Peptide-induced negative selection of thymocytes activates transcription of an NF-kappa B inhibitor

Negative selection eliminates thymocytes bearing autoreactive T cell receptors (TCR) via an apoptotic mechanism. We have cloned an inhibitor of NF-kappa B, I kappa BNS, which is rapidly expressed upon TCR-triggered but not dexamethasone- or gamma irradiation-stimulated thymocyte death. The predicted protein contains seven ankyrin repeats and is homologous to I kappa B family members. In class I and class II MHC-restricted TCR transgenic mice, transcription of I kappa BNS is stimulated by peptides that trigger negative selection but not by those inducing positive selection (i.e., survival) or nonselecting peptides. I kappa BNS blocks transcription from NF-kappa B reporters, alters NF-kappa B electrophoretic mobility shifts, and interacts with NF-kappa B proteins in thymic nuclear lysates following TCR stimulation. Retroviral transduction of I kappa BNS in fetal thymic organ culture enhances TCR-triggered cell death consistent with its function in selection

Can the fatty acids profile of Tuber aestivum - T. uncinatum species complex have chemotaxonomic value?

Fatty acid (FA) profiles are considered as chemotaxonomic markers to define groups of various taxonomic ranks in bacteria, yeasts, and fungi. Tuber aestivum is one of the most common European truffles that has environmental and economic values. While genetic studies suggest that T. aestivum Vittad. and T. uncinatum Chatin are synonymous, there is still debate over whether this is a species complex. In this work, we evaluate the differences in the total and individual FAs content of T. aestivum and T. uncinatum morphotypes, and T. melanosporum n-hexane extracts. The higher amounts of total linoleic acid and total oleic acid are found in T. uncinatum and characterize it from the T. aestivum. The composition of FA profiles of T. uncinatum-T. aestivum were distinguished by the presence of free palmitoleic acid (a chemotaxonomic marker) in T. uncinatum and absent in T. aestivum. Cluster analysis indicated that there were two groups for the FA profiles of the Tuber spp. hexanic extract: T. aestivum extract and T. uncinatum and T. melanosporum extracts. Our results indicate that T. aestivum and T. uncinatum have to be considered as two different taxa within the T. aestivum species complex

Gene transfer of soluble interleukin-17 receptor prolongs cardiac allograft survival in a rat model

Objective: Interleukin-17 (IL-17), a potent proinflammatory cytokine, has been implicated in allograft rejection. We analyzed the efficacy of an adenoviral vector expressing an IL-17 inhibitor in delaying acute allograft rejection in a rat model of heart transplantation, and the biological mechanisms underlying the protective effect. Methods: We constructed an adenoviral vector expressing a soluble IL-17 receptor-immunoglobulin (IL-17R-Ig) fusion protein. IL-17R-Ig activity was assessed by inhibition of IL-17-induced IL-6 release in HeLa cells preincubated with the vector. Intracoronary vector administration was performed in F344 donor hearts that were placed as vascularized grafts into Lewis hosts. Inflammatory cells infiltrating the graft were analyzed by immunohistology. Cytokine transcripts in the graft were determined by real-time RT-PCR. Results: IL-17R-Ig gene transfer resulted in prolonged allograft survival (16.1 ± 3.1 days vs 10.3 ± 2.5 days with control virus and 10.1 ± 2.1 days with virus dilution buffer alone; p ≪ 0.001). IL-17R-Ig gene transfer reduced inflammatory cell infiltrates, especially monocytes/macrophages and CD4+ T cells (p ≪ 0.05). It also reduced intragraft cytokine transcripts for interferon-γ and transforming growth factor-β (p ≪ 0.05) and, to a lesser extent, IL-1β and tumor necrosis factor-α (p = 0.083). Conclusions: Local expression of soluble IL-17 receptor-immunoglobulin attenuates T helper type 1 (Th1) cytokine responses and leukocyte infiltration in rat cardiac allografts, thereby mediating prolonged graft survival. Intragraft IL-17 inhibition may be useful as an adjuvant therapy to systemic immunosuppression in heart transplantatio

Adhesion of Immature and Mature T Cells Induces in Human Thymic Epithelial Cells (TEC) Activation of IL-6 Gene Trascription Factors (NF-κB And NF-IL6) and IL-6 Gene Expression : Role of αtβ1 and α6β4 Integrins

T cell precursors homed to thymus develop in close contact with stromal cells. Among them, thymic epithelial cells (TEC) are known to exert dominant roles in their survival and functional shaping. Key molecules mediating TEC/thymocytes interactions include cytokines and growth factors secreted by the two cell types and adhesion receptors mediating cell contact. Signaling events triggered in thymocytes by adhesion to epithelial cells have been extensively investigated, whereas little is known on the opposite phenomenon. We have previously investigated this issue in a co-culture system composed of TEC cultures derived from human normal thymus and heterologous thymocytes. We demonstrated that thymocytes adhere to TEC involving β1 and β4 integrins and induce the clustering of (α3β1 and α6β4 heterodimers at the TEC surface. In addition thymocyte adhesion was followed by activation of NF-κB and NF-IL6 gene transciption factors and enhanced IL-6 production. The two latter phenomena were reproduced by the cross-linking of the α3, α6, β1 and β4 integrins, thus implying that the α3β1 and α6β4 heterodimers can signal during thymocyte adhesion. We have extended our previous work investigating in the same experimental setting the inducing activity of non stimulated or activated policlonal or clonal mature T cells as representative of the more mature thymocyte subset. We found that adhesion of unstimulated T cell i) involved β1, but not β4 integrin functions at the surface ii) induced the clustering of α3β1 , but not α2β1 heterodimers at the TEC surface and iii) up-regulated the nuclear binding activity of NF-κB transcription factor and the IL-6 secretion. We propose that α3β1 and α6β4 heterodimers are induced to cluster at the TEC surface recognizing yet unknown cellular ligands differentially expressed during T cell development

Delta-like 4 is the essential, nonredundant ligand for Notch1 during thymic T cell lineage commitment

Thymic T cell lineage commitment is dependent on Notch1 (N1) receptor–mediated signaling. Although the physiological ligands that interact with N1 expressed on thymic precursors are currently unknown, in vitro culture systems point to Delta-like 1 (DL1) and DL4 as prime candidates. Using DL1- and DL4-lacZ reporter knock-in mice and novel monoclonal antibodies to DL1 and DL4, we show that DL4 is expressed on thymic epithelial cells (TECs), whereas DL1 is not detected. The function of DL4 was further explored in vivo by generating mice in which DL4 could be specifically inactivated in TECs or in hematopoietic progenitors. Although loss of DL4 in hematopoietic progenitors did not perturb thymus development, inactivation of DL4 in TECs led to a complete block in T cell development coupled with the ectopic appearance of immature B cells in the thymus. These immature B cells were phenotypically indistinguishable from those developing in the thymus of conditional N1 mutant mice. Collectively, our results demonstrate that DL4 is the essential and nonredundant N1 ligand responsible for T cell lineage commitment. Moreover, they strongly suggest that N1-expressing thymic progenitors interact with DL4-expressing TECs to suppress B lineage potential and to induce the first steps of intrathymic T cell development

Seizures-like symptoms in an African child with life-threatening severe upper respiratory tract obstruction

Obstructive sleep apneas are characterized by episodes of complete or partial upper airway obstruction during sleep. Symptoms and signs are associated with sleep-related breathing disorders. Sometimes it can be clinically difficult to distinguish abnormal events related to sleep disorders from seizures. We report herein the case of a child with seizures-like symptoms during sleep.Epilepsy was excluded and symptomatology was referred to life-threatening upper respiratory obstruction from tonsils and adenoids hypertrophy that required persistent intubation before surgical removal

Modeling Alzheimer’s disease related phenotypes in the Ts65Dn mouse: impact of age on Aβ, Tau, pTau, NfL, and behavior

IntroductionPeople with DS are highly predisposed to Alzheimer’s disease (AD) and demonstrate very similar clinical and pathological features. Ts65Dn mice are widely used and serve as the best-characterized animal model of DS.MethodsWe undertook studies to characterize age-related changes for AD-relevant markers linked to Aβ, Tau, and phospho-Tau, axonal structure, inflammation, and behavior.ResultsWe found age related changes in both Ts65Dn and 2N mice. Relative to 2N mice, Ts65Dn mice showed consistent increases in Aβ40, insoluble phospho-Tau, and neurofilament light protein. These changes were correlated with deficits in learning and memory.DiscussionThese data have implications for planning future experiments aimed at preventing disease-related phenotypes and biomarkers. Interventions should be planned to address specific manifestations using treatments and treatment durations adequate to engage targets to prevent the emergence of phenotypes

Hematopoiesis under telomere attrition at the single-cell resolution

The molecular mechanisms that drive hematopoietic stem cell functional decline under conditions of telomere shortening are not completely understood. In light of recent advances in single-cell technologies, we sought to redefine the transcriptional and epigenetic landscape of mouse and human hematopoietic stem cells under telomere attrition, as induced by pathogenic germline variants in telomerase complex genes. Here, we show that telomere attrition maintains hematopoietic stem cells under persistent metabolic activation and differentiation towards the megakaryocytic lineage through the cell-intrinsic upregulation of the innate immune signaling response, which directly compromises hematopoietic stem cells’ self-renewal capabilities and eventually leads to their exhaustion. Mechanistically, we demonstrate that targeting members of the Ifi20x/IFI16 family of cytosolic DNA sensors using the oligodeoxynucleotide A151, which comprises four repeats of the TTAGGG motif of the telomeric DNA, overcomes interferon signaling activation in telomere-dysfunctional hematopoietic stem cells and these cells’ skewed differentiation towards the megakaryocytic lineage. This study challenges the historical hypothesis that telomere attrition limits the proliferative potential of hematopoietic stem cells by inducing apoptosis, autophagy, or senescence, and suggests that targeting IFI16 signaling axis might prevent hematopoietic stem cell functional decline in conditions affecting telomere maintenance