Rheumatic heart disease (RHD) is usually characterized by the presence of anti-streptococcal group A antibodies and anti-endothelial cell antibodies (AECA). peptides recognized by serum cross-reactive antibodies were found through comparing the amino acid sequence of streptococcal antigens with human antigens. To investigate Anamorelin Fumarate 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. (GAS) pharyngitis in predisposed people . In 30-50% of cases recurrent episodes of ARF may lead to chronic rheumatic heart disease (RHD) with progressive and permanent damage of the cardiac valves . During the 20th century the improvement of living conditions and prevention guidelines have cut substantially the incidence and prevalence of ARF and RHD in industrialized countries. Nevertheless RHD remains one of the major causes of morbidity and mortality in developing countries. It is estimated that there are more than 15 million cases of RHD worldwide with 282?000 new cases and 233?000 deaths annually . Moreover a recent systematic echocardiographic screening revealed a prevalence of RHD that is approximately 10 occasions higher than that based on clinical screening . The endocardial valve tissue is the main localization of Rabbit polyclonal to PAK1. cardiac damage which begins when peripheral T lymphocytes reacting with adhesion molecules (i.e. vascular cell adhesion molecule 1 VCAM-1) infiltrate a non-vascularized tissue. The presence of anti-GAS antibodies is one of the major features and deposits of Anamorelin Fumarate antibodies and complement have been found in the heart of RHD patients [5 6 In a recent study in collaboration with Sana’a (Yemen) University we demonstrated the presence of anti-endothelial cell antibodies (AECA) in RHD patients . These antibodies have been demonstrated to play pathogenic functions in numerous autoimmune diseases in which endothelial damage is usually predominant [8 9 They Anamorelin Fumarate have proinflammatory and procoagulant effects on endothelial cells inducing up-regulation of adhesion molecule expression and increase of tissue factor (TF) and cytokine release [10 11 Molecular mimicry between GAS antigens and self-proteins is usually a hallmark of the pathogenesis of rheumatic fever [5 6 12 As rheumatic valve damage may begin on the surface of valvular endothelium AECA possibly using a mechanism of molecular mimicry could contribute to this damage by promoting endothelial stress. In the present study using immunoproteomic analysis we characterized the autoantibodies directed against endothelium in RHD patients and investigated the Anamorelin Fumarate presence of cross-reactivity between endothelial antigens and streptococcal antigens. Finally we evaluated the functional effects of cross-reactive antibodies on human microvascular cardiac endothelial cells (HMVEC-C). Materials and methods Patients and controls The study enrolled 140 consecutive patients (58 men 82 women age range 11-55 years) who were admitted to Al-Thawrah Hospital in Sana’a Yemen for RHD described previously . All patients were diagnosed according to the altered Jones criteria . One hundred and forty sex-and age-matched normal health subjects enrolled as.