Abstract 12450: Trpv1 Responses to Heat and Induces Il-6 Production in Skeletal Muscle Cells
Introduction: Interluekin-6 (IL-6) is released from skeletal muscle cells and induced by exercise, heat, catecholamine, glucose, lipopolysaccharide, reactive oxygen species, and inflammation. However, the mechanism, which induces release of IL-6 from skeletal muscle cells, remains unknown. Thermo-sensitive transient receptor potential subfamily V member 1 (TRPV1) plays vital roles in cellular functions.
Hypothesis: We hypothesized thatTRPV1 senses heat, transmits a signal into the nucleus, and produces IL-6. We investigated the underlying mechanisms, where skeletal muscle cells sense heat and respond to it.
Methods: Mouse C2C12 myoblast cells were cultured at 37°C under 5% CO2 atmosphere. When cells were exposed to heat, culture dishes were placed in another incubator which was preset to an environment temperature of 39°C, 40°C, 41°C, and 42°C. The calcium influx concentration was measured by a fura-2 fluorescence dual-wavelength excitation method. The IL-6 mRNA expression level of IL-6 was analyzed by using real-time PCR. The protein density level of IL-6 released from myoblast cells was analyzed by using an ELISA. The phosphorylation level of TRPV1 was analyzed by using western blotting.
Results: When myoblast cells were exposed to temperatures ranging from 37 degrees C to 42 degrees C for two hours, the mRNA expression of IL-6 increased in a temperature-dependent manner. Heat also increased IL-6 secretion. Heat increased the intracellular calcium flux temperature-dependently. TRPV1 agonists, capsaicin and NADA, increased the intracellular calcium flux and the IL-6 mRNA expression, while TRPV1 antagonists, AMG9810 and SB366791, and the siRNA mediated knockdown of TRPV1 decreased them. Western blotting with inhibitors demonstrated that heat increased the phosphorylation levels of TRPV1 followed by PKC and CREB. PKC inhibitors, Go6983 and staurosporine, CREB inhibitors, curcumin and naphthol AS-E, and the knockdown of CREB suppressed the heat induced increases of IL-6 mRNA.
Conclusions: TRPV1 senses heat and increases IL-6 production in skeletal muscle cells through the PKC and CREB pathway. Moreover it suggests that hyperthermic conditioning is effective for the exercise therapy or rehabilitation.
Author Disclosures: S. Obi: None. T. Nakajima: None. T. Inoue: None.
- © 2016 by American Heart Association, Inc.