- Browse by Subject
Browsing by Subject "Chronic granulomatous disease"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Hyperactivation of B cells from Immunodeficient Patients(Office of the Vice Chancellor for Research, 2013-04-05) McLetchie, Shawna K.; Deffit, Sarah N.; Gardiner, Gail J.Chronic granulomatous disease (CGD) is an inherited immunodeficiency associated with defects in NADPH oxidase, an enzyme that produces oxygen radicals necessary to kill bacterial and fungal pathogens. NADPH oxidase, made up of six subunits, is located in endosomal and plasma membranes of immune cells. Although best studied in macrophages and neutrophils, the oxidase is expressed in B cells where we have shown its link to adaptive immunity and antigen presentation. Here, NADPH oxidase function was disrupted by mutations or gene knockdown in human B cells, and the role of the oxidase in innate immunity specifically Toll-like receptor (TLR) signaling tested. TLR7 and 9, which recognize viral single-stranded RNA and unmethylated CpG DNA respectively, potentially share an endosomal compartment with the oxidase in B cells. In this project, B cells were stimulated for 24 hours with TLR7 and 9 ligands along with a costimulator PMA. TLR7 signaling was significantly enhanced in oxidase deficient B cell lines compared with their respective control cells as evidenced by increased IL-6 secretion detected by an ELISA. CGD patients are incapable of producing oxygen radicals rendering them immunodeficient in terms of pathogen infection. Yet these patients also develop many autoimmune disorders associated with hyperactivation of the immune system. Thus, our studies on TLR activation using CGD cell lines may explain in part the development of autoimmunity in individuals with CGD. Additional studies are underway to examine the regulation of TLR including receptor expression levels and the subcellular localization of the NADPH oxidase in these B cells from CGD patients. This work has not yet been published and was supported by NIH 3R01AI079065-03S1.Item Recurrent Serratia marcescens osteomyelitis eight years after a contaminated open fracture: a case report and review of the literature(AME, 2024) Mayhew, Jonathan A.; Christenson, John C.; Alali, Muayad; Pediatrics, School of MedicineBackground: Serratia marcescens (S. marcescens) is an unusual cause of osteomyelitis. Infection may develop following open trauma, intravenous drug abuse, or in the presence of hardware, but osteoarticular infections outside of this context are atypical in the absence of immunodeficiency. Rarely, a chronic indolent infection may develop after open trauma with disease recurrence years after the initial injury. Case description: We present the case of a 16-year-old male with extensive left lower extremity osteomyelitis secondary to S. marcescens eight years after an open fracture to this leg was complicated by an infection with the same organism. Suboptimal therapy of his initial infection may have contributed to persistent, latent disease before recurrence years later. Evaluation for immunodeficiency was negative and he responded well to ciprofloxacin antibiotic therapy. Conclusions: S. marcescens infection may complicate open fractures, and, if not adequately treated, a chronic, indolent infection may result, with disease recurrence years later. We stress the importance of adequate therapy for infectious complications following open fractures and discuss virulence factors of S. marcescens that may allow this organism to evade the immune system and survive subclinically within a host. The optimal therapy of S. marcescens osteomyelitis is not established and further studies are needed to best guide the therapeutic approach.Item Two CGD Families with a Hypomorphic Mutation in the Activation Domain of p67(phox)(OMICS Publishing Group, 2014-06-30) Roos, Dirk; van Buul, Jaap D.; Tool, Anton TJ; Matute, Juan D.; Marchal, Christophe M.; Hayee, Bu’Hussain; Köker, M. Yavuz; de Boer, Martin; van Leeuwen, Karin; Segal, Anthony W.; Pick, Edgar; Dinauer, Mary C.; Department of Pediatrics, IU School of MedicineSTUDY BACKGROUND: Chronic granulomatous Disease (CGD) is a rare immunodeficiency caused by a defect in the leukocyte NADPH oxidase. This enzyme generates superoxide, which is needed for the killing of bacteria and fungi by phagocytic leukocytes. Most CGD patients have mutations in CYBB, the X-linked gene that encodes gp91(phox), the catalytic subunit of the leukocyte NADPH oxidase. We report here three autosomal recessive CGD patients from two families with a homozygous mutation in NCF2, the gene that encodes p67(phox), the activator subunit of the NADPH oxidase. METHODS: Leukocyte NADPH oxidase activity, expression of oxidase components and gene sequences were measured with standard methods. The mutation found in the patients' NCF2 gene was expressed as Ala202Val-p67(phox) in K562 cells to measure its effect on NADPH oxidase activity. Translocation of the mutated p67(phox) from the cytosol of the patients' neutrophils to the plasma membrane was measured by confocal microscopy and by Western blotting after membrane purification. RESULTS: The exceptional feature of the A67 CGD patients reported here is that the p.Ala202Val mutation in the activation domain of p67(phox) was clearly hypomorphic: substantial expression of p67(phox) protein was noted and the NADPH oxidase activity in the neutrophils of the patients was 20-70% of normal, dependent on the stimulus used to activate the cells. The extent of Ala202Val-p67(phox) translocation to the plasma membrane during cell activation was also stimulus dependent. Ala202Val-p67(phox) in K562 cells mediated only about 3% of normal oxidase activity compared to cells transfected with the wild-type p67(phox). CONCLUSION: The mutation found in NCF2 is the cause of the decreased NADPH oxidase activity and the (mild) clinical problems of the patients. We propose that the p.Ala202Val mutation has changed the conformation of the activation domain of p67(phox), resulting in reduced activation of gp91(phox).