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

Metadherin-driven promotion of cancer stem cell phenotypes and its effect on immunity in hepatocellular carcinoma

In this editorial we provide commentary on the article published by Wang et al, featured in the recent issue of the World Journal of Gastroenterology in 2024. We focus on the metadherin (MTDH), also known as astrocyte elevated gene-1 or lysine rich CEACAM1, and its effects on cancer stem cells (CSCs) and immunity in hepatocellular carcinoma (HCC). HCC is the most common primary liver cancer and one of the leading causes of cancer-related deaths worldwide. Most HCC cases develop in the context of liver cirrhosis. Among the pivotal mechanisms of carcinogenesis are gene mutations, dysregulation of diverse signaling pathways, epigenetic alterations, hepatitis B virus-induced hepatocarcinogenesis, chronic inflammation, impact of tumor microenvironment, oxidative stress. Over the years, extensive research has been conducted on the MTDH role in various tumor pathologies, such as lung, breast, ovarian, gastric, hepatocellular, colorectal, renal carcinoma, neuroblastoma, melanoma, and leukemias. Specifically, its involvement in tumor development processes including transformation, apoptosis evasion, angiogenesis, invasion, and metastasis via multiple signaling pathways. It has been demonstrated that knockdown or knockout of MTDH disrupt tumor development and metastasis. In addition, numerous reports have been carried out regarding the MTDH influence on HCC, demonstrating its role as a predictor of poor prognosis, aggressive tumor phenotypes prone to metastasis and recurrence, and exhibiting significant potential for therapy resistance. Finally, more studies finely investigated the influence of MTDH on CSCs. The CSCs are a small subpopulation of tumor cells that sharing traits with normal stem cells like self-renewal and differentiation abilities, alongside a high plasticity that alters their phenotype. Beyond their presumed role in tumor initiation, they can drive also disease relapse, metastasis, and resistance to chemo and radiotherapy.

Hues of risk: investigating genotoxicity and environmental impacts of azo textile dyes

The textile industry, with its extensive use of dyes and chemicals, stands out as a significant source of water pollution. Exposure to certain textile dyes, such as azo dyes and their breakdown products like aromatic amines, has been associated with health concerns like skin sensitization, allergic reactions, and even cancer in humans. Annually, the worldwide production of synthetic dyes approximates 7 × 107 tons, of which the textile industry accounts for over 10,000 tons. Inefficient dyeing procedures result in the discharge of 15-50% of azo dyes, which do not adequately bind to fibers, into wastewater. This review delves into the genotoxic impact of azo dyes, prevalent in the textile industry, on aquatic ecosystems and human health. Examining different families of textile dye which contain azo group in their structure such as Sudan I and Sudan III Sudan IV, Basic Red 51, Basic Violet 14, Disperse Yellow 7, Congo Red, Acid Red 26, and Acid Blue 113 reveals their carcinogenic potential, which may affect both industrial workers and aquatic life. Genotoxic and carcinogenic characteristics, chromosomal abnormalities, induced physiological and neurobehavioral changes, and disruptions to spermatogenesis are evident, underscoring the harmful effects of these dyes. The review calls for comprehensive investigations into the toxic profile of azo dyes, providing essential insights to safeguard the aquatic ecosystem and human well-being. The importance of effective effluent treatment systems is underscored to mitigate adverse impacts on agricultural lands, water resources, and the environment, particularly in regions heavily reliant on wastewater irrigation for food production.

High plasma interleukin-6 level, but not IL-6 gene variants, as a predictive marker for the development of hepatocellular carcinoma in a Moroccan population

Chronic inflammation triggered by hepatitis B (HBV) and hepatitis C (HCV) viruses elevates interleukin 6 (IL-6) levels, activating pathways that cause liver damage and contribute to hepatocellular carcinoma (HCC) development. In this study, we assessed IL-6 levels and explored the correlation between the rs1800795 and rs1800797 variants of the IL-6 gene and the risk of developing HCC. We conducted a case-control study involving 314 participants. Among them, 157 were HCC patients (94 anti-HCV, 22 HBsAg and 41 metabolic dysfunction-associated steatotic liver disease [MASLD]) and 157 controls. Genotyping for IL-6 rs1800795 and rs1800797 polymorphisms was performed using real-time polymerase chain reaction (PCR). Additionally, plasma IL-6 levels were determined using enzyme-linked immunosorbent assay. The IL-6 levels were notably higher in patients compared to controls (p < .0001). Among HCC patients, those with MASLD exhibited higher plasma IL-6 levels than those with HCV and HBV (p = .003). In male HCC patients, IL-6 levels were significantly elevated compared to controls (p < .0001). Similarly, female patients showed significantly higher IL-6 levels compared to female controls, though still lower than in male HCC patients (p = .023). However, no significant difference was observed in IL-6 levels between male and female HCC patients (p = .129). Contrastingly, the genotype and allele distributions of the rs1800795 and rs1800797 polymorphisms in the IL-6 gene displayed no association with HCC development (all p > .005). In Moroccan HCC patients, chronic liver inflammation is characterized by elevated levels of IL-6, potentially playing a role in the progression of liver disease and tumourigenesis.

Inverse association between plasma chlordecone concentrations and progression of alcoholic liver fibrosis: the role of liver metabolism

BACKGROUND AND AIMS

Chlordecone is a persistent organochlorinated insecticide, extensively used in the French West Indies and has been contaminating the population for more than thirty years. Its potentiation effect on hepatotoxic agents has been demonstrated in animal models. We investigated the relationship between environmental exposure to chlordecone and the progression of liver fibrosis.

METHODS

This study included 182 consecutive patients with chronic alcoholic hepatitis whose liver fibrosis was assessed using non-invasive methods. Measured plasma chlordecone concentrations at inclusion were used as surrogate of long-term exposure under steady-state conditions. As the pharmacokinetic processing of chlordecone is largely determined by the liver, we used a human physiologically based pharmacokinetic model to predict plausible changes in the steady-state blood chlordecone concentrations induced by liver fibrosis.

RESULTS

With a median follow-up of 27.1 years after the onset of alcohol consumption, we found a significant decrease in the risk of advanced liver fibrosis with increasing plasma chlordecone concentration (adjusted hazard ratio = 0.56; 95% confidence interval: 0.34-0.95 for the highest vs. lowest tertile, p = 0.04). Changes induced by liver fibrosis influenced the pharmacokinetic processing of chlordecone, resulting in substantial modifications in its steady-state blood concentrations.

CONCLUSION

According to this human model of coexposure to alcohol, reverse causality is the most plausible explanation of this inverse association between plasma chlordecone concentrations and progression of liver fibrosis. This study underlines the importance of considering the pharmacokinetic of environmental contaminants in epidemiological studies when biomarkers of exposure are used to investigate their own impact on the liver.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03373396.

Nicotine promotes development of bile duct ligation-induced liver fibrosis by increasing expression of nicotinic acetylcholine receptors in rats

Aim of the study

Liver fibrosis and cigarette smoking seem to be directly linked. Nicotine, as an agonist of nicotinic acetylcholine receptors (nAChRs), induces many downstream signaling pathways. The pathways through which nicotine affects the process of liver fibrosis have not been clarified. The present study aimed to investigate the nicotine-induced effects on fibrosis progression in cholestatic rats.

Material and methods

First, the Wistar rats were subjected to sham or bile duct ligation (BDL) surgery. The rats were treated with low and high doses of nicotine (1 or 10 mg/kg) for three weeks. They were monitored for their body weights before and 21 days after BDL. Also, spleens were weighed to calculate the spleen/body weight ratio. Ductular proliferation and fibrosis were evaluated using hematoxylin and eosin (H&E) as well as Masson's trichrome staining. The mRNA expression of α4nAChR, α7nAChR, and fibrosis gene α-smooth muscle actin (α-SMA) was measured by real-time PCR.

Results

The findings showed that nicotine promotes the development of BDL-induced liver fibrosis. The ratio of spleen/body weight was significantly affected by nicotine exposure. H&E and Masson's trichrome staining showed that the level of liver fibrosis was higher in the cholestatic BDL groups, and this effect was significantly augmented in the nicotine-treated rats. Also, α4nAChR, α7nAChR, and α-SMA expression was observed in the BDL rats and increased following nicotine treatment.

Conclusions

The activation of nAChR triggers biliary proliferation and liver fibrosis. Studying the intracellular mechanism of nicotine and alteration in the expression of nicotinic receptors following nicotine exposure can be useful both in diagnosing nicotine-related diseases and finding new treatment strategies.

Altered metabolome and microbiome associated with compromised intestinal barrier induced hepatic lipid metabolic disorder in mice after subacute and subchronic ozone exposure

Exposure to ozone has been associated with metabolic disorders in humans, but the underlying mechanism remains unclear. In this study, the role of the gut-liver axis and the potential mechanism behind the metabolic disorder were investigated by histological examination, microbiome and metabolome approaches in mice during the subacute (4-week) and subchronic (12-week) exposure to 0.5 ppm and 2.5 ppm ozone. Ozone exposure resulted in slowed weight gain and reduced hepatic lipid contents in a dose-dependent manner. After exposure to ozone, the number of intestinal goblet cells decreased, while the number of tuft cells increased. Tight junction protein zonula occludens-1 (ZO-1) was significantly downregulated, and the apoptosis of epithelial cells increased with compensatory proliferation, indicating a compromised chemical and physical layer of the intestinal barrier. The hepatic and cecal metabolic profiles were altered, primarily related to lipid metabolism and oxidative stress. The abundance of Muribaculaceae increased dose-dependently in both colon and cecum, and was associated with the decrease of metabolites such as bile acids, betaine, and L-carnitine, which subsequently disrupted the intestinal barrier and lipid metabolism. Overall, this study found that subacute and subchronic exposure to ozone induced metabolic disorder via disturbing the gut-liver axis, especially the intestinal barrier. These findings provide new mechanistic understanding of the health risks associated with environmental ozone exposure and other oxidative stressors.

A Chinese longitudinal maternity cohort study (2013-2021) on intrahepatic cholestasis phenotypes: Risk associations from environmental exposure to adverse pregnancy outcomes

Intrahepatic cholestasis of pregnancy (ICP) is an idiopathic disease that occurs during mid-to-late pregnancy and is associated with various adverse pregnancy outcomes, including intrauterine fetal demise. However, since the underlying cause of ICP remains unclear, there is an ongoing debate on the phenotyping criteria used in the diagnostic process. Here, we identified single- and multi-symptomatic ICP (ICP-S and ICP-M) in 104,221 Chinese females from the ZEBRA maternity cohort, with the objective of exploring the risk implications of the two phenotypes on pregnancy outcomes and from environmental exposures. We employed multivariate binary logistic regression to estimate confounder-adjusted odds ratios and found that ICP-M was more strongly associated with preterm birth and low birth weight compared to ICP-S. Throughout pregnancy, incremental exposure to PM2.5, O3, and greenness could alter ICP risks by 17.3%, 12.5%, and -2.3%, respectively, with more substantial associations observed with ICP-M than with ICP-S. The major scientific advancements lie in the elucidation of synergistic risk interactions between pollutants and the protective antagonistic effects of greenness, as well as highlighting the risk impact of preconceptional environmental exposures. Our study, conducted in the context of the "three-child policy" in China, provides epidemiological evidence for policy-making to safeguard maternal and neonatal health.

Detection of Trace Elements Se, Cu, and Zn Levels in Biological Samples of Drug Abusers: Halani Sindh, Pakistan

Illicit drug use has become a global issue, posing significant health, socioeconomic, and cultural risks. The study examined essential trace metals: selenium, zinc, and copper in blood concentrations, as well as in serum and scalp hair samples, from 240 male drug-abuse subjects/patients aged 18-45, categorized into three age groups. The study compared 45 healthy subjects of the same age group using an acid digestion method supported by a microwave oven during sample preparation. The technique of atomic absorption spectrometry was employed to identify essential and toxic elements, utilizing certified reference materials for accuracy. According to a recent study, plasma zinc and selenium concentrations in drug abusers are lower than those in referent subjects, potentially increasing vulnerability to infection due to poor nutritional status or other contaminants.

Non-linear association between long-term air pollution exposure and risk of metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Metabolic Dysfunction-associated Steatotic Liver Disease (MASLD) has become a global epidemic, and air pollution has been identified as a potential risk factor. This study aims to investigate the non-linear relationship between ambient air pollution and MASLD prevalence.

METHOD

In this cross-sectional study, participants undergoing health checkups were assessed for three-year average air pollution exposure. MASLD diagnosis required hepatic steatosis with at least 1 out of 5 cardiometabolic criteria. A stepwise approach combining data visualization and regression modeling was used to determine the most appropriate link function between each of the six air pollutants and MASLD. A covariate-adjusted six-pollutant model was constructed accordingly.

RESULTS

A total of 131,592 participants were included, with 40.6% met the criteria of MASLD. "Threshold link function," "interaction link function," and "restricted cubic spline (RCS) link functions" best-fitted associations between MASLD and PM2.5, PM10/CO, and O3 /SO2/NO2, respectively. In the six-pollutant model, significant positive associations were observed when pollutant concentrations were over: 34.64 µg/m3 for PM2.5, 57.93 µg/m3 for PM10, 56 µg/m3 for O3, below 643.6 µg/m3 for CO, and within 33 and 48 µg/m3 for NO2. The six-pollutant model using these best-fitted link functions demonstrated superior model fitting compared to exposure-categorized model or linear link function model assuming proportionality of odds.

CONCLUSION

Non-linear associations were found between air pollutants and MASLD prevalence. PM2.5, PM10, O3, CO, and NO2 exhibited positive associations with MASLD in specific concentration ranges, highlighting the need to consider non-linear relationships in assessing the impact of air pollution on MASLD.

Unraveling the molecular links between benzopyrene exposure, NASH, and HCC: an integrated bioinformatics and experimental study

Benzopyrene (B[a]P) is a well-known carcinogen that can induce chronic inflammation and fibrosis in the liver, leading to liver disease upon chronic exposure. Nonalcoholic steatohepatitis (NASH) is a chronic liver condition characterized by fat accumulation, inflammation, and fibrosis, often resulting in hepatocellular carcinoma (HCC). In this study, we aimed to investigate the intricate connections between B[a]P exposure, NASH, and HCC. Through comprehensive bioinformatics analysis of publicly available gene expression profiles, we identified differentially expressed genes (DEGs) associated with B[a]P exposure, NASH, and liver cancer. Furthermore, network analysis revealed hub genes and protein-protein interactions, highlighting cellular metabolic dysfunction and disruption of DNA damage repair in the B[a]P-NASH-HCC process. Notably, HSPA1A and PPARGC1A emerged as significant genes in this pathway. To validate their involvement, we conducted qPCR analysis on cell lines and NASH mouse liver tissues and performed immunohistochemistry labeling in mouse and human HCC liver sections. These findings provide crucial insights into the potential regulatory mechanisms underlying benzopyrene-induced hepatotoxicity, shedding light on the pathogenesis of B[a]P-associated NASH and HCC. Moreover, our study suggests that HSPA1A and PPARGC1A could serve as promising therapeutic targets. Enhancing our understanding of their regulatory roles may facilitate the development of targeted therapies, leading to improved patient outcomes.

A Single-Step Immunocapture Assay to Quantify HCC Exosomes Using the Highly Sensitive Fluorescence Nanoparticle-Tracking Analysis

Introduction

Extracellular vesicles could serve as a non-invasive biomarker for early cancer detection. However, limited methods to quantitate cancer-derived vesicles in the native state remain a significant barrier to clinical translation.

Aim

This research aims to develop a rapid, one-step immunoaffinity approach to quantify HCC exosomes directly from a small serum volume.

Methods

HCC-derived exosomes in the serum were captured using fluorescent phycoerythrin (PE)-conjugated antibodies targeted to GPC3 and alpha-fetoprotein (AFP). Total and HCC-specific exosomes were then quantified in culture supernatant or patient-derived serums using fluorescence nanoparticle tracking analysis (F-NTA). The performance of HCC exosome quantification in the serum was compared with the tumor size determined by MRI.

Results

Initially we tested the detection limits of the F-NTA using synthetic fluorescent and non-fluorescent beads. The assay showed an acceptable sensitivity with a detection range of 104-108 particles/mL. Additionally, the combination of immunocapture followed by size-exclusion column purification allows the isolation of smaller-size EVs and quantification by F-NTA. Our assay demonstrated that HCC cell culture releases a significantly higher quantity of GPC3 or GPC3+AFP positive EVs (100-200 particles/cell) compared to non-HCC culture (10-40 particles/cell) (p<0.01 and p<0.05 respectively). The F-NTA enables absolute counting of HCC-specific exosomes in the clinical samples with preserved biological immunoreactivity. The performance of F-NTA was clinically validated in serum from patients ± cirrhosis and with confirmed HCC. F-NTA quantification data show selective enrichment of AFP and GPC3 positive EVs in HCC serum compared to malignancy-free cirrhosis (AUC values for GPC3, AFP, and GPC3/AFP were found 0.79, 0.71, and 0.72 respectively). The MRI-confirmed patient cohort indicated that there was a positive correlation between total tumor size and GPC3-positive exosome concentration (r:0.78 and p<0.001).

Conclusion

We developed an immunocapture assay that can be used for simultaneous isolation and quantification of HCC-derived exosomes from a small serum volume with high accuracy.

Effects of toxicants on endoplasmic reticulum stress and hepatic cell fate determination

Toxicant-induced injury is a significant global health issue. However, the mechanisms through which toxicants such as carbon tetrachloride, acetaminophen, dimethylformamide, cocaine, and morphine induce the death of multiple cell types and contribute to liver toxicity are highly complex. This phenomenon involves intricate signaling pathways in association with oxidative stress, inflammation, and activation of death receptors, which are closely linked to endoplasmic reticulum (ER) stress. ER stress initially triggers the unfolded protein response, which either promotes cell survival or causes cell death at later times, depending on the severity and duration of the stress. Thus, comprehending the molecular basis governing cell fate determination in the context of ER stress may provide key insights into the prevention and treatment of toxicant-induced injury. This review summarizes our current understanding of agents that trigger different forms of ER stress-mediated cell death, necroptosis, ferroptosis, pyroptosis, and apoptosis, and covers the underlying molecular basis of toxicant-induced ER stress, as well as potential target molecules.

Acute Exposure to Microplastics Induced Changes in Behavior and Inflammation in Young and Old Mice

Environmental pollutants have become quite ubiquitous over the past two centuries; of those, plastics, and in particular, microplastics (<5 mm), are among the most pervasive pollutants. Microplastics (MPs) have found their way into the air, water system, and food chain and are either purposely produced or are derived from the breakdown of larger plastic materials. Despite the societal advancements that plastics have allowed, the mismanagement of plastic waste has become a pressing global issue. Pioneering studies on MPs toxicity have shown that exposure to MPs induces oxidative stress, inflammation, and decreased cell viability in marine organisms. Current research suggests that these MPs are transported throughout the environment and can accumulate in human tissues; however, research on the health effects of MPs, especially in mammals, is still very limited. This has led our group to explore the biological and cognitive consequences of exposure to MPs in a rodent model. Following a three-week exposure to water treated with fluorescently-labeled pristine polystyrene MPs, young and old C57BL/6J mice were assessed using behavioral assays, such as open-field and light-dark preference, followed by tissue analyses using fluorescent immunohistochemistry, Western blot, and qPCR. Data from these assays suggest that short-term exposure to MPs induces both behavioral changes as well as alterations in immune markers in liver and brain tissues. Additionally, we noted that these changes differed depending on age, indicating a possible age-dependent effect. These findings suggest the need for further research to better understand the mechanisms by which microplastics may induce physiological and cognitive changes.

An Evaluation of the Cytotoxic and Genotoxic Effects of the Marine Toxin C17-SAMT in Human TK6 and HepaRG Cell Lines

This study investigates the genotoxicity and cytotoxicity of C17-sphinganine analog mycotoxin (C17-SAMT) using in vitro assays. C17-SAMT was previously identified as the cause of unusual toxicity in cultured mussels from the Bizerte Lagoon in northern Tunisia. While a previous in vivo genotoxicity study was inconclusive, in vitro results demonstrated that C17-SAMT induced an increase in micronucleus formation in human lymphoblastoid TK6 cells at concentrations of 0.87 µM and 1.74 µM. In addition, multiparametric cytotoxicity assays were performed in the human hepatoma HepaRG cell line, which showed that C17-SAMT induced mitochondrial dysfunction, decreased cellular ATP levels, and altered the expression of various proteins, including superoxide dismutase SOD2, heme oxygenase HO-1, and NF-κB. These results suggest that C17-SAMT is mutagenic in vitro and can induce mitochondrial dysfunction in HepaRG cells. However, the exact mode of action of this toxin requires further investigation. Overall, this study highlights the potential toxicity of C17-SAMT and the need for further research to better understand its effects.