Modeling the role of peroxisome proliferator-activated receptor γ and microRNA-146 in mucosal immune responses to Clostridium difficile

PLoS One. 2012;7(10):e47525. doi: 10.1371/journal.pone.0047525. Epub 2012 Oct 11.

Abstract

Clostridium difficile is an anaerobic bacterium that has re-emerged as a facultative pathogen and can cause nosocomial diarrhea, colitis or even death. Peroxisome proliferator-activated receptor (PPAR) γ has been implicated in the prevention of inflammation in autoimmune and infectious diseases; however, its role in the immunoregulatory mechanisms modulating host responses to C. difficile and its toxins remains largely unknown. To characterize the role of PPARγ in C. difficile-associated disease (CDAD), immunity and gut pathology, we used a mouse model of C. difficile infection in wild-type and T cell-specific PPARγ null mice. The loss of PPARγ in T cells increased disease activity and colonic inflammatory lesions following C. difficile infection. Colonic expression of IL-17 was upregulated and IL-10 downregulated in colons of T cell-specific PPARγ null mice. Also, both the loss of PPARγ in T cells and C. difficile infection favored Th17 responses in spleen and colonic lamina propria of mice with CDAD. MicroRNA (miRNA)-sequencing analysis and RT-PCR validation indicated that miR-146b was significantly overexpressed and nuclear receptor co-activator 4 (NCOA4) suppressed in colons of C. difficile-infected mice. We next developed a computational model that predicts the upregulation of miR-146b, downregulation of the PPARγ co-activator NCOA4, and PPARγ, leading to upregulation of IL-17. Oral treatment of C. difficile-infected mice with the PPARγ agonist pioglitazone ameliorated colitis and suppressed pro-inflammatory gene expression. In conclusion, our data indicates that miRNA-146b and PPARγ activation may be implicated in the regulation of Th17 responses and colitis in C. difficile-infected mice.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Animals
  • Base Sequence
  • Clostridium difficile / immunology*
  • Colon / immunology
  • Colon / pathology*
  • DNA Primers / genetics
  • Enterocolitis, Pseudomembranous / immunology*
  • Enterocolitis, Pseudomembranous / pathology
  • Gene Expression Regulation / immunology*
  • High-Throughput Nucleotide Sequencing
  • Histological Techniques
  • Immunophenotyping
  • Interleukin-10 / immunology
  • Interleukin-17 / immunology
  • Mice
  • Mice, Inbred C57BL
  • MicroRNAs / genetics
  • MicroRNAs / immunology*
  • Models, Immunological*
  • Molecular Sequence Data
  • PPAR gamma / agonists
  • PPAR gamma / immunology*
  • Pioglitazone
  • Real-Time Polymerase Chain Reaction
  • Th17 Cells / immunology
  • Thiazolidinediones / pharmacology

Substances

  • DNA Primers
  • Interleukin-17
  • MicroRNAs
  • Mirn146 microRNA, mouse
  • PPAR gamma
  • Thiazolidinediones
  • Interleukin-10
  • Pioglitazone