Influence of Il-10 deficiency on mastocyte phenotype, intestinal microbiota and immune response in a murine model.

Student thesis: Doctoral thesis

Abstract

Mast cells (MC) can participate in the response to microorganisms by various pattern recognition receptors (PRRs). After their activation through these receptors, MC can orchestrate a response by secreting immunological mediators such as cytokines. Among these, interleukin 10 (IL-10) is an important cytokine due to its immunomodulatory characteristics, as well as its ability to regulate the expression of MC proteases. Additionally, thanks to the existence of genetically modified murine models, such as IL-10 deficient (IL-10-/-) mice that develop colitis spontaneously, it is possible to investigate the potential role of IL-10 in MC response to activation with antigens of different microorganisms. On the other hand, the use of this animal model allows investigating the influence of this cytokine on the composition of the intestinal microbiota. This work has explored the functional role of IL-10 in differentiated MC in vitro, as well as the effects of IL-10 deficiency on the composition of the microbiota and the expression of factors related to the immune response, before (6 weeks) and at the onset (20 weeks) of colitis. For this purpose, the effect of IL-10 deficiency has been characterized on MC of different phenotype and after its activation via PRRs. Additionally, the effect produced by the lack of IL-10 on the microbiota composition, the expression of TLRs and proinflammatory cytokines, as well as the production of luminal IgA, in the same stages and after antibiotics treatment was evaluated. The results obtained indicated that the IL-10 deficiency produced different effects depending on the MC phenotype, age and type of PRR ligand. Thus, in the absence of IL-10, mucosal-like MC (MLMC) showed lower expression of TLR4 and NOD2 at week 6 and TLR7 at week 20. In addition, both MC phenotypes (mucosa and connective), showed a lower secretion of IL-6 and TNFα after TLR2 activation. The TLR4 and TLR7 activation in MLMC generated a lower secretion of IL-6 at week 6, while MLMC secreted less TNFα at week 20. Finally, after NOD2 stimulation, no cytokine secretion was observed in any of the MC phenotypes. On the other hand, it was observed that in IL-10-/- animals there are factors that potentially favor the development of colitis. Thus, IL-10-/- mice at week 6 showed representatives of Verrucomicrobia phylum and a lower relative abundance of Rikenellaceae and Lachnospiraceae taxa. Meanwhile at week 20 in IL-10-/- mice, microorganisms of the phylum TM7 were observed, as well as, a lower expression of IL-1β, IL-6, TLR6, -7 and -8, and an increase of TNFα and IgA. Additionally, the use of antibiotics before the development of colitis induced a decrease in diversity and a restructuring of the microbiota, together with a decrease in TLRs and cytokines expression, and a lower production of luminal IgA. In summary, these findings provide new insights on the role of MC and IL-10 in the host-microorganism interaction. They show how the IL-10 deficiency can affect the microbiota composition and the expression of factors associated with the immune response. And they suggest that early modification of the microbiota through the use of antibiotics in genetically susceptible individuals could alter the colitis progression.
Date of Award18 Sept 2018
Original languageUndefined/Unknown
SupervisorPatrocinio Vergara Esteras (Director) & Joan Antoni Férnandez Blanco (Director)

Keywords

  • Mast cells
  • Inflammatory bowel disease

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