LC40 can reduce the activity of lupus and splenomegaly in SLE mice, improving the integrity of the intestinal barrier, reducing the plasma level of lipopolysaccharide (LPS), and subsequently decreasing the immune activation, which was characterized by reduced T and B cells in mesenteric lymph nodes (MLNs) and declined plasma pro-inflammatory factors, containing TNF-α, IFN-γ, IL-17a, and IL-21. This evidence concerns the gene IL21 and systemic lupus erythematosus.