Campylobacter jejuni Induces Colitis Through Activation of Mammalian Target of Rapamycin Signaling

Abstract

BACKGROUND & AIMS Campylobacter jejuni is the worldwide leading cause of bacterial-induced enteritis. The molecular and cellular events that lead to campylobacteriosis are poorly understood. We identify mammalian target of rapamycin (mTOR) as a signaling pathway that leads to C jejuni-induced intestinal inflammation. METHODS Germ-free (control) or conventionally-derived interleukin (Il)10−/− mice that express enhanced green fluorescent protein under the control of NF-κB (Il10 −/−; NF-κBEGFP mice) were infected with C jejuni (109 CFU/mouse) for 12 days; their responses were determined using histologic, semi-quantitative reverse transcription PCR, fluorescence in situ hybridization, transmission electron microscopy, and tissue culture analyses. mTOR signaling was blocked by daily intraperitoneal injections of the pharmacologic inhibitor rapamycin (1.5 mg/kg). CD4+ T cells were depleted by intraperitoneal injections of antibodies against CD4 (0.5 mg/mouse, every 3 days). Bacterial survival in splenocytes was measured using a gentamycin killing assay. RESULTS C jejuni induced intestinal inflammation, which correlated with activation of mTOR signaling and neutrophil infiltration. The inflamed intestines of these mice had increased levels of Il-1β, Cxcl2, Il-17a, and EGFP; C jejuni localized to colons and extra-intestinal tissues of infected Il10−/−; NF-κBEGFP mice, compared with controls. Rapamycin, administered before or after introduction of C jejuni, blocked C jejuni-induced intestinal inflammation and bacterial accumulation. LC3II processing and killing of C jejuni were increased in splenocytes incubated with rapamycin, compared with controls. CONCLUSIONS mTOR signaling mediates C jejuni-induced colitis in Il10−/− mice, independently of T-cell activation. Factors involved in mTOR signaling might be therapeutic targets for campylobacteriosis.

The Human Milk Oligosaccharide 2′-Fucosyllactose Quenches Campylobacter jejuni–Induced Inflammation in Human Epithelial Cells HEp-2 and HT-29 and in Mouse Intestinal Mucosa

“…Inflammatory cytokine and chemokine mRNAs were quantified by RT-PCR. Primer sequences (30)(31)(32) are shown in Supplemental Table 1.…”

The Microbiota Protects against Ischemia/Reperfusion-Induced Intestinal Injury through Nucleotide-Binding Oligomerization Domain-Containing Protein 2 (NOD2) Signaling

“…For quantitative real-time PCR, relative fold changes of Il6, Il1, and Tnfa were determined using the DDC T calculation method, as previously described. 23 Values were normalized to the internal controls, b-actin and Gapdh. Primers were as follows: 23,24 Cell Culture and Immunocytochemistry…”

The Chronic Gastrointestinal Consequences Associated With Campylobacter

“…Recent evidence that the organism takes advantage of the host's innate immunity to cause pathology and invasion was demonstrated by attenuation of C. jejuni invasion and colitis in a murine model by administration of rapamycin (mTOR inhibitor) prior to and after clinical disease caused by a challenge strain [27]. Expression of the proinflammatory mediator NF-kβ in the lamina propria, neutrophil migration into the epithelium, and invasiveness were all decreased.…”