Hematopoietic deficiency of miR155 promotes atherosclerotic lesion development in LDLR^−/− mice.

<p>Representative pictures of toluidine blue-stained sections of the aortic root of wildtype (A) and miR155^−/− (B) transplanted mice, magnification 40×. Hematopoietic miR155 deficiency increases plaque area (C) and promotes plaque progression towards more advanced lesions (D, Chi square test p<0.05). * p<0.05, n = 14 wildtypes and 19 miR155−/− mice.</p

Pro-inflammatory effects of miR155 deficiency specifically in resident, hyperlipidemic peritoneal cells.

<p>mRNA was isolated from resident peritoneal cells obtained from wildtype or miR155^−/− transplanted mice after 10 weeks of HC diet feeding. miR155 deficiency decreases IL-10 mRNA expression (A), while increasing IL-6 mRNA expression (B) in these hyperlipidemic peritoneal cells. No differences were found between genotypes on SOCS-1 mRNA expression (C). *p<0.05, n = 9–10/group.</p

Hematopoietic deficiency of miR155 enhances inflammation in atherosclerotic lesions.

<p>(A) Pathological examination of collagen, necrosis, foam cells, inflammatory cells, monocyte adhesion to the plaque and adventitial influx. AU: arbitrary units. (B) collagen content stained by Sirius red staining, (C) Monocyte/macrophage area stained by moma-2, (D) Neutrophil numbers stained by NIMP, (E) Newly recruited macrophages identified by ERMP58 and (F) T cell numbers stained by KT-3 antibody (directed against CD3). Arrowheads indicate positively stained cells. *p<0.05, n = 14 wildtypes and 19 miR155−/− mice.</p

Hematopoietic miR155 deficiency decreases anti-inflammatory IL-10 production in peritoneal macrophages.

<p>IL-10 and IL-12 production by peritoneal macrophages of wildtype transplanted (A) and miR155^−/− transplanted (B) mice. Production of anti-inflammatory IL-10 in peritoneal macrophages of miR155^−/− transplanted mice is reduced (C). *p<0.05, n = 10/group.</p

Plasma lipid levels of mice transplanted with either miR155^−/− or wildtype bone marrow.

<p>Cholesterol (A) and Triglyceride (B) levels measured before the start of HC diet (0 weeks of diet), after 5 weeks of diet and upon sacrifice of the mice (10 weeks of diet). * p<0.05, n = 20/group.</p

Pro-inflammatory blood leukocyte profile in hematopoietic miR155 deficient mice.

<p>(A) Blood lymphocytes profile. B220 for B cells, CD3 for T cells, CD4 T-helper cells and CD8 for cytotoxic T cells. (B) Regulatory T cells identified by CD4⁺CD25⁺ and CD25⁺FoxP3⁺ staining. Representative examples of circulating myeloid cells in wildtype transplanted (C) and miR155^−/− transplanted (D) mice. (E) Number of circulating granulocytes (CD11b⁺Ly6G⁺) and monocytes (CD11b⁺Ly6G⁻), subdivided in Ly6C^hi (inflammatory), Ly6C^low (resident) and Ly6C^med monocytes (F). *p<0.05, n = 10/group.</p

Reprogramming macrophages to an anti‐inflammatory phenotype by helminth antigens reduces murine atherosclerosis

Atherosclerosis is a lipid-driven inflammatory disease of the vessel wall, characterized by the chronic activation of macrophages. We investigated whether the helminth-derived antigens [soluble egg antigens (SEAs)] could modulate macrophage inflammatory responses and protect against atherosclerosis in mice. In bone marrow-derived macrophages, SEAs induce anti-inflammatory macrophages, typified by high levels of IL-10 and reduced secretion of proinflammatory mediators. In hyperlipidemic LDLR-/- mice, SEA treatment reduced plaque size by 44%, and plaques were less advanced compared with PBS-injected littermate controls. The atheroprotective effect of SEAs was found to be mainly independent of cholesterol lowering and T-lymphocyte responses but instead could be attributed to diminished myeloid cell activation. SEAs reduced circulating neutrophils and inflammatory Ly6C(high) monocytes, and macrophages showed high IL-10 production. In line with the observed systemic effects, atherosclerotic lesions of SEA-treated mice showed reduced intraplaque inflammation as inflammatory markers [TNF-, monocyte chemotactic protein 1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and CD68], neutrophil content, and newly recruited macrophages were decreased. We show that SEA treatment protects against atherosclerosis development by dampening inflammatory responses. In the future, helminth-derived components may provide novel opportunities to treat chronic inflammatory diseases, as they diminish systemic inflammation and reduce the activation of immune cells.Wolfs, I. M. J., Stoger, J. L., Goossens, P., Pottgens, C., Gijbels, M. J. J., Wijnands, E., van der Vorst, E. P. C., van Gorp, P., Beckers, L., Engel, D., Biessen, E. A. L., Kraal, G., van Die, I., Donners, M. M. P. C., de Winther, M. P. J. Reprogramming macrophages to an anti-inflammatory phenotype by helminth antigens reduces murine atherosclerosi

Deleting myeloid IL-10 receptor signalling attenuates atherosclerosis in LDLR^-/-mice by altering intestinal cholesterol fluxes

International audienceInflammatory responses and cholesterol homeostasis are interconnected in atherogenesis. Interleukin (IL)-10 is an important anti-inflammatory cytokine, known to suppress atherosclerosis development. However, the specific cell types responsible for the atheroprotective effects of IL-10 remain to be defined and knowledge on the actions of IL-10 in cholesterol homeostasis is scarce. Here we investigated the functional involvement of myeloid IL-10-mediated athero-protection. To do so, bone marrow from IL-10 receptor 1 (IL-10R1) wild-type and myeloid IL-10R1-deficient mice was transplanted to lethally irradiated female LDLR-/- mice. Hereafter, mice were given a high cholesterol diet for 10 weeks after which atherosclerosis development and cholesterol metabolism were investigated. In vitro, myeloid IL-10R1 deficiency resulted in a pro-inflammatory macrophage phenotype. However, in vivo significantly reduced lesion size and severity was observed. This phenotype was associated with lower myeloid cell accumulation and more apoptosis in the lesions. Additionally, a profound reduction in plasma and liver cholesterol was observed upon myeloid IL-10R1 deficiency, which was reflected in plaque lipid content. This decreased hypercholesterolaemia was associated with lowered very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) levels, likely as a response to decreased intestinal cholesterol absorption. In addition, IL-10R1 deficient mice demonstrated substantially higher faecal sterol loss caused by increased non-biliary cholesterol efflux. The induction of this process was linked to impaired ACAT2-mediated esterification of liver and plasma cholesterol. Overall, myeloid cells do not contribute to IL-10-mediated atheroprotection. In addition, this study demonstrates a novel connection between IL-10-mediated inflammation and cholesterol homeostasis in atherosclerosis. These findings make us reconsider IL-10 as a beneficial influence on atherosclerosis