The significance of heart-reactive antibodies in heart disease

Presence of circulating anti-myosin antibodies in endomyocardial fibrosis

Background

Endomyocardial Fibrosis (EMF) is a tropical restrictive cardiomyopathy of unknown etiology with high prevalence in Sub-Saharan Africa, for which it is unclear whether the primary target of injury is the endocardial endothelium, the subendocardial fibroblast, the coronary microcirculation or the myocyte. In an attempt to explore the possibility of endocardial lesions being a result of an immune response against the myocyte we assessed the presence and frequency of circulating anti-myocardial antibodies in EMF patients.

Methodology/Principal Findings

EMF classification, assessment of severity and staging was based on echocardiography. We used sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) of myocardial proteins followed by western blotting to screen serum samples for antiheart antibodies G and M classes. The degree of serum reactivity was correlated with the severity and activity of EMF. We studied 56 EMF patients and 10 healthy controls. IgG reactivity against myocardial proteins was stronger and more frequent in patients with EMF when compared to controls (30/56; 53.6% vs. 1/10; 10%, respectively). IgM reactivity was weak in both groups, although higher in EMF patients (11/56; 19.6%) when compared to controls (n = 0). EMF patients showed greater frequency and reactivity of IgG antibodies against myocardial proteins of molecular weights 35 kD, 42 kD and 70 kD (p values <0.01, <0.01 and <0.05 respectively).

Conclusions

The presence of antibodies against myocardial proteins was demonstrated in a subset of EMF patients. These immune markers seem to be related with activity and might provide an adjunct tool for diagnosis and classification of EMF, therefore improving its management by identifying patients who may benefit from immunosuppressive therapy. Further research is needed to clarify the role of autoimmunity in the pathogenesis of EMF.

Endomyocardial Fibrosis is a tropical disease in which the heart cannot open properly to receive blood due to a scar that covers its inner layer. It affects mainly children and adolescents, and has a poor prognosis because the cause and mechanisms of scarring are unknown. The conventional treatment is frustrating and does not alter the natural history of the disease. Despite affecting several million people worldwide there has been little investigation on the mechanisms of the disease or drug development to improve its prognosis. In this study we investigate the presence of antibodies against the myocardial cells of African patients with severe and advanced EMF aiming at uncovering new pathways for the disease. Our results reveal that EMF patients have anti-myocardial antibodies in their blood. The reaction of these antibodies with the heart may be one of the mechanisms involved in the genesis of the fibrotic lesions. This knowledge may help in diagnosing the condition and provide alternatives for its management, using drugs that reduce the impact of the circulating antibodies in the cardiac tissue. The significance of these results needs confirmation on studies involving larger number of subjects due to frequent finding of antiheart antibodies in African populations with heart failure of any cause.

Outcomes for children with acute myocarditis

The optimum treatment for myocarditis in children is unknown. We present outcomes for this disease as seen in a large series of children. Thus, we identified all children seen with myocarditis at Children's Hospital of Pittsburgh since 1985, including only those with biopsy-proven myocarditis, or cardiac dysfunction and proof of concomitant cardiotropic viral infection. Outcomes were defined as complete recovery, incomplete recovery, and death or transplantation. We identified 41 patients, 37 proven by histology, and 4 patients who were too unstable for biopsy but had proof of viral infection. Of the group, 27 (66%) made a complete recovery, 4 (10%) had incomplete recovery, and 10 (24%) either died (5) or underwent transplantation (5). The median time to death or transplantation was 8.4 months, with a range from 1 day to 49 months. Steroids had been administered to 16 patients, of whom 10 made a complete recovery, 2 an incomplete recovery, 2 died, and 2 were transplanted. Intravenous immune globulin was given in isolation to one patient, who made a complete recovery, and to 18 in combination with steroids, of whom 12 made a complete recovery, 2 an incomplete recovery, 2 died, and 2 were transplanted. The remaining 6 patients received neither steroids nor intravenous immune globulin, and of these, 4 made a complete recovery, 1 was transplanted, and 1 died. Freedom from death or transplantation was 81% at 1 year, and 74% at 5 years, with no difference between the modes of treatments. The median time to recovery of function was also comparable between the groups. Thus, in our patients, treatment with intravenous immune globulin appeared to confer no advantage to steroid therapy alone. These data emphasise the need for randomised trials to assess the efficacy of current treatments, as well as that of new therapies.

Post-myocardial infarction pericarditis. Chronic symptoms in a middle-aged man

Post-myocardial infarction pericarditis can be confused with other conditions, including recurrent myocardial ischemia. The decline in the incidence of this type of pericarditis is thought by some to be linked to the decreasing use of anticoagulants in the treatment of myocardial infarction.

Immunity in dilated cardiomyopathy

Although several immunologic parameters have been found to be abnormal, their precise relationship to the cause of the disease remains unclear. It is believed that a virus initiating a bout of myocarditis may play a role in the perpetuation of the chronic phase, probably via immunologic mediation. A selection acquired defect or damage to a subpopulation of suppressor T lymphocytes is possible, providing the basis for the development of an autoimmune disorder. Studies in mice have shown a clear link between active viral myocarditis and the subsequent development of cardiomyopathy. However, the trigger mechanism that initiates the cardiomyopathy is still elusive. Specific antigens, possibly altered virus or damaged cardiac tissue, may be playing the role of the "hidden or cloistered" antigen in eliciting the immunologic reactions through a cytotoxic T-cell mechanism. Identification and isolation of the specific "antigen" in question could resolve the dilemmas about the immunopathogenesis of cardiomyopathy in humans.

Rheumatic heart disease and thyroid status

A retrospective analysis of 76 patients with rheumatic heart disease revealed nine with thyrotoxicosis, three with hypothyroidism and seven with normal thyroid function and circulating thyroid antibodies. This suggests that there may be an association between rheumatic heart disease and thyroid dysfunction. The findings emphasize the need to formally exclude hyperthyroidism in patients with atrial fibrillation whatever the apparent cause. They also imply a possible autoimmune factor in the pathogenesis of rheumatic heart disease and suggest that patients with rheumatic heart disease may develop clinical or sub-clinical thyroid disease.

Leucocyte migration inhibition test in cases of ischaemic heart disease

Cases of ischaemic heart disease have been studied for the cell-mediated immune response against human heart antigen by using the leucocyte migration inhibition test. In 30 cases of acute myocardial infarction, the leucocyte migration inhibition values started increasing from the first week reaching a peak in 3 to 4 weeks and then declining but still above control values 12 months after infarction. The leucocyte migration inhibition values were significantly higher than control values in another 10 patients with late complications of previous infarction and in those patients with acute myocardial infarction who were less than 40 years of age, who had extensive anterior infarction, or who had a past history of angina pectoris. The leucocyte migration inhibition values were negligible in all the 12 patients with stable angina pectoris, but were high in 2 of the 8 with unstable angina and in 3 of the 4 with the intermediate coronary syndrome. The leucocyte migration inhibition values were much higher in patients with complications, which may be the result of cardiac damage by a cell-mediated immune response.

Cardiac tamponade with nonhemorrhagic pericardial fluid complicating Dressler's syndrome

A 39-year-old man developed cardiac tamponade with Dressler's syndrome four weeks after an inferior myocardial infarction. Treatment of the tamponade by pericardiocentesis on two occasions produced serous fluid. The pericardial effusion cleared with short-term therapy with corticosteroids and the prolonged use of indomethacin.