HB-EGF stimulates eNOS expression and nitric oxide production and promotes eNOS dependent angiogenesis

Heparin-binding epidermal growth factor-like growth factor is essential for preservation of gut barrier function after hemorrhagic shock and resuscitation in mice

BACKGROUND

The aim of the current study was to determine the role of heparin-binding (HB) epidermal growth factor (EGF)-like growth factor as a mediator of gut barrier function after hemorrhagic shock and resuscitation (HS/R) in mice.

METHODS

HS/R was induced in HB-EGF knockout (KO) and wild-type (WT) mice. Intestinal histologic injury scores, intestinal epithelial cell apoptosis, and gut barrier function were determined. Statistical analyses were performed using linear mixed models with P<.05 considered significant.

RESULTS

All mice subjected to HS/R had significantly increased intestinal histologic injury scores, apoptosis indices, and intestinal permeability compared with mice subjected to sham operation. Compared with WT mice, HB-EGF KO mice subjected to HS/R had significantly increased histologic injury (mean injury grade, 4.5 +/- 1 vs 2.75 +/- 0.5 at 3 hours of resuscitation; P<.05), increased apoptosis indices (mean apoptosis index, 6.84 +/- 1.95 vs 3.24 +/- 1.00 at 3 hours of resuscitation; P < .05), and increased mucosal permeability (FD4 clearance 78 +/- 18.91 vs 47.75 +/- 8.06 nL/min/cm(2) at 3 hours of resuscitation; P<.05).

CONCLUSION

HB-EGF is essential for the preservation of gut barrier function after HS/R. These findings support the clinical use of HB-EGF in protection of the intestines from disease states associated with intestinal hypoperfusion injury.

Heparin-binding EGF-like growth factor is a potent dilator of terminal mesenteric arterioles

OBJECTIVE

We have previously shown that heparin-binding EGF-like growth factor (HB-EGF) protects the intestines from multiple forms of injury via direct cytoprotective effects on the intestinal mucosa. In this study, we examined the effects of HB-EGF on the hemodynamics of intestinal arterioles, the major resistance vessels that regulate blood flow to the intestines, as an additional mechanism of HB-EGF-mediated intestinal protection.

METHODS

The hemodynamic effects of HB-EGF in rodent terminal mesenteric arterioles and human submucosal arterioles were examined ex vivo using a video dimension analyzer. Cultured human intestinal microvascular endothelial cells (HIMEC) were used to elucidate the mechanisms of HB-EGF-induced vasodilation.

RESULTS

HB-EGF significantly increased vessel diameter under conditions of increasing intraluminal pressure and increased flow rate. These HB-EGF-mediated vasodilatory effects were observed in terminal mesenteric arterioles from adult rats and 3 day old rat pups. These effects were confirmed in submucosal arterioles from human intestine. Furthermore, HB-EGF significantly reduced endothelin-1-induced mesenteric arteriolar vasoconstriction. The vasodilatory effects of HB-EGF were blocked by ET(B) receptor antagonism in adult rat arterioles, and also by nitric oxide synthase inhibition in rat pup and human infant arterioles. In HIMEC, HB-EGF significantly increased endothelin B (ET(B)) receptor protein expression and provoked intracellular calcium mobilization.

CONCLUSIONS

HB-EGF is a potent vasodilator of the intestinal microvasculature, further supporting its use in diseases manifested by decreased intestinal blood flow, including necrotizing enterocolitis.