Selenium Antagonizes the Lead-Induced Apoptosis of Chicken Splenic Lymphocytes In Vitro by Activating the PI3K/Akt Pathway

PI3K/AKT pathway modulation and cold acclimation alleviation concerning apoptosis and necroptosis in broiler thymus

Moderate cold stimulation regulates the thymus's growth and function and facilitates cold acclimatization in broilers. However, the underlying mechanism remains unknown. To explore the possible mechanism of the thymus in cold-acclimated broilers against cold stress, 240 one-day-old Arbor Acres (AA) broilers were assigned to 2 groups randomly. The control group (C) was housed at conventional temperatures. The temperature during the first week was 33°C to 34°C. Between the ages of 8 and 32 d, the temperature was lowered by 1°C every 2 d, i.e., gradually from 32°C to 20°C, and then maintained at 20°C until 42 d of age. The cold-acclimated group (C-3) was housed at the same temperature as C from 1 to 7 d after birth. Between 8 and 42 d, the temperature of C-3 was 3°C colder than C. After 24 h exposure to acute cold stress (ACS) at 42 d, C and C-3 were named as S and S-3. The results showed that ACS was able to induce oxidation stress, modulate PI3K/AKT signal, and cause necroptosis and apoptosis in broiler thymus. By contrast, cold acclimation could alleviate apoptosis and necroptosis induced by cold stress via alleviating oxidative stress, efficiently activating the PI3K/AKT signal, as well as decreasing apoptotic and necrotic genes' levels. This study offers a novel theoretical basis for cold acclimation to improve the body's cold tolerance.

The effect of selenium on the proliferation of bovine endometrial epithelial cells in a lipopolysaccharide-induced damage model

BACKGROUND

Endometritis is a common bovine postpartum disease. Rapid endometrial repair is beneficial for forming natural defense barriers and lets cows enter the next breeding cycle as soon as possible. Selenium (Se) is an essential trace element closely related to growth and development in animals. This study aims to observe the effect of Se on the proliferation of bovine endometrial epithelial cells (BEECs) induced by lipopolysaccharide (LPS) and to elucidate the possible underlying mechanism.

RESULTS

In this study, we developed a BEECs damage model using LPS. Flow cytometry, cell scratch test and EdU proliferation assay were used to evaluate the cell cycle, migration and proliferation. The mRNA transcriptions of growth factors were detected by quantitative reverse transcription-polymerase chain reaction. The activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) and Wnt/β-catenin pathways were detected by Western blotting and immunofluorescence. The results showed that the cell viability and BCL-2/BAX protein ratio were significantly decreased, and the cell apoptosis rate was significantly increased in the LPS group. Compared with the LPS group, Se promoted cell cycle progression, increased cell migration and proliferation, and significantly increased the gene expressions of TGFB1, TGFB3 and VEGFA. Se decreased the BCL-2/BAX protein ratio, promoted β-catenin translocation from the cytoplasm to the nucleus and activated the Wnt/β-catenin and PI3K/AKT signaling pathways inhibited by LPS.

CONCLUSIONS

In conclusion, Se can attenuate LPS-induced damage to BEECs and promote cell proliferation and migration in vitro by enhancing growth factors gene expression and activating the PI3K/AKT and Wnt/β-catenin signaling pathways.

Insights into the mechanism of transcription factors in Pb2+-induced apoptosis

The health risks associated with exposure to heavy metals, such as Pb2+, are increasingly concerning the public. Pb2+ can cause significant harm to the human body through oxidative stress, autophagy, inflammation, and DNA damage, disrupting cellular homeostasis and ultimately leading to cell death. Among these mechanisms, apoptosis is considered crucial. It has been confirmed that transcription factors play a central role as mediators during the apoptosis process. Interestingly, these transcription factors have different effects on apoptosis depending on the concentration and duration of Pb2+ exposure. In this article, we systematically summarize the significant roles of several transcription factors in Pb2+-induced apoptosis. This information provides insights into therapeutic strategies and prognostic biomarkers for diseases related to Pb2+ exposure.

Zinc Inhibits Lead-Induced Oxidative Stress and Apoptosis of ST Cells Through ROS/PTEN/PI3K/AKT Axis

Lead (Pb) is a widely distributed toxic heavy metal element known to have strong male reproductive toxicity, which can result in issues such as abnormal count and morphology of sperm. Zinc (Zn) is an essential trace element for the human body that can antagonize the activity of Pb in some physiological environments, and it also possesses antioxidant and anti-inflammatory effects. However, the specific mechanism of Zn's antagonism against Pb remains largely unclear. In our study, we conducted research using swine testis cells (ST cells) and confirmed that the half maximal inhibitory concentration of Pb on ST cells was 994.4 μM, and the optimal antagonistic concentration of Zn was 10 μM. Based on this information, we treated ST cells with Pb and Zn and detected related indices such as apoptosis, oxidative stress, and the PTEN/PI3K/AKT pathway using flow cytometry, DCFH-DA staining, RT-PCR, and Western blot. Our results demonstrated that Pb exposure can generate excessive reactive oxygen species (ROS), disrupt the antioxidant system, upregulate PTEN expression, and inhibit the PI3K/AKT pathway in ST cells. In contrast, Zn significantly inhibited the overproduction of ROS, improved oxidative stress, and decreased PTEN expression, thus protecting the PI3K/AKT pathway compared to Pb-exposed ST cells. Furthermore, we found that Pb exposure exacerbated the expression of genes related to the apoptosis pathway and reduced the expression of anti-apoptotic genes. Furthermore, this situation was significantly improved when co-cultured with Pb and Zn. In summary, our study demonstrated that Zn alleviated Pb-induced oxidative stress and apoptosis through the ROS/PTEN/PI3K/AKT axis in ST cells.

Identification of the Hub Genes Linked to Lead (IV)-Induced Spleen Toxicity Using the Rat Model

Exposure to lead (Pb) has harmful effects on the organs of both humans and animals, particularly the spleen. However, the precise mechanisms through which Pb (IV) exposure leads to spleen toxicity remain unclear. Hence, this study aimed to identify the key genes and signaling pathways involved in spleen toxicity caused by Pb (IV) incubation. We obtained the dataset GSE59925 from the Gene Expression Omnibus, which included spleen samples treated with lead tetraacetate (PbAc4) as well as control samples on the 1st and 5th day. Through differential expression analysis, we identified 607 and 704 differentially expressed genes (DEGs) in the spleens on the 1st and 5th day following PbAc4 treatment, respectively, with 245 overlapping DEGs between the two time points. Gene ontology analysis revealed that the commonly shared DEGs were primarily involved in signal transduction, drug response, cell proliferation, adhesion, and migration. Pathway analysis indicated that the common DEGs were primarily associated with MAPK, TNF, cAMP, Hippo, and TGF-β signaling pathways. Furthermore, we identified the hub genes such as CXCL10, PARP1, APOE, and VDR contributing to PbAc4-induced spleen toxicity. This study enhances our understanding of the molecular mechanisms underlying Pb (IV) toxicity in the spleen.

Profile of N6-methyladenosine of Pb-exposed neurons presents epitranscriptomic alterations in PI3K-AKT pathway-associated genes

Lead (Pb) is a pervasive heavy metal with multi-organ toxicity. However, the molecular mechanisms of Pb-induced neurotoxicity are not fully understood. The dynamics of N6-methylademine (m6A) is an emerging regulatory mechanism for gene expression, which is closely related to nervous system diseases. To elucidate the association between m6A modification and Pb-mediated neurotoxicity, primary hippocampal neurons exposed to 5 μM Pb for 48 h were used as the paradigm neurotoxic model in this study. According to the results, Pb exposure reprogrammed the transcription spectrum. Simultaneously, Pb exposure remodeled the transcriptome-wide distribution of m6A while disrupting the overall level of m6A in cellular transcripts. United analysis of MeRIP-Seq and RNA-Seq was applied to further identify the core genes whose expression levels are regulated by m6A in the process of lead-induced nerve injury. GO and KEGG analysis unveiled that the modified transcripts were overrepresented by the PI3K-AKT pathway. Mechanically, we elucidated the regulatory role of the methyltransferase like3 (METTL3) in the process of lead-induced neurotoxicity and the downregulation of the PI3K-AKT pathway. In conclusion, our novel findings shed new light on the functional roles of m6A modification in the expressional alternations of downstream transcripts caused by lead, providing an innovative molecular basis to explain Pb neurotoxicity.

Toxicity of Glycyl-l-Prolyl-l-Glutamate Pseudotripeptides: Cytotoxic, Oxidative, Genotoxic, and Embryotoxic Perspectives

The tripeptide H-Gly-Pro-Glu-OH (GPE) and its analogs began to take much interest from scientists for developing effective novel molecules in the treatment of several disorders including Alzheimer’s disease, Parkinson’s disease, and stroke. The peptidomimetics of GPEs exerted significant biological properties involving anti-inflammatory, antiapoptotic, and anticancer properties. The assessments of their hematological toxicity potentials are critically required for their possible usage in further preclinical and clinical trials against a wide range of pathological conditions. However, there is so limited information on the safety profiling of GPE and its analogs on human blood tissue from cytotoxic, oxidative, and genotoxic perspectives. And, their embryotoxicity potentials were not investigated yet. Therefore, in this study, measurements of mitochondrial viability (using MTT assay) and lactate dehydrogenase (LDH) release as well as total antioxidant capacity (TAC) assays were performed on cultured human whole blood cells after treatment with GPE and its three novel peptidomimetics for 72 h. Sister chromatid exchange (SCE), micronucleus (MN), and 8-oxo-2-deoxyguanosine (8-OH-dG) assays were performed for determining the genotoxic damage potentials. In addition, the nuclear division index (NDI) was figured out for revealing their cytostatic potentials. Embryotoxicity assessments were performed on cultured human pluripotent NT2 embryonal carcinoma cells by MTT and LDH assays. The present results from cytotoxicity, oxidative, genotoxicity, and embryotoxicity testing clearly propounded that GPEs had good biosafety profiles and were trouble-free from the toxicological point of view. Noncytotoxic, antioxidative, nongenotoxic, noncytostatic, and nonembryotoxic features of GPE analogs are worthwhile exploring further and may exert high potentials for improving the development of novel disease-modifying agents.

3D cell culture based on artificial cells and hydrogel under microgravity for bottom-up microtissue constructs

The use of hydrogel as a filling medium to recombine dispersed microencapsulated cells to form an embedded gel-cell microcapsule complex is a new idea based on bottom-up tissue construction, which is benefit for cell distribution and of great significance for tissue construction research in vitro. In this experiment, sodium alginate and chitosan were used as the main materials, rat normal liver cell BRL-3A was used as the model cell to prepare “artificial cells”. Silkworm pupa was used as raw material to extract silk fibroin solution, which was prepared by ultrasound to be the silk fibroin gel; silk fibroin hydrogel-microencapsulated hepatocyte embedded complex was then prepared by using silk fibroin gel as filling medium; the complex was cultured under three modes (static, shaking, and 3D microgravity), and the tissue forming ability of rat hepatocytes was investigated. The results showed that the microgravity culture condition can enhance the cell proliferation and promote the formation of cell colonies in the microcapsules; silk fibroin can form an embedded gel-cell microcapsule complex with microencapsulated cells, which provided mechanical support for the structure of the composite. We hope that this bottom-up construction system will have potential applications in the fields of cell culture and tissue construction.

Aberrant Gene Expression of Selenoproteins in Chicken Spleen Lymphocytes Induced by Mercuric Chloride

Mercury (Hg) is a heavy metal widely distributed in ecological environment, poisoning the immune system of humans and animals. Selenium (Se) is an essential microelement and selenoproteins involved in the procedure of Se antagonizing organ toxicity induced by heavy metals. The aim of this research was to investigate the changes of gene expression profile of selenoproteins induced by mercuric chloride (HgCl₂) in chicken spleen lymphocytes. We established cytotoxicity model of chicken spleen lymphocytes by HgCl₂ exposure, the messenger RNA (mRNA) expression levels of 25 selenoproteins in spleen lymphocytes were analyzed by real-time quantitative PCR (qPCR), and the gene expression pattern of selenoproteins was revealed by principal component analysis (PCA). The results showed that the mRNA expression levels of 13 selenoproteins (GPX3, GPX4, TXNRD2, TXNRD3, DIO2, SELENOS, SELENON, SELENOT, SELENOO, SELENOP, SELENOP2, MSRB1, and SEPHS2) were decreased in HgCl₂ treatment group, and there was strong positive correlation between these selenoproteins and component 1 as well as component 2 of the PCA. At the same time, the protein expression levels of GPX4, TXNRD1, TXNRD2, SELENOM, SELENOS, and SELENON were detected by Western blotting, which were consistent with the changes of gene expression. The results showed that the expression levels of selenoproteins were aberrant in response to HgCl₂ toxicity. The information presented in this study provided clues for further research on the interaction between HgCl₂ and selenoproteins, and the possible mechanism of immune organ toxicity induced by HgCl₂.

Selenium-Enriched Yeast Relieves Hexavalent Chromium Toxicity by Inhibiting NF-κB Signaling Pathway in Broiler Spleens

Simple Summary

Hexavalent chromium is a common environmental pollution. It has been reported that hexavalent chromium threatens the health of humans and animals, so it is necessary to develop new, effective mitigation methods. Selenium is an indispensable micronutrient recently shown to be able to resist the toxicity of heavy metals. Selenium-enriched yeast has a high content of total selenium, which has the advantages of a high absorption rate and safety. Potassium dichromate and selenium-enriched yeast were used to construct single hexavalent chromium and combined selenium/hexavalent-chromium-exposed broiler models. Additionally, the ability to relieve the hexavalent chromium toxicity of selenium along with the molecular mechanisms focusing on inflammation induced by the NF-κB signaling pathway was investigated in this study. Histopathological assessment, serum biochemical tests, oxidative stress kits, enzyme-linked immunosorbent assay, quantitative real-time PCR, and Western blotting were used to detect indicators. We found that the oxidative stress induced by hexavalent chromium triggers NF-κB pathway-driven inflammatory responses in the broiler spleen and further reduces the immune function of broilers. Selenium-enriched yeast protects the spleen from the toxicity of hexavalent chromium exposure through inhibiting the NF-κB signaling pathway.

Abstract

This study was conducted to investigate the molecular mechanisms of selenium (Se) antagonism of hexavalent chromium (Cr⁶⁺)-induced toxicity. Potassium dichromate (K₂Cr₂O₇) and selenium-enriched yeast (SeY) were used to construct the single Cr⁶⁺ and combined Se/Cr⁶⁺ exposure broiler models, and then the broilers were randomly divided into four groups (C group, Se group, Se/Cr⁶⁺ group, and Cr⁶⁺ group). After a 42-day experiment, the spleen tissues of broilers were excised and weighted. The antagonistic mechanisms of Se and Cr⁶⁺ were evaluated using histopathological assessment, serum biochemical tests, oxidative stress kits, ELISA, qPCR, and Western blotting. On the whole, there were no significant changes between the C and Se groups. The spleen organ index in the Cr⁶⁺ group was significantly decreased, but SeY increased spleen organ index to a certain extent. The levels of SOD and GSH were reduced, and the MDA content was elevated by Cr⁶⁺; however, these changes were mitigated by Se/Cr⁶⁺ exposure. Importantly, Cr⁶⁺ exposure induced a series of histopathological injuries in broiler spleen tissues, while these symptoms were significantly relieved in the Se/Cr⁶⁺group. Furthermore, Cr⁶⁺ significantly decreased the levels of T-globulin, IgA, IgM, and IgG in serum. Contrarily, dramatically more T-globulin IgA, IgM, and IgG were found in the Se/Cr⁶⁺group than in the Cr⁶⁺ group. Revealed by the results of qPCR and WB, the expressions of NF-κB, IκBα, and p-IκBα were upregulated in Cr⁶⁺ groups, while they were downregulated in Se/Cr⁶⁺ group compared to that in Cr⁶⁺ group. Besides IFN-γ and IL-2, the expressions of pro-inflammatory cytokines were significantly increased by Cr⁶⁺ exposure, but the SeY supplement relived the expression levels mediated by Cr⁶⁺ exposure. In conclusion, our findings suggest SeY has biological activity that can protect broiler spleens from immunosuppression and inflammation induced by Cr⁶⁺, and we speculate that the NF-κB signaling pathway is one of its mechanisms.

Extracorporeal Cardiac Shock Waves Therapy Improves the Function of Endothelial Progenitor Cells After Hypoxia Injury via Activating PI3K/Akt/eNOS Signal Pathway

Background: Extracorporeal cardiac shock waves (ECSW) have great potential in the treatment of coronary heart disease. Endothelial progenitor cells (EPCs) are a class of pluripotent progenitor cells derived from bone marrow or peripheral blood, which have the capacity to migrate to ischemic myocardium and differentiate into mature endothelial cells and play an important role in neovascularization and endothelial repair. In this study, we investigated whether ECSW therapy can improve EPCs dysfunction and apoptosis induced by hypoxia and explored the underlying mechanisms.

Methods: EPCs were separated from ApoE gene knockout rat bone marrow and identified using flow cytometry and fluorescence staining. EPCs were used to produce in vitro hypoxia-injury models which were then divided into six groups: Control, Hypoxia, Hypoxia + ECSW, Hypoxia + LY294002 + ECSW, Hypoxia + MK-2206 + ECSW, and Hypoxia + L-NAME + ECSW. EPCs from the Control, Hypoxia, and Hypoxia + ECSW groups were used in mRNA sequencing reactions. mRNA and protein expression levels were analyzed using qRT-PCR and western blot analysis, respectively. Proliferation, apoptosis, adhesion, migration, and angiogenesis were measured using CCK-8, flow cytometry, gelatin, transwell, and tube formation, respectively. Nitric oxide (NO) levels were measured using an NO assay kit.

Results: Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis showed that differentially expressed genes were enriched in cancer signaling, PI3K-Akt signaling, and Rap1 signaling pathways. We selected differentially expressed genes in the PI3K-Akt signaling pathway and verified them using a series of experiments. The results showed that ECSW therapy (500 shots at 0.09 mJ/mm²) significantly improved proliferation, adhesion, migration, and tube formation abilities of EPCs following hypoxic injury, accompanied by upregulation of p-PI3K, p-Akt, p-eNOS, Bcl-2 protein and NO, PI3K, and Akt mRNA expression, and downregulation of Bax and Caspase3 protein expression. All these effects of ECSW were eliminated using inhibitors specific to PI3K (LY294002), Akt (MK-2206), and eNOS (L-NAME).

Conclusion: ECSW exerted a strong repaired effect on EPCs suffering inhibited hypoxia injury by inhibiting cell apoptosis and promoting angiogenesis, mainly through activating the PI3K/Akt/eNOS signaling pathway, which provide new evidence for ECSW therapy in CHD.

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.

A potential mechanism associated with lead-induced spermatogonia and Leydig cell toxicity and mitigative effect of selenium in chicken

Lead (Pb) is a toxic heavy metal pollutants and can damage male reproductive function. Selenium (Se) possesses an ability of antagonizing Pb toxicity. However, biological events in the process of Pb toxicity and mitigative effect of Se are not well understood. The aim of present research was to investigate potential mechanism of Se against Pb toxicity from the perspective of oxidative stress, heat shock response and autophagy in the spermatogonia and Leydig cell of chicken. The cells from one-day-old male Hyline chickens were treated with Se (0.5 μmol/L) and/or Pb (20 μmol/L) for 24 h, respectively. Cell viability, cell ultrastucture, Pb and Se concentrations, testosterone level, oxidative stress indicators and relative expression of heat shock proteins (HSPs) and autophagy-related genes were measured. The results showed that spermatogonia was more tolerant to Pb than Leydig cell; cell injury was confirmed via histological assessment, cell viability and testosterone level; oxidative stress was further indicated by the decrease of catalase, glutathione peroxidase, glutathione-s-transferase and superoxide dismutase activities and the increase of malondialdehyde and reactive oxygen species contents. Pb increased expression of HSPs (27, 40, 60, 70 and 90). Meanwhile Pb induced autophagy through up-regulation of autophagy-related proteins 5, Beclin 1, Dynein, light chain 3 (LC3)-I and LC3-II and down-regulation of mammalian target of rapamycin in two type cells of chicken. However, Se intervention mitigated the aforementioned alterations caused by Pb. In conclusion, Pb led to oxidative stress, which triggered heat shock response and autophagy; Se administration mitigated reproductive toxicity of Pb through strengthening antioxidant defense in the spermatogonia and Leydig cell of chicken.

Lead acetate induces apoptosis in Leydig cells by activating PPARγ/caspase-3/PARP pathway

This study was designed to investigate the cytotoxicity of lead acetate (Pb(AC)₂, a representative air pollutant) by focusing on PPARγ/caspase-3/PARP apoptotic signaling pathway and to explore the inhibitory effect of PPARγ antagonist on apoptosis of TM3 Leydig cells. MTT assay was utilized to examine cell viability. Cell apoptosis was analyzed using a flow cytometry by staining with Annexin V-PE/7AAD staining and a fluorescence microscope by staining with Hoechst 33,258. The levels of apoptosis-related proteins were examined using western blot. From the results, Pb reduced significantly TM3 cell proliferation in concentration- and time-dependent manner. It increased significantly apoptosis; increased the PPARγ, Bax, procaspase-3, cleaved caspase-3, proPARP, cleaved PARP levels; and decreased Bcl-2 level in Pb-treated TM3 cells as compared to control cells. Furthermore, pretreatment with PPARγ antagonist significantly attenuated the apoptosis and cleavage of caspase-3 and PARP induced by Pb. Our results suggested that Pb induced cytotoxicity on TM3 Leydig cells, at least in part, by increasing PPARγ expression, stimulating cleavage of caspase-3 and PARP, and then induced cell apoptosis.

Selenium Prevents Lead-Induced Necroptosis by Restoring Antioxidant Functions and Blocking MAPK/NF-κB Pathway in Chicken Lymphocytes

Recent studies have identified a new existence of a genetically programmed and regulated cell death characterized by necrotic cell death morphology, termed necroptosis. Lead (Pb) is a ubiquitously distributed environmental pollutant that is highly toxic to animals and human beings. However, no detailed report has been conducted on the necroptosis in lymphocytes caused by Pb. Selenium (Se), a trace element in the body, has been shown to exert cytoprotective effect in numerous pathological injury caused by heavy metals. Here, lymphocytes isolated from chicken spleen were divided into four groups, control group, Se group, Pb group, and Pb + Se co-treatment group to investigate the potential mechanism in the necroptosis triggered by Pb and in the antagonistic effect of Se on Pb toxicity. Flow cytometry analysis and AO/EB staining showed Pb caused typical necrosis characteristics in the lymphocytes. The expression of RIP1, RIP3, and MLKL was increased, whereas the level of caspase 8 was declined in Pb group, which proved the occurrence of necroptosis. Meanwhile, Pb exposure disrupted the antioxidant enzyme (SOD, GSH-Px, and CAT) balance, promoted the expression of MAPK/NF-κB pathway factors (ERK, JNK, p38, NF-κB, and TNF-α), and activated HSPs (HSP27, HSP40, HSP60, HSP70, and HSP90). However, those Pb-induced changes were significantly alleviated in Se + Pb group. Our study revealed that Pb could trigger lymphocyte necroptosis through MAPK/NF-κB pathway activated by oxidative stress and that Se could antagonize Pb-induced necroptosis in chicken lymphocytes.

Selenium relieves oxidative stress, inflammation, and apoptosis within spleen of chicken exposed to mercuric chloride

Mercuric chloride (HgCl₂) is a widely distributed environmental pollutant with multiorgan toxicity including immune organs such as spleen. Selenium (Se) is an essential trace element in animal nutrition and exerts biological activity to antagonize organ toxicity caused by heavy metals. The objective of this study was to explore the underlying mechanism of the protective effects of Se against spleen damage caused by HgCl₂ in chicken. Ninety male Hyline brown chicken were randomly divided into 3 groups namely Cont, HgCl₂, and HgCl₂+Se group. Chicken were provided with the standard diet and nontreated water, standard diet and HgCl₂-treated water (250 ppm), and sodium selenite-treated diet (10 ppm) plus HgCl₂-treated water (250 ppm), respectively. After being fed for 7 wk, the spleen tissues were collected, and spleen index, the microstructure of the spleen, and the indicators of oxidative stress, inflammation, apoptosis as well as heat shock proteins (HSP) were detected. First, the results of spleen index and pathological examination confirmed that Se exerted an antagonistic effect on the spleen injury induced by HgCl₂. Second, Se ameliorated HgCl₂-induced oxidative stress by decreasing the level of malondialdehyde and increasing the levels of glutathione, glutathione peroxidase, and total antioxidant capacity. Third, Se attenuated HgCl₂-induced inflammation by decreasing the protein expression of nuclear factor kappa-B, inducible nitric oxide synthase, and cyclooxygenase-2, and the gene expression of interleukin (IL)-1β, IL-6, IL-8, IL-12β, IL-18 as well as tumor necrosis factor-α. Fourth, Se inhibited HgCl₂-induced apoptosis by downregulating the protein expression of BCL2 antagonist/killer 1 and upregulating the protein expression of B-cell lymphoma-2. Finally, Se reversed HgCl₂-triggered activation of HSP 60, 70, and 90. In conclusion, Se antagonized HgCl₂-induced spleen damage in chicken, partially through the regulation of oxidative stress, inflammatory, and apoptotic signaling.

Antagonistic effect of selenium on lead-induced neutrophil apoptosis in chickens via miR-16-5p targeting of PiK3R1 and IGF1R

Environmental contamination by heavy metals, such as lead (Pb), can lead to severe immune dysfunction. MicroRNAs (miRNAs) are involved in regulating immunity. Whether Pb can regulate neutrophil apoptosis through miRNA, and whether selenium (Se) can antagonize this response are still unknown. We treated neutrophils with 12.5 μM (CH₃OO)₂Pb and 1 μM Na₂SeO₃ for 3 h, after which apoptosis was evaluated using acrideine orange/ethidium bromide (AO/EB) dual fluorescent staining and flow cytometry. The results showed that neutrophil apoptosis was significantly increased following Pb exposure, and that this response was prevented upon Se addition. Pb up-regulates miR-16-5p and leads to the subsequent down-regulation of the target genes phosphoinositide-3-kinase regulatory subunit 1 (PiK3R1), insulin-like growth factor 1 receptor (IGF1R), and phosphatidylinositol 3 kinase (Pi3K)-protein kinase B (AKT), followed by activation of the tumor protein P53 (P53)-B-cell lymphoma-2 (Bcl-2)/Bcl-2-Associated X protein (Bax)-cytochrome c (Cytc)-Caspase 9 (mitochondrial apoptotic pathway) and the tumor necrosis factor receptor superfamily member 6 (Fas)-Fas-associated death domain protein (Fadd)-Caspase 8 (death receptor pathway). Pb also triggered oxidative stress and indirectly activated the mitochondrial apoptotic pathway. We conclude that miR-16-5p plays a key role in the apoptosis of neutrophils exposed to Pb by down-regulating the expression of PiK3R1 and IGFR1, thereby activating the mitochondrial apoptotic pathway and death receptor pathway. Se can prevent Pb-induced apoptosis.

Malus micromalus Makino phenolic extract preserves hepatorenal function by regulating PKC-α signaling pathway and attenuating endoplasmic reticulum stress in lead (II) exposure mice

Lead (Pb), which widely recognized as a nonessential heavy metal and a major environmental contamination, is a growing threat to the ecosystem and human body. In the present study, Malus micromalus Makino cv. 'Dong Hong' phenolic extract (MMPE) has been used to antagonise Pb-induced erythrocyte injury, hepatic and renal dysfunction in mice. Six-week-old male Kunming mice were gavaged with PbCl₂ (20 mg/kg mouse/day) and/or MMPE (100 mg/kg mouse/day) by gavage administration for 10 days. We evaluated erythrocyte fragility, relative organ mass, biochemical parameters and histopathological changes to evaluate the protection effect of MMPE on the injury of liver and kidney in Pb-treated mice. MMPE significantly inhibited the increase of protein kinase C-α, B-cell lymphoma-2-associated X, cytochrome C and Caspase-3 protein levels and decreased calreticulin protein expression level in Pb-exposed mice. MMPE supplementation could maintain the integrity of erythrocyte membranes and ameliorate the endoplasmic reticulum stress in Pb-treated mice. It suggested MMPE as a natural nutritional supplement to alleviate Pb-induced hazardous effects in Pb-exposed humans.

Selenium-Yeast Alleviated Inflammatory Damage Caused by Lead via Inhibiting Ras/ERK Pathway and Inflammatory Factors in Chicken Skeletal Muscles

The aim of this study was to investigate the ameliorative effects of selenium-enriched yeast (Se-yeast) on the inflammatory damage induced by lead (Pb) in chicken skeletal muscles. A total of 108 1-day-old broiler chickens were randomly allocated into four groups (n = 27/group): the control group (C group), the Se-yeast-supplemented group (Se group), the lead-treated group (Pb group), and finally the Se- and Pb-combined group (Pb/Se group). The C group was fed with a basic diet comprising 0.049 mg/kg Se and 0.1 mg/kg Pb while the Se group was fed a Se-yeast diet containing 0.30 mg/kg Se and 0.1 mg/kg Pb. Similarly, the Pb group was fed a Pb acetate diet containing 0.049 mg/kg Se and 350 mg/kg Pb while the Pb/Se group was fed with a Se-yeast diet containing 0.30 mg/kg Se and 350 mg/kg Pb. On days 7, 21, and 35 after commencing the experiment, nine chicks belonging to each group were euthanized and the samples were analyzed by employing the techniques of inductively coupled plasma mass spectrometry and real-time quantitative PCR, along with Western blotting. The results indicated that excess Pb increased the nitric oxide concentration, enhanced the activity of inducible nitric oxide synthase (iNOS), and the mRNA levels of interleukin 1β (IL-1β), interleukin 4 (IL-4), interleukin 10 (IL-10), and interferon gamma (IFN-γ) in a time-dependent manner. Further, it was found that Se reduced damage caused by Pb by decreasing the expression of inflammatory factors in chicken skeletal muscles. Taken together, the results from this study provide the theoretical basis for an alleviate effect of Se on Pb-induced inflammatory damage in chicken skeletal muscles, mediated by inhibiting the Ras/extracellular signal-regulated kinase (ERK) pathway and the inflammatory factors.

Effect of selenium antagonist lead-induced damage on Th1/Th2 imbalance in the peripheral blood lymphocytes of chickens

Lead (Pb) is a type of toxic metal that can hurt the immune system. Selenium (Se) can reduce the damage caused by heavy metals. To investigate the effects of Se against Pb on bird immune cells, as well as the immunotoxin mechanism of Pb, Se supplementation and/or Pb poisoning chicken models were established. One hundred eighty 1-year-old broiler chickens were randomly divided into four groups (n = 6). The four groups were the control group, the selenium-rich group (Se group), the Pb supplementation group (Pb group) and the Se and Pb compound group (Se + Pb group). The peripheral blood lymphocytes of chickens were collected to test the selenoproteins and cytokine mRNA levels at 30 and 60 d. Determination of the content of Se and Pb in the serum, principal component analysis and ingenuity pathway analysis were performed at the two time points. As a result, Pb exposure increased the content of Pb, activating the Th1/Th2 pathway in peripheral blood lymphocytes. Additionally, this experiment showed that Se supplementation and Pb exposure could influence the mRNA levels of selenoproteins and cytokines in the peripheral blood lymphocytes of chickens. However, all of the parameters that we detected in the experiment indicated that Se supplementation could alleviate the increase of selenoproteins and cytokine mRNA levels and the Th1/Th2 imbalance induced by Pb in peripheral blood lymphocytes. In summary, Se can alleviate the toxic effects caused by Pb in the peripheral blood lymphocytes of chickens, suggesting the antagonism between Se and Pb.

Avian Stress-Related Transcriptome and Selenotranscriptome: Role during Exposure to Heavy Metals and Heat Stress

Selenium, through incorporation into selenoproteins, is one of the key elements of the antioxidant system. Over the past few years there has been increased interest in exploring those molecular mechanisms in chicken, responsible for the development of this protection system. In more detail, Cd/Pb poisoning and heat stress increase oxidation, mRNA levels of inflammatory proteins, and apoptotic proteins. Selenium seems to enhance the antioxidant status and alleviates these effects via upregulation of antioxidant proteins and other molecular effects. In this review, we analyze avian transcriptome key elements with particular emphasis on interactions with heavy metals and on relation to heat stress.

The Influence of bFGF on the Fabrication of Microencapsulated Cartilage Cells under Different Shaking Modes

Cell encapsulation in hydrogels has been extensively used in cytotherapy, regenerative medicine, 3D cell culture, and tissue engineering. Herein, we fabricated microencapsulated cells through microcapsules loaded with C5.18 chondrocytes alginate/chitosan prepared by a high-voltage electrostatic method. Under optimized conditions, microencapsulated cells presented uniform size distribution, good sphericity, and a smooth surface with different cell densities. The particle size distribution was determined at 150–280 μm, with an average particle diameter of 220 μm. The microencapsulated cells were cultured under static, shaking, and 3D micro-gravity conditions with or without bFGF (basic fibroblast growth factor) treatment. The quantified detection (cell proliferation detection and glycosaminoglycan (GAG)/type II collagen (Col-II)) content was respectively determined by cell counting kit-8 assay (CCK-8) and dimethylmethylene blue (DMB)/Col-II secretion determination) and qualitative detection (acridine orange/ethidium bromide, hematoxylin-eosin, alcian blue, safranin-O, and immunohistochemistry staining) of these microencapsulated cells were evaluated. Results showed that microencapsulated C5.18 cells under three-dimensional microgravity conditions promoted cells to form large cell aggregates within 20 days by using bFGF, which provided the possibility for cartilage tissue constructs in vitro. It could be found from the cell viability (cell proliferation) and synthesis (content of GAG and Col-II) results that microencapsulated cells had a better cell proliferation under 3D micro-gravity conditions using bFGF than under 2D conditions (including static and shaking conditions). We anticipate that these results will be a benefit for the design and construction of cartilage regeneration in future tissue engineering applications.