Apelin attenuates UVB-induced edema and inflammation by promoting vessel function

The role of apelin in vascular regulation is well established, particularly in blood vessels. However, its involvement in lymphatic vessel function remains underexplored. Prior research has shown apelin's influence on endothelial migration and vessel formation. Yet, no prior work had resolved its specific effects on lymphatic vessels during inflammation. This gap motivated researchers to investigate apelin's potential in modulating lymphatic responses. UVB-induced inflammation serves as a model for studying skin barrier dysfunction and edema. The APJ receptor's expression in lymphatic endothelium suggests a possible regulatory role. But the mechanisms by which apelin affects lymphatic permeability were unclear. This study aimed to clarify apelin's function in lymphatic vessel stability during inflammation.

The study aimed to determine whether apelin influences lymphatic vessel function in inflamed skin. Researchers focused on UVB-induced inflammation as a model system. They hypothesized that apelin might stabilize lymphatic vessels and reduce edema. To test this, they examined apelin's effects on lymphatic endothelial cells in vitro. They also used transgenic mice to observe in vivo responses. The goal was to assess apelin's role in vessel permeability and inflammation. By analyzing migration, cord formation, and permeability, they sought to link apelin to lymphatic function. Their findings could inform new strategies for managing inflammatory skin conditions.

Researchers first evaluated APJ receptor expression in human lymphatic endothelial cells. They then tested apelin's effects on cell migration and cord formation in vitro. Permeability assays were used to measure apelin's impact on endothelial stability. Transgenic mice with apelin under keratin 14 control were developed for in vivo studies. UVB exposure was applied to induce inflammation and edema in these mice. Researchers measured edema, macrophage infiltration, and vessel size in response to UVB. They also assessed lymphatic vessel permeability in inflamed skin. The apelin/APJ signaling pathway was analyzed to determine its role in these effects.

Apelin induced lymphatic endothelial cell migration and cord formation in a dose-dependent manner. Permeability assays showed that apelin reduced endothelial cell leakage. Transgenic mice with apelin overexpression had less UVB-induced edema than controls. These mice also exhibited fewer CD11b-positive macrophages in inflamed skin. Apelin signaling inhibited UVB-induced enlargement of both lymphatic and blood vessels. Lymphatic hyperpermeability in inflamed skin was significantly reduced in transgenic mice. These effects suggest apelin stabilizes lymphatic vessels during inflammation. The results support apelin's potential as a therapeutic target for UVB-related inflammation.

The study found that apelin stabilizes lymphatic vessels in inflamed skin. Apelin's effects were observed in both in vitro and in vivo models. Transgenic mice with apelin overexpression showed reduced edema and macrophage infiltration. The apelin/APJ pathway appears to regulate lymphatic vessel permeability during UVB exposure. These findings suggest apelin may help prevent UVB-induced inflammation. The researchers propose that apelin could be a suitable target for therapeutic strategies. Their results highlight the importance of apelin in lymphatic function. No prior work had resolved these specific effects of apelin in lymphatic vessels.