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Cholinergic receptor and cyclic stretch-mediated inflammatory gene expression in intact ASM
Jeannette Kanefsky1, Marc Lenburg, Chi-Ming Hai
1Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Box G-B3, Providence, RI 02912, USA.
American Journal of Respiratory Cell and Molecular Biology
|December 13, 2005
Summary
Cyclic stretch, but not carbachol, significantly increases inflammatory gene expression in airway smooth muscle. This effect is dependent on stretch frequency and amplitude, involving L-type voltage-gated calcium channels.
Area of Science:
- Pulmonary Medicine
- Cell Biology
- Molecular Biology
Background:
- Airway smooth muscle (ASM) plays a critical role in respiratory function.
- Inflammatory gene expression in ASM contributes to airway hyperresponsiveness and diseases like asthma.
- Understanding the regulation of ASM inflammatory responses is crucial for developing targeted therapies.
Purpose of the Study:
- To investigate the effects of cholinergic stimulation and cyclic stretch on inflammatory gene expression in intact bovine tracheal smooth muscle.
- To determine the role of stretch amplitude and frequency in regulating inflammatory gene expression.
- To explore the involvement of L-type voltage-gated calcium channels in stretch-induced inflammatory responses.
Main Methods:
- Bovine tracheal smooth muscle tissues were used to measure mRNA expression.
- Limited microarray analysis and reverse transcription-polymerase chain reaction (RT-PCR) were employed.
- Carbachol (cholinergic agonist) and sinusoidal length oscillations (cyclic stretch) were applied to the muscle tissues.
- Nifedipine (L-type calcium channel blocker) was used to assess channel involvement.
Main Results:
- Carbachol (1 microM) induced moderate increases (1.3- to 3.1-fold) in cyclooxygenase (COX)-1, COX-2, IL-8, and plasminogen activator, urokinase type (PLAU) expression.
- Sinusoidal length oscillation (10% amplitude, 1 Hz) caused significant, large increases (12- to 206-fold) in CCL-2, COX-2, IL-1 beta, and IL-6 expression.
- Inflammatory gene expression was highly sensitive to stretch frequency, with reduced frequency significantly attenuating expression (76-93%).
- Amplitude reduction had no significant effect, while nifedipine inhibited stretch-induced expression (40-78%) but not carbachol-induced expression.
- Two groups of genes showed differential responses to stretch: highly responsive (COX-2, IL-6, IL-8) and moderately responsive (CCL2, PLAU).
Conclusions:
- Cyclic stretch, particularly its frequency, is a potent regulator of inflammatory gene expression in airway smooth muscle.
- The findings suggest that L-type voltage-gated calcium channels are involved in mediating stretch-induced inflammatory gene expression.
- These results highlight the mechanical forces acting on airway smooth muscle as important modulators of airway inflammation.