Autologous hematopoietic stem cell transplantation reverses skin fibrosis but does not change skin vessel density in patients with systemic sclerosis.

Hematopoetic stem cell transplantation (HSCT) improves survival in patients with severe systemic sclerosis (SSc) by resetting the immune system. We studied how HSCT acts on the key SSc skin pathology findings (fibrosis and vascularization). In mean, 3 skin punch biopsies per patient (range 2-6) were analyzed from 13 patients (5 females) with severe diffuse SSc before and up to 96 months after HSCT. Fibrosis of the four skin layers was graded semi-quantitatively and an overall fibrosis score was then calculated. Vessel numbers and calibers were assessed in the superficial and deeper dermis after immune-staining for endothelial antigens (CD31, VE-cadherin and vWF). The median age of patients at HSCT was 47 (24-64) years. The overall median modified Rodnan skin score decreased from 24 to 10 (P=0.003) at first follow-up within a median of 9 (6-36) months after HSCT as did the histological skin score (P=0.03). The modified Rodnan skin score and the fibrosis score correlated positively (r=0.589, P<0.001). The vessels density did not significantly change after HSCT nor did the expression of the tested endothelial markers. Although improving skin fibrosis in patients with SSc, HSCT does not alter vessel density within skin biopsies.

Partial reconstitution of cutaneous microvessels in long-term survivors after allogeneic bone marrow transplantation.

BACKGROUND: Graft-versus-host disease (GVHD) is a major complication after allogeneic hematopoietic stem cell transplantation (HSCT) and skin is involved in acute and chronic disease. Immune-mediated vessel attack and subsequent microvessel loss have been observed in skin of patients with chronic GVHD. OBJECTIVES: To test whether long-term survivors (LTS) after allogeneic HSCT without cutaneous GVHD show signs of persistent vascular remodeling. METHODS: Microvessels in skin biopsies were investigated in a cohort of 32 LTS with a median follow-up of 17 years (range 11-26). Five were currently classified as having chronic GVHD other than skin involvement. RESULTS: LTS showed no significant difference in median microvessel density and relative vessel size distribution pattern compared to healthy controls. Past experience of GVHD and current status of chronic GVHD other than skin involvement had no impact on vessel density. In contrast, recipients with chronic cutaneous GVHD of sclerotic type and patients with lichen sclerosus have significant microvessel loss in the upper dermis. CONCLUSION: The complex therapy of allogeneic HSCT had no sustained effect on the microvascular architecture of LTS when clinicopathological evidence of cutaneous GVHD is absent. Microvascular remodeling as observed during chronic GVHD recovers completely after resolution of chronic cutaneous GVHD.

Gli2 upregulates cFlip and renders basal cell carcinoma cells resistant to death ligand-mediated apoptosis.

Mutations in the Hedgehog signaling pathway is responsible for the formation of various cancers, including some forms of basal cell carcinoma (BCC). Uncontrolled Hedgehog signaling leads to overexpression of the zinc-finger Gli transcription factors, among which Gli2 plays a central role. We found that high Gli2 expression induced the concomitant high expression of the caspase 8 inhibitor, cFlip, and thereby counteracts death-ligand-mediated apoptosis. By investigating the cFlip promoter, Gli2 binding sites were identified and confirmed. Gli2 gene silencing by RNA interference broke the apoptosis resistance via cFlip downregulation. The direct functional connection between Gli2 and cFlip was not only demonstrated in a keratinocytic cell line but also in BCC tissue. As cFlip and Bcl-2 are highly expressed in BCCs, as a consequence of high Gli2 expression, this may explain the marked resistance of the tumor to the extrinsic and intrinsic apoptotic pathway. We could now demonstrate that Gli2 gene silencing in BCC tissues made the tumor sensitive to TRAIL (tumor necrosis factor-related apoptosis-inducing ligand)-mediated cell death by downregulating cFlip. As Gli2 silencing does not only downregulate cFlip, but also Bcl-2, Gli2 could be a key target for a novel therapeutic approach in tumors with dysregulated Hedgehog signaling.