NF-kappa B-iNOS-COX2-TNF alpha inflammatory signaling pathway plays an important role in methotrexate induced small intestinal injury in rats

Although methotrexate is widely used in clinics as an anticancer agent, it's utility is limited by its gastrointestinal toxicity, the mechanism of which is unclear. The role of NF kappa B inflammatory pathway in MTX induced mucositis was investigated in the present study. GI injury was induced in adult Wistar rats by the administration of 3 consecutive i.p . injections of MTX. On the fourth day, the rats were sacrificed and the small intestine was removed; A piece was used for light microscopy, immunohistochemistry, immunofluorescence studies . The mucosa was collected and used for the analysis of protein and mRNA expressions of NF kappa B and its target genes by the western blot, RT-PCR respectively. MTX treatment resulted in NF kappa B activation and nuclear translocation as evidenced by immunofluorescence, immunohistochemistry , and western blot. NF kappa B mRNA was also increased. There was increased protein and mRNA expressions of NF kappa B target genes, TNF-alpha, iNOS, COX-2, PLA2, HO-1, HSP70, MMPs 2 and 9 . Aminoguanidine pretreatment (30mg/ 50mg /kg body wt.) attenuated MTX induced activation of NF kappa B and its proinflammatory target genes and improved MIX induced morphological changes. Aminoguanidine has protective effects against MIX induced gastrointestinal mucositis in rats.