Old wine in new wineskins. Hamman-rich syndrome has much in common with severe COVID-19: Do they share any link of pathogenesis or depend on the similar aetiological factor(s)?

Abstract

For the first time the acute interstitial pneumonitis as a main cause of adult idiopathic respiratory distress syndrome was described in 1933–35 by the American medical scholars Louis Virgil Hamman and Arnold Rice Rich as “acute fibrosing alveolitis” later given the eponymous name Hamman-Rich syndrome. This disease targets the interstitium of the lungs and characterized by fulminant onset, acute respiratory disorder with possibility of respiratory failure, being clinically similar to respiratory distress syndrome with the pathomorphologically revealed diffuse alveolar damage. Hamman-Rich syndrome is characterized by rapid progression from symptoms of common cold such as cough, fever, chills and dyspnea to severe respiratory failure. The syndrome affects apparently healthy individuals and is not associated with any anamnestic chronic lung diseases, smoking habits, neither with patients’ age or sex. The aetiology and pathogenesis of the Hamman-Rich syndrome are not clear yet. The familiar genetic predisposition is of definite meaning, especially related to mutations of surfactant proteins and their metabolism. The possible mechanistic links of this fulminant lung disease involve: NK-cells, auto-aggressive immune activation and certain types of cytokines during their excessive systemic action, so-called cytokine storm (e.g. interleukin-18 and interleukin-2), which play the leading part in the pathogenesis of acute lung cell injury resulting in diffuse non-remitting pneumofibrosis. But all these clinical and pathogenetic features are also common for severe COVID-19. Computed tomography is used for instrumental diagnosis of Hamman-Rich syndrome and also gives the lung images quite similar to that of COVID-19, including ground glass opacity symptoms. The authors hypothesize that the same link(s) of pathogenesis underlie the severe course of COVID-19 and Hamman-Rich syndrome. It is possible that cases of Hamman-Rich syndrome were due to the circulation in populations of a less virulent, unrecognized coronavirus, which interacts with the immune system of genetically susceptible individuals in a way similar to SARS-CoV2. For sure, the identification of the characteristics of the genome of patients with Hamman-Rich syndrome will shed light on the genetic mechanisms that predispose to the severe course of COVID-19 and vice versa — the experience of severe COVID-19 treatment can be applied to the therapy of Hamman-Rich syndrome as well.