The Role of Wnt/β-catenin Signaling Pathway in Vascular Remodeling in Bleomycin-induced Systemic Sclerosis Mouse Model / 中国生物化学与分子生物学报

ABSTRACT

Systemic sclerosis (SSc) is a chronic autoimmune disease that can involve multiple organs throughout the body. It is characterized by extensive vascular disease and fibrosis of the skin and internal organs, but its mechanism is still unclear. Studies have confirmed that the Wnt pathway is involved in SSc fibrosis, but its pathological role in vascular lesions has not been reported. In this study, the bleomycin (BLM)-induced SSc mouse model was used to investigate the role of Wnt pathway in SSc cutaneous vascular lesions. Eighteen BALB/C mice were randomly divided into control, model and treatment groups. The control group of mice was injected with PBS 100 μL/d. The model group was injected with BLM 100 μL/d at a concentration of 1 mg/mL. The treatment group of mice received injection of BLM 100 μL as the model group of mice and retroperitoneal injection of iCRT3 (Wnt and beta-catenin inhibitors) 5 mg/kg/d. Mice were sacrificed on day 28. The thickness of dorsal dermis and epidermis in the model group induced by BLM was significantly higher than that in the control group (P <0. 05). The skin appendages such as sebaceous glands and hair follicles in the model group were significantly reduced. At the same time, the thickness of fat layer became thinner and surrounded by fibrous tissue, and the collagen deposition in the model group was higher than that in the control group. It was identified at the histological level by immunohistochemical staining that α-SMA expression in model group and treatment group α-SMA is highly expressed in skin tissues, and the positive expression of α-SMA around blood vessels was significantly higher than that in the control group. In addition, the expression of IL-6 and IL-17 in serum of model group was significantly higher than that in control group (P<0. 05), and the expression of IL-6 and IL-17 in serum of treatment group was significantly lower than that in model group (P<0. 05). Furthermore, q-PCR analysis showed that the mRNA levels of β-catenin in the skin microvessels of the mice were higher in the model and the treatment groups as compared with the control group. The protein levels of Wnt5A, β-catenin, α-SMA and col1A1 were analyzed by Western blotting and results showed that the levels of fibrosis-related proteins, α-SMA and col1A1, were increased in the model group injected with BLM as compared with the control group (P<0. 05), whereas iCRT3 treatment attenuated the upregulation of α-SMA and col1A1 induced by BLM in the treatment group (P<0. 05). The levels of Wnt pathway-related proteins β-catenin and Wnt5A were significantly increased in the model group as compared with the control (P<0. 05). This study suggests that BLM can successfully induce the skin phenotype of mice with systemic sclerosis. Abnormal activation of Wnt signaling pathway is involved in BLM-induced skin microangiopathy in mice with scleroderma, and the specific Wnt pathway inhibitor iCRT3 can reduce BLM-induced scleroderma. The expression of α-SMA and col1A1 proteins in mouse skin microvessels can improve the microvascular lesions of mouse skin. Inhibition of Wnt pathway may directly or indirectly down-regulate the abnormal expression of cytokines IL-6 and IL-17, and interfere with BLM-induced progression of vascular lesions in mice.