Assessing the impact of an antigen-specific antibody response on atherosclerosis development in mice.

The antibody immune response plays a critical role in atherosclerosis. Here, we present a protocol for assessing the impact of an antigen-specific germinal center antibody response on atherosclerosis development, using a pro-atherogenic mouse model deficient for the production of germinal-center-derived antibodies. We describe steps for bone marrow transfer from donor mice into irradiated recipient mice. We then detail immunization of mouse chimeras with atheroprotective malondialdehyde low-density lipoprotein during high-fat diet feeding and atherosclerosis burden analysis. For complete details on the use and execution of this protocol, please refer to Martos-Folgado et al. (2022).1.We thank all members of the B Cell Biology Laboratory for useful discussions. A.D.M.M. is funded by ‘‘la Caixa’’ Foundation HR17-00247, I.M.-F. was a fellow of the research training program funded by Ministerio de Economía y Competitividad (SVP-2014-068216), A.R-R. is a fellow of the research training program funded by Ministerio de Ciencia, Innovacio´ n y Universidades (PRE2020-091873), and A.R. is supported by Centro Nacional de Investigaciones Cardiovasculares (CNIC). The project leading to these results has received funding from ‘‘la Caixa’’ Foundation under the project code HR17-00247 and HR22-0253 and from SAF2016-75511-R and PID2019-106773RB-I00/AEI/ 10.13039/501100011033 grants to A.R.R. (Plan Estatal de Investigación Científica y Técnica y de Innovación 2013–2016 Programa Estatal de I+D+i Orientada a los Retos de la Sociedad Retos Investigación: Proyectos I + D + i 2016, Ministerio de Economía, Industria y Competitividad) and co-funding by Fondo Europeo de Desarrollo Regional (FEDER). The CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the Ministerio de Ciencia e Innovación (MCIN), and the Pro CNIC Foundation and is a Severo Ochoa institute (CEX2020-001041-S grant funded by MCIN/AEI/ 10.13039/501100011033).S

ALDH4A1 is an atherosclerosis auto-antigen targeted by protective antibodies

Cardiovascular disease (CVD) is the leading cause of mortality in the world, with most CVD-related deaths resulting from myocardial infarction or stroke. The main underlying cause of thrombosis and cardiovascular events is atherosclerosis, an inflammatory disease that can remain asymptomatic for long periods. There is an urgent need for therapeutic and diagnostic options in this area. Atherosclerotic plaques contain autoantibodies, and there is a connection between atherosclerosis and autoimmunity. However, the immunogenic trigger and the effects of the autoantibody response during atherosclerosis are not well understood. Here we performed high-throughput single-cell analysis of the atherosclerosis-associated antibody repertoire. Antibody gene sequencing of more than 1,700 B cells from atherogenic Ldlr and control mice identified 56 antibodies expressed by in-vivo-expanded clones of B lymphocytes in the context of atherosclerosis. One-third of the expanded antibodies were reactive against atherosclerotic plaques, indicating that various antigens in the lesion can trigger antibody responses. Deep proteomics analysis identified ALDH4A1, a mitochondrial dehydrogenase involved in proline metabolism, as a target antigen of one of these autoantibodies, A12. ALDH4A1 distribution is altered during atherosclerosis, and circulating ALDH4A1 is increased in mice and humans with atherosclerosis, supporting the potential use of ALDH4A1 as a disease biomarker. Infusion of A12 antibodies into Ldlr mice delayed plaque formation and reduced circulating free cholesterol and LDL, suggesting that anti-ALDH4A1 antibodies can protect against atherosclerosis progression and might have therapeutic potential in CVD.Ministerio de Economía y Competitividad (SVP-2014-068289); P.D. was supported by an AECC grant (AIO 2012, Ayudas a Investigadores en Oncología 2012); A.S.-B. is a Juan de la Cierva researcher (IJC2018-035279-I); I.M.-F. was a fellow of the research training program funded by Ministerio de Economía y Competitividad (SVP-2014-068216); and A.R.R. and J.V. are supported by Centro Nacional de Investigaciones Cardiovasculares (CNIC). The project leading to these results has received funding from la Caixa Banking Foundation under the project code HR17-00247 and from SAF2016-75511-R and PID2019-106773RB-I00 grants to A.R.R. (Plan Estatal de Investigación Científica y Técnica y de Innovación 2013–201

Aging-Associated miR-217 Aggravates Atherosclerosis and Promotes Cardiovascular Dysfunction.

microRNAs are master regulators of gene expression with essential roles in virtually all biological processes. miR-217 has been associated with aging and cellular senescence, but its role in vascular disease is not understood. Approach and Results: We have used an inducible endothelium-specific knock-in mouse model to address the role of miR-217 in vascular function and atherosclerosis. miR-217 reduced NO production and promoted endothelial dysfunction, increased blood pressure, and exacerbated atherosclerosis in proatherogenic apoE-/- mice. Moreover, increased endothelial miR-217 expression led to the development of coronary artery disease and altered left ventricular heart function, inducing diastolic and systolic dysfunction. Conversely, inhibition of endogenous vascular miR-217 in apoE-/- mice improved vascular contractility and diminished atherosclerosis. Transcriptome analysis revealed that miR-217 regulates an endothelial signaling hub and downregulates a network of eNOS (endothelial NO synthase) activators, including VEGF (vascular endothelial growth factor) and apelin receptor pathways, resulting in diminished eNOS expression. Further analysis revealed that human plasma miR-217 is a biomarker of vascular aging and cardiovascular risk. Our results highlight the therapeutic potential of miR-217 inhibitors in aging-related cardiovascular disease.V.G. de Yébenes was supported by Ramón y Cajal grant RYC-2009-04503 and AECC foundation grant INVES18013GARC and by the Universidad Complutense de Madrid. S.M. Mur and A.R. Ramiro are supported by Centro Nacional de Investigaciones Cardiovasculares (CNIC) funding. A.R. Ramiro was supported by the Spanish Ministerio de Ciencia e Innovación (PID2019-107551RB-I00), the Spanish Ministerio de Economía, Industria y Competitividad (SAF2013-42767-R and SAF2016-75511-R), and the European Research Council StG BCLYM. M. Salaices was supported by the Ministerio de Ciencia e Innovación (SAF2016-80305P) and with J. Miguel Redondo by Instituto de Salud Carlos III (CIBER de Enfermedades Cardiovasculares, CB16/11/00286 and CB16/11/00264) and Comunidad de Madrid (B2017/BMD-3676). V.G. de Yébenes was supported by Ministerio de Ciencia e Innovación (PID2019-107551RB-I00). Further support was provided by the European Social Fund and the European Regional Development Fund “A Way to Build Europe.” The CNIC is supported by Ministerio de Ciencia, Innovacion y Universidades, and the Pro CNIC Foundation and is a Severo Ochoa Center of Excellence (SEV-2015-0505).S

Deciphering antibody-mediated atheroprotection to MDA-LDL

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Medicina, Departamento de Bioquímica. Fecha de Lectura: 05-11-2021Esta tesis tiene embargado el acceso al texto completo hasta el 05-05-2023Atherosclerosis is a chronic inflammatory disease of the arteries that underlies the majority of cardiovascular events. Both innate and adaptive arms of immunity are involved in atherosclerosis initiation and progression. Neo-antigens resulting from endogenous modification of self-components are believed to be the main trigger for the adaptive immune response in atherosclerosis. The most paradigmatic of such neo-antigens are oxidized forms of LDL, and particularly, MDA-LDL. Indeed, immunization of pro-atherogenic mice and rabbits with MDA-LDL is atheroprotective. However, the immune response to MDA-LDL and the mechanisms responsible for this atheroprotection are not well understood. In this thesis, we have assessed the role of germinal center-derived antibodies in atherosclerosis and in MDA-LDL-driven atheroprotection. We have found that immunization of mice with MDA-LDL gives rise to memory B cells, IgG1 switched plasma cells and anti-MDA-LDL antibodies. Additionally, we have found that a fraction of antibodies generated upon MDA-LDL immunization recognize epitopes unique to MDA-LDL neo-antigen. High-throughput single cell immunoglobulin sequencing has revealed that MDA-LDL immunoglobulin repertoire is characterized by highly mutated antibodies. Thus, our data suggest that MDA-LDL behaves as a T-dependent antigen. To analyze the role of germinal center-derived antibodies in atherosclerosis, we have generated a mouse model lacking germinal center-derived plasma cells by conditional deletion of Blimp1. We have found that Blimp1-deficient mice show altered germinal center dynamics. Furthermore, Blimp1-deficient pro-atherogenic chimeras show accelerated atherosclerosis, suggesting an atheroprotective role of germinal center-derived antibodies in atherosclerosis. Finally, we have found that MDA-LDL immunization does not promote atheroprotection in mice lacking Blimp1, therefore indicating that germinal center-derived antibodies are required for MDA-LDL-driven atheroprotection. These findings support the idea that MDA-LDL-based vaccines could potentially be used for the prevention or treatment of atherosclerosi

MDA-LDL vaccination induces athero-protective germinal-center-derived antibody responses.

Atherosclerosis is a chronic inflammatory disease of the arteries that can lead to thrombosis, infarction, and stroke and is the leading cause of mortality worldwide. Immunization of pro-atherogenic mice with malondialdehyde-modified low-density lipoprotein (MDA-LDL) neo-antigen is athero-protective. However, the immune response to MDA-LDL and the mechanisms responsible for this athero-protection are not completely understood. Here, we find that immunization of mice with MDA-LDL elicits memory B cells, plasma cells, and switched anti-MDA-LDL antibodies as well as clonal expansion and affinity maturation, indicating that MDA-LDL triggers a bona fide germinal center antibody response. Further, Prdm1fl/flAicda-Cre+/kiLdlr-/- pro-atherogenic chimeras, which lack germinal center-derived plasma cells, show accelerated atherosclerosis. Finally, we show that MDA-LDL immunization is not athero-protective in mice lacking germinal-center-derived plasma cells. Our findings give further support to the development of MDA-LDL-based vaccines for the prevention or treatment of atherosclerosis.We thank all members of the B Cell Biology Laboratory for useful discussions, A. Rodriguez-Ronchel for the design of the graphical abstract, V.G. de Ye´benes for critical reading of the manuscript, and V. Labrador for help with microscopy and image analysis. I.M.-F. and C.L. were fellows of the research training program funded by Ministerio de Economı´a y Competitividad (SVP-2014-068216 and SVP-2014-068289, respectively), A.d.M.M. is funded by ‘‘la Caixa’’ Foundation HR17–00247, and A.R.R. was supported by Centro Nacional de Investigaciones Cardiovasculares (CNIC). The project leading to these results has received funding from la Caixa Banking Foundation under the project code HR17-00247 and from SAF2016-75511-R and PID2019-106773RB-I00/AEI/10.13039/501100 011033 grants to A.R.R. (Plan Estatal de Investigacio´ n Cientı´fica y Te´ cnica y de Innovacio´ n 2013–2016 Programa Estatal de I+D+i Orientada a los Retos de la Sociedad Retos Investigacio´ n: Proyectos I + D + i 2016, Ministerio de Economı´a,Industria y Competitividad) and co-funding by Fondo Europeo de Desarrollo Regional (FEDER). CIBERCV (J.L.M.-V.) and CIBERDEM (J.C.E.-G.) are Instituto de Salud Carlos III projects. The CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the Ministerio de Ciencia e Innovacio´ n (MCIN), and the Pro CNIC Foundation and is a Severo Ochoa institute (CEX2020-001041-S grant funded by MCIN/AEI/10.13039/501100011033).S

Aging-Associated miR-217 Aggravates Atherosclerosis and Promotes Cardiovascular Dysfunction

microRNAs are master regulators of gene expression with essential roles in virtually all biological processes. miR-217 has been associated with aging and cellular senescence, but its role in vascular disease is not understood. Approach and Results: We have used an inducible endothelium-specific knock-in mouse model to address the role of miR-217 in vascular function and atherosclerosis. miR-217 reduced NO production and promoted endothelial dysfunction, increased blood pressure, and exacerbated atherosclerosis in proatherogenic apoE-/- mice. Moreover, increased endothelial miR-217 expression led to the development of coronary artery disease and altered left ventricular heart function, inducing diastolic and systolic dysfunction. Conversely, inhibition of endogenous vascular miR-217 in apoE-/- mice improved vascular contractility and diminished atherosclerosis. Transcriptome analysis revealed that miR-217 regulates an endothelial signaling hub and downregulates a network of eNOS (endothelial NO synthase) activators, including VEGF (vascular endothelial growth factor) and apelin receptor pathways, resulting in diminished eNOS expression. Further analysis revealed that human plasma miR-217 is a biomarker of vascular aging and cardiovascular risk. Our results highlight the therapeutic potential of miR-217 inhibitors in aging-related cardiovascular disease.V.G. de Yébenes was supported by Ramón y Cajal grant RYC-2009-04503 and AECC foundation grant INVES18013GARC and by the Universidad Complutense de Madrid. S.M. Mur and A.R. Ramiro are supported by Centro Nacional de Investigaciones Cardiovasculares (CNIC) funding. A.R. Ramiro was supported by the Spanish Ministerio de Ciencia e Innovación (PID2019-107551RB-I00), the Spanish Ministerio de Economía, Industria y Competitividad (SAF2013-42767-R and SAF2016-75511-R), and the European Research Council StG BCLYM. M. Salaices was supported by the Ministerio de Ciencia e Innovación (SAF2016-80305P) and with J. Miguel Redondo by Instituto de Salud Carlos III (CIBER de Enfermedades Cardiovasculares, CB16/11/00286 and CB16/11/00264) and Comunidad de Madrid (B2017/BMD-3676). V.G. de Yébenes was supported by Ministerio de Ciencia e Innovación (PID2019-107551RB-I00). Further support was provided by the European Social Fund and the European Regional Development Fund “A Way to Build Europe.” The CNIC is supported by Ministerio de Ciencia, Innovacion y Universidades, and the Pro CNIC Foundation and is a Severo Ochoa Center of Excellence (SEV-2015-0505).S