Endotoxemia Induces IκBβ/NF-κB-Dependent Endothelin-1 Expression in Hepatic Macrophages.
Elevated serum concentrations of the vasoactive protein endothelin-1 (ET-1) occur in the setting of systemic inflammatory response syndrome and contribute to distal organ hypoperfusion and pulmonary hypertension. Thus, understanding the cellular source and transcriptional regulation of systemic inflammatory stress-induced ET-1 expression may reveal therapeutic targets. Using a murine model of LPS-induced septic shock, we demonstrate that the hepatic macrophage is the primary source of elevated circulating ET-1, rather than the endothelium as previously proposed. Using pharmacologic inhibitors, ET-1 promoter luciferase assays, and by silencing and overexpressing NF-κB inhibitory protein IκB expression, we demonstrate that LPS-induced ET-1 expression occurs via an NF-κB-dependent pathway. Finally, the specific role of the cRel/p65 inhibitory protein IκBβ was evaluated. Although cytoplasmic IκBβ inhibits activity of cRel-containing NF-κB dimers, nuclear IκBβ stabilizes NF-κB/DNA binding and enhances gene expression. Using targeted pharmacologic therapies to specifically prevent IκBβ/NF-κB signaling, as well as mice genetically modified to overexpress IκBβ, we show that nuclear IκBβ is both necessary and sufficient to drive LPS-induced ET-1 expression. Together, these results mechanistically link the innate immune response mediated by IκBβ/NF-κB to ET-1 expression and potentially reveal therapeutic targets for patients with Gram-negative septic shock.
Section of Neonatology, Department of Pediatrics, Children's Hospital Colorado, University of Colorado School of Medicine, Aurora, CO 80045;
Sarah
S
McKenna
Section of Neonatology, Department of Pediatrics, Children's Hospital Colorado, University of Colorado School of Medicine, Aurora, CO 80045;
Megan
M
Gossling
Section of Neonatology, Department of Pediatrics, Children's Hospital Colorado, University of Colorado School of Medicine, Aurora, CO 80045;
Alejandro
A
Bugarini
Section of Neonatology, Department of Pediatrics, Children's Hospital Colorado, University of Colorado School of Medicine, Aurora, CO 80045;
Elizabeth
E
Hill
Hepatology and Nutrition, Digestive Health Institute, Section of Gastroenterology, Department of Pediatrics, Children's Hospital Colorado, University of Colorado School of Medicine, Aurora, CO 80045; and.
Aimee L
AL
Anderson
Pediatric Airway Research Center, Section of Pulmonology, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045.
Raymond C
RC
Rancourt
Hepatology and Nutrition, Digestive Health Institute, Section of Gastroenterology, Department of Pediatrics, Children's Hospital Colorado, University of Colorado School of Medicine, Aurora, CO 80045; and.
Natarajan
N
Balasubramaniyan
Hepatology and Nutrition, Digestive Health Institute, Section of Gastroenterology, Department of Pediatrics, Children's Hospital Colorado, University of Colorado School of Medicine, Aurora, CO 80045; and.
Karim C
KC
El Kasmi
Section of Neonatology, Department of Pediatrics, Children's Hospital Colorado, University of Colorado School of Medicine, Aurora, CO 80045; clyde.wright@ucdenver.edu.
Clyde J
CJ
Wright
D000818:Animals; D002460:Cell Line; D019332:Endothelin-1 / Q000235:genetics / Q000276:immunology*; D019446:Endotoxemia / Q000235:genetics / Q000276:immunology* / Q000473:pathology; D005786:Gene Expression Regulation / Q000276:immunology*; D020672:I-kappa B Proteins / Q000235:genetics / Q000276:immunology*; D008099:Liver / Q000276:immunology* / Q000473:pathology; D008264:Macrophages / Q000276:immunology* / Q000473:pathology; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008822:Mice, Transgenic; D016328:NF-kappa B / Q000235:genetics / Q000276:immunology*; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*
D019332:Endothelin-1; C083487:I kappa B beta protein; D020672:I-kappa B Proteins; D016328:NF-kappa B