IL21 and systemic lupus erythematosus: SLE patients treated with glucocorticoid had a similar gut microbial community with healthy controls. Bacteroides, Succinivibrio, Bilophila, and Parabateroides were positively correlated with IL-17, TWEAK, IL-2R, IL-21, IL-35, IL-10, and IFN-γ.Dialister and Gemmiger were negatively correlated with immune factors IL-17, IL-2R, and IL-35.