技术资料

T-cell-mediated processes play an essential role in the pathogenesis of several inflammatory skin diseases such as atopic dermatitis,allergic contact dermatitis and psoriasis. The aim of this study was to investigate the role of the IL-2-inducible tyrosine kinase (Itk),an enzyme acting downstream of the T-cell receptor (TCR),in T-cell-dependent skin inflammation using three approaches. Itk knockout mice display significantly reduced inflammatory symptoms in mouse models of acute and subacute contact hypersensitivity (CHS) reactions. Systemic administration of a novel small molecule Itk inhibitor,Compound 44,created by chemical optimization of an initial high-throughput screening hit,inhibited Itk's activity with an IC50 in the nanomolar range. Compound 44 substantially reduced proinflammatory immune responses in vitro and in vivo after systemic administration in two acute CHS models. In addition,our data reveal that human Itk,comparable to its murine homologue,is expressed mainly in T cells and is increased in lesional skin from patients with atopic dermatitis and allergic contact dermatitis. Finally,silencing of Itk by RNA interference in primary human T cells efficiently blocks TCR-induced lymphokine secretion. In conclusion,Itk represents an interesting new target for the therapy of T-cell-mediated inflammatory skin diseases. View Publication

Retinoic acid (RA) imprints gut-homing specificity on T cells upon activation by inducing the expression of chemokine receptor CCR9 and integrin α4β7. CCR9 expression seemed to be more highly dependent on RA than was the α4β7 expression,but its molecular mechanism remained unclear. In this article,we show that NFAT isoforms NFATc1 and NFATc2 directly interact with RA receptor (RAR) and retinoid X receptor (RXR) but play differential roles in RA-induced CCR9 expression on murine naive CD4(+) T cells. TCR stimulation for 6-24 h was required for the acquisition of responsiveness to RA and induced activation of NFATc1 and NFATc2. However,RA failed to induce CCR9 expression as long as TCR stimulation continued. After terminating TCR stimulation or adding cyclosporin A to the culture,Ccr9 gene transcription was induced,accompanied by inactivation of NFATc1 and sustained activation of NFATc2. Reporter and DNA-affinity precipitation assays demonstrated that the binding of NFATc2 to two NFAT-binding sites and that of the RAR/RXR complex to an RA response element half-site in the 5'-flanking region of the mouse Ccr9 gene were critical for RA-induced promoter activity. NFATc2 directly bound to RARα and RXRα,and it enhanced the binding of RARα to the RA response element half-site. NFATc1 also bound to the NFAT-binding sites and directly to RARα and RXRα,but it inhibited the NFATc2-dependent promoter activity. These results suggest that the cooperativity between NFATc2 and the RAR/RXR complex is essential for CCR9 expression on T cells and that NFATc1 interferes with the action of NFATc2. View Publication

Chimerism analysis has become an important tool to manage patients in the peri-transplant period of allogenic stem cell transplantation. During this period,cells of donor and host origin can coexist and increasing proportion of cells of host origin is considered as a recurrence of the underlying disease. We currently performed chimerism analysis on separate peripheral blood cell subsets,lymphocytes and granulocytes. To improve our isolation method,a new automated device from Stem Cell Technology Roboseptrade mark was tested and compared to our manual separation technique. The results obtained on T cell purification showed an improvement of the purity (98.42% with Robosep vs. 92.42% with the manual technique Rosettesep) and of the recovery (63.43% with Robosep and 38% with Rosettesep). The results were significantly improved on patient samples with less than 10% CD3 positive cells (purity: 90% vs. 44.44%; recovery: 73.79% vs. 43.98%). Granulocytes separation was based on CD15 expression. The results showed an improvement of the purity with Robosep (96.90% vs. 86.20% with the manual technique Polymorphprep) but the recovery was impaired (35.2% vs. 52.30%). Using a myeloid (CD66/CD33) cocktail,recovery was improved with the Robosep device (64.04% with the myeloid cocktail vs. 22.4% with the CD15 cocktail). Our data demonstrated that Robosep allowed a performant cell purification in the early period post-transplantation even for populations representing less than 10% of the peripheral blood cells. View Publication

Costimulatory signals are critical to T cell activation,but how their effects are mediated remains incompletely characterized. Here,we demonstrate that locally produced C5a and C3a anaphylatoxins interacting with their G protein-coupled receptors (GPCRs),C5aR and C3aR,on APCs and T cells both upstream and downstream of CD28 and CD40L signaling are integrally involved in T cell proliferation and differentiation. Disabling these interactions reduced MHC class II and costimulatory-molecule expression and dramatically diminished T cell responses. Importantly,impaired T cell activation by Cd80-/-Cd86-/- and Cd40-/- APCs was reconstituted by added C5a or C3a. C5aR and C3aR mediated their effects via PI-3 kinase-gamma-dependent AKT phosphorylation,providing a link between GPCR signaling,CD28 costimulation,and T cell survival. These local paracrine and autocrine interactions thus operate constitutively in naive T cells to maintain viability,and their amplification by cognate APC partners thus is critical to T cell costimulation. View Publication

Exposure to Mycobacterium tuberculosis (Mtb) results in heterogeneous clinical outcomes including primary progressive tuberculosis and latent Mtb infection (LTBI). Mtb infection is identified using the tuberculin skin test and interferon-gamma (IFN-gamma) release assay IGRA,and a positive result may prompt chemoprophylaxis to prevent progression to tuberculosis. In the present study,we report on a cohort of Ugandan individuals who were household contacts of patients with TB. These individuals were highly exposed to Mtb but tested negative disease by IFN-gamma release assay and tuberculin skin test,'resisting' development of classic LTBI. We show that 'resisters' possess IgM,class-switched IgG antibody responses and non-IFN-gamma T cell responses to the Mtb-specific proteins ESAT6 and CFP10,immunologic evidence of exposure to Mtb. Compared to subjects with classic LTBI,'resisters' display enhanced antibody avidity and distinct Mtb-specific IgG Fc profiles. These data reveal a distinctive adaptive immune profile among Mtb-exposed subjects,supporting an expanded definition of the host response to Mtb exposure,with implications for public health and the design of clinical trials. View Publication

How environmental factors combine with genetic risk at the molecular level to promote complex trait diseases such as multiple sclerosis (MS) is largely unknown. In mice,N-glycan branching by the Golgi enzymes Mgat1 and/or Mgat5 prevents T cell hyperactivity,cytotoxic T-lymphocyte antigen 4 (CTLA-4) endocytosis,spontaneous inflammatory demyelination and neurodegeneration,the latter pathologies characteristic of MS. Here we show that MS risk modulators converge to alter N-glycosylation and/or CTLA-4 surface retention conditional on metabolism and vitamin D(3),including genetic variants in interleukin-7 receptor-α (IL7RA*C),interleukin-2 receptor-α (IL2RA*T),MGAT1 (IV(A)V(T-T)) and CTLA-4 (Thr17Ala). Downregulation of Mgat1 by IL7RA*C and IL2RA*T is opposed by MGAT1 (IV(A)V(T-T)) and vitamin D(3),optimizing branching and mitigating MS risk when combined with enhanced CTLA-4 N-glycosylation by CTLA-4 Thr17. Our data suggest a molecular mechanism in MS whereby multiple environmental and genetic inputs lead to dysregulation of a final common pathway,namely N-glycosylation. View Publication