scholarly journals Autoimmune Regulator (AIRE) Deficiency Does Not Affect Atherosclerosis and CD4 T Cell Immune Tolerance to Apolipoprotein B

2022 ◽  
Vol 8 ◽  
Author(s):  
Felix Sebastian Nettersheim ◽  
Simon Braumann ◽  
Kouji Kobiyama ◽  
Marco Orecchioni ◽  
Melanie Vassallo ◽  
...  
Keyword(s):  
T Cells ◽  
Immune Tolerance ◽  
Low Density Lipoprotein ◽  
Adaptive Immune Response ◽  
Density Lipoprotein ◽  
Chow Diet ◽  
Structural Protein ◽  
Autoimmune Regulator ◽  
And Gender ◽  
Underlying Mechanisms

Atherosclerosis is a chronic, lipid-driven disease of medium sized arteries which causes myocardial infarction and stroke. Recently, an adaptive immune response against the plaque-associated autoantigen Apolipoprotein B100 (ApoB), the structural protein component of low-density lipoprotein, has been implicated in atherogenesis. In healthy individuals, CD4+ T cells responding to ApoB mainly comprised regulatory T cells, which confer immune tolerance and atheroprotection. Mice and patients with atherosclerosis harbor increased numbers of proatherogenic ApoB-reactive T-helper cell subsets. Given the lack of therapies targeting proatherogenic immunity, clarification of the underlying mechanisms is of high clinical relevance. T cells develop in the thymus, where strong autoreactive T cells are eliminated in the process of negative selection. Herein, we investigated whether the transcription factor autoimmune regulator (AIRE), which controls expression of numerous tissue-restricted self-antigens in the thymus, is involved in mediating tolerance to ApoB and whether Aire deficiency might contribute to atherogenesis. Mice deficient for Aire were crossbred to apolipoprotein E-deficient mice to obtain atherosclerosis-prone Aire−/−Apoe−/− mice, which were fed a regular chow diet (CD) or western-type diet (WD). CD4+ T cells responding to the ApoB peptide p6 were analyzed by flow cytometry. We demonstrate that Aire deficiency influences neither generation nor activation of ApoB-reactive T cells and has only minor and overall inconsistent impacts on their phenotype. Furthermore, we show that atherosclerotic plaque size is not affected in Aire−/−Apoe−/− compared to Aire+/+Apoe−/−, irrespective of diet and gender. In conclusion, our data suggests that AIRE is not involved in regulating thymic expression of ApoB or atherosclerosis. Alternative mechanisms how ApoB-reactive CD4 T cells are selected in the thymus will have to be investigated.

Abstract 21: A Natural Repertoire of T Cells Recognizing ApoB-100 is Generated Early in Life and is Progressively Depleted During Atherosclerotic Disease

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Dennis Wolf ◽  
Teresa Gerhardt ◽  
Jacqueline Miller ◽  
Sara McArdle ◽  
Takayuki Kimura ◽  
...  
Keyword(s):  
T Cells ◽  
Lymph Nodes ◽  
Mhc Class Ii ◽  
T Regulatory Cells ◽  
Low Density Lipoprotein ◽  
Large Body ◽  
Density Lipoprotein ◽  
Western Diet ◽  
Chow Diet ◽  
Progressive Loss

Background: A large body of evidence implicates a role for T cell driven auto-immunity in atherosclerosis. T cells in the atherosclerotic plaque specifically respond to auto-antigens, including ApoB-100, the main protein in low-density lipoprotein (LDL). However, existence, function, and location of auto-reactive T cells in mice have not been demonstrated. Methods and Results: We have previously identified several peptides derived from mouse ApoB-100 that bind with high affinity to the I-A b MHC class II molecule of C57BL/6 mice. Immunization with these peptides conferred atheroprotection. We designed a novel fluorochrome-labeled P6:I-A b multimer to detect T cells specifically recognizing this complex by flow cytometry. Surprisingly, we detected small numbers of P6:I-A b+ CD4 + T cells in young C57Bl/6 mice that reside in peripheral lymph nodes, indicating the existence of a small natural repertoire of P6:I-A b auto-reactive T cells. This repertoire of T cells was increased in atherosclerosis-prone A poe -/- and Ldlr -/- mice and showed signs of previous antigen-exposure in 4 week old animals. T cells recognizing P6:I-A b were undetectable directly after birth, but expanded rapidly within the first 28 days in lymph nodes. The majority of P6:I-A b+ T cells expressed the defining transcription factors of T H 1, T-bet, T H 17, ROR-gamma T, or of T-regulatory cells, FoxP3. Feeding of Apoe -/- mice with a western diet induced a further skew towards the T H 1 and T H 17 lineage, but also resulted in a progressive loss of antigen-specific cells over time. In Apoe -/- mice fed with a western diet for 1 year, but not in Apoe -/- mice fed with a standard chow diet, auto-reactive T cells disappeared. Mechanistically, we found enhanced expression of exhaustion markers like ICOS-1 or PD-1 in antigen-specific T cells likely due to persisting antigen-exposure in this model. Conclusion: Our findings indicate that T cells specifically recognizing a peptide derived from ApoB-100 do not expand during the natural course of disease, but instead exist in atherosclerosis-prone animals in early life. Chronic exposure to antigen induces a progressive loss of auto-reactive T cells.

scholarly journals Age- and Gender-Related Differences in LDL-Cholesterol Management in Outpatients with Type 2 Diabetes Mellitus

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Giuseppina Russo ◽  
Basilio Pintaudi ◽  
Carlo Giorda ◽  
Giuseppe Lucisano ◽  
Antonio Nicolucci ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Serum Levels ◽  
Diabetes Duration ◽  
Lipid Lowering ◽  
Age And Gender ◽  
Chd Risk ◽  
And Gender

Background. Dyslipidemia contribute to the excess of coronary heart disease (CHD) risk observed in women with type 2 diabetes (T2DM). Low density lipoprotein-cholesterol (LDL-C) is the major target for CHD prevention, and T2DM women seem to reach LDL-C targets less frequently than men.Aim. To explore age- and gender-related differences in LDL-C management in a large sample of outpatients with T2DM.Results. Overall, 415.294 patients (45.3% women) from 236 diabetes centers in Italy were included. Women were older and more obese, with longer diabetes duration, higher total-cholesterol, LDL-C, and HDL-C serum levels compared to men (P<0.0001). Lipid profile was monitored in ~75% of subjects, women being monitored less frequently than men, irrespective of age. More women did not reach the LDL-C target as compared to men, particularly in the subgroup treated with lipid-lowering medications. The between-genders gap in reaching LDL-C targets increased with age and diabetes duration, favouring men in all groups.Conclusions. LDL-C management is worst in women with T2DM, who are monitored and reach targets less frequently than T2DM men. Similarly to men, they do not receive medications despite high LDL-C. These gender discrepancies increase with age and diabetes duration, exposing older women to higher CHD risk.

scholarly journals Platelet CD36 signaling through ERK5 promotes caspase-dependent procoagulant activity and fibrin deposition in vivo

2018 ◽  
Vol 2 (21) ◽  
pp. 2848-2861 ◽  
Author(s):  
Moua Yang ◽  
Andaleb Kholmukhamedov ◽  
Marie L. Schulte ◽  
Brian C. Cooley ◽  
Na’il O. Scoggins ◽  
...  
Keyword(s):  
Platelet Reactivity ◽  
Low Density Lipoprotein ◽  
Scavenger Receptor ◽  
Density Lipoprotein ◽  
Signaling Molecules ◽  
Chow Diet ◽  
Glycoprotein Vi ◽  
Platelet Signaling ◽  
Clinically Significant

Abstract Dyslipidemia is a risk factor for clinically significant thrombotic events. In this condition, scavenger receptor CD36 potentiates platelet reactivity through recognition of circulating oxidized lipids. CD36 promotes thrombosis by activating redox-sensitive signaling molecules, such as the MAPK extracellular signal-regulated kinase 5 (ERK5). However, the events downstream of platelet ERK5 are not clear. In this study, we report that oxidized low-density lipoprotein (oxLDL) promotes exposure of procoagulant phosphatidylserine (PSer) on platelet surfaces. Studies using pharmacologic inhibitors indicate that oxLDL-CD36 interaction–induced PSer exposure requires apoptotic caspases in addition to the downstream CD36-signaling molecules Src kinases, hydrogen peroxide, and ERK5. Caspases promote PSer exposure and, subsequently, recruitment of the prothrombinase complex, resulting in the generation of fibrin from the activation of thrombin. Caspase activity was observed when platelets were stimulated with oxLDL. This was prevented by inhibiting CD36 and ERK5. Furthermore, oxLDL potentiates convulxin/glycoprotein VI–mediated fibrin formation by platelets, which was prevented when CD36, ERK5, and caspases were inhibited. Using 2 in vivo arterial thrombosis models in apoE-null hyperlipidemic mice demonstrated enhanced arterial fibrin accumulation upon vessel injury. Importantly, absence of ERK5 in platelets or mice lacking CD36 displayed decreased fibrin accumulation in high-fat diet–fed conditions comparable to that seen in chow diet–fed animals. These findings suggest that platelet signaling through CD36 and ERK5 induces a procoagulant phenotype in the hyperlipidemic environment by enhancing caspase-mediated PSer exposure.

Abstract 44: Failure of Protective Autoimmunity in Mouse and Human Atherosclerosis

2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
Dennis Wolf ◽  
Teresa Gerhardt ◽  
Nathaly Anto Michel ◽  
Bjarke Hansen ◽  
Alessandro Sette ◽  
...  
Keyword(s):  
T Cells ◽  
Lymph Nodes ◽  
Mhc Class Ii ◽  
T Regulatory Cells ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
T Cell Response ◽  
Regulatory Cells ◽  
Protective Autoimmunity

Background: In atherosclerosis, CD4 + T helper cells recognize auto-antigens including ApoB, the main protein in low-density lipoprotein (LDL). However, atherosclerosis-specific, auto-reactive CD4 + T cells have not been detected in vivo , and their function is unknown. Methods and Results: We have previously identified peptides derived from mouse ApoB that bind with high affinity to the MHC class II molecule of C57BL/6 mice (I-A b ). We designed and validated a new multimer of a recombinant MHC-II molecule fused to one ApoB auto-epitopes, P6 (TGAYSNASSTESASY, P6:I-A b ), that enabled detection of low-affinity, P6-reactive CD4 + T cells. Using this P6:I-A b multimer, we identified ApoB-reactive CD4 + T cells in healthy, young C57BL/6 mice that were predominately differentiated T-regulatory cells (T regs ) and expressed IL-10, a known atheroprotective cytokine. This population was detectable in lymph nodes and already showed a memory phenotype in young animals without atherosclerosis. In Apoe -/- mice, adoptively transferred ApoB P6-specific T regs accumulated in the aorta and draining lymph nodes and gave rise to pathogenic T H 1 and T H 17 cells. This phenotypic switch was caused by enhanced plasticity of antigen-specific T regs as evidenced by multiple clusters of intermediate T reg -T eff phenotypes in single cell RNA sequencing of 4485 antigen-specific CD4 + T cells. In the plaque, many T cells were ex-T regs as identified by a FoxP3 lineage tracker mouse, suggesting that atherosclerosis-specific CD4 + T cells lost their regulatory capacity. Vaccination with P6 maintained a protective phenotype in antigen-specific T regs and protected from atherosclerosis. In humans, ApoB-specific CD4 + T cells from atherosclerotic patients showed the same cytokine patterns found in mouse CD4 + T cells, suggesting that autoimmunity to ApoB is protective first, but later gives rise to a pathogenic CD4 + T cell response that aggravates atherosclerosis. Conclusion: Protective T-regulatory cells recognizing peptide antigens of ApoB exist in naïve mice, protect against atherosclerosis, but convert into pathogenic T H 1 and -17 cells during the natural course of disease in mice and humans. These results call for immunomodulatory therapies to maintain protective autoimmunity.

scholarly journals Oxidized low-density lipoproteins induce tissue factor expression in T-lymphocytes via activation of lectin-like oxidized low-density lipoprotein receptor-1

2019 ◽  
Vol 116 (6) ◽  
pp. 1125-1135 ◽  
Author(s):  
Giovanni Cimmino ◽  
Plinio Cirillo ◽  
Stefano Conte ◽  
Grazia Pellegrino ◽  
Giusi Barra ◽  
...  
Keyword(s):  
T Cells ◽  
T Lymphocytes ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Ros Generation ◽  
Low Density ◽  
Dependent Manner ◽  
Cd8 Cells ◽  
Human Carotid

Abstract Aims T-lymphocytes plays an important role in the pathophysiology of acute coronary syndromes. T-cell activation in vitro by pro-inflammatory cytokines may lead to functional tissue factor (TF) expression, indicating a possible contribution of immunity to thrombosis. Oxidized low-density lipoproteins (oxLDLs) are found abundantly in atherosclerotic plaques. We aimed at evaluating the effects of oxLDLs on TF expression in T cells and the role of the lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1). Methods and results CD3+ cells were isolated from healthy volunteers. Gene, protein, and surface expression of TF, as well as of LOX-1, were assessed at different time-points after oxLDL stimulation. To determine whether oxLDL-induced TF was LOX-1 dependent, T cells were pre-incubated with an LOX-1 inhibiting peptide (L-RBP) or with an anti-LOX-1 blocking antibody. To exclude that TF expression was mediated by reactive oxygen species (ROS) generation, oxLDL-stimulated T cells were pre-incubated with superoxide dismutase + catalase or with 4-Hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (Tempol), an intracellular free radical scavenger. Finally, to determine if the observed findings in vitro may have a biological relevance, the presence of CD3+/TF+/LOX-1+ cells was evaluated by immunofluorescence in human carotid atherosclerotic lesions. oxLDLs induced functionally active TF expression in T cells in a dose- and time-dependent manner, independently on ROS generation. No effect was observed in native LDL-treated T cells. LOX-1 expression was also induced by oxLDLs in a time- and dose-dependent manner. Pre-incubation with L-RBP or anti-LOX-1 antibody almost completely inhibited oxLDL-mediated TF expression. Interestingly, human carotid plaques showed significant infiltration of CD3+ cells (mainly CD8+ cells), some of which were positive for both TF and LOX-1. Conclusion oxLDLs induce functional TF expression in T-lymphocytes in vitro via interaction of oxLDLs with LOX-1. Human carotid atherosclerotic plaques contain CD3+/CD8+cells that express both TF and LOX-1, indicating that also in patients these mechanisms may play an important role.

scholarly journals Adaptive Immune Responses in Human Atherosclerosis

2020 ◽  
Vol 21 (23) ◽  
pp. 9322
Author(s):  
Silvia Lee ◽  
Benjamin Bartlett ◽  
Girish Dwivedi
Keyword(s):  
T Cells ◽  
Low Density Lipoprotein ◽  
Clinical Manifestations ◽  
Density Lipoprotein ◽  
Chronic Inflammatory Disease ◽  
Th2 Cells ◽  
Low Density ◽  
Heat Shock Protein 60 ◽  
Atherosclerosis Progression ◽  
Human Atherosclerosis

Atherosclerosis is a chronic inflammatory disease that is initiated by the deposition and accumulation of low-density lipoproteins in the artery wall. In this review, we will discuss the role of T- and B-cells in human plaques at different stages of atherosclerosis and the utility of profiling circulating immune cells to monitor atherosclerosis progression. Evidence supports a proatherogenic role for intraplaque T helper type 1 (Th1) cells, CD4+CD28null T-cells, and natural killer T-cells, whereas Th2 cells and regulatory T-cells (Treg) have an atheroprotective role. Several studies indicate that intraplaque T-cells are activated upon recognition of endogenous antigens including heat shock protein 60 and oxidized low-density lipoprotein, but antigens derived from pathogens can also trigger T-cell proliferation and cytokine production. Future studies are needed to assess whether circulating cellular biomarkers can improve identification of vulnerable lesions so that effective intervention can be implemented before clinical manifestations are apparent.

Biphasic adaptative responses in VLDL metabolism and lipoprotein homeostasis during Gram-negative endotoxemia

2010 ◽  
Vol 18 (1) ◽  
pp. 89-99 ◽  
Author(s):  
Nerea Bartolomé ◽  
Patricia Aspichueta ◽  
María J Martínez ◽  
Mercedes Vázquez-Chantada ◽  
María L Martínez-Chantar ◽  
...  
Keyword(s):  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Transcript Abundance ◽  
Second Phase ◽  
Gene Transcript ◽  
Endotoxin Challenge ◽  
Lipoprotein Subclasses ◽  
Apob Mrna ◽  
Underlying Mechanisms ◽  
Vldl Assembly

Dyslipidemia and hepatic overproduction of very low density lipoprotein (VLDL) are hallmarks of the septic response, yet the underlying mechanisms are not fully defined. We evaluated the lipoprotein subclasses profile and hepatic VLDL assembly machinery over 24 h in fasted LPS-treated rats. The response of serum non-esterified fatty acids (NEFA) and glucose to endotoxin was biphasic, with increased levels of NEFA and hypoglycemia in the first 12 h-phase, and low NEFA and high glucose in the second 12 h-phase. Hypertriglyceridemia was more marked in the first 12 h (6.8-fold), when triglyceride abundance increased in all lipoprotein subclasses, and preferentially in large VLDL. The abundance of medium-sized VLDL and the increase in the number of VLDL particles was higher in the second phase (10-fold vs 5-fold in the first phase); however, apoB gene transcript abundance increased only in the second phase. Analysis of putative pre-translational mechanisms revealed that neither increased Apob transcription rate nor increased transcript binding to mRNA stabilizing HuR (Hu antigen R) protein paralleled the increase in apoB transcripts. In conclusion, endotoxin challenge induces increases in plasma NEFA and large, triglyceride-rich VLDL. After approximately 12 h, the triglyceride-rich VLDLs are replaced by medium-sized, triglyceride-poor VLDL particles. Hepatic apoB mRNA abundance also increases during the second period, suggesting a role for apoB protein expression in the acute reaction against sepsis.

Effect of aging and obesity on the expression of dyslipidaemia in children from families with familial combined hyperlipidaemia

2006 ◽  
Vol 112 (2) ◽  
pp. 131-139 ◽  
Author(s):  
Ewoud ter Avest ◽  
Allan D. Sniderman ◽  
Sebastian J. H. Bredie ◽  
Albert Wiegman ◽  
Anton F. H. Stalenhoef ◽  
...  
Keyword(s):  
Plasma Lipids ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Indirect Evidence ◽  
Low Density ◽  
Tissue Mass ◽  
Adipose Tissue Mass ◽  
And Gender ◽  
Genetically Determined

The aim of the present study was to delineate the mechanism(s) responsible for the increased secretion of VLDL (very-low-density lipoprotein) particles in patients with FCH (familial combined hyperlipidaemia). In 194 young adults (<25 years of age) recruited from families with FCH, we investigated how plasma lipids, (apo)lipoproteins and BMI (body mass index) varied with age. Furthermore, we performed a 5-year follow-up study of clinical and biochemical characteristics of a subset of this population (n=85) stratified by apoB (apolipoprotein B) levels (below or above the 75th percentile adjusted for age and gender). Plasma apoB concentration (r=0.45, P<0.0001), triacylglycerol (triglyceride) concentration (r=0.45, P<0.0001), LDL (low-density lipoprotein) subfraction profile (r=−0.46, P<0.0001) and BMI (r=0.51, P<0.0001) were significantly associated with age. Plasma apoB concentration in the hyperapoB group was already elevated at a young age, whereas other characteristics of FCH, as observed in adults, including triacylglycerol levels >1.5 mmol/l and/or small-dense LDL, were observed only sporadically. After the 5-year follow-up, BMI increased in both groups, and this increase was associated with changes in apoB (r=0.27, P<0.05), triacylglycerol (r=0.30, P<0.01), VLDL cholesterol (r=0.22, P<0.05), VLDL triacylglycerol (r=0.25, P<0.05) and high-density lipoprotein cholesterol (r=−0.27, P<0.05). In conclusion, we have found indirect evidence of a primary, presumably genetically determined, increase in plasma apoB concentration occurring early in life of offspring from families with FCH. However, aging-related post-maturation increases in adipose tissue mass also appear to contribute to an aggravation and/or modulation of this genetically determined apoB overproduction.

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