Induction of immunomodulatory miR-146a and miR-155 in small intestinal epithelium of Vibrio cholerae infected patients at acute stage of cholera

PLoS One. 2017 Mar 20;12(3):e0173817. doi: 10.1371/journal.pone.0173817. eCollection 2017.

Abstract

The potential immunomodulatory role of microRNAs in small intestine of patients with acute watery diarrhea caused by Vibrio cholerae O1 or enterotoxigenic Escherichia coli (ETEC) infection was investigated. Duodenal biopsies were obtained from study-participants at the acute (day 2) and convalescent (day 21) stages of disease, and from healthy individuals. Levels of miR-146a, miR-155 and miR-375 and target gene (IRAK1, TRAF6, CARD10) and 11 cytokine mRNAs were determined by qRT-PCR. The cellular source of microRNAs in biopsies was analyzed by in situ hybridization. The ability of V. cholerae bacteria and their secreted products to cause changes in microRNA- and mRNA levels in polarized tight monolayers of intestinal epithelial cells was investigated. miR-146a and miR-155 were expressed at significantly elevated levels at acute stage of V. cholerae infection and declined to normal at convalescent stage (P<0.009 versus controls; P = 0.03 versus convalescent stage, pairwise). Both microRNAs were mainly expressed in the epithelium. Only marginal down-regulation of target genes IRAK1 and CARD10 was seen and a weak cytokine-profile was identified in the acute infected mucosa. No elevation of microRNA levels was seen in ETEC infection. Challenge of tight monolayers with the wild type V. cholerae O1 strain C6706 and clinical isolates from two study-participants, caused significant increase in miR-155 and miR-146a by the strain C6706 (P<0.01). One clinical isolate caused reduction in IRAK1 levels (P<0.05) and none of the strains induced inflammatory cytokines. In contrast, secreted factors from these strains caused markedly increased levels of IL-8, IL-1β, and CARD10 (P<0.001), without inducing microRNA expression. Thus, miR-146a and miR-155 are expressed in the duodenal epithelium at the acute stage of cholera. The inducer is probably the V. cholerae bacterium. By inducing microRNAs the bacterium can limit the innate immune response of the host, including inflammation evoked by its own secreted factors, thereby decreasing the risk of being eliminated.

MeSH terms

  • Acute Disease
  • Adult
  • CARD Signaling Adaptor Proteins / genetics
  • Cholera / genetics
  • Cholera / immunology*
  • Cholera / pathology
  • Gene Expression Regulation / immunology
  • Humans
  • Immunity, Innate
  • Immunomodulation*
  • Interleukin-1 Receptor-Associated Kinases / genetics
  • Intestinal Mucosa / immunology*
  • Intestinal Mucosa / metabolism
  • Intestine, Small / immunology*
  • Intestine, Small / metabolism
  • Male
  • MicroRNAs / genetics*
  • Middle Aged
  • TNF Receptor-Associated Factor 6 / genetics
  • Vibrio cholerae / physiology*
  • Young Adult

Substances

  • CARD Signaling Adaptor Proteins
  • CARD10 protein, human
  • MIRN146 microRNA, human
  • MIRN155 microRNA, human
  • MicroRNAs
  • TNF Receptor-Associated Factor 6
  • IRAK1 protein, human
  • Interleukin-1 Receptor-Associated Kinases

Grants and funding

This research was supported by the icddr,b and by grants from the Swedish International Development Cooperation Agency (SIDA) grant INT-ICDDR,B-HN-01-AV to F.Q., the Swedish Research Council-Natural and Engineering Sciences grant no. 2013-4522 to M-L.H. and grant no. 2014-4401 to S.N.W., the TORNADO-project within the 7th framework program theme, grant agreement no. 222720-2 to M-L.H., the Fund for Biotechnology-oriented Basic Science at Umeå University to M-L.H., the Kempe Foundations grant no. SMK-1454 to S.N.W., the Science Foundation Ireland (SFI) to S.M. under grant no. SFI/12/RC/2273 to APC Microbiome Institute, the Found of Donations to the Medical Faculty, Umeå University to M-L.H., and a combined medical practice- and research fellowship from the County of Västerbotten to A.Z.. icddr,b is thankful to the donors for their support to its research efforts. icddr,b is also grateful to the Government of Bangladesh, Canada, Sweden and the UK for providing core/unrestricted support. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.