Hyperphosphorylation of EGFR/ERK signaling facilitates long-term arsenite-induced hepatocytes epithelial-mesenchymal transition and liver fibrosis in sprague-dawley rats

Role of the USP7/FOXO3A axis in environmentally relevant doses of arsenic-induced lung carcinogenesis: Insights from bioinformatics analysis and model of human epithelial cell malignant transformation

Arsenic (As) is classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC). Exposure to As has been associated with an increased risk of various cancers, particularly lung cancer. However, the precise molecular mechanisms contributing to this carcinogenesis are not well understood. In our study, we analyzed transcriptomic data from the GEO database (GSE36684), identifying 764 differentially expressed genes (DEGs) in BEAS-2B cells treated with environmentally relevant doses of As for 8 weeks. A KEGG pathway enrichment analysis suggested that the FoxO pathway activation might be a novel key signaling event in As-induced carcinogenesis. We further analyzed the expression of 11 DEGs involved in the FoxO pathway using the TCGA-LUSC dataset. The findings revealed that four genes displayed expression patterns in tumor tissues consistent with those observed after As treatment in GEO dataset. Among them, USP7 was upregulated, while ATM, S1PR1, and PLK2 were downregulated in cancer tissues. High USP7 expression was specifically linked to a poor prognosis in lung squamous cell carcinoma (LUSC). To explore the role of USP7 in As-induced malignant transformation, BEAS-2B cells were exposed to NaAsO2 concentrations of 0.2 μM and 2 μM for up to 20 weeks. Experimental results confirmed that NaAsO2 treatment suppressed the FoxO transcriptional activity by upregulating USP7 expression, subsequently downregulating ATM and PLK2 expression, which led to abnormalities in cell cycle regulation and apoptosis. Notably, knocking down USP7 in As-transformed cells resulted in significant reductions in cell proliferation, colony formation, and tumor formation ability in nude mice, indicating the USP7-regulated FOXO3A pathway could be central to As-induced lung carcinogenesis. Moreover, our research demonstrated that USP7 inhibited FOXO3A's ability to translocate from the cytoplasm to the nucleus by affecting its monoubiquitination status. Additionally, we speculated that As-induced the elevation of USP7 expression due to the excessive inflammatory cytokines secretion and the activation of mTORC1/WTAP pathway. These findings offer novel insights into the molecular mechanisms underlying As-mediated lung cancer.

Deciphering the Pharmacological Mechanism of Compound Purpura Decoction in Treating Henoch-Schonlein Purpura by Network Pharmacology, Molecular Docking and Experimental Validation

Henoch-Schonlein purpura (HSP) is an immunoglobulin A (IgA)-mediated systemic vasculitis that frequently develops in children and may progress to serious complications. Compound purpura decoction (CPD), a classical herbal combination, exerts favourable effects on the clinical symptoms and prognosis of HSP; however, the underlying molecular mechanism remains unclear. First, high-performance liquid chromatography analysis identified five bioactive components in CPD, including protocatechuic acid, chlorogenic acid, mangiferin, baicalin and buddleoside, with contents of 0.011 ± 0.02, 0.577 ± 0.33, 0.150 ± 0.05, 1.132 ± 0.23 and 0.369 ± 0.23 mg/g, respectively. Additionally, we established an animal model of allergic purpura to evaluate the therapeutic effects of CPD on HSP. CPD effectively alleviated renal and cutaneous vasculitis and reduced IgA deposition. CPD could regulate the Treg/Th17 cell balance, decrease the levels of the proinflammatory factors interleukin-6 and tumour necrosis factor-α, and suppress the expression of C3 and C5 (p < 0.05). Network pharmacology analysis suggested that the mechanism of CPD in HSP treatment mainly involved epidermal growth factor receptor (EGFR)-related targets and pathways, followed by molecular docking confirming strong binding affinity between EGFR and the bioactive components (binding energy< -4.25 kcal/mol). Real-time quantitative polymerase chain reaction and western blot showed that CPD suppressed the activation of the EGFR/extracellular signal-regulated kinase (ERK) signalling pathway (p < 0.05), which could be associated with the inhibition of complement system activation. This study provides a new perspective for understanding the pathogenesis and treatment of HSP.

Resveratrol Alleviates Arsenic Exposure-Induced Liver Fibrosis in Rats by Inhibiting Hepatocyte Senescence

Arsenic is an environmental pollutant that has garnered considerable attention from the World Health Organization. Liver fibrosis is an advanced pathological stage of liver injury that can be caused by chronic arsenic exposure and has the potential to be reversed to prevent cirrhosis and hepatic malignancies. However, effective treatment options are currently limited. Given the profibrogenic effect of hepatocyte senescence, we established a rat model of sub-chronic sodium arsenite exposure and investigated the ability of resveratrol (RSV), a potential anti-senescence agent, to ameliorate arsenic-induced liver fibrosis and elucidate the underlying mechanism from the perspective of hepatocyte senescence. The results demonstrated that RSV was capable of mitigating fibrosis phenotypes in rat livers, including the activation of hepatic stellate cell (HSC), the generation of extracellular matrix, and the deposition of collagen fibers in the liver vascular zone, which are all induced by arsenic exposure. Furthermore, as an activator of the longevity factor SIRT1, RSV antagonized the arsenic-induced inhibition of SIRT1 expression, thereby restoring the suppression of the senescence protein p16 by SIRT1. This prevented arsenic-induced hepatocyte senescence, manifesting as a decrease in telomere shortening and a reduction in the release of senescence-associated secretory phenotype (SASP)-related proteins. In conclusion, this study demonstrated that RSV counteracts arsenic-induced hepatocyte senescence and the release of SASP-related proteins by restoring the inhibitory effect of SIRT1 on p16, thereby suppressing the activation of fibrotic phenotypes and mitigating liver fibrosis. These findings provide new insights for understanding the mechanism of arsenic-induced liver fibrosis, and more importantly, they reveal novel potential interventional approaches.

PLIN5 contributes to lipophagy of hepatic stellate cells induced by inorganic arsenic

Arsenic exposure triggers the activation of hepatic stellate cells (HSCs), resulting in liver fibrosis (LF). A significant decrease in lipid droplets marks the activation of HSCs. However, the exact underlying molecular mechanism remains elusive. Lipophagy, a specialized form of selective autophagy, is crucial for the degradation of lipid droplets to maintain intracellular lipid metabolism homeostasis. In this study, arsenic treatment induced lipophagy, as evidenced by the co-localization of LC3 with lipid droplets. Remarkably, arsenic exposure increased the expression levels of Perilipin 5 (PLIN5), a lipid droplet-associated protein, both at the mRNA and protein levels. Moreover, silencing PLIN5 influenced arsenic-induced lipolysis. Consequently, the results of this study indicate that PLIN5 serves as a substrate protein involved in arsenic-induced lipophagy. This research offers a novel perspective on the mechanisms of arsenic-induced HSCs activation and liver lipid metabolism, potentially guiding new strategies for the prevention and treatment of arsenic-related liver diseases.

Prolonged exposure to NaAsO2 induces thyroid dysfunction and inflammatory injury in Sprague‒Dawley rats, involvement of NLRP3 inflammasome‒mediated pyroptosis

Arsenic, a well-known hazardous toxicant, has been found in recent years to act as an environmental endocrine disruptor that accumulates in various endocrine organs, impeding the normal physiological functions of these organs and altering hormone secretion levels. Moreover, some research has demonstrated a correlation between arsenic exposure and thyroid functions, suggesting that arsenic has a toxicological effect on the thyroid gland. However, the specific type of thyroid gland damage caused by arsenic exposure and its potential molecular mechanism remain poorly understood. In this study, the toxic effects of sodium arsenite (NaAsO2) exposure at different doses (0, 2.5, 5.0 and 10.0 mg/kg bw) and over different durations (12, 24 and 36 weeks) on thyroid tissue and thyroid hormone levels in Sprague‒Dawley (SD) rats were investigated, and the specific mechanisms underlying the effects were also explored. Our results showed that NaAsO2 exposure can cause accumulation of this element in the thyroid tissue of rats. More importantly, chronic exposure to NaAsO2 significantly upregulated the expression of NLRP3 inflammasome-related proteins in thyroid tissue, leading to pyroptosis of thyroid cells and subsequent development of thyroid dysfunction, inflammatory injury, epithelial-mesenchymal transition (EMT), and even fibrotic changes in the thyroid glands of SD rats. These findings increase our understanding of the toxic effects of arsenic exposure on the thyroid gland and its functions.

The activation of TLR4-MyD88 signaling promotes hepatic dysfunction and fibrotic changes in SD rats resulting from prolonged exposure to sodium arsenite

Arsenic, a poisonous metalloid element, is linked to liver diseases, but the exactmechanisms for this process are not yet to be completely elucidated. Toll like receptor 4 (TLR4), acting as a pathogenic pattern recognition receptor, plays a pivotal role in various inflammatory diseases via the myeloid differentiation factor 88 (MyD88) pathway. This study aims to investigate the involvement of the TLR4-MyD88 signaling pathway in liver injury induced by prolonged exposure to sodium arsenite (NaAsO2) in Sprague-Dawley rats. Our research findings demonstratethe activation of TLR4-MyD88 signaling pathway in long-term NaAsO2-exposed rat liver tissues, leading to a significant release of inflammatory factors, which suggests its potential involvement in the pathogenesis of NaAsO2-induced liver injury. We further administered lipopolysaccharide (LPS), a natural ligand of TLR4, and TAK-242, a specific inhibitor of TLR4, to rats in order to validate the specific involvement of the TLR4-MyD88 signaling pathway in NaAsO2-induced liver injury. The results showed that, 1 mg/kg.bw LPS treatment significantly activated TLR4-MyD88 signalling pathway and its mediated pro-inflammatory factors, leading to up-regulation of activation indicators in hepatic stellate cells (HSCs) as well as increased secretion levels of extracellular matrix (ECM) in the liver, and ultimately induced liver fibrosis and dysfunction in rats. Relevantly, subsequent administration of 0.5 mg/kg.bw TAK-242 significantly attenuated the expression levels of TLR4 and its associated proteins, mitigated collagen deposition, and partially improved liver fibrosis and dysfunction caused by NaAsO2 in rats. Our study fully confirms the pivotal role of the TLR4-MyD88 signaling in promoting liver injury induced by NaAsO2, thereby providing a novel molecular target for preventing and treating patients with arsenic poisoning-related liver injury.

Conditional deletion of CEACAM1 in hepatic stellate cells causes their activation

OBJECTIVES

Hepatic CEACAM1 expression declines with advanced hepatic fibrosis stage in patients with metabolic dysfunction-associated steatohepatitis (MASH). Global and hepatocyte-specific deletions of Ceacam1 impair insulin clearance to cause hepatic insulin resistance and steatosis. They also cause hepatic inflammation and fibrosis, a condition characterized by excessive collagen production from activated hepatic stellate cells (HSCs). Given the positive effect of PPARγ on CEACAM1 transcription and on HSCs quiescence, the current studies investigated whether CEACAM1 loss from HSCs causes their activation.

METHODS

We examined whether lentiviral shRNA-mediated CEACAM1 donwregulation (KD-LX2) activates cultured human LX2 stellate cells. We also generated LratCre + Cc1fl/fl mutants with conditional Ceacam1 deletion in HSCs and characterized their MASH phenotype. Media transfer experiments were employed to examine whether media from mutant human and murine HSCs activate their wild-type counterparts.

RESULTS

LratCre + Cc1fl/fl mutants displayed hepatic inflammation and fibrosis but without insulin resistance or hepatic steatosis. Their HSCs, like KD-LX2 cells, underwent myofibroblastic transformation and their media activated wild-type HSCs. This was inhibited by nicotinic acid treatment which blunted the release of IL-6 and fatty acids, both of which activate the epidermal growth factor receptor (EGFR) tyrosine kinase. Gefitinib inhibition of EGFR and its downstream NF-κB/IL-6/STAT3 inflammatory and MAPK-proliferation pathways also blunted HSCs activation in the absence of CEACAM1.

CONCLUSIONS

Loss of CEACAM1 in HSCs provoked their myofibroblastic transformation in the absence of insulin resistance and hepatic steatosis. This response is mediated by autocrine HSCs activation of the EGFR pathway that amplifies inflammation and proliferation.

Calcitriol Inhibits NaAsO2 Triggered Hepatic Stellate Cells Activation and Extracellular Matrix Oversecretion by Activating Nrf2 Signaling Pathway Through Vitamin D Receptor

Previous studies, including our own, have demonstrated that arsenic exposure can induce liver fibrosis, while the underlying mechanism remains unclear and there is currently no effective pharmacological intervention available. Recent research has demonstrated that vitamin D supplementation can ameliorate liver fibrosis caused by various etiologies, potentially through modulation of the Nrf2 signaling pathways. However, it remains unclear whether vitamin D intervention can mitigate arsenic-caused liver fibrosis. As is known hepatic stellate cells (HSCs) activation and extracellular matrix (ECM) deposition are pivotal in the pathogenesis of liver fibrosis. In this study, we investigated the intervention effect of calcitriol (a form of active vitamin D) on arsenite-triggered Lx-2 cells (a human hepatic stellate cell line) activation and ECM oversecretion. Additionally, we also elucidated the role and mechanism of Nrf2 antioxidant signaling pathway. Our results demonstrated that calcitriol intervention significantly inhibits Lx-2 cell activation and ECM oversecretion induced by arsenite exposure. Additionally, calcitriol activates Nrf2 and its downstream antioxidant enzyme expression in Lx-2 cells, thereby reducing ROS overproduction caused by arsenite exposure. Further investigation reveals that calcitriol activates the Nrf2 signaling pathway and inhibits arsenite-triggered Lx-2 cell activation and ECM oversecretion by targeting vitamin D receptor (VDR). In conclusion, this study has demonstrated that vitamin D intervention can effectively inhibit HSC activation and ECM oversecretion triggered by arsenite exposure through its antioxidant activity. This provides a novel strategy for targeted nutritional intervention in the treatment of arsenic-induced liver fibrosis.

Oral arsenite exposure induces inflammation and apoptosis in pulmonary tissue: acute and chronic evaluation in young and adult mice

Inorganic arsenic is a well-known environmental toxicant, and exposure to this metalloid is strongly linked with severe and extensive toxic effects in various organs including the lungs. In the present study, we aimed to investigate the acute and chronic effects of arsenite exposure on pulmonary tissue in young and adult mice. In brief, young and adult female Balb/C mice were exposed to 3 and 30 ppm arsenite daily via drinking water for 30 and 90 days. Subsequently, the animals were sacrificed and various histological and immunohistochemistry (IHC) analyses were performed using lung tissues. Our findings showed arsenite was found to cause dose-dependent pathological changes such as thickening of the alveolar septum, inflammatory cell infiltrations and lung fibrosis in young and adult mice. In addition, arsenite exposure significantly increased the expression of inflammatory markers NF-κB and TNF-α, indicating that arsenite-exposed mice suffered from severe lung inflammation. Moreover, the IHC analysis of fibrotic proteins demonstrated an increased expression of TGF-β1, α-SMA, vimentin and collagen-I in the arsenite-exposed mice compared to the control mice. This was accompanied by apoptosis, which was indicated by the upregulated expression of caspase-3 in arsenite-exposed mice compared to the control. Adult mice were generally found to be more prone to arsenite toxicity during chronic exposure relative to their younger counterparts. Overall, our findings suggest that arsenite in drinking water may induce dose-dependent and age-dependent structural and functional impairment in the lungs through elevating inflammation and fibrotic proteins.

Nod-like receptor protein 3 inflammasome-mediated pyroptosis contributes to chronic NaAsO2 exposure-induced fibrotic changes and dysfunction in the liver of SD rats

The metalloid arsenic, known for its toxic properties, is widespread presence in the environment. Our previous research has confirmed that prolonged exposure to arsenic can lead to liver fibrosis injury in rats, while the precise pathogenic mechanism still requires further investigation. In the past few years, the Nod-like receptor protein 3 (NLRP3) inflammasome has been found to play a pivotal role in the occurrence and development of liver injury. In this study, we administered varying doses of sodium arsenite (NaAsO2) and 10 mg/kg.bw MCC950 (a particular tiny molecular inhibitor targeting NLRP3) to Sprague-Dawley (SD) rats for 36 weeks to explore the involvement of NLRP3 inflammasome in NaAsO2-induced liver injury. The findings suggested that prolonged exposure to NaAsO2 resulted in pyroptosis in liver tissue of SD rats, accompanied by the fibrotic injury, extracellular matrix (ECM) deposition and liver dysfunction. Moreover, long-term NaAsO2 exposure activated NLRP3 inflammasome, leading to the release of pro-inflammatory cytokines in liver tissue. After treatment with MCC950, the induction of NLRP3-mediated pyroptosis and release of pro-inflammatory cytokines were significantly attenuated, leading to a decrease in the severity of liver fibrosis and an improvement in liver function. To summarize, those results clearly indicate that hepatic fibrosis and liver dysfunction induced by NaAsO2 occur through the activation of NLRP3 inflammasome-mediated pyroptosis, shedding new light on the potential mechanisms underlying arsenic-induced liver damage.

Conditional deletion of CEACAM1 causes hepatic stellate cell activation

Objectives

Hepatic CEACAM1 expression declines with advanced hepatic fibrosis stage in patients with MASH. Global and hepatocyte-specific deletions of Ceacam1 impair insulin clearance to cause hepatic insulin resistance and steatosis. They also cause hepatic inflammation and fibrosis, a condition characterized by excessive collagen production from activated hepatic stellate cells (HSCs). Given the positive effect of PPARγ on CEACAM1 transcriptoin and on HSCs quiescence, the current studies investigated whether CEACAM1 loss from HSCs causes their activation.

Methods

We examined whether lentiviral shRNA-mediated CEACAM1 donwregulation (KD-LX2) activates cultured human LX2 stellate cells. We also generated LratCre+Cc1 fl/fl mutants with conditional Ceacam1 deletion in HSCs and characterized their MASH phenotype. Media transfer experiments were employed to examine whether media from mutant human and murine HSCs activate their wild-type counterparts.

Results

LratCre+Cc1 fl/fl mutants displayed hepatic inflammation and fibrosis but without insulin resistance or hepatic steatosis. Their HSCs, like KD-LX2 cells, underwent myofibroblastic transformation and their media activated wild-type HDCs. This was inhibited by nicotinic acid treatment which stemmed the release of IL-6 and fatty acids, both of which activate the epidermal growth factor receptor (EGFR) tyrosine kinase. Gefitinib inhibition of EGFR and its downstream NF-κB/IL-6/STAT3 inflammatory and MAPK-proliferation pathways also blunted HSCs activation in the absence of CEACAM1.

Conclusions

Loss of CEACAM1 in HSCs provoked their myofibroblastic transformation in the absence of insulin resistance and hepatic steatosis. This response is mediated by autocrine HSCs activation of the EGFR pathway that amplifies inflammation and proliferation.

Artesunate Induces Ferroptosis in Hepatic Stellate Cells and Alleviates Liver Fibrosis via the ROCK1/ATF3 Axis

BACKGROUND AND AIMS

Development of fibrosis in chronic liver disease requires activation of hepatic stellate cells (HSCs) and leads to a poor outcome. Artesunate (Art) is an ester derivative of artemisinin that can induce ferroptosis in HSCs, and activated transcriptional factor 3 (ATF3) is an ATF/CREB transcription factor that is induced in response to stress. In this study, we examined the role of the Rho-associated protein kinase 1 (ROCK1)/ATF3 axis in Art-induced ferroptosis in HSCs.

METHODS

HSC activation and ferroptosis were studied in vitro by western blotting, polymerase chain reaction, immunofluorescence, and other assays. ATF3 electrophoretic mobility and ROCK1 protein stability were assayed by western blotting. Immunoprecipitation was used to detect the interaction of ROCK1 and ATF3, as well as ATF3 phosphorylation. A ubiquitination assay was used to verify ROCK1 degradation. Atf3-interfering and Rock1-overexpressing mice were constructed to validate the anti-hepatic fibrosis activity of Art in vivo.

RESULTS

Art induced ferroptosis in HSCs following glutathione-dependent antioxidant system inactivation resulting from nuclear accumulation of unphosphorylated ATF3 mediated by ROCK1-ubiquitination in vitro. Art also decreased carbon tetrachloride-induced liver fibrosis in mice, which was reversed by interfering with Atf3 or overexpressing Rock1.

CONCLUSIONS

The ROCK1/ATF3 axis was involved in liver fibrosis and regulation of ferroptosis, which provides an experimental basis for further study of Art for the treatment of liver fibrosis.

Alterations of Bax/Bcl-2 ratio contribute to NaAsO2 induced thyrotoxicity in human thyroid follicular epithelial cells and SD rats

The environmental toxicant arsenic causes various human diseases and threatens millions of people worldwide. Recently, a limited number of studies have revealed that exposure to arsenic is associated with thyroid dysfunction, indicating its toxicological impact on the thyroid gland, however, its precise forms of damage and underlying mechanisms remain largely unknown. Here, we sought to observe the thyrotoxicity of sodium arsenite (NaAsO2) on human thyroid follicular epithelial cells (Nthy-ori 3-1) and SD rats, and explore the role of Bax/Bcl-2 ratio in the above process. Our results displayed that NaAsO2 exerted a dose-dependent inhibitory effect on the viability of Nthy-ori 3-1 cells. Alongside the increase doses of NaAsO2 exposure, morphological changes and elevated LDH levels were observed. Furthermore, apoptosis rates increased in a dose- and time-dependent manner, accompanied by a decrease in Bcl-2 and an opposite change in Bax expression. SD rats were treated with 0, 2.5, 5, and 10 mg/kg NaAsO2 for 36 weeks. Our findings revealed that NaAsO2 exposure resulted in arsenic accumulation in thyroid tissue, elevated ratio of Bax/Bcl-2, and histopathological changes of thyroid in rats, which accompanied by the decreased serum T3 and T4 levels and the increased serum TSH level. Furthermore, T3 and T4 levels were negatively correlated with Bax expression, whereas positively correlated with Bcl-2 expression. Collectively, our results suggest that NaAsO2 exposure induces cytotoxicity in Nthy-ori 3-1 cells, causes structural damages and dysfunction of thyroid in SD rats, in which the imbalance of Bax/Bcl-2 ratio may play a significant role.

Role of SESTRIN2/AMPK/ULK1 pathway activation and lysosomes dysfunction in NaAsO2-induced liver injury under oxidative stress

Arsenic, a serious environmental poison to human health, is widely distributed in nature. As the main organ of arsenic metabolism, liver is easily damaged. In the present study, we found that arsenic exposure can cause liver injury in vivo and in vitro, to date the underlying mechanism of which is yet unclear. Autophagy is a process that depends on lysosomes to degrade damaged proteins and organelles. Here, we reported that oxidative stress can be induced and then activated the SESTRIN2/AMPK/ULK1 pathway, damaged lysosomes, and finally induced necrosis upon arsenic exposure in rats and primary hepatocytes, which was characterized by lipidation of LC3II, the accumulation of P62 and the activation of RIPK1 and RIPK3. Similarly, lysosomes function and autophagy can be damaged under arsenic exposure, which can be alleviated after NAC treatment and aggravated by Leupeptin treatment in primary hepatocytes. Moreover, we also found that the transcription and protein expressions of necrotic-related indicators RIPK1 and RIPK3 in primary hepatocytes were decreased after P62 siRNA. Taken together, the results revealed that arsenic can induce oxidative stress, activate SESTRIN2/AMPK/ULK1 pathway to damage lysosomes and autophagy, and eventually induce necrosis to damage liver.