NRF2 targeting: a promising therapeutic strategy in chronic obstructive pulmonary disease

Auraptene Mitigates Cigarette Smoke and Lipopolysaccharide-Induced Chronic Obstructive Pulmonary Disease in Mice and BEAS-2B Cells via Regulating Keap1/Nrf2/HO-1 Pathway

Chronic obstructive pulmonary disease (COPD) is a most common respiratory condition characterized by airflow limitation, airway inflammation, and lung injury. The present study was undertaken to unveil the therapeutic potentials of the auroptene against lipopolysaccharide (LPS) and cigarette smoke (CS)-induced COPD in mice. The CS along with LPS was exposed to healthy C57BL/6 mice through the intranasal route to induce COPD. The exposure to CS was continued for 12 weeks. The LPS challenge was occurred on weeks 2, 4, 6, and 8. The auraptene was treated orally by gavage route 1 h before to CS exposure for last 4 weeks. After the completion of treatment, the respiratory function was assessed using a pulmonary function test equipment. The levels of mucin proteins, extracellular matrix (ECM) proteins, proliferative cytokine markers, epithelial marker protein E-cadherin, oxidative stress-related biomarkers, and inflammation-associated markers were assessed using respective commercial assay kits. An analysis of histopathology and histo-morphology was conducted on the pulmonary tissues. An in vitro assays were conducted on the CS condensate (CSC) and LPS-challenged BEAS-2B cells. The expressions of Keap1/Nrf2/HO-1 pathway associated proteins were assessed using assay kits. The findings of the current work has clearly proved that auraptene at 25 mg/kg concentrations significantly increased the pulmonary functions in the mice with COPD. The treatment of auraptene effectively reduced the ECM protein levels, proliferative cytokine marker levels, and inflammation-related cytokine levels in the COPD mice. In addition, the auraptene treatment effectively increased the antioxidants and mitigated the lung tissue injuries in the COPD mice. The Keap1/Nrf2/HO-1 signaling pathway expressions successfully regulated by the auraptene treatment in the CSC and LPS-induced BEAS-2B cells. Therefore, the current findings has highlighted that auraptene has the capability to be a beneficial intervention to treat COPD.

Cyclic vinyl sulfones activate NRF2 to protect from oxidative stress-induced programmed necrosis

The NRF2 transcriptional factor is a member of cellular stress response machinery and is activated in response to oxidative stress caused either by cellular homeostasis imbalance or by environmental challenges. NRF2 levels are stringently controlled by rapid and continuous proteasomal degradation. KEAP1 is a specific NRF2 binding protein that acts as a bridge between NRF2 and the E3 ligase Cullin-3. In this study, we examine model cyclic vinyl sulfone derivatives as potential NRF2 activating probes. Previously, we and other authors have found anti-inflammatory properties of these compounds in in vivo models; however, the mechanism of action remained unknown. Here, we show that the naphthohydroquinone derivative LCB1353 efficiently stabilizes NRF2 protein levels and upregulates its target genes. At low 5-10 µM concentrations LCB1353 protects non-small cell lung cancer H1299 cells from ferroptotic death induced by cytotoxic concentrations of RSL3, reducing cell death from 90 % to 5 %. Thus, we suggest that cyclic vinyl sulfones are promising scaffolds for the design of protective molecules for conditions associated with toxic and inflammatory levels of oxidative stress.

EGCG-Modified Bioactive Core-Shell Fibers Modulate Oxidative Stress to Synergistically Promote Vascularized Bone Regeneration

Oxidative stress induced by reactive oxygen species (ROS) can adversely affect tissue repair, whereas endowing biomaterials with antioxidant activity can improve the in vivo microenvironment, thereby promoting angiogenesis and osteogenesis. Accordingly, this study utilized epigallocatechin-3-gallate (EGCG), a material known for its reducing properties, oxidative self-polymerization capability, and strong binding characteristics, to modify a bioactive core-shell fibrous membrane (10RP-PG). Compared to the 10RP-PG fibrous membrane, the EGCG-modified fibrous membrane (E/10RP-PG) exhibited superior hydrophilicity, excellent cell adhesion, and compatibility. Moreover, the EGCG-modified fibrous membrane can effectively scavenge free radicals, ameliorate the local microenvironment, and foster angiogenesis (enhancing the expression of angiogenic genes in human umbilical vein endothelial cells (HUVECs) by 1.58 times and promoting vascular generation area upon subcutaneous implantation by 4.47 times). The enhancement of angiogenic activity of the E/10RP-PG fibrous membrane further promoted cartilage degeneration and absorption, as well as new bone formation, thus facilitating the repair of bone defects. This study provides a new strategy for promoting bone defect repair through the surface modification of biomaterials with an antioxidant agent, and the fabricated E/10RP-PG fibrous membranes show promise for guiding vascularized bone regeneration.

Flavonoid intakes, chronic obstructive pulmonary disease, adult asthma, and lung function: a cohort study in the UK Biobank

BACKGROUND

Given their antioxidative stress, anti-allergic, anti-inflammatory, and immune-modulating effects, flavonoids are hypothesized to play a role in preventing chronic obstructive pulmonary disease (COPD) and asthma.

OBJECTIVES

This cohort study aimed to examine associations between flavonoid intake and COPD, asthma, and lung function.

METHODS

Among 119,466 participants of the UK Biobank, median [interquartile range] age of 60 [53, 65] y, we estimated intakes of flavonoids, flavonoid-rich foods, and a flavodiet score from 24-h diet assessments. Prospective associations with both incident COPD and asthma and cross-sectional associations with measures of lung function [%predicted forced expiratory volume in 1s (FEV1); and FEV1/forced vital capacity (FVC)] were examined using multivariable-adjusted Cox proportional hazards and linear regression models, respectively. We investigated mediation by inflammation--represented by the INFLA score--and stratified analyses by smoking status.

RESULTS

Compared with low intakes, moderate intakes of total flavonoids, flavonols, theaflavins + thearubigins, and flavanones, and moderate-to-high intakes of flavanol monomers, proanthocyanidins, anthocyanins, flavones, and the flavodiet score were associated with up to an 18% lower risk of incident COPD {e.g., [hazard ratio (95% confidence interval) for total flavonoids: 0.83 (0.75, 0.92)]} but not incident asthma. Furthermore, compared with low intakes, higher intakes of all flavonoid subclasses (except theaflavins + thearubigins), and the flavodiet score were associated with better percent predicted FEV1 baseline. Associations were most apparent in ever (current or former) smokers. Flavonoid intakes were inversely associated with the INFLA score, which appeared to mediate 11%-14% of the association between intakes of proanthocyanidins and flavones and incident COPD.

CONCLUSIONS

Moderate-to-high flavonoid intakes were associated with a lower risk of COPD and better lung function, particularly among ever smokers. Promoting intakes of healthy flavonoid-rich foods, namely, tea, apples, and berries, may improve respiratory health and lower COPD risk, particularly in individuals with a smoking history.

Association between dietary anthocyanin intake and chronic obstructive pulmonary disease in US adults: A public database survey

BACKGROUND

Anthocyanins have anti-inflammatory and antioxidant properties. Several studies have demonstrated that anthocyanins are associated with many chronic diseases, but few studies have focused on the relationship between anthocyanins and chronic obstructive pulmonary disease (COPD).

OBJECTIVES

This survey aimed to explore the relationship between dietary anthocyanin intake and COPD in US adults over the age of 40.

METHODS

A cross-sectional study from the National Health and Nutrition Examination Survey (NHANES) 2017-2018 was conducted. We used univariate and multivariate logistic regression and restricted cubic spline (RCS) to analyze the relationship between dietary anthocyanins and COPD. Subgroup and interaction analyses were adopted to assess whether there were differences in the relationship between dietary anthocyanin intake and COPD in different groups.

RESULTS

A total of 2862 participants aged ≥ 40 years were analyzed, of whom 213 were diagnosed with COPD. The highest tertile of dietary anthocyanin intake was negatively correlated with COPD compared to the lowest after adjusting potential confounders (Model 1, OR = 0.414; 95% CI: (0.245, 0.699), P-trend = 0.002; Model 2, OR = 0.363; 95% CI: (0.210, 0.627), P-trend = 0.002; Model 3, OR = 0.614; 95% CI: (0.383, 0.985), P-trend = 0.040). The RCS curve showed a significant inverse linear relationship between dietary anthocyanin intake and COPD (P non-linear = 0.734). In subgroup analyses, the negative correlation between dietary anthocyanin intake and COPD existed across different subgroups.

CONCLUSION

Our study indicated that higher dietary anthocyanins are a protective factor against the presence of COPD in the US aged over 40.

Transcription factor NF-E2-related factor 2 plays a critical role in acute lung injury/acute respiratory distress syndrome (ALI/ARDS) by regulating ferroptosis

NRF2 is an important transcription factor that regulates redox homeostasis in vivo and exerts its anti-oxidative stress and anti-inflammatory response by binding to the ARE to activate and regulate the transcription of downstream protective protein genes, reducing the release of reactive oxygen species. Ferroptosis is a novel iron-dependent, lipid peroxidation-driven cell death mode, and recent studies have shown that ferroptosis is closely associated with acute lung injury/acute respiratory distress syndrome (ALI/ARDS). NRF2 is able to regulate ferroptosis through the regulation of the transcription of its target genes to ameliorate ALI/ARDS. Therefore, This article focuses on how NRF2 plays a role in ALI/ARDS by regulating ferroptosis. We further reviewed the literature and deeply analyzed the signaling pathways related to ferroptosis which were regulated by NRF2. Additionally, we sorted out the chemical molecules targeting NRF2 that are effective for ALI/ARDS. This review provides a relevant theoretical basis for further research on this theory and the prevention and treatment of ALI/ARDS. The intended audience is clinicians and researchers in the field of respiratory disease.

DACH1 Attenuates Airway Inflammation in Chronic Obstructive Pulmonary Disease by Activating NRF2 Signaling

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease of the airways characterized by impaired lung function induced by cigarette smoke (CS). Reduced DACH1 (dachshund homolog 1) expression has a detrimental role in numerous disorders, but its role in COPD remains understudied. This study aimed to elucidate the role and underlying mechanism of DACH1 in airway inflammation in COPD by measuring DACH1 expression in lung tissues of patients with COPD. Airway epithelium-specific DACH1-knockdown mice and adenoassociated virus-transfected DACH1-overexpressing mice were used to investigate the role of DACH1 and the potential for therapeutic targeting in experimental COPD caused by CS. Furthermore, we discovered a potential mechanism of DACH1 in inflammation induced by CS extract stimulation in vitro. Compared with nonsmokers and smokers without COPD, patients with COPD had reduced DACH1 expression, especially in the airway epithelium. Airway epithelium-specific DACH1 knockdown aggravated airway inflammation and lung function decline caused by CS in mice, whereas DACH1 overexpression protected mice from airway inflammation and lung function decline. DACH1 knockdown and overexpression promoted and inhibited IL-6 and IL-8 secretion, respectively, in 16HBE human bronchial epidermal cells after CS extract stimulation. NRF2 (nuclear factor erythroid 2-related factor 2) was discovered to be a novel downstream target of DACH1, which binds directly to its promoter. By activating NRF2 signaling, DACH1 induction reduced inflammation. DACH1 levels are lower in smokers and nonsmoking patients with COPD than in nonsmokers. DACH1 has protective effects against inflammation induced by CS by activating the NRF2 signaling pathway. Targeting DACH1 is a potentially viable therapeutic approach for COPD treatment.

Nrf-2 as a novel target in radiation induced lung injury

Radiation-induced lung injury (RILI) is a common and fatal complication of chest radiotherapy. The underlying mechanisms include radiation-induced oxidative stress caused by damage to the deoxyribonucleic acid (DNA) and production of reactive oxygen species (ROS), resulting in apoptosis of lung and endothelial cells and recruitment of inflammatory cells and myofibroblasts expressing NADPH oxidase to the site of injury, which in turn contribute to oxidative stress and cytokine production. Nuclear factor erythroid 2-related factor 2 (Nrf-2) is a vital transcription factor that regulates oxidative stress and inhibits inflammation. Studies have shown that Nrf-2 protects against radiation-induced lung inflammation and fibrosis. This review discusses the protective role of Nrf-2 in RILI and its possible mechanisms.

Cyclic Peptide Keap1-Nrf2 Protein-Protein Interaction Inhibitors: Design, Synthesis, and In Vivo Treatment of Acute Lung Injury

Directly blocking the Keap1-Nrf2 pathway is a promising strategy for the mitigation of acute lung injury (ALI). Peptide Keap1-Nrf2 inhibitors have been reported to have a high Keap1 binding affinity. However, these inhibitors showed weak activity in cells and/or animals. In this study, we designed a series of linear peptides from an Nrf2-based 9-mer Ac-LDEETGEFL-NH2. To improve the cellular activity, we further designed cyclic peptides based on the crystal complex of Keap1 with a linear peptide. Among them, cyclic 9-mer ZC9 targeting Keap1 showed a better affinity (KD2 = 51 nM). Specifically, it exhibited an acceptable water solubility (>38 mg/mL), better cell permeability, cell activity, and metabolic stability (serum t1/2 > 24 h). In the in vitro LPS-induced oxidative damages and ALI model, ZC9 showed significant dose-response reversal activity without apparent toxicity. In conclusion, our results suggested ZC9 as a lead cyclic peptide targeting the Keap1-Nrf2 pathway for ALI clinical treatment.

Optimization Efforts for Identification of Novel Highly Potent Keap1-Nrf2 Protein-Protein Interaction Inhibitors

In research focused on protein-protein interaction (PPI) inhibitors, the optimization process to achieve both high inhibitory activity and favorable physicochemical properties remains challenging. Our previous study reported the discovery of novel and bioavailable Keap1-Nrf2 PPI inhibitor 8 which exhibited moderate in vivo activity in rats. In this work, we present our subsequent efforts to optimize this compound. Two distinct approaches were employed, targeting high energy water molecules and Ser602 as "hot spots" from the anchor with good aqueous solubility, metabolic stability, and membrane permeability. Through ligand efficiency (LE)-guided exploration, we identified two novel inhibitors 22 and 33 with good pharmacokinetics (PK) profiles and more potent in vivo activities, which appear to be promising chemical probes among the existing inhibitors.

Targeting respiratory microbiomes in COPD and bronchiectasis

INTRODUCTION

This review summarizes our current understanding of the respiratory microbiome in COPD and Bronchiectasis. We explore the interplay between microbial communities, host immune responses, disease pathology, and treatment outcomes.

AREAS COVERED

We detail the dynamics of the airway microbiome, its influence on chronic respiratory diseases, and analytical challenges. Relevant articles from PubMed and Medline (January 2010-March 2024) were retrieved and summarized. We examine clinical correlations of the microbiome in COPD and bronchiectasis, assessing how current therapies impact upon it. The potential of emerging immunotherapies, antiinflammatories and antimicrobial strategies is discussed, with focus on the pivotal role of commensal taxa in maintaining respiratory health and the promising avenue of microbiome remodeling for disease management.

EXPERT OPINION

Given the heterogeneity in microbiome composition and its pivotal role in disease development and progression, a shift toward microbiome-directed therapeutics is appealing. This transition, from traditional 'pathogencentric' diagnostic and treatment modalities to those acknowledging the microbiome, can be enabled by evolving crossdisciplinary platforms which have the potential to accelerate microbiome-based interventions into routine clinical practice. Bridging the gap between comprehensive microbiome analysis and clinical application, however, remains challenging, necessitating continued innovation in research, diagnostics, trials, and therapeutic development pipelines.

Anti-inflammatory effect of Piper longum L. fruit methanolic extract on lipopolysaccharide-treated RAW 264.7 murine macrophages

Context

The Piper species was studied several potential properties such as anti-tumor, anti-inflammatory and antioxidant activity. However, the specific anti-inflammatory activity of the extract from the fruits of P. longum L. has not been investigated.

Objectives

Our study want to examine the anti-inflammatory effects of P. longum L. fruit methanolic extracts (PLE) on lipopolysachharide (LPS)-stimulated RAW 264.7 murine macrophages to understand the mechanism of this effect.

Method

This study examined the chemical profiling of PLE by LC-HRMS analysis and measured the presence of nitric oxide (NO), interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in the supernatant using the Griess reagent assay and enzyme-linked immunosorbent assay (ELISA), respectively. The mRNA expression of IL-6, TNF-α, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) were evaluated by using real-time quantitative polymerase chain reaction (RT-qPCR). Furthermore, the protein expression of COX-2, iNOS and the phosphorylation of MAPK family, c-Jun N-terminal kinase (JNK), p38 in protein level were observed by western blotting.

Result

PLE have detected 66 compounds which belong to different classes such as alkaloids, flavonoids, terpenoids, phenolics, lactones, and organic acids inhibited nitric oxide products with the IC50 = 28.5 ± 0.91 μg/mL. Moreover, PLE at 10-100 μg/mL up-regulate HO-1 protein expression from 3 to 10 folds at 3 h. It also downregulated the mRNA and protein expression of iNOS, COX-2, decreased IL-6 and TNF-α secretion by modulating the mitogen-activated protein kinase (MAPK) signaling pathway, specifically by decreasing the phosphorylation of p38 and JNK.

Conclusion

These results shown chemical profiling of PLE and demonstrated that PLE exhibits anti-inflammatory effects by regulating the MAPK family and could be a potential candidate for the treatment of inflammatory diseases.

Del-1 Plays a Protective Role against COPD Development by Inhibiting Inflammation and Apoptosis

Neutrophilic inflammation is a prominent feature of chronic obstructive pulmonary disease (COPD). Developmental endothelial locus-1 (Del-1) has been reported to limit excessive neutrophilic inflammation by inhibiting neutrophil adhesion to the vascular endothelial cells. However, the effects of Del-1 in COPD are not known. We investigated the role of Del-1 in the pathogenesis of COPD. Del-1 protein expression was decreased in the lungs of COPD patients, especially in epithelial cells and alveolar macrophages. In contrast to human lung tissue, Del-1 expression was upregulated in lung tissue from mice treated with cigarette smoke extracts (CSE). Overexpression of Del-1 significantly suppressed IL-8 release and apoptosis in CSE-treated epithelial cells. In contrast, knockdown of Del-1 enhanced IL-8 release and apoptosis. In macrophages, overexpression of Del-1 significantly suppressed inflammatory cytokine release, and knockdown of Del-1 enhanced it. This anti-inflammatory effect was mediated by inhibiting the phosphorylation and acetylation of NF-κB p65. Nuclear factor erythroid 2-related factor 2 (Nrf2) activators, such as quercetin, resveratrol, and sulforaphane, increased Del-1 in both cell types. These results suggest that Del-1, mediated by Nrf2, plays a protective role against the pathogenesis of COPD, at least in part through anti-inflammatory and anti-apoptotic effects.

Heavy metal levels and flavonoid intakes are associated with chronic obstructive pulmonary disease: an NHANES analysis (2007-2010 to 2017-2018)

BACKGROUND

The association between exposure to environmental metals and chronic obstructive pulmonary disease (COPD) is preventing chronic lung diseases. However, little is currently known about the interaction between heavy metals and flavonoids in relation to the risk of COPD. This study aims to bridge this knowledge gap by leveraging The National Health and Nutrition Examination Survey (NHANES) database to evaluate thecorrelation between blood levels of heavy metals (cadmium, lead, mercury) and the intake of various flavonoid compounds (isoflavones, anthocyanidins, flavan-3-ols, flavanones, flavones, flavonols, total flavonoids). Additionally, appropriate dietary recommendations are provided based on the study findings.

MATERIALS AND METHODS

Cross-sectional analysis was conducted using the 2007-2010 and 2017-2018 NHANES data. Specialized weighted complex survey design analysis software was used for data analysis. Multivariate logistic regression models and restricted cubic splines (RCS) were used to evaluate the relationship between blood heavy metal levels, flavonoids intake, and COPD incidence in all participants, and to explore the effect of different levels of flavonoids intake on COPD caused by heavy metal exposure.

RESULTS

A total of 7,265 adults aged ≥ 40 years were analyzed. Higher levels of blood cadmium (Cd), blood lead and Anthocyanidin (AC) intake were independently associated with an increased risk of COPD (Cd highest quantile vs. lowest: OR = 1.73, 95% CI, 1.25-2.3; Lead highest quantile vs. lowest quantile: OR = 1.44, 95% CI, 1.11-1.86; AC highest quantile vs. lowest: OR = 0.73, 95% CI, 0.54-0.99). When AC intake exceeded 11.56 mg/d, the effect of Cd exposure on COPD incidence decreased by 27%, and this finding was more significant in smokers.

CONCLUSION

Higher levels of Cd (≥ 0.45ug/L) and lead (≥ 0.172 ug/L) were positively correlated with the risk of COPD among participants aged 40 years and above, while AC intake (≥ 11.56 mg/d) could reduce the risk related to blood Cd.

Advances in the Use of N-Acetylcysteine in Chronic Respiratory Diseases

N-acetylcysteine (NAC) is widely used because of its mucolytic effects, taking part in the therapeutic protocols of cystic fibrosis. NAC is also administered as an antidote in acetaminophen (paracetamol) overdosing. Thanks to its wide antioxidative and anti-inflammatory effects, NAC may also be of benefit in other chronic inflammatory and fibrotizing respiratory diseases, such as chronic obstructive pulmonary disease, bronchial asthma, idiopathic lung fibrosis, or lung silicosis. In addition, NAC exerts low toxicity and rare adverse effects even in combination with other treatments, and it is cheap and easily accessible. This article brings a review of information on the mechanisms of inflammation and oxidative stress in selected chronic respiratory diseases and discusses the use of NAC in these disorders.

High-Frequency Repetitive Magnetic Stimulation Activates Bactericidal Activity of Macrophages via Modulation of p62/Keap1/Nrf2 and p38 MAPK Pathways

The effects of repetitive magnetic stimulation (rMS) have predominantly been studied in excitable cells, with limited research in non-excitable cells. This study aimed to investigate the impact of rMS on macrophages, which are crucial cells in the innate immune defense. THP-1-derived macrophages subjected to a 5 min session of 10 Hz rMS exhibited increased Nrf2 activation and decreased Keap1 expression. We found that activation of the Nrf2 signaling pathway relied on rMS-induced phosphorylation of p62. Notably, rMS reduced the intracellular survival of Staphylococcus aureus in macrophages. Silencing Nrf2 using siRNA in THP-1-derived macrophages or utilizing Nrf2 knockout in alveolar macrophages abolished this effect. Additionally, rMS attenuated the expression of IL-1β and TNF-α inflammatory genes by S. aureus and inhibited p38 MAPK activation. These findings highlight the capacity of rMS to activate the non-canonical Nrf2 pathway, modulate macrophage function, and enhance the host's defense against bacterial infection.

Nontoxic Levels of Se-Containing Compounds Increase Survival by Blocking Oxidative and Inflammatory Stresses via Signal Pathways Whereas High Levels of Se Induce Apoptosis

Selenium is a main group element and an essential trace element in human health. It was discovered in selenocysteine (SeC) by Stadtman in 1974. SeC is an encoded natural amino acid hailed as the 21st naturally occurring amino acid (U) present in several enzymes and which exquisitely participates in redox biology. As it turns out, selenium bears a U-shaped toxicity curve wherein too little of the nutrient present in biology leads to disorders; concentrations that are too great, on the other hand, pose toxicity to biological systems. In light of many excellent previous reviews and the corpus of literature, we wanted to offer this current review, in which we present aspects of the clinical and biological literature and justify why we should further investigate Se-containing species in biological and medicinal contexts, especially small molecule-containing species in biomedical research and clinical medicine. Of central interest is how selenium participates in biological signaling pathways. Several clinical medical cases are recounted; these reports are mainly pertinent to human cancer and changes in pathology and cases in which the patients are often terminal. Selenium was an option chosen in light of earlier chemotherapeutic treatment courses which lost their effectiveness. We describe apoptosis, and also ferroptosis, and senescence clearly in the context of selenium. Other contemporary issues in research also compelled us to form this review: issues with CoV-2 SARS infection which abound in the literature, and we described findings with human patients in this context. Laboratory scientific studies and clinical studies dealing with two main divisions of selenium, organic (e.g., methyl selenol) or inorganic selenium (e.g., sodium selenite), are discussed. The future seems bright with the research and clinical possibilities of selenium as a trace element, whose recent experimental clinical treatments have so far involved dosing simply and inexpensively over a set of days, amounts, and time intervals.

CEACAM6 as a Novel Therapeutic Target to Boost HO-1-mediated Antioxidant Defense in COPD

Rationale: Tobacco smoking and air pollution are primary causes of chronic obstructive pulmonary disease (COPD). However, only a minority of smokers develop COPD. The mechanisms underlying the defense against nitrosative/oxidative stress in nonsusceptible smokers to COPD remain largely unresolved. Objectives: To investigate the defense mechanisms against nitrosative/oxidative stress that possibly prevent COPD development or progression. Methods: Four cohorts were investigated: 1) sputum samples (healthy, n = 4; COPD, n = 37), 2) lung tissue samples (healthy, n = 13; smokers without COPD, n = 10; smoker+COPD, n = 17), 3) pulmonary lobectomy tissue samples (no/mild emphysema, n = 6), and 4) blood samples (healthy, n = 6; COPD, n = 18). We screened 3-nitrotyrosine (3-NT) levels, as indication of nitrosative/oxidative stress, in human samples. We established a novel in vitro model of a cigarette smoke extract (CSE)-resistant cell line and studied 3-NT formation, antioxidant capacity, and transcriptomic profiles. Results were validated in lung tissue, isolated primary cells, and an ex vivo model using adeno-associated virus-mediated gene transduction and human precision-cut lung slices. Measurements and Main Results: 3-NT levels correlate with COPD severity of patients. In CSE-resistant cells, nitrosative/oxidative stress upon CSE treatment was attenuated, paralleled by profound upregulation of heme oxygenase-1 (HO-1). We identified carcinoembryonic antigen cell adhesion molecule 6 (CEACAM6) as a negative regulator of HO-1-mediated nitrosative/oxidative stress defense in human alveolar type 2 epithelial cells (hAEC2s). Consistently, inhibition of HO-1 activity in hAEC2s increased the susceptibility toward CSE-induced damage. Epithelium-specific CEACAM6 overexpression increased nitrosative/oxidative stress and cell death in human precision-cut lung slices on CSE treatment. Conclusions: CEACAM6 expression determines the hAEC2 sensitivity to nitrosative/oxidative stress triggering emphysema development/progression in susceptible smokers.

Sensitization of GSH synthesis by curcumin curtails acrolein-induced alveolar epithelial apoptosis via Keap1 cysteine conjugation: A randomized controlled trial and experimental animal model of pneumonitis

INTRODUCTION

Epidemiological studies have reported an association between exposures to ambient air pollution and respiratory diseases, including chronic obstructive pulmonary disease (COPD). Pneumonitis is a critical driving factor of COPD and exposure to air pollutants (e.g., acrolein) is associated with increased incidence of pneumonitis.

OBJECTIVES

Currently available anti-inflammatory therapies provide little benefit against respiratory diseases. To this end, we investigated the preventive role of curcumin against air pollutant-associated pneumonitis and its underlying mechanism.

METHODS

A total of 40 subjects was recruited from Chengdu, China which is among the top three cities in terms of respiratory mortality related to air pollution. The participants were randomly provided either placebo or curcumin supplements for 2 weeks and blood samples were collected at the baseline and at the end of the intervention to monitor systemic markers. In our follow up mechanistic study, C57BL/6 mice (n = 40) were randomly allocated into 4 groups: Control group (saline + no acrolein), Curcumin only group (curcumin + no acrolein), Acrolein only group (saline + acrolein), and Acrolein + Curcumin group (curcumin + acrolein). Curcumin was orally administered at 100 mg/kg body weight once a day for 10 days, and then the mice were subjected to nasal instillation of acrolein (5 mg/kg body weight). Twelve hours after single acrolein exposure, all mice were euthanized.

RESULTS

Curcumin supplementation, with no noticeable adverse responses, reduced circulating pro-inflammatory cytokines in association with clinical pneumonitis as positive predictive while improving those of anti-inflammatory cytokines. In the pre-clinical study, curcumin reduced pneumonitis manifestations by suppression of intrinsic and extrinsic apoptotic signaling, which is attributed to enhanced redox sensing of Nrf2 and thus sensitized synthesis and restoration of GSH, at least in part, through curcumin-Keap1 conjugation.

CONCLUSIONS

Our study collectively suggests that curcumin could provide an effective preventive measure against air pollutant-enhanced pneumonitis and thus COPD.

Astaxanthin attenuates cigarette smoking-induced oxidative stress and inflammation in a sirtuin 1-dependent manner

Oxidative stress and chronic inflammation play key roles in the pathogenesis of chronic obstructive pulmonary disease (COPD). Astaxanthin (AXT) is a keto-carotenoid with a variety of biological functions, including antioxidant and anti-inflammatory effects This study aimed to explore the protective role and underlying mechanism of AXT in the pathogenesis of COPD. In this study, we found AXT alleviated pulmonary emphysema in a CS-exposed mouse model and regulated the expression of MMP-9/TIMP-1. And, AXT attenuates CSE-induced small airway fibrosis. Meanwhile, AXT inhibited Nrf2-modulated oxidative stress and the p65 NF-κB-regulated inflammatory pathway in both the mouse model and CSE-treated HBE cells. Mechanistically, AXT could directly bind to SIRT1 (the binding energy of the complex was -8.8 kcal/mol) and regulate the deacetylation activity of SIRT1. Finally, by activating SIRT1 deacetylation, AXT deacetylated Nrf2 and contributed to its action of reducing oxidative stress by generating antioxidant enzymes, and inhibiting p65 NF-κB transcriptional activity to suppress the inflammatory response. Our results show that treatment with AXT significantly reverses the oxidative stress and inflammation induced by cigarette smoke both in vivo and in vitro in a sirtuin 1-dependent manner.

Green tea extract ameliorates macrophage-driven emphysematous lesions in chronic obstructive pulmonary disease induced by cigarette smoke condensate

Chronic obstructive pulmonary disease (COPD) is an important lung disease characterized by complicated symptoms including emphysema. We aimed to explore the mechanisms underlying the protective effect of green tea extract (GTE) on cigarette smoke condensate (CSC)-induced emphysema by demonstrating the reduction of macrophage-induced protease expression through GTE treatment in vivo and in vitro. Mice were intranasally administered 50 mg/kg CSC once a week for 4 weeks, and doses of 100 or 300 mg/kg GTE were administered orally once daily for 4 weeks. GTE significantly reduced macrophage counts in bronchoalveolar lavage fluid and emphysematous lesions in lung tissues in CSC-exposed mice. In addition, GTE suppressed CSC-induced extracellular signal-regulated kinase (ERK)/activator protein (AP)-1 phosphorylation followed by matrix metalloproteinases (MMP)-9 expression as revealed by western blotting, immunohistochemistry, and zymography in CSC-instilled mice. These underlying mechanisms related to reduced protease expression were confirmed in NCI-H292 cells stimulated by CSC. Taken together, GTE effectively inhibits macrophage-driven emphysematous lesions induced by CSC treatment, and these protective effects of GTE are closely related to the ERK/AP-1 signaling pathway, followed by a reduced protease/antiprotease imbalance. These results suggest that GTE can be used as a supplementary agent for the prevention of emphysema progression in COPD patients.

Dental Pulp Stem Cells Ameliorate Elastase-Induced Pulmonary Emphysema by Regulating Inflammation and Oxidative Stress

Background

Dental pulp stem cells (DPSCs) are considered excellent candidates for stem cell-based tissue regeneration. In this study, we aimed to evaluate the therapeutic effect of DPSCs in a mouse chronic obstructive pulmonary disease (COPD) model and to explore whether DPSCs reduce lung inflammation and oxidative stress by regulating the nuclear factor erythroid-2 related factor-2 (Nrf2) signaling pathway.

Methods

DPSCs were isolated from dental pulp tissue by the tissue block method. Emphysema of C57BL/6 mice was induced by endotracheal administration of porcine pancreatic elastase (PPE). Then, the DPSCs were injected into the lungs through the trachea, and after 3 weeks of stem cell treatment, various efficacy tests were performed. The AniRes2005 animal lung function analytic system was used to detect lung function. Hematoxylin-eosin staining (H&E) and Victoria blue staining was used to assess emphysema severity. The animal tissues were detected by Western blot, RT‒qPCR, ELISA and oxidative stress related detection.

Results

In experimental COPD models, DPSCs transplantation improved lung function, body weight, and emphysema-like changes better than bone marrow mesenchyml stem cells (BM-MSCs). Compared with the COPD group, the levels of IL-1β, TNF-α and IL-6 in lung tissue and bronchoalveolar lavage fluid (BALF) were decreased after transplantation of DPSCs. DPSCs may be associated with lower malondialdehyde (MDA) levels, and higher catalase (CAT) and glutathione (GSH) levels. Western blot results showed that the expression of Nrf2 and its downstream factors increased after transplantation of DPSCs.

Conclusion

The current study showed that DPSCs had good performance in the treatment of a mouse COPD model and could be a promising option for stem cell therapy. DPSCs may play antioxidant and anti-inflammatory roles in COPD by activating the Nrf2 signaling pathway.

YPL-001 Shows Various Beneficial Effects against Cigarette Smoke Extract-Induced Emphysema Formation: Anti-Inflammatory, Anti-Oxidative, and Anti-Apoptotic Effects

Inflammation, oxidative stress, and apoptosis are thought to be important causes of chronic obstructive pulmonary disease (COPD). We investigated the effect of YPL-001 (under phase 2a study, ClinicalTrials.gov identifier NCT02272634), a drug derived from Pseudolysimachion rotundum var. subintegrum, on cigarette smoke extract (CSE)-induced inflammation, the anti-oxidative pathway, and apoptosis in human lung epithelial cells and on CSE-induced emphysema in mice. YPL-001 suppressed CSE-induced expression of IL8 mRNA and protein. This was due to the reduction in NF-κB transcriptional activity by YPL-001, which resulted from the blockade of acetylation of the NF-κB subunit p65 (Lys310). Histone deacetylases (HDACs) prevent gene transcription by condensing the DNA structure and affecting NF-κB nuclear binding. YPL-001 alone increased HDAC2 activity and enhanced CSE-induced activation of HDAC2. YPL-001-induced suppression of NF-κB transcriptional activity might be caused by increased HDAC2 activity. YPL-001 increased nuclear factor (erythroid-derived 2)-like 2 (Nrf2) expression via both degradation of its inhibitory protein, Kelch-like ECH-associated protein 1, and an increase in de novo protein synthesis. YPL-001 increased the DNA binding activity of Nrf2. Consequently, YPL-001 upregulated the expression of Nrf2-targeted anti-oxidant genes such as NAD(P)H quinone dehydrogenase 1 and heme oxygenase 1. Moreover, YPL-001 significantly suppressed CSE-induced apoptotic cell death. In vivo study showed that CSE-induced emphysematous changes, neutrophilic inflammation, protein leakage into bronchoalveolar space, and lung cell apoptosis in mice were suppressed by YPL-001 treatment. Taken together, these results suggest that YPL-001 is a good therapeutic candidate for the treatment of COPD by blocking inflammation and apoptosis and activating the anti-oxidative pathway.

Metabolism-Related Gene TXNRD1 Regulates Inflammation and Oxidative Stress Induced by Cigarette Smoke through the Nrf2/HO-1 Pathway in the Small Airway Epithelium

Chronic obstructive pulmonary disease (COPD), a small airway disease, is regarded as a metabolic disorder. To further uncover the metabolic profile of COPD patients, it is necessary to identify metabolism-related differential genes in small airway epithelium (SAE) of COPD. Metabolism-related differential genes in SAE between COPD patients and nonsmokers were screened from GSE128708 and GSE20257 datasets. KEGG, GO, and PPI analyses were performed to evaluate the pathway enrichment, term enrichment, and protein interaction of candidate metabolism-related differential genes, respectively. RT-PCR was used to verify the mRNA expression of the top ten differential genes. Western blotting was used to evaluate the protein expression of TXNRD1. TXNRD1 inhibitor auranofin (AUR) was used to assess the impact of TXNRD1 on oxidative stress and inflammation induced by cigarette smoke extraction (CSE). Twenty-four metabolism-related differential genes were selected. ALDH3A1, AKR1C3, CYP1A1, AKC1C1, CPY1B1, and TXNRD1 in the top ten genes were significantly upregulated after CSE simulation for 24 h in human bronchial epithelial (16HBE) cells. Among them, CYP1A1 and TXNRD1 also have a significant upregulation in primary SAE after simulation of CSE for 24 h. The overexpression of protein TXNRD1 has also been detected in 16HBE cells, primary SAE stimulated with CSE, and mouse lung exposed to cigarette smoke (CS). Additionally, inhibition of TXNRD1 with 0.1 μM AUR alleviated the expression of IL-6 and reactive oxygen species (ROS) induced by CSE by activating the Nrf2/HO-1 pathway in 16HBE cells. This study identified twenty-four metabolism-related differential genes associated with COPD. TXNRD1 might participate in the oxidative stress and inflammation induced by CS by regulating the activation of the Nrf2/HO-1 pathway.

Modulation of mouse laryngeal inflammatory and immune cell responses by low and high doses of mainstream cigarette smoke

Cigarette smoking is a major risk factor for laryngeal diseases. Despite well-documented cigarette smoke (CS) induced laryngeal histopathological changes, the underlying immunopathological mechanisms remain largely unexplored. The goal of this study was to evaluate inflammatory and immune cell responses in a CS-exposed larynx. Specifically, we used a 4-week subacute whole-body CS inhalation mouse model to assess these responses in the laryngeal mucosa upon exposure to low (LD; 1 h/day) and high dose (HD; 4 h/day) CS. Laryngeal tissues were harvested and evaluated using a 254-plex NanoString inflammation panel and neutrophil/macrophage/T-cell immunohistochemistry (IHC). NanoString global and differential gene expression analysis revealed a unique expression profile only in the HD group, with 26 significant differentially expressed genes (DEGs). StringDB KEGG pathway enrichment analysis revealed the involvement of these DEGs with pro-inflammatory pathways including TNF/TNFα and IL-17. Furthermore, inflammatory responses remained inhibited in conjunction with predicted activated states of anti-inflammatory regulators like PPARγ and NFE2L2 upon Ingenuity Pathway Analysis (IPA). Subglottic T-cell levels remained significantly inhibited as corroborated by IPA predictions. Overall, our key findings are consistent with HD exposures being anti-inflammatory and immunosuppressive. Furthermore, the identification of important regulatory genes and enriched pathways may help improve clinical interventions for CS-induced laryngeal diseases.

Gold Nanoparticles Inhibit Steroid-Insensitive Asthma in Mice Preserving Histone Deacetylase 2 and NRF2 Pathways

Background: Gold nanoparticles (AuNPs) can inhibit pivotal pathological changes in experimental asthma, but their effect on steroid-insensitive asthma is unclear. The current study assessed the effectiveness of nebulized AuNPs in a murine model of glucocorticoid (GC)-resistant asthma. Methods: A/J mice were sensitized and subjected to intranasal instillations of ovalbumin (OVA) once a week for nine weeks. Two weeks after starting allergen stimulations, mice were subjected to Budesonide or AuNP nebulization 1 h before stimuli. Analyses were carried out 24 h after the last provocation. Results: We found that mice challenged with OVA had airway hyperreactivity, eosinophil, and neutrophil infiltrates in the lung, concomitantly with peribronchiolar fibrosis, mucus production, and pro-inflammatory cytokine generation compared to sham-challenged mice. These changes were inhibited in mice treated with AuNPs, but not Budesonide. In the GC-resistant asthmatic mice, oxidative stress was established, marked by a reduction in nuclear factor erythroid 2-related factor 2 (NRF2) levels and catalase activity, accompanied by elevated values of thiobarbituric acid reactive substances (TBARS), phosphoinositide 3-kinases δ (PI3Kδ) expression, as well as a reduction in the nuclear expression of histone deacetylase 2 (HDAC2) in the lung tissue, all of which sensitive to AuNPs but not Budesonide treatment. Conclusion: These findings suggest that AuNPs can improve GC-insensitive asthma by preserving HDAC2 and NRF2.

Flavonoid intakes inversely associate with COPD in smokers

INTRODUCTION

Higher flavonoid intakes are beneficially associated with pulmonary function parameters; however, their association with chronic obstructive pulmonary disease (COPD) is unknown. This study aimed to examine associations between intakes of 1) total flavonoids, 2) flavonoid subclasses and 3) major flavonoid compounds with incident COPD in participants from the Danish Diet, Cancer and Health study.

METHODS

This prospective cohort included 55 413 men and women without COPD, aged 50-65 years at recruitment. Habitual flavonoid intakes at baseline were estimated from a food frequency questionnaire using Phenol-Explorer. Danish nationwide registers were used to identify incident cases of COPD. Associations were modelled using restricted cubic splines within Cox proportional hazards models.

RESULTS

During 23 years of follow-up, 5557 participants were diagnosed with COPD. Of these, 4013 were current smokers, 1062 were former smokers and 482 were never-smokers. After multivariable adjustments, participants with the highest total flavonoid intakes had a 20% lower risk of COPD than those with the lowest intakes (quintile 5 versus quintile 1: HR 0.80, 95% CI 0.74-0.87); a 6-22% lower risk was observed for each flavonoid subclass. The inverse association between total flavonoid intake and COPD was present in both men and women but only in current smokers (HR 0.77, 95% CI 0.70-0.84) and former smokers (HR 0.82, 95% CI 0.69-0.97), not never-smokers. Furthermore, higher flavonoid intakes appeared to lessen, but not negate, the higher risk of COPD associated with smoking intensity.

CONCLUSION

Dietary flavonoids may be important for partially mitigating the risk of smoking-related COPD. However, smoking cessation should remain the highest priority.

Longevity-Promoting Pathways and Transcription Factors Respond to and Control Extracellular Matrix Dynamics During Aging and Disease

Aging is one of the largest risk factors for cancer, type 2 diabetes, osteoarthritis, cardiovascular diseases, and other age-related pathologies. Here, we give a detailed description of the interplay of chronic age-related pathologies with the remodeling of the extracellular matrix during disease development and progression. Longevity-promoting signaling pathways slow or prevent age-related diseases. In particular, we focus on the mTOR signaling pathway, sirtuins, and canonical longevity-promoting transcription factors, such as FOXO, NF-κB, and Nrf2. We extend our analysis using chromatin immunoprecipitation (ChIP) sequencing and transcriptomic data and report that many established and emerging longevity-promoting transcription factors, such as CREB1, FOXO1,3, GATA1,2,3,4, HIF1A, JUN, KLF4, MYC, NFE2L2/Nrf2, RELA/NF-κB, REST, STAT3,5A, and TP53/p53, directly regulate many extracellular matrix genes and remodelers. We propose that modulation of these pathways increases lifespan and protects from age-related diseases in part due to their effects on extracellular matrix remodeling. Therefore, to successfully treat age-related diseases, it is necessary to better understand the connection between extracellular matrix components and longevity pathways.

Structure-activity relationships of 1,4-bis(arylsulfonamido)-benzene or naphthalene-N,N'-diacetic acids with varying C2-substituents as inhibitors of Keap1-Nrf2 protein-protein interaction

The Keap1-Nrf2-ARE pathway plays an important role in responding to oxidative stress and maintaining the redox homeostasis. Small molecule inhibitors targeting directly the Keap1-Nrf2 protein-protein interaction (PPI) can potentially be developed into effective preventive and therapeutic agents for numerous chronic inflammatory diseases. To improve the drug-like properties and inhibitory potency of these inhibitors, a series of 1,4-bis(arylsulfonamido)benzene or naphthalene-N,N'-diacetic acids with varying substituents at C-2 position of the benzene or naphthalene core were designed and synthesized. Among them, compound 12d with 2-(4-fluorobenzyloxy) group was the most potent direct inhibitor of Keap1-Nrf2 PPI with an IC₅₀ of 64.5 nM in the fluorescent polarization (FP) assay and 14.2 nM in a time-resolved fluorescence resonance energy transfer (TR-FRET) assay. Moreover, cell-based biological assay showed that 12d significantly increased the mRNA levels of Nrf2 downstream genes, GSTM3, HMOX2 and NQO1, through Nrf2 activation. The discovery of the new scaffolds possessing diverse O-linked fragments at the C2 position offers opportunities to further modify the chemical structures of Keap1-Nrf2 PPI inhibitors to improve their pharmacokinetic, efficacy and safety profiles.

Mechanistic Understanding of Lung Inflammation: Recent Advances and Emerging Techniques

Acute respiratory distress syndrome (ARDS) is a life-threatening lung injury characterized by an acute inflammatory response in the lung parenchyma. Hence, it is considered as the most appropriate clinical syndrome to study pathogenic mechanisms of lung inflammation. ARDS is associated with increased morbidity and mortality in the intensive care unit (ICU), while no effective pharmacological treatment exists. It is very important therefore to fully characterize the underlying pathobiology and the related mechanisms, in order to develop novel therapeutic approaches. In vivo and in vitro models are important pre-clinical tools in biological and medical research in the mechanistic and pathological understanding of the majority of diseases. In this review, we will present data from selected experimental models of lung injury/acute lung inflammation, which have been based on clinical disorders that can lead to the development of ARDS and related inflammatory lung processes in humans, including ventilation-induced lung injury (VILI), sepsis, ischemia/reperfusion, smoke, acid aspiration, radiation, transfusion-related acute lung injury (TRALI), influenza, Streptococcus (S.) pneumoniae and coronaviruses infection. Data from the corresponding clinical conditions will also be presented. The mechanisms related to lung inflammation that will be covered are oxidative stress, neutrophil extracellular traps, mitogen-activated protein kinase (MAPK) pathways, surfactant, and water and ion channels. Finally, we will present a brief overview of emerging techniques in the field of omics research that have been applied to ARDS research, encompassing genomics, transcriptomics, proteomics, and metabolomics, which may recognize factors to help stratify ICU patients at risk, predict their prognosis, and possibly, serve as more specific therapeutic targets.

COPD lung studies of Nrf2 expression and the effects of Nrf2 activators

BACKGROUND

Nrf2 regulates cellular antioxidant defence in lung cells, including epithelial cells and alveolar macrophages (AM). The Nrf2/Keap-1 pathway can be modulated by activators with different modes of action; electrophilic compounds and protein-protein interaction (PPI) inhibitors. We assessed Nrf2 and Keap-1 protein and gene levels in COPD compared to controls and the effect of Nrf2 activators on COPD AM.

METHODS

Lung resected tissue from non-smokers, smokers and COPD patients were analysed for epithelial and AM expression of Nrf2 and Keap-1 by imunoshistochemistry and by qPCR in isolated AM. AM were cultured with Nrf2 activators CDDO, C4X_6665, GSK7, MMF and Sulforaphane. Expression of Nrf2 target genes NQO1, HMOX1 SOD1 and TXNRD1 and NQO1 activity were assessed.

RESULTS

Nrf2 and Keap-1 expression was not altered in the epithelium or AM of COPD patients compared to controls. NQO1 activity was downregulated, while NQO1, HMOX1, SOD1 and TXNRD1 gene expression increased in COPD patients. All Nrf2 activators increased NQO1 activity, and NQO1, HMOX1, SOD1 and TXNRD1 expression in AMs from both COPD and smokers. The potency of C4X_6665 on NQO1 activity and regulation of Nrf2 target gene expression was higher than other compounds.

CONCLUSION

There is evidence of dysregulation of the Nrf2 signalling pathway in AM from COPD patients. The higher potency of the novel PPI Nrf2 compound C4X_6665 for inducing antioxidant activity and gene expression compared to electrophilic and other PPI Nrf2 activators highlights the therapeutic potential of this compound to address Nrf2 pathway dysregulation in COPD AM.

Dexmedetomidine Attenuates LPS-Induced Acute Lung Injury in Rats by Activating the Nrf2/ARE Pathway

Background

To investigate the effect of dexmedetomidine (Dex) on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats and its mechanism.

Methods

Eighteen SD rats were randomly divided into 3 groups (6 rats in each group): control group (intratracheal instillation of saline), ALI group (intratracheal instillation of 5 mg/kg LPS), and ALI-Dex group (tail vein injection of 50 μg/kg/h Dex + intratracheal instillation of LPS). Subsequently, the water content of lung tissues was assessed using the wet-dry (W/D) ratio and the histopathological changes of lung tissues using H&E staining. Further activities of ROS, SOD, and GSH-Px in lung tissues of rats were measured by an automatic biochemistry analyzer. ELISA was performed to detect TNF-α, IL-1β, and IL-6 expression in alveolar lavage fluid (BALF) and Western blot to detect the expression of Nrf2/ARE pathway-related proteins.

Results

After Dex treatment, a reduction in water content in lung tissue and an improvement of lung injury were found in the ALI rats. Compared with the ALI group, rats in the ALI-Dex group had decreased ROS activity and increased activities of SOD and GSH-Px in lung tissues. Dex-treated rats were also associated with a decrease in TNF-α, IL-1β, and IL-6 expression in alveolar lavage fluid (BALF). Additionally, increased expression levels of HO-1 and NQO1 in lung tissues and elevated expression of Nrf2 in the nucleus were shown in the ALI-Dex group compared with the ALI group.

Conclusion

Dex alleviates LPS-induced ALI by activating the Nrf2/ARE signaling pathway.

Role of nuclear factor erythroid 2-related factor 2 in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation due to chronic airway inflammation and destruction of the alveolar structure from persistent exposure to oxidative stress. The body has various antioxidant mechanisms for efficiently coping with such oxidative stress. The nuclear factor erythroid 2-related factor 2 (Nrf2)–antioxidant response element (ARE) is a representative system. Dysregulation of the Nrf2-ARE pathway is responsible for the development and promotion of COPD. Furthermore, COPD severity is also closely related to this pathway. There has been a clinical impetus to use Nrf2 for diagnostic and therapeutic purposes. Therefore, in this work, we systematically reviewed the clinical significance of Nrf2 in COPD patients, and discuss the value of Nrf2 as a potential COPD biomarker.

Mitochondria Related Cell Death Modalities and Disease

Mitochondria are well known as the centre of energy metabolism in eukaryotic cells. However, they can not only generate ATP through the tricarboxylic acid cycle and oxidative phosphorylation but also control the mode of cell death through various mechanisms, especially regulated cell death (RCD), such as apoptosis, mitophagy, NETosis, pyroptosis, necroptosis, entosis, parthanatos, ferroptosis, alkaliptosis, autosis, clockophagy and oxeiptosis. These mitochondria-associated modes of cell death can lead to a variety of diseases. During cell growth, these modes of cell death are programmed, meaning that they can be induced or predicted. Mitochondria-based treatments have been shown to be effective in many trials. Therefore, mitochondria have great potential for the treatment of many diseases. In this review, we discuss how mitochondria are involved in modes of cell death, as well as basic research and the latest clinical progress in related fields. We also detail a variety of organ system diseases related to mitochondria, including nervous system diseases, cardiovascular diseases, digestive system diseases, respiratory diseases, endocrine diseases, urinary system diseases and cancer. We highlight the role that mitochondria play in these diseases and suggest possible therapeutic directions as well as pressing issues that need to be addressed today. Because of the key role of mitochondria in cell death, a comprehensive understanding of mitochondria can help provide more effective strategies for clinical treatment.

Sulforaphane-Dependent Up-Regulation of NRF2 Activity Alleviates Both Systemic Inflammatory Response and Lung Injury After Hemorrhagic Shock/Resuscitation in Mice

ABSTRACT

Hemorrhagic shock/resuscitation (HS/R) is closely associated with overwhelming oxidative stress and systemic inflammation. As an effective activator of the nuclear factor-erythroid factor 2 related factor 2 (Nrf2) pathway, sulforaphane (SFN) exerts antioxidant and anti-inflammatory effects. We explored SFN's effects on alveolar macrophages (AMs), systemic inflammation, and pulmonary damage in an isolated murine HS/R model. Male C57/BL6 wild type and transgenic antioxidant response element (ARE)-luciferase (luc) mice (both n = 6 per group) were exposed to either pressure-controlled HS/R (mean arterial pressure 35-45 mm Hg for 90 min) or sham procedure (surgery without HS/R) or were sacrificed without intervention (control group). Fluid resuscitation was performed via the reinfusion of withdrawn blood and 0.9% saline. Sulforaphane or 0.9% saline (vehicle) was administrated intraperitoneally. Mice were sacrificed 6, 24, or 72 h after resuscitation. Bioluminescence imaging of ARE-luc mice was conducted to measure pulmonary Nrf2 activity. Plasma was collected to determine systemic cytokine levels. Alveolar macrophages were isolated before measuring cytokines in the supernatant and performing immunofluorescence staining, as well as Western blot for intracellular Nrf2. Histological damage was assessed via the acute lung injury score and wet/dry ratio.Hemorrhagic shock/resuscitation was associated with pulmonary Nrf2 activation. Sulforaphane enhanced pulmonary Nrf2 activity and the Nrf2 activation of AM, while it decreased lung damage. Sulforaphane exerted down-regulatory effects on AM-generated and systemic pro-inflammatory mediators, while it did not have such effects on IL-10.In conclusion, SFN beneficially enhances pulmonary Nrf2 activity and promotes Nrf2 accumulation in AMs' nuclei. This may exert not only local protective effects but also systemic effects via the down-regulation of pro-inflammatory cytokines. The administration of Nrf2 activator post-HS/R may represent an innovative treatment strategy.

Large-scale plasma proteomics can reveal distinct endotypes in chronic obstructive pulmonary disease and severe asthma

BACKGROUND

Chronic airway diseases including chronic obstructive pulmonary disease (COPD) and asthma are heterogenous in nature and endotypes within are underpinned by complex biology. This study aimed to investigate the utility of proteomic profiling of plasma combined with bioinformatic mining, and to define molecular endotypes and expand our knowledge of the underlying biology in chronic respiratory diseases.

METHODS

The plasma proteome was evaluated using an aptamer-based affinity proteomics platform (SOMAscan®), representing 1238 proteins in 34 subjects with stable COPD and 51 subjects with stable but severe asthma. For each disease, we evaluated a range of clinical/demographic characteristics including bronchodilator reversibility, blood eosinophilia levels, and smoking history. We applied modified bioinformatic approaches used in the evaluation of RNA transcriptomics.

RESULTS

Subjects with COPD and severe asthma were distinguished from each other by 365 different protein abundancies, with differential pathway networks and upstream modulators. Furthermore, molecular endotypes within each disease could be defined. The protein groups that defined these endotypes had both known and novel biology including groups significantly enriched in exosomal markers derived from immune/inflammatory cells. Finally, we observed associations to clinical characteristics that previously have been under-explored.

CONCLUSION

This investigational study evaluating the plasma proteome in clinically-phenotyped subjects with chronic airway diseases provides support that such a method can be used to define molecular endotypes and pathobiological mechanisms that underpins these endotypes. It provided new concepts about the complexity of molecular pathways that define these diseases. In the longer term, such information will help to refine treatment options for defined groups.

Alveolar macrophages: novel therapeutic targets for respiratory diseases

Alveolar macrophages (AMs) are lung-resident myeloid cells that sit at the interface of the airway and lung tissue. Under homeostatic conditions, their primary function is to clear debris, dead cells and excess surfactant from the airways. They also serve as innate pulmonary sentinels for respiratory pathogens and environmental airborne particles and as regulators of pulmonary inflammation. However, they have not typically been viewed as primary therapeutic targets for respiratory diseases. Here, we discuss the role of AMs in various lung diseases, explore the potential therapeutic strategies to target these innate cells and weigh the potential risks and challenges of such therapies. Additionally, in the context of the COVID-19 pandemic, we examine the role AMs play in severe disease and the therapeutic strategies that have been harnessed to modulate their function and protect against severe lung damage. There are many novel approaches in development to target AMs, such as inhaled antibiotics, liposomal and microparticle delivery systems, and host-directed therapies, which have the potential to provide critical treatment to patients suffering from severe respiratory diseases, yet there is still much work to be done to fully understand the possible benefits and risks of such approaches.

Bitter Gourd Honey Ameliorates Hepatic and Renal Diabetic Complications on Type 2 Diabetes Rat Models by Antioxidant, Anti-Inflammatory, and Anti-Apoptotic Mechanisms

Honey has several pharmacological effects, including anti-diabetic activity. However, the effectiveness of bitter gourd honey (BGH) in the treatment of diabetes mellitus (DM) is unknown. The aim of this study was to determine the antioxidant, anti-inflammatory, and anti-apoptotic properties of BGH on the kidney and liver of a streptozotocin-induced diabetes rat model.

METHODS

A single dose (nicotinamide 110 mg/kg, streptozotocin (STZ) 55 mg/kg, intraperitoneal (i.p.)) was used to induce DM in male rats. For 28 days, normal or diabetic rats were administered 1 g/kg/day and 2 g/kg/day of BGH orally. After the treatment, blood, liver, and kidney samples were collected and analysed for biochemical, histological, and molecular parameters. In addition, liquid chromatography-mass spectrometry (LC-MS) was used to identify the major bioactive components in BGH.

RESULTS

The administration of BGH to diabetic rats resulted in significant reductions in alanine transaminase (ALT),aspartate aminotransferase (AST), creatinine, and urea levels. Diabetic rats treated with BGH showed lesser pathophysiological alterations in the liver and kidney as compared to non-treated control rats. BGH-treated diabetic rats exhibited reduced levels of oxidative stress (MDA levels), inflammatory (MYD88, NFKB, p-NFKB, IKKβ), and apoptotic (caspase-3) markers, as well as higher levels of antioxidant enzymes (SOD, CAT, and GPx) in the liver and kidney. BGH contains many bioactive compounds that may have antioxidative stress, anti-inflammatory, and anti-apoptotic effects.

CONCLUSION

BGH protected the liver and kidney in diabetic rats by reducing oxidative stress, inflammation, and apoptosis-induced damage. As a result, BGH can be used as a potential therapy to ameliorate diabetic complications.

Fragment-Guided Discovery of Pyrazole Carboxylic Acid Inhibitors of the Kelch-like ECH-Associated Protein 1: Nuclear Factor Erythroid 2 Related Factor 2 (KEAP1:NRF2) Protein-Protein Interaction

The NRF2-mediated cytoprotective response is central to cellular homoeostasis, and there is increasing interest in developing small-molecule activators of this pathway as therapeutics for diseases involving chronic oxidative stress. The protein KEAP1, which regulates NRF2, is a key point for pharmacological intervention, and we recently described the use of fragment-based drug discovery to develop a tool compound that directly disrupts the protein-protein interaction between NRF2 and KEAP1. We now present the identification of a second, chemically distinct series of KEAP1 inhibitors, which provided an alternative chemotype for lead optimization. Pharmacophoric information from our original fragment screen was used to identify new hit matter through database searching and to evolve this into a new lead with high target affinity and cell-based activity. We highlight how knowledge obtained from fragment-based approaches can be used to focus additional screening campaigns in order to de-risk projects through the rapid identification of novel chemical series.

Modulation of cigarette smoke extract-induced human bronchial epithelial damage by eucalyptol and curcumin

Smoking is one of the most important leading death cause worldwide. From a toxicological perspective, cigarette smoke serves hazards especially for the human being exposed to passive smoke. Over the last decades, the effects of natural compounds on smoking-mediated respiratory diseases such as COPD, asthma, and lung cancer have been under investigation, as well as the mechanistic aspects of disease progression. In the present study, the protective mechanism of eucalyptol (EUC), curcumin (CUR), and their combination on BEAS-2B cells were investigated in vitro to understand their impact on cell death, oxidative cell injury, and inflammatory response induced by 3R4F reference cigarette extract (CSE). According to the present findings, EUC, CUR, and their combination improved cell viability, attenuated CSE-induced apoptosis, and LC3B expression. Further, CSE-induced oxidative damage and inflammatory response in human bronchial epithelial cells were remarkably reduced by the combination treatment through modification of enzymatic antioxidant activity, GSH, MDA, and intracellular ROS levels as well as nitrite and IL-6 levels. In addition, nuclear translocation of Nrf2, a regulatory protein involved in the indirect antioxidant response, was remarkably up-regulated with the combination pre-treatment. In conclusion, EUC and CUR in combination might be a potential therapeutic against smoking-induced lung diseases through antioxidant and inflammatory pathways and results represent valuable background for future in vivo pulmonary toxicity studies.

An Update on the Role of Nrf2 in Respiratory Disease: Molecular Mechanisms and Therapeutic Approaches

Nuclear factor erythroid 2-related factor (Nrf2) is a transcriptional activator of the cell protection gene that binds to the antioxidant response element (ARE). Therefore, Nrf2 protects cells and tissues from oxidative stress. Normally, Kelch-like ECH-associated protein 1 (Keap1) inhibits the activation of Nrf2 by binding to Nrf2 and contributes to Nrf2 break down by ubiquitin proteasomes. In moderate oxidative stress, Keap1 is inhibited, allowing Nrf2 to be translocated to the nucleus, which acts as an antioxidant. However, under unusually severe oxidative stress, the Keap1-Nrf2 mechanism becomes disrupted and results in cell and tissue damage. Oxide-containing atmospheric environment generally contributes to the development of respiratory diseases, possibly leading to the failure of the Keap1-Nrf2 pathway. Until now, several studies have identified changes in Keap1-Nrf2 signaling in models of respiratory diseases, such as acute respiratory distress syndrome (ARDS)/acute lung injury (ALI), chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), and asthma. These studies have confirmed that several Nrf2 activators can alleviate symptoms of respiratory diseases. Thus, this review describes how the expression of Keap1-Nrf2 functions in different respiratory diseases and explains the protective effects of reversing this expression.

Recent Insights Into the Protective Mechanisms of Paeoniflorin in Neurological, Cardiovascular, and Renal Diseases

ABSTRACT

The monoterpene glycoside paeoniflorin (PF) is the principal active constituent of the traditional Chinese herbal medicines, Radix Paeoniae Alba and Radix Paeoniae Rubra, which have been used for millennia to treat cardiovascular diseases (eg, hypertension, bleeding, and atherosclerosis) and neurological ailments (eg, headaches, vertigo, dementia, and pain). Recent evidence has revealed that PF exerts inhibitory effects on inflammation, fibrosis, and apoptosis by targeting several intracellular signaling cascades. In this review, we address the current knowledge about the pharmacokinetic properties of PF and its molecular mechanisms of action. We also present results from recent preclinical studies supporting the utility of PF for the treatment of pain, cerebral ischemic injury, and neurodegenerative diseases, such as Alzheimer's and Parkinson's diseases. Moreover, new evidence suggests a general protective role of PF in heart attack, diabetic kidney, and atherosclerosis. Mechanistically, PF exerts multiple anti-inflammatory actions by targeting toll-like receptor-mediated signaling in both parenchymal and immune cells (in particular, macrophages and dendritic cells). A better understanding of the molecular actions of PF may lead to the expansion of its therapeutic uses.

Classes of drugs that target the cellular components of inflammation under clinical development for COPD

INTRODUCTION

The persistent inflammation that characterizes COPD and affects its natural course also impacting on symptoms has prompted research to find molecules that can regulate the inflammatory process but still available anti-inflammatory therapies provide little or no benefit in COPD patients. Consequently, numerous anti-inflammatory molecules that are effective in animal models of COPD have been or are being evaluated in humans.

AREAS COVERED

In this article we describe several classes of drugs that target the cellular components of inflammation under clinical development for COPD.

EXPERT OPINION

Although the results of many clinical trials with new molecules have often been disappointing, several studies are underway to investigate whether some of these molecules may be effective in treating specific subgroups of COPD patients. Indeed, the current perspective is to apply a more personalized treatment to the patient. This means being able to better define the patient's inflammatory state and treat it in a targeted manner. Unfortunately, the difficulty in translating encouraging experimental data into human clinical trials, the redundancy in the effects induced by signal-transmitting substances and the nonspecific effects of many classes that are undergoing clinical trials, do not yet allow specific inflammatory cell types to be targeted.

Nrf2 modulated the restriction of lung function via impairment of intrinsic autophagy upon real-ambient PM2.5 exposure

Compelling studies approve that fine particle matter (PM_2.5) exposure was associated with high risk of respiratory disorders. However, the available data assessing the detailed influence of PM_2.5 on lung was limited. To overcome the difficulty of inhalational PM_2.5 exposure, the real-ambient PM_2.5 exposure system was constructed. The mice were exposed to filtered air (FA) or real-ambient PM_2.5 (PM_2.5), and the adverse effect on lung was determined. Nuclear factor E2-related factor 2 (Nrf2) as a transcription factor, was reported to affect autophagy. Autophagy was proposed as a two-edge sword in respiratory disorders. Here, our data presented that PM_2.5 exposure dramatically reduced the lung function of WT mice rather than Nrf2^-/- mice. Consistently, thickened alveolar walls was observed in WT mice in PM_2.5 exposure group, whereas the histological phenotype of Nrf2^-/- mice exhibited no obvious alteration. Furthermore, PM_2.5 exposure triggered low-grade production of inflammatory profile in WT and Nrf2^-/- mice. Moreover, the protein levels of p62, Beclin1 and LC3B of WT mice rather than Nrf2^-/- mice were also altered in PM_2.5 exposure group. Taken together, the present study applied the real-ambient exposure system, revealed the adverse effect of air pollution on lung, and proposed the underlying mechanism.

Rhodiola rosea L. Attenuates Cigarette Smoke and Lipopolysaccharide-Induced COPD in Rats via Inflammation Inhibition and Antioxidant and Antifibrosis Pathways

The root cause behind the development of chronic obstructive pulmonary disease (COPD) is cigarette smoke that induces the inflammation of the lung tissue and alveolar destruction. Long-term cigarette smoking can lead to deterioration in lung parenchymal function and cause structural changes in the lung, further resulting in pulmonary fibrosis. Rhodiola rosea L., a traditional medicinal perennial herb, is well known for its numerous pharmacological benefits, including anti-inflammation, antioxidant, antifatigue, antidepressive, and antifibrotic properties. Here, we evaluated the pharmacological effects and mechanisms of the Rhodiola rosea L. (RRL) macroporous resin extract on COPD caused by lipopolysaccharide (LPS) and cigarette smoke (CS) in rats. The RRL significantly improved the pathological structure of the lung tissue. Additionally, RRL decreased the infiltration of inflammatory cells and, subsequently, oxidative stress. Furthermore, the RNAseq assay indicated that RRL attenuated the CS and LPS-induced COPD via anti-inflammatory, antifibrotic, and antiapoptotic activities. Western blot analysis substantiated that the RRL resulted in upregulated levels of Nrf2 and HO-1 as well as downregulated levels of IκBα, NF-κB p65, α-SMA, and TGF-β1. Interestingly, the RRL could protect rats from CS and LPS-induced COPD by inhibiting the ERK1/2 and Smad3 signaling pathways and apoptosis. Thus, the RRL could attenuate CS and LPS-induced COPD through inflammation inhibition and antioxidant and antifibrosis pathways.

Allyl isothiocyanate increases MRP1 expression in cigarette smoke extract-stimulated human bronchial epithelial cells via the JNK/Nrf2 pathway

Multidrug resistance-related protein 1 (MRP1) is involved in the biological transport of several molecules with diverse structural characteristics outside of the cell. In addition to its transport activity, MRP1 exhibits multiple defense mechanisms in vivo. MRP1 is highly expressed in normal lung tissues and plays a protective role in the process of chronic obstructive pulmonary disease. In the present study, human bronchial epithelial cells (16HBE14o-cells) were stimulated by cigarette smoke extract (CSE) in vitro to simulate a smoking environment. On this basis, the mechanism of Allyl isothiocyanate (AITC) administration on the expression of MRP1 in CSE-stimulated 16HBE14o-cells was investigated. The effects of CSE on the viability of 16 HBE14o-cells were investigated by an MTT assay. The changes in the mRNA expression levels of nuclear erythroid factor 2 (Nrf2) and MRP1 were investigated in CSE-stimulated 16HBE14o-cells using western blotting and reverse transcription quantitative PCR (RT-qPCR). Immunofluorescence analysis was used to detect Nrf2 nuclear translocation. Incubation of the cells with 5% CSE for 24 h had minor effects on cell viability and resulted in the activation of the JNK and p38MAPK signaling pathways. AITC activated the JNK pathway, inhibited the activation of the p38MAPK pathway in 16HBE14o-cells stimulated by 5% CSE and upregulated the expression levels of Nrf2 and MRP1 in a time-dependent manner. The upregulation of Nrf2, MRP1 and of Nrf2, and MRP1 mRNA expression levels in CSE-stimulated cells was inhibited by pretreatment with SP600125 (a JNK pathway inhibitor). Furthermore, the fluorescence intensity in the nucleus was significantly enhanced following AITC pretreatment and the analysis indicated nuclear translocation of Nrf2 in the cells. These results indicated that Nrf2 and MRP1 expression levels in CSE-stimulated cells were altered following AITC pretreatment. Thus demonstrating that the primary mechanism may be associated with activation of the JNK pathway, while the p38MAPK pathway may not be involved.

Potential Role of Antioxidant and Anti-Inflammatory Therapies to Prevent Severe SARS-Cov-2 Complications

The coronavirus disease 2019 (COVID-19) pandemic is caused by a novel severe acute respiratory syndrome (SARS)-like coronavirus (SARS-CoV-2). Here, we review the molecular pathogenesis of SARS-CoV-2 and its relationship with oxidative stress (OS) and inflammation. Furthermore, we analyze the potential role of antioxidant and anti-inflammatory therapies to prevent severe complications. OS has a potential key role in the COVID-19 pathogenesis by triggering the NOD-like receptor family pyrin domain containing 3 inflammasome and nuclear factor-kB (NF-kB). While exposure to many pro-oxidants usually induces nuclear factor erythroid 2 p45-related factor2 (NRF2) activation and upregulation of antioxidant related elements expression, respiratory viral infections often inhibit NRF2 and/or activate NF-kB pathways, resulting in inflammation and oxidative injury. Hence, the use of radical scavengers like N-acetylcysteine and vitamin C, as well as of steroids and inflammasome inhibitors, has been proposed. The NRF2 pathway has been shown to be suppressed in severe SARS-CoV-2 patients. Pharmacological NRF2 inducers have been reported to inhibit SARS-CoV-2 replication, the inflammatory response, and transmembrane protease serine 2 activation, which for the entry of SARS-CoV-2 into the host cells through the angiotensin converting enzyme 2 receptor. Thus, NRF2 activation may represent a potential path out of the woods in COVID-19 pandemic.

Antioxidative effect of DJ-1 is enhanced in NG108-15 cells by DPMQ-induced copper influx

Disruption of copper homeostasis is closely involved in neurodegenerative disorders. This study examined whether a hybrid copper-binding compound, (E)-2-(4-(dimethylamino)phenylimino)methyl)quinolin-8-ol (DPMQ), is able to protect NG108-15 cells against oxidative stress. We found that treatment of cells with rotenone or hydrogen peroxide increased cellular oxidative stress and resulted in mitochondrial dysfunction and apoptosis. The cellular levels of Nrf2 and the Cu²⁺ chaperone DJ-1 were also decreased. These oxidative detrimental effects were all inhibited when cells were cotreated with DPMQ. DPMQ increased cellular Cu²⁺ content, DJ-1 protein level, superoxide dismutase (SOD) activity, and Nrf2 nuclear translocation under basal state. The activity of SOD decreased under redox imbalance and this decrease was blocked by DPMQ treatment, while the protein level of SOD1 remained unaltered regardless of the oxidative stress and DPMQ treatment. Using endogenous proteins, coimmunoprecipitation showed that DJ-1 bound with SOD1 and Nrf2 individually. The amount of Nrf2, bound to DJ-1, consistently reflected its cellular level, while the amount of SOD1, bound to DJ-1, was potentiated by DPMQ, being greater in the basal state than under redox imbalance. Simultaneous inclusion of nonpermeable Cu²⁺ chelator tetrathiomolybdate or triethylenetetramine during DPMQ treatment blocked all aforementioned effects of DPMQ, showing that the dependency of the effect of DPMQ on extracellular Cu²⁺. In addition, silencing of DJ-1 blocked the protection of DPMQ against oxidative stress. Taken all together, our results suggest that DPMQ stabilizes DJ-1 in a Cu²⁺-dependent manner, which then brings about SOD1 activation and Nrf2 nuclear translocation; these together alleviate cellular oxidative stress.

AITC induces MRP1 expression by protecting against CS/CSE-mediated DJ-1 protein degradation via activation of the DJ-1/Nrf2 axis

The present study aimed to examine the effect of allyl isothiocyanate (AITC) on chronic obstructive pulmonary disease and to investigate whether upregulation of multidrug resistance-associated protein 1 (MRP1) associated with the activation of the PARK7 (DJ-1)/nuclear factor erythroid 2-related factor 2 (Nrf2) axis. Lung function indexes and histopathological changes in mice were assessed by lung function detection and H&E staining. The expression levels of Nrf2, MRP1, heme oxygenase-1 (HO-1), and DJ-1 were determined by immunohistochemistry, Western blotting and reverse transcription-quantitative polymerase chain reaction. Next, the expression of DJ-1 in human bronchial epithelial (16HBE) cells was silenced by siRNA, and the effect of DJ-1 expression level on cigarette smoke extract (CSE)-stimulated protein degradation and AITC-induced protein expression was examined. The expression of DJ-1, Nrf2, HO-1, and MRP1 was significantly decreased in the wild type model group, while the expression of each protein was significantly increased after administration of AITC. Silencing the expression of DJ-1 in 16HBE cells accelerated CSE-induced protein degradation, and significantly attenuated the AITC-induced mRNA and protein expression of Nrf2 and MRP1. The present study describes a novel mechanism by which AITC induces MRP1 expression by protecting against CS/CSEmediated DJ-1 protein degradation via activation of the DJ-1/Nrf2 axis.