Variable roles of the H1‐H3 receptors and PKC in histamine‐induced barrier dysfunction in cultured endothelial cells from different sources (672.6)

Abstract

We tested the hypothesis that histamine‐induced endothelial barrier dysfunction requires different receptors and signaling pathways depending upon endothelial cell (EC) source. Changes in barrier function elicited by 10 μM histamine were compared between human umbilical vein EC (HUVEC) and human dermal microvascular EC (HMVEC‐D) monolayers, using determination of transendothelial electrical resistance (TER). H1, H2, and H3 receptors were blocked with 10 μM mepyramine, 10 μM cimetidine, and 0.01‐1 μM ciproxifan, respectively. Inhibitors of PKC (GFX109203X), PI3K (PI828) and phospholipase C (U73122) were used to evaluate downstream signals. Western blots and immunofluorescence microscopy analysis demonstrated H1, H2, and H3 expression in both EC types. Blockade of H1, H2, or H3 significantly inhibited the histamine‐induced decrease in TER in HMVEC‐D. In contrast, only blockade of H1 significantly attenuated the histamine‐induced drop in TER in HUVEC. Inhibition of either PKC or PI3K significantly attenuated histamine‐induced barrier dysfunction in HUVEC, but combined inhibition of both was required to attain significant attenuation in HMVEC‐D. Inhibition of PLC also inhibited the histamine‐induced decrease in TER in HMVEC‐D, but interestingly, combined PLC and PKC inhibition did not. This study suggests a common role for H1, but differential roles for H2 and H3 in histamine‐induced endothelial barrier dysfunction among different endothelial cell types. In addition, PKC appears to have either a promoting or inhibitory role depending on the endothelial cell source. Supported by NIH R01HL098215.Grant Funding Source: NIH R01HL098215