Dataset Information

Deficiency of antigen-presenting cell invariant chain reduces atherosclerosis in mice.

ABSTRACT:

Background

Adaptive immunity and innate immunity play important roles in atherogenesis. Invariant chain (CD74) mediates antigen-presenting cell antigen presentation and T-cell activation. This study tested the hypothesis that CD74-deficient mice have reduced numbers of active T cells and resist atherogenesis.

Methods and results

In low-density lipoprotein receptor-deficient (Ldlr(-/-)) mice, CD74 deficiency (Ldlr(-/-)Cd74(-/-)) significantly reduced atherosclerosis and CD25(+)-activated T cells in the atheromata. Although Ldlr(-/-)Cd74(-/-) mice had decreased levels of plasma immunoglobulin (Ig) G1, IgG2b, and IgG2c against malondialdehyde-modified LDL (MDA-LDL), presumably as a result of impaired antigen-presenting cell function, Ldlr(-/-)Cd74(-/-) mice showed higher levels of anti-MDA-LDL IgM and IgG3. After immunization with MDA-LDL, Ldlr(-/-)Cd74(-/-) mice had lower levels of all anti-MDA-LDL Ig isotypes compared with Ldlr(-/-) mice. As anticipated, only Ldlr(-/-) splenocytes responded to in vitro stimulation with MDA-LDL, producing Th1/Th2 cytokines. Heat shock protein-65 immunization enhanced atherogenesis in Ldlr(-/-) mice, but Ldlr(-/-) Cd74(-/-) mice remained protected. Compared with Ldlr(-/-) mice, Ldlr(-/-)Cd74(-/-) mice had higher anti-MDA-LDL autoantibody titers, fewer lesion CD25(+)-activated T cells, impaired release of Th1/Th2 cytokines from antigen-presenting cells after heat shock protein-65 stimulation, and reduced levels of all plasma anti-heat shock protein-65 Ig isotypes. Cytofluorimetry of splenocytes and peritoneal cavity cells of MDA-LDL- or heat shock protein-65-immunized mice showed increased percentages of autoantibody-producing marginal zone B and B-1 cells in Ldlr(-/-)Cd74(-/-) mice compared with Ldlr(-/-) mice.

Conclusions

Invariant chain deficiency in Ldlr(-/-) mice reduced atherosclerosis. This finding was associated with an impaired adaptive immune response to disease-specific antigens. Concomitantly, an unexpected increase in the number of innate-like peripheral B-1 cell populations occurred, resulting in increased IgM/IgG3 titers to the oxidation-specific epitopes.

SUBMITTER: Sun J

PROVIDER: S-EPMC2927799 | biostudies-literature | 2010 Aug

REPOSITORIES: biostudies-literature

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Publications

Deficiency of antigen-presenting cell invariant chain reduces atherosclerosis in mice.

Sun Jiusong J Hartvigsen Karsten K Chou Meng-Yun MY Zhang Yadong Y Sukhova Galina K GK Zhang Jie J Lopez-Ilasaca Marco M Diehl Cody J CJ Yakov Niva N Harats Dror D George Jacob J George Jacob J Witztum Joseph L JL Libby Peter P Ploegh Hidde H Shi Guo-Ping GP

Circulation 20100809 8

<h4>Background</h4>Adaptive immunity and innate immunity play important roles in atherogenesis. Invariant chain (CD74) mediates antigen-presenting cell antigen presentation and T-cell activation. This study tested the hypothesis that CD74-deficient mice have reduced numbers of active T cells and resist atherogenesis.<h4>Methods and results</h4>In low-density lipoprotein receptor-deficient (Ldlr(-/-)) mice, CD74 deficiency (Ldlr(-/-)Cd74(-/-)) significantly reduced atherosclerosis and CD25(+)-act ...[more]

PMID: 20697023

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Project description:Extracellular adenosine-5'-triphosphate (ATP) acts as an import signaling molecule mediating inflammation via purinergic P2 receptors. ATP binds to the purinergic receptor P2X4 and promotes inflammation via increased expression of pro-inflammatory cytokines. Because of the central role of inflammation, we assumed a functional contribution of the ATP-P2X4-axis in atherosclerosis. Expression of P2X4 was increased in atherosclerotic aortic arches from low-density lipoprotein receptor-deficient mice being fed a high cholesterol diet as assessed by real-time polymerase chain reaction and immunohistochemistry. To investigate the functional role of P2X4 in atherosclerosis, P2X4-deficient mice were crossed with low-density lipoprotein receptor-deficient mice and fed high cholesterol diet. After 16 weeks, P2X4-deficient mice developed smaller atherosclerotic lesions compared to P2X4-competent mice. Furthermore, intravital microscopy showed reduced ATP-induced leukocyte rolling at the vessel wall in P2X4-deficient mice. Mechanistically, we found a reduced RNA expression of CC chemokine ligand 2 (CCL-2), C-X-C motif chemokine-1 (CXCL-1), C-X-C motif chemokine-2 (CXCL-2), Interleukin-6 (IL-6) and tumor necrosis factor α (TNFα) as well as a decreased nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3)-inflammasome priming in atherosclerotic plaques from P2X4-deficient mice. Moreover, bone marrow derived macrophages isolated from P2X4-deficient mice revealed a reduced ATP-mediated release of CCL-2, CC chemokine ligand 5 (CCL-5), Interleukin-1β (IL-1β) and IL-6. Additionally, P2X4-deficient mice shared a lower proportion of pro-inflammatory Ly6Chigh monocytes and a higher proportion of anti-inflammatory Ly6Clow monocytes, and expressend less endothelial VCAM-1. Finally, increased P2X4 expression in human atherosclerotic lesions from carotid endarterectomy was found, indicating the importance of potential implementations of this study's findings for human atherosclerosis. Collectively, P2X4 deficiency reduced experimental atherosclerosis, plaque inflammation and inflammasome priming, pointing to P2X4 as a potential therapeutic target in the fight against atherosclerosis.

Project description:ObjectiveAngiotensin II (AngII) infusion profoundly increases activity of calpains, calcium-dependent neutral cysteine proteases, in mice. Pharmacological inhibition of calpains attenuates AngII-induced aortic medial macrophage accumulation, atherosclerosis, and abdominal aortic aneurysm in mice. However, the precise functional contribution of leukocyte-derived calpains in AngII-induced vascular pathologies has not been determined. The purpose of this study was to determine whether calpains expressed in bone marrow (BM)-derived cells contribute to AngII-induced atherosclerosis and aortic aneurysms in hypercholesterolemic mice.Approach and resultsTo study whether leukocyte calpains contributed to AngII-induced aortic pathologies, irradiated male low-density lipoprotein receptor(-/-) mice were repopulated with BM-derived cells that were either wild-type or overexpressed calpastatin, the endogenous inhibitor of calpains. Mice were fed a fat-enriched diet and infused with AngII (1000 ng/kg per minute) for 4 weeks. Overexpression of calpastatin in BM-derived cells significantly attenuated AngII-induced atherosclerotic lesion formation in aortic arches, but had no effect on aneurysm formation. Using either BM-derived cells from calpain-1-deficient mice or mice with leukocyte-specific calpain-2 deficiency generated using cre-loxP recombination technology, further studies demonstrated that independent deficiency of either calpain-1 or -2 in leukocytes modestly attenuated AngII-induced atherosclerosis. Calpastatin overexpression significantly attenuated AngII-induced inflammatory responses in macrophages and spleen. Furthermore, calpain inhibition suppressed migration and adhesion of macrophages to endothelial cells in vitro. Calpain inhibition also significantly decreased hypercholesterolemia-induced atherosclerosis in the absence of AngII.ConclusionsThe present study demonstrates a pivotal role for BM-derived calpains in mediating AngII-induced atherosclerosis by influencing macrophage function.

Dataset Information

Deficiency of antigen-presenting cell invariant chain reduces atherosclerosis in mice.

Background

Methods and results

Conclusions

Publications

Deficiency of antigen-presenting cell invariant chain reduces atherosclerosis in mice.

Similar Datasets

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