Exogenous administration of lymphangiogenic growth factors is widely used to study changes in lymphatic function in pathophysiology. However, this approach can result in off-target effects, thereby generating conflicting data. To circumvent this issue, we modulated intracellular VEGF-C signaling by conditionally knocking out the lipid phosphatase PTEN using the Vegfr3 promoter to drive the expression of Cre-lox in lymphatic endothelial cells (LECs). PTEN is an intracellular brake that inhibits the downstream effects of the activation of VEGFR3 by VEGF-C. Activation of Cre-lox recombination in adult mice resulted in an expanded functional lymphatic network due to LEC proliferation that was independent of lymphangiogenic growth factor production. Furthermore, compared with lymphangiogenesis induced by VEGF-C injection, LEC^PTEN animals had mature, nonleaky lymphatics with intact cell-cell junctions and reduced local tissue inflammation. Last, compared with wild-type or VEGF-C–injected mice, LEC^PTEN animals had an improved capacity to resolve inflammatory responses. Our findings indicate that intracellular modulation of lymphangiogenesis is effective in inducing functional lymphatic networks and has no off-target inflammatory effects.

淋巴管生成生长因子的外源性给药被广泛用于研究病理生理学中淋巴功能的变化。然而，这种方法可能会导致脱靶效应，从而产生相互矛盾的数据。为了避免这个问题，我们通过使用Vegfr3启动子有条件地敲除脂质磷酸酶 PTEN 来调节细胞内 VEGF-C 信号传导，以驱动Cre-lox的表达在淋巴管内皮细胞 (LEC) 中。PTEN 是一种细胞内制动器，可抑制 VEGF-C 激活 VEGFR3 的下游效应。由于 LEC 增殖不依赖于淋巴管生成生长因子的产生，成年小鼠中 Cre-lox 重组的激活导致功能性淋巴网络扩大。此外，与 VEGF-C 注射诱导的淋巴管生成相比，LEC ^PTEN动物具有成熟、无渗漏的淋巴管，具有完整的细胞-细胞连接并减少了局部组织炎症。最后，与野生型或 VEGF-C 注射小鼠相比，LEC ^PTEN动物解决炎症反应的能力有所提高。我们的研究结果表明，淋巴管生成的细胞内调节可有效诱导功能性淋巴网络，并且没有脱靶炎症作用。