Immunoregulatory functions of VISTA

Immune checkpoint for pregnancy

A successful pregnancy relies on the precise regulation of the maternal immune system to recognize and tolerate the allogeneic fetus, while simultaneously preventing infection. Immune checkpoint molecules (ICMs), such as programmed death receptor 1 (PD-1), cytotoxic T-lymphocyte antigen 4 (CTLA-4), T cell immunoglobulin, and mucin-domain containing-3 (Tim-3), play critical roles in regulating the immune response during pregnancy. Emerging research highlights the therapeutic potential of targeting these molecules to restore the immune balance in complicated pregnancies. Understanding the dynamic regulation of ICMs during pregnancy may provide new insights into the pathogenesis of these conditions and offer novel approaches for clinical interventions. Here, we review the expression patterns and functions of key ICMs at the maternal-fetal interface, and their involvement in maintaining immune tolerance throughout gestation. Additionally, we describe the current understanding of immune checkpoint pathways in the pathogenesis of complicated pregnancies and discuss the potential for therapeutic targeting of these pathways in this setting.

FOXO1 pathway activation by VISTA immune checkpoint restrains pulmonary ILC2 functions

Group 2 innate lymphoid cells (ILC2s) play a pivotal role in the development of airway hyperreactivity (AHR). However, the regulatory mechanisms governing ILC2 function remain inadequately explored. This study uncovers V-domain Ig suppressor of T cell activation (VISTA) as an inhibitory immune checkpoint crucial for modulating ILC2-driven lung inflammation. VISTA is upregulated in activated pulmonary ILC2s and plays a key role in regulating lung inflammation, as VISTA-deficient ILC2s demonstrate increased proliferation and function, resulting in elevated type 2 cytokine production and exacerbation of AHR. Mechanistically, VISTA stimulation activates Forkhead box O1 (FOXO1), leading to modulation of ILC2 proliferation and function. The suppressive effects of FOXO1 on ILC2 effector function were confirmed using FOXO1 inhibitors and activators. Moreover, VISTA-deficient ILC2s exhibit enhanced fatty acid oxidation and oxidative phosphorylation to meet their high energy demands. Therapeutically, VISTA agonist treatment reduces ILC2 function both ex vivo and in vivo, significantly alleviating ILC2-driven AHR. Our murine findings were validated in human ILC2s, whose function was reduced ex vivo by a VISTA agonist, and in a humanized mouse model of ILC2-driven AHR. Our studies unravel VISTA as an immune checkpoint for ILC2 regulation via the FOXO1 pathway, presenting potential therapeutic strategies for allergic asthma by modulating ILC2 responses.

VISTA in hematological malignancies: a review of the literature

In recent years, tumor immunotherapy has become an active research area, with the emergence of immune checkpoint inhibitors (ICIs) revolutionizing immunotherapy. Clinical evidence indicates that programmed cell death protein 1 (PD-1) monoclonal antibodies and other drugs have remarkable therapeutic effects. V-domain Ig suppressor of T-cell activation (VISTA) is a new type of immune checkpoint receptor that is highly expressed in various tumors. It is co-expressed with PD-1, T-cell immunoglobulin domain, mucin domain-3 (Tim-3), T-cell immunoglobulin, and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT) and is associated with prognosis, which suggests that it may be a target for immunotherapy. As an immune checkpoint receptor with no mature drugs, VISTA is highly expressed in acute myeloid leukemia (AML), multiple myeloma (MM), and other hematological malignancies; however, its pathogenic mechanism should be defined to better guide treatment.

A pair of promising immune checkpoints PSGL-1 and VISTA from immunotolerance to immunotherapy

Immune checkpoints are crucial for regulating immune responses and maintaining self-tolerance, as they play a pivotal role in preventing autoimmunity and facilitating tumor immune evasion. This review concentrates on the immune checkpoint molecules PSGL-1 and VISTA. Both molecules are highly expressed in hematopoietic cells, including T cells and myeloid cells. VISTA functions both as a ligand on myeloid cells, where it regulates cytokine production, chemotaxis, and phagocytosis while promoting their differentiation into a tolerogenic phenotype and as a receptor on T cells, where it contributes to T cell quiescence. PSGL-1, which acts as a binding partner for VISTA, further inhibits T-cell activation and fosters tolerance within the acidic tumor microenvironment. Our review provides a comprehensive analysis of the structure, expression, and biological functions of PSGL-1 and VISTA and emphasizes their therapeutic potential in cancer treatment, autoimmune diseases, and transplantation. The dual role of these checkpoints in immune regulation presents novel opportunities for advancing cancer immunotherapy and developing new strategies for managing autoimmune conditions.

Targeting Dectin-1 and or VISTA enhances anti-tumor immunity in melanoma but not colorectal cancer model

PURPOSE

Acquired resistance to immune checkpoint blockers (ICBs) is a major barrier in cancer treatment, emphasizing the need for innovative strategies. Dectin-1 (gene Clec7a) is a C-type lectin receptor best known for its ability to recognize β-glucan-rich structures in fungal cell walls. While Dectin-1 is expressed in myeloid cells and tumor cells, its significance in cancer remains the subject of controversy.

METHODS

Using Celc7a-/- mice and curdlan administration to stimulate Dectin-1 signaling, we explored its impact. VISTA KO mice were employed to assess VISTA's role, and bulk RNAseq analyzed curdlan effects on neutrophils.

RESULTS

Our findings reveal myeloid cells as primary Dectin-1 expressing cells in the tumor microenvironment (TME), displaying an activated phenotype. Strong Dectin-1 co-expression/co-localization with VISTA and PD-L1 in TME myeloid cells was observed. While Dectin-1 deletion lacked protective effects, curdlan stimulation significantly curtailed B16-F10 tumor progression. RNAseq and pathway analyses supported curdlan's role in triggering a cascade of events leading to increased production of pro-inflammatory mediators, potentially resulting in the recruitment and activation of immune cells. Moreover, we identified a heterogeneous subset of Dectin-1+ effector T cells in the TME. Similar to mice, human myeloid cells are the prominent cells expressing Dectin-1 in cancer patients.

CONCLUSION

Our study proposes Dectin-1 as a potential adjunctive target with ICBs, orchestrating a comprehensive engagement of innate and adaptive immune responses in melanoma. This innovative approach holds promise for overcoming acquired resistance to ICBs in cancer treatment, offering avenues for further exploration and development.

The miRNA and PD-1/PD-L1 signaling axis: an arsenal of immunotherapeutic targets against lung cancer

Lung cancer is a severe challenge to the health care system with intrinsic resistance to first and second-line chemo/radiotherapies. In view of the sterile environment of lung cancer, several immunotherapeutic drugs including nivolumab, pembrolizumab, atezolizumab, and durvalumab are currently being used in clinics globally with the intention of releasing exhausted T-cells back against refractory tumor cells. Immunotherapies have a limited response rate and may cause immune-related adverse events (irAEs) in some patients. Hence, a deeper understanding of regulating immune checkpoint interactions could significantly enhance lung cancer treatments. In this review, we explore the role of miRNAs in modulating immunogenic responses against tumors. We discuss various aspects of how manipulating these checkpoints can bias the immune system's response against lung cancer. Specifically, we examine how altering the miRNA profile can impact the activity of various immune checkpoint inhibitors, focusing on the PD-1/PD-L1 pathway within the complex landscape of lung cancer. We believe that a clear understanding of the host's miRNA profile can influence the efficacy of checkpoint inhibitors and significantly contribute to existing immunotherapies for lung cancer patients. Additionally, we discuss ongoing clinical trials involving immunotherapeutic drugs, both as standalone treatments and in combination with other therapies, intending to advance the development of immunotherapy for lung cancer.

Eliminating a barrier: Aiming at VISTA, reversing MDSC-mediated T cell suppression in the tumor microenvironment

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment by producing remarkable clinical outcomes for patients with various cancer types. However, only a subset of patients benefits from immunotherapeutic interventions due to the primary and acquired resistance to ICIs. Myeloid-derived suppressor cells (MDSCs) play a crucial role in creating an immunosuppressive tumor microenvironment (TME) and contribute to resistance to immunotherapy. V-domain Ig suppressor of T cell activation (VISTA), a negative immune checkpoint protein highly expressed on MDSCs, presents a promising target for overcoming resistance to current ICIs. This article provides an overview of the evidence supporting VISTA's role in regulating MDSCs in shaping the TME, thus offering insights into how to overcome immunotherapy resistance.

Advances in immunotherapy for breast cancer and feline mammary carcinoma: From molecular basis to novel therapeutic targets

The role of inflammation in cancer is a topic that has been investigated for many years. As established, inflammation emerges as a defining characteristic of cancer, presenting itself as a compelling target for therapeutic interventions in the realm of oncology. Controlling the tumor microenvironment (TME) has gained paramount significance, modifying not only the effectiveness of immunotherapy but also modulating the outcomes and prognoses of standard chemotherapy and other anticancer treatments. Immunotherapy has surfaced as a central focus within the domain of tumor treatments, using immune checkpoint inhibitors as cancer therapy. Immune checkpoints and their influence on the tumor microenvironment dynamic are presently under investigation, aiming to ascertain their viability as therapeutic interventions across several cancer types. Cancer presents a significant challenge in humans and cats, where female breast cancer ranks as the most prevalent malignancy and feline mammary carcinoma stands as the third most frequent. This review seeks to summarize the data about the immune checkpoints cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), lymphocyte activation gene-3 (LAG-3), programmed cell death protein-1 (PD-1), V-domain Ig suppressor of T cell activation (VISTA), and T-cell immunoglobulin and mucin domain 3 (TIM-3) respective ongoing investigations as prospective targets for therapy for human breast cancer, while also outlining findings from studies reported on feline mammary carcinoma (FMC), strengthening the rationale for employing FMC as a representative model in the exploration of human breast cancer.

Surface Immune Checkpoints as Potential Biomarkers in Physiological Pregnancy and Recurrent Pregnancy Loss

Due to the genetic diversity between the mother and the fetus, heightened control over the immune system during pregnancy is crucial. Immunological parameters determined by clinicians in women with idiopathic recurrent spontaneous abortion (RSA) include the quantity and activity of Natural Killer (NK) and Natural Killer T (NKT) cells, the quantity of regulatory T lymphocytes, and the ratio of pro-inflammatory cytokines, which indicate imbalances in Th1 and Th2 cell response. The processes are controlled by immune checkpoint proteins (ICPs) expressed on the surface of immune cells. We aim to investigate differences in the expression of ICPs on T cells, T regulatory lymphocytes, NK cells, and NKT cells in peripheral blood samples collected from RSA women, pregnant women, and healthy multiparous women. We aim to discover new insights into the role of ICPs involved in recurrent pregnancy loss. Peripheral blood mononuclear cells (PBMCs) were isolated by gradient centrifugation from blood samples obtained from 10 multiparous women, 20 pregnant women (11-14th week of pregnancy), and 20 RSA women, at maximum of 72 h after miscarriage. The PBMCs were stained for flow cytometry analysis. Standard flow cytometry immunophenotyping of PBMCs was performed using antibodies against classical lymphocyte markers, including CD3, CD4, CD8, CD56, CD25, and CD127. Additionally, ICPs were investigated using antibodies against Programmed Death Protein-1 (PD-1, CD279), T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3, CD366), V-domain Ig suppressor of T cell activation (VISTA), T cell immunoglobulin and ITIM domain (TIGIT), and Lymphocyte activation gene 3 (LAG-3). We observed differences in the surface expression of ICPs in the analyzed subpopulations of lymphocytes between early pregnancy and RSA, after miscarriage, and in women. We noted diminished expression of PD-1 on T lymphocytes (p = 0.0046), T helper cells (CD3CD4 positive cells, p = 0.0165), T cytotoxic cells (CD3CD8 positive cells, p = 0.0046), T regulatory lymphocytes (CD3CD4CD25CD127 low positive cells, p = 0.0106), and NKT cells (CD3CD56/CD16 positive cells, p = 0.0438), as well as LAG-3 on lymphocytes T (p = 0.0225) T helper, p = 0.0426), T cytotoxic cells (p = 0.0458) and Treg (p = 0.0293), and cells from RSA women. Impaired expression of TIM-3 (p = 0.0226) and VISTA (p = 0.0039) on CD8 cytotoxic T and NK (TIM3 p = 0.0482; VISTA p = 0.0118) cells was shown, with an accompanying increased expression of TIGIT (p = 0.0211) on NKT cells. The changes in the expression of surface immune checkpoints indicate their involvement in the regulation of pregnancy. The data might be utilized to develop specific therapies for RSA women based on the modulation of ICP expression.

VISTA: A Novel Checkpoint for Cancer Immunotherapy

V-domain Ig suppressor of T cell activation (VISTA) is a recently identified member of the B7 family of immunoregulatory proteins. It is pivotal for maintaining T cell quiescence and exerts a significant regulatory influence on the immune response to tumors. Accumulating clinical evidence suggests that the influence of VISTA on tumor immunity is more nuanced than initially postulated. Although these revelations add layers of complexity to our understanding of the function of VISTA, they also offer novel avenues for scientific inquiry and potential therapeutic targets. In this review, we scrutinize the current literature pertaining to the expression of VISTA in various of malignancies, aiming to elucidate its intricate roles within the tumor microenvironment and in cancer immunotherapy.

Comprehensive characterization of B7 family members in breast cancer: B7-H5 switch reverses breast cancer from "immuno-cold" into "immuno-hot" status

The members of the classic B7 family regulate the immune microenvironment of several malignant tumors. However, the potential relationship between the B7 family and the breast cancer (BrCa) tumor immune microenvironment has remained elusive. In the present study, we provide a comprehensive explanation of the expression, clinical significance, mutation, and immune cell infiltration of B7 family molecules in BrCa. First, we recruited 10 patients with BrCa surgery from the Wuxi Maternal and Child Health Hospital and performed single-cell RNA sequencing (scRNA-seq) analysis to investigate the distribution of B7 family members in multiple immune cell subsets. We focused on B7-2, B7-H3, and B7-H5 molecules of the B7 family and constructed tumor microarrays by self-recruiting patients to perform multiple immunohistochemical (mIHC) analyses and study tumor expression of B7-2, B7-H3, B7-H5 and CD8+ immune cell infiltration. B7-H5 displayed a strong correlation with CD8+ immune cell infiltration. In summary, B7-H5 provides a new perspective for the identification of immunothermal subtypes of BrCa and could function as a switch to reverse BrCa from an "immunologically cold" state to an "immunologically hot" state.

VISTA nonredundantly regulates proliferation and CD69low γδ T cell accumulation in the intestine in murine sepsis

Sepsis is a dysregulated systemic immune response to infection i.e. responsible for ∼35% of in-hospital deaths at a significant fiscal healthcare cost. Our laboratory, among others, has demonstrated the efficacy of targeting negative checkpoint regulators (NCRs) to improve survival in a murine model of sepsis, cecal ligation and puncture (CLP). B7-CD28 superfamily member, V-domain immunoglobulin suppressor of T cell activation (VISTA), is an ideal candidate for strategic targeting in sepsis. VISTA is a 35 to 45 kDa type 1 transmembrane protein with unique biology that sets it apart from all other NCRs. We recently reported that VISTA-/- mice had a significant survival deficit post-CLP, which was rescued upon adoptive transfer of a VISTA-expressing pMSCV-mouse Foxp3-EF1α-GFP-T2A-puro stable Jurkat cell line (Jurkatfoxp3 T cells). Based on our prior study, we investigated the effector cell target of Jurkatfoxp3 T cells in VISTA-/- mice. γδ T cells are a powerful lymphoid subpopulation that require regulatory fine-tuning by regulatory T cells to prevent overt inflammation/pathology. In this study, we hypothesized that Jurkatfoxp3 T cells nonredundantly modulate the γδ T cell population post-CLP. We found that VISTA-/- mice have an increased accumulation of intestinal CD69low γδ T cells, which are not protective in murine sepsis. Adoptive transfer of Jurkatfoxp3 T cells decreased the intestinal γδ T cell population, suppressed proliferation, skewed remaining γδ T cells toward a CD69high phenotype, and increased soluble CD40L in VISTA-/- mice post-CLP. These results support a potential regulatory mechanism by which VISTA skews intestinal γδ T cell lineage representation in murine sepsis.

VISTA/CTLA4/PD1 coexpression on tumor cells confers a favorable immune microenvironment and better prognosis in high-grade serous ovarian carcinoma

Introduction

Immunotherapy by blocking immune checkpoints programmed death/ligand (PD1/PDL1) and cytotoxic T-lymphocyte-associated protein 4(CTLA4) has emerged as new therapeutic targets in cancer. However, their efficacy has been limited due to resistance. A new- checkpoint V-domain Ig-containing suppressor of T cell activation (VISTA) has appeared, but the use of its inhibition effect in combination with antibodies targeting PDL1/PD1and CTLA4 has not been reported in ovarian cancer.

Methods

In this study, we investigated the expressions of VISTA, CTLA4, and PDL1 using immunohistochemistry (IHC)on 135 Formalin-Fixed Paraffin-Embedded (FFPE)tissue samples of High-grade serous carcinoma (HGSOC). VISTA, CTLA4, PDL1, PD1, CD8, CD4, and FOXP3 mRNA extracted from 429 patients with ovarian cancer in the Cancer Genome Atlas (TCGA) database was included as a validation cohort. Correlations between these checkpoints, tumor-infiltrating- lymphocytes (TILs), and survival were analyzed.

Results and discussion

CTLA4 was detectable in 87.3% of samples, VISTA in 64.7%, PD1 in 56.7%, and PDL1 in 48.1%. PDL1 was the only tested protein associated with an advanced stage (p=0.05). VISTA was associated with PDL1, PD1, and CTLA4 expressions (p=0.005, p=0.001, p=0.008, respectively), consistent with mRNA level analysis from the TCGA database. Univariate analyses showed only VISTA expression (p=0.04) correlated with overall survival (OS). Multivariate analyses showed that VISTA expression (p=0.01) and the coexpression of VISTA+/CTLA4+/PD1+ (p=0.05) were associated with better OS independently of the clinicopathological features. Kaplan-Meier analysis showed that the coexpression of the VISTA+/CTLA4+/PDL1+ and VISTA+/CTLA4+/PD1+ checkpoints on tumor cells (TCs)were associated with OS (p=0.02 and p<0.001; respectively). VISTA+/CTLA4+/PD1+ in TCs and CD4+/CD8+TILswere associated with better 2-yer OS. This correlation may refer to the role of VISTA as a receptor in the TCs and not in the immune cells. Thus, targeting combination therapy blocking VISTA, CTLA4, and PD1 could be a novel and attractive strategy for HGSOC treatment, considering the ambivalent role of VISTA in the HGSOC tumor cells.

Therapeutic and immunomodulatory potentials of mesenchymal stromal/stem cells and immune checkpoints related molecules

Mesenchymal stromal/stem cells (MSCs) are used in many studies due to their therapeutic potential, including their differentiative ability and immunomodulatory properties. These cells perform their therapeutic functions by using various mechanisms, such as the production of anti-inflammatory cytokines, growth factors, direct cell-to-cell contact, extracellular vesicles (EVs) production, and mitochondrial transfer. However, mechanisms related to immune checkpoints (ICPs) and their effect on the immunomodulatory ability of MSCs are less discussed. The main function of ICPs is to prevent the initiation of unwanted responses and to regulate the immune system responses to maintain the homeostasis of these responses. ICPs are produced by various types of immune system regulatory cells, and defects in their expression and function may be associated with excessive responses that can ultimately lead to autoimmunity. Also, by expressing different types of ICPs and their ligands (ICPLs), tumor cells prevent the formation and durability of immune responses, which leads to tumors' immune escape. ICPs and ICPLs can be produced by MSCs and affect immune cell responses both through their secretion into the microenvironment or direct cell-to-cell interaction. Pre-treatment of MSCs in inflammatory conditions leads to an increase in their therapeutic potential. In addition to the effect that inflammatory environments have on the production of anti-inflammatory cytokines by MSCs, they can increase the expression of various types of ICPLs. In this review, we discuss different types of ICPLs and ICPs expressed by MSCs and their effect on their immunomodulatory and therapeutic potential.

Phytochemicals in regulating PD-1/PD-L1 and immune checkpoint blockade therapy

Clinical treatment and preclinical studies have highlighted the role of immune checkpoint blockade in cancer treatment. Research has been devoted to developing immune checkpoint inhibitors in combination with other drugs to achieve better efficacy or reduce adverse effects. Phytochemicals sourced from vegetables and fruits have demonstrated antiproliferative, proapoptotic, anti-migratory, and antiangiogenic effects against several cancers. Phytochemicals also modulate the tumor microenvironment such as T cells, regulatory T cells, and cytokines. Recently, several phytochemicals have been reported to modulate immune checkpoint proteins in in vivo or in vitro models. Phytochemicals decreased programmed cell death ligand-1 expression and synergized programmed cell death receptor 1 (PD-1) monoclonal antibody to suppress tumor growth. Combined administration of phytochemicals and PD-1 monoclonal antibody enhanced the tumor growth inhibition as well as CD4+ /CD8+ T-cell infiltration. In this review, we discuss immune checkpoint molecules as potential therapeutic targets of cancers. We further assess the impact of phytochemicals including carotenoids, polyphenols, saponins, and organosulfur compounds on cancer PD-1/programmed cell death ligand-1 immune checkpoint molecules and document their combination effects with immune checkpoint inhibitors on various malignancies.

Low expression of PRRG2 in kidney renal clear cell carcinoma: an immune infiltration-associated prognostic biomarker

OBJECTIVE

This study aims to explore the prognostic significance of Proline-rich γ-carboxyglutamic acid protein 2 (PRRG2) in Kidney Renal Clear Cell Carcinoma (KIRC), a prevalent and deadly cancer, and its association with immune cell infiltration, a key strategy in developing effective biomarkers.

METHODS

The study meticulously elucidated the prognostic significance and potential role of PRRG2 in KIRC, correlating its expression with patient sex, age, metastasis, and pathological stage. Utilizing Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA), the involvement of PRRG2 in immune response was investigated. The association between PRRG2 expression and immune cell infiltration was also scrutinized. Ultimately, cellular and tissue identity were confirmed via immunohistochemical staining and quantitative real-time PCR.

RESULTS

The study elucidates a notable decrease in PRRG2 expression in KIRC patients, correlating with demographic factors, metastasis, and pathological staging, and portending an unfavorable prognosis. Bioinformatic analyses underscore PRRG2's role in immune response, with its expression significantly tied to immune cell infiltration and marker expression.

CONCLUSION

PRRG2 may potentially impact prognosis in KIRC patients by regulating immune infiltration, thus rendering PRRG2 a promising candidate prognostic biomarker for KIRC-associated immune infiltration.

Aldehyde dehydrogenase 2-mediated aldehyde metabolism promotes tumor immune evasion by regulating the NOD/VISTA axis

BACKGROUND

Aldehyde dehydrogenase 2 (ALDH2) is a crucial enzyme involved in endogenous aldehyde detoxification and has been implicated in tumor progression. However, its role in tumor immune evasion remains unclear.

METHODS

Here, we analyzed the relationship between ALDH2 expression and antitumor immune features in multiple cancers. ALDH2 knockout tumor cells were then established using CRISPR/Cas9 system. In immunocompetent breast cancer EMT6 and melanoma B16-F10 mouse models, we investigated the impact of ALDH2 blockade on cytotoxic T lymphocyte function and tumor immune microenvironment by flow cytometry, mass cytometry, Luminex liquid suspension chip detection, and immunohistochemistry. Furthermore, RNA sequencing, flow cytometry, western blot, chromatin immunoprecipitation assay, and luciferase reporter assays were employed to explore the detailed mechanism of ALDH2 involved in tumor immune evasion. Lastly, the synergistic therapeutic efficacy of blocking ALDH2 by genetic depletion or its inhibitor disulfiram in combination with immune checkpoint blockade (ICB) was investigated in mouse models.

RESULTS

In our study, we uncovered a positive correlation between the expression level of ALDH2 and T-cell dysfunction in multiple cancers. Furthermore, blocking ALDH2 significantly suppressed tumor growth by enhancing cytotoxic activity of CD8+ T cells and reshaping the immune landscape and cytokine milieu of tumors in vivo. Mechanistically, inhibiting ALDH2-mediated metabolism of aldehyde downregulated the expression of V-domain Ig suppressor of T-cell activation (VISTA) via inactivating the nucleotide oligomerization domain (NOD)/nuclear factor kappa-B (NF-κB) signaling pathway. As a result, the cytotoxic function of CD8+ T cells was revitalized. Importantly, ALDH2 blockade markedly reinforced the efficacy of ICB treatment.

CONCLUSIONS

Our data delineate that ALDH2-mediated aldehyde metabolism drives tumor immune evasion by activating the NOD/NF-κB/VISTA axis. Targeting ALDH2 provides an effective combinatorial therapeutic strategy for immunotherapy.

Expression analysis of inhibitory B7 family members in Alzheimer's disease

Alzheimer's disease (AD) is a global health problem due to its complexity, which frequently makes the development of treatment methods extremely difficult. Therefore, new methodologies are necessary to investigate the pathophysiology of AD and to treat AD. The interaction of immune modulation and neurodegeneration has added new dimensions in current knowledge of AD etiology and offers an attractive opportunity for the discovery of novel biomarkers and therapies. Using quantitative polymerase chain reaction, we compared the expression levels of inhibitory B7 family members (B7-1, B7-2, B7-H1, B7-DC, B7-H3, B7-H4, B7-H5, B7-H7, and ILDR2), as immune regulators, in the peripheral blood of late-onset AD (LOAD) patients (n = 50) and healthy individuals (n = 50). The levels of B7-2, B7-H4, ILDR2, and B7-DC expression were significantly higher in-patient blood samples than in control blood samples. Furthermore, we discovered a substantial positive correlation between all gene expression levels. In addition, the current study indicated that ILDR2, B7-H4, B7-2, and B7-DC might serve as diagnostic biomarkers to identify LOAD patients from healthy persons. The present work provides additional evidence for the significance of inhibitory B7 family members to the etiology of LOAD.

Imatinib and M351-0056 enhance the function of VISTA and ameliorate the development of SLE via IFN-I and noncanonical NF-κB pathway

V-domain immunoglobulin suppressor of T-cell activation (VISTA), an important negative checkpoint protein, participates in immunoregulation. Systemic lupus erythematosus (SLE) is an autoimmune disease in which patients exhibit high levels of autoantibodies and multi-organ tissue injury, primarily involving the kidney and skin. In wild-type (WT) mice and Vsir-/- mice with pristane-induced lupus-like disease, we found that VISTA deficiency exacerbated the lupus-like disease in mice, possibly through aberrant activation of type I interferon (IFN-I) signaling, CD4+ T cell, and noncanonical nuclear factor-κB (NF-κB) pathway. Surface plasmon resonance results showed that imatinib, an FDA-approved tyrosine kinase inhibitor, may have a high affinity for human VISTA-ECD with a KD value of 0.2009 μM. The biological activities of imatinib and VISTA agonist M351-0056 were studied in monocytes and T cells and in lupus-like disease murine model of chronic graft-versus-host disease (cGVHD) and lupus-prone MRL/lpr mice. VISTA small-molecule agonist reduced the cytokine production of peripheral blood mononuclear cells (PBMCs) and Jurkat cells and inhibited PBMCs proliferation. Moreover, they attenuated the levels of autoantibodies, renal injury, inflammatory cytokines, chemokines, and immune cell expansion in the cGVHD mouse model and MRL/lpr mice. Our findings also demonstrated that VISTA small-molecule agonist ameliorated the development of SLE through improving aberrantly activated IFN-I signaling and noncanonical NF-κB pathway. In conclusion, VISTA has a protective effect on the development and progression of SLE. VISTA agonist M351-0056 and imatinib have been firstly demonstrated to attenuate SLE, suggesting interventions to enhance VISTA function may be effective in treating SLE. VISTA deficiency exacerbates pristane-induced lupus-like disease in mice by promoting activation of the IFN-I and noncanonical NF-κB pathway. Imatinib was screened as a small-molecule VISTA agonist by molecular docking, SPR, and cellular level experiments. VISTA agonists (M351-0056 and imatinib) alleviated lupus-like disease progression in the cGVHD mouse model and MRL/lpr mice by inhibiting activation of IFN-I and noncanonical NF-κB pathway.

Charting new frontiers: Co-inhibitory immune checkpoint proteins in therapeutics, biomarkers, and drug delivery systems in cancer care

Cancer remains a major health concern globally. Immune checkpoint inhibitors (ICIs) target co-inhibitory immune checkpoint molecules and have received approval for treating malignancies like melanoma and non-small cell lung cancer. While CTLA-4 and PD-1/PD-L1 are extensively researched, additional targets such as LAG-3, TIGIT, TIM-3, and VISTA have also demonstrated effective in cancer therapy. Combination treatments, which pair ICIs with interventions such as radiation or chemotherapy, amplify therapeutic outcomes. However, ICIs can lead to diverse side effects, and their varies across patients and cancers. Hence, identifying predictive biomarkers to guide therapy is essential. Notably, expression levels of molecules like PD-1, CTLA-4, and LAG-3 have been linked to tumor progression and ICI therapy responsiveness. Recent advancements in drug delivery systems (DDSs) further enhance ICI therapy efficacy. This review explores predominant DDSs for ICI delivery, such as hydrogel, microparticle, and nanoparticle, which offer improved therapeutic effects and reduced toxicity. In summary, we discuss the future of immune therapy focusing on co-inhibitory checkpoint molecules, pinpoint challenges, and suggest avenues for developing efficient, safer DDSs for ICI transport.

Regulatory T cells in gastric cancer: Key controllers from pathogenesis to therapy

Gastric cancer (GC) is a highly aggressive malignancy that remains a significant contributor to cancer-related mortality worldwide, despite a decline in incidence in recent years. Early-stage GC poses a diagnostic challenge due to its asymptomatic nature, leading to poor prognoses for most patients. Conventional treatment approaches, including chemotherapy and surgery, have shown limited efficacy in improving outcomes for GC patients. The advent of immune checkpoint inhibitors (ICIs) has revolutionized cancer therapy, yielding durable responses across various malignancies. However, the clinical benefits of ICIs in GC have been modest, underscoring the need for a comprehensive understanding of immune cell functions within the GC tumor microenvironment (TME). Regulatory T cells (Tregs), a subset of T lymphocytes, play a pivotal role in GC development and progression and serve as prognostic biomarkers for GC patients. This review aims to elucidate the multifaceted roles of Tregs in the pathogenesis, progression, and prognosis of gastric cancer, and establish their actual and future potential as therapeutic targets. By providing insights into the intricate interplay between Tregs and the TME, this review strives to stimulate further investigation and facilitate the development of targeted Treg-based therapeutic strategies for GC.

Prognostic Factors in Advanced Non-Small Cell Lung Cancer Patients Treated with Immunotherapy

Taking into account the huge epidemiologic impact of lung cancer (in 2020, lung cancer accounted for 2,206,771 of the cases and for 1,796,144 of the cancer-related deaths, representing the second most common cancer in female patients, the most common cancer in male patients, and the second most common cancer in male and female patients) and the current lack of recommendations in terms of prognostic factors for patients selection and management, this article aims to provide an overview of the current landscape in terms of currently available immunotherapy treatments and the most promising assessed prognostic biomarkers, highlighting the current state-of-the-art and hinting at future challenges.

Clinical and research updates on the VISTA immune checkpoint: immuno-oncology themes and highlights

Immune checkpoints limit the activation of the immune system and serve an important homeostatic function but can also restrict immune responses against tumors. Inhibition of specific immune checkpoint proteins such as the B7:CD28 family members programmed cell death protein-1 (PD-1) and cytotoxic T-lymphocyte antigen-4 (CTLA-4) has transformed the treatment of various cancers by promoting the anti-tumor activation of immune cells. In contrast to these effects, the V-domain immunoglobulin suppressor of T-cell activation (VISTA) regulates the steady state of the resting immune system and promotes homeostasis by mechanisms distinct from PD-1 and CTLA-4. The effects of VISTA blockade have been shown to include a decrease in myeloid suppression coupled with proinflammatory changes by mechanisms that are separate and distinct from other immune checkpoint proteins; in some preclinical studies these immune effects appear synergistic. Given the potential benefits of VISTA blockade in the context of cancer therapy, the second Annual VISTA Symposium was convened virtually on September 23, 2022, to review new research from investigators and immuno-oncology experts. Discussions in the meeting extended the knowledge of VISTA biology and the effects of VISTA inhibition, particularly on cells of the myeloid lineage and resting T cells, as three candidate anti-VISTA antibodies are in, or nearing, clinical development.

Enhancement of Radiation Therapy through Blockade of the Immune Checkpoint, V-domain Ig Suppressor of T Cell Activation (VISTA), in Melanoma and Adenocarcinoma Murine Models

Radiation therapy (RT) has recently demonstrated promise at stimulating an enhanced immune response. The recent success of immunotherapies, such as checkpoint inhibitors, CART cells, and other immune modulators, affords new opportunities for combination with radiation. The aim of this study is to evaluate whether and to what extent blockade of VISTA, an immune checkpoint, can potentiate the tumor control ability of radiation therapy. Our study is novel in that it is the first comparison of two VISTA-blocking methods (antibody inhibition and genetic knockout) in combination with RT. VISTA was blocked either through genetic knockout (KO) or an inhibitory antibody and combined with RT in two syngeneic murine flank tumor models (B16 and MC38). Selected mRNA, immune cell infiltration, and tumor growth delay were used to assess the biological effects. When combined with a single 15Gy radiation dose, VISTA blockade via genetic knockout in the B16 model and via anti-VISTA antibodies in the MC38 model significantly improved survival compared to RT alone by an average of 5.5 days and 6.3 days, respectively (p < 0.05). The gene expression data suggest that the mechanism behind the enhanced tumor control is primarily a result of increased apoptosis and immune-mediated cytotoxicity. VISTA blockade significantly enhances the anti-tumor effect of a single dose of 15Gy radiation through increased expression and stimulation of cell-mediated apoptosis pathways. These results suggest that VISTA is a biologically relevant immune promoter that has the potential to enhance the efficacy of a large single radiation dose in a synergic manner.

Conditionally Active, pH-Sensitive Immunoregulatory Antibodies Targeting VISTA and CTLA-4 Lead an Emerging Class of Cancer Therapeutics

Immune checkpoints and other immunoregulatory targets can be difficult to precisely target due to expression on non-tumor immune cells critical to maintaining immune homeostasis in healthy tissues. On-target/off-tumor binding of therapeutics results in significant pharmacokinetic and pharmacodynamic problems. Target-mediated drug disposition (TMDD) significantly limits effective intratumoral drug levels and adversely affects anti-tumor efficacy. Target engagement outside the tumor environment may lead to severe immune-related adverse events (irAEs), resulting in a narrowing of the therapeutic window, sub-optimal dosing, or cessation of drug development altogether. Overcoming these challenges has become tractable through recent advances in antibody engineering and screening approaches. Here, we review the discovery and development of conditionally active antibodies with minimal binding to target at physiologic pH but high-affinity target binding at the low pH of the tumor microenvironment by focusing on the discovery and improved properties of pH-dependent mAbs targeting two T cell checkpoints, VISTA and CTLA-4.

Comparison of PD-L1 and VISTA expression status in primary and recurrent/refractory tissue after (chemo)radiotherapy in head and neck cancer

BACKGROUND

PD-L1 and VISTA are thought to play a role in escape from the immune system, tumor progression, and treatment response in tumoral tissue. The current study aimed to evaluate the effects of radiotherapy (RT) and chemoradiotherapy (CRT) on PD-L1 and VISTA expression in head and neck cancers.

METHODS

PD-L1 and VISTA expression were compared between the primary biopsy taken at the time of diagnosis and refractory tissue biopsies of patients who received definitive CRT or recurrent tissue biopsies of patients who had surgery followed by adjuvant RT or CRT.

RESULTS

In total, 47 patients were included. Radiotherapy had no effect on the expression levels of PD-L1 and VISTA in patients with head and neck cancer (p = 0.542 and p = 0.425, respectively). A positive correlation was found between PD-L1 and VISTA expression (p < 0.001; r = 0.560). PD-L1 and VISTA expression in the first biopsy were found to be significantly higher in clinical lymph node-positive patients compared to node-negative patients (PD-L1 p = 0.038; VISTA p = 0.018). The median overall survival of patients with ≥ 1% VISTA expression in the initial biopsy was significantly shorter than that of patients with < 1% VISTA expression (52.4 vs. 110.1 months, respectively; p = 0.048).

CONCLUSION

It was found that PD-L1 and VISTA expression did not change with RT or CRT. Further studies are needed to evaluate the relationship of PD-L1 and VISTA expression with RT and CRT.

Immune inactivation by VISTA predicts clinical outcome and therapeutic benefit in muscle-invasive bladder cancer

BACKGROUND

V domain Immunoglobulin suppressor of T cell activation (VISTA) has been proved to be a novel immune checkpoint molecule that positively regulates T cell infiltration in several malignancies. However, the clinical impact of VISTA on muscle-invasive bladder cancer (MIBC) patients remains relatively obscure.

METHODS

This study enrolled 135 MIBC patients from Zhongshan Hospital (ZSHS) and 391 patients from The Cancer Genome Atlas (TCGA) to examine the VISTA expression and immune contexture based on immunohistochemistry (IHC) staining and CIBERSORT algorithm. Additionally, IMvigor210 Cohort included 195 bladder-derived urothelial carcinoma patients to evaluate the efficacy of immunotherapy. Kaplan-Meier curve and Cox regression analyses were conducted to assess clinical outcomes.

RESULTS

MIBC patients with high VISTA⁺ immune cells (ICs) possessed poor overall survival and inferior therapeutic responsiveness to adjuvant chemotherapy (ACT), but superior responsiveness to PD-L1 inhibitor. VISTA⁺ ICs infiltration shaped an immunoevasive context featured by regulatory T cells (Tregs), M2 macrophages, mast cells and exhausted CD8⁺ T cells infiltration, with increased interleukin 10 (IL-10), transforming growth factor-β (TGF-β) and interferon-γ (IFN-γ), but also elevated T-cell immunoglobulin mucin-3 (TIM-3), lymphocyte activation gene 3 (LAG-3) and T-cell immunoglobulin and ITIM domain (TIGIT), which was also mainly presented in basal-squamous and luminal-infiltrated subtypes of MIBC.

CONCLUSION

VISTA⁺ ICs infiltration could be an independent predictor to identify poor prognosis and therapeutic responses (PD-L1 blockade and ACT) in MIBC patients, which was associated with immunoevasive contexture. The novel immune checkpoint VISTA might be utilized as a candidate treatment biomarker in MIBC patients.

Malignant mesothelioma tumours: molecular pathogenesis, diagnosis, and therapies accompanying clinical studies

The pathetic malignant mesothelioma (MM) is a extremely uncommon and confrontational tumor that evolves in the mesothelium layer of the pleural cavities (inner lining- visceral pleura and outer lining- parietal pleura), peritoneum, pericardium, and tunica vaginalis and is highly resistant to standard treatments. In mesothelioma, the predominant pattern of lesions is a loss of genes that limit tumour growth. Despite the worldwide ban on the manufacture and supply of asbestos, the prevalence of mesothelioma continues to increase. Mesothelioma presents and behaves in a variety of ways, making diagnosis challenging. Most treatments available today for MM are ineffective, and the median life expectancy is between 10 and 12 months. However, in recent years, considerable progress has already been made in understanding the genetics and molecular pathophysiology of mesothelioma by addressing hippo signaling pathway. The development and progression of MM are related to many important genetic alterations. This is related to NF2 and/or LATS2 mutations that activate the transcriptional coactivator YAP. The X-rays, CT scans, MRIs, and PET scans are used to diagnose the MM. The MM are treated with surgery, chemotherapy, first-line combination chemotherapy, second-line treatment, radiation therapy, adoptive T-cell treatment, targeted therapy, and cancer vaccines. Recent clinical trials investigating the function of surgery have led to the development of innovative approaches to the treatment of associated pleural effusions as well as the introduction of targeted medications. An interdisciplinary collaborative approach is needed for the effective care of persons who have mesothelioma because of the rising intricacy of mesothelioma treatment. This article highlights the key findings in the molecular pathogenesis of mesothelioma, diagnosis with special emphasis on the management of mesothelioma.

Immune-checkpoint protein VISTA in allergic, autoimmune disease and transplant rejection

Negative checkpoint regulators (NCRs) reduce the T cell immune response against self-antigens and limit autoimmune disease development. V-domain Ig suppressor of T cell activation (VISTA), a novel immune checkpoint in the B7 family, has recently been identified as one of the NCRs. VISTA maintains T cell quiescence and peripheral tolerance. VISTA targeting has shown promising results in treating immune-related diseases, including cancer and autoimmune disease. In this review, we summarize and discuss the immunomodulatory role of VISTA, its therapeutic potential in allergic, autoimmune disease, and transplant rejection, as well as the current therapeutic antibodies, to present a new method for regulating immune responses and achieving durable tolerance for the treatment of autoimmune disease and transplantation.

Vista of the Future: Novel Immunotherapy Based on the Human V-Set Immunoregulatory Receptor for Digestive System Tumors

While gastrointestinal tumors remain a multifactorial and prevalent group of malignancies commonly treated surgically in combination with chemotherapy and radiotherapy, advancements regarding immunotherapeutic approaches continue to occur. Entering a new era of immunotherapy focused on overcoming resistance to preceding therapies caused the emergence of new therapeutic strategies. A promising solution surfaces with a V-domain Ig suppressor of T-cell activation (VISTA), a negative regulator of a T-cell function expressed in hematopoietic cells. Due to VISTA's ability to act as both a ligand and a receptor, several therapeutic approaches can be potentially developed. A broad expression of VISTA was discovered on various tumor-growth-controlling cells, which proved to increase in specific tumor microenvironment (TME) conditions, thus serving as a rationale behind the development of new VISTA-targeting. Nevertheless, VISTA's ligands and signaling pathways are still not fully understood. The uncertain results of clinical trials suggest the need for future examining inhibitor agents for VISTA and implicating a double immunotherapeutic blockade. However, more research is needed before the breakthrough can be achieved. This review discusses perspectives and novel approaches presented in the current literature. Based on the results of the ongoing studies, VISTA might be considered a potential target in combined therapy, especially for treating gastrointestinal malignancies.

Clinical and molecular overview of immunotherapeutic approaches for malignant skin melanoma: Past, present and future

Traditional therapeutic approaches for malignant melanoma, have proved to be limited and/or ineffective, especially with respect to their role in improving patient survival and tumor recurrence. In this regard, immunotherapy has been demonstrated to be a promising therapeutic alternative, boosting antitumor responses through the modulation of cell signaling pathways involved in the effector mechanisms of the immune system, particularly, the so-called "immunological checkpoints". Clinical studies on the efficacy and safety of immunotherapeutic regimens, alone or in combination with other antitumor approaches, have increased dramatically in recent decades, with very encouraging results. Hence, this review will discuss the current immunotherapeutic regimens used to treat malignant melanoma, as well as the molecular and cellular mechanisms involved. In addition, current clinical studies that have investigated the use, efficacy, and adverse events of immunotherapy in melanoma will also be discussed.

The Role of Different Immunocompetent Cell Populations in the Pathogenesis of Head and Neck Cancer-Regulatory Mechanisms of Pro- and Anti-Cancer Activity and Their Impact on Immunotherapy

Head and neck squamous cell carcinoma (HNSCC) is one of the most aggressive and heterogeneous groups of human neoplasms. HNSCC is characterized by high morbidity, accounting for 3% of all cancers, and high mortality with ~1.5% of all cancer deaths. It was the most common cancer worldwide in 2020, according to the latest GLOBOCAN data, representing the seventh most prevalent human malignancy. Despite great advances in surgical techniques and the application of modern combinations and cytotoxic therapies, HNSCC remains a leading cause of death worldwide with a low overall survival rate not exceeding 40-60% of the patient population. The most common causes of death in patients are its frequent nodal metastases and local neoplastic recurrences, as well as the relatively low response to treatment and severe drug resistance. Much evidence suggests that the tumour microenvironment (TME), tumour infiltrating lymphocytes (TILs) and circulating various subpopulations of immunocompetent cells, such regulatory T cells (CD4+CD25+Foxp3+Tregs), cytotoxic CD3+CD8+ T cells (CTLs) and CD3+CD4+ T helper type 1/2/9/17 (Th1/Th2/Th9/Th17) lymphocytes, T follicular helper cells (Tfh) and CD56dim/CD16bright activated natural killer cells (NK), carcinoma-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), tumour-associated neutrophils (N1/N2 TANs), as well as tumour-associated macrophages (M1/M2 phenotype TAMs) can affect initiation, progression and spread of HNSCC and determine the response to immunotherapy. Rapid advances in the field of immuno-oncology and the constantly growing knowledge of the immunosuppressive mechanisms and effects of tumour cancer have allowed for the use of effective and personalized immunotherapy as a first-line therapeutic procedure or an essential component of a combination therapy for primary, relapsed and metastatic HNSCC. This review presents the latest reports and molecular studies regarding the anti-tumour role of selected subpopulations of immunocompetent cells in the pathogenesis of HNSCC, including HPV+ve (HPV+) and HPV-ve (HPV-) tumours. The article focuses on the crucial regulatory mechanisms of pro- and anti-tumour activity, key genetic or epigenetic changes that favour tumour immune escape, and the strategies that the tumour employs to avoid recognition by immunocompetent cells, as well as resistance mechanisms to T and NK cell-based immunotherapy in HNSCC. The present review also provides an overview of the pre- and clinical early trials (I/II phase) and phase-III clinical trials published in this arena, which highlight the unprecedented effectiveness and limitations of immunotherapy in HNSCC, and the emerging issues facing the field of HNSCC immuno-oncology.

Immune checkpoint gene VSIR predicts patient prognosis in acute myeloid leukemia and myelodysplastic syndromes

BACKGROUND

Immune checkpoint proteins play critical functions during the immune response to cancer and have been targeted by immune checkpoint blockade therapy. V-domain Ig suppressor of T cell activation (VSIR) is one of these immune checkpoint genes and has been investigated extensively in recent years due to its conflicting roles in cancer immunity. Specifically, in acute myeloid leukemia (AML), the prognostic value of VSIR is debated.

RESULTS

In both patient tumor samples and cancer cell lines we find that VSIR has the highest expression in AML out of all cancer types and, in AML, has the highest expression out of all other immune checkpoint genes. Survival analysis indicated that AML patients with higher VSIR expression have significantly shorter survival than those patients with lower expression, even within established AML subgroups (e.g., FAB subtypes). Importantly, VSIR expression is predictive of progression from myelodysplastic syndromes (MDS) patients into AML, suggesting its potential role during the very early stage of AML development and progression. In addition to AML, VSIR also demonstrates prognostic values in other cancer types, including multiple myeloma and mesothelioma.

CONCLUSION

In summary, our analyses revealed the prognostic value of VSIR and its potential as a target for immunotherapy, especially in AML.

VISTA H-Score Is Significantly Associated with a 5-Year DFS Rate in Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is the most common type of oral cancer in the world. Despite its prevalence, it is often recognized in advanced stages (III or IV) when it has already spread to local lymph nodes. In this study, we investigate the V-domain Ig suppressor of T cell activation (VISTA) as a potential prognostic factor in OSCC. Tissue samples were collected from 71 oral squamous cell carcinoma patients to determine protein expression levels (using immunochemistry and the semi-quantitative H-score method). Moreover, RT-qPCR was additionally performed in 35 patients. Clinical factors in our cohort study had no impact on VISTA expression. However, VISTA expression is largely correlated with Il-33 levels in tumor cells and lymphocytes and with PD-L1 in tumor cells. The impact of VISTA expression on overall survival (OS) is rather limited, but in the case of a 5-year survival rate, a significant association has been proven. VISTA seems to be a rather weak clinicopathological marker but needs further evaluation in the context of survival. In addition, the potential of VISTA combination with Il-33 or PD-L1 should be further investigated in OSCC.

A PRRX1 Signature Identifies TIM-3 and VISTA as Potential Immune Checkpoint Targets in a Subgroup of Microsatellite Stable Colorectal Cancer Liver Metastases

Disease recurrence and drug resistance are major challenges in the clinical management of patients with colorectal cancer liver metastases (CLM), and because tumors are generally microsatellite stable (MSS), responses to immune therapies are poor. The mesenchymal phenotype is overrepresented in treatment-resistant cancers and is associated with an immunosuppressed microenvironment. The aim of this work was to molecularly identify and characterize a mesenchymal subgroup of MSS CLM to identify novel therapeutic approaches. We here generated a mesenchymal gene expression signature by analysis of resection specimens from 38 patients with CLM using ranked expression level of the epithelial-to-mesenchymal transition-related transcription factor PRRX1. Downstream pathway analysis based on the resulting gene signature was performed and independent, publicly available datasets were used to validate the findings. A subgroup comprising 16% of the analyzed CLM samples were classified as mesenchymal, or belonging to the PRRX1 high group. Analysis of the PRRX1 signature genes revealed a distinct immunosuppressive phenotype with high expression of immune checkpoints HAVCR2/TIM-3 and VISTA, in addition to the M2 macrophage marker CD163. The findings were convincingly validated in datasets from three external CLM cohorts. Upregulation of immune checkpoints HAVCR2/TIM-3 and VISTA in the PRRX1 high subgroup is a novel finding, and suggests immune evasion beyond the PD-1/PD-L1 axis, which may contribute to poor response to PD-1/PD-L1-directed immune therapy in MSS colorectal cancer. Importantly, these checkpoints represent potential novel opportunities for immune-based therapy approaches in a subset of MSS CLM.

Significance

CLM is an important cause of colorectal cancer mortality where the majority of patients have yet to benefit from immunotherapies. In this study of gene expression profiling analyses, we uncovered novel immune checkpoint targets in a subgroup of patients with MSS CLMs harboring a mesenchymal phenotype.

Targeting immune checkpoints in anti-neutrophil cytoplasmic antibodies associated vasculitis: the potential therapeutic targets in the future

Anti-neutrophil cytoplasmic autoantibodies (ANCA) associated vasculitis (AAV) is a necrotizing vasculitis mainly involving small blood vessels. It is demonstrated that T cells are important in the pathogenesis of AAV, including regulatory T cells (Treg) and helper T cells (Th), especially Th2, Th17, and follicular Th cells (Tfh). In addition, the exhaustion of T cells predicted the favorable prognosis of AAV. The immune checkpoints (ICs) consist of a group of co-stimulatory and co-inhibitory molecules expressed on the surface of T cells, which maintains a balance between the activation and exhaustion of T cells. CD28, inducible T-cell co-stimulator (ICOS), OX40, CD40L, glucocorticoid induced tumor necrosis factor receptor (GITR), and CD137 are the common co-stimulatory molecules, while the programmed cell death 1 (PD-1), cytotoxic T lymphocyte-associated molecule 4 (CTLA-4), T cell immunoglobulin (Ig) and mucin domain-containing protein 3 (TIM-3), B and T lymphocyte attenuator (BTLA), V-domain Ig suppressor of T cell activation (VISTA), T-cell Ig and ITIM domain (TIGIT), CD200, and lymphocyte activation gene 3 (LAG-3) belong to co-inhibitory molecules. If this balance was disrupted and the activation of T cells was increased, autoimmune diseases (AIDs) might be induced. Even in the treatment of malignant tumors, activation of T cells by immune checkpoint inhibitors (ICIs) may result in AIDs known as rheumatic immune-related adverse events (Rh-irAEs), suggesting the importance of ICs in AIDs. In this review, we summarized the features of AAV induced by immunotherapy using ICIs in patients with malignant tumors, and then reviewed the biological characteristics of different ICs. Our aim was to explore potential targets in ICs for future treatment of AAV.

Macrophages as a Potential Immunotherapeutic Target in Solid Cancers

The revolution in cancer immunotherapy over the last few decades has resulted in a paradigm shift in the clinical care of cancer. Most of the cancer immunotherapeutic regimens approved so far have relied on modulating the adaptive immune system. In recent years, strategies and approaches targeting the components of innate immunity have become widely recognized for their efficacy in targeting solid cancers. Macrophages are effector cells of the innate immune system, which can play a crucial role in the generation of anti-tumor immunity through their ability to phagocytose cancer cells and present tumor antigens to the cells of adaptive immunity. However, the macrophages that are recruited to the tumor microenvironment predominantly play pro-tumorigenic roles. Several strategies targeting pro-tumorigenic functions and harnessing the anti-tumorigenic properties of macrophages have shown promising results in preclinical studies, and a few of them have also advanced to clinical trials. In this review, we present a comprehensive overview of the pathobiology of TAMs and their role in the progression of solid malignancies. We discuss various mechanisms through which TAMs promote tumor progression, such as inflammation, genomic instability, tumor growth, cancer stem cell formation, angiogenesis, EMT and metastasis, tissue remodeling, and immunosuppression, etc. In addition, we also discuss potential therapeutic strategies for targeting TAMs and explore how macrophages can be used as a tool for next-generation immunotherapy for the treatment of solid malignancies.

Helicobacter pylori Immune Response in Children Versus Adults

H. pylori is perhaps the most prevalent human pathogen worldwide and infects almost half of the world's population. Despite the decreasing prevalence of infection overall, it is significant in developing countries. Most infections are acquired in childhood and persist for a lifetime unless treated. Children are often asymptomatic and often develop a tolerogenic immune response that includes T regulatory cells and their products, immunosuppressive cytokines, such as interleukin (IL)-10, and transforming growth factor-β (TGF-β). This contrasts to the gastric immune response seen in H. pylori-infected adults, where the response is mainly inflammatory, with predominant Th1 and Th17 cells, as well as, inflammatory cytokines, such as TNF-α, IFN-γ, IL-1, IL-6, IL-8, and IL-17. Therefore, compared to adults, infected children generally have limited gastric inflammation and peptic ulcer disease. H. pylori surreptitiously subverts immune defenses to persist in the human gastric mucosa for decades. The chronic infection might result in clinically significant diseases in adults, such as peptic ulcer disease, gastric adenocarcinoma, and mucosa-associated lymphoid tissue lymphoma. This review compares the infection in children and adults and highlights the H. pylori virulence mechanisms responsible for the pathogenesis and immune evasion.

Isolated BAP1 Genomic Alteration in Malignant Pleural Mesothelioma Predicts Distinct Immunogenicity with Implications for Immunotherapeutic Response

Malignant pleural mesothelioma (MPM), an aggressive cancer of the mesothelial cells lining the pleural cavity, lacks effective treatments. Multiple somatic mutations and copy number losses in tumor suppressor genes (TSGs) BAP1, CDKN2A/B, and NF2 are frequently associated with MPM. The impact of single versus multiple genomic alterations of TSG on MPM biology, the immune tumor microenvironment, clinical outcomes, and treatment responses are unknown. Tumors with genomic alterations in BAP1 alone were associated with a longer overall patient survival rate compared to tumors with CDKN2A/B and/or NF2 alterations with or without BAP1 and formed a distinct immunogenic subtype with altered transcription factor and pathway activity patterns. CDKN2A/B genomic alterations consistently contributed to an adverse clinical outcome. Since the genomic alterations of only BAP1 was associated with the PD-1 therapy response signature and higher LAG3 and VISTA gene expression, it might be a candidate marker for immune checkpoint blockade therapy. Our results on the impact of TSG genotypes on MPM and the correlations between TSG alterations and molecular pathways provide a foundation for developing individualized MPM therapies.

Disrupting cancer angiogenesis and immune checkpoint networks for improved tumor immunity

Immune checkpoint inhibitors (ICIs) have advanced the field of cancer immunotherapy in patients by sustaining effector immune cell activity within the tumor microenvironment. However, the approach in general is still faced with issues related to ICI response duration/resistance, treatment eligibility, and safety, which indicates a need for further refinements. As immune checkpoint upregulation is inextricably linked to cancer-induced angiogenesis, newer clinical efforts have demonstrated the feasibility of disrupting both tumor-promoting networks to mediate enhanced immune-driven protection. This review focuses on such key evidence stipulating the necessity of co-applying ICI and anti-angiogenic strategies in cancer patients, with particular interest in highlighting newer engineered antibody approaches that may provide theoretically superior multi-pronged and safe therapeutic combinations.

Immune checkpoint proteins: Signaling mechanisms and molecular interactions in cancer immunotherapy

Immune checkpoint proteins (ICP) are currently one of the most novel and promising areas of immune-oncology research. This novel way of targeting tumor cells has shown favorable success over the past few years with some FDA approvals such as Ipilimumab, Nivolumab, Pembrolizumab etc. Currently, more than 3000 clinical trials of immunotherapeutic agents are ongoing with majority being ICPs. However, as the number of trials increase so do the challenges. Some challenges such as adverse side effects, non-specific binding on healthy tissues and absence of response in some subset populations are critical obstacles. For a safe and effective further therapeutic development of molecules targeting ICPs, understanding their mechanism at molecular level is crucial. Since ICPs are mostly membrane bound receptors, a number of downstream signaling pathways divaricate following ligand-receptor binding. Most ICPs are expressed on more than one type of immune cell populations. Further, the expression varies within a cell type. This naturally varied expression pattern adds to the difficulty of targeting specific effector immune cell types against cancer. Hence, understanding the expression pattern and cellular mechanism helps lay out the possible effect of any immunotherapy. In this review, we discuss the signaling mechanism, expression pattern among various immune cells and molecular interactions derived using interaction database analysis (BioGRID).

The expression of VISTA on CD4+ T cells associate with poor prognosis and immune status in non-small cell lung cancer patients

Besides the two main histologic types of papillary thyroid carcinoma (PTC), the classical PTC (CL-PTC) and the follicular variant PTC (FV-PTC), several other variants are described. The encapsulated FV-PTC variant was recently reclassified as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) due to its similarities to benign lesions. Specific molecular signatures, however, are still unavailable. It is well known that improper DNA repair of dysfunctional telomeres may cause telomere-related genome instability. The mechanisms involved in the damaged telomere repair processing may lead to detrimental outcomes, altering the three-dimensional (3D) nuclear telomere and genome organization in cancer cells. This pilot study aimed to evaluate whether a specific 3D nuclear telomere architecture might characterize NIFTP, potentially distinguishing it from other PTC histologic variants. Our findings demonstrate that 3D telomere profiles of CL-PTC and FV-PTC were different from NIFTP and that NIFTP more closely resembles follicular thyroid adenoma (FTA). NIFTP has longer telomeres than CL-PTC and FV-PTC samples, and the telomere length of NIFTP overlaps with that of the FTA histotype. In contrast, there was no association between BRAF expression and telomere length in all tested samples. These preliminary findings reinforce the view that NIFTP is closer to non-malignant thyroid nodules and confirm that PTC features short telomeres.

Differential expression of checkpoint markers in the normoxic and hypoxic microenvironment of glioblastomas

Glioblastoma is the most common primary malignant brain tumor in adults with an overall survival of only 14.6 months. Hypoxia is known to play a role in tumor aggressiveness but the influence of hypoxia on the immune microenvironment is not fully understood. The aim of this study was to investigate the expression of immune-related proteins in normoxic and hypoxic tumor areas by digital spatial profiling. Tissue samples from 10 glioblastomas were stained with a panel of 40 antibodies conjugated to photo-cleavable oligonucleotides. The free oligo-tags from normoxic and hypoxic areas were hybridized to barcodes for digital counting. Differential expression patterns were validated by Ivy Glioblastoma Atlas Project (GAP) data and an independent patient cohort. We found that CD44, Beta-catenin and B7-H3 were upregulated in hypoxia, whereas VISTA, CD56, KI-67, CD68 and CD11c were downregulated. PD-L1 and PD-1 were not affected by hypoxia. Focusing on the checkpoint-related markers CD44, B7-H3 and VISTA, our findings for CD44 and VISTA could be confirmed with Ivy GAP RNA sequencing data. Immunohistochemical staining and digital quantification of CD44, B7-H3 and VISTA in an independent cohort confirmed our findings for all three markers. Additional stainings revealed fewer T cells and high but equal amounts of tumor-associated microglia and macrophages in both hypoxic and normoxic regions. In conclusion, we found that CD44 and B7-H3 were upregulated in areas with hypoxia whereas VISTA was downregulated together with the presence of fewer T cells. This heterogeneous expression should be taken into consideration when developing novel therapeutic strategies.

Emerging immune checkpoint inhibitors for the treatment of non-small cell lung cancer

INTRODUCTION

Over the last decade, immune checkpoint inhibitors (ICIs) have impacted on the standard therapy for patients with non-small cell lung cancer (NSCLC). ICIs first showed efficacy in patients with advanced disease who had progressed after chemotherapy, later reaching the first-line therapy context alone, in combination with chemotherapy, and/or with dual-immunotherapy regimens.

AREAS COVERED

Most of their benefit is, however, restricted to just 20% of patients due to primary or emergence of acquired resistance. In this review, we will describe the role of new emerging ICIs in the current panorama of NSCLC therapeutic approaches, not only in metastatic disease but also in locally advanced stage disease, with specific focus on those drugs under investigation in Phase 2/3 clinical trials.

EXPERT OPINION

Several new ICIs are now under investigation to optimize NSCLC patient management; these are usually used in combination with other well-known agents, such as 'traditional' ICIs and chemotherapy, or with other newly developed drugs. Identification of better biomarkers will provide personalized treatment approaches to overcome patient-specific immune resistance.

The Cellular and Molecular Immunotherapy in Prostate Cancer

In recent history, immunotherapy has become a viable cancer therapeutic option. However, over many years, its tenets have changed, and it now comprises a range of cancer-focused immunotherapies. Clinical trials are currently looking into monotherapies or combinations of medicines that include immune checkpoint inhibitors (ICI), CART cells, DNA vaccines targeting viruses, and adoptive cellular therapy. According to ongoing studies, the discipline should progress by incorporating patient-tailored immunotherapy, immune checkpoint blockers, other immunotherapeutic medications, hormone therapy, radiotherapy, and chemotherapy. Despite significantly increasing morbidity, immunotherapy can intensify the therapeutic effect and enhance immune responses. The findings for the immunotherapy treatment of advanced prostate cancer (PCa) are compiled in this study, showing that is possible to investigate the current state of immunotherapy, covering new findings, PCa treatment techniques, and research perspectives in the field’s unceasing evolution.

Immune checkpoint modulators in cancer immunotherapy: recent advances and emerging concepts

The discovery of immune checkpoint inhibitors (ICIs) has now been universally acknowledged as a significant breakthrough in tumor therapy after the targeted treatment of checkpoint molecules: anti-programmed cell death protein 1/programmed cell death ligand 1 (PD-1/PD-L1) and anti-cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) on several cancer types achieved satisfying results. However, there are still quite a lot of patients suffering from severe side effects and ineffective treatment outcomes. Although the current ICI therapy is far from satisfying, a series of novel immune checkpoint molecules with remarkable preclinical and clinical benefits are being widely investigated, like the V-domain Ig suppressor of T cell activation (VISTA), which can also be called PD-1 homolog (PD-1H), and ectonucleotidases: CD39, CD73, and CD38, which belong to the ribosyl cyclase family, etc. In this review, we systematically summarized and discussed these molecules' biological structures, molecular features, and the corresponding targeted drugs, aiming to help the in-depth understanding of immune checkpoint molecules and promote the clinical practice of ICI therapy.

Immune checkpoint modulators in cancer immunotherapy: recent advances and emerging concepts

The discovery of immune checkpoint inhibitors (ICIs) has now been universally acknowledged as a significant breakthrough in tumor therapy after the targeted treatment of checkpoint molecules: anti-programmed cell death protein 1/programmed cell death ligand 1 (PD-1/PD-L1) and anti-cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) on several cancer types achieved satisfying results. However, there are still quite a lot of patients suffering from severe side effects and ineffective treatment outcomes. Although the current ICI therapy is far from satisfying, a series of novel immune checkpoint molecules with remarkable preclinical and clinical benefits are being widely investigated, like the V-domain Ig suppressor of T cell activation (VISTA), which can also be called PD-1 homolog (PD-1H), and ectonucleotidases: CD39, CD73, and CD38, which belong to the ribosyl cyclase family, etc. In this review, we systematically summarized and discussed these molecules' biological structures, molecular features, and the corresponding targeted drugs, aiming to help the in-depth understanding of immune checkpoint molecules and promote the clinical practice of ICI therapy.

Establishment of a Monoclonal Antibody-Based Enzyme-Linked Immunosorbent Assay to Measure Soluble B7-H5 in Patients with Cancer

B7-H5, an immune checkpoint molecule, is markedly upregulated in multiple cancers and plays an important role in tumor progression and immune escape. However, the expression and significance of soluble B7-H5 (sB7-H5) in cancer remain unclear. Herein, we generated two novel mouse anti-human B7-H5 monoclonal antibodies (mAbs) 2E5 and 7B10, which had different epitopes. Based on the two mAbs, a sandwich enzyme-linked immunosorbent assay (ELISA) system was developed. Using this ELISA, we found that compared with healthy controls (HCs), sB7-H5 levels were significantly increased in the serum of patients with gastric cancer (GC), colorectal cancer (CRC), and lung cancer (LC) and were associated with TNM stage and metastasis. Receiver operating characteristic (ROC) curve analysis showed that sB7-H5 has diagnostic value for GC, CRC, and LC. Collectively, our findings delineate that sB7-H5 may be used as a predictor for diagnosis of cancer and a potential therapeutic target for cancer treatment.

Immune Checkpoint Inhibitors in Cancer Therapy—How to Overcome Drug Resistance?

Simple Summary

Immune checkpoint inhibitors (ICIs) are an important strategy in cancer therapy. However, with the widespread clinical use of ICIs, people gradually found that ICIs may not be effective enough to eliminate tumor tissue for certain patients. The resistance to ICI treatment makes some patients unable to benefit from their antitumor effects. Therefore, it is vital to understand their antitumor and drug resistance mechanisms to better narrow the ICI-resistant patient population. This review outlines the antitumor action sites and mechanisms of different types of ICIs and lists the main reason of ICI resistance based on recent studies. Finally, we propose current and future solutions for resistance to ICIs.

Abstract

Immune checkpoint inhibitors (ICIs), antagonists used to remove tumor suppression of immune cells, have been widely used in clinical settings. Their high antitumor effect makes them crucial for treating cancer after surgery, radiotherapy, chemotherapy, and targeted therapy. However, with the advent of ICIs and their use by a large number of patients, more clinical data have gradually shown that some cancer patients still have resistance to ICI treatment, which makes some patients unable to benefit from their antitumor effect. Therefore, it is vital to understand their antitumor and drug resistance mechanisms. In this review, we focused on the antitumor action sites and mechanisms of different types of ICIs. We then listed the main possible mechanisms of ICI resistance based on recent studies. Finally, we proposed current and future solutions for the resistance of ICIs, providing theoretical support for improving their clinical antitumor effect.

IGSF11 and VISTA: a pair of promising immune checkpoints in tumor immunotherapy

Immunotherapy has become the major treatment for tumors in clinical practice, but some intractable problems such as the low response rate and high rates of immune-related adverse events still hinder the progress of tumor immunotherapy. Hence, it is essential to explore additional immunotherapy treatment targets. In this review, we focus on the structure, expression and expression-related mechanisms, interactions, biological functions and the progress in preclinical/clinical research of IGSF11 and VISTA in tumors. We cover the progress in recent research with this pair of immune checkpoints in tumor immune regulation, proliferation, immune resistance and predictive prognosis. Both IGSF11 and VISTA are highly expressed in tumors and are modulated by various factors. They co-participate in the functional regulation of immune cells and the inhibition of cytokine production. Besides, in the downregulation of IGSF11 and VISTA, both inhibit the growth of some tumors. Preclinical and clinical trials all emphasize the predictive role of IGSF11 and VISTA in the prognosis of tumors, and that the predictive role of the same gene varies from tumor to tumor. At present, further research is proving the enormous potential of IGSF11 and VISTA in tumors, and especially the role of VISTA in tumor immune resistance. This may prove to be a breakthrough to solve the current clinical immune resistance, and most importantly, since research has focused on VISTA but less on IGSF11, IGSF11 may be the next candidate for tumor immunotherapy.