The Expression of Heat Shock Proteins 27 and 70 in Lupus Nephritis

Abstract

Background: Heat shock protein (HSP ) up-regulation is a cytoprotective response following stress insults (toxic, ischemic, inflammatory and oxidative). Ob ject ive: To study the localization of HSP 27 and HSP 70 in the renal tissue of patients with lupus nephritis (LN) and correlate our findings with the severity of histological involvement (activity and chronicity indices) and the degree of renal function impairment. Pat ients and Methods: Seventy patients with LN (diffuse proliferative n=31, focal proliferative n=20, and membranous n=19) were included in the study. The distribution of HSP 27/HSP 70 was studied by immuno-histochemistry in renal biopsy sections. A double staining method for vimentin, a-smooth muscle actin, CD 34 and CD 68 (+) cells were performed to identify the type of glomerular cells expressing HSP s. The severity of immunostaining for HSP 27/70 was evaluated semiquantitively. Results : HSP 27 and HSP 70 were identified within the cytoplasm of tubular epithelial cells of all patients. Increased HSP 27 expression was noted within intrinsic glomerular cells in diffuse lupus nephritis whereas no glomerular expression was observed in focal proliferative and membranous LN. A significant positive correlation was found between HSP 27 expression in diffuse proliferative nephritis and the activity and total (activity + chronicity) indices. The severity of histological involvement was also related to the degree of renal function impairment. Conclusions: Up-regulation of heat shock protein expression was identified in patients with various types of LN, especially those with diffuse proliferative nephritis. The severity of HSP 27 expression was related to the activity and total indices. These results suggest a possible defensive role for HSP 27 in severe lupus nephritis.