High-fat diet exacerbated decabromodiphenyl ether-induced hepatocyte apoptosis via intensifying the transfer of Ca2+ from endoplasmic reticulum to mitochondria

Quantitative imaging using [18F]F-TZ3108 to assess metabolic-associated fatty liver disease progression and low-carbohydrate diet efficacy

OBJECTIVE

The Sigma-1 receptor (Sig-1R), located in the mitochondrion-associated membranes (MAMs), is an important biomarker for endoplasmic reticulum (ER) stress and plays a crucial role in the advancement of metabolic-associated fatty liver disease (MAFLD). Despite its significance, current methods to monitor MAFLD progression and treatment response are limited. This study aims to address this gap by utilizing [18F]F-TZ3108, an effecient tracer targeting Sig-1R, to quantitatively assess MAFLD progression and the efficacy of a low-carbohydrate diet (LCD) as a potential therapeutic intervention.

METHODS

The C57 BL/6 J mice were fed either a high-fat diet (HFD) or regular diet (CTR) for 12 weeks, and the progression of MAFLD was continuously monitored at 0, 4, 8, 12 weeks via [18F]F-TZ3108 positron emission tomography/computed tomography (PET/CT) and ex vivo assessment. After confirming successful induction, LDC intervention was administered in the HFD group for 2 weeks. And relevant post-treatment evaluations were also performed.

RESULTS

PET/CT revealed a continuous decline in the hepatic binding potential (BPND) of [18F]F-TZ3108 in mice in the HFD group during the induction period, when compared with the BPND in the CTR group. This reduction was significant after the 4th week of induction (p < 0.05). Furthermore, following intervention with LCD, there was a significant improvement in BPND (LCD vs HFD, p = 0.001).

CONCLUSIONS

The results of this study demonstrate that LCD therapy effectively mitigates MAFLD progression. Furthermore, the use of PET imaging with [18F]F-TZ3108 provides a reliable, non-invasive method for monitoring the progression and treatment response of MAFLD, offering significant potential for early detection and personalized treatment evaluation.

Lower-dose vs high-dose oral bisphenol S action of lipid metabolism in liver of male SD rat via mediating different SREBP isoforms

Bisphenol S (BPS) is commonly used for the industrial production of thermal paper, polycarbonate plastics, epoxy resins and other materials. Studies have reported that BPS can lead to triglyceride (TAG) or/and cholesterol (CHO) accumulation in the liver in zebrafish and mice, but the reasons for the different types of lipids that accumulate in the liver following BPS exposure are unclear. Here, the influences of lower-dose (10 mg/kg body weight/day) and high-dose (50 mg/kg body weight/day) BPS exposure to male SD rats on the accumulation of different lipids in the liver were explored. The results indicated that BPS treatment increased the levels of acetyl-CoA and glycogen in the liver. A lower dose of BPS upregulated the mRNA and protein expression levels of sterol regulatory element-binding protein 1 (srebp1), which is involved in the de novo synthesis of TAG in the liver, thus promoting the synthesis of glycerides (diacetylglyceride and TAG). However, a higher dose of BPS induced CHO accumulation, but inhibited the mRNA expression of genes (i.e., srebp2, hmgcr and hmgcs) involved in the de novo synthesis of CHO in the liver. Excessive accumulation of glycerides and CHO led to destruction of the physiological structure of rat liver, causing disorders in liver function. Our data provide new insight into the different mechanisms by which glyceride and CHO accumulate in the liver after BPS exposure.

Association between dietary exposure to chemical contaminants and risk of dementia in older persons

BACKGROUND

Diet is a major route of exposure to potentially neurotoxic chemicals, yet the epidemiological association of diet contaminants with dementia is unknown. We studied the link between dietary exposure to multiple chemicals and dementia risk in older persons, considering interaction with dietary fat content, which may modify the bioavailability and toxicity of (lipophilic) chemicals.

METHODS

We included 1,288 non-demented participants from the French Three-City cohort who answered a food frequency questionnaire and 24-hour recall at baseline and were followed for incident dementia. Dietary exposure to 167 contaminants was assessed by combining food intakes with food chemical content from the French second Total Diet Study. We assessed the relation of each individual contaminant with dementia risk using multivariable-adjusted Cox models, exploring effect modification by high-fat diet (>35 % energy from fat). Among high-fat diet consumers, we looked for a signature of contaminants associated with dementia using elastic-net penalization and assess their joint effect.

RESULTS

Participants were 76 years-old on average at baseline and 62 % were women. In total, 314 individuals developed dementia over a median 10 years. No contaminant was associated with dementia in the whole population. However, having a high-fat diet was a strong effect modifier for 85 contaminants (FDR-corrected p < 0.05 for interactions) in single-chemical analyses, so that higher intakes were significantly associated with higher dementia risk among high-fat consumers only (n = 386). Among them, a multi-chemical approach revealed a signature of 9 contaminants related to dementia, including 4 perfluoroalkyl substances, 2 flame retardants hexabromocyclododecane (HBCDD) congeners, 2 mycotoxins, and nitrites. This selection included two top hits from the single-chemical analyses (α-HBCDD and perfluorooctanesulfonic acid [PFOS]), and was mainly provided by delicatessen meat, seafood and bread/crispbread.

CONCLUSION

In this large population-based study, dietary exposure to several chemicals was associated with higher dementia risk among older persons consuming > 35 % energy from fat in diet.

Spatial mapping of hepatic ER and mitochondria architecture reveals zonated remodeling in fasting and obesity

The hepatocytes within the liver present an immense capacity to adapt to changes in nutrient availability. Here, by using high resolution volume electron microscopy, we map how hepatic subcellular spatial organization is regulated during nutritional fluctuations and as a function of liver zonation. We identify that fasting leads to remodeling of endoplasmic reticulum (ER) architecture in hepatocytes, characterized by the induction of single rough ER sheet around the mitochondria, which becomes larger and flatter. These alterations are enriched in periportal and mid-lobular hepatocytes but not in pericentral hepatocytes. Gain- and loss-of-function in vivo models demonstrate that the Ribosome receptor binding protein1 (RRBP1) is required to enable fasting-induced ER sheet-mitochondria interactions and to regulate hepatic fatty acid oxidation. Endogenous RRBP1 is enriched around periportal and mid-lobular regions of the liver. In obesity, ER-mitochondria interactions are distinct and fasting fails to induce rough ER sheet-mitochondrion interactions. These findings illustrate the importance of a regulated molecular architecture for hepatocyte metabolic flexibility.

Effect of brominated flame retardants exposure on liver function and the risk of non-alcoholic fatty liver disease in the US population

BACKGROUND

The relationship between brominated flame retardants (BFRs) exposure and the human liver was still not well understood.

METHODS

A total of 3108 participants (age > 12) from the National Health and Nutrition Examination Survey (NHANES) database spanning from 2005 to 2016 were included as the study population, with nine BFRs exhibiting a detection rate of over 70% serving as the exposure factor. The singular effects and combined effects of BFRs exposure on liver injury, non-alcoholic fatty liver disease (NAFLD), and advanced hepatic fibrosis (AHF) were evaluated separately. Finally, COX regression was employed to explore the hazard ratios associated with individual BFRs.

RESULTS

In our analysis of individual exposures, we found significant positive association of PBB153 with alanine aminotransferase (ALT), PBB153 with aspartate aminotransferase (AST), PBDE47, PBDE85, PBDE99, PBDE100, and PBDE154 with alkaline phosphatase (ALP), PBDE28 and PBB153 with gamma-glutamyl transaminase (GGT), PBB153 with the risk of NAFLD and AHF; and significant negative association of PBB153 with ALP, PBDE28, PBDE47, PBDE99, PBDE100, PBDE85, PBDE209, and PBDE154 with albumin (ALB), PBB153 with AST/ALT. The nonlinear analysis results from Restricted Cubic Spline (RCS) further validated these associations (all P<0.05). In the mixed analysis combining Weighted Quantile Sum (WQS) regression and Quantile G-computation (QGC) analysis, BFRs were positively associated with ALT (β>0, P<0.001), GGT (β>0, P<0.001), and the risk of NAFLD (OR>1, P=0.007). Conversely, BFRs exhibited significant negative correlations with ALP (β<0, P<0.001), ALB (β<0, P<0.001), and AST/ALT (β<0, P<0.001). Furthermore, the COX regression analysis revealed that PBB153 had the highest hazard ratio among the BFRs.

CONCLUSIONS

BFR exposure may increase the risk of liver injury and NAFLD, with no significant association with AHF risk. The impact of BFR exposure on liver health should not be overlooked, especially in individuals residing in impoverished areas.

A critical review on BDE-209: Source, distribution, influencing factors, toxicity, and degradation

As the most widely used polybrominated diphenyl ether, BDE-209 is commonly used in polymer-based commercial and household products. Due to its unique physicochemical properties, BDE-209 is ubiquitous in a variety of environmental compartments and can be exposed to organisms in various ways and cause toxic effects. The present review outlines the current state of knowledge on the occurrence of BDE-209 in the environment, influencing factors, toxicity, and degradation. BDE-209 has been detected in various environmental matrices including air, soil, water, and sediment. Additionally, environmental factors such as organic matter, total suspended particulate, hydrodynamic, wind, and temperature affecting BDE-209 are specifically discussed. Toxicity studies suggest BDE-209 may cause systemic toxic effects on living organisms, reproductive toxicity, embryo-fetal toxicity, genetic toxicity, endocrine toxicity, neurotoxicity, immunotoxicity, and developmental toxicity, or even be carcinogenic. BDE-209 has toxic effects on organisms mainly through epigenetic regulation and induction of oxidative stress. Evidence regarding the degradation of BDE-209, including biodegradation, photodegradation, Fenton degradation, zero-valent iron degradation, chemical oxidative degradation, and microwave radiation degradation is summarized. This review may contribute to assessing the environmental risks of BDE-209 to help develop rational management plans.

Selenoprotein K knockdown induces apoptosis in skeletal muscle satellite cells via calcium dyshomeostasis-mediated endoplasmic reticulum stress

Skeletal muscle satellite cells (SMSCs), known as muscle stem cells, play an important role in muscle embryonic development, post-birth growth, and regeneration after injury. Selenoprotein K (SELENOK), an endoplasmic reticulum (ER) resident selenoprotein, is known to regulate calcium ion (Ca2+) flux and ER stress (ERS). SELENOK deficiency is involved in dietary selenium deficiency-induced muscle injury, but the regulatory mechanisms of SELENOK in SMSCs development remain poorly explored in chicken. Here, we established a SELENOK deficient model to explore the role of SELENOK in SMSCs. SELENOK knockdown inhibited SMSCs proliferation and differentiation by regulating the protein levels of paired box 7 (Pax7), myogenic factor 5 (Myf5), CyclinD1, myogenic differentiation (MyoD), and Myf6. Further analysis exhibited that SELENOK knockdown markedly activated the ERS signaling pathways, which ultimately induced apoptosis in SMSCs. SELENOK knockdown-induced ERS is related with ER Ca2+ ([Ca2+]ER) overload via decreasing the protein levels of STIM2, Orai1, palmitoylation of inositol 1,4,5-trisphosphate receptor 1 (IP3R1), phospholamban (PLN), and plasma membrane Ca2+-ATPase (PMCA) while increasing the protein levels of sarco/endoplasmic Ca2+-ATPase 1 (SERCA1) and Na+/Ca2+ exchanger 1 (NCX1). Moreover, thimerosal, an activator of IP3R1, reversed the overload of [Ca2+]ER, ERS, and subsequent apoptosis caused by SELENOK knockdown. These findings indicated that SELENOK knockdown triggered ERS driven by intracellular Ca2+ dyshomeostasis and further induced apoptosis, which ultimately inhibited SMSCs proliferation and differentiation.

A meta-analysis of randomized controlled studies on the hepatoxicity induced by polybrominated diphenyl ethers (PBDEs) in rats and mice

Several toxicological studies were conducted to evaluate the hepatoxicity of PBDEs using different animal models, congeners, duration of exposure, and other parameters. These variations in different animal models and conditions might have an impact on extrapolating experimental results to humans. Hence, by the meta-analysis, we aimed to clarify and elucidate the species differences in hepatoxicity induced by PBDE exposure in rats and mice across different conditions and moderators. Fourteen in vivo studies that utilized rats and mice models were identified, and data such as author names, year of publication, type of PBDE congeners, rodent species, life stage of exposure, dosage, duration, and hepatoxicity indicators were extracted. The pooled standard mean difference (SMD) with a 95% confidence interval (95% CI) was used to evaluate the association between hepatoxicity and PBDE exposure across multiple approaches of measurement. Subgroup analysis, meta-regression, and interaction analysis were utilized to elucidate the species-related differences among the results of the involved studies. The pooled SMD of hepatoxicity of PBDE exposure in the involved in vivo studies was 1.82 (p = 0.016), indicating exposure to PBDE congeners and mixtures is associated with a significant increase in liver toxicity in rodents. Moreover, findings showed that rats were more sensitive to PBDEs than mice with the BDE-209 had the highest SMD value. Among the life stages of exposure, embryonic stage was found to be the most sensitive to hepatoxicity induced by PBDE congeners. Positive relationships were found between the incidence of hepatoxicity with dosage and duration of exposure to PBDE. Interaction analyses showed significant interactions between rodent species (rats or mice), dosage, length of exposure, and hepatotoxicity endpoints. Rats demonstrated an increased susceptibility to variations in organ weight, histopathological changes, mitochondrial dysfunction, and oxidative stress markers. Conversely, mice showed pronounced lipid accumulation and modifications in liver enzyme expression levels. However, significant differences were not found in terms of endoplasmic reticular stress as a mechanistic endpoint for hepatotoxicity. In conclusion, this meta-analysis showed that there might be some species-related differences in hepatoxicity induced by PBDE exposure in rats and mice depending on the parameters used. This study highlights the importance of cross-species extrapolation of results from animal models to accurately assess the potential risks to human health from exposure to PBDEs.

Hepatotoxicity evaluation and possible mechanisms of decabrominated diphenyl ethers (BDE-209) in broilers: Oxidative stress, inflammatory, and transcriptomics

Decabrominated diphenyl ether (BDE-209), a persistent organic pollutant, is linked to a great number of health problems, the most severe of which impact the liver due to its role in the elimination and degradation of exogenous harmful substances. Though the hepatotoxicity of BDE-209 has been observed, its underlying mechanism is yet unknown. The purpose of this study is to thoroughly investigate the hepatotoxicity of BDE-209 and its molecular processes in broilers by subjecting 120 male broilers to varied concentrations of BDE-209 for 42 days. We observed that the bioaccumulation of BDE-209 in the liver in a dose-dependent manner, and that BDE-209 exposure can raise the concentrations of ALT, AST, and GGT, accompanied by hepatocyte fatty degeneration and inflammatory foci. In the hepatic homogenates, oxidative stress was evidenced by elevated levels of MDA and ROS and decreased activies of SOD and CAT. Additionally, pro-inflammatory cytokines including IL-1, IL-1β, TNF-α, IL-8 levels were increased, whereas anti-inflammatory cytokine IL-4 level was declined. Furthermore, RNA sequencing revealed that genes involved in inflammation were considerably dysregulated, and real-time PCR verified the expressed alterations of numerous genes related to the MAPK and WNT signaling pathways. The protein concentrations of NF-κB, β-catenin, and WNT5A, and the phosphorylation levels of JNK and ERK were all dramatically enhanced. The current study indicates that BDE-209 exposure can cause hepatotoxicity in broilers via bioaccumulation and oxidative stress, which then activates the MAPK and WNT signaling pathways, subsequently generating inflammation and hepatic injury.

Aerobic Degradation Characteristics and Mechanism of Decabromodiphenyl Ether (BDE-209) Using Complex Bacteria Communities

Complex bacteria communities that comprised Brevibacillus sp. (M1) and Achromobacter sp. (M2) with effective abilities of degrading decabromodiphenyl ether (BDE-209) were investigated for their degradation characteristics and mechanisms under aerobic conditions. The experimental results indicated that 88.4% of 10 mg L^-1 BDE-209 could be degraded after incubation for 120 h under the optimum conditions of pH 7.0, 30 °C and 15% of the inoculation volume, and the addition ratio of two bacterial suspensions was 1:1. Based on the identification of BDE-209 degradation products via liquid chromatography-mass spectrometry (LC-MS) analysis, the biodegradation pathway of BDE-209 was proposed. The debromination, hydroxylation, deprotonation, breakage of ether bonds and ring-opening processes were included in the degradation process. Furthermore, intracellular enzymes had the greatest contribution to BDE-209 biodegradation, and the inhibition of piperyl butoxide (PB) for BDE-209 degradation revealed that the cytochrome P450 (CYP) enzyme was likely the key enzyme during BDE-209 degradation by bacteria M (1+2). Our study provided alternative ideas for the microbial degradation of BDE-209 by aerobic complex bacteria communities in a water system.

Metabolism toxicity and susceptibility of decabromodiphenyl ether (BDE-209) exposure on BRL cells with insulin resistance

Type 2 diabetes mellitus (T2DM) is a metabolic disease characterized by insulin resistance (IR) and has attracted worldwide attention due to its high prevalence. As a typical persistent organic pollutant, decabromodiphenyl ether (BDE-209) has been detected in food and human samples, and the concentration trends increase year by year. In addition, it has been proved to have the potential to increase the risk of IR, but it is rarely reported whether it could aggravate IR in T2DM. Therefore, in this study, the IR-BRL (buffalo rat liver cells with IR) model was applied to study the metabolism toxicity and susceptibility of BDE-209. Results showed that BDE-209 could inhibit glucose absorption and increase the levels of serum total cholesterol (TC) and triglyceride (TG), ultimately leading to the disorder of glucolipid metabolism in IR-BRL cells. Besides, it also could cause cell damage by increasing the levels of aspartate transaminase (AST), alanine aminotransferase (ALT), and malondialdehyde (MDA) in cells. Moreover, its potential mechanisms were to: (1) affect the transport of glucose, synthesis of glycogen and fatty acid via IRS-1/GLUT4 and IRS-1/PI3K/AKT/GSK-3β pathways; (2) impact the proliferation and differentiation by regulating the expression of Mek1/2, Erk1/2, and mTOR proteins and genes. Furthermore, susceptibility analysis showed that there was a significant synergism interaction between IR and BDE-209, which suggested that IR-BRL cells were more susceptible to the metabolism toxicity induced by BDE-209.