Molecular quality control machinery contributes to the leukocyte NADPH oxidase deficiency in chronic granulomatous disease

Abstract

Chronic granulomatous disease (CGD) is an inherited immunodeficiency disease caused by defects in leukocyte NADPH oxidase. Various inherited defects in one of the membrane-bound components of NADPH oxidase, gp91-phox, cause X-linked (X91) CGD. Analysis of three patients with X91 CGD revealed that different mechanisms of molecular quality control lead to the common phenotype of absence of mature membrane-bound NADPH oxidase complex in leukocytes. In the first patient, aberrant intron splicing created a premature stop codon. However, the mutant mRNA was degraded prematurely, which prevented the production of truncated protein. In the second patient, a frameshift mutation with the potential to generate a gp91-phox polypeptide, with an aberrant and elongated C-terminus, led to barely detectable levels of gp91-phox, even though the reported functional domains of the protein appeared unaffected. In the third patient, a point mutation created a single amino acid change in the predicted FAD-binding site of gp91-phox. Although gp91-phox was detectable with Western blotting, no cytochrome b(558) was expressed on the cell surface. These analyses showed that molecular quality control machinery plays an important role in the pathogenesis of CGD, not only in the X910 but also in the X91- form of this X-linked disease.

Superoxide activates very late antigen‐4 on an eosinophil cell line and increases cellular binding to vascular cell adhesion molecule‐1

“…However, when we used neutrophils from a CGD patient along with normal controls as the source of superoxide in our experiments (Fig. 6, fifth and sixth panels), the suppressive activity of NO was significant in both conditions even though almost no ROS was produced by the CGD neutrophils (data not shown and [20]). These results suggest that NO might suppress eosinophil binding to VCAM-1 in a mechanism different from that of superoxide-mediated enhancement of cell binding.…”

“…Children deficient in components of NADPH oxidase are defective in superoxide generation and hence suffer from recurrent and serious infections. This condition is termed CGD [20][21][22]. Many investigations have shown that ROS produced by leukocyte NADPH oxidase modulate the expression of adhesion molecules involved in leukocyte trafficking [13,14].…”

“…producing enzyme, NADPH oxidase [20], or neutrophils from normal controls were used for co-adhesion experiments. While neutrophils from normal controls increased HL-60 clone 15 binding to VCAM-1, neutrophils from a CGD patient had no effects (Fig.…”

“…Ten milliliters of heparinized peripheral blood was obtained from non-allergic, healthy donors or a patient with CGD [20]. Neutrophils were isolated by dextran sedimentation for 30 min and loaded onto Ficoll-Hypaque (Amersham Biosciences, GB) and centrifuged at 2,000 rpm for 15 min.…”

Ligand binding of leukocyte integrin very late antigen‐4 involves exposure of sulfhydryl groups and is subject to redox modulation

“…Meanwhile, the activation of leukocytes usually leads to activation of NADPH oxidase and production of reactive oxygen species (ROS), which are crucial for effective immune defense [5][6][7]. Our previous studies showed that ROS produced by activated granulocytes affect eosinophil binding to VCAM-1 [8].…”