CLDN1 and colitis: Thus, PST treatment in male mice promoted the early onset of colitis and increased the colon mRNA expression of proinflammatory cytokines IL-8 and IL-18 by reducing the alternative activated macrophage activity and expression levels of TJ proteins CLD1, zonula occludens-1, occludin, and E-cadherin-1 during DSS-mediated colitis [27].