David Sweeney and Fay Hollins contributed equally to this work.
CE Brightling serves on advisory boards for GlaxoSmithKline, AstraZeneca, MedImmune, Roche, and Aerovance; receives honoraria from Novartis; and receives research support from GlaxoSmithKline, AstraZeneca, and MedImmune. The rest of the authors have declared that they have no competing interests.
DS carried out the intracellular calcium measurement and calcium uncaging assays, participated in the experimental design, data analysis and drafted the manuscript. FH carried out the intracellular calcium measurement and collagen gel assays, participated in the experimental design, data analysis and drafted the manuscript. EG carried out the SERCA2 measurement and data analysis. RM carried out the IP3 accumulation assays and data analysis. RS participated in data analysis. RAJC conceived the study, participated in the design and data analysis, and drafted the manuscript. CEB conceived the study, participated in the design and data analysis, and drafted the manuscript. All authors read and approved the final manuscript.
Asthma is characterized by airway hyper-responsiveness and variable airflow obstruction, in part as a consequence of hyper-contractile airway smooth muscle, which persists in primary cell culture. One potential mechanism for this hyper-contractility is abnormal intracellular Ca2+ handling.
We sought to compare intracellular Ca2+ handling in airway smooth muscle cells from subjects with asthma compared to non-asthmatic controls by measuring: i) bradykinin-stimulated changes in inositol 1,4,5-trisphosphate (IP3) accumulation and intracellular Ca2+ concentration, ii) sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) expression, iii) mechanisms of cytoplasmic Ca2+ clearance assessed following instantaneous flash photolytic release of Ca2+ into the cytoplasm.
We found no differences in airway smooth muscle cell basal intracellular Ca2+ concentrations, bradykinin-stimulated IP3 accumulation or intracellular Ca2+ responses. Quantification of SERCA2 mRNA or protein expression levels revealed no differences in ASM cells obtained from subjects with asthma compared to non-asthmatic controls. We did not identify differences in intracellular calcium kinetics assessed by flash photolysis and calcium uncaging independent of agonist-activation with or without SERCA inhibition. However, we did observe some correlations in subjects with asthma between lung function and the different cellular measurements of intracellular Ca2+ handling, with poorer lung function related to increased rate of recovery following flash photolytic elevation of cytoplasmic Ca2+ concentration.
Taken together, the experimental results reported in this study do not demonstrate major fundamental differences in Ca2+ handling between airway smooth muscle cells from non-asthmatic and asthmatic subjects. Therefore, increased contraction of airway smooth muscle cells derived from asthmatic subjects cannot be fully explained by altered Ca2+ homeostasis.
Global Strategy for Asthma Management and Prevention. Global Initiative for Asthma (GINA) 2014. http://www.ginasthma.org. Updated May 2014. Accessed 8th September 2014.
Johnson PR, Roth M, Tamm M, Hughes M, Ge Q, King G, et al. Airway smooth muscle cell proliferation is increased in asthma. Am J Respi Crit Care Med. 2001;164:474–7. CrossRef
Grynkiewicz G, Poenie M, Tsien RY. A new generation of Ca 2+ indicators with greatly improved fluorescence properties. J Biol Chem. 1985;260:3440–50. PubMed
Billington CK, Hall IP. Novel cAMP signalling paradigms: therapeutic implications for airway disease. Br J Pharmacol. 2011;166:401–10. CrossRef
Patel BS, Prabhala P, Oliver BG, Ammit AJ. Inhibitors of PDE4, but Not PDE3, Increase β2-agonist-induced Expression of Anti-inflammatory MKP-1 in Airway Smooth Muscle Cells. Am J Respir Cell Mol Biol 2014 [Epub ahead of print].
- No evidence for altered intracellular calcium-handling in airway smooth muscle cells from human subjects with asthma
Robert Alfred John Challiss
Christopher Edward Brightling
- BioMed Central
Neu im Fachgebiet Innere Medizin
Meistgelesene Bücher aus der Inneren Medizin
Mail Icon II