- Interleukin 6 (IL-6) plays a role in inflammation
- When binded to receptors on target cells of the virus, inflammation in the lungs and other organs occur
- Tocilizumab (an antibody) can bind to the receptor IL-6; this prevents IL-6 from binding with the target cells and causing inflammation. It is an inhibitor of both membrane-bound and soluble IL-6, thus allowing inhibition both cis and trans transduction pathways of IL-6.


Michigan State University

Boston University

- Patients with severe cases of COVID-19 were given tocilizumab
- Tocilizumab lowered the patients’ body temperature, this returning the fever to normal (after 1 day)
- 15/20 patients required less oxygen therapy (after 5 days)
- The lymphocyte count (in peripheral blood) in about half the patients returned to the normal range
- Lowered C-reactive protein to a safe level in 16/19 patients
- All the patients were discharged after approximately 15 days


Severe COVID-19 cases and the impact of tocilizumab

IL-6 cytokines bind to IL-6 receptors (IL-6Rs) on cell surfaces.  The protein gp130 found within the receptor transmits the cytokine's signal and prompts janus kinases (JAKs) to come to the IL-6R.  These kinases phosphorylate the receptor as well as themselves which ultimately leads to the phosphorylation and dimerization of the protein Stat3.  Stat3 dimers move into the nucleus and bind to the IFNγ active site of genes related to inflammation and intracellular adhesion as a transcription factor.   

IL-6 Family Signaling Pathway

Xu, X., Han, M., Li, T., Sun, W., Wang, D., Fu, B., ... & Zhang, X. (2020). Effective treatment of severe COVID-19 patients with tocilizumab. Proceedings of the National Academy of Sciences, 117(20), 10970-10975.

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