The Nrf2 cell defence pathway: Keap1-dependent and -independent mechanisms of regulation

The tumor/normal tissue ratio of Keap1 protein is a predictor for lymphovascular invasion in colorectal cancer: A correlation study between the Nrf2 and KRas pathways

PURPOSE: Oxidative stress has impacts on the KRas and Nrf2/Keap1 pathways, which have multiple interactions with each other and play important roles in colorectal cancer (CRC). This study investigated the expressions of proteins in the KRas and Nrf2/Keap1 pathways and their associations with clinicopathological features in CRC.METHODS: The protein levels of Nrf2, Keap1, Bach1, p62, HO1, KRas, Erk, Raf1 and PI3K in both the tumor and normal tissues of 60 CRC subjects were determined by Western blot and their T/N (tumor/normal tissue) ratios were correlated with clinicopathological features.RESULTS: The T/N ratios of proteins in the KRas and Nrf2/Keap1 pathways had correlation patterns and proximity profiles in cluster dendrograms different in CRC with different status of lymphovascular invasion (LVI) or lymph node/distant metastases. The Keap1 protein T/N ratio was a significant predictor (odd ratio: 2.24; 95% confidence interval: 1.26 - 4.38) of LVI, which in turn predicted metastases (11.0; 3.49 - 39.8).CONCLUSION: The interactions between the KRas and Nrf2/Keap1 pathways may be affected differently by LVI and metastases, and the protein T/N ratio of Keap1 may be helpful for predicting LVI in CRC.

7-O-Methylluteolin Suppresses the 2,4-Dinitrochlorobenzene-Induced Nrf2/HO-1 Pathway and Atopic Dermatitis-like Lesions

7-O-methylluteolin (7-ML) is a flavonoid isolated from the aerial parts of Wikstroemia ganpi (W. ganpi). We describe the anti–atopic dermatitis (AD) effects of 7-ML in tert-butyl hydroperoxide (tBHP)-induced HepG2 cells and 2,4-dinitrochlorobenzene (DNCB)-induced SKH-1 hairless mice. Results demonstrated that 7-ML dose-dependently inhibited the activation of Nrf2 (nuclear factor-erythroid 2-related factor 2) in tBHP-induced HepG2 cells. 7-ML applied topically to our DNCB-induced mouse model upregulated the antioxidant protein expression (phosphorylated Nrf2 (pNrf2), Nrf2, and heme oxygenase-1 (HO-1)) in skin tissues, improved epidermal thickness, and reduced mast cell infiltration into the skin. In addition, 7-ML reduced the serum levels of immunoglobulin E (IgE) and interleukin-4 (IL-4) and improved skin barrier functions. These results suggest that 7-ML should be considered a novel antioxidant and anti-AD agent.

Nrf2 driven macrophage responses in diverse pathophysiological contexts: Disparate pieces from a shared molecular puzzle

The wide anatomical distribution of macrophages and their vast array of functions match various polarization states and their involvement in homeostasis and disease. The confluence of different cellular signaling networks, including direct involvement in inflammation, at the doorstep of the transcription factor Nuclear Factor- erythroid (NF-E2) p45-related factor 2 (Nrf2) activation raises the importance of deciphering the molecular circuitry at the background of multiple-discrete and antagonistic yet flexible and contextual pathways. While we primarily focus on wound healing and repair mechanisms that are affected in diabetic foot ulcers (DFUs), we strive to explore the striking similarities and differences in molecular events including inflammation, angiogenesis, and fibrosis during tissue injury and wound persistence that accumulates pro-inflammatory senescent macrophages, as a means to identify possible targets or cellular mediators to lessen DFU disease burden. In addition, the role of iron in the modulation of Nrf2 response in macrophages is crucial and reviewed here. Targeted approaches, unlike conventional treatments, in DFU management will require the review and re-assessment of mediators with relevance to other pathological conditions.

Targeting Nrf2 in ischemia-reperfusion alleviation: From signaling networks to therapeutic targeting

The nuclear factor erythroid 2-related factor 2 (Nrf2) is a master regulator of redox balance and it responds to various cell stresses that oxidative stress is the most well-known one. The Nrf2 should undergo nuclear translocation to exert its protective impacts and decrease ROS production. On the other hand, ischemic/reperfusion (I/R) injury is a pathological event resulting from low blood flow to an organ and followed by reperfusion. The I/R induces cell injury and organ dysfunction. The present review focuses on Nrf2 function in alleviation of I/R injury. Stimulating of Nrf2 signaling ameliorates I/R injury in various organs including lung, liver, brain, testis and heart. The Nrf2 enhances activity of antioxidant enzymes to reduce ROS production and prevent oxidative stress-mediated cell death. Besides, Nrf2 reduces inflammation via decreasing levels of pro-inflammatory factors including IL-6, IL-1β and TNF-α. Nrf2 signaling is beneficial in preventing apoptosis and increasing cell viability. Nrf2 induces autophagy to prevent apoptosis during I/R injury. Furthermore, it can interact with other molecular pathways including PI3K/Akt, NF-κB, miRNAs, lncRNAs and GSK-3β among others, to ameliorate I/R injury. The therapeutic agents, most of them are phytochemicals such as resveratrol, berberine and curcumin, induce Nrf2 signaling in I/R injury alleviation.

Ayurvedic Herbal Therapies: A Review of Treatment and Management of Dementia

Dementia has been characterized by atypical neurological syndromes and several cognitive deficits, such as extended memory loss, strange behavior, unusual thinking, impaired judgment, impotence, and difficulty with daily living activities. Dementia is not a disease, but it is caused by several neurodegenerative diseases, such as Alzheimer's, Parkinson's, and Lewy's bodies. Several drugs and remedies are indicated for alleviating unusual cognitive decline, but no effective pharmacological treatment regimens are available without side effects. Herbal drugs or traditional medicines like Ayurveda have been known for facilitating and corroborating the balance between mind, brain, body, and environment. Ayurvedic therapy comprises 600 herbal formulas, 250 single plant remedies, and natural and holistic health-giving treatments that relieve dementia in patients and increase vitality. Ayurvedic Rasayana herbs [rejuvenating elements] strengthen the brain cells, enhance memory, and decrease stress. The current medicine scenario in the treatment of dementia has prompted the shift in exploring the efficacy of ayurvedic medicine, its safety, and its efficiency. This review presents the literature on several herbal treatments for improving dementia symptomatology and patients' quality of life.

Kynurenine monooxygenase inhibition and associated reduced quinolinic acid reverses depression-like behaviour by upregulating Nrf2/ARE pathway in mouse model of depression: In-vivo and In-silico studies

Kynurenine pathway, a neuroimmunological pathway plays a substantial role in depression. Consistently, increased levels of neurotoxic metabolite of kynurenine pathway; quinolinic acid (QA) found in the suicidal patients and remitted major depressive patients. QA, an endogenous modulator of N-methyl-d-aspartate receptor is produced by microglial cells, may serve as a potential candidate for a link between antioxidant defence system and immune changes in depression. Further, nuclear factor (erythroid-derived 2) like 2 (Nrf2), an endogenous antioxidant transcription factor plays a significant role in maintaining antioxidant homeostasis during basal and stress conditions. The present study was designed to explore the effects of KMO-inhibition (Kynurenine monooxygenase) and association of reduced QA on Keap1/Nrf2/ARE pathway activity in olfactory bulbectomized mice (OBX-mice). KMO catalysis the neurotoxic branch of kynurenine pathway directing the synthesis of QA. KMO inhibitionshowed significant reversal of depressive-like behaviour, restored Keap-1 and Nrf2 mRNA expression, and associated antioxidant levels in cortex and hippocampus of OBX-mice. KMO inhibition also increased PI3K/AKT mRNA expression in OBX-mice. KMO inhibition and associated reduced QA significantly decreased inflammatory markers, kynurenine and increased the 5-HT, 5-HIAA and tryptophan levels in OBX-mice. Furthermore, molecular docking studies has shown good binding affinity of QA towards ubiquitin proteasome complex and PI3K protein involved in Keap-1 dependent and independent proteasome degradation of Nrf2 respectively supporting our in-vivo findings. Hence, QA might act as pro-oxidant through downregulating Nrf2/ARE pathway along with modulating other pathways and KMO inhibition could be a potential therapeutic target for depression treatment.

AF8c, a Multi-Kinase Inhibitor Induces Apoptosis by Activating DR5/Nrf2 via ROS in Colorectal Cancer Cells

Simple Summary

AF8c, a lapatinib hybrid quinazoline-based EGFR/HER2 inhibitor, was chosen to scrutinize its antiproliferative activity in colorectal cancer (CRC) cells. We found that AF8cinduced apoptosis in CRC cells via diverse mechanisms. In addition to inhibiting the phosphorylation of the ErbB family, AF8c increased the mRNA and protein levels of death receptor 5 (DR5) in vitro and in vivo. In addition, AF8c upregulated several ER stress proteins and the redox-sensitive nuclear respiratory factor 2 alpha subunit (Nrf2) in a p53-dependent manner. We also found that the AF8c-induced increase in the levels of Nrf2, DR5, and apoptosis was diminished by p53 downregulation or knockdown. Furthermore, AF8c showed higher antiproliferative activity than lapatinib in the CRC mouse model in vivo. Therefore, our results suggest AF8c as a highly effective polypharmacological small molecule with an encouraging safety profile, both in vitro and in vivo, for further evaluation as a treatment of CRC.

Abstract

Our team has previously reported a series of quinazoline-based lapatinib hybrids as potent kinase-targeting anticancer agents. Among them, AF8c showed a relatively safe profile in colorectal cancer (CRC) cells. In this study, we delineate a novel anticancer activity of AF8c in CRC cells. AF8c mediated p53-dependent apoptosis of CRC cells via the generation of endoplasmic reticulum (ER) stress and reactive oxygen species (ROS), as well as activation of nuclear respiratory factor 2 alpha subunit (Nrf2) and death receptor 5 (DR5), among others. The silencing of DR5 attenuated the expression levels of Nrf2 and partially inhibited AF8c-induced apoptosis. Additionally, upregulation of Nrf2 by AF8c evoked apoptosis through a decrease in antioxidant levels. Treatment of a CRC mice model with AF8c also resulted in the upregulation of DR5, Nrf2, and CHOP proteins, subsequently leading to a significant decrease in tumor burden. In comparison with lapatinib, AF8c showed higher cellular antiproliferative activity at the tested concentrations in CRC cells and synergized TRAIL effects in CRC cells. Overall, our results suggest that AF8c-induced apoptosis may be associated with DR5/Nrf2 activation through ER stress and ROS generation in CRC cells. These findings indicate that AF8c represents a promising polypharmacological molecule for the treatment of human CRC.

Roles of NRF2 in Fibrotic Diseases: From Mechanisms to Therapeutic Approaches

Fibrosis is a persistent inflammatory response that causes scarring and tissue sclerosis by stimulating myofibroblasts to create significant quantities of extracellular matrix protein deposits in the tissue. Oxidative stress has also been linked to the development of fibrosis in several studies. The nuclear erythroid 2-related factor 2 (NRF2) transcription factor controls the expression of several detoxification and antioxidant genes. By binding to antioxidant response elements, NRF2 is activated by oxidative or electrophilic stress and promotes its target genes, resulting in a protective effect on cells. NRF2 is essential for cell survival under oxidative stress conditions. This review describes Kelch-like epichlorohydrin-associated protein 1 (KEAP1)/NRF2 signaling mechanisms and presents recent research advances regarding NRF2 and its involvement in primary fibrotic lesions such as pulmonary fibrosis, hepatic fibrosis, myocardial fibrosis, and renal fibrosis. The related antioxidant substances and drugs are described, along with the mechanisms by which KEAP1/NRF2 regulation positively affects the therapeutic response. Finally, the therapeutic prospects and potential value of NRF2 in fibrosis are summarized. Further studies on NRF2 may provide novel therapeutic approaches for fibrosis.

Moringa oleifera mitigates ethanol-induced oxidative stress, fatty degeneration and hepatic steatosis by promoting Nrf2 in mice

BACKGROUND

Moringa oleifera (M. oleifera) is cultivated throughout the world and it is known by numerous regional names and is consumed as medication for various diseases such as hypertension, diabetes, HIV and is potential source of nutrients and natural antioxidants making it among the most useful trees.

METHODS

We evaluated the therapeutic potential of M. oleifera on ethanol-induced fatty liver. The mice were treated with 30% ethanol (EtOH) alone or in combination with different concentration of M. oleifera extracts (100, 200 and 400 mg/kg). We performed biochemical estimation for the serum of important liver damage markers such as aspartate aminotransferase (AST), alanine aminotransferase (ALT) and triglyceride (TG). We performed histopathological analysis from the liver tissues of different mice groups. We also performed ELISA assay, western blotting analysis and SPECT imaging to obtain our results.

RESULTS

The results for serum (AST, p < 0.0001), (ALT, p < 0.0006) and triglyceride (TG, p < 0.0003) were found to be significantly reduced in all doses of M. oleifera extract treatment groups in comparison with the ethanol group. H&E staining analysis and scoring revealed a significant reduction in lipid droplet accumulation and a significant reduction of liver steatosis (p < 0.0001), lobular inflammation (p < 0.0013), ballooning (p < 0.0004) and immunohistochemistry for TNF-α. M. oleifera also ameliorated ethanol-induced oxidative stress evaluated through MDA (p < 0.0001), H₂DCFDA, JC-1 staining and a significant down-regulation of CYP2E1 enzyme (p < 0.0001) in the 200 and 400 mg/kg groups in comparison with EtOH groups. M. oleifera extract also boosted the antioxidant response evaluated through total GSH assay (p < 0.0001) and nuclear translocation of Nrf2. Furthermore, we performed SPECT imaging and evaluated the liver uptake value (LUV) to assess the extent of liver damage. LUV was observed to be lower in the ethanol group, whereas LUV was higher in control and M. olifera treated groups.

CONCLUSION

In summary, from this experiment we conclude that M. oleifera extract has the potential to ameliorate ethanol-induced liver damage.

TP53, CDKN2A/P16, and NFE2L2/NRF2 regulate the incidence of pure- and combined-small cell lung cancer in mice

Studies have shown that Nrf2^E79Q/+ is one of the most common mutations found in human tumors. To elucidate how this genetic change contributes to lung cancer, we compared lung tumor development in a genetically-engineered mouse model (GEMM) with dual Trp53/p16 loss, the most common mutations found in human lung tumors, in the presence or absence of Nrf2^E79Q/+. Trp53/p16-deficient mice developed combined-small cell lung cancer (C-SCLC), a mixture of pure-SCLC (P-SCLC) and large cell neuroendocrine carcinoma. Mice possessing the LSL-Nrf2^E79Q mutation showed no difference in the incidence or latency of C-SCLC compared with Nrf2^+/+ mice. However, these tumors did not express NRF2 despite Cre-induced recombination of the LSL-Nrf2^E79Q allele. Trp53/p16-deficient mice also developed P-SCLC, where activation of the NRF2^E79Q mutation associated with a higher incidence of this tumor type. All C-SCLCs and P-SCLCs were positive for NE-markers, NKX1-2 (a lung cancer marker) and negative for P63 (a squamous cell marker), while only P-SCLC expressed NRF2 by immunohistochemistry. Analysis of a consensus NRF2 pathway signature in human NE⁺-lung tumors showed variable activation of NRF2 signaling. Our study characterizes the first GEMM that develops C-SCLC, a poorly-studied human cancer and implicates a role for NRF2 activation in SCLC development.

Signaling pathways and their potential therapeutic utility in esophageal squamous cell carcinoma

Esophageal cancer is a complex gastrointestinal malignancy with an extremely poor outcome. Approximately 80% of cases of this malignancy in Asian countries including India are of squamous cell origin, termed Esophageal Squamous Cell Carcinoma (ESCC).The five-year survival rate in ESCC patients is less than 20%. Neo-adjuvant chemo-radiotherapy (NACRT) followed by surgical resection remains the major therapeutic strategy for patients with operable ESCC. However, resistance to NACRT and local recurrence after initial treatment are the leading cause of dismal outcomes in these patients. Therefore, an alternative strategy to promote response to the therapy and reduce the post-operative disease recurrence is highly needed. At the molecular level, wide variations have been observed in tumor characteristics among different populations, nevertheless, several common molecular features have been identified which orchestrate disease progression and clinical outcome in the malignancy. Therefore, determination of candidate molecular pathways for targeted therapy remains the mainstream idea of focus in ESCC research. In this review, we have discussed the key signaling pathways associated with ESCC, i.e., Notch, Wnt, and Nrf2 pathways, and their crosstalk during disease progression. We further discuss the recent developments of novel agents to target these pathways in the context of targeted cancer therapy. In-depth research of the signaling pathways, gene signatures, and a combinatorial approach may help in discovering targeted therapy for ESCC.

Dietary phenolic-type Nrf2-activators: implications in the control of toxin-induced hepatic disorders

Numerous studies have exemplified the importance of nuclear factor erythroid 2-related factor 2 (Nrf2) activation in the alleviation of toxin-induced hepatic disorders primarily through eliminating oxidative stress. Whereafter, increasingly more efforts have been contributed to finding Nrf2-activators, especially from dietary polyphenols. The present review summarized the phenolic-type Nrf2-activators published in the past few decades, analyzed their effectiveness based on their structural characteristics and outlined their related mechanisms. It turns out that flavonoids are the largest group of phenolic-type Nrf2-activators, followed by nonflavonoids and phenolic acids. When counting on subgroups, the top three types are flavonols, flavones, and hydroxycinnamic acids, with curcuminoids having the highest effective doses. Moreover, most polyphenols work through the phosphorylation of Nrf2. Besides, mitogen-activated protein kinases (MAPKs) and protein kinase B (Akt) are the frequent targets of these Nrf2-activators, which indirectly mediate the behavior of Nrf2. However, current data are not sufficient to conclude any structure-activity relationship.

Mutational Activation of the NRF2 Pathway Upregulates Kynureninase Resulting in Tumor Immunosuppression and Poor Outcome in Lung Adenocarcinoma

Activation of the NRF2 pathway through gain-of-function mutations or loss-of-function of its suppressor KEAP1 is a frequent finding in lung cancer. NRF2 activation has been reported to alter the tumor microenvironment. Here, we demonstrated that NRF2 alters tryptophan metabolism through the kynurenine pathway that is associated with a tumor-promoting, immune suppressed microenvironment. Specifically, proteomic profiles of 47 lung adenocarcinoma (LUAD) cell lines (11 KEAP1 mutant and 36 KEAP1 wild-type) revealed the tryptophan-kynurenine enzyme kynureninase (KYNU) as a top overexpressed protein associated with activated NRF2. The siRNA-mediated knockdown of NFE2L2, the gene encoding for NRF2, or activation of the NRF2 pathway through siRNA-mediated knockdown of KEAP1 or via chemical induction with the NRF2-activator CDDO-Me confirmed that NRF2 is a regulator of KYNU expression in LUAD. Metabolomic analyses confirmed KYNU to be enzymatically functional. Analysis of multiple independent gene expression datasets of LUAD, as well as a LUAD tumor microarray demonstrated that elevated KYNU was associated with immunosuppression, including potent induction of T-regulatory cells, increased levels of PD1 and PD-L1, and resulted in poorer survival. Our findings indicate a novel mechanism of NRF2 tumoral immunosuppression through upregulation of KYNU.

Antioxidant Activities and Mechanisms of Tomentosin in Human Keratinocytes

Tomentosin, one of natural sesquiterpene lactones sourced from Inula viscosa L., exerts therapeutic effects in various cell types. Here, we investigated the antioxidant activities and the underlying action mechanisms of tomentosin in HaCaT cells (a human keratinocyte cell line). Specifically, we examined the involvement of tomentosin in aryl hydrocarbon receptor (AhR) and nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathways. Treatment with tomentosin for up to 60 min triggered the production of reactive oxygen species (ROS), whereas treatment for 4 h or longer decreased ROS production. Tomentosin treatment also induced the nuclear translocation of Nrf2 and upregulated the expression of Nrf2 and its target genes. These data indicate that tomentosin induces ROS production at an early stage which activates the Nrf2 pathway by disrupting the Nrf2–Keap1 complex. However, at a later stage, ROS levels were reduced by tomentosin-induced upregulation of antioxidant genes. In addition, tomentosin induced the phosphorylation of mitogen-activated protein kinases (MAPKs) including p38 MAPK and c-Jun N-terminal kinase (JNK). SB203580 (a p38 MAPK inhibitor) and SP600125 (a JNK inhibitor) attenuated the tomentosin-induced phosphorylation of Nrf2, suggesting that JNK and p38 MAPK signaling pathways can contribute to the tomentosin-induced Nrf2 activation through phosphorylation of Nrf2. Furthermore, N-acetyl-_L-cysteine (NAC) treatment blocked both tomentosin-induced production of ROS and the nuclear translocation of Nrf2. These data suggest that tomentosin-induced Nrf2 signaling is mediated both by tomentosin-induced ROS production and the activation of p38 MAPK and JNK. Moreover, tomentosin inhibited the AhR signaling pathway, as evidenced by the suppression of xenobiotic-response element (XRE) reporter activity and the translocation of AhR into nucleus induced by urban pollutants, especially benzo[a]pyrene. These findings suggest that tomentosin can ameliorate skin damage induced by environmental pollutants.

Increased Supply of Methionine During a Heat-Stress Challenge in Lactating Holstein Cows Alters Mammary Tissue mTOR Signaling and its Response to Lipopolysaccharide

The first objective was to investigate the effects of feeding rumen-protected methionine (RPM) during a heat stress (HS) challenge on abundance and phosphorylation of mechanistic target of rapamycin (mTOR)-related signaling proteins in mammary gland. The second objective was to investigate how HS and RPM may modulate the response of mammary gland explants to lipopolysaccharide (LPS) stimulation. Thirty-two multiparous, lactating Holstein cows (184 ± 59 DIM) were randomly assigned to 1 of 2 environmental treatment groups, and 1 of 2 dietary treatments [TMR with RPM (Smartamine M; Adisseo Inc.; 0.105% DM as top dress) or TMR without RPM (CON)] in a crossover design. There were 2 periods with 2 phases per period. In phase 1 (9 d), all cows were in thermoneutral conditions (TN) and fed ad libitum. During phase 2 (9 d), group 1 (n = 16) was exposed to HS using electric heat blankets while group 2 (n = 16) remained in TN but were pair-fed to HS counterparts to control for DMI decreases associated with HS. After a washout period (14 d), the study was repeated (period 2). Environmental treatments were inverted in period 2 (sequence), while dietary treatments remained the same. Mammary tissue was harvested via biopsy at the end of both periods. Tissue was used for protein abundance analysis and also for incubation with 0 or 3 μg/mL of LPS for 2 h and subsequently used for mRNA abundance. Data were analyzed using PROC MIXED in SAS. Analysis of protein abundance data included the effects of diet, environment and their interaction, and period and sequence to account for the crossover design. The explant data model also included the effect of LPS and its interaction with environment and diet. Abundance of phosphorylated mTOR and ratio of phosphorylated eukaryotic translation elongation factor 2 (p-EEF2) to total EEF2 in non-challenged tissue was greater with RPM supplementation (P = 0.04 for both) and in both cases tended to be greater with HS (P = 0.08 for both). Regardless of RPM supplementation, incubation with LPS upregulated mRNA abundance of IL8, IL6, IL1B, CXCL2, TNF, NFKB1 and TLR2 (P < 0.05). An environment × LPS interaction was observed for NFKB1 (P = 0.03); abundance was greater in LPS-treated explants from non-HS compared with HS cows. Abundance of CXCL2, NFKB1, NOS2, NOS1, and SOD2 was lower with HS (P < 0.05). While LPS did not alter abundance of mRNA associated with the antioxidant transcription factor NFE2L2 signaling (P = 0.59), explants from HS cows had lower abundance of NFE2L2 (P < 0.001) and CUL3 (P = 0.04). Overall, RPM supplementation may alter mTOR activation. Additionally, while HS reduced explant immune and antioxidant responses, RPM did not attenuate the inflammatory response induced by LPS in vitro.

Intervening Effects and Molecular Mechanism of Quercitrin on PCV2-Induced Histone Acetylation, Oxidative Stress and Inflammatory Response in 3D4/2 Cells

Porcine circovirus type 2 (PCV2) is the main pathogen causing porcine circovirus-associated diseases (PCVD/PCVADs), and infection of the host induces immunosuppression. Since quercitrin (QUE) has anti-inflammatory and antiviral activity, it is worth exploiting in animal diseases. In this study, the interventional effects and the molecular mechanism of QUE on PCV2-induced oxidative stress and inflammatory responses in 3D4/2 cells and the modulation of histone acetylation modifications were investigated. The ROS production was measured by DCFH-DA fluorescent probes. HAT and HDAC enzyme activity were determined by ELISA. Histone acetylation, oxidative stress and inflammation-related gene expression levels were measured by q-PCR. Histone H3 and H4 (AcH3 and AcH4) acetylation, oxidative stress and inflammation-related protein expression levels were measured by Western blot. The results showed that QUE treatment at different concentrations on PCV2-infected 3D4/2 cells was able to attenuate the production of ROS. Moreover, QUE treatment could also intervene in oxidative stress and decrease the enzyme activity of HAT and the mRNA expression level of HAT1, while it increased the enzyme activity of HDAC and HDAC1 mRNA expression levels and downregulated histone H3 and H4 (AcH3 and AcH4) acetylation modification levels. In addition, QUE treatment even downregulated the mRNA expression levels of IL-6, IL-8, IκB, AKT and p38, but upregulated the mRNA expression levels of IL-10, SOD, GPx1, p65, Keap1, Nrf2, HO-1 and NQO1. As to protein expression, QUE treatment downregulated the levels of iNOS, p-p65 and IL-8 as well as the phosphorylation expression of IκB and p38, while it upregulated the levels of HO-1 and NQO1. It was shown that QUE at 25, 50 or 100 μmol/L regulated p38MAPK and PI3K/AKT signaling pathways by downregulating cellular histone acetylation modification levels while inhibiting the NF-κB inflammatory signaling pathway and activating the Nrf2/HO-1 antioxidant signaling pathway, thus regulating the production of inflammatory and antioxidant factors and exerting both anti-inflammatory and antioxidant effects.

Design, synthesis, biological evaluation and QSAR analysis of novel N-substituted benzimidazole derived carboxamides

As a result of our previous research focussed on benzimidazoles, herein we present design, synthesis, QSAR analysis and biological activity of novel N-substituted benzimidazole derived carboxamides. Carboxamides were designed to study the influence of the number of methoxy groups, the type of the substituent placed at the benzimidazole core on biological activity. Pronounced antioxidative activity displayed unsubstituted 28 (IC₅₀ ≈ 3.78 mM, 538.81 mmolFe²⁺/mmolC) and dimethoxy substituted derivative 34 (IC₅₀ ≈ 5.68 mM, 618.10 mmolFe²⁺/mmolC). Trimethoxy substituted 43 and unsubstituted compound 40 with isobutyl side chain at N atom showed strong activity against HCT116 (IC₅₀ ≈ 0.6 µM, both) and H 460 cells (IC₅₀ ≈ 2.5 µM; 0.4 µM), being less cytotoxic towards non-tumour cell. Antioxidative activity in cell generally confirmed relatively modest antioxidant capacity obtained in DPPH/FRAP assays of derivatives 34 and 40. The 3D-QSAR models were generated to explore molecular properties that have the highest influence on antioxidative activity.

Steatosis is involved in the progression of kidney disease in a high-fat-diet-induced non-alcoholic steatohepatitis mouse model

Chronic kidney disease (CKD) and non-alcoholic steatohepatitis (NASH) are major health issues associated with the metabolic syndrome. Although NASH is a known risk factor of CKD, the mechanisms linking these two diseases remain poorly understood. We aimed to investigate alterations in the kidney complicated with dyslipidemia in an established NASH mouse model. Male C57BL6/J mice were fed with control diet or high-fat diet (HFD), containing 40% fat, 22% fructose, and 2% cholesterol for 16 weeks. Metabolic characteristics, histological changes in the kidney, endoplasmic reticulum (ER) stress, apoptosis, and fibrosis were evaluated by histological analysis, immunoblotting, and quantitative reverse transcription-polymerase chain reaction. Levels of serum aspartate aminotransferase, alanine aminotransferase, alkali-phosphatase, total cholesterol, and urinary albumin were significantly higher in mice fed with HFD. Remarkable steatosis, glomerular hypertrophy, and interstitial fibrosis were also shown in in the kidney by leveraging HFD. Furthermore, HFD increased the mRNA expression levels of Casp3, Tgfb1, and Nfe2l2 and the protein level of BiP. We observed the early changes of CKD and speculate that the underlying mechanisms that link CKD and NASH are the induction of ER stress and apoptosis. Further, we observed the activation of Nfe2l2 in the steatosis-induced CKD mouse model. This NASH model holds implications in investigating the mechanisms linking dyslipidemia and CKD.

Dynamic modeling of Nrf2 pathway activation in liver cells after toxicant exposure

Cells are exposed to oxidative stress and reactive metabolites every day. The Nrf2 signaling pathway responds to oxidative stress by upregulation of antioxidants like glutathione (GSH) to compensate the stress insult and re-establish homeostasis. Although mechanisms describing the interaction between the key pathway constituents Nrf2, Keap1 and p62 are widely reviewed and discussed in literature, quantitative dynamic models bringing together these mechanisms with time-resolved data are limited. Here, we present an ordinary differential equation (ODE) based dynamic model to describe the dynamic response of Nrf2, Keap1, Srxn1 and GSH to oxidative stress caused by the soft-electrophile diethyl maleate (DEM). The time-resolved data obtained by single-cell confocal microscopy of green fluorescent protein (GFP) reporters and qPCR of the Nrf2 pathway components complemented with siRNA knock down experiments, is accurately described by the calibrated mathematical model. We show that the quantitative model can describe the activation of the Nrf2 pathway by compounds with a different mechanism of activation, including drugs which are known for their ability to cause drug induced liver-injury (DILI) i.e., diclofenac (DCF) and omeprazole (OMZ). Finally, we show that our model can reveal differences in the processes leading to altered activation dynamics amongst DILI inducing drugs.

Targeting NRF2 in Type 2 diabetes mellitus and depression: Efficacy of natural and synthetic compounds

Evidence supports a strong bidirectional association between depression and Type 2 diabetes mellitus (T2DM). The harmful impact of oxidative stress and chronic inflammation on the development of both disorders is widely accepted. Nuclear factor erythroid 2-related factor 2 (NRF2) is a pertinent target in disease management owing to its reputation as the master regulator of antioxidant responses. NRF2 influences the expression of various cytoprotective phase 2 antioxidant genes, which is hampered in both depression and T2DM. Through interaction and crosstalk with several signaling pathways, NRF2 endeavors to contain the widespread oxidative damage and persistent inflammation involved in the pathophysiology of depression and T2DM. NRF2 promotes the neuroprotective and insulin-sensitizing properties of its upstream and downstream targets, thereby interrupting and preventing disease advancement. Standard antidepressant and antidiabetic drugs may be powerful against these disorders, but unfortunately, they come bearing distressing side effects. Therefore, exploiting the therapeutic potential of NRF2 activators presents an exciting opportunity to manage such bidirectional and comorbid conditions.

Physical-Exercise-Induced Antioxidant Effects on the Brain and Skeletal Muscle

Erythroid-related nuclear factor 2 (NRF2) and the antioxidant-responsive-elements (ARE) signaling pathway are the master regulators of cell antioxidant defenses, playing a key role in maintaining cellular homeostasis, a scenario in which proper mitochondrial function is essential. Increasing evidence indicates that the regular practice of physical exercise increases cellular antioxidant defenses by activating NRF2 signaling. This manuscript reviewed classic and ongoing research on the beneficial effects of exercise on the antioxidant system in both the brain and skeletal muscle.

Potential Effects of Nrf2 in Exercise Intervention of Neurotoxicity Caused by Methamphetamine Oxidative Stress

Methamphetamine can cause oxidative stress-centered lipid peroxidation, endoplasmic reticulum stress, mitochondrial dysfunction, excitatory neurotoxicity, and neuroinflammation and ultimately lead to nerve cell apoptosis, abnormal glial cell activation, and dysfunction of blood-brain barrier. Protecting nerve cells from oxidative destroy is a hopeful strategy for treating METH use disorder. Nrf2 is a major transcriptional regulator that activates the antioxidant, anti-inflammatory, and cell-protective gene expression through endogenous pathways that maintains cell REDOX homeostasis and is conducive to the survival of neurons. The Nrf2-mediated endogenous antioxidant pathway can also prevent neurodegenerative effects and functional defects caused by METH oxidative stress. Moderate exercise activates this endogenous antioxidant system, which involves in many diseases, including neurodegenerative diseases. Based on evidence from existing literature, we argue that appropriate exercise can play an endogenous antioxidant regulatory role in the Nrf2 signaling pathway to reduce a number of issues caused by METH-induced oxidative stress. However, more experimental evidence is needed to support this idea. In addition, further exploration is necessary about the different effects of various parameters of exercise intervention (such as exercise mode, time, and intensity) on the Nrf2 signaling pathway intervention. Whether there are synergistic effects between exercise and plant-derived Nrf2 activators is worth further investigation.

Methylglyoxal Induces Inflammation, Metabolic Modulation and Oxidative Stress in Myoblast Cells

Uremic sarcopenia is a serious clinical problem associated with physical disability and increased morbidity and mortality. Methylglyoxal (MG) is a highly reactive, dicarbonyl uremic toxin that accumulates in the circulatory system in patients with chronic kidney disease (CKD) and is related to the pathology of uremic sarcopenia. The pathophysiology of uremic sarcopenia is multifactorial; however, the details remain unknown. We investigated the mechanisms of MG-induced muscle atrophy using mouse myoblast C2C12 cells, focusing on intracellular metabolism and mitochondrial injury. We found that one of the causative pathological mechanisms of uremic sarcopenia is metabolic flow change to fatty acid synthesis with MG-induced ATP shortage in myoblasts. Evaluation of cell viability revealed that MG showed toxic effects only in myoblast cells, but not in myotube cells. Expression of mRNA or protein analysis revealed that MG induces muscle atrophy, inflammation, fibrosis, and oxidative stress in myoblast cells. Target metabolomics revealed that MG induces metabolic alterations, such as a reduction in tricarboxylic acid cycle metabolites. In addition, MG induces mitochondrial morphological abnormalities in myoblasts. These changes resulted in the reduction of ATP derived from the mitochondria of myoblast cells. Our results indicate that MG is a pathogenic factor in sarcopenia in CKD.

The Interplay between Autophagy and Redox Signaling in Cardiovascular Diseases

Reactive oxygen and nitrogen species produced at low levels under normal cellular metabolism act as important signal molecules. However, at increased production, they cause damage associated with oxidative stress, which can lead to the development of many diseases, such as cardiovascular, metabolic, neurodegenerative, diabetes, and cancer. The defense systems used to maintain normal redox homeostasis plays an important role in cellular responses to oxidative stress. The key players here are Nrf2-regulated redox signaling and autophagy. A tight interface has been described between these two processes under stress conditions and their role in oxidative stress-induced diseases progression. In this review, we focus on the role of Nrf2 as a key player in redox regulation in cell response to oxidative stress. We also summarize the current knowledge about the autophagy regulation and the role of redox signaling in this process. In line with the focus of our review, we describe in more detail information about the interplay between Nrf2 and autophagy pathways in myocardium and the role of these processes in cardiovascular disease development.

Galactocerebrosidase deficiency induces an increase in lactosylceramide content: A new hallmark of Krabbe disease?

Galactocerebrosidase (GALC) hydrolyses galactose residues from various substrates, including galactosylceramide, psychosine (galactosylsphingosine), and lactosylceramide. Its severe deficiency has been associated with the accumulation of psychosine, a toxic molecule with detergent-like features, which alters membrane structures and signalling pathways, inducing the death of oligodendrocytes and a sequence of events in the nervous system that explain the appearance of many clinical signs typical of Krabbe disease. Nevertheless, new evidence suggests the existence of other possible links among GALC action, myelination, and myelin stability, apart from psychosine release. In this study, we demonstrated that lactosylceramide metabolism is impaired in fibroblasts isolated from patients with Krabbe disease in the absence of psychosine accumulation. This event is responsible for the aberrant and constitutive activation of the AKT/prolin-rich AKT substrate of 40 kDa (PRAS40) signalling axis, inducing B cell lymphoma 2 (BCL2) overexpression and glycogen synthase kinase 3 beta (GSK-3β) inhibition. In addition, nuclear factor E2-related factor 2 (NRF2) showed increased nuclear translocation. Due to the relevance of these molecular alterations in neurodegeneration, lactosylceramide increase should be evaluated as a novel marker of Krabbe disease, and because of its significant connections with signalling pathways.

Contribution of Müller Cells in the Diabetic Retinopathy Development: Focus on Oxidative Stress and Inflammation

Diabetic retinopathy is a neurovascular complication of diabetes and the main cause of vision loss in adults. Glial cells have a key role in maintenance of central nervous system homeostasis. In the retina, the predominant element is the Müller cell, a specialized cell with radial morphology that spans all retinal layers and influences the function of the entire retinal circuitry. Müller cells provide metabolic support, regulation of extracellular composition, synaptic activity control, structural organization of the blood-retina barrier, antioxidant activity, and trophic support, among other roles. Therefore, impairments of Müller actions lead to retinal malfunctions. Accordingly, increasing evidence indicates that Müller cells are affected in diabetic retinopathy and may contribute to the severity of the disease. Here, we will survey recently described alterations in Müller cell functions and cellular events that contribute to diabetic retinopathy, especially related to oxidative stress and inflammation. This review sheds light on Müller cells as potential therapeutic targets of this disease.

The principal molecular mechanisms behind the activation of Keap1/Nrf2/ARE pathway leading to neuroprotective action in Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder. PD is associated with the loss of dopaminergic neurons in the substantia nigra pars compacta region of the midbrain. Present therapies for PD provide only symptomatic relief by restoring the dopamine (DA) level. However, they are not disease modifying agents and so they do not delay the disease progression. Alpha-synuclein aggregation, oxidative stress, mitochondrial dysfunction and chronic inflammation are considered to be the major pathological mechanisms mediating neurodegeneration in PD. To resist oxidative stress, the human body has an antioxidant defence mechanism consisting of many antioxidants and cytoprotective genes. The expression of those genes are largely controlled by the Kelch-like ECH-associated protein 1/Nuclear factor - erythroid - 2 - related factor 2/Antioxidant response element (Keap1/Nrf2/ARE) signalling pathway. The transcription factor Nrf2 is activated in response to oxidative or electrophilic stress and protects the cells from oxidative stress and inflammation. Nrf2 has been widely considered as a therapeutic target for neurodegeneration and several drugs are now being tested in clinical trials. Regulation of the Keap1/Nrf2/ARE pathway by small molecules which can act as Nrf2 activators could be effective for treating oxidative stress and neuroinflammation in PD. In this review, we had discussed the principal molecular mechanisms behind the neuroprotective effects of Keap1/Nrf2/ARE pathway in PD. Additionally, we also discussed the small molecules and phytochemicals that could activate the Nrf2 mediated anti-oxidant pathway for neuroprotection in PD.

Early Effects of Extracellular Vesicles Secreted by Adipose Tissue Mesenchymal Cells in Renal Ischemia Followed by Reperfusion: Mechanisms Rely on a Decrease in Mitochondrial Anion Superoxide Production

Acute kidney injury (AKI) caused by ischemia followed by reperfusion (I/R) is characterized by intense anion superoxide (O₂^•−) production and oxidative damage. We investigated whether extracellular vesicles secreted by adipose tissue mesenchymal cells (EVs) administered during reperfusion can suppress the exacerbated mitochondrial O₂^•− formation after I/R. We used Wistar rats subjected to bilateral renal arterial clamping (30 min) followed by 24 h of reperfusion. The animals received EVs (I/R + EVs group) or saline (I/R group) in the kidney subcapsular space. The third group consisted of false-operated rats (SHAM). Mitochondria were isolated from proximal tubule cells and used immediately. Amplex Red™ was used to measure mitochondrial O₂^•− formation and MitoTracker™ Orange to evaluate inner mitochondrial membrane potential (Δψ). In vitro studies were carried out on human renal proximal tubular cells (HK-2) co-cultured or not with EVs under hypoxic conditions. Administration of EVs restored O₂^•− formation to SHAM levels in all mitochondrial functional conditions. The gene expression of catalase and superoxide dismutase-1 remained unmodified; transcription of heme oxygenase-1 (HO-1) was upregulated. The co-cultures of HK-2 cells with EVs revealed an intense decrease in apoptosis. We conclude that the mechanisms by which EVs favor long-term recovery of renal structures and functions after I/R rely on a decrease of mitochondrial O₂^•− formation with the aid of the upregulated antioxidant HO-1/Nuclear factor erythroid 2-related factor 2 system, thus opening new vistas for the treatment of AKI.

Randomized controlled trial of astaxanthin impacts on antioxidant status and assisted reproductive technology outcomes in women with polycystic ovarian syndrome

PURPOSE

Polycystic ovary syndrome (PCOS), the most common endocrinopathy in women, is typically accompanied by a defective oxidative defense system. Here, we investigated the effect of astaxanthin (AST) as a powerful antioxidant on the oxidative stress (OS) response and assisted reproductive technology (ART) outcomes in PCOS patients.

METHODS

In this double-blind, randomized, placebo-controlled trial, PCOS patients were randomly assigned into two groups. The intervention group received 8 mg AST, and the control group received the placebo daily for 40 days. The primary outcomes were the serum and follicular fluid (FF) levels of the OS biomarkers and the expression levels of the specific genes and proteins in the oxidative stress response pathway. The secondary outcomes were considered ART outcomes.

RESULTS

According to our findings, a 40-day course of AST supplementation led to significantly higher levels of serum CAT and TAC in the AST group compared to the placebo group. However, there were no significant intergroup differences in the serum MDA and SOD levels, as well as the FF levels of OS markers. The expression of Nrf2, HO-1, and NQ-1 was significantly increased in the granulosa cells (GCs) of the AST group. Moreover, the MII oocyte and high-quality embryo rate were significantly increased in the AST group compared to the placebo group. We found no significant intergroup difference in the chemical and clinical pregnancy rates.

CONCLUSION

AST treatment has been shown to increase both serum TAC levels and activation of the Nrf2 axis in PCOS patients' GCs.

TRIAL REGISTRATION

ClincialTrials.gov Identifier: NCT03991286.

Fatty Acid Metabolism and Cancer Immunotherapy

PURPOSE OF REVIEW

In this review, we update the latest findings on the impacts of FA metabolism reprogramming on the phenotypes and functions of immune cells in tumor-related immune responses. We also summarize the combinatorial interventions of FA metabolism, which improve the effects of current immunotherapies.

RECENT FINDINGS

Multiple studies have shown that either the abnormality in signaling pathways or nutrition competition in the TME can lead to phenotypic reprogramming of FA metabolism and functional changes in tumor-infiltrating immune cells, thereby influencing the therapeutic effects of cancer immunotherapies. Accordingly, regulating FA metabolism in immune cells has emerged and become promising approaches to synergize with immunotherapies. One of the mechanisms behind suboptimal therapeutic effects of immunotherapies is metabolic reprogramming of the TME that impairs immunosuppressive activity. FA metabolism is a crucial process involved in the survival and function of primary immune cells. It is of great significance to explore the feasibility of overcoming FA metabolic barriers to improve cancer immunotherapy.

Extract of Corallodiscus flabellata attenuates renal fibrosis in SAMP8 mice via the Wnt/β-catenin/RAS signaling pathway

BACKGROUND

Fibrosis is one of the most common pathological features of the aging process of the kidney, and fibrosis in aging kidneys also aggravates the process of chronic kidney disease (CKD). Corallodiscus flabellata B. L. Burtt (C. flabellata, CF) is a commonly used botanical drug in Chinese folklore. However, few studies have reported its pharmacological effects. This study aimed to explore the effect of CF ethanol extract on renal fibrosis in SAMP8 mice and identify potentially active compounds.

METHODS

Senescence-accelerated mouse-prone 8 (SAMP8) were used as animal models, and different doses of CF were given by gavage for one month. To observe the degree of renal aging in mice using β-galactosidase staining. Masson staining and the expression levels of Col-I, α-SMA, and FN were used to evaluate the renal fibrosis in mice. The protein expression levels of Nrf2 pathway and Wnt/β-catenin/RAS pathway in the kidney were measured. And β-galactosidase (β-gal) induced NRK-52E cells as an in vitro model to screen the active components of CF.

RESULTS

The CF ethanol extract significantly inhibited the activity of renal β-galactosidase and the expression levels of Col-I, α-SMA, and FN in SAMP8 mice, and improved Masson staining in SAMP8 mice. CF remarkably reduced urinary protein, creatinine, urea nitrogen and serum levels of TNF-α and IL-1β in SAMP8 mice, and significantly increased the levels of SOD and GSH-Px. Moreover, CF activated the Nrf2 pathway and blocked the Wnt/β-catenin/RAS pathway in the kidneys of mice. Besides, 3,4-dihydroxyphenylethanol (SDC-0-14, 16) and (3,4-dihydroxyphenylethanol-8-O-[4-O-trans-caffeoyl-β-D-apiofuranosyl-(1→3)-β-D-glucopyranosyl (1→6)]-β-D-glucopyranoside (SDC-1-8) were isolated from CF, which reduced the senescence of NRK-52E cells, and maybe the active ingredients of CF playing the anti-aging role.

CONCLUSIONS

Our experiments illuminated that CF ethanol extract may ameliorate renal fibrosis in SAMP8 mice via the Wnt/β-catenin/RAS pathway. And SDC-0-14,16 and SDC-1-8 may be the material basis for CF to exert anti-renal senescence-related effects.

Perinatal Hyperoxia and Developmental Consequences on the Lung-Brain Axis

Approximately 11.1% of all newborns worldwide are born preterm. Improved neonatal intensive care significantly increased survival rates over the last decades but failed to reduce the risk for the development of chronic lung disease (i.e., bronchopulmonary dysplasia (BPD)) and impaired neurodevelopment (i.e., encephalopathy of prematurity (EoP)), two major long-term sequelae of prematurity. Premature infants are exposed to relative hyperoxia, when compared to physiological in-utero conditions and, if needed to additional therapeutic oxygen supplementation. Both are associated with an increased risk for impaired organ development. Since the detrimental effects of hyperoxia on the immature retina are known for many years, lung and brain have come into focus in the last decade. Hyperoxia-induced excessive production of reactive oxygen species leading to oxidative stress and inflammation contribute to pulmonary growth restriction and abnormal neurodevelopment, including myelination deficits. Despite a large body of studies, which unraveled important pathophysiological mechanisms for both organs at risk, the majority focused exclusively either on lung or on brain injury. However, considering that preterm infants suffering from BPD are at higher risk for poor neurodevelopmental outcome, an interaction between both organs seems plausible. This review summarizes recent findings regarding mechanisms of hyperoxia-induced neonatal lung and brain injury. We will discuss common pathophysiological pathways, which potentially link both injured organ systems. Furthermore, promises and needs of currently suggested therapies, including pharmacological and regenerative cell-based treatments for BPD and EoP, will be emphasized. Limited therapeutic approaches highlight the urgent need for a better understanding of the mechanisms underlying detrimental effects of hyperoxia on the lung-brain axis in order to pave the way for the development of novel multimodal therapies, ideally targeting both severe preterm birth-associated complications.

Protection of Human Lens Epithelial Cells from Oxidative Stress Damage and Cell Apoptosis by KGF-2 through the Akt/Nrf2/HO-1 Pathway

Oxidative stress exerts a significant influence on the pathogenesis of various cataracts by inducing degradation and aggregation of lens proteins and apoptosis of lens epithelial cells. Keratinocyte growth factor-2 (KGF-2) exerts a favorable cytoprotective effect against oxidative stress in vivo and in vitro. In this work, we investigated the molecular mechanisms of KGF-2 against hydrogen peroxide- (H2O2-) induced oxidative stress and apoptosis in human lens epithelial cells (HLECs) and rat lenses. KGF-2 pretreatment could reduce H2O2-induced cytotoxicity as well as reactive oxygen species (ROS) accumulation. KGF-2 also increases B-cell lymphoma-2 (Bcl-2), quinine oxidoreductase-1 (NQO-1), superoxide dismutase (SOD2), and catalase (CAT) levels while decreasing the expression level of Bcl2-associated X (Bax) and cleaved caspase-3 in H2O2-stimulated HLECs. LY294002, the phosphatidylinositol-3-kinase (PI3K)/Akt inhibitor, abolished KGF-2's effect to some extent, demonstrating that KGF-2 protected HLECs via the PI3K/Akt pathway. On the other hand, KGF-2 activated the Nrf2/HO-1 pathway by regulating the PI3K/Akt pathway. Silencing nuclear factor erythroid 2-related factor 2 (Nrf2) by targeted-siRNA and inhibiting heme oxygenase-1 (HO-1) through zinc protoporphyrin IX (ZnPP) significantly decreased cytoprotection of KGF-2. Furthermore, as revealed by lens organ culture assays, KGF-2 treatment decreased H2O2-induced lens opacity in a concentration-dependent manner. As demonstrated by these data, KGF-2 resisted H2O2-mediated apoptosis and oxidative stress in HLECs through Nrf2/HO-1 and PI3K/Akt pathways, suggesting a potential protective effect against the formation of cataracts.

Regulation of the immune response to contact sensitizers by Nrf2

The skin is frequently exposed to chemical stress by organic chemicals or metal ions that can directly or indirectly challenge its immune components and may lead to T cell-mediated delayed type hypersensitivity reactions. The disruption of the skin's homeostasis by exposure to contact sensitizers can trigger an inflammatory immune response that results in eczema and allergic contact dermatitis. The recognition of these chemicals depends on Pattern Recognition Receptors expression on sentinel skin cells, mainly the innate resident immune cells orchestrating the skin's immune response and involving both oxidative and inflammatory pathways. The main driver of these both pathways is the Nrf2/Keap1 pathway, a major ubiquitous regulator of cellular oxidative and electrophilic stress, activated in various innate immune cells of the skin, including keratinocytes and epidermal Langerhans cells in the epidermis and dermal dendritic cells in the dermis. Nrf2 also shows a strong protective capacity by down-regulating inflammatory pathways. In this review, the important role of Nrf2 in the regulation of the immune response to contact sensitizers will be discussed and highlighted. This article is protected by copyright. All rights reserved.

Divergent Regulation of Decidual Oxidative-Stress Response by NRF2 and KEAP1 in Preeclampsia with and without Fetal Growth Restriction

Utero-placental development in pregnancy depends on direct maternal–fetal interaction in the uterine wall decidua. Abnormal uterine vascular remodeling preceding placental oxidative stress and placental dysfunction are associated with preeclampsia and fetal growth restriction (FGR). Oxidative stress is counteracted by antioxidants and oxidative repair mechanisms regulated by the transcription factor nuclear factor erythroid 2-related factor 2 (NRF2). We aimed to determine the decidual regulation of the oxidative-stress response by NRF2 and its negative regulator Kelch-like ECH-associated protein 1 (KEAP1) in normal pregnancies and preeclamptic pregnancies with and without FGR. Decidual tissue from 145 pregnancies at delivery was assessed for oxidative stress, non-enzymatic antioxidant capacity, cellular NRF2- and KEAP1-protein expression, and NRF2-regulated transcriptional activation. Preeclampsia combined with FGR was associated with an increased oxidative-stress level and NRF2-regulated gene expression in the decidua, while decidual NRF2- and KEAP1-protein expression was unaffected. Although preeclampsia with normal fetal growth also showed increased decidual oxidative stress, NRF2-regulated gene expression was reduced, and KEAP1-protein expression was increased in areas of high trophoblast density. The trophoblast-dependent KEAP1-protein expression in preeclampsia with normal fetal growth indicates control of decidual oxidative stress by maternal–fetal interaction and underscores the importance of discriminating between preeclampsia with and without FGR.

Upregulation of nuclear factor E2-related factor 2 (Nrf2) represses the replication of herpes simplex virus type 1

Background

Nuclear factor E2-related factor 2 (Nrf2) is an important transcription factor which plays a pivotal role in detoxifying reactive oxygen species (ROS) and has been more recently shown to regulate inflammatory and antiviral responses. However, the role of Nrf2 in Herpes Simplex Virus type 1 (HSV-1) infection is still unclear. In this study, the interaction between the Nrf2 and HSV-1 replication was investigated.

Methods

The levels of oxidative stress was monitored by using 8-hydroxy-2'-deoxyguanosine (8-OHdG) ELISA kits, and the dynamic changes of Nrf2-antioxidant response element (Nrf2-ARE) pathway were detected by Western Blot. The effect of Nrf2-ARE pathway on the regulation of HSV-1 proliferation was analyzed by Western Blot, Real-Time PCR and TCID₅₀ assay.

Results

HSV-1 infection induced oxidative stress. Nrf2 was activated, accompanied by the increase of its down-stream antioxidant enzyme heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase 1 (NQO1) in the early stage of HSV-1 infection. The proliferation of HSV-1 was inhibited by overexpression of Nrf2 or treatment with its activator tert-Butylhydroquinone (tBHQ). On the contrary, silencing of Nrf2 promotes virus replication. HO-1 is involved in the regulation of IFN response, leading to efficient anti-HSV-1 effects.

Conclusion

Our observations indicate that the Nrf2-ARE pathway activates a passive defensive response in the early stage of HSV-1 infection. Targeting the Nrf2 pathway demonstrates the potential for combating HSV-1 infection.

Transcription Factor Movement and Exercise-Induced Mitochondrial Biogenesis in Human Skeletal Muscle: Current Knowledge and Future Perspectives

In response to exercise, the oxidative capacity of mitochondria within skeletal muscle increases through the coordinated expression of mitochondrial proteins in a process termed mitochondrial biogenesis. Controlling the expression of mitochondrial proteins are transcription factors-a group of proteins that regulate messenger RNA transcription from DNA in the nucleus and mitochondria. To fulfil other functions or to limit gene expression, transcription factors are often localised away from DNA to different subcellular compartments and undergo rapid movement or accumulation only when required. Although many transcription factors involved in exercise-induced mitochondrial biogenesis have been identified, numerous conflicting findings and gaps exist within our knowledge of their subcellular movement. This review aims to summarise and provide a critical analysis of the published literature regarding the exercise-induced movement of transcription factors involved in mitochondria biogenesis in skeletal muscle.

Cytotoxic and Anti-Inflammatory Triterpenoids in the Vines and Leaves of Momordica charantia

The vines and leaves of Momordica charantia L. are used as herbal medicines to treat inflammation-related disorders. However, their safety profile remains uncharacterized, and the constituents in their extracts that exert anti-inflammatory and adverse effects remain unclear. This study isolated the characteristic cucurbitane-type triterpenoid species in the vines and leaves of M. charantia L. and analyzed their cytotoxicity, anti-inflammatory effects, and underlying mechanisms. Four structurally related triterpenoids—momordicines I, II, IV, and (23E) 3β,7β,25-trihydroxycucurbita-5,23-dien-19-al (TCD)—were isolated from the triterpenoid-rich fractions of extracts from the vines and leaves of M. charantia. Momordicine I was cytotoxic on normal cells, momordicine II exerted milder cytotoxicity, and momordicine IV and TCD had no obvious adverse effects on cell growth. TCD had anti-inflammatory activity both in vivo and in vitro. In lipopolysaccharide-stimulated RAW 264.7 cells, TCD inhibited the inhibitor kappa B kinase/nuclear factor-κB pathway and enhanced the expression of nuclear factor erythroid 2-related factor 2, heme oxygenase-1, and glutamate-cysteine ligase modifier subunit through the extracellular signal-regulated kinase1/2 and p38. Thus, the vines and leaves of M. charantia should be used with caution. An extraction protocol that can enrich TCD but remove momordicine I would likely enhance the safety of the extract.

Antioxidant Extract from Cleistocalyx nervosum var. paniala Pulp Ameliorates Acetaminophen-Induced Acute Hepatotoxicity in Rats

The indigenous purplish red fruit, Cleistocalyx nervosum var. paniala (CN), is grown in northern Thailand. The aqueous extract of CN pulp is known to exhibit antioxidant and anticarcinogenic properties. To search for an antioxidant fraction separated from CN, various hydroalcoholic extractions were performed. The acidified ethanolic extract of CN obtained from 0.5% (v/v) citric acid in 80% (v/v) ethanol yielded greater polyphenol content and DPPH radical scavenging activity when compared with other hydroethanolic extracts. Cyanidin-3-glucoside is a major anthocyanin present in the acidified ethanolic extract of CN (AECN). At a dose of 5000 mg/kg bw, an anthocyanin-rich extract was found to be safe when given to rats without any acute toxicity. To examine the hepatoprotective properties of AECN, an overdose of acetaminophen (APAP) was induced in a rat model, while silymarin was used as a standard reference. The administration of AECN at a dose of 300 mg/kg bw for 28 days improved hepatocyte architecture and modulated serum alanine aminotransferase levels in APAP-induced rats. Furthermore, it significantly decreased serum and hepatic malondialdehyde levels but increased hepatic glutathione content, as well as glutathione peroxidase and UDP-glucuronosyltransferase activities. In conclusion, AECN may effectively reduce oxidative stress induced acute hepatotoxicity in overdose APAP-treated rats through the suppression of oxidative stress and the enhancement of the antioxidant system in rat livers.

Salidroside alleviates oxidative stress and apoptosis via AMPK/Nrf2 pathway in DHT-induced human granulosa cell line KGN

In the past few years, emerging evidence established persistent oxidative stress to be a key player in the pathogenesis of polycystic ovary syndrome (PCOS). Particularly, it damages the function of granulosa cells, and thus hinders the development of follicles. The present study aimed to explore and establish the protective effects of salidroside on dihydrotestosterone (DHT)-induced Granulosa-like tumor cell line (KGN), mediated via antioxidant mechanisms. The study assessed the positive effects of salidroside on DHT-induced apoptosis, reactive oxygen species (ROS) accumulation, damage of antioxidant capacity, and mitochondrial membrane potential depolarization. Interestingly, salidroside partly reversed DHT mediated effects, via stimulation of nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway and the downstream antioxidant proteins heme oxygenase-1(HO-1) and quinine oxidoreductase 1(NQO1). Additionally, the knockdown of Nrf2 partly moderated the antioxidant and anti-apoptosis effects of salidroside in DHT-treated KGN cells. Mechanistically, AMP-activated protein kinase (AMPK) was identified to be the upstream signaling involved in salidroside-induced Nrf2 activation, as silencing of AMPK partly prevented the upregulation of Nrf2 and the downstream proteins HO-1 and NQO1. Altogether, the present study is the first to effectively demonstrate the inhibitory effect of salidroside on DHT-stimulated oxidative stress and apoptosis in KGN cells, which was dependent on Nrf2 activation that involved AMPK.

Astaxanthin as a Modulator of Nrf2, NF-κB, and Their Crosstalk: Molecular Mechanisms and Possible Clinical Applications

Astaxanthin (AST) is a dietary xanthophyll predominantly found in marine organisms and seafood. Due to its unique molecular features, AST has an excellent antioxidant activity with a wide range of applications in the nutraceutical and pharmaceutical industries. In the past decade, mounting evidence has suggested a protective role for AST against a wide range of diseases where oxidative stress and inflammation participate in a self-perpetuating cycle. Here, we review the underlying molecular mechanisms by which AST regulates two relevant redox-sensitive transcription factors, such as nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor κB (NF-κB). Nrf2 is a cellular sensor of electrophilic stress that coordinates the expression of a battery of defensive genes encoding antioxidant proteins and detoxifying enzymes. Likewise, NF-κB acts as a mediator of cellular stress and induces the expression of various pro-inflammatory genes, including those encoding cytokines, chemokines, and adhesion molecules. The effects of AST on the crosstalk between these transcription factors have also been discussed. Besides this, we summarize the current clinical studies elucidating how AST may alleviate the etiopathogenesis of oxidative stress and inflammation.

Age-Related Mitochondrial Impairment and Renal Injury Is Ameliorated by Sulforaphane via Activation of Transcription Factor NRF2

Age is one of the major risk factors for the development of chronic pathologies, including kidney diseases. Oxidative stress and mitochondrial dysfunction play a pathogenic role in aging kidney disease. Transcription factor NRF2, a master regulator of redox homeostasis, is altered during aging, but the exact implications of altered NRF2 signaling on age-related renal mitochondrial impairment are not yet clear. Herein, we investigated the role of sulforaphane, a well-known NRF2 activator, on age-related mitochondrial and kidney dysfunction. Young (2–4 month) and aged (20–24 month) male Fischer 344 rats were treated with sulforaphane (15 mg/kg body wt/day) in drinking water for four weeks. We observed significant impairment in renal cortical mitochondrial function along with perturbed redox homeostasis, decreased kidney function and marked impairment in NRF2 signaling in aged Fischer 344 rats. Sulforaphane significantly improved mitochondrial function and ameliorated kidney injury by increasing cortical NRF2 expression and activity and decreasing protein expression of KEAP1, an NRF2 repressor. Sulforaphane treatment did not affect the renal NRF2 expression or activity and mitochondrial function in young rats. Taken together, our results provide novel insights into the protective role of the NRF2 pathway in kidneys during aging and highlight the therapeutic potential of sulforaphane in mitigating kidney dysfunction in elders.

Revisiting the Oxidation of Flavonoids: Loss, Conservation or Enhancement of Their Antioxidant Properties

Flavonoids display a broad range of health-promoting bioactivities. Among these, their capacity to act as antioxidants has remained most prominent. The canonical reactive oxygen species (ROS)-scavenging mode of the antioxidant action of flavonoids relies on the high susceptibility of their phenolic moieties to undergo oxidation. As a consequence, upon reaction with ROS, the antioxidant capacity of flavonoids is severely compromised. Other phenol-compromising reactions, such as those involved in the biotransformation of flavonoids, can also markedly affect their antioxidant properties. In recent years, however, increasing evidence has indicated that, at least for some flavonoids, the oxidation of such residues can in fact markedly enhance their original antioxidant properties. In such apparent paradoxical cases, the antioxidant activity arises from the pro-oxidant and/or electrophilic character of some of their oxidation-derived metabolites and is exerted by activating the Nrf2–Keap1 pathway, which upregulates the cell’s endogenous antioxidant capacity, and/or, by preventing the activation of the pro-oxidant and pro-inflammatory NF-κB pathway. This review focuses on the effects that the oxidative and/or non-oxidative modification of the phenolic groups of flavonoids may have on the ability of the resulting metabolites to promote direct and/or indirect antioxidant actions. Considering the case of a metabolite resulting from the oxidation of quercetin, we offer a comprehensive description of the evidence that increasingly supports the concept that, in the case of certain flavonoids, the oxidation of phenolics emerges as a mechanism that markedly amplifies their original antioxidant properties. An overlooked topic of great phytomedicine potential is thus unraveled.

Effects of CEACAM1 in oral keratinocytes on HO-1 expression induced by Candida β-glucan particles

Objective

Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is a member of the carcinoembryonic antigen family. Although its expression has been found in chronic oral inflammatory epithelium, this study aimed to know whether CEACAM1 in oral keratinocytes participates in host immune response against Candida albicans .

Methodology

We investigated CEACAM1 expression in oral keratinocytes induced by C. albicans as well as by Candida cell wall component β-glucan particles (β-GPs). Furthermore, the effects of CEACAM1 on β-GPs-induced heme oxygenase-1 (HO-1) expression and its related signals were examined.

Results

Fluorescence staining showed CEACAM1 expression in oral keratinocytes (RT7) cells, whereas quantitative reverse transcription (RT)-PCR indicated that both live and heat-killed C. albicans increased CEACAM1 mRNA expression in RT7 cells. Examinations using quantitative RT-PCR and western blotting indicated that CEACAM1 expression was also increased by β-GPs derived from C. albicans . Specific siRNA for CEACAM1 decreased HO-1 expression induced by β-GPs from C. albicans as well as the budding yeast microorganism Saccharomyces cerevisiae . Moreover, knockdown of CEACAM1 decreased β-GPs-induced ROS activity in the early phase and translocation of Nrf2 into the nucleus.

Conclusion

CEACAM1 in oral keratinocytes may have a critical role in regulation of HO-1 for host immune defense during Candida infection.

Green perilla leaf extract ameliorates long-term oxidative stress induced by a high-fat diet in aging mice

BACKGROUND/OBJECTIVES

Oxidative stress is caused by an imbalance between harmful free radicals and antioxidants. Long-term oxidative stress can lead to an “exhausted” status of antioxidant defense system triggering development of metabolic syndrome and chronic inflammation. Green perilla (Perilla frutescens) is commonly used in Asian cuisines and traditional medicine in southeast Asia. Green perilla possesses numerous beneficial effects including anti-inflammatory and antioxidant functions. To investigate the potentials of green perilla leaf extract (PE) on oxidative stress, we induced oxidative stress by high-fat diet (HFD) in aging mice.

MATERIALS/METHODS

C57BL/6J male mice were fed HFD continuously for 53 weeks. Then, mice were divided into three groups for 12 weeks: a normal diet fed reference group (NDcon), high-fat diet fed group (HDcon), and high-fat diet PE treated group (HDPE, 400 mg/kg of body weight). Biochemical analyses of serum and liver tissues were performed to assess metabolic and inflammatory damage and oxidative status. Hepatic gene expression of oxidative stress and inflammation related enzymes were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

PE improved hepatopathology. PE also improved the lipid profiles and antioxidant enzymes, including hepatic glutathione peroxidase (GPx) and superoxide dismutase (SOD) and catalase (CAT) in serum and liver. Hepatic gene expressions of antioxidant and anti-inflammatory related enzymes, such as SOD-1, CAT, interleukin 4 (IL-4) and nuclear factor erythroid 2-related factor (Nrf2) were significantly enhanced by PE. PE also reduced the levels of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) in the serum and liver; moreover, PE suppressed hepatic gene expression involved in pro-inflammatory response; Cyclooxygenase-2 (COX-2), nitric oxide synthase (NOS), interleukin 1 beta (IL-1β), and interleukin 6 (IL-6).

CONCLUSIONS

This research opens opportunities for further investigations of PE as a functional food and possible anti-aging agent due to its attenuative effects against oxidative stress, resulting from HFD and aging in the future.