Inducible T-cell Costimulator Research Articles

TMIC-62. COMPLEMENT FACTOR H IS A NOVEL LIGAND FOR THE INDUCIBLE T CELL CO-STIMULATOR AND PROMOTES SURVIVAL OF REGULATORY T CELLS IN THE GLIOMA MICROENVIRONMENT

Abstract The survival rates of glioma patients have not shown significant improvement in recent years despite aggressive treatment and advancements in immunotherapy. This lack of response to treatment can be attributed in part to the immunosuppressive microenvironment commonly found in gliomas, where regulatory T cells (Tregs) play a critical role in immunologic tolerance. In this study, we aimed to investigate the influence of complement factor H (FH) on Tregs within the glioma microenvironment. Our findings revealed that FH acts as a novel ligand for the inducible T cell costimulator (ICOS). This interaction between FH and ICOS promotes the survival of Tregs. Furthermore, FH enhances the functional capabilities of Tregs that are crucial for modulating the tumor microenvironment. These include the secretion of transforming growth factor beta and interleukin 10, as well as the suppression of effector T cell proliferation. Immunostaining of human and mouse gliomas demonstrated that cancer cells directly produce FH. Additionally, database analysis revealed an association between upregulated FH expression, the presence of Tregs, and poor prognosis in glioma patients. We validated these findings in a glioma mouse model, where knockdown of FH expression showed a clear tendency to prolong survival. Given that the accumulation of Tregs is indicative of a poor prognosis and represents a promising target for therapy, it is crucial to consider FH expression when evaluating the effectiveness of immunotherapies against glioma.

Assessment of T-Cell Receptor (TCR) Mediated T-Cell Activation in Acute Myeloid Leukemia at Diagnosis Has Implications for Risk Stratification and Response to Immune Checkpoint Inhibitors

Background Relapse in patients with acute myeloid leukemia (AML) has been, in part, attributed to the ability of leukemic blasts to escape immune surveillance through mechanisms such as MHC class II antigen modulation, alteration of the cytokine milieu, and upregulation of inhibitory and immune checkpoint ligands that promote T-cell suppression. Yet, immune checkpoint inhibitors (ICI) used in AML have yielded variable and unpredictable results. Moreover, evaluation of T-cell function is not part of the diagnostic assessment of patients with AML. Methods To better characterize the T-cell dysfunction in AML, we conducted a prospective study on freshly harvested, bone marrow aspirates from patients with AML at presentation, collected under an Institutional IRB-approved banking protocol over the past two years. Using a multiparameter flow cytometry-based assay, we analyzed T-cell activation potential in response to CD3/CD28 (bead-based), T-cell receptor (TCR) stimulation, both alone (n= 40 AMLs and 10 healthy donors) or in combination with a library of ICI (n=15 AML and 5 healthy donors). We selected OX40 (CD134/TNFRSF4) and ICOS (Inducible T-cell costimulator) as surrogate markers for T-cell activation based on their expression pattern post bead-based stimulation in healthy donors' bone marrows. The ICI library comprised 31 therapeutic antibody inhibitors of known immune checkpoints, signaling pathways, and chemokines reported to be implicated in T-cell suppression in AML and other solid tumors. Results Healthy T-cells displayed the highest surface expression of OX40 and ICOS at 5 days post-bead-stimulation, which was selected as the endpoint for our in vitro analyses. We found that bone marrow-derived T-cells from healthy donors upregulated the expression of the markers ICOS and/or OX40 in at least 20% of T-cells post-stimulation (n= 10, ICOS: median 36.9%, range 20-72%; OX40: median 59.3%, range 21.4 -83%). Overall, AML samples displayed a lower degree of ICOS and OX40 T-cell expression in response to TCR stimulation (n=40, ICOS: median 20.5%, range 4-65%; OX-40: median 30.3%, range 0.3-80%). Based on this result, T-cell activation was defined as >20% CD3+ cells ICOS+/OX-40+ with stimulation, with greater than 2-fold changes from baseline ICOS and OX40 expression. Using this criterion, patients with AML were then classified as activators or non-activators. T-cell activation status correlated with ELN 2022 risk (1) (Figure 1A). For the intermediate risk group, we observed that the activators group had a significantly longer relapse-free survival when compared to the non-activators (Figure 1B, n=10, Mantel-Cox log-rank = 0.02, follow up 400 days at the time of writing). While a similar trend was observed in the favorable and the poor risk groups, it did not reach significance in these ELN categories. To assess if the T-cell activation could be rescued or augmented upon immune checkpoint inhibition, we tested the effect of each of the 31 compounds of the ICI library on the degree of T-cell activation in diagnosis bone marrow aspirates of 15 patients (7 activators and 8 non activators) and in 5 healthy donors. Matched peripheral blood (PB) samples were available for 5 of the 15 patients with AML. All tested normal donors reached the threshold for T-cell activation, which was not significantly affected by ICI treatment. The 7 AML activators behaved similarly to the healthy donors. In 2 of the 8 AML non-activators, selected ICI rescued T-cell activation in absence of TCR stimulation, while in the remaining 6 cases, T-cell activation was not achieved under any condition. Similar, but overall dampened activation trends, were observed in PB samples. Conclusions Consistent with the findings of our previous retrospective study (2), the ongoing prospective analysis of T-cell activation of diagnosis bone marrows of patients with AML suggests that testing TCR-mediated T-cell activation potential at diagnosis may help refine risk stratification of the heterogenous ELN intermediate risk group. AML immune suppression seems to be reversible in a minority of cases with the use of selected ICI inhibitors.

Tfh and Tfr Cells in Autoimmune Diseases

An immunological condition known as autoimmunity causes the excessive generation of autoantibodies against self-antigen and is characterized by enhanced T-cell activation and extra-stimulated B-cells. The development of lymphatic follicle germinal centers (GCs), the maturation of B cells, and differentiation into plasma cells are all significantly aided by follicular helper T cells (Tfh). Tfh cells express the transcriptional regulator B cell lymphoma 6 (BCL-6), C-X-C chemokine receptor 5 (CXCR5), inducible T cell co-stimulator (ICOS), and programmed cell death protein 1 (PD-1). The production of interleukin (IL)-21 and low expression of the chemokine (C-C motif) receptor 7 (CCR7) define Tfh cells. Additionally, Tfh cells are a diverse population of cells with the potential to co-express minute quantities of transcription factors, such as T-box expressed in T cells (T-bet), GATA-binding protein 3 (GATA-3), and retinoic acid receptor-related orphan receptor (ROR-t). Tfh cells that also produce IL-21, IL-4, IL-17, and IFN-γ are referred to as Tfh1, Tfh2, and Tfh17 cells, respectively. The control of humoral immunity is carried out by follicular regulatory (Tfr) cells that express Forkhead box protein 3 (Foxp3). Tfr cells can, however, decrease T-B cell interactions through the cytotoxic T lymphocyte-associated protein 4 (CTLA-4) while promoting B cell maturation through IL-10. In the context of autoimmunity, the role of Tfh and Tfr cells is still not fully understood. We intend to present the most recent data on the characteristics and function of Tfh and Tfr cells under conditions of autoimmunity in this review.

Expression and prognosis of inducible T-cell co-stimulator and its ligand in Chinese stage I-III lung adenocarcinoma patients.

Immunotherapy has become the fastest-adopting treatment paradigm for lung cancer with improved survival. By binding with its ligand (inducible T-cell co-stimulator and its ligand [ICOSL]), an inducible T-cell co-stimulator (ICOS) could contribute to reversing immunosuppression and improving immune response and thus be a potential target for cancer immunotherapy. We selected 54 formalin-fixed, paraffin-embedded tumor tissues from cases with stage I-III lung adenocarcinoma cancer. Immunohistochemical expression of ICOS and ICOSL was evaluated. The correlation with clinical parameters in Chinese patients was also compared with TCGA results. The positive rates of ICOS and ICOSL were 68% and 81.5%, respectively, in lung tumor tissues. Of these, 9 cases had a low expression of ICOS, and 22 cases had a high expression of ICOS; ICOSL expression was low in 20 cases and high in 24 cases. According to the International Association for the Study of Lung Cancer (8th edition), phase I lesions were detected in 21 cases, phase II lesions in 15 cases, and phase III lesions in 18 cases. The median survival time of all patients was 44.5 months, and the median disease-free survival was 32 months. Univariate analysis showed that the factors significantly associated with overall survival were tumor size, regional lymph node involvement, stage, and expression level of ICOS/ICOSL. Survival analysis using log-rank test indicated that the lower ICOS+ cell infiltration may predict poor prognosis, whereas lower ICOSL protein expression may be associated with better prognosis, but ICOSL data need further validation in larger samples due to inconsistency in TCGA mRNA prediction. ICOS/ICOSL might be associated with prognosis of lung cancer, and ICOS and its ligand may be potential therapeutic targets in non-small cell lung cancer.

T Follicular Helper Cells in Tertiary Lymphoid Structure Contribute to Renal Fibrosis by IL-21.

Tertiary lymphoid structure (TLS) represents lymphocyte clusters in non-lymphoid organs. The formation and maintenance of TLS are dependent on follicular helper T (TFH) cells. However, the role of TFH cells during renal TLS formation and the renal fibrotic process has not been comprehensively elucidated in chronic kidney disease. Here, we detected the circulating TFH cells from 57 IgAN patients and found that the frequency of TFH cells was increased in IgA nephropathy patients with renal TLS and also increased in renal tissues from the ischemic-reperfusion-injury (IRI)-induced TLS model. The inducible T-cell co-stimulator (ICOS) is one of the surface marker molecules of TFH. Remarkably, the application of an ICOS-neutralizing antibody effectively prevented the upregulation of TFH cells and expression of its canonical functional mediator IL-21, and also reduced renal TLS formation and renal fibrosis in IRI mice in vivo. In the study of this mechanism, we found that recombinant IL-21 could directly promote renal fibrosis and the expression of p65. Furthermore, BAY 11-7085, a p65 selective inhibitor, could effectively alleviate the profibrotic effect induced by IL-21 stimulation. Our results together suggested that TFH cells contribute to TLS formation and renal fibrosis by IL-21. Targeting the ICOS-signaling pathway network could reduce TFH cell infiltration and alleviate renal fibrosis.

A skewed ratio of free light chains is more common in patients with late-onset than early-onset myasthenia gravis

Myasthenia gravis (MG) is an autoantibody-mediated neuromuscular disease with an unpredictable clinical course. Serum free light chains (FLCs) have risen as a promising biomarker for MG, but their role in different subtypes of MG and in predicting disease progression is still uncharted.We investigated plasma from 58 generalized MG patients during post-thymectomy follow-up to determine κ and λ FLC and κ/λ ratio. In a subcohort of 30 patients, we examined the expression of 92 proteins associated with immuno-oncology using Olink. We further studied the ability of FLCs or proteomic markers to differentiate disease severity.Patients with late-onset MG (LOMG) displayed significantly higher mean κ/λ ratio than patients with early-onset MG (P = 0.004). Inducible T-cell co-stimulator ligand (ICOSLG), matrix metalloproteinase 7 (MMP7), hepatocyte growth factor (HGF), and arginase 1 (ARG1) were differentially expressed in MG patients compared to healthy controls. There were no significant associations between clinical outcomes and FLCs or the assayed proteins.In conclusion, an elevated κ/λ ratio suggests long-lasting aberrant clonal plasma cell function in LOMG. Immuno-oncology-related proteomic analysis showed alterations in immunoregulatory pathways. Our findings pinpoint the FLC ratio as a biomarker for LOMG and call for further investigation of the immunoregulatory pathways in MG.

ICOS gene polymorphisms in systemic lupus erythematosus: A case-control study.

The inducible T-cell costimulator (ICOS) may play an important role in adaptive immunity by regulating the interaction between T cells and antigen-presenting cells. Disruption of this molecule can lead to autoimmune diseases, in particular systemic lupus erythematosus (SLE). In this study, we aimed to explore the possible association between ICOS gene polymorphisms and SLE as well as their influence on disease susceptibility and clinical outcomes. A further objective was to assess the potential impact of these polymorphisms on RNA expression. A case-control study, including 151 patients with SLE, and 291 unrelated healthy controls (HC) matched in gender, and geographical origin, was performed to genotype two polymorphisms located in the ICOS gene: rs11889031 (-693 G/A) and rs10932029 (IVS1+173 T/C); using the polymerase chain reaction (PCR)-restriction fragment length polymorphism method. The different genotypes were validated by direct sequencing. The expression level of ICOS mRNA was assessed by quantitative PCR in peripheral blood mononuclear cells of SLE patients and HC. The results were analysed using Shesis and spss.20. Our results revealed a significant association between ICOS gene rs11889031>CC genotype and SLE disease (codominant genetic model 1, (C/C vs. C/T), p=.001, odds ratio [OR]=2.18 IC [1.36-3.49]); codominant genetic model 2, (C/C vs. T/T) p=.007, OR=15.29 IC [1.97-118.5]); dominant genetic model, (C/C vs. C/T+T/T) p=.0001, OR=2.44 IC [1.53-3.9]). Besides, there was a marginal association between rs11889031>TT genotype and T allele with a protective role from SLE (recessive genetic model, p=.016, OR=0.08 IC [0.01-0.63] and p=7.6904E-05, OR=0.43 IC=[0.28-0.66], respectively). Moreover, statistical analysis indicated that the rs11889031>CC genotype was linked with clinical and serological manifestations of SLE, including blood pressure, and anti-SSA antibodies production in SLE patients. However, the ICOS gene rs10932029 polymorphism was not associated with susceptibility to SLE. On the other side, we did not note any effect of the two selected polymorphisms on the level of ICOS mRNA gene expression. The study showed a significant predisposing association of the ICOS rs11889031>CC genotype with SLE, in contrast to a protective effect of rs11889031>TT genotype in Tunisian patients. Our results suggest that ICOS rs11889031 may act as a risk factor for SLE and could be used as a genetic susceptibility biomarker.

Relationship between ICOS and ICOS ligand RNA expression patterns with tumor type, tumor mutational burden, and clinically relevant immune checkpoints.

e14669 Background: ICOS (inducible T-cell co-stimulator) has a unique ligand (ICOSL). Together they contribute to both antitumor responses/immune stimulation and potentiating immunosuppression. The interaction of ICOS and ICOSL can stimulate CD4 and CD8 ICOS-positive T-cell populations, but also can increase immunosuppressive regulator T-cells. ICOS agonists and antagonists are both under development as novel therapies. We aimed to quantify ICOS and ICOSL expression relationships with tumor type and other clinically relevant checkpoint inhibitors along with evaluating relationships between ICOS and ICOSL expression patterns. Methods: Data from 514 patients with advanced solid tumors at the University of California San Diego were used in the analysis. RNA expression levels of ICOS, ICOS ligand, PD-1, PD-L1, LAG-3, and CTLA-4 from tumor specimens were analyzed at OmniSeq. Tumor mutational burden (TMB) was also evaluated. Univariate analyses (Fischer’s exact tests) and multivariate analysis (logistic regression) were conducted in SAS v 9.4 to determine relationships between high (>=75 percentile RNA rank) and low (0-24 percentile RNA rank) ICOS and ICOSL expression with age, gender, cancer type, high LAG-3, high TMB, high CTLA4, high PD-1, and high PD-L1. The relationship between ICOS and ICOSL high or low expression were also assessed. Results: Seventy patients had high ICOS (14%) and 192 had high ICOSL (37%) while low ICOS was seen in 226 (44%) and low ICOSL was seen in 76 (15%). High ICOS RNA levels were independently associated with patients not having colorectal cancer (p=0.0009), tumors with high PD-1 expression (p=0.025), tumors with high PD-L1 expression (p<0.0001), and tumors with high CTLA-4 expression (p<0.0001). Low ICOS RNA levels were independently associated with patients whose tumors did not have high PD-1 (p=0.0006), tumors that did not have high PD-L1 (p=0.01), tumors that did not have high CTLA-4 expression (p<0.0001), and those with low ICOSL expression (p=0.0007). High ICOSL was independently associated with a diagnosis of colorectal cancer (p=0.0015), tumors that did not have high PD-L1 expression (p=0.003), and tumors with high CTLA4 (p=0.0001). Low ICOSL was independently associated with patients who did not have colorectal cancer (p=0.0001) and tumors with low ICOS expression (p=0.0032). Conclusions: ICOS and ICOSL RNA expression patterns can provide insight into the complicated ICOS/ICOSL immune checkpoint signaling pathway and help support rational immunotherapy combinations as part of a precision medicine approach. Both stimulators and inhibitors of the ICOS/ICOSL axis are being developed, and their proper application may require interrogation of the individual patient’s tumor/environment.

Granulocyte-Macrophage Colony-Stimulating Factor Influence on Soluble and Membrane-Bound ICOS in Combination with Immune Checkpoint Blockade.

With the successful development of immune checkpoint blockade, there remains the continued need to improve efficacy and decrease toxicities. The addition of granulocyte-macrophage colony-stimulating factor (GM-CSF) to ipilimumab has previously demonstrated both an improvement in efficacy and decrease in the incidence of high-grade adverse events. ICOS+CD4+ or ICOS+CD8+ peripheral blood T cells are significantly greater in the patients treated with ipilimumab plus GM-CSF than in the patients treated with ipilimumab alone. To better understand the effects of GM-CSF on inducible T-cell costimulator (ICOS) and clinical outcomes, the relative roles of identified soluble ICOS and membrane-bound ICOS were evaluated. The ICOS splice variant was secreted and found to have immunologic suppressive effects. Changes in soluble ICOS splice variant levels in treated patients correlated with clinical outcomes. GM-CSF enhanced membrane-bound ICOS in an IL12-dependent manner but did not increase soluble ICOS levels. Whereas soluble ICOS plays a role in immune suppression, GM-CSF efficacy involves increasing membrane-bound ICOS and induction of dendritic cell development. Thus, soluble ICOS splice variants may be used as a biomarker for GM-CSF and immune checkpoint blockade-based therapies.

WED-425 - Co-stimulatory signals mediated by inducible T-cell co-stimulator (ICOS) influence the hepatic expansion auto-aggressive CD8+T-cells in non-alcoholic steatohepatitis (NASH)

WED-425 - Co-stimulatory signals mediated by inducible T-cell co-stimulator (ICOS) influence the hepatic expansion auto-aggressive CD8+T-cells in non-alcoholic steatohepatitis (NASH)

Comparative expression analysis of immune-related markers in surgically resected lung neuroendocrine neoplasms

BackgroundAlthough immunotherapy has led to a paradigm shift in the treatment of lung cancer, the therapeutic approaches for lung neuroendocrine neoplasms (LNENs) are still limited. Our aim was to explore the immunological landscape and the expression of immune checkpoint markers in LNENs. MethodsSurgically removed tumor samples of 26 atypical carcinoid (AC), 30 large cell neuroendocrine carcinoma (LCNEC) and 29 small cell lung cancer (SCLC) patients were included. The immune phenotype of each tumor type was assessed by using a panel of 15 immune-related markers. As these markers are potentially expressed by immune cells and/or tumor cells, they might serve as putative targets for immunotherapy. Expression patterns were measured by immunohistochemistry and correlated with clinicopathological parameters and prognosis. ResultsUnsupervised hierarchical clustering revealed distinct immunologic profiles across tumor types. Specifically, AC tumors were characterized by high tumor cell CD40 expression and low levels of immune infiltrates whereas SCLC samples had a high CD47 and Inducible T Cell Costimulator (ICOS) expression in tumor cells and immune cells, respectively. High CD70 and CD137 expression by tumor cells as well as elevated expression of CD27, Lymphocyte Activation Gene 3 (LAG3), and CD40 by immune cells were characteristic for LCNEC samples. Overall, SCLC and LCNEC tumors had a more immunogenic phenotype than AC samples. High tumor cell CD47 and CD40 expressions were associated with impaired and improved survival outcomes, respectively. ConclusionsBy providing insights into the widely divergent immunologic profiles of LNENs, our results might serve as a basis for the development of novel immunotherapy-related approaches in these devastating malignancies.

Reciprocal costimulatory molecules control the activation of mucosal type 3 innate lymphoid cells during engagement with B cells

Innate lymphoid cells (ILCs) are the counterpart of T helper cells in the innate immune system and share multiple phenotypes with T helper cells. Inducible T-cell costimulator (ICOS) is recognized on T cells and participates in T-cell activation and T and B-cell engagement in lymphoid tissues. However, the role of ICOS in ILC3s and ILC3-involved interactions with the immune microenvironment remains unclear. Here, we found that ICOS expression on human ILC3s was correlated with the activated state of ILC3s. ICOS costimulation enhanced the survival, proliferation, and capacity of ILC3s to produce cytokines (IL-22, IL-17A, IFN-γ, TNF, and GM-CSF). Via synergistic effects of ICOS and CD40 signaling, B cells promoted ILC3 functions, and ILC3-induced T-cell-independent B-cell IgA and IgM secretion primarily required CD40 signaling. Hence, ICOS is essential for the nonredundant role of ILC3s and their interaction with adjacent B cells.

Non-Redundant Roles of T Cell Costimulation Pathways in Inflammatory Arthritis Revealed by Dual Blockade of ICOS and CD28 with Acazicolcept (ALPN-101).

CD28 and inducible T cell costimulator (ICOS) appear to have nonredundant roles in T cell activation and adaptive immunity. We undertook this study to characterize in vitro and in vivo the therapeutic potential of acazicolcept (ALPN-101), an Fc fusion protein of a human variant ICOS ligand (ICOSL) domain designed to inhibit both CD28 and ICOS costimulation, in inflammatory arthritis. Acazicolcept was compared in vitro with inhibitors of either the CD28 or ICOS pathways (abatacept and belatacept [CTLA-4Ig], prezalumab [anti-ICOSL monoclonal antibody]) in receptor binding and signaling assays, and in a collagen-induced arthritis (CIA) model. Acazicolcept was also compared in cytokine and gene expression assays of peripheral blood mononuclear cells (PBMCs) from healthy donors or rheumatoid arthritis (RA) or psoriatic arthritis (PsA) patients stimulated with artificial antigen-presenting cells (APCs) expressing CD28 and ICOS ligands*. Acazicolcept bound CD28 and ICOS, prevented ligand binding, and inhibited human T cell functional interactions, matching or exceeding the activity of CD28 or ICOS costimulatory single-pathway inhibitors tested individually or in combination. Acazicolcept administration significantly reduced disease in the CIA model and more potently than abatacept. Acazicolcept also inhibited proinflammatory cytokine production from stimulated PBMCs in cocultures with artificial APCs and demonstrated unique effects on gene expression distinct from those induced by abatacept, prezalumab, or a combination of both. Both CD28 and ICOS signaling play critical roles in inflammatory arthritis. Therapeutic agents such as acazicolcept that coinhibit both ICOS and CD28 signaling may mitigate inflammation and/or disease progression in RA and PsA more effectively than inhibitors of either pathway alone.

Tumor-infiltrating mast cells stimulate ICOS+ regulatory T cells through an IL-33 and IL-2 axis to promote gastric cancer progression

IntroductionIn solid tumors, regulatory T cell (Treg) and mast cell perform different roles depending on the microenvironment. Nevertheless, mast cell and Treg-mediated interactions in gastric cancer (GC) are unclear, as are their regulation, function, and clinical significance. ObjectiveThe present study demonstrated the mechanism of tumor-infiltrating mast cells stimulating ICOS+ regulatory T cells via the IL-33/IL-2 axis to promote the growth of gastric cancer. MethodsAnalyses of 98 patients with GC were conducted to examine mast cell counts, ICOS+ Tregs, and the levels of IL-33 or IL-2. Isolated ICOS+ Treg and CD8+ T cell were stimulated, cultured and tested for their functional abilities in vitro and in vivo. ResultsGC patients exhibited a significantly more production of IL-33 in tumors. Mast cell stimulated by tumor-derived IL-33 exhibited a prolonged lifespan through IL-33 mediated inhibition of apoptosis. Moreover, mast cells stimulated by tumor-derived IL-33 secreted IL-2, which induced Treg expansion. These inducible Tregs displayed an activated immunosuppressive phenotype with positive expression for the inducible T cell co-stimulator (ICOS). In vitro, IL-2 from IL to 33-stimulated mast cells induced increased numbers of ICOS+ Tregs with increased immunosuppressive activity against proliferation and effector function of CD8+ T cell. In vivo, ICOS+ Tregs were treated with anti-IL-2 neutralizing antibody followed by co-injection with CD8+ T cells in GC mouse model, which showed an increased CD8+ T cell infiltration and effector molecules production, meanwhile tumor growth and progression were inhibited. Besides, reduction in GC patient survival was associated with tumor-derived ICOS+ Tregs. ConclusionOur results highlight a crosstalk between GC-infiltrating mast cells and ICOS+ Tregs and provide a novel mechanism describing ICOS+ Treg expansion and induction by an IL-33/mast cell/IL-2 signaling axis in GC, and also provide functional evidence that the modulation of this immunosuppressive pathway can attenuate GC-mediated immune tolerance.

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

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

Systemic Administration of Acazicolcept, a Dual CD28 and Inducible T cell Costimulator Inhibitor, Ameliorates Experimental Autoimmune Uveitis.

Combined inhibition of CD28 and inducible T cell costimulator (ICOS) pathways with acazicolcept (ALPN-101) represents a potential new treatment for uveitis. Here, we evaluate preclinical efficacy using experimental autoimmune uveitis (EAU) in Lewis rats. Efficacy was tested in 57 Lewis rats treated with either systemic (subcutaneous) or local (intravitreal) administration of acazicolcept and compared to treatment with a matched Fc-only control or corticosteroid. Impact of treatment on uveitis was assessed using clinical scoring, optical coherence tomography (OCT), and histology. Ocular effector T cell populations were determined using flow cytometry, and multiplex ELISA used to measure aqueous cytokine concentrations. When compared to Fc control treatment, systemic acazicolcept led to statistically significant decreases in clinical score (P < 0.01), histologic score (P < 0.05), and number of ocular CD45+ cells (P < 0.01). Number of ocular CD4+ and CD8+ T cells expressing IL-17A+ and IFNγ+ were also decreased with statistical significance (P < 0.01). Similar results were achieved with corticosteroids. Intravitreal acazicolcept decreased inflammation scores when compared to untreated fellow eyes and to Fc control treated eyes, although not statistically significant. Systemic toxicity, measured by weight loss, occurred in the corticosteroid-treated, but not in the acazicolcept-treated animals. Systemic treatment with acazicolcept statistically significantly suppressed EAU. Acazicolcept was well-tolerated without the weight loss associated with corticosteroids. Acazicolcept may be an effective alternative to corticosteroids for use in treating autoimmune uveitis. Additional studies are needed to clarify the optimal dose and route for use in humans. We show that T cell costimulatory blockade could be an effective mechanism for treating uveitis.

Aberrant Naive CD4-Positive T Cell Differentiation in Systemic Juvenile Idiopathic Arthritis Committed to B Cell Help.

Systemic juvenile idiopathic arthritis (JIA) features characteristics of autoinflammation and autoimmunity, culminating in chronic arthritis. In this study, we hypothesized that aberrant or incomplete polarization of T helper cells contributes to disease pathology. Cells or serum samples were obtained from healthy controls (n=72) and systemic JIA patients (n=171). Isolated naive T helper cells were cultured under Th1, Th17, and T follicular helper (Tfh) or T peripheral helper (Tph)-polarizing conditions and were partly cocultured with allogenic memory B cells. Cell samples were then analyzed for surface marker, transcription factor, and cytokine expression, as well as plasmablast generation. Serum samples were subjected to multiplexed bead and self-antigen arrays and enzyme-linked immunosorbent assays, and all data were compared to retrospective RNA profiling analyses. Differentiation of systemic JIA-naive T helper cells toward Th1 cells resulted in low expression levels of interferon-γ (IFNγ) and eomesodermin, which was associated in part with disease duration. In contrast, developing Th1 cells in patients with systemic JIA were found to produce elevated levels of interleukin-21 (IL-21), which negatively correlated with cellular expression of IFNγ and eomesodermin. In both in vitro and ex vivo analyses, IL-21 together with programmed cell death 1 (PD-1), inducible T cell costimulator (ICOS), and CXCR5 expression induced naive T helper cells from systemic JIA patients to polarize toward a Tfh/Tph cell phenotype. Retrospective analysis of whole-blood RNA-sequencing data demonstrated that Bcl-6, a master transcription factor in Tfh/Tph cell differentiation, was overexpressed specifically in patients with systemic JIA. Naive T helper cells from systemic JIA patients which were stimulated in vitro promoted B cellular plasmablast generation, and self-antigen array data indicated that IgG reactivity profiles of patients with systemic JIA differed from those of healthy controls. In the pathogenesis of systemic JIA, skewing of naive T helper cell differentiation toward a Tfh/Tph cell phenotype may represent an echo of autoimmunity, which may indicate the mechanisms driving progression toward chronic destructive arthritis.

ICOS/ICOSLG and PD-1 Co-Expression is Associated with the Progression of Colorectal Precancerous- Carcinoma Immune Microenvironment.

This study aimed to investigate the expression of inducible T-cell co-stimulator (ICOS) and its ligand (ICOSLG), along with their association with clinicopathological features and influence on the immune profile in colorectal cancer (CRC). The Cancer Genome Atlas Colorectal Adenocarcinoma cohorts were used. We also analyzed 131 clinical samples of colon lesions, including precancerous lesions (hyperplastic polyps, low-grade dysplasia, and high-grade dysplasia) and CRC tissues. We conducted immunohistochemical (IHC) assays and multiple IHC (mIHC) of CD4+, Foxp3+ tumor-infiltrating lymphocytes (TILs), and PD-1/PD-L1 immune checkpoints in precancerous lesions and CRC samples from our patient subsets to determine changes and correlations in ICOS and ICOSLG expression during progression through the adenoma-carcinoma pathway. High expression of ICOS and ICOSLG was a significant factor in CRC in multiple analyses and was positively correlated with CD4+/Foxp3+ TIL density and PD-1/PD-L1 expression, which increased with the sequential progression of lesions from precancerous tissues to carcinoma. Multivariable logistic regression analysis suggested that the location and expression level of ICOS/ICOSLG may be involved in precancerous-carcinoma progression. The co-expression status of PD-1 and ICOS/ ICOSLG could stratify patients with colorectal lesions into three groups of low, moderate, and high risk of progression. According to this classification and mIHC assays, we found a strong correlation between increased PD-1+ICOS+ or PD-1+ICOSLG+ co-expression and CRC, which might be deemed an independent factor in carcinogenesis. Increased ICOS/ICOSLG expression may be associated with the progressive formation of Foxp3+ TILs in the immune microenvironment and may further promote the development of the abnormal cytology of colorectal lesions from precancerous neoplasia to CRC. Our findings support the interpretation that enhanced co-expression of PD-1+ICOS+ or PD-1+ICOSLG+ contributes to the immune-active microenvironment of the colorectal adenoma-carcinoma sequence.

Targeting the Inducible T-cell Costimulator (ICOS) in Patients with Relapsed/Refractory T-follicular Helper Phenotype Peripheral T-cell and Angioimmunoblastic T-cell Lymphoma.

Proliferation of T-follicular helper (TFH) CD4+ T cells is a postulated pathogenic mechanism for T-cell non-Hodgkin lymphomas (T-NHL). The inducible T-cell costimulator (ICOS) is highly expressed by TFH, representing a potential target. MEDI-570 is a monoclonal antibody against ICOS, which eliminates ICOS+ cells in preclinical models. We report the safety, pharmacokinetics (PK), pharmacodynamics (PD), and clinical activity of MEDI-570 in T-NHL. NCI-9930 is a phase I, first-in-human study of MEDI-570 in relapsed/refractory malignant T-NHL known to express ICOS. MEDI-570 was administered intravenously every 3 weeks for up to 12 cycles. Primary endpoints were safety, dose-limiting toxicities (DLT), and recommended phase II dose (RP2D). Secondary and exploratory endpoints included efficacy parameters and various correlative studies. This study is supported by the National Cancer Institute (NCT02520791). Twenty-three patients were enrolled and received MEDI-570 at five dose levels (0.01-3 mg/kg). Sixteen (70%) had angioimmunoblastic T-cell lymphoma (AITL); median age was 67 years (29-86) and the median prior lines of therapies was 3 (1-16). Most common grade 3 or 4 adverse events were decreased CD4+ T cells (57%), lymphopenia (22%), anemia (13%), and infusion-related reactions (9%). No DLTs were observed. The RP2D was determined at 3 mg/kg. Analysis of T-cell subsets showed reductions in CD4+ICOS+ T cells reflecting its effects on TFH cells. The response rate in AITL was 44%. MEDI-570 was well tolerated and showed promising clinical activity in refractory AITL. MEDI-570 resulted in sustained reduction of ICOS+ T lymphocytes.

Differential Modulation of Human M1 and M2 Macrophage Activity by ICOS-Mediated ICOSL Triggering.

Activated T cells express the inducible T-cell co-stimulator (ICOS) that, upon binding to its ubiquitously expressed ligand (ICOSL), regulates the immune response and tissue repair. We sought to determine the effect of ICOS:ICOSL interaction on human M1 and M2 macrophages. M1 and M2 macrophages were polarized from monocyte-derived macrophages, and the effect of a soluble recombinant form of ICOS (ICOS-CH3) was assessed on cytokine production and cell migration. We show that ICOS-CH3 treatment increased the secretion of CCL3 and CCL4 in resting M1 and M2 cells. In LPS-treated M1 cells, ICOS-CH3 inhibited the secretion of TNF-α, IL-6, IL-10 and CCL4, while it increased that of IL-23. In contrast, M2 cells treated with LPS + IL4 displayed enhanced secretion of IL-6, IL-10, CCL3 and CCL4. In CCL7- or osteopontin-treated M1 cells, ICOS-CH3 boosted the migration rate of M1 cells while it decreased that of M2 cells. Finally, β-Pix expression was upregulated in M1 cells and downregulated in M2 cells by treatment with ICOS-CH3. These findings suggest that ICOSL activation modulates the activity of human M1 and M2 cells, thereby eliciting an overall anti-inflammatory effect consistent with its role in promoting tissue repair.