title: IL-4Ralpha-independent expression of mannose receptor and Ym1 by macrophages depends on their IL-10 responsiveness.
abstract: IL-4Ralpha-dependent responses are essential for granuloma formation and host survival during acute schistosomiasis. Previously, we demonstrated that mice deficient for macrophage-specific IL-4Ralpha (LysM(cre)Il4ra(-/lox)) developed increased hepatotoxicity and gut inflammation; whereas inflammation was restricted to the liver of mice lacking T cell-specific IL-4Ralpha expression (iLck(cre)Il4ra(-/lox)). In the study presented here we further investigated their role in liver granulomatous inflammation. Frequencies and numbers of macrophage, lymphocyte or granulocyte populations, as well as Th1/Th2 cytokine responses were similar in Schistosoma mansoni-infected LysM(cre)Il4ra(-/lox) liver granulomas, when compared to Il4ra(-/lox) control mice. In contrast, a shift to Th1 responses with high IFN-gamma and low IL-4, IL-10 and IL-13 was observed in the severely disrupted granulomas of iLck(cre)Il4ra(-/lox) and Il4ra(-/-) mice. As expected, alternative macrophage activation was reduced in both LysM(cre)Il4ra(-/lox) and iLck(cre)Il4ra(-/lox) granulomas with low arginase 1 and heightened nitric oxide synthase RNA expression in granuloma macrophages of both mouse strains. Interestingly, a discrete subpopulation of SSC(high)CD11b+I-A/I-E(high)CD204+ macrophages retained expression of mannose receptor (MMR) and Ym1 in LysM(cre)Il4ra(-/lox) but not in iLck(cre)Il4ra(-/lox) granulomas. While aaMphi were in close proximity to the parasite eggs in Il4ra(-/lox) control mice, MMR+Ym1+ macrophages in LysM(cre)Il4ra(-/lox) mice were restricted to the periphery of the granuloma, indicating that they might have different functions. In vivo IL-10 neutralisation resulted in the disappearance of MMR+Ym1+ macrophages in LysM(cre)Il4ra(-/lox) mice. Together, these results show that IL-4Ralpha-responsive T cells are essential to drive alternative macrophage activation and to control granulomatous inflammation in the liver. The data further suggest that in the absence of macrophage-specific IL-4Ralpha signalling, IL-10 is able to drive mannose receptor- and Ym1-positive macrophages, associated with control of hepatic granulomatous inflammation.
authors.affiliation: International Centre for Genetic Engineering and Biotechnology (ICGEB), University of Cape Town, Cape Town, South Africa.
authors.forename: Benjamin G
authors.initials: BG
authors.lastname: Dewals
authors.forename: Reece G
authors.initials: RG
authors.lastname: Marillier
authors.forename: Jennifer C
authors.initials: JC
authors.lastname: Hoving
authors.forename: Mosiuoa
authors.initials: M
authors.lastname: Leeto
authors.forename: Anita
authors.initials: A
authors.lastname: Schwegmann
authors.forename: Frank
authors.initials: F
authors.lastname: Brombacher
mesh_terms: D000818:Animals; D005260:Female; D006099:Granuloma / Q000276:immunology / Q000473:pathology; D016753:Interleukin-10 / Q000378:metabolism*; D037102:Lectins / Q000096:biosynthesis*; D037181:Lectins, C-Type / Q000096:biosynthesis*; D008099:Liver / Q000276:immunology / Q000473:pathology; D008262:Macrophage Activation; D008264:Macrophages / Q000276:immunology* / Q000378:metabolism; D008297:Male; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins / Q000096:biosynthesis*; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D011956:Receptors, Cell Surface / Q000096:biosynthesis* / Q000172:deficiency / Q000276:immunology*; D012550:Schistosoma mansoni / Q000276:immunology*; D012555:Schistosomiasis mansoni / Q000276:immunology* / Q000473:pathology; D013601:T-Lymphocytes / Q000276:immunology; D001619:beta-N-Acetylhexosaminidases / Q000096:biosynthesis*; D053662:Interleukin-4 Receptor alpha Subunit
chemical_list: D016753:Interleukin-10; D037102:Lectins; D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D011956:Receptors, Cell Surface; D001619:beta-N-Acetylhexosaminidases; C504002:Il4ra protein, mouse; D053662:Interleukin-4 Receptor alpha Subunit; C429541:Chil3 protein, mouse