Sodium butyrate ameliorates intestinal motility and is associated with enteric neuroimmune changes in slow transit...

The pathogenesis of slow transit constipation (STC) is still not fully elucidated, and there are no related specific drugs currently available for clinical use. Therefore, our study combined 16S ribosomal RNA (rRNA) gene sequencing, untargeted metabolomics, transcriptomic analysis, and a mouse intervention model to characterize the alterations associated with STC and to evaluate the effects of sodium butyrate (NaB).

16S rRNA gene sequencing, untargeted metabolomics, and RNA sequencing (RNA-seq) were performed in human samples. A loperamide-induced STC mouse model was established to evaluate the effects of NaB. Colonic tissues were assessed using hematoxylin-eosin (H&E) staining, Alcian blue staining, and immunohistochemistry, whereas longitudinal muscle and myenteric plexus preparations were used for immunofluorescence and quantitative reverse transcription PCR (qRT-PCR) analyses.

There were 16 differential bacterial genera between patients with STC and healthy donors. Untargeted metabolomics identified 71 exploratory candidate metabolites meeting variable importance in projection (VIP) > 1 and nominal p < 0.05. A total of 2,825 differentially expressed genes (DEGs) were identified. Pathway-level comparison of the independent metabolomic and transcriptomic datasets identified butanoate metabolism as one of the exploratory overlapping pathways. In vivo, we found that NaB improved the fecal parameters of STC mice. NaB treatment was accompanied by increased CD206-associated macrophage signals and reduced expression of the pro-inflammatory cytokines in the enteric nervous system (ENS) microenvironment. The number of HuC/D-positive neurons was increased, and the number of HuC/D-positive neurons co-expressing cleaved caspase-3 decreased following NaB treatment. Furthermore, the number of HuC/D-positive neurons co-expressing pSTAT3 decreased following NaB treatment.

NaB improved the constipation-related phenotypes in loperamide-induced STC mice and was accompanied by reduced inflammatory features, decreased myenteric neuronal apoptosis, and reduced neuronal pSTAT3 staining in the ENS. These findings suggest that the beneficial effects of NaB may be associated with the modulation of the enteric neuroimmune microenvironment.