Prakash Y S, Thompson Michael A, Pabelick Christina M
Department of Anesthesiology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
Am J Respir Cell Mol Biol. 2009 Nov;41(5):603-11. doi: 10.1165/rcmb.2008-0151OC. Epub 2009 Feb 12.
There is increasing recognition that neurotrophin (NT) signaling occurs in non-neuronal tissues, including airway smooth muscle (ASM). We recently demonstrated that NTs, such as brain-derived neurotrophic factor (BDNF), enhance intracellular Ca2+ (Ca2+) and force regulation in human ASM. Increased NT expression has been observed in airway diseases, such as asthma and allergy. In the present study, we tested the hypothesis that NTs contribute to inflammation-induced enhancement of ASM contractility. Using human ASM cells and real-time fluorescence Ca2+ imaging, we examined the contribution of the high-affinity tropomyosin-related kinase and low-affinity, pan-NT p75NTR receptors to Ca2+ regulation under control conditions and after exposure to the proinflammatory cytokine TNF-alpha (20 ng/ml). Exposure to TNF-alpha enhanced Ca2+ responses to agonist (acetylcholine, histamine). Exposure to 10 nM BDNF for even 30 minutes substantially and synergistically enhanced TNF-alpha effects on Ca2+ responses to agonist. Small interfering RNA suppression of tropomyosin-related kinase substantially blunted the effect of BDNF on Ca2+ responses to agonist (with greater effect on Ca2+ influx via store-operated Ca2+ entry compared with sarcoplasmic reticulum Ca2+ release) in both control and TNF-alpha-exposed cells. However, p75NTR suppression by small interfering RNA had no significant effect on Ca2+ responses in either cell group. These novel data demonstrate that NTs influence ASM contractility, and suggest a potential role for NTs in airway diseases.
人们越来越认识到神经营养因子（NT）信号传导发生在包括气道平滑肌（ASM）在内的非神经元组织中。我们最近证明，诸如脑源性神经营养因子（BDNF）等NTs可增强人ASM中的细胞内Ca2+（Ca2+）和力调节。在哮喘和过敏等气道疾病中已观察到NTs表达增加。在本研究中，我们测试了NTs促成炎症诱导的ASM收缩性增强这一假说。使用人ASM细胞和实时荧光Ca2+成像，我们研究了在对照条件下以及暴露于促炎细胞因子TNF-α（20 ng/ml）后，高亲和力原肌球蛋白相关激酶和低亲和力泛NT p75NTR受体对Ca2+调节的作用。暴露于TNF-α可增强Ca2+对激动剂（乙酰胆碱、组胺）的反应。即使暴露于10 nM BDNF 30分钟也能显著且协同增强TNF-α对Ca2+对激动剂反应的影响。在对照细胞和TNF-α暴露细胞中，小干扰RNA抑制原肌球蛋白相关激酶均显著减弱了BDNF对Ca2+对激动剂反应的影响（与肌浆网Ca2+释放相比，对通过储存性钙内流的Ca2+内流影响更大）。然而，小干扰RNA抑制p75NTR对任一细胞组的Ca2+反应均无显著影响。这些新数据表明NTs影响ASM收缩性，并提示NTs在气道疾病中可能发挥作用。
