Induction of Endothelial Nitric Oxide Synthase Expression by IL-17 in Human Vascular Endothelial Cells: Implications for Vascular Remodeling in Transplant Vasculopathy

Abstract

IL-17 is a signature cytokine of Th17 cells, a recently described subset of effector CD4 T cells implicated in the development of several pathologies. We have examined the role of IL-17 in regulating endothelial NO synthase (eNOS) expression in human vascular endothelial cells (ECs) because of the key role of eNOS in determining the pathological outcome of immune-mediated vascular diseases. In cultured ECs, IL-17 increased expression of eNOS, eNOS phosphorylation at Ser1177, and NO production. The induction of eNOS expression by IL-17 was prevented by the pharmacological inhibition of NF-κB, MEK, and JNK, as well as by small interfering RNA-mediated gene silencing of these signaling pathways. The expression of IL-17 was then examined by immunohistochemistry in human arteries affected by transplant vasculopathy (TV), a vascular condition that is a leading reflection of chronic heart transplant rejection. IL-17 was expressed by infiltrating leukocytes in the intima of arteries with TV, and the majority of IL-17–positive cells were T cells. The number of IL-17–positive cells was not correlated with the intima/media ratio, but was negatively correlated with the amount of luminal occlusion. There was also a significant positive correlation between the number of IL-17–positive cells and the density of eNOS-expressing luminal ECs in arteries with TV. Altogether, these findings show that IL-17 induces the expression of eNOS in human ECs and that this may facilitate outward expansion of arteries afflicted with TV.

Targeting IL-17 attenuates hypoxia-induced pulmonary hypertension through downregulation of β-catenin

“…Our data showed that the immunoreactivity of IL-17 was located predominantly in the innermost medial layer of the pulmonary arterioles, so we investigated whether IL-17 affects the functions of PAECs. An MTT analysis showed that the maximal proliferation response by PAECs occurred with10 ng/mL IL-17 (figure 4A), which we chose for subsequent experiments as the stimulating concentration, as it was consistent with a previous study 14. Correspondingly, a BrdU incorporation assay showed that 10 ng/mL rhIL-17 increased the percentage of BrdU-stained PAECs (P4, S phase of the cell cycle), indicating IL-17-induced the proliferation of PAECs (figure 4B).…”

Potassium Channel Subfamily K Member 3 (KCNK3) Contributes to the Development of Pulmonary Arterial Hypertension

“…39 Interestingly, IL-17 binds to its receptor composed of IL-17RA and IL-17RC subtypes, leading to activation of the canonical ERK1/2, phosphoinositide 3-kinase-Akt, c-Jun N-terminal kinase, and p38 mitogen-activated protein kinase pathways. 40 We have shown that KCNK3 expression was reduced in patients with iPAH and hPAH and in MCT-PH rats. Interestingly, we have also previously demonstrated that PH induced by cyclophosphamide in rats is associated with a 70% reduction in KCNK3 expression.…”

Positive Feedback Regulation of Human Inducible Nitric-oxide Synthase Expression by Ras Protein S-Nitrosylation

“…Transfection of Cells-A549 cells were harvested by trypsinization, and 1 ϫ 10 6 cells were transfected with 6 g of wild type or 6 g of C118S Ras plasmid using an Amaxa nucleofector as per the manufacturer's instructions (Lonza) and as described previously (45). The wild-type (WT) and C118S Ras plasmids were kindly provided by Dr. Kenneth Tang (Cornell University).…”