How JAK Inhibitors Work

JAK inhibitors work by blocking the activity of Janus kinases (JAKs), a family of enzymes that are involved in the signaling pathways of various cytokines and growth factors. Cytokines are small proteins that regulate cellular activities and immune responses, while growth factors promote cell growth and differentiation.

JAKs are activated when they bind to specific cytokines or growth factors, leading to the phosphorylation of downstream signaling molecules called signal transducers and activators of transcription (STATs). STATs then translocate to the nucleus, where they regulate the expression of various genes involved in immune responses, inflammation, and cell growth.

JAK inhibitors block the activation of JAKs by preventing their phosphorylation, thereby inhibiting the downstream signaling cascade and ultimately reducing the production of inflammatory mediators and the proliferation of certain immune cells. This interference with JAK-STAT signaling makes JAK inhibitors effective in treating conditions characterized by excessive immune responses and inflammation, such as rheumatoid arthritis, inflammatory bowel disease, and certain types of cancer.

Some examples of JAK inhibitors include tofacitinib (Xeljanz), baricitinib (Olumiant), and ruxolitinib (Jakafi), which are commonly used to treat rheumatoid arthritis and other immune-mediated disorders. They are typically administered orally and can be used alone or in combination with other medications.