TAK1 Prevents Endothelial Apoptosis and Maintains Vascular Integrity

TNF-α is a pleiotropic cytokine that has the potential to induce apoptosis under inflammation. How endothelial cells (ECs) are spared from this fate in inflammatory environments where TNF-α is present is not known. Here, we show that TGF-β-activated kinase 1 (TAK1) ensures EC survival and maintains vascular integrity upon TNF-α stimulation. Endothelial-specific TAK1 knockout mice exhibit intestinal and liver hemorrhage due to EC apoptosis, leading to vascular destruction and rapid death. This EC apoptosis was induced by TNF-α from myeloid cells responding to intestinal microbiota. TNF-α secretion associated with inflammation also induced vascular defects in inflamed organs. Additionally, we determined that TAK1 deletion in tumor ECs resulted in blood vessel and hence tumor regression. Our results illuminate mechanisms ensuring survival of intestinal and liver ECs under physiological conditions and ECs of other organs under inflammatory conditions that could be exploited for anti-angiogenic therapy to treat cancer. [Display omitted] •TAK1 inhibits endothelial cell death induced by TNF-α-TNFR1 signaling•Endothelial TAK1 is essential for protecting blood vessels from intestinal microbes•Under inflammation, ECs actively protect themselves from TNF-α-induced cell death•Targeting endothelial TAK1 may become an alternative for anti-angiogenic therapy Mechanisms by which endothelial cells (ECs) maintain themselves in inflammatory microenvironments remain unclear. Naito et al. show that TAK1 prevents EC apoptosis induced by TNF-α-expressing myeloid cells. TAK1 protects ECs and ensures the maintenance of vascular integrity and homeostasis under inflammatory conditions.