HMGB1 and acute respiratory distress syndrome: The plasma level of high mobility group box 1 protein (HMGB1), one of the damage-associated molecular pattern molecules (DAMPs), has been found to correlate with excessive cytokine storm and severity of tissue damage in patients with severe pneumonia or ARDS.4 HMGB1 initiates inflammation in COVID-19 patients via at least two separate pathways.