Immunopathology of SARS-CoV-2 infection

The loss of human life as well as the global economic costs because of COVID-19 are devastating. Despite having effective diagnosis, antiviral treatment, and vaccines to prevent infection, it is essential to delve deeper into the pathogenic mechanisms in the SARS-CoV-2 virus and its recent variants infection. Despite advances, the understanding of the pathobiology of COVID-19 remains incomplete, particularly due to the emergence of SARS-CoV-2 variants, with augmented transmissibility and pathogenicity. The analysis of the host immune responses in lung and other tissues induced by this virus has allowed us to partially understand the pathogenesis of severe forms of COVID-19, and distinguish it from other respiratory infections. The complex interaction between cytokines, other immune mediators and viral factors results in exacerbated, poorly regulated, inflammation which contributes to tissue damage and the appearance of severe forms of the disease. In this review, we provide an overview of the immunological mechanisms in SARS-CoV-2 infection and their role in severe disease. We analyzed the role of matrix metalloproteinases, transforming growth factor beta and other key immunological mediators in lung damage. Furthermore, we discuss their possible implications in the post-COVID-19 sequelae and highlight the study of these molecules as biomarkers for the diagnosis, prognosis and treatment of convalescent patients with COVID-19.