The results of the expression levels of tight junction proteins in IPEC-J2 cells showed that, compared with the control group, the expression of claudin-1 was significantly elevated by L. plantarum Lac16 treatment (p < 0.05), whereas it was significantly suppressed by C. perfringens infection (p < 0.01; Figure 4D and Figure S3). This evidence concerns the gene CLDN1 and infection due to clostridium perfringens.