is typically required by most stroke patients and usually involves a multidisciplinary team with activities such as physical, occupa- tional and speech therapy.

Spinal cord injury (SCI) is classified as damage to the spinal cord caused by trauma, instead of disease, with symptoms ranging from pain to paralysis to incontinence. Any injury that involves the head, pelvic fractures, penetrating injuries in the area of the spine or injuries that result due to a fall from height, may result in spinal cord damage. The most common causes of SCI are motor vehicle accidents, falls and violence.

In the US, there are an estimated 12,000 new cases of SCI each year, with ap- proximately 260,000 individuals afflicted by SCI. In Europe, there are estimated to be roughly 9,000 new SCI cases per year. Most incidences of SCI occur in people between the ages of 16-30 and hence healthcare expenses can be considerable, varying depending upon the severity of injury. Estimated lifetime costs for a tetra- plegic patient are greater than a $1 ,000,000. These figures do not include any indi- rect costs, such as losses in salary, which are estimated to be approximately $64,000 per year. Treatment options for SCI are extremely limited, with physical therapy a major treatment modality. Methylprednisolone, which helps to reduce swelling in the spinal cord, is widely prescribed as an off-label drug, but does not serve most pa- tients' needs. There are currently no therapies to alleviate, or repair, the incurred damage to the spinal cord.

Amyotrophic lateral sclerosis (ALS), also referred to as motor neuron disease and Lou Gehrig's disease, is the most common form of the motor neuron diseases. The disorder is characterised by rapidly progressive weakness, muscle atrophy, twitching and spasticity, difficulty with speaking and swallowing and a decline in breathing ability. The defining feature of ALS is the death of both upper and lower motor neurons in the motor cortex of the brain, the brain stem, and the spinal cord. The disease has its onset usually in midlife and leads to death within 3-5 years from diagnosis, usually due to respiratory failure. Once diagnosed, only 10% of patients survive for longer than 10 years. In the US, there are approximately 30,000 ALS sufferers, with 5,000 new cases each year.

There is no curative therapy for ALS and palliative care remains the most im- portant means of treatment. Riluzole is currently the only treatment found to improve survival, by 3-5 months, but patients do not report any subjective improvement. The mechanism of riluzole action is a matter of debate and was originally proposed to act as a sodium channel blocker, associated with damaged neurons, so reducing the influx of calcium ions and indirectly preventing the stimulation of glutamate receptors. However, no binding of riluzole to any receptor has been shown and its anti-glutamate action is still detectable in the presence of sodium channel blockers.

There remains a significant unmet need for effective and specific therapies delay- ing and alleviating the symptoms of diseases or injuries affecting the central nervous system.

BRIEF DESCRIPTION OF THE INVENTION The objects of the invention are achieved by utilizing a molecule with surprising effects on defects of the central nervous system. Said defects include but are not limited to (cerebro)vascular diseases of the brain and spinal cord, and injuries or neurodegenerative diseases of the spinal cord. It has now been found that IL-13 has a treating or preventive effect on subjects with a disease of the spinal cord caused by vascular defects, a neurological disease affecting the spinal cord or injury of the spinal cord. Also, it has now been found that IL-13 has a treating or pre- ventive effect on subjects with a disease of the brain caused by vascular defects either in the brain or affecting the brain. The present invention is based on the idea of providing IL-13 (e.g. an IL-13 polypeptide or any active fragment thereof) as a medicament for alleviating symptoms of patients or curing a disease caused by a vascular defect or a neurological disease affecting the brain or the spinal cord. The present invention makes it possible e.g. to reduce infarct volume, reduce the lesion site or promote motor function recovery. Indeed, the present invention solves the problems of conventional unsuccessful and unspecific therapies.

An object of the present invention is thus to provide a tool and a method for effec- tive and specific treatment or prevention of central nervous system disorders. Disorders or diseases of the brain or spinal cord may be caused e.g. by vascular defects. Disorders of the spinal cord include but are not limited to injuries and neurological diseases affecting the spinal cord (e.g. neurodegeneration). Disorders or diseases treated or prevented according to the present invention may involve neu- roinflammation (e.g. ALS or stroke).

IL-13 polypeptide is a natural molecule normally occurring in humans or animals. Induction of an immune reaction by IL-13 polypeptide provides a simple and safe way to achieve higher levels of therapeutic efficacy. The present invention reveals that IL-13 is effective against e.g. proinflammatory-driven diseases of the central nervous system. Even low dosages of IL-13 are enough to reach therapeutic efficacy. Medical intervention according to the present invention enables influencing simultaneously several of the pathogenic mechanisms. Furthermore, now it has been surprisingly found that IL-13 polypeptide is able to cross the blood-brain barrier and thus is effective in treating disorders of the central nervous system (e.g. a cerebrovascular disease, spinal cord injury or spinal cord neurodegeneration) also when administered systemically. Surprisingly IL-13 utilized according to the present invention has no side effects on a treated subject. The present invention relates to IL-13 for use in treatment or prevention of a central nervous system defect in a subject, wherein the central nervous system defect is selected from the group consisting of a cerebrovascular disease, spinal cord injury and spinal cord neurodegeneration.

Also, the present invention relates to a method of treating or preventing a central nervous system defect in a subject, wherein the central nervous system defect is selected from the group consisting of a cerebrovascular disease, spinal cord injury and spinal cord neurodegeneration, wherein the method comprises administration of IL-13 to the subject in need thereof.

Still, the present invention relates to a method of reducing lesion site or infarct volume or promoting motor function recovery of the central nervous system, wherein the method comprises administration of IL-13 to a subject in need thereof.

Other objects, details and advantages of the present invention will become apparent from the following drawings, detailed description and examples.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows the neuroprotective role of IL-13 in ischemic stroke. Infarct lesions were quantified from MRI images obtained 3 days post ischemia for control animals (n=7) and IL-13 treated animals (n=8). Analysis of infarct size revealed a significant reduction in infarct volume in IL-13 treated mice when compared to the control mice that received vehicle (PBS) only. Data are expressed as mean ± SEM. ^** p<0.01 .

Figure 2 shows MRI images of mice brain in control and IL-13 treated animals after three days post ischemic stroke. Infarct size revealed a significant reduction in infarct volume in IL-13 treated mice when compared to the control mice that received vehicle (PBS) only.

Figures 3A, 3B and 3C reveal that IL-13 was able to significantly upregulate argi- nine positive anti-inflammatory microglia/macrophage. In figure A the mice treated with IL-13 shows marked increase in Arg 1 immunoreactivity at 3 dpi. Figures B and C show representative images of brain sections treated with vehicle and IL-13 respectively. Data are expressed as mean ± SEM. ^* p<0.05. Figures 4A, 4B, 4C, 4D and 4E reveal that IL-13 treatment reduced stroke-induced astrogliosis. (A) Ischemia causes significant upregulation of astrocytic activation in the peri-ischemic area on ipsilateral side compared to contralateral side. IL-13 is able to reduce the activation toward significant level. Figures B and D represent GFAP immunoreactivity on the peri-ischemic area of control and IL-13 treated mice respectively and Figures C and E represent their contralateral side.

Figure 5 shows that IL-13 treatment promotes functional recovery after SCI. Hindlimb motor function was assessed by BMS at 1 , 7, 14, 21 and 28 days after SCI. The data are shown as mean ± standard error of mean, n = 7 for sham group, n=12 for vehicle group and n=10 for IL-13 group.

Figures 6A and 6B show the effect of IL-13 treatment on the lesion volume after white matter injury. Figure 6A shows a representative MRI picture of a focal lesion 7 days after L-NIO injection. Figure 6B shows a graph of the lesion volume in control group and group treated with IL-13 7 days after L-NIO injection. The data are shown as mean±SEM. n = 10. Figures 7A and 7B show the effect of IL-13 treatment on motor performance after white matter injury typical to vascular dementia. Graphs show the motor performance in baseline (Figure 7A) and in sham group, control group and group treated with IL-13 (Figure 7B) 3 days after L-NIO injection. The data are shown as mean±SEM. n = 10.

Figure 8 shows a SDS-page gel revealing that IL-13 inhibits LPS induced macrophage pro-inflammatory activation and promotes resolution in !ipopolysaccharide (LPS) stimulated macrophage in vitro inflammation model. DETAILED DESCRIPTION OF THE INVENTION

Cerebrovascular diseases, spinal cord injuries and spinal cord neurodegeneration

The central nervous system (CNS) is part of the nervous system and consists of the brain and spinal cord. Neurodegeneration is a term for the progressive loss of structure or function of neurons, including death of neurons. Neurons are present in the brain and spinal cord among others and therefore neurodegeneration may occur e.g. in the brain or spinal cord.

As used herein, "neuronal function" refers to any function of neurons including but not limited to neural connectivity. As used herein, "neural connectivity" refers to connections between neurons and interaction between neurons and glial cells. Neurons communicate with one another via synapses, where the axon terminal of one cell impinges upon another neuron's dendrite, soma or, less commonly, axon. Neurons can make connections even with tens of thousands of other cells. Synapses can be excitatory or inhibitory and either increase or decrease activity in the target neuron. Some neurons also communicate via electrical synapses, which are direct, electrically conductive junctions between cells. Improvement or restoration of neural connectivity alleviates symptoms of the degenerative disease in a patient.

Neurodegeneration means progressive loss of structure or function of neurons, including death of neurons. Neurons are the building blocks of the nervous system which includes the brain and spinal cord. Neurons normally don't reproduce or replace themselves, so when they become damaged or die they cannot be replaced by the body. Examples of spinal cord neurodegenerations include amyotrophic lateral sclerosis. Neurodegenerative diseases are incurable and debilitating conditions that result in progressive degeneration and/or death of nerve cells. This causes problems with movement (called ataxias), or mental functioning (called dementias). Many neurodegenerative diseases are caused by traumas directed at brain or spinal cord, or either hereditary or sporadic genetic mutations.

Neurodegeneration, either acute or slow and progressive dysfunction and loss of neurons and/or axons in the central nervous system, is the primary pathological feature of both acute and chronic neurodegenerative conditions. These diseases are also characterized by inflammatory responses, both innate and adaptive.

Inflammation is a defense reaction against diverse insults, designed to remove noxious agents and to inhibit their detrimental effects. It consists of molecular and cellular mechanisms and an intricate network of controls to keep them in check. In diseases affecting the central nervous system, inflammation may be triggered by the accumulation of aggregated or otherwise modified proteins, by signals emanating from injured neurons, or by imbalances between pro- and anti-inflammatory processes. Activation of the innate immune system is a crucial first line of defence, to opsonise and clear apoptotic cells. Furthermore, innate immune responses recruit cells of the adaptive immune system by secreting various cytokines and chemokines that induce adhesion molecules on the blood-brain barrier, and by inducing the expression of co-stimulatory molecules on microglia. Even though the initial aim of the immune activation is to protect the body from the initial insult, persistent inflammatory activation of the immune cells leads to neuronal damage.

As used herein, "a neurodegenerative disease involving neuroinflammation" refers to any neurodegenerative disease wherein innate and/or adaptive inflammatory response occurs. A neurodegenerative disease is either an acute or a chronic disease. Inflammation in neurodegenerative diseases is central or central and peripheral. In one embodiment of the invention a neurodegenerative disease involves both neuroinflammation and peripheral inflammation. As used herein, "neuroinflammation" refers to an activation of inflammatory mediator cells in the CNS. Pe- ripheral inflammation can be detected by alterations in blood cytokine levels and leukocyte responses.

As used herein, "a cerebrovascular disease involving neuroinflammation" refers to any cerebrovascular disease wherein innate and/or adaptive inflammatory re- sponse occurs.

As used herein, "an injury involving neuroinflammation" refers to any injury (e.g. injury of the spinal cord) wherein innate and/or adaptive inflammatory response occurs.

In one embodiment of the invention, a central nervous system defect, e.g. a cerebrovascular disease, spinal cord injury or spinal cord neurodegeneration, involves neuroinflammation. In another embodiment the central nervous system defect involves neuroinflammation and is selected from the group consisting of motor neu- ron diseases including subacute combined degeneration of spinal cord, amyotrophic lateral sclerosis (ALS), primary lateral sclerosis (PLS), progressive muscular atrophy (PMA), progressive bulbar palsy (PBP), pseudobulbar palsy and spinal muscular atrophies; spinal cord injury (SCI); cerebrovascular diseases including stroke caused by local brain or spinal cord ischemia, local brain or spinal cord hemorrhage, global ischemia caused by halted or drastically reduced blood flow to the whole brain, transient ischemic attack (TIA) or vascular dementia.

Macrophages are central players in the innate immune response following injury to CNS (David and Kroner, 201 1 , Nat Rev Neurosci 12(7): 388-399). Exposure of macrophages to type 1 helper T cell (Th1 ) cytokines such as interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-a) leads to their polarization to the M1 sub-population (the classical, pro-inflammatory macrophages), which is associated with cytotoxic processes (Gordon, 2003, Nat Rev Immunol 3(1 ): 23-35; Ma et al., 2003, Cell Mol Life Sci 60(1 1 ): 2334-2346; Kigerl et al., 2009, J Neurosci 29(43): 13435-13444; Busch et al., 2009, J Neurosci 29(32): 9967-9976; Cassetta et al., 201 1 , Scientific World Journal 1 1 : 2391 -2402; David and Kroner, 201 1 , Nat Rev Neurosci 12(7): 388-399; Shechter and Schwartz, 2013, J Pathol 229(2): 332- 346) and correlates with the severity of the disease progression and tissue damage in SCI (David and Kroner, 201 1 , Nat Rev Neurosci 12(7): 388-399). In contrast, the "alternatively activated" M2 macrophages demonstrate anti-inflammatory activities and are induced by type 2 helper T cell (Th2) cytokines such as interleu- kin (IL)-4, IL-10 and IL-13 (Gordon, 2003, Nat Rev Immunol 3(1 ): 23-35; Ma et al., 2003, Cell Mol Life Sci 60(1 1 ): 2334-2346; Cassetta et al., 201 1 , Scientific World Journal 1 1 : 2391 -2402; Shechter and Schwartz, 2013, J Pathol 229(2): 332-346). The M2 macrophages are essential in the amelioration of inflammation and facilitation of reparation after injuries such as SCI and stroke. Unfortunately, the micro- environment of the injured spinal cord and brain favors M1 polarization and the appearance of M2 macrophages remains transient (Kigerl et al., 2009, J Neurosci 29(43): 13435-13444; Schwartz, 2010, Brain Behav Immun 24(7): 1054-1057; David and Kroner, 201 1 , Nat Rev Neurosci 12(7): 388-399; Shin et al., 2013, Mol Neurobiol 47(3): 101 1-1019).

In contrast to M1 type, M2 macrophages are involved in the recovery of SCI (Schwartz, 2010, Brain Behav Immun 24(7): 1054-1057; David and Kroner, 201 1 , Nat Rev Neurosci 12(7): 388-399; Guerrero et al., 2012, J Neuroinflammation 9: 40-2094-9-40) and are required for oligodendrocyte differentiation and therefore remyelination. The role and contribution of M2-type inflammation in the context of stroke is very similar to SCI. M2-type macrophages protect neurons from ischemic isults (Fumagalli et al. 2013, Glia 61 (6): 827-42, Hu et al. 2012, Stroke 43(1 1 ): 3063-70) and promote markers related to enhanced neurogenesis (Pherson et al. 2014, Neurotox Res 25(1 ): 45-56).

The therapeutic effect of the majority of conventional neuroprotectants aims to halt the acute phase of brain diseases (stroke, SCI etc), which starts at the onset of the injury and lasts for a few hours. The limiting factor with targeting the acute phase is time, since especially in sparse inhabited areas the "symptom to needle" time is often too long. When the acute phase is resolved, that is days to weeks after embolism, important processes of neuroregeneration and repair begin.

For the treatment of brain or spinal cord defects or diseases IL13 enables effects including, but are not limited to, reducing lesion site or infarct volume or promoting motor function recovery of the central nervous system cell survival (e.g. neuron survival), alleviating secondary degeneration and a decrease in overall functional deficit, improving or restoring neuronal function or endogenous neuronal repair, cell survival (e.g. neuron survival), reducing harmful astrogliosis, or reducing harmful microglial activation. In one embodiment of the invention a lesion site or infarct volume is reduced or motor function recovery is promoted in the subject with a cerebrovascular disease, spinal cord injury or spinal cord neurodegeneration or in the subject after said disease, injury or neurodegeneration.

IL-13 based treatments of the present invention prevent neurodegeneration and improve regenerative processes during or after a central nervous system defect or disease or a specific phase thereof. IL-13 supports repair processes by inducing M2-shift in microglia activation. Indeed, IL-13 treatment enhances neuronal survival allowing brain cells suffering from ischemia or CNS trauma, directly or indirectly, to recover their original functions. Thus modification of the microenvironment of diseased brain or spinal cord to increase the number of M2 macrophages has beneficial effect through induction in pathways involved in neurorepair.

As used herein, "endogenous neuronal repair" refers to any mechanisms involved in demyelination, regulation of inflammation, axonal regeneration, neurogenesis, oligodendrogenesis, enhancement of neuronal function and health or restoration of neuronal connections and interaction between neurons and glial cells.

As used herein "reducing lesion site" refers to diminishing the size of the lesion. As used herein "reducing infarct volume" refers to diminishing the size of the infarcted area. As used herein "promoting motor function recovery" refers to improved movement.

As used herein "a defect" refers to any disorder or disease.

A vascular disease refers to a disease of the blood vessels i.e. the arteries and veins of the circulatory system of the body. A cerebrovascular disease is a vascular disease of the cerebral circulation. Arteries supplying oxygen and nutrients to the brain are affected resulting in one of a number of cerebrovascular diseases. In one embodiment of the invention cerebrovascular diseases may be selected from the group consisting of stroke caused by local brain or spinal cord ischemia, local brain or spinal cord hemorrhage, global ischemia caused by halted or drastically reduced blood flow to the whole brain, transient ischemic attack (TIA) and (cerebrovascular dementia. In one embodiment the cerebrovascular disease is select- ed from the group consisting of cerebrovascular dementia, global ischemia, focal ischemia, spinal cord infarct, transient ischemic attack and brain or spinal cord hemorrhage.

Stroke

Stroke is the rapid loss of brain function due to a disturbance in the blood supply to the brain or in the brain resulting in local injury of brain tissue. This may be caused by a blockage (ischemic stroke) or by a rupture to a blood vessel or an abnormal vasculature (hemorrhagic stroke). Approximately 87% of strokes are caused by is- chemia (ischemic stroke) and the remainder by hemorrhage (hemorrhagic stroke).

In one embodiment of the invention the stroke is an ischemic stroke. In another embodiment of the invention the stroke is a hemorrhagic stroke. Post-ischemic neuroinflammation, following stoke, promotes brain swelling that ultimately leads to compression of normal brain tissue surrounding the ischemic core and the exacerbation of neurological defects. Post-hemorrhagic neuroinflammation, following stroke, is also known to occur.

Infiltrating immune cells, such as leukocytes, together with injured brain cells, such as astrocytes, promote ischemic brain inflammation by producing various inflammatory mediators. Macrophages and neutrophils are pivotal players in the various processes of brain inflammation whilst T or B lymphocytes have also been reported to participate in delayed brain inflammation.

As a result of infiltrating immune cells, various cytokines and mediators are pro- duced. This includes IL-1 β and TNF-a, which are expressed in the ischemic brain within 30 min and 1 hr respectively following stroke onset. IL-1 β enhances the expression of chemokines in microglia and astrocytes whilst TNF-a can promote leukocyte infiltration and blood brain barrier breakdown. IL-6 is also expressed in ischemic brain tissue although its role has not yet been established. Consistent with the above, TNF-a, IL-1 and IL-6 are found to be elevated in CSF and blood, in humans, following ischemic stroke.

Global brain ischemia is defined by the rapid loss of brain function due to a disturbance in the blood supply in the brain. Global brain ischemia occurs when blood flow to the brain is halted or drastically reduced. This is commonly caused by cardiac arrest.

Brain hemorrhage Brain hemorrhage is bleeding in or around the brain and may follow e.g. an ischemic stroke or a significant blow to the head. Brain hemorrhage may be divided into four groups based on the location of the bleeding: subdural hemorrhage, extradural hemorrhage, subarachnoid hemorrhage, and intracerebral hemorrhage. Symptoms can include headache, one sided weakness, vomiting, seizures, de- creased level of consciousness, and neck stiffness. Often symptoms get worse over time.

Spinal cord hemorrhage Spinal cord hemorrhage is bleeding in or around the spinal cord. Hemorrhage affecting the spinal cord is rare. It most commonly is caused by trauma, vascular malformations or bleeding diatheses and can be intramedullary, subarachnoid, subdural or epidural.

Ischemia Ischemia is a vascular disease involving an interruption in the arterial blood supply to a tissue or organ and causing damage to or dysfunction of a tissue. Brain ischemia is insufficient blood flow to the brain or in the brain, and can be acute or chronic. This leads to poor oxygen supply or cerebral hypoxia and thus to the death of brain tissue or cerebral infarction/ischemic stroke. Ischemia or brain ischemia may be caused e.g. by embolism, thrombosis of an atherosclerosis artery or trauma. A brief episode of ischemia affecting the brain is called a transient ischemic attack (TIA) often called a mini-stroke. There are two types of brain ischemia: focal ischemia, which is confined to a specific region of the brain, and global ischemia, which encompasses whole or wide areas of brain tissue. The main symptoms involve impairments in vision, body movement, and speaking. The causes of brain ischemia vary from sickle cell anemia to congenital heart defects.

Ischemia may also occur in the spinal cord. Spinal cord ischemia with resulting paraplegia may be e.g. a devastating complication of thoracoabdominal aortic surgery. Vascular dementia

(Cerebro)vascular dementia is dementia caused by problems in the supply of blood to the brain leading to worsening cognitive decline that occurs step by step. People with vascular dementia have progressive cognitive impairment often after multiple cerebrovascular events (e.g. strokes). Other signs and symptoms are motor, behavioral and/or affective. These changes typically occur over a period of 5- 10 years. Signs are typically the same as in other dementias, but mainly include cognitive decline and memory impairment of sufficient severity as to interfere with activities of daily living, sometimes with presence of focal neurologic signs, and ev- idence of features consistent with cerebrovascular disease on brain imaging (CT or MRI).

Spinal cord infarct Spinal cord infarction is an occlusive vascular lesion affecting the spinal cord (spinal stroke). The anterior spinal artery is a single long anastomotic channel that lies at the mouth of the anterior central sulcus and supplies the circulation to the ante- rior two thirds of the spinal cord. It gives origin to sulcal arteries that take an arching course to one or the other anterior gray horns. The posterior spinal arteries are smaller paired arteries lying just medial to the dorsal roots. The arterial supply of the spinal cord arises from the aorta and at its cephalad and caudal ends from tributaries of the subclavian and iliac arteries. Eight to ten unpaired anterior medullary arteries are branches of the larger afferent aorta and vertebral and iliac arteries. The largest anterior medullary artery, the great anterior medullary artery of Adamkiewicz, is susceptible to occlusion with neurologic deficit. The risk to life and its quality from spinal cord infarction is substantial because of the disability, which can be severe, with paraplegia, risk of pulmonary emboli, and risk of infection (e.g. bladder, lungs, decubiti). However, no epidemiologic studies are available because of the relatively small number of patients affected. Spinal cord injury

SCI is classified as damage to the spinal cord caused by trauma, instead of disease, with symptoms ranging from pain to paralysis to incontinence. Any injury that involves the head, pelvic fractures, penetrating injuries in the area of the spine or injuries that result due to a fall from height, may result in spinal cord damage. The most common causes of SCI are motor vehicle accidents, falls and violence.

SCI is caused by both primary and secondary injury mechanisms. The former relates more specifically to the actual mechanical damage that occurs at the type of trauma, such as shearing, tearing and stretching of axons, neurons and blood vessels. The latter, proceeds over minutes, hours, days and even months after the initial traumatic insult and can lead to significant expansion of the original damage, causing paralysis to extend to further segments. These secondary mechanisms are a consequence of delayed biochemical, metabolic and cellular changes, which are initiated by the primary injury, and includes inflammation, free radical induced cell death and glutamate excitotoxicity (Chen et al, 2010, Indian J Med Res 135: 287-296). Neuroinflammation is a key component of secondary injury and plays a major role in regulating the pathogenesis of both acute and chronic SCI. Following SCI, central nervous system (CNS) inflammatory responses are initiated by both peripherally derived immune cells and activated glial cells that proliferate or migrate to the site of injury. Glial cells are major modulators of neuron viability and function. T cells play a crucial role in activating macrophages and mounting an immune response. Following access to the lesion site, lymphocytes can persist indefinitely, with T and B cell numbers shown to increase for at least 9 weeks in an SCI mouse model following trauma. Macrophages and microglia may participate in the inflammatory response through release of cytokines, such as TNF-a, IL-1 , IL-6, IL-10 and interferon, in addition to activation of specific interleukin receptors like IL-4R and IL-2R. Cytokine release can facilitate further CNS inflammatory responses by the induced expression of additional cytokines, chemokines, nitric oxide and reactive oxygen (Chen et al, 2010, Indian J Med Res 135: 287-296).

Spinal cord neurodegeneration

Spinal cord neurodegeneration refers to a disorder of the spinal cord, wherein the progressive loss of structure or function of neurons, e.g. death of neurons, takes place. Spinal cord neurodegeneration includes but is not limited to disorders such as subacute combined degeneration of spinal cord, amyotrophic lateral sclerosis (ALS), primary lateral sclerosis (PLS), progressive muscular atrophy (PMA), progressive bulbar palsy (PBP), pseudobulbar palsy and spinal muscular atrophies. In a specific embodiment of the invention the spinal cord neurodegeneration is se- lected from the group consisting of subacute combined degeneration of spinal cord, amyotrophic lateral sclerosis (ALS), primary lateral sclerosis (PLS), progressive muscular atrophy (PMA), progressive bulbar palsy (PBP), pseudobulbar palsy and spinal muscular atrophies. Subacute combined degeneration of spinal cord, also known as Lichtheim's disease, refers to degeneration of the posterior and lateral columns of the spinal cord as a result of vitamin Bi ₂ deficiency, vitamin E deficiency, and copper deficiency. Symptoms include e.g. abnormal sensations and weakness of the legs, arms, or other areas. These symptoms slowly get worse and are usually felt on both sides of the body. As the disease worsens, symptoms may include e.g. clumsiness, stiff or awkward movements, change in mental state, (such as memory problems, irritability, apathy, confusion, or dementia), decreased vision.

Primary lateral sclerosis (PLS) is a rare neuromuscular disease characterized by progressive muscle weakness in the voluntary muscles. PLS belongs to a group of disorders known as motor neuron diseases. Motor neuron diseases develop when the nerve cells that control voluntary muscle movement degenerate and die, caus- ing weakness in the muscles they control. PLS only affects upper motor neurons i.e. motor neurons that originate either in the motor region of the cerebral cortex or in the brain stem and carry motor information down to the lower motor neurons. Progressive muscular atrophy (PMA) a rare subtype of motor neuron disease that affects only the lower motor neurons i.e. motor neurons located in either the anterior grey column, anterior nerve roots (spinal lower motor neurons) or the cranial nerve nuclei of the brainstem and cranial nerves with motor function (cranial nerve lower motor neurons).

Progressive bulbar palsy (PBP) is a disease that attacks the nerves supplying the bulbar muscles.

Pseudobulbar palsy is characterized by the inability to control facial movements (such as chewing and speaking) and caused by a variety of neurological disorders. Patients experience difficulty chewing and swallowing, have increased reflexes and spasticity in tongue and the bulbar region, and demonstrate slurred speech, sometimes also demonstrating uncontrolled emotional outbursts. Spinal muscular atrophies is a group of rare debilitating disorders characterized by the degeneration of lower motor neurons and subsequent atrophy of various muscle groups in the body.

In one embodiment of the invention the spinal cord neurodegeneration is amyo- trophic lateral sclerosis.

Amyotrophic lateral sclerosis

ALS, also referred to as motor neuron disease and Lou Gehrig's disease, is the most common form of the motor neuron diseases. The disorder is characterised by rapidly progressive weakness, muscle atrophy, twitching and spasticity, difficulty with speaking and swallowing and a decline in breathing ability. The defining feature of ALS is the death of both upper and lower motor neurons in the motor cortex of the brain, the brain stem, and the spinal cord.

The majority of ALS cases are sporadic (sALS), meaning they occur without an inherited cause, and approximately 10% of cases are familial (fALS). The etiology of ALS is not clearly defined and hence the exact pathway to trigger the disease has remained obscure, complicating the development of efficient treatment. fALS cases have heterogenous genetic background and are caused by mutations in a range of genes. The most commonly affected genes include C9ORF72, SOD1 , FUS/TLS, and TARDBP. In addition to the complex background, the pathophysiological mechanisms in ALS are various and not completely understood. Glutamate excitotoxicity, mitochondrial dysfunction, oxidative stress and neuroinflammation are among the pathogenic cellular mechanisms that contribute to the neurodegen- eration in ALS. The complexity of the disease is probably the underlying reason why development of treatments that could slow down the disease progression, or stop it, has been unsuccessful.

C9orf72 mutations are present in approximately 40% of familial ALS and 8-10 % of sporadic ALS. It is currently the most common demonstrated mutation related to ALS. Even though the mutations are known to interfere with normal expression of the protein made by C9orf72, the function of that protein is unknown. One theory suggests that C9orf72-associated accumulation of RNA in the nucleus and cytoplasm becomes toxic resulting in sequestration of RNA binding protein. The other is that the lack of half of the C9ORF72 protein (haploinsufficiency) in the body causes the diseases. Moreover, RNA transcribed from the C9ORF72 gene, containing expanded GGGGCC repeats, is translated through a non-ATG initiated mechanism. This may drive the formation and accumulation of dipeptide repeat proteins corresponding multiple ribosomal reading frames on the mutation. GGGGCC repeat expansion in C9orf72 then may compromise nucleocytoplasmic transport.

One of the most commonly mutated genes causing fALS is SOD1 (superoxide dismutase, a free radical scavenging enzyme), which accounts for 20% of cases. In addition, mutated SOD1 (mSOD7) has been identified in 1 -3% of sALS cases. In 1993 the identification of mutated SOD1 as a cause for fALS, revolutionized the genetic research of ALS. From then, the list of known SOD1 mutations has expanded and in current knowledge there are almost 170 ALS-associated mutations in SOD1 at approximately 70 of the 153 amino acids, which are widely distributed throughout the gene.

The mechanism by which mutated SOD1 causes cellular toxicity and ALS is not fully understood. After identifying the connection between SOD1 mutations and fALS it was suggested by many researchers that disease onset was likely due to increased or decreased enzyme activity. These hypotheses were soon rejected due to the significant number of mutations distributed throughout the gene rather than localized to the active site. Secondly, it was discovered that the cause is not a loss of function, but rather a gain of toxic property, which is not dependent on SOD1 activity or aberrant protein aggregation. The loss of function theory is further disproved by mice that lack SOD1 gene and do not develop motoneuron disease. More importantly, several ALS patients with mSOD1 have normal levels of SOD1 activity.

Neuroinflammation is a hallmark of ALS and it manifests as activation of microglia and astrocytes in the CNS and is complimented by the involvement of peripheral immune cells. Astrocytes modulate synaptic transmission by regulating availability of several neurotransmitters and protect neurons from oxidative stress. Microglia are the immune effector cells of the CNS and depending on the surrounding factors they can be activated to anti- or proinflammatory direction. Both astrocytes and microglia can secrete neurotrophic factors to promote neuronal survival or under stress they can produce proinflammatory cytokines and other factors that are neurotoxic.

Involvement of inflammation in the CNS pathology of ALS is demonstrated by the activation and proliferation of microglia and infiltration of CD4 and CD8 T-cells and dendritic cells into the spinal cords of ALS patients and transgenic mSOD1 mice. Moreover, mSOD1 expressing astrocytes are prone to exhibit an activated pro- inflammatory state, proposing an elevated inflammatory status in ALS. In the CSF of ALS patients there are elevated levels of IL-6, monocyte chemoattractant pro- tein-1 , and IL-8, whereas in postmortem spinal cord samples pro-inflammatory prostaglandin E2 and cyclooxygenase-2 (Cox-2, an enzyme synthesizing inflammatory prostanoids) are elevated. Pro-inflammatory cytokines IL-1 a, IL-I β, and tumor necrosis factor-a (TNF-a), in addition to Cox-2, are increased in mSOD1 mouse spinal cord. The immune response is also activated in the blood of ALS patients, where there is a reduction in regulatory T cells and monocytes already during the early stages of disease. lnterleukin-13

IL-13 is a cytokine and an important modulator of peripheral allergic reactions. IL- 13 is produced primarily by T-helper type 2 lymphocytes and is considered as an anti-inflammatory cytokine because it can downregulate the synthesis of T-helper type 1 pro-inflammatory cytokines. It has been found that microglial cells and possibly neurons produce IL-13 molecules. (Mori et al. Brain Sci 2016, 6, 18 doi:10.3390/brainsci6020018)

In the study of Kawahara et al. (Neuroscience 2012, 207, pages 243-260) the combination of IL-13 and IL-4 was able to show protection in a mouse model of Alzheimer's disease. Specifically, intracerebral injection of a mixture of IL-13 and IL-4 reduced amyloid deposition and improved spatial learning and memory in an AD transgenic mouse model when applied to young mice but did not show protective effects when administered in adult animals.

As used herein, the term "IL-13" refers to a full-length IL-13 polypeptide or any fragment thereof having IL-13 biological activity, or to a polynucleotide encoding said full-length IL-13 polypeptide or encoding any fragment of the IL-13 polypeptide having IL-13 biological activity.

It is evident to a person skilled in the art that the IL-13 polypeptide to be used in accordance with the present invention includes any variants as long as it retains its biological activity. An exemplary way of determining whether or not an IL-13 polypeptide or any fragment thereof has maintained its biological activity is to determine its ability to bind its canonical receptor alpha type I (IL-13Ra1 ) according to any method well known in the art, e.g. by measuring IL-13 induced STAT6 phos- phorylation in IL-13Ra1 transfected cells as described in Kasaian MT et al . (2014, Immunology 143(3):416-27).

The IL-13 polypeptides or fragments thereof may be either naturally occurring or modified (e.g. recombinant) polypeptides. In one embodiment the polypeptides are purified.

As used herein, the term "IL-13 polynucleotide" refers to any polynucleotide, such as single or double-stranded DNA or RNA, comprising a nucleic acid sequence encoding an IL-13 polypeptide or any biologically active fragment thereof. Multiple IL-13 encoding polynucleotide sequences exist and any of them may be used in accordance with the present invention as long as it encodes an IL-13 polypeptide that has retained its biological activity. An IL-13 polynucleotide may also comprise a suitable promoter and/or enhancer sequence for expression in the target cells, said sequence being operatively linked upstream of the coding sequence. If desired, the promoter may be an inducible promoter or a cell type specific promoter. Suitable promoter and/or enhancer sequences are readily available in the art and include, but are not limited to adeno- associated virus type 2 and type 5 vectors, capsid-mod if ied AAV6 vectors or CD68 promoter in lentivirus vector. Polynucleotides encoding IL-13 or a fragment thereof may be targeted into selected target cells or tissues in a manner that enables expression thereof in a therapeutically effective amount. In accordance with the present invention, gene therapy may be used in a therapeutically effective amount in a subject with neurodegenerative disease involving neuroinflammation. IL-13 polynucleotides de- scribed above may be applied in the form of recombinant DNA, plasmids, or viral vectors. Methods of delivering polynucleotides are available in the art. IL-13 polynucleotides may be delivered as naked polynucleotides or incorporated into a viral vector under a suitable expression control sequence. Suitable viral vectors are readily available in the art and include, but are not limited to, retroviral vectors, such as lentivirus vectors, adeno-associated viral vectors, and adenoviral vectors. According to some embodiments a vector cannot replicate in a mammalian subject.

Mouse IL-13 is known to have e.g. gene ID number 16163 (Mus musculus) and human IL-13 is known to have e.g. gene ID number 3596 (Homo sapiens).

As used herein "a fragment" refers to any part of IL-13 having a therapeutic effect. In one embodiment of the invention the fragment has a function of IL-13. In one embodiment the function of IL-13 is to improve the body's response to a disease.

In one embodiment of the invention IL-13 is an IL-13 polypeptide or a combination of an IL-13 polypeptide and a polynucleotide encoding an IL-13 polypeptide. In a further embodiment IL-13 is an IL-13 polypeptide and the cerebrovascular disease is selected from the group consisting of cerebrovascular dementia, ischemia, focal ischemia, spinal cord infarct, cerebral stroke, stroke and brain hemorrhage. In a still further embodiment IL-13 is an IL-13 polypeptide and the spinal cord injury or spinal cord neurodegeneration is selected from the group consisting of an amyo- trophic lateral sclerosis and spinal cord injury. In a specific embodiment IL-13 is a polynucleotide encoding an IL-13 polypeptide or a combination of a polynucleotide encoding an IL-13 polypeptide and an IL-13 polypeptide. In one embodiment of the invention, IL-13 polypeptide, a fragment thereof, a polynucleotide encoding for IL-13 polypeptide or a fragment thereof is of a human origin, a mouse origin, a rodent origin, or any combination thereof, such as a human- mouse, human-rodent, mouse-rodent, human-mouse-rodent combination. Most preferably IL-13 polypeptide, a fragment thereof, a polynucleotide encoding for IL-13 polypeptide or a fragment thereof is of a human or mouse origin. In a further embodiment of the invention IL-13 is a recombinant IL-13 polypeptide, a recombinant fragment thereof, a recombinant polynucleotide encoding for IL-13 polypeptide or a recombinant fragment thereof. It is possible to use a human, non- human or recombinant IL-13 polypeptide or polynucleotide encoding IL-13 for a human patient or a human, non-human or recombinant IL-13 polypeptide or polynucleotide encoding IL-13 for an animal.

Pharmaceutical composition and administration According to the present invention IL-13 can be used for the manufacture of a medicament for treatment or prevention of a CNS defect.

As used herein, the term "treatment" or "treating" refers to administration of at least IL-13 to a subject, preferably a mammal or human subject, for purposes which include not only complete cure but also amelioration or alleviation of disorders or symptoms related to a degenerative disease in question. Therapeutically effective amount of IL-13 refers to an amount with which the harmful effects of a CNS defect are, at a minimum, ameliorated. The harmful effects of a CNS defect include but are not limited to muscle weakness, muscle atrophy, twitching, spastic- ity, difficulty with speaking and swallowing, speech and vision loss, decline in breathing ability, numbness, anxiety, panic attacks, apathy, psychosis, depression, pain, paralysis or incontinence, as well as difficulties with memory, concentration, communication, language, reasoning, judgement or visual perception. The effects of IL-13 may be either short term or long term effects.

According to the present invention IL-13 is administered to a subject as a pharmaceutical composition. A pharmaceutical composition of the invention comprises at least IL-13 polypeptide, a fragment thereof, a polynucleotide encoding IL-13 or a fragment thereof. In addition a pharmaceutical composition may also comprise any other therapeutically effective agents, any other agents, such as a pharmaceutically acceptable solvent, diluent, carrier, buffer, excipient, adjuvant, antiseptic, filling, stabilising or thickening agent, and/or any components normally found in corresponding products.

The pharmaceutical composition may be in any form, such as in a solid, semisolid or liquid form, suitable for administration. A formulation can be selected from a group consisting of, but not limited to, solutions, emulsions, suspensions, tablets, pellets and capsules.

The pharmaceutical compositions may be produced by any conventional processes known in the art.

Amounts and regimens for therapeutic administration of IL-13, a fragment thereof, a polynucleotide encoding IL-13 or a fragment thereof can be determined readily by those skilled in the clinical art of treating CNS defects or diseases. Generally, the dosage of the IL-13, a fragment thereof, a polynucleotide encoding IL-13 or a fragment thereof varies depending on multiple factors such as age, gender, other possible treatments, neurodegenerative disease in question and severity of the symptoms. For administration of IL-13 polypeptide or a fragment thereof a typical dose is in the range of 0.001 to 50 mg/kg, more specifically in the range of 0.01 to 20 mg/kg or 0.01 to 10 mg/kg, most specifically 0.03 to 1 mg/kg. For instance, when viral vectors are to be used for gene or polynucleotide delivery, the vector is typically administered, optionally in a pharmaceutically acceptable carrier, in an amount of 10 ⁷ to 10 ¹³ viral particles, preferably in an amount of at least 10 ⁹ or at least 10 ¹⁰ viral particles. The present invention is utilized for use in treatment or prevention of a CNS defect in a subject.

In one embodiment of the invention a subject is a human or an animal, a child, an adolescent or an adult. A subject is in need of a treatment or prevention of a neurodegenerative disease with IL-13. Most preferably a subject is a human patient suffering from a CNS defect selected from the group consisting of a cerebrovascu- lar disease, spinal cord injury and spinal cord neurodegeneration. Also any animal, such as a pet, domestic animal or production animal, suffering from a CNS defect or disorder may be a subject of the present invention. Before classifying a subject as suitable for the therapy of the present invention, the clinician may for example study any symptoms or assay any disease markers of the subject. Based on the results deviating from the normal, the clinician may sug- gest IL-13 based treatment of the present invention for the subject.

Any conventional method may be used for administration of IL-13 polypeptide, a polynucleotide or fragments thereof or a pharmaceutical composition to a subject. The route of administration depends on the formulation or form of the composition, the disease, the patient, and other factors. In one embodiment of the invention, the administration is conducted through an intramuscular, intra-arterial, intravenous, intracavitary, intracranial or intraperitoneal injection, or an oral administration. In one embodiment of the invention IL-13 is administered systemically. Additionally, the administration of the IL-13 can be combined to the administration of other therapeutic agents. The administration can be simultaneous, separate or sequential. The administration of IL-13 can also be combined to other forms of therapy, such as surgery, and may be more effective than either one alone. In one embodiment of the invention IL-13 is utilized as the only therapeutically active agent.

A desired dosage can be administered in one or more doses at suitable intervals to obtain the desired results. Only one administration of IL-13 may have therapeutic effects, but specific embodiments of the invention require several administra- tions during the treatment period. For example, administration may take place from 1 to 30 times, 1 to 20 times, 1 to 10 times, two to eight times or two to five times in the first 2 weeks, 4 weeks, monthly or during the treatment period. The length of the treatment period may vary, and may, for example, last from a single administration to 1 -12 months, two to five years or even more.

Any method or use of the invention may be executed either in vivo, ex vivo or in vitro.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described below but may vary within the scope of the claims. EXAMPLES

Example 1 : IL13 is protective in a mouse model of stroke

Material and Methods

Animals:

All the animal experiments were approved by National Animal Experiment board of Finland and followed the Council of Europe Legislation and Regulation for Animal Protection. Approximately 4 months old Balb/cOlaHsd mice were divided into Control (n=8) and IL-13 treated (n=10) group. Three animals (control n=2) and IL-13 treated (n=1 ) were excluded from the study due to missed bifurcation. Ischemia surgery and treatment:

Animals were anesthetized with 5% isoflurane and maintained with 2% isoflurane (70%N20/30% 02). Body temperature was maintained at 36.5 ± 0.5°C using a thermostatically controlled rectal probe connected to a homeothermic blanket during surgery. Middle cerebral artery was permanently coagulated using a thermo- coagulator. Briefly, temporalis muscle was retracted and temporal bone was exposed by making a small incision between eye and ear. A small hole of approximately 1 mm diameter was drilled above MCA and dura was removed. Following the removal of dura, MCA was lifted and cauterized, the muscle was replaced and skin wound sutured. After recovery from anesthesia, Animal received either PBS (volume 10Oul) or IL-13 (mouse recombinant, R&D systems, 1 ug/animal; Volume 10Oul) intravenously through tail vein and returned to normal cages. The mice were then terminally anesthetized with 250mg/kg Avertin and perfused at day 3 post ischemia. Magnetic Resonance imaging:

Magnetic resonance imaging (MRI) was performed 3 day post ischemia using 9.4T Oxford NMR magnet. Multislice T2 weight images (repetition time 3000ms, echo time 40ms, matrix size 128 ^* 256 and Field of view 19.2 ^* 19.2 mm2, slice thickness 0.8mm and number of slices 12) were obtained using double spin-echo sequence with adiabatic refocusing pulse. The image was then analyzed using in-house made Aedes software under Matlab environment. The relative percentage of infarction volume was calculated using the formula Infarct volume= (volume of left hemisphere- (volume of right hemisphere- measured infarct volume))/volume of left hemisphere.

Immunohistochemistry:

Animal were sacrificed 3-day post ischemia. Brains were removed and fixed in 4% PFA for 18-20 h followed by cryopreservation in 30% sucrose for 48 h. The brains were frozen in liquid nitrogen and cut into 20μΜ thickness using cryostat. Total of six consecutive sections that are 400μΜ apart were taken for analysis from each animal. Brain astrogliosis was visualized using glial fibrillary acid protein (GFAP) and M2-type microglia were visualized using Arginase-1 staining. The brain sections were incubated with primary antibodies (GFAP, 1 :500, DAKO, Denmark; Ar- ginase 1 , 1 :200, Santa Cruz Biotechnology, TX, USA) overnight at room temperature. For arginase staining, the sections underwent antigen retrieval in 0.3% sodium citrate dehydrate preheated to 92°C and pH 6. Following overnight incubation, the sections were washed with phosphate buffered saline containing 0.05% tween 20 and reacted against secondary antibody (Alexa flour 568 for both staining). To determine GFAP immunoreactivity, an area of 718*532μΜ was imaged in the peri- ischemic area right adjacent to infarct border on 10x magnification using AX70 microscope. In addition, a corresponding area on the contralateral side was also analysed. For arginase, area of same size was taken in the lesion area. Both GFAP and arginase staining were analysed from a total of 15 animals (Control, n =7 and IL-13, n=8).

Results

Neuroprotection

To elucidate the neuroprotective role of IL-13 in ischemic stroke, mice received either 10Oul of PBS (control group) or IL-13 at a dose of 1 ug/animal (treated group) right after ischemia induction. MRI was performed in mice brain after three days post ischemia and lesion size determined. Analysis of infarct size revealed a significant reduction in infarct volume in IL-13 treated mice when compared to the control mice that received vehicle (PBS) only (Figures 1 and 2). Increased anti-inflammatory M2-type microglia/macrophage in the lesion Microglia being main resident immune-competent cells in the brain, we used im- munohistochemistry to investigate whether the protective effect observed in lesion area is associated with phenotypic shift of microglia/macrophage from proinflammatory (M1 ) to anti-inflammatory (M2). Indeed, IL-13 treatment was able to significantly increase the amount of M2 type microglia following ischemic stroke in the ipsilateral hemisphere (Figures 3A-C).

As expected, ischemic stroke significantly upregulate astrocytic activation in peri- ischemic on the ipsilateral side of both treatment groups when compared to con- tralateral side. Moreover, the extent of astrocyte activation was reduced upon IL- 13 treatment following ischemic stroke was higher in the control group than the IL- 13 treated group (Figures 4A-E).

Example 2. IL-13 protects against spinal cord injury

Materials and Methods

Animals:

All experimental procedures were approved by the Animal Experiment Committee in State Provincial Office of Southern Finland and conducted according to the national regulation of the usage and welfare of laboratory animals. Adult 3 month old female C57BL/6J mice were used in this study. Animals were housed in groups of three to five in cages under 12-hour light/dark cycle with water and standard food provided ad libitum. Additional water and powdered food was made available for the first 7 days after SCI.

Surgery procedure and spinal cord injury:

The mice were anesthetized as described in Pomeshchik et al. (2015 Brain Behav Immun. 44, 68-81 ). A clinically relevant moderate contusion SCI (60 kDynes force) was performed at T10 level using an Infinite Horizons Impactor (Precision Scientific Instrumentation, Lexington, KY) as described in Pomeshchik et al. (2015 Brain Behav Immun. 44, 68-81 ). For analgesia buprenorfine (Temgesic®, Schering- Plough, Belgium) 0.1 mg/kg waa injected subcutaneously 30 min before surgery and then same dosage every 12 h for 3 days. The mice were kept on 37 °C heat- ing pads for three days after surgery. The bladder was manually expressed two times daily for approximately 2 weeks until mice were able to regain normal blad- der function. Mice that underwent laminectomy without impact served as sham controls.

Treatment procedure:

The mice were randomly divided into IL-13, vehicle and sham groups. In IL-13 treatment group mice received 1 g of IL-13 via the tail vein immediately after wound closing, i.e within 30 minutes after SCI, followed by 1 g at 3 days post injury (dpi) and 0.5 g at 7 and 10 dpi. IL-13 administration did not cause any observable adverse effects.

Functional assessment:

Hindlimb motor function recovery was assessed using the Basso Mouse Scale (BMS) (Basso et al., 2006. J. Neurotrauma, 23, 635-659) by two raters blinded to the experimental groups as described in Pomeshchik et al. (2015 Brain Behav Immun. 44, 68-81 ). Motor function was assessed 24 h after injury, and then weekly for 28 days. Two mice in IL-13 treated group with obvious signs of urinary infection were excluded from the study.

Results

IL-13 treatment promotes functional recovery after SCI:

To evaluate the effect of IL-33 treatment on functional recovery we applied the BMS (Basso et al., 2006. J. Neurotrauma, 23, 635-659). Twenty-four hours after contusion SCI, most of the mice exhibited complete paralysis of hindlimbs (BMS score 0). During the next 4 weeks after SCI, we observed slow recovery of hindlimb function in both vehicle and IL-13 treated groups. At 14, 21 and 28 dpi the mice treated with IL-13 received higher scores than mice treated with vehicle (Figure 5). Example 3. IL-13 protects against white matter lesions - model of cerebrovascular dementia

Materials and Methods Animals:

All experimental procedures were approved by the Animal Experiment Committee in State Provincial Office of Southern Finland and conducted according to the na- tional regulation of the usage and welfare of laboratory animals. Adult 3 month old male C57BL/6J mice were used in this study. Animals were housed by 3 to 5 mice in a cage under 12-hour light/dark cycle with water and standard food provided ad libitum.

Surgery procedure and white matter injury:

Mice were randomized, anesthetized with 5% isoflurane in 30% 02 70% N2O and maintained in surgical depth of anesthesia during operation with 1 % to 1 .5% isoflurane delivered through a nose mask. The injury was induced as previously de- scribed (Rosenzweig S and Carmichael ST. 2013, Stroke 44(9):2579-86). During surgery mice were placed on thermostatically controlled heating blanket to maintain body temperature on constant level 37 ± 1 °. Mice were positioned in stereotaxic instruments (David Kopf Instruments, Tujunga, CA), and 375nl_ of L-N5-(1 - iminoethyl)ornitine (L-NIO) 27mg/ml in sterile PBS was injected intracranially in the posterior limb of internal capsule (PLIC) using a 5-μΙ Hamilton syringe with 33- gauge needle and an injecting minipump (Nanomite Injector Syringe Pump; Harvard Apparatus, Holliston, MA, USA). Two injections (each of 375 nL solution) were made at the rate of 200 nL per min in the following coordinates: A/P -1 .0; M/L -2.5; DA/ -3.2; A/P -1 .4; M/L -2.8; DA/ -3.5; at an angle of 10° with a dorso- posterior to ventro-anterior injection path (for all two injections). The needle was left in situ for 7 min after injection before being slowly raised, and the wound was sutured. Analgesia was provided with buprenorfine (Temgesic®, Schering-Plough, Belgium) 0.1 mg/kg injected s.c. 30 min before surgery. In the sham group, the mice were given two stereotaxic injections of 375nL of sterile PBS using the coor- dinates as above.

Treatment procedure:

One g of mouse recombinant IL-13 in 100 μΙ of PBS was administered via the tail vein immediately after wound closing, i.e within the 30 min after the first intracere- bral injection. Control mice and shams were injected with 100 μΙ of PBS using the same approach as the group treated with IL-13. IL-13 administration did not cause any observable adverse effects.

Motor performance (Rotarod):

Testing of motor impairment was performed with the Rota-Rod® apparatus (Ugo Basile, Comerio, Italy). The mouse was gently placed on the round rod facing away from the investigator and allowed to adapt to the slow rotating rod (5 rpm) for 30 s. Then, for the next 5 min the speed of rotation was increased stepwise up to 30 rpm. The latency to fall off (or spin three full rounds around the rod) after the 30s adaptation period was recorded until a 5-min cut-off time. The apparatus was cleaned with 70% ethanol before each mouse. The mice were tested before sur- gery (day -1 , baseline) and at day 3 after surgery. At both time-points the mice were tested in 3 consecutive trials with a 30 min period of rest between the trials. The results were the mean of three consecutive tests, expressed in % of baseline.

Magnetic resonance imaging:

Seven days after surgery the mice were anesthetized with isoflurane, positioned in a custom-made animal holder with warm water heating system and imaged using a 9.4 Tesla Varian scanner (Varian Inc, Palo Alto, CA) interfaced to a Varian Di- rectDrive console. A volume coil (diameter 35mm) was used as transmitter and receiver. Lesion volumes were determined from T2-prepared fast spin echo (FSE) images (echo time/repetition time of 40 ms/3000 ms, matrix size 128 ^* 256, field of view 19.2 ^* 19.2 mm2, slice thickness 0.8 mm and number of slices 12). Images were then analyzed using Aedes software (Kuopio, Finland) under MatLab program (Math-works, Natick, USA). Data was post-processed using in-house-built Matlab software (Aedes, http://aedes.uku.fi).

Statistical analysis:

All data are given as mean ± SEM. Unpaired t-test was employed for comparing means of two treatment groups. For multiply comparisons one-way ANOVA followed by Tukey's post hoc test was used. All statistical analysis were performed by GraphPad Prism version 5.03 for Windows (GraphPad Software, La Jolla, CA, http://www.graphpad.com).

Results IL-13 treatment results in a modest long-term reduction of lesion volume after white matter injury:

Intracerebral injection of the vasoconstrictor L-NIO is known to induce focal ischemia resulting in cell death and white matter destruction at the infarct core, and a peri-infarct zone of partial myelin, axon and oligodendrocyte loss (1 ). Seven days after L-NIO injection, MRI in the mouse showed a hyperintensity in the posterior limb of internal capsule (Figure 6A). IL-13 administration slightly reduced the lesion size (Figure 6B) at this time-point. IL-13 treatment improves motor performance after white matter injury:

The mice in sham group improved rotarod performance at 3 days by approximately 30% compared to baseline (Figures 7A and 7B). Intracerebral injection of the vasoconstrictor L-N IO resulted in significantly reduced improvement of motor performance compared to sham group, whereas the IL-13 treatment group was not statistically different from the sham mouse group (Figures 7A and 7B).

Example 4. iL-1 3 inhibits LPS induced macrophage pro-inflammatory activation and promotes resolution in y^o oiysaccharide (LPS) stimu!ated .macrophage _, n _, vitro inflammation model .

Materials and Methods RAW264.7 macrophages were exposed to LPS 25ng/ml (Sigma, 2330) for 12, 24, 36 and 48 hours in presence or absence of IL-13 20ng/ml (mouse recombinant, R&D systems). Cells were collected directly in growing media, washed once with PBS, and lysed in 1 Laemm!i buffer. The equal loading of the samples was determined by Coomassie staining, and comparable amounts of the protein were run on sodium dodecyl sulfate polyacryiamide gel electrophoresis (SDS-PAGE) gels and transferred to polyvinyl idene fluoride (PVDF) using Mini Trans-blot Electropho- retic Transfer Cell equipment (Bio-Rad). Membranes were then blocked and incubated with primary antibodies: anti-iNOS (Miiipore, ANB26, 1 :3000), anti-Argl (Santa Cruz, sc18351 , 1 :2000) overnight at 4°C. The membranes were washed with PBST and incubated for 2 h with horse radish peroxidase-conjugated antibodies (anti-goat IgG, dilution 1 :2000, anti-rabbit IgG, dilution 1 :2000; Amersham Biosciences or anti-goat IgG, dilution 1 :2000; Dako) and developed using enhanced chemiiuminescence (ECL-kit; GE Healthcare). Membranes were visualized on Storm 860 Fluoroimager (GE Healthcare).

Results

SDS-PAGE gels revealed that IL-1 3 inhibits LPS induced macrophage proinflammatory activation and promotes resolution in iipopolysaccharide (LPS) stimulated macrophage in vitro inflammation model (Figure 8, iNOS decreased and Arg1 increased). The inducible isoform of nitric oxide synthase, iNOS, is known to be involved in immune response, to bind calmodulin at physiologically relevant concentrations, and to produce nitric oxide as an immune defense mechanism, as nitric oxide is a free radical with an unpaired electron. Arg1 is an arginase catalyzing the hydroiy- sis of arginine to ornithine and urea.