Cigarette Smoke Particles-Induced Airway Hyperreactivity in Vivo and in Vitro

Cigarette smoke is a well-known strong risk factor for inducing airway hyperreactivity (AHR), but the underlying molecular mechanisms are not fully understood. In the present study, mouse in-vivo and in-vitro models were used to study effects of dimethyl sulfoxide (DMSO)-extracted cigarette smoke particles (DSP) on the airway, and to explore the underlying molecular mechanisms that are involved in DSP-induced AHR. In mouse in-vivo model, DSP (0.75, 1.5 or 3 µL/mL) was administered intranasally daily for 7 d. At the end of this period, lung functions were measured with flexiVent™. The results showed that the mice exhibited AHR in a dose-dependent manner following methacholine inhalation in vivo. In mouse in-vitro organ culture model, exposure of mouse tracheal segments to DSP (0.1 µL/mL) with or without the following pharmacological inhibitors: specific c-Jun-N-terminal kinase (JNK) inhibitor SP600125 (10 µM) or the anti-inflammatory drug dexamethasone (1 µM). DSP-induced bradykinin receptor-mediated airway contraction with increased mRNA and protein expressions for bradykinin B₁ and B₂ receptors could be significantly reduced by SP600125 or dexamethasone. In conclusion, the present study demonstrates that DSP could induce AHR in vivo and in vitro. In addition to this, the upregulation of bradykinin receptors in airway is most likely one of the underlying molecular mechanisms involved.