Increased Programmed Death Ligand 1 Expression Research Articles

Association of pre-existing conditions with major driver mutations and PD-L1 expression in NSCLC

ObjectivesThis study aims to explore how pre-existing conditions such as blood types, family history of cancer and comorbid diseases correlate with the genetic and programmed death-ligand 1 (PD-L1) expression that...

Beta cell extracellular vesicle PD-L1 as a novel regulator of CD8+ T cell activity and biomarker during the evolution of type 1 diabetes.

Surviving beta cells in type 1 diabetes respond to inflammation by upregulating programmed death-ligand 1 (PD-L1) to engage immune cell programmed death protein 1 (PD-1) and limit destruction by self-reactive immune cells. Extracellular vesicles (EVs) and their cargo can serve as biomarkers of beta cell health and contribute to islet intercellular communication. We hypothesised that the inflammatory milieu of type 1 diabetes increases PD-L1 in beta cell EV cargo and that EV PD-L1 may protect beta cells against immune-mediated cell death. Beta cell lines and human islets were treated with proinflammatory cytokines to model the proinflammatory type 1 diabetes microenvironment. EVs were isolated using ultracentrifugation or size exclusion chromatography and analysed via immunoblot, flow cytometry and ELISA. EV PD-L1 binding to PD-1 was assessed using a competitive binding assay and in vitro functional assays testing the ability of EV PD-L1 to inhibit NOD CD8+ T cells. Plasma EV and soluble PD-L1 were assayed in the plasma of islet autoantibody-positive (Ab+) individuals or individuals with recent-onset type 1 diabetes and compared with levels in non-diabetic control individuals. PD-L1 protein co-localised with tetraspanin-associated proteins intracellularly and was detected on the surface of beta cell EVs. Treatment with IFN-α or IFN-γ for 24 h induced a twofold increase in EV PD-L1 cargo without a corresponding increase in the number of EVs. IFN exposure predominantly increased PD-L1 expression on the surface of beta cell EVs and beta cell EV PD-L1 showed a dose-dependent capacity to bind PD-1. Functional experiments demonstrated specific effects of beta cell EV PD-L1 to suppress proliferation and cytotoxicity of murine CD8+ T cells. Plasma EV PD-L1 levels were increased in Ab+individuals, particularly in those positive for a single autoantibody. Additionally, in Ab+ individuals or those who had type 1 diabetes, but not in control individuals, plasma EV PD-L1 positively correlated with circulating C-peptide, suggesting that higher EV PD-L1 could be protective for residual beta cell function. IFN exposure increases PD-L1 on the beta cell EV surface. Beta cell EV PD-L1 binds PD1 and inhibits CD8+ T cell proliferation and cytotoxicity. Circulating EV PD-L1 is higher in Ab+ individuals than in control individuals. Circulating EV PD-L1 levels correlate with residual C-peptide at different stages in type 1 diabetes progression. These findings suggest that EV PD-L1 could contribute to heterogeneity in type 1 diabetes progression and residual beta cell function and raise the possibility that EV PD-L1 could be exploited as a means to inhibit immune-mediated beta cell death.

Beta cell extracellular vesicle PD-L1 as a novel regulator of CD8+ T cell activity and biomarker during the evolution of Type 1 Diabetes.

Surviving beta cells in type 1 diabetes respond to inflammation by upregulating programmed death-ligand 1 (PD-L1) to engage immune cell programmed death-1 (PD-1) and limit destruction by self-reactive immune cells. Extracellular vesicles (EVs) and their cargo can serve as biomarkers of beta cell health and contribute to islet intercellular communication. We hypothesized that the inflammatory milieu of type 1 diabetes increases PD-L1 in beta cell EV cargo and that EV PD-L1 may protect beta cells against immune-mediated cell death. Beta cell lines and human islets were treated with proinflammatory cytokines to model the proinflammatory type 1 diabetes microenvironment. EVs were isolated using ultracentrifugation or size exclusion chromatography and analysed via immunoblot, flow cytometry, and ELISA. EV PD-L1: PD-1 binding was assessed using a competitive binding assay and in vitro functional assays testing the ability of EV PD-L1 to inhibit NOD CD8 T cells. Plasma EV and soluble PD-L1 were assayed in plasma of individuals with islet autoantibody positivity (Ab+) or recent-onset type 1 diabetes and compared to non-diabetic controls. PD-L1 protein colocalized with tetraspanin-associated proteins intracellularly and was detected on the surface of beta cell EVs. 24-h IFN-α or IFN-γ treatment induced a two-fold increase in EV PD-L1 cargo without a corresponding increase in number of EVs. IFN exposure predominantly increased PD-L1 expression on the surface of beta cell EVs and beta cell EV PD-L1 showed a dose-dependent capacity to bind PD-1. Functional experiments demonstrated specific effects of beta cell EV PD-L1 to suppress proliferation and cytotoxicity of murine CD8 T cells. Plasma EV PD-L1 levels were increased in islet Ab+ individuals, particularly in those with single Ab+, Additionally, in from individuals with either Ab+ or type 1 diabetes, but not in controls, plasma EV PD-L1 positively correlated with circulating C-peptide, suggesting that higher EV-PD-L1 could be protective for residual beta cell function. IFN exposure increases PD-L1 on the beta cell EV surface. Beta cell EV PD-L1 binds PD1 and inhibits CD8 T cell proliferation and cytotoxicity. Circulating EV PD-L1 is higher in islet autoantibody positive patients compared to controls. Circulating EV PD-L1 levels correlate with residual C-peptide at different stages in type 1 diabetes progression. These findings suggest that EV PD-L1 could contribute to heterogeneity in type 1 diabetes progression and residual beta cell function and raise the possibility that EV PD-L1 could be exploited as a means to inhibit immune-mediated beta cell death.

PD-L1 expression from surgically resected lung tumors predictive of early progression in patients previously treated with targeted therapy for initially unresectable non-small cell lung cancer.

Recent evidences showed that resection of lung tumor post-targeted therapy has shown progression-free survival (PFS) benefits in initially unresectable patients. The aim of this study is to evaluate pathologic findings of resected lung tumor samples in patients who have undergone prior epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitor (TKI) treatment, and also to assess the prognostic factors related to outcomes after resection. The deidentified data of non-small cell lung cancer (NSCLC) patients admitted to seven university hospitals affiliated with the Catholic University of Korea were obtained from the Clinical Data Warehouse (CDW) database. Among screened patients, 40 individuals who had previously undergone targeted therapies and later received surgical resection of a primary lung tumor were evaluated for the study. All 40 patients were diagnosed with adenocarcinoma. Of these, 36 with EGFR mutations received prior EGFR TKI treatment. Only one postoperative complication, atrial fibrillation, was observed. At the time of resection, 19 patients showed primary lung tumor size regressing or unchanged, while 21 patients showed primary lung tumor regrowth or new lesions being developed before the resection. The group with no programmed death-ligand 1 (PD-L1) expression from resected samples showed significantly better post-resection PFS when compared to the other group (P=0.01). In the Model II multivariate analysis for post-resection PFS, PD-L1 detection from the resected sample was significantly associated with PFS [P=0.03; hazard ratio (HR) =5.465; 95% confidence interval (CI): 1.200-24.885]. Furthermore, an increase in PD-L1 expression compared to the baseline value was associated with an increasing lung tumor burden at the time of resection (P=0.03). Resected specimen following targeted therapy can provide valuable clinical information that can be used to predict the prognosis of patients with initially unresectable NSCLC.

FAT10 induces immune suppression by upregulating PD-L1 expression in hepatocellular carcinoma.

The upregulation of programmed death ligand 1 (PD-L1) plays a crucial role in facilitating cancer cells to evade immune surveillance through immunosuppression. However, the precise regulatory mechanisms of PD-L1 in hepatocellular carcinoma (HCC) remain undefined. The correlation between PD-L1 and ubiquitin-like molecules (UBLs) was studied using sequencing data from 20 HCC patients in our center, combined with TCGA data. Specifically, the association between FAT10 and PD-L1 was further validated at both the protein and mRNA levels in HCC tissues from our center. Subsequently, the effect of FAT10 on tumor progression and immune suppression was examined through both in vivo and in vitro experiments. Utilizing sequencing data, qPCR, and Western blotting assays, we confirmed that FAT10 was highly expressed in HCC tissues and positively correlated with PD-L1 expression. Additionally, in vitro experiments demonstrated that the overexpression of FAT10 fostered the proliferation, migration, and invasion of HCC cells. Furthermore, the overexpression of FAT10 in HCC cells led to an increase in PD-L1 expression, resulting in the inhibition of T cell proliferation and the enhancement of HCC cell resistance to T cell-mediated cytotoxicity. Moreover, in vivo experiments utilizing the C57BL/6 mouse model revealed that overexpression of FAT10 effectively suppressed the infiltration of CD8 + GZMB + and CD8 + Ki67 + T cells, as well as reduced serum levels of TNF-α and IFN-γ. Mechanistically, we further identified that FAT10 upregulates PD-L1 expression via activating the PI3K/AKT/mTOR pathway, but not in a ubiquitin-like modification. In conclusion, our findings indicate that FAT10 promotes immune evasion of HCC via upregulating PD-L1 expression, suggesting its potential as a novel target to enhance the efficiency of immunotherapy in HCC.

Treg-derived TGF-β1 dampens cGAS-STING signaling to downregulate the expression of class I MHC complex in multiple myeloma

Multiple myeloma (MM) progression involves diminished tumor antigen presentation and an immunosuppressive microenvironment, characterized by diminished expression of major histocompatibility complexes (MHC) class I molecule and elevated programmed death ligand 1 (PDL1) in MM cells, along with an enriched population of regulatory T cells (Tregs). To investigate Treg's influence on MM cells, we established a co-culture system using Tregs from MM patients and the MM cell lines (MM.1S and SK-MM-1) in vitro and assessed the effects of intervening in the relevant pathways connecting Tregs and MM cells in vivo. In vitro, Tregs induced transforming growth factor beta-1 (TGF-β1) production, downregulated MHC I members, and increased PDL1 expression in MM cells. Treg-derived TGF-β1 suppressed the cGAS-STING pathway, contributing to the loss of MHC I molecule expression and PDL1 upregulation. Correspondingly, neutralizing TGF-β1 or activating the cGAS-STING pathway restored MHC I and PDL1 expression, effectively countering the pro-tumorigenic effect of Tregs on MM cells in vivo. These data elucidated how Tregs influence tumor antigen presentation and immunosuppressive signal in MM cells, potentially providing therapeutic strategies, such as neutralizing TGF-β1 or activating the cGAS-STING pathway, to address the immune escape and immunosuppressive dynamics in MM.

Transmural Flow Upregulates PD-L1 Expression in Microvascular Networks.

Endothelial programmed death-ligand 1 (PD-L1) expression is higher in tumors than in normal tissues. Also, tumoral vasculatures tend to be leakier than normal vessels leading to a higher trans-endothelial or transmural fluid flow. However, it is not clear whether such elevated transmural flow can control endothelial PD-L1 expression. Here, a new microfluidic device is developed to investigate the relationship between transmural flow and PD-L1 expression in microvascular networks (MVNs). After treating the MVNs with transmural flow for 24h, the expression of PD-L1 in endothelial cells is upregulated. Additionally, CD8 T cell activation by phytohemagglutinin (PHA) is suppressed when cultured in the MVNs pre-conditioned with transmural flow. Moreover, transmural flow is able to further increase PD-L1 expression in the vessels formed in the tumor microenvironment. Finally, by utilizing blocking antibodies and knock-out assays, it is found that transmural flow-driven PD-L1 upregulation is controlled by integrin αVβ3. Overall, this study provides a new biophysical explanation for high PD-L1 expression in tumoral vasculatures.

Adenosine increases PD-L1 expression in mesenchymal stromal cells derived from cervical cancer through its interaction with A2AR/A2BR and the production of TGF-β1.

Mesenchymal stromal cells (MSCs) together with malignant cells present in the tumor microenvironment (TME), participate in the suppression of the antitumor immune response through the production of immunosuppressive factors, such as transforming growth factor beta 1 (TGF-β1). In previous studies, we reported that adenosine (Ado), generated by the adenosinergic activity of cervical cancer (CeCa) cells, induces the production of TGF-β1 by interacting with A2AR/A2BR. In the present study, we provide evidence that Ado induces the production of TGF-β1 in MSCs derived from CeCa tumors (CeCa-MSCs) by interacting with both receptors and that TGF-β1 acts in an autocrine manner to induce the expression of programmed death ligand 1 (PD-L1) in CeCa-MSCs, resulting in an increase in their immunosuppressive capacity on activated CD8+ T lymphocytes. The addition of the antagonists ZM241385 and MRS1754, specific for A2AR and A2BR, respectively, or SB-505124, a selective TGF-β1 receptor inhibitor, in CeCa-MSC cultures significantly inhibited the expression of PD-L1. Compared with CeCa-MSCs, MSCs derived from normal cervical tissue (NCx-MSCs), used as a control and induced with Ado to express PD-L1, showed a lower response to TGF-β1 to increase PD-L1 expression. Those results strongly suggest the presence of a feedback mechanism among the adenosinergic pathway, the production of TGF-β1, and the induction of PD-L1 in CeCa-MSCs to suppress the antitumor response of CD8+ T lymphocytes. The findings of this study suggest that this pathway may have clinical importance as a therapeutic target.

FOXA1/UBE2T Inhibits CD8+T Cell Activity by Inducing Mediates Glycolysis in Lung Adenocarcinoma.

Immune escape is a key factor influencing survival rate of lung adenocarcinoma (LUAD) patients, but molecular mechanism of ubiquitin binding enzyme E2T (UBE2T) affecting immune escape of LUAD remains unclear. The objective was to probe role of UBE2T in LUAD. Bioinformatics means were adopted for analyzing UBE2T and forkhead box A1 (FOXA1) expression in LUAD tissues, the gene binding sites, the pathway UBE2T regulates, and the correlation between UBE2T and glycolysis genes. Dual luciferase and chromatin immunoprecipitation (ChIP) assays were conducted for validating the binding relationship between the two genes. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot were employed to evaluate UBE2T, FOXA1, and programmed death ligand 1 (PD-L1) levels in cancer cells. MTT assay was conducted for detecting cell viability. Cytotoxicity assay detected CD8+T cell toxicity. Cytokine expression was assayed by enzyme linked immunosorbent assay (ELISA). Extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) were assayed by extracellular flow analyzer. Glycolytic gene expression was analyzed by qRT-PCR, and glycolysis-related indicators were detected by ELISA. Immunohistochemistry (IHC) detected CD8+T cell infiltration in tumor tissues. FOXA1 and UBE2T were up-regulated in LUAD, and a binding site existed between UBE2T and FOXA1. Overexpressing UBE2T could increase PD-L1 expression and inhibit toxicity of CD8+T cells to LUAD cells. Overexpressing UBE2T repressed CD8+T cell activity in LUAD by activating the glycolysis pathway, and the addition of glycolysis inhibitor 2-deoxy-d-glucose (2-DG) reversed the above results. Mechanistically, FOXA1 promoted the immune escape of LUAD by up-regulating UBE2T and thus mediating glycolysis. In vivo experiments revealed that UBE2T knockdown hindered tumor growth, inhibited PD-L1 expression, and facilitated CD8+T cell infiltration. FOXA1 up-regulated the expression of UBE2T, which activated glycolysis, and thus inhibited activity of CD8+T cells, causing immune escape of LUAD.

PD-L1 Expression in High-Risk Non-Muscle-Invasive Bladder Cancer Is Influenced by Intravesical Bacillus Calmette-Guérin (BCG) Therapy.

In the expanding landscape of immune checkpoint inhibitors (CPI) in high-risk (HR) non-muscle-invasive bladder cancer (NMIBC), the role of programmed death ligand 1 (PD-L1) as prognostic and predictive is increasingly significant. However, data evaluating its variability and susceptibility to Bacillus Calmette-Guérin (BCG) therapy in HR NMIBC patients is scarce. This retrospective study analyzed 126 HR NMIBC tissue samples from 63 patients (38× BCG-treated, 25× BCG-naïve) at two time points to assess PD-L1 expression using the 'combined positivity score' (CPS) with the 22C3 DAKO antibody method and correlated it with clinicopathological parameters. A CPS > 10 defined PD-L1 positivity. The impact of initial PD-L1 status and its change over time on time-to-recurrence, progression-free survival, and overall survival (TTR, PFS, OS) was analyzed using Kaplan-Meier and Cox proportional hazard models. BCG treatment significantly increased PD-L1 expression (5.31 vs. 0.22, p = 0.0423), with PD-L1 positive cases rising post-treatment in the BCG group and remaining unchanged in BCG-naïve patients. Multivariate analysis including T-stage, CIS, grading, tumor size, multifocality, age, and sex revealed a significant correlation between PD-L1 status change to positivity and improved TTR (p = 0.03). Our findings demonstrate a potential modulation of the PD-L1 status by an intravesical BCG therapy. However, its prognostic value appears limited.

Adenosine Increases the Immunosuppressive Capacity of Cervical Cancer Cells by Increasing PD-L1 Expression and TGF-β Production through Its Interaction with A2AR/A2BR.

The present study provides evidence showing that adenosine (Ado) increases the expression of programmed death ligand 1 (PD-L1) in cervical cancer (CeCa) cells by interacting with A2AR/A2BR and that TGF-β1 acts in an autocrine manner to induce PD-L1 expression, enhancing the immunosuppressive effects of CeCa cells on activated T lymphocytes (ATLs) and CD8+ cytotoxic T lymphocytes (CTLs) specific for antigenic peptides derived from E6 and E7 proteins of HPV-16. Interestingly, the addition of the antagonists ZM241385 and MRS1754, which are specific for A2AR and A2BR, respectively, or SB-505124, which is a selective TGF-β1 receptor inhibitor, to CeCa cell cultures significantly inhibited PD-L1 expression. In addition, supernatants from CeCa cells that were treated with Ado (CeCa-Ado Sup) increased the expression of PD-1, TGF-β1, and IL-10 and decreased the expression of IFN-γ in ATLs. Interestingly, the addition of an anti-TGF-β neutralizing antibody strongly reversed the effect of CeCa-Ado Sup on PD-1 expression in ATLs. These results strongly suggest the presence of a feedback mechanism that involves the adenosinergic pathway, the production of TGF-β1, and the upregulation of PD-L1 expression in CeCa cells that suppresses the antitumor response of CTLs. The findings of this study suggest that this pathway may be clinically important and may be a therapeutic target.

Cyclin-dependent kinase inhibitors enhance programmed cell death protein 1 immune checkpoint blockade efficacy in triple-negative breast cancer by affecting the immune microenvironment.

Clinical studies on programmed death-ligand 1 (PD-L1) immune checkpoint inhibitors for treating triple-negative breast cancer (TNBC) have shown unsatisfactory efficacy due to low tumor-infiltrating lymphocyte (TIL) levels. Inhibitors targeting cyclin-dependent kinase (CDK) proteins can affect the immune microenvironment, increase TIL levels, and promote antitumor immunity, thus providing a new direction for TNBC treatment strategies. The authors tested three CDK inhibitors on the TNBC cell lines MDA-MB-231 and 4T1 and validated their antitumor effects and impact on the immune microenvironment using multiple detection methods. They verified the efficacy and immune-related mechanisms of different combination therapy experiments in a 4T1 cell-transplanted BALB/c mouse model. Treatment with CDK inhibitors for 72 hours inhibited cell proliferation, clone formation, migration, and cell-cycle arrest and induced apoptosis in human breast cancer MDA-MB-231 cells and mouse breast cancer 4T1 cells. CDK inhibitors suppressed DNA methylation by downregulating DNMT1, DNMT3a, and DNMT3b expression. These three inhibitors promoted the secretion of various chemokines, enhanced tumor cell antigen presentation, and increased PD-L1 expression. CDK inhibitors improved the efficacy of immunotherapy in animal models and increased TIL levels. Combination therapy with CDK and PD-L1 immune checkpoint inhibitors affects the immune microenvironment, promotes antitumor immunity, and improves the efficacy of immunotherapy for TNBC.

Impact of Increasing PD-L1 Levels on Outcomes to PD-1/PD-L1 Inhibition in Patients With NSCLC: A Pooled Analysis of 11 Prospective Clinical Trials.

Programmed death ligand 1 (PD-L1) expression is recognized as a key biomarker in the treatment of non-small cell lung cancer (NSCLC) with anti-PD(L)1 inhibitors. Previous work has highlighted that outcomes in patients with NSCLC treated with anti-PD(L)1 inhibitors generally improve with increasing PD-L1 expression. The objectives of these analyses are to quantitate the effect of PD-L1 expression on outcomes, to characterize the potentially nonlinear relationship between PD-L1 expression and outcomes, and to assess potential differences in these relationships across subgroups. We performed a retrospective, pooled analysis of 11 clinical trials submitted to the US FDA between 2015 and 2022 that included patients with advanced NSCLC treated with anti-programmed death 1 or anti-PD-L1 immune checkpoint inhibitor (ICI) monotherapy in the first-line (1L) or second-line (2L) treatment setting. The clinical outcomes explored were overall survival (OS), progression-free survival (PFS), and objective response rate (ORR). The primary analysis population included 3806 patients with advanced NSCLC, of which 2040 were treated in 1L and 1766 in 2L. For patients with a PD-L1 score of 100% in the 1L setting, the hazard ratio versus a patient with 1% PD-L1 was 0.55 (95% CI, 0.43 to 0.70) for OS and 0.50 (95% CI, 0.41 to 0.61) for PFS. For patients with a PD-L1 score of 100% in the 2L setting, the hazard ratio versus a patient with 0% PD-L1 was 0.55 (95% CI, 0.43 to 0.71) for OS and 0.51 (95% CI, 0.41 to 0.63) for PFS. Subgroup analyses suggested that this relationship may vary by subgroup, particularly by region. These analyses suggest PD-L1 expression has an appreciable impact on clinical outcomes for patients with NSCLC treated with ICI. As the impact of PD-L1 expression on outcomes may vary across regions, it is critical that future trials are multiregional and enroll a diverse patient population.

The role of programmed death receptor (PD-)1/PD-ligand (L)1 in periodontitis and cancer.

The programmed-death-ligand-1 (PD-L1) is an immune-modulating molecule that is constitutively expressed on various immune cells, different epithelial cells and a multitude of cancer cells. It is a costimulatory molecule that may impair T-cell mediated immune response. Ligation to the programmed-death-receptor (PD)-1, on activated T-cells and further triggering of the related signaling pathways can induce T-cells apoptosis or anergy. The upregulation of PD-L1 in various cancer types, including oral squamous cell carcinomas, was demonstrated and has been linked to immune escape of tumors and poor prognosis. A bidirectional relationship exists between the increased PD-L1 expression and periodontitis as well as the epithelial-mesenchymal transition (EMT), a process of interconversion of epithelial cells to mesenchymal cells that may induce immune escape of tumors. Interaction between exosomal PD-L1 and PD-1 on T-cells may cause immunosuppression by blocking the activation and proliferation of T-cells. The efficacy and importance of treatment with PD-1/PD-L1 checkpoint inhibitors and their prognostic influence on human cancers was demonstrated. Regarding PD-1/PD-L1 checkpoint inhibitors, resistances exist or may develop, basing on various factors. Further investigations of the underlying mechanisms will help to overcome the therapeutic limitations that result from resistances and to develop new strategies for the treatment of cancer.

IGFBP3 induces PD-L1 expression to promote glioblastoma immune evasion

BackgroundGlioblastoma (GBM) characterized by immune escape is the most malignant primary brain tumors, which has strong immunosuppressive effect. Programmed death ligand-1 (PD-L1) is a recognized immunosuppressive member on the surface of tumor cells, and plays a crucial role in immune evasion of tumors. Actually, little is known about the regulation of PD-L1 expression in GBM. Insulin-like growth factor binding protein 3 (IGFBP3) is upregulated in GBM and is related to poor patient prognosis. However, it remains unclear whether IGFBP3 plays a role in the regulation of PD-L1 expression in GBM.MethodsThe role of IGFBP3 in the glioma immune microenvironment was investigated using the CIBERSORT algorithm. The correlation between IGFBP3 and PD-L1 expression was analyzed using TCGA and CGGA databases. QRT-PCR, immunoblotting and RNA-seq were used to examine the regulatory effect of IGFBP3 on PD-L1 expression. Co-culture assay, cell counting kit (CCK-8), qRT-PCR, ELISA and flow cytometry were performed to explore the function of IGFBP3 in inducing immunosuppression. The biological role of IGFBP3 was verified using immunohistochemical, immunofluorescence and mice orthotopic tumor model.ResultsIn this study, we analyzed immune cells infiltration in gliomas and found that IGFBP3 may be associated with an immunosuppressive microenvironment. Then, by analyzing TCGA and CGGA databases, our results showed that IGFBP3 and PD-L1 expression were positively correlated in GBM patients, but not in LGG patients. In vitro experiments conducted on different GBM cell lines revealed that the overexpression of IGFBP3 led to an increase in PD-L1 expression, which was reversible upon knockdown IGFBP3. Mechanistically, IGFBP3 activated the JAK2/STAT3 signaling pathway, leading to an increase in PD-L1 expression. Additionally, co-culture experiments results showed IGFBP3 overexpression induced upregulation of PD-L1 expression promoted apoptosis in Jurkat cells, and this effect was blocked by IGFBP3 antibody and PDL-1 inhibitors. Importantly, in vivo experiments targeting IGFBP3 suppressed tumor growth and significantly prolonged the survival of mice.ConclusionsThis research demonstrated IGFBP3 is a novel regulator for PD-L1 expression in GBM, and identified a new mechanism by which IGFBP3 regulates immune evasion through PD-L1, suggesting that IGFBP3 may be a potential novel target for GBM therapy.

PD-1/PD-L1 governed cross-talk of exhausted CD8+ T and memory B cells in systemic lupus erythematosus

BackgroundIndeterminate readout of the quantitative interferon-γ release test (QFT) for Mycobacterium tuberculosis screening is a specific laboratory finding for systemic lupus erythematosus (SLE), which may be due to T-cell exhaustion...

Hypoxia-induced PD-L1 expression and modulation of muscle stem cell allograft rejection.

Stem cell therapy has shown immense promise in treating genetic disorders, particularly muscular diseases like Duchenne muscular dystrophy (DMD). This study investigates a novel method to enhance the viability of stem cell transplants in DMD by upregulating Programmed Death Ligand 1 (PD-L1) in muscle stem cells (MuSCs) through preconditioning with hypoxia and/or interferon-γ (IFN-γ) to mitigate T cell immune rejection. MuSCs were treated with 5% hypoxia for 72h and further treated with IFN-γ to enhance PD-L1 expression. Additionally, gain and loss experiments using a PD-L1 inhibitor (BMS-1) were conducted to investigate cellular expression profiles in vitro and cell transplantation outcomes in vivo. Our results showed significant upregulation of PD-L1 in MuSCs under hypoxia and IFN-γ conditions without affecting cellular proliferation and differentiation in vitro. In vivo, these preconditioned MuSCs led to decreased infiltration of CD4+ and CD8+ T cells in implanted limb muscles of mouse models. Blocking PD-L1 reduced graft survival in muscles treated with MuSCs. Conversely, increased PD-L1 expression and reduced T cell infiltration correlated with improved graft survival, as identified by pre-labeled LacZ + MuSCs following transplantation. This study provides evidence that hypoxia and IFN-γ preconditioning of MuSCs can significantly enhance the efficacy of cell therapy for DMD by mitigating immune rejection. Our strategic approach aimed to improve donor cell survival and function post-transplantation by modifying immune responses towards the donor cells.

Acidosis-mediated increase in IFN-γ-induced PD-L1 expression on cancer cells as an immune escape mechanism in solid tumors

Immune checkpoint inhibitors have revolutionized cancer therapy, yet the efficacy of these treatments is often limited by the heterogeneous and hypoxic tumor microenvironment (TME) of solid tumors. In the TME, programmed death-ligand 1 (PD-L1) expression on cancer cells is mainly regulated by Interferon-gamma (IFN-γ), which induces T cell exhaustion and enables tumor immune evasion. In this study, we demonstrate that acidosis, a common characteristic of solid tumors, significantly increases IFN-γ-induced PD-L1 expression on aggressive cancer cells, thus promoting immune escape. Using preclinical models, we found that acidosis enhances the genomic expression and phosphorylation of signal transducer and activator of transcription 1 (STAT1), and the translation of STAT1 mRNA by eukaryotic initiation factor 4F (elF4F), resulting in an increased PD-L1 expression. We observed this effect in murine and human anti-PD-L1-responsive tumor cell lines, but not in anti-PD-L1-nonresponsive tumor cell lines. In vivo studies fully validated our in vitro findings and revealed that neutralizing the acidic extracellular tumor pH by sodium bicarbonate treatment suppresses IFN-γ-induced PD-L1 expression and promotes immune cell infiltration in responsive tumors and thus reduces tumor growth. However, this effect was not observed in anti-PD-L1-nonresponsive tumors. In vivo experiments in tumor-bearing IFN-γ−/− mice validated the dependency on immune cell-derived IFN-γ for acidosis-mediated cancer cell PD-L1 induction and tumor immune escape. Thus, acidosis and IFN-γ-induced elevation of PD-L1 expression on cancer cells represent a previously unknown immune escape mechanism that may serve as a novel biomarker for anti-PD-L1/PD-1 treatment response. These findings have important implications for the development of new strategies to enhance the efficacy of immunotherapy in cancer patients.

Chromosome 9p Duplication Promotes T-Cell Exhaustion and Enhances Stem Cell Clonogenic Potential in JAK2-Mutant Myeloproliferative Neoplasms

Myeloproliferative Neoplasms (MPNs) are a diverse group of clonal hematopoietic disorders originating from a single hematopoietic stem cell, causing an excessive production of mature blood cells. Classic forms of MPNs include polycythemia vera, essential thrombocythemia, and myelofibrosis. The most common mutation is a gain-of-function point mutation in the JAK2 gene, known as JAK2V617F. This mutation leads to constant activation of the JAK-STAT signaling pathway, resulting in the overgrowth of MPN cells. Furthermore, the variant allele frequency (VAF) of JAK2V617F has a significant impact on the severity and phenotype of the disease. Alongside many described genetic mutations, cytogenetic abnormalities are commonly observed in MPNs, particularly involving chromosome 9. As the JAK2 gene is located on the short arm of this chromosome, we hypothesized that chromosome 9 copy number abnormalities might be a disease modifier in JAK2V617F-mutant MPN patients. To characterize the biological effects of chromosome 9 copy number abnormalities on JAK2-mutated MPN cells, we analyzed circulating CD34+ hematopoietic stem and progenitor cells (HSPCs) as well as monocytes and granulocytes from 32 MPN patients. Through Next Generation Sequencing, we categorized the patients into three main groups based on JAK2 mutation and copy number status: patients with two copies of the JAK2 gene with either heterozygous (VAF between 20% and 60%; n=10) or homozygous (VAF > 60% n=10) JAK2V617F mutation, or patients carrying mutant JAK2 and gene amplification (n=12). In-depth analysis of JAK2-amplified patients revealed that the amplification involved the entire chromosome 9p, thus including other gene loci like CD274, which encodes programmed death-ligand 1 (PD-L1). Further investigation of the order-of-events and clonal hierarchies through droplet digital PCR on CD34+ cell-derived colonies showed that most colonies of 9p-duplicated patients had three copies of JAK2, with 2 out of 3 alleles harboring the JAK2 mutation and that point mutations are frequently the initial pathogenic event in clonal evolution, followed by amplification of the JAK2-mutated allele. Functionally, CD34+ cells from +9p patients displayed high clonogenicity and gave rise to a greater number of primitive colonies (Colony Forming Unit-Granulocyte, Erythrocyte, Monocyte, Megakaryocyte, CFU-GEMM). As JAK2 hyperactivation had been previously reported to lead to increased PD-L1 expression, we further explored the functional significance of CD274 amplification in +9p patients. Our analysis showed increased PD-L1 messenger RNA and protein levels in +9p patient CD14+ monocytes compared to those from patients carrying only two copies of chromosome 9. Moreover, immunofluorescence analysis demonstrated significant re-localization of PD-L1 to the cytoplasmic membrane in monocytes from +9p patients, but not in JAK2V617F-homozygous patients (panel A). Increased levels of PD-L1, an immune checkpoint known to curb T cell activation, led us to analyze the T cell compartment, which resulted enriched in CD3+/CD8+/CD57-/PD-1+ exhausted T-cells in +9p patients compared to other MPN patients and healthy donors (panel B). In conclusion, our comprehensive characterization of the molecular interplay between JAK2V617F and chromosome 9 alterations, along with their immunological implications due to PD-L1 hyperactivation, fills a critical knowledge gap and provides valuable insights into the disease progression of 9p-MPNs. Further analysis is ongoing to explore the associations between 9p duplication and hematological parameters in 9p-MPN patients for a better understanding of the clinical implications of this genetic abnormality in MPNs.

Assessment of programmed cell death ligand- 1 (PD-L1) expression in oral potentially malignant disorders and oral squamous cell carcinoma - An immunohistochemical study

OSCC is multifactorial and is a multistep process. It may arise de-novo or may be preceded by oral potentially malignant disorders(OPMD). During malignant transformation certain molecular changes are evident at cellular level even in the absence of phenotypic changes in the tissue. With the recent advances in molecular understanding of cancers, immune checkpoint inhibitors have been recognized as perpetrators or supporters in the pathophysiology of various cancers. One of the main immunosuppressive pathways is the programmed death 1 (PD-1)/programmed death-ligand 1 (PD-L1) in which there is an interaction between T-cell PD-1 receptor and PD-L1 on cancer cells. Upregulation of PD-L1 is associated with disease progression.To assess and compare the PD-L1 expression in OPMD and OSCC.64 Paraffin embedded tissue sections of histopathologically diagnosed cases of 32 OSCC and 32 OPMD were immunohistochemically stained with PD-L1 & its membranous expression was evaluated. Descriptive statistical analysis was applied.Thus the study showed 100 % PD-L1 positive expression in OSCC and PD-L1 expression increased with increase in histopathological. In case of OPMD 93.74 % showed positive PD-L1 expression. We found PDL1 expression is significantly higher in OSCC (Mean= 4.59 ± 1.965) compared to OPMD (Mean= 2.03 ± 1.204).Assessment of PD-L1 expression in OPMD patients will help us to screen the subjects with or without risk of malignant transformation as increase in PD-L1 expression signifies the increased risk of malignant change.