Background: Graft-versus-host disease (GVHD) is an important complication occurring after hematopoietic stem-cell transplantation (HSCT). Animal model studies have shown the involvement of the Fas (APO-1/CD95)/Fas-Ligand pathway in GVHD pathogenesis, but its association with cutaneous GVHD in human remains to be established.
Methods: In the present study, Fas involvement in skin damage was assessed using a human skin explant model of GVHD. Fas and FasL expression were measured by immunohistochemistry and blockade of Fas pathway was investigated using an antagonistic anti-human Fas monoclonal antibody. In addition, levels of soluble Fas (sFas) were determined in the serum of patients receiving allogeneic HSCT with and without GVHD.
Results: The results showed that Fas up-regulation in the epithelium of human skin explants correlated with graft-versus-host reaction (GVHR) in the skin explant model (P<0.001). Decreased GVHR grades were observed by using a Fas blocking monoclonal antibody. Levels of sFas were increased post-HSCT (P<0.001) but rather than being associated with the severity of GVHD, sFas levels differed with the conditioning treatments the patients received before the HSCT.
Conclusions: Higher GVHR grades were associated with increased Fas expression in the epithelium of the skin explants. In addition, by blocking Fas-mediated apoptosis, the GVHR grades were decreased. Our study thus shows the involvement of Fas in cutaneous GVHD damage, and supports the potential use of Fas as a therapeutic target.