1. Innate immunity in coronavirus infection
- Author
-
V. S. Smirnov and Areg A. Totolyan
- Subjects
0301 basic medicine ,ARDS ,viruses ,Immunology ,mers-cov ,coronavirus ,Infectious and parasitic diseases ,RC109-216 ,medicine.disease_cause ,03 medical and health sciences ,0302 clinical medicine ,sars-cov ,Immunology and Allergy ,Medicine ,Respiratory system ,innate immunity ,Coronavirus ,Innate immune system ,intracellular regulatory cascade ,business.industry ,virus diseases ,Pulmonary edema ,medicine.disease ,cytokines ,respiratory tract diseases ,interferons ,sars-cov-2 ,030104 developmental biology ,Infectious Diseases ,medicine.anatomical_structure ,030220 oncology & carcinogenesis ,Middle East respiratory syndrome ,business ,Cytokine storm ,Respiratory tract - Abstract
Coronaviruses (CoVs) comprise a polymorphic group of respiratory viruses causing acute inflammatory diseases in domestic and agricultural animals (chicken, pig, buffalo, cat, dog). Until recently, this infection in humans was mainly observed during the autumn-winter period and characterized by a mild, often asymptomatic, course. The situation changed dramatically in 2003, when SARS outbreak caused by pathogenic CoV (SARS-CoV) was recorded in China. A decade later, a new CoV outbreak occurred in the form of the Middle East respiratory syndrome (MERS-CoV), whereas in December 2019, SARS-CoV-2 (COVID-19) cases were recorded, which transformed within the first months of 2020 into the pandemic. In all three cases, CoV disease led to severe bronchopulmonary lesions, varying from dry, debilitating cough to acute respiratory distress syndrome (ARDS). At the same time, multiple changes in innate immunity were noted most often manifested as a pronounced inflammatory reaction in the lower respiratory tract, featured by damaged type II pneumocytes, apoptosis, hyalinization of alveolar membranes, focal or generalized pulmonary edema. Destructive processes in the respiratory tract were accompanied by migration of monocytes/macrophages and granulocyte neutrophils to the inflammatory focus. Such events were accompanied by production of pro-inflammatory cytokines, which magnitude could ascend up to a cytokine storm. SARS-CoV is characterized by symptoms of secondary immunosuppression, manifested by the late onset of interferon production and activation of NLRP3 inflammasomes – the key inflammatory factor. The reason for such reaction may be accounted for by CoV arsenal containing extensive set of structural and non-structural proteins exerting pro-inflammatory and immunosuppressive properties. Delayed IFN production allowed CoV to replicate actively and freely, and when type I IFN synthesis was eventually triggered, its activity was detrimental and accompanied by an aggravated infection course. Thus, SARS can surely be referred to immune-dependent infections with a marked immunopathological component. The purpose of this review was to describe some mechanisms underlying formation of innate immune response to infection caused by pathogenic coronaviruses SARS-CoV, MERS-CoV and SARS-CoV-2 (COVID-19).
- Published
- 2020