Reduction and activation of circulating dendritic cells in patients with decompensated heart failure

Role of angiotensin converting enzyme in pathogenesis associated with immunity in cardiovascular diseases

Angiotensin converting enzyme (ACE) is not only a critical component in the renin-angiotensin system (RAS), but also suggested as an important mediator for immune response and activity, such as immune cell mobilization, metabolism, biogenesis of immunoregulatory molecules, etc. The chronic duration of cardiovascular diseases (CVD) has been increasingly considered to be triggered by uncontrolled pathologic immune reactions from myeloid cells and lymphocytes. Considering the potential anti-inflammatory effect of the traditional antihypertensive ACE inhibitor (ACEi), we attempt to elucidate whether ACE and its catalytically relevant substances as well as signaling pathways play a role in the immunity-related pathogenesis of common CVD, such as arterial hypertension, atherosclerosis and arrythmias. ACEi was also reported to benefit the prognoses of COVID-19-positive patients with CVD, and COVID-19 disease with preexisting CVD or subsequent cardiovascular damage is featured by a significant influx of immune cells and proinflammatory molecules, suggesting that ACE may also participate in COVID-19 induced cardiovascular injury, because COVID-19 disease basically triggers an overactive pathologic immune response. Hopefully, the ACE inhibition and manipulation of those associated bioactive signals could supplement the current medicinal management of various CVD and bring greater benefit to patients' cardiovascular health.

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.

Body mass index-dependent immunological profile changes after left ventricular assist device implantation

Purpose

Infection is a common complication following left ventricular assist device (LVAD) implantation. Patients with obesity are particularly at risk due to their high percentage of adipose tissue and the resulting chronic inflammatory state and resulting immunological changes. This study investigated changes of immunological parameters in relation to body mass index (BMI) during the first year after LVAD implantation.

Methods

Blood samples were obtained prior to LVAD implantation and at 3 (1st FU), 6 (2nd FU) and 12 mo (3rd FU) after LVAD implantation. Patients were divided into three groups (normal weight: BMI of 18.5-24.9 kg/m2; n=12; pre-obesity: 25.0-29.9 kg/m2; n=15; obesity: ≥ 30.0 kg/m2; n=17) based on their BMI at the time of LVAD implantation. Flow cytometric analyses for CD4+ and CD8+ T cells, regulatory T cells (Tregs), B cells as well as dendritic cells (DCs) were performed.

Results

After LVAD implantation, obese patients (0.51 ± 0.20%) showed a higher proportion of overall DCs than normal-weight (0.28 ± 0.10%) and pre-obese patients (0.32 ± 0.11%, p<0.01) at 3rd FU. The proportion of BDCA3+ myeloid DCs was lower in obese patients (64.3 ± 26.5%) compared to normal-weight patients (82.7 ± 10.0%, pnormal-weight vs. obesity=0.05) at 2nd FU after LVAD implantation. The analysis of BDCA4+ plasmacytoid DCs revealed a reduced proportion in pre-obese (21.1 ± 9.8%, pnormal-weight vs. pre-obesity=0.01) and obese patients (23.7 ± 10.6%, pnormal-weight vs. obesity=0.05) compared to normal-weight patients (33.1 ± 8.2%) in the 1st FU. T cell analysis showed that CD4+ T cells of obese patients (62.4 ± 9.0%) significantly increased in comparison to pre-obese patients (52.7 ± 10.0%, ppre-obesity vs. obesity=0.05) and CD8+ T cells were lower in obese patients (31.8 ± 8.5%) than in normal-weight patients (42.4 ± 14.2%; pnormal-weight vs. obesity=0.04) at the 3rd FU. Furthermore, we observed significantly reduced proportions of Tregs in pre-obese patients compared to normal-weight and obese patients at 2nd FU (p=0.02) and 3rd FU (p=0.01) after LVAD implantation.

Conclusion

This study reported changes of the innate and adaptive immune system of pre-obese and obese compared to normal-weight patients one year after LVAD implantation. DCs and their subsets, CD8+ T cells and Tregs were affected immune cell populations that indicate immunological changes which might increase the incidence of postoperative infection.

Identifying immune cell infiltration and diagnostic biomarkers in heart failure and osteoarthritis by bioinformatics analysis

Heart failure (HF) and osteoarthritis (OA) are medical conditions that can significantly impact daily activities. Evidence has shown that HF and OA may share some pathogenic mechanisms. However, the underlying genomic mechanisms remain unclear. This study aimed to explore the underlying molecular mechanism and identify diagnostic biomarkers for HF and OA. With the cutoff criteria of fold change (FC) > 1.3 and P < .05, 920, 1500, 2195, and 2164 differentially expressed genes (DEGs) were identified in GSE57338, GSE116250, GSE114007, and GSE169077, respectively. After making the intersection of DEGs, we obtained 90 upregulated DEGs and 51 downregulated DEGs in HF datasets and 115 upregulated DEGs and 75 downregulated DEGs in OA datasets. Afterward, we conducted genome ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, protein-protein interaction (PPI) networks, and hub genes screening based on DEGs. Then, 4 common DEGs (fibroblast activation protein alpha [FAP], secreted frizzled-related protein 4 (SFRP4), Thy-1 cell surface antigen (THY1), matrix remodeling associated 5 [MXRA5]) between HF and OA were screened and validated in GSE5406 and GSE113825 datasets, based on which we established the support vector machine (SVM) models. The combined area under the receiver operating characteristic curve (AUC) of THY1, FAP, SFRP4, and MXRA5 in the HF training and test sets reached 0.949 and 0.928. While in the OA training set and test set, the combined AUC of THY1, FAP, SFRP4, and MXRA5 reached 1 and 1, respectively. The analysis of immune cells in HF revealed high levels of dendritic cell (DC), B cells, natural killer T cell (NKT), Type 1 regulatory T cell (Tr1), cytotoxic T cell (Tc), exhausted T cell (Tex), and mucosal-associated invariant T cell (MAIT), while displaying lower levels of monocytes, macrophages, NK, CD4 + T, gamma delta T (γδ T), T helper type 1 (Th1), T helper type 2 (Th2), and effector memory T cell (Tem). Moreover, the 4 common DEGs were positively correlated with DCs and B cells and negatively correlated with γδ T. In OA patients, the abundance of monocyte, macrophage, CD4 + naïve, and natural T regulatory cell (nTreg) was higher, while the infiltration of CD8 + T, γδ T, CD8 + naïve, and MAIT was lower. The expression of THY1 and FAP was significantly correlated with macrophage, CD8 + T, nTreg, and CD8 + naïve. SFRP4 was correlated with monocyte, CD8 + T, γδ T, CD4 + naïve, nTreg, CD8 + naïve and MAIT. MXRA5 was correlated with macrophage, CD8 + T, nTreg and CD8 + naïve. FAP, THY1, MXRA5, and SFRP4 may be diagnostic biomarkers for both HF and OA, and their correlation with immune cell infiltrations suggests shared immune pathogenesis.

Distribution and maturation state of peripheral blood dendritic cells in children with primary hypertension

Dendritic cells (DCs) play an important role in T cell alterations in primary hypertension (PH). We determined the numbers and maturation markers of peripheral blood total DCs (tDCs), myeloid cells (mDCs), and plasmacytoid cells (pDCs) and their association with hypertension-mediated organ damage (HMOD) markers and selected immune parameters in 30 adolescents with white coat hypertension (WCH), 25 adolescents with PH and a group of 35 age- and sex-matched children with normotension. Using multicolor flow cytometry, expression of maturation markers (CD86 and CD83) in tDCs (Lin1^-/HLA-DR⁺), myeloid DCs (Lin1^-/HLA-DR⁺/CD11c⁺) (mDCs), and plasmacytoid DCs (Lin1^-/HLA-DR⁺/CD123⁺) (pDCs) and the distribution of peripheral Th17-bearing and T-reg cells were defined. In subjects with hypertension, carotid intima-media thickness (cIMT), left ventricular mass index (LVMI), and pulse wave velocity (PWV) were assessed. Compared with WCH and subjects with normotension, subjects with hypertension had reduced tDC and pDC numbers, an increased percentage of mDC subsets, an elevated mDC/pDC ratio, an increased population of mature mDC and pDC subsets bearing CD83 of high density, a decreased subset of CD86-bearing pDCs, and increased expression of DC activation markers (HLA-DR, CD86), as well as CD11c (mDCs) and CD123 (pDCs). PWV, LVMI, and cIMT values correlated negatively with tDCs and pDCs and positively with mDC numbers. Expression of DC maturation/activation markers (CD83, CD86, HLA-DR, CD11c, and CD123) correlated positively with PWV. Certain DC characteristics of WCH subjects resembled those of PH subjects (decreased tDC frequency and upregulation of activation marker expression). These changes correlated with HMOD. WCH subjects presented a DC phenotype that was intermediate between the normotensive and hypertensive phenotypes.

Regulatory T Cells in Chronic Heart Failure

Heart failure is a global problem with high hospitalization and mortality rates. Inflammation and immune dysfunction are involved in this disease. Owing to their unique function, regulatory T cells (Tregs) have reacquired attention recently. They participate in immunoregulation and tissue repair in the pathophysiology of heart failure. Tregs are beneficial in heart by suppressing excessive inflammatory responses and promoting stable scar formation in the early stage of heart injury. However, in chronic heart failure, the phenotypes and functions of Tregs changed. They transformed into an antiangiogenic and profibrotic cell type. In this review, we summarized the functions of Tregs in the development of chronic heart failure first. Then, we focused on the interactions between Tregs and their target cells. The target cells of Tregs include immune cells (such as monocytes/macrophages, dendritic cells, T cells, and B cells) and parenchymal cells (such as cardiomyocytes, fibroblasts, and endothelial cells). Next-generation sequencing and gene editing technology make immunotherapy of heart failure possible. So, prospective therapeutic approaches based on Tregs in chronic heart failure had also been evaluated.

The P-selectin and PSGL-1 axis accelerates atherosclerosis via activation of dendritic cells by the TLR4 signaling pathway

P-selectin and dendritic cells (DCs) are associated with atherosclerosis. However, their interactions in this setting are undefined. Herein, we investigated the role of P-selectin and its receptor P-selectin glycoprotein ligand (PSGL)-1 on atherosclerosis via activation of DCs. In the current study, a total of 34 patients with ST elevation myocardial infarction (STEMI) and 34 healthy control subjects were enrolled. Serum concentration of P-selectin was higher and the myeloid DC/plasmacytoid DC (mDC/pDC) ratio was lower in STEMI patients than in normal individuals. Interestingly, in STEMI patients, P-selectin was decreased and the mDC/pDC ratio was increased at 5–7 days after successful percutaneous coronary intervention, as compared with values on admission. Serum P-selectin was inversely correlated with the mDC/pDC ratio. Moreover, ApoE^−/−P^−/− and ApoE^−/−PSGL-1^−/− mice developed small atherosclerotic plaques after feeding of a western diet for 12 weeks and DC infiltration was significantly reduced. P-selectin stimulation markedly induced phenotypic maturation, enhanced secretion of inflammatory cytokines, communication with T cells, and the adhesion and migration of DCs. In vivo, DC maturation was significantly attenuated in P-selectin and PSGL1 knockout mice under hypercholesterolemic and inflammatory conditions. These effects were associated with the activation of myeloid differentiation primary response 88 (MYD88)-dependent and MyD88-independent Toll-like receptor 4 (TLR4) signaling pathways. Taken together, binding of P-selectin to PSGL-1 on DCs contributes to atherosclerosis progression via DC activation via the TLR4 signaling pathway.

Increased Plasma Soluble Fractalkine in Patients with Chronic Heart Failure and Its Clinical Significance

Fractalkine has been reported to play an important role in the pathophysiology of various cardiovascular disorders. This research aims to study the change of soluble fractalkine (sFKN) in plasma level of patients with chronic heart failure (CHF) and evaluate its prognostic value.A total of 96 patients with CHF and 45 healthy subjects were included in this study. The plasma levels of sFKN, brain natriuretic peptide (BNP), and Interleukin-18 (IL-18) were determined by ELISA kits when they were first admitted to the hospital. Left ventricular ejection fraction (LVEF) was measured by echocardiogram. Rehospitalization status within 1 year after the first hospitalization was also recorded.The plasma levels of sFKN, BNP, and IL-18 in patients with CHF were significantly higher than in the control group (P < 0.05). The concentrations of sFKN and BNP were increased with the severity of heart failure classified by NYHA classification (P < 0.05). There were no statistical differences among all CHF subgroups classified by etiology (P > 0.05). Plasma sFKN level in CHF group was positively correlated with BNP (r = 0.441, P < 0.001) and IL-18 (r = 0.592, P < 0.001). Receiver operating characteristic curve analysis showed that area under the curve values of FKN, BNP, and IL-18 were 0.885 (95%CI: 0.810 to 0.960, P < 0.001), 0.889 (95%CI: 0.842 to 0.956, P < 0.001), and 0.878 (95%CI: 0.801-0.954, P < 0.001), respectively. The concentrations of sFKN and BNP were increased in patients readmitted more than once within 1 year (P < 0.05).

Immunopharmacology of Post-Myocardial Infarction and Heart Failure Medications

The immune system responds to acute tissue damage after myocardial infarction (MI) and orchestrates healing and recovery of the heart. However, excessive inflammation may lead to additional tissue damage and fibrosis and exacerbate subsequent functional impairment, leading to heart failure. The appreciation of the immune system as a crucial factor after MI has led to a surge of clinical trials investigating the potential benefits of immunomodulatory agents previously used in hyper-inflammatory conditions, such as autoimmune disease. While the major goal of routine post-MI pharmacotherapy is to support heart function by ensuring appropriate blood pressure and cardiac output to meet the demands of the body, several drug classes also affect a range of immunological pathways and modulate the post-MI immune response, which is crucial to take into account when designing future immunomodulatory trials. This review outlines how routine post-MI pharmacotherapy affects the immune response and may thus influence post-MI outcomes and development towards heart failure. Current key drug classes are discussed, including platelet inhibitors, statins, β-blockers, and renin⁻angiotensin⁻aldosterone inhibitors.

Inflammation in Right Ventricular Failure: Does It Matter?

Right ventricular (RV) failure is a common consequence of acute and chronic RV overload of pressure, such as after pulmonary embolism and pulmonary hypertension. It has been recently realized that symptomatology and survival of patients with pulmonary hypertension are essentially determined by RV function adaptation to increased afterload. Therefore, improvement of RV function and reversal of RV failure are treatment goals. Currently, the pathophysiology and the pathobiology underlying RV failure remain largely unknown. A better understanding of the pathophysiological processes involved in RV failure is needed, as there is no proven treatment for this disease at the moment. The present review aims to summarize the current understanding of the pathogenesis of RV failure, focusing on inflammation. We attempt to formally emphasize the importance of inflammation and associated representative inflammatory molecules and cells in the primum movens and development of RV failure in humans and in experimental models. We present inflammatory biomarkers and immune mediators involved in RV failure. We focus on inflammatory mediators and cells which seem to correlate with the deterioration of RV function and also explain how all these inflammatory mediators and cells might impact RV function adaptation to increased afterload. Finally, we also discuss the evidence on potential beneficial effects of targeted anti-inflammatory agents in the setting of acute and chronic RV failure.

Long-term alterations in monocyte function after elective cardiac surgery

Optimal immunological homoeostasis determines the long-term recovery of patients in the postoperative period. The functional adaptability of monocytes plays a pivotal role in adjusting the host's response to an insult, immunostasis and long-term health, and may help to determine successful recovery. We undertook a longitudinal analysis of the functional adaptability of monocytes in 20 patients undergoing heart surgery with cardiopulmonary bypass, as a model of severe stress. Using each patient's pre-cardiopulmonary bypass data as a baseline, we investigated the characteristics of peripheral blood monocytes' functional plasticity in-vitro before elective bypass, and three months afterwards. Approximately 30% of subjects showed diminished monocyte plasticity, as demonstrated by decreased monocyte differentiation into dendritic cells three months after bypass. Diminished monocyte functional plasticity was related to over-production of macrophage colony-stimulating factor. Adding a neutralising antibody to macrophage colony-stimulating factor corrected the monocytes' differentiation defect. Finally, patients with reduced monocyte plasticity had significantly elevated serum C-reactive protein, with a concomitant increase in cytomegalovirus IgG antibody titres, suggestive of the acquisition of immuno-suppressive traits. Our study shows that severe surgical stress resulted in a lasting immunological defect in individuals who had seemingly recovered.

Impact of Ivabradine on Inflammatory Markers in Chronic Heart Failure

Background. Inflammation plays a crucial role in the progression of chronic heart failure (CHF). Ivabradine is known to reduce the morbidity and mortality of patients with CHF under certain conditions. Beyond the reduction of heart rate, only limited knowledge exists about potential anti-inflammatory effects of ivabradine that might contribute to its benefit in CHF. Thus, the present study aimed to investigate the effect of ivabradine on systemic inflammation. Methods. In the present study, 33 patients with CHF due to dilated, ischemic, and hypertensive cardiomyopathy were treated with ivabradine according to the guidelines of the European Society of Cardiology (ESC). A number of circulating dendritic cells as well as inflammatory mediators were investigated using FACS analysis and ELISA, respectively, before and during ivabradine therapy. Results. Treatment with ivabradine resulted in a significant improvement of CHF symptoms as well as an increase in left ventricular ejection fraction. Moreover, ivabradine treatment led to a significant reduction of TNF-alpha (TNF-α) serum levels and a reconstitution of circulating dendritic cells which are known to be reduced in patients with CHF. Conclusion. We show that treatment with ivabradine in patients with CHF resulted in an improvement of HF symptoms and ejection fraction as well as a normalization of inflammatory mediators.

The Ability of Precursory Monocytes (MO) to Differentiate Varies Among Individuals But Is Stable Over Time

Background

The ability to generate dendritic cells (DCs) from precursory monocytes (MOs) was a breakthrough in the field of immunology. However, it is unknown whether the ability of MOs to differentiate into immature DCs (iDCs) differs across subjects or is time dependent. Given that the study of immune system function is gaining recognition in the field of clinical medicine, it is important to know how certain immunologic features vary over time.

Material/Methods

This study investigates how much individuals’ MO-to-iDC differentiation potential changes over time. We estimated this potential by measuring the expression of an iDC marker (CD1a), cytokine secretion (interleukin [IL]-12p70), and the ability of IL-4 and granulocyte macrophage colony-stimulating factor (GM-CSF) differentiation MOs to stimulate T cells. We collected MOs obtained from different subjects (n=17) at least 1 month apart. Furthermore, we investigated several variables (expression for cytokine receptors, timing, and emergence of DC-related transcriptional factor PU.1).

Results

The ability of MOs to become DCs under the influence of IL-4 and GM-CSF varied greatly between individuals (range of CD1a expression, 20–80%) but was stable over time (change of CD1a expression between sampling, ~5%). A similar pattern emerged when production of IL-12p70 was analyzed. The ability to stimulate T cells was variable and depended on the T-cell source. The ability of MOs to become iDCs was not linked to the surface expression of receptors for IL-4 and GM-CSF but rather to the activation of PU.1 in the precursory MO. It took 5 days for all committed MOs to become iDCs under in vitro influence of IL-4 and GM-CSF.

Conclusions

We concluded that the potential of MO to become iDC is an individual feature and depends on activation of PU.1.

Dendritic Cells and Their Role in Cardiovascular Diseases: A View on Human Studies

The antigen-presenting dendritic cells (DCs) are key to the immunological response, with different functions ascribed ranging from cellular immune activation to induction of tolerance. Such immunological responses are involved in the pathophysiological mechanisms of cardiovascular diseases, with DCs shown to play a role in atherosclerosis, hypertension, and heart failure and most notably following heart transplantation. A better understanding of the interplay between the immune system and cardiovascular diseases will therefore be critical for developing novel therapeutic treatments as well as innovative monitoring tools for disease progression. As such, the present review will provide an overview of DCs involvement in the pathophysiology of cardiovascular diseases and how targeting these cells may have beneficial effects for the prognosis of patients.

Decrease in circulating plasmacytoid dendritic cells during short-term systemic normobaric hypoxia

BACKGROUND

During exposure to high altitude, the immune system is altered. During hypoxia, an increase in interleukin (IL)-6 and high sensitivity C-reactive protein (hs-CRP), and an increase in natural killer cells and decrease in T cells in blood was shown. However, the impact of hypoxia on dendritic cells has not been investigated yet.

MATERIAL AND METHODS

Twelve healthy volunteers were subjected to a transient normobaric hypoxia for 6·5 h simulating an oxygen concentration at 5500 m. During exposure to hypoxia, blood samples were collected and analysed by flow cytometrical cell sorting (FACS) for circulating myeloid (mDCs) and plasmacytoid (pDCs) DCs. Serum levels of IL-6 and tumour necrosis factor (TNF)-α were analysed. In a cell culture hypoxia chamber, blood samples were subjected to the same hypoxia and analysed regarding DCs.

RESULTS

Exposure to normobaric hypoxia induced a significant decrease in circulating pDCs about 45% (P = 0·001) but not of mDC compared to baseline normoxia. Furthermore, we observed a significant increase of TNF-α about 340% (P = 0·03) and of IL-6 about 286% (P = 0·002). In cell culture experiments exposure of blood to hypoxia led to no significant changes in DCs, so that a direct cytotoxic effect was excluded. During hypoxia, we observed a transient increase in stromal-derived factor 1 (SDF-1) which is important for pDC tissue recruitment.

CONCLUSIONS

We show a significant decrease in circulating pDCs during hypoxia in parallel to a pro-inflammatory response. Further studies are necessary to evaluate whether the decrease in circulating pDCs might be the result of an enhanced tissue recruitment.

Plasmacytoid dendritic cells: biomarkers or potential therapeutic targets in atherosclerosis?

Plasmacytoid dendritic cells (pDCs) represent a unique subset of dendritic cells that play distinct and critical roles in the immune response. Importantly, pDCs play a pivotal role in several chronic autoimmune diseases strongly characterized by an increased risk of vascular pathology. Clinical studies have shown that pDCs are detectable in atherosclerotic plaques and others have suggested an association between reduced numbers of circulating pDCs and cardiovascular events. Although the causal relationship between pDCs and atherosclerosis is still uncertain, recent results from mouse models are starting to define the specific role(s) of pDCs in the disease process. In this review, we will discuss the role of pDCs in innate and adaptive immunity, the emerging evidence demonstrating the contribution of pDCs to vascular pathology and we will consider the possible impact of pDCs on the acceleration of atherosclerosis in chronic inflammatory autoimmune diseases. Finally, we will discuss how pDCs could be targeted for therapeutic utility.

Transient reduction and activation of circulating dendritic cells in patients with acute myocardial infarction

BACKGROUND

Dendritic cells (DCs) are highly potent professional antigen-presenting cells that play a central role in initiating the primary immune response. Accumulating evidence suggests that immune-mediated inflammation plays an important role in the pathophysiology of AMI, but the mechanism that triggers such immune responses is unknown.

METHODS

Using multi-color flow-cytometry, we determined the numbers of circulating myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) in patients with AMI (n = 26) or stable angina pectoris (SAP) (n = 19), and in age-matched control subjects (n = 19). The DC activation markers CD40 and CD83 were also measured.

RESULTS

On admission, circulating mDC and pDC counts were significantly lower in AMI patients compared to control subjects and SAP patients (mDC, P < 0.01; pDC, P < 0.05). The activation markers of mDCs in AMI patients were significantly higher and returned to the levels of control subjects or SAP patients 3 days after AMI (mDC, P < 0.05; pDC, P < 0.05). Reductions of circulating mDC and pDC numbers were restored 7 days after the onset of AMI. Furthermore, we found that the recovery of the circulating DC numbers 14 days after AMI was correlated with the alterations of creatine kinase-MB (CK-MB) (mDC, r = 0.48, P < 0.05; pDC, r=0.52, P < 0.01) and brain natriuretic peptide (BNP) (mDC, r = 0.53, P < 0.01; pDC, r = 0.51, P < 0.01).

CONCLUSION

Our findings suggest that the transient reduction and activation of circulating DCs may play important roles in the pathophysiology of myocardial injury after AMI.

Plasmacytoid dendritic cells: from heart to vessels

Cardiovascular diseases, formerly only attributed to the alterations of the stromal component, are now recognized as immune-based pathologies. Plasmacytoid Dendritic Cells (pDCs) are important immune orchestrators in heart and vessels. They highly produce IFN type I that promote the polarization of T cells towards a Th1 phenotype; however, pDCs can also participate to suppressive networks via the recruitment of T regulatory cells that downmodulate proinflammatory responses. pDCs populate the vessel wall layers during pathological conditions, such as atherosclerosis. It is thus clear that a better identification of pDCs activity in cardiovascular diseases can not only elucidate pathological mechanisms but also lead to new therapeutic approaches.