Project description:Ligation of the B cell antigen receptor (BCR) initiates humoral immunity. However, mere BCR signaling without appropriate co-stimulation commits B cells to death rather than to differentiation into immune effector cells. How BCR activation depletes potentially autoreactive B cells while simultaneously primes for receiving rescue and differentiation signals from cognate T lymphocytes remains unknown. Here, using a mass spectrometry-based proteomic approach to identify cytosolic/nuclear shuttling elements, we uncover transcription factor EB (TFEB) as a central BCR-controlled rheostat that drives activation-induced apoptosis, and concurrently, promotes the reception of co-stimulatory rescue signals by supporting B cell migration and antigen presentation. CD40 co-stimulation prevents TFEB-driven cell death, while enhancing and prolonging TFEB’s nuclear residency, which hallmarks antigenic experience also of memory B cells. In mice, TFEB shapes the transcriptional landscape of germinal center B cells. Within the germinal center, TFEB facilitates the dark zone entry of light-zone-residing centrocytes through regulation of chemokine receptors and, by balancing the expression of Bcl-2/BH3-only family members, integrates antigen-induced apoptosis with T cell-provided CD40 survival signals. Thus, TFEB reprograms antigen-primed germinal center B cells for cell fate decisions.
Project description:Purpose:Flow cytometric analysis showed that after 48h of culture with T cell- and Ag-derived stimuli, GCBC alter their TF expression and begin to differentiate. However, only a subset of cells undergoes this process, for reasons that are unclear. To better define the nature of this heterogeneity, and to further define the differences between IL-21R/CD40 vs BCR/CD40 signals, we performed single cell RNA-seq (scRNA-seq) of 48h GCBC cultures with either of these two stimuli or with the combination of IL-21R/CD40 and BCR stimulation. Methods: we performed scRNA-seq using 10X Genomics Chromium system . Results: Single cell analysis demonstrated surprisingly little overlap between the clusters derived from IL-21/⍺-CD40 stimulation and those derived from BCR/⍺-CD40 ligation, thus establishing at molecular and cellular detail how distinct these two types of selection signals are for GCBC
Project description:Purpose: To gain insight into both similarities and differences in the gene expression programs induced by IL-21R, BCR and CD40 signals, we performed RNA-seq on both GCBC and NBC that had been stimulated for either 2h or 4h with IL-21, CD40 ligation, BCR ligation, or combinations of these. Methods : Purified GCBC from d14 NP-CGG immunized MEG mice and NBC from naïve MEG mice were warmed at 37C for 30 minutes and then stimulated with 10ng/mL IL-21, 20μg/ml ⍺-IgM or 2.5μg/mL ⍺-CD40 (prepared as tetramer) alone or combined IL21/⍺-CD40 or ⍺-IgM/⍺-CD40 for 2 and 4 hours. After stimulation, cells were processed for RNA isolation using QIAshredder columns (Qiagen) and the RNeasy Plus Mini Kit (Qiagen) following the manufacturer’s instructions. Samples were sequenced using Illumina NextSeq 500 with 75 bp paired-end reads and aligned to the mm10 genome using the STAR aligner (Dobin et al., 2013). Gene-level counts were determined using featureCounts (Liao et al., 2014), and raw counts were quantile normalized to each other for differential expression using the voom method (Law et al., 2014) in the Limma R package (Ritchie et al., 2015). For normalization of the datasets, the Quantile method was used. Results: Like BCR and CD40 signals, IL-21R plus CD40 signals also synergize to induce c-Myc in GCBC. However, IL-21R plus CD40 stimulation differentially affects GCBC fate compared to BCR plus CD40 ligation—engaging unique molecular mechanisms
Project description:Background & Aims: The precise mechanism underlying the attenuation of the antigen-specific B cell response induced by therapeutic vaccination during chronic HBV infection remains unclear. The development of vaccines or strategies targeting this impediment through rational design could potentially result in significant advancements in the treatment of chronic hepatitis B. Methods: A mouse model with a knock-in of a B cell receptor specific to the hepatitis B virus surface antigen was generated under the name E6F6-B. This model was utilized to investigate the temporal and spatial patterns of humoral responses induced by therapeutic vaccination in the presence of persistent antigen stimulation. Through the use of multiple transcriptome sequencing techniques, the differentiation trajectory of HBsAg-specific B cells post therapeutic vaccination during chronic hepatitis B infection was elucidated. Results: In light of the E6F6-B transfer model, a significant reduction in antibody secreting cells were observed two weeks after vaccination. Additionally, an atypical pre-plasma cell population (BLIMP-1+ IRF4+ CD40- CD138-) was identified as a consequence of persistent BCR signaling in the absence of CD40 co-stimulation. A therapeutic antibody-induced suppression of BCR signaling revitalized the HBsAg-specific B cell response.
Project description:Background & Aims: The precise mechanism underlying the attenuation of the antigen-specific B cell response induced by therapeutic vaccination during chronic HBV infection remains unclear. The development of vaccines or strategies targeting this impediment through rational design could potentially result in significant advancements in the treatment of chronic hepatitis B. Methods: A mouse model with a knock-in of a B cell receptor specific to the hepatitis B virus surface antigen was generated under the name E6F6-B. This model was utilized to investigate the temporal and spatial patterns of humoral responses induced by therapeutic vaccination in the presence of persistent antigen stimulation. Through the use of multiple transcriptome sequencing techniques, the differentiation trajectory of HBsAg-specific B cells post therapeutic vaccination during chronic hepatitis B infection was elucidated. Results: In light of the E6F6-B transfer model, a significant reduction in antibody secreting cells were observed two weeks after vaccination. Additionally, an atypical pre-plasma cell population (BLIMP-1+ IRF4+ CD40- CD138-) was identified as a consequence of persistent BCR signaling in the absence of CD40 co-stimulation. A therapeutic antibody-induced suppression of BCR signaling revitalized the HBsAg-specific B cell response.
Project description:Endometrial receptivity on genomic level is one of the major cause of implantation failure in IVF patients with unexlained infertility and is a main obstacle in success of IVF. Gene expression profiles of implantation failure cases of unexplained infertility were compared with proven healthy oocyte donors as controls, both undergoing ovarian stimulation. The results provide additional information about gene expression profile related to endometrial receptivity in implantation failure cases especially under the influence of ovarian stimulation during IVF cycle.
Project description:Endometrial receptivity on genomic level is one of the major cause of implantation failure in IVF patients with unexplained infertility and is a main obstacle in success of IVF. Gene expression profiles of implantation failure cases of unexplained infertility were compared with proven healthy oocyte donors as controls, both undergoing ovarian stimulation. The results provide additional information about gene expression profile related to endometrial receptivity in implantation failure cases especially under the influence of ovarian stimulation during IVF cycle.
Project description:Survival of all B cells depends on signals from the B-cell receptor (BCR). In BCRnegative B cells the latent membrane protein 2A (LMP2A) of Epstein-Barr virus (EBV) replaces this survival signal and might play a role in the development of EBV-positive Hodgkin lymphomas and posttransplantation lymphoproliferative disease. In these BCR-negative cells LMP2A provides a ‘tonic’ signal similar to BCR’s constitutive expression in the absence of antigen in order to maintain activating signaling pathways common to both receptor molecules. In most latently EBV-infected B cells LMP2A and BCR are co-expressed but it is largely unclear what LMP2A contributes with respect to B-cell activation, proliferation and viral latency in these BCR-positive cells. A common model suggests that LMP2A maintains herpesviral latency by blocking BCR-mediated signals but how LMP2A could serve both antithetical ends in BCRnegative and BCR-positive cells is elusive. Our comparative analysis of BCR and LMP2A now indicates that LMP2A is a true BCR mimic that dominates BCR-operated signaling pathways in EBV-infected, BCR-positive cells to provide activation signals, support stable infections in vivo and allow exit from latency. These findings suggest that LMP2A co-opts the situation in anergic B cells, where continuous BCR signaling results in maintenance of the anergic state accompanied by unresponsiveness to acute BCR stimulation. The microarray experiment was used to compare effects of BCR and LMP2A on gene expression regulation. EBV's LMP2A and the human BCR activate similar cellular target genes; some genes are regulated solely by BCR or LMP2A, no gene is counter regulated A 12 chip study using cDNA from three separate 2525 LMP2A knockout LCL cultures and three separate 3696.10 LMP2A:mCD69 LCL cultures; each culture tested before and after 90 min stimulation of the BCR and LMP2A:mCD69, respectively.
Project description:Following combined stimulation through Toll-like receptor (TLR)-9 and the B-cell receptor (BCR), human B cells were sorted based on IL-10 expression. Microarray analysis showed that just ~0.7% of genes were differentially expressed between IL-10- and IL-10+ B-cells. However, connectivity map analysis revelaed that the IL-10+ cells were those undergoing differentiation to germincal centre B cells, and we identified a CD11c- B-cell subset that was enriched in cells capable of producing IL-10