Galectin-9 Facilitates Epstein-Barr Virus Latent Infection and Lymphomagenesis in Human B Cells.

The immune regulator galectin-9 (Gal-9) is commonly involved in the regulation of cell proliferation, but with various impacts depending on the cell type. Here, we revealed that Gal-9 expression was persistently increased in Epstein-Barr virus (EBV)-infected primary B cells from the stage of early infection to the stage of mature lymphoblastoid cell lines (LCLs). This sustained upregulation paralleled that of gene sets related to cell proliferation, such as oxidative phosphorylation, cell cycle activation, and DNA replication. Knocking down or blocking Gal-9 expression obstructed the establishment of latent infection and outgrowth of EBV-infected B cells, while exogenous Gal-9 protein promoted EBV acute and latent infection and outgrowth of EBV-infected B cells at the early infection stage. Mechanically, stimulator of interferon gene (STING) activation or signal transducer and activator of transcription 3 (STAT3) inhibition impeded the outgrowth of EBV-infected B cells and promotion of Gal-9-induced lymphoblastoid cell line (LCL) transformation. Accordingly, Gal-9 expression was upregulated by forced EBV nuclear antigen 1 (EBNA1) expression in 293T cells in vitro. Clinical data showed that Gal-9 expression in B-cell lymphomas (BCLs) correlated positively with EBNA1 and disease stage. Targeting Gal-9 slowed LCL tumor growth and metastasis in xenografted immunodeficient mice. These findings highlight an oncogenic role of Gal-9 in EBV-associated BCLs, indicating that Gal-9 boosts the transformation of EBV-infected B cells. IMPORTANCE The cross talk between Epstein-Barr virus (EBV) and the host cell transcriptome assumes important roles in the oncogenesis of EBV-associated malignancies. Here, we first observed that endogenous Gal-9 expression was persistently increased along with an overturned V-type change in antivirus signaling during the immortalization of EBV-transformed B cells. Upregulation of Gal-9 promoted the outgrowth and latent infection of EBV-infected B cells, which was linked to B-cell-origin tumors by suppressing STING signaling and subsequently promoting STAT3 phosphorylation. EBV nuclear antigen EBNA1 induced Gal-9 expression and formed a positive feedback loop with Gal-9 in EBV-infected B cells. Tumor Gal-9 levels were positively correlated with disease stage and EBNA1 expression in patients with B-cell lymphomas (BCLs). Targeting Gal-9 slowed the growth and metastases of LCL tumors in immunodeficient mice. Altogether, our findings indicate that Gal-9 is involved in the lymphomagenesis of EBV-positive BCLs through cross talk with EBNA1 and STING signals.

A phase II randomised controlled trial of adjuvant tumour-infiltrating lymphocytes for pretreatment Epstein-Barr virus DNA-selected high-risk nasopharyngeal carcinoma patients.

PURPOSE: The safety and objective clinical responses were observed in the phase I study using adjuvant autologous tumour-infiltrating lymphocytes (TILs) following concurrent chemoradiotherapy (CCRT) in nasopharyngeal carcinoma (NPC) patients. METHODS AND MATERIALS: One hundred fifty-six patients with stage III-IVb and pretreatment Epstein-Barr virus DNA levels of ≥4000 copies/ml were randomly assigned to receive CCRT combined with TIL infusion (n = 78) or CCRT alone (n = 78). All patients received CCRT and patients assigned to the TIL group received TIL infusion within 1 week after CCRT. The primary endpoint was investigator-assessed progression-free survival (PFS) at 3 years. RESULTS: After a median follow-up of 62.3 months, no significant difference was observed in the 3-year PFS rate between the CCRT plus TIL infusion group and CCRT alone group (75.6% versus 74.4%, hazard ratios, 1.08; 95% confidence intervals, 0.62-1.89). TIL infusion was safe without grade 3 or 4 adverse events and all the high-grade adverse effects were associated with myelosuppression caused by CCRT. Exploratory analysis showed that a potential survival benefit was observed with TILs in patients with lower levels of circulating CD8+TIM3+ cells, serum IL-8 or PD-L1. The infused TIL products in patients with favourable outcomes were associated with increased transcription of interferon-γ and a series of inflammatory related genes and a lower exhausted score. CONCLUSION: The primary objective of prolonging PFS with CCRT plus TILs in high-risk NPC patients was not met. These findings may provide evidence for the design of future trials investigating the combination of TILs plus immune checkpoint inhibitors based on CCRT in high-risk NPC patients. TRIAL REGISTRATION NUMBER: NCT02421640.

T cell-intrinsic STING signaling promotes regulatory T cell induction and immunosuppression by upregulating FOXP3 transcription in cervical cancer.

BACKGROUND: Stimulator of interferon genes (STING) is an innate immune sensor of cytoplasmic double-stranded DNA originating from microorganisms and host cells. The activation of cytosolic DNA-STING pathway in tumor microenvironments is usually linked to more robust adaptive immune responses to tumors, however the intracellular function of STING in regulatory T cells is largely unknown. In the present study, we aimed to explore the contribution of intracellular STING activation to regulatory T cell induction (iTreg) in cervical cancer (CC) microenvironments. METHODS: Blood samples and tumor specimens were obtained from patients with CC. The intratumoral STING, CCL22, CD8 and forkhead box P3 (FOXP3) expression levels were measured by immunohistochemistry. T cell-specific STING conditional knockout mice (CD4-Cre/STINGflox/flox, TKO) were generated, and syngeneic TC-1 tumor model were investigated. The differentiation and molecular regulatory pathway of human and murine iTreg under different treatments were investigated by ex vivo assays, immunoblotting and quantitative PCR. Tumor-associated exosomes (T-EXO) were isolated from CC cell lines and exosomal contents were identified by ELISA and Western blot analysis. The impact of T-EXO on T cell differentiation was tested in in vitro cell culture. RESULTS: Increased STING, CCL22 level, FOXP3+ cells but decreased CD8+ cells in tumor tissues predicted poor survival. Tumor-bearing CD4-Cre-STINGflox/flox (TKO) mice displayed slower tumor growth tendencies as well as fewer FOXP3+ cells but higher CD8+ cell proportion in tumor tissues than wild-type (WT) mice. Activating of STING signaling cooperated with T cell receptor, interleukin-2 receptor and transforming growth factor-beta (TGF-ß) signals to promote CD4+CD25highFOXP3+ iTreg differentiation from both human and murine CD4+-naïve T cells from WT and IFNAR-/- mice but not TKO or IRF3-/- mice in vitro. Ectopic STING, TBK1 or IRF3 expression promoted iTreg differentiation from human CD4+-naïve T cells. T cell-intrinsic STING activation induced FOXP3 transcription through TBK1-IRF3-mediated SMAD3 and STAT5 phosphorylation independent of interferon-ß. In CC, tumor-derived exosomes activated STING signaling in tumor-infiltrated T cells by exosomal TGF-ß, cyclic GMP-AMP synthase and 2'-3'-cGAMP, leading to iTreg expansion. CONCLUSIONS: These findings highlight a novel mechanism for iTreg expansion mediated by tumor-derived exosome-activated T cell-intrinsic STING signal, and provide a rationale for developing immunotherapeutic strategies targeting STING signal in CC.

Phase I study of adjuvant immunotherapy with autologous tumor-infiltrating lymphocytes in locally advanced cervical cancer.

BACKGROUNDAdoptive cell therapy (ACT) with tumor-infiltrating lymphocytes (TILs) has achieved remarkable clinical efficacy in metastatic cancers such as melanoma and cervical cancer (CC). Here, we explored the safety, feasibility, and preliminary tumor response and performed translational investigations of adjuvant immunotherapy using infusion of autogenous TILs (auto-TILs) following concurrent chemoradiotherapy (CCRT) in patients with CC who had locally advanced disease.METHODSTwenty-seven patients with CC with stage III-IV disease were recruited in this single-center, phase I study. TILs were isolated from lesions in the uterine cervix and generated under good manufacturing practice (GMP) conditions and then infused after CCRT plus i.m. IL-2 injections.RESULTSTILs from 20 of the 27 patients were successfully expanded, with a feasibility of 74.1%. Twelve patients received TILs following CCRT. Adverse events (AEs) were primarily attributable to CCRT. Only 1 (8.3%) patient experienced severe toxicity with a grade 3 hypersensitivity reaction after TIL infusion. No autoimmune AEs, such as pneumonitis, hepatitis, or myocarditis, occurred, and there were no treatment-related mortalities. Nine of 12 patients (75.0%) attained a complete response, with a disease control duration of 9-22 months. Translational investigation showed that the transcriptomic characteristics of the infused TIL products and some immune biomarkers in the tumor microenvironment and serum of patients with CC at baseline were correlated with the clinical response.CONCLUSIONTIL-based ACT following CCRT was safe in an academic center setting, with potentially effective responses in patients with locally advanced CC. "Hot" inflammatory immune environments were beneficial to the clinical efficacy of TIL-based ACT as adjuvant therapy.TRIAL REGISTRATIONClinicalTrials.gov NCT04443296.FUNDINGNational Key R&D Program; Sci-Tech Key Program of the Guangzhou City Science Foundation; the Guangdong Province Sci-Tech International Key Program; the National Natural Science Foundation of China.

Galectin-9 promotes a suppressive microenvironment in human cancer by enhancing STING degradation.

Galectin-9 (Gal-9) is known to enhance the expansion of myeloid-derived suppressor cells (MDSCs) in murine models. Its contribution to the expansion of MDSCs in human malignancies remain to be investigated. We here report that Gal-9 expression in nasopharyngeal carcinoma (NPC) cells enhances the generation of MDSCs (CD33+CD11b+HLA-DR-) from CD33+ bystander cells. The underlying mechanisms involve both the intracellular and secreted Gal-9. Inside carcinoma cells, Gal-9 up-regulates the expression of a variety of pro-inflammatory cytokines which are critical for MDSC differentiation, including IL-1ß and IL-6. This effect is mediated by accelerated STING protein degradation resulting from direct interaction of the Gal-9 carbohydrate recognition domain 1 with the STING C-terminus and subsequent enhancement of the E3 ubiquitin ligase TRIM29-mediated K48-linked ubiquitination of STING. Moreover, we showed that extracellular Gal-9 secreted by carcinoma cells can enter the myeloid cells and trigger the same signaling cascade. Consistently, high concentrations of tumor and plasma Gal-9 are associated with shortened survival of NPC patients. Our findings unearth that Gal-9 induces myeloid lineage-mediated immunosuppression in tumor microenvironments by suppressing STING signaling.