RESUMO
The SARS-CoV-2 spike (S) glycoprotein contains an immunodominant receptor-binding domain (RBD) targeted by most neutralizing antibodies (Abs) in COVID-19 patient plasma. Little is known about neutralizing Abs binding to epitopes outside the RBD and their contribution to protection. Here, we describe 41 human monoclonal Abs (mAbs) derived from memory B cells, which recognize the SARS-CoV-2 S N-terminal domain (NTD) and show that a subset of them neutralize SARS-CoV-2 ultrapotently. We define an antigenic map of the SARS-CoV-2 NTD and identify a supersite (designated site i) recognized by all known NTD-specific neutralizing mAbs. These mAbs inhibit cell-to-cell fusion, activate effector functions, and protect Syrian hamsters from SARS-CoV-2 challenge, albeit selecting escape mutants in some animals. Indeed, several SARS-CoV-2 variants, including the B.1.1.7, B.1.351, and P.1 lineages, harbor frequent mutations within the NTD supersite, suggesting ongoing selective pressure and the importance of NTD-specific neutralizing mAbs for protective immunity and vaccine design.
Assuntos
Antígenos Virais/imunologia , SARS-CoV-2/imunologia , Animais , Anticorpos Monoclonais/química , Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/imunologia , COVID-19/imunologia , COVID-19/virologia , Cricetinae , Mapeamento de Epitopos , Variação Genética , Modelos Moleculares , Mutação/genética , Testes de Neutralização , Domínios Proteicos , RNA Viral/genética , SARS-CoV-2/isolamento & purificação , SARS-CoV-2/ultraestruturaRESUMO
A Correction to this paper has been published: https://doi.org/10.1038/s41590-021-00929-x.
RESUMO
FOXP3 deficiency in mice and in patients with immune dysregulation polyendocrinopathy enteropathy X-linked (IPEX) syndrome results in fatal autoimmunity by altering regulatory T (Treg) cells. CD4+ T cells in patients with IPEX syndrome and Foxp3-deficient mice were analyzed by single-cell cytometry and RNA-sequencing, revealing heterogeneous Treg-like cells, some very similar to normal Treg cells, others more distant. Conventional T cells showed no widespread activation or helper T cell bias, but a monomorphic disease signature affected all CD4+ T cells. This signature proved to be cell extrinsic since it was extinguished in mixed bone marrow chimeric mice and heterozygous mothers of patients with IPEX syndrome. Normal Treg cells exerted dominant suppression, quenching the disease signature and revealing in mutant Treg-like cells a small cluster of genes regulated cell-intrinsically by FOXP3, including key homeostatic regulators. We propose a two-step pathogenesis model: cell-intrinsic downregulation of core FOXP3-dependent genes destabilizes Treg cells, de-repressing systemic mediators that imprint the disease signature on all T cells, furthering Treg cell dysfunction. Accordingly, interleukin-2 treatment improved the Treg-like compartment and survival.
Assuntos
Diabetes Mellitus Tipo 1/congênito , Diarreia/genética , Fatores de Transcrição Forkhead/deficiência , Doenças Genéticas Ligadas ao Cromossomo X/genética , Doenças do Sistema Imunitário/congênito , Linfócitos T Reguladores/imunologia , Adolescente , Animais , Estudos de Casos e Controles , Criança , Pré-Escolar , Estudos de Coortes , Conjuntos de Dados como Assunto , Diabetes Mellitus Tipo 1/sangue , Diabetes Mellitus Tipo 1/genética , Diabetes Mellitus Tipo 1/imunologia , Diarreia/sangue , Diarreia/imunologia , Modelos Animais de Doenças , Citometria de Fluxo , Fatores de Transcrição Forkhead/genética , Doenças Genéticas Ligadas ao Cromossomo X/sangue , Doenças Genéticas Ligadas ao Cromossomo X/imunologia , Humanos , Doenças do Sistema Imunitário/sangue , Doenças do Sistema Imunitário/genética , Doenças do Sistema Imunitário/imunologia , Lactente , Masculino , Camundongos , Camundongos Transgênicos , Mutação , RNA-Seq , Análise de Célula Única , Linfócitos T Reguladores/metabolismo , Adulto JovemRESUMO
Elucidating the mechanisms that sustain asthmatic inflammation is critical for precision therapies. We found that interleukin-6- and STAT3 transcription factor-dependent upregulation of Notch4 receptor on lung tissue regulatory T (Treg) cells is necessary for allergens and particulate matter pollutants to promote airway inflammation. Notch4 subverted Treg cells into the type 2 and type 17 helper (TH2 and TH17) effector T cells by Wnt and Hippo pathway-dependent mechanisms. Wnt activation induced growth and differentiation factor 15 expression in Treg cells, which activated group 2 innate lymphoid cells to provide a feed-forward mechanism for aggravated inflammation. Notch4, Wnt and Hippo were upregulated in circulating Treg cells of individuals with asthma as a function of disease severity, in association with reduced Treg cell-mediated suppression. Our studies thus identify Notch4-mediated immune tolerance subversion as a fundamental mechanism that licenses tissue inflammation in asthma.
Assuntos
Asma/etiologia , Asma/metabolismo , Fator 15 de Diferenciação de Crescimento/metabolismo , Receptor Notch4/metabolismo , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Alérgenos/imunologia , Análise de Variância , Asma/diagnóstico , Biomarcadores , Suscetibilidade a Doenças , Expressão Gênica , Via de Sinalização Hippo , Humanos , Tolerância Imunológica , Imunofenotipagem , Proteínas Serina-Treonina Quinases/metabolismo , Índice de Gravidade de Doença , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Via de Sinalização WntRESUMO
Regulatory T cells (Treg cells) deficient in the transcription factor Foxp3 lack suppressor function and manifest an effector T (Teff) cell-like phenotype. We demonstrate that Foxp3 deficiency dysregulates metabolic checkpoint kinase mammalian target of rapamycin (mTOR) complex 2 (mTORC2) signaling and gives rise to augmented aerobic glycolysis and oxidative phosphorylation. Specific deletion of the mTORC2 adaptor gene Rictor in Foxp3-deficient Treg cells ameliorated disease in a Foxo1 transcription factor-dependent manner. Rictor deficiency re-established a subset of Treg cell genetic circuits and suppressed the Teff cell-like glycolytic and respiratory programs, which contributed to immune dysregulation. Treatment of Treg cells from patients with FOXP3 deficiency with mTOR inhibitors similarly antagonized their Teff cell-like program and restored suppressive function. Thus, regulatory function can be re-established in Foxp3-deficient Treg cells by targeting their metabolic pathways, providing opportunities to restore tolerance in Treg cell disorders.
Assuntos
Reprogramação Celular/imunologia , Fatores de Transcrição Forkhead/genética , Alvo Mecanístico do Complexo 2 de Rapamicina/metabolismo , Proteína Companheira de mTOR Insensível à Rapamicina/genética , Linfócitos T Reguladores/imunologia , Animais , Células Cultivadas , Feminino , Regulação da Expressão Gênica , Glicólise/fisiologia , Humanos , Masculino , Alvo Mecanístico do Complexo 2 de Rapamicina/antagonistas & inibidores , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fosforilação Oxidativa , Transdução de Sinais , Linfócitos T Reguladores/citologiaRESUMO
Regulatory T (Treg) cells expressing the transcription factor Foxp3 are an essential suppressive T cell lineage of dual origin: Foxp3 induction in thymocytes and mature CD4+ T cells gives rise to thymic (tTreg) and peripheral (pTreg) Treg cells, respectively. While tTreg cells suppress autoimmunity, pTreg cells enforce tolerance to food and commensal microbiota. However, the role of Foxp3 in pTreg cells and the mechanisms supporting their differentiation remain poorly understood. Here, we used genetic tracing to identify microbiota-induced pTreg cells and found that many of their distinguishing features were Foxp3 independent. Lineage-committed, microbiota-dependent pTreg-like cells persisted in the colon in the absence of Foxp3. While Foxp3 was critical for the suppression of a Th17 cell program, colitis, and mastocytosis, pTreg cells suppressed colonic effector T cell expansion in a Foxp3-independent manner. Thus, Foxp3 and the tolerogenic signals that precede and promote its expression independently confer distinct facets of pTreg functionality.
Assuntos
Fatores de Transcrição Forkhead , Linfócitos T Reguladores , Fatores de Transcrição Forkhead/metabolismo , Tolerância Imunológica , Células Th17/metabolismo , Timócitos/metabolismoRESUMO
A cardinal feature of COVID-19 is lung inflammation and respiratory failure. In a prospective multi-country cohort of COVID-19 patients, we found that increased Notch4 expression on circulating regulatory T (Treg) cells was associated with disease severity, predicted mortality, and declined upon recovery. Deletion of Notch4 in Treg cells or therapy with anti-Notch4 antibodies in conventional and humanized mice normalized the dysregulated innate immunity and rescued disease morbidity and mortality induced by a synthetic analog of viral RNA or by influenza H1N1 virus. Mechanistically, Notch4 suppressed the induction by interleukin-18 of amphiregulin, a cytokine necessary for tissue repair. Protection by Notch4 inhibition was recapitulated by therapy with Amphiregulin and, reciprocally, abrogated by its antagonism. Amphiregulin declined in COVID-19 subjects as a function of disease severity and Notch4 expression. Thus, Notch4 expression on Treg cells dynamically restrains amphiregulin-dependent tissue repair to promote severe lung inflammation, with therapeutic implications for COVID-19 and related infections.
Assuntos
Interações Hospedeiro-Patógeno , Imunidade Celular , Pneumonia Viral/etiologia , Pneumonia Viral/metabolismo , Receptor Notch4/metabolismo , Transdução de Sinais , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Anfirregulina/farmacologia , Animais , Biomarcadores , Citocinas/metabolismo , Modelos Animais de Doenças , Suscetibilidade a Doenças , Interações Hospedeiro-Patógeno/imunologia , Humanos , Imuno-Histoquímica , Imunomodulação/efeitos dos fármacos , Mediadores da Inflamação/metabolismo , Vírus da Influenza A/fisiologia , Pulmão/imunologia , Pulmão/metabolismo , Pulmão/patologia , Pulmão/virologia , Camundongos , Camundongos Transgênicos , Pneumonia Viral/patologia , Receptor Notch4/antagonistas & inibidores , Receptor Notch4/genética , Índice de Gravidade de DoençaRESUMO
Regulatory T (Treg) cell identity is defined by the lineage-specifying transcription factor (TF) Foxp3. Here we examined mechanisms of Foxp3 function by leveraging naturally occurring genetic variation in wild-derived inbred mice, which enables the identification of DNA sequence motifs driving epigenetic features. Chromatin accessibility, TF binding, and gene expression patterns in resting and activated subsets of Treg cells, conventional CD4 T cells, and cells expressing a Foxp3 reporter null allele revealed that the majority of Foxp3-dependent changes occurred at sites not bound by Foxp3. Chromatin accessibility of these indirect Foxp3 targets depended on the presence of DNA binding motifs for other TFs, including TCF1. Foxp3 expression correlated with decreased TCF1 and reduced accessibility of TCF1-bound chromatin regions. Deleting one copy of the Tcf7 gene recapitulated Foxp3-dependent negative regulation of chromatin accessibility. Thus, Foxp3 defines Treg cell identity in a largely indirect manner by fine-tuning the activity of other major chromatin remodeling TFs such as TCF1.
Assuntos
Fatores de Transcrição Forkhead/metabolismo , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/metabolismo , Animais , Doenças Autoimunes/etiologia , Doenças Autoimunes/metabolismo , Doenças Autoimunes/patologia , Autoimunidade/genética , Sítios de Ligação , Montagem e Desmontagem da Cromatina , Modelos Animais de Doenças , Epigênese Genética , Feminino , Fatores de Transcrição Forkhead/genética , Regulação da Expressão Gênica , Imuno-Histoquímica , Masculino , Camundongos , Motivos de Nucleotídeos , Especificidade de Órgãos/genética , Especificidade de Órgãos/imunologia , Ligação Proteica , Transativadores/metabolismoRESUMO
The mechanisms by which regulatory T (Treg) cells differentially control allergic and autoimmune responses remain unclear. We show that Treg cells in food allergy (FA) had decreased expression of transforming growth factor beta 1 (TGF-ß1) because of interleukin-4 (IL-4)- and signal transducer and activator of transciription-6 (STAT6)-dependent inhibition of Tgfb1 transcription. These changes were modeled by Treg cell-specific Tgfb1 monoallelic inactivation, which induced allergic dysregulation by impairing microbiota-dependent retinoic acid receptor-related orphan receptor gamma t (ROR-γt)+ Treg cell differentiation. This dysregulation was rescued by treatment with Clostridiales species, which upregulated Tgfb1 expression in Treg cells. Biallelic deficiency precipitated fatal autoimmunity with intense autoantibody production and dysregulated T follicular helper and B cell responses. These results identify a privileged role of Treg cell-derived TGF-ß1 in regulating allergy and autoimmunity at distinct checkpoints in a Tgfb1 gene dose- and microbiota-dependent manner.
Assuntos
Autoimunidade/imunologia , Hipersensibilidade/imunologia , Linfócitos T Reguladores/imunologia , Fator de Crescimento Transformador beta1/imunologia , Adolescente , Animais , Autoimunidade/genética , Linfócitos B/imunologia , Diferenciação Celular , Criança , Pré-Escolar , Hipersensibilidade Alimentar/imunologia , Dosagem de Genes , Humanos , Hipersensibilidade/genética , Imunoglobulina G/imunologia , Lactente , Mastócitos/imunologia , Camundongos , Membro 3 do Grupo F da Subfamília 1 de Receptores Nucleares/metabolismo , Células T Auxiliares Foliculares/imunologia , Linfócitos T Reguladores/metabolismo , Transcrição Gênica , Fator de Crescimento Transformador beta1/genética , Adulto JovemRESUMO
The global emergence of many severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants jeopardizes the protective antiviral immunity induced after infection or vaccination. To address the public health threat caused by the increasing SARS-CoV-2 genomic diversity, the National Institute of Allergy and Infectious Diseases within the National Institutes of Health established the SARS-CoV-2 Assessment of Viral Evolution (SAVE) programme. This effort was designed to provide a real-time risk assessment of SARS-CoV-2 variants that could potentially affect the transmission, virulence, and resistance to infection- and vaccine-induced immunity. The SAVE programme is a critical data-generating component of the US Government SARS-CoV-2 Interagency Group to assess implications of SARS-CoV-2 variants on diagnostics, vaccines and therapeutics, and for communicating public health risk. Here we describe the coordinated approach used to identify and curate data about emerging variants, their impact on immunity and effects on vaccine protection using animal models. We report the development of reagents, methodologies, models and notable findings facilitated by this collaborative approach and identify future challenges. This programme is a template for the response to rapidly evolving pathogens with pandemic potential by monitoring viral evolution in the human population to identify variants that could reduce the effectiveness of countermeasures.
Assuntos
COVID-19 , SARS-CoV-2 , Animais , Evolução Biológica , Vacinas contra COVID-19 , Humanos , National Institute of Allergy and Infectious Diseases (U.S.) , Pandemias/prevenção & controle , Variantes Farmacogenômicos , SARS-CoV-2/genética , SARS-CoV-2/patogenicidade , Estados Unidos/epidemiologia , VirulênciaRESUMO
Receptors of the Notch family direct the differentiation of helper T cell subsets, but their influence on regulatory T cell (T(reg) cell) responses is obscure. We found here that lineage-specific deletion of components of the Notch pathway enhanced T(reg) cell-mediated suppression of type 1 helper T cell (T(H)1 cell) responses and protected against their T(H)1 skewing and apoptosis. In contrast, expression in T(reg) cells of a gain-of-function transgene encoding the Notch1 intracellular domain resulted in lymphoproliferation, exacerbated T(H)1 responses and autoimmunity. Cell-intrinsic canonical Notch signaling impaired T(reg) cell fitness and promoted the acquisition by T(reg) cells of a T(H)1 cell-like phenotype, whereas non-canonical Notch signaling dependent on the adaptor Rictor activated the kinase AKT-transcription factor Foxo1 axis and impaired the epigenetic stability of Foxp3. Our findings establish a critical role for Notch signaling in controlling peripheral T(reg) cell function.
Assuntos
Tolerância Periférica , Receptor Notch1/imunologia , Linfócitos T Reguladores/imunologia , Animais , Proteínas de Transporte/genética , Proteínas de Transporte/imunologia , Epigênese Genética , Feminino , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/imunologia , Doença Enxerto-Hospedeiro/imunologia , Doença Enxerto-Hospedeiro/prevenção & controle , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Mutação , Proteína Companheira de mTOR Insensível à Rapamicina , Receptor Notch1/deficiência , Receptor Notch1/genética , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/imunologia , Transdução de Sinais/imunologia , Células Th1/imunologia , TranscriptomaRESUMO
Bacteria are nonsexual organisms but are capable of exchanging DNA at diverse degrees through homologous recombination. Intriguingly, the rates of recombination vary immensely across lineages where some species have been described as purely clonal and others as "quasi-sexual." However, estimating recombination rates has proven a difficult endeavor and estimates often vary substantially across studies. It is unclear whether these variations reflect natural variations across populations or are due to differences in methodologies. Consequently, the impact of recombination on bacterial evolution has not been extensively evaluated and the evolution of recombination rate-as a trait-remains to be accurately described. Here, we developed an approach based on Approximate Bayesian Computation that integrates multiple signals of recombination to estimate recombination rates. We inferred the rate of recombination of 162 bacterial species and one archaeon and tested the robustness of our approach. Our results confirm that recombination rates vary drastically across bacteria; however, we found that recombination rate-as a trait-is conserved in several lineages but evolves rapidly in others. Although some traits are thought to be associated with recombination rate (e.g., GC-content), we found no clear association between genomic or phenotypic traits and recombination rate. Overall, our results provide an overview of recombination rate, its evolution, and its impact on bacterial evolution.
Assuntos
Bactérias , Teorema de Bayes , Evolução Molecular , Recombinação Homóloga , Bactérias/genética , Bactérias/classificação , Modelos Genéticos , Filogenia , Genoma Bacteriano , Recombinação GenéticaRESUMO
Beluga whales play a critical role in the subsistence economies and cultural heritage of Indigenous communities across the Arctic, yet the effects of Indigenous hunting on beluga whales remain unknown. Here, we integrate paleogenomics, genetic simulations, and stable δ13C and δ15N isotope analysis to investigate 700 y of beluga subsistence hunting in the Mackenzie Delta area of northwestern Canada. Genetic identification of the zooarchaeological remains, which is based on radiocarbon dating, span three time periods (1290 to 1440 CE; 1450 to 1650 CE; 1800 to 1870 CE), indicates shifts across time in the sex ratio of the harvested belugas. The equal number of females and males harvested in 1450 to 1650 CE versus more males harvested in the two other time periods may reflect changes in hunting practices or temporal shifts in beluga availability. We find temporal shifts and sex-based differences in δ13C of the harvested belugas across time, suggesting historical adaptability in the foraging ecology of the whales. We uncovered distinct mitochondrial diversity unique to the Mackenzie Delta belugas, but found no changes in nuclear genomic diversity nor any substructuring across time. Our findings indicate the genomic stability and continuity of the Mackenzie Delta beluga population across the 700 y surveyed, indicating the impact of Inuvialuit subsistence harvests on the genetic diversity of contemporary beluga individuals has been negligible.
Assuntos
Beluga , Animais , Beluga/genética , Territórios do Noroeste , Feminino , Masculino , Caça , Isótopos de Nitrogênio/análise , Isótopos de Carbono/análise , DNA Mitocondrial/genética , InuíteRESUMO
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cell entry starts with membrane attachment and ends with spike (S) protein-catalyzed membrane fusion depending on two cleavage steps, namely, one usually by furin in producing cells and the second by TMPRSS2 on target cells. Endosomal cathepsins can carry out both. Using real-time three-dimensional single-virion tracking, we show that fusion and genome penetration require virion exposure to an acidic milieu of pH 6.2 to 6.8, even when furin and TMPRSS2 cleavages have occurred. We detect the sequential steps of S1-fragment dissociation, fusion, and content release from the cell surface in TMPRRS2-overexpressing cells only when exposed to acidic pH. We define a key role of an acidic environment for successful infection, found in endosomal compartments and at the surface of TMPRSS2-expressing cells in the acidic milieu of the nasal cavity.
Assuntos
COVID-19 , Cavidade Nasal , SARS-CoV-2 , Serina Endopeptidases , Internalização do Vírus , COVID-19/virologia , Furina/genética , Furina/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Cavidade Nasal/química , Cavidade Nasal/virologia , SARS-CoV-2/fisiologia , Serina Endopeptidases/metabolismo , Glicoproteína da Espícula de Coronavírus/metabolismoRESUMO
BACKGROUND: HIV-exposed uninfected infants (HEU) appear more vulnerable to infections compared to their HIV-unexposed uninfected (HUU) peers, generally attributed to poor passive immunity acquired from the mother. This may be due to some genetic factors that could alter the immune system. We thus sought to determine the distribution of Killer Cell Immunoglobulin-Like Receptors (KIRs) genes in HEU versus HUU and study their associations with the occurrence of infection-related hospitalization. METHODS: A cohort study was conducted from May 2019 to April 2020 among HEU and HUU infants, including their follow-up at weeks 6, 12, 24, and 48, in reference pediatric centers in Yaoundé-Cameroon. The infant HIV status and infections were determined. A total of 15 KIR genes were investigated using the sequence-specific primer polymerase chain reaction (PCR-SSP) method. The KIR genes that were significantly associated with HIV-1 status (HEU and HUU) were analyzed for an association with infection-related hospitalizations. This was only possible if, and to the extent that, infection-related hospitalizations varied significantly according to status. Multivariate logistic regression analyses were conducted to determine the association between KIR gene content variants and HIV status, while considering a number of potential confounding factors. Furthermore, the risk was quantified using relative risk, odds ratio, and a 95% confidence interval. The Fisher exact test was employed to compare the frequency of occurrences. A p-value of less than 0.05 was considered statistically significant. RESULTS: In this cohort, a total of 66 infants participated, but only 19 acquired infections requiring hospitalizations (14.81%, 04/27 HUU and 38.46%, 15/39 HEU, p = 0.037). At week 48 (39 HEU and 27 HUU), the relative risk (RR) for infection-related hospitalizations was 2.42 (95% CI: 1.028-5.823) for HEU versus HUU with OR 3.59 (1.037-12.448). KIR2DL1 gene was significantly underrepresented in HEU versus HUU (OR = 0.183, 95%CI: 0.053-0.629; p = 0.003), and the absence of KIR2DL1 was significantly associated with infection-related hospitalization (p < 0.001; aOR = 0.063; 95%CI: 0.017-0.229). CONCLUSION: Compared to HUU, the vulnerability of HEU is driven by KIR2DL1, indicating the protective role of this KIR against infection and hospitalizations.
Assuntos
Infecções por HIV , HIV-1 , Hospitalização , Receptores KIR2DL1 , Humanos , Infecções por HIV/genética , Infecções por HIV/imunologia , Infecções por HIV/epidemiologia , Camarões/epidemiologia , Lactente , Hospitalização/estatística & dados numéricos , HIV-1/fisiologia , Masculino , Feminino , Receptores KIR2DL1/genética , Estudos de Coortes , Recém-Nascido , Predisposição Genética para Doença , Biomarcadores , GenótipoRESUMO
OBJECTIVES: Chronic lung disease is a recognized complication in children with HIV. Acute respiratory exacerbations (ARE) are common among this group and cause significant morbidity. Exhaled nitric oxide (eNO) is a known marker of local airway inflammation. We investigated the association between eNO and ARE, biomarkers of systemic inflammation, and the effect of azithromycin on eNO levels. METHODS: Individuals aged 6-19 years with HIV-associated chronic lung disease in Harare, Zimbabwe, were enrolled in a placebo-controlled randomized trial investigating the effect of 48-week azithromycin treatment on lung function and ARE. eNO levels and biomarkers were measured at inclusion and after treatment in a consecutively enrolled subset of participants. Linear regression and generalized linear models were used to study associations between eNO and ARE, biomarkers, and the effect of azithromycin on eNO levels. RESULTS: In total, 172 participants were included in this sub-study, 86 from the placebo group and 86 from the azithromycin group. Participants experiencing at least one ARE during follow-up had significantly higher eNO levels at baseline than participants who did not (geometric mean ratio 1.13, 95% confidence interval [CI] 1.03-1.24, p = 0.015), adjusted for trial arm, age, sex and history of tuberculosis. Matrix metalloproteinase (MMP)-3, -7, and -10 were significantly associated with higher baseline eNO levels. At 48 weeks, azithromycin treatment did not affect eNO levels (geometric mean ratio 0.86, 95% CI 0.72-1.03, p = 0.103). CONCLUSION: Higher baseline eNO levels were a risk factor for ARE. eNO was associated with proinflammatory biomarkers previously found to contribute to the development of chronic lung disease. The potential use of eNO as a marker of inflammation and risk factor for ARE in HIV-associated chronic lung disease needs further investigation.
Assuntos
Infecções por HIV , Pneumopatias , Criança , Humanos , Azitromicina/uso terapêutico , Biomarcadores , Testes Respiratórios , Infecções por HIV/complicações , Infecções por HIV/tratamento farmacológico , Inflamação , Pneumopatias/etiologia , Óxido Nítrico/análise , Zimbábue , Adolescente , Adulto JovemRESUMO
Commensal microbiota promote mucosal tolerance in part by engaging regulatory T (Treg) cells via Toll-like receptors (TLRs). We report that Treg-cell-specific deletion of the TLR adaptor MyD88 resulted in deficiency of intestinal Treg cells, a reciprocal increase in T helper 17 (Th17) cells and heightened interleukin-17 (IL-17)-dependent inflammation in experimental colitis. It also precipitated dysbiosis with overgrowth of segmented filamentous bacteria (SFB) and increased microbial loads in deep tissues. The Th17 cell dysregulation and bacterial dysbiosis were linked to impaired anti-microbial intestinal IgA responses, related to defective MyD88 adaptor- and Stat3 transcription factor-dependent T follicular regulatory and helper cell differentiation in the Peyer's patches. These findings establish an essential role for MyD88-dependent microbial sensing by Treg cells in enforcing mucosal tolerance and maintaining commensalism by promoting intestinal Treg cell formation and anti-commensal IgA responses.
Assuntos
Colite/imunologia , Infecções por Escherichia coli/imunologia , Escherichia coli/imunologia , Intestinos/imunologia , Fator 88 de Diferenciação Mieloide/metabolismo , Linfócitos T Reguladores/imunologia , Células Th17/imunologia , Animais , Anticorpos Antibacterianos/metabolismo , Diferenciação Celular , Células Cultivadas , Tolerância Imunológica , Imunidade nas Mucosas , Imunoglobulina A/metabolismo , Intestinos/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Modelos Animais , Fator 88 de Diferenciação Mieloide/genética , Fator de Transcrição STAT3/metabolismo , Simbiose/imunologia , Receptores Toll-Like/metabolismoRESUMO
Oral immunotherapy has had limited success in establishing tolerance in food allergy, reflecting failure to elicit an effective regulatory T (Treg) cell response. We show that disease-susceptible (Il4ra(F709)) mice with enhanced interleukin-4 receptor (IL-4R) signaling exhibited STAT6-dependent impaired generation and function of mucosal allergen-specific Treg cells. This failure was associated with the acquisition by Treg cells of a T helper 2 (Th2)-cell-like phenotype, also found in peripheral-blood allergen-specific Treg cells of food-allergic children. Selective augmentation of IL-4R signaling in Treg cells induced their reprogramming into Th2-like cells and disease susceptibility, whereas Treg-cell-lineage-specific deletion of Il4 and Il13 was protective. IL-4R signaling impaired the capacity of Treg cells to suppress mast cell activation and expansion, which in turn drove Th2 cell reprogramming of Treg cells. Interruption of Th2 cell reprogramming of Treg cells might thus provide candidate therapeutic strategies in food allergy.