Research Unit of Internal Medicine, University of Oulu, Oulu, Finland.
Center of Internal Medicine and Respiratory Medicine and Medical Research Center Oulu, Oulu University Hospital, Oulu, Finland.
Respir Res. 2022 Aug 13;23(1):206. doi: 10.1186/s12931-022-02129-z.
Variants of NHL repeat-containing protein 2 (NHLRC2) have been associated with severe fibrotic interstitial lung disease in early childhood and NHLRC2 has been listed as a differentially expressed gene between rapidly and slowly progressing idiopathic pulmonary fibrosis (IPF) patients. However, its cell type-specific localization in human lung tissue is unknown. The aim of this study was to evaluate NHLRC2 mRNA and protein expression in different cell types of lung tissue samples and to investigate the effect of transforming growth factor (TGF)-β1 exposure on NHLRC2 expression in vitro.
The NHLRC2 expression in lung tissue samples was studied by immunohistochemistry (50 IPF, 10 controls) and mRNA in situ hybridization (8 IPF, 3 controls). The immunohistochemical NHLRC2 expression was quantified with image analysis software and associated with the clinical and smoking data of the patients. NHLRC2 expression levels in primary stromal and small airway epithelial cell lines after exposure to TGF-β1 was measured by quantitative reverse transcription polymerase chain reaction and Western blot analysis.
NHLRC2 expression was detected especially in bronchiolar epithelial cells, type II pneumocytes and macrophages in normal lung. In the lungs of IPF patients, NHLRC2 was mainly expressed in hyperplastic alveolar epithelial cells lining fibroblast foci and honeycombs. NHLRC2 expression assessed by image analysis was higher in IPF compared to controls (p < 0.001). Ever-smokers had more prominent NHLRC2 staining than non-smokers (p = 0.037) among IPF patients. TGF-β1 exposure did not influence NHLRC2 levels in lung cell lines.
NHLRC2 expression was higher in IPF compared to controls being widely expressed in type II pneumocytes, macrophages, bronchiolar epithelium, and hyperplastic alveolar epithelium. Additionally, its expression was not regulated by the exposure to TGF-β1 in vitro. Further studies are needed to clarify the role of NHLRC2 in IPF.
NHL 重复包含蛋白 2（NHLRC2）的变异体与儿童早期严重纤维化间质性肺病有关，并且 NHLRC2 已被列为快速和缓慢进展性特发性肺纤维化（IPF）患者之间差异表达的基因。然而，其在人肺组织中的细胞类型特异性定位尚不清楚。本研究旨在评估 NHLRC2 mRNA 和蛋白在肺组织样本不同细胞类型中的表达，并研究转化生长因子（TGF）-β1 暴露对体外 NHLRC2 表达的影响。
通过免疫组织化学（50 例 IPF，10 例对照）和原位杂交（8 例 IPF，3 例对照）研究肺组织样本中的 NHLRC2 表达。使用图像分析软件对 NHLRC2 免疫组织化学表达进行定量，并与患者的临床和吸烟数据相关联。通过定量逆转录聚合酶链反应和 Western blot 分析测量 TGF-β1 暴露后原代基质和小气道上皮细胞系中的 NHLRC2 表达水平。
在正常肺中，NHLRC2 表达主要在细支气管上皮细胞、Ⅱ型肺泡细胞和巨噬细胞中检测到。在 IPF 患者的肺中，NHLRC2 主要在纤维化灶和蜂窝状肺中增生的肺泡上皮细胞中表达。与对照组相比，IPF 患者的 NHLRC2 表达通过图像分析评估更高（p<0.001）。在 IPF 患者中，吸烟者的 NHLRC2 染色比非吸烟者更明显（p=0.037）。TGF-β1 暴露不会影响肺细胞系中的 NHLRC2 水平。
与对照组相比，IPF 中的 NHLRC2 表达更高，在Ⅱ型肺泡细胞、巨噬细胞、细支气管上皮和增生的肺泡上皮中广泛表达。此外，其表达不受体外 TGF-β1 暴露的调节。需要进一步研究来阐明 NHLRC2 在 IPF 中的作用。
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