Browsing by Author "Rashmi N. Singh"

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In vivo, in vitro, and in silico approaches in the detailed study of di-butyl phthalate (DBP), a plasticizer-induced lung fibrosis via Nrf-2/Keap-1/HO-1 pathway and its regulation
(Academic Press Inc., 2025) Payal Singh; Sneha Kumari; Harshika Chakravortty; Ajai Kumar Pandey; Debabrata Dash; Rashmi N. Singh
The alveolar epithelium is a crucial barrier against external threats, yet it becomes a key player in initiating pulmonary fibrosis when compromised. Despite its importance, the intricate relationship between, DBP exposure and alveolar epithelial cell injury ensuing pro-fibrotic effects remains poorly understood. Phthalates, ubiquitous in nature, pose a significant risk to lung health upon inhalation, acting as immune triggers that cause airway inflammation and epithelial damage. We aimed to investigate the impact of intranasal administration of Di-butyl Phthalate (DBP) inhalation, and its probable effects on normal and asthmatic lungs. DBP was administered via intranasal route in normal and OVA-induced asthmatic mice. DBP exposure enhanced oxidative stress and inflammatory parameters, leading to exacerbated asthmatic response and oxidative lung damage. Enhanced accumulation of immune cells, bronchial thickening, and collagen deposition was noted in histopathological investigations of DBP-exposed lung sections. Curcumin, a plant-derived molecule, significantly mitigated DBP-exposed asthma exacerbations by suppressing NF-κB expression and enhancing NRF2 levels via the Nrf-2/Keap-1/HO-1 signaling pathway. FACS analysis revealed increased CD11b+ cells (32 %) in asthmatic mice which were reduced in the curcumin pre-treatment group (10.5 %). Enhanced epithelial to mesenchymal transition (EMT) was noted in mice lungs and A549 cells where E-cadherin expression was reduced as compared to Vimentin, and α-SMA. Apart from aggravated airway inflammation, DBP exposure damages healthy lungs also. MMP-9/TIMP-1 ratios and collagen-1 levels were restored which were enhanced after DBP exposure. Moreover, antioxidant enzyme levels such as NQO-1, HO-1, and Catalase were significantly enhanced (p < 0.01) and comparable to dexamethasone, a conventional corticosteroid. Notably, both dexamethasone and curcumin treatments effectively regulated the stimulation and accumulation of Nrf-2 in the nucleus, promoting antioxidant production and offering potential therapeutic benefits in mitigating pulmonary fibrosis. OVA and DBP alone caused DNA damage in the lung cells where increased percentage of damaged DNA movement in the tail, tail length, tail moment, and olive tail moment indicated severe damage in the DBP and OVA combined exposure strategies. Dexamethasone and Curcumin treatments reduced the extent of the DNA damage indicating anti-inflammatory and ant-oxidative potentials. Moreover, in silico studies are supportive of therapeutic potential of Curcumin and Dexamethasone in DBP-induced lung inflammation and fibrosis. © 2024 Elsevier Inc.
Short-term exposure to particulate matter (PM10/2.5) from Varanasi, India led to asthma aggravation and early fibrotic changes in mice model: Insights into its regulation
(Elsevier Ltd, 2025) Diksha Sharma; Payal Singh; Prashant Kumar Chauhan; Vandana Soni; Abhay Kumar Singh; Rashmi N. Singh
Background: Particulate matter (PM10/2.5) is a ubiquitous air pollutant with detrimental health impacts where fine particles (PM2.5) are posing serious threats to respiratory health. With potentially worse outcomes, it is silently damaging the lungs of people already suffering from respiratory diseases like asthma. The continuous exposures to poor air quality in recent years raises urgent questions for both, immediate and long-term health impacts. Both PM10/2.5 levels have surpassed the Indian National safety standards raising serious concerns about the environmental and health consequences. Methodology: This study aimed to investigate impact of PM10/2.5 exposures on mice lungs where pathological changes in OVA-induced asthmatic mice lungs were compared with normal mice lungs. BALB/c mice were sensitized with ovalbumin (OVA, i.p), followed by OVA aerosol (1 %OVA) challenge, and later subjected to PM10/2.5 exposures (0.5 mg/kg, i.n) continuously for five consecutive days. Lung samples were assessed for oxidative stress markers (ROS and lipid peroxidation), inflammatory mediators (nitric oxide, histamine, myeloperoxidase, eosinophil peroxidase, IL-6), fibrotic markers (collagen deposition, MMP-9 activity, α-SMA expression), and histopathological changes. Dose-dependent cytotoxicity, oxidative stress induced DNA damage in human alveolar epithelial cells (A549) after PM10/2.5 exposures were thoroughly investigated. Curcumin derived from turmeric (Curcuma longa) is known anti-oxidant and anti-inflammatory molecule, was studied for its therapeutic efficacy on PM-induced asthma aggravations and fibrotic changes. Key findings: Significant lung damage was noted after short-term PM10/2.5 exposures (5 days) with aggravated inflammatory and fibrotic changes in both, normal and asthmatic mice lungs, where PM2.5 exposure was severe. Significant morphological and histopathological changes like lung tissue remodeling, epithelial thickening, and collagen deposition was observed. Enhanced immune cell recruitment, ROS and MDA levels along with significantly decreased key antioxidant enzymes, Superoxide dismutase (SOD) and Catalase, compared to the control group were noted with reduced GSH level. Upregulated expression of NF-kB, a transcription factor after PM10/2.5 exposure was found in normal mice which was heightened in asthmatic mice. Enhanced MMP-9 activity was also confirmed by immunofluorescent detection of Alpha-smooth muscle actin (α-SMA). Curcumin, a plant-derived molecule, significantly mitigated PM2.5 exposed airway inflammation and fibrotic changes in lungs by suppressing NF-κB expression and enhancing Nrf2 level. In vitro studies validated these findings, where dose-dependent decrease in cell viability and increased in ROS level along with apoptotic changes A549 cells were observed after PM exposure. Enhanced IL-6 and PARP-1 expression confirmed progressive PM2.5 exposure induced cytotoxicity in A549 cells which was reduced after curcumin treatment. Significance: These findings draw the attention towards detrimental impacts of poor air quality of Varanasi city with genotoxic effects which have not been reported before. Therapeutic potential of Curcumin as a natural protective agent against PM-induced respiratory damage revealed antioxidant-based interventions. It may be alarming for residents living in such polluted environments, particularly susceptible asthmatic population where silent pathological changes are in progress, thus, more detailed investigations are required along with improved air quality management policies in polluted urban areas in near future. © 2025 Elsevier Ltd