Interleukin-6 Blocking Therapy for COVID-19: From Immune Pathogenesis to Clinical Outcomes

As a newly emerged infectious disease, the coronavirus disease 2019 (COVID-19) has caused millions of deaths, resulting in a global health challenge. Currently, several vaccines have been approved with significant benefits against disease transmission. However, effective therapies are still needed for the clinical management of infected COVID-19 patients. Available evidence has indicated elevated levels of proinflammatory cytokines, including interleukin-6 (IL-6), in COVID-19 patients, with cytokine storm involving excessive cytokine release being observed in some severe cases. Several clinical studies have shown the promising effects of IL-6-blocking strategy in treating severe COVID-19 patients, but some observational studies have reported that IL-6-blocking therapy has no effects in preventing disease progression or death among COVID-19 patients. Herein, we review recent findings on the immunopathogenesis of COVID-19, with specific emphasis on the proinflammatory function of IL-6 and discuss the therapeutic potential of IL-6-blocking therapy for the treatment of COVID-19 patients, especially those with rheumatic diseases.