Study Follows Spaceflight Effects on Mouse Microbes, Metabolites Associated With Bone Density

In a paper appearing in Cell Reports, a team from the University of California, Los Angeles, the Forsyth Institute, and other centers track gut microbe, blood serum metabolite, and bone mineral density features in mice exposed to spaceflight. As part of NASA's Rodent Research 5 (RR-5) mission, the investigators used targeted 16S ribosomal RNA sequencing and metagenomic sequencing to track microbial representatives and microbial gene collections in fecal samples from 20 female mice sent to space at the age of 30 weeks old. When they analyzed microbiome patterns in the 10 animals that returned to Earth after more than a month on the International Space Station and those that remained in space to one another and to baseline samples, the authors saw a microgravity-associated rise in Lactobacillus murinus microbes and bugs from the Dorea genus, as well as enhanced representation of microbial genes in pathways that produce metabolites found at higher-than-usual levels in liquid chromatography-tandem mass spec profiled blood samples from space-exposed mice such as lactic acid, glutathione, and leucine/isoleucine. "These metabolites are elevated in the microgravity-exposed host serum," the authors report, adding that ELISA "reveals increases in osteocalcin and reductions in tartrate-resistant acid phosphatase 5b signifying additional loss of bone homeostasis in flight."