C71-20 TNIK Mediates Mesenchymal Transition of Pleural Mesothelial Cells

Rationale Pleural fibrosis (PF) is a progressive respiratory disorder that lacks durably effective pharmaceutic treatment options. Pleural mesothelial to mesenchymal transition (MesoMT) is an important process that is implicated in the pathogenesis of PF. A novel small molecule inhibitor of Traf2- and Nck-interacting kinase (TNIK), INS018_055, identified through generative AI methods, has recently advanced to clinical trials in patients with idiopathic pulmonary fibrosis (IPF), yielding encouraging initial results. However, whether TNIK is involved in the modulation of MesoMT remains unclear. Methods TGF-β was applied to primary human pleural mesothelial cells (HPMCs) to induce MesoMT. Western blotting and qPCR analyses were conducted to assess alterations in the protein and mRNA expression levels of TNIK and mesothelial-to-mesenchymal transition (MesoMT) markers, specifically alpha-smooth muscle actin (α-SMA), collagen type I (Col-1), and fibronectin (FN). A pharmaceutical inhibitor of TNIK, INS018_055 and small interfering RNA (siRNA) were used to manipulate TNIK function/expression in HPMCs. Immunofluorescence staining was also performed to determine the expression of TNIK in lung tissues from mice challenged with Streptococcus pneumoniae. Results TGF-β triggered an increase in TNIK expression in HPMCs, couple with higher levels of α-SMA, Col-1, and FN. INS018_055 dose-dependently inhibited TGF-β mediated induction of MesoMT markers. Consistent with these findings, siRNA-mediated knockdown of TNIK also reduced MesoMT induced by TGF-β. INS018_055 also reversed TGFβ mediated induction of MesoMT treatment. Specifically, mesothelial cell derived myofibroblasts returned to the basal phenotype, demonstrating significantly decreased levels of α-SMA and Col-1. Mechanistically, treatment with INS018_055 blunted activation of Smad2/3 induced by TGF-β, which might account for the effects of TNIK on mediating MesoMT. The expression of TNIK was also notably elevated in fibrotic pleural surfaces of mice challenged with Streptococcus pneumoniae. These studies suggest that targeting TNIK may potentially reverse established MesoMT in vivo. Conclusions The findings from this study suggest that TNIK plays an essential role in regulating MesoMT and may serve as a novel target for PF. This abstract is funded by: NIH