CLDN1 and metabolic disease: In summary, PPSP could alleviate metabolic diseases by improving intestinal barrier function with upregulating GLUT4, GPR43, NLCR3, p38 MAPK, TRAF6-mediated signaling pathways and the expressions of claudin 1, GLP1, IL-10, occludin 1, and ZO-1 (Figure 1).