Genetic Deletion of Vascular Endothelial Growth Factor Receptor 2 in Endothelial Cells Leads to Immediate Disruption of Tumor Vessels and Aggravation of Hypoxia.

Vascular endothelial growth factor (VEGF) blockers are used widely in clinics to target various types of human cancer. Although VEGF blockers exert marked tumor suppressive effects, the therapeutic effects can be limited. Moreover, accumulating evidence shows that VEGF acts not just on endothelial cells but also on various nonendothelial cells, including tumor and immune cells, suggesting a need to revisit the bona fide action of VEGF on endothelial cells using specific genetic mouse models. Herein, tamoxifen-inducible endothelial-specific knockout mice lacking VEGF receptor 2 (Vegfr2), the major signal transducer for VEGF, were used. The initial event resulting from cessation of endothelial Vegfr2 signaling was vascular truncation and fragmentation, rather than maturation of abnormalized vessels. Although deletion of endothelial Vegfr2 suppressed intratumor hemorrhage, it enhanced hypoxia in tumor cells and reduced the number of infiltrating cytotoxic T cells, suggesting a profound reduction in intratumor blood flow. In various tissues, deletion of endothelial Vegfr2 induced regression of healthy capillaries in intestinal villi, substantiating intestinal perforation, which is one of the most common adverse effects of VEGF blockade in humans. Overall, the data suggest that some of the known effects of VEGF blockers on tumor vessels are caused by partial cessation of VEGF signaling, or by actions on nonendothelial cells. The results increase the understanding of the mechanisms underlying anti-angiogenic therapy.

Disparities in co-payments for influenza vaccine among the elderly, during the COVID-19 pandemic in Japan.

INTRODUCTION: Seasonal influenza vaccination for the elderly is highly recommended during the COVID-19 pandemic. In Japan, the amount of subsidy for influenza differs among municipalities. Thus, we investigated the amount of and variation in subsidy for influenza vaccination for the elderly in 2020. METHODS: This was an ecological study of 1,922 municipalities in Japan. The amount of subsidy for influenza vaccines for the elderly in each municipality was surveyed through websites or via telephone. Geographic and financial data for municipalities and prefectures were obtained from the open data. The amount of co-payment for the influenza vaccine and the geographical and financial status of each municipality were compared, according to the aging rate. Univariate logistic regression analysis was performed to explore factors related to the free influenza vaccine. RESULTS: Municipalities with higher aging rates tended to have higher median co-payments for vaccines in 2020. (0 yen vs 1000 yen, p < 0.001) In addition, they tended to have worse financial conditions and lower per capita incomes. A similar trend was observed in the analysis by prefecture, i.e., a higher influenza mortality rate in prefectures with a higher aging rate. Despite having lower incomes, municipalities and prefectures with higher aging populations had higher mortality rates from influenza and higher co-payments for influenza vaccination. CONCLUSIONS: In Japan, there is a disparity among elderly people; areas with an aging population have higher co-payments for influenza vaccines despite lower incomes, suggesting that the government needs to implement corrective measures to reduce this disparity.

Tumor-specific interendothelial adhesion mediated by FLRT2 facilitates cancer aggressiveness.

Blood vessel abnormalization alters cancer cell metabolism and promotes cancer dissemination and metastasis. However, the biological features of the abnormalized blood vessels that facilitate cancer progression and whether they can be targeted therapeutically have not been fully investigated. Here, we found that an axon guidance molecule, fibronectin leucine-rich transmembrane protein 2 (FLRT2), is expressed preferentially in abnormalized vessels of advanced colorectal cancers in humans and that its expression correlates negatively with long-term survival. Endothelial cell-specific deletion of Flrt2 in mice selectively pruned abnormalized vessels, resulting in a unique metabolic state termed "oxygen-glucose uncoupling," which suppressed tumor metastasis. Moreover, Flrt2 deletion caused an increase in the number of mature vessels, resulting in a significant increase in the antitumor effects of immune checkpoint blockers. Mechanistically, we found that FLRT2 forms noncanonical interendothelial adhesions that safeguard against oxidative stress through homophilic binding. Together, our results demonstrated the existence of tumor-specific interendothelial adhesions that enable abnormalized vessels to facilitate cancer aggressiveness. Targeting this type of adhesion complex could be a safe and effective therapeutic option to suppress cancer progression.