Preventive and Therapeutic Effects Ramulus Mori Extract on Collagen-Induced Arthritis in Mice via Suppression of Inflammatory T Cells

Abstract

We researched the preventive and therapeutic activities of the extract of Ramulus Mori (ERM) to observe its effects on collagen-induced arthritis (CIA) in mice and to explore the mechanisms of ERM in the treatment of rheumatoid arthritis (RA). We examined the in vitro levels of tumor necrosis factor α (TNF-α) released in macrophages and of interferon (IFN)-γ and interleukin (IL)-4 released in splenocytes. For in vivo experiments, we randomly divided 24 mice into four groups, after type II collagen (CII) injections and at euthanization. The levels of plasma cytokines (TNF-α, IL-6, IL-17), rheumatoid factor (RF; IgG, IgM), and anti-CII antibody were measured using ELISA kits. The number of immunocytes (CD4⁺ T cells, CD3⁺/CD69⁺ T cells, B220⁺/CD45⁺ B cells, CD11b⁺/Gr-1⁺ cells) relative to RA was calculated using flow cytometry (FACS). The articular index (AI) was recorded once a week for 4 weeks. Sections of tissues from the knee joints were stained with hematoxylin and eosin (H&E) and Masson trichrome (MT) after the mice with CIA were euthanized. ERM reduced the levels of TNF-α in macrophages and IFN-γ in spleen cells, decreased AI scores, and improved inflammation of paw joints (PJ). ERM also suppressed the number of immunocytes in peripheral blood mononuclear cells (PBMCs) and PJ, and reduced the levels of cytokines (TNF-α, IL-6, and IL-17), RF, and anti-CII antibody in the sera. TNF-α and Th1 cells play very important roles in the formation and development of RA. ERM and methotrexate notably decreased the induction of RA in the CIA mice model by reducing the levels of inflammatory cytokines and RF in the sera and suppressing the number of immunocytes among PBMCs and PJ.