Effect of Infliximab on Radiation-Induced Submandibular Gland Dysfunction in Rats

Inflammatory response is one of the essential parts of various pathogenic mechanisms of radiation-induced salivary dysfunction. The effect of decreasing the levels of inflammatory cytokines on alleviating submandibular gland injuries after irradiation is unclear. This study aimed to explore the effect of the antibody against tumor necrosis factor-alpha, infliximab, on radiation-induced submandibular gland dysfunction in rats. Male Wistar rats received a single 20 Gy dose to the right submandibular gland region or sham irradiated. Meanwhile, the irradiated group was divided into infliximab treatment groups or untreated groups. Animals were euthanized at 1, 6, and 12 weeks postirradiation, and the irradiated submandibular gland was dissected for subsequent detection. Submandibular gland exposure caused obvious pathological changes. The increased levels of inflammatory cytokines, including tumor necrosis factor-alpha, interleukin-1β, and interleukin-6, represent an aggravated inflammatory response. The results of the western blot, reverse transcription-quantitative polymerase chain reaction, and immunofluorescence staining showed upregulated levels of claudin-1, claudin-3, and aquaporin 5 and downregulated levels of claudin-4. Moreover, nuclear factor kappa-B phosphorylation levels were also up-regulated. In subsequent experiments, we found that infliximab alleviated inflammatory response, up-regulated tumor necrosis factor-alpha, interleukin-1β, and interleukin-6 levels, and improved claudin-1, claudin-3, claudin-4, and aquaporin 5 expression. Our results indicate that infliximab might improve the para-cellular pathway and trans-cellular pathway destruction by reducing the inflammatory.