Inhibition of Collagen Synthesis and Changes in Skin Morphology in Murine Graft-Versus-Host Disease and Tight Skin Mice: Effect of Halofuginone

Abstract

The effect of halofuginone, a plant alkaloid known to inhibit collagen type I synthesis, on skin collagen content and skin morphology was evaluated in two in vivo models of scleroderma: the murine chronic graft-versus-host disease (cGvHD) and the tight skin mouse. Skin collagen was assessed by hydroxyproline levels in skin biopsies and by immunohistochemistry using anti-collagen type I antibodies. Daily intraperitoneal injections of halofuginone (1 microgram/mouse) for 52 d starting 3 d before spleen cell transplantation, abrogated the increase in skin collagen and prevented the thickening of the dermis and the loss of the subdermal fat, all of which are characteristic of the cGvHD mice. Halofuginone had a minimal effect on collagen content of the control mice. The halofuginone-dependent decrease in skin collagen content was concentration-dependent and was not accompanied by changes in body weight in either the cGvHD or the control mice. Injections of halofuginone (1 microgram/mouse) for 45 d caused a decrease in the collagen content and dermis width in tight skin mice, but did not affect the dermis width of control mice. Collagen content determination from skin biopsies confirmed the immunohistochemical results in the same mice. The low concentration of halofuginone needed to prevent collagen deposition in fibrotic skin without affecting body weight suggests that halofuginone may serve as a novel and promising anti-fibrotic therapy.

Halofuginone to Prevent and Treat Thioacetamide–Induced Liver Fibrosis in Rats

“…3 and 4). These results are in agreement with our previous observations that prolonged halofuginone treatment may resolve existing fibrosis in the TSK mice 29 and in a cGvHD patient. 35 Halofuginone treatment probably perturbs the balance between synthesis and degradation of collagen.…”

“…28 In animal models in which fibrosis was induced, halofuginone prevented the increase in collagen synthesis and collagen ␣1(I) gene expression. These models included mice afflicted with cGvHD, 29 rats with pulmonary fibrosis after bleomycin treatment, 30 and rats developing adhesions after surgery in tendons, 31 the abdomen, 32 and uterine horns. 33 In liver, halofuginone prevented collagen type I gene expression in dimethylnitrosamine-induced cirrhosis in rats.…”

“…34 In addition to its ability to prevent fibrosis by inhibiting the collagen ␣1(I) gene expression, halofuginone treatment caused an attenuation of the collagen already deposited in skin. This may be possible by altering the balance between synthesis and degradation of collagen type I as shown in tight skin (Tskϩ) mice 29 and in a cGvHD patient. 35 The goal of the present study was to evaluate the possibility of using halofuginone both to prevent and to treat hepatic fibrosis.…”

Chronic graft-versus-host disease: is there an alternative to the conventional treatment?

“…78 This drug was given daily to mice 3 days after hematopoietic stem cell transplantation. An absence of increased cutaneous collagen disposition and the prevention of dermal thickening were observed.…”

Halofuginone inhibits tumor growth in the polyoma middle T antigen mouse via a thrombospondin-1 independent mechanism

“…4 In animal models of fibrosis in which excess collagen is the hallmark of the disease, administration of halofuginone prevented the increase in collagen α1(I) gene expression and collagen synthesis. These models included mice afflicted with cGvHD and tight skin (Tsk+) mice, 5,6 rats with pulmonary fibrosis, 7 rats that had developed adhesions at various locations, [8][9][10] rats with liver fibrosis, [11][12][13] and mice with radiation-induced fibrosis. 14 Clinical efficacy was demonstrated by topical dermal halofuginone administration in a cGvHD patient 15 and in a scleroderma phase II clinical study.…”