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Mucosal Immunol. 2017 Sep;10(5):1224-1236. doi: 10.1038/mi.2016.135. Epub 2017 Jan 25.

Regulation of IL-12p40 by HIF controls Th1/Th17 responses to prevent mucosal inflammation.

Author information

1
School of Biomedical Sciences and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia.
2
Hunter Medical Research Institute, New Lambton Heights, New South Wales, Australia.
3
Priority Research Centre for Digestive Health and Neurogastroenterology, University of Newcastle, Newcastle, New South Wales, Australia.
4
School of Medicine, Public Health, University of Newcastle, Newcastle, New South Wales, Australia.
5
Royal Brisbane and Women's Hospital, Brisbane, School of Medicine, University of Queensland, Brisbane, Queensland, Australia.
6
QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.

Abstract

Intestinal inflammatory lesions are inherently hypoxic, due to increased metabolic demands created by cellular infiltration and proliferation, and reduced oxygen supply due to vascular damage. Hypoxia stabilizes the transcription factor hypoxia-inducible factor-1α (HIF) leading to a coordinated induction of endogenously protective pathways. We identified IL12B as a HIF-regulated gene and aimed to define how the HIF-IL-12p40 axis influenced intestinal inflammation. Intestinal lamina propria lymphocytes (LPL) were characterized in wild-type and IL-12p40-/- murine colitis treated with vehicle or HIF-stabilizing prolyl-hydroxylase inhibitors (PHDi). IL12B promoter analysis was performed to examine hypoxia-responsive elements. Immunoblot analysis of murine and human LPL supernatants was performed to characterize the HIF/IL-12p40 signaling axis. We observed selective induction of IL-12p40 following PHDi-treatment, concurrent with suppression of Th1 and Th17 responses in murine colitis models. In the absence of IL-12p40, PHDi-treatment was ineffective. Analysis of the IL12B promoter identified canonical HIF-binding sites. HIF stabilization in LPLs resulted in production of IL-12p40 homodimer which was protective against colitis. The selective induction of IL-12p40 by HIF-1α leads to a suppression of mucosal Th1 and Th17 responses. This HIF-IL12p40 axis may represent an endogenously protective mechanism to limit the progression of chronic inflammation, shifting from pro-inflammatory IL-12p70 to an antagonistic IL-12p40 homodimer.

PMID:
28120851
DOI:
10.1038/mi.2016.135
[Indexed for MEDLINE]

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