Abstract Rationale It is well established that signaling between the ATII cells and neighboring fibroblasts via the WNT pathway is required for stem cell niche homeostasis and activation in the context of regeneration/repair. As the WNT pathway is known to be dysregulated in COPD, sought to identify potential culprit mediators of WNT seen in emphysematous tissue of patients with COPD. We interrogated a large human ATII-enriched scRNA sequencing dataset and found one WNT antagonist was consistently upregulated specifically in the ATIIs of patients with COPD: WNT Inhibitory Factor-1 (WIF1). Methods We preformed immunofluorescence (IF) and RNAscope staining of archival lung tissue on n = 5 COPD and healthy donors. Beas-2bs epithelial cells and primary fibroblasts (n = 3) were treated with 100ng/ml WIF1 in the presence and absence of WNT3a (canonical WNT agonist) and WNT5a (non-canonical WNT agonist) conditioned media for 6hrs followed by RNA expression and unbiased bulk RNA sequencing. Results WIF1 expression was significantly upregulated in ATII cells from COPD lungs compared to healthy donors, both in multiple publicly available scRNAseq datasets and confirmed in freshly isolated ATIIs from COPD and donor lungs. Changes at the protein level were confirmed via WIF1 IF staining and co-localization with HTII-280 in whole lung tissue sections. Treatment with WIF1 strongly downregulated the EGFR/MAPK pathway including: SPRY4, DUSP4, and CCND1. Furthermore, a number of genes known to be dysregulated in COPD were found to be differentially regulated with WIF1 treatment suggesting WIF1 may play a role across several pathways. These include CTGF - an ECM regulator proposed as a serum biomarker for COPD, F3 - key member of coagulation cascade and marker of inflammation in COPD, and ULK1 - a mediator of mitophagy upregulated in COPD. Furthermore, while primary human fibroblasts demonstrated significant changes related to WNT agonism, they were relatively protected from WIF1 regulation by endogenous expression of WNT antagonists including SFRP1, and DKK1/DKK3. Conclusions We identified the WNT pathway antagonist, WIF1 as a novel mediator of disturbed WNT signaling in the ATII/fibroblast stem cell niche in COPD. The changes in gene expression on treatment with WIF1 suggest that this WNT antagonist may act to disrupt pathways that ultimately result in emphysema pathogenesis. This abstract is funded by: NIH T32
Allbright et al. (Fri,) studied this question.