Key Role of Mesenchymal Stromal Cell Interaction with Macrophages in Promoting Repair of Lung Injury

Lung macrophages (M phi s) are essential for pulmonary innate immunity and host defense due to their dynamic polarization and phenotype shifts. Mesenchymal stromal cells (MSCs) have secretory, immunomodulatory, and tissue-reparative properties and have shown promise in acute and chronic inflammatory lung diseases and in COVID-19. Many beneficial effects of MSCs are mediated through their interaction with resident alveolar and pulmonary interstitial M phi s. Bidirectional MSC-M phi communication is achieved through direct contact, soluble factor secretion/activation, and organelle transfer. The lung microenvironment facilitates MSC secretion of factors that result in M phi polarization towards an immunosuppressive M2-like phenotype for the restoration of tissue homeostasis. M2-like M phi in turn can affect the MSC immune regulatory function in MSC engraftment and tissue reparatory effects. This review article highlights the mechanisms of crosstalk between MSCs and M phi s and the potential role of their interaction in lung repair in inflammatory lung diseases.

Automated summary

Lung macrophages play a crucial role in pulmonary innate immunity and host defense. The interaction between these macrophages and mesenchymal stromal cells (MSCs) has shown potential in treating inflammatory lung diseases and COVID-19. The lung microenvironment facilitates the secretion of factors by MSCs, leading to polarization of macrophages towards an immunosuppressive M2-like phenotype for tissue repair. In turn, M2-like macrophages can affect the immune regulatory function and tissue reparatory effects of MSCs.