Identification of bacterial pathogens in sudden unexpected death in infancy and childhood using 16S rRNA gene sequencing.

Background: Sudden unexpected death in infancy (SUDI) is the most common cause of post-neonatal death in the developed world. Following an extensive investigation, the cause of ~40% of deaths remains unknown. It is hypothesized that a proportion of deaths are due to an infection that remains undetected due to limitations in routine techniques. This study aimed to apply 16S rRNA gene sequencing to post-mortem (PM) tissues collected from cases of SUDI, as well as those from the childhood equivalent (collectively known as sudden unexpected death in infancy and childhood or SUDIC), to investigate whether this molecular approach could help identify potential infection-causing bacteria to enhance the diagnosis of infection. Methods: In this study, 16S rRNA gene sequencing was applied to de-identified frozen post-mortem (PM) tissues from the diagnostic archive of Great Ormond Street Hospital. The cases were grouped depending on the cause of death: (i) explained non-infectious, (ii) infectious, and (iii) unknown. Results and conclusions: In the cases of known bacterial infection, the likely causative pathogen was identified in 3/5 cases using bacterial culture at PM compared to 5/5 cases using 16S rRNA gene sequencing. Where a bacterial infection was identified at routine investigation, the same organism was identified by 16S rRNA gene sequencing. Using these findings, we defined criteria based on sequencing reads and alpha diversity to identify PM tissues with likely infection. Using these criteria, 4/20 (20%) cases of unexplained SUDIC were identified which may be due to bacterial infection that was previously undetected. This study demonstrates the potential feasibility and effectiveness of 16S rRNA gene sequencing in PM tissue investigation to improve the diagnosis of infection, potentially reducing the number of unexplained deaths and improving the understanding of the mechanisms involved.

Early ART-initiation and longer ART duration reduces HIV-1 proviral DNA levels in children from the CHER trial.

BACKGROUND: Reduction of the reservoir of latent HIV-infected cells might increase the possibility of long-term remission in individuals living with HIV. We investigated factors associated with HIV-1 proviral DNA levels in children receiving different antiretroviral therapy (ART) strategies in the children with HIV early antiretroviral therapy (CHER) trial. METHODS: Infants with HIV < 12 weeks old with CD4% ≥ 25% were randomized in the CHER trial to early limited ART for 40 or 96 weeks (ART-40 W, ART-96 W), or deferred ART (ART-Def). For ART-Def infants or following ART interruption in ART-40 W/ART-96 W, ART was started/re-started for clinical progression or CD4% < 25%. In 229 participants, HIV-1 proviral DNA was quantified by PCR from stored peripheral blood mononuclear cells from children who had received ≥ 24 weeks ART and two consecutive undetectable HIV-1 RNA 12-24 weeks apart. HIV-1 proviral DNA was compared between ART-Def and ART-96 W at week 96, and in all arms at week 248. Factors associated with HIV-1 proviral DNA levels were evaluated using linear regression. FINDINGS: Longer duration of ART was significantly associated with lower HIV-1 proviral DNA at both 96 (p = 0.0003) and 248 weeks (p = 0.0011). Higher total CD8 count at ART initiation was associated with lower HIV-1 proviral DNA at both 96 (p = 0.0225) and 248 weeks (p = 0.0398). Week 248 HIV-1 proviral DNA was significantly higher in those with positive HIV-1 serology at week 84 than those with negative serology (p = 0.0042). INTEPRETATION: Longer ART duration is key to HIV-1 proviral DNA reduction. Further understanding is needed of the effects of "immune-attenuation" through early HIV-1 exposure. FUNDING: Wellcome Trust, National Institutes of Health, Medical Research Council.

Characterising Post-mortem Bacterial Translocation Under Clinical Conditions Using 16S rRNA Gene Sequencing in Two Animal Models.

Sudden unexpected death in infancy (SUDI) is the sudden and unexpected death of an apparently healthy infant occurring within the first year of life where the cause is not immediately obvious. It is believed that a proportion of unexplained infant deaths are due to an infection that remains undiagnosed. The interpretation of post-mortem microbiology results is difficult due to the potential false-positives, a source of which is post-mortem bacterial translocation. Post-mortem bacterial translocation is the spread of viable bacteria from highly colonised sites to extra-intestinal tissues. We hypothesise that although post-mortem bacterial translocation occurs, when carcasses are kept under controlled routine clinical conditions it is not extensive and can be defined using 16S rRNA gene sequencing. With this knowledge, implementation of the 16S rRNA gene sequencing technique into routine clinical diagnostics would allow a more reliable retrospective diagnosis of ante-mortem infection. Therefore, the aim of this study was to establish the extent of post-mortem bacterial translocation in two animal models to establish a baseline sequencing signal for the post-mortem process. To do this we used 16S rRNA gene sequencing in two animal models over a 2 week period to investigate (1) the bacterial community succession in regions of high bacterial colonisation, and (2) the bacterial presence in visceral tissues routinely sampled during autopsy for microbiological investigation. We found no evidence for significant and consistent post-mortem bacterial translocation in the mouse model. Although bacteria were detected in tissues in the piglet model, we did not find significant and consistent evidence for post-mortem bacterial translocation from the gastrointestinal tract or nasal cavity. These data do not support the concept of significant post-mortem translocation as part of the normal post-mortem process.

Minimal change in structural, functional and inflammatory markers of lung disease in newborn screened infants with cystic fibrosis at one year.

BACKGROUND: With the widespread introduction of newborn screening for cystic fibrosis (CF), there has been considerable emphasis on the need to develop objective markers of lung health that can be used during infancy. We hypothesised that in a newborn screened (NBS) UK cohort, evidence of airway inflammation and infection at one year would be associated with adverse structural and functional outcomes at the same age. METHODS: Infants underwent lung function testing, chest CT scan and bronchoscopy with bronchoalveolar lavage (BAL) at 1 year of age when clinically well. Microbiology cultures were also available from routine cough swabs. RESULTS: 65 infants had lung function, CT and BAL. Mean (SD) lung clearance index and forced expiratory volume in 0.5 s z-scores were 0.9(1.2) and -0.6(1.1) respectively; median Brody II CF-CT air trapping score on chest CT =0 (interquartile range 0-1, maximum possible score 27). Infants isolating any significant pathogen by 1 yr of age had higher LCI z-score (mean difference 0.9; 95%CI:0.4-1.4; p = 0.001) and a trend towards higher air trapping scores on CT (p = 0.06). BAL neutrophil elastase was detectable in 23% (10/43) infants in whom BAL supernatant was available. This did not relate to air trapping score on CT. CONCLUSIONS: In this UK NBS cohort at one year of age, lung and airway damage is much milder and associations between inflammation, abnormal physiology and structural changes were at best weak, contrary to our hypothesis and previously published reports. Continued follow-up will clarify longer term implications of these very mild structural, functional and inflammatory changes.

Specific Immunity to Cytomegalovirus in Pediatric Cardiac Transplantation.

BACKGROUND: Cytomegalovirus (CMV) infection is implicated in endothelial dysfunction and graft damage after pediatric heart transplantation. CMV-specific immune responses are thought to be necessary for CMV viral control but there is little data in pediatric heart transplantation. METHODS: We studied 28 consecutive pediatric heart transplant recipients for 1 year posttransplant. CMV T-cell expressing IFN-γ, TNF-α, and IL-2 in response to ex vivo stimulation with CMV lysates or peptides were measured. Circulating cytokines were measured in plasma. Generalized Additive Models were applied to the data to model changes of cell population dynamics over time. RESULTS: CMV-specific T cell-mediated responses were impaired in the first 8 weeks posttransplant. During this period, 25% of patients had CMV viremia, of which those with VLs of 10 000 or more CMV deoxyribonucleic acid copies/mL were given ganciclovir. In this group, the frequency of CD4+ and CD8+ T cells producing IFN-γ and the CD8+CD57+ granzyme B+ T-cell population increased at 12 to 24 weeks and remained elevated for the duration of the study. CONCLUSIONS: We have shown that CMV viremia is associated with CMV-specific immune responses and increased CD8+CD57+ granzyme B+ cells at 1 year posttransplant; however, early responses were not predictive of impending CMV viremia. It remains to be seen if the early CMV immune response detected is associated with endothelial and allograft damage, in light of previous studies demonstrating increased vasculopathy in pediatric patients with CMV viremia.

Modelling CD4 T Cell Recovery in Hepatitis C and HIV Co-infected Children Receiving Antiretroviral Therapy.

BACKGROUND: The effect of hepatitis C virus (HCV) coinfection on CD4 T cell recovery in treated HIV-infected children is poorly understood. OBJECTIVE: To compare CD4 T cell recovery in HIV/HCV coinfected children with recovery in HIV monoinfected children. METHOD: We studied 355 HIV monoinfected and 46 HIV/HCV coinfected children receiving antiretroviral therapy (ART) during a median follow-up period of 4.2 years (interquartile range: 2.7-5.3 years). Our dataset came from the Ukraine pediatric HIV Cohort and the HIV/HCV coinfection study within the European Pregnancy and Paediatric HIV Cohort Collaboration. We fitted an asymptotic nonlinear mixed-effects model of CD4 T cell reconstitution to age-standardized CD4 counts in all 401 children and investigated factors predicting the speed and extent of recovery. RESULTS: We found no significant impact of HCV coinfection on either pre-ART or long-term age-adjusted CD4 counts (z scores). However, the rate of increase in CD4 z score was slower in HIV/HCV coinfected children when compared with their monoinfected counterparts (P < 0.001). Both monoinfected and coinfected children starting ART at younger ages had higher pre-ART (P < 0.001) and long-term (P < 0.001) CD4 z scores than those who started when they were older. CONCLUSIONS: HIV/HCV coinfected children receiving ART had slower CD4 T cell recovery than HIV monoinfected children. HIV/HCV coinfection had no impact on pre-ART or long-term CD4 z scores. Early treatment of HIV/HCV coinfected children with ART should be encouraged.

Haemodynamic changes with paracetamol in critically-ill children.

PURPOSE: Paracetamol has been associated with a reduction in blood pressure, especially in febrile, critically-ill adults. We hypothesised that blood pressure would fall following administration of paracetamol in critically-ill children and this effect would be greater during fever and among children with a high body surface area to weight ratio. METHODS: A 12-month prospective observational study of children (0-16years) admitted to paediatric intensive care, who underwent pulse contour analysis and received paracetamol concurrently. RESULTS: Mean arterial blood pressure decreased significantly by 4.7% from baseline (95% CI 1.75-8.07%) in 31 children following 148 doses of paracetamol. The nadir was 2-hour post-dose. The effect was pronounced in children with fever at baseline (6.4%, 95% CI 2.8-10%), although this was not statistically significant. There was no simple relationship between this effect and body surface area to weight ratio. The association between a change in blood pressure and changes in heart rate or measured stroke volume was poor; therefore it was likely that a change in the systemic vascular resistance contributes most to this effect. CONCLUSION: There is a significant but modest reduction in blood pressure post-paracetamol in critically-ill children. This is likely related to a change in systemic vascular resistance.

Deficiency of Adenosine Deaminase Type 2: A Description of Phenotype and Genotype in Fifteen Cases.

OBJECTIVE: To describe the clinical features, genotype, and treatment in a series of subjects with confirmed adenosine deaminase 2 (ADA2) deficiency. METHODS: All symptomatic subjects were referred for genetic testing for suspected ADA2 deficiency; relatives of index cases were also screened. Demographic, clinical, and laboratory characteristics and treatments were recorded. Genetic analyses included whole-exome sequencing in 4 subjects and Sanger sequencing of CECR1 (the gene for cat eye syndrome chromosome region candidate 1) in all subjects. Assays for ADA2 enzyme activity and quantitative polymerase chain reaction analysis of CECR1 messenger RNA (mRNA) were also performed. RESULTS: We identified 15 subjects with ADA2 deficiency, 5 of whom were asymptomatic (relatives of index cases; ages 5-42 years). Homozygous or compound heterozygous mutations in CECR1 were identified in all subjects. Phenotypic manifestations in the patients with symptomatic ADA2 deficiency included livedo racemosa (73.3%), neurologic involvement (53.3%), and immunodeficiency (46.7%). CECR1 mRNA expression in 8 subjects, including 5 who were presymptomatic, was significantly lower than in healthy controls (P = 0.0016). Subjects with ADA2 deficiency (with or without symptoms) also had lower ADA2 enzyme activity compared to healthy pediatric controls (P < 0.0001) and patients with sporadic (nonfamilial) childhood polyarteritis nodosa (PAN) without CECR1 mutation (P = 0.0108). Anti-tumor necrosis factor therapy was required in 9 of the 10 symptomatic subjects. CONCLUSION: The clinical manifestations of ADA2 deficiency ranged in severity from limited cutaneous involvement to severe multisystemic vasculitis; one-third of our cases (5 of 15) were currently asymptomatic, and required close monitoring. We recommend CECR1 screening for unaffected siblings of index cases, cases of familial vasculitis, and cases of PAN that is resistant to standard treatment.

B-cell development and pneumococcal immunity in vertically acquired HIV infection.

OBJECTIVES: Many children with HIV infection now survive into adulthood. This study explored the impact of vertically acquired HIV in the era of antiretroviral therapy on the development of humoral immunity. DESIGN: Natural and vaccine-related immunity to pneumococcus and B-cell phenotype was characterized and compared in three groups of young adults: those with vertically-acquired infection, those with horizontally acquired infection and healthy controls. METHODS: Serotype-specific pneumococcal (Pnc) immunoglobulin M and G concentrations before and up to 1 year post-Pnc polysaccharide (Pneumovax) immunization were determined, and opsonophagocytic activity was analysed. B-cell subpopulations and dynamic markers of B-cell signalling, turnover and susceptibility to apoptosis were evaluated by flow cytometry. RESULTS: HIV-infected patients showed impaired natural Pnc immunity and reduced humoral responses to immunization with Pneumovax; this was greatest in those viraemic at time of the study. Early-life viral control before the age of 10 years diminished these changes. Expanded populations of abnormally activated and immature B-cells were seen in both HIV-infected cohorts. Vertically infected patients were particularly vulnerable to reductions in marginal zone and switched memory populations. These aberrations were reduced in patients with early-life viral control. CONCLUSION: In children with HIV, damage to B-cell memory populations and impaired natural and vaccine immunity to pneumococcus is evident in early adult life. Sustained viral control from early childhood may help to limit this effect and optimize humoral immunity in adult life.

Paediatric Behçet's disease: a UK tertiary centre experience.

There are currently limited data regarding paediatric Behçet's disease (BD), particularly in the UK. We describe the clinical spectrum, treatment and outcome of BD, and explore the relative sensitivities of the criteria for the diagnosis of BD in a UK paediatric cohort. Single retrospective case note review of children with a clinical diagnosis of BD presenting between 1987 and 2012. Demographics, clinical features, treatment and outcomes were recorded. The sensitivities of the International Study Group (ISG) and International Criteria for BD (ICBD) criteria were explored. BD disease activity was calculated using the Behçet's Disease Activity Index (BDAI). Forty-six patients (22 male) were identified. Median age of onset was 4.87 (0.04-15.71) years; median time to diagnosis was 3.74 (0.25-13.48) years. Clinical features were recurrent oral ulceration (97.8 %), recurrent genital ulceration (73.9 %), gastrointestinal (58.7 %), musculoskeletal (47.83 %), cutaneous (23.9 %) involvement and uveitis (2 %). Recurrent genital ulceration was more common in female patients (P = 0.044). Thirty-seven patients (80.4 %) fulfilled the ICBD criteria; only 12 patients (26.1 %) fulfilled the ISG criteria. BDAI score at diagnosis was 7/20 (0-10/20) and significantly decreased to 5/20 (0-9/20) (P < 0.0001) at latest follow-up. The commonest systemic treatment was colchicine (76.1 %); anti-TNFα treatment was reserved for severe cases (15.5 %). Paediatric BD in the UK may present very early in life, sometimes with a family history, and with a low incidence of ocular involvement. Diagnostic delay is common. The majority of our patients required systemic therapy; anti-TNFα was reserved for severe cases and has largely superseded the use of thalidomide.

Impaired function of endothelial progenitor cells in children with primary systemic vasculitis.

INTRODUCTION: Previously, we demonstrated that children with active systemic vasculitis (SV) have higher circulating CD34 + CD133 + KDR+ endothelial progenitor cells (EPC); the function of these EPCs, and their relationship with disease activity in vasculitis remains largely unexplored. We hypothesized that although EPC numbers are higher, EPC function is impaired in active SV of the young. The aims of this study were therefore to: 1. investigate the relationship between disease activity and EPC function in children with SV; and 2. study the influence of systemic inflammation on EPC function by investigating the effects of hyperthermia and TNF-α on EPC function. METHODS: We performed a cross-sectional study of unselected children with SV with different levels of disease activity attending a single center (Great Ormond Street Hospital, London) between October 2008 and December 2014. EPCs were isolated from peripheral blood of children with SV, and healthy child controls. EPC function was assessed by their potential to form colonies (EPC-CFU), and ability to form clusters and incorporate into human umbilical vein endothelial cell (HUVEC) vascular structures in matrigel. The effects of hyperthermia and TNF-α on EPC function were also studied. RESULTS: Twenty children, median age 12-years (5-16.5; nine males) were studied. EPC-CFU and the number of EPC clusters formed on matrigel were significantly reduced in children with active vasculitis compared with healthy controls (p = 0.02 for EPC-CFU; p = 0.01 for EPC cluster formation). Those with active vasculitis had lower EPC-CFU and EPC cluster formation than those with inactive disease, although non-significantly so. In addition, EPC incorporation into matrigel HUVEC networks was lower in children with SV compared with healthy children, irrespective of disease activity. Ex-vivo pre-treatment of EPC with hyperthermia impaired EPC function; TNF-α down-regulated EPC expression of CD18/CD11b and resulted in decreased incorporation into HUVEC networks. CONCLUSIONS: Whilst our previous work showed that circulating CD34 + EPC numbers are well preserved, this study revealed that EPC function is significantly impaired in children with vasculitis. It is possible that the chronic inflammatory milieu associated with vasculitis may impair EPC function, and thus contribute to an unfavourable balance between endothelial injury and repair. The mechanism of this remains to be established, however.

Association between maternal dental periapical infections and pregnancy outcomes: results from a cross-sectional study in Malawi.

OBJECTIVES: Maternal infections are associated with intrauterine growth restriction (IUGR) and preterm birth (PTB). Dental infections are common in low-income settings, but their contribution to adverse pregnancy outcomes is unknown. We studied the epidemiology of dental periapical infections among pregnant women and their association to foetal growth restriction and the duration of pregnancy in a rural sub-Saharan African population. METHODS: This was a cross-sectional study on the association between maternal dental periapical infections and birth outcomes, in Malawi, Africa. We assessed oral health clinically and radiologically among recently delivered women with known duration of pregnancy and measured birthweight (BW), length and head circumference of their infants. RESULTS: Of 1024 analysed participants, 23.5% had periapical infections. Mean duration of pregnancy was 39.4 weeks, BW 2979 g and length 49.7 cm. Women with periapical infection had mean (95% CI) pregnancy duration 0.4 weeks (0.1-0.8) shorter and delivered infants with 79 g (13-145) lower BW and 0.5 cm (0.2-0.9) shorter neonatal length than women without periapical infection. The incidence of PTB was 10.0% among women with periapical infection and 7.3% among those without (adjusted difference 3.5%, 95% CI -1.1-8.1%). Corresponding prevalences for stunting were 20.9% and 14.2% (adjusted difference 9.0%, 95% CI 2.7%-15.2%). The population-attributable risk fraction attributable to periapical infection was 9.7% for PTB and 12.8% for stunting. CONCLUSIONS: Periapical infection was associated with shorter pregnancy duration and IUGR in the study area; interventions addressing this risk factor may improve birth outcomes in low-income settings.

Endothelial Repair in Childhood Arterial Ischaemic Stroke with Cerebral Arteriopathy.

BACKGROUND: We have previously shown that recurrent arterial ischaemic stroke (AIS) in children with cerebral arteriopathy is associated with increased circulating endothelial cells and endothelial microparticles, consistent with ongoing endothelial injury. To date, however, little is known about endothelial repair responses in childhood AIS. We examined the relationship between the number and function of circulating endothelial progenitor cells (EPC), the levels of brain-derived neurotrophic factor (BDNF) and AIS recurrence. METHODS: Flow cytometry was used to identify peripheral blood mononuclear cells positive for CD34/kinase insert domain-containing receptor (KDR). In a subgroup of patients (5 in each group selected at random), monocytic EPC function was assessed by colony-forming unit (EPC-CFU) capacity and incorporation into endothelial cell networks in Matrigel. BDNF was measured using ELISA. RESULTS: Thirty-five children, aged 12 years (range: 5-16.5; 9 males), with AIS and cerebral arteriopathy were studied; 10 had recurrent AIS. CD34+/KDR+ cells were significantly higher in recurrent AIS compared to non-recurrent AIS patients (p = 0.005) and controls (p = 0.0002). EPC-CFU and EPC incorporation into endothelial cell networks were significantly reduced in recurrent compared to non-recurrent AIS patients (p = 0.04 and p = 0.01, respectively). Levels of BDNF were significantly higher in recurrent compared to non-recurrent AIS patients (p = 0.0008) and controls (p = 0.0002). CONCLUSIONS: Children with recurrent AIS and cerebral arteriopathy had increased circulating CD34+/KDR+ cells and BDNF consistent with an endothelial repair response. However, EPC function was impaired. Future studies are needed to examine whether suboptimal endothelial repair contributes to childhood AIS recurrence.

Reactivity of routine HIV antibody tests in children who initiated antiretroviral therapy in early infancy as part of the Children with HIV Early Antiretroviral Therapy (CHER) trial: a retrospective analysis.

BACKGROUND: Early antiretroviral therapy (ART) and virological suppression can affect evolving antibody responses to HIV infection. We aimed to assess frequency and predictors of seronegativity in infants starting early ART. METHODS: We compared HIV antibody results between two of three treatment groups of the Children with HIV Early Antiretroviral Therapy (CHER) trial, done from July, 2005, until July, 2011, in which infants with HIV infection aged 5·7-12·0 weeks with a percentage of CD4-positive T lymphocytes of at least 25% were randomly assigned to immediate ART for 96 weeks (ART-96W) or deferred ART until clinical or immunological progression (ART-Def). We measured antibody from all available stored samples for ART-96W and ART-Def at trial week 84 using three assays: fourth-generation enzyme immunoassay HIV antigen-antibody combination, HIV-1 and HIV-2 rapid antibody test, and quantitative anti-gp120 IgG ELISA. We also assessed odds of seropositivity with respect to age of ART initiation and cumulative viral load. The CHER trial was registered with ClinicalTrials.gov, number NCT00102960. FINDINGS: The median age of the infants from when samples were taken (184 samples from 268 infants) was 92 weeks (IQR 90·6-93·4). More specimens from the ART-96W group were seronegative than from the ART-Def group by enzyme immunoassay (ART-96W 49 [46%] of 107 vs ART-Def eight [11%] of 75; p<0·0001) and rapid antibody test (54 [53%] of 101 vs eight [11%] of 74; p<0·0001). Median anti-gp120 IgG concentration was lower in the ART-96W group (230 µg/µL [IQR 133-13 129]) than in the ART-Def group (6870 µg/µL [1706-53 645]; p<0·0001). If ART was started between 12 and 24 weeks of age, odds of seropositivity were increased 13·7 times (95% CI 3·1-60·2; p=0·001) compared with starting it between 0 and 12 weeks. All children starting ART aged older than 24 weeks were seropositive. Cumulative viral load to week 84 correlated with anti-gp120 IgG concentrations (coefficient 0·54; p<0·0001) and increased odds of seropositivity (odds ratio 1·59 [95% CI 1·1-2·3]) adjusted for ART initiation age. INTERPRETATION: About half of children starting ART before 12 weeks of age were HIV seronegative by almost 2 years of age. HIV antibody tests cannot be used to reconfirm HIV diagnosis in children starting early ART. Long-term effects of seronegativity need further study. Clear guidelines are needed for retesting alongside improved diagnostic tests. FUNDING: Wellcome Trust, Medical Research Council, and National Institutes of Health.

Using CD4 percentage and age to optimize pediatric antiretroviral therapy initiation.

BACKGROUND: Quantifying pediatric immunologic recovery by highly active antiretroviral therapy (HAART) initiation at different CD4 percentage (CD4%) and age thresholds may inform decisions about timing of treatment initiation. METHODS: HIV-1-infected, HAART-naive children in Europe and the Americas were followed from 2002 through 2009 in PENPACT-1. Data from 162 vertically infected children, with at least World Health Organization "mild" immunosuppression and CD4% <10th percentile, were analyzed for improvement to a normal CD4% (≥10th percentile) within 4 years after HAART initiation. Data from 209 vertically infected children, regardless of immune status, were analyzed for CD4% outcomes at 4 years and viral failure within 4 years. RESULTS: Seventy-two percent of baseline immunosuppressed children recovered to normal within 4 years. Compared with "severe" immunosuppression, more children with "mild" immunosuppression (difference 36%, 95% confidence interval [CI]: 22% to 49%) or "advanced" immunosuppression (difference 20.8%, 95% CI: 5.8% to 35.9%) recovered a normal CD4%. For each 5-year increase in baseline age, the proportion of children achieving a normal CD4% declined by 19% (95% CI: 11% to 27%). Combining baseline CD4% and age effects resulted in >90% recovery when initiating HAART with "mild" immunosuppression at any age or "advanced" immunosuppression at age <3 years. Baseline CD4% effects became greater with increasing age (P = .02). At 4 years, most immunologic benefits were still significant but diminished. Viral failure was highest in infancy (56%) and adolescence (63%). CONCLUSIONS: Initiating HAART at higher CD4% and younger ages maximizes potential for immunologic recovery. Guidelines should weigh immunologic benefits against long-term risks.

Systemic polyarteritis nodosa in the young: a single-center experience over thirty-two years.

OBJECTIVE: Polyarteritis nodosa (PAN) is a rare disease of childhood. The aims of this study were to describe the clinical features, treatment, and outcome of systemic childhood PAN and to identify predictors of relapse. METHODS: A single-center retrospective medical records review of children with PAN fulfilling the European League Against Rheumatism (EULAR)/Paediatric Rheumatology European Society (PRES)/Paediatric Rheumatology International Trials Organisation (PRINTO) classification criteria who were seen over a 32-year period was performed. Data on demographic and clinical features, treatments, relapses (recurrence of clinical signs/symptoms or occurrence of new symptoms after initial remission requiring escalation or resumption of immunosuppressive therapy), and deaths were recorded. A disease activity score was retrospectively assigned using the Paediatric Vasculitis Activity Score (PVAS) instrument. Cox regression analysis was used to identify significant predictors of relapse. RESULTS: Sixty-nine children with PAN were identified; 55% were male, and their median age was 8.5 years (range 0.9-15.8 years). Their clinical features at presentation were fever (87%), myalgia (83%), skin (88%), renal (19%), severe gastrointestinal (GI) (10%), and neurologic (10%) involvement. The PVAS at presentation was 9 of 63 (range 4-24). Histopathologic analysis of the skin showed necrotizing vasculitis in biopsy samples from 40 of 50 children. Results of selective visceral arteriography suggested the presence of PAN in 96% of patients. Treatment included cyclophosphamide and corticosteroids (83%), plasma exchange (9%), and biologic agents (after 2002; 13%). The relapse rate was 35%, and the mortality rate was 4%. Severe GI involvement was associated with increased risk of relapse (P = 0.031), while longer time to induce remission (P = 0.022) and increased cumulative dose of cyclophosphamide (P = 0.005) were associated with lower relapse risk. CONCLUSION: Childhood PAN is a severe inflammatory disease of insidious onset and variable clinical presentation. Relapses occurred more frequently in those with severe GI involvement. A higher cumulative dose of cyclophosphamide was associated with a lower risk of relapse.

Mannose-binding lectin genotype influences frequency and duration of infectious complications in children with malignancy.

Children with cancer receiving identical treatment differ in their experience of infection, suggesting that variations in immunity may influence susceptibility to infection. Studies of the influence of mannose-binding lectin (MBL), an important component of the innate immune system, in children with febrile neutropenia (FN) have yielded conflicting results. We examined the role of MBL in infection susceptibility in the largest cohort of children with cancer reported to date. MBL levels were measured and genotyping performed on children (≤16 y) receiving chemotherapy for cancer in London, UK. Clinical data from FN episodes were recorded prospectively. MBL status was assessed in 269 children; 513 episodes of FN were captured from 211 patients. Patients with MBL2 polymorphisms experienced more FN episodes than wildtype genotype (median 2 vs. 1, respectively; P = 0.074) and more episodes with documented infection (P = 0.045). Patients experiencing multiple FN episodes had lower MBL levels (P = 0.036). MBL genotype influenced duration of episode in some groups: high-risk MBL-deficient patients spent up to 5 nights longer/episode in hospital than equivalent wildtypes. These results indicate that MBL deficiency influences both susceptibility to and outcome of FN episodes and may be most important in those patients at higher risk of complications of FN.

Endothelial injury in childhood stroke with cerebral arteriopathy: a cross-sectional study.

OBJECTIVE: Circulating endothelial cells (CECs) and microparticles (MPs) have been reported to reflect endothelial injury, cellular activation, and MP-mediated thrombin generation. We tested the hypothesis that these indices differ between children with cerebral arteriopathy and arterial ischemic stroke (AIS) recurrence, and those with a single event. METHODS: This was a single-center cross-sectional study of 46 children with AIS and cerebral arteriopathy matched with pediatric controls. AIS recurrence was defined as new acute neurologic deficit with radiologic evidence of further cerebral infarction. CECs and MPs were identified with immunomagnetic bead extraction and flow cytometry, respectively. MP function as assessed by thrombin generation was determined using a fluorogenic assay. RESULTS: Ten children had AIS recurrence while 36 had a single AIS event. CECs were raised in children with recurrent AIS, compared to those with no recurrence (p = 0.0001), and in controls (p = 0.0001). Total circulating annexin V+ MPs were significantly greater in children with recurrence than in those with no recurrence (p = 0.0020). These MPs were of endothelial or platelet origin, and a subpopulation expressed tissue factor. Finally, MP-mediated thrombin generation was enhanced in children with recurrent AIS compared to those with no recurrence (p = 0.0001), providing a link between inflammation, endothelial injury, and increased thrombotic tendency. CONCLUSION: Despite the wide spectrum of clinical and radiologic presentation of childhood AIS, indices of endothelial injury and cellular activation are different in patients with single and recurrent events. This novel approach has potential for furthering understanding of AIS pathophysiology and prognosis.

Postmortem tandem mass spectrometry profiling for detection of infection in unexpected infant death.

Numerous hypotheses have been suggested to explain the cause of sudden unexpected infant death, including infection. As part of the autopsy, routine ancillary investigations are performed, including blood/bile tandem mass spectrometry (TMS) primarily for detection of metabolic disease. The aim of this study was to evaluate and assess TMS derived acylcarnitine profiles to determine whether infectious deaths were associated with characteristic profiles. As part of a retrospective study including >2,500 pediatric autopsies at a single specialist centre over a 14 year period, acylcarnitine profiles were reviewed. Using multiple linear regression, standardised residuals were prepared and findings compared between different cause of death groups, including unexplained, focal infection, microbiological infection and accidental injuries. 415 blood samples from SUDI autopsies were identified. Statistically significant differences in TMS profiles were identified between those dying of infection and the unexplained SUDI group, including changes in free carnitine, short chain acylcarnitines and octanoylcarnitine. Cases with microbiological infection diagnosed only from postmortem cultures did not show any significant difference from the unexplained group. Postmortem TMS profiling identifies SUDI deaths which are associated with histological evidence of infection, and an acylcarnitine profile suggesting perturbation of oxidative metabolism. Such findings raise the possibility that more comprehensive TMS profiling may offer additional diagnostic clues beyond screening for metabolic disorders, and may contribute to determination of mode of death.

Anti-neutrophil cytoplasmic antibodies stimulate release of neutrophil microparticles.

The mechanisms by which anti-neutrophil cytoplasmic antibodies (ANCAs) may contribute to the pathogenesis of ANCA-associated vasculitis are not well understood. In this study, both polyclonal ANCAs isolated from patients and chimeric proteinase 3-ANCA induced the release of neutrophil microparticles from primed neutrophils. These microparticles expressed a variety of markers, including the ANCA autoantigens proteinase 3 and myeloperoxidase. They bound endothelial cells via a CD18-mediated mechanism and induced an increase in endothelial intercellular adhesion molecule-1 expression, production of endothelial reactive oxygen species, and release of endothelial IL-6 and IL-8. Removal of the neutrophil microparticles by filtration or inhibition of reactive oxygen species production with antioxidants abolished microparticle-mediated endothelial activation. In addition, these microparticles promoted the generation of thrombin. In vivo, we detected more neutrophil microparticles in the plasma of children with ANCA-associated vasculitis compared with that in healthy controls or those with inactive vasculitis. Taken together, these results support a role for neutrophil microparticles in the pathogenesis of ANCA-associated vasculitis, potentially providing a target for future therapeutics.