Fig. 2.

Induction of inflammatory process and production of an immune response. The patterns are recognized by neighboring epithelial cells, endothelial cells, and alveolar macrophages, which initiate the production of pro-inflammatory cytokines and chemokines (including IL-6, IP-10, inflammatory protein macrophage 1a (MIP1α), MIP1β and MCP1). Immediately monocytes, macrophages, and T cells are attracted to pro-inflammatory proteins, initiating localized inflammation, with the production of IFNγ by T cells. In some situations, an additional accumulation of immune cells in the lungs can occur, causing a storm of pro-inflammatory cytokines, which damage the pulmonary infrastructure and other organs. A balanced immune response occurs as follows: the initial inflammation attracts specific T cells, which can attack the virus and eliminate infected cells. The production of neutralizing antibodies helps to block viral infection, reducing the associated risks. Finally, alveolar macrophages initiate a coordinated attack on neutralized viruses and apoptotic cells and eliminate them by phagocytosis. The process reduces viral load and damage to the lungs, resulting in faster recovery.