CSF2 and rheumatoid arthritis: IL-6 or Janus kinase (JAK) inhibitors were reportedly efficacious against COVID-19 in the clinical setting, and they have also been used in RA therapy.[8] In the late phase of COVID-19, the cytokine storm is the main cause of lung injury, and several immune factors, such as IL-6, JAK1/2, and GM-CSF, were reportedly common signaling cascades, like those in RA.