The Genetics of Clinical Liver Diseases: Insight into the TM6SF2 E167K Variant

Molecular mechanism and therapeutic significance of essential amino acids in metabolically associated fatty liver disease

Non-alcoholic fatty liver disease (NAFLD), also known as metabolically associated fatty liver disease (MAFLD), is a systemic metabolic disease characterized by lipid accumulation in the liver, lipid toxicity, insulin resistance, intestinal dysbiosis, and inflammation that can progress from simple steatosis to nonalcoholic steatohepatitis (NASH) and even cirrhosis or cancer. It is the most prevalent illness threatening world health. Currently, there are almost no approved drug interventions for MAFLD, mainly dietary changes and exercise to control weight and regulate metabolic disorders. Meanwhile, the metabolic pathway involved in amino acid metabolism also influences the onset and development of MAFLD in the body, and most amino acid metabolism takes place in the liver. Essential amino acids are those amino acids that must be supplemented from outside the diet and that cannot be synthesized in the body or cannot be synthesized at a rate sufficient to meet the body's needs, including leucine, isoleucine, valine (collectively known as branched-chain amino acids), tryptophan, phenylalanine (which are aromatic amino acids), histidine, methionine, threonine and lysine. The metabolic balance of the body is closely linked to these essential amino acids, and essential amino acids are closely linked to the pathophysiological process of MAFLD. In this paper, we will focus on the metabolism of essential amino acids in the body and further explore the therapeutic strategies for MAFLD based on the studies conducted in recent years.

Efficacy of pegylated interferon α-2b plus entecavir therapy and predictors of treatment success in children with chronic hepatitis B

Introduction

Interferon therapy, used in the treatment of chronic hepatitis B (CHB), is one of the means by which patients can achieve a functional cure. Pegylated interferon is currently used in the treatment of CHB. There are two main types of pegylated interferon: α-2b and α-2a.

Methods

This study explored the efficacy, safety, and predictors of treatment response for α-2b plus entecavir among children in a real-world setting.

Results

The study included 76 patients aged 3-18 years, all of whom were treated with interferon α-2b plus entecavir. The mean duration of treatment was 401.99 days, and 31.6% (24/76) of patients achieved HBsAg clearance. Competing risk model analyses showed that children with baseline HBsAg <1500 IU/mL (subdistribution hazard ratio [sHR]=2.643, P=0.022) and a higher baseline alanine aminotransferase (ALT) level (sHR=1.005, P=0.000) had a higher probability of achieving HBsAg clearance during treatment. Conversely, children with a higher hepatitis B virus loading level (sHR=0.835, P=0.043) and age ≥10 years (sHR=0.243, P=0.002) had a lower probability of achieving HBsAg clearance during treatment. A decrease of >1 log10 in HBsAg level (sHR=3.479, P=0.001) at 12 weeks of treatment was associated with a higher probability of achieving surface antigen clearance.

Discussion

These results indicated that interferon plus entecavir therapy is a promising means of achieving HBsAg clearance in children with CHB. Moreover, HBsAg, ALT, virus loading, and age are indicators of treatment success probability.

Biomarkers for Assessing Non-Alcoholic Fatty Liver Disease in Patients with Type 2 Diabetes Mellitus on Sodium-Glucose Cotransporter 2 Inhibitor Therapy

In the current modern era of unhealthy lifestyles, non-alcoholic fatty liver disease (NAFLD) is the most prevalent liver disease and has become a serious global health problem. To date, there is no approved pharmacotherapy for the treatment of NAFLD, and necessary lifestyle changes such as weight loss, diet, and exercise are usually not sufficient to manage this disease. Patients with type 2 diabetes mellitus (T2DM) have a significantly higher risk of developing NAFLD and vice versa. Sodium-glucose cotransporter 2 (SGLT2) inhibitors are antidiabetic agents that have recently been approved for two other indications: chronic kidney disease and heart failure in diabetics and non-diabetics. They are also emerging as promising new agents for NAFLD treatment, as they have shown beneficial effects on hepatic inflammation, steatosis, and fibrosis. Studies in animals have reported favorable effects of SGLT2 inhibitors, and studies in patients also found positive effects on body mass index (BMI), insulin resistance, glucose levels, liver enzymes, apoptosis, and transcription factors. There are some theories regarding how SGLT2 inhibitors affect the liver, but the exact mechanism is not yet fully understood. Therefore, biomarkers to evaluate underlying mechanisms of action of SGLT2 inhibitors on the liver have now been scrutinized to assess their potential as a future in-label therapy for NAFLD. In addition, finding suitable non-invasive biomarkers could be helpful in clinical practice for the early detection of NAFLD in patients. This is crucial for a positive disease outcome. The aim of this review is to provide an overview of the most recent findings on the effects of SGLT2 inhibitors on NAFLD biomarkers and the potential of SGLT2 inhibitors to successfully treat NAFLD.

Interferon-Free Regimens and Direct-Acting Antiviral Agents for Delta Hepatitis: Are We There Yet?

Chronic delta hepatitis is a global health problem. Although a smaller percentage of chronic HBV-infected patients are coinfected with the hepatitis delta virus, these patients have a higher risk of an accelerated progression to fulminant "delta hepatitis", cirrhosis, hepatic decompensation, and hepatocellular carcinoma, putting a financial strain on the healthcare system and increasing the need for a liver transplant. Since its discovery, tremendous efforts have been directed toward understanding the intricate pathogenic mechanisms, discovering the complex viral replication process, the essential replicative intermediates, and cell division-mediated viral spread, which enables virion viability. The consideration of the interaction between HBV and HDV is crucial in the process of developing novel pharmaceuticals. Until just recently, interferon-based therapy was the only treatment available worldwide. This review aims to present the recent advancements in understanding the life cycle of HDV, which have consequently facilitated the development of innovative drug classes. Additionally, we will examine the antiviral strategies currently in phases II and III of development, including bulevirtide (an entry inhibitor), lonafarnib (a prenylation inhibitor), and REP 2139 (an HBsAg release inhibitor).

Advances in genetic variation in metabolism-related fatty liver disease

Metabolism-related fatty liver disease (MAFLD) is the most common form of chronic liver disease in the world. Its pathogenesis is influenced by both environmental and genetic factors. With the upgrading of gene screening methods and the development of human genome project, whole genome scanning has been widely used to screen genes related to MAFLD, and more and more genetic variation factors related to MAFLD susceptibility have been discovered. There are genetic variants that are highly correlated with the occurrence and development of MAFLD, and there are genetic variants that are protective of MAFLD. These genetic variants affect the development of MAFLD by influencing lipid metabolism and insulin resistance. Therefore, in-depth analysis of different mechanisms of genetic variation and targeting of specific genetic variation genes may provide a new idea for the early prediction and diagnosis of diseases and individualized precision therapy, which may be a promising strategy for the treatment of MAFLD.

The TM6SF2 variant as a risk factor for hepatocellular carcinoma development in chronic liver disease patients

Introduction

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers worldwide. A non-synonymous single nucleotide polymorphism (SNP) of the transmembrane 6 superfamily member 2 (TM6SF2) gene is associated with non-alcoholic fatty liver disease. SNPs of the TM6SF2 gene play an important role in the pathogenesis of HCC in alcoholic cirrhosis, but there are limited data regarding other possible etiologies. We aimed to evaluate the role of the rs58542926 polymorphism in the development of HCC in Egyptian chronic liver disease (CLD) patients.

Material and methods

A total of 120 participants, including 40 HCC patients, 40 CLD patients, and 40 healthy controls, were selected. Real-time polymerase chain reaction (RT-PCR) was used to detect the TM6SF2 rs58542926 polymorphism.

Results

There were no significant differences among the three studied groups regarding age (p = 0.06) and gender (p = 0.75). Frequencies of the CT, TT, CT + TT genotypes and the T allele were significantly higher in HCC patients than in the CLD and control groups (p < 0.001, p = 0.005, and p < 0.001, respectively). CLD patients with the CT genotype had a significantly increased risk of HCC development (OR = 4.67, 95% CI: 1.67-12.90). Patients with the TT genotype had a significantly increased risk of HCC (OR = 9.33, 95% CI: 1.72-50.61). Moreover, the T allele was correlated with an increased risk of HCC (OR = 5.44, 95% CI: 2.09-14.17) compared to the C allele.

Conclusions

The TM6SF2 rs58542926 genotype is associated with an increased risk of HCC in the Egyptian population.

Recent advances in lean NAFLD

As the predominant type of chronic liver disease, the growing prevalence of nonalcoholic fatty liver disease (NAFLD) has become a concern worldwide. Although obesity plays the most pivotal role in NAFLD, approximately 10-20% of individuals with NAFLD who are not overweight or obese (BMI < 25 kg/m2, or BMI < 23 kg/m2 in Asians) have "lean NAFLD." Lean individuals with NAFLD have a lower prevalence of diabetes, hypertension, hypertriglyceridemia, central obesity, and metabolic syndrome than nonlean individuals with NAFLD, but higher fibrosis scores and rates of cardiovascular morbidity and all-cause mortality in advanced stages. The pathophysiological mechanisms of lean NAFLD remain poorly understood. Studies have shown that lean NAFLD is more correlated with factors such as environmental, genetic susceptibility, and epigenetic regulation. This review will examine the way in which the research progress and characteristic of lean NAFLD, and explore the function of epigenetic modification to provide the basis for the clinical treatment and diagnosis of lean NAFLD.

Relationships among N,N-dimethylformamide exposure, CYP2E1 and TM6SF2 genes, and non-alcoholic fatty liver disease

OBJECTIVE

This study aimed to examine the relationships among N, N-dimethylformamide (DMF) exposure, cytochrome P4502E1 (CYP2E1) single nucleotide polymorphisms (SNPs) (rs2031920, rs3813867, rs6413432), transmembrane 6 superfamily member 2 (TM6SF2) SNP rs58542926 and non-alcoholic fatty liver disease (NAFLD).

METHODS

Baseline data were collected from participants who were then followed for 5 years in a prospective cohort study. The cohort initially consisted of 802 workers and ultimately included 660 people, all of whom underwent annual occupational health examinations from 2010 to 2015.

RESULTS

The above-threshold group (≥7.3 mg/m³ adjusted relative risk (RR)= 3.620, 95%CI 2.072-6.325) was significantly more likely to develop NAFLD than the below-threshold group (<7.3 mg/m³). The TM6SF2 SNP rs58542926 CT (adjusted RR=3.921, 95% CI 2.329-6.600, P = 0.000) and CT+TT (adjusted RR=4.385, 95% CI 2.639-7.287, P = 0.000) genotypes were risk factors for NAFLD, as compared with the TM6SF2 rs58542926 CC genotype. Each dose group (below-threshold group and above-threshold group) interacting with the genotype of TM6SF2 SNP rs58542926 had an adjusted RR from 7.764 (95% CI 3.272-18.420, P = 0.000) to 24.022 (95% CI 8.971-64.328, P = 0.000). The T allele of rs58542926 in the TM6SF2 gene may be a risk factor for susceptibility to DMF-induced NAFLD.

CONCLUSION

Polymorphisms of TM6SF2 SNP rs58542926 may play an important role in susceptibility to NAFLD after exposure to DMF.

Mitochondrial Mutations and Genetic Factors Determining NAFLD Risk

NAFLD (non-alcoholic fatty liver disease) is a widespread liver disease that is often linked with other life-threatening ailments (metabolic syndrome, insulin resistance, diabetes, cardiovascular disease, atherosclerosis, obesity, and others) and canprogress to more severe forms, such as NASH (non-alcoholic steatohepatitis), cirrhosis, and HCC (hepatocellular carcinoma). In this review, we summarized and analyzed data about single nucleotide polymorphism sites, identified in genes related to NAFLD development and progression. Additionally, the causative role of mitochondrial mutations and mitophagy malfunctions in NAFLD is discussed. The role of mitochondria-related metabolites of the urea cycle as a new non-invasive NAFLD biomarker is discussed. While mitochondria DNA mutations and SNPs (single nucleotide polymorphisms) canbe used as effective diagnostic markers and target for treatments, age and ethnic specificity should be taken into account.

A PDCD1 Role in the Genetic Predisposition to NAFLD-HCC?

Obesity and non-alcoholic fatty liver disease (NAFLD) are contributing to the global rise in deaths from hepatocellular carcinoma (HCC). The pathogenesis of NAFLD-HCC is not well understood. The severity of hepatic steatosis, steatohepatitis and fibrosis are key pathogenic mechanisms, but animal studies suggest altered immune responses are also involved. Genetic studies have so far highlighted a major role of gene variants promoting fat deposition in the liver (PNPLA3 rs738409; TM6SF2 rs58542926). Here, we have considered single-nucleotide polymorphisms (SNPs) in candidate immunoregulatory genes (MICA rs2596542; CD44 rs187115; PDCD1 rs7421861 and rs10204525), in 594 patients with NAFLD and 391 with NAFLD-HCC, from three European centres. Associations between age, body mass index, diabetes, cirrhosis and SNPs with HCC development were explored. PNPLA3 and TM6SF2 SNPs were associated with both progression to cirrhosis and NAFLD-HCC development, while PDCD1 SNPs were specifically associated with NAFLD-HCC risk, regardless of cirrhosis. PDCD1 rs7421861 was independently associated with NAFLD-HCC development, while PDCD1 rs10204525 acquired significance after adjusting for other risks, being most notable in the smaller numbers of women with NAFLD-HCC. The study highlights the potential impact of inter individual variation in immune tolerance induction in patients with NAFLD, both in the presence and absence of cirrhosis.

A Potential Functional Cure in Chinese HBeAg-negative Chronic Hepatitis B Patients Treated with Peg-interferon Alpha-2a

Background and Aims: Data are limited on the use of pegylated-interferon alpha-2a (peg-IFNα) in Chinese patients with chronic hepatitis B virus (HBV) infection (CHB). We evaluated the effectiveness and safety of peg-IFNα in Chinese patients with hepatitis B envelope antigen-negative CHB in routine clinical practice. Methods: In this prospective, multicenter, observational, non-interventional cohort study, patients were assessed for up to 1 year after peg-IFNα treatment cessation. Treating physicians established the dosing and treatment duration according to Chinese clinical practice. Effectiveness of peg-IFNα treatment was measured by the percentage of: patients with HBV DNA <2000 IU/mL and loss of hepatitis B surface antigen (commonly known as HBsAg); HBV DNA level at end of treatment (EOT), and 6 months and 1 year posttreatment; and time course change in quantitative HBV DNA and HBsAg. Results: At EOT, 6 months posttreatment, and 1 year posttreatment, the percentage of patients with HBV DNA <2000 IU/mL was 90.0%, 81.8%, and 82.2%, and that of patients with HBsAg loss was 6.5%, 9.4%, and 9.5%, respectively. The HBV DNA level decreased from 5.61 log IU/mL at baseline to 2.48 log IU/mL at EOT and 2.67 log IU/mL at 1 year posttreatment. The HBsAg level decreased from 3.08 log IU/mL at baseline to 2.24 log IU/mL at EOT and 2.10 log IU/mL at 1 year posttreatment. The incidence of adverse events was 52.0%. Conclusions: Peg-IFNα has the potential to provide functional cure (HBsAg loss) for CHB and is well tolerated in hepatitis B envelope antigen-negative CHB patients in routine clinical practice in China. Clinical Trial Registration: ClinicalTrials.gov (NCT01730508).