Methylparaben induces hepatic glycolipid metabolism disorder by activating the IRE1α-XBP1 signaling pathway in male mice

Parabens exposure and its impact on diabesity: A review

Parabens are a family of alkyl esters of 4-hydroxybenzoic acid. The most commonly used include methylparaben, ethylparaben, propylparaben, and butylparaben. These compounds have been reported to disrupt the endocrine system and are believed to affect the central nervous, immune, and reproductive systems, as well as lipid homeostasis, glucose levels, and thyroid function. Given these effects, parabens pose potential health risks, including their possible link to conditions like diabesity - a term describing the dual condition of type 2 diabetes mellitus and obesity. This review explores current literature on how parabens may influence key mechanisms in diabesity, such as gluconeogenesis, glycogenolysis, adipogenesis, insulin resistance, and inflammation. Understanding their role in these metabolic pathways is critical for assessing their contribution to the diabesity epidemic and guiding future research for minimizing their harmful health impacts.

Exposure profiles, determinants, and health risks of chemicals in personal care products among healthy older adults from the China BAPE study

Personal care products (PCPs) are ubiquitously present in the environment, and the associated health risks have been increasingly concerned worldwide. However, knowledge regarding exposure assessments of older adults to these chemicals and their health risks remains largely limited. In the present study, five repeated surveys involving 76 healthy older adults in Jinan, Shandong Province, were performed to quantify urinary exposure levels of 14 chemicals in PCPs. Moreover, influencing factors and health risks associated with exposure to these chemicals were thoroughly analyzed. Our findings revealed that methyl paraben (MeP) was the predominant chemical in PCP in the urine of the elderly, with a median concentration of 16.17 μg/L. Dietary intake, particularly fish and milk products, along with exposure to ambient PM2.5, were identified as the primary sources of certain chemicals in PCPs. Additionally, an increased physical activity was associated with decreased concentrations of benzophenone-2 (BP-2) within the body. Risk assessment demonstrated that chemicals in PCPs currently posed minimal health risks to the elderly. Our findings provide substantial references for mitigating the health risks of these chemical exposures in healthy older adults, ultimately safeguarding their overall and physical well-being.

Magnolol protects C6 glioma cells against neurotoxicity of FB1 via modulating PI3K/Akt and mitochondria-associated apoptosis signaling pathways

Fumonisin B1 (FB1) is a contaminant commonly occurring in crops and food. Mycotoxin contamination, including FB1, has been progressively shown to be an important risk factor in mediating neurotoxicity and neurodegenerative diseases. Studies have found that magnolol (MAG) exhibits favorable pharmacological effects in the central nervous system. However, the protective effects of MAG against FB1-induced neurotoxicity and the molecular pathways involved have not been fully elucidated. Our study aimed to investigate the neuroprotective effects of MAG on FB1-exposed C6 cells and to identify the underlying mechanisms. A model of FB1-induced cytotoxicity in C6 glial cells was established. C6 cells were treated with MAG (40, 80 and 160 μM) in the presence/absence of FB1 (15 μM) and then assessed for cell viability, cellular and mitochondrial morphology and oxidative stress. The mechanism of action of MAG was revealed using a variety of means including RNA-seq, qRT-PCR, Western blot, immunofluorescence, scanning electron microscopy analysis and agonist validation experiments. Our results indicated that MAG significantly alleviated AFB1-induced C6 astroglial cytotoxicity, as evidenced by elevated cell viability and restoration of overall cellular and mitochondrial morphology. Meanwhile, MAG also alleviated oxidative stress in FB1-exposed C6 cells, with 80 μM MAG showing the best effect. Transcriptome analysis showed that PI3K/Akt and apoptosis involved in it might be the key pathway for MAG to treat FB1 neurotoxicity. MAG suppressed FB1-induced mitochondria-dependent apoptosis in C6 cells, primarily manifested by reduced apoptosis rate and reversal of apoptosis-associated protein expression. It was verified that MAG restored the expression of p-PI3K and p-Akt in FB1-treated cells and reversed the downstream effectors IKKα and NF-κB via measurement of related protein levels. The rescue experiment using Akt pathway activator (SC79) was further confirmed that activation of the PI3K/Akt signaling pathway is an effective strategy for MAG to mitigate FB1-induced cytotoxicity in C6 astroglial cells.

Endocrine-disrupting chemical, methylparaben, in environmentally relevant exposure promotes hazardous effects on the hypothalamus-pituitary-thyroid axis

Methylparaben (MP) belongs to the paraben class and is widely used as a preservative in personal care products, medicines, and some foods. MP acts as an endocrine disrupting chemical (EDC) on the hypothalamic-pituitary-thyroid (HPT) axis. However, the effects of MP have not yet been completely elucidated, as published results are scarce and controversial. The objective of this work was to evaluate the effects of subacute exposure to MP on the HPT axis of male rats. To achieve this, in this study the animals were divided into four experimental groups: control, MP3, MP30 and MP300 (3, 30 and 300 μg/kg/day, respectively). The rats were gavage for 14 days and sacrificed at the end of MP treatment. Our findings demonstrated that MP can promote important changes in thyroid morphology, including a decrease in follicular area, colloid area, epithelial area, and epithelial height, affecting the homeostasis of the HPT axis, and affecting the expression of genes related to hormonal biosynthesis. Furthermore, changes in interstitial collagen deposition were also demonstrated. Finally, we conclude that exposure to MP can be harmful to health, as it is involved in the dysregulation of the thyroid gland, affecting its morphophysiology, suggesting that even doses considered safe by current legislation can be dangerous and should be reconsidered.

Cadmium-Induced Kidney Apoptosis Based on the IRE1α-XBP1 Signaling Pathway and the Protective Effect of Quercetin

Cadmium (Cd) is an important environmental pollutant that can enter the body and inflict kidney damage. Quercetin (Que) is a natural flavonoid compound that can alleviate kidney damage in Cd-treated rats, but the specific mechanism is unclear. Herein, 24 male Sprague-Dawley rats were divided into four groups, namely the control, Cd, Cd + Que, and Que groups. Four weeks later, the rats were anesthetized with ether and were euthanized; then, their blood was collected and their kidneys were removed. Renal function markers were measured. Kidney tissue structure was observed by HE staining, cell apoptosis was detected by the TUNEL method, and mRNA and protein expression levels in the IRE1α-XBP1 apoptosis signaling pathway were analyzed by RT-PCR and Western blotting. Results showed that the Cd treatment group exhibited decreased renal dysfunction and pathologic injury. Cd-induced tissue damage and cell apoptosis and significantly increased the mRNA and protein expression levels (p < 0.01) related to the IRE1α-XBP1 signaling pathway. Compared with the Cd group, the Cd + Que group exhibited increased renal dysfunction. Conversely, kidney tissue damage and renal cell apoptosis decreased, and the mRNA and protein expression levels of IRE1α and XBP1 significantly decreased (p < 0.01). Cd treatment inflicted renal damage. Therefore, Que can restore the kidney tissue damage and alleviate the cell apoptosis caused by Cd through the inhibition of the IRE1α-XBP1 signaling pathway.

Propylparaben-induced endoplasmic reticulum stress triggers G2/M phase cell cycle arrest and initiates caspase-3-dependent apoptosis in human lung cells

BACKGROUND

Propylparaben (PrP) is commonly used as an antimicrobial agent in food, cosmetics, and pharmaceuticals. While recent studies have shown that PrP exposure can cause various disruptions in cellular physiology, the precise mechanisms behind these effects remain unclear.

OBJECTIVE

In this study, we sought to examine the cytotoxic effects of PrP exposure on human lung cells in a dose- and time-dependent manner. We utilized flow cytometry to analyze the expression of proteins associated with the cell cycle and apoptosis at the single-cell level.

RESULTS

Our results showed that PrP treatment leads to a significant upregulation of genes related to ER stress. The activation of ER stress results in a decrease in cyclin B1 levels, which subsequently causes cell cycle arrest at the G2/M phase. After 48 h of PrP exposure, the unfolded protein response (UPR) triggers an apoptotic signaling pathway, increasing the number of cells undergoing caspase-3-mediated apoptosis. Together, these physiological changes lead to a reduction in cell viability in the presence of PrP.

CONCLUSION

These findings suggest that PrP exerts harmful effects on human lung cells by activating ER stress, which can lead to apoptosis and cell cycle arrest.

Profiling metabolites and exploring metabolism of parabens in human urine using non-target screening and molecular networking

Parabens are widely used as preservatives in food, pharmaceuticals, and cosmetics due to their excellent antimicrobial activities, cost-effectiveness, and stability. Previous studies have demonstrated their harmful potential and ubiquity in the environment and human tissues. This study revealed profiles of parabens and their metabolites in urine samples from a general population of different ages in China using non-target screening. Metabolism of parabens in human bodies was further explored through the identified metabolites in combination of molecular networking. A total of 34 paraben compounds were screened in the urine samples. In addition to 3 identified confidence level 1 (CL1) parent parabens, 3 CL2 compounds were also identified, namely 4-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid, and ethylparaben sulfate. Furthermore, 6 CL3 compounds were tentatively identified, five of which were sulfonated and sulfated metabolites of parabens. The remaining 22 were CL4 features without certain chemical structures. Hazardousness assessment suggested toxic potential of the identified metabolites. Distribution of the parabens and metabolites in the urines showed age-dependent differences. Sulfonation and sulfation were potentially significant metabolic pathways of the parabens in human bodies. This study provides a new insight into understanding metabolism of parabens in human bodies and potential risks of human exposure to parabens.

Targeting endoplasmic reticulum stress-induced lymphatic dysfunction for mitigating bisphosphonate-related osteonecrosis

BACKGROUND

Bisphosphonates (BPs) are the first-line treatment to stop bone resorption in diseases, including osteoporosis, Paget's disease, multiple myeloma and bone metastases of cancer. However, BPs-related osteonecrosis of the jaw (BRONJ), characterized by local inflammation and jawbone necrosis, is a severe intractable complication. The cumulative inflammatory burden often accompanies impaired lymphatic drainage, but its specific impact on BRONJ and the underlying mechanisms remain unclear.

METHODS

The mouse BRONJ model was established to assess the integrity and drainage function of lymphatic vessels by tissue clearing techniques, injected indocyanine green lymphatic clearance assay, flow cytometry analysis and histopathological staining. RNA sequencing, metabolome analysis, transmission electron microscopy and Western blotting were utilized to analyze the impacts of Zoledronate acid (ZA) on endoplasmic reticulum stress (ERS) and function of lymphatic endothelial cells (LECs). By constructing Lyve1creERT; SIRT6f/f and Lyve1creERT; ATG5f/f mice, we evaluated the role of ERS-induced LECs apoptosis in the progression of BRONJ. Additionally, we developed a nanoparticle-loaded ZA and rapamycin (ZDPR) to enhance autophagy and evaluated its potential in mitigating BRONJ.

RESULTS

The mouse BRONJ model displayed impaired lymphatic drainage, accompanied by significant local inflammation and bone necrosis. The prolonged stimulation of ZA resulted in the extension of ERS and the inhibition of autophagy in LECs, ultimately leading to apoptosis. Mechanistically, ZA activated XBP1s through the NAD+/SIRT6 pathway, initiating ERS-induced apoptosis in LECs. The conditional knockout mouse models demonstrated that the deletion of SIRT6 or ATG5 significantly worsened lymphatic drainage and inflammatory infiltration in BRONJ. Additionally, the innovative nanoparticle ZDPR alleviated ERS-apoptosis in LECs and enhanced lymphatic function, facilitating inflammation resolution.

CONCLUSION

Our study has elucidated the role of the NAD+/SIRT6/XBP1s pathway in ERS-induced apoptosis in ZA-treated LECs, and further confirmed the therapeutic potential of ZDPR in restoring endothelial function and improving lymphatic drainage, thereby effectively mitigating BRONJ.

KEY POINTS

Bisphosphonate-induced lymphatic drainage impairment exacerbates bone necrosis. Zoledronate acid triggers endoplasmic reticulum stress and apoptosis in lymphatic endothelial cells via the NAD+/SIRT6/XBP1s pathway. Novel nanoparticle-loaded Zoledronate acid and rapamycin enhances autophagy, restores lymphatic function, and mitigates bisphosphonates-related osteonecrosis of the jaw progression.

A new perspective on liver diseases: Focusing on the mitochondria-associated endoplasmic reticulum membranes

The pathogenesis of liver diseases is multifaceted and intricate, posing a persistent global public health challenge with limited therapeutic options. Therefore, further research into liver diseases is imperative for better comprehension and advancement in treatment strategies. Numerous studies have confirmed the endoplasmic reticulum (ER) and mitochondria as key organelles driving liver diseases. Notably, the mitochondrial-associated ER membranes (MAMs) establish a physical and functional connection between the ER and mitochondria, highlighting the importance of inter-organelle communication in maintaining their functional homeostasis. This review delves into the intricate architecture and regulative mechanism of the integrated MAM that facilitate the physiological transfer of signals and substances between organelles. Additionally, we also provide a detailed overview regarding the varied pathogenic roles of malfunctioning MAM in liver diseases, focusing on its involvement in the progression of ER stress and mitochondrial dysfunction, the regulation of mitochondrial dynamics and Ca2+ transfer, as well as the disruption of lipid and glucose homeostasis. Furthermore, the current challenges and prospects associated with MAM in liver disease research are thoroughly discussed. In conclusion, elucidating the specific structure and function of MAM in different liver diseases may pave the way for novel therapeutic strategies.