No evidence for altered intracellular calcium-handling in airway smooth muscle cells from human subjects with asthma

作者：Sweeney David; Hollins Fay; Gomez Edith; Mistry Rajendra; Saunders Ruth; Challiss Robert Alfred John^*; Brightling Christopher Edward

来源：BMC Pulmonary Medicine, 2015, 15(1): 12.

DOI：10.1186/s12890-015-0009-z

• Asthma
• Airway smooth muscle
• Calcium
• Sarco/endoplasmic reticulum Ca2+ ATPase type 2 (SERCA2)
• Inositol 1,4,5-trisphosphate

Background: 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.
Methods: 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.
Results: 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.
Conclusions: 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.

• 出版日期2015-2-13