NHLRC2 mRNA and protein expression in idiopathic pulmonary fibrosis

Abstract

Background: Mutations in NHL repeat-containing protein 2 (NHLRC2) have been associated with severe interstitial lung disease (Uusimaa, J. et al. Acta Neuropathol 2018;135:727-742). NHLRC2 has been listed as a differentially expressed gene when comparing rapidly and slowly progressing idiopathic pulmonary fibrosis (IPF) patients (Boon, K. et al. PloS one 2009;4:e5134). Aims and objectives: The aim of this study was to evaluate the cell-specific expression of NHLRC2 mRNA and protein in lung tissue samples and also to investigate the effect of transforming growth factor (TGF)-β1 exposure on NHLRC2 expression in lung cells. Methods: NHLRC2 expression in lung tissue samples was studied by mRNA in situ hybridization (6 IPF and 3 controls) and immunohistochemistry (49 IPF and 13 controls). The expression of NHLRC2 in both stromal and small airway epithelial cell lines after exposure to 5 ng/ml TGF-β1 was measured by quantitative real-time reverse transcriptase polymerase chain reaction and Western blotting. Results: The strongest mRNA and protein expression of NHLRC2 was detected in bronchiolar epithelial cells and type II pneumocytes in normal lung. In IPF NHLRC2 was mainly expressed in hyperplastic alveolar epithelial cells lining fibroblast foci and honeycombs. TGF-β1 exposure did not have effect on NHLRC2 mRNA or protein expression either in stromal or epithelial cells. Conclusions: NHLRC2 was widely expressed in hyperplastic alveolar epithelial cells in IPF, but its expression was not regulated by the exposure to TGF-β1.