Exposure to air pollution is associated with an increased risk of metabolic dysfunction-associated fatty liver disease

The exposome and liver disease - how environmental factors affect liver health

Since the initial development of the exposome concept, much effort has been devoted to the characterisation of the exposome through analytical, epidemiological, and toxicological/mechanistic studies. There is now an urgent need to link the exposome to human diseases and to include exposomics in the characterisation of environment-linked pathologies together with genomics and other omics. Liver diseases are particularly well suited for such studies since major functions of the liver include the detection, detoxification, and elimination of xenobiotics, as well as inflammatory responses. It is well known that several liver diseases are associated with i) addictive behaviours such as alcohol consumption, smoking, and to a certain extent dietary imbalance and obesity, ii) viral and parasitic infections, and iii) exposure to toxins and occupational chemicals. Recent studies indicate that environmental exposures are also significantly associated with liver diseases, and these include air pollution (particulate matter and volatile chemicals), contaminants such as polyaromatic hydrocarbons, bisphenol A and per-and poly-fluorinated substances, and physical stressors such as radiation. Furthermore, microbial metabolites and the "gut-liver" axis play a major role in liver diseases. Exposomics is poised to play a major role in the field of liver pathology. Methodological advances such as the exposomics-metabolomics framework, the determination of risk factors' genomic and epigenomic signatures, and cross-species biological pathway analysis should further delineate the impact of the exposome on the liver, opening the way for improved prevention, as well as the identification of new biomarkers of exposure and effects, and additional therapeutic targets.

Synergistic association of long-term ozone exposure and solid fuel use with biomarkers of advanced fibrosis

This study aims to explore the association of combined exposure to cooking fuel type and ambient ozone (O3) levels with hepatic fibrosis indices among rural adults. A total of 21,010 participants were derived from the Henan Rural Cohort. Information regarding cooking fuel type was collected through a questionnaire, and the concentration of ground-level O3 for each subject was obtained from the Tracking Air Pollution in China (TAP) dataset. A generalized linear model was used to examine the independent association of cooking fuel type or O3 exposure with hepatic fibrosis indices (FIB-4, APRI, and AST/ALT), and their possible interactions with advanced fibrosis were conducted. Compared to clean fuel users, solid fuel users had increased the risk of advanced fibrosis, the adjusted odds ratio (OR) of its assessment by FIB-4 1.240 (1.151, 1.336), by APRI 1.298 (1.185, 1.422), and by AST/ALT 1.135 (1.049, 1.227), respectively. Compared to low O3 exposure, the adjusted ORs of advanced fibrosis assessed by FIB-4, APRI, and AST/ALT in women with high O3 exposure were correspondingly 1.219 (1.138, 1.305), 1.110 (1.017, 1.212), and 0.883 (0.822, 0.949). The adjusted ORs of advanced fibrosis assessed by FIB-4, APRI, and AST/ALT for solid fuel users with high O3 exposure relative to clean fuel users with low O3 exposure in women were 1.557 (1.381, 1.755), 1.427 (1.237, 1.644), and 0.979 (0.863, 1.108), respectively. Significant additive effect of O3 exposure and solid fuel use on FIB-4-defined advanced fibrosis was observed in women, which was quantified by RERI (0.265, 95%CI: 0.052, 0.477), AP (0.170 95%CI: 0.045, 0.295), and SI (1.906, 95%CI: 1.058, 3.432). Solid fuel users with high O3 exposure were significantly associated with elevated hepatic fibrosis indices among rural women, suggesting that poor air quality may induce hepatocellular injury, and women might be more vulnerable to air pollution. The findings indicate that using cleaner fuels in cooking is an effective measure to maintain sustainable development of the environment and gain beneficial effect on human health. Clinical trial registration: The Henan Rural Cohort Study has been registered at the Chinese Clinical Trial Register (registration number: ChiCTR-OOC-15006699). Date of registration: 06 July 2015. http://www.chictr.org.cn/showproj.aspx?proj=11375.

Diesel exhaust particles exposure induces liver dysfunction: Exploring predictive potential of human circulating microRNAs signature relevant to liver injury risk

Diesel exhaust particles (DEP) pollution should be taken seriously because it is an extensive environmental and occupational health concern. Exploring early effect biomarkers is crucial for monitoring and managing DEP-associated health risk assessment. Here, we found that serum levels of 67 miRNAs were dysregulated in DEP exposure group. Notably, 20 miRNAs were identified as each having a significant dose-response relationship with the internal exposure level of DEP. Further, we revealed that the DEP exposure could affect the liver function of subjects and that 7 miRNAs (including the well-known liver injury indicator, miR-122-5p) could serve as the novel epigenetic-biomarkers (epi-biomarkers) to reflect the liver-specific response to the DEP exposure. Importantly, an unprecedented prediction model using these 7 miRNAs was established for the assessment of DEP-induced liver injury risk. Finally, bioinformatic analysis indicated that the unique set of miRNA panel in serum might also contribute to the molecular mechanism of DEP exposure-induced liver damage. These results broaden our understanding of the adverse health outcomes of DEP exposure. Noteworthy, we believe this study could shed light on roles and functions of epigenetic biomarkers from environmental exposure to health outcomes by revealing the full chain of exposure-miRNAs-molecular pathways-disease evidence.

Interactions between long-term ambient particle exposures and lifestyle on the prevalence of hypertension and diabetes: insight from a large community-based survey

INTRODUCTION

Evidence on the interaction of lifestyle and long-term ambient particle (PM) exposure on the prevalence of hypertension, diabetes, particularly their combined condition is limited. We investigate the associations between PM and these outcomes and whether the associations were modified by various lifestyles.

METHODS

This was a large population-based survey during 2019-2021 in Southern China. The concentrations of PM were interpolated and assigned to participants by the residential address. Hypertension and diabetes status were from questionnaires and confirmed with the community health centres. Logistic regression was applied to examine the associations, followed by a comprehensive set of stratified analyses by the lifestyles including diet, smoking, drinking, sleeping and exercise.

RESULTS

A total of 82 345 residents were included in the final analyses. For each 1 μg/m3 increase in PM2.5, the adjusted OR for the prevalence of hypertension, diabetes and their combined condition were 1.05 (95% CI 1.05 to 1.06), 1.07 (95% CI 1.06 to 1.08) and 1.05 (95% CI 1.04 to 1.06), respectively. We observed that the association between PM2.5 and the combined condition was greatest in the group with 4-8 unhealthy lifestyles (OR=1.09, 95% CI 1.06 to 1.13) followed by the group with 2-3 and those with 0-1 unhealthy lifestyle (P interaction=0.026). Similar results and trends were observed in PM10 and/or in those with hypertension or diabetes. Individuals who consumed alcohol, had inadequate sleep duration or had poor quality sleep were more vulnerable.

CONCLUSION

Long-term PM exposure was associated with increased prevalence of hypertension, diabetes and their combined condition, and those with unhealthy lifestyles suffered greater risks of these conditions.

Potential causal links between long-term ambient particulate matter exposure and cerebrovascular mortality: Insights from a large cohort in southern China

Cohort studies conducted in North America and Europe have linked cerebrovascular mortality to long-term exposure to particulate matter (PM). However, limited evidence from large cohorts in high-exposure areas and the traditional approach of association assessment may cause residual confounding issues. In this study, we aimed to investigate the causal links between cerebrovascular mortality and long-term exposure to PM_2.5, PM₁₀, and PM_2.5-10 in an ongoing cohort study with 580,757 participants in southern China. Using satellite-based estimates of PM concentration at a 1-km² spatial resolution, we assigned exposure levels to each participant and used the marginal structural Cox model to assess the association between PM exposure and cerebrovascular mortality while accounting for time-varying covariates. We also explored the potential modification effects of sociodemographic and behavioral factors on the PM-health associations. Adjusted hazard ratios (HR) for overall cerebrovascular mortality were 1.041 (95% confidence interval (CI): 1.034-1.049) and 1.032 (95% CI: 1.026-1.038) for each 1 μg/m³ increase in PM_2.5, and PM₁₀, respectively. Similar trends were observed in the mortality risk from stroke and ischemic stroke, with HRs ranging from 1.040 to 1.069 and 1.025 to 1.052, respectively, across 2 p.m. exposures. The impact of PM exposure was generally more apparent among women, participants with primary school diplomas and below, and the subgroup under low-exposure. Multiple sensitivity analyses confirmed the robustness of the results. In conclusion, this sizable prospective cohort study hypothesizes causal links between long-term PM exposure and cerebrovascular mortality, particularly among vulnerable participants, supporting the rationale for reducing PM concentration in China to reduce cerebrovascular mortality.

Long-term effects of particulate matter on incident cardiovascular diseases in middle-aged and elder adults: The CHARLS cohort study

BACKGROUND

Although there is evidence of long-term effects of particulate matter (PM) on cardiovascular diseases (CVD), researches about long-term effects of PM₁ on CVD are limited. We aimed to examine the long-term effects and magnitude of PM, especially PM₁, on incident CVD in China.

METHODS

We included 6016 participants aged ≥ 45 years without CVD at baseline in 2011 from the China Health and Retirement Longitudinal Study. Personal PM (PM₁, PM_2.5, and PM₁₀) concentrations were estimated using geocoded residential address. Generalized linear mixed models and SHapley Additive exPlanation were utilized to calculate the impacts and contributions of PM on CVD. Sensitivity analyses were used to check the robustness.

RESULTS

After a follow up of 4-year, 481 (7.99 %) participants developed CVD. Per 10 μg/m³ uptick in 1-year average concentrations of PM₁, PM_2.5 and PM₁₀ was associated with a 1.20 [95 % confidence interval (CI): 1.05-1.37], 1.13 (95 % CI: 1.11-1.15), and 1.10 (95 % CI: 1.06-1.13) fold risk of incident CVD, respectively. The 2-year average concentrations of PM₁, PM_2.5 and PM₁₀ were associated with incident CVD, corresponding to a 1.03 (95 % CI: 0.96-1.10), 1.11 (95 % CI: 1.02-1.21), and 1.09 (95 % CI: 1.03-1.15) fold risk, respectively. The SHapley Additive exPlanation values of PM₁, PM_2.5, and PM₁₀ were 0.170, 0.153, and 0.053, respectively, corresponding to the first, second, and fifth among all air pollutants. Effects of PM₁, PM_2.5 and PM₁₀ on CVD remained statistically significant in two-pollutant models. The elderly, males, smokers and alcohol drinkers tended to have slightly higher effects, while the differences were not statistically significant (all P-values > 0.05) between subgroups.

CONCLUSION

Long-term exposure to PM₁, PM_2.5, and PM₁₀ was associated with an increased incidence of CVD. The smaller the particle size, the more important it was for incident CVD indicating that emphasis should be placed on small size of PM.

NAFLD, MAFLD, and beyond: one or several acronyms for better comprehension and patient care

The term non-alcoholic fatty liver disease (NAFLD) has rapidly become the most common type of chronic liver disease. NAFLD points to excessive hepatic fat storage and no evidence of secondary hepatic fat accumulation in patients with "no or little alcohol consumption". Both the etiology and pathogenesis of NAFLD are largely unknown, and a definitive therapy is lacking. Since NAFLD is very often and closely associated with metabolic dysfunctions, a consensus process is ongoing to shift the acronym NAFLD to MAFLD, i.e., metabolic-associated fatty liver disease. The change in terminology is likely to improve the classification of affected individuals, the disease awareness, the comprehension of the terminology and pathophysiological aspects involved, and the choice of more personalized therapeutic approaches while avoiding the intrinsic stigmatization due to the term "non-alcoholic". Even more recently, other sub-classifications have been proposed to concentrate the heterogeneous causes of fatty liver disease under one umbrella. While awaiting additional validation studies in this field, we discuss the main reasons underlying this important shift of paradigm.

Sex, Nutrition, and NAFLD: Relevance of Environmental Pollution

Non-alcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease and represents an increasing public health issue given the limited treatment options and its association with several other metabolic and inflammatory disorders. The epidemic, still growing prevalence of NAFLD worldwide cannot be merely explained by changes in diet and lifestyle that occurred in the last few decades, nor from their association with genetic and epigenetic risk factors. It is conceivable that environmental pollutants, which act as endocrine and metabolic disruptors, may contribute to the spreading of this pathology due to their ability to enter the food chain and be ingested through contaminated food and water. Given the strict interplay between nutrients and the regulation of hepatic metabolism and reproductive functions in females, pollutant-induced metabolic dysfunctions may be of particular relevance for the female liver, dampening sex differences in NAFLD prevalence. Dietary intake of environmental pollutants can be particularly detrimental during gestation, when endocrine-disrupting chemicals may interfere with the programming of liver metabolism, accounting for the developmental origin of NAFLD in offspring. This review summarizes cause-effect evidence between environmental pollutants and increased incidence of NAFLD and emphasizes the need for further studies in this field.

The association between endocrine disrupting chemicals and MAFLD: Evidence from NHANES survey

Previous studies on the association of endocrine-disrupting chemicals (EDCs) with metabolic dysfunction-associated fatty liver disease (MAFLD) are very limited. This study analyzed the association of EDCs exposure with MAFLD among 5073 American adults from the 2017-2018 National Health and Nutrition Examination Survey. The results showed that increased exposure to 3 EDCs metabolites (namely As, DiNP and PFOA) were significantly associated with MAFLD, the odds ratio of which were 1.819 (95% CI: 1.224, 2.702), 1.959 (95% CI: 1.224, 3.136) and 2.148 (95% CI: 1.036, 4.456), respectively. Further, the bayesian kernel machine regression model also revealed that phthalates exposure was strongly connected with the MAFLD, particularly in females and the elderly over 65. Moderating effect analysis suggested that higher body mass index (BMI) and inflammatory diet habit (indicated by dietary inflammatory index) strengthened the association between EDCs and MAFLD, whereas population with higher level of insulin sensitivity showed lower risk. In conclusion, our results suggest that either single or combined exposure to EDCs metabolites is link to MAFLD. Our findings also encourage people to sustain a healthy diet, normal levels of insulin sensitivity and BMI, which may help to alleviate the association of MAFLD risk in exposure to EDCs. These results also help us to better understand the association of EDCs and MAFLD and provide effective evidences for preventing MAFLD from the EDCs exposure aspect.

Association of long-term ambient fine particulate matter (PM2.5) and incident non-alcoholic fatty liver disease in Chinese adults

Air pollution is increasingly recognized as an important environmental risk factor for non-alcoholic fatty liver disease (NAFLD). However, epidemiologic evidence on long-term exposure to high air pollution concentrations with incident NAFLD is still very limited. Here, we constructed a population-based dynamic cohort involving 17,106 subjects who were enrolled between 2005 and 2013 and subsequently followed until 2017, combined with a high-resolution ambient fine particulate matter ≤2.5 μm (PM_2.5) dataset, to investigate the association of long-term PM_2.5 exposure (cumulative annual average levels ranged from 36.67 to 111.16 μg/m³) with NAFLD incidence (N = 4,640). We estimated the adjusted hazard ratio (HR) for incident NAFLD among those exposed to the highest quartile of PM_2.5 was 2.04 [95% confidence interval (CI), 1.80-2.30] compared with individuals exposed to the lowest quartile of PM_2.5. The dose-response relationships for PM_2.5 are non-linear for NAFLD across the exposure distribution. Further stratified analyses revealed that lean (<23 kg/m²), younger (<40-year-old), and women individuals appeared more vulnerable to the harmful effects of PM_2.5 exposure. Our study suggests a greater long-term high ambient PM_2.5 exposure is associated with an increased risk of NAFLD in Chinese adults, particularly in specific groups, including lean, women, and younger people.

Effects of differential regional PM2.5 induced hepatic steatosis and underlying mechanism

Emerging evidence suggests that exposure to PM_2.5 is associated with a high risk of nonalcoholic fatty liver disease (NAFLD). NAFLD is typically characterised by hepatic steatosis. However, the underlying mechanisms and critical components of PM_2.5-induced hepatic steatosis remain to be elucidated. In this study, ten-month-old C57BL/6 female mice were exposed to PM_2.5 from four cities in China (Taiyuan, Beijing, Hangzhou, and Guangzhou) via oropharyngeal aspiration every other day for four weeks. After the exposure period, hepatic lipid accumulation was evaluated by biochemical and histopathological analyses. The expression levels of genes related to lipid metabolism and metabolomic profiles were assessed in the mouse liver. The association between biomarkers of hepatic steatosis (hepatic Oil Red O staining area and serum and liver triglyceride contents) and typical components of PM_2.5 was identified using Pearson correlation analysis. Oil Red O staining and biochemical results indicated that PM_2.5 from four cities significantly induced hepatic lipid accumulation. The most severe hepatic steatosis was observed after Guangzhou PM_2.5 exposure. Moreover, Guangzhou PM_2.5-induced the most significant changes in gene expression associated with lipid metabolism, including increased hepatic fatty acid uptake and lipid droplet formation and decreased fatty acid synthesis and lipoprotein secretion. Contemporaneously, exposure to Guangzhou PM_2.5 significantly perturbed hepatic lipid metabolism. According to metabolomic analysis, disturbed hepatic lipid metabolism was primarily concentrated in linoleic acid, α-linoleic acid, and arachidonic acid metabolism. Finally, correlation analysis revealed that copper (Cu) and other inorganic components, as well as the majority of polycyclic aromatic hydrocarbons (PAHs), were related to changes in biomarkers of hepatic steatosis. These findings showed that PM_2.5 exposure caused hepatic steatosis in aged mice, which could be related to the critical chemical components of PM_2.5. This study provides critical information regarding the components of PM_2.5, which cause hepatic steatosis.

Metabolic dysfunction-associated fatty liver disease increased the risk of subclinical carotid atherosclerosis in China

BACKGROUND AND AIMS

Metabolic dysfunction-associated fatty liver disease (MAFLD) was proposed to substitute NAFLD in 2020. This new term highlights the systematic metabolic disturbances that accompany fatty liver. We evaluated the correlations between MAFLD and subclinical carotid atherosclerosis (SCA) based on a nationwide health examination population in China.

METHODS

We performed a nationwide cross-sectional population and a Beijing retrospective cohort from 2009 to 2017. SCA was defined as elevated carotid intima-media thickness. The multivariable logistic and Cox models were used to analyze the association between MAFLD and SCA.

RESULTS

153,482 participants were included in the cross-sectional study. MAFLD was significantly associated with SCA in fully adjusted models, with an odds ratio of 1.66; 95% confidence interval (CI): 1.62-1.70. This association was consistent in the cohort, with a hazard ratio (HR) of 1.31. The association between baseline MAFLD and incident SCA increased with hepatic steatosis severity. Subgroup analysis showed an interaction between age and MAFLD, with a higher risk in younger groups (HR:1.67, 95% CI: 1.17-2.40).

CONCLUSION

In this large cross-section and cohort study, MAFLD was significantly associated with the presence and development of SCA. Further, the risk was higher among MAFLD individuals with high hepatic steatosis index and young adults.

Mini Review: The Impact of Climate Change on Gastrointestinal Health

Global warming and climate change are important worldwide issues which are a major human health threat. Climate change can affect the gastrointestinal (GI) system in many ways. Increased rainfall events and flooding may be associated with increased GI infections and hepatitis. Climate change could cause changes in gut microbiota, which may impact the pattern of GI diseases. The stress of access to essential needs such as clean water and food, the effects of forced migration, and natural disasters could increase brain-gut axis disorders. The association between air pollution and GI disorders is another challenging issue. There is a lot to do personally and professionally as gastroenterologists regarding climate change.

Cell-free circulating mitochondrial DNA: An emerging biomarker for airborne particulate matter associated with cardiovascular diseases

The association of airborne particulate matter exposure with the deteriorating function of the cardiovascular system is fundamentally driven by the impairment of mitochondrial-nuclear crosstalk orchestrated by aberrant redox signaling. The loss of delicate balance in retrograde communication from mitochondria to the nucleus often culminates in the methylation of the newly synthesized strand of mitochondrial DNA (mtDNA) through DNA methyl transferases. In highly metabolic active tissues such as the heart, mtDNA's methylation state alteration impacts mitochondrial bioenergetics. It affects transcriptional regulatory processes involved in biogenesis, fission, and fusion, often accompanied by the integrated stress response. Previous studies have demonstrated a paradoxical role of mtDNA methylation in cardiovascular pathologies linked to air pollution. A pronounced alteration in mtDNA methylation contributes to systemic inflammation, an etiological determinant for several co-morbidities, including vascular endothelial dysfunction and myocardial injury. In the current article, we evaluate the state of evidence and examine the considerable promise of using cell-free circulating methylated mtDNA as a predictive biomarker to reduce the more significant burden of ambient air pollution on cardiovascular diseases.

Long-term exposure to air pollution and incident non-alcoholic fatty liver disease and cirrhosis: A cohort study

BACKGROUND AND AIMS

Epidemiological evidence regarding the association of air pollution with the risk of non-alcoholic fatty liver disease (NAFLD) is limited. This study was to examine the associations of long-term exposure to various air pollutants and overall air pollution with risk of incident NAFLD as well as cirrhosis, a major liver-related morbidity for NAFLD.

METHODS

Included were 456 687 UK residents. Air pollution data included PM_2.5 , PM_2.5-10 , PM₁₀ , NO₂ and NO_x . A weighted air pollution score was also generated from PM₁₀ and NO_x . Cox proportional hazard models were employed to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

We identified 4978 cases of NAFLD and 1575 cases of incident cirrhosis, over a median follow-up of 11.9 years. PM_2.5 , PM₁₀ , NO₂ and NO_x exposures contributed to the excess risk of NAFLD associated with air pollution score; and the corresponding adjusted HRs (95% CI) were 1.10 (1.05, 1.14), 1.14 (1.09, 1.20), 1.19 (1.13, 1.24) and 1.11 (1.07, 1.15), respectively, for each interquartile range increase in the above specific air pollutants. Similar patterns were also indicated for cirrhosis risk. Alcohol consumption was an effect modifier for the association between air pollution score and NAFLD risk, whereas body mass index modified the association for cirrhosis risk.

CONCLUSION

Long-term exposure to air pollution was associated with risks of NAFLD and cirrhosis among the UK population.

Screening for MAFLD: who, when and how?

Metabolic-associated fatty liver disease (MAFLD) is a highly prevalent disease with increasing prevalence worldwide. Currently, no universal screening methods have been standardized, even when this disease poses a major health burden. MAFLD as a spectrum of diseases can range from simple steatosis, and steatohepatitis to fibrosis and hepatocellular carcinoma. Its extra-hepatic manifestations are vast and include cardiovascular diseases, extra-hepatic malignancies, cognitive and respiratory alterations. Given its extensive damage targets as well as its high prevalence, timely identification of the high-risk population presenting metabolic dysfunction should undergo universal non-invasive screening methods, which can be carried out through blood tests, easy and effective imaging techniques, such as ultrasound, score calculation and general clinical information brought together from primary patient-physician contact.

Can Maternal Exposure to Air Pollution Affect Post-Natal Liver Development?

Emerging evidence suggests that inhalation of particulate matter (PM) can have direct adverse effects on liver function. Early life is a time of particular vulnerability to the effects of air pollution. On that basis, we tested whether in utero exposure to residential PM has an impact on the developing liver. Pregnant mice (C57BL/6J) were intranasally administered 100 µg of PM sampled from residential roof spaces (~5 mg/kg) on gestational days 13.5, 15.5, and 17.5. The pups were euthanized at two weeks of age, and liver tissue was collected to analyse hepatic metabolism (glycogen storage and lipid level), cellular responses (oxidative stress, inflammation, and fibrosis), and genotoxicity using a range of biochemical assays, histological staining, ELISA, and qPCR. We did not observe pronounced effects of environmentally sampled PM on the developing liver when examining hepatic metabolism and cellular response. However, we did find evidence of liver genomic DNA damage in response to in utero exposure to PM. This effect varied depending on the PM sample. These data suggest that in utero exposure to real-world PM during mid-late pregnancy has limited impacts on post-natal liver development.

Shift work and nonalcoholic fatty liver disease incidence among Chinese rail workers: a 4-year longitudinal cohort study

PURPOSE

Occupational harmful factors, such as shift work, are attracting increasing attention as a potential cause of nonalcoholic fatty liver disease (NAFLD). In this study, we aimed to identify the association between shift work and NAFLD incidence in Chinese rail population.

METHODS

A cohort study was conducted among 14,112 rail workers for 4-year follow-up. Shift work frequency and other potential variables were recorded by questionnaires, including demographic, lifestyle, and occupation information. Besides, body mass index, blood pressure, fasting blood glucose, total cholesterol, triglyceride, alanine aminotransferase, and aspartate aminotransferase were measured by anthropometric measurement and blood test. Diagnosis of new NAFLD case was based on abdominal ultrasonography. Cox proportional hazards regression model was used to determine whether shift work has effect on occurrence of NAFLD.

RESULTS

The incidence of NAFLD was 30.43% in total subjects. After adjustment for possible confounders, the RRs of NAFLD were 1.069 (95% CI 0.998-1.146) and 1.179 (95% CI 1.059-1.312) in occasionally shift work group and frequently shift work group respectively, compared to the seldom shift work group. In stratified analyses, the RRs of NAFLD incidence linked to shift work exposure seems increase among female and elder. The results of three sensitivity analyses were similar with main analysis.

CONCLUSIONS

This research provided further evidence of positive harmful effect of shift work on NAFLD incidence in Chinese rail workers, particularly in frequently shift work population. The risk estimate of shift work on NAFLD was higher in female and elder.

Liver fibrosis and MAFLD: the exploration of multi-drug combination therapy strategies

In recent years, the prevalence of metabolic-associated fatty liver disease (MAFLD) has reached pandemic proportions as a leading cause of liver fibrosis worldwide. However, the stage of liver fibrosis is associated with an increased risk of severe liver-related and cardiovascular events and is the strongest predictor of mortality in MAFLD patients. More and more people believe that MAFLD is a multifactorial disease with multiple pathways are involved in promoting the progression of liver fibrosis. Numerous drug targets and drugs have been explored for various anti-fibrosis pathways. The treatment of single medicines is brutal to obtain satisfactory results, so the strategies of multi-drug combination therapies have attracted increasing attention. In this review, we discuss the mechanism of MAFLD-related liver fibrosis and its regression, summarize the current intervention and treatment methods for this disease, and focus on the analysis of drug combination strategies for MAFLD and its subsequent liver fibrosis in recent years to explore safer and more effective multi-drug combination therapy strategies.

Changes in the liver proteome in apoE knockout mice exposed to inhalation of silica nanoparticles indicate mitochondrial damage and impairment of ER stress responses associated with microvesicular steatosis

The adverse effects of air pollution on the cardiovascular system have been well documented. Nonalcoholic fatty liver disease (NAFLD) is an independent risk factor for cardiovascular events. However, the influence of exposure to airborne particles on the development of NAFLD is less recognised. The aim of this study was to investigate the impact of silica nanoparticles (SiNPs) on the development of liver steatosis. We used molecular and proteomic SWATH-MS methods to investigate the changes in the liver proteome of apolipoprotein E-knockout mice (apoE-/- mice) exposed to SiNPs for 4 months in a whole-body exposure chamber. Exposure to SiNPs evoked microvesicular liver steatosis in apoE-/- mice. Quantitative liver proteomics showed significant downregulation of ribosomal proteins and endoplasmic reticulum proteins. Gene expression analysis revealed a reduced level of proteins related to endoplasmic reticulum stress. Treatment with SiNPs decreased mitochondrial membrane potential and increased the production of reactive oxygen species in cultured HepG2 cells. This is the first report that inhalation exposure to SiNPs induces microvesicular steatosis and significant changes in the liver proteome in vivo. Our results highlight the important role of silica and point to the ER stress response and mitochondrial dysfunction as potential mechanisms responsible for the increase in fatty liver by SiNPs.

Silica nanoparticles aggravated the metabolic associated fatty liver disease through disturbed amino acid and lipid metabolisms-mediated oxidative stress

The metabolic associated fatty liver disease (MAFLD) is a public health challenge, leading to a global increase in chronic liver disease. The respiratory exposure of silica nanoparticles (SiNPs) has revealed to induce hepatotoxicity. However, its role in the pathogenesis and progression of MAFLD was severely under-studied. In this context, the hepatic impacts of SiNPs were investigated in vivo and in vitro through using ApoE^-/- mice and free fatty acid (FFA)-treated L02 hepatocytes. Histopathological examinations and biochemical analysis showed SiNPs exposure via intratracheal instillation aggravated hepatic steatosis, lipid vacuolation, inflammatory infiltration and even collagen deposition in ApoE^-/- mice, companied with increased hepatic ALT, AST and LDH levels. The enhanced fatty acid synthesis and inhibited fatty acid β-oxidation and lipid efflux may account for the increased hepatic TC/TG by SiNPs. Consistently, SiNPs induced lipid deposition and elevated TC in FFA-treated L02 cells. Further, the activation of hepatic oxidative stress was detected in vivo and in vitro, as evidenced by ROS accumulation, elevated MDA, declined GSH/GSSG and down-regulated Nrf2 signaling. Endoplasmic reticulum (ER) stress was also triggered in response to SiNPs-induced lipid accumulation, as reflecting by the remarkable ER expansion and increased BIP expression. More importantly, an UPLC-MS-based metabolomics analysis revealed that SiNPs disturbed the hepatic metabolic profile in ApoE^-/- mice, prominently on amino acids and lipid metabolisms. In particular, the identified differential metabolites were strongly correlated to the activation of oxidative stress and ensuing hepatic TC/TG accumulation and liver injuries, contributing to the progression of liver diseases. Taken together, our study showed SiNPs promoted hepatic steatosis and liver damage, resulting in the aggravation of MAFLD progression. More importantly, the disturbed amino acids and lipid metabolisms-mediated oxidative stress was a key contributor to this phenomenon from a metabolic perspective.

Detangling the interrelations between MAFLD, insulin resistance, and key hormones

Metabolic dysfunction-associated fatty liver disease (MAFLD) has increasingly become a significant and highly prevalent cause of chronic liver disease, displaying a wide array of risk factors and pathophysiologic mechanisms of which only a few have so far been clearly elucidated. A bidirectional interaction between hormonal discrepancies and metabolic-related disorders, including obesity, type 2 diabetes mellitus (T2DM), and polycystic ovarian syndrome (PCOS) has been described. Since the change in nomenclature from non-alcoholic fatty liver disease (NAFLD) to MAFLD is based on the clear impact of metabolic elements on the disease, the reciprocal interactions of hormones such as insulin, adipokines (leptin and adiponectin), and estrogens have strongly pointed to the intrinsic links that lead to the heterogeneous epidemiology, clinical presentations, and risk factors involved in MAFLD in different populations. The objective of this work is twofold. Firstly, there is a brief discussion regarding the change in nomenclature as well as epidemiology, risk factors, and pathophysiologic mechanisms other than hormonal effects, which include nutrition and the gut microbiome, as well as genetic and epigenetic influences. Secondly, we review the basis of the most important hormonal factors involved in the development and progression of MAFLD that act both independently and in an interrelated manner.

GA/HbA1c ratio is a simple and practical indicator to evaluate the risk of metabolic dysfunction-associated fatty liver disease in type 2 diabetes: an observational study

BACKGROUND

It is still debatable whether glycated albumin/glycated hemoglobin A1C (GA/HbA1C) ratio is associated with metabolic dysfunction-associated fatty liver disease (MAFLD), and few studies have been conducted in type 2 diabetes mellitus (T2DM). Therefore, we aimed to investigate the association between GA/HbA1C ratio and MAFLD and to evaluate whether GA/HbA1C ratio can be used an indicator of MAFLD in Chinese patients with T2DM.

METHODS

This cross-sectional study consisted of 7117 T2DM patients including 3296 men and 3821 women from real-world settings. Abdominal ultrasonography was performed to diagnose MAFLD. In addition to comparing the clinical characteristics among the GA/HbA1C ratio quartile groups, we also investigated the associations of GA/HbA1C ratio and quartiles with MAFLD in T2DM subjects.

RESULTS

There was a significantly decreased trend in the MAFLD prevalence across the GA/HbA1C ratio quartiles (56.3%, 47.4%, 37.8%, and 35.6% for the first, second, third, and fourth quartile, respectively, P < 0.001 for trend) after adjusting for gender, age, and diabetes duration. Fully adjusted Binary logistic regression indicated that both GA/HbA1C ratio (OR: 0.575, 95% CI: 0.471 to 0.702, P < 0.001) and quartiles (P < 0.001 for trend) were inversely associated with the presence of MAFLD among T2DM patients. Additionally, HOMA2-IR values were clearly increased in the T2DM subjects with MAFLD compared with those without MAFLD (P < 0.001), and markedly increased from the highest to the lowest GA/HbA1C ratio quartile (P < 0.001 for trend).

CONCLUSIONS

GA/HbA1C ratio is closely and negatively associated with MAFLD in T2DM subjects, which may attribute to that GA/HbA1C ratio reflects the degree of insulin resistance. GA/HbA1C ratio may act as a simple and practical indicator to evaluate the risk of MAFLD in T2DM.

Melatonin alleviates PM2.5 -induced glucose metabolism disorder and lipidome alteration by regulating endoplasmic reticulum stress

Exposure to fine particulate matter (PM_2.5 ) was associated with an increased incidence of liver metabolic disease. Melatonin has been shown to prevent liver glucolipid metabolism disorders. However, whether melatonin could rescue PM_2.5 -induced liver metabolic abnormalities remains uncertain. This study was to evaluate the mitigating effect of melatonin on PM_2.5 -accelerated hepatic glucose metabolism imbalance in vivo and in vitro. Schiff periodic acid shiff staining and other results showed that PM_2.5 led to a decrease in hepatic glycogen reserve and an increase in glucose content, which was effectively alleviated by melatonin. Targeted lipidomics is used to identify lipid biomarkers associated with this process, including glycerolipids, glycerophospholipids, and sphingolipids. In addition, gene microarray and quantitative polymerase chain reaction analysis of ApoE^-/- mice liver suggested that PM_2.5 activated the miR-200a-3p and inhibited DNAJB9, and the targeting relationship was verified by luciferase reports for the first time. Further investigation demonstrated that DNAJB9 might motivate endoplasmic reticulum (ER) stress by regulating Ca²⁺ homeostasis, thus altering the protein expression of GSK3B, FOXO1, and PCK2. Meanwhile, melatonin effectively inhibited miR-200a-3p and glucose metabolism disorder. Knockout of miR-200a-3p in L02 cells revealed that miR-200a-3p is indispensable in the damage of PM_2.5 and the therapeutic effect of melatonin. In summary, melatonin alleviated PM_2.5 -induced liver metabolic dysregulation by regulating ER stress via miR-200a-3p/DNAJB9 signaling pathway. Our data provide a prospective targeted therapy for air pollution-related liver metabolism disorders.

The Epidemiological Characteristics of Noncommunicable Diseases and Malignant Tumors in Guiyang, China: Cross-sectional Study

Background

Studies that address the changing characteristics of diseases are of great importance for preventing and controlling the occurrence and development of diseases and for improving health. However, studies of the epidemiological characteristics of noncommunicable diseases (NCDs) and malignant tumors (MTs) of the residents in Guiyang, China, are lacking.

Objective

The aim of this study was to evaluate the prevalences of NCDs and MTs in residents of Guiyang, Guizhou Province, China, and analyze differences among ages, genders, and regions.

Methods

A multistage stratified cluster sampling method was used. Based on the inclusion and exclusion criteria, 81,517 individuals were selected for the study. Of these, 77,381 (94.9%) participants completed the study. Structured questionnaires were used to collect information on demographic characteristics, NCDs, and MTs. The chi-square test (with 95% confidence intervals) was used to analyze differences in disease prevalence among genders, ages, and geographical regions.

Results

The major chronic NCDs of Guiyang residents are obesity, hypertension, and diabetes. MTs in women are mostly breast cancer, cervical cancer, and endometrial cancer, whereas in men, MTs are mainly lung cancer, rectal cancer, and gastric cancer. The prevalences of hypertension and diabetes in women are higher than in men, but the prevalences of lung cancer and gastric cancer in men are higher than in women. The epidemiological characteristics of individuals in different life stages are dissimilar. In terms of regional distribution, the prevalences of the above diseases in the Baiyun and Yunyan districts of Guiyang are relatively high.

Conclusions

Several NCDs (obesity, hypertension, and diabetes) and MTs (women: breast cancer, cervical cancer, and endometrial cancer; men: lung cancer, rectal cancer, and gastric cancer) should be the focus for the prevention and control of chronic diseases in the future. In particular, the Baiyun and Yunyan districts of Guiyang are the important regions to emphasize.

PM2.5 air pollution exposure and nonalcoholic fatty liver disease in the Nationwide Inpatient Sample

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease. Particulate matter air pollution <2.5 μm in diameter (PM_2.5) is a ubiquitous exposure primarily produced from fossil fuel combustion. Previous epidemiologic studies have been mixed. The objective of this study was to examine the association between ambient PM_2.5 exposure and NAFLD among hospitalized patients in the Nationwide Inpatient Sample (NIS).

METHODS

We conducted a cross-sectional analysis of hospitalizations from 2001 to 2011 using the NIS, the largest nationally representative all-payer inpatient care administrative database in the United States. Average annual PM_2.5 exposure was estimated by linking census tracts (based on NIS-provided hospital ZIP Codes) with a spatiotemporal exposure model. Clinical conditions were identified using hospital discharge diagnosis codes. Multivariable logistic regression incorporating discharge weights was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between PM_2.5 exposure and odds of NAFLD among hospitalized patients adjusting for age, sex, race/ethnicity, year, individual- and area-level socioeconomic status, urbanicity, region, obesity, diabetes, metabolic syndrome, impaired fasting glucose, dyslipidemia, hypertension, obstructive sleep apnea, and smoking.

RESULTS

There were 269,705 hospitalized patients with NAFLD from 2001 to 2011 (total unweighted n = 45,433,392 hospitalizations). Higher ambient PM_2.5 exposure was associated with increased odds of NAFLD among hospitalized patients (adjusted OR: 1.24 per 10 μg/m³ increase, 95% CI 1.15-1.33, p < 0.01). There were statistically significant interactions between PM_2.5 exposure and age, race/ethnicity, diabetes, smoking, and region, with stronger positive associations among patients who were aged ≥45 years, non-Hispanic White or Asian/Pacific Islander, non-diabetics, non-smokers, or in the Midwest and West regions, respectively.

CONCLUSIONS

In this nationwide cross-sectional analysis of the NIS database, there was a positive association between ambient PM_2.5 exposure and odds of NAFLD among hospitalized patients. Future research should examine the effects of long-term historical PM_2.5 exposure and incident NAFLD cases.

The underlying mechanism of PM2.5-induced ischemic stroke

Under the background of global industrialization, PM_2.5 has become the fourth-leading risk factor for ischemic stroke worldwide, according to the 2019 GBD estimates. This highlights the hazards of PM_2.5 for ischemic stroke, but unfortunately, PM_2.5 has not received the attention that matches its harmfulness. This article is the first to systematically describe the molecular biological mechanism of PM_2.5-induced ischemic stroke, and also propose potential therapeutic and intervention strategies. We highlight the effect of PM_2.5 on traditional cerebrovascular risk factors (hypertension, hyperglycemia, dyslipidemia, atrial fibrillation), which were easily overlooked in previous studies. Additionally, the effects of PM_2.5 on platelet parameters, megakaryocytes activation, platelet methylation, and PM_2.5-induced oxidative stress, local RAS activation, and miRNA alterations in endothelial cells have also been described. Finally, PM_2.5-induced ischemic brain pathological injury and microglia-dominated neuroinflammation are discussed. Our ultimate goal is to raise the public awareness of the harm of PM_2.5 to ischemic stroke, and to provide a certain level of health guidance for stroke-susceptible populations, as well as point out some interesting ideas and directions for future clinical and basic research.

Nonalcoholic steatohepatitis and hepatocellular carcinoma: Beyond the boundaries of the liver

The burden of non-alcoholic steatohepatitis (NASH) related hepatocellular carcinoma (HCC) is drawing attention due to the emerging epidemic of obesity and metabolic syndrome and is expected to increase in the near future. Antidiabetic medications, air pollutants, and newer genetic mutations are latest concerns as risk factors for HCC development in patients with NASH. Although molecular signatures are very accurate, they are not cost-effective and cannot be applied in larger population due to logistic issues. We need multicentric longitudinal studies including diverse geographical areas to evaluate the complex interplay of different risk factors and genetics in these patients.

The prevalence of MAFLD and its association with atrial fibrillation in a nationwide health check-up population in China

BACKGROUND AND AIMS

The epidemiological characteristics of MAFLD and its relationship with atrial fibrillation (AF) are limited in China. Therefore, we explored the epidemiological characteristics of MAFLD from adults along with the association of MAFLD and 12-ECG diagnosed AF in a nationwide population from health check-up centers.

METHODS

This observational study used cross-sectional and longitudinal studies with 2,083,984 subjects from 2009 to 2017. Age-, sex-, and regional-standardized prevalence of MAFLD was estimated. Latent class analysis (LCA) was used to identify subclusters of MAFLD. Multivariable logistic regression and mixed-effects Cox regression models were used to analyze the relationship between MAFLD and AF.

RESULTS

The prevalence of MAFLD increased from 22.75% to 35.58% during the study period, with higher rates in males and populations with high BMI or resided in northern regions. The MAFLD population was clustered into three classes with different metabolic features by LCA. Notably, a high proportion of MAFLD patients in all clusters had overweight and prediabetes or diabetes. The MAFLD was significantly associated with a higher risk of AF in the cross-sectional study and in the longitudinal study. In addition, the coexistence of prediabetes or diabetes had the largest impact on subsequent AF.

CONCLUSION

Our findings suggested a high prevalence of MAFLD and a high prevalence of other metabolic diseases in the MAFLD population, particularly overweight and glucose dysregulation. Moreover, MAFLD was associated with a significantly higher risk for existing and subsequent subclinical AF in the Chinese population.

Explore the Relationship Between Short-Term Ambient Air Pollution Exposure and Daily Outpatient Visits for Metabolic Related Fatty Liver

Background

Many studies have shown that the pollution of fine particles in the air is related to the incidence of chronic diseases. However, research on air pollution and metabolism-associated fatty liver disease (MAFLD) is limited.

Objective

The purpose of this study was to explore the relationship between short-term ambient air pollution and daily outpatient visits for metabolic-related fatty liver.

Methods

We used a quasi-Poisson regression generalized additive model to stratify analyses by season, age, and gender.

Results

From January 1, 2017, to August 31, 2019, 10,562 confirmed MAFLD outpatient visits were recorded. A 10 µg/m³ increase of fine particular matter (PM10and PM2.5) and NO₂ concentrations corresponding with percent change were 0.82 (95% confidence interval [CI], 0.49–1.15), 0.57 (95% CI, 0.18–0.98), and 0.86 (95% CI, 0.59–1.13) elevation in MAFLD outpatient visits. In terms of season, the impact estimates of NO₂ and PM2.5% change were 3.55 (95% CI, 1.23–5.87) and 1.12 (95% CI, 0.78–1.46) in the hot season and transition season, respectively. Compared with the warm season, the impact estimates of PM10were more significant in the cool season: 2.88 (95% CI, 0.66–5.10). NO₂ has the greatest effect in the transition season, whereas PM10 has the greatest highest effect in the cool and hot seasons. Compared with other pollutants, PM2.5 has the greatest impact in the age stratification, which percent change are 2.69 (95% CI, 0.77–5.61) and 2.88 (95% CI, 0.37–6.40) respectively. The impact values of PM2.5 in male and female percent change were 3.60 (95% CI, 0.63–6.57) and 1.65 (95% CI, 1.05–2.25), respectively.

Conclusion

This study shows that the air pollutants are related to the number of outpatient visits for MAFLD. The effects of different air pollutants on MAFLD outpatient visits were different by season, ages, and gender.

Non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis belongs to the spectrum of metabolic-associated fatty liver diseases characterized by steatosis linked to obesity, diabetes, metabolic syndrome, dyslipidemia and immune-mediated disorders. The main features of MAFLD include high prevalence, heterogeneity, complexity and dynamic disease. Pruritus and asthenia are the main clinical manifestation that impact on quality of life and patient-reported outcomes. Biochemical or imagen-based non-invasive test have been implemented in the diagnostic process. Liver biopsy remains as the gold standard. Therapeutic options included life-style intervention. Mediterranean hypocaloric Diet to lose weight, exercise to fight sarcopenia and alcohol abstinence. In non-responders, drug-therapy focusing on obesity, diabetes and fibrosis using sequentially or combined to promote steatosis, inflammation and fibrosis regression.

Combined exposure to PM2.5 and high-fat diet facilitates the hepatic lipid metabolism disorders via ROS/miR-155/PPARγ pathway

Environmental fine particulate matter (PM_2.5), which has attracted worldwide attention, is associated with the progression of metabolic-associated fatty liver disease (MAFLD). However, it is unclear whether dietary habit exacerbate liver damage caused by PM_2.5. The current study aimed to investigate the combined negative effects of PM_2.5 and high-fat diet (HFD) on liver lipid metabolism in C57BL/6J mice. Histopathological and Oil-Red O staining analysis illustrated that PM_2.5 exposure resulted in increased liver fat content in HFD-fed C57BL/6J mice, but not in standard chow diet (STD)-fed mice. And there was a synergistic effect between PM_2.5 and HFD on hepatic lipotoxicity. The increased ROS levels and augmented oxidative damage were evaluated in liver tissue of mice treated with PM_2.5 and HFD together. In addition, excessive ROS production could activate the miR-155/peroxisome proliferator-activated receptor gamma (PPARγ) pathway, including up-regulation of lipid accumulation-related protein expressions of recombinant liver X receptor alpha (LXRα), sterol regulatory element binding protein-1 (SREBP-1), stearoyl-CoA desaturase-1 (SCD1), fatty acid synthase (FAS) and acetyl-CoA carboxylase 1 (ACC1).The use of miR-155 inhibitors demonstrated the indispensable role of miR-155 in the activation of lipid-regulated proteins by PM_2.5 and palmitic acid (PA). Collectively, altering high-fat dietary habits could protect against MAFLD motivated by air pollution, and miR-155 might be an effective preventive and therapeutic target for this process.

Global Prevalence and Clinical Characteristics of Metabolic-associated Fatty Liver Disease: A Meta-Analysis and Systematic Review of 10 739 607 Individuals

BACKGROUND AND AIMS

Metabolic-associated fatty liver disease (MAFLD) was proposed as a better definition of nonalcoholic fatty liver disease (NAFLD) to encompass the metabolic dysregulation associated with NAFLD. This redefinition challenges our understanding of the disease. Hence, this study sought to conduct an updated analysis of the prevalence, clinical characteristics, and associated factors of MAFLD, with a further sensitivity analysis done based on lean and nonobese MAFLD individuals.

METHODS

Medline and Embase databases were searched to include articles on MAFLD. Meta-analysis of proportions was conducted using the generalized linear mix model. Associating factors were evaluated in conventional pairwise meta-analysis with sensitivity analysis on lean and nonobese MAFLD.

RESULTS

From pooled analysis involving 3 320 108 individuals, the overall prevalence of MAFLD was 38.77% (95% CI 32.94% to 44.95%); 5.37% (95% CI 4.36% to 6.59%) and 29.78% (95% CI 26.06% to 33.79%) of lean and nonobese individuals, respectively, had MAFLD. Metabolic complications such as hypertension [odds ratio (OR) 2.63, 95% CI 1.85 to 3.74, P < 0.0001 and OR 2.03; 95% CI 1.74 to 2.38, P < 0.0001, respectively] and diabetes (OR 3.80, 95% CI 2.65 to 5.43, P < 0.0001 and OR 3.46, 95% CI 2.81 to 4.27, P < 0.0001, respectively) were found as significant associating factors associated with lean and nonobese MAFLD.

CONCLUSIONS

This meta-analysis supports previous studies in reporting MAFLD to affect more than a third of the global population. While exploration of the pathogenic basis of fatty liver disease without metabolic dysregulation is required, the emphasis on management of concomitant metabolic disease in MAFLD can improve multidisciplinary efforts in managing the complex disease.

Long-Term Exposure to Fine Particulate Matter and the Risk of Chronic Liver Diseases: A Meta-Analysis of Observational Studies

Although fine particulate matter (PM2.5) is a known carcinogen, evidence of the association between PM2.5 and chronic liver disease is controversial. In the present meta-analysis study, we reviewed epidemiological studies to strengthen evidence for the association between PM2.5 and chronic liver disease. We searched three online databases from 1990 up to 2022. The random-effect model was applied for detection of overall risk estimates. Sixteen eligible studies, including one cross-sectional study, one retrospective cohort study, and 14 prospective cohort studies, fulfilled inclusion criteria with more than 330 thousand participants from 13 countries. Overall risk estimates of chronic liver disease for 10 μg/m3 increase in PM2.5 was 1.27 (95% confidence interval (CI): 1.19−1.35, p < 0.001). We further analyzed the relationship between PM2.5 exposure and different chronic liver diseases. The results showed that increments in PM2.5 exposure significantly increased the risk of liver cancer, liver cirrhosis, and fatty liver disease (hazard ratio (HR) = 1.23, 95% CI: 1.14−1.33; HR = 1.17, 95% CI: 1.06−1.29; HR = 1.51, 95% CI: 1.09−2.08, respectively). Our meta-analysis indicated long-term exposure to PM2.5 was associated with increased risk of chronic liver disease. Moreover, future researches should be focused on investigating subtypes of chronic liver diseases and specific components of PM2.5.

Prenatal Pollutant Exposures and Hypothalamic Development: Early Life Disruption of Metabolic Programming

Environmental contaminants in ambient air pollution pose a serious risk to long-term metabolic health. Strong evidence shows that prenatal exposure to pollutants can significantly increase the risk of Type II Diabetes (T2DM) in children and all ethnicities, even without the prevalence of obesity. The central nervous system (CNS) is critical in regulating whole-body metabolism. Within the CNS, the hypothalamus lies at the intersection of the neuroendocrine and autonomic systems and is primarily responsible for the regulation of energy homeostasis and satiety signals. The hypothalamus is particularly sensitive to insults during early neurodevelopmental periods and may be susceptible to alterations in the formation of neural metabolic circuitry. Although the precise molecular mechanism is not yet defined, alterations in hypothalamic developmental circuits may represent a leading cause of impaired metabolic programming. In this review, we present the current knowledge on the links between prenatal pollutant exposure and the hypothalamic programming of metabolism.

Health and Clinical Impacts of Air Pollution and Linkages with Climate Change

Air Pollution Impacts and Climate Change LinksAs part of the NEJM Group series on climate change, Keswani and colleagues review the linkages between climate change and air pollution and suggest strategies that clinicians may use to mitigate the adverse health impacts of air pollution.

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.

Long-term exposure to air pollution, habitual physical activity and risk of non-alcoholic fatty liver disease: A prospective cohort study

BACKGROUND

Emerging studies suggest a positive association between air pollution exposure and risk of non-alcoholic fatty liver disease (NAFLD), however, the combined effects of long-term exposure to air pollution, physical activity (PA), and risk of NAFLD is unclear.

METHODS

We included 58,026 Taiwan residents who received a standard medical screening program between 2001 and 2016. Levels of fine particulate matter (PM2.5) at each participant's residential address were estimated using multiple satellite-based aerosol optical depth data combined with a chemical transport model. PA volume was calculated as hours of metabolic equivalent tasks per week (MET-h/week) based on a standard self-administered questionnaire. Incident NAFLD was defined as the first occurrence of a fatty liver index (FLI) value > 30 or a hepatic steatosis index (HSI) value > 36 in participants without NAFLD at the baseline. Time-varying Cox regression was used to evaluate the combined effects of PA and PM2.5.

RESULTS

Exposure to PM2.5 was positively associated with NAFLD. A 1 μg/m3 increase in PM2.5 above 23.5 μg/m3 was associated with a hazard ratio (HR) of 1.06 (95% CI: 1.04, 1.09) and 1.05 (95% CI: 1.03, 1.07) for NAFLD identified by FLI and HSI, respectively. Performing PA was inversely associated with NAFLD. Compared with participants in high PM2.5 [≥ 27.5 μg/m3]-very low PA [< 3.75 MET-h/week] group, low PM2.5 [< 23.5 μg/m3]-very high PA [≥ 25.50 MET-h/week] group had a 57% (95% CI: 50%, 63%) and 42% (95% CI: 33%, 50%) lower risk of NAFLD defined by FLI and HSI, respectively. We found no evidence of any additive or multiplicative interaction between PA and PM2.5.

CONCLUSION

Long-term PM2.5 exposure was positively associated with NAFLD, whereas performing PA was inversely associated with NAFLD. The benefits of PA on NAFLD remained stable in participants exposed to various PM2.5 levels.

Time to Consider the "Exposome Hypothesis" in the Development of the Obesity Pandemic

The obesity epidemic shows no signs of abatement. Genetics and overnutrition together with a dramatic decline in physical activity are the alleged main causes for this pandemic. While they undoubtedly represent the main contributors to the obesity problem, they are not able to fully explain all cases and current trends. In this context, a body of knowledge related to exposure to as yet underappreciated obesogenic factors, which can be referred to as the "exposome", merits detailed analysis. Contrarily to the genome, the "exposome" is subject to a great dynamism and variability, which unfolds throughout the individual's lifetime. The development of precise ways of capturing the full exposure spectrum of a person is extraordinarily demanding. Data derived from epidemiological studies linking excess weight with elevated ambient temperatures, in utero, and intergenerational effects as well as epigenetics, microorganisms, microbiota, sleep curtailment, and endocrine disruptors, among others, suggests the possibility that they may work alone or synergistically as several alternative putative contributors to this global epidemic. This narrative review reports the available evidence on as yet underappreciated drivers of the obesity epidemic. Broadly based interventions are needed to better identify these drivers at the same time as stimulating reflection on the potential relevance of the "exposome" in the development and perpetuation of the obesity epidemic.