Immunoglobulin A nephropathy in patients with non-insulin dependent diabetes mellitus

Defining the spectrum of immunoglobulin A-dominant/codominant glomerular deposition in diabetic nephropathy

In patients with diabetic nephropathy (DN), the spectrum of immunoglobulin A (IgA)-dominant/codominant glomerular deposition (IgAGD) has not been addressed in the literature. The aim of our study is to detail the clinicopathological and outcome findings in patients with DN and IgAGD. Our database was retrospectively searched over a 10-year period for patients with DN and IgAGD. A total of 132 patients were included in the study, 55 with outcome data. All cases were reviewed by light microscopy, immunofluorescence, and electron microscopy. Mean age was 59 ± 13 years, with a 2:1 male-to-female ratio. Indications for biopsy were often multiple, with proteinuria/nephrotic syndrome and acute renal failure being the most common. All patients showed IgAGD and mesangial deposits by electron microscopy. Seventy-three (55.3%) patients had no proliferative glomerular changes and no clinical history of infection and were most consistent with IgA nephropathy on DN, whereas 19 (14.4%) showed proliferative glomerular changes, had a history of infection, and were most consistent with IgA-dominant infection-associated glomerulonephritis. Forty (30.3%) patients showed a mixture of these findings and did not fit into either category. Patients with a mean of 42 (2-120 range) months of follow-up showed an overall poor prognosis, with 59% of all respondents proceeding to renal replacement therapy or death (RRT/D) over an average of 23 (range, 4-54) months. Progression to RRT/D was most frequent in those most consistent with IgA-dominant infection-associated glomerulonephritis (71%), and by multivariate analysis, only advanced Tervaert morphologic classification (classes III and IV) was associated with progression to RRT/D.

Diabetic nephropathy: of mice and men

Accumulating evidence supports intrinsic genetic susceptibility as an important variable in the progression of diabetic nephropathy in people. Mice provide an experimental platform of unparalleled power for dissecting the genetics of mammalian diseases; however, phenotypic analysis of diabetic mice lags behind that already established for humans. Standardized benchmarks of hyperglycemia, albuminuria, and measurements of renal failure remain to be developed for different inbred strains of mice. The most glaring deficiency has been the lack of a diabetic mouse model that develops progressively worsening renal insufficiency, the sine qua non of diabetic nephropathy in humans. Differences in susceptibility of these inbred strains to complications of diabetes mellitus provide a possible avenue to dissect the genetic basis of diabetic nephropathy; however, the identification of those strains and/or mutants most susceptible to renal injury from diabetes mellitus is lacking. Identification of a mouse model that faithfully mirrors the pathogenesis of DN in humans will undoubtedly facilitate the development of new diagnostic and therapeutic interventions.

Mouse models of diabetic nephropathy

Mice provide an experimental model of unparalleled flexibility for studying mammalian diseases. Inbred strains of mice exhibit substantial differences in their susceptibility to the renal complications of diabetes. Much remains to be established regarding the course of diabetic nephropathy (DN) in mice as well as defining those strains and/or mutants that are most susceptible to renal injury from diabetes. Through the use of the unique genetic reagents available in mice (including knockouts and transgenics), the validation of a mouse model reproducing human DN should significantly facilitate the understanding of the underlying genetic mechanisms that contribute to the development of DN. Establishment of an authentic mouse model of DN will undoubtedly facilitate testing of translational diagnostic and therapeutic interventions in mice before testing in humans.