019P Brighton
Winter Meeting December 2008

The modulation of sepsis by TRPV1 – influence on NO levels, ROS production and organ damage

Elizabeth S. Fernandes1, Julie E. Keeble1, Lihuan Liang1, Yanira Riffo-Vasquez2, Susan D. Brain1

1Cardiovascular Division, King’s College London, London, UK, 2The Sackler Institute of Pulmonary Pharmacology, King’s College London, London, UK

Sepsis is a major cause of mortality and thousands of people in the world are affected by it annually (Rittirsch et al., 2007). Little is known about the protective mechanisms against sepsis onset but it has been recently suggested that TRPV1 receptor could exert a protective role on lipolysaccharide (LPS)-induced sepsis (Clark et al., 2007). We now seek to increase the understanding of the role of TRPV1 in sepsis by using a murine model of polymicrobial sepsis caused by cecal ligation and puncture (CLP). All procedures were conducted in accordance with the Animals (Scientific Procedures) Act 1986. Sex and age matched male and female C57/BL6 WT+/+ and TRPV1-/- mice were utilised at 8 weeks old (N=5-8). Mice received an i.m. injection containing midazolam (2 mg/kg) and buprenorphine (10μg/kg; Vetersergic®) 15 min prior to the CLP surgery. CLP was performed according to Baker et al. (1983) with minor modifications, under isoflurane anaesthesia (2%). An abdominal incision was made, the cecum was exposed, ligated at its base and punctured once (causing 2 holes) with a 22-gauge needle. Sham-operated mice served as controls. The abdominal incision was closed and animals were given fluid resuscitation. After 24 h, animals were killed and the peritoneal lavage and the blood were collected.

CLP triggered neutrophil migration and activation into the peritoneal cavity of both WT+/+ and TRPV1-/- mice when compared to sham animals, but no difference was observed between the WT+/+ and TRPV1-/- CLP mice. CLP increased the peritoneal nitric oxide (NOx) and ROS (superoxide and H2O2) levels in WT+/+ but not in the TRPV1-/- mice. Plasma levels of creatinine, lipase and AST were indicative of kidney, pancreas and heart/liver failure, respectively. CLP only enhanced AST levels in WT+/+ mice when compared to sham groups while TRPV1-/- deletion caused an increase of all enzymes.



Table 1. Effect of the TRPV1 deletion on CLP-induced sepsis. *P<0.05; **P<0.01 compared to sham.(ANOVA followed by Newman-Keuls)
Neutrophils (x106)MPO activity (U ml’)NO (μM)Superoxide (counts min1)H2O2(μM)AST (IUl-1)Creatinine (μmol1Lipase (IUl-1)
Sham WT+’+ 0.1 ±0.1 0.8 ±0.2 0.1 ±0.1 387 ± 84 1.7 ±0.2 107 ±13 39 ±3 38 ±5
CLP WT+’+ 5.1 ±0.7 ** 3.0 ±0.5** 17.8 ±5.0 ** 1218±598 4.8 ± 1.2 * 255 ±58 ** 53 ±5 56 ± 12
Sham TRPV1 -/- 0.2 ±0.1 0.7 ±0.1 1.6 ± 1.3 292 ±45 1.9 ±0.3 76 ± 14 41 ±3 47 ±5
CLP TEPV1 -/- 5.9 ±0.96 ** 2.2 ± 0.3 ** 2.6 ± 1.3 278 ±144 2.1 ±0.5 419 ±63 ** 82 ±18 219 ±70 *

TRPV1 seems to be an important element in sepsis progression by regulating ROS generation and NOx production and controlling organ damage, but not by inhibition of neutrophil migration. Overall, our data support a pivotal role for TRPV1 in sepsis.

E.S.F is funded by CNPq (Brazil) and ARC (UK)

Baker et al. (1983). Surgery, 94: 331-5.

Clark et al. (2007). FASEB Journal, 2: 3747-3755

Rittirsch et al. (2007). J. Leukoc. Biol., 81: 137-43.