OBJECTIVETo investigate the effects of Xinfeng Capsule (XFC) on pulmonary function and related mechanism in adjuvant-induced arthritis (AA) rats.

METHODSThe rats were randomly divided into five groups: normal control (NC), model control (MC) groups, methotrexate (MTX), tripterygium glycosides tablet (TPT) and Xinfeng capsule (XFC) treatment groups. The adjuvant-induced arthritis model was established by intracutaneous injection of 0.1 mL Freund ' s complete adjuvant in the right paw of rats; the drugs were given 19 d after model establishment. The toe swelling degree (E), arthritis index (AI), pulmonary function, peripheral blood Treg levels, pathological changes of lung tissue and expression of Foxp3, TGF-β1, Smad3, Smad7 proteins in lung tissue were measured 30 d after drug administration.

RESULTSCompared to NC group, the levels of E, AI, alveolitis score, TGF-β1 and Smad3 were significantly increased (P <0.05 or P <0.01); maximum expiratory flow 25% of vital capacity (FEF25),50% maximal expiratory vital capacity flow (FEF50), maximum expiratory flow at 75% of vital capacity (FEF75), maximum mid-expiratory flow (MMF), force peak expiratory flow (PEF), CD4+ CD25+ Treg, Foxp3 and Smad7 were significantly decreased in MC group (P <0.05 or P < 0.01). Compared to MC group,the expression of E, AI, TGF-β1 and Smad3 were reduced, while FEF50, FEF75, MMF, PEF, Treg, Foxp3 and Smad7 were elevated in XFC group (P <0.05 or P <0.01). Compared to XFC group, the level of body mass,FEF25,FEF50, FEF75, MMF and Treg were lower in MTX and TPT groups (P <0.05 or P <0.01).

CONCLUSIONThere are inflamed joints and reduced pulmonary function in rats of adjuvant-induced arthritis. XFC can inhibit paw edema degrees, reduce arthritis response, and improve pulmonary function, which is associated with up-regulating expression of Treg and Foxp3, down-regulating the expression of TGF-β1 and adjusting TGF-β1/Smads signal pathway.