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Antimicrobial Agents and Chemotherapy, Jan 1997, 117-121, Vol 41, No. 1
S Milano, F Arcoleo, P D'Agostino and E Cillari
We have tested whether tetracyclines (TETs) are able to protect mice from
lipopolysaccharide (LPS)-induced shock, a cytokine-mediated inflammatory
reaction. Mice, injected with a single dose of tetracycline base (TETb;
1.5, 10 and 20 mg/kg of body weight) or doxycycline (DOXY; 1.5 mg/kg), were
significantly protected from a lethal intraperitoneal injection of LPS (500
micrograms per mouse). TETs acted in early events triggered in response to
LSP; in fact, they were no longer significantly protective if injected more
than 1 h after the injection of endotoxin. LPS-treated mice protected by
TETs showed a significant inhibition of tumor necrosis factor alpha
(TNF-alpha), interleukin-1 alpha (IL-1 alpha), and nitrate secretion in the
blood, events that were directly related with the survival. In mice treated
with TETs a significant decrease of inducible nitric oxide synthase (iNOS)
activity was observed in spleen and peritoneal cells compared with that
detected in mice treated with LPS alone. Furthermore, TETs were found to
inhibit NO synthesis by peritoneal macrophages stimulated in vitro with
LPS. On the contrary, TETs were unable to decrease the ability of the
macrophages to synthesize IL-1 alpha and TNF-alpha in vitro. These results
indicate that TETs are not able to act directly on the synthesis of these
cytokines, but they may modulate other pathways that could in turn be
responsible for the inhibition of IL-1 alpha and TNF-alpha synthesis.
Altogether, these results indicate that TETs are advantageous candidates
for the prophylaxis and treatment of septic shock in mice, having both
antimicrobial activity and the ability to inhibit endogenous TNF-alpha,
IL-1 alpha, and iNOS, hence, exerting, potent anti-inflammatory effects.
Copyright © 1997 by the American Society for Microbiology. All rights reserved.
Intraperitoneal injection of tetracyclines protects mice from lethal endotoxemia downregulating inducible nitric oxide synthase in various organs and cytokine and nitrate secretion in blood
Institute of General Pathology, University of Palermo, Italy.
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