Effects of epigallocatechin-3-gallate on the HMGB1/RAGE pathway in PM2.5-exposed asthmatic rats

Phytochemical reduces toxicity of PM2.5: a review of research progress

Studies have shown that exposure to fine particulate matter (PM2.5) affects various cells, systems, and organs in vivo and in vitro. PM2.5 adversely affects human health through mechanisms such as oxidative stress, inflammatory response, autophagy, ferroptosis, and endoplasmic reticulum stress. Phytochemicals are of interest for their broad range of physiological activities and few side effects, and, in recent years, they have been widely used to mitigate the adverse effects caused by PM2.5 exposure. In this review, the roles of various phytochemicals are summarized, including those of polyphenols, carotenoids, organic sulfur compounds, and saponin compounds, in mitigating PM2.5-induced adverse reactions through different molecular mechanisms, including anti-inflammatory and antioxidant mechanisms, inhibition of endoplasmic reticulum stress and ferroptosis, and regulation of autophagy. These are useful as a scientific basis for the prevention and treatment of disease caused by PM2.5.

The Role of Eosinophil-Derived Neurotoxin and Vascular Endothelial Growth Factor in the Pathogenesis of Eosinophilic Asthma

Asthma is a chronic complex pulmonary disease characterized by airway inflammation, remodeling, and hyperresponsiveness. Vascular endothelial growth factor (VEGF) and eosinophil-derived neurotoxin (EDN) are two significant mediators involved in the pathophysiology of asthma. In asthma, VEGF and EDN levels are elevated and correlate with disease severity and airway hyperresponsiveness. Diversity in VEGF polymorphisms results in the variability of responses to glucocorticosteroids and leukotriene antagonist treatment. Targeting VEGF and eosinophils is a promising therapeutic approach for asthma. We identified lichochalcone A, bevacizumab, azithromycin (AZT), vitamin D, diosmetin, epigallocatechin gallate, IGFBP-3, Neovastat (AE-941), endostatin, PEDF, and melatonin as putative add-on drugs in asthma with anti-VEGF properties. Further studies and clinical trials are needed to evaluate the efficacy of those drugs. AZT reduces the exacerbation rate and may be considered in adults with persistent symptomatic asthma. However, the long-term effects of AZT on community microbial resistance require further investigation. Vitamin D supplementation may enhance corticosteroid responsiveness. Herein, anti-eosinophil drugs are reviewed. Among them are, e.g., anti-IL-5 (mepolizumab, reslizumab, and benralizumab), anti-IL-13 (lebrikizumab and tralokinumab), anti-IL-4 and anti-IL-13 (dupilumab), and anti-IgE (omalizumab) drugs. EDN over peripheral blood eosinophil count is recommended to monitor the asthma control status and to assess the efficacy of anti-IL-5 therapy in asthma.

Hypoxia modeling techniques: A review

Hypoxia is the main cause and effect of a large number of diseases, including the most recent one facing the world, the coronavirus disease (COVID-19). Hypoxia is divided into short-term, long-term, and periodic, it can be the result of diseases, climate change, or living and traveling in the high mountain regions of the world. Since each type of hypoxia can be a cause and a consequence of various physiological changes, the methods for modeling these hypoxias are also different. There are many techniques for modeling hypoxia under experimental conditions. The most common animal for modeling hypoxia is a rat. Hypoxia models (hypoxia simulations) in rats are a tool to study the effect of various conditions on the oxygen supply of the body. These models can provide a necessary information to understand hypoxia and also provide effective treatment, highlighting the importance of various reactions of the body to hypoxia. The main parameters when choosing a model should be reproducibility and the goal that the scientist wants to achieve. Hypoxia in rats can be reproduced both ways exogenously and endogenously. The reason for writing this review was the aim to systematize the models of rats available in the literature in order to facilitate their selection by scientists. The relative strengths and limitations of each model need to be identified and understood in order to evaluate the information obtained from these models and extrapolate these results to humans to develop the necessary generalizations. Despite these problems, animal models have been and remain vital to understanding the mechanisms involved in the development and progression of hypoxia. The eligibility criteria for the selected studies was a comprehensive review of the methods and results obtained from the studies. This made it possible to make generalizations and give recommendations on the application of these methods. The review will assist scientists in choosing an appropriate hypoxia simulation method, as well as assist in interpreting the results obtained with these methods.

Therapeutic Effects of Green Tea Polyphenol (‒)-Epigallocatechin-3-Gallate (EGCG) in Relation to Molecular Pathways Controlling Inflammation, Oxidative Stress, and Apoptosis

(‒)-Epigallocatechin-3-gallate (EGCG) is the most abundant polyphenol in green tea. Thanks to multiple interactions with cell surface receptors, intracellular signaling pathways, and nuclear transcription factors, EGCG possesses a wide variety of anti-inflammatory, antioxidant, antifibrotic, anti-remodelation, and tissue-protective properties which may be useful in the treatment of various diseases, particularly in cancer, and neurological, cardiovascular, respiratory, and metabolic disorders. This article reviews current information on the biological effects of EGCG in the above-mentioned disorders in relation to molecular pathways controlling inflammation, oxidative stress, and cell apoptosis.

Preventive Effect of Epigallocatechin Gallate, the Main Component of Green Tea, on Acute Lung Injury Caused by Air Pollutants

Reducing the health hazards caused by air pollution is a global challenge and is included in the Sustainable Development Goals. Air pollutants, such as PM_2.5, induce respiratory and cardiovascular disorders by causing various inflammatory responses via oxidative stress. Catechins and polyphenols, which are components of green tea, have various protective effects, owing to their antioxidant ability. The main catechin in green tea, epigallocatechin gallate (EGCG), is potentially effective against respiratory diseases, such as idiopathic pulmonary fibrosis and asthma, but its effectiveness against air-pollution-dependent lung injury has not yet been investigated. In this study, we examined the effect of EGCG on urban aerosol-induced acute lung injury in mice. Urban aerosol treatment caused increases in inflammatory cell counts, protein levels, and inflammatory cytokine expression in the lungs of ICR mice, but pretreatment with EGCG markedly suppressed these responses. Analyses of oxidative stress revealed that urban aerosol exposure enhanced reactive oxygen species (ROS) production and the formation of ROS-activated neutrophil extracellular traps (NETs) in the lungs of mice. However, ROS production and NETs formation were markedly suppressed by pretreating the mice with EGCG. Gallocatechin gallate (GCG), a heat-epimerized form of EGCG, also markedly suppressed urban aerosol-dependent inflammatory responses and ROS production in vivo and in vitro. These findings suggest that EGCG and GCG prevent acute lung injury caused by urban aerosols through their inhibitory effects on ROS production. Thus, we believe that foods and medications containing EGCG or GCG may be candidates to prevent the onset and progression of acute lung injury caused by air pollutants.

Selenium-enriched soybean peptides pretreatment attenuates lung injury in mice induced by fine particulate matters (PM2.5) through inhibition of TLR4/NF-κB/IκBα signaling pathway and inflammasome generation

This study aimed to identify and prepare peptides from selenium (Se)-enriched soybeans and determine whether dietary Se-enriched soybean peptides (Se-SPep) could inhibit lung injury in mice induced by fine particulate matter 2.5 (PM2.5). BALB/c mice were randomly divided into six groups. The mice in the prevention groups were pretreated with 378 mg kg^-1 of Se-SPep, soybean peptides (SPep), and Se-enriched soybean protein (Se-SPro), respectively, for four weeks. The mice in the PM2.5 exposure group received concentrated PM2.5 (15 μg per day mice) for 1 h daily from the third week for two weeks. The results showed that the leukocyte and cytokine (IL-1β, IL-6, TNF-α) levels in the bronchoalveolar lavage fluid (BALF) of the PM2.5 exposure group were higher than those in the control group. Se-SPep pretreatment decreased the IL-1β, IL-6, and TNF-α levels compared with the PM2.5 exposure group. Additionally, Se-SPep pretreatment inhibited TLR4/NF-κB/IκBα and NLRP3/ASC/caspase-1 protein expression in the lungs. In conclusion, Se-SPep pretreatment may protect the lungs of the mice against PM2.5-induced inflammation, suggesting that Se-SPep represents a potential preventative agent to inhibit PM2.5-induced lung injury.

Green Tea Polyphenol (-)-Epigallocatechin-3-Gallate (EGCG): A Time for a New Player in the Treatment of Respiratory Diseases?

(-)-Epigallocatechin-3-gallate (EGCG) is a major polyphenol of green tea that possesses a wide variety of actions. EGCG acts as a strong antioxidant which effectively scavenges reactive oxygen species (ROS), inhibits pro-oxidant enzymes including NADPH oxidase, activates antioxidant systems including superoxide dismutase, catalase, or glutathione, and reduces abundant production of nitric oxide metabolites by inducible nitric oxide synthase. ECGC also exerts potent anti-inflammatory, anti-fibrotic, pro-apoptotic, anti-tumorous, and metabolic effects via modulation of a variety of intracellular signaling cascades. Based on this knowledge, the use of EGCG could be of benefit in respiratory diseases with acute or chronic inflammatory, oxidative, and fibrotizing processes in their pathogenesis. This article reviews current information on the biological effects of EGCG in those respiratory diseases or animal models in which EGCG has been administered, i.e., acute respiratory distress syndrome, respiratory infections, COVID-19, bronchial asthma, chronic obstructive pulmonary disease, lung fibrosis, silicosis, lung cancer, pulmonary hypertension, and lung embolism, and critically discusses effectiveness of EGCG administration in these respiratory disorders. For this review, articles in English language from the PubMed database were used.

Food bioactives lowering risks of chronic diseases induced by fine particulate air pollution: a comprehensive review

Airborne particulate matter (PM) exerts huge negative impacts on human health worldwide, not only targeting the respiratory system but more importantly inducing and aggravating associated chronic diseases like asthma, lung cancer, atherosclerosis, diabetes mellitus and Alzheimer diseases. Food-derived bioactive compounds like vitamins, dietary polyphenols, omega-3 polyunsaturated fatty acids and sulforaphane are feasible alternative therapeutic approaches against PM-mediated potential health damages, drawing great attention in recent years. In this review, the association between PM exposure and risks of developing chronic diseases, and the detailed mechanisms underlying the detrimental effects of PM will be discussed. Subsequently, principal food-derived bioactive compounds, with emphasize on the preventative or protective effects against PM, along with potential mechanisms will be elucidated. This comprehensive review will discuss and present current research findings to reveal the nutritional intervention as a preventative or therapeutic strategy against ambient air pollution, thereby lowering the risk of developing chronic diseases.

Potential protective mechanisms of green tea polyphenol EGCG against COVID-19

Background

The world is in the midst of the COVID-19 pandemic. In this comprehensive review, we discuss the potential protective effects of (−)-epigallocatechin-3-gallate (EGCG), a major constituent of green tea, against COVID-19.

Scope and approach

Information from literature of clinical symptoms and molecular pathology of COVID-19 as well as relevant publications in which EGCG shows potential protective activities against COVID-19 is integrated and evaluated.

Key findings and conclusions

EGCG, via activating Nrf2, can suppress ACE2 (a cellular receptor for SARS-CoV-2) and TMPRSS2, which mediate cell entry of the virus. Through inhibition of SARS-CoV-2 main protease, EGCG may inhibit viral reproduction. EGCG via its broad antioxidant activity may protect against SARS-CoV-2 evoked mitochondrial ROS (which promote SARS-CoV-2 replication) and against ROS burst inflicted by neutrophil extracellular traps. By suppressing ER-resident GRP78 activity and expression, EGCG can potentially inhibit SARS-CoV-2 life cycle. EGCG also shows protective effects against 1) cytokine storm-associated acute lung injury/acute respiratory distress syndrome, 2) thrombosis via suppressing tissue factors and activating platelets, 3) sepsis by inactivating redox-sensitive HMGB1, and 4) lung fibrosis through augmenting Nrf2 and suppressing NF-κB. These activities remain to be further substantiated in animals and humans. The possible concerted actions of EGCG suggest the importance of further studies on the prevention and treatment of COVID-19 in humans. These results also call for epidemiological studies on potential preventive effects of green tea drinking on COVID-19.

(-)-Epigallocatechin-3-gallate inhibits RANKL-induced osteoclastogenesis via downregulation of NFATc1 and suppression of HO-1-HMGB1-RAGE pathway

Osteoporosis disturbs the balance of bone metabolism, and excessive bone resorption causes a decrease in bone density, thus increasing the risk of fracture. (-)-Epigallocatechin-3-gallate (EGCG) is the most abundant catechin contained in green tea. EGCG has a variety of pharmacological activities. Recently, it was reported that EGCG inhibits osteoclast differentiation, but the details of the mechanism underlying the EGCG-mediated suppression of osteoclastogenesis are unknown. In this study, we investigated the effects of EGCG on several signaling pathways in osteoclastogenesis. EGCG suppressed the expression of the nuclear factor of activated T cells cytoplasmic-1 (NFATc1), the master regulator of osteoclastogenesis. EGCG decreased the expression of cathepsin K, c-Src, and ATP6V0d2 and suppressed bone resorption. We also found that EGCG upregulated heme oxygenase-1 (HO-1) and suppressed the extracellular release of high-mobility group box 1 (HMGB1). In addition, EGCG decreased the expression of the receptor for advanced glycation end products (RAGE), which is the receptor of HMGB1, in osteoclastogenesis. In summary, our study showed that EGCG could inhibit osteoclast differentiation through the downregulation of NFATc1 and the suppression of the HO-1-HMGB1-RAGE pathway. EGCG might have the potential to be a lead compound that suppresses bone resorption in the treatment of osteoporosis.

Epigallocatechin Gallate (EGCG) Improves Anti-Angiogenic State, Cell Viability, and Hypoxia-Induced Endothelial Dysfunction by Downregulating High Mobility Group Box 1 (HMGB1) in Preeclampsia

Background

Preeclampsia (PE) is a serious complication of pregnancy with no effective therapy. This study assessed whether epigallocatechin gallate (EGCG) could reduce the production of anti-angiogenic factors, improve cell viability, and suppress endothelial dysfunction in vitro via regulating high mobility group box 1 (HMGB1) in preeclampsia.

Material/Methods

Human umbilical vein endothelial cells (HUVECs) grown in conditioned medium from hypoxic JEG-3 cells were used to investigate the effects of EGCG on anti-angiogenic state, cell viability, and markers of endothelial dysfunction. To confirm that EGCG exerted its effects via HMGB1, we also examined the impact of EGCG on anti-angiogenic state, cell viability, and endothelial dysfunction following HMGB1 treatment in vitro.

Results

EGCG inhibited HMGB1 expression in hypoxic trophoblast cells in a dose-dependent manner. In addition, EGCG relieved anti-angiogenic state and endothelial dysfunction in hypoxic trophoblast cells by downregulating HMGB1. Moreover, EGCG dose-dependently promoted cell proliferation by downregulating HMGB1.

Conclusions

Taken together, our data show the protective role of EGCG in preeclampsia and revealed EGCG-mediated effects on the production of anti-angiogenic factors, cell viability, and endothelial dysfunction through downregulating HMGB1. These observations suggest that EGCG is a novel therapeutic candidate for preeclampsia.

An overview of high-mobility group box 1, a potent pro-inflammatory cytokine in asthma

High-mobility group box 1 (HMGB1), also called amphoterin, HMG1 and p30, is a highly conserved protein between different species that has various functions in nucleus such as stabilization of nucleosome formation, facilitation of deoxyribonucleic acid (DNA) bending and increasing the DNA transcription, replication and repair. It has also been indicated that HMGB1 acts as a potent pro-inflammatory cytokine with increasing concentrations in acute and chronic inflammatory diseases. Asthma is a common chronic respiratory disease associated with high morbidity and mortality rates. One central characteristic in its pathogenesis is airway inflammation. Considering the inflammatory role of HMGB1 and importance of inflammation in asthma pathogenesis, a better understanding of this protein is vital. This review describes the structure, cell surface receptors, signaling pathways and intracellular and extracellular functions of HMGB1, but also focuses on its inflammatory role in asthma. Moreover, this manuscript reviews experimental and clinical studies that investigated the pathologic role of HMGB1.

Development and Characterization of an Allergic Asthma Rat Model for Interventional Studies

Allergic asthma is one of the most common chronic diseases of the airways, however it still remains underdiagnosed and hence undertreated. Therefore, an allergic asthma rat model would be useful to be applied in future therapeutic strategy studies. The aim of the present study was to develop an objective model of allergic asthma in atopic rats that allows the induction and quantification of anaphylactic shock with quantitative variables. Female Brown Norway rats were intraperitoneally sensitized with ovalbumin (OVA), alum and Bordetella pertussis toxin and boosted a week later with OVA in alum. At day 28, all rats received an intranasal challenge with OVA. Anaphylactic response was accurately assessed by changes in motor activity and body temperature. Leukotriene concentration was determined in the bronchoalveolar lavage fluid (BALF), and total and IgE anti-OVA antibodies were quantified in blood and BALF samples. The asthmatic animals' motility and body temperature were reduced after the shock for at least 20 h. The asthmatic animals developed anti-OVA IgE antibodies both in BALF and in serum. These results show an effective and relatively rapid model of allergic asthma in female Brown Norway rats that allows the quantification of the anaphylactic response.