CSP7, a caveolin-1–derived peptide, targets injured alveolar epithelial cells and activated lung fibroblasts to mitigate pulmonary fibrosis.

Leptomeningeal disease occurs when cancer cells migrate into the ventricles of the brain and spinal cord and then colonize the meninges of the central nervous system. The triple-negative subtype of breast cancer often progresses toward leptomeningeal disease and has a poor prognosis because of limited treatment options. This is due, in part, to a lack of animal models with which to study leptomeningeal disease. Here, we developed a translucent zebrafish casper (roy-/-; nacre-/-) xenograft model of leptomeningeal disease in which fluorescent labeled MDA-MB-231 human triple-negative breast cancer cells are microinjected into the ventricles of zebrafish embryos and then tracked and measured using fluorescent microscopy and multimodal plate reader technology. We then used these techniques to measure tumor area, cell proliferation, and cell death in samples treated with the breast cancer drug doxorubicin and a vehicle control. We monitored MDA-MB-231 cell localization and tumor area, and showed that samples treated with doxorubicin exhibited decreased tumor area and proliferation and increased apoptosis compared to control samples.

Alveolar inflammation, elevated interleukin-17A (IL-17A), and fibrin deposition are common features in all forms of lung injury followed by fibrotic repair. Type II alveolar epithelial cell (AEC) viability, regulated by tumor suppressor protein p53 and changes in uPA-mediated fibrinolysis, has been linked to lung injury and pulmonary fibrosis (PF). Nevertheless, mechanistic details linking increased IL-17A with p53 and PAI-1 to lung injury and remodeling remain unclear. We found that IL-17A and its receptor (IL-17RA) are induced during various lung injuries. IL-17A augments IL-17RA, p53 and downstream PAI-1 with a concurrent decrease in uPA and its receptor (uPAR) in AECs. These changes promote AEC apoptosis, alveolar injury and PF. In addition, IL-17A causes a dose-dependent increase in IL-17RA and profibrogenic markers in lung fibroblasts (LFs), suggesting myofibroblast differentiation. We further found that inhibition of IL-17A by caveolin-1 scaffolding domain peptide (CSP) or its 7-mer deletion fragment (CSP7) inhibits AEC apoptosis, lung inflammation, and profibrogenic markers in LFs and PF. Further, treatment of mice with bleomycin-induced lung injury using CSP7, an anti-IL-17A antibody, or an IL-17RA blocking antibody attenuates total lung hydroxyproline and soluble collagen content, as well as levels of profibrogenic markers. These observations support the role of IL-17A/IL-17RA signaling in lung injury and post-injury remodeling.