Modeling the role of peroxisome proliferator-activated receptor γ and microRNA-146 in mucosal immune responses to Clostridium difficile.
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.
Nutritional Immunology and Molecular Medicine Laboratory, Virginia Bioinformatics Institute, Virginia Tech, Blacksburg, VA, USA.
Monica
M
Viladomiu
Raquel
R
Hontecillas
Mireia
M
Pedragosa
Adria
A
Carbo
Stefan
S
Hoops
Pawel
P
Michalak
Katarzyna
K
Michalak
Richard L
RL
Guerrant
James K
JK
Roche
Cirle A
CA
Warren
Josep
J
Bassaganya-Riera
D000704:Analysis of Variance; D000818:Animals; D001483:Base Sequence; D016360:Clostridioides difficile / Q000276:immunology*; D003106:Colon / Q000276:immunology / Q000473:pathology*; D017931:DNA Primers / Q000235:genetics; D004761:Enterocolitis, Pseudomembranous / Q000276:immunology* / Q000473:pathology; D005786:Gene Expression Regulation / Q000276:immunology*; D059014:High-Throughput Nucleotide Sequencing; D006652:Histological Techniques; D016130:Immunophenotyping; D016753:Interleukin-10 / Q000276:immunology; D020381:Interleukin-17 / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000235:genetics / Q000276:immunology*; D018448:Models, Immunological; D008969:Molecular Sequence Data; D047495:PPAR gamma / Q000819:agonists / Q000276:immunology*; D000077205:Pioglitazone; D060888:Real-Time Polymerase Chain Reaction; D058504:Th17 Cells / Q000276:immunology; D045162:Thiazolidinediones / Q000494:pharmacology
D017931:DNA Primers; D020381:Interleukin-17; D035683:MicroRNAs; C534190:Mirn146 microRNA, mouse; D047495:PPAR gamma; D045162:Thiazolidinediones; D016753:Interleukin-10; D000077205:Pioglitazone