RESUMO
BACKGROUND: Gastroesophageal adenocarcinomas (GEAs) are heterogeneous cancers where immune checkpoint inhibitors have robust efficacy in heavily inflamed microsatellite instability (MSI) or Epstein-Barr virus (EBV)-positive subtypes. Immune checkpoint inhibitor responses are markedly lower in diffuse/genome stable (GS) and chromosomal instable (CIN) GEAs. In contrast to EBV and MSI subtypes, the tumor microenvironment of CIN and GS GEAs have not been fully characterized to date, which limits our ability to improve immunotherapeutic strategies. PATIENTS AND METHODS: Here we aimed to identify tumor-immune cell association across GEA subclasses using data from The Cancer Genome Atlas (N = 453 GEAs) and archival GEA resection specimen (N = 71). The Cancer Genome Atlas RNAseq data were used for computational inferences of immune cell subsets, which were correlated to tumor characteristics within and between subtypes. Archival tissues were used for more spatial immune characterization spanning immunohistochemistry and mRNA expression analyses. RESULTS: Our results confirmed substantial heterogeneity in the tumor microenvironment between distinct subtypes. While MSI-high and EBV+ GEAs harbored most intense T cell infiltrates, the GS group showed enrichment of CD4+ T cells, macrophages and B cells and, in â¼50% of cases, evidence for tertiary lymphoid structures. In contrast, CIN cancers possessed CD8+ T cells predominantly at the invasive margin while tumor-associated macrophages showed tumor infiltrating capacity. Relatively T cell-rich 'hot' CIN GEAs were often from Western patients, while immunological 'cold' CIN GEAs showed enrichment of MYC and cell cycle pathways, including amplification of CCNE1. CONCLUSIONS: These results reveal the diversity of immune phenotypes of GEA. Half of GS gastric cancers have tertiary lymphoid structures and are therefore promising candidates for immunotherapy. The majority of CIN GEAs, however, exhibit T cell exclusion and infiltrating macrophages. Associations of immune-poor CIN GEAs with MYC activity and CCNE1 amplification may enable new studies to determine precise mechanisms of immune evasion, ultimately inspiring new therapeutic modalities.
Assuntos
Adenocarcinoma , Neoplasias Gástricas , Adenocarcinoma/genética , Humanos , Imuno-Histoquímica , Instabilidade de Microssatélites , Neoplasias Gástricas/genética , Microambiente Tumoral/genéticaRESUMO
Most influenza virus infections are associated with mild disease. One approach to estimate the occurrence of influenza virus infections in individuals is via repeated measurement of humoral antibody titres. We used baseline and convalescent antibody titres measured by haemagglutination inhibition (HI) and viral neutralization (VN) assays against influenza A(H1N1), A(H3N2) and B viruses to investigate the characteristics of antibody rises following virologically confirmed influenza virus infections in participants in a community-based study. Multivariate models were fitted in a Bayesian framework to characterize the distribution of changes in antibody titres following influenza A virus infections. In 122 participants with PCR-confirmed influenza A virus infection, homologous antibody titres rose by geometric means of 1·2- to 10·2-fold after infection with A(H1N1), A(H3N2) and A(H1N1)pdm09. Significant cross-reactions were observed between A(H1N1)pdm09 and seasonal A(H1N1). Antibody titre rises for some subtypes and assays varied by age, receipt of oseltamivir treatment, and recent receipt of influenza vaccination. In conclusion, we provided a quantitative description of the mean and variation in rises in influenza virus antibody titres following influenza virus infection. The multivariate patterns in boosting of antibody titres following influenza virus infection could be taken into account to improve estimates of cumulative incidence of infection in seroepidemiological studies.
Assuntos
Anticorpos Antivirais/sangue , Vírus da Influenza A Subtipo H1N1/imunologia , Vírus da Influenza A Subtipo H3N2/imunologia , Vírus da Influenza B/imunologia , Influenza Humana/epidemiologia , Vacinação/estatística & dados numéricos , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Anticorpos Antivirais/imunologia , Antivirais/administração & dosagem , Teorema de Bayes , Criança , Pré-Escolar , Feminino , Hong Kong/epidemiologia , Humanos , Incidência , Influenza Humana/virologia , Masculino , Pessoa de Meia-Idade , Prevalência , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fatores Sexuais , Adulto JovemRESUMO
BACKGROUND: Programmed death-1 (PD-1) receptor/PD-1 ligand (PD-L1) pathway negatively regulates T-cell-mediated responses. The prognostic impact of PD-L1 expression needs to be defined in urothelial carcinoma (UC). PATIENTS AND METHODS: Formalin-fixed paraffin-embedded tumor samples from 160 patients with UC were retrieved. PD-L1 expression was evaluated by immunohistochemistry using a mouse monoclonal anti-PD-L1 antibody (405.9A11). PD-L1 positivity on tumor cell membrane was defined as ≥5% of tumor cell membrane staining. The extent of tumor-infiltrating mononuclear cells (TIMCs) as well as PD-L1 expression on TIMCs was scored from 0 to 4. A score of 2, 3, or 4 was considered PD-L1-positive. Clinico-pathological variables were documented. The Cox regression model was used to assess the association of PD-L1 expression with overall survival (OS) in patients who developed metastases. RESULTS: TIMCs were present in 143 of the 160 patient samples. Out of 160 samples, 32 (20%) had positive PD-L1 expression in tumor cell membrane. Out of 143 samples with TIMCs, 58 (40%) had positive PD-L1 expression in TIMCs. Smoking history, prior BCG use and chromosome 9 loss did not correlate with PD-L1 expression in either tumor cell membrane or TIMCs. PD-L1 positivity was not different between non-invasive or invasive UC. In patients who developed metastases (M1) and were treated with systemic therapy (n = 100), PD-L1 positivity on tumor cell membrane was seen in 14% of patients and did not correlate with OS (P = 0.45). Out of 89 M1 patients who had evaluable PD-L1 on TIMCs, PD-L1 expression was seen in 33% of patients and was significantly associated with longer OS on multivariate analysis (P = 0.0007). CONCLUSION: PD-L1 is widely expressed in tumor cell membrane and TIMCs in UC. PD-L1 in tumor cells was not predictive of OS. However, positive PD-L1 expression in TIMCs was significantly associated with longer survival in those patients who developed metastases.
Assuntos
Antígeno B7-H1/metabolismo , Biomarcadores Tumorais/metabolismo , Carcinoma de Células de Transição/mortalidade , Linfócitos do Interstício Tumoral/metabolismo , Neoplasias Urológicas/mortalidade , Animais , Carcinoma de Células de Transição/metabolismo , Carcinoma de Células de Transição/secundário , Seguimentos , Humanos , Técnicas Imunoenzimáticas , Linfócitos do Interstício Tumoral/patologia , Camundongos , Prognóstico , Taxa de Sobrevida , Neoplasias Urológicas/metabolismo , Neoplasias Urológicas/patologiaRESUMO
We examined factors affecting the immunogenicity of trivalent inactivated influenza vaccination (TIV) in children using the antibody titres of children participating in a Hong Kong community-based study. Antibody titres of strains included in the 2009-2010 northern hemisphere TIV [seasonal A(H1N1), seasonal A(H3N2) and B (Victoria lineage)] and those not included in the TIV [2009 pandemic A(H1N1) and B (Yamagata lineage)] were measured by haemagglutination inhibition immediately before and 1 month after vaccination. Multivariate regression models were fitted in a Bayesian framework to characterize the distribution of changes in antibody titres following vaccination. Statistically significant rises in geometric mean antibody titres were observed against all strains, with a wide variety of standard deviations and correlations in rises observed, with the influenza type B antibodies showing more variability than the type A antibodies. The dynamics of antibody titres after vaccination can be used in more complex models of antibody dynamics in populations.
Assuntos
Anticorpos Antivirais/sangue , Vacinas contra Influenza/imunologia , Influenza Humana/prevenção & controle , Adolescente , Criança , Feminino , Testes de Inibição da Hemaglutinação , Hong Kong , Humanos , Vírus da Influenza A Subtipo H1N1/imunologia , Vírus da Influenza A Subtipo H3N2/imunologia , Vírus da Influenza B/imunologia , Vacinas contra Influenza/administração & dosagem , Masculino , Análise Multivariada , Vacinas de Produtos Inativados/administração & dosagem , Vacinas de Produtos Inativados/imunologiaRESUMO
BACKGROUND: Programmed death ligand-1 (PD-L1) expression in nonclear-cell RCC (non-ccRCC) and its association with clinical outcomes are unknown. METHODS: Formalin-fixed paraffin-embedded (FFPE) specimens were obtained from 101 patients with non-ccRCC. PD-L1 expression was evaluated by immunohistochemistry in both tumor cell membrane and tumor-infiltrating mononuclear cells (TIMC). PD-L1 tumor positivity was defined as ≥5% tumor cell membrane staining. For PD-L1 expression in TIMC, a combined score based on the extent of infiltrate and percentage of positive cells was used. Baseline clinico-pathological characteristics and outcome data [time to recurrence (TTR) and overall survival (OS)] were correlated with PD-L1 staining. RESULTS: Among 101 patients, 11 (10.9%) were considered PD-L1+ in tumor cells: 2/36 (5.6%) of chromophobe RCC, 5/50 (10%) of papillary RCC, 3/10 (30%) of Xp11.2 translocation RCC and 1/5 (20%) of collecting duct carcinoma. PD-L1 positivity (PD-L1+) in tumor cells was significantly associated with higher stage (P = 0.01) and grade (P = 0.03), as well as shorter OS (P < 0.001). On the other hand, PD-L1 positivity by TIMC was observed in 57 (56.4%) patients: 13/36 (36.1%) of chromophobe RCC, 30/50 (60%) of papillary RCC, 9/10 (90%) of Xp11.2 translocation RCC and 5/5 (100%) of collecting duct carcinoma. A trend toward shorter OS was observed in patients with PD-L1+ in TIMC (P = 0.08). PD-L1+ in both tumor cell membrane and TIMC cells were associated with shorter TTR (P = 0.02 and P = 0.03, respectively). CONCLUSION: In non-ccRCC, patients with PD-L1+ tumors appear to have worse clinical outcomes, although only PD-L1 positivity in tumor cells is associated with higher tumor stage and grade.
Assuntos
Antígeno B7-H1/biossíntese , Carcinoma de Células Renais/genética , Recidiva Local de Neoplasia/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Antígeno B7-H1/antagonistas & inibidores , Antígeno B7-H1/genética , Carcinoma de Células Renais/tratamento farmacológico , Carcinoma de Células Renais/patologia , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/patologia , Estadiamento de Neoplasias , Análise de Sobrevida , Adulto JovemRESUMO
A growing body of literature suggests that electroconvulsive therapy (ECT) can be safely utilized in patients with craniofacial metallic implants. Here we provide radiographic images and the clinical course of a 49-year-old woman with both maxillary and mandibular metallic implants who safely received ECT.
Assuntos
Eletroconvulsoterapia/métodos , Prótese Maxilofacial/efeitos adversos , Metais , Placas Ósseas/efeitos adversos , Parafusos Ósseos/efeitos adversos , Transtorno Depressivo Maior/terapia , Eletrodos , Feminino , Temperatura Alta , Humanos , Pessoa de Meia-IdadeRESUMO
Picrotoxin is extensively and specifically used to inhibit GABAA receptors and other members of the Cys-loop receptor superfamily. We find that picrotoxin acts independently of known Cys-loop receptors to shorten the period of the circadian clock markedly by specifically advancing the accumulation of PERIOD2 protein. We show that this mechanism is surprisingly tetrodotoxin-insensitive, and the effect is larger than any known chemical or genetic manipulation. Notably, our results indicate that the circadian target of picrotoxin is common to a variety of human and rodent cell types but not Drosophila, thereby ruling out all conserved Cys-loop receptors and known regulators of mammalian PERIOD protein stability. Given that the circadian clock modulates significant aspects of cell physiology including synaptic plasticity, these results have immediate and broad experimental implications. Furthermore, our data point to the existence of an important and novel target within the mammalian circadian timing system.
Assuntos
Relógios Circadianos/efeitos dos fármacos , Receptores de Canais Iônicos de Abertura Ativada por Ligante com Alça de Cisteína/efeitos dos fármacos , Antagonistas GABAérgicos/farmacologia , Proteínas Circadianas Period/metabolismo , Picrotoxina/farmacologia , Animais , Linhagem Celular , Relógios Circadianos/fisiologia , Receptores de Canais Iônicos de Abertura Ativada por Ligante com Alça de Cisteína/fisiologia , Drosophila , Humanos , Técnicas In Vitro , Camundongos , Núcleo Supraquiasmático/efeitos dos fármacos , Núcleo Supraquiasmático/fisiologiaRESUMO
Prevention and treatment of common noncommunicable chronic diseases have been revolutionized by the development of therapies. Recently, several randomized controlled trials (RCTs) designed to assess the efficacy of new therapies targeted at well-established risk factors for noncommunicable chronic diseases have reported lower benefits than expected. Subsequent observational analysis of the same trial data has not clarified these unexpected findings. Mendelian randomization (MR) provides an approach for estimating causal effects from observational or trial data and thus provides information complementary to that from an RCT. An RCT assesses the efficacy of a therapy but does not usually confirm the underlying mechanistic pathway. In contrast, an MR study does not assess the efficacy of a therapy but rather assesses causal effects on an underlying mechanistic pathway. We suggest that incorporating an MR study into an RCT at the design stage would improve etiologic understanding of current therapies and enhance the search for therapies for the significant amount of noncommunicable chronic diseases that resists current treatments.
Assuntos
Doença Crônica/tratamento farmacológico , Humanos , Análise da Randomização Mendeliana , Resultado do TratamentoRESUMO
BACKGROUND: Tumour biopsy for pharmacodynamic (PD) study is increasingly common in early-phase cancer trials. As they are non-diagnostic, the ethical justification for such procedures rests on their knowledge value. On the premise that knowledge value is related to reporting practices and outcome diversity, we assessed in a sample of recent invasive PD studies within cancer trials. METHODS: We assessed reporting practices and outcomes for PD studies in a convenience sample of cancer trials published from 2000 to 2010 that employed invasive, non-diagnostic tissue procurement. Extracted data were used to measure outcome reporting in individual trials. Using a reporting scale we developed for exploratory purposes, we tested whether reporting varied with study characteristics, such as funding source or drug novelty. RESULTS: Reporting varied widely within and across studies. Some practices were sporadically reported, including results of all planned tests (78% trials reporting), use of blinded histopathological assessment (43% trials reporting), biopsy dimensions (38% trials reporting), and description of patient flow through PD analysis (62%). Pharmacodynamic analysis as a primary end point and mandatory biopsy had statistically significant positive relationships with overall quality of reporting. A preponderance of positive results (61% of the studies described positive PD results) suggests possible publication bias. CONCLUSION: Our results highlight the need for PD-reporting guidelines, and suggest several avenues for improving the risk/benefit for studies involving invasive, non-diagnostic tissue procurement.
Assuntos
Biópsia/estatística & dados numéricos , Ensaios Clínicos como Assunto/estatística & dados numéricos , Neoplasias/patologia , Farmacocinética , Projetos de Pesquisa/estatística & dados numéricos , Biomarcadores Tumorais , Biópsia/ética , Ensaios Clínicos como Assunto/ética , Ensaios Clínicos Fase I como Assunto/ética , Ensaios Clínicos Fase I como Assunto/estatística & dados numéricos , Ensaios Clínicos Fase II como Assunto/ética , Ensaios Clínicos Fase II como Assunto/estatística & dados numéricos , HumanosRESUMO
The master coordinator of daily schedules in mammals, located in the ventral hypothalamus, is the suprachiasmatic nucleus (SCN). This relatively small population of neurons and glia generates circadian rhythms in physiology and behavior and synchronizes them to local time. Recent advances have begun to define the roles of specific cells and signals (e.g., peptides, amino acids, and purine derivatives) within this network that generate and synchronize daily rhythms. Here we focus on the best-studied signals between neurons and between glia in the mammalian circadian system with an emphasis on time-of-day pharmacology. Where possible, we highlight how commonly used drugs affect the circadian system.
Assuntos
Relógios Circadianos/fisiologia , Ritmo Circadiano/fisiologia , Neuroglia/fisiologia , Neurônios/fisiologia , Núcleo Supraquiasmático/fisiologia , Animais , Arginina Vasopressina/fisiologia , Humanos , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Peptídeo Intestinal Vasoativo/fisiologia , Ácido gama-Aminobutírico/fisiologiaRESUMO
Between 31 March and 21 April 2013, 102 laboratory-confirmed influenza A(H7N9) infections have been reported in six provinces of China. Using survey data on age-specific rates of exposure to live poultry in China, we estimated that risk of serious illness after infection is 5.1 times higher in persons 65 years and older versus younger ages. Our results suggest that many unidentified mild influenza A(H7N9) infections may have occurred, with a lower bound of 210550 infections to date.
Assuntos
Vírus da Influenza A Subtipo H9N2 , Influenza Aviária/transmissão , Influenza Humana/epidemiologia , Adolescente , Adulto , Fatores Etários , Idoso , Animais , Teorema de Bayes , Aves , Criança , Pré-Escolar , China/epidemiologia , Análise por Conglomerados , Humanos , Lactente , Recém-Nascido , Influenza Humana/transmissão , Pessoa de Meia-Idade , Medição de Risco , Fatores de Risco , População Rural , Índice de Gravidade de Doença , População Urbana , Adulto JovemRESUMO
Liver X receptors (LXRs) are implicated in the regulation of cholesterol homeostasis, inflammatory response and atherogenesis. Administration of LXR agonists inhibits the progress of atherosclerosis, and also increases plasma triglyceride levels, representing an obstacle to their use in treating this disease. The objective of this study was to develop an alternative approach that could overcome this obstacle. Eight-week-old low-density lipoprotein receptor-deficient (LDLR(-/-)) mice were transplanted with hematopoietic stem cell (HSC)-enriched bone marrow cells transduced with lentivectors expressing either green fluorescent protein (GFP) (Lenti-SP-GFP, control) or LXRα (Lenti-SP-LXRα) driven by a synthetic macrophage promoter. At 4 weeks post-transplant, the mice were fed with a Western diet for 8 weeks and then killed. Compared with Lenti-SP-GFP mice, the Lenti-SP-LXRα mice had a 30% reduction in atherosclerotic lesions, which was accompanied by increases in levels of macrophage expression of cholesterol efflux genes apolipoprotein E and ATP-binding cassette A1, as well as decreases in plasma inflammatory cytokines interleukin-6 and tumor necrosis factor-α. Intriguingly, a 50% reduction of plasma triglyceride level was also observed. We conclude that HSC-based macrophage LXRα gene therapy ameliorates the development of atherosclerosis along with an unexpected concomitant reduction of plasma triglyceride levels in LDLR(-/-) mice. These findings highlight the potential value of macrophage LXR expression as an avenue for therapeutic intervention against atherosclerosis.
Assuntos
Aterosclerose/terapia , Terapia Genética/métodos , Hipertrigliceridemia/terapia , Macrófagos/metabolismo , Receptores Nucleares Órfãos/genética , Receptores de LDL/deficiência , Transportador 1 de Cassete de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/genética , Animais , Apolipoproteínas E/genética , Transplante de Medula Óssea/métodos , Feminino , Interleucina-6/sangue , Lentivirus , Receptores X do Fígado , Camundongos , Transdução Genética , Triglicerídeos/sangue , Fator de Necrose Tumoral alfa/sangueRESUMO
Although recent in vitro studies have begun to decipher the molecular events that characterize the anergic state, their in vivo biologic relevance and potential clinical importance remain unclear. Here, using anergic human T-cell clones and tolerant alloreactive mouse T cells that do not induce graft-versus-host disease, we show that p27kip1 cyclin-dependent kinase inhibitor is an essential regulator responsible for the blockade of clonal expansion of anergic T cells in vitro and in vivo. Moreover, in anergic cells, p27kip1 associates with the c-Jun co-activator JAB1, resulting in defective transactivation of AP-1 and interleukin 2 transcription. Therefore, pharmacological agents that upregulate the expression of or prevent the degradation of p27kip1 during antigen recognition should be part of new therapeutic strategies to induce antigen-specific T-cell unresponsiveness.
Assuntos
Proteínas de Ciclo Celular , Anergia Clonal , Regulação da Expressão Gênica/imunologia , Interleucina-2/genética , Proteínas Associadas aos Microtúbulos/fisiologia , Proteínas Proto-Oncogênicas , Linfócitos T Auxiliares-Indutores/citologia , Linfócitos T Auxiliares-Indutores/imunologia , Transcrição Gênica , Proteínas Supressoras de Tumor , Animais , Células COS , Ciclo Celular , Células Clonais , Ciclina D2 , Quinase 4 Dependente de Ciclina , Inibidor de Quinase Dependente de Ciclina p27 , Quinases Ciclina-Dependentes/antagonistas & inibidores , Quinases Ciclina-Dependentes/metabolismo , Ciclinas/metabolismo , Fase G1 , Humanos , Camundongos , TransfecçãoRESUMO
Given the plethora of well-documented breast carcinoma-associated antigens in humans including MAGE-1, -2 and -3, mutated p53, p21ras, HER-2/neu and DF3/MUC-1, coupled with evidence that humoral and cytotoxic T-cell responses against these antigens exist, the central dilemma facing tumor immunologists is why the host immune response is so inefficient. One possibility is that tumor cells themselves are either inefficient or ineffective antigen-presenting cells (APCs). The failure of tumor cells to function as APCs may be due to their inability to process and present the antigen, the absence or insufficient numbers of adhesion and costimulatory molecules or, potentially, the secretion of inhibitory cytokines. Therefore, we sought to determine whether human breast cancer cell lines could function as APCs and, if not, to identify mechanism(s) responsible for this defect. Here, we show that human breast cancer cell lines fail to present alloantigen. This defect does not reside in their inherent capacity to present antigen but rather is due to apoptosis of activated T cells induced by exposure to the breast carcinoma-associated mucin antigen, DF3/MUC1. These results support the hypothesis that DF3/MUC1 may contribute to the paucity of clinically significant anticarcinoma-specific immune responses.
Assuntos
Antígenos de Neoplasias/imunologia , Antígenos Glicosídicos Associados a Tumores , Apoptose/imunologia , Neoplasias da Mama/imunologia , Carcinoma/imunologia , Linfócitos T/imunologia , Células 3T3 , Animais , Células Apresentadoras de Antígenos/imunologia , Antígenos de Neoplasias/farmacologia , Antígeno B7-1/imunologia , Biomarcadores Tumorais , Feminino , Fibroblastos , Antígeno HLA-DR7/imunologia , Humanos , Ativação Linfocitária/efeitos dos fármacos , Teste de Cultura Mista de Linfócitos , Melanoma Experimental , Camundongos , Camundongos Endogâmicos C57BL , Mitógenos/farmacologia , Fito-Hemaglutininas/farmacologia , Células Tumorais CultivadasRESUMO
In this paper, a new neural-fuzzy approach is proposed for automated region segmentation in transrectal ultrasound images of the prostate. The goal of region segmentation is to identify suspicious regions in the prostate in order to provide decision support for the diagnosis of prostate cancer. The new automated region segmentation system uses expert knowledge as well as both textural and spatial features in the image to accomplish the segmentation. The textural information is extracted by two recurrent random pulsed neural networks trained by two sets of data (a suspicious tissues' data set and a normal tissues' data set). Spatial information is captured by the atlas-based reference approach and is represented as fuzzy membership functions. The textural and spatial features are synthesized by a fuzzy inference system, which provides a binary classification of the region to be evaluated.
Assuntos
Lógica Fuzzy , Processamento de Imagem Assistida por Computador/métodos , Reconhecimento Automatizado de Padrão/métodos , Neoplasias da Próstata/diagnóstico por imagem , Algoritmos , Humanos , Masculino , Próstata/diagnóstico por imagem , Curva ROC , Sensibilidade e Especificidade , UltrassonografiaRESUMO
Major histocompatibility complex class II-positive human T cell clones are nontraditional antigen-presenting cells (APCs) that are able to simultaneously present and respond to peptide or degraded antigen, but are unable to process intact protein. Although T cell presentation of peptide antigen resulted in a primary proliferative response, T cells that had been previously stimulated by T cells presenting antigen were completely unresponsive to antigen but not to interleukin 2 (IL-2). In contrast, peptide antigen presented by B cells or DR2+ L cell transfectants resulted in T cell activation and responsiveness to restimulation. The anergy induced by T cell presentation of peptide could not be prevented by the addition of either autologous or allogeneic B cells or B7+ DR2+ L cell transfectants, suggesting that the induction of anergy could occur in the presence of costimulation. T cell anergy was induced within 24 h of T cell presentation of antigen and was long lasting. Anergized T cells expressed normal levels of T cell receptor/CD3 but were defective in their ability to release [Ca2+]i to both alpha CD3 and APCs. Moreover, anergized T cells did not proliferate to alpha CD2 monoclonal antibodies or alpha CD3 plus phorbol myristate acetate (PMA), nor did they synthesize IL-2, IL-4, or interferon gamma mRNA in response to either peptide or peptide plus PMA. In contrast, ionomycin plus PMA induced both normal proliferative responses and synthesis of cytokine mRNA, suggesting that the signaling defect in anergized cells occurs before protein kinase C activation and [Ca2+]i release.
Assuntos
Autoantígenos/imunologia , Tolerância Imunológica , Linfócitos T/imunologia , Células Apresentadoras de Antígenos/fisiologia , Antígenos de Diferenciação de Linfócitos T/análise , Complexo CD3 , Cálcio/metabolismo , Citocinas/biossíntese , Antígenos HLA-DR/imunologia , Humanos , Receptores de Antígenos de Linfócitos T/análise , Acetato de Tetradecanoilforbol/farmacologiaRESUMO
Presentation of antigen by the major histocompatibility complex to T lymphocytes without the requisite costimulatory signals does not induce an immune response but rather results in a state of antigen-specific unresponsiveness, termed anergy. To determine which costimulatory signals are critical for the T cell commitment to activation or anergy, we developed an in vitro model system that isolated the contributions of alloantigen and each candidate costimulatory molecule. Here, we show that transfectants expressing HLA-DR7 and either B7 or intercellular adhesion molecule 1 (ICAM-1) deliver independent costimulatory signals resulting in alloantigen-induced proliferation of CD4-positive T lymphocytes. Although equivalent in their ability to costimulate maximal proliferation of alloreactive T cells, B7 but not ICAM-1 induced detectable interleukin 2 secretion and prevented the induction of alloantigen-specific anergy. These results are consistent with the hypothesis that blockade of the ICAM-1:lymphocyte function-associated 1 pathway results in immunosuppression, whereas blockade of the B7:CD28/CTLA4 pathway results in alloantigen-specific anergy. This approach, using this model system, should facilitate the identification of critical costimulatory pathways which must be inhibited in order to induce alloantigen-specific tolerance before human organ transplantation.
Assuntos
Moléculas de Adesão Celular/metabolismo , Antígeno HLA-B7/metabolismo , Antígeno HLA-DR7/metabolismo , Tolerância Imunológica/efeitos dos fármacos , Isoantígenos/imunologia , Linfócitos T/imunologia , Células 3T3 , Animais , Células Apresentadoras de Antígenos/imunologia , Moléculas de Adesão Celular/biossíntese , Células Cultivadas , Eletroporação , Antígeno HLA-B7/biossíntese , Antígeno HLA-DR7/biossíntese , Humanos , Molécula 1 de Adesão Intercelular , Interleucina-2/biossíntese , Teste de Cultura Mista de Linfócitos , Complexo Principal de Histocompatibilidade , Camundongos , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/metabolismo , Linfócitos T/efeitos dos fármacos , Acetato de Tetradecanoilforbol/farmacologia , TransfecçãoRESUMO
The costimulatory molecule B7.1 provides a second signal critical for T cell activation. The distribution of this integral membrane protein is restricted to certain tissues where its level of expression is modulated by multiple exogenous stimuli. To identify the molecular basis for specificity and inducibility, the chromatin configuration of the human B7.1 gene was examined in intact nuclei from various cell types. The identification of a tissue-specific deoxyribonuclease I hypersensitive site approximately 3kb upstream of the transcription start site led to the characterization of a cell type-specific enhancer region. This 183-bp region was both cell type specific and responsive to two distinct stimuli, lipopolysaccharide and dibutyryl cAMP, known to regulate B7.1 expression. Deletional and site-directed mutagenesis revealed the presence of multiple functionally critical cis elements within this region, one of which was a nuclear factor (NF)-kappaB consensus sequence. In B7.1-positive B cells, this element bound several members of the NF-kappaB family, transcription factors already implicated in signal transduction pathways relevant to B7.1 expression. This is the first description, to our knowledge, of regulatory elements that control expression of a gene encoding a B7 costimulatory molecule.
Assuntos
Antígeno B7-1/biossíntese , Antígeno B7-1/genética , Elementos Facilitadores Genéticos , Regulação da Expressão Gênica , NF-kappa B/metabolismo , Antígenos CD/biossíntese , Antígenos CD/genética , Linfócitos B , Sequência de Bases , Sítios de Ligação , Linhagem Celular , Linhagem Celular Transformada , Núcleo Celular/metabolismo , Clonagem Molecular , Sequência Consenso , Citometria de Fluxo , Humanos , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Oligodesoxirribonucleotídeos , Regiões Promotoras Genéticas , Proteínas Recombinantes/biossíntese , Mapeamento por Restrição , Linfócitos T , Transfecção , Células Tumorais CultivadasRESUMO
Exposure to maternal idiotypes (Ids) or antigens might predispose a child to develop an immunoregulated, asymptomatic clinical presentation of schistosomiasis. We have used an experimental murine system to address the role of Ids in this immunoregulation. Sera from mice with 8-wk Schistosoma mansoni infection, chronic (20-wk infection) moderate splenomegaly syndrome (MSS), or chronic hypersplenomegaly syndrome (HSS) were passed over an S. mansoni soluble egg antigen (SEA) immunoaffinity column to prepare Ids (8WkId, MSS Id, HSS Id). Newborn mice were injected with 8WkId, MSS Id, HSS Id, or normal mouse immunoglobulin (NoMoIgG) and infected with S. mansoni 8 wk later. Mice exposed to 8WkId or MSS Id as newborns had prolonged survival and decreased morbidity compared with mice that received HSS Id or NoMoIgG. When stimulated with SEA, 8WkId, or MSS Id, spleen cells from mice neonatally injected with 8WkId or MSS Id produced more interferon gamma than spleen cells from mice neonatally injected with HSS Id or NoMoIgG. Furthermore, neonatal exposure to 8WkId or MSS Id, but not NoMoIgG or HSS Id, led to significantly smaller granuloma size and lower hepatic fibrosis levels in infected mice. Together, these results indicate that perinatal exposure to appropriate anti-SEA Ids induces long-term effects on survival, pathology, and immune response patterns in mice subsequently infected with S. mansoni.
Assuntos
Animais Recém-Nascidos/imunologia , Anticorpos Anti-Helmínticos/administração & dosagem , Antígenos de Helmintos/imunologia , Imunidade Materno-Adquirida , Imunização Passiva , Idiótipos de Imunoglobulinas/administração & dosagem , Schistosoma mansoni/imunologia , Esquistossomose mansoni/imunologia , Animais , Anticorpos Anti-Helmínticos/imunologia , Modelos Animais de Doenças , Progressão da Doença , Fibrose , Granuloma/etiologia , Granuloma/patologia , Idiótipos de Imunoglobulinas/imunologia , Interferon gama/biossíntese , Fígado/parasitologia , Fígado/patologia , Masculino , Camundongos , Camundongos Endogâmicos CBA , Tamanho do Órgão , Esquistossomose mansoni/patologia , Baço/patologia , Esplenomegalia/etiologia , Esplenomegalia/patologiaRESUMO
For T cells to become functionally activated they require at least two signals. The B7 costimulatory molecules B7-1 and B7-2 provide the "second signal" pivotal for T cell activation. In this report, we studied the relative roles of B7-1 and B7-2 molecules in the induction of antitumor immunity to the T cell thymoma, EL4. We generated EL4 tumor cells that expressed B7-1, B7-2, and B7-1+B7-2 by transfecting murine cDNAs. Our results demonstrate that EL4-B7-1 cells are completely rejected in syngeneic mice. Unlike EL4-B7-1 cells, we find that EL4-B7-2 cells are not rejected but progressively grow in the mice. A B7-1- and B7-2-EL4 double transfectant was generated by introducing B7-2 cDNA into the EL4-B7-1 tumor line that regressed in vivo. The EL4-B7-1+B7-2 double transfectant was not rejected when implanted into syngeneic mice but progressively grew to produce tumors. The double transfectant EL4 cells could costimulate T cell proliferation that could be blocked by anti-B7-1 antibodies, anti-B7-2 antibodies, or hCTLA4 immunoglobulin, showing that the B7-1 and B7-2 molecules expressed on the EL4 cells were functional. In vivo, treatment of mice implanted with double-transfected EL4 cells with anti-B7-2 monoclonal antibody resulted in tumor rejection. Furthermore, the EL4-B7-2 and EL4-B7-1+B7-2 cells, but not the wild-type EL4 cells, were rejected in interleukin 4 (IL-4) knockout mice. Our data suggests that B7-2 expressed on some T cell tumors inhibits development of antitumor immunity, and IL-4 appears to play a critical role in abrogation of the antitumor immune response.