Methods, products and treatments for diabetes

#Diabetes Mellitus (diabetes) is a leading cause of morbidity and mortality in the adult population. This is primarily because diabetic patients tend to develop vascular complications that involve the kidneys (diabetic nephropathy), the retina (diabetic retinopathy), as well as large and small blood vessels in other organs (macro- and micro-vascular disease) including nerves (diabetic neuropathy). It is well established that the vascular complications of diabetes are caused by elevated blood glucose levels over long periods of time. Elevated blood glucose levels affect proteins by a process known as glycation. Different “glycated” proteins have been identified in diabetic subjects, including albumin, hemoglobin and others. Measurement of the extent of protein “glycation” of certain proteins is considered a valuable clinical tool to assess long term glycemic control and thereby the efficacy of diabetes treatment.

#Glycation, the non-enzymatic attachment of glucose to proteins, is considered a major pathophysiological mechanism causing tissue damage in diabetic subjects. Glycation involves the reaction of glucose and/or other reducing sugars with amino groups in proteins resulting in the formation of a Schiff base or aldimine. This labile adduct can tautomerize via the Amadori rearrangement to the more stable ketoamine. The function of the glycated protein may be impaired, depending on the location of the amino group(s) affected. For example, amino-terminal glycation of the β-chains of hemoglobin gives rise to the glycated hemoglobins (HbA1) in which responsiveness to 2,3-diphosphoglycerate is decreased and oxygen affinity increased. Glycation of the major thrombin inhibitor of the coagulation system, antithrombin III, decreases its affinity for heparin, and has been postulated to contribute to the hypercoagulable state associated with diabetes.

#Hemoglobin glycation and thrombin inhibitor glycation do not account for the vascular complications of diabetes. The mechanism which results in such complications remains unknown.

#FIG. 1 is a schematic of a kit according to the invention.

#FIG. 2 is a graph indicating CD59 activity as a percent of control activity for a cell suspension of GPE incubated with purified CD59 previously exposed for different time intervals to the glycating sugars glucose (open triangles, 0.5M) or ribose (open squares; 0.5M), or to non-glycating sorbitol (closed squares, 0.5M). Data points represent the mean of triplicate determinations (SEM are smaller than data points). Figure is representative of experiments run three times with comparable results. Inset shows the number of CD59 molecules incorporated per GPE as determined with 125I-CD59 before (C) and after (R) glycation with ribose.

#FIG. 3A is an image of a western blot and FIGS. 3B and 3C are graphs. Panel (3A) indicates expression of wild-type (WT) CD59, and CD59 mutants Gln-41 and Gln-44 in CHO cells as confirmed by SDS-PAGE followed by Western blot analysis of CHO cell extracts using the YTH 53.1 monoclonal antibody, Vector (closed square); WT (open square); CD59-Gln-41 (open triangle); Gln-44 (open circle). Panel (3B) indicates activity of WT and mutant CD59s tested in the GPE hemolytic assay before and after glycation with ribose for the time intervals indicated. Panel (3C) indicates CD59 and mutant CD59 activity as a percent of control activity for a cell suspension of GPE incubated with purified WT CD59 (open squares) and Gln-41 (open triangles), and Gln-44 (open circles) following incubation with the glycating sugar ribose. Data points represent the mean of triplicate determinations (SEM are smaller than the data points). The figure is representative of experiments run three times with comparable results.

#The invention disclosed herein describes novel methods and compositions for detecting and measuring K41-glycated CD59 levels, particularly as they relate to glycemic levels. The discovery that CD59 is glycated facilitates analysis of diseases in which the amount of CD59 glycation differs from normal levels. For example, it has been discovered that the level of glycation of CD59 is elevated in diabetes. Thus, onset, progression and/or regression of diabetes or other diseases can be monitored by monitoring levels of glycated CD59 in a subject. It also has been determined that CD59 is present in urine. Therefore, the measurement can be done in urine without requiring a blood sample.

#In addition, in contrast to markers of glycation such as hemoglobin, glycation of CD59 is believed to be involved in the pathogenesis of the vascular complications of diabetes. Accordingly, clinical evaluation of K41-glycated CD59 in urine is a direct measure for vascular damage induced by glycation. Without wishing to be bound by any particular theory, it is believed that patients with abnormally high levels of K41-glycated CD59 in urine will either have or will be more prone to develop vascular complications of diabetes.

#As used herein, CD59 (also known as membrane inhibitor of reactive lysis [MIRL], protectin, HRF20 and H19) and K41-glycated CD59 are a polypeptide having substantial nucleotide and/or amino acid sequence identity of Accession No. M95708 (Davies, A., et al., Journal J. Exp. Med. 170 (3), 637-654 (1989)).