72 results found
Kuiper R, Wright VJ, Habgood-Coote D, et al., 2023, Bridging a diagnostic Kawasaki disease classifier from a microarray platform to a qRT-PCR assay, Pediatric Research, Vol: 93, Pages: 559-569, ISSN: 0031-3998
BACKGROUND: Kawasaki disease (KD) is a systemic vasculitis that mainly affects children under 5 years of age. Up to 30% of patients develop coronary artery abnormalities, which are reduced with early treatment. Timely diagnosis of KD is challenging but may become more straightforward with the recent discovery of a whole-blood host response classifier that discriminates KD patients from patients with other febrile conditions. Here, we bridged this microarray-based classifier to a clinically applicable quantitative reverse transcription-polymerase chain reaction (qRT-PCR) assay: the Kawasaki Disease Gene Expression Profiling (KiDs-GEP) classifier. METHODS: We designed and optimized a qRT-PCR assay and applied it to a subset of samples previously used for the classifier discovery to reweight the original classifier. RESULTS: The performance of the KiDs-GEP classifier was comparable to the original classifier with a cross-validated area under the ROC curve of 0.964 [95% CI: 0.924-1.00] vs 0.992 [95% CI: 0.978-1.00], respectively. Both classifiers demonstrated similar trends over various disease conditions, with the clearest distinction between individuals diagnosed with KD vs viral infections. CONCLUSION: We successfully bridged the microarray-based classifier into the KiDs-GEP classifier, a more rapid and more cost-efficient qRT-PCR assay, bringing a diagnostic test for KD closer to the hospital clinical laboratory. IMPACT: A diagnostic test is needed for Kawasaki disease and is currently not available. We describe the development of a One-Step multiplex qRT-PCR assay and the subsequent modification (i.e., bridging) of the microarray-based host response classifier previously described by Wright et al. The bridged KiDs-GEP classifier performs well in discriminating Kawasaki disease patients from febrile controls. This host response clinical test for Kawasaki disease can be adapted to the hospital clinical laboratory.
Tan CD, van der Walle EEPL, Vermont CL, et al., 2022, Guideline adherence in febrile children below 3 months visiting European Emergency Departments: an observational multicenter study, European Journal of Pediatrics, Vol: 181, Pages: 4199-4209, ISSN: 0340-6199
Febrile children below 3 months have a higher risk of serious bacterial infections, which often leads to extensive diagnostics and treatment. There is practice variation in management due to differences in guidelines and their usage and adherence. We aimed to assess whether management in febrile children below 3 months attending European Emergency Departments (EDs) was according to the guidelines for fever. This study is part of the MOFICHE study, which is an observational multicenter study including routine data of febrile children (0-18 years) attending twelve EDs in eight European countries. In febrile children below 3 months (excluding bronchiolitis), we analyzed actual management compared to the guidelines for fever. Ten EDs applied the (adapted) NICE guideline, and two EDs applied local guidelines. Management included diagnostic tests, antibiotic treatment, and admission. We included 913 children with a median age of 1.7 months (IQR 1.0-2.3). Management per ED varied as follows: use of diagnostic tests 14-83%, antibiotic treatment 23-54%, admission 34-86%. Adherence to the guideline was 43% (374/868) for blood cultures, 29% (144/491) for lumbar punctures, 55% (270/492) for antibiotic prescriptions, and 67% (573/859) for admission. Full adherence to these four management components occurred in 15% (132/868, range 0-38%), partial adherence occurred in 56% (484/868, range 35-77%). CONCLUSION: There is large practice variation in management. The guideline adherence was limited, but highest for admission which implies a cautious approach. Future studies should focus on guideline revision including new biomarkers in order to optimize management in young febrile children. WHAT IS KNOWN: • Febrile children below 3 months have a higher risk of serious bacterial infections, which often leads to extensive diagnostics and treatment. • There is practice variation in management of young febrile children due to differences in guideline
Kumar V, Pouw RB, Autio M, et al., 2022, Variation in CFHR3 determines susceptibility to meningococcal disease by controlling factor H concentrations, AMERICAN JOURNAL OF HUMAN GENETICS, Vol: 109, Pages: 1680-1691, ISSN: 0002-9297
Jackson H, Calle IR, Broderick C, et al., 2022, Characterisation of the blood RNA host response underpinning severity in COVID-19 patients, Scientific Reports, Vol: 12, ISSN: 2045-2322
Infection with SARS-CoV-2 has highly variable clinical manifestations, ranging from asymptomatic infection through to life-threatening disease. Host whole blood transcriptomics can offer unique insights into the biological processes underpinning infection and disease, as well as severity. We performed whole blood RNA Sequencing of individuals with varying degrees of COVID-19 severity. We used differential expression analysis and pathway enrichment analysis to explore how the blood transcriptome differs between individuals with mild, moderate, and severe COVID-19, performing pairwise comparisons between groups. Increasing COVID-19 severity was characterised by an abundance of inflammatory immune response genes and pathways, including many related to neutrophils and macrophages, in addition to an upregulation of immunoglobulin genes. Our insights into COVID-19 severity reveal the role of immune dysregulation in the progression to severe disease and highlight the need for further research exploring the interplay between SARS-CoV-2 and the inflammatory immune response.
van Beek AE, Pouw RB, Wright VJ, et al., 2022, Low levels of factor H family proteins during meningococcal disease indicate systemic processes rather than specific depletion by neisseria meningitidis, Frontiers in Immunology, Vol: 13, ISSN: 1664-3224
Neisseria meningitidis, the causative agent of meningococcal disease (MD), evades complement-mediated clearance upon infection by ‘hijacking’ the human complement regulator factor H (FH). The FH protein family also comprises the homologous FH-related (FHR) proteins, hypothesized to act as antagonists of FH, and FHR-3 has recently been implicated to play a major role in MD susceptibility. Here, we show that the circulating levels of all FH family proteins, not only FH and FHR-3, are equally decreased during the acute illness. We did neither observe specific consumption of FH or FHR-3 by N. meningitidis, nor of any of the other FH family proteins, suggesting that the globally reduced levels are due to systemic processes including dilution by fluid administration upon admission and vascular leakage. MD severity associated predominantly with a loss of FH rather than FHRs. Additionally, low FH levels associated with renal failure, suggesting insufficient protection of host tissue by the active protection by the FH protein family, which is reminiscent of reduced FH activity in hemolytic uremic syndrome. Retaining higher levels of FH may thus limit tissue injury during MD.
Channon-Wells S, Coote D, Wright V, et al., 2022, VALIDATION OF TRANSCRIPTOMIC SIGNATURES FOR FEBRILE CHILDREN USING NANOSTRING TECHNOLOGY AND EXPLORATION OF MULTI-CLASS PREDICTION MODELS, The European Society For Paediatric Infectious Diseases Conference 2022
Backgrounds: Many host transcript signatures for paediatric inflammatory and infectious diseases are in development, but require validation in independent cohorts; their translation to clinically useful test platforms lags behind discovery. We used NanoString technology to efficiently validate multiple signatures in parallel and explore the potential for more sophisticated multi-class classification models. Methods: We validated five transcriptomic diagnostic signatures using prospectively recruited patients from multiple paediatric cohorts. Final phenotypes were assigned using pre-agreed definitions after review of clinical and laboratory data. We quantified 69 transcripts on a custom NanoString nCounter cartridge, normalising expression values using reference genes. Signature performance was assessed using Area Under ROC Curve (AUC) statistics. We explored two approaches to multiclassification diagnostics to develop proof-of-concept methods: a mixed test combining four independent one-vs-all models, and a multinomial model. Results: Our cohort of 92 paediatric patients included 23 definite bacterial and 20 definite viral infections, 15 Kawasaki disease, 18 with tuberculosis and 16 healthy controls. The signatures achieved AUCs above 0.82 (Table 1), with confidence intervals overlapping those of the respective discovery studies. However, performance declined in all signatures when tasked with differentiating additional groups. For example, the single-transcript BATF2 had AUC of 0.910 differentiating TB from healthy individuals, reducing to 0.745 when differentiating TB from other febrile diseases. In comparison, the multinomial approach identified a 24-transcript model that correctly classified all 76 non-control patients (0% in-sample error), outperforming the mixed-model (19 transcripts, 19.8% in-sample error).
Hoggart C, Shimizu C, Galassini R, et al., 2021, Identification of novel locus associated with coronary artery aneurysms and validation of loci for susceptibility to Kawasaki disease, European Journal of Human Genetics, Vol: 29, Pages: 1734-1744, ISSN: 1018-4813
Kawasaki disease (KD) is a paediatric vasculitis associated with coronary artery aneurysms (CAA). Genetic variants influencing susceptibility to KD have been previously identified, but no risk alleles have been validated that influence CAA formation. We conducted a genome-wide association study (GWAS) for CAA in KD patients of European descent with 200 cases and 276 controls. A second GWAS for susceptibility pooled KD cases with healthy paediatric controls from vaccine trials in the UK (n = 1609). Logistic regression mixed models were used for both GWASs. The susceptibility GWAS was meta-analysed with 400 KD cases and 6101 controls from a previous European GWAS, these results were further meta-analysed with Japanese GWASs at two putative loci. The CAA GWAS identified an intergenic region of chromosome 20q13 with multiple SNVs showing genome-wide significance. The risk allele of the most associated SNV (rs6017006) was present in 13% of cases and 4% of controls; in East Asian 1000 Genomes data, the allele was absent or rare. Susceptibility GWAS with meta-analysis with previously published European data identified two previously associated loci (ITPKC and FCGR2A). Further meta-analysis with Japanese GWAS summary data from the CASP3 and FAM167A genomic regions validated these loci in Europeans showing consistent effects of the top SNVs in both populations. We identified a novel locus for CAA in KD patients of European descent. The results suggest that different genes determine susceptibility to KD and development of CAA and future work should focus on the function of the intergenic region on chromosome 20q13.
Li HK, Kaforou M, Rodriguez-Manzano J, et al., 2021, Discovery and validation of a 3-gene signature to distinguish COVID-19 and other viral infections in emergency infectious disease presentations; a case-control then observational cohort study, The Lancet Microbe, Vol: 2, Pages: 594-603, ISSN: 2666-5247
Background: Emergency admissions for infection often lack initial diagnostic certainty. COVID-19 has highlighted a need for novel diagnostic approaches to indicate likelihood of viral infection in a pandemic setting. We sought to derive and validate a blood transcriptional signature to detect viral infections including COVID-19 among adults with suspected infection presenting to the Emergency Department (ED).Methods: Blood RNA sequencing was performed on a discovery cohort of adults attending the ED with suspected infection who had subsequently-confirmed viral, bacterial, or no infection diagnoses. Differentially expressed host genes were subjected to feature selection to derive the most parsimonious discriminating signature. RT-qPCR validation of the signature was then performed in a prospective cohort of ED patients presenting with undifferentiated fever, and a second case-control cohort of ED patients with COVID-19 or bacterial infection. Signature performance was assessed by calculating area under receiver-operating characteristic curves (AUC-ROCs), sensitivities, and specificities.Findings: A 3-gene transcript signature was derived from the discovery cohort of 56 bacterial and 27 viral infection cases. In the validation cohort of 200 cases, the signature differentiated bacterial from viral infections with an AUC-ROC of 0.976 (95% CI: 0.919-1.000), sensitivity 97.3% and specificity of 100%. The AUC-ROC for C-reactive protein (CRP) and leucocyte count (WCC) was 0.833 (95% CI: 0.694-0.944) and 0.938 (95% CI: 0.840-0.986) respectively. The signature achieved higher net benefit in decision curve analysis than either CRP or WCC for discriminating viral infections from all other cases. In the second validation analysis the signature discriminated 35 bacterial infections from 34 SARS-CoV-2 positive COVID-19 infections with AUC-ROC of 0.953 (95% CI: 0.893-0.992), sensitivity 88.6% and specificity of 94.1%.Interpretation: This novel 3-gene signature discriminates viral i
Nijman R, Oostenbrink R, Moll HA, et al., 2021, A novel framework for phenotyping children with suspected or confirmed infection for future biomarker studies, Frontiers in Pediatrics, Vol: 9, Pages: 1-18, ISSN: 2296-2360
Background: The limited diagnostic accuracy of biomarkers in children at risk of a serious bacterial infection (SBI) might be due to the imperfect reference standard of SBI. We aimed to evaluate the diagnostic performance of a new classification algorithm for biomarker discovery in children at risk of SBI.Methods: We used data from five previously published, prospective observational biomarker discovery studies, which included patients aged 0– <16 years: the Alder Hey emergency department (n = 1,120), Alder Hey pediatric intensive care unit (n = 355), Erasmus emergency department (n = 1,993), Maasstad emergency department (n = 714) and St. Mary's hospital (n = 200) cohorts. Biomarkers including procalcitonin (PCT) (4 cohorts), neutrophil gelatinase-associated lipocalin-2 (NGAL) (3 cohorts) and resistin (2 cohorts) were compared for their ability to classify patients according to current standards (dichotomous classification of SBI vs. non-SBI), vs. a proposed PERFORM classification algorithm that assign patients to one of eleven categories. These categories were based on clinical phenotype, test outcomes and C-reactive protein level and accounted for the uncertainty of final diagnosis in many febrile children. The success of the biomarkers was measured by the Area under the receiver operating Curves (AUCs) when they were used individually or in combination.Results: Using the new PERFORM classification system, patients with clinically confident bacterial diagnosis (“definite bacterial” category) had significantly higher levels of PCT, NGAL and resistin compared with those with a clinically confident viral diagnosis (“definite viral” category). Patients with diagnostic uncertainty had biomarker concentrations that varied across the spectrum. AUCs were higher for classification of “definite bacterial” vs. “definite viral” following the PERFORM algorithm than using the “SBI” vs. “non-SBI” c
Jackson H, Menikou S, Hamilton M, et al., 2021, Kawasaki Disease patient stratification and pathway analysis based on host transcriptomic and proteomic profiles, International Journal of Molecular Sciences, Vol: 11, Pages: 1-24, ISSN: 1422-0067
The aetiology of Kawasaki Disease (KD), an acute inflammatory disorder of childhood, remains unknown despite various triggers of KD having been proposed. Host ‘omic profiles offer insights into the host response to infection and inflammation, with the interrogation of multiple ‘omic levels in parallel providing a more comprehensive picture. We used differential abundance analysis, pathway analysis, clustering and classification techniques to explore whether the host response in KD is more similar to the response to bacterial or viral infection at the transcriptomic and proteomic levels through comparison of ‘omic profiles from children with KD to those with bacterial and viral infections. Pathways activated in patients with KD included those involved in anti-viral and anti-bacterial responses. Unsupervised clustering showed that the majority of KD patients clustered with bacterial patients on both ‘omic levels, whilst application of diagnostic signatures specific for bacterial and viral infections revealed that many transcriptomic KD samples had low probabilities of having bacterial or viral infections, suggesting that KD may be triggered by a different process not typical of either common bacterial or viral infections. Clustering based on the transcriptomic and proteomic responses during KD revealed three clusters of KD patients on both ‘omic levels, suggesting heterogeneity within the inflammatory response during KD. The observed heterogeneity may reflect differences in the host response to a common trigger, or variation dependent on different triggers of the condition.
Gliddon H, Kaforou M, Alikian M, et al., 2021, Identification of reduced host transcriptomic signatures for tuberculosis disease and digital PCR-based validation and quantification, Frontiers in Immunology, Vol: 12, ISSN: 1664-3224
Recently, host whole blood gene expression signatures have been identified for diagnosis of tuberculosis (TB). Absolute quantification of the concentrations of signature transcripts in blood have not been reported, but would facilitate diagnostic test development. To identify minimal transcript signatures, we applied a transcript selection procedure to microarray data from African adults comprising 536 patients with TB, other diseases (OD) and latent TB (LTBI), divided into training and test sets. Signatures were further investigated using reverse transcriptase (RT)—digital PCR (dPCR). A four-transcript signature (GBP6, TMCC1, PRDM1, and ARG1) measured using RT-dPCR distinguished TB patients from those with OD (area under the curve (AUC) 93.8% (CI95% 82.2–100%). A three-transcript signature (FCGR1A, ZNF296, and C1QB) differentiated TB from LTBI (AUC 97.3%, CI95%: 93.3–100%), regardless of HIV. These signatures have been validated across platforms and across samples offering strong, quantitative support for their use as diagnostic biomarkers for TB.
Borghesi A, Trück J, Asgari S, et al., 2020, Whole-exome sequencing for the identification of rare variants in primary immunodeficiency genes in children with sepsis - a prospective population-based cohort study., Clinical Infectious Diseases, Vol: 71, Pages: e614-e623, ISSN: 1058-4838
BACKGROUND: The role of primary immunodeficiencies (PID) in susceptibility to sepsis remains unknown. It is unclear whether children with sepsis benefit from genetic investigations. We hypothesized that sepsis may represent the first manifestation of underlying PID. We applied whole-exome sequencing (WES) to a national cohort of children with sepsis to identify rare, predicted pathogenic variants in PID genes. METHODS: Multicenter population-based prospective study including previously healthy children ≥28 days and <17 years admitted with blood culture-proven sepsis. Using a stringent variant filtering procedure, analysis of WES data was restricted to rare, predicted pathogenic variants in 240 PID genes for which increased susceptibility to bacterial infection has been reported. RESULTS: 176 children presenting with 185 sepsis episodes underwent WES (median age 52 months, IQR 15.4-126.4). 41 unique predicted pathogenic PID variants (1 homozygous, 5 hemizygous, and 35 heterozygous) were found in 35/176 (20%) patients, including 3/176 (2%) patients carrying variants which were previously reported to lead to PID. The variants occurred in PID genes across all 8 PID categories as defined by the International Union of Immunological Societies. We did not observe a significant correlation between clinical or laboratory characteristics of patients and the presence or absence of PID variants. CONCLUSIONS: Applying WES to a population-based cohort of previously healthy children with bacterial sepsis detected Variants of Uncertain Significance in PID genes in one out of five children. Future studies need to investigate the functional relevance of these variants to determine whether variants in PID genes contribute to pediatric sepsis susceptibility.
Channon-Wells S, O'Connor D, Valente-Pinto M, et al., 2020, RNA EXPRESSION RELIABLY DISTINGUISHES BACTERIAL INFECTION FROM TRANSIENT VACCINE REACTIONS IN YOUNG CHILDREN, The European Society For Paediatric Infectious Diseases Conference 2020
Background: Current diagnostics do not reliably differentiate serious bacterial infections from transient vaccine reactions in febrile young infants. We hypothesised that analysis of host RNA-expression could provide novel diagnostics for this specific common clinical setting. Methods: RNA-sequencing was used to compare whole-blood RNA expression in healthy postvaccination infants at 4-months of age with gene expression in young children under 5 years with definite bacterial infection from two distinct cohorts. Vaccinated infants received routine vaccinations according to the UK vaccination schedule, with half also receiving the 4CMenB vaccine. Batch correction was performed using the COCONUT R-package. Cases were split into training and test sets. To distinguish bacterial infection from vaccine reaction three minimal transcript signatures were selected using differential expression analysis and three separate machine learning tools on the training set. The performance of these signatures was evaluated on the test set. Results: On the training set of 86 children (42 infections, 44 post-vaccination) we identified three signatures with 3-, 6- and 11-transcripts. In the test set (52 children) all three signatures performed similarly, with AUCs all above 0.99 (Figure 1). The best performing signature (11-transcripts) distinguished bacterial infection from vaccine reaction with 97% sensitivity and 93% specificity in the test set, outperforming both CRP and WCC in the whole cohort (CRP: sensitivity 83%, specificity 90%). Conclusions: This preliminary work has identified novel transcript-sets that discriminate bacterial infection from vaccine reaction. Further testing is required to validate these findings. Our aim is to develop a quantitative PCR assay for clinical use, to help minimise admissions and antibiotic administrations in children suffering from a transient vaccine response. Clinical Trial Registration: Not applicable
Zandstra J, van de Geer A, Tanck MWT, et al., 2020, Biomarkers for the discrimination of acute kawasaki disease from infections in childhood, Frontiers in Pediatrics, Vol: 8, ISSN: 2296-2360
Background: Kawasaki disease (KD) is a vasculitis of early childhood mimicking several infectious diseases. Differentiation between KD and infectious diseases is essential as KD's most important complication—the development of coronary artery aneurysms (CAA)—can be largely avoided by timely treatment with intravenous immunoglobulins (IVIG). Currently, KD diagnosis is only based on clinical criteria. The aim of this study was to evaluate whether routine C-reactive protein (CRP) and additional inflammatory parameters myeloid-related protein 8/14 (MRP8/14 or S100A8/9) and human neutrophil-derived elastase (HNE) could distinguish KD from infectious diseases.Methods and Results: The cross-sectional study included KD patients and children with proven infections as well as febrile controls. Patients were recruited between July 2006 and December 2018 in Europe and USA. MRP8/14, CRP, and HNE were assessed for their discriminatory ability by multiple logistic regression analysis with backward selection and receiver operator characteristic (ROC) curves. In the discovery cohort, the combination of MRP8/14+CRP discriminated KD patients (n = 48) from patients with infection (n = 105), with area under the ROC curve (AUC) of 0.88. The HNE values did not improve discrimination. The first validation cohort confirmed the predictive value of MRP8/14+CRP to discriminate acute KD patients (n = 26) from those with infections (n = 150), with an AUC of 0.78. The second validation cohort of acute KD patients (n = 25) and febrile controls (n = 50) showed an AUC of 0.72, which improved to 0.84 when HNE was included.Conclusion: When used in combination, the plasma markers MRP8/14, CRP, and HNE may assist in the discrimination of KD from both proven and suspected infection.
Mashbat B, Bellos E, Hodeib S, et al., 2020, A rare mutation in SPLUNC1 underlies meningococcal disease affecting bacterial adherence and invasion, Clinical Infectious Diseases, Vol: 70, Pages: 2045-2053, ISSN: 1058-4838
BackgroundNeisseriameningitidis (Nm) is a nasopharyngeal commensal carried by healthy individuals. However, invasive infections occurs in a minority of individuals, with devastating consequences. There is evidence that common polymorphisms are associated with invasive meningococcal disease (IMD) but the contribution of rare variants other than complement has not been determined.MethodsWe identified familial cases of IMD in the UK meningococcal disease study and the European Union Life-threatening Infectious Disease Study. Candidate genetic variants were identified by whole exome sequencing of two patients with familial IMD. Candidate variants were further validated by in vitro assays.ResultsExomes of two siblings with IMD identified a novel heterozygous missense mutation in BPIFA1/SPLUNC1. Sequencing of 186 other non-familial cases identified another unrelated IMD patient with the same mutation. SPLUNC1 is an innate immune defence protein expressed in the nasopharyngeal epithelia, however, its role in invasive infections is unknown. In vitro assays demonstrated that recombinant SPLUNC1 inhibits biofilm formation by Nm, and impedes Nm adhesion and invasion of human airway cells. The dominant negative mutant rSPLUNC1 (p.G22E) showed reduced anti-biofilm activity, increased meningococcal adhesion and invasion of cells compared with wild type SPLUNC1.ConclusionsA mutation in SPLUNC1 affecting mucosal attachment, biofilm formation and invasion of mucosal epithelial cells is a new genetic cause of meningococcal disease.
Wang X, Nijman R, Camuzeaux S, et al., 2019, Plasma lipid profiles discriminate bacterial from viral infection in febrile children, Scientific Reports, Vol: 9, ISSN: 2045-2322
Fever is the most common reason that children present to Emergency Departments. Clinical signs and symptoms suggestive of bacterial infection are often non-specific, and there is no definitive test for the accurate diagnosis of infection. The ‘omics’ approaches to identifying biomarkers from the host-response to bacterial infection are promising. In this study, lipidomic analysis was carried out with plasma samples obtained from febrile children with confirmed bacterial infection (n=20) and confirmed viral infection (n=20). We show for the first time that bacterial and viral infection produces distinct profile in the host lipidome. Some species of glycerophosphoinositol, sphingomyelin, lysophosphatidylcholine and cholesterol sulfate were higher in the confirmed virus infected group, while some species of fatty acids, glycerophosphocholine, glycerophosphoserine, lactosylceramide and bilirubin were lower in the confirmed virus infected group when compared with confirmed bacterial infected group..A combination of three lipids achieved an area under the receiver operating characteristic (ROC) curve of 0.911 (95% CI 0.81 to 0.98). This pilot study demonstrates the potential of metabolic biomarkers to assist clinicians in distinguishing bacterial from viral infection in febrile children, to facilitate effective clinical management and to the limit inappropriate use of antibiotics.
Shimizu C, Kim J, Eleftherohorinou H, et al., 2019, HLA-C variants associated with amino acid substitutions in the peptide binding groove influence susceptibility to Kawasaki disease, Human Immunology, Vol: 80, Pages: 731-738, ISSN: 0198-8859
Kawasaki disease (KD) is a pediatric vasculitis caused by an unknown trigger in genetically susceptible children. The incidence varies widely across genetically diverse populations. Several associations with HLA Class I alleles have been reported in single cohort studies. Using a genetic approach, from the nine single nucleotide variants (SNVs) associated with KD susceptibility in children of European descent, we identified SNVs near the HLA-C (rs6906846) and HLA-B genes (rs2254556) whose association was replicated in a Japanese descent cohort (rs6906846 p = 0.01, rs2254556 p = 0.005). The risk allele (A at rs6906846) was also associated with HLA-C*07:02 and HLA-C*04:01 in both US multi-ethnic and Japanese cohorts and HLA-C*12:02 only in the Japanese cohort. The risk A-allele was associated with eight non-conservative amino acid substitutions (amino acid positions); Asp or Ser (9), Arg (14), Ala (49), Ala (73), Ala (90), Arg (97), Phe or Ser (99), and Phe or Ser (116) in the HLA-C peptide binding groove that binds peptides for presentation to cytotoxic T cells (CTL). This raises the possibility of increased affinity to a "KD peptide" that contributes to the vasculitis of KD in genetically susceptible children.
Willems E, Alkema W, Keizer-Garritsen J, et al., 2019, Biosynthetic homeostasis and resilience of the complement system in health and infectious disease, EBioMedicine, Vol: 45, Pages: 303-313, ISSN: 2352-3964
BACKGROUND: The complement system is a central component of the innate immune system. Constitutive biosynthesis of complement proteins is essential for homeostasis. Dysregulation as a consequence of genetic or environmental cues can lead to inflammatory syndromes or increased susceptibility to infection. However, very little is known about steady state levels in children or its kinetics during infection. METHODS: With a newly developed multiplex mass spectrometry-based method we analyzed the levels of 32 complement proteins in healthy individuals and in a group of pediatric patients infected with bacterial or viral pathogens. FINDINGS: In plasma from young infants we found reduced levels of C4BP, ficolin-3, factor B, classical pathway components C1QA, C1QB, C1QC, C1R, and terminal pathway components C5, C8, C9, as compared to healthy adults; whereas the majority of complement regulating (inhibitory) proteins reach adult levels at very young age. Both viral and bacterial infections in children generally lead to a slight overall increase in complement levels, with some exceptions. The kinetics of complement levels during invasive bacterial infections only showed minor changes, except for a significant increase and decrease of CRP and clusterin, respectively. INTERPRETATION: The combination of lower levels of activating and higher levels of regulating complement proteins, would potentially raise the threshold of activation, which might lead to suppressed complement activation in the first phase of life. There is hardly any measurable complement consumption during bacterial or viral infection. Altogether, expression of the complement proteins appears surprisingly stable, which suggests that the system is continuously replenished. FUND: European Union's Horizon 2020, project PERFORM, grant agreement No. 668303.
Borghini L, Png E, Binder A, et al., 2019, Identification of regulatory variants associated with genetic susceptibility to meningococcal disease, Scientific Reports, Vol: 9, ISSN: 2045-2322
Non-coding genetic variants play an important role in driving susceptibility to complex diseases but their characterization remains challenging. Here, we employed a novel approach to interrogate the genetic risk of such polymorphisms in a more systematic way by targeting specific regulatory regions relevant for the phenotype studied. We applied this method to meningococcal disease susceptibility, using the DNA binding pattern of RELA – a NF-kB subunit, master regulator of the response to infection – under bacterial stimuli in nasopharyngeal epithelial cells. We designed a custom panel to cover these RELA binding sites and used it for targeted sequencing in cases and controls. Variant calling and association analysis were performed followed by validation of candidate polymorphisms by genotyping in three independent cohorts. We identified two new polymorphisms, rs4823231 and rs11913168, showing signs of association with meningococcal disease susceptibility. In addition, using our genomic data as well as publicly available resources, we found evidences for these SNPs to have potential regulatory effects on ATXN10 and LIF genes respectively. The variants and related candidate genes are relevant for infectious diseases and may have important contribution for meningococcal disease pathology. Finally, we described a novel genetic association approach that could be applied to other phenotypes.
Menikou S, McArdle A, Kaforou M, et al., 2019, Characterisation of immune complexes in Kawasaki Disease and other infectious diseases by protein sequencing, 103rd Annual Meeting of the American-Association-of-Immunologists, Publisher: AMER ASSOC IMMUNOLOGISTS, ISSN: 0022-1767
Nagelkerke SQ, Tacke CE, Breunis WB, et al., 2019, Extensive ethnic variation and linkage disequilibrium at the FCGR2/3 locus: Different genetic associations revealed in Kawasaki Disease, Frontiers in Immunology, Vol: 10, ISSN: 1664-3224
The human Fc-gamma receptors (FcγRs) link adaptive and innate immunity by binding immunoglobulin G (IgG). All human low-affinity FcγRs are encoded by the FCGR2/3 locus containing functional single nucleotide polymorphisms (SNPs) and gene copy number variants. This locus is notoriously difficult to genotype and high-throughput methods commonly used focus on only a few SNPs. We performed multiplex ligation-dependent probe amplification for all relevant genetic variations at the FCGR2/3 locus in >4,000 individuals to define linkage disequilibrium (LD) and allele frequencies in different populations. Strong LD and extensive ethnic variation in allele frequencies was found across the locus. LD was strongest for the FCGR2C-ORF haplotype (rs759550223+rs76277413), which leads to expression of FcγRIIc. In Europeans, the FCGR2C-ORF haplotype showed strong LD with, among others, rs201218628 (FCGR2A-Q27W, r2 = 0.63). LD between these two variants was weaker (r2 = 0.17) in Africans, whereas the FCGR2C-ORF haplotype was nearly absent in Asians (minor allele frequency <0.005%). The FCGR2C-ORF haplotype and rs1801274 (FCGR2A-H131R) were in weak LD (r2 = 0.08) in Europeans. We evaluated the importance of ethnic variation and LD in Kawasaki Disease (KD), an acute vasculitis in children with increased incidence in Asians. An association of rs1801274 with KD was previously shown in ethnically diverse genome-wide association studies. Now, we show in 1,028 European KD patients that the FCGR2C-ORF haplotype, although nearly absent in Asians, was more strongly associated with susceptibility to KD than rs1801274 in Europeans. Our data illustrate the importance of interpreting findings of association studies concerning the FCGR2/3 locus with knowledge of LD and ethnic variation.
Feinstein Y, Walker JC, Peters MJ, et al., 2018, Cohort profile of the Biomarkers of Acute Serious Illness in Children (BASIC) study: a prospective multicentre cohort study in critically ill children, BMJ Open, Vol: 8, ISSN: 2044-6055
Purpose Despite significant progress, challenges remain in the management of critically ill children, including early identification of infection and organ failure and robust early risk stratification to predict poor outcome. The Biomarkers of Acute Serious Illness in Children study aims to identify genetic and biological pathways underlying the development of critical illness in infections and organ failure and those leading to poor outcome (death or severe disability) in children requiring emergency intensive care.Participants We recruited a prospective cohort of critically ill children undergoing emergency transport to four paediatric intensive care units (PICUs) in Southeast England between April 2014 and December 2016.Findings to date During the study period, 1017 patients were recruited by the regional PICU transport team, and blood and urine samples were obtained at/around first contact with the patient by the transport team. Consent for participation in the study was deferred until after PICU admission and 674 parents/carers were consented. Further samples (blood, urine, stool and throat swabs) were collected after consent. Samples were processed and stored for genomic, transcriptomic, proteomic and metabolomic analyses. Demographic, clinical and laboratory data at first contact, during PICU stay and at discharge, were collected, as were detailed data regarding infectious or non-infectious aetiology. In addition, 115 families have completed 12-month validated follow-up questionnaires to assess quality of life and child behaviour.The first phase of sample analyses (transcriptomic profiling) is currently in progress.Future plans Stored samples will be analysed using genomic, proteomic and metabolic profiling. Advanced bioinformatics techniques will be used to identify biomarkers for early diagnosis of infection, identification of organ failure and risk stratification to predict poor outcome (death/severe disability).Trial registration number NCT03238040.
Wright V, Herberg J, Kaforou M, et al., 2018, Diagnosis of Kawasaki disease using a minimal whole blood gene expression signature, JAMA Pediatrics, Vol: 172, Pages: 1-10, ISSN: 2168-6203
Importance There is no diagnostic test for Kawasaki disease (KD). Diagnosis is based on clinical features shared with other febrile conditions, frequently resulting in delayed or missed treatment and an increased risk of coronary artery aneurysms. Objective To identify a whole blood gene expression signature that distinguishes children with KD in the first week of illness from other febrile conditions.Design Case-control discovery study groups comprising training, test, and validation groups of children with KD or comparator febrile illness. Setting Hospitals in the UK, Spain, Netherlands and USA.Participants The training and test discovery group comprised 404 children with infectious and inflammatory conditions (78 KD, 84 other inflammatory diseases, 242 bacterial or viral infections) and 55 healthy controls. The independent validation group included 130 febrile children and 102 KD patients, including 72 in the first 7 days of illness.Exposures Whole blood gene expression was evaluated using microarrays, and minimal transcript sets distinguishing KD were identified using a novel variable selection method (Parallel Deterministic Model Search).Main outcomes and measures The ability of transcript signatures - implemented as Disease Risk Scores - to discriminate KD cases from controls, was assessed by Area Under the Curve (AUC), sensitivity, and specificity at the optimal cut-point according to Youden’s index. Results A 13-transcript signature identified in the discovery training set distinguished KD from other infectious and inflammatory conditions in the discovery test set with AUC, sensitivity, and specificity (95% confidence intervals (CI)) of 96.2% (92.5-99.9), 81.7% (60.0-94.8), and 92.1% (84.0-97.0), respectively. In the validation set, the signature distinguished KD from febrile controls with AUC, sensitivity, and specificity (95% CI) of 94.6% (91.3-98.0), 85.9% (76.8-92.6), and 89.1% (83.0-93.7) respectively. The signature was applied to clinically defin
Martinón-Torres F, Salas A, Rivero-Calle I, et al., 2018, Life-threatening infections in children in Europe (the EUCLIDS Project): a prospective cohort study, Lancet Child and Adolescent Health, Vol: 2, Pages: 404-414, ISSN: 2352-4642
Background: Sepsis and severe focal infections represent a substantial disease burden in children admitted to hospital. We aimed to understand the burden of disease and outcomes in children with life-threatening bacterial infections in Europe. Methods: The European Union Childhood Life-threatening Infectious Disease Study (EUCLIDS) was a prospective, multicentre, cohort study done in six countries in Europe. Patients aged 1 month to 18 years with sepsis (or suspected sepsis) or severe focal infections, admitted to 98 participating hospitals in the UK, Austria, Germany, Lithuania, Spain, and the Netherlands were prospectively recruited between July 1, 2012, and Dec 31, 2015. To assess disease burden and outcomes, we collected demographic and clinical data using a secured web-based platform and obtained microbiological data using locally available clinical diagnostic procedures. Findings: 2844 patients were recruited and included in the analysis. 1512 (53·2%) of 2841 patients were male and median age was 39·1 months (IQR 12·4–93·9). 1229 (43·2%) patients had sepsis and 1615 (56·8%) had severe focal infections. Patients diagnosed with sepsis had a median age of 27·6 months (IQR 9·0–80·2), whereas those diagnosed with severe focal infections had a median age of 46·5 months (15·8–100·4; p < 0·0001). Of 2844 patients in the entire cohort, the main clinical syndromes were pneumonia (511 [18·0%] patients), CNS infection (469 [16·5%] ), and skin and soft tissue infection (247 [8·7%]). The causal microorganism was identified in 1359 (47·8%) children, with the most prevalent ones being Neisseria meningitidis (in 259 [9·1%] patients), followed by Staphylococcus aureus (in 222 [7·8%]), Streptococcus pneumoniae (in 219 [7·7%] ), and group A streptococcus (in 162 [5·7%]). 1070 (37·6%) patients required admis
Mashbat B, Bellos E, Bidmos F, et al., 2018, Whole exome sequencing identifies BPIFA1 mutation underlying invasive meningococcal disease, Human Genome Meeting 2018, Publisher: BIOMED CENTRAL LTD, ISSN: 1473-9542
Bellos E, Herberg J, Wright V, et al., 2018, The genetic basis of invasive meningococcal disease revealed thorough whole exome sequencing, Human Genome Meeting 2018, Publisher: BioMed Central, ISSN: 1479-7364
BackgroundInvasive meningococcal disease (IMD) is a rare condition affectingchildren and young adults due to infection with Neisseria meningitidis, resulting in meningitis or sepsis. Although the majority of thegeneral population is colonized by N. meningitidis, only a small minority go on to develop IMD, suggesting that those that succumb toinvasive disease may possess an underlying genetic susceptibility.The notion of a genetic contribution to disease manifestation is supported by the finding that patients with congenital complement deficiencies are susceptible to recurrent IMD, yet these conditions arerare. With the aim of identifying other genetic factors underlying IMD, we carried out whole exome sequencing (WES) of approximately 300 IMD patients from an extensive and well characterizedcohort of >2,000 childhood IMD patients.Materials and MethodsThe WES analysis focused on rare variants (MAF<0.01) predicted tohave a detrimental effect on protein function. We undertook analysisof seven multiplex families identifying IBD variants. The rest of theindex cases were analysed as a cohort and put through gene andpathway burden tests to identify any genes/pathways that wereenriched in the collection of patients.ResultsThese analyses revealed a number of patients harbouring mutationsin known primary immunodeficiency genes (approx. 10%) as well asa novel configuration of mutations underlying the complementgenes. Furthermore, novel mutations in the coagulation pathway andmucosal immunity genes were identified and functionally confirmed.ConclusionsThe identification of genes involved in IMD through WES has demonstrated the complex genetic architecture of meningococcal immunityrevealed some novel and unexpected genes/pathways that modulatedisease susceptibility and severity. The results from this studyprovide us with a more comprehensive understanding of IMDpathogenesis.
von Both U, Berk M, Agapow P-M, et al., 2018, Mycobacterium tuberculosis Exploits a Molecular Off Switch of the Immune System for Intracellular Survival, Scientific Reports, Vol: 8, ISSN: 2045-2322
Mycobacterium tuberculosis (M. tuberculosis) survives and multiplies inside human macrophages by subversion of immune mechanisms. Although these immune evasion strategies are well characterised functionally, the underlying molecular mechanisms are poorly understood. Here we show that during infection of human whole blood with M. tuberculosis, host gene transcriptional suppression, rather than activation, is the predominant response. Spatial, temporal and functional characterisation of repressed genes revealed their involvement in pathogen sensing and phagocytosis, degradation within the phagolysosome and antigen processing and presentation. To identify mechanisms underlying suppression of multiple immune genes we undertook epigenetic analyses. We identified significantly differentially expressed microRNAs with known targets in suppressed genes. In addition, after searching regions upstream of the start of transcription of suppressed genes for common sequence motifs, we discovered novel enriched composite sequence patterns, which corresponded to Alu repeat elements, transposable elements known to have wide ranging influences on gene expression. Our findings suggest that to survive within infected cells, mycobacteria exploit a complex immune “molecular off switch” controlled by both microRNAs and Alu regulatory elements.
Hemingway C, Berk M, Anderson ST, et al., 2017, Childhood tuberculosis is associated with decreased abundance of T cell gene transcripts and impaired T cell function., PLoS ONE, Vol: 12, ISSN: 1932-6203
The WHO estimates around a million children contract tuberculosis (TB) annually with over 80 000 deaths from dissemination of infection outside of the lungs. The insidious onset and association with skin test anergy suggests failure of the immune system to both recognise and respond to infection. To understand the immune mechanisms, we studied genome-wide whole blood RNA expression in children with TB meningitis (TBM). Findings were validated in a second cohort of children with TBM and pulmonary TB (PTB), and functional T-cell responses studied in a third cohort of children with TBM, other extrapulmonary TB (EPTB) and PTB. The predominant RNA transcriptional response in children with TBM was decreased abundance of multiple genes, with 140/204 (68%) of all differentially regulated genes showing reduced abundance compared to healthy controls. Findings were validated in a second cohort with concordance of the direction of differential expression in both TBM (r2 = 0.78 p = 2x10-16) and PTB patients (r2 = 0.71 p = 2x10-16) when compared to a second group of healthy controls. Although the direction of expression of these significant genes was similar in the PTB patients, the magnitude of differential transcript abundance was less in PTB than in TBM. The majority of genes were involved in activation of leucocytes (p = 2.67E-11) and T-cell receptor signalling (p = 6.56E-07). Less abundant gene expression in immune cells was associated with a functional defect in T-cell proliferation that recovered after full TB treatment (p<0.0003). Multiple genes involved in T-cell activation show decreased abundance in children with acute TB, who also have impaired functional T-cell responses. Our data suggest that childhood TB is associated with an acquired immune defect, potentially resulting in failure to contain the pathogen. Elucidation of the mechanism causing the immune paresis may identify new treatment and prevention strategies.
Shimizu C, Kim J, Eleftherohorinou H, et al., 2017, Genetic Variants in HLA-C and Class I Pathway Genes Influence Susceptibility to Kawasaki Disease, 2017 ACR/ARHP Annual Meeting, Publisher: Wiley, ISSN: 2326-5205
Kaforou M, Herberg JA, Wright VJ, et al., 2017, Diagnosis of bacterial infection using a 2-transcript host RNA signature in febrile infants 60 days or younger, JAMA: Journal of the American Medical Association, Vol: 317, Pages: 1577-1578, ISSN: 0098-7484
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