Cadmium induces apoptosis of pig lymph nodes by regulating the PI3K/AKT/HIF-1α pathway

Low-dose cadmium induces lymphangiogenesis through activation of the STAT3 signaling pathway

Cadmium (Cd) is a widespread environmental toxicant that poses significant threat to public health. After intake, Cd is distributed throughout the body via blood and lymphatic circulation. However, the effect of Cd on lymphatic vessels has not been revealed. In this study, mice were exposed to 10 μM cadmium chloride through drinking water immediately after corneal alkali burn. In vivo analyses showed that Cd treatment enhances the alkali burn-induced corneal lymphangiogenesis, which is characterized by increased expression of lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1), prospero-related homeobox 1 (PROX-1) and vascular endothelial growth factor receptor 3 (VEGFR3). In vitro, the proliferation and migration of human dermal lymphatic endothelial cells (HDLECs) are increased by 1 μM Cd treatment, while inhibited by 10 μM Cd treatment. At a concentration of 1 μM, Cd specifically induces phosphorylation of signal transducer and activator of transcription 3 (STAT3), but has no effect on the MAPK, AKT, or NF-κB signaling pathway. In the presence of the STAT3 inhibitor STATTIC, Cd fails to induce HDLECs proliferation and migration. In addition, Cd upregulates VEGFR3 expression and its gene promoter activity in a STAT3-dependent manner. Our study suggests that low-dose Cd promotes lymphangiogenesis through activation of the STAT3 signaling pathway.

Cadmium exposure induces necroptosis of porcine spleen via ROS-mediated activation of STAT1/RIPK3 signaling pathway

Cadmium (Cd), a heavy metal, is used in a wide range of applications, such as plastics, electroplating process, electronics, and so forth. Due to its bioaccumulation ability, Cd can contaminate soil, water, air and food. To determine the effect of Cd exposure on the necroptosis in pig spleen and its mechanistic investigation, we constructed a model in pigs by feeding them food containing 20 mg/kg Cd. In this study, we analyzed the effects of Cd exposure on pig spleen through HE staining, Quantitative real-time PCR (qRT-PCR), Western blot (WB), and principal component analysis (PCA). Results show that Cd exposure can destroy the structure and function of pig spleen, which is closely related to necroptosis. Further results show that Cd exposure can induce necroptosis through ROS-mediated activation of Signal transducer and activator of transcription 1/Receptor-Interacting Serine/Threonine-Protein Kinase 3 (STAT1/RIPK3) signaling pathway in pig spleen. Additionally, Cd exposure also can affect the stability of mitochondrial-associated endoplasmic reticulum membrane (MAMs) structure, which also contributes to the process of necroptosis. Our study provides insights into the physiological toxicity caused by Cd exposure.

The role of hypoxia-inducible factor 1 alpha (HIF-1α) modulation in heavy metal toxicity

Hypoxia-inducible factor 1 (HIF-1) is an oxygen-sensing transcriptional regulator orchestrating a complex of adaptive cellular responses to hypoxia. Several studies have demonstrated that toxic metal exposure may also modulate HIF-1α signal transduction pathway, although the existing data are scarce. Therefore, the present review aims to summarize the existing data on the effects of toxic metals on HIF-1 signaling and the potential underlying mechanisms with a special focus on prooxidant effect of the metals. The particular effect of metals was shown to be dependent on cell type, varying from down- to up-regulation of HIF-1 pathway. Inhibition of HIF-1 signaling may contribute to impaired hypoxic tolerance and adaptation, thus promoting hypoxic damage in the cells. In contrast, its metal-induced activation may result in increased tolerance to hypoxia through increased angiogenesis, thus promoting tumor growth and contributing to carcinogenic effect of heavy metals. Up-regulation of HIF-1 signaling is mainly observed upon Cr, As, and Ni exposure, whereas Cd and Hg may both stimulate and inhibit HIF-1 pathway. The mechanisms underlying the influence of toxic metal exposure on HIF-1 signaling involve modulation of prolyl hydroxylases (PHD2) activity, as well as interference with other tightly related pathways including Nrf2, PI3K/Akt, NF-κB, and MAPK signaling. These effects are at least partially mediated by metal-induced ROS generation. Hypothetically, maintenance of adequate HIF-1 signaling upon toxic metal exposure through direct (PHD2 modulation) or indirect (antioxidant) mechanisms may provide an additional strategy for prevention of adverse effects of metal toxicity.

Ameliorative Effects of Oyster Protein Hydrolysates on Cadmium-Induced Hepatic Injury in Mice

Cadmium (Cd) is a widespread environmental toxicant that can cause severe hepatic injury. Oyster protein hydrolysates (OPs) have potential effects on preventing liver disease. In this study, thirty mice were randomly divided into five groups: the control, Cd, Cd + ethylenediaminetetraacetic acid (EDTA, 100 mg/kg), and low/high dose of OPs-treatment groups (100 mg/kg or 300 mg/kg). After continuous administration for 7 days, the ameliorative effect of OPs on Cd-induced acute hepatic injury in Cd-exposed mice was assessed. The results showed that OPs significantly improved the liver function profiles (serum ALT, AST, LDH, and ALP) in Cd-exposed mice. Histopathological analysis showed that OPs decreased apoptotic bodies, hemorrhage, lymphocyte accumulation, and inflammatory cell infiltration around central veins. OPs significantly retained the activities of SOD, CAT, and GSH-Px, and decreased the elevated hepatic MDA content in Cd-exposed mice. In addition, OPs exhibited a reductive effect on the inflammatory responses (IL-1β, IL-6, and TNF-α) and inhibitory effects on the expression of inflammation-related proteins (MIP-2 and COX-2) and the ERK/NF-κB signaling pathway. OPs suppressed the development of hepatocyte apoptosis (Bax, caspase-3, and Blc-2) and the activation of the PI3K/AKT signaling pathway in Cd-exposed mice. In conclusion, OPs ameliorated the Cd-induced hepatic injury by inhibiting oxidative damage and inflammatory responses, as well as the development of hepatocyte apoptosis via regulating the ERK/NF-κB and PI3K/AKT-related signaling pathways.

Mechanisms of Cd-induced Cytotoxicity in Normal Human Skin Keratinocytes: Implication for Human Health

Cadmium (Cd) is one of the toxic heavy metals found widely in the environment. Skin is an important target organ of Cd exposure. However, the adverse effects of Cd on human skin are still not well known. In this study, normal human skin keratinocytes (HaCaT cells) were studied for changes in cell viability, morphology, DNA damage, cycle, apoptosis, and the expression of endoplasmic reticulum (ER) stress-related genes (XBP-1, BiP, ATF-4, and CHOP) after exposure to Cd for 24 h. We found that Cd decreased cell viability in a concentration-dependent manner, with a median lethal concentration (LC₅₀) of 11 µM. DNA damage induction was evidenced by upregulation of the level of γ-H2AX. Furthermore, Cd induced G0/G1 phase cell cycle arrest and apoptosis in a dose-dependent manner and upregulated the mRNA levels of ER stress biomarker genes (XBP-1, BiP, ATF4, and CHOP). Taken together, our results showed that Cd induced cytotoxicity and DNA damage in HaCaT cells, eventually resulting in cell cycle arrest in the G0/G1 phase and apoptosis. In addition, ER stress may be involved in Cd-induced HaCaT apoptosis. Our data imply the importance of reducing Cd pollution in the environment to reduce its adverse impacts on human skin.

Cadmium induces apoptosis by miR-9-5p targeting PTEN and regulates the PI3K/AKT pathway in the piglet adrenal gland

Cadmium (Cd) is an environmental pollutant that can cause endocrine organ damage. To explore the effect of subacute CdCl₂ exposure on piglet adrenal gland tissue and its mechanism based on the establishment of this model, bioinformatics, TUNEL assay, western blot (WB), and qRT-PCR methods were used to detect related indicators. The results showed that after Cd exposure, antioxidant enzymes decreased, heat shock protein increased, and miR-9-5p-gene of phosphatase and tensin homolog (PTEN) upregulates the phosphatidylinositol-3-kinase (PI3K/AKT) pathway. After this pathway was activated, the expression of the apoptosis-related factors cysteinyl aspartate-specific proteinase 3 and 9 (caspase 3 and 9), B-cell lymphoma-2-associated X (BAX) was increased sharply, and the expression of B-cell lymphoma-2 (BCL2) was significantly decreased. The changes in these indicators indicate that Cd exposure induces apoptosis and causes tissue damage in the adrenal gland of piglets. This study aims to reveal the toxic effects of CdCl₂ in animals and will provide new ideas for the toxicology of Cd.

Arbutin Inhibited Heat Stress-Induced Apoptosis and Promoted Proliferation and Migration of Heat-Injured Dermal Fibroblasts and Keratinocytes by Activating PI3K/AKT Signaling Pathway

Objective. Studies have shown that arbutin has antioxidant and anti-inflammatory activities, which makes it suitable for treating skin wounds. We designed this study to investigate the effect of arbutin on heat-induced apoptosis, proliferation, and migration of dermal fibroblasts and keratinocytes and to explore the molecular mechanism. Methods. In vitro, HaCAT and dermal fibroblast (DFL) cells were cultured and used to establish a heat stress-injured skin cell model. We investigated the effects of arbutin on apoptosis, proliferation, and migration of HaCAT and DFL cells after heat stress injury. We then used immunoblotting to detect the expression of p-PI3K, PI3K, p-AKT, and AKT proteins for studying the underlying mechanisms and used a PI3K/AKT inhibitor (LY294002) to verify the efficacy of arbutin in HaCAT and DFL cells with heat stress injury. Results. Arbutin strongly inhibited heat stress-induced apoptosis, proliferation inhibition, and migration inhibition of HaCAT and DFL cells in vitro. Our results also showed that arbutin strongly decreased the ratio of Bax/Bcl2 protein expression and PCNA protein expression in HaCAT and DFL cells after treatment with heat stress. Furthermore, we also found that arbutin significantly increased the ratio of p-PI3K/PI3K and p-AKT/AKT protein expression, and LY294002 markedly reversed the effect of arbutin on heat stress-induced apoptosis, proliferation inhibition, and migration inhibition of HaCAT and DFL cells. Conclusion. Our finding indicated that arbutin inhibited heat stress-induced apoptosis and promoted proliferation and migration of heat-injured dermal fibroblasts and epidermal cells by activating the PI3K/AKT signaling pathway, suggesting that arbutin may provide an alternative therapeutic approach for the treatment of skin injury.

Cadmium exposure causes mitochondrial fission and fusion disorder in the pig hypothalamus via the PI3K/AKT pathway

Cadmium (Cd) is the main environmental pollutant causing endocrine and nervous system dysfunction in animals. High doses of Cd cause cytotoxicity, including programmed necrosis and apoptosis, which has aroused widespread concern. Mitochondrial dynamics plays a key role in programmed necrosis and apoptosis of endocrine organs. Nevertheless, there is a lack of information on the relationship between Cd-induced programmed necrosis/apoptosis of the hypothalamus and the mitochondrial fusion-fission balance. Therefore, a hypothalamic injury model of Cd exposure was established by adding 20 mg/kg CdCl₂ to the basic pig diet for 40 days. Analysis of the Cd toxicity mechanism was conducted by inductively coupled plasma mass spectrometry, hematoxylin and eosin staining, the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, and quantitative reverse transcription-polymerase chain reaction, as well as western blot analyses. The results suggested that exposure to Cd inhibited the expression of PI3K and AKT, interfered with the balance of mitochondrial fusion and division, downregulated the expression of Mfn2, Mfn1, and OPA1, and upregulated the expression of Drp1 and Mff, which led to cell apoptosis and programmed necrosis in the pig hypothalamus. This study finds that cadmium exposure leads to mitochondrial fission and fusion dysfunction in porcine hypothalamus via the PI3K/AKT pathway.

Heavy metal and metalloid - induced reproductive toxicity

Heavy metals and metalloid exposure are among the most common factors responsible for reproductive toxicity in human beings. Several studies have indicated that numerous metals and metalloids can display severe adverse properties on the human reproductive system. Metals like lead, silver, cadmium, uranium, vanadium, and mercury and metalloids like arsenic have been known to induce reproductive toxicity. Moderate to minute quantities of lead may affect several reproductive parameters and even affect semen quality. The ecological and industrial exposures to the various heavy metals and metalloids have disastrous effects on the reproductive system ensuing in infertility. This work emphasizes the mechanism and pathophysiology of the aforementioned heavy metals and metalloids in reproductive toxicity. Additionally, this work aims to cover the classical protective mechanisms of zinc, melatonin, chelation therapy, and other trending methods to prevent heavy metal-induced reproductive toxicity.

Selenium protects against cadmium-induced cardiac injury by attenuating programmed cell death via PI3K/AKT/PTEN signaling

Cadmium (Cd) is an environmental pollutant that has an enormous influence on agricultural production, but selenium (Se) can alleviate its toxicity. The present study aimed to illustrate the effects of Se on Cd-induced heart injury. All 40 rabbits were randomly divided into four groups: control group, Se [0.5 mg kg^-1 ·body weight (BW)] group, Cd (1 mg kg^-1 ·BW) group, and Se + Cd group. After 30 days of feeding, morphological changes, the levels of oxidative stress and myocardial enzyme, the content of cardiac troponin T, programmed cell death (pyroptosis, autophagy and apoptosis), and PI3K/AKT/PTEN transduction capacity were observed. The results showed that Cd destroyed the physiological balance of trace elements and caused myocardial damage, increased the cardiac oxidative damage and led to programmed cell death. Coadministration of Se prominently ameliorated histological lesions and improved cardiac function of hearts in Cd-induced rabbits. Furthermore, Se exerted detoxification and oxidation resistance, maintained trace element homeostasis, and alleviated the changes of mRNA and protein levels of pyroptosis-, autophagy- and apoptosis-controlling factors and PI3K/AKT/PTEN signal molecules caused by Cd. In conclusion, Se might protect against Cd-induced pyroptosis, autophagy and apoptosis by interfering with PI3K/AKT/PTEN signaling in heart.

AMPK/PPAR-γ/NF-κB axis participates in ROS-mediated apoptosis and autophagy caused by cadmium in pig liver

The experiment was conducted to investigate the effects of Cadmium (Cd) on growth performance, blood biochemical parameters, oxidative stress, hepatocyte apoptosis and autophagy of weaned piglets. A total of 12 healthy weaned piglets were randomly assigned to the control and the Cd group, which were fed with a basal diet and the basal diet supplemented with 15 ± 0.242 mg/kg CdCl₂ for 30 d, respectively. Our results demonstrated that Cd significantly decreased final body weight, average daily feed intake (ADFI), average daily gain (ADG) and increased feed-to-gain (F/G) ratio (P < 0.05). For blood biochemical parameters, Cd treatment significantly decreased the red blood cell (RBC), hemoglobin (HGB), hematocrit (HCT), total protein, albumin, copper content and iron content (P < 0.05). In addition, liver injury was observed in the Cd-exposed group. Our results also demonstrated that Cd exposure contributed to the production of ROS, activated the AMPK/PPAR-γ/NF-κB pathway (increasing the expressions of P-AMPK/AMPK, NF-κB, I-κB-β, COX-2, and iNOS, decreasing the expressions of PPAR-γ and I-κB-α), finally induced autophagy (increasing the expressions of Beclin-1, the ratio of LC3-II/LC3-I and p62), and apoptosis (increasing the expressions of Bax, Bak, Caspase-9, and Caspase-3, decreasing the expression of Bcl-2). Overall, these findings revealed the vital role of AMPK/PPAR-γ/NF-κB pathway in Cd-induced liver apoptosis and autophagy, which provided deeper insights into a better understanding of Cd-induced hepatotoxicity.

Cadmium exposure activates the PI3K/AKT signaling pathway through miRNA-21, induces an increase in M1 polarization of macrophages, and leads to fibrosis of pig liver tissue

Cadmium (Cd) is a toxic substance that pollutes the environment with multiple organs. Long-term exposure to Cd can cause fibrosis in the lungs and other organs of animal body. This article explored the effects of subacute Cd exposure on pig liver fibrosis, as well as the polarization of microRNA (miRNA) and M1/M2 macrophages during this process. Based on the establishment of the pig subacute CdCl2 exposure model, we used immunofluorescence staining, Masson staining, qRT-PCR and western blotting to conduct further research. The results showed that Cd exposure can increase the expression of miRNA-21, decrease the expression of TGF-β and SMAD7, increase the expression of PI3K/AKT signaling pathway, cause the M1/M2 imbalance and the increase of M1 polarization. Meantime, it causes the secretion of inflammatory cytokines (TNF-α, IL-1β, and IL-6), and causes an imbalance in the expression of TIMP1, MMP2, and MMP9, which are related to the degree of fibrosis. And the expression of α-SMA, COL1 and COL3 were up-regulated. In the pig, these results indicate that liver fibrosis caused by subacute CdCl2 exposure is induced by the M1 polarization of macrophages through the PI3K/AKT signaling pathway activated by miRNA-21 signaling pathway. These research results not only enrich the theoretical basis and reference value of Cd toxicology research, but also provide new references and new research ideas for comparative medicine.

H2S exposure induces cell death in the broiler thymus via the ROS-initiated JNK/MST1/FOXO1 pathway

Hydrogen sulfide (H₂S) is a common toxic gas in chicken houses that endangers the health of poultry. Harbin has a cold climate in winter, and the conflict between heat preservation and ventilation in poultry houses is obvious. In this study, we investigated the H₂S content in chicken houses during winter in Harbin and found that the H₂S concentration exceeded the national standard in individual chicken houses. Then, a model of H₂S exposure was established in an environmental simulation chamber. We also developed a NaHS exposure model of chicken peripheral blood lymphocytes in vitro. Proteomics analysis was used to reveal the toxicology of thymus injury in broilers, the FOXO signaling pathway was determined to be significantly enriched, ROS bursts and JNK/MST1/FOXO1 pathway activation induced by H₂S exposure were detected, and ROS played an important switch role in the JNK/MST1/FOXO1 pathway. In addition, H₂S exposure-induced thymus cell death involved immune dysregulation. Overall, the present study adds data for H₂S contents in chicken houses, provides new findings for the mechanism of H₂S poisoning and reveals a new regulatory pathway in immune injury.

Cadmium induces the thymus apoptosis of pigs through ROS-dependent PTEN/PI3K/AKT signaling pathway

Cadmium (Cd) is a transition metal that is toxic to living organisms in the environment and endangers living organisms. To explore whether Cd induces apoptosis in pig thymus and its possible mechanism, the role Cd induction of the PTEN/PI3K/Akt pathway in apoptosis of thymus cells was studied in pigs. We found that Cd exposure (the feed is treated with Cd) significantly increased Cd accumulation in the thymus of pigs. The TUNEL assay confirmed the typical apoptotic characteristics of thymus in Cd group. Moreover, in the Cd group, the activities of antioxidant indices decreased significantly, while the levels of oxidative stress indexes increased significantly, and the mRNA levels of GSH, CAT, Gpx1, GST, SOD1, and SOD2 decreased obviously. Moreover, the mRNA and protein levels of PTEN/PI3K/AKT and apoptosis-related genes were detected by qPCR and western blotting. The results show that the expressions of PI3K and AKT decreased, while the expression of PTEN increased, indicating that pathway activated. With the PTEN/PI3K/AKT pathway regulating, Bcl-2 expression decreased. Conversely, the mRNA and protein expression of apoptosis-related genes were up-regulated. In conclusion, accumulation of Cd in the pigs caused oxidative damage to immune tissues. In addition, Cd-induced oxidative stress activates the PTEN/PI3K/AKT pathway, inducing apoptosis in the thymus of pigs.

Cadmium exposure induces inflammation and necroptosis in porcine adrenal gland via activating NF-κB/MAPK pathway

Cadmium (Cd) is a heavy metal harmful to animals and humans. Cd exposure causes inflammation or necroptosis in many tissues, including adrenal tissue. However, the current researches on the effects of Cd²⁺ in adrenal tissues are not enough. Therefore, in our experiment Cd chloride (CdCl₂) was added to the piglet's diet at a concentration of 20 mg/kg to study the effects of Cd²⁺ exposure on the porcine adrenal tissue. Our results showed that Cd²⁺ exposure could cause inflammation by activating the nuclear factor kappa-B (NF-κB) pathway, which in turn induced necroptosis in adrenal tissue with the activated mitogen-activated protein kinase (MAPK) pathway. The expression increase of inflammatory factors and necroptosis downstream genes, and the downregualtion of cysteinyl aspartate specific proteinase 8 (Caspase 8) proved that Cd²⁺ exposure caused inflammation and necroptosis in adrenal tissue. We conclude that this report provides more basic theoretical data for exploring the mechanism of adrenal injury.

Cadmium-induced Oxidative Stress and Immunosuppression Mediated Mitochondrial Apoptosis via JNK-FoxO3a-PUMA pathway in Common Carp (Cyprinus carpio L.) Gills

Cadmium (Cd)-caused water environment pollution has become a matter of concern. Gill is an organ with respiratory and mucosal immune functions, and is also one of the organs directly attacked by pollutants. It was found that excess Cd could cause Cd accumulation and gill injury in carp. However, the mechanism of Cd-caused damage in common carp gills is still unclear. Oxidative stress, immunosuppression, and apoptosis took part in the mechanism of poisoning caused by some harmful substances. The aim of the study was to investigate complex molecular mechanism of apoptotic injury caused by Cd in common carp gills. Hence, in this study, we established a Cd poisoning model to explore whether excess Cd can induce apoptosis through observing histomorphology and apoptotic cells; and determining mineral elements, oxidative stress-related factors, immune-related, and apoptosis-related genes in common carp gills. Fifty-four fish were randomly separated into the control group and the Cd group and were cultured for 45 days. The water of the control group was drinking water and the water of the Cd group was CdCl₂-added drinking water (0.26 mg/L Cd). In our results, we found that excess Cd increased Cd level, decreased the levels of essential mineral elements (Cu, Fe, Zn, and Mn), damaged mitochondria, and increased apoptotic cells in common carp gills, meaning that excess Cd caused Cd accumulation and apoptotic injury via mitochondrion in common carp gills. Furthermore, we found that Cd inhibited anti-apoptosis-related gene Bcl-2 and stimulated pro-apoptosis-related genes (JNK, FoxO3a, PUMA, Bax, Apaf-1, Caspase-9, and Caspase-3) on 15th, 30th, and 45th days. Above data meant that Cd exposure caused apoptosis via mitochondrion and JNK-FoxO3a-PUMA pathway in common carp gills. In addition, in our experiment, Cd treatment increased oxidants (H₂O₂ and MDA) and decreased antioxidants (CAT, GPx, GST, SOD, T-AOC, and GSH), indicating that Cd caused oxidative stress via oxidation/antioxidation imbalance. Meanwhile, compared to the control group, T-help 17 (Th17) cell-related factors (IL-17, TNF-α, and RORγ) were up-regulated, regulatory T (Treg) cell-related factors (IL-10 and Foxp3) were down-regulated, and IL-17/IL-10, TNF-α/IL-10, and RORγ/Foxp3 were increased in Cd-exposed group; meaning that excess Cd induced immunosuppression via the imbalance of Th17/Treg cells. Taken together, our findings indicated that JNK-FoxO3a-PUMA pathway and mitochondrion participated in oxidative stress and immunosuppression-mediated apoptosis caused by Cd in common carp (Cyprinus carpio L.) gills. Our data provided new perspectives on the negative effects of heavy metal pollutants on fish.