RESUMEN
OBJECTIVE: CD8+ T cells lacking CD28 were originally reported to be a characteristic feature of juvenile idiopathic arthritis (JIA), but the relevance of these unusual cells to this disease remains to be elucidated. Because of recent evidence that loss of CD28 cells is typical of terminally differentiated lymphocytes, the aim of this study was to examine functional subsets of CD8+ T cells in patients with JIA. METHODS: Blood and/or waste synovial fluid samples were collected from children with a definite diagnosis of JIA (n = 98). Deidentified peripheral blood (n = 33) and cord blood (n = 13) samples from healthy donors were also collected. CD8+ and CD4+ T cells were screened for novel receptors, and where indicated, bioassays were performed to determine the functional relevance of the identified receptor. RESULTS: JIA patients had a naive T cell compartment with shortened telomeres, and their entire T cell pool had reduced proliferative capacity. They had an overabundance of CD31+CD28(null) CD8+ T cells, which was a significant feature of oligoarticular JIA (n = 62) as compared to polyarticular JIA (n = 36). CD31+ CD28(null) CD8+ T cells had limited mitotic capacity and expressed high levels of the senescence antigens histone γH2AX and/or p16. Ligation of CD31, which was independent of the T cell receptor (TCR), sufficiently induced tyrosine phosphorylation, vesicle exocytosis, and production of interferon-γ and interleukin-10. CONCLUSION: These data provide the first evidence of cell senescence, as represented by CD31+CD28(null) CD8+ T cells, in the pathophysiology of JIA. Activation of these unusual cells in a TCR-independent manner suggests that they are maladaptive and could be potential targets for immunotherapy.
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Artritis Juvenil/inmunología , Linfocitos T CD8-positivos/inmunología , Senescencia Celular/fisiología , Activación de Linfocitos/inmunología , Receptores de Antígenos de Linfocitos T/inmunología , Adolescente , Artritis Juvenil/patología , Antígenos CD28 , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/patología , Linfocitos T CD8-positivos/patología , Proliferación Celular , Niño , Inhibidor p16 de la Quinasa Dependiente de Ciclina/metabolismo , Femenino , Sangre Fetal/citología , Sangre Fetal/inmunología , Histonas/metabolismo , Humanos , Masculino , Molécula-1 de Adhesión Celular Endotelial de Plaqueta/metabolismo , Líquido Sinovial/citología , Líquido Sinovial/inmunología , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/patología , Telómero/patología , Factores de TiempoRESUMEN
Metabolic reprogramming in pediatric diffuse midline glioma is driven by gene expression changes induced by the hallmark histone mutation H3K27M, which results in aberrantly permissive activation of oncogenic signaling pathways. Previous studies of diffuse midline glioma with altered H3K27 (DMG-H3K27a) have shown that the RAS pathway, specifically through its downstream kinase, extracellular-signal-related kinase 5 (ERK5), is critical for tumor growth. Further downstream effectors of ERK5 and their role in DMG-H3K27a metabolic reprogramming have not been explored. We establish that ERK5 is a critical regulator of cell proliferation and glycolysis in DMG-H3K27a. We demonstrate that ERK5 mediates glycolysis through activation of transcription factor MEF2A, which subsequently modulates expression of glycolytic enzyme PFKFB3. We show that in vitro and mouse models of DMG-H3K27a are sensitive to the loss of PFKFB3. Multi-targeted drug therapy against the ERK5-PFKFB3 axis, such as with small-molecule inhibitors, may represent a promising therapeutic approach in patients with pediatric diffuse midline glioma.
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Glioma , Histonas , Animales , Niño , Humanos , Ratones , Quinasas MAP Reguladas por Señal Extracelular , Glioma/genética , Glucólisis , Histonas/genética , Fosfofructoquinasa-2 , Monoéster Fosfórico Hidrolasas , Transducción de SeñalRESUMEN
Mammalian orthoreovirus (reovirus) infects most mammals and is associated with celiac disease in humans. In mice, reovirus infects the intestine and disseminates systemically to cause serotype-specific patterns of disease in the brain. To identify receptors conferring reovirus serotype-dependent neuropathogenesis, we conducted a genome-wide CRISPRa screen and identified paired immunoglobulin-like receptor B (PirB) as a receptor candidate. Ectopic expression of PirB allowed reovirus binding and infection. PirB extracelluar D3D4 region is required for reovirus attachment and infectivity. Reovirus binds to PirB with nM affinity as determined by single molecule force spectroscopy. Efficient reovirus endocytosis requires PirB signaling motifs. In inoculated mice, PirB is required for maximal replication in the brain and full neuropathogenicity of neurotropic serotype 3 (T3) reovirus. In primary cortical neurons, PirB expression contributes to T3 reovirus infectivity. Thus, PirB is an entry receptor for reovirus and contributes to T3 reovirus replication and pathogenesis in the murine brain.
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Orthoreovirus de los Mamíferos , Receptores Inmunológicos , Receptores Virales , Infecciones por Reoviridae , Animales , Humanos , Ratones , Anticuerpos Antivirales , Orthoreovirus de los Mamíferos/fisiología , Receptores Inmunológicos/metabolismo , Infecciones por Reoviridae/metabolismo , Receptores Virales/metabolismoRESUMEN
Pregnancy-associated plasma protein A (PAPPA) is a metalloproteinase that controls the tissue availability of insulin-like growth factor (IGF). Homozygous deletion of PAPPA in mice leads to lifespan extension. Since immune function is an important determinant of individual fitness, we examined the natural immune ecology of PAPPA(-/-) mice and their wild-type littermates reared under specific pathogen-free condition with aging. Whereas wild-type mice exhibit classic age-dependent thymic atrophy, 18-month-old PAPPA(-/-) mice maintain discrete thymic cortex and medulla densely populated by CD4(+)CD8(+) thymocytes that are capable of differentiating into single-positive CD4 and CD8 T cells. Old PAPPA(-/-) mice have high levels of T cell receptor excision circles, and have bone marrows enriched for subsets of thymus-seeding progenitors. PAPPA(-/-) mice have an overall larger pool of naive T cells, and also exhibit an age-dependent accumulation of CD44(+)CD43(+) memory T cells similar to wild-type mice. However, CD43(+) T cell subsets of old PAPPA(-/-) mice have significantly lower prevalence of 1B11 and S7, glycosylation isoforms known to inhibit T cell activation with normal aging. In bioassays of cell activation, splenic T cells of old PAPPA(-/-) mice have high levels of activation antigens and cytokine production, and also elicit Ig production by autologous B cells at levels equivalent to young wild-type mice. These data suggest an IGF-immune axis of healthy longevity. Controlling the availability of IGF in the thymus by targeted manipulation of PAPPA could be a way to maintain immune homeostasis during postnatal development and aging.
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Envejecimiento/inmunología , Envejecimiento/patología , Longevidad/inmunología , Proteína Plasmática A Asociada al Embarazo/deficiencia , Timo/inmunología , Timo/patología , Animales , Atrofia , Células de la Médula Ósea/citología , Células de la Médula Ósea/inmunología , Diferenciación Celular , Proliferación Celular , Citocinas/inmunología , Inmunoglobulina G/biosíntesis , Memoria Inmunológica , Factor I del Crecimiento Similar a la Insulina/metabolismo , Cinética , Activación de Linfocitos/inmunología , Ratones , Proteína Plasmática A Asociada al Embarazo/inmunología , Receptores de Antígenos de Linfocitos T/inmunología , Células Madre/citología , Células Madre/inmunología , Subgrupos de Linfocitos T/citología , Subgrupos de Linfocitos T/inmunología , Linfocitos T/citología , Linfocitos T/inmunologíaRESUMEN
OBJECTIVES: Very-long-chain acyl-CoA dehydrogenase deficiency (VLCADD) is a disorder of fatty acid oxidation. Symptoms are managed by dietary supplementation with medium-chain fatty acids that bypass the metabolic block. However, patients remain vulnerable to hospitalisations because of rhabdomyolysis, suggesting pathologic processes other than energy deficit. Since rhabdomyolysis is a self-destructive process that can signal inflammatory/immune cascades, we tested the hypothesis that inflammation is a physiologic dimension of VLCADD. METHODS: All subjects (n = 18) underwent informed consent/assent. Plasma cytokine and cytometry analyses were performed. A prospective case analysis was carried out on a patient with recurrent hospitalisation. Health data were extracted from patient medical records. RESULTS: Patients showed systemic upregulation of nine inflammatory mediators during symptomatic and asymptomatic periods. There was also overall abundance of immune cells with high intracellular expression of IFNγ, IL-6, MIP-1ß (CCL4) and TNFα, and the transcription factors p65-NFκB and STAT1 linked to inflammatory pathways. A case analysis of a patient exhibited already elevated plasma cytokine levels during diagnosis in early infancy, evolving into sustained high systemic levels during recurrent rhabdomyolysis-related hospitalisations. There were corresponding activated leukocytes, with higher intracellular stores of inflammatory molecules in monocytes compared to T cells. Exposure of monocytes to long-chain free fatty acids recapitulated the cytokine signature of patients. CONCLUSION: Pervasive plasma cytokine upregulation and pre-activated immune cells indicate chronic inflammatory state in VLCADD. Thus, there is rationale for practical implementation of clinical assessment of inflammation and/or translational testing, or adoption, of anti-inflammatory intervention(s) for personalised disease management.
RESUMEN
T cells are considered autoimmune effectors in juvenile idiopathic arthritis (JIA), but the antigenic cause of arthritis remains elusive. Since T cells comprise a significant proportion of joint-infiltrating cells, we examined whether the environment in the joint could be shaped through the inflammatory activation by T cells that is independent of conventional TCR signaling. We focused on the analysis of synovial fluid (SF) collected from children with oligoarticular and rheumatoid factor-negative polyarticular JIA. Cytokine profiling of SF showed dominance of five molecules including IL-17A. Cytometric analysis of the same SF samples showed enrichment of αßT cells that lacked both CD4 and CD8 co-receptors [herein called double negative (DN) T cells] and also lacked the CD28 costimulatory receptor. However, these synovial αßT cells expressed high levels of CD31, an adhesion molecule that is normally employed by granulocytes when they transit to sites of injury. In receptor crosslinking assays, ligation of CD31 alone on synovial CD28nullCD31+ DN αßT cells effectively and sufficiently induced phosphorylation of signaling substrates and increased intracytoplasmic stores of cytokines including IL-17A. CD31 ligation was also sufficient to induce RORγT expression and trans-activation of the IL-17A promoter. In addition to T cells, SF contained fibrocyte-like cells (FLC) expressing IL-17 receptor A (IL-17RA) and CD38, a known ligand for CD31. Stimulation of FLC with IL-17A led to CD38 upregulation, and to production of cytokines and tissue-destructive molecules. Addition of an oxidoreductase analog to the bioassays suppressed the CD31-driven IL-17A production by T cells. It also suppressed the downstream IL-17A-mediated production of effectors by FLC. The levels of suppression of FLC effector activities by the oxidoreductase analog were comparable to those seen with corticosteroid and/or biologic inhibitors to IL-6 and TNFα. Collectively, our data suggest that activation of a CD31-driven, αßTCR-independent, IL-17A-mediated T cell-FLC inflammatory circuit drives and/or perpetuates synovitis. With the notable finding that the oxidoreductase mimic suppresses the effector activities of synovial CD31+CD28null αßT cells and IL-17RA+CD38+ FLC, this small molecule could be used to probe further the intricacies of this inflammatory circuit. Such bioactivities of this small molecule also provide rationale for new translational avenue(s) to potentially modulate JIA synovitis.
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Artritis Juvenil/inmunología , Receptores de Antígenos de Linfocitos T/inmunología , Sinovitis/inmunología , Linfocitos T/inmunología , Antígenos CD28 , Niño , Estudios de Cohortes , Citocinas/metabolismo , Femenino , Humanos , Interleucina-17/genética , Masculino , Metaloporfirinas/farmacología , Oxidorreductasas/metabolismo , Fosforilación , Molécula-1 de Adhesión Celular Endotelial de Plaqueta , Regiones Promotoras Genéticas , Proteínas Proto-Oncogénicas c-abl/antagonistas & inhibidores , Subgrupos de Linfocitos T/inmunologíaRESUMEN
The fundamental challenge of aging and long-term survivorship is maintenance of functional independence and compression of morbidity despite a life history of disease. Inasmuch as immunity is a determinant of individual health and fitness, unraveling novel mechanisms of immune homeostasis in late life is of paramount interest. Comparative studies of young and old persons have documented age-related atrophy of the thymus, the contraction of diversity of the T cell receptor (TCR) repertoire, and the intrinsic inefficiency of classical TCR signaling in aged T cells. However, the elderly have highly heterogeneous health phenotypes. Studies of defined populations of persons aged 75 and older have led to the recognition of successful aging, a distinct physiologic construct characterized by high physical and cognitive functioning without measurable disability. Significantly, successful agers have a unique T cell repertoire; namely, the dominance of highly oligoclonal αßT cells expressing a diverse array of receptors normally expressed by NK cells. Despite their properties of cell senescence, these unusual NK-like T cells are functionally active effectors that do not require engagement of their clonotypic TCR. Thus, NK-like T cells represent a beneficial remodeling of the immune repertoire with advancing age, consistent with the concept of immune plasticity. Significantly, certain subsets are predictors of physical/cognitive performance among older adults. Further understanding of the roles of these NK-like T cells to host defense, and how they integrate with other physiologic domains of function are new frontiers for investigation in Aging Biology. Such pursuits will require a research paradigm shift from the usual young-versus-old comparison to the analysis of defined elderly populations. These endeavors may also pave way to age-appropriate, group-targeted immune interventions for the growing elderly population.
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Neoplasias Encefálicas/inmunología , Neoplasias Encefálicas/metabolismo , Proteína 1 Similar a Quitinasa-3/inmunología , Proteína 1 Similar a Quitinasa-3/metabolismo , Glioblastoma/inmunología , Glioblastoma/metabolismo , Macrófagos/inmunología , Macrófagos/metabolismo , Animales , Proteínas Sanguíneas/inmunología , Proteínas Sanguíneas/metabolismo , Neoplasias Encefálicas/terapia , Línea Celular Tumoral , Reprogramación Celular/inmunología , Proteína 1 Similar a Quitinasa-3/genética , Femenino , Galectinas/inmunología , Galectinas/metabolismo , Glioblastoma/terapia , Xenoinjertos , Humanos , Tolerancia Inmunológica , Inmunoterapia , Macrófagos/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones SCID , Modelos Moleculares , Transducción de Señal/inmunología , Escape del Tumor , Microambiente Tumoral/inmunologíaRESUMEN
Aging in the immune system is characterized by the contraction of the lymphocyte repertoire, exemplified by long-lived oligoclonal T cells that pervade the peripheral circulation. T-cell receptor (TCR) repertoire contraction likely explains the decline in immunity with chronological age as evidenced by the increased morbidity and mortality to common and new infections, and the low rates of protective responses to vaccination in the elderly. Interestingly, in vitro senescence models and cross sectional ex vivo studies have consistently demonstrated that senescent (or pre-senescent) T cells and T cells of the aged express unusually high densities of receptors that are normally found on natural killer (NK) cells, the killer cell immunoglobulin-like receptors (KIR) being the most diverse NK receptors (NKR). Molecular studies also show that T cells are programmed to express NKRs/KIRs, and T-cell clonal lineages express a variety of NKRs towards the end stages of their replicative lifespan. We propose that NKR/KIR induction in aging T cells is an adaptational diversification of the immune repertoire. We suggest that NKR/KIR expression in oligoclonal senescent and pre-senescent T cells is a compensatory adaptation to maintain immune competence despite the overall contraction in TCR diversity with aging. NKRs comprise a diverse superfamily of receptors. Mounting evidence for NKR/KIR signaling pathways in T cells divergent from those seen in NK cells indicate that senescent NKR(+)T cells are unique immune effectors. We suggest that appreciation of the functional diversity of these unusual NK-like T cells is central to the creative development of new strategies to enhance protective immunity in the aged.
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Envejecimiento/inmunología , Células Asesinas Naturales/inmunología , Receptores de Antígenos de Linfocitos T/inmunología , Linfocitos T/inmunología , Adulto , Anciano de 80 o más Años , Antígenos CD/inmunología , Antígenos CD28/inmunología , Células Clonales/inmunología , Expresión Génica/inmunología , Genotipo , Humanos , Inmunidad Celular/inmunología , Recién Nacido , FenotipoRESUMEN
OBJECTIVE: To determine associations between circulating markers of immune activation, immune cell senescence, and inflammation with HIV-associated abnormalities of pulmonary function. DESIGN: HIV infection is an independent risk factor for abnormal pulmonary function. Immune activation, immune senescence, and chronic inflammation are characteristics of chronic HIV infection that have been associated with other HIV-associated comorbidities and may be related to pulmonary disease in this population. METHODS: Participants from an HIV-infected cohort (nâ=â147) completed pulmonary function testing (PFT). Markers of T-cell activation and senescence were determined by flow cytometry, and plasma levels of interleukin-6, interleukin-8, and C-reactive protein (CRP) were measured, as was telomere length of peripheral blood mononuclear cells (PBMC). Regression models adjusting for clinical risk factors were constructed to examine relationships between biomarkers and PFT outcomes. RESULTS: Activated CD25(+) T cells and activated/senescent CD69(+)/CD57(+)/CD28(null) CD4(+) T cells, interleukin-6, and CRP were associated with PFT abnormalities. Shortening of PBMC telomere length correlated with airflow obstruction and diffusing impairment. Paradoxically, circulating senescent CD57(+)/CD28(null) CD8(+) T cells were associated with better PFT outcomes. CONCLUSION: Circulating T cells expressing markers of activation and inflammatory cytokine levels are independently correlated with PFT abnormalities in HIV-infected persons. Overall telomere shortening was also associated with pulmonary dysfunction. The paradoxical association of senescent CD8(+) T cells and better PFT outcomes could suggest an unrecognized beneficial compensatory function of such cells or a redistribution of these cells from the circulation to local compartments. Further studies are needed to differentiate and characterize functional subsets of local pulmonary and circulating T-cell populations in HIV-associated pulmonary dysfunction.
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Infecciones por VIH/complicaciones , Infecciones por VIH/inmunología , Enfermedades Pulmonares/epidemiología , Activación de Linfocitos , Linfocitos T/inmunología , Adulto , Envejecimiento , Estudios de Cohortes , Estudios Transversales , Citocinas/sangre , Femenino , Humanos , Enfermedades Pulmonares/patología , Masculino , Persona de Mediana Edad , Pruebas de Función RespiratoriaRESUMEN
Studies comparing chronologically "young" versus "old" humans document age-related decline of classical immunological functions. However, older adults aged ≥65 years have very heterogeneous health phenotypes. A significant number of them are functionally independent and are surviving well into their 8(th)-11(th) decade life, observations indicating that aging or old age is not synonymous with immune incompetence. While there are dramatic age-related changes in the immune system, not all of these changes may be considered detrimental. Here, we review evidences for novel immunologic processes that become elaborated with advancing age that complement preserved classical immune functions and promote immune homeostasis later in life. We propose that elaboration such of late life immunologic properties is indicative of beneficial immune remodeling that is an integral component of successful aging, an emerging physiologic construct associated with similar age-related physiologic adaptations underlying maintenance of physical and cognitive function. We suggest that a systems approach integrating immune, physical, and cognitive functions, rather than a strict immunodeficiency-minded approach, will be key towards innovations in clinical interventions to better promote protective immunity and functional independence among the elderly.
RESUMEN
Exceptional aging has been defined as maintenance of physical and cognitive function beyond the median lifespan despite a history of diseases and/or concurrent subclinical conditions. Since immunity is vital to individual fitness, we examined immunologic fingerprint(s) of highly functional elders. Therefore, survivors of the Cardiovascular Health Study in Pittsburgh, Pennsylvania, USA were recruited (nâ=â140; mean ageâ=â86 years) and underwent performance testing. Blood samples were collected and examined blindly for humoral factors and T cell phenotypes. Based on results of physical and cognitive performance testing, elders were classified as "impaired" or "unimpaired", accuracy of group assignment was verified by discriminant function analysis. The two groups showed distinct immune profiles as determined by factor analysis. The dominant immune signature of impaired elders consisted of interferon (IFN)-γ, interleukin (IL)-6, tumor necrosis factor-α, and T cells expressing inhibitory natural killer-related receptors (NKR) CD158a, CD158e, and NKG2A. In contrast, the dominant signature of unimpaired elders consisted of IL-5, IL-12p70, and IL-13 with co-expression of IFN-γ, IL-4, and IL-17, and T cells expressing stimulatory NKRs CD56, CD16, and NKG2D. In logistic regression models, unimpaired phenotype was predicted independently by IL-5 and by CD4(+)CD28(null)CD56(+)CD57(+) T cells. All elders had high antibody titers to common viruses including cytomegalovirus. In cellular bioassays, T cell receptor (TCR)-independent ligation of either CD56 or NKG2D elicited activation of T cells. Collectively, these data demonstrate the importance of immunological parameters in distinguishing between health phenotypes of older adults. NKR(+) T cells and cytokine upregulation indicate a unique physiologic environment in old age. Correlation of particular NKR(+) T cell subsets and IL-5 with unimpaired performance, and NKR-driven TCR-independent activation of T cells suggest novel immunopathway(s) that could be exploited to improve immunity in old age.
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Envejecimiento/sangre , Envejecimiento/inmunología , Trastornos del Conocimiento/fisiopatología , Citocinas/sangre , Células Asesinas Naturales/inmunología , Subgrupos de Linfocitos T/inmunología , Adolescente , Adulto , Anciano de 80 o más Años , Envejecimiento/fisiología , Antígeno CD56/metabolismo , Fenómenos Fisiológicos Cardiovasculares , Trastornos del Conocimiento/sangre , Trastornos del Conocimiento/inmunología , Regulación de la Expresión Génica/inmunología , Humanos , Inmunidad Humoral , Longevidad/inmunología , Longevidad/fisiología , Masculino , Subfamilia K de Receptores Similares a Lectina de Células NK/metabolismo , Fenotipo , Aptitud Física/fisiología , Subgrupos de Linfocitos T/metabolismo , Adulto JovenRESUMEN
Defects in cholesterol synthesis result in a wide variety of symptoms, from neonatal lethality to the relatively mild dysmorphic features and developmental delay found in individuals with Smith-Lemli-Opitz syndrome. We report here the identification of mutations in sterol-C4-methyl oxidaselike gene (SC4MOL) as the cause of an autosomal recessive syndrome in a human patient with psoriasiform dermatitis, arthralgias, congenital cataracts, microcephaly, and developmental delay. This gene encodes a sterol-C4-methyl oxidase (SMO), which catalyzes demethylation of C4-methylsterols in the cholesterol synthesis pathway. C4-Methylsterols are meiosis-activating sterols (MASs). They exist at high concentrations in the testis and ovary and play roles in meiosis activation. In this study, we found that an accumulation of MASs in the patient led to cell overproliferation in both skin and blood. SMO deficiency also substantially altered immunocyte phenotype and in vitro function. MASs serve as ligands for liver X receptors α and ß(LXRα and LXRß), which are important in regulating not only lipid transport in the epidermis, but also innate and adaptive immunity. Deficiency of SMO represents a biochemical defect in the cholesterol synthesis pathway, the clinical spectrum of which remains to be defined.
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Dermatitis/genética , Discapacidades del Desarrollo/genética , Microcefalia/genética , Oxigenasas de Función Mixta/genética , Oxigenasas de Función Mixta/metabolismo , Mutación , Psoriasis/genética , Adolescente , Colesterol/metabolismo , Dermatitis Exfoliativa/diagnóstico , Dermatitis Exfoliativa/genética , Femenino , Humanos , Ligandos , Receptores X del Hígado , Meiosis , Receptores Nucleares Huérfanos/metabolismoRESUMEN
Degeneration of the thymus and severe contraction of the T cell repertoire with aging suggest that immune homeostasis in old age could be mediated by distinct effectors. Therefore, receptors expressed on T cells as they undergo senescence in vitro, as well as those displayed by circulating T cells during normal chronologic aging, were examined. Monitoring of T cells driven to senescence showed de novo induction of CD56, the prototypic receptor of NK cells. Analysis of fresh T cells in peripheral blood showed an age-dependent induction of CD56. These unusual T cells expressed high levels of Bcl2, p16, and p53, and had limited, or completely lost, ability to undergo cell division, properties consistent with senescence. CD56 cross-linking without TCR ligation on CD56(+) T cells resulted in extensive protein phosphorylation, NF-kappaB activation, and Bax down-regulation. CD56 cross-linking was also sufficient to drive production of various humoral factors. These data suggest that the immunologic environment in old age is functionally distinct, rather than being a dysfunctional version of that seen at a young age. CD56(+) T cells are unique effectors capable of mediating TCR-independent immune cascades that could be harnessed to enhance protective immunity in the elderly.
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Envejecimiento/inmunología , Antígeno CD56/metabolismo , Activación de Linfocitos , Receptores de Antígenos de Linfocitos T/metabolismo , Linfocitos T/inmunología , Adulto , Anciano , Anciano de 80 o más Años , Antígeno CD56/análisis , Inhibidor p16 de la Quinasa Dependiente de Ciclina/metabolismo , Femenino , Humanos , Masculino , Persona de Mediana Edad , FN-kappa B/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Proteína p53 Supresora de Tumor/metabolismoRESUMEN
The hyperthermophilic archaeon Pyrococcus furiosus genome encodes three proteasome component proteins: one alpha protein (PF1571) and two beta proteins (beta1-PF1404 and beta2-PF0159), as well as an ATPase (PF0115), referred to as proteasome-activating nucleotidase. Transcriptional analysis of the P. furiosus dynamic heat shock response (shift from 90 to 105 degrees C) showed that the beta1 gene was up-regulated over twofold within 5 minutes, suggesting a specific role during thermal stress. Consistent with transcriptional data, two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that incorporation of the beta1 protein relative to beta2 into the 20S proteasome (core particle [CP]) increased with increasing temperature for both native and recombinant versions. For the recombinant enzyme, the beta2/beta1 ratio varied linearly with temperature from 3.8, when assembled at 80 degrees C, to 0.9 at 105 degrees C. The recombinant alpha+beta1+beta2 CP assembled at 105 degrees C was more thermostable than either the alpha+beta1+beta2 version assembled at 90 degrees C or the alpha+beta2 version assembled at either 90 degrees C or 105 degrees C, based on melting temperature and the biocatalytic inactivation rate at 115 degrees C. The recombinant CP assembled at 105 degrees C was also found to have different catalytic rates and specificity for peptide hydrolysis, compared to the 90 degrees C assembly (measured at 95 degrees C). Combination of the alpha and beta1 proteins neither yielded a large proteasome complex nor demonstrated any significant activity. These results indicate that the beta1 subunit in the P. furiosus 20S proteasome plays a thermostabilizing role and influences biocatalytic properties, suggesting that beta subunit composition is a factor in archaeal proteasome function during thermal stress, when polypeptide turnover is essential to cell survival.
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Complejo de la Endopetidasa Proteasomal/metabolismo , Subunidades de Proteína/metabolismo , Pyrococcus furiosus/metabolismo , Proteínas Arqueales/genética , Proteínas Arqueales/metabolismo , Proteínas Arqueales/fisiología , Rastreo Diferencial de Calorimetría , Genoma Arqueal , Calor , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Complejo de la Endopetidasa Proteasomal/genética , Complejo de la Endopetidasa Proteasomal/fisiología , Subunidades de Proteína/genética , Subunidades de Proteína/fisiología , Pyrococcus furiosus/genética , Temperatura , Transcripción GenéticaRESUMEN
OBJECTIVE: T cells deficient in CD28 expression have been implicated in the pathogenesis of rheumatoid arthritis (RA). Given that CD28-null T cells are functionally heterogeneous, we undertook this study to screen for novel receptors on these cells. METHODS: Seventy-two patients with RA (ages 35-84 years) and 53 healthy persons (32 young controls ages 19-34 years, 21 older controls ages 39-86 years) were recruited. Phenotypes and proliferative capacity of T cells from fresh leukocytes and of long-term cultures were monitored by flow cytometry. Lung biopsy specimens from patients with RA-associated interstitial pneumonitis (IP) were examined by immunohistochemistry. Receptor functionality was assessed by crosslinking bioassays. RESULTS: Chronic stimulation of CD28(+) T cells in vitro yielded progenies that lacked CD28 but that gained CD56. Ex vivo analysis of leukocytes from patients with extraarticular RA showed a higher frequency of CD56(+),CD28-null T cells than in patients with disease confined to the joints or in healthy controls. CD56(+),CD28-null T cells had nil capacity for proliferation, consistent with cellular senescence. CD56(+) T cells had skewed T cell receptor (TCR) alpha/beta-chain usage and restricted TCR third complementarity-determining region spectra. Histologic studies showed that CD56(+) T cells were components of cellular infiltrates in RA-associated IP. CD56 crosslinking on T cells sufficiently induced cytokine production, although CD56/TCR coligation induced higher production levels. CONCLUSION: Chronic activation of T cells induces counterregulation of CD28 and CD56 expression. The loss of CD28 is accompanied by the gain of CD56 that confers TCR-independent and TCR-dependent activation pathways. We propose that accumulation of CD56(+) T cells in RA contributes to maladaptive immune responses and that CD56(+) T cells are potential targets for therapy.
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Envejecimiento/metabolismo , Artritis Reumatoide/metabolismo , Antígeno CD56/metabolismo , Linfocitos T/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Envejecimiento/inmunología , Artritis Reumatoide/complicaciones , Artritis Reumatoide/inmunología , Biopsia , Técnicas de Cultivo de Célula , Femenino , Citometría de Flujo , Humanos , Pulmón/inmunología , Pulmón/metabolismo , Pulmón/patología , Enfermedades Pulmonares Intersticiales/complicaciones , Enfermedades Pulmonares Intersticiales/metabolismo , Enfermedades Pulmonares Intersticiales/patología , Activación de Linfocitos , Masculino , Persona de Mediana Edad , Linfocitos T/inmunologíaRESUMEN
Proteases are found in every cell, where they recognize and break down unneeded or abnormal polypeptides or peptide-based nutrients within or outside the cell. Genome sequence data can be used to compare proteolytic enzyme inventories of different organisms as they relate to physiological needs for protein modification and hydrolysis. In this review, we exploit genome sequence data to compare hyperthermophilic microorganisms from the euryarchaeotal genus Pyrococcus, the crenarchaeote Sulfolobus solfataricus, and the bacterium Thermotoga maritima. An overview of the proteases in these organisms is given based on those proteases that have been characterized and on putative proteases that have been identified from genomic sequences, but have yet to be characterized. The analysis revealed both similarities and differences in the mechanisms utilized for proteolysis by each of these hyperthermophiles and indicated how these mechanisms relate to proteolysis in less thermophilic cells and organisms.