Altered Chemokine Receptor Profile on Circulating Leukocytes in Human Heart Failure

Adaptive Immune Responses in 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⁺CD28^null 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.

Macrophages represent the major pool of IL-7Rα expressing cells in patients with myocarditis

Myocarditis is characterized by infiltration and activation of cytokine as well as chemokine receptors frequently producing heart failure. Causes are often infections triggering inflammatory and immune responses but these initial lines of defense might be finally disastrous. To identify mediators we screened various receptors by confocal microscopy and identified cardiac interleukin-7 (IL-7) receptor-α (IL-7Rα) expressing cells in patients with myocarditis. IL-7Rα+ cells were analyzed by markers for leukocytes (CD45), B cells (CD19), T cells (CD3, CD4, CD8) and macrophages (CD68, CD163, CD206). Immune cells were hardly detected in controls. In patients with myocarditis main inflammatory populations consisted of macrophages and T cells. B cells were hardly present. 90% of CD68+ macrophages but less than 20% of CD3+ T cells were IL-7Rα+. This was surprising since T and B lymphocytes are generally regarded as the major IL-7Rα+ cells. Since IL-7 acts as a chemokine, the expression of its receptor might orchestrate cardiac macrophage infiltration. In contrast, consumption of IL-7 by IL-7Rα+ cardiac macrophages might potentially prevent a certain overshooting immune reaction and sepsis by reducing proliferation and survival of lymphocytes. Our data suggest a participation of IL-7Rα+ macrophages in the development of myocarditis and heart failure.

CXCR3 regulates CD4+ T cell cardiotropism in pressure overload-induced cardiac dysfunction

Heart failure (HF) is associated in humans and mice with increased circulating levels of CXCL9 and CXCL10, chemokine ligands of the CXCR3 receptor, predominantly expressed on CD4+ Th1 cells. Chemokine engagement of receptors is required for T cell integrin activation and recruitment to sites of inflammation. Th1 cells drive adverse cardiac remodeling in pressure overload-induced cardiac dysfunction, and mice lacking the integrin ligand ICAM-1 show defective T cell recruitment to the heart. Here, we show that CXCR3+ T cells infiltrate the heart in humans and mice with pressure overload-induced cardiac dysfunction. Genetic deletion of CXCR3 disrupts CD4+ T cell heart infiltration and prevents adverse cardiac remodeling. We demonstrate that cardiac fibroblasts and cardiac myeloid cells that include resident and infiltrated macrophages are the source of CXCL9 and CXCL10, which mechanistically promote Th1 cell adhesion to ICAM-1 under shear conditions in a CXCR3-dependent manner. To our knowledge, our findings identify a previously unrecognized role for CXCR3 in Th1 cell recruitment into the heart in pressure overload-induced cardiac dysfunction.

Emerging importance of chemokine receptor CXCR3 and its ligands in cardiovascular diseases

The CXC chemokines, CXCL4, -9, -10, -11, CXCL4L1, and the CC chemokine CCL21, activate CXC chemokine receptor 3 (CXCR3), a cell-surface G protein-coupled receptor expressed mainly by Th1 cells, cytotoxic T (Tc) cells and NK cells that have a key role in immunity and inflammation. However, CXCR3 is also expressed by vascular smooth muscle and endothelial cells, and appears to be important in controlling physiological vascular function. In the last decade, evidence from pre-clinical and clinical studies has revealed the participation of CXCR3 and its ligands in multiple cardiovascular diseases (CVDs) of different aetiologies including atherosclerosis, hypertension, cardiac hypertrophy and heart failure, as well as in heart transplant rejection and transplant coronary artery disease (CAD). CXCR3 ligands have also proven to be valid biomarkers for the development of heart failure and left ventricular dysfunction, suggesting an underlining pathophysiological relation between levels of these chemokines and the development of adverse cardiac remodelling. The observation that several of the above-mentioned chemokines exert biological actions independent of CXCR3 provides both opportunities and challenges for developing effective drug strategies. In this review, we provide evidence to support our contention that CXCR3 and its ligands actively participate in the development and progression of CVDs, and may additionally have utility as diagnostic and prognostic biomarkers.

"The enemy within". How to identify chronic diseases induced-protein metabolism impairment and its possible pharmacological treatment

Recent clinical and experimental data show that considerable impairment of protein metabolism occurs in patients with chronic diseases such as heart failure. However, too often the extent of impairment is under-estimated or ignored by most clinicians and no therapy is considered leading to progressive loss of body proteins, increase morbidity, hospital stay and mortality. This paper illustrates the possible biological markers to evaluate general protein metabolism, including quantification of related damage and possible improvement of the metabolism using specific therapeutical metabolic strategies recently studied in a clinical setting.

Systemic inflammation and cell activation reflects morbidity in chronic heart failure

Chronic heart failure (CHF) leads to complex effects distant from the heart. As these changes may be reflected in the balance of systemic inflammatory and fibrotic immunomodulators we measured these potential biomarkers in ambulatory CHF patients. Using the New York Heart Association (NYHA; levels II-IV) functional classification, 30 CHF patients were compared with 21 age and gender matched controls. Peripheral blood levels of regulatory cytokines (TNF-α, TGF-β, KGF, IL-8, IL-10 and IL-12) and markers of cellular activation (CD11b, CD16, CD18, CD34, HLADR, CXCR1 and CCR5) were analysed by ELISA and flow cytometry, respectively. NYHA classification, which reflected increasing pulmonary microvascular pressure (E:E') but not ejection fraction, was positively associated with TGF-β and IL-10 (p≤0.03). Similarly, monocytes, as well as cell surface expression of the neutrophil adhesion molecule CD11b, and the macrophage complement receptor complex (CD11b/CD18), were increased in CHF patients (p≤0.03), while the chemokine receptor CXCR1 was decreased on cells of CHF patients. Twenty month follow-up of CHF subjects identified monocyte number as a powerful prognostic factor for cardio-pulmonary adverse events (p=0.001); however, no concurrent relationship with cellular activation marker expression was found. In subjects with CHF, monocytes, TGF-β, IL-10, CD11b/CD18 and CXCR1 expression in peripheral blood may act as novel biomarkers of immune activation and remodelling. Given the importance of dyspnea and the relationship of pulmonary microvascular pressure to the NYHA classification, we suggest these findings may reflect a contribution by the lung.

Direct gene transfer with IP-10 mutant ameliorates mouse CVB3-induced myocarditis by blunting Th1 immune responses

Background

Myocarditis is an inflammation of the myocardium that often follows the enterovirus infections, with coxsackievirus B3 (CVB3) being the most dominant etiologic agent. We and other groups previously reported that chemokine IP-10 was significantly induced in the heart tissue of CVB3-infected mice and contributed to the migration of massive inflammatory cells into the myocardium, which represents one of the most important mechanisms of viral myocarditis. To evaluate the direct effect of IP-10 on the inflammatory responses in CVB3 myocarditis, herein an IP-10 mutant deprived of chemo-attractant function was introduced into mice to antagonize the endogenous IP-10 activity, and its therapeutic effect on CVB3-induced myocarditis was evaluated.

Methodology/Principal Findings

The depletion mutant pIP-10-AT, with an additional methionine after removal of the 5 N-terminal amino acids, was genetically constructed and intramuscularly injected into BALB/c mice after CVB3 infection. Compared with vector or no treatment, pIP-10-AT treatment had significantly reduced heart/body weight ratio and serum CK-MB level, increased survival rate and improved heart histopathology, suggesting an ameliorated myocarditis. This therapeutic effect was not attributable to an enhanced viral clearance, but to a blunted Th1 immune response, as evidenced by significantly decreased splenic CD4⁺/CD8⁺IFN-γ⁺ T cell percentages and reduced myocardial Th1 cytokine levels.

Conclusion/Significance

Our findings constitute the first preclinical data indicating that interfering in vivo IP-10 activity could ameliorate CVB3 induced myocarditis. This strategy may represent as a new therapeutic approach in treating viral myocarditis.

Gene expression profiles in peripheral blood mononuclear cells of chronic heart failure patients

The present study was aimed at identifying chronic heart failure (CHF) biomarkers from peripheral blood mononuclear cells (PBMCs) in patients with ischemic (ICM) and nonischemic dilated (NIDCM) cardiomyopathy. PBMC gene expression profiling was performed by Affymetrix in two patient groups, 1) ICM (n = 12) and 2) NIDCM (n = 12) New York Heart Association (NYHA) III/IV CHF patients, vs. 3) age- and sex-matched control subjects (n = 12). Extracted RNAs were then pooled and hybridized to a total of 11 microarrays. Gene ontology (GO) analysis separated gene profiling into functional classes. Prediction analysis of microarrays (PAM) and significance analysis of microarrays (SAM) were utilized in order to identify a molecular signature. Candidate markers were validated by quantitative real-time polymerase chain reaction. We identified a gene expression profiling that distinguished between CHF patients and control subjects. Interestingly, among the set of genes constituting the signature, chemokine receptor (CCR2, CX(3)CR1) and early growth response (EGR1, 2, 3) family members were found to be upregulated in CHF patients vs. control subjects and to be part of a gene network. Such findings were strengthened by the analysis of an additional 26 CHF patients (n = 14 ICM and n = 12 NIDCM), which yielded similar results. The present study represents the first large-scale gene expression analysis of CHF patient PBMCs that identified a molecular signature of CHF and putative biomarkers of CHF, i.e., chemokine receptor and EGR family members. Furthermore, EGR1 expression levels can discriminate between ICM and NIDCM CHF patients.

The immune system and chronic heart failure: is the heart in control?

Despite current treatment options, the clinical course of patients with chronic heart failure is notoriously difficult to predict. Among those with similar etiologies, ejection fractions, and patient demographics, our understanding of why such variations in outcomes exist remains limited. Evidence that has been progressively gathered implicates an important role of the immune system in the propagation of heart failure. This has been derived mainly from observations that cytokines are progressively elevated in patients with poor outcomes. However, attempts at introducing various immunomodulatory therapies as a new treatment strategy have been largely unsuccessful to date. This possibly reflects a failure in recognizing the complexity of the immune system's role in chronic heart failure, which has led to an oversimplified approach to treatment. This review critically analyzes the immune treatments attempted to date and hypothesizes what is required to develop a successful future treatment strategy.