Molecular pathway profiling of T lymphocyte signal transduction pathways; Th1 and Th2 genomic fingerprints are defined by TCR and CD28-mediated signaling

Contains fulltext : 108719.pdf (publisher's version ) (Open Access)BACKGROUND: T lymphocytes are orchestrators of adaptive immunity. Naive T cells may differentiate into Th1, Th2, Th17 or iTreg phenotypes, depending on environmental co-stimulatory signals. To identify genes and pathways involved in differentiation of Jurkat T cells towards Th1 and Th2 subtypes we performed comprehensive transcriptome analyses of Jurkat T cells stimulated with various stimuli and pathway inhibitors. Results from these experiments were validated in a human experimental setting using whole blood and purified CD4+ Tcells. RESULTS: Calcium-dependent activation of T cells using CD3/CD28 and PMA/CD3 stimulation induced a Th1 expression profile reflected by increased expression of T-bet, RUNX3, IL-2, and IFNgamma, whereas calcium-independent activation via PMA/CD28 induced a Th2 expression profile which included GATA3, RXRA, CCL1 and Itk. Knock down with siRNA and gene expression profiling in the presence of selective kinase inhibitors showed that proximal kinases Lck and PKCtheta are crucial signaling hubs during T helper cell activation, revealing a clear role for Lck in Th1 development and for PKCtheta in both Th1 and Th2 development. Medial signaling via MAPkinases appeared to be less important in these pathways, since specific inhibitors of these kinases displayed a minor effect on gene expression. Translation towards a primary, whole blood setting and purified human CD4+ T cells revealed that PMA/CD3 stimulation induced a more pronounced Th1 specific, Lck and PKCtheta dependent IFNgamma production, whereas PMA/CD28 induced Th2 specific IL-5 and IL-13 production, independent of Lck activation. PMA/CD3-mediated skewing towards a Th1 phenotype was also reflected in mRNA expression of the master transcription factor Tbet, whereas PMA/CD28-mediated stimulation enhanced GATA3 mRNA expression in primary human CD4+ Tcells. CONCLUSIONS: This study identifies stimulatory pathways and gene expression profiles for in vitro skewing of T helper cell activation. PMA/CD3 stimulation enhances a Th1-like response in an Lck and PKCtheta dependent fashion, whereas PMA/CD28 stimulation results in a Th2-like phenotype independent of the proximal TCR-tyrosine kinase Lck. This approach offers a robust and fast translational in vitro system for skewed T helper cell responses in Jurkat T cells, primary human CD4+ Tcells and in a more complex matrix such as human whole blood

Effects of pulse shape and polarity on sensitivity to cochlear implant stimulation: a chronic study in guinea pigs

International audienc

Altered Cortical Activity in Prelingually Deafened Cochlear Implant Users Following Long Periods of Auditory Deprivation

Auditory stimulation during childhood is critical for the development of the auditory cortex in humans and with that for hearing in adulthood. Age-related changes in morphology and peak latencies of the cortical auditory evoked potential (CAEP) have led to the use of this cortical response as a biomarker of auditory cortical maturation including studies of cortical development after deafness and subsequent cochlear implantation. To date, it is unknown whether prelingually deaf adults, with early onset deafness (before the age of 2 years) and who received a cochlear implant (CI) only during adulthood, would display absent or aberrant CAEP waveforms as predicted from CAEP studies in late implanted prelingually deaf children. In the current study, CAEP waveforms were recorded in response to electric stimuli in prelingually deaf adults, who received their CI after the age of 21 years. Waveform morphology and peak latencies were compared to the CAEP responses obtained in postlingually deaf adults, who became deaf after the age of 16. Unexpectedly, typical CAEP waveforms with adult-like P1-N1-P2 morphology could be recorded in the prelingually deaf adult CI users. On visual inspection, waveform morphology was comparable to the CAEP waveforms recorded in the postlingually deaf CI users. Interestingly, however, latencies of the N1 peak were significantly shorter and amplitudes were significantly larger in the prelingual group than in the postlingual group. The presence of the CAEP together with an early and large N1 peak might represent activation of the more innate and less complex components of the auditory cortex of the prelingually deaf CI user, whereas the CAEP in postlingually deaf CI users might reflect activation of the mature neural network still present in these patients. The CAEPs may therefore be helpful in the assessment of developmental state of the auditory cortex