Expression of TIGIT, PD-1 and HLA-DR/CD38 markers on CD8-T cells of children and adolescents infected with HIV and uninfected controls.

Immune exhaustion and senescence are scarcely studied in HIV-pediatric patients. We studied the circulatory CD8 T cells activation/exhaustion and senescent phenotype of children and adolescents vertically infected with HIV or uninfected controls based on the expression of human leukocyte antigen (HLA-DR), CD38, T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT), programmed death 1 (PD-1) and CD57 by flow cytometry, during approximately one year. Eleven HIV-infected (HI) and nine HIV-uninfected (HU) children/adolescents who received two doses or one dose of meningococcal C conjugate vaccine (MenC), respectively, were involved in this study. Blood samples were collected before the immunization (T0), 1-2 months after the first dose (T1), and 1-2 months after the second dose (T2), which was administered approximately one year after the first one. HI patients not receiving combined antiretroviral therapy (cART) showed a higher frequency of CD8 T cells TIGIT+, PD-1+ or CD57+, as well as a higher frequency of CD8 T cells co-expressing CD38/HLA-DR/TIGIT or CD38/HLA-DR/PD-1 when compared to HI treated or HU individuals, at all times that they were assessed. CD8 T cells co-expressing CD38/DR/TIGIT were inversely correlated with the CD4/CD8 ratio but positively associated with viral load. The co-expression of CD38/DR/TIGIT or CD38/DR/PD-1 on CD8 T cells was also inversely associated with the CD4 T cells expressing co-stimulatory molecules CD127/CD28. The results showed a higher expression of exhaustion/senescence markers on CD8 T cells of untreated HI children/adolescents and its correlations with viral load.

Expression of TIGIT, PD-1 and HLA-DR/CD38 markers on CD8-T cells of children and adolescents infected with HIV and uninfected controls

ABSTRACT Immune exhaustion and senescence are scarcely studied in HIV-pediatric patients. We studied the circulatory CD8 T cells activation/exhaustion and senescent phenotype of children and adolescents vertically infected with HIV or uninfected controls based on the expression of human leukocyte antigen (HLA-DR), CD38, T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT), programmed death 1 (PD-1) and CD57 by flow cytometry, during approximately one year. Eleven HIV-infected (HI) and nine HIV-uninfected (HU) children/adolescents who received two doses or one dose of meningococcal C conjugate vaccine (MenC), respectively, were involved in this study. Blood samples were collected before the immunization (T0), 1-2 months after the first dose (T1), and 1-2 months after the second dose (T2), which was administered approximately one year after the first one. HI patients not receiving combined antiretroviral therapy (cART) showed a higher frequency of CD8 T cells TIGIT+, PD-1+ or CD57+, as well as a higher frequency of CD8 T cells co-expressing CD38/HLA-DR/TIGIT or CD38/HLA-DR/PD-1 when compared to HI treated or HU individuals, at all times that they were assessed. CD8 T cells co-expressing CD38/DR/TIGIT were inversely correlated with the CD4/CD8 ratio but positively associated with viral load. The co-expression of CD38/DR/TIGIT or CD38/DR/PD-1 on CD8 T cells was also inversely associated with the CD4 T cells expressing co-stimulatory molecules CD127/CD28. The results showed a higher expression of exhaustion/senescence markers on CD8 T cells of untreated HI children/adolescents and its correlations with viral load.

SYNERGISTIC IMMUNOMODULATORY ACTIVITY OF PROBIOTICS BIFIDOBACTERIUM ANIMALIS AND LACTOBACILLUS CASEI IN ENTEROAGGREGATIVE ESCHERICHIA COLI (EAEC)-INFECTED CACO-2 CELLS.

BACKGROUND: Enteroaggregative Escherichia coli (EAEC) is an E. coli pathotype that presents aggregative adhesion patterns on in vitro cultivated cells, mainly related to persistent diarrhea cases in children. EAEC virulence factors are important for host colonization and pathogeni-city. Intestinal epithelial cells (IECs) recognize pathogen-associated molecular patterns (PAMPs) and initiate an immune response. Several studies using in vivo and in vitro models emphasize the probiotic activity and immunomodulatory capacity of Lactobacillus and Bifidobacterium species. OBJECTIVE: To evaluate the modulation of cytokine production by probiotics Bifidobacterium animalis and Lactobacillus casei in human intestinal Caco-2 cells exposed to different strains of EAEC. METHODS: Caco-2 cells were incubated with EAEC strains in the presence or absence of probiotics. The production of cytokines IL-8, TNF-α, IL-1ß and IL-10 was evaluated in the supernatants by a sandwich enzyme-linked immunosorbent assay (ELISA). RESULTS: Cytokine production did not change when uninfected and EAEC-infected Caco-2 cells were exposed to probiotics separately. All EAEC induced a significant increase in IL-8 production by Caco-2 cells, but the probiotics, even together, could not reduce its production. On the other hand, the synergic activity of probiotic strains significantly increased TNF-α production but decreased the basal production of IL-1ß. Also, probiotics induced a significant increase in the production of the anti-inflammatory cytokine IL-10 during EAEC infection. CONCLUSION: Our results reinforce the synergistic immunomodulatory activity of probiotics during EAEC infection.

Vitamin D is directly associated with favorable glycemic, lipid, and inflammatory profiles in individuals with at least one component of metabolic syndrome irrespective of total adiposity: Pró-Saúde Study, Brazil.

Vitamin D insufficiency has been suggested as a risk factor for several metabolic disorders. The objective of the study was to investigate the association between serum 25 hydroxyvitamin D [25(OH)D] and metabolic health markers of Brazilian individuals with normal-weight, overweight or obesity. We hypothesized that serum 25(OH)D would be inversely associated with glycemic, lipid and inflammatory markers indicative of metabolic abnormality. Data of 511 individuals (33-79 years), recruited from a longitudinal investigation (Pró-Saúde Study), were analyzed cross-sectionally. Anthropometric, biochemical, body composition, socio-demographic and lifestyle data were collected. Based on body mass index (BMI; normal weight, overweight, obesity) and metabolic health (metabolically healthy (MH) and metabolically unhealthy (MU)) categories, the participants were classified into 6 phenotypes. Individuals having zero components of the metabolic syndrome were considered as "MH". MH obesity was frequent in 2.0% of the participants and 56.0% exhibited vitamin D insufficiency (<20 ng/mL). In the subgroups of the same BMI category, there were no significant differences in 25(OH)D concentrations between individuals classified as MH and MU. After adjustments (including %body fat and BMI), an inverse association was observed between 25(OH)D and visceral adipose tissue (B = -6.46, 95% confidence interval, CI: -12.87, -0.04), leptin (B = -0.09, 95% confidence interval, CI: -0.14, -0.03), insulin (B = -0.21, 95%CI: -0.34, -0.07), HOMA-IR (B = -0.06, 95%CI: -0.10, -0.02), triglycerides (B = -2.44, 95%CI: -3.66, -1.22), and TNF-α (B = -0.12, 95%CI: -0.24, -0.005) only in MU individuals. Our results indicate that the association of 25(OH)D concentrations with a favorable biochemical profile (glycemic, lipidic and inflammatory) seems to depend on the individual's overall metabolic health, suggesting more benefits from higher serum vitamin D in MU individuals, regardless of their adiposity.

Association between circulating exhausted CD4+ T cells with poor meningococcal C conjugate vaccine antibody response in HIV-infected children and adolescents.

OBJECTIVES: To investigate the expression levels of surface markers of activation (CD38 and HLA-DR), inhibition (PD-1, TIGIT and CD57) and co-stimulation (CD28 and CD127) on CD4+ T cells of children/adolescents with vertical HIV infection (HI patients) and HIV-uninfected (HU) controls vaccinated with the meningococcal C conjugate vaccine (MCC). METHODS: HI patients (n=12), aged 8-17 years, were immunized with two MCC injections, while HU controls (n=9), aged 5.3-10.7 years, received a single MCC dose (as per national recommendation at the time of this study, a single MCC vaccine dose should be given for healthy children and youth aged 1-18 years). The HI patients were categorized according to the combined antiretroviral therapy (cART) treatment. Blood samples were obtained before vaccination, after priming, and after the administration of a booster dose of vaccine to determine the serum bactericidal antibody (SBA) titers and the expression levels of surface markers on CD4+ T cells by flow cytometry. The levels of serum cytokines, IL-4 and CXCL-13 were also measured using Luminex kits. RESULTS: The co-expression of the TIGIT-HLA-DR-CD38 molecules increased in the CD4+ T cells of HI patients/no-cART who also showed a lower frequency of CD127+CD28+ CD4+ T cells than HI patients/cART and HU group subjects. There were significant negative correlations between the frequency of exhausted CD4+ T cells and the SBA response. IL-4 levels were higher in HI patients/cART and positively correlated with SBA titers but negatively associated with the expression of exhaustion markers. Moreover, the CXCL-13 levels were positively correlated with the exhausted CD4+ T cells. CONCLUSION: The results of our study suggest that the co-expression of exhaustion markers and/or loss of co-stimulatory molecules influence the SBA response in HI patients.

Atividade imunomoduladora sinérgica de probióticos Bifidobacterium animalis e Lactobacillus casei em células Caco-2 infectadas com Escherichia coli enteroagregativa (EAEC) / Synergistic immunomodulatory activity of probiotics bifidobacterium animalis and lactobacillus casei in enteroaggregative escherichia coli (eaec)-infected caco-2 cells

ABSTRACT BACKGROUND: Enteroaggregative Escherichia coli (EAEC) is an E. coli pathotype that presents aggregative adhesion patterns on in vitro cultivated cells, mainly related to persistent diarrhea cases in children. EAEC virulence factors are important for host colonization and pathogeni­city. Intestinal epithelial cells (IECs) recognize pathogen-associated molecular patterns (PAMPs) and initiate an immune response. Several studies using in vivo and in vitro models emphasize the probiotic activity and immunomodulatory capacity of Lactobacillus and Bifidobacterium species. OBJECTIVE To evaluate the modulation of cytokine production by probiotics Bifidobacterium animalis and Lactobacillus casei in human intestinal Caco-2 cells exposed to different strains of EAEC. METHODS: Caco-2 cells were incubated with EAEC strains in the presence or absence of probiotics. The production of cytokines IL-8, TNF-α, IL-1β and IL-10 was evaluated in the supernatants by a sandwich enzyme-linked immunosorbent assay (ELISA). RESULTS: Cytokine production did not change when uninfected and EAEC-infected Caco-2 cells were exposed to probiotics separately. All EAEC induced a significant increase in IL-8 production by Caco-2 cells, but the probiotics, even together, could not reduce its production. On the other hand, the synergic activity of probiotic strains significantly increased TNF-α production but decreased the basal production of IL-1ß. Also, probiotics induced a significant increase in the production of the anti-inflammatory cytokine IL-10 during EAEC infection. CONCLUSION: Our results reinforce the synergistic immunomodulatory activity of probiotics during EAEC infection.

RESUMO CONTEXTO: Escherichia coli enteroagregativa (EAEC) é um patotipo de E. coli que apresenta o padrão de aderência agregativa em células cultivadas in vitro, sendo comumente relacionada a casos de diarreia persistente em crianças. Fatores de virulência presentes em EAEC são importantes para a colonização do hospedeiro e patogenicidade. As células epiteliais intestinais (IECs) reconhecem padrões moleculares associados a patógenos (PAMPs) e iniciam uma resposta imune. Vários estudos usando modelos in vivo e in vitro enfatizam a atividade probiótica e a capacidade imunomoduladora de espécies de Lactobacillus e Bifidobacterium. OBJETIVO: Este estudo avaliou a modulação da produção de citocinas pelos probióticos Bifidobacterium animalis and Lactobacillus casei em células intestinais humanas Caco-2 expostas a diferentes cepas de EAEC. MÉTODOS: As células Caco-2 foram incubadas com as cepas de EAEC na presença ou ausência dos probióticos. A produção das citocinas IL-8, TNF-α, IL-1β e IL-10 foi avaliada nos sobrenadantes por ELISA sanduíche. RESULTADOS: Não houve alteração na produção de citocinas quando as células não infectadas e as células infectadas com EAEC foram expostas aos probióticos separadamente. Todas as cepas de EAEC induziram aumento significativo na produção de IL-8 pelas células Caco-2, mas os probióticos, ainda que em conjunto, não foram capazes de reduzir a produção desta citocina. Por outro lado, as cepas de probióticos aumentaram significativamente a produção de TNF-α mas diminuíram a produção basal de IL-1ß. Além disso, os probióticos induziram um aumento significativo na produção da citocina anti-inflamatória IL-10 durante a infecção por EAEC. CONCLUSÃO: Nossos resultados reforçam a atividade imunomodulatória sinérgica dos probióticos durante a infecção de EAEC.

Association between circulating exhausted CD4+ T cells with poor meningococcal C conjugate vaccine antibody response in HIV-infected children and adolescents

OBJECTIVES: To investigate the expression levels of surface markers of activation (CD38 and HLA-DR), inhibition (PD-1, TIGIT and CD57) and co-stimulation (CD28 and CD127) on CD4+ T cells of children/adolescents with vertical HIV infection (HI patients) and HIV-uninfected (HU) controls vaccinated with the meningococcal C conjugate vaccine (MCC). METHODS: HI patients (n=12), aged 8-17 years, were immunized with two MCC injections, while HU controls (n=9), aged 5.3-10.7 years, received a single MCC dose (as per national recommendation at the time of this study, a single MCC vaccine dose should be given for healthy children and youth aged 1-18 years). The HI patients were categorized according to the combined antiretroviral therapy (cART) treatment. Blood samples were obtained before vaccination, after priming, and after the administration of a booster dose of vaccine to determine the serum bactericidal antibody (SBA) titers and the expression levels of surface markers on CD4+ T cells by flow cytometry. The levels of serum cytokines, IL-4 and CXCL-13 were also measured using Luminex kits. RESULTS: The co-expression of the TIGIT-HLA-DR-CD38 molecules increased in the CD4+ T cells of HI patients/no-cART who also showed a lower frequency of CD127+CD28+ CD4+ T cells than HI patients/cART and HU group subjects. There were significant negative correlations between the frequency of exhausted CD4+ T cells and the SBA response. IL-4 levels were higher in HI patients/cART and positively correlated with SBA titers but negatively associated with the expression of exhaustion markers. Moreover, the CXCL-13 levels were positively correlated with the exhausted CD4+ T cells. CONCLUSION: The results of our study suggest that the co-expression of exhaustion markers and/or loss of co-stimulatory molecules influence the SBA response in HI patients.

Baseline Circulating Activated TFH and Tissue-Like Exhausted B Cells Negatively Correlate With Meningococcal C Conjugate Vaccine Induced Antibodies in HIV-Infected Individuals.

Since 2006, meningococcal serogroup C (MenC) conjugate (MCC) vaccines have been supplied by the Brazilian government for HIV-infected children under 13 years old. For measuring protection against MenC, the serum bactericidal antibody (SBA) assay is the method of choice. The characterization of T follicular helper cells (TFH) cells has been an area of intensive study because of their significance in multiple human diseases and in vaccinology. The objective of this study was to characterize the phenotype of peripheral TFH cells and B cells and how they associated with each other and with SBA levels induced by vaccination as well as with serum cytokine levels of HIV-infected and non-infected children and adolescents. We found that CD27-IgD-CD21-CD38+ (exhausted B cells) as well as short-lived plasmablasts (CD27+IgD-CD21-CD38+) are increased in cART treated HIV patients and negatively associated with MCC vaccine induced SBA levels. Baseline frequency of activated peripheral TFH cells was a negative correlate for SBA response to MCC vaccine but positively correlated with circulating plasmablast frequency. Baseline IL4-levels positively associated with SBA response but showed a negative correlation with activated peripheral TFH cells frequency. The increased frequency of activated peripheral TFH cells found in non-responders to the vaccine implies that higher activation/differentiation of CD4 T cells within the lymph node is not necessarily associated with induction of vaccine responses.

INTRACELLULAR PERSISTENCE OF ENTEROAGGREGATIVE ESCHERICHIA COLI INDUCES A PROINFLAMMATORY CYTOKINES SECRETION IN INTESTINAL EPITHELIAL T84 CELLS.

BACKGROUND: The competence of enteroaggregative Escherichia coli (EAEC) to adhere to the intestinal epithelium of the host is a key role to the colonization and disease development. The virulence genes are crucial for EAEC pathogenicity during adherence, internalization and persistence in the host. The overwhelming majority of antigen encounters in a host occurs on the intestine surface, which is considered a part of innate mucosal immunity. Intestinal epithelial cells (IECs) can be activated by microorganisms and induce an immune response. OBJECTIVE: The present study investigated the interaction of invasive EAEC strains with T84 intestinal epithelial cell line in respect to bacterial invasiveness, persistence and cytokines production. METHODS: We evaluated intracellular persistence of invasive EAEC strains (H92/3, I49/3 and the prototype 042) and production of cytokines by sandwich ELISA in T84 cells upon 24 hours of infection. RESULTS: The survival rates of the prototype 042 was 0.5x103 CFU/mL while survival of I49/3 and H92/3 reached 3.2x103 CFU/mL and 1.4x103 CFU/mL, respectively. Infection with all EAEC strains tested induced significant amounts of IL-8, IL-6 and TNF-α compared to uninfected T84 cells. CONCLUSION: These data showed that infection by invasive EAEC induce a proinflammatory immune response in intestinal epithelial T84 cells.

A persistência intracelular de Escherichia coli enteroagregativa induz a secreção de citocinas pró-inflamatórias em células epiteliais intestinais T84 / Intracellular persistence of enteroaggregative escherichia coli induces a proinflammatory cytokines secretion in intestinal epithelial t84 cells

ABSTRACT BACKGROUND: The competence of enteroaggregative Escherichia coli (EAEC) to adhere to the intestinal epithelium of the host is a key role to the colonization and disease development. The virulence genes are crucial for EAEC pathogenicity during adherence, internalization and persistence in the host. The overwhelming majority of antigen encounters in a host occurs on the intestine surface, which is considered a part of innate mucosal immunity. Intestinal epithelial cells (IECs) can be activated by microorganisms and induce an immune response. OBJECTIVE: The present study investigated the interaction of invasive EAEC strains with T84 intestinal epithelial cell line in respect to bacterial invasiveness, persistence and cytokines production. METHODS: We evaluated intracellular persistence of invasive EAEC strains (H92/3, I49/3 and the prototype 042) and production of cytokines by sandwich ELISA in T84 cells upon 24 hours of infection. RESULTS: The survival rates of the prototype 042 was 0.5x103 CFU/mL while survival of I49/3 and H92/3 reached 3.2x103 CFU/mL and 1.4x103 CFU/mL, respectively. Infection with all EAEC strains tested induced significant amounts of IL-8, IL-6 and TNF-α compared to uninfected T84 cells. CONCLUSION: These data showed that infection by invasive EAEC induce a proinflammatory immune response in intestinal epithelial T84 cells.

RESUMO CONTEXTO: A competência de Escherichia coli enteroagregativa (EAEC) para aderir ao epitélio intestinal do hospedeiro é um papel fundamental para a colonização e o desenvolvimento da doença. Os genes de virulência são cruciais para a patogenicidade de EAEC durante a aderência, a internalização e a persistência no hospedeiro. A grande maioria dos encontros de antígenos em um hospedeiro ocorre na superfície do intestino, que é considerada parte da imunidade inata da mucosa. As células epiteliais intestinais (IECs) podem ser ativadas por micro-organismos e induzir uma resposta imune. OBJETIVO: O presente estudo investigou a interação de cepas invasoras de EAEC com a linhagem celular epitelial intestinal T84 em relação a invasão bacteriana, a persistência e a produção de citocinas. MÉTODOS: Avaliamos a persistência intracelular de cepas invasoras de EAEC (H92/3, I49/3 e o protótipo 042) e a produção de citocinas por ELISA "sanduíche" em células T84 após 24 horas de infecção. RESULTADOS: As taxas de sobrevivência da cepa protótipo 042 foi de 0,5x103 UFC/mL, enquanto a sobrevivência de I49/3 e H92/3 atingiu 3,2x103 UFC/mL e 1,4x103 UFC/mL, respectivamente. A infecção com todas as cepas EAEC testadas induziu quantidades significativas de IL-8, IL-6 e TNF-α em comparação com células T84 não infectadas. CONCLUSÃO: Estes dados mostraram que a infecção por EAEC invasoras induzem uma resposta imune pró-inflamatória em células epiteliais intestinais T84.

Safety and immune response after two-dose meningococcal C conjugate immunization in HIV-infected children and adolescents in Rio de Janeiro, Brazil.

We aimed to evaluate immunogenicity and adverse events (AEs) after a booster dose of Meningococcal C conjugated (MCC) vaccine in HIV-infected children and adolescents, who had a previous low seroconversion rate after priming with MCC, at a reference HIV-care center in Rio de Janeiro. METHODS: 2-18 years old HIV-infected subjects with CD4+ T-lymphocyte cell (CD4) ≥15%, without active infection or antibiotic use, were enrolled to receive 2 doses of conjugated meningococcal C oligosaccharide-CRM197 12-18 months apart. All patients were evaluated before and 1-2 months after immunization for seroprotection [defined as human serum bactericidal activity (hSBA) titer ≥1:4]. AEs were assessed at 20 min, 3 and 7 days after each dose. Factors independently associated with seroprotection were studied. RESULTS: 156 subjects were enrolled and 137 received a booster MCC dose. 55% were female, and median age was 12 years. Eight-nine percent were receiving combined antiretroviral therapy (cART) at the booster visit (median duration of 7.7 years), 59.9% had undetectable viral load (VL) at baseline, and 56.2% at the booster visit. Seroprotection was achieved in 78.8% (108/137) subjects, with a significantly higher GMT than after the priming dose (p < 0.01). Mild AEs were experienced after a second MCC dose (38%). In logistic regression, undetectable viral load at entry [odds ratio (OR) = 7.1, 95% confidence interval (95%CI): 2.14-23.37], and probably higher CD4 percent at the booster immunization visit (OR): 1.1, 95%CI: 1.01-1.17 were associated with seroprotection after a booster dose of MCC. CONCLUSION: A booster dose of MCC was safe and induced high seroprotection rate even 12-18 months after priming. MCC should be administered after maximum virologic suppression has been achieved. These results support the recommendation of 2-dose of MCC for primary immunization in HIV-infected children and adolescents with restored immune function.

A cross-reacting material CRM197 conjugate vaccine induces diphtheria toxin neutralizing antibody response in children and adolescents infected or not with HIV.

Anti-diphtheria antibody levels decrease with aging, and frequent booster vaccinations are required to maintain herd immunity. We analyzed the diphtheria toxin neutralizing antibody (DT-Nab) response induced by a conjugate vaccine (meningococcal C polysaccharide-CRM197) in HIV-vertically infected (HI) children and adolescents and healthy controls (HC) with matched age. We report the association of DT-Nab with the bactericidal antibodies to serogroup C meningococcus (MenC). Before vaccination, 21 HI patients (50%) had no protection against diphtheria (≤0.01IU/ml of antibody) and only 8 (19%) showed complete protection (≥0.1IU/ml). About half of the HC (56%) had complete protection before immunization and 6 subjects (12%) had no protection against diphtheria. After one and two vaccine injections, 96% of HC and 64% of HI vaccinees, respectively, showed full protection against diphtheria. These data indicate that CRM197 was able to induce primary and/or booster response in both groups of individuals.

Association of serum bactericidal antibody and opsonic antibody levels after Neisseria meningitidis serogroup C conjugate vaccine in Brazilian children and adolescents infected or not infected with HIV.

Neisseria meningitidis serogroup C (MenC) is the main causative agent of meningitis in Brazil. HIV infection affects the quality of the immune system. HIV+ children have an increased risk of infection to encapsulated bacteria such as N. meningitidis. We evaluated the opsonic antibody (OPA) levels and its correlation with serum bactericidal antibody (SBA) levels induced by one and two doses of a MenC conjugate vaccine in children and adolescents HIV+ and HIV-exposed but uninfected children (HEU) group. Overall the data show the importance of two doses of vaccine for HIV+ individuals. About 79% and 58% of HIV+ patients showed SBA and OPA positive response after two doses of vaccine, respectively. For HEU group, 62% and 41% of patients showed SBA and OPA positive response after one dose of vaccine, respectively. A positive and significant association between SBA and OPA levels was seen after two doses of vaccine in HIV+ patients.

Immunogenicity and safety of meningococcal C conjugate vaccine in children and adolescents infected and uninfected with HIV in Rio de Janeiro, Brazil.

BACKGROUND: We aimed to evaluate the Meningococcal (Neisseria meningitidis) C conjugated (MCC) vaccine seroconversion and adverse events (AEs) in HIV-infected and HIV-uninfected children and adolescents in Rio de Janeiro, Brazil. METHODS: HIV-infected or HIV-uninfected subjects, 2-18 years old, with CD4+ T-lymphocyte cell (CD4) percentage >15%, without active infection or antibiotic use, were enrolled. All patients were evaluated before and 1-2 months after immunization for seroconversion (defined as ≥4-fold titer increase in human serum bactericidal activity) and at 20 minutes, 3 and 7 days after immunization for AEs. Factors associated with seroconversion among HIV-infected group were studied. RESULTS: Two hundred four subjects were enrolled: 154 HIV-infected and 50 HIV-uninfected. Median age was 12 years, and 53% were female. Among the HIV-infected group, 82 (53%) had a history of at least 1 C clinical category of Centers for Diseases Control and Prevention event, and 134 (87%) were using combination antiretroviral therapy. The median nadir CD4 percentage was 13% (0-47%). Seventy-six (37.3%) experienced mild AEs. Seroconversion occurred in 46 of 154 (30%) in the HIV-infected group and in 38 of 50 (76%) in the uninfected group (P < 0.01). Factors associated with seroconversion in the HIV-infected group were as follows: never had a C clinical category event [odds ratio (OR) = 2.1, 95% confidence interval (CI): 1.0-4.4]; undetectable viral load at immunization (OR: 2.4, 95% CI: 1.1-5.2) and higher CD4 nadir/100 cells (OR: 1.1, 95% CI: 1.0-1.2). CONCLUSION: MCC vaccine should be administered to HIV-infected children and adolescents after maximum immunologic and virologic benefits have been achieved with combination antiretroviral therapy. Our data suggest that a single dose of MCC vaccine is insufficient for HIV-infected individuals 2-18 years of age.

Subsets of memory CD4+ T cell and bactericidal antibody response to Neisseria meningitidis serogroup C after immunization of HIV-infected children and adolescents.

Meningococcal disease is endemic in Brazil, with periodic outbreaks and case fatality rates reach as high as 18 to 20% of cases. Conjugate vaccines against meningococci are immunogenic in healthy children. However, we have previously shown a poor bactericidal antibody response to a Men C conjugate vaccine in Brazilian HIV-infected children and adolescents after a single vaccine administration. The goal of the present work was to investigate associations between bactericidal antibody response induced by MenC vaccine and the frequency and activation profile (expression of CD38, HLA-DR and CCR5 molecules) of total CD4+ memory T cell sub-populations in HIV-1-infected children and adolescents. Responders to vaccination against MenC had a predominance (about 44%) of CD4+ TINTERMEDIATE subset followed by TTRANSITIONAL memory subset (23 to 26%). Importantly, CD4+ TINT frequency was positively associated with bactericidal antibody response induced by vaccination. The positive correlation persisted despite the observation that the frequency TINT CD38+HLA-DR+ was higher in responders. In contrast, CD4+ TCENTRAL MEMORY (TCM) subset negatively correlated with bactericidal antibodies. In conclusion, these data indicate that less differentiated CD+ T cells, like TCM may be constantly differentiating into intermediate and later differentiated CD4+ T cell subsets. These include CD4 TINT subset which showed a positive association with bactericidal antibodies.

Inhibition of caspase-8 activity promotes protective Th1- and Th2-mediated immunity to Leishmania major infection.

We investigated how apoptosis pathways mediated by death receptors and caspase-8 affect cytokine responses and immunity to Leishmania major parasites. Splenic CD4 T cells undergo activation-induced apoptosis, and blockade of FasL-Fas interaction increased IFN-γ and IL-4 cytokine responses to L. major antigens. To block death receptor-induced death, we used mice expressing a T cell-restricted transgene for vFLIP. Inhibition of caspase-8 activation in vFLIP mice enhanced Th1 and Th2 cytokine responses to L. major infection, even in the Th1-prone B6 background. We also observed increased NO production by splenocytes from vFLIP mice upon T cell activation. Despite an exacerbated Th2 response, vFLIP mice controlled better L. major infection, with reduced lesions and lower parasite loads compared with WT mice. Moreover, injection of anti-IL-4 mAb in infected vFLIP mice disrupted control of parasite infection. Therefore, blockade of caspase-8 activity in T cells improves immunity to L. major infection by promoting increased Th1 and Th2 responses.

CD4+ T-cell activation impairs serogroup C Neisseria meningitis vaccine response in HIV-infected children.

OBJECTIVE: To investigate the influence of CD4 T-cell activation and regulatory populations in HIV-infected children antibody response to vaccination with a conjugate C polysaccharide vaccine. DESIGN: CD4 T-cell activation was evaluated by expression of CD38, HLA-DR and CCR5 molecules. Regulatory CD4 T cells (TReg) were characterized as FoxP3CD127CD25 and inducer T cells (TInd) as CD4FoxP3CD25CD39. METHODS: All patients (n = 36) were HIV-vertically infected, aged 2-17 years-old and were vaccinated with one vaccine injection. Blood samples were obtained before and after immunization to determine bactericidal antibody titers (SBA), CD4 T-cell activation and frequency of TReg and TInd subsets (multiparametric flow cytometry). RESULTS: Children not-responding (n = 18) to MenC vaccine expressed higher frequency of activated CD4 T cells (HLA-DRCD38CCR5) than responders (n = 18), both before and after vaccination (P < 0.05). A significant higher frequency of TReg was detected in responders compared with nonresponders (P = 0.0001). We also detected an inverse correlation between CD4DRCD38CCR5 (P = 0.01) or CD4DRCD38 (P = 0.02) T cells and TReg cell frequency after vaccination. CD4 T-cell activation negatively correlated (P = 0.006) with postvaccination SBA titers but a positive correlation (P = 0.0001) was detected between TReg cells and SBA. TReg and TInd subsets were inversely correlated (P = 0.04). CONCLUSION: Our findings suggest that higher CD4 T-cell activation leads to poor vaccine response in children living with HIV, which may be associated with a TReg/TInd disequilibrium.