Expression of heat shock protein 60 in cutaneous lichen planus:an immunohistochemical study

Background Lichen planus (LP) is a chronic inflammatory papulosquamous skin disease recognized as a T cell-mediated disease. Heat shock proteins (HSPs) are expressed by most living cells, and they play fundamental role in many biological processes. The expression of certain HSPs in oral LP was reported in many studies. However, the expression of certain HSPs in cutaneous LP was reported in only in few studies. Objective To investigate the expression of HSP60 in lesions of cutaneous LP and compare it with normal skin to know if it has a role in LP pathogenesis or not. Method Forty LP patients and 10 controls of apparently normal skin were studied. Skin biopsies were taken for hematoxylin and eosin examination and for the immunohistochemistry using mouse anti-HSP60 monoclonal antibody. An immunoreactivity intensity distribution index (IRIDI) was calculated for each case and control. Results The mean total IRIDI scores for HSP60 expression in epidermal layers and cells of the inflammatory infiltrate (mostly lymphocytes) of cutaneous LP showed statistically significantly increase than those of normal skin (P =0.001). The mean IRIDI score for HSP60 expression in basal and suprabasal layers of LP patients also showed statistically significantly increase than those of normal skin (P= 0.001 and P =0.05, respectively). The mean IRIDI score for HSP60 expression in the superficial epidermal layer of LP patients was statistically lower than that of normal skin (P= 0.001). A positive statistically significant correlation was found in LP patients between the mean IRIDI score for the dermal infiltrate and the mean total epidermal IRIDI score. Conclusion HSP60 could have a role in cutaneous LP pathogenesis.