Th17 and treg cells in the pathogenesis of rheumatic heart disease

Rheumatic fever is an autoimmune disease which is the late complication of infection of the upper respiratory tract by group A ß hemolytic streptococci. It?s main targets are heart, joints, central nervous system, skin and subdermal tissues.Involvement of the organs other than heart is temporary and resolves without a residue, however, rheumatic carditis may cause chronic rheumatic heart disease.Chronic rheumatic valve disease is a considerable cause of mortality and morbidity in our country. Pharyngitis caused by group A ß hemolytic streptococci, when not treated or undertreated, may cause acute rheumatic fever in 3% of thesubjects. It is difficult to explain "this? by only the high virulence or frequency of streptococci that are potentially rheumatogenic. Although the virulence mechanisms of the group A treptococcus bacteria is investigated in detail,humoral and cellular basis of the immune response directed against this organism is not ?known? sufficiently. ?This? averts the effective therapy being developed against the autoimmune response associated with group A ß hemolyticstreptococci.Th17 and Treg cells are considered important in the pathogenesis of many autoimmune disease. It has been showed that Th17 cells are being increased while Treg cells are decreased in diseases with an autoimmune etiology. IncreasedTh17/Treg ratio triggers an uncontrolled inflamatory reaction to a specific antigen which ends up in autoimmunity. Our aim in this study is to investigate the role of these cells in the immunopathogenesis of rheumatic heart disease.In mitral stenosis, which is the most frequent form of rheumatic heart disease, it is shown that peripheral Th17 cells are increased while Treg cells are decreased and the ratio of Th17/Treg ratio is significantly increased, whencompared to healthy individuals. High hsCRP levels seen in patients with rheumatic heart disease points to the ongoing inflammation. Besides, positive correlation seen between serum hsCRP levels and Th17/Treg ratio points out that Th17 and Treg cells may play a role on the ongoing low level inflammation inrheumatic heart disease.Key words: Rheumatic heart disease, mitral stenosis, Th17/Treg ratio