Particulate Matter 2.5 Induced Developmental Cardiotoxicity in Chicken Embryo and Hatchling

The Impact of Fine Particulate Matter on Embryonic Development

Airborne fine particulate matter (PM2.5) in air pollution has become a significant global public health concern related to allergic diseases. Previous research indicates that PM2.5 not only affects the respiratory system but may also induce systemic inflammation in various tissues. Moreover, its impact may vary among different populations, with potential consequences during pregnancy and in newborns. However, the precise mechanisms through which PM2.5 induces inflammatory reactions remain unclear. This study aims to explore potential pathways of inflammatory responses induced by PM2.5 through animal models and zebrafish embryo experiments. In this study, zebrafish embryo experiments were conducted to analyze the effects of PM2.5 on embryo development and survival, and mouse experimental models were employed to assess the impact of PM2.5 stimulation on various aspects of mice. Wild-type zebrafish embryos were exposed to a PM2.5 environment of 25-400 μg/mL starting at 6 h after fertilization (6 hpf). At 6 days post-fertilization, the survival rates of the 25, 50, 100, and 200 µg/mL groups were 100%, 80, 40%, and 40%, respectively. Zebrafish embryos stimulated with 25 μg/mL of PM2.5 still exhibited successful development and hatching. Additionally, zebrafish subjected to doses of 25-200 μg/mL displayed abnormalities such as spinal curvature and internal swelling after hatching, indicating a significant impact of PM2.5 stimulation on embryo development. In the mouse model, mice exposed to PM2.5 exhibited apparent respiratory overreaction, infiltration of inflammatory cells into the lungs, elevated levels of inflammatory response-related cytokines, and inflammation in various organs, including the liver, lungs, and uterus. Blood tests on experimental mice revealed increased expression of inflammatory and chemotactic cytokines, and GSEA indicated the induction of various inflammatory responses and an upregulation of the TNF-α/NFκB pathway by PM2.5. Our results provide insights into the harmful effects of PM2.5 on embryos and organs. The induced inflammatory responses by PM2.5 may be mediated through the TNF-α/NFκB pathway, leading to systemic organ inflammation. However, whether PM2.5-induced inflammatory responses in various organs and abnormal embryo development are generated through different pathways requires further study to comprehensively clarify and identify potential treatment and prevention methods.

Astilbin antagonizes developmental cardiotoxicity after cadmium exposure in chicken embryos by inhibiting endoplasmic reticulum stress and maintaining calcium homeostasis

Cadmium (Cd) is a dangerous heavy metal with high toxicity that is known to impair development. Astilbin (ASB) is a protective flavonoid compound. We aimed to explore whether ASB can antagonize the myocardial developmental toxicity of Cd exposure. Cd (2 µg) and/or ASB (0.002 µg) were injected into embryonized eggs that were 1 day old. Histological examinations revealed Cd-induced ventricular dilation, reduced wall thickness, and disrupted myocardial fiber connections, while co-administration of ASB mitigated these effects. Electron microscopy confirmed ASB's ability to counteract Cd-induced myocardial cell myofibril damage. Real-time quantitative PCR (QRT-PCR) and western blot (WB) molecular investigations revealed that Cd increased endoplasmic reticulum stress in myocardial tissue and primary cardiomyocytes, as shown by raised expression of stress-related genes (GRP78, XBP1, GRP94, ATF4, ATF6, IRE1, and CHOP). Moreover, Cd disrupted calcium homeostasis, affecting important genes linked to Ca2+ channels and causing an excess of Ca2+ in the cytoplasm. In addition, we detected genes related to development and differentiation-related genes in myocardial tissue and primary cardiomyocytes. The results showed that the downregulation of transcription factors in the IrxA cluster, Mefs, and Tbxs families after Cd exposure indicated that cardiac transcription was hindered and cardiac markers (TnnT2, TnnC1, Gata4, Gata6, and Nkx2-5) were abnormally expressed. ASB successfully mitigated these disturbances. During the cell cycle, primary cardiomyocytes undergo growth arrest in flow cytometry. These results suggest that the maturation and differentiation of cardiomyocytes are inhibited after Cd exposure, and ASB has an antagonistic effect on Cd. The present study indicated that Cd could trigger developmental cardiotoxicity in chicken embryos and primary cardiomyocytes by endoplasmic reticulum stress and Ca2+ overload, respectively, while ASB has an antagonistic effect.

Exploring the Microbial Community Structure in the Chicken House Environment by Metagenomic Analysis

The environmental conditions of chicken houses play an important role in the growth and development of these animals. The chicken house is an essential place for the formation of microbial aerosols. Microbial aerosol pollution and transmission can affect human and animal health. In this work, we continuously monitored fine particulate matter (PM2.5) in the chicken house environment for four weeks and studied the microbial community structure in the aerosols of the chicken house environment through metagenomic sequencing. Our results found that bacteria, fungi, viruses, and archaea were the main components of PM2.5 in the chicken house environment, accounting for 89.80%, 1.08%, 2.06%, and 0.49%, respectively. Conditional pathogens are a type of bacteria that poses significant harm to animals themselves and to farm workers. We screened ten common conditional pathogens and found that Staphylococcus had the highest relative abundance, while Clostridium contained the most microbial species, up to 456. Basidiomycetes and Ascomycota in fungi showed dramatic changes in relative abundance, and other indexes showed no significant difference. Virulence factors (VF) are also a class of molecules produced by pathogenic microbes that can cause host diseases. The top five virulence factors were found in four groups: FbpABC, HitABC, colibactin, acinetobactin, and capsule, many of which are used for the iron uptake system. In the PM2.5 samples, eight avian viruses were the most significant discoveries, namely Fowl aviadovirus E, Fowl aviadovirus D, Avian leukosis virus, Avian endogenous retrovirus EAV-HP, Avian dependent parvovirus 1, Fowl adenovus, Fowl aviadovirus B, and Avian sarcoma virus. The above results significantly improve our understanding of the microbial composition of PM2.5 in chicken houses, filling a gap on virus composition; they also indicate a potential threat to poultry and to human health. This work provides an important theoretical basis for animal house environmental monitoring and protection.

AHR-mediated m6A RNA methylation contributes to PM2.5-induced cardiac malformations in zebrafish larvae

A growing body of evidence indicates that ambient fine particle matter (PM_2.5) exposure inhibits heart development, but the underlying mechanisms remain elusive. We hypothesized that m⁶A RNA methylation plays an important role in the cardiac developmental toxicity of PM_2.5. In this study, we demonstrated that extractable organic matter (EOM) from PM2.5 significantly decreased global m⁶A RNA methylation levels in the heart of zebrafish larvae, which were restored by the methyl donor, betaine. Betaine also attenuated EOM-induced ROS overgeneration, mitochondrial damage, apoptosis and heart defects. Furthermore, we found that the aryl hydrocarbon receptor (AHR), which was activated by EOM_, directly repressed the transcription of methyltransferases mettl14 and mettl3. EOM also induced genome-wide m⁶A RNA methylation changes, which led us to focus more on the aberrant m⁶A methylation changes that were subsequently alleviated by the AHR inhibitor, CH223191. In addition, we found that the expression levels of traf4a and bbc3, two apoptosis related genes, were upregulated by EOM but restored to control levels by the forced expression of mettl14. Moreover, knockdown of either traf4a or bbc3 attenuated EOM-induced ROS overproduction and apoptosis. In conclusion, our results indicate that PM_2.5 induces m⁶A RNA methylation changes via AHR-mediated mettl14 downregulation, which upregulates traf4a and bbc3, leading to apoptosis and cardiac malformations.

Hexafluoropropylene oxide tetramer acid (HFPO-TeA)-induced developmental toxicities in chicken embryo: Peroxisome proliferator-activated receptor Alpha (PPARα) is involved

Hexafluoropropylene oxide tetramer acid (HFPO-TeA) is an emerging environmental contaminant, with environmental presence but limited toxicological information. To investigate its potential developmental toxicities, various doses of HFPO-TeA exposure were achieved in chicken embryos via air cell injection, and the exposed embryos were incubated until hatch. Within 24 h of hatch, the hatchling chickens were assessed with electrocardiography and histopathology for toxicological evaluation. For mechanistic investigation, in ovo silencing of PPARα was achieved via lentivirus microinjection, then the morphological/functional endpoints along with protein expression levels of PPARα-regulated genes were assessed. HFPO-TeA exposure in chicken embryo resulted in developmental cardiotoxicity and hepatotoxicity. Specifically, decreased right ventricular wall thickness, increased heart rate and hepatic steatosis were observed, whereas silencing of PPARα resulted in alleviation of observed toxicities. Western blotting for EHHADH and FABPs suggested that developmental exposure to HFPO-TeA effectively increased the expression levels of both targets in hatchling chicken heart and liver tissue samples, while PPARα silencing prevented such changes, suggesting that PPARα and its downstream genes are playing critical roles in HFPO-TeA induced developmental toxicities.

PM2.5 induces mitochondrial dysfunction via AHR-mediated cyp1a1 overexpression during zebrafish heart development

Accumulating evidence suggests an association between maternal PM2.5 exposure and congenital heart diseases, but the underlying mechanisms remain unclear. We previously reported that PM2.5 induces cardiac malformations in zebrafish embryos via the aryl hydrocarbon receptor (AHR) pathway, which mediates the generation of reactive oxygen species (ROS). Since mitochondria are not only the main source of ROS but also sensitive to oxidative damage, we hypothesize that mitochondria may play an important role in the cardiac developmental toxicity of PM2.5. In this study, we demonstrated that extractable organic matter (EOM) from PM2.5 caused mitochondrial dysfunction in the heart of zebrafish embryos, including increased mitochondrial ROS (mtROS) levels, mitochondrial permeability transition pore (mPTP) opening, mitochondrial membrane potential (MMP) collapse, reduced mitochondrial ATP levels, and decreased expression levels of the mRNAs encoding mitochondrial proteins, which were attenuated by either pharmacological or genetic inhibition of AHR. We further demonstrated that improving mitochondrial function by inhibiting mPTP opening with Cyclosporin A suppressed the EOM-induced intracellular ROS and mtROS generation, MMP collapse, intrinsic apoptosis, and heart defects. Moreover, the EOM-induced mPTP opening was counteracted by inhibiting mtROS with mitoquinone mesylate (MitoQ). Supplementation with MitoQ also attenuated the EOM-induced mitochondrial dysfunction, apoptosis and heart defects. Additionally, knockdown of cyp1a1 but not cyp1b1 attenuated the EOM-induced mtROS generation and heart defects. Taken together, this study indicates that PM2.5 triggers mtROS generation via AHR-mediated cyp1a1 overexpression, which then causes mPTP opening and mitochondrial dysfunction, leading to apoptosis and heart defects.

Perfluorooctanoic acid-induced developmental cardiotoxicity in chicken embryo: Roles of miR-490-5p

Perfluorooctanoic acid (PFOA) could induce developmental toxicities, affecting various organs, including the heart. Although peroxisome-proliferation activated receptor alpha (PPARα) had been identified as a major target of PFOA, PPARα-independent effects are frequently reported. To further elucidate the mechanism of toxicity in PFOA-induced developmental cardiotoxicity, RNA-seq analysis was performed in hatchling chicken hearts developmentally exposed to vehicle or 2 mg/kg (egg weight) PFOA. RT-PCR and western blotting were then performed to confirm the identified potential targets. Furthermore, lentivirus was designed to overexpress and silence identified target miRNA in developing chicken embryo, and the resulting phenotypes were investigated. 21 miRNAs and 1142 mRNAs were identified to be affected by developmental exposure to PFOA in chicken embryo hearts. Among the identified differentially expressed miRNAs, miR-490-5p was confirmed to be significantly affected by PFOA exposure, along with its downstream targets, Synaptosome associated protein 91 (SNAP91) and LY6/PLAUR domain containing 6 (LYPD6), as indicated by RT-PCR and western blotting results. Lentivirus overexpressing miR-490-5p mimicked the phenotype induced by PFOA exposure, while lentivirus silencing miR-490-5p alleviated PFOA-induced changes. Similar patterns were also observed in the expression of downstream target genes, SNAP91 and LYPD6. In summary, miR-490-5p and its downstream genes, SNAP91 and LYPD6 are associated with PFOA-induced developmental cardiotoxicity in chicken embryo, which might help to further elucidate the mechanism of PFOA-induced developmental cardiotoxicity.

Limosilactobacillus reuteri FN041 prevents atopic dermatitis in pup mice by remodeling the ileal microbiota and regulating gene expression in Peyer’s patches after vertical transmission

Objectives

Limosilactobacillus reuteri FN041 is a potential probiotic bacterium isolated from breast milk in traditional farming and pastoral areas of China. The purpose of this study was to investigate the optimal intervention mode and potential mechanism of FN041 to prevent atopic dermatitis (AD) in mice.

Methods

In intervention mode I, FN041 was supplemented to dams during the late trimester and lactation and pups after weaning; in intervention mode II, FN041 was supplemented after pups were weaned. AD was induced in pups with MC903 plus ovalbumin on the ear after weaning.

Results

The effect of intervention mode I in preventing AD was significantly better than that of intervention mode II. Compared with the model group, the inflammatory response of the pup’s ears, the proportion of spleen regulatory T cells and the plasma IgE were significantly decreased in mice in intervention mode I. Furthermore, the intestinal mucosal barrier was enhanced, and the Shannon index of the ileal microbiota was significantly increased. The microbiota structure deviated from the AD controls and shifted toward the healthy controls according to the PCoA of unweighted UniFrac. The relative abundances of Limosilactobacillus, Faecalibacterium, Bifidobacterium, and Akkermansia in the ileum were significantly increased compared to the AD group. Based on RNA-seq analysis of pups’ Peyer’s patches (PPs), FN041 inhibits autoimmune pathways such as asthma and systemic lupus erythematosus and activates retinol metabolism and PPAR signaling pathways to reduce inflammatory responses. Intervention mode II also significantly reduced AD severity score, but the reduction was approximately 67% of that of intervention mode I. This may be related to its ineffective remodeling of the ileal microbiota.

Conclusion

Prenatal and postnatal administration of FN041 is an effective way to prevent AD in offspring, and its mechanism is related to remodeling of ileal microbiota and PPs immune response.

Mitochondria damage in ambient particulate matter induced cardiotoxicity: Roles of PPAR alpha/PGC-1 alpha signaling

Particulate matter (PM) had been associated with cardiotoxicity, while the mechanism of toxicity has yet to be elucidated, with mitochondria dysfunction as a potential candidate. To investigate the potential cardiotoxic effects of ambient PM exposure and assess the damage to cardiac mitochondria, C57/B6 mice were exposed to filtered air or real ambient PM for three or six weeks. Furthermore, to reveal the role of peroxisome proliferators-activated receptor alpha (PPAR alpha) in PM exposure induced cardiotoxicity/mitochondria damage, animals were also co-treated with PPAR alpha agonist WY 14,643 or PPAR alpha antagonist GW 6471. Cardiotoxicity was assessed with echocardiography and histopathology, while mitochondria damage was evaluated with mitochondria membrane potential measurement and transmission electron microscopy. Potential impacts of PM exposure to PPAR alpha signaling were detected with co-immunoprecipitation and western blotting. The results indicated that exposure to ambient PM exposure induced cardiotoxicity in C57/B6 mice, including altered cardiac functional parameters and morphology. Cardiac mitochondria damage is detected, in the form of compromised mitochondria membrane potential and morphology. Molecular investigations revealed disruption of PPAR alpha interaction with peroxisome proliferator-activated receptor gamma coactivator-1A (PGC-1a) as well as altered expression levels of PPAR alpha downstream genes. Co-treatment with WY 14,643 alleviated the observed toxicities, while co-treatment with GW 6471 had mixed results, exaggerating most cardiotoxicity and mitochondrial damage endpoints but alleviating some cardiac functional parameters. Interestingly, WY 14,643 and GW 6471 co-treatment seemed to exhibit similar regulative effects towards PPAR alpha signaling in animals exposed to PM. In conclusion, ambient PM exposure indeed induced cardiotoxicity in C57/B6 mice, in which cardiac mitochondria damage and disrupted PPAR alpha signaling are contributors.