1045 Campylobacter Jejuni Induces Rapid and Severe Colitis in Gnotobiotic IL-10-/- Mice Through a MyD88 Independent Pathway

Abstract

Introduction: The Gram-negative bacterium Campylobacter jejuni (C. jejuni) is the leading cause of food-borne diarrheal illnesses worldwide. Limited information is available on the molecular mechanisms associated with its pathogenesis. Aim: To characterize the host responses associated with C. jejuni-induced intestinal inflammation and to define themolecular mechanisms associated with the pathogenesis. Methods: Germ-free IL-10wt/wt;NF-κBEGFP and IL-10-/-;NF-κBEGFP mice were mono-associated with different amount of C. jejuni (strain 81-176; 102, 104, 106, 109cfu/mouse). IL-10-/and IL-10-/-;Myd88-/were associated with C. jejuni under specific pathogen-free (SPF) conditions (108cfu/mouse). Bacterial colonization and extraintestinal manifestations were confirmed by culturing stool, mesenteric lymph nodes (MLN), spleen and liver collected from each group and by real-time PCR (RT-PCR). Macroscopic and confocal microscopic EGFP imaging, RT-PCR analysis and histological analysis were utilized to characterize the bacteria-induced host responses. Colonoscopy was performed to document inflammation using a mini STORZ endoscope. Results: C. jejuni mono-associated IL-10-/mice developed mild (102), moderate (104) and severe (109) inflammation by day 14 as assayed by colonoscopy. Five days after association all mice had clinical signs of inflammation as evidenced by bloody diarrhea. Macroscopic analysis showed elevated EGFP expression throughout the colon of C. jejuni (109) associated IL-10-/-;NF-κBEGFP mice. All mice were colonized equally with C. jejuni as confirmed by RT-PCR and stool sample cultures. Histological analysis showed severe crypt hyperplasia, goblet cell depletion, ulcers and immune cell infiltration. TNF and IL-12p40 mRNA were significantly induced in the colon of these mice compared to WT mice. C. jejuni-induced IL-12p40, IL-23p19 and TNF gene expression was reduced in BMCD generated from IL-10-/-;Myd88-/compared to IL10-/mice. Interestingly, the onset and extent of C. jejuni-induced colitis is similar between IL-10-/-;Myd88-/and IL-10-/mice with comparable induction of TNF, Nod2, and IL-23p19 gene expression. Conclusion: Our findings indicate that C. jejuni induces rapid and severe intestinal inflammation in a susceptible host, which correlates with enhanced NF-κB activity. C. jejuni-induced colitis in IL-10-/mice appears to be mediated by a Myd88-independent pathway. These findings raise the possibility that Nod proteins are involved in C. jejuniinduced colitis.