Myofibroblast involvement in tubular basement membrane remodeling in type II diabetic nephropathy

Diabetic nephropathy is always accompanied by tubulointerstitial damage. The mechanisms and the cells involved are not entirely clarified. The damaged tubules may regenerate or undergo necrosis or apoptosis. The purpose of this work was to investigate the structural transformations of both interstitial cells and extracellular matrix of the kidney stromal area in patients with type II diabetes mellitus associated with diabetic nephropathy. Tubulointerstitial fibrosis is characterized by loss of renal tubules and interstitial capillaries and the accumulation of extracellular matrix proteins. Tubular basement membranes were found to be a target of the remodeling process of the stromal area. Thickening, splitting and duplication were the main lesions of these membranes. Much attention has been focused on the importance of myofibroblasts in the progression of renal fibrosis. The results represent strong arguments for a direct involvement of myofibroblasts in the process of renal interstitial remodeling, tubular basement membrane thickening, and stromal fibrosis in the late stages of diabetic nephropathy.