Georgia State College (GSU) researchers report that the susceptibility of mice to respiratory virus infections (RVIs), in addition to the infections’ severity, relies upon at the very least partially on the microbiota of their intestines.
The researchers measured viral concentrations within the lungs a number of days after an infection to evaluate how variations in microbe combine can affect RVI outcomes in mice with completely different intestinal microbiomes and in these differing solely within the presence or lack of segmented filamentous micro organism (SFB). The mice had been bred in captivity below well-controlled circumstances that ensured the absence of particular microbes.
The findings had been revealed yesterday in Cell Host & Microbe.
SFB are gram-positive, spore forming micro organism discovered within the intestine of rodents, fish, and chickens. A relative of Clostridium, these micro organism have been discovered to set off an immune response in mice.
Lung macrophages disabled flu virus
Whether or not naturally acquired or launched, SFB protected mice towards flu, respiratory syncytial virus (RSV), and SARS-CoV-2 an infection (COVID-19). The safety required the presence of alveolar macrophages (AMs; immune cells) within the lungs at baseline. In mice with out SFB, AMs had been rapidly depleted as RVI progressed, however AMs in SFB-positive mice had been intrinsically altered to stop flu-triggered depletion and inflammatory signaling.
These findings uncover complicated interactions that mechanistically hyperlink the intestinal microbiota with AM performance and RVI severity.
AMs immediately disabled influenza virus, and switch of SFB-transformed AMs into SFB-negative mice bolstered SFB-mediated safety towards flu.
“These findings uncover complicated interactions that mechanistically hyperlink the intestinal microbiota with AM performance and RVI severity,” the research authors wrote.
Andrew Gewirtz, PhD, co-senior writer and regents’ professor within the Institute for Biomedical Sciences at GSU, mentioned the group thinks it’s extremely unlikely that SFB is the one intestine microbe that may alter AMs, and consequently, vulnerability to RVI.
“Somewhat, we hypothesize that intestine microbiota composition broadly influences proneness to respiratory virus an infection,” he mentioned in a GSU information launch. “Microbiota mediated programming of basally resident alveolar macrophages could not solely affect the severity of acute respiratory virus an infection, however can also be a long-term post-respiratory virus an infection well being determinant.”