Abstract

To detect serum level of autoantibodies against endothelin-1 receptor type-A (anti-ET1RA) in systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) patients and to evaluate its role as a predictive biomarker in disease-associated pulmonary arterial hypertension (PAH). Methods: 75 patients (25-SLE, 25-SSc, 25-PAH patients due to other entities) and 25 controls were included. Disease activity, functional state of dyspnea, pulmonary function tests, and HRCT chest were performed for SLE and SSc patients—trans-thoracic echocardiography for all patients to detect the signs suggestive of PAH. Serum anti-ET1RA was measured in patients and controls. Results: PAH was detected in 7 SLE patients (28%) and 6 SSc patients (24%). Serum anti-ET1RA antibodies were positive in 4 (57.14 %) SLE patients with PAH, in 5 (83.33%) SSc patients with PAH, and 18 patients (72%) with other entities of PAH. Serum anti-ET1RA was substantially higher in the patients compared to the control group (p=0.001). It was significantly higher in SLE-PAH and SSc-PAH than those without PAH (p=0.001,p<0.0001). Anti-ET1RA positively correlated with the mean pulmonary artery pressure in SLE and SSc patients (p<0.0001). The best-calculated cut-off value of anti-ET1RA to detect PH obtained by ROC analysis was at 10.39U/ml with 73.7% sensitivity and 97.3% specificity. The risk of PAH was assessed using non-adjusted and fully binary logistic regression models. Anti-ET1RA antibodies were the only independent predictor for PAH in patients with SLE and SSc (95%CI;0.34-10.96) (p=0.037). Conclusion: Anti-ET1RA antibodies are detected in SLE and SSc patients with PAH serum. They may serve as a predictive biomarker for PAH in patients with connective tissue diseases

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