Short bowel syndrome (SBS) is a condition that results from a reduction in the length of the intestine or its functional capacity. SBS patients can have significant side effects and complications, the etiology of which remains ill-defined. Thus, facilitating intestinal adaptation in SBS remains a major research focus. Emerging data supports the role of the gut microbiome in modulating disease progression. There has been ongoing debate on defining a “healthy” gut microbiome, which has led to many studies analyzing the bacterial composition and shifts that occur in gastrointestinal disease states such as SBS and the resulting systemic effects. In SBS, it has also been found that microbial shifts are highly variable and dependent on many factors, including the anatomical location of bowel resection, length, and structure of the remnant bowel, as well as associated small intestinal bacterial overgrowth (SIBO). Recent data also notes a bidirectional communication that occurs between enteric and central nervous systems called the gut–brain axis (GBA), which is regulated by the gut microbes. Ultimately, the role of the microbiome in disease states such as SBS have many clinical implications and warrant further investigation. The focus of this review is to characterize the role of the gut microbiota in short bowel syndrome and its impact on the GBA, as well as the therapeutic potential of altering the microbiome.

Background/Objectives: Females are generally more resistant to ischemia-related ferroptosis than males, due to differences in iron metabolism, antioxidant pathways, and sex hormone-mediated regulation of ferroptosis suppressors. This has not been systematically studied in a human donor liver model. To investigate the effect of sex on ferroptosis and oxidative stress pathways in non-utilized donor livers (NDLs), we assessed patterns of gene expression in NDLs under ex vivo normothermic machine perfusion (NMP). Methods: We utilized the PROTECT dual-circuit ex vivo NMP system to assess three male and two female NDLs undergoing 6 h NMP. Perfusate and tissue samples were collected at baseline and 6 h of NMP. Malondialdehyde (MDA) levels were quantified as biochemical markers of iron overload and lipid peroxidation, respectively. Ferroptosis-related gene expression was assessed using molecular assays. Comparisons between male and female NDLs were used to determine the influence of sex on ferroptosis and oxidative injury during NMP. Results: NMP was successfully performed on NDLs (n = 5) from three male (56.3 ± 5.7 years) and two female donors (46.5 ± 0.7 years, p = 0.15). The fold-change in the oxidative stress marker MDA was comparable between female (1.2 ± 0.6) and male (1.0 ± 0.4) NDLs after 6 h NMP (p = 0.76). All livers showed upregulation of ferroptosis-related genes (Hypoxia-inducible factor 1 alpha, Iron Responsive Binding Elements 2, Ribosomal Protein L8, Ferritin Heavy Chain 1, Acyl-CoA synthetase family member 2, ATP synthase membrane subunit c locus 3, Heme-oxygenase 1, NAD(P)H Quinone Dehydrogenase 1, Tetratricopeptide Repeat Domain 35, Nuclear Factor Erythroid 2 Related Factor 2). ACSF2 expression was significantly higher in female NDLs compared with males undergoing 6 h NMP (3.6 ± 3.0 vs. 1.0 ± 0.7-fold change, p = 0.04). There were no sex-based significant differences observed in the expression of other ferroptosis-related genes (HIF-1α, IREB2, RPL8, FTH-1, ATP5G3, HO-1, NQO1, TTC35, and NRF2) between male and female NDLs. No gene reached statistical significance after false-discovery-rate (FDR) correction. Conclusions: Normothermic machine perfusion of NDLs was feasible, and no sex-related differences were observed in MDA levels or most ferroptosis-related gene expression after 6 h. Although ACSF2 showed higher expression in female livers, this was not significant after multiple testing correction, highlighting the need for larger studies to explore sex-dependent ferroptosis signaling during liver preservation.