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The view of prostate cancer (PCa) progression as a result of the interaction of epithelial cancer cells with the host's immune system is supported by the presence of tumor infiltrating lymphocytes (TILs). TILs fate and interaction with the tumor microenvironment is mediated by accessory molecules such as CD5 and CD6, two signal-transducing coreceptors involved in fine-tuning of T cell responses. While the nature of the CD5 ligand is still controversial, CD6 binds CD166/ALCAM, a cell adhesion molecule involved in progression and dissemination of epithelial cancers, including PCa. The purpose of the present study was to determine the role of CD5, CD6, and CD166/ALCAM gene variants in PCa.Functionally relevant CD5 (rs2241002 and rs2229177), CD6 (rs17824933, rs11230563, and rs12360861) and CD166/ALCAM (rs6437585, rs579565, rs1044243, and rs35271455) single nucleotide polymorphisms (SNPs) were genotyped in germline DNA samples from 376 PCa patients. Their association with PCa prognostic factors, namely biochemical recurrence (BCR) and International Society of Urological Pathology (ISUP) grade was analyzed by generalized linear models and survival analyses.Proportional hazards regression showed that the minor CD6 rs12360861The results show the impact on PCa aggressiveness and recurrence brought about by gene variants involved in modulation of lymphocyte activation (CD5, CD6) and immune-epithelial cell adhesion (CD166/ALCAM) in PCa aggressiveness and recurrence, thus supporting a role for host immune response in PCa pathophysiology.

Atopic dermatitis (AD) and psoriasis represent two of the most common inflammatory skin diseases in developed countries. A hallmark of both diseases is T cell infiltration into the skin. However, it is still not clarified to what extent these infiltrating T cells are antigen-specific skin-homing T cells or unspecific heterogeneous bystander cells. To elucidate this, T cells from lesional skin and from blood of 10 AD and 11 psoriasis patients were compared by receptor (TCR) sequencing. Therefore, peripheral blood mononuclear cells (PBMC) were cell-sorted according to expression of the cutaneous leukocyte antigen (CLA) into skin-homing (CLA+) and non-skin-homing (CLA-) subfractions. Aeroallergen-specific T cell lines were grown from AD patients’ s PBMC in parallel. Intra-individual comparison of TCRB CDR3 regions revealed that clonally expanded T cells in skin lesions of both AD and psoriasis patients corresponded to skin-homing circulating T cells. However, in psoriasis patients, these T cell clones were also detectable to a larger extent among CLA- circulating T cells. Up to 28% of infiltrating cells were identified as allergen-specific by overlapping TCR sequences. Our data shows that in line with the systemic nature of psoriasis, T cells infiltrating psoriatic skin lesions do not exclusively home to the skin and are therefore not specific to antigens that are exclusively encountered at the skin. T cells driving AD skin inflammation appear to home nearly exclusively to the skin and are, to a certain extent, specific to aeroallergens. One Sentence Summary In contrast to psoriasis, T cells driving atopic dermatitis are predominantly skin-homing and are to a certain extent allergen-specific Key Message / Significance Statement T cells that encounter their cognate antigen proliferate clonally and share the same T cell receptor (TCR). Here we describe that clonally expanded T cells from lesional skin in patients with psoriasis and atopic dermatitis (AD) can also be detected within the circulation. While in AD these are mostly homing to the skin, psoriasis-driving T cells do not appear to be exclusively skin-directed. The fact that several co-morbidities are associated with psoriasis matches this observation. In contrast, AD is commonly accompanied by allergic sensitizations. Here we demonstrate that allergen-specific T cells do indeed infiltrate lesional skin and allow a concrete estimate of their frequency.

The interaction of inhibitory receptors with self–MHC class I (MHC-I) molecules is responsible for NK cell education. The intensity of DNAM-1 expression correlates with NK cell education. However, whether DNAM-1 expression directly influences the functional competence of NK cells via the KIR/MHC-I interaction remains unclear. Based on allogeneic haploidentical hematopoietic stem cell transplantation, we investigated the intensity of DNAM-1 expression on reconstituted NK cells via the interaction of KIR with both donor HLA and recipient HLA at days 30, 90, and 180 after hematopoietic stem cell transplantation. The reconstituted NK cells educated by donor and recipient HLA molecules showed the highest DNAM-1 expression, whereas DNAM-1 expression on educated NK cells with only recipient HLA molecules was higher than that on educated NK cells with only donor HLA molecules, indicating that NK cells with donor or recipient HLA molecules regulate DNAM-1 expression and thereby affect NK cell education. Additionally, the effects of recipient cells on NK cell education were greater than those of donor cells. However, only when the DNAM-1, NKP30, and NKG2D receptors were blocked simultaneously was the function of educated and uneducated NK cells similar. Therefore, activating receptors may collaborate with DNAM-1 to induce educated NK cell hyperresponsiveness. Our data, based on in vitro and in vivo studies, demonstrate that the functional competence of NK cells via the KIR/MHC-I interaction correlates with DNAM-1 expression in human NK cells.

B cell-activating factor (BAFF) binds the three receptors BAFF-R, BCMA, and TACI, predominantly expressed on mature B cells. Almost all B cell cancers are reported to express at least one of these receptors. Here we develop a BAFF ligand-based chimeric antigen receptor (CAR) and generate BAFF CAR-T cells using a non-viral gene delivery method. We show that BAFF CAR-T cells bind specifically to each of the three BAFF receptors and are effective at killing multiple B cell cancers, including mantle cell lymphoma (MCL), multiple myeloma (MM), and acute lymphoblastic leukemia (ALL), in vitro and in vivo using different xenograft models. Co-culture of BAFF CAR-T cells with these tumor cells results in induction of activation marker CD69, degranulation marker CD107a, and multiple proinflammatory cytokines. In summary, we report a ligand-based BAFF CAR-T capable of binding three different receptors, minimizing the potential for antigen escape in the treatment of B cell cancers., Antigen escape represents a potential drawback of chimeric antigen receptor T cell (CAR-T) therapy targeting a single tumor-associated antigen. To reduce the risk of antigen escape, here the authors report the design and characterization of a BAFF ligand CAR-T that can recognize three different receptors (BAFF-R, BCMA and TACI), demonstrating in vitro and in vivo cytotoxicity against multiple B cell cancer models.

The co-stimulatory and co-inhibitory immunoreceptors, DNAX accessory molecule-1 (DNAM-1) and T-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT), are paired activating and inhibitory receptors on T cells and natural killer (NK) cells. They share the ligands poliovirus receptor (PVR, CD155) and its family member nectin-2 (CD112), which are highly expressed on antigen-presenting cells (APCs), tumors and virus-infected cells. Upon ligation with the ligands, DNAM-1 and TIGIT show reciprocal functions; whereas DNAM-1 promotes activation, proliferation, cytokine production and cytotoxic activity in effector lymphocytes, including CD4+ T-helper cells, CD8+ cytotoxic T lymphocytes and NK cells, TIGIT inhibits these DNAM-1 functions. On the other hand, DNAM-1 competes with TIGIT on regulatory T (Treg) cells in binding to CD155 and therefore regulates TIGIT signaling to down-regulate Treg cell function. Thus, whereas DNAM-1 enhances anti-tumor immunity and inflammatory responses by augmenting effector lymphocyte function and suppressing Treg cell function, TIGIT reciprocally suppresses these immune responses by suppressing effector lymphocyte function and augmenting Treg cell function. Thus, blockade of DNAM-1 and TIGIT function would be potential therapeutic approaches for patients with inflammatory diseases and those with cancers and virus infection, respectively.

DNAM-1 is an activating immunoreceptor on T cells and natural killer (NK) cells. Expression levels of its ligands, CD155 and CD112, are up-regulated on tumor cells. The interaction of DNAM-1 on CD8+ T cells and NK cells with the ligands on tumor cells plays an important role in tumor immunity. We previously reported that mice deficient in DNAM-1 showed accelerated growth of tumors induced by the chemical carcinogen 7,12-dimethylbenz[a]anthracene (DMBA). Contrary to those results, we show here that tumor development induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) together with DMBA was suppressed in DNAM-1–deficient mice. In this model, DNAM-1 enhanced IFN-γ secretion from conventional CD4+ T cells to promote inflammation-related tumor development. These findings suggest that, under inflammatory conditions, DNAM-1 contributes to tumor development via conventional CD4+ T cells.

BackgroundCD6 is one of many cell surface receptors known to regulate signal transduction upon T cell activation. However, whether CD6 mediates costimulatory or inhibitory signals is controversial. When T cells engage with antigen presenting cells (APCs), CD6 interacts with its ligand CD166 at the cell–cell interface while the cytosolic tail assembles a complex signalosome composed of adaptors and effector enzymes, that may either trigger activating signaling cascades, or instead modulate the intensity of signaling. Except for a few cytosolic adaptors that connect different components of the CD6 signalosome, very little is known about the mechanistic effects of the cytosolic effectors that bind CD6.MethodsJurkat model T cells were transfected to express wild-type (WT) CD6, or a cytoplasmic truncation, signaling-disabled mutant, CD6Δcyt. The two resulting cell lines were directly activated by superantigen (sAg)-loaded Raji cells, used as APCs, to assess the net signaling function of CD6. The Jurkat cell lines were further adapted to express a FRET-based unimolecular HRas biosensor that reported the activity of this crucial GTPase at the immunological synapse.ResultsWe show that deletion of the cytosolic tail of CD6 enhances T-cell responses, indicating that CD6 restrains T-cell activation. One component of the CD6-associated inhibitory apparatus was found to be the GTPase activating protein of Ras (RasGAP), that we show to associate with CD6 in a phosphorylation-dependent manner. The FRET HRas biosensor that we developed was demonstrated to be functional and reporting the activation of the T cell lines. This allowed to determine that the presence of the cytosolic tail of CD6 results in the down-regulation of HRas activity at the immunological synapse, implicating this fundamental GTPase as one of the targets inhibited by CD6.ConclusionsThis study provides the first description of a mechanistic sequence of events underlying the CD6-mediated inhibition of T-cell activation, involving the modulation of the MAPK pathway at several steps, starting with the coupling of RasGAP to the CD6 signalosome, the repression of the activity of Ras, and culminating in the reduction of ERK1/2 phosphorylation and of the expression of the T-cell activation markers CD69 and IL-2R α chain.

CD226 interacts with its ligand Necl5 as a costimulatory signal. In this study, we cloned a CD226 from Nile tilapia (Oreochromis niloticus, named OnCD226) and a Necl5 (named OnNecl5). The open reading frame of OnCD226 was 1071 bp, encoding a protein of 356 amino acids. Sequence alignment analysis indicated that OnCD226 contained two Ig-like domains in ectodomain. The open reading frame of OnNecl5 was 1155 bp, encoding a protein of 384 amino acids, and there are three lg-like domains in the extracellular domain. In healthy tilapia, OnCD226 was distributed in all tested tissues and relatively higher in the brain, while OnNecl5 was relatively higher in the skin. After Streptococcus agalactiae infection, OnCD226 has the same up-regulated expression pattern as OnNecl5 in different tissues. After HKLs stimulation with S. agalactiae and Poly I:C, respectively. OnCD226 was significantly up-regulated (0.01p 0.05) at 12 h and extremely significant up-regulation was observed (p 0.01) at 48 h and 96 h, the peak was observed at 96 h after stimulation by S. agalactiae. After stimulation by Poly I:C, OnCD226 expression was extremely significant (p 0.01) at 72 h and 96 h, the peak was observed at 96 h. After stimulation by Keyhole limpet hemocyanin (KLH), a classical T cell-dependent antigen, the expression of OnCD226 was significantly up-regulated in blood, head kidney, spleen, and thymus. Moreover, when compared with the first challenge, the gene expression of OnCD226 which response to the second challenge was up-regulated earlier. Subcellular co-localization studies showed that OnCD226 and OnNecl5 were distributed mainly in the cytomembrane. Yeast two-hybrid results, indicated a strong interaction between OnCD226 and OnNecl5. These results suggested that OnCD226 plays an important role during pathogens infection, and the interaction between CD226 and Necl5 is conserved in Nile tilapia.

DNAM-1 is reportedly expressed on cytotoxic T and NK cells and, upon interaction with its ligands CD112 and CD155, plays an important role in tumor immunosurveillance. It has also been reported to be functionally expressed by myeloid cells, but expression and function on malignant cells of the myeloid lineage have not been studied so far. Here we analyzed expression of DNAM-1 in leukemic cells of acute myeloid leukemia (AML) patients. We found substantial levels of DNAM-1 to be expressed on leukemic blasts in 48 of 62 (> 75%) patients. Interaction of DNAM-1 with its ligands CD112 and CD155 induced release of the immunomodulatory cytokines IL-6, IL-8 IL-10 and TNF-α by AML cells and DNAM-1 expression correlated with a more differentiated phenotype. Multivariate analysis did not show any association of DNAM-1 positivity with established risk factors, but expression was significantly associated with clinical disease course: patients with high DNAM-1 surface levels had significantly longer progression-free and overall survival compared to DNAM-1low patients, independently whether patients had undergone allogenic stem cell transplantation or not. Together, our findings unravel a functional role of DNAM-1 in AML pathophysiology and identify DNAM-1 as a potential novel prognostic maker in AML.

OBJECTIVE Multiple myeloma is an incurable hematological malignancy. Currently, the use of proteasome inhibitors could be superior to chemotherapy-based regimen in the treatment of this disease. However, resistance to bortezomib combination therapy still occurs in some patients. So, this research work aims to assess CD69 and CD56 expression in these cases and their relation to the response to therapy. MATERIALS AND METHODS Immunophenotyping by 4-color multi-parameter flow cytometry was carried out on 98 multiple myeloma cases. Clonal plasma cells were gated by co-expression of CD38 with CD138 with low SSC, negative or dim CD45. RESULTS Double negative CD69 and CD56 (47.9%) multiple myeloma cases were associated with high serum β2 microglobulin, creatinine, calcium and low serum albumin. There was also a significant correlation between the absence of these markers with osteolytic lesions and unfavorable cytogenetic t (4;14) (p

CD4+ T cells not only direct immune responses against infectious micro-organisms but are also involved in the pathogenesis of inflammatory diseases. In the last two to three decades, various researchers have identified and characterized several functional CD4+ T-cell subsets, including T-helper 1 (Th1), Th2, Th9 and Th17 cells and regulatory T (Treg) cells. In this mini-review, we introduce the concept of pathogenic Th cells that induce inflammatory diseases with a model of disease induction by a population of pathogenic Th cells: the ‘pathogenic Th population disease-induction model’. We will focus on Th2 cells that induce allergic airway inflammation—pathogenic Th2 cells (Tpath2 cells)—and discuss the nature of Tpath2 cells that shape the pathology of chronic inflammatory diseases. Various Tpath2-cell subsets have been identified and their unique features are summarized in mouse and human systems. Second, we will discuss how Th cells migrate and are maintained in chronic inflammatory lesions. We propose a model known as the ‘CD69–Myl9 system’. CD69 is a cell surface molecule expressed on activated T cells and interaction with its ligand myosin light chain 9 (Myl9) is required for the induction of inflammatory diseases. Myl9 molecules in the small vessels of inflamed lungs may play a crucial role in the migration of activated T cells into inflammatory lesions. Emerging evidence may provide new insight into the pathogenesis of chronic inflammatory diseases and contribute to the development of new therapeutic strategies for intractable inflammatory disorders.

Immune checkpoint molecules, also known as cosignaling molecules, are pivotal cell-surface molecules that control immune cell responses by either promoting (costimulatory molecules) or inhibiting (coinhibitory molecules) a signal. These molecules have been studied for many years. The application of immune checkpoint drugs in the clinic provides hope for cancer patients. Recently, the poliovirus receptor (PVR)-like protein cosignaling network, which involves several immune checkpoint receptors, i.e., DNAM-1 (DNAX accessory molecule-1, CD226), TIGIT (T-cell immunoglobulin (Ig) and immunoreceptor tyrosine-based inhibitory motif (ITIM)), CD96 (T cell activation, increased late expression (TACLILE)), and CD112R (PVRIG), which interact with their ligands CD155 (PVR/Necl-5), CD112 (PVRL2/nectin-2), CD111 (PVRL1/nectin-1), CD113 (PVRL3/nectin-3), and Nectin4, was discovered. As important components of the immune system, natural killer (NK) and T cells play a vital role in eliminating and killing foreign pathogens and abnormal cells in the body. Recently, increasing evidence has suggested that this novel cosignaling network axis costimulates and coinhibits NK and T cell activation to eliminate cancer cells after engaging with ligands, and this activity may be effectively targeted for cancer immunotherapy. In this article, we review recent advances in research on this novel cosignaling network. We also briefly outline the structure of this cosignaling network, the signaling cascades and mechanisms involved after receptors engage with ligands, and how this novel cosignaling network costimulates and coinhibits NK cell and T cell activation for cancer immunotherapy. Additionally, this review comprehensively summarizes the application of this new network in preclinical trials and clinical trials. This review provides a new immunotherapeutic strategy for cancer treatment.

Vγ9Vδ2 T cells are attractive effector cells for immunotherapy with potent cytotoxic activity against a variety of malignant cells. However, the effect of Vγ9Vδ2 T cells on chemotherapy‐resistant acute myeloid leukemia (AML) blasts, especially highly refractory leukemia stem cells (LSCs) is still unknown. In this study, we investigated the effect of cytotoxicity of allogeneic Vγ9Vδ2 T cells on chemotherapy‐resistant AML cell lines, as well as on primary AML blasts and LSCs obtained from refractory AML patients. The results indicated that Vγ9Vδ2 T cells can efficiently kill drug‐resistant AML cell lines in vitro and in vivo, and the sensitivity of AML cells to Vγ9Vδ2 T cell–mediated cytotoxicity is not influenced by the sensitivity of AML cells to chemotherapy. We further found that Vγ9Vδ2 T cells exhibited a comparable effect of cytotoxicity against LSCs to primary AML blasts. More importantly, we revealed that the CD226–extracellular signal–regulatory kinase1/2 (ERK1/2)–lysosome‐associated membrane protein 1 (LAMP1) pathway is an important mechanism for Vγ9Vδ2 T cell–induced cytotoxicity against AML cells. First, Vγ9Vδ2 T cells recognized AML cells by receptor‐ligand interaction of CD226–Nectin‐2, which then induced ERK1/2 phosphorylation in Vγ9Vδ2 T cells. Finally, triggering the movement of lytic granules toward AML cells induced cytolysis of AML cells. The expression level of Nectin‐2 may be used as a novel marker to predict the susceptibility/resistance of AML cells to Vγ9Vδ2 T cell treatment., In this study, we indicated that Vγ9Vδ2 T cells can efficiently kill drug‐resistant acute myeloid leukemia (AML) cell lines in vitro and in vivo. We further found that Vγ9Vδ2 T cells exhibited a comparable effect of cytotoxicity against leukemia stem cells (LSCs) to primary AML blasts. More importantly, we revealed that Vγ9Vδ2 T cells induced cytotoxicity against AML cells via the CD226–extracellular signal–regulatory kinase1/2 (ERK1/2)–lysosome‐associated membrane protein 1 (LAMP1) pathway.

This article belongs to the Special Issue Lipids as Supporting Therapy in Cancer., Nine kDa granulysin (GRNLY) is a human cytolytic protein secreted by cytotoxic T lymphocytes (CTL) and NK cells of the immune system whose demonstrated physiological function is the elimination of bacteria and parasites. In previous studies by our group, the anti-tumor capacity of recombinant granulysin was demonstrated, both in vitro and in vivo. In the present work, we developed lipid nanoparticles whose surfaces can bind recombinant granulysin through the formation of a complex of coordination between the histidine tail of the protein and Ni2+ provided by a chelating lipid in the liposome composition and termed them LUV-GRNLY, for granulysin-bound large unilamellar vesicles. The objective of this formulation is to increase the granulysin concentration at the site of contact with the target cell and to increase the cytotoxicity of the administered dose. The results obtained in this work indicate that recombinant granulysin binds to the surface of the liposome with high efficiency and that its cytotoxicity is significantly increased when it is in association with liposomes. In addition, it has been demonstrated that the main mechanism of death induced by both granulysin and LUV-GRNLY is apoptosis. Jurkat-shBak cells are resistant to GRNLY and also to LUV-GRNLY, showing that LUV-GRNLY uses the mitochondrial apoptotic pathway to induce cell death. On the other hand, we show that LUV-GRNLY induces the expression of the pro-apoptotic members of the Bcl-2 family Bim and especially PUMA, although it also induced the expression of anti-apoptotic Bcl-xL. In conclusion, we demonstrate that binding of GRNLY to the surfaces of liposomes clearly augments its cytotoxic potential, with cell death executed mainly by the mitochondrial apoptotic pathway., This research was financed in part by the project PID2019-105128RB-I00 financed by MCIN/AEI/10.13039/501100011033/ and “FEDER Una manera de hacer Europa” to AA and IM and was also supported by Government of Aragon grant B31_20R to AA. PGO was supported by a Senescyt fellowship (Ecuador).

CD155 is a shared ligand for activating and inhibitory immunoreceptors DNAX accessory molecule 1 (DNAM-1), also called CD226, and T cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain (TIGIT), which are expressed on natural killer (NK) cells and T cells, and positively and negatively regulates tumor immune responses, respectively. A recent study showed that the single nucleotide polymorphism rs1058402GA causing a mutation to Thr from Ala at residue 67 of CD155 is associated with worse overall survival of patients with small cell lung cancer and suggested that this is caused by the decreased affinity of mutant CD155 for DNAM-1 as a result of the 3D structural analysis. Unexpectedly, however, we found that the mutation increased the binding affinity for TIGIT rather than decreased the binding affinity for DNAM-1 and induced a stronger signal than WT CD155. Our results suggest that the mutation suppresses tumor immune responses by generating a stronger inhibitory signal in immune cells in the tumor microenvironment.

T cell exhaustion refers to a dysfunctional state in which effector T cells present a decreased ability to proliferate and to produce cytokines, while the co-expression of inhibitory receptors increases. We investigated global and donor-specific T cell responses in a cohort of stable, living-donor kidney transplant patients that received similar immunosuppression. After transplantation, an increase in the ratio of TIGIT + /CD226 + in mCD4 + T cells (r = 0.47, p = 0.01), and a decrease of CD226 + TIGIT-mCD4 + T cells was observed (r = − 0.55, p = 0.001). This leads to an increase of dysfunctional T cells in patients far from transplantation. In mCD8 + T cells, a decrease of IL-2 production after mitogenic stimulation was observed far from transplantation. Phenotypic analyses revealed an increase of mCD8 + T cells co-expressing PD-1 and TIGIT over time (r = 0.51, p = 0.02). After donor-specific stimulation, the ability of CD4 + T cells to proliferate was decreased compared with third parties. CD4 + T cells expressing CD226 and TIGIT were correlated with allospecific CD4 + proliferation (r = 0.68, p = 0.04). Our study suggests that after kidney transplantation a T cell hyporesponsiveness appears over time, driven by a dysregulation of CD226/TIGIT axis in mCD4 + T cells, associated with an increase of PD1 + TIGIT + in mCD8 + T cells.

Alternative pre-mRNA splicing is a critical step to generate multiple transcripts, thereby dramatically enlarging the proteomic diversity. Thus, a common feature of most alternative splicing factor knockout models is lethality. However, little is known about lineage-specific alternative splicing regulators in a physiological setting. Here, we report that NSrp70 is selectively expressed in developing thymocytes, highest at the double-positive (DP) stage. Global splicing and transcriptional profiling revealed that NSrp70 regulates the cell cycle and survival of thymocytes by controlling the alternative processing of various RNA splicing factors, including the oncogenic splicing factor SRSF1. A conditional-knockout of Nsrp1 (NSrp70-cKO) using CD4Cre developed severe defects in T cell maturation to single-positive thymocytes, due to insufficient T cell receptor (TCR) signaling and uncontrolled cell growth and death. Mice displayed severe peripheral lymphopenia and could not optimally control tumor growth. This study establishes a model to address the function of lymphoid-lineage-specific alternative splicing factor NSrp70 in a thymic T cell developmental pathway.

The CD6 molecule, a cell surface marker, is involved in immunological synapse formation between T cell and antigen-presenting cell and T lymphocyte activation for adequate immune response. Geriatric individuals fail to mount a satisfactory immunological response against pathogens thus, insights into the functionality of CD6 may provide information for competence building in elderly immune cells. However, limited information is available regarding the status of CD6 in geriatric individuals. In this study, various isoforms of CD6 were analysed in aged mononuclear cells (MNCs) and compared with young individuals. In geriatric individuals, protein and mRNA expressions of CD6 molecule/isoforms were found to be decreased compared to their young counterparts. Furthermore, geriatric MNCs failed to show any change in CD6 levels and its isoforms upon polyclonal activation compared to young MNCs, marked by reduced Ca++ release and IL-2 expression. We suggest an overall decrease in CD6 levels in geriatric MNCs and T cells with suboptimal T cell activation in aged individuals.

Background Chronic alcohol consumption is associated with a compromised innate and adaptive immune response to infectious disease. Mucosa-associated invariant T (MAIT) cells play a critical role in antibacterial host defense. However, whether alcohol-associated deficits in innate and adaptive immune responses are mediated by alterations in MAIT cells remains unclear. Methods To investigate the impact of alcohol on MAIT cells, mice were treated with binge-on-chronic alcohol for 10 days and sacrificed at day 11. MAIT cells in the barrier organs (lung, liver and intestine) were characterized by flow cytometry. Two additional sets of animals were used to examine the involvement of gut microbiota on alcohol-induced MAIT cell changes. 1) Cecal microbiota from alcohol-fed (AF) mice were adoptive transferred into antibiotics-pretreated mice; 2) AF mice were treated with antibiotics during the experiment. MAIT cells in the barrier organs were measured via flow cytometry. Results Binge-on-chronic alcohol feeding led to a significant reduction in the abundance of MAIT cells in the barrier tissues. However, CD69 expression on tissue-associated MAIT cells was increased in AF mice compared to pair-fed (PF) mice. The expression of Th1 cytokines and the corresponding transcriptional factor was tissue specific with downregulation in the intestine, but increased in the lung and liver in alcohol-fed animals. Transplantation of fecal microbiota from AF mice resulted in a MAIT cell profile aligned to that of AF mice donor. Antibiotic treatment abolished the MAIT cell differences between AF and PF animals. Conclusion MAIT cells in the intestine, liver, and lung are perturbed by alcohol use, and these changes are, partially attributable to alcohol-associated dysbiosis. MAIT cell dysfunction may contribute to alcohol-induced, innate and adaptive immunity and consequently end-organ pathophysiology.

DNAM-1 is an activating immunoreceptor expressed on hematopoietic cells, including both CD4+ and CD8+ T cells, natural killer cells, and platelets. Since DNAM-1 is involved in the pathogenesis of various inflammatory diseases and cancers in humans as well as mouse models, it is a potential target for immunotherapy for these diseases. In this study, we generated a humanized neutralizing antihuman DNAM-1 monoclonal antibody (mAb), named TNAX101A, which contains an engineered Fc portion of human IgG1 to reduce Fc-mediated effector functions. We show that TNAX101A efficiently interfered the binding of DNAM-1 to its ligand CD155 and showed unique functions; it decreased production of the inflammatory cytokines such as interferon-gamma, tumor necrosis factor alpha, interleukin (IL)-6, IL-17A, and IL-17F by anti-CD3 antibody-stimulated or alloantigen-stimulated T cells and increased FOXP3 expression in anti-CD3-stimulated regulatory T (Treg) cells. These dual functions of TNAX101A may be advantageous for the treatment of T cell-mediated inflammatory diseases through both downregulation of effector T cell function and upregulation of Treg cell function.

T regulatory type 1 (Tr1) cells act as a key regulator in maintaining peripheral immune tolerance. Several costimulatory molecules for T cells have been identified in Tr1 cells, but their intrinsic functions are still unclear. Here we showed CD226 was highly expressed in Tr1 cells. CD226-deficient Tr1 cells were defective in proliferation and sensitive to apoptosis. In addition, CD226-deficient Tr1 cells showed lower inhibitory capacity of T cell proliferation and reduced IL-10 production. CD226 deficiency also inhibited Tr1 cell differentiation in vitro. When stimulated with IL-2, CD226-deficient Tr1 cells showed impaired STAT5 signaling. Therefore, our data suggest CD226 might play an important role in Tr1 cell homeostasis, function and differentiation. This study facilitates further biological characterization of this regulatory T cell subset.

In recent years, a set of immune receptors that interact with members of the nectin/nectin-like (necl) family has garnered significant attention as possible points of manipulation in cancer. Central to this axis, CD226, TIGIT, and CD96 represent ligand (CD155)-competitive co-stimulatory/inhibitory receptors, analogous to the CTLA-4/B7/CD28 tripartite. The identification of PVRIG (CD112R) and CD112 has introduced complexity and enabled additional nodes of therapeutic intervention. By virtue of the clinical progression of TIGIT antagonists and emergence of novel CD96- and PVRIG-based approaches, our overall understanding of the ‘CD226 axis’ in cancer immunotherapy is starting to take shape. However, several questions remain regarding the unique characteristics of, and mechanistic interplay between, each receptor-ligand pair. This review provides an overview of the CD226 axis in the context of cancer, with a focus on the status of immunotherapeutic strategies (TIGIT, CD96, and PVRIG) and their underlying biology (i.e.,cis/transinteractions). We also integrate our emerging knowledge of the immune populations involved, key considerations for Fc gamma (γ) receptor biology in therapeutic activity, and a snapshot of the rapidly evolving clinical landscape.

Autoimmune hepatitis (AIH) is characterized by the expansion and accumulation of pathogenic T cells in liver. Although CD6 and its ligand activated leukocyte cell adhesion molecule (ALCAM) are involved in the evolution of multiple inflammatory diseases, their roles in the pathogenesis of AIH remain unknown. Herein, we aimed to investigate ALCAM-CD6 axis in AIH development.Immunohistochemistry was performed to examine hepatic expression of CD6 and ALCAM. The concentration of serum ALCAM was evaluated by ELISA. The phenotypes of liver infiltrating T cells were determined by flow cytometry. Primary human CD4Our data showed that patients with AIH exhibited significantly higher expression of CD6 in the liver as compared to primary biliary cholangitis (PBC), chronic hepatitis B (CHB), non-alcoholic liver disease (NAFLD), and healthy controls (HC). In addition, hepatic CD6 expression was strongly correlated with disease severity of AIH. CD6 was mainly expressed on CD4Our study found that ALCAM-CD6 axis was upregulated in the AIH liver, suggesting a potential target for alleviating AIH.

The lipid chemoattractant sphingosine 1-phosphate (S1P) guides cells out of tissues, where the concentration of S1P is relatively low, into circulatory fluids, where the concentration of S1P is high1. For example, S1P directs the exit of T cells from lymph nodes, where T cells are initially activated, into lymph, from which T cells reach the blood and ultimately inflamed tissues1. T cells follow S1P gradients primarily using S1P receptor 1 (ref. 1). Recent studies have described how S1P gradients are established at steady state, but little is known about the distribution of S1P in disease or about how changing levels of S1P may affect immune responses. Here we show that the concentration of S1P increases in lymph nodes during an immune response. We found that haematopoietic cells, including inflammatory monocytes, were an important source of this S1P, which was an unexpected finding as endothelial cells provide S1P to lymph1. Inflammatory monocytes required the early activation marker CD69 to supply this S1P, in part because the expression of CD69 was associated with reduced levels of S1pr5 (which encodes S1P receptor 5). CD69 acted as a ‘stand-your-ground’ signal, keeping immune cells at a site of inflammation by regulating both the receptors and the gradients of S1P. Finally, increased levels of S1P prolonged the residence time of T cells in the lymph nodes and exacerbated the severity of experimental autoimmune encephalomyelitis in mice. This finding suggests that residence time in the lymph nodes might regulate the differentiation of T cells, and points to new uses of drugs that target S1P signalling. Monocyte-derived sphingosine 1-phosphate gradients in the lymph nodes regulate the response of T cells under inflammatory conditions.

T-Cell development is a major branch of lymphoid development and a key output of hematopoiesis, especially in early life, but the molecular requirements for T-cell potential have remained obscure. Considerable advances have now been made toward solving this problem through single-cell transcriptome studies, interfaced with in vitro differentiation assays that monitor potential efficiently at the single-cell level. This review focuses on a series of recent reports studying mouse and human early T-cell precursors, both in the developing fetus and in stringently purified postnatal samples of intrathymic and prethymic T-lineage precursors. Cross-comparison of results reveals a robustly conserved core program in mouse and human, but with some informative and provocative variations between species and between ontogenic states. Repeated findings are the multipotent progenitor regulatory signature of thymus-seeding cells and the proximity of the T-cell program to dendritic cell programs, especially to plasmacytoid dendritic cells in humans.

In COVID-19, the inflammatory cytokine-release syndrome is associated with the progression of the disease. Itolizumab is a monoclonal antibody that recognizes human CD6 expressed in activated T cells. The antibody has shown to be safe and efficacious in the treatment of moderate to severe psoriasis. Its effect is associated with the reduction of pro-inflammatory cytokines release, including IFN-γ, IL-6 and TNF-α. Here, we report the outcome of three severe and critically ill COVID-19 patients treated with itolizumab as part of an expanded access protocol. Itolizumab was able to reduce IL-6 concentrations in all the patients. Two of the three patients showed respiratory and radiological improvement and were fully recovered. We hypothesize this anti-inflammatory therapy in addition to antiviral and anticoagulant therapy could reduce COVID-19 associated morbidity and mortality., Lay abstract In COVID-19 patients, inflammation is associated with the progression of the disease. This inflammation comes from immune system activation in response to SARS-COV-2. Itolizumab is an antibody that recognizes a protein expressed in immune cells. The antibody has shown to be safe and efficacious in the treatment of moderate to severe psoriasis. Its effect is associated with the reduction of inflammation and immune system activation. Here, we report the outcome of three severe and critically ill COVID-19 patients treated with itolizumab as part of an expanded access clinical protocol. Itolizumab was able to reduce inflammation in all patients. Two of the three patients showed respiratory and radiological improvement and were fully recovered. We hypothesize this anti-inflammatory therapy in addition to antiviral and anticoagulant therapy could reduce COVID-19 associated morbidity and mortality.

Anticancer immunotherapies have revolutionized cancer management, yet the effect of systemic anti‐programmed cell death protein 1 (PD‐1) treatment is predominantly studied in tumor‐infiltrating lymphocytes (TILs). Its impact on PD‐1 expressing cells in tumor‐draining lymph nodes (TDLNs) is not well understood and yet to be explored. Thus, further research aiming for better understanding of the PD‐1 pathway not only in tumor tissue but also in TDLNs is warranted. In this study, we investigated the expression of PD‐1, CD69, and HLA‐DR on CD4+ and CD8+ T cells by flow cytometry analysis of peripheral blood mononuclear cells (PBMCs), TDLNs, and tumor samples from patients with oral squamous cell carcinoma (OSCC). Our data showed that both helper and cytotoxic T lymphocytes in OSCC tissue were highly activated and expressed high level of PD‐1 (over 70% positivity). Lymphocytes in TDLNs and peripheral blood expressed significantly lower levels of PD‐1 and other activation markers compared to TILs. Moreover, we demonstrated that a significant fraction of PD‐1 negative TILs expressed high levels of human leukocyte antigen – DR isotype and CD69. In contrast, PD‐1 negative cells in TDLNs and PBMCs scarcely expressed the aforementioned activation markers. Furthermore, we proved that patients with a high percentage of CD3+ PD‐1+ cells in tumor‐draining lymph nodes had significantly lower disease‐free and overall survival rates (log‐rank test P = .0272 and P = .0276, respectively). Taken together, we proved that flow cytometry of lymph nodes in OSCC is feasible and may be used to investigate whether PD‐1 levels in TDLNs correspond with survival and potentially with response to anti‐PD‐1 therapy. Such knowledge may ultimately help guide anti‐PD‐1 treatment., Flow cytometry is a powerful tool that can be used in head and neck cancers to investigate immunological milieu of tumor‐draining lymph nodes. In this project, we provide a characterization of T cells within head and neck cancer tumors, tumor‐draining lymph nodes, and blood.

In this study, we explored whether Nutlin-3a, a well-known, nontoxic small-molecule compound antagonizing the inhibitory interaction of MDM2 with the tumor suppressor p53, may restore ligands for natural killer (NK) cell–activating receptors (NK-AR) on neuroblastoma cells to enhance the NK cell–mediated killing. Neuroblastoma cell lines were treated with Nutlin-3a, and the expression of ligands for NKG2D and DNAM-1 NK-ARs and the neuroblastoma susceptibility to NK cells were evaluated. Adoptive transfer of human NK cells in a xenograft neuroblastoma-bearing NSG murine model was assessed. Two data sets of neuroblastoma patients were explored to correlate p53 expression with ligand expression. Luciferase assays and chromatin immunoprecipitation analysis of p53 functional binding on PVR promoter were performed. Primary neuroblastoma cells were also treated with Nutlin-3a, and neuroblastoma spheroids obtained from one high-risk patient were assayed for NK-cell cytotoxicity. We provide evidence showing that the Nutlin-3a–dependent rescue of p53 function in neuroblastoma cells resulted in (i) increased surface expression of ligands for NK-ARs, thus rendering neuroblastoma cell lines significantly more susceptible to NK cell–mediated killing; (ii) shrinkage of human neuroblastoma tumor masses that correlated with overall survival upon adoptive transfer of NK cells in neuroblastoma-bearing mice; (iii) and increased expression of ligands in primary neuroblastoma cells and boosting of NK cell–mediated disaggregation of neuroblastoma spheroids. We also found that p53 was a direct transcription factor regulating the expression of PVR ligand recognized by DNAM-1. Our findings demonstrated an immunomodulatory role of Nutlin-3a, which might be prospectively used for a novel NK cell–based immunotherapy for neuroblastoma.

Antibody-based therapeutics targeting the inhibitory receptors PD-1, PD-L1, or CTLA-4 have shown remarkable clinical progress on several cancers. However, most patients do not benefit from these therapies. Thus, many efforts are being made to identify new immune checkpoint receptor-ligand pathways that are alternative targets for cancer immunotherapies. Nectin and nectin-like molecules are widely expressed on several types of tumor cells and play regulatory roles in T- and NK-cell functions. TIGIT, CD226, CD96 and CD112R on lymphoid cells are a group of immunoglobulin superfamily receptors that interact with Nectin and nectin-like molecules with different affinities. These receptors transmit activating or inhibitory signals upon binding their cognate ligands to the immune cells. The integrated signals formed by their complex interactions contribute to regulating immune-cell functions. Several clinical trials are currently evaluating the efficacy of anti-TIGIT and anti-CD112R blockades for treating patients with solid tumors. However, many questions still need to be answered in order to fully understand the dynamics and functions of these receptor networks. This review addresses the rationale behind targeting TIGIT, CD226, CD96, and CD112R to regulate T- and NK-cell functions and discusses their potential application in cancer immunotherapy. [BMB Reports 2021; 54(1): 2-11].

Summary Immune checkpoint therapy to reverse natural killer (NK) and T cell exhaustion has emerged as a promising treatment in various cancers. While anti-programmed cell death 1 (PD-1) pembrolizumab has recently gained Food and Drug Administration (FDA) approval for use in recurrent or metastatic cervical cancer, other checkpoint molecules, such as T cell immunoreceptor with immunoglobulin (Ig) and immunoreceptor tyrosine-based inhibition motif (ITIM) domains (TIGIT) and T cell immunoglobulin and mucin-domain containing-3 (Tim-3), have yet to be fully explored in this disease. We report expression of TIGIT, Tim-3 and PD-1 on subsets of peripheral blood NK (CD56dim/negCD16bright/dim/neg and CD56brightCD16dim/neg) and T cells. The percentages of these cells were increased in women with cervical cancer and pre-malignant lesions. PD-1+ NK and T cells were likely to co-express TIGIT and/or Tim-3. These cells, with an apparently ‘exhausted’ phenotype, were augmented in patients. A subset of cells were also natural killer group 2 member D (NKG2D)- and DNAX accessory molecule 1 (DNAM-1)-positive. PD-1int and PD-1high T cells were notably increased in cervical cancer. Soluble programmed cell death ligand 1 (PD-L1) was higher in cancer patient blood versus healthy donors and we observed a positive correlation between sPD-L1 and PD-1+ T cells in women with low-grade lesions. Within the cancer group, there were no significant correlations between sPD-L1 levels and cervical cancer stage. However, when comparing cancer versus healthy donors, we observed an inverse association between sPD-L1 and total T cells and a correlation between sPD-L1 and CD56dim NK cells. Our results may show an overview of the immune response towards pre-cancerous lesions and cervical cancer, perhaps giving an early clue as to whom to administer blocking therapies. The increase of multiple checkpoint markers may aid in identifying patients uniquely responsive to combined antibody therapies.

Background T cell Ig and ITIM domain (TIGIT)/CD226 pathway has a critical role in regulating T cell responses and has come to the forefront in cancer as a promising immunotherapeutic target. However, its role in autoimmune diseases is just beginning to be elucidated. Dermatomyositis (DM) is an autoimmune disease, in which T cell dysregulation plays a pivotal role, and importantly, it is a common immune-related adverse event in response to treatment of cancers with immune checkpoint inhibitors, but no studies have implicated the TIGIT/CD226 axis in DM. Methods We recruited 30 treatment-naïve DM patients and 26 healthy controls. Flow cytometry analysis was used to investigate the co-expression of TIGIT and CD226 on T cells in blood samples. Magnetic bead or FACS-based cell isolation, T cell proliferation assay, and intracellular cytokine staining were performed to analyze the functions of different TIGIT/CD226 phenotypes. Recombinant proteins CD155, CD112, and anti-CD226 antibodies were used to suppress the function of TIGIT/CD226-expressing CD4 T cells. Results Four distinct subsets of T cells based on TIGIT/CD226 co-expression, TIGIT+CD226−, TIGIT+CD226+, TIGIT−CD226+, and TIGIT−CD226−, were identified and characterized in DM patients. Our data showed that the function of CD4 T cell subset varied by the TIGIT/CD226 phenotype. An elevated TIGIT+CD226+ CD4 subset with enhanced effector function was observed in patients with DM, especially the patients complicated with interstitial lung disease. This subpopulation was closely related to DM activity and decreased significantly in DM remission after treatment. Furthermore, the effector function of TIGIT+CD226+ CD4 subset could be suppressed by blocking CD226. Conclusion Our data revealed that the TIGIT and CD226 expression profiles could be used to identify functionally distinct subsets of CD4 T cells and TIGIT+CD226+ CD4 T cells is a significant subset in DM with enhanced frequency and effector function. This abnormal subset could be suppressed by blocking CD226, providing insight into the therapeutic target of the TIGIT/CD226 axis.

Activated Vγ9Vδ2 (γδ2) T lymphocytes that sense parasite-produced phosphoantigens are expanded in Plasmodium falciparum–infected patients. Although previous studies suggested that γδ2 T cells help control erythrocytic malaria, whether γδ2 T cells recognize infected red blood cells (iRBCs) was uncertain. Here we show that iRBCs stained for the phosphoantigen sensor butyrophilin 3A1 (BTN3A1). γδ2 T cells formed immune synapses and lysed iRBCs in a contact, phosphoantigen, BTN3A1 and degranulation-dependent manner, killing intracellular parasites. Granulysin released into the synapse lysed iRBCs and delivered death-inducing granzymes to the parasite. All intra-erythrocytic parasites were susceptible, but schizonts were most sensitive. A second protective γδ2 T cell mechanism was identified. In the presence of patient serum, γδ2 T cells phagocytosed and degraded opsonized iRBCs in a CD16-dependent manner, decreasing parasite multiplication. Thus, γδ2 T cells have two ways to control blood-stage malaria–γδ T cell antigen receptor (TCR)-mediated degranulation and phagocytosis of antibody-coated iRBCs. Junqueira et al. show that human γδ T cells control erythrocytic Plasmodium falciparum infection by multiple mechanisms: antibody-dependent phagocytosis, cytotoxic-granule-mediated erythrocyte lysis and direct parasite killing.

Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN) is a rare, immunologically mediated cutaneous adverse reaction characterized by mucous membrane and epidermal detachment, with a mortality ranging from 15% to 25%. Risk factors for the development of SJS/TEN include immune dysregulation, active malignancy, and genetic predisposition. Medications are the most common cause, particularly antimicrobials, antiepileptics, allopurinol, and nonsteroidal anti-inflammatory medications. Drug-specific CD8 T-cells and natural killer cells are thought to be the major inducers of keratinocyte apoptosis via release of soluble cytotoxic mediators, including Fas ligand, perforin/granzyme, tumor necrosis factor, and granulysin. When SJS/TEN is suspected clinically, appropriate therapy should be instituted without delay. All patients should be managed initially in an intensive care unit or burn unit under a multidisciplinary team of physicians experienced in the care of patients with SJS/TEN. Available data support the use of various pharmacologic agents to halt disease progression and improve outcomes, but no single drug has been found to be superior or beneficial for all patients. Future research should focus on developing a better understanding of the genetic susceptibility and immunopathophysiology of the disease, as well as novel diagnostic and therapeutic targets to improve patient outcomes.

Epigenetic gene silencing by aberrant DNA methylation is one of the important mechanisms leading to loss of key cellular pathways in tumorigenesis. Methyl‐CpG‐targeted transcriptional activation (MeTA) reactivates hypermethylation‐mediated silenced genes in a different way from DNA‐demethylating agents. Microarray coupled with MeTA (MeTA‐array) identified seven commonly hypermethylation‐mediated silenced genes in 12 pancreatic ductal adenocarcinoma (PDAC) cell lines. Among these, we focused on IRX4 (Iroquois homeobox 4) because IRX4 is located at chromosome 5p15.33 where PDAC susceptibility loci have been identified through genome‐wide association study. IRX4 was greatly downregulated in all of the analyzed 12 PDAC cell lines by promoter hypermethylation. In addition, the IRX4 promoter region was found to be frequently and specifically hypermethylated in primary resected PDACs (18/28: 64%). Reexpression of IRX4 inhibited colony formation and proliferation in two PDAC cell lines, PK‐1 and PK‐9. In contrast, knockdown of IRX4 accelerated cell proliferation in an IRX4‐expressing normal pancreatic ductal epithelial cell line, HPDE‐1. Because IRX4 is a sequence‐specific transcription factor, downstream molecules of IRX4 were pursued by microarray analyses utilizing tetracycline‐mediated IRX4 inducible PK‐1 and PK‐9 cells; CRYAB, CD69, and IL32 were identified as IRX4 downstream candidate genes. Forced expression of these genes suppressed colony formation abilities for both PK‐1 and PK‐9. These results suggest that DNA methylation‐mediated silencing of IRX4 contributes to pancreatic tumorigenesis through aberrant transcriptional regulation of several cancer‐related genes., IRX4 was found as a commonly hypermethylation‐mediated silenced gene in pancreatic ductal adenocarcinoma (PDAC) using the methyl‐CpG targeted transcriptional activation (MeTA) method. Promoter hypermethylation of IRX4 was seen in PDAC, reexpression of IRX4 inhibited proliferation in PDAC cell lines, and forced expression of IRX4 downstream genes suppressed colony formation abilities. These results suggest that DNA methylation‐mediated silencing of IRX4 contributes to pancreatic tumorigenesis through aberrant transcriptional regulation of several cancer‐related genes.

Duault and colleagues investigated samples from 20 patients with B- or T-cell acute lymphoblastic leukemia (ALL) and identified defective maturation of natural killer (NK) effector cells and accumulation of less cytotoxic hyperactivated cytokine-producing NK cells. Increased frequency of activated cytokine-producing NK cells is an independent predictor of poor clinical outcome in ALL. These findings suggest that NK cell profiling may have prognostic potential in this setting., Key Points Defective maturation of NK effector cells leads to accumulation of less cytotoxic hyperactivated cytokine-producing NK cells in patients with B/T-ALL.Increased frequency of activated cytokine-producing NK cells independently predicts poor clinical outcome in patients with ALL., B- and T-cell acute lymphoblastic leukemia (B/T-ALL) may be refractory or recur after therapy by suppressing host anticancer immune surveillance mediated specifically by natural killer (NK) cells. We delineated the phenotypic and functional defects in NK cells from high-risk patients with B/T-ALL using mass cytometry, flow cytometry, and in silico cytometry, with the goal of further elucidating the role of NK cells in sustaining acute lymphoblastic leukemia (ALL) regression. We found that, compared with their normal counterparts, NK cells from patients with B/T-ALL are less cytotoxic but exhibit an activated signature that is characterized by high CD56, high CD69, production of activated NK cell–origin cytokines, and calcium (Ca2+) signaling. We demonstrated that defective maturation of NK cells into cytotoxic effectors prevents NK cells from ALL from lysing NK cell–sensitive targets as efficiently as do normal NK cells. Additionally, we showed that NK cells in ALL are exhausted, which is likely caused by their chronic activation. We found that increased frequencies of activated cytokine-producing NK cells are associated with increased disease severity and independently predict poor clinical outcome in patients with ALL. Our studies highlight the benefits of developing NK cell profiling as a diagnostic tool to predict clinical outcome in patients with ALL and underscore the clinical potential of allogeneic NK cell infusions to prevent ALL recurrence.

Kidney transplantation is the ideal treatment for end-stage renal disease (ESRD). Chronic antibody-mediated rejection (CAMR) is the main cause of graft failure. Tfh and B cells are key immune cells that play important roles in CAMR. In this study, the populations of different Tfh cell phenotypes and B cell subsets in CAMR were investigated in a total of 36 patients. Based on Banff-2019, 15 patients were diagnosed with CAMR (CAMR group), 11 recipients were diagnosed with recurrent or de novo IgA nephropathy (IgAN group), and 10 patients displayed stable renal function (stable group). The Tfh and B cell subsets were analyzed by flow cytometry. The percentage and absolute number of PD-1

Recent advances in understanding the roles of immune checkpoints in allowing tumors to circumvent the immune system have led to successful therapeutic strategies that have fundamentally changed oncology practice. Thus far, immunotherapies against only two checkpoint targets have been approved, CTLA-4 and PD-L1/PD-1. Antibody blockade of these targets enhances the function of antitumor T cells at least in part by relieving inhibition of the T cell costimulatory receptor CD28. These successes have stimulated considerable interest in identifying other pathways that may bte targeted alone or together with existing immunotherapies. One such immune checkpoint axis is comprised of members of the PVR/nectin family that includes the inhibitory receptor T cell immunoreceptor with Ig and immunoreceptor tyrosine-based inhibitory domains (TIGIT). Interestingly, TIGIT acts to regulate the activity of a second costimulatory receptor CD226 that works in parallel to CD28. There are currently over two dozen TIGIT-directed blocking antibodies in various phases of clinical development, testament to the promise of modulating this pathway to enhance antitumor immune responses. In this review, we discuss the role of TIGIT as a checkpoint inhibitor, its interplay with the activating counter-receptor CD226, and its status as the next advance in cancer immunotherapy.

Costimulation pathways play an essential role in T cell activation, differentiation, and regulation. CD155 expressed on antigen-presenting cells (APCs) interacts with TIGIT, an inhibitory costimulatory molecule, and CD226, an activating costimulatory molecule, on T cells. TIGIT and CD226 are expressed at varying levels depending on the T cell subset and activation state. T follicular helper cells in germinal centers (GC-Tfh) in human tonsils express high TIGIT and low CD226. However, the biological role of the CD155/TIGIT/CD226 axis in human Tfh cell biology has not been elucidated. To address this, we analyzed tonsillar CD4+T cell subsets cultured with artificial APCs constitutively expressing CD155. Here we show that CD226 signals promote the early phase of Tfh cell differentiation in humans. CD155 signals promoted the proliferation of naïve CD4+T cells and Tfh precursors (pre-Tfh) isolated from human tonsils and upregulated multiple Tfh molecules and decreased IL-2, a cytokine detrimental for Tfh cell differentiation. Blocking CD226 potently inhibited their proliferation and expression of Tfh markers. By contrast, while CD155 signals promoted the proliferation of tonsillar GC-Tfh cells, their proliferation required only weak CD226 signals. Furthermore, attenuating CD226 signals rather increased the expression of CXCR5, ICOS, and IL-21 by CD155-stimulated GC-Tfh cells. Thus, the importance of CD226 signals changes according to the differentiation stage of human Tfh cells and wanes in mature GC-Tfh cells. High TIGIT expression on GC-Tfh may play a role in attenuating the detrimental CD226 signals post GC-Tfh cell maturation.