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Maurer M, Lumry WR, Li HH, Aygören-Pürsün E, Busse PJ, Jacobs J, Nurse C, Ahmed MA, Watt M, Yu M. Lanadelumab in Patients 2 to Less Than 12 Years Old With Hereditary Angioedema: Results From the Phase 3 SPRING Study. J Allergy Clin Immunol Pract 2024; 12:201-211.e6. [PMID: 37730089 DOI: 10.1016/j.jaip.2023.09.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 08/16/2023] [Accepted: 09/08/2023] [Indexed: 09/22/2023]
Abstract
BACKGROUND Symptoms of hereditary angioedema (HAE) often first occur during childhood, and HAE attacks in children can be severe and substantially affect health-related quality of life (HRQoL). However, there are no approved long-term prophylaxis treatments for children aged less than 6 years. OBJECTIVE The SPRING Study (NCT04070326) evaluated the safety, pharmacokinetics, and efficacy of lanadelumab and HRQoL in patients aged 2 to less than 12 years. METHODS Over 52 weeks of treatment, patients aged 2 to less than 6 years received lanadelumab 150 mg every 4 weeks (Q4W) and patients aged 6 to less than 12 years received 150 mg every 2 weeks (Q2W) but could switch to Q4W if they were attack-free for 26 weeks. RESULTS We enrolled 21 patients (aged 2 to less than 6 years: n = 4; aged 6 to less than 12 years: n = 17), 20 of whom completed the study. There were no reported serious treatment-emergent adverse events or discontinuations resulting from such events. Treatment-emergent adverse events were reported for 17 patients (81.0%). The most common TEAE was injection site pain. Overall systemic exposure was comparable for both age groups. The mean (SD) attack rate during treatment decreased by 94.8% from baseline (1.84 [1.53] to 0.08 [0.17] attacks/mo), and 16 (76.2%) patients were attack-free. The attack rate reduction in both age groups was similar during the first 26-week fixed-dosing treatment. Seven patients switched from Q2W to Q4W and remained attack-free. A large, clinically meaningful increase in the Pediatric Quality of Life Inventory Generic Core Scale Total Score and a large increase in the Pediatric Quality of Life Inventory Generic Core Scale-Family Impact Module Total Score from baseline to end of study (better HRQoL) were observed. CONCLUSIONS Findings support safety, efficacy, and improved HRQoL with lanadelumab 150 mg Q2W and Q4W regimens for the prevention of HAE attacks in patients aged 2 to less than 12 years.
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Affiliation(s)
- Marcus Maurer
- Institute of Allergology, Charité-Universitätsmedizin Berlin, corporate member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Berlin, Germany; Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Immunology and Allergology, Berlin, Germany.
| | | | - H Henry Li
- Institute for Asthma and Allergy, Chevy Chase, Md
| | - Emel Aygören-Pürsün
- Department for Children and Adolescents, Angioedema Centre, University Hospital Frankfurt, Goethe University, Frankfurt, Germany
| | - Paula J Busse
- Division of Allergy and Clinical Immunology, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Joshua Jacobs
- Allergy and Asthma Clinical Research, Walnut Creek, Calif
| | | | - Mariam A Ahmed
- Takeda Development Center Americas, Inc, Lexington, Mass
| | - Maureen Watt
- Takeda Development Center Americas, Inc, Lexington, Mass
| | - Ming Yu
- Takeda Development Center Americas, Inc, Lexington, Mass
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Hide M, Ohsawa I, Nurse C, Yu M. Efficacy and safety of lanadelumab in Japanese patients with hereditary angioedema: A phase 3 multicenter, open-label study. J Dermatol 2023; 50:1381-1391. [PMID: 37574953 DOI: 10.1111/1346-8138.16909] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 06/20/2023] [Accepted: 07/13/2023] [Indexed: 08/15/2023]
Abstract
The safety and efficacy of lanadelumab for the prevention of hereditary angioedema (HAE) attacks have not been studied in Japanese patients. We report outcomes from a phase 3, multicenter, open-label study (NCT04180163) of lanadelumab in Japanese patients with HAE. Japanese patients with HAE aged ≥12 years with ≥1 investigator-confirmed HAE attack during the 4-week run-in baseline period were enrolled into the study and received lanadelumab 300 mg every 2 weeks subcutaneously for 52 weeks. Dosing could be reduced to 300 mg every 4 weeks during the second 26-week treatment period if patients had well-controlled symptoms (e.g., attack-free) for 6 months. The primary efficacy endpoint was no investigator-confirmed HAE attacks (attack-free status) during days 0-182. Other outcomes included the rate of investigator-confirmed HAE attacks per month (28 days) and lanadelumab safety. Twelve patients (mean ± SD age 41.9 ± 12.4 years) were enrolled. During the first 26 weeks (days 0-182), five (41.7%) patients were attack-free. The mean ± SD HAE attack rate per month decreased by 74.0%, from 3.8 ± 2.4 during baseline to 1.2 ± 2.6 during the overall 52-week treatment period. There were no deaths or discontinuations due to treatment-emergent adverse events (TEAEs), no severe or serious TEAEs related to lanadelumab, and no positive anti-drug antibody results. The most frequent TEAEs were injection-site reactions (37 events in six patients). Most of the injection-site reaction adverse events were mild in severity. Results of this study support the findings from two global phase 3 studies for lanadelumab use as prophylactic therapy in Japanese patients with HAE.
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Affiliation(s)
- Michihiro Hide
- Department of Dermatology, Hiroshima City Hiroshima Citizens Hospital, Hiroshima, Japan
- Department of Dermatology, Hiroshima University, Hiroshima, Japan
| | - Isao Ohsawa
- Department of Nephrology, Internal Medicine, Saiyu Soka Hospital, Soka, Japan
- Department of Nephrology, Juntendo University Faculty of Medicine, Bunkyo-ku, Japan
| | - Christina Nurse
- Takeda Development Center Americas, Inc., Lexington, Massachusetts, USA
| | - Ming Yu
- Takeda Development Center Americas, Inc., Lexington, Massachusetts, USA
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Lumry W, Bernstein J, Tachdjian R, Wedner HJ, Yang W, Maurer M, Martinez-Saguer I, Farkas H, Nurse C, Yu M. Efficacy of lanadelumab at fixed and modified dosing regimens in patients aged 2 to <12 years old with hereditary angioedema (HAE) in the phase 3, open-label, multicenter SPRING Study. J Allergy Clin Immunol 2023. [DOI: 10.1016/j.jaci.2022.12.437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Craig T, Tachdjian R, Bernstein J, Anderson J, Nurse C, Watt M, Juethner S, Yu M. LONG-TERM EFFICACY, SAFETY, AND QUALITY OF LIFE WITH LANADELUMAB TREATMENT IN ADOLESCENTS WITH HEREDITARY ANGIOEDEMA. Ann Allergy Asthma Immunol 2022. [DOI: 10.1016/j.anai.2022.08.585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Johnston DT, Busse PJ, Riedl MA, Maurer M, Anderson J, Nurse C, Inhaber N, Yu M, Banerji A. Effectiveness of lanadelumab for preventing hereditary angioedema attacks: Subgroup analyses from the HELP study. Clin Exp Allergy 2021; 51:1391-1395. [PMID: 34166549 PMCID: PMC9290609 DOI: 10.1111/cea.13974] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 06/17/2021] [Accepted: 06/22/2021] [Indexed: 11/29/2022]
Affiliation(s)
| | - Paula J Busse
- Division of Clinical Immunology and Allergy, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Marc A Riedl
- Division of Rheumatology, Allergy and Immunology, University of California San Diego, La Jolla, CA, USA
| | - Marcus Maurer
- Dermatological Allergology, Allergie-Centrum-Charité, Department of Dermatology and Allergy, Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - John Anderson
- Alabama Allergy & Asthma Center, Birmingham, AL, USA
| | | | - Neil Inhaber
- Takeda Pharmaceutical Company Limited, Lexington, MA, USA
| | - Ming Yu
- Takeda Pharmaceutical Company Limited, Lexington, MA, USA
| | - Aleena Banerji
- Division of Rheumatology, Allergy and Immunology, Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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Banerji A, Riedl M, Tachdjian R, Nurse C, Yu M, Kiani S. Long-term efficacy and safety of lanadelumab by baseline attack rates in hereditary angioedema. J Allergy Clin Immunol 2021. [DOI: 10.1016/j.jaci.2020.12.126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Riedl M, Johnston D, Lumry W, Bernstein J, Nurse C, Lu P, Maurer M. Attack-Free Status of Patients With Hereditary Angioedema (HAE) During Extended Treatment With Lanadelumab in the HELP OLE Study. J Allergy Clin Immunol 2020. [DOI: 10.1016/j.jaci.2019.12.626] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Busse P, Tachdjian R, Longhurst H, Lu P, Nurse C, Anderson J. Long-term Efficacy and Safety of Lanadelumab for Prophylactic Treatment in Adolescent Patients with Hereditary Angioedema (HAE). J Allergy Clin Immunol 2020. [DOI: 10.1016/j.jaci.2019.12.623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Busse PJ, Tachdjian R, Martinez-Saguer I, Lu P, Nurse C, Aygoren-Pursun E. Efficacy and safety of lanadelumab for prophylactic treatment in adolescents with hereditary angioedema (HAE). J Allergy Clin Immunol 2019. [DOI: 10.1016/j.jaci.2018.12.131] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Jacobs JS, Bernstein J, Davis-Lorton M, Li HH, Soteres DF, Nurse C, Paes K, Sexton DJ, Longhurst H. Increased Response to Higher Dose Lanadelumab in Hereditary Angioedema Patients: Exploratory Findings From the HELP and HELP OLE Studies. J Allergy Clin Immunol 2019. [DOI: 10.1016/j.jaci.2018.12.116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Schmaier AH, Bauer KA, Cicardi M, Hebert J, Johnston DT, Busse PJ, Paes K, Sexton DJ, Kenniston J, Nurse C, Zaragoza RH. Effect of Lanadelumab on Coagulation Parameters in Patients With Hereditary Angioedema: Findings From The Phase 3 HELP Study. J Allergy Clin Immunol 2019. [DOI: 10.1016/j.jaci.2018.12.123] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Lumry W, Busse P, Lu P, Jain G, Nurse C, Maurer M. SUBCUTANEOUS SELF-ADMINISTRATION OF LANADELUMAB FOR PROPHYLACTIC TREATMENT IN PATIENTS WITH HEREDITARY ANGIOEDEMA (HAE). Ann Allergy Asthma Immunol 2018. [DOI: 10.1016/j.anai.2018.09.186] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Tachdjian R, Anderson J, Busse P, Johnston D, Kiani S, Nurse C, Paes K. LANADELUMAB EFFICACY AFTER SWITCHING FROM PLACEBO: RESULTS FROM THE HELP AND HELP OPEN-LABEL EXTENSION STUDIES. Ann Allergy Asthma Immunol 2018. [DOI: 10.1016/j.anai.2018.09.119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Johnston DT, Anderson JT, Schranz J, Nurse C, Cicardi M. Efficacy of lanadelumab in patients switching from long-term prophylaxis with C1-inhibitor (C1-INH): results from the phase 3 HELP Study. J Allergy Clin Immunol 2018. [DOI: 10.1016/j.jaci.2017.12.152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Riedl MA, Tachdjian R, Schranz J, Nurse C, Bernstein JA. Consistent Lanadelumab Treatment Effect In Patients With Hereditary Angioedema (HAE) Regardless Of Baseline Attack Frequency In The Phase 3 HELP Study. J Allergy Clin Immunol 2018. [DOI: 10.1016/j.jaci.2017.12.153] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
The mammalian carotid body (CB) contains O2-chemoreceptors, i.e. glomus cells, which display increased mitoses and endothelin-1 (ET-1) expression during chronic hypoxia. To investigate whether endogenous ET-1 might mediate these mitogenic effects, we quantified bromodeoxyuridine (BrdU) uptake by tyrosine hydroxylase (TH)-positive glomus cells in rat CB cultures using double-label immunofluorescence. In normoxia (20% O2), 2-day exposure to ET-1 (10-1000 nM) caused a dose-dependent increase in BrdU uptake which peaked (approximately 55% of TH+ cells) at around 500 nM ET-1. In chronic hypoxia (5% O2) alone, BrdU uptake was stimulated (approximately 46% of TH+ cells) relative to normoxia (approximately 30%), but the effect was abolished in the presence of specific (BQ 123) or non-specific (PD 142893) ETA receptor antagonists (10(-5) M). Thus paracrine/autocrine release of ET-1 in the hypoxic carotid body may promote glomus cell mitosis via ET(A) receptors.
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Affiliation(s)
- M Paciga
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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Abstract
Using dissociated carotid body (CB) cultures prepared from neonatal (postnatal days 5-7; P7) or juvenile (postnatal day 19-20; P20) rats, we compared catecholaminergic properties and mechanisms of O2 sensing in glomus cells grown in normoxic (Nox; 20% O2) and chronically hypoxic (CHox; 6% O2) environments for up to 2 weeks. In Nox cultures, basal dopamine (DA) release, determined by HPLC and normalized to the number of tyrosine hydroxylase-positive glomus cells present, was similar for P7 and P20 cultures (approximately 0.3 pmol/1,000 cells/15 min) and was unaffected by culture duration (2 vs. 12 days). Acute hypoxia (5 and 10% O2) caused a dose-dependent stimulation (6x and 3x basal, respectively) in DA release, that was inhibited by nifedipine (10 microM). DA release was also stimulated by high extracellular K+ (30 mM) and iberiotoxin (200 nM), a selective blocker of PO2-regulated, Ca-dependent K+ channel in glomus cells. The stimulatory effect of iberiotoxin was similar to 5% O2 in P20 cultures, but substantially less (about one-half) in P7 cultures. In contrast, in CHox cultures, basal DA release was substantially elevated, approximately 8x Nox levels, although this did not correlate with significant differences in stores. Further, whereas acute hypoxia (5% O2) and high K+ also stimulated DA release in CHox cultures (approximately 2x and approximately 3x basal), iberiotoxin (200 nM) did not. Thus, after chronic hypoxia in vitro, there is an enhanced basal catecholamine release and an apparent down-regulation of functional Ca-dependent K+ channels in CB chemoreceptors. These cellular adaptations may relate to changes in CB chemosensitivity during chronic hypoxemia.
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Affiliation(s)
- A Jackson
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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Abstract
A potential candidate for an oxygen-sensing protein in chemoreceptor cells is a heme-linked multicomponent NADPH oxidase, originally described in neutrophils. The postulated function for the oxidase in chemoreceptor cells is to signal changes in oxygen levels (either in the blood or in the airway lumen) via changes in oxygen metabolite production. An alteration in either superoxide (or dismuted hydrogen peroxide) production may affect the gating properties of the O2-sensitive K+ channels. We have previously reported immunohistochemical localization of gp91 glycoprotein component of the oxidase to the plasma membrane of pulmonary neuroepithelial body (NEB) cells. In this study we have investigated the immunocytochemical localization of the other polypeptide components of the oxidase in NEB cells and in the glomus cells of the carotid body. Cultures of dissociated fetal rabbit NEB cells and newborn rat glomus cells were immunostained with specific antibodies recognizing the various polypeptide subunits of the oxidase using indirect immunofluorescence methods. Immunostaining with the anti-oxidase antibodies reveal strong positive reaction in both NEB and glomus cell clusters while other cells were unstained. The positive reaction product was localized to the plasma membrane and/or cytoplasm and no nuclear staining was observed. Live cell labelling studies with anti-p22 antibody showed positive immunofluorescence on the surface of NEB cells, suggesting that this component of the oxidase is also associated with the plasma membrane. In glomus cells, similar strongly positive immunofluorescence signal was observed for p22 and gp91 in paraformaldehyde-fixed cultures, regardless whether they were permeabilized or not. Taken together, our findings of cell surface localization of gp91 and p22 components of the oxidase in chemoreceptive cells suggests that the heme-linked cytochrome b558 component is associated with the plasma membrane. This association allows for direct interaction with the O2-sensitive K+ channel thus forming the molecular complex of membrane bound O2 sensor.
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Affiliation(s)
- C Youngson
- Department of Pathology, Hospital for Sick Children, Toronto, Ontario, Canada
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Zhong H, Nurse C. Co-cultures of rat petrosal neurons and carotid body type 1 cells. A model for studying chemosensory mechanisms. Adv Exp Med Biol 1996; 410:189-93. [PMID: 9030297 DOI: 10.1007/978-1-4615-5891-0_27] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- H Zhong
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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Abstract
Basic fibroblast growth factor (bFGF) and nerve growth factor (NGF) are known mitogens and/or differentiation factors for cells of the sympathoadrenal lineage. Though carotid body (CB) chemoreceptors (type 1 cells) are considered part of this lineage, their response to bFGF is unknown and so far they appear unresponsive to NGF in vitro. In this study we use whole-cell recording to investigate whether bFGF (and NGF) can influence the development of ionic currents in these chemoreceptors, cultured from fetal (E18-19) rat pups. bFGF (10ng/ml) significantly augmented both transient inward Na+ and outward K+ currents in type 1 cells after only 2 days of treatment; after normalizing for the accompanying increase in cell size, as indicated by whole-cell capacitance, the Na+ current density was nonetheless increased by bFGF. Unlike controls, bFGF-treated type 1 cells readily fired action potentials following depolarization. These effects were not mimicked by NGF (100 ng/ml) treatment. Since the carotid body is one of the most richly vascularized organs and bFGF is a potent angiogenic factor, it is conceivable that variations in local bFGF concentrations during fetal development may contribute to the known species differences in CB chemoreceptor excitability.
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Affiliation(s)
- H Zhong
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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Abstract
In this study we use dissociated cell cultures of the rat carotid body to investigate the adaptive capabilities of endogenous oxygen chemoreceptors, following chronic stimulation by various environmental factors. These oxygen chemoreceptors are catecholamine-containing glomus cells, which derive from the neural crest and resemble adrenal medullary chromaffin cells. Using double-label immunofluorescence, we found that chronic exposure of carotid body cultures to hypoxia (2% to 10% oxygen) caused a significant fraction of tyrosine hydroxylase-positive (TH+) glomus cells to acquire detectable immunoreactivity for growth-associated protein GAP-43. The effect was dose-dependent and peaked around an oxygen tension of 6%, where approximately 30% of glomus cells were GAP-43 positive. Treatment with agents that elevate intracellular cyclic adenosine monophosphate (cAMP) (i.e., dibutyryl cAMP or forskolin) also markedly stimulated GAP-43 expression. Since hypoxia is known to increase cAMP levels in glomus cells, it is possible that the effect of hypoxia on GAP-43 expression was mediated, at least in part, by a cAMP-dependent pathway. Unlike hypoxia, however, cAMP analogs also stimulated neurofilament (NF 68 or NF 160 kD) expression and neurite outgrowth in glomus cells, and these properties were enhanced by retinoic acid. Nerve growth factor, which promotes neuronal differentiation in related crest-derived endocrine cells, and dibutyryl cGMP were ineffective. Thus, it appears that postnatal glomus cells are plastic and can express neuronal traits in vitro. However, since hypoxia stimulated GAP-43 expression, without promoting neurite outgrowth, it appears that the two processes can be uncoupled. We suggest that stimulation of GAP-43 by hypoxia may be important for other physiological processes, e.g., enhancing neurotransmitter release or sensitization of G-protein-coupled receptor transduction.
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Affiliation(s)
- A Jackson
- Department of Biology, McMaster University, Hamilton, Ontario, Canada
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Youngson C, Nurse C, Yeger H, Cutz E. Characterization of membrane currents in pulmonary neuroepithelial bodies: hypoxia-sensitive airway chemoreceptors. Adv Exp Med Biol 1994; 360:179-82. [PMID: 7872081 DOI: 10.1007/978-1-4615-2572-1_23] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- C Youngson
- Department of Pathology, Research Institute, Hospital for Sick Children, Toronto, Ontario
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Abstract
Pulmonary neuroepithelial bodies, composed of innervated clusters of amine- and peptide-containing cells, are widely distributed throughout the airway mucosa of human and animal lungs. Structurally, neuroepithelial bodies resemble chemoreceptors (such as carotid body, taste buds) and are thought to function as hypoxia sensitive airway sensors. Evidence for this is indirect, however, and the mechanism of oxygen sensing by these cells is unknown. Here we culture neuroepithelial bodies isolated from rabbit fetal lungs and identify voltage-activated potassium, calcium and sodium currents using the whole-cell patch clamp technique. Upon exposure to hypoxia there is a reversible reduction (25-30%) in the outward potassium current, with no change in inward currents. In addition, we demonstrate the expression of an oxygen-binding protein (b-cytochrome, NADPH oxidase) on the plasma membrane of these cells. The identification of an oxygen-sensing mechanism (namely the presence of an O2-sensitive potassium channel coupled to an O2 sensor protein) in the cells of pulmonary neuroepithelial bodies indicates that they are transducers of the hypoxia stimulus and hence may function as airway chemoreceptors in the regulation of respiration.
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Affiliation(s)
- C Youngson
- Department of Pathology, Hospital for Sick Children, Toronto, Ontario, Canada
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Abstract
Exposure of humans or animals to chronic hypoxia results in enlargement of the carotid body, a respiratory organ that controls ventilation. The underlying mechanisms are unclear but involve hypertrophy of the chemoreceptor glomus cells. To test whether the latter response can occur independent of the circulation or neural inputs, we exposed cultures of dissociated rat carotid body to chronic hypoxia (2-3 weeks in 6% O2), and compared the 3-D cell volume of immunofluorescent, tyrosine hydroxylase positive (TH+) glomus cells, from data sets obtained by serial confocal microscopy. We found a dramatic increase in volume (3-4 x control) of hypoxia-treated TH + cells, suggesting that glomus cell hypertrophy during chronic hypoxia in vivo is likely due to a local effect of low PO2, rather than the production of ectopic growth factors.
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Affiliation(s)
- L Mills
- Playfair Neuroscience Unit, Toronto Hospital, Toronto Western Division, Ontario, Canada
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