CCR2 and acute respiratory distress syndrome: CCL2 is up-regulated into the lungs of patients with ARDS, which then induces the migration of circulating CCR2 positive inflammatory cells into the alveoli; airways of patients with COVID-19 express pro-inflammatory mediators, including CCL2; airway myeloid cells propagating inflammatory responses in COVID-19 is further supported by the excessive CCL2 levels found in airways, but not blood in COVID-19 patients versus healthy controls [3,110].