Elevated circulating levels of beta 2-microglobulin in patients with idiopathic dilated cardiomyopathy

Multiplexed MRM-Based Proteomics Identified Multiple Biomarkers of Disease Severity in Human Heart Failure

Heart failure (HF) is a complex disease due to the intricate interplay of several mechanisms, which therefore implies the need for a multimarker strategy to better personalize the care of patients with HF. In this study, we developed a targeted mass spectrometry approach based on multiple reaction monitoring (MRM) to measure multiple circulating protein biomarkers, involved in cardiovascular disease, to address their relevance in the human HF, intending to assess the feasibility of the workflow in the disease monitoring and risk stratification. In this study, we analyzed a total of 60 plasma proteins in 30 plasma samples from eight control subjects and 22 age- and gender- matched HF patients. We identified a panel of four plasma proteins, namely Neuropilin-2, Beta 2 microglobulin, alpha-1-antichymotrypsin, and complement component C9, that were more abundant in HF patients in relation to disease severity and pulmonary dysfunction. Moreover, we showed the ability of the combination of these candidate proteins to discriminate, with sufficient accuracy, HF patients from healthy subjects. In conclusion, we demonstrated the feasibility and potential of a proteomic workflow based on MRM mass spectrometry for the evaluation of multiple proteins in human plasma and the identification of a panel of biomarkers of HF severity.

Association Between Serum β2 -Microglobulin Levels and Prevalent and Incident Physical Frailty in Community-Dwelling Older Women

OBJECTIVES

To investigate whether higher serum β₂ -microglobulin (B2M) levels, a kidney function marker, are associated with prevalent and incident frailty in community-dwelling older women.

DESIGN

Cross-sectional and longitudinal analyses of a prospective cohort.

SETTING

Population-based cohort study in Tokyo, Japan.

PARTICIPANTS

Community-dwelling women aged 75 and older with adequate data for assessing frailty status (N = 1,191) and a subset of participants without baseline frailty but with repeated frailty assessment at 2 and 4 years of follow-up.

MEASUREMENTS

The primary predictor was B2M level. Outcomes were prevalent and incident frailty during the 4-year follow-up period. Frailty was defined as presence of three of the five Fried criteria: weight loss, exhaustion, weakness, slowness, and low physical activity. Adjusted odds ratios for the main confounders were obtained using logistic regression. Discrete-time Cox proportional hazards models were used to determine the risk of developing frailty.

RESULTS

The study included 241 (20.2%) women with prevalent frailty at baseline and 139 (21.1%) with incident frailty during the 4-year follow-up. On multivariate analysis adjusted for multiple potential confounders, the odds of prevalent frailty were 2.5 times as great with B2M levels of 1.9 to 2.1 mg/L as with levels less than 1.6 mg/L and 2.0 times as great with B2M levels of 2.2 mg/L or more. In the unadjusted model, B2M levels of 1.9 to 2.1 mg/L were associated with a greater incidence of frailty than B2M levels of less than 1.6 mg/L (hazard ratio = 1.72, 95% confidence interval = 1.04-2.86). In the multivariate analysis adjusted for potential confounders, no significant association was noted between the highest B2M quartile and incident frailty.

CONCLUSION

Higher B2M levels were independently associated with greater frailty at baseline in older adults but only slightly associated with greater risk of incident frailty over 4 years of follow-up.

Neopterin and beta-2 microglobulin relations to immunity and inflammatory status in nonischemic dilated cardiomyopathy patients

BACKGROUND

The aim of the study was to assess the relationships among serum neopterin (NPT), β2-microglobulin (β2-M) levels, clinical status, and endomyocardial biopsy results of dilated cardiomyopathy patients (DCM).

METHODS

Serum NPT and β-2 M were determined in 172 nonischaemic DCM patients who underwent right ventricular endomyocardial biopsy and 30 healthy subjects (ELISA test). The cryostat biopsy specimens were assessed using histology, immunohistology, and immunochemistry methods (HLA ABC, HLA DR expression, CD3 + lymphocytes, and macrophages counts).

RESULTS

The strong increase of HLA ABC or HLA DR expression was detected in 27.2% patients-group A-being low in 72.8% patients-group B. Neopterin level was increased in patients in group A compared to healthy controls 8.11 (4.50-12.57) versus 4.99 (2.66-8.28) nmol/L (P < 0.05). β-2 microglobulin level was higher in DCM groups A (2.60 (1.71-3.58)) and B (2.52 (1.51-3.72)) than in the control group 1.75 (1.28-1.96) mg/L, P < 0.001. Neopterin correlated positively with the number of macrophages in biopsy specimens (P < 0.05) acute phase proteins: C-reactive proteins (P < 0.05); fibrinogen (P < 0.01); and NYHA functional class (P < 0.05) and negatively with left ventricular ejection fraction (P < 0.05).

CONCLUSIONS

Neopterin but not β-2 microglobulin concentration reflected immune response in biopsy specimens. Neopterin correlated with acute phase proteins and stage of heart failure and may indicate a general immune and inflammatory activation in heart failure.

Beta 2 microglobulin and the risk for cardiovascular events in patients with asymptomatic carotid atherosclerosis

BACKGROUND AND PURPOSE

Atherosclerosis is a chronic inflammatory disease. Ongoing inflammation is associated with elevated levels of beta 2 microglobulin (B2M). We investigated B2M levels in a large cohort of patients with carotid atherosclerosis for the occurrence of major adverse cardiovascular events.

METHODS

One thousand five of 1286 consecutive, neurologically asymptomatic patients with carotid atherosclerosis were followed for a median of 3 years (interquartile range, 2.5 to 3.5) for the occurrence of major adverse cardiovascular events, a composite of myocardial infarction, percutaneous coronary intervention, coronary bypass graft, stroke, and death.

RESULTS

We recorded 359 major cardiovascular events in 271 (27%) patients. B2M was significantly associated with the occurrence of major adverse cardiovascular events. With increasing quartiles of B2M, the adjusted hazard ratios were 1.19 (95% CI, 0.81 to 1.73), 1.51 (95% CI, 1.05 to 2.18), and 1.88 (95% CI, 1.26 to 2.79) compared with the lowest quartile, respectively (P<0.001). Adjusted hazard ratios for the occurrence of death, myocardial infarction, and stroke for increasing quartiles of B2M were 1.25 (95% CI, 0.92 to 1.70), 1.52 (95% CI, 1.12 to 2.06), and 1.62 (95% CI, 1.16 to 2.67) compared with the lowest quartile, respectively (P<0.001). Through statistical estimation of improvement in risk stratification, addition of B2M to baseline risk factors improved the risk stratification for major cardiovascular events, at least as much as high-sensitivity C-reactive protein or even better.

CONCLUSIONS

B2M was independently and significantly associated with adverse cardiovascular outcome in patients with prevalent asymptomatic carotid atherosclerosis.

Improvement of cardiac function after immunoadsorption in patients with dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is a myocardial disease characterized by progressive depression of myocardial contractile function and by ventricular dilatation. Abnormalities of the cellular and humoral immune system are present in patients with myocarditis and DCM. Various circulating cardiac autoantibodies have been detected among patients suffering from DCM. The relative contribution of cardiac antibodies to cardiac malfunction in DCM remains to be elucidated. Extraction of antibodies by immunoadsorption has been successfully used for treatment of various autoimmune diseases. In this review we report recent studies, which indicate that immunoadsorption improves cardiac function of patients with DCM. The data from these studies indicate that activation of the humoral immune system, with production of cardiac autoantibodies, may play a functional role in cardiac malfunction of patients with DCM.

Removal of cardiodepressant antibodies in dilated cardiomyopathy by immunoadsorption

OBJECTIVES

The objective of this study was to investigate whether immunoadsorption (IA) removes cardiodepressant antibodies from the plasma of patients with dilated cardiomyopathy (DCM), as well as to describe their effects on isolated rat cardiomyocytes.

BACKGROUND

Immunoadsorption induces early hemodynamic improvement in patients with DCM. The mechanisms for this improvement remain to be elucidated.

METHODS

Patients with DCM (n = 11; left ventricular ejection fraction < 30%, cardiac index [CI] < 2.5 l/min per m(2)) were treated with IA on three consecutive days, with one IA session daily, by application of specific antibody columns directed against human immunoglobulin (Ig). Immunoadsorption was also conducted on 500 ml of blood taken from nine healthy donors (control subjects). After passage of plasma, the IA columns were regenerated. Column eluent (CE) was collected and dialyzed (100 kD). Confocal laser scanning microscopy was used to analyze the effects of CE on cell contraction and on Ca(2+)-dependent fluorescence in isolated, field-stimulated adult rat cardiomyocytes loaded with cell-permeable Fluo-3. Immunoprecipitation with different preparations of myocardial protein fractions was used for characterization of cardiotropic antibodies.

RESULTS

During IA, the IgG plasma level decreased from 10.7 +/- 0.6 to 2.4 +/- 0.1 g/l (mean +/- SEM), and the CI increased from 2.2 +/- 0.1 to 2.7 +/- 0.2 l/min per m(2) (p < 0.01). The CE obtained from control subjects did not influence Ca(2+) transients or cell shortening of cardiomyocytes. In contrast, in patients with DCM, the CE collected during the first regeneration cycle of the first IA session caused an immediate and dose-related decrease of Ca(2+) transients (dilution 1:5; -22.7 +/- 5.5%; p < 0.01) and cell shortening (dilution 1:5; -29.9 +/- 6.0%, p < 0.01). Early hemodynamic improvement among the patients correlated with the cardiodepressant effect of CE on the isolated cardiomyocytes. Purification of CE by protein A adsorption indicated that the cardiodepressant substances are antibodies. Immunoprecipitation revealed that the eliminated antibodies are capable of binding to various myocardial proteins.

CONCLUSIONS

Cardiac autoantibodies play a functional role in DCM, and their removal may induce early hemodynamic improvement.

Immunohistological changes in dilated cardiomyopathy induced by immunoadsorption therapy and subsequent immunoglobulin substitution

BACKGROUND

Immunoadsorption (IA) and subsequent immunoglobulin (Ig) G substitution represent an additional therapeutic approach in dilated cardiomyopathy (DCM). It remains to be elucidated whether this treatment modulates myocardial inflammation, which is possibly a causal factor of ventricular dysfunction.

METHODS AND RESULTS

From 25 DCM patients (EF <30%), 12 patients were randomized for IA therapy and subsequent IgG substitution at 1-month intervals until month 3. Before (<7 days) and after IA therapy, right ventricular biopsies were obtained from all patients. Biopsies were also obtained at intervals of 3 months from 13 patients without IA/IgG treatment (controls). IA/IgG treatment induced improvement in left ventricular ejection fraction from 21.3+/-1.7% (+/-SEM) to 27.0+/-1.3% (P<0.01 versus baseline/controls) and reduction of the beta-receptor autoantibody serum levels (P<0.01 versus baseline/controls). The number of CD3 cells decreased from 5.7+/-0.8 to 2.9+/-0.5 cells/mm(2) (P<0.01 versus baseline/controls). This decline was paralleled by a decrease in CD4 (P<0.01 versus baseline/controls) and CD8 (P<0.05 versus baseline/controls) lymphocytes. The number of leukocyte common antigen-positive cells (leukocytes) was reduced from 20.0+/-3.2 to 9.9+/-2.8 cells/mm(2) (P<0.01 versus baseline/P<0.05 versus controls). HLA class II expression decreased from 2.1+/-0.7% to 1.1+/-0.4% (P<0.05 versus controls/baseline). The number of immunopositive cells and the expression of HLA class II in controls remained stable. In both groups, the degree of fibrosis remained unchanged.

CONCLUSIONS

IA and subsequent IgG substitution mitigate myocardial inflammation in DCM.

Elevated serum levels of soluble interleukin-2 receptor, neopterin and beta-2-microglobulin in idiopathic dilated cardiomyopathy: relation to disease severity and autoimmune pathogenesis

BACKGROUND

It has not been assessed whether high levels of soluble interleukin 2 receptor (sIL-2R), neopterin and beta-2 microglobulin in idiopathic dilated cardiomyopathy reflect heart failure severity and/or an active autoimmune process. The aim of this study was to relate serum levels of these markers to clinical and autoimmune features.

METHODS

We studied 60 patients with idiopathic dilated cardiomyopathy, 67 controls with ischemic heart failure and 34 normals.

RESULTS

Abnormal levels of sIL-2R, but not of neopterin and beta-2 microglobulin, were more frequent in idiopathic dilated cardiomyopathy than in ischemic patients (35% vs. 16%; P=0.02) or in normals (35% vs. 12%, P=0.01); mean sIL-2R levels were, however, similar in idiopathic dilated cardiomyopathy and ischemic heart failure (842+/-75 vs. 762+/-93 U/ml, P=NS). In idiopathic dilated cardiomyopathy abnormal levels of sIL-2R were associated with lower peak oxygen consumption (P=0.008), higher neopterin and HLA class II expression in the myocardium (P=0.02), but were unrelated to cardiac autoantibody status or titer. In addition, abnormal levels of neopterin were associated with adverse prognosis and higher beta-2 microglobulin; abnormal levels of beta-2 microglobulin with lower echocardiographic percent fractional shortening, higher sIL-2R and higher neopterin.

CONCLUSIONS

There is no convincing evidence that abnormal sIL-2R, neopterin and/or beta-2 microglobulin are disease-specific markers of idiopathic dilated cardiomyopathy. The lack of association with cardiac autoantibodies suggests that these abnormalities are mainly related to heart failure severity rather than autoimmune pathogenesis. In keeping with this view, high levels of sIL-2R, neopterin and/or beta-2 microglobulin identified a subset of idiopathic dilated cardiomyopathy patients with advanced disease and poor prognosis.

Cytokine network in congestive heart failure secondary to ischemic or idiopathic dilated cardiomyopathy

Inflammatory cytokines may play a pathogenic role in the development of congestive heart failure (CHF). Elevated circulating levels of inflammatory cytokines have been reported in CHF, but most studies have focused on only a few cytokine parameters. However, the activity of these cytokines are modulated by soluble cytokine receptors and cytokines with anti-inflammatory activities, and in the present study several of these interacting factors were examined simultaneously in 38 CHF patients with various degrees of heart failure and in 21 healthy controls. Patients with CHF had increased plasma concentrations of tumor necrosis factor (TNF)alpha, interleukin-6, soluble TNF receptors and the soluble interleukin-6 receptor, glycoprotein (gp)130. They also had elevated ratios of TNFalpha/soluble TNF receptors and interleukin-6/soluble gp130 as well as enhanced interleukin-6 bioactivity in serum, suggesting inflammatory net effects. In addition to raised circulating levels of inflammatory cytokines, CHF patients with severe heart failure also had abnormalities in the levels of anti-inflammatory cytokines, with decreased levels of transforming growth factor beta1 and inadequately raised interleukin-10 in relation to the elevated TNFalpha concentrations. This dysbalance between inflammatory and anti-inflammatory cytokines was also found in monocyte supernatants from CHF patients. The abnormalities in the cytokine network were most pronounced in patients with the most severe heart failure, and several of the immunologic parameters, in particular soluble gp130, were correlated with variables reflecting deranged hemodynamic status. The present study analyzing the complexity of the cytokine network in CHF, demonstrates profound disturbances in the levels of both inflammatory and anti-inflammatory mediators with a marked dysbalance favoring inflammatory effects.

Soluble interleukin-2 receptor levels in patients with dilated cardiomyopathy. Correlation with disease severity and cardiac autoantibodies

BACKGROUND

There is evidence that autoimmunity plays an important role in the initiation and progression of myocardial injury in dilated cardiomyopathy. Abnormalities of both cellular and humoral immunity have been described in this disease. Soluble interleukin-2 receptor (sIL-2R) levels in the serum reflect activation of T lymphocytes in the periphery or in tissues. The present study explored the possibility that activation of cellular immunity is frequent in patients with idiopathic dilated cardiomyopathy and may have functional consequences.

METHODS AND RESULTS

Serum sIL-2R levels were determined with an enzyme-linked immunosorbent assay in 50 dilated cardiomyopathy patients, 30 patients with ischemic heart disease, and 22 normal control subjects. In addition, the presence of anti-beta-receptor and antimyosin antibodies was sought in the serum of cardiomyopathy patients. High sIL-2R levels (> 1400 pg/mL) were found in 38% of the dilated cardiomyopathy patients but only 6% of the ischemic heart disease patients. The group of sIL-2R-positive patients was characterized by higher average age, a higher percentage of women, and more severe disease (lower ejection fraction, higher left ventricular filling pressures, and lower cardiac output). Although the prevalence of cardiac autoantibodies did not correlate with the presence of high sIL-2R levels, higher titers of autoantibodies were found predominantly in the sIL-2R-positive group.

CONCLUSIONS

T-lymphocyte activation, as reflected in elevated sIL-2R levels, is frequent in patients with dilated cardiomyopathy and is associated with more severe disease. Cellular and humoral immune activation may correlate with progression of the disease process.

Endomyocardial HLA expression is increased to the same extent in idiopathic and secondary dilated cardiomyopathy

In a total of 22 failing hearts from human transplant recipients, the expression of major histocompatibility complex (MHC) molecules, the CD phenotype of infiltrating mononuclear cells, and the number of fibroblasts were analyzed by immunohistochemistry. Compared with 10 non-failing control hearts, significantly higher morphometric area fractions of HLA-ABC and HLA-DR with a concomitant increase of CD3-, CD4- and CD8-positive cells were found to be comparable in 12 patients with idiopathic dilated cardiomyopathy and in 10 patients with secondary heart failure. Furthermore, the similarity of T-cell activation in idiopathic and secondary variants of the disease were substantiated by the following observations: (1) the site-specific distribution of MHC molecules and mononuclear cells in the myocardium was comparable in idiopathic and secondary dilated cardiomyopathy; (2) 6 individuals with lymphocytic aggregates in their myocardium in association with the highest levels of HLA-ABC expression were equally distributed among idiopathic and secondary patient subsets; and (3) expression of HLA-ABC and HLA-DR correlated with that of an endothelial cell marker, von Willebrand factor, in failing myocardia of both study groups. In conclusion, no difference was found in increased MHC molecule expression in failing myocardium of idiopathic and secondary variants of dilated cardiomyopathy, and these entities were not differentially associated with infiltration by increased numbers of T lymphocytes. Hence, we postulate that these immunopathological features are consequences rather than causative factors of myocardial degeneration and dilatation.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum-soluble CD4 as clinical and immunological marker in patients with dilated cardiomyopathy

Serological markers of cell-mediated immunity, i.e., soluble CD4, soluble interleukin-2 (Il-2) receptor and beta 2-microglobulin, were determined in 60 patients with dilated cardiomyopathy. Compared with normal healthy donors (n = 30) and controls who had coronary artery disease with preserved left ventricular function (n = 20), significantly increased levels associated with the New York Heart Association functional classes have been found in the cardiomyopathy patients, irrespectively of the etiology. Out of the immunological variables tested, serum-soluble CD4 most closely reflected the clinical and hemodynamic stage, predicted the presence of lymphocytic aggregates in the myocardium and correlated with the CD4/CD8 ratios of endomyocardial lymphocytes (r = 0.6, P < 0.05). Conversely, focal mononuclear infiltration of the myocardium was associated with significantly elevated CD4/CD8 ratios (2.1 +/- 0.6 vs. 1.3 +/- 0.2, P < 0.05), higher total numbers and percentages of endomyocardial lymphocytes expressing the pan T-markers CD2 and CD3, more CD45RO/UCHL1-positive cells and more CD4-positive T-helper cells, compared with non-reactive cases the lymphocytes of which were scattered throughout the myocardium. In conclusion, in a subset of cardiomyopathy patients lymphocytic clusters in the myocardium indicated an enhanced cellular immune response predominantly mediated by CD4-positive T-helper lymphocytes with active memory function. This immunopathological condition in the heart can be monitored by serum-soluble CD4.