Urine and serum biomarkers associated with diabetic nephropathy

A method for determining diabetic nephropathy stage in a subject, comprising:

• obtaining a urine sample, and optionally, a serum sample, from a subject suspected of having diabetic nephropathy;
• determining the level of each of a plurality of biomarkers in the sample(s), and optionally, one or more clinical factors, the one or more clinical factors being selected from the group consisting of age, gender, HbA1c, albumin/creatinine ratio, and glomerular filtration rate, wherein the plurality of biomarkers include:
• (a) a first urine biomarker that is a fragment of alpha-1 antitrypsin selected from the group consisting of (i) KGKWERPFEVKDTEEEDF (SEQ ID NO:3),
• (ii) MIEQNTKSPLFMGKVVNPTQK (SEQ ID NO:4),
• (iii) EDPQGDAAQKTDTSHHDQDHPTFNKITPNLAE (SEQ ID NO:5), and
• (iv) EDPQGDAAQKTDTSHHDQDHPTFNKITPNLAEFA (SEQ ID NO:6);
• and
• (b) one or more biomarkers selected from the group consisting of (i) a second urine biomarker that is precursor alpha-2-HS-glycoprotein, VVSLGSPSGEVSHPRKT (SEQ ID NO:1), or MGVVSLGSPSGEVSHPRKT (SEQ ID NO:2), (ii) a third urine biomarker that is alpha-1 acid glycoprotein or GQEHFAHLLILRDTKTYMLAFDVNDEKNWGLS (SEQ ID NO:7), (iii) a fourth urine biomarker that is osteopontin or YPDAVATWLNPDPSQKQNLLAPQNAVSSEETNDFKQETLPSK (SEQ ID NO:8), and (iv) if the optional serum sample is obtained, a serum biomarker that is osteopontin or YPDAVATWLNPDPSQKQNLLAPQNAVSSEETNDFKQETLPSK (SEQ ID NO:8);
• calculating a disease score based on the levels of the plurality of biomarkers, and optionally, the one or more clinical factors;
• and
• assessing the diabetic nephropathy stage of the subject based on the disease score as compared to pre-determined cutoff values that indicate different diabetic nephropathy stages, wherein the levels of the plurality of biomarkers are determined with antibodies that specifically bind to the biomarkers.

A method for monitoring diabetic nephropathy progress in a subject, comprising:

• obtaining a first urine sample, and optionally, a first serum sample, from a subject suspected of having diabetic nephropathy;
• obtaining a second urine sample, and optionally, a second serum sample, 2 weeks to 12 months later;
• determining the level of each of a plurality of biomarkers in the first and second samples, and optionally, one or more clinical factors, the one or more clinical factors being selected from the group consisting of age, gender, HbA1 c, albumin/creatinine ratio, and glomerular filtration rate, wherein the plurality of biomarkers include:
• (a) a first urine biomarker that is a fragment of alpha-1 antitrypsin selected from the group consisting of (i) KGKWERPFEVKDTEEEDF (SEQ ID NO:3),
• (ii) MIEQNTKSPLFMGKVVNPTQK (SEQ ID NO:4),
• (iii) EDPQGDAAQKTDTSHHDQDHPTFNKITPNLAE (SEQ ID NO:5), and
• (iv) EDPQGDAAQKTDTSHHDQDHPTFNKITPNLAEFA (SEQ ID NO:6);
• and
• (b) one or more biomarkers selected from the group consisting of (i) a second urine biomarker that is precursor alpha-2-HS-glycoprotein, VVSLGSPSGEVSHPRKT (SEQ ID NO:1), or MGVVSLGSPSGEVSHPRKT (SEQ ID NO:2), (ii) a third urine biomarker that is alpha-1 acid glycoprotein or GQEHFAHLLILRDTKTYMLAFDVNDEKNWGLS (SEQ ID NO:7), (iii) a fourth urine biomarker that is osteopontin or YPDAVATWLNPDPSQKQNLLAPQNAVSSEETNDFKQETLPSK (SEQ ID NO:8), and (iv) if the optional first and second serum samples are obtained, a serum biomarker that is osteopontin or YPDAVATWLNPDPSQKQNLLAPQNAVSSETNDFKQETLPSK (SEQ ID NO:8);
• calculating a first disease score and a second disease score based on the levels of the plurality of biomarkers in the first and second samples, respectively, and optionally, on the one or more clinical factors;
• and
• assessing disease progress in the subject, wherein the second disease score being greater than the first disease score is indicative of diabetic nephropathy exacerbation, wherein the levels of the plurality of biomarkers are determined with antibodies that specifically bind to the biomarkers.