Summary Abnormal tumor vessels promote metastasis and impair chemotherapy. Hence, tumor vessel normalization (TVN) is emerging as anti-cancer treatment. Here, we show that tumor endothelial cells (ECs) have a hyper-glycolytic metabolism, shunting intermediates to nucleotide synthesis. EC haplo-deficiency or blockade of the glycolytic activator PFKFB3 did not affect tumor growth, but reduced cancer cell invasion, intravasation and metastasis by normalizing tumor vessels, which improved vessel maturation and perfusion. Mechanistically, PFKFB3 inhibition tightened the vascular barrier by reducing VE-cadherin endocytosis in ECs, and rendering pericytes more quiescent and adhesive (via upregulation of N-cadherin) through glycolysis reduction; it also lowered the expression of cancer cell adhesion molecules in ECs by decreasing NF-κB signaling. PFKFB3-blockade treatment also improved chemotherapy of primary and metastatic tumors.

Rapid translocation of P-selectin from WPB to the surface of endothelial cells is crucial for early neutrophil recruitment to acute inflammatory lesions. Likewise, the chemokine CXCL8/IL-8 is sorted to WPB in human endothelial cells, but little is known about its functional importance in lack of a suitable animal model. Here, we explored the distribution of the functional IL-8 homologues CXCL1/KC, CXCL2/MIP-2, and CXCL5-6/LIX in resting and inflamed murine vessels by confocal microscopy and paired immunostaining with markers of WPB, discovering that these chemokines did not localize to WPB but displayed a granular pattern in a subset of vessels in healthy skin compatible with sorting to the type 2 endothelial compartment for regulated secretion. Moreover, all chemokines colocalized with VWF and P-selectin in platelets, suggesting that their storage in platelet alpha-granules might represent an alternative source of rapidly available, neutrophil-recruiting chemokines. In conclusion, WPB appear not to be involved in regulated secretion of chemokines in the mouse, and instead, the possible existence of type 2 granules and the role of platelets in rapid leukocyte adhesion deserve further attention.

IL-33 is a novel IL-1 family member with a putative role in inflammatory skin disorders and a complex biology. Therefore, recent conflicting data regarding its function in experimental models justify a close assessment of its tissue expression and regulation. Indeed, we report here that there are strong species differences in the expression and regulation of epidermal IL-33. In murine epidermis, IL-33 behaved similar to an alarmin, being constitutively expressed in keratinocyte nuclei and rapidly lost during acute inflammation. By contrast, human and porcine IL-33 were weakly expressed or absent in keratinocytes of noninflamed skin but induced during acute inflammation. To this end, we observed that expression of IL-33 in human keratinocytes but not murine keratinocytes was strongly induced by IFN-γ, and this upregulation completely depended on the presence of EGFR ligands. Accordingly, IFN-γ increased the expression of IL-33 in the basal layers of the epidermis in human ex vivo skin cultures only, despite good evidence of IFN-γ activity in cultures from both species. Together these findings demonstrate that a full understanding of IL-33 function in clinical settings must take species-specific differences into account.