Super resolution microscopy analysis reveals increased Orai1 activity in asthma and cystic fibrosis lungs

Question: In diseases such as asthma and cystic fibrosis (CF), the immune response is dysregulated and the lung is chronically inflamed. Orai1 activation is required for the initiation and persistence of inflam-mation. However, Orai1 expression in the lung is poorly understood. We therefore tested the hypothesis that Orai1 expression was upregulated in asthmatic and CF lungs. Materials and methods: We used LungMAP to analyze single-cell RNAseq data of Orai1 and stromal inter-action molecule 1 (STIM1) expression in normal human lungs. We then performed RNAscope analysis and immunostaining on lung sections from normal, asthma, and CF donors. We imaged sections by confocal and super resolution microscopy, and analyzed Orai1 and STIM1 expression in different pulmonary cell types. Results: Orai1 was broadly-expressed, but expression was greatest in immune cells. At mRNA and protein levels, there were no consistent trends in expression levels between the three phenotypes. Orai1 must in-teract with STIM1 in order to activate and conduct Ca2 +. We therefore used STIM1/Orai1 co-localization as a marker of Orai1 activity. Using this approach, we found significantly increased co-localization be-tween these proteins in epithelia, interstitial and luminal immune cells, but not alveoli, from asthma and CF lungs. Orai1 also aggregates as part of its activation process. Using super resolution microscopy, we also found significantly increased Orai1 aggregation in immune cells from asthmatic and CF lungs. Conclusion: We found evidence that Orai1 was more active in asthma and CF than normal lungs. These data suggest that Orai1 is a relevant target for reducing pulmonary inflammation.(c) 2022 Published by Elsevier B.V. on behalf of European Cystic Fibrosis Society.

Automated summary

This study found that Orai1 is more active in asthma and CF than in normal lungs, indicating that it is a relevant target for reducing pulmonary inflammation.