Nicotinamide Inhibits T Cell Exhaustion and Increases Differentiation of CD8 Effector T Cells

One of the limitations of immunotherapy is the development of a state referred to as T cell exhaustion (TEx) whereby T cells express inhibitory receptors (IRs) and lose production of effectors involved in killing of their targets. In the present studies we have used the repeated stimulation model with anti CD3 and anti CD28 to understand the factors involved in TEx development and treatments that may reduce changes of TEx. The results show that addition of nicotinamide (NAM) involved in energy supply to cells prevented the development of inhibitory receptors (IRs). This was particularly evident for the IRs CD39, TIM3, and to a lesser extent LAG3 and PD1 expression. NAM also prevented the inhibition of IL-2 and TNFα expression in TEx and induced differentiation of CD4+ and CD8 T cells to effector memory and terminal effector T cells. The present results showed that effects of NAM were linked to regulation of reactive oxygen species (ROS) consistent with previous studies implicating ROS in upregulation of TOX transcription factors that induce TEx. These effects of NAM in reducing changes of TEx and in increasing the differentiation of T cells to effector states appears to have important implications for the use of NAM supplements in immunotherapy against cancers and viral infections and require further exploration in vivo.

Increased Expression of TIGIT And KLRG1 Correlates With Impaired CD56Bright NK Cell Immunity In HPV16-Rrelated Cervical Intraepithelial Neoplasia

Background: The onset and progression of cervical intraepithelial neoplasia (CIN) are closely associated with the persistent infection of high-risk HPV (especially type16), which is mainly caused by immune escape. Natural killer (NK) cells play an important role against virally infected cells and tumor cells through a fine balance of signals from multiple surface receptors. Overexpression of non-MHC-I specific inhibitory receptors TIGIT, KLRG1, Siglec-7, LAIR-1, and CD300a on NK cells correlates with cellular exhaustion and immune evasion, but these receptors have not been investigated in CIN. The aim of the present study was to examine the potential role of NK cell non-MHC-I specific inhibitory receptors expression in immune escape from HPV16-related CIN patients .Methods: the subset distribution, IFN-γ and TNF-α expression levels and immunophenotype of TIGIT, KLRG1, Siglec-7, LAIR-1, and CD300a of NK cells were investigated in peripheral blood mononuclear cell samples by flow cytometry from 82 women, including HPV16(+) subjects with CIN 0, CIN I, and CIN II-III, and HPV subjects with CIN 0 (control). immunohistochemistry was applied to detect the expression of ligands for NK receptors in the cervical tissues. HPV types were identified by PCR assays.Results: The HPV16(+) subjects with high-grade lesions had an increased number of circulating peripheral blood CD56bright NK cells with reduced functionality and IFN-γ secretion. The expression levels of the inhibitory molecules TIGIT and KLRG1 on CD56bright NK cells increased in parallel with increasing CIN grade. In addition, TIGIT and KLRG1 related ligands, PVR, N-Cadherin and E-Cadherin expression level was also elevated with increasing CIN grade. Conclusions: Our results suggested that the reduced viability of CD56bright NK cells and increased TIGIT and KLRG1 expression represent an escape mechanism associated to persistent HPV16 infection and CIN progression. These results may facilitate the development of early-warning immune predictors and therapeutic strategies for HPV16-associated CIN based on the TIGIT and KLRG1 inhibitory pathways of NK cells.

Inhibitory pattern recognition receptors

Pathogen- and damage-associated molecular patterns are sensed by the immune system’s pattern recognition receptors (PRRs) upon contact with a microbe or damaged tissue. In situations such as contact with commensals or during physiological cell death, the immune system should not respond to these patterns. Hence, immune responses need to be context dependent, but it is not clear how context for molecular pattern recognition is provided. We discuss inhibitory receptors as potential counterparts to activating pattern recognition receptors. We propose a group of inhibitory pattern recognition receptors (iPRRs) that recognize endogenous and microbial patterns associated with danger, homeostasis, or both. We propose that recognition of molecular patterns by iPRRs provides context, helps mediate tolerance to microbes, and helps balance responses to danger signals.

Deciphering the Plasmodium falciparum malaria-specific CD4+ T cell response: ex vivo detection of high frequencies of PD-1+TIGIT+ EXP1-specific CD4+ T cells using a novel HLA-DR11-restricted MHC class II tetramer

Relatively little is known about the ex vivo frequency and phenotype of the P. falciparum-specific CD4+ T cell response in humans. The exported protein 1 (EXP1) is expressed by plasmodia at both, the liver stage and blood stage, of infection making it a potential target for CD4+ and CD8+ effector T cells. Here, a fluorochrome-labelled HLA-DRB1*11:01-restriced MHC class II tetramer derived from the P. falciparum EXP1 (aa62-74) was established for ex vivo tetramer analysis and magnetic bead enrichment in ten patients with acute malaria. EXP1-specific CD4+ T cells were detectable in nine out of ten (90%) malaria patients expressing the HLA-DRB1*11 molecule with an average ex vivo frequency of 0.11% (0-0.22%) of total CD4+ T cells. The phenotype of EXP1-specific CD4+ T cells was further assessed using co-staining with activation (CD38, HLA-DR, CD26), differentiation (CD45RO, CCR7, KLRG1, CD127), senescence (CD57) and co-inhibitory (PD-1, TIGIT, LAG-3, TIM-3) markers as well as the ectonucleotidases CD39 and CD73. EXP1-specific tetramer+ CD4+ T cells had a distinct phenotype compared to bulk CD4+ T cells and displayed a highly activated effector memory phenotype with elevated levels of co-inhibitory receptors and activation markers: EXP1-specific CD4+ T cells universally expressed the co-inhibitory receptors PD-1 and TIGIT as well as the activation marker CD38 and showed elevated frequencies of CD39. These results demonstrate that MHC class II tetramer enrichment is a sensitive approach to investigate ex vivo antigen-specific CD4+ T cells in malaria patients that will aid further analysis of the role of CD4+ T cells during malaria.

Selinexor Enhances NK Cell Activation Against Malignant B Cells via Downregulation of HLA-E

Selinexor is an FDA approved selective inhibitor of the nuclear export protein exportin-1 (XPO1) and causes specific cancer cell death via nuclear accumulation of tumor suppressor proteins. Design of rational studies for the use of selinexor in combination with other therapeutic agents, such as immunotherapies, requires a fundamental understanding of the effects of selinexor on the immune system. One important emerging area of immunotherapy are natural killer (NK) cell based therapeutics. NK cell function is tightly regulated by a balance of signals derived from multiple activating and inhibitory receptors. Thus in cancer, up-regulation of stress ligands recognised by activating receptors or down-regulation of HLA class I recognised by inhibitory receptors can result in an anti-cancer NK cell response. Changes in XPO1 function therefore have the potential to affect NK cell function through shifting this balance. We therefore sought to investigate how selinexor may affect NK cell function. Selinexor pre-treatment of lymphoma cells significantly increased NK cell mediated cytotoxicity against SU-DHL-4, JeKo-1 and Ramos cells, concurrent with increased CD107a and IFNγ expression on NK cells. In addition, selinexor enhanced ADCC against lymphoma cells coated with the anti-CD20 antibodies rituximab and obinutuzumab. In probing the likely mechanism, we identified that XPO1 inhibition significantly reduced the surface expression of HLA-E on lymphoma cell lines and on primary chronic lymphocytic leukemia cells. HLA-E binds the inhibitory receptor NKG2A and in accordance with this, selinexor selectively increased activation of NKG2A+ NK cells. Our data reveals that selinexor, in addition to its direct cytotoxic activity, also activates an anti-cancer immune response via disruption of the inhibitory NKG2A:HLA-E axis.

HO-1/BMMSC perfusion using a normothermic machine perfusion system reduces the acute rejection of DCD liver transplantation by regulating NKT cell co-inhibitory receptors in rats

Background Liver transplantation (LT) is required in many end-stage liver diseases. Donation after cardiac death (DCD) livers are often used, and treatment of acute rejection (ACR) requires the use of immunosuppressive drugs that are associated with complications. Bone marrow mesenchymal stem cells (BMMSCs) are used in treatment following LT; however, they have limitations, including low colonization in the liver. An optimized BMMSC application method is required to suppress ACR. Methods BMMSCs were isolated and modified with the heme oxygenase 1 (HO-1) gene. HO-1/BMMSCs were perfused into donor liver in vitro using a normothermic machine perfusion (NMP) system, followed by LT into rats. The severity of ACR was evaluated based on liver histopathology. Gene chip technology was used to detect differential gene expression, and flow cytometry to analyze changes in natural killer (NK) T cells. Results NMP induced BMMSCs to colonize the donor liver during in vitro preservation. The survival of HO-1/BMMSCs in liver grafts was significantly longer than that of unmodified BMMSCs. When the donor liver contained HO-1/BMMSCs, the local immunosuppressive effect was improved and prolonged, ACR was controlled, and survival time was significantly prolonged. The application of HO-1/BMMSCs reduced the number of NKT cells in liver grafts, increased the expression of NKT cell co-inhibitory receptors, and reduced NKT cell expression of interferon-γ. Conclusions NK cell and CD8+ T cell activation was inhibited by application of HO-1/BMMSCs, which reduced ACR of transplanted liver. This approach could be developed to enhance the success rate of LT.

EXTH-61. MODULATION OF THE IL-27 RECEPTOR SIGNALING PATHWAY IN GLIOBLASTOMA AND ONCOLYTIC VIROTHERAPY

Glioblastoma (GBM) is the most common primary malignant brain tumor in adults with median overall survival of 14-16 months. Glioblastoma progression involves multiple immunosuppressive pathways hindering the success of cancer immunotherapy. Oncolytic virotherapy is a promising approach to reprogram the glioblastoma microenvironment and restore anti-tumor immunity. Interleukin (IL)-27 receptor signaling pathway regulates development of effector T cells, IL-10 producing T regulatory type 1 (Tr1) cells and induction of co-inhibitory receptors associated with T cell exhaustion in cancer. In this study, we sought to tackle local and systemic GBM-induced immunosuppression using the novel rQNestin34.5v2 oncolytic herpes simplex virus type-1 (HSV-1), engineered to selectively replicate in glioma cells together with genetic disruptions of the IL-27 receptor signaling pathway. The antitumor activity of HSV-1 rQNestin34.5v2 was evaluated in IL-27ra-/- and wild-type C57BL/6 mice harboring orthotopic CT-2A and GL261 glioblastoma and in athymic nude mice harboring orthotopic patient derived glioblastoma xenografts (PDXs) selected from patients that had been treated in a clinical trial of intratumoral administration of HSV-1 rQNestin34.5v2 (ClinicalTrials.gov: NCT03152318). HSV-1 rQNestin34.5v2 exhibited superior capacity to infect glioma cells in vitro triggering release of proinflammatory cytokines and inducing immunogenic cell death in infected cells. Immune phenotyping of GL261 and CT-2A gliomas revealed astrocytes and microglia express the highest levels of IL-27R. Lack of IL-27R signaling decreased expression of the co-inhibitory receptors PD-1 and Tim-3 on circulating CD4+ T cells suggesting altered CD4+ T cell responses. In the tumor microenvironment, lack of IL-27R signaling decreased immune suppression as evidenced by reduced interleukin (IL)-10 secretion by glioma cells. Despite positive functional modifications on CD4+ T cells, global lack of IL-27R signaling promoted tumor growth accompanied by increased circulating myeloid derived suppressor cells (MDSCs) in the GL261 model. Experiments to address the immunoregulatory role of IL-27R signaling during HSV-1 rQNestin34.5v2 virotherapy-induced glioma tissue destruction are ongoing.

Single-Cell Transcriptomic Analysis of Ecosystems in Papillary Thyroid Carcinoma Progression

BackgroundDespite extensive research, the papillary thyroid carcinoma (PTC) ecosystem is poorly characterized and, in particular, locoregional progression. Available evidence supports that single-cell transcriptome sequencing (Sc-RNA seq) can dissect tumor ecosystems.MethodsTissue samples from one PTC patient, including matched primary tumor (Ca), lymph node (LN) metastasis, and paracancerous tissue (PCa), were subjected to Sc-RNA seq with 10×Genomics. Dual-label immunofluorescence and immunohistochemistry were used to confirm the existence of cell subtypes in a separate cohort.Results11,805 cell transcriptomes were profiled, cell landscapes of PTC were composed of malignant follicular epithelial cells (MFECs), CD8+ and CD4+ T cells, B cells, vascular endothelial cells, fibroblasts and cancer-associated fibroblasts (CAFs). Between Ca and LN ecosystems, the proportions of MFEC and interstitial cells were similar, less than 1/25(229/6,694, 361/3,895), while the proportion of normal follicular epithelial cells (NFECs) and interstitial cells was > 2 in PCa (455/171). NFECs in PCa formed a separate cluster, while MFECs in Ca and LN exhibited a profound transcriptional overlap, and the interstitial cells among these samples had an overall concordance in their identity and representation, albeit with some distinctions in terms of the cell percentage per subset. A fraction of the B cell subpopulation in Ca expressed inhibitory receptors, while their respective ligand genes were clearly transcribed in T cell and malignant epithelial cell clusters, while some CD8+ T cells in both Ca and LN produced high levels of inhibitory receptors whose respective ligands were overexpressed in some CD4+ T cells. Three CAF subtypes in Ca and LN were identified, which may be due to mutual transitions.ConclusionsOur data provide new insights into the PTC ecosystem and highlight the differences in ecosystems in PTC progression, which updates our understanding of PTC biology and will improve individualized patient treatment.