Deletion of Macrophage Vitamin D Receptor Promotes Insulin Resistance and Monocyte Cholesterol Transport to Accelerate Atherosclerosis in Mice

Intense effort has been devoted to understanding predisposition to chronic systemic inflammation because it contributes to cardiometabolic disease. We demonstrate that deletion of the macrophage vitamin D receptor (VDR) in mice (KODMAC) is sufficient to induce insulin resistance by promoting M2 macrophage accumulation in the liver as well as increasing cytokine secretion and hepatic glucose production. Moreover, VDR deletion increases atherosclerosis by enabling lipid-laden M2 monocytes to adhere, migrate, and carry cholesterol into the atherosclerotic plaque and by increasing macrophage cholesterol uptake and esterification. Increased foam cell formation results from lack of VDR-SERCA2b interaction, causing SERCA dysfunction, activation of ER stress-CaMKII-JNKp-PPARγ signaling, and induction of the scavenger receptors CD36 and SR-A1. Bone marrow transplant of VDR-expressing cells into KODMAC mice improved insulin sensitivity, suppressed atherosclerosis, and decreased foam cell formation. The immunomodulatory effects of vitamin D in macrophages are thus critical in diet-induced insulin resistance and atherosclerosis in mice

The St. Louis African American health-heart study: methodology for the study of cardiovascular disease and depression in young-old African Americans

BACKGROUND: Coronary artery disease (CAD) is a major cause of death and disability worldwide. Depression has complex bidirectional adverse associations with CAD, although the mechanisms mediating these relationships remain unclear. Compared to European Americans, African Americans (AAs) have higher rates of morbidity and mortality from CAD. Although depression is common in AAs, its role in the development and features of CAD in this group has not been well examined. This project hypothesizes that the relationships between depression and CAD can be explained by common physiological pathways and gene-environment interactions. Thus, the primary aims of this ongoing project are to: a) determine the prevalence of CAD and depression phenotypes in a population-based sample of community-dwelling older AAs; b) examine the relationships between CAD and depression phenotypes in this population; and c) evaluate genetic variants from serotoninP and inflammatory pathways to discover potential gene-depression interactions that contribute significantly to the presence of CAD in AAs. METHODS/DESIGN: The St. Louis African American Health (AAH) cohort is a population-based panel study of community-dwelling AAs born in 1936–1950 (inclusive) who have been followed from 2000/2001 through 2010. The AAH-Heart study group is a subset of AAH participants recruited in 2009–11 to examine the inter-relationships between depression and CAD in this population. State-of-the-art CAD phenotyping is based on cardiovascular characterizations (coronary artery calcium, carotid intima-media thickness, cardiac structure and function, and autonomic function). Depression phenotyping is based on standardized questionnaires and detailed interviews. Single nucleotide polymorphisms of selected genes in inflammatory and serotonin-signaling pathways are being examined to provide information for investigating potential gene-depression interactions as modifiers of CAD traits. Information from the parent AAH study is being used to provide population-based prevalence estimates. Inflammatory and other biomarkers provide information about potential pathways. DISCUSSION: This population-based investigation will provide valuable information on the prevalence of both depression and CAD phenotypes in this population. The study will examine interactions between depression and genetic variants as modulators of CAD, with the intent of detecting mechanistic pathways linking these diseases to identify potential therapeutic targets. Analytic results will be reported as they become available

Embryonic vitamin D deficiency programs hematopoietic stem cells to induce type 2 diabetes

Environmental factors may alter the fetal genome to cause metabolic diseases. It is unknown whether embryonic immune cell programming impacts the risk of type 2 diabetes in later life. We demonstrate that transplantation of fetal hematopoietic stem cells (HSCs) made vitamin D deficient in utero induce diabetes in vitamin D-sufficient mice. Vitamin D deficiency epigenetically suppresses Jarid2 expression and activates the Mef2/PGC1a pathway in HSCs, which persists in recipient bone marrow, resulting in adipose macrophage infiltration. These macrophages secrete miR106-5p, which promotes adipose insulin resistance by repressing PIK3 catalytic and regulatory subunits and down-regulating AKT signaling. Vitamin D-deficient monocytes from human cord blood have comparable Jarid2/Mef2/PGC1a expression changes and secrete miR-106b-5p, causing adipocyte insulin resistance. These findings suggest that vitamin D deficiency during development has epigenetic consequences impacting the systemic metabolic milieu

Deletion of Macrophage Vitamin D Receptor Promotes Insulin Resistance and Monocyte Cholesterol Transport to Accelerate Atherosclerosis in Mice

Intense effort has been devoted to understanding predisposition to chronic systemic inflammation because it contributes to cardiometabolic disease. We demonstrate that deletion of the macrophage vitamin D receptor (VDR) in mice (KODMAC) is sufficient to induce insulin resistance by promoting M2 macrophage accumulation in the liver as well as increasing cytokine secretion and hepatic glucose production. Moreover, VDR deletion increases atherosclerosis by enabling lipid-laden M2 monocytes to adhere, migrate, and carry cholesterol into the atherosclerotic plaque and by increasing macrophage cholesterol uptake and esterification. Increased foam cell formation results from lack of VDR-SERCA2b interaction, causing SERCA dysfunction, activation of ER stress-CaMKII-JNKp-PPARγ signaling, and induction of the scavenger receptors CD36 and SR-A1. Bone marrow transplant of VDR-expressing cells into KODMAC mice improved insulin sensitivity, suppressed atherosclerosis, and decreased foam cell formation. The immunomodulatory effects of vitamin D in macrophages are thus critical in diet-induced insulin resistance and atherosclerosis in mice

Vitamin D Deficiency Induces High Blood Pressure and Accelerates Atherosclerosis in Mice

<div><p>Multiple epidemiological studies link vitamin D deficiency to increased cardiovascular disease (CVD), but causality and possible mechanisms underlying these associations are not established. To clarify the role of vitamin D-deficiency in CVD in vivo, we generated mouse models of diet-induced vitamin D deficiency in two backgrounds (LDL receptor- and ApoE-null mice) that resemble humans with diet-induced hypertension and atherosclerosis. Mice were fed vitamin D-deficient or -sufficient chow for 6 weeks and then switched to high fat (HF) vitamin D-deficient or –sufficient diet for 8–10 weeks. Mice with diet-induced vitamin D deficiency showed increased systolic and diastolic blood pressure, high plasma renin, and decreased urinary sodium excretion. Hypertension was reversed and renin was suppressed by returning chow-fed vitamin D-deficient mice to vitamin D-sufficient chow diet for 6 weeks. On a HF diet, vitamin D-deficient mice had ∼2-fold greater atherosclerosis in the aortic arch and ∼2–8-fold greater atherosclerosis in the thoracic and abdominal aorta compared to vitamin D-sufficient mice. In the aortic root, HF-fed vitamin D-deficient mice had increased macrophage infiltration with increased fat accumulation and endoplasmic reticulum (ER) stress activation, but a lower prevalence of the M1 macrophage phenotype within atherosclerotic plaques. Similarly, peritoneal macrophages from vitamin D-deficient mice displayed an M2-predominant phenotype with increased foam cell formation and ER stress. Treatment of vitamin D-deficient mice with the ER stress reliever PBA during HF feeding suppressed atherosclerosis, decreased peritoneal macrophage foam cell formation, and downregulated ER stress proteins without changing blood pressure. Thus, we suggest that vitamin D deficiency activates both the renin angiotensin system and macrophage ER stress to contribute to the development of hypertension and accelerated atherosclerosis, highlighting vitamin D replacement as a potential therapy to reduce blood pressure and atherosclerosis.</p> </div

Vitamin D deficiency promotes a pro-atherogenic M2 macrophage phenotype.

<p>Peritoneal macrophages from ApoE^−/− mice after vitamin D-sufficient or –deficient HFD were assessed by flow cytometry for (<b>A</b>) Cell surface markers for M1 and M2 phenotype (CCR7: gray, CD86: black, MR: dots, CD163: white) and (<b>B</b>) Macrophage phenotype ratio calculated from flow cytometry analysis to assess M1 vs. M2 predominance (vitamin D-sufficient: black, vitamin D-deficient: white). From the aortic root of vitamin D-sufficient (top) and -deficient (bottom) animals after 8 weeks on HFD, (<b>C</b>) Represenative image of double immunofluorescent staining for CCR7 (M1, green), MR (M2, green), and ADRP (red). Scale bar represents 50 µm. (<b>D</b>) Quantification of CCR7 immunofluorescent staining as a percentage of total atherosclerotic plaque area, (<b>E</b>) Co-localization (yellow) of CCR7 and MR with ADRP as a percentage of ADRP-positive area (n = 3 per group for all). Data expressed as mean ± SEM. *p<0.05, **p<0.01.</p

Blood pressure is reversibly increased in vitamin D deficient LDLR^−/− mice.

<p>Non-invasive systolic (SBP) and diastolic blood pressure (DBP) in LDLR^−/− mice on vitamin D-sufficient (black) or –deficient (white) diet (<b>A</b>) at baseline (n_suf = 12, n_def = 17), (<b>B</b>) after high fat diet (HFD) (n_suf = 13, n_def = 13), and (<b>C</b>) after 1 year on chow (n_suf = 10, n_def = 9). (<b>D</b>) Serum renin activity at baseline and after HFD (pooled samples of 10 animals per group). (<b>E</b>) Urinary sodium excretion at baseline and after HFD (baseline n_suf = 7, n_def = 5, HFD n_suf = 10, n_def = 13). (<b>F</b>) Blood pressure 6 weeks after returning vitamin D-deficient mice to a -sufficient diet (replacement: gray) (n_def = 7, n_replaced = 8). (<b>G</b>) Serum renin activity after returning vitamin D-deficient mice to a -sufficient diet (replacement: gray) (n_def = 3, n_replaced = 7). Data is expressed as mean ± SEM. *p<0.05, **p<0.01, ***p<0.0001.</p

Suppression of ER stress improves cholesterol handling and reduces atherosclerosis in vitamin D-deficient mice.

<p>ApoE^−/− mice were assessed after vitamin D-deficient HFD with and without PBA treatment. (<b>A</b>) Western blot for ER stress protein expression in peritoneal macrophages (n = 4 per group). (<b>B</b>) Quantification of atherosclerotic lesion area for control saline-treated (white circles) and PBA-treated (gray triangles) mice (n = 10 per group). (<b>C–D</b>) Macrophage total cholesterol and triglyceride content (n = 6 per group). (<b>E</b>) Macrophage phenotype ratio based on flow cytometry analysis of cell surface markers (n = 6 per group). (<b>F–G</b>) Dil-oxLDL cholesterol uptake (n = 4 per group) and HDL-stimulated cholesterol efflux (n = 6 per group). Vitamin D-deficient data is shown in white and PBA treatment in gray. Data expressed as mean ± SEM. *p<0.05, **p<0.01, ***p≤0.0001.</p

Vitamin D deficiency increases foam cell formation by altering macrophage lipid metabolism in ApoE^−/− mice.

<p>Peritoneal macrophages were harvested from ApoE^−/− mice after vitamin D –sufficient (black) or –deficient (white) HFD. (<b>A</b>) Representative Oil-Red-O stain. (<b>B–D</b>) Total cholesterol, free cholesterol, and triglyceride content (n = 3 per group). (<b>E–F</b>) Dil-oxLDL cholesterol uptake (n = 4 per group) and ApoAI-stimulated and HDL-stimulated cholesterol efflux (n = 4 per group). Data expressed as mean ± SEM. *p<0.05.</p