Diet also emerges as a significant factor, with studies indicating that the gut epithelium and the gut microbiota play critical roles in maintaining barrier function and inflammation in the gut and colon.[40–42]Angelica polysaccharide has been found to modulate the intestinal microbiota and alter the expression of genes such as Cldn5, Slit3, and Rgs18, ultimately improving RA.[43]. Here, CLDN5 is linked to rheumatoid arthritis.