Serum markers for type II diabetes mellitus

This invention was made with Government support under Contract DE-AC0576RLO1830 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.

1. Field of the Invention

The present invention generally relates to methods and systems for the screening and detection of disease and more particularly to methods and systems for the screening and detection of persons at risk for developing type II diabetes mellitus.

2. Background of the Invention

Type II diabetes mellitus is a life changing disease that affects millions of persons. While the disease may be clinically diagnosed and confirmed fairly easily in some cases, earlier detection may lead to the possibility of intervention(s) that would alter or lessen the onset of clinical symptoms or allow other forms of preventative care to be undertaken.

Currently, one of the best approaches for predicting who may be at risk for developing type II diabetes mellitus before onset of clinical symptoms is by the oral glucose tolerance test (OGTT). The OGTT, is inconvenient, requires fasting and is not highly reproducible. The fasting blood glucose (FBG) is less burdensome, but much less sensitive, particularly in older Americans who have the highest prevalence of diabetes and pre-diabetes. The quantitation of Hemoglobin A1c (a glycated form of hemoglobin) from blood has been widely used as a test for assessing the adequacy of glycemic control and risk of complications in diabetic patients, but this test is not sufficiently sensitive to detect the range of glucose values typically seen in pre-diabetes or new onset type II diabetes. Furthermore, there are many variants of hemoglobin present in blood. This is particularly applicable in minority populations disproportionately affected by diabetes, and this adds additional uncertainty to the use of this test. A simplified, less burdensome approach to the diagnosis of diabetes and pre-diabetes would facilitate increased recognition and improved care of these individuals. While progress has been made to improve the accuracy and reproducibility of the measurement of surrogate biomarkers predictive of those at high risk for developing type II diabetes, a set of candidate biomarkers would benefit the clinical community, particularly if such surrogate biomarkers result in higher sensitivity and specificity.

Accordingly, what is needed is a method and system of screening for persons with increased risk of developing type II diabetes mellitus that utilizes candidate biomarkers allowing for broad based, reliable screening of large population bases. In addition, effective strategies for characterizing, archiving, and contrasting data from multiple sample types under varying conditions (e.g. control versus disease) are also needed.

Additional advantages and novel features of the present invention will be set forth as follows and will be readily apparent from the descriptions and demonstrations set forth herein. Accordingly, the following descriptions of the present invention should be seen as illustrative of the invention and not as limiting in any way.

The present application describes a method for identifying persons with increased risk of developing type II diabetes mellitus utilizing selected biomarkers described hereafter either alone or in combination. The present invention allows for broad based, reliable screening of large population bases and provides other advantages including the formulation of effective strategies for characterizing, archiving, and contrasting data from multiple sample types under varying conditions. In one embodiment of the present invention, the markers are selected from the following:

(1) 163 kDa protein; peptide sequences:

LVHVEEPHTETVRK, MVSGFIPLKPTVK, DLKPAIVK,

DMYSFLEDMGLK, NEDSLVFVQTDK, SASNMAIVDVK,

TEHPFTVEEFVLPK, TTVMVK, FQVDNNNR, ATVLNYLPK,

(2) 45 kDa protein; peptide sequences:

(3) afamin; peptide sequences:

(4) alpha-2-macroglobulin; peptide sequences:

SASNMAIVDVK, RKEYEMK, ATVLNYLPK, FQVDNNNR,

DTVIKPLLVEPEGLEK, TEHPFTVEEFVLPK, NEDSLVFVQTDK,

DMYSFLEDMGLK, DLKPAIVK, MVSGFIPLKPTVK,

(5) apolipoprotein A-I; peptide sequences:

AHVDALR, SGRDYVSQFEGSALGK, PYLDDFQKK,

(6) apolipoprotein A-IV; peptide sequences:

(7) apolipoprotein B-100; peptide sequences:

(8) complement C4B1; peptide sequences:

GQIVFMNREPK, GPEVQLVAHSPWLK, SHALQLNNR,

(9) ceruloplasmin; peptide sequences:

(10) clusterin isoform 1; peptide sequences:

(11) clusterin; peptide sequences:

(12) complement C3; peptide sequences:

FYYIYNEK, LMNIFLK, IPIEDGSGEVVLSR, IWDVVEK,

TIYTPGSTVLYR, KGYTQQLAFR, RIPIEDGSGEVVLSR,

VQLSNDFDEYIMAIEQTIK, RQGALELIKK, AAVYHHFISDGVRK,

(13) complement C4; peptide sequences:

GPEVQLVAHSPWLK, SHALQLNNR, DFALLSLQVPLKDAK,

(14) complement C4A; peptide sequences:

GPEVQLVAHSPWLK, SHALQLNNR, DFALLSLQVPLKDAK,

(15) complement C4B; peptide sequences:

YIYGKPVQGVAYVR, GQIVFMNREPK, SHALQLNNR,

(16) FGA protein; peptide sequences:

DSHSLTTNIMEILR, GLIDEVNQDFTNR,

(17) gelsolin isoform b; peptide sequences:

(18) gelsolin; peptide sequences:

(19) hemopexin; peptide sequences:

LWWLDLK, RLWWLDLK,

(20) histidine-rich glycoprotein; peptide

sequences:

(21) Hypothetical protein DKFZp779N0926; peptide

sequences:

(22) Inter-alpha-trypsin inhibitor heavy chain H2

precursor; peptide sequences:

(23) pregnancy zone protein; peptide sequences:

(24) Similar to fibrinogen, A alpha polypeptide;

peptide sequences:

(25) Splice Isoform 1 of Inter-alpha-trypsin

inhibitor heavy chain H4; peptide sequences:

(26) Splice Isoform 2 of Inter-alpha-trypsin

inhibitor heavy chain H4; peptide sequences:

(27) Splice Isoform Alpha of Fibrinogen alpha/

alpha-E chain; peptide sequences:

MELERPGGNEITR, LKNSLFEYQK, DSHSLTTNIMEILR,

(28) Splice Isoform Alpha-E of Fibrinogen alpha/

alpha-E chain; peptide sequences:

LKNSLFEYQK, DSHSLTTNIMEILR, MELERPGGNEITR,

(29) Splice Isoform Gamma-A of Fibrinogen gamma

chain; peptide sequences:

(30) Splice Isoform Gamma-B of Fibrinogen gamma

chain; peptide sequences:

(31) Vitamin D-binding protein; peptide sequences:

The presence of the markers described herein may be determined and utilized in a variety of ways employing various methodologies and utilizing a variety of sample types. Thus while one embodiment of the invention related to the application of the markers of the present invention in serum or plasma is described, this description is intended to be illustrative only and not exclusive in any way. With appropriate modification such a method may also be utilized in other sample types. In this and comparing the quantity of the at least one serum constituent to a standardized range of levels for this constituent to determine whether the level of the serum constituent when compared to the normal range is indicative of a predisposition for type II diabetes mellitus. A system for performing the method of the present invention is made up of the requisite pieces and parts that would allow such a method to be performed.

In one embodiment of the present invention, the method for determining whether a person has an increased risk of developing type II diabetes mellitus involves the testing of human plasma or serum samples for the presence of the aforementioned biomarkers. Thus after plasma or serum is collected and appropriately processed, testing for the presence of these biomarkers is performed by capillary liquid chromatography-Fourier transform ion cyclotron resonance mass spectrometry of protein digests of these human plasma and serum samples. While these methods have been described and were utilized in testing, it is to be distinctly understood that the invention is not limited to any particular form of testing utilized, but is intended to include all methods that are capable of detecting the materials that are set forth in the claims.

In one particular embodiment of the invention, the method employed the testing of samples for the presence of the following proteins selected from the group of 31 set forth previously. This select group included the following:

(1) 163 kDa protein; peptide sequences:

LVHVEEPHTETVRK, MVSGFIPLKPTVK, DLKPAIVK,

DMYSFLEDMGLK, NEDSLVFVQTDK, SASNMAIVDVK,

TEHPFTVEEFVLPK, TTVMVK, FQVDNNNR, ATVLNYLPK,

(2) 45 kDa protein; peptide sequences:

(3) alpha-2-macroglobulin; peptide sequences:

SASNMAIVDVK, RKEYEMK, ATVLNYLPK, FQVDNNNR,

DTVIKPLLVEPEGLEK, TEHPFTVEEFVLPK, NEDSLVFVQTDK,

DMYSFLEDMGLK, DLKPAIVK, MVSGFIPLKPTVK,

(4) apolipoprotein B-100; peptide sequences:

(5) complement C4B1; peptide sequences:

GQIVFMNREPK, GPEVQLVAHSPWLK, SHALQLNNR,

(6) ceruloplasmin; peptide sequences:

(7) complement C3; peptide sequences:

FYYIYNEK, LMNIFLK, IPIEDGSGEVVLSR, IWDVVEK,

TIYTPGSTVLYR, KGYTQQLAFR, RIPIEDGSGEVVLSR,

VQLSNDFDEYIMAIEQTIK, RQGALELIKK, AAVYHHFISDGVRK,

(8) complement C4; peptide sequences:

GPEVQLVAHSPWLK, SHALQLNNR, DFALLSLQVPLKDAK,

(9) complement C4B; peptide sequences:

YIYGKPVQGVAYVR, GQIVFMNREPK, SHALQLNNR,

The results of this testing in non-diabetic, diabetic and control samples showed the presence of each of these proteins at significantly elevated levels in persons diagnosed with type II diabetes, while the normal and control samples did not have these elevated levels. Thus a method wherein human serum or plasma is tested for at least one protein from this list serves as an effective predictive or diagnostic screen or test for type II diabetes. In addition, the above listed proteins can be further explored in targeted proteomic studies utilizing isotopically-labeled peptide internal standards for absolute quantitation, which will enable the determination of laboratory-defined sensitivity and specificity with blinded samples. Further embodiments of the invention may also be made by combining various of these proteins, either alone or in combination with other biomarkers.

Various methods for performing the quantitative and qualitative analysis of these proteins may be utilized. In one preferred embodiment of the invention, LC-MS/MS analyses were performed, however it is to be distinctly understood that the invention is not limited thereto. Any reliable manner of performing quantitative or qualitative analysis of a sample for the presence and quantity of any of the preselected biomarkers previously set forth and discussed may be utilized.

The purpose of the foregoing is to enable the United States Patent and Trademark Office and the public generally, especially the scientists, engineers, and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection, the nature and essence of the technical disclosure of the application. The abstract is neither intended to define the invention of the application, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.