Bacillus licheniformis ameliorates Aflatoxin B1-induced testicular damage by improving the gut-metabolism-testis axis

AFB1 exacerbates testicular and intestinal inflammation by increasing stearoyl ethanolamide and homocysteine levels

In environmental toxicology, aflatoxin B1 (AFB1) is recognized for its detrimental effects on reproductive and intestinal health. This study elucidates how AFB1-induced elevations in stearoyl ethanolamide (SEA) and homocysteine (HCY) impact male fertility and intestinal function in mice. AFB1 was found to markedly reduce sperm concentration and exacerbate sperm damage in mice, primarily by increasing serum SEA and HCY levels. These metabolites compromise testicular structure and function, disrupt the blood-testicular barrier, and downregulate critical testicular proteins including DAZL, SYCP1, SYCP2, StAR, and CYP17A1. Transcriptomic analysis revealed that SEA and HCY broadly alter testicular gene expression, activate NOD-like receptor signaling pathways, induce testicular inflammation, and promote apoptosis. Additionally, SEA and HCY impair intestinal barrier function by reducing the expression of tight junction proteins ZO-1 and Occludin. Functional network analysis indicated that SEA and HCY regulate intestinal immune responses by promoting M1 macrophage polarization and the upregulation of pro-inflammatory cytokines, while simultaneously inhibiting anti-inflammatory factors. This study underscores the multifaceted adverse effects of SEA and HCY on male reproductive health and gut integrity, and highlights the need for further research into mechanisms and potential interventions to mitigate these harmful outcomes.

Magnolol protects C6 glioma cells against neurotoxicity of FB1 via modulating PI3K/Akt and mitochondria-associated apoptosis signaling pathways

Fumonisin B1 (FB1) is a contaminant commonly occurring in crops and food. Mycotoxin contamination, including FB1, has been progressively shown to be an important risk factor in mediating neurotoxicity and neurodegenerative diseases. Studies have found that magnolol (MAG) exhibits favorable pharmacological effects in the central nervous system. However, the protective effects of MAG against FB1-induced neurotoxicity and the molecular pathways involved have not been fully elucidated. Our study aimed to investigate the neuroprotective effects of MAG on FB1-exposed C6 cells and to identify the underlying mechanisms. A model of FB1-induced cytotoxicity in C6 glial cells was established. C6 cells were treated with MAG (40, 80 and 160 μM) in the presence/absence of FB1 (15 μM) and then assessed for cell viability, cellular and mitochondrial morphology and oxidative stress. The mechanism of action of MAG was revealed using a variety of means including RNA-seq, qRT-PCR, Western blot, immunofluorescence, scanning electron microscopy analysis and agonist validation experiments. Our results indicated that MAG significantly alleviated AFB1-induced C6 astroglial cytotoxicity, as evidenced by elevated cell viability and restoration of overall cellular and mitochondrial morphology. Meanwhile, MAG also alleviated oxidative stress in FB1-exposed C6 cells, with 80 μM MAG showing the best effect. Transcriptome analysis showed that PI3K/Akt and apoptosis involved in it might be the key pathway for MAG to treat FB1 neurotoxicity. MAG suppressed FB1-induced mitochondria-dependent apoptosis in C6 cells, primarily manifested by reduced apoptosis rate and reversal of apoptosis-associated protein expression. It was verified that MAG restored the expression of p-PI3K and p-Akt in FB1-treated cells and reversed the downstream effectors IKKα and NF-κB via measurement of related protein levels. The rescue experiment using Akt pathway activator (SC79) was further confirmed that activation of the PI3K/Akt signaling pathway is an effective strategy for MAG to mitigate FB1-induced cytotoxicity in C6 astroglial cells.

Deoxynivalenol exposure-related male reproductive toxicity in mammals: Molecular mechanisms, detoxification and future directions

An increasing body of evidence indicates that exposure to widespread, environmental and food contaminants such as mycotoxins may cause endocrine disorders and infertility. Deoxynivalenol (DON), which is a toxic secondary metabolite produced by Fusarium fungi, can lead to multiple harmful effects in humans and animals, such as hepatotoxicity, nephrotoxicity, immunotoxicity, gastrointestinal toxicity, neurotoxicity, genetic toxicity and carcinogenicity. Recently, there has been growing concern about DON-induced male infertility. Exposure to DON and its metabolites can damage the structure and function of male reproductive organs, resulting in impairment of gametogenesis and thus impaired fertility. Potential molecular mechanisms involve oxidative stress, inflammatory response, mitochondrial dysfunction, apoptosis, cell cycle arrest, pyroptosis, and ferroptosis. Moreover, several signaling pathways, including nuclear factor-kappa B, mitogen-activated protein kinase, NLR family pyrin domain containing 3, nuclear factor erythroid 2-related factor 2, AMP-activated protein kinase, mitochondrial apoptotic pathways, and microRNAs are involved in these detrimental biological processes. Research has shown that several antioxidants, small-molecule inhibitors, or proteins (such as lactoferrin) supplementation can potentially offer protective effects by targeting these signaling pathways. This review comprehensively summarizes the harmful effects of DON exposure on male reproductive function in mammals, the underlying molecular mechanisms and emphasizes the potential of several small molecules as protective therapeutics. In the further, the systematic risk assessment when DON at environmental exposure doses to human reproductive health, the in-depth and precise molecular mechanism investigation using emerging technologies, and the development of more effective intervention strategies warrant urgent investigation.

Chronic exposure to liquid crystal monomer EBCN at environmentally relevant concentrations induces testicular dysfunction via the gut-testis axis

4-Cyano-4'-ethoxybiphenyl (EBCN) is a representative cyano liquid crystal monomer (LCM). While prior studies have documented the widespread occurrence of LCMs in diverse environmental and biological samples, research on their reproductive effects in vivo remains limited. This study employed 35-day and 70-day exposure models in mice to assess the short-term and long-term effects of environmentally relevant concentrations of EBCN on testicular health. Our findings indicate that EBCN exposure, irrespective of duration, had minimal impact on body weight, testis weight, and testicular organ coefficient. However, it induced dose-dependent reductions in seminiferous tubule area, sperm count, accompanied by decreases in Leydig cells and spermatogenic cells, along with disruptions in sex hormone levels. Moreover, EBCN exposure led to the upregulation of inflammatory factors in serum, partially attributable to the activation of necroptosis-related pathways. Additionally, 16S rRNA sequencing and metabolomic analysis revealed a decline in gut microbiome diversity and a decrease in anti-inflammatory metabolites, specifically L-carnosine, in the intestine, potentially contributing to the observed testicular toxicity. Supplementation with exogenous L-carnosine mitigated EBCN-induced testicular dysfunction by inhibiting the expression of necroptosis-related genes. In conclusion, our study suggests that prolonged EBCN exposure at environmentally relevant concentrations adversely impacts testicular function via the gut-testis axis.

Effect of microcystin-LR on intestinal microbiota, metabolism, and health of zebrafish (Danio rerio)

Microcystin-LR (MC-LR) is typically produced along with the occurrence of cyanobacterial blooms, potentially exerting deleterious effects on intestinal microbiota and health in aquatic animals. To date, the underlying mechanism by which MC-LR affects intestinal health remains elusive. In this study, adult male zebrafish were exposed to MC-LR to assess its impact on the microbiome and metabolome. Histopathological and biochemical results indicated that MC-LR damaged intestinal villi and epithelial cells, induced intestinal barrier injury and inflammatory response. Metabolomics results revealed that MC-LR induced amino acid, carbohydrate, lipid, energy metabolisms dysbiosis, and specifically promoted glycine, serine and threonine metabolism. Metagenomics results demonstrated that MC-LR altered the composition of intestinal microbiota, and microbial function prediction suggested that MC-LR promoted the functions associated with amino acid, lipid, carbohydrate and energy metabolisms. Multiomics and Metorigin analyses jointly confirmed that glycine, serine and threonine metabolism was predominantly regulated by dominant Proteobacteria, Firmicutes, Fusobacteriota and Bacteroidota under MC-LR stress. This study offers a comprehensive perspective on the toxicity of microbiota and microbiota-derived metabolism in fish intestines induced by MC-LR and deepens our comprehension of the disruptive influence of MC-LR on intestinal homeostasis in organisms.

Vitamin B6 Alleviates Aflatoxin B1-Induced Impairment of Testis Development by Activating the PI3K/Akt Signaling Pathway

Aflatoxin B1 (AFB1) is a harmful environmental contaminant known to disrupt gut microbiota and cause health problems. In recent years, the role of vitamin B6 (VB6) in maintaining intestinal and reproductive health has attracted much attention. AFB1 has been found to damage the intestinal barrier and cause inflammation by disrupting the intestinal microbiota, particularly by increasing the abundance of Enterococcus. In mice treated with AFB1, serum metabolites were disturbed, VB6 serum levels were reduced, and testicular inflammation was exacerbated. Enterococcus exposure in mice leads to a reduction in serum VB6 levels, which is accompanied by intestinal and testicular damage. However, VB6 supplementation significantly ameliorated AFB1-induced intestinal and testicular injury. Transcriptomics and Western blotting showed that after AFB1 exposure, VB6 could increase the expression of phosphoinositide 3-kinase (PI3K) and kinase B (AKT) as well as their phosphorylated forms in the testes of mice. Based on the results, AFB1 leads to intestinal and testicular damage by disturbing the gut microbiota, and VB6 represents a potential therapeutic to counteract this damage. In conclusion, supplementation with adequate VB6 can ameliorate AFB1-induced intestinal and testicular damage, emphasizing the importance of VB6 intervention and providing a new perspective for the prevention and treatment of AFB1-related health issues.

Microbiota contribute to regulation of the gut-testis axis in seasonal spermatogenesis

Seasonal breeding is an important adaptive strategy for animals. Recent studies have highlighted the potential role of the gut microbiota in reproductive health. However, the relationship between the gut microbiota and reproduction in seasonal breeders remains unclear. In this study, we selected a unique single food source animal, the flying squirrel (Trogopterus xanthipes), as a model organism for studying seasonal breeding. By integrating transcriptomic, metabolomic, and microbiome data, we comprehensively investigated the regulation of the gut-metabolism-testis axis in seasonal breeding. Here, we demonstrated a significant spermatogenic phenotype and highly active spermatogenic transcriptional characteristics in the testes of flying squirrels during the breeding season, which were associated with increased polyamine metabolism, primarily involving spermine and γ-amino butyric acid. Moreover, an enrichment of Ruminococcus was observed in the large intestine during the breeding season and may contribute to enhanced methionine biosynthesis in the gut. Similar changes in Ruminococcus abundance were also observed in several other seasonal breeders. These findings innovatively revealed that reshaping the gut microbiota regulates spermatogenesis in seasonal breeders through polyamine metabolism, highlighting the great potential of the gut-testis axis in livestock animal breeding and human health management.

Dietary Chlorella vulgaris mitigates aflatoxin B1 toxicity in broiler chicken: Toxicopathological, hematobiochemical and immunological perspectives

Mycotoxins are the chemical substances, produced as the secondary metabolites of some toxigenic species of fungi which cause critical health issues in humans, birds and different animal species while Chlorella vulgaris (CV) is a unicellular microalga which contains plenty of important nutritional ingredients. This study was planned to evaluate the toxicopathological, hematobiochemical and immune changes incurred by dietary supplementation of aflatoxin B1 (AFB1) and their mitigation through CV in broilers. For this study to be conducted, 180 broiler birds of one day old were uniformly distributed into six (06) groups and administered various combinations of AFB1 (200 μg/kg) or CV (0.5 and 1.0%) and the duration of the experiment was 42 days. Parameters deliberated were body weight, feed intake, relative visceral organ weights, gross and histopathological examination, hematological parameters (erythrocytic and leukocytic count, hematocrit and hemoglobin), serum biochemical analysis (serum total proteins, ALT, globulin, albumin, creatinine and urea), humoral response against sheep RBCs, response to subcutaneous injection of phytohemagglutinin-P and phagocytic system function assay. The results of this experiment confirmed that 1.0% CV efficiently mitigated AFB1 induced alterations in the studied parameters while this mitigation was partial when 0.5% CV was used with AFB1. Further studies in this regard are still needed to investigate the exact AFB1:CV ratio responsible for complete amelioration.

Resveratrol Alleviates Fumonisin B1-Induced Cytotoxicity in Sertoli Cells

Fumonisin B1 is a common food contaminant that has been found to adversely affect the reproductive system, especially Sertoli cells. However, the potential mitigation of FB1-induced cytotoxicity in Sertoli cells has not been fully elaborated. Resveratrol is a natural substance with anti-inflammatory, antioxidant, and anti-tumor properties. Herein, the protective effects of resveratrol against FB1-induced cytotoxicity in Sertoli cells were examined in this work. The mouse Sertoli cell line (TM4) was used as a research model. These results indicated that FB1 (40 μM and 80 μM) significantly reduces cell viability, disrupts the cell barrier, and induces an inflammatory response in TM4 cells. To our surprise, resveratrol (15 μM) showed an ability to reverse adverse effects induced by FB1 (40 μM). Furthermore, resveratrol could alleviate the FB1-induced apoptosis, decrease ROS level, and promote the antioxidant enzymes (CAT and SOD2) expression in FB1-treated TM4 cells. The addition of resveratrol could mitigate FB1-induced promoted phosphorylation of JNK and upregulation of c-jun expression. Interestingly, resveratrol was also able to mitigate the cytotoxicity of FB2 (40 μM), FB3 (40 μM), and an FB1-FB2-FB3 (40 μM-40 μM-40 μM) combination group on TM4 cells. In summary, this research displayed that resveratrol may alleviate fumonisin B1-induced cytotoxicity in Sertoli cells via inhibiting oxidative stress-mediated JNK/c-jun signaling pathway-induced apoptosis. This study provides new insights into the prevention and treatment of FB1-induced testicular toxicity and highlights the potential application value of resveratrol.

Enzymatic Oxidation of Aflatoxin M1 in Milk Using CotA Laccase

Aflatoxin M1 (AFM1) in milk poses a significant threat to human health. This study examined the capacity of Bacillus licheniformis CotA laccase to oxidize AFM1. The optimal conditions for the CotA laccase-catalyzed AFM1 oxidation were observed at pH 8.0 and 70 °C, achieving an AFM1 oxidation rate of 86% in 30 min. The Km and Vmax values for CotA laccase with respect to AFM1 were 18.91 μg mL-1 and 9.968 μg min-1 mg-1, respectively. Computational analysis suggested that AFM1 interacted with CotA laccase via hydrogen bonding and van der Waals interactions. Moreover, the oxidation products of AFM1 mediated by CotA laccase were identified as the C3-hydroxy derivatives of AFM1 by HPLC-FLD and UPLC-TOF/MS. Toxicological assessment revealed that the hepatotoxicity of AFM1 was substantially reduced following oxidation by CotA laccase. The efficacy of CotA laccase in removing AFM1 in milk was further tested, and the result showed that the enzyme agent achieved an AFM1 removal rate of 83.5% in skim milk and 65.1% in whole milk. These findings suggested that CotA laccase was a novel AFM1 oxidase capable of eliminating AFM1 in milk. More effort is still needed to improve the AFM1 oxidase activity of CotA laccase in order to shorten the processing time when applying the enzyme in the milk industry.

Aflatoxin Exposure-Caused Male Reproductive Toxicity: Molecular Mechanisms, Detoxification, and Future Directions

Widespread endocrine disorders and infertility caused by environmental and food pollutants have drawn considerable global attention. Aflatoxins (AFTs), a prominent class of mycotoxins, are recognized as one of the key contributors to environmental and food contamination. Aflatoxin B1 (AFB1) is the most potent and toxic pollutant among them and is known to cause multiple toxic effects, including neuro-, nephro-, hepato-, immune-, and genotoxicity. Recently, concerns have been raised regarding AFB1-induced infertility in both animals and humans. Exposure to AFB1 can disrupt the structure and functionality of reproductive organs, leading to gametogenesis impairment in males, subsequently reducing fertility. The potential molecular mechanisms have been demonstrated to involve oxidative stress, cell cycle arrest, apoptosis, inflammatory responses, and autophagy. Furthermore, several signaling pathways, including nuclear factor erythroid 2-related factor 2; NOD-, LRR-, and pyrin domain-containing protein 3; nuclear factor kappa-B; p53; p21; phosphoinositide 3-kinase/protein kinase B; the mammalian target of rapamycin; adenosine 5'-monophosphate-activated protein kinase; and mitochondrial apoptotic pathways, are implicated in these processes. Various interventions, including the use of small molecules, Chinese herbal extracts, probiotic supplementation, and camel milk, have shown efficacy in ameliorating AFB1-induced male reproductive toxicity, by targeting these signaling pathways. This review provides a comprehensive summary of the harmful impacts of AFB1 exposure on male reproductive organs in mammals, highlighting the potential molecular mechanisms and protective agents.

Environmental Heat Stress Decreases Sperm Motility by Disrupting the Diurnal Rhythms of Rumen Microbes and Metabolites in Hu Rams

Heat stress (HS) has become a common stressor, owing to the increasing frequency of extreme high-temperature weather triggered by global warming, which has seriously affected the reproductive capacity of important livestock such as sheep. However, little is known about whether HS reduces sperm motility by inducing circadian rhythm disorders in rumen microorganisms and metabolites in sheep. In this study, the year-round reproduction of two-year-old Hu rams was selected, and the samples were collected in May and July 2022 at average environmental temperatures between 18.71 °C and 33.58 °C, respectively. The experiment revealed that the mean temperature-humidity index was 86.34 in July, indicating that Hu rams suffered from HS. Our research revealed that HS significantly decreased sperm motility in Hu rams. Microbiome analysis further revealed that HS reshaped the composition and circadian rhythm of rumen microorganisms, leading to the circadian disruption of microorganisms that drive cortisol and testosterone synthesis. Serum indicators further confirmed that HS significantly increased the concentrations of cortisol during the daytime and decreased the testosterone concentration at the highest body temperature. Untargeted metabolomics analysis revealed that the circadian rhythm of rumen fluid metabolites in the HS group was enriched by the cortisol and steroid synthesis pathways. Moreover, HS downregulated metabolites, such as kaempferol and L-tryptophan in rumen fluid and seminal plasma, which are associated with promotion of spermatogenesis and sperm motility; furthermore, these metabolites were found to be strongly positively correlated with Veillonellaceae_UCG_001. Overall, this study revealed the relationship between the HS-induced circadian rhythm disruption of rumen microorganisms and metabolites and sperm motility decline. Our findings provide a new perspective for further interventions in enhancing sheep sperm motility with regard to the circadian time scale.

A multi-omics approach reveals that lotus root polysaccharide iron ameliorates iron deficiency-induced testicular damage by activating PPARγ to promote steroid hormone synthesis

Iron deficiency is a common nutritional issue that seriously affects male reproductive health. Lotus root polysaccharide iron (LRPF), a novel nutritional supplement, may ameliorate the damage caused by iron deficiency, however, the mechanism is unclear. In this study, we comprehensively determined the benefits of LRPF on reproduction in iron-deficient mice by integrating transcriptomics, microbiomics and serum metabolomics. Microbiomics showed that LRPF could restore changes to the intestinal microbiota caused by iron deficiency. Metabolomics results showed that LRPF stabilised steroid hormone and fatty acid metabolism in iron-deficient mice, reduced the content of ethyl chrysanthemumate (EC) and ameliorated the reproductive impairment. The transcriptomic analysis showed that LRPF regulated steroid hormone synthesis and the peroxisome proliferator-activated receptor (PPAR) signalling pathway in iron-deficient mice. In vitro experiments showed that LRPF could promote steroid hormone synthesis in Leydig cells by activating PPARγ. In conclusion, this study highlights the advantage of LRPF to improve testicular development.

Multiple omics integration analysis reveals the regulatory effect of chitosan oligosaccharide on testicular development

Infertility is a global health problem affecting millions of people of reproductive age worldwide, with approximately half caused by males. Chitosan oligosaccharide (COS) has strong antioxidant capacity, but its impact on the male reproductive system has not been effectively evaluated. To address this, we integrated RNA-seq, serum metabolomics and intestinal 16 S rDNA analysis to conduct a comprehensive investigation on the male reproductive system. The results showed that COS has potential targets for the treatment of oligospermia, which can promote the expression of meiotic proteins DDX4, DAZL and SYCP1, benefit germ cell proliferation and testicular development, enhance antioxidant capacity, and increase the expression of testicular steroid proteins STAR and CYP11A1. At the same time, COS can activate PI3K-Akt signaling pathway in testis and TM3 cells. Microbiome and metabolomics analysis suggested that COS alters gut microbial community composition and cooperates with serum metabolites to regulate spermatogenesis. Therefore, COS promotes male reproduction by regulating intestinal microorganisms and serum metabolism, activating PI3K-Akt signaling pathway, improving testicular antioxidant capacity and steroid regulation.

The Novel Role of the NLRP3 Inflammasome in Mycotoxin-Induced Toxicological Mechanisms

Mycotoxins are secondary metabolites produced by several fungi and moulds that exert toxicological effects on animals including immunotoxicity, genotoxicity, hepatotoxicity, teratogenicity, and neurotoxicity. However, the toxicological mechanisms of mycotoxins are complex and unclear. The nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome is a multimeric cytosolic protein complex composed of the NLRP3 sensor, ASC adapter protein, and caspase-1 effector. Activation of the NLRP3 inflammasome plays a crucial role in innate immune defence and homeostatic maintenance. Recent studies have revealed that NLRP3 inflammasome activation is linked to tissue damage and inflammation induced by mycotoxin exposure. Thus, this review summarises the latest advancements in research on the roles of NLRP3 inflammasome activation in the pathogenesis of mycotoxin exposure. The effects of exposure to multiple mycotoxins, including deoxynivalenol, aflatoxin B1, zearalenone, T-2 toxin, ochratoxin A, and fumonisim B1, on pyroptosis-related factors and inflammation-related factors in vitro and in vivo and the pharmacological inhibition of specific and nonspecific NLRP3 inhibitors are summarized and examined. This comprehensive review contributes to a better understanding of the role of the NLRP3 inflammasome in toxicity induced by mycotoxin exposure and provides novel insights for pharmacologically targeting NLRP3 as a novel anti-inflammatory agent against mycotoxin exposure.

Pleurotus eryngii polysaccharides alleviate aflatoxin B1-induced liver inflammation in ducks involving in remodeling gut microbiota and regulating SCFAs transport via the gut-liver axis

Aflatoxin B1 (AFB1) is one of the most widespread contaminants in agricultural commodities. Pleurotus eryngii (PE) is widely used as a feed additive for its anti-inflammatory properties, and its major active substance is believed to be polysaccharides. This study aims to explore the underlying mechanism of dietary PE polysaccharides alleviating AFB1-induced toxicity in ducks. The major monosaccharide components of PE polysaccharides were identified as glucose, mannose, galactose, glucuronic acid, and fucose. The results showed that dietary PE polysaccharides could alleviate liver inflammation, alleviate intestinal barrier dysfunction, and change the imbalanced gut microbiota induced by AFB1 in ducks. However, PE polysaccharides failed to exert protective roles on the liver and intestine injury induced by AFB1 in antibiotic-treated ducks. The PE + AFB1-originated microbiota showed a positive effect on intestinal barrier and inflammation, the SCFAs transport via the gut-liver axis, and liver inflammation compared with the AFB1-originated microbiota in ducks. These findings provided a possible mechanism that PE polysaccharides alleviated AFB1-induced liver inflammation in ducks by remodeling gut microbiota, regulating microbiota-derived SCFAs transport via the gut-liver axis, and inhibiting inflammatory gene expressions in the liver, which may provide new insight for therapeutic methods against AFB1 exposure in animals.