Inflammation and Cardiovascular Disease (CVD)
A wealth of studies have clearly shown that atherosclerosis is a chronic inflammatory disease. As such, immunomodulatory therapy has been proposed as the next stage for improving prevention of atherosclerotic CVD. Indeed, a recent large human trial (CANTOS) provided proof of concept data that treating inflammation could reduce CV events. Yet, not all immune cells are pro-inflammatory. In fact, several immune cell subsets have anti-inflammatory properties and are atheroprotective. Clearly a more comprehensive understanding of immune mechanisms in atherosclerosis is needed. Our group is actively pursuing both human and murine studies on the role of immune cells in CVD and development of precision and personalized immunomodulation approaches through the following ongoing projects:
1) We have recently discovered that the B-1b B cell subset produces abundant atheroprotective natural IgM to oxidation specific epitopes (OSE) on LDL and protects from diet-induced atherosclerosis in pre-clinical models. We have identified the transcription factor Id3 as a key molecular inhibitor of B-1b cells, IgM to OSE and protection from atherosclerosis. Utilizing a well-characterized clinical cohort at UVA, we have translated these findings to humans and shown that individuals with a single nucleotide polymorphisms in Id3 that leads to reduced functional capacity have increased B-1 cells and IgM to OSE (Circ Res). Projects are ongoing to identify the molecular and cellular mechanisms and key Id3 target genes (RNAseq, ChIPseq, etc.) responsible for mediating these effects in mice and humans and developing ways to modulate these genes.
2) One Id3 target with strong links to CVD is the chemokine receptor CXCR4. Yet, despite GWAS associations supporting this link, a deeper understanding of potential mechanisms and strategic approaches to harness this information for precision immune modulation have been elusive. We have a large cohort of human subjects in whom we have characterized the amount and composition of atherosclerosis in the coronary artery with intravascular ultrasound with virtual histology (IVUS-VH). Utilizing flow cytometry assessment of circulating immune cells from these subjects, we have discovered that the amount of CXCR4 on B-1 cells is significantly inversely associated with the amount of artery plaque and characteristics that are associated with risk for heart attack. Consistent with the anti-inflammatory effect of IgM to OSE, we found a positive association of CXCR4 levels on B-1 cells and IgM to OSE in both mouse and human. This project is part of a Program Project Grant in collaboration with researchers in San Diego and La Jolla. We are also currently combining genetics with nanomedicine to develop personalized approaches for immune strategies targeting B-1 cell chemokine receptor expression.
3) We have previously identified perivascular adipose tissue (PVAT) as a site with abundant immune cells, including B cells, in mice and humans (Frontiers in Physiology). In fact, adipose tissue, including PVAT, is a major site of production of anti-inflammatory IgM to OSE. Given its proximity to arteries, and the strong link between obesity and CVD, we are currently studying the role of PVAT in contributing to CVD. We have identified specific chemokine receptors that mediate B cell trafficking to PVAT and are studying their link to CVD in mice and humans. We are currently performing cutting edge multidimensional profiling of the circulating immune cells in these subjects using mass cytometry (CyTOF) in our subjects with IVUS-VH to identify immune markers associated with PVAT inflammation and CVD in mice and humans.
4) We recently reported (ATVB) that IgE to α-Gal, the primary cause of delayed anaphylaxis to red meat (α-Gal syndrome), was associated with increased atheroma burden and plaques with more unstable features as measured by IVUS-VH in 118 subjects presenting to UVA for coronary artery imaging. In the United States sensitization to α-Gal is recognized as a consequence of bites of the tick Amblyomma americanum. Further studies to expand these findings and identify the mechanisms mediating these effects are ongoing.
Precision Medicine: We have developed the pipeline for high dimensional analysis of human PBMCs to identify unique immunophenotypes associated with disease burden and therapeutic responses. We are applying them to clinical scenarios to aid in the development of personalized approaches to therapy:
1) In a randomized controlled study of subjects with systolic heart failure receiving IL-1β receptor antagonism or placebo.
2) In a longitudinal study of subjects receiving cardiac resynchronization therapy for heart failure.
3) In a longitudinal study of subjects with rheumatoid arthritis receiving DMARDS.
Genotype to Phenotype studies: We have discovered a single nucleotide polymorphism (SNP) in the human inhibitor of differentiation 3 (ID3) gene at rs11574 that results in attenuated ID3 function (Cir Res) and is associated with CVD in 3 distinct human cohorts. We have shown that knockout of the Id3 gene in mice regulates vascular smooth muscle cell (VSMC) proliferation in vitro and in vivo, and that Id3 overexpression reduces VSMC differentiation gene activation. VSMC growth and differentiation are key processes involved in atherogenesis. Ongoing work in the lab is utilizing CRISPR/Cas9 gene editing of human iPSC-derived VSMC to determine the impact of this CV disease-associated SNP on VSMC phenotypes linked to CVD.
La Jolla Institute of Allergy & Immunology (LIAI)
Dr. McNamara's project titled, "B-1A Lymphocytes in Atherosclerosis" hypothesizes that Id3 in B cells is necessary for B-la cell atheroprotection through promoting B-la cell cycle progression and self-renewal resulting in increased levels of atheroprotective natural antibodies such as E06. Our lab is currently studying the molecular and cellular mechanisms mediating these effects. Moreover, we are attempting to translate these novel findings in mice into testable hypotheses in humans with type 2 diabetes (T2DM). Through collaborations with our colleagues in La Jolla, and our human core, we are uniquely poised to test these innovative hypotheses to identify molecular mechanisms regulating atheroprotective B cells in mice and humans, potentially leading to identification of novel biomarkers and novel strategies to bolster innate immune protection against atherosclerosis.
Dr. McNamara directs the Human Phenotyping and Immune Cell Core which provides human and immune cell phenotyping critical to the translation of mechanistic findings into the human model.
The effects of immune cell variations on atherosclerosis in humans represents a poorly understood area of atherogenesis and possible atheroprotection. The goal of the Human Phenotyping and Immune Cell Core is to provide the resources necessary for translation of novel immune mechanisms of atherosclerosis that are well defined in murine models into the human model.
Robert M. Berne Cardiovascular Research Center (aka CVRC)
Department of Cardiovascular Medicine
Cardiovascular Training Grant (CVTG and Facebook)
Bosterbio offers an exclusive 20% discount to the McNamara lab and its associates for ELISA kits.
B cells in adventitia of aged ApoE-/- mice: Aorta tertiary lymphoid organs (ATLOs) develop in adventitia of aorta adjacent to atherosclerotic plaque in aged ApoE-/- mice. Immunofluorescence staining with an anti-CD20 antibody in diseased aorta with lymph node demonstrates B cells in the ATLO and renal lymph node (RLN), but not in the media (M) or plaque (P). Yellow line box (left side) indicates enlarged picture of ATLOs (right side). DAPI used for nuclear staining. L= lumen of aorta, A= adventitia of aorta.
Use of Flow Cytometry Identifies Increased Number of B1b B cells in Mice with specific B cell deletion of Id3. Representative flow cytometry plots from PerC of Id3WT and Id3BKO mice. B-2 cells are defined as CD19+B220high, B-1a cells are defined as CD19highB220mid/lowIgMhighCD5+, B-1b cells are defined as CD19highB220mid/lowIgMhighCD5-
1. Rosenfeld SM, Perry HM, Gonen A, Prohaska TA, Srikakulapu P, Grewal S, Das D, McSkimming C, Taylor AM, Tsimikas S, Bender TP, Witztum JL, McNamara CA. B-1b Cells Secrete Atheroprotecive IgM and Attenuate Atherosclerosis Circ Res. 2015 Jul 17;117(3):e28-39. PMCID: PMC4527334.
2. Kaplan JL, Marshall MA, C McSkimming C, Harmon DB, Garmey JC, Oldham SN, Hallowell P, McNamara CA. Adipocyte progenitor cells initiate monocyte chemoattractant protein-1-mediated macrophage accumulation in visceral adipose tissue. Mol Metab. 2015 Aug 12;4(11):779-94. PMCID: PMC4632113.
3. Harmon DB, Srikakulapu P, Kaplan JL, Oldham SN, McSkimming C, Garmey J, Perry HM, Kirby JL, Prohaska TA, Gonen A, Hallowell P, Schirmer B, Tsimikas S, Taylor AM, Witztum JL, McNamara CA. Protective role for B-1b B Cells and Igm in Obesity-Associated Inflammation, Glucose Intolerance, and Insulin Resistance. Arterioscler Thromb Vasc Biol. 2016 Apr;36(4):682-91. PMCID: PMC4808436.
4. Prasad Srikakulapu, Desheng Hu, Changjun Yin, Sarajo Mohanta, Sai Vineela Bontha, Li Peng, Michael Beer, Christian Weber, Coleen McNamara, Gianluca Grassia, Pasquale Maffia, and Rudolf Manz. Artery Tertiary Lymphoid Organs Control Multi-layered Territorialized Atherosclerosis B Cell Responses in Aged ApoE-/- Mice. Arterioscler Thromb Vasc Biol. 2016 Jun;36(6):1174-85. PMCID: PMC4894775.
5. Cheng HY, Gaddis DE, Wu R, McSkimming C, Haynes LD, Taylor AM, McNamara CA, Sorci-Thomas M, Hedrick CC. Loss of ABCG1 influences regulatory T cell differentiation and atherosclerosis. JCl 2016 Sep 1;126(9):3236-46. PMCID: PMC5004951.
6. Prasad Srikakulapu, Aditi Upadhye, Sam M. Rosenfeld, Melissa A. Marshall, Chantel McSkimming, Alexandra W. Hickman, Ileana S. Mauldin, Gorav Ailawadi, M. Beatriz S. Lopes, Angela M. Taylor and Coleen A. McNamara. Perivascular Adipose Tissue Harbors Atheroprotective IgM-Producing B Cells. Frontiers in Physiology. 2017; 8:719. PMCID: PMC5609437.
7. Kothari H, Nguyen AT, Yang X, Hisada Y, Tsimikas S, Mackman N, Taylor A, McNamara CA. Association of D-dimer with Plaque Characteristics and Plasma Biomarkers of Oxidation-Specific Epitopes in Stable Subjects with Coronary Artery Disease. J Cardiovasc Transl Res. 2018 Jan 17. 9790-4. PMID: 29344841.
8. Gaddis DE, Padgett LE, Wu R, McSkimming C, Romines V, Taylor AM, McNamara CA, Kronenberg M, Crotty S, Thomas MJ, Sorci-Thomas MG, Hedrick CC. Apolipoprotein AI prevents regulatory to follicular helper T cell switching during atherosclerosis. Nat Commun. 2018 Mar 15;9(1):1095. PMCID: PMC5854619.
9. Wilson JM, Nguyen AT, Schuyler AJ, Commins SP, Taylor AM, Platts-Mills TAE, McNamara CA. IgE to the Mammalian Oligosaccharide Galactose-α-1,3-Galactose Is Associated With Increased Atheroma Volume and Plaques With Unstable Characteristics-Brief Report. Arterioscler Thromb Vasc Biol. 2018 Jul;38(7):1665-1669. PMCID: PMC6039405.