RESUMO
Although mice normally enter labor when their ovaries stop producing progesterone (luteolysis), parturition can also be triggered in this species through uterus-intrinsic pathways potentially analogous to the ones that trigger parturition in humans. Such pathways, however, remain largely undefined in both species. Here, we report that mice deficient in innate type 2 immunity experienced profound parturition delays when manipulated endocrinologically to circumvent luteolysis, thus obliging them to enter labor through uterus-intrinsic pathways. We found that these pathways were in part driven by the alarmin IL-33 produced by uterine interstitial fibroblasts. We also implicated important roles for uterine group 2 innate lymphoid cells, which demonstrated IL-33-dependent activation prior to labor onset, and eosinophils, which displayed evidence of elevated turnover in the prepartum uterus. These findings reveal a role for innate type 2 immunity in controlling the timing of labor onset through a cascade potentially relevant to human parturition.
Assuntos
Interleucina-33 , Luteólise , Gravidez , Feminino , Camundongos , Animais , Humanos , Interleucina-33/metabolismo , Imunidade Inata , Miométrio/metabolismo , Linfócitos , Parto/metabolismoRESUMO
Vγ9Vδ2 T cells rapidly respond to phosphoantigens produced by Plasmodium falciparum in an innate-like manner, without prior antigen exposure or processing. Vδ2 T cells have been shown to inhibit parasite replication in vitro and are associated with protection from P. falciparum parasitemia in vivo. Although a marked expansion of Vδ2 T cells is seen after acute malaria infection in naïve individuals, repeated malaria causes Vδ2 T cells to decline both in frequency and in malaria-responsiveness, and to exhibit numerous transcriptional and phenotypic changes, including upregulation of the Fc receptor CD16. Here we investigate the functional role of CD16 on Vδ2 T cells in the immune response to malaria. We show that CD16+ Vδ2 T cells possess more cytolytic potential than their CD16- counterparts, and bear many of the hallmarks of mature NK cells, including KIR expression. Furthermore, we demonstrate that Vδ2 T cells from heavily malaria-exposed individuals are able to respond to opsonized P.falciparum-infected red blood cells through CD16, representing a second, distinct pathway by which Vδ2 T cells may contribute to anti-parasite effector functions. This response was independent of TCR engagement, as demonstrated by blockade of the phosphoantigen presenting molecule Butyrophilin 3A1. Together these results indicate that Vδ2 T cells in heavily malaria-exposed individuals retain the capacity for antimalarial effector function, and demonstrate their activation by opsonized parasite antigen. This represents a new role both for Vδ2 T cells and for opsonizing antibodies in parasite clearance, emphasizing cooperation between the cellular and humoral arms of the immune system.
Assuntos
Malária Falciparum/imunologia , Malária/imunologia , Receptores de IgG/imunologia , Linfócitos T/imunologia , Adulto , Criança , Pré-Escolar , Feminino , Proteínas Ligadas por GPI/imunologia , Proteínas Ligadas por GPI/metabolismo , Humanos , Imunidade , Lactente , Malária/sangue , Malária/parasitologia , Malária Falciparum/metabolismo , Malária Falciparum/parasitologia , Masculino , Pessoa de Meia-Idade , Parasitemia/imunologia , Plasmodium falciparum/crescimento & desenvolvimento , Plasmodium falciparum/metabolismo , Receptores de IgG/metabolismo , Subpopulações de Linfócitos T/imunologia , Linfócitos T/metabolismo , Uganda/epidemiologiaRESUMO
Recently, we identified in two individuals with intellectual disability (ID) different de novo mutations in DEAF1, which encodes a transcription factor with an important role in embryonic development. To ascertain whether these mutations in DEAF1 are causative for the ID phenotype, we performed targeted resequencing of DEAF1 in an additional cohort of over 2,300 individuals with unexplained ID and identified two additional individuals with de novo mutations in this gene. All four individuals had severe ID with severely affected speech development, and three showed severe behavioral problems. DEAF1 is highly expressed in the CNS, especially during early embryonic development. All four mutations were missense mutations affecting the SAND domain of DEAF1. Altered DEAF1 harboring any of the four amino acid changes showed impaired transcriptional regulation of the DEAF1 promoter. Moreover, behavioral studies in mice with a conditional knockout of Deaf1 in the brain showed memory deficits and increased anxiety-like behavior. Our results demonstrate that mutations in DEAF1 cause ID and behavioral problems, most likely as a result of impaired transcriptional regulation by DEAF1.
Assuntos
Deficiência Intelectual/genética , Transtornos Mentais/genética , Proteínas Nucleares/genética , Distúrbios da Fala/genética , Sequência de Aminoácidos , Animais , Criança , Estudos de Coortes , Análise Mutacional de DNA , Proteínas de Ligação a DNA , Feminino , Humanos , Masculino , Camundongos , Camundongos Knockout , Dados de Sequência Molecular , Mutação , Estrutura Terciária de Proteína/genética , Fatores de TranscriçãoRESUMO
FoxP3+ regulatory CD4 T cells (Tregs) help to maintain the delicate balance between pathogen-specific immunity and immune-mediated pathology. Prior studies suggest that Tregs are induced by P. falciparum both in vivo and in vitro; however, the factors influencing Treg homeostasis during acute and chronic infections, and their role in malaria immunopathogenesis, remain unclear. We assessed the frequency and phenotype of Tregs in well-characterized cohorts of children residing in a region of high malaria endemicity in Uganda. We found that both the frequency and absolute numbers of FoxP3+ Tregs in peripheral blood declined markedly with increasing prior malaria incidence. Longitudinal measurements confirmed that this decline occurred only among highly malaria-exposed children. The decline of Tregs from peripheral blood was accompanied by reduced in vitro induction of Tregs by parasite antigen and decreased expression of TNFR2 on Tregs among children who had intense prior exposure to malaria. While Treg frequencies were not associated with protection from malaria, there was a trend toward reduced risk of symptomatic malaria once infected with P. falciparum among children with lower Treg frequencies. These data demonstrate that chronic malaria exposure results in altered Treg homeostasis, which may impact the development of antimalarial immunity in naturally exposed populations.
Assuntos
Malária Falciparum/imunologia , Malária/imunologia , Plasmodium falciparum/fisiologia , Linfócitos T Reguladores/citologia , Criança , Pré-Escolar , Fatores de Transcrição Forkhead/imunologia , Humanos , Lactente , Malária/parasitologia , Linfócitos T Reguladores/imunologia , Uganda/epidemiologiaRESUMO
γδ T cells expressing Vδ2 may be instrumental in the control of malaria, because they inhibit the replication of blood-stage parasites in vitro and expand during acute malaria infection. However, Vδ2 T-cell frequencies and function are lower among children with heavy prior malaria exposure. It remains unclear whether malaria itself is driving this loss. Here we measure Vδ2 T-cell frequency, cytokine production, and degranulation longitudinally in Ugandan children enrolled in a malaria chemoprevention trial from 6 to 36 months of age. We observed a progressive attenuation of the Vδ2 response only among children incurring high rates of malaria. Unresponsive Vδ2 T cells were marked by expression of CD16, which was elevated in the setting of high malaria transmission. Moreover, chemoprevention during early childhood prevented the development of dysfunctional Vδ2 T cells. These observations provide insight into the role of Vδ2 T cells in the immune response to chronic malaria.
Assuntos
Malária Falciparum/imunologia , Malária Falciparum/prevenção & controle , Plasmodium falciparum/imunologia , Receptores de Antígenos de Linfócitos T gama-delta/imunologia , Receptores de IgG/imunologia , Subpopulações de Linfócitos T/imunologia , Regulação para Cima/imunologia , Artemisininas/administração & dosagem , Pré-Escolar , Combinação de Medicamentos , Proteínas Ligadas por GPI/imunologia , Humanos , Tolerância Imunológica , Lactente , Estudos Longitudinais , Pirimetamina/administração & dosagem , Quinolinas/administração & dosagem , Sulfadoxina/administração & dosagemRESUMO
BACKGROUND: Experimental inoculation of viable Plasmodium falciparum sporozoites administered with chemoprevention targeting blood-stage parasites results in protective immunity. It is unclear whether chemoprevention similarly enhances immunity following natural exposure to malaria. METHODS: We assessed P. falciparum-specific T-cell responses among Ugandan children who were randomly assigned to receive monthly dihydroartemisinin-piperaquine (DP; n = 87) or no chemoprevention (n = 90) from 6 to 24 months of age, with pharmacologic assessments for adherence, and then clinically followed for an additional year. RESULTS: During the intervention, monthly DP reduced malaria episodes by 55% overall (P < .001) and by 97% among children who were highly adherent to DP (P < .001). In the year after the cessation of chemoprevention, children who were highly adherent to DP had a 55% reduction in malaria incidence as compared to children given no chemoprevention (P = .004). Children randomly assigned to receive DP had higher frequencies of blood-stage specific CD4(+) T cells coproducing interleukin-2 and tumor necrosis factor α (P = .003), which were associated with protection from subsequent clinical malaria and parasitemia, and fewer blood-stage specific CD4(+) T cells coproducing interleukin-10 and interferon γ (P = .001), which were associated with increased risk of malaria. CONCLUSIONS: In this setting, effective antimalarial chemoprevention fostered the development of CD4(+) T cells that coproduced interleukin 2 and tumor necrosis factor α and were associated with prospective protection, while limiting CD4(+) T-cell production of the immunoregulatory cytokine IL-10.
Assuntos
Antimaláricos/administração & dosagem , Linfócitos T CD4-Positivos/imunologia , Quimioprevenção/métodos , Interleucina-10/metabolismo , Malária Falciparum/patologia , Malária Falciparum/prevenção & controle , Adolescente , Adulto , Artemisininas/administração & dosagem , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Quinolinas/administração & dosagem , Uganda , Adulto JovemRESUMO
BACKGROUND: In malaria-endemic areas, the first exposure to malaria antigens often occurs in utero when the fetal immune system is poised towards the development of tolerance. Children exposed to placental malaria have an increased risk of clinical malaria in the first few years of life compared to unexposed children. Recent work has suggested the potential of pregnancy-associated malaria to induce immune tolerance in children living in malaria-endemic areas. A study was completed to evaluate the effect of malaria exposure during pregnancy on fetal immune tolerance and effector responses. METHODS: Using cord blood samples from a cohort of mother-infant pairs followed from early in pregnancy until delivery, flow cytometry analysis was completed to assess the relationship between pregnancy-associated malaria and fetal cord blood CD4 and dendritic cell phenotypes. RESULTS: Cord blood FoxP3+ Treg counts were higher in infants born to mothers with Plasmodium parasitaemia early in pregnancy (12-20 weeks of gestation; p = 0.048), but there was no association between Treg counts and the presence of parasites in the placenta at the time of delivery (by loop-mediated isothermal amplification (LAMP); p = 0.810). In contrast, higher frequencies of activated CD4 T cells (CD25+FoxP3-CD127+) were observed in the cord blood of neonates with active placental Plasmodium infection at the time of delivery (p = 0.035). This population exhibited evidence of effector memory differentiation, suggesting priming of effector T cells in utero. Lastly, myeloid dendritic cells were higher in the cord blood of infants with histopathologic evidence of placental malaria (p < 0.0001). CONCLUSION: Together, these data indicate that in utero exposure to malaria drives expansion of both regulatory and effector T cells in the fetus, and that the timing of this exposure has a pivotal role in determining the polarization of the fetal immune response.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Malária/imunologia , Doenças Placentárias/imunologia , Plasmodium/imunologia , Complicações Infecciosas na Gravidez/imunologia , Estudos de Coortes , Células Dendríticas/imunologia , Feminino , Sangue Fetal/imunologia , Citometria de Fluxo , Humanos , Imunofenotipagem , Recém-Nascido , Gravidez , Adulto JovemRESUMO
BACKGROUND: Mechanisms mediating immunity to malaria remain unclear, but animal data and experimental human vaccination models suggest a critical role for CD4(+) T cells. Advances in multiparametric flow cytometry have revealed that the functional quality of pathogen-specific CD4(+) T cells determines immune protection in many infectious models. Little is known about the functional characteristics of Plasmodium-specific CD4(+) T-cell responses in immune and nonimmune individuals. METHODS: We compared T-cell responses to Plasmodium falciparum among household-matched children and adults residing in settings of high or low malaria transmission in Uganda. Peripheral blood mononuclear cells were stimulated with P. falciparum antigen, and interferon γ (IFN-γ), interleukin 2, interleukin 10, and tumor necrosis factor α (TNF-α) production was analyzed via multiparametric flow cytometry. RESULTS: We found that the magnitude of the CD4(+) T-cell responses was greater in areas of high transmission but similar between children and adults in each setting type. In the high-transmission setting, most P. falciparum-specific CD4(+) T-cells in children produced interleukin 10, while responses in adults were dominated by IFN-γ and TNF-α. In contrast, in the low-transmission setting, responses in both children and adults were dominated by IFN-γ and TNF-α. CONCLUSIONS: These findings highlight major differences in the CD4(+) T-cell response of immune adults and nonimmune children that may be relevant for immune protection from malaria.
Assuntos
Linfócitos T CD4-Positivos/imunologia , Malária Falciparum/imunologia , Plasmodium falciparum/imunologia , Adulto , Criança , Pré-Escolar , Doenças Endêmicas , Feminino , Humanos , Interferon gama/sangue , Interleucina-10/sangue , Estudos Longitudinais , Malária Falciparum/epidemiologia , Malária Falciparum/parasitologia , Malária Falciparum/transmissão , Masculino , Pessoa de Meia-Idade , Fenótipo , Uganda/epidemiologiaRESUMO
The use of pesticides to reduce mosquito vector populations is a cornerstone of global malaria control efforts, but the biological impact of most pesticides on human populations, including pregnant women and infants, is not known. Some pesticides, including carbamates, have been shown to perturb the human immune system. We measure the systemic absorption and immunologic effects of bendiocarb, a commonly used carbamate pesticide, following household spraying in a cohort of pregnant Ugandan women and their infants. We find that bendiocarb is present at high levels in maternal, umbilical cord, and infant plasma of individuals exposed during pregnancy, indicating that it is systemically absorbed and trans-placentally transferred to the fetus. Moreover, bendiocarb exposure is associated with numerous changes in fetal immune cell homeostasis and function, including a dose-dependent decrease in regulatory CD4 T cells, increased cytokine production, and inhibition of antigen-driven proliferation. Additionally, prenatal bendiocarb exposure is associated with higher post-vaccination measles titers at one year of age, suggesting that its impact on functional immunity may persist for many months after birth. These data indicate that in utero bendiocarb exposure has multiple previously unrecognized biological effects on the fetal immune system.
Assuntos
Poluentes Ambientais/efeitos adversos , Feto/imunologia , Exposição Materna/efeitos adversos , Sarampo/sangue , Praguicidas/efeitos adversos , Adulto , Anticorpos Antivirais/sangue , Pré-Escolar , Ensaios Clínicos Fase III como Assunto , Feminino , Sangue Fetal/química , Seguimentos , Humanos , Sistema Imunitário/efeitos dos fármacos , Imunogenicidade da Vacina , Imunoglobulina G/sangue , Lactente , Recém-Nascido , Malária/prevenção & controle , Troca Materno-Fetal/imunologia , Sarampo/imunologia , Sarampo/prevenção & controle , Vacina contra Sarampo/administração & dosagem , Vacina contra Sarampo/imunologia , Controle de Mosquitos/métodos , Praguicidas/análise , Fenilcarbamatos/efeitos adversos , Fenilcarbamatos/análise , Gravidez , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
Malaria remains a significant cause of morbidity and mortality worldwide, particularly in infants and children. Some studies have reported that exposure to malaria antigens in utero results in the development of tolerance, which could contribute to poor immunity to malaria in early life. However, the effector T cell response to pathogen-derived antigens encountered in utero, including malaria, has not been well characterized. Here, we assessed the frequency, phenotype, and function of cord blood T cells from Ugandan infants born to mothers with and without placental malaria. We found that infants born to mothers with active placental malaria had elevated frequencies of proliferating effector memory fetal CD4+ T cells and higher frequencies of CD4+ and CD8+ T cells that produced inflammatory cytokines. Fetal CD4+ and CD8+ T cells from placental malaria-exposed infants exhibited greater in vitro proliferation to malaria antigens. Malaria-specific CD4+ T cell proliferation correlated with prospective protection from malaria during childhood. These data demonstrate that placental malaria is associated with the generation of proinflammatory malaria-responsive fetal T cells. These findings add to our current understanding of fetal immunity and indicate that a functional and protective pathogen-specific T cell response can be generated in utero.
Assuntos
Apresentação Cruzada/imunologia , Malária/imunologia , Linfócitos T/imunologia , Antígenos de Protozoários/imunologia , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD8-Positivos/imunologia , Diferenciação Celular , Proliferação de Células , Citocinas/metabolismo , Feminino , Feto/imunologia , Humanos , Memória Imunológica , Lactente , Mediadores da Inflamação/metabolismo , Peptídeos/imunologia , GravidezRESUMO
Sex differences in the immune response and in infectious disease susceptibility have been well described, although the mechanisms underlying these differences remain incompletely understood. We evaluated the frequency of cord blood CD4 T cell subsets in a highly malaria-exposed birth cohort of mother-infant pairs in Uganda by sex. We found that frequencies of cord blood regulatory T cell ([Treg] CD4+CD25+FoxP3+CD127lo/-) differed by infant sex, with significantly lower frequencies of Tregs in female than in male neonates (P = .006). When stratified by in utero malaria exposure status, this difference was observed in the exposed, but not in the unexposed infants.
RESUMO
Cytokine-producing CD4 T cells have important roles in immunity against Plasmodium falciparum (Pf) malaria. However, the factors influencing functional differentiation of Pf-specific CD4 T cells in naturally exposed children are not well understood. Moreover, it is not known which CD4 T-cell cytokine-producing subsets are most critical for protection. We measured Pf-specific IFNγ-, IL10-, and TNFα-producing CD4 T-cell responses by multi-parametric flow cytometry in 265 children aged 6 months to 10 years enrolled in a longitudinal observational cohort in a high malaria transmission site in Uganda. We found that both age and parasite burden were independently associated with cytokine production by CD4 T cells. IL10 production by IFNγ+ CD4 T cells was higher in younger children and in those with high-parasite burden during recent infection. To investigate the role of CD4 T cells in immunity to malaria, we measured associations of Pf-specific CD4 cytokine-producing cells with the prospective risk of Pf infection and clinical malaria, adjusting for household exposure to Pf-infected mosquitos. Overall, the prospective risk of infection was not associated with the total frequency of Pf-specific CD4 T cells, nor of any cytokine-producing CD4 subset. However, the frequency of CD4 cells producing IL10 but not inflammatory cytokines (IFNγ and TNFα) was associated with a decreased risk of clinical malaria once infected. These data suggest that functional polarization of the CD4 T-cell response may modulate the clinical manifestations of malaria and play a role in naturally acquired immunity.
RESUMO
Vδ2+ γδ T cells are semi-innate T cells that expand markedly following P. falciparum (Pf) infection in naïve adults, but are lost and become dysfunctional among children repeatedly exposed to malaria. The role of these cells in mediating clinical immunity (i.e. protection against symptoms) to malaria remains unclear. We measured Vδ2+ T cell absolute counts at acute and convalescent malaria timepoints (n = 43), and Vδ2+ counts, cellular phenotype, and cytokine production following in vitro stimulation at asymptomatic visits (n = 377), among children aged 6 months to 10 years living in Uganda. Increasing age was associated with diminished in vivo expansion following malaria, and lower Vδ2 absolute counts overall, among children living in a high transmission setting. Microscopic parasitemia and expression of the immunoregulatory markers Tim-3 and CD57 were associated with diminished Vδ2+ T cell pro-inflammatory cytokine production. Higher Vδ2 pro-inflammatory cytokine production was associated with protection from subsequent Pf infection, but also with an increased odds of symptoms once infected. Vδ2+ T cells may play a role in preventing malaria infection in children living in endemic settings; progressive loss and dysfunction of these cells may represent a disease tolerance mechanism that contributes to the development of clinical immunity to malaria.
Assuntos
Malária/imunologia , Receptores de Antígenos de Linfócitos T gama-delta/metabolismo , Linfócitos T/imunologia , Linfócitos T/metabolismo , Fatores Etários , Biomarcadores , Criança , Pré-Escolar , Citocinas/biossíntese , Humanos , Contagem de Linfócitos , Malária/diagnóstico , Malária/metabolismo , Malária/parasitologia , Parasitemia/imunologia , Parasitemia/metabolismo , Parasitemia/parasitologia , Plasmodium falciparum/imunologiaRESUMO
In humans, immunity to Plasmodium sp. generally takes the form of protection from symptomatic malaria (i.e., 'clinical immunity') rather than infection ('sterilizing immunity'). In contrast, mice infected with Plasmodium develop sterilizing immunity, hindering progress in understanding the mechanistic basis of clinical immunity. Here we present a novel model in which mice persistently infected with P. chabaudi exhibit limited clinical symptoms despite sustaining patent parasite burdens for many months. Characterization of immune responses in persistently infected mice revealed development of CD4+ T cell exhaustion, increased production of IL-10, and expansion of B cells with an atypical surface phenotype. Additionally, persistently infected mice displayed a dramatic increase in circulating nonclassical monocytes, a phenomenon that we also observed in humans with both chronic Plasmodium exposure and asymptomatic infection. Following pharmacological clearance of infection, previously persistently infected mice could not control a secondary challenge, indicating that persistent infection disrupts the sterilizing immunity that typically develops in mouse models of acute infection. This study establishes an animal model of asymptomatic, persistent Plasmodium infection that recapitulates several central aspects of the immune response in chronically exposed humans. As such, it provides a novel tool for dissection of immune responses that may prevent development of sterilizing immunity and limit pathology during infection.