CD4 T follicular cells and B cells

© 2023 Wiley-VCH GmbH.Regulatory and effector cell responses to Plasmodium vivax, the most common human malaria parasite outside Africa, remain understudied in naturally infected populations. Here, we describe peripheral CD4 + T- and B-cell populations during and shortly after an uncomplicated P. vivax infection in 38 continuously exposed adult Amazonians. Consistent with previous observations, we found an increased frequency in CD4 + CD45RA - CD25 + FoxP3 + T regulatory cells that express the inhibitory molecule CTLA-4 during the acute infection, with a sustained expansion of CD21 - CD27 - atypical memory cells within the CD19 + B-cell compartment. Both Th1- and Th2-type subsets of CXCR5 + ICOS hi PD-1 + circulating T follicular helper (cTfh) cells, which are thought to contribute to antibody production, were induced during P. vivax infection, with a positive correlation between overall cTfh cell frequency and IgG antibody titers to the P. vivax blood-stage antigen MSP1 19 . We identified significant changes in cell populations that had not been described in human malaria, such as an increased frequency of CTLA-4 + T follicular regulatory cells that antagonize Tfh cells, and a decreased frequency of circulating CD24 hi CD27 + B regulatory cells in response to acute infection. In conclusion, we disclose a complex immunoregulatory network that is critical to understand how naturally acquired immunity develops in P. vivax malaria.publishersversionepub_ahead_of_prin

Adjuvant requirement for successful immunization with recombinant derivatives of Plasmodium vivax merozoite surface protein-1 delivered via the intranasal route

Recently, we generated two bacterial recombinant proteins expressing 89 amino acids of the C-terminal domain of the Plasmodium vivax merozoite surface protein-1 and the hexa-histidine tag (His6MSP1(19)). One of these recombinant proteins contained also the amino acid sequence of the universal pan allelic T-cell epitope (His(6)MSP1(19)-PADRE). in the present study, we evaluated the immunogenic properties of these antigens when administered via the intra-nasal route in the presence of distinct adjuvant formulations. We found that C57BL/6 mice immunized with either recombinant proteins in the presence of the adjuvants cholera toxin (CT) or the Escherichia coli heat labile toxin ( LT) developed high and long lasting titers of specific serum antibodies. the induced immune responses reached maximum levels after three immunizing doses with a prevailing IgG1 subclass response. in contrast, mice immunized by intranasal route with His(6)MSP1(19)-PADRE in the presence of the synthetic oligonucleotides adjuvant CpG ODN 1826 developed lower antibody titers but when combined to CT, CpG addition resulted in enhanced IgG responses characterized by lower IgG1 levels. Considering the limitations of antigens formulations that can be used in humans, mucosal adjuvants can be a reliable alternative for the development of new strategies of immunization using recombinant proteins of P. vivax.Universidade Federal de São Paulo, Dept Microbiol Imunol Parasitol, Escola Paulista Med, BR-04044010 São Paulo, BrazilUniversidade Federal de São Paulo, Ctr Interdisciplinar Terapia Genica, Escola Paulista Med, BR-04044010 São Paulo, BrazilUniv São Paulo, Dept Microbiol, Inst Ciencias Biomed, São Paulo, BrazilUniv São Paulo, Dept Anal Clin & Toxicol, Fac Ciencias Farmaceut, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Imunol Parasitol, Escola Paulista Med, BR-04044010 São Paulo, BrazilUniversidade Federal de São Paulo, Ctr Interdisciplinar Terapia Genica, Escola Paulista Med, BR-04044010 São Paulo, BrazilWeb of Scienc

Malaria Vaccine Development: Are Bacterial Flagellin Fusion Proteins the Bridge between Mouse and Humans?

In the past 25 years, the development of an effective malaria vaccine has become one of the biggest riddles in the biomedical sciences. Experimental data using animal infection models demonstrated that it is possible to induce protective immunity against different stages of malaria parasites. Nonetheless, the vast body of knowledge has generated disappointments when submitted to clinical conditions and presently a single antigen formulation has progressed to the point where it may be translated into a human vaccine. In parallel, new means to increase the protective effects of antigens in general have been pursued and depicted, such as the use of bacterial flagellins as carriers/adjuvants. Flagellins activate pathways in the innate immune system of both mice and humans. The recent report of the first Phase I clinical trial of a vaccine containing a Salmonella flagellin as carrier/adjuvant may fuel the use of these proteins in vaccine formulations. Herein, we review the studies on the use of recombinant flagellins as vaccine adjuvants with malarial antigens in the light of the current state of the art of malaria vaccine development. The available information indicates that bacterial flagellins should be seriously considered for malaria vaccine formulations to the development of effective human vaccines

Importance of CD8 T cell-mediated immune response during intracellular parasitic infections and its implications for the development of effective vaccines

Obligatory intracellular parasites such as Plasmodium sp, Trypanosoma cruzi, Toxoplasma gondii and Leishmania sp are responsible for the infection of hundreds of millions of individuals every year. These parasites can deliver antigens to the host cell cytoplasm that are presented through MHC class I molecules to protective CD8 T cells. The in vivo priming conditions of specific CD8 T cells during natural infection are largely unknown and remain as an area that has been poorly explored. The antiparasitic mechanisms mediated by CD8 T cells include both interferon-g-dependent and -independent pathways. The fact that CD8 T cells are potent inhibitors of parasitic development prompted many investigators to explore whether induction of these T cells can be a feasible strategy for the development of effective subunit vaccines against these parasitic diseases. Studies performed on experimental models supported the hypothesis that CD8 T cells induced by recombinant viral vectors or DNA vaccines could serve as the basis for human vaccination. Regimens of immunization consisting of two different vectors (heterologous prime-boost) are much more efficient in terms of expansion of protective CD8 T lymphocytes than immunization with a single vector. The results obtained using experimental models have led to clinical vaccination trials that are currently underway.Parasitas intracelulares obrigatórios como Plasmodium sp, Trypanosoma cruzi, Toxoplasma gondii e Leishmania sp são responsáveis pela infecção de milhões de indivíduos a cada ano. Estes parasitas são capazes de liberar antígenos no citoplasma de células infectadas do hospedeiro que são apresentados por moléculas de MHC classe I para células T CD8 protetoras. As condições de estímulo in vivo destas células T CD8 específicas durante a infecção natural são pouco conhecidas e constituem uma área pouco explorada. Os mecanismos anti-parasitários mediados por células T CD8 incluem vias dependentes e independentes do interferon-g. O fato que células T CD8 são potentes inibidores do desenvolvimento parasitário levou diversos investigadores a explorarem se a indução destes linfócitos T poderia constituir uma estratégia factível para o desenvolvimento de vacinas efetivas contra estas doenças parasitárias. Estudos feitos em modelos experimentais suportam a hipótese que células T CD8 induzidas por vetores recombinantes virais ou vacinas de DNA podem servir de base para a vacinação humana. Regimes de imunização consistindo de dois vetores distintos (prime-boost heterólogo) são muito mais eficientes em termos da expansão de linfócitos T CD8 protetores do que a imunização com um único vetor. Os resultados obtidos usando modelos experimentais levaram a vacinações clínicas que estão atualmente em curso.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de Microbiologia, Imunologia e ParasitologiaUniversidade de São Paulo Faculdade de Ciências Farmacêuticas Departamento de Análises Clínicas e ToxicológicasUNIFESP, EPM, Depto. de Microbiologia, Imunologia e ParasitologiaSciEL

Comparative recognition by human IgG antibodies of recombinant proteins representing three asexual erythrocytic stage vaccine candidates of Plasmodium vivax

In previous immuno-epidemiological studies of the naturally acquired antibody responses to merozoite surface protein-1 (MSP-1) of Plasmodium vivax, we had evidence that the responses to distinct erythrocytic stage antigens could be differentially regulated. The present study was designed to compare the antibody response to three asexual erythrocytic stage antigens vaccine candidates of P. vivax. Recombinant proteins representing the 19 kDa C-terminal region of MSP-1(PvMSP19), apical membrane antigen n-1 ectodomain (PvAMA-1), and the region II of duffy binding protein (PvDBP-RII) were compared in their ability to bind to IgG antibodies of serum samples collected from 220 individuals from the state of Pará, in the North of Brazil. During patent infection with P. vivax, the frequency of individuals with IgG antibodies to PvMSP1(19), PvAMA-1, and PvDBP-RII were 95, 72.7, and 44.5% respectively. Although the frequency of responders to PvDBP-RII was lower, this frequency increased in individuals following multiple malarial infections. Individually, the specific antibody levels did not decline significantly nine months after treatment, except to PvMSP1(19). Our results further confirm a complex regulation of the immune response to distinct blood stage antigens. The reason for that is presently unknown but it may contribute to the high risk of re-infection in individuals living in the endemic areas.Universidade de São Paulo Faculdade de Ciências Farmacêuticas Departamento de Análises Clínicas e ToxicológicasUniversidade Federal do Pará Centro de Ciências Biológicas Departamento de PatologiaInternational Centre for Genetic Engineering and Biotechnology Centro de Ciências Biológicas Malaria Research GroupUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de Microbiologia, Imunologia e ParasitologiaUNIFESP, EPM, Depto. de Microbiologia, Imunologia e ParasitologiaSciEL

To B or Not to B: Understanding B Cell Responses in the Development of Malaria Infection

Malaria is a widespread disease caused mainly by the Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) protozoan parasites. Depending on the parasite responsible for the infection, high morbidity and mortality can be triggered. To escape the host immune responses, Plasmodium parasites disturb the functionality of B cell subsets among other cell types. However, some antibodies elicited during a malaria infection have the potential to block pathogen invasion and dissemination into the host. Thus, the question remains, why is protection not developed and maintained after the primary parasite exposure? In this review, we discuss different aspects of B cell responses against Plasmodium antigens during malaria infection. Since most studies have focused on the quantification of serum antibody titers, those B cell responses have not been fully characterized. However, to secrete antibodies, a complex cellular response is set up, including not only the activation and differentiation of B cells into antibody-secreting cells, but also the participation of other cell subsets in the germinal center reactions. Therefore, a better understanding of how B cell subsets are stimulated during malaria infection will provide essential insights toward the design of potent interventions

Comparison of the human immune responses to recombinant proteins representing three distinct surface proteins of Plasmodium vivax merozoites

Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM) Departamento de Microbiologia, Imunologia e ParasitologiaUniversidade Federal do Pará Departamento de PatologiaCenters for Disease Control and Prevention Division of Parasitic DiseasesInstituto Evandro ChagasUniversidade Federal de Minas Gerais Departamento de ParasitologiaUNIFESP, EPM, Depto. de Microbiologia, Imunologia e ParasitologiaSciEL

A Birth Cohort Study

Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.BACKGROUND: Relatively few Amazonian infants have clinical malaria diagnosed, treated and notified before their first birthday, either because they are little exposed to an infection or remain asymptomatic once infected. Here we measure the proportion of children who have experienced Plasmodium vivax infection and malaria by 2 years of age in the main transmission hotspot of Amazonian Brazil. METHODS: We measured IgG antibodies to 3 blood-stage P. vivax antigens at the 1- and 2-year follow-up assessment of 435 participants in a population-based birth cohort. Children's malaria case notifications were retrieved from the electronic database of the Ministry of Health. We used multiple Poisson regression models to identify predictors of serologically proven P. vivax infection and clinical vivax malaria during the first 2 years of life. RESULTS: Overall, 23 [5.3%; 95% confidence interval (CI): 3.5-7.8%) children had antibodies to ≥2 antigens detected during at least one follow-up assessment, consistent with past P. vivax infection(s). Fifteen (3.4%; 95% CI: 2.1-5.6%) children had clinical vivax episodes notified during the first 2 years of life; 7 of them were seronegative. We estimate that half of the infections remained unnotified. Children born to women who experienced P. vivax infection during pregnancy were more likely to be infected and develop clinical vivax malaria, while those breast-fed for ≥12 months had their risk of being P. vivax-seropositive (which we take as evidence of blood-stage P. vivax infection during the first 2 years of life) decreased by 79.8% (95% CI: 69.3-86.7%). CONCLUSION: P. vivax infections in early childhood are underreported in the Amazon, are associated with anemia at 2 years of age, and appear to be partially prevented by prolonged breastfeeding.publishersversionepub_ahead_of_prin

Pharmaceutical intervention in medicine related problems in hospital: a pilot study performed in a hospital of south Brasil

O objetivo deste estudo foi detectar problemas relacionados aos medicamentos (PRM) e avaliar a aceitabilidade das intervenções farmacêuticas pelos médicos. Este estudo foi realizado em um hospital geral do Sul de Santa Catarina, Brasil. Todos os pacientes (27) investigados tomaram mais de 5 medicamentos (média 8,3 ± 2,8). 27,5 % dos medicamentos utilizados foram agentes do sistema nervoso central, 25,7 % foram agentes cardiovasculares, 17,1 % dos medicamentos foram usados para afetar a coagulação do sangue e tratamento de anemias e 14,9 % medicamentos que atuam sobre o trato gastrointestinal. Foram realizadas 31 intervenções farmacêuticas relacionadas com PRM (87,1 %) e necessidade de exames ou diagnósticos complementares (12,9 %). 63,0 % dos PRM relacionados foram manifestados. 48,0 % das intervenções farmacêuticas aceitas foram relacionados a PRM. Ficou claro que os PRM em pacientes polimedicados podem ser identificados por farmacêuticos mostrando o seu papel no uso racional de medicamentos em ambiente hospitalar.The aim of this study was to detect medicine-related problems (MRP) and to evaluate physicians' acceptability of pharmaceutical interventions. This study was conducted in a general hospital in southern Santa Catarina, Brazil. All patients (27) investigated took more than 5 medications (mean 8.3 ± 2.8). 27.5 % of the medications used were central nervous system agents, 25.7 % were cardiovascular agents, 17.1 % were drugs used to affect blood clotting and agents used in anemia, and 14.9 % were drugs that act on the gastrointestinal tract. 31 pharmaceutical interventions were performed related to MRP (87.1 %) and to complementary diagnostic exams (12.9 %). 63.0 % of the listed MRP were reported. 48.0 % of the pharmaceutical interventions accepted by the physicians were related to MRP. It was clear that MRP in polymedicated patients can be identified by pharmacists, playing their role in promoting the rational use of medicines in hospital settings.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Pharmaceutical intervention in medicine related problems in hospital: a pilot study performed in a hospital of south Brasil

O objetivo deste estudo foi detectar problemas relacionados aos medicamentos (PRM) e avaliar a aceitabilidade das intervenções farmacêuticas pelos médicos. Este estudo foi realizado em um hospital geral do Sul de Santa Catarina, Brasil. Todos os pacientes (27) investigados tomaram mais de 5 medicamentos (média 8,3 ± 2,8). 27,5 % dos medicamentos utilizados foram agentes do sistema nervoso central, 25,7 % foram agentes cardiovasculares, 17,1 % dos medicamentos foram usados para afetar a coagulação do sangue e tratamento de anemias e 14,9 % medicamentos que atuam sobre o trato gastrointestinal. Foram realizadas 31 intervenções farmacêuticas relacionadas com PRM (87,1 %) e necessidade de exames ou diagnósticos complementares (12,9 %). 63,0 % dos PRM relacionados foram manifestados. 48,0 % das intervenções farmacêuticas aceitas foram relacionados a PRM. Ficou claro que os PRM em pacientes polimedicados podem ser identificados por farmacêuticos mostrando o seu papel no uso racional de medicamentos em ambiente hospitalar.The aim of this study was to detect medicine-related problems (MRP) and to evaluate physicians' acceptability of pharmaceutical interventions. This study was conducted in a general hospital in southern Santa Catarina, Brazil. All patients (27) investigated took more than 5 medications (mean 8.3 ± 2.8). 27.5 % of the medications used were central nervous system agents, 25.7 % were cardiovascular agents, 17.1 % were drugs used to affect blood clotting and agents used in anemia, and 14.9 % were drugs that act on the gastrointestinal tract. 31 pharmaceutical interventions were performed related to MRP (87.1 %) and to complementary diagnostic exams (12.9 %). 63.0 % of the listed MRP were reported. 48.0 % of the pharmaceutical interventions accepted by the physicians were related to MRP. It was clear that MRP in polymedicated patients can be identified by pharmacists, playing their role in promoting the rational use of medicines in hospital settings.Colegio de Farmacéuticos de la Provincia de Buenos Aire