Cigarette smoking is a risk factor for the onset of fatty liver disease in nondrinkers: A longitudinal cohort study

The importance of patient engagement in the multimodal treatment of MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD) is often regarded in society as a disease caused by personal lifestyle and dietary choices. Healthcare providers who have empathy and are able to explain the disease trajectory can better engage with people with MASLD and actively work with them to improve their metabolic health on a sustainable basis. Non-invasive tests can assist in this process, but healthcare providers must ensure they explain their advantages and limitations. Discussing and setting lifestyle goals are priorities before initiating specific pharmacological treatment, since living a healthy lifestyle will remain the backbone of the multimodal management of MASLD. In this review, we discuss challenges and opportunities to actively engage with people living with MASLD in a multimodal treatment framework as a healthcare provider.

Risk Factors Related to the Development of Nonalcoholic Fatty Liver: A Systematic Review

Background: Nonalcoholic fatty liver disease (NAFLD) has a major impact on public health owing to its high morbidity and mortality due to its close relationship with several conditions, including metabolic syndrome, cirrhosis, and cancer. Therefore, this review aimed to systematically compile and summarize the scientific literature on early risk factors for NAFLD development. Methods: A systematic review of population-based cohort studies was conducted. Studies reporting the risk factors associated with nonalcoholic steatohepatitis (NASH) and NAFLD were screened. Results: The search yielded 987 unique records, of which 196 articles were selected after title and abstract screening. A total of 39 articles were read in full text after quality analysis using Downs and Black criteria; 10 of the studies were excluded due to heterogeneity or inconclusive results. Finally, 30 publications were included in this systematic review. The review revealed that clinical conditions such as obesity, weight change, psoriasis, polycystic ovary syndrome, diabetes, thyroid disorders, and elevated serum uric acid levels increase the risk of developing nonalcoholic fatty liver. In addition, lifestyle factors such as sedentary behavior, active or passive smoking, poor sleep quality, and consumption of carbonated beverages are associated with this condition. Conclusions: Evidence was found on the association between different clinical and lifestyle risk factors and NAFLD. This supports the need for preventive, diagnostic, and therapeutic strategies to improve the metabolic, hepatic, and oncological outcomes related to this condition.

Fibroblast growth factor 21: update on genetics and molecular biology

PURPOSE OF REVIEW

Since its discovery, most research on fibroblast growth factor 21 (FGF21) has focused on its antihyperglycemia properties. However, attention has recently shifted towards elucidating the ability of FGF21 to lower circulating lipid levels and ameliorate liver inflammation and steatosis. We here discuss the physiology of FGF21 and its role in lipid metabolism, with a focus on genetics, which has up until now not been fully appreciated.

RECENT FINDINGS

New developments have uncovered associations of common small-effect variants of the FGF21 gene, such as the single nucleotide polymorphisms rs2548957 and rs838133, with numerous physiological, biochemical and behavioural phenotypes linked to energy metabolism and liver function. In addition, rare loss-of-function variants of the cellular receptors for FGF21 have been recently associated with severe endocrine and metabolic phenotypes. These associations corroborate the findings from basic studies and preliminary clinical investigations into the therapeutic potential of FGF21 for the treatment of metabolic dysfunction-associated steatotic liver disease (MASLD) and hypertriglyceridemia. Furthermore, recent breakthrough research has begun to dissect mechanisms of a potential FGF21 brain-adipose axis. Such inter-organ communication would be comparable to that seen with other potent metabolic hormones. A deeper understanding of FGF21 could prove to be further beneficial for drug development.

SUMMARY

FGF21 is a potent regulator of lipid and energy homeostasis and its physiology is currently at the centre of investigative efforts to develop agents targeting hypertriglyceridemia and MASLD.

Interplay of Oxidative Stress, Gut Microbiota, and Nicotine in Metabolic-Associated Steatotic Liver Disease (MASLD)

Oxidative stress has been described as one of the main drivers of intracellular damage and metabolic disorders leading to metabolic syndrome, a major health problem worldwide. In particular, free radicals alter lipid metabolism and promote lipid accumulation in the liver, existing in the hepatic facet of metabolic syndrome, the metabolic dysfunction-associated steatotic liver disease (MASLD). Recent literature has highlighted how nicotine, especially if associated with a high-fat diet, exerts a negative effect on the induction and progression of MASLD by upregulating inflammation and increasing oxidative stress, abdominal fat lipolysis, and hepatic lipogenesis. Moreover, considerable evidence shows the central role of intestinal dysbiosis in the pathogenesis of MASLD and the impact of nicotine-induced oxidative stress on the gut microbiome. This results in an intricate network in which oxidative stress stands at the intersection point between gut microbiome, nicotine, and MASLD. The aim of this review is to delve into the molecular mechanisms linking tobacco smoking and MASLD, focusing on nicotine-induced microbiota modifications and their impact on MASLD development.

Nicotine aggravates high-fat diet-induced non-alcoholic fatty liver disease in mice via inhibition of CISD3

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease globally. Growing data suggests that smoking plays an important role in the evolution of NAFLD. CDGSH iron sulfur domain 3 (CISD3) regulates critical biological activities. However, its role in nicotine-associated NAFLD and its underlying mechanisms have not been elucidated. Mice were given a high-fat diet for 10 weeks to induce the development of NAFLD. The results revealed that in mice with NAFLD, nicotine treatment resulted in reduced CISD3 expression, leading to mitochondrial dysfunction and impaired β-oxidation. Notably, exacerbation of hepatic steatosis and inflammatory injury was observed. Furthermore, Cisd3-knockout exacerbated lipid accumulation, aggravating oxidative stress and apoptosis. In conclusion, these results contribute to our knowledge of the function of CISD3 in nicotine-associated NAFLD, revealing the possibility of using CISD3 as a potential molecular target for treating NAFLD.

Smoking, all-cause, and cause-specific mortality in individuals with diabetes in Mexico: an analysis of the Mexico city prospective study

OBJECTIVE

Evidence from low- and middle-income countries regarding the effect of smoking in people with diabetes is lacking. Here, we report the association of smoking with mortality in a large cohort of Mexican adults with diabetes.

METHODS

Participants with diabetes mellitus (self-reported diagnosis, use of antidiabetic medications or HbA1c ≥ 6.5%) aged 35-74 years when recruited into the Mexico City Prospective Study were included. Cox regression confounder-adjusted mortality rate ratios (RRs) associated with baseline smoking status were estimated.

RESULTS

Among 15,975 women and 8225 men aged 35-74 years with diabetes but no other comorbidities at recruitment, 2498 (16%) women and 2875 (35%) men reported former smoking and 2753 (17%) women, and 3796 (46%) men reported current smoking. During a median of 17 years of follow-up there were 5087 deaths at ages 35-74 years. Compared with never smoking, all-cause mortality RR was 1.08 (95%CI 1.01-1.17) for former smoking, 1.11 (95%CI 1.03-1.20) for current smoking, 1.09 (95%CI 0.99-1.20) for non-daily smoking, 1.06 (95%CI 0.96-1.16) for smoking < 10 cigarettes/day (median during follow-up 4 cigarettes/day), and 1.28 (95% CI 1.14-1.43) for smoking ≥ 10 cigarettes/day (median during follow-up 15 cigarettes/day). Mortality risk among daily smokers was greatest for COPD, lung cancer, cardiovascular diseases, and acute diabetic complications.

CONCLUSION

In this cohort of Mexican adults with diabetes, low-intensity daily smoking was associated with increased mortality, despite observing smoking patterns which are different from other populations, and over 5% of total deaths were associated with smoking.

Hepatic steatosis induced by nicotine plus Coca-Cola™ is prevented by nicotinamide riboside (NR)

Introduction

Cigarettes containing nicotine (Nic) are a risk factor for the development of cardiovascular and metabolic diseases. We reported that Nic delivered via injections or e-cigarette vapor led to hepatic steatosis in mice fed with a high-fat diet. High-fructose corn syrup (HFCS) is the main sweetener in sugar-sweetened beverages (SSBs) in the US. Increased consumption of SSBs with HFCS is associated with increased risks of non-alcoholic fatty liver disease (NAFLD). Nicotinamide riboside (NR) increases mitochondrial nicotinamide adenine dinucleotide (NAD+) and protects mice against hepatic steatosis. This study evaluated if Nic plus Coca-Cola™ (Coke) with HFCS can cause hepatic steatosis and that can be protected by NR.

Methods

C57BL/6J mice received twice daily intraperitoneal (IP) injections of Nic or saline and were given Coke (HFCS), or Coke with sugar, and NR supplementation for 10 weeks.

Results

Our results show that Nic+Coke caused increased caloric intake and induced hepatic steatosis, and the addition of NR prevented these changes. Western blot analysis showed lipogenesis markers were activated (increased cleavage of the sterol regulatory element-binding protein 1 [SREBP1c] and reduction of phospho-Acetyl-CoA Carboxylase [p-ACC]) in the Nic+Coke compared to the Sal+Water group. The hepatic detrimental effects of Nic+Coke were mediated by decreased NAD+ signaling, increased oxidative stress, and mitochondrial damage. NR reduced oxidative stress and prevented mitochondrial damage by restoring protein levels of Sirtuin1 (Sirt1) and peroxisome proliferator-activated receptor coactivator 1-alpha (PGC1) signaling.

Conclusion

We conclude that Nic+Coke has an additive effect on producing hepatic steatosis, and NR is protective. This study suggests concern for the development of NAFLD in subjects who consume nicotine and drink SSBs with HFCS.

Optimizing lifestyle profiles is potential for preventing nonalcoholic fatty liver disease and enhancing its survival

The aim of this study was to evaluate the association between lifestyle profile and disease incidence/mortality in patients with non-alcoholic fatty liver disease (NAFLD). Lifestyle profiles ascertainment was based on the latent profile analysis. The associations of lifestyle profile and outcomes were analyzed by multivariate logistic or Cox regressions. Four lifestyle profiles (profile 1 and 2 for male, profile 3 and 4 for female) were established for all participants. Compared to profile 1, profile 2 (P = 0.042) and profile 3 (P = 0.013) had lower incidence for NAFLD. In contrast, profile 4 showed similar NAFLD prevalence compared to profile 1 (P = 0.756). Individuals with NAFLD within profile 3 had the best long-term survival, and the HR was 0.55 (95% CI 0.40-0.76) for all-cause mortality (compared to profile 1). Profile 4 (P = 0.098) and profile 2 (P = 0.546) had similar all-cause survival compared to profile 1. We explored the associations of healthy lifestyle score with mortality and incidence of NAFLD stratified by lifestyle profiles. We observed that with the increase of healthy lifestyle score, participants within profile 2 did not display lower NAFLD incidence and better long-term survival in NAFLD cases. In this study, lifestyle profiles were constructed in NHANES participants. The distinct lifestyle profiles may help optimize decision-making regarding lifestyle management in preventing NAFLD development, as well as selection of a more personalized approach for improving NAFLD survival.

Association between the traditional Chinese medicine constitution and metabolic dysfunction-associated fatty liver disease in older people: A cross-sectional study

Background

Few studies have focused on the relationship between the traditional Chinese medicine constitution (TCMC) and metabolic dysfunction-associated fatty liver disease (MAFLD) in older populations. We sought to investigate the distribution of MAFLD and the TCMC in older people, and provide a theoretical basis for TCMC-based management of MAFLD in this population.

Methods

A cross-sectional study was conducted among older (≥65 years) individuals in Zhongshan, China. Information on common sociodemographic characteristics, medical history, anthropometric measurements, and the TCMC was collected. The chi-square test, multivariable logistic regression analysis, subgroup analysis, and inverse probability weighting of the propensity score were used to explore the relationship between MAFLD and the TCMC.

Results

Of 7085 participants, 1408 (19.9 %) had MAFLD. The three most common TCMC types in MAFLD patients were "phlegm-dampness", "gentleness", and "yin-deficiency". After adjustment for gender, age, tobacco smoking, alcohol consumption, body mass index, abnormal waist-to-hip ratio, hypertension, diabetes mellitus, and dyslipidemia, MAFLD was positively associated with the phlegm-dampness constitution (PDC) (ORadjusted (95 % CI) = 1.776 (1.496-2.108), P < 0.001), and negatively correlated with the qi-depression constitution (0.643 (0.481-0.860), 0.003). A stronger correlation between the PDC and MAFLD was observed in men compared with women (ORadjusted = 2.04 (95%CI = 1.47-2.84) vs. 1.70 (95%CI = 1.39-2.08), Pinteraction = 0.003) as well as between people who smoked tobacco and non-tobacco-smoking individuals (2.11 (1.39-3.21) vs. 1.75 (1.45-2.12), 0.006).

Conclusions

A positive relationship was observed between MAFLD and the PDC in older people living in Zhongshan. Early detection and treatment of the PDC (especially in men and smokers) could prevent the occurrence and development of MAFLD.

Metabolic dysfunction-associated steatotic liver disease and the heart

The prevalence and severity of metabolic dysfunction-associated steatotic liver disease (MASLD) are increasing. Physicians who treat patients with MASLD may acknowledge the strong coincidence with cardiometabolic disease, including atherosclerotic cardiovascular disease (asCVD). This raises questions on co-occurrence, causality, and the need for screening and multidisciplinary care for MASLD in patients with asCVD, and vice versa. Here, we review the interrelations of MASLD and heart disease and formulate answers to these matters. Epidemiological studies scoring proxies for atherosclerosis and actual cardiovascular events indicate increased atherosclerosis in patients with MASLD, yet no increased risk of asCVD mortality. MASLD and asCVD share common drivers: obesity, insulin resistance and type 2 diabetes mellitus (T2DM), smoking, hypertension, and sleep apnea syndrome. In addition, Mendelian randomization studies support that MASLD may cause atherosclerosis through mixed hyperlipidemia, while such evidence is lacking for liver-derived procoagulant factors. In the more advanced fibrotic stages, MASLD may contribute to heart failure with preserved ejection fraction by reduced filling of the right ventricle, which may induce fatigue upon exertion, often mentioned by patients with MASLD. Some evidence points to an association between MASLD and cardiac arrhythmias. Regarding treatment and given the strong co-occurrence of MASLD and asCVD, pharmacotherapy in development for advanced stages of MASLD would ideally also reduce cardiovascular events, as has been demonstrated for T2DM treatments. Given the common drivers, potential causal factors and especially given the increased rate of cardiovascular events, comprehensive cardiometabolic risk management is warranted in patients with MASLD, preferably in a multidisciplinary approach.

Hepatocyte CHRNA4 mediates the MASH-promotive effects of immune cell-produced acetylcholine and smoking exposure in mice and humans

Metabolic dysfunction-associated steatohepatitis (MASH) is a leading risk factor for liver cirrhosis and hepatocellular carcinoma. Here, we report that CHRNA4, a subunit of nicotinic acetylcholine receptors (nAChRs), is an accelerator of MASH progression. CHRNA4 also mediates the MASH-promotive effects induced by smoking. Chrna4 was expressed specifically in hepatocytes and exhibited increased levels in mice and patients with MASH. Elevated CHRNA4 levels were positively correlated with MASH severity. We further revealed that during MASH development, acetylcholine released from immune cells or nicotine derived from smoking functioned as an agonist to activate hepatocyte-intrinsic CHRNA4, inducing calcium influx and activation of inflammatory signaling. The communication between immune cells and hepatocytes via the acetylcholine-CHRNA4 axis led to the production of a variety of cytokines, eliciting inflammation in liver and promoting the pathogenesis of MASH. Genetic and pharmacological inhibition of CHRNA4 protected mice from diet-induced MASH. Targeting CHRNA4 might be a promising strategy for MASH therapeutics.

The Prevalence and Determinants of NAFLD and MAFLD and Their Severity in the VA Primary Care Setting

BACKGROUND & AIMS

A recent panel of international experts proposed the disease acronym metabolic (dysfunction)-associated fatty liver disease (MAFLD) in lieu of nonalcoholic fatty liver disease (NAFLD). We aimed to estimate the burden of and risk factors for NAFLD and MAFLD, and to examine the concordance between definitions in a Veterans population.

METHODS

We conducted a cross-sectional study among randomly selected patients within primary care at the Houston Veterans Affairs (VA) facility. Participants completed a survey, provided blood, and underwent Fibroscan. In the absence of heavy alcohol, hepatitis C virus and hepatitis B virus, a controlled attenuation parameter median ≥290 dB/m was used to define NAFLD, whereas MAFLD was defined as controlled attenuation parameter median ≥290 dB/m and either body mass index ≥25 kg/m2 or diabetes, or 2 or more of the following: hypertension, high triglycerides, low high-density lipoprotein cholesterol, and high low-density lipoprotein cholesterol.

RESULTS

The mean age of participants was 50.9 years, 55.4% were women, 42.8% were white, and 43.8% were Black. The prevalence of NAFLD was 40.6% (82/202). All 82 patients with NAFLD had a body mass index ≥25 kg/m2, and therefore met our criteria for MAFLD (ie, 100% concordance). Compared with patients with no metabolic trait, patients with ≥3 traits had a 48-fold (adjusted odds ratio, 47.6; 95% confidence interval, 11.3-200) higher risk of NAFLD/MAFLD. Overall, 19 participants (9.4% of the total, 15.9% of those with NAFLD) had at least moderate fibrosis.

CONCLUSIONS

NAFLD was present in 40% of Veterans registered in primary care; 9.4% of veterans had at least moderate hepatic fibrosis, with most having concurrent NAFLD. There was perfect concordance between NAFLD and the alternative MAFLD definition.

Risk Factors of Non-alcoholic Fatty Liver Disease in the Iranian Adult Population: A Systematic Review and Meta-analysis

Context: Non-alcoholic fatty liver disease (NAFLD) is progressing considerably worldwide. Identifying the risk factors of NAFLD is a critical step in preventing its progression. Methods: In November 2022, two independent researchers studied seven databases, including PubMed, ISI/WoS, ProQuest, Scopus, SID, Magiran, and Google Scholar, and reference list of relevant articles, searching studies that assessed NAFLD risk factors in the Iranian adult population. Heterogeneity between studies was assessed by Cochran’s test and its composition using I2 statistics. A random-effects model was used when heterogeneity was observed; otherwise, a fixed-effects model was applied. Egger’s regression test and Trim-and-Fill analysis were used to assess publication bias. Comprehensive Meta-analysis software (version 3) was used for the analyses of the present study. Results: The results of this study showed significant associations between NAFLD with age (n = 15, odds ratio (OR) = 2.12, 95% CI: 1.79 - 2.51), body mass index (n = 46, OR = 5.00, 95% CI: 3.34 - 7.49), waist circumference (n = 20, OR = 6.37, 95% CI: 3.25 - 12.48), waist-to-hip ratio (n = 17, OR = 4.72, 95% CI: 3.93 - 5.66), total cholesterol (n = 39, OR = 1.80, 95% CI: 1.52 - 2.13), high-density lipoprotein (n = 37, OR = 0.53, 95% CI: 0.44 - 0.65), low-density lipoprotein (n = 31, OR = 1.68, 95% CI: 1.38 - 2.05), triglyceride (n = 31, OR = 3.21, 95% CI: 2.67 - 3.87), alanine aminotransferase (n = 26, OR = 4.06, 95% CI: 2.94 - 5.62), aspartate aminotransferase (n = 27, OR = 2.16, 95% CI: 1.50 - 3.12), hypertension (n = 13, OR = 2.53, 95% CI: 2.32 - 2.77), systolic blood pressure (n = 13, OR = 1.83, 95% CI: 1.53 - 2.18), diastolic blood pressure (n = 14, OR = 1.80, 95% CI: 1.48 - 2.20), fasting blood sugar (n = 31, OR = 2.91, 95% CI: 2.11- 4.01), homeostatic model assessment for insulin resistance (n = 5, OR = 1.92, 95% CI: 1.48 - 2.59), diabetes mellitus (n = 15, OR = 3.04, 95% CI: 2.46 - 3.75), metabolic syndrome (n = 10, OR = 3.56, 95% CI: 2.79 - 4.55), and physical activity (n = 11, OR = 0.32, 95% CI: 0.24 - 0.43) (P < 0.05). Conclusions: In conclusion, several factors are significantly associated with NAFLD. However, anthropometric indices had the strongest relationship with NAFLD in the Iranian adult population.

Association between the dual use of electronic and conventional cigarettes and NAFLD status in Korean men

INTRODUCTION

This study investigated the association between smoking types, including dual use (usage of both combustible cigarettes and e-cigarettes), and non-alcoholic fatty liver disease (NAFLD) status in Korean men.

METHODS

Data from the 7th and 8th Korea National Health and Nutrition Examination Survey (KNHANES) 2016-2020 were used. The presence of NAFLD was defined by the respective cut-off values for the Hepatic Steatosis Index (HSI), NAFLD Ridge Score (NRS), and Korea National Health and Nutrition Examination Survey NAFLD score (KNS). Multivariate logistic regression analyses were used to determine the associations between smoking types and NAFLD as determined by HSI, NRS, and KNS.

RESULTS

After adjustment for confounders, an independent association was observed between dual use and NAFLD (HSI: AOR=1.47; 95% CI: 1.08-1.99, p=0.014; NRS: AOR=2.21; 95% CI: 1.70-2.86, p=0.000; KNS: AOR=1.35; 95% CI: 1.01-1.81, p=0.045). Cigarette only smokers also had significantly higher odds of NAFLD compared to never smokers for all of the NAFLD indices (HSI: AOR=1.22; 95% CI: 1.05-1.42, p=0.008; NRS: AOR=2.13; 95% CI: 1.87-2.42, p=0.000; KNS: AOR=1.33; 95% CI: 1.14-1.55, p=0.000). In subgroup analyses, no significant interaction effects were found for age, BMI, alcohol consumption, income, physical activity, and the diagnosis of T2DM. Moreover, cigarette only smokers and dual users differed significantly in terms of log-transformed urine cotinine and pack-years. The relationship between smoking type and pack-years was attenuated after stratification by age.

CONCLUSIONS

This study shows that the dual use of e-cigarettes and combustible cigarettes is associated with NAFLD. Age differences may explain why dual users, with a greater proportion of young people, appear to have fewer pack-years than cigarette only smokers. Further research should be conducted to investigate the adverse effects of dual use on hepatic steatosis.

Association between smoking and non-alcoholic fatty liver disease in Southeast Asia

An estimated 8 million people die each year from tobacco smoking, with an increasing frequency recently being observed in Southeast Asian countries, which is a preventable risk factor for mortality. NAFLD, fibrosis, advancement of hepatocellular carcinoma, and prognosis for those with severe liver disease are all negatively influenced. NAFLD and cigarette usage seem to be a direct link. Oxidative stress and oncogenic signals have been implicated in cancer development in animal models and human clinical trials. The elevated risk of cardiovascular disease and malignancies in those with steatohepatitis and those who have had liver transplants is exacerbated by smoking. We found that smoking cessation may increase treatment response and fibrosis regression rates, decrease hepatocellular carcinoma incidence, and improve liver transplant outcomes. In the last segment, we'll look at electronic cigarettes, a hot subject in public health right now, as well as additional repercussions of smoking.

Non-alcoholic fatty liver disease (NAFLD) and mental illness: Mechanisms linking mood, metabolism and medicines

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in the world and one of the leading indications for liver transplantation. It is one of the many manifestations of insulin resistance and metabolic syndrome as well as an independent risk factor for cardiovascular disease. There is growing evidence linking the incidence of NAFLD with psychiatric illnesses such as schizophrenia, bipolar disorder and depression mechanistically via genetic, metabolic, inflammatory and environmental factors including smoking and psychiatric medications. Indeed, patients prescribed antipsychotic medications, regardless of diagnosis, have higher incidence of NAFLD than population norms. The mechanistic pharmacology of antipsychotic-associated NAFLD is beginning to emerge. In this review, we aim to discuss the pathophysiology of NAFLD including its risk factors, insulin resistance and systemic inflammation as well as its intersection with psychiatric illnesses.

Gut bacteria alleviate smoking-related NASH by degrading gut nicotine

Tobacco smoking is positively correlated with non-alcoholic fatty liver disease (NAFLD)1-5, but the underlying mechanism for this association is unclear. Here we report that nicotine accumulates in the intestine during tobacco smoking and activates intestinal AMPKα. We identify the gut bacterium Bacteroides xylanisolvens as an effective nicotine degrader. Colonization of B. xylanisolvens reduces intestinal nicotine concentrations in nicotine-exposed mice, and it improves nicotine-exacerbated NAFLD progression. Mechanistically, AMPKα promotes the phosphorylation of sphingomyelin phosphodiesterase 3 (SMPD3), stabilizing the latter and therefore increasing intestinal ceramide formation, which contributes to NAFLD progression to non-alcoholic steatohepatitis (NASH). Our results establish a role for intestinal nicotine accumulation in NAFLD progression and reveal an endogenous bacterium in the human intestine with the ability to metabolize nicotine. These findings suggest a possible route to reduce tobacco smoking-exacerbated NAFLD progression.

The prevalence and incidence of NAFLD worldwide: a systematic review and meta-analysis

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide and the leading cause of liver-related morbidity and mortality. We aimed to predict the burden of NAFLD by examining and estimating the temporal trends of its worldwide prevalence and incidence.

METHODS

In this systematic review and meta-analysis, we searched MEDLINE, EMBASE, Scopus, and Web of Science without language restrictions for reports published between date of database inception and May 25, 2021. We included observational cross-sectional or longitudinal studies done in study populations representative of the general adult population, in whom NAFLD was diagnosed using an imaging method in the absence of excessive alcohol consumption and viral hepatitis. Studies were excluded if conducted in paediatric populations (aged <18 years) or subgroups of the general population. Summary estimates were extracted from included reports by KR and independently verified by HA using the population, intervention, comparison, and outcomes framework. Primary outcomes were the prevalence and incidence of NAFLD. A random-effects meta-analysis was used to calculate overall and sex-specific pooled effect estimates and 95% CIs.

FINDINGS

The search identified 28 557 records, of which 13 577 records were screened; 299 records were also identified via other methods. In total, 72 publications with a sample population of 1 030 160 individuals from 17 countries were included in the prevalence analysis, and 16 publications with a sample population of 381 765 individuals from five countries were included in the incidence analysis. The overall prevalence of NAFLD worldwide was estimated to be 32·4% (95% CI 29·9-34·9). Prevalence increased significantly over time, from 25·5% (20·1-31·0) in or before 2005 to 37·8% (32·4-43·3) in 2016 or later (p=0·013). Overall prevalence of NAFLD was significantly higher in men than in women (39·7% [36·6-42·8] vs 25·6% [22·3-28·8]; p<0·0001). The overall incidence of NAFLD was estimated to be 46·9 cases per 1000 person-years (36·4-57·5); 70·8 cases per 1000 person-years (48·7-92·8) in men and 29·6 cases per 1000 person-years (20·2-38·9) in women (p<0·0001). There was considerable heterogeneity between studies of both NAFLD prevalence (I²=99·9%) and NAFLD incidence (I²=99·9%).

INTERPRETATION

Worldwide prevalence of NAFLD is considerably higher than previously estimated and is continuing to increase at an alarming rate. Incidence and prevalence of NAFLD are significantly higher among men than among women. Greater awareness of NAFLD and the development of cost-effective risk stratification strategies are warranted to address the growing burden of NAFLD.

FUNDING

Canadian Institutes of Health.

Possible correlation between high circulatory levels of trimethylamine-N-oxide and 2177G>C polymorphisms of hepatic flavin containing monooxygenase 3 in Kurdish Population with non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a multifactorial disorder with complicated pathophysiology. Trimethylamine-N-oxide (TMAO) has been thought to be correlated with the pathogenesis of NAFLD. The single nucleotide polymorphisms (SNPs) of hepatic flavin-containing monooxygenase 3 (FMO3) regulate the concentration of TMAO. This case-control study investigated the plasma levels of TMAO as well as its possible correlation with the frequency of specific genotype of FMO3 (-2650C>G, -2543T>A, -2177G>C, -2589C>T, -2106G>A polymorphisms) in Kurdish patients with NAFLD. METHODS AND RESULTS: In 85 confirmed NAFLD patients and 30 healthy individuals, triglycerides (TG), total cholesterol (Chol), low-density lipoprotein (LDL), high-density lipoprotein (HDL), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) activities were measured. TMAO was also measured using the LC-MS/MS method. High-resolution melting analysis was applied to determine FMO3 genotypes. Plasma TMAO levels were significantly higher in patients (p = 0.030). A CC genotype with a frequency of 12.9% for SNP -2177G>C was found in Kurdish NAFLD patients. The distribution of the GC genotype was also significantly different (p = 0.017).

CONCLUSIONS

The current results provide documentation for high circulatory levels of TMAO and its possible correlation with the presence of the specific genotype -2177G>C FMO3 in Kurdish NAFLD patients.

Cigarette smoking and liver diseases

Cigarette smoking is a preventable risk factor for premature morbidity and mortality. A history of smoking is observed in approximately 40% of patients with liver disease, while a growing number of studies are investigating the potential impact of smoking in chronic liver diseases. This review discusses the effects of smoking on liver diseases, at multiple levels, with a focus on its potential causal role. Clinical evidence indicates that cigarette smoking negatively impacts the incidence and severity of fatty liver disease, fibrosis progression, hepatocellular carcinoma development, and the outcomes of patients with advanced liver disease. The underlying mechanisms are complex and involve different pathophysiological pathways including oxidative stress and oncogenic signals. Importantly, smoking promotes cardiovascular disease and extrahepatic cancers in patients with steatohepatitis and in transplant recipients. We discuss how promoting smoking cessation could improve the rates of treatment response (in clinical trials) and fibrosis regression, while reducing the risk of hepatocellular carcinoma and improving liver transplant outcomes. Finally, we discuss current challenges such as the referral of smokers to specialised units for smoking cessation.

Combined evaluation of Fibrosis-4 index and fatty liver for stratifying the risk for diabetes mellitus

Aims/Introduction

To investigate whether the Fibrosis‐4 index can help stratify the risk of diabetes mellitus in patients with fatty liver disease.

Materials and Methods

Based on fatty liver disease and Fibrosis‐4 index (cut‐off value 1.3), we retrospectively divided 9,449 individuals, who underwent at least two annual health checkups, into four groups stratified by sex: normal; high Fibrosis‐4 index without fatty liver disease; low Fibrosis‐4 index with fatty liver disease; and high Fibrosis‐4 index with fatty liver disease.

Results

Onset rates for diabetes mellitus in the normal, high Fibrosis‐4 index without fatty liver disease, low Fibrosis‐4 index with fatty liver disease and high Fibrosis‐4 index with fatty liver disease groups were 1.6%, 4.3%, 6.8% and 10.2%, respectively, in men, and 0.6%, 0.9%, 5.3% and 7.0%, respectively, in women. Compared with the normal group, the high Fibrosis‐4 index without fatty liver disease, low Fibrosis‐4 index with fatty liver disease and high Fibrosis‐4 index with fatty liver disease groups were at a significant risk for diabetes mellitus onset in both male and female participants. Furthermore, in both sexes, high Fibrosis‐4 index with fatty liver disease remained a significant risk factor on multivariate analysis (high fibrosis‐4 index with fatty liver disease group: adjusted hazard ratio 4.03, 95% confidence interval 2.19–7.42 [men] and adjusted hazard ratio 6.40, 95% confidence interval 1.77–23.14 [women]).

Conclusions

Individuals with fatty liver disease and high Fibrosis‐4 index had a higher risk of diabetes mellitus onset. Therefore, Fibrosis‐4 index can help stratify the risk of diabetes mellitus in patients with fatty liver disease and identify patients requiring intervention.

NAFLD in normal weight individuals

Nonalcoholic fatty liver disease (NAFLD) can develop in lean individuals. Despite a better metabolic profile, the risk of disease progression to hepatic inflammation, fibrosis, and decompensated cirrhosis in the lean is similar to that in obesity-related NAFLD and lean individuals may experience more severe hepatic consequences and higher mortality relative to those with a higher body mass index (BMI). In the absence of early symptoms and abnormal laboratory findings, lean individuals are not likely to be screened for NAFLD or related comorbidities; however, given the progressive nature of the disease and the increased risk of morbidity and mortality, a clearer understanding of the natural history of NAFLD in lean individuals, as well as efforts to raise awareness of the potential health risks of NAFLD in lean individuals, are warranted. In this review, we summarize available data on NAFLD prevalence, clinical characteristics, outcomes, and mortality in lean individuals and discuss factors that may contribute to the development of NAFLD in this population, including links between dietary and genetic factors, menopausal status, and ethnicity. We also highlight the need for greater representation of lean individuals in NAFLD-related clinical trials, as well as more studies to better characterize lean NAFLD, develop improved screening algorithms, and determine specific treatment strategies based on underlying etiology.

Fatty liver with metabolic disorder, such as metabolic dysfunction-associated fatty liver disease, indicates high risk for developing diabetes mellitus

Introduction

Nonalcoholic fatty liver disease (NAFLD) is diagnosed after excluding other liver diseases. The pathogenesis of NAFLD when complicated by other liver diseases has not been established completely. Metabolic dysfunction‐associated fatty liver disease (MAFLD) involves more metabolic factors than NAFLD, regardless of complications with other diseases. This study aimed to clarify the effects of fatty liver occurring with metabolic disorders, such as MAFLD without diabetes mellitus (DM), on the development of DM.

Materials and Methods

We retrospectively assessed 9,459 participants who underwent two or more annual health check‐ups. The participants were divided into the MAFLD group (fatty liver disease with overweight/obesity or non‐overweight/obesity complicated by metabolic disorders), simple fatty liver group (fatty liver disease other than MAFLD group), metabolic disorder group (metabolic disorder without fatty liver disease), and normal group (all other participants).

Results

The DM onset rates in the normal, simple fatty liver, metabolic disorder, and MAFLD groups were 0.51, 1.85, 2.52, and 7.36%, respectively. In the multivariate analysis, the MAFLD group showed a significantly higher risk of DM onset compared with other three groups (P < 0.01). Additionally, the risk of DM onset was significantly increased in fatty liver disease with overweight/obesity or pre‐diabetes (P < 0.01).

Conclusions

Fatty liver with metabolic disorders, such as MAFLD, can be used to identify patients with fatty liver disease who are at high risk of developing DM. Additionally, patients with fatty liver disease complicated with overweight/obesity or prediabetes are at an increased risk of DM onset and should receive more attention.

Associations Between Residential Exposure to Volatile Organic Compounds and Liver Injury Markers

Occupational exposures to volatile organic compounds (VOCs) have been associated with numerous health complications including steatohepatitis and liver cancer. However, the potential impact of environmental/residential VOC exposures on liver health and function is largely unknown. To address this knowledge gap, the objective of this cross-sectional study is to investigate associations between VOCs and liver injury biomarkers in community residents. Subjects were recruited from six Louisville neighborhoods, and informed consent was obtained. Exposure biomarkers included 16 creatinine-adjusted urinary metabolites corresponding to 12 parent VOCs. Serological disease biomarkers measured included cytokertain-18 (K18 M65 and M30), liver enzymes, and direct bilirubin. Associations between exposure and disease biomarkers were assessed using generalized linear models. Smoking status was confirmed through urinary cotinine levels. The population comprised of approximately 60% females and 40% males; White persons accounted 78% of the population; with more nonsmokers (n = 413) than smokers (n = 250). When compared with nonsmokers, males (45%) and Black persons (26%) were more likely to be smokers. In the overall population, metabolites of acrolein, acrylonitrile, acrylamide, 1,3-butadiene, crotonaldehyde, styrene, and xylene were positively associated with alkaline phosphatase. These associations persisted in smokers, with the exception of crotonaldehyde, and addition of N,N-dimethylformamide and propylene oxide metabolites. Although no positive associations were observed for K18 M30, the benzene metabolite was positively associated with bilirubin, irrespective of smoking status. Taken together, the results demonstrated that selected VOCs were positively associated with liver injury biomarkers. These findings will enable better risk assessment and identification of populations vulnerable to liver disease.

Ultra-processed food is associated with features of metabolic syndrome and non-alcoholic fatty liver disease

BACKGROUND & AIMS

High consumption of ultra-processed food (UPF) is associated with mortality and chronic morbidity but has not been studied concerning to non-alcoholic fatty liver disease (NAFLD). We aimed to test the association of UPF consumption with metabolic syndrome, NAFLD and related-liver damage.

METHODS

A cross-sectional study among volunteers who underwent abdominal ultrasound (AUS), anthropometrics, blood pressure measurements, and fasting blood tests including FibroMax for non-invasive assessment of NASH and significant fibrosis. A food-frequency questionnaire was used to evaluate UPF consumption using the NOVA classification.

RESULTS

A total of 789 subjects were included in the total sample (mean age 58.83 ± 6.58 years, 52.60% men), a reliable FibroMax test was obtained from 714 subjects, 305 subjects were diagnosed with NAFLD. High consumption of UPF was associated with higher odds for metabolic syndrome (OR = 1.88, 95% CI 1.31-2.71, P = .001) and its components; hypertension, hypertriglyceridemia, and low HDL, among the entire sample (OR = 1.53, 1.07-2.19, P = .026; OR = 1.51, 1.08-2.11, P = .017; OR = 1.55, 1.05-2.29, P = .028). In addition, it was associated with higher odds for NASH and hypertension (OR = 1.89, 1.07-3.38, P = .030; OR = 2.26, 1.20-4.26, P = .012 respectively) among subjects with NAFLD. Stratification by smoking status revealed an association between high UPF consumption and significant fibrosis among ever smokers in the entire sample and among subjects with NAFLD (OR = 1.89, 95% CI 1.03-3.45, P = .039; OR = 2.85, 1.14-7.14, P = .026 respectively).

CONCLUSIONS

High UPF consumption is associated with metabolic syndrome in the general population, and among those with NAFLD it is associated with NASH marker. Ever-smoking may act synergistically with UPF to amplify the risk for fibrosis.

Non-alcoholic fatty liver disease: A patient guideline

This patient guideline is intended for all patients at risk of or living with non-alcoholic fatty liver disease (NAFLD). NAFLD is the most frequent chronic liver disease worldwide and comes with a high disease burden. Yet, there is a lot of unawareness. Furthermore, many aspects of the disease are still to be unravelled, which has an important impact on the information that is given (or not) to patients. Its management requires a close interaction between patients and their many healthcare providers. It is important for patients to develop a full understanding of NAFLD in order to enable them to take an active role in their disease management. This guide summarises the current knowledge relevant to NAFLD and its management. It has been developed by patients, patient representatives, clinicians and scientists and is based on current scientific recommendations, intended to support patients in making informed decisions.

Nonalcoholic fatty liver disease is a risk factor for glucose intolerance onset in men regardless of alanine aminotransferase status

INTRODUCTION

Fatty liver disease (FLD) is a surrogate condition for glucose intolerance development. FLD may involve normal or abnormal liver enzyme levels. Whether FLD is a risk factor for glucose intolerance, regardless of liver enzyme levels, remains unknown. We assessed relationships between the development of impaired fasting glucose (IFG) and FLD, liver enzyme abnormalities, and alcohol consumption.

MATERIALS AND METHODS

We retrospectively evaluated 8,664 participants with more than two annual health check-ups. Participants were classified according to sex, alcohol consumption, alanine aminotransferase (ALT) levels, and fatty liver status.

RESULTS

In univariate analyses, IFG onset among men was related to normal or high ALT levels with FLD in the nonalcoholic and alcoholic groups (P-trend < 0.01). In multivariate analyses, IFG onset among nonalcoholic men was associated with normal or high ALT levels with FLD, independent of potential confounding factors (P-trend < 0.01). However, IFG onset was non-independently associated with any condition among alcoholic men. In univariate analyses, IFG onset among women was related to normal or high ALT levels with FLD in the nonalcoholic group (P-trend < 0.01) and high ALT levels with FLD in the alcoholic group (P-trend < 0.05). In multivariate analyses, IFG onset was independently associated with only normal ALT levels in nonalcoholic FLD women.

CONCLUSIONS

Among nonalcoholic men and women, FLD was a risk factor for IFG onset, including normal ALT concentrations. Care is needed for individuals with nonalcoholic FLD, regardless of liver injury, possibly helping reduce glucose intolerance risk.

Dietary Treatment for NAFLD: New Clinical and Epidemiological Evidence and Updated Recommendations

The key factor in preventing and treating nonalcoholic fatty liver disease (NAFLD) is a holistic lifestyle modification approach, encompassing diet based on healthy eating patterns of unprocessed foods, exercise, balanced drinking, and smoking habits. The Mediterranean diet and other healthy dietary patterns can reduce liver fat and may be related with lower disease progression. The type of diet should be tailored to the patient's cultural and personal preferences. Changing dietary composition without reducing caloric intake may offer an additional and sometimes more feasible alternative, so that the nutritional treatment incorporates, but is not focused on, weight reduction goals. The growing global consumption of ultra-processed foods, which is the polar opposite of the Mediterranean diet and its concept of home-based cooking, poses a great challenge in the prevention of NAFLD and probably hepatocellular carcinoma.This review will cover the most updated clinical and epidemiological evidence for lifestyle treatment in NAFLD and provide practical treatment tools.

Non-Alcoholic Fatty Liver Disease Is Strongly Associated with Smoking Status and Is Improved by Smoking Cessation in Japanese Males: A Retrospective Study

BACKGROUND

Cigarette smoking is known to be a significant risk factor associated with non-alcoholic fatty liver disease (NAFLD). We aimed to examine the association between smoking status and the severity of fatty liver with regard to sex and smoking cessation.

METHODS

In total, 13,466 subjects (6,642 males and 6,824 females) who had undergone abdominal ultrasonography for health check-up, multivariable logistic regression analysis was retrospectively conducted to assess the association between smoking status and the prevalence of NAFLD stratified by sex after adjusting for other potential confounders.

RESULTS

Male sex (odds ratio [OR] 3.27, 95% confidence interval [CI] 3.00-3.57) and smoking history (former smoker: OR 1.23, 95% CI 1.10-1.38, current smoker: OR 1.31, 95% CI 1.17-1.47) were significantly associated with NAFLD. In males with a smoking history, an increased pack-year was strongly associated with the prevalence and severity of NAFLD (prevalence of moderate to severe fatty liver: Pack-year from 0.01 to 9.99, 21.3%; Pack-year from 10.00 to 19.99, 27.2%; Pack-year ≥20.00, 33.7%; P<0.0001), although the prevalence of moderate to severe fatty liver was inversely associated with the duration of smoking cessation (more than 10 years vs. within 5 years, OR 0.71, 95% CI 0.53-0.96). In female subjects, light current smoking was negatively associated with NAFLD (current smoker with a pack-year from 0.01 to 9.99 vs. never smoker, OR 0.41, 95% CI 0.19-0.76).

CONCLUSIONS

Smoking status and pack-year were strongly associated with the prevalence and severity of NAFLD, especially in Japanese males. However, smoking cessation improved NAFLD in this population.

Validation of a Non-Laboratory Based Screening Tool for Predicting Non-Alcoholic Fatty Liver Disease in an Egyptian Setting

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a common chronic liver disorder in more than 20% of the general population worldwide.  Several combinations of non-invasive factors and scoring models were investigated as indicators of NAFLD. This study aimed to validate and adapt an established fatty liver score, which allows the identification of NAFLD based on routinely available clinical and laboratory data.

MATERIALS AND METHODS

The study cohort comprised 190 adults seeking health check-up at the out-patient clinic of a tertiary care hospital in Alexandria, Egypt. Anthropometric, clinical, and laboratory data were recorded and the status of fatty liver was diagnosed by abdominal ultrasound. A logistic regression model was built to determine the predictors of NAFLD. The performance of the derived risk scores was compared to other existing models.

RESULTS

Obesity (60.0%), metabolic syndrome (42.6%), and NAFLD (56.8%) were predominant features among the study population. Smoking [OR (95% CI) = 4.4 (0.9-21.4)], obesity [OR (95% CI) = 4.0 (1.7-9.7)], hypertension [OR (95% CI) = 2.4 (1.03-5.5)], elevated serum total cholesterol [OR (95% CI) = 4.8 (1.8-13.1)], triglycerides [OR (95% CI) = 11.8 (2.3-661.02)], and ALT [OR (95% CI) = 4.8 (1.8-13.1)] were multivariate predictors of NAFLD. A NAFLD screening questionnaire with values applicable for Egyptians was adapted from an existing model after validation. A total score ≥7 was suggestive of NAFLD [AUC = 0.810 (0.749-0.871); sensitivity = 87.0%; specificity = 62.2%; PPV = 75.2%; NPV = 78.5%].

CONCLUSIONS

NAFLD can be sufficiently predicted among apparently healthy Egyptians by a tempted simple and non-invasive scoring index although external validation is warranted.

Nonalcoholic fatty liver disease and cardiovascular disease phenotypes

Nonalcoholic fatty liver disease is increasingly recognized as a major global health problem. Intertwined with diabetes, metabolic syndrome, and obesity, nonalcoholic fatty liver disease embraces a spectrum of liver conditions spanning from steatosis to inflammation, fibrosis, and liver failure. Compared with the general population, the prevalence of cardiovascular disease is higher among nonalcoholic fatty liver disease patients, in whom comprehensive cardiovascular risk assessment is highly desirable. Preclinical effects of nonalcoholic fatty liver disease on the heart include both metabolic and structural changes eventually preceding overt myocardial dysfunction. Particularly, nonalcoholic fatty liver disease is associated with enhanced atherosclerosis, heart muscle disease, valvular heart disease, and arrhythmias, with endothelial dysfunction, inflammation, metabolic dysregulation, and oxidative stress playing in the background. In this topical review, we aimed to summarize current evidence on the epidemiology of nonalcoholic fatty liver disease, discuss the pathophysiological links between nonalcoholic fatty liver disease and cardiovascular disease, illustrate nonalcoholic fatty liver disease-related cardiovascular phenotypes, and finally provide a glimpse on the relationship between nonalcoholic fatty liver disease and cardiac steatosis, mitochondrial (dys)function, and cardiovascular autonomic dysfunction.

Regional difference in the susceptibility of non-alcoholic fatty liver disease in China

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is a global health problem with high geographic heterogeneity. We aimed to investigate regional-specific concomitant rate of NAFLD and quantitative relationship between liver fat content (LFC) and glucose metabolism parameters in representative clinical populations from six provinces/municipalities of China.

RESEARCH DESIGN AND METHODS

A total of 2420 eligible Han Chinese were enrolled consecutively from 10 clinics of obesity, diabetes and metabolic diseases located at six provinces/municipalities of China, and divided into North (Tianjin, Shandong and Heilongjiang) and South (Shanghai, Jiangsu and Henan) groups according to their geographical latitude and proximity of NAFLD concomitant rate. LFC was assessed by a quantitative ultrasound method. Multivariate regression models and analysis of covariance were used to assess the regional difference in the risk of NAFLD.

RESULTS

The concomitant rate of NAFLD was 23.3%, 44.0% and 55.3% in individuals with normal glucose tolerance (NGT), pre-diabetes and diabetes, respectively. A higher concomitant rate of NAFLD was found in the participants from the North comparing with the South group, regardless of glucose metabolism status (34.7% vs 16.2% in NGT, 61.5% vs 34.7% in pre-diabetes and 67.1% vs 48.1% in diabetes). This regional difference remained significant after adjustment for age, gender, alcohol drinking, cigarette smoking, confounding metabolic parameters and liver enzymes. For any given blood glucose, participants from the North had higher LFC than those from the South group.

CONCLUSIONS

Half of Han Chinese with pre-diabetes/type 2 diabetes had NAFLD, and the individuals from the North cities were more susceptible to NAFLD.

Secondhand Smoke Induces Liver Steatosis through Deregulation of Genes Involved in Hepatic Lipid Metabolism

We investigated the role of secondhand smoke (SHS) exposure, independently of diet, in the development of chronic liver disease. Standard diet-fed mice were exposed to SHS (5 h/day, 5 days/week for 4 months). Genome-wide gene expression analysis, together with molecular pathways and gene network analyses, and histological examination for lipid accumulation, inflammation, fibrosis, and glycogen deposition were performed on the liver of SHS-exposed mice and controls, upon termination of exposure and after one-month recovery in clean air. Aberrantly expressed transcripts were found in the liver of SHS-exposed mice both pre- and post-recovery in clean air (n = 473 vs. 222). The persistent deregulated transcripts (n = 210) predominantly affected genes and functional networks involved in lipid metabolism as well as in the regulation of the endoplasmic reticulum where manufacturing of lipids occurs. Significant hepatic fat accumulation (steatosis) was observed in the SHS-exposed mice, which progressively increased as the animals underwent recovery in clean air. Moderate increases in lobular inflammation infiltrates and collagen deposition as well as loss of glycogen were also detectable in the liver of SHS-exposed mice. A more pronounced phenotype, manifested as a disrupted cord-like architecture with foci of necrosis, apoptosis, inflammation, and macrovesicular steatosis, was observed in the liver of SHS-exposed mice post-recovery. The progressive accumulation of hepatic fat and other adverse histological changes in the SHS-exposed mice are highly consistent with the perturbation of key lipid genes and associated pathways in the corresponding animals. Our data support a role for SHS in the genesis and progression of metabolic liver disease through deregulation of genes and molecular pathways and functional networks involved in lipid homeostasis.

Effect of weight change and lifestyle modifications on the development or remission of nonalcoholic fatty liver disease: sex-specific analysis

The effects of changes in various lifestyle habits on nonalcoholic fatty liver disease (NAFLD) have not been well elucidated. We aimed to clarify how weight change and lifestyle modifications were associated with the development or remission of NAFLD. In this longitudinal cohort study, we reviewed the periodic health checkup data of 1,421 subjects with no causes of liver disease besides NAFLD who had received at least two health checkups between 2009 and 2018. The prevalence of NAFLD at baseline was 34.1% (484/1,421). During follow-up period (4.6 ± 2.8 years), 104 subjects developed NAFLD and 127 subjects demonstrated NAFLD remission. The frequency of NAFLD development or that of NAFLD remission significantly increased as the larger weight gain or weight loss was, respectively (both, p < 0.001). Approximately 40% of the subjects who maintained ≥ 1%/year weight loss achieved NAFLD remission. By multivariate analysis, quitting smoking were independently associated with NAFLD development (adjusted odds ratio [AOR], 2.86; 95% CI, 1.24–6.62). Subjects who quit smoking demonstrated large weight gain (≥1%/year) significantly more frequently than the other subjects (p < 0.001). In sex-specific analysis, starting to exercise was independently associated with NAFLD remission in men (AOR, 2.38; 95% CI, 1.25–4.53).

Cigarette smoking differentially regulates inflammatory responses in a mouse model of nonalcoholic steatohepatitis depending on exposure time point

Cigarette smoke (CS) is a risk factor for the development of nonalcoholic fatty liver disease. However, the role of mainstream CS (MSCS) in the pathogenesis of nonalcoholic steatohepatitis (NASH) remains unclear. During the first (early exposure) or last (late exposure) three weeks of methionine-choline deficient with high fat diet feeding (6 weeks), each diet group was exposed to MSCS (300 or 600 μg/L). Hepatic or serum biochemical analysis showed that MSCS differentially modulated hepatic injury in NASH milieu, depending on exposure time points. Consistently, NASH-related hepatocellular apoptosis and fibrosis were increased in the early exposure group, but decreased in the late exposure group, except for steatosis. Ex vivo experiments showed that CS extract differentially regulated inflammatory responses in co-cultured hepatocytes and macrophages isolated from steatohepatitic livers after 10 days or 3 weeks of diet feeding. Furthermore, CS differentially up- and down-regulated the expression levels of M1/M2 polarization markers and peroxisome proliferator-activated receptor-gamma (PPARγ) in livers (29% and 38%, respectively) or co-cultured macrophages (2 and 2.5 fold, respectively). Collectively, our findings indicate that opposite effects of MSCS on NASH progression are mediated by differential modulation of PPARγ and its-associated M1/M2 polarization in hepatic macrophages, depending on exposure time points.

Extra-hepatic manifestations and complications of nonalcoholic fatty liver disease

This review article aims to synthesize the evidence regarding nonalcoholic fatty liver disease (NAFLD) as a systemic disorder. We critically discuss the metabolic syndrome and its components; the cardiovascular and the endocrine system; chronic respiratory disorders; the musculoskeletal system; the skin; and extra-hepatic tumors. We conclude that, while some of these extra-hepatic conditions clearly predispose to the development of secondary forms of NAFLD (typically hypothyroidism-induced NAFLD), others result from pre-existent NAFLD (e.g., certain extra-hepatic tumors) and others (such as Type 2 Diabetes) have, with NAFLD, mutual and bidirectional associations. Analyzed data imply that NAFLD is not merely a hepatic disease. It is also and possibly more importantly, a systemic disorder requiring a special awareness, a multidisciplinary approach and a multidimensional vision.

Smoking and Nonalcoholic Fatty Liver Disease

Background & Aims

Nonalcoholic fatty liver disease (NAFLD) has become the most common liver disease in Western countries. Smoking and diabetes mellitus (DM) have been shown to increase mortality; however, whether NAFLD adds to the detrimental effect of smoking in DM and non‐DM patients is unknown. We evaluated the possible interactive effect of NAFLD and smoking on mortality risk in a US population‐based sample.

Methods

Cross‐sectional data from 11 205 participants in the third National Health and Nutrition Examination Survey were analysed. NAFLD was defined as ultrasonographic hepatic steatosis without evidence of other liver diseases. Proportional hazards regression modelling was used to test for the multiplicative interaction of NAFLD and smoking on overall mortality, controlling for DM.

Results

36.5% of the participants had NAFLD of whom 21.1% were current smokers, while among non‐NAFLD subjects, 26.2% reported current smoking. Smoking was associated with a hazard ratio (HR) of 2.23 (95% confidence interval (CI): 1.87‐2.65) among non‐NAFLD subjects, and 2.31 (95% CI: 1.33‐2.92, P < 0.01) among NAFLD patients. In contrast, the HR for NAFLD was 1.01 (95% CI: 0.78‐1.31, P = 0.96) among smokers and 0.98 (95% CI: 0.87‐1.10, P = 0.73) among non‐smokers. There was no evidence of interaction between NAFLD and smoking (HR = 1.01, 95% CI: 0.74‐1.38, P = 0.94) in the combined model.

Conclusion

We found that smoking increased mortality by two‐fold among the US population. Although the magnitude of the increase in mortality did not differ from that in non‐NAFLD subjects, smoking represents a modifiable determinant of long‐term outcomes in NAFLD patients.

Smoking results in accumulation of ectopic fat in the liver

OBJECTIVE

An association between smoking and nonalcoholic fatty liver disease has been reported. However, objective quantification of intrahepatic fat via magnetic resonance spectroscopy (MRS) in relation to smoking has rarely been performed in previous studies. Moreover, the possible pathways via which smoking could induce ectopic fat accumulation have not yet been addressed. The current study aimed to examine the association between smoking status and intrahepatic fat quantity and explore the possible mediating effects of triglycerides (TG) and adiponectin.

SUBJECTS AND METHODS

Magnetic resonance imager (MRI) spectra were analyzed to quantify intrahepatic fat in 45 men who were on average 62.3 years of age. Smoking status and alcohol intake were self-reported. Accelerometers were used to record daily total physical activity. Fasting blood TG and adiponectin levels were measured enzymatically. Differences in mean intrahepatic fat values according to smoking status were assessed using analysis of covariance.

RESULTS

A stepwise increase in mean intrahepatic fat was observed between never, former, and current smokers, respectively, independent of age, physical activity, alcohol intake, and body mass index (BMI) (P=0.005). Adjustment for TG and adiponectin significantly attenuated this association (P=0.074).

CONCLUSION

Current smoking was significantly associated with increased intrahepatic fat, which may be a result of adipocyte dysfunction, manifested as high circulating TG concentrations and low adiponectin levels.