Methods: We employed BALB/c wild-type (WT), intestinal IL-9Tg and VE-specific Abl1 kinase–deficient (Cdh5Cre Abl1fl/fl) mice and pharmacologic inhibitors (Imatinib) and models of anaphylaxis to determine the requirement of Abl1 kinase in IgE-mediated reactions. Involvement of Abl1 kinase in histamine and IL-4-induced VE dysfunction we examined by electrophysiologic and permeability analyses on a human VE cell line (EA.hy926) following Abl1 kinase shRNA-lentiviral knockdown.
Results: In vitro genetic ablation of Abl1 activity revealed that histamine induced barrier dysfunction of EA.hy926 cells was dependent on Abl1 (TER (Ω/cm2) : 90.2 ± 11.0 WT ; 114.5 ± 11.8 shRNA-Abl1; p < 0.005). Imatinib pretreatment of ovalbumin (OVA)-sensitized and orally challenged mice protected the mice from anaphylaxis as the level of hypothermia (Temperature loss (ºC): -3.1 ± 0.88 vehicle vs. -0.8 ± 0.4 imatinib; p < 0.001); hypovolemic shock (hematocrit %: 65.9 ± 9.6 vehicle; 52.21 ± 2.5 imatinib; p ≤ 0.01); and diarrhea (# mice with diarrhea: 8/8 vehicle vs. 3/8 imatinib; p ≤ 0.05). IgE-MC activation in iIL-9Tg VEΔAbl1 (Tie2Cre Abl1fl/fl mice) revealed that loss of VE-restricted Abl1 expression attenuated the development of anaphylactic symptoms (maximum temperature loss: -2.6 ± 0.76 ºC iIL-9Tg VEWT; -4.5 ± 1.64 ºC VEΔAbl1; p ≤ 0.05).
Conclusions: IgE-mediated fluid extravasation in mice is mediated by a histamine-induced VE Abl1–dependent mechanism. These studies identify a new pathway for therapeutic intervention and prevention of severe FA.