Citations

Moderate hyperoxia (30%–60% O 2 ) in premature infants promotes bronchial airway hyperresponsiveness (AHR) via airway smooth muscle (ASM), a key regulator of bronchoconstriction, bronchodilation, and remodeling. Understanding how O 2 exposure drives long-term bronchial changes in prematurity is critical for developing therapies for airway disease across the lifespan. Premature lungs have immature antioxidant defenses, potentially due to disrupted mitochondrial dynamics, increasing susceptibility to O 2 -induced oxidative stress. Thus, mitochondrial homeostasis is highly relevant to ASM dysfunction and airway disease. We propose that hyperoxia in prematurity promotes mitochondrial dysfunction, and that the gasotransmitter hydrogen sulfide (H 2 S) mitigates O 2 -induced mitochondrial damage in developing ASM. Human fetal ASM (fASM) cells were exposed to moderate hyperoxia to investigate the effects of exogenous H 2 S donors (GYY4137, AP39) and stabilization of cystathionine β-synthase (CBS), an H 2 S biosynthetic enzyme, on mitochondrial structure and function. Hyperoxia impaired fASM cell mitochondrial integrity, while H 2 S donors in particular, or CBS stabilization attenuated adverse O 2 effects on mitochondrial morphology, ROS, respiration, calcium regulation, and contractility. These findings highlight the therapeutic potential of H 2 S in the premature lung exposed to moderate hyperoxia.

Abstract In asthma, pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNFα) drive excessive mitochondrial fission in ASM cells through activating dynamin-related protein 1 (DRP1). Recently, we demonstrated that aryl hydrocarbon receptor (AhR) is expressed in human ASM and is upregulated during inflammation and asthma. This study explores the role of AhR in regulating mitochondrial fission in human ASM cells under pro-inflammatory and asthmatic conditions. Primary human nonasthmatic and asthmatic ASM cells were treated with 6-formylindolo[3,2-b]carbazole (FICZ: AhR agonist), with or without TNFα. Mitochondrial morphology was assessed using MitoTracker staining. DRP1 expression was evaluated in whole-cell and mitochondrial fractions. Loss- and gain-of-function studies (AhR inhibition, knockdown, and overexpression) were performed. AhR binding on the DRP1 promoter and promoter activity were assessed by ChIP-qPCR and luciferase reporter. The effects of AhR activation on oxygen consumption rate (OCR) were analyzed using seahorse XF-Pro. AhR activation significantly inhibited TNFα- and asthma-induced mitochondrial fission in ASM cells via inhibiting DRP1 in both inactive and active forms. In contrast, AhR inhibition or knockdown aggravated mitochondrial fission, while AhR overexpression failed to prevent TNFα-induced fission without ligand activation. Mechanistically, AhR bound the DRP1 promoter and suppressed its promoter activity, consistent with a genomic mode of action, while failing to alter ERK1/2 phosphorylation. Additionally, AhR activation also reduced TNFα- and asthma-induced increase in OCR. Collectively, this study shows that AhR activation prevents mitochondrial fission by inhibiting DRP1 in ASM during inflammation and highlights AhR as a promising therapeutic target for asthma and other airway diseases associated with mitochondrial dysfunction.

Mechanical stretch associated with respiratory support can impair airway development and function in neonates, but the mechanisms are not fully understood. Using developing human airway smooth muscle cells exposed to cyclic forces with static stretch to mimic continuous positive airway pressure, we found that stretch dysregulates long-term cell proliferation and inflammatory cytokine production, and mechanosensitive Piezo ion channels may play a role in the proliferation response.

Tandem exposure to cannabinoids and nicotine during pregnancy poses significant risks to fetal development and health including low birth weight, preterm birth, and perinatal death. However, the effect of co-exposure with the most prominent cannabinoids found in Cannabis sativa (Trans-Δ-9- tetrahydrocannabinol (THC) and cannabidiol (CBD)) alongside nicotine on fetal lung development is not well understood. This study aims to investigate the combinatorial impact of CBD, THC, and nicotine, on human lung development through investigating cellular senescence and the potential role of senolytics in alleviating these effects. Human fetal lung explants from 10 to 16 weeks gestation were cultured on air-liquid interface and treated with various concentrations of nicotine (1µM), CBD, and THC (5µM, or 2.5µM each when used in combination), for 72 hours. To assess the effect of senolytics, the explants were also treated for 48 hours with a combination of CBD, THC, and nicotine. Subsequently, senolytics, Dasatinib (D, 250nM) and Quercetin (Q, 375nM), were added or not for an additional 24 hours. After the 72-hour treatment, explants were collected and either fixed for immunofluorescence staining (IF) analyses or used for RNA extraction and quantitative reverse transcription PCR (qRT-PCR). Additionally, the supernatants were used to evaluate the expression of the senescence-associated secretory phenotype (SASP), conducted by Eve Technologies Corporation-Canada. This study used Luminex xMAP technology for multiplexed quantification of 96 Human cytokines, chemokines, and growth factors. Our results demonstrated that co-exposure to CBD, THC, and nicotine increases the expression of the senescence markers CDKN1A (0.1163±0.02384, p=0.0094, n=8) and CDKN2A (0.005793±0.002157, p=0.0516, n=8) encoding P21 and P16 respectively. Moreover, the IF staining showed increased expression of the DNA damage marker γH2A.X following treatment with CBD+THC+nicotine (7.375±2.154% vs 2.245±0.8329%, p=0.0604, n=6). Furthermore, the lung explants treated with cannabinoids and nicotine released cytokines and chemokines involved in immune responses and inflammation among others IL-6, IL-8, M-CSF, MCP-3, MIP-1β, TNFα, MIP-3β, and TSLP (p<0.05). The addition of D+Q reduced SASP secretion and showed a decreasing trend in expression of the senescence genes CDKN1A and CDKN2A compared to the triple treatment. Taken together, our results showed that the combinatorial exposure to CBD, THC, and nicotine increases senescence, DNA damage, and the senescence-associated secretory phenotypes (SASP) secretion. The use of senolytics (D+Q) may prove to be a promising therapeutic option, alleviating several of the negative effects induced by the different substances. RO1HL171915-01A1 RO!HL155104 RO1HL158532-03 ROIHL160570 This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Background and PurposeThe aryl hydrocarbon receptor (AhR) is a ligand‐activated transcription factor that maintains cellular homeostasis. AhR in airway fibroblasts, epithelial and immune cells inhibit inflammatory responses. Nevertheless, its expression and role in airway smooth muscle (ASM), an airway structural cell indispensable in asthma pathophysiology, are obscure. This study uncovers AhR expression, underlying mechanisms, and activity in ASM during inflammation and asthma.Experimental ApproachCultured primary human nonasthmatic and asthmatic ASM cells were treated with TNFα/IL‐13, with/without pharmacological inhibitors targeting PI3K, p38MAPK, JNK, NFkB, and AP1. AhR expression was analysed using RNA‐sequencing, confocal microscopy, qPCR, and immunoblotting. AP1 specific role was confirmed using c‐JUN (AP1) siRNA and ChIP‐qPCR. AhR activity was determined by Nano luciferase in AhR agonist‐treated cells.Key ResultsWe found ubiquitous expression of AhR in ASM with up‐regulation in asthmatic ASM. TNFα increased AhR expression, whereas IL‐13 did not. Furthermore, p38 and JNK inhibition significantly reduced AhR expression with TNFα exposure, whereas PI3K inhibition had no effect. AP1 inhibition and c‐JUN knockdown significantly down‐regulated AhR expression, whereas NFkB inhibition showed no effect. TNFα promoted c‐JUN binding to AhR promoter and increased AhR mRNA expression. Additionally, AhR agonists significantly increased the xenobiotic response element (XRE) activity, CYP1B1, and AhR nuclear expression. TNFα exposure reduced XRE activity and AhR nuclear expression.Conclusion and ImplicationsOur findings suggest inflammation and asthma transcriptionally up‐regulates AhR through the p38/JNK‐AP1 pathway in ASM, identifying a potential therapeutic target for modulating AhR and its downstream effects in asthma.

Introduction: Throughout the lifetime of an asthmatic, the lung undergoes changes in the composition of its extracellular matrix (ECM) and becomes more fibrotic, a characteristic feature of airway remodeling. Due to this, lung functionality decreases as the lung becomes less elastic and airway resistance increases. The ECM proteins constantly network with their respective mechanosensory receptors and regulatory proteins on the cell membrane. These signaling interactions allow for continuous interactions and feedback between the ECM and airway smooth muscle cells (ASM). ASM cells are one of the major structural cells that regular airway remodeling and are the primary target for treating asthma. In this study, we investigated the specific alterations that occur in the ECM of ASM cells treated with TGF-β1. Methods: Human primary airway smooth muscle (ASM) cells were grown to confluency in DMEM/F-12 with 10% FBS and 1% AbAm in standard conditions. Cells were serum deprived for 48 hours prior to experiments. Cells were treated with TGF-β1 (2 ng/mL) in serum free media. Cells were harvested after 48 hours and 200 µg of protein lysate was prepared. Data-independent acquisition (DIA) mass spectrometry was performed at IDeA National Resource for Quantitative Proteomics. Fold changes for ECM class proteins were collected from DIA results. Pathway analysis was then done using Qiagen ingenuity pathway analysis. Furthermore, expression patterns of select proteins were confirmed via western blotting. Results: The effects of TGF-β1 on specific types of collagens, integrins, laminins, and additional ECM proteins were analyzed. Western blotting confirmed similar changes in expression as measured by DIA. TGF-β1 exposure upregulated LAMA4, LAMB2, and LAMC1 which is likely to increase the prevalence of Laminins 221 and 421. TGF-β1 augmented integrin signaling by upregulating ITGA7, ITGA11, ITGA1, ITGB1 and downregulating ITGA2 and ITGB8. TGF-β1 increased expression of TSP1, TSP2, TSP3, TNS-C, FB, Elastin and Versican while downregulating TNS-X. Several interactions between ECM proteins and their sensors and receptors were highlighted for their enrichment. Conclusion: The DIA analysis shows an upregulation of proteins involved in airway remodeling by TGF-β1 in ASM cells. These findings substantiate our previous results as well as provide insights into a more targeted approach in studying ECM-Cell interactions. NIH R01HL171245 (Venkatachalem), R01HL146705 (Venkatachalem), R01HL142061 (Pabelick, Prakash). and IDeA National Resource for Quantitative Proteomics (R24GM137786). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Rationale: Asthma is a chronic inflammatory disease of conducting airways characterized by airway hyperresponsiveness and remodeling. Airway smooth muscle (ASM) is a major structural cell in the airway that contributes to airway hyperresponsiveness and remodeling. Mitochondrial dynamics is a fission/fusion process crucial for optimal function and signal transduction. Inflammation alters the mitochondrial dynamics in ASM, thereby disrupt mitochondrial function and contributes to asthma pathophysiology. The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that regulates cellular homeostasis. Recently, we found upregulation of AhR in response to inflammation and asthma in ASM. Additionally, AhR activation inhibited inflammation-induced ASM proliferation and remodeling. However, the role of AhR in regulating mitochondrial dynamics in ASM during inflammation and asthma is obscure. Objective: The aim of this work is to unveil the role of AhR in regulating mitochondrial structure and function in human ASM during inflammation and asthma. Methods: Primary non-asthmatic and asthmatic human ASM cells isolated from surgical lung sections were cultured in DMEM-F12 medium supplemented with 10% FBS and 1% AbAm. Cells were serum deprived, treated with AhR agonist 6-Formylindolo[3,2-b]carbazole (FICZ: 10 nM) and antagonist CH223191 (10 μM), with/or without TNFα (20 ng/mL). Mitochondrial bioenergetics was determined by Seahorse XFp analyzer. Mitochondrial morphology was visualized using mitotracker dye. Expressions of fission and fusion mRNA and protein were determined by qPCR and immunoblotting. Additionally, AhR role in fusion and fission was confirmed in shRNA mediated AhR knockdown and AhR overexpressed ASM cells. Results: AhR activation by FICZ alleviated TNFα-induced disrupted mitochondrial bioenergetics in non-asthmatic ASM cells as well as in asthmatic ASM. Furthermore, TNFα-induced increased mitochondrial fission and reduced fusion was restored by AhR activation in both asthmatic and non-asthmatic ASM. AhR inhibition by CH223191 and knockdown promoted mitochondrial fission and blunted fusion in non-asthmatic ASM cells. Interestingly, AhR overexpression and activation by FICZ restored the mitochondrial dynamics altered by inflammation and asthma in ASM cells. Conclusion: Collectively, AhR activation promotes mitochondrial fusion and abolishes fission induced by inflammation and asthma in human ASM, thereby maintains mitochondrial structure and homeostasis. Therefore, AhR is a potential therapeutic target to mitigate altered mitochondrial dynamics in ASM during inflammation and asthma. Supported by NIH grants R01-HL171245 (Venkatachalem and Britt), R01-HL146705 (Venkatachalem), R01-HL155095 (Britt), R01-HL142061 (Pabelick, Prakash) This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Abstract Rationale: Tandem exposure to cannabinoids and nicotine during pregnancy poses significant risks to fetal development and health including low birth weight, preterm birth, and perinatal death. However, the effect of co-exposure with the most prominent cannabinoids found in Cannabis sativa (Trans-Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD)) alongside nicotine on fetal lung development is not well understood. This study aims to investigate the combinatorial impact of CBD, THC, and nicotine, on human lung development through investigating cellular senescence and the potential role of senolytics in alleviating these effects.Methods: Human fetal lung explants from 10 to 16 weeks gestation were cultured on air-liquid interface and treated with various concentrations of nicotine (1µM), CBD, and THC (5µM, or 2.5µM each when used in combination), for 72 hours. To assess the effect of senolytics, the explants were also treated for 48 hours with a combination of CBD, THC, and nicotine. Subsequently, senolytics, Dasatinib (D, 250nM) and Quercetin (Q, 375nM), were added or not for an additional 24 hours. After the 72-hour treatment, explants were collected and either fixed for immunofluorescence staining (IF) analyses or used for RNA extraction and quantitative reverse transcription PCR (qRT-PCR). Additionally, the supernatants were used to evaluate the expression of the senescence-associated secretory phenotype (SASP), conducted by Eve Technologies Corporation-Canada. This study used Luminex xMAP technology for multiplexed quantification of 96 Human cytokines, chemokines, and growth factors.Results: Our results demonstrated that co-exposure to CBD, THC, and nicotine increases the expression of the senescence markers CDKN1A (0.1163±0.02384, p=0.0094, n=8) and CDKN2A (0.005793±0.002157, p=0.0516, n=8) encoding P21 and P16 respectively. Moreover, the IF staining showed increased expression of the DNA damage marker ɣH2A.X following treatment with CBD+THC+nicotine (7.375±2.154% vs 2.245±0.8329%, p=0.0604, n=6). Furthermore, the lung explants treated with cannabinoids and nicotine released cytokines and chemokines involved in immune responses and inflammation among others IL-6, IL-8, M-CSF, MCP-3, MIP-1β, TNFα, MIP-3β, and TSLP (p&lt;0.05). The addition of D+Q reduced SASP secretion and showed a decreasing trend in expression of the senescence genes CDKN1A and CDKN2A compared to the triple treatment.Conclusion: Taken together, our results showed that the combinatorial exposure to CBD, THC, and nicotine increases senescence, DNA damage, and the senescence-associated secretory phenotypes (SASP) secretion. The use of senolytics (D+Q) may prove to be a promising therapeutic option, alleviating several of the negative effects induced by the different substances.

Abstract Rationale: While survival of premature infants has improved with NICU interventions, prematurity remains a risk for developing chronic lung diseases. Oxygen supplementation in the NICU is unfortunately necessary, and clinical practice has shifted towards use of moderate hyperoxia (&lt;60% O2) to minimize detrimental effects of very high O2 concentration (80-90%) such as bronchopulmonary dysplasia. However, even moderate hyperoxia increases the risk of bronchial airway diseases and wheezing/asthma with airway hyperreactivity and remodeling. We previously found that moderate hyperoxia induces cellular senescence in human fetal airway smooth muscle cells (fASM) and fibroblasts. However, the mechanisms by which hyperoxia enhances cellular senescence in fASM are not known. We investigated the role of endoplasmic reticulum (ER) stress and mitochondrial dysfunction, using fASM cells exposed to 21% (normoxia) vs. 50% O2 (hyperoxia). Methods: fASM isolated from lungs of 18-20 week aborted fetuses (Mayo IRB exempt; period of rapid bronchial airway growth) were exposed to normoxia, hyperoxia or etoposide (10 µM; positive control for senescence induction). Cells and lysates were harvested at days 2, 3 or 7 to assess markers of senescence markers, ER stress and mitochondrial morphology, and levels of cytosolic and mitochondrial ROS, using real-time fluorescence imaging, Western blotting, immunofluorescence, and a novel immuno-FISH staining of telomere associated foci (TAF). Mitochondria-specific antioxidant MitoQ [100 nM], ER stress inhibitor Salubrinal [12.5 µM] or mitochondrial fission inhibitor Mdivi-1 [10 µM] were used to assess their effects on senescence markers and interactions between ER stress and mitochondria in inducing senescence. Results: Hyperoxia enhanced cellular senescence via upregulation of p21, PAI-1, and Cav-1; downregulation of LMNB1 and Ki-67, with increased γH2A.X- and TAF-positive cells. Hyperoxia increased cytosolic and mitochondrial ROS, and markers of the three ER stress pathways (ATF6, IRE1α, XBP1s, PDI, GADD34). Hyperoxia altered mitochondrial morphology with increased fission protein Drp1 and fusion proteins Mfn1/2. Inhibition of Drp1 with Mdivi-1 blocked mitochondrial fragmentation, but not senescence. However, hyperoxia-induced p21 was reduced by the PERK pathway inhibitor Salubrinal and MitoQ. Conclusions: Hyperoxia induces senescence in fASM via mitochondrial ROS and ER stress: pathways that offer new opportunities to blunt detrimental effects of oxygen in developing lung via mitochondrial targeted antioxidants and/or ER stress inhibition.

Abstract Rationale: The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor and cellular chemical sensor. AhR maintains cellular homeostatsis in respons to endogenous and exogenous organic molecules. Airway smooth muscle (ASM) cells are major structural cells in airway which is involved in characteristic features of asthma such as increased airway wall thickness, airway remodeling and airway hyperresponsiveness. Previously, we found notable expression of AhR in human ASM and its increased expression during inflammation and asthma. However, the mechanisms of enhanced AhR expression in ASM is unknown. Therefore, we examined the role of pro-inflammatory signaling pathways in enhanced AhR expression. Methods: Primary human non-asthmatic and asthmatic ASM cells isolated from surgical lung resections (Mayo IRB approved) were cultured in DMEM-F12 medium supplemented with 10% fetal bovine serum and 1% antibiotic/antimycotic. At ∼80% confluency, cells were serum deprived and treated with TNFα (20 ng/mL), IL13 (50 ng/mL) with or without PI3K/Akt inhibitor (Wortmannin: 50 nM), p38 inhibitor (SB203580: 600 nM), NFkB inhibitor (SN50 20 μM), and AP1 inhibitor (SR11302 10 μM). Subsequently, expression of AhR was determined using RNA sequencing, confocal microscopy, real-time qPCR, and Western blotting. AhR expression in isolated ASM fron lung tissue section was determined using laser capture microdissection (LCM). Moreover, role of AP1 in inducing AhR expression was confirmed using c-JUN (AP1) siRNA transfection in ASM cells. Additionally, binding of AP1 to the AhR promoter region was demonstrated by chromatin-immunoprecipitation (ChIP-qPCR) technique. Results: AhR expression was significantly high in asthmatic ASM cells and tissue than non-asthmatics. Exposure to pro-inflammatory cytokine TNFα increased AhR mRNA and protein expression, whereas IL-13 failed to do so. Furthermore, inhibition of p38 significantly reduced AhR expression whereas PI3K inhibition had no effect, indicating a role for p38 in AhR increased expression. AP1 inhibition significantly downregulated AhR, while NFkB inhibition showed no effect. Similarly, siRNA mediated silencing of c-JUN (AP1) also downregulated AhR, indicating AP1 role in AhR upregulation. Furthermore, transcription factor binding study suggested AhR promoter region has binding site for AP1 and NFkB. Interestingly, ChIP-qPCR study confirmed binding of AP1 at AhR promote region in response to TNFα. Conclusions: Collectively, the current study show that pro-inflammatory cytokine TNFα increases AhR expression through p38-AP1 pathway. The data shows that pro-inflammatory cytokines can regulate AhR expression in ASM, suggesting AhR in ASM has a role in asthma.