Heme oxygenase-1 regulates autophagy through carbon-oxygen to alleviate deoxynivalenol-induced hepatic damage

HO-1-induced autophagy establishes a HO-1-p62-Nrf2 positive feedback loop to reduce gut permeability in cholestatic liver disease

OBJECTIVES

The gut-liver axis disruption is a unified pathogenetic principle of cholestatic liver disease (CSLD). Increased gut permeability is the leading cause of gut-liver axis disruption. HO-1 is capable of protecting against gut-liver axis injury. However, it has rarely been reported whether autophagy is involved in HO-1 protecting gut-liver barrier integrity and the underlying mechanism.

MATERIALS AND METHODS

Mice underwent bile duct ligation (BDL) was established as CSLD model in vivo. Caco-2 cells with LPS treatment was established as in vitro cell model. Immunofluorescence, western blot and transepithelial electrical resistance (TER) assay were used to observe epithelial tight junction (TJ) and autophagy. Liver injury and fibrosis were evaluated as well through H&E staining, masson staining, sirius red staining and ELISA.

RESULTS AND CONCLUSIONS

Our study demonstrated that the epithelial TJ and TER were notably reduced both in BDL mice and in LPS treated intestinal epithelial cells. Increased HO-1 expression could significantly induce intestinal epithelial cell autophagy. Additionally, this increased autophagy level reversed the reduction effects of BDL or LPS on epithelial TJ and TER in vivo and in vitro, therefore decreased transaminase level in serum and relieved liver fibrosis in BDL mice. Besides, increased autophagy level in turn upregulated the expression of HO-1 by p62 degradation of Keap1 and subsequent activation of Nrf2 pathway. Collectively, these results indicate that HO-1 reduces gut permeability by enhancing autophagy level in CSLD, the increased autophagy establishes a HO-1-p62-Nrf2 positive feedback loop to further improve gut-liver axis disruption. Therefore, our study confirms the critical role of autophagy in HO-1 ameliorating gut-liver axis injury during CSLD, highlighting HO-1 as a promising therapeutic target.

The immune function of heme oxygenase-1 (HO-1) from Nile tilapia (Oreochromis niloticus) in response to bacterial infection

Heme oxygenase-1 (HO-1), an inducible rate-limiting metabolic enzyme, exerts critical immunomodulatory functions by potential anti-oxidant, anti-inflammatory, and anti-apoptotic activities. Although accumulative studies have focused on the immune functions of HO-1 in mammals, the roles in fish are poorly understood, and the reports on involvement in the defensive and immune response are very limited. In this study, On-HO-1 gene from Oreochromis niloticus was successfully cloned and identified, which contained an open reading frame (ORF) of 816 bp and coded for a protein of 271 amino acids. The On-HO-1 protein phylogenetically shared a high homology with HO-1 in other teleost fish (76.10%-98.89 %) and a lowly homology with HO-1 in mammals (38.98%-41.55 %). The expression levels of On-HO-1 were highest in the liver of healthy tilapias and sharply induced by Streptococcus agalactiae or Aeromonas hydrophila. Besides, On-HO-1 overexpression significantly increased non-specific immunological parameters in serum during bacterial infection, including LZM, SOD, CAT, ACP, and AKP. It also exerted anti-inflammatory and anti-apoptotic effects in response to the immune response of the infection with S. agalactiae or A. hydrophila by upregulating anti-inflammatory factors (IL-10, TGF-β), autophagy factors (ATG6, ATG8) and immune-related pathway factors (P65, P38), and down-regulating pro-inflammatory factors (IL-1β, IL-6, TNF-α), apoptotic factors (Caspase3, Caspase9), pyroptosis factor (Caspase1), and inflammasome (NLRP3). These results suggested that On-HO-1 involved in immunomodulatory functions and host defense in Nile tilapia.

Hesperidin Alleviates Hepatic Injury Caused by Deoxynivalenol Exposure through Activation of mTOR and AKT/GSK3β/TFEB Pathways

Deoxynivalenol (DON) is a common agricultural mycotoxin that is chemically stable and not easily removed from cereal foods. When organisms consume food made from contaminated crops, it can be hazardous to their health. Numerous studies in recent years have found that hesperidin (HDN) has hepatoprotective effects on a wide range of toxins. However, few scholars have explored the potential of HDN in attenuating DON-induced liver injury. In this study, we established a low-dose DON exposure model and intervened with three doses of HDN, acting on male C57 BL/6 mice and AML12 cells, which served as in vivo and in vitro models, respectively, to investigate the protective mechanism of HDN against DON exposure-induced liver injury. The results suggested that DON disrupted hepatic autophagic fluxes, thereby impairing liver structure and function, and HDN significantly attenuated these changes. Further studies revealed that HDN alleviated DON-induced excessive autophagy through the mTOR pathway and DON-induced lysosomal dysfunction through the AKT/GSK3β/TFEB pathway. Overall, our study suggested that HDN could ameliorate DON-induced autophagy flux disorders via the mTOR pathway and the AKT/GSK3β/TFEB pathway, thereby reducing liver injury.

Low-dose deoxynivalenol exposure inhibits hepatic mitophagy and hesperidin reverses this phenomenon by activating SIRT1

Deoxynivalenol (DON) is by far the most common mycotoxin contaminating cereal foods and feeds. Furthermore, cleaning up DON from contaminated cereal items is challenging. Low-dose DON consumption poses a danger to humans and agricultural animals. The benefits of hesperidin (HDN) include liver protection, anti-oxidative stress, nontoxicity, and a broad range of sources. The study used immunoblotting, immunofluorescence, and transmission electron microscopy to identify factors associated with mitophagy in vitro and in vivo. We demonstrated that low-dose DON exposure inhibited mitophagy in the liver tissue of mice. SIRT1 was a crucial regulator of mitophagy. Moreover, DON stimulated the dephosphorylation of SIRT1 and the acetylation-regulated FOXO3 protein, which resulted in the transcriptional inhibition of FOXO3-driven BNIP3 and compromised the stability of the PINK1 protein mediated by BNIP3. Moreover, HDN's effect was comparable to that of a SIRT1 agonist, which led to a significant decrease in the level of mitophagy inhibition caused by low-dose DON exposure. When combined, these findings suggested that HDN might be a useful treatment approach for liver damage brought on by low-dose DON exposure. Above all, this research will offer fresh perspectives on a viable approach that will encourage further research into risk reduction initiatives for low-dose DON exposure.

Human milk extracellular vesicles enhance muscle growth and physical performance of immature mice associating with Akt/mTOR/p70s6k signaling pathway

Extracellular vesicles (EVs) play an important role in human and bovine milk composition. According to excellent published studies, it also exerts various functions in the gut, bone, or immune system. However, the effects of milk-derived EVs on skeletal muscle growth and performance have yet to be fully explored. Firstly, the current study examined the amino acids profile in human milk EVs (HME) and bovine milk EVs (BME) using targeted metabolomics. Secondly, HME and BME were injected in the quadriceps of mice for four weeks (1 time/3 days). Then, related muscle performance, muscle growth markers/pathways, and amino acids profile were detected or measured by grip strength analysis, rotarod performance testing, Jenner-Giemsa/H&E staining, Western blotting, and targeted metabolomics, respectively. Finally, HME and BME were co-cultured with C2C12 cells to detect the above-related indexes and further testify relative phenomena. Our findings mainly demonstrated that HME and BME significantly increase the diameter of C2C12 myotubes. HME treatment demonstrates higher exercise performance and muscle fiber densities than BME treatment. Besides, after KEGG and correlation analyses with biological function after HME and BME treatment, results showed L-Ornithine acts as a "notable marker" after HME treatment to affect mouse skeletal muscle growth or functions. Otherwise, L-Ornithine also significantly positively correlates with the activation of the AKT/mTOR pathway and myogenic regulatory factors (MRFs) and can also be observed in muscle and C2C12 cells after HME treatment. Overall, our study not only provides a novel result for the amino acid composition of HME and BME, but the current study also indicates the advantage of human milk on skeletal muscle growth and performance.

Cytoprotective Role of Heme Oxygenase-1 in Cancer Chemoresistance: Focus on Antioxidant, Antiapoptotic, and Pro-Autophagy Properties

Chemoresistance remains the foremost challenge in cancer therapy. Targeting reactive oxygen species (ROS) manipulation is a promising strategy in cancer treatment since tumor cells present high levels of intracellular ROS, which makes them more vulnerable to further ROS elevation than normal cells. Nevertheless, dynamic redox evolution and adaptation of tumor cells are capable of counteracting therapy-induced oxidative stress, which leads to chemoresistance. Hence, exploring the cytoprotective mechanisms of tumor cells is urgently needed to overcome chemoresistance. Heme oxygenase-1 (HO-1), a rate-limiting enzyme of heme degradation, acts as a crucial antioxidant defense and cytoprotective molecule in response to cellular stress. Recently, emerging evidence indicated that ROS detoxification and oxidative stress tolerance owing to the antioxidant function of HO-1 contribute to chemoresistance in various cancers. Enhanced HO-1 expression or enzymatic activity was revealed to promote apoptosis resistance and activate protective autophagy, which also involved in the development of chemoresistance. Moreover, inhibition of HO-1 in multiple cancers was identified to reversing chemoresistance or improving chemosensitivity. Here, we summarize the most recent advances regarding the antioxidant, antiapoptotic, and pro-autophagy properties of HO-1 in mediating chemoresistance, highlighting HO-1 as a novel target for overcoming chemoresistance and improving the prognosis of cancer patients.

Induction of autophagy via the ROS-dependent AMPK/mTOR pathway protects deoxynivalenol exposure grass carp hepatocytes damage

Deoxynivalenol (DON) is one of the most frequently found mycotoxin sources in feed and raw food products, endangering human and animal health. The mechanism of grass carp (Ctenopharyngodon idellus) liver cell (L8824) toxicity induced by DON is still unknown. The DON was administered to the L8824 cells in concentrations of 150, 200, and 250 ng/mL for 24 h. The results of this study suggested that DON could enable L8824 cells to significantly increase the levels of autophagy. Concurrently, DON could trigger autophagy through the AMPK-mTOR pathway, which upregulated the expression of p-AMPK and p-ULK1 while downregulating the expression of p-mTOR. In the meantime, DON treatment could alter the levels of expression of the related proteins in autophagy. Additionally, DON treatment dramatically reduced the activity of the antioxidant enzymes as well as increased the levels of oxidase, which increased the production of ROS in L8824 cells. This indicates that DON could induce oxidative stress. Furthermore, we discovered that DON exposure caused apoptosis, which is characterized by elevated levels of BAX, Caspase 9, Caspase 3, and decreased Bcl-2 levels. Next, it was investigated how oxidative stress affected DON-induced autophagy. The research revealed that the oxidative stress inhibitor (NAC) attenuated DON-induced autophagy. Additionally, the study also investigated how autophagy worked under the L8824 cells induced by DON. The ROS production, however, was enhanced by the addition of the autophagy inhibitor (3-MA). Additionally, co-treatment with the apoptosis inhibitor Z-VAD-FMK had no influence on autophagy. The combined findings showed that induction of autophagy via the ROS-dependent AMPK-mTOR pathway protects DON-induced L8824 cells from damage.

Deoxynivalenol induces intestinal injury: insights from oxidative stress and intestinal stem cells

Mycotoxins are fungal secondary metabolites that frequently occur in human and animal diets. Deoxynivalenol (DON) is one of the most widely occurring mycotoxins globally and poses significant harm to the animal husbandry industry and human health. People are increasingly aware of the adverse effects of DON on vulnerable structures and functions in the intestine, especially in the field of intestinal stem cells (ISCs). In this review, we present insights into DON that induces oxidative stress and affects the expansion of ISCs. Related studies of strategies for reducing its harm are summarized. We also discussed promising approaches such as regulation of microbiota, molecular docking, and modulation of the redox status via reducing the expression of Keap1 protein and single-cell sequencing, which may be critical for further revealing the mechanism of DON that induces oxidative stress and affects the expansion of ISCs.

Dietary taurine supplementation counteracts deoxynivalenol-induced liver injury via alleviating oxidative stress, mitochondrial dysfunction, apoptosis, and inflammation in piglets

Deoxynivalenol (DON), as a widespread Fusarium mycotoxin in cereals, food products, and animal feed, is detrimental to both human and animal health. The liver is not only the primary organ responsible for DON metabolism but also the principal organ affected by DON toxicity. Taurine is well known to display various physiological and pharmacological functions due to its antioxidant and anti-inflammatory properties. However, the information regarding taurine supplementation counteracting DON-induced liver injury in piglets is still unclear. In our work, twenty-four weaned piglets were subjected to four groups for a 24-day period, including the BD group (a basal diet), the DON group (3 mg/kg DON-contaminated diet), the DON+LT group (3 mg/kg DON-contaminated diet + 0.3% taurine), and the DON+HT group (3 mg/kg DON-contaminated diet + 0.6% taurine). Our findings indicated that taurine supplementation improved growth performance and alleviated DON-induced liver injury, as evidenced by the reduced pathological and serum biochemical changes (ALT, AST, ALP, and LDH), especially in the group with the 0.3% taurine. Taurine could counteract hepatic oxidative stress in piglets exposed to DON, as it reduced ROS, 8-OHdG, and MDA concentrations and improved the activity of antioxidant enzymes. Concurrently, taurine was observed to upregulate the expression of key factors involved in mitochondrial function and the Nrf2 signaling pathway. Furthermore, taurine treatment effectively attenuated DON-induced hepatocyte apoptosis, as verified through the decreased proportion of TUNEL-positive cells and regulation of the mitochondria-mediated apoptosis pathway. Finally, the administration of taurine was able to reduce liver inflammation due to DON, by inactivating the NF-κB signaling pathway and declining the production of pro-inflammatory cytokines. In summary, our results implied that taurine effectively improved DON-induced liver injury. The underlying mechanism should be that taurine restored mitochondrial normal function and antagonized oxidative stress, thereby reducing apoptosis and inflammatory responses in the liver of weaned piglets.

The circadian rhythm gene Bmal1 ameliorates acute deoxynivalenol-induced liver damage

Deoxynivalenol (DON) is widely emerging in various grain crops, milk, and wine products, which can trigger different toxic effects on humans and animals by inhalation or ingestion. It also imposes a considerable financial loss on the agriculture and food industry each year. Previous studies have reported acute and chronic toxicity of DON in liver, and liver is not only the main detoxification organ for DON but also the circadian clock oscillator directly or indirectly regulates critical physiologically hepatic functions under different physiological and pathological conditions. However, researches on the association of circadian rhythm in DON-induced liver damage are limited. In the present study, mice were divided into four groups (CON, DON, Bmal1^OE, and Bmal1^OE + DON) and AAV8 was used to activate (Bmal1) expression in liver. Then mice were gavaged with 5 mg/kg bw/day DON or saline at different time points (ZT24 = 0, 4, 8, 12, 16, and 20 h) in 1 day and were sacrificed 30 min after oral gavage. The inflammatory cytokines, signal transducers, and activators of transcription Janus kinase/signal transducers and activator of transcription 3 (JAKs/STAT3) pathway and bile acids levels were detected by enzyme-linked immunosorbent assay (ELISA), western blotting, and target metabolomics, respectively. The DON group showed significantly elevated interleukin-1β (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor-α (TNF-α) levels (P < 0.05 for both) and impaired liver function with rhythm disturbances compared to the CON and Bmal1^OE groups. At the molecular level, expressions of some circadian clock proteins were significantly downregulated (P < 0.05 for both) and JAKs/STAT3 pathway was activated during DON exposure, accompanied by indicated circadian rhythm disturbance and inflammatory damage. Importantly, Bmal1 overexpression attenuated DON-induced liver damage, while related hepatic bile acids such as cholic acid (CA) showed a decreasing trend in the DON group compared with the CON group. Our study demonstrates a novel finding that Bmal1 plays a critical role in attenuating liver damage by inhibiting inflammatory levels and maintaining bile acids levels under the DON condition. Therefore, Bmal1 may also be a potential molecular target for reducing the hepatotoxic effects of DON in future studies.

Dihydroartemisinin alleviates deoxynivalenol induced liver apoptosis and inflammation in piglets

Deoxynivalenol (DON) is one of the mycotoxins that contaminate cereals and feed, thereby endangering human and animal health. Dihydroartemisinin (DHA), a derivative of artemisinin, has anti-inflammatory and antioxidant functions in addition to anti-malaria and anti-cancer. The purpose of this study was to investigate the effects of DHA on alleviating liver apoptosis and inflammation induced by DON in piglets. The experimental design followed a 2 (normal diet and DON-contaminated diet) × 2 (with and without supplementation of DHA) factorial arrangement. 36 weaned piglets were subjected to a 21-day experiment. Results showed that DON increased ALT activity, the levels of TNF-α, IL-1β and IL-2, and reduced the levels of total protein (TP) and albumin (ALB) in the serum. However, DHA decreased the levels of TNF-α, IL-1β and IL-2, and increased the levels of TP and ALB. Also, DON decreased glutathione (GSH) content and catalase (CAT) activity, and increased methane dicarboxylic aldehyde (MDA) content. But GSH content was increased by DHA. In addition, DHA decreased DON-induced increase in apoptosis rate of hepatocytes. Furthermore, DON activated death receptor pathway to promote apoptosis by up-regulating the protein expression of FasL and caspase-3, and the mRNA expression of FasL, TNFR1, caspase-8, Bid, Bax, CYC and caspase-3. However, DHA reduced caspase-3 protein expression, as well as the mRNA expression of FADD, Bid, Bax, CYC and caspase-3. Besides, DON also activated TNF/NF-κB pathway to induce an inflammatory response by up-regulating TNF-α protein expression, and the mRNA expression of TNFR1, RIP1, IKKβ, IκBα, IL-1β and IL-8. Nevertheless, DHA reduced the mRNA expression of RIP1, IκBα, NF-κB, IL-1β and IL-6, and the protein expression of TNF-α and NF-κB. In conclusion, DHA improved DON-induced negative effects on serum biochemical parameters and inflammatory cytokine levels, hepatic antioxidant capacity, hepatic apoptosis and inflammation.

Cytochrome P450 enzymes mediated by DNA methylation is involved in deoxynivalenol-induced hepatoxicity in piglets

Deoxynivalenol (DON) is an inevitable contaminant in animal feed and can lead to liver damage, then decreasing appetite and causing growth retardation in piglets. Although many molecular mechanisms are related to hepatoxicity caused by DON, few studies have been done on cytochrome P450 (CYP450) enzymes and DNA methylation. To explore the role of CYP450 enzymes and DNA methylation in DON-induced liver injury, male piglets were fed a control diet, or diet containing 1.0 or 3.0 mg/kg DON for 4 weeks. DON significantly raised the activity of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and glutamyl transpeptidase (GGT) (P < 0.01), leading to liver injury. In vivo study found that DON exposure increased the expression of CYP450 enzymes (such as CYP1A1, CYP2E1, CYP3A29) (P < 0.05), and disturbed the expression of nicotinamide N-methyltransferase (NNMT), galanin-like peptide (GALP) and insulin-like growth factor 1 (IGF-1) (P < 0.05), in which DNA methylation affected the expression of these genes. In vitro study (human normal hepatocytes L02) further proved that DON elevated the expression of CYP1A1, CYP2E1 and CYP3A4 (P < 0.05), and inhibited cell growth in a dose-dependent manner, resulting in cell necrosis. More importantly, knockdown of CYP1A1 or CYP2E1 could alleviate DON-induced growth inhibition by promoting IGF-1 expression. Taken together, increased CYP450 enzymes expression was one of the mechanisms of hepatoxicity and growth inhibition induced by DON, suggesting that the decrease of CYP450 enzymes can antagonize the hepatoxicity in animals, which provides some value for animal feed safety.

Deoxynivalenol induces apoptosis and autophagy in human prostate epithelial cells via PI3K/Akt signaling pathway

Phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway is one of the most deregulated signaling pathway in prostate cancer. It controls basic processes in cells: cell proliferation and death. Any disturbances in the balance between cell death and survival might result in carcinogenesis. Deoxynivalenol (DON) is one of the most common mycotoxins, a toxic metabolites of fungi, present in our everyday diet and feed. Although previous studies reported DON to induce oxidative stress, modulate steroidogenesis, DNA damage and cell cycle modulation triggering together its toxicity, its effect on normal prostate epithelial cells is not known. The aim of the study was to evaluate the effect of DON on the apoptosis and autophagy in normal prostate epithelial cells via modulation of PI3K/Akt signaling pathway. The results showed that DON in a dose of 30 µM and 10 µM induces oxidative stress, DNA damage and cell cycle arrest in G2/M cell cycle phase. The higher concentration of DON induces apoptosis, whereas lower one autophagy in PNT1A cells, indicating that modulation of PI3K/Akt by DON results in the induction of autophagy triggering apoptosis in normal prostate epithelial cells.

The Protective Effect of Heme Oxygenase-1 on Liver Injury Caused by DON-Induced Oxidative Stress and Cytotoxicity

Deoxynivalenol (DON) is a kind of Fusarium toxin that can cause a variety of toxic effects. Oxidative stress and DNA damage play a critical role in the toxicity of DON. However, previous studies focused more on acute toxicity in vivo/vitro models and lacked subchronic toxicity study in vivo. The potentially harmful effect of DON given at doses comparable to the daily human consumption in target organs, especially the liver, which is the main detoxification organ of DON, is also still not fully understood. Otherwise, Heme Oxygenase-1 (HO-1) has also reduced cell damage under the DON condition according to our previous study. Therefore, we used a rodent model that mimicked daily human exposure to DON and further explored its mechanism of toxic effects on liver tissue and Hepa 1–6 cell line. We also used adeno-associated virus (AAV)-modified HO-1 expressing by tail vein injection and constructed lentivirus-Hepa 1–6 cell line for mimicking HO-1 protective ability under the DON condition. The main results showed that both 30 d and 90 d exposures of DON could cause low-grade inflammatory infiltration around hepatic centrilobular veins. The reactive oxygen species (ROS) and 8-hydroxy-2 deoxyguanosine (8-OHdG) increased during DON exposure, indicating oxidation stress and DNA damage. Significantly, AAV-mediated liver-specific overexpression of HO-1 reduced DON-induced liver damage and indirectly protected the abilities of antioxidant enzyme/DNA damage repair system, while AAV-mediated silence of HO-1 produced the opposite effect. In addition, we found that overexpression of HO-1 could enhance autophagy and combined it with an antioxidant enzyme/DNA damage repair system to inhibit DON-induced hepatocyte damage. Altogether, these data suggest that HO-1 reduces the oxidative stress and DNA damage caused by DON sub-chronic exposure through maintaining DNA repair, antioxidant activity, as well as autophagy.

Deoxynivalenol exposure induces liver damage in mice: Inflammation and immune responses, oxidative stress, and protective effects of Lactobacillus rhamnosus GG

Deoxynivalenol (DON), one of the most common environmental pollutants, substantially affects human and animal health. Much attention has been paid to the ability of probiotics to modulate inflammation and immune responses. In this work, the toxic effects of DON on the liver and the protective effects of Lactobacillus rhamnosus GG (LGG) were investigated. We treated mice with oral gavage of DON (2.4 mg/kg bw/day), LGG (1 × 10⁹ CFU/mouse/day) or both for 28 days. The results showed that DON triggered liver inflammation, reflected by pathological changes and liver function damage but LGG oral administration significantly attenuated these changes. Notably, DON treatment activated the TLR4/NF-κB signaling pathway which contribute to produce inflammatory cytokines, but oral administration of LGG inhibited all the effects of DON. DON treatment can also induce oxidative stress and activate Keap1-Nrf2 signaling pathway, leading to the activation of Nrf2 and the downstream genes, while LGG treatment can improve the antioxidant capacity of liver and protected mice from DON injury. In conclusion, LGG was able to negate the detrimental effects of DON on the liver and may contribute as a potential dietary intervention strategy to reduce mycotoxicity.

Hepatotoxicity of food-borne mycotoxins: molecular mechanism, anti-hepatotoxic medicines and target prediction

Mycotoxins are metabolites produced by fungi. The widespread contamination of food and feed by mycotoxins is a global food safety problem and a serious threat to people's health. Most food-borne mycotoxins have strong hepatotoxicity. However, no effective methods have been found to prevent or treat Mycotoxin- Induced Liver Injury (MILI) in clinical and animal husbandry. In this paper, the molecular mechanisms and potential anti-MILI medicines of six food-borne MILI are reviewed, and their targets are predicted by network toxicology, which provides a theoretical basis for further study of the toxicity mechanism of MILI and the development of effective strategies to manage MILI-related health problems in the future and accelerate the development of food safety.

Hypoxia, oxidative stress, and immune evasion: a trinity of the trichothecenes T-2 toxin and deoxynivalenol (DON)

T-2 toxin and deoxynivalenol (DON) are type A and B trichothecenes, respectively. They widely occur as pollutants in food and crops and cause a series of toxicities, including immunotoxicity, hepatotoxicity, and neurotoxicity. Oxidative stress is the primary mechanistic basis of these toxic effects. Increasing amounts of evidence have shown that mitochondria are significant targets of apoptosis caused by T-2 toxin- and DON-induced oxidative stress via regulation of Bax/B-cell lymphoma-2 and caspase-3/caspase-9 signaling. DNA methylation and autophagy are involved in oxidative stress related to apoptosis, and hypoxia and immune evasion are related to oxidative stress in this context. Hypoxia induces oxidative stress by stimulating mitochondrial reactive oxygen species production and regulates the expression of cytokines, such as interleukin-1β and tumor necrosis factor-α. Programmed cell death-ligand 1 is upregulated by these cytokines and by hypoxia-inducible factor-1, which allows it to bind to programmed cell death-1 to enable escape of immune cell surveillance and achievement of immune evasion. This review concentrates on novel findings regarding the oxidative stress mechanisms of the trichothecenes T-2 toxin and DON. Importantly, we discuss the new evidence regarding the connection of hypoxia and immune evasion with oxidative stress in this context. Finally, the trinity of hypoxia, oxidative stress and immune evasion is highlighted. This work will be conducive to an improved understanding of the oxidative stress caused by trichothecene mycotoxins.

Heme Oxgenase-1, a Cardinal Modulator of Regulated Cell Death and Inflammation

Heme oxygenase catalyzes the rate-limiting step in heme degradation in order to generate biliverdin, carbon monoxide (CO), and iron. The inducible form of the enzyme, heme oxygenase-1 (HO-1), exerts a central role in cellular protection. The substrate, heme, is a potent pro-oxidant that can accelerate inflammatory injury and promote cell death. HO-1 has been implicated as a key mediator of inflammatory cell and tissue injury, as validated in preclinical models of acute lung injury and sepsis. A large body of work has also implicated HO-1 as a cytoprotective molecule against various forms of cell death, including necrosis, apoptosis and newly recognized regulated cell death (RCD) programs such as necroptosis, pyroptosis, and ferroptosis. While the antiapoptotic potential of HO-1 and its reaction product CO in apoptosis regulation has been extensively characterized, relatively fewer studies have explored the regulatory role of HO-1 in other forms of necrotic and inflammatory RCD (i.e., pyroptosis, necroptosis and ferroptosis). HO-1 may provide anti-inflammatory protection in necroptosis or pyroptosis. In contrast, in ferroptosis, HO-1 may play a pro-death role via enhancing iron release. HO-1 has also been implicated in co-regulation of autophagy, a cellular homeostatic program for catabolic recycling of proteins and organelles. While autophagy is primarily associated with cell survival, its occurrence can coincide with RCD programs. This review will summarize the roles of HO-1 and its reaction products in co-regulating RCD and autophagy programs, with its implication for both protective and detrimental tissue responses, with emphasis on how these impact HO-1 as a candidate therapeutic target in disease.