LEP and rheumatoid arthritis: The connection between leptin and the JAK-STAT system is especially interesting since studies have shown better effect on pain in RA-patients with JAK inhibitors such as Baricitinib (JAK 1 and 2 inhibitor) than with adalimumab, possibly through changes in activation of microglia in the spinal cord and suppression of the JAK/STAT system in the dorsal root ganglia [28–30].