Inhibit T-cell Activation Research Articles

Photobiomodulation suppresses allergic contact dermatitis by inhibiting T-cell activation.

Allergic contact dermatitis (ACD) is a dermal inflammatory disease caused by allergic reactions to substances that contact the skin. The hyperactivation of T cells plays an important role in its pathogenesis. Photobiomodulation (PBM) is an efficacious therapeutic approach for suppressing inflammatory diseases. This study aimed to evaluate the potentially beneficial role of PBM in ACD models and investigate its possible mechanisms. In this study, the ACD model of C57BL/6 mice was produced and treated with PBM, and the number of T cells was evaluated. In an in vitro study, naïve T cells were isolated and intervened with PBM. The markers of T cell activation were detected by flow cytometer. Transforming growth factor-β (TGF-β) and reactive oxygen species (ROS) were detected to investigate the mechanism. PBM effectively inhibited the inflammatory response by impeding the number of T cells in the ACD model. And in vitro studies showed that PBM could directly moderate the activation of naïve T cells and possess the capability to impede T cell activation via TGF-beta signaling pathway. Our finding elucidates the potential mechanism underlying the inhibitory effects of PBM in inflammatory diseases and furnishes a theoretical foundation for its clinical application.

6489 Type 1 Diabetes Mellitus And Multiple Sclerosis: A Case Report Showing The Concurrent Association Of Two Autoimmune Diseases

Abstract Disclosure: P.B. Singh: None. B. Sabates: None. A. Sharifzadeh: None. R.F. Rodriguez: None. Introduction: Both Type 1 Diabetes Mellitus (T1DM) and Multiple Sclerosis (MS) represent persistent autoimmune conditions. T1DM is characterized by the presence of specific autoantibodies targeting pancreatic β-cells. In MS, autoreactive cells mediate a demyelinating inflammatory response directed against the central nervous system. Despite differences in demographics and clinical characteristics, their common root in autoimmunity has led researchers to discover commonalities in genetic, environmental and immunological features. Case Presentation We present a case of a 40-year-old female with medical history of T1DM diagnosed at 7 years of age and MS diagnosed at 32 years of age. She presented to the hospital with clinical features of optic neuritis and symptoms of squeezing ribcage pressure consistent with acute MS exacerbation. After confirmatory neuroimaging, high-dose intravenous corticosteroids were initiated, and Endocrinology services were consulted for inpatient glycemic management. As the patient’s diabetes was treated via continuous subcutaneous insulin infusion (CSII), her pump settings were adjusted to maintain euglycemia during hospitalization. This case is reported to highlight and discuss the association between T1DM and MS. Discussion About 4-5% of the general population is affected by autoimmune disorders, among which T1DM and MS comprise a substantial portion. Multiple studies demonstrate the association and shared etiopathogenesis between T1DM and MS. One study revealed that the prevalence of T1DM is five times higher in patients with MS in comparison to the general population. In another prospective cohort study, individuals with T1DM had a three times higher chance of subsequently developing MS. Additionally, first-degree relatives of MS patients had a roughly 40% higher risk of developing T1DM. Women with T1DM had a 20-fold higher risk of having MS than women without the condition, per another study. As T-cell mediated autoimmune disorders, both T1DM and MS are characterized by autoantigen specific T1-helper cell responses, decreased T-cell suppressor activity, and the presence of various autoantibodies, some of which are seen in both diseases. One study showed that autoreactive T cells could target both pancreatic islet and central nervous system autoantigens in patients with MS, patients with T1DM, and relatives of patients with T1DM. Since MS- and T1DM-associated HLA haplotypes differ between populations, HLA class II alleles per se may not alone be responsible for disease susceptibility. It is suggested that variation at other non-HLA class II loci and/or unknown environmental factors might contribute significantly to the co-occurrence of these 2 diseases. In conclusion, individuals who already have one autoimmune condition are more likely to have other autoimmune conditions, with T1DM and MS being associated more often than expected. Presentation: 6/2/2024

Matrix stiffening from collagen fibril density and alignment modulates YAP-mediated T-cell immune suppression

T-cells are essential components of the immune system, adapting their behavior in response to the mechanical environments they encounter within the body. In pathological conditions like cancer, the extracellular matrix (ECM) often becomes stiffer due to increased density and alignment of collagen fibrils, which can have a significant impact on T-cell function. In this study, we explored how these ECM properties—density and fibrillar alignment—affect T-cell behavior using three-dimensional (3D) collagen matrices that mimic these conditions. Our results show that increased matrix stiffness, whether due to higher density or alignment, significantly suppresses T-cell activation, reduces cytokine production, and limits proliferation, largely through enhanced YAP signaling. Individually, matrix alignment appears to lower actin levels in activated T-cells and changes migration behavior in both resting and activated T-cells, an effect not observed in matrices with randomly oriented fibrils. Notably, inhibiting YAP signaling was able to restore T-cell activation and improve immune responses, suggesting a potential strategy to boost the effectiveness of immunotherapy in stiff ECM environments. Overall, this study provides new insights into how ECM characteristics influence T-cell function, offering potential avenues for overcoming ECM-induced immunosuppression in diseases such as cancer.

Abstract 52: HIV-derived Proteins Induce Neuroinflammation, Hypertension, and Sympatho-activation via T cell-dependent mechanisms in the Tg26 Mouse Model

Combination antiretroviral therapy (cART) has extended life expectancy in people living with HIV (PLWH), shifting the primary cause of death to cardiovascular disease (CVD). Hypertension affects over 65% of PLWH. However, the mechanisms underlying HIV-associated hypertension remain poorly understood. In PLWH on cART, T cells persist as viral reservoirs, secreting viral proteins that circulate and localize in the central nervous system (CNS). Here, we used theTg26 mouse model, clinically relevant to cART-controlled PLWH, to test the hypothesis that HIV-derived proteins elevate blood pressure (BP) and induce sympatho-activation through blood-brain barrier disruption, microglial activation, and neuroinflammation. Telemetry-based BP measurements revealed a hypertensive phenotype in male and female Tg26 mice (male: WT=112.3 ±1.3 vs. Tg26=121.9 ±4.0 mmHg; female: WT=110.6 ±3.01 vs. Tg26=120.3 ±6.9 mmHg). Tg26 mice displayed increased sympathetic contribution to BP, indicated by a larger BP decrease following ganglionic blockade compared to WT, with no changes in heart rate responses to muscarinic and β-adrenergic receptor blockade, suggesting increased neurogenic BP regulation. Tg26 mice also showed increased aortic vasoconstriction to phenylephrine (P<0.05). LC/MS analysis revealed no significant differences in circulating catecholamine and metabolites between WT and Tg26 mice (n=5). MRI-based brain perfusion measurements also showed no significant differences, indicating an alteration in brain perfusion is not responsible for increased sympathetic activation. Inhibiting T-cell activation using abatacept, a CTLA-4-Ig fusion protein, significantly reduced BP, sympatho-activation, and phenylephrine-induced vasoconstriction in Tg26 mice (n=5, p<0.05). We analyzed the brains of Tg26 mice to investigate how T cells promote hypertension and sympatho-activation. Quantitative PCR confirmed viral protein expression in brain tissues and microglia of Tg26 mice, associated with increased markers of neuroinflammation, microglia activation, and T-cell infiltration (fold change>1.5, n=6, p<0.05). Tg26 mice also showed increased expression of NADPH oxidases and matrix metalloproteinase. However, there were no changes in the expression of tight junction proteins. Our data suggest that the expression of HIV-derived proteins in Tg26 mice induces central inflammation and T cell infiltration, leading to sympatho-activation through T cell-dependent mechanisms.

Persistent tailoring of MSC activation through genetic priming

Mesenchymal stem/stromal cells (MSCs) are an attractive platform for cell therapy due to their safety profile and unique ability to secrete broad arrays of immunomodulatory and regenerative molecules. Yet, MSCs are well known to require preconditioning or priming to boost their therapeutic efficacy. Current priming methods offer limited control over MSC activation, yield transient effects, and often induce the expression of pro-inflammatory effectors that can potentiate immunogenicity. Here, we describe a genetic priming method that can both selectively and sustainably boost MSC potency via the controlled expression of the inflammatory-stimulus-responsive transcription factor interferon response factor 1 (IRF1). MSCs engineered to hyper-express IRF1 recapitulate many core responses that are accessed by biochemical priming using the proinflammatory cytokine interferon-γ (IFN-γ). This includes the upregulation of anti-inflammatory effector molecules and the potentiation of MSC capacities to suppress Tcell activation. However, we show that IRF1-mediated genetic priming is much more persistent than biochemical priming and can circumvent IFN-γ-dependent expression of immunogenic MHC class II molecules. Together, the ability to sustainably activate and selectively tailor MSC priming responses creates the possibility of programming MSC activation more comprehensively for therapeutic applications.

The impact of the expression level of growth differentiation factor 15 in tumor tissue on the response to immunotherapy in non-small cell lung cancer

BackgroundGrowth differentiation factor-15 (GDF-15), a member of the TGF-β superfamily, is overexpressed in various cancers and facilitates immune evasion by inhibiting T-cell activation. GDFATHER-TRIAL’s phase 2a results demonstrated promising outcomes when combining the GDF-15 neutralizing antibody visugromab (CTL002) with nivolumab, enhancing the response to immunotherapy. This study evaluated the prognostic significance of GDF-15 expression in non-small cell lung cancer (NSCLC) tumor tissues in terms of immunotherapy response.MethodsThis retrospective study included 50 patients with metastatic NSCLC treated with nivolumab at Gazi University Hospital between January 2021 and July 2023. GDF-15 expression was evaluated using immunochemistry staining and categorized based on the intensity of cytoplasmic or membranous staining. Samples were divided into a low expression group (scores 0 and 1) and a high expression group (scores 2 and 3). The primary outcomes were progression-free survival (PFS) and overall survival (OS), which were analyzed using Kaplan‒Meier and Cox proportional hazards models. Objective response rates were assessed in secondary outcomes.ResultsOf the 50 patients, 43 were men (86%), with a median age of 63.9 years. Half of the patients exhibited low GDF-15 expression. High GDF-15 expression correlated with shorter PFS and OS. The median PFS was 7.8 months for the low-expression group versus 4.4 months for the high-expression group (HR, 0.41; 95% CI, 0.20–0.83; p = 0.013). The median OS was 18.1 months for the low-expression group compared to 11.8 months for the high-expression group (HR, 0.36; 95% CI, 0.16–0.78; p = 0.007). The objective response rate was significantly greater in the low GDF-15 group (52%) than in the high GDF-15 group (24%) (p = 0.040).ConclusionElevated GDF-15 expression in NSCLC tumor tissues is associated with poorer response to nivolumab, suggesting that GDF-15 is a potential prognostic biomarker for immunotherapy efficacy. These findings warrant further validation through prospective studies to optimize treatment strategies for NSCLC patients.

Direct effects of heroin and methadone on T cell function

Opioid addiction presents a relevant health challenge, with chronic heroin use linked to detrimental effects on various aspects of physical, mental, and sociological health. Opioid maintenance therapy (OMT), particularly using methadone, is the primary treatment option for heroin addiction. Previous studies using blood samples from current heroin addicts and OMT patients have shown immunomodulatory effects of heroin and methadone on T cell function. However, various additional factors beyond heroin and methadone affect these results, including the consumption of other substances, a stressful lifestyle, comorbid psychological and somatic disorders, as well as additional medications. Therefore, we here investigated the direct effects of heroin and methadone on purified human T cells in vitro. Our results reveal that both, heroin and methadone directly suppress Tcell activation and proliferation. Strikingly, this inhibitory effect was markedly stronger in the presence of methadone, correlating with a decrease in secretion of pro-inflammatory cytokines. While heroin did not interfere with the in vitro differentiation and expansion of regulatory Tcells (Tregs), methadone significantly impaired the proliferation of Tregs. Overall, our findings suggest a direct inhibitory impact of both opioids on effector T cell function in vitro, with methadone additionally interfering with Treg induction and expansion in contrast to heroin.

Daphnetin alleviates allergic airway inflammation by inhibiting T-cell activation and subsequent JAK/STAT6 signaling

Allergic asthma is a major health burden on society as a chronic respiratory disease characterized by inflammation and muscle tightening around the airways in response to inhaled allergens. Daphne kiusiana Miquel is a medicinal plant that can suppress allergic airway inflammation; however, its specific molecular mechanisms of action are unclear. In this study, we aimed to elucidate the mechanisms by which D. kiusiana inhibits allergic airway inflammation. We evaluated the anti-inflammatory effects of the ethyl acetate (EA) fraction of D. kiusiana and its major compound, daphnetin, on murine T lymphocyte EL4 cells stimulated with phorbol 12-myristate 13-acetate and ionomycin in vitro and on asthmatic mice stimulated with ovalbumin in vivo. The EA fraction and daphnetin inhibited T-helper type 2 (Th2) cytokine secretion, serum immunoglobulin E production, mucus secretion, and inflammatory cell recruitment in vivo. In vitro, daphnetin suppressed intracellular Ca2+ mobilization (a critical regulator of nuclear factor of activated T cells) and functions of the activator protein 1 transcription factor to reduce interleukin (IL)-4 and IL-13 expression. Daphnetin effectively suppressed the IL-4/-13-induced activation of Janus kinase (JAK)/signal transducer and activator of transcription 6 (STAT6) signaling in vitro and in vivo, thereby inhibiting the expression of GATA3 and PDEF, two STAT6-target genes responsible for producing Th2 cytokines and mucins. These findings indicate that daphnetin suppresses allergic airway inflammation by stabilizing intracellular Ca2+ levels and subsequently inactivating the JAK/STAT6/GATA3/PDEF pathway, suggesting that daphnetin is a promising alternative to existing asthma treatments.

Targeting exhausted cytotoxic T cells through CTLA-4 inhibition promotes elimination of neoplastic cells in human myelofibrosis xenografts.

Myeloproliferative neoplasms represent a group of clonal hematopoietic disorders of which myelofibrosis (MF) is the most aggressive. In the context of myeloid neoplasms, there is a growing recognition of the dysregulation of immune response and T-cell function as significant contributors to disease progression and immune evasion. We investigated cytotoxic T-cell exhaustion in MF to restore immune response against malignant cells. Increased expression of inhibitory receptors like CTLA-4 was observed on cytotoxic T cells from MF patients together with a reduced secretion of IFNɣ and TNFɑ. CTLA-4 ligands CD80 and CD86 were increased on MF granulocytes and monocytes highlighting a possible role for myeloid cells in suppressing T-cell activation in MF patients. Unlike healthy donors, the activation of cytotoxic T cells from MF patients was attenuated in the presence of myeloid cells and restored when T cells were cultured alone or treated with anti-CTLA-4. Moreover, anti-CTLA-4 treatment promoted elimination of neoplastic monocytes and granulocytes in a co-culture system with cytotoxic T cells. To test CTLA-4 inhibition in vivo, patient-derived xenografts were generated by transplanting MF CD34+ cells and by infusing homologous T cells in NSGS mice. CTLA-4 blockade reduced human myeloid chimerism and led to T-cell expansion in spleen and bone marrow. Overall, these findings shed light on T-cell dysfunction in MF and suggest that CTLA-4 blockade can boost the cytotoxic T cell-mediated immune response against tumor cells.

A novel B7-H3 x CD3 bispecific T-cell engager for the treatment of B7-H3+ tumors.

e14509 Background: B7-H3 (CD276) is a transmembrane protein highly expressed in solid tumors but with limited expression in normal tissues. Its presence is strongly associated with the inhibition of T-cell activity, cancer progression, and invasion. Furthermore, B7-H3 is strongly associated with poor prognosis and reduced patient survival. Given its crucial role in tumor biology, B7-H3 has emerged as an attractive therapeutic target for drug development. We utilized ExMab heterodimer platform and common light chain technology to develop EX105, a next-generation B7-H3×CD3 bispecific antibody. This innovative T-cell engager exhibits excellent anti-tumor activity in mouse models and good safety profile in NHP tox study. Methods: EX105 was generated using ExMab heterodimer platform and common light chain technology to form a heterodimeric IgG1 structure. Preclinical pharmacology studies, efficacy, and safety were evaluated. Anti-tumor activity study of EX105 includes in vitro T-cell cytotoxicity assays and in vivo PBMC reconstituted xenograft mice models. Preclinical safety evaluation of EX105 was performed through GLP single-dose and repeat-dose tox studies in non-human primates (NHPs). Results: Based on ELISA and FACS analyses, EX105 can bind to both human and cynomolgus monkey B7-H3 and CD3 antigens. Furthermore, SPR data suggest that EX105 exhibits a high affinity to B7-H3 and a much lower affinity to CD3. In consistent with that, EX105 only induced relatively low cytokine release. Nevertheless, EX105 showed a potent in vitro T cell cytotoxicity against B7-H3+ tumor cell lines. The in vivo anti-tumor activity of EX105 was further determined in several tumor xenograft models. Treatment with EX105 resulted in remarkable tumor regression in both “hot” tumor model and “cold” tumor model, indicating its effectiveness across a range of tumor types. Tox study in NHPs showed minimal adverse effects and no liver impairment after EX105 administration, even at high doses. The cytokine release data observed in this study suggests a good safety profile of EX105, with much lower cytokine release compared to other T cell engagers. Conclusions: These findings collectively indicate that EX105 has the potential to become a promising therapeutic agent for the treatment of various B7-H3 positive cancers. The first-in-human clinical trial for patients with advanced B7-H3 positive cancers is due to start.

Glucose-driven histone lactylation promotes the immunosuppressive activity of monocyte-derived macrophages in glioblastoma

Immunosuppressive macrophages restrict anti-cancer immunity in glioblastoma (GBM). Here, we studied the contribution of microglia (MGs) and monocyte-derived macrophages (MDMs) to immunosuppression and mechanisms underlying their regulatory function. MDMs outnumbered MGs at late tumor stages and suppressed Tcell activity. Molecular and functional analysis identified a population of glycolytic MDM expressing GLUT1 with potent immunosuppressive activity. GBM-derived factors promoted high glycolysis, lactate, and interleukin-10 (IL-10) production in MDMs. Inhibition of glycolysis or lactate production in MDMs impaired IL-10 expression and Tcell suppression. Mechanistically, intracellular lactate-driven histone lactylation promoted IL-10 expression, which was required to suppress Tcell activity. GLUT1 expression on MDMs was induced downstream of tumor-derived factors that activated the PERK-ATF4 axis. PERK deletion in MDM abrogated histone lactylation, led to the accumulation of intratumoral Tcells and tumor growth delay, and, in combination with immunotherapy, blocked GBM progression. Thus, PERK-driven glucose metabolism promotes MDM immunosuppressive activity via histone lactylation.

BTN1A1 is a novel immune checkpoint mutually exclusive to PD-L1

BackgroundWhile Programmed cell death protein 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) blockade is a potent antitumor treatment strategy, it is effective in only limited subsets of patients with cancer, emphasizing...

Spatial transcriptomic analysis of tumour-immune cell interactions in melanoma arising from congenital melanocytic nevus.

Studies on the interaction between tumour-infiltrating immune cells (TIICs) and tumour cells in melanoma arising from congenital melanocytic nevus (CMN) are lacking. The aim of this study was to determine the intratumoral immune landscape of TIICs and tumour cells during invasion and metastasis. Tissue specimens were obtained from patients with melanoma originating from CMN. Differential gene expression in melanoma cells and TIICs during invasion and metastasis was determined using spatial transcriptomics. As invasion depth increased, the expression of LGALS3, known to induce tumour-driven immunosuppression, increased in melanoma cells. In T cells, the expression of genes that inhibit T-cell activation increased with increasing invasion depth. In macrophages, the expression of genes related to the anti-inflammatory M2 phenotype was upregulated with increasing invasion depth. Compared to primary tumour cells, melanoma cells in metastatic lesions showed upregulated expression of genes associated with cancer immune evasion, including AXL and EPHA2, which impede T-cell recruitment, and BST2, associated with M2 polarization. Furthermore, T cells showed increased expression of genes related to immunosuppression, and macrophages exhibited increased expression of genes associated with the M2 phenotype. The interaction between melanomas arising from CMN and TIICs may be important for tumour progression and metastasis.

STING antagonist-loaded renal tubule epithelial cell-mimicking nanoparticles ameliorate acute kidney injury by orchestrating innate and adaptive immunity

Inflammatory responses profoundly contribute to the development of renal damage in acute kidney injury (AKI), a frequent clinical syndrome with high morbidity and mortality. However, the effects of existing strategies aiming to suppress the inflammation in AKI remain unsatisfactory due to the inability to simultaneously regulate innate and adaptive immune responses. Here, STING antagonist-loaded renal tubule epithelial cell membrane-coated nanoparticles (SNP@TEC) are developed to ameliorate AKI by orchestrating innate and adaptive immunity. As the reservation of cell membrane αV integrin, biomimetic SNP@TEC are able to target renal tubules via homotypic tropism. The carried antagonist can suppress innate immune responses through relieving STING-triggered inflammatory reaction and repolarizing macrophages to the anti-inflammatory M2 phenotype. Owing to the presence of cell membrane PD-L1, SNP@TEC can also elicit an anti-inflammatory adaptive immune response by blocking the CD80 on dendritic cells to inhibit T-cell activation. In two murine models of AKI induced by cisplatin or ischemia/reperfusion, systemic injection with SNP@TEC significantly alleviates renal damage and restores renal function. In a prophylactic model, SNP@TEC effectively prevent the transition of AKI to chronic kidney disease. SNP@TEC propose a unique approach to orchestrate innate and adaptive immunity, opening a window to remit inflammation for treating renal injury.

Repositioning baloxavir marboxil as VISTA agonist that ameliorates experimental asthma

V-type immunoglobulin domain–containing suppressor of T-cell activation (VISTA), a novel negative checkpoint regulator, plays an essential role in allergic pulmonary inflammation in mice. Treatment with a VISTA agonistic antibody could significantly improve asthma symptoms. Thus, for allergic asthma treatment, VISTA targeting may be a compelling approach. In this study, we examined the functional mechanism of VISTA in allergic pulmonary inflammation and screened the FDA-approved drugs for VISTA agonists. By using mass cytometry (CyTOF), we found that VISTA deficiency primarily increased lung macrophage infiltration in the OVA-induced asthma model, accompanied by an increased proportion of M1 macrophages (CD11b+F4/80+CD86+) and a decreased proportion of M2 macrophages (CD11b+F4/80+CD206+). Further in vitro studies showed that VISTA deficiency promoted M1 polarization and inhibited M2 polarization of bone marrow–derived macrophages (BMDMs). Importantly, we discovered baloxavir marboxil (BXM) as a VISTA agonist by virtual screening of FDA-approved drugs. The surface plasmon resonance (SPR) assays revealed that BXM (KD = 1.07 µM) as well as its active form, baloxavir acid (BXA) (KD = 0.21 µM), could directly bind to VISTA with high affinity. Notably, treatment with BXM significantly ameliorated asthma symptoms, including less lung inflammation, mucus secretion, and the generation of Th2 cytokines (IL-5, IL-13, and IL-4), which were dramatically attenuated by anti-VISTA monoclonal antibody treatment. BXM administration also reduced the pulmonary infiltration of M1 macrophages and raised M2 macrophages. Collectively, our study indicates that VISTA regulates pulmonary inflammation in allergic asthma by regulating macrophage polarization and baloxavir marboxil, and an old drug might be a new treatment for allergic asthma through targeting VISTA.

Mitochondrial-targeted curcumin inhibits T-cell activation via Nrf2 and inhibits graft-versus-host-disease in a mouse model.

Anti-inflammatory and immune suppressive agents are required to moderate hyper-activation of lymphocytes under disease conditions or organ transplantation. However, selective disruption of mitochondrial redox has not been evaluated as a therapeutic strategy for suppression of T-cell-mediated pathologies. Using mitochondrial targeted curcumin (MitoC), we studied the effect of mitochondrial redox modulation on T-cell responses by flow cytometry, transmission electron microscopy, transcriptomics, and proteomics, and the role of Nrf2 was studied using Nrf2- /- mice. MitoC decreased mitochondrial TrxR activity, enhanced mitochondrial ROS (mROS) production, depleted mitochondrial glutathione, and suppressed activation-induced increase in mitochondrial biomass. This led to suppression of T-cell responses and metabolic reprogramming towards Treg differentiation. MitoC induced nuclear translocation and DNA binding of Nrf2, leading to upregulation of Nrf2-dependent genes and proteins. MitoC-mediated changes in mitochondrial redox and modulation of T-cell responses are abolished in Nrf2- /- mice. Restoration of mitochondrial thiols abrogated inhibition of T-cell responses. MitoC suppressed alloantigen-induced lymphoblast formation, inflammatory cytokines, morbidity, and mortality in acute graft-versus-host disease mice. Disruption of mitochondrial thiols but not mROS increase inculcates an Nrf2-dependent immune-suppressive disposition in T cells for the propitious treatment of graft-versus-host disease.

P164 MRT-6160, a VAV1-directed molecular glue degrader, inhibits disease progression and inflammation in a T-cell transfer model of Colitis

Abstract Background VAV1 is an immune-restricted guanine nucleotide exchange factor critical for T-cell receptor (TCR) and B-cell receptor (BCR) signalling. The role of VAV1 in T-cells has been demonstrated in knockout mice, which exhibit decreased effector functions and resistance to autoimmune disease models, and in CRISPR-based screens, where VAV1 has been highlighted as a top hit among positive regulators of T-cell function. Until now, VAV1 has remained undruggable by conventional small molecules. MRT-6160 is a first-in-class molecular glue degrader that specifically targets VAV1 for proteasomal degradation. Given the role of VAV1 in TCR and BCR signalling, MRT-6160-mediated degradation could be an effective therapeutic approach to treating autoimmune disease. Methods We first tested the impact of MRT-6160-mediated human (h)VAV1 degradation on primary human cells using in vitro stimulation-based assays. Oral bioavailability of MRT-6160 and in vivo degradation of murine (m)VAV1 was then examined in mice. We tested the efficacy of MRT-6160 using a T-cell adoptive transfer model of colitis treating recipients of pathogenic CD45RBhigh CD4+ T-cells (8 per group) with anti-TNF (25 mg/kg, Q3D) or MRT-6160 (1 mg/kg, QD) for 41 days following cell transfer. Disease activity index (DAI), comprising stool consistency and weight loss, was assessed every 3 days. At study termination, mesenteric lymph nodes (mLN) were profiled by flow cytometry and colon tissues were assessed for cytokine expression and histopathology. Results Degradation of hVAV1 by MRT-6160 inhibited T-cell activation, proliferation, and cytokine production in a dose-dependent manner. Orally administered MRT-6160 degraded mVAV1 and inhibited colitis disease progression by 85%, reducing average end point DAI scores more than a standard of care control (vehicle, p<0.0001; anti-TNF, p=0.0107). Compared to vehicle treated groups, MRT-6160 treated mice had fewer IL-17A+ (12.6 and 5.3% respectively) and TNF+ (37.6 and 17% respectively) CD4+ T cells in mLN tissue. Colon weight:length ratio was significantly reduced in MRT-6160-treated mice (42.5 mg/cm) compared to vehicle (70.3 mg/cm) and anti-TNF (61.2 mg/cm). Finally, pro-inflammatory cytokine expression in the colon mucosa was reduced in MRT-6160-treated mice compared to vehicle (IL-6: 1305.8 and 682.3 fg/mg; TNF: 175.5 and 66.9 ng/mg; respectively), as well as histopathological evidence of disease. Conclusion MRT-6160 demonstrates strong activity in a preclinical model of colitis reducing DAI, effector cytokine production, and colon tissue damage. These data suggest that MRT-6160-mediated degradation of VAV1 may have therapeutic benefit in IBD patients and warrants further clinical development.

Post-translational Modification of PD-1: Potential Targets for Cancer Immunotherapy.

Activation of effector T cells leads to upregulation of PD-1, which can inhibit T-cell activity following engagement with its ligand PD-L1. Post-translational modifications (PTM), including glycosylation, phosphorylation, ubiquitination, and palmitoylation, play a significant role in regulating PD-1 protein stability, localization, and interprotein interactions. Targeting PTM of PD-1 in T cells has emerged as a potential strategy to overcome PD-1-mediated immunosuppression in cancer and enhances antitumor immunity. The regulatory signaling pathways that induce PTM of PD-1 can be suppressed with small-molecule inhibitors, and mAbs can directly target PD-1 PTMs. Preliminary outcomes from exploratory studies suggest that focusing on the PTM of PD-1 has strong therapeutic potential and can enhance the response to anti-PD-1.

Alteration of functionality and differentiation directed by changing gene expression patterns in myeloid-derived suppressor cells (MDSCs) in tumor microenvironment and bone marrow through early to terminal phase of tumor progression.

Myeloid-derived suppressor cells are heterogenous immature myeloid lineage cells that can differentiate into neutrophils, monocytes, and dendritic cells as well. These cells have been characterized to have potent immunosuppressive capacity in neoplasia and a neoplastic chronic inflammatory microenvironment. Increased accumulation of myeloid-derived suppressor cells was reported with poor clinical outcomes in patients. They support neoplastic progression by abrogating antitumor immunity through inhibition of lymphocyte functions and directly by facilitating tumor development. Yet the shifting genetic signatures of this myeloid lineage cell toward immunosuppressive functionality in progressive tumor development remain elusive. We have attempted to identify the gene expression profile using lineage-specific markers of these unique myeloid lineage cells in a tumor microenvironment and bone marrow using a liquid transplantable mice tumor model to trace the changing influence of the tumor microenvironment on myeloid-derived suppressor cells. We analyzed the phenotype, functional shift, suppressive activity, differentiation status, and microarray-based gene expression profile of CD11b+Gr1+ lineage-specific cells isolated from the tumor microenvironment and bone marrow of 4 stages of tumor-bearing mice and compared them with control counterparts. Our analysis of differentially expressed genes of myeloid-derived suppressor cells isolated from bone marrow and the tumor microenvironment reveals unique gene expression patterns in the bone marrow and tumor microenvironment-derived myeloid-derived suppressor cells. It also suggests T-cell suppressive activity of myeloid-derived suppressor cells progressively increases toward the mid-to-late phase of the tumor and a significant differentiation bias of tumor site myeloid-derived suppressor cells toward macrophages, even in the presence of differentiating agents, indicating potential molecular characteristics of myeloid-derived suppressor cells in different stages of the tumor that can emerge as an intervention target.

Tissue biomarkers of immune checkpoint inhibitor therapy.

Cancer immunotherapy has been rejuvenated by the growing understanding of the immune system's role in tumor activity over the past two decades. During cancer initiation and progression, tumor cells employ various mechanisms that resemble peripheral immune tolerance to evade the antitumor responses of the immune system. Immune checkpoint molecules are the major mechanism of immune resistance that are exploited by tumor cells to inhibit T-cell activation and suppress immune responses. The targeting of immune checkpoint pathways has led to substantial improvements in survival rates in a number of solid cancers. However, a lack of understanding of the heterogeneity of the tumor microenvironment (TME) has resulted in inefficient therapy responses. A greater understanding of the TME is needed to identify patients likely to respond, and those that will have resistance to immune checkpoint inhibitors (ICIs). Advancement in spatial single-cell technologies has allowed deeper insight into the phenotypic and functional diversities of cells in the TME. In this review, we provide an overview of ICI biomarkers and highlight how high-dimensional spatially resolved, single-cell approaches provide deep molecular insights into the TME and allow for the discovery of biomarkers of clinical benefit.