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Zhu S, Gladson CL, White KE, Ding Q, Stewart J Jr, Jin TH, Chapman HA Jr, Olman MA. Urokinase receptor mediates lung fibroblast attachment and migration toward provisional matrix proteins through interaction with multiple integrins. Am J Physiol Lung Cell Mol Physiol 297: L97-L 108, 2009. First published May 1, 2009; doi: 10.1l52/ajplung.90283.2008.-Fibroblasts from patients with pulpionary fibrosis express higher levels of the receptor for urokinase, and the extent of fibrosis in some animal models exhibits a dependence on the urokinase receptor. Recent observations have identified the urokinase receptor as a trans-interacting receptor with consequences on signaling and cell responses that vary depending on its interacting partner, the relative levels of expression, and the state of cellular transformation. We undertook this study to define the urokinash-type plasminogen activator cellular receptor (u-PAR)-integrin interactions and to determine the functional consequences of such interactions on normal human lung fibroblast attachment and migration. u-PAR colocalizes in lammelipodia/filopodia with relevant integrins that mediate fibroblast attachment and spreading on the provisiopal matrix proteins vitronectin, fibronectin, and collagens. Inhibitory antibody studies have revealed that human lung fibroblasts utilize αvβ5 to attach to vitronectin, predominantly α5β1 (and αvβ3) to attach to fibronectin, and α1β1, α2β1, and α3β1 to attach to collagen. Blocking studies with α-integrin subunit decoy peptides and u-PAR netftralizing antibodies indicate that u-PAR modulates the integrin mediated attachment to purified provisional matrix proteins, to antiintegrin antibodies, or to fibroproliferative lesions from fibrotic lungs. Furthermore, these decoy peptides blunt fibroblast spreading and migration. We show that u-PAR can interact with multiple a-integrins but with a preference for α3. Taken together, these data demonstrate that u-PAR may interact with multiple integrins in normal human lung fibroblasts thereby promoting attachment, spreading, and migration. Modulation of fibroblast invasion would be expected to lead to amelioration of fibroproliferative diseases of the lung. [ABSTRACT FROM AUTHOR]

Shows that transforming growth factor-β (TGF-β) decreased the intracellular glutathione (GSH) content in murine embryo fibroblasts, which was followed by an increase in collagen I mRNA content and collagen protein production. Prevention of GSH depletion with N-acetylcysteine, GSH, or GSH ester abrogated TGF-β-stimulated collagen production; Stimulation of superoxide production.

Editorial. Focuses on the inducement of pulmonary fibrosis in immune cell-depleted lungs by transforming growth factor-beta. Fibroblast epithelial cell interactions in fibrosis; Transforming growth factor-beta activity in fibrogenesis; Effect of the transforming growth factor-beta on inflammatory cells.

Suggests that u-PAR-integrin interactions modulate fibroblast attachment and migration toward provisional alveolar matrix proteins. Potential of integrin α-chain peptide-encoding adenovirus for providing a novel antiadhesive therapeutic approach for abrogating the fibroproliferative response after lung injury.

Enhanced expression of both integrin α[sub v]β[sub 3] and platelet-derived growth factor receptor (PDGFr) has been described in glioblastoma tumors. We therefore explored the possibility that integrin α[sub v]β[sub 3] cooperates with PDGFr to promote cell migration in glioblastoma cells, and extended the study to identify the Src family members that are activated on PDGF stimulation. Glioblastoma cells utilize integrins α[sub v]β[sub 3] and α[sub v]β[sub 5] to mediate vitronectin attachment. We found that physiologic PDGF stimulation (83 pM, 10 min) of vitronectin-adherent cells promoted the specific recruitment of integrin α[sub v]B[sub 3]-containing focal adhesions to the cell cortex and α[sub v]β[sub 3]-mediated cell motility. Analysis of PDGFr immunoprecipitates indicated an association of the PDGFr β with integrin α[sub v]β[sub 3], but not integrin α[sub v]β[sub 5]. Cells plated onto collagen or laminin, which engage different integrins, exhibited significantly less migration on PDGF stimulation, indicating a cooperation of α[sub v]β[sub 3] and the PDGFr β in glioblastoma cells that promotes migration. Further analysis of the cells plated onto vitronectin indicated that PDGF stimulation caused an increase in Src kinase activity, which was associated with integrin α[sub v]β[sub 3]. In the vitronectin-adherent cells, Lyn was associated preferentially with α[sub v]β[sub 3] both in the presence and absence of PDGF stimulation. In contrast, Fyn was associated with both α[sub v]β[sub 3] and α[sub v]β[sub 5]. Moreover, PDGF stimulation increased the activity of Lyn, but not Fyn, in vitronectin-adherent cells, and the activity of Fyn, but not Lyn, in laminin-adherent cells. Using cells attached to mAb anti-α[sub v]β[sub 3] or mAb anti-integrin α[sub 6], we confirmed the activation of specific members of the Src kinase family with PDGF stimulation. Down-regulation of Lyn expression by siRNA significantly inhibited the cell migration mediated by integrin α[sub v]β[sub 3] in PDGF-stimulated cells, demonstrating the PDGFr β cooperates with integrin α[sub v]β[sub 3] in promoting the motility of vitronectin-adherent glioblastoma cells through a Lyn kinase-mediated pathway. Notably, the data indicate that engagement of different integrins alters the identity of the Src family members that are activated on stimulation with PDGF. [ABSTRACT FROM AUTHOR]

Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disorder with no effective medical treatments available. The generation of myofibroblasts, which are critical for fibrogenesis, requires both a mechanical signal and activated TGF-β; however, it is not clear how fibroblasts sense and transmit the mechanical signal(s) that promote differentiation into myofibroblasts. As transient receptor potential vanilloid 4 (TRPV4) channels are activated in response to changes in plasma membrane stretch/matrix stiffness, we investigated whether TRPV4 contributes to generation of myofibroblasts and/or experimental lung fibrosis. We determined that TRPV4 activity is upregulated in lung fibroblasts derived from patients with IPF. Moreover, TRPV4-deficient mice were protected from fibrosis. Furthermore, genetic ablation or pharmacological inhibition of TRPV4 function abrogated myofibroblast differentiation, which was restored by TRPV4 reintroduction. TRPV4 channel activity was elevated when cells were plated on matrices of increasing stiffness or on fibrotic lung tissue, and matrix stiffness-dependent myofibroblast differentiation was reduced in response to TRVP4 inhibition. TRPV4 activity modulated TGF-β1-dependent actions in a SMAD-independent manner, enhanced actomyosin remodeling, and increased nuclear translocation of the a-SMA transcription coactivator (MRTF-A). Together, these data indicate that TRPV4 activity mediates pulmonary fibrogenesis and suggest that manipulation of TRPV4 channel activity has potential as a therapeutic approach for fibrotic diseases. [ABSTRACT FROM AUTHOR]

The urokinase-type plasminogen activator receptor (uPAR) is a glycosylphosphatidylinositol-linked membrane protein with no cytosolic domain that localizes to lipid raft microdomains. Our laboratory and others have documented that lung fibroblasts from patients with idiopathic pulmonary fibrosis (IPF) exhibit a hypermotile phenotype. This study was undertaken to elucidate the molecular mechanism whereby uPAR ligation with its cognate ligand, urokinase, induces a motile phenotype in human lung fibroblasts. We found that uPAR ligation with the urokinase receptor binding domain (amino-terminal fragment) leads to enhanced migration of fibroblasts on fibronectin in a protease-independent, lipid raft-dependent manner. Ligation of uPAR with the amino-terminal fragment recruited α5β1 integrin and the acylated form of the Src family kinase, Fyn, to lipid rafts. The biological consequences of this translocation were an increase in fibroblast motility and a switch of the integrin-initiated signal pathway for migration away from the lipid raft-independent focal adhesion kinase pathway and toward a lipid raft-dependent caveolin-Fyn-Shc pathway. Furthermore, an integrin homologous peptide as well as an antibody that competes with β1 for uPAR binding have the ability to block this effect. In addition, its relative insensitivity to cholesterol depletion suggests that the interactions of α5β1 integrin and uPAR drive the translocation of α5β1 integrin-acylated Fyn signaling complexes into lipid rafts upon uPAR ligation through protein-protein interactions. This signal switch is a novel pathway leading to the hypermotile phenotype of IPF patient-derived fibroblasts, seen with uPAR ligation. This uPAR dependent, fibrotic matrix-selective, and profibrotic fibroblast phenotype may be amenable to targeted therapeutics designed to ameliorate IPF. [ABSTRACT FROM AUTHOR]

Transforming growth factor (TGF)-β1 induces fibroblast transdifferentiation to myofibroblasts, a process that requires the involvement of integrin-mediated signaling and focal adhesion kinase (FAK). FAK-related non-kinase (FRNK) is known for its role in inhibiting integrin-mediated cell migration; however, its role in myofibroblast differentiation has not been defined. Here, we report that FRNK abrogates TGF-β1-induced myofibroblast differentiation in vitro and in vivo. TGF-β1 can induce α-smooth muscle actin (α-SMA) expression in the presence or absence of FAK; however, TGF-β1-induced α-SMA expression is reduced (~73%) in FAK-deficient fibroblasts. Although both ERK and p38 MAPK activation is required for maximal TGF-β1-induced α-SMA expression, ERK is the major signaling intermediate in cells that express FAK. In contrast, p38MAPKis the dominant mediator of TGF-β1-induced α-SMA expression in FAK-deficient cells. FRNK overexpression blocks TGF-β1-induced ERK or p38 MAPK activation in the presence, and surprisingly, in the absence of FAK. The loss of FRNK was tested in vivo during experimentally induced pulmonary fibrosis in mice. FRNK knock-out mice have a greater increase in α-SMA-expressing cells in response to a pulmonary fibrotic stimulus in vivo, as compared with congenic wild type mice. This is the first time that FRNK loss has been shown to modify the pathobiology in any animal disease model. Together, the data demonstrate that FRNK negatively regulates myofibroblast differentiation in vitro and in vivo. These data further suggest that modulation FRNK expression may be a novel avenue for therapeutic intervention in tissue fibrosis. [ABSTRACT FROM AUTHOR]

The alveolar fibrinolytic system is altered in acute lung injury (ALI). Levels of the fibrinolytic protease inhibitor, plasminogen activator inhibitor-1 (PAI-1), are too low in broncho-alveolar lavage to address its prognostic significance. This study was performed to assess whether PAI-1 antigen in undiluted pulmonary edema fluid levels can identify patients with ALI and predict their outcome. PAI-1 antigen levels in both plasma and edema fluid were higher in ALI compared with hydrostatic edema, and edema fluid PAI-1 values identified those with ALI with high sensitivity and specificity. Both the high plasma and edema fluid PAI-1 antigen values were associated with a higher mortality rate and fewer days of unassisted ventilation in patients with ALI. Differences in PAI-1 activity were concordant with levels of PAI-1 antigen. Although the fibrin-derived alveolar D-dimer levels were strikingly similar in both groups, ALI patients had a higher relative proportion of D-monomer. In conclusion, PAI-1 levels in edema fluid and plasma identify those with ALI that have a poor prognosis. The data indicate that fibrin turnover in early ALI is a consequence of a rapid fibrinogen influx and fractional fibrinolytic inhibition. [ABSTRACT FROM AUTHOR]

Rationale: Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide. Our previous studies have identified that nocturnal hypoxemia causes skeletal muscle loss (i.e., sarcopenia) in in vitro models of COPD. Objectives: We aimed to extend our preclinical mechanistic findings by analyzing a large sleep registry to determine whether nocturnal hypoxemia is associated with sarcopenia in patients with COPD. Methods: Sleep studies from patients with COPD ( n  = 479) and control subjects without COPD ( n  = 275) were analyzed. Patients with obstructive sleep apnea, as defined by apnea-hypopnea index ⩾ 5, were excluded. Pectoralis muscle cross-sectional area (PMcsa) was quantified using computed tomography scans performed within 1 year of the sleep study. We defined sarcopenia as less than the lowest 20% residuals for PMcsa of control subjects, which was adjusted for age and body mass index (BMI) and stratified by sex. Youden's optimal cut-point criteria were used to predict sarcopenia based on mean oxygen saturation during sleep. Additional measures of nocturnal hypoxemia were analyzed. The pectoralis muscle index (PMI) was defined as PMcsa normalized to BMI. Results: On average, males with COPD had a 16.6% lower PMI than control males (1.41 ± 0.44 vs. 1.69 ± 0.56 cm 2 /BMI; P  < 0.001), whereas females with COPD had a 9.4% lower PMI than control females (0.96 ± 0.27 vs. 1.06 ± 0.33 cm 2 /BMI; P  < 0.001). Males with COPD with nocturnal hypoxemia had a 9.5% decrease in PMI versus COPD with normal O 2 (1.33 ± 0.39 vs. 1.47 ± 0.46 cm 2 /BMI; P  < 0.05) and a 23.6% decrease compared with control subjects (1.33 ± 0.39 vs. 1.74 ± 0.56 cm 2 /BMI; P  < 0.001). Females with COPD with nocturnal hypoxemia had an 11.2% decrease versus COPD with normal O 2 (0.87 ± 0.26 vs. 0.98 ± 0.28 cm 2 /BMI; P  < 0.05) and a 17.9% decrease compared with control subjects (0.87 ± 0.26 vs. 1.06 ± 0.33 cm 2 /BMI; P  < 0.001). These findings were largely replicated using multiple measures of nocturnal hypoxemia. Conclusions: We defined sarcopenia in the pectoralis muscle using residuals that take into account age, BMI, and sex. We found that patients with COPD have a lower PMI than patients without COPD and that nocturnal hypoxemia was associated with an additional decrease in the PMI of patients with COPD. Additional prospective analyses are needed to determine a protective threshold of oxygen saturation to prevent or reverse sarcopenia due to nocturnal hypoxemia in COPD.

Sepsis is a systemic inflammatory response that requires effective macrophage metabolic functions to resolve ongoing inflammation. Previous work showed that the mechanosensitive cation channel, transient receptor potential vanilloid 4 (TRPV4), mediates macrophage phagocytosis and cytokine production in response to lung infection. Here, we show that TRPV4 regulates glycolysis in a stiffness-dependent manner by augmenting macrophage glucose uptake by GLUT1. In addition, TRPV4 is required for LPS-induced phagolysosome maturation in a GLUT1-dependent manner. In a cecal slurry mouse model of sepsis, TRPV4 regulates sepsis-induced glycolysis as measured by BAL fluid (BALF) lactate and sepsis-induced lung injury as measured by BALF total protein and lung compliance. TRPV4 is necessary for bacterial clearance in the peritoneum to limit sepsis-induced lung injury. It is interesting that BALF lactate is increased in patients with sepsis compared with healthy control participants, supporting the relevance of lung cell glycolysis to human sepsis. These data show that macrophage TRPV4 is required for glucose uptake through GLUT1 for effective phagolysosome maturation to limit sepsis-induced lung injury. Our work presents TRPV4 as a potential target to protect the lung from injury in sepsis.

Fibroblast to myofibroblast transdifferentiation mediates numerous fibrotic disorders, such as idiopathic pulmonary fibrosis (IPF). We have previously demonstrated that non-muscle myosin II (NMII) is activated in response to fibrotic lung extracellular matrix, thereby mediating myofibroblast transdifferentiation. NMII-A is known to interact with the calcium-binding protein S100A4, but the mechanism by which S100A4 regulates fibrotic disorders is unclear. In this study, we show that fibroblast S100A4 is a calcium-dependent, mechanoeffector protein that is uniquely sensitive to pathophysiologic-range lung stiffness (8-25 kPa) and thereby mediates myofibroblast transdifferentiation. Re-expression of endogenous fibroblast S100A4 rescues the myofibroblastic phenotype in S100A4 KO fibroblasts. Analysis of NMII-A/actin dynamics reveals that S100A4 mediates the unraveling and redistribution of peripheral actomyosin to a central location, resulting in a contractile myofibroblast. Furthermore, S100A4 loss protects against murine in vivo pulmonary fibrosis, and S100A4 expression is dysregulated in IPF. Our data reveal a novel mechanosensor/effector role for endogenous fibroblast S100A4 in inducing cytoskeletal redistribution in fibrotic disorders such as IPF., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: PVDOMICS (Pulmonary Vascular Disease Phenomics) is a precision medicine initiative to characterize pulmonary vascular disease (PVD) using deep phenotyping. PVDOMICS tests the hypothesis that integration of clinical metrics with omic measures will enhance understanding of PVD and facilitate an updated PVD classification., Objectives: The purpose of this study was to describe clinical characteristics and transplant-free survival in the PVDOMICS cohort., Methods: Subjects with World Symposium Pulmonary Hypertension (WSPH) group 1-5 PH, disease comparators with similar underlying diseases and mild or no PH and healthy control subjects enrolled in a cross-sectional study. PH groups, comparators were compared using standard statistical tests including log-rank tests for comparing time to transplant or death., Results: A total of 1,193 subjects were included. Multiple WSPH groups were identified in 38.9% of PH subjects. Nocturnal desaturation was more frequently observed in groups 1, 3, and 4 PH vs comparators. A total of 50.2% of group 1 PH subjects had ground glass opacities on chest computed tomography. Diffusing capacity for carbon monoxide was significantly lower in groups 1-3 PH than their respective comparators. Right atrial volume index was higher in WSPH groups 1-4 than comparators. A total of 110 participants had a mean pulmonary artery pressure of 21-24 mm Hg. Transplant-free survival was poorest in group 3 PH., Conclusions: PVDOMICS enrolled subjects across the spectrum of PVD, including mild and mixed etiology PH. Novel findings include low diffusing capacity for carbon monoxide and enlarged right atrial volume index as shared features of groups 1-3 and 1-4 PH, respectively; unexpected, frequent presence of ground glass opacities on computed tomography; and sleep alterations in group 1 PH, and poorest survival in group 3 PH. PVDOMICS will facilitate a new understanding of PVD and refine the current PVD classification. (Pulmonary Vascular Disease Phenomics Program PVDOMICS [PVDOMICS]; NCT02980887)., Competing Interests: Funding Support and Author Disclosures The study received grants U01 HL125218 (Principal Investigator: Dr Rosenzweig), U01 HL125205 (Principal Investigator: Dr Frantz), U01 HL125212 (Principal Investigator: Dr Hemnes), U01 HL125208 (Principal Investigator: Dr Rischard), U01 HL125175 (Principal Investigator: Dr Hassoun), U01 HL125215 (Principal Investigator: Dr Leopold), and U01 HL125177 (Principal Investigator: Dr Beck) and was supported by the Pulmonary Hypertension Association. Dr Hemnes has served as a consultant for Bayer, United Therapeutics, Janssen, GossamerBio, and Tenax Therapeutics; holds stock in Tenax Therapeutics; and has received grants from the National Institutes of Health, CMREF, and Imara. Dr Leopold is supported by the National Institutes of Health grant U01 125215 and the American Heart Association 19AIML34980000; receives salary support from the Massachusetts Medical Society; has received research funding (to her institution) from Astellas; has served as a consultant for Abbott Vascular and United Therapeutics; and has served as a site principal investigator for a study sponsored by Aria CV. Dr Abidov is supported by research grants from Astellas Pharma, Boehringer Ingelheim, and Kiniksa outside of the submitted work. Dr Rosenzweig has received consulting fees from Acceleron for a scientific advisory board meeting; and her institution receives grant support from Bayer, United Therapeutics, Janssen, and SonVie. Dr Borlaug has received research grants from National Institutes of Health/NHLBI, AstraZeneca, Medtronic, GlaxoSmithKline, Mesoblast, Novartis, and Tenax Therapeutics; and has received consulting fees from Actelion, Amgen, Aria, Axon Therapies, Boehringer Ingelheim, Edwards Lifesciences, Eli Lilly, Imbria, Janssen, Merck, Novo Nordisk, and VADovations. Dr Dubrock has received consulting fees from Janssen Pharmaceuticals; and has served on advisory boards for Janssen Pharmaceuticals and United Therapeutics. Dr Finet is a consultant to Wolters Kluwer Health, Clinical Drug Information Ad Honorem. Dr Frantz has consulting, steering committee, and advisory board relationships with Altavant Sciences, Bayer, Gossamer Bio, Janssen, Shouti, France Foundation, IQVIA, Tenax, UpToDate, and United Therapeutics. Dr Garcia is CEO and founder of Aqualing Therapeutics. Dr Hassoun has served as scientific advisor for Merck Sharp & Dohme, an activity unrelated to the current work. Dr Highland has grants/contracts with Acceleron Pharmaceuticals, Actelion Pharmaceuticals (Janssen), Bayer Healthcare, Boehringer Ingelheim, Eiger Pharmaceuticals, Eli Lilly, Gossamer Bio, United Therapeutics, and Viela Bio (Horizon); has served as a consultant and/or member of a steering or advisory committee with Acceleron Pharmaceuticals, Actelion Pharmaceuticals (Janssen), Boehringer Ingelheim, Forsee, Genentech, Gossamer Bio, and United Therapeutics; and has served on the Speakers Bureau for Actelion Pharmaceuticals (Janssen), Bayer Healthcare, Boehringer Ingelheim, and United Therapeutics. Dr Hill has received research grants for Acceleron, Aerovate. Altavant, Gossamer. Liquidia, Merck, and United Therapeutics; and has served on advisory boards for Acceleron, Aerovate, Altavant, Gossamer, and Liquidia. Dr Maron has relationships with Deerfield Corporation, Actelion Sciences, and Tenax Therapeutics; and has U.S. Patent #9,605,047, Patent pending PCT/US2019/059890, Patent application 2021/133937. Dr Mathai has served as a consultant for Acceleron, Actelion, Bayer, and United Therapeutics. Dr Mehra is supported by National Institutes of Health grants U01HL125177 and UH3HL140144 and the American Heart Association AHA 18SFRN34170013; has received royalties from Up to Date; has received compensation from the American Board of Internal Medicine; and has received an honorarium from the American Academy of Sleep Medicine. M.M. Park has served on the Speakers Bureau of Lantheus Medical Imaging (Definity contrast). Dr Rischard has consulting relationships with Acceleron and United Therapeutics; is on a Steering Committee for Acceleron; and receives research support from Ismed, United Therapeutics, Bayer, Acceleron, Janssen, and AADI. Dr Thomas has served as a consultant for GE, Abbott, egnite, EchoIQ, and Caption Health; as well as spouse employment for Caption Health. Dr Horn has served on the Data and Safety Monitoring Board of AADi Biosciences and SoniVie; has served on the Clinical Events Committee for V-wave; and has served as a consultant for Biotronik. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose., (Copyright © 2022 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

The importance of innate immune cells to sense and respond to their physical environment is becoming increasingly recognized. Innate immune cells (e.g. macrophages and neutrophils) are able to receive mechanical signals through several mechanisms. In this review, we discuss the role of mechanosensitive ion channels, such as Piezo1 and transient receptor potential vanilloid 4 (TRPV4), and cell adhesion molecules, such as integrins, selectins, and cadherins in biology and human disease. Furthermore, we explain that these mechanical stimuli activate intracellular signaling pathways, such as MAPK (p38, JNK), YAP/TAZ, EDN1, NF-kB, and HIF-1α, to induce protein conformation changes and modulate gene expression to drive cellular function. Understanding the mechanisms by which immune cells interpret mechanosensitive information presents potential targets to treat human disease. Important areas of future study in this area include autoimmune, allergic, infectious, and malignant conditions., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Orsini, Perelas, Southern, Grove, Olman and Scheraga.)

The transient receptor potential vanilloid 1 (TRPV 1 ) channel is expressed in human bronchial epithelium (HBE), where it transduces Ca 2+ in response to airborne irritants. TRPV 1 activation results in bronchoconstriction, cough, and mucus production, and may therefore contribute to the pathophysiology of obstructive airway disease. Since children with asthma face the greatest risk of developing virus-induced airway obstruction, we hypothesized that changes in TRPV 1 expression, localization, and function in the airway epithelium may play a role in bronchiolitis and asthma in childhood. We sought to measure TRPV 1 protein expression, localization, and function in HBE cells from children with versus without asthma, both at baseline and after RSV infection. We determined changes in TRPV 1 protein expression, subcellular localization, and function both at baseline and after RSV infection in primary HBE cells from normal children and children with asthma. Basal TRPV 1 protein expression was higher in HBE from children with versus without asthma and primarily localized to plasma membranes (PMs). During RSV infection, TRPV 1 protein increased more in the PM of asthmatic HBE as compared with nonasthmatic cells. TRPV 1 -mediated increase in intracellular Ca 2+ was greater in RSV-infected asthmatic cells, but this increase was attenuated when extracellular Ca 2+ was removed. Nerve growth factor (NGF) recapitulated the effect of RSV on TRPV 1 activation in HBE cells. Our data suggest that children with asthma have intrinsically hyperreactive airways due in part to higher TRPV 1 -mediated Ca 2+ influx across epithelial membranes, and this abnormality is further exacerbated by NGF overexpression during RSV infection driving additional Ca 2+ from intracellular stores.

Ion channels/pumps are essential regulators of innate immune cell function. Macrophages have been increasingly recognized to have phenotypic plasticity and location-specific functions in the lung. Transient receptor potential vanilloid 4 (TRPV4) function in lung injury has been shown to be stimulus- and cell-type specific. In the current review, we discuss the importance of TRPV4 in macrophages and its role in phagocytosis and cytokine secretion in acute lung injury/acute respiratory distress syndrome (ARDS). Furthermore, TRPV4 controls a MAPK molecular switch from predominately c-Jun N-terminal kinase, JNK activation, to that of p38 activation, that mediates phagocytosis and cytokine secretion in a matrix stiffness-dependent manner. Expanding knowledge regarding the downstream mechanisms by which TRPV4 acts to tailor macrophage function in pulmonary inflammatory diseases will allow for formulation of novel therapeutics., (Copyright © 2020 Scheraga, Southern, Grove and Olman.)