Nrf2-Keap1 signaling as a potential target for chemoprevention of inflammation-associated carcinogenesis

Designing Dual-Responsive Drug Delivery Systems: The Role of Phase Change Materials and Metal-Organic Frameworks

Stimuli-responsive drug delivery systems (DDSs) offer precise control over drug release, enhancing therapeutic efficacy and minimizing side effects. This review focuses on DDSs that leverage the unique capabilities of phase change materials (PCMs) and metal-organic frameworks (MOFs) to achieve controlled drug release in response to pH and temperature changes. Specifically, this review highlights the use of a combination of lauric and stearic acids as PCMs that melt slightly above body temperature, providing a thermally responsive mechanism for drug release. Additionally, this review delves into the properties of zeolitic imidazolate framework-8 (ZIF-8), a stable MOF under physiological conditions that decomposes in acidic environments, thus offering pH-sensitive drug release capabilities. The integration of these materials enables the fabrication of complex structures that encapsulate drugs within ZIF-8 or are enveloped by PCM layers, ensuring that drug release is tightly controlled by either temperature or pH levels, or both. This review provides comprehensive insights into the core design principles, material selections, and potential biomedical applications of dual-stimuli responsive DDSs, highlighting the future directions and challenges in this innovative field.

Involvement of the Keap1-Nrf2-ARE pathway in the antioxidant activity of sinomenine

Sinomenine is a pure alkaloid isolated from Sinomenium acutum. This study is aimed to investigate the critical role of the nuclear factor erythroid 2-related factor 2 (Nrf2)-kelch-like ECH-associated protein-1(Keap1)-antioxidant response element (ARE) antioxidative signaling pathway in protecting sinomenine against H2O2-induced oxidative injury. Cytotoxicity and antioxidant experiments to initially determine the protective effects of sinomenine show that sinomenine has no effect on the decreased cell viability and presents similar potency in scavenging all three free radicals. The binding affinity between sinomenine and Keap1 was determined via fluorescence polarization assay, with IC50 of 13.52 μM. Quantum chemical calculation and theoretical simulation illustrated that sinomenine located into the Nrf2-binding site of Keap1 via hydrophobic and hydrogen interactions, showing high stability and binding affinity. On the basis of the stable binding of sinomenine with Keap1, sinomenine efficiently induced nuclear translocation of Nrf2, and increased in ARE activity in a concentration-dependent manner. Quantitative polymerase chain reaction provided further evidences that sinomenine-induced protection upregulated ARE-dependent genes, such as NAD(P)H quinone oxidoreductase 1, hemeoxygenase-1, and glutamate-cysteine ligase modifier subunit. Western blot confirmed that sinomenine increased the expressions of these antioxidative enzymes. Taken together, in vitro and in silico evaluations demonstrate that sinomenine inhibits the binding of Keap1 to Nrf2, promotes the nuclear accumulation of Nrf2 and thus leads to the upregulated expressions of Nrf2-dependent antioxidative genes. Our findings also highlight the use of sinomenine for pharmacological or therapeutic regulation of the Nrf2-Keap1-ARE system, which is a novel strategy to prevent the progression of oxidative injury.

Advances in Nrf2 Signaling Pathway by Targeted Nanostructured-Based Drug Delivery Systems

Nanotechnology has gained significant interest in various applications, including sensors and therapeutic agents for targeted disease sites. Several pathological consequences, including cancer, Alzheimer's disease, autoimmune diseases, and many others, are mostly driven by inflammation and Nrf2, and its negative regulator, the E3 ligase adaptor Kelch-like ECH-associated protein 1 (Keap1), plays a crucial role in maintaining redox status, the expression of antioxidant genes, and the inflammatory response. Interestingly, tuning the Nrf2/antioxidant response element (ARE) system can affect immune-metabolic mechanisms. Although many phytochemicals and synthetic drugs exhibited potential therapeutic activities, poor aqueous solubility, low bioavailability, poor tissue penetration, and, consequently, poor specific drug targeting, limit their practical use in clinical applications. Also, the therapeutic use of Nrf2 modulators is hampered in clinical applications by the absence of efficient formulation techniques. Therefore, we should explore the engineering of nanotechnology to modulate the inflammatory response via the Nrf2 signaling pathway. This review will initially examine the role of the Nrf2 signaling pathway in inflammation and oxidative stress-related pathologies. Subsequently, we will also review how custom-designed nanoscale materials encapsulating the Nrf2 activators can interact with biological systems and how this interaction can impact the Nrf2 signaling pathway and its potential outcomes, emphasizing inflammation.

Nrf2/HO-1 signaling activation alleviates cigarette smoke-induced inflammation in chronic obstructive pulmonary disease by suppressing NLRP3-mediated pyroptosis

BACKGROUND

This study examined the effect of the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase 1 (HO-1) pathway on chronic obstructive pulmonary disease (COPD) and the potential molecular mechanism.

METHODS

A COPD mouse model was established by cigarette smoke exposure and administered with either ML385 or dimethyl fumarate (DMF). Airway resistance of mice was detected. IL-1β and IL-6 levels in mice alveolar lavage fluid were examined by enzyme-linked immunosorbent assay. Hematoxylin and eosin staining and immunohistochemical of lung tissues were utilized to detect lung injury and NLRP3 expression. DMF was used to treat COPD cell model constructed by exposing normal human bronchial epithelial (NHBE) cells to cigarette smoke extract. NHBE cells were transfected by NLRP3-expression vectors. Expression of proteins was detected by Western blot.

RESULTS

COPD mice showed the enhanced airway resistance, the inactivated Nrf2/HO-1 pathway and the overexpressed NLRP3, Caspase-1 and GSDMD-N proteins in lung tissues, and the increased IL-1β and IL-6 levels in alveolar lavage fluid. ML385 treatment augmented these indicators and lung injury in COPD mice. However, DMF intervention attenuated these indicators and lung injury in COPD mice. Nrf2/HO-1 pathway inactivation and overexpression of NLRP3, Caspase-1 and GSDMD-N proteins were observed in COPD cells. DMF intervention activated Nrf2/HO-1 pathway and down-regulated NLRP3, Caspase-1 and GSDMD-N proteins in COPD cells. However, NLRP3 overexpression abolished the effect of DMF on COPD cells.

CONCLUSION

Nrf2/HO-1 pathway activation may alleviate inflammation in COPD by suppressing the NLRP3-related pyroptosis. Activating the Nrf2/HO-1 pathway may be an effective method to treat COPD.

Acetyl barlerin from Barleria trispinosa induces chemopreventive NQO1 and attenuates LPS-induced inflammation: in vitro and molecular dynamic studies

Extraction and fractionation of Barleria trispinosa growing in Saudi Arabia yielded four iridoid compounds identified by spectroscopic techniques as acetylbarlerin (1), barlerin (2), shanzhiside methyl ester (3) and 6-⍺-L-rhamnopyranosyl-8-O-acetylshanzihiside methyl ester (4). Preliminary experiments confirmed that compound 1 acts as an inducer of chemopreventive NAD(P)H:Quinone oxidoreductase 1 (NQO1) enzymatic activity in a murine hepatoma (Hepa1c1c7) chemoprevention model. It also demonstrated the ability to inhibit the lipopolysaccharides (LPS)-induced nitric oxide (NO) production in the RAW264.7 macrophage model. Western blotting revealed the ability of compound 1 to up-regulate the protein expression of the NQO1 marker. Furthermore, compound 1 elicited NO suppression in RAW264.7 macrophages by inhibiting iNOS protein expression. Molecular docking and molecular simulation studies of 1 supported its experimental results as an inhibitor of the nuclear factor erythroid 2-Kelch-like ECH-associated protein 1 (Nrf2-KEAP1) complex, resulting in Nrf2-mediated induction of chemopreventive NQO1.Communicated by Ramaswamy H. Sarma.

The relationship between vaginal microenvironment and pelvic dysfunctional diseases in Chinese women: a systematic review and meta-analysis

OBJECTIVE

The aim of this review is to synthesize existing evidence on the combined effects of the vaginal microenvironment on pelvic dysfunctional diseases.

METHODS

This systematic review was conducted in accordance with the PRISMA guidelines. The PubMed, Embase, Cochrane Library, Web of Science, Wanfang, and China Knowledge Network (CNKI) databases were systematically searched up to January 2023 using the following MeSH terms: "pelvic organ prolapse", "stress urinary incontinence" and "vaginal microenvironment", "microenvironment", "vaginal cleanliness", "vaginitis", "lactobacillus" and other related keywords. Study methods were limited to case-control studies or cross-sectional studies. Quality assessment was performed using the Newcastle-Ottawa scale, and meta-analysis of the included literature was performed using Review Manager 5.3.

RESULTS

A total of eight articles were included in this systematic review (SR) and meta-analysis (MA), which involved a total of 7298 study participants. The pooled results of this meta-analysis showed that the vaginal microenvironment (number of vaginal lactobacilli, leukorrhea cleanliness, and presence of vaginitis) were all statistically significantly associated with pelvic dysfunctional diseases in Chinese women.

CONCLUSION

This review indicates that the vaginal microenvironment has an impact on the development of PFD in Chinese women.

TRIAL REGISTRATION

The protocol of this systematic review (SR) and meta-analysis (MA) has been registered in PROSPERO databases with the Registration number of CRD42023407251.

Unraveling the Nrf2-ARE Signaling Pathway in the DF-1 Chicken Fibroblast Cell Line: Insights into T-2 Toxin-Induced Oxidative Stress Regulation

The T-2 toxin (T2) poses a major threat to the health and productivity of animals. The present study aimed to investigate the regulatory mechanism of Nrf2 derived from broilers against T2-induced oxidative damage. DF-1 cells, including those with normal characteristics, as well as those overexpressing or with a knockout of specific components, were exposed to a 24 h treatment of 50 nM T2. The primary objective was to evaluate the indicators associated with oxidative stress and the expression of downstream antioxidant factors regulated by the Nrf2-ARE signaling pathway, at both the mRNA and protein levels. The findings of this study demonstrated a noteworthy relationship between the up-regulation of the Nrf2 protein and a considerable reduction in the oxidative stress levels within DF-1 cells (p < 0.05). Furthermore, this up-regulation was associated with a notable increase in the mRNA and protein levels of antioxidant factors downstream of the Nrf2-ARE signaling pathway (p < 0.05). Conversely, the down-regulation of the Nrf2 protein was linked to a marked elevation in oxidative stress levels in DF-1 cells (p < 0.05). Additionally, this down-regulation resulted in a significant decrease in both the mRNA and protein expression of antioxidant factors (p < 0.05). This experiment lays a theoretical foundation for investigating the detrimental impacts of T2 on broiler chickens. It also establishes a research framework for employing the Nrf2 protein in broiler chicken production and breeding. Moreover, it introduces novel insights for the prospective management of oxidative stress-related ailments in the livestock and poultry industry.

Modulation of inflammatory and oxidative stress biomarkers due to dexamethasone exposure in chicken splenocytes

Dexamethasone (DEXA) is a potent corticosteroid, commonly used for treating inflammatory, hypersensitive and allergic conditions. It is administered to birds with tumours. Many studies were conducted on its immunosuppressive effects; however none of the similar study is available employing chicken splenocytes culture system. The present study was conducted to assess DEXA induced alterations in inflammatory and oxidative stress biomarkers in chicken splenocytes due to its in vitro exposure. The maximum non-cytotoxic dose (MNCD) was evaluated and was further used for conducting lymphocytes proliferation assay (LPA), antioxidant assays (lipid peroxidation, GSH, superoxide dismutase and nitric oxide assays) and assessment of mRNA levels of various genes (IL-1β, IL-6, IL-10, LITAF, iNOS, NF-κB1, Nrf-2, Caspase-3 and -9) through qPCR. The MNCD was determined to be 30 ng/ml in chicken splenocytes culture system. DEXA caused reduction in B and T lymphocytes proliferation indicating its immunosuppressive effects, however improved the antioxidant status of the exposed splenocytes. The expression levels of IL-1β, IL-6, iNOS, LITAF and NF-κB1 were significantly reduced while IL-10 was enhanced, which signify potent anti-inflammatory potential of DEXA. NF-κB is a major transcription factor that regulates genes responsible for both, innate and adaptive immune responses and elicits inflammation. The nuclear factor erythroid 2-related factor 2 (Nrf-2) level was found to be up-regulated. Nrf-2 plays important role in combating the oxidant stress and its increased expression could be the reason of improved antioxidant status of DEXA exposed cells. Present findings indicated that DEXA exhibited modulation in anti-inflammatory, immunomodulatory and antioxidant mediators in chicken splenocytes.

The Triterpenoid CDDO-Methyl Ester Redirects Macrophage Polarization and Reduces Lung Tumor Burden in a Nrf2-Dependent Manner

The NRF2/KEAP1 pathway protects healthy cells from malignant transformation and maintains cellular homeostasis. Up to 30% of human lung tumors gain constitutive NRF2 activity which contributes to cancer cell survival and chemoresistance, but the effects of NRF2 activation in immune cells within the tumor microenvironment are underexplored. Macrophages can promote cancer progression or regression depending on context, and NRF2 activation affects macrophage activity. The NRF2 activator CDDO-Methyl ester (CDDO-Me or bardoxolone methyl) reprogrammed Nrf2 wild-type (WT) tumor-educated bone marrow-derived macrophages (TE-BMDMs) from a tumor-promoting to a tumor-inhibiting phenotype, marked by an increase in M1 markers TNFα, IL-6, and MHC-II and a decrease in the tumor-promoting factors VEGF, CCL2, and CD206. No changes were observed in Nrf2 knockout (KO) TE-BMDMs. CDDO-Me decreased tumor burden (p < 0.001) and improved pathological grade (p < 0.05) in WT but not Nrf2 KO A/J mice. Tumor burden in Nrf2 KO mice was 4.6-fold higher (p < 0.001) than in WT mice, irrespective of treatment. CDDO-Me increased the number of lung-infiltrating macrophages in WT mice but lowered CD206 expression in these cells (p < 0.0001). In summary, Nrf2 KO exacerbates lung tumorigenesis in A/J mice, and CDDO-Me promotes an Nrf2-dependent, anti-cancer macrophage phenotype.

Cineole regulates Wnt/β-catenin pathway through Nrf2/keap1/ROS to inhibit bisphenol A-induced apoptosis, autophagy inhibition and immunosuppression of grass carp hepatocytes

Bisphenol A (BPA), an environmental pollutant, can cause multiple organ tissue damage by inducing oxidative stress. Cineole (CIN) is a terpene oxide existing in a variety of plant essential oils, which has anti-inflammatory, analgesic, and antioxidant effects. This study examined the effects of 200 nM BPA and 20 μM CIN on apoptosis, autophagy, and immunology in grass carp hepatocytes (L8824). The treatments were categorized as NC, CIN, BPA + CIN, and BPA. The findings demonstrated that BPA exposure could increase ROS levels and oxidative stress-related indicators, decrease the expression of the Nrf2/keap1 pathway and the Wnt/β-catenin pathway, increase the expression of genes involved in the apoptotic pathway (Bax and Caspase3), and decrease the expression of the anti-apoptotic gene Bcl-2 by lowering mitochondrial membrane potential. BPA also reduced the expression of genes linked to autophagy (ATG5, Beclin1, LC3). Changes in immunological function after BPA exposure were also shown by changes in the amounts of antimicrobial peptides (HEPC, β-defensin, LEAP2) and cytokines (INF-γ, IL-1β, IL-2, and TNF-α). After the co-treatment of CIN and BPA, CIN can inhibit BPA-induced apoptosis and recover from autophagy and immune function to a certain extent by binding to keap1 to exert an anti-oxidative regulatory effect of Nrf2 incorporation into the nucleus. Molecular docking provides strong evidence for the interaction of CIN ligands with keap1 receptors. Therefore, these results indicated that CIN could inhibit BPA-induced apoptosis, autophagy inhibition and immunosuppression in grass carp hepatocytes by regulating the Wnt/β-catenin pathway with Nrf2/keap1/ROS. This study provided further information to the risk assessment of the neuroendocrine disruptor BPA on aquatic organisms and offered suggestions and resources for further research into the function of natural extracts in the body's detoxification process.

Gallic Acid Ameliorates Aspergillus Fumigatus Keratitis Through Reducing Fungal Load and Suppressing the Inflammatory Response

Purpose

The purpose of this study was to explore the antifungal and anti-inflammatory effects of gallic acid (GA) on Aspergillus fumigatus (A. fumigatus) keratitis.

Methods

CCK-8 assay and Draize eye test were used to determine the non-cytotoxic concentration of GA in RAW264.7 cells and an A. fumigatus keratitis mouse model. The antifungal effects of GA were analyzed using minimal inhibitory concentration (MIC), biofilm formation test, fungal adherence assay, calcofluor white staining, and propidium iodide staining. The therapeutic effects of GA were estimated by slit lamp photographs, clinical score, hematoxylin and eosin (H&E) staining, and Periodic acid-Schiff staining in vivo. Immunofluorescence staining and myeloperoxidase assay were conducted to identify neutrophil infiltration and activity. RT-PCR, ELISA, and Western blot were performed to detect the expression of pro-inflammatory cytokines and Nrf2/HO-1.

Results

In HCECs and A. fumigatus keratitis mouse model, GA at 100 µg/mL did not affect cell viability, thus this concentration was applied to subsequent experiments. In vitro, GA significantly inhibited A. fumigatus growth, biofilm formation, and adhesion. In vivo, 100 µg/mL GA alleviated the severity of fungal keratitis (FK) by repressing fungal load, reducing neutrophil infiltration, and lowering MPO activity. Besides, the expression of IL-1β, TNF-α, LOX-1, and COX-2 was inhibited, whereas Nrf2 and HO-1 expression was enhanced at both mRNA and protein levels in the 100 µg/mL GA treated group in comparison to PBS control.

Conclusions

GA ameliorates FK severity through inhibiting A. fumigatus load, reducing neutrophils infiltration, downregulating the expression of pro-inflammatory cytokines, and enhancing the Nrf2/HO-1 pathway, which provides new insight into A. fumigatus keratitis treatment.

Nrf2 signaling activation by a small molecule activator compound 16 inhibits hydrogen peroxide-induced oxidative injury and death in osteoblasts

We explored the potential activity of compound 16 (Cpd16), a novel small molecule Nrf2 activator, in hydrogen peroxide (H₂O₂)-stimulated osteoblasts. In the primary murine/human osteoblasts and MC3T3-E1 murine osteoblastic cells, Cpd16 treatment at micro-molar concentrations caused disassociation of Keap1-Nrf2 and Nrf2 cascade activation. Cpd16 induced stabilization of Nrf2 protein and its nuclear translocation, thereby increasing the antioxidant response elements (ARE) reporter activity and Nrf2 response genes transcription in murine and human osteoblasts. Significantly, Cpd16 mitigated oxidative injury in H₂O₂-stimulited osteoblasts. H₂O₂-provoked apoptosis as well as programmed necrosis in osteoblasts were significantly alleviated by the novel Nrf2 activator. Cpd16-induced Nrf2 activation and osteoblasts protection were stronger than other known Nrf2 activators. Dexamethasone- and nicotine-caused oxidative stress and death in osteoblasts were attenuated by Cpd16 as well. Cpd16-induced osteoblast cytoprotection was abolished by Nrf2 short hairpin RNA or knockout, but was mimicked by Keap1 knockout. Keap1 Cys151S mutation abolished Cpd16-induced Nrf2 cascade activation and osteoblasts protection against H₂O₂. Importantly, weekly Cpd16 administration largely ameliorated trabecular bone loss in ovariectomy mice. Together, Cpd16 alleviates H₂O₂-induced oxidative stress and death in osteoblasts by activating Nrf2 cascade.

Manganese Mitigates Heat Stress-Induced Apoptosis by Alleviating Endoplasmic Reticulum Stress and Activating the NRF2/SOD2 Pathway in Primary Chick Embryonic Myocardial Cells

Heat stress leads to oxidative stress and induces apoptosis in various cells. Endoplasmic reticulum (ER) stress is an important apoptosis pathway. Manganese (Mn) has been shown to enhance the activity of manganese superoxide dismutase (MnSOD). To explore the potential effect of Mn on ER stress and apoptosis induced by heat stress, we examined crucial factors associated with heat stress, ER stress, and apoptosis in cultured primary chick embryonic myocardial cells that had been pretreated with 20 μM Mn for 24 h and then subjected to 4 h of heat stress. The results showed that Mn decreased (P < 0.05) heat stress-induced reactive oxygen species (ROS) production and exerted antiapoptotic effects by increasing MnSOD enzymatic activity. The heat stress-induced accumulation of intracellular calcium was dramatically reduced (P < 0.05). Mn treatment significantly decreased (P < 0.05) the expression levels of the apoptosis-related gene Bax and ER stress markers glucose-regulated protein 78 (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP) in primary chick embryonic myocardial cells. Additionally, Mn reduced oxidative stress by activating the nuclear factor E2-related factor 2 (NRF2)/SOD2 signaling pathway. Taken together, our findings indicate that Mn attenuates heat stress-induced apoptosis by inhibiting ROS generation, intracellular calcium accumulation, and the ER stress pathway and activating the NRF2/SOD2 signaling pathway to protect myocardial cells from oxidative stress during chick embryonic development.

Dietary phytochemicals targeting Nrf2 for chemoprevention in breast cancer

Breast cancer accounts for 11.7% of all newly diagnosed cancer cases and has become the leading cause of cancer worldwide. Currently, more effective and less toxic chemopreventive strategies for breast cancer are urgently needed. Notably, naturally occurring dietary phytochemical compounds, such as curcumin and resveratrol, are generally considered to be the most promising breast cancer preventive agents. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that plays a key regulatory role in the expression of multiple antioxidant and anti-inflammatory enzymes, which can effectively suppress the excessive accumulation of carcinogens and their metabolites. Therefore, modulation of Nrf2 by dietary phytochemicals appears to be a promising approach for breast cancer prevention, which further removes excessive carcinogenic metabolites by inducing Phase II cytoprotective enzymes such as heme oxygenase-1 (HO-1) and NAD(P)H quinine oxidoreductase 1 (NQO1). In this review, we summarize recently published findings on the prevention of breast cancer with potential natural phytochemical compounds targeting Nrf2, as well as a mechanistic discussion of Nrf2 activation and its contribution in inhibiting breast cancer carcinogenesis. The epigenetic regulation of Nrf2 by phytochemicals is also explored.

Metformin alleviates chronic obstructive pulmonary disease and cigarette smoke extract-induced glucocorticoid resistance by activating the nuclear factor E2-related factor 2/heme oxygenase-1 signaling pathway

Chronic obstructive pulmonary disease (COPD) is an important healthcare problem worldwide. Often, glucocorticoid (GC) resistance develops during COPD treatment. As a classic hypoglycemic drug, metformin (MET) can be used as a treatment strategy for COPD due to its anti-inflammatory and antioxidant effects, but its specific mechanism of action is not known. We aimed to clarify the role of MET on COPD and cigarette smoke extract (CSE)-induced GC resistance. Through establishment of a COPD model in rats, we found that MET could improve lung function, reduce pathological injury, as well as reduce the level of inflammation and oxidative stress in COPD, and upregulate expression of nuclear factor E2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), multidrug resistance protein 1 (MRP1), and histone deacetylase 2 (HDAC2). By establishing a model of GC resistance in human bronchial epithelial cells stimulated by CSE, we found that MET reduced secretion of interleukin-8, and could upregulate expression of Nrf2, HO-1, MRP1, and HDAC2. MET could also increase the inhibition of MRP1 efflux by MK571 significantly, and increase expression of HDAC2 mRNA and protein. In conclusion, MET may upregulate MRP1 expression by activating the Nrf2/HO-1 signaling pathway, and then regulate expression of HDAC2 protein to reduce GC resistance.

Four-Octyl Itaconate Protects Chondrocytes against H2O2-Induced Oxidative Injury and Attenuates Osteoarthritis Progression by Activating Nrf2 Signaling

Nrf2 is a critical regulator of the antioxidant defense systems in cellular protection. Emerging evidence has shown that four-octyl itaconate (OI) activates Nrf2 cascade. In this study, the chondroprotective effects of OI on H₂O₂-stimulated chondrocytes and DMM-induced osteoarthritis (OA) progression were investigated. In primary murine chondrocytes, OI interrupted the binding of Keap1 and Nrf2, leading to accumulation and nuclear translocation of Nrf2 protein, as well as transcription and expression of Nrf2-dependent genes, such as HO-1, NQO1, and GCLC. Furthermore, OI inhibited cell death and apoptosis, as well as H₂O₂-stimulated ROS generation, lipid peroxidation, superoxide accumulation, and mitochondrial depolarization in chondrocytes, which were abolished by the silence or depletion of Nrf2. In addition, in vivo experiments revealed the therapeutic effects of OI on OA progression in a DMM mouse model. Collectively, these results suggested that OI might serve as a potential treatment for OA progression.

Fisetin, potential flavonoid with multifarious targets for treating neurological disorders: An updated review

Neurodegenerative disorders pose a significant health burden and imprint a debilitative impact on the quality of life. Importantly, aging is intricately intertwined with the progression of these disorders, and their prevalence increases with a rise in the aging population worldwide. In recent times, fisetin emerged as one of the potential miracle molecules to address neurobehavioral and cognitive abnormalities. These effects were attributed to its actions on several macromolecules and multiple molecular mechanisms. Fisetin belongs to a class of flavonoids, which is found abundantly in several fruits and vegetables. Fisetin has manifested several health benefits in preclinical models of neurodegenerative diseases such as Alzheimer's disease, Vascular dementia, and Schizophrenia. Parkinson's disease, Amyotrophic Lateral Sclerosis, Huntington's disease, Stroke, Traumatic Brain Injury (TBI), and age-associated changes. This review aimed to evaluate the potential mechanisms and pharmacological effects of fisetin in treating several neurological diseases. This review also provides comprehensive data on up-to-date recent literature and highlights the various mechanistic pathways pertaining to fisetin's neuroprotective role.

Nuclear Factor Erythroid 2-related Factor 2 Knockout Suppresses the Development of Aggressive Colorectal Cancer Formation Induced by Azoxymethane/Dextran Sulfate Sodium-Treatment in Female Mice

Colon tumors develop more frequently in male than in female. Nuclear factor erythroid 2-related factor 2 (Nrf2) plays differential roles in the stage of tumorigenesis. The purpose of this study was to investigate the role of Nrf2 on colitis-associated tumorigenesis using Nrf2 knockout (KO) female mice. Azoxymethane (AOM) and dextran sulfate sodium (DSS)-treated wild-type (WT) and Nrf2 KO female mice were sacrificed at week 2 and 16 after AOM injection. Severity of colitis, tumor incidence, and levels of inflammatory mediators were evaluated in AOM/DSS-treated WT and Nrf2 KO mice. Furthermore, qRT-PCR, Western blot abnalysis, and ELISA were performed in colon tissues. At week 2, AOM/DSS-induced colon tissue damages were significantly greater in Nrf2 KO than in WT mice. At week 16, tumor numbers (> 2 mm size) were significantly lower in both the proximal and distal colon in Nrf2 KO compared to WT. The overall incidences of adenoma/cancer of the proximal colon and submucosal invasive cancer of the distal colon were reduced by Nrf2 KO. The mRNA and protein expression levels of NF-κB-related mediators (i.e., iNOS and COX-2) and Nrf2-related antioxidants (i.e., heme oxygenase-1 and glutamate-cysteine ligase catalytic subunit) were significantly lower in the Nrf2 KO than in WT mice. Interestingly, the protein level of 15-hydroxyprostaglandin dehydrogenase (15-PGDH) was higher in AOM/DSS-treated Nrf2 KO than in WT mice. Our results support the oncogenic effect of Nrf2 in the later stage of carcinogenesis and upregulation of tumor suppressor 15-PGDH might contribute to the repression of colitis-associated tumorigenesis in Nrf2 KO female mice.

Drug delivery nanocarriers and recent advances ventured to improve therapeutic efficacy against osteosarcoma: an overview

BACKGROUND

Osteosarcoma (OS) is one of the key cancers affecting the bone tissues, primarily occurred in children and adolescence. Recently, chemotherapy followed by surgery and then post-operative adjuvant chemotherapy is widely used for the treatment of OS. However, the lack of selectivity and sensitivity to tumor cells, the development of multi-drug resistance (MDR), and dangerous side effects have restricted the use of chemotherapeutics.

MAIN BODY

There is an unmet need for novel drug delivery strategies for effective treatment and management of OS. Advances in nanotechnology have led to momentous progress in the design of tumor-targeted drug delivery nanocarriers (NCs) as well as functionalized smart NCs to achieve targeting and to treat OS effectively. The present review summarizes the drug delivery challenges in OS, and how organic nanoparticulate approaches are useful in overcoming barriers will be explained. The present review describes the various organic nanoparticulate approaches such as conventional nanocarriers, stimuli-responsive NCs, and ligand-based active targeting strategies tested against OS. The drug conjugates prepared with copolymer and ligand having bone affinity, and advanced promising approaches such as gene therapy, gene-directed enzyme prodrug therapy, and T cell therapy tested against OS along with their reported limitations are also briefed in this review.

CONCLUSION

The nanoparticulate drugs, drug conjugates, and advanced therapies such as gene therapy, and T cell therapy have promising and potential application in the effective treatment of OS. However, many of the above approaches are still at the preclinical stage, and there is a long transitional period before their clinical application.

Effect of antioxidants on preimplantation embryo development in vitro: a review

In vitro culture of the embryo is a useful method to treat infertility that shows embryo potential for selecting the best one to transfer and successfully implantation. However, embryo development in vitro is affected by oxidative stresses such as reactive oxygen species that may damage embryo development. Antioxidants are molecules found in fruits, vegetables, and fish that play an important role in reducing oxidative processes. In the natural environment, there is a physiological antioxidant system that protects embryos against oxidative damage. This antioxidant system does not exist in vitro. Antioxidants act as free radical scavengers and protect cells or repair damage done by free radicals. Various studies have shown that adding antioxidants into embryo culture medium improves embryo development in vitro. This review article emphasizes different aspects of various antioxidants, including types, functions and mechanisms, on the growth improvement of different species of embryos in vitro.

Solid Lipid Particles for Lung Metastasis Treatment

Solid lipid particles (SLPs) can sustainably encapsulate and release therapeutic agents over long periods, modifying their biodistribution, toxicity, and side effects. To date, no studies have been reported using SLPs loaded with doxorubicin chemotherapy for the treatment of metastatic cancer. This study characterizes the effect of doxorubicin-loaded carnauba wax particles in the treatment of lung metastatic malignant melanoma in vivo. Compared with the free drug, intravenously administrated doxorubicin-loaded SLPs significantly reduce the number of pulmonary metastatic foci in mice. In vitro kinetic studies show two distinctive drug release profiles. A first chemotherapy burst-release wave occurs during the first 5 h, which accounts for approximately 30% of the entrapped drug rapidly providing therapeutic concentrations. The second wave occurs after the arrival of the particles to the final destination in the lung. This release is sustained for long periods (>40 days), providing constant levels of chemotherapy in situ that trigger the inhibition of metastatic growth. Our findings suggest that the use of chemotherapy with loaded SLPs could substantially improve the effectiveness of the drug locally, reducing side effects while improving overall survival.

An Overview of Nrf2 Signaling Pathway and Its Role in Inflammation

Inflammation is a key driver in many pathological conditions such as allergy, cancer, Alzheimer’s disease, and many others, and the current state of available drugs prompted researchers to explore new therapeutic targets. In this context, accumulating evidence indicates that the transcription factor Nrf2 plays a pivotal role controlling the expression of antioxidant genes that ultimately exert anti-inflammatory functions. Nrf2 and its principal negative regulator, the E3 ligase adaptor Kelch-like ECH- associated protein 1 (Keap1), play a central role in the maintenance of intracellular redox homeostasis and regulation of inflammation. Interestingly, Nrf2 is proved to contribute to the regulation of the heme oxygenase-1 (HO-1) axis, which is a potent anti-inflammatory target. Recent studies showed a connection between the Nrf2/antioxidant response element (ARE) system and the expression of inflammatory mediators, NF-κB pathway and macrophage metabolism. This suggests a new strategy for designing chemical agents as modulators of Nrf2 dependent pathways to target the immune response. Therefore, the present review will examine the relationship between Nrf2 signaling and the inflammation as well as possible approaches for the therapeutic modulation of this pathway.

17β-Estradiol strongly inhibits azoxymethane/dextran sulfate sodium-induced colorectal cancer development in Nrf2 knockout male mice

Nuclear factor erythroid 2-related factor 2 (Nrf2) has dual effects on inflammation and cancer progression depending on the microenvironment. Estrogens have a protective effect on colorectal cancer (CRC) development. The aim of this study was to investigate CRC development in Nrf2 knockout (KO) mice. Azoxymethane (AOM) and dextran sulfate sodium (DSS)-treated wild-type (WT) and Nrf2 KO male mice were sacrificed at weeks 2 and 16 after AOM injection with/without 17β-estradiol (E2) treatment during week 1. Disease activity index and colon tissue damage at week 2 showed strong attenuation following E2 administration in WT mice but to a lesser extent in Nrf2 KO male mice. At week 16, E2 significantly diminished AOM/DSS-induced adenoma/cancer incidence at distal colon in the Nrf2 KO group, but not in the WT. Furthermore, mRNA or protein levels of NF-κB-related mediators (i.e., iNOS, TNF-α, and IL-1β) and Nrf2-related antioxidants (i.e., NQO1 and HO-1) were significantly lower in the Nrf2 KO group regardless of E2 treatment compared to the WT. The expression of estrogen receptor beta (ERβ) was higher in the Nrf2 KO group than in the WT. In conclusion, estrogen further inhibits CRC by upregulating ERβ-related alternate pathways in the absence of Nrf2.

FGF23 protects osteoblasts from dexamethasone-induced oxidative injury

Dexamethasone (DEX) can exert a cytotoxic effect on cultured osteoblasts. The current study explored the potential osteoblast cytoprotective effect of fibroblast growth factor 23 (FGF23). In OB-6 human osteoblastic cells and primary murine osteoblasts, FGF23 induced phosphorylation of the receptor FGFR1 and activated the downstream Akt-S6K1 signaling. FGF23-induced FGFR1-Akt-S6K phosphorylation was largely inhibited by FGFR1 shRNA, but augmented with ectopic FGFR1 expression in OB-6 cells. FGF23 attenuated DEX-induced death and apoptosis in OB-6 cells and murine osteoblasts. Its cytoprotective effects were abolished by FGFR1 shRNA, Akt inhibition or Akt1 knockout. Conversely, forced activation of Akt inhibited DEX-induced cytotoxicity in OB-6 cells. Furthermore, FGF23 activated Akt downstream nuclear-factor-E2-related factor 2 (Nrf2) signaling to alleviate DEX-induced oxidative injury. On the contrary, Nrf2 shRNA or knockout almost reversed FGF23-induced osteoblast cytoprotection against DEX. Collectively, FGF23 activates FGFR1-Akt and Nrf2 signaling cascades to protect osteoblasts from DEX-induced oxidative injury and cell death.

Roles of Reactive Oxygen Species in Biological Behaviors of Prostate Cancer

Prostate cancer (PCa), known as a heterogenous disease, has a high incidence and mortality rate around the world and seriously threatens public health. As an inevitable by-product of cellular metabolism, reactive oxygen species (ROS) exhibit beneficial effects by regulating signaling cascades and homeostasis. More and more evidence highlights that PCa is closely associated with age, and high levels of ROS are driven through activation of several signaling pathways with age, which facilitate the initiation, development, and progression of PCa. Nevertheless, excessive amounts of ROS result in harmful effects, such as genotoxicity and cell death. On the other hand, PCa cells adaptively upregulate antioxidant genes to detoxify from ROS, suggesting that a subtle balance of intracellular ROS levels is required for cancer cell functions. The current review discusses the generation and biological roles of ROS in PCa and provides new strategies based on the regulation of ROS for the treatment of PCa.

A Novel Kelch-Like-1 Is Involved in Antioxidant Response by Regulating Antioxidant Enzyme System in Penaeus vannamei

Heavy metals are typical cumulative pollutants that can enter and poison the human body through the food chain. However, the molecular mechanism of heavy metal-induced oxidative stress is unclear. In this study, we characterize PvKelch-like-1 from P. vannamei and explore its antioxidant roles in immune regulation of crustaceans. PvKelch-like-1 full length contains 2107 nucleotides, consists of a 5′ untranslated region (UTR) of 79 bp, a 3′ UTR of 180 bp, and a ORF of 1848 encoded 615 amino acids, which contain a BTB, BACK and Kelch motif, putative molecular mass and isoelectric point were 69 KDa and 6.54. PvKelch-like-1 mRNA was ubiquitously expressed in all detected tissue of P. vannamei, and mRNA expression levels were significantly up-regulated from 6 to 24 h after cadmium stress and reached the highest level (3.2-fold) at 12 h in the hepatopancreas. Subcellular localization analysis revealed that PvKelch-like-1 was localized in the nucleus. Silencing PvKelch-like-1 significantly increased reactive oxygen species (ROS) (1.61-fold) production and DNA damage (1.32-fold) in the shrimp hemolymph, and significantly decreased total hemocyte counts (THC) (0.64-fold) at 6 h in hemolymph. Additionally, the antioxidant genes PvCAT (0.43-fold), PvMnSOD (0.72-fold), PvGST (0.31-fold) and PvGPx (0.59-fold) at 6 h were decreased significantly in PvKelch-like-1 silenced shrimp after cadmium stress. Overexpression of PvKelch-like-1 has the opposite results in enzyme activity. The SOD (2.44-fold) and CAT (2.19-fold) activities were significantly increased after overexpressing PvKelch-like-1. These results suggest that PvKelch-like-1 plays a vital role in shrimp innate immune defense by positively regulating the expression of antioxidant enzyme genes to respond to cadmium stress.

Fish oil supplementation attenuates cognitive impairment by inhibiting neuroinflammation in STZ-induced diabetic rats

Type 2 diabetes mellitus (T2DM) markedly impairs human health. During T2DM development, some patients experience cognitive dysfunction and behavioral deficits, which are characterized by neuronal injury and memory loss. It has been reported that the incidence of dementia in middle-aged and elderly patients with diabetes is significantly higher than that in normal elderly patients. Currently, the pathogenesis of cognitive dysfunction in diabetes remains unknown, and there is no standard or specific method to diagnose the disease in clinical practice. Evidence has shown that fish oil (FO) can alleviate depressive-like behaviors by attenuating neuroinflammation in a rat model, and improve cognitive dysfunction by inhibiting apoptosis. Therefore, it is reasonable to speculate that FO may reduce cognitive impairment by attenuating neuroinflammation in diabetic rats. In the present study, we investigated the effects of FO supplementation on cognitive dysfunction in a streptozotocin-induced diabetic rat model. FO administration for 10 weeks improved spatial learning and memory as evaluated by performance in the Morris water maze (MWM). Besides, FO significantly improved the morphology of neurons in the hippocampus and cortex of diabetic rats and reduced the neuronal nuclear condensation. Moreover, FO decreased the mRNA expression of IL-1β, IL -6, and TNF-α and increased the mRNA expression of IL-4 and IL-10 in the cortex and hippocampus. FO also attenuated the brain inflammatory cascade and simultaneously reduced diabetes-induced oxidative stress. In addition, FO increased the protein expression of Nrf2 and HO-1 in cortex and hippocampus of diabetic rats. These results provide a novel horizon for the study of neuroprotective effect of FO and further clarify the connections among inflammation, oxidative stress and diabetes-induced cognitive impairment.

PGK1 inhibitor CBR-470-1 protects neuronal cells from MPP+

The neurotoxin MPP⁺ (1-methyl-4-phenylpyridinium ion) disrupts mitochondrial function leading to oxidative stress and neuronal death. Here we examine whether activation of the Keap1-Nrf2 cascade can protect SH-SY5Y neuroblastoma cells from MPP⁺-induced cytotoxicity. Treatment of SH-SY5Y cells with CBR-470-1, an inhibitor of the glycolytic enzyme phosphoglycerate kinase 1 (PGK1), leads to methylglyoxal modification of Keap1, Keap1-Nrf2 disassociation, and increased expression of Nrf2 responsive genes. Pretreatment with CBR-470-1 potently attenuated MPP⁺-induced oxidative injury and SH-SY5Y cell apoptosis. CBR-470-1 neuroprotection is dependent upon Nrf2, as Nrf2 shRNA or CRISPR/Cas9-mediated Nrf2 knockout, abolished CBR-470-1-induced SH-SY5Y cytoprotection against MPP⁺. Consistent with these findings, PGK1 depletion or knockout mimicked CBR-470-1-induced actions and rendered SH-SY5Y cells resistant to MPP⁺-induced cytotoxicity. Furthermore, activation of the Nrf2 cascade by CRISPR/Cas9-induced Keap1 knockout protected SH-SY5Y cells from MPP⁺. In Keap1 or PGK1 knockout SH-SY5Y cells,CBR-470-1 failed to offer further cytoprotection against MPP⁺. Collectively PGK1 inhibition by CBR-470-1 protects SH-SY5Y cells from MPP⁺ via activation of the Keap1-Nrf2 cascade.

Stimuli-Responsive Polymeric Nanocarriers for Drug Delivery, Imaging, and Theragnosis

In the past few decades, polymeric nanocarriers have been recognized as promising tools and have gained attention from researchers for their potential to efficiently deliver bioactive compounds, including drugs, proteins, genes, nucleic acids, etc., in pharmaceutical and biomedical applications. Remarkably, these polymeric nanocarriers could be further modified as stimuli-responsive systems based on the mechanism of triggered release, i.e., response to a specific stimulus, either endogenous (pH, enzymes, temperature, redox values, hypoxia, glucose levels) or exogenous (light, magnetism, ultrasound, electrical pulses) for the effective biodistribution and controlled release of drugs or genes at specific sites. Various nanoparticles (NPs) have been functionalized and used as templates for imaging systems in the form of metallic NPs, dendrimers, polymeric NPs, quantum dots, and liposomes. The use of polymeric nanocarriers for imaging and to deliver active compounds has attracted considerable interest in various cancer therapy fields. So-called smart nanopolymer systems are built to respond to certain stimuli such as temperature, pH, light intensity and wavelength, and electrical, magnetic and ultrasonic fields. Many imaging techniques have been explored including optical imaging, magnetic resonance imaging (MRI), nuclear imaging, ultrasound, photoacoustic imaging (PAI), single photon emission computed tomography (SPECT), and positron emission tomography (PET). This review reports on the most recent developments in imaging methods by analyzing examples of smart nanopolymers that can be imaged using one or more imaging techniques. Unique features, including nontoxicity, water solubility, biocompatibility, and the presence of multiple functional groups, designate polymeric nanocues as attractive nanomedicine candidates. In this context, we summarize various classes of multifunctional, polymeric, nano-sized formulations such as liposomes, micelles, nanogels, and dendrimers.

Luteolin induces mitochondrial apoptosis in HT29 cells by inhibiting the Nrf2/ARE signaling pathway

The aim of the current study was to investigate luteolin-induced apoptosis and the molecular mechanisms underlying it in HT29 cells. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to assess the cytotoxicity of luteolin on HT29 cells, and a dichloro-dihydro-fluorescein diacetate assay was used to measure cellular levels of reactive oxygen species (ROS). The effects of luteolin on the mitochondrial membrane potential were also evaluated. Bax and Bcl-2 mRNA expression were determined using reverse transcription-quantitative PCR. Additionally, western blot analysis was performed to assess changes in cytochrome c and caspase-3 protein expression. Localization of nuclear factor erythroid 2-related factor 2 (Nrf2) in the nucleus was also assessed using immunofluorescence. Luteolin exhibited cytotoxicity on HT29 cells in a time- and concentration-dependent manner. Additionally, ROS production was indicated to be increased and ROS scavenging was decreased, which resulted in a significant increase in the levels of ROS in the cells. The mitochondrial membrane potential was indicated to decrease following luteolin treatment. At the molecular level, luteolin significantly increased the mRNA expression of Bax and the protein expression of cytochrome c, caspase-3, p47phox and p22phox. The results revealed that luteolin decreased Bcl-2 protein expression and inhibited the nuclear localization of Nrf2. In conclusion, the current study indicated that luteolin inhibited HT29 cell proliferation and induced apoptosis via the mitochondrial pathway.

Keap1-targeting microRNA-941 protects endometrial cells from oxygen and glucose deprivation-re-oxygenation via activation of Nrf2 signaling

BACKGROUND

Mimicking ischemia-reperfusion injury, oxygen and glucose deprivation (OGD)-re-oxygenation (OGDR) applied to endometrial cells produces significant oxidative stress and programmed necrosis, which can be inhibited by nuclear-factor-E2-related factor 2 (Nrf2) signaling. MicroRNA (miRNA)-induced repression of Keap1, a Nrf2 suppressor protein that facilitates Nrf2 degradation, is novel strategy to activate Nrf2 cascade.

METHODS

MicroRNA-941 (miR-941) was exogenously expressed in HESC and primary human endometrial cells, and the Nrf2 pathway examined by Western blotting and real-time quantitative PCR analysis. The endometrial cells were treated with OGDR, cell programmed necrosis and apoptosis were tested.

RESULTS

MiR-941 is a novel Keap1-targeting miRNA that regulates Nrf2 activity. In T-HESC cells and primary human endometrial cells, ectopic overexpression of miR-941 suppressed Keap1 3'-UTR (untranslated region) expression and downregulated its mRNA/protein expression, leading to activation of the Nrf2 cascade. Conversely, inhibition of miR-941 elevated Keap1 expression and activity in endometrial cells, resulting in suppression of Nrf2 activation. MiR-941 overexpression in endometrial cells attenuated OGDR-induced oxidative stress and programmed necrosis, whereas miR-941 inhibition enhanced oxidative stress and programmed necrosis. MiR-941 overexpression and inhibition were completely ineffective in Keap1-/Nrf2-KO T-HESC cells (using CRISPR/Cas9 strategy). Restoring Keap1 expression, using an UTR-depleted Keap1 construct, abolished miR-941-induced anti-OGDR activity in T-HESC cells. Thus Keap1-Nrf2 cascade activation is required for miR-941-induced endometrial cell protection.

CONCLUSIONS

Targeting Keap1 by miR-941 activates Nrf2 cascade to protect human endometrial cells from OGDR-induced oxidative stress and programmed necrosis. Video Abstract.

Dimethyl itaconate protects against fungal keratitis by activating the Nrf2/HO-1 signaling pathway

Dimethyl itaconate (DI) is a membrane‐permeable itaconate derivative with anti‐inflammatory functions. However, the anti‐inflammatory effect of DI has never been studied in fungal keratitis. In this study, we tested the protective effect of DI against fungal keratitis and assessed the role of NF‐E2‐related factor‐2 (Nrf2)/heme oxygenase‐1 (HO‐1) signaling in this process. Eyes of C57BL/6 (B6) mice were treated with 2 mm DI after infection with Aspergillus fumigatus. Human corneal epithelial cells (HCECs) were pretreated with 0.25 mm DI and then incubated with A. fumigatus. Clinical scoring, slit‐lamp photography, myeloperoxidase determination, flow cytometry and immunostaining were used to assess the disease response and treatment efficacy. PCR, Western blot and ELISA were used to assess the expression of interleukin‐1β (IL‐1β), chemokine (C–X–C motif) ligand 1, IL‐6, IL‐8, Nrf2 and HO‐1. In addition, quantification of viable fungi, absorbance assays and fluorimetry were used to measure DI fungistatic activity. We observed that DI‐treated eyes showed decreased clinical scores, fungal loads, polymorphonuclear neutrophil (PMN) infiltration and cytokine expression, compared with phosphate‐buffered saline‐treated infected eyes. DI treatment decreased the cytokine levels in infected corneas and in HCECs stimulated with A. fumigatus. Moreover, DI treatment increased Nrf2 and HO‐1 expression in corneas and nuclear Nrf2 accumulation in HCECs. DI‐induced cytokine downregulation was inhibited by pretreatment with an Nrf2 or HO‐1 inhibitor. Finally, DI treatment reduced the A. fumigatus absorbance and fungal mass. These data indicate that DI protects against fungal keratitis by limiting inflammation via the Nrf2/HO‐1 signaling pathway and that DI inhibits the growth of A. fumigatus.

Effect of soybean peptides against hydrogen peroxide induced oxidative stress in HepG2 cells via Nrf2 signaling

The aim of this study was to determine the effects of soybean protein hydrolysates against intracellular antioxidant activity.

Lycium barbarum polysaccharides exert an antioxidative effect on rat chondrocytes by activating the nuclear factor (erythroid-derived 2)-like 2 signaling pathway

INTRODUCTION

Oxidative stress is the main cause of osteoarthritis (OA). Lycium barbarum polysaccharides (LBP) have antioxidant properties. Thus, the potential effect of LBP on H₂O₂-stimulated chondrocytes was examined.

MATERIAL AND METHODS

The cell viability was detected by CCK-8. The reactive oxygen species (ROS) production and apoptosis rates were determined by flow cytometric analysis. The DNA damage was detected by comet assay. Real-time polymerase chain reaction (qPCR) and Western blot assays were performed to examine the expression of histone 2A family member X (γH2AX), checkpoint kinase 1 (Chk1), poly ADP-ribose polymerase (PARP), cysteinyl aspartate specific proteinase (caspase)-3/8/9, and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and its antioxidant-response element (ARE) dependent factors including heme oxygenase-1 (HO-1) and quinine oxidoreductase-1 (NQO-1).

RESULTS

Compared to the H₂O₂ group, LBP inhibited the ROS production and DNA damage caused by H₂O₂ (p < 0.05), respectively. LBP inhibited the mRNA and protein expressions of γH2AX and Chk1 (p < 0.05). Meanwhile, LBP significantly decreased apoptosis (p < 0.05). And LBP inhibited the expression levels of PARP and Caspase-3/8/9 (p < 0.05). Moreover, LBP increased the expression of Nrf2, HO-1and NQO-1 (p < 0.05). Furthermore, the depletion of Nrf2 that mediated by RNA interference reversed the apoptosis and DNA damage inhibition effect of LBP (p < 0.05).

CONCLUSIONS

LBP protected chondrocytes through inhibiting DNA damage and apoptosis caused by H₂O₂, in which the Nrf2/ARE signaling pathway played a positive role. It provided an inspiration for clinical application - developing LBP as a therapeutic agent and Nrf2 as a promising candidate.

KMS99220 Exerts Anti-Inflammatory Effects, Activates the Nrf2 Signaling and Interferes with IKK, JNK and p38 MAPK via HO-1

Neuroinflammation is an important contributor to the pathogenesis of neurodegenerative disorders including Parkinson's disease (PD). We previously reported that our novel synthetic compound KMS99220 has a good pharmacokinetic profile, enters the brain, exerts neuroprotective effect, and inhibits NFκB activation. To further assess the utility of KMS99220 as a potential therapeutic agent for PD, we tested whether KMS99220 exerts an anti-inflammatory effect in vivo and examined the molecular mechanism mediating this phenomenon. In 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated mice, oral administration of KMS99220 attenuated microglial activation and decreased the levels of inducible nitric oxide synthase and interleukin 1 beta (IL-1b) in the nigrostriatal system. In lipopolysaccharide (LPS)-challenged BV-2 microglial cells, KMS99220 suppressed the production and expression of IL-1b. In the activated microglia, KMS99220 reduced the phosphorylation of IκB kinase, c-Jun N-terminal kinase, and p38 MAP kinase; this effect was mediated by heme oxygenase-1 (HO-1), as both gene silencing and pharmacological inhibition of HO-1 abolished the effect of KMS99220. KMS99220 induced nuclear translocation of the transcription factor Nrf2 and expression of the Nrf2 target genes including HO-1. Together with our earlier findings, our current results show that KMS99220 may be a potential therapeutic agent for neuroinflammation-related neurodegenerative diseases such as PD.

Berberine ameliorates CCl4‑induced liver injury in rats through regulation of the Nrf2‑Keap1‑ARE and p53 signaling pathways

Berberine (BBR) is an isoquinoline alkaloid, reported to have multiple pharmacological functions. However, its effects against CCl4‑induced oxidative damage remain poorly studied. Therefore, the present study investigated the protective action of BBR, and its antioxidant mechanisms, against CCl4‑induced liver injury in rats. A total of 48 rats were randomly arranged into six groups: Control; model; positive control (PC); BBR low‑dose (BL); BBR middle‑dose (BM); and BBR high‑dose (BH). The BL, BM and BH animals received BBR (5, 10 and 15 mg/kg by weight, respectively) orally for 7 consecutive days. Rats in the PC group were given silymarin (150 mg/kg), and the control and model groups were administered distilled water orally. At the end of the experiment, blood samples and livers were collected. To measure the liver biochemical indices, the reactive oxygen species (ROS) generation and the expression levels of related genes and protein, the following methods were used: An automatic biochemical analyzer; flow cytometry; spectrophotometry; reverse transcription‑quantitative PCR; western blotting; and hematoxylin and eosin staining. The results revealed that BBR significantly decreased the serum levels of alanine transaminase, aspartate transaminase and alkaline phosphatase, and increased those of glutathione and superoxide dismutase, but decreased malondialdehyde activity in hepatic tissue, and significantly decreased the reactive oxygen species level in hepatocytes. In hepatic tissue, the expressions of nuclear factor erythroid 2‑related factor 2 (Nrf2), kelch‑like ECH‑associated protein 1 (Keap-1), NAD(P)H quinone dehydrogenase 1 (NQO-1), heme oxygenase 1 (HO‑1), Bcl‑2 and Bcl‑xL mRNA, and HO‑1 protein were elevated, and the expression of p53 mRNA was decreased, particularly in the BH group (15 mg/kg). In conclusion, BBR exerts a protective action against CCl4‑induced acute liver injury in rats via effectively regulating the expression of Nrf2‑Keap1‑antioxidant responsive element‑related genes and proteins, and inhibiting p53 pathway‑mediated hepatocyte apoptosis.

17-β estradiol exerts anti-inflammatory effects through activation of Nrf2 in mouse embryonic fibroblasts

Several reports indicate crosstalk between the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and estrogen, which has a protective effect in colorectal cancer (CRC). The aim of this study was to investigate the role of Nrf2 signaling in the anti-inflammatory effect of estrogen using Nrf2 knockout (Nrf2 KO) mouse embryonic fibroblasts (MEFs), a powerful system to test the function of target genes due to their easy accessibility, and rapid growth rates. After inducing inflammation by tumor necrosis factor alpha (TNF-α), the effects of 17β-estradiol (E2) on the expression of proinflammatory mediators [i.e., NF-κB and inducible nitric oxide synthase (iNOS)] and estrogen receptors were evaluated by Western blot. In wild type (WT) MEFs, E2 treatment ameliorated TNF-α-induced nuclear translocation of NF-κB and expression of its target protein iNOS. Estrogen receptor beta (ERβ) expression was decreased by TNF-α-induced inflammation and restored by E2 treatment. When treated to WT MEFs, E2 induced nuclear translocation of Nrf2. The inhibitory effect of E2 on TNF-α-induced enhancement of iNOS was markedly dampened in Nrf2 KO MEFs. Notably, ERβ expression was significantly diminished in Nrf2 KO MEFs compared to that in WT cells. Promoter Database (EPD) revealed two putative anti-oxidant response elements (AREs) within the mouse ERβ promoter. Furthermore, in WT MEFs, E2 treatment repressed TNF-α-induced expression of iNOS protein and recovered by 4-(2-phenyl-5,7-bis(trifluoromethyl)pyrazolo(1,5-a)pyrimidin-3-yl)phenol (PHTPP), a selective ERβ antagonist, treatment, but not in Nrf2 KO MEFs. In conclusion, Nrf2 plays a pivotal role in the anti-inflammatory of estrogen by direct regulating the expression of ERβ.

Ajoene, a Major Organosulfide Found in Crushed Garlic, Induces NAD(P)H:quinone Oxidoreductase Expression Through Nuclear Factor E2-related Factor-2 Activation in Human Breast Epithelial Cells

Background

NAD(P)H:quinone oxidoreductase-1 (NQO1) is a widely-distributed flavin adenine dinucleotide-dependent flavoprotein that promotes obligatory 2-electron reductions of quinones, quinoneimines, nitroaromatics, and azo dyes. This reduces quinone levels and thereby minimizes generation of excess reactive oxygen species (ROS) formed by redox cycling, and concurrent depletion of intracellular thiol pools. Ajoene is derived from crushed garlic. It is formed by a reaction involving two allicin molecules, and is composed of allyl sulfide and vinyl disulfide. Ajoene is present in two isomers, E- and Z-form.

Methods

Expression of antioxidant enzymes and nuclear factor E2-related factor-2 (Nrf2) was measured by Western blot analysis. NQO1 promoter activity was assessed by the luciferase reporter gene assay. ROS accumulation was monitored by using the fluorescence-generating probe 2',7'-dichlorofluorescein diacetate. The intracellular glutathione levels were measured by using a commercially available kit.

Results

Z-ajoene significantly up-regulated the expression of representative antioxidant enzyme NQO1 in non-tumorigenic breast epithelial MCF-10A cells at non-toxic concentrations. Z-ajoene enhanced up-regulation and nuclear translocation of Nrf2, which plays a pivotal role in the induction of many genes encoding antioxidant enzymes and other cytoprotective proteins. Z-ajoene treatment also increased the activity of nqo1-promoter harboring antioxidant response element consensus sequences in MCF-10A cells. Silencing of Nrf2 by small interfering RNA abrogated ajoene-induced expression of NQO1. Z-ajoene activated extracellular signal-regulated kinase (ERK). Inhibition of ERK activation by U0126 abrogated ability of Z-ajoene to activate Nrf2 and to induce NQO1 expression. Intracellular ROS accumulation was observed after treatment with Z-ajoene, whereas the E-isoform was not effective. The inhibition of ROS by treatment with N-acetylcysteine, a radical scavenger, abrogated Z-ajoene-induced expression of NQO1 as well as activation of ERK and Nrf2, suggesting that Z-ajoene augments the Nrf2-dependent antioxidant defense via ROS generation and ERK activation.

Conclusions

Z-ajoene induces NQO1 expression in MCF-10A cells through ROS-mediated activation of Nrf2.

Dendrobium Officinale Polysaccharides Protect against MNNG-Induced PLGC in Rats via Activating the NRF2 and Antioxidant Enzymes HO-1 and NQO-1

Dendrobium officinale polysaccharides (DOP) are the main effective ingredient in Dendrobium officinale. Nuclear factor erythroid 2-related factor 2 (NRF2) signaling is regarded as an important way to mitigate the effects of reactive oxygen species (ROS) damage and inhibit gastric cancer progress. This study introduces a previously unknown effect of DOP on precancerous lesions of gastric cancer (PLGC). The mechanism discussed herein is based on the NRF2 signal pathway as well as its downstream antioxidant enzymes heme oxygenase-1 (HO-1) and NADPH quinone oxidoreductase-1 (NQO-1). DOP was prepared by the alcohol deposition method, and its molecular weight was determined using High-Performance Gel-Permeation Chromatography (HPGPC). Sixty male rats were randomly divided into five groups: normal control group (NC), PLGC model group (PLGC), model treated with low dose (2.4 g/kg) of DOP (L-DOP), model treated with middle dose (4.8 g/kg) of DOP (M-DOP), and model treated with high dose (9.6 g/kg) of DOP (H-DOP). DOP was orally administered to rats for 15 consecutive days prior to the start of a seven-month course of 1-methyl-3-nitro-1-nitrosoguanidine (MNNG) exposure. Histological evaluation was observed by hematoxylin and eosin (HE) and alcian blue/periodic acid-Schiff (AB-PAS) staining. Alanine aminotransferase (ALT), aspartate transaminase (AST), serum creatinine (Scr), serum uric acid (UA), blood urea nitrogen (BUN), and HE staining were detected for liver and kidney function. The level of 8-hydroxy-deoxyguanosine (8-OHdG) in serum was detected by kits. The NRF2 protein expression was detected by immunohistochemistry, and western blotting was utilized to compare differential protein expression levels among cytoplasmic and nuclear cell fractions. Expression levels of antioxidant enzymes heme oxygenase 1 (HO-1), Glutamate-Cysteine Ligase Catalytic Subunit (GCLC), Glutamate-Cysteine Ligase Modifier Subunit (GCLM), and NAD(P)H: quinone oxidoreductase-1 (NQO-1) were analyzed by reverse transcriptase polymerase chain reaction (RT-PCR); furthermore, the protein expression of NRF2, HO-1, and NQO-1 was detected by western blotting. The results showed that the average content of DOP is 83%, and its molecular weight is mainly contained within 3500 and 1000000. The H-DOP experimental group exhibited noticeable weight gain after seven months, reduced intestinal metaplasia, and made the atypical hyperplasia to be kept in moderate or mild degree. Data also showed DOP to be capable of decreasing levels of ALT, UA, and BUN, all of which had been elevated following the appearance of MNNG-induced PLGCs. DOP was also seen to reduce the expression of 8-OHdG and promote the expression of NRF2 in the gastric mucosa. Furthermore, RT-PCR and western blotting results showed that DOP upregulated the gene and protein expression of HO-1 and NQO-1. These findings show that DOP prevents MNNG-induced PLGC along with subsequent liver and kidney damage. The protective effects of DOP are associated with the reduction of 8-OHdG levels as well as the activation of the NRF2 pathway and its related antioxidant enzymes, HO-1 and NQO-1.

Nrf2/Keap1/ARE Signaling Mediated an Antioxidative Protection of Human Placental Mesenchymal Stem Cells of Fetal Origin in Alveolar Epithelial Cells

The oxidative stresses are a major insult in pulmonary injury such as acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), two clinical manifestations of acute respiratory failure with substantially high morbidity and mortality. Mesenchymal stem cells (MSCs) hold a promise in treatments of many human diseases, mainly owing to their capacities of immunoregulation and antioxidative activity. The strong immunoregulatory role of human placental MSCs of fetal origin (hfPMSCs) has been previously demonstrated; their antioxidant activity, however, has yet been interrogated. In this report, we examined the antioxidative activity of hfPMSCs by accessing the ability to scavenge oxidants and radicals and to protect alveolar epithelial cells from antioxidative injury using both a cell coculture model and a conditioned culture medium (CM) of hfPMSCs. Results showed a comparable antioxidative capacity of the CM with 100 μM of vitamin C (VC) in terms of the total antioxidant capacity (T-AOC), scavenging abilities of free radicals DPPH, hydroxyl radical (·OH), and superoxide anion radical (O₂⁻), as well as activities of antioxidant enzymes of SOD and GSH-PX. Importantly, both of the CM alone and cocultures of hfPMSCs displayed a protection of A549 alveolar epithelial cells from oxidative injury of 600 μM hydrogen peroxide (H₂O₂) exposure, as determined in monolayer and transwell coculture models, respectively. Mechanistically, hfPMSCs and their CM could significantly reduce the apoptotic cell fraction of alveolar epithelial A549 cells exposed to H₂O₂, accompanied with an increased expression of antiapoptotic proteins Bcl-2, Mcl-1, Nrf-2, and HO-1 and decreased proapoptotic proteins Bax, caspase 3, and Keap1, in comparison with naïve controls. Furthermore, hfPMSCs-CM (passage 3) collected from cultures exposed an inhibition of the Nrf2/Keap1/ARE signaling pathway which led to a significant reduction in caspase 3 expression in A549 cells, although the addition of Nrf2 inhibitor ML385 had no effect on the antioxidative activity of hfPMSCs-CM. These data clearly suggested that hfPMSCs protected the H₂O₂-induced cell oxidative injury at least in part by regulating the Nrf2-Keap1-ARE signaling-mediated cell apoptosis. Our study thus provided a new insight into the antioxidative mechanism and novel functions of hfPMSCs as antioxidants in disease treatments, which is warranted for further investigations.

Cancer: Thymoquinone antioxidant/pro-oxidant effect as potential anticancer remedy

Recently, there is growing interest in the natural bioactive components having anticancer activity. Thymoquinone (TQ), the principle active constituent of black seed (Nigella sativa), has promising properties including anticancer and chemosensitizing peculiarities. The anticancer power of TQ is accomplished by several aspects; including promotion of apoptosis, arrest of cell cycle and ROS generation. In addition, it boosts the immune system and lessens the side effects associated with traditional anticancer therapy. TQ also controls angiogenesis and cancer metastasis. This review focuses on the potential aspects and mechanisms by which TQ acquires its actions.

Transglycosylation Improved Caffeic Acid Phenethyl Ester Anti-Inflammatory Activity and Water Solubility by Leuconostoc mesenteroides Dextransucrase

Bioglycosylation is an efficient strategy to improve the biological activity and physicochemical properties of natural compounds for therapeutic drug development. In this study, two caffeic acid phenethyl ester (CAPE) glucosides (G-CAPE and 2G-CAPE) were synthesized by transglycosylation with dextransucrase from Leuconostoc mesenteroides 0326 with CAPE as an acceptor and sucrose as a donor. The products were purified and the structures were characterized. The physicochemical properties, anti-inflammatory activity, and cytotoxicity of the two CAPE glucosides were measured. The water solubility of G-CAPE and 2G-CAPE is 35 and 90 times higher, respectively, than that of CAPE. Compared to CAPE, the monoglycoside product showed superior anti-inflammatory effects, and its inhibition rate of NO, IF-6, and TNF-α is 93.4%, 76.81%, and 56.58% in RAW 264.7 macrophages, respectively, at 20 μM. Also, the cytotoxicity of both products was significantly improved. These glycosylation-modified CAPEs circumvent some of the flaws in CAPE application in anti-inflammatory drugs.

Endogenous and Exogenous Stimuli-Responsive Drug Delivery Systems for Programmed Site-Specific Release

In this study, we reviewed state-of-the-art endogenous-based and exogenous-based stimuli-responsive drug delivery systems (DDS) for programmed site-specific release to overcome the drawbacks of conventional therapeutic modalities. This particular work focuses on the smart chemistry and mechanism of action aspects of several types of stimuli-responsive polymeric carriers that play a crucial role in extracellular and intracellular sections of diseased tissues or cells. With ever increasing scientific knowledge and awareness, research is underway around the globe to design new types of stimuli (external/internal) responsive polymeric carriers for biotechnological applications at large and biomedical and/or pharmaceutical applications, in particular. Both external/internal and even dual/multi-responsive behavior of polymeric carriers is considered an essential element of engineering so-called 'smart' DDS, which controls the effective and efficient dose loading, sustained release, individual variability, and targeted permeability in a sophisticated manner. So far, an array of DDS has been proposed, developed, and implemented. For instance, redox, pH, temperature, photo/light, magnetic, ultrasound, and electrical responsive DDS and/or all in all dual/dual/multi-responsive DDS (combination or two or more from any of the above). Despite the massive advancement in DDS arena, there are still many challenging concerns that remain to be addressed to cover the research gap. In this context, herein, an effort has been made to highlight those concerning issues to cover up the literature gap. Thus, the emphasis was given to the drug release mechanism and applications of endogenous and exogenous based stimuli-responsive DDS in the clinical settings.

Stimulus-responsive nanoscale delivery systems triggered by the enzymes in the tumor microenvironment

The tumor microenvironment is the cellular environment that is also described as the "soil" for supporting tumor growth, proliferation, invasion and metastasis, as well as protecting tumor cells from immunological recognition. Notably, tumor cells can grow much faster than other normal organs and invade surrounding tissues more easily, which results in abnormal expression of enzymes in the tumor microenvironment, including matrix metalloproteinases, cathepsins, phospholipases, oxidoreductases, etc. In opposite, due to the high selectivity and catalytic activity, these enzymes can promote nanoparticles to recognize tumor tissues more accurately, and the more accumulation of drugs at primal tumor sites will enhance therapeutic efficacy with lower systemic toxicity. Therefore, one promising antitumor strategy is to design stimulus-responsive nanoscale delivery systems triggered by the enzymes with the support of various nanocarriers, such as liposomes, micelles and inorganic nanoparticles, etc. In this review, numerous facts were cited to summarize and discuss the typical types of enzyme-stimulus responsive nanoscale delivery systems. More importantly, we also focused on their recent advancements in antitumor therapy, and offered the direction for further studies.

Xiaochaihutang Inhibits the Activation of Hepatic Stellate Cell Line T6 Through the Nrf2 Pathway

Xiaochaihutang (XCHT) is one of classic prescriptions in Treatise on Febrile Diseases in China which was reported to have the effect of anti-hepatic fibrosis in vivo. Activation of hepatic stellate cells (HSCs) is now well established as a central driver of fibrosis in liver injury. Nuclear factor erythroid 2-related factor 2 (Nrf2) is an important element for anti-oxidative damage which is one of the key factors responsible for occurrence. This study was to investigate the effect of XCHT compound serum on HSCs activation and focus on the Nrf2 pathway. Rats in treatment groups were given the appropriate doses of XCHT granules (5 g/kg) and Silybin (50 mg/kg) for 6 days, and the serum were obtained. The compound serum was used to intervene HSCs. The results found that XCHT compound serum significantly inhibited the proliferation of HSCT6 cells. The number of α-SMA positive stained cells in HSCT6 cells and the content of Collagen type I (collagen-I) in supernatant were significantly decreased indicating suppression of activated HSCs. Compared with the control group, the nuclear transcription of Nrf2 and the expressions of Nqo1, GCLC, and GCLM were significantly increased in XCHT group. However, the effects of XCHT were inhibited in Nrf2-siRNA transfected HSCT6 cells. These studies demonstrated that XCHT could inhibit HSCT6 cell proliferation and activation. The mechanism might be related to up-regulation of the Nrf2 pathway against oxidative stress.

Drug screening assay based on the interaction of intact Keap1 and Nrf2 proteins in cancer cells

BACKGROUND

The Nrf2-Keap1 interaction is the major regulatory pathway for cytoprotective responses against oxidative and electrophilic stresses. Keap1, a substrate protein of a Cul3-dependent E3 ubiquitin ligase complex, is a negative regulator of Nrf2. The use of chemicals to regulate the interaction between Keap1 and Nrf2 has been proposed as a strategy for the chemoprevention of degenerative diseases and cancers.

RESULTS

The interactions between Keap1 and Nrf2 in vitro and in vivo were investigated using fluorescence resonance energy transfer (FRET) and bimolecular fluorescence complementation (BiFC) strategies in our study. Nrf2 with its N-terminal fused to eGFP and Keap1 with its C-terminal fused to mCherry were expressed and purified in vitro. When purified eGFP-Nrf2 and Keap1-mChrry proteins were mixed together, a strong FRET signal could be detected, indicating an efficient energy transfer from eGFP to mCherry. Moreover, the FRET was detected in vivo using confocal microscopy in colon cancer HCT-116 cells that were co-transfected with eGFP-Nrf2 and Keap1-mCherry. Finally, using an eGFP BiFC approach, the Keap1-Nrf2 interaction was also detected in MCF7 cells by transfecting eGFP N-terminal fused to Nrf2 (eN158-Nrf2) and eGFP C-terminal fused to Keap1 (eC159-Keap1). Using the BiFC and FRET systems, we demonstrated that the prototypical Nrf2-activiting compound tBHQ and the antitumor drug F-dUrd might interfere with the intracellular interaction between Keap1 and Nrf2 whereas the 5-Fu have little role in activating the protective response of Nrf2 pathway in cancer cells.

CONCLUSIONS

By analyzing the perturbation of the energy transfer between the donor and acceptor fluorophores and the bimolecular fluorescence complementation of eGFP, we can screen potential inhibitors for the interaction between Keap1 and Nrf2.