Autoimmune connective tissue diseases in the COVID-19 pandemic.

Autoimmune connective tissue diseases are a heterogeneous group of clinical entities sharing a common feature-an impairment of structural components like collagen and elastin, arising by autoimmune mechanisms. Because most patients are on a long-term immunosuppressive therapy, which renders them vulnerable to infections, a new challenge appears in front of physicians in the coronavirus disease 2019 (COVID-19) era. Immune mechanisms are substantial for the control and ceasing of viral infections, and their impairment may cause serious complications; however, data from immunosuppressed transplant patients do not reveal a higher frequency or diseases' severity in those infected by COVID-19. Several immunotherapies used to treat autoimmune connective tissue diseases favorably modulate the immune response of severe acute respiratory syndrome coronavirus (SARS-CoV-2)-infected patients. The present review highlights the problems of susceptibility, severity, and therapeutic options in patients with autoimmune connective tissue diseases during the COVID-19 pandemic. The relationship between autoimmune connective tissue diseases and COVID-19 infection is explained with antiviral protection genes expression, hypercytokinemia, and lymphohistiocytosis/macrophage activation mechanisms. Recommendations concerning therapy for prevention during the pandemic period or in case of concomitant COVID-19 infection are also presented. Clinical trials are ongoing regarding COVID-19 therapy blocking the cytokine response. © 2021 Elsevier Inc. All rights reserved.