Background: Sarcopenia is the loss of skeletal muscle mass and strength, and affects up to 70%
of patients with cirrhosis. Since many mammals survive hibernation without muscle
loss, they are often studied in the context of sarcopenia. It was shown that the abundance
of urease-producing bacteria is increased in squirrels during hibernation and that
the nitrogen produced is integrated into muscle protein. Due to this finding, we aimed
to gain a better understanding of nitrogen recycling potential in sarcopenia with
a special focus on sex-specific differences since cirrhosis and sarcopenia have a
male predominance.
Materials and methods: Stool samples of 152 patients (96 cirrhotics, 56 non-cirrhotics) with and without
sarcopenia were obtained. We predicted the functional profiles of microbial communities
based on 16S rRNA sequencing data (Tax4Fun2) and extracted the predicted abundance
of urease subunits (alpha, beta, gamma). Additionally, we performed a systematic literature
search to identify urease-producing taxa and extracted their abundance from 16S rRNA
sequencing data to compare them between patients with and without sarcopenia
Results: Sarcopenia, but not cirrhosis nor sex was associated with lower urease gene abundance.In
women irrespective of cirrhosis (n=49; 28 sarcopenic) and in patients with cirrhosis
(n=64; p<0.05) gene abundance of urease subunits was lower in sarcopenic patients,
irrespective of sex. The systematic literature search yielded 120 taxa, of which 35
were present in sequencing data. Overall abundance of potentially urease-producing
taxa was comparable between the groups with only slight and divergent differences
in abundance of Bacteroides fragilis, Micrococcaceae and Clostridiaceae 1 .
Conclusions: We found lower levels of predicted urease gene abundance in patients with sarcopenia.
This gives the first indications for the potential role of the gut microbiome and
the potential for nitrogen recycling in sarcopenia. More pronounced differences in
women and patients with cirrhosis, two groups disproportionally affected by sarcopenia,
point towards a potential precision medicine target.
