Abbreviations: AMP, antimicrobial peptide; CB1/2, cannabinoid receptor type 1 or 2; FGD, functional gastrointestinal disorder; FISH, fluorescent in situ hybridization; GCM, gut commensal microbiota; GI, gastrointestinal; IBS, irritable bowel syndrome; iNOS, inducible nitric oxide synthase; MOR, mu-opioid receptor; NGF, nerve growth factor; PPR, pattern recognition receptor; Reg3g, regenerating islet-derived protein 3 gamma; RELMb, resistin-like molecule-b; RT-qPCR, reverse transcription quantitative polymerase chain reaction; SFB, segmented filamentous bacteria; sIgA, secretory IgA; TLR, toll-like receptor; TPH 1/2, tryptophan hydroxylase isoforms 1 or 2; TRPV1/3, transient receptor potential vanilloid types 1 or 3Alterations in the composition of the commensal microbiota (dysbiosis) seem to be a pathogenic component of functional gastrointestinal disorders, mainly irritable bowel syndrome (IBS), and might participate in the secretomotor and sensory alterations observed in these patients.We determined if a state antibiotics-induced intestinal dysbiosis is able to modify colonic pain-related and motor responses and characterized the neuro-immune mechanisms implicated in mice. A 2-week antibiotics treatment induced a colonic dysbiosis (increments in Bacteroides spp, Clostridium coccoides and Lactobacillus spp and reduction in Bifidobacterium spp). Bacterial adherence was not affected. Dysbiosis was associated with increased levels of secretory-IgA, up-regulation of the antimicrobial lectin RegIIIg, and toll-like receptors (TLR) 4 and 7 and down-regulation of the antimicrobial-peptide Resistin-Like Molecule-b and TLR5. Dysbiotic mice showed less goblet cells, without changes in the thickness of the mucus layer. Neither macroscopical nor microscopical signs of inflammation were observed. In dysbiotic mice, expression of the cannabinoid receptor 2 was up-regulated, while the cannabinoid 1 and the mu-opioid receptors were down-regulated. In antibiotic-treated mice, visceral painrelated responses elicited by intraperitoneal acetic acid or intracolonic capsaicin were significantly attenuated. Colonic contractility was enhanced during dysbiosis. Intestinal dysbiosis induce changes in the innate intestinal immune system and modulate the expression of pain-related sensory systems, an effect associated with a reduction in visceral painrelated responses. Commensal microbiota modulates gut neuro-immune sensory systems, leading to functional changes, at least as it relates to viscerosensitivity. Similar mechanisms might explain the beneficial effects of antibiotics or certain probiotics in the treatment of IBS.
Haemophilus parasuis is the aetiological agent of Glä sser's disease in swine. In addition, this bacterium causes other clinical outcomes and can also be isolated from the upper respiratory tract of healthy pigs. Isolates of H. parasuis differ in phenotypic features (e.g. protein profiles, colony morphology or capsule production) and pathogenic capacity. Differences among strains have also been demonstrated at the genetic level. Several typing methods have been used to classify H. parasuis field strains, but they had resolution or implementation problems. To overcome these limitations, a multilocus sequence typing (MLST) system, using partial sequences of the house-keeping genes mdh, 6pgd, atpD, g3pd, frdB, infB and rpoB, was developed. Eleven reference strains and 120 field strains were included in this study. The number of alleles per locus ranged from 14 to 41, 6pgd being the locus with the highest diversity. The high genetic heterogeneity of this bacterium was confirmed with MLST, since the strains were divided into 109 sequence types, and only 13 small clonal complexes were detected by the Burst algorithm. Further analysis by unweighted-pair group method with arithmetic mean (UPGMA) identified six clusters. When the clinical background of the isolates was examined, one cluster was statistically associated with nasal isolation (putative non-virulent), while another cluster showed a significant association with isolation from clinical lesions (putative virulent). The remaining clusters did not show a statistical association with the clinical background of the isolates. Finally, although recombination among H. parasuis strains was detected, two divergent branches were found when a neighbour-joining tree was constructed with the concatenated sequences. Interestingly, one branch included almost all isolates of the putative virulent UPGMA cluster. INTRODUCTIONHaemophilus parasuis is a member of the family Pasteurellaceae and the causative agent of Glässer's disease in pigs, which is pathologically characterized by fibrinous to fibrinopurulent polyserositis and polyarthritis (RappGabrielson et al., 2006). In addition to Glässer's disease, H. parasuis produces other clinical outcomes, such as pneumonia, and colonizes the upper respiratory tract of healthy animals (Rapp-Gabrielson et al., 2006). Although it is commonly accepted that one strain is responsible for each clinical outbreak, diagnosis of H. parasuis infection is complicated by the fact that it is usual to detect several strains in a farm and even within a single animal. Therefore, it is essential to determine the causative strain by its isolation from organs with the characteristic lesions of the disease.Differences among strains in phenotypic and genotypic characteristics have been reported, although no clear association with virulence could be determined (Oliveira & Pijoan, 2004;Rapp-Gabrielson et al., 2006). However, several studies have confirmed that different strains of H. parasuis have different pathogenic capacity (Kielstein & Rapp-Gabrielson, 199...
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