Idiopathic dilated cardiomyopathy: lack of association between circulating organ-specific cardiac antibodies and HLA-DR antigens

Cardiac Autoimmunity: Myocarditis

Myocarditis is the inflammation of the muscle tissues of the heart (myocardium). After a pathologic cardiac-specific inflammatory process, it may progress to chronic damage and dilated cardiomyopathy. The latter is characterized by systolic dysfunction, whose clinical correlate is heart failure. Nevertheless, other acute complications may arise as consequence of tissue damage and electrophysiologic disturbances. Different etiologies are involved in triggering myocarditis. In some cases, such as giant cell myocarditis or eosinophilic necrotizing myocarditis, it is an autoimmune process. Several factors predispose the development of autoimmune myocarditis such as systemic/local primary autoimmunity, viral infection, HLA and gender bias, exposure of cryptic antigens, mimicry, and deficient thymic training/Treg induction. Once the anti-myocardium autoimmune process is triggered, several components of the immune response orchestrate a sustained attack toward myocardial tissues with particular timing and immunopathogenic features. Innate response mediated by monocytes/macrophages, neutrophils, and eosinophils parallels the adaptive response, playing a final effector role and not only a priming function. Stromal cells like fibroblast are also involved in the process through specific cytokines. Furthermore, adaptive T cell responses have anti-paradigmatic features, as Th17 response is dispensable for acute myocarditis but is the main driver of the process leading to dilated cardiomyopathy. Humoral response, thought to be a bystander, is important in the appearance of late-stage hemodynamic complications. The complexity of that process, as well as the unspecific and variable clinical presentation, had generated difficulties for diagnosis and treatment, which remain suboptimal. In this chapter, we will discuss the most relevant immunopathogenic findings from a basic science and clinical perspective.

HLA-DR3 antigen in the resistance to idiopathic dilated cardiomyopathy

Idiopathic dilated cardiomyopathy (IDC) has been hypothesized as a multifactorial disorder initiated by an environment trigger in individuals with predisposing human leukocyte antigen (HLA) alleles. Published data on the association between HLA-DR3 antigen and IDC risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. Studies were identified by searching the PUBMED and Embase database (starting from June 2015). A total of 19 case-control studies including 1378 cases and 10383 controls provided data on the association between HLA-DR3 antigen and genetic susceptibility to IDC. Overall, significantly decreased frequency of HLA-DR3 allele (OR=0.72; 95%CI=0.58-0.90; P=0.004) was found in patients with IDC compared with controls. When stratified by myocardial biopsy or non-biopsy cases, statistically decreased risk was found for IDC in myocardial biopsy cases (OR=0.69; 95%CI=0.57-0.84; P=0.0003). In the subgroup analysis by ethnicity, borderline statistically significantly decreased risk was found among Europeans from 12 case-control studies (OR=0.76; 95%CI=0.58-1.00; P=0.05). In conclusion, our results suggest that individuals with HLA-DR3 antigen may have a protective effect against IDC.

Human leukocyte antigen-DQ beta 1 chain (DQB1) gene polymorphisms are associated with dilated cardiomyopathy: a systematic review and meta-analysis

BACKGROUND

Previous studies reported an association between the human leukocyte antigen (HLA)-DQ antigen beta 1 chain (DQB1) alleles and dilated cardiomyopathy (DCM). However, the results of those studies have been inconsistent. To clarify the association between HLA-DQB1 and DCM, we performed a systematic review and meta-analysis of case-control studies.

METHODS

Searches were performed using the PubMed database, the Excerpta Medica Database (EMBASE), the Cochrane Central Register of Controlled Trials database, the Science Citation Index database, the China Biology Medicine disc, the China National Knowledge Information database, the Wanfang database, and the Chinese Scientific and Technological Journal Database (VIP database). The search terms included "dilated cardiomyopathy" and "DQB1." Ten case-controlled studies were included in the systematic review to assess the association between DCM and the HLA-DQB1*0201, *0302, *0504, *0301, and *0602 alleles.

RESULTS

In total, 8 studies were included in the meta-analysis of the HLA-DQB1 *0201 allele. The pooled odds risk (OR) for this allele was .47, with a 95% confidence interval (CI) of .28 to .77 (P < .01). With respect to the HLA-DQB1 *0504 allele, only 3 studies were included in our meta-analysis. The pooled OR was .36 (95% CI, .15 to .84; P < .05). Nine, 8, and 7 studies of the HLA-DQB1 *0301, *0302, and *0602 alleles, respectively, were included in our meta-analysis. No statistically significant difference was evident in the frequency of these 3 alleles between the DCM and normal control groups.

CONCLUSION

The HLA-DQB1 *0201 and *0504 alleles may be protective against DCM.

HLA-DRB1 gene polymorphism is associated with idiopathic dilated cardiomyopathy: a meta-analysis

OBJECTIVE

Some studies have reported that the HLA-DRB1 allele was associated with idiopathic dilated cardiomyopathy. However, there have been inconsistent results among different studies. To clarify the association of HLA-DRB1 and idiopathic dilated cardiomyopathy, a meta-analysis of case-control studies was performed.

METHODS

PubMed database, Science Citation Index database, The Cochrane Central Register of Controlled Trials database, China National Knowledge Information database, Chinese Biomedical Literature database, Wanfang database, and VIP database in China were searched. Search terms included dilated cardiomyopathy and DRB1. Five case-control studies were included in the present meta-analysis to assess the association between HLA-DRB1*1401, HLA-DRB1*0901, HLA-DRB1*0301, and idiopathic dilated cardiomyopathy.

RESULTS

A total of four studies were included in our meta-analysis for HLA-DRB1*1401 and HLA-DRB1*0901. The pooled odds ratio (OR) was 2.6 [95% confidence interval (CI) 1.11-6.11, P<0.05] and 0.70 (95% CI 0.48-1.00, P=0.05), respectively. For the HLA-DRB1*0301 allele, just three studies were included in our meta-analysis. The pooled OR was 0.49 (95% CI 0.27-0.91, P<0.05). The present meta-analysis indicated that the frequency of HLA-DRB1*1401 was higher in idiopathic dilated cardiomyopathy patients than in healthy people, whereas HLA-DRB1*0901 and HLA-DRB1*0301 were higher in healthy people than in idiopathic dilated cardiomyopathy patients.

CONCLUSION

The HLA-DRB1*1401 allele might be a risk factor for idiopathic dilated cardiomyopathy and HLA-DRB1*0901 and HLA-DRB1*0301 might protect humans from idiopathic dilated cardiomyopathy.

A meta-analysis of HLA-DR polymorphism and genetic susceptibility to idiopathic dilated cardiomyopathy

Idiopathic dilated cardiomyopathy (IDC) has been hypothesized as a multifactorial disorder initiated by an environment trigger in individuals with predisposing human leukocyte antigen (HLA) alleles. Published data on the association between HLA-DR polymorphism and IDC risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. A total of 19 case-control studies including 1,378 cases and 10,383 controls provided data on the association between HLA-DR polymorphism and genetic susceptibility to IDC. Overall, statistically elevated frequencies of HLA-DR4 (OR 1.58; 95% CI 1.21-2.07; P=0.0009) and HLA-DR5 (OR 1.35; 95% CI 1.05-1.73; P=0.02) alleles were found in patients with IDC compared with controls. Individuals with HLA-DR3 antigen have a protective effect against IDC (OR 0.72; 95% CI 0.58-0.90; P=0.004). In summary, this meta-analysis indicated that certain HLA-DR alleles may be genetic markers for susceptibility and resistance to IDC.

Association of HLA class II DRB1, DPA1 and DPB1 polymorphism with genetic susceptibility to idiopathic dilated cardiomyopathy in Chinese Han nationality

Although the aetiology of idiopathic dilated cardiomyopathy (IDC) remains unclear, many immunological abnormalities involving changes in cell-mediated and humoral immunity may be associated with cardiac impairment in IDC. Autoimmune mechanisms are likely to participate in the pathogenesis of at least a subgroup of IDC and components of the major histocompatibility complex may serve as markers for the propensity to develop immune-mediated myocardial damage. Human leukocyte antigen (HLA) class II genes, which are highly polymorphic, play an important role in the activating of immune responses and thus control the predisposition for or protection from IDC. This study explores the possible contribution of HLA-DRB and DP polymorphisms to IDC susceptibility. DNA genotyping for HLA-DRB1, DPA1 and DPB1 was performed using polymerase chain reaction-sequencing based typing (PCR-SBT) method in 198 IDC patients and 136 random selected healthy Han ethnic individuals living in Northern China. IDC patients were, sub-grouped into asymptomatics (subgroup A), with arrhythmia (subgroup B) and with overt congestive heart failure (subgroup C) according to the clinical manifestations and electrocardiogram or echocardiographic characteristics. ADP/ATP autoantibody was detected in IDC group by immunoblot analysis. The results revealed that HLA-DR15, -DPB*0601 frequencies were significantly elevated in IDC group compared with normal control. The DPB1*0601 allele in homozygous form or in combination with allele DPB1*2301 or *3901, was found present more often in IDC patients. The predominance of HLA-DR4 allele was observed in subgroup B after stratification. However, the frequency of DPB1*0101 allele increased in the control than in the IDC group. The frequency of HLA-DPB1*0601 allele was significantly higher in IDC patients with positive autoantibody against ADP/ATP carrier of myocardial mitochondria in contrast to those with negative autoantibody. We conclude that HLA-DR4, -DR15, -DPB1*0601 alleles confers susceptibility to, while DPB1*0101 allele confers protection from IDC among individuals of northern Chinese Han nationality. The glutamate at position 69 in the second exon of DPB1*0601, as a key residue for special conformation of HLA-DP, may confer predisposition to IDC. HLA-DR and -DP alleles polymorphisms may serve as genetic markers for IDC and be involved in the regulation of the immune specific response to auto or exterior anti-myocardium antibodies.

Autoimmune markers are undetectable in end stage idiopathic dilated cardiomyopathy

BACKGROUND

Autoreactive humoral and cellular immune responses may be involved in the pathogenesis of idiopathic dilated cardiomyopathy (IDC). Certain human leucocyte antigens (HLA) could also be linked to the development of IDC.

AIM

To determine whether various markers of autoimmunity are present in the final phase of the disease, to substantiate the role of an autoimmune process in IDC.

METHODS

37 patients with end stage IDC were studied, together with 39 patients with end stage heart disease of known aetiology who were included for comparison. Multiple myocardial tissue samples from the explanted heart of each patient were evaluated (immuno)histologically. An indirect immunofluorescence assay was used to screen patient serum samples for the presence of heart specific autoantibodies. HLA class I and II frequencies were determined in each group and compared with HLA frequencies from healthy blood donors.

RESULTS

Only scanty small mononuclear cell infiltrates were present in myocardial tissue of seven patients with IDC and of 11 patients with heart disease of known cause. The majority of these inflammatory cells were negative for T cell markers. All blood specimens were negative for heart specific autoantibodies and there was no apparent association of IDC with particular HLA phenotypes.

CONCLUSIONS

These findings suggest that an active autoimmune process is not involved in the end stage of IDC.

Familial dilated cardiomyopathy: evidence for genetic and phenotypic heterogeneity. Heart Muscle Disease Study Group

OBJECTIVES

This study was performed to evaluate the characteristics, mode of inheritance and etiology of familial dilated cardiomyopathy (FDC).

BACKGROUND

A genetic form of disease transmission has been identified in a relevant proportion of patients with dilated cardiomyopathy (DCM). Variable clinical characteristics and patterns of inheritance, and an increased frequency of cardiac antibodies have been reported. An analysis of FDC may improve the understanding of the disease and the management of patients.

METHODS

Of 350 consecutive patients with idiopathic DCM, 281 relatives from 60 families were examined. Family studies included clinical examination, electrocardiography, echocardiography and blood sampling. Of the 60 DCM index patients examined, 39 were attributable to FDC and 21 were due to sporadic DCM. Clinical features, histology, mode of inheritance and autoimmune serology were examined, molecular genetic studies were undertaken and the difference between familial and sporadic forms was analyzed.

RESULTS

Only a younger age (p = 0.0005) and a higher ejection fraction (p = 0.03) could clinically distinguish FDC patients from those with sporadic DCM. However, a number of distinct subtypes of FDC were identified: 1) autosomal dominant, the most frequent form (56%); 2) autosomal recessive (16%), characterized by worse prognosis; 3) X-linked FDC (10%), with different mutations of the dystrophin gene; 4) a novel form of autosomal dominant DCM with subclinical skeletal muscle disease (7.7%); 5) FDC with conduction defects (2.6%), and 6) rare unclassifiable forms (7.7%). The forms with skeletal muscle involvement were characterized by a restrictive filling pattern; the forms with isolated cardiomyopathy had an increased frequency of organ-specific cardiac autoantibodies. Histologic signs of myocarditis were frequent and nonspecific.

CONCLUSIONS

Familial dilated cardiomyopathy is frequent, cannot be predicted on a clinical or morphologic basis and requires family screening for identification. The phenotypic heterogeneity, different patterns of transmission, different frequencies of cardiac autoantibodies and the initial molecular genetic data indicate that multiple genes and pathogenetic mechanisms can lead to FDC.

Autoimmunity in myocarditis: relevance of animal models

Infections (viruses, bacteria, protozoa, fungi) are major etiological factors causing clinical myocarditis and dilated cardiomyopathy. In many patients and symptom-free relatives antibodies and T cells reactive to heart antigens are detected, which implies that autoimmunity is probably a major pathogenic mechanism of cardiac injury. Animal models have been established to elucidate how infections initiate autoimmunity and how autoimmune mediators cause death or transient dysfunction of myocytes. Two major types of experimental models are discussed: adjuvant-induced myocarditis, in which animals are given multiple immunizations of heart proteins (myosin, adenine nucleotide translocator); and virus-induced myocarditis, in which animals are infected with the viruses predominantly associated with the human disease.

Cardiac autoantibodies in dilated cardiomyopathy become undetectable with disease progression

OBJECTIVE

To determine the relation of cardiac autoantibody and disease status in a consecutive series of patients with dilated cardiomyopathy by prospective antibody testing at diagnosis and at follow up.

METHODS

Antibody status was assessed by indirect immunofluorescence in 110 patients with dilated cardiomyopathy (85 male, mean (SD) age 44 (13) years) at diagnosis and at follow up (mean (SD) 14 (12) months); in 57 of them cardiac specific anti-alpha myosin antibody titres were also measured by an enzyme-linked immunosorbent assay (ELISA). Patients underwent complete evaluation at diagnosis and clinical and non-invasive assessment at follow up, including exercise testing with maximal oxygen consumption measurements.

RESULTS

The frequency of cardiac specific antibodies by immunofluorescence was lower at follow up than at diagnosis (28 (25%) v 11 (10%), P = 0.002). Mean (SEM) anti-alpha myosin antibody titres at follow up were also lower than at diagnosis (0.24 (0.02) v 0.30 (0.02), P = 0.038); 24% of patients at diagnosis and 14% at follow up had an abnormal ELISA result. None of the patients who were negative by immunofluorescence or ELISA at diagnosis became positive at follow up. Presence of antibody at diagnosis was associated with milder symptoms and greater exercise capacity at follow up and persistence of antibody at follow up was associated with stable disease and milder symptoms at diagnosis.

CONCLUSIONS

Cardiac specific autoantibodies in dilated cardiomyopathy become undetectable with disease progression; this is a recognised feature of other autoimmune conditions, such as type 1 diabetes. Detection of these antibodies at diagnosis and at follow up may provide a non-invasive marker of early dilated cardiomyopathy.

Increased frequency of organ-specific cardiac antibodies in healthy relatives of patients with dilated cardiomyopathy: evidence for autoimmunity in Polish families

BACKGROUND AND HYPOTHESIS

Autoantibodies represent markers of autoimmune involvement and are found with increased frequency in patients and their symptom-free relatives at risk compared with normal controls. Cardiac-specific autoantibodies, detected by immunofluorescence, were found in 20% of symptom-free relative of patients with dilated cardiomyopathy (DCM) from England and Italy. The role of autoimmunity may vary in DCM patients from Poland due to ethnic differences in genetic susceptibility to autoimmune disease.

METHODS

We assessed the frequency of the organ-specific cardiac autoantibodies in 162 symptom-free relatives of DCM patients [85 male, mean (SD) age 27 (18) years] and 80 control subjects from Poland. Familial DCM (> 1 affected member) was present in 4 families, nonfamilial DCM in the remaining 24 pedigrees. We performed antibody screening and noninvasive cardiological assessment in the whole group.

RESULTS

The frequency of cardiac-specific autoantibodies was higher among patients with documented DCM (probands and relatives) (50%) and their symptom-free relatives (38%) than in unrelated normal subjects (10%; p = 0.0001). In 24 (86%) of the pedigrees studied, autoantibodies were found in the proband and/or in at least one family member and tended to be more common in familial than in nonfamilial DCM (50 vs. 35%, p = NS). Echocardiographic indices of left ventricular size and function were similar in relatives with and without detectable antibodies.

CONCLUSIONS

The presence of cardiac-specific autoantibodies in symptom-free relatives of DCM patients provides evidence for autoimmunity in the majority (86%) of our pedigrees, including both familial and nonfamilial forms of DCM.

HLA antigens in an Omani population with dilated cardiomyopathy

We have investigated the frequency of HLA antigens in 50 Omanis with idiopathic dilated cardiomyopathy to establish whether there are ethnic/racial differences in the reported HLA associations with this disease. There were no statistically significant HLA-A, B, C, DR or DQ antigen frequency differences between the patients and 247 healthy Omanis. THe reported association of HLA-DR4 with idiopathic dilated cardiomyopathy in the Caucasian population does not apply to the Omanis. This confirms the heterogeneity of this disease and points to ethnic/racial origins as important factors when examining the HLA association. This is particularly pertinent as HLD-DR4 has been strongly linked to autoantibody formation in idiopathic dilated cardiomyopathy in Caucasians. The lack of any HLA antigen association in Omanis would argue against the proposed HLA-linked autoimmune pathology of idiopathic dilated cardiomyopathy.

Evidence for autoimmunity to myosin and other heart-specific autoantigens in patients with dilated cardiomyopathy and their relatives

Autoimmune disease is characterised by the presence of circulating autoantibodies in the affected patients and in a proportion of their relatives. These antibodies are generally not pathogenic but are reliable markers of immune-mediated tissue damage. In organ-specific autoimmune disease, the destruction process is largely restricted to one organ within the body and the autoantibodies react with autoantigens which are unique to the diseased target organ. At least in a patient subset, myocarditis and dilated cardiomyopathy (DCM) may represent the acute and chronic stages of a progressive organ-specific autoimmune disease of the myocardium. Autoimmune features in patients with myocarditis/DCM include: familial aggregation, a weak association with HLA-DR4, abnormal expression of HLA class II on cardiac endothelium on endomyocardial biopsy, and detection of organ- and disease-specific cardiac autoantibodies, by immunofluorescence and absorption techniques, in the affected patients and in a proportion of their symptom-free relatives from both familial and non-familial DCM pedigrees. The organ-specific cardiac autoantibodies detected by immunofluorescence are directed against multiple antigens. One of these, first identified using immunoblotting and confirmed by ELISA, is the cardiac-specific alpha-myosin isoform. Myosin fulfils the expected criteria for organ-specific autoimmunity, in that immunisation with cardiac but not skeletal myosin reproduces, in susceptible mouse strains, the human disease phenotype of DCM; in addition, alpha-myosin is entirely cardiac-specific and is only expressed in the myocardium. Using ELISA, high titer organ- and disease-specific anti alpha-myosin antibodies have been found in 16% of the symptom-free relatives of DCM patients and in 38% of the pedigrees of the same cohort of relatives studied by immunofluorescence. The ELISA results provide additional evidence for autoimmunity in a subset of DCM families, and emphasise the importance of alpha-myosin as a target antigen.

Autoimmunity in dilated cardiomyopathy and the major histocompatibility complex

Autoimmune mechanisms are likely to participate in the pathogenesis of a subgroup of dilated cardiomyopathy. These mechanisms involve the elaboration of autoantibodies against cardiac proteins as well as abnormal lymphocyte regulation. The presence of autoantibodies against beta-adrenoceptors correlates with the human leukocyte antigen (HLA)-DR4/1 phenotypes and specific T-cell receptor haplotypes. In addition, histidine at position 36 of the HLA-DQ beta 1 gene is associated with the presence of clinically manifest dilated cardiomyopathy. Components of the major histocompatibility complex (MHC) may thus serve as markers for the propensity to develop immune-mediated myocardial damage.

DNA typing of HLA class II genes in Japanese patients with dilated cardiomyopathy

HLA class II genes (DRB, DQA, DQB, DPA, and DPB) were typed at the DNA level using polymerase chain reaction/sequence-specific oligonucleotide probe analysis in 78 unrelated patients with DCM and 336 unrelated healthy controls to elucidate the HLA alleles or HLA haplotypes associated with DCM. The frequencies of DRB1*1401 (15.4% v 4.5%, RR = 3.90, P < 0.0005, Pc < 0.03), DQB1*0503 (14.1% v 5.4%, RR = 2.93, P < 0.007) and DRB1*1401-DQB1*0503 haplotype (11.5% v 1.5%, RR = 8.24, P < 0.00001, Pc < 0.01) were increased in the DCM patients. The frequency of HLA-DRB1*1101 (9.0% v 3.0%, RR = 3.26, P < 0.02) also was increased in the patients. In addition, the frequencies of DQB1*0604 and DPB1*0401 were increased in the DRB1*1401 and DRB1*1101 negative patients. In contrast, the frequencies of DQB1*0303 (19.2% v 30.7%, RR = 0.55, P < 0.05) and DRB1*0901-DQB1*0303 haplotype (16.7% v 29.8%, RR = 0.49, P < 0.02) were decreased in the DCM group. Disease susceptibility to DCM in the Japanese population, thus, may be controlled in part by a gene (or genes) in close linkage disequilibrium with DRB1*1401-DQB1*0503, DRB1*1101-DQB1*0301, and DQB1*0604-DPB1*0401 haplotypes, while the resistance to DCM may be associated with the DRB1*0901-DQB1*0303 haplotype.

The autoimmune basis of dilated cardiomyopathy

Dilated cardiomyopathy is a form of heart disease characterized by ventricular dilatation and reduced systolic function. In most patients, dilated cardiomyopathy is a sporadic disease. However, 20% of dilated cardiomyopathy patients may have a familial form of the disease. The aetiologies of both the sporadic and familial forms of dilated cardiomyopathy are unknown in most cases. Dilated cardiomyopathy has a spectrum of clinical and subclinical presentations. During the last 10 years, there have been many investigations concerning the possible aetiologic role of immune factors in dilated cardiomyopathy. It is plausible that an antecedent viral infection initiates an immunological cascade which in turn leads to production of autoimmune antibodies resulting in dilated cardiomyopathy. However, in most dilated cardiomyopathy patients, an antecedent viral infection cannot be identified. Similarly, the trail of immunological research has diverged as different groups have identified distinct autoantibodies or other immune factors in heterogeneous subsets of dilated cardiomyopathy and control patients. In this manuscript, we review the studies which have contributed supportive and confounding evidence to the theoretical autoimmune basis of dilated cardiomyopathy.

Evidence from family studies for autoimmunity in dilated cardiomyopathy

Organ-specific antibodies are found in patients with autoimmune disease and their symptom-free relatives many years before clinical onset. Organ-specific cardiac antibodies can be found in patients with dilated cardiomyopathy (DCM) and their relatives, which supports the idea that DCM is an autoimmune disease. We did non-invasive cardiological assessment and antibody screening in 342 symptom-free relatives (170 male, 172 female, mean [SD] age 31 [16] years). 177 relatives were from 33 families with more than 1 affected individual (familial DCM) and 165 relatives from 31 families with only 1 affected member (non-familial DCM). The frequency of cardiac antibodies was higher among relatives of DCM patients than in controls (20% vs 3.5%, p = 0.0001). In 37 (58%) of the families studied, cardiac antibodies were found in the proband and/or in at least 1 family member and were more common in familial than in non-familial DCM (24% vs 15%, p = 0.036). Antibody-positive relatives were younger (26 [15] vs 33 [17] years, p = 0.01) and had a larger mean echocardiographic left ventricular end-systolic dimension (35 [6] vs 32 [6], p = 0.01 mm) and reduced percentage fractional shortening compared with antibody-negative relatives (31 [6] vs 34 [6], p = 0.008). Presence of cardiac-specific autoantibodies in symptom-free DCM relatives provides evidence of autoimmunity in a subset of our patients (58%), including familial and non-familial forms of DCM. These antibodies are associated with mild left ventricular systolic dysfunction on echocardiography and may be early markers for relatives at risk of DCM.

Anti-beta-receptor antibodies in familial cardiomyopathy: correlation with HLA-DR and HLA-DQ gene polymorphisms

The presence of beta-receptor autoantibodies and their relationship to restriction fragment length polymorphisms of the human leukocyte antigen (HLA) class II genes were studied in 42 affected and unaffected members of a family with a heritable disorder of the conduction system and cardiac muscle. Antibodies were detected in 34% of all members (59% of affected and 22% of unaffected; p < 0.01). Significant differences between affected and unaffected individuals and between anti-beta-receptor antibody positive and negative individuals were noted in the prevalence of polymorphisms obtained with Taq I for the HLA-DR beta and HLA-DQ alpha genes. In affected individuals, there was a strong positive correlation between these polymorphisms and the presence of anti-beta-receptor antibodies. These results suggest that autoimmune mechanisms under the control of the class II genes play an important role in the pathogenesis of familial cardiomyopathy.

Do specific HLA antigens predispose to ischaemic heart disease or idiopathic dilated cardiomyopathy?

BACKGROUND

The aetiology of idiopathic dilated cardiomyopathy is believed to have an immunological component. Association with human leucocyte antigens (HLAs) has been previously reported, particularly with HLA-DR4.

AIM

To determine the association of HLA type with diagnosis in a group of patients assessed for heart transplantation.

METHODS

A comparison was made of frequencies of HLA types in patients with a diagnosis of idiopathic dilated cardiomyopathy or (n = 98) ischaemic heart disease (n = 170) and in controls from the North Western region (n = 857).

RESULTS

Neither the patients with idiopathic dilated cardiomyopathy nor those with ischaemic heart disease showed a significant increase or decrease in any HLA frequency compared with the controls.

CONCLUSION

These results suggest that there is no HLA association with idiopathic dilated cardiomyopathy or ischaemic heart disease. This conflicts with the results of some previous studies.

Comparison of clinical findings in idiopathic dilated cardiomyopathy in women versus men. The Italian Multicenter Cardiomyopathy Study Group (SPIC)

Clinical and laboratory findings were compared in 65 women and 238 men with invasively documented idiopathic dilated cardiomyopathy. Women had more severe symptoms (New York Heart Association class > or = III in 48 vs 39%; p < 0.05), presented more frequently with heart failure signs (63 vs 41%; p < 0.01), and had a higher cardiothoracic ratio (0.56 +/- 0.06 vs 0.53 +/- 0.06; p < 0.05) and higher frequency of left bundle branch block (41 vs 29%; p < 0.05). Echocardiographic measurements in women showed significantly greater left ventricular (LV) end-diastolic (42 +/- 7 vs 39 +/- 6 mm/m2; p < 0.0001) and end-systolic (36 +/- 7 vs 33 +/- 6 mm/m2; p < 0.001) diameters, and mean myocardial thickness (11 +/- 2 vs 10 +/- 2 mm; p < 0.05). Exercise duration was shorter in women than in men (7 +/- 3 vs 10 +/- 4 minutes; p < 0.001). After 18 +/- 16 months, 9 women and 27 men died, and 7 and 17, respectively, received transplants. Transplant-free survival was not significantly different according to gender. By Cox multivariate analysis, LV ejection fraction was a significant independent predictor of cardiac death or heart transplantation in both sexes (p < 0.05 in men, and p < 0.005 in women), together with left atrial diameter index (p < 0.01) in women, and mean pulmonary artery pressure (p < 0.001) in men. In conclusion, women with idiopathic dilated cardiomyopathy present a more advanced phase of the disease with greater LV dilation, but do not have a different prognosis.