DNAM-1 versus TIGIT: competitive roles in tumor immunity and inflammatory responses

A novel enzyme-linked immunosorbent assay tool to evaluate plasma soluble CD226 in primary Sjögren's syndrome

CD226 is an important receptor constitutively expressed on most immune cells, performing vital functions in immune responses. However, the levels of soluble CD226 (sCD226) and its roles in primary Sjögren syndrome (pSS) remain unclear. In this study, we developed two novel mouse anti-human CD226 monoclonal antibodies (mAbs) and established a novel sandwich enzyme-linked immunosorbent assay (ELISA) system, which proved to be highly effective in detecting human sCD226. We then analyzed the expression of sCD226 in the plasma of pSS patients. Our results showed that the levels of sCD226 were significantly lower in patients with pSS compared to healthy controls. The significant decline was also observed in active group and the patients with high levels of IgG or positive anti-SSB. Additionally, reduced sCD226 was found to be negatively correlated with the disease activity of pSS and several clinical manifestations, including arthralgia, fatigue, decayed tooth and interstitial lung disease (ILD). Furthermore, receiver operator characteristics (ROC) curve analysis showed that sCD226 displayed outstanding capacity in discriminating pSS and predicting the disease activity. Altogether, plasma sCD226 emerges as a promising candidate for diagnostic markers in the context of pSS.

Costimulatory Molecule CD226 Regulates Atopic Dermatitis in a Mouse Model

This study investigated the role of CD226 in a 2,4-dinitrochlorobenzene (DNCB)-induced mouse model of atopic dermatitis. The results showed that the lack of CD226 (global and CD4+ T-cell specific) significantly increased ear thickness, reddening, swelling, and scaling of the skin as well as inflammatory cell and mast cell infiltration. RT-qPCR results demonstrated that the mRNA expressions of atopic dermatitis-related inflammatory cytokines and chemokines were markedly increased in the draining lymph nodes and lesioned ear skin tissues of global and CD4+ T-cell-specific CD226-deficient mice compared with that in control mice. In vitro assessment revealed that CD226 directly modulates TGFβ-mediated regulatory T (Treg) cell differentiation and proliferation. Notably, Treg cell-specific deletion of CD226 (Cd226fl/flFoxp3cre mice) resulted in more severe dermatitis and epidermal thickening than those observed in littermate mice upon DNCB treatment. Subsequent analysis showed that the infiltration of Treg cells in ear lesions and the number of Tregs in the spleen were significantly reduced in Cd226fl/flFoxp3cre mice after DNCB treatment. In addition, the lack of CD226 induced apoptosis of Treg cells through the activation of caspase 3. Therefore, these results suggest that CD226 has potential efficacy in atopic dermatitis, correlating with Treg cell inhibition.

Cataloging circulating CD3+CD56+ NKT-like cells through a series of stimulating (NKG2D and DNAM-1) and inhibitory (PD-1, TIGIT, and Tim-3) immune checkpoint receptors in women diagnosed with precancerous cervical lesions or invasive cervical carcinoma

Persistent human papillomavirus infection is associated with the development of premalignant lesions that can eventually lead to cervical cancer. In this study, we evaluated the expression of activating (NKG2D, DNAM-1) and inhibitory immune checkpoints receptors (PD-1, TIGIT, and Tim-3) in peripheral blood NKT-like (CD3+CD56+) lymphocytes from patients with cervical carcinoma (CC, n = 19), high-grade lesions (HG, n = 8), low-grade lesions (LG, n = 19) and healthy donors (HD, n = 17) using multiparametric flow cytometry. Dimensional data analysis showed four clusters within the CD3+CD56+ cells with different patterns of receptor expression. We observed upregulation of CD16 in CC and HG patients in one of the clusters. In another, TIGIT was upregulated, while DNAM-1 was downregulated. Throughout manual gating, we observed that NKT-like cells expressing activating receptors also co-express inhibitory receptors (PD-1 and TIGIT), which can affect the activation of these cells. A deeper characterization of the functional state of the cells may help to clarify their role in cervical cancer, as will the characterization of the NKT-like cells as cytotoxic CD8+ T cells or members of type I or type II NKT cells.

Immune restoration by TIGIT blockade is insufficient to control chronic SIV infection

TIGIT is a negative immune checkpoint receptor associated with T cell exhaustion in cancer and HIV. TIGIT upregulation in virus-specific CD8+ T cells and NK cells during HIV/SIV infection results in dysfunctional effector capabilities. In vitro studies targeting TIGIT on CD8+ T cells suggest TIGIT blockade as a viable strategy to restore SIV-specific T cell responses. Here, we extend these studies in vivo using TIGIT blockage in nonhuman primates in an effort to reverse T cell and NK cell exhaustion in the setting of SIV infection. We demonstrate that in vivo administration of a humanized anti-TIGIT monoclonal antibody (mAb) is well tolerated in both cynomolgus macaques and rhesus macaques. Despite sustained plasma concentrations of anti-TIGIT mAb, we observed no consistent improvement in NK or T cell cytolytic capacity. TIGIT blockade minimally enhanced T cell proliferation and virus-specific T cell responses in both magnitude and breadth though plasma viral loads in treated animals remained stable indicating that anti-TIGIT mAb treatment alone was insufficient to increase anti-SIV CD8+ T cell function. The enhancement of virus-specific T cell proliferative responses observed in vitro with single or dual blockade of TIGIT and/or PD-1 highlights TIGIT as a potential target to reverse T cell dysfunction. Our studies, however, reveal that targeting the TIGIT pathway alone may be insufficient in the setting of viremia and that combining immune checkpoint blockade with other immunotherapeutics may be a future path forward for improved viral control or elimination of HIV.IMPORTANCEUpregulation of the immune checkpoint receptor TIGIT is associated with HIV-mediated T cell dysfunction and correlates with HIV disease progression. Compelling evidence exists for targeting immune checkpoint receptor pathways that would potentially enhance immunity and refocus effector cell efforts toward viral clearance. In this report, we investigate TIGIT blockade as an immunotherapeutic approach to reverse immune exhaustion during chronic SIV/SHIV infection in a nonhuman primate model of HIV infection. We show that interfering with the TIGIT signaling axis alone is insufficient to improve viral control despite modest improvement in T cell immunity. Our data substantiate the use of targeting multiple immune checkpoint receptors to promote synergy and ultimately eliminate HIV-infected cells.

TIGIT Regulates T Cell Inflammation in Airway Inflammatory Diseases

TIGIT, a co-inhibitory receptor found on T cells and NK cells, transmits inhibitory signals upon binding to its ligand. This interaction suppresses the activation of various signaling pathways, leading to functional exhaustion of cells, ultimately dampening excessive inflammatory responses or facilitating immune evasion in tumors. Dysregulated TIGIT expression has been noted in T cells across different inflammatory conditions, exhibiting varying effects based on T cell subsets. TIGIT predominantly restrains the effector function of pro-inflammatory T cells, upholds the suppressive function of regulatory T cells, and influences Tfh maturation. Mechanistically, the IL27-induced transcription factors c-Maf and Blimp-1 are believed to be key regulators of TIGIT expression in T cells. Notably, TIGIT expression in T cells is implicated in lung diseases, particularly airway inflammatory conditions such as lung cancer, obstructive pulmonary disease, interstitial lung disease, sarcoidosis, and COVID-19. This review emphasizes the significance of TIGIT in the context of T cell immunity and airway inflammatory diseases.

Unleashing the power of immune checkpoints: Post-translational modification of novel molecules and clinical applications

Immune checkpoint molecules play a pivotal role in the initiation, regulation, and termination of immune responses. Tumor cells exploit these checkpoints to dampen immune cell function, facilitating immune evasion. Clinical interventions target this mechanism by obstructing the binding of immune checkpoints to their ligands, thereby restoring the anti-tumor capabilities of immune cells. Notably, therapies centered on immune checkpoint inhibitors, particularly PD-1/PD-L1 and CTLA-4 blocking antibodies, have demonstrated significant clinical promise. However, a considerable portion of patients still encounter suboptimal efficacy and develop resistance. Recent years have witnessed an exponential surge in preclinical and clinical trials investigating novel immune checkpoint molecules such as TIM3, LAG3, TIGIT, NKG2D, and CD47, along with their respective ligands. The processes governing immune checkpoint molecules, from their synthesis to transmembrane deployment, interaction with ligands, and eventual degradation, are intricately tied to post-translational modifications. These modifications encompass glycosylation, phosphorylation, ubiquitination, neddylation, SUMOylation, palmitoylation, and ectodomain shedding. This discussion proceeds to provide a concise overview of the structural characteristics of several novel immune checkpoints and their ligands. Additionally, it outlines the regulatory mechanisms governed by post-translational modifications, offering insights into their potential clinical applications in immune checkpoint blockade.

Simulated microgravity increases CD226+ Lin- CD117- Sca1+ mesenchymal stem cells in mice

Microgravity is one of the most common causes counting for the bone loss. Mesenchymal stem cells (MSCs) contribute greatly to the differentiation and function of bone related cells. The development of novel MSCs biomarkers is critical for implementing effective therapies for microgravity induced bone loss. We aimed to find the new molecules involved in the differentiation and function of MSCs in mouse simulated microgravity model. We found CD226 was preferentially expressed on a subset of MSCs. Simulation of microgravity treatment significantly increased the proportion of CD226+ Lin- CD117- Sca1+ MSCs. The CD226+ MSCs produced higher IL-6, M-CSF, RANKL and lower CD200 expression, and promoted osteoclast differentiation. This study provides pivotal information to understand the role of CD226 in MSCs, and inspires new ideas for prevention of bone loss related diseases.

TIGIT: A potential immunotherapy target for gynecological cancers

Gynecological cancer represents a significant global health challenge, and conventional treatment modalities have demonstrated limited efficacy. However, recent investigations into immune checkpoint pathways have unveiled promising opportunities for enhancing the prognosis of patients with cancer. Among these pathways, TIGIT has surfaced as a compelling candidate owing to its capacity to augment the immune function of NK and T cells through blockade, thereby yielding improved anti-tumor effects and prolonged patient survival. Global clinical trials exploring TIGIT blockade therapy have yielded promising preliminary findings. Nevertheless, further research is imperative to comprehensively grasp the potential of TIGIT-based immunotherapy in optimizing therapeutic outcomes for gynecological cancers. This review primarily delineates the regulatory network and immunosuppressive mechanism of TIGIT, expounds upon its expression and therapeutic potential in three major gynecological cancers, and synthesizes the clinical trials of TIGIT-based cancer immunotherapy. Such insights aim to furnish novel perspectives and serve as reference points for subsequent research and clinical application targeting TIGIT in gynecological cancers.

The immune checkpoint TIGIT/CD155 promotes the exhaustion of CD8 + T cells in TNBC through glucose metabolic reprogramming mediated by PI3K/AKT/mTOR signaling

OBJECTIVE

The CD155/TIGIT axis has attracted considerable interest as an emerging immune checkpoint with potential applications in cancer immunotherapy. Our research focused on investigating the role of CD155/TIGIT checkpoints in the progression of triple-negative breast cancer (TNBC).

METHODS

We evaluated CD155 and TIGIT expression in TNBC tissues using both immunohistochemistry (IHC) and gene expression profiling. Our experiments, both in vivo and in vitro, provided evidence that inhibiting the CD155/TIGIT pathway reinstates the ability of CD8 + T cells to generate cytokines. To assess the impact of CD155/TIGIT signaling blockade, we utilized Glucose Assay Kits and Lactate Assay Kits to measure alterations in glucose and lactate levels within CD8 + T cells. We employed western blotting (WB) to investigate alterations in glycolytic-related proteins within the PI3K/AKT/mTOR pathways following the inhibition of CD155/TIGIT signaling.

RESULTS

CD155 exhibits heightened expression within TNBC tissues and exhibits a negative correlation with the extent of infiltrating CD8 + T cells. Furthermore, patients with TNBC demonstrate elevated levels of TIGIT expression. Our findings indicate that the interaction between CD155 and TIGIT disrupts the glucose metabolism of CD8 + T cells by suppressing the activation of the PI3K/AKT/mTOR signaling pathway, ultimately leading to the reduced production of cytokines by CD8 + T cells. Both in vivo and in vitro experiments have conclusively demonstrated that the inhibition of CD155/TIGIT interaction reinstates the capacity of CD8 + T cells to generate cytokines. Moreover, in vivo administration of the blocking antibody against TIGIT not only inhibits tumor growth but also augments the functionality of CD8 + T lymphocytes.

CONCLUSIONS

Our research findings strongly suggest that CD155/TIGIT represents a promising therapeutic target for treating TNBC.

Single-Cell RNA-Sequencing Reveals Peripheral T Helper Cells Promoting the Development of IgG4-Related Disease by Enhancing B Cell Activation and Differentiation

Abnormal B cell differentiation plays a critical role in IgG4-related disease (IgG4-RD), but the underlying mechanism remains largely unknown. We investigated the cell landscape from three IgG4-RD retroperitoneal tissues and three control tissues using single-cell RNA-sequencing. Critical cell type or markers were further validated in the peripheral blood from the patients with IgG4-RD and healthy controls via flow cytometry as well as in the IgG4-RD and control tissue via immunofluorescence staining. The increases in B cells, plasma cells, and CD4+ T cells were found in IgG4-RD retroperitoneal tissue. Importantly, among CD4+ T cells, an increase in CD4+CXCR5-PD1hi peripheral T helper (Tph) cells with a high expression of IL-21 and TIGIT was discovered in IgG4-RD tissue, which was further validated in peripheral blood of the patients with IgG4-RD. The Tph cell and TIGIT+ Tph cell proportion were remarkably higher in active IgG4-RD patients and correlated with disease activity. Moreover, TIGIT+CD4+ cells were able to promote B cell differentiation via IL-21. Our study revealed that Tph cells are increased in IgG4-RD and probably play critical roles in B cell differentiation through TIGIT-IL-21 axis. Peripheral Tph cell and TIGIT+Tph cell are potential markers for IgG4-RD disease activity.

TIGIT, a novel immune checkpoint therapy for melanoma

Melanoma is the most aggressive and deadliest type of skin cancer. In the last 10 years, immune checkpoint blockades (ICBs) including PD-1/PD-L1 and CTLA-4 inhibitor has been shown to be effective against melanoma. PD-1/PD-L1 and CTLA-4 inhibitors have shown varying degrees of drug resistance in the treatment of melanoma patients. Furthermore, the clinical benefits of ICBs are also accompanied by severe immune toxicity. Therefore, there is an urgent need to develop new immune checkpoint inhibitors to optimize melanoma therapy and reduce cytotoxicity. T-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibition motif domain (TIGIT) is thought to activate inhibitory receptors in T cells, natural killer (NK) cells, and regulatory T cells (Tregs), and has become a promising target for immunotherapy. Studies have found that TIGIT can be detected in different stages of melanoma, which is closely related to the occurrence, development, and prognosis of melanoma. This review mainly describes the immunosuppressive mechanism of TIGIT and its role in antitumor immunity of melanoma, so as to provide new ideas and schemes for the clinical treatment of melanoma with targeted TIGIT.

Largely preserved functionality after the combined loss of NKG2D, NCR1 and CD16 demonstrates the remarkable plasticity of NK cell responsiveness

Natural killer (NK) cells play an important role in the early defense against tumors and virally infected cells. Their function is thought to be controlled by the balance between activating and inhibitory receptors, which often compete for the same ligands. Several activating receptors expressed on virtually all NK cells lack an inhibitory partner, most notably CD16, NCR1 and NKG2D. We therefore hypothesized that a signal through at least one of these receptors is always required for full NK cell activation. We generated animals lacking all three receptors (TKO) and analyzed their NK cells. In vitro, TKO NK cells did not show reduced ability to kill tumor targets but displayed hyperresponsiveness to NK1.1 stimulation. In vivo, TKO animals had a minor reduction in their ability to control non-hematopoietic tumors and cytomegalovirus infection, which was the result of reduced NK cell activity. Together, our findings show that activating NK cell receptors without an inhibitory partner do not provide a 'master' signal but are integrated in the cumulative balance of activating and inhibitory signals. Their activity is controlled through regulation of the responsiveness and expression of other activating receptors. Our findings may be important for future development of NK cell-based cancer immunotherapy.

CAR-NK cell therapy for glioblastoma: what to do next?

Glioblastoma is a malignant tumor with the highest morbidity and mortality in the central nervous system. Conventional surgical resection combined with radiotherapy or chemotherapy has a high recurrence rate and poor prognosis. The 5-year survival rate of patients is less than 10%. In tumor immunotherapy, CAR-T cell therapy represented by chimeric antigen receptor-modified T cells has achieved great success in hematological tumors. However, the application of CAR-T cells in solid tumors such as glioblastoma still faces many challenges. CAR-NK cells are another potential adoptive cell therapy strategy after CAR-T cells. Compared with CAR-T cell therapy, CAR-NK cells have similar anti-tumor effects. CAR-NK cells can also avoid some deficiencies in CAR-T cell therapy, a research hotspot in tumor immunity. This article summarizes the preclinical research status of CAR-NK cells in glioblastoma and the problems and challenges faced by CAR-NK in glioblastoma.

Immune Response and Immune Checkpoint Molecules in Patients with Rectal Cancer Undergoing Neoadjuvant Chemoradiotherapy: A Review

It is well-established that tumor antigens and molecules expressed and secreted by cancer cells trigger innate and adaptive immune responses. These two types of anti-tumor immunity lead to the infiltration of the tumor's microenvironment by immune cells with either regulatory or cytotoxic properties. Whether this response is associated with tumor eradication after radiotherapy and chemotherapy or regrowth has been a matter of extensive research through the years, mainly focusing on tumor-infiltrating lymphocytes and monocytes and their subtypes, and the expression of immune checkpoint and other immune-related molecules by both immune and cancer cells in the tumor microenvironment. A literature search has been conducted on studies dealing with the immune response in patients with rectal cancer treated with neoadjuvant radiotherapy or chemoradiotherapy, assessing its impact on locoregional control and survival and underlying the potential role of immunotherapy in the treatment of this cancer subtype. Here, we provide an overview of the interactions between local/systemic anti-tumor immunity, cancer-related immune checkpoint, and other immunological pathways and radiotherapy, and how these affect the prognosis of rectal cancer patients. Chemoradiotherapy induces critical immunological changes in the tumor microenvironment and cancer cells that can be exploited for therapeutic interventions in rectal cancer.

Ablation of CD226 on CD4+ T cells modulates asthma progress associated with altered IL-10 response and gut microbiota

To investigate the role of the costimulatory molecule CD226 in asthma pathogenesis, we produced a CD4⁺ T-cell-specific CD226 knockout mice model (Cd226^ΔCD4) and induced airway allergic inflammation by administering ovalbumin (OVA). Our results revealed alleviated lung inflammation, decreased levels of OVA-specific IgE, and increased levels of IL-10 in the serum of Cd226^ΔCD4 mice (P < 0.05). Moreover, IL-10 levels in CD4⁺ T cells were significantly elevated in the mediastinal lymph node, spleen, and Peyer's patches in the Cd226^ΔCD4 mice compared with those in controls (P < 0.05 to P < 0.01). Notably, there was a significantly higher IL-10 mRNA levels in the large intestine of the mice (P < 0.05). The protective effect of CD226 deficiency is also associated with the accumulation of gut TCRγδ⁺ intraepithelial lymphocytes and reversion of the gut microbiome dysbiosis. The Bacteroidetes-to-Firmicutes ratio and the abundance of Akkermansia increased in the absence of CD226 after OVA treatment. Our data reveal the synchronous changes in the lung and intestine in OVA-treated CD226-knockout mice, supporting the gut-lung axis concept and providing evidence for novel therapeutic approaches for asthma.

TIGIT in Lung Cancer: Potential Theranostic Implications

TIGIT (T cell immunoreceptor with Ig and ITIM domains) is a co-inhibitory receptor expressed on various immune cells, including T cells, NK cells, and dendritic cells. TIGIT interacts with different ligands, such as CD155 and CD112, which are highly expressed on cancer cells, leading to the suppression of immune responses. Recent studies have highlighted the importance of TIGIT in regulating immune cell function in the tumor microenvironment and its role as a potential therapeutic target, especially in the field of lung cancer. However, the role of TIGIT in cancer development and progression remains controversial, particularly regarding the relevance of its expression both in the tumor microenvironment and on tumor cells, with prognostic and predictive implications that remain to date essentially undisclosed. Here, we provide a review of the recent advances in TIGIT-blockade in lung cancer, and also insights on TIGIT relevance as an immunohistochemical biomarker and its possible theranostic implications.

Nectin2 influences cell apoptosis by regulating ANXA2 expression in neuroblastoma

Neuroblastoma (NB) is a pediatric cancer of the peripheral sympathetic nervous system and represents the most frequent solid malignancy in infants. Nectin2 belongs to the immunoglobulin superfamily and has been shown to play a role in tumorigenesis. In the current study, we demonstrate that serum Nectin2 level is increased in NB patients compared with that in healthy controls and Nectin2 level is correlated with neuroblastoma international neuroblastoma staging system (INSS) classification. There is a positive correlation between Nectin2 level and shorter overall survival in NB patients. Knockdown of Nectin2 reduces the migration of SH-SY5Y and SK-N-BE2 cells and induces their apoptosis and cell cycle arrest. RNA-seq analysis demonstrates that Nectin2 knockdown affects the expressions of 258 genes, including 240 that are upregulated and 18 that are downregulated compared with negative controls. qRT-PCR and western blot analysis confirm that ANXA2 expression is decreased in Nectin2-knockdown SH-SY5Y cells, consistent with the RNA-seq results. ANXA2 overexpression rescues the percentage of apoptotic NB cells induced by Nectin2 knockdown and compensates for the impact of Nectin2 knockdown on cleaved caspase3 and bax expressions. In addition, western blot analysis results show that ANXA2 overexpression rescues the effect of Nectin2 knockdown on MMP2 and MMP9 expressions. The current data highlight the importance of Nectin2 in NB progression and the potential of Nectin2 as a novel candidate target for gene therapy.

The Role of NK Cells in EBV Infection and Related Diseases: Current Understanding and Hints for Novel Therapies

The Epstein-Barr virus (EBV) is a ubiquitous herpesvirus most often transmitted during infancy and infecting the vast majority of human beings. Usually, EBV infection is nearly asymptomatic and results in life-long persistency of the virus in a latent state under the control of the host immune system. Yet EBV can cause an acute infectious mononucleosis (IM), particularly in adolescents, and is associated with several malignancies and severe diseases that pose a serious threat to individuals with specific inborn error of immunity (IEI). While there is a general consensus on the requirement for functional CD8 T cells to control EBV infection, the role of the natural killer (NK) cells of the innate arm of immunity is more enigmatic. Here we provide an overview of the interaction between EBV and NK cells in the immunocompetent host as well as in the context of primary and secondary immunodeficiencies. Moreover, we report in vitro data on the mechanisms that regulate the capacity of NK cells to recognize and kill EBV-infected cell targets and discuss the potential of recently optimized NK cell-based immunotherapies for the treatment of EBV-associated diseases.

Extracellular CIRP Induces Novel Nectin-2+ (CD112+) Neutrophils to Promote Th1 Differentiation in Sepsis

Neutrophil heterogeneity represents different subtypes, states, phenotypes, and functionality of neutrophils implicated in sepsis pathobiology. Extracellular cold-inducible RNA-binding protein (eCIRP) is a damage-associated molecular pattern that promotes inflammation and alters neutrophil phenotype and function through TLR4. Nectin-2 or CD112 is an Ig-like superfamily member. CD112 serves as the ligand for DNAM-1 (CD226), which induces Th1 differentiation in naive CD4+ T cells. Th1 cells produce IFN-γ to fuel inflammation. CD112 is expressed mainly on APCs, but its expression in neutrophils is unknown. We hypothesize that eCIRP induces CD112 expression in neutrophils, promoting Th1 differentiation in sepsis. Incubation of neutrophils with recombinant murine (rm)CIRP significantly increased the gene and protein expression of CD112 in neutrophils. Anti-TLR4 Ab-treated neutrophils significantly decreased CD112+ neutrophils compared with controls upon rmCIRP stimulation. After 4 h of rmCIRP injection in mice, CD112+ neutrophils were significantly increased in the blood and spleen. At 20 h after cecal ligation and puncture-induced sepsis, CD112+ neutrophils were also significantly increased. Blood and splenic CD112+ neutrophils in septic CIRP-/- mice were much lower than in septic wild-type mice. Coculture of naive CD4 T cells with rmCIRP-treated (CD112+) neutrophils significantly increased IFN-γ-producing Th1 cells compared with coculture with PBS-treated neutrophils. CD112 Ab significantly attenuated Th1 differentiation induced by rmCIRP-treated neutrophils. Thus, eCIRP increases CD112 expression in neutrophils via TLR4 to promote Th1 differentiation in sepsis. Targeting eCIRP may attenuate sepsis by reducing Th1-promoting CD112+ neutrophils.

Mass cytometry identifies characteristic immune cell subsets in bronchoalveolar lavage fluid from interstitial lung diseases

Immune cells have been implicated in interstitial lung diseases (ILDs), although their phenotypes and effector mechanisms remain poorly understood. To better understand these cells, we conducted an exploratory mass cytometry analysis of immune cell subsets in bronchoalveolar lavage fluid (BALF) from patients with idiopathic pulmonary fibrosis (IPF), connective-tissue disease (CTD)-related ILD, and sarcoidosis, using two panels including 64 markers. Among myeloid cells, we observed the expansion of CD14⁺ CD36^hi CD84^hiCCR2^- monocyte populations in IPF. These CD14⁺ CD36^hi CD84^hi CCR2^- subsets were also increased in ILDs with a progressive phenotype, particularly in a case of acute exacerbation (AEx) of IPF. Analysis of B cells revealed the presence of cells at various stages of differentiation in BALF, with a higher percentage of IgG memory B cells in CTD-ILDs and a trend toward more FCRL5⁺ B cells. These FCRL5⁺ B cells were also present in the patient with AEx-IPF and sarcoidosis with advanced lung lesions. Among T cells, we found increased levels of IL-2R⁺ TIGIT⁺ LAG3⁺ CD4⁺ T cells in IPF, increased levels of CXCR3⁺ CD226⁺ CD4⁺ T cells in sarcoidosis, and increased levels of PD1⁺ TIGIT⁺ CD57⁺ CD8⁺ T cells in CTD-ILDs. Together, these findings underscore the diverse immunopathogenesis of ILDs.

Multiparametric flow cytometry to characterize vaccine-induced polyfunctional T cell responses and T cell/NK cell exhaustion and memory phenotypes in mouse immuno-oncology models

Suitable methods to assess in vivo immunogenicity and therapeutic efficacy of cancer vaccines in preclinical cancer models are critical to overcome current limitations of cancer vaccines and enhance the clinical applicability of this promising immunotherapeutic strategy. In particular, availability of methods allowing the characterization of T cell responses to endogenous tumor antigens is required to assess vaccine potency and improve the antigen formulation. Moreover, multiparametric assays to deeply characterize tumor-induced and therapy-induced immune modulation are relevant to design mechanism-based combination immunotherapies. Here we describe a versatile multiparametric flow cytometry method to assess the polyfunctionality of tumor antigen-specific CD4⁺ and CD8⁺ T cell responses based on their production of multiple cytokines after short-term ex vivo restimulation with relevant tumor epitopes of the most common mouse strains. We also report the development and application of two 21-color flow cytometry panels allowing a comprehensive characterization of T cell and natural killer cell exhaustion and memory phenotypes in mice with a particular focus on preclinical cancer models.

The Dual Blockade of the TIGIT and PD-1/PD-L1 Pathway as a New Hope for Ovarian Cancer Patients

The prognosis for ovarian cancer (OC) patients is poor and the five-year survival rate is only 47%. Immune checkpoints (ICPs) appear to be the potential targets in up-and-coming OC treatment. However, the response of OC patients to immunotherapy based on programmed cell death pathway (PD-1/PD-L1) inhibitors totals only 6-15%. The promising approach is a combined therapy, including other ICPs such as the T-cell immunoglobulin and ITIM domain/CD155/DNAX accessory molecule-1 (TIGIT/CD155/DNAM-1) axis. Preclinical studies in a murine model of colorectal cancer showed that the dual blockade of PD-1/PD-L1 and TIGIT led to remission in the whole studied group vs. the regression of the tumors with the blockade of a single pathway. The approach stimulates the effector activity of T cells and NK cells, and redirects the immune system activity against the tumor. The understanding of the synergistic action of the TIGIT and PD-1/PD-L1 blockade is, however, poor. Thus, the aim of this review is to summarize the current knowledge about the mode of action of the dual TIGIT and PD-1/PD-L1 blockade and its potential benefits for OC patients. Considering the positive impact of this combined therapy in malignancies, including lung and colorectal cancer, it appears to be a promising approach in OC treatment.

Suppressive mechanisms of regulatory B cells in mice and humans

B cells include immune-suppressive fractions, called regulatory B cells (Bregs), which regulate inflammation primarily through an interleukin 10 (IL-10)-mediated inhibitory mechanism. Several B-cell fractions have been reported as IL-10-producing Bregs in murine disease models and human inflammatory responses including autoimmune diseases, infectious diseases, cancer and organ-transplant rejection. Although the suppressive functions of Bregs have been explored through the hallmark molecule IL-10, inhibitory cytokines and membrane-binding molecules other than IL-10 have also been demonstrated to contribute to Breg activities. Transcription factors and surface antigens that are characteristically expressed in Bregs are also being elucidated. Nevertheless, defining Bregs is still challenging because their active periods and differentiation stages vary among disease models. The identity of the diverse Breg fractions is also under debate. In the first place, since regulatory functions of Bregs are mostly evaluated by ex vivo stimulation, the actual in vivo phenotypes and functions may not be reflected by the ex vivo observations. In this article, we provide a historical overview of studies that established the characteristics of Bregs and review the various suppressive mechanisms that have been reported to be used by Bregs in murine and human disease conditions. We are only part-way through but the common phenotypes and functions of Bregs are still emerging.

Underlying mechanisms of evasion from NK cells as rational for improvement of NK cell-based immunotherapies

Natural killer (NK) cells belong to the family of innate immune cells with the capacity to recognize and kill tumor cells. Different phenotypes and functional properties of NK cells have been described in tumor patients, which could be shaped by the tumor microenvironment. The discovery of HLA class I-specific inhibitory receptors controlling NK cell activity paved the way to the fundamental concept of modulating immune responses that are regulated by an array of inhibitory receptors, and emphasized the importance to explore the potential of NK cells in cancer therapy. Although a whole range of NK cell-based approaches are currently being developed, there are still major challenges that need to be overcome for improved efficacy of these therapies. These include escape of tumor cells from NK cell recognition due to their expression of inhibitory molecules, immune suppressive signals of NK cells, reduced NK cell infiltration of tumors, an immune suppressive micromilieu and limited in vivo persistence of NK cells. Therefore, this review provides an overview about the NK cell biology, alterations of NK cell activities, changes in tumor cells and the tumor microenvironment contributing to immune escape or immune surveillance by NK cells and their underlying molecular mechanisms as well as the current status and novel aspects of NK cell-based therapeutic strategies including their genetic engineering and their combination with conventional treatment options to overcome tumor-mediated evasion strategies and improve therapy efficacy.

High Expression of the Costimulatory Checkpoint Factor DNAM-1 by CD4+ T-Cells from Multiple Myeloma Patients Refractory to Daratumumab-Containing Regimens

Multiple myeloma is an incurable disease characterized by unregulated growth of malignant plasma cells in the bone marrow (BM). Tumor-induced dysfunction of T-cells may be responsible for immune evasion and failure of immunotherapy. Therefore, a better understanding of the phenotype of T-cells at the tumor site is needed. We assessed the expression of immune regulatory receptors on T-cell subsets from peripheral blood (PB) and BM using multicolor flow cytometry. Paired PB and BM samples were collected from newly diagnosed, treatment-naïve myeloma patients (n = 19) and patients progressing during treatment with the CD38 monoclonal antibody daratumumab alone or in combination with other anti-myeloma drugs (n = 39). We observed that CD4+ T-cells from both PB and BM of patients relapsing on daratumumab have a higher expression of the costimulatory checkpoint receptor DNAM-1. The potential role of DNAM-1+CD4+ T-cells in the development of resistance to daratumumab needs further exploration. We also observed that the inhibitory checkpoint receptor TIGIT is more frequently expressed by BM CD8+ T-cells from myeloma patients than PD-1 and CTLA-4, which supports the hypothesis that TIGIT may play a central role in the immune escape of the malignant plasma cells.

CD155 in tumor progression and targeted therapy

CD155, also known as the poliovirus receptor (PVR), has received considerable attention in recent years because of its intrinsic and extrinsic roles in tumor progression. Although barely expressed in host cells, CD155 is upregulated in tumor-infiltrating myeloid cells. High expression of CD155 in tumor cells across multiple cancer types is common and associated with poor patient outcomes. The intrinsic functions of CD155 in tumor cells promote tumor progression and metastasis, whereas its extrinsic immunoregulatory functions in the tumor microenvironment (TME) involve interaction with the upregulated inhibitory immune cell receptor and checkpoint TIGIT, suggesting that CD155 and CD155 pathways are promising tumor immunotherapy targets. Preclinical studies demonstrate that targeting CD155 and its receptor (anti-TIGIT) using a single treatment or in combination with anti-PD-1 can improve immune-mediated tumor control. However, there is still a limited understanding of CD155 and its associated targeting strategies, especially antibody and immune cell editing-related strategies of CD155 in cancer. Here, we review the role of CD155 in host and tumor cells in controlling tumor progression and discuss the potential of targeting CD155 for tumor therapy.

Plasticity of natural killer cells in pregnant patients infected with SARS-CoV-2 and their neonates during childbirth

The COVID-19 pandemic has occurred due to infection caused by the SARS-CoV-2 coronavirus, which impacts gestation and pregnancy. In SARS-CoV-2 infection, only very rare cases of vertical transmission have been reported, suggesting that fetal immune imprinting due to a maternal infection is probably a result of changes in maternal immunity. Natural killer (NK) cells are the leading maternal immune cells that act as a natural defense system to fight infections. They also play a pivotal role in the establishment and maintenance of pregnancy. While peripheral NK cells display specific features in patients infected with SARS-CoV-2 in the general population, information remains elusive in pregnant mothers and neonates. In the present study, we analyzed the characteristics of NK cells isolated from both neonatal umbilical cord blood and maternal peripheral blood close to the time of delivery. Phenotype and functions were compared in 18 healthy pregnant women and 34 COVID-19 patients during pregnancy within an ongoing infection (PCR⁺; N = 15) or after recovery (IgG⁺PCR⁻; N = 19). The frequency of NK cells from infected women and their neonates was correlated with the production of inflammatory cytokines in the serum. The expression of NKG2A and NKp30, as well as degranulation of NK cells in pregnant women with ongoing infection, were both negatively correlated to estradiol level. Furthermore, NK cells from the neonates born to infected women were significantly decreased and also correlated to estradiol level. This study highlights the relationship between NK cells, inflammation, and estradiol in patients with ongoing infection, providing new insights into the impact of maternal SARS-CoV-2 infection on the neonate.