β-Blockers have differential effects on the murine asthma phenotype

Area of Science:

• Pharmacology
• Immunology
• Respiratory Medicine

Background:

• The beta-2 adrenoceptor and adrenaline are crucial for asthma phenotype development in mouse models.
• Differential effects of beta-blockers on asthma suggest biased signaling.
• Previous studies indicated chronic beta-blocker administration could attenuate asthma phenotype.

Purpose of the Study:

• To investigate the role of adrenaline in beta-blocker effects on asthma.
• To test the hypothesis that biased signaling underlies differential beta-blocker efficacy.
• To examine the impact of specific beta-blockers on a murine asthma model.

Main Methods:

• Utilized mice lacking systemic adrenaline (PNMT(-/-)) and wild-type (WT) mice.
• Employed an ovalbumin sensitization and challenge (Ova S/C) murine asthma model.
• Administered four beta-blockers: alprenolol, carvedilol, propranolol, and nadolol.
• Assessed inflammatory cell infiltration, mucous metaplasia, and airway hyperresponsiveness.
• Performed computer simulations of three-state receptor activation models.

Main Results:

• Ova S/C PNMT(-/-) mice did not develop an asthma phenotype.
• Alprenolol, carvedilol, and propranolol induced an asthma phenotype in Ova S/C PNMT(-/-) mice, while nadolol had no effect.
• In Ova S/C WT mice, alprenolol, propranolol, and carvedilol did not affect the asthma phenotype.
• Nadolol prevented the development of the asthma phenotype in Ova S/C WT mice.
• Computational simulations supported the observed ligand actions within a three-state receptor model.

Conclusions:

• Beta-blockers exhibit varied effects on the murine asthma phenotype.
• These differential effects correlate with distinct downstream beta-2 adrenoceptor signaling pathway modulation.
• The findings highlight the importance of biased agonism/antagonism in beta-blocker action and asthma.