RESUMO
We describe a role for ECM as a biosensor for inflammatory microenvironments that plays a critical role in peripheral immune tolerance. We show that hyaluronan (HA) promotes induction of Foxp3- IL-10-producing regulatory T cells (TR1) from conventional T-cell precursors in both murine and human systems. This is, to our knowledge, the first description of an ECM component inducing regulatory T cells. Intact HA, characteristic of healing tissues, promotes induction of TR1 capable of abrogating disease in an IL-10-dependent mouse colitis model whereas fragmentary HA, typical of inflamed tissues, does not, indicating a decisive role for tissue integrity in this system. The TR1 precursor cells in this system are CD4(+)CD62L(-)FoxP3(-), suggesting that effector memory cells assume a regulatory phenotype when they encounter their cognate antigen in the context of intact HA. Matrix integrity cues might thereby play a central role in maintaining peripheral tolerance. This TR1 induction is mediated by CD44 cross-linking and signaling through p38 and ERK1/2. This induction is suppressed, also in a CD44-dependent manner, by osteopontin, a component of chronically inflamed ECM, indicating that CD44 signaling serves as a nexus for fate decisions regarding TR1 induction. Finally, we demonstrate that TR1 induction signals can be recapitulated using synthetic matrices. These results reveal important roles for the matrix microenvironment in immune regulation and suggest unique strategies for immunomodulation.
Assuntos
Matriz Extracelular/imunologia , Interleucina-10/biossíntese , Células Precursoras de Linfócitos T/imunologia , Linfócitos T Reguladores/imunologia , Animais , Linfócitos T CD4-Positivos/imunologia , Colite/imunologia , Fatores de Transcrição Forkhead/imunologia , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/imunologia , Humanos , Receptores de Hialuronatos/imunologia , Ácido Hialurônico/imunologia , Memória Imunológica , Técnicas In Vitro , Interleucina-2/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Osteopontina/imunologia , Subpopulações de Linfócitos T/imunologiaRESUMO
Multiple studies of B- and T-cell compartments and their response to stimuli demonstrate alterations in established type 1 diabetes (T1D). Yet it is not known whether these alterations reflect immune mechanisms that initiate islet autoimmunity, promote disease progression, or are secondary to disease. To address these questions, we used samples from the TrialNet Pathway to Prevention study to investigate T-cell responses to interleukin (IL)-2 and regulatory T cell-mediated suppression, the composition of the B-cell compartment, and B-cell responses to B-cell receptor and IL-21 receptor engagement. These studies revealed stage-dependent T- and B-cell functional and immune phenotypes; namely, early features that differentiate autoantibody-positive at-risk first-degree relatives (FDRs) from autoantibody-negative FDRs and persisted through clinical diagnosis; late features that arose at or near T1D diagnosis; and dynamic features that were enhanced early and blunted at later disease stages, indicating evolving responses along the continuum of T1D. We further explored how these specific phenotypes are influenced by therapeutic interventions. Our integrated studies provide unique insights into stable and dynamic stage-specific immune states and define novel immune phenotypes of potential clinical relevance.
Assuntos
Linfócitos B/imunologia , Diabetes Mellitus Tipo 1/imunologia , Linfócitos T Auxiliares-Indutores/imunologia , Adolescente , Adulto , Doenças Assintomáticas , Autoanticorpos/imunologia , Subpopulações de Linfócitos B/imunologia , Linfócitos B/efeitos dos fármacos , Criança , Progressão da Doença , Feminino , Humanos , Memória Imunológica/imunologia , Interleucina-2/farmacologia , Masculino , Fenótipo , Receptores de Antígenos de Linfócitos B/imunologia , Receptores de Interleucina-21/imunologia , Subpopulações de Linfócitos T/imunologia , Linfócitos T Auxiliares-Indutores/efeitos dos fármacos , Linfócitos T Reguladores/imunologia , Adulto JovemRESUMO
Patients with multiple sclerosis (MS) manifest demyelination and neurodegeneration mediated in part by CD4(+) T cells that have escaped regulation. Resistance of pathogenic effector T cells (T(effs)) to suppression by regulatory T cells (T(regs)) has been demonstrated in several autoimmune diseases. Although impairment in T(reg) number and function has been observed in relapsing-remitting MS (RRMS), T(eff) resistance has not been well studied in this disease. To determine whether T(eff) resistance contributes to failed tolerance in RRMS, we performed T(reg) suppression assays with T(effs) from either RRMS patients not on immunomodulatory therapy or healthy individuals. T(eff) resistance was present in the T(effs) of RRMS patients with active disease but not from patients with inactive disease. Interleukin-6 (IL-6) and phosphorylation of signal transducer and activator of transcription 3 (pSTAT3) promote T(eff) resistance to T(regs), and we found an increase in IL-6 receptor α (IL-6Rα) expression and elevated IL-6 signaling as measured by pSTAT3 in our RRMS subjects. Further, the impaired suppression in RRMS subjects correlated with an increase in IL-6Rα surface expression on CD4(+) T cells and an increase in pSTAT3 in response to IL-6. To address whether the enhanced pSTAT3 contributed to T(eff) resistance in active RRMS patients, we blocked STAT3 phosphorylation and found that impaired suppression was reversed. Therefore, enhanced IL-6R signaling through pSTAT3, in some cases through increased IL-6Rα expression, contributed to T(eff) resistance in active RRMS. These markers may aid in determining disease activity and responsiveness to immunomodulatory therapies in RRMS.
Assuntos
Interleucina-6/metabolismo , Esclerose Múltipla Recidivante-Remitente/imunologia , Transdução de Sinais/imunologia , Linfócitos T Reguladores/imunologia , Fatores de Transcrição Forkhead/metabolismo , Humanos , Esclerose Múltipla Recidivante-Remitente/patologia , Fosforilação , Receptores de Interleucina-6/metabolismo , Fator de Transcrição STAT3/metabolismoRESUMO
Rapamycin/interleukin-2 (IL-2) combination treatment of NOD mice effectively treats autoimmune diabetes. We performed a phase 1 clinical trial to test the safety and immunologic effects of rapamycin/IL-2 combination therapy in type 1 diabetic (T1D) patients. Nine T1D subjects were treated with 2-4 mg/day rapamycin orally for 3 months and 4.5 × 10(6) IU IL-2 s.c. three times per week for 1 month. ß-Cell function was monitored by measuring C-peptide. Immunologic changes were monitored using flow cytometry and serum analyses. Regulatory T cells (Tregs) increased within the first month of therapy, yet clinical and metabolic data demonstrated a transient worsening in all subjects. The increase in Tregs was transient, paralleling IL-2 treatment, whereas the response of Tregs to IL-2, as measured by STAT5 phosphorylation, increased and persisted after treatment. No differences were observed in effector T-cell subset frequencies, but an increase in natural killer cells and eosinophils occurred with IL-2 therapy. Rapamycin/IL-2 therapy, as given in this phase 1 study, resulted in transient ß-cell dysfunction despite an increase in Tregs. Such results highlight the difficulties in translating therapies to the clinic and emphasize the importance of broadly interrogating the immune system to evaluate the effects of therapy.