Both CD4+ and CD8+ Lymphocytes Participate in the IFN-γ Response to Filamentous Hemagglutinin from Bordetella pertussis in Infants, Children, and Adults

Infant CD4+ T-cell responses to bacterial infections or vaccines have been extensively studied, whereas studies on CD8+ T-cell responses focused mainly on viral and intracellular parasite infections. Here we investigated CD8+ T-cell responses upon Bordetella pertussis infection in infants, children, and adults and pertussis vaccination in infants. Filamentous hemagglutinin-specific IFN-γ secretion by circulating lymphocytes was blocked by anti-MHC-I or -MHC-II antibodies, suggesting that CD4+ and CD8+ T lymphocytes are involved in IFN-γ production. Flow cytometry analyses confirmed that both cell types synthesized antigen-specific IFN-γ, although CD4+ lymphocytes were the major source of this cytokine. IFN-γ synthesis by CD8+ cells was CD4+ T cell dependent, as evidenced by selective depletion experiments. Furthermore, IFN-γ synthesis by CD4+ cells was sometimes inhibited by CD8+ lymphocytes, suggesting the presence of CD8+ regulatory T cells. The role of this dual IFN-γ secretion by CD4+ and CD8+ T lymphocytes in pertussis remains to be investigated

Short- and Long-term Immunological and Virological Outcome in HIV-Infected Infants According to the Age at Antiretroviral Treatment Initiation

The clinical benefit of antiretroviral therapy in infants is established. In this cohort collaboration, we compare immunological and virological response to treatment started before or after 3 months of age. Early initiation provides a better short-term response, although evolution after 12 months of age is similar in both group

HCV treatment in children and young adults with HIV/HCV co-infection in Europe

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Predominant Influence of Environmental Determinants on the Persistence and Avidity Maturation of Antibody Responses to Vaccines in Infants

BackgroundImmune responses are complex traits influenced by genetic and environmental factors. We previously reported that genetic factors control early antibody responses to vaccines in Gambian infants. For the present study, we evaluated the determinants of the memory phase of immunoglobulin G (IgG) responses MethodsAntibody responses to tetanus toxoid (TT), measles vaccines, and environmental antigens (total IgG levels) were measured in 210 Gambian twin pairs recruited at birth. Intrapair correlations for monozygous and dizygous pairs were compared to estimate the environmental and genetic components of variations in response ResultsIn contrast to antibody responses measured in infants at age 5 months, 1 month after immunization, no significant contribution of genetic factors to anti-TT antibody and total IgG levels was detected at age 12 months. Genetic factors controlled measles antibody responses in 12-month-old infants, which indicates that the increasing influence of environmental determinants on anti-TT responses was not related to the older age of the children but, rather, to the time elapsed since immunization. Environmental factors also predominantly controlled affinity maturation and the production of high-avidity antibodies to TT ConclusionsGenetic determinants control the early phase of the vaccine antibody response in Gambian infants, whereas environmental determinants predominantly influence antibody persistence and avidity maturatio

Pattern recognition receptor-mediated cytokine response in infants across 4 continents⋆

Background Susceptibility to infection as well as response to vaccination varies among populations. To date, the underlying mechanisms responsible for these clinical observations have not been fully delineated. Because innate immunity instructs adaptive immunity, we hypothesized that differences between populations in innate immune responses may represent a mechanistic link to variation in susceptibility to infection or response to vaccination. Objective Determine whether differences in innate immune responses exist among infants from different continents of the world. Methods We determined the innate cytokine response following pattern recognition receptor (PRR) stimulation of whole blood from 2-year-old infants across 4 continents (Africa, North America, South America, and Europe). Results We found that despite the many possible genetic and environmental exposure differences in infants across 4 continents, innate cytokine responses were similar for infants from North America, South America, and Europe. However, cells from South African infants secreted significantly lower levels of cytokines than did cells from infants from the 3 other sites, and did so following stimulation of extracellular and endosomal but not cytosolic PRRs. Conclusions Substantial differences in innate cytokine responses to PRR stimulation exist among different populations of infants that could not have been predicted. Delineating the underlying mechanism(s) for these differences will not only aid in improving vaccine-mediated protection but possibly also provide clues for the susceptibility to infection in different regions of the world

Prevalence and effect of pre-treatment drug resistance on the virological response to antiretroviral treatment initiated in HIV-infected children - a EuroCoord-CHAIN-EPPICC joint project.

Few studies have evaluated the impact of pre-treatment drug resistance (PDR) on response to combination antiretroviral treatment (cART) in children. The objective of this joint EuroCoord-CHAIN-EPPICC/PENTA project was to assess the prevalence of PDR mutations and their association with virological outcome in the first year of cART in children. HIV-infected children <18 years initiating cART between 1998 and 2008 were included if having at least one genotypic resistance test prior to cART initiation. We used the World Health Organization 2009 resistance mutation list and Stanford algorithm to infer resistance to prescribed drugs. Time to virological failure (VF) was defined as the first of two consecutive HIV-RNA > 500 copies/mL after 6 months cART and was assessed by Cox proportional hazards models. All models were adjusted for baseline demographic, clinical, immunology and virology characteristics and calendar period of cART start and initial cART regimen. Of 476 children, 88 % were vertically infected. At cART initiation, median (interquartile range) age was 6.6 years (2.1-10.1), CD4 cell count 297 cells/mm(3) (98-639), and HIV-RNA 5.2 log10copies/mL (4.7-5.7). Of 37 children (7.8 %, 95 % confidence interval (CI), 5.5-10.6) harboring a virus with ≥1 PDR mutations, 30 children had a virus resistant to ≥1 of the prescribed drugs. Overall, the cumulative Kaplan-Meier estimate for virological failure was 19.8 % (95 %CI, 16.4-23.9). Cumulative risk for VF tended to be higher among children harboring a virus with PDR and resistant to ≥1 drug prescribed than among those receiving fully active cART: 32.1 % (17.2-54.8) versus 19.4 % (15.9-23.6) (P = 0.095). In multivariable analysis, age was associated with a higher risk of VF with a 12 % reduced risk per additional year (HR 0.88; 95 %CI, 0.82-0.95; P < 0.001). PDR was not significantly associated with a higher risk of VF in children in the first year of cART. The risk of VF decreased by 12 % per additional year at treatment initiation which may be due to fading of PDR mutations over time. Lack of appropriate formulations, in particular for the younger age group, may be an important determinant of virological failure

CD4 recovery following antiretroviral treatment interruptions in children and adolescents with HIV infection in Europe and Thailand

Objectives: The aim of the study was to explore factors associated with CD4 percentage (CD4%) reconstitution following treatment interruptions (TIs) of antiretroviral therapy (ART). Methods: Data from paediatric HIV-infected cohorts across 17 countries in Europe and Thailand were pooled. Children on combination ART (cART; at least three drugs from at least two classes) for > 6 months before TI of ≥ 30 days while aged < 18 years were included. CD4% at restart of ART (r-ART) and in the long term (up to 24 months after r-ART) following the first TI was modelled using asymptotic regression. Results: In 779 children with at least one TI, the median age at first TI was 10.1 [interquartile range (IQR) 6.4, 13.6] years and the mean CD4% was 27.3% [standard deviation (SD) 11.0%]; the median TI duration was 9.0 (IQR 3.5, 22.5) months. In regression analysis, the mean CD4% was 19.2% [95% confidence interval (CI) 18.3, 20.1%] at r-ART, and 27.1% (26.2, 27.9%) in the long term, with half this increase in the first 6 months. r-ART and long-term CD4% values were highest in female patients and in children aged < 3 years at the start of TI. Long-term CD4% was highest in those with a TI lasting 1 to <3 months, those with r-ART after year 2000 and those with a CD4% nadir ≥ 25% (all P < 0.001). The effect of CD4% nadir during the TI differed significantly (P = 0.038) by viral suppression at the start of the TI; in children with CD4% nadir < 15% during TI, recovery was better in those virally suppressed prior to the TI; viral suppression was not associated with recovery in children with CD4% nadir ≥ 25%. Conclusions: After restart of ART following TI, most children reconstituted well immunologically. Nevertheless, several factors predicted better immunological reconstitution, including younger age and higher nadir CD4% during TI

Height and timing of growth spurt during puberty in young people living with vertically acquired HIV in Europe and Thailand

Objective: The aim of this study was to describe growth during puberty in young people with vertically acquired HIV. Design: Pooled data from 12 paediatric HIV cohorts in Europe and Thailand. Methods: One thousand and ninety-four children initiating a nonnucleoside reverse transcriptase inhibitor or boosted protease inhibitor based regimen aged 1-10 years were included. Super Imposition by Translation And Rotation (SITAR) models described growth from age 8 years using three parameters (average height, timing and shape of the growth spurt), dependent on age and height-for-age z-score (HAZ) (WHO references) at antiretroviral therapy (ART) initiation. Multivariate regression explored characteristics associated with these three parameters. Results: At ART initiation, median age and HAZ was 6.4 [interquartile range (IQR): 2.8, 9.0] years and -1.2 (IQR: -2.3 to -0.2), respectively. Median follow-up was 9.1 (IQR: 6.9, 11.4) years. In girls, older age and lower HAZ at ART initiation were independently associated with a growth spurt which occurred 0.41 (95% confidence interval 0.20-0.62) years later in children starting ART age 6 to 10 years compared with 1 to 2 years and 1.50 (1.21-1.78) years later in those starting with HAZ less than -3 compared with HAZ at least -1. Later growth spurts in girls resulted in continued height growth into later adolescence. In boys starting ART with HAZ less than -1, growth spurts were later in children starting ART in the oldest age group, but for HAZ at least -1, there was no association with age. Girls and boys who initiated ART with HAZ at least -1 maintained a similar height to the WHO reference mean. Conclusion: Stunting at ART initiation was associated with later growth spurts in girls. Children with HAZ at least -1 at ART initiation grew in height at the level expected in HIV negative children of a comparable age

Outcomes of etravirine-based antiretroviral treatment in treatment-experienced children and adolescents living with HIV in Europe and Thailand

BACKGROUND: Etravirine (ETR) is approved as a component of second or third-line antiretroviral treatment (ART) for children living with HIV. We assessed the outcomes of ETR-based ART in children in routine care in Europe and Thailand. METHODS: Data on children aged <18 years at ETR start were pooled from 17 observational cohorts. Characteristics at ETR start, immunological and virological outcomes at 12 months, discontinuations, adverse events (AEs) and serious adverse events (SAEs) were described. Follow-up was censored at ETR discontinuation, death or last visit. RESULTS: 177 children ever received ETR. At ETR start, median [IQR] age was 15 [12,16] years, CD4 count 480 [287, 713] cells/mm3, 70% had exposure to ≥3 ART classes and 20% had viral load (VL) 3. Overall, 81 (46%) discontinued ETR by last follow-up. Median time to discontinuation was 23 [8, 47] months. Common reasons for discontinuation were treatment simplification (19%), treatment failure (16%) and toxicity (12%). Eight children (5%) had AEs causally associated with ETR, all dermatological/hypersensitivity reactions. Two were SAEs, both Stevens-Johnson Syndrome in children on regimens containing ETR and darunavir and were causally related to either drugs; both resolved following ART discontinuation. CONCLUSION: Children receiving ETR were predominantly highly treatment-experienced, over two-thirds were virally suppressed at 12 months