<b><i>Objectives:</i></b> The interleukin-6 (IL-6)-mediated signaling pathway plays an essential role in the development of rheumatoid arthritis. LMT-28 suppresses the activation of the IL-6-mediated signaling by direct targeting of gp130. Although LMT-28 and metformin both possess anti-inflammatory activity, the beneficial effect of LMT-28 and metformin combination on a collagen-induced arthritis (CIA) model has not yet been investigated. This study aimed to investigate the anti-inflammatory effect and mechanism of a combination of LMT-28 and metformin in a CIA model. <b><i>Methods:</i></b> In MH7A cells, cell proliferation and the IL-6-mediated signaling pathway following administration of LMT-28 and metformin combination was analyzed through MTT assay and Western blotting. The level of T helper 17 (Th17) cell differentiation from CD4⁺ T cells was analyzed in mouse splenocytes and human peripheral blood mononuclear cells. Arthritis score, incidence rate, inflammatory cytokine, and T-cell subsets were measured in CIA mice following administration of LMT-28 and metformin combination. <b><i>Results:</i></b> Combination treatment with LMT-28 and metformin diminished proliferation of MH7A cells and IL-6-mediated gp130, STAT3, and ERK signaling more than in individual treatments. Furthermore, the differentiation of CD4⁺ T cells into Th17 cells was attenuated more by combination treatment with LMT-28 and metformin than individual treatments. The combination of LMT-28 and metformin ameliorated the arthritic score better than individual treatments. The combination significantly reduced tumor necrosis factor and IL-6 levels in the sera and had an anti-inflammatory effect on the distribution of Treg/Th17 cells in the lymph nodes. <b><i>Conclusion:</i></b> Combination treatment with LMT-28 and metformin significantly ameliorates arthritic symptoms in CIA by suppressing Th17 differentiation and IL-6 signaling.

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Background: Combination therapy has been administered to patients with chronic or complex diseases due to its improved therapeutic effects compared with the results of monotherapy. Due to the pleiotropic effects of statins and antiplatelets, these drugs have been studied in combination with other drugs, but not all combinations exerted obvious beneficial effects compared with individual drugs. In this study, we aimed to compare the anti-inflammatory effects of 4 different combination therapies of statins and antiplatelets on the tumor necrosis factor (TNF)-mediated inflammation in vivo. Methods: Mice were orally administered cilostazol plus pravastatin (CILOP) or cilostazol plus rosuvastatin (CILOR), clopidogrel plus pravastatin (CLOP), or clopidogrel plus rosuvastatin (CLOR); then, acute inflammation was induced by the injection of lipopolysaccharide (LPS) or TNF. Serum TNF levels, macrophage accumulation in the lesioned aortas, and mouse mortality were observed to be comparable to the anti-inflammatory effects of the combination therapies. Results: In mice with LPS-induced inflammation, CILOP and CILOR substantially reduced macrophage infiltration of aortic lesions and the serum TNF levels compared with CLOP and CLOR. Moreover, among the 4 combinations, CILOP significantly improved the survival rate of mice with TNF-mediated acute lethal inflammation. Conclusions: The combination therapy comprising cilostazol and statins, particularly pravastatin, exerted the best anti-TNF effect compared with clopidogrel and statin therapy; thus, a suitable combination therapy, such as CILOP, can be a potential remedy to cure TNF-related diseases.