Calcium and calmodulin regulate lipopolysaccharide-induced alveolar macrophage production of tumor necrosis factor and procoagulant activity

C. J. Lo, I. Garcia, H. G. Cryer and R. V. Maier
Department of Surgery, University of California, Los Angeles, USA.

BACKGROUND: Alterations in macrophage (M phi) function are responsible, in part, for adult respiratory distress syndrome and multiple organ failure developing in patients with sepsis. Elucidation and control of these M phi mechanisms during sepsis are crucial to our understanding of this disease and, ultimately, to improving survival of these patients. OBJECTIVE: To investigate the involvement of calcium flux in endotoxin-induced alveolar M phi production of tumor necrosis factor (TNF) and procoagulant (PC) activity. DESIGN: Rabbit alveolar M phi obtained by bronchoalveolar lavage were exposed to endotoxin in the form of lipopolysaccharide (LPS) extracted from Escherichia coli 0111:B4 in the presence of different specific calcium agonists and antagonists. The TNF expression was measured in the supernatant by L929 bioassays. The PC activity was determined in cell lysates by a one-step coagulation assay. RESULTS: Macrophages activated by LPS produce enormous levels of TNF and PC. Either W7 (20 mumol/L), a calmodulin antagonist, or TMB-8 (50 mumol/L), which prevents calcium release from the endoplasmic reticulum, inhibited production of both TNF and PC activity. Verapamil (50 mumol/L) alone or combined with TMB-8 significantly inhibited both TNF and PC production by LPS-stimulated M phi. Elevating intracellular calcium ([Ca2+]i), using the calcium ionophore, A23187, or thapsigargin alone, did not induce M phi production of TNF but significantly augmented LPS-stimulated TNF production. CONCLUSION: Our results indicate that increased intracellular calcium causing signal transduction activation through the calmodulin pathway is a necessary, but insufficient, component of the LPS signaling in M phi.

THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES

Diltiazem suppresses collagen synthesis and IL-1{beta}-induced TGF-{beta}1 production on human peritoneal mesothelial cells
Fang et al.
Nephrol Dial Transplant 2006;21:1340-1347.
ABSTRACT | FULL TEXT  

Distinct Role of Calmodulin and Calmodulin-dependent Protein Kinase-II in Lipopolysaccharide and Tumor Necrosis Factor-{alpha}-mediated Suppression of Apoptosis and Antiapoptotic c-IAP2 Gene Expression in Human Monocytic Cells
Mishra et al.
J. Biol. Chem. 2005;280:37536-37546.
ABSTRACT | FULL TEXT  

Calcium and ROS-mediated activation of transcription factors and TNF-{alpha} cytokine gene expression in macrophages exposed to ultrafine particles
Brown et al.
Am. J. Physiol. Lung Cell. Mol. Physiol. 2004;286:L344-L353.
ABSTRACT | FULL TEXT  

Norepinephrine-induced hepatocellular dysfunction in early sepsis is mediated by activation of alpha 2-adrenoceptors
Yang et al.
Am. J. Physiol. Gastrointest. Liver Physiol. 2001;281:G1014-G1021.
ABSTRACT | FULL TEXT  

Involvement of protein kinases in the potentiation of lipopolysaccharide-induced inflammatory mediator formation by thapsigargin in peritoneal macrophages
Chen et al.
J. Leukoc. Biol. 2001;69:280-288.
ABSTRACT | FULL TEXT  

Signaling Mechanisms of Altered Cellular Responses in Trauma, Burn, and Sepsis: Role of Ca2+
Sayeed
Arch Surg 2000;135:1432-1442.
ABSTRACT | FULL TEXT  

Release of Calcium from Inositol 1,4,5-Trisphosphate Receptor-Regulated Stores by HIV-1 Tat Regulates TNF-{alpha} Production in Human Macrophages
Mayne et al.
J. Immunol. 2000;164:6538-6542.
ABSTRACT | FULL TEXT  

NF-{kappa}B Modulates TNF-{alpha} Production by Alveolar Macrophages in Asymptomatic HIV-Seropositive Individuals
Mathys et al.
J. Immunol. 2000;164:1588-1594.
ABSTRACT | FULL TEXT