Role of Nrf2 in the pathogenesis of respiratory diseases

Repeated Silica exposures lead to Silicosis severity via PINK1/PARKIN mediated mitochondrial dysfunction in mice model

BACKGROUND AND OBJECTIVES

Silicosis, one of the occupational health illnesses is caused by inhalation of crystalline silica. Deposition of extracellular matrix and fibroblast proliferation in lungs are linked to silicosis development. Mitochondrial dysfunction plays critical role in some diseases, but how these processes progress and regulated in silicosis, remains limited. Detailed study of silica induced pulmonary fibrosis in mouse model, its progression and severity may be helpful in designing future therapeutic strategies.

METHODS

In present study, mice model of silicosis has been developed after repeated silica exposures which may closely resemble clinical symptoms of silicosis in human. In addition to efficiently mimicking the acute/chronic transformation processes of silicosis, this is practical and efficient in terms of time and output, which avoids mechanical injury to the upper respiratory tract due to surgical interventions. Sonicated sterile silica suspension (120 mg/kg) was administered through intranasal route thrice a week at regular intervals (21, 28 and 35 days).

RESULTS

Presence of minute to larger silicotic nodules in H&E-stained lung sections were observed in all silica induced model groups. Enhanced ECM deposition was noted in MT stained lung sections of silica exposure groups as compared to control which were confirmed by significantly higher MMP9 expression levels and hydroxyproline content in silica 35 days group. Increase in Reactive oxygen species (ROS), inflammatory cell recruitment mainly, neutrophils and macrophage were observed in all three silica exposure groups. Transmission electron microscopic analysis has confirmed presence of many aberrant shaped mitochondria (swollen, round shape) in 35 days model where autophagosomes were minimum. Western blot analysis of mitophagy and autophagy markers such as Pink1, Parkin, Cytochrome c, SQSTM1/p62, the ratio of light chain LC3B II/LC3B I was found higher in 21 and 28 days which were significantly reduced in 35 days silica model.

CONCLUSIONS

Higher MMP9 activity and MMP9 /TIMP1 ratio demonstrate excessive extracellular matrix damage and deposition in 35 days model. Significantly reduced expressions of autophagy and mitophagy markers have also confirmed progression in fibrosis severity and its association with repeated silica exposures in 35 days model group.

Pharmacological profile of dicaffeoylquinic acids and their role in the treatment of respiratory diseases

Dicaffeoylquinic acids (DCQAs) are polyphenolic compounds found in various medicinal plants such as Echinacea species and Hedera helix, whose multi-constituent extracts are used worldwide to treat respiratory diseases. Besides triterpenes, saponins, alkamides, and other constituents, DCQAs are an important group of substances for the pharmacological activity of plant-derived extracts. Therefore, the pharmacological properties of DCQAs have been studied over the last decades, suggesting antioxidative, anti-inflammatory, antimicrobial, hypoglycaemic, cardiovascular protective, neuroprotective, and hepatoprotective effects. However, the beneficial pharmacological profile of DCQAs has not yet been linked to their use in treating respiratory diseases such as acute or even chronic bronchitis. The aim of this review was to assess the potential of DCQAs for respiratory indications based on published in vitro and in vivo pharmacological and pre-clinical data, with particular focus on antioxidative, anti-inflammatory, and respiratory-related effects such as antitussive or antispasmodic properties. A respective literature search revealed a large number of publications on the six DCQA isoforms. Based on this search, a focus was placed on 1,3-, 3,4-, 3,5-, and 4,5-DCQA, as the publications focused mainly on these isomers. Based on the available pre-clinical data, DCQAs trigger cellular mechanisms that are important in the treatment of respiratory diseases such as decreasing NF-κB activation, reducing oxidative stress, or activating the Nrf2 pathway. Taken together, these data suggest an essential role for DCQAs within herbal medicines used for the treatment of respiratory diseases and highlights the need for the identifications of DCQAs as lead substances within such extracts.

Benzo[a]pyrene evokes epithelial-mesenchymal transition and pulmonary fibrosis through AhR-mediated Nrf2-p62 signaling

Benzo[a]pyrene (BaP) and its metabolic end product benzo(a)pyren-7,8-dihydrodiol-9,10-epoxide (BPDE), are known toxic environmental pollutants. This study aimed to analyze whether sub-chronic BPDE exposure initiated pulmonary fibrosis and the potential mechanisms. In this work, male C57BL6/J mice were exposed to BPDE by dynamic inhalation exposure for 8 weeks. Our results indicated that sub-chronic BPDE exposure evoked pulmonary fibrosis and epithelial-mesenchymal transition (EMT) in mice. Both in vivo and in vitro, BPDE exposure promoted nuclear translocation of Snail. Further experiments indicated that nuclear factor erythroid 2-related factor 2 (Nrf2) and p62 were upregulated in BPDE-exposed alveolar epithelial cells. Moreover, Nrf2 siRNA transfection evidently attenuated BPDE-induced p62 upregulation. Besides, p62 shRNA inhibited BPDE-incurred Snail nuclear translocation and EMT. Mechanically, BPDE facilitated physical interaction between p62 and Snail in the nucleus, then repressed Snail protein degradation by p62-dependent autophagy-lysosome pathway, and finally upregulated transcriptional activity of Snail. Additionally, aryl hydrocarbon receptor (AhR) was activated in BPDE-treated alveolar epithelial cells. Dual-luciferase assay indicated activating AhR could bind to Nrf2 gene promoter. Moreover, pretreatment with CH223191 or α-naphthoflavone (α-NF), AhR antagonists, inhibited BPDE-activated Nrf2-p62 signaling, and alleviated BPDE-induced EMT and pulmonary fibrosis in mice. Taken together, AhR-mediated Nrf2-p62 signaling contributes to BaP-induced EMT and pulmonary fibrosis.

The Role of Nrf2 in the Regulation of Mitochondrial Function and Ferroptosis in Pancreatic Cancer

The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) represents the master regulator of the cellular antioxidant response and plays a critical role in tumorigenesis. This includes a preventive effect of Nrf2 on cell death through ferroptosis, which represents an essential mechanism of therapy resistance in malignant tumors, such as pancreatic ductal adenocarcinoma (PDAC) as one of the most aggressive and still incurable tumors. Addressing this issue, we provide an overview on Nrf2 mediated antioxidant response with particular emphasis on its effect on mitochondria as the organelle responsible for the execution of ferroptosis. We further outline how deregulated Nrf2 adds to the progression and therapy resistance of PDAC, especially with respect to the role of ferroptosis in anti-cancer drug mediated cell killing and how this is impaired by Nrf2 as an essential mechanism of drug resistance. Our review further discusses recent approaches for Nrf2 inhibition by natural and synthetic compounds to overcome drug resistance based on enhanced ferroptosis. Finally, we provide an outlook on therapeutic strategies based on Nrf2 inhibition combined with ferroptosis inducing drugs.

MAPK15 controls cellular responses to oxidative stress by regulating NRF2 activity and expression of its downstream target genes

Oxidation processes in mitochondria and different environmental insults contribute to unwarranted accumulation of reactive oxygen species (ROS). These, in turn, rapidly damage intracellular lipids, proteins, and DNA, ultimately causing aging and several human diseases. Cells have developed different and very effective systems to control ROS levels. Among these, removal of excessive amounts is guaranteed by upregulated expression of various antioxidant enzymes, through activation of the NF-E2-Related Factor 2 (NRF2) protein. Here, we show that Mitogen Activated Protein Kinase 15 (MAPK15) controls the transactivating potential of NRF2 and, in turn, the expression of its downstream target genes. Specifically, upon oxidative stress, MAPK15 is necessary to increase NRF2 expression and nuclear translocation, by inducing its activating phosphorylation, ultimately supporting transactivation of cytoprotective antioxidant genes. Lungs are continuously exposed to oxidative damages induced by environmental insults such as air pollutants and cigarette smoke. Interestingly, we demonstrate that MAPK15 is very effective in supporting NRF2-dependent antioxidant transcriptional response to cigarette smoke of epithelial lung cells. Oxidative damage induced by cigarette smoke indeed represents a leading cause of disability and death worldwide by contributing to the pathogenesis of different chronic respiratory diseases and lung cancer. Therefore, the development of novel therapeutic strategies able to modulate cellular responses to oxidative stress would be highly beneficial. Our data contribute to the necessary understanding of the molecular mechanisms behind such responses and identify new potentially actionable targets.

Dimethyl fumarate alleviates allergic asthma by strengthening the Nrf2 signaling pathway in regulatory T cells

Allergic asthma is a widely prevalent inflammatory condition affecting people across the globe. T cells and their secretory cytokines are central to the pathogenesis of allergic asthma. Here, we have evaluated the anti-inflammatory impact of dimethyl fumarate (DMF) in allergic asthma with more focus on determining its effect on T cell responses in allergic asthma. By utilizing the ovalbumin (OVA)-induced allergic asthma model, we observed that DMF administration reduced the allergic asthma symptoms and IgE levels in the OVA-induced mice model. Histopathological analysis showed that DMF treatment in an OVA-induced animal model eased the inflammation in the nasal and bronchial tissues, with a particular decrease in the infiltration of immune cells. Additionally, RT-qPCR analysis exhibited that treatment of DMF in an OVA-induced model reduced the expression of inflammatory cytokine (IL4, IL13, and IL17) while augmenting anti-inflammatory IL10 and Foxp3 (forkhead box protein 3). Mechanistically, we found that DMF increased the expression of Foxp3 by exacerbating the expression of nuclear factor E2-related factor 2 (Nrf2), and the in-vitro activation of Foxp3+ Tregs leads to an escalated expression of Nrf2. Notably, CD4-specific Nrf2 deletion intensified the allergic asthma symptoms and reduced the in-vitro iTreg differentiation. Meanwhile, DMF failed to exert protective effects on OVA-induced allergic asthma in CD4-specific Nrf2 knock-out mice. Overall, our study illustrates that DMF enhances Nrf2 signaling in T cells to assist the differentiation of Tregs, which could improve the anti-inflammatory immune response in allergic asthma.

Salecan ameliorates LPS-induced acute lung injury through regulating Keap1-Nrf2/HO-1 pathway in mice

Acute lung injury (ALI) is a severe clinical condition with high mortality, characterized by rapid onset and limited treatment options. The pathogenesis of ALI involves inflammation and oxidative stress. The polysaccharide salecan, a water-soluble β-(1,3)-D-glucan, has been found to possess numerous pharmaceutical effects, including anti-inflammatory properties, inhibition of oxidative stress, and anti-fatigue effects. This study aims to investigate the protective effect and underlying mechanism of salecan against LPS-induced ALI in mice. Using an in vivo LPS-induced ALI mouse model and an in vitro RAW264.7 cell system, we investigated the role of salecan in ALI with various experimental approaches, including histological staining, quantitative real-time PCR, flow cytometry, western blot analysis, and other relevant assays. Pre-treatment with salecan effectively attenuated LPS-induced ALI in vivo, reducing the severity of pulmonary edema, inflammation, and oxidative stress. NMR-based metabolomic profiling analysis revealed that salecan attenuated LPS-induced metabolic imbalances associated with ALI. Furthermore, salecan downregulated Keap1 and upregulated Nrf2 and HO-1 protein levels, indicating its modulation of the Keap1-Nrf2/HO-1 signaling pathway as a potential mechanism underlying its protective effects against ALI. In vitro studies on RAW264.7 cells revealed that salecan exhibited binding affinity towards macrophages, thereby alleviating LPS-induced apoptosis and inflammation, which underpin its therapeutic potential against ALI. Our study suggests that salecan can alleviate LPS-induced ALI by modulating oxidative stress, inflammatory response, and apoptosis through the activation of the Keap1-Nrf2/HO-1 pathway. These findings provide novel insights into the potential therapeutic use of salecan for the treatment of ALI.

Transcription Factor NRF2 in Shaping Myeloid Cell Differentiation and Function

NFE2-related factor 2 (NRF2) is a master transcription factor (TF) that coordinates key cellular homeostatic processes including antioxidative responses, autophagy, proteostasis, and metabolism. The emerging evidence underscores its significant role in modulating inflammatory and immune processes. This chapter delves into the role of NRF2 in myeloid cell differentiation and function and its implication in myeloid cell-driven diseases. In macrophages, NRF2 modulates cytokine production, phagocytosis, pathogen clearance, and metabolic adaptations. In dendritic cells (DCs), it affects maturation, cytokine production, and antigen presentation capabilities, while in neutrophils, NRF2 is involved in activation, migration, cytokine production, and NETosis. The discussion extends to how NRF2's regulatory actions pertain to a wide array of diseases, such as sepsis, various infectious diseases, cancer, wound healing, atherosclerosis, hemolytic conditions, pulmonary disorders, hemorrhagic events, and autoimmune diseases. The activation of NRF2 typically reduces inflammation, thereby modifying disease outcomes. This highlights the therapeutic potential of NRF2 modulation in treating myeloid cell-driven pathologies.

Impact of GSM-EMW exposure on the markers of oxidative stress in fetal rat liver

The current study investigated the effects of 24 h/day prenatal exposure to global system for mobile communication electromagnetic fields (GSM-EMFs), 900 MHZ-induced electromagnetic radiation (EMR), on oxidative stress (OS) status, apoptotic, and inflammatory changes in liver of rats during their fetal development period. Fifty-two Sprague-Dawley pregnant rats were equally divided into control and exposed groups. Whole embryos were removed at 7.5 dpc (days post coitus), while liver tissues were extracted from embryos at 11.5, 15.5, and 19.5 dpc. For exposed animals, results showed an increased OS reflected by high levels of malondialdehyde (MDA), a decrease in cytosolic superoxide dismutase (cytoSOD) activity, in mitochondrial superoxide dismutase (mitoSOD) levels and catalase (CAT) mRNA expression but also in hepatic nuclear factor erythroïd 2-related Factor 2 (Nrf-2), protein kinase B (Akt1), and intercellular adhesion molecule-1 (ICAM-1) mRNA expression at 15.5 dpc. Moreover, GSM-EMR exposure was shown to significantly decrease mitoSOD and CAT activities at almost all studied ages. Thus, rat embryos may be protected by their mothers from OS, apoptotic, and pro-inflammatory responses till a sensitive developmental stage, during a continuous prenatal EMR exposure. This protection could be then created from the embryos themselves.

Sestrin2/Keap1/Nrf2 pathway regulates mucus hypersecretion in pulmonary epithelium induced by traffic-related PM2.5 and water-soluble extracts

The involvement of fine particulate matter (PM2.5) exposure in the progression of asthma has been extensively discussed in epidemiological and experimental evidence, which aroused widespread attention. Asthma is characterized by mucus hypersecretion. This study investigates the underlying toxic mechanism of traffic-related PM2.5 (TRPM2.5) and water-soluble extracts (WSE) on mucus hypersecretion in the lungs of rats with asthma and 16HBE cells. The ovalbumin-induced rats were administrated by instillation of TRPM2.5 and WSE in the trachea once three days for eight times. The results showed that TRPM2.5 and WSE had an adverse impact on mucus secretion. Specifically, conspicuous mucus stains and increased goblet cells in the bronchial epithelium by PAS staining were found in lung tissues of rats with asthma; MUC5AC gene and protein expression levels in lung tissues of rats with asthma and 16HBE cells were elevated. In addition, TRPM2.5 and WSE triggered oxidative damage via upregulation of malondialdehyde and myeloperoxidase as well as activation of the Sestrin2/Keap1/Nrf2 signaling pathway. Conversely, the knockdown of Sestrin2 effectively inhibited TRPM2.5 and WSE-induced mucus hypersecretion, oxidative stress, and Keap1/Nrf2 signaling pathway and its downstream target gene NQO1. Collectively, it was demonstrated that TRPM2.5 and WSE induced mucus hypersecretion mediated by the Sestrin2/Keap1/Nrf2 pathway.

Lansoprazole attenuates cyclophosphamide-induced cardiopulmonary injury by modulating redox-sensitive pathways and inflammation

Cyclophosphamide (CPA) is a classical chemotherapeutic drug widely used as an anticancer and immunosuppressive agent. However, it is frequently associated with significant toxicities to the normal cells of different organs, including the lung and heart. Lansoprazole (LPZ), a proton pump inhibitor (PPI), possesses antioxidant and anti-inflammatory properties. The current study investigated how LPZ protects against CPA-induced cardiac and pulmonary damage, focusing on PPARγ, Nrf2, HO-1, cytoglobin, PI3K/AKT, and NF-κB signaling. Animals were randomly assigned into four groups: normal control group (received vehicle), LPZ only group (Rats received LPZ at a dose of 50 mg/kg/day P.O. for 10 days), CPA group (CPA was administered (200 mg/kg) as a single i.p. injection on the 7th day), and cotreatment group (LPZ plus CPA). Histopathological and biochemical analyses were conducted. Our results revealed that LPZ treatment revoked CPA-induced heart and lung histopathological alterations. Also, LPZ potently mitigated CPA-induced cardiac and pulmonary oxidative stress through the activation of PPARγ, Nrf2/HO-1, cytoglobin, and PI3K/AKT signaling pathways. Also, LPZ effectively suppressed inflammatory response as evidenced by down-regulating the inflammatory strategic controller NF-κB, MPO, and pro-inflammatory cytokines. The present findings could provide a mechanistic basis for understanding LPZ's role in CPA-induced cardiopulmonary injury through the alleviation of oxidative stress and inflammatory burden.

Alkaloids as Natural NRF2 Inhibitors: Chemoprevention and Cytotoxic Action in Cancer

Being a controller of cytoprotective actions, inflammation, and mitochondrial function through participating in the regulation of multiple genes in response to stress-inducing endogenous or exogenous stressors, the transcription factor Nuclear Factor Erythroid 2-Related Factor 2 (NRF2) is considered the main cellular defense mechanism to maintain redox balance at cellular and tissue level. While a transient activation of NRF2 protects normal cells under oxidative stress, the hyperactivation of NRF2 in cancer cells may help them to survive and to adapt under oxidative stress. This can be detrimental and related to cancer progression and chemotherapy resistance. Therefore, inhibition of NRF2 activity may be an effective approach for sensitizing cancer cells to anticancer therapy. In this review, we examine alkaloids as NRF2 inhibitors from natural origin, their effects on cancer therapy, and/or as sensitizers of cancer cells to anticancer chemotherapeutics, and their potential clinical applications. Alkaloids, as inhibitor of the NRF2/KEAP1 signaling pathway, can have direct (berberine, evodiamine, and diterpenic aconitine types of alkaloids) or indirect (trigonelline) therapeutic/preventive effects. The network linking alkaloid action with oxidative stress and NRF2 modulation may result in an increased NRF2 synthesis, nuclear translocation, as well in a downstream impact on the synthesis of endogenous antioxidants, effects strongly presumed to be the mechanism of action of alkaloids in inducing cancer cell death or promoting sensitivity of cancer cells to chemotherapeutic agents. In this regard, the identification of additional alkaloids targeting the NRF2 pathway is desirable and the information arising from clinical trials will reveal the potential of these compounds as a promising target for anticancer therapy.

The thioredoxin expression of Cristaria plicata is regulated by Nrf2/ARE pathway under microcystin stimulation

Thioredoxin plays an important role in inhibiting apoptosis and protecting cells from oxidative stress. This study was aimed to clarify how the expression of Trx from Cristaria plicata is regulated by Nrf2/ARE pathway. The expression of CpTrx mRNA was significantly up-regulated in gill and kidney tissues under microcystin stress. The Nrf2 gene of Cristaria plicata was identified to possess an auto active domain bit. While CpNrf2 was knocked down by specific small RNA, CpTrx mRNA expression was significantly down-regulated. The promoter of CpTrx gene had high transcriptional activity, and this basic transcriptional activity persisted after ARE element mutation. The region of promoter -206 to +217 bp was a core promoter region and had forward regulatory elements. Gel shift Assay exhibited that the CpTrx promoter could bind to the purified proteins CpNrf2 and CpMafK in vitro. The binding phenomenon disappeared after the ARE element mutation in promoter region. Subcellular localization experiments displayed that fluorescence overlap between CpNrf2 and Trx promoter increased under microcystin toxin stress. These results suggested that Trx expression was regulated by Nrf2/ARE pathway under oxidative stress.

Azithromycin ameliorated cigarette smoke-induced airway epithelial barrier dysfunction by activating Nrf2/GCL/GSH signaling pathway

BACKGROUND

Airway epithelium is the first barrier against environmental insults, and epithelial barrier dysfunction caused by cigarette smoke (CS) is particularly relevant to chronic obstructive pulmonary disease (COPD) progression. Our study was to determine whether Azithromycin (AZI) ameliorates CS-induced airway epithelial barrier dysfunction and the underlying mechanisms.

METHODS

Primary bronchial epithelial cells (PBECs), human bronchial epithelial cells (HBECs), Sprague Dawley rats and nuclear factor erythroid 2-related factor 2 (Nrf2)-/- mice were pretreated with AZI and subsequently exposed to CS. Transepithelial electronic resistance (TEER), junction proteins as well as pro-inflammatory cytokines and apoptosis markers were examined to assess epithelial barrier dysfunction. Metabolomics study was applied to explore the underlying mechanism of AZI.

RESULTS

CS-induced TEER decline and intercellular junction destruction, accompanied with inflammatory response and cell apoptosis in PBECs were restored by AZI dose-dependently, which were also observed in CS-exposed rats. Mechanistically, GSH metabolism pathway was identified as the top differentially impacted pathway and AZI treatment upregulated the activities of glutamate cysteine ligase (GCL) and the contents of metabolites in GSH metabolic pathway. Furthermore, AZI apparently reversed CS-induced Nrf2 suppression, and similar effects on airway epithelial barrier dysfunction were also found for Nrf2 agonist tert-butylhydroquinone and vitamin C. Finally, deletion of Nrf2 in both HBECs and C57BL/6N mice aggravated CS-induced GSH metabolism imbalance to disrupt airway epithelial barrier and partially deprived the effects of AZI.

CONCLUSION

These findings suggest that the clinical benefits of AZI for COPD management are related with the protection of CS-induced airway epithelial barrier dysfunction via activating Nrf2/GCL/GSH pathway, providing potential therapeutic strategies for COPD.

Expression of Nrf2 protein in serum of patients with rheumatoid arthritis: A novel indicator for disease activity and disease prognosis

OBJECTIVE

This study aimed to detect the expression level of nuclear factor erythroid 2-related factor 2 (Nrf2) in the serum of patients with rheumatoid arthritis (RA) to clarify the correlation between Nrf2 levels and medical parameters, such as disease activity, pro-inflammatory factor, clinical characteristics, as well as changes after treatment.

METHODS

Serum samples were collected from 100 patients with RA and 42 normal controls (NCs). Serum levels of Nrf2 protein, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), interleukin-17A, and malondialdehyde (MDA) were analyzed. The receiver operating characteristic (ROC) curve was adopted to assess the potential of Nrf2 to predict different levels of disease activity in patients with RA. The relationship between clinical variables and parameters were evaluated.

RESULTS

For the first time, it was reported that Nrf2 levels were significantly elevated in the serum of patients with RA compared to those of NCs, as were the MDA levels. The levels of Nrf2 were positively correlated with the disease activity and pro-inflammatory factor levels. The significant cut-off points for Nrf2 to determine RA disease activity were 0.69 ng/mL, 0.69 ng/mL and 1.18 ng/mL. Levels of Nrf2 were higher in RA patients with wrist joint involvement and interstitial lung disease. Moreover, Nrf2 levels decreased after treatment.

CONCLUSIONS

Serum Nrf2 protein level is potentially a novel indicator to monitor disease activity and prognosis in patients with RA.

The effects of lipoic acid on respiratory diseases

Respiratory diseases, including lung cancer, pulmonary fibrosis, asthma, and the recently emerging fatal coronavirus disease-19 (COVID-19), are the leading causes of illness and death worldwide. The increasing incidence and mortality rates have attracted much attention to the prevention and treatment of these conditions. Lipoic acid (LA), a naturally occurring organosulfur compound, is not only essential for mitochondrial aerobic metabolism but also shows therapeutic potential via certain pharmacological effects (e.g., antioxidative and anti-inflammatory effects). In recent years, accumulating evidence (animal experiments and in vitro studies) has suggested a role of LA in ameliorating many respiratory diseases (e.g., lung cancer, fibrosis, asthma, acute lung injury and smoking-induced lung injury). Therefore, this review will provide an overview of the present investigational evidence on the therapeutic effect of LA against respiratory diseases in vitro and in vivo. We also summarize the corresponding mechanisms of action to inspire further basic studies and clinical trials to confirm the health benefits of LA in the context of respiratory diseases.

Biological and Genetic Mechanisms of COPD, Its Diagnosis, Treatment, and Relationship with Lung Cancer

Chronic obstructive pulmonary disease (COPD) is one of the most prevalent chronic adult diseases, with significant worldwide morbidity and mortality. Although long-term tobacco smoking is a critical risk factor for this global health problem, its molecular mechanisms remain unclear. Several phenomena are thought to be involved in the evolution of emphysema, including airway inflammation, proteinase/anti-proteinase imbalance, oxidative stress, and genetic/epigenetic modifications. Furthermore, COPD is one main risk for lung cancer (LC), the deadliest form of human tumor; formation and chronic inflammation accompanying COPD can be a potential driver of malignancy maturation (0.8-1.7% of COPD cases develop cancer/per year). Recently, the development of more research based on COPD and lung cancer molecular analysis has provided new light for understanding their pathogenesis, improving the diagnosis and treatments, and elucidating many connections between these diseases. Our review emphasizes the biological factors involved in COPD and lung cancer, the advances in their molecular mechanisms' research, and the state of the art of diagnosis and treatments. This work combines many biological and genetic elements into a single whole and strongly links COPD with lung tumor features.

An updated patent review of Nrf2 activators (2020-present)

INTRODUCTION

The nuclear factor erythroid 2-related factor 2 (Nrf2) is a pivotal transcription factor that controls the expression of numerous cytoprotective genes and regulates cellular defense system against oxidative insults. Thus, activating the Nrf2 pathway is a promising strategy for the treatment of various chronic diseases characterized by oxidative stress.

AREAS COVERED

This review first discusses the biological effects of Nrf2 and the regulatory mechanism of Kelch-like ECH-associated protein 1-Nrf2-antioxidant response element (Keap1-Nrf2-ARE) pathway. Then, Nrf2 activators (2020-present) are summarized based on the mechanism of action. The case studies consist of chemical structures, biological activities, structural optimization, and clinical development.

EXPERT OPINION

Extensive efforts have been devoted to developing novel Nrf2 activators with improved potency and drug-like properties. These Nrf2 activators have exhibited beneficial effects in in vitro and in vivo models of oxidative stress-related chronic diseases. However, some specific problems, such as target selectivity and brain blood barrier (BBB) permeability, still need to be addressed in the future.

Ellagic acid activates the Keap1-Nrf2-ARE signaling pathway in improving Parkinson's disease: A review

Parkinson's disease (PD) is a familiar neurodegenerative disease, accompanied by motor retardation, static tremor, memory decline and dementia. Heredity, environment, age and oxidative stress have been suggested as key factors in the instigation of PD. The Keap1-Nrf2-ARE signaling is one of the most significant anti- oxidative stress (OS) pathways. The Keap1 is a negative regulator of the Nrf2. The Keap1-Nrf2-ARE pathway can induce cell oxidation resistance and reduce nerve injury to treat neurodegenerative diseases. Ellagic acid (EA) can inhibit the Keap1 to accumulate the Nrf2 in the nucleus, and act on the ARE to produce target proteins, which in turn may alleviate the impact of OS on neuronal cells of PD. This review analyzes the structure and physiological role of EA, along with the structure, composition and functions of the Keap1-Nrf2-ARE signaling pathway. We further expound on the mechanism of ellagic acid in its activation of the Keap1-Nrf2-ARE signaling pathway, as well as the relationship between EA in impairing the TLR4/Myd88/NF-κB and Nrf2 pathways. Ellagic acid has the potentiality of improving PD by activating the Keap1-Nrf2-ARE signaling pathway and scavenging free radicals.

Cigarette smoke induces pulmonary arterial dysfunction through an imbalance in the redox status of the soluble guanylyl cyclase

Chronic obstructive pulmonary disease (COPD), whose main risk factor is cigarette smoking (CS), is one of the most common diseases globally. Some COPD patients also develop pulmonary hypertension (PH), a severe complication that leads to premature death. Evidence suggests reactive oxygen species (ROS) involvement in COPD and PH, especially regarding pulmonary artery smooth muscle cells (PASMC) dysfunction. However, the effects of CS-driven oxidative stress on the pulmonary vasculature are not completely understood. Herein we provide evidence on the effects of CS extract (CSE) exposure on PASMC regarding ROS production, antioxidant response and its consequences on vascular tone dysregulation. Our results indicate that CSE exposure promotes mitochondrial fission, mitochondrial membrane depolarization and increased mitochondrial superoxide levels. However, this superoxide increase did not parallel a counterbalancing antioxidant response in human pulmonary artery (PA) cells. Interestingly, the mitochondrial superoxide scavenger mitoTEMPO reduced mitochondrial fission and membrane potential depolarization caused by CSE. As we have previously shown, CSE reduces PA vasoconstriction and vasodilation. In this respect, mitoTEMPO prevented the impaired nitric oxide-mediated vasodilation, while vasoconstriction remained reduced. Finally, we observed a CSE-driven downregulation of the Cyb5R3 enzyme, which prevents soluble guanylyl cyclase oxidation in PASMC. This might explain the CSE-mediated decrease in PA vasodilation. These results provide evidence that there might be a connection between mitochondrial ROS and altered vasodilation responses in PH secondary to COPD, and strongly support the potential of antioxidant strategies specifically targeting mitochondria as a new therapy for these diseases.

The Relationship between Nrf2 and HO-1 with the Severity of COVID-19 Disease

Nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) have significant roles in the development of a hyperinflammatory state in infectious diseases. We aimed to investigate the association of the serum concentrations of Nrf2 and HO-1 with the severity of COVID-19 disease. The study included 40 subjects with mild and moderately severe forms of the disease (MEWS scoring system ≤2). Twenty of the subjects had MEWS scores of 3 or 4, which indicate a severe form of the disease, and twenty subjects had a MEWS score of ≥5, which indicates a critical form of the disease. HO-1 and Nrf2 were measured using the commercially available Enzyme-Linked Immunosorbent Assay (ELISA). Subjects with the most severe form of COVID-19 (critically ill) had a lower concentration of Nrf2 that negatively correlated with the markers of hyperinflammatory response (CRP, IL-6, ferritin). This observation was not made for HO-1, and the correlation between Nrf2 and HO-1 values was not established. In the mild/moderate form of COVID-19 disease, Nrf2 was associated with an increased 1,25 dihydroxy vitamin D concentration. The results of this study show that Nrf2 has a role in the body's anti-inflammatory response to COVID-19 disease, which makes it a potential therapeutic target.

Pathological Mechanism and Targeted Drugs of COPD

Chronic obstructive pulmonary disease (COPD) includes chronic bronchitis, emphysema, and small airway obstruction. Incompletely reversible airflow limitation, inflammation, excessive mucus secretion and bronchial mucosal epithelial lesions are the main pathological basis of the disease. The prevalence of COPD is increasingly worldwide, which has caused the burden on individuals and society. This paper summarizes the pathogenesis of COPD and clarifies the effect and mechanism of the latest targeted drugs for COPD. Besides, we focus on NOD-like receptor thermal protein domain associated protein 3 inflammasome (NLRP3 inflammasome). NLRP3 can promote production of interleukin-1β (IL-1β) and interleukin-18 (IL-18). NLRP3 is an important factor in the migratory aggregation of macrophages and neutrophils and the generation of oxidative stress. Inhibition of NLRP3 inflammasome indirectly blocks the inflammatory effects of IL-1β and IL-18, which may be regarded as an ideal target for COPD treatment.

Effects of Antioxidants in Human Milk on Bronchopulmonary Dysplasia Prevention and Treatment: A Review

Bronchopulmonary dysplasia (BPD) is a severe chronic lung illness that affects neonates, particularly premature infants. It has far-reaching consequences for infant health and their families due to intractable short- and long-term repercussions. Premature infant survival and long-term quality of life are severely harmed by BPD, which is characterized by alveolarization arrest and hypoplasia of pulmonary microvascular cells. BPD can be caused by various factors, with oxidative stress (OS) being the most common. Premature infants frequently require breathing support, which results in a hyperoxic environment in the developing lung and obstructs lung growth. OS can damage the lungs of infants by inducing cell death, inhibiting alveolarization, inducing inflammation, and impairing pulmonary angiogenesis. Therefore, antioxidant therapy for BPD relieves OS and lung injury in preterm newborns. Many antioxidants have been found in human milk, including superoxide dismutase, glutathione peroxidase, glutathione, vitamins, melatonin, short-chain fatty acids, and phytochemicals. Human milk oligosaccharides, milk fat globule membrane, and lactoferrin, all unique to human milk, also have antioxidant properties. Hence, human milk may help prevent OS injury and improve BPD prognosis in premature infants. In this review, we explored the role of OS in the pathophysiology of BPD and related signaling pathways. Furthermore, we examined antioxidants in human milk and how they could play a role in BPD to understand whether human milk could prevent and treat BPD.

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.

Melatonin attenuates LPS-induced pyroptosis in acute lung injury by inhibiting NLRP3-GSDMD pathway via activating Nrf2/HO-1 signaling axis

Acute lung injury (ALI)/ acute respiratory distress syndrome (ARDS) is featured by intensive inflammatory responses and oxidative stress, which lead to cytokine storms and pyroptosis. Here, we aimed to investigate whether melatonin was capable of alleviating LPS-induced ALI via activating the nuclear factor erythroid 2-related factor 2/heme oxygenase 1 (Nrf2/HO-1) signaling axis and inhibiting pyroptosis. Mice were injected with melatonin (30 mg/kg) intraperitoneally for consecutive five days before LPS instillation intratracheally, and human alveolar epithelial cell (AECⅡ) A549 cell lines and murine macrophages Raw264.7 cell lines were pretreated with melatonin (400 μM) before LPS (10 μg/ml) stimulation. The result demonstrated that LPS induced obvious lung injury characterized by alveolar damage, neutrophil infiltration and lung edema as well as the reduction of the survival rate of mice, which were totally reversed by melatonin pretreatment. Mechanistically, melatonin pretreatment activated nuclear factor erythroid2-related factor (Nrf) 2 signaling, subsequently, drove antioxidant pathways including significant increases in the expression of Nrf2, HO-1, NQO1, Mn-SOD and Catalase in vivo and in vitro. Simultaneously, melatonin inhibited ROS and MDA overproduction, iNOS expression as well as TNF-α and IL-1β expression and release. Furthermore, melatonin inhibited LPS-induced pyroptosis by reversing the overexpression of NLRP3, Caspase-1, IL-1β, IL-18 and GSDMD-N, as well as LDH release and TUNEL-positive cells in A549 cells and Raw264.7 cells. Overall, the current study suggests that melatonin exerts protective roles on LPS-induced ALI and pyroptosis by inhibiting NLRP3-GSDMD pathway via activating Nrf2/HO-1 signaling axis.

Isopanepoxydone inhibits oxidative damage in murine alveolar macrophages via NRF2 and NLRP3 inflammasome

BACKGROUND

Respiratory diseases due to particulate matter are a serious health issue. We sought to investigate the efficacy of isopanepoxydone (ISO) isolated from the Panus rudis as a therapeutic against particulate matter-induced respiratory complications.

MATERIALS AND METHODS

ISO was isolated from a culture broth of Panus rudis using solvent partition, silica gel, and column chromatography, and high-performance liquid chromatography. Its chemical structure was determined spectroscopically. Murine alveolar macrophages (MH-S) were treated with ISO to investigate the inhibition of nitric oxide (NO) while cytotoxicity was investigated via a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. The expression of pro-inflammatory mediators, cytokines, and protein expression levels in the oxidative protective and inflammasome pathway were also investigated. Reactive oxygen species in MH-S cells were investigated using 2',7'-dichlorofluorescein diacetate while immunofluorescence was performed to investigate the expression of activated apoptosis-associated speck-like proteins (ASC) containing a caspase recruitment domain in MH-S cells.

RESULTS

ISO effectively inhibited CFA-induced NO production with no cytotoxicity on MH-S cells and pro-inflammatory mediators and cytokines were also inhibited (except tumor necrosis factor α and interleukin-6). ISO enhanced the protein expression of nuclear factor erythroid 2-related factor 2, while suppressing proteins in the inflammasome pathway, but did not suppress the expression of nuclear factor-kappa B. ISO also reduced detectable ROS other than preventing the activation of ASC.

CONCLUSION

Pathways of action of ISO in MH-S cells that prevent oxidative damage and suppress the expression of proteins in the inflammasome pathway were investigated. ISO may be developed as a treatment for respiratory inflammation.

Common genetic aspects between COVID-19 and sarcoidosis: A network-based approach using gene expression data

The pandemic situation of novel coronavirus disease 2019 (COVID-19) is a global threat on our current planet, with its rapid spread and high mortality rate. Sarcoidosis patients are at high risk to COVID-19 severity for having lung injuries as well as treating with immunosuppressive agents. So, physicians are in dilemma whether they should use immunosuppressive agents or not for the patients with sarcoidosis history and COVID-19 infection. Therefore, common factors should be identified to provide effective treatment. For determining the common genes between COVID-19 and sarcoidosis, GSE164805 and GSE18781 were retrieved from the Gene Expression Omnibus (GEO) database. Common upregulated genes were identified by using R language to investigate their involved pathways and gene ontologies (GO). With the aid of the STRING Cytoscape plugin tool, protein-protein interactions (PPIs) network was constructed. From the PPIs network, Hub genes and essential modules were detected by using Cytohubba, and MCODE respectively. For hub genes, TFs, TFs-miRNA, and drug, interaction networks were built through the NetworkAnalyst web platform. A total of 34 common upregulated genes were identified and among them, five hub genes, including TET2, MUC5AC, VDR, NFE2L2, and BCL6 were determined. In addition, a cluster having VDR and NFE2L2 was detected from the PPIs network. Moreover, 32 transcription factors and 9 miRNA were recognized for hub genes. Furthermore, vitamin D and some of its analogous compounds were obtained from the drug interaction network. In conclusion, hub genes identified in this study might have potential roles in modulating COVID-19 infection and sarcoidosis. However, further studies are required to corroborate this study.

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Sarcoidosis patients are at high risk to COVID-19 severity.

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This study aimed to find out common genetic factors for COVID-19 and Sarcoidosis.

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34 common upregulated genes were identified from GSE164805 and GSE18781 datasets.

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From common upregulated genes, five hub genes, VDR, NFE2L2, BCL6, TET2, and MUC5AC, were recognized.

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Hub genes associated with miRNA, TFs, and drug molecules were also identified.

Cold Plasma Irradiation Regulates Inflammation and Oxidative Stress in Human Bronchial Epithelial Cells and Human Non-Small Cell Lung Carcinoma

Atmospheric pressure cold plasma has shown multiple biological effects of anti-bacteria and anti-cancer. In this study, the effect of atmospheric pressure cold plasma on respiratory inflammation and oxidant stress is explored. Tunicamycin was used to stimulate human bronchial epithelial cells (HBECs) and A549 cells for inflammatory response and oxidative stress, followed by atmospheric pressure cold plasma treatment. For HBECs and A549 cells, atmospheric pressure cold plasma was able to alleviate tunicamycin-induced cell proliferation inhibition, inflammation and oxidant stress, and enhance nuclear factor-erythroid-2-related factor 2 (NRF2) pathway activation. Moreover, NRF2/ARE (anti-oxidant response elements) pathway was involved in the regulation of atmospheric pressure cold plasma on tunicamycin-induced oxidative stress. These results suggest the positive effect of atmospheric pressure cold plasma on inflammation and oxidant stress of respiratory system, indicating the therapeutic potential of atmospheric pressure cold plasma for respiratory diseases.

Suhuang antitussive capsule ameliorates post-infectious cough in mice through AhR-Nrf2 pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Suhuang antitussive capsule (SH capsule), a typical traditional Chinese medicines (TCMs) compound, is widely used for the treatment of post-infectious cough (PIC) in the clinic. Our previous studies have demonstrated that SH capsule possesses significant ameliorative effects on cough variant asthma (CVA), sputum obstruction and airway remodeling.

AIM OF THE STUDY

This study is designed to investigate the ameliorative effects and potential mechanisms of SH capsule on PIC in mice.

MATERIALS AND METHODS

To establish the PIC model, ICR mice were induced by lipopolysaccharide (LPS) (3 mg/kg) once, followed by cigarettes smoke (CS) exposure for 30 min per day for 30 days. Mice were intragastrically (i.g.) administrated with SH capsule at the doses of 3.5, 7, 14 g/kg each day for 2 weeks since the 24th day. The number of coughs, coughs latencies, enzyme-linked immunosorbent assay (ELISA) and histological analysis were used to investigate the effects of SH capsule on PIC mice. Quantitative-polymerase chain reaction (Q-PCR) and western blotting were conducted to evaluate the levels of mRNA and proteins associated with Aryl hydrocarbon receptor (AhR)-NF-E2-related factor 2 (Nrf2) pathway. Superoxide dismutase (SOD), glutathione (GSH) and total antioxidant capacity (T-AOC) assays were performed to evaluate the oxidative stress. A549 cells were used to investigate the ameliorative effects of SH capsule in vitro.

RESULTS

SH capsule effectively diminished the number of coughs and extended coughs latencies in PIC mice. The airway inflammation was alleviated by decreasing the expression levels of inflammatory mediators including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). Moreover, SH capsule dose-dependently activated AhR-Nrf2 pathway and induced the nuclear translocation in vitro and in vivo. Besides, SH capsule significantly increased the levels of SOD, GSH and T-AOC in mice.

CONCLUSION

Our study demonstrates that SH capsule ameliorates airway inflammation-associated PIC in mice through activating AhR-Nrf2 pathway and consequently alleviating inflammatory responses and oxidative stress.

Nutraceuticals and mitochondrial oxidative stress: bridging the gap in the management of bronchial asthma

Asthma is a chronic inflammatory disease primarily characterized by inflammation and reversible bronchoconstriction. It is currently one of the leading causes of morbidity and mortality in the world. Oxidative stress further complicates the pathology of the disease. The current treatment strategies for asthma mainly involve the use of anti-inflammatory agents and bronchodilators. However, long-term usage of such medications is associated with severe adverse effects and complications. Hence, there is an urgent need to develop newer, novel, and safe treatment modalities for the management of asthma. This has therefore prompted further investigations and detailed research to identify and develop novel therapeutic interventions from potent untapped resources. This review focuses on the significance of oxidative stressors that are primarily derived from both mitochondrial and non-mitochondrial sources in initiating the clinical features of asthma. The review also discusses the biological scavenging system of the body and factors that may lead to its malfunction which could result in altered states. Furthermore, the review provides a detailed insight into the therapeutic role of nutraceuticals as an effective strategy to attenuate the deleterious effects of oxidative stress and may be used in the mitigation of the cardinal features of bronchial asthma.

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.

Cimicifugae Rhizoma Extract Attenuates Oxidative Stress and Airway Inflammation via the Upregulation of Nrf2/HO-1/NQO1 and Downregulation of NF-κB Phosphorylation in Ovalbumin-Induced Asthma

Cimicifugae Rhizoma has been used as a medicinal herb for fever, pain, and inflammation in East Asia. We conducted this study because the effect of Cimicifugae Rhizoma extract (CRE) on allergic asthma has not yet been evaluated. To induce allergic airway inflammation, we intraperitoneally injected ovalbumin (OVA) mixed with aluminum hydroxide into mice twice at intervals of 2 weeks (Days 0 and 14) and then inhaled them thrice with 1% OVA solution using a nebulizer (Days 21 to 23). CRE (30 and 100 mg/kg) was administered orally daily for 6 days (Days 18 to 23). The mice showed remarkable reduction in allergic inflammation at 100 mg/kg of CRE, as evidenced by decreased inflammatory cell counts, pro-inflammatory cytokine levels, OVA-specific immunoglobulin E level, airway hyperresponsiveness, and production of mucus. Additionally, these effects were involved with the enhancement of heme oxygenase-1 (HO-1), NAD(P)H: quinone oxidoreductase (NQO1), and nuclear factor erythroid 2-related factor 2 (Nrf2) expression and reduction of nuclear factor-κB (NF-κB) phosphorylation and matrix metalloproteinase-9 expression. Our findings indicated that CRE effectively protected against OVA-induced inflammation and oxidative stress via upregulation of the Nrf2/HO-1/NQO1 signaling and downregulation of NF-κB phosphorylation in asthma caused by OVA.

Iron-Regulated Reactive Oxygen Species Production and Programmed Cell Death in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is characterized by persistent respiratory symptoms and airflow limitation. However, the pathogenesis of COPD remains unclear. Currently, it is known to involve the loss of alveolar surface area (emphysema) and airway inflammation (bronchitis), primarily due to exposure to cigarette smoke (CS). CS causes epithelial cell death, resulting in pulmonary emphysema. Moreover, CS induces iron accumulation in the mitochondria and cytosol, resulting in programmed cell death. Although apoptosis has long been investigated as the sole form of programmed cell death in COPD, accumulating evidence indicates that a regulated form of necrosis, called necroptosis, and a unique iron-dependent form of non-apoptotic cell death, called ferroptosis, is implicated in the pathogenesis of COPD. Iron metabolism plays a key role in producing reactive oxygen species (ROS), including mitochondrial ROS and lipid peroxidation end-products, and activating both necroptosis and ferroptosis. This review outlines recent studies exploring CS-mediated iron metabolism and ROS production, along with the regulation of programmed cell death in COPD. Elucidating the mechanisms of these pathways may provide novel therapeutic targets for COPD.

Reactive Oxygen Species and Antioxidative Defense in Chronic Obstructive Pulmonary Disease

The respiratory system is continuously exposed to endogenous and exogenous oxidants. Chronic obstructive pulmonary disease (COPD) is characterized by chronic inflammation of the airways, leading to the destruction of lung parenchyma (emphysema) and declining pulmonary function. It is increasingly obvious that reactive oxygen species (ROS) and reactive nitrogen species (RNS) contribute to the progression and amplification of the inflammatory responses related to this disease. First, we described the association between cigarette smoking, the most representative exogenous oxidant, and COPD and then presented the multiple pathophysiological aspects of ROS and antioxidative defense systems in the development and progression of COPD. Second, the relationship between nitric oxide system (endothelial) dysfunction and oxidative stress has been discussed. Third, we have provided data on the use of these biomarkers in the pathogenetic mechanisms involved in COPD and its progression and presented an overview of oxidative stress biomarkers having clinical applications in respiratory medicine, including those in exhaled breath, as per recent observations. Finally, we explained the findings of recent clinical and experimental studies evaluating the efficacy of antioxidative interventions for COPD. Future breakthroughs in antioxidative therapy may provide a promising therapeutic strategy for the prevention and treatment of COPD.

Oxidative Stress Promotes Corticosteroid Insensitivity in Asthma and COPD

Corticosteroid insensitivity is a key characteristic of patients with severe asthma and COPD. These individuals experience greater pulmonary oxidative stress and inflammation, which contribute to diminished lung function and frequent exacerbations despite the often and prolonged use of systemic, high dose corticosteroids. Reactive oxygen and nitrogen species (RONS) promote corticosteroid insensitivity by disrupting glucocorticoid receptor (GR) signaling, leading to the sustained activation of pro-inflammatory pathways in immune and airway structural cells. Studies in asthma and COPD models suggest that corticosteroids need a balanced redox environment to be effective and to reduce airway inflammation. In this review, we discuss how oxidative stress contributes to corticosteroid insensitivity and the importance of optimizing endogenous antioxidant responses to enhance corticosteroid sensitivity. Future studies should aim to identify how antioxidant-based therapies can complement corticosteroids to reduce the need for prolonged high dose regimens in patients with severe asthma and COPD.

Oxidative Stress and Antioxidant Pathway in Allergic Rhinitis

Oxidative stress is the cause and consequence of redox metabolism in various physiological and pathological conditions. Understanding the molecular pathways underlying oxidative stress and the role of antioxidants could serve as the key to helping treat associated diseases. Allergic rhinitis is a condition that deteriorates the daily function and quality of life of afflicted individuals and is associated with a high socioeconomic burden and prevalence. Recent studies have focused on the role of oxidative stress and antioxidants in allergic rhinitis. This review discusses animal and clinical studies on oxidative markers and the potential therapeutic dietary antioxidants for allergic rhinitis.

Lycium barbarum polysaccharides attenuate cardiovascular oxidative stress injury by enhancing the Keap1/Nrf2 signaling pathway in exhaustive exercise rats

Moderate exercise is beneficial to physical and mental health. When the amount of exercise and exercise intensity exceeds a certain limit and reaches the state of exhaustion, oxidative stress levels in the body increase, which can lead to oxidative stress‑associated damage. Lycium barbarum polysaccharide (LBP) is one of the primary active ingredients extracted from wolfberry. Following exhausting exercise in rats, LBP supplements decrease damage to the myocardium and blood vessels, indicating that LBP exerts a protective effect on the cardiovascular system. The Kelch‑like ECH‑associated protein 1 (Keap1)/NF‑E2‑related factor 2 (Nrf2) anti‑oxidative stress signaling pathway improves total oxidizing ability; anti‑apoptosis and other aspects serve a vital role. In the present study, LBP intervention was performed in vivo and in vitro to observe its effect on the Keap1/Nrf2 pathway and oxidative stress‑associated indicators in order to clarify its protective mechanism. For the in vivo experiments, 60 male Sprague‑Dawley rats were randomly divided into normal control and aerobic, exhaustive and exhaustive exercise + LBP (200 mg/kg/day) groups. For the in vitro experiments, a rat thoracic aortic endothelial cell (RTAEC) oxidative stress model was established using angiotensin II (AngII) and divided into blank control, LBP (3,200 µg/ml), AngII (1x10^‑4 mol/l) and AngII + LBP groups. For in vitro experiments, small interfering (si)RNA (50 nmol) was used to transfect RTAEC and induce gene silencing of Nrf2. ELISA, hematoxylin and eosin staining, TUNEL, immunofluorescence, western blotting, immunohistochemistry and reverse transcription‑quantitative PCR were used to evaluate and verify the effect of LBP on oxidative stress indicators and the expression of Keap1/Nrf2 antioxidative stress signaling pathway. The in vivo experiments showed that LBP decreased the expression of serum malondialdehyde (MDA) and AngII, as well as apoptosis of blood vessels and cardiomyocytes and expression of TNF‑α in rats following exhaustive exercise. Meanwhile, LBP enhanced expression of the Keap1/Nrf2 signaling pathway and downstream associated protein glutamyl‑cysteine synthetase catalytic subunit (GCLC), quinone oxidoreductase 1 (NQO1) and glutamate‑cysteine ligase modified subunit (GCLM) in the thoracic aorta and myocardium of rats following exhaustive exercise. In RTAEC in vitro, LBP decreased the expression of MDA and TNF‑α in the supernatant, promoted the nuclear translocation of Nrf2 and increased expression levels of GCLC, NQO1 and GCLM. Following siNrf2 transfection into endothelial cells, the anti‑inflammatory and antioxidant stress effects of LBP were decreased. LBP was found to enhance the expression of the Keap1/Nrf2 antioxidant stress signaling pathway in endothelial cells, decreasing oxidative stress and the inflammatory response. Moreover, LBP improved the antioxidant stress ability of endothelial cells and alleviated injury of myocardial vascular tissue, thereby protecting the cardiovascular system.

Diagnostic and Prognostic Significance of Keap1 mRNA Expression for Lung Cancer Based on Microarray and Clinical Information from Oncomine Database

We performed a bioinformatics analysis with validation by multiple databases, aiming to evaluate the diagnostic and prognostic value of Kelch-like ECH-associated protein 1 (Keap1) mRNA for lung cancer, and to explore possible mechanisms. Diagnostic performance of Keap1 mRNA was determined by receiver operating characteristic (ROC) curve analysis. Prognostic implication of Keap1 mRNA was estimated by Kaplan-Meier survival analysis. Co-expressed genes with both Keap1 and Nfe2L2 were identified by LinkedOmics. Mechanisms of Keap1-Nfe2L2-co-expressed genes underlying the pathogenesis of lung cancer were explored by function enrichment and pathway analysis. The ROC curve analysis determined a good diagnostic performance of Keap1 mRNA for lung squamous cell carcinoma (LUSC), with an area under the ROC curve (AUC) of 0.833, sensitivity of 72.7%, and specificity of 90.6% (P<0.001). Multivariate Cox regression recognized high Keap1 mRNA to be an independent risk factor of mortality for overall lung cancer [hazard ratio (HR): 11.034, P=0.044], but an independent antagonistic factor for lung adenocarcinoma (LUAD) (HR: 0.404, P<0.001). Validation by UALCAN and GEPIA supported Oncomine findings regarding the diagnostic value of Keap1 mRNA for LUSC, but denied its prognostic value. After screening, we identified 17 co-expressed genes with both Keap1 and Nfe2L2 for LUAD, and 22 for LUSC, mainly enriched in signaling pathway of oxidative stress-induced gene expression via Nrf2. In conclusion, Keap1 mRNA has a good diagnostic performance, but controversial prognostic efficacy for LUSC. The pathogenesis of lung cancer is associated with Keap1-Nfe2L2-co-expressed genes by signaling pathway of oxidative stress-induced gene expression via Nrf2.

miR-380-5p facilitates NRF2 and attenuates cerebral ischemia/reperfusion injury-induced neuronal cell death by directly targeting BACH1

Background

This study aimed to explore the role of miR-380-5p in cerebral ischemia/reperfusion (CIR) injury-induced neuronal cell death and the potential signaling pathway involved.

Methodology

Human neuroblastoma cell line SH-SY5Y cells were used in this study. Oxygen and glucose deprivation/reperfusion (OGD/R) model was used to mimic ischemia/reperfusion injury. CCK-8 assay and flow cytometry were used to examine cell survival. Quantitative real time PCR (RT-qPCR) assay and Western blotting were used to measure the change of RNA and protein expression, respectively. TargetScan and Luciferase assay was used to confirm the target of miR-380-5p. Malondialdehyde (MDA) superoxide dismutase (SOD) and glutathione peroxidase (GSHPx) were measured using commercial kits.

Results

miR-380-5p was downregulated in SH-SY5Y cells after OGD/R. Cell viability was increased by miR-380-5p, while cell apoptosis was reduced by miR-380-5p mimics. MDA was reduced by miR-380-5p mimics, while SOD and GSHPx were increased by miR-380-5p. Results of TargetScan and luciferase assay have showed that BACH1 is the direct target of miR-380-5p. Expression of NRF2 was upregulated after OGD/R, but was not affected by miR-380-5p. mRNA expression of HO-1 and NQO1 and ARE activity were increased by miR-380-5p. Overexpression of BACH1 reversed the antioxidant and neuroprotective effects of miR-380-5p.

Conclusion

miR-380-5p inhibited cell death induced by CIR injury through target BACH1 which also facilitated the activation of NRF2, indicating the antioxidant and neuroprotective effects of miR-380-5p.

Identification of novel inhibitors of Keap1/Nrf2 by a promising method combining protein-protein interaction-oriented library and machine learning

Protein–protein interactions (PPIs) are prospective but challenging targets for drug discovery, because screening using traditional small-molecule libraries often fails to identify hits. Recently, we developed a PPI-oriented library comprising 12,593 small-to-medium-sized newly synthesized molecules. This study validates a promising combined method using PPI-oriented library and ligand-based virtual screening (LBVS) to discover novel PPI inhibitory compounds for Kelch-like ECH-associated protein 1 (Keap1) and nuclear factor erythroid 2-related factor 2 (Nrf2). We performed LBVS with two random forest models against our PPI library and the following time-resolved fluorescence resonance energy transfer (TR-FRET) assays of 620 compounds identified 15 specific hit compounds. The high hit rates for the entire PPI library (estimated 0.56–1.3%) and the LBVS (maximum 5.4%) compared to a conventional screening library showed the utility of the library and the efficiency of LBVS. All the hit compounds possessed novel structures with Tanimoto similarity ≤ 0.26 to known Keap1/Nrf2 inhibitors and aqueous solubility (AlogP < 5). Reasonable binding modes were predicted using 3D alignment of five hit compounds and a Keap1/Nrf2 peptide crystal structure. Our results represent a new, efficient method combining the PPI library and LBVS to identify novel PPI inhibitory ligands with expanded chemical space.

Nrf2 signaling pathway in cisplatin chemotherapy: Potential involvement in organ protection and chemoresistance

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a vital transcription factor and its induction is of significant importance for protecting against oxidative damage. Increased levels of Reactive Oxygen Species (ROS) stimulate Nrf2 signaling, enhancing the activity of antioxidant enzymes such as catalase, superoxide dismutase and glutathione peroxidase. These enzymes are associated with retarding oxidative stress. On the other hand, Nrf2 activation in cancer cells is responsible for the development of chemoresistance due to disrupting oxidative mediated-cell death by reducing ROS levels. Cisplatin (CP), cis-diamminedichloroplatinum(II), is a potent anti-tumor agent extensively used in cancer therapy, but its frequent application leads to the development of chemoresistance as well. In the present study, association of Nrf2 signaling with chemoresistance to CP and protection against its deleterious effects is discussed. Anti-tumor compounds, mainly phytochemicals, retard chemoresistance by suppressing Nrf2 signaling. Upstream mediators such as microRNAs can regulate Nrf2 expression during CP chemotherapy regimens. Protection against side effects of CP is mediated via activating Nrf2 signaling and its downstream targets activating antioxidant defense system. Protective agents that activate Nrf2 signaling, can ameliorate CP-mediated ototoxicity, nephrotoxicity and neurotoxicity. Reducing ROS levels and preventing cell death are the most important factors involved in alleviating CP toxicity upon Nrf2 activation. As pre-clinical experiments advocate the role of Nrf2 in chemoprotection and CP resistance, translating these findings to the clinic can provide a significant progress in treatment of cancer patients.

The effect of Co-Q10 on allergic rhinitis and allergic asthma

Background

Allergic asthma is an inflammatory disease resulting from continued or intermittent allergen exposure, and allergic rhinitis can be trigger of asthma. The main mechanism of these disease is allergic reaction and immune response dysregulation. Co-Q10 is an enzyme cofactor in mitochondria can control asthma and allergic rhinitis symptoms. In the present study, we determined that the CoQ10-induced anti-allergic effects were mediated by up-regulation of Nrf2.

Methods

Animal models of allergic rhinitis and allergic asthma were produced and treated with Co-Q10, Co-Q10 and O-3, Co-Q10 and Mg-S. Bronchoalveolar lavage fluid was collected from animal models, and IL-4, 5, 13, INF-y, Eicosanoids, IgE, EPO, and histamine production were measured. Also, COX-2, CCL24, CCL11, Nrf2, Eotaxin, Cytb, COX1 and ND1 genes expressions and histopathology were studied. BALf's cells were collected by tracheostomy and used in slide producing by cytospine. Cytokines, Eicosanoids, IgE, EPO, and histamine were measured by ELISA method. Gene expression was done by Real-time PCR.

Results

Co-Q10 with two supplementation (Mg-S and O-3) modulate MRC, BALf eosinophils, eosinophilic inflammation related genes (eotaxin, CCL11 and CCL24), peribronchial and perivascular inflammation, EPO, type 2 cytokines (IL-4, 5 and 13), IgE, histamine, Cyc-LT and LTB4 as main allergic bio-factors. Importantly, Co-Q10 treatment increased Nrf2 expression and Nrf2 induced antioxidant genes, glutathione redox and inhibited inflammation, oxidative stress injury, Th2 cytokines production and attenuated allergic inflammatory responses.

Conclusion

Nrf2 is activated in response to allergen, induces resistance against the rhinitis and asthma development and plays an essential role in broncho-protection. Co-Q10 increases the Nrf2 expression and the Nrf2 over-expression has strong effect in control of type2 cytokines, allergic mediators and inflammatory factors that lead to harnessing of allergy and asthma.

Graphic abstract

Oxidative Imbalance as a Crucial Factor in Inflammatory Lung Diseases: Could Antioxidant Treatment Constitute a New Therapeutic Strategy?

Inflammatory lung disease results in a high global burden of death and disability. There are no effective treatments for the most severe forms of many inflammatory lung diseases, such as chronic obstructive pulmonary disease, emphysema, corticosteroid-resistant asthma, and coronavirus disease 2019; hence, new treatment options are required. Here, we review the role of oxidative imbalance in the development of difficult-to-treat inflammatory lung diseases. The inflammation-induced overproduction of reactive oxygen species (ROS) means that endogenous antioxidants may not be sufficient to prevent oxidative damage, resulting in an oxidative imbalance in the lung. In turn, intracellular signaling events trigger the production of proinflammatory mediators that perpetuate and aggravate the inflammatory response and may lead to tissue damage. The production of high levels of ROS in inflammatory lung diseases can induce the phosphorylation of mitogen-activated protein kinases, the inactivation of phosphoinositide 3-kinase (PI3K) signaling and histone deacetylase 2, a decrease in glucocorticoid binding to its receptor, and thus resistance to glucocorticoid treatment. Hence, antioxidant treatment might be a therapeutic option for inflammatory lung diseases. Preclinical studies have shown that antioxidants (alone or combined with anti-inflammatory drugs) are effective in the treatment of inflammatory lung diseases, although the clinical evidence of efficacy is weaker. Despite the high level of evidence for the efficacy of antioxidants in the treatment of inflammatory lung diseases, the discovery and clinical investigation of safer, more efficacious compounds are now a priority.

DJ-1 modulates Nrf2-mediated MRP1 expression by activating Wnt3a/β-catenin signalling in A549 cells exposed to cigarette smoke extract and LPS

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is an inflammatory disease characterized by airway obstruction and abnormal inflammatory responses. Multidrug resistance-related protein 1 (MRP1) can reduce lung inflammation and damage by excreting various toxic exogenous substances and certain pro-inflammatory molecules.

AIMS

We studied whether DJ-1 modulates nuclear factor erythroid 2-related factor 2 (Nrf2) by activating the Wnt3a/β-catenin signalling pathway to further regulate MRP1 expression and pulmonary antioxidant defences in alveolar epithelial (A549) cells treated with smoke extract (CSE) and lipopolysaccharide (LPS).

MAIN METHODS

Marker expression was studied by western blot analysis, quantitative real-time PCR and immunofluorescence staining of A549 cells.

KEY FINDINGS

A549 cells exposed to CSE and LPS showed downregulation of DJ-1, Wnt3a, MRP1 and haem oxygenase-1 (HO-1) and upregulation of inflammatory factors. Additionally, Nrf2 protein levels were significantly decreased, while there was no change in Nrf2 mRNA levels. Overexpression of DJ-1 and Wnt3a activated Nrf2 signalling, increased MRP1 and HO-1 levels and decreased IL-6 protein expression, while knockdown of DJ-1 and Wnt3a had the opposite effects. Furthermore, DJ-1 overexpression and DJ-1 knockdown increased and decreased, respectively, the levels of Wnt3a and β-catenin. Interestingly, Nrf2 and Wnt3a deficiency reduced the protective effects of Wnt3a and DJ-1, respectively, in A549 cells. However, the levels of DJ-1 and Wnt3a were not altered by Wnt3a and Nrf2 deletion, respectively.

SIGNIFICANCE

In A549 cells treated with CSE and LPS, DJ-1 regulates Nrf2-mediated MRP1 expression and antioxidant defences by activating the Wnt3a/β-catenin signalling pathway. These findings may provide potential therapeutic targets for COPD intervention.

Correlations among Pulmonary DJ-1, VDR and Nrf-2 in patients with Chronic Obstructive Pulmonary Disease: A Case-control Study

Parkinson protein 7 (PARK7)/DJ-1 (DJ-1) is a redox sensitive molecular and stabilizer of nuclear factor erythroid 2-related factor 2 (Nrf-2). Nrf-2 regulates the downstream antioxidant defense system and exerts a significant function in patients with chronic obstructive pulmonary disease (COPD). Vitamin D receptor (VDR) is the nuclear receptor that regulates the downstream target genes. This study aimed to analyze the associations among pulmonary function, DJ-1, VDR and Nrf-2 in COPD patients. Serum was collected from 180 COPD patients and control subjects. Thirty-five lung tissues were obtained. DJ-1 was measured using ELISA and western blotting. Nrf-2 and VDR were detected by immunohistochemistry. Serum and pulmonary DJ-1 levels were lower in COPD patients than those in control subjects. Pulmonary VDR-positive nuclei were reduced in COPD patients. Nrf-2-positive nuclei were reduced in lung tissues of COPD patients. On the contrary, Nrf-2-related downstream target proteins were elevated in COPD patients. Further correlation analysis indicated that forced expiratory volume in 1 second (FEV1) was positively associated with pulmonary DJ-1, VDR and Nrf-2 in patients with COPD. In addition, there were positive correlations among DJ-1, VDR and Nrf-2 in lung tissues of COPD patients. In conclusion, DJ-1, VDR and Nrf-2 were decreased in COPD patients compared with control subjects. The reduction of DJ-1 and VDR associating with Nrf-2 downregulation may be involved in the process of COPD.

Evaluation of Naringenin as a Promising Treatment Option for COPD Based on Literature Review and Network Pharmacology

Chronic obstructive pulmonary disease (COPD) is a chronic respiratory disease characterized by incompletely reversible airflow limitation and seriously threatens the health of humans due to its high morbidity and mortality. Naringenin, as a natural flavanone, has shown various potential pharmacological activities against multiple pathological stages of COPD, but available studies are scattered and unsystematic. Thus, we combined literature review with network pharmacology analysis to evaluate the potential therapeutic effects of naringenin on COPD and predict its underlying mechanisms, expecting to provide a promising tactic for clinical treatment of COPD.

Beneficial Effects of Naringenin in Cigarette Smoke-Induced Damage to the Lung Based on Bioinformatic Prediction and In Vitro Analysis

Naringenin is found mainly in citrus fruits, and is thought to be beneficial in the prevention and control of lung diseases. This study aims to investigate the mechanisms of naringenin against the damage in the lung caused by cigarette smoke. A system bioinformatic approach was proposed to predict the mechanisms of naringenin for protecting lung health. Then, we validated this prediction in BEAS-2B cells treated with cigarette smoke extract (CSE). System bioinformatic analysis indicated that naringenin exhibits protective effects on lung through the inhibition of inflammation and suppression of oxidative stress based on a multi-pathways network, mainly including oxidative stress pathway, Nrf2 pathway, Lung fibrosis pathway, IL-3 signaling pathway, and Aryl hydrocarbon receptor pathway. The in vitro results showed that naringenin significantly attenuated CSE-induced up-regulation of IL-8 and TNF-α. CSE stimulation increased the mRNA expressions of Nrf2, HO-1, and NQO1; the levels of total protein and nuclear protein of Nrf2; and the activity of SOD on days 2 and 4; but decreased these indexes on day 6. Naringenin can balance the antioxidant system by regulating Nrf2 and its downstream genes, preliminarily validating that Nrf2 pathway is involved in the protection offered by naringenin against cigarette smoke-induced damage to the lung. It suggests that dietary naringenin shows possible potential use in the management of lung health.

Total Antioxidant Status in Stable Chronic Obstructive Pulmonary Disease

Objective

This study evaluates the total antioxidant status (TAS) in plasma of stable chronic obstructive pulmonary disease (COPD) patients. Earlier studies of their relationship showed inconsistent findings.

Patients and Methods

We compared TAS between 90 COPD patients and 30 age- and sex-matched controls (mean age 67 ± 7.9, 87 males and 33 females) according to airway obstruction severity, gender, smoking status (current/ former/ non-smoker), smoking-dose, the number of exacerbations in the previous year, nutritional status and hypercapnia.

Results

There were no differences in pack-years between COPD and controls, neither in COPD groups. The median time from the last exacerbation was 5 months (interquartile range 3-8.3). TAS was significant higher in COPD than controls (1.68 [1.55-1.80] versus 1.59 [1.54-1.68], respectively; P = 0.03). TAS was significantly higher in COPD men than women (1.7 [1.6-1.8] versus 1.57 [1.5-1.7], respectively; P = 0.001). In COPD groups, there were no significant differences between the severity of airway obstruction and TAS. We found significant positive correlation between pack-years and TAS in all participants (Rho = 0.429, P = 0.004) and COPD patients (Rho = 0.359, P = 0.02), but not in controls. TAS was a significant predictor of COPD (β = 3.26; P = 0.04; OR = 26.01; 95% CI: 1.20 to 570.8). We failed to find significant differences between TAS and smoking status, frequency of exacerbations in the previous year, nutritional status and hypercapnia.

Conclusion

TAS was a significant predictor of COPD. TAS was a significantly higher in stable COPD than controls, higher in COPD men than women, but there was no significant correlation between TAS and the airway obstruction severity. Our results suggest that it could be appropriate to include the time from the last exacerbation in the oxidant-antioxidant balance analysis of COPD patients.

Epithelial Dysfunction in Lung Diseases: Effects of Amino Acids and Potential Mechanisms

Lung diseases affect millions of individuals all over the world. Various environmental factors, such as toxins, chemical pollutants, detergents, viruses, bacteria, microbial dysbiosis, and allergens, contribute to the development of respiratory disorders. Exposure to these factors activates stress responses in host cells and disrupt lung homeostasis, therefore leading to dysfunctional epithelial barriers. Despite significant advances in therapeutic treatments for lung diseases in the last two decades, novel interventional targets are imperative, considering the side effects and limited efficacy in patients treated with currently available drugs. Nutrients, such as amino acids (e.g., arginine, glutamine, glycine, proline, taurine, and tryptophan), peptides, and bioactive molecules, have attracted more and more attention due to their abilities to reduce oxidative stress, inhibit apoptosis, and regulate immune responses, thereby improving epithelial barriers. In this review, we summarize recent advances in amino acid metabolism in the lungs, as well as multifaceted functions of amino acids in attenuating inflammatory lung diseases based on data from studies with both human patients and animal models. The underlying mechanisms for the effects of physiological amino acids are likely complex and involve cell signaling, gene expression, and anti-oxidative reactions. The beneficial effects of amino acids are expected to improve the respiratory health and well-being of humans and other animals. Because viruses (e.g., coronavirus) and environmental pollutants (e.g., PM2.5 particles) induce severe damage to the lungs, it is important to determine whether dietary supplementation or intravenous administration of individual functional amino acids (e.g., arginine-HCl, citrulline, N-acetylcysteine, glutamine, glycine, proline and tryptophan) or their combinations to affected subjects may alleviate injury and dysfunction in this vital organ.