Monocytes fundamentally contribute to immune surveillance and the inflammatory response in immunoinflammatory diseases like atherosclerosis. Recruitment of these cells to the site of injury requires ...their trafficking across the blood vessel wall. A series of events, including capture, rolling, slow rolling, arrest, adhesion strengthening, and lateral locomotion, precede monocyte transmigration. Recent investigations have revealed new aspects of this cascade. This article revisits some conventional paradigms and selectively highlights new findings, including novel insights into monocyte differentiation and recently identified functional mediators, signalling pathways, and new structural aspects of monocyte extravasation. The emerging roles of endothelial junctional molecules like vascular endothelial-cadherin and the junctional adhesion molecule family, adhesion molecules such as intercellular adhesion molecule-1, molecules localized to the lateral border recycling compartment like cluster of differentiation 99, platelet/endothelial cell adhesion molecule-1, and poliovirus receptor (CD155), as well as other cell surface molecules such as cluster of differentiation 146 and ephrins in transendothelial migration are discussed.
Integrin-based therapeutics have garnered considerable interest in the medical treatment of inflammation. Integrins mediate the fast recruitment of monocytes and neutrophils to the site of ...inflammation, but are also required for host defense, limiting their therapeutic use. Here, we report a novel monoclonal antibody, anti-M7, that specifically blocks the interaction of the integrin Mac-1 with its pro-inflammatory ligand CD40L, while not interfering with alternative ligands. Anti-M7 selectively reduces leukocyte recruitment in vitro and in vivo. In contrast, conventional anti-Mac-1 therapy is not specific and blocks a broad repertoire of integrin functionality, inhibits phagocytosis, promotes apoptosis, and fuels a cytokine storm in vivo. Whereas conventional anti-integrin therapy potentiates bacterial sepsis, bacteremia, and mortality, a ligand-specific intervention with anti-M7 is protective. These findings deepen our understanding of ligand-specific integrin functions and open a path for a new field of ligand-targeted anti-integrin therapy to prevent inflammatory conditions.
Immune Mechanisms of Plaque Instability Gerhardt, Teresa; Haghikia, Arash; Stapmanns, Philip ...
Frontiers in cardiovascular medicine,
01/2022, Letnik:
8
Journal Article
Recenzirano
Odprti dostop
Inflammation crucially drives atherosclerosis from disease initiation to the emergence of clinical complications. Targeting pivotal inflammatory pathways without compromising the host defense could ...compliment therapy with lipid-lowering agents, anti-hypertensive treatment, and lifestyle interventions to address the substantial residual cardiovascular risk that remains beyond classical risk factor control. Detailed understanding of the intricate immune mechanisms that propel plaque instability and disruption is indispensable for the development of novel therapeutic concepts. In this review, we provide an overview on the role of key immune cells in plaque inception and progression, and discuss recently identified maladaptive immune phenomena that contribute to plaque destabilization, including epigenetically programmed trained immunity in myeloid cells, pathogenic conversion of autoreactive regulatory T-cells and expansion of altered leukocytes due to clonal hematopoiesis. From a more global perspective, the article discusses how systemic crises such as acute mental stress or infection abruptly raise plaque vulnerability and summarizes recent advances in understanding the increased cardiovascular risk associated with COVID-19 disease. Stepping outside the box, we highlight the role of gut dysbiosis in atherosclerosis progression and plaque vulnerability. The emerging differential role of the immune system in plaque rupture and plaque erosion as well as the limitations of animal models in studying plaque disruption are reviewed.
RATIONALE:CD4 T cells are involved in the pathogenesis of atherosclerosis, but atherosclerosis-specific CD4 T cells have not been described. Moreover, the chemokine(s) that regulates T-cell ...trafficking to the atherosclerotic lesions is also unknown.
OBJECTIVE:In Apoe mice with mature atherosclerotic lesions (5 months of high fat diet), we find that most aortic T cells express CCR5 and interferon-γ with a unique combination of cell surface markers (CD4CD25CD44CD62L) and transcription factors (FoxP3T-bet). We call these cells CCR5Teff. We investigated the role of CCR5 in regulating T-cell homing to the atherosclerotic aorta and the functionality of the CCR5Teff cells.
METHODS AND RESULTS:CCR5Teff cells are exclusively found in the aorta and para-aortic lymph nodes of Apoe mice. They do not suppress T-cell proliferation in vitro and are less potent than regulatory T cells at inhibiting cytokine secretion. Blocking or knocking out CCR5 or its ligand CCL5 significantly blocks T-cell homing to atherosclerotic aortas. Transcriptomic analysis shows that CCR5Teff cells are more similar to effector T cells than to regulatory T cells. They secrete interferon-γ, interleukin-2, interleukin-10, and tumor necrosis factor. Adoptive transfer of these CCR5Teff cells significantly increases atherosclerosis.
CONCLUSIONS:CCR5 is specifically needed for CD4 T-cell homing to the atherosclerotic plaques. CCR5CD4 T cells express an unusual combination of transcription factors, FoxP3 and T-bet. Although CCR5Teff express FoxP3, we showed that they are not regulatory and adoptive transfer of these cells exacerbates atherosclerosis.
Throughout the inflammatory response that accompanies atherosclerosis, autoreactive CD4
T-helper cells accumulate in the atherosclerotic plaque. Apolipoprotein B
(apoB), the core protein of ...low-density lipoprotein, is an autoantigen that drives the generation of pathogenic T-helper type 1 (T
1) cells with proinflammatory cytokine secretion. Clinical data suggest the existence of apoB-specific CD4
T cells with an atheroprotective, regulatory T cell (T
) phenotype in healthy individuals. Yet, the function of apoB-reactive T
and their relationship with pathogenic T
1 cells remain unknown.
To interrogate the function of autoreactive CD4
T cells in atherosclerosis, we used a novel tetramer of major histocompatibility complex II to track T cells reactive to the mouse self-peptide apo B
(apoB
) at the single-cell level.
We found that apoB
T cells build an oligoclonal population in lymph nodes of healthy mice that exhibit a T
-like transcriptome, although only 21% of all apoB
T cells expressed the T
transcription factor FoxP3 (Forkhead Box P3) protein as detected by flow cytometry. In single-cell RNA sequencing, apoB
T cells formed several clusters with mixed T
signatures that suggested overlapping multilineage phenotypes with pro- and anti-inflammatory transcripts of T
1, T helper cell type 2 (T
2), and T helper cell type 17 (T
17), and of follicular-helper T cells. ApoB
T cells were increased in mice and humans with atherosclerosis and progressively converted into pathogenic T
1/T
17-like cells with proinflammatory properties and only a residual T
transcriptome. Plaque T cells that expanded during progression of atherosclerosis consistently showed a mixed T
1/T
17 phenotype in single-cell RNA sequencing. In addition, we observed a loss of FoxP3 in a fraction of apoB
T
in lineage tracing of hyperlipidemic
mice. In adoptive transfer experiments, converting apoB
T
failed to protect from atherosclerosis.
Our results demonstrate an unexpected mixed phenotype of apoB-reactive autoimmune T cells in atherosclerosis and suggest an initially protective autoimmune response against apoB with a progressive derangement in clinical disease. These findings identify apoB autoreactive T
as a novel cellular target in atherosclerosis.
Although immunization with major histocompatibility complex (MHC) class II-restricted apolipoprotein B (ApoB) peptides has been shown to be atheroprotective, the mechanism is unclear. Here, we ...investigated CD4
T cell populations in immunized atherosclerotic mice. Peptides (16-mers) from mouse ApoB, the core protein of low-density lipoprotein (LDL), were screened for binding to I-A
by computer prediction and confirmed by radiolabeled peptide competition. Three new peptides, P101 (FGKQGFFPDSVNKALY, 5.5 nM IC
), P102 (TLYALSHAVNSYFDVD, 6.8 nM), and P103 (LYYKEDKTSLSASAAS, 95 nM), were tested in an atherosclerosis model (
mice on Western diet). Immunization with each of the three peptides (1 time in complete Freund's adjuvant subcuntaneously and 4 time in incomplete Freund's adjuvant intraperitoneally) but not with adjuvant alone showed significantly reduced atherosclerotic plaques in the aortic root by serial sections and in the whole aorta by en face staining. There were no differences in body weight, LDL cholesterol, or triglycerides. Peritoneal leukocytes from ApoB peptide-immunized mice, but not control mice, secreted significant amounts of IL-10 (150 pg/ml). Flow cytometry showed that peptide immunization induced IL-10 in 10% of peritoneal CD4
T cells, some of which also expressed chemokine (C-C motif) receptor 5 (CCR5). Vaccination with ApoB peptides expanded peritoneal FoxP3
regulatory CD4
T cells and more than tripled the number of CCR5
FoxP3
cells. Similar trends were also seen in the draining mediastinal lymph nodes but not in the nondraining inguinal lymph nodes. We conclude that vaccination with MHC class II-restricted autologous ApoB peptides induces regulatory T cells (Tregs) and IL-10, suggesting a plausible mechanism for atheroprotection.
Vaccination against apolipoprotein B (ApoB), the protein of LDL, attracts attention as a novel approach to prevent atherosclerosis. We discovered major histocompatibility complex class II-restricted ApoB peptides, which reduce atherosclerosis and induce IL-10-producing CD4
T cells and chemokine (C-C motif) receptor 5 expression on regulatory T cells, suggesting that immunization with ApoB peptides inhibits atherosclerosis by inducing anti-inflammatory cytokines.
Abstract
Background and aims
In one-third of patients with acute coronary syndrome (ACS), thrombosis occurs despite an intact fibrous cap (IFC) (IFC–ACS, ‘plaque erosion’). Recent studies emphasize ...neutrophils as the immediate inflammatory response in this pathology, but their exact molecular activation patterns are still poorly understood and may represent future therapeutic targets.
Methods and results
Thirty-two patients with IFC–ACS and matched patients with ACS with ruptured fibrous cap (RFC) (RFC–ACS) from the OPTICO–ACS study were included, and blood samples were collected from the local site of the culprit lesion and the systemic circulation. Neutrophil surface marker expression was quantified by flow cytometry. Neutrophil cytotoxicity towards endothelial cells was examined in an ex vivo co-culture assay. Secretion of active matrix metalloproteinase 9 (MMP9) by neutrophils was evaluated using zymography in supernatants and in plasma samples. Optical coherence tomography (OCT)–embedded thrombi were used for immunofluorescence analysis. Toll-like receptor 2 (TLR2) expression was higher on neutrophils from IFC–ACS than RFC–ACS patients. TLR2 stimulation increased the release of active MMP9 from local IFC–ACS–derived neutrophils, which also aggravated endothelial cell death independently of TLR2. Thrombi of IFC–ACS patients exhibited more hyaluronidase 2 with concomitant increase in local plasma levels of the TLR2 ligand: hyaluronic acid.
Conclusion
The current study provides first in-human evidence for distinct TLR2-mediated neutrophil activation in IFC–ACS, presumably triggered by elevated soluble hyaluronic acid. Together with disturbed flow conditions, neutrophil-released MMP9 might be promoting endothelial cell loss–triggered thrombosis and therefore providing a potential future target for a phenotype-specific secondary therapeutic approach in IFC–ACS.
Structured Graphical Abstract
Structured Graphical Abstract
TLR2, Toll-like receptor 2; HA, hyaluronic acid; MMP9, matrix metalloproteinase 9; HYAL2, hyaluronidase 2.
Abstract
Aims
Rupture of the fibrous cap (RFC) and erosion of an intact fibrous cap (IFC) are the two predominant mechanisms causing acute coronary syndromes (ACS). It is uncertain whether clinical ...outcomes are different following RFC-ACS vs. IFC-ACS and whether this is affected by a specific inflammatory response. The prospective, translational OPTIcal-COherence Tomography in Acute Coronary Syndrome study programme investigates the impact of the culprit lesion phenotype on inflammatory profiles and prognosis in ACS patients.
Methods and results
This analysis included 398 consecutive ACS patients, of which 62% had RFC-ACS and 25% had IFC-ACS. The primary endpoint was a composite of cardiac death, recurrent ACS, hospitalization for unstable angina, and target vessel revascularization at 2 years major adverse cardiovascular events (MACE+). Inflammatory profiling was performed at baseline and after 90 days. Patients with IFC-ACS had lower rates of MACE+ than those with RFC-ACS (14.3% vs. 26.7%, P = 0.02). In 368-plex proteomic analyses, patients with IFC-ACS showed lower inflammatory proteome expression compared with those with RFC-ACS, including interleukin-6 and proteins associated with the response to interleukin-1β. Circulating plasma levels of interleukin-1β decreased from baseline to 3 months following IFC-ACS (P < 0.001) but remained stable following RFC-ACS (P = 0.25). Interleukin-6 levels decreased in patients with RFC-ACS free of MACE+ (P = 0.01) but persisted high in those with MACE+.
Conclusion
This study demonstrates a distinct inflammatory response and a lower risk of MACE+ following IFC-ACS. These findings advance our understanding of inflammatory cascades associated with different mechanisms of plaque disruption and provide hypothesis generating data for personalized anti-inflammatory therapeutic allocation to ACS patients, a strategy that merits evaluation in future clinical trials.
Structured Graphical Abstract
Structured Graphical Abstract
ACS, acute coronary syndrome; IFC, intact fibrous cap; IL-6, interleukin-6; LDLC, low-density lipoprotein cholesterol; MACE+, major adverse cardiovascular events, MΦ, macrophage; RFC, ruptured fibrous cap; TCFA, thin-cap fibro-atheroma. ns, not significant; *P < 0.05.
Abstract
Background
Restrictive cardiomyopathy is rare and heterogeneous in origin, clinical manifestation, and prognosis. Familial forms have, amongst others, been associated with mutations in the ...TNNI3 gene. We present a case of familial restrictive cardiomyopathy associated with a novel TNNI3 mutation including longitudinal follow-up.
Case summary
A 27-year-old woman was evaluated for fatigue in the context of a family history of sudden cardiac death. Echocardiography was normal except for mild left atrial dilatation. Focused genetic screening, limited to the most common genes associated with cardiomyopathy, was unremarkable in 2006. In biopsy, mild inflammatory cardiomyopathy was diagnosed, and the patient was discharged. Thirteen years later, rapid clinical deterioration occurred in the context of new-onset atrial fibrillation (AF). Echocardiography now showed gross bi-atrial dilatation and evidence of diastolic dysfunction. Based on haemodynamic tracings during angiography, a diagnosis of restrictive cardiomyopathy was made. In 2018, next-generation sequencing revealed the hitherto undescribed Troponin I variant Lys193Glu in a functionally critical domain. Haemodynamic stabilization was achieved by pulmonary vein isolation. Until now, the patient remains symptom free under diuretic treatment.
Discussion
Diagnosis of restrictive cardiomyopathy is complicated by often oligosymptomatic early presentation and a diverse clinical picture. Thorough medical and family history and early invasive haemodynamic tracing are indispensable in diagnosis. Therapy-refractory AF should raise suspicion. Reporting of longitudinal follow-up cases is essential to better understand the early symptoms, development, and prognosis of this rare disease. Broad genetic testing in unclear cases has become more available and affordable and should be considered early in the diagnostic workflow.
Spotty calcium deposits (SCD) represent a vulnerable plaque feature which seems to result - as based on recent invitro studies - from inflammatory vessel-wall interactions. SCD can be reliably ...assessed by optical coherence tomography (OCT). Their prognostic impact is yet unknown. Therefore, the aims of this translational study were to comprehensively characterize different plaque calcification patterns, to analyze the associated inflammatory mechanisms in the microenvironment of acute coronary syndrome (ACS)-causing culprit lesions (CL) and to investigate the prognostic significance of SCD in a large cohort of ACS-patients.
CL of the first 155 consecutive ACS-patients from the translational OPTICO-ACS-study program were investigated by OCT-characterization of the calcium phenotype at ACS-causing culprit lesions. Simultaneous immunophenotyping by flow-cytometric analysis and cytokine bead array technique across the CL gradient (ratio local/systemic levels) was performed and incidental major adverse cardiovascular events plus (MACE+) at 12 months after ACS were assessed.
SCD were observed within 45.2% of all analyzed ACS-causing culprit lesions (CL). Culprits containing spotty calcium were characterized by an increased culprit ratio of innate effector cytokines interleukin (IL)-8 2.04 (1.24) vs. 1.37 (1.10) p < 0.05, as well as TNF (tumor necrosis factor)-α 1.17 (0.93) vs. 1.06 (0.89); p < 0.05) and an increased ratio of circulating neutrophils 0.96 (0.85) vs. 0.91 (0.77); p < 0.05 as compared to culprit plaques without SCD. Total monocyte levels did not differ between the two groups (p = n.s.). However, SCD-containing CLs were characterized by an increased culprit ratio of intermediate monocytes (1.15 (0.81) vs. 0.96 (0.84); p < 0.05) with an enhanced surface expression of the integrin receptor CD49d as compared to intermediate monocytes derived from SCD-free CLs (1.06 (0.94) vs. 0.97 (0.91) p < 0.05. Finally, 12 months rates of MACE+ were higher in patients with, as compared to patients without SCD at CL (16.4% vs. 5.3%; p < 0.05).
This study for the first time identified a specific inflammatory profile of CL with SCD, with a predominance of neutrophils, intermediate monocytes and their corresponding effector molecules. Hence, this study advances our understanding of ACS-causing CL and provides the basis for future personalized anti-inflammatory, therapeutic approaches to ACS.
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•Spotty calcium deposits (SCD) represent a feature of plaque vulnerability.•SCD are associated with a distinct, pro-inflammatory micro-environment at acute coronary syndrome (ACS)-causing culprit lesions.•SCD are associated with increased cardiovascular event rates at one-year follow up.•SCD may thereby facilitate secondary prevention and advance anti-inflammatory therapy after ACS.
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