A novel gut inflammatory rat model by laparotomic injection of peptidoglycan from Staphylococcus aureus

Inflammatory bowel disease includes ulcerative colitis and Crohn's disease, and is globally increasing. An appropriate model system is required to dissect the disease pathogenesis and drugs screening for adequate treatment. In the present study, we established a novel model of gut inflammation by injecting peptidoglycan from Staphylococcus aureus using laparotomic procedure. For this, three different doses of peptidoglycan, i.e., 2.5, 5 and 10 mg/kg body weight were used. The treatment effect was evaluated by studying the macrophage phagocytic function, spleen lymphocytes' proliferation and qRT-PCR for the assessment of peritoneal cells' gene expression. In addition, histological analysis of gut sections, gastric acidity, immunoglobulins and cytokines were assessed. There was significant increase in phagocytic activity in 10 mg/kg body weight PGN group. A dose dependent increase in spleen lymphocytes' proliferation and a significant increase in total acid secretion in 5 and 10 mg/kg body weight PGN treated rats were observed. In addition, a significant increment in TLR-2 and CD-14 mRNA expression in peritoneal cells, TNF-α, IL-6 and IFN-γ level and maximum distortion of gut architecture was observed in 10 mg/kg body weight PGN group. Hence, peptidoglycan from S. aureus can be used for establishing the screening model to study the action and mechanism of anti-inflammatory food products and drugs.