As an endothelium destabilizer, CD82 facilitates vascular leakage by disrupting endothelial barrier and inhibiting its recovery during inflammation. AC at EC surface primes and promotes vascular leakage, mediates the effect of CD82 or TEMD on inflammation, and can be regulated specifically by i) tetraspanins or TEMDs, ii) ORP-mediated transfer of cholesterol, iii) environmental cholesterol, and iv) statin. Thus, tetraspanin-AC interaction and subcellular cholesterol compartmentalization tune the balances between antagonistic signaling axes of Cdc42 versus RhoA, to alter vascular leakage in inflammation. Equally important, we demonstrated anti-vascular leakage and anti-inflammation roles of i) AC reduction and ii) FARP1-Cdc42 elevation/activation in animal models, with promising translational and clinical prospects.