Non-alcoholic fatty liver disease in diabetes: When to refer to the hepatologist?

The impact of gut microbiome-targeted therapy on liver enzymes in patients with nonalcoholic fatty liver disease: an umbrella meta-analysis

CONTEXT

Nonalcoholic fatty liver disease (NAFLD) is considered the leading cause of chronic liver disease worldwide. To date, no confirmed medication is available for the treatment of NAFLD. Previous studies showed the promising effects of gut microbiome-targeted therapies; however, the results were controversial and the strength of the evidence and their clinical significance remained unclear.

OBJECTIVES

This umbrella study summarizes the results of meta-analyses investigating the effects of probiotics, prebiotics, and synbiotics on liver enzymes in the NAFLD population.

DATA SOURCE

A comprehensive search of the PubMed, Scopus, Web of Science, and Cochrane Library databases was done up to December 20, 2022, to find meta-analyses on randomized control trials reporting the effects of gut microbial therapy on patients with NAFLD.

DATA EXTRACTION

Two independent investigators extracted data on the characteristics of meta-analyses, and any discrepancies were resolved by a third researcher. The AMSTAR2 checklist was used for evaluating the quality of studies.

DATA ANALYSIS

A final total of 15 studies were included in the analysis. Results showed that microbiome-targeted therapies could significantly reduce levels of alanine aminotransferase (ALT; effect size [ES], -10.21; 95% confidence interval [CI], -13.29, -7.14; P < 0.001), aspartate aminotransferase (AST; ES, -8.86; 95%CI, -11.39, -6.32; P < 0.001), and γ-glutamyltransferase (ES, -5.56; 95%CI, -7.92, -3.31; P < 0.001) in patients with NAFLD. Results of subgroup analysis based on intervention showed probiotics could significantly reduce levels of AST (ES, -8.69; 95%CI, -11.01, -6.37; P < 0.001) and ALT (ES, -9.82; 95%CI, -11.59, -8.05; P < 0.001). Synbiotics could significantly reduce levels of AST (ES, -11.40; 95%CI, -13.91, -8.88; P < 0.001) and ALT (ES, -11.87; 95%CI, -13.80, -9.95; P < 0.001). Prebiotics had no significant effects on AST and ALT levels (ES, -2.96; 95%CI, -8.12, 2.18, P = 0.259; and ES, -4.69; 95%CI, -13.53, 4.15, P = 0.299, respectively).

CONCLUSION

Gut microbiome-targeted therapies could be a promising therapeutic approach in the improvement of hepatic damage in patients with NAFLD. However, more studies are needed to better determine the best bacterial strains, duration of treatment, and optimum dosage of gut microbiome-targeted therapies in the treatment of the NAFLD population.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42022346998.

Epidemiology of NAFLD - Focus on diabetes

There is increasing appreciation of the complex interaction between nonalcoholic fatty liver disease (NAFLD) with type 2 diabetes (T2D) and insulin resistance. Not only is the prevalence of NAFLD disease high among patients with T2D, the liver disease is also more progressive. Currently, the global prevalence of NAFLD in the general population (2016-2019) is 38 %. The prevalence of T2D among those with NAFLD is approximately 23 % while the prevalence of NAFLD among those with T2D can be as high as 70 %. The prevalence of nonalcoholic steatohepatitis (NASH) is approximately 7 % in the general population and 37 % among patients with T2D. Globally, the MENA and Latin America regions of the world appear to have the highest burden of both NAFLD and T2D. Compared to those with NAFLD but without T2D, those with NAFLD and T2D are at a much higher risk for disease progression to cirrhosis and for decompensated cirrhosis, hepatocellular carcinoma, and all-cause mortality. Given that highly effective new treatments are available for T2D, high risk NAFLD with T2D should be considered for these regimens. This requires implementation of risk stratification algorithms in the primary care and endocrinology practices to identify those patients at highest risk for adverse outcomes.

Calorie Restriction Using High-Fat/Low-Carbohydrate Diet Suppresses Liver Fat Accumulation and Pancreatic Beta-Cell Dedifferentiation in Obese Diabetic Mice

In diabetes, pancreatic β-cells gradually lose their ability to secrete insulin with disease progression. β-cell dysfunction is a contributing factor to diabetes severity. Recently, islet cell heterogeneity, exemplified by β-cell dedifferentiation and identified in diabetic animals, has attracted attention as an underlying molecular mechanism of β-cell dysfunction. Previously, we reported β-cell dedifferentiation suppression by calorie restriction, not by reducing hyperglycemia using hypoglycemic agents (including sodium-glucose cotransporter inhibitors), in an obese diabetic mice model (db/db). Here, to explore further mechanisms of the effects of food intake on β-cell function, db/db mice were fed either a high-carbohydrate/low-fat diet (db-HC) or a low-carbohydrate/high-fat diet (db-HF) using similar calorie restriction regimens. After one month of intervention, body weight reduced, and glucose intolerance improved to a similar extent in the db-HC and db-HF groups. However, β-cell dedifferentiation did not improve in the db-HC group, and β-cell mass compensatory increase occurred in this group. More prominent fat accumulation occurred in the db-HC group livers. The expression levels of genes related to lipid metabolism, mainly regulated by peroxisome proliferator-activated receptor α and γ, differed significantly between groups. In conclusion, the fat/carbohydrate ratio in food during calorie restriction in obese mice affected both liver lipid metabolism and β-cell dedifferentiation.

Therapeutic treatments for diabetes mellitus-induced liver injury by regulating oxidative stress and inflammation

Diabetes mellitus (DM) is a metabolic disease that affects all systems in the body, including the liver. Numerous studies have reported that chronic DM etiology and pathogenesis complications implicate oxidative stress, generating reactive oxygen species, such as superoxide anions and free radicals. In addition, pro-inflammatory reactions are also underlying functions closely related to oxidative stress that further exacerbate pathological DM states. The liver is especially susceptible to hyperglycemia-induced oxidative stress and the related inflammation. Thus, anti-oxidation and anti-inflammation therapies are promising strategies for treating liver damage. This review summarizes therapeutic treatments attenuating the generation of oxidative stress and pro-inflammation, which also cause DM-induced liver injury. Although the treatments have several impediments to be solved, these remedies may have clinically important implications under the absence of effective drugs for the damaged liver in DM patients.

New anti-diabetic agents for the treatment of non-alcoholic fatty liver disease: a systematic review and network meta-analysis of randomized controlled trials

Objectives

This network meta-analysis aims to compare the efficacy and safety of new anti-diabetic medications for the treatment of non-alcoholic fatty liver disease (NAFLD).

Materials and methods

PubMed and Scopus were searched from inception to 27th March 2022 to identify all randomized controlled trials (RCTs) in NAFLD patients. Outcomes included reductions in intrahepatic steatosis (IHS) and liver enzyme levels. The efficacy and safety of DPP-4 inhibitors, GLP-1 agonists, SGLT-2 inhibitors, and other therapies were indirectly compared using a NMA approach. Unstandardized mean difference (USMD) with 95% confidence intervals (CI) were calculated.

Results

2,252 patients from 31 RCTs were included. "Add-on" GLP-1 agonists with standard of care (SoC) treatment showed significantly reduced IHS compared to SoC alone [USMD (95%CI) -3.93% (-6.54%, -1.33%)]. Surface under the cumulative ranking curve (SUCRA) identified GLP-1 receptor agonists with the highest probability to reduce IHS (SUCRA 88.5%), followed by DPP-4 inhibitors (SUCRA 69.6%) and pioglitazone (SUCRA 62.2%). "Add-on" GLP-1 receptor agonists were also the most effective treatment for reducing liver enzyme levels; AST [USMD of -5.04 (-8.46, -1.62)], ALT [USMD of -9.84 (-16.84, -2.85)] and GGT [USMD of -15.53 (-22.09, -8.97)] compared to SoC alone. However, GLP-1 agonists were most likely to be associated with an adverse event compared to other interventions.

Conclusion

GLP-1 agonists may represent the most promising anti-diabetic treatment to reduce hepatic steatosis and liver enzyme activity in T2DM and NAFLD patients. Nevertheless, longer-term studies are required to determine whether this delays progression of liver cirrhosis in patients with NAFLD and T2DM.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42021259336.1.

Glucagon in type 2 diabetes: Friend or foe?

Hyperglucagonemia is one of the 'ominous' eight factors underlying the pathogenesis of type 2 diabetes (T2D). Glucagon is a peptide hormone involved in maintaining glucose homoeostasis by increasing hepatic glucose output to counterbalance insulin action. Long neglected, the introduction of dual and triple agonists exploiting glucagon signalling pathways has rekindled the interest in this hormone beyond its classic effect on glycaemia. Glucagon can promote weight loss by regulating food intake, energy expenditure, and brown and white adipose tissue functions through mechanisms still to be fully elucidated, thus its role in T2D pathogenesis should be further investigated. Moreover, the role of glucagon in the development of T2D micro- and macro-vascular complications is elusive. Mounting evidence suggests its beneficial effect in non-alcoholic fatty liver disease, while few studies postulated its favourable role in peripheral neuropathy and retinopathy. Contrarily, glucagon receptor agonism might induce renal changes resembling diabetic nephropathy, and data concerning glucagon actions on the cardiovascular system are conflicting. This review aims to summarise the available findings on the role of glucagon in the pathogenesis of T2D and its complications. Further experimental and clinical data are warranted to better understand the implications of glucagon signalling modulation with new antidiabetic drugs.

Chinese patients with type 2 diabetes mellitus and nonalcoholic fatty liver disease have lower serum osteocalcin levels compared to individuals with type 2 diabetes mellitus and no liver disease: a single-center cross-sectional study

PURPOSE

Osteocalcin may benefit nonalcoholic fatty liver disease (NAFLD). The present study aimed to explore the levels of serum osteocalcin in NAFLD in patients with type 2 diabetes mellitus (T2DM).

METHODS

In total, 1026 inpatients diagnosed with T2DM were enrolled in the study. NAFLD was defined according to the working definition of the revised guidelines for the management of NAFLD published by the Chinese Liver Disease Association, and confirmed by abdominal ultrasonography.

RESULTS

The current study found a NAFLD prevalence of 54% in the T2DM population. Subjects with NAFLD had lower concentrations of osteocalcin (8.28-13.99 ng/mL vs. 8.80-16.25 ng/mL, P = 0.001) but similar vitamin D, parathyroid hormone, beta-C-terminal telopeptide of type I collagen and procollagen type 1 N-peptide levels. Osteocalcin levels (OR: 0.956; 95% CI 0.926-0.987) were significantly associated with NAFLD. When all significant clinical indicators were analyzed together, increased BMI (OR: 1.120; 95% CI 1.065-1.178), fasting C-peptide (OR: 1.270; 95% CI 1.089-1.481) and triglycerides (OR: 1.661; 95% CI 1.284-2.148) were associated with a greater risk of NAFLD, while older age (OR: 0.967; 95% CI 0.948-0.986) and high osteocalcin levels (OR: 0.935; 95% CI 0.902-0.969) were related with a decreased risk of NAFLD. For every additional unit of osteocalcin, the patients received 7% deduced odds of NAFLD.

CONCLUSION

Low osteocalcin levels were associated with an increased risk for NAFLD in patients with T2DM.

Holistic management of hepatocellular carcinoma: The hepatologist's comprehensive playbook

Hepatocellular carcinoma (HCC) is a common complication in patients with chronic liver disease and leads to significant morbidity and mortality. Liver disease and liver cancer are preventable by mitigating and managing common risk factors, including chronic hepatitis B and C infection, alcohol use, diabetes, obesity and other components of the metabolic syndrome. The management of patients with HCC requires treatment of the malignancy and adequate control of the underlying liver disease, as preserving liver function is critical for successful cancer treatment and may have a relevant prognostic role independent of HCC management. Hepatologists are the ideal providers to guide the care of patients with HCC as they are trained to identify patients at risk, apply appropriate surveillance strategies, assess and improve residual liver function, evaluate candidacy for transplant, provide longitudinal care to optimize and preserve liver function during and after HCC treatment, survey for cancer recurrence and manage its risk factors, and prevent and treat decompensating events. We highlight the need for a team-based holistic approach to the patient with liver disease and HCC and identify necessary gaps in current care and knowledge.

The presence of diabetic retinopathy closely associated with the progression of non-alcoholic fatty liver disease: A meta-analysis of observational studies

Background and Objective: Although growing evidence indicates that non-alcoholic fatty liver disease is related to diabetic retinopathy (DR), research results significantly vary. Therefore, we conducted a meta-analysis to assess the association between the progression of non-alcoholic fatty liver disease and the onset of DR. Methods: PubMed, Embase, and Cochrane databases were searched until 7 November 2021. Combined odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the association. Results: We identified 18 studies involving 12,757 patients. The pooled effect assessment showed that liver fibrosis was positively correlated with DR (OR = 1.69, 95%CI 1.30-2.20; p < 0.0001); non-alcoholic fatty liver disease was not associated with the risk of DR (OR = 1.15, 95%CI 0.75-1.76; p = 0.51); non-alcoholic fatty liver disease was positively correlated with DR in patients with type 1 diabetes (OR = 2.96, 95%CI 1.48-5.94; p = 0.002). In patients with type 2 diabetes, there was no association between non-alcoholic fatty liver disease and DR (OR = 0.92, 95%CI 0.59-1.43; p = 0.70). Subgroup analysis showed no correlation in both Asian and Caucasian races. Conclusion: There is a significant correlation between liver fibrosis and DR. This suggests that the ocular examination of DR could be helpful in predicting whether patients with non-alcoholic fatty liver disease would progress to liver fibrosis.

Peripheral endothelial and microvascular damage in liver cirrhosis: a systematic review and meta-analysis

OBJECTIVE

This is the first systematic review and meta-analysis of studies using any available functional method to examine differences in peripheral endothelial function between cirrhotic and non-cirrhotic individuals.

METHODS

Literature search involved PubMed, Web-of-Science and Scopus databases, as well as grey literature sources. We included studies in adult subjects evaluating endothelial function with any semi-invasive or non-invasive functional method in patients with and without liver cirrhosis.

RESULTS

From 3378 records initially retrieved, 15 studies with a total of 570 participants were included in the final quantitative meta-analysis. In 6 studies examining endothelial function with flow-mediated-dilatation no differences between patients with cirrhosis and controls were evident (WMD: 1.33, 95%CI [-2.87, 5.53], I² =97%, p<0.00001). Among studies assessing differences in endothelial-dependent or endothelial-independent vasodilation with venous-occlusion-plethysmography, there were no significant differences between the two groups. When pooling all studies together, regardless of the technique used, no significant difference in endothelial function between cirrhotic patients and controls was observed(SMD: 0.79, 95%CI[-0.04, 1.63], I2=94%, p<0.00001).

CONCLUSIONS

No differences in peripheral endothelial function assessed with semi-invasive or non-invasive functional methods exist between cirrhotic and non-cirrhotic subjects. The increasing co-existence of cardiovascular risk factors leading to impaired vascular reactivity in cirrhotic patients may partly explain these findings.

Oral Administration of Bacillus toyonensis Strain SAU-20 Improves Insulin Resistance and Ameliorates Hepatic Steatosis in Type 2 Diabetic Mice

In this study, the ameliorative effects of Bacillus toyonensis-SAU-20 (B. toyo SAU-20), a new probiotic strain isolated and identified by our laboratory from Ageratina adenophora, on the development of insulin resistance and hepatic steatosis in type 2 diabetic (T2DM) mice was investigated. Thirty Specific-pathogen free Kunming (SPFKM) mice were randomly allocated to three groups: control, high fat diet/streptozotocin (HFD/STZ), and HFD/STZ+B. toyo SAU-20 groups with oral administration of B. toyo SAU-20 for 35 days. Biochemistry parameters, glucose tolerance, and insulin resistance were measured in the blood whereas histological analysis, inflammatory cytokines and lipogenic genes in the liver tissues. The results showed that, the levels of serum glucose, lipid profile, mRNA expression of lipogenic related genes and pro-inflammatory cytokines were significantly increased in T2DM mice. However, after B. toyo SAU-20 administration, the elevation of these parameters was significantly suppressed (P<0.05). In addition, the feeding of B. toyo SAU-20 significantly improved the morphological changes of the liver with significant alleviation of dyslipidemia, oxidative stress status and inflammation (P<0.05) indicating the ameliorating effect of B. toyo SAU-20 in hepatic steatosis in T2DM. Therefore, we concluded that, B. toyo SAU-20 alleviated insulin resistance and hepatic steatosis by improving the lipid profiles, antioxidant status and downregulating lipogenic genes as well as pro-inflammation cytokines expression.