Meanwhile, the expression of the tight junction protein ZO-1 and claudin-1 and the cell adhesion protein E-cadherin in the ileum and colon were reduced in NEC mice through immunofluorescence and western blotting, and C. tyrobutyricum treatment remarkably improved the expression of ZO-1 and E-cadherin (Fig. 4F and G; Fig.S3A). Here, CLDN1 is linked to necrotizing enterocolitis.