Significance Current therapies for pulmonary fibrosis (PF) focus on slowing disease progression and reducing functional decline in patients by dampening the activation of fibroblasts and other implicated cells. There is a need for strategies that target the essential cells and signaling pathways involved in disease pathogenesis. Monocyte-derived macrophages (Mo-Macs) are known to express profibrotic genes and are involved in the pathogenesis of PF. Our results show that engineered mannosylated albumin nanoparticles specifically targeted disease-inducing Mo-Macs, and further, that nanoparticles efficiently delivered small-interfering RNA against profibrotic cytokine tumor growth factor β1 to prevent bleomycin-induced lung fibrosis.

Cancer patients experience cachexia, which is characterized by extensive skeletal muscle wasting that worsens the quality of life and increases mortality. Currently, there are no approved treatments that can effectively counteract cancer cachexia. Vascular endothelial cells (ECs) are essential for maintaining tissue perfusion, nutrient supply, and preventing inappropriate transmigration of immune cells into the tissue. However, little is known about the role of the muscle vasculature in cancer cachexia. We hypothesized that endothelial dysfunction in the skeletal muscle mediates cancer cachexia. Using transgenic pancreatic ductal adenocarcinoma (PDAC) mice and a tissue clearing and high-resolution 3D-tissue imaging approach, we found that the loss of skeletal muscle vascular density precedes the loss of muscle mass. Importantly, we show that cancer cachexia patients exhibit significantly decreased muscle vascular density and severe muscle atrophy when compared to non-cancer patients. Unbiased single cell transcriptomic analyses of the muscle endothelium unveiled a unique EC population present in cachexia muscles. Increased circulating Activin-A suppresses the expression of the transcriptional co-activator PGC1α in the muscle endothelium, thus disrupting junctional integrity in the vasculature and increasing vascular leakage. Conversely, restoration of endothelial-specific PGC1α prevented the decreased vascular density and muscle loss observed in tumor-bearing mice. Our study suggests that endothelial PGC1α is essential for maintaining the integrity of the skeletal muscle vascular barrier and that restoring muscle endothelial function could be a valuable therapeutic approach to prevent or reverse cancer cachexia.