Janus kinases and signal transducers and activators of transcription: their roles in cytokine signaling, development and immunoregulation

Cytokines play a critical role in the normal development and function of the immune system. On the other hand, many rheumatologic diseases are characterized by poorly controlled responses to or dysregulated production of these mediators. Over the past decade tremendous strides have been made in clarifying how cytokines transmit signals via pathways using the Janus kinase (Jak) protein tyrosine kinases and the Signal transducer and activator of transcription (Stat) proteins. More recently, research has focused on several distinct proteins responsible for inhibiting these pathways. It is hoped that further elucidation of cytokine signaling through these pathways will not only allow for a better comprehension of the etiopathogenesis of rheumatologic illnesses, but may also direct future treatment options.