Clinical Studies Of Abnormal Host Defense

National Institute Of Allergy And Infectious Diseases

Investigators

Linked publications & trials

Abstract

(1) Chronic granulomatous disease (CGD) is a primary immunodeficiency caused by mutations in the multicomponent NADPH oxidase (phagocyte oxidase, NOX2) complex. During FY22, through collaboration with the Neutrophil Monitoring Laboratory (NML) managed by Douglas Kuhns, PhD (Leidos, Inc.), we provided molecular diagnoses using immunodetection of components of the NADPH oxidase for 17 new patients with CGD. Together with previous patients, this brings the CGD cohort available for study at the NIH CC to 552 patients and 348 carriers from 492 families. (2) Our group continues its clinical studies of the emerging Gram-negative CGD pathogen, Granulibacter bethesdensis. We continue to monitor seropositivity in culture-confirmed patients and patients suspected of having a Granulibacter infection to evaluate our hypothesis that this organism can establish persistent, clinically silent infections. During FY22 we performed serologic studies on 4 suspected cases at the NIH Clinical Center. Although rare, reported Granulibacter infections in CGD patients have a case fatality rate of 30% suggesting that more work is required to improve diagnosis and treatment of this pathogen. This year, we have begun whole genome sequencing of an additional 2 clinical isolates. (3) Based on the initial results of our clinical study (10-I-0029), we have been collaborating with investigators at the National Center for Advancing Translational Sciences (NCATS) to identify chemical inhibitors of NOX2. Using a cell line developed by Tom Leto in the LCIM, we developed a lab scale-screening assay for NOX2 activity that then optimized by NCATS for high throughput, robotic screening for inhibitors of NOX2. To date, we have evaluated over 70,000 compounds in primary and secondary screens and are working on variants of lead candidates for further study. Given the high rate of false-positive compounds in the first-generation primary screen, we are actively developing several alternative assays for NOX2 that do not rely on indirect measurements of enzyme activity in intact cells but rather focus either on subunit interactions (binding) that are known to regulate assembly of the active enzyme complex or a highly purified enzyme complex with artificial activators that function as a molecularly defined assay instead of a whole cell. During FY22, we developed assays for other NOX family members (e.g., NOX1, NOX3, NOX4, NOX5) in order to test specificity of these compounds and are working towards developing assays of DUOXes as well. We have also performed studies of wild-type mice and mouse strains that are genetically deficient in various NOX enzymes (NOX1, NOX2, NOX4) to evaluate their contributions to pathogenesis in a model of traumatic brain injury in collaboration with Dr. Dorian McGavern (NINDS). This model has also been used to evaluate lead NOX2 inhibitors and further ongoing experiments to definitively prove the involvement of NOX2 in this process are underway.