The impact of bariatric surgery on nonalcoholic steatohepatitis

Sleeve-gastrectomy results in improved metabolism and a massive stress response of the liver proteome in a mouse model of metabolic dysfunction-associated steatohepatitis

Background

Bariatric surgery has been shown to improve the histopathological findings in patients with obesity and metabolic dysfunction-associated steatohepatitis, but there are also reports about non-responders or progressive disease after bariatric interventions. Therefore, it is of utmost importance to understand the pathophysiological processes in the liver after bariatric surgery.

Materials and methods

In the present study, 4 weeks old male C57/Bl6 mice were fed a Western Diet to induce metabolic dysfunction-associated steatohepatitis and sleeve-gastrectomy (SG), or sham operation in the pair-fed and ad libitum control group were performed. Mice were observed for two or eight weeks after surgery and metabolic assessment was performed throughout the experiment. Histopathology, flow cytometry and proteomic analyses were conducted to evaluate hepatic inflammation, liver metabolism and affected signaling pathways.

Results

Weight loss was higher, and metabolism significantly improved after SG. Two weeks after SG major inflammatory and regulatory disturbances in the liver were observed. The proportion of hepatic CD3+NK1.1+ cells were decreased, and proteins involved in apoptosis like Fas, Casp1 and Casp9 or in the acute phase response were upregulated in SG mice. These disturbances decreased in the long-term and we observed an increase of many proteins involved in lipid metabolism eight weeks following SG.

Conclusions

The rapid weight loss and decrease of hepatic fat after SG lead to a proinflammatory response in the liver in the early phase after surgery, which changes to a more moderate immune response in the long-term. We suggest a preoperative risk stratification and postoperative surveillance depending on the histopathological findings.

The Effect of Non-Alcoholic Fatty Liver Disease on Weight Loss and Resolution of Obesity-Related Disorders After Bariatric Surgery

BACKGROUND

Patients undergoing bariatric surgery have a high incidence of non-alcoholic fatty liver disease (NAFLD). However, the effect of NAFLD or non-alcoholic steatohepatitis (NASH) on the weight loss and resolution of obesity-related disorders is a matter of debate.

METHODS

In this study, we compare the long-term outcomes after bariatric with the presence of NAFLD in the liver biopsy at the time of surgery.

RESULTS

The follow-up was available for 226 out of 288 patients. The mean follow-up time was 24.9 (± 13.6) months. The baseline histology showed that 112 patients (38.9%) had no NASH, 70 (24.3%) were borderline, and 106 (36.8%) had NASH. At follow-up, the mean BMI dropped from (52 ± 10.2) to (36.6 ± 8) kg/m 2. Excess weight loss (EWL) was similar in all NAFLD groups. Type 2 diabetes mellitus dropped from 35.7 to 11.4%, hypertension from 65.6 to 36.7%, hyperlipidemia from 62.3 to 33%, and obstructive sleep apnea from 37.5 to 14.9%. Only hyperlipidemia was significantly associated with NASH compared to the groups with no NASH or borderline NASH (p value = 0.002 and p value = 0.04, respectively) during the first two years of follow-up.

CONCLUSION

The beneficial effects of bariatric surgery are evident across all patients with NAFLD. Patients with NASH have comparable outcomes regarding weight loss and resolution of obesity-related comorbidities.

Glucose metabolism after bariatric surgery: implications for T2DM remission and hypoglycaemia

Although promising therapeutics are in the pipeline, bariatric surgery (also known as metabolic surgery) remains our most effective strategy for the treatment of obesity and type 2 diabetes mellitus (T2DM). Of the many available options, Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) are currently the most widely used procedures. RYGB and VSG have very different anatomical restructuring but both surgeries are effective, to varying degrees, at inducing weight loss and T2DM remission. Both weight loss-dependent and weight loss-independent alterations in multiple tissues (such as the intestine, liver, pancreas, adipose tissue and skeletal muscle) yield net improvements in insulin resistance, insulin secretion and insulin-independent glucose metabolism. In a subset of patients, post-bariatric hypoglycaemia can develop months to years after surgery, potentially reflecting the extreme effects of potent glucose reduction after surgery. This Review addresses the effects of bariatric surgery on glucose regulation and the potential mechanisms responsible for both the resolution of T2DM and the induction of hypoglycaemia.

Dysregulation of Components of the Inflammasome Machinery After Bariatric Surgery: Novel Targets for a Chronic Disease

BACKGROUND

Obesity is a metabolic chronic disease with important associated morbidities and mortality. Bariatric surgery is the most effective treatment for maintaining long-term weight loss in severe obesity and, consequently, for decreasing obesity-related complications, including chronic inflammation.

AIM

To explore changes in components of the inflammasome machinery after bariatric surgery and their relation with clinical/biochemical parameters at baseline and 6 months after bariatric surgery.

PATIENTS AND METHODS

Twenty-two patients with morbid-obesity that underwent bariatric surgery (sleeve gastrectomy and Roux-en-Y gastric bypass) were included. Epidemiological/clinical/anthropometric/biochemical evaluation was performed at baseline and 6 months after bariatric surgery. Inflammasome components and inflammatory-associated factors [nucleotide-binding oligomerization domain-like receptors (NLRs), inflammasome activation components, cytokines and inflammation/apoptosis-related components, and cell-cycle and DNA-damage regulators) were evaluated in peripheral blood mononuclear cells (PBMCs) at baseline and 6 months after bariatric surgery. Clinical molecular correlations/associations were analyzed. Functional parameters (lipid accumulation/viability/apoptosis) were analyzed in response to specific inflammasome components silencing in liver HepG2 cells).

RESULTS

A profound dysregulation of inflammasome components after bariatric surgery was found, especially in NLRs and cell-cycle and DNA damage regulators. Several components were associated with baseline metabolic comorbidities including type 2 diabetes (C-C motif chemokine ligand 2/C-X-C motif chemokine receptor 1/sirtuin 1), hypertension (absent in melanoma 2/ASC/purinergic receptor P2X 7), and dyslipidemia [C-X-C motif chemokine ligand 3 (CXCL3)/NLR family pyrin domain containing (NLRP) 7) and displayed changes in their molecular profile 6 months after bariatric surgery. The gene expression fingerprint of certain factors NLR family CARD domain containing 4 (NLRC4)/NLRP12/CXCL3)/C-C motif chemokine ligand 8/toll-like receptor 4) accurately differentiated pre- and postoperative PBMCs. Most changes were independent of the performed surgical technique. Silencing of NLRC4/NLRP12 resulted in altered lipid accumulation, apoptosis rate, and cell viability in HepG2 cells.

CONCLUSION

Bariatric surgery induces a profound alteration in the gene expression pattern of components of the inflammasome machinery in PBMCs. Expression and changes of certain inflammasome components are associated to baseline metabolic comorbidities, including type 2 diabetes, and may be related to the improvement and reversion of some obesity-related comorbidities after bariatric surgery.

Gastric Bypass Increases Circulating Bile Acids and Activates Hepatic Farnesoid X Receptor (FXR) but Requires Intact Peroxisome Proliferator Activator Receptor Alpha (PPARα) Signaling to Significantly Reduce Liver Fat Content

BACKGROUND

We interrogate effects of gastric bypass (RYGB), compared with a low-calorie diet, on bile acid (BA), liver fat, and FXR, PPARα, and targets in rats with obesity and non-alcoholic fatty liver disease (NAFLD).

METHODS

Male Wistar rats received a high-fat diet (obese/NAFLD, n=24) or standard chow (lean, n=8) for 12 weeks. Obese/NAFLD rats had RYGB (n=11), sham operation pair-fed to RYGB (pair-fed sham, n=8), or sham operation (sham, n=5). Lean rats had sham operation (lean sham, n=8). Post-operatively, five RYGB rats received PPARα antagonist GW6417. Sacrifice occurred at 7 weeks. We measured weight changes, fasting total plasma BA, and liver % steatosis, triglycerides, and mRNA expression of the nuclear receptors FXR, PPARα, and their targets SHP and CPT-I.

RESULTS

At sacrifice, obese sham was heavier (p<0.01) than all other groups that had lost similar weight loss. Obese sham had lower BA levels and lower hepatic FXR, SHP, and CPT-I mRNA expression than lean sham (P<0.05, for all comparisons). RYGB had increased BA levels compared with obese and pair-fed sham (P<0.05, for both), while pair-fed sham had BA levels, similar to obese sham. Compared with pair-fed sham, RYGB animals had increased liver FXR and PPARα expression and signaling (P<0.05). Percentage of steatosis was lower in RYGB and lean sham, relative to obese and pair-fed sham (P<0.05, for all comparisons). PPARα inhibition after RYGB resulted in similar weight loss but higher liver triglyceride content (P=0.01) compared with RYGB alone.

CONCLUSIONS

RYGB led to greater liver fat loss than low-calorie diet, an effect associated to increased fasting BA levels and increased expression of modulators of liver fat oxidation, FXR, and PPARα. However, intact PPARα signaling was necessary for resolution of NAFLD after RYGB.

Metabolic surgery: A clinical update

Metabolic and bariatric surgery has grown beyond 'experimental' weight-loss surgery. As techniques have advanced over the last few decades, so has the growing body of research and evidence, proving that both weight-loss and metabolic health improvement are induced. Metabolic surgery has become the more appropriate term for weight-loss surgery because of the altered gastrointestinal anatomy and subsequent beneficial metabolic effects. Although the tool of metabolic surgery has been well refined, a large portion of the global population does not have adequate access to it. This clinical update aims to (a) inform healthcare providers from all disciplines about the myriad of benefits of metabolic surgery and (b) equip them with the necessary knowledge to bridge the gap between patients in need of metabolic treatment and the therapies in metabolic surgery available to them.

The impact of bariatric surgery on nonalcoholic fatty liver disease as measured using non-invasive tests

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is common in bariatric surgery candidates. We evaluated the effect of sleeve gastrectomy (SG) on NAFLD using validated non-invasive measures.

METHODS

Patients with morbid obesity and NAFLD, planned for SG, were evaluated before and after surgery. Data collected included anthropometrics, biochemistry, adiponectin, SteatoTest™, NashTest™, FibroTest™, OWLiver® test and real-time ShearWave™ elastography (SWE).

RESULTS

Twenty-six subjects were included in the study, mean age 44.1 ± 4.8 years, 69.2% males. One year following SG, body mass index decreased significantly from 41.7 ± 4.8 kg/m² to 29.6 ± 4.5 kg/m². Concomitantly, significant improvements in triglycerides, ALT, diabetes markers and adiponectin were observed. Mean steatosis, as measured by SteatoTest™, was significantly improved. Steatohepatitis score measured by NashTest™ and OWLiver® significantly decreased. Mean fibrosis, as measured by SWE liver stiffness and FibroTest™, did not change over time.

CONCLUSION

Steatosis and steatohepatitis are significantly improved by SG as measured by non-invasive measures.

Established and emerging factors affecting the progression of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease affecting approximately 25% of the global population. Although a majority of NAFLD patients will never experience liver-related symptoms it is estimated that 5-10% will develop cirrhosis-related complications with risk of death or need for liver transplantation. NAFLD is closely associated with cardiovascular disease and components of the metabolic syndrome. However, NAFLD is not uncommon in lean individuals and may in these subjects represent a different entity with separate pathophysiological mechanisms involved implying a higher risk for development of end-stage liver disease. There is considerable fluctuation in the histopathological course of NAFLD that may partly be attributed to lifestyle factors and dietary composition. Nutrients such as fructose, monounsaturated fatty acids, and trans-fatty acids may aggravate NAFLD. Presence of type 2 diabetes mellitus seems to be the most important clinical predictor of liver-related morbidity and mortality in NAFLD. Apart from severity of the metabolic syndrome, genetic polymorphisms and environmental factors, such as moderate alcohol consumption, may explain the variation in histopathological and clinical outcome among NAFLD patients.

Applicability and Results of Liver Stiffness Measurement and Controlled Attenuation Parameter Using XL Probe for Metabolic-Associated Fatty Liver Disease in Candidates to Bariatric Surgery. A Single-Center Observational Study

PURPOSE

Patients with morbid obesity are at high risk of liver fibrosis due to metabolic-associated fatty liver disease. Data on liver stiffness measurement (LSM) and controlled attenuation parameter (CAP) by vibration-controlled transient elastography (VCTE, FibroScan®) XL probe for liver fibrosis and steatosis assessment in morbid obesity are needed.

MATERIALS AND METHODS

LSM and CAP were measured in candidates to bariatric surgery at a single center during 12 months. In patients who underwent an intraoperative liver biopsy, we compared LSM and CAP with histology findings. Comorbidities, body mass index, type of surgery, and infections after surgery were collected and analyzed.

RESULTS

Of the eighty-three patients assessed by XL probe, 49 (59%; female in 63%, BMI 42.6 ± 5.1 kg/m²) had a valid LSM and CAP measurement. LSM was 7.0 ± 3.9 kPa and CAP 329 ± 57 dB/m. In the 14 patients undergoing intraoperative liver biopsy, all had steatosis (severe in 50%), 6 (43%) had NASH (NAS ≥ 5), and 4 (29%) showed significant or bridging fibrosis. LSM accurately discriminated between patients with and without significant or severe fibrosis (AUROC 0.833) and CAP well-identified patients with or without ≥S2 steatosis (AUROC 0.896). Nine of 49 patients (18%) tested positive for significant/severe fibrosis by LSM (cut-off 8.9 kPa).

CONCLUSION

Applicability of LSM and CAP by XL probe in patients candidate to bariatric surgery was moderate. However, when technically successful, their reliability to diagnose severe steatosis and fibrosis related to MAFLD was good.

Safety and Efficacy of Bariatric Surgery in Advanced Liver Fibrosis

BACKGROUND

There is limited data on the safety and efficacy of metabolic and bariatric (MBS) surgery in patients with advanced liver fibrosis.

METHODS

This is a retrospective analysis of data of patients with advanced liver fibrosis undergoing MBS at a tertiary care centre. Weight loss and complications were analysed. Transient elastography and liver biopsy findings 1 year after surgery were compared with baseline.

RESULTS

Twenty-two patients had cirrhosis and 16 had stage 3 fibrosis; all were Child Pugh A. Majority (76%) underwent sleeve gastrectomy. Mean excess BMI loss was 65.8 ± 18.9%. There were no leaks or 30-day mortality. One patient with cirrhosis had late mortality due to liver decompensation. Preoperative and postoperative median LSM were 15.5 kPa (interquartile range IQR = 24.4-11.6) and 10.9 kPa (IQR 19.3-7.6), respectively. Preoperative and postoperative median CAP were 352.5 dB/m (IQR = 372-315.5) and 303 dB/m (IQR 331-269.5), respectively. On follow-up biopsy, nine of twelve patients had improvement in fibrosis, while three had no change. Four out of five patients in the cirrhotic cohort had improvement in fibrosis stage and LSM improved in all of them. Five out of seven patients with stage 3 fibrosis had an improvement in fibrosis stage and none progressed to cirrhosis. LSM improved in three of these five patients.

CONCLUSION

MBS has the potential to ameliorate advanced liver fibrosis, including cirrhosis. Transient elastography can be used as an effective tool for screening and follow-up of liver disease in patients undergoing MBS.

The Effect of Laparoscopic Sleeve Gastrectomy on Nonalcoholic Fatty Liver Disease

Obesity is associated with nonalcoholic fatty liver disease which is one of the most common causes of chronic liver disease. FibroScan is a noninvasive tool for liver stiffness measurement and controlled attenuation parameter to evaluate liver steatosis and fibrosis. We aimed to demonstrate the effect of laparoscopic sleeve gastrectomy on liver steatosis and fibrosis. Of the 120 consecutive patients screened, 72 were enrolled in this study. FibroScan M probe and XL probe were used for the evaluation of liver steatosis and fibrosis. Fifty-two patients (72.2%) were female individuals and 20 (27.8%) were male individuals; the mean age was 37.9±10.4 years. Percentage of excess weight loss was significant at the third and sixth months: 57.2±18.3 (P<0.05) and 81.4±24.6 (P<0.05), respectively. Mean preoperative controlled attenuation parameter and liver stiffness measurement values were 309.2±68.7 dB/m and 7.5±5.0 kPa, respectively, and significantly declined to 217.4±56.4 dB/m and 5.6±2.5 kPa, respectively, at sixth postoperative month (P<0.001 and <0.01, respectively). These results suggest that laparoscopic sleeve gastrectomy is associated with significant improvement in liver steatosis and fibrosis. Bariatric surgery has a beneficial effect on nonalcoholic fatty liver disease in morbidly obese patients.

Whole-grain consumption and its effects on hepatic steatosis and liver enzymes in patients with non-alcoholic fatty liver disease: a randomised controlled clinical trial

Non-alcoholic fatty liver disease (NAFLD) is a considerable challenge to public health across the globe. Whole grain is highly recommended as an inseparable part of a healthy diet and has been proposed as an effective way to manage NAFLD. The objective in the present study was to evaluate the effects of whole-grain consumption on hepatic steatosis and liver enzymes as primary outcomes in patients with NAFLD. Over the 12 weeks of this open-label, randomised controlled clinical trial, 112 patients (mean age 43 (sd 8·7) years; BMI 32·2 (sd 4·3) kg/m2) were randomly assigned to two groups to receive dietary advice, either to obtain at least half of their cereal servings each day from whole-grain foods or from usual cereals. By the end of the study, the grades of NAFLD showed a significant decrease in the intervention group (P < 0·001). In addition, a significant reduction in serum concentration of alanine aminotransferase (P < 0·001), aspartate aminotransferase (P < 0·001), γ-glutamyltransferase (P = 0·009), systolic blood pressure (P = 0·004) and diastolic blood pressure (P = 0·008) was observed in the intervention group compared with the control group. After adjusting, however, no significant differences were found between the two groups in terms of lipid profile, glycaemic status and anthropometric measurements. Overall, our study demonstrated that consumption of whole grains for 12 weeks had beneficial effects on hepatic steatosis and liver enzymes concentrations in patients with NAFLD.

Bariatric surgery is associated with reduction in non-alcoholic steatohepatitis and hepatocellular carcinoma: A propensity matched analysis

INTRODUCTION

Obesity is a risk factor for non-alcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC). Bariatric surgery can provide durable weight-loss, but little is known about the later development of NASH and HCC after surgery.

METHODS

Bariatric surgery (n = 3,410) and obese controls (n = 46,873) from an institutional data repository were propensity score matched 1:1 by demographics, comorbidities, BMI, and socioeconomic factors. Comparisons were made through paired univariate analysis and conditional logistic regression.

RESULTS

Total of 4,112 patients were well matched with no significant baseline differences except initial BMI (49.0 vs 48.2, p = 0.04). Bariatric group demonstrated fewer new-onset NASH (6 0.0% vs 10.3%, p < 0.0001) and HCC (0.05% vs 0.34%, p = 0.03) over a median follow-up of 7.1 years. After risk-adjustment, bariatric surgery was independently associated with reduced development of NASH (OR 0.52, p < 0.0001).

CONCLUSIONS

Bariatric surgery is associated with reduced incidence of NASH and HCC in this large propensity matched cohort. This further supports the use of bariatric surgery for morbidly obese patients to ameliorate NASH cirrhosis and development of HCC.

Concomitant PPARα and FXR Activation as a Putative Mechanism of NASH Improvement after Gastric Bypass Surgery: a GEO Datasets Analysis

BACKGROUND

Compared to non-surgical weight loss (Diet), weight loss after Roux-en-Y gastric bypass (RYGB) results in greater rates of non-alcoholic steatohepatitis (NASH) resolution. Changes in bile acid physiology and farnesoid X receptor (FXR) signaling are suspected mediators of postoperative NASH improvement. Recent experimental evidence suggests that upregulation of hepatic peroxisome proliferator-activated receptor α (PPARα) activity might also impact NASH improvement. As FXR partly regulates PPARα, we compared resolution of NASH and changes in hepatic PPARα and FXR gene expression following Diet and RYGB.

METHODS

We searched the Gene Expression Omnibus database to identify human studies with liver biopsies containing genomic data and histologic NASH features, at baseline and after Diet or RYGB. Microarray data were extracted for PPARα and FXR gene expression analyses using GEOquery R package v.2.42.0.

RESULTS

We identified one study (GSE83452) where patients underwent either Diet (n = 29) or RYGB (n = 25). NASH prevalence was similar at baseline (Diet 76% versus RYGB 60%, P = ns). After 1 year, NASH resolved in 93.3% of RYGB but only in 27.3% of Diet (P < 0.001). Hepatic PPARα and FXR gene expression increased only after RYGB (P < 0.001). These changes were also found when analyzing only patients that resolved NASH (P < 0.01), and patients without NASH at baseline and follow-up (P < 0.05).

CONCLUSIONS

Compared to Diet, RYGB results in greater NASH resolution with concurrent upregulation of hepatic PPARα and FXR. Our findings point to concurrent PPARα and FXR activation, triggered by RYGB, as a potential mechanism to improve NASH.

Nonalcoholic fatty liver disease and gastric bypass surgery regulate serum and hepatic levels of pyruvate kinase isoenzyme M2

Treatment of nonalcoholic fatty liver disease (NAFLD) focuses on the underlying metabolic syndrome, and Roux-en-Y gastric bypass surgery (RYGB) remains one of the most effective options. In rodents and human patients, RYGB induces an increase in the gene and protein expression levels of the M2 isoenzyme of pyruvate kinase (PKM2) in the jejunum. Since PKM2 can be secreted in the circulation, our hypothesis was that the circulating levels of PKM2 increase after RYGB. Our data, however, revealed an unexpected finding and a potential new role of PKM2 for the natural history of metabolic syndrome and NAFLD. Contrary to our initial hypothesis, RYGB-treated patients had decreased PKM2 blood levels compared with a well-matched group of patients with severe obesity before RYGB. Interestingly, PKM2 serum concentration correlated with body mass index before but not after the surgery. This prompted us to evaluate other potential mechanisms and sites of PKM2 regulation by the metabolic syndrome and RYGB. We found that in patients with NAFLD and nonalcoholic steatohepatitis (NASH), the liver had increased PKM2 expression levels, and the enzyme appears to be specifically localized in Kupffer cells. The study of murine models of metabolic syndrome and NASH replicated this pattern of expression, further suggesting a metabolic link between hepatic PKM2 and NAFLD. Therefore, we conclude that PKM2 serum and hepatic levels increase in both metabolic syndrome and NAFLD and decrease after RYGB. Thus, PKM2 may represent a new target for monitoring and treatment of NAFLD.

Liver Transplantation and Bariatric Surgery: Timing and Outcomes

Nonalcoholic steatohepatitis (NASH) is projected to become the leading indication for liver transplantation (LT) in the next decade in the United States. Strategies to treat the underlying etiology of NASH, which is almost always obesity, are being pursued. One such strategy is the utilization of bariatric surgery (BS) in the peritransplant period. The use of BS prior to LT could prevent the progression of NASH and abrogate the need for LT. BS at the time of LT or postoperatively has the potential to not only improve obesity-associated conditions such as diabetes, but also the potential to influence the incidence of NASH in the post-LT setting. However, there continues to be no consensus on the use and timing of BS in this patient population. This review aims to discuss the current literature and possible future action.

NAFLD and cardiovascular disease

Nonalcoholic fatty liver disease (NAFLD) is an important cause of chronic hepatic disease and liver transplant in Western societies. The increasing prevalence is related to dietary changes and sedentarism and follows the increasing frequency of obesity and type 2 diabetes mellitus.

Growing evidence of association of NAFLD with cardiovascular diseases (CVD), independent of cardiovascular risk factors, has prompted the clarification of whether the liver is mainly a key-effector or a target-organ of the metabolic disarrangements in the metabolic syndrome. The therapeutic strategies able to alter liver disease progression and, through this, reduce the cardiovascular risk have also been tested in the last 2 decades.

This review focus on the possible interactions between hepatic disease, metabolic syndrome, and CVD, and on their implications for clinical practice.

Role of gut microbiota and oxidative stress in the progression of non-alcoholic fatty liver disease to hepatocarcinoma: Current and innovative therapeutic approaches

Non-alcoholic fatty liver disease (NAFLD) represents the most common chronic liver disease in industrialized countries. NAFLD progresses through the inflammatory phase of non-alcoholic steatohepatitis (NASH) to fibrosis and cirrhosis, with some cases developing liver failure or hepatocellular carcinoma (HCC). Liver biopsy remains the gold standard approach to a definitive diagnosis of NAFLD and the distinction between simple steatosis and NASH. The pathogenesis of NASH is still not clear. Several theories have been proposed ranging from the "Two Hit Theory" to the "Multiple Hit Theory". However, the general consensus is that the gut microbiota, oxidative stress, and mitochondrial damage play key roles in the pathogenesis of NASH. The interaction between the gut epithelia and some commensal bacteria induces the rapid generation of reactive oxygen species (ROS). The main goal of any therapy addressing NASH is to reverse or prevent progression to liver fibrosis/cirrhosis. This problem represents the first "Achilles' heel" of the new molecules being evaluated in most ongoing clinical trials. The second is the inability of these molecules to reach the mitochondria, the primary sites of energy production and ROS generation. Recently, a variety of non-pharmacological and pharmacological treatment approaches for NASH have been evaluated including vitamin E, the thiazolidinediones, and novel molecules related to NASH pathogenesis (including obeticholic acid and elafibranor). Recently, a new isoform of human manganese superoxide dismutase (MnSOD) was isolated and obtained in a synthetic recombinant form designated rMnSOD. This protein has been shown to be a powerful antioxidant capable of mediating ROS dismutation, penetrating biological barriers via its uncleaved leader peptide, and reducing portal hypertension and fibrosis in rats affected by liver cirrhosis. Based on these distinctive characteristics, it can be hypothesized that this novel recombinant protein (rMnSOD) potentially represents a new and highly efficient adjuvant therapy to counteract the progression from NASH to HCC.

Utility of transient elastography (fibroscan) and impact of bariatric surgery on nonalcoholic fatty liver disease (NAFLD) in morbidly obese patients

BACKGROUND

Controlled attenuation parameter (CAP) is a novel, noninvasive technique for assessing hepatic steatosis. However, its role in morbidly obese individuals is unclear. The effect of bariatric surgery on inflammation and fibrosis needs to be explored.

OBJECTIVES

To assess the utility of CAP for assessment of hepatic steatosis in morbidly obese individuals and evaluate the effect of bariatric surgery on hepatic steatosis and fibrosis.

SETTING

A tertiary care academic hospital.

METHODS

Baseline details of anthropometric data, laboratory parameters, FibroScan (XL probe), and liver biopsy were collected. Follow-up liver biopsy was done at 1 year.

RESULTS

Of the 124 patients screened, 76 patients were included; mean body mass index was 45.2 ± 7.1 kg/m². FibroScan success rate was 87.9%. The median liver stiffness measurement (LSM) and CAP were 7.0 (5.0-9.5) kPa and 326.5 (301-360.5) dB/m, respectively. On liver histopathology, severe steatosis and nonalcoholic steatohepatitis were present in 5.3% and 15.8%; significant fibrosis (≥stage 2) and cirrhosis in 39.5% and 2.6%, respectively. Area under receiver operator characteristic curve of LSM for prediction of significant fibrosis (F2-4 versus F0-1) and advanced fibrosis (F3-4 versus F0-2) was .65 (95% confidence interval [CI]: .52-.77) and .83 (95% CI: .72-.94), respectively. The area under receiver operator characteristic curve of CAP for differentiating moderate hepatic steatosis (S2-3 versus S0-1) and severe hepatic steatosis (S3 versus S0-2) was .74 (95% CI: .62-.86) and .82 (95% CI: .73-.91), respectively. At 1-year follow-up, 32 patients underwent liver biopsy. In these patients, there was significant improvement in hepatic steatosis (P = .001), lobular inflammation (P = .033), ballooning (P<.001), and fibrosis (P = .003). Nonalcoholic steatohepatitis was resolved in 3 of 4 (75%) patients. LSM and CAP significantly declined.

CONCLUSIONS

LSM and CAP are feasible and accurate at diagnosing advanced fibrosis and severe hepatic steatosis in morbidly obese individuals. Bariatric surgery is associated with significant improvement in LSM, CAP, steatohepatitis, and fibrosis.

Non-alcoholic fatty liver disease: An expanded review

Non-alcoholic fatty liver disease (NAFLD) encompasses the simple steatosis to more progressive steatosis with associated hepatitis, fibrosis, cirrhosis, and in some cases hepatocellular carcinoma. NAFLD is a growing epidemic, not only in the United States, but worldwide in part due to obesity and insulin resistance leading to liver accumulation of triglycerides and free fatty acids. Numerous risk factors for the development of NAFLD have been espoused with most having some form of metabolic derangement or insulin resistance at the core of its pathophysiology. NAFLD patients are at increased risk of liver-related as well as cardiovascular mortality, and NAFLD is rapidly becoming the leading indication for liver transplantation. Liver biopsy remains the gold standard for definitive diagnosis, but the development of noninvasive advanced imaging, biochemical and genetic tests will no doubt provide future clinicians with a great deal of information and opportunity for enhanced understanding of the pathogenesis and targeted treatment. As it currently stands several medications/supplements are being used in the treatment of NAFLD; however, none seem to be the "magic bullet" in curtailing this growing problem yet. In this review we summarized the current knowledge of NAFLD epidemiology, risk factors, diagnosis, pathogenesis, pathologic changes, natural history, and treatment in order to aid in further understanding this disease and better managing NAFLD patients.

Simultaneous living donor liver transplant with sleeve gastrectomy for metabolic syndrome and NASH-related ESLD-First report from India

Nonalcoholic steatohepatitis (NASH) with morbid obesity and metabolic syndrome is now a common cause of end-stage liver disease (ESLD). These patients are high-risk candidates for liver transplant, and require bariatric surgery to prevent recurrent disease in the new liver. Data reports bariatric surgery after transplant, which maybe difficult because of adhesions between the stomach and liver in living donor liver transplant (LDLT) recipient. We report the first case of combined LDLT with sleeve gastrectomy (SG) from India. A morbidly obese diabetic woman with NASH-related ESLD was planned for combined right lobe LDLT with open SG, in view of failed diet therapy, musculo-skeletal complaints, and restricted mobility. Postoperatively, with liver graft functioning adequately, bariatric diet restrictions resulted in maximum reduction of 25% weight, achieving a target BMI below 30 kg/m2 within 2 months, along with complete cure of diabetes and better ambulation. Thus, combination of LDLT and bariatric surgery in the same sitting is safe and effective in management of metabolic syndrome and associated NASH-related ESLD.

Surgical Treatment of Obesity and Diabetes

Sleeve gastrectomy, gastric bypass, gastric banding, and duodenal switch are the most common bariatric procedures performed worldwide. Ninety-five percent of bariatric operations are performed with minimally invasive laparoscopic technique. Perioperative morbidities and mortalities average around 5% and 0.2%, respectively. Long-term weight loss averages around 15% to 25% or about 80 to 100 lbs (40-50 kg). Comorbidities, including type 2 diabetes, hypertension, dyslipidemia, sleep apnea, arthritis, gastroesophageal reflux disease, and nonalcoholic fatty liver disease, improve or resolve after bariatric surgery.

Duodenal-jejunal bypass normalizes pancreatic islet proliferation rate and function but not hepatic steatosis in hypothalamic obese rats

Modifications in life-style and/or pharmacotherapies contribute to weight loss and ameliorate the metabolic profile of diet-induced obese humans and rodents. Since these strategies fail to treat hypothalamic obesity, we have assessed the possible mechanisms by which duodenal-jejunal bypass (DJB) surgery regulates hepatic lipid metabolism and the morphophysiology of pancreatic islets, in hypothalamic obese (HyO) rats. During the first 5 days of life, male Wistar rats received subcutaneous injections of monosodium glutamate (4 g/kg body weight, HyO group), or saline (CTL). At 90 days of age, HyO rats were randomly subjected to DJB (HyO DJB group) or sham surgery (HyO Sham group). HyO Sham rats were morbidly obese, insulin resistant, hypertriglyceridemic and displayed higher serum concentrations of non-esterified fatty acids (NEFA) and hepatic triglyceride (TG). These effects were associated with higher expressions of the lipogenic genes and fatty acid synthase (FASN) protein content in the liver. Furthermore, hepatic genes involved in β-oxidation and TG export were down-regulated in HyO rats. In addition, these rats exhibited hyperinsulinemia, β-cell hypersecretion, a higher percentage of islets and β-cell area/pancreas section, and enhanced nuclear content of Ki67 protein in islet-cells. At 2 months after DJB surgery, serum concentrations of TG and NEFA, but not hepatic TG accumulation and gene and protein expressions, were normalized in HyO rats. Insulin release and Ki67 positive cells were also normalized in HyO DJB islets. In conclusion, DJB decreased islet-cell proliferation, normalized insulinemia, and ameliorated insulin sensitivity and plasma lipid profile, independently of changes in hepatic metabolism.

Reduction in liver transplant wait-listing in the era of direct-acting antiviral therapy

Direct-acting antiviral (DAA) therapy, recently approved for patients with decompensated cirrhosis (DC) secondary to hepatitis C virus (HCV), is associated with improved hepatic function. We analyzed trends in liver transplant (LT) wait-listing (WL) to explore potential impact of effective medical therapy on WL registration. This is a cohort study using the Scientific Registry of Transplant Recipients database from 2003 to 2015. A total of 47,591 adults wait-listed for LT from HCV, hepatitis B virus (HBV), and nonalcoholic steatohepatitis (NASH) were identified. LT indication was defined as DC if the Model for End-Stage Liver Disease (MELD) at WL was ≥15 or hepatocellular carcinoma (HCC). Era of listing was divided into interferon (IFN; 2003-2010), protease inhibitor (PI; 2011-2013), and direct-acting antiviral (DAA; 2014-2015). Annual standardized incidence rates of WL were analyzed using Poisson regression. Adjusted incidences of LT WL for DC in HCV patients decreased by 5% in the PI era (P = 0.004) and 32% in the DAA era (P < 0.001) compared to the IFN era. Listing for DC in HBV also decreased in the PI (-17%; P = 0.002) and DAA eras (-24%; P < 0.001). Conversely, WL for DC in NASH increased by 41% in the PI era (P < 0.001) and 81% in the DAA era (P < 0.001). WL for HCC in both the HCV and NASH populations increased in both the PI and DAA eras (P < 0.001 for all) whereas HCC WL in HBV remained stable (P > 0.05 for all).

CONCLUSION

The rate of LT WL for HCV complicated by DC has decreased by over 30% in the era of DAA therapy. Further reductions in WL are anticipated with increased testing, linkage to care, and access to DAA therapy. (Hepatology 2017;65:804-812).

Functional Liver Recovery After Bariatric Surgery--a Prospective Cohort Study with the LiMAx Test

BACKGROUND

Bariatric surgery provides long-term weight loss and improvement of obesity-associated diseases such as nonalcoholic steatohepatitis (NASH). Histologic improvement of NASH has been reported in some studies after bariatric surgery. This study was designed to assess the liver function in obese patients as well as its recovery after bariatric surgery with a noninvasive test method.

METHODS

In a prospective cohort study from October 2011 to May 2014, morbidly obese individuals receiving bariatric surgery were investigated for functional liver recovery (n = 34). Liver function was determined by the LiMAx test (enzymatic capacity of cytochrome P450 1A2) preoperatively, 6 and 12 months postoperatively. Liver biopsy specimens were obtained from 18 participants and classified according to the nonalcoholic fatty liver disease (NAFLD) activity score (NAS).

RESULTS

The mean age of participants was 44 years, and the mean body mass index (BMI) was 52 kg/m(2). The mean percent excess BMI loss (%EBMIL) was 53 % after 6 months and 68 % after 1 year. Mean liver function capacity increased significantly from 255 μg/kg/h preoperative to 324 μg/kg/h after 6 months and 342 μg/kg/h after 12 months. A negative correlation was observed between %EBMIL and alteration of liver function capacity in the first 6 months. Finally, the median NAS showed a negative correlation with liver function capacity.

CONCLUSIONS

Bariatric surgery leads to a significant functional recovery of the liver. An initial marked weight loss may negatively influence functional liver recovery.

The increasing burden of potentially preventable liver disease among adult liver transplant recipients: A comparative analysis of liver transplant indication by era in Australia and New Zealand

BACKGROUND

Hepatitis C (HCV), hepatitis B (HBV), alcohol-related liver disease (ALD), and non-alcohol-related fatty liver disease (NAFLD) are leading indications for adult liver transplantation in Australia and New Zealand. However, these diseases are potentially preventable through effective primary and/or secondary prevention strategies. This study evaluates the relative contribution of potentially preventable liver diseases to liver transplant numbers in Australia and New Zealand over time.

METHODS

Prospectively recorded clinical, demographic, and outcome data were collected from the Australian and New Zealand Liver Transplant Registry for all primary adult liver transplants performed in Australia and New Zealand from 1 January 1985 until 31 December 2012. Potentially preventable liver disease was defined as HBV, HCV, NAFLD, ALD, and HCC. The etiology of liver disease leading to liver transplantation and the proportion of preventable liver disease-related liver transplantation was compared between Era 1 (1985-1993), Era 2 (1994-2003), and Era 3 (2004-2012).

RESULTS

Overall, 1252 of 3266 adult primary liver transplants (38.3%) were performed for potentially preventable liver disease. There was a significant increase in the proportion of liver transplants because of preventable liver disease from 21.2% (93 of 439) in Era 1, to 49.8% (623 of 1252) in Era 2 and 63.5% (1000 of 1575) in Era 3 (P < 0.0001). Over time, there was a significant increase in HCV (P < 0.0001), ALD (P = 0.002), and NAFLD (P < 0.0001) as a primary indication for adult liver transplant, whereas HBV has significantly decreased from Era 1 to Era 3 as an indication for transplant (P < 0.0001). The number of transplants performed for HCC also increased across Eras (P < 0.0001), with 84% due to underlying potentially preventable liver disease.

CONCLUSION

Since 2004, the majority of primary adult liver transplants within Australia and New Zealand have been because of potentially preventable liver diseases and the prevalence of these diseases has increased over time. This finding represents an opportunity for clinicians to make a significant impact on the overall burden of advanced liver disease in Australia and New Zealand by improving primary and secondary prevention measures.

Improvements of Glucose and Lipid Metabolism After Jejuno-ileal Circuit Procedure in a Non-obese Diabetic Rat Model

BACKGROUND

In a recent study, we showed a jejuno-ileal circuit (JIC) procedure that effectively improved glucose homeostasis, but the intrinsic mechanism requires further studies. Furthermore, the role of JIC in lipid metabolism is also unknown. Given that adiposity aggravates insulin sensitivity, we hypothesize that the JIC procedure improves fat metabolism and thus further contributes to diabetic remission. The aim of this study was to investigate the effects of JIC surgery on lipid metabolism and glucose homeostasis in a non-obese diabetic rat model.

METHODS

Fourteen high-fat diet and low-dose streptozotocin-induced diabetic rats were randomly divided into JIC and sham-JIC groups. Body weight, food intake, glucose tolerance, insulin resistance, serum lipid parameters, glucagon-like peptide 1 (GLP-1), and adipose-derived hormones were measured. At 12 weeks postoperatively, the expressions of hepatic fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC) were measured by Western blot. The lipid content of liver was assessed by hematoxylin-eosin staining and Oil Red O staining. The enteroendocrine cells in the distal ileum were examined by immunohistochemical staining.

RESULTS

Relative to the sham group, the JIC rats exhibited significant improvements in glucose tolerance, insulin resistance, and dyslipidemia without weight loss, showing increased GLP-1 and adiponectin and decreased leptin. JIC also reduced the expression of FAS and ACC in the liver, exhibited improved hepatic fat content, and raised the levels of GLP-1 and chromogranin A in the distal gut.

CONCLUSIONS

JIC alleviated lipometabolic disorders in hyperglycemic rats, which may contribute to the amelioration of insulin sensitivity and glycemic control.

Treatment of Nonalcoholic Fatty Liver Disease: The Role of Medical, Surgical, and Endoscopic Weight Loss

Nonalcoholic fatty liver disease (NAFLD) represents a rapidly growing cause of chronic liver disease in the United States and is associated with significant morbidity and mortality, including progression to liver cirrhosis and hepatocellular carcinoma. NAFLD comprises a spectrum of liver conditions, ranging from simple steatosis to steatosis with inflammation (steatohepatitis) and progressive fibrosis. Weight loss represents a first line therapeutic modality for the management of NAFLD. Herein, we review the evidence base for medical, surgical, and endoscopic approaches to weight loss and their potential impact on the natural history of NAFLD.

GLP-1: a mediator of the beneficial metabolic effects of bariatric surgery?

There has been increasing interest in the role that gut hormones may play in contributing to the physiological changes produced by certain bariatric procedures, such as Roux-en-Y gastric bypass and sleeve gastrectomy. Here, we review the evidence implicating one such gut hormone, glucagon-like peptide-1, as a mediator of the metabolic benefits of these two procedures.

Subclinical kidney injury before and 1 year after bariatric surgery among adolescents with severe obesity

OBJECTIVE

To assess subclinical kidney injury in adolescents with severe obesity by measuring biomarkers of early kidney disease and to assess changes in the levels of these biomarkers following bariatric procedures.

METHODS

Twenty-two adolescents undergoing bariatric surgery with no microalbuminuria and normal kidney function were selected. Urinary NGAL, IL-18, and KIM-1 were measured at baseline, 6 and 12 months postoperatively. Biomarker levels were compared to 44 age-gender-matched lean controls.

RESULTS

Subjects with obesity had a mean baseline BMI of 48 kg/m(2) that decreased by 34% at 1-year follow-up. Urine NGAL, IL-18, and KIM-1 were significantly elevated in subjects with obesity compared to lean controls at baseline. The obese cohort had a further significant increase in NGAL and KIM-1 at 6 months, followed by decline at 1 year. The overall change in levels of all three biomarkers through 1 year after surgery, however, was not significant compared to baseline.

CONCLUSIONS

Adolescent severe obesity is associated with increased urinary excretion of novel biomarkers of kidney injury, despite no microalbuminuria or decreased kidney function. This subclinical kidney injury persists 1 year after significant weight loss induced by bariatric surgery, suggesting that close, long-term follow-up of kidney status is warranted in these adolescents.

Duodenal jejunal bypass attenuates non-alcoholic fatty liver disease in western diet-obese rats

PURPOSE

To evaluate the effects of duodenal-jejunal bypass (DJB) on serum and hepatic profiles of obese rats fed on a western diet (WD).

METHODS

Twenty eight male Wistar rats were fed a standard rodent chow diet (CTL group) or WD ad libitum. After 10 weeks, WD rats were submitted to sham (WD SHAM) or duodenal-jejunal bypass (WD DJB). Body weight, fat pad depots, glycemia, insulinemia, HOMA-IR, TyG, lipids profile and hepatic analyses were evaluated two months after surgery.

RESULTS

The WD SHAM group presented greater obesity, hyperglycemia, hyperinsulinemia, insulin resistance, hypertriglyceridemia and hepatic steatosis than the CTL group. WD DJB rats presented decreased serum glucose and insulin resistance, when compared to WD SHAM animals, without changes in insulinemia. In addition, DJB surgery normalized serum TG and attenuated TG accumulation and steatosis in the liver of the WD DJB group. Hepatic ACC and FAS protein expressions were similar in all groups.

CONCLUSION

Duodenal-jejunal bypass attenuates hepatic parameters of non-alcoholic fatty liver disease in obese rats fed on a western diet.

Non-alcoholic fatty liver disease as a cause and a consequence of metabolic syndrome

Metabolic syndrome is a cluster of metabolic abnormalities that identifies people at risk of diabetes and cardiovascular disease, whereas non-alcoholic fatty liver disease (NAFLD) is defined as a disorder with excess fat in the liver due to non-alcoholic causes. Two key components of metabolic syndrome, glucose and triglycerides, are overproduced by the fatty liver. The liver is therefore a key determinant of metabolic abnormalities. The prevalence of both metabolic syndrome and NAFLD increases with obesity. Other acquired causes for both disorders include excessive intake of simple sugars and physical inactivity. Both disorders predict type 2 diabetes, cardiovascular disease, non-alcoholic steatohepatitis (NASH), and hepatocellular carcinoma. Because metabolic syndrome can be defined in many different ways, NAFLD might be a more direct predictor of these diseases. Half of people with NAFLD carry at least one variant (G) allele at rs738409 in the PNPLA3 gene, which is associated with high liver fat content. Steatosis in PNPLA3-associated NAFLD is not accompanied by features of metabolic syndrome. All forms of NAFLD increase the risk of NASH, cirrhosis, and hepatocellular carcinoma.

Risk of cardiovascular, cardiac and arrhythmic complications in patients with non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) has emerged as a public health problem of epidemic proportions worldwide. Accumulating clinical and epidemiological evidence indicates that NAFLD is not only associated with liver-related morbidity and mortality but also with an increased risk of coronary heart disease (CHD), abnormalities of cardiac function and structure (e.g., left ventricular dysfunction and hypertrophy, and heart failure), valvular heart disease (e.g., aortic valve sclerosis) and arrhythmias (e.g., atrial fibrillation). Experimental evidence suggests that NAFLD itself, especially in its more severe forms, exacerbates systemic/hepatic insulin resistance, causes atherogenic dyslipidemia, and releases a variety of pro-inflammatory, pro-coagulant and pro-fibrogenic mediators that may play important roles in the pathophysiology of cardiac and arrhythmic complications. Collectively, these findings suggest that patients with NAFLD may benefit from more intensive surveillance and early treatment interventions to decrease the risk for CHD and other cardiac/arrhythmic complications. The purpose of this clinical review is to summarize the rapidly expanding body of evidence that supports a strong association between NAFLD and cardiovascular, cardiac and arrhythmic complications, to briefly examine the putative biological mechanisms underlying this association, and to discuss some of the current treatment options that may influence both NAFLD and its related cardiac and arrhythmic complications.

Obesity-associated nonalcoholic fatty liver disease

Obesity is strongly associated with the prevalence of nonalcoholic fatty liver disease (NAFLD) in adult and pediatric populations. Nutrition, physical activity, and behavioral modifications are critical components of the treatment regimen for all obese patients with NAFLD. Bariatric surgeries that affect or restrict the flow of food through the gastrointestinal tract may improve liver histology in morbidly obese patients with nonalcoholic steatohepatitis (NASH), although randomized clinical trials and quasi-randomized clinical studies are lacking. Early detection of NASH and hepatic fibrosis using noninvasive biochemical and imaging markers that may replace liver biopsy is the current challenge.

Endoscopic duodenal-jejunal bypass liner rapidly improves plasma parameters of nonalcoholic fatty liver disease

Bariatric surgery reduces nonalcoholic fatty liver disease (NAFLD). We investigated the effects of duodenal-jejunal bypass liner (DJBL), nonsurgical bariatric device, on plasma parameters of NAFLD. Seventeen obese subjects with type 2 diabetes received the DJBL for 24 weeks. Before, during, and after DJBL implantation, we determined plasma levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), γ-glutamyltransferase (γ-GT), albumin, caspase-cleaved cytokeratin-18 (CK-18), and liver fatty acid-binding protein (L-FABP). At baseline, subjects had increased levels of AST (35 ± 4 IU/L), ALT (54 ± 5 IU/L), and γ-GT (66 ± 14 IU/L), compared with healthy individuals; subjects' mean concentrations of caspase-cleaved CK-18 and L-FABP were 214.4 ± 35.6 U/L and 29.3 ± 2.6 ng/mL, respectively. Three months after implantation of DJBL, all NAFLD-related parameters had decreased from baseline (AST, 28 ± 3 IU/L; ALT, 32 ± 2 IU/L; γ-GT, 44 ±7 IU/L; caspase-cleaved CK-18, 140.6 ± 16.3U/L; and L-FABP, 18.2 ± 1.5 ng/mL; all P < .05). After 6 months, levels of ALT and γ-GT had further decreased (ALT, 28 ± 2 IU/L and γ-GT, 35 ± 5 IU/L), whereas levels of AST, caspase-cleaved CK-18, and L-FABP had stabilized (P = not significant). Six months after DJBLs were removed, levels of ALT (37 ± 3 IU/L), γ-GT (42 ± 5 IU/L), and caspase-cleaved CK-18 (124.5 ± 12.5U/L) were still reduced (P < .05), whereas AST and L-FABP had returned to near baseline levels (P = not significant). Therefore, in obese subjects, DJBL reduces plasma parameters of NAFLD. ClinicalTrials.gov, Number: NCT00985114.

The role of gastrointestinal hormones in hepatic lipid metabolism

Hepatocellular accumulation of free fatty acids (FFAs) in the form of triglycerides constitutes the metabolic basis for the development of nonalcoholic fatty liver disease (NAFLD). Recent data demonstrate that excess FFA hepatocyte storage is likely to lead to lipotoxicity and hepatocyte apoptosis. Hence, FFA-mediated hepatocyte injury is a key contributor to the pathogenesis of nonalcoholic steatohepatitis (NASH). Nonalcoholic steatohepatitis, obesity, type 2 diabetes, essential hypertension, and other common medical problems together comprise metabolic syndrome. Evidence suggests that peptide hormones from the L cells of the distal small intestine, which comprise the core of the enteroendocrine system (EES), play two key roles, serving either as incretins, or as mediators of appetite and satiety in the central nervous system. Recent data related to glucagon-like peptide-1 (GLP-1) and other known L-cell hormones have accumulated due to the increasing frequency of bariatric surgery, which increase delivery of bile salts to the hindgut. Bile acids are a key stimulus for the TGR5 receptor of the L cells. Enhanced bile-salt flow and subsequent EES stimulation may be central to elimination of hepatic steatosis following bariatric surgery. Although GLP-1 is a clinically relevant pharmacological analogue that drives pancreatic β-cell insulin output, GLP-1 analogues also have independent benefits via their effects on hepatocellular FFA metabolism. The authors also discuss recent data regarding the role of the major peptides released by the EES, which promote satiety and modulate energy homeostasis and utilization, as well as those that control fat absorption and intestinal permeability. Taken together, elucidating novel functions for EES-related peptides and pharmacologic development of peptide analogues offer potential far-ranging treatment for obesity-related human disease.

Epigenetic regulation of hepatocellular carcinoma in non-alcoholic fatty liver disease

Emerging evidence that epigenetics converts alterations in nutrient and metabolism into heritable pattern of gene expression has profound implications in understanding human physiology and diseases. Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome including obesity and diabetes which elevate the risk of hepatocellular carcinoma (HCC) especially in male. This review focuses on the molecular connections between metabolic dysfunction and aberrant epigenetic alterations in the development of HCC in NAFLD. The metabolites derived from excessive insulin, glucose and lipid may perturb epigenetic gene regulation through DNA methylation, histone modifications, and RNA interference, leading to activation of pro-inflammatory signaling and deregulation of metabolic pathways. The interplay and crosstalk of chromatin-modifying enzymes, microRNAs, signaling pathways and the downstream transcription factors result in epigenomic reprogramming that drives hepatocellular transformation. The interactions between sex hormone pathways and the epigenetic machineries that influence chromatin states in NAFLD provide potential molecular mechanisms of gender disparity in HCC. A deeper understanding of these connections and comprehensive molecular catalog of hepatocarcinogenesis may shed light in the identification of druggable epigenetic targets for the prevention and treatment of HCC in obese or diabetic patients.

Changes in post-prandial glucose and pancreatic hormones, and steady-state insulin and free fatty acids after gastric bypass surgery

BACKGROUND

Changes in the multiple mechanisms that regulate glucose metabolism after gastric bypass (RYGB) are still being unveiled. The objective of this study was to compare the changes of glucose and pancreatic hormones [C-peptide, glucagon, and pancreatic polypeptide (PP)] during a meal tolerance test (MTT) and steady-state insulin and free fatty acid (FFA) concentrations during euglycemic-hyperinsulinemic clamp 14 days and 6 months after RYGB in morbidly obese nondiabetic patients.

METHODS

Two groups were studied at baseline and at 14 days: the RYGB followed by caloric restriction group (RYGB, n = 12) and the equivalent caloric restriction alone group (Diet, n = 10), to control for energy intake and weight loss. The RYGB group was studied again at 6 months to assess the changes after substantial weight loss. During MTT, the early and overall changes in glucose and pancreatic hormone concentrations were determined, and during the clamp, steady-state insulin and FFA concentrations were assessed.

RESULTS

After 14 days, RYGB patients had enhanced postprandial glucose, C-peptide, and glucagon responses, and decreased postprandial PP concentrations. Steady-state insulin concentrations were decreased at 14 days only in RYGB patients, and FFA increased in both groups. Six months after RYGB and substantial weight loss, the decrease in insulin concentrations during clamp persisted, and there were further changes in postprandial glucose and glucagon responses. FFA concentrations during clamp were significantly lower at 6 months, relative to presurgical values.

CONCLUSIONS

In morbidly obese nondiabetic patients, RYGB produces early changes in postmeal glucose, C-peptide, glucagon, and PP responses, and it appears to enhance insulin clearance early after RYGB and improve insulin sensitivity in adipose tissue at 6 months postsurgery. The early changes cannot be explained by caloric restriction alone.

Increasing whole grain intake as part of prevention and treatment of nonalcoholic Fatty liver disease

In conjunction with the rise in rates of obesity, there has been an increase in the rate of nonalcoholic fatty liver disease (NAFLD). While NAFLD at least partially originates from poor diet, there is a lack of nutritional recommendations for patients with suspected or confirmed diagnosis of NAFLD, beyond eating a healthy diet, increasing physical activity, and emphasising weight loss. The limited current literature suggests that there may be opportunities to provide more tailored dietary advice for people diagnosed with or at risk of NAFLD. Epidemiological studies consistently find associations between whole grain intake and a reduced risk of obesity and related diseases, yet no work has been done on the potential of whole grains to prevent and/or be a part of the treatment for fatty liver diseases. In this review, we examine the potential and the current evidence for whole grains having an impact on NAFLD. Due to their nutrient and phytochemical composition, switching from consuming mainly refined grains to whole grains should be considered as part of the nutritional guidelines for patients diagnosed with or at risk for fatty liver disease.

Gastrointestinal complications of obesity: non-alcoholic fatty liver disease (NAFLD) and its sequelae

Obesity is a major risk factor for malign and non-malign diseases of the gastrointestinal tract. Non-alcoholic fatty liver disease (NAFLD) is an outstanding example for the complex pathophysiology of the metabolic system and represents both source and consequence of the metabolic syndrome. NAFLD has a growing prevalence and will become the leading cause of advanced liver disease and cirrhosis. Obesity has a negative impact on NAFLD at all aspects and stages of the disease. The growing epidemic will strain health care resources and demands new concepts for prevention, screening and therapeutic approaches. A better understanding of the interplay of liver, gut and hormonal system is necessary for new insights in the underlying mechanisms of NAFLD and the metabolic syndrome including obesity. Identification of patients at risk for progressive liver disease will allow a better adaption of treatment strategies.

Molecular mechanisms and the role of saturated fatty acids in the progression of non-alcoholic fatty liver disease

The steady rise in Western obesity rates has been closely linked to significant increases in a multitude of accompanying health problems including non-alcoholic fatty liver disease (NAFLD). NAFLD severity ranges from simple steatosis to acute steatohepatitis, but the molecular mechanisms controlling progression of this disease are poorly understood. Recent literature suggests that elevated free fatty acids (FFAs), especially saturated FFAs, may play an important role in lipotoxic mechanisms, both in experimental models and in NAFLD patients. This review highlights important cellular pathways involved in hepatic lipotoxicity and how the degree of intrahepatic lipid saturation controls cell fate in response to an elevated FFA load. Relevant cellular processes that have been causally linked to lipid-induced apoptosis, known as lipoapoptosis, include endoplasmic reticulum (ER) stress, oxidative stress, mitochondrial dysfunction, and Jun N-terminal kinase (JNK) signaling. In contrast, increased triglyceride synthesis has been shown to have a protective effect against lipotoxicity, despite being one of the hallmark traits of NAFLD. Developing a more nuanced understanding of the molecular mechanisms underlying NAFLD progression will lead to more targeted and effective therapeutics for this increasingly prevalent disease, which to date has no proven pharmacologic treatment to prevent or reverse its course.