Synergistic effect of fatty liver and smoking on metabolic syndrome

The relationship between smoking cessation history and significant liver fibrosis among the population with metabolic dysfunction-associated steatotic liver disease in the United States

BACKGROUND

Smoking was identified as a risk factor for the development of liver fibrosis in patients with metabolic dysfunction-associated steatotic liver disease (MASLD). However, the association between smoking cessation history and the development of liver fibrosis remains unclear. This study was intended to analyze the association between smoking cessation history and significant liver fibrosis in adult MASLD participants in the United States.

METHODS

This study utilized data from 2643 patients with MASLD from the National Health and Nutrition Examination Survey (NHANES). Significant liver fibrosis was detected based on transient elastography measurements. According to the smoking questionnaire data, patients were categorized as non-smokers, ex-smokers and current smokers. A multivariate logistic regression analysis, adjusted for weights, was performed to investigate the relationship between smoking cessation history and the presence of significant liver fibrosis in participants with MASLD.

RESULTS

A total of 2643 patients with MASLD were included in this study. Compared with non-smokers, ex-smokers had a slightly elevated risk of developing significant liver fibrosis (OR: 1.07, 95% CI: 1.02-1.13). Specifically, a positive correlation was observed between patients who quit smoking for < 20 years and significant liver fibrosis (OR: 1.07, 95% CI: 1.01-1.15). Furthermore, MASLD patients who started regularly smoking at an age of ≤ 20 years (OR: 1.09, 95% CI: 1.02-1.16) and had a smoking duration of ≥ 10 years before quitting (OR: 1.10, 95% CI: 1.02-1.18) were also highly correlated with an increased likelihood of developing significant liver fibrosis.

CONCLUSIONS

This study revealed that individuals with MASLD who have ceased smoking exhibit an elevated risk for significant liver fibrosis when compared to those who never smoked. It is highly emphasized that MASLD patients who quit smoking for < 20 years, started regularly smoking at an age of ≤ 20 years, and had a smoking duration of ≥ 10 years before quitting should be extremely vigilant regarding the risk of significant liver fibrosis.

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.

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.

Non-Alcoholic Fatty Liver Disease Modifies Serum Gamma-Glutamyl Transferase in Cigarette Smokers

Background

Serum gamma-glutamyl transferase (GGT) is a marker of oxidative stress, associated with increased cardiovascular (CV) risk. The impact of smoking on oxidative stress may be aggravated in individuals with non-alcoholic fatty liver disease (NAFLD). We aimed to ascertain the association of smoking on GGT levels in the presence or absence of NAFLD.

Methods

We evaluated 6,354 healthy subjects (43 ± 10 years, 79% males) without clinical cardiovascular disease (CVD) undergoing an employer-sponsored physical between December 2008 and December 2010. NAFLD was diagnosed by ultrasound and participants were categorized as current or non-smokers by self report. A multivariate linear regression of the cross-sectional association between smoking and GGT was conducted based on NAFLD status.

Results

The prevalence of NAFLD was 36% (n = 2,299) and 564 (9%) were current smokers. Smokers had significantly higher GGT levels in the presence of NAFLD (P < 0.001). After multivariable adjustment, current smoking was associated with 4.65 IU/L higher GGT level, P < 0.001, compared to non-smokers. When stratified by NAFLD, the magnitude of this association was higher in subjects with NAFLD (β-coefficient: 11.12; 95% confidence interval (CI): 5.76 - 16.48; P < 0.001); however, no such relationship was observed in those without NAFLD (β: -0.02; 95% CI: -3.59, 3.56; P = 0.992). Overall the interaction of NAFLD and smoking with GGT levels as markers of oxidative stress was statistically significant.

Conclusions

Smoking is independently associated with significantly increased oxidative stress as measured by GGT level. This association demonstrates effect modification by NAFLD status, suggesting that smoking may intensify CV risk in individuals with NAFLD.

Impact of non-alcoholic fatty liver disease and smoking on colorectal polyps

OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) and smoking have similar mechanisms of promoting colorectal polyps. The potential link between NAFLD and smoking in men and colorectal polyps has not been adequately evaluated. The aim is to investigate this association.

METHODS

A retrospective cross-sectional study was conducted on 2409 individuals undergoing a health check. Univariate and multivariate logistic regression were performed for analyzing the association between risk factors and colorectal polyps. Individuals were divided into four groups: Q1: NAFLD (-)/smoking (-); Q2: NAFLD (+)/smoking (-); Q3: NAFLD (-)/smoking (+); Q4: NAFLD (+)/smoking (+). Logistic analyses were used to explore associations for the whole study population and stratified groups.

RESULTS

The prevalence of colorectal polyps was 38.8% in males, and that of colorectal polyps in smokers and individuals with NAFLD were 47.0% (428/911) and 42.9% (267/622), respectively. With Q1 as reference, subjects with NAFLD (+) and smoking habits (+) had the highest ORs for colorectal polyps (OR = 2.64, 95% CI: 1.91 - 3.64, P < 0.001), adenomatous polyps (OR = 2.06, 95% CI: 1.38 - 3.05, P < 0.05), non-adenomatous polyps (OR = 1.97, 95% CI: 1.39 - 2.80, P < 0.05), ≥ 3 polyps (OR = 2.05, 95% CI: 1.31 - 3.22, P < 0.05) and proximal polyps (OR = 1.58, 95% CI: 1.02 - 2.45, P < 0.05) after adjusting for confounding variables.

CONCLUSIONS

Men with NAFLD and smoking habits have an increasing risk of colorectal polyps.

Sperm microRNA Content Is Altered in a Mouse Model of Male Obesity, but the Same Suite of microRNAs Are Not Altered in Offspring's Sperm

The prevalence of obesity is increasing worldwide and has tripled in men of reproductive age since the 1970s. Concerningly, obesity is not only comorbid with other chronic diseases, but there is mounting evidence that it increases the non-communicable disease load in their children (eg mortality, obesity, autism). Animal studies have demonstrated that paternal obesity increases the risk of metabolic (eg glucose metabolism defects, obesity) and reproductive disorders in offspring. Epigenetic changes within sperm are clear mechanistic candidates that are associated with both changes to the father’s environment and offspring phenotype. Specifically there is emerging evidence that a father’s sperm microRNA content both responds to paternal environmental cues and alters the gene expression profile and subsequent development of the early embryo. We used a mouse model of high fat diet (HFD) induced obesity to investigate whether male obesity could modulate sperm microRNA content. We also investigated whether this alteration to a father’s sperm microRNA content lead to a similar change in the sperm of male offspring. Our investigations were initially guided by a Taqman PCR array, which indicated the differential abundance of 28 sperm borne microRNAs in HFD mice. qPCR confirmation in a much larger cohort of founder males demonstrated that 13 of these microRNAs were differentially abundant (11 up-regulated; 2 down-regulated) due to HFD feeding. Despite metabolic and reproductive phenotypes also being observed in grand-offspring fathered via the male offspring lineage, there was no evidence that any of the 13 microRNAs were also dysregulated in male offspring sperm. This was presumably due to the variation seen within both groups of offspring and suggests other mechanisms might act between offspring and grand-offspring. Thus 13 sperm borne microRNAs are modulated by a father’s HFD and the presumed transfer of this altered microRNA payload to the embryo at fertilisation potentially acts to alter the embryonic molecular makeup post-fertilisation, altering its growth trajectory, ultimately affecting adult offspring phenotype and may contribute to paternal programming.

Nonalcoholic Fatty liver disease and risk of diabetes and cardiovascular disease: what is important for primary care physicians?

Nonalcoholic fatty liver disease (NAFLD) is emerging as the most common chronic liver condition in Western World and across the globe. NAFLD prevalence is estimated to be around one-third of the total population. There are no published data that project the future prevalence of NAFLD, but with an increase in epidemic of diabetes and obesity, it is possible to suggest an increase in a number of individuals with NAFLD. NAFLD is associated with insulin resistance and occurs with an increase in cluster of features of metabolic syndrome and type 2 diabetes. Therefore, it is important to exclude the possibility of diabetes in those individuals with evidence of fatty liver. The global diabetes epidemic continues to grow, and it is estimated that the number of people with diabetes will double by year 2030. NAFLD is also a risk factor for an increase in cardiovascular incidence independent of age, sex, low-density lipoprotein-cholesterol, smoking, and cluster of metabolic syndromes. It is expected that NAFLD will be an important challenge for health providers in the near future. Taking all these factors into consideration, we believe that increasing awareness of metabolic and cardiovascular impact of NAFLD among general practitioners and health authorities may decrease the serious consequences of late diagnosis of NAFLD. Importantly, the collaboration between medical specialties is vital in decreasing the impact of the epidemic of NAFLD. The focus of this review is in the role of primary care physician in diagnosis, treatment and prevention of NAFLD and patients education.

Interactive effects of smoking and glutathione S-transferase polymorphisms on the development of non-alcoholic fatty liver disease

Glutathione S-transferases (GSTs) protect cells against exogenous and endogenous oxidative stress. GST polymorphisms are associated with the development of cardiovascular disease (CVD) and diabetes mellitus (DM), especially in current-smokers. Non-alcoholic fatty liver disease (NAFLD) is a predictor of future CVD or DM, because oxidative stress contributes to their pathogenesis. This study investigated whether the combination of smoking status and GST genotypes could affect the risk for NAFLD. A cross-sectional analysis was conducted among 713 Japanese participants (458 males and 255 females) during a health screening program. The GSTM1 null, GSTT1 null, GSTP1 A/B or B/B and GSTA1 A/B or B/B genotypes were determined and deemed to be high-risk genotypes. The prevalence of NAFLD was 18.7%. Among never-smokers, carriers of one, and those of two or more high-risk GSTM1, GSTP1 or GSTA1 genotypes were at a higher risk for NAFLD than those who were not carriers [odds ratio (95% confidence interval): 2.6 (1.1-5.9) and 3.3 (1.3-8.1), respectively], and the risk was further increased among current-smokers [4.6 (1.6-13.0) and 5.4 (1.2-23.7), respectively]. This is the first report to show that the combination of current-smoking and harboring high-risk GSTM1, GSTP1 and/or GSTA1 genotypes is interactively associated with the risk of NAFLD.

Fatty liver score and 15-year incidence of type 2 diabetes

PURPOSE

Both non-alcoholic fatty liver (NAFL) and alcoholic fatty liver (AFL) are strongly associated with obesity, metabolic syndrome, and type 2 diabetes mellitus (T2DM). Recently, also the vitamin D level has been associated with these and may also be associated with fatty liver (FL). Liver function tests (LFTs) are insensitive markers of FL, but use of scores may help in identifying subjects with FL. We studied how LFTs and the FL score predict the development of T2DM in subjects with AFL versus NAFL and low versus high vitamin D levels.

METHODS

A cohort study based on 4,517 participants, aged 40-79, from the representative Mini-Finland Health Survey was carried out. During a follow-up of 15 years, 217 T2DM cases occurred. LFTs were determined from serum samples, and the FL score was formed using BMI, fasting glucose, HDL cholesterol, and GGT concentrations.

RESULTS

The risk of T2DM incidence in the highest versus lowest quartile was twofold for the LFTs and ninefold for the FL score. A total of 77 % (95 % confidence interval: 57-87 %) of the T2DM cases could have been prevented if all individuals' FL scores had been at the level of the first quartile. Heavy alcohol consumption and low serum vitamin D concentrations were associated with an increased risk of T2DM among individuals with high FL scores.

CONCLUSIONS

The FL score is a useful tool for diagnosing FL in epidemiological studies. A high FL score predicts increased risk of T2DM, especially when combined with heavy alcohol consumption or low vitamin D levels.

The endocrine effects of nicotine and cigarette smoke

With a current prevalence of approximately 20%, smoking continues to impact negatively upon health. Tobacco or nicotine use influences the endocrine system, with important clinical implications. In this review we critically evaluate the literature concerning the impact of nicotine as well as tobacco use on several parameters of the endocrine system and on glucose and lipid homeostasis. Emphasis is on the effect of smoking on diabetes mellitus and obesity and the consequences of smoking cessation on these disorders. Understanding the effects of nicotine and cigarettes on the endocrine system and how these changes contribute to the pathogenesis of various endocrine diseases will allow for targeted therapies and more effective approaches for smoking cessation.

Smoking, habitual tea drinking and metabolic syndrome in elderly men living in rural community: the Tianliao old people (TOP) study 02

The literature shows an inconsistent relationship between lifestyle behaviors and metabolic syndrome (MetS), especially in the elderly. We designed this study to investigate the interrelationships among cigarette smoking, tea drinking and MetS, and to verify the factors associated with MetS in elderly males dwelling in rural community. In July 2010, with a whole community sampling method, 414 male subjects aged over 65 dwelling in Tianliao township were randomly sampled. The response rate was 60.8%. Each subject completed the structured questionnaires including sociodemographic characteristics, habitual behaviors (including cigarette smoking and tea drinking habits) and medical history. After an overnight fast, the laboratory and anthropometric data were obtained. MetS was confirmed according to the criteria defined by the modified NCEP ATP III for the male Chinese population. Subjects were split into either non-MetS or MetS groups for further analysis. Of the 361 subjects with complete data, 132 (36.6%) elderly men were classified as having MetS. Using binary logistic regression, body mass index, serum uric acid, high sensitivity C-reactive protein, HOMA index, current smokers (OR = 2.72, 95%CI: 1.03 ∼ 7.19), total smoking amount > = 30 (OR = 2.78, 95%CI: 1.31 ∼ 5.90) and more than 20 cigarettes daily (OR = 2.54, 95%CI: 1.24 ∼ 5.18) were positively associated with MetS. Current un- or partial fermented tea drinker (OR = 0.42, 95%CI: 0.22 ∼ 0.84), tea drinking habit for 1–9 years (OR = 0.36, 95%CI: 0.15 ∼ 0.90) and more than 240cc daily (OR = 0.35, 95%CI: 0.17 ∼ 0.72) were negatively associated with MetS. In conclusion, this study suggests that smoking habit was positively associated with MetS, but tea drinking habit was negatively associated with MetS in elderly men dwelling in rural community.

Diet-induced paternal obesity in the absence of diabetes diminishes the reproductive health of two subsequent generations of mice

BACKGROUND

Obesity and related conditions, notably subfertility, are increasingly prevalent. Paternal influences are known to influence offspring health outcome, but the impact of paternal obesity and subfertility on the reproductive health of subsequent generations has been overlooked.

METHODS

A high-fat diet (HFD) was used to induce obesity but not diabetes in male C57Bl6 mice, which were subsequently mated to normal-weight females. First-generation offspring were raised on a control diet and their gametes were investigated for signs of subfertility. Second-generation offspring were generated from both first generation sexes and their gametes were similarly assessed.

RESULTS

We demonstrate a HFD-induced paternal initiation of subfertility in both male and female offspring of two generations of mice. Furthermore, we have shown that diminished reproductive and gamete functions are transmitted through the first generation paternal line to both sexes of the second generation and via the first generation maternal line to second-generation males. Our previous findings that founder male obesity alters the epigenome of sperm, could provide a basis for the developmental programming of subfertility in subsequent generations.

CONCLUSIONS

This is the first observation of paternal transmission of diminished reproductive health to future generations and could have significant implications for the transgenerational amplification of subfertility observed worldwide in humans.

Nonalcoholic fatty liver disease and cardiovascular disease: has the time come for cardiologists to be hepatologists?

Nonalcoholic fatty liver disease (NAFLD) is prevalent in people with the metabolic syndrome and type 2 diabetes and is present in up to one-third of the general population. Evidence is now accumulating that NAFLD is associated with obesity and diabetes and may serve as a predictor of cardiovascular disease (CVD). The possible mechanisms linking NAFLD and CVD include inflammation and oxidative stress, hyperlipidaemia, insulin resistance, and direct impact of NAFLD on coronary arteries and left ventricular dysfunction. In addition, several studies suggest that NAFLD is associated with high risk of CVD and atherosclerosis such as carotid artery wall thickness and lower endothelial flow-mediated vasodilation independently of classical risk factors and components of the metabolic syndrome. It is not yet clear how treatment of NAFLD will modulate the risk of CVD. Furthermore, studies are urgently needed to establish (i) the pathophysiology of CVD with NAFLD and (ii) the benefit of early diagnosis and treatment of CVD in patients with NAFLD. In the absence of biochemical markers, it is crucial that screening and surveillance strategies are adopted in clinical practice in the growing number of patients with NAFLD and at risk of developing CVD. Importantly, the current evidence suggest that statins are safe and effective treatment for CVD in individuals with NAFLD.

Smoking and severity of hepatic fibrosis in nonalcoholic fatty liver disease

BACKGROUND & AIMS

Although many predictors of disease severity of nonalcoholic fatty liver disease (NAFLD) have been proposed, studies of the potential effects of specific environmental exposures on human NAFLD are lacking. Smoking increases insulin resistance. Given the pathophysiological role of insulin resistance in NAFLD, characterization of the influence of smoking in NAFLD is warranted. The aim of this paper was to study the potential association between cigarette smoking and advanced fibrosis in NAFLD.

METHODS

All adults enrolled in the NASH CRN studies, between October 2004 and February 2008, who had liver biopsies, were included (n=1091). Advanced fibrosis was defined as stages 3-4. Analyses were performed.

RESULTS

Significant bivariate associations were demonstrated between advanced fibrosis and age, gender, ethnicity, diabetes, and smoking history. History of smoking ≥ 10 pack-years was more common (p <0.0001) among patients with advanced fibrosis. Multivariate analysis demonstrated an association between smoking history of ≥ 10 pack-years and advanced fibrosis (OR=1.63). Among non-diabetics, history of ≥ 10 pack-years was associated with an OR of 2.48 for advanced fibrosis. High frequencies of advanced fibrosis were observed among diabetics (with or without ≥ 10 pack-years history) and non-diabetics with ≥ 10 pack-years history as compared to non-diabetics without significant smoking history.

CONCLUSIONS

Smoking history was associated with advanced liver fibrosis in this large multicenter cohort of NAFLD patients. The results indicate that smoking may enhance the progression of NAFLD partly through its effect on insulin resistance. Our results are consistent with recent animal studies suggesting that cigarette smoke may aggravate fatty liver. To our knowledge, this is the first study to show that cigarette smoking is associated with increased fibrosis severity in human NALFD, suggesting it may accelerate disease progression. These results may support a formal recommendation of smoking cessation in patients with NAFLD.