Piceatannol inhibits oxidative stress through modification of Nrf2-signaling pathway in testes and attenuates spermatogenesis and steroidogenesis in rats exposed to cadmium during adulthood

Oral administration of antimicrobial peptide MPX can effectively regulate LPS-mediated testicular oxidative stress and blood‒testis barrier damage

Oxidative stress and disruption of blood‒testis barrier permeability are considered key factors in the pathogenesis of testicular inflammation, degeneration, and functional impairment, which play crucial roles in male infertility. Antimicrobial peptides (AMPs) are internationally recognized as some of the most promising alternatives to antibiotics. However, the molecular mechanisms by which AMPs regulate oxidative stress and the blood‒testis barrier in the testis are still poorly understood. In this study, we orally administered 0.5 mg/kg antimicrobial peptide MPX (MPX) to mice for 20 and 40 days and evaluated its effects on Lipopolysaccharide LPS-induced testicular oxidative stress and blood‒testis barrier repair, and elucidateed the pharmacokinetics of MPX in mice. The experiment was divided into six groups, control, LPS, MPX, MPX + LPS, Polymyxin and Polymyxin + LPS, respectively. The results showed that oral administration of MPX effectively increased testicular Glutathione (GSH), Total superoxide dismutase (T-SOD), and Catalase (CAT) levels and reduced Nitric oxide (NO) and Malondialdehyde (MDA) levels in the testes and Lactate dehydrogenase (LDH) levels in serum; these findings were consistent with the oxidative stress parameters in the liver. MPX significantly upregulated the expression of Kelch-like ECH-associated protein 1 (Keap1), Nuclear factor erythroid 2-related factor 2 (Nrf2), and Glutamate cysteine ligase, modifier (GLCM) in the testes while downregulating the expression of Glutamate cysteine ligase, catalytic (GCLC) and Inducible nitric oxide synthase (iNOS), thus exerting a regulatory effect on oxidative stress. MPX also effectively increased sperm count and motility and counteracted the LPS-induced blood‒testis barrier damage, and its molecular mechanism involved upregulating the expression of Slug, which subsequently promoted high expression of Claudin, Occludin, Zonula occludens-1 (ZO-1), N-cadherin, and E-cadherin in the testes. After intragastric administration of FITC-MPX for 30 min, FITC-MPX was mainly distributed in the stomach and thoracic cavity, then showed multi-tissue distribution after 30 min. The fluorescence signal could be detected in the testis 1 h later, which confirmed that MPX had testicular targeting. Moreover, both intraperitoneal and intravenous injection of FITC-MPX also confirmed its testicular targeting ability. In conclusion, this study systematically evaluated the long-term effects of the orally administered antimicrobial peptide MPX on oxidative stress and the blood‒testis barrier in the male reproductive system. This study laid the foundation for the antimicrobial peptide MPX to be used in the treatment of male testicular inflammatory diseases.

Piceatannol-Can It Be Used to Treat Hyperpigmentation of the Skin?

Over the years, the cosmetic industry has shifted its focus from synthtic to natural compounds. This change is driven not only by the safety profile of natural ingredients but also by increased consumer awareness about the products they use. As a result, many natural skincare products have been launched in recent years. Hyperpigmentation disorders, such as melasma, age spots (solar lentigines), post-inflammatory hyperpigmentation, freckles, and acanthosis nigricans, are significant concerns. These conditions not only pose pathological issues but also affect individuals' self-esteem. Consequently, treating hyperpigmentation by reducing melanogenesis has become a key area of interest in cosmetology. Among various natural compounds, piceatannol (PCT) shows great potential in treating hyperpigmentation. The primary mechanism previously explored is the inhibition of the tyrosinase enzyme, which is one of the most researched strategies for combating melanogenesis. Additionally, PCT has been shown to downregulate MITF expression, a key gene responsible for the transcription of various melanogenic proteins and enzymes. However, beyond these two mechanisms, little is known about how PCT may inhibit melanogenesis. In this review, we aim to bridge that gap. We will explore and speculate on the possible upstream signaling pathways to MITF, such as Nrf, FOXO3a, CREB, MAPK signaling, etc., where PCT could potentially act to inhibit melanogenesis. This review will not only pave the way for future research related to PCT and hyperpigmentation but also highlight pathways that could be targeted for developing cosmetics and treatments for hyperpigmentation disorders.

Piceatannol Protects Sperm from Cryopreservation Damage by Modulating the Keap1-Nrf2/ARE Signaling Pathway

The purpose of this study was to explore the mechanism of action of Piceatannol (PIC) in attenuating oxidative damage to sperm during cryopreservation. Semen samples were collected and homogenized into six equal parts for freeze-thawing experiments. Four different concentrations of PIC were utilized as cryoprotectants during the freeze-thawing process, maintaing a semen to PIC ratio of 1:1, while sperm motility after freezing and thawing was analyzed using computer-assisted sperm analysis (CASA). Sperm plasma membrane integrity was assessed via the hypo-osmotic swelling (HOS) test. The levels of reactive oxygen species (ROS), superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) activities, long with the ability to scavenge sperm malondialdehyde (MDA), were examined in sperm following the addition of PIC. Quantitative real-time PCR (qRT-PCR) was performed to detect the expression levels of Keap1, Nrf2, GCLC, GCLM, and HMOX1 in sperm. The mechanism by which PIC protects sperm during cryopreservation from oxidative stress damage was further verified. Treatment with PIC at a dose of 5.0 μmol/L significantly improved both sperm motility and viability while effectively reducing ROS levels in frozen sperm. Additionally, the integrity of the sperm plasma membrane was significantly enhanced. Furthermore, the expression level of Keap1 was significantly reduced, whereas the expression levels of GCLC, GCLM, HMOX1, and Nrf2 were significantly increased (p < 0.05) after the addition of PIC. Notably, a significant attenuation of sperm motility and viability was observed in this treatment group when PIC treatment was accompanied by the addition of an Nrf2 inhibitor, resulting in a significant elevation of ROS levels. The finding that PIC modulates ROS in frozen sperm via the Keap1-Nrf2/ARE pathway thereby enhancing sperm viability levels after freezing and thawing provides a novel approach to optimize semen cryopreservation.

Diosgenin protects against cationic bovine serum albumin-induced membranous glomerulonephritis by attenuating oxidative stress and renal inflammation via the NF-κB pathway

CONTEXT

Membranous glomerulonephritis (MGN) is a leading cause of nephrotic syndrome in adults. Diosgenin (DG) has been reported to exert antioxidative and anti-inflammatory effects.

OBJECTIVE

To investigate the renoprotective activity of DG in a cationic bovine serum albumin-induced rat model of MGN.

MATERIALS AND METHODS

Fourty male Sprague-Dawley rats were randomized into four groups. The MGN model was established and treated with a DG dose (10 mg/kg) and a positive control (TPCA1, 10 mg/kg), while normal control and MGN groups received distilled water by gavage for four consecutive weeks. At the end of the experiment, 24 h urinary protein, biochemical indices, oxidation and antioxidant levels, inflammatory parameters, histopathological examination, immunohistochemistry and immunoblotting were evaluated.

RESULTS

DG significantly ameliorated kidney dysfunction by decreasing urinary protein (0.56-fold), serum creatinine (SCr) (0.78-fold), BUN (0.71-fold), TC (0.66-fold) and TG (0.73-fold) levels, and increasing ALB (1.44-fold). DG also reduced MDA (0.82-fold) and NO (0.83-fold) levels while increasing the activity of SOD (1.56-fold), CAT (1.25-fold), glutathione peroxidase (GPx) (1.55-fold) and GSH (1.81-fold). Furthermore, DG reduced Keap1 (0.76-fold) expression, Nrf2 nuclear translocation (0.79-fold), and induced NQO1 (1.25-fold) and HO-1 (1.46-fold) expression. Additionally, DG decreased IL-2 (0.55-fold), TNF-α (0.80-fold) and IL-6 (0.75-fold) levels, and reduced protein expression of NF-κB p65 (0.80-fold), IKKβ (0.93-fold), p-IKKβ (0.89-fold), ICAM-1 (0.88-fold), VCAM-1 (0.91-fold), MCP-1 (0.88-fold) and E-selectin (0.87-fold), and also inhibited the nuclear translocation of NF-κB p65 (0.64-fold).

DISCUSSION AND CONCLUSIONS

The results suggest a potential therapeutic benefit of DG against MGN due to the inhibition of the NF-κB pathway, supporting the need for further clinical trials.

Anacyclus pyrethrum enhances fertility in cadmium-intoxicated male rats by improving sperm functions

BACKGROUND

Environmental pollutants, particularly heavy metals, have been frequently connected to male infertility. Cadmium was previously shown to reduce male fertility by causing oxidative stress. Anacyclus pyrethrum is a well-known medicinal plant. Most of its parts, notably the roots, have excellent antioxidant and anti-inflammatory properties. The present study investigated the potential ability of Anacyclus pyrethrum to protect male rats against cadmium reproductive toxicity.

METHODS

Twenty-eight adult Wistar male rats (8 weeks old) weighing (170-200g) were randomly divided into four groups (n = 7): group (1) the control, group (2) was orally administrated with Anacyclus pyrethrum extract (100mg/kg) for 56 consecutive days, group (3) received a single intraperitoneal (IP) injection of cadmium chloride (1mg/kg), and group (4) received a single IP dose of CdCl2 followed by 8 weeks of oral Anacyclus extract treatment.

RESULTS

Cadmium Cd toxicity resulted in a significant decrease in the concentration of antioxidant enzymes (superoxide dismutase SOD and glutathione peroxidase GPx) in the semen coupled with a significant rise in malondialdehyde MDA level. Consequently, sperm analysis parameters were significantly affected showing decreased motility, viability, concentration and increased morphological aberrations. DNA fragmentation was also detected in the sperms of rats exposed to Cd using comet assay. Serum levels of testosterone T, follicle stimulating hormone FSH, and luteinizing hormone LH were significantly decreased. The mRNA expression levels of sex hormone receptors (FSHR, LHR and AR) in the testis of the Cd exposed rats were significantly decreased. Expression levels of Bax and Bcl2 genes in the sperms of Cd intoxicated rats were also affected shifting the Bax/Bcl2 ratio towards the induction of apoptosis. Co-treatment with the Anacyclus pyrethrum extract restored the oxidative enzymes activities and decreased the formation of lipid peroxidation byproduct, which in turn ameliorated the effect of Cd on sperm parameters, sperm DNA damage, circulating hormone levels, gene expression and apoptosis. These results indicate that Anacyclus pyrethrum could serve as a protective agent against cadmium-induced sperm toxicity.

CONCLUSION

Taken together, it can be concluded that the antioxidant activities of Anacyclus pyrethrum restored the semen quality and enhanced fertility in Cd-intoxicated male rats.

Natural antioxidants mitigate heavy metal induced reproductive toxicity: prospective mechanisms and biomarkers

Heavy metals are harmful environmental pollutants that have attracted widespread attention, attributed to their health hazards to humans and animals. Due to the non-degradable property of heavy metals, organisms are inevitably exposed to heavy metals such as arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg). Several studies revealed that heavy metals can cause reproductive damage by the excessive production of reactive oxygen species (ROS), which exacerbates oxidative stress, inflammation, and endocrine disruption. Natural antioxidants, mainly polyphenols, carotenoids, and vitamins, have been shown to mitigate heavy metal-induced reproductive toxicity potentially. In this review, accumulated evidences on the influences of four non-essential heavy metals As, Cd, Pb, and Hg on both males and females reproductive system were established. The purpose of this review is to explore the potential mechanisms of the effects of heavy metals on reproductive function and point out the potential biomarkers of natural antioxidants interventions toward heavy metal-induced reproductive toxicity. Notably, increasing evidence proven that the regulations of hypothalamic-pituitary-gonadal axis, Nrf2, MAPK, or NF-κB pathways are the important mechanisms for the amelioration of heavy metal induced reproductive toxicity by natural antioxidants. It also provided a promising guidance for prevention and management of heavy metal-induced reproductive toxicity.

Quercetin Supplementation Alleviates Cadmium Induced Genotoxicity-Mediated Apoptosis in Caprine Testicular Cells

Being a common environmental pollutant, cadmium causes detrimental health effects, including testicular injury. Herein, we document the ameliorative potential of quercetin, a potent antioxidant, against cadmium-induced geno-cytotoxicity and steroidogenic toxicity in goat testicular tissue. Cadmium induced different comet types (Type 0 - Type 4), indicating the varying degree of DNA-damage in testicular cells. The quantitative analysis at 50 and 100 µM cadmium concentration revealed the DNA damage with per cent tail DNA as 75.78 ± 1.49 and 94.65 ± 0.95, respectively, in comparison to the control group (8.87 ± 0.48) post 8 h exposure duration. Cadmium caused a substantial decrease in the activity of key steroidogenic enzymes' (3β-HSD and 17β-HSD) along with reduction of testosterone level in testicular tissue. Furthermore, cadmium treatment induced various types of deformities in sperm, altered the Bax/Bcl-2 expression ratio in testicular tissue and thus suggesting the apoptosis-mediated death of testicular cells. Simultaneous quercetin supplementation, however, significantly (p < 0.05) averted the aforementioned cadmium-mediated damage in testicular tissue. Conclusively, the cadmium-induced DNA-damage and decrease in steroidogenic potential results in death of testicular cells via apoptosis, which was significantly counteracted by quercetin co-supplementation, and thus preventing the cadmium-mediated cytotoxicity of testicular cells.

Bioactive Compounds Protect Mammalian Reproductive Cells from Xenobiotics and Heat Stress-Induced Oxidative Distress via Nrf2 Signaling Activation: A Narrative Review

Oxidative stress occurs when there is an imbalance between the production of reactive oxygen species (ROS) and the body's antioxidant defenses. It poses a significant threat to the physiological function of reproductive cells. Factors such as xenobiotics and heat can worsen this stress, leading to cellular damage and apoptosis, ultimately decreasing reproductive efficiency. The nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway plays a crucial role in defending against oxidative stress and protecting reproductive cells via enhancing antioxidant responses. Dysregulation of Nrf2 signaling has been associated with infertility and suboptimal reproductive performance in mammals. Recent advancements in therapeutic interventions have underscored the critical role of Nrf2 in mitigating oxidative damage and restoring the functional integrity of reproductive cells. In this narrative review, we delineate the harmful effects of heat and xenobiotic-induced oxidative stress on reproductive cells and explain how Nrf2 signaling provides protection against these challenges. Recent studies have shown that activating the Nrf2 signaling pathway using various bioactive compounds can ameliorate heat stress and xenobiotic-induced oxidative distress and apoptosis in mammalian reproductive cells. By comprehensively analyzing the existing literature, we propose Nrf2 as a key therapeutic target for mitigating oxidative damage and apoptosis in reproductive cells caused by exposure to xenobiotic exposure and heat stress. Additionally, based on the synthesis of these findings, we discuss the potential of therapies focused on the Nrf2 signaling pathway to improve mammalian reproductive efficiency.

Molybdenum and cadmium co-induce apoptosis and ferroptosis through inhibiting Nrf2 signaling pathway in duck (Anas platyrhyncha) testes

Cadmium (Cd) and high molybdenum (Mo) are injurious to the body. Previous research has substantiated that Cd and Mo exposure caused testicular injury of ducks, but concrete mechanism is not fully clarified. To further survey the toxicity of co-exposure to Cd and Mo in testis, 40 healthy 8-day-old Shaoxing ducks (Anas platyrhyncha) were stochasticly distributed to 4 groups and raised with basic diet embracing Cd (4 mg/kg Cd) or Mo (100 mg/kg Mo) or both. At the 16th wk, testis tissues were gathered. The characteristic ultrastructural changes related to apoptosis and ferroptosis were observed in Mo or Cd or both groups. Besides, Mo or Cd or both repressed nuclear factor erythroid 2-related factor 2 (Nrf2) pathway via decreasing Nrf2, Heme oxygenase-1 (HO-1), NAD(P)H quinone oxidoreductase 1 (NQO1), Glutamate-cysteine ligase catalytic subunit (GCLC) and Glutamate-cysteine ligase modifier subunit (GCLM) mRNA expression of and Nrf2 protein expression, then stimulated apoptosis by elevating Bcl-2 antagonist/killer-1 (Bak-1), Bcl-2-associated X-protein (Bax), Cytochrome complex (Cyt-C), caspase-3 mRNA expression, cleaved-caspase-3 protein expression and apoptosis rate, as well as reducing B-cell lymphoma-2 (Bcl-2) mRNA expression and ratio of Bcl-2 to Bax, and triggered ferroptosis by upregulating Acyl-CoA Synthetase Long Chain Family Member 4 (ACSL4), transferrin receptor (TFR1) and Prostaglandin-Endoperoxide Synthase 2 (PTGS2) expression levels, and downregulating ferritin heavy chain 1 (FTH1), ferritin light chain 1 (FTL1), ferroportin 1 (FPN1), solute carrier family 7 member 11 (SCL7A11) and glutathione peroxidase 4 (GPX4) expression levels. The most obvious changes of these indexes were observed in co-treated group. Altogether, the results announced that Mo or Cd or both evoked apoptosis and ferroptosis by inhibiting Nrf2 pathway in the testis of ducks, and co-exposure to Mo and Cd exacerbated these variations.

Investigation of the protective effects of piceatannol on experimental subarachnoid hemorrhage in rats

BACKGROUND

Subarachnoid hemorrhage (SAH) is one of the most prevalent brain injuries in humans which has poor prognosis and high mortality rates. Due to several medical or surgical treatment methods, a gold standard method doesn't exist for SAH treatment. Piceatannol (PCN), a natural analog of resveratrol, was reported to reduce inflammation and apoptosis promising a wide range of therapeutic alternatives. In this study, we aimed to investigate the effects of PCN in an experimental SAH model. The alleviating effects of PCN in the hippocampus in an experimental SAH model were investigated for the first time.

METHODS AND RESULTS

In this study, 27 Wistar Albino male rats (200-300 g; 7-8 week) were used. Animals were divided into three groups; SHAM, SAH, and SAH + PCN. SAH model was created with 120 µl of autologous arterial tail blood to prechiasmatic cisterna. 30 mg/kg PCN was administered intraperitoneally at 1st h after SAH. Neurological evaluation was performed with Garcia's score. RT-PCR was performed for gene expression levels in the hippocampus. Pyknosis, edema, and apoptosis were evaluated by H&E and TUNEL staining. Our results indicated that PCN administration reduced apoptosis (P < 0.01), cellular edema, and pyknosis (P < 0.05) in the hippocampus after SAH. Moreover, PCN treatment significantly decreased the expression levels of TNF-α (P < 0.01), IL-6 (P < 0.05), NF-κB (P < 0.05), and Bax (P < 0.05) in the hippocampus.

CONCLUSIONS

Our results demonstrated that PCN might be a potential therapeutic adjuvant agent for the treatment of early brain injury (EBI) following SAH. Further studies are required to clarify the underlying mechanisms and treatment options of SAH.

E-Stilbenes: General Chemical and Biological Aspects, Potential Pharmacological Activity Based on the Nrf2 Pathway

Stilbenes are phytoalexins, and their biosynthesis can occur through a natural route (shikimate precursor) or an alternative route (in microorganism cultures). The latter is a metabolic engineering strategy to enhance production due to stilbenes recognized pharmacological and medicinal potential. It is believed that in the human body, these potential activities can be modulated by the regulation of the nuclear factor erythroid derived 2 (Nrf2), which increases the expression of antioxidant enzymes. Given this, our review aims to critically analyze evidence regarding E-stilbenes in human metabolism and the Nrf2 activation pathway, with an emphasis on inflammatory and oxidative stress aspects related to the pathophysiology of chronic and metabolic diseases. In this comprehensive literature review, it can be observed that despite the broad number of stilbenes, those most frequently explored in clinical trials and preclinical studies (in vitro and in vivo) were resveratrol, piceatannol, pterostilbene, polydatin, stilbestrol, and pinosylvin. In some cases, depending on the dose/concentration and chemical nature of the stilbene, it was possible to identify activation of the Nrf2 pathway. Furthermore, the use of some experimental models presented a challenge in comparing results. In view of the above, it can be suggested that E-stilbenes have a relationship with the Nrf2 pathway, whether directly or indirectly, through different biological pathways, and in different diseases or conditions that are mainly related to inflammation and oxidative stress.

Redox Homeostasis and Nrf2-Regulated Mechanisms Are Relevant to Male Infertility

Infertility represents a significant global health challenge, affecting more than 12% of couples worldwide, and most cases of infertility are caused by male factors. Several pathological pathways are implicated in male infertility. The main mechanisms involved are driven by the loss of reduction-oxidation (redox) homeostasis and the resulting oxidative damage as well as the chronic inflammatory process. Increased or severe oxidative stress leads to sperm plasma membrane and DNA oxidative damage, dysregulated RNA processing, and telomere destruction. The signaling pathways of these molecular events are also regulated by Nuclear factor-E2-related factor 2 (Nrf2). The causes of male infertility, the role of oxidative stress in male infertility and the Keap1-Nrf2 antioxidant pathway are reviewed. This review highlights the regulatory role of Nrf2 in the balance between oxidants and antioxidants as relevant mechanisms to male fertility. Nrf2 is involved in the regulation of spermatogenesis and sperm quality. Establishing a link between Nrf2 signaling pathways and the regulation of male fertility provides the basis for molecular modulation of inflammatory processes, reactive oxygen species generation, and the antioxidant molecular network, including the Nrf2-regulated antioxidant response, to improve male reproductive outcomes.

Sericin and melatonin mitigate diethylnitrosamine-instigated testicular impairment in mice: Implications of oxidative stress, spermatogenesis, steroidogenesis, and modulation of Nrf2/WT1/SF-1 signaling pathways

AIMS

This study aimed to investigate the therapeutic influence of combination therapy with sericin and melatonin on attenuating diethylnitrosamine (DEN)-instigated testicular dysfunction in mice and defining the molecular mechanisms involved in orchestrating redox signaling pathways and restoring spermatogenesis and steroidogenesis.

MATERIALS AND METHODS

Different groups of male Swiss albino mice were established and injected with respective drugs intraperitoneally. Semen analysis, hormonal assays, and oxidative stress biomarkers were evaluated. Additionally, melatonin and its receptors, WT1, SF-1, vimentin, Nrf2, and ANXA1 expressions were assessed. Histopathological and ultrastructural features of the testes were investigated by semithin, SEM, and TEM analyses.

KEY FINDINGS

Exposure to DEN exhibited pathophysiological consequences, including a remarkable increase in lipid peroxidation associated with substantial diminutions in SOD, CAT, GPx, GSH, GSH:GSSG, and GST. Furthermore, it disrupted spermatozoa integrity, testosterone, FSH, LH, melatonin, and its receptors (MT1 and MT2) levels, implying spermatogenesis dysfunction. By contrast, treatment with sericin and melatonin significantly restored these disturbances. Interestingly, the combination therapy of sericin and melatonin noticeably augmented the Nrf2, WT1, and SF-1 expressions compared to DEN-treated mice, deciphering the amelioration perceived in antioxidant defense and spermatogenesis inside cells. Furthermore, immunohistochemical detection of ANXA1 alongside histopathological and ultrastructural analyses revealed evident maintenance of testicular structures without discernible inflammation or anomalies in mice administered with sericin and melatonin compared to the DEN-treated group.

SIGNIFICANCE

Our findings highlighted that treatment with sericin and melatonin alleviated the testicular tissues in mice from oxidative stress and dysregulated spermatogenesis and steroidogenesis engendered by DEN.

Environmental and occupational exposure to cadmium associated with male reproductive health risk: a systematic review and meta-analysis based on epidemiological evidence

There is an abundance of epidemiological evidence and animal experiments concerning the correlation between cadmium exposure and adverse male reproductive health outcomes. However, the evidence remains inconclusive. We conducted a literature search from PubMed, Embase, and Web of Science over the past 3 decades. Pooled r and 95% confidence intervals (CIs) were derived from Cd levels of the type of biological materials and different outcome indicators to address the large heterogeneity of existing literature. Cd was negatively correlated with semen parameters (r = - 0.122, 95% CI - 0.151 to - 0.092) and positively correlated with sera sex hormones (r = 0.104, 95% CI 0.060 to 0.147). Among them, Cd in three different biological materials (blood, semen, and urine) was negatively correlated with semen parameters, while among sex hormones, only blood and urine were statistically positively correlated. In subgroup analysis, blood Cd was negatively correlated with semen density, sperm motility, sperm morphology, and sperm count. Semen Cd was negatively correlated with semen concentration. As for serum sex hormones, blood Cd had no statistical significance with three hormones, while semen Cd was negatively correlated with testosterone. In summary, cadmium exposure might be associated with the risk of a decline in sperm quality and abnormal levels of sex hormones.

Pan-cancer and single-cell analysis reveal the prognostic value and immune response of NQO1

Background: Overexpression of the NAD(P)H: Quinone Oxidoreductase 1 (NQOI) gene has been linked with tumor progression, aggressiveness, drug resistance, and poor patient prognosis. Most research has described the biological function of the NQO1 in certain types and limited samples, but a comprehensive understanding of the NQO1's function and clinical importance at the pan-cancer level is scarce. More research is needed to understand the role of NQO1 in tumor infiltration, and immune checkpoint inhibitors in various cancers are needed. Methods: The NQO1 expression data for 33 types of pan-cancer and their association with the prognosis, pathologic stage, gender, immune cell infiltration, the tumor mutation burden, microsatellite instability, immune checkpoints, enrichment pathways, and the half-maximal inhibitory concentration (IC50) were downloaded from public databases. Results: Our findings indicate that the NQO1 gene was significantly upregulated in most cancer types. The Cox regression analysis showed that overexpression of the NQO1 gene was related to poor OS in Glioma, uveal melanoma, head and neck squamous cell carcinoma, kidney renal papillary cell carcinoma, and adrenocortical carcinoma. NQO1 mRNA expression positively correlated with infiltrating immune cells and checkpoint molecule levels. The single-cell analysis revealed a potential relationship between the NQO1 mRNA expression levels and the infiltration of immune cells and stromal cells in bladder urothelial carcinoma, invasive breast carcinoma, and colorectal cancer. Conversely, a negative association was noted between various drugs (17-AAG, Lapatinib, Trametinib, PD-0325901) and the NQO1 mRNA expression levels. Conclusion: NQO1 expression was significantly associated with prognosis, immune infiltrates, and drug resistance in multiple cancer types. The inhibition of the NQO1-dependent signaling pathways may provide a promising strategy for developing new cancer-targeted therapies.

Effects of perfluorododecanoic acid on testicular function in mice

Perfluorodecanoic acid (PFDoA) is a widely distributed environmental pollutant that can affect the functions of many organs. However, systematic evaluations of the effects of PFDoA on testicular functions are lacking. The aim of this study was to investigate the effects of PFDoA on mouse testicular functions, including spermatogenesis, testosterone synthesis, and stem Leydig cells (SLCs) in the interstitial tissue of the testis. PFDoA (0, 2, 5, 10 mg/kg/d) was administered via gavage to 2-month-old mice for 4 weeks. Serum hormone levels and sperm quality were assayed. Furthermore, to investigate the mechanisms by which PFDoA affects testosterone synthesis and spermatogenesis in vivo, the expression of StAR and P450scc in testicular tissue was measured by immunofluorescence staining and quantitative real-time PCR. In addition, the levels of SLC markers, including nestin and CD51, were studied. PFDoA decreased the luteinizing hormone concentration and sperm quality. Although the difference was not statistically significant, mean testosterone levels showed a downward trend. The expression of StAR, P450scc, CD51, and nestin was also suppressed in the PFDoA-treated groups compared with the control group. Our study suggested that PFDoA exposure can decrease testosterone biosynthesis, and even reduce the number of SLCs. These results indicated that PFDoA suppressed the main functions of testis, and further researches are required to identify strategies for preventing or reducing the effect of PFDoA on testicular function.

Combined apocynin and carvedilol protect against cadmium-induced testicular damage via modulation of inflammatory response and redox-sensitive pathways

Testicular damage is considered a severe complication of cadmium (Cd) exposure which is associated with tissue oxidative stress damage, inflammation, and apoptosis. The present study investigated the antioxidant, anti-inflammatory, and anti-apoptotic activities of apocynin (APO) and carvedilol (CVD) against Cd-induced acute testicular damage. Rats were allocated into five groups as follows: normal control (received vehicle), Cd control group (2 mg/kg, i.p), APO-treated group (25 mg/kg, P.O.), CVD-treated group (10 mg/kg, P.O.), and combination group (APO + CVD). Blood, serum, and tissue samples were withdrawn for hematological, biochemical, molecular, and histological analyses. The present results confirmed testicular damage after cd exposure as indicated by alteration of serum hormonal levels, hematological defects, histopathological changes, and loss of steroidogenic functions. Besides, Cd injection-induced up-regulation of NADPH oxidase, MDA, NF-κB, IRF3, MPO, pro-inflammatory cytokines, Bax, and cleaved caspase-3 expression concomitant with down-regulation of Nrf2, GSH, SOD, and Bcl2 expression. Interestingly, pretreatment with APO and/or CVD significantly relieved Cd-induced testicular damage at cellular and molecular levels. Notably, the combined protective effect of APO plus CVD was higher than the protective effect of each drug alone. Overall, combined APO and CVD could serve as a good candidate for protection against Cd-induced testicular damage via suppression of inflammatory response and modulation of the redox-sensitive pathway.

Exploring Nrf2 as a therapeutic target in testicular dysfunction

Testicular dysfunction, a major contributory factor to infertility, has received a lot of attention over the recent years. Several studies have linked abnormal sperm function and morphology with an enhanced generation of reactive oxygen species (ROS) and oxidative stress. The nuclear factor erythroid-derived 2 (Nrf2) is a transcriptional response to cellular stresses (intrinsic or extrinsic) that regulates the oxidative status, mitochondrial dysfunction, inflammation, and proteostasis. In this review, the therapeutic role of Nrf2 was explored. To do so, scientific data were retrieved from databases such as Elsevier, Wiley, Web of Science, Springer, PubMed, Taylor and Francis, and Google Scholar using search terms such as "Nrf2" and "testis," "sperm," "testicular function," and "testosterone." It has been noted that Nrf2 influences the physiology and pathology of testicular dysfunction, especially in the spermatogenic process, by regulating cellular resistance to oxidative stress, inflammation, and environmental toxicants. However, numerous compounds serve as activators and inhibitors of testicular Nrf2. Nrf2 activators might play a therapeutic role in the prevention and treatment of testicular dysfunction, while molecules that inhibit Nrf2 might induce dysfunction in testis components. Nrf2 activators protect cells against oxidative damage and activate Nrf2/KEAP1 signaling which promotes its movement to the nucleus, and increased Nrf2 function and expression, along with their downstream antioxidant gene. Nrf2 inhibitors facilitate oxidative stress via interfering with the Nrf2 signal pathway. The Nrf2 activation could serve as a promising therapeutic target for testicular dysfunction. This review explored the effect of Nrf2 on testicular function while highlighting potential activators and inhibitors of Nrf2.

Costus speciosus extract protects against the oxidative damage of zearalenone via modulation of inflammatory cytokines, Nrf2 and iNOS gene expression in rats

Zearalenone (ZEN) is a non-steroidal estrogenic mycotoxin that induces severe health disturbances in humans and animals. This study aimed to determine the bioactive compounds in Costus speciosus extract (CSE) using GC-MS and evaluate its protective capability against ZEN-induced oxidative damage, genotoxicity, and cytotoxicity in rats. Six groups of male Sprague Dawley rats were treated orally for 15 days including the control group, CSE-treated groups at low (200 mg/kg b. w) or high (400 mg/kg b. w) dose, ZEN-treated group (40 μg/kg b. w), and the groups treated with ZEN plus the low or the high dose of CSE. Blood and tissue samples were collected for different assays and pathological analyses. The results of GC-MS indicated the identification of 6 compounds and Azulene was the major. Animals that received ZEN showed severe disturbances in serum biochemical, cytokines, oxidative stress indicators, mRNA expression of iNOS, Nrf2, and inflammatory-related genes. ZEN also increased micronucleated polychromatic erythrocytes (MNPCEs) and comet tail formation in bone marrow cells along with the disturbances in the histological architecture of the liver and kidney. Co-administration of CSE plus ZEN could normalize the majority of the tested parameters and the histological picture at a dose as low as 200 mg/kg b. w. Therefore, CSE protects against ZEN toxicity via its antioxidant activity, modulation of iNOS, inflammatory-related genes, and the Nrf2 pathway and it could be used in the endemic regions.

Impacts of cadmium on male fertility: Lessons learnt so far

Cadmium (Cd) is one of the most dangerous heavy metals in the world. Globally, toxicities associated with cadmium and its attendant negative impact on humans and animals cannot be under-estimated. Cd is a heavy metal, and people are exposed to it through contaminated foods and smoking. Cd exerts its deleterious impacts on the testes (male reproductive system) by inducing oxidative stress, spermatogenic cells apoptosis, testicular inflammation, decreasing androgenic and sperm cell functions, disrupting ionic homeostasis, pathways and epigenetic gene regulation, damaging vascular endothelium and blood testes barrier. In association with other industrial by-products, Cd has been incriminated for the recent decline of male fertility rate seen in both man and animals. Understanding the processes involved in Cd-induced testicular toxicity is vital for the innovation of techniques that will help ameliorate infertility in males. In this review, we summed up recent studies on the processes of testicular toxicity and male infertility due to Cd exposure. Also, the usage of different compounds including phytochemicals, and plant extracts to manage Cd reprotoxicity will be reviewed.

Activated Nrf-2 Pathway by Vitamin E to Attenuate Testicular Injuries of Rats with Sub-chronic Cadmium Exposure

Cadmium (Cd), a heavy metal element, cumulates in the testis and can cause male reproductive toxicity. Although vitamin E (VE) as one of potential antioxidants protects the testis against toxicity of Cd, the underlying mechanism remained uncompleted clear. The aim of this study was to investigate whether the Nrf-2 pathway is involved with the protective effect of VE on testicular damages caused by sub-chronic Cd exposure. Thirty-two SD rats were divided into four groups and orally administrated with VE and/or Cd for 28 consecutive days: control group, VE group (100 mg VE/kg), Cd group (5 mg CdCl₂/kg), and VE + Cd group (100 mg VE/kg + 5 mg CdCl₂/kg). The results showed that 28-day exposure of Cd caused accumulation of Cd, histopathological lesions, and alternations of sperm parameters (elevated rate of abnormal sperm, decreased count of sperm, declined motility, and viability of sperm). Moreover, the rats exposed to Cd showed significant oxidative stress (increased contents of MDA and decreased levels or activities of T-AOC, GSH, CAT, SOD and GSH-Px) and inhibition of Nrf-2 signaling pathway (downregulation of Nrf-2, HO-1, NQO-1, GCLC, GCLM and GST) of the testes. In contrast, VE treatment significantly reduced the Cd accumulation, alleviated histopathological lesions and dysfunctions, activated Nrf-2 pathway, and attenuated the oxidative stress caused by Cd in the testes of rats. In conclusion, VE, through upregulating Nrf-2 pathway, could protect testis against oxidative damages induced by sub-chronic Cd exposure.

Differential Expression Profiles and Potential Intergenerational Functions of tRNA-Derived Small RNAs in Mice After Cadmium Exposure

Cadmium (Cd) is a toxic heavy metal and ubiquitous environmental endocrine disruptor. Previous studies on Cd-induced damage to male fertility mainly focus on the structure and function of testis, including cytoskeleton, blood-testis barrier, and steroidogenesis. Nevertheless, to date, no studies have investigated the effects of Cd exposure on sperm epigenetic inheritance and intergenerational inheritance. In our study, we systematically revealed the changes in sperm tRNA-derived small RNAs (tsRNA) profiles and found that 14 tsRNAs (9 up-regulated and 5 down-regulated) were significantly altered after Cd exposure. Bioinformatics of tsRNA-mRNA-pathway interactions revealed that the altered biological functions mainly were related to ion transmembrane transport, lipid metabolism and cell membrane system. In addition, we focused on two stages of early embryo development and selected two organs to study the impact of these changes on cell membrane system, especially mitochondrion and lysosome, two typical membrane-enclosed organelles. Surprisingly, we found that the content of mitochondrion was significantly decreased in 2-cell stage, whereas remarkably increased in the morula stage. The contents of mitochondrion and lysosome were increased in the testes of 6-day-old offspring and livers of adult offspring, whereas remarkably decreased in the testes of adult offspring. This provides a possible basis to further explore the effects of paternal Cd exposure on offspring health.

LXA4 protects against blue-light induced retinal degeneration in human A2E-laden RPE cells and Balb-c mice

Background

Age-related macular degeneration (AMD) is one of the leading causes of permanent visual impairment in the elderly. Blue light (BL) has been reported to cause retinal damage and contribute to the onset and development of severe AMD. N-retinylidene-N-retinylethanolamine (A2E), a lipofuscin fluorophore, accumulates with ageing in the retinal pigment epithelium (RPE) cells. Once exposed to BL, A2E easily oxidizes to A2E-epoxides, causing oxidative-stress injury to the retina. Lipoxin A4 (LXA4), an endogenous anti-antioxidant lipid, plays a key role in multiple organs by binding to the formyl-peptide receptor-like 1 (FPRL1). This study examined the protective effects of LXA4 on oxidative-stress injury induced by BL exposure, and clarified the underlying mechanisms in cultured RPE cells and Balb-c mice.

Methods

LXA4 diluent was orally administered to mice before retinal degeneration was established. Optical coherence tomography, retinal histology, and RPE cell injury were assessed.

Results

LXA4 administration significantly ameliorated retinal damage as evidenced by the thicknesses of the retinal layers and the tight junctions of RPE cells in vivo. LXA4 inhibited BL-induced reactive oxygen species (ROS) production, reduced tight junctions, and the death of A2E-laden RPE cells. LXA4 also potently increased the expression of haem oxygenase-1 (HO1) and NAD(P)H quinone oxidoreductase 1 (NQO1), probably by decreasing the association between nuclear factor erythroid 2-related factor 2 (NRF2) and Kelch-like ECH (Epichlorohydrin) -associated protein 1 (Keap1), and ameliorating NRF2 nuclear translocation and the antioxidant response element (ARE) deoxyribonucleic acid (DNA) binding activity.

Conclusions

Our results showed that LXA4 ameliorated retinal degeneration, and should be considered in the prevention and treatment of AMD.

Vitamin D3 protects against lead-induced testicular toxicity by modulating Nrf2 and NF-κB genes expression in rat

Lead (Pb) is an environmental toxin that has the ability to alter biological processes by inducing oxidative stress (OS) and inflammation. Nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor-kappa B (NF-κB) are two transcriptional factors that participate in the regulation of cellular responses against OS and inflammation. This study was conducted to evaluate the effects of vitamin D3 (VD) on the prevention of testicular damages of Pb and its association with Nrf2 and NF-κB gene expression levels and their downstream molecules. Forty male Wistar rats were divided into four groups and treatments were performed as following for four weeks: control group received no treatment, VD group were injected intramuscularly with 1000 IU of VD/Kg every other day, Pb group received 1000 mg of Pb/L of drinking water, and Pb + VD group were exposed to Pb and VD simultaneously. The results demonstrated significant decrease in the levels of tissue antioxidants, and increase in inflammatory cytokines in the Pb-intoxicated group, with increased Nrf2 and NF-κB mRNA levels. A remarkable reduction in sperm criteria and a significant disruption in serum hormones were also observed. Anyhow, VD supplementation during exposure to Pb showed a significant protective effect against all pathophysiologic alterations caused by Pb. Furthermore, VD affected the expression of Nrf2 and NF-κB and mitigated the harsh effects of Pb. In conclusion, our findings indicate that VD attenuated the toxic impacts of Pb on testis through modulation of Nrf2 and NF-κB gene expression levels which further regulated the OS and inflammatory responses.

Toxicological Evaluation of Piceatannol, Pterostilbene, and ε-Viniferin for Their Potential Use in the Food Industry: A Review

The application of stilbenes in the food industry is being considered because of their biological activities. Piceatannol, pterostilbene and ε-viniferin have awakened the industry’s interest. However, before they can be commercialized, we must first guarantee their safety for consumers. The present work reviews the toxicological studies performed with these stilbenes. A wide variety of studies has demonstrated their cytotoxic effects in both cancer and non-cancerous cell lines. In contrast, although DNA damage was detected by some authors, in vitro genotoxic studies on the effects of piceatannol, pterostilbene, and ε-viniferin remain scarce. None of the three reviewed substances have been evaluated using the in vitro tests required by the European Food Safety Authority (EFSA) as the first step in genotoxicity testing. We did not find any study on the toxic effects of these stilbenes in vivo. Thus, more studies are needed to confirm their safe use before they can be authorized as additive in the food industry.

Changes and relationship of N6-methyladenosine modification and long non-coding RNAs in oxidative damage induced by cadmium in pancreatic β-cells

N⁶-methyladenosine (m⁶A) modification and m⁶A-modified Long non-coding RNAs (LncRNAs) play crucial roles in various pathological processes, yet their changes and relationship in cadmium-induced oxidative damage are largely unknown. Here, five m⁶A-modified LncRNAs (LncRNA-TUG1, LncRNA-PVT1, LncRNA-MALAT1, LncRNA-XIST, LncRNA-NEAT1), which have been evidenced to involve in oxidative damage, were selected and their binding proteins were submitted to bioinformatics analysis. Our analysis results showed that these five m⁶A-modified LncRNAs bound to different regulatory proteins of m⁶A modification, implicating that m⁶A modification on LncRNAs may synergistically control by multiple regulatory proteins. Furthermore, the detection data revealed that levels of m⁶A modification, methyltransferase-like 3 (METTL3) and fat mass and obesity-associated protein (FTO) were all significantly decreased in CdSO₄-induced oxidative damage, which was demonstrated by increasing ROS accumulation and MDA contents as well as decreasing SOD activities. More importantly, LncRNA-MALAT1 and LncRNA-PVT1 indicated downward trend and showed positive relationship with m⁶A modification. Collectively, our results showed that m⁶A modification and m⁶A-modified LncRNAs may involve in oxidative damage induced by cadmium.

Piceatannol promotes hepatic and renal AMPK/SIRT1/PGC-1α mitochondrial pathway in rats exposed to reserpine or gamma-radiation

Human exposure to radio-therapeutic doses of gamma rays can produce late effects, which negatively affect cancer patients' quality of life, work prospects, and general health. This study was performed to explore the role of Piceatannol (PIC) in the process of "mitochondrial biogenesis" signaling pathway as possible management of disturbances induced in stressed animal model(s) either by gamma-irradiation (IR) or administration of reserpine (RES); as a mitochondrial complex-I inhibitor. PIC (10 mg/kg BW/day; orally) were given to rats for 7 days, after exposure to an acute dose of γ-radiation (6 Gy), or after a single reserpine injection (1 g/kg BW; sc). Compared to reserpine or γ-radiation, PIC has attenuated hepatic and renal mitochondrial oxidative stress denoted by the significant reduction in the content of lipid peroxides and NO with significant induction of SOD, CAT, GSH-PX, and GR activities. PIC has also significantly alleviated the increase of the inflammatory markers, TNF-α and IL-6 and apoptotic markers, cytochrome c, and caspase-3. The decrease of oxidative stress, inflammation, and apoptotic responses were linked to a significant amelioration in mitochondrial biogenesis demonstrated by the increased expression and proteins' tissue contents of SIRT1/p38-AMPK, PGC-1α signaling pathway. The results are substantiated by the significant amelioration in mitochondrial function verified by the higher levels of ATP content, and complex I activity, besides the improvement of hepatic and renal functions. Additionally, histopathological examinations of hepatic and renal tissues showed that PIC has modulated tissue architecture after reserpine or gamma-radiation-induced tissue damage. Piceatannol improves mitochondrial functions by regulating the oxidant/antioxidant disequilibrium, the inflammatory and apoptotic responses, suggesting its possible use as adjuvant therapy in radio-therapeutic protocols to attenuate hepatic and renal injuries.

Comprehensive Review of Cadmium Toxicity Mechanisms in Male Reproduction and Therapeutic Strategies

Cadmium (Cd) has been widely studied as an environmental pollutant for many years. Numerous studies have reported that Cd exposure causes damage to the heart, liver, kidneys, and thyroid in vivo. The emerging evidence suggests that Cd exposure induces damage on male reproductive system, which is related to oxidative stress, inflammation, steroidogenesis disruption, and epigenetics. Current preclinical animal studies have confirmed a large number of proteins and intracellular signaling pathways involved in the pathological process of Cd-induced male reproductive damage and potential measures for prophylaxis and treatment, which primarily include antioxidants, anti-inflammatory agents, and essential ion supplement. However, explicit pathogenesis and effective treatments remain uncertain. This review collects data from the literatures, discusses the underlying mechanisms of Cd-induced toxicity on male reproductive function, and summarizes evidence that may provide guidance for the treatment and prevention of Cd-induced male reproductive toxicity.

Ferulic acid influences Nrf2 activation to restore testicular tissue from cadmium-induced oxidative challenge, inflammation, and apoptosis in rats

Here, we examined the protective effect of ferulic acid (FA) on cadmium chloride (CdCl₂ )-mediated reproductive toxicity in male rats. Animals were divided into four groups: control, FA (20 mg/kg), CdCl₂ (6.5 mg/kg), and FA + CdCl₂ . CdCl₂ treatment evoked a significant increase in testis cadmium concentration in addition to obvious increase in testosterone, luteinizing hormone, and follicle-stimulating hormone levels. Moreover, CdCl₂ -induced oxidative damage through exhausting the cellular defenses (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione) and downregulating the nuclear factor erythroid 2-related factor 2 (Nrf2) expression accompanied by increases of malondialdehyde and nitric oxide contents. Testicular inflammation was evident indicated by increased levels of interleukin-1β and tumor necrosis factor-α in CdCl₂ -treated rats. CdCl₂ exposure also decreased the expression of the proliferating cell nuclear antigen and augmented apoptotic events associated with prominent histopathological alterations. However, FA coadministration mitigated the impaired hormonal level, apoptotic and inflammatory injuries elicited by CdCl_2, and maintained the oxidant/antioxidant balance in testicular tissue via Nrf2 activation. PRACTICAL APPLICATIONS: Cadmium is an environmental toxicant and known to cause adverse effects including reproductive toxicity. However, antioxidant application has been found to protect against heavy metals-mediated toxic effects. Here, we examined the potential protective efficacy of ferulic acid against cadmium-mediated testicular impairments through estimating the amount of cadmium in the testis, hormonal profile, oxidative status, inflammatory response, apoptotic and proliferating markers in addition to the histopathological alterations. The obtained findings revealed that ferulic acid supplementation was able to abolish the testicular damages coupled with cadmium exposure. The protective efficiency of ferulic acid may correlated with its strong antioxidant, anti-inflammatory, and antiapoptotic activities; suggesting that ferulic acid may be used to ameliorate cadmium-induced testicular deficits.

Back to Nucleus: Combating with Cadmium Toxicity Using Nrf2 Signaling Pathway as a Promising Therapeutic Target

There are concerns about the spread of heavy metals in the environment, and human activities are one of the most important factors in their spread. These agents have the high half-life resulting in their persistence in the environment. So, prevention of their spread is the first step. However, heavy metals are an inevitable part of modern and industrial life and they are applied in different fields. Cadmium is one of the heavy metals which has high carcinogenesis ability. Industrial waste, vehicle emissions, paints, and fertilizers are ways of exposing human to cadmium. This potentially toxic agent harmfully affects the various organs and systems of body such as the liver, kidney, brain, and cardiovascular system. Oxidative stress is one of the most important pathways of cadmium toxicity. So, improving the antioxidant defense system can be considered as a potential target. On the other hand, the Nrf2 signaling pathway involves improving the antioxidant capacity by promoting the activity of antioxidant enzymes such as catalase and superoxide dismutase. At the present review, we demonstrate how Nrf2 signaling pathway can be modulated to diminish the cadmium toxicity.

Nrf2 mitigates prolonged PM2.5 exposure-triggered liver inflammation by positively regulating SIKE activity: Protection by Juglanin

Air pollution containing particulate matter (PM) less than 2.5 μm (PM2.5) plays an essential role in regulating hepatic disease. However, its molecular mechanism is not yet clear, lacking effective therapeutic strategies. In this study, we attempted to investigate the effects and mechanisms of PM2.5 exposure on hepatic injury by the in vitro and in vivo experiments. At first, we found that PM2.5 incubation led to a significant reduction of nuclear factor erythroid-derived 2-related factor 2 (Nrf2), along with markedly reduced expression of different anti-oxidants. Notably, suppressor of IKKε (SIKE), known as a negative regulator of the interferon pathway, was decreased in PM2.5-incubated cells, accompanied with increased activation of TANK-binding kinase 1 (TBK1) and nuclear factor-κB (NF-κB). The in vitro studies showed that Nrf2 positively regulated SIKE expression under the conditions with or without PM2.5. After PM2.5 treatment, Nrf2 knockdown further accelerated SIEK decrease and TBK1/NF-κB activation, and opposite results were observed in cells with Nrf2 over-expression. Subsequently, the gene loss- and gain-function analysis demonstrated that SIKE deficiency further aggravated inflammation and TBK1/NF-κB activation caused by PM2.5, which could be abrogated by SIKE over-expression. Importantly, SIKE-alleviated inflammation was mainly dependent on TBK1 activation. The in vivo studies confirmed that SIKE- and Nrf2-knockout mice showed significantly accelerated hepatic injury after long-term PM2.5 exposure through reducing inflammatory response and oxidative stress. Juglanin (Jug), mainly isolated from Polygonum aviculare, exhibits anti-inflammatory and anti-oxidant effects. We found that Jug could increase Nrf2 activation, and then up-regulated SIKE in cells and liver tissues, mitigating PM2.5-induced liver injury. Together, all these data demonstrated that Nrf2 might positively meditate SIKE to inhibit inflammatory and oxidative damage, ameliorating PM2.5-induced liver injury. Jug could be considered as an effective therapeutic strategy against this disease by improving Nrf2/SIKE signaling pathway.