N-glycosylation reinforces interaction of immune checkpoint TIM-3 with a small molecule ligand

N-glycosylation of eukaryotic proteins plays roles in protein folding, trafficking, and signal transduction. The biological influence of the process is well understood, whereas the pharmacological impact of protein N-glycosylation is not well under discerned. The role of N-glycosylation on drug binding to protein has been rarely studied. We have modeled the influence of a bi-antennary N-glycan introduced at position N78 on the immune checkpoint TIM-3 (T cell immunoglobulin domain and mucin domain-containing molecule 3) on the interaction with a selective drug antagonist. The bulky N-glycan introduced at the consensus sequence Asn-Val-Thr has no influence on drug binding when the glycan adopts an extended conformation. But in a folded conformation, the glycan can interact directly with the triazoloquinazolinone derivative so as to further stabilize the drug-TIM-3 complex. The non-fucosylated glycan at position N78 markedly consolidates the drug interaction, via an additional H-bond interaction with the α3-mannose residue. It provides a gain of empirical potential energy of interaction (ΔE) of about 30 %. The presence of a more rigid fucosylated N-glycan is a little less favorable, with a gain of ΔE of about 20 %. The folded N-glycan appears to protect the ligand bound to the protein cavity, with the tricyclic core of the heterocyclic molecule sandwiched between two indole rings of tryptophan residues. Similar results were obtained when using a biantennary disialyl N-glycan with a bisecting GlcNAc residue and a tetra-antennary N-glycan. The molecular models illustrate the drug-stabilizing capacity of a bulky N-glycan positioned at a validated glycosylation site (N78 corresponding to N100 for the full-length protein). The modeling approach is useful to delineate further the role of the N-glycan of the immune checkpoint TIM-3 in interaction with small molecule ligands, and to guide the design of more potent compounds. The approach is transposable to other proteins to better comprehend the influence of N-glycans on drug-receptor interactions.

Radiotherapy combined with anti-CEACAM1 immunotherapy to induce survival advantage in glioma

BACKGROUND

We aimed to observe the effect of radiotherapy on the expression of immune checkpoint molecule CEACAM1 in patients with glioma and the therapeutical effect of radiotherapy combined with blockade of CEACAM1 in mice with intracranial gliomas.

METHODS

The expression of CEACAM1 on T-lymphocytes in the peripheral blood of patients with glioma was detected before and after radiotherapy; GL261 murine glioma cells (stably transfected with the luciferase gene) were implanted in the right caudate nucleus of C57BL/6 mice, and tumour growth was observed using the small animal in vivo imaging system. Mice were divided into 4 groups: (1) the isotype control; (2) the radiotherapy; (3) the anti-CEACAM1 treatment; and (4) the combination therapy. The survival of mice after treatment was recorded; the expression of CEACAM1 on murine glioma cells was detected by immunohistochemistry before and after radiotherapy; flow cytometry was adopted to detect CD8⁺ T-cells (Treg) (CD4⁺FoxP3⁺CD25⁺) among mouse brain-infiltrating T-cells; serum levels of IFN-γ and IL-10 were detected by ELISA; proliferation and apoptosis were observed by immunohistochemistry; Retrospective RNA-seq data analysis was conducted in a cohort of 325 patients with glioma in the Chinese Glioma Genome Atlas (CGGA) database and 702 patients in The Cancer Genome Atlas (TCGA) database.

RESULTS

The expression of CEACAM1 on CD4⁺ and CD8⁺ T-cells in the peripheral blood of patients with glioma was significantly higher 1 week after radiotherapy than before radiotherapy and was further increased 1 month after radiotherapy. Combined therapy notably inhibited the growth of intracranial tumours in mice and prolonged their survival time, with some mice being capable of surviving long-term (> 90 d). Immunohistochemistry revealed that the expression of CEACAM1 in murine glioma tissues after radiotherapy was elevated in a time-dependent manner. Flow cytometry analysis showed an increase in mouse brain-infiltrating CD8⁺ T-lymphocytes, a decrease in Treg cells, and an increase in CD8⁺ T/Treg cells after treatment. ELISA demonstrated the elevated levels of IFN and decreased levels of IL-10 in the serum of mice in the combination therapy group.

CONCLUSIONS

Radiotherapy combined with CEACAM1 inhibitors resulted in strong and durable anti-tumour immune responses against murine glioma and long-term survival of some mice. Hence, this study is expected to offer new effective immunotherapy strategies against glioma.

Microglial priming induced by loss of Mef2C contributes to postoperative cognitive dysfunction in aged mice

Postoperative cognitive dysfunction (POCD) is a common postoperative central nervous system (CNS) complication with a higher occurrence among aged individuals than among young individuals. The aim of this study was to explore the mechanisms by which POCD preferentially affects older individuals. We found here that exploratory laparotomy induced cognitive function decline in aged mice but not in young mice and that this decline was accompanied by inflammatory activation of microglia in the hippocampus. Furthermore, microglial depletion by feeding of a standard diet containing a colony stimulating factor 1 receptor (CSF1R) inhibitor (PLX5622) markedly protected aged mice from POCD. Notably, the expression of myocyte-specific enhancer 2C (Mef2C), an immune checkpoint that limits overactivation of microglia, was downregulated in aged microglia. Knocking down Mef2C induced a microglial priming phenotype in young mice, resulting in postoperative increases in the hippocampal levels of the inflammatory factors IL1-β, IL-6 and TNF-α that could impair cognition; these findings were consistent with the observations in aged mice. In vitro, BV2 cells lacking Mef2C released higher levels of inflammatory cytokines upon stimulation with lipopolysaccharide (LPS, a bacterial toxin) than Mef2C-sufficient cells. Moreover, upregulation of Mef2C in aged mice restrained postoperative microglial activation, attenuating the neuroinflammatory response and cognitive impairment. These results reveal that during aging, loss of Mef2C leads to microglial priming, amplifying postsurgical neuroinflammation and contributing to the vulnerability of elderly patients to POCD. Thus, targeting the immune checkpoint Mef2C in microglia may be a potential strategy for the prevention and treatment of POCD in aged individuals.

Peripheral HLA-G/ILT-2 immune checkpoint axis in acute and convalescent COVID-19 patients

The immunosuppressive non-classical human leukocyte antigen-G (HLA-G) can elicits pro-viral activities by down-modulating immune responses. We analysed soluble forms of HLA-G, IL-6 and IL-10 as well as on immune effector cell expression of HLA-G and its cognate ILT-2 receptor in peripheral blood obtained from hospitalised and convalescent COVID-19 patients. Compared with convalescents (N = 202), circulating soluble HLA-G levels (total and vesicular-bound molecules) were significantly increased in hospitalised patients (N = 93) irrespective of the disease severity. During COVID-19, IL-6 and IL-10 levels were also elevated. Regarding the immune checkpoint expression of HLA-G/ILT-2 on peripheral immune effector cells, the frequencies of membrane-bound HLA-G on CD3+ and CD14+ cells were almost identical in patients during and post COVID-19, while the frequency of ILT-2 receptor on CD3+ and CD14+ cells was increased during acute infection. A multi-parametric correlation analysis of soluble HLA-G forms with IL-6, IL-10, activation markers CD25 and CD154, HLA-G, and ILT-2 expression on immune cells revealed a strong positive correlation of soluble HLA-G forms with membrane-bound HLA-G molecules on CD3+/CD14+ cells only in convalescents. During COVID-19, only vesicular-bound HLA-G were positively correlated with the activation marker CD25 on T cells. Thus, our data suggest that the elevated levels of soluble HLA-G in COVID-19 are due to increased expression in organ tissues other than circulating immune effector cells. The concomitant increased expression of soluble HLA-G and ILT-2 receptor frequencies supports the concept that the immune checkpoint HLA-G/ILT-2 plays a role in the immune-pathogenesis of COVID-19.

Prognostic and immunotherapeutic predictive value of interleukin enhancer-binding factor 3 in hepatocellular carcinoma: Integrated bioinformatics and experimental analysis

Interleukin enhancer-binding factor 3 (ILF3) as an RNA-binding protein that plays a critical role in the process of cancer and antiviral responses. However, no researcher has focused on the pan-cancer analysis of ILF3, and the effect of ILF3 on tumor immunity is still largely unclear. This study synthetically analyzed the relationship between the expression of ILF3 across various cancers and prognosis, microsatellite instability (MSI), tumor mutational burden (TMB), tumor immune cell infiltration, and common immune checkpoint molecules by multiple bioinformatics databases. Experimentally, we detected the mRNA abundance of ILF3 and immune checkpoint molecules in liver hepatocellular carcinoma (LIHC) tissues. The functions of ILF3 on hepatocellular carcinoma (HCC) cells were verified by western blot assay and cytotoxicity assay. We found that ILF3 was aberrantly expressed and associated with the prognosis in several types of tumors. The ILF3 expression was significantly correlated with infiltrating levels of immune cells and immune molecules in certain cancers, particularly in LIHC. Detection of clinical liver cancer tissues confirmed the positive correlation between ILF3 and immune checkpoint molecules, including programmed cell death 1 (PD-1), programmed cell death ligand 1 (PD-L1), cytotoxic T lymphocyte-associated antigen 4 (CTLA4), lymphocyte-activation gene 3 (LAG3), and T cell immunoglobulin domain and mucin domain-3 (TIM3). Furthermore, reduced PD-L1 and increased sensitivity of HCC cells to T cells cytotoxicity were found in ILF3-knockdown cells. This work suggested ILF3 may be used as a prognostic marker for various tumors to predict the response to immunotherapy.

Novel extracellular role of REIC/Dkk-3 protein in PD-L1 regulation in cancer cells

The adenovirus-REIC/Dkk-3 expression vector (Ad-REIC) has been the focus of numerous clinical studies due to its potential for the quenching of cancers. The cancer-suppressing mechanisms of the REIC/DKK-3 gene depend on multiple pathways that exert both direct and indirect effects on cancers. The direct effect is triggered by REIC/Dkk-3-mediated ER stress that causes cancer-selective apoptosis, and the indirect effect can be classified in two ways: (i) induction, by Ad-REIC-mis-infected cancer-associated fibroblasts, of the production of IL-7, an important activator of T cells and NK cells, and (ii) promotion, by the secretory REIC/Dkk-3 protein, of dendritic cell polarization from monocytes. These unique features allow Ad-REIC to exert effective and selective cancer-preventative effects in the manner of an anticancer vaccine. However, the question of how the REIC/Dkk-3 protein leverages anticancer immunity has remained to be answered. We herein report a novel function of the extracellular REIC/Dkk-3-namely, regulation of an immune checkpoint via modulation of PD-L1 on the cancer-cell surface. First, we identified novel interactions of REIC/Dkk-3 with the membrane proteins C5aR, CXCR2, CXCR6, and CMTM6. These proteins all functioned to stabilize PD-L1 on the cell surface. Due to the dominant expression of CMTM6 among the proteins in cancer cells, we next focused on CMTM6 and observed that REIC/Dkk-3 competed with CMTM6 for PD-L1, thereby liberating PD-L1 from its complexation with CMTM6. The released PD-L1 immediately underwent endocytosis-mediated degradation. These results will enhance our understanding of not only the physiological nature of the extracellular REIC/Dkk-3 protein but also the Ad-REIC-mediated anticancer effects. KEY MESSAGES: • REIC/Dkk-3 protein effectively suppresses breast cancer progression through an acceleration of PD-L1 degradation. • PD-L1 stability on the cancer cell membrane is kept high by binding with mainly CMTM6. • Competitive binding of REIC/Dkk-3 protein with CMTM6 liberates PD-L1, leading to PD-L1 degradation.

Natural peptides for immunological regulation in cancer therapy: Mechanism, facts and perspectives

Cancer incidence and mortality rates are increasing annually. Treatment with surgery, chemotherapy and radiation therapy (RT) is unsatisfactory because many patients have advanced disease at the initial diagnosis. However, the emergence of immunotherapy promises to be an effective strategy to improve the outcome of advanced tumors. Immune checkpoint antibodies, which are at the forefront of immunotherapy, have had significant success but still leave some cancer patients without benefit. For more cancer patients to benefit from immunotherapy, it is necessary to find new drugs and combination therapeutic strategies to improve the outcome of advanced cancer patients and achieve long-term tumor control or even eradication. Peptides are promising choices for tumor immunotherapy drugs because they have the advantages of low production cost, high sequence selectivity, high tissue permeability, low toxicity and low immunogenicity etc., and the adjuvant matching and technologies like nanotechnology can further optimize the effects of peptides. In this review, we present the current status and mechanisms of research on peptides targeting multiple immune cells (T cells, natural killer (NK) cells, dendritic cells (DCs), tumor-associated macrophages (TAMs), regulatory T cells (Tregs)) and immune checkpoints in tumor immunotherapy; and we summarize the current status of research on peptide-based tumor immunotherapy in combination with other therapies including RT, chemotherapy, surgery, targeted therapy, cytokine therapy, adoptive cell therapy (ACT) and cancer vaccines. Finally, we discuss the current status of peptide applications in mRNA vaccine delivery.

Suicide in bipolar disorder patients is associated with hippocampal microglia activation and reduction of lymphocytes-activation gene 3 (LAG3) microglial checkpoint expression

BACKGROUND

Bipolar disorder (BD) is associated with marked functional impairments along with increased rate of suicide. Although there is ample evidence for the involvement of inflammatory processes and microglia activation in the pathophysiology of BD, the mechanisms that regulate these cells in BD patients, and particularly the role of microglia checkpoints, is still unclear.

METHODS

Immunohistochemical analyses of hippocampal sections from post-mortem brains of 15 BD patients and 12 control subjects were used to assess microglia density, by staining the microglia-specific receptor P2RY12, and microglia activation, by staining the activation marker MHC II. Given recent findings on the involvement of LAG3, which interacts with MHC II and serves as a negative microglia checkpoint, in depression and electroconvulsive therapy, we assessed the levels of LAG3 expression and their correlations with microglia density and activation.

RESULTS

There were no overall differences between BD patients and controls, but BD patients who committed suicide (N = 9) displayed a significant elevation in the overall microglia density and the density of MHC II-labeled microglia (but not other MHC II-labeled cells), compared with no suicide BD patients (N = 6) and controls. Furthermore, the percent of microglia expressing LAG3 was significantly reduced only in suicidal BD patients, with significant negative correlations between microglial LAG3 expression levels and the density of microglia, in general, and activated microglia, in particular.

CONCLUSION

Suicidal BD patients exhibit microglia activation, which is possibly mediated by reduced LAG3 checkpoint expression, suggesting that anti-microglial therapeutics, including LAG3 modulators, may be beneficial for this subgroup of patients.

Silencing tumor-intrinsic HHLA2 potentiates the anti-tumoral effect of paclitaxel on MG63 cells: Another side of immune checkpoint

BACKGROUND

Osteosarcoma is common type of bone cancer; however, the prognosis of patients with metastatic osteosarcoma is poor. As a new inhibitory immune checkpoint molecule, HHLA2 is upregulated in osteosarcoma. Herein, we studied the significance of tumor-intrinsic HHLA2 in MG-63 growth. Also, we examined the influence of combined therapy of HHLA2 knockdown with paclitaxel on the apoptosis, cell cycle, migration, and stemness of MG-63 cells.

METHODS

The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was performed to study the half-maximal inhibitory concentration (IC50) of paclitaxel and the cytotoxicity of HHLA2-small interfering RNA (siRNA) on MG-63 cells. The apoptosis and cell cycle were analyzed using flow cytometry. The wound-healing and colony formation assays were conducted to investigate the effect of paclitaxel and HHLA2 knockdown on the migration and stemness of MG-63 cells, respectively. QRT-PCR was used to determine the Bax, caspase-3, and Bcl-2 mRNA expression levels.

RESULTS

HHLA2 silencing has enhanced the chemosensitivity of MG-63 cells to paclitaxel. Besides, HHLA2 knockdown has increased the paclitaxel-induced cytotoxic effect on MG-63 cells. In terms of stimulating apoptosis, decreasing clonogenicity, halting the cell cycle at the sub G1 phase, and inhibiting migration, tumor-intrinsic HHLA2 silencing has increased these anti-tumor effects of paclitaxel on MG-63 cells. Besides, HHLA2 knockdown has potentiated paclitaxel-mediated Bcl-2 downregulation and paclitaxel-mediated caspase-3 and Bax upregulation in MG-63 cells.

CONCLUSION

Tumor-intrinsic HHLA2 knockdown increases the anti-tumoral effect of paclitaxel on MG-63 cells and enhances the chemosensitivity of MG-63 cells to paclitaxel.

Immune checkpoint inhibitors and reproductive failures

The human conceptus is a semi-allograft, which is antigenically foreign to the mother. Hence, the implantation process needs mechanisms to prevent allograft rejection during successful pregnancy. Immune checkpoints are a group of inhibitory pathways expressed on the surface of various immune cells in the form of ligand receptors. Immune cells possess these pathways to regulate the magnitude of immune responses and induce maternal-fetal tolerance. Briefly, 1) CTLA-4 can weaken T cell receptor (TCR) signals and inhibit T cell response; 2) The PD-1/PD-L1 pathway can reduce T cell proliferation, enhance T cell anergy and fatigue, reduce cytokine production, and increase T regulatory cell activity to complete the immunosuppression; 3) TIM3 interacts with T cells by binding Gal-9, weakening Th1 cell-mediated immunity and T cell apoptosis; 4) The LAG-3 binding to MHC II can inhibit T cell activation by interfering with the binding of CD4 to MHC II, and; 5) TIGIT can release inhibitory signals to NK and T cells through the ITIM structure of its cytoplasmic tail. Therefore, dysregulated immune checkpoints or the application of immune checkpoint inhibitors may impair human reproduction. This review intends to deliver a comprehensive overview of immune checkpoints in pregnancy, including CTLA-4, PD-1/PD-L1, TIM-3, LAG-3, TIGIT, and their inhibitors, reviewing their roles in normal and pathological human pregnancies.

PD-1/PD-L1 pathway: A double-edged sword in periodontitis

Periodontitis is a disease caused by infection and immunological imbalance, which often leads to the destruction of periodontal tissue. Programmed death protein 1 (PD-1) and its ligand: programmed death ligand 1 (PD-L1) are important "immune checkpoint" proteins that have a negative regulatory effect on T cells and are targets of immunotherapy. Studies have shown that the expression of PD-1 and PD-L1 in patients with periodontitis is higher than that in healthy individuals. The keystone pathogen Porphyromonas gingivalis (P. gingivalis) is believed to be the main factor driving the upregulation of PD-1/PD-L1. High expression of PD-1/PD-L1 can inhibit the inflammatory response and reduce the destruction of periodontal supporting tissues, but conversely, it can promote the "immune escape" of P. gingivalis, thus magnifying infections. In addition, the PD-1/PD-L1 pathway is also associated with various diseases, such as cancer and Alzheimer's disease. In this review, we discuss the influence and mechanism of the PD-1/PD-L1 pathway as a "double-edged sword" affecting the occurrence and development of periodontitis, as well as its function in periodontitis-related systemic disorders. The PD-1/PD-L1 pathway could be a new avenue for periodontal and its related systemic disorders therapy.

Wilms Tumor 1-Associated Protein Expression Is Linked to a T-Cell-Inflamed Phenotype in Pancreatic Cancer

BACKGROUND

The molecular driving forces of anti-tumor immunity in pancreatic ductal adenocarcinoma (PDAC) remain unclear, which causing great difficulty in identifying an appropriate treatment strategy.

AIMS

This study aims to explore the associations between expression of Wilms tumor 1-associated protein (WTAP) and effector T-cell infiltration in PDAC.

METHODS

In this study, we explored the association between WTAP expression and infiltration level of CD8+ T cells in PDAC. 178 PDAC samples were selected from The Cancer Genome Atlas (TCGA) database. The associations between diverse immune-cell infiltration, Tumor Mutation Burden (TMB), immune checkpoints, and WTAP expression were performed via R software. Transcriptional hallmarks of anti-tumor immunity and known T-cell-inflamed signature of PDAC were both selected to explore the relevance to WTAP expression. Potential immune checkpoint blockade (ICB) response to different WTAP expression was predicted with tumor immune dysfunction and exclusion (TIDE) algorithm.

RESULTS

WTAP was closely linked to CD8+ T-cell infiltration (r ≥ 0.5, P value < 0.05) and did not show notable association with TMB in PDAC. WTAP positively linked to T-cell-inflamed gene expression profiles (GEP) (IL2RB, IL2RA, ZAP70, ITK, CD3E, CD38, CD27, CD276, CD8A, CMKLR1, CXCR6, HLA-DQA1, HLA-DRB1, HLA-E, NKG7, and STAT1), cytolytic activity (GZMA and PRF1), various immune checkpoints (IDO1, CD274, HAVCR2, PDCD1, CTLA4, LAG3, and PDCD1LG2) and 4-chemokine signature (CCL4, CCL5, CXCL9, and CXCL10). Besides, increased expression of WTAP was related to a higher TIDE score.

CONCLUSIONS

WTAP marks PDAC tumors with an active anti-tumor phenotype and might help the identification of PDAC patients who might benefit from immunotherapies.

Soluble TIM-3 as a biomarker of progression and therapeutic response in cancers and other of human diseases

Immune checkpoints inhibition is a privileged approach to combat cancers and other human diseases. The TIM-3 (T cell immunoglobulin and mucin-domain containing-3) inhibitory checkpoint expressed on different types of immune cells is actively investigated as an anticancer target, with a dozen of monoclonal antibodies in (pre)clinical development. A soluble form sTIM-3 can be found in the plasma of patients with cancer and other diseases. This active circulating protein originates from the proteolytic cleavage by two ADAM metalloproteases of the membrane receptor shared by tumor and non-tumor cells, and extracellular vesicles. In most cancers but not all, overexpression of mTIM-3 at the cell surface leads to high level of sTIM-3. Similarly, elevated levels of sTIM-3 have been reported in chronic autoimmune diseases, inflammatory gastro-intestinal diseases, certain viral and parasitic diseases, but also in cases of organ transplantation and in pregnancy-related pathologies. We have analyzed the origin of sTIM-3, its methods of dosage in blood or plasma, its presence in multiple diseases and its potential role as a biomarker to follow disease progression and/or the treatment response. In contrast to sPD-L1 generated by different classes of proteases and by alternative splicing, sTIM-3 is uniquely produced upon ADAM-dependent shedding, providing a more homogenous molecular entity and a possibly more reliable molecular marker. However, the biological functionality of sTIM-3 remains insufficiently characterized. The review shed light on pathologies associated with an altered expression of sTIM-3 in human plasma and the possibility to use sTIM-3 as a diagnostic or therapeutic marker.

Comprehensive analysis of the role of ICOS ( CD278 ) in pan-cancer prognosis and immunotherapy

BACKGROUND

The immunological checkpoint known as Inducible T Cell Costimulatory Factor (ICOS, Cluster of Differentiation, CD278) is activated and expressed on T cells. Both somatic cells and antigen-presenting cells expressed its ligand, ICOSL (including tumor cells in the tumor microenvironment).It is important for immunosuppression. Uncertainty surrounds the function of ICOS in tumor immunity.

METHODS

Several bioinformatics techniques were employed by us to thoroughly examine the expression and prognostic value of ICOS in 33 cancers based on data collected from TCGA and GTEx. In addition, ICOS was explored with pathological stage, tumor-infiltrating cells, immune checkpoint genes, mismatch repair (MMR) genes, DNA methyltransferases (DNMTs), microsatellite instability (MSI),and tumor mutation burden (TMB).In addition,To ascertain the level of ICOS expression in various cells, qRT-PCR was employed.

RESULTS

The findings revealed that ICOS expression was up regulation in most cancer types. The high expression of ICOS in tumor samples was related to the poor prognosis of UVM and LGG; The positive prognosis was boosted by the strong expression of ICOS in OV, SARC, SKCM, THYM, UCEC, and HNSC. The result is that the expression of malignancy was revealed by the immune cells' invasion.profile of ICOS in different types of cancer. Different ways that ICOS expression is connected to immune cell infiltration account for variations in patient survival. Additionally, the TMB, MSI, MMR, and DNMT genes as well as ICOS expression are linked in many cancer types.The results of PCR showed that it is highly expressed in gastric, breast, liver and renal cell carcinoma cell lines compared with normal cells.

CONCLUSION

This study suggests that ICOS may be a potential tumor immunotherapy target and prognostic marker.

Targeting RNA N6-methyladenosine to synergize with immune checkpoint therapy

Cancer immunotherapy, especially immune checkpoint therapy, has revolutionized therapeutic options by reactivating the host immune system. However, the efficacy varies, and only a small portion of patients develop sustained antitumor responses. Hence, illustrating novel strategies that improve the clinical outcome of immune checkpoint therapy is urgently needed. N6-methyladenosine (m⁶A) has been proved to be an efficient and dynamic posttranscriptional modification process. It is involved in numerous RNA processing, such as splicing, trafficking, translation and degradation. Compelling evidence emphasizes the paramount role of m⁶A modification in the regulation of immune response. These findings may provide a foundation for the rational combination of targeting m⁶A modification and immune checkpoints in cancer treatment. In the present review, we summarize the current landscape of m⁶A modification in RNA biology, and highlight the latest findings on the complex mechanisms by which m⁶A modification governs immune checkpoint molecules. Furthermore, given the critical role of m⁶A modification in antitumor immunity, we discuss the clinical significance of targeting m⁶A modification to improve the efficacy of immune checkpoint therapy for cancer control.

Role of soluble forms of follicular helper T-cell membrane molecules in the pathogenesis of myasthenia gravis

This study examined the role of Tfh and Treg associated molecules also known as checkpoint molecules, their ligands, and IL-21 in myasthenia gravis (MG) pathogenesis. Serum levels of sPD-1, sPD-L1, sICOS, sICOSLG, sCTLA4, and IL-21 were measured in 39 patients with acetylcholine receptor (AChR) antibody-positive generalized MG and 27 controls. sPD-1 and IL-21 levels were higher in MG patients than in controls. Additionally, sPD-1 levels correlated positively with the levels of IL-21, sICOSLG, sCTLA4, and AChR antibody titers. sICOS are correlated with MGADL and AChR antibody titers. These Tfh associated molecules could be used as biomarkers of MG disease activity.

Adoptive cellular immunotherapy for solid neoplasms beyond CAR-T

In recent decades, immune checkpoint blockade and chimeric antigen receptor T cell (CAR-T) therapy are two milestone achievements in clinical immunotherapy. However, both show limited efficacies in most solid neoplasms, which necessitates the exploration of new immunotherapeutic modalities. The failure of CAR-T and immune checkpoint blockade in several solid neoplasms is attributed to multiple factors, including low antigenicity of tumor cells, low infiltration of effector T cells, and diverse mechanisms of immunosuppression in the tumor microenvironment. New adoptive cell therapies have been attempted for solid neoplasms, including TCR-T, CAR-natural killer cells (CAR-NK), and CAR-macrophages (CAR-M). Compared to CAR-T, these new adoptive cell therapies have certain advantages in treating solid neoplasms. In this review, we summarized the 40-year evolution of adoptive cell therapies, then focused on the advances of TCR-T, CAR-NK, and CAR-M in solid neoplasms and discussed their potential clinical applications.

Discovery of small-molecule PD-1/PD-L1 antagonists through combined virtual screening and experimental validation

Inhibition of the interaction between the PD-1 protein on activated lymphocytes and the PD-L1 protein on tumors represents a novel therapeutic approach for selective activation of the innate immune response against a variety of cancers. Therefore, the present study utilized a combined virtual and experimental screening approach to screen databases of both lead-like and larger molecules for identification of novel inhibitors of PD-1/PD-L1 interaction. First, high-throughput virtual screening of ∼3.7 million lead-like molecules using a rigid-receptor docking approach against both human PD-1 and PD-L1 proteins revealed possible small-molecule tractability of PD-1, but not PD-L1, binding interface. The subsequent work, therefore, involved screening of the National Cancer Institute (NCI) compound database against the PD-1 pocket. Several NCI compounds were identified with potential to bind to the PD-1 pocket and in turn inhibit the PD-1/PD-L1 interaction. The dynamic binding behavior of these molecules was further investigated using long 100 ns molecular dynamics (MD) stimulation revealing NSC631535 to be a potentially stable binder at PD-1 interface pocket. In support of these MD data, the experimental testing of NSC631535 exhibited 50% inhibition at ∼15 μM test concentration. The observed activity of this compound is promising as despite its relatively low molecular weight (415.5 g/mol) it is still capable of inhibiting the PD-1/PD-L1 interaction having a large interface area (∼1970 Å²). In summary, our integrated computational and experimental screening led to identification of a novel PD-1 antagonist that may serve as a starting point for further optimization into more potent small-molecule PD-1/PD-L1 inhibitors for cancer immunotherapy.

Contribution of the TIM-3/Gal-9 immune checkpoint to tropical parasitic diseases

Neglected tropical parasitic diseases (NTD) are prevalent in many countries and cost-effective treatments remain urgently needed. Novel approaches have been proposed to address these diseases through an action on immune co-inhibitory checkpoints which are exploited by parasites to evade the immune system. Among these checkpoints, TIM-3 has been shown to play a key role in antiparasitic immunity via a repression and functional attenuation of CD4⁺ and/or CD8⁺ T-cells. The present review discusses the role of the TIM-3/galectin-9 checkpoint in seven major NTD: Chagas disease, leishmaniasis and malaria (3 trypanosomatid infections), schistosomiasis, toxoplasmosis, echinococcosis and filariasis (4 helminth infections). In each case, the role of the checkpoint has been analyzed and the use of anti-TIM-3 antibodies evaluated as a potential therapeutic approach. In general, the parasitic infection is coupled with an upregulation of TIM-3 expressed on T cells, but not necessarily with an exhaustion of those T cells. In several cases, the use of anti-TIM-3 antibodies represent a possible strategy to reinforce the clearance and to reduce the parasite load. Promising data have been reported in cases of leishmaniasis, malaria and schistosomiasis, whereas a similar approach proved much less efficient (if not deleterious) in cases of echinococcosis and the Chagas disease. Nevertheless, the TIM-3 checkpoint warrants further consideration as a potential immune target to combat these pathologies, using antibodies or drugs capable of reducing directly or indirectly the expression and function of the checkpoint, to restore an immune control.

The biology of VSIG4: Implications for the treatment of immune-mediated inflammatory diseases and cancer

V-set and immunoglobulin domain containing 4 (VSIG4), a type I transmembrane receptor exclusively expressed in a subset of tissue-resident macrophages, plays a pivotal role in clearing C3-opsonized pathogens and their byproducts from the circulation. VSIG4 maintains immune homeostasis by suppressing the activation of complement pathways or T cells and inducing regulatory T-cell differentiation, thereby inhibiting the development of immune-mediated inflammatory diseases but enhancing cancer progression. Consequently, VSIG4 exhibits a potential therapeutic effect for immune-mediated inflammatory diseases, but also is regarded as a novel target of immune checkpoint inhibition in cancer therapy. Recently, soluble VSIG4, the extracellular domain of VSIG4, shed from the surface of macrophages, has been found to be a biomarker to define macrophage activation-related diseases. This review mainly summarizes recent new findings of VSIG4 in macrophage phagocytosis and immune homeostasis, and discusses its potential diagnostic and therapeutic usage in infection, inflammation, and cancer.

Construction and characterization of a cuproptosis- and immune checkpoint-based LncRNAs signature for breast cancer risk stratification

BACKGROUND

Cuproptosis is the most recently identified form of cell death, and copper homeostasis is an important cancer therapeutic target. However, the therapeutic benefits of cuproptosis-targeted treatment in BRCA remain undetermined. This study utilized LncRNAs linked to cuproptosis genes and immune checkpoint genes to generate a BRCA predictive signature.

METHODS

We screened a population of LncRNAs that correlated with both cuproptosis genes and immune checkpoint genes and used ten of these LncRNAs to construct a prognosis-predictive signature. We then validated and proved the efficacy of the signature in predicting the prognosis of BRCA patients. We also unraveled the relationship between the signature and the immunological milieu, immune function, and susceptibility to chemotherapy.

RESULTS

The signature derived from the ten cuproptosis- and immune-related prognostic LncRNAs (CuImP-LncRNAs) can be implied to categorize patients into two groups, including the high- and low-risk groups. The value of the signature was validated, and the risk score was verified as an independent prognostic indicator. The TIME and TMB distribution patterns and chemosensitivity were depicted in the high- and low-risk groups, respectively. Patients of the high-risk group with a suppressive immunological intratumor context were more sensitive to a broad range of antitumor agents. In contrast, low-risk individuals with active immune function responded more favorably to immunotherapy.

CONCLUSION

Our findings provided a novel and effective model for predicting BRCA prognosis and the propensity to different treatment modalities, thus contributing to the optimization of personalized BRCA therapy in the future.

Influence of chemoradiation on the immune microenvironment of cervical cancer patients

PURPOSE

Cervical cancer remains a leading cause of cancer death in women. While immunotherapy has shown great success in combating cancer, the value of immunotherapy in cervical cancer is still only beginning to be explored. Thus, we performed a prospective analysis of patient blood and tumor samples at the beginning and end of conventional chemoradiation to assess changes in the immune cell and immunoreceptor compartments, and investigate if and when the addition of immunotherapy could be beneficial.

METHODS

Patients with FIGO II-III cervical cancer receiving standard chemoradiation between January 2020 and December 2021 were included. We collected tumor and blood samples from patients before and at the end of therapy and analyzed immune cell composition and immune checkpoint receptor expression on both immune and tumor cells using multicolor flow cytometry.

RESULTS

In all, 34 patients were eligible in the study period; 22 could be included and analyzed in this study. We found that chemoradiation significantly reduces T cell numbers in both tumors and blood, but increases macrophage and neutrophil numbers in tumors. Furthermore, we found that the percentage of immune checkpoint receptor PD‑1 and TIGIT-expressing cells in tumors was significantly reduced at the end of therapy and that CD4 and CD8 memory T cell populations were altered by chemoradiation. In addition, we observed that while PD-L1 expression intensity was upregulated by chemoradiation on blood CD8 cells, PD-L1 expression frequency and the expression intensity of antigen-presenting molecule MHC‑I were significantly reduced on tumor cells.

CONCLUSION

Our data demonstrate that chemoradiation significantly alters the immune cell composition of human cervical tumors and the expression of immune checkpoint receptors on both lymphocytes and tumor cells. As our results reveal that the percentage of PD‑1⁺ CD8 cells in the tumor as well as the frequency of PD-L1-expressing tumor cells were reduced at the end of therapy, neoadjuvant or simultaneous anti-PD‑1 or anti-PD-L1 treatment might provide better treatment efficiency in upcoming clinical studies.

Immunotherapy for Meningiomas

Systemic treatment approaches are urgently needed for a subset of meningioma patients who do not achieve local tumor control with surgery and radiotherapy. Classical chemotherapy or anti-angiogenic agents exert only very limited activity in these tumors. Long-term survival of patients with advanced metastatic cancer following treatment with immune checkpoint inhibitors, i.e., monoclonal antibodies designed to unleash suppressed anticancer immune responses, has fostered hopes for benefit from similar approaches in patients with meningiomas that recur after standard local therapy. Moreover, a plethora of immunotherapy approaches beyond these drugs have entered clinical development or clinical practice for other cancer entities, including (i) novel immune checkpoint inhibitors that may act independently of T cell activity, (ii) cancer peptide or dendritic cell vaccines to induce anticancer immunity utilizing cancer-associated antigens, (iii) cellular therapies utilizing genetically modified peripheral blood cells to directly target cancer cells, (iv) T cell engaging recombinant proteins that link tumor antigen-binding sites to effector cell activating or recognition domains, or to immunogenic cytokines, and (v) oncolytic virotherapy utilizing attenuated viral vectors designed to specifically infect cancer cells, seeking to elicit systemic anticancer immunity. This chapter provides an overview of the principles of immunotherapy, summarizes ongoing immunotherapy clinical trials in meningioma patients, and discusses the applicability of established and emerging immunotherapy concepts to meningioma patients.

A Potential Off-Target Effect of the Wnt/β-Catenin Inhibitor KYA1797K: PD-L1 Binding and Checkpoint Inhibition

Introduction

The quest for small molecule inhibitors of the PD-1/PD-L1 checkpoint continues in parallel to the extensive development of monoclonal antibodies directed against this immune checkpoint. Drug screening strategies are being set up to identify novel PD-L1 inhibitors.

Methods

A virtual screening based on molecular docking with the PD-L1 protein dimer has been performed to identify a new binder. Binding of the identified ligand to PD-L1 has been validated experimentally using a microscale thermophoresis (MST) assay. The cellular effect of the compound was evidenced using a fluorescence resonance energy transfer (FRET) assay based on activation of tyrosine phosphatase SHP-2.

Results

We have identified the potent Wnt/β-catenin inhibitor KYA1797K as a weak PD-L1 binder. Molecular docking suggested that the compound can bind to the interface of a PD-L1 dimer, with a geometry superimposable to that of the reference PD-L1 inhibitor BMS-202. The atypical 2-thioxo-4-thiazolidinone motif of KYA1797K, derived from the natural product rhodanine, plays a major role in the interaction with PD-L1. Binding of KYA1797K to recombinant hPD-L1 was validated experimentally, using MST. The drug was found to bind modestly but effectively to hPD-L1. The FRET assay confirmed the weak capacity of KYA1797K to interfere with the activation of SHP-2 upon its interaction with human PD-1.

Discussion

Collectively, the data show that KYA1797K could function as a weak modulator of the PD-1/PD-L1 checkpoint. This effect may contribute, at least partially, to the reported capacity of the β-catenin inhibitor to downregulate PD-L1 in cancer cells. The work also underlines the interest to further consider the rhodanine moiety as a chemical motif for the design of new PD-L1 binders.

Novel immunogenic cell death-related risk signature to predict prognosis and immune microenvironment in lung adenocarcinoma

PURPOSE

Immunogenic cell death (ICD) is a type of regulated cell death (RCD) which was discovered to activate adaptive immunity. To date, the effect of ICD on lung adenocarcinoma (LUAD) remains unclear. In this research, we will study the role of ICD-related genes (ICDG) in LUAD.

METHODS

RNA sequencing and clinical data were gathered from TCGA-LUAD cohorts and GEO database. Using unsupervised cluster analysis, three clusters were identified with distinctive immune characteristics and significant overall survival based on 18 ICDG. Using LASSO Cox regression, three genes were identified and used to construct the prognosis signature. The association between the 3-ICDG risk signature and immune microenvironment analysis, somatic mutation, and enriched molecular pathways was investigated.

RESULTS

Consensus clustering separated the LUAD samples into three clusters (ICDcluster A, B and C), and ICDcluster B had the best prognosis. Different TME cell infiltration characteristics and biological behavior were found in three ICD clusters. Prognostic risk model was contrasted based on the 3 best prognostic ICD-related genes. Subsequently, vitro experiments verified the above analysis results. The high-risk group showed a poor prognosis and enrichment of cancer promoting signal pathway. Multivariate analysis indicated that this 3-ICDG prognostic model might be an accurate prediction parameter for LUAD. Moreover, conducting immune related analysis, we found that the 3-ICDG risk signature was characterized by an immune-active subtype on account of the high infiltration of immune-active cells.

CONCLUSION

This study expands our cognition of ICD in LUAD microenvironment, excavated prognostic biomarkers, and provided potential value for guiding immunotherapy and chemotherapy.