Specific modulation of calmodulin activity induces a dramatic production of superoxide by alveolar macrophages.
Airway inflammation is a characteristic feature in airway diseases such as asthma and chronic obstructive pulmonary disease. Oxidative stress, caused by the excessive production of reactive oxygen species by inflammatory cells like macrophages, eosinophils and neutrophils, is thought to be important in the complex pathogenesis of such airway diseases. The calcium-sensing regulatory protein calmodulin (CaM) binds and regulates different target enzymes and proteins, including calcium channels. In the present study, we investigated whether CaM, via the modulation of calcium channel function, influences [Ca(2+)](i) in pulmonary inflammatory cells, and consequently, modulates the production of reactive oxygen species by these cells. This was tested with a peptide termed calcium-like peptide 2 (CALP2), which was previously shown to regulate such channels. Specifically, radical production by purified broncho-alveolar lavage cells from guinea-pigs in response to CALP2 was measured. CALP2 was a strong activator of alveolar macrophages. In contrast, CALP2 was only a mild activator of neutrophils and did not induce radical production by eosinophils. The CALP2-induced radical production was mainly intracellular, and was completely blocked by the NADPH-oxidase inhibitor DPI, the superoxide inhibitor SOD and the CaM antagonist W7. Furthermore, the calcium channel blocker lanthanum partly inhibited the cellular activation by CALP2. We conclude that alveolar macrophages, but not neutrophils or eosinophils, can produce extremely high amounts of reactive oxygen species when stimulated via the calcium/CaM pathway. These results may contribute to new therapeutic strategies against oxidative stress in airway diseases.
Broeke
Robert Ten
RT
Department of Pharmacology and Pathophysiology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands.
Leusink-Muis
Thea
T
Hilberdink
Rogier
R
Van Ark
Ingrid
I
van den Worm
Edwin
E
Villain
Matteo
M
De Clerck
Fred
F
Blalock
J Edwin
JE
Nijkamp
Frans P
FP
Folkerts
Gert
G
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry / Q000166:cytology; D002118:Calcium / Q000378:metabolism; D002120:Calcium Channel Agonists / Q000378:metabolism; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006168:Guinea Pigs; D036341:Intercellular Signaling Peptides and Proteins; D016676:Macrophages, Alveolar / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009861:Onium Compounds / Q000494:pharmacology; D010455:Peptides / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013449:Sulfonamides / Q000494:pharmacology; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism*
C420971:CALP2 protein, synthetic; D002120:Calcium Channel Agonists; D002147:Calmodulin; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D036341:Intercellular Signaling Peptides and Proteins; D009861:Onium Compounds; D010455:Peptides; D013449:Sulfonamides; D013481:Superoxides; C017967:W 7; C007517:diphenyleneiodonium; D013482:Superoxide Dismutase; D002118:Calcium