Myofibroblasts are increased in the lung parenchyma in asthma

BackgroundIncreased airway smooth muscle is observed in large and small airways in asthma. Semi-quantitative estimates suggest that cells containing alpha smooth muscle actin (α-SMA) are also increased in the lung parenchyma. This study quantified and characterized α-SMA positive cells (α-SMA+) in the lung parenchyma of non-asthmatic and asthmatic individuals.MethodsPost-mortem sections of peripheral lung from cases of fatal asthma (FA), persons with asthma dying of non-respiratory causes (NFA) and non-asthma control subjects (NAC) were stained for α-SMA, quantified using point-counting and normalised to alveolar basement membrane length and interstitial area.Resultsα-SMA+ fractional area was increased in alveolar parenchyma in both FA (14.7 ± 2.8% of tissue area) and NFA (13.0 ± 1.2%), compared with NAC (7.4 ± 2.4%), p ConclusionsWe conclude that in asthma there is a marked increase in α-SMA+ myofibroblasts in the lung parenchyma. The physiologic consequences of this increase are unknown.研究背景：哮喘患者的大、小气道中可见气道平滑肌增生。半定量评估结果显示，肺实质内表达α平滑肌肌动蛋白（alpha smooth muscle actin, α-SMA）的细胞数量亦存在增加趋势。本研究针对非哮喘及哮喘个体肺实质内α-SMA阳性细胞（α-SMA+）开展定量分析与特征鉴定。 研究方法：采集致死性哮喘（fatal asthma, FA）病例、因非呼吸系统病因死亡的哮喘患者（non-asthma dying of non-respiratory causes, NFA）以及非哮喘对照受试者（non-asthma control subjects, NAC）的外周肺尸检组织切片，对其进行α-SMA染色；采用点计数法完成定量分析，并以肺泡基底膜长度及间质面积作为标准化基准进行归一化处理。 研究结果：相较于非哮喘对照受试者（7.4 ± 2.4%的组织面积占比），致死性哮喘组（14.7 ± 2.8%的组织面积占比）与非呼吸病因死亡哮喘组（13.0 ± 1.2%的组织面积占比）的肺泡肺实质内α-SMA阳性细胞分数面积均显著升高，p 研究结论：本研究证实，哮喘患者肺实质内α-SMA阳性肌成纤维细胞数量存在显著增加，此种细胞增生所带来的生理效应目前仍未明确。