Background Interleukin-17 (IL-17) has been cast as a major player in angiopoiesis of carcinoma, but its role in hepatic haemangioma is not entirely clear.

Aim The aim of this study is to address the expression levels and the molecular mechanism underlying the role of IL-17 on hepatic haemangioma progression.

Methods and Results 20 hepatic haemangioma patients and 15 healthy subjects were included in this study. IL-17 mRNA levels were examined by PCR-based methods and protein levels by western blot. We observed a significant increase in tissue IL-17 mRNA and protein levels in hepatic haemangioma compared to normal liver tissue. Matrix metalloproteinase protein levels were slightly elevated in haemangiomas compared to normal, and IL-6 and phospho-stat3 levels were markedly elevated. However, no differences in mRNA levels of angiogenesis-associated cytokines such as vascular endothelial growth factor were seen in hepatic haemangiomas compared to normal cases taken from donor livers at the time of organ harvest. IL-17 was localised to CD4-positive cells by flow cytometry and to stromal cells and endothelial cells by immunohistochemistry. Owing to the absence of an animal model of haemangioma, we examined the effects of IL-17 on angiogenesis-related functions of vascular endothelial cells in vitro. Notably, IL-17, when added to cell cultures of human umbilical cord-derived endothelial cells, had an effect on the secretion of IL-6 and p-stat3.

Conclusions Based on these findings, we propose that IL-17 may mediate the angiogenesis in a IL-6-Stat3-dependent manner and play an important role in the pathophysiology of hepatic haemangioma.