Background and Aims: The disease progression of nonalcoholic fatty liver disease (NAFLD) from simple steatosis (NAFL) to nonalcoholic steatohepatitis (NASH) is driven by multiple factors. Berberine (BBR) is an ancient Chinese medicine and has various beneficial effects on metabolic diseases, including NAFLD/NASH. However, the underlying mechanisms remain incompletely understood due to the limitation of the NASH animal models used. Methods: A high-fat and high-fructose diet-induced mouse model of NAFLD, the best available preclinical NASH mouse model, was used. RNAseq, histological, and metabolic pathway analyses were used to identify the potential signaling pathways modulated by BBR. LC–MS was used to measure bile acid levels in the serum and liver. The real-time RT-PCR and Western blot analysis were used to validate the RNAseq data. Results: BBR not only significantly reduced hepatic lipid accumulation by modulating fatty acid synthesis and metabolism but also restored the bile acid homeostasis by targeting multiple pathways. In addition, BBR markedly inhibited inflammation by reducing immune cell infiltration and inhibition of neutrophil activation and inflammatory gene expression. Furthermore, BBR was able to inhibit hepatic fibrosis by modulating the expression of multiple genes involved in hepatic stellate cell activation and cholangiocyte proliferation. Consistent with our previous findings, BBR’s beneficial effects are linked with the downregulation of microRNA34a and long noncoding RNA H19, which are two important players in promoting NASH progression and liver fibrosis. Conclusion: BBR is a promising therapeutic agent for NASH by targeting multiple pathways. These results provide a strong foundation for a future clinical investigation.

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.

Short bowel syndrome (SBS) is a major cause of intestinal failure (IF) that may require long-term parenteral nutrition (PN) support. However, long-term PN is accompanied by severe complications such as catheter-related blood stream infection (CRBSI) and intestinal failure-associated liver disease (IFALD), and it is associated with high healthcare costs. In this study, we characterized the plasma metabolomic profile and investigated the role of metabolism in predicting long-term PN in pediatric patients with SBS. Untargeted metabolomics was performed in plasma samples from 20 SBS patients with PN support: 6 patients had IFALD and 14 patients had no liver disease. As controls, 18 subjects without liver or intestinal diseases were included for the analysis. SBS patients had distinct plasma metabolomic signatures compared to controls, and several pathways associated with amino acid metabolism and cell death were significantly changed. The presence of IFALD in SBS was associated with alterations of metabolites mainly classified as “amino acids, peptides, and analogues” and “benzene and derivatives”. Serum direct bilirubin levels were negatively correlated with levels of uridine, skatole, and glabrol. Importantly, SBS patients with long-term PN showed significantly increased levels of glutamine compared to those in the short-term PN group. Finally, using multivariate logistic regression analysis, we developed a prediction model including glutamine and creatinine to identify pediatric SBS patients who need long-term PN support. These findings underscore the potential key role of the metabolome in SBS with IF and suggest that metabolomic profiles could be used in long-term PN assessment.

Enterocyte apoptosis induced by lipid emulsions is a key cause of intestinal atrophy under total parenteral nutrition (TPN) support, and our previous work demonstrated that olive oil lipid emulsion (OOLE) could induce enterocyte apoptosis via CUGBP, Elav‐like family member 1 (CELF1)/ apoptosis‐inducing factor (AIF) pathway. As TPN‐associated complications are partially related to choline deficiency, we aimed to address whether choline supplementation could attenuate OOLE‐induced enterocyte apoptosis. Herein we present evidence that supplementary choline exhibits protective effect against OOLE‐induced enterocyte apoptosis both in vivo and in vitro. In a rat model of TPN, substantial reduction in apoptotic rate along with decreased expression of CELF1 was observed when supplementary choline was added to OOLE. In cultured Caco‐2 cells, supplementary choline attenuated OOLE‐induced apoptosis and mitochondria dysfunction by suppressing CELF1/AIF pathway. Compared to OOLE alone, the expression of CELF1 and AIF was significantly decreased by supplementary choline, whereas the expression of Bcl‐2 was evidently increased. No obvious alterations were observed in Bax expression and caspase‐3 activation. Mechanistically, supplementary choline repressed the expression of CELF1 by increasing the recruitment of CELF1 mRNA to processing bodies, thus resulting in suppression of its protein translation. Taken together, our data suggest that supplementary choline exhibits effective protection against OOLE‐induced enterocyte apoptosis, and thus, it has the potential to be used for the prevention and treatment of TPN‐induced intestinal atrophy.

Disassembly of tight junctions is a major cause of intestinal barrier dysfunction under total parenteral nutrition (TPN), but the precise mechanisms have not been fully understood. Normally, RNA binding protein Lin 28A is highly restricted to embryonic stem cells and dramatically decreases as differentiation progresses; however, in our preliminary study it was found aberrantly increased in the intestinal epithelial cells of TPN rats, and thus its mechanism of action needs to be addressed. Herein, we report a pivotal role of Lin 28A in the regulation of tight junctions, which induces a sustained translational repression of Occludin, leading to disruption of intestinal barrier function under TPN. Using a rat model of TPN, we found time‐dependent upregulation of Lin 28A, negatively correlated with Occludin. Using mouse intestinal organoids and human gut‐derived Caco‐2 cells as in vitro models, we found that expression of Occludin could be significantly suppressed by ectopic overexpression of Lin 28A. The underlying mechanisms may be partially attributed to translational repression, as the abundance of Occludin transcripts in polysomes was dramatically reduced by Lin 28A (polysomal profiling). Furthermore, Lin 28A was found to directly bind to Occludin mRNA 3′ untranslated coding region (UTR), thereby repressing the translation of Occludin transcripts through decapping enzyme 1A (DCP1a). Taken together, our findings revealed that Lin 28A/Occludin axis may be a novel mechanism accounting for the development of barrier dysfunction under TPN.

Intestinal barrier dysfunction is a major complication of total parenteral nutrition (TPN). Our preliminary study revealed that intestinal P‐glycoprotein (P‐gp) was significantly downregulated under TPN treatment followed by disruption of barrier function, and thus the significance of early downregulation of P‐gp needs to be addressed. Herein, we report a pivotal role of P‐gp in the development of intestinal barrier dysfunction under TPN. Functional suppression of P‐gp may facilitate bacterial attachment to intestinal epithelial cells (IECs) and thereby induce degradation of tight junctions to trigger barrier dysfunction. By using a rat model of TPN, we found early downregulation of P‐gp function in ileum after 3‐day TPN, followed by disruption of barrier function after 7‐day TPN. By using Escherichia coli ( E. coli ) k88 and DH5α as type strains, we found significantly increased bacterial attachment to IECs in TPN group compared to sham. By using Caco‐2 cells as an IEC model in vitro, we found that functional suppression of P‐gp remarkably facilitated bacterial attachment to Caco‐2 cells, leading to subsequent disruption of intestinal barrier function. Of note, Occludin was significantly downregulated by bacterial attachment when P‐gp was functionally suppressed. Mechanistically, changes on Occludin were attributed to enhanced protein degradation instead of suppressed protein translation. Despite the half‐life of Occludin protein being unchanged by DH5α treatment alone, it was decreased by about 40% when P‐gp was simultaneously suppressed. Taken together, our findings revealed that early downregulation of intestinal P‐gp under TPN may be a potential therapeutic target to prevent the development of barrier dysfunction.