Cooperative Research Centre for Asthma and Airways, The University of Sydney, Sydney, New South Wales, Australia.
Respirology. 2010 Feb;15(2):303-12. doi: 10.1111/j.1440-1843.2009.01683.x. Epub 2010 Jan 11.
PPARgamma levels in asthma- and non-asthma-derived airway smooth muscle cells and PPARgamma activation-induced cell proliferation were investigated. In the presence of FBS, PPARgamma levels were higher in subconfluent asthma-derived cells but lower in confluent cells compared with non-asthma-derived. However, PPARgamma activation did not alter cell proliferation.
Airway remodelling involves thickening of the airway smooth muscle (ASM) bulk. Proliferation of asthma-derived ASM cells is increased in vitro, but underlying mechanisms remain unknown. Peroxisome proliferators activated receptor-gamma (PPARgamma) regulates the cell cycle. It is suggested that PPARgamma agonists have anti-inflammatory effects, which may be valuable in the treatment of asthma, but information regarding their antiproliferative properties in ASM is lacking. Although corticosteroids reduce airway inflammation, in vitro they inhibit proliferation in only non-asthma ASM cells by reducing cyclin D1. We therefore investigated the effects of mitogenic stimulation (foetal bovine serum (FBS)), and a PPARgamma ligand (ciglitazone), on PPARgamma and cyclin D1 expression and proliferation of ASM cells. In addition, we examined the effects of ciglitazone on ASM cell proliferation.
We assessed PPARgamma and cyclin D1 mRNA and protein levels using quantitative PCR and immunoblotting. Cell proliferation was assessed using bromodeoxyuridine uptake.
In the presence of 5% FBS, PPARgamma and cyclin D1 expression decreased over time in non-asthmatic cells but increased in asthmatic cells (compared with sub-confluent cells). FBS-induced proliferation of asthmatic cells increased at all time points, but occurred only at day 7 with non-asthmatic cells (compared with unstimulated time-matched control). Ciglitazone increased PPARgamma expression in both groups, but did not alter cell proliferation, while fluticasone increased PPARgamma protein only in asthmatic cells.
Although in the presence of a mitogenic stimulus, PPARgamma was differentially expressed in asthma- and non-asthma-derived ASM; its expression was not related to the increased proliferation observed in asthmatic ASM.
研究了哮喘和非哮喘气道平滑肌细胞中过氧化物酶体增殖物激活受体γ（PPARγ）水平以及 PPARγ 激活诱导的细胞增殖。在 FBS 存在的情况下，亚汇合哮喘衍生细胞中的 PPARγ 水平高于非哮喘衍生细胞，但在汇合细胞中则较低。然而，PPARγ 激活并未改变细胞增殖。
气道重塑涉及气道平滑肌（ASM）的增厚。体外培养的哮喘衍生 ASM 细胞增殖增加，但潜在机制尚不清楚。过氧化物酶体增殖物激活受体-γ（PPARγ）调节细胞周期。有人认为，PPARγ 激动剂具有抗炎作用，这在哮喘治疗中可能很有价值，但关于它们在 ASM 中的抗增殖特性的信息却很少。尽管皮质类固醇可减轻气道炎症，但在体外，它们仅通过减少细胞周期蛋白 D1 来抑制非哮喘 ASM 细胞的增殖。因此，我们研究了有丝分裂刺激（胎牛血清（FBS））和 PPARγ 配体（吡格列酮）对 ASM 细胞中 PPARγ 和细胞周期蛋白 D1 表达和增殖的影响。此外，我们还研究了吡格列酮对 ASM 细胞增殖的影响。
我们使用定量 PCR 和免疫印迹法评估了 PPARγ 和细胞周期蛋白 D1 mRNA 和蛋白质水平。使用溴脱氧尿苷摄取评估细胞增殖。
在 5％FBS 存在的情况下，非哮喘细胞中 PPARγ 和细胞周期蛋白 D1 的表达随时间推移而降低，但在哮喘细胞中则增加（与亚汇合细胞相比）。FBS 诱导的哮喘细胞增殖在所有时间点均增加，但仅在非哮喘细胞中于第 7 天发生（与未刺激的时间匹配对照相比）。吡格列酮增加了两组中的 PPARγ 表达，但并未改变细胞增殖，而氟替卡松仅增加了哮喘细胞中的 PPARγ 蛋白。
尽管在有丝分裂刺激物存在的情况下，哮喘和非哮喘衍生的 ASM 中 PPARγ 的表达存在差异；但其表达与观察到的哮喘 ASM 中增殖增加无关。
