Immunity system complexity: macrophages repair lungs (Introduction)

by David Turell , Wednesday, October 09, 2024, 17:59 (45 days ago) @ David Turell

Newly found:

https://mail.google.com/mail/u/0/#inbox/FMfcgzQXJZsNsSCMXzccGPLGbzdxznnK

"Initially mistaken for neutrophils, a population of atypical macrophages appears in the lungs after severe viral infection, orchestrates tissue repair, and then vanishes.

***

"Monocyte-derived macrophages recruit to the lungs en masse during the short window immediately following viral infection, so Marichal and his colleagues were at a loss as to why they appeared in such large numbers in the lungs of people who had already recovered from the virus.

***

"Now, in a recent Science Immunology study, Marichal and his colleagues confirmed that these unusual cells that emerged following an IAV infection are macrophages, and that they facilitate the repair of alveoli in the lungs following severe viral infections in mice. The findings highlight a novel population of macrophages that could be targeted therapeutically to treat lung damage.

***

"Subsequent single-cell RNA sequencing and transmission electron microscopy experiments further confirmed that the Ly6G+ macrophages were distinct from neutrophils. During severe respiratory illness, such as COVID-19 or IAV, Marichal said, lungs sustain patches of damage to the alveoli, impairing gas exchange. Once the infection has been cleared, the lesions are repaired by progenitor cells, which differentiate into epithelial cells that form new alveoli. Using confocal microscopy to peer into the lungs of mice that had cleared IAV infections, the team found Ly6G+ macrophages located near the damaged tissue in the space between the alveoli, where they clustered with progenitor cells. The team hypothesized that the Ly6G+ macrophages were orchestrating damage repair by giving instructions to the progenitor cells.

"Further experiments confirmed that Ly6G+ macrophages release soluble factors that instruct the progenitor cells to proliferate and differentiate. They found that this function was partly dependent on signaling via the interleukin-4 (IL-4) receptor, which is known to induce a repair phenotype in other macrophages.

"To explore the full capabilities of these interesting cells, the team turned their attention to other types of injury and different organs. They found that Ly6G+ macrophages repair the lungs and liver of mice after drug-induced injuries as well. The team also showed that monocyte-derived macrophages present in samples of lung fluid from humans with suspected pneumonia are transcriptionally similar to Ly6G+ macrophages in mice."

Comment: an amazing group of cells like teams from FEMA in the USA doing emergency management in storm-battered areas. The cells act with purpose and this is more evidence for design.