Sleeve gastrectomy ameliorated high-fat diet (HFD)-induced non-alcoholic fatty liver disease and upregulated the nicotinamide adenine dinucleotide +/ Sirtuin-1 pathway in mice

Bariatric surgery post-liver transplantation: A Belgian nationwide study

Weight gain poses a rising concern post-liver transplantation (LT), and metabolic dysfunction-associated steatotic liver disease might impair graft health. The timing is crucial when considering bariatric surgery (BS) in a population with liver disease or transplantation. BS can be considered for post-LT weight gain, although the evidence is limited and the long-term outcome still uncertain. We conducted a national retrospective analysis in 5 Belgian transplant centers and included 25 patients with an LT followed by a bariatric procedure. A total of 187 LT patients without BS were included for comparison. Clinical, biochemical, and outcome data were retrospectively retrieved. In our nationwide cohort, 25 patients had undergone BS post-LT, at a median 3.5 years after LT. Twenty-one (84.0%) patients received a sleeve gastrectomy (SG). Patients were predominantly male (72.0%), with a lower age at time of transplantation compared with the non-BS population (54.5 vs. 60.6, p <0.001). Weight loss was significant and sustained, with a decrease in body mass index from 41.0±4.5 pre-BS to 32.6±5.8 1-3 years post-BS ( p <0.001) and 31.1±5.8 3-5 years post-BS ( p <0.001). Three pre-BS (12.0%) patients presented with recurrent and one (4.0%) de novo metabolic dysfunction-associated steatotic liver disease after LT, with 100% resolution post-BS ( p =0.016). Notable reductions were observed in alanine transaminase levels (40.5±28.5 U/L to 27.1±25.1 U/L post-BS, p =0.05) and HbA1c levels (6.9±1.6 to 6.0±1.4 post-BS, p <0.001). Three patients were re-transplanted, and eight patients died, of which five (20.0%) due to a nonhepatic malignancy and one (4.0%) due to liver failure. SG is the favored BS post-LT and has proven to be safe and feasible in a post-LT setting with favorable metabolic consequences. SG post-LT is a valid treatment for de novo and recurrent metabolic dysfunction-associated steatotic liver disease post-LT. Although we report on the largest cohort to date, there is still a need for larger cohorts to examine the effect of BS on patient and graft survival.

Key genes involved in nonalcoholic steatohepatitis improvement after bariatric surgery

Background

Nonalcoholic steatohepatitis (NASH) is the advanced stage of nonalcoholic fatty liver disease (NAFLD), one of the most prevalent chronic liver diseases. The effectiveness of bariatric surgery in treating NASH and preventing or even reversing liver fibrosis has been demonstrated in numerous clinical studies, but the underlying mechanisms and crucial variables remain unknown.

Methods

Using the GSE135251 dataset, we examined the gene expression levels of NASH and healthy livers. Then, the differentially expressed genes (DEGs) of patients with NASH, at baseline and one year after bariatric surgery, were identified in GSE83452. We overlapped the hub genes performed by protein-protein interaction (PPI) networks and DEGs with different expression trends in both datasets to obtain key genes. Genomic enrichment analysis (GSEA) and genomic variation analysis (GSVA) were performed to search for signaling pathways of key genes. Meanwhile, key molecules that regulate the key genes are found through the construction of the ceRNA network. NASH mice were induced by a high-fat diet (HFD) and underwent sleeve gastrectomy (SG). We then cross-linked the DEGs in clinical and animal samples using quantitative polymerase chain reaction (qPCR) and validated the key genes.

Results

Seven key genes (FASN, SCD, CD68, HMGCS1, SQLE, CXCL10, IGF1) with different expression trends in GSE135251 and GSE83452 were obtained with the top 30 hub genes selected by PPI. The expression of seven key genes in mice after SG was validated by qPCR. Combined with the qPCR results from NASH mice, the four genes FASN, SCD, HMGCS1, and CXCL10 are consistent with the biological analysis. The GSEA results showed that the 'cholesterol homeostasis' pathway was enriched in the FASN, SCD, HMGCS1, and SQLE high-expression groups. The high-expression groups of CD68 and CXCL10 were extremely enriched in inflammation-related pathways. The construction of the ceRNA network obtained microRNAs and ceRNAs that can regulate seven key genes expression.

Conclusion

In summary, this study contributes to our understanding of the mechanisms by which bariatric surgery improves NASH, and to the development of potential biomarkers for the treatment of NASH.

Alterations in gastric and gut microbiota following sleeve gastrectomy in high-fat diet-induced obese rats

Obesity is considered a high-risk disease and a global epidemic, and the number of obese patients is rising at an alarming rate worldwide. High-fat diet-induced dysbiosis of the intestinal microbiota is considered an essential factor related to obesity. Bariatric surgery induces a sharp decrease in fat content and effectively improves the metabolism of obese individuals. Herein, we aimed to investigate the effects of a high-fat diet-induced obesity and the alterations in gastric and intestinal microbiota resulting from sleeve gastrectomy on clinical outcomes. We performed 16S sequencing of gastric and fecal samples obtained from rats in three treatment groups: normal chow diet, high-fat diet (HFD), and sleeve gastrectomy after HDF for 14 weeks. The area under the curve of fasting glucose and the levels of leptin and low-density lipoproteins were significantly different between groups. Microbial taxa that were highly correlated with several clinical parameters were identified for each group. Glyoxylate and dicarboxylate, taurine and hypotaurine, butanoate, nitrogen, and pyrimidine metabolism and aminoacyl-transfer ribonucleic acid biosynthesis were affected by bariatric surgery and were significantly associated with changes in the composition of gastric and fecal microbiomes. Connectivity and co-occurrence were higher in fecal samples than in gastric tissues. Our results elucidated the positive effects of sleeve gastrectomy in obesity and shed light on changes in the microbiomes of gastric and fecal samples.

Patients hospitalized with alcohol-related liver disease and prior bariatric surgery are more prone to develop acute-on-chronic liver failure

BACKGROUND & AIMS

Patients with a history of bariatric surgery (BS) are susceptible to developing alcohol use disorder. We and others have previously shown that these patients can develop severe alcohol-related liver disease (ARLD). Our aim was to describe the demographics, co-morbidities and mortality of a hospitalized population diagnosed with alcohol-related liver disease, in relation to BS.

METHODS

We included 299 patients hospitalized with ARLD at the Ghent University Hospital between 1 January 2018 and 31 December 2022. Clinical, biochemical and outcome data were retrospectively retrieved from the most recent hospitalization. Statistical analysis was performed using the t test, Mann-Whitney U and χ2 tests.

RESULTS

Thirteen per cent (39/299) of patients admitted with ARLD had a history of bariatric surgery, of whom 25 (64.1%) had undergone Roux-en-Y gastric bypass. Patients with a history of BS were predominantly female (76.9%), in contrast to the non-BS population (29.2%) (p < .0001), and despite being significantly younger (p < .0001) and had a similar survival (61.5% vs. 58.1%). Bariatric surgery and older age at diagnosis were both significantly associated with poorer transplant-free survival. The cause of death was acute-on-chronic liver failure in 73.3% of BS patients, compared to only 19.2% of those without a history of BS (p < .0001). The weekly amount of alcohol consumed (p = .012) and duration of use (p < .0001) were significantly lower/shorter in the BS population.

CONCLUSIONS

BS patients hospitalized with ARLD are predominantly younger women with a lower cumulative alcohol consumption compared to those without prior BS. BS impacted transplant-free survival, with ACLF as the predominant cause of death in these patients.

Why Is Longevity Still a Scientific Mystery? Sirtuins-Past, Present and Future

The sirtuin system consists of seven highly conserved regulatory enzymes responsible for metabolism, antioxidant protection, and cell cycle regulation. The great interest in sirtuins is associated with the potential impact on life extension. This article summarizes the latest research on the activity of sirtuins and their role in the aging process. The effects of compounds that modulate the activity of sirtuins were discussed, and in numerous studies, their effectiveness was demonstrated. Attention was paid to the role of a caloric restriction and the risks associated with the influence of careless sirtuin modulation on the organism. It has been shown that low modulators' bioavailability/retention time is a crucial problem for optimal regulation of the studied pathways. Therefore, a detailed understanding of the modulator structure and potential reactivity with sirtuins in silico studies should precede in vitro and in vivo experiments. The latest achievements in nanobiotechnology make it possible to create promising molecules, but many of them remain in the sphere of plans and concepts. It seems that solving the mystery of longevity will have to wait for new scientific discoveries.

Duodenal-jejunal bypass increases intraduodenal bile acids and upregulates duodenal SIRT1 expression in high-fat diet and streptozotocin-induced diabetic rats

BACKGROUND

The mechanisms underlying diabetes remission after duodenal-jejunal bypass (DJB) remain elusive. In DJB surgery, the duodenum is excluded. However, the duodenum has emerged as an important regulator of glucose homeostasis, and elevated duodenal SIRT1 leads to improved hepatic insulin sensitivity. After DJB, bile acids (BAs) in the duodenum are not mixed and diluted by the ingested food. And activation of BA receptors promotes SIRT1 expression in many tissues. We hypothesized that BA-mediated upregulation of SIRT1 may contribute to diabetic control after DJB.

AIM

To investigate the surgical effects of DJB on duodenal SIRT1 expression and uncover the potential crosslinks between BAs and SIRT1.

METHODS

Twenty diabetic rats were randomly allocated to the sham (n = 10) and DJB (n = 10) groups. Body weight, food intake, fasting blood glucose (FBG), serum and intraduodenal total BA (TBA) levels were measured accordingly. Oral glucose tolerance test (OGTT) and intraperitoneal pyruvate tolerance test (ipPTT) were performed to evaluate the effects of surgeries on systemic glucose disposal and hepatic gluconeogenesis. The key genes of BA signaling pathway in the duodenal mucosa, including farnesoid X receptor (FXR), small heterodimer partner (SHP), and Takeda G-protein-coupled receptor 5 (TGR5) were evaluated by real-time quantitative polymerase chain reaction 8 wk postoperatively. The duodenal SIRT1, AMPK, and phosphorylated AMPK (p-AMPK) levels were evaluated by western blotting. Rat small intestine epithelial IEC-6 cells were treated with GW4064 and INT-777 to verify the effects of BAs on SIRT1 expression in enterocytes.

RESULTS

The DJB group exhibited body weight and food intake comparable to those of the sham group at all postoperative time points. The FBG level and area under the curve for the OGTT and ipPTT were significantly lower in the DJB group. The DJB group exhibited higher fasting and postprandial serum TBA levels than the sham group at both 2 and 8 wk postoperatively. At 8 wk after surgery, the DJB group showed higher intraluminal TBA concentration, upregulated mRNA expression of FXR and SHP, and elevated protein expression of SIRT1 and p-AMPK in the descending and horizontal segments of the duodenum. Activation of FXR and TGR5 receptors by GW4064 and INT-777 increased the mRNA and protein expression of SIRT1 and promoted the phosphorylation of AMPK in IEC-6 cells.

CONCLUSION

DJB elevates intraduodenal BA levels and activates the duodenal BA signaling pathway, which may upregulate duodenal SIRT1 and further contribute to improved glucose homeostasis after DJB.

NAD+ and NAFLD - caution, causality and careful optimism

The prevalence of non-alcoholic fatty liver disease (NAFLD) is increasing worldwide, and new treatments are sorely needed. Nicotinamide adenine dinucleotide (NAD⁺ ) has been proposed as a potential target to prevent and reverse NAFLD. NAD⁺ is an important redox factor for energy metabolism and is used as a substrate by a range of enzymes, including sirtuins (SIRT), which regulates histone acetylation, transcription factor activity and mitochondrial function. NAD⁺ is also a precursor for reduced nicotinamide adenine dinucleotide phosphate (NADPH), which is an important component of the antioxidant defense system. NAD⁺ precursors such as nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) are available as over-the-counter dietary supplements, and oral supplementation with these precursors increases hepatic NAD⁺ levels and prevents hepatic lipid accumulation in pre-clinical models of NAFLD. NAD⁺ precursors have also been found to improve hepatic mitochondrial function and decrease oxidative stress in pre-clinical NAFLD models. NAD⁺ repletion also prevents NAFLD progression to non-alcoholic steatohepatitis (NASH), as NAD⁺ precursor supplementation is associated with decreased hepatic stellate cell activation, and decreased fibrosis. However, initial clinical trials have only shown modest effects when NAD⁺ precursors were administrated to people with obesity. We review the available pre-clinical investigations of NAD⁺ supplementation for targeting NAFLD, and discuss how data from the first clinical trials can be reconciled with observations from preclinical research.