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Obesity is associated with a chronic low-grade inflammation that predisposes to insulin resistance and the development of type 2 diabetes. In this metabolic context, gastrointestinal (GI) candidiasis is common. We recently demonstrated that the PPAR gamma ligand rosiglitazone promotes the clearance of Candida albicans through the activation of alternative M2 macrophage polarization. Here, we evaluated the impact of high fat diet (HFD)-induced obesity and the effect of rosiglitazone (PPAR gamma ligand) or WY14643 (PPAR alpha ligand) both on the phenotypic M1/M2 polarization of peritoneal and cecal tissue macrophages and on the outcome of GI candidiasis. We demonstrated that the peritoneal macrophages and the cell types present in the cecal tissue from HF fed mice present a M2b polarization (TNF-alpha(high), IL-10(high), MR, Dectin-1). Interestingly, rosiglitazone induces a phenotypic M2b-to-M2a (TNF-alpha(low), IL-10(low), MRhigh, Dectin-1(high)) switch of peritoneal macrophages and of the cells present in the cecal tissue. The incapacity of WY14643 to switch this polarization toward M2a state, strongly suggests the specific involvement of PPAR gamma in this mechanism. We showed that in insulin resistant mice, M2b polarization of macrophages present on the site of infection is associated with an increased susceptibility to GI candidiasis, whereas M2a polarization after rosiglitazone treatment favours the GI fungal elimination independently of reduced blood glucose. In conclusion, our data demonstrate a dual benefit of PPAR gamma ligands because they promote mucosal defence mechanisms against GI candidiasis through M2a macrophage polarization while regulating blood glucose level.
Johan Auwerx, Jun Yong Kim, Dongryeol Ryu, Ludger Jan Elzuë Goeminne
Sandrine Gerber, Luca Szabó, Léo Bühler
Henry Markram, Daniel Keller, Jay Coggan, Cyrille Pierre Henri Favreau, Mohameth François Sy, Emmanuelle Logette, Samuel Claude Kerrien, Enrico Scantamburlo, Francesco Casalegno, Anna-Kristin Kaufmann, Pierre-Alexandre Fonta