Specific modulation of calmodulin activity induces a dramatic production of superoxide by alveolar macrophages

Abstract

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 þ ] 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.

Differential Modulation of 7-Ketocholesterol Toxicity Against PC12 Cells by Calmodulin Antagonists and Ca2+ Channel Blockers

“…In the present study, no effect of nicardipine and BAPTA-AM and inhibitory effect of calmodulin antagonists suggest that the 7-ketocholesterol-induced oxidative stress may be mediated by calmodulin rather than changes in intracellular Ca 2+ levels. It has been shown that alveolar macrophages stimulated via Ca 2+ /calmodulin pathway produce high amounts of ROS [47]. In relation to this result, the current data indicates that calmodulin antagonists seem to prevent the 7-ketocholesterol-induced oxidative stress through the inhibitory action against the ROS formation process mediated by Ca 2+ /calmodulin.…”

Effect of Priming in Subpopulations of Peripheral Neutrophils From Patients with Chronic Periodontitis

“…The calcium sensing regulatory protein calmodulin binds and regulates different target enzymes and proteins, including calcium channels, which modulate ROS in inflammatory cells 29 . To inhibit generation of the superoxide anion, the calmodulin antagonist W13 was used, and the effect was an almost total inhibition of intracellular ROS as measured by fluorescent rhodamine 123.…”

Increases in Calmodulin Abundance and Stabilization of Activated Inducible Nitric Oxide Synthase Mediate Bacterial Killing in RAW 264.7 Macrophages

“…Thus, observed age-dependent declines in CaM function and abundance may relate to observed declines in immune function ( 2 , − . However, the downregulation of CaM function through the addition of inhibitors and binding peptides can also activate macrophages and block bacterial infections ( , ), suggesting a multifactorial role for CaM in mediating macrophage activation and bacterial killing.…”