The co-expression of circRNA and mRNA in the thymuses of chickens exposed to ammonia

Identification and functional analysis of circular RNA expression profiles associated with ammonia exposure in chicken lungs

Ammonia acts as a detrimental atmospheric pollutant, posing a sever threat to respiratory tract health and causing lung injury in humans and animals. Circular RNAs (circRNAs) are a distinctive class of non-coding RNA generated by back-splicing of linear RNA, implicated in various biological processes. However, their role in the immune response of chicken lungs to ammonia exposure remains unclear. In this study, we examined the expression profiles of circRNAs in chicken lungs under ammonia stimulation. In total, 61 differentially expressed (DE) circRNAs were identified between the ammonia exposure and control groups, including 17 up-regulated and 44 down-regulated circRNAs. The source genes of these DE circRNAs were predominantly enriched in Influenza A, SNARE interactions in vesicular transport, and Notch signaling pathway. Notably, nine DE circRNAs (circNBAS, circMTIF2, circXPO1, circSNX24, circRAB11A, circARID3B, circUSP54, circPPARA, and circERG) were selected for validation the reliability and authenticity of RNA-seq data. Results showed the back-splicing circular structure, as well as the reliability and accuracy of RNA-seq data in quantifying circRNA expression, as the RT-qPCR results were in agreement with the RNA-seq data. Moreover, we constructed the circRNA-miRNA-mRNA regulatory networks and identified several regulatory networks in chicken lungs under ammonia stimulation, including circRAB11A-gga-miR-191b-3p-BRD2 and circARID3B-gga-miR-1696-CKS2. Taken together, our study delineates the circRNA expression profile and their potential roles in the immune response of chicken lungs to ammonia exposure. These findings offer insights into molecular mechanisms that may mitigate diseases associated with ammonia induced respiratory tract pollution in humans and animals.

Genomic analysis and functional properties of Lactobacillus johnsonii GJ231 isolated from healthy beagles

Probiotics are one of the management tools to improve the host's healthy microbiota. The positive effects of probiotics on host health are species-specific, so probiotics isolated from host's own gut may be most beneficial. Many of the metabolites (e.g., short-chain fatty acids, bacteriocins, and hydrogen peroxide) produced by Lactobacillus johnsonii have specific inhibitory profiles against invading pathogens. In this study, we isolated L. johnsonii GJ231 from the intestinal tract of healthy female beagles. The genome size of 1.763 M encoded a total of 1,691 predicted genes. Many carbohydrate-active enzymes responsible for carbohydrate degradation and the production of short-chain fatty acids were also predicted. The metabolic profile of short-chain fatty acids in L. johnsonii GJ231 was determined using LC-MS/MS. The bacteriocin-producing gene bacteriocin (lactacin F) in L. johnsonii GJ231 was also predicted. In vitro, experiments demonstrated that GJ231 can thrive in weak acids, 0.3% bile salts, and artificial gastrointestinal fluid models. It was tolerant of to high temperatures up to 70°C, was non- hemolytic, inhibited pathogenic bacteria, and had a high antioxidant capacity. In vivo safety experiments conducted in mice revealed that oral administration of GJ231 not only had no toxic side effect but also increased their antioxidant capacity. In conclusion, combining the above test results, which collectively demonstrate that canine-derived L. johnsonii GJ231 was a non-pathogenic, acid-tolerant and bile-salt-tolerant probiotic strain that inhibits pathogenic bacteria and improves host antioxidant function. This may make it a promising candidate for the development of innovative functional foods for pets.

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 antagonism mechanism of astilbin against cadmium-induced injury in chicken lungs via Treg/Th1 balance signaling pathway

The purpose of this study was to investigate the effect of Treg/Th1 imbalance in cadmium-induced lung injury and the potential protective effect of astilbin against cadmium-induced lung injury in chicken. Cadmium exposure significantly decreased T-AOC and GSH-Px levels and SOD activity in the chicken lung tissues. In contrast, it significantly increased the MDA and NO levels. These results indicate that cadmium triggers oxidative stress in lungs. Histopathological analysis revealed that cadmium exposure further induced infiltration of lymphocytes in the chicken lungs, indicating that cadmium causes pulmonary damage. Further analysis revealed that cadmium decreased the expression of IL-4 and IL-10 but increased those of IL-17, Foxp3, TNF-α, and TGF-β, indicating that the exposure of cadmium induced the imbalance of Treg/Th1. Moreover, cadmium adversely affected chicken lung function by activating the NF-kB pathway and inducing expression of genes downstream to these pathways (COX-2, iNOS), associated with inflammatory injury in the lung tissue. Astilbin reduced cadmium-induced oxidative stress and inflammation in the lungs by increasing antioxidant enzyme activities and restoring Treg/Th1 balance. In conclusion, our results suggest that astilbin treatment alleviated the effects of cadmium-mediated lung injury in chickens by restoring the Treg/Th1 balance.

Luteolin enhanced antioxidant capability and induced pyroptosis through NF-κB/NLRP3/Caspase-1 in splenic lymphocytes exposure to ammonia

During feeding process in intensive chicken farms, the prolonged exposure of chickens to elevated level of ammonia leads to substantial economic losses within poultry farming industry. Luteolin (Lut), known as its anti-inflammatory and antioxidant properties, possesses the ability to eliminate free radicals and enhance the activities of antioxidant enzymes, thus rendering it highly esteemed in production. The objective of this study was to examine the effects of Lut on antioxidant and anti-inflammatory responses of chicken splenic lymphocytes exposed to ammonia. In order to achieve this, we have replicated a protective model involving Lut against ammonia exposure in chicken splenic lymphocytes. The findings of the study indicated that Lut mitigated the elevation of lactate dehydrogenase (LDH), malondialdehyde (MDA), and reactive oxygen species (ROS) induced by ammonia poisoning. Additionally, Lut demonstrated an increase in the expression of antioxidant enzymes, namely superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Furthermore, Lut exhibited a protective effect on cell morphology and ultrastructure following exposure to ammonia. Moreover, Lut exhibited a reduction in the expression of heat shock proteins (HSPs) and inflammatory cytokines, which were found to be highly expressed in splenic lymphocytes after ammonia exposure. Additionally, Lut demonstrated the ability to inhibit the overexpression of pyroptosis-related genes and proteins (NLRP3 and Caspase-1) in splenic lymphocytes following ammonia exposure. Lut exerted an antioxidant effect on lymphocytes, counteracting elevated levels of oxidative stress following exposure to ammonia. Additionally, Lut had the potential to modulate the expression of HSPs, suppressed the inflammatory response subsequent to ammonia exposure, and influenced the expression of NLRP3 and Caspase-1, thereby mitigating pyroptosis induced by ammonia exposure. The exploration of this subject matter can elucidate the protective properties of Lut against NH4Cl-induced damage in chicken splenic lymphocytes, while also offer insights and experimental groundwork for the utilization of natural therapeutics in animal husbandry to prevent and treat ammonia-related conditions.

CircMYO1B/miR-155 pathway is a common mechanism of stress-induced immunosuppression affecting immune response to three vaccines in chicken

Stress-induced immunosuppression (SIIS) can weaken the immune response effect of poultry vaccination, and bring huge hidden dangers and economic losses to the poultry industry. However, the detailed molecular mechanisms are still not fully understood. Unveiling the common mechanism of SIIS affecting the immune response to different vaccines is critical for detecting and minimizing the losses caused by SIIS. This study used glucocorticoid dexamethasone (Dex) to simulate SIIS, and three classic avian vaccines (including avian influenza virus (AIV), Newcastle disease virus (NDV), and infectious bursal disease virus (IBDV)) were used to induce immune responses in chicken. Quantitative real-time PCR (qRT-PCR) revealed the expression characteristics and functions of circMYO1B and miR-155 in the processes of SIIS affecting the immune response to the aforementioned avian vaccines, as well as their targeted regulatory relationship. Subsequent bioinformatics analysis predicted FOS, one of the potential target genes of miR-155. The results showed that circMYO1B/miR-155 pathway served as a key common mechanism by which SIIS affected the immune response to the three vaccines. Both heart and proventriculus appeared to be the crucial tissues for this process, with five days post immunization (dpi) emerging as the primary time of interest. Moreover, mitogen-activated protein kinase (MAPK) signaling system played a key role in modulating the immune response subsequent to SIIS administration. Our findings provide new insights into the immune function of competitive endogenous RNA (ceRNA), which have important function in the detection and treatment of SIIS affecting vaccine immunity.

Modulation of the immune system of chickens a key factor in maintaining poultry production-a review

The awareness of poultry production safety is constantly increasing. The safety of poultry production is defined as biosecurity and the health status of birds. Hence the constant pursuit of developing new strategies in this area is necessary. Biosecurity is an element of good production practices that ensures adequate hygiene and maintaining the health status of poultry production. Poultry production is the world leader among all livestock species. Producers face many challenges during rearing, which depend on the utility type, the direction of use, and consumer requirements. For many years, the aim was to increase production results. Increasing attention is paid to the quality of the raw material and its safety. Therefore, it is crucial to ensure hygiene status during production. It can affect the immune system's functioning and birds' health status. Feed, water, and environmental conditions, including light, gases, dust, and temperature, play an essential role in poultry production. This review aims to look for stimulators and modulators of the poultry immune system while affecting the biosecurity of poultry production. Such challenges in current research by scientists aim to respond to the challenges posed as part of the One Health concept. The reviewed issues are a massive potential for an innovative approach to poultry production and related risks as part of the interaction of the animal-human ecosystem.

Circular RNA circAKIRIN2 participates in the process of stress-induced immunosuppression affecting immune response to infectious bursal disease virus vaccine in chicken

At present, stress-induced immunosuppression is still a hidden threat that leads to immunization failure and outbreaks of poultry diseases, and causes huge economic losses to the modern poultry industry. However, the molecular mechanisms of stress-induced immunosuppression affecting viral vaccine immunity are still poorly understood. Here, we identified circAKIRIN2 as a conserved circular transcript in chicken, and explored its expression patterns in different immune states by quantitative real-time PCR (qRT-PCR), then conducted bioinformatics analysis. The results showed that circAKIRIN2 actively participated in the process of stress-induced immunosuppression affecting the immune response to infectious bursal disease virus (IBDV) vaccine. The key time points for circAKIRIN2 involving in the process were 2 day post immunization (dpi), 5 dpi, and 28 dpi, especially at the acquired immune stage. The important tissues that responded to the process included the heart, liver, and lung, all of which changed significantly. In addition, circAKIRIN2 as a competing endogenous RNA (ceRNA) sponging zinc finger and BTB domain containing 20 (ZBTB20) was a potential molecular mechanism for regulating immune functions in the process. In conclusion, circAKIRIN2 is a key regulatory factor for stress-induced immunosuppression affecting the IBDV vaccine immune response, and this study can provide a new perspective for exploring the molecular regulatory mechanisms of stress-induced immunosuppression affecting immune response.

Characterization of circular RNA expression profiles in the age-related thymic involution of Magang goose

The thymus is a vital immune organ, but its function gradually declines with age. Circular RNAs (circRNAs) are related to the development of tissues and organs. In this study, bioinformatics analysis showed that 1329, 755, and 417 circRNAs were differentially expressed between the comparison groups of 6-month age (M6) and 20-embryo age (E20), 3-day post-hatch (P3), and 3-month age (M3) Magang geese, respectively. Among them, 167 circRNAs were differentially co-expressed between thymic development (E20, P3, and M3) and involution (M6). Functional analysis showed significant enrichment of phosphorylation and positive regulation of GTPase activity. Furthermore, pathway analysis has shown that glycerolipid metabolism and the Wnt signaling pathway are critical pathways in the thymic involution process. Finally, we constructed the competitive endogenous RNA (ceRNA) network. The results of this study suggest that circRNAs may be involved in the age-related thymic involution of the Magang goose.

Ammonia-induced excess ROS causes impairment and apoptosis in porcine IPEC-J2 intestinal epithelial cells

Ammonia is one of the most important toxic metabolites in the intestine of animals. It can cause intestinal damage and associated intestinal diseases through different endogenous or exogenous stimuli. However, the definition of harmful ammonia concentration and the molecular mechanism of ammonia - induced intestinal epithelial injury remain unclear. In this study, we found that the viability of porcine IPEC-J2 intestinal epithelial cells significantly decreased with the increase of NH₄Cl dose (20-80 mM). Ammonia (40 mM NH₄Cl) increased the expression level of ammonia transporter RHCG and disrupted the intestinal barrier function of IPEC-J2 cells by reducing the expression levels of the tight junction molecules ZO-1 and Claudin-1. Ammonia caused elevated levels of ROS and apoptosis in IPEC-J2 cells. This was manifested by decreased activity of antioxidant enzymes SOD and GPx, decreased mitochondrial membrane potential, and increased cytoplasmic Ca²⁺ concentration. In addition, the expression levels of apoptosis-related molecules Caspase-9, Caspase-3, Fas, Caspase-8, p53 and Bax were increased, the expression level of anti-apoptotic molecule Bcl-2 was decreased. Moreover, the antioxidant NAC (N-acetyl-L-cysteamine) effectively alleviated ammonia-induced cytotoxicity, reduced ROS level, Ca²⁺ concentration, and the apoptosis of IPEC-J2 cells. The results suggest that ammonia-induced excess ROS triggered apoptosis through mitochondrial pathway, death receptor pathway and DNA damage. This study can provide reference and theoretical basis for the definition of harmful ammonia concentration in pig intestine and the effect and mechanism of ammonia on pig intestinal health.

Differential expression and functional analysis of circRNA in the ovaries of Yili geese at different egg-laying stages

BACKGROUND

Ovarian development is regulated by genes that are expressed dynamically and stage-specifically. Circular RNA (circRNA) has been proven to play a significant role in the regulation of animal reproduction.

OBJECTIVE

Studying the expression characteristics of circRNAs in goose ovaries at various egg-laying stages can provide a reference for the molecular regulation mechanism of ovary development in geese that is mediated by circRNAs.

METHODS

In this study, the expression profiles of circRNAs were compared in ovary tissues from Yili geese in three different breeding periods, namely the prelaying period (KL), laying period (CL), and ceased period (XL), and differentially expressed circRNAs related to ovarian development in Yili geese were screened. The potential biological functions of differential circRNAs were predicted by bioinformatics, and the differential circRNA-miRNA regulatory network was constructed.

RESULTS

The results showed that a total of 4483 circRNAs were identified in 12 ovarian tissue samples from Yili geese at different laying stages. In the KL vs. CL, XL vs. CL, and XL vs. KL groups, 159, 455, and 383 differentially expressed circRNAs were identified, respectively. The host genes of the differential circRNAs were mostly enriched in the signal transduction, metabolism, and other related pathways, such as those for phototransduction, glycerophospholipid metabolism, aminoacyl-tRNA biosynthesis, and retinol metabolism. Finally, we constructed circRNA-miRNA regulation networks. Nine differential circRNAs were randomly selected for qRT-PCR verification, and the expression trends were consistent with the sequencing results.

CONCLUSIONS

Our results indicated that significant differences in the expression profiles of circRNAs in the ovaries of Yili geese at different egg-laying stages. Meanwhile, through analyzing the differential circRNA-miRNA interaction network, core regulators such as circRNA NW_013186107.1:36835|52,574 and gga-miR-34b-5p were screened. This study provides a reference for the further analysis of the molecular regulatory mechanism of the circRNAs regulating goose ovary development and enriches the theory of genetic regulation during goose ovary development.

Liver transcriptome analysis reveals biological pathways and transcription factors in response to high ammonia exposure

Aim: Ammonia is a toxic gas that not only causes environmental pollution, but also is harmful to human health after inhalation. Liver is an important detoxification organ that can convert external or metabolized toxic substances into nontoxic substances. However, the toxic effects of ammonia exposure on livers have not been well studied.Method: In this study, pigs were used as an animal model and were exposed to 80 ppm ammonia (8 h during 12 days), and then, RNA-seq were conducted to explore the key genes in response to high ammonia exposure in livers.Result: Gene set enrichment analysis (GSEA) showed that the genes associated with hypoxia, inflammatory response, and apoptosis were up-regulated in the ammonia group, but the genes associated with DNA replication, linoleic acid metabolism, and glycolysis were down-regulated. Totally, 556 differentially expressed genes (DEGs) including 54 genes that encode the transcription factors (TFs) were identified between the exposure and control groups. GO and KEGG pathway analysis suggested that these DEGs were involved in inflammatory response, oxidative stress, apoptosis, immune, and cell cycle. Furthermore, the TF-target interaction analysis showed that FOS, HIF-1α, JUNB, ATF3, REL, and KLF4 were important TFs in regulating the hepatic gene expression in response to high ammonia exposure.Conclusion: Altogether, our findings not only presented a comprehensive mRNA transcriptome profile of liver after high ammonia exposure, but also found some key genes and TFs that could be used to investigate the toxicity mechanism of high ammonia on livers.

Ammonia exposure induced intestinal inflammation injury mediated by intestinal microbiota in broiler chickens via TLR4/TNF-α signaling pathway

Ammonia is a known environmental pollutant that causes injury to the intestine. Growing evidence suggests that intestinal microbiota dysbiosis involves in the development of intestinal injury under environmental pollution. However, the specific mechanism remains unexplored. To do this, broiler chicken ileal exposed to ammonia was selected as the research object. Further, antibiotic depletion of intestinal microbiota and flora transplantation were used to clarify the role of intestinal microbiota in the intestinal injury. Histopathological examination indicated inhaled ammonia caused intestinal injury. Then we observed a decrease in intestinal muc-2, claudin-1, IL-6, IL-10 in ammonia inhalation, as opposed to the control group, associated with a significant increase in TLR4, MyD88, NF-κB, TNF-α, IL-1β, caspase3. Moreover, there was a significant increase of Streptococcus, Escherichia-Shigella, Faecalibacterium, [Ruminococcus]_torques_group, Ruminococcaceae_UCG-014, unclassified_f_Lachnospiraceae, Rothia, unclassified_f_Ruminococcaceae in the inhaled ammonia exposure. Correlation analysis suggested that the altered genera were positively correlated with the expression of TLR4 and TNF-α. Moreover, transferring intestinal microbiota from ammonia exposure broiler into healthy broiler caused intestinal injury and increased TLR4 and TNF-α concentrations in recipient broiler. Furthermore, antibiotic depletion of intestinal microbiota attenuated ammonia-caused intestinal injury and reduced TLR4 and TNF-α productions. In summary, TLR4/TNF-α signaling pathway was an important regulated mechanism involved in the intestinal injury mediated by intestinal microbiota dysbiosis under inhaled ammonia.

Screening of cashmere fineness-related genes and their ceRNA network construction in cashmere goats

Competitive endogenous RNA (ceRNA) is a transcript that can be mutually regulated at the post-transcriptional level by competing shared miRNAs. The ceRNA network connects the function of protein-encoded mRNA with the function of non-coding RNA, such as microRNA (miRNA), long non-coding RNA (lncRNA), and circular RNA (circRNA). However, compared with the ceRNA, the identification and combined analysis of lncRNAs, mRNAs, miRNAs, and circRNAs in the cashmere fineness have not been completed. Using RNA-seq technology, we first identified the miRNAs presented in Liaoning Cashmere Goat (LCG) skin, and then analyzed the mRNAs, lncRNAs, circRNAs expressed in LCG and Inner Mongolia cashmere goat (MCG) skin. As a result, 464 known and 45 new miRNAs were identified in LCG skin. In LCG and MCG skin, 1222 differentially expressed mRNAs were identified, 170 differentially expressed lncRNAs and 32 differentially expressed circRNAs were obtained. Then, qRT-PCR was used to confirm further the representative lncRNAs, mRNAs, circRNAs and miRNAs. In addition, miRanda predicted the relationships of ceRNA regulatory network among lncRNAs, circRNAs, miRNAs and mRNAs, the potential regulatory effects were investigated by Go and KEGG analysis. Through the screening and analysis of the results, the ceRNA network regulating cashmere fineness was constructed. LncRNA MSTRG14109.1 and circRNA452 were competed with miRNA-2330 to regulated the expression of TCHH, KRT35 and JUNB, which may provide a potential basis for further research on the process of regulating the cashmere fineness.

Effects of dietary inclusion of Radix Bupleuri extract on the growth performance, and ultrastructural changes and apoptosis of lung epithelial cells in broilers exposed to atmospheric ammonia

To explore whether Radix Bupleuri extract (RBE) could protect lung injury of broilers under ammonia (NH3) exposure, 360 one-d-old male broilers were randomly allocated to four groups of six replicates each in a 2 × 2 factorial design with two diets (the basal diet [control; CON] and the basal diet supplemented with RBE [RB]) and two air conditions (normal condition [<2 ppm of NH3; NOR] and NH3 exposure [70 ppm of NH3; NH70]). The RB diet contained 80 mg saikosaponins/kg diet. On day 7, the lung tissues were collected and the lung epithelial cells (LEC) were isolated. Our experimental results showed that the NH3 exposure decreased body weight gain and feed intake irrespective of dietary treatments during days 1 to 7. However, the RBE addition decreased feed consumption to body weight gain ratio in broilers under NH70 conditions. In the LEC of CON-fed broilers under NH70 conditions, Golgi stacks showed the dilation of cisternaes and reduced secretory vesicles, mitochondria enlarged, the inner membrane of mitochondria became obscure, and the cristae of mitochondria ruptured, whereas only a mild enlargement of Golgi cisternaes and the part rupture of mitochondrial cristaes occurred in the LEC of RB-fed broilers under NH70 conditions. The NH3 exposure increased malondialdehyde (MDA) level, but decreased total antioxidant capacity (T-AOC) in the lungs of CON-fed broilers. However, the RBE addition decreased MDA level and increased T-AOC in the lungs of broilers under NH70 conditions. Simultaneously, the NH3 exposure increased apoptotic rate (AR), mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) level in the isolated LEC of CON-fed broilers. The RBE addition decreased AR, MMP, and ROS in the isolated LEC of broilers under NH70 condition. Besides, the NH3 exposure increased mRNA expression of B-cell lymphoma-2 associated X protein (BAX), caspase-3, and tumor necrosis factor α (TNF-α), but increased interferon γ (IFN-γ) mRNA abundance in the lungs of CON-fed broilers. The RBE supplement decreased mRNA levels of BAX, caspase-3, and TNF-α, but increased IFN-γ, interleukin (IL)-4, and IL-17 mRNA levels in the lungs of broilers under NH70 conditions. These results indicated that dietary RBE addition alleviated NH3 exposure-induced intercellular ultrastructural damage via mitochondrial apoptotic pathway, possibly due to RBE-induced increase of antioxidant capacity and immunomodulatory function in the lungs of broilers under NH3 exposure.

Hydrogen sulfide exposure induces pyroptosis in the trachea of broilers via the regulatory effect of circRNA-17828/miR-6631-5p/DUSP6 crosstalk on ROS production

Hydrogen sulfide (H₂S) is an air pollutant to cause tracheal injury. Pyroptosis is responsible for tissue injury through reactive oxygen species (ROS) production. Competitive endogenous RNAs (ceRNAs) chelate microRNAs and reduce their inhibitory effect on other transcripts, thus affecting ROS levels and pyroptosis. However, it is not clear how H₂S regulates pyroptosis via the ceRNA axis. Therefore, we established a broilers model of H₂S exposure for 42 days to assess pyroptosis and obtain a ceRNA network by immunohistochemistry and RNA sequencing. We detected pyroptosis induced by H₂S and verified circRNA-IGLL1-17828/miR-6631-5p/DUSP6 axis by a double luciferase reporter assay. We also measured ROS levels and the expression of pyroptotic indicators such as (Caspase1) Casp-1, Interleukin 1β (IL-1β) and Interleukin 1β (IL-18). miR-6631-5p knockdown decreased pyroptotic indicators induced by H₂S. Overexpression of miR-6631-5p or DUSP6 knockdown stimulated ROS generation and upregulated pyroptotic indicators. N-acetyl-_L-cysteine (NAC) decreased pyroptotic indicators and ROS levels both induced by miR-6631-5p. Moreover, circRNA-IGLL1-17828, participated in intermolecular competition as a ceRNA of DUSP6. In conclusion, circRNA-IGLL1-17828/miR-6631-5p/DUSP6 crosstalk regulated H₂S-induced pyroptosis in broilers trachea via ROS generation. This is the first study to reveal regulation mechanism of circRNA-related CeRNAs on pyroptosis induced by H₂S, providing important reference for environmental toxicology.

Transcriptome analysis reveals that hydrogen sulfide exposure suppresses cell proliferation and induces apoptosis through ciR-PTPN23/miR-15a/E2F3 signaling in broiler thymus

The immune organs, like thymus, are one of the targets of hydrogen sulfide (H₂S). Previously we reported that H₂S induced the differential expression of mRNAs that implicating apoptosis in thymus, however, the roles of noncoding RNAs (ncRNAs) in H₂S-induced thymus injury are still unknown. Pollution gases could alter the expression of ncRNAs, which have been shown to play important roles in many physiological and pathophysiological processes, including immune activity. This study revealed that H₂S exposure induced 9 differentially expressed circRNAs and 15 differentially expressed miRNAs in chicken thymus. Furthermore, the circRNA - miRNA - mRNA network was constructed. We discovered that circR-PTPN23 - miR-15a - E2F3 was involved in the cell cycle and apoptosis. Further, an in vitro H₂S exposure model was established using HD11 cell line and demonstrated that H₂S suppressed cell proliferation and induced apoptosis. Moreover, ciR-PTPN23 and E2F3 were downregulated, but miR-15a was upregulated in both the thymus and HD11 cell line after H₂S exposure. Bioinformatics analysis revealed that ciR-PTPN23 directly bound to miR-15a and that E2F3 was the target gene of miR-15a. Knocking down ciR-PTPN23 suppressed HD11 proliferation and caused G1 arrest and apoptosis, however, this phenomenon could be partially reversed by ciR-PTPN23 overexpression or miR-15a silencing. In summary, the ciR-PTPN23 - miR-15a - E2F3 axis was involved in H₂S-induced cell proliferation suppression and apoptosis.

Th1/Th2 imbalance and heat shock protein mediated inflammatory damage triggered by manganese via activating NF-κB pathway in chicken nervous system in vivo and in vitro

Manganese (Mn) is a ubiquitous heavy metal pollutant in environment, and excess Mn can damage nervous system of humans and animals. However, molecular mechanism of Mn-induced poultry neurotoxicity on inflammatory injury is still not fully clear. Thus, the purpose of the conducted research was to explore molecular mechanism of inflammatory injury caused by Mn in chicken nervous system. Two Mn poisoning models were established in vivo and in vitro. One hundred and eighty chickens were randomly separated into four groups. One control group was raised drinking water and standard diet. Three Mn groups were raised drinking water, and the standard diet supplemented with three different concentrations of MnCl2 ∙ 4H2O. There were 45 birds and 3 replicates in each group. Neurocytes from chicken embryos were cultured in mediums without and with six different concentrations of MnCl2 ∙ 4H2O in vitro. Our experiments showed that excess Mn caused cerebral histomorphological structure alternations and damage, and increased the expressions (P < 0.05) of inflammation-related factor NF-κB, TNF-α, iNOS, COX-2, and PTGEs in vivo and in vitro, meaning that excess Mn caused inflammatory damage and inflammatory response in chicken nervous system. Moreover, there were an upregulated IFN-γ mRNA expression and a downregulated IL-4 mRNA expression (P < 0.05) in bird cerebra and embryonic neurocytes after exposure to Mn, indicating that Mn exposure caused Th1/Th2 imbalance and immunosuppression. Additionally, in our research, the elevation (P < 0.05) of five HSPs (HSP27, HSP40, HSP60, HSP70, and HSP90) was found, suggesting that HSPs participated molecular mechanism of Mn stress. In addition, the inflammatory toxicity of Mn to chicken nervous system was time- and dose-dependent. Taken all together, our findings indicated that Th1/Th2 imbalance and HSPs mediated Mn-caused inflammatory injury via NF-κB pathway in chicken nervous system in vivo and in vitro.

Energy metabolism disorder mediated ammonia gas-induced autophagy via AMPK/mTOR/ULK1-Beclin1 pathway in chicken livers

Ammonia gas is a well-known environmental pollution gas, threatening human health. Ammonia gas is also one of the most harmful gases to livestock and poultry for many years. Many studies have demonstrated toxic effect of ammonia gas on animal health, such as eyes, respiratory system, and digestive system. However, the effect of ammonia gas toxicity on chicken livers and underlying molecular mechanism remains unclear. In this study, we selected chicken liver as research object and duplicated successfully ammonia gas poisoning model of chickens. 1-day-old Ross-308 broilers were randomly divided into the control group (the low ammonia gas group), and two treatment groups (the middle ammonia gas group and the high ammonia gas group) (3 replicates per group and 12 chickens per replicate). Ammonia gas concentration in the low ammonia gas group was ≤5 mg/m³ during day 1-42. Ammonia gas concentration in the middle group was set as 10 ± 0.5 mg/m³ during day 1-21, and 15 ± 0.5 mg/m³ during day 22-42). Ammonia gas concentration in the high ammonia gas group was set as 20 ± 0.5 mg/m³ during day 1-21, and 45 ± 0.5 mg/m³ during day 22-42. The ultrastructure of chicken livers was observed. The activities of four ATPases (Na⁺K⁺-ATPase, Mg⁺⁺-ATPase, Ca⁺⁺-ATPase, and Ca⁺⁺Mg⁺⁺-ATPase), the expression of twelve energy metabolism-related genes (HK1, HK2, PK, PFK, PDHX, CS, LDHA, LDHB, SDHA, SDHB, avUCP, and AMPK), as well as the expression of ten autophagy-related genes (PI3K, LC3I, LC3II, Beclin1, SQSTM1, mTOR, ULK1, ATG5, ATG12, and ATG13) were measured to explore the effect of ammonia gas on energy metabolism and autophagy in chicken livers. Our results showed that excess ammonia gas induced mitochondrial and autophagic damage in chicken liver tissue cells. Meanwhile, ATPases activities were inhibited and the expression of energy metabolism-related genes changed during ammonia gas treatment, meaning that excess ammonia gas caused energy metabolism disorder. Furthermore, ammonia gas exposure altered the expression of autophagy-related genes, suggesting that ammonia gas treatment caused autophagy in chicken livers. Moreover, ammonia gas-induced AMPK compensatory up-regulation activated autophagy process through inhibiting mTOR and promoting ULK1. In addition. there were dose-dependent and time-dependent effects on all detected indexes in ammonia gas-caused chicken liver cell damage. Taken together, AMPK/mTOR/ULK1-Beclin1 pathway participated in energy metabolism disorder-mediated autophagic injury caused by ammonia gas exposure in chicken livers.

Dietary selenomethionine ameliorates lipopolysaccharide-induced renal inflammatory injury in broilers via regulating the PI3K/AKT pathway to inhibit necroptosis

Selenomethionine (SeMet) has antioxidant and anti-inflammatory effects, as a widely used organic Se source in food supplements, and its inhibitory effect on the prevention and treatment of renal inflammatory injury is unclear. Here, in order to explore the protective effect of SeMet on kidney tissue of broilers and determine its potential molecular mechanism, we took broilers as the research object, lipopolysaccharide (LPS) was used as the source of stimulation, and the model was established by adding SeMet to the diet. The histopathological observation indicated that SeMet alleviated the LPS-induced characteristic changes of renal inflammatory injury. Besides, SeMet inhibited LPS-induced PI3K, AKT, caspase 8 and IκB-α downregulation, the necroptosis marker genes (FADD, RIP1, RIP3, MLKL and TNF-α), pro-inflammatory factors (NF-κB, PTGEs, COX-2, iNOS, IL-1β and IL-6) and HSP60, HSP70 and HSP90 overexpression. We concluded that SeMet ameliorates LPS-induced renal inflammatory injury in broilers by inhibiting necroptosis via the regulation of the PI3K/Akt pathway. Thus, we speculated that dietary SeMet may be a potential new strategy for the treatment of renal injury.

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

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

Analysis of miRNA and mRNA reveals core interaction networks and pathways of dexamethasone-induced immunosuppression in chicken bursa of Fabricius

Stress-induced immunosuppression is a serious problem affecting the production value of poultry, but its specific molecular mechanism has not yet been elucidated. We selected 7-day-old Gushi cocks as test animals and successfully established a stress-induced immunosuppression model by injecting 2.0 mg/kg (body weight) dexamethasone (Dex). We then constructed six cDNA libraries and two small RNA libraries of Bursa of Fabricius from the control group and the Dex group. RNA-seq results revealed 21,028 transcripts including 3920 novel transcripts; 500 miRNAs including 68 novel miRNAs were identified. Correlation analysis of miRNA, target genes and mRNA results indicated that the gga-miR-15 family, gga-miR-103-3p, gga-miR-456-3p, and gga-miR-27b-3p, as core differentially expressed miRNAs, may potentially regulate multiple genes which are involved in immune-related pathways; and that the core genes Suppressor of IKBKE 1 (SIKE1) and high mobility group AT-hook 2 (HMGA2) are associated with the miR-17 family (gga-miR-20a-5p, gga-miR-20b-5p, gga-miR-106-5p, and gga-miR-17-5p) and gga-let -7 family (gga-let-7b, gga-let-7i, gga-let-7c-5p, and gga-let-7f-5p). The interaction networks of mRNAs of significantly enrichment pathways and PPI (protein-protein interaction) networks showed that IL6, IL1B, IL8L1, CCL5, SOCS3, SOCS1, ITGB5, GSTA3, SQLE, FDFT1, FN1, IL18, IL10, MAPK11 and MAPK12 are network core nodes and that most of them are strongly associated with immune response. One of the candidate miRNAs, gga-miR-20b-5p, may play an important role in stress-induced immunosuppression. Luciferase assay and over-expression experiments suggested that gga-miR-20b-5p negatively regulated the expression of target gene SIKE1. These results provide better understanding of the mechanism of stress-induced immunosuppression in Gushi chicken bursa, and provide novel targets for subsequent research to improve poultry anti-stress capability.

Comprehensive Analyses of circRNA Expression Profiles and Function Prediction in Chicken Cecums After Eimeria tenella Infection

Coccidiosis is an important intestinal parasitic disease that causes great economic losses to the global poultry production industry. Circular RNAs (circRNAs) are long non-coding RNAs that play important roles in various infectious diseases and inflammatory responses. However, the expression profiles and functions of circRNAs during Eimeria tenella (E. tenella) infection remain unclear. In this study, high-throughput sequencing was carried out to detect circRNAs in chicken cecal tissues from the control (JC), resistant (JR), and susceptible (JS) groups on day 4.5 postinfection (pi), respectively. A total of 104 circRNAs were differentially expressed, including 47 circRNAs between the JS and JC groups, 38 between the JR and JS groups, and 19 between the JR and JC groups. Functional analyses indicated that these differentially expressed circRNAs were involved in pathways related to E. tenella infection; the adaptive immune response was enriched in the JS vs JC group, the NF-kappa B signaling and natural killer cell-mediated cytotoxicity pathways were enriched in the JS vs JC and JR vs JC groups, while the B cell receptor signaling pathway was enriched in only the JR vs JC group. Moreover, the coexpression network of differentially expressed circRNAs and mRNAs suggested that circRNA2202 and circRNA0759 associated with DTX1 in the JS vs JC group, circRNA4338 associated with VPREB3 and CXCL13L3 in the JR vs JC group, and circRNA2612 associated with IL8L1 and F2RL2 in the JR vs JS group were involved in the immune response upon E. tenella infection. In conclusion, our results provide valuable information on the circRNAs involved in the progression of chicken E. tenella infection and advance our understanding of the circRNA regulatory mechanisms of host resistance and susceptibility to E. tenella infection in chickens.

NLRP3 inflammasome is involved in the mechanism of mitigative effect of selenium on lead-induced inflammatory damage in chicken kidneys

Lead (Pb) is a kind of widespread toxic environmental pollutant which can cause harm to organisms. Selenium (Se) has the property of mitigating Pb toxicity through decreasing oxidative stress and inflammation caused by Pb. Nucleotide-binding domain, leucine-rich-containing family, and pyrin-domain containing-3 (NLRP3) inflammasome involve in inflammation process. However, the effect of NLRP3 inflammasome in heavy metal-caused animal damage remains unknown. This research aimed to explore the mechanism of mitigative role of Se on Pb-caused renal inflammatory injury in chickens. One-week-old male chickens were provided a standard diet and drinking water, a standard diet added with 1 mg kg^-1 of Se and drinking water, a standard diet and drinking water added with 350 mg L^-1 Pb, and a standard diet added with 1 mg kg^-1 Se and drinking water added with 350 mg L^-1 Pb. On the 4th, 8th, and 12th weeks, serum was used to measure creatinine (CREA) and uric acid (UA) contents, and kidneys were used to measure Se and Pb concentrations, histological structure, oxidative stress indicators, relative expressions of cytokines, and inflammatory factors. The results showed that Pb accumulated, Se concentration decreased, CREA and UA contents increased, and renal injury occurred in Pb-treated chicken kidneys. Excess Pb increased MDA content and the expressions of IL-1β, IL-6, IL-17, NLRP3, caspase-1, NF-κB, COX-2, TNF-α, and PTGEs and decreased GSH content, GPx and SOD activities, and IFN-γ expression in the chicken kidneys. Se administration alleviated the aforementioned changes. In addition, toxic effect of Pb on the chicken kidneys was time-dependent. NLRP3 inflammasome, caspase-1, and IL-1β may be sensitive indicators in Pb-induced chicken kidney inflammatory damage. In conclusion, NLRP3 inflammasome took part in antagonistic role of Se against Pb-caused inflammation via changing oxidative stress indicators, cytokines, and inflammation-related genes in the chicken kidneys.

Emerging Clues of Regulatory Roles of Circular RNAs through Modulating Oxidative Stress: Focus on Neurological and Vascular Diseases

Circular RNAs (circRNAs) are novel noncoding RNAs that play regulatory roles in gene expression. Dysregulation of circRNAs is associated with the development and progression of several diseases, such as diabetes mellitus, nervous system diseases, cardiovascular diseases, and cancer. CircRNAs functionally participate in cell physiological activities through various molecular mechanisms. However, these molecular mechanisms are unclear. Oxidative stress is an essential factor in the pathogenesis of various diseases, including neurological diseases. Emerging roles of circRNAs have been identified in different systems in response to oxidative stress. In this review, we summarize the current understanding of circRNA biogenesis, properties, expression profiles, and the clues indicating the regulatory roles of circRNAs through oxidative stress in various systems, especially the nervous system.

Inhibition of PI3K/Akt/mTOR pathway by ammonium chloride induced apoptosis and autophagy in MAC-T cell

Ammonia is a harmful gas with a pungent odor, participates in the regulation of a variety of apoptosis and autophagy, which in turn affects the growth and differentiation of cells. To test the regulation of NH₃ on the apoptosis and autophagy of mammary epithelial cells, we selected NH₄Cl as NH₃ donor in vitro model. MTT and CCK-8 assay kits were employed to detect cell activity. Real-time quantitative PCR and western blot methods were used to detect the abundance of inflammatory molecules, apoptosis markers, and autophagy genes. We selected TUNEL kit and the Annexin-FITC/PI method to detect apoptosis. TEM analysis was used to detect autophagic vesicles, and MDC stain evaluated the formation of autophagosome. The results indicated that NH₄Cl reduced cell viability in a concentration-dependent manner and promoted cell inflammatory response, apoptosis, and autophagy. NH₄Cl stimulation notable increased the autophagosomes number. Interestingly, we also detected that the addition of LY294002 and Rapamycin inhibited the PI3K/Akt pathway and the mTOR pathway, respectively, resulting in changes in both apoptosis and autophagy. Therefore, we draw a conclusion that NH₃ may regulate the apoptosis and autophagic response of bovine mammary epithelial cells through the PI3K/Akt/mTOR signaling pathway. Further investigations on ammonia's function in other physiological respects, will be critical to provide theoretical help for the improvement of production performance. It will be also helpful for controlling the harmful gas ammonia concentration in the livestock house to protect the health of dairy cows.

Circular RNAs in Toxicology

Circular RNAs (circRNAs) are a type of closed, long, non-coding RNAs, which have attracted significant attention in recent years. CircRNAs exhibit unique functions and are characterized by stable expression in various tissues across different species. Because the identification of circRNA in plant viroids in 1976, numerous studies have been conducted to elucidate its generation as well as expression under normal and disease conditions. The rapid development of research focused on the roles of circRNAs as biomarkers in diseases such as cancers has led to increased interests in evaluating the effects of toxicants on the human genetics from a toxicological perspective. Notably, increasing amounts of chemicals are generated in the environment; however, their toxic features and interactions with the human body, particularly from the epigenetic viewpoint, remain largely unknown. Considering the unique features of circRNAs as potential prognostic biomarkers as well as their roles in evaluating health risks following exposure to toxicants, the aim of this review was to assess the latest progress in the research concerning circRNA, to address the role of the circRNA-miRNA-mRNA axis in diseases and processes occurring after exposure to toxic compounds. Another goal was to identify the gaps in understanding the interactions between toxic compounds and circRNAs as potential biomarkers. The review presents general information about circRNA (ie, biogenesis and functions) and provides insights into newly discovered exosome-contained circRNA. The roles of circRNAs as potential biomarkers are also explored. A comprehensive review of the available literature on the role of circRNA in toxicological research (ie, chemical carcinogenesis, respiratory toxicology, neurotoxicology, and other unclassified toxicological categories) is included.

The effect of ammonia exposure on energy metabolism and mitochondrial dynamic proteins in chicken thymus: Through oxidative stress, apoptosis, and autophagy

Ammonia (NH₃) gas is an atmospheric pollutant, produced from different sources. In poultry houses NH₃ is produced from the biological process of liter, manure, and protein composition. It has been well documented that NH₃ adversely effects the health of chickens. However, the underlying mechanism of NH₃ toxicity on chicken thymus is still unknown. Thymus is an important immune organ, which play a critical role in eliciting protective immune responses to ensure healing process and elimination of harmful stimuli. The results showed that NH₃ exposure reduced antioxidant activities and induced oxidative stress in thymus tissues. Histological observation showed normal morphology of chicken thymus in control group. In contrast, increased number of nuclear debris, vacuoles, and cristae break were seen in NH₃ affected chickens. Ultrastructural analysis indicated mitochondrial breakdown, disappearance, vacuoles, and chromatin condensation in NH₃ treated groups. The mRNA and protein expression of apoptosis related genes were significantly enhanced in the chicken thymus of NH₃ affected chickens compared to control group. Moreover, Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay results suggested that NH₃ exposure increased positive stained nuclei in the chicken thymus. Meanwhile, NH₃ exposure reduced the number of CD8⁺ T-lymphocytes, decreased the adenosine triphosphate (ATPase) activities. The mRNA and protein expression of autophagy, energy metabolism, and mitochondrial dynamics proteins were altered by NH₃ exposure. In summary, these results showed that NH₃ induced oxidative stress, apoptosis and autophagic cell death (ACD), which could be the possible causes of immune damage and structural impairment in chicken thymus.

PTEN/AKT/mTOR pathway involvement in autophagy, mediated by miR-99a-3p and energy metabolism in ammonia-exposed chicken bursal lymphocytes

Emission of atmospheric ammonia (NH₃) is an environmental challenge because of its harmful effects on humans and animals including birds. Among all organisms, NH₃ is highly sensitive to birds. Autophagy plays a critical role in Bursa of fabricius (BF)-mediated immune responses against various hazardous substances. Therefore, we designed our work to demonstrate whether NH₃ can induce autophagy in broiler chicken BF. In this study, the downregulated levels of mammalian target of rapamycin and light chain-3 (LC-Ⅰ), as well as the upregulated levels of phosphate and tensin homology (PTEN), protein kinase B (AKT), autophagy related-5, light chain-3 (LC3-Ⅱ), Becline-1, and Dynein, were found. Our results of transmission electron microscopy displayed signs of autophagosomes/autophagic lysosomes, and immunofluorescence assay displayed that NH₃ exposure reduced the relative amount of CD8⁺ B-lymphocyte in chicken BF. Exposure of NH₃ led to energy metabolism disturbance by decreasing mRNA levels of glucose metabolism factors aconitase-2, hexokinase-1, hexokinase-2, lactate dehydrogenase-A, lactate dehydrogenase-B, pyruvate kinase, phosphofructokinase and succinate dehydrogenase complex unit-B, and adenosine triphosphates (ATPase) activities (Na⁺/K⁺ ATPase, Ca²⁺ ATPase, Mg²⁺ ATPase, and Ca/Mg²⁺ ATPase). Moreover, phosphate and tensin homology was found as target gene of microRNA-99a-3p which confirmed that high concentration of NH₃ caused autophagy in chicken BF. In summary, these findings suggested that ammonia induced autophagy via miR-99a-3p, the reduction of ATPase activity, and the alteration of autophagy-related factors, and energy metabolism mediation in BF. Our findings provide information to assess the harmful effects of NH₃ on chicken and clues for human health pathophysiology.

Oxidative stress and mitochondrial dysfunction involved in ammonia-induced nephrocyte necroptosis in chickens

Ammonia (NH₃), an environmental pollutant, poses a serious threat to human and avian health. Although previous studies have showed that NH₃ caused kidney injury, the molecular mechanisms of nephrotoxicity induced by NH₃ remain unclear. To explore the mechanisms of NH₃ nephrotoxicity, a total of 36 broiler chicks at one day of age were exposed to NH₃. After 42 days of exposure, blood samples were collected to determine creatinine and uric acid; and kidney samples were weighted and then collected to detect ultrastructural changes, oxidative stress parameters, ATPases, necroptosis- and mitochondrial dynamics-related genes. The results showed that chickens exposed to NH₃ showed lower relative kidney weight and an increase concentration in serum creatinine and uric acid. NH₃ exposure caused nephrocyte necrosis and increased the expression of necroptosis-related genes (TNF-α, RIPK1, RIPK3, MLKL, and JNK). Besides, the activities of antioxidant systems (SOD, CAT, GSH-Px, and T-AOC) were reduced, whereas the concentrations of H₂O₂ and MDA were elevated. Lower activities of ATPases were obtained in NH₃ treatment groups. Furthermore, the mitochondrial fission-related genes drp1 and mff were activated, and mitochondrial fusion-related genes opa1, mfn1 and mfn2 were suppressed after NH₃ exposure. Based on the above results, we conclude that NH₃ caused-oxidative stress and mitochondrial dysfunction mediated nephrocyte necroptosis in chickens. This study may provide new insight into NH₃ nephrotoxicity.

Cooperative application of transcriptomics and ceRNA hypothesis: LncRNA-107052630/miR-205a/G0S2 crosstalk is involved in ammonia-induced intestinal apoptotic injury in chicken

Ammonia (NH₃), as a harmful gas from agricultural production, plays an important role in air pollution, such as haze. Although numerous researchers have paid attention to health damage through NH₃ inhalation, the exhaustive mechanism of NH₃ induced intestinal toxicity remains unclear. A genes crosstalk named competing endogenous RNAs (ceRNA) can explain many regulatory manners from the molecular perspective. However, few studies have attempted to interpret the injury mechanism of air pollutants to the organism via ceRNA theory. Here, we thoroughly investigated the lncRNA-associated-ceRNA mechanism in jejunum samples from a 42-days-old NH₃-exposed chicken model through deep RNA sequencing. We observed the occurrence of apoptosis in jejunum, obtained 46 significantly dysregulated lncRNAs and 30 dysregulated miRNAs, and then constructed lncRNA-associated-ceRNA networks in jejunum. Importantly, a network regulating G0S2 in NH₃-induced apoptosis was discovered. Research results showed that G0S2 was upregulated in jejunum of NH₃-exposed group and was associated with activation of the mitochondrial apoptosis pathway. G0S2 antagonized the anti-apoptotic effect of Bcl2, which could be reversed by miR-205a. Meanwhile, lncRNA-107052630 acted as ceRNA to affect G0S2 function. These data provide new insight for revealing the biological effect of NH₃ toxicity, as well as the environmental research.

The involvement of miR-6615-5p/Smad7 axis and immune imbalance in ammonia-caused inflammatory injury via NF-κB pathway in broiler kidneys

Ammonia (NH₃), a toxic gas, has deleterious effects on chicken health in intensive poultry houses. MicroRNA can mediate inflammation. The complex molecular mechanisms underlying NH₃ inhalation-caused inflammation in animal kidneys are still unknown. To explore the mechanisms, a broiler model of NH₃ exposure was established. Kidney samples were collected on day 14, 28, and 42, and meat yield was evaluated on day 42. We performed histopathological examination, detected miR-6615-5p and mothers against decapentaplegic homolog 7 (Smad7), and determined inflammatory factors and cytokines in kidneys. The results showed that excess NH₃ reduced breast weight and thigh weight, which indicated that excess NH₃ impaired meat yield of broilers. Besides, kidney tissues displayed histopathological changes after NH₃ exposure. Meanwhile, the increases of inducible nitric oxide synthase (iNOS) activity and nitric oxide content were obtained. The mRNA and protein expression of inflammatory factors, including nuclear factor-κB (NF-κB), cyclooxygenase-2, prostaglandin E synthases, and iNOS increased, indicating that NF-κB pathway was activated. T-helper (Th) 1 and regulatory T (Treg) cytokines were downregulated, whereas Th2 and Th17 cytokines were upregulated, suggesting the occurrence of Th1/Th2 and Treg/Th17 imbalances. In addition, we found that Smad7 was a target gene of miR-6615-5p in chickens. After NH₃ exposure, miR-6615-5p expression was elevated, and Smad7 mRNA and protein expression were reduced. In summary, our results suggest that NH₃ exposure negatively affected meat yield; and miR-6615/Smad7 axis and immune imbalance participated in NH₃-induced inflammatory injury via the NF-κB pathway in broiler kidneys. This study is helpful to understand the mechanism of NH₃-induced kidney injury and is meaningful to poultry health and breed aquatics.

NF-κB pathway took part in the development of apoptosis mediated by miR-15a and oxidative stress via mitochondrial pathway in ammonia-treated chicken splenic lymphocytes

Ammonia, a kind of gas with pungent smell, is harmful to livestock and people, and has bad influence on the atmosphere. However, the mechanism of splenic toxicity caused by ammonia is still poorly understood. The aim of present study was to investigate the effect of ammonia on chicken splenic lymphocytes from the perspective of apoptosis. Chicken splenic lymphocytes were divided into the control group and the two ammonium treatment groups (1 mmol/L and 5 mmol/L ammonia), and were cultured for 24 h. CCK-8, flow cytometry (FC), fluorescence microscope, quantitative real-time PCR (qRT-PCR), and Western blot were used to study the differences between different groups. The results showed that ammonia exposure increased the release of calcium (Ca)²⁺ and reactive oxygen species (ROS) from mitochondrion. Besides, we found an increase in mRNA levels of glutathione peroxidase (GPx), inflammation-related genes (nuclear factor-κB (NF-κB), cyclooxygenase-2 (COX-2), inducible nitric (iNOS), tumor necrosis factor-α (TNF-α), and transforming growth factor-β (TGF-β)), apoptosis-related genes (B-cell lymphoma-2 (BCL-2), Bcl-2 associated X protein (BAX), Cytochrome c (Cytc), apoptotic protease activating factor 1 (APAF1), Caspase-9, and Caspase-3), and an increase in protein levels of NF-κB, iNOS, BAX, Cytc, Caspase-9, and Caspase-3. At the same time, we found a decrease level of GPx protein expression, and a decrease level of glutathione S-transferase (GST) mRNA expression, and a decrease level of heme oxygenase-1 (HO-1) and BCL-2 mRNA and protein expression in splenic lymphocytes exposed to ammonia. Meanwhile, miR-15a expression increased under ammonia exposure. In summary, these results indicated that ammonia induced oxidative stress, promoted the release of Ca²⁺, Cytc, and ROS from mitochondria, and then induced mitochondria-mediated inflammatory response, finally triggered apoptosis in chicken splenic lymphocytes.

Ammonia-triggered apoptosis via immune function and metabolic process in the thymuses of chickens by proteomics analysis

Ammonia (NH₃), an environmental pollutant with a pungent odor, is not only an important volatile in fertilizer production and ranching, but also main basic component of haze. In present study, we found that ultrastructural changes and 3167 differentially expressed proteins (DEPs) using proteomics analysis in the thymuses of chickens exposed to NH₃ on day 42. Obtained DEPs were enriched using GO and KEGG; and 66 DEPs took part in immune function, metabolic process, and apoptosis in the thymuses of chickens treated with NH₃. 9 genes of DEPs were validated using qRT-PCR, and mRNA expression of 2 immune-related genes (CTSG and NFATC2), 3 metabolic process-related genes (APOA1, GOT1, and GOLGA3), and 4 apoptosis-related genes (PIK3CD, CTSS, CAMP, and NSD2) were consistent with DEPs in chicken thymuses. Our results indicated that excess NH₃ led to immunosuppression, metabolic disorder, and apoptosis in chicken thymuses. Present study gives a novel insight into the mechanism of NH₃ toxicity and demonstrated that immune response, metabolism process, and apoptosis were important in the mechanism of NH₃ toxicity of chicken exposure to high concentration of NH₃.

Environmental contaminant ammonia triggers epithelial-to-mesenchymal transition-mediated jejunal fibrosis with the disassembly of epithelial cell-cell contacts in chicken

Ammonia (NH₃) is an environmental contaminant that is causing increasing problems with human and animal health due to the development of poultry industry. There are limited studies on the effect of NH₃ inhalation toxicity on the intestinal tract of animals, and underlying molecular mechanisms remain unclear. In the present study, we established a chicken model of NH₃ aspiration-induced injury for 42 days and observed histopathological changes of the jejunum. Tandem mass tag-based quantitative proteomic analysis was applied to investigate changes in the protein profile in the jejunum tissue of chickens that were exposed to NH₃. Overall, 48 significantly differentially expressed proteins (DEPs) were identified. GO and KEGG analyses revealed that most DEPs were closely related to epithelial-to-mesenchymal transition (EMT), cell-cell junctions, and fibrosis-related factors. Regarding fibrosis, type I collagen and fibronectin were significantly increased. With respect to EMT, epithelial marker proteins (such as E-cadherin and keratin) were repressed, while mesenchymal marker proteins (such as vimentin) were activated. Loss of epithelial cell-cell junctions (such as tight junctions, adherens junctions and desmosomes) were observed. Additionally, overexpression of transforming growth factor-beta (TGF-β) may play a key role in the EMT process and fibrosis. Taken together, these findings suggested that NH₃ triggered the EMT and disassembly of epithelial cell-cell contacts, resulting in jejunal fibrosis that was mediated by TGF-β in chickens. The results of our study will contribute to provide a technical reference regarding the research methods of intestinal toxicity of NH₃ and have largely regulatory implications for ecological risk assessment of human health.

Hydrogen sulfide upregulates miR-16-5p targeting PiK3R1 and RAF1 to inhibit neutrophil extracellular trap formation in chickens

Hydrogen sulfide (H₂S) is a toxic air pollutant that causes immune damage. Recent studies have found that neutrophil extracellular trap (NET) formation is one way in which neutrophils exert immune functions. In addition, the formation of NETs is also related to thrombosis and autoimmune diseases. Recent studies have shown that miRNAs are involved in the regulation of a variety of pathophysiological processes. Here, we investigated the role of H₂S in regulating the formation of NETs by affecting miR-16-5p. Our study established an in vitro H₂S exposure model for neutrophils using phorbol-myristate-acetate (PMA) to induce NET formation. We observed the morphological changes of cells with scanning electron microscopy and fluorescence microscopy. Then, the content of extracellular DNA and the expression of MPO and NE in each group were detected. The results showed that H₂S inhibited the formation of NETs. The expression of miR-16-5p and its target genes PiK3R1 and RAF1 was then measured by qRT-PCR. H₂S upregulated miR-16-5p and inhibited expression of the target genes PiK3R1 and RAF1, and it subsequently inhibited the Pi3K/AKT and ERK pathways and decreased respiratory burst levels. Furthermore, H₂S attenuated inositol 1,4,5-trisphosphate receptor (IP3R)-mediated endoplasmic reticulum calcium outflow as well as autophagy caused by PMA. This study enriches H₂S immunotoxicity research and provides a possible solution for the treatment of NET-related diseases.

Ammonia inhalation-induced inflammation and structural impairment in the bursa of fabricius and thymus of broilers through NF-κB signaling pathway

Ammonia (NH₃) is a toxic, environmental pollutant, and irritant gas. Previous studies reported the toxic effects of NH₃ which led to inflammation in various organs of chicken. However, the exact mechanism of NH₃-induced inflammation in chicken lymphoid organs bursa of fabricius (BF) and thymus is still elusive. Thus, this study was designed to investigate NH₃-induced inflammation in chicken BF and thymus. Experimental chickens were divided into low (5.0 mg/m³), middle (10.0-15.0 mg/m³), and high (20.0-45.0 mg/m³) NH₃-treated groups. To investigate NH₃-induced inflammation in chicken's BF and thymus, histological observation, NO content and iNOS activity, inflammatory cytokine contents, and mRNA levels were performed by light microscopy, microplate spectrophotometer, ELISA assay, and qRT-PCR. The finding of the present study showed that NH₃ exposure reduced BF and thymus index, increased nitric oxide (NO) content and inducible nitric oxide synthase (iNOS) activity, inflammatory cytokine contents and mRNA levels of nuclear factor-kappa B (NF-κB), cyclooxygenase-2 (Cox-2), tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), IL-10, IL-1β, IL-18, toll-like receptor 2A (TLR-2A), and iNOS. Histopathological examination revealed signs of inflammation including increased nuclear debris and vacuoles in the cortex and medulla of thymus and bursal follicles. Conclusively, our findings displayed that NH₃ exposure affects the normal function of BF and thymus and led inflammation. The data provided a new ground for NH₃-induced toxicity and risk assessment in chicken production.

miR-187-5p/apaf-1 axis was involved in oxidative stress-mediated apoptosis caused by ammonia via mitochondrial pathway in chicken livers

Ammonia (NH₃), a toxic gas, is an important cause of atmospheric haze and one of the main pollutants in air environment of poultry houses, threatening the health of human beings and poultry. However, little is known about the effect of NH₃ on liver apoptotic damage. This study aimed to investigate the mechanism of oxidative stress-mediated apoptosis caused by NH₃ in chicken livers and whether miR-187-5p/apaf-1 axis was involved in this mechanism. Here we duplicated NH₃ poisoning model of chickens for fattening to study the ultrastructure of chicken livers, apoptosis rate, oxidative stress indexes, miR-187-5p, and apoptosis-related genes. Obvious apoptotic characteristics of liver tissues exposed to excess NH₃ were observed, and the apoptosis rate increased. Excess NH₃ decreased the activities of catalase (CAT), superoxide dismutase (SOD), total antioxidant capacity (T-AOC) and glutathione peroxidase (GSH-Px), and increased the content of malondialdehyde (MDA), suggesting that oxidative stress occurred. miR-187-5p decreased, and apoptotic protease activating factor-1 (apaf-1) increased, indicating that excess NH₃ dysregulated miR-187-5p/apaf-1 axis. The expression of tumor protein p53 (p53), Bcl-2 associated X protein (Bax), Bcl-2 homologous antagonist/killer (Bak), Cytochrome-c (Cyt-c), Caspase-9, Caspase-8, and Caspase-3 was promoted, and the expression of B-cell lymphoma-2 (Bcl-2) was inhibited, resulting in apoptosis. Moreover, oxidative stress indexes, miR-187-5p, and apoptosis-related genes changed in dose- and time-dependent manner. Altogether, miR-187-5p/apaf-1 axis participated in oxidative stress-mediated apoptosis caused by NH₃ via mitochondrial pathway in the livers of chickens for fattening. This study may provide new ideas to study the mechanism of liver apoptotic damage induced by NH₃ exposure.

Selenium alleviates cadmium-induced inflammation and meat quality degradation via antioxidant and anti-inflammation in chicken breast muscles

Cadmium (Cd) as a widespread toxic heavy metal accumulates in animal food including chicken meat through food chain enrichment and finally threatens human health. Selenium (Se) is an essential mineral and possesses antagonistic effects on Cd-induced multiple organs' toxicity in chickens. The objective of the present study was to reveal the antagonistic mechanisms of Se to Cd from the aspects of oxidative stress, inflammation, and meat quality in chicken breast muscles. Firstly, the results showed that Cd significantly elevated the levels of malondialdehyde (MDA), hydrogen peroxide (H₂O₂), and protein carbonyl, and declined the levels of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase (CAT) to trigger oxidative stress in chicken breast muscles. However, Se treatment significantly alleviated Cd-induced oxidative stress by increasing the levels of GSH-Px, SOD, and CAT, and decreasing the levels of MDA, H₂O₂, and protein carbonyl. Secondly, Se obviously inhibited the expressions of Cd-activated inflammation-related genes including tumor necrosis factor (TNF-α), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), inducible nitric oxide synthase (iNOS), prostaglandin-endoperoxide synthase 2 (COX-2), and prostaglandin E synthase (PTGEs) in chicken breast muscles. Thirdly, meat quality-related parameters including pH_45min, ultimate pH (pHu), and drip loss were also detected, and the results showed that Se markedly recovered Cd-induced dropt of pH_45min and increase of drip loss in chicken breast muscles. In brief, these findings demonstrated that Se significantly alleviated Cd-induced oxidative stress and inflammation, and declined meat quality of chicken breast muscles.