Streptococcal-vimentin cross-reactive antibodies induce microvascular cardiac endothelial proinflammatory phenotype in rheumatic heart disease.

Rheumatic heart disease (RHD) is characterized by the presence of anti-streptococcal group A antibodies and anti-endothelial cell antibodies (AECA). Molecular mimicry between streptococcal antigens and self proteins is a hallmark of the pathogenesis of rheumatic fever. We aimed to identify, in RHD patients, autoantibodies specific to endothelial autoantigens cross-reactive with streptococcal proteins and to evaluate their role in inducing endothelial damage. We used an immunoproteomic approach with endothelial cell-surface membrane proteins in order to identify autoantigens recognized by AECA of 140 RHD patients. Cross-reactivity of purified antibodies with streptococcal proteins was analysed. Homologous peptides recognized by serum cross-reactive antibodies were found through comparing the amino acid sequence of streptococcal antigens with human antigens. To investigate interleukin (IL)-1R-associated kinase (IRAK1) and nuclear factor-κB (NF-κB) activation, we performed a Western blot analysis of whole extracts proteins from unstimulated or stimulated human microvascular cardiac endothelial cells (HMVEC-C). Adhesion molecule expression and release of proinflammatory cytokines and growth factors were studied by multiplex bead based immunoassay kits. We observed anti-vimentin antibodies in sera from 49% RHD AECA-positive patients. Cross-reactivity of purified anti-vimentin antibodies with heat shock protein (HSP)70 and streptopain streptococcal proteins was shown. Comparing the amino acid sequence of streptococcal HSP70 and streptopain with human vimentin, we found two homologous peptides recognized by serum cross-reactive antibodies. These antibodies were able to stimulate HMVEC-C inducing IRAK and NF-κB activation, adhesion molecule expression and release of proinflammatory cytokines and growth factors. In conclusion, streptococcal-vimentin cross-reactive antibodies were able to activate microvascular cardiac endothelium by amplifying the inflammatory response in RHD.

Anti-endothelial cell antibodies in rheumatic heart disease.

To evaluate the anti-endothelial cell antibodies (AECA), anti-cardiolipin antibodies (aCL) and serum mannose-binding lectin (MBL) profiles of a large cohort of Yemeni patients with rheumatic heart disease (RHD) and to correlate these findings with clinical features of the disease. Patients (n = 140) were recruited from Al-Thawra Hospital in Sana'a, Yemen. All had RHD diagnosed according to modified Jones' criteria. We also studied 140 sex- and age-matched healthy blood donors from the same area. Echocardiography was performed according to the recommendations of the American Society of Echocardiography. Solid phase enzyme-linked immunosorbent assays (ELISAs) were used to measure AECA and aCL titres and serum MBL levels. Forty per cent of the patients were AECA-positive, but only 7·8% were positive for aCL antibodies. Serum MBL levels were significantly lower in the RHD group (median 4221 ng/ml versus 5166 ng/ml in healthy controls). AECA titres were correlated positively with patient age, duration of RHD and the severity of aortic stenosis, as determined by echocardiographic findings. In several autoimmune rheumatic diseases, such as systemic lupus erythematosus, vasculitis and scleroderma, AECA have been shown to play pathogenic roles by producing proinflammatory and procoagulant effects (increased expression of adhesion molecules and tissue factors, increased cytokine release) in endothelial cells. In RHD, these autoantibodies might represent a pathological link between activation of the valvular endothelium and valvular damage.

Biological and clinical effects of anti-TNFalpha treatment.

Tumor necrosis factor alpha (TNFalpha) is implicated in the pathogenesis of many chronic inflammatory diseases such as rheumatoid arthritis (RA), psoriasis and psoriatic arthritis (PsA), ankylosing spondylitis (AS), Crohn's disease, ulcerative colitis and uveitis. The availability of new pharmacological agents (infliximab, etanercept, adalimumab), able to selectively block the TNFalpha, has recently offered new opportunity for the treatment of these diseases. TNFalpha antagonists are different in the mechanism of action and are all effective agents in the treatment of RA and several chronic inflammatory diseases as a large number of controlled clinical trials have shown. Among biological effects of TNFalpha antagonists, the production of autoantibodies has been emphasized. This phenomenon is not correlated with the disease background, since anti-nuclear antibodies (ANA) and anti-double stranded-DNA antibodies (anti-dsDNA) induction is observed in RA as well as in spondyloarthritis (SpA) patients. Nonetheless, recent studies had reported a significant reduction in the serum titre of rheumatoid factor (RF) and/or anti-cyclic citrullinated peptide antibodies (anti-CCP) during anti-TNFalpha therapy. The TNFalpha antagonists represent a significant advance in the therapy of active RA and other chronic inflammatory diseases. However, they have distinct biological, clinical, and pharmacological properties that must be considered when selecting a drug for therapy.