Pathologie diagnostique : accès libre

Abstrait

A Review on COVID-19 Severity from the Point of Radiological Findings and Host Immunity including Microbiome: Mini-Review

Nobuhiro Asai, Hiroshige Mikamo

Background: The pandemic of coronavirus infection 2019 (COVID-19) causes not only a health and economic crises, but also reveals a human relations problem such as racism and a conflict between nations. In Japan, we face several problems; The Tokyo Olympics 2020 was postponed to 2021, the emergence of social distancing enforcers, discrimination against medical staff who provide medical care for the patients with COVID-19 and misleading information by the mass media regarding COVID-19 vaccines. COVID-19 is not solely a viral disease, but a social problem that is caused by other factors. Because it is a social problem, the mechanism of disease severity in COVID-19 is multifactorial, complicated and is affected by viral pathogenesis as well as by host immunity. We describe the review focusing on the multiple factors which could cause disease severity of COVID-19.

Main text: All respiratory viruses could cause viral pneumonia, even though the frequency and severity depend on the virus itself. The mortality rate of COVID-19 differs in different ages as well as radiological findings in different age. It is well-known that radiological findings differ in host immunity, such as Pneumocystis jirovecii pneumonia (PJP), Mycoplasma pneumoniae pneumonia. These are affected by the imbalance of cytokine produced between type I and II of helper T-cell, showing a different prognosis. As for disease severity of COVID-19, there are several theories that COVID-19 patients show different radiological patterns and outcomes by age. Not only viral pathogenesis but also dysfunction of monocytes in aging and the lung and the gut dysbiosis could contribute to the high mortality rate in elderly patients.

Conclusion: Viral immunity affected by lung and gut dysbiosis and age-associated monocyte dysfunction could cause disease severity in humans. We hypothesize that radiological findings and prognosis of COVID-19 differ by aged-group.