Abstract
Background: Sarcoidosis is an immune-mediated disease. Cardiac involvement, a granulomatous form of myocarditis, is under-recognized and prognostically relevant. Anti-heart autoantibodies (AHAs) and anti-intercalated disk autoantibodies (AIDAs) are autoimmune markers in nonsarcoidosis myocarditis forms. Objective: The aim was to assess serum AHAs and AIDAs as autoimmune markers in cardiac sarcoidosis. Methods: This is a cross-sectional study on AHA and AIDA frequency in: 29 patients (aged 46 ± 12, 20 male) with biopsy-proven extracardiac sarcoidosis and biopsy-proven or clinically suspected and confirmed by 18-fluorodeoxyglucose positron emission tomography and/or cardiovascular magnetic resonance (CMR) cardiac involvement; 30 patients (aged 44 ± 11, 12 male) with biopsy-proven extracardiac sarcoidosis without cardiac involvement (no cardiac symptoms, normal 12-lead electrocardiogram, echocardiography and CMR), and control patients with noninflammatory cardiac disease (NICD) (n = 160), ischemic heart failure (IHF) (n = 141) and normal blood donors (NBDs) (n = 270). Sarcoidosis patients were recruited in two recruiting tertiary centers in the USA and Italy. AHAs and AIDAs were detected by indirect immunofluorescence on the human myocardium and skeletal muscle. Results: AHA and AIDA frequencies were higher in sarcoidosis with cardiac involvement (86%; 62%) than in sarcoidosis without cardiac involvement (0%; 0%), NICD (8%; 4%), IHF (7%; 2%) and NBD (9%; 0%) (p = 0.0001; p = 0.0001, respectively). Sensitivity and specificity for cardiac sarcoidosis were 86% and 92% for positive AHAs and 62% and 98% for positive AIDAs, respectively. AIDAs in cardiac sarcoidosis were associated with a higher number of involved organs (p = 0.04). Conclusions: Serum AHAs and AIDAs provide novel noninvasive diagnostic autoimmune markers for cardiac sarcoidosis.
Highlights
Sarcoidosis is a systemic granulomatous disease of still unknown etiology that can involve any organ or system, including the heart [1,2,3,4,5,6,7,8,9,10,11]
anti-intercalated disk autoantibodies (AIDAs) were higher in cardiac sarcoidosis (86%; 62%) than sarcoidosis without cardiac involvement (0, 0%; 0, 0%), in noninflammatory cardiac disease (NICD) (8%; 4%), ischemic heart failure (IHF) (7%; 2%) and normal blood donors (NBDs) (9%; 0%) (p = 0.0001; p = 0.0001, respectively)
The frequency of Anti-heart autoantibodies (AHAs) and AIDAs in cardiac sarcoidosis was similar to that found in classical organ-specific nonsarcoidotic autoimmune myocarditis [20,23], supporting the involvement of autoimmunity in cardiac sarcoidosis and in keeping with the growing evidence that B-cells and autoimmunity may play a role in sarcoidosis pathogenesis [24,25]
Summary
Sarcoidosis is a systemic granulomatous disease of still unknown etiology that can involve any organ or system, including the heart [1,2,3,4,5,6,7,8,9,10,11]. Cardiac involvement is considered a major clinical presentation, as it involves a sizable proportion of patients [1,4,9]; if not promptly recognized and treated, it is associated with poor prognosis [8]. The identification of reliable biomarkers of early and/or subclinical cardiac involvement, including serum autoantibodies [14,15], would be essential for both early diagnosis and therapeutic intervention, which can reduce morbidity and mortality. To assess the potential role of AHAs and AIDAs as noninvasive biomarkers of cardiac sarcoidosis, we evaluated the frequency of AHAs and AIDAs in sera from a cohort of patients with a biopsy-confirmed diagnosis of extracardiac sarcoidosis and biopsy-proven or clinically suspected cardiac involvement [3,23], as well as in an age-matched group of patients with a biopsy-confirmed diagnosis of extracardiac sarcoidosis without cardiac involvement
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