Lipid peroxidation index of particulate matter: Novel metric for quantifying intrinsic oxidative potential and predicting toxic responses

Ozonolysis of Terpene Flavor Additives in Vaping Emissions: Elevated Production of Reactive Oxygen Species and Oxidative Stress

The production of e-cigarette aerosols through vaping processes is known to cause the formation of various free radicals and reactive oxygen species (ROS). Despite the well-known oxidative potential and cytotoxicity of fresh vaping emissions, the effects of chemical aging on exhaled vaping aerosols by indoor atmospheric oxidants are yet to be elucidated. Terpenes are commonly found in e-liquids as flavor additives. In the presence of indoor ozone (O3), e-cigarette aerosols that contain terpene flavorings can undergo chemical transformations, further producing ROS and reactive carbonyl species. Here, we simulated the aging process of the e-cigarette emissions in a 2 m3 FEP film chamber with 100 ppbv of O3 exposure for an hour. The aged vaping aerosols, along with fresh aerosols, were collected to detect the presence of ROS. The aged particles exhibited 2- to 11-fold greater oxidative potential, and further analysis showed that these particles formed a greater number of radicals in aqueous conditions. The aging process induced the formation of various alkyl hydroperoxides (ROOH), and through iodometric quantification, we saw that our aged vaping particles contained significantly greater amounts of these hydroperoxides than their fresh counterparts. Bronchial epithelial cells exposed to aged vaping aerosols exhibited an upregulation of the oxidative stress genes, HMOX-1 and GSTP1, indicating the potential for inhalation toxicity. This work highlights the indirect danger of vaping in environments with high ground-level O3, which can chemically transform e-cigarette aerosols into new particles that can induce greater oxidative damage than fresh e-cigarette aerosols. Given that the toxicological characteristics of e-cigarettes are mainly associated with the inhalation of fresh aerosols in current studies, our work may provide a perspective that characterizes vaping exposure under secondhand or thirdhand conditions as a significant health risk.

Activation of ERK/NF-kB Pathways Contributes to the Inflammatory Response in Epithelial Cells and Macrophages Following Manganese Exposure

Different types of metals, including manganese (Mn), are constantly encountered in various environmental matrices due to natural and anthropogenic activities. They induce a sustained inflammatory response in various organs, which is considered to be an important priming event in the pathogenesis of several diseases. Mn-induced neuroinflammation and subsequent neurodegeneration are well recognized. However, emerging data suggest that occupationally and environmentally relevant levels may affect various organs, including the lungs. Therefore, the present study was carried out to investigate the effects of Mn (as Mn2+) exposure on the inflammatory response in human normal bronchial (BEAS-2B) and adenocarcinoma alveolar basal (A549) epithelial cells, as well as in murine macrophages (J774). Mn2+ exposure significantly induced mRNA and protein expression of various pro-inflammatory mediators (cytokines and chemokines) in all cells compared to corresponding vehicle controls. Furthermore, Mn2+ treatment also led to increased phosphorylation of extracellular-signal-regulated kinase (ERK)1/2 and nuclear factor-kappa B (NF-kB) p65 in both epithelial cells and macrophages. As expected, cells treated with inhibitors of ERK1/2 (PD98059) and NF-kB p65 (IMD0354) effectively mitigated the expression of various pro-inflammatory mediators induced by Mn2+, suggesting that ERK/NF-kB pathways have a critical role in the Mn2+-induced inflammatory response. Further, in vivo studies are required to confirm these in vitro findings to support clinical translation.

Forced expression of microRNA-221-3p exerts protective effects against manganese-induced cytotoxicity in human lung epithelial cells

Manganese (Mn)-induced pulmonary toxicity and the underlying molecular mechanisms remain largely enigmatic. Further, in recent years, microRNAs (miRNAs) have emerged as regulators of several pollutants-mediated toxicity. In this context, our study aimed at elucidating whether miRNAs are involved in manganese (II) chloride (MnCl2) (Mn2+)-induced cytotoxicity in lung epithelial cells. Growth inhibition of Mn2+ towards normal human bronchial epithelial (BEAS-2B) and adenocarcinomic human alveolar basal epithelial (A549) cells was analyzed by MTT assay following 24 or 48 h treatment. Reactive oxygen species (ROS) generation, mitochondrial membrane potential (ΔΨm), cell cycle arrest, and apoptosis were evaluated by flow cytometry. RT-qPCR and Western blot were performed to analyze the expression of cyclins, anti-oxidant genes, and miRNAs. We used small RNA sequencing to investigate Mn2+-induced changes in miRNA expression patterns. In both cell lines, Mn2+ treatment inhibited growth in a dose-dependent manner. Further, compared with vehicle-treated cells, Mn2+ (250 μM) treatment induced ROS generation, cell cycle arrest, apoptosis, and decreased ΔΨm as well as altered the expression of cyclins and anti-oxidant genes. Sequencing data revealed that totally 296 miRNAs were differentially expressed in Mn2+-treated cells. Among them, miR-221-3p was one of the topmost down-regulated miRNAs in Mn2+-treated cells. We further confirmed this association in A549 cells. In addition, transient transfection was performed to study gain-of-function experiments. Forced expression of miR-221-3p significantly improved cell viability and reduced Mn2+-induced cell cycle arrest and apoptosis in BEAS-2B cells. In conclusion, miR-221-3p may be the most likely target that accounts for the cytotoxicity of Mn2+-exposed lung epithelial cells.

Neutral saccharides and hemicellulose over two urban sites in Indo-Gangetic Plain and Central Europe during winter

Saccharides are ubiquitous organic compounds that are omnipresent in nature and are considered tracers of aerosol sources. Saccharides and hemicellulose were analyzed in the aerosols of two polluted regions (Allahabad, India and Sosnowiec, Poland). The chemical compositions of the compounds and their abundances were significantly different at the two sites. Levoglucosan was the most dominant saccharide present at both sites. Galactosan, anhydroglucofuranose, mannosan, glucose, arabitol, D-pinitol, sucrose, and trehalose were found in Allahabad samples in high abundance but were significantly lower than levoglucosan. Mannosan, galactosan, arabinose, glycerol, and sucrose were significant compounds in Sosnowiec after dominating levoglucosan. The major sources of saccharides present in the Allahabad aerosols are hardwood and agricultural waste-burning emissions, whereas those at Sosnowiec are attributed to the burning of softwood (mainly gymnosperm trees), pine needles, or sporadically grass during the winter. Further, the chemical characteristics of hemicellulose remnants present in ambient aerosol at the Indian and European sites were analyzed and discussed. At both locations, hemicellulose was found using methanolysis of the filter samples; however, its state of preservation was poor. We believe that the primary sources of hemicellulose remnants are incomplete wood burning, crop straw, grass burning, or plant debris. Relatively poor preservation is associated with partial hemicellulose degradation when exposed to elevated temperatures or due to the oxidation and microbial degradation of plant fragments.

Effects of Particulate Matter Inhalation during Exercise on Oxidative Stress and Mitochondrial Function in Mouse Skeletal Muscle

Particulate matter (PM) has deleterious consequences not only on the respiratory system but also on essential human organs, such as the heart, blood vessels, kidneys, and liver. However, the effects of PM inhalation on skeletal muscles have yet to be sufficiently elucidated. Female C57BL/6 or mt-Keima transgenic mice were randomly assigned to one of the following four groups: control (CON), PM exposure alone (PM), treadmill exercise (EX), or PM exposure and exercise (PME). Mice in the three-treatment group were subjected to treadmill running (20 m/min, 90 min/day for 1 week) and/or exposure to PM (100 μg/m3). The PM was found to exacerbate oxidative stress and inflammation, both at rest and during exercise, as assessed by the levels of proinflammatory cytokines, manganese-superoxide dismutase activity, and the glutathione/oxidized glutathione ratio. Furthermore, we detected significant increases in the levels of in vivo mitophagy, particularly in the PM group. Compared with the EX group, a significant reduction in the level of mitochondrial DNA was recorded in the PME group. Moreover, PM resulted in a reduction in cytochrome c oxidase activity and an increase in hydrogen peroxide generation. However, exposure to PM had no significant effect on mitochondrial respiration. Collectively, our findings in this study indicate that PM has adverse effects concerning both oxidative stress and inflammatory responses in skeletal muscle and mitochondria, both at rest and during exercise.

Investigating the temporal dynamics of sub-micron particles and particle-bound transition metals in indoor air of a metropolitan city

The present study portrays an association between particle-bound transition metals and children's health. The indoor air quality of the urban metropolitan city households was monitored for four PM sizes, namely PM1.0-2.5, PM0.50-1.0, PM0.25-0.50 and PM<0.25, in major seasons observed in the city; summer and winter. Further transition/heavy metals, viz. Cr, Cu, Fe, Mn, Ni, Pb and Zn, were analysed in PM1-2.5 samples. In order to evaluate the effect, health risk assessment was performed using mathematical and computational model for assessing dermal exposure and dose estimation (multiple path particle dosimetry model version3.0). The study principally targeted the children aged 2-15 years for the health risk assessment. According to the results, for the largest particle size i.e. PM1.0-2.5 the highest deposition was in the head region (49.1%) followed by pulmonary (43.6%) and tracheobronchial region (7.2%), whereas, for the smallest particle size i.e. PM<0.25 the highest deposition was obtained in the pulmonary region (73.0%) followed by the head (13.6%) and TB region (13.2%). Also, the most imperilled group of children with highest dose accumulation was found to be children aged 8-9 years for all particle sizes. Moreover, the dermal exposure dose as evaluated was found to be preeminent for Ni, Zn and Pb. Besides, seasonal variation gesticulated towards elevated concentrations in winter relative to the summer season. Altogether, the study will provide a conception to the researchers in the fields mounting season-specific guidelines and mitigation approaches. Conclusively, the study commends future work focussing on defining the effects of other chemical components on particles and associated transition metal composition along with proper extenuation of the same.

MicroRNA-195-5p mediates arsenic-induced cytotoxicity in human lung epithelial cells: Beneficial role of plant-derived tannic acid

Arsenic (As), a highly toxic metalloid, which causes environmental lung diseases and affects millions of people worldwide. Respiratory epithelial cells are essential for maintaining lung homeostasis, aberrant epithelial damage and death due to exposure to a wide range of environmental pollutants, which are considered to be the initial trigger for many pulmonary diseases. Accumulating evidence has shown that microRNAs (miRNAs) appear to be important players in various normal physiological and pathological processes. Therefore, the present study was carried out to examine the cytotoxic effects of a trivalent form of As (As3+) in normal human bronchial (BEAS-2B) and adenocarcinoma alveolar basal (A549) epithelial cells and the role of miR-195-5p. Further, we also explored the protective effects of a natural dietary polyphenol tannic acid (TA). As3+ (1 μM) treatment in BEAS-2B cells for 24 h induced cytotoxicity by decreasing the cell viability, mitochondrial membrane potential (ΔΨm) and inducing reactive oxygen species (ROS) generation, lipid peroxidation (LPO), cell cycle arrest, and apoptosis, which was associated with a significantly higher level of miR-195-5p expression compared with vehicle control. Forced expression of miR-195-5p alone suppressed cell survival, ΔΨm, regulated cell cycle distribution and induced ROS generation in BEAS-2B cells. As expected, miR-195-5p inhibition effectively rescued BEAS-2B cells from As3+-mediated toxicity, confirming the involvement of miR-195-5p in the cytotoxic effects of As3+. Further, TA pre-treatment expressively alleviated As3+-induced toxicity by suppressing ROS production, miR-195-5p expression, and increasing ΔΨm. These in vitro results indicate that miR-195-5p may be useful as a therapeutic target for treating As3+ toxicity.

Development of Moringa oleifera as functional food targeting NRF2 signaling: antioxidant and anti-inflammatory activity in experimental model systems

Pharmacological activation of nuclear factor erythroid 2 related factor 2 (NRF2) provides protection against several environmental diseases by inhibiting oxidative and inflammatory injury. Besides high in protein and minerals, Moringa oleifera leaves contain several bioactive compounds, predominantly isothiocyanate moringin and polyphenols, which are potent inducers of NRF2. Hence, M. oleifera leaves represent a valuable food source that could be developed as a functional food for targeting NRF2 signaling. In the current study, we have developed a palatable M. oleifera leaf preparation (henceforth referred as ME-D) that showed reproducibly a high potential to activate NRF2. Treatment of BEAS-2B cells with ME-D significantly increased NRF2-regulated antioxidant genes (NQO1, HMOX1) and total GSH levels. In the presence of brusatol (a NRF2 inhibitor), ME-D-induced increase in NQO1 expression was significantly diminished. Pre-treatment of cells with ME-D mitigated reactive oxygen species, lipid peroxidation and cytotoxicity induced by pro-oxidants. Furthermore, ME-D pre-treatment markedly inhibited nitric oxide production, secretory IL-6 and TNF-α levels, and transcriptional expression of Nos2, Il-6, and Tnf-α in macrophages exposed to lipopolysaccharide. Biochemical profiling by LC-HRMS revealed glucomoringin, moringin, and several polyphenols in ME-D. Oral administration of ME-D significantly increased NRF2-regulated antioxidant genes in the small intestine, liver, and lungs. Lastly, prophylactic administration of ME-D significantly mitigated lung inflammation in mice exposed to particulate matter for 3-days or 3-months. In conclusion, we have developed a pharmacologically active standardized palatable preparation of M. oleifera leaves as a functional food to activate NRF2 signaling, which can be consumed as a beverage (hot soup) or freeze-dried powder for reducing the risk from environmental respiratory disease.

Brain-Targeted HFn-Cu-REGO Nanoplatform for Site-Specific Delivery and Manipulation of Autophagy and Cuproptosis in Glioblastoma

Durable glioblastoma multiforme (GBM) management requires long-term chemotherapy after surgery to eliminate remaining cancerous tissues. Among chemotherapeutics, temozolomide is considered as the first-line drug for GBM therapy, but the treatment outcome is not satisfactory. Notably, regorafenib, an oral multi-kinase inhibitor, has been reported to exert a markedly superior effect on GBM suppression compared with temozolomide. However, poor site-specific delivery and bioavailability significantly restrict the efficient permeability of regorafenib to brain lesions and compromise its treatment efficacy. Therefore, human H-ferritin (HFn), regorafenib, and Cu²⁺ are rationally designed as a brain-targeted nanoplatform (HFn-Cu-REGO NPs), fulfilling the task of site-specific delivery and manipulating autophagy and cuproptosis against GBM. Herein, HFn affords a preferential accumulation capacity to GBM due to transferrin receptor 1 (TfR1)-mediated active targeting and pH-responsive delivery behavior. Moreover, regorafenib can inhibit autophagosome-lysosome fusion, resulting in lethal autophagy arrest in GBM cells. Furthermore, Cu²⁺ not only facilitates the encapsulation of regorafenib to HFn through coordination interaction but also disturbs copper homeostasis for triggering cuproptosis, resulting in a synergistical effect with regorafenib-mediated lethal autophagy arrest against GBM. Therefore, this work may broaden the clinical application scope of Cu²⁺ and regorafenib in GBM treatment via modulating autophagy and cuproptosis.