Autoantibodies to types I and IV collagen and heart valve disease in systemic lupus erythematosus/antiphospholipid syndrome

Introduction/objectives autoantibodies to types I and IV collagen have been described in rheumatic fever and infective endocarditis. We tried to elucidate if an autoimmune response against collagens I and IV exists, associated with heart valve disease in systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS). A cohort of 172 patients with SLE (n = 79), primary APS (PAPS, n = 83), and secondary APS (n = 10) were assessed for valvulopathy by transthoracic echocardiograms. Autoantibodies to types I and IV collagen were assessed in patients and 50 controls, setting autoantibody positivity at two standard deviations above the mean antibody level of controls. Positive anticollagen IV antibody rate was significantly higher in SLE patients (17.7%) in respect to the rest of groups (PAPS 2.4%, controls 2%; P = 0.001). Percentage of positive autoantibodies to collagen I was similar in SLE and APS cohort of patients with and without valvular disease (48.4 vs 51.6%, respectively; P = 0.45). Percentage of positive autoantibodies to collagen IV was increased but not significantly in SLE and APS cohort of patients with respect to those without valvular disease (62.5 vs 37.5%, respectively; P = 0.08). Mean (standard deviation) levels of positive anticollagen I and IV antibodies did not differ between patients with and without valvular disease (85.6 ± 55 vs 81 ± 85 U/ml, respectively; P = 0.86 for anticollagen I) (0.05 ± 0.02 vs 0.12 ± 0.16 U/ml, respectively; P = 0.34 for anticollagen IV). Our data indicate a lack of association of autoantibodies to types I and IV collagen with heart valve disease in SLE and APS.