Biomarkers of pulmonary fibrosis in COVID-19 and postcovid syndrome

COVID-19 can occur in the form of an acute respiratory viral infection of a mild course, or in a severe form. Both effective treatments for the acute phase of the disease and the clinical and functional long-term consequences of COVID-19, which include the complexity of symptoms and organ damage referred to as «long-term COVID» or «post-acute COVID-19 syndrome», are attracting interest in the medical community. The term «post-acute COVID-19 syndrome» has been proposed to refer to symptoms and/or abnormalities that are not related to another cause, persist or are present after four weeks of the diagnosis of the disease. One of the key components of the post-acute COVID-19 syndrome, which can lead to serious complications of the clinical course in patients, is considered to be pulmonary fibrosis, which is a pathological outcome of chronic and acute interstitial lung disease. COVID-19 itself is relatively new disease, which makes it difficult to study the course of the pathological process. To analyze the pathogenesis, multiple studies were conducted on patients who had been ill with various forms of COVID-19. After the disease, the body can begin both the normal process of regeneration of lung tissue and its distortion, leading to severe complications and long-term restoration of normal functioning of the whole organism. In pulmonary fibrosis, the number of deaths is much higher, which is why biomarkers of this outcome have been developed in order to reduce the number of deaths from the COVID-19 complication. The review is devoted to the epidemiology, pathogenesis, histopathology of pathological flora in COVID-19, postcovid syndrome and biomarkers that can identify patients with an increased likelihood of developing the disease. The purpose of this review is to describe various pathogenic hypotheses that have been formulated in order to explain the development of pulmonary fibrosis, the study of acute phases associated with biomarkers that could suggest the onset of fibrotic lung lesions.

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