CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit to U.S. Provisional Patent Application No.

62/436,137, filed on December 19, 2016, which is hereby incorporated by reference in its entirety.

STATEMENT OF GOVERNMENT SUPPORT

[0002] This invention was made with government support under TR001108 and

RR020128 awarded by the National Institutes of Health. The government has certain rights in the invention.

STATEMENT IN SUPPORT FOR FILING A SEQUENCE LISTING

[0003] A computer readable form of the Sequence Listing containing the file named "IURTC_2017-062-02_ST25.txt", which is 8,388 bytes in size (as measured in MICROSOFT WINDOWS® EXPLORER), is provided herein and is herein incorporated by reference. This Sequence Listing consists of SEQ ID NOs:l-9.

BACKGROUND OF DISCLOSURE

[0004] The present disclosure relates to unmethylated and methylated DNA as biomarkers of an active inflammatory/autoimmune process. More particularly, the present disclosure relates to unmethylated and methylated preproinsulin (INS) DNA as biomarkers of sepsis.

[0005] During obesity, insulin resistance in the muscle, liver, and adipose tissue increases the demand for insulin secretion from the β cell to maintain glucose homeostasis. The inability of the β cell to fully compensate is a major factor in the progression from normoglycemia to dysglycemia and frank type 2 diabetes (T2D) in adults and youth. It has been known for over 60 years that β cell mass is reduced in individuals with T2D compared to obese and lean non-diabetic controls, suggesting that reductions in β cell mass might account for the loss of β cell function. The etiology underlying reduced β cell mass in T2D remains unclear, and it is possible that such reductions represent inherently lower β cell mass in these individuals. However, a predominant working hypothesis in the field is that dynamic loss of β cells with disease progression is the underlying cause. Studies from cadaveric donors suggest that β cell apoptosis accounts for β cell loss, whereas other findings in mice and humans suggest that dedifferentiation of β cells may also be a key feature.

[0006] Recently, the measurement of circulating unmethylated DNA encoding preproinsulin (INS) has been proposed as a biomarker of β cell death. Particularly, it was previously shown that INS DNA in β cells has a much higher frequency of unmethylated CpG sites compared to other cell types. Further, the relative abundance of unmethylated INS DNA in the circulation was shown to be elevated in both mice and humans with recent-onset T1D, and higher relative abundances correlated temporally to more active β cell destruction, β cells and many other cell types in the islet contain some fraction of both unmethylated and methylated INS DNA. In a differentially methylated DNA (DMD) assay used to monitor β cell death in vivo, cell-free unmethylated CpG sites in preproinsulin (INS) DNA in circulation reflected DNA liberated from dying β cells with methylated CpG sites in preproinsulin (INS) DNA in the circulation presumably representing DNA liberated from dying η η-β cells that had dedifferentiated. It is unknown whether differentially methylated DNA can be attributed to β cell death and/or dedifferentiation in different populations with obesity, pre-T2D and T2D. The loss of functional β cell mass is believed to underlie virtually all forms of diabetes, but in T2D the primary etiology remains unclear.

[0007] Sepsis is a potentially life-threatening complication of an infection. Sepsis occurs when chemicals released into the bloodstream to fight the infection trigger inflammatory responses throughout the body. This inflammation can trigger a cascade of changes that can damage multiple organ systems, causing them to fail. Diagnosis is based on sepsis-related organ failure assessment score (SOFA) to determine the extent of a patient's organ function or rate of failure. Scoring is based on six different scores for the respiratory, cardiovascular, hepatic, coagulation, renal and neurological systems. The quick SOFA score provides an initial way to identify patients at high risk for poor outcome with an infection. The qSOFA simplifies the SOFA score by only including its 3 clinical criteria and by including "any altered mentation". Early diagnosis is necessary for properly managing sepsis and to reduce mortality from severe sepsis.

[0008] Accordingly, there is a need for biomarkers and diagnostic methods for evaluating biomarkers that are specific for inflammation and autoimmunity. BRIEF DESCRIPTION

[0009] The present disclosure is generally related to evaluating circulating methylated and unmethylated DNA that are specific for inflammation.

[0010] Accordingly, in one aspect, the present disclosure is directed to use of a circulating unmethylated DNA, a circulating methylated DNA, and combinations thereof as a biomarker for systemic inflammation.

[0011] In another aspect, the present disclosure is directed to use of a circulating unmethylated DNA, a circulating methylated DNA, and combinations thereof as a biomarker for sepsis.

[0012] In another aspect, the present disclosure is directed to a method for detecting sepsis in a subject having or suspected of having sepsis. The method comprises: amplifying methylated preproinsulin DNA in a sample obtained from the subject; amplifying unmethylated preproinsulin DNA in the sample obtained from the subject; detecting whether a nucleotide from the preproinsulin transcriptional start site is methylated or unmethylated; comparing the concentration of methylated preproinsulin DNA and the concentration of unmethylated preproinsulin DNA from the subject to the concentration of methylated preproinsulin DNA and the concentration of unmethylated preproinsulin DNA from a subject not having or suspected of having sepsis; and diagnosing the subject as being suspected of having sepsis if the concentration of methylated preproinsulin DNA from the subject are elevated when compared to the concentration of methylated preproinsulin DNA of the control.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The disclosure will be better understood, and features, aspects and advantages other than those set forth above will become apparent when consideration is given to the following detailed description thereof, such detailed description makes reference to the following drawings, wherein:

[0014] FIGS. 1A and IB depict mouse DMD assay specificity and validation. FIG. 1A depicts two-dimensional plots using plasmid standards for unmethylated and methylated mouse Ins2 DNA and for a 1 :1 mixture of the two plasmids. Arrows identify the unmethylated, methylated, and unmethylated + methylated (double-positive) Ins2 DNA-containing droplets. FIG. IB depicts quantitation of plasmid dilution curves, presented as copies/μΐ. FIGS. 1C and ID depict quantitation of dilution curves of serum spiked with mouse DNA for (FIG. 1C) unmethylated Ins2 DNA and (FIG. ID) methylated Ins2 DNA. R2 = 0.9733 for unmethylated Ins2 DNA and R2 = 0.9917 for methylated Ins2 DNA.

[0015] FIG. 2A depicts body weight measurements of C57BL/6J mice fed a low fat diet (LFD) or high fat diet (HFD) and treated with STZ to induce β cell death. N=6-12 mice total for each of 4 groups, done on two separate occasions. Data are presented as mean + SEM; *P<0.05 compared to LFD. #P<0.05 compared to no-STZ.

[0016] FIG. 2B depicts fasting blood glucose measurements of C57BL/6J mice fed a low fat diet (LFD) or high fat diet (HFD) and treated with STZ to induce β cell death. N=6-12 mice total for each of 4 groups, done on two separate occasions. Data are presented as mean + SEM; *P<0.05 compared to LFD. #P<0.05 compared to no-STZ.

[0017] FIG. 2C depicts area under the curve of intraperitoneal glucose tolerance tests of C57BL/6J mice fed a low fat diet (LFD) or high fat diet (HFD) and treated with STZ to induce β cell death. N=6-12 mice total for each of 4 groups, done on two separate occasions. Data are presented as mean + SEM; *P<0.05 compared to LFD. #P<0.05 compared to no-STZ.

[0018] FIG. 2D depicts β cell mass of C57BL/6J mice fed a low fat diet (LFD) or high fat diet (HFD) and treated with STZ to induce β cell death. N=6-12 mice total for each of 4 groups, done on two separate occasions. Data are presented as mean + SEM; *P<0.05 compared to LFD. #P<0.05 compared to no-STZ.

[0019] FIG. 2E depicts circulating unmethylated Ins2 DNA levels of C57BL/6J mice fed a low fat diet (LFD) or high fat diet (HFD) and treated with STZ to induce β cell death. N=6-12 mice total for each of 4 groups, done on two separate occasions. Data are presented as mean + SEM; *P<0.05 compared to LFD. #P<0.05 compared to no-STZ.

[0020] FIG. 2F depicts circulating methylated Ins2 DNA levels of C57BL/6J mice fed a low fat diet (LFD) or high fat diet (HFD) and treated with STZ to induce β cell death. N=6- 12 mice total for each of 4 groups, done on two separate occasions. Data are presented as mean + SEM; *P<0.05 compared to LFD. #P<0.05 compared to no-STZ.

[0021] FIG. 3A depicts blood glucose levels of C57BLKS/J-db/db (db/db, N=16) and C57BLKS/J-db/+ (db/+, N=16) followed between 6-10 weeks of age. [0022] FIG. 3B depicts circulating unmethylated Ins2 DNA levels of C57BLKS/J- db/db (db/db, N=16) and C57BLKS/J-db/+ (db/+, N=16) followed between 6-10 weeks of age. Data are shown as mean + SEM, *P<0.05 compared to corresponding values in db/+ animals.

[0023] FIG. 3C depicts circulating methylated Ins2 DNA levels of C57BLKS/J- db/db (db/db, N=16) and C57BLKS/J-db/+ (db/+, N=16) followed between 6-10 weeks of age. Data are shown as mean + SEM, *P<0.05 compared to corresponding values in db/+ animals.

[0024] FIG. 4A depicts regression analyses correlating clinical characteristics and circulating unmethylated INS DNA in human cohorts vs. age in healthy control individuals.

[0025] FIG. 4B depicts regression analyses correlating clinical characteristics and circulating methylated INS DNA in human cohorts vs. age in healthy control individuals.

[0026] FIG. 4C depicts regression analyses correlating clinical characteristics and circulating unmethylated and methylated INS DNA vs. age in youth (<21) years old) and adult (>21 years old) healthy control individuals.

[0027] FIG. 4D depicts regression analyses correlating clinical characteristics and circulating unmethylated and methylated INS DNA vs. BMI Z-Score or BMI in youths and adults.

[0028] FIG. 4E depicts regression analyses correlating clinical characteristics and circulating unmethylated and methylated INS DNA vs. HbAlC in youths and adults.

[0029] FIG. 5A depicts circulating unmethylated INS DNA in adult lean controls with normal glucose tolerance (NGT) and cohorts with obesity and normal glucose tolerance (OB-NGT), impaired glucose tolerance (IGT) and type 2 diabetes (T2D). Data are presented as mean + SEM. *P<0.05 for the comparisons indicated.

[0030] FIG. 5B depicts circulating methylated INS DNA in adults with NGT,

OB-NGT, IGT, and T2D. Data are presented as mean + SEM. *P<0.05 for the comparisons indicated.

[0031] FIG. 5C depicts circulating unmethylated INS DNA in youth lean controls

(NGT) and obese youth with normal glucose tolerance (OB-NGT), IGT and clinician diagnosed T2D without autoantibodies (T2D-AAb-) and T2D with autoantibodies (T2D-AAb+). Data are presented as mean + SEM. *P<0.05 for the comparisons indicated.

[0032] FIG. 5D depicts circulating methylated INS DNA in youth with NGT, OB-

NGT, IGT, T2D-AAb-, T2D-AAb+. Data are presented as mean + SEM. *P<0.05 for the comparisons indicated.

[0033] FIG. 6 A depicts the determination of unmethylated INS DNA as a percentage of total INS DNA released into the medium from EndoC-βΗΙ and human islets treated with cytokine mix (IL-Ιβ and IFN-γ) for the indicated times. Data are presented as mean + SEM. *P<0.05 compared to Control.

[0034] FIG. 6B depicts unmethylated INS DNA as a percent of total INS DNA in the cellular fraction of EndoC-βΗΙ cells and human islets following treatment with cytokine mix (IL-Ιβ and IFN-γ). Data are presented as mean + SEM. *P<0.05 compared to Control.

[0035] FIG. 6C depicts circulating unmethylated INS DNA in healthy youth

(Control) and youth with inflammatory bowel disease (IBD) and Sepsis. Data are presented as mean + SEM. *P<0.05 compared to Control.

[0036] FIG. 6D depicts circulating methylated INS DNA in Control youth and youth with IBD and Sepsis. Data are presented as mean + SEM. *P<0.05 compared to Control.

[0037] While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described below in detail. It should be understood, however, that the description of specific embodiments is not intended to limit the disclosure to cover all modifications, equivalents and alternatives falling within the scope of the disclosure as defined by the appended claims.

DETAILED DESCRIPTION

[0038] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure belongs. Although any methods and materials similar to or equivalent to those described herein can be used in the practice or testing of the present disclosure, the preferred methods and materials are described below. [0039] As used herein, "a subject in need thereof" (also used interchangeably herein with "a patient in need thereof") refers to a subject susceptible to or at risk of a specified disease, disorder, or condition. The methods of screening circulating methylated and unmethylated DNA can be used with a subset of subjects who are susceptible to or at elevated risk of systemic inflammation. The methods of screening circulating methylated and unmethylated DNA can be used with a subset of subjects who are susceptible to or at elevated risk of sepsis.

[0040] Based on the foregoing, because some of the method embodiments of the present disclosure are directed to specific subsets or subclasses of identified subjects (that is, the subset or subclass of subjects "in need" of assistance in addressing one or more specific conditions noted herein), not all subjects will fall within the subset or subclass of subjects as described herein for certain diseases, disorders or conditions.

[0041] As used herein, "susceptible" and "at risk" refer to having little resistance to a certain disease, disorder or condition, including being genetically predisposed, having a family history of, and/or having symptoms of the disease, disorder or condition.

Methods for Diagnosing systemic inflammation using circulating unmethylated DNA and methylated DNA

[0042] In one aspect, the present disclosure is directed to use of a circulating unmethylated DNA, a circulating methylated DNA, and combinations thereof as a biomarker for systemic inflammation. The method includes amplifying methylated preproinsulin DNA in a sample obtained from the subject suspected of having sepsis; amplifying unmethylated preproinsulin DNA in the sample obtained from the subject suspected of having sepsis; detecting whether a nucleotide of the preproinsulin DNA is methylated or unmethylated; comparing the concentration of methylated preproinsulin DNA and unmethylated preproinsulin DNA in the sample with the concentration of methylated preproinsulin DNA and unmethylated preproinsulin DNA in a control subject; and determining that the subject has systemic inflammation when the concentration of methylated preproinsulin DNA in the sample is greater than the concentration of methylated preproinsulin DNA in the control subject.

[0043] Suitable methylated and unmethylated DNA includes methylated and unmethylated human preproinsulin (INS) DNA and methylated and unmethylated mouse preproinsulin (Ins2) DNA. In particular, a nucleotide located at position -69 from the transcriptional start site of the human INS DNA is analyzed. In another embodiment, a nucleotide located at position - 182 from the transcriptional start site of the mouse Ins2 DNA is analyzed.

[0044] A particularly suitable reference sequence for identifying position -69 of the human INS DNA can be found in the preproinsulin gene provided by GenBank Accession number V00565 (GI:33930; Ensembl number: ENS G00000254647; provided herein as SEQ ID NO:9).

[0045] A particularly suitable reference sequence for identifying position -182 of the mouse Ins2 DNA can be found in the mouse preproinsulin (Ins2) gene provided by GenelD: 16334.

[0046] Suitable amplification methods are known to those skilled in the art such as, for example, polymerase chain reaction and isothermal amplification methods. Suitable polymerase chain reaction methods for amplifying preproinsulin (human INS and mouse Ins2) DNA are known to those skilled in the art. A particularly suitable amplification method includes DROPLET DIGITAL™ PCR (ddPCR™). ddPCR™ technology employs the analysis of discrete individual PCR reactions (up to 20,000/sample) to identify the absence or presence of the target DNA, and subsequently utilizes Poisson statistics to extrapolate the number of copies of the target DNA in the sample.

[0047] In one aspect, the nucleotide located at position -69 from the human preproinsulin (INS) transcriptional start site is cytosine. In one aspect, the nucleotide located at position -182 from the mouse preproinsulin (Ins2) transcriptional start site is cytosine.

[0048] In one aspect, the method includes amplifying the methylated preproinsulin DNA in the sample using an oligonucleotide comprising SEQ ID NO:3. In another aspect, the method includes amplifying the unmethylated preproinsulin DNA in the sample using an oligonucleotide comprising SEQ ID NO:4. In another aspect, the methylated preproinsulin DNA in the sample the unmethylated preproinsulin DNA in the sample is amplified using a primer pair, wherein the primer pair includes an oligonucleotide comprising SEQ ID NO:3 and an oligonucleotide comprising SEQ ID NO:4. [0049] In another aspect, the method further includes amplifying the preproinsulin (INS) promoter. The preproinsulin promoter can be amplified using a first oligonucleotide comprising SEQ ID NO: l and a second oligonucleotide comprising SEQ ID NO:2.

[0050] In another aspect, the method further includes determining the concentration of methylated preproinsulin DNA. The methylated human preproinsulin DNA is methylated at a nucleotide located at position -69 from the human preproinsulin transcriptional start site. The nucleotide located at position -69 from the human preproinsulin transcriptional start site is cytosine. The methylated mouse preproinsulin DNA is methylated at a nucleotide located at position - 182 from the mouse preproinsulin transcriptional start site. The nucleotide located at position - 182 from the mouse preproinsulin transcriptional start site is cytosine. As described herein, statistics such as, for example, Poisson statistics, can be used to extrapolate the number of copies, and thus, the concentration of the methylated and unmethylated preproinsulin DNA in the sample.

[0051] In another aspect, the method further includes determining the concentration of unmethylated preproinsulin DNA. The unmethylated human preproinsulin DNA is methylated at a nucleotide located at position -69 from the human preproinsulin transcriptional start site. The nucleotide located at position -69 from the human preproinsulin transcriptional start site is cytosine. The unmethylated mouse preproinsulin DNA is methylated at a nucleotide located at position - 182 from the mouse preproinsulin transcriptional start site. The nucleotide located at position - 182 from the mouse preproinsulin transcriptional start site is cytosine.

[0052] In another aspect, the method includes subjecting (i.e., treating) the preproinsulin DNA in the sample to a bisulfite reaction. The preproinsulin DNA can suitably be treated alone after isolation and purification from the sample and the preproinsulin DNA can suitably be treated with all (the total) or part of the DNA in the sample. The preproinsulin DNA is subjected to a bisulfite reaction by treating the preproinsulin DNA, the part of the DNA, and/or the total DNA with bisulfite. The bisulfite treatment can be performed using standard methods such as, for example, EZ DNA METHYLATION™ kit (commercially available from Zymo Research, Irvine, CA) and EZ DNA METHYLATION-LIGHTNING Kit (commercially available from Zymo Research, Irvine, CA). Treatment of DNA with bisulfite results in the conversion of unmethylated cytosines to uracils. [0053] In another aspect, the copy number per microliter of methylated preproinsulin DNA and the copy number per microliter of unmethylated preproinsulin DNA are calculated.

[0054] Suitable samples can be serum, plasma, whole blood and urine.

Particularly suitable samples include serum, plasma and urine. Total DNA and preproinsulin DNA can be extracted from serum and plasma using standard methods such as, for example, ZR SERUM DNA Kit™ (commercially available from Zymo Research, Irvine, CA) and QIAamp DNA blood mini kit (commercially available from QIAGEN, Germantown, MD). Preproinsulin (INS) DNA can be extracted from urine using standard methods such as, for example, ZR URINE DNA Kit™ (commercially available from Zymo Research, Irvine, CA), for example.

[0055] The concentration of methylated DNA and unmethylated DNA can be determined by measuring fluorescence. The concentration of methylated preproinsulin DNA and unmethylated preproinsulin DNA can be determined by measuring fluorescence. Fluorescence can be measured at 518 nm, 548 nm, and 582.

[0056] Suitable control subjects include, for example, a healthy adult subject, a healthy pediatric subject, a subject having type 1 diabetes for at least 8 weeks, a subject having type 1 diabetes for at least one year, an adult with obesity, an adult having type 2 diabetes, an adult having auto-immune hepatitis, and combinations thereof.

Methods for Diagnosing Sepsis in a Subject

[0057] In another aspect, the present disclosure is directed to a method for diagnosing sepsis in a subject suspected of having sepsis. The method includes amplifying methylated preproinsulin DNA in a sample obtained from the subject suspected of having sepsis; amplifying unmethylated preproinsulin DNA in the sample obtained from the subject suspected of having sepsis; detecting whether a nucleotide is methylated or unmethylated; comparing the concentration of methylated preproinsulin DNA and unmethylated preproinsulin DNA in the sample with the concentration of methylated preproinsulin DNA and unmethylated preproinsulin DNA in a control subject; and determining that the subject has sepsis when the concentration of methylated preproinsulin DNA in the sample is greater than the concentration of methylated preproinsulin DNA in the control subject. [0058] In one aspect, the nucleotide located at position -69 from the human preproinsulin (INS) transcriptional start site is cytosine. In one aspect, the nucleotide located at position - 182 from the mouse preproinsulin (Ins2) transcriptional start site is cytosine.

[0059] A particularly suitable reference sequence for identifying position -69 from the human preproinsulin (INS) transcriptional start site can be found in the preproinsulin gene having the GenBank Accession number V00565 (GI:33930; Ensembl number:

ENSG00000254647; provided herein as SEQ ID NO:9).

[0060] A particularly suitable reference sequence for identifying position - 182 from the mouse preproinsulin (Ins2) transcriptional start site can be found in the mouse preproinsulin (Ins2) gene having the GenelD: 16334.

[0061] Suitable amplification methods are known to those skilled in the art such as, for example, polymerase chain reaction and isothermal amplification methods. Suitable polymerase chain reaction methods for amplifying preproinsulin (human INS and mouse Ins2) DNA are known to those skilled in the art. A particularly suitable amplification method is DROPLET DIGITAL™ PCR (ddPCR™). ddPCR™ technology employs the analysis of discrete individual PCR reactions (up to 20,000/sample) to identify the absence or presence of the target DNA, and subsequently utilizes Poisson statistics to extrapolate the number of copies of the target DNA in the sample.

[0062] In one aspect, the nucleotide located at position -69 from the human preproinsulin (INS) transcriptional start site is cytosine. In one aspect, the nucleotide located at position - 182 from the mouse preproinsulin (Ins2) transcriptional start site is cytosine.

[0063] In one aspect, the method includes amplifying the methylated preproinsulin DNA in the sample using an oligonucleotide comprising SEQ ID NO:3. In another aspect, the method includes amplifying the unmethylated preproinsulin DNA in the sample using an oligonucleotide comprising SEQ ID NO:4. In another aspect, the methylated preproinsulin DNA in the sample the unmethylated preproinsulin DNA in the sample is amplified using a primer pair, wherein the primer pair includes an oligonucleotide comprising SEQ ID NO:3 and an oligonucleotide comprising SEQ ID NO:4.

[0064] In another aspect, the method further includes amplifying the preproinsulin promoter. The preproinsulin promoter can be amplified using a first oligonucleotide comprising SEQ ID NO: l and a second oligonucleotide comprising SEQ ID NO:2.

[0065] In another aspect, the method further includes determining the concentration of methylated preproinsulin DNA. The methylated human preproinsulin DNA is methylated at a nucleotide located at position -69 from the human preproinsulin transcriptional start site. The nucleotide located at position -69 from the human preproinsulin transcriptional start site is cytosine. The methylated mouse preproinsulin DNA is methylated at a nucleotide located at position - 182 from the mouse preproinsulin transcriptional start site. The nucleotide located at position - 182 from the mouse preproinsulin transcriptional start site is cytosine. As described herein, statistics such as, for example, Poisson statistics, can be used to extrapolate the number of copies, and thus, the concentration of the methylated and unmethylated preproinsulin DNA in the sample.

[0066] In another aspect, the method further includes determining the concentration of unmethylated preproinsulin DNA. The unmethylated human preproinsulin (INS) DNA is methylated at a nucleotide located at position -69 from the preproinsulin (INS) transcriptional start site. The nucleotide located at position -69 from the human preproinsulin (INS) transcriptional start site is cytosine. The unmethylated mouse preproinsulin (Ins2) DNA is methylated at a nucleotide located at position - 182 from the preproinsulin (Ins2) transcriptional start site. The nucleotide located at position - 182 from the mouse preproinsulin (Ins2) transcriptional start site is cytosine.

[0067] In another aspect, the method includes subjecting (i.e., treating) the preproinsulin DNA in the sample to a bisulfite reaction. The preproinsulin DNA can suitably be treated alone after isolation and purification from the sample and the preproinsulin DNA can suitably be treated with all (the total) or part of the DNA in the sample. The preproinsulin DNA is subjected to a bisulfite reaction by treating the preproinsulin DNA and/or the total DNA with bisulfite. The bisulfite treatment can be performed using standard methods such as, for example, EZ DNA METHYLATION™ kit (commercially available from Zymo Research, Irvine, CA) and EZ DNA METHYLATION-LIGHTNING Kit (commercially available from Zymo Research, Irvine, CA). Treatment of DNA with bisulfite results in the conversion of unmethylated cytosines to uracils. [0068] In another aspect, the copy number per microliter of methylated preproinsulin DNA and the copy number per microliter of unmethylated preproinsulin DNA are determined.

[0069] Suitable samples can be serum, plasma, whole blood and urine.

Particularly suitable samples include serum, plasma and urine. Total DNA and preproinsulin DNA can be extracted from serum and plasma using standard methods such as, for example, ZR SERUM DNA Kit™ (commercially available from Zymo Research, Irvine, CA) and QIAamp DNA blood mini kit (commercially available from QIAGEN, Germantown, MD). Preproinsulin DNA can be extracted from urine using standard methods such as, for example, ZR URINE DNA Kit™ (commercially available from Zymo Research, Irvine, CA), for example.

[0070] The concentration of methylated DNA and unmethylated DNA can be determined by measuring fluorescence. The concentration of methylated preproinsulin DNA and unmethylated preproinsulin DNA can be determined by measuring fluorescence. Fluorescence can be measured at 518 nm, 548 nm, and 582.

[0071] Suitable control subjects include, for example, a healthy pediatric subject, a subject having type 1 diabetes for at least 8 weeks, a subject having type 1 diabetes for at least one year, a healthy adult subject, an adult with obesity, an adult having type 2 diabetes, an adult having auto-immune hepatitis, and combinations thereof.

[0072] Various functions and advantages of these and other embodiments of the present disclosure will be more fully understood from the examples described below. The following examples are intended to illustrate the benefits of the present disclosure, but do not exemplify the full scope of the disclosure.

EXAMPLES

Materials and Methods

Human subjects

[0073] Serum samples were obtained from male and female adult subjects 18-65 years of age. After an overnight fast, subjects underwent an oral glucose tolerance test (OGTT) with 75 g glucose. Subjects were divided into three categories based on OGTT 2hr-glucose concentrations: normal glucose tolerance (controls, <140 mg/dL), impaired glucose tolerance (IGT; 140-199 mg/dL), and T2D (>200 mg/dL). Exclusion criteria included: Metformin use 4 weeks previous, thiazolidinediones use 6 months previous, T1D, other diabetes, pregnancy, weight fluctuation 6 months previous, current or past tobacco use, acute or chronic illness, pulmonary disease, or use of antidepressants. Serum samples were collected from male and female 6-20 years of age enrolled at Riley Children's Hospital with no disease history (controls), active inflammatory bowel disease (IBD) or acute sepsis. Participants were provided written informed consent for screening and study participation. The study was approved by the Indiana University School of Medicine Institutional Review Board.

[0074] Frozen serum samples from 150 youth ages 10 to <20 years old (Table 2) who participated in NIH-funded K24 grant of "Childhood Insulin Resistance" were used in the present analysis. Participants were recruited through newspaper advertisements, flyers posted in the medical campus, city bus routes and the outpatient clinics in the Weight Management and Wellness Center and the Division of Pediatric Endocrinology. The study was approved by the institutional review board of the University of Pittsburgh and written informed parental consent and child assent were obtained from all participants before any research participation in accordance with the ethical guidelines of Children's Hospital of Pittsburgh. A 2-hr OGTT was performed in obese participants as described before. GAD 65 kDa autoantibody and insulinoma- associated protein 2 autoantibody (IA2) were measured using the NIDDK standardized assay protocol as described before. Participants with diabetes were on either lifestyle-only, or metformin or metformin plus insulin.

Human Islet and Cell Line

[0075] Human islets were obtained from the Integrated Islet Distribution Program (IIDP). βΗΙ cells and human islets were incubated with cytokines (50 U/ml IL-Ιβ and 1000 U/ml IFN-γ) for 0, 24, or 72 hours. Following incubation, DNA was extracted from both the cells and the supernatant.

Animals

[0076] Male C57BL/6J mice, C57BL/KsJ-db/db, and C57BL/KsJ-db/+ mice were obtained from the Jackson Laboratories and maintained under protocols approved by the Indiana University School of Medicine Institutional Animal Care and Use Committee or by the Lilly Research Labs Institutional Animal Care and Use Committee. C57BL/6J mice were acclimated for 1 week prior to being placed on either a low fat diet (10% kcal from fat, Research Diets; D12450B) or high fat diet (60% kcal from fat; Research Diets; D12492) starting at 8 weeks of age. C57BL/KsJ-db/db, and C57BL/KsJ-db/+ mice were feed a regular chow diet (Research Diets; 5008). Blood was harvested from the tail vein and processed as serum for the DMD assay. All mice were monitored for body weight and random blood glucose weekly. C57BL/6J mice underwent a glucose tolerance test using 2 g/kg lean mass after an overnight fast. A subset of C57BL/6J mice from each group was euthanized biweekly and pancreata were harvested for β cell mass measurements. After 10 weeks of diet treatment, a subset of C57BL6/J mice received streptozocin (STZ) at 55 mg/kg body weight daily for 5 days.

DNA extraction and bisulfite treatment

[0077] DNA was isolated from 20-50 μΐ of serum or cellular supernatant using

QIAamp DNA Blood Mini Kit (Qiagen) with 5 μg poly-A as a carrier. Cellular DNA was isolated using GenElute Mammalian Genomic DNA Miniprep Kit (Sigma-Aldrich). All samples then underwent bisulfite conversion using the EZ DNA Methylation kit or the EZ DNA Methylation- Lightning kit (Zymo Research), and conversion was verified using a pre- and postconversion sample in the ddPCR.

DMD Assay

[0078] Primers and dual-fluorescent probes for interrogating methylation at CpG position

-69 at the human INS gene and at position -182 at the mouse Ins2 gene were described in Fisher et al. and (Diabetes 2015; 64(l l):3867-3872) and Fisher et al. (Endocrinology 2013; 154(9):3476-3481). The DMD assay using droplet digital PCR (ddPCR) using primers and probes for mouse Ins2 and human INS were described in Fisher et al. and (Diabetes 2015; 64(l l):3867-3872).

PCR Analysis

[0079] Each sample was analyzed by ddPCR utilizing a custom designed dual fluorescent probe-based multiplex assay. For amplification of the human INS promoter, the following primers were used: 5 ' -GGAAATTGTAGTTTTAGTTTTTAGTTATTTGT-3 ' (forward) (SEQ ID NO:l); 5 '-AAAACCCATCTCCCCTACCTATCA-3 ' (reverse) (SEQ ID NO:2) in combination with the following probes that detected methylation or unmethylation at position -69 relative to the transcriptional start site: 5 '-ACCCCTACCGCCTAAC-3 ' (VIC) - methylated (SEQ ID NO:3); 5'-ACCCCTACCACCTAAC-3 ' (FAM) - unmethylated (SEQ ID NO:4). Primers and probes for mouse Ins2 DNA are as follows: primers used included 5'- AATTGGTTTATTAGGTTATTAGGGTTTTTTGTTAAGATTTTA-3' (forward) (SEQ ID NO:5); 5 '- ACTAAAACTACAATTTCCAAACACTTCCCTAA-3 ' (reverse) (SEQ ID NO:6); probes used included: 5'-CTCATTAAACGTCAACACC-3' (VIC) (SEQ ID NO:7); 5'- CTC ATT AA AC ATC A AC ACC- 3 ' (FAM) (SEQ ID NO:8).

[0080] The PCR was performed using ddPCR Supermix for Probes (No dUTP)

(Bio-Rad Laboratories, Inc., Hercules, CA) with the following cycling conditions: 95 °C for 10 minutes, 94 °C for 30 seconds, 57.5 °C for 60 seconds for 40 amplification cycles. Droplets were analyzed by the QX200 Droplet Reader and QuantaSoft Software (Bio-Rad Laboratories, Inc., Hercules, CA), from which an absolute concentration (copies/μΐ) of methylated and unmethylated INS DNA was obtained in each subject's sample. This final concentration was extrapolated to copies of unmethylated or methylated INS DNA/μΙ serum, then log-transformed for parametric statistical analysis.

Morpho metric assessment of β cell mass

[0081] Pancreata from at least three different mice per group were fixed in 4% paraformaldehyde, paraffin embedded, and sectioned onto glass slides. The β cell mass was calculated as described in Maier et al. (J. Clin. Invest. 2010; 12(6):2156-2170).

Statistical Analysis

[0082] All data are presented as mean +SEM. For comparisons of methylated and unmethylated mouse Ins2 DNA levels, a two-tailed unpaired Student's t test was used. For analysis of methylated and unmethylated INS DNA levels, a Kruskal-Wallis (non-parametric) test was employed followed by a Dunnett's post-test (to compare values to healthy controls). Statistical significance was determined at P<0.05.

EXAMPLE 1

[0083] In this Example, β cell death in mouse models of obesity and T2D was determined.

[0084] To assess β cell death in mouse models of obesity and T2D, the established real-time PCR-based DMD assay (described in Fisher et al., Endocrinology. 2013 Sep; 154(9):3476-81) was modified for compatibility with the more sensitive and specific ddPCR technique that allows for absolute quantitation of DNA copy numbers. The primers described in that study interrogated differential methylation at cytosine at position -182 bp (relative to the transcriptional start site) of the mouse Ins2 gene. The specificity of the primers in ddPCR was validated using plasmids containing cloned methylated or unmethylated Ins2 gene. As shown in the 2-dimensional ddPCR plots in FIG. 1A, the primers quantitatively distinguished mixtures of these plasmids. FIGS. IB-ID show that the primers linearly and quantitatively detected mouse islet DNA spiked into mouse serum. This DMD assay was then applied to a mouse model of obesity and impaired glucose tolerance (IGT) followed longitudinally.

[0085] C57BL/6J mice were fed a high fat diet (HFD; 60% kcal from fat, 20% from protein, 20% from carbohydrate, Research Diets D 12492) starting at 8 weeks of age and compared to control mice fed a low fat diet (LFD; 10% kcal from fat). HFD-fed mice exhibited statistically increased body weights and fasting blood glucose values compared to control LFD- fed animals beginning at 6 weeks after starting the diet (FIGS. 2A and 2B). Notably, HFD-fed mice showed IGT by glucose tolerance test (GTT) as early as 2 weeks after starting the diet (FIG. 2C). β cell mass quantified histologically increased significantly in HFD-fed animals compared to controls by 6 weeks post diet initiation (FIG. 2D). Compared to LFD-fed control animals, HFD-fed mice exhibited episodic increases in unmethylated Ins2 DNA levels at 2 and 6 weeks post diet initiation (FIG. 2E), coincident with the time points where glucose levels, fasting and by GTT were elevated (FIGS. 2B and 2C)). By contrast, methylated Ins2 DNA levels were not statistically different in HFD-fed animals compared to controls across the feeding period. At 10 weeks after starting diet, mice were administered multiple low doses of STZ to induce overt β cell death. As shown in FIGS. 2E and 2F, both unmethylated and methylated Ins2 DNA levels increased significantly 1 week following STZ injections then declined to baseline levels.

EXAMPLE 2

[0086] In this Example, the DMD assay was tested in a mouse model of spontaneous T2D.

[0087] The db/db mouse on the C57BLK/sJ background is an inbred strain that harbors a mutation in the leptin receptor gene and exhibits obesity, insulin resistance, β cell dysfunction, and diabetes as early as 6 weeks of age on a normal chow diet. Sera was serially collected from C57BLKS/J -db/db (henceforth referred to as "db/db") and control C57BLKS/J- db/+ (henceforth referred to as "db/+") mice weekly from 6 to 10 weeks of age and subjected them to the DMD assay. As shown in FIG. 3 A, db/db mice remained significantly hyperglycemic compared to db/+ controls throughout this timeframe. No statistically significant differences were seen in unmethylated Ins2 DNA (FIG. 3B). Methylated Ins2 DNA exhibited a significant increase in db/db compared to db/+ controls at 7 weeks of age, but returned to control levels thereafter (FIG. 3C). Collectively, these studies indicated that β cell death (as assessed by unmethylated Ins2 DNA levels) occurred episodically during the development of obesity and dysglycemia in mice and acutely upon β cell killing by STZ, but persistent β cell death was not detectable by the DMD assay in an animal model of established T2D (db/db).

EXAMPLE 3

[0088] In this Example, the DMD assay was tested in samples from human cohorts.

[0089] To apply the DMD assay to samples from human cohorts, the previously- validated DMD assay that interrogates differential methylation of cytosine at position -69 bp (relative to the transcriptional start site) in the human INS gene was used. Sera frozen at -80 °C from cross-sectional cohorts of healthy individuals and subjects with obesity, IGT and T2D, ages 10-66 years old were tested (see clinical characteristics of adults and youth in Tables 1 and 2, respectively). As shown in FIG. 4A, whereas unmethylated INS from healthy control subjects did not exhibit significant association with age, methylated INS exhibited a statistically significant increase with age (P<0.0001)(FIG. 4B). Consequently, youth (<21 years old) and adult (>21 years old) cohorts were separately analyzed. Within each cohort of healthy controls, there was no significant correlations of age with unmethylated or methylated INS (FIG. 4C). When considering each cohort including all participants without and with disease (healthy controls, obese, IGT, T2D), there were no significant correlations between unmethylated or methylated INS and BMI/BMI Z-score (FIG. 4D) or HbAlc % (FIG. 4E).

EXAMPLE 4

[0090] In this Example, unmethylated and methylated INS DNA in adults and youths with obesity, IGT, and T2D was determined.

[0091] The adult cohorts were stratified into 4 groups: lean controls with normal glucose tolerance (NGT); overweight/obese with normal glucose tolerance (OB-NGT); impaired glucose tolerance (IGT); and type 2 diabetes mellitus (T2D). The clinical characteristics of these groups are shown in Table 1.

Table 1. Demographic and Laboratory Evaluation of Adult Cohorts.

[0092] As shown in FIGS. 5A and 5B, in this cross-sectional comparison none of the adult groups showed statistically significant differences in unmethylated (FIG. 5 A) or methylated (FIG. 5B) INS DNA compared to healthy controls. The youth cohorts were stratified into the same groups as the adults, but the T2D group was separated into autoantibody-negative (AAb-) and autoantibody-positive (AAb+) phenotypic T2D groups, given the high prevalence of T1D in this age population. The clinical characteristics of these groups are shown in Table 2.

Table 2. Demographic and Laboratory Data of Youth Cohorts

NGT OB-NGT IGT AAb- AAb+ P value

T2D T2D

Total (% male) 32 (56) 31 (35) 31 (35) 34 (47) 22 (45)

Age, years 13 + 0.2 14 + 0.3 15 + 0.4 15 + 0.3 14 + 0.5 <0.001

BMI, Z-Score -0.14 + 0.15 2.21 + 0.10 2.33 + 0.06 2.39 + 0.05 1.90 + 0.12 <0.001 (ZS)

HbAlc (%) 5.3 + 0.1 5.4 + 0.1 5.4 + 0.1 6.6 + 0.1 6.3 + 0.2 <0.001

Fasting glucose, 95.3 + 3.5 90.8 + 3.5 92.5 + 3.5 115.1 + 3.4 129.1 + 5.0 <0.001 mg/dL

2hr OGTT N/A 111.4 + 10.5 158.8 + 8.4 197.5 + 8.1 299.1 + 12.1 <0.001 glucose, mg/dL Treatment

modality n (%)

Lifestyle 7 (21) 2 (13)

Insulin 4 (12) 3 (19)

Metformin 16 (47) 2 (13)

Insulin & 7 (21) 9 (56) Metformin

[0093] As shown in FIG. 5C, there were no statistical differences in unmethylated

INS DNA among these cross-sectional cohorts of youths. By contrast, however, FIG. 5D shows that methylated 7N5 DNA was significantly elevated in obese youth with NGT (P=0.03), IGT (P=0.04), and T2D-AAb+ (P=0.002) compared to healthy non-obese controls.

EXAMPLE 5

[0094] In this Example, differentially methylated INS DNA was determined in inflammation and autoimmunity.

[0095] The elevation in cell- free methylated INS in T2D-AAb+ individuals is reminiscent of the elevations reported in youth with new-onset T1D (Fisher et al. Diabetes. 2015 Nov; 64(l l):3867-72). To determine if inflammation increased the frequency of methylation at INS position -69 bp, time course incubations of the human β cell line EndoC-βΗΙ and primary human islets was performed with proinflammatory cytokines IL-Ιβ and IFN-γ, differential methylation was then interrogated by the DMD assay in the cell-free supernatant (released DNA from dying cells) and in cells directly. As shown in FIG. 6A, unmethylated INS (as a percentage relative to total INS) released into the medium was unchanged during the incubation time course. In agreement with this finding, the percentage of unmethylated INS was also unchanged in cells themselves (FIG. 6B), indicating that methylation frequency at position -69 bp at the INS gene was not impacted by inflammation in β cells.

[0096] To further determine the relationship between inflammation and methylated INS DNA levels, the DMD assay was applied to serum from youth with an active organ-specific inflammatory disorder (inflammatory bowel disease, IBD) and with generalized inflammation (sepsis requiring intensive care unit-level care and with some requiring insulin therapy) (see Table 3).

Table 3. Demographic and Laboratory Evaluation of IBD and Sepsis cohorts.

[0097] As shown in FIGS. 6D and 6E, compared to controls, subjects with sepsis exhibited elevations in methylated (P<0.001) INS DNA levels but not unmethylated INS DNA, whereas subjects with IBD exhibited no statistically significant elevations in either DNA species.

[0098] These Examples applied the DMD assay to quantify circulating levels of unmethylated and methylated INS across a spectrum of states from obesity to T2D in mouse models and in cross-sectional cohorts of youth and adults. These Examples provide several new findings, notably (a) circulating unmethylated INS, a biomarker of β cell death, increased episodically and transiently during the development of obesity and glucose intolerance in mice, but was not persistently elevated in established T2D, (b) in cross-sectional cohorts of adults and youth with obesity and T2D, sustained β cell death was not evident, and (c) in youth, elevations in circulating methylated INS was a biomarker of aggressive inflammatory states.