Effects of radiodetoxified endotoxin on nitric oxide production in J774 macrophages and in endotoxin shock

E. Gilad, B. Zingarelli, M. O'Connor, A. L. Salzman, L. Bertok, Csaba Szabo

Research output: Contribution to journalArticle

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Abstract

Radiodetoxified lipopolysaccharide (RD-LPS) is a 60Co-gamma-irradiated LPS with a modified structure, which decreases its toxic effects. To obtain a better understanding of the mechanism of the reduced toxicity of RD-LPS, here we studied the effect of RD-LPS on the regulation of nitric oxide (NO) production in vitro and in vivo. In control cells, stimulation by native LPS (10 μg/ml) induced the expression of the inducible NO synthase (iNOS) and production of NO, as measured by increase in the concentration of nitrite, breakdown product of NO. Pre-exposure of the cells for 24 h to a subthreshold concentration of RD-LPS (10 ng/ml) induced a complete desensitization to the LPS-induced NO production in comparison to control cells (P < 0.01). On the contrary, pre-exposure of the cells with native LPS (10 ng/ml) did not reduce LPS-induced NO synthesis. RD-LPS induced a smaller production of tumor necrosis factor (TNF) than native LPS, but did not induce a desensitization against subsequent LPS-induced TNF synthesis. In in vivo studies, pretreatment of rats with repeated doses of sublethal RD-LPS (1 mg/kg/day i.p. for 4 days) inhibited increase of plasma nitrate/nitrite levels, NO production in peritoneal macrophages ex vivo and induction of lung iNOS activity, in response to a high-dose LPS challenge (15 mg/kg i.p.) given at the fifth day. Pretreatment with repeated sublethal doses of the native LPS (1 mg/kg/day i.p.) did not affect NO production in rats subjected to endotoxic shock. The results demonstrate that RD-LPS induces tolerance to the stimulatory effect of LPS on NO synthesis. Suppression of iNOS induction was only observed with RD-LPS, but not with native LPS in the models used herein. It remains to be further investigated whether suppression of iNOS induction by RD-LPS contributes to the protective effects of this compound in shock and inflammation.

Original languageEnglish (US)
Pages (from-to)513-519
Number of pages7
JournalJournal of Endotoxin Research
Volume3
Issue number6
StatePublished - 1996
Externally publishedYes

Fingerprint

Macrophages
Endotoxins
Lipopolysaccharides
Shock
Nitric Oxide
Nitric Oxide Synthase
Nitrites
Rats
Tumor Necrosis Factor-alpha
Poisons
Peritoneal Macrophages
Nitric Oxide Synthase Type II
Septic Shock
Nitrates
Toxicity
Inflammation
Plasmas
Lung

ASJC Scopus subject areas

  • Immunology
  • Microbiology
  • Toxicology

Cite this

Effects of radiodetoxified endotoxin on nitric oxide production in J774 macrophages and in endotoxin shock. / Gilad, E.; Zingarelli, B.; O'Connor, M.; Salzman, A. L.; Bertok, L.; Szabo, Csaba.

In: Journal of Endotoxin Research, Vol. 3, No. 6, 1996, p. 513-519.

Research output: Contribution to journalArticle

Gilad, E, Zingarelli, B, O'Connor, M, Salzman, AL, Bertok, L & Szabo, C 1996, 'Effects of radiodetoxified endotoxin on nitric oxide production in J774 macrophages and in endotoxin shock', Journal of Endotoxin Research, vol. 3, no. 6, pp. 513-519.
Gilad, E. ; Zingarelli, B. ; O'Connor, M. ; Salzman, A. L. ; Bertok, L. ; Szabo, Csaba. / Effects of radiodetoxified endotoxin on nitric oxide production in J774 macrophages and in endotoxin shock. In: Journal of Endotoxin Research. 1996 ; Vol. 3, No. 6. pp. 513-519.
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