Therapeutic effects of hypoxia-inducible factor-1α siRNA on collagen-induced arthritis in mice and its inhibitory effects on M1 macrophages / 中华微生物学和免疫学杂志

ABSTRACT

Objective:To investigate the therapeutic effects of a small interfering RNA (siRNA) targeting hypoxia inducible factor-1α (HIF-1α) on collagen-induced arthritis (CIA) in mice and to analyze the possible mechanism at the macrophage level.Methods:DBA/1 mice were injected with bovine type Ⅱ collagen to establish the CIA model. Then, they were injected with HIF-1α-siRNA adenovirus or negative control adenovirus through tail vein once a week for four weeks. This study included four groups control group, CIA model group, negative control group and HIF-1α-siRNA group. Mouse bone marrow-derived macrophages (BMDMs) were isolated and cultured. The relative expression of CD206 and arginine (Arg) at mRNA level in mouse BMDMs was detected by RT-PCR. The proportions of F4/80 + CD16/32 + M1 and F4/80 + CD206 + M2 macrophages in spleen and thymus were detected by flow cytometry. Pathological changes in the ankle joint of mice were observed using HE staining. Immunohistochemistry was used to detect the expression of macrophages and the subsets in mouse synovial tissues. Results:(1) Compared with the control group, the CIA model group showed decreased expression of CD206 at mRNA level in BMDMs, but increased expression of Arg at mRNA level ( P<0.01). HIF-1α-siRNA increased the expression of CD206 at mRNA level ( P<0.05) and reduced the expression of Arg at mRNA level in BMDMs of mice with CIA ( P<0.01). (2) Compared with the control group, the mice in the CIA model group had increased proportions of F4/80 + CD16/32 + M1 macrophages in splenocytes and thymocytes ( P<0.05), but decreased proportions of F4/80 + CD206 + M2 macrophages in thymocytes ( P<0.05). HIF-1α-siRNA could down-regulate the proportions of F4/80 + CD16/32 + M1 macrophages in splenocytes and thymocytes ( P<0.05), and up-regulate the proportions of F4/80 + CD206 + M2 macrophages in thymocytes of CIA mice ( P<0.01). (3) CIA mice had synovial hyperplasia and macrophages infiltration, especially M1 macrophages, in the ankle joint. HIF-1α-siRNA could alleviate the synovial hyperplasia and macrophage infiltration. Conclusions:HIF-1α-siRNA could alleviate macrophage infiltration and synovial hyperplasia in CIA mice through reducing the proportions of M1 macrophages in thymocytes, BMDMs and synovial tissues and increasing the proportion of M2 macrophages, suggesting that HIF-1α-siRNA could treat CIA mice by regulating the differentiation of M1 and M2 macrophages.