ABSTRACT
Title
PPAR-α mediates the anti-inflammatory effect of simvastatin in an experimental model of zymosan-induced multiple organ failure
Authors
M. Donniacuo1, B. Rinaldi1, E. Esposito2,3, A. Capuano1, L. Sodano1, E. Mazzon2, D. Di Palma1, I. Paterniti3, G. Gritti1, S. Cuzzocrea2,3, F. Rossi1.
1Dept of Experimental Medicine, Section of Pharmacology “L.Donatelli”, Excellence Centre on Cardiovascular Diseases, Second University of Naples, Italy.
2IRCCS Centro Neurolesi "Bonino-Pulejo", Messina, Italy.
3Dept of Clinical and Experimental Medicine and Pharmacology, School of Medicine, University of Messina, Italy.
1Dept of Experimental Medicine, Section of Pharmacology “L.Donatelli”, Excellence Centre on Cardiovascular Diseases, Second University of Naples, Italy.
2IRCCS Centro Neurolesi "Bonino-Pulejo", Messina, Italy.
3Dept of Clinical and Experimental Medicine and Pharmacology, School of Medicine, University of Messina, Italy.
Abstract
Sepsis is a very complex inflammatory syndrome that leads to multiple organ dysfunction syndrome (MODS), involving inflammatory cascade activation and endothelium dysfunction (Remick et al., 2009). A well-tested experimental model of human MODS is zymosan-induced non-septic shock. Zymosan is a non-bacterial, non-endotoxic agent that produces acute peritonitis and multiple-organ failure characterized by functional and structural changes in the liver, intestine, lung, and kidneys. Simvastatin is a lipid-lowering drug that inhibit 3-hydroxy-3-methylglutaryl co-enzyme A reductase, and it is one of the first-line treatment for the prevention of coronary artery disease and atherosclerosis. Simvastatin exerts important immunomodulatory and anti-inflammatory effects on endothelium, platelets, smooth muscle cells and inflammation by decreasing the expression of proinflammatory transcriptional factors such as nuclear factor (NF)-κB that results in decreased expression of cytokines, chemokines and nitric oxide synthase (iNOS) (Jasinska et al., 2007). One of the molecular pathway involved in the antinflammatory activity of statins includes peroxisome proliferator-activated receptor (PPAR)α. PPARs are nuclear receptors mainly involved in the regulation of lipid metabolism. They also exert anti-inflammatory activities by negatively interfering with proinflammatory signaling pathways including NF-κB in various experimental models while the absence of PPARα increases the degree of multiple organ failure induced by zymosan in mice (Di Paola et al., 2006). For this purpose, in the present study we investigate the role of the nuclear receptor PPARα in the anti-inflammatory effects of simvastatin in a murine model of non-septic shock induced by zymosan.
To this end we used mice with a targeted disruption of the PPARα gene (PPARαKO) and wild-type littermate controls (PPARαWT).
Mice were allocated to two main groups: PPARαWT (n=40) and PPARαKO (n=40). Each group was randomly divided in two subgroups: (1) the SHAM WT group (n=20) and (2) theZYMOSAN WT (ZYM WT) group (n=20) constituted by PPARαWT mice treated intraperitoneally (i.p.) with the vehicle (saline solution 0.9 % NaCl) or zymosan (500 mg/kg), respectively; (3) the SHAM KO group (n=20) and (4) theZYMOSAN KO (ZYM KO) group(n=20)constituted by PPARαKO mice treated i.p. with the vehicle or zymosan. One and six hours after administration of vehicle or zymosan, all four subgroups (n=80) were treated with simvastatin 5 or 10 mg/kg i.p. Eighteen hours after the study onset, lung, liver, kidney, intestine and plasma were obtained from all the animals. Simvastatin induced a dose-dependent increase of PPARα expression, evaluated by RT-PCR, in all tissues of ZYM WT mice compared to the SHAM WT mice.
Acute peritonitis occurred 18 h after zymosan administration as shown by the production of turbid exudate. The absence of the functional PPARα receptor in ZYM KO mice significantly enhanced exudate formation. Treatment with simvastatin significantly and dose-dependently reduced exudate formation in ZYM WT but not in ZYM KO mice. Zymosan also induced a severe inflammatory response characterized by an increased nuclear p65, polymeric adenosine diphosphate-ribose (PAR), nitric oxide synthase, nitrotyrosine, TNF-α, IL-1β, NO expression and organ injury.
Simvastatin treatment in a dose-dependent manner significantly reduced the release of these mediators and improved organ injury in lung, liver, kidney and intestine. These effects were more evident in PPARαWT mice compared to PPARαKO mice.
In conclusion, simvastatin exerts pleiotropic effects in a model of zymosan-induced non-septic shock by preventing, at molecular and cellular level, organ damage consequent to a powerful inflammatory response. One of these pleiotropic effects could involve an increased PPARα expression.
To this end we used mice with a targeted disruption of the PPARα gene (PPARαKO) and wild-type littermate controls (PPARαWT).
Mice were allocated to two main groups: PPARαWT (n=40) and PPARαKO (n=40). Each group was randomly divided in two subgroups: (1) the SHAM WT group (n=20) and (2) theZYMOSAN WT (ZYM WT) group (n=20) constituted by PPARαWT mice treated intraperitoneally (i.p.) with the vehicle (saline solution 0.9 % NaCl) or zymosan (500 mg/kg), respectively; (3) the SHAM KO group (n=20) and (4) theZYMOSAN KO (ZYM KO) group(n=20)constituted by PPARαKO mice treated i.p. with the vehicle or zymosan. One and six hours after administration of vehicle or zymosan, all four subgroups (n=80) were treated with simvastatin 5 or 10 mg/kg i.p. Eighteen hours after the study onset, lung, liver, kidney, intestine and plasma were obtained from all the animals. Simvastatin induced a dose-dependent increase of PPARα expression, evaluated by RT-PCR, in all tissues of ZYM WT mice compared to the SHAM WT mice.
Acute peritonitis occurred 18 h after zymosan administration as shown by the production of turbid exudate. The absence of the functional PPARα receptor in ZYM KO mice significantly enhanced exudate formation. Treatment with simvastatin significantly and dose-dependently reduced exudate formation in ZYM WT but not in ZYM KO mice. Zymosan also induced a severe inflammatory response characterized by an increased nuclear p65, polymeric adenosine diphosphate-ribose (PAR), nitric oxide synthase, nitrotyrosine, TNF-α, IL-1β, NO expression and organ injury.
Simvastatin treatment in a dose-dependent manner significantly reduced the release of these mediators and improved organ injury in lung, liver, kidney and intestine. These effects were more evident in PPARαWT mice compared to PPARαKO mice.
In conclusion, simvastatin exerts pleiotropic effects in a model of zymosan-induced non-septic shock by preventing, at molecular and cellular level, organ damage consequent to a powerful inflammatory response. One of these pleiotropic effects could involve an increased PPARα expression.