Th17 cells and human arthritic diseases

Th17 cells, though having been discovered just few years ago, is believed as the pathogenic T cells in many autoimmune diseases and chronic inflammatory diseases, such as rheumatoid arthritis (RA). Biologics targeting IL-17 have already been on clinical trial, and the results were recently reported. Although the importance of Th17 cells in animal models of arthritis is unquestionable, it is not recognized that there are only limited data on the role of Th17 cells and related cytokines in human arthritic diseases. In addition, the characteristics of human Th17 cells have not been fully defined, and there seem to be substantial differences between human and mouse Th17 cells. In this review, I will introduce and discuss about updated findings on human Th17 cells and its relation with human arthritic diseases.