MiR-196-5p involvement in selenium deficiency-induced immune damage via targeting of NFκBIA in the chicken trachea

miR-210/NF-κB axis: A new direction for regulating cadmium-induced pig artery inflammatory injury

Cadmium (Cd) is a toxic metal pollutant that still exists in the environment. The microRNA (miRNA) is a type of noncoding RNA that plays an important role in gene posttranscriptional regulation and disease development. Although the toxic effects of Cd have been extensively studied, studies on the mechanism of Cd from the perspective of miRNA are still limited. So, we established a Cd-exposure pig model, which confirmed that Cd exposure would cause pig artery damage. The miR-210 with the most reduced expression and the nuclear factor kappa B (NF-κB) that had a targeting relationship with miR-210 were screened. The effect of miR-210/NF-κB on the artery damage induced by Cd exposure was investigated by acridine orange/ethidium bromide staining, reactive oxygen species (ROS) staining, quantitative PCR, and western blotting. The results showed that miR-210 inhibitor, pcDNA-NF-κB could induce ROS overproduction in pig hip artery endothelial cells, thus inducing Th1/Th2 imbalance and necroptosis, leading to increased inflammation, while small interfering RNA-NF-κB played a mitigating role. In conclusion, Cd can induce artery necroptosis and Th1/Th2 imbalance by regulating the miR-210/NF-κB axis, so as to lead to artery inflammatory damage. In this study, we explored the way in which Cd exposure causes artery damage in pig, providing a new perspective on the regulatory damage of miR-210/NF-κB axis.

The role of selenoprotein M in nickel-induced pyroptosis in mice spleen tissue via oxidative stress

Nickel (Ni) is a heavy metal element and a pollutant that threatens the organism's health. Melatonin (Mel) is an antioxidant substance that can be secreted by the organism and has a protective effect against heavy metals. Selenoprotein M (SelM) is a selenoprotein widely distributed of the body, and its role is to protect these tissues from oxidative damage. To study the mechanism of Ni, Mel, and SelM in mouse spleen, 80 SelM^+/+ wild-type and 80 SelM^-/- homozygous mice were divided into 8 groups with 20 mice in each group. The Ni group was intragastric at a concentration of 10 mg/kg, while the Mel group was intragastric at 2 mg/kg. Mice were injected with 0.1 mL/10 g body weight for 21 days. Histopathological and ultrastructural observations showed the changes in Ni, such as the destruction of white and red pulp and the appearance of pyroptosomes. SelM knockout showed more severe injury, while Mel could effectively interfere with Ni-induced spleen toxicity. The results of antioxidant capacity determination showed that Ni could cause oxidative stress in the spleen, and Mel could also effectively reduce oxidative stress. Finally, Ni exposure increased the expression levels of the pyroptotic genes, including apoptosis-associated speck protein (ASC), absent in melanoma-2 (AIM2), NOD-like receptor thermal protein domain-associated protein 3 (NLRP3), Caspase-1, interleukin- (IL-) 18, and IL-1β (p < 0.05). Loss of SelM significantly increased these (p < 0.05), while Mel decreased the alleviated impact of Ni. In conclusion, the loss of SelM aggravated Ni-induced pyroptosis of the spleen via activating oxidative stress, which was alleviated by Mel, but the effect of Mel was not obvious in the absence of SelM, which reflected the important role of SelM in Ni-induced pyroptosis.

Bisphenol A exacerbates selenium deficiency-induced pyroptosis via the NF-κB/NLRP3/Caspase-1 pathway in chicken trachea

Selenium deficiency can lead to multiple tissue and organ damage in the body and could coexist with chronic toxic exposures. Contamination from Bisphenol A (BPA) exposure can induce the occurrence of various injuries including pyroptosis. However, it is not clear whether selenium deficiency and BPA exposure affect tracheal tissue pyroptosis in chickens. To investigate whether selenium deficiency and BPA exposure induce chicken tracheal tissue pyroptosis via the NF-κB/NLRP3/Caspase-1 pathway and the effect of their combined exposure on tissue injury, we developed a model of relevant chicken tracheal injury. Sixty broilers were divided into four groups: the control group (C group), selenium-deficient group (SeD group), BPA-exposed group (BPA group) and combined exposure group (SeD + BPA group). The study examined the expression indicators of markers of pyroptosis (NLRP3&GSDMD), NF-κB pathway-related inflammatory factors (NF-κB, iNOS, TNF-α, COX-2), pyroptosis-related factors (ASC, Caspase-1, IL-1β, IL-18), and some heat shock proteins and interleukins (HSP60, HSP90, IL-6, IL-17) in the samples. The results showed that the expression of the above indicators was significantly upregulated in the different treatment groups (P < 0.05). In addition, the expression levels of the above related indicators were more significantly up-regulated in the combined selenium-deficient and BPA-exposed group compared to the group in which they were individually exposed. It was concluded that selenium deficiency and BPA exposure induced tracheal tissue pyroptosis in chickens through NF-κB/NLRP3/Caspase-1 pathway, and BPA exposure exacerbated selenium deficiency-induced tracheal pyroptosis. The present study provides new ideas into studies related to the co-exposure of organismal micronutrient deficiency and chronic toxicants.

Immunosuppression participated in complement activation-mediated inflammatory injury caused by 4-octylphenol via TLR7/IκBα/NF-κB pathway in common carp (Cyprinus carpio) gills

4-octylphenol (4-OP), a toxic estrogenic environmental pollutant, can threaten aquatic animal and human health. However, toxic effect of 4-OP on fish has not been reported. To investigate molecular mechanism of gill poisoning caused by 4-OP exposure, a carp 4-OP poisoning model was established, and then blood and gills were collected on day 60. The results demonstrated that gill was a target organ attacked by 4-OP, and exposure to 4-OP caused carp gill inflammatory injury. There were 1605 differentially expressed genes (DEGs, including 898 up-regulated DEGs and 707 down-regulated DEGs). KEGG and GO were used to further analyze obtained 1605 DEGs, indicating that complement activation, immune response, and inflammatory response participated in the mechanism of 4-OP-caused carp gill inflammatory injury. Our data at transcription level further revealed that 4-OP caused complement activation through triggering complement component 3a/complement component 3a receptor (C3a/C3aR) axis and complement component 5a/complement component 5a receptor 1 (C5a/C5aR1) axis, induced immunosuppression through the imbalances of T helper (Th) 1/Th2 cells and regulatory T (Treg)/Th17 cells, as well as caused inflammatory injury via toll like receptor 7/inhibitor kappa B alpha/nuclear factor-kappa B (TLR7/IκBα/NF-κB) pathway. Taken together, immunosuppression participated in complement activation-mediated inflammatory damage in carp gills after 4-OP treatment. The findings of this study will provide pioneering information and theoretical support for the mechanism of 4-OP poisoning, and will provide reference for the assessment of estrogenic environmental pollution risk.

Selenium Deficiency Induces Autophagy in Chicken Bursa of Fabricius Through ChTLR4/MyD88/NF-κB Pathway

To explore the role of ChTLR4/MyD88/NF-κB signaling pathway on autophagy induced by selenium (Se) deficiency in the chicken bursa of Fabricius, autophagosome formation in the bursa of Fabricius was observed by transmission electron microscopy. Quantitative real-time PCR (qRT-PCR) and Western blot were used to detect the expression of ChTLR4 and its signaling pathway molecules (MyD88, TRIF, and NF-κB), inflammatory factors (IL-1β, IL-8, and TNF-α), and autophagy-related factors (ATG5, Beclin1, and LC3-II) in the Se-deficient chicken bursa of Fabricius at different ages. The results showed that ChTLR4/MyD88/NF-κB signaling pathway was activated in the chicken bursa of Fabricius and autophagy was induced at the same time by Se deficiency. In order to verify the relationship between the autophagy and ChTLR4/MyD88/NF-κB signaling pathway, HD11 cells were used to establish the normal C group, low Se group, and low Se + TLR4 inhibitor (TAK242) group. The results demonstrated that autophagy could be hindered when the TLR4 signaling pathway was inhibited under Se deficiency. Furthermore, autophagy double-labeled adenovirus was utilized to verify the integrity of autophagy flow induced by Se deficiency in HD11 cells. The results showed that it appeared to form a complete autophagy flow under the condition of Se deficiency and could be blocked by TAK242. In summary, we found that Se deficiency was involved in the chicken bursa of Fabricius autophagy occurring by activating the ChTLR4/MyD88/NF-κB pathway.

Selenium Deficiency Aggravates Heat Stress Pneumonia in Chickens by Disrupting the M1/M2 Balance

Selenium (Se) is an essential trace element found in the body. Se deficiency and M1/M2 imbalance are closely related to inflammation. Heat stress can decrease immune function and cause inflammation. In order to investigate whether Se deficiency can aggravate pneumonia caused by heat stress and the role of M1/M2 imbalance in the occurrence of pneumonia, 100 AA broilers were divided into two groups and fed the conventional diet (0.2 mg/kg Se) and the Se-deficient diet (0.03 mg/kg Se). After 40 days of feeding, the normal feeding group was randomly divided into a control group and a heat stress group. At the same time, the Se-deficient diet feeding group was randomly divided into a low Se group and a low Se heat stress group, with 25 chickens in each group. The model was established by exposure at 40℃. Six hours later, broilers were euthanized, and their lung tissues were collected. Hematoxylin and eosin staining, immunofluorescence, quantitative real-time PCR, and western blotting were used to detect lung histopathological changes and the expression of M1/M2 markers, nuclear receptor-κB (NF-κB) pathway genes, and heat shock proteins. Meanwhile, the activity and content of oxidative stress-related indices were also detected. We found that the expression of interleukin-1β, interleukin-6, interleukin-12, and tumor necrosis factor-α was upregulated and the expression of interleukin-2, interleukin-10, and interferon-γ was downregulated. Immunofluorescence showed that the expression of CD16 was increased, the expression of CD163 was weakened, and the M1/M2 imbalance was present. In addition, the NF-κB pathway was activated by the increased expressions of heat shock proteins and oxidative stress. There was an increase in malondialdehyde, nitric oxide, and inducible nitric oxide synthase content, while the activity of total antioxidant capacity, glutathione peroxidase, catalase, and superoxide dismutase decreased, and the expression of NF-κB and cyclooxygenase-2 increased. These results suggest that low Se induces M1/M2 imbalance through oxidative stress activation of the NF-κB pathway and aggravates lung tissue inflammation caused by heat stress. This study offers a theoretical basis for exploring the pathogenesis of various kinds of inflammation induced by Se deficiency from the perspective of M1/M2 and provides a reference for the prevention of such diseases.

Rutin Ameliorates Cadmium-Induced Necroptosis in the Chicken Liver via Inhibiting Oxidative Stress and MAPK/NF-κB Pathway

Cadmium (Cd) is a recognized toxic metal and exerts serious hepatotoxicity in animals and humans. Rutin (RUT) is a dietary bioflavonoid with strong antioxidant and anti-inflammatory potential. However, little is known about the alleviating effect of RUT against Cd-induced liver necroptosis. The aim of this study was to ascertain the ameliorative mechanism of RUT on necroptosis triggered by Cd in chicken liver. One hundred twenty-eight 100-day-old Isa hens were randomly divided into four groups: the control group, RUT group, Cd + RUT cotreated group, and Cd group. Cd exposure prominently elevated Cd accumulation and the activities of liver function indicators (ALT and AST). Furthermore, the histopathological results, the overexpression of genes (RIPK1, RIPK3, and MLKL) related to the necroptosis pathway, and low Caspase 8 levels in Cd-exposed chicken liver indicated that Cd intoxication induced necroptosis in chicken liver. Meanwhile, Cd administration drastically increased the levels of oxidizing stress biomarkers (ROS production, MDA content, iNOS activity, and NO generation), and obviously reduced the activities of antioxidant enzymes (SOD, GPx, and CAT) and total antioxidant capacity (T-AOC) in chicken liver. Cd treatment promoted the expression of the main members of the MAPK and NF-κB pathways (JNK, ERK, P38, NF-κB, and TNF-α) and activated heat shock proteins (HSP27, HSP40, HSP60, HSP70, and HSP90). However, RUT application remarkably alleviated these Cd-induced variations and necroptosis injury. Overall, our study demonstrated that RUT might prevent Cd-induced necroptosis in the chicken liver by inhibiting oxidative stress and MAPK/NF-κB pathway.

MiR-1656 targets GPX4 to trigger pyroptosis in broilers kidney tissues by activating NLRP3 inflammasome under Se deficiency

Selenium (Se) is a vital minor element for the organism. Se deficiency caused inflammation in kidney tissue and regulate the expression of selenoproteins and microRNAs (miRNAs). Pyroptosis involved in the inflammatory response, however, whether microRNA targets GPX4 to regulate Se-deficient kidney tissue pyroptosis is unclear. In this study, broilers were divided into two groups, Control group with 0.3mg/kg Se diet and Se-deficient group with 0.03mg/kg Se diet. The dual luciferase reporter assay system and quantitative real-time PCR (qRT-PCR) were used to screen the specificity of miR-1656 and its target protein in Se-deficient broilers. We tested the pyroptosis-related genes of Se-deficient broilers kidney and miR-1656-transfected primary broilers kidney by qRT-PCR, Western blot (WB) and immunofluorescence staining. Our research indicated that the GPX4 is one of the target genes of miR-1656, and Se deficiency leaded to the overexpression of miR-1656 and the increased expression of pyroptosis-related genes. The overexpression of miR-1656 can induce increased expression of pyroptosis-related genes including NLRP3, Caspase-1, IL-18, and IL-1β by inhibiting the release of GPX4. This study showed that miR-1656 could increase the release of ROS by targeting GPX4, activated the NLRP3 inflammasome, and release the inflammatory factors IL-1β and IL-18 to trigger pyroptosis in the kidney tissue of Se-deficient broilers. This finding may provide new research ideas for kidney injury and cell death due to Se deficiency.

Selenium-Alleviated Testicular Toxicity by Modulating Inflammation, Heat Shock Response, and Autophagy Under Oxidative Stress in Lead-Treated Chickens

Lead (Pb), a toxic pollutant, is toxic to the testis. However, biological events during testicular Pb poisoning were not well understood. Selenium (Se) has the ability to antagonize Pb toxicity. The purpose of this research was to clarify the relief mechanism of Se on testicular toxicity of Pb from the perspective of oxidative stress, inflammation, heat shock response, and autophagy in a chicken model. Sixty male Hyline chickens (7-day-old) were randomly assigned into four groups. The feeding program consisted of a commercial diet, a Se-supplemented diet (1 mg kg^-1 Se), a Pb-supplemented diet (350 mg L^-1 Pb), and a Se- and Pb-supplemented diet, respectively. On the 12th week, serums were collected to measure testosterone level and testes were removed to determine testis weight, histological structure, Pb and Se concentrations, oxidative stress indicators, and mRNA and protein expression of inflammatory cytokines, heat shock proteins, and autophagy-related genes. The results showed that Pb poisoning changed the histological structure of testes; decreased serum testosterone level, testis weight, catalase, glutathione-s-transferase, and total antioxidative capacity activities; increased hydrogen peroxide content; inhibited interleukin (IL)-2 and mammalian target of rapamycin expression; and promoted IL-4, IL-12β, heat shock proteins, Beclin 1, Dynein, autophagy-related proteins 5, light chain 3 (LC3)-I, and LC3-II expression in the testes of chickens. Se intervention mitigated the aforementioned alterations induced by Pb. In conclusion, Pb led to oxidative stress, which triggered inflammation, heat shock response, and autophagy. Se administration mitigated testicular toxicity of Pb mainly by mitigating oxidative stress in male chickens.

MicroRNA-294 Regulates Apoptosis of the Porcine Cerebellum Caused by Selenium Deficiency via Targeting iNOS

Deficiency of the essential trace element selenium (Se) can lead to cell apoptosis, and various microRNAs (miRNAs) are known to participate in the regulation of apoptosis by regulating their target genes. In this study, we explore the effect of Se deficiency on porcine cerebellar cell apoptosis and the role of miRNA in this process. After constructing a low-Se pig model, we observed the porcine cerebellum through an electron microscope and observed obvious characteristics of apoptosis. Moreover, it was found that the expression of miR-294 in Se-deficient pigs was significantly lower than that in the control group. Through bioinformatics, qRT-PCR, western blot analysis, and other experimental techniques, we further confirmed that inducible nitric oxide synthase (iNOS) is one of the target genes of miR-294. Our experimental results show that Se deficiency can reduce the expression of miR-294 and increase both the expression of iNOS and the nitric oxide (NO) content (P < 0.01). The expression of heat shock proteins (HSPs, such as HSP70, HSP90, HSP60, HSP40, and HSP27) and mitochondrial pathway-related indicators, such as Bcl2-associated X protein (Bax), cytochrome C (Cyt-C), and cysteinyl aspartate-specific proteinases (caspase 3, caspase 7, and caspase 8), was upregulated (P < 0.05), and the expression of B cell lymphoma-2 (Bcl-2) was downregulated (P < 0.05). In summary, we believe that Se deficiency can lead to abnormal expression of miR-294 and HSPs; moreover, the mitochondrial apoptosis pathway is activated, which significantly enhances apoptosis of cerebellar cells in Se-deficient pigs. These results enrich the biological effects of Se deficiency.

Macrophage-biomimetic porous Se@SiO2 nanocomposites for dual modal immunotherapy against inflammatory osteolysis

Background

Inflammatory osteolysis, a major complication of total joint replacement surgery, can cause prosthesis failure and necessitate revision surgery. Macrophages are key effector immune cells in inflammatory responses, but excessive M1-polarization of dysfunctional macrophages leads to the secretion of proinflammatory cytokines and severe loss of bone tissue. Here, we report the development of macrophage-biomimetic porous SiO₂-coated ultrasmall Se particles (porous Se@SiO₂ nanospheres) to manage inflammatory osteolysis.

Results

Macrophage membrane-coated porous Se@SiO₂ nanospheres(M-Se@SiO₂) attenuated lipopolysaccharide (LPS)-induced inflammatory osteolysis via a dual-immunomodulatory effect. As macrophage membrane decoys, these nanoparticles reduced endotoxin levels and neutralized proinflammatory cytokines. Moreover, the release of Se could induce macrophage polarization toward the anti-inflammatory M2-phenotype. These effects were mediated via the inhibition of p65, p38, and extracellular signal-regulated kinase (ERK) signaling. Additionally, the immune environment created by M-Se@SiO₂ reduced the inhibition of osteogenic differentiation caused by proinflammation cytokines, as confirmed through in vitro and in vivo experiments.

Conclusion

Our findings suggest that M-Se@SiO₂ have an immunomodulatory role in LPS-induced inflammation and bone remodeling, which demonstrates that M-Se@SiO₂ are a promising engineered nanoplatform for the treatment of osteolysis occurring after arthroplasty.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01128-4.

Calcium overload and reactive oxygen species accumulation induced by selenium deficiency promote autophagy in swine small intestine

Selenium (Se) deficiency can seriously affect the small intestine of swine, and cause diarrhea in swine. However, the specific mechanism of Se deficiency-induced swine diarrhea has rarely been reported. Here, to explore the damage of Se deficiency on the calcium homeostasis and autophagy mechanism of swine, in vivo and in vitro models of swine intestinal Se deficiency were established. Twenty-four pure line castrated male Yorkshire pigs (45 d old, 12.50 ± 1.32 kg, 12 full-sibling pairs) were divided into 2 equal groups and fed Se-deficient diet (0.007 mg Se/kg) as the Se-deficiency group, or fed Se-adequate diet (0.3 mg Se/kg) as the control group for 16 weeks. The intestinal porcine enterocyte cell line (IPEC-J2) was divided into 2 groups, and cultured by Se-deficient medium as the Se-deficient group, or cultured by normal medium as the control group. Morphological observations showed that compared with the control group, intestinal cells in the Se-deficiency group were significantly damaged, and autophagosomes increased. Autophagy staining and cytoplasmic calcium staining results showed that in the Se-deficiency group, autophagy increased and calcium homeostasis was destroyed. According to the reactive oxygen species (ROS) staining results, the percentage of ROS in the Se-deficiency group was higher than that in the control group in the in vitro model. Compared with the control group, the protein and mRNA expressions of autophagy-calcium-related genes including Beclin 1, microtubule-associated proteins 1A (LC3-1), microtubule-associated proteins 1B (LC3-2), autophagy-related protein 5 (ATG5), autophagy-related protein 12 (ATG12), autophagy-related protein 16 (ATG16), mammalian target of rapamycin (mTOR), calmodulin-dependent protein kinase kinase β (CAMKK-β), adenosine 5′-monophosphate-activated protein kinase (AMPK), sarco(endo)plasmic reticulum Ca²⁺-ATPase (SERCA), and calpain in the Se-deficiency group were significantly increased which was consistent in vivo and in vitro (P < 0.05). Altogether, our results indicated that Se deficiency could destroy the calcium homeostasis of the swine small intestine to trigger cell autophagy and oxidative stress, which was helpful to explain the mechanism of Se deficiency-induced diarrhea in swine.

Immunomodulatory effects of selenium-enriched peptides from soybean in cyclophosphamide-induced immunosuppressed mice

In this study, selenium-enriched soybean peptides (<3 kDa, named Se-SPep) was isolated and purified from the selenium-enriched soybean protein (Se-SPro) hydrolysate by ultrafiltration. The in-vivo immunomodulatory effects of Se-SPep were investigated in cyclophosphamide-induced immunosuppressed mice. Se-SPep treatment could alleviate the atrophy of immune organs and weight loss observed in immunosuppressive mice. Besides, Se-SPep administration could dramatically improve total protein, albumin, white blood cell, immunoglobulin (Ig) M, IgG, and IgA levels in blood. Moreover, Se-SPep strongly stimulated interleukin-2 (IL-2), interferon-gamma (IFN-γ), nitric oxide (NO), and cyclic guanosine monophosphate productions by up-regulating mRNA expressions of IL-2, IFN-γ, and inducible NO synthase in spleen tissue. Furthermore, Se-SPep exhibits more effective immunomodulatory activity compared to Se-SPro and SPep. In conclusion, Se-SPep could effectively enhance the immune capacity of immunosuppressive mice. These findings confirm Se-SPep is an effective immunomodulator with potential application in functional foods or dietary supplements.

Selenium-deficient diet induces inflammatory response in the pig adrenal glands by activating TLR4/NF-κB pathway via miR-30d-R_1

Selenium (Se) is an important trace element to maintain the body's dynamic balance. Lack of Se can cause inflammation. Studies have shown that inflammation often leads to disorders of the hypothalamic-pituitary-adrenal axis, but the mechanism by which Se deficiency causes inflammation of the porcine adrenal glands is still unclear. In order to study the effect of Se deficiency on the adrenal glands of pigs, we obtained Se-deficient pig adrenal glands through a low-Se diet. The results of mass spectrometry showed that the Se content in the Se-deficient group was only one-tenth of the control group. We detected the expression of the toll-like receptor 4 (TLR4) and downstream factors by qRT-PCR and Western blotting, and found that the lack of Se affected the TLR4/NF-κB pathway. It is known that miR-155-3p, miR-30d-R_1, and miR-146b have all been verified for targeting relationship with TLR4. We confirmed by qRT-PCR that miR-30d-R_1 decreased most significantly in the Se-deficient pig model. Then we tested 25 selenoproteins and some indicators of oxidative stress. It is confirmed that Se deficiency reduces the antioxidant capacity and induces oxidative stress in pig adrenal tissue. In short, a diet lacking Se induces oxidative stress in pig adrenal tissues and leads to inflammation through the miR-30d-R_1/TLR4 pathway. This study provides a reference for the prevention of adrenal inflammation in pigs from a nutritional point of view.

Dietary Selenium Regulates microRNAs in Metabolic Disease: Recent Progress

Selenium (Se) is an essential element for the maintenance of a healthy physiological state. However, due to environmental and dietary factors and the narrow safety range of Se, diseases caused by Se deficiency or excess have gained considerable traction in recent years. In particular, links have been identified between low Se status, cognitive decline, immune disorders, and increased mortality, whereas excess Se increases metabolic risk. Considerable evidence has suggested microRNAs (miRNAs) regulate interactions between the environment (including the diet) and genes, and play important roles in several diseases, including cancer. MiRNAs target messenger RNAs to induce changes in proteins including selenoprotein expression, ultimately generating disease. While a plethora of data exists on the epigenetic regulation of other dietary factors, nutrient Se epigenetics and especially miRNA regulated mechanisms remain unclear. Thus, this review mainly focuses on Se metabolism, pathogenic mechanisms, and miRNAs as key regulatory factors in Se-related diseases. Finally, we attempt to clarify the regulatory mechanisms underpinning Se, miRNAs, selenoproteins, and Se-related diseases.

The Alleviative Effects of Quercetin on Cadmium-Induced Necroptosis via Inhibition ROS/iNOS/NF-κB Pathway in the Chicken Brain

Cadmium (Cd), a ubiquitous environmental pollutant, has neurotoxicity to humans and animals. Quercetin (QE), the main component of flavonoids, has strong antioxidant and anti-inflammatory effects. However, little is reported about the influence of Cd exposure on necroptosis in the chicken brain and the antagonistic impacts of QE against Cd-induced brain necroptosis. The aim of this study was to ascertain the alleviative mechanism of QE on Cd-induced necroptosis in the chicken brain. Two hundred 3.5-month-old Isa hens were randomly divided into four groups, control group, QE group, Cd group, and Cd + QE co-administration group. The histopathological analysis indicated that necrosis features were observed in the Cd-intoxicated chicken brains. Meanwhile, the expression levels of RIPK1, RIPK3, and MLKL were elevated and the level of Caspase 8 was reduced in the Cd group, which further testified Cd triggered the occurrence of necroptosis in the chicken brain. Cd exposure obviously increased Cd accumulation, ROS generation, and MDA level; weakened the activities of antioxidase (SOD, GPx, and CAT); enhanced iNOS activity and NO production; promoted the expression of inflammatory factors (NF-κB, TNFα, COX-2, iNOS, PTGEs, and IL-1β); and activated HSPs (HSP27, HSP40, HSP60, HSP70, and HSP90). But, these Cd-caused variations were obviously attenuated in the Cd + QE group. This study indicated that QE had an alleviative effect on Cd-induced necroptosis in the chicken brain through inhibition ROS/iNOS/NF-κB pathway.

Research progress on separation of selenoproteins/Se-enriched peptides and their physiological activities

Selenium (Se) is an essential nutrient associated with several physiological processes in humans and has raised interest because of its antioxidant and immune properties. Se deficiency is related to a variety of diseases and dysfunctions in humans. Due to its higher bioavailability and lower toxicity, organic Se is more recommendable than inorganic Se in the frame of a balanced diet. Se is present in 25 identified selenoproteins that commonly occur in human organisms. As part of selenocysteine (SeC), Se becomes co-translationally incorporated into the polypeptide chain and involved in the regulation of oxidative stress, redox mechanisms, and other crucial cellular processes responsible for innate and adaptive immune responses. This review presents the current information regarding the presence of selenoproteins in the human body, and the separation of selenoproteins and selenopeptides from various plants and their physiological roles in the immune and oxidation systems of humans. In general, the application of selenoproteins and Se-enriched peptides are practically important for the clinical arena, whereby it can be used for exploring new healthy foods.

NLRP3 inflammasome mediated pyroptosis is involved in cadmium exposure-induced neuroinflammation through the IL-1β/IkB-α-NF-κB-NLRP3 feedback loop in swine

Cadmium (Cd) chloride, as widely distributed toxic environmental pollutants by using in industry, severely imperils animal and human health. Pyroptosis is a Cas1-dependent pro-inflammatory programmed cell death and involves in various types of diseases. Nevertheless, the mechanism of pyroptosis and Cd-induced neurotoxicity remains obscure. To investigate the specific molecular mechanisms of Cd-induced neurotoxicity, 10 weaned piglets were randomly divided into 2 groups treated with 0 and 20 mg/kg CdCl₂ in the diet for 40 days. The levels of pyroptosis, mitochondrial and inflammation-related genes were validated by qRT-PCR and WB in vivo. Our results revealed that Cd caused cerebral histopathology lesions, inducing cerebral pyroptosis and the mass generation of inflammatory cytokines, as indicated by the increased NLRP3 inflammasome activation (NLRP3, Cas1 and ASC) and the upregulation of inflammation factors IL-2, IL-6, IL-7 and inhibition of IL-10. Subsequently, further research indicated that Cd triggered pyroptosis via activating the TRAF6-IkB-α-NF-κB pathway, which interfered with the phosphorylation and ubiquitination of IkB-α. Furthermore, Cd caused mitochondrial dysfunction and fragmentation by inhibiting the AMPK-PGC-1α-NRF1/2 signaling pathway and reduced the expression of mitochondrial-related regulatory factors OPA1, TFAM and mtDNA, resulting in the increase of NLRP3 inflammasome. Besides, we found eight hub genes (IKK, IKB-α, NLRP3, TRAF6, NF-κB, AMPK, TNFα and PGC-1α), mainly related to the interaction between the NF-κB pathway and NLRP3 inflammasome. Overall, these results demonstrated that Cd could promote the IL-1β/IkB-α-NF-κB-NLRP3 inflammasome activation positive feedback loop to result in neuroinflammation in swine, which provided new insights in understanding Cd-induced toxicity.

Antagonistic effect of VDR/CREB1 pathway on cadmium-induced apoptosis in porcine spleen

Cadmium (Cd) is a toxic trace element that can enter the environment with industrial waste and accumulate in the body but the health effects of Cd on ternary pigs are still lacking in research. In order to explore the effect of Cd on the apoptosis of pig spleen and its mechanism, this study chose ternary pig as the research object to detect relevant indicators in pig spleen under Cd exposure. The results of this study showed that Cd exposure can induce apoptosis by promoting the absorption of various toxic trace elements in the spleen and inducing oxidative stress. We also found that the mechanism of Cd-induced apoptosis is closely related to the VDR/CREB1 pathway. On the one hand, Cd exposure can activate VDR, and indirectly regulate the CYP family, affecting the normal function of the spleen. On the other hand, VDR and its downstream genes antagonize the toxicity of Cd by maintaining the stability of the mitochondrial-related endoplasmic reticulum membrane structure. Our research will help researchers to further understand the physiological toxicity of Cd.

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

OBJECTIVE

This study was aimed to explore the possible mechanism of environmental metal cadmium (Cd) inducing apoptosis of pig lymph nodes.

METHOD

10 healthy 6-week-old weaned piglets were randomly divided into two groups (n = 5 pigs/group). The control group was fed with a basic diet, and the test group was fed with a basic diet of 20 mg/kg CdCl₂.

RESULTS

The Cd deposition in mesenteric lymph nodes (MLN), inguinal lymph nodes (ILN) and submaxillary lymph nodes (SLN) after Cd exposure was 2.37 folds, 1.4 folds and 1.8 folds of the control group, respectively. And the rate of MLN and ILN apoptotic cells in the Cd group was 4.11 folds and 9.18 folds of the control group, respectively. The mRNA levels of SOD1, SOD2, CAT, GPX1 and GSH in the Cd group were reduced. Similarly, the two-phase detoxification enzymes had a significant downward trend. Cd exposure decreased the activities of GSH, GSH-Px, SOD, CAT, and increased H₂O₂ and MDA levels. The mRNA and protein levels of Drp1 and Mff in the Cd group were higher than the corresponding control group, and the mRNA and protein levels of Mfn1 and Mfn2 were lower than those in the control group. In addition, the mRNA and protein levels of pro-apoptotic genes in the Cd group were lower than those in the control group. Cd can significantly reduce the expression of PI3K, AKT and HIF-1α in the three lymph nodes. In summary, Cd induces oxidative stress and regulates the PI3K/AKT/HIF-1α signal transduction pathway to cause mitochondrial dynamics disorder, which leads to the apoptosis of pig lymph nodes, suggesting that Cd-induced mitochondrial pathway apoptosis is related to Cd pig lymph nodes play an important role in the toxicity mechanism.