Selenium deficiency induced necroptosis, Th1/Th2 imbalance, and inflammatory responses in swine ileum

Selenium deficiency modulates necroptosis-mediated intestinal inflammation in broiler through the lncRNAWSF27/miRNA1696/GPX3 axis

Deficiency of selenium (Se), an important trace element, causes diarrhea and even death in broilers, thereby affecting the economic development of poultry production. Adding Se is one way to relieve this situation; however, it has not fundamentally resolved intestinal inflammation. Therefore, we sought a new strategy to alleviate intestinal inflammation by studying the specific mechanisms of Se deficiency. By replicating the Se-deficient broiler model and establishing a chicken small intestinal epithelial cell (CSIEC) model, we determined that Se deficiency caused intestinal oxidative stress and necroptotic intestinal inflammation in broilers by decreasing glutathione peroxidase (GPX) 3 expression. Simultaneously, the expression of long non-coding RNA (lncRNA)WSF27 decreased and that of miR-1696 increased in Se-deficient intestines. Recently discovered competing endogenous RNAs (ceRNAs) form novel regulatory networks, which were found that selenoproteins are involved in ceRNA regulation. However, the mechanism of action of the non-coding RNA/GPX3 axis in Se-deficient broiler intestinal inflammation remains unclear. This study aimed to explore the mechanism through which Se deficiency regulates intestinal inflammation in broilers through the lncRNAWSF27/miR-1696/GPX3 axis. Our previous studies showed that lncRNAWSF27, miR-1696, and GPX3 have ceRNA-regulatory relationships. To further determine the role of the lncRNAWSF27/miR-1696/GPX3 axis in Se-deficient broiler intestinal inflammation, CSIEC models with GPX3 knockdown/overexpression, lncRNAWSF27 knockdown, or miR-1696 knockdown/overexpression were established to simulate intestinal injury. GPX3 knockdown, as well as lncRNAWSF27 and miR-1696 overexpression, aggravated cell damage. On the contrary, it can alleviate this situation. Our results reveal that the mechanism of lncRNAWSF27/miR-1696/GPX3 regulated Se-deficient broiler intestinal inflammation. This conclusion enriches our understanding of the mechanism of intestinal injury caused by Se deficiency and contributes to the diagnosis of Se-deficient intestinal inflammation and relevant drug development.

Probing Selenium-Deficient Chicken Spleen Th1/Th17 Differentiation Based on Selenoprotein W Targeting of PKM2/HIF1α

Selenium regulates the differentiation and function of immune cells mainly through selenoproteins. Selenoprotein W (SelW) has been shown to mitigate inflammatory bowel disease in mice by modulating the differentiation of helper T (CD4+ T) cell. Previous studies by our team have underscored SelW's critical role in safeguarding chicken spleens and splenic lymphocytes against inflammatory injury. However, research examining SelW's involvement in regulating CD4+ T cell differentiation in avian spleens remains scarce. Therefore, the selenium-deficient chicken model was constructed in this study. It was found that the spleen of selenium-deficient chickens showed significant inflammatory damage, accompanied by decreased SelW expression, diminished antioxidant capacity, heightened glycolysis, and an elevated count of Th1/Th17 cells. To elucidate the specific mechanism of SelW regulating Th1/Th17 cell differentiation, this study used molecular docking technology, fluorescence colocalization, and co-immunoprecipitation and initially confirmed the targeting relationship between SelW and pyruvate kinase M2 (PKM2). Subsequently, an in vitro model of SelW overexpression, knockdown, and TEPP-46 (PKM2 tetramer activator) cotreatment of chicken primary splenic lymphocytes was replicated. Our findings revealed that selenium deficiency triggers oxidative stress and promotes PKM2 nuclear translocation via SelW downregulation, which stabilizes HIF1α transcription in the nucleus, enhancing glycolysis and skewing chicken splenic CD4+ T cells toward the Th1/Th17 phenotype. Our study, for the first time, demonstrates the existence of an interaction between SelW and PKM2 in poultry, emphasizing SelW's paramount significance in CD4+ T cell differentiation, providing fresh perspectives on the contributions of selenoproteins to T cell biology and immune processes.

Selenium maintains intestinal epithelial cells to activate M2 macrophages against deoxynivalenol injury

Selenium (Se) is indispensable in alleviating various types of intestinal injuries. Here, we thoroughly investigated the protective effect of Se on the regulation of the epithelial cell-M2 macrophages pathway in deoxynivalenol (DON)-induced intestinal damage. In the present study, Se has positive impacts on gut health by improving gut barrier function and reducing the levels of serum DON in vivo. Furthermore, our study revealed that Se supplementation increased the abundances of GPX4, p-PI3K, and AKT, decreased the levels of 4-HNE and inhibited ferroptosis. Moreover, when mice were treated with DON and Fer-1(ferroptosis inhibitor), ferroptosis was suppressed and PI3K/AKT pathway was activated. These results indicated that GPX4-PI3K/AKT-ferroptosis was a predominant pathway in DON-induced intestinal inflammation. Interestingly, we discovered that both the number of M2 anti-inflammatory macrophages and the levels of CSF-1 decreased while the pro-inflammatory cytokine IL-6 increased in the intestine and MODE-K cells supernatant. Therefore, Se supplementation activated the CSF-1-M2 macrophages axis, resulting in a decrease in IL-6 expression and an enhancement of the intestinal anti-inflammatory capacity. This study provides novel insights into how intestinal epithelial cells regulate the CSF-1-M2 macrophage pathway, which is essential in maintaining intestinal homeostasis confer to environmental hazardous stimuli.

Nano‑selenium alleviates the pyroptosis of cardiovascular endothelial cells in chicken induced by decabromodiphenyl ether through ERS-TXNIP-NLRP3 pathway

Decabromodiphenyl ether (BDE-209) is one of the most widely used flame retardants that can infect domestic and wildlife through contaminated feed. Nano‑selenium (Nano-Se) has the advantage of enhancing the anti-oxidation of cells. Nonetheless, it remains uncertain whether Nano-Se can alleviate vascular Endothelial cells damage caused by BDE-209 exposure in chickens. Therefore, we established a model with 60 1-day-old chickens, and administered BDE-209 intragastric at a ratio of 400 mg/kg bw/d, and mixed Nano-Se intervention at a ratio of 1 mg/kg in the feed. The results showed that BDE-209 could induce histopathological and ultrastructural changes. Additionally, exposure to BDE-209 led to cardiovascular endoplasmic reticulum stress (ERS), oxidative stress and thioredoxin-interacting protein (TXNIP)-pyrin domain-containing protein 3 (NLRP3) pathway activation, ultimately resulting in pyroptosis. Using the ERS inhibitor 4-PBA in Chicken arterial endothelial cells (PAECs) can significantly reverse these changes. The addition of Nano-Se can enhance the body's antioxidant capacity, inhibit the activation of NLRP3 inflammasome, and reduce cellular pyroptosis. These results suggest that Nano-Se can alleviate the pyroptosis of cardiovascular endothelial cells induced by BDE-209 through ERS-TXNIP-NLRP3 pathway. This study provides new insights into the toxicity of BDE-209 in the cardiovascular system and the therapeutic effects of Nano-Se.

Selenium deficiency exacerbated Bisphenol A-induced intestinal toxicity in chickens: Apoptosis and cell cycle arrest mediated by ROS/P53

Bisphenol A (BPA) is a phenolic organic synthetic compound that is used as the raw material of polycarbonate plastics, and its safety issues have recently attracted wide attention. Selenium (Se) deficiency has gradually developed into a global disease affecting intestinal function via oxidative stress and apoptosis. However, the toxic effects and potential mechanisms of BPA exposure and Se deficiency in the chicken intestines have not been studied. In this study, BPA exposure and/or Se deficiency models were established in vivo and in vitro to investigate the effects of Se deficiency and BPA on chicken jejunum. The results showed that BPA exposure and/or Se deficiency increased jejunum oxidative stress and DNA damage, activated P53 pathway, led to mitochondrial dysfunction, and induced apoptosis and cell cycle arrest. Using protein-protein molecular docking, we found a strong binding ability between P53 and peroxisome proliferator-activated receptor γ coactivator-1, thereby regulating mitochondrial dysfunctional apoptosis. In addition, we used N-acetyl-L-cysteine and pifithrin-α for in vitro intervention and found that N-acetyl-L-cysteine and pifithrin-α intervention reversed the aforementioned adverse effects. This study clarified the potential mechanism by which Se deficiency exacerbates BPA induced intestinal injury in chickens through reactive oxygen species/P53, which provides a new idea for the study of environmental combined toxicity of Se deficiency, and insights into animal intestinal health from a new perspective.

Inorganic Selenium Transformation into Organic Selenium by Monascus purpureus

Selenium (Se) is a trace element that plays a crucial role in metabolism; a lack of selenium reduces the body's resistance and immunity, as well as causes other physiological problems. In this study, we aim to identify favorable conditions for improving organic selenium production. The functional microbe Monascus purpureus, which is widely used in food production, was employed to optimize selenium-enriched culture conditions, and its growth mode and selenium-enriched features were investigated. Spectrophotometry, inductively coupled plasma optical emission spectrometry (ICP-OES), and HPLC (High-Performance Liquid Chromatography) were used to determine the effects of various doses of sodium selenite on the selenium content, growth, and metabolism of M. purpureus, as well as the conversion rate of organic selenium. The best culture parameters for selenium-rich M. purpureus included 7.5 mg/100 mL of selenium content in the culture medium, a pH value of 6.8, a culture temperature of 30 °C, and a rotation speed of 180 rpm. Under ideal circumstances, the mycelia had a maximum selenium concentration of approximately 239.17 mg/kg, with organic selenium accounting for 93.45%, monacoline K production reaching 70.264 mg/L, and a secondary utilization rate of external selenium of 22.99%. This study revealed a novel biological route-selenium-rich M. purpureus fermentation-for converting inorganic selenium into organic selenium.

Micro-algal astaxanthin improves lambda-cyhalothrin-induced necroptosis and inflammatory responses via the ROS-mediated NF-κB signaling in lymphocytes of carp (Cyprinus carpio L.)

Lambda-cyhalothrin (LCY) is a widely used toxic pesticide that causes harmful effects on the immune organs of fish and aquatic species. Micro-algal astaxanthin (MAA), a heme pigment found in haematococcus pluvialis, has been shown to benefit antioxidants and immunity in aquaculture. To investigate how MAA protects carp lymphocytes from LCY-induced immunotoxicity, a model of fish lymphocytes treated with LCY and/or MAA was established. Lymphocytes from carp (Cyprinus carpio L.) were given LCY (80 μM) and/or MAA (50 μM) as a treatment for a period of 24 h. Firstly, LCY exposure resulted in excessive ROS and malondialdehyde production and reduces antioxidant enzymes (SOD and CAT), indicating a reduced capacity of the antioxidant system. Secondly, the results of flow cytometry and AO/EB labeling proved that lymphocytes treated with LCY have a larger ratio of necroptosis. In addition, LCY upregulated the levels of necroptosis-related regulatory factors (RIP1, RIP3 and MLKL) via the ROS-mediated NF-κB signaling pathway in lymphocytes. Thirdly, LCY treatment caused increased secretion of inflammatory genes (IL-6, INF-γ, IL-4, IL-1β and TNF-α), leading to immune dysfunction in lymphocytes. Surprisingly, LCY-induced immunotoxicity was inhibited by MAA treatment, indicating that it effectively attenuated the LCY-induced changes described above. Overall, we concluded that MAA treatment could ameliorate LCY-induced necroptosis and immune dysfunction by inhibiting the ROS-mediated NF-κB signaling in lymphocytes. It provides insights into the protection of farmed fish from agrobiological threats in fish under LCY and the value of MAA applications in aquaculture.

ROS mediated pyroptosis-M1 polarization crosstalk participates in inflammation of chicken liver induced by bisphenol A and selenium deficiency

The earth's natural environmental factors and man-made industrial pollution often lead to the co-occurrence of environmental pathogenic factors and malnutrition. Bisphenol A (BPA) is a serious environmental endocrine disruptor, and its exposure can cause liver tissue damage. Selenium (Se) deficiency is a worldwide problem that afflicts thousands of people, and Se deficiency can cause M1/M2 imbalance. In addition, the crosstalk between hepatocyte and immune cell is closely related to the occurrence of hepatitis. Therefore, this study found for the first time that the combined exposure of BPA and Se deficiency caused liver pyroptosis and M1 polarization through ROS, and the crosstalk between pyroptosis and M1 polarization aggravated liver inflammation in chicken. In this study, the BPA or/and Se deficiency chicken liver, single and co-culture model of LMH and HD11 cells were established. The results displayed that BPA or Se deficiency induced liver inflammation accompanied by pyroptosis and M1 polarization through oxidative stress, and increased expressions of chemokines (CCL4, CCL17, CCL19, and MIF) and inflammatory factors (IL-1β and TNF-α). The vitro experiments further verified the above changes and showed that LMH pyroptosis promoted M1 polarization of HD11 cells, and vice versa. NAC counteracted pyroptosis and M1 polarization caused by BPA and low-Se, reducing the release of inflammatory factors. In brief, BPA and Se deficiency treatment can exacerbate liver inflammation by increasing oxidative stress to induce pyroptosis and M1 polarization.

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.

Selenium deficiency increased duodenal permeability and decreased expression of antimicrobial peptides by activating ROS/NF-κB signal pathway in chickens

Selenium (Se) is an essential trace element for the body. Various organs of the body, including the intestine, are affected by its deficiency. Se deficiency can induce oxidative stress and inflammatory responses in the intestine. It can also increase intestinal permeability and decrease intestinal immune function in mammals. However, the detailed studies, conducted on the intestinal molecular mechanisms of Se deficiency-induced injury in poultry, are limited. This study explored the adverse effects of Se deficiency on intestinal permeability and its mechanism. A Se-deficient chicken model was established, and the morphological changes in the chicken duodenum tissues were observed using a light microscope and transmission electron microscope (TEM). Western blotting, qRT-PCR, and other methods were used to detect the expression levels of selenoproteins, oxidative stress indicators, inflammatory factors, tight junction (TJ) proteins, antimicrobial peptides, and other related indicators in intestinal tissues. The results showed that Se deficiency could decrease the expression levels of selenoproteins and antioxidant capacity, activate the nuclear factor kappa-B (NF-κB) pathway, cause inflammation, and decrease the expression levels of TJ proteins and antimicrobial peptides in the duodenum tissues. The study also demonstrated that Se deficiency could increase intestinal permeability and decrease antimicrobial peptides via reactive oxygen species (ROS)/NF-κB. This study provided a theoretical basis for the scientific prevention and control of Se deficiency in poultry. Se deficiency decreased the expression levels of selenoproteins and increased ROS levels to activate the NF-κB pathway, resulting in the production of pro-inflammatory cytokines, reducing the expression levels of TJ protein, and weakening the expression of antimicrobial peptides, which contributed to the higher intestinal permeability. Oxidative stress weakened the expression of antimicrobial peptides.

Subacute Cadmium Exposure Induces Necroptosis in Swine Lung via Influencing Th1/Th2 Balance

Cadmium (Cd) is a type of toxic substance, which widely exists in nature. However, the effect of Cd exposure on the toxicity of swine lungs and its underlying mechanism involved have not yet been reported. In our study, we divided swine into two groups, including a control group (C group) and Cd-exposed group. Swine in the C group were fed a basic diet, whereas swine in the Cd group were fed a 20 mg Cd/kg diet. Immunofluorescence, qRT-PCR, western blot analysis, and H&E staining were performed to detect necroptosis-related indicators. Our results found that after Cd exposure, Th1/Th2 imbalance occurred, miR-181-5p was down-regulated, TNF-α expression was increased, and the NF-κB/NLRP3 and JAK/STAT pathways and RIPK1/RIPK3/MLKL axis were activated. Furthermore, histopathological examination showed necrosis in swine lung after Cd exposure. Together, the above-mentioned results indicate that subacute Cd exposure is closely linked with necroptosis in swine lung. Our study provided evidence that Cd may act through miR-181-5p/TNF-α to induce necroptosis in swine lung. The findings of this study supplement the toxicological study of Cd and provide a reference for comparative medicine.

Intestinal barrier dysfunction induced by ammonia exposure in pigs in vivo and in vitro: The protective role of L-selenomethionine

Ammonia has been reported to have a variety of toxicity to aquatic animals, farm animals and humans. However, its potential toxicity on the intestines remains unknown. L-selenomethionine is one of the important organic selenium sources. However, the mitigating effect of L-selenomethionine on ammonia exposure toxicity is still lacking. Therefore, in this study, the mechanism of toxic action of ammonia on intestinal tract and the detoxification effect of L-selenomethionine were examined. We evaluated the intestinal toxicity of ammonia and the alleviating effect of L-selenomethionine in an in vivo model, and then verified it in vitro model by a variety of cutting-edge experimental techniques. Our results showed that ammonia exposure causes oxidative stress, necroptosis, Th1/Th2 imbalance and inflammation in the intestinal tissue and the intestinal cells, and L-selenomethionine had a significant mitigation effect on the changes of these indexes induced by ammonia. In conclusion, ammonia exposure caused oxidative stress and Th1/Th2 imbalance in the porcine small intestine and IPEC-J2 cells, and that excessive ROS accumulation-mediated necroptosis targeted inflammatory responses, resulting in the destruction of tight connections of intestinal cells, thereby causing intestinal barrier dysfunction. L-selenomethionine could effectively reduce the intestinal injury caused by ammonia exposure and antagonize the toxic effect of ammonia.

Selenium Deficiency Induces Apoptosis, Mitochondrial Dynamic Imbalance, and Inflammatory Responses in Calf Liver

Selenium (Se) deficiency significantly impacts the cow breeding industry by reducing the milk quality of dairy cows and affecting the health of calves. The molecular mechanism of Se deficiency-induced damage to calves, however, remains unclear. The present study investigated whether Se deficiency induces oxidative stress, apoptosis, and inflammation in calf liver tissues. We collected the liver tissues of calves with Se deficiency. Experimental results showed that Se deficiency weakened the activity of antioxidant enzymes and increased the accumulation of oxidation products in the liver. Se deficiency also led to excessive fission of the mitochondria and downregulated the expression of the Mfn2 and Opa1 genes in the calf liver. Mitochondrial damage-induced apoptosis by increasing the expression of pro-apoptotic genes such as CytC, Cas3, Cas9, fas, and Cas8, leading to a decrease in energy metabolism. Se deficiency also triggered the expression of inflammatory-related factors such as IL-1β, IL-6, TNF-α, and NF-κB. Taken together, the results suggest that Se deficiency causes oxidative stress, triggers an inflammatory response, disrupts mitochondrial dynamic balance, and then induces apoptosis, eventually leading to calf liver damage. These findings might provide valuable clues for elucidating the mechanism of Se deficiency-induced injury in domestic animals.

Selenium deficiency aggravates bisphenol A-induced autophagy in chicken kidney through regulation of nitric oxide and adenosine monophosphate activated protein kinase/mammalian target of rapamycin signaling pathway

Bisphenol A (BPA), a phenolic compound, is harmful to humans and animals as its residue in the water threatens multiple organs, especially the kidney. Low selenium (Se) diets are consumed in many regions of the world, and poor Se status has exacerbating effect on toxicity of several environmental chemicals. Here, we described the discovery path of Se deficiency aggravation on autophagy in BPA treated chicken kidney through regulating nitric oxide (NO) and adenosine monophosphate activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signaling pathways. The actual dietary Se intake for chickens was 0.30 mg/kg in control group and 0.03 mg/kg in Low-Se group, and BPA exposure concentration for chickens was 0.05 g/kg. Chicken embryo kidney (CEK) cells were used in vitro and the BPA exposure concentration for CEK cells was 150 nM. We found that BPA significantly increased levels of NO and inducible nitric oxide synthase, activated AMPK/mTOR signaling pathways, thereby triggering p62/LC3/Beclin1 signaling, resulting in formations of autophagosome and autolysosome, and finally stimulating autophagy in the chicken kidney. Additionally, Se deficiency promoted the occurrence of autophagy in BPA-treated kidneys. Altogether, our findings showed that Se deficiency exacerbates BPA-induced renal autophagy in chickens via regulation of NO and AMPK/mTOR signaling pathways. These findings will improve our understandings of the mechanisms of nephrotoxicity of BPA and detoxification by Se in chickens. In addition, further work is required to determine if Se status of exposed populations needs to be considered in future epidemiological assessments.

Crosstalk between regulated necrosis and micronutrition, bridged by reactive oxygen species

The discovery of regulated necrosis revitalizes the understanding of necrosis from a passive and accidental cell death to a highly coordinated and genetically regulated cell death routine. Since the emergence of RIPK1 (receptor-interacting protein kinase 1)-RIPK3-MLKL (mixed lineage kinase domain-like) axis-mediated necroptosis, various other forms of regulated necrosis, including ferroptosis and pyroptosis, have been described, which enrich the understanding of pathophysiological nature of diseases and provide novel therapeutics. Micronutrients, vitamins, and minerals, position centrally in metabolism, which are required to maintain cellular homeostasis and functions. A steady supply of micronutrients benefits health, whereas either deficiency or excessive amounts of micronutrients are considered harmful and clinically associated with certain diseases, such as cardiovascular disease and neurodegenerative disease. Recent advance reveals that micronutrients are actively involved in the signaling pathways of regulated necrosis. For example, iron-mediated oxidative stress leads to lipid peroxidation, which triggers ferroptotic cell death in cancer cells. In this review, we illustrate the crosstalk between micronutrients and regulated necrosis, and unravel the important roles of micronutrients in the process of regulated necrosis. Meanwhile, we analyze the perspective mechanism of each micronutrient in regulated necrosis, with a particular focus on reactive oxygen species (ROS).

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.

Types of necroinflammation, the effect of cell death modalities on sterile inflammation

Distinct types of immune responses are activated by infections, which cause the development of type I, II, or III inflammation, regulated by Th1, Th2, Th17 helper T cells and ILC1, ILC2 and ILC3 cells, respectively. While the classification of immune responses to different groups of pathogens is widely accepted, subtypes of the immune response elicited by sterile inflammation have not yet been detailed. Necroinflammation is associated with the release of damage-associated molecular patterns (DAMP) from dying cells. In this review, we present that the distinct molecular mechanisms activated during apoptosis, necroptosis, pyroptosis, and ferroptosis lead to the release of different patterns of DAMPs and their suppressors, SAMPs. We summarize the currently available data on how regulated cell death pathways and released DAMPs and SAMPs direct the differentiation of T helper and ILC cells. Understanding the subtypes of necroinflammation can be crucial in developing strategies for the treatment of sterile inflammatory diseases caused by cell death processes.

Selenium Deficiency Causes Inflammatory Injury in the Bursa of Fabricius of Broiler Chickens by Activating the Toll-like Receptor Signaling Pathway

The aim of our study was to observe the effect of selenium (Se) deficiency on inflammatory injury in the bursa of Fabricius of broiler chickens and to determine the role of the Toll-like receptor (TLR)/myeloid differential protein-88 (MyD88)/nuclear factor-κB (NF-κB) signaling pathway during this process. Here, we revealed that severe inflammatory injury occurred in the broiler bursa of Fabricius with Se deficiency via histopathology. Moreover, the ultrastructural pathological results showed that the nuclear, mitochondrial, endoplasmic reticulum and cytomembrane structures were damaged to varying degrees. Additionally, interleukin-2 (IL-2), interleukin-6 (IL-6), and interferon (IFN-γ) mRNA expression was markedly upregulated in the broiler bursa of Fabricius with Se deficiency. Furthermore, TLR, toll-interleukin-1 receptor domain-containing adapter-inducing interferon-β (TRIF), MyD88, and NF-κB mRNA expression was also markedly elevated in the broiler bursa of Fabricius with Se deficiency. The above results suggested that Se deficiency increases the expression of numerous proinflammatory cytokines and is probably due to the activation of the TLR/MyD88/NF-κB signaling pathway, which causes inflammatory injury in the bursa of Fabricius of broiler chickens. Our findings provide a theoretical reference for further studying the underlying mechanism of Se deficiency-induced inflammatory injury in the bursa of Fabricius of broiler chickens.

Cadmium exposure triggers oxidative stress, necroptosis, Th1/Th2 imbalance and promotes inflammation through the TNF-α/NF-κB pathway in swine small intestine

Cadmium (Cd) is a toxic environmental pollutant and induces toxic effects to organism. Nevertheless, the mechanism of Cd-induced toxicity in swine remains obscure. To explore this, 10 healthy 6-week-old weaned swine were placed into two groups stochastically, the Cd group was treated with a commercial diet containing 20 mg/kg Cd for 40 days. The results of histopathological and ultrastructural observations showed typical necrosis features and inflammatory cell infiltration in Cd group. Excessive Cd suppressed T-AOC and SOD activities, increased MDA content and ROS levels. Cd diet elevated the expression of RIPK1, RIPK3, and MLKL to activate the RIPK3-dependent necroptosis pathway. Results of Th1 and Th2 cytokines indicated that the levels of IL-4, IL-6 and IL10 was increased, while the level of IFN-γ was decreased, illustrating Th1/Th2 immune imbalance leads to aggravate inflammatory responses. Cd activated the TNF-α/NF-κB pathway and induced inflammatory responses via increasing the expression of HO-1, IL-1β, iNOS, COX2. Heat shock proteins were notably elevated in response to inflammatory reactions. And these effects were inhibited by necrostatin-1 (Nec-1) and N-acetyl-cysteine (NAC). Altogether, these data demonstrated that Cd induced necroptosis and inflammation to aggravate small intestine injury in swine by increasing the excessive accumulation of ROS and imbalanced Th1/Th2, respectively.

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.

Selenium deficiency causes apoptosis through endoplasmic reticulum stress in swine small intestine

Selenium (Se) plays a crucial role in intestinal health. However, the specific mechanism by which deficiency of Se causes intestinal damage remains unclear. This study was to explore whether Se deficiency can cause ER stress and induce apoptosis in swine small intestine. We established the Se deficiency swine model in vivo and the intestinal epithelial (IPEC-J2) cell Se deficiency model in vitro. The results of morphological observation showed that Se deficiency caused structural damage in intestinal villi and the decrease of goblet cell structure. The apoptotic characteristics such as nucleolar condensation, mitochondrial swelling, and apoptotic bodies were observed in the IPEC-J2 cells. The results of acridine orange/ethidium bromide and mitochondrial membrane potential fluorescence staining in vitro showed that there were more apoptotic cells in the Se-deficiency group than that in the control group. The protein and/or mRNA expression levels of Bax, Bcl-2, caspase 3, caspase 8, caspase 9, cytc, PERK, ATF6, IRE, XBP1, CHOP, GRP78, which are related to ER stress-apoptosis pathway, were significantly increased in the Se-deficient group which compared with the control group in vivo and in vitro were consistent. These results indicated that Se deficiency induced ER stress and increased the apoptosis in swine small intestine and IPEC-J2 cells and then caused the damage in swine small intestinal tissue. Besides, the results of gene expressions in our experiment proved that ER stress induced by Se deficiency promoted apoptosis. These results filled the blank in the mechanism of Se deficiency-induced intestinal injury in swine.

Cadmium induces endoplasmic reticulum stress-mediated apoptosis in pig pancreas via the increase of Th1 cells

Cadmium (Cd), an environmental pollutant, causes several adverse reactions in animals. High dose of Cd has serious cytotoxicities, including the induction of programmed cell necrosis, autophagy and apoptosis, which has aroused wide public concern. The balance of cytokine network is affected by Th1/Th2 balance which is closely related to immune response and the occurrence, development, treatment and outcome of various diseases. Cd can induce severe apoptosis, but the relationship between Cd induced apoptosis and Th1/Th2 balance has not been clarified. In this study, we established a pig Cd poisoning model, exposing to CdCl₂ for 40 days (20 mg Cd/kg diet). Firstly, deviation of Th1/Th2 balance was observed by fluorescence staining, and apoptosis was observed by TUNEL staining. Then, real-time fluorescence quantitative analysis and Western blot were used to detect the expression of related proteins. The results show that Cd can interfere with the balance of Th1/Th2 and shift the balance towards Th1. In addition, through the experiments, we found that Cd exposure can increase the expression of glucose-regulated protein 94 (GRP94) and glucose-regulated protein 78 (GRP78), marker proteins of unfolded protein response (UPR). Cd exposure can increase the expression of pancreatic endoplasmic reticulum kinase (PERK), CCAAT-enhancer-binding protein homologous protein (CHOP), inositol-requiring enzyme 1 (IRE-1), activating transcription factor 6 (ATF-6), cysteinyl aspartate specific proteinase (Caspase12), indicating the three branches (ATF6, PERK and IRE-1) of endoplasmic reticulum stress (ER-stress) were activated. Moreover, we found that the expression of pro-apoptosis genes in the downstream pathway of ER-stress increased. In summary, our results indicated that Cd exposure upregulated the expression of pro-apoptosis related genes and caused apoptosis via the activation of the ER-stress signaling pathways in pancreas cells. And these negative effects were correlated with the equilibrium drift of Th1/Th2, increase in the expression and secretion of Th1 cytokines.