Toll-like receptor-4 dependent small intestinal immune responses following murine Arcobacter butzleri infection

Abstract

Sporadic cases of gastroenteritis have been attributed to Arcobacter butzleri infection, but information about the underlying immunopathological mechanisms is scarce. We have recently shown that experimental A. butzleri infection induces intestinal, extraintestinal and systemic immune responses in gnotobiotic IL-10–/– mice. The aim of the present study was to investigate the immunopathological role of Toll-like Receptor-4, the receptor for lipopolysaccharide and lipooligosaccharide of Gram-negative bacteria, during murine A. butzleri infection. To address this, gnotobiotic IL-10–/– mice lacking TLR-4 were generated by broad-spectrum antibiotic treatment and perorally infected with two different A. butzleri strains isolated from a patient (CCUG 30485) or fresh chicken meat (C1), respectively. Bacteria of either strain stably colonized the ilea of mice irrespective of their genotype at days 6 and 16 postinfection. As compared to IL-10–/– control animals, TLR-4–/– IL-10–/– mice were protected from A. butzleri-induced ileal apoptosis, from ileal influx of adaptive immune cells including T lymphocytes, regulatory T-cells and B lymphocytes, and from increased ileal IFN-γ secretion. Given that TLR-4-signaling is essential for A. butzleri-induced intestinal inflammation, we conclude that bacterial lipooligosaccharide or lipopolysaccharide compounds aggravate intestinal inflammation and may thus represent major virulence factors of Arcobacter. Future studies need to further unravel the molecular mechanisms of TLR-4-mediated A. butzleri-host interactions.

The Immunopathogenic Potential of Arcobacter butzleri – Lessons from a Meta-Analysis of Murine Infection Studies

“…Notably, before our previous reports on A . butzleri infected gnotobiotic IL-10 -/- mice [ 13 – 16 ], only one single in vivo study in mice had been published showing that the adherent properties of initially low-adherent A . butzleri strains were enhanced upon serial intraperitoneal passages [ 33 ].…”

“…butzleri infection studies, however, clearly revealed that despite absence of overt gross disease, distinct infection-induced intestinal, extra-intestinal and even systemic sequelae could be observed in an A . butzleri strain dependent manner [ 13 – 16 ]. These results indicate that gnotobiotic IL-10 -/- mice might serve as infection model to investigate Arcobacter -host interactions to some extent.…”

“…Recent investigations revealed that A . butzleri induced small and large intestinal as well as extra-intestinal and systemic immune responses were TLR-4 dependent [ 15 , 16 ]. The fact that Arcobacter strains express variable LPS or LOS structures might further determine whether a specific strain rather acts as a pathogen or a commensal in a susceptible or resistant host.…”

“…butzleri induced intestinal and systemic immune responses [ 13 , 14 ]. These immune reponses were highly dependent on Toll-like-receptor (TLR) -4 constituting the main receptor for lipooligosaccharide (LOS) and lipopolysaccharide (LPS) from gram-negative bacteria [ 15 , 16 ]. In the present study we assessed the immunopathological potential of A .…”

Immune Responses to Broad-Spectrum Antibiotic Treatment and Fecal Microbiota Transplantation in Mice

“…In situ immunohistochemical analysis of ileal and colonic paraffin sections was performed as previously described ( 25 – 28 ). Primary antibodies against cleaved caspase-3 (Asp175, Cell Signaling, Beverly, MA, USA, 1:200), Ki67 (TEC3, Dako, Glostrup, Denmark, 1:100), CD3 (#N1580, Dako, 1:10), Foxp3 (FJK-16s, eBioscience, San Diego, CA, USA, 1:100), B220 (eBioscience, 1:200), and F4/80 (# 14-4801, clone BM8, eBioscience, 1:50) were used.…”