OBjECTIVE:To observe the relationship between reduced pulmonary function and regulatory T cells(Tregs)and helper T cells(Th)1/Th2 drift in a rat model of adjuvant arthritis(AA),and to study the impact of Xinfeng capsule(XFC)on pulmonary function and investigate the mechanism of action.METHODS:Forty rats were randomly divided into normal control group(NC),model control group(MC),Tripterygium glycosides tablet group(TPT),and XFC group,with 10 in each.Except for the NCgroup,AA was induced in all rats by intracutaneous injection of 0.1 mL Freund’s complete adjuvant in the right paw.On the 19th day after modeling,the NC and MC groups were given physiological saline(0.9%),while the TPT and XFC groups were given TPT(10 mg/kg)and XFC(2.4 g/kg),once daily,respectively.Thirty days after administration,changes in paw swelling,arthritis index(AI),pulmonary function,levels of serumγ-interferon(IFN-γ)and interleukin(IL)-4,Tregs in peripheral blood,and IFN-γ,IL-4,Forkhead box transcription factor 3(FoxP3)in lung tissue were observed by enzyme-linked immunosorbent assay,flow cytometry,polymerase chain reaction,and western blot.RESULTS:Compared with the NC group,paw swelling,AI,IFN-γ,and Th1/Th2 were increased,and pulmonary function parameters,IL-4,FoxP3 were decreased significantly in the MC group(P<0.05 or P<0.01).Pulmonary function parameters,Treg,IL-4,FoxP3(and mRNA)were higher,and paw swelling,AI,and IFN-γ(and mRNA)were lower in the XFC group than those in the MC group.The XFC group was also much better than theTPT group in improving pulmonary function,FoxP3 mRNA,IFN-γ,IL-4,Th1/Th2,and IL-10(P<0.05 or P<0.01).CONCLUSION:Xinfeng capsule can improve pulmonary function by regulating the levels of Tregs,inhibiting the activation of Th1 to Th2 cells,inducing drift,maintaining cell immune suppression,correcting the imbalance of Th1/Th2,and reducing inflammatory mediators. OBjECTIVE: To observe the relationship between reduced pulmonary function and regulatory T cells (Tregs) and helper T cells (Th) 1 / Th2 drift in a rat model of adjuvant arthritis (AA), and to study the impact of Xinfeng capsule (XFC) on pulmonary function and investigate the mechanism of action. METHODS: Forty rats were randomly divided into normal control group (NC), model control group (MC), Tripterygium glycosides tablet group (TPT), and XFC group, with 10 in each. for the NCgroup, AA was induced in all rats by intracutaneous injection of 0.1 mL Freund’s complete adjuvant in the right paw. On the 19th day after modeling, the NC and MC groups were given physiological saline (0.9%), while the TPT and XFC Groups were given TPT (10 mg / kg) and XFC (2.4 g / kg), once daily, respectively. Thirty days after administration, changes in paw swelling, arthritis index (AI), pulmonary function, levels of serum gamma- -γ) and interleukin (IL) -4, Tregs in peripheral blood, and IFN-γ, IL-4, Forkhead box transcription factor 3 (FoxP3) in lung tissue were observed by enzyme-linked immunosorbent assay, flow cytometry, polymerase chain reaction, and western blot .RESULTS: Compared with the NC group, paw swelling, AI, IFN- γ, and Th1 / Th2 were increased (P <0.05 or P <0.01) .Pulmonary function parameters, Treg, IL-4, FoxP3 (and mRNA) were higher, and paw swelling, AI, and IFN-γ (and mRNA) were lower in the XFC group than those in the MC group. The XFC group was also much better than the TPT group in improving pulmonary function, FoxP3 mRNA, IFN- γ, IL-4, Th1 / Th2, and IL-10 (P <0.05 or P <0.01) .CONCLUSION: Xinfeng capsule can improve pulmonary function by regulating the levels of Tregs, inhibiting the activation of Th1 to Th2 cells, inducing drift, maintaining cell immune suppression, the imbalance of Th1 / Th2, and reducing inflammatory mediators.