Endogenous CD28 drives CAR T cell responses in multiple myeloma.

Recent FDA approvals of chimeric antigen receptor (CAR) T cell therapy for multiple myeloma (MM) have reshaped the therapeutic landscape for this incurable cancer. In pivotal clinical trials B cell maturation antigen (BCMA) targeted, 4-1BB co-stimulated (BBζ) CAR T cells dramatically outperformed standard-of-care chemotherapy, yet most patients experienced MM relapse within two years of therapy, underscoring the need to improve CAR T cell efficacy in MM. We set out to determine if inhibition of MM bone marrow microenvironment (BME) survival signaling could increase sensitivity to CAR T cells. In contrast to expectations, blocking the CD28 MM survival signal with abatacept (CTLA4-Ig) accelerated disease relapse following CAR T therapy in preclinical models, potentially due to blocking CD28 signaling in CAR T cells. Knockout studies confirmed that endogenous CD28 expressed on BBζ CAR T cells drove in vivo anti-MM activity. Mechanistically, CD28 reprogrammed mitochondrial metabolism to maintain redox balance and CAR T cell proliferation in the MM BME. Transient CD28 inhibition with abatacept restrained rapid BBζ CAR T cell expansion and limited inflammatory cytokines in the MM BME without significantly affecting long-term survival of treated mice. Overall, data directly demonstrate a need for CD28 signaling for sustained in vivo function of CAR T cells and indicate that transient CD28 blockade could reduce cytokine release and associated toxicities.

Targeting CD8+ T cells with natural products for tumor therapy: Revealing insights into the mechanisms.

BACKGROUND: Despite significant advances in cancer immunotherapy over the past decades, such as T cell-engaging chimeric antigen receptor (CAR)-T cell therapy and immune checkpoint blockade (ICB), therapeutic failure resulting from various factors remains prevalent. Therefore, developing combinational immunotherapeutic strategies is of great significance for improving the clinical outcome of cancer immunotherapy. Natural products are substances that naturally exist in various living organisms with multiple pharmacological or biological activities, and some of them have been found to have anti-tumor potential. Notably, emerging evidences have suggested that several natural compounds may boost the anti-tumor effects through activating immune response of hosts, in which CD8+ T cells play a pivotal role. METHODS: The data of this review come from PubMed, Web of Science, Google Scholar, and ClinicalTrials (https://clinicaltrials.gov/) with the keywords "CD8+ T cell", "anti-tumor", "immunity", "signal 1", "signal 2", "signal 3", "natural products", "T cell receptor (TCR)", "co-stimulation", "co-inhibition", "immune checkpoint", "inflammatory cytokine", "hesperidin", "ginsenoside", "quercetin", "curcumin", "apigenin", "dendrobium officinale polysaccharides (DOPS)", "luteolin", "shikonin", "licochalcone A", "erianin", "resveratrol", "procyanidin", "berberine", "usnic acid", "naringenin", "6-gingerol", "ganoderma lucidum polysaccharide (GL-PS)", "neem leaf glycoprotein (NLGP)", "paclitaxel", "source", "pharmacological activities", and "toxicity". These literatures were published between 1993 and 2023. RESULTS: Natural products have considerable advantages as anti-tumor drugs based on the various species, wide distribution, low price, and few side effects. This review summarized the effects and mechanisms of some natural products that exhibit anti-tumor effects via targeting CD8+ T cells, mainly focused on the three signals that activate CD8+ T cells: TCR, co-stimulation, and inflammatory cytokines. CONCLUSION: Clarifying the role and underlying mechanism of natural products in cancer immunotherapy may provide more options for combinational treatment strategies and benefit cancer therapy, to shed light on identifying potential natural compounds for improving the clinical outcome in cancer immunotherapy.

Differential Impact of CD43 and CD28 on T-Cell Differentiation Depending on the Order of Engagement with the TCR.

The combination of signals from the T-cell receptor (TCR) and co-stimulatory molecules triggers transcriptional programs that lead to proliferation, cytokine secretion, and effector functions. We compared the impact of engaging the TCR with CD28 and/or CD43 at different time points relative to TCR engagement on T-cell function. TCR and CD43 simultaneous engagement resulted in higher CD69 and PD-1 expression levels than in TCR and CD28-stimulated cells, with a cytokine signature of mostly effector, inflammatory, and regulatory cytokines, while TCR and CD28-activated cells secreted all categories of cytokines, including stimulatory cytokines. Furthermore, the timing of CD43 engagement relative to TCR ligation, and to a lesser degree that of CD28, resulted in distinct patterns of expression of cytokines, chemokines, and growth factors. Complete cell activation was observed when CD28 or CD43 were engaged simultaneously with or before the TCR, but ligating the TCR before CD43 or CD28 failed to complete a cell activation program regarding cytokine secretion. As the order in which CD43 or CD28 and the TCR were engaged resulted in different combinations of cytokines that shape distinct T-cell immune programs, we analyzed their upstream sequences to assess whether the combinations of cytokines were associated with different sets of regulatory elements. We found that the order in which the TCR and CD28 or CD43 are engaged predicts the recruitment of specific sets of chromatin remodelers and TFSS, which ultimately regulate T-cell polarization and plasticity. Our data underscore that the combination of co-stimulatory molecules and the time when they are engaged relative to the TCR can change the cell differentiation program.

Conversion from calcineurin inhibitors to belatacept-based immunosuppressive therapy skews terminal proliferation of non-classical monocytes and lowers lymphocyte counts.

Belatacept, a modified form of CTLA-Ig that blocks CD28-mediated co-stimulation of T cells, is an immune-suppressant that can be used as an alternative to calcineurin inhibitors (CNIs). In kidney transplant recipients, belatacept has been associated with improved renal function and reduced cardiovascular toxicity. Monocytes as well as T-lymphocytes play causal roles in the pathophysiology of atherosclerotic disease. We hypothesized that the beneficial impact of the use of belatacept over CNIs on cardiovascular risk could be partly explained by the impact of belatacept therapy on these circulating leukocytes. Hence, we phenotyped circulating leukocytes in transplanted patients with a stable renal function that were randomized between either continuation of CNI or conversion to belatacept in two international studies in which we participated. In 41 patients, we found that belatacept-treated patients consistently showed lower numbers of B-lymphocytes, T-lymphocytes as well as CD14-negative monocytes (CD14NM), especially in non-diabetic patients. Our observation that this decrease was associated to plasma concentrations of TNFα is consistent with a model where CD14NM-production of TNFα is diminished by belatacept-treatment, due to effects on the antigen-presenting cell compartment.

The best GVHD prophylaxis: Or at least progress towards finding it.

Options for GVHD prophylaxis after allogeneic hematopoietic cell transplantation can best be chosen by understanding the pathophysiology of GVHD. Interventions to limit T cell activation, expansion and subsequent tissue injury can each be utilized in designing successful GVHD prevention strategies Depleting, tolerizing or blunting T cells or host antigen presenting cells (APCs), blocking co-stimulation or more broadly suppressing inflammation have all been used. Interventions which spare regulatory T cells (Tregs) may prevent GVHD and facilitate controlled allo-responses and not compromise subsequent relapse risks. Graft manipulations and pharmacologic interventions each have potential to limit the morbidity of GVHD while permitting the immunocompetence to prevent infection or relapse.

Case report: Can cochlear implant stimulation lead to improved balance even after vestibular neurectomy?

Introduction: In a previous manuscript from our research group, the concept of vestibular co-stimulation was investigated in adult subjects who received a cochlear implant (CI). Despite what literature reports state, no signs of vestibular co-stimulation could be observed. Results: In this case report, it was described how a woman, who previously underwent a neurectomy of the left vestibular nerve and suffers from bilateral vestibulopathy (BVP), reported improved balance whenever her CI on the left was stimulating. Unexpectedly, the sway analyses during posturography indeed showed a clinically relevant improvement when the CI was activated. Discussion: Vestibular co-stimulation as a side effect of CI stimulation could not be the explanation in this case due to the ipsilateral vestibular neurectomy. It is more likely that the results can be attributed to the electrically restored auditory input, which serves as an external reference for maintaining balance and spatial orientation. In addition, this patient experienced disturbing tinnitus whenever her CI was deactivated. It is thus plausible that the tinnitus increased her cognitive load, which was already increased because of the BVP, leading to an increased imbalance in the absence of CI stimulation.

Applications of Curcumin and Its Nanoforms in the Treatment of Cancer.

Due to the diverse medicinal and pharmacokinetic properties of turmeric, it is well-known in the therapeutic, pharmaceutic, nutraceutical, cosmetic, and dietary industries. It gained importance due to its multitude of properties, such as wound-healing, anti-inflammatory, anti-oxidant, anti-microbial, cytoprotective, anti-aging, anti-cancer, and immunomodulatory effects. Even though the natural healing effect of turmeric has been known to Indians as early as 2500 BCE, the global demand for turmeric has increased only recently. A major reason for the beneficiary activities of turmeric is the presence of the yellow-colored polyphenolic compound called curcumin. Many studies have been carried out on the various properties of curcumin and its derivatives. Despite its low bioavailability, curcumin has been effectively used for the treatment of many diseases, such as cardiovascular and neurological diseases, diabetes, arthritis, and cancer. The advent of nanobiotechnology has further opened wide opportunities to explore and expand the use of curcumin in the medical field. Nanoformulations using curcumin and its derivatives helped to design new treatment modalities, specifically in cancer, because of the better bioavailability and solubility of nanocurcumin when compared to natural curcumin. This review deals with the various applications of curcumin nanoparticles in cancer therapy and broadly tries to understand how it affect the immunological status of the cancer cell.

EGFR-selective activation of CD27 co-stimulatory signaling by a bispecific antibody enhances anti-tumor activity of T cells.

A higher density of tumor infiltrating lymphocytes (TILs) in the tumor microenvironment, particularly cytotoxic CD8+ T cells, is associated with improved clinical outcome in various cancers. However, local inhibitory factors can suppress T cell activity and hinder anti-tumor immunity. Notably, TILs from various cancer types express the co-stimulatory Tumor Necrosis Factor receptor CD27, making it a potential target for co-stimulation and re-activation of tumor-infiltrated and tumor-reactive T cells. Anti-cancer therapeutics based on exploiting CD27-mediated T cell co-stimulation have proven safe, but clinical responses remain limited. This is likely because current monoclonal antibodies fail to effectively activate CD27 signaling, as this receptor requires higher-order receptor cross-linking. Here, we report on a bispecific antibody, CD27xEGFR, that targets both CD27 and the tumor antigen, epidermal growth factor receptor (EGFR). By targeting EGFR, which is commonly expressed on carcinomas, CD27xEGFR induced cancer cell-localized crosslinking and activation of CD27. The design of CD27xEGFR includes an Fc-silent domain, which is designed to minimize potential toxicity by reducing Fc gamma receptor-mediated binding and activation of immune cells. CD27xEGFR bound to both of its targets simultaneously and triggered EGFR-restricted co-stimulation of T cells as measured by T cell proliferation, T cell activation markers, cytotoxicity and IFN-γ release. Further, CD27xEGFR augmented T cell cytotoxicity in a panel of artificial antigen-presenting carcinoma cell line models, leading to Effector-to-Target ratio-dependent elimination of cancer cells. Taken together, we present the in vitro characterization of a novel bispecific antibody that re-activates T cell immunity in EGFR-expressing cancers through targeted co-stimulation of CD27.

Shining a LIGHT on myeloid cell targeted immunotherapy.

Despite over a decade of clinical trials combining inhibition of emerging checkpoints with a PD-1/L1 inhibitor backbone, meaningful survival benefits have not been shown in PD-1/L1 inhibitor resistant or refractory solid tumours, particularly tumours dominated by a myelosuppressive microenvironment. Achieving durable anti-tumour immunity will therefore likely require combination of adaptive and innate immune stimulation, myeloid repolarisation, enhanced APC activation and antigen processing/presentation, lifting of the CD47/SIRPα (Cluster of Differentiation 47/signal regulatory protein alpha) 'do not eat me' signal, provision of an apoptotic 'pro-eat me' or 'find me' signal, and blockade of immune checkpoints. The importance of effectively targeting mLILRB2 and SIRPAyeloid cells to achieve improved response rates has recently been emphasised, given myeloid cells are abundant in the tumour microenvironment of most solid tumours. TNFSF14, or LIGHT, is a tumour necrosis superfamily ligand with a broad range of adaptive and innate immune activities, including (1) myeloid cell activation through Lymphotoxin Beta Receptor (LTßR), (2) T/NK (T cell and natural killer cell) induced anti-tumour immune activity through Herpes virus entry mediator (HVEM), (3) potentiation of proinflammatory cytokine/chemokine secretion through LTßR on tumour stromal cells, (4) direct induction of tumour cell apoptosis in vitro, and (5) the reorganisation of lymphatic tissue architecture, including within the tumour microenvironment (TME), by promoting high endothelial venule (HEV) formation and induction of tertiary lymphoid structures. LTBR (Lymphotoxin beta receptor) and HVEM rank highly amongst a range of costimulatory receptors in solid tumours, which raises interest in considering how LIGHT-mediated costimulation may be distinct from a growing list of immunotherapy targets which have failed to provide survival benefit as monotherapy or in combination with PD-1 inhibitors, particularly in the checkpoint acquired resistant setting.

Delivering co-stimulatory tumor necrosis factor receptor agonism for cancer immunotherapy: past, current and future perspectives.

The tumor necrosis factor superfamily (TNFSF) and their receptors (TNFRSF) are important regulators of the immune system, mediating proliferation, survival, differentiation, and function of immune cells. As a result, their targeting for immunotherapy is attractive, although to date, under-exploited. In this review we discuss the importance of co-stimulatory members of the TNFRSF in optimal immune response generation, the rationale behind targeting these receptors for immunotherapy, the success of targeting them in pre-clinical studies and the challenges in translating this success into the clinic. The efficacy and limitations of the currently available agents are discussed alongside the development of next generation immunostimulatory agents designed to overcome current issues, and capitalize on this receptor class to deliver potent, durable and safe drugs for patients.

What do we know about co-stimulatory and co-inhibitory immune checkpoint signals in ankylosing spondylitis?

Ankylosing spondylitis is the main entity of a family of inflammatory diseases affecting many musculoskeletal (sacroiliac joints, spine, and peripheral joints) and extra-musculoskeletal sites, termed spondyloarthritis. While it is debated whether disease onset is primarily driven by autoimmune or autoinflammatory processes, what is certain is that both innate and adaptive immune responses orchestrate local and systemic inflammation, which leads to chronic pain and immobility. Immune checkpoint signals are one key player in keeping the immune system in check and in balance, but their role in disease pathogenesis is still rather elusive. Therefore, we ran a MEDLINE search utilizing the PubMed platform for a variety of immune checkpoint signals in regard to ankylosing spondylitis. In this review, we summarize the experimental and genetic data available and evaluate the relevance of immune checkpoint signalling in the pathogenesis of ankylosing spondylitis. Markers such as PD-1 and CTLA-4 have been extensively studied and facilitate the concept of an impaired negative immune regulation in ankylosing spondylitis. Other markers are either neglected completely or insufficiently examined, and the data is conflicting. Still, some of those markers remain interesting targets to decipher the pathogenesis of ankylosing spondylitis and to develop new treatment strategies.

Antithymocyte Globulin Inhibits CD8+ T Cell Effector Functions via the Paracrine Induction of PDL-1 on Monocytes.

BACKGROUND: Antithymocyte globulins (ATG) are T cell-depleting antibodies used in solid organ transplantation for induction therapy in sensitized patients with a high risk of graft rejection. Previously described effects besides the depletion of T cells have suggested additional modes of action and identified further cellular targets. METHODS: We examined the transcriptional changes arising in immune cells from human blood after ex vivo stimulation with ATG at the single-cell level to uncover additional mechanisms by which ATG regulates T cell activity and effector functions. FINDINGS: Analysis of the paracrine factors present in the plasma of ATG-treated whole blood revealed high levels of chemokines and cytokines, including interferon-γ (IFN-γ). Furthermore, we identified an increase in the surface expression of the programmed death ligand 1 (PDL-1) on monocytes mediated by the released paracrine factors. In addition, we showed that this induction is dependent on the activation of JAK/STAT signaling via the binding of IFN-γ to interferon-γ receptor 1 (IFN-γR1). Lastly, we demonstrated that the modulation of the immune regulatory axis of programmed cell death protein 1 (PD1) on activated CD8+ T cells with PDL-1 found on monocytes mediated by ATG potently inhibits effector functions including the proliferation and granzyme B release of activated T cells. INTERPRETATION: Together, our findings represent a novel mode of action by which ATG exerts its immunosuppressive effects.

CD28-CAR-T cell activation through FYN kinase signaling rather than LCK enhances therapeutic performance.

Signal transduction induced by chimeric antigen receptors (CARs) is generally believed to rely on the activity of the SRC family kinase (SFK) LCK, as is the case with T cell receptor (TCR) signaling. Here, we show that CAR signaling occurs in the absence of LCK. This LCK-independent signaling requires the related SFK FYN and a CD28 intracellular domain within the CAR. LCK-deficient CAR-T cells are strongly signaled through CAR and have better in vivo efficacy with reduced exhaustion phenotype and enhanced induction of memory and proliferation. These distinctions can be attributed to the fact that FYN signaling tends to promote proliferation and survival, whereas LCK signaling promotes strong signaling that tends to lead to exhaustion. This non-canonical signaling of CAR-T cells provides insight into the initiation of both TCR and CAR signaling and has important clinical implications for improvement of CAR function.

CD8+ T cell activation in cancer comprises an initial activation phase in lymph nodes followed by effector differentiation within the tumor.

Improvements in tumor immunotherapies depend on better understanding of the anti-tumor T cell response. By studying human tumor-draining lymph nodes (TDLNs), we found that activated CD8+ T cells in TDLNs shared functional, transcriptional, and epigenetic traits with TCF1+ stem-like cells in the tumor. The phenotype and TCR overlap suggested that these TDLN cells were precursors to tumor-resident stem-like CD8+ T cells. Murine tumor models revealed that tumor-specific CD8+ T cells were activated in TDLNs but lacked an effector phenotype. These stem-like cells migrated into the tumor, where additional co-stimulation from antigen-presenting cells drove effector differentiation. This model of CD8+ T cell activation in response to cancer is different from that of canonical CD8+ T cell activation to acute viruses, and it proposes two stages of tumor-specific CD8+ T cell activation: initial activation in TDLNs and subsequent effector program acquisition within the tumor after additional co-stimulation.

Antigen-presenting T cells provide critical B7 co-stimulation for thymic iNKT cell development via CD28-dependent trogocytosis.

Invariant natural killer T (iNKT) cell development in the thymus depends on T cell receptor recognition of CD1d ligand on CD4/CD8 double-positive thymocytes. We previously reported that B7-CD28 co-stimulation is required for thymic iNKT cell development, but the cellular and molecular mechanisms underlying this co-stimulatory requirement are not understood. Here we report that CD28 expression on CD1d-expressing antigen-presenting T cells is required for thymic iNKT cell development. Mechanistically, antigen-presenting T cells provide co-stimulation through an unconventional mechanism, acquiring B7 molecules via CD28-dependent trogocytosis from B7-expressing thymic epithelial cells, dendritic cells, and B cells and providing critical B7 co-stimulation to developing iNKT cells. Thus, the present study demonstrates a mechanism of B7 co-stimulation in thymic T cell development by antigen-presenting T cells.

OX40 agonist stimulation increases and sustains humoral and cell-mediated responses to SARS-CoV-2 protein and saRNA vaccines.

To prevent SARS-CoV-2 infections and generate long-lasting immunity, vaccines need to generate strong viral-specific B and T cell responses. Previous results from our lab and others have shown that immunizations in the presence of an OX40 agonist antibody lead to higher antibody titers and increased numbers of long-lived antigen-specific CD4 and CD8 T cells. Using a similar strategy, we explored the effect of OX40 co-stimulation in a prime and boost vaccination scheme using an adjuvanted SARS-CoV-2 spike protein vaccine in C57BL/6 mice. Our results show that OX40 engagement during vaccination significantly increases long-lived antibody responses to the spike protein. In addition, after immunization spike protein-specific proliferation was greatly increased for both CD4 and CD8 T cells, with enhanced, spike-specific secretion of IFN-γ and IL-2. Booster (3rd injection) immunizations combined with an OX40 agonist (7 months post-prime) further increased vaccine-specific antibody and T cell responses. Initial experiments assessing a self-amplifying mRNA (saRNA) vaccine encoding the spike protein antigen show a robust antigen-specific CD8 T cell response. The saRNA spike-specific CD8 T cells express high levels of GrzmB, IFN-γ and TNF-α which was not observed with protein immunization and this response was further increased by the OX40 agonist. Similar to protein immunizations the OX40 agonist also increased vaccine-specific CD4 T cell responses. In summary, this study compares and contrasts the effects and benefits of both protein and saRNA vaccination and the extent to which an OX40 agonist enhances and sustains the immune response against the SARS-CoV-2 spike protein.

Co-Stimulatory Receptor Signaling in CAR-T Cells.

T cell engineering strategies have emerged as successful immunotherapeutic approaches for the treatment of human cancer. Chimeric Antigen Receptor T (CAR-T) cell therapy represents a prominent synthetic biology approach to re-direct the specificity of a patient's autologous T cells toward a desired tumor antigen. CAR-T therapy is currently FDA approved for the treatment of hematological malignancies, including subsets of B cell lymphoma, acute lymphoblastic leukemia (ALL) and multiple myeloma. Mechanistically, CAR-mediated recognition of a tumor antigen results in propagation of T cell activation signals, including a co-stimulatory signal, resulting in CAR-T cell activation, proliferation, evasion of apoptosis, and acquisition of effector functions. The importance of including a co-stimulatory domain in CARs was recognized following limited success of early iteration CAR-T cell designs lacking co-stimulation. Today, all CAR-T cells in clinical use contain either a CD28 or 4-1BB co-stimulatory domain. Preclinical investigations are exploring utility of including additional co-stimulatory molecules such as ICOS, OX40 and CD27 or various combinations of multiple co-stimulatory domains. Clinical and preclinical evidence implicates the co-stimulatory signal in several aspects of CAR-T cell therapy including response kinetics, persistence and durability, and toxicity profiles each of which impact the safety and anti-tumor efficacy of this immunotherapy. Herein we provide an overview of CAR-T cell co-stimulation by the prototypical receptors and discuss current and emerging strategies to modulate co-stimulatory signals to enhance CAR-T cell function.

V-set domain containing T-cell activation inhibitor-1 (VTCN1): A potential target for the treatment of autoimmune diseases.

Autoimmunity eventuates when the immune system attacks self-molecules as a result of the breakdown in immune tolerance. Targeting autoimmune diseases via immunomodulation has become an essential strategy in today's era. A B7 superfamily member immune checkpoint, the V-set domain containing T-cell activation inhibitor-1 (VTCN1), also known as B7-H4, B7S1, and B7x, is involved in negatively regulating T-cell activation. VTCN1 transcript has been reported in various lymphoid and non-lymphoid tissues, but its protein expression is restricted, indicating its translational regulation. Dysregulation of VTCN1 has resulted in the exacerbation of various autoimmune diseases. Moreover, increased soluble form of VTCN1 in the patient's sera positively correlates with the disease progression and severity. The current review summarizes all the reports till date, unfolding the role of VTCN1 in various autoimmune diseases and its therapeutic potential.