Complement activation in patients with congestive heart failure: effect of high-dose intravenous immunoglobulin treatment

Cytotoxicity and toxicoproteomics analysis of thiazolidinedione exposure in human-derived cardiomyocytes

Thiazolidinediones (TZDs) (e.g. pioglitazone and rosiglitazone), known insulin sensitiser agents for type II diabetes mellitus, exhibit controversial effects on cardiac tissue. Despite consensus on their association with increased heart failure risk, limiting TZD use in diabetes management, the underlying mechanisms remain uncharacterised. Herein, we report a comprehensive in vitro investigation utilising a novel toxicoproteomics pipeline coupled with cytotoxicity assays in human adult cardiomyocytes to elucidate mechanistic insights into TZD cardiotoxicity. The cytotoxicity assay findings showed a significant loss of mitochondrial adenosine triphosphate production upon exposure to either TZD agents, which may underpin TZD cardiotoxicity. Our toxicoproteomics analysis revealed that mitochondrial dysfunction primarily stems from oxidative phosphorylation impairment, with distinct signalling mechanisms observed for both agents. The type of cell death differed strikingly between the two agents, with rosiglitazone exhibiting features of caspase-dependent apoptosis and pioglitazone implicating mitochondrial-mediated necroptosis, as evidenced by the protein upregulation in the phosphoglycerate mutase family 5-dynamin-related protein 1 axis. Furthermore, our analysis revealed additional mechanistic aspects of cardiotoxicity, showcasing drug specificity. The downregulation of various proteins involved in protein machinery and protein processing in the endoplasmic reticulum was observed in rosiglitazone-treated cells, implicating proteostasis in the rosiglitazone cardiotoxicity. Regarding pioglitazone, the findings suggested the potential activation of the interplay between the complement and coagulation systems and the disruption of the cytoskeletal architecture, which was primarily mediated through the integrin-signalling pathways responsible for pioglitazone-induced myocardial contractile failure. Collectively, this study unlocks substantial mechanistic insight into TZD cardiotoxicity, providing the rationale for future optimisation of antidiabetic therapies.

Pharmacodynamics and Mechanism of Astragali Radix and Anemarrhenae Rhizoma in Treating Chronic Heart Failure by Inhibiting Complement Activation

Astragali radix (AR) and anemarrhenae rhizoma (AAR) are used clinically in Chinese medicine for the treatment of chronic heart failure (CHF), but the exact therapeutic mechanism is unclear. In this study, a total of 60 male C57BL/6 mice were divided into 5 groups, namely sham, model, AR, AAR, and AR-AAR. In the sham group, the chest was opened without ligation. In the other groups, the chest was opened and the transverse aorta was ligated to construct the transverse aortic constriction model. After 8 weeks of feeding, mice were given medicines by gavage for 4 weeks. Left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) were detected by echocardiography. Heart weight index (HWI) and wheat germ agglutinin staining were used to evaluate cardiac hypertrophy. Hematoxylin-eosin staining was used to observe the pathological morphology of myocardial tissue. Masson staining was used to evaluate myocardial fibrosis. The content of serum brain natriuretic peptide (BNP) was detected by enzyme-linked immunosorbent assay kit. The content of serum immunoglobulin G (IgG) was detected by immunoturbidimetry. The mechanism of AR-AAR in the treatment of CHF was explored by proteomics. Western blot was used to detect the protein expressions of complement component 1s (C1s), complement component 9 (C9), and terminal complement complex 5b-9 (C5b-9). The results show that AR-AAR inhibits the expression of complement proteins C1s, C9, and C5b-9 by inhibiting the production of IgG antibodies from B cell activation, which further inhibits the complement activation, attenuates myocardial fibrosis, reduces HWI and cardiomyocyte cross-sectional area, improves cardiomyocyte injury, reduces serum BNP release, elevates LVEF and LVFS, improves cardiac function, and exerts myocardial protection.

Identification and analysis of differential miRNA-mRNA interactions in coronary heart disease: an experimental screening approach

Objective

This aim of this study is to screen the differential molecules of kidney deficiency and blood stasis (KDBS) syndrome in coronary heart disease by high-throughput sequencing. In addition, the study aims to verify the alterations in the expression levels of miR-4685-3p and its regulated downstream, namely, C1QC, C4, and C5, using quantitative polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA), and to determine whether the complement and coagulation cascade pathway is the specific pathogenic pathway.

Methods

Patients diagnosed with unstable angina pectoris with KDBS syndrome, patients with non-kidney deficiency blood stasis (NKDBS) syndrome, and a Normal group were recruited. The clinical symptoms of each group were further analyzed. Illumina's NextSeq 2000 sequencing platform and FastQC software were used for RNA sequencing and quality control. DESeq software was used for differential gene expression (DGE) analysis. qPCR and ELISA verification were performed on DGE analysis.

Results

The DGE profiles of 77 miRNA and 331 mRNA were selected. The GO enrichment analysis comprised 43 biological processes, 49 cell components, and 42 molecular functions. The KEGG enrichment results included 40 KEGG pathways. The PCR results showed that, compared with the Normal group, the miR-4685-3p levels decreased in the CHD_KDBS group (P = 0.001), and were found to be lower than those observed in the CHD_NKDBS group. The downstream mRNA C1 regulated by miR-4685-3p showed an increasing trend in the CHD_KDBS group, which was higher than that in the Normal group (P = 0.0019). The mRNA C4 and C5 in the CHD_KDBS group showed an upward trend, but the difference was not statistically significant. ELISA was utilized for the detection of proteins associated with the complement and coagulation cascade pathway. It was found that the expression level of C1 was significantly upregulated in the CHD_KDBS group compared with the Normal group (P < 0.0001), which was seen to be higher than that in the CHD_NKDBS group (P < 0.0001). The expression levels of C4 and C5 in the CHD_KDBS group were significantly lower than the Normal group, and were lower than that in the CHD_NKDBS group (P < 0.0001).

Conclusion

The occurrence of CHD_KDBS might be related to the activation of the complement and coagulation cascade pathway, which is demonstrated by the observed decrease in miR-4685-3p and the subsequent upregulation of its downstream C1QC. In addition, the expression levels of complement C4 and C5 were found to be decreased, which provided a research basis for the prevention and treatment of this disease.

Complement component C1q initiates extrinsic coagulation via the receptor for the globular head of C1q in adventitial fibroblasts and vascular smooth muscle cells

BACKGROUND

Vascular diseases are highly associated with inflammation and thrombosis. Elucidating links between these two processes may provide a clearer understanding of these diseases, allowing for the design of more effective treatments. The activation of complement component 1 (C1) is a crucial contributor to innate immunity and is associated with significant concentrations of circulating C1q. Many pathological pathways initiate when C1q interacts with gC1qR. This interaction plays a major role in inflammation observed during atherosclerosis and the initiation of intrinsic coagulation. However, the effects of C1 and the role of C1q/gC1qR on extrinsic coagulation, which is the more physiologically relevant coagulation arm, has not been studied. We hypothesized that C1q binding to gC1qR enhances the expression of tissue factor (TF) in adventitial fibroblasts and vascular smooth muscle cells, the primary TF bearing cells in the body.

METHODS

Using an enzyme-linked immunosorbent assay approach, TF expression and the role of gC1qR was observed. Cells were conditioned for 1 h with C1q or a gC1qR blocker and C1q, to assess the role of gC1qR. Additionally, cell growth characteristics were monitored to assess changes in viability and metabolic activity.

RESULTS

Our results indicate that the expression of TF increased significantly after incubation with C1q as compared with unconditioned cells. Cells conditioned with gC1qR blockers and C1q exhibited no change in TF expression when compared with cells conditioned with the blocking antibodies alone. Our results show no significant differences in metabolic activity or cell viability under these conditions.

CONCLUSIONS

This indicates that gC1qR association with C1q induces TF expression and may initiate extrinsic coagulation. Overall, this data illustrates a role for C1q in the activation of extrinsic coagulation and that gC1qR activity may link inflammation and thrombosis.

The complement C3-complement factor D-C3a receptor signalling axis regulates cardiac remodelling in right ventricular failure

Failure of the right ventricle plays a critical role in any type of heart failure. However, the mechanism remains unclear, and there is no specific therapy. Here, we show that the right ventricle predominantly expresses alternative complement pathway-related genes, including Cfd and C3aR1. Complement 3 (C3)-knockout attenuates right ventricular dysfunction and fibrosis in a mouse model of right ventricular failure. C3a is produced from C3 by the C3 convertase complex, which includes the essential component complement factor D (Cfd). Cfd-knockout mice also show attenuation of right ventricular failure. Moreover, the plasma concentration of CFD correlates with the severity of right ventricular failure in patients with chronic right ventricular failure. A C3a receptor (C3aR) antagonist dramatically improves right ventricular dysfunction in mice. In summary, we demonstrate the crucial role of the C3-Cfd-C3aR axis in right ventricular failure and highlight potential therapeutic targets for right ventricular failure.

Right ventricular (RV) failure is clinically crucial, but there is no specific therapy. Here, the authors show that the complement alternative pathway is activated in RV failure and that blockade of the pathway ameliorates RV failure in mice.

Multi-omics of human plasma reveals molecular features of dysregulated inflammation and accelerated aging in schizophrenia

Schizophrenia is a devastating psychiatric illness that detrimentally affects a significant portion of the worldwide population. Aging of schizophrenia patients is associated with reduced longevity, but the potential biological factors associated with aging in this population have not yet been investigated in a global manner. To address this gap in knowledge, the present study assesses proteomics and metabolomics profiles in the plasma of subjects afflicted with schizophrenia compared to non-psychiatric control patients over six decades of life. Global, unbiased analyses of circulating blood plasma can provide knowledge of prominently dysregulated molecular pathways and their association with schizophrenia, as well as features of aging and gender in this disease. The resulting data compiled in this study represent a compendium of molecular changes associated with schizophrenia over the human lifetime. Supporting the clinical finding of schizophrenia's association with more rapid aging, both schizophrenia diagnosis and age significantly influenced the plasma proteome in subjects assayed. Schizophrenia was broadly associated with prominent dysregulation of inflammatory and metabolic system components. Proteome changes demonstrated increased abundance of biomarkers for risk of physiologic comorbidities of schizophrenia, especially in younger individuals. These findings advance our understanding of the molecular etiology of schizophrenia and its associated comorbidities throughout the aging process.

The Alternative Complement Pathway Is Activated Without a Corresponding Terminal Pathway Activation in Patients With Heart Failure

Objective

Dysregulation of the complement system has been described in patients with heart failure (HF). However, data on the alternative pathway are scarce and it is unknown if levels of factor B (FB) and the C3 convertase C3bBbP are elevated in these patients. We hypothesized that plasma levels of FB and C3bBbP would be associated with disease severity and survival in patients with HF.

Methods

We analyzed plasma levels of FB, C3bBbP, and terminal C5b-9 complement complex (TCC) in 343 HF patients and 27 healthy controls.

Results

Compared with controls, patients with HF had elevated levels of circulating FB (1.6-fold, p < 0.001) and C3bBbP (1.3-fold, p < 0.001). In contrast, TCC, reflecting the terminal pathway, was not significantly increased (p = 0.15 vs controls). FB was associated with NT-proBNP, troponin, eGFR, and i.e., C-reactive protein. FB, C3bBbP and TCC were not associated with mortality in HF during a mean follow up of 4.3 years.

Conclusion

Our findings suggest that in patients with HF, the alternative pathway is activated. However, this is not accompanied by activation of the terminal pathway.

Novel biomarkers in cats with congestive heart failure due to primary cardiomyopathy

The pathogenesis of feline cardiomyopathy and congestive heart failure (CHF) requires further understanding. In this study, we assessed serum proteome change in feline CHF, aiming to identify novel biomarker for both research and clinical use. The study comprised 15 cats in CHF, 5 cats in preclinical cardiomyopathy and 15 cats as healthy controls. Serum proteome profiles were obtained by tandem mass tag labelling followed by mass spectrometry. Protein concentrations in CHF cats were compared with healthy controls. Western blot was performed for proteomic validation. Correlations were assessed between the altered proteins in CHF and clinical variables in cats with cardiomyopathy to evaluate protein-cardiac association. Bioinformatic analysis was employed to identify pathophysiological pathways involved in feline CHF. Sixteen serum proteins were significantly different between CHF and healthy control cats (P < .05). These included serine protease inhibitors, apolipoproteins and other proteins associated with inflammation and coagulation. Clinical parameters from cats with cardiomyopathy significantly correlated with the altered proteins (P < .05). Bioinformatic analysis identified 13 most relevant functional profiles in feline CHF, which mostly associated with extracellular matrix organization and metabolism. Data are available via ProteomeXchange with identifier PXD017761. SIGNIFICANCE: Cardiomyopathies affect both cats and humans, and they can cause serious consequence such as congestive heart failure (CHF). To date, the pathophysiological mechanism of CHF is not fully understood. In this study, for the first time, we used a proteomic approach combined with bioinformatic analysis to evaluate serum protein change in cats with CHF. Results indicate systemic inflammation, coagulation protein changes, innate immunity and extracellular matrix remodeling are involved in feline CHF, which are largely comparable with findings in previous human studies. Our study provides new insights into CHF and cardiomyopathy in cats, and the identified novel biomarkers and pathophysiological pathways provide valuable information for future studies.

The role of B cells in heart failure and implications for future immunomodulatory treatment strategies

Despite numerous demonstrations that the immune system is activated in heart failure, negatively affecting patients' outcomes, no definitive treatment strategy exists directed to modulate the immune system. In this review, we present the evidence that B cells contribute to the development of hypertrophy, inflammation, and maladaptive tissue remodelling. B cells produce antibodies that interfere with cardiomyocyte function, which culminates as the result of recruitment and activation of a variety of innate and structural cell populations, including neutrophils, macrophages, fibroblasts, and T cells. As B cells appear as active players in heart failure, we propose here novel immunomodulatory therapeutic strategies that target B cells and their products.

Reappraising the role of inflammation in heart failure

The observation that heart failure with reduced ejection fraction is associated with elevated circulating levels of pro-inflammatory cytokines opened a new area of research that has revealed a potentially important role for the immune system in the pathogenesis of heart failure. However, until the publication in 2019 of the CANTOS trial findings on heart failure outcomes, all attempts to target inflammation in the heart failure setting in phase III clinical trials resulted in neutral effects or worsening of clinical outcomes. This lack of positive results in turn prompted questions on whether inflammation is a cause or consequence of heart failure. This Review summarizes the latest developments in our understanding of the role of the innate and adaptive immune systems in the pathogenesis of heart failure, and highlights the results of phase III clinical trials of therapies targeting inflammatory processes in the heart failure setting, such as anti-inflammatory and immunomodulatory strategies. The most recent of these studies, the CANTOS trial, raises the exciting possibility that, in the foreseeable future, we might be able to identify those patients with heart failure who have a cardio-inflammatory phenotype and will thus benefit from therapies targeting inflammation.

Complement Components sC5b-9 and CH50 Predict Prognosis in Heart Failure Patients Combined With Hypertension

BACKGROUND

Heart failure (HF), resulting from inflammation and vessel injury, is one of the leading causes of poor quality of life and premature death. The complement system plays a leading role in vessel integrity and inflammation response. However, the association between serum complement level and the prognosis of HF remains unclear.

METHODS

In our study, a total of 263 newly diagnosed hypertension patients with HF were included. Eight classical cardiovascular risk factors were collected, and plasma C3a, C3b, C5a, sC5b-9, and CH50 levels were detected.

RESULTS

Compared with the control group, plasma C5a (P<0.001), sC5b-9 (P<0.001), and CH50 (P = 0.004) levels of hypertension patients with HF were significantly increased. On the basis of univariate analysis, an older age, higher frequency of alcohol consumption, high level of body mass index, medium or high risk of hypertension, hyperlipidemia, and diabetes were poor prognostic factors whereas low levels of C5a, sC5b-9, and CH50 were associated with favorable overall survival (OS). When these factors fit into a multivariate regression model, patients with hyperlipidemia (P = 0.002, hazard ratio [HR] = 3.09), N-terminal pro-Brain Natriuretic Peptide (NT-pro-BNP) ≥ 14.8 (P < 0.001, HR = 11.14), sC5b-9 level ≥ 1,406.2 µg/ml (P = 0.180, HR = 5.51) or CH50 level ≥ 294.6 µg/ml (P < 0.001, HR = 4.57) remained statistically factors for worsened OS and regarded as independent risk factors. These independently associated risk factors were used to form an OS estimation nomogram. Nomogram demonstrated good accuracy in estimating the risk, with a bootstrap-corrected C index of 0.789.

CONCLUSIONS

sC5b-9 and CH50 levels are increased in hypertension patients with HF. Nomogram based on multivariate analysis has good accuracy in estimating the risk of OS.

Prolargin and matrix metalloproteinase-2 in heart failure after heart transplantation and their association with haemodynamics

Aims

Remodelling of the extracellular matrix (ECM) is a key mechanism involved in the development and progression of heart failure (HF) but also functional in associated pulmonary hypertension (PH). Our aim was to identify plasma ECM proteins associated to end‐stage HF and secondary PH in relation to haemodynamics, before and after heart transplantation (HT).

Methods and results

Twenty ECM plasma proteins were analysed with proximity extension assay in 20 controls and 26 HF patients pre‐HT and 1 year post‐HT. Right heart catherization haemodynamics were assessed in the patients during the preoperative evaluation and at the 1 year follow‐up post‐HT. Plasma levels of prolargin and matrix metalloproteinase‐2 (MMP‐2) were elevated (P < 0.0001) in HF patients compared with controls and decreased (P < 0.0001) post‐HT towards controls' levels. The decrease in prolargin post‐HT correlated with improved mean right atrial pressure (r_s = 0.63; P = 0.00091), stroke volume index (r_s = −0.73; P < 0.0001), cardiac index (r_s = −0.64; P = 0.00057), left ventricular stroke work index (r_s = −0.49; P = 0.015), and N‐terminal pro brain natriuretic peptide (r_s = 0.7; P < 0.0001). The decrease in MMP‐2 post‐HT correlated with improved mean pulmonary artery pressure (r_s = 0.58; P = 0.0025), mean right atrial pressure (r_s = 0.56; P = 0.0046), pulmonary artery wedge pressure (r_s = 0.48; P = 0.016), and N‐terminal pro brain natriuretic peptide (r_s = 0.56; P = 0.0029).

Conclusions

The normalization pattern in HF patients of plasma prolargin and MMP‐2 post‐HT towards controls' levels and their associations with improved haemodynamics indicate that prolargin and MMP‐2 may reflect, in part, the aberrant ECM remodelling involved in the pathophysiology of HF and associated PH. Their potential clinical use as biomarkers or targets for future therapy in HF and related PH remains to be investigated.

The role of the complement factor B-arginase-polyamine molecular axis in uremia-induced cardiac remodeling in mice

The role of complement system in heart diseases is controversial. Besides, the mechanisms by which complement components participate in cardiac remodeling (CR) and heart failure during uremia are unclear. In this study, 5/6 nephrectomy was performed to adult mice to establish the uremic model and CR deteriorated over the course of uremia. Although complement pathways were not further activated over the course of the disease, soluble complement factor B (CFB) was upregulated at post-nephrectomy day 90 (PNx90) compared with PNx30. Further, CFB notably deteriorated CR in uremic mice but this effect was reversed by depletion of macrophages with liposomal clodronate. In vivo and in vitro CFB upregulated arginase 1 (ARG1) expression, increased ARG1 enzymatic activity, and stimulated the syntheses of ornithine, leading to polyamine overproduction in macrophages. Putrescine, an important polyamine, promoted cardiac fibroblast proliferation and collagen production, resulting in progressive CR. In vivo the inhibition of ARG1 activity with N^ω -hydroxyl-l-arginine remarkably improved the general survival rates, inhibited the infiltration of cardiac fibroblasts, and alleviated progression of CR in uremic mice. Taken together, the CFB-ARG1-putrescine axis is related to progression of CR and ARG1 hyperactivity in macrophages may provide a novel therapeutic target against the heart injury in uremia.

Increased Complement Factor B and Bb Levels Are Associated with Mortality in Patients with Severe Aortic Stenosis

Inflammation is involved in initiation and progression of aortic stenosis (AS). However, the role of the complement system, a crucial component of innate immunity in AS, is unclear. We hypothesized that circulating levels of complement factor B (FB), an important component of the alternative pathway, are upregulated and could predict outcome in patients with severe symptomatic AS. Therefore, plasma levels of FB, Bb, and terminal complement complex were analyzed in three cohorts of patients with severe symptomatic AS and mild-to-moderate or severe asymptomatic AS (population 1, n = 123; population 2, n = 436; population 3, n = 61) and in healthy controls by enzyme immunoassays. Compared with controls, symptomatic AS patients had significantly elevated levels of FB (2.9- and 2.8-fold increase in population 1 and 2, respectively). FB levels in symptomatic and asymptomatic AS patients were comparable (population 2 and 3), and in asymptomatic patients FB correlated inversely with valve area. FB levels in population 1 and 2 correlated with terminal complement complex levels and measures of systemic inflammation (i.e., CRP), cardiac function (i.e., NT-proBNP), and cardiac necrosis (i.e., Troponin T). High FB levels were significantly associated with mortality also after adjusting for clinical and biochemical covariates (hazard ratio 1.37; p = 0.028, population 2). Plasma levels of the Bb fragment showed a similar pattern in relation to mortality. We concluded that elevated levels of FB and Bb are associated with adverse outcome in patients with symptomatic AS. Increased levels of FB in asymptomatic patients suggest the involvement of FB from the early phase of the disease.

Rituximab prevents and reverses cardiac remodeling by depressing B cell function in mice

B lymphocytes have been shown to contribute to autoimmune diseases via producing antibodies and proinflammatory cytokines. Depletion of B cells by blocking CD20 can inhibit these diseases. Here we examined whether an antibody against CD20, rituximab (RTX) (Rituxan^@), used clinically in oncology could have similar anti-inflammatory effects in cardiac remodeling and heart failure (HF) in mice. Cardiac remodeling was established by pressure overload induced by transverse aortic constriction (TAC). Wild-type (WT) male C57BL/6 J mice were subjected to pressure overload by using transverse aortic constriction and then received RTX for 4 weeks. Administration of RTX markedly improves in vivo heart function, and suppressed heart chamber dilation, myocyte hypertrophy, fibrosis and oxidative stress in mice after TAC operation. RTX treatment also reversed established hypertrophic remodeling induced by TAC. Moreover, TAC-induced activation of multiple signaling pathways including calcineurin A, ERK1/2, STAT3, TGFβ/Smad2/3 and IKKα/β/NF-kB were remarkably attenuated in RTX-treated hearts compared with controls. These inhibitory effects of RTX were associated with inhibition of proinflammatory cytokine expression and Th2 cytokine-mediated IgG production from B cells. In conclusion, this study identifies that administration of RTX can inhibit pressure overload-induced cardiac remodeling and dysfunction in mice, and suggest that RTX may be a promising drug for treating hypertrophic disease.

Acute heart failure following myocardial infarction: complement activation correlates with the severity of heart failure in patients developing cardiogenic shock

AIMS

Heart failure (HF) is an impending complication to myocardial infarction. We hypothesized that the degree of complement activation reflects severity of HF following acute myocardial infarction.

METHODS AND RESULTS

The LEAF trial (LEvosimendan in Acute heart Failure following myocardial infarction) evaluating 61 patients developing HF within 48 h after percutaneous coronary intervention-treated ST-elevation myocardial infarction herein underwent a post hoc analysis. Blood samples were drawn from inclusion to Day 5 and at 42 day follow-up, and biomarkers were measured with enzyme immunoassays. Regional myocardial contractility was measured by echocardiography as wall motion score index (WMSI). The cardiogenic shock group (n = 9) was compared with the non-shock group (n = 52). Controls (n = 44) were age-matched and sex-matched healthy individuals. C4bc, C3bc, C3bBbP, and sC5b-9 were elevated in patients at inclusion compared with controls (P < 0.01). The shock group had higher levels compared with the non-shock group for all activation products except C3bBbP (P < 0.05). At Day 42, all products were higher in the shock group (P < 0.05). In the shock group, sC5b-9 correlated significantly with WMSI at baseline (r = 0.68; P = 0.045) and at Day 42 (r = 0.84; P = 0.036). Peak sC5b-9 level correlated strongly with WMSI at Day 42 (r = 0.98; P = 0.005). Circulating endothelial cell activation markers sICAM-1 and sVCAM-1 were higher in the shock group during the acute phase (P < 0.01), and their peak levels correlated with sC5b-9 peak level in the whole HF population (r = 0.32; P = 0.014 and r = 0.30; P = 0.022, respectively).

CONCLUSIONS

Complement activation discriminated cardiogenic shock from non-shock in acute ST-elevation myocardial infarction complicated by HF and correlated with regional contractility and endothelial cell activation, suggesting a pathogenic role of complement in this condition.

The alternative complement pathway is dysregulated in patients with chronic heart failure

The complement system, an important arm of the innate immune system, is activated in heart failure (HF). We hypothesized that HF patients are characterized by an imbalance of alternative amplification loop components; including properdin and complement factor D and the alternative pathway inhibitor factor H. These components and the activation product, terminal complement complex (TCC), were measured in plasma from 188 HF patients and 67 age- and sex- matched healthy controls by enzyme immunoassay. Our main findings were: (i) Compared to controls, patients with HF had significantly increased levels of factor D and TCC, and decreased levels of properdin, particularly patients with advanced clinical disorder (i.e., NYHA functional class IV), (ii) Levels of factor D and properdin in HF patients were correlated with measures of systemic inflammation (i.e., C-reactive protein), neurohormonal deterioration (i.e., Nt-proBNP), cardiac function, and deteriorated diastolic function, (iii) Low levels of factor H and properdin were associated with adverse outcome in univariate analysis and for factor H, this was also seen in an adjusted model. Our results indicate that dysregulation of circulating components of the alternative pathway explain the increased degree of complement activation and is related to disease severity in HF patients.

Complement activation products in acute heart failure: Potential role in pathophysiology, responses to treatment and impacts on long-term survival

Background:

Previous studies have indicated a correlation between heart failure, inflammation and poorer outcome. However, the pathogenesis and role of inflammation in acute heart failure (AHF) is incompletely studied and understood. The aim of our study was to explore the potential role of innate immunity – quantified by complement activation products (CAPs) – in pathophysiology, responses to treatment and impacts on long-term survival in AHF.

Methods:

In a prospective study enrolling 179 unselected patients with AHF, plasma concentrations of C4d, C3a and sC5b-9 were measured in a blinded fashion on the first day of hospitalisation and prior to discharge. The final diagnosis, including the AHF phenotype, was adjudicated by two independent cardiologists. Long-term follow-up was obtained. Findings in AHF were compared to that obtained in 75 healthy blood donors (control group).

Results:

Overall, concentrations of all three CAPs were significantly higher in patients with AHF than in healthy controls (all p < 0.001). In an age-adjusted subgroup analysis, significant differences could be confirmed for concentrations of C4d and sC5b-9, and these parameters further increased after 6 days of in-hospital treatment ( p < 0.001). In contrast, C3a levels in AHF patients did not differ from those of the control group in the age-adjusted subgroup analysis and remained constant during hospitalisation. Concentrations of C4d, C3a and sC5b-9 were significantly higher when AHF was triggered by an infection as compared to other triggers ( p < 0.001). In addition, CAP levels significantly correlated with each other ( r = 0.64–0.76), but did not predict death within 2 years.

Conclusions:

Activation of complement with increased plasma levels of C4d and sC5b-9 at admission and increasing levels during AHF treatment seems to be associated with AHF, particularly when AHF was triggered by an infection. However, CAPs do not have a prognostic value in AHF.

Full Expression of Cardiomyopathy Is Partly Dependent on B-Cells: A Pathway That Involves Cytokine Activation, Immunoglobulin Deposition, and Activation of Apoptosis

BACKGROUND

Limited information exists on the role of B-cell-dependent mechanisms in the progression of heart failure (HF). However, in failing human myocardium, there is evidence of deposition of activated complement components as well as anticardiac antibodies. We aimed to determine the contribution of B-cells in HF progression using a nonsurgical mouse model of nonischemic cardiomyopathy (CMP).

METHODS AND RESULTS

CMP protocol involved the use of l-NAME and NaCl in the drinking water and angiotensin-II infusion for 35 days. At day 35, mice were analyzed by cardiac magnetic resonance imaging, gene expression, and histology. Mice (12 weeks old) were divided into 4 groups, all in C57BL/6 background: wild-type (WT) CMP; severe combined immunodeficiency (SCID) CMP (T- and B-cell deficient); CD22(-) CMP (B-cell depleted); and Nude CMP (T-cell deficient), with their respective controls. We performed B-cell depletion and reconstitution protocols. The protective effect of B-cell depletion was demonstrated by a significant reduction of cell hypertrophy and collagen deposition and a preserved ejection fraction in the CD22(-) CMP group compared to WT CMP. Once SCID mice underwent B-cell reconstitution with isolated CMP B-cells, the CMP phenotype was restored. Furthermore, deposition of IgG3 and apoptosis in the myocardium follows the development of CMP; in addition, in vitro studies demonstrated that activated B-cells stimulate collagen production by cardiac fibroblasts.

CONCLUSIONS

The absence of B-cells in this model of HF resulted in less hypertrophy and collagen deposition, preservation of left ventricular function, and, in association with these changes, a reduction in expression of proinflammatory cytokines, immunoglobulin G deposition, and apoptosis in the myocardium. Taken together, these data suggest that B-cells play a contributory role in an angiotensin-II-induced HF model.

Effect of Cardiac Resynchronization Therapy on Inflammation in Congestive Heart Failure: A Review

Congestive heart failure is associated with increased levels of several inflammatory mediators, and animal studies have shown that infusion of a number of cytokines can induce heart failure. However, several drugs with proven efficacy in heart failure have failed to affect inflammatory mediators, and anti-inflammatory therapy in heart failure patients has thus far been disappointing. Hence, to what extent heart failure is caused by or responsible for the increased inflammatory burden in the patient is still unclear. Over the past couple of decades, resynchronization therapy with a biventricular pacemaker has emerged as an effective treatment in a subset of heart failure patients, reducing both morbidity and mortality. Such treatment has also been shown to affect the inflammation associated with heart failure. In this study, we review recent data on the association between heart failure and inflammation, and in particular how resynchronization therapy can affect the inflammatory process.

A vital role for complement in heart disease

Heart diseases are common and significant contributors to worldwide mortality and morbidity. During recent years complement mediated inflammation has been shown to be an important player in a variety of heart diseases. Despite some negative results from clinical trials using complement inhibitors, emerging evidence points to an association between the complement system and heart diseases. Thus, complement seems to be important in coronary heart disease as well as in heart failure, where several studies underscore the prognostic importance of complement activation. Furthermore, patients with atrial fibrillation often share risk factors both with coronary heart disease and heart failure, and there is some evidence implicating complement activation in atrial fibrillation. Moreover, Chagas heart disease, a protozoal infection, is an important cause of heart failure in Latin America, and the complement system is crucial for the protozoa-host interaction. Thus, complement activation appears to be involved in the pathophysiology of a diverse range of cardiac conditions. Determination of the exact role of complement in the various heart diseases will hopefully help to identify patients that might benefit from therapeutic complement intervention.

Complement C3c as a biomarker in heart failure

Introduction. Experimental data indicates an important role of the innate immune system in cardiac remodeling and heart failure (HF). Complement is a central effector pathway of the innate immune system. Animals lacking parts of the complement system are protected from adverse remodeling. Based on these data, we hypothesized that peripheral complement levels could be a good marker for adverse remodeling and prognosis in patients with HF. Methods and Results. Since complement activation converges on the complement factor C3, we measured serum C3c, a stable C3-conversion product, in 197 patients with stable systolic HF. Subgroups with normal and elevated C3c levels were compared. C3c levels were elevated in 17% of the cohort. Patients with elevated C3c levels exhibited a trend to better survival, slightly higher LVEF, and lower NTpro-BNP values in comparison to patients with normal C3c values. No differences were found regarding NYHA functional class. Significantly more patients with elevated C3c had preexisting diabetes. The prevalence of CAD, arterial hypertension, and atrial fibrillation was not increased in patients with elevated C3c. Conclusion. Elevated C3c levels are associated with less adverse remodeling and improved survival in patients with stable systolic heart failure.

High proportion of patients with end-stage heart failure regardless of aetiology demonstrates anti-cardiac antibody deposition in failing myocardium: humoral activation, a potential contributor of disease progression

AIMS

Various reports have raised the possibility of humoral immune responses as contributors for the progression of heart failure. Previous studies, however, have focused on the analysis of serum and documented circulating antibodies against a variety of cardiac proteins. However, there is little evidence on whether anti-cardiac antibodies are deposited in end-stage failing myocardium. Our objective was to determine whether or not there was evidence of deposition of anti-cardiac antibodies and/or activated complement components in end-stage failing human myocardium.

METHODS AND RESULTS

Myocardial samples were obtained from 100 end-stage heart failure patients and 40 donor control biopsies. Sections were cut and stained using standard fluorescent immunohistochemistry techniques with anti-human immunoglobulin G (IgG), IgG3, and C3c. Gel electrophoresis and protein identification by mass spectrometry were used to confirm the presence of IgG and its antigen. Immunoglobulin G was localized to the sarcolemma in 71% of patients, 48% of those being positive for the subtype IgG3. The proportion of patients with ischaemic heart disease that was positive for IgG was 65% and among those with non-ischaemic aetiologies was 76%. In a subgroup analysis, the presence of IgG and its subunits were confirmed by mass spectrometry and adenosine triphosphate synthase β subunit identified as an antigen. Complement was activated in 31% of all patients. The presence of IgG, IgG3, and C3c was directly correlated with the length of disease (r = 0.451, P = 0.006).

CONCLUSION

Evidence of anti-cardiac antibodies and complement activation was found in a large number of patients with end-stage cardiomyopathy regardless of the aetiology. Adenosine triphosphate synthase appears to be a new prominent antigenic stimulus; but more interestingly, the simultaneous co-existence of activated complement components suggests that this humoral mechanism may participate in disease progression.

Pathological ventricular remodeling: mechanisms: part 1 of 2

Despite declines in heart failure morbidity and mortality with current therapies, rehospitalization rates remain distressingly high, substantially affecting individuals, society, and the economy. As a result, the need for new therapeutic advances and novel medical devices is urgent. Disease-related left ventricular remodeling is a complex process involving cardiac myocyte growth and death, vascular rarefaction, fibrosis, inflammation, and electrophysiological remodeling. Because these events are highly interrelated, targeting a single molecule or process may not be sufficient. Here, we review molecular and cellular mechanisms governing pathological ventricular remodeling.

Association of ficolin-3 with severity and outcome of chronic heart failure

BACKGROUND

Inflammatory mechanisms involving complement activation has been shown to take part in the pathophysiology of congestive heart failure, but the initiating mechanisms are unknown. We hypothesized that the main initiator molecules of the lectin complement pathway mannose-binding lectin (MBL), ficolin-2 and ficolin-3 were related to disease severity and outcome in chronic heart failure.

METHODS AND RESULTS

MBL, ficolin-2 and ficolin-3 plasma concentrations were determined in two consecutive cohorts comprising 190 patients from Hungary and 183 patients from Norway as well as controls. Disease severity and clinical parameters were determined at baseline, and all-cause mortality was registered after 5-years follow-up. In univariate analysis a low level of ficolin-3, but not that of MBL or ficolin-2, was significantly associated with advanced heart failure (New York Heart Association Class IV, p<0.001 for both cohorts) and showed inverse correlation with B- type natriuretic peptide (BNP) levels (r = -0.609, p<0.001 and r = -0.467, p<0.001, respectively). In multivariable Cox regression analysis, adjusted for age, gender and BNP, decreased plasma ficolin-3 was a significant predictor of mortality (HR 1.368, 95% CI 1.052-6.210; and HR 1.426, 95% CI 1.013-2.008, respectively). Low ficolin-3 levels were associated with increased complement activation product C3a and correspondingly decreased concentrations of complement factor C3.

CONCLUSIONS

This study provides evidence for an association of low ficolin-3 levels with advanced heart failure. Concordant results from two cohorts show that low levels of ficolin-3 are associated with advanced heart failure and outcome. The decrease of ficolin-3 was associated with increased complement activation.

Hypertrophic reprogramming of the left ventricle: translation to the ECG

Hypertrophic growth of the heart occurs in many clinical scenarios, and it confers substantially increased risk of untoward sequelae. Among them, transition to ventricular dilation, wall thinning, contractile dysfunction, and a clinical syndrome of heart failure are paramount. Left ventricular hypertrophy (LVH) is typically diagnosed by either electrocardiography or echocardiography. However, these two means of assessing hypertrophic transformation of the left ventricle can sometimes disagree. At one level, this may not be surprising as the two methodologies are based on entirely divergent signals: electrical potential between two places on the surface of the skin and ultrasound energy reflected from the ventricle itself. Echocardiography is an effective means of assessing ventricular mass, which is a cardinal feature of LVH. Importantly, however, LVH is characterized by a wide range of remodeling events beyond simple increases in muscle mass. Electrocardiographic changes in LVH are reflective of the electrophysiological aspects of hypertrophic transformation. Here, I present an overview of the complex biology of left ventricular hypertrophy with an eye toward enhancing our understanding of its ECG manifestations.

Complement anaphylatoxin C3a as a novel independent prognostic marker in heart failure

OBJECTIVES

The purpose of this study was to evaluate complement activation in a heart failure cohort. Based on their powerful biological activity, we hypothesized that the levels of anaphylatoxin C3a are related to pathological signs and outcomes in heart failure.

DESIGN, SETTING AND PATIENTS

Complement activation products C3a and SC5b9 were determined in 182 consecutive CHF patients (single centre, prospective cohort study), with a left ventricular ejection fraction <45%. Mortality and re-hospitalisation due to the progression of CHF were assessed after a median follow-up of 14 months.

INTERVENTIONS

None.

RESULTS

In the univariate analysis, high level of anaphylatoxin C3a was significantly associated with clinical events (p < 0.0001), whereas SC5b9 showed a tendency of association (p = 0.094). In multivariable Cox analysis, adjusted for age, NT-proBNP, diastolic blood pressure, body mass index (BMI), haemoglobin and creatinine levels, C3a was a significant predictor of HF-related re-hospitalization or death (HR 1.189 per 1-SD increase, 95% CI 1.023-1.383), and of cardiovascular events or death (HR 1.302, CI 1.083-1.566). C3a was strongly associated with the presence of peripheral oedema, inflammatory markers (CRP, prealbumin, IL-6, sTNFRI, sTNFRII), heat-shock protein 70 levels and endothelial activation markers (von-Willebrand factor and endothelin-1).

CONCLUSIONS

Results of the present study showed that complement activation is strongly linked to unfavourable outcomes in heart failure. High levels of anaphylatoxin C3a predicted re-hospitalization, cardiovascular events and mortality in adjusted survival model. Increased C3a levels were associated with biomarkers of acute-phase reaction, inflammation, cellular stress response, endothelial-cell activation and oedematous complications independently from disease severity.

The role of monocytes and inflammation in the pathophysiology of heart failure

There is growing evidence to support an important role of inflammation in the underlying pathophysiology of heart failure (HF). Indeed, inflammatory cytokine levels are well recognized to be increased in patients with left ventricular dysfunction and appear to have prognostic implications. Monocytes play a pivotal role in the inflammatory cascade and are a major source of both pro- and anti-inflammatory cytokines. They are intimately involved in tissue damage and repair and an imbalance of these processes may have detrimental consequences for the failing myocardium. Importantly, monocytes comprise of distinct subsets with different cell surface markers and functional characteristics and this heterogeneity may be important in understanding their specific role in HF. In HF, monocyte activation involves interplay between pattern recognition molecules, endotoxins, cytokines, and acute phase proteins. Activated monocytes migrate to the myocardium in response to powerful chemokines, where they must then attach to the endothelial wall before infiltrating into the myocardium itself. This review article aims to discuss the role of monocytes and inflammation in HF, focusing on monocyte activation, mobilisation, recruitment and endothelial adherence, as well as the effects they may have on myocardial performance. The therapeutic modulation of inflammation and monocyte activation in HF treatment will also be reviewed.

Evidence for the use of intravenous immunoglobulins--a review of the literature

Intravenous immunoglobulins (IVIg) were first introduced in the middle of the twentieth century for the treatment of primary immunodeficiencies. In 1981, Paul Imbach noticed an improvement of immune-mediated thrombocytopenia, in patients receiving IVIg for immunodeficiencies. This opened a new era for the treatment of autoimmune conditions with IVIg. Since then, IVIg has become an important treatment option in a wide spectrum of diseases, including autoimmune and acute inflammatory conditions, most of them off-label (not included in the US Food and Drug Administration recommendation). A panel of immunologists and internists with experience in IVIg therapy reviewed the medical literature for published data concerning treatment with IVIg. The quality of evidence was assessed, and a summary of the available relevant literature in each disease was given. To our knowledge, this is the first all-inclusive comprehensive review, developed to assist the clinician when considering the use of IVIg in autoimmune diseases, immune deficiencies, and other conditions.

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

BACKGROUND

Dendritic cells (DCs) are the most potent antigen-presenting cells and play a central role in initiating the primary immune response. Although increasing evidence supports immune-mediated inflammation plays an important role in the pathophysiology of heart failure, little is known regarding the source and mechanism that trigger immune responses. The present study examined whether circulating DCs have any role in the pathophysiology in heart failure in humans.

METHODS AND RESULTS

With multi-color flow cytometry we determined the numbers of circulating myeloid DCs (mDCs) and plasmacytoid DCs (pDCs) in decompensated heart failure patients with NYHA class III or IV on admission (n = 27) and the age-similar control subjects (n = 21). DC activation markers such as CD40, and CCR7 were also measured. On admission, circulating mDC and pDC counts were significantly lower in decompensated heart failure patients compared to control subjects (p < 0.01). Circulating mDCs and pDCs were activated in the decompensated heart failure patients. Heart failure treatment restored the reduction and the activation of circulating mDCs and pDCs (p < 0.05). The increases of circulating DCs numbers after treatment were correlated with the decreases in B-type natriuretic peptide (BNP) and troponin-T (p < 0.05) and with the increase in left ventricular ejection fraction (LVEF) (p < 0.01). Furthermore, we found that poor recovery of the circulating DCs number after treatment predicted recurrence of decompensated heart failure.

CONCLUSION

These findings suggest that the reduction and activation of circulating DCs may be involved in the pathophysiology of heart failure.

Depletion of the C3 component of complement enhances the ability of rituximab-coated target cells to activate human NK cells and improves the efficacy of monoclonal antibody therapy in an in vivo model

Growing evidence indicates antibody-dependent cellular cytotoxicity (ADCC) contributes to the clinical response to monoclonal antibody (mAb) therapy of lymphoma. Recent in vitro analysis suggests C3b can inhibit mAb-induced natural killer (NK)-cell activation and ADCC. Further studies were conducted to assess the effect of C3 depletion on mAb-induced NK activation and therapy of lymphoma. Normal human serum inhibited the ability of rituximab-coated lymphoma cells to activate NK cells as previously reported. Serum did not inhibit NK-cell activation when it was preincubated with cobra venom factor (CVF) to deplete C3. Similar results were found when transudative pleural fluid or nonmalignant ascites was used as surrogates for extravascular fluid, suggesting the inhibitory effect of complement may be present in the extravascular compartment, in which many malignant lymphocytes reside. In vivo, C3 was depleted before mAb treatment in a syngeneic murine model of lymphoma. Survival of lymphoma-bearing mice after treatment with CVF plus mAb and with a human C3 derivative with CVF-like functions (HC3-1496) plus mAb was both superior to that of mAb alone. These studies show that complement depletion enhances NK-cell activation induced by rituximab-coated target cells and improves the efficacy of mAb therapy in a murine lymphoma model.

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.

Successful split liver-kidney transplant for factor H associated hemolytic uremic syndrome

BACKGROUND AND OBJECTIVES

A male infant with a family history of thrombotic microangiopathy developed atypical hemolytic uremic syndrome (aHUS).

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Case report.

RESULTS

Genetic analysis demonstrated a heterozygous mutation (S1191L) of CFH, the gene coding complement factor H (CFH). The child suffered many episodes of HUS, each treated with plasma exchange. In time, despite initiation of a prophylactic regimen of plasma exchange, his renal function declined significantly. At the age of 4 yr he received a (split liver) combined liver-kidney transplant (LKT) with preoperative plasma exchange and enoxaparin anticoagulation. Initial function of both grafts was excellent and is maintained for nearly 2 yr.

CONCLUSIONS

This report adds to the small but growing number of individuals in whom LKT has provided a favorable outcome for aHUS associated with CFH mutation, expands the technique of using a split liver graft, and describes the unique histologic features of subclinical liver disease in HUS.

Cytokine Activation and Disease Progression in Patients With Stable Moderate Chronic Heart Failure

BACKGROUND

Activation of the cytokine and the complement system is associated with disease progression in severe congestive heart failure (CHF). Magnitude and prognostic relevance of cytokine and complement activation remain uncertain in patients with moderate CHF.

OBJECTIVES

Measurement of cytokine and complement activation in patients with moderate CHF and testing whether C-reactive protein (CRP) can serve as a surrogate marker of their activation, adding independent prognostic information when co-measured with B-type natriuretic peptide (BNP).

METHODS

The 118 study participants were separated into three groups based on pre-determined CRP and BNP levels: Group I (n = 27; CRP > 5 mg/liter, BNP > or = 200 pg/ml); Group II (n = 46; CRP < or = 5 mg/liter, BNP > or = 200 pg/ml); and Group III (n = 45; CRP < or = 5 mg/liter, BNP < 200 pg/ml).

RESULTS

Mortality was high in Group I (30%; log-rank p < 0.001) but low in Groups II and III (2% and 4%, respectively; log rank, p = 0.7). No differences were observed for left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter (LVEDD) between Groups I and II (31 +/- 16 vs 32 +/- 14% and 66 +/- 16 vs 65 +/- 11 mm, respectively), whereas in Group III LVEF was higher (42 +/- 17%, p = 0.002) with smaller LVEDD (57 +/- 13 mm, p = 0.012). Cytokine sCD14 and tumor necrosis factor (TNF)-alpha levels were not different between the three groups. However, interleukin-6 levels (9.75 +/- 8.17 pg/ml, p = 0.001) and the terminal complement complex C5b-9 (109.9 +/- 68 ng/ml; p = 0.04) were elevated in Group I, both correlating with CRP (interleukin-6: r = 0.5, p < 0.001; C5b-9: r = 0.41, p = 0.001).

CONCLUSIONS

CRP may be used as a surrogate parameter for interleukin-6 and complement activation in moderate CHF. CRP in combination with BNP identifies a high-risk group with a tendency for poor outcome not discriminated by cardiac function.

Activation of immune and inflammatory systems in chronic heart failure: novel therapeutic approaches

Despite extensive research and novel treatments, chronic heart failure (CHF) remains a cause of high morbidity and mortality. Mounting evidence suggested that immune activation and inflammation play critical roles in the pathogenesis of CHF. In this review, we examine the current evidence regarding this contemporary pathophysiological mechanism, and evaluate the effects of conventional and novel cardiovascular drugs, such as calcium sensitisers and statins, on the immune and inflammatory mediator's network. Although therapies, which specifically antagonise tumour necrosis factor-alpha have not demonstrated considerable benefit in patients with CHF, there is an increasing evidence to suggest greater value from non-specific anti-inflammatory approaches, including: pentoxifylline, intravenous immunoglobulin, immune modulation therapy, growth hormones, physical training and nutrition regulation. Several innovative therapeutic targets, such as peroxisome proliferator-activated receptor gamma activators, Rho-kinase, p38 mitogen-activated protein kinase, nuclear transcription factor NF-kappaB, recovering or augmenting parasympathetic tone, cardiac resynchronisation therapy, macrophage inhibitors and chemokine receptor antagonists, are briefly discussed in this review. While we have recently demonstrated the potential merits of combining low-dose methotrexate with conventional therapy, through extensively modulating the activated immune and inflammatory mediator's network, there is a need for further rigorous research of this complex network, especially involving current promising therapies which modulate this system. Such evidence has the potential to revolutionise changes for the management of this disorder. Based on the 'heterogeneity' of immune activation and inflammation among different CHF populations, an 'optimised combination treatment' may offer exciting benefits for individual therapy in the future.

The role of intravenous immunoglobulin in the treatment of chronic heart failure

Chronic heart failure (HF), including both ischemic and idiopathic dilated cardiomyopathies, is accompanied by a dysregulated cytokine network characterized not only by a rise in inflammatory cytokines, but also by an inadequate elevation of anti-inflammatory mediators. This dysregulation has been implicated in the development and progression of chronic HF, and in the last decade, attempts have been made to modulate this persistent inflammation. Failure of anti-tumor necrosis factor therapy in HF has led to further interest in a more general immunomodulatory approach, directed against the inflammatory imbalance rather than one particular cytokine. Treatment with intravenous immunoglobulin (IVIg) may represent such a broad-based approach trying to restore the dysregulated cytokine network through various mechanisms such as Fc receptor blockade, neutralization of microbial antigens and superantigens and more direct anti-inflammatory effects on the cytokine network. However, although one randomized placebo-controlled study in patients with chronic HF showed that IVIg improved left ventricular ejection fraction, accompanied by anti-inflammatory net effects, IVIg had no effect in another placebo-controlled study examining the effect of this medication in recent-onset cardiomyopathy. So far, few patients have been included in clinical trials, and there is clearly a need for larger placebo-controlled mortality studies involving a diverse group of patients with regard to cause and severity of HF.

Anti-Inflammatory Effect of Cardiac Resynchronization Therapy

BACKGROUND

Congestive heart failure (CHF) is associated with persistent immune activation. Medical therapy has been shown to exert only limited anti-inflammatory effects. Cardiac resynchronization therapy (CRT) reduces morbidity and mortality in a subset of patients with heart failure, but it is not known whether this treatment affects the immune system as well. To test this hypothesis, eight patients with heart failure scheduled for CRT were investigated for immune activation before and 6 months after CRT treatment.

METHODS AND RESULTS

After 6 months, all patients had improved in NYHA-class and LVEF, and there was a statistically significant reduction in serum N-terminal pro brain natriuretic peptide (BNP). Furthermore, there was a statistically significant reduction in plasma levels of the chemokines monocyte chemoattractant protein 1 (MCP-1) and interleukin 8 (IL-8) and the cytokine interleukin 6 (IL-6). We observed no changes in the levels of interleukin 1beta (IL-1beta), tumor necrosis factor alpha (TNF-alpha), interleukin 10 (IL-10), or complement activation products. There was a significant correlation between changes in BNP and IL-6 (r = 0.74, P = 0.037).

CONCLUSION

Although based upon a limited number of patients, this report indicates that CRT reduces peripheral markers of immune activation in patients with CHF. Further large scale studies are warranted to verify these findings.

Free radicals in blood: Evolving concepts in the mechanism of ischemic heart disease

There has been a considerable debate over past decade on how reactive oxidant species (ROS) in blood augment the cell signaling processes involved in the pathogenesis of coronary heart disease. In particular, it is not clear whether ROS is an important component of the cross-talk between blood and elements of the vasculature during the initial and latter stages of vascular injury and development of atherosclerotic lesions. Features like the recruitment of the circulating activated monocytes, T cells and granulocytes occur extensively in patients with acute coronary syndromes. It is not known what drives the infiltration of these cells into the vessel wall in the active stages of atherosclerosis and whether ROS plays an intermediate part. Currently, the thinking is that although inflammatory processes may be prompted by different etiological factors from that of coronary heart disease, the presence of ROS in circulating blood is the key intermediary related to vascular injury and organ dysfunction. We review, the clinical and experimental data of the mechanisms involved, and evaluate the wider implications of this concept.

Inflammatory Response and Re-stenosis After Percutaneous Coronary Intervention in Heart Transplant Recipients and Patients With Native Atherosclerosis

BACKGROUND

The clinical benefit of percutaneous coronary intervention (PCI) in heart transplant recipients (HTRs) with coronary allograft vasculopathy (CAV) has been questioned. We investigated the degree of inflammatory reaction during PCI in CAV compared to patients with native atherosclerosis, and the possible relationship between PCI-induced inflammation and the degree of re-stenosis in these 2 patient groups.

METHODS

In 11 CAV patients and 10 patients with native atherosclerosis, blood samples were drawn before and 24 hours and 6 months after PCI, and analyzed with regard to hsCRP, MCP-1, components of complement activation, von Willebrand factor (vWf), soluble L-selectin and ICAM-1. Quantitative angiography was performed before and after PCI, and at 6-month follow-up.

RESULTS

Baseline levels of hsCRP, vWf and MCP-1 were significantly elevated and levels of L-selectin and ICAM-1 and activation products of the alternative pathway of the complement system were decreased in CAV patients compared to those with native atherosclerosis. PCI induced significant increases of hsCRP in both groups as well as an increase in vWf in native atherosclerosis, whereas a decrease in L-selectin was observed in native atherosclerosis. Plasma levels of MCP-1 correlated with percent stenosis at follow-up in both groups, whereas a correlation between hsCRP and percent stenosis was evident only in patients with native atherosclerosis. There were no differences in rates of re-stenosis between the 2 groups.

CONCLUSIONS

HTRs with CAV and patients with native atherosclerosis are characterized by different profiles of immune activation and respond differently to PCI. Nevertheless, an inappropriate inflammatory reactivity may predispose to re-stenosis after PCI in both groups of patients, with pre-procedural inflammation being of particular importance in CAV.

Review of trials in chronic heart failure showing broad-spectrum anti-inflammatory approaches

Accumulating evidence indicates that inflammatory mediators are important in the pathogenesis of chronic heart failure (CHF), contributing to cardiac remodeling and peripheral vascular disturbances. Several studies have shown increased levels of inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, and IL-6 in patients with CHF in both plasma and circulating leukocytes as well as in the failing myocardium itself. Importantly, this increase in inflammatory mediators does not seem to be accompanied by a corresponding increase in anti-inflammatory cytokines, such as IL-10 and transforming growth factor-beta, resulting in an inflammatory imbalance in the cytokine network. Traditional cardiovascular drugs seem to have little influence on the cytokine network in patients with CHF, and immunomodulatory therapy in addition to "optimal" cardiovascular treatment regimens has emerged as an option. Thus, several animal studies as well as some clinical pilot trials have suggested that downregulation of inflammatory cytokines may improve cardiac performance. On the other hand, preliminary results from placebo-controlled anti-TNF studies suggest no effect, or even an adverse effect of anti-TNF therapy on mortality and hospitalization. Although somewhat disappointing, these negative results do not necessarily argue against the cytokine hypothesis. These studies only underscore the difficulties and challenges in developing treatment modalities that can modulate the cytokine network in patients with CHF, resulting in anti-inflammatory and beneficial net effects. Further research in this area will have to more precisely identify the most important "actors" in the immunopathogenesis of CHF to improve the immunomodulatory treatment regimens in this disorder.

Agents targeting inflammation in heart failure

Evidence from both experimental and clinical trials indicates that inflammatory mediators are important in the pathogenesis of chronic heart failure (HF), contributing to cardiac remodelling and peripheral vascular disturbances. Several studies have shown raised levels of inflammatory cytokines such as TNF-alpha, IL-1beta and -6 in HF patients in plasma, circulating leukocytes, atherosclerotic lesions, and in the failing myocardium itself. Importantly, this rise in inflammatory mediators does not seem to be accompanied by a corresponding increase in anti-inflammatory cytokines such as IL-10 and transforming growth factor-beta; thus resulting in an inflammatory imbalance in the cytokine network. Traditional cardiovascular drugs have little influence on the cytokine network in HF patients. Results from randomised, placebo-controlled anti-TNF studies suggest lack of effect of such therapy. Although somewhat disappointing, these negative results do not necessarily argue against the 'cytokine hypothesis'; these studies just underscore the challenges in understanding the complex cytokine network in order to develop effective treatment modalities in HF patients. More general immunmodulating treatments, such as pentoxyfylline, intravenous immunoglobulin, thalidomide and statins, have shown promising results in smaller studies, which need to be confirmed in larger studies with hospitalisations and death as the end points. In addition, further research in this area will have to be more precise in identifying the most important 'actors' in the immunopathogenesis of chronic HF.

Low mannose-binding lectin and increased complement activation correlate to allograft vasculopathy, ischaemia, and rejection after human heart transplantation

AIMS

Transplant-associated coronary artery disease (TxCAD) is a major cause of post-transplant graft failure. The aim of this study was to investigate a possible role of mannose-binding lectin (MBL) deficiency and complement activation in TxCAD.

METHODS AND RESULTS

In a prospective study of heart transplant recipients (n=38) with a follow-up of 5.3+/-1.3 years (range: 0.9-6.6), angiographically verified TxCAD (n=6) was correlated to plasma MBL, complement activation, and endothelial activation (soluble E-selectin). MBL deficiency (<100 ng/mL) was detected in 3/6 patients with TxCAD and in 3/32 with non-TxCAD (Kaplan-Meier, P=0.020). Furthermore, one or more acute rejection episodes were observed in 6/6 of the MBL-deficient patients and in 15/32 of the MBL-sufficient patients (chi(2); P=0.016). Complement activation (C4bc) correlated with soluble E-selectin (r=0.36; P=0.027), both being significantly higher in patients with ischaemia detected in the first biopsy (C4bc: 13.4+/-6.1 AU/mL; E-selectin: 96+/-13 ng/mL) than in those without ischaemia (C4bc: 6.3+/-0.5; E-selectin: 51+/-6; P=0.037 and 0.002). Finally, terminal complement complex correlated closely with mortality (P=0.002).

CONCLUSION

Low MBL was related to the development of TxCAD and acute rejection and increased complement activation correlated to histopathologic ischaemia and mortality after heart transplantation.

Targets for immunomodulation in cardiovascular disease – where are we now?

The recognition that inflammation plays an important role in most cardiovascular pathologies offers the potential for the development of new therapeutic targets. Heart failure and in-stent restenosis are two areas in which there have been very recent developments in identifying and targeting potential inflammatory mediators. The development of both broad anti-inflammatory strategies and more targeted approaches have confirmed that immunomodulation may have a beneficial effect on disease progression of restenosis and heart failure in experimental animals, while the results from clinical studies highlight the need to consider the inflammatory processes as a whole, rather than some aspects in isolation. This review briefly summarizes the key stimuli for initiating inflammation in cardiovascular disease, recent clinical and experimental developments in the search for appropriate anti-inflammatory strategies and considers the possible pitfalls and future challenges for developing this area.