Morphometric and immunohistochemical insight into focal segmental glomerulosclerosis in obese and non-obese patients

A number of studies have reported an alarming increase in the incidence of obesity related-glomerulopathy. Focal segmental glomerulosclerosis has recently been shown to be key lesion leading to end-stage renal disease in these cases.

Nineteen patients with obesity-related focal segmental glomerulosclerosis (O-FSGS) and 16 with idiopathic focal segmental glomerulosclerosis (I-FSGS) were examined by percutaneous renal biopsy. Glomerular and interstitial parameters in O-FSGS and I-FSGS were compared morphometrically as well as immunomorphological study was done to evaluate immunohistochemical profile of TGFbeta- 1, monocytes/macrophages, T lymphocytes and alpha-SMA in these groups.

The total glomerular cells, mesangial areas, glomerular alpha-SMA staining, glomerular monocytes/macrophages and glomerular T-cells were in IFSGS increased in comparison with O-FSGS, most of them significantly, whereas total glomerular area was significantly greater in O-FSGS patients. The tubular immunoexpression of TGF-beta-1, interstitial volume and interstitial alpha-SMA staining were significantly increased in I-FSGS cases in comparison with O-FSGS group, but interstitial CD68+ and CD3+ cells did not differ significantly. Moreover, we found in both O-FSGS and I-FSGS groups significant positive correlations between glomerular immunoexpression of alpha-SMA and glomerular CD 68+ cells, tubular immunoexpression of TGF-beta-1 and interstitial immunoexpression of alpha-SMA as well as tubular immunoexpression of TGF-beta-1 and interstitial volume. Negative correlation between tubular immunoexpression of TGF-beta-1 and interstitial CD3+ cells was significant only in IFSGS group.

Our morphometric and immunohistochemical study suggests that O-FSGS and I-FSGS are separate morphological entities whereas mechanisms of glomerular and interstitial injury in these cases seem to be rather similar.