Therapeutic potential of bixin in PM2.5 particles-induced lung injury in an Nrf2-dependent manner

Pharmacotherapeutic Strategies for Fine Particulate Matter-Induced Lung and Cardiovascular Damage: Marketed Drugs, Traditional Chinese Medicine, and Biological Agents

Fine particulate matter (PM2.5), defined as airborne particles with a diameter of ≤ 2.5 μm, represents a major constituent of air pollution and has been globally implicated in exacerbating public health burdens by elevating morbidity and mortality rates associated with respiratory and cardiovascular diseases (CVDs). Adverse health effects of PM2.5 exposure manifest across diverse susceptibility profiles and durations of exposure, spanning both acute and chronic timelines. While prior reviews have predominantly focused on elucidating the toxicological mechanisms underlying PM2.5-induced pathologies, there remains a paucity of comprehensive summaries addressing therapeutic interventions for cardiopulmonary damage. This review systematically synthesizes pharmacological agents with potential therapeutic efficacy against PM2.5-induced pulmonary and cardiovascular injury. By integrating mechanistic insights with translational perspectives, this work aims to provide a foundational framework for advancing research into novel therapeutic strategies targeting PM2.5-associated cardiopulmonary disorders.

Metallothionein, an endogenous antioxidant protein, protects against acute lung injury caused by air pollutants

Reducing deaths and diseases due to air pollution is a global challenge enshrined in the Sustainable Development Goals. Currently, there is an urgent need to discover factors that protect the lungs and bronchi, which are the first to be injured and undergo oxidative stress when air pollutants enter the body, and to establish methods to prevent their onset and progression. Metallothionein, a protein present in humans that exerts detoxification and antioxidant effects on toxic metals, has long been known to exert protective effects against liver and kidney diseases. However, no functional analysis of the effects of metallothionein on acute lung injury caused by air pollutants has been reported. Thus, we studied the effect of metallothionein on urban aerosol-dependent acute lung injury using metallothionein knockout (MT-KO) mice and a metallothionein inducer. Most importantly, we found that urban aerosol-dependent acute lung injury was exacerbated in MT-KO mice compared to wild-type (WT) mice. In addition, inflammatory responses and reactive oxygen species production in the lungs were enhanced in MT-KO mice compared to WT mice. Furthermore, we found that the intraperitoneal administration of zinc acetate exerted an antioxidant effect via the induction of metallothionein providing a protective effect against the development of urban aerosol-dependent acute lung injury. These results suggest that the metallothionein protein itself or compounds with metallothionein-inducing action may help prevent acute lung injury caused by air pollutants.

Macrophage pyroptosis and its crucial role in ALI/ARDS

Acute lung injury(ALI)/acute respiratory distress syndrome(ARDS) is a severe clinical syndrome characterized by high morbidity and mortality, primarily due to lung injury. However, the pathogenesis of ALI/ARDS remains a complex issue. In recent years, the role of macrophage pyroptosis in lung injury has garnered extensive attention worldwide. This paper reviews the mechanism of macrophage pyroptosis, discusses its role in ALI/ARDS, and introduces several drugs and intervening measures that can regulate macrophage pyroptosis to influence the progression of ALI/ARDS. By doing so, we aim to enhance the understanding of the mechanism of macrophage pyroptosis in ALI/ARDS and provide novel insights for its treatment.

Ambient fine particulate matter provokes multiple modalities of cell death via perturbation of subcellular structures

Fine particulate matter (PM2.5) is increasingly recognized for its detrimental effects on human health, with substantial evidence linking exposure to various forms of cell death and dysfunction across multiple organ systems. This review examines key cell death mechanisms triggered by PM2.5, including PANoptosis, necroptosis, autophagy, and ferroptosis, while other forms such as oncosis, paraptosis, and cuprotosis remain unreported in relation to PM2.5 exposure. Mitochondria, endoplasmic reticulum, and lysosomes emerge as pivotal organelles in the disruption of cellular homeostasis, with mitochondrial dysfunction particularly implicated in metabolic dysregulation and the activation of pro-apoptotic pathways. Although PM2.5 primarily affects the nucleus, cytoskeleton, mitochondria, endoplasmic reticulum, and lysosomes, other organelles like ribosomes, Golgi apparatus, and peroxisomes have received limited attention. Interactions between these organelles, such as endoplasmic reticulum-associated mitochondrial membranes, lysosome-associated mitophagy, and mitochondria-nuclei retro-signaling may significantly contribute to the cytotoxic effects of PM2.5. The mechanisms of PM2.5 toxicity, encompassing oxidative stress, inflammatory responses, and metabolic imbalances, are described in detail. Notably, PM2.5 activates the NLRP3 inflammasome, amplifying inflammatory responses and contributing to chronic diseases. Furthermore, PM2.5 exposure disrupts genetic and epigenetic regulation, often resulting in cell cycle arrest and exacerbating cellular damage. The composition, concentration, and seasonal variability of PM2.5 modulate these effects, underscoring the complexity of PM2.5-induced cellular dysfunction. Despite significant advances in understanding these pathways, further research is required to elucidate the long-term effects of chronic PM2.5 exposure, the role of epigenetic regulation, and potential strategies to mitigate its harmful impact on human health.

Vitamins, Minerals and Phytonutrients as Modulators of Canine Immune Function: A Literature Review

Trends in the pet food industry are driven by the humanization of pets, favoring the inclusion of functional ingredients or supplements that promote animal health. Several commercial diets claim to include supplements with benefits for dogs' immune function, but in vivo evidence that supports their efficacy remains limited. This literature review aimed to better understand the current knowledge on the effects of vitamins, minerals and phytonutrients on dogs' immune function. A total of 27 peer-reviewed articles were identified in PubMed and Web of Science databases. Although vitamin supplementation is often claimed to support immune function, only two studies promoting slight benefits of vitamins C and E were found. The limited research on minerals suggests that organic sources promote a better immune response. Studies evaluating the inclusion of different phytonutrients show that these compounds might exert immunomodulatory and anti-inflammatory effects. Despite the increased popularity of commercial diets claimed to support the immune response of dogs, further research is needed in order to substantiate their effects. This knowledge will contribute to the development of effective diets to enhance immune health in dogs.

Effect of the Structural Modification of Plant Proteins as Microencapsulating Agents of Bioactive Compounds from Annatto Seeds (Bixa orellana L.)

This project studied the use of lentil protein (LP) and quinoa protein (QP) in their native and modified states as carrier material in the encapsulation process by the ionic gelation technique of annatto seed extract. Soy protein (SP) was used as a model of carrier material and encapsulated bioactive compounds, respectively. The plant proteins were modified by enzymatic hydrolysis, N acylation, and N-cationization to improve their encapsulating properties. Additionally, the secondary structure, differential scanning calorimetry (DSC), solubility as a function of pH, isoelectric point (pI), molecular weight (MW), the content of free thiol groups (SH), the absorption capacity of water (WHC) and fat (FAC), emulsifier activity (EAI), emulsifier stability (ESI), and gelation temperature (Tg) were assessed on proteins in native and modified states. The results obtained demonstrated that in a native state, LP (80.52% and 63.82%) showed higher encapsulation efficiency than QP (73.63% and 45.77%), both for the hydrophilic dye and for the annatto extract. Structural modifications on proteins improve some functional properties, such as solubility, WHC, FAC, EAI, and ESI. However, enzymatic hydrolysis on the proteins decreased the gels' formation, the annatto extract's encapsulated efficiency, and the hydrophilic dye by the ionic gelation method. On the other hand, the modifications of N-acylation and N-cationization increased but did not generate statistically significant differences (p-value > 0.05) in the encapsulation efficiency of both the annatto extract and the hydrophilic dye compared to those obtained with native proteins. This research contributes to understanding how plant proteins (LP and QP) can be modified to enhance their encapsulating and solubility properties. The better encapsulation of bioactive compounds (like annatto extract) can improve product self-life, potentially benefiting the development of functional ingredients for the food industry.

Paeoniflorin attenuates particulate matter-induced acute lung injury by inhibiting oxidative stress and NLRP3 inflammasome-mediated pyroptosis through activation of the Nrf2 signaling pathway

Particulate matter (PM), the main component of air pollutants, emerges as a research hotspot, especially in the area of respiratory diseases. Paeoniflorin (PAE), known as anti-inflammatory and immunomodulatory effects, has been reported to alleviate acute lung injury (ALI). However, the effect of PAE on PM-induced ALI and the underlying mechanisms are still unclear yet. In this study, we established the PM-induced ALI model using C57BL/6J mice and BEAS-2B cells to explore the function of PAE. In vivo, mice were intraperitoneally injected with PAE (100 mg/kg) or saline 1 h before instilled with 4 mg/kg PM intratracheally and were euthanized on the third day. For lung tissues, HE staining and TUNEL staining were used to evaluate the degree of lung injury, ELISA assay was used to assess inflammatory mediators and oxidative stress level, Immunofluorescence staining and western blotting were applied to explore the role of pyroptosis and Nrf2 signaling pathway. In vitro, BEAS-2B cells were pretreated with 100 μM PAE before exposure to 200 μg/ml PM and were collected after 24h for the subsequent experiments. TUNEL staining, ROS staining, and western blotting were conducted to explore the underlying mechanisms of PAE on PM-induced ALI. According to the results, PAE can attenuate the degree of PM-induced ALI in mice and reduce PM-induced cytotoxicity in BEAS-2B cells. PAE can relieve PM-induced excessive oxidative stress and NLRP3 inflammasome-mediated pyroptosis. Additionally, PAE can also activate Nrf2 signaling pathway and inhibition of Nrf2 signaling pathway can impair the protective effect of PAE by aggravating oxidative stress and pyroptosis. Our findings demonstrate that PAE can attenuate PM-induced ALI by inhibiting oxidative stress and NLRP3 inflammasome-mediated pyroptosis, which is mediated by Nrf2 signaling pathway.

Natural products as non-covalent and covalent modulators of the KEAP1/NRF2 pathway exerting antioxidant effects

By controlling several antioxidant and detoxifying genes at the transcriptional level, including NAD(P)H quinone oxidoreductase 1 (NQO1), multidrug resistance-associated proteins (MRPs), UDP-glucuronosyltransferase (UGT), glutamate-cysteine ligase catalytic (GCLC) and modifier (GCLM) subunits, glutathione S-transferase (GST), sulfiredoxin1 (SRXN1), and heme-oxygenase-1 (HMOX1), the KEAP1/NRF2 pathway plays a crucial role in the oxidative stress response. Accordingly, the discovery of modulators of this pathway, activating cellular signaling through NRF2, and targeting the antioxidant response element (ARE) genes is pivotal for the development of effective antioxidant agents. In this context, natural products could represent promising drug candidates for supplementation to provide antioxidant capacity to human cells. In recent decades, by coupling in silico and experimental methods, several natural products have been characterized to exert antioxidant effects by targeting the KEAP1/NRF2 pathway. In this review article, we analyze several natural products that were investigated experimentally and in silico for their ability to modulate KEAP1/NRF2 by non-covalent and covalent mechanisms. These latter represent the two main sections of this article. For each class of inhibitors, we reviewed their antioxidant effects and potential therapeutic applications, and where possible, we analyzed the structure-activity relationship (SAR). Moreover, the main computational techniques used for the most promising identified compounds are detailed in this survey, providing an updated view on the development of natural products as antioxidant agents.

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.

Oxidative stress is the pivot for PM2.5-induced lung injury

Fine particulate matter (PM2.5) is a primary air pollutant recognized worldwide as a serious threat to public health. PM2.5, which has a diameter of less than 2.5 μm, is known to cause various diseases, including cardiovascular, respiratory, metabolic, and neurological diseases. Studies have shown that the respiratory system is particularly susceptible to PM2.5 as it is the first line of defense against external pollutants. PM2.5 can cause oxidative stress, which is triggered by the catalyzation of biochemical reactions, the activation of oxidases and metabolic enzymes, and mitochondrial dysfunction, all of which can lead to lung injury and aggravate various respiratory diseases including chronic obstructive pulmonary disease (COPD), asthma, pulmonary fibrosis, and cancer. Oxidative stress plays a crucial role in the harmful effects and mechanisms of PM2.5 on the respiratory system by activating several detrimental pathways related to inflammation and cellular damage. However, experimental studies have shown that antioxidative therapy methods can effectively cure PM2.5-induced lung injury. This review aims to clarify how PM2.5 induces oxidative stress and the mechanisms by which it is involved in the aggravation of various lung diseases. Additionally, we have listed antioxidant treatments to protect against PM2.5-induced lung injury.

Paracrine signaling of ferroptotic airway epithelium in crystalline silica-induced pulmonary fibrosis augments local fibroblast activation through glycolysis reprogramming

Chronic exposure to crystalline silica (CS) contributes to pulmonary fibrosis. Airway epithelium dysfunction and fibroblast activation have both been recognized as pivotal players, alongside disturbances in ferroptosis and glycolysis reprogramming. However, the mechanisms involved remain unclear. In this study, we investigated the crosstalk between airway epithelium and fibroblast in the context of CS-induced pulmonary fibrosis. CS was employed in vivo and the in vitro co-culture system of airway epithelium and fibroblast. Spatial transcriptome analysis of CS-induced fibrotic lung tissue was conducted as well. Results showed that epithelium ferroptosis caused by CS enhanced TGFβ1-induced fibroblast activation through paracrine signaling. tPA was further identified to be the central mediator that bridges epithelium ferroptosis and fibroblast activation. And increased fibroblast glycolysis reprogramming was evidenced to promote fibroblast activation. By inhibition of epithelium ferroptosis or silencing tPA of airway epithelium, fibroblast AMPK phosphorylation was inhibited. Moreover, we revealed that tPA secreted by ferroptotic epithelium transmits paracrine signals to fibroblasts by governing glycolysis via p-AMPK/AMPK mediated Glut1 accumulation. Collectively, our study demonstrated the regulation of airway epithelium ferroptosis on fibroblast activation in CS-induced pulmonary fibrosis, which would shed light on the complex cellular crosstalk within pulmonary fibrosis and identify potential therapeutic targets.

Astaxanthin alleviates fine particulate matter (PM2.5)-induced lung injury in rats by suppressing ferroptosis and apoptosis

Objectives: Fine particulate matter (PM2.5), a small molecule particulate pollutant, can reach the lungs via respiration and cause lung damage. Currently, effective strategies and measures are lacking to prevent and treat the pulmonary toxicity of PM2.5. Astaxanthin (ASX), a natural xanthophyll carotenoid, has attracted attention due to its unique biological activity. Our research aims to probe into the prevention and treatment of ASX on PM2.5-induced lung injury and clarify its potential mechanism. Methods: Sprague-Dawley (SD) rats were given olive oil and different concentrations of ASX orally daily for 21 days. PM2.5 suspension was instilled into the trachea of rats every two days for one week to successfully develop the PM2.5 exposure model in the PM2.5-exposed and ASX-treated groups of rats. The bronchoalveolar lavage fluid (BALF) was collected, and the content of lung injury-related markers was detected. Histomorphological changes and expression of markers associated with oxidative stress, inflammation, iron death, and apoptosis were detected in lung tissue. Results: PM2.5 exposure can cause changes in lung histochemistry and increase the expression levels of TP, AKP, ALB, and LDH in the BALF. Simultaneously, inflammatory responses and oxidative stress were promoted in rat lung tissue after exposure to particulate matter. Additionally, ASX preconditioning can alleviate histomorphological changes, oxidative stress, and inflammation caused by PM2.5 and reduce PM2.5-related ferroptosis and apoptosis. Conclusion: ASX preconditioning can alleviate lung injury after PM2.5 exposure by inhibiting ferroptosis and apoptosis.

The role of bixin as antioxidant, anti-inflammatory, anticancer, and skin protecting natural product extracted from Bixa orellana L

Since long, medicinal plants or herbs are being used in different traditional treatment systems as therapeutic agents to treat a variety of illnesses. Bixa orellana L., an medicinal plant (family: Bixaceae), is an Ayurvedic herb used to treat dyslipidemia, diarrhoea, and hepatitis since ancient times. B. orellana L., seeds contain an orange-red coloured component known as bixin (C25H30O4), which constitutes 80% of the extract.Chemically, bixin is a natural apocarotenoid, biosynthesized through the oxidative degradation of C40 carotenoids. Bixin helps to regulate the Nrf2/MyD88/TLR4 and TGF-1/PPAR-/Smad3 pathways, which further give it antifibrosis, antioxidant, and anti-inflammatory properties. This current review article presents a comprehensive review of bixin as an anti-inflammatory, antioxidant, anticancer,and skin protecting natural product. In addition, the biosynthesis and molecular target of bixin, along with bixin extraction techniques, are also presented.

Rosavidin protects against PM2.5-induced lung toxicity via inhibition of NLRP3 inflammasome-mediated pyroptosis by activating the PI3K/AKT pathway

Fine particulate matter (PM2.5) contributes to adverse health effects through the promotion of inflammatory cytokine release. Rosavidin (Ro), a phenylpropanoid compound having multiple biological activities, is extracted from Rhodiola crenulata, a medicine and food homology plant. However, the protective role and mechanism of Ro in PM2.5-induced lung toxicity have not been previously studied. This study aimed to investigate the potential protective effect and mechanism of Ro in PM2.5-induced lung toxicity. A lung toxicity rat model was established through trachea drip of PM2.5 suspension after the different dose pretreatment of Ro (50 mg/kg and 100 mg/kg) to evaluate the effect of Ro on PM2.5 caused lung toxicity. The results showed that Ro attenuated the pathological changes, edema, and inflammation response in rats. The PI3K/AKT signaling pathway may be associated with the protective effect of Ro against pulmonary toxicity. Subsequently, we verified the role of PI3K/AKT in the PM2.5 exposure lung tissue. Moreover, expression levels of p-PI3K and p-AKT were lower, and those of NLRP3, ASC, cleaved caspase-1, cleaved IL-1β, and GSDMD-N were higher in PM2.5 group compared to those in control group. Whereas pre-administration of Ro reversed the expression trends of these proteins in lung tissue. Notably, those protective effects of Ro were not observed after pretreatment with a combination of Ro with nigericin or LY294002. These results indicate that Ro mitigates PM2.5-caused lung toxicity by inhibiting NLRP3 inflammasome-mediated pyroptosis through activation of the PI3K/AKT signaling pathway.

Bixin-loaded colloidal nanodelivery systems, techniques and applications

Bixin is the cis-carotenoid from the seed of achiote tree or annatto. It is an approved liposoluble apocarotenoid by FDA as colorant and additive in the food industry. Nonetheless, bixin is unstable in the presence of oxygen, light, high pHs (alkali) and heat; thereby reducing its bioavailability/bioactivity, and also, with a low solubility in water. Some biopolymeric (e.g., nanofibers, nanogels, and nanotubes) and lipid-based nanocarriers (nanoliposomes, niosomes, hexosomes, nanoemulsions, solid-lipid nanoparticles, and nanostructured lipid carriers) have been introduced for bixin. Thus, this review focuses on the updated information regarding bixin-loaded nanodelivery platforms. Moreover, it provides a comprehensive review of bioavailability, physicochemical properties, and applications of nanoencapsulated-bixin as an additive, its release rate and safety issues. These findings will bring potential strategies for the usage of nanocarriers in managing bixin defaults to improve its broad application in various industries.

N6-methyladenosine mediates Nrf2 protein expression involved in PM2.5-induced pulmonary fibrosis

It has been reported that particulate matter with an aerodynamic diameter of <2.5 µm (PM2.5) could induce epithelial-mesenchymal transition (EMT)- and extracellular matrix (ECM)-related pulmonary fibrosis (PF). The transcription factor Nrf2 alleviated PM2.5-induced PF by antagonizing oxidative stress. The N⁶-methyladenosine (m⁶A) modification plays a significant role in the stress response. However, the effect of m⁶A modification on the mechanisms of Nrf2-mediated defense against PM2.5-induced PF remained unknown. Here, we explored the role and the underlying molecular mechanisms of m⁶A methylation of Nrf2 mRNA in PM2.5-induced PF. We established filtered air (FA), unfiltered air (UA), and concentrated PM2.5 air (CA) group mice model and 0, 50, and 100 μg/mL PM2.5-treated 16HBE cell models. The extent of lung fibrosis in mice and fibrosis indicators were detected by histopathological analysis, immunohistochemical staining and western blotting. The molecular mechanism of m⁶A-modified Nrf2 was demonstrated by m⁶A-methylated RNA immunoprecipitation (MeRIP), RNA immunoprecipitation (RIP), qRT-PCR and T3 ligase-based PCR. Our data showed that PM2.5 exposure for 16 weeks could induce pulmonary fibrosis and activate Nrf2 signaling pathway. m⁶A methyltransferase METTL3 was upregulated after PM2.5 treatment in vivo and in vitro. Moreover, METTL3 mediated m⁶A modification of Nrf2 mRNA and promoted Nrf2 translation in mice and 16HBE cells after PM2.5 exposure. Mechanistically, three m⁶A-modified sites (1317, 1376 and 935; numbered relative to the first nucleotide of 3'UTR) of Nrf2 mRNA were identified in PM2.5-treatment 16HBE cells. Furthermore, the m⁶A binding proteins YTHDF1/IGF2BP1 promoted Nrf2 translation by binding to m⁶A residues of Nrf2 mRNA. Our results revealed the mechanism of m⁶A mediated Nrf2 signaling pathway against oxidative stress, which affected the development of PM2.5-induced PF.

Targeting NRF2 to promote epithelial repair

The transcription factor NRF2 is well known as a master regulator of the cellular stress response. As such, activation of NRF2 has gained widespread attention for its potential to prevent tissue injury, but also as a possible therapeutic approach to promote repair processes. While NRF2 activation affects most or even all cell types, its effect on epithelial cells during repair processes has been particularly well studied. In response to tissue injury, these cells proliferate, migrate and/or spread to effectively repair the damage. In this review, we discuss how NRF2 governs repair of epithelial tissues, and we highlight the increasing number of NRF2 targets with diverse roles in regulating epithelial repair.

Adverse effects of air pollution-derived fine particulate matter on cardiovascular homeostasis and disease

Air pollution is a rapidly growing major health concern around the world. Atmospheric particulate matter that has a diameter of less than 2.5 µm (PM2.5) refers to an air pollutant composed of particles and chemical compounds that originate from various sources. While epidemiological studies have established the association between PM2.5 exposure and cardiovascular diseases, the precise cellular and molecular mechanisms by which PM2.5 promotes cardiovascular complications are yet to be fully elucidated. In this review, we summarize the various sources of PM2.5, its components, and the concentrations of ambient PM2.5 in various settings. We discuss the experimental findings to date that evaluate the potential adverse effects of PM2.5 on cardiovascular homeostasis and function, and the possible therapeutic options that may alleviate PM2.5-driven cardiovascular damage.

Untapping the protective role of carotenoids against respiratory diseases

BACKGROUND

Recent studies revealed a substantial role of carotenoids to treat respiratory diseases. This review aimed to give an updated overview of the investigational evidence on the preventive properties of carotenoids against respiratory diseases both in vitro and in vivo along with their pathophysiology and mechanisms of action.

HYPOTHESIS

Carotenoids as a potential therapeutic class of bioactive compounds to treat respiratory diseases.

RESULTS

Carotenoids such as β-carotene, lycopene, crocin, bixin, lutein, and astaxanthin show beneficial effects against chronic lung diseases (e.g., asthma, emphysema, fibrosis, COPD, acute lung injury, and lung cancer). Moreover, in vitro and in vivo studies also supported the preventive role of carotenoids. These carotenoids showed a beneficial role by activation of the NRF2/HO-1 pathway and inhibition of the NF-кB, MAPK, JAK/STAT-3, and PI3K/AKT pathways. Additionally, epidemiological studies also showed that dietary intake of carotenoids lowers the risk of lung diseases.

CONCLUSION

Carotenoids may be used as drugs or can be given in combination with other drugs to prevent and treat respiratory diseases. Although in vitro and in vivo results are encouraging, further well-conducted randomized clinical trials are required to approve carotenoids as drug candidates.

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.

Astragaloside IV alleviates PM2.5-caused lung toxicity by inhibiting inflammasome-mediated pyroptosis via NLRP3/caspase-1 axis inhibition in mice

Exposure to particulate matter (PM)2.5 in air pollution is a serious health issue worldwide. At present, effective prevention measures and modalities of treatment for PM2.5-caused lung toxicity are lacking. This study elucidated the protective effect of astragaloside IV (Ast), a natural product from Astragalus membranaceous Bunge, against PM2.5-caused lung toxicity and its possible molecular mechanisms. The mice model of lung toxicity was performed by intratracheal instillation of PM2.5 dust suspension. The investigation was performed with Ast or in combination with nigericin, which is a NOD-like receptor protein 3 (NLRP3) activator. The results revealed that PM2.5 lead significant lung inflammation and promoted the pyroptosis pattern of cell death by upregulating pro-inflammatory cytokines and causing oxidative stress related to the NLRP3 inflammasome-mediated pyroptosis pathway. Ast protected against PM2.5 resulted lung toxicity via suppressing NLRP3 inflammasome-mediated pyroptosis via NLRP3/caspase-1 axis inhibition, thereby protecting the lung against PM2.5-induced lung inflammation and oxidative damage, eventually resulting in prolonged survival in mice. Nigericin partially reversed the protective effects of Ast. The present research provides new insights into the therapeutic potential of Ast, demonstrating that it might be a possible candidate for the prevention of PM2.5-caused respiratory diseases. Targeting the NLRP3 inflammasome might be a novel therapeutic tactic for PM2.5-caused respiratory diseases.

Study on Lung Injury Caused by Fine Particulate Matter and Intervention Effect of Rhodiola wallichiana

Objective

The objective of this study was to observe the protective effect of Rhodiola wallichiana drops in a rat model of fine particulate matter (PM2.5) lung injury.

Methods

Forty male Wistar rats were randomly divided into blank control (NC), normal saline (NS), PM2.5-infected (PM), and Rhodiola wallichiana (RW) groups. Rats in the NC group were not provided any interventions, whereas those in the NS and PM groups were administered normal saline and PM2.5 suspension by trachea drip once a week for four weeks. Rats in the RW group were intraperitoneally administered Rhodiola wallichiana for 14 days and then administered PM2.5 suspension by trachea drip 7 days after drug delivery. The levels of inflammatory factors such as interleukin-6, interleukin-1β, and tumor necrosis factor-alpha and oxidative stress biomarkers such as 8-hydroxy-2′-deoxyguanosine, 4-hydroxynonenal, and protein carbonyl content were determined in the serum and bronchoalveolar lavage fluid by ELISA. The level of 4-hydroxynonenal in the lung was also determined using Western blotting and immunohistochemical staining.

Results

Levels of inflammatory factors and oxidative stress biomarkers were all increased in the PM group but decreased in the RW group. Western blotting revealed increased 4-hydroxynonenal levels in the PM group but decreased levels in the RW group. Immunohistochemical staining also provided similar results.

Conclusion

Rhodiola wallichiana could protect rats from inflammation and oxidative stress injury caused by PM2.5.

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.

STAT6/VDR Axis Mitigates Lung Inflammatory Injury by Promoting Nrf2 Signaling Pathway

Lung inflammatory injury is a global public health concern. It is characterized by infiltration of diverse inflammatory cells and thickening of pulmonary septum along with oxidative stress to airway epithelial cells. STAT6 is a nuclear transcription factor that plays a crucial role in orchestrating the immune response, but its function in tissue inflammatory injury has not been comprehensively studied. Here, we demonstrated that STAT6 activation can protect against particle-induced lung inflammatory injury by resisting oxidative stress. Specifically, genetic ablation of STAT6 was observed to worsen particle-induced lung injury mainly by disrupting the lungs' antioxidant capacity, as reflected by the downregulation of the Nrf2 signaling pathway, an increase in malondialdehyde levels, and a decrease in glutathione levels. Vitamin D receptor (VDR) has been previously proved to positively regulate Nrf2 signals. In this study, silencing VDR expression in human bronchial epithelial BEAS-2B cells consistently suppressed autophagy-mediated activation of the Nrf2 signaling pathway, thereby aggravating particle-induced cell damage. Mechanically, STAT6 activation promoted the nuclear translocation of VDR, which increased the transcription of autophagy-related genes and induced Nrf2 signals, and silencing VDR abolished these effects. Our research provides important insights into the role of STAT6 in oxidative damage and reveals its potential underlying mechanism. This information not only deepens the appreciation of STAT6 but also opens new avenues for the discovery of therapies for inflammatory respiratory system disorders.

Bixin Prevents Colorectal Cancer Development through AMPK-Activated Endoplasmic Reticulum Stress

Chemicals isolated from natural products have been broadly applied in the treatment of colorectal cancer (CRC). Bixin, an apocarotenoid from the seeds of Bixa orellana, exerts multiple pharmacological properties, including neuroprotective, anti-inflammatory, cardioprotective, and antitumor effects; yet, the therapeutic effects of Bixin on CRC are still unknown. Here, we described that Bixin treatment significantly inhibited the proliferation and motility of two CRC cell lines (CaCO2 and SW480) in vitro and in vivo. In addition, Bixin administration has sensitized CRC cells to TNF-related apoptosis-inducing ligand- (TRAIL-) induced cell apoptosis. Moreover, we showed that Bixin treatment initiated the activation of PERK/eIF-2α signal in CaCO2 and SW480 cells, leading to endoplasmic reticulum stress-associated apoptosis. Pharmacological inhibition of AMP-activated protein kinase (AMPK) abrogated the Bixin-induced activation of protein kinase RNA-like endoplasmic reticulum kinase (PERK)/eukaryotic initiation factor 2 alpha (eIF-2α) pathway, as well as reversed the inhibitory effects of Bixin on CRC development. In conclusion, this study indicated that Bixin treatment inhibits the progression of CRC through activating the AMPK/PERK/eIF-2α pathway, providing a novel potential strategy for clinical prevention of CRC.

Astragaloside IV pre-treatment attenuates PM2.5-induced lung injury in rats: Impact on autophagy, apoptosis and inflammation

BACKGROUND

Fine particulate matter (PM2.5) with an aerodynamic diameter of less than 2.5 μm, exerts serious lung toxicity. At present, effective prevention measures and treatment modalities for pulmonary toxicity caused by PM2.5 are lacking. Astragaloside IV (AS-IV) is a natural product that has received increasing attention from researchers for its unique biological functions.

PURPOSE

To investigate the protective effects of AS-IV on PM2.5-induced pulmonary toxicity and identify its potential mechanisms.

METHODS

The rat model of PM2.5-induced lung toxicity was created by intratracheal instillation of PM2.5 dust suspension. The investigation was performed with AS-IV or in combination with autophagic flux inhibitor (Chloroquine) or AMP-sensitive protein kinase (AMPK)-specific inhibitor (Compound C). Apoptosis was detected by terminal deoxy-nucleotidyl transferase dUTP nick end labeling (TUNEL) and western blotting. Autophagy was detected by immunofluorescence staining, autophagic flux measurement, western blotting, and transmission electron microscopy. The AMPK/mTOR pathway was analyzed by western blotting. Inflammation was analyzed by western blotting and suspension array.

RESULTS

AS-IV prevented histopathological injury, inflammation, autophagy dysfunction, apoptosis, and changes in AMPK levels induced by PM2.5. AS-IV increased autophagic flux and inhibited apoptosis and inflammation by activating the AMPK/ mammalian target of rapamycin (mTOR) pathway. However, AS-IV had no protective effect on PM2.5-induced lung injury following treatment with Compound C or Chloroquine.

CONCLUSION

AS-IV prevented PM2.5-induced lung toxicity by restoring the balance among autophagy, apoptosis, and inflammation in rats by activating the AMPK/mTOR signaling pathway.

Protective effect of the effective part of Andrographis paniculata (Burm.f.) Nees on PM2.5-induced lung injury in rats by modulating the NF-κB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Andrographis paniculata (Burm.f.) Nees, a traditional Chinese herb, has been widely used in various Asian countries as a treatment for upper respiratory tract infections for centuries.

AIM OF THE STUDY

Continuous inhalation of fine particulate matter (PM_2.5) may induce various respiratory diseases. This study elucidated the protective effect of the effective part of Andrographis paniculata (Burm.f.) Nees (AEP) against PM_2.5-induced lung injury and detailed the underlying mechanism.

MATERIALS AND METHODS

Male Wistar rats were orally administered 0.5% sodium carboxymethylcellulose (CMC-Na), andrographolide (AG) (200 mg/kg) and AEP (100 mg/kg, 200 mg/kg and 400 mg/kg) once a day for 28 days. The rats were intratracheally instilled with PM_2.5 suspension (8 mg/kg) every other day beginning on the 24th day for a total of 3 times. On the 29th day, bronchoalveolar lavage fluid (BALF) was collected to analyze the levels of lactate dehydrogenase (LDH), acid phosphatase (ACP), alkaline phosphatase (AKP), total proteins (TP), tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6). Hematoxylin & eosin staining was conducted to evaluate the pathological changes in the lung tissues. The protein expression of NF-κB p65 in the lung tissues was analyzed by immunohistochemistry staining. Moreover, the nuclear translocation of NF-κB p65 and the phosphorylation of IκBα were analyzed by western blotting.

RESULTS

PM_2.5 exposure caused lung toxicity, which was characterized by pathological injury and increased levels of LDH, ACP, AKP and TP in BALF. Meanwhile, PM_2.5 exposure induced lung inflammatory response, including infiltration of inflammatory cells and increased levels of inflammatory factors, such as TNF-α and IL-6 in BALF. AEP treatment significantly ameliorated the PM_2.5-induced lung toxicity and the inflammatory response in rats. Moreover, AEP significantly inhibited the PM_2.5-induced upregulation of NF-κB p65 protein expression, phosphorylation of IκBα and nuclear translocation of NF-κB p65 in lung tissue. Compared to AG, AEP exhibited a better ability to alleviate PM_2.5-induced pathological damage and decrease the TP level in the BALF.

CONCLUSION

AEP could be used to improve PM_2.5-induced lung injury by modulating the NF-κB pathway, and multicomponent therapy with traditional Chinese medicine may be more effective than single-drug therapy.

Bixin protects mice against bronchial asthma though modulating PI3K/Akt pathway

Accumulating evidence has implicated the potential of natural compounds in treatment of asthma. Bixin is a natural food coloring isolated from the seeds of Bixa Orellana, which possesses anti-tumor, anti-inflammatory and antioxidative properties. Nevertheless, its therapeutic effect in asthma has not been elucidated. Our present study demonstrated that administration of Bixin suppressed allergic airway inflammation and reversed glucocorticoids resistance, as well as alleviated airway remodeling and airway hyperresponsiveness (AHR) in asthmatic mice. In vitro studies showed that Bixin treatment could inhibit the development of epithelial-mesenchymal transition (EMT) mediated by transforming growth factor beta (TGF-β) signaling. Importantly, Bixin antagonized activation of phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) pathway both in vitro and in vivo. Above all, our findings reveal that Bixin functions as a potent antagonist of PI3K/Akt signaling to protect against allergic asthma, highlighting a novel strategy for asthma treatment based on natural products.

Melatonin protects against PM2.5-induced lung injury by inhibiting ferroptosis of lung epithelial cells in a Nrf2-dependent manner

PM2.5 refers to ambient air particulate matter with aerodynamic diameters ≤ 2.5 µm, which has been a global environmental problem threatening public health in recent years. Melatonin serving as one of the predominant hormones secreted by the pineal gland displays multiple pharmacological properties in various diseases. However, little is known about the possible effects of melatonin in the development of lung injury induced by PM2.5. This study was designed to explore the potential roles of melatonin as well as its possible mechanisms in PM2.5-induced lung injury. In the present study, mice were intratracheally instilled with PM2.5 dissolved in sterile water to induce lung injury with or without intragastric administration of melatonin. The results showed that melatonin treatment significantly alleviated lung pathological injury and edema, apart from inhibiting inflammatory cell infiltration. Meantime, melatonin also decreased the makers of ferroptosis and lipid peroxidation products in lung tissues challenged with PM2.5. Additionally, melatonin promoted the nuclear translocation and expression of Nrf2 and the protein degradation of Keap1. However, the pulmonary protection and anti-ferroptosis effect of melatonin were counteracted in Nrf2-deficiency mice. In vitro experiments further demonstrated that Nrf2 knockdown could offset anti-ferroptosis effect of melatonin in MLE-12 lung epithelial cells. Taken together, our study disclosed that melatonin could relieve PM2.5-induced lung injury via inhibiting ferroptosis of lung epithelial cells by activating Nrf2. Hence, melatonin may be a promising candidate against lung injury associated with air particulate matter.

Natural product derived phytochemicals in managing acute lung injury by multiple mechanisms

Acute lung injury (ALI) and its more severe form, acute respiratory distress syndrome (ARDS) as common life-threatening lung diseases with high mortality rates are mostly associated with acute and severe inflammation in lungs. With increasing in-depth studies of ALI/ARDS, significant breakthroughs have been made, however, there are still no effective pharmacological therapies for treatment of ALI/ARDS. Especially, the novel coronavirus pneumonia (COVID-19) is ravaging the globe, and causes severe respiratory distress syndrome. Therefore, developing new drugs for therapy of ALI/ARDS is in great demand, which might also be helpful for treatment of COVID-19. Natural compounds have always inspired drug development, and numerous natural products have shown potential therapeutic effects on ALI/ARDS. Therefore, this review focuses on the potential therapeutic effects of natural compounds on ALI and the underlying mechanisms. Overall, the review discusses 159 compounds and summarizes more than 400 references to present the protective effects of natural compounds against ALI and the underlying mechanism.

Thioredoxin-albumin fusion protein prevents urban aerosol-induced lung injury via suppressing oxidative stress-related neutrophil extracellular trap formation

The number of deaths from air pollution worldwide is estimated at 8.8 million per year, more than the number of deaths from smoking. Air pollutants, such as PM_2.5, are known to induce respiratory and cardiovascular diseases by inducing oxidative stress. Thioredoxin (Trx) is a 12-kDa endogenous protein that exerts antioxidant activity by promoting dithiol disulfide exchange reactions. We previously synthesized human serum albumin-fused thioredoxin (HSA-Trx), which has a longer half-life in plasma compared with Trx, and demonstrated its efficacy against various diseases including respiratory diseases. Here, we examined the effect of HSA-Trx on urban aerosol-induced lung injury in mice. Urban aerosols induced lung injury and inflammatory responses in ICR mice, but intravenous administration of HSA-Trx markedly inhibited these responses. We next analyzed reactive oxygen species (ROS) production in murine lungs using an in vivo imaging system. The results show that intratracheal administration of urban aerosols induced ROS production that was inhibited by intravenously administered HSA-Trx. Finally, we found that HSA-Trx inhibited the urban aerosol-induced increase in levels of neutrophilic extracellular trap (NET) indicators (i.e., double-stranded DNA, citrullinated histone H3, and neutrophil elastase) in bronchoalveolar lavage fluid (BALF). Together, these findings suggest that HSA-Trx prevents urban aerosol-induced acute lung injury by suppressing ROS production and neutrophilic inflammation. Thus, HSA-Trx may be a potential candidate drug for preventing the onset or exacerbation of lung injury caused by air pollutants.

Bixin attenuates carbon tetrachloride induced oxidative stress, inflammation and fibrosis in kidney by regulating the Nrf2/TLR4/MyD88 and PPAR-γ/TGF-β1/Smad3 pathway

Bixin, an natural carotenoid extracted from the seeds of the Bixa orellana has been shown to possess numerous important pharmacological activities. The present study was aimed to investigate the mechanisms of Bixin on carbon tetrachloride (CCl4)-induced kidney inflammation, fibrosis and oxidative stress in mice. Our results showed that Bixin improved renal damage by decreasing the serum levels of creatinine, urea, uric acid and alleviating kidney fibrosis. Bixin ameliorated CCl4-induced inflammation in kidneys by reducing the levels of TNF-α and IL-1β. Bixin suppressed oxidative stress by decreasing the MDA level and increasing the activation of SOD, CAT and GPx. Furthermore, Bixin increased the levels of PPAR-γ, NQO1, HO-1 and the nuclear translocation of Nrf2 in the kidneys of mice. Bixin supplementation inhibited the activation of TLR4, MyD88, NF-κB, TGF-β and Smad3. Thus, this study demonstrated that Bixin possesses anti-oxidant, anti-inflammatory and anti-fibrosis properties through regulating the Nrf2/TLR4/MyD88 and PPAR-γ/TGF-β1/Smad3 pathways.

Bixin Protects Against Kidney Interstitial Fibrosis Through Promoting STAT6 Degradation

Bixin, a natural carotenoid extracted from the seeds of Bixa orellana, has antioxidant and anti-inflammation effects. However, the pharmacological effects and underlying mechanisms of bixin in kidney interstitial fibrosis remain unknown. Partial epithelial-to-mesenchymal transition (EMT) of tubular cells has been linked to renal interstitial fibrosis. Here, we found that in the unilateral ureteral obstruction model, bixin administration could ameliorate kidney interstitial fibrosis. The expression of signal transducer and activator of transcription 6 (STAT6) was dramatically increased in renal tubular cells. Bixin treatment inhibited STAT6 induction. The activation of STAT6 signaling was essential for transforming growth factor β1, fibrotic markers, and EMT-related protein expression in HK2 cells, which was confirmed by using the Stat6^-/- mice. Ubiquitination, but not the acetylation level of STAT6, was induced by bixin treatment and promoted the suppression of phosphorylation and stability of STAT6. P62-dependent autophagy might be involved in this process. The study demonstrated that bixin can be exploited therapeutically to alleviate renal interstitial fibrosis by targeting STAT6 signaling deactivation.

Bixin Attenuates Experimental Autoimmune Encephalomyelitis by Suppressing TXNIP/NLRP3 Inflammasome Activity and Activating NRF2 Signaling

Multiple sclerosis (MS), an autoimmune and degenerative disease, is characterized by demyelination and chronic neuroinflammation. Bixin is a carotenoid isolated from the seeds of Bixa orellana that exhibits various potent pharmacological activities, including antioxidant, anti-inflammatory, and anti-tumor properties. However, the effects of bixin on MS have not yet been examined. To evaluate the effects and underlying molecular mechanisms of bixin on MS, experimental autoimmune encephalomyelitis (EAE) was established in C57BL/6 mice, which were treated via intragastric administration of bixin solutions. To evaluate the molecular mechanisms of bixin, quantitative reverse-transcription PCR, western blot, immunohistochemistry, flow cytometry, and enzyme-linked immunosorbent assay analyses were performed. We found that bixin significantly improved the symptoms and pathology in EAE mice, reduced the release of inflammatory cytokines TNF-α, IL-6, IL-8, IL-17, and IFN-γ, and increased the expression of the anti-inflammatory cytokine IL-10. And bixin reduced the proportion of Th1 and Th17 cells in the spleen and CNS, and suppressed microglia aggregation, and TXNIP/NLRP3 inflammasome activity by scavenging excessive reactive oxygen species (ROS) in EAE mice. Furthermore, bixin inhibited inflammation and oxidative stress via activating nuclear factor erythroid 2-related factor 2 (NRF2), and its downstream genes in EAE mice, meanwhile, these effects were suppressed upon treatment with an NRF2 inhibitor, ML385. Bixin prevented neuroinflammation and demyelination in EAE mice primarily by scavenging ROS through activation of the NRF2 signaling pathway. Taken together, our results indicate that bixin is a promising therapeutic candidate for treatment of MS.

DNA repair enzyme OGG1 promotes alveolar progenitor cell renewal and relieves PM2.5-induced lung injury and fibrosis

Fine particulate matter (PM2.5) airborne pollution increases the risk of chronic respiratory diseases, such as idiopathic pulmonary fibrosis (IPF), which is characterized by non-specific inflammation of the interstitial lung and extensive deposition of collagen fibers. Type 2 alveolar epithelial cells (AEC2s) are alveolar stem cells in the adult lung that contribute to the lung repair process through complex signaling. Our previous studies demonstrated that OGG1, a kind of DNA repair enzyme, have a critical role in protecting cells from oxidative damage and apoptosis induced by PM2.5, but the contribution of OGG1 in proliferation and self-renewal of AEC2s is not known. Here, we constructed OGG1^-/-mice to test the effect and mechanism of OGG1 on PM2.5-induced pulmonary fibrosis and injury in vivo. We detected proliferation and self-renewal of OGG1 overexpression or OGG1 knockout AEC2s after PM2.5 injury by flow cytometry and clone formation. We observed that knockout of OGG1 aggravated pulmonary fibrosis, oxidative stress, and AEC2 cell death in PM2.5-injured mice. In addition, OGG1 is required for the proliferation and renewal of AEC2s after PM2.5 injury. Overexpression of OGG1 promotes the proliferation and self-renewal of AEC2s by inhibiting PM2.5-mediated oxidative stress and NF-κB signaling hyperactivation in vitro. Furthermore, NF-κB inhibitors promoted proliferation and self-renewal of OGG1-deficient AEC2s cells after PM2.5 injury, and attenuated PM2.5-induced pulmonary fibrosis and injury in mice. These data establish OGG1 as a regulator of NF-κB signal that serves to regulate AEC2 cell proliferation and self-renewal, and suggest a mechanism that inhibition of the NF-κB signaling pathway may represent a potential therapeutic strategy for IPF patients with low-expression of OGG1.

Nrf2 mitigates prolonged PM2.5 exposure-triggered liver inflammation by positively regulating SIKE activity: Protection by Juglanin

Air pollution containing particulate matter (PM) less than 2.5 μm (PM2.5) plays an essential role in regulating hepatic disease. However, its molecular mechanism is not yet clear, lacking effective therapeutic strategies. In this study, we attempted to investigate the effects and mechanisms of PM2.5 exposure on hepatic injury by the in vitro and in vivo experiments. At first, we found that PM2.5 incubation led to a significant reduction of nuclear factor erythroid-derived 2-related factor 2 (Nrf2), along with markedly reduced expression of different anti-oxidants. Notably, suppressor of IKKε (SIKE), known as a negative regulator of the interferon pathway, was decreased in PM2.5-incubated cells, accompanied with increased activation of TANK-binding kinase 1 (TBK1) and nuclear factor-κB (NF-κB). The in vitro studies showed that Nrf2 positively regulated SIKE expression under the conditions with or without PM2.5. After PM2.5 treatment, Nrf2 knockdown further accelerated SIEK decrease and TBK1/NF-κB activation, and opposite results were observed in cells with Nrf2 over-expression. Subsequently, the gene loss- and gain-function analysis demonstrated that SIKE deficiency further aggravated inflammation and TBK1/NF-κB activation caused by PM2.5, which could be abrogated by SIKE over-expression. Importantly, SIKE-alleviated inflammation was mainly dependent on TBK1 activation. The in vivo studies confirmed that SIKE- and Nrf2-knockout mice showed significantly accelerated hepatic injury after long-term PM2.5 exposure through reducing inflammatory response and oxidative stress. Juglanin (Jug), mainly isolated from Polygonum aviculare, exhibits anti-inflammatory and anti-oxidant effects. We found that Jug could increase Nrf2 activation, and then up-regulated SIKE in cells and liver tissues, mitigating PM2.5-induced liver injury. Together, all these data demonstrated that Nrf2 might positively meditate SIKE to inhibit inflammatory and oxidative damage, ameliorating PM2.5-induced liver injury. Jug could be considered as an effective therapeutic strategy against this disease by improving Nrf2/SIKE signaling pathway.

Time- and Dose-Resolved Proteome of PM2.5-Exposure-Induced Lung Injury and Repair in Rats

In recent years, airborne fine particulate matter (PM_2.5) is drawing more public attention due to its various physicochemical features and causing pathological harm, as proven by epidemiological and clinical studies. However, the mechanism of PM_2.5-exposure-induced lung injury has not been fully characterized. Here, we established a PM_2.5-induced rat injury model for both short-term and long-term exposures at different concentrations. We employed the Fast-seq technique to profile 6316 proteins and the catTFRE approach to profile 387 transcription factors (TFs) in the lung tissue. In short-term exposure, we elucidated gradually upregulated proteins enriched in response to oxidative stress, phagosome, and the extracellular matrix (ECM)-receptor interaction pathway. Long-term exposure mainly showed the immune response pathway to be consisting of increased lymphocytes and cytokines. Intriguingly, we found that immune-related proteins were recoverable during short-term exposure. During the process of PM_2.5 exposure, upregulated proteins presented dose-dependence in the lung, including stress response at low dose, minor immune response at middle dose, and severe inflammatory response at high dose. This data set provides a rich resource to facilitate the understanding of PM_2.5-induced lung damage and repair mechanism.

Bixin Confers Prevention against Ureteral Obstruction-Caused Renal Interstitial Fibrosis through Activation of the Nuclear Factor Erythroid-2-Related Factor2 Pathway in Mice

Bixin is a natural carotenoid isolated from the seeds of Bixa orellana, with numerous important pharmacological activities, including antioxidant and antifibrotic effects. The nuclear factor erythroid-2-related factor2 (Nrf2) signaling pathway induced by bixin is involved in the process. Excessive reactive oxygen species generation in tubular cells contributes to kidney interstitial fibrosis. The potential therapeutic strategy for bixin in alleviating kidney fibrosis remains largely unclear. In this study, we used unilateral ureteral obstruction (UUO) to establish a renal fibrotic model. Dramatic oxidative DNA damage occurs in kidneys, especially in tubular cells after UUO. In cultured tubular cells, bixin could induce Nrf2 signaling activation by suppressing Nrf2 ubiquitination and increasing its protein stability. Transforming growth factor beta 1-induced epithelial-to-mesenchymal transition (EMT) and extracellular matrix production were suppressed by bixin, and blockade of Nrf2 activation by small interfering RNA could largely reverse the protective effect of bixin. In vivo studies showed that administration of bixin induces Nrf2 signaling activation in tubular cells and markedly attenuates partial EMT of tubular cells and kidney interstitial fibrosis after subjecting to UUO. Together, this study implies that bixin may protect against kidney interstitial fibrosis through stimulating Nrf2 activation in renal tubular cells.

Pharmaceutic application of vitamin D3 on particle-induced fibrotic effects through induction of Nrf2 signals

Fine particulate matter, a major air pollutant across the world, causes a series of pulmonary diseases. Vitamin D is a typical vitamin with emerging roles in inflammation and fibrosis. Different situations and diseases need different doses and modes of vitamin D administration, which challenges the existing vitamin D supplementary rules. Thus, studies of vitamin D applications and their mechanisms in various diseases are important for its future therapeutic applications. In this study, the therapeutic application of vitamin D₃ in chronic particle-exposure-associated lung fibrosis and tissue remodeling was investigated. In vivo studies showed that vitamin D₃ significantly attenuated fibrosis effects by decreasing α-smooth muscle actin-regulated extracellular matrix deposition and restoring expressions of E-cadherin and N-cadherin. With the importance of activated macrophage in the regulation of local epithelium and fibroblast in the process of tissue fibrosis, two separate in vitro systems of co-culture of macrophages with lung epithelium or fibroblast were built. The results confirmed that vitamin D₃ promoted the proliferation of lung epithelium and depressed the fibrosis effects of fibroblasts as well. In addition, our results indicated that the therapeutic effects of vitamin D₃ were through Nrf2 signals. Our work provides convincing experimental evidence for vitamin D therapeutic application to promote tissue repair and improve particle-associated lung fibrosis.

Thymoquinone ameliorates the PM2.5-induced lung injury in rats

BACKGROUND

This study aims to explore the effect of thymoquinone (TQ) on particulate matter 2.5 (PM2.5)-induced lung injury.

METHODS

The PM2.5 sample was provided by Shenyang Environment Monitor Central Station. Lung injury was established by intratracheal instillation PM2.5 (7.5 mg/kg) followed by TQ treatment (20 and 40 mg/kg) for 14 d in rats. Hematoxylin and eosin (HE) and Evans blue dye (EBD) staining were detected on lung tissues. ELISA, real-time PCR, western blotting and TUNEL assays were also performed.

RESULTS

The data showed that TQ diminished lung injury and EBD accumulation. The number of macrophages, neutrophils, eosinophils, and lymphocytes was ameliorated after TQ treatment. In addition, TQ suppressed the inflammation reaction parameters (interleukin-1β and -6, IL-1β and IL-6; tumor necrosis factor-α, TNF-α) and oxidative stress in PM2.5-induced lung injury. The levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase (HO-1) were increased due to the treatment of TQ. The number of TUNEL-positive cells was prominently reduced in TQ-treated rats compared with that in PM2.5 group. Intratracheal instillation PM2.5 activated autophagy, whilst TQ blocked it in lung.

CONCLUSIONS

Taken together, this study provides the first in vivo evidence that TQ suppresses inflammation, oxidative stress, apoptosis, and autophagy in PM2.5-induced lung injury.

Long-term PM2.5 exposure increases the risk of non-small cell lung cancer (NSCLC) progression by enhancing interleukin-17a (IL-17a)-regulated proliferation and metastasis

PM_2.5 is a class of airborne particles and droplets with sustained high levels in many developing countries. Epidemiological studies have indicated that PM_2.5 is closely associated with the increased morbidity and mortality of lung cancer in the world. Unfortunately, the effects of PM_2.5 on lung cancer are largely unknown. In the present study, we attempted to explore the role of PM_2.5 in the etiology of NSCLC. Here, we found that long-term PM_2.5 exposure led to significant pulmonary injury. Epithelial-mesenchymal transition (EMT) and cancer stem cells (CSC) properties were highly induced by PM_2.5 exposure. EMT was evidenced by the significant up-regulation of MMP2, MMP9, TGF-β1, α-SMA, Fibronectin and Vimentin. Lung cancer progression was associated with the increased expression of Kras, c-Myc, breast cancer resistance protein BCRP (ABCG2), OCT4, SOX2 and Aldh1a1, but the decreased expression of p53 and PTEN. Importantly, mice with IL-17a knockout (IL-17a^-/-) showed significantly alleviated lung injury and CSC properties following PM_2.5 exposure. Also, IL-17a^-/--attenuated tumor growth was recovered in PM_2.5-exposed mice injected with recombinant mouse IL-17a, accompanied with significantly restored lung metastasis. Taken together, these data revealed that PM_2.5 could promote the progression of lung cancer by enhancing the proliferation and metastasis through IL-17a signaling.

Particulate Matter 2.5 Induced Developmental Cardiotoxicity in Chicken Embryo and Hatchling

Particulate matter poses health risk to developing organisms. To investigate particulate matters with a diameter smaller than 2.5 um (PM2.5)-induced developmental cardiotoxicity, fertile chicken eggs were exposed to PM2.5 via air cell injection at doses of 0.05, 0.2, 0.5, 2, and 5 mg/egg kg. Morphological changes in the embryonic day four (ED4) and hatchling hearts were assessed with histological techniques. Heart rates of hatchling chickens were measured with electrocardiography. The protein expression levels of nuclear factor kappa-light-chain-enhancer of activated B cells p65 (NF-kb p65), inducible nitric oxide synthase (iNOS), and matrix metallopeptidase 9 (MMP9) were assessed with immunohistochemistry or western blotting in hatchling hearts. PM2.5 exposure elevated areas of heart in ED4 embryo, increased heart rate, and thickened right ventricular wall thickness in hatchling chickens. Immunohistochemistry revealed enhanced NF-kb p65 expression in hatchling hearts. Western blotting results indicated that both iNOS and MMP9 expression were enhanced by lower doses of PM2.5 exposure (0.2 and 0.5 mg/kg) but not 2 mg/kg. In summary, developmental exposure to PM2.5 induced developmental cardiotoxicity in chicken embryo and hatchling chickens, which is associated with NF-kb p65, iNOS, and MMP9.

The role of natural products in revealing NRF2 function

Covering: up to 2020The transcription factor NRF2 is one of the body's major defense mechanisms, driving transcription of >300 antioxidant response element (ARE)-regulated genes that are involved in many critical cellular processes including redox regulation, proteostasis, xenobiotic detoxification, and primary metabolism. The transcription factor NRF2 and natural products have an intimately entwined history, as the discovery of NRF2 and much of its rich biology were revealed using natural products both intentionally and unintentionally. In addition, in the last decade a more sinister aspect of NRF2 biology has been revealed. NRF2 is normally present at very low cellular levels and only activated when needed, however, it has been recently revealed that chronic, high levels of NRF2 can lead to diseases such as diabetes and cancer, and may play a role in other diseases. Again, this "dark side" of NRF2 was revealed and studied largely using a natural product, the quassinoid, brusatol. In the present review, we provide an overview of NRF2 structure and function to orient the general reader, we will discuss the history of NRF2 and NRF2-activating compounds and the biology these have revealed, and we will delve into the dark side of NRF2 and contemporary issues related to the dark side biology and the role of natural products in dissecting this biology.

Use of Plant Proteins as Microencapsulating Agents of Bioactive Compounds Extracted from Annatto Seeds (Bixa orellana L.)

This study aimed to assess the thermal stability of the bioactive compounds from annatto seed extract, encapsulated by ionic gelation using quinoa proteins, lentil proteins, soy proteins, and sodium caseinate as carrying materials. The 10.0% aqueous dispersions of the different proteins (carriers) were prepared and mixed with the annatto seed extract. The dispersions were then extruded into a calcium chloride solution to induce the extract encapsulation. The capsules were characterized by encapsulation efficiency, particle size, infrared transmission spectroscopy, confocal microscopy, and scanning electron microscopy (SEM). The antioxidant and antimicrobial activities, the polyphenol compounds, and bixin content from the free and encapsulated extract were assessed once stored for 12 d at different temperatures (4 °C, 25 °C, and 65 °C). The results demonstrated the ability of the proteins to encapsulate the annatto extract with encapsulation efficiencies ranging from 58% to 80%, where the protein structure and amino acid content were the relevant factors to obtain high encapsulation efficiencies. The free extracts stored at 65 °C for 12 d experienced a degradation of bixin and polyphenol compounds, respectively. Conversely, the encapsulated extract had degradations from ~34.00% to ~4.05% for polyphenol compounds and ~20.0% for bixin, respectively. These proteins have a potential encapsulation capacity of annatto extract by ionic gelation.

Nrf2 deficiency aggravates PM2.5-induced cardiomyopathy by enhancing oxidative stress, fibrosis and inflammation via RIPK3-regulated mitochondrial disorder

PM_2.5 is a well-known air pollutant threatening public health, and long-term exposure to PM_2.5 increases the risk of cardiovascular diseases. Nrf2 plays a pivotal role in the amelioration of PM_2.5-induced lung injury. However, if Nrf2 is involved in PM_2.5-induced heart injury, and the underlying molecular mechanisms have not been explored. In this study, wild type (Nrf2^+/+) and Nrf2 knockout (Nrf2^-/-) mice were exposed to PM_2.5 for 6 months. After PM_2.5 exposure, Nrf2^-/- mice developed severe physiological changes, lung injury and cardiac dysfunction. In the PM_2.5-exposed hearts, Nrf2 deficiency caused significant collagen accumulation through promoting the expression of fibrosis-associated signals. Additionally, Nrf2^-/- mice exhibited greater oxidative stress in cardiac tissues after PM_2.5 exposure. Furthermore, PM_2.5-induced inflammation in heart samples were accelerated in Nrf2^-/- mice through promoting inhibitor of α/nuclear factor κB (IκBα/NF-κB) signaling pathways. We also found that Nrf2^-/- aggravated autophagy initiation and glucose metabolism disorder in hearts of mice with PM_2.5 challenge. Cardiac receptor-interacting protein kinase 3 (RIPK3) expression triggered by PM_2.5 was further enhanced in mice with the loss of Nrf2. Collectively, these results suggested that strategies for enhancing Nrf2 could be used to treat PM_2.5-induced cardiovascular diseases.

Hydrogen Sulfide Attenuates Particulate Matter-Induced Emphysema and Airway Inflammation Through Nrf2-Dependent Manner

Purpose

To investigate whether hydrogen sulfide provide protective effects on atmosphere particulate matter (PM)-induced emphysema and airway inflammation and its mechanism.

Methods

Wild type C57BL/6 and Nrf2 knockout mice were exposed to PM (200 µg per mouse). Hydrogen sulfide or propargylglycine were administered by intraperitoneal injection respectively 30 min before PM exposure, mice were anesthetized 29th day after administration. Mice emphysema, airway inflammation, and oxidative stress were evaluated, the expression of NLRP3, active caspase-1, and active caspase-3 were detected. Alveolar epithelial A549 cells line were transfected with control small interfering RNA (siRNA) or Nrf2 siRNA and then incubated with or without hydrogen sulfide for 30 min before exposed to fine particulate matter for 24 h, cell viability, terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling (TUNEL) assay, the secretion of interleukin (IL)-1β, ASC speck formation, the expression level of NLRP3, active caspase-1, and active caspase-3 were measured.

Results

PM significantly increased mice emphysema and airway inflammation measured by mean linear intercept, alveolar destroy index and total cell, neutrophil counts, cytokines IL-6, tumor necrosis factor (TNF)-α, CXCL1, IL-1β in bronchoalveolar lavage fluid. PM-induced mice emphysema and airway inflammation was greatly attenuated by hydrogen sulfide, while propargylglycine aggravated that. PM-induced oxidative stress was reduced by hydrogen sulfide as evaluated by 8-OHdG concentrations in lung tissues. The expression of NLRP3, active caspase-1, and active caspase-3 enhanced by PM were also downregulated by hydrogen sulfide in mice lung. The protective effect of hydrogen sulfide on emphysema, airway inflammation, inhibiting oxidative stress, NLRP3 inflammasome formation, and anti-apoptosis was inhibited by Nrf2 knockout in mice. Similarly, hydrogen sulfide attenuated the secretion of IL-1β, NLRP3 expression, caspase-1 activation, ASC speck formation, and apoptosis caused by fine particulate matter exposure in A549 cells but not in Nrf2 silenced cells.

Conclusion

Hydrogen sulfide played a protect role in PM-induced mice emphysema and airway inflammation by inhibiting NLRP3 inflammasome formation and apoptosis via Nrf2-dependent pathway.

N-acetylcysteine attenuates PM2.5-induced apoptosis by ROS-mediated Nrf2 pathway in human embryonic stem cells

While the effects of fine particulate matter (PM_2.5) on embryonic toxicity are widely accepted, its exact mechanisms have not yet been fully elucidated, which partially attribute to lack of ideal research model. Embryonic stem cells (ESCs) have the capacity to differentiate into all cell types of three germ layers. Thus, they are ideal resources for the reproductive toxicity assessment in vitro. In the present study, we investigated the effects of PM_2.5 exposure on the oxidative stress and apoptosis of human ESCs (hESCs) and its possible mechanism. Our results showed that strong cytotoxicity high reactive oxygen species (ROS) level and fragmentation of nuclei were observed in the PM_2.5-treated hESCs. Meanwhile, up-regulation of apoptosis as well as down-regulation of Nrf2 signaling pathway were also observed after PM_2.5 treatment. However, we did not detect significant expression change or phosphorylation of Akt and Erk in PM_2.5-treated hESCs. Interestingly, scavenging of PM_2.5-induced ROS by N-acetylcysteine (NAC) could block cell apoptosis and rescue the activity of Nrf2 signaling pathway. In conclusion, we demonstrate that PM_2.5 is toxic to hESCs by inhibition of ROS-mediated Nrf2 pathway activity. Our findings suggest activation of Nrf2 pathway will help develop new strategies for the prevention and treatment of PM_2.5-associated disease.

Vitamin D protects against particles-caused lung injury through induction of autophagy in an Nrf2-dependent manner

Fine particulate matter is a well-known air pollutant threatening public health. Studies have confirmed long-term exposure to the particles could decrease the pulmonary function, induce asthma exacerbation, and chronic obstructive pulmonary disease, as well as increase the incidence and mortality of lung cancer. A clinical study has explored that the prevalence and risks of vitamin D (VD) deficiency in various chronic disease and toxins induced tissue damage. Our current study aimed to explore the mechanism and further therapeutic potential of VD administration to ameliorate fine particles exposure induced pulmonary damage in vivo and in vitro. To elucidate the effects and mechanisms of VD in particles-induced pulmonary damage, a murine model was established with fine particles intratracheal instillation along with VD intramuscular injection. Our study demonstrated that treatment with VD attenuated particles-induced pulmonary damage and promoted tissue repair by repressing of TGFβ1 signaling pathway and upregulation of MMP9 expression. VD treatment could also regulate the autophagy-related signals along with activation of Nrf2 transcription factor. Furthermore, the results from the in vitro study demonstrated that VD protected against particles-induced cells' damage through the induction of autophagy in an Nrf2-dependent manner. VD treatment caused the degradation of P62 and its bound Keap1, which decreased the Nrf2 ubiquitination and increasing its protein stability. Our work explored a novel potential mechanism in the protection of VD in particles-induced pulmonary injury and tissue repair, and could further bring insights into exploring antifine particles exposure caused inflammation among other natural products and contributes to inflammation disease medical therapies.

Optimization of the Microwave-Assisted Extraction Process of Bioactive Compounds from Annatto Seeds (Bixa orellana L.)

This study deals with the extraction, optimization, and evaluation of the antioxidant and antimicrobial activities of bioactive compounds obtained from the seeds of annatto using microwave-assisted extraction as compared to leaching. Annatto seeds were subjected to a microwave treatment of 2450 MHz and power of 700 watts using a response surface design involving four factors: pH (4–11), solvent concentration (ethanol) (50–96%), solvent-to-seed ratio (2–10), and microwave exposure time (0–5 min). The contents of polyphenol compounds and bixin were taken as response variables. Subsequently, the antioxidant and antimicrobial activities were assessed at the optimal processing conditions predicted by the experimental design. Microwaves, solvent concentration, and the solvent-to-seed ratio showed a statistically significant effect for the extraction of polyphenol compounds and bixin. Thus, microwaves accelerated the extraction of those compounds and the slight increase in temperature caused some degradation of the polyphenol compounds. The microwave-assisted extraction increased the contents of polyphenols and bixin along with their antioxidant activity as compared to leaching extraction. However, this technique does not significantly improve the antimicrobial activity against Bacillus cereus and Staphylococcus aureus.