The role of T helper ۹(Th۹) against Infectious Diseases

Background and aims: Infectious diseases are disorders caused by organisms such as bacteria, viruses, fungi or parasites .The Th۹ subset develops in response to combined signals from TGF-b and IL-۴ among a cacophony of other cytokines in an extracellular milieu. T helper ۹ (Th۹) cells,  as a novel CD۴ T cell subset, seem to play a complex role in the outcome of specific immune responses. In this article, we aimed to review the role of these cells in infectious disease. Methods: In this mini-review study, we study ۲۵ novel articles since ۲۰۰۹ to ۲۰۱۴ about the role of T helper ۹ in some Infectious Diseases. Results: Pleural mesothelial cells promoted Th۹ cell differentiation by presenting antigen. It significantly differentiated Th۱۷, but not Th۹ cells in the development of CVB۳-induced VMC. The microenvironment of VMC seemed to contribute to the differentiation and proliferation of Th۱۷ rather than to differentiation of Th۹ cells. Having reviewed the limited number of articles considering this relevance, we came to this result that Lymphatic Filariasis and mycobacterium tuberculosis infections confirmed the existence of such relationship. In addition, Rapamycin resistant murine Th۹ cells have a stable in vivo phenotype and inhibit graft-versus-host reactivity but concerning Viral Myocarditis, Th۹ cells could not protect against it. Conclusion: The accurate molecular mechanisms underlying the generation and differentiation of human Th۹ cells are not elucidated completely. Th۹ cells exhibit  Ag specific expansion in a chronic helminth infection (lymphatic filariasis), but in relevance to viral myocarditis, Th۹ cells did not play an efficient role against it. However; knowing that whether Th۹ cells participate in the protection against infections needs further research.

Keywords:

T helper ۹ , Infections , Helminthes , Mycobacterium tuberculosis