Frequency of monocyte subsets is linked to the severity of atherosclerosis in patients with ischemic heart disease: A case-control study

Role of monocytes and dendritic cells in cardiac reverse remodelling after cardiac resynchronization therapy

BACKGROUND AND AIMS

Monocytes and dendritic cells (DC) are both key inflammatory cells, with recognized effects on cardiac repair. However, there are distinct subsets of monocytes with potential for beneficial or detrimental effects on heart failure (HF) pathogenesis. The connection between reverse cardiac remodelling, the potential anti-inflammatory effect of cardiac resynchronization therapy (CRT) and monocytes and DC homeostasis in HF is far from being understood. We hypothesized that monocytes and DC play an important role in cardiac reverse remodelling and CRT response. Therefore, we aimed to assess the potential role of baseline peripheral levels of blood monocytes and DC subsets and their phenotypic and functional activity for CRT response, in HF patients. As a secondary objective, we aimed to evaluate the impact of CRT on peripheral blood monocytes and DC subsets, by comparing baseline and post CRT circulating levels and phenotypic and functional activity.

METHODS

Forty-one patients with advanced HF scheduled for CRT were included in this study. The quantification and phenotypic determination of classical (cMo), intermediate (iMo) and non-classical monocytes (ncMo), as well as of myeloid (mDC) and plasmacytoid DC (pDC) were performed by flow cytometry in a FACSCanto™II (BD) flow cytometer. The functional characterization of total monocytes and mDC was performed by flow cytometry in a FACSCalibur flow cytometer, after in vitro stimulation with lipopolysaccharide from Escherichia coli plus interferon (IFN)-γ, in the presence of Brefeldina A. Comparisons between the control and the patient group, and between responders and non-responders to CRT were performed.

RESULTS

Compared to the control group, HF population presented a significantly lower frequency of pDC at baseline and a higher proportion of monocytes and mDC producing IL-6 and IL-1β, both before and 6-months after CRT (T6). There was a remarkable decrease of cMo and an increase of iMo after CRT, only in responders. The responder group also presented higher ncMo values at T6 compared to the non-responder group. Both responders and non-responders presented a decrease in the expression of CD86 in all monocyte and DC populations after CRT. Moreover, in non-responders, the increased frequency of IL-6-producing DC persisted after CRT.

CONCLUSION

Our study provides new knowledge about the possible contribution of pDC and monocytes subsets to cardiac reverse remodelling and response to CRT. Additionally, CRT is associated with a reduction on CD86 expression by monocytes and DC subsets and in their potential to produce pro-inflammatory cytokines, contributing, at least in part, for the well described anti-inflammatory effects of CRT in HF patients.

Immediate-release niacin and a monounsaturated fatty acid-rich meal on postprandial inflammation and monocyte characteristics in men with metabolic syndrome

BACKGROUND & AIM

When considered separately, long-term immediate-release niacin and fatty meals enriched in monounsaturated fatty acids (MUFA) decrease postprandial triglycerides, but their effects on postprandial inflammation, which is common in individuals with metabolic syndrome, are less known. Moreover, successful combination is lacking and its impact on acute disorders of the innate immune cells in the metabolic syndrome remains unclear. Here, we aimed to establish the effects from combination with niacin of different fats [butter, enriched in saturated fatty acids (SFA), olive oil, enriched in MUFA, and olive oil supplemented with eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids] on plasma inflammatory markers and circulating monocyte subsets, activation and priming at the postprandial period in individuals with metabolic syndrome.

METHODS

A random-order within-subject crossover experiment was performed, in which 16 individuals with metabolic syndrome and 16 age-matched healthy volunteers took 2 g immediate-release niacin together with the corresponding fatty meal or a meal with no fat as control. In total, 128 postprandial curves were analysed. We sampled hourly over 6 h for plasma concentrations of soluble inflammatory markers and triglycerides. Circulating monocyte subsets (CD14/CD16 balance), activation (CCL2/CCR2 axis) and priming (M1/M2-like phenotype) at the time of postprandial hypertriglyceridemic peak were also addressed.

RESULTS

Dietary SFA (combined with niacin) promote postprandial excursions of circulating IL-6, IL-1β, TNF-α and CD14/CCR2-rich monocytes with a pro-inflammatory M1-like phenotype, particularly in individuals with metabolic syndrome. In contrast, dietary MUFA (combined with niacin) postprandially increased circulating CD16-rich monocytes with an anti-inflammatory M2-like phenotype. Omega-3 PUFA did not add to the effects of MUFA.

CONCLUSION

The co-administration of a single-dose of immediate-release niacin with a fatty meal rich in MUFA, in contrast to SFA, suppresses postprandial inflammation at the levels of both secretory profile and monocyte response in individuals with metabolic syndrome. These findings highlight a potential role of combining niacin and dietary MUFA for the homeostatic control of inflammation and the innate immune system, identifying a new search direction for the management of disorders associated with the metabolic syndrome.

Non-classical monocytes frequency and serum vitamin D3 levels are linked to diabetic foot ulcer associated with peripheral artery disease

AIMS/INTRODUCTION

Peripheral artery disease (PAD) serves as a risk factor for diabetic foot ulcers (DFUs). PAD pathology involves atherosclerosis and impaired immunity. Non-classical monocytes are believed to have an anti-inflammatory role. 1,25-Dihydroxy vitamin D (vitamin D3 ) is claimed to have immune-modulating and lipid-regulating roles. Vitamin D receptor is expressed on monocytes. We aimed to investigate if circulating non-classical monocytes and vitamin D3 were implicated in DFUs associated with PAD.

MATERIALS AND METHODS

There were two groups of DFU patients: group 1 (n = 40) included patients with first-degree DFUs not associated with PAD, and group 2 (n = 50) included patients with DFU with PAD. The monocyte phenotypes were detected using flow cytometry. Vitamin D3 was assessed by enzyme-linked immunosorbent assay.

RESULTS

DFU patients with PAD showed a significant reduction in the frequency of non-classical monocytes and vitamin D3 levels, when compared with DFU patients without PAD. The percentage of non-classical monocytes positively correlated with vitamin D3 level (r = 0.4, P < 0.01) and high-density lipoprotein (r = 0.5, P < 0.001), whereas it was negatively correlated with cholesterol (r = -0.5, P < 0.001). Vitamin D3 was negatively correlated with triglyceride/high-density lipoprotein (r = -0.4, P < 0.01). Regression analysis showed that a high vitamin D3 serum level was a protective factor against PAD occurrence.

CONCLUSIONS

Non-classical monocytes frequency and vitamin D3 levels were significantly reduced in DFU patients with PAD. Non-classical monocytes frequency was associated with vitamin D3 in DFUs patients, and both parameters were linked to lipid profile. Vitamin D3 upregulation was a risk-reducing factor for PAD occurrence.

The role of monocytes in thrombotic diseases: a review

Cardiovascular and cerebrovascular diseases are the number one killer threatening people's life and health, among which cardiovascular thrombotic events are the most common. As the cause of particularly serious cardiovascular events, thrombosis can trigger fatal crises such as acute coronary syndrome (myocardial infarction and unstable angina), cerebral infarction and so on. Circulating monocytes are an important part of innate immunity. Their main physiological functions are phagocytosis, removal of injured and senescent cells and their debris, and development into macrophages and dendritic cells. At the same time, they also participate in the pathophysiological processes of pro-coagulation and anticoagulation. According to recent studies, monocytes have been found to play a significant role in thrombosis and thrombotic diseases of the immune system. In this manuscript, we review the relationship between monocyte subsets and cardiovascular thrombotic events and analyze the role of monocytes in arterial thrombosis and their involvement in intravenous thrombolysis. Finally, we summarize the mechanism and therapeutic regimen of monocyte and thrombosis in hypertension, antiphospholipid syndrome, atherosclerosis, rheumatic heart disease, lower extremity deep venous thrombosis, and diabetic nephropathy.

Insulin-like growth factor 1 reduces coronary atherosclerosis in pigs with familial hypercholesterolemia

Although murine models of coronary atherosclerotic disease have been used extensively to determine mechanisms, limited new therapeutic options have emerged. Pigs with familial hypercholesterolemia (FH pigs) develop complex coronary atheromas that are almost identical to human lesions. We reported previously that insulin-like growth factor 1 (IGF-1) reduced aortic atherosclerosis and promoted features of stable plaque in a murine model. We administered human recombinant IGF-1 or saline (control) in atherosclerotic FH pigs for 6 months. IGF-1 decreased relative coronary atheroma in vivo (intravascular ultrasound) and reduced lesion cross-sectional area (postmortem histology). IGF-1 increased plaque's fibrous cap thickness, and reduced necrotic core, macrophage content, and cell apoptosis, consistent with promotion of a stable plaque phenotype. IGF-1 reduced circulating triglycerides, markers of systemic oxidative stress, and CXCL12 chemokine levels. We used spatial transcriptomics (ST) to identify global transcriptome changes in advanced plaque compartments and to obtain mechanistic insights into IGF-1 effects. ST analysis showed that IGF-1 suppressed FOS/FOSB factors and gene expression of MMP9 and CXCL14 in plaque macrophages, suggesting possible involvement of these molecules in IGF-1's effect on atherosclerosis. Thus, IGF-1 reduced coronary plaque burden and promoted features of stable plaque in a pig model, providing support for consideration of clinical trials.

Low sCD163/TWEAK Ratio at First Day After Acute Myocardial Infarction Associated with Adverse Cardiac Remodeling in Non-Elderly Patients

Aim    In this study, we aimed to investigate the role of sCD163 / tumor necrosis factor-like weak apoptosis-inducing (TWEAK) ratio in cardiac remodeling in non-elderly patients diagnosed with first acute myocardial infarction (MI).Material and Methods    Forty-four patients (age ranges: 40–64 years) diagnosed with first-time acute ST-elevation MI in the emergency department were evaluated with cardiac magnetic resonance (CMR) imaging. Adverse remodeling (AR) was defined the increases of left ventricular end-diastolic volume by ≥12 % by CMR at 6‑month post-MI TWEAK and sCD163 were measured at the first day (baseline), 2 weeks and 6 weeks post-MI.Results    The average age of patients included in the study was 53.6±5.1 years. AR was detected in 18 patients at the 6 months post-MI. At the first day post-MI, median sCD163 concentration (116 069 vs 86 394 pg / mL, p=0.040) and median TWEAK concentration (759.4 vs 220.1 pg / mL, p<0.001) were higher in AR group compared to group without AR (the non-AR group), median sCD163 / TWEAK ratio (101.4 vs. 406.8; p<0.001) was lower. At the first day post-MI, concentrations of TWEAK and sCD163 showed a positive correlation in AR group and group without AR s. At 2 weeks post-MI, positive correlation continued in the non-AR group, but no significant correlation was found in the AR group. At the first day post-MI, sCD163 / TWEAK ratio was higher diagnostic performance compared to TWEAK and sCD163.Conclusion    In the early phase post-MI, the relationship between sCD163 – TWEAK may have an important role in AR pathogenesis. A lower sCD163 / TWEAK ratio on the first day after MI was associated with an increase in left ventricular end-diastolic volume after 6 months of follow-up.

The Potential Role of Electronegative High-Density Lipoprotein H5 Subfraction in RA-Related Atherosclerosis

Although the heterogeneity of high-density lipoprotein-cholesterol (HDL-c) composition is associated with atherosclerotic cardiovascular risk, the link between electronegative subfractions of HDL-c and atherosclerosis in rheumatoid arthritis (RA) remains unknown. We examined the association of the percentage of the most electronegative subfraction of HDL-c (H5%) and RA-related atherosclerosis. Using anion-exchange purification/fast-protein liquid chromatography, we demonstrated significantly higher H5% in patients (median, 7.2%) than HC (2.8%, p < 0.005). Multivariable regression analysis revealed H5% as a significant predictor for subclinical atherosclerosis. We subsequently explored atherogenic role of H5 using cell-based assay. The results showed significantly higher levels of IL-1β and IL-8 mRNA in H5-treated (mean ± SD, 4.45 ± 1.22 folds, 6.02 ± 1.43-folds, respectively) than H1-treated monocytes (0.89 ± 0.18-folds, 1.03 ± 0.26-folds, respectively, both p < 0.001). In macrophages, H5 upregulated the mRNA and protein expression of IL-1β and IL-8 in a dose-dependent manner, and their expression levels were significantly higher than H1-treated macrophages (all p < 0.001). H5 induced more foam cell formation compared with H1-treated macrophages (p < 0.005). In addition, H5 has significantly lower cholesterol efflux capacity than H1 (p < 0.005). The results of nanoLC-MS/MS approach reveal that the best discriminator between high-H5% and normal-H5% is Apo(a), the main constituent of Lp(a). Moreover, Lp(a) level is a significant predictor for high-H5%. These observations suggest that H5 is involved in RA-related atherosclerosis.

Cells of the Immune System in Cardiac Remodeling: Main Players in Resolution of Inflammation and Repair After Myocardial Infarction

The burden of heart failure (HF), developing after myocardial infarction MI, still represents a major issue in clinical practice. Failure of appropriate resolution of inflammation during post-myocardial injury is associated with unsuccessful left ventricular remodeling and underlies HF pathogenesis. Cells of the immune system have been shown to mediate both protective and damaging effects in heart remodeling. This ambiguity of the role of the immune system and inconsistent results of the recent clinical trials question the benefits of anti-inflammatory therapies during acute MI. The present review will summarize knowledge of the roles that different cells of the immune system play in the process of post-infarct cardiac healing. Data on the phenotype, active molecules and functions of the immune cells, based on the results of both experimental and clinical studies, will be provided. For some cellular subsets, such as macrophages, neutrophils, dendritic cells and lymphocytes, an anti-inflammatory activity has been attributed to the specific subpopulations. Activity of other cells, such as eosinophils, mast cells, natural killer (NK) cells and NKT cells has been shown to be highly dependent of the signals created by micro-environment. Also, new approaches for classification of cellular phenotypes based on the single-cell RNA sequencing allow better understanding of the phenotype of the cells involved in resolution of inflammation. Possible perspectives of immune-mediated therapy for AMI patients are discussed in the conclusion. We also outline unresolved questions that need to be solved in order to implement the current knowledge on the role of the immune cells in post-MI tissue repair into practice.