Arcobacter butzleri Induce Colonic, Extra-Intestinal and Systemic Inflammatory Responses in Gnotobiotic IL-10 Deficient Mice in a Strain-Dependent Manner

Abstract

BackgroundThe immunopathological impact of human Arcobacter (A.) infections is under current debate. Episodes of gastroenteritis with abdominal pain and acute or prolonged watery diarrhea were reported for A. butzleri infected patients. Whereas adhesive, invasive and cytotoxic capacities have been described for A. butzleri in vitro, only limited information is available about the immunopathogenic potential and mechanisms of infection in vivo.Methodology/Principal FindingsGnotobiotic IL-10-/- mice were generated by broad-spectrum antibiotic treatment and perorally infected with the A. butzleri strains CCUG 30485 and C1 shown to be invasive in cell culture assays. Bacterial colonization capacities, clinical conditions, intestinal, extra-intestinal and systemic immune responses were monitored at day six and 16 postinfection (p.i.). Despite stable intestinal A. butzleri colonization at high loads, gnotobiotic IL-10-/- mice were virtually unaffected and did not display any overt symptoms at either time point. Notably, A. butzleri infection induced apoptosis of colonic epithelial cells which was paralleled by increased abundance of proliferating cells. Furthermore A. butzleri infection caused a significant increase of distinct immune cell populations such as T and B cells, regulatory T cells, macrophages and monocytes in the colon which was accompanied by elevated colonic TNF, IFN-γ, nitric oxide (NO), IL-6, IL-12p70 and MCP-1 concentrations. Strikingly, A. butzleri induced extra-intestinal and systemic immune responses as indicated by higher NO concentrations in kidney and increased TNF, IFN-γ, IL-12p70 and IL-6 levels in serum samples of infected as compared to naive mice. Overall, inflammatory responses could be observed earlier in the course of infection by the CCUG 30485 as compared to the C1 strain.Conclusion/SignificancePeroral A. butzleri infection induced not only intestinal but also extra-intestinal and systemic immune responses in gnotobiotic IL-10-/- mice in a strain-dependent manner. These findings point towards an immunopathogenic potential of A. butzleri in vertebrate hosts.

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

“…The immunopathological impact of A. butzleri infection in vivo is under current debate. Data regarding the molecular mechanisms underlying potential host interactions with this emerging pathogen are lacking due to the scarcity of appropriate in vivo models [ 20 ]. In the present study, we have applied our gnotobiotic (i.e., secondary abiotic) IL-10 –/– mouse infection model in order to unravel the role of TLR-4, the major innate immune receptor for sensing of LPS and LOS derived from the cell wall of Gram-negative bacteria, in murine Arcobacter infection.…”

“…The A. butzleri reference strain CCUG 30485 was initially isolated from a fecal sample derived from a diarrheal patient [ 23 ], whereas the C1 strain was isolated from fresh chicken meat [ 10 ]. Both A. butzleri strains were grown on Karmali-Agar (Oxoid, Wesel, Germany) for 2 days at 37 °C under microaerobic conditions using CampyGen gas packs (Oxoid) as described earlier [ 20 , 21 , 26 ].…”

“…We have recently shown that, upon peroral A. butzleri infection, gnotobiotic IL-10 –/– mice with a depleted commensal microbiota following broad-spectrum antibiotic treatment [ 19 ] could be stably infected by the bacterium and displayed significant small and large intestinal pro-inflammatory immune responses [ 20 , 21 ]. Remarkably, infection-induced sequelae were not restricted to the intestinal tract, given that even systemic inflammatory responses could be observed in infected mice.…”

Toll-like receptor-4 is essential for Arcobacter butzleri-induced colonic and systemic immune responses in gnotobiotic IL-10−/− mice

“…The A. butzleri reference strain CCUG 30485 was initially isolated from a fecal sample derived from a diarrheal patient [ 31 ], whereas the C1 strain was isolated from fresh chicken meat [ 11 ]. Both A. butzleri strains were grown on Karmali-agar (Oxoid, Wesel, Germany) for 2 days at 37 °C under microaerobic conditions using CampyGen gas packs (Oxoid) as described earlier [ 23 , 27 , 28 ].…”

“…Given that C. jejuni and A. butzleri are taxonomically related, we very recently applied the gnotobiotic IL-10 –/– mouse model to determine the pathogenic potential of A. butzleri and to investigate bacterial–host interactions in vivo . The results indicate that, upon peroral A. butzleri infection, mice could be stably colonized by the respective strains and displayed significant small and large intestinal as well as extraintestinal and systemic inflammatory responses [ 27 , 28 ].…”