Background

Atypical hemolytic-uremic syndrome (aHUS) consists of microangiopathic hemolytic anemia, thrombocytopenia and renal failure. aHUS is induced by uncontrolled complement activation and limited treatment options were at hand until the introduction of Eculizumab. Eculizumab is a complement C5 inhibitor that prevents formation of the membrane attack complex, but increases the risk for Meningococcal infections. Therefore, vaccination with the tetravalent vaccine against Meningococcal serogroup A, C, W-135, Y and MenB-4C is mandatory. In this study we investigated whether pediatric aHUS patients treated with Eculizumab show increased protection in a serum and whole blood killing assay after MenB-4C vaccination.

Methods

Neisseria meningitidis serogroup B (MenB) was incubated for 30 min with pre- and post- vaccination serum from 5 aHUS patients and binding of IgG, complement C3 and C5b-9 were determined using flowcytometry. Serum killing experiments were performed by incubating MenB for 30 min with autologous pre- and post- vaccination serum. Whole blood killing experiments were performed similarly, except MenB was incubated with serum in serum depleted whole blood from a heathy donors.

Results

Increased IgG and complement C3 binding to the Meningococcal surface was observed with serum post-MenB-4C vaccination. No complement C5b-9 binding to the Meningococcal surface was detected, which corresponded to a failure to kill the bacteria in a serum killing assay. In contrast to previous results in patients with complement deficiencies, no MenB-4C-vaccine induced increase in whole blood killing was observed in aHUS patients using Eculizumab.

Conclusions

Despite an MenB-4C-induced increase in IgG and complement C3 binding to the Meningococcal surface, there was no increase in complement or whole blood mediated killing. Suggesting that Eculizumab eliminates complement- as well as opsonophagocytosis-mediated killing of MenB in MenB-4C vaccinated aHUS patients.

Clinical Trial Registration

Background

Novel treatments have revolutionized the care and outcome of patients with JIA. DMARDs manage to control this disease, however data regarding response and long-term immunological memory to specific vaccines are lacking. Patients with rheumatic diseases are susceptible to infections due to their defective immune system and the immunosuppressive treatment received. We aimed at a comprehensive assessment of how anti-IL6 therapy may interfere with vaccine-specific-IgG titers in children with poly-articular JIA, by evaluating the persistence of specific-IgG levels during anti-IL6 treatment.

Methods

Monocentric cross-sectional controlled study was held over a period of three years, comprising 23 patients and 35 matched controls. All participants had completed their vaccination scheme. There were specific exclusion criteria set. Seroprotection rates as well as measles, rubella, tetanus, hepatitis B (HBV) and Hemophilus (Hib) specific-IgG titers were measured by ELISA and were expressed as Geometric mean Concentrations (GMC’s).

Results

The two groups had similar demographic characteristics, vaccination history and immunization status. Seroprotection rates for HBV, measles and Hib were similar between the two groups. However, seroprotection rates were lower in the poly-JIA group for tetanus and rubella compared to the control group (p<0.05). Moreover, tetanus and measles GMCs were significantly lower in the poly-JIA compared to the control group (p<0.05). The same was also evident for rubella to a more pronounced degree (p<0.01).

Conclusions

Children with poly-JIA who received anti-IL6 (tocilizumab) treatment appeared to have lower tetanus, measles and rubella specific-IgG titers. Further studies are required to address the question of long-term immunity conveyed by immunizations given at an early stage in children with rheumatic diseases on biologics, while proposing perfunctory studies to evaluate the effect of JIA and its associated treatment on lymphocyte ‘behavior’ and function.

Background

Recurrent respiratory tract infections (rRTIs) have considerable impact on health in young children and can lead to failure to thrive, developmental delays and pulmonary damage. IgA deficiency is the most common immunodeficiency in children with rRTIs, with prevalence rates in published cohorts between 1:4 and 1:65. However, the clinical relevance of prevalence studies is hampered by the lack of control groups and use of different reference values to define IgA deficiency.

Methods

In this case-control study we compare prevalence rates of IgA deficiency in Dutch children <7 years with rRTIs (n=426) and in controls (n=227) in whom IgA was determined for celiac disease screening. Children with confirmed celiac disease, underlying systemic diseases or immune disorders other than IgA deficiency were excluded. IgA deficiency was defined as an IgA concentration below the lower limit of the age-normalized reference interval based on several published reference values: Sanquin, Mayo clinic and CALIPER study.

Results

Both in children suffering from rRTIs and in controls prevalence rates of IgA deficiency differ greatly depending on which reference values are used (1.9%-9.2% and 2.2%-11.0%, respectively, see Figure). In multivariable analysis we observed trends towards higher OR for IgA deficiency in children suffering from rRTIs compared to controls for two of the reference values used (OR 1.69, p=0.07; OR 2.70, p=0.09; OR 1.50, p=0.28, see Figure).

Conclusions

Widely ranging published IgA reference values in literature, even when similar analysis methods are used, lead to large differences in prevalence rates. The lack of harmonization for IgA reference values in children complicates the proper comparison and interpretation of studies into the clinical relevance of IgA deficiency as well as the development of management guidelines for IgA deficient children suffering from recurrent infections.

Background

Mycobacterial infections are important causes of morbidity and mortality among children. Rare monogenic inborn errors of immunity were found to predispose to mycobacterial disease. The aim of this study was to identify genetic variants that confer susceptibility to mycobacterial disease in Moldavian children.

Methods

Whole exome sequencing (trio-based and candidate-gene approaches) was conducted in nine patients with mycobacterioses (eight with severe BCG complications and one with generalized tuberculosis) suspected for Mendelian Susceptibility to Mycobacterial Disease (MSMD). cDNA analysis was applied to validate the effect of mutations on pre-mRNA splicing in two patients.

Results

11 heterozygous variants in 7 MSMD-associated genes (STAT1, IFNGR1, IL23R, JAK1, TYK2, IL12B, and IL12RB1) were identified via candidate gene approach. Genes STAT1, IFNGR1 and IL12B were of particular interest, since STAT1 and IFNGR1 are responsible for autosomal dominant MSMD and IL12B comprises two novel mutations (c.877A>G (p.Lys293Glu) and c.89-14T>C) in a compound heterozygous state. The missense mutation c.40G>A (p.Val14Met) in IFNGR1 is a known variant with partial or complete IFNGR1 deficiency. The variant c.373-2A>C in STAT1 is a novel splice site mutation; cDNA analysis demonstrated that c.373-2A>C activates a cryptic splice site leading to skipping of the exon and partial intron retention in a patient with disseminated tuberculosis. In addition, 22 disease-associated variants in 14 presumed causative genes, including compound heterozygous variants in GBP2, TTN (two patients), GAL3ST2, HMCN1, ZCWPW1 and LRP1B, de novo variants in PPP1R9B and HEATR3, X-linked recessive variants in SRPX2, RBMXL3, H2BFM and KDM6A, and homozygous recessive variants in SIGLEC6 and IFNW were identified by trio-based analysis.

Conclusions

Our findings expand the spectrum of genetic variation possibly predisposing to mycobacterial infections in children.

Funding

Alexander von Humboldt Foundation and Hanover Unified Biobank.

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Background

Antifungal drug consumption has increased due to the recent increase of patients at risk for invasive fungal infections. Data on overuse of antifungal agents in children are limited both at national and European level. The aim of the study is to assess the pattern and time trends of antifungal consumption in pediatric and neonatal departments of a tertiary care level hospital.

Methods

A retrospective study was conducted in a pediatric intensive care unit (PICU), a neonatal intensive care unit (NICU), a pediatric hematology/oncology department (PONC), a pediatric surgery and two general pediatric departments, located in a single hospital. Data on antifungal consumption from 2010 to 2019 were obtained from the hospital pharmacy and expressed as defined daily doses per 100 bed-days (DDD/100BD) according to World Health Organization.

Results

Median total antifungal consumption exhibited a trend from 104.1 to 131DDD/100BD (p=0.1). Amphotericin B was the most commonly prescribed antifungal agent (45%) throughout study period and in all pediatric departments except PONC. The second most common antifungal used was voriconazole, whose consumption ranged from 21.8 to 40.8DDD/100BD and was mainly used in PONC. Consumption of both fluconazole and micafungin had a significant increase from 8.0 to 14.9DDD/100BD (p=0.004) and from 0.2 to 24.3DDD/100BD (p=0.02), respectively(fig.1). The highest antifungal use was found in PONC, followed by PICU and NICU.

Conclusions

Longitudinal analysis of antifungal consumption in pediatric and neonatal patients using the Daily Defined Dose methodology was feasible. Majority of antifungal agents were prescribed to pediatric oncology and critically ill neonates and children as expected. Recording the pattern and trends of antifungal use can contribute in identifying potential targets in order to improve their appropriate use in pediatric and neonatal population.