Parenteral nutrition (PN), a vital therapy for patients with intestinal failure, can lead to the development of parenteral nutrition-associated liver disease (PNALD). In this study, we aimed to investigate the role of Lactobacillus johnsonii (L. johnsonii) in a rat model of PNALD. Total parenteral nutrition (TPN)-fed rats were used to assess the role of L. johnsonii in liver steatosis, bile acid metabolism, gut microbiota, and hepatocyte apoptosis. We observed a depletion of L. johnsonii that was negatively correlated with the accumulation of glycochenodeoxycholic acid (GCDCA), a known apoptosis inducer, in rats subjected to TPN. L. johnsonii attenuated TPN-induced liver steatosis by inhibiting fatty acid synthesis and promoting fatty acid oxidation. TPN resulted in a decrease in bile acid synthesis and biliary bile secretion, which were partially restored by L. johnsonii treatment. The gut microbial profile revealed depletion of pathogenic bacteria in L. johnsonii-treated rats. L. johnsonii treatment reduced both hepatic GCDCA levels and hepatocyte apoptosis compared with the TPN group. In vitro, L. johnsonii treatment inhibited GCDCA-induced hepatocyte apoptosis via its bile salt hydrolase (BSH) activity. Our findings suggest that L. johnsonii protects against liver steatosis, bile acid dysregulation, and hepatocyte apoptosis in TPN-fed rats.

Pediatric intestinal failure (IF) is the reduction in gut function to below the minimum necessary for the absorption of macronutrients and/or water and electrolytes, such that intravenous supplementation is required to maintain health and/or growth. The overall goal in treating IF is to achieve intestinal adaptation; however, the underlying mechanisms have not been fully understood. In this study, by performing single-cell RNA sequencing in pediatric IF patients, we found that decreased Kruppel-Like Factor 4 (KLF4) may serve as the hub gene responsible for the functional deficit in mature enterocytes in IF patients, leading to the downregulation of solute carrier (SLC) family transporters (e.g., SLC7A9) and, consequently, nutrient malabsorption. We also found that inducible KLF4 was highly sensitive to the loss of certain enteral nutrients: in a rodent model of total parenteral nutrition mimicking the deprivation of enteral nutrition, the expression of KLF4 dramatically decreased only at the tip of the villus and not at the bottom of crypts. By using IF patient-derived intestinal organoids and Caco-2 cells as in vitro models, we demonstrated that the supplementation of decanoic acid (DA) could significantly induce the expression of KLF4 along with SLC6A4 and SLC7A9, suggesting that DA may function as a potential therapeutic strategy to promote cell maturation and functional improvement. In summary, this study provides new insights into the mechanism of intestinal adaptation depending on KLF4, and proposed potential strategies for nutritional management using DA.

Total parenteral nutrition (TPN) is life-saving therapy for the pediatric patients with intestinal failure (IF) who cannot tolerate enteral nutrition (EN). However, TPN-induced metabolic alterations are also a critical issue for the maintenance of intestinal homeostasis, and thus the global metabolomic signatures need to be addressed. In this study, ileal mucosal biopsies were collected from 12 neonatal Bama piglets receiving either EN or TPN for 14 days, and changes in the intestinal metabolism were examined by multi-omics (HM350 Metabolomics + Tandem Mass Tag (TMT)-based proteomics). As a result, a total of 240 compounds were identified by metabolomics, including 56 down-regulated and 9 up-regulated metabolites. Notably, tissue levels of fatty acyl-carnitines (decreased by 35–85%) and succinate (decreased by 89%) dramatically decreased in the TPN group, suggestive of disrupted processes of fatty acid oxidation (FAO) and the citrate cycle, respectively. Interestingly, however, no differences were found in the production of adenosine 5′-triphosphate (ATP) between groups, suggesting that these dysregulated metabolites may have mainly led to the loss of bioactive compounds rather than energy deficit. Additionally, 4813 proteins were identified by proteomics in total, including 179 down-regulated and 329 up-regulated proteins. The analysis of protein–protein interactions (PPI) indicated that most of the differentially expressed proteins were clustered into “lipid metabolism” and “innate immune responses”. In summary, this work provided new findings in TPN-induced intestinal metabolic alterations, which would be useful to the improvement of nutritional management for IF patients.