Distinct transcriptional regulation of the Wnt and TGFβ signaling families associated with wound healing and fibrotic outcomes to lens injury

Abstract

Posterior capsule opacification (PCO) is a fibrotic complication of cataract surgery caused by aberrant repair of residual lens cells. It remains unclear how the lens injury response shifts toward a pathological repair process. Here, we performed a transcriptional analysis of two major pro-fibrotic pathways, the TGF-β superfamily and Wnt signaling pathways to determine how they are differentially regulated during regenerative wound healing versus fibrosis in a lens injury model. For these studies, RNA sequencing was performed on an ex vivo lens explant system that models post-surgical healing within regenerative and fibrotic microenvironments, from 0 to 3 days post-injury. Fibrotic conditions were marked by increased expression of TGF-β ligands, receptors, SMAD3, and extracellular regulators, LTBP1 and THSB1 consistent with strong activation of canonical TGF-β signaling. In contrast, BMP signaling during wound healing, was characterized by early induction of BMP receptors, SMAD1, and downstream ID genes, indicative of robust activation while in fibrosis, BMP ligands and receptors increased but downstream signaling was blunted potentially by elevated expression of BMP inhibitors. Inhibition of ID proteins using a pan-ID inhibitor, impaired both wound closure and myofibroblast formation, supporting a role for ID protein function in both contexts. Distinct Wnt ligands and FZD receptors were upregulated in regenerative vs. fibrotic repair contexts to drive canonical/noncanonical Wnt signaling. Fibrosis favored upregulation of the Wnt/Ca²⁺ pathway and multiple RSPO's associated with Wnt activation. These findings reveal new insight into the transcriptional regulation of the TGF-β and Wnt family pathway components and modulators associated with programming distinct outcomes to lens injury.