The Role of IL-17 in COVID-19

Interleukin 17A belongs to the interleukin 17 family and is a pro-inflammatory cytokine produced by the T-helper 17 cell, a known special subset of specialized CD4+ in the production of pro-inflammatory cytokines (Zenobia, 2015). Interleukin 17A has been seen to be a significant cause of acute respiratory distress syndrome (ARDS) in COVID-19. IL-6, IL-1b and tumor growth factor b are all required for TH17 differentiation in humans (Shibabaw, 2020) and notably, IL-6 – as discussed in our previous blog post, has also been seen to contribute to ARDS in COVID-19. The presence of IL-17 can serve as a biomarker to the severity of the disease, in those with severe covid-19 their APC are seen to release IL-6 and IL-23 (Shibabaw, 2020). If TGF- b1 is used to differentiate naïve CD4+ T-Cells, then the presence of IL-6 and IL-23 can induce the IL-17 to become autoimmune. As a result of the considerable amounts of IL-17 being produced, there is an increase in NK-kB activity and a decrease in Interferon 1 production – both of which contribute to the cytokine storm seen in COVID-19 (Shibabaw, 2020).

In COVID-19 the cytokine storm is the main culprit that results in the symptoms we see SARS-CoV-2 has. We are now seeing many therapeutic effects with cytokine inhibitors or immunomodulatory therapies. By blocking interleukin 17 itself or in the downstream and upstream signalling pathways, such as with interleukin 6, we can see the downregulation of IL-17 and its inflammatory effects (Mendoza, 2020). Those with severe COVID-19, as well as in the related coronaviruses such as SARS and MERS, a large spike in TH17 and IL17 levels are seen. This type of treatment has already shown to have positive results with tocilizumab in blocking the IL-6 receptor which was able to quickly manage the symptoms of ARDS (Mendoza, 2020). While this type of treatment has shown to be effective with certain pro-inflammatory cytokines, the negative implications are that it is unknown what blocking certain cytokines may result in. Since cytokines play a key function in the clearance of pathogens, depending on which cytokines are inhibited one may see detrimental effects to the immune system’s ability to clear out or handle SARS-CoV-2.  

        Reddot Biotech is pleased to offer several ELISA Kits from the interleukin 17 family in both our traditional and Ready-To-Use formats. For more information and to see the product manuals, visit the product page for RD-IL17-Hu and RDR-IL17-Hu. If you have any other questions, please feel free to contact us.

References and further reading:

1. Mendoza, V. M. M. (2020, June 3). Interleukin-17: A potential therapeutic target in COVID-19. The Journal of infection. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7834707/. 

2. Shibabaw, T. (2020, October 6). Inflammatory Cytokine: IL-17A Signaling Pathway in Patients Present with COVID-19 and Current Treatment Strategy. Journal of inflammation research. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7547786/. 

3. Zenobia, C., & Hajishengallis, G. (2015, August 7). Basic biology and role of interleukin-17 in immunity and inflammation. Periodontology 2000. https://www.ncbi.nlm.nih.gov/p...;

4. Pacha, O., Sallman, M. A., & Evans, S. E. (2020, May 1). COVID-19: a case for inhibiting IL-17? Nature News. https://www.nature.com/article...;