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Authors: Greta Gölz, Gül Karadas, André Fischer, Ulf B. Göbel, Thomas Alter, Stefan Bereswill and Markus M. Heimesaat

Arcobacter butzleri causes sporadic cases of gastroenteritis, but the underlying immunopathological mechanisms of infection are unknown. We have recently demonstrated that A. butzleri-infected gnotobiotic IL-10−/− mice were clinically unaffected but exhibited intestinal and systemic inflammatory immune responses. For the first time, we here investigated the role of Toll-like receptor (TLR)-4, the main receptor for lipopolysaccharide and lipooligosaccharide of Gram-negative bacteria, in murine arcobacteriosis. Gnotobiotic TLR-4/IL-10-double deficient (TLR-4−/− IL-10−/−) and IL-10−/− control mice generated by broad-spectrum antibiotics were perorally infected with A. butzleri. Until day 16 postinfection, mice of either genotype were stably colonized with the pathogen, but fecal bacterial loads were approximately 0.5–2.0 log lower in TLR-4−/− IL-10−/− as compared to IL-10−/− mice. A. butzleri-infected TLR-4−/− IL-10−/− mice displayed less pronounced colonic apoptosis accompanied by lower numbers of macrophages and monocytes, T lymphocytes, regulatory T-cells, and B lymphocytes within the colonic mucosa and lamina propria as compared to IL-10−/− mice. Furthermore, colonic concentrations of nitric oxide, TNF, IL-6, MCP-1, and, remarkably, IFN and IL-12p70 serum levels were lower in A. butzleri-infected TLR-4−/− IL-10−/− versus IL-10−/− mice. In conclusion, TLR-4 is involved in mediating murine A. butzleri infection. Further studies are needed to investigate the molecular mechanisms underlying Arcobacter—host interactions in more detail.

Open access
Authors: Markus M. Heimesaat, Gül Karadas, André Fischer, Ulf B. Göbel, Thomas Alter, Stefan Bereswill and Greta Gölz

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 broadspectrum 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 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.

Open access

We have previously shown that Arcobacter butzleri induces intestinal, extra-intestinal, and systemic immune responses in perorally infected gnotobiotic IL-10−/− mice in a strain-dependent fashion. Here, we present a comprehensive survey of small and large intestinal expression profiles of inflammatory and regulatory mediators as well as of the matrix-degrading gelatinases MMP-2 and MMP-9 following murine A. butzleri infection. Gnotobiotic IL-10−/− mice were infected with A. butzleri strains CCUG 30485 or C1 of human and chicken origin, respectively. At day 6 following A. butzleri infection, mucin-2 mRNA, an integral part of the intestinal mucus layer, was downregulated in the colon, whereas TNF and IL-23p19 mRNA were upregulated in the ileum. Furthermore, IFN-γ, IL-17A, IL-1β, and IL-22 mRNA were upregulated in both colonic and ileal ex vivo biopsies at day 6 post strain CCUG 30485 infection. These changes were accompanied by downregulated colonic MMP-9 levels, whereas both MMP-2 and MMP-9 mRNA were upregulated in the ileum. In conclusion, these data indicate that A. butzleri infection induces changes in the expression of genes involved in pro-inflammatory and regulatory immune responses as well as in tissue degradation.

Open access

We have previously shown that Arcobacter butzleri infection induces Toll-like receptor (TLR) -4 dependent immune responses in perorally infected gnotobiotic IL-10−/− mice. Here, we analyzed TLR-4-dependent expression of genes encoding inflammatory mediators and matrix-degrading gelatinases MMP-2 and -9 in the small and large intestines of gnotobiotic TLR-4-deficient IL-10−/− mice that were perorally infected with A. butzleri strains CCUG 30485 or C1, of human and chicken origin, respectively. At day 6 following A. butzleri infection, colonic mucin-2 mRNA, as integral part of the intestinal mucus layer, was downregulated in the colon, but not ileum, of IL-10−/− but not TLR-4−/− IL-10−/− mice. CCUG 30485 strain-infected TLR-4-deficient IL-10−/− mice displayed less distinctly upregulated IFN-γ, IL-17A, and IL-1β mRNA levels in ileum and colon, which was also true for colonic IL-22. These changes were accompanied by upregulated colonic MMP-2 and ileal MMP-9 mRNA exclusively in IL-10−/− mice. In conclusion, TLR-4 is essentially involved in A. butzleri mediated modulation of gene expression in the intestines of gnotobiotic IL-10−/− mice.

Open access
Authors: Markus M. Heimesaat, Marie E. Alutis, Ursula Grundmann, André Fischer, Ulf B. Göbel and Stefan Bereswill

We have recently shown that, within 1 week following peroral Campylobacter jejuni infection, conventional infant mice develop self-limiting enteritis. We here investigated the role of IL-23, IL-22, and IL-18 during C. jejuni strain 81-176 infection of infant mice. The pathogen efficiently colonized the intestines of IL-18−/− mice only, but did not translocate to extra-intestinal compartments. At day 13 postinfection (p.i.), IL-22−/− mice displayed lower colonic epithelial apoptotic cell numbers as compared to wildtype mice, whereas, conversely, colonic proliferating cells increased in infected IL-22−/− and IL-18−/− mice. At day 6 p.i., increases in neutrophils, T and B lymphocytes were less pronounced in gene-deficient mice, whereas regulatory T cell numbers were lower in IL-23p19−/− and IL-22−/− as compared to wildtype mice, which was accompanied by increased colonic IL-10 levels in the latter. Until then, colonic pro-inflammatory cytokines including TNF, IFN-γ, IL-6, and MCP-1 increased in IL-23p19−/− mice, whereas IL-18−/− mice exhibited decreased cytokine levels and lower colonic numbers of T and B cell as well as of neutrophils, macrophages, and monocytes as compared to wildtype controls. In conclusion, IL-23, IL-22, and IL-18 are differentially involved in mediating C. jejuni-induced immunopathology of conventional infant mice.

Open access
Authors: Markus M. Heimesaat, Ursula Grundmann, Marie E. Alutis, André Fischer, Ulf B. Göbel and Stefan Bereswill

Within 1 week following peroral Campylobacter jejuni infection, infant mice develop acute enteritis resolving thereafter. We here assessed colonic expression profiles of mediators belonging to the IL-23/IL-22/IL-18 axis and of matrix-degrading gelatinases MMP-2 and MMP-9 at day 6 post C. jejuni strain 81-176 infection. Whereas the pathogen readily colonized the intestines of infant IL-18−/− mice only, colonic mucin-2 mRNA, a pivotal mucus constituent, was downregulated in IL-22−/− mice and accompanied by increased expression of pro-inflammatory cytokines including IFN-γ, TNF, IL-17A, and IL-1β. Furthermore, in both naive and infected IL-22−/− mice, colonic expression of IL-23p19 and IL-18 was lower as compared to wildtype mice, whereas, conversely, colonic IL-22 mRNA levels were lower in IL-18−/− and colonic IL-18 expression lower in IL-23p19−/− as compared to wildtype mice. Moreover, colonic expression of MMP-2 and MMP-9 and their endogenous inhibitor TIMP-1 were lower in IL-22−/− as compared to wildtype mice at day 6 postinfection. In conclusion, mediators belonging of the IL-23/IL-22/IL-18 axis as well as the gelatinases MMP-2 and MMP-9 are involved in mediating campylobacteriosis of infant mice in a differentially regulated fashion.

Open access

Host immune responses are pivotal for combating enteropathogenic infections. We here assessed the impact of the innate receptor nucleotide oligomerization domain protein 2 (NOD2) in murine Campylobacter jejuni-infection. Conventionally colonized IL-10−/− mice lacking NOD2 and IL-10−/− controls were perorally challenged with C. jejuni strain 81-176 and displayed comparable pathogenic colonization of intestines until day 14 postinfection (p.i.). Whereas overall intestinal microbiota compositions were comparable in naive mice, NOD2−/− IL-10−/− mice exhibited less fecal bifidobacteria and lactobacilli than IL-10−/− counterparts after infection. Interestingly, NOD2−/− IL-10−/− mice were clinically more compromised during the early phase of infection, whereas, conversely, IL-10−/− animals exhibited more frequently bloody feces lateron. While colonic apoptotic cell and T lymphocyte numbers were comparable in either C. jejuni-infected mice, B lymphocytes were lower in the colon of infected NOD2−/− IL-10−/− mice versus controls. At day 14 p.i., colonic TNF and IL-23p19 mRNA levels were upregulated in NOD2−/− IL-10−/− mice only. Translocation rates of intestinal commensals to mesenteric lymphnodes and extra-intestinal compartments including liver and kidney were comparable, whereas viable bacteria were more frequently detected in spleens derived from IL-10−/− as compared to NOD2−/− IL-10−/− mice. In conclusion, NOD2 is involved during C. jejuni infection in conventionally colonized IL-10−/− mice in a time-dependent manner.

Open access

increased numbers of T and B lymphocytes in the colonic mucosa and lamina propria [ 13, 24 ], the T and B cell lowering effects upon Aviguard® application observed here might point towards a potential immune-modulatory effect that might dampen pro-inflammatory

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activating the immune system of the hosts [ 25 ]. Just a single recent review lists many major functions for AMPs, such as direct anti-microbial effects, clearance of endotoxins, chemotaxis, modification of anti- and pro-inflammatory immune responses, wound

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