Phenylmethimazole inhibits production of proinflammatory mediators and is protective in an experimental model of endotoxic shock*.

Abstract

BACKGROUND:

One form of sepsis, or endotoxic shock, is a hyperactivated systemic response caused by excessive expression of proinflammatory mediators, which results from Gram-negative bacterial lipopolysaccharide-stimulated Toll-like receptor-4 signaling. This lipopolysaccharide signaling is known to consist of a MyD88-dependent nuclear factor-κB-mediated pathway that results in production of proinflammatory mediators (tumor necrosis factor-α, interleukin-6, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, inducible nitric oxide synthase, cyclooxygenase-2) and a MyD88-independent interferon regulatory factor-mediated pathway that regulates production of Type 1 interferon-inducible proteins (interferon γ-induced protein-10, monocyte chemotactic protein-1). In prior studies, phenylmethimazole markedly decreased virally induced Toll-like receptor-3 expression and signaling and significantly suppressed murine colitis in an experimental model wherein lipopolysaccharide is known to play an important role.

OBJECTIVE:

In this study, we probed the hypothesis that phenylmethimazole inhibits lipopolysaccharide-mediated Toll-like receptor-4 signaling and is efficacious in attenuating inflammatory changes and improving survival in an in vivo murine model of endotoxic shock.

DESIGN:

Experimental animal model.

SETTING:

University laboratory.

SUBJECTS:

Male C57BL/6J mice weighing 18-22 g.

INTERVENTIONS:

Phenylmethimazole (1 mg/kg) was administered intraperitoneally to mice before a lethal lipopolysaccharide challenge (25 mg/kg). RAW264.7 mouse macrophage cells were pretreated with phenylmethimazole followed by lipopolysaccharide stimulation.

MEASUREMENTS AND MAIN RESULTS:

: Macroscopic observations revealed that phenylmethimazole was significantly protective in controlling clinical manifestations of endotoxic shock and death under conditions wherein flunixin of meglumine and prednisolone were marginally effective. A combination of enzyme-linked immunosorbent assay, Northern blot, reverse transcriptase-polymerase chain reaction, immunohistochemistry, and Western blot analyses showed that phenylmethimazole attenuated lipopolysaccharide-induced increases in production of proinflammatory cytokines (tumor necrosis factor-α, interleukin-6, interferon-γ), endothelial cell adhesion molecules (intercellular adhesion molecule-1, vascular cell adhesion molecule-1), inducible nitric oxide synthase and cyclooxygenase-2, interferon regulatory factor-1, interferon-inducible proteins (interferon γ-induced protein-10, monocyte chemotactic protein-1), and signal transducer and activator of transcription-1 phosphorylation in multiple tissues in mice. Consistent with these observations, electrophoretic mobility shift assay demonstrated that phenylmethimazole inhibited in vitro lipopolysaccharide-induced nuclear factor-κB and interferon regulatory factor-1 activation in RAW 264.7 mouse macrophages.

CONCLUSIONS:

Collectively, these results provide direct evidence that phenylmethimazole diminishes lipopolysaccharide-induced MyD88-dependent as well as MyD88-independent signaling pathways and is protective in an experimental model of endotoxic shock.

• Authors: Uruguaysito Benavides, Mariana Gonzalez-Murguiondo, Norikazu Harii, Christopher J Lewis, Anthony L Schwartz, Cesidio Giuliani, Giorgio Napolitano, Nilesh M Dagia, Ramiro Malgor, Kelly D McCall, Leonard D Kohn
• Journal: Critical care medicine (Crit Care Med) Vol. 40 Issue 3 Pg. 886-94 (Mar 2012) ISSN: 1530-0293 [Electronic] United States
• PMID: 22020240 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Cytokines
• Thiones
• phenyl methimazole
• Methimazole

Topics

• Animals
• Cytokines (biosynthesis, drug effects)
• Disease Models, Animal
• Inflammation (immunology)
• Male
• Methimazole (analogs & derivatives, therapeutic use)
• Mice
• Mice, Inbred C57BL
• Shock, Septic (immunology, metabolism, prevention & control)
• Thiones (therapeutic use)