Assembling the layers of the hematopoietic system: A window of opportunity for thymopoiesis in the embryo.

During embryonic development, several independent generations of hematopoietic cells were identified. They occur in the yolk sac and the intra-embryonic major arteries, in a narrow window of development. They arise sequentially, starting with primitive erythrocytes in the yolk sac blood islands, progressing to less differentiated erythromyeloid progenitors still in the yolk sac, and culminating with multipotent progenitors, some of which will generate the adult hematopoietic stem cell compartment. All these cells contribute to the formation of a layered hematopoietic system that reflects adaptative strategies to the fetal environment and the embryo's needs. It is mostly composed, at these stages, of erythrocytes and tissue-resident macrophages both of yolk sac origin, the latter persisting throughout life. We propose that subsets of lymphocytes of embryonic origin derive from a different intra-embryonic generation of multipotent cells occurring before the emergence of hematopoietic stem cell progenitors. These multipotent cells have a limited lifespan and generate cells that provide basic protection against pathogens before the adaptive immune system is functional, contribute to tissue development and homeostasis, and shape the establishment of a functional thymus. Understanding the properties of these cells will impact the understanding of childhood leukemia and of adult autoimmune pathology and thymic involution.

Reabilitação funcional e barreiras para atividade física na COVID-longa: um ensaio clínico randomizado / Functional rehabilitation and barriers to physical activity after COVID-19: a randomized clinical trial

O estudo teve como objetivo analisar as barreiras percebidas à prática de atividade física durante um programa de treinamento multicomponente em adultos e idosos pós infecção por COVID-19. Realizou-se um ensaio clínico randomizado com 40 participantes (19 grupo controle e 21 grupo intervenção). Foram coletadas informações sociodemográficas, de saúde e de barreiras para a prática de atividade física, antes, 12 e 24 semanas após o início da intervenção. A medida das barreiras para a prática de atividade física foi obtida por meio de uma escala válida composta por 16 itens. As diferen-ças de barreiras entre os grupos e ao longo de tempo foi analisada a partir das Equações de Estimativa Generalizada, α = 0,05. As barreiras mais citadas pelos dois grupos na linha de base foram "Preguiça, cansaço ou desânimo" (71%), "Dores, lesões ou incapacidade" (38%) e "Falta de motivação" (48%). As análises principais indicaram que ambos os grupos tiveram redução na frequência da barreira "Pre-guiça, cansaço ou desânimo" na 12ª semana (p = 0,003), porém voltando aos valores iniciais na 24ª semana (p = 0,441). Já a barreira "Por causa da epidemia de coronavírus" foi reduzida na 12ª semana (p = 0,704) e ainda mais reduzida na 24ª semana (p = 0,158), comportamento também similar entre os grupos. Como principal conclusão, barreiras para atividade física podem ser reduzidas pela parti-cipação em programas de exercício supervisionado e recomendação para a prática de atividade física

The study aimed to analyze perceived barriers to physical activity during a multicomponent training pro-gram in adults and seniors post-COVID-19 infection. A randomized clinical trial was conducted with 40 participants (19 control group and 21 intervention group). Sociodemographic, health, and barriers to physical activity information were collected before, 12 and 24 weeks after the start of the intervention. The measure of barriers to physical activity was obtained through a valid scale composed of 16 items. Differences in barriers between groups and over time were analyzed using Generalized Estimating Equations, α = 0.05. The most frequently mentioned barriers at baseline by both groups were "Laziness, fatigue, or lack of enthusiasm" (71%), "Pain, injuries, or disability" (38%), and "Lack of motivation" (48%). The main analyses indicated that both groups had a reduction in the frequency of the barrier "Laziness, fatigue, or lack of enthusiasm" at week 12 (p = 0.003), but returned to initial values at week 24 (p = 0.441). The barrier "Because of the coronavirus epidemic" was reduced in week 12 (p = 0.704) and further reduced in week 24 (p = 0.158), with a similar pattern between groups. The key conclusion is that barriers to physical activity can be reduced through participation in supervised exercise programs and recommendations for physical activity

Genomic monitoring unveils a high prevalence of severe acute respiratory syndrome coronavirus 2 Omicron variant in vaccine breakthrough cases in Bahia, Brazil

SUMMARY OBJECTIVE: Genome sequencing has been proved to be an excellent tool to monitor the molecular epidemiology of the disease caused by severe acute respiratory syndrome coronavirus 2, i.e., coronavirus disease 2019. Some reports of infected, vaccinated individuals have aroused great interest because they are primarily being infected with circulating variants of concern. To investigate the cases of infected, vaccinated individuals in Salvador, Bahia, Brazil, we performed genomic monitoring to estimate the magnitude of the different variants of concern in these cases. METHODS: Nasopharyngeal swabs from infected (symptomatic and asymptomatic), vaccinated or unvaccinated individuals (n=29), and quantitative reverse transcription polymerase chain reaction cycle threshold value (Ct values) of ≤30 were subjected to viral sequencing using nanopore technology. RESULTS: Our analysis revealed that the Omicron variant was found in 99% of cases and the Delta variant was found in only one case. Infected, fully vaccinated patients have a favorable clinical prognosis; however, within the community, they become viral carriers with the aggravating factor of viral dissemination of variants of concern not neutralized by the currently available vaccines. CONCLUSION: It is important to acknowledge the limitations of these vaccines and to develop new vaccines to emergent variants of concern, as is the case of influenza vaccine; going through new doses of the same coronavirus vaccines is "more of the same."

Interleukin-10 induces interferon-γ-dependent emergency myelopoiesis.

In emergency myelopoiesis (EM), expansion of the myeloid progenitor compartment and increased myeloid cell production are observed and often mediated by the pro-inflammatory cytokine interferon gamma (IFN-γ). Interleukin-10 (IL-10) inhibits IFN-γ secretion, but paradoxically, its therapeutic administration to humans causes hematologic changes similar to those observed in EM. In this work, we use different in vivo systems, including a humanized immune system mouse model, to show that IL-10 triggers EM, with a significant expansion of the myeloid progenitor compartment and production of myeloid cells. Hematopoietic progenitors display a prominent IFN-γ transcriptional signature, and we show that IFN-γ mediates IL-10-driven EM. We also find that IL-10, unexpectedly, reprograms CD4 and CD8 T cells toward an activation state that includes IFN-γ production by these T cell subsets in vivo. Therefore, in addition to its established anti-inflammatory properties, IL-10 can induce IFN-γ production and EM, opening additional perspectives for the design of IL-10-based immunotherapies.

NK Cell Responses in Zika Virus Infection Are Biased towards Cytokine-Mediated Effector Functions.

Zika virus (ZIKV) is a mosquito-borne flavivirus that has emerged as a global concern because of its impact on human health. ZIKV infection during pregnancy can cause microcephaly and other severe brain defects in the developing fetus and there have been reports of the occurrence of Guillain-Barré syndrome in areas affected by ZIKV. NK cells are activated during acute viral infections and their activity contributes to a first line of defense because of their ability to rapidly recognize and kill virus-infected cells. To provide insight into NK cell function during ZIKV infection, we have profiled, using mass cytometry, the NK cell receptor-ligand repertoire in a cohort of acute ZIKV-infected female patients. Freshly isolated NK cells from these patients contained distinct, activated, and terminally differentiated, subsets expressing higher levels of CD57, NKG2C, and KIR3DL1 as compared with those from healthy donors. Moreover, KIR3DL1+ NK cells from these patients produced high levels of IFN-γ and TNF-α, in the absence of direct cytotoxicity, in response to in vitro stimulation with autologous, ZIKV-infected, monocyte-derived dendritic cells. In ZIKV-infected patients, overproduction of IFN-γ correlated with STAT-5 activation (r = 0.6643; p = 0.0085) and was mediated following the recognition of MHC class 1-related chain A and chain B molecules expressed by ZIKV-infected monocyte-derived dendritic cells, in synergy with IL-12 production by the latter cells. Together, these findings suggest that NK cells contribute to the generation of an efficacious adaptive anti-ZIKV immune response that could potentially affect the outcome of the disease and/or the development of persistent symptoms.

Óbitos por Covid -19 no estado da Bahia: da captação à publicação / Deaths by Covid -19 in the state of Bahia: from capture to publication / Muertes por Covid -19 en el estado de Bahía: desde la captura hasta la publicación

Identificada inicialmente em Wuhan, na China, a Covid-19 causada pelo novo coronavírus da síndrome respiratória (SARS-CoV-2) provocou um alerta global. Diante desse cenário emergencial, o Brasil, assim como outros países, tem vivenciando grandes mudanças nas ações e serviços em saúde. Na Bahia, a velocidade de disseminação da doença ocasionou um aumento significativo na notificação de casos e óbitos, promovendo uma restruturação no processo de trabalho da vigilância epidemiológica estadual para atuar de forma oportuna na captação, investigação e classificação de casos, e publicação e recomendações de medidas sanitárias. Este trabalho objetiva descrever o processo de trabalho na vigilância epidemiológica de óbitos por Covid-19 no estado da Bahia. Trata-se de um relato de experiência do processo de trabalho de análise dos óbitos por Covid-19 no período de março a dezembro de 2020. A trajetória metodológica foi estruturada em análise documental, relatórios de investigação, ferramentas de notificação do Ministério da Saúde e outros sistemas oficiais, como o Formulário Eletrônico do SUS ­ FormSUS, produzido pela Diretoria de Vigilância Epidemiológica para identificar os óbitos por Covid-19 nos hospitais da Bahia em tempo hábil, facilitando o processo de captação, investigação, análise e publicação de informação de mortalidade. Observou-se que a estruturação de um processo organizado e aplicado ao fluxo de trabalho possibilitou a qualificação e a fidedignidade das informações dos óbitos por Covid-19, garantindo mudanças incrementais no âmbito da vigilância e segurança das informações publicadas, essenciais para o planejamento das ações de prevenção e controle.

Initially identified in Wuhan, China, Covid-19 caused by the respiratory syndrome coronavirus (SARS-CoV-2) has triggered a global alert. Faced with this emergency scenario, Brazil, like other countries, has been experiencing major changes in health actions and services. In the state of Bahia, the rapid spread of the disease increased significantly the notification of cases and deaths, promoting a restructuring in the work process of state epidemiological surveillance to act in a timely manner in capturing, investigating and classifying cases, publishing and recommending sanitary measures. This paper aims at describing the work process in the epidemiological surveillance of deaths by Covid-19 in the state of Bahia. This is an experience report of Covid-19 death analysis work process, from March to December 2020. The methodological trajectory was structured in document analysis, investigation reports, notification tools from the Ministry of Health and others official systems, and the SUS FormSUS Electronic Form, produced by the Epidemiological Surveillance Directorate (Divep) to identify deaths by Covid-19 by hospitals in Bahia in a timely manner, facilitating the process of capturing, investigating, analyzing and publishing information of mortality. It was observed that the structuring of an organized process and application to the workflow enabled the qualification and reliability of death information by Covid-19, ensuring incremental changes in the scope of surveillance and security in the published information, essential for planning prevention and control actions.

Inicialmente identificado en Wuhan, China, el covid-19 causante del síndrome respiratorio agudo grave (SARS-CoV-2) ha desencadenado una alerta global. Ante este escenario de emergencia, Brasil, al igual que otros países, ha venido experimentando importantes cambios en las acciones y servicios de salud. En Bahía, la velocidad de propagación de la enfermedad provocó un aumento significativo en la notificación de casos y defunciones, promoviendo una reestructuración en el proceso de trabajo de la vigilancia epidemiológica estadual para actuar de manera oportuna en la recopilación, investigación, clasificación de casos, publicación y recomendación de medidas preventivas. Este artículo tiene como objetivo describir el proceso de trabajo en la vigilancia epidemiológica de las muertes por covid-19 en el estado de Bahía. Es un informe de experiencia del proceso de trabajo de análisis de muertes por covid-19, de marzo a diciembre de 2020. La trayectoria metodológica se estructuró en análisis de documentos, informes de investigación, herramientas de notificación del Ministerio de Salud y otros sistemas oficiales, así como el Formulario Electrónico SUS FormSUS, elaborado por la Dirección de Vigilancia Epidemiológica (Divep) para identificar las muertes por covid-19 en los hospitales de Bahía de manera oportuna, lo que facilita el proceso de recopilación, investigación, análisis y publicación de información sobre mortalidad. Se observó que la estructuración de un proceso organizado y aplicado al flujo de trabajo permitió la calificación y confiabilidad de la información de muertes por covid-19, asegurando cambios incrementales en el alcance de la vigilancia y seguridad de la información publicada, fundamental para planificar la prevención y el control.

A wave of bipotent T/ILC-restricted progenitors shapes the embryonic thymus microenvironment in a time-dependent manner.

During embryonic development, multiple waves of hematopoietic progenitors with distinct lineage potential are differentially regulated in time and space. Two different waves of thymic progenitors colonize the fetal thymus where they contribute to thymic organogenesis and homeostasis. The origin, the lineage differentiation potential of the first wave, and their relative contribution in shaping the thymus architecture, remained, however, unclear. Here, we show that the first wave of thymic progenitors comprises a unique population of bipotent T and innatel lymphoid cells (T/ILC), generating a lymphoid tissue inducer cells (LTi's), in addition to invariant Vγ5+ T cells. Transcriptional analysis revealed that innate lymphoid gene signatures and, more precisely, the LTi-associated transcripts were expressed in the first, but not in the second, wave of thymic progenitors. Depletion of early thymic progenitors in a temporally controlled manner showed that the progeny of the first wave is indispensable for the differentiation of autoimmune regulator-expressing medullary thymic epithelial cells (mTECs). We further show that these progenitors are of strict hematopoietic stem cell origin, despite the overlap between lymphopoiesis initiation and the transient expression of lymphoid-associated transcripts in yolk sac (YS) erythromyeloid-restricted precursors. Our work highlights the relevance of the developmental timing on the emergence of different lymphoid subsets, required for the establishment of a functionally diverse immune system.

Clinical and laboratory findings of acute Zika virus infection in patients from Salvador during the first Brazilian epidemic

Abstract Several major epidemics of Zika fever, caused by the ZIKA virus (ZIKV), have emerged in Brazil since early 2015, eventually spreading to other countries on the South American continent. The present study describes the clinical manifestations and laboratory findings of patients with confirmed acute ZIKV infection during the first epidemic that occurred in Salvador, Brazil. All included patients were seen at the emergency room of a private tertiary hospital located in Salvador, Brazil from 2015 through 2017. Patients were considered eligible if signs of systemic viral febrile disease were present. All individuals were tested for ZIKV and Chikungunya infection using PCR, while rapid test was used to detect Dengue virus antibodies or, alternatively, the NS1 antigen. A diagnosis of acute ZIKV infection was confirmed in 78/434 (18%) individuals with systemic viral febrile illness. Positivity was mainly observed in blood, followed by saliva and urine. Coinfection with Chikungunya and/or Dengue virus was detected in 5% of the ZIKV-infected patients. The most frequent clinical findings were myalgia, arthralgia and low-grade fever. Laboratory analysis demonstrated normal levels of hematocrit, platelets and liver enzymes. In summary, in acute settings where molecular testing remains unavailable, clinicians face difficulties to confirm the diagnosis of ZIKV infection, as they rely only on clinical examinations and conventional laboratory tests.

Hematopoiesis: A Layered Organization Across Chordate Species.

The identification of distinct waves of progenitors during development, each corresponding to a specific time, space, and function, provided the basis for the concept of a "layered" organization in development. The concept of a layered hematopoiesis was established by classical embryology studies in birds and amphibians. Recent progress in generating reliable lineage tracing models together with transcriptional and proteomic analyses in single cells revealed that, also in mammals, the hematopoietic system evolves in successive waves of progenitors with distinct properties and fate. During embryogenesis, sequential waves of hematopoietic progenitors emerge at different anatomic sites, generating specific cell types with distinct functions and tissue homing capacities. The first progenitors originate in the yolk sac before the emergence of hematopoietic stem cells, some giving rise to progenies that persist throughout life. Hematopoietic stem cell-derived cells that protect organisms against environmental pathogens follow the same sequential strategy, with subsets of lymphoid cells being only produced during embryonic development. Growing evidence indicates that fetal immune cells contribute to the proper development of the organs they seed and later ensure life-long tissue homeostasis and immune protection. They include macrophages, mast cells, some γδ T cells, B-1 B cells, and innate lymphoid cells, which have "non-redundant" functions, and early perturbations in their development or function affect immunity in the adult. These observations challenged the view that all hematopoietic cells found in the adult result from constant and monotonous production from bone marrow-resident hematopoietic stem cells. In this review, we evaluate evidence for a layered hematopoietic system across species. We discuss mechanisms and selective pressures leading to the temporal generation of different cell types. We elaborate on the consequences of disturbing fetal immune cells on tissue homeostasis and immune development later in life.

Síndrome de leigh: a propósito de um caso clínico com mutação no dna mitocondrial / Leigh syndrome: a case report with a mitochondrial dna mutation

RESUMO Objetivo: A síndrome de Leigh é uma doença neurodegenerativa com incidência de 1:40.000 nados-vivos. Apresenta ampla heterogeneidade clínica, bioquímica e genética, mas com alterações neuropatorradiológicas homogêneas. Não existe tratamento específico, e o prognóstico é reservado. O objetivo deste estudo foi familiarizar os profissionais de saúde com a doença. Descrição do caso: Menina de 16 meses, com hipotonia axial e atraso do desenvolvimento psicomotor. Dos exames realizados: cariótipo, potenciais auditivos evocados e avaliação oftalmológica normais; presença de hiperlactacidemia e hipocitrulinemia. Após a realização de ressonância magnética cerebral sob anestesia, observou-se agravamento da hipotonia com necessidade de internação por episódios de cianose/apneia. O eletroencefalograma não mostrou atividade epileptiforme. A neuroimagem revelou hipersinal lenticular bilateral com lesão do putâmen e do globo pálido esquerdo. Encontrou-se a mutação 8993T>G (MT-ATP6) no DNA mitocondrial. Comentários: De 10 a 30% dos doentes com síndrome de Leigh apresentam mutações do DNA mitocondrial. A descompensação com agravamento neurológico após intervenção anestésica está descrita e, nesse caso, apoiou o diagnóstico. Importante alertar para casos semelhantes, com diminuição de exames invasivos para diagnóstico.

ABSTRACT Objective: Leigh syndrome is a neurodegenerative disorder with an incidence of 1:40,000 live births. It presents wide clinical, biochemical, and genetic heterogeneity, but with homogenous neuropatoradiological alterations. There is no specific treatment, and the prognosis is reserved. This case report aimed familiarize health professionals with the disease. Case Description: A 16-month-hold girl who was followed in outpatient clinic due to axial hypotonia and delayed psychomotor development. Karyotype, auditory evoked potentials and ophthalmologic evaluation were normal. Evidence of hyperlactacidemia and hypocitrullinemia was detected in the patient. After performing brain magnetic resonance under anesthesia, hypotonia got worse, and the patient was hospitalized after an episode of cyanosis and apnea. The electroencephalogram showed no epileptiform activity. Neuroimaging revealed bilateral lenticular hyperintensity, especially in the putamen and in the left globus pallidus regions. Molecular analysis revealed an 8993T>G (MT-ATP6) mutation in the mitochondrial DNA. Comments: Between 10 and 30% of individuals with Leigh syndrome have mitochondrial DNA mutations. The decompensation after anesthetic intercurrences is typically associated with neurological deterioration and, in this case, increased the diagnosis suspicion. It is important to alert for similar cases and to reduce invasive diagnostic tests if the diagnosis is suspected.

Antiretroviral changes during the first year of therapy / Mudanças de terapia antirretroviral durante o primeiro ano de tratamento

Summary Introduction: The Brazilian HIV/AIDS management and treatment guideline (PCDT), published in 2013, recommends and standardizes the use of highly active antiretroviral therapy (HAART) in all adult patients, in spite of LTCD4 count. This study aimed to analyze the first year of HAART use in patients from a reference center on HIV/AIDS management in Fortaleza, Ceará. Method: This descriptive study reviewed all prescription forms of antiretroviral regimens initiation and changes from January to July 2014. All antiretroviral regimen changes that occurred during the first year of therapy were evaluated. Data were analyzed with SPSS version 20. Mean, standard deviation and frequency, Student's t and Mann-Whitney tests calculations were used, with significance at p<0.05. Results: From 527 patients initiating HAART, 16.5% (n=87) had a regimen change in the first year. These patients were mostly male (59.8%; n=52), aged 20 to 39 years, with only one HAART change (72.4%; n=63). Efavirenz was the most often changed drug, followed by tenofovir, zidovudine and lopinavir/ritonavir. Mean time of HAART changes was 120 days, with adverse reactions as the most prevalent cause. HAART was effective in decreasing viral load since second month of treatment (p=0.003) and increasing LTCD4 lymphocytes since fifth month (p<0.001). Conclusion: The main cause of initial HAART changes was adverse reaction and most patients had only one change in the HAART regimen. HAART prescription was in accordance to the PCDT from 2013.

Resumo Introdução: O Protocolo Clínico e Diretrizes Terapêuticas para manejo da infecção pelo HIV em adultos (PCDT) de 2013 recomenda e normatiza início de terapia antirretroviral (TARV) em pacientes com qualquer contagem de LTCD4. O objetivo do estudo foi analisar o primeiro ano de TARV de pacientes em acompanhamento em um centro de referência em HIV/AIDS de Fortaleza, Ceará. Método: O estudo descritivo revisou formulários de solicitação de início e modificação de TARV em pacientes que iniciaram tratamento entre janeiro e julho de 2014. Foram avaliadas todas as mudanças que ocorreram durante o primeiro ano de terapia. Os dados foram analisados no programa Statistical Package for the Social Sciences (SPSS) versão 20. Foram calculados médias, desvios padrão, frequências, testes t Student e Mann-Whitney, com significância de p<0,05. Resultados: Dos 527 pacientes que iniciaram TARV, 16,5% (n=87) realizaram troca no primeiro ano. A maioria era do sexo masculino (59,8%; n=52), de 20 a 39 anos, com apenas uma mudança da TARV (72,4%; n=63). Efavirenz foi o fármaco mais substituído, seguido por tenofovir, zidovudina e lopinavir/ritonavir. O tempo médio de ocorrência das modificações da TARV foi de 120 dias, tendo reações adversas como causas principais. TARV foi efetiva na queda da carga viral desde o 2ºmês de tratamento (p=0,003) e na elevação de LTCD4 desde o 5º mês (p<0,001). Conclusão: Os principais fatores envolvidos em modificações de TARV inicial foram reações adversas, com apenas uma mudança de esquema na maioria dos pacientes. O manejo da TARV estava de acordo com o PCDT de 2013.

Zika virus infection induces mitosis abnormalities and apoptotic cell death of human neural progenitor cells.

Zika virus (ZIKV) infection has been associated with severe complications both in the developing and adult nervous system. To investigate the deleterious effects of ZIKV infection, we used human neural progenitor cells (NPC), derived from induced pluripotent stem cells (iPSC). We found that NPC are highly susceptible to ZIKV and the infection results in cell death. ZIKV infection led to a marked reduction in cell proliferation, ultrastructural alterations and induction of autophagy. Induction of apoptosis of Sox2+ cells was demonstrated by activation of caspases 3/7, 8 and 9, and by ultrastructural and flow cytometry analyses. ZIKV-induced death of Sox2+ cells was prevented by incubation with the pan-caspase inhibitor, Z-VAD-FMK. By confocal microscopy analysis we found an increased number of cells with supernumerary centrosomes. Live imaging showed a significant increase in mitosis abnormalities, including multipolar spindle, chromosome laggards, micronuclei and death of progeny after cell division. FISH analysis for chromosomes 12 and 17 showed increased frequency of aneuploidy, such as monosomy, trisomy and polyploidy. Our study reinforces the link between ZIKV and abnormalities in the developing human brain, including microcephaly.

Regulatory T cells may participate in Helicobacter pylori persistence in gastric MALT lymphoma: lessons from an animal model.

It has been postulated that the emergence of autoimmune gastritis in neonatal thymectomised (d3Tx) BALB/c mice may be a consequence of post-surgery deficit in Tregs. In this study, previously obtained samples from d3Tx mice were used in order to determine whether thymectomy creates a deficit in this T cell subset thereby allowing the emergence of autoimmune phenomena as a prerequisite for GML. The splenic Treg reserve and the local recruitment of these cells in the gastric mucosa were investigated using complementary molecular and immunohistochemistry approaches. Higher Foxp3/CD3 ratios were found in the spleen of non-infected d3Tx mice compared to non-thymectomised (NTx) controls. These results indicate a relative enrichment of Tregs following thymectomy in adult mice. The absence of Treg depletion in d3Tx mice is in line with the absence of auto-immune gastritis in non-infected d3Tx mice. Higher levels of T cell and Treg infiltration were also found in the stomach of GML-developing d3Tx mice versus NTx mice. Surprisingly, inflammatory scores inversely correlated with the bacterial inoculum. The presence of a small Treg containing compartment among gastric biopsies of GML developing d3Tx mice may play a role in perseverance of a minimal bacterial numbers thereby maintaining an antigen-dependent stimulation and proliferation.

Neonatal thymectomy favors Helicobacter pylori-promoted gastric mucosa-associated lymphoid tissue lymphoma lesions in BALB/c mice.

Neonatal thymectomy in BALB/c mice has been described as a model of gastric mucosa-associated lymphoid tissue (MALT) lymphoma (GML). By using this experimental system, we screened, for the first time to our knowledge, Helicobacter pylori GML-associated strains for their capacity to promote disease. A cohort of BALB/c mice underwent thymectomy at day 3 after birth (d3Tx). Successful thymic ablation was evaluated by the degree of lymphopenia in blood samples collected at 4 weeks of age. d3Tx and non-thymectomized controls were infected with either GML strains (B38 or B47) or control strains (SS1 or TN2GF4). Gastric samples collected at 6, 12, and 18 months after infection were studied for bacteria content, and submitted to histological, immunochemical, molecular, and immunological analyses. Severe gastric inflammation was only observed in d3Tx mice. In these animals, the gastric lamina propria was infiltrated with lymphoid cells organized in follicles composed of B cells with few infiltrating T cells. PCR of D/J IgH gene segments proved the monoclonality of infiltrating B cells, which strongly correlated with the presence of lymphoepithelial lesions. B-cell infiltrates were particularly prominent in mice infected with the B47-GML strain. No pathological changes were detected in noninfected d3Tx mice. We identified new H. pylori isolates adapted to the mouse stomach with high potential of GML development, which is only revealed in hosts rendered lymphopenic by neonatal thymic ablation.

Origin, trafficking, and intraepithelial fate of gut-tropic T cells.

The small intestine epithelium (SI-Ep) harbors millions of unconventional (γδ and CD4(-) CD8(-) NK1.1(-) TCRαß) and conventional (CD8αß and CD4) T cells, designated intraepithelial lymphocytes (IELs). Here, we identified the circulating pool of SI-Ep-tropic T cells and studied their capacity to colonize the SI-Ep under steady-state conditions in SPF mice. Developmentally regulated levels of α4ß7 endowed recent thymic emigrants (RTEs) of unconventional types with higher SI-Ep tropism than their conventional homologues. SI-Ep-tropic RTEs, which in all lineages emerged naive, homed to the SI-Ep, but this environment was inadequate to stimulate them to cycle. In contrast, conventional and, unexpectedly, unconventional T cells, particularly Vγ7(+) (hallmark of γδ IELs), previously stimulated to cycle in the gut-associated lymphoid tissue (GALT), proliferated in the SI-Ep. Cycling unconventional SI-Ep immigrants divided far more efficiently than their conventional homologues, thereby becoming predominant. This difference impacted on acquisition of high Granzyme B content, which required extensive proliferation. In conclusion, SI-Ep-tropic T cells follow a thymus-SI-Ep or a GALT-SI-Ep pathway, the latter generating highly competitive immigrants that are the sole precursors of cytotoxic IELs. These events occur continuously as part of the normal IEL dynamics.

Mycobacterium bovis Bacillus Calmette-Guérin killed by extended freeze-drying reduces colitis in mice.

BACKGROUND & AIMS: Mycobacterium bovis Bacillus Calmette-Guérin (BCG), killed by extended freeze-drying (EFD), induces secretion of interleukin-10 and reduces lung inflammation in a mouse model of asthma. We investigated the effects of EFD BCG in mouse models of inflammatory bowel disease. METHODS: EFD BCG was administered subcutaneously to mice with colitis induced by dextran sodium sulfate (DSS), oxazolone, or adoptive transfer of CD4(+)CD45RB(high)Foxp3(-) T cells from C57Bl/6 Foxp3GFP mice to RAG2(-/-) mice. RESULTS: EFD BCG, administered either before induction of DSS and oxazolone colitis or after development of acute or chronic DSS-induced colitis, reduced symptom scores, loss of body weight, and inflammation. Although transfer of CD4(+)CD45RB(high)Foxp3(-) cells induced colitis in RAG2(-/-) mice, administration of EFD BCG at the time of the transfer converted Foxp3(-) T cells to Foxp3(+) T cells and the mice did not develop colitis. EFD BCG protected mice from colitis via a mechanism that required expansion of T regulatory cells and production of interleukin-10 and transforming growth factor ß. EFD BCG activated the retinoid X receptor (RXR)-α-peroxisome proliferator-activated receptor (PPAR)-γ heterodimer, blocked translocation of nuclear factor κB to the nucleus, and reduced colonic inflammation; it did not increase the number of colon tumors that formed in mice with chronic DSS-induced colitis. CONCLUSIONS: EFD BCG controls severe colitis in mice by expanding T regulatory cell populations and PPAR-γ and might be developed to treat patients with inflammatory bowel disease.

Placental malaria-associated suppression of parasite-specific immune response in neonates has no major impact on systemic CD4 T cell homeostasis.

In areas where Plasmodium falciparum is endemic, pregnancy is associated with accumulation of infected red blood cells (RBCs) in the placenta, a condition referred to as placental malaria (PM). Infants born to PM-positive mothers are at an increased risk of malaria, which is putatively related to the transplacental passage of parasite-derived antigens, with consequent tolerization of the fetal immune system. Here we addressed the impact of PM on the regulation of neonatal T cell responses. We found that the frequency of regulatory CD25(+) CD127(-/low) Foxp3(+) CD4(+) T cells was significantly decreased in neonates born to mothers with high levels of P. falciparum-induced placental inflammation, consisting mainly of primigravid mothers. However, at the individual level, the ratio between regulatory and effector (CD25(+) CD127(+) Foxp3(-)) CD4(+) T cells was unaffected by PM. In addition, parasite-induced CD4(+) T cell activation and production of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and IL-10 were strongly reduced in neonates born to PM-positive mothers. Thus, our results show that active PM at delivery is associated with a marked suppression of P. falciparum-specific cellular neonatal immune responses, affecting secretion of both pro- and anti-inflammatory cytokines. Additionally, our results suggest that, as in adults, effector and regulatory CD4(+) T cell populations are tightly coregulated in all neonates, irrespective of the maternal infection status.

The Ets-1 transcription factor controls the development and function of natural regulatory T cells.

Regulatory T cells (T reg cells) constitute a population of CD4(+) T cells that limits immune responses. The transcription factor Foxp3 is important for determining the development and function of T reg cells; however, the molecular mechanisms that trigger and maintain its expression remain incompletely understood. In this study, we show that mice deficient for the Ets-1 transcription factor (Ets-1(-/-)) developed T cell-mediated splenomegaly and systemic autoimmunity that can be blocked by functional wild-type T reg cells. Spleens of Ets-1(-/-) mice contained mostly activated T cells, including Th2-polarized CD4(+) cells and had reduced percentages of T reg cells. Splenic and thymic Ets-1(-/-) T reg cells expressed low levels of Foxp3 and displayed the CD103 marker that characterizes antigen-experienced T reg cells. Thymic development of Ets-1(-/-) T reg cells appeared intrinsically altered as Foxp3-expressing cells differentiate poorly in mixed fetal liver reconstituted chimera and fetal thymic organ culture. Ets-1(-/-) T reg cells showed decreased in vitro suppression activity and did not protect Rag2(-/-) hosts from naive T cell-induced inflammatory bowel disease. Furthermore, in T reg cells, Ets-1 interacted with the Foxp3 intronic enhancer and was required for demethylation of this regulatory sequence. These data demonstrate that Ets-1 is required for the development of natural T reg cells and suggest a role for this transcription factor in the regulation of Foxp3 expression.

Bacterial contamination in milk kitchens in pediatric hospitals in Salvador, Brazil

Milk may represent an important source of infectious agents to hospitalized pediatric patients. To describe the bacterial microflora isolated from the hands, stools, pharynx of all workers at milk kitchens in pediatric hospitals in the city of Salvador, Brazil, as well as in the formulas prepared by them, we carried out this cross-sectional study with all 91 workers from the 20 milk kitchens of all the public and private hospitals in Salvador, Brazil. Hand and pharynx swabs and stool samples were collected from all workers, as well as samples of the milk and formulas delivered by the kitchens. All samples were cultured for the detection of pathogenic and non-pathogenic bacteria. Pathogenic bacteria were isolated from 20 (22.0 percent) and 8 (8.8 percent) cultures of the hands and pharynx of the workers, respectively. No pathogenic bacteria were isolated from stool samples. Pathogenic bacteria were isolated from 17 (18.7 percent) milk samples. The prevalence of pathogenic bacteria in hand swabs was significantly higher in workers from public (37.8 percent) than from private (6.5 percent) hospitals (prevalence ratio [PR]=5.8; p<0.01). Pathogenic bacteria were isolated from two (4.4 percent) workers from public hospitals and six (13.0 percent) workers from private hospitals (PR=0.38; p=0.27). Pathogenic bacteria were isolated from 11 (24.4 percent) milk samples from public hospitals and 6 (13.0 percent) from private hospitals (PR=1.9; p=0.16). A high prevalence of contamination was found, mainly on the hands of workers on units for manipulation of milk. Preventive efforts should be intensified and focus primarily on effective hand washing and continuous work supervision.

Avaliação do conhecimento geral de médicos emergencistas de hospitais de Salvador - Bahia sobre o atendimento de vítimas com parada cardiorrespiratória / Assessment of the general knowledge of emergency physicians from the hospitals of the city of Salvador (Brazil) on the care of cardiac arrest patients

OBJETIVO: Identificar a proporção de médicos emergencistas com habilitação em cursos de imersão (SAVC - Suporte Avançado de Vida em Cardiologia e SAVT - Suporte Avançado de Vida no Trauma), relacionando variáveis: idade, sexo, especialidade médica, titulação e tipo de hospital com o grau de conhecimento teórico no atendimento de vítimas de parada cardiorrespiratória. MÉTODOS: Foram avaliados de forma consecutiva, de novembro/2003 a julho/2004, os emergencistas de hospitais públicos e privados da cidade de Salvador - Bahia, que voluntariamente aceitaram participar do estudo. Esses responderam a um questionário construído de informações das variáveis de interesse: perfil do profissional, realização ou não dos cursos de imersão SAVC e SAVT, avaliação cognitiva com 22 questões objetivas sobre ressuscitação cardiopulmonar. Calculou-se para cada participante um valor de acertos indicado como variável escore. Esse questionário foi validado a partir do resultado do escore dos instrutores do curso SAVC em Salvador - BA. RESULTADOS: Dos 305 médicos que responderam ao questionário, 83 (27,2 por cento) haviam realizado o curso SAVC, tendo como média da variável escore o valor de 14,9+3,0, comparada com os 215 médicos (70,5 por cento) que não o haviam feito e cuja média foi de 10,5+3,5 (p=0,0001). A média do escore dos 65 cardiologistas (21,5 por cento) foi de 14,1+3,3, comparada com os 238 médicos (78,5 por cento) que eram de outras especialidades, com média de 9,7+3,7(p=0,0001). Não foi identificada diferença da média do escore entre os médicos que haviam ou não realizado o curso SAVT (p=0,67). CONCLUSÃO: Na amostra avaliada, o conhecimento teórico sobre ressucitação cárdio-pulmonar (RCP) foi superior naqueles profissionais que realizaram o SAVC, diferente do que ocorreu naqueles que realizaram o SAVT. Os especialistas em Cardiologia que realizaram o SAVC demonstraram um conhecimento teórico superior, sobre o atendimento de vítimas de parada cárdio-respiratória (PCR), quando...

OBJECTIVE: To identify the proportion of emergency physicians certified in immersion courses (ACLS - Advanced Cardiac Life Support and ATLS - Advanced Trauma Life Support) correlating the variables of age, gender, medical specialty, academic title, and type of hospital with the level of theoretical knowledge on the care of Cardiac Arrest (CA) victims. METHODS: Emergency physicians from public and private hospitals of the city of Salvador, State of Bahia - Brazil, were consecutively evaluated from November, 2003 to July, 2004. They volunteered to participate in the study, and responded to a questionnaire consisting of information on the following variables of interest: professional profile, participation or not in ACLS and ATLS immersion courses, and cognitive assessment with 22 objective questions on Cardiopulmonary Resuscitation (CPR). A score of correct answers was calculated for each participant, and then designated as score variable. This questionnaire was validated based on the result of the score obtained by ACLS course instructors in Salvador, BA. RESULTS: Of the 305 physicians who responded to the questionnaire, 83 (27.2 percent) had attended the ACLS course and had a mean score variable of 14.9+3.0 compared with the 215 physicians (70.5 percent) who had not attended the course and whose mean was 10.5+ 3.5 (p=0.0001). The mean score of the 65 cardiologists (21.5 percent) was 14.1+3.3 compared with the mean of 9.7+3.7(p=0.0001) of the 238 physicians (78.5 percent) from other specialties. No difference was observed in the mean scores between physicians who had attended the ATLS course or not (p=0.67). CONCLUSION: In the sample studied, theoretical knowledge on CPR was higher among physicians who had attended the ACLS course, as opposed to those who had attended the ATLS course. Cardiologists who had attended the ACLS demonstrated a higher theoretical knowledge on the care of CA patients when compared to physicians from other specialties taken as whole - Internal...