[Show abstract][Hide abstract] ABSTRACT: Granulocyte transfusions are used to treat neutropenic patients with life-threatening bacterial or fungal infections that do not respond to anti-microbial drugs. Donor neutrophils that have been mobilized with granulocyte-colony stimulating factor (G-CSF) and dexamethasone are functional in terms of antibacterial activity, but less is known about their fungal killing capacity. We investigated the neutrophil-mediated cytotoxic response against C. albicans and A. fumigatus in detail. Whereas G-CSF/dexamethasone-mobilized neutrophils appeared less mature as compared to neutrophils from untreated controls, these cells exhibited normal ROS production by the NADPH oxidase system and an unaltered granule mobilization capacity upon stimulation. G-CSF/dexamethasone-mobilized neutrophils efficiently inhibited A. fumigatus germination and killed Aspergillus and Candida hyphae, but the killing of C. albicans yeasts was distinctly impaired. Following normal Candida phagocytosis, analysis by mass spectrometry of purified phagosomes after fusion with granules demonstrated that major constituents of the antimicrobial granule components, including Major Basic Protein (MBP), were reduced. Purified MBP showed candidacidal activity, and neutrophil-like Crisp-Cas9 NB4-KO-MBP differentiated into phagocytes were impaired in Candida killing. Together, these findings indicate that G-CSF/dexamethasone-mobilized neutrophils for transfusion purposes have a selectively impaired capacity to kill Candida yeasts, as a consequence of an altered neutrophil granular content.
[Show abstract][Hide abstract] ABSTRACT: Objective:
To determine relevant Fc-gamma receptor (FcγR) polymorphisms in relation to susceptibility to SLE and LN, and to determine the functional consequences of genetic associations found.
Using multiplex ligation-dependent probe amplification, copy number regions (CNRs) and relevant known functional single nucleotide polymorphisms of FcγRII and FcγRIII were determined in a LN-enriched cohort of 266 Dutch Caucasian SLE patients and 919 healthy Caucasian controls. Expression of FcγRs on leukocytes was assessed using flow cytometry.
In multivariable analysis, low copy number of CNR1 (including FCGR3B; odds ratio (OR) 2.04; 95% CI: 1.29, 3.23), FCGR2A-131RR (OR 2.00; 95% CI: 1.33, 2.99), and the 2B.4 haplotype of FCGR2B (OR 1.59; 95% CI: 1.13, 2.24), but not FCGR2C open reading frame, were significantly (all P < 0.01) and independently associated with susceptibility to SLE. The 2B.4 haplotype was negatively associated with LN and led to surface expression of FcγRIIb on neutrophils and monocytes.
This study is the first to investigate the most relevant and functional single nucleotide polymorphisms and copy number variations of FcγRII and FcγRIII polymorphisms in one study population, enabling the determination of the individual contribution of each polymorphism in multivariable analysis. Three polymorphisms were shown to be independently associated with susceptibility to SLE. The novel findings of a negative association of the 2B.4 haplotype with LN, and increased expression of FcγRIIb on neutrophils and monocytes as a result of this 2B.4 haplotype warrant future research in the role of these cells and FcγRs in the pathogenesis of SLE and LN.
Full-text · Article · Jan 2016 · Rheumatology (Oxford, England)
[Show abstract][Hide abstract] ABSTRACT: Background:
Morbidity and mortality from primary varicella-zoster virus (VZV) infection is increased in immunocompromised children. Vaccination of VZV-seronegative cancer patients with live-attenuated varicella vaccine is safe when chemotherapy is interrupted. However, VZV vaccination without interruption of chemotherapy would be preferable.
To vaccinate VZV-seronegative pediatric oncology patients with live-attenuated VZV vaccine without interrupting their chemotherapy.
We performed a single-center prospective cohort study.
Thirty-one patients with either a hematological malignancy (n=24) or a solid tumor (n=7) were vaccinated early during their course of chemotherapy. VZV IgG seroconversion occurred in 14 of the 31 patients (45%) after one vaccination. Only 20 patients were revaccinated after 3 months. These were patients who did not seroconvert (5 patients) and patients who serocoverted (15 patients) to induce or sustain seropositivity. Of these 20 patients the final seroconversion rate was 70%. Seven out of the 31 patients (23%) developed a mild rash of which 5 were treated with antivirals and recovered completely without interrupting chemotherapy, and 2 recovered untreated. Of these 31 immunized patients 26 were available for cellular testing. After one vaccination 20 of 26 patients (77%) tested positive for VZV-specific CD4(+) T cells, of which 7 patients had remained VZV-seronegative. After the second vaccination 11 of 11 patients showed VZV-specific CD4(+) T cells to sustain positivity, although 4 remained VZV-seronegative.
This study indicates that live-attenuated VZV vaccine can be safely administered to closely monitored pediatric oncology patients without interruption of chemotherapy and adaptive immunity was induced despite incomplete seroconversion.
No preview · Article · Jan 2016 · Journal of clinical virology: the official publication of the Pan American Society for Clinical Virology
[Show abstract][Hide abstract] ABSTRACT: Neutrophils are known to play a pivotal role in the host defense against Aspergillus infections. This is illustrated by the prevalence of Aspergillus infections in patients with neutropenia or phagocyte functional defects, such as chronic granulomatous disease. However, the mechanisms by which human neutrophils recognize and kill Aspergillus are poorly understood. In this work, we have studied in detail which neutrophil functions, including neutrophil extracellular trap (NET) formation, are involved in the killing of Aspergillus fumigatus conidia and hyphae, using neutrophils from patients with well-defined genetic immunodeficiencies. Recognition of conidia involves integrin CD11b/CD18 (and not dectin-1), which triggers a PI3K-dependent nonoxidative intracellular mechanism of killing. When the conidia escape from early killing and germinate, the extracellular destruction of the Aspergillus hyphae needs opsonization by Abs and involves predominantly recognition via Fcγ receptors, signaling via Syk, PI3K, and protein kinase C to trigger the production of toxic reactive oxygen metabolites by the NADPH oxidase and myeloperoxidase. A. fumigatus induces NET formation; however, NETs did not contribute to A. fumigatus killing. Thus, our findings reveal distinct killing mechanisms of Aspergillus conidia and hyphae by human neutrophils, leading to a comprehensive insight in the innate antifungal response.
No preview · Article · Dec 2015 · The Journal of Immunology
[Show abstract][Hide abstract] ABSTRACT: Unlike resting CD4+ T cells, activated CD4+T cells are highly susceptible to infection of human immunodeficiency virus 1 (HIV-1). HIV-1 infects T cells and macrophages without activating the nucleic acid sensors and the anti-viral type I interferon response. Adenosine deaminase acting on RNA 1 (ADAR1) is an RNA editing enzyme that displays antiviral activity against several RNA viruses. Mutations in ADAR1 cause the autoimmune disorder Aicardi-Goutieères syndrome (AGS). This disease is characterized by an inappropriate activation of the interferon-stimulated gene response. Here we show that HIV-1 replication, in ADAR1-deficient CD4+T lymphocytes from AGS patients, is blocked at the level of protein translation. Furthermore, viral protein synthesis block is accompanied by an activation of interferon-stimulated genes. RNA silencing of ADAR1 in Jurkat cells also inhibited HIV-1 protein synthesis. Our data support that HIV-1 requires ADAR1 for efficient replication in human CD4+T cells.
[Show abstract][Hide abstract] ABSTRACT: Dendritic cells (DCs) are key initiators and regulators of the immune response. The development of the DC lineage and their subsets requires an orchestrated regulation of their transcriptional program. Gata1, a transcription factor expressed in several hematopoietic cell lineages, has been recently reported to be required for mouse DC development and function. In humans, GATA1 is involved in the lineage separation between monocyte-derived DCs and Langerhans cells (LC) and loss of GATA1 results in differentiation arrest at the monocyte stage. The hematopoietic GATA factors (i.e. Gata1, Gata2, Gata3) are known to regulate each other's expression and to function consecutively throughout lineage commitment (so-called GATA switch). In humans, mutations in GATA2 are causative of MonoMAC disease, a human immunodeficiency syndrome characterized by loss of DCs, monocytes, B and NK cells. However, additional data on the expression of hematopoietic GATA factors in the DC lineage is missing. In this study, we have characterized the expression of hematopoietic GATA factors in murine and human DCs and their expression dynamics upon TLR stimulation. We found that all hematopoietic GATA factors are expressed in DCs, but identified species-specific differences in the relative expression of each GATA factor, and how their expression fluctuates upon stimulation.
No preview · Article · Dec 2015 · Blood Cells Molecules and Diseases
[Show abstract][Hide abstract] ABSTRACT: Objectives:
To assess complement levels C1q, C2, C3 and C4 in children with pediatric-onset lupus during the quiescent stage of disease.
Thirty-four consecutive children with pediatric-onset SLE (onset below 12 years), in the quiescent stage were enrolled for the study. Twenty-nine age and sex matched healthy children were also enrolled for the purpose of comparison. Complement C1q and C2 levels were estimated by enzyme-linked immunosorbent assay (ELISA) whereas C3 and C4 were measured by end-point nephelometry. Genetic mutation analysis and functional assessment of classical complement pathway by ELISA were carried out in children with depressed levels of these complements. The study protocol was approved by the Institute Thesis Committee and the Institute Ethics Committee.
Mean complement C1q, C2, C3 and C4 levels were 50.32, 17.28, 1320 and 236 mg/L respectively. Levels of complements were low in 7/34 children with SLE. An early age at onset, low anti-dsDNA titres and predominant skin manifestations were noted in children with decreased levels of complement C1q. Mutation analysis of C1qA gene revealed a homozygous nonsense mutation: C1QA (NM_015991) c.622C>T, p.Q208X in one child. A homozygous acceptor splice site mutation at the -2 position of intron2 of C1QA (c.164-2A>C) was detected in another child. The age at onset of disease was early in both these children, at 2.5 and 1.5 years respectively.
Children with inherited deficiency of C1q and other early complement components present with early onset lupus that has a distinct clinical and immunological profile.
Full-text · Article · Nov 2015 · Journal of Clinical Immunology
[Show abstract][Hide abstract] ABSTRACT: Objective:
The current study aims to evaluate the neurologic state of perinatally HIV-infected children on combination antiretroviral therapy and to attain a better insight into the pathogenesis of their persistent neurologic and cognitive deficits.
We included perinatally HIV-infected children between 8 and 18 years and healthy controls matched for age, sex, ethnicity, and socioeconomic status. All participants underwent a 3.0 T MRI with 3D-T1-weighted, 3D-fluid-attenuated inversion recovery, and diffusion-weighted series for the evaluation of cerebral volumes, white matter hyperintensities (WMH), and white matter (WM) diffusion characteristics. Associations with disease-related parameters and cognitive performance were explored using linear regression models.
We included 35 cases (median age 13.8 years) and 37 controls (median age 12.1 years). A lower gray matter and WM volume, more WMH, and a higher WM diffusivity were observed in the cases. Within the HIV-infected children, a poorer clinical, immunologic, and virologic state were negatively associated with volumetric, WMH, and diffusivity markers.
In children with HIV, even when long-term clinically and virologically controlled, we found lower brain volumes, a higher WMH load, and poorer WM integrity compared to matched controls. These differences occur in the context of a poor cognitive performance in the HIV-infected group, and larger, longitudinal studies are needed to increase our understanding of the pathogenesis of cerebral injury in perinatally HIV-infected children.
[Show abstract][Hide abstract] ABSTRACT: Cancer immunotherapy has been revolutionised by the use monoclonal antibodies (mAb) that function through their interaction with Fc gamma receptors (FcγRs). The low-affinity FcγR genes are highly homologous, map to a complex locus at 1p23 and harbour single nucleotide polymorphisms (SNPs) and copy number variation (CNV) that can impact on receptor function and response to therapeutic mAbs. This complexity can hinder accurate characterisation of the locus. We therefore evaluated and optimised a suite of assays for the genomic analysis of the FcγR locus amenable to peripheral blood mononuclear cells and formalin-fixed paraffin-embedded (FFPE) material that can be employed in a high-throughput manner. Assessment of TaqMan genotyping for FCGR2A-131H/R, FCGR3A-158F/V and FCGR2B-232I/T SNPs demonstrated the need for additional methods to discriminate genotypes for the FCGR3A-158F/V and FCGR2B-232I/T SNPs due to sequence homology and CNV in the region. A multiplex ligation-dependent probe amplification assay provided high quality SNP and CNV data in PBMC cases, but there was greater data variability in FFPE material in a manner that was predicted by the BIOMED-2 multiplex PCR protocol. In conclusion, we have evaluated a suite of assays for the genomic analysis of the FcγR locus that are scalable for application in large clinical trials of mAb therapy. These assays will ultimately help establish the importance of FcγR genetics in predicting response to antibody therapeutics.
[Show abstract][Hide abstract] ABSTRACT: Sickle cell disease (SCD) is complicated by silent cerebral infarcts, visible as white matter hyperintensities (WMHs) on magnetic resonance imaging (MRI). Both local vaso-occlusion, elicited by endothelial dysfunction, and insufficiency of cerebral blood flow (CBF) have been proposed to be involved in the aetiology. We performed an explorative study to investigate the associations between WMHs and markers of endothelial dysfunction and CBF by quantifying WMH volume on 3·0 Tesla MRI. We included 40 children with HbSS or HbSβ(0) thalassaemia, with a mean age of 12·1 ± 2·6 years. Boys demonstrated an increased risk for WMHs (odds ratio 4·5, 95% confidence interval 1·2-17·4), unrelated to glucose-6-phosphate dehydrogenase deficiency. In patients with WMHs, lower fetal haemoglobin (HbF) was associated with a larger WMH volume (regression coefficient = -0·62, R(2) = 0·25, P = 0·04). Lower ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) levels were associated with lower CBF in the white matter (regression coefficient = 0·07, R(2) = 0·15, P = 0·03), suggesting that endothelial dysfunction could potentially hamper CBF. The findings of our explorative study suggest that a high level of HbF may be protective for WMHs and that endothelial dysfunction may contribute to the development of WMHs by reducing CBF.
No preview · Article · Oct 2015 · British Journal of Haematology
[Show abstract][Hide abstract] ABSTRACT: Patients with mutations of the recombination-activating genes (RAG) present with diverse clinical phenotypes, including severe combined immune deficiency (SCID), autoimmunity, and inflammation. However, the incidence and extent of immune dysregulation in RAG-dependent immunodeficiency have not been studied in detail. Here, we have demonstrated that patients with hypomorphic RAG mutations, especially those with delayed-onset combined immune deficiency and granulomatous/autoimmune manifestations (CID-G/AI), produce a broad spectrum of autoantibodies. Neutralizing anti-IFN-α or anti-IFN-ω antibodies were present at detectable levels in patients with CID-G/AI who had a history of severe viral infections. As this autoantibody profile is not observed in a wide range of other primary immunodeficiencies, we hypothesized that recurrent or chronic viral infections may precipitate or aggravate immune dysregulation in RAG-deficient hosts. We repeatedly challenged Rag1S723C/S723C mice, which serve as a model of leaky SCID, with agonists of the virus-recognizing receptors TLR3/MDA5, TLR7/-8, and TLR9 and found that this treatment elicits autoantibody production. Altogether, our data demonstrate that immune dysregulation is an integral aspect of RAG-associated immunodeficiency and indicate that environmental triggers may modulate the phenotypic expression of autoimmune manifestations.
Full-text · Article · Oct 2015 · The Journal of clinical investigation
[Show abstract][Hide abstract] ABSTRACT: Background:
Kawasaki disease (KD) is an acute pediatric vasculitis with coronary artery aneurysms (CAA) as its main complication. Concerns have been raised regarding the possibility of a predisposition of KD to premature cardiovascular disease (CVD) risk later in life. Our aim was to assess carotid intima-media thickness (cIMT), as a surrogate marker of CVD risk, in patients with a history of KD compared with unaffected controls.Methods and Results:B-mode ultrasound cIMT measurements were performed in 168 patients with a history of KD, and 82 controls; 7 patients were excluded because of incomplete cIMT assessments. Mean cIMT (±SD) was increased in patients with KD compared with controls (0.378±0.030 mm vs. 0.360±0.027 mm, respectively; P adjusted <0.0001). If the cIMTs of CAA-negative patients and controls were plotted against age, increased cIMT was only apparent at young age. In patients with CAA, increased cIMT was observed over the entire age range.
Our findings show that arterial wall thickening is more apparent in patients with a history of KD as compared with controls. In CAA-negative patients, cIMT is indistinguishable from controls at older age, whereas an increased cIMT is observed at any age in patients with CAA, suggesting a more general and severe effect of KD on the arterial wall.
Preview · Article · Oct 2015 · Circulation Journal
[Show abstract][Hide abstract] ABSTRACT: Combination antiretroviral therapy (cART) can alter HIV infection in children into a chronic condition. Studies investigating health-related quality of life (HRQoL) in HIV-infected children are scarce, and lacking from Western Europe. This study aimed to compare the HRQoL of clinically stable perinatally HIV-infected children to healthy, socioeconomically (SES)-matched controls as well as the Dutch norm population, and to explore associations between HIV and cART-related factors with HRQoL. HIV-infected and healthy children aged 8-18 years completed the Pediatric Quality of Life Inventory™ 4.0 (PedsQL™). We determined differences between groups on PedsQL™ mean scores, and the proportion of children with an impaired HRQoL per group (≥1 SD lower than the Dutch norm population). Logistic regression models were used to explore associations between disease-related factors and HRQoL impairment. In total, 33 HIV-infected and 37 healthy children were included. There were no differences in the mean PedsQL™ subscales between HIV-infected children and both control groups. The proportion of children with an impaired HRQoL was higher in the HIV-infected group (27%) as compared to the healthy control group (22%) and the Dutch norm (14%) on the school functioning subscale (HIV vs. Dutch norm: P = .045). Mean scores of HRQoL of perinatally HIV-infected children in the Netherlands were not different from a SES-matched control group, or from the Dutch norm population. However, the HIV-infected group did contain more children with HRQoL impairment, suggesting that HIV-infected children in the Netherlands are still more vulnerable to a compromised HRQoL.
[Show abstract][Hide abstract] ABSTRACT: To evaluate enhancing synovial thickness upon contrast-enhanced magnetic resonance imaging (MRI) of the knee in children unaffected by clinical arthritis compared with clinically active juvenile idiopathic arthritis (JIA) patients. A secondary objective was optimization of the scoring method based on maximizing differences on MRI between these groups.
Twenty-five children without history of joint complaints nor any clinical signs of joint inflammation were age/sex-matched with 25 clinically active JIA patients with arthritis of at least one knee. Two trained radiologists, blinded for clinical status, independently evaluated location and extent of enhancing synovial thickness with the validated Juvenile Arthritis MRI Scoring system (JAMRIS) on contrast-enhanced axial fat-saturated T1-weighted MRI of the knee.
Enhancing synovium (≥2 mm) was present in 13 (52 %) unaffected children. Using the total JAMRIS score for synovial thickening, no significant difference was found between unaffected children and active JIA patients (p = 0.091). Additional weighting of synovial thickening at the JIA-specific locations enabled more sensitive discrimination (p = 0.011).
Mild synovial thickening is commonly present in the knee of children unaffected by clinical arthritis. The infrapatellar and cruciate ligament synovial involvement were specific for JIA, which-in a revised JAMRIS-increases the ability to discriminate between JIA and unaffected children.
• Synovial inflammation is the primary disease feature in juvenile idiopathic arthritis (JIA). • Appearance of the synovium on contrast-enhanced MRI in unaffected children is unknown. • Validation of existing scoring methods requires comparison between JIA and unaffected children. • Mild enhancing synovial thickening was detected in half of the unaffected children. • Location-weighting for JIA-specific locations increased discriminative value of the scoring methods (p = 0.011).
Full-text · Article · Aug 2015 · European Radiology
[Show abstract][Hide abstract] ABSTRACT: Kawasaki disease (KD) is a paediatric vasculitis with coronary artery aneurysms (CAA) as its main complication. Two guidelines exist regarding the follow-up of patients after KD, by the American Heart Association and the Japanese Circulation Society. After the acute phase, CAA-negative patients are checked for cardiovascular risk assessment or with ECG and echocardiography until 5 years after the disease. In CAA-positive patients, monitoring includes myocardial perfusion imaging, conventional angiography and CT-angiography. However, the invasive nature and high radiation exposure do not reflect technical advances in cardiovascular imaging. Newer techniques, such as cardiac MRI, are mentioned but not directly implemented in the follow-up. Cardiac MRI can be performed to identify CAA, but also evaluate functional abnormalities, ischemia and previous myocardial infarction including adenosine stress-testing. Low-dose CT angiography can be implemented at a young age when MRI without anaesthesia is not feasible. CT calcium scoring with a very low radiation dose can be useful in risk stratification years after the disease. By incorporating newer imaging techniques, detection of CAA will be improved while reducing radiation burden and potential complications of invasive imaging modalities. Based on the current knowledge, a possible pathway to follow-up patients after KD is introduced.
• Kawasaki disease is a paediatric vasculitis with coronary aneurysms as major complication.
• Current guidelines include invasive, high-radiation modalities not reflecting new technical advances.
• Cardiac MRI can provide information on coronary anatomy as well as cardiac function.
• (Low-dose) CT-angiography and CT calcium score can also provide important information.
• Current guidelines for follow-up of patients with KD need to be revised.
Full-text · Article · Jul 2015 · Insights into Imaging