Abstract 260: Toll-like Receptor 3 (TLR3) Activation Causes Contraction Of Vascular Smooth Muscle Through ERK1/2 Pathway And Increases Blood Pressure In Mice
Emerging evidence has suggested that viral infection can trigger hypertension. TLR3, a pattern-recognition receptor of the innate immunity, is activated by double-stranded RNA (dsRNA) from viruses or necrotic tissue. Vascular smooth muscle cells express TLR3; thus we hypothesized that TLR3 activation causes an increase in ERK1/2 signaling-induced vascular contractility and subsequently increases blood pressure. Stimulation of mouse C57bl/6 aortic smooth muscle cells (ASMC) with polyinosine polycytidylic acid (Poly I:C) (10 μg/mL, 60 min), a synthetic analog of dsRNA, resulted in increased myosin light chain phosphorylation (pMLC) (2.2 fold vs. unstimulated cells, p<0.05), a marker of vascular contraction. This effect was accompanied by increased phosphorylation of caldesmon (pCaD) on Ser789 (3.35 vs. unstimulated cells, p<0.05) as well as activation of ERK1/2 (2.56 fold increase vs. unstimulated cells, p<0.05). Pre-treatment with PD98059 (50μM, 30 min), an ERK1/2 inhibitor, decreased Poly I:C-mediated phosphorylation of CaD and MLC. Treatment with Poly I:C for 24 hours downregulated TLR3 expression by 40% in ASMC (p<0.05). Vascular studies performed on a tension myograph showed that aortas from mice treated for 2 weeks with intraperitoneal injection of Poly I:C (20mg/Kg every 48 hours) exhibited increased contraction to norepinephrine compared to control mice (EMax as %of maximum KCl response: 126± 4.56% vs. 108± 1.61%, respectively). This effect was attenuated in aortas from Poly I:C mice pre-incubated with 10uM PD98059 (EMax as %of maximum KCl response: 110.6± 5.12%). Systolic blood pressure (mmHg) was higher in Poly IC mice compared with control (128 ± 2 vs 159 ± 2). Increased spleen and kidney weight (mg) were observed in Poly I:C mice (77.63 ± 4.67 vs. 127.06 ± 7.70 control and 141.10 ± 2.42 vs. 180.35 ± 8.85 control, respectively).Our results show that activation of TLR3 in VSMC causes ERK1/2-mediated phosphorylation of MLC and CaD, thereby contributing to augmented contraction and development of vascular dysfunction and hypertension. Our data provide the functional assessment of the role of TLR3 in vascular contractile events, suggesting TLR3 as a potential new therapeutic target in vascular dysfunction and regulation of blood pressure.
Author Disclosures: M. Carrillo-Sepulveda: None. T. Hardigan: None. K. Spitler: None. R. Webb: None.
This research has received full or partial funding support from the American Heart Association, Greater Southeast Affiliate (Alabama, Florida, Georgia, Louisiana, Mississippi, Puerto Rico & Tennessee).
- © 2014 by American Heart Association, Inc.