Andrés Augusto Arias

A new genetic subgroup of chronic granulomatous disease with autosomal recessive mutations in p40phox and selective defects in neutrophil NADPH oxidase activity

Chronic granulomatous disease (CGD), an immunodeficiency with recurrent pyogenic infections and granulomatous inflammation, results from loss of phagocyte superoxide production by recessive mutations in any 1 of 4 genes encoding subunits of the phagocyte NADPH oxidase. These include gp91(phox) and p22(phox), which form the membrane-integrated flavocytochrome b, and cytosolic subunits p47(phox) and p67(phox). A fifth subunit, p40(phox), plays an important role in phagocytosis-induced superoxide production via a phox homology (PX) domain that binds to phosphatidylinositol 3-phosphate (PtdIns(3)P). We report the first case of autosomal recessive mutations in NCF4, the gene encoding p40(phox), in a boy who presented with granulomatous colitis. His neutrophils showed a substantial defect in intracellular superoxide production during phagocytosis, whereas extracellular release of superoxide elicited by phorbol ester or formyl-methionyl-leucyl-phenylalanine (fMLF) was unaffected. Genetic analysis of NCF4 showed compound heterozygosity for a frameshift mutation with premature stop codon and a missense mutation predicting a R105Q substitution in the PX domain. Parents and a sibling were healthy heterozygous carriers. p40(phox)R105Q lacked binding to PtdIns(3)P and failed to reconstitute phagocytosis-induced oxidase activity in p40(phox)-deficient granulocytes, with premature loss of p40(phox)R105Q from phagosomes. Thus, p40(phox) binding to PtdIns(3)P is essential for phagocytosis-induced oxidant production in human neutrophils and its absence can be associated with disease.

Cutting Edge: NADPH Oxidase Modulates MHC Class II Antigen Presentation by B Cells

Phagocyte NADPH oxidase plays a key role in pathogen clearance via reactive oxygen species (ROS) production. Defects in oxidase function result in chronic granulomatous disease with hallmark recurrent microbial infections and inflammation. The oxidase’s role in the adaptive immune response is not well understood. Class II presentation of cytoplasmic and exogenous Ag to CD4+ T cells was impaired in human B cells with reduced oxidase p40phox subunit expression. Naturally arising mutations, which compromise p40phox function in a chronic granulomatous disease patient, also perturbed class II Ag presentation and intracellular ROS production. Reconstitution of patient B cells with a wild-type, but not a mutant, p40phox allele restored exogenous Ag presentation and intracellular ROS generation. Remarkably, class II presentation of epitopes from membrane Ag was robust in p40phox-deficient B cells. These studies reveal a role for NADPH oxidase and p40phox in skewing epitope selection and T cell recognition of self Ag.

Edelfosine Induces an Apoptotic Process in Leishmania infantum That Is Regulated by the Ectopic Expression of Bcl-XL and Hrk

ABSTRACT The alkyl-lysophospholipids edelfosine and miltefosine induce apoptosis in Leishmania infantum promastigotes. The finding that edelfosine-induced cell death can be regulated by the ectopic expression of the antiapoptotic and proapoptotic members of the Bcl-2 family of proteins Bcl-XL and Hrk suggests that this process is similar to apoptosis in eukaryotic cells.

Activation of neutrophil respiratory burst by fungal particles requires phosphatidylinositol 3-phosphate binding to p40(phox) in humans but not in mice.

To the editor: Null mutations in leukocyte NADPH oxidase subunits gp91 phox , p22 phox , p67 phox and p47 phox are associated with a loss of superoxide-generating enzyme activity on both plasma and phagosomal membranes in chronic granulomatous disease (CGD) patients and CGD mouse models. In

The human CIB1–EVER1–EVER2 complex governs keratinocyte-intrinsic immunity to β-papillomaviruses

Patients with epidermodysplasia verruciformis (EV) and biallelic null mutations of TMC6 (encoding EVER1) or TMC8 (EVER2) are selectively prone to disseminated skin lesions due to keratinocyte-tropic human &bgr;-papillomaviruses (&bgr;-HPVs), which lack E5 and E8. We describe EV patients homozygous for null mutations of the CIB1 gene encoding calcium- and integrin-binding protein-1 (CIB1). CIB1 is strongly expressed in the skin and cultured keratinocytes of controls but not in those of patients. CIB1 forms a complex with EVER1 and EVER2, and CIB1 proteins are not expressed in EVER1- or EVER2-deficient cells. The known functions of EVER1 and EVER2 in human keratinocytes are not dependent on CIB1, and CIB1 deficiency does not impair keratinocyte adhesion or migration. In keratinocytes, the CIB1 protein interacts with the HPV E5 and E8 proteins encoded by &agr;-HPV16 and &ggr;-HPV4, respectively, suggesting that this protein acts as a restriction factor against HPVs. Collectively, these findings suggest that the disruption of CIB1–EVER1–EVER2-dependent keratinocyte-intrinsic immunity underlies the selective susceptibility to &bgr;-HPVs of EV patients.

Early-Onset Invasive Infection Due to Corynespora cassiicola Associated with Compound Heterozygous CARD9 Mutations in a Colombian Patient

PurposeCARD9 deficiency is an inborn error of immunity that predisposes otherwise healthy humans to mucocutaneous and invasive fungal infections, mostly caused by Candida, but also by dermatophytes, Aspergillus, and other fungi. Phaeohyphomycosis are an emerging group of fungal infections caused by dematiaceous fungi (phaeohyphomycetes) and are being increasingly identified in patients with CARD9 deficiency. The Corynespora genus belongs to phaeohyphomycetes and only one adult patient with CARD9 deficiency has been reported to suffer from invasive disease caused by C. cassiicola. We identified a Colombian child with an early-onset, deep, and destructive mucocutaneous infection due to C. cassiicola and we searched for mutations in CARD9.MethodsWe reviewed the medical records and immunological findings in the patient. Microbiologic tests and biopsies were performed. Whole-exome sequencing (WES) was made and Sanger sequencing was used to confirm the CARD9 mutations in the patient and her family. Finally, CARD9 protein expression was evaluated in peripheral blood mononuclear cells (PBMC) by western blotting.ResultsThe patient was affected by a large, indurated, foul-smelling, and verrucous ulcerated lesion on the left side of the face with extensive necrosis and crusting, due to a C. cassiicola infectious disease. WES led to the identification of compound heterozygous mutations in the patient consisting of the previously reported p.Q289* nonsense (c.865C > T, exon 6) mutation, and a novel deletion (c.23_29del; p.Asp8Alafs10*) leading to a frameshift and a premature stop codon in exon 2. CARD9 protein expression was absent in peripheral blood mononuclear cells from the patient.ConclusionWe describe here compound heterozygous loss-of-expression mutations in CARD9 leading to severe deep and destructive mucocutaneous phaeohyphomycosis due to C. cassiicola in a Colombian child.

Enfermedad por almacenamiento de glucógeno de tipo III en pacientes colombianos: caracterización clínica y molecular

INTRODUCTION Type III glycogen storage disease (GSD III) is an autosomal recessive disorder in which a mutation in the AGL gene causes deficiency of the glycogen debranching enzyme. The disease is characterized by fasting hypoglycemia, hepatomegaly and progressive myopathy. Molecular analyses of AGL have indicated heterogeneity depending on ethnic groups. The full spectrum of AGL mutations in Colombia remains unclear. OBJECTIVE To describe the clinical and molecular characteristics of ten Colombian patients diagnosed with GSD III. MATERIALS AND METHODS We recruited ten Colombian children with a clinical and biochemical diagnosis of GSD III to undergo genetic testing. The full coding exons and the relevant exon-intron boundaries of the AGL underwent Sanger sequencing to identify mutation. RESULTS All patients had the classic phenotype of the GSD III. Genetic analysis revealed a mutation p.Arg910X in two patients. One patient had the mutation p.Glu1072AspfsX36, and one case showed a compound heterozygosity with p.Arg910X and p.Glu1072AspfsX36 mutations. We also detected the deletion of AGL gene 3, 4, 5, and 6 exons in three patients. The in silico studies predicted that these defects are pathogenic. No mutations were detected in the amplified regions in three patients. CONCLUSION We found mutations and deletions that explain the clinical phenotype of GSD III patients. This is the first report with a description of the clinical phenotype and the spectrum of AGL mutations in Colombian patients. This is important to provide appropriate prognosis and genetic counseling to the patient and their relatives.

Molecular and clinical characterization of Colombian patients suffering from type III glycogen storage disease

INTRODUCTION Type III glycogen storage disease (GSD III) is an autosomal recessive disorder in which a mutation in the AGL gene causes deficiency of the glycogen debranching enzyme. The disease is characterized by fasting hypoglycemia, hepatomegaly and progressive myopathy. Molecular analyses of AGL have indicated heterogeneity depending on ethnic groups. The full spectrum of AGL mutations in Colombia remains unclear. OBJECTIVE To describe the clinical and molecular characteristics of ten Colombian patients diagnosed with GSD III. MATERIALS AND METHODS We recruited ten Colombian children with a clinical and biochemical diagnosis of GSD III to undergo genetic testing. The full coding exons and the relevant exon-intron boundaries of the AGL underwent Sanger sequencing to identify mutation. RESULTS All patients had the classic phenotype of the GSD III. Genetic analysis revealed a mutation p.Arg910X in two patients. One patient had the mutation p.Glu1072AspfsX36, and one case showed a compound heterozygosity with p.Arg910X and p.Glu1072AspfsX36 mutations. We also detected the deletion of AGL gene 3, 4, 5, and 6 exons in three patients. The in silico studies predicted that these defects are pathogenic. No mutations were detected in the amplified regions in three patients. CONCLUSION We found mutations and deletions that explain the clinical phenotype of GSD III patients. This is the first report with a description of the clinical phenotype and the spectrum of AGL mutations in Colombian patients. This is important to provide appropriate prognosis and genetic counseling to the patient and their relatives.