Increased Hedgehog signaling in murine sclerodermatous cGVHD. Shh, Gli-1, and Gli-2 were detected by immunohistochemistry in skin biopsies of syngeneic controls (synBMT), sham-treated mice receiving alloBMT (alloBMT), and recipients treated with LDE223, either in preventive or therapeutic regimens (n = 6 each). Fibroblasts were identified by double staining for vimentin. Representative images of the treatment groups and the control groups are shown at 1000-fold magnification. (A) Shh expression was strongly increased 42 days after alloBMT compared with syngeneic controls. Consistent with the proposed mechanism of action, LDE223 did not affect the expression of Shh in mice receiving alloBMT. (B-C) Gli-1 and Gli-2 signaling was activated in skin of mice receiving alloBMT with increased staining for Gli-1 (B) and Gli-2 (C) compared with syngeneic controls. Preventive treatment as well as treatment of clinically manifest sclerodermatous cGVHD with LDE223 diminished the expression of both Gli-1 and Gli-2. synBMT indicates syngeneic controls; and alloBMT, mice receiving alloBMT.