Anti-GM-CSF Neutralizing Autoantibodies in Colombian Patients with Disseminated Cryptococcosis.

BACKGROUND: Cryptococcosis is a potentially life-threatening fungal disease caused by encapsulated yeasts of the genus Cryptococcus, mostly C. neoformans or C. gattii. Cryptococcal meningitis is the most frequent clinical manifestation in humans. Neutralizing autoantibodies (auto-Abs) against granulocyte-macrophage colony-stimulating factor (GM-CSF) have recently been discovered in otherwise healthy adult patients with cryptococcal meningitis, mostly caused by C. gattii. We hypothesized that three Colombian patients with cryptococcal meningitis caused by C. neoformans in two of them would carry high plasma levels of neutralizing auto-Abs against GM-CSF. METHODS: We reviewed medical and laboratory records, performed immunological evaluations, and tested for anti-cytokine auto-Abs three previously healthy HIV-negative adults with disseminated cryptococcosis. RESULTS: Peripheral blood leukocyte subset levels and serum immunoglobulin concentrations were within the normal ranges. We detected high levels of neutralizing auto-Abs against GM-CSF in the plasma of all three patients. CONCLUSIONS: We report three Colombian patients with disseminated cryptococcosis associated with neutralizing auto-Abs against GM-CSF. Further studies should evaluate the genetic contribution to anti-GM-CSF autoantibody production and the role of the GM-CSF signaling pathway in the immune response to Cryptococcus spp.

Germline CYBB mutations that selectively affect macrophages in kindreds with X-linked predisposition to tuberculous mycobacterial disease.

Germline mutations in CYBB, the human gene encoding the gp91(phox) subunit of the phagocyte NADPH oxidase, impair the respiratory burst of all types of phagocytes and result in X-linked chronic granulomatous disease (CGD). We report here two kindreds in which otherwise healthy male adults developed X-linked recessive Mendelian susceptibility to mycobacterial disease (MSMD) syndromes. These patients had previously unknown mutations in CYBB that resulted in an impaired respiratory burst in monocyte-derived macrophages but not in monocytes or granulocytes. The macrophage-specific functional consequences of the germline mutation resulted from cell-specific impairment in the assembly of the NADPH oxidase. This 'experiment of nature' indicates that CYBB is associated with MSMD and demonstrates that the respiratory burst in human macrophages is a crucial mechanism for protective immunity to tuberculous mycobacteria.

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 p40(phox) subunit expression. Naturally arising mutations, which compromise p40(phox) 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, p40(phox) allele restored exogenous Ag presentation and intracellular ROS generation. Remarkably, class II presentation of epitopes from membrane Ag was robust in p40(phox)-deficient B cells. These studies reveal a role for NADPH oxidase and p40(phox) in skewing epitope selection and T cell recognition of self Ag.

Autoantibodies neutralizing GM-CSF in HIV-negative Colombian patients infected with Cryptococcus gattii and C. neoformans.

Background: Cryptococcosis is a life-threatening disease caused by Cryptococcus neoformans or C. gattii. Autoantibodies (auto-Abs) neutralizing granulocyte-macrophage colony-stimulating factor (GM-CSF) in otherwise healthy adults with cryptococcal meningitis have been described since 2013. We searched for neutralizing auto-Abs in sera from Colombian patients with non-HIV related cryptococcosis in a retrospective national cohort collected from 1997 to 2016. Methods: We reviewed clinical and laboratory records and assessed the presence of neutralizing auto-Abs in 30 HIV (-) adults presenting cryptococcosis (13 by C. gattii, and 17 by C. neoformans). Results: We detected auto-Abs neutralizing GM-CSF in the plasma of 9 out of 13 (69%) patients infected with C. gattii and 1 out of 17 (6%) patients with C. neoformans. Conclusions: We report ten Colombian patients with cryptococcosis due to auto-Abs neutralizing GM-CSF. Nine of the ten patients were infected with C. gattii, and only one with C. neoformans.

Inborn errors of OAS-RNase L in SARS-CoV-2-related multisystem inflammatory syndrome in children.

Multisystem inflammatory syndrome in children (MIS-C) is a rare and severe condition that follows benign COVID-19. We report autosomal recessive deficiencies of OAS1, OAS2, or RNASEL in five unrelated children with MIS-C. The cytosolic double-stranded RNA (dsRNA)-sensing OAS1 and OAS2 generate 2'-5'-linked oligoadenylates (2-5A) that activate the single-stranded RNA-degrading ribonuclease L (RNase L). Monocytic cell lines and primary myeloid cells with OAS1, OAS2, or RNase L deficiencies produce excessive amounts of inflammatory cytokines upon dsRNA or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) stimulation. Exogenous 2-5A suppresses cytokine production in OAS1-deficient but not RNase L-deficient cells. Cytokine production in RNase L-deficient cells is impaired by MDA5 or RIG-I deficiency and abolished by mitochondrial antiviral-signaling protein (MAVS) deficiency. Recessive OAS-RNase L deficiencies in these patients unleash the production of SARS-CoV-2-triggered, MAVS-mediated inflammatory cytokines by mononuclear phagocytes, thereby underlying MIS-C.

A new genetic subgroup of chronic granulomatous disease with autosomal recessive mutations in p40 phox 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.

Cardiometabolic risk factors in preschool children with abdominal obesity from Medellín, Colombia.

Background Abdominal obesity (AO) is linked to inflammation and insulin resistance (IR). However, there is limited information on whether preschoolers with AO present these risk factors. We evaluated the association between AO and cardiovascular risk factors in preschoolers. Methods We enrolled 232 children (2-5 years), of whom 50% had AO. Serum total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-c), high-density lipoprotein-cholesterol (HDL-c), triglycerides (TG), apolipoprotein B (Apo-B) and apolipoprotein A-1 (Apo-A1), glucose, insulin, high-sensitivity C-reactive protein (hs-CRP), tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, IL-1ß, monocyte chemoattractant protein (MCP-1/CCL2), leptin, adiponectin, vascular cell adhesion molecule (VCAM-1/CD106) and intercellular adhesion molecule (ICAM-1/CD54) were measured. The homeostatic model assessment of IR (HOMA-IR) was calculated. We analyzed these variables according to the presence of AO and other metabolic syndrome (MetS) components. Results A total of 75.8% of children with AO had one or more risk factors for MetS. Children with AO had significantly higher body mass indexes (BMIs), insulin, HOMA-IR, TG, very low-density lipoprotein-cholesterol (VLDL-c) and TC/HDL-c ratio and lower HDL-c, compared to children without AO; but there were no differences in inflammatory markers. After adjusting for BMI, sex and age, the differences between groups were not significant for any variable. Waist circumference (WC) was correlated with insulin (r=0.547; p<0.001), TG (r=0.207; p=0.001), ICAM-1 (r=0.213; p=0.039), hs-CRP (r=0.189; p=0.015) and glucose (r=0.187; p=0.004). After adjusting for BMI, age and sex, AO plus one MetS component contributed to individual variation in glucose, insulin, HOMA-IR and TG. Conclusions AO in preschool children is associated with greater IR and atherogenic lipid profiles, although these findings seem to be more related to general obesity than just central obesity. In addition, our data suggest that IR may precede the elevation of systemic cytokines in obese children, unlike findings in adults. More studies in pediatric populations are needed to elucidate these associations.

The human CIB1-EVER1-EVER2 complex governs keratinocyte-intrinsic immunity to ß-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 ß-papillomaviruses (ß-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 α-HPV16 and γ-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 ß-HPVs of EV patients.

Inherited p40phox deficiency differs from classic chronic granulomatous disease.

Biallelic loss-of-function (LOF) mutations of the NCF4 gene, encoding the p40phox subunit of the phagocyte NADPH oxidase, have been described in only 1 patient. We report on 24 p40phox-deficient patients from 12 additional families in 8 countries. These patients display 8 different in-frame or out-of-frame mutations of NCF4 that are homozygous in 11 of the families and compound heterozygous in another. When overexpressed in NB4 neutrophil-like cells and EBV-transformed B cells in vitro, the mutant alleles were found to be LOF, with the exception of the p.R58C and c.120_134del alleles, which were hypomorphic. Particle-induced NADPH oxidase activity was severely impaired in the patients' neutrophils, whereas PMA-induced dihydrorhodamine-1,2,3 (DHR) oxidation, which is widely used as a diagnostic test for chronic granulomatous disease (CGD), was normal or mildly impaired in the patients. Moreover, the NADPH oxidase activity of EBV-transformed B cells was also severely impaired, whereas that of mononuclear phagocytes was normal. Finally, the killing of Candida albicans and Aspergillus fumigatus hyphae by neutrophils was conserved in these patients, unlike in patients with CGD. The patients suffer from hyperinflammation and peripheral infections, but they do not have any of the invasive bacterial or fungal infections seen in CGD. Inherited p40phox deficiency underlies a distinctive condition, resembling a mild, atypical form of CGD.

Mitochondrial superoxide mediates heat-induced apoptotic-like death in Leishmania infantum.

Previous studies have shown that heat stress triggers a process of programmed cell death in Leishmania infantum promastigotes that resembles apoptosis in higher eukaryotes. Even though this cell death process takes about 40 h to be completed, several early changes in the heat-stressed cells can be observed. Hyperpolarization of the parasite mitochondrion is the earliest event detected, which correlates with an increase in respiration rates and a concomitant increase in superoxide radical production. Induction of oxidative stress seems to mediate the heat-induced cell death process, as indicated by the partial prevention of parasite death observed when cell cultures are supplemented with N-acetyl-cysteine or glutathione. These antioxidants are able to diminish the concentration of superoxide radical but they do not prevent mitochondrial hyperpolarization. Treatment of the heat stressed parasites with the inhibitors of the mitochondrial respiration TTFA, antimycin A and KCN significantly decreases the production of superoxide radicals, which confirms the mitochondrial origin of this reactive oxygen species.

Síndrome metabólico en niños: problemática, componentes y criterios diagnósticos / Metabolic syndrome in children: issues, components and diagnostic criteria

RESUMEN Antecedentes el síndrome metabólico en niños aumenta el riesgo de diabetes mellitus tipo 2 y enfermedad cardiovascular en la adultez. Objetivo describir los componentes del síndrome metabólico en niños, su prevalencia y criterios diagnósticos propuestos por diferentes organizaciones y autores. Materiales y métodos se realizó una búsqueda bibliográfica en las siguientes bases de datos: Pubmed, Science Direct, Embase, Lilacs y Scielo. Resultados y discusión varias organizaciones han establecido definiciones para diagnosticar el síndrome metabólico en niños, algunas abordando criterios utilizados en adultos o adoptando puntos de corte derivados de poblaciones seleccionadas como niños obesos o sin incluir niños pre-adolescentes, aduciendo en estos últimos una baja prevalencia de alteraciones. Así, la prevalencia de este síndrome en una misma población puede variar (0,9 a 11,4%) según la definición empleada. Sin embargo, dicha prevalencia aumenta con el grado de obesidad infantil y se han demostrado prevalencias altas en pre-púberes, independiente de la clasificación empleada. Recientemente, se propuso usar puntajes continuos para mejorar la evaluación en niños. Conclusión los puntos de corte actualmente empleados ponderan de forma diferente los componentes del síndrome metabólico. Por tanto, se recomienda emplear percentiles según edad, sexo y población para cada componente y evaluar la utilidad de puntajes continuos en esta población.

ABSTRACT Background The metabolic syndrome in children increases the risk for type 2 diabetes and cardiovascular disease in adulthood. Aim To describe the components of metabolic syndrome in children, their prevalence, and diagnostic criteria proposed by different authors and organizations. Materials and methods A literature search of articles published in Pubmed, Science Direct, Embase, Lilacs and Scielo databases was conducted. Results and discussion: Several organizations have established definitions for metabolic syndrome diagnosis in children, some including criteria used for adults or adopting cutoffs derived from selected populations such as obese children or without including pre-adolescent children, arguing a low prevalence of alterations in these. Thus, the prevalence of metabolic syndrome in a particular population varies (0,9% to 11,4%) according to the definition used. However, this prevalence increases according to the obesity grade, and a high prevalence in pre-pubers has been reported, independent of the classification used. Recently, it was proposed the use of a continuous score to improve the metabolic syndrome evaluation in children. Conclusion: The cutoffs currently used give different weighting for each component of metabolic syndrome. Therefore, it is recommended the use of percentiles according to sex and age and population for each component and to evaluate the utility of continuous scores in this population.

p40phox: the last NADPH oxidase subunit.

The phagocytic NADPH-oxidase is a multiprotein system activated during the inflammatory response to produce superoxide anion (O2-), which is the substrate for formation of additional reactive oxygen species (ROS). The importance of this system for innate immunity is established by chronic granulomatous disease (CGD), a primary immunodeficiency caused by defects in the NADPH oxidase. In this review, we present and discuss recent knowledge about p40phox, the last NADPH oxidase component to be identified. Furthermore, its interaction with cellular pathways outside of the NADPH oxidase is discussed. Described in this review is evidence that p40phox participates in NADPH oxidase dynamics within cells, what is known about its role in the oxidase, the possibility that p40phox participates in non-NADPH oxidase processes in phagocytic and non-phagocytic cells and whether p40phox could mediate a similar function in other NADPH oxidases. An improved understanding of p40phox should provide new insights about NADPH oxidase, the physiology of phagocytic cells and the innate immune system.