New treatments for nonalcoholic fatty liver disease

Effect of N-acetyl cysteine in children with metabolic dysfunction-associated steatotic liver disease-A pilot study

BACKGROUND

Prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as nonalcoholic fatty liver disease (NAFLD), and its sequelae of more severe forms such as metabolic dysfunction-associated steatohepatitis (MASH) is rapidly increasing in children with the rise in obesity. Successful and sustainable treatments for MASLD are lacking in children. We determined the therapeutic effect of N-acetyl cysteine (NAC) on biomarkers of oxidative stress, inflammation and insulin resistance (IR), liver enzymes, liver fat fraction (LFF) and liver stiffness (LS) in children with obesity and biopsy-confirmed MASLD.

METHODS

Thirteen children (n = 13; age: 13.6 ± 2.8 years; NAS score >2) underwent a double-blind, placebo-controlled trial of NAC (either 600 or 1200 mg NAC/day) or placebo for 16 weeks. Measurements included LFF (magnetic resonance imaging), LS (ultrasound elastography), and body composition. Erythrocyte glutathione (GSH), liver enzymes, insulin, glucose, adiponectin, high-sensitivity c-reactive protein (hs-CRP), and interleukin-6 (IL-6) were also measured. homeostasis model assessment for insulin resistance (HOMA-IR) was calculated.

RESULTS

Sixteen-week NAC treatment improved (baseline adjusted between-group p < .05 for all) markers of inflammation (IL-6 and hs-CRP), oxidative stress (GSH), and IR (HOMA-IR) and reduced liver enzymes, LFF and LS. Body weight and body composition did not show beneficial changes.

CONCLUSIONS

Sixteen-week NAC treatment was well tolerated in children with obesity and MASLD and led to improvements in oxidative stress, inflammation and IR and liver outcomes. The results from this pilot study support further investigation of NAC as a therapeutic agent in children with MASLD.

Neonatal intake of oleanolic acid attenuates the subsequent development of high fructose diet-induced non-alcoholic fatty liver disease in rats

Dietary manipulations during the early postnatal period are associated with the development of metabolic disorders including non-alcoholic fatty liver disease (NAFLD) or long-term protection against metabolic dysfunction. We investigated the potential hepatoprotective effects of neonatal administration of oleanolic acid (OA), a phytochemical, on the subsequent development in adulthood, of dietary fructose-induced NAFLD. Male and female suckling rats (n=112) were gavaged with; distilled water (DW), OA (60 mg/kg), high fructose solution (HF; 20% w/v) and OA+HF (OAHF) for 7 days. The rats were weaned onto normal rat chow on day 21 up to day 55. From day 56, half of the rats in each treatment group were continued on plain water or HF as drinking fluid for 8 weeks. Hepatic lipid accumulation and hepatic histomorphometry were then determined. Fructose consumption in adulthood following neonatal fructose intake (HF+F) caused a 47-49% increase in hepatic lipid content of both male and female rats (P<0.05). However, fructose administered in adulthood only, caused a significant increase (P<0.05) in liver lipid content in females only. NAFLD activity scores for inflammation and steatosis were higher in the fructose-fed rats compared with other groups (P<0.05). Steatosis, low-grade inflammation and fibrosis were observed in rats that received HF+F. NAFLD area fraction for fibrosis was three times higher in rats that received fructose neonatally and in adulthood compared with the rats in the negative control group (P<0.05). Treatment with OA during a critical window of developmental plasticity in rats prevented the development of fructose-induced NAFLD.

PPARgamma Agonists: Potential as Therapeutics for Neovascular Retinopathies

The angiogenic, neovascular proliferative retinopathies, proliferative diabetic retinopathy (PDR), and age-dependent macular degeneration (AMD) complicated by choroidal neovascularization (CNV), also termed exudative or “wet” AMD, are common causes of blindness. The antidiabetic thiazolidinediones (TZDs), rosiglitazone, and troglitazone are PPARγ agonists with demonstrable antiproliferative, and anti-inflammatory effects, in vivo, were shown to ameliorate PDR and CNV in rodent models, implying the potential efficacy of TZDs for treating proliferative retinopathies in humans. Activation of the angiotensin II type 1 receptor (AT1-R) propagates proinflammatory and proliferative pathogenic determinants underlying PDR and CNV. The antihypertensive dual AT1-R blocker (ARB), telmisartan, recently was shown to activate PPARγ and improve glucose and lipid metabolism and to clinically improve PDR and CNV in rodent models. Therefore, the TZDs and telmisartan, clinically approved antidiabetic and antihypertensive drugs, respectively, may be efficacious for treating and attenuating PDR and CNV humans. Clinical trials are needed to test these possibilities.

Local RAS

The concept of a circulating RAS is well established and known to play an endocrine role in the regulation of fluid homeostasis (see Section 4.1, Chapter 4). However, it is more appropriate to view the RAS in the contemporary notion as an “angiotensin-generating system”, which consists of angiotensinogen, angiotensin-generating enzymes, and angiotensins, as well as their receptors. Some RASs can be termed as “complete”, having renin and ACE involved in the biosynthesis of angiotensin II peptide, i.e. in a renin and/or ACE-dependent manner which is exemplified in the circulating RAS. On the other hand, some RAS can be termed as “partial”, having alternate enzymes to renin and ACE, such as chymase and ACE2 (see Section 4.3, Chapter 4) available for the generation of angiotensin II and other bioactive angiotensin peptides in the biosynthetic cascade, i.e. in a renin and/or ACE-independent manner. Complete vs. partial RASs can be exemplified in the so-called intrinsic angiotensin-generating system or local RAS; for example, a local and functional RAS with renin and ACE-dependent but a renin-independent pathway have been indentified in the pancreas and carotid body, respectively. In the past two decades, local RASs have gained increasing recognition especially with regards to their clinical importance. Distinct from the circulating RAS, these functional local RASs exist in such diverse tissues and organs as the pancreas, liver, intestine, heart, kidney, vasculature, carotid body, and adipose, as well as the nervous, reproductive, and digestive systems. Taken into previous findings from our laboratory and others together, Table 5.1 is a summary of some recently identified local RASs in various levels of tissues and organs.

Nonalcoholic fatty liver disease: pathology and pathogenesis

Nonalcoholic fatty liver disease (NAFLD) is recognized as the leading cause of chronic liver disease in adults and children. NAFLD encompasses a spectrum of liver injuries ranging from steatosis to steatohepatitis with or without fibrosis. Fibrosis may progress to cirrhosis and complications including hepatocellular carcinoma. Histologic findings represent the complexity of pathophysiology. NAFLD is closely associated with obesity and is most closely linked with insulin resistance; the current Western diet, high in saturated fats and fructose, plays a significant role. There are several mechanisms by which excess triglycerides are acquired and accumulate in hepatocytes. Formation of steatotic droplets may be disordered in NAFLD. Visceral adipose tissue dysfunction in obesity and insulin resistance results in aberrant cytokine expression; many cytokines have a role in liver injury in NAFLD. Cellular stress and immune reactions, as well as the endocannabinoid system, have been implicated in animal models and in some human studies.

Genetic and epigenetic changes associated with cholangiocarcinoma: from DNA methylation to microRNAs

Cholangiocarcinomas are malignant epithelial liver tumors arising from the intra- and extra-hepatic bile ducts. Little is known about the molecular development of this disease, and very few effective treatment options are available. Thus, prognosis is poor. Genetic and epigenetic changes play an integral role in the neoplastic transformation of human cells to their malignant counterparts. This review summarizes some of the more prevalent genetic alterations (by microRNA expression) and epigenetic changes (hypermethylation of specific gene promoters) that are thought to contribute to the carcinogenic process in cholangiocarcinoma.

Genetic and epigenetic changes associated with cholangiocarcinoma: From DNA methylation to microRNAs

Cholangiocarcinomas are malignant epithelial liver tumors arising from the intra- and extra-hepatic bile ducts. Little is known about the molecular development of this disease, and very few effective treatment options are available. Thus, prognosis is poor. Genetic and epigenetic changes play an integral role in the neoplastic transformation of human cells to their malignant counterparts. This review summarizes some of the more prevalent genetic alterations (by microRNA expression) and epigenetic changes (hypermethylation of specific gene promoters) that are thought to contribute to the carcinogenic process in cholangiocarcinoma.

Pioglitazone treatment increases whole body fat but not total body water in patients with non-alcoholic steatohepatitis

BACKGROUND/AIMS

Non-Alcoholic Steatohepatitis (NASH) is a chronic liver disease frequently associated with insulin resistance and type 2 diabetes mellitus (T2DM). Pioglitazone reverses the metabolic and histological abnormalities of patients with impaired glucose tolerance or T2DM and NASH, but also leads to weight gain. To understand the nature of weight gain associated with pioglitazone treatment in NASH we analyzed 35 patients who completed tests for determination of whole body fat (WBF) and total body water (TBW).

METHODS

Twenty-one patients received pioglitazone and 14 placebo in a double-blind, randomized fashion for a period of 6 months. WBF and TBW were measured before and after treatment using DXA, a water dilution technique and bioimpedance.

RESULTS

Pioglitazone increased body weight (from 93.6+/-4.2 to 96.1+/-4.5 kg, p<0.003) and WBF measured with DXA (from 32.9+/-2.1 to 35.4+/-2.5 kg, p<0.002) while no changes were seen with placebo. Total body water was not altered significantly either after pioglitazone (from 45.4+/-2.3 to 45.6+/-2.7 l, p=NS) or placebo. Muscle hydration and extracellular water were unchanged both by pioglitazone and placebo treatments.

CONCLUSIONS

Six months of pioglitazone treatment in patients with NASH is associated with weight gain that is attributable to an increase in adipose tissue mass and not to water retention.

Metabolic syndrome and mitochondrial function: molecular replacement and antioxidant supplements to prevent membrane peroxidation and restore mitochondrial function

Metabolic syndrome consists of a cluster of metabolic conditions, such as hypertriglyceridemia, hyper-low-density lipoproteins, hypo-high-density lipoproteins, insulin resistance, abnormal glucose tolerance and hypertension, that-in combination with genetic susceptibility and abdominal obesity-are risk factors for type 2 diabetes, vascular inflammation, atherosclerosis, and renal, liver and heart disease. One of the defects in metabolic syndrome and its associated diseases is excess cellular oxidative stress (mediated by reactive oxygen and nitrogen species, ROS/RNS) and oxidative damage to mitochondrial components, resulting in reduced efficiency of the electron transport chain. Recent evidence indicates that reduced mitochondrial function caused by ROS/RNS membrane oxidation is related to fatigue, a common complaint of MS patients. Lipid replacement therapy (LRT) administered as a nutritional supplement with antioxidants can prevent excess oxidative membrane damage, restore mitochondrial and other cellular membrane functions and reduce fatigue. Recent clinical trials have shown the benefit of LRT plus antioxidants in restoring mitochondrial electron transport function and reducing moderate to severe chronic fatigue. Thus LRT plus antioxidant supplements should be considered for metabolic syndrome patients who suffer to various degrees from fatigue.

Nonalcoholic fatty liver disease (NAFLD): Approach in the adolescent patient

Nonalcoholic fatty liver disease (NAFLD) is a spectrum of liver disease whose hallmark is the accumulation of large-droplet fat in hepatocytes. This metabolic disorder occurs mainly in overweight or obese individuals. The disease mechanism involves hyperinsulinemia and hepatic insulin resistance, not ethanol abuse. NAFLD may be the hepatic manifestation of the "metabolic syndrome" classically associated with type 2 diabetes mellitus and cardiovascular disease. NAFLD ranges from simple steatosis, which is the least rapidly progressing disorder, to nonalcoholic steatohepatitis to cirrhosis, which can evolve to chronic liver failure. The high prevalence of NAFLD in children has been recognized only in the past 5 to 10 years, as rates of childhood obesity have soared. Accordingly, the best strategies for diagnosis and treatment of childhood NAFLD are a work in progress and remain controversial. Weight reduction through a healthy diet and regular medium-intensity exercise is the mainstay of current treatment. Few research data are available to guide pharmacologic therapy. Certain points regarding management of childhood NAFLD require emphasis: It is a serious liver disease that requires detailed clinical investigation. Other liver diseases causing fatty liver and/or abnormal liver tests, notably Wilson disease and chronic viral hepatitis, need to be excluded. Liver biopsy can provide critical diagnostic and staging information. Associated genetic or endocrine disorders need to be identified. Treatment should begin with a low-glycemic index diet that provides adequate nutrients but is low in harmful fats and eliminates foods causing postprandial hyperglycemia. Initially, this can target two to three problem foods so that it is easy for the adolescent to follow. Regular exercise suited to the capabilities and interests of the teenager should be added to the daily routine. Where possible, a team approach, including a dietician and psychologist, should be utilized, as adolescents do better in a supportive atmosphere. Optimal drug treatment requires further research: current front-runners are vitamin E and metformin. The roles of drugs that alter appetite and bariatric surgery for adolescents with NAFLD have not been determined.