Targeting the Human T-Cell Inducible COStimulator Molecule with a Monoclonal Antibody Prevents Graft-vs-Host Disease and Preserves Graft vs Leukemia in a Xenograft Murine Model

High dimensional proteomic mapping of bone marrow immune characteristics in immune thrombocytopenia

To investigate the role of co-stimulatory and co-inhibitory molecules on immune tolerance in immune thrombocytopenia (ITP), this study mapped the immune cell heterogeneity in the bone marrow of ITP at the single-cell level using Cytometry by Time of Flight (CyTOF). Thirty-six patients with ITP and nine healthy volunteers were enrolled in the study. As soluble immunomodulatory molecules, more sCD25 and sGalectin-9 were detected in ITP patients. On the cell surface, co-stimulatory molecules like ICOS and HVEM were observed to be upregulated in mainly central memory and effector T cells. In contrast, co-inhibitory molecules such as CTLA-4 were significantly reduced in Th1 and Th17 cell subsets. Taking a platelet count of 30×109 L-1 as the cutoff value, ITP patients with high and low platelet counts showed different T cell immune profiles. Antigen-presenting cells such as monocytes and B cells may regulate the activation of T cells through CTLA-4/CD86 and HVEM/BTLA interactions, respectively, and participate in the pathogenesis of ITP. In conclusion, the proteomic and soluble molecular profiles brought insight into the interaction and modulation of immune cells in the bone marrow of ITP. They may offer novel targets to develop personalized immunotherapies.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Insights into mechanisms of graft-versus-host disease through humanised mouse models

Graft-versus-host disease (GVHD) is a major complication that occurs following allogeneic haematopoietic stem cell transplantation (HSCT) for the treatment of haematological cancers and other blood-related disorders. GVHD is an inflammatory disorder, where the transplanted donor immune cells can mediate an immune response against the recipient and attack host tissues. Despite over 60 years of research, broad-range immune suppression is still used to prevent or treat GVHD, leading to an increased risk of cancer relapse and infection. Therefore, further insights into the disease mechanisms and development of predictive and prognostic biomarkers are key to improving outcomes and reducing GVHD development following allogeneic HSCT. An important preclinical tool to examine the pathophysiology of GVHD and to understand the key mechanisms that lead to GVHD development are preclinical humanised mouse models. Such models of GVHD are now well-established and can provide valuable insights into disease development. This review will focus on models where human peripheral blood mononuclear cells are injected into immune-deficient non-obese diabetic (NOD)-scid-interleukin-2(IL-2)Rγ mutant (NOD-scid-IL2Rγ^null) mice. Humanised mouse models of GVHD can mimic the clinical setting for GVHD development, with disease progression and tissues impacted like that observed in humans. This review will highlight key findings from preclinical humanised mouse models regarding the role of donor human immune cells, the function of cytokines and cell signalling molecules and their impact on specific target tissues and GVHD development. Further, specific therapeutic strategies tested in these preclinical models reveal key molecular pathways important in reducing the burden of GVHD following allogeneic HSCT.

Mice with humanized immune system as novel models to study HIV-associated pulmonary hypertension

People living with HIV and who receive antiretroviral therapy have a significantly improved lifespan, compared to the early days without therapy. Unfortunately, persisting viral replication in the lungs sustains chronic inflammation, which may cause pulmonary vascular dysfunction and ultimate life-threatening Pulmonary Hypertension (PH). The mechanisms involved in the progression of HIV and PH remain unclear. The study of HIV-PH is limited due to the lack of tractable animal models that recapitulate infection and pathobiological aspects of PH. On one hand, mice with humanized immune systems (hu-mice) are highly relevant to HIV research but their suitability for HIV-PH research deserves investigation. On another hand, the Hypoxia-Sugen is a well-established model for experimental PH that combines hypoxia with the VEGF antagonist SU5416. To test the suitability of hu-mice, we combined HIV with either SU5416 or hypoxia. Using right heart catheterization, we found that combining HIV+SU5416 exacerbated PH. HIV infection increases human pro-inflammatory cytokines in the lungs, compared to uninfected mice. Histopathological examinations showed pulmonary vascular inflammation with arterial muscularization in HIV-PH. We also found an increase in endothelial-monocyte activating polypeptide II (EMAP II) when combining HIV+SU5416. Therefore, combinations of HIV with SU5416 or hypoxia recapitulate PH in hu-mice, creating well-suited models for infectious mechanistic pulmonary vascular research in small animals.

Inducible Co-Stimulator (ICOS) in transplantation: A review

Prevention of T cell activation is one of the goals of successful organ and tissue transplantation. Blockade of T cell co-stimulation, particularly of the CD28:B7 interaction, has been shown to prolong graft survival. Inducible Co-Stimulator (ICOS) is the third member of the B7 family and here we review the literature on ICOS, its receptor (B7RP-1), and blockade of this pathway in transplant models. ICOS:B7RP-1 are a single receptor:ligand pair with a loss of function of either being implicated in some autoimmune diseases. ICOS has multiple functions, related to its constitutive expression on B cells and activated T cells. In in vitro transplant models, ICOS:B7RP-1 blockade has produced mixed results as to its ability to modulate lymphocyte proliferation. Several in vivo transplant models demonstrate varying degrees of success in prolonging graft survival. Timing and dose of treatment appear important, and combination with other immunosuppressive treatments may also be of benefit. As ICOS has multiple functions, it may be that the observed variable results are due to inadvertent inactivation of graft protective functions. If these barriers can be overcome, ICOS:B7RP-1 blockade could provide an important target for future immunosuppression regimens.

Daratumumab Prevents Experimental Xenogeneic Graft-Versus-Host Disease by Skewing Proportions of T Cell Functional Subsets and Inhibiting T Cell Activation and Migration

Graft-versus-host disease (GVHD) remains the major cause of mortality and morbidity in non-relapse patients after allogeneic hematopoietic cell transplantation (allo-HCT). As the number of patients undergoing allo-HCT increases, it will become imperative to determine safe and effective treatment options for patients with GVHD, especially those who become refractory to systemic steroid therapy. Daratumumab (Dara), a humanized IgG1 (ĸ subclass) monoclonal antibody targeting the CD38 epitope, is used for the treatment of multiple myeloma. CD38 is a multifunctional ectoenzyme that behaves either as an enzyme, a cell adhesion molecule or a cell surface receptor involved in cell signaling. CD38 is also expressed on various immune effector and suppressor cells. However, the role of CD38 in the immune response remains elusive. We questioned whether CD38 is a potential therapeutic target against alloreactive T cells in the GVHD pathological process. Here, we investigated the impact of Dara on xenogeneic GVHD (xeno-GVHD) and graft-versus-leukemia (GVL) effects in a humanized murine model of transplantation, where human peripheral blood mononuclear cells were adoptively transplanted into immunocompromised NOD.SCID.gc-null (NSG) mice. Mice receiving Dara treatment experienced less weight loss, longer survival and lower GVHD scores compared with those in the control group. Histological evaluations, flow cytometry, RNA-sequencing and RT-qPCR analysis revealed that Dara efficaciously mitigated GVHD through multiple mechanisms including inhibition of the proliferation, activation and differentiation of CD8⁺ cytotoxic T cells, reduced expression of cytotoxic effector molecules, pro-inflammatory cytokines, chemokines and chemoattractant receptors by T cells and promotion of immunosuppressive T cells. More importantly, Dara preserved the GVL effect in a humanized mouse model of leukemia by metabolic reprograming of T cells to promote the induction of Th17, Th1/17and Tc1/17 cells. Our findings indicate that Dara may be an attractive therapeutic option to separate GVHD from GVL effects in patients with hematopoietic malignancies receiving allo-HCT.

Cytotoxic T lymphocyte antigen-4 regulates development of xenogenic graft versus host disease in mice via modulation of host immune responses induced by changes in human T cell engraftment and gene expression

Graft versus host disease (GvHD) is a major clinical problem with a significant unmet medical need. We examined the role of cytotoxic T lymphocyte antigen-4 (CTLA-4) in a xenogenic GvHD (xeno-GvHD) model induced by injection of human peripheral mononuclear cells (hPBMC) into irradiated non-obese diabetic (NOD) SCID gamma (NSG) mice. Targeting the CTLA-4 pathway by treatment with CTLA-4 immunoglobulin (Ig) prevented xeno-GvHD, while anti-CTLA-4 antibody treatment exacerbated the lethality and morbidity associated with GvHD. Xeno-GvHD is associated with infiltration of hPBMCs into the lungs, spleen, stomach, liver and colon and an increase in human proinflammatory cytokines, including interferon (IFN)-γ, tumor necrosis factor (TNF)-α and interleukin (IL)-5. Infiltration of donor cells and increases in cytokines were attenuated by treatment with CTLA-4 Ig, but remained either unaffected or enhanced by anti-CTLA-4 antibody. Further, splenic human T cell phenotyping showed that CTLA-4 Ig treatment prevented the engraftment of human CD45⁺ cells, while anti-CTLA-4 antibody enhanced donor T cell expansion, particularly CD4⁺ (CD45RO⁺ ) subsets, including T box transcription factor TBX21 (Tbet)⁺ CXCR3⁺ and CD25⁺ forkhead box protein 3 (FoxP3) cells. Comprehensive analysis of transcriptional profiling of human cells isolated from mouse spleen identified a set of 417 differentially expressed genes (DEGs) by CTLA-4 Ig treatment and 13 DEGs by anti-CTLA-4 antibody treatment. The CTLA-4 Ig regulated DEGs mapped to down-regulated apoptosis, inflammasome, T helper type 17 (Th17) and regulatory T cell (T_reg ) pathways and enhanced Toll-like receptor (TLR) receptor signaling, TNF family signaling, complement system and epigenetic and transcriptional regulation, whereas anti-CTLA-4 antibody produced minimal to no impact on these gene pathways. Our results show an important role of co-inhibitory CTLA-4 signaling in xeno-GvHD and suggest the therapeutic utility of other immune checkpoint co-inhibitory pathways in the treatment of immune-mediated diseases driven by hyperactive T cells.

GVHD Pathogenesis, Prevention and Treatment: Lessons From Humanized Mouse Transplant Models

Graft-vs-host disease (GVHD) is the most common cause of non-relapse mortality following allogeneic hematopoietic stem cell transplantation (HSCT) despite advances in conditioning regimens, HLA genotyping and immune suppression. While murine studies have yielded important insights into the cellular responses of GVHD, differences between murine and human biology has hindered the translation of novel therapies into the clinic. Recently, the field has expanded the ability to investigate primary human T cell responses through the transplantation of human T cells into immunodeficient mice. These xenogeneic HSCT models benefit from the human T cell receptors, CD4 and CD8 proteins having cross-reactivity to murine MHC in addition to several cytokines and co-stimulatory proteins. This has allowed for the direct assessment of key factors in GVHD pathogenesis to be investigated prior to entering clinical trials. In this review, we will summarize the current state of clinical GVHD research and discuss how xenogeneic HSCT models will aid in advancing the current pipeline of novel GVHD prophylaxis therapies into the clinic.

Cellular and molecular profiling of T-cell subsets at the onset of human acute GVHD

The cellular and molecular processes involved in acute graft-versus-host disease (aGVHD) development early after allogeneic hematopoietic cell transplantation (HCT) in humans remain largely unknown. We have performed multiparameter immunophenotyping and molecular profiling of CD4+ and CD8+ T cells in 2 independent cohorts of patients undergoing HCT, as well as in their HLA-identical sibling donors. Cellular profiling using spectral flow cytometry showed an incomplete reconstitution of the T-cell compartment in recipients without aGVHD early after transplantation, as well as a shift toward an effector memory phenotype, paralleled by depletion of the naive T-cell pool. Molecular profiling of T-cell populations in donors vs recipients without aGVHD revealed increased pathway activity of >40 gene modules in recipients. These pathways were associated in particular with T-cell activation, adhesion, migration, and effector functions. Cellular profiles from recipients developing aGVHD displayed an enrichment of cells with a T memory stem cell-like phenotype compared with recipients without aGVHD. Comparison of gene profiles from these recipients revealed that transforming growth factor-β (TGF-β) signaling was most significantly downregulated, whereas the pathway activity of NF-κB-associated transcription factors and signaling pathways were increased, at aGVHD onset. This study suggests that the integration of cellular and molecular profiles provides new insights into the development of aGVHD in humans.

Targeting co-stimulatory molecules in autoimmune disease

Therapeutic targeting of immune checkpoints has garnered significant attention in the area of cancer immunotherapy, in which efforts have focused in particular on cytotoxic T lymphocyte antigen 4 (CTLA4) and PD1, both of which are members of the CD28 family. In autoimmunity, these same pathways can be targeted to opposite effect: to curb the over-exuberant immune response. The CTLA4 checkpoint serves as an exemplar, whereby CTLA4 activity is blocked by antibodies in cancer immunotherapy and augmented by the provision of soluble CTLA4 in autoimmunity. Here, we review the targeting of co-stimulatory molecules in autoimmune diseases, focusing in particular on agents directed at members of the CD28 or tumour necrosis factor receptor families. We present the state of the art in co-stimulatory blockade approaches, including rational combinations of immune inhibitory agents, and discuss the future opportunities and challenges in this field.

Bendamustine with total body irradiation conditioning yields tolerant T-cells while preserving T-cell-dependent graft-versus-leukemia

Graft-versus-host disease (GvHD) remains a significant impediment to allogeneic hematopoietic cell transplantation (HCT) success, necessitating studies focused on alleviating GvHD, while preserving the graft-versus-leukemia (GvL) effect. Based on our previous studies showing bendamustine with total body irradiation (BEN-TBI) conditioning reduces GvHD compared to the current clinical standard of care cyclophosphamide (CY)-TBI in a murine MHC-mismatched bone marrow transplantation (BMT) model, this study aimed to evaluate the role and fate of donor T-cells following BEN-TBI conditioning. We demonstrate that BEN-TBI reduces GvHD compared to CY-TBI independently of T regulatory cells (Tregs). BEN-TBI conditioned mice have a smaller proportion and less activated donor T-cells, with lower CD47 expression, early post-transplant, but no sustained phenotypic differences in T-cells. In BEN-TBI conditioned mice, donor T-cells gain tolerance specific to host MHC antigens. Though these T-cells are tolerant to host antigens, we demonstrate that BEN-TBI preserves a T-cell-dependent GvL effect. These findings indicate that BEN-TBI conditioning reduces GvHD without compromising GvL, warranting its further investigation as a potentially safer and more efficacious clinical alternative to CY-TBI.

Human Apoptotic Cells, Generated by Extracorporeal Photopheresis, Modulate Allogeneic Immune Response

The induction of specific and sustainable tolerance is a challenging issue in organ transplantation. The discovery of the immunosuppressive properties of apoptotic cells in animal models has paved the way for their use in human transplantation. In this work, we aimed to define a stable, reproducible, and clinically compatible production procedure of human apoptotic cells (Apo-cells). Using a clinically approved extracorporeal photopheresis technique, we have produced and characterized phenotypically and functionally human apoptotic cells. These Apo-cells have immunosuppressive properties proved in vitro and in vivo in NOD/SCID/γC mice by their capacity to modulate an allogeneic response following both a direct and an indirect antigen presentation. These results brought the rationale for the use of Apo-cells in tolerance induction protocol for organ transplantation.

In Vitro Th17-Polarized Human CD4+ T Cells Exacerbate Xenogeneic Graft-versus-Host Disease

Acute graft-versus-host disease (aGVHD) is a severe complication of allogeneic hematopoietic stem cell transplantation. The role of Th17 cells in its pathophysiology remains a matter of debate. In this study, we assessed whether enrichment of human peripheral blood mononuclear cells (PBMCs) with in vitro Th17-polarized CD4⁺ T cells would exacerbate xenogeneic GVHD (xGVHD) into NOD-scid IL-2Rγ null (NSG) mice. Naive human CD4⁺ T cells were stimulated under Th17-skewing conditions for 8 to 10 days and then coinjected in NSG mice with fresh PBMCs from the same donor. We observed that Th17-polarized cells engrafted and migrated toward xGVHD target organs. They also acquired a double-expressing IL-17A⁺IFNγ⁺ profile in vivo. Importantly, cotransfer of Th17-polarized cells (1 × 10⁶) with PBMCs (1 × 10⁶) exacerbated xGVHD compared with transplantation of PBMCs alone (2 × 10⁶). Furthermore, PBMC cotransfer with Th17-polarized cells was more potent for xGVHD induction than cotransfer with naive CD4⁺ T cells stimulated in nonpolarizing conditions (Th0 cells, 1 × 10⁶ + 1 × 10⁶ PBMCs) or with Th1-polarized cells (1 × 10⁶ + 1 × 10⁶ PBMCs). In summary, our results suggest that human Th17-polarized cells can cooperate with PBMCs and be pathogenic in the NSG xGVHD model.

Xenogeneic Graft-Versus-Host Disease in Humanized NSG and NSG-HLA-A2/HHD Mice

Despite the increasing use of humanized mouse models to study new approaches of graft-versus-host disease (GVHD) prevention, the pathogenesis of xenogeneic GVHD (xGVHD) in these models remains misunderstood. The aim of this study is to describe this pathogenesis in NOD/LtSz-Prkdc^scidIL2rγ^tm1Wjl (NSG) mice infused with human PBMCs and to assess the impact of the expression of HLA-A0201 by NSG mice cells (NSG-HLA-A2/HHD mice) on xGVHD and graft-versus-leukemia (GvL) effects, by taking advantage of next-generation technologies. We found that T cells recovered from NSG mice after transplantation had upregulated expression of genes involved in cell proliferation, as well as in TCR, co-stimulatory, IL-2/STAT5, mTOR and Aurora kinase A pathways. T cells had mainly an effector memory or an effector phenotype and exhibited a Th1/Tc1-skewed differentiation. TCRβ repertoire diversity was markedly lower both in the spleen and lungs (a xGVHD target organ) than at infusion. There was no correlation between the frequencies of specific clonotypes at baseline and in transplanted mice. Finally, expression of HLA-A0201 by NSG mice led to more severe xGVHD and enhanced GvL effects toward HLA-A2⁺ leukemic cells. Altogether our data demonstrate that the pathogenesis of xGVHD shares important features with human GVHD and that NSG-HLA-A2/HHD mice could serve as better model to study GVHD and GvL effects.

Inducible Co-Stimulator (ICOS) as a potential therapeutic target for anti-cancer therapy

INTRODUCTION

The recent success of checkpoint-inhibitors in cancer treatment paved the way for the development of new strategies of agonist and antagonist agents against B7 superfamily members. Inducible Co-Stimulator (ICOS), a co-stimulatory receptor for T-cell enhancement, arouses interest. Areas covered: We performed an extensive literature search with PUBMED using the keywords 'ICOS' and 'cancer' to discuss its involvement in oncogenesis, its expression in different malignancies, and its targeting in relevant preclinical studies. We also searched the Clinicaltrials.gov database for recent updates on early phase clinical trials. Expert opinion: ICOS/ICOSL axis has a dual effect and might participate in anti-tumour T cell response as well as a pro-tumour response due to its connection with regulatory T-cells (Tregs) suppressive activity. Therefore, both antagonist and agonist antibodies might be of interest in the targeting ICOS/ICOSL pathway for cancer treatment. In preclinical studies, ICOS agonist monoclonal antibodies (mAbs) have shown to potentiate the effect of inhibitory checkpoint blockade. In contrast, antagonistic anti-ICOS mAbs could not only inhibit lymphoid tumour cells expressing ICOS, but also dampen immunosuppressive Tregs. Two agonist and one antagonist mAbs are evaluated in phase I/II trials. Efficacy, safety, and combination strategies with anti-ICOS agonist or antagonist have yet to be specified.

Antitumor activity of EGFR-specific CAR T cells against non-small-cell lung cancer cells in vitro and in mice

Effective control of non-small-cell lung cancer (NSCLC) remains clinically challenging, especially during advanced stages of the disease. This study developed an adoptive T-cell treatment through expression of a chimeric antigen receptor (CAR) to target human epidermal growth factor receptor (EGFR) in NSCLC. We optimized the non-viral piggyBac transposon system to engineer human T cells for the expression of EGFR-CAR, consisting of EGFR scFv, transmembrane domain, and intracellular 4-1BB-CD3ζ signaling domains. The modified CAR T cells exhibited expansion capability and anticancer efficacy in a time- and antigen-dependent manner in vitro as well as regression of EGFR-positive human lung cancer xenografts in vivo. EGFR-CAR T therapy is a promising strategy to improve the efficacy and potency of the adoptive immunotherapy in NSCLC. Moreover, EGFR-CAR T therapy could become a clinical application for NSCLC patients in the future.

Immune checkpoint molecules in acute myeloid leukaemia: managing the double-edged sword

New immunotherapeutic interventions have revolutionized cancer treatment. The immune responsiveness of acute myeloid leukaemia (AML) was first demonstrated by allogeneic stem cell transplantation. In addition, milder immunotherapeutic approaches are exploited. However, the long-term efficacy of these therapies is hampered by various immune resistance and editing mechanisms. In this regard, co-inhibitory signalling pathways have been shown to play a crucial role. Via up-regulation of inhibitory checkpoints, tumour-reactive T cell and Natural Killer cell responses can be strongly impeded. Accordingly, the introduction of checkpoint inhibitors targeting CTLA-4 (CTLA4) and PD-1 (PDCD1, CD279)/PD-L1 (CD274, PDCD1LG1) accomplished a breakthrough in cancer treatment, with impressive clinical responses. Numerous new co-inhibitory players and novel combination therapies are currently investigated for their potential to boost anti-tumour immunity and improve survival of cancer patients. Although the challenge here remains to avoid severe systemic toxicity. This review addresses the involvement of co-inhibitory signalling in AML immune evasion and discusses the opportunities for checkpoint blockers in AML treatment.