Pang, J.; Do, L. N. H.; Delgado, E. D.; Zhao, J.; Flynn, L.; Liu, H.; Autieri, M.; Yang, X.; Liu, X.

Lymphedema is a chronic disease characterized by impaired lymph drainage and accumulation of protein-rich interstitial fluid, which progresses to develop irreversible fibrosis. Importantly, effective therapies and treatments are lacking to alleviate and mitigate the disease. The pathological inflammation and fibrogenesis underlying lymphedema prompted us to evaluate a preclinical medicine IVA337, a pan-peroxisome proliferator-activated receptor (PPAR) agonist that improves liver fibrosis in patients with metabolic dysfunction-associated steatohepatitis (MASH) by activating three PPAR isoforms (, {beta}/{delta}, {lambda}), which play critical roles in lipid metabolism, anti-inflammation responses, and anti-fibrogenesis. Here, we investigate the therapeutic effects of IVA337 during the early stage of surgery-induced secondary lymphedema in mice and explored the underlying mechanisms. IVA337 administration alleviated lymphedema progression, improved lymphatic drainage, reduced dermal thickness, and resolved lymphatic vessel dilation. Mechanistically, IVA337 suppressed the TGF{beta}/SMAD2/3 signaling pathway, reduced immune cells infiltration, and improves lymphatic vessels integrity. In human dermal lymphatic endothelial cells (HDLECs), IVA337 attenuated TGF{beta} induced SMAD2/3 phosphorylation and preserved the expression of cell junction Claudin5, reduced VE-Cadherin-stained cell-cell gaps. Collectively, our findings demonstrate that IVA337 protects against early stage lymphedema by inhibiting TGF{beta}/SMAD2/3-mediated inflammatory and fibrotic responses. This study provides a potential therapeutic strategy to improve lymphatic function during the early phase of lymphedema and prevent progressive fibrosis in patients with lymphedema and related disorders.