Calcimimetic compound NPS R-467 protects against chronic cadmium-induced mouse kidney injury by restoring autophagy process

Cadmium promoted LPS-induced inflammation through TLR4/IκBα/NFκ-B signaling by increasing ROS-mediated incomplete autophagy

Cadmium (Cd) exposure is considered as non-infectious stressor to human and animal health. Recent studies suggest that the immunotoxicity of low dose Cd is not directly apparent, but disrupts the immune responses when infected with some bacteria or virus. But how Cd alters the adaptive immunity organ and cells remains unclear. In this study, we applied lipopolysaccharide (LPS, infectious stressor) to induced inflammation in spleen tissues and T cells, and investigated the effects after Cd exposure and the underlying mechanism. Cd exposure promoted LPS-induced the expressions of the inflammatory factors, induced abnormal initiation of autophagy, but blocked autophagic flux. The effects Cd exposure under LPS activation were reversed by the autophagy promoter Rapamycin. Under LPS activation conditions, Cd also induced oxidative stress by increasing the levels of reactive oxygen species (ROS) and malondialdehyde (MDA), and reducing total antioxidant capacity (T-AOC) activity. The increased superoxide dismutase (SOD) activity after Cd exposure might be a negative feedback or passive adaptive regulation of oxidative stress. Cd-increased autophagic flux inhibition and TNF-α expression were reversed by ROS scavenger α-tocopherol (TCP). Furthermore, under LPS activation condition, Cd promoted activation of toll-like receptor 4 (TLR4)/IκBα/NFκ-B signaling pathway and increased TLR4 protein stability, which were abolished by the pretreatment of Rapamycin. The present study confirmed that, by increasing ROS-mediated inhibiting autophagic degradation of TLR4, Cd promoted LPS-induced inflammation in spleen T cells. This study identified the mechanism of autophagy in Cd-aggravated immunotoxicity under infectious stress, which could arouse public attention to synergistic toxicity of Cd and bacterial or virus infection.

NPS-2143 inhibit glioma progression by suppressing autophagy through mediating AKT-mTOR pathway

Gliomas are the most common tumours in the central nervous system. In the present study, we aimed to find a promising anti-glioma compound and investigate the underlying molecular mechanism. Glioma cells were subjected to the 50 candidate compounds at a final concentration of 10 μM for 72 h, and CCK-8 was used to evaluate their cytotoxicity. NPS-2143, an antagonist of calcium-sensing receptor (CASR), was selected for further study due to its potent cytotoxicity to glioma cells. Our results showed that NPS-2143 could inhibit the proliferation of glioma cells and induce G1 phase cell cycle arrest. Meanwhile, NPS-2143 could induce glioma cell apoptosis by increasing the caspase-3/6/9 activity. NPS-2143 impaired the immigration and invasion ability of glioma cells by regulating the epithelial-mesenchymal transition process. Mechanically, NPS-2143 could inhibit autophagy by mediating the AKT-mTOR pathway. Bioinformatic analysis showed that the prognosis of glioma patients with low expression of CASR mRNA was better than those with high expression of CASR mRNA. Gene set enrichment analysis showed that CASR was associated with cell adhesion molecules and lysosomes in glioma. The nude mice xenograft model showed NPS-2143 could suppress glioma growth in vivo. In conclusion, NPS-2143 can suppress the glioma progression by inhibiting autophagy.

Interactive mechanism between connexin43 and Cd-induced autophagic flux blockage and gap junctional intercellular communication dysfunction in rat hepatocytes

Cadmium (Cd) is a significant environmental contaminant known for its potential hepatotoxic effects. However, the precise mechanisms underlying Cd-induced hepatotoxicity have yet to be fully understood. Therefore, the purpose of this study was to investigate the dynamic role of connexin 43 (Cx43) in response to Cd exposure, particularly its impact on gap junctional intercellular communication (GJIC) and autophagy in hepatocytes. To establish an in vitro model of Cd-induced hepatocyte injury, the Buffalo rat liver 3A cell line (BRL3A) was utilized.In order to elucidate the mechanism by which Cx43 influences Cd-induced hepatocyte toxic injury, inhibitors of Cx43 (Dynasore) and P-Cx43 (Ro318220) were employed in the model. The findings revealed that inhibiting Cx43 and its phosphorylation further compromised GJIC function, exacerbating the impairment, while also intensifying the blockage of autophagic flux. To gain further insight into the role of Cx43, siRNA was utilized to knock down Cx43 expression, yielding similar results. The down-regulation of Cx43 expression was found to worsen the morphological damage induced by cadmium exposure, diminish the cell proliferation capacity of BRL3A cells, and exacerbate the disruption of GJIC and autophagic flow caused by Cd.These findings suggest that Cx43 may serve as a potential therapeutic target for the treatment of liver damage resulting from Cd exposure. By targeting Cx43, it may be possible to mitigate the adverse effects of Cd on hepatocytes.

Recent insights into autophagy and metals/nanoparticles exposure

Some anthropogenic pollutants, such as heavy metals and nanoparticles (NPs), are widely distributed and a major threat to environmental safety and public health. In particular, lead (Pb), cadmium (Cd), chromium (Cr), arsenic (As), and mercury (Hg) have systemic toxicity even at extremely low concentrations, so they are listed as priority metals in relation to their significant public health burden. Aluminum (Al) is also toxic to multiple organs and is linked to Alzheimer's disease. As the utilization of many metal nanoparticles (MNPs) gradually gain traction in industrial and medical applications, they are increasingly being investigated to address potential toxicity by impairing certain biological barriers. The dominant toxic mechanism of these metals and MNPs is the induction of oxidative stress, which subsequently triggers lipid peroxidation, protein modification, and DNA damage. Notably, a growing body of research has revealed the linkage between dysregulated autophagy and some diseases, including neurodegenerative diseases and cancers. Among them, some metals or metal mixtures can act as environmental stimuli and disturb basal autophagic activity, which has an underlying adverse health effect. Some studies also revealed that specific autophagy inhibitors or activators could modify the abnormal autophagic flux attributed to continuous exposure to metals. In this review, we have gathered recent data about the contribution of the autophagy/mitophagy mediated toxic effects and focused on the involvement of some key regulatory factors of autophagic signaling during exposure to selected metals, metal mixtures, as well as MNPs in the real world. Besides this, we summarized the potential significance of interactions between autophagy and excessive reactive oxygen species (ROS)-mediated oxidative damage in the regulation of cell survival response to metals/NPs. A critical view is given on the application of autophagy activators/inhibitors to modulate the systematic toxicity of various metals/MNPs.

Cadmium Disrupted ER Ca2+ Homeostasis by Inhibiting SERCA2 Expression and Activity to Induce Apoptosis in Renal Proximal Tubular Cells

Cadmium (Cd²⁺) exposure induces chronic kidney disease and renal cancers, which originate from injury and cancerization of renal tubular cells. Previous studies have shown that Cd²⁺ induced cytotoxicity by disrupting the intracellular Ca²⁺ homeostasis that is physically regulated by the endoplasmic reticulum (ER) Ca²⁺ store. However, the molecular mechanism of ER Ca²⁺ homeostasis in Cd²⁺-induced nephrotoxicity remains unclear. In this study, our results firstly revealed that the activation of calcium-sensing receptor (CaSR) by NPS R-467 could protect against Cd²⁺ exposure-induced cytotoxicity of mouse renal tubular cells (mRTEC) by restoring ER Ca²⁺ homeostasis through the ER Ca²⁺ reuptake channel sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA). Cd²⁺-induced ER stress and cell apoptosis were effectively abrogated by SERCA agonist CDN1163 and SERCA2 overexpression. In addition, in vivo, and in vitro results proved that Cd²⁺ reduced the expressions of SERCA2 and its activity regulator phosphorylation phospholamban (p-PLB) in renal tubular cells. Cd²⁺-induced SERCA2 degradation was suppressed by the treatment of proteasome inhibitor MG132, which suggested that Cd²⁺ reduced SERCA2 protein stability by promoting the proteasomal protein degradation pathway. These results suggested that SERCA2 played pivotal roles in Cd²⁺-induced ER Ca²⁺ imbalance and stress to contribute to apoptosis of renal tubular cells, and the proteasomal pathway was involved in regulating SERCA2 stability. Our results proposed a new therapeutic approach targeting SERCA2 and associated proteasome that might protect against Cd²⁺-induced cytotoxicity and renal injury.

Taurine Alleviates Cadmium-Induced Hepatotoxicity by Regulating Autophagy Flux

Our previous studies have confirmed that cadmium (Cd) exposure causes hepatotoxicity; it also induces autophagy and blocks the autophagy flux. Therefore, we hypothesized that Cd hepatotoxicity could be alleviated through nutritional intervention. Taurine (Tau) has various biological functions such as acting as an antioxidant, acting as an anti-inflammatory, and stabilizing cell membranes. In order to explore the protective effect and internal mechanism of Tau on Cd-induced hepatotoxicity, normal rat liver cell line BRL3A cells were treated with Cd alone or in combination with Tau to detect cell injury and autophagy-related indexes in this study. We found that Tau can alleviate Cd-induced cell-proliferation decline and morphological changes in the cell. In addition, Tau activates autophagy and alleviates the blockage of Cd-induced autophagy flux. In this process, lysosome acidification and degradation were enhanced, and autophagosomes were further fused with lysosomes. Then, we found that Tau alleviated autophagic flux block by promoting the transfer of membrane fusion proteins STX17 and SNAP29 to autophagosomes and the translocation of VAMP8 to lysosomes, which in turn attenuated the hepatocyte injury induced by Cd exposure. This will further reveal the hepatotoxicity mechanism of Cd and provide the theoretical basis for the prevention and treatment of Cd poisoning.

Molybdenum and cadmium co-exposure induces CaMKKβ/AMPK/mTOR pathway mediated-autophagy by subcellular calcium redistribution in duck renal tubular epithelial cells

Excessive molybdenum (Mo) and cadmium (Cd) are toxic environmental pollutants. Our previous research confirmed excessive Mo and Cd co-induced calcium homeostasis disorder and autophagy in duck kidneys, but how calcium ion (Ca²⁺) regulates autophagy is unclear. The results revealed that the Mo- and/or Cd-induced cytosolic Ca²⁺ concentration ([Ca²⁺]_c) increase mainly came from intracellular calcium stores. Mo and/or Cd caused mitochondrial Ca²⁺ content ([Ca²⁺]_mit) and [Ca²⁺]_c increase with endoplasmic reticulum (ER) Ca²⁺ content ([Ca²⁺]_ER) decrease and upregulated calcium homeostasis-related factor expression levels, but 2-Aminoethoxydiphenyl borate (2-APB) reversed subcellular Ca²⁺ redistribution. Increased Phospholipase C (PLC) and inositol 1,4,5-trisphosphate (IP₃) activities and inositol 1,4,5-trisphosphate receptor (IP₃R) expression level were observed in Mo- and/or Cd-treated cells, which was reversed by the PLC inhibitor U-73122. 2-APB and 1,2-Bis (2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester (BAPTA-AM) addition mitigated [Ca²⁺]_c and autophagy (variations in microtubule-associated protein light chain 3 (LC3), LC3B-II/LC3B-I, autophagy related 5 (ATG5), sequestosome-1(P62), programmed cell death-1 (Beclin-1) and Dynein expression levels, LC3 puncta, autophagosomes and acid vesicle organelles) under Mo and/or Cd treatment, respectively, while thapsigargin (TG) had the opposite impacts. Additionally, the calmodulin-dependent protein kinase kinase β (CaMKKβ) inhibitor STO-609 reversed the increased CaMKKβ, adenosine 5'-monophosphate-activated protein kinase (AMPK), Beclin-1, and LC3B-II/LC3B-I protein expression levels and reduced mammalian target of rapamycin (mTOR) and P62 protein expression levels in Mo- and/or Cd-exposed cells. Collectively, the results confirmed that [Ca²⁺]_c overload resulted from PLC/IP₃/IP₃R pathway-mediated ER Ca²⁺ release, and then activated autophagy by the CaMKKβ/AMPK/mTOR pathway in Mo- and/or Cd-treated duck renal tubular epithelial cells.

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.

Calcium-Sensing Receptor (CaSR)-Mediated Intracellular Communication in Cardiovascular Diseases

The calcium-sensing receptor (CaSR), a G-protein-coupled receptor (GPCR), is a cell-surface-located receptor that can induce highly diffusible messengers (IP3, Ca²⁺, cAMP) in the cytoplasm to activate various cellular responses. Recently, it has also been suggested that the CaSR mediates the intracellular communications between the endoplasmic reticulum (ER), mitochondria, nucleus, protease/proteasome, and autophagy-lysosome, which are involved in related cardiovascular diseases. The complex intracellular signaling of this receptor challenges it as a valuable therapeutic target. It is, therefore, necessary to understand the mechanisms behind the signaling characteristics of this receptor in intracellular communication. This review provides an overview of the recent research progress on the various regulatory mechanisms of the CaSR in related cardiovascular diseases and the heart-kidney interaction; the associated common causes are also discussed.

Curative Potential of Substances with Bioactive Properties to Alleviate Cd Toxicity: A Review

Rapid urbanization and industrialization have led to alarming cadmium (Cd) pollution. Cd is a toxic heavy metal without any known physiological function in the organism, leading to severe health threat to the population. Cd has a long half-life (10-30 years) and thus it represents serious concern as it to a great extent accumulates in organs or organelles where it often causes irreversible damage. Moreover, Cd contamination might further lead to certain carcinogenic and non-carcinogenic health risks. Therefore, its negative effect on population health has to be minimalized. As Cd is able to enter the body through the air, water, soil, and food chain one possible way to defend and eliminate Cd toxicities is via dietary supplements that aim to eliminate the adverse effects of Cd to the organism. Naturally occurring bioactive compounds in food or medicinal plants with beneficial, mostly antioxidant, anti-inflammatory, anti-aging, or anti-tumorigenesis impact on the organism, have been described to mitigate the negative effect of various contaminants and pollutants, including Cd. This study summarizes the curative effect of recently studied bioactive substances and mineral elements capable to alleviate the negative impact of Cd on various model systems, supposing that not only the Cd-derived health threat can be reduced, but also prevention and control of Cd toxicity and elimination of Cd contamination can be achieved in the future.

Protective effect of quercetin on cadmium-induced renal apoptosis through cyt-c/caspase-9/caspase-3 signaling pathway

Cadmium (Cd), a heavy metal, has harmful effects on animal and human health, and it can also obviously induce cell apoptosis. Quercetin (Que) is a flavonoid compound with antioxidant and other biological activities. To investigate the protective effect of Que on Cd-induced renal apoptosis in rats. 24 male SD rats were randomly divided into four groups. They were treated as follows: control group was administered orally with normal saline (10 ml/kg); Cd group was injected with 2 mg/kg CdCl₂ intraperitoneally; Cd + Que group was injected with 2 mg/kg CdCl₂ and intragastric administration of Que (100 mg/kg); Que group was administered orally with Que (100 mg/kg). The experimental results showed that the body weight of Cd-exposed rats significantly decreased and the kidney coefficient increased. In addition, Cd significantly increased the contents of Blood Urea Nitrogen, Creatinine and Uric acid. Cd also increased the glutathione and malondialdehyde contents in renal tissues. The pathological section showed that Cd can cause pathological damages such as narrow lumen and renal interstitial congestion. Cd-induced apoptosis of kidney, which could activate the mRNA and protein expression levels of Cyt-c, Caspase-9 and Caspase-3 were significantly increased. Conversely, Que significantly reduces kidney damage caused by Cd. Kidney pathological damage was alleviated by Que. Que inhibited Cd-induced apoptosis and decreased Cyt-c, Caspase-9 and Caspase-3 proteins and mRNA expression levels. To sum up, Cd can induce kidney injury and apoptosis of renal cells, while Que can reduce Cd-induced kidney damage by reducing oxidative stress and inhibiting apoptosis. These results provide a theoretical basis for the clinical application of Que in the prevention and treatment of cadmium poisoning.

Dual role of cadmium in rat liver: Inducing liver injury and inhibiting the progression of early liver cancer

The heavy metal cadmium (Cd) can induce damage in liver and liver cancer cells; however, the mechanism underlying its toxicity needs to be further verified in vivo. We daily administered CdCl2 to adult male rats at different dosages via gavage for 12 weeks and established rat liver injury model and liver cancer model to study the dual role of Cd in rat liver. Increased exposure to Cd resulted in abnormal liver function indicators, pathological degeneration, rat liver cell necrosis, and proliferation of collagen fibres. Using immunohistochemistry, we found that the area of GST-P-positive precancerous liver lesions decreased in a dose-dependent manner. Real-time quantitative polymerase chain reaction, western blot, immunohistochemistry, and transmission electron microscopy revealed that Cd induced mitophagy, as well as mitophagy blockade, as evidenced by the downregulation of TOMM20 and upregulation of LC3II and P62 with increasing Cd dose. Next, the expression of PINK1/Parkin, a classic signalling pathway protein that regulates mitophagy, was examined. Cd was found to promote PINK1/Parkin expression, which was proportional to the Cd dose. In conclusion, Cd activates PINK1/Parkin-mediated mitophagy in a dose-dependent manner. Mitophagy blockade likely aggravates Cd toxicity, leading to the dual role of inducing liver injury and inhibiting the progression of early liver cancer.

In vivo assessment of molybdenum and cadmium co-induce nephrotoxicity via causing calcium homeostasis disorder and autophagy in ducks (Anas platyrhyncha)

Excess molybdenum (Mo) and cadmium (Cd) are widespread environmental and industrial metal pollutants. To evaluate the combined effects of Mo and Cd on calcium homeostasis and autophagy in duck kidneys. 160 healthy 7-day-old ducks (Anas platyrhyncha) were randomized into 4 groups and given to a basic diet, adding various doses of Mo or/and Cd for 16 weeks. On the 4th, 8th, 12th and 16th weeks, kidney tissues were collected. The study exhibited that Mo or/and Cd caused histological abnormality, reduced the activities of Ca2+ ATPase, Mg2+ ATPase, Na+-K+ ATPase and Ca2+-Mg2+ ATPase, K and Mg contents, and increased Na and Ca contents, upregulated CaMKKβ, CaMKIIɑ, CaN, IP3R, GRP78, GRP94, CRT mRNA levels and CaMKIIɑ, CaN, IP3R protein levels. Moreover, exposure to Mo or/and Cd notably promoted the amount of autophagosomes and LC3II immunofluorescence, upregulated AMPKα1, ATG5, Beclin-1, LC3A, LC3B mRNA levels and Beclin-1, LC3II/LC3I protein levels, downregulated mTOR, Dynein, P62 mRNA levels and P62 protein level. The changes of above indicators in combined group were more obvious. Overall, the results suggest that Mo and Cd co-exposure may can synergistically induce nephrotoxicity via causing calcium homeostasis disorder and autophagy in ducks.

Calcium Signaling Mediates Cell Death and Crosstalk with Autophagy in Kidney Disease

The kidney is an important organ for the maintenance of Ca²⁺ homeostasis in the body. However, disruption of Ca²⁺ homeostasis will cause a series of kidney diseases, such as acute kidney injury (AKI), chronic kidney disease (CKD), renal ischemia/reperfusion (I/R) injury, autosomal dominant polycystic kidney disease (ADPKD), podocytopathy, and diabetic nephropathy. During the progression of kidney disease, Ca²⁺ signaling plays key roles in various cell activities such as necrosis, apoptosis, eryptosis and autophagy. Importantly, there are complex Ca²⁺ flux networks between the endoplasmic reticulum (ER), mitochondria and lysosomes which regulate intracellular Ca²⁺ signaling in renal cells and contribute to kidney disease. In addition, Ca²⁺ signaling also links the crosstalk between various cell deaths and autophagy under the stress of heavy metals or high glucose. In this regard, we present a review of Ca²⁺ signaling in cell death and crosstalk with autophagy and its potential as a therapeutic target for the development of new and efficient drugs against kidney diseases.

Transcription profiling of cadmium-exposed livers reveals alteration of lipid metabolism and predisposition to hepatic steatosis

1. Cadmium (Cd) is a ubiquitous environmental toxicant that can cause liver steatosis and nonalcoholic fatty liver disease (NAFLD) on long-term exposure.2. Sixteen Sprague Dawley rats were randomly divided into two groups, and were administered normal saline and 5 mg/(kg·d) cadmium chloride by gavage. In vitro, BRL3A cells, a rat normal liver cell line, were treated with different concentrations of Cd to verify the sequencing results.3. The RNA-seq revealed 146 upregulated genes and 127 downregulated genes in the Cd intervention group. The key genes of lipid metabolism were significantly overexpressed, such as Cyp1a1 and Pla2g2d. The GO enrichment analysis showed that the 'sterol biosynthetic process' was the most obvious difference. The KEGG analysis showed that six of the top 10 differential pathways were related to lipid metabolism. The expression of the essential genes in BRL3A was consistent with the sequencing results. The protein-protein interaction (PPI) yielded that Cyp1a1 is in the central region of the differentially expressed gene network.4. The chronic Cd exposure is still an important environmental health problem with a probable tendency to cause NAFLD. It may possibly act by affecting the lipid metabolism in the liver, especially the synthesis and decomposition of unsaturated fatty acids.

Persistent activation of Nrf2 promotes a vicious cycle of oxidative stress and autophagy inhibition in cadmium-induced kidney injury

Nuclear factor erythroid 2-related factor 2 (Nrf2) serves as the master regulator of antioxidant signaling and inhibition or hyperactivation of Nrf2 pathway will result in the redox imbalance to induce tissue injury. Herein, we established cadmium (Cd)-exposed rat kidney injury model by intraperitoneal injection with CdCl₂ (1.5 mg/kg body weight) and cytotoxicity model of NRK-52E cells by CdCl₂ (5 μM) exposure to reveal the role of Nrf2 hyperactivation in Cd-induced nephrotoxicity. Data from the in vitro and in vivo study showed that Cd caused Nrf2 nuclear retention due to nuclear-cytoplasmic depletion of Kelch-like ECH-associated protein 1 (Keap1) and Sequestosome-1(SQSTM1/p62) accumulation, leading to the persistent activation of Nrf2. Moreover, we established inhibited models of Cd-induced prolonged Nrf2 activation using siRNA-mediated gene silencing in vitro and pharmacological inhibition in vivo for subsequent assays. First, Cd-induced cytotoxicity, renal injury and concomitant oxidative stress were markedly alleviated by Nrf2 inhibition. Second, Cd-induced autophagy inhibition was notably alleviated by Nrf2 inhibition. Further, we revealed underlying molecular mechanisms of the crosstalk between persistent activation of Nrf2 and autophagy inhibition in Cd-induced nephrotoxicity. Data showed that Cd-induced lysosomal dysfunction evidenced by impaired lysosomal biogenesis and degradation capacity was markedly recovered by Nrf2 inhibition. Meanwhile, Cd-impaired autophagosome-lysosome fusion was obviously restored by Nrf2 inhibition. In conclusion, our findings revealed that persistent activation of Nrf2 promoted a vicious cycle of oxidative stress and autophagy inhibition in Cd-induced nephrotoxicity.

Protective effects of selenium yeast against cadmium-induced necroptosis through miR-26a-5p/PTEN/PI3K/AKT signaling pathway in chicken kidney

Cadmium (Cd) is a ubiquitous environmental pollutant of increasing worldwide concern to both humans and animals. Selenium yeast (Se-Y) is an organic selenium source that has been shown an advantage in antagonizing Cd-induced liver necroptosis in chicken. Herein, we described the discovery path of Se-Y antagonism in Cd-induced renal necroptosis in chicken through targeting miR-26a-5p/PTEN/PI3K/AKT signaling pathway. We set up four groups of chickens at random: control group (0.5 mg/kg Na₂SeO₃), Se-Y group (0.5 mg/kg Se-Y), Se-Y+Cd group (0.5 mg/kg Se-Y and 150 mg/kg CdCl₂) and Cd group (150 mg/kg CdCl₂ and 0.5 mg/kg Na₂SeO₃). Interestingly, we found Se-Y, but not Na₂SeO₃, significantly blocked Cd accumulation in the kidney and alleviated Cd-induced necroptosis through inhibiting the expression of RIP1, RIP3 and MLKL. Se-Y, activated miR-26a-5p expression, thereby down-regulated the expression of PTEN, resulting in the up-regulation of PI3K/AKT signaling pathway and the inhibition of oxidative stress in both Se-Y and Cd treated chickens. Besides that, Se-Y could also specifically reduce the expression levels of heat shock protein 60 (HSP60), HSP70 and HSP90 in Se-Y and Cd co-treated chickens. Taken together, our results showed that Se-Y has an added value to antagonize Cd-induced necroptosis in chicken kidney by regulating the miR-26a-5p/PTEN/PI3K/AKT signaling pathway and HSPs, indicating that Se-Y could serve as an effective antagonist on Cd-induced renal necroptosis in chickens.

MiR-34a/Sirt1/p53 signaling pathway contributes to cadmium-induced nephrotoxicity: A preclinical study in mice

Cadmium (Cd), as an environmental pollutant, can lead to nephrotoxicity. However, its nephrotoxicological mechanisms have not been fully elucidated. In this study, Cd (1.5 mg/kg body weight, gavaged for 4 weeks) was found to induce the renal damage in mice, based on indicators including Cd concentration, kidney index, serum creatinine and blood urea nitrogen levels, pro-inflammatory cytokines and their mRNA expressions, levels of Bcl-2, Bax and caspase9, and histopathological changes of the kidneys. Furthermore, Cd-caused detrimental changes through inducing inflammation and apoptosis via the miR-34a/Sirt1/p53 axis. This is the first report on the role of miR-34a/Sirt1/p53 axis in regulating Cd-caused apoptosis and nephrotoxicity in mice. The findings obtained in this study provide new insights into miRNA-based regulation of heavy metal induced-nephrotoxicity.

Dysregulation of autophagy acts as a pathogenic mechanism of non-alcoholic fatty liver disease (NAFLD) induced by common environmental pollutants

Non-alcoholic fatty liver disease (NAFLD) has been the most common chronic liver disease in the world, including the developing countries. NAFLD is metabolic disease with significant lipid deposition in the hepatocytes of the liver, which is usually associated with oxidative stress, inflammation and fibrogenesis, and insulin resistance. Progressive NAFLD can develop into non-alcoholic steatohepatitis (NASH) or hepatocellular carcinoma. The current evidence proposes that environmental pollutants promote development and progression of NAFLD, and autophagy plays a vital role but is multifactorial affected in NAFLD. In this review, we analyzed on the regulations of common environmental pollutants on autophagy in NAFLD. To clarify the involved roles of autophagy, we discussed the dysregulation of autophagy by environmental pollutants in adipose tissue and gut, and their interactions with liver, as well as epigenetic regulation on autophagy by environmental pollutants. Furthermore, protective roles of potential therapeutic treatments on the multiple-hits of autophagy in NAFLD were descripted.

Reproductive toxicity of cadmium in pubertal male rats induced by cell apoptosis

Cadmium (Cd) is a heavy metal that is widely present in modern industrial production. It is a known, highly toxic environmental endocrine disruptor. Long-term exposure to Cd can cause varying degrees of damage to the liver, kidney, and reproductive system of organisms, especially the male reproductive system. This study aimed to explore the mechanism of Cd toxicity in the male reproductive system during puberty. Eighteen healthy 6-week-old male Sprague-Dawley rats were randomly divided into three groups (control group, low-dose group, and high-dose group) according to their body weight, with six in each group. Cd (0, 1, and 3 mg/kg/day) was given by gavage for 28 consecutive days. The results showed that Cd exposure to each dose group caused a decrease in the testicular organ coefficient and sperm count, compared with the control group. Cd exposure resulted in significant changes in testicular morphology in the 3 mg/kg/day Cd group. In the 1 and 3 mg/kg/day Cd groups, serum testosterone decreased and apoptosis of testicular cells increased significantly (p < 0.05). In addition, compared with the control group, the activity of glutathione peroxidase and superoxide dismutase in each Cd exposure dose group decreased, but the content of malondialdehyde in the high-dose, 3 mg/kg/day Cd treatment group significantly increased (p < 0.05). Although Cd exposure caused an increase in the messenger RNA (mRNA) levels of Bcl-2, Caspase-3 and Caspase-9 in the testicular tissues (p < 0.05), Bcl-2 expression was unchanged (p > 0.05). The expression level of Akt mRNA in testicular tissue of rats in the high-dose 3 mg/kg/day Cd group was increased (p < 0.05). Our data suggest that Cd affected testosterone levels, and apoptosis was observed in spermatids.

Exploration of the optimal strategy for dietary calcium intervention against the toxicity of liver and kidney induced by cadmium in mice: An in vivo diet intervention study

Cadmium (Cd) is a toxic non-essential element, while calcium (Ca) is an essential element with high chemical similarity to Cd. Dietary intake is the major Cd exposure pathway for non-smokers. A multi-concentration dietary intervention experiment was designed to explore the optimum concentration of Ca in diet with obvious protective effects against the toxicity of livers and kidneys induced by Cd in mice. The mice were divided into six groups with different concentrations of Cd and Ca in their food: control-group (no Cd or Ca), Ca-group (100 g/kg Ca, without Cd), Cd-group (2 mg/kg Cd, without Ca), Ca_L+Cd-group (2 mg/kg Cd, 2 g/kg Ca), Ca_M+Cd-group (2 mg/kg Cd, 20 g/kg Ca) and Ca_H+Cd-group (2 mg/kg Cd, 100 g/kg Ca). The organ indexes, oxidative stress biomarkers, lesions and Cd concentrations were detected after a 30-day exposure period. Results showed that serum Aspartate Aminotransferase (AST) level in Ca_H+Cd-group was significantly lower than that in Cd-group, while close to that in control-group. The contents of Serum Blood Urea Nitrogen (BUN) in different groups showed the same trend. Concentrations of all oxidative stress biomarkers (GSH-Px, SOD, CAT, GSH and MDA) in Ca_H+Cd-group were close to the normal levels of control-group while significantly different from those in Cd-group. The only exception was the Malondialdehyde (MDA) levels in kidneys. This study suggests that Ca plays a protective role in relieving the Cd-induced toxicity of livers and kidneys and a concentration of 100 g/kg for Ca in diet showed the best protective effects. These findings could provide a clue for further studies concerning human diet intervention for Cd control.

Nephrotoxicity Profile of Cadmium Revealed by Proteomics in Mouse Kidney

Cadmium (Cd) is a highly toxic metal and kidney is its main target. However, the molecular effects and associated potential impacts of Cd-accumulated kidney have not been well investigated. In this study, mouse was used as a model to investigate the Cd-induced proteomic profile change in kidney, and a total of 34 differentially expressed proteins were detected by two-dimensional gel electrophoresis (2-DE) and further identified by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). Through Gene Ontology analysis and KEGG pathway annotation, it showed that Cd-regulated kidney metabolism and promoted renal damage and cell migration. By validation of Western blotting and RT-qPCR, metastasis-related proteins LIM and SH3 domain protein 1 (LASP1) and phosphoenolpyruvate carboxykinase/cytosolic [GTP] (PEPCK1) were confirmed to be upregulated; Acyl-CoA synthetase medium-chain family member 3 (ACSM3) was downregulated. Furthermore, carcinoma development-related proteins initiation factor 4A (eIF4A) and pyridoxine-5'-phosphate oxidase (PNPO) were upregulated, and pyridoxal kinase (PK) was downregulated. The downregulation of Na(+)/H(+) exchange regulatory cofactor (NHERF3) might promote renal damage which associated with decrease of transferrin (TRF) in kidney. Taken together, our results revealed proteomic profile of Cd-induced nephrotoxicity and provided data for further insights into the mechanisms of Cd toxicity.

The calcimimetic R-568 attenuates subarachnoid hemorrhage-induced vasospasm through PI3K/Akt/eNOS signaling pathway in the rat model

Cerebral vasospasm (CVS) causes mortality and morbidity in patients after subarachnoid hemorrhage (SAH). The mechanism and adequate treatment of CVS are still elusive. R-568 is a calcimimetic agent known to exert a vasodilating effect. However, there is no report on its vasodilator effect against SAH-induced vasospasm. In the present study, we investigated the therapeutic effect of R-568 on the SAH-induced CVS model in rats. Seventy-two adult male Sprague-Dawley rats were divided into 8 groups: sham surgery; SAH only; SAH + Vehicle, SAH + R-568; SAH + R-568 + Wortmannin (the PI3K inhibitor); SAH + Wortmannin; SAH + R-568 + Calhex-231 (a calcilytic agent); SAH + Calhex-231. SAH was induced by blood (0.3 mL) given by intracisternal injection. R-568 (20 µM) was administered intracisternal immediately prior to experimental SAH. Basilar arteries (BAs) were obtained to evaluate PI3K/Akt/eNOS pathway (immunoblotting) and morphological changes 48 h after SAH. Perimeters of BAs were decreased by 24.1% in the SAH group compared to the control group and the wall thickness was increased by 75.3%. With R-568 treatment, those percentages were 9.6% and 29.6%, respectively, indicating that vasospasm was considerably improved when compared with the SAH group (P < 0.001 in both). While p-PI3K/PI3K and p-Akt/Akt ratio and eNOS protein expression were markedly decreased in the SAH rats, treatment with R-568 resulted in a significant increase in these levels. The beneficial effects of R-568 were partially blocked in the presence of Calhex-231 and completely blocked in the presence of Wortmannin. Herein, we found that treatment with R-568 would attenuate SAH-induced CVS through the PI3K/Akt/eNOS pathway and demonstrate therapeutic promise in CVS treatment following SAH.

Puerarin Restores Autophagosome-Lysosome Fusion to Alleviate Cadmium-Induced Autophagy Blockade via Restoring the Expression of Rab7 in Hepatocytes

Autophagic dysfunction is one of the main mechanisms by which the environmental pollutant cadmium (Cd) induces cell injury. Puerarin (Pue, a monomeric Chinese herbal medicine extract) has been reported to alleviate Cd-induced cell injury by regulating autophagy pathways; however, its detailed mechanisms are unclear. In the present study, to investigate the detailed mechanisms by which Pue targets autophagy to alleviate Cd hepatotoxicity, alpha mouse liver 12 (AML12) cells were used to construct a model of Cd-induced hepatocyte injury in vitro. First, the protective effect of Pue on Cd-induced cell injury was confirmed by changes in cell proliferation, cell morphology, and cell ultrastructure. Next, we found that Pue activated autophagy and mitigated Cd-induced autophagy blockade. In this process, the lysosome was further activated and the lysosomal degradation capacity was strengthened. We also found that Pue restored the autophagosome-lysosome fusion and the expression of Rab7 in Cd-exposed hepatocytes. However, the fusion of autophagosomes with lysosomes and autophagic flux were inhibited after knocking down Rab7, and were further inhibited after combined treatment with Cd. In addition, after knocking down Rab7, the protective effects of Pue on restoring autophagosome-lysosome fusion and alleviating autophagy blockade in Cd-exposed cells were inhibited. In conclusion, Pue-mediated alleviation of Cd-induced hepatocyte injury was related to the activation of autophagy and the alleviation of autophagy blockade. Pue also restored the fusion of autophagosomes and lysosomes by restoring the protein expression of Rab7, thereby alleviating Cd-induced autophagy blockade in hepatocytes.

Cadmium induces epithelial-mesenchymal transition and migration of renal cancer cells by increasing PGE2 through a cAMP/PKA-COX2 dependent mechanism

Environmental or occupational exposure of Cadmium (Cd) is concerned to be a threat to human health. The kidney is main target of Cd accumulation, which increases the risk of renal cell carcinoma (RCC). In addition, low content of Cd had been determined in kidney cancer, however, the roles of presence of Cd in renal tumors progression are still unclear. The present study is proposed to determine the effect of low-dose Cd exposure on the renal cancer cells and aimed to clarify the underlying mechanisms. The cell viability, cytotoxicity, and the migratory effect of low-dose Cd on the renal cancer cells were detected. Moreover, the roles of reactive oxygen species (ROS), Ca²⁺, and cyclic AMP (cAMP)/protein kinase A (PKA)-cyclooxygenase2 (COX2) signaling, as well as COX2 catalytic product prostaglandin E2 (PGE2) on cell migration and invasion were identified. Our results suggested that low dose Cd exposure promoted migration of renal cancer Caki-1 cells, which was not dependent on Cd-induced ROS and intracellular Ca²⁺ levels. Cd exposure induced cAMP/PKA-COX2, which mediated cell migration and invasion, and decreased expressions of epithelial-mesenchymal transition (EMT) marker, E-cadherin, but increased expressions of N-cadherin and Vimentin. Moreover, Cd-induced secretion of PGE2 feedback on activation of cAMP/PKA-COX2 signaling, also promoted EMT, migration and invasion of renal cancer Caki-1 cells. This study might contribute to understanding of the mechanism of Cd-induce progression of renal cancer and future studies on the prevention and therapy of renal cell carcinomas.

Inhibition of autophagy enhances cadmium-induced apoptosis in duck renal tubular epithelial cells

Increasing evidence indicates autophagy and apoptosis are involved in the toxicity mechanism of heavy metals. Our previous studies showed that cadmium (Cd) could induce autophagy and apoptosis in duck kidneys in vivo, nevertheless, the interaction between them has yet to be elucidated. Herein, the cells were either treated with 3CdSO₄·8H₂O (0, 1.25, 2.5, 5.0 μM Cd) or/and 3-methyladenine (3-MA) (2.5 μM) for 12 h and the indictors related autophagy and apoptosis were detected to assess the correlation between autophagy and apoptosis induced by Cd in duck renal tubular epithelial cells. The results demonstrated that Cd exposure notably elevated intracellular and extracellular Cd contents, the number of autophagosomes and LC3 puncta, up-regulated LC3A, LC3B, Beclin-1, Atg5 mRNA levels, and Beclin-1 and LC3II/LC3I protein levels, down-regulated mTOR, p62 and Dynein mRNA levels and p62 protein level. Additionally, autophagy inhibitor 3-MA decreased Beclin-1, LC3II/LC3I protein levels and increased p62 protein level. Moreover, co-treatment with Cd and 3-MA could notably elevate Caspase-3, Cyt C, Bax, and Bak-1 mRNA levels, Caspase-3 and cleaved Caspase-3 protein levels, and cell apoptotic rate as well as cell damage, decreased mitochondrial membrane potential (MMP), Bcl-2 mRNA level and the ratio of Bcl-2 to Bax compared to treatment with Cd alone. Overall, these results indicate Cd exposure can induce autophagy in duck renal tubular epithelial cells, and inhibition of autophagy might aggravate Cd-induced apoptosis through mitochondria-mediated pathway.

Endoplasmic reticulum stress and autophagy contributed to cadmium nephrotoxicity in HK-2 cells and Sprague-Dawley rats

Excessive accumulation of cadmium is known to cause nephrotoxicity by targeting renal proximal tubular epithelial cells. Studies showed an essential role of autophagy in cadmium-induced nephrotoxicity; however, its underlying mechanisms accompanied by autophagy are incompletely understood. Using an HK-2 human renal proximal tubular epithelial cell line as a study model, sustained exposure of cadmium chloride (CdCl₂) was shown to cause cell viability loss, which was alleviated by inhibitors of autophagy but not apoptosis. Data from molecular and biochemical studies revealed an induction of autophagy proteins, intracellular acidic vesicles, and autophagic flux in CdCl₂-treated cells. However, there was little sign of apoptosis-related changes. Pharmacological and genetic studies indicated an elevation of Endoplasmic Reticulum (ER) stress, Forkhead Box Class O (FoxO3a), Bcl-2 Interacting Protein 3 (Bnip3), and Beclin1, as well as their involvement in cadmium-induced autophagy and autophagic cell death. Renal injury, histological changes, and molecular marker of ER stress, FoxO3a, Bnip3, and autophagy were observed in the kidney cortex of CdCl₂-exposed Sprague-Dawley rats. These observations indicate that ER stress, FoxO3a, Bnip3, and autophagy signaling were actively involved in cadmium-induced nephrotoxicity. Additionally, FoxO3a may act as a linking molecule to convey ER stress signals to Bnip3 and autophagy machinery upon cadmium exposure.

Delayed treatment with an autophagy inhibitor 3-MA alleviates the progression of hyperuricemic nephropathy

Autophagy is a cell self-renewal process that relies on the degradation of the cytoplasmic proteins or organelles of lysosomes and is associated with development of numerous diseases. However, the therapeutic effect of autophagy inhibition on hyperuricemic nephropathy (HN) and the underlying mechanisms are still unknown. Here, we investigated the effect of delayed treatment with 3-methyladenine (3-MA), a specific autophagy inhibitor, on the development of HN in a rat model. Administration of 3-MA at 21 days following after uric acid injury protected kidney from hyperuricemic-related injuries, as demonstrated by improving renal dysfunction and architecture damage, blocking Beclin-1 and LC3II/I and decreasing the number of autophagic vacuoles. Late treatment with 3-MA was also effective in attenuating renal fibrosis as evidenced by reducing ECM protein deposition, blocking epithelial-to-mesenchymal transition (EMT) and decreasing the number of renal epithelial cells arrested at the G2/M phase of cell cycle. Injury to the kidney resulted in increased expression of TGFβ receptor I, and phosphorylation of Smad3, 3-MA significantly abrogated all these responses. Moreover, inhibition of autophagy suppressed mitochondrial fission, downregulated the expression of Dynamin-related protein 1 (Drp-1), Cofilin and F-actin, and alleviated cell apoptosis. Finally, 3-MA effectively blocked STAT3 and NF-κB phosphorylation and suppressed infiltration of macrophages and lymphocytes as well as release of multiple profibrogenic cytokines/chemokines in the injured kidney. Taken together, these findings indicate that hyperuricemia-induced autophagy is critically involved in the activation of renal fibroblasts, EMT, mitochondrial fission and apoptosis of tubular epithelial cells and development of renal fibrosis. Thus, this study provides evidence for autophagy inhibitors as the treatment of HN patients.