Abstract Rationale Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive disease of the lung parenchyma. Current standard of care treatment Pirfenidone and Nintedanib slow down disease progression but cause severe gastrointestinal side effects. Recently, the role of pulmonary stem cell populations such as aberrant basaloid cells and ATII cells in IPF disease etiology has shifted into focus. A promising approach to interfere in dysregulated transcriptional pathways within these cell populations is to use small interfering RNAs (siRNAs) to silence genes encoding transcription factors and regulatory proteins involved in the early stages of IPF development. Here, we demonstrate that siRNA treatment can reduce relevant fibrotic markers in human fibrotic lung tissue. Methods We designed 30 different siRNA candidates targeting genes that have been shown to be dysregulated in epithelial stem cell populations in early IPF (incl. MMP7, HNF4A, P-Sel, RUNX2). We screened the target engagement of these siRNA candidates using a fluorescent reporter assay. The highest-ranking siRNA candidates were tested for anti-fibrotic treatment in human Precision-Cut Lung Slices (hPCLS) from end-stage fibrosis or induced early-onset fibrosis. We measured pulmonary fibrosis markers proCOL1A1, FN1, MMP7, MMP9, VEGFa, and PAI1 in the treated hPCLS using ELISA. Results 17 out of 30 candidates tested demonstrated a knockdown efficiency of 85 % in vitro. From these, we identified seven lead candidate siRNAs (si1-7) targeting MMP7, HNF4A, P-Sel, and RUNX2. 1 µM treatment with candidates si1 and si7 efficiently reduced proCOL1A1 from 96000 (±34569) to 56100 (±31380) and 25042 (±3472) pg/mL; and FN1 from 33.37 (±15.7) to 21.14 (±5.9) and 16.05 (±3.7) pg/mL, respectively, in hPCLS from end-stage fibrotic tissue. We further demonstrated successful induction of fibrosis in non-fibrotic human lung tissue by elevated Col1A1, PAI1, MMP7, and FN1 levels upon cytokine stimulation. These markers could be significantly reduced by prophylactic treatment with 1 µM si1 and si7. Conclusion These findings support the therapeutic potential of siRNA-mediated modulation of dysregulated regenerative pathways in epithelial stem cell populations in the early development of IPF. This abstract is funded by: SPRIND
Barbosa et al. (Fri,) studied this question.