Project description:Follicular helper T cells (Tfh) is indispensable for T-cell dependent antibody responses. Understanding the underlying mechanisms of their differentiation and function is critical for vaccine development. Using unique gene array analysis, we identified adenosine deaminase-1 (ADA-1), as a novel key molecule that drives Tfh helper program in proliferating germinal centers Tfh and circulatory Tfh cells following their interactions with B cells. ADA-1 expression and enzymatic activity is significantly higher in Tfh cells when compared to non-Tfh cells. Exogenous ADA-1 enhances the ability of less efficient cTfh and pro-follicular Tfh cells to provide B cell help, while pharmacological inhibition of ADA-1 activity impeded Tfh function and blunted antibody response. Importantly, in vivo use of recombinant ADA-1 as an adjuvant in a DNA-based HIV vaccine enhanced Tfh differentiation and improved the quantity and the quality of HIV-specific antibody response. Thus, ADA-1 represents a good target for the design of new vaccine strategy.
Project description:Follicular helper T cells (Tfh) is indispensable for T-cell dependent antibody responses. Understanding the underlying mechanisms of their differentiation and function is critical for vaccine development. Using unique gene array analysis, we identified adenosine deaminase-1 (ADA-1), as a novel key molecule that drives Tfh helper program in proliferating germinal centers Tfh and circulatory Tfh cells following their interactions with B cells. ADA-1 expression and enzymatic activity is significantly higher in Tfh cells when compared to non-Tfh cells. Exogenous ADA-1 enhances the ability of less efficient cTfh and pro-follicular Tfh cells to provide B cell help, while pharmacological inhibition of ADA-1 activity impeded Tfh function and blunted antibody response. Importantly, in vivo use of recombinant ADA-1 as an adjuvant in a DNA-based HIV vaccine enhanced Tfh differentiation and improved the quantity and the quality of HIV-specific antibody response. Thus, ADA-1 represents a good target for the design of new vaccine strategy.
Project description:COVID-19 mRNA vaccines generate high concentrations of circulating anti-Spike antibodies and Spike-specific CD4+ T cells following prime-boost vaccination. It is not yet clear if vaccine-induced CD4+ T cell responses in the draining lymph node contribute to this outstanding immunogenicity. Using fine needle aspiration of draining axillary lymph nodes from individuals who received the BNT162b2 mRNA vaccine, we found large populations of Spike-specific CD4+ T follicular helper cells in the draining lymph node. A broadly immunodominant HLA-DPB1*04-restricted response to Spike166-180 composes one of the largest populations of T follicular helper cells in individuals with this allele, which is itself among the most common HLA alleles in the human population. Spike-specific T follicular helper cells are present in the lymph node 30 days after vaccine boost and persist in some individuals more than 170 days. Collectively, our results underscore the key role that robust T follicular helper cell responses play in the establishment of long-term immunity in this very efficacious human vaccine.
Project description:We have recently demonstrated that the function of T follicular helper (Tfh) cells obtained from lymph nodes (LN) of HIV-infected individuals is impaired. We found that these cells were unable to provide proper help to germinal center (GC)-B cells, as observed by altered and inefficient anti-HIV antibody response and premature death of memory B cells. The underlying molecular mechanisms of this dysfunction remain poorly defined. Herein, we have used a unique transcriptional approach to identify these molecular defects. We consequently determined the transcriptional profiles of LN GC-Tfh cells following their interactions with LN GC-B cells from HIV-infected and HIV-uninfected individuals, rather than analyzing resting ex-vivo GC-Tfh cells. We observed that proliferating HIV-infected GC-Tfh cells were transcriptionally different than those from HIV-uninfected individuals, displaying a significant downregulation of immune- and GC-Tfh-associated pathways and genes compared to cells from uninfected individuals. Our results strongly demonstrated that MAF (coding for the transcription factor c-Maf) and its upstream signaling pathway mediators (IL6R and STAT3) were significantly downregulated in HIV-infected subjects, which could contribute to the impaired GC-Tfh and GC-B cell functions reported during infection. We further showed that c-Maf function was associated with the adenosine pathway and that the signaling upstream c-Maf could be partially restored by adenosine deaminase -1 (ADA-1) supplementation. Overall, we identified a novel mechanism that contributes to GC-Tfh impairment during HIV infection. Understanding how GC-Tfh function is altered in HIV is crucial and could provide critical information about the mechanisms leading to the development and maintenance of effective anti-HIV antibodies.
Project description:We have recently demonstrated that the function of T follicular helper (Tfh) cells obtained from lymph nodes (LN) of HIV-infected individuals is impaired. We found that these cells were unable to provide proper help to germinal center (GC)-B cells, as observed by altered and inefficient anti-HIV antibody response and premature death of memory B cells. The underlying molecular mechanisms of this dysfunction remain poorly defined. Herein, we have used a unique transcriptional approach to identify these molecular defects. We consequently determined the transcriptional profiles of LN GC-Tfh cells following their interactions with LN GC-B cells from HIV-infected and HIV-uninfected individuals, rather than analyzing resting ex-vivo GC-Tfh cells. We observed that proliferating HIV-infected GC-Tfh cells were transcriptionally different than those from HIV-uninfected individuals, displaying a significant downregulation of immune- and GC-Tfh-associated pathways and genes compared to cells from uninfected individuals. Our results strongly demonstrated that MAF (coding for the transcription factor c-Maf) and its upstream signaling pathway mediators (IL6R and STAT3) were significantly downregulated in HIV-infected subjects, which could contribute to the impaired GC-Tfh and GC-B cell functions reported during infection. We further showed that c-Maf function was associated with the adenosine pathway and that the signaling upstream c-Maf could be partially restored by adenosine deaminase -1 (ADA-1) supplementation. Overall, we identified a novel mechanism that contributes to GC-Tfh impairment during HIV infection. Understanding how GC-Tfh function is altered in HIV is crucial and could provide critical information about the mechanisms leading to the development and maintenance of effective anti-HIV antibodies.
Project description:Immune evasion is a critical step of cancer progression that remains a major obstacle for current T cell-based immunotherapies. Hence, we seek to genetically reprogram T cells to exploit a common tumor-intrinsic evasion mechanism, whereby cancer cells suppress T cell function by generating a metabolically unfavorable tumor microenvironment (TME). Specifically, we use an in silico screen to identify ADA and PDK1 as metabolic regulators, in which gene overexpression (OE) enhances the cytolysis of CD19-specific CD8 CAR-T cells against cognate leukemia cells, and conversely, ADA or PDK1 deficiency dampens such effect. Additionally, ADA-OE in CAR-T cells improves cancer cytolysis under high concentrations of adenosine, the ADA substrate and an immunosuppressive metabolite in the TME. High-throughput transcriptomics and metabolomics in these CAR-Ts reveal alterations of global gene expression and metabolic signatures in both ADA- and PDK1- engineered CAR-T cells. Functional and immunological analyses demonstrate that ADA-OE increases proliferation and decreases exhaustion in α-CD19 and α-HER2 CAR-T cells. We then show ADA-OE improves tumor infiltration and clearance by α-HER2 CD4 and CD8 CAR-T with an in vivo colorectal cancer model. Collectively, these data unveil systematic knowledge of metabolic reprogramming directly in CAR-T cells, and reveal potential targets for improving CAR-T based cell therapy.
Project description:Immune evasion is a critical step of cancer progression that remains a major obstacle for current T cell-based immunotherapies. Hence, we seek to genetically reprogram T cells to exploit a common tumor-intrinsic evasion mechanism, whereby cancer cells suppress T cell function by generating a metabolically unfavorable tumor microenvironment (TME). Specifically, we use an in silico screen to identify ADA and PDK1 as metabolic regulators, in which gene overexpression (OE) enhances the cytolysis of CD19-specific CD8 CAR-T cells against cognate leukemia cells, and conversely, ADA or PDK1 deficiency dampens such effect. Additionally, ADA-OE in CAR-T cells improves cancer cytolysis under high concentrations of adenosine, the ADA substrate and an immunosuppressive metabolite in the TME. High-throughput transcriptomics and metabolomics in these CAR-Ts reveal alterations of global gene expression and metabolic signatures in both ADA- and PDK1- engineered CAR-T cells. Functional and immunological analyses demonstrate that ADA-OE increases proliferation and decreases exhaustion in α-CD19 and α-HER2 CAR-T cells. We then show ADA-OE improves tumor infiltration and clearance by α-HER2 CD4 and CD8 CAR-T with an in vivo colorectal cancer model. Collectively, these data unveil systematic knowledge of metabolic reprogramming directly in CAR-T cells, and reveal potential targets for improving CAR-T based cell therapy.
Project description:Epstein-Barr Virus (EBV) immortalizes resting B-lymphocytes through a highly orchestrated process involving extensive reprogramming of host transcription and metabolism. Here, we use multiple omics-based approaches concurrently across the time course of B-cell infection to investigate the underlying mechanisms that control EBV-induced B-cell immortalization. ATAC-seq revealed that over a third of accessible chromatin is altered with the most perturbed sites overlapping Ets-family, including PU.1 and RUNX1 transcription factors. EBV nuclear antigens (EBNAs) clustered with different gene categories and RNA-seq identified the transcriptional response of these gene. Focusing on EBNA1 revealed a selection of gene targets involved in nucleotide metabolism. Metabolomics indicated that adenosine and purine metabolism are significantly altered by EBV immortalization, and we validated that adenosine deaminase (ADA) is a direct and critical target of EBNA1 and the EBV-directed immortalization process. These findings reveal that purine metabolism and ADA inhibitors may be a useful therapeutic for EBV-driven lymphoid cancers