RESUMEN
BACKGROUND: It is well established that PD-1 is expressed by follicular T cells but its function in regulation of human T helper cells has been unclear. We investigated the expression modality and function of PD-1 expressed by human T cells specialized in helping B cells. RESULTS: We found that PD-1-expressing T cells are heterogeneous in PD-1 expression. We identified three different PD-1-expressing memory T cell subsets (i.e. PD-1(low)+, PD-1(medium)++, and PD-1(high)+++ cells). PD-1+++ T cells expressed CXCR5 and CXCR4 and were localized in the rim of germinal centers. PD-1+ or PD-1++ cells expressed CCR7 and were present mainly in the T cell area or other parts of the B cell follicles. Utilizing a novel antigen density-dependent magnetic sorting (ADD-MS) method, we isolated the three T cell subsets for functional characterization. The germinal center-located PD-1+++ T cells were most efficient in helping B cells and in producing IL-21 and CXCL13. Other PD-1-expressing T cells, enriched with Th1 and Th17 cells, were less efficient than PD-1+++ T cells in these capacities. PD-1+++ T cells highly expressed Ki-67 and therefore appear active in cell activation and proliferation in vivo. IL-2 is a cytokine important for proliferation and survival of the PD-1+++ T cells. In contrast, IL-21, while a major effector cytokine produced by the PD-1-expressing T helper cells, had no function in generation, survival, or proliferation of the PD-1-expressing helper T cells at least in vitro. PD-1 triggering has a suppressive effect on the proliferation and B cell-helping function of PD-1+++ germinal center T cells. CONCLUSION: Our results revealed the phenotype and effector function of PD-1-expressing T helper cell subsets and indicate that PD-1 restrains the B cell-helping function of germinal center-localized T cells to prevent excessive antibody response.
Asunto(s)
Tonsila Palatina/patología , Receptor de Muerte Celular Programada 1/metabolismo , Subgrupos de Linfocitos T/metabolismo , Células TH1/metabolismo , Células Th17/metabolismo , Linfocitos B/inmunología , Linfocitos B/metabolismo , Linfocitos B/patología , Citocinas/inmunología , Citocinas/metabolismo , Citometría de Flujo , Regulación de la Expresión Génica/inmunología , Humanos , Inmunidad Celular , Inmunidad Humoral , Separación Inmunomagnética , Inmunofenotipificación , Activación de Linfocitos/genética , Comunicación Paracrina , Receptor de Muerte Celular Programada 1/genética , Receptor de Muerte Celular Programada 1/inmunología , Receptores CXCR4/inmunología , Receptores CXCR4/metabolismo , Receptores CXCR5/inmunología , Receptores CXCR5/metabolismo , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/patología , Células TH1/inmunología , Células TH1/patología , Células Th17/inmunología , Células Th17/patologíaRESUMEN
It is a question of interest whether Th17 cells express trafficking receptors unique to this Th cell lineage and migrate specifically to certain tissue sites. We found several Th17 cell subsets at different developing stages in a human secondary lymphoid organ (tonsils) and adult, but not in neonatal, blood. These Th17 cell subsets include a novel in vivo-stimulated tonsil IL17+ T cell subset detected without any artificial stimulation in vitro. We investigated in depth the trafficking receptor phenotype of the Th17 cell subsets in tonsils and adult blood. The developing Th17 cells in tonsils highly expressed both Th1- (CCR2, CXCR3, CCR5, and CXCR6) and Th2-associated (CCR4) trafficking receptors. Moreover, Th17 cells share major non-lymphoid tissue trafficking receptors, such as CCR4, CCR5, CCR6, CXCR3, and CXCR6, with FOXP3+ T regulatory cells. In addition, many Th17 cells express homeostatic chemokine receptors (CD62L, CCR6, CCR7, CXCR4, and CXCR5) implicated in T cell migration to and within lymphoid tissues. Expression of CCR6 and CCR4 by some Th17 cells is not a feature unique to Th17 cells but shared with FOXP3+ T cells. Interestingly, the IL17+IFN-gamma+ Th17 cells have the features of both IL17-IFN-gamma+ Th1 and IL17+IFN-gamma- Th17 cells in expression of trafficking receptors. Taken together, our results revealed that Th17 cells are highly heterogeneous, in terms of trafficking receptors, and programmed to share major trafficking receptors with other T cell lineages. These findings have important implications in their distribution in the human body in relation to other regulatory T cell subsets.
Asunto(s)
Interleucina-17/metabolismo , Subgrupos de Linfocitos T/inmunología , Linfocitos T Colaboradores-Inductores/inmunología , Linfocitos T Reguladores/inmunología , Células Cultivadas , Sangre Fetal/inmunología , Factores de Transcripción Forkhead/análisis , Humanos , Tonsila Palatina/inmunología , Receptores de Quimiocina/análisis , Receptores de Quimiocina/metabolismoRESUMEN
The field of tissue engineering/regenerative medicine combines the quantitative principles of engineering with the principles of the life sciences toward the goal of reconstituting structurally and functionally normal tissues and organs. There has been relatively little application of tissue engineering efforts toward the organs of speech, voice, and hearing. The present manuscript describes a study that was conducted in which a biologic scaffold derived from porcine (pig) extracellular matrix (ECM) was used to repair the defect following a hemilaryngectomy procedure in dogs. The ECM-augmented repair was compared with a control standard strap muscle (STM) procedure. The animals were sacrificed after 24 weeks at which time anatomic and histologic analyses were conducted. The ECM repair resulted in a macroscopic and microscopic reconstruction of laryngeal tissue that was superior to that observed with the STM procedure. The importance of regenerated tissue having the same structural and functional characteristics of native tissue is emphasized. A discussion of the mechanisms of ECM remodeling is presented along with the implications of such remodeling in the repair of laryngeal structures.
Asunto(s)
Laringe/cirugía , Ingeniería de Tejidos/métodos , Animales , Perros , Femenino , Modelos Animales , Recuperación de la Función , PorcinosRESUMEN
Regulatory T cells (Tregs) can potentially migrate to the B cell areas of secondary lymphoid tissues and suppress T cell-dependent B cell Ig response. T cell-dependent Ig response requires B cell stimulation by Th cells. It has been unknown whether Tregs can directly suppress B cells or whether they must suppress Th cells to suppress B cell response. We report here that Foxp3+ Tregs are found in T-B area borders and within germinal centers of human lymphoid tissues and can directly suppress B cell Ig response. Although Tregs can effectively suppress T cells, they can also directly suppress B cell response without the need to first suppress Th cells. The direct suppression of B cell Ig production by Tregs is accompanied by inhibition of Ig class switch recombination.
Asunto(s)
Linfocitos B/inmunología , Receptores de Interleucina-2/biosíntesis , Linfocitos T Reguladores/inmunología , Linfocitos B/metabolismo , Células Cultivadas , Factores de Transcripción Forkhead/metabolismo , Humanos , Cambio de Clase de Inmunoglobulina/inmunología , Tonsila Palatina/citología , Tonsila Palatina/inmunología , Tonsila Palatina/metabolismo , Receptores de Superficie Celular/metabolismo , Receptores de Interleucina-2/metabolismoRESUMEN
BACKGROUND: The function of CD57+ CD4+ T cells, constituting a major subset of germinal center T (GC-Th) cells in human lymphoid tissues, has been unclear. There have been contradictory reports regarding the B cell helping function of CD57+ GC-Th cells in production of immunoglobulin (Ig). Furthermore, the cytokine and co-stimulation requirement for their helper activity remains largely unknown. To clarify and gain more insight into their function in helping B cells, we systematically investigated the capacity of human tonsil CD57+ GC-Th cells in inducing B cell Ig synthesis. RESULTS: We demonstrated that CD57+ GC-Th cells are highly efficient in helping B cell production of all four subsets of Ig (IgM, IgG, IgA and IgE) compared to other T-helper cells located in germinal centers or interfollicular areas. CD57+ GC-Th cells were particularly more efficient than other T cells in helping GC-B cells but not naive B cells. CD57+ GC-Th cells induced the expression of activation-induced cytosine deaminase (AID) and class switch recombination in developing B cells. IgG1-3 and IgA1 were the major Ig isotypes induced by CD57+ GC-Th cells. CD40L, but not IL-4, IL-10 and IFN-gamma, was critical in CD57+ GC-Th cell-driven B cell production of Ig. However, IL-10, when added exogenously, significantly enhanced the helper activity of CD57+ GC-Th cells, while TGF-beta1 completely and IFN-gamma partially suppressed the CD57+ GC-Th cell-driven Ig production. CONCLUSIONS: CD57+CD4+ T cells in the germinal centers of human lymphoid tissues are the major T helper cell subset for GC-B cells in Ig synthesis. Their helper activity is consistent with their capacity to induce AID and class switch recombination, and can be regulated by CD40L, IL-4, IL-10 and TGF-beta.
Asunto(s)
Subgrupos de Linfocitos B/inmunología , Linfocitos T CD4-Positivos/inmunología , Antígenos CD57/análisis , Centro Germinal/citología , Cambio de Clase de Inmunoglobulina/fisiología , Subgrupos de Linfocitos T/inmunología , Formación de Anticuerpos/efectos de los fármacos , Formación de Anticuerpos/inmunología , Antígenos CD/análisis , Antígenos de Diferenciación de Linfocitos T/análisis , Centro Germinal/inmunología , Humanos , Isotipos de Inmunoglobulinas/biosíntesis , Interferón gamma/farmacología , Interleucina-10/farmacología , Interleucina-4/farmacología , Lectinas Tipo C , Cooperación Linfocítica/efectos de los fármacos , Tonsila Palatina/citologíaRESUMEN
How Tregs migrate to GCs, and whether they regulate the helper activity of the T cells in GCs (GC-Th cells) remains poorly understood. We found a T cell subset in human tonsils that displays potent suppressive activities toward GC-Th cell-dependent B cell responses. These Tregs with the surface phenotype of CD4+CD25+CD69- migrate well to CCL19, a chemokine expressed in the T cell zone, but poorly to CXCL13, a chemokine expressed in the B cell zone. This migration toward the T cell-rich zone rapidly changes to trafficking toward B cell follicles upon T cell activation. This change in chemotactic behavior upon activation of T cells is consistent with their switch in the expression of the 2 chemokine receptors CXCR5 and CCR7. CD4+CD25+CD69- Tregs suppress GC-Th cells and GC-Th cell-induced B cell responses such as Ig production, survival, and expression of activation-induced cytosine deaminase. Our results have identified a subset of Tregs that is physiologically relevant to GC-Th cell-dependent B cell responses and a potential regulation mechanism for the trafficking of these Tregs to GCs.
Asunto(s)
Movimiento Celular/fisiología , Sistema Inmunológico/fisiología , Activación de Linfocitos , Tonsila Palatina/citología , Subgrupos de Linfocitos T , Linfocitos T/inmunología , Antígenos CD/inmunología , Linfocitos B/inmunología , Quimiocinas/metabolismo , Humanos , Tonsila Palatina/inmunología , Receptores de Quimiocina/metabolismo , Linfocitos T/citología , Linfocitos T Colaboradores-Inductores/inmunologíaRESUMEN
Gene expression profiling was used to compare the gene expression patterns of human germinal center (GC) T helper (Th) cells with other CD4+ T-cell subsets (naive, central, and effector memory T cells). GC-Th cells, specifically localized in germinal centers to help B cells, are distantly related to central and effector memory T cells in global gene expression profiles. GC-Th cells displayed substantial differences in mRNA for adhesion molecules, chemoattractant receptors, and cytokines compared with other populations. Distinct expression of transcriptional factors by GC-Th cells is consistent with the hypothesis that they may be different from other T cells in cell lineage. Interestingly, CXCL13, a critical chemokine for B-cell entry to lymphoid follicles, is one of the most highly up-regulated genes in GC-Th cells. GC-Th cells (but not other T cells) produce and secrete large amounts of functional CXCL13 upon T-cell receptor activation, a process that is dependent on costimulation, requires translation and transcription, and is dramatically enhanced by activation in the presence of GC-B cells. This study revealed for the first time the unique gene expression program of GC-Th cells.