Project description:Bryostatin-1, a pharmacological agent from marine organisms, has been studied for HIV and cancer therapies due to its modulation of protein kinase C. In our previous study (Zhao M et al. Pharmacological research. 2019;139:524-34.), we found that bryostatin-1 downregulated inhibitory receptor PD-1 on activated CD8+ T cells from people with HIV. Since HIV-specific CD8+ T cells become functionally exhausted during chronic HIV infection and PD-1 expression is known to be related to the exhaustion state of these cells, we hypothesized that bryostatin-1 may modulate CD8+ T cell exhaustion. To test this, we generated in vitro exhausted OT-I CD8+ T cells as previously described (Zhao M et al PLoS Pathog. 16(6): e1008555) by repeatedly stimulating cells with OVA(257-264) peptide. Then we treated both exhausted CD8+ T cells (repeat peptide stimulated cells) and non-exhausted CD8+ T cells (single peptide stimulated cells) with bryostatin-1 for 3 days. We found that bryostatin-1 decreased exhaustion-associated markers and improved the functionality of exhausted CD8+ T cells. To investigate the underlying mechanism of how bryostatin-1 exerts its effects on exhausted CD8+ T cells, we performed RNA-sequencing (RNA-seq) on in vitro exhausted OT- I CD8+ T cells which were treated with bryostatin-1 or DMSO, with single peptide stimulated cells as non-exhausted controls. Taken together, our study demonstrate bryostatin-1's effect on exhausted CD8+ T cells and bryostatin-1's potential in enhancing T cell immunity against chronic infection or cancer.
Project description:CD8 T cells normally differentiate from resting naïve T cells into function effector and then memory CD8 T cells following acute infections. During chronic viral infections, however, virus-specific CD8 T cells often become exhausted. We used microarrays to examine the gene expression differences between naive, effector, memory and exhausted virus-specific CD8 T cells following lymphocytic choriomeningitis virus infection. Experiment Overall Design: Three or four independent samples were sorted by flow cytometry for each cell type (naive, effector, memory and exhausted) virus-specific CD8 T cells. RNA was extracted and hybridized to Affymetrix microarrays.
Project description:Exhausted T cells express multiple co-inhibitory molecules that impair their function and limit immunity to chronic viral infection. Defining novel markers of exhaustion is important both for identifying and potentially reversing T cell exhaustion. Herein, we show that the ectonucleotidse CD39 is a marker of exhausted CD8+ T cells. CD8+ T cells specific for HCV or HIV express high levels of CD39, but those specific for EBV and CMV do not. CD39 expressed by CD8+ T cells in chronic infection is enzymatically active, co-expressed with PD-1, marks cells with a transcriptional signature of T cell exhaustion and correlates with viral load in HIV and HCV. In the mouse model of chronic Lymphocytic Choriomeningitis Virus infection, virus-specific CD8+ T cells contain a population of CD39high CD8+ T cells that is absent in functional memory cells elicited by acute infection. This CD39high CD8+ T cell population is enriched for cells with the phenotypic and functional profile of terminal exhaustion. These findings provide a new marker of T cell exhaustion, and implicate the purinergic pathway in the regulation of T cell exhaustion. CD8+ T cells from subjects with HCV infection were sorted and pelleted and re-suspended in TRIzol (Invitrogen). RNA extraction was performed using the RNAdvance Tissue Isolation kit (Agencourt). Concentrations of total RNA were determined with a Nanodrop spectrophotometer or Ribogreen RNA quantification kits (Molecular Probes/Invitrogen). RNA purity was determined by Bioanalyzer 2100 traces (Agilent Technologies). Total RNA was amplified with the WT-Ovation Pico RNA Amplification system (NuGEN) according to the manufacturer's instructions. After fragmentation and biotinylation, cDNA was hybridized to HG-U133A 2.0 microarrays (Affymetrix).
Project description:CTL exhaustion is driven by chronic antigen stimulation and is characterized by specific molecular, phenotypic and functional changes. Reversing CTLs exhaustion with immune checkpoint blockade (ICB) has provided clinical benefits in different types of cancer. However, the therapeutic effects of ICB varies among patients and cancer types. Ibrutinib, a potent BTK inhibitor, is reported that it improved T cell function in ibrutinib long-term treated chronic lymphocytic leukemia patients. However, the mechanism remains unclear. We hypothesized ibrutinib can directly act on CD8+ T cells and reinvigorates exhausted CTLs. To test this, we generated in vitro exhausted OT-I cells as previously described (Zhao M et al PLoS Pathog. 16(6): e1008555) by repeatedly stimulating cells with SIINFEKL peptide. We tested the effect of ibrutinib on inhibitory receptor, exhaustion-related transcription factor expression and cytokine (IFNγ, TNFα and IL-2) production. We found that ibrutinib decreased the expression of multiple inhibitory receptors on in vitro exhausted CTL while the critical transcription factor, Tox was downregulated. The cytokine production of exhausted cells was partially improved after ibrutinib treatment. Importantly, using btk deficient mice we found the effect of ibrutinib was independent of BTK expression. To conclude, these findings suggest that ibrutinib reduces CTL exhaustion. Our study provides evidence for ibrutinib’s synergistic use with cancer immunotherapy.
Project description:To investigate bryostain's effect on Raji , we performed a whole-transcriptome RNA sequencing experiment for Raji cells treated with Bryostatin and established differntial expression profile comparing to raji treated with DMSO.
Project description:Since exhausted CD8 T-cells are known to have a strong epigenetic imprint, which is a major obstacle for reinvigoration, we investigated whether the induced Klf4 expression could change the epigenetic status of the exhausted CD8 T-cells. For this, we performed ATAC-sequencing and compared chromatin landscapes between naïve, in vitro generated effector, exhausted (GFP-induced), and reinvigorated (KLF4-induced) CD8 T-cells.
Project description:TGFb signaling is a major pathway associated with poor clinical outcome in patients with
advanced metastatic cancers and non-response to immune checkpoint blockade, particularly in the immune-excluded tumor phenotype. While previous pre-clinical studies demonstrated that converting tumors from an excluded to an inflamed phenotype and curative anti-tumor immunity require attenuation of both PD-L1 and TGFb signaling, the underlying cellular mechanisms remain unclear. Recent studies suggest that stem cell-like CD8 T cells (TSCL) can differentiate into non-exhausted CD8 T effector cells that drive durable anti-tumor immunity. Here, we show that TGFb and PD-L1 restrain TSCL expansion as well as replacement of progenitor exhausted and dysfunctional CD8 T cells with non-exhausted IFNghi CD8 T effector cells in the tumor microenvironment (TME). Blockade of TGFb and PD-L1 generated IFNghi CD8 T effector cells with enhanced motility, enabling both their accumulation in the TME and increased interaction with other cell types. Ensuing IFNg signaling markedly transformed myeloid, stromal, and tumor niches to yield a broadly immune-supportive ecosystem. Blocking IFNg completely abolished the effect of anti-PD-L1/ TGFb combination therapy. Our data suggest that TGFb works in concert with PD-L1 to prevent TSCL expansion and replacement of exhausted CD8 T cells with fresh CD8
T effector cells, thereby maintaining the CD8 T cell compartment in a dysfunctional state.