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Chronic granulomatous disease: more than the lack of superoxide?
1Department of Physiology, Semmelweis University, Budapest, Hungary. mgeiszt@nih.gov
Insights
Chronic granulomatous disease (CGD) impairs phagocytic cells' ability to kill pathogens due to defective NADPH oxidase. This review explores gp91phox's proton channel function and its impact on ion balance in CGD neutrophils.
Area of Science:
- Immunology
- Cell Biology
- Electrophysiology
Background:
- Chronic granulomatous disease (CGD) is an inherited immune disorder causing severe, recurrent infections.
- CGD patients exhibit impaired superoxide anion production in phagocytes, hindering pathogen killing.
- Electrophysiological alterations in CGD granulocytes are implicated in disease pathogenesis.
Purpose of the Study:
- To review the proton channel function of gp91phox, a key component of NADPH oxidase.
- To discuss the electrogenic activity of the NADPH oxidase complex and its effect on ion transport.
- To propose a hypothesis on altered intracellular ion composition in CGD neutrophils during phagocytosis.
Main Methods:
- Literature review of existing research on CGD, NADPH oxidase, and ion transport.
- Analysis of electrophysiological data concerning CGD granulocytes.
- Hypothesis formulation based on current understanding of NADPH oxidase function.
Main Results:
- gp91phox exhibits proton channel activity, influencing transmembrane ion flux.
- The active NADPH oxidase complex has electrogenic properties affecting ion trafficking.
- Absence of functional NADPH oxidase may lead to altered intracellular and intraphagosomal ion concentrations.
Conclusions:
- The proton channel function of gp91phox and the electrogenic nature of NADPH oxidase are critical aspects of CGD pathogenesis.
- Altered ion homeostasis in CGD neutrophils could significantly impact phagocytosis and host defense.
- Further research into ion channel activity and its role in CGD is warranted.
Abstract:
Chronic granulomatous disease (CGD) is an inherited disease characterized by severe and recurrent bacterial and fungal infections manifested in most cases in early childhood. Phagocytic cells of CGD patients are unable to produce superoxide anions, and their efficiency in bacterial killing is significantly impaired. Recent work has shown alterations in the electrophysiological properties of CGD granulocytes, which might contribute to the pathogenesis of the disease. The new aspects that we discuss in this review concern the proton channel function of gp91phox (the electron-transporting subunit of the NADPH oxidase) and the electrogenic activity of the active enzyme complex, which can affect the transmembrane trafficking of several ions. Based on the reviewed data, we also propose a hypothesis that the absence of a functional NADPH oxidase in CGD neutrophils could result in altered ion compositions within intracellular and intraphagosomal spaces during the process of phagocytosis.