Dietary Flavonoid Apigenin is not Effective in Preventing Development of a Bleomycin-Induced Murine Model of Scleroderma

Abstract

Objective. Systemic sclerosis is a connective tissue disease characterized by vasculopathy, excessive accumulation of extracellular matrix, and fibrosis of the skin and internal organs. The dietary flavonoid apigenin has been shown to reduce expression of the myofibroblast phenotype and to inhibit contraction of collagen gels. We investigated the effect of apigenin on the prevention and treatment of a modified bleomycin-induced animal model of scleroderma. Methods. Recently, we successfully induced scleroderma by weekly subcutaneous injections of bleomycin using a thermo-reversible combination gel composed of low molecular weight methylcellulose. A weekly subcutaneous injection of methylcellulose gel loaded with bleomycin induced focal skin fibrosis on the back skin and fibrotic phenotype of lung tissue in mice. The histologic examination of skin and lungs, collagen assay of lungs, and expression of connective tissue growth factor were investigated. Results. Daily intra-peritoneal injection of 1.0 mg/kg or 2.5 mg/kg of apigenin starting a week before the bleomycin injections failed to prevent the development of skin fibrosis and reduce the fibrotic phenotypes of skin and lung tissue. Conclusion. Although some in vitro experiments have supported a potential role of apigenin in the treatment of fibrosis, dietary flavonoid apigenin is not effective in preventing development of a bleomycin-induced murine model of scleroderma.