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Pyrrolidine dithiocarbamate attenuates endotoxin-induced acute lung injury
A B Nathens1, R Bitar, C Davreux
1Department of Surgery, University of Toronto, and the Toronto Hospital Research Institute, Ontario, Canada.
Abstract:
Lung injury in the acute respiratory distress syndrome (ARDS) is in part due to polymorphonuclear leukocyte (PMN)-mediated oxidative tissue damage. By means of nuclear factor-kappaB (NF-kappaB) activation, oxidants may also induce several genes implicated in the inflammatory response. The dithiocarbamates are antioxidants with potent inhibitory effects on NF-kappaB. We postulated that the pyrrolidine derivative pyrrolidine dithiocarbamate (PDTC) would attenuate lung injury following intratracheal challenge with endotoxin (lipopolysaccharide; LPS) through its effect as an antioxidant and inhibitor of gene activation. Rats were given PDTC (1 mmole/kg) by intraperitoneal injection, followed by intratracheal administration of LPS. The transpulmonary flux of [125I] albumin (permeability index; PI) was used as a measure of lung injury. Northern blot analysis of total lung RNA was performed to assess induction of tumor necrosis factor-alpha (TNF-alpha) and intercellular adhesion molecule-1 (ICAM-1) messenger RNA (mRNA) as markers of NF-kappaB activation. The effect of in vivo treatment with PDTC on LPS-induced NF-kappaB DNA binding activity in macrophage nuclear extracts was evaluated with the electrophoretic mobility shift assay (EMSA). PDTC administration attenuated LPS-induced increases in lung permeability (PI = 0.16 +/- 0.02 for LPS versus 0.06 +/- 0.01 for LPS + PDTC; P < 0.05). TNF-alpha levels and PMN counts in bronchoalveolar lavage fluid (BALF) were unaffected, as were whole-lung TNF-alpha and ICAM-1 mRNA expression. PDTC had no effect on NF-kappaB activation as evaluated with EMSA. PDTC reduced lung lipid peroxidation as assessed by levels of malondialdehyde, without reducing neutrophil oxidant production. We conclude that PDTC attenuates LPS-induced acute lung injury. This effect occurs independently of any effect on NF-kappaB. PDTC reduces oxidant-mediated cellular injury, as demonstrated by a reduction in the accumulation of malondialdehyde. Administration of PDTC may represent a novel approach to limiting neutrophil-mediated oxidant injury.
Insights
Pyrrolidine dithiocarbamate (PDTC) reduces acute lung injury caused by endotoxin. This antioxidant effect limits tissue damage independently of nuclear factor-kappaB (NF-kappaB) inhibition, offering a potential treatment for neutrophil-mediated lung injury.
Area of Science:
- Pulmonary Medicine
- Toxicology
- Molecular Biology
Background:
- Acute Respiratory Distress Syndrome (ARDS) involves polymorphonuclear leukocyte (PMN)-mediated oxidative damage.
- Oxidants can activate nuclear factor-kappaB (NF-kappaB), promoting inflammatory gene expression.
- Dithiocarbamates are antioxidants that inhibit NF-kappaB activation.
Purpose of the Study:
- To investigate if pyrrolidine dithiocarbamate (PDTC) attenuates endotoxin-induced lung injury in rats.
- To determine if PDTC's protective effects are mediated by antioxidant activity or NF-kappaB inhibition.
- To assess PDTC's impact on lung permeability, inflammatory markers, and oxidative stress.
Main Methods:
- Rats received PDTC intraperitoneally before intratracheal lipopolysaccharide (LPS) challenge.
- Lung injury was measured by transpulmonary [125I] albumin flux (permeability index).
- Gene expression (TNF-alpha, ICAM-1 mRNA) and NF-kappaB activation (EMSA) were analyzed. Lipid peroxidation was assessed by malondialdehyde levels.
Main Results:
- PDTC significantly attenuated LPS-induced increases in lung permeability.
- Tumor necrosis factor-alpha (TNF-alpha) levels, PMN counts, and inflammatory gene expression remained unaffected by PDTC.
- PDTC did not inhibit LPS-induced NF-kappaB activation but reduced lung lipid peroxidation.
Conclusions:
- PDTC attenuates acute lung injury induced by LPS through mechanisms independent of NF-kappaB inhibition.
- PDTC's protective effect is attributed to its antioxidant properties, reducing oxidant-mediated cellular injury.
- PDTC shows promise as a therapeutic agent for limiting neutrophil-mediated oxidant injury in the lungs.