Upregulation Of MHC Research Articles

Exploration of immunomodulatory mechanism of caprine Wharton’s jelly derived mesenchymal stem cells

The present study was aimed to explore the possible mechanisms by which caprine Wharton’s jelly-derived MSCs (WJ-MSCs) perform their immunomodulatory function. WJ-MSCs were isolated through explants culture and characterized as per ISCT criteria using culture behavior, expression of surface markers by PCR, FACS and immunocytochemical localization (ICC), trilineage differentiation potential etc. Secretory behavior for important biomolecules (IDO, TGFβ1, VEGF, IL6) was evaluated by ICC and western blot assay. Cell-to-cell communication was studied by culturing cells in cell–cell contact and trans-well system. The MSCs when co-cultured with activated Tc and Th cells, down-regulation of T cell cytokine as well as upregulation of immunomodulatory factors (VEGF A, IL10, IL6, IDO, iNOS, PTGS2, HGF, TGFβ, CXCL10, CXCL11) was noticed in both cell–cell contact and trans-well culture system which was significantly higher in cell–cell contact system. Trilineage differentiation of MSCs showed significant upregulation of MHC I (CAHI) and MHC II (CLA DRB3) molecules suggesting better clinical applications of MSCs without differentiation to avoid immune rejection. It can be concluded that WJ-MSCs perform their immunomodulation through the secretion of a battery of biomolecules and work in both cell–cell contact manner and through their secretome.

Low-dose SAHA enhances CD8+ T cell-mediated antitumor immunity by boosting MHC I expression in non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) is a highly aggressive type of lung cancer with poor responses to traditional therapies such as surgery, radiotherapy, and chemotherapy. While immunotherapy has become an effective approach for treating multiple types of cancer, solid tumors frequently exhibit immune escape through various mechanisms, including downregulation of MHC I expression. However, whether the upregulation of MHC I expression can improve the immunotherapeutic effect on NSCLC remains unexplored. Suberoylanilide hydroxamic acid (SAHA) is a potent histone deacetylase (HDAC) inhibitor that has been applied clinically to treat lymphoma, but a high dose of SAHA kills tumor cells and normal cells without preference. Here, we report that low-dose SAHA enhances CD8+ T cell-mediated antitumor immunity by upregulating MHC I expression in NSCLC cells. Flow cytometric analysis, quantitative real-time PCR and western blot were used to analyze the expression of MHC I, STAT1 and Smad2/3 in both human and mouse NSCLC cell lines after SAHA treatment. The nuclear translocation of phosphorylated STAT1 and Smad2/3 was investigated by western blot and immunofluorescence staining. The mechanisms underlying STAT1 and Smad2/3 upregulation were analyzed through database searches and chromatin immunoprecipitation-qPCR. Finally, we assessed the antitumor effect of specific CD8+ T cells with SAHA treatment in vivo and in vitro. We showed that low-dose SAHA upregulated the expression of MHC I in NSCLC cell lines without affecting cell viability. We also provided evidence that high levels of MHC I induced by SAHA promoted the activation, proliferation, and cytotoxicity of specific CD8+ T cells in mouse models. Mechanistically, low-dose SAHA increased the levels of H3K9ac and H3K27ac in the promoters of the STAT1, Smad2 and Smad3 genes in NSCLC cells by inhibiting HDAC activity, resulting in elevated expression levels of STAT1, Smad2 and Smad3. The nuclear translocation of phosphorylated STAT1 and Smad2/3 markedly upregulated the expression of MHC I in NSCLC cells. Low-dose SAHA enhances CD8+ T cell-mediated antitumor immunity by boosting MHC I expression in NSCLC cells. Thus, we revealed a key mechanism of SAHA-mediated enhanced antitumor immunity, providing insights into a novel immunotherapy strategy for NSCLC.

Establishment of an in vitro evaluation method for immunomodulatory functions of yeast strains.

Saccharomyces cerevisiae, a widely studied yeast known for its industrial applications, is increasingly recognized for its potential in immunomodulation. This study aimed to systematically analyze and compare the immune-modulating properties of various S. cerevisiae strains under controlled experimental conditions. Three essential signals crucial for immune response activation were evaluated to elucidate the immunological responses elicited by these strains, i.e., dendritic cells (DC) cytokine secretion profiles, maturation status, and T cell polarization. Analysis of DC cytokine secretion profiles and maturation status revealed that all tested yeast strains induced DC activation, characterized by significant IL-6 secretion and modest IL-10 induction, as well as upregulation of MHC II molecules. Additionally, strain-specific effects were observed, particularly, strain AJM109 and Y1383 uniquely enhanced CD86 and PD-L1 expression, respectively, suggesting differential impacts on DC co-stimulatory signaling. Furthermore, strain Y1383 showed a unique capacity to support Treg-mediated immune suppression, demonstrating its potential in immune tolerance induction. These findings underscore the complexity of S. cerevisiae-based immune modulation and emphasize the importance of standardized evaluation methods to distinguish their specific immunological effects.

Notch signaling suppresses neuroendocrine differentiation and alters the immune microenvironment in advanced prostate cancer.

Notch signaling can have either an oncogenic or tumor suppressive function in cancer depending on the cancer type and cellular context. While Notch can be oncogenic in early prostate cancer, we identified significant downregulation of the Notch pathway during prostate cancer progression from adenocarcinoma to neuroendocrine prostate cancer where it functions as a tumor suppressor. Activation of Notch in neuroendocrine and Rb1/Trp53-deficient prostate cancer models led to phenotypic conversion towards a more indolent non-neuroendocrine state with glandular features and expression of luminal lineage markers. This was accompanied by up-regulation of MHC and type I interferon and immune cell infiltration. Overall, these data support Notch signaling as a suppressor of neuroendocrine differentiation in advanced prostate cancer and provides insights into how Notch signaling influences lineage plasticity and the tumor microenvironment.

Efficacy of LCMV-based cancer immunotherapies is unleashed by intratumoral injections of polyI:C

BackgroundLymphocytic choriomeningitis virus (LCMV) belongs to the Arenavirus family known for inducing strong cytotoxic T-cell responses in both mice and humans. LCMV has been engineered for the development of cancer...

Upregulation of MHC I antigen processing machinery gene expression in breast cancer cells by Trichostatin A

Epigenetic alterations associated with cancer have been shown to facilitate tumorigenesis and promote metastasis. In the study of cancer metastasis, epigenetics has been revealed to play a crucial role in supporting tumour immune evasion. As a result, epigenetic drugs have been identified as potential agents to activate anti-tumour immune responses and reverse tumour immunologically tolerant states. Mounting evidence is showing aberrant expression of MHC class I antigen processing molecules in cancers and their upregulation as a potential indicator for anti-tumour immunity. In this study, we demonstrate that the epigenetic drug Trichostatin A (TSA), a histone deacetylase inhibitor, can restore MHC I antigen presentation machinery (MHC I APM) genes in human breast cancer cells (MCF-7). Treatment with TSA resulted in the upregulation of MHC I, B2M, and PSMB9 in MCF-7 monolayer cells, and MHC I, B2M, PSMB9, PSMB8, TAP1, and TAP2 in MCF-7 spheroid cells. Interestingly, treatment with TSA also increased CD274 expression in these cells and enhanced the invasion ability of the MCF-7 spheroid. This aggressive behaviour was confirmed by increased expression of metastatic-related genes, SCN5A (nNav1.5 protein) and MMP1. In summary, although the restoration of MHC I APM expression was achieved by TSA, the upregulation of metastatic genes and CD274 also enhanced the invasion ability of breast cancer cells. These findings suggest the need for careful consideration when utilizing epigenetic drugs for breast cancer therapy.

Upregulation of MHC I Antigen Processing Machinery Gene Expression in Breast Cancer Cells by Trichostatin A

Upregulation of MHC I Antigen Processing Machinery Gene Expression in Breast Cancer Cells by Trichostatin A

Single-Cell RNA-Seq Analysis Reveals Distinct Tumor and Immunosuppressive T Cell Phenotypes in CLL Patients Treated with Ibrutinib

Introduction: The development of Bruton tyrosine kinase inhibitors (BTKIs) and their introduction into clinical practice represents a major advance in the treatment of chronic lymphocytic leukemia (CLL). Monotherapy with ibrutinib or other BTKIs generally do not induce complete remissions or undetectable minimal residual disease (uMRD) even with extended therapy. The reason why some patients relapse, and some have minimal residual disease is unknown. Therefore, there is a need to understand the differences between ibrutinib sensitive and resistant CLL cells along with the immune microenvironment to identify novel therapeutic targets. Methods: Here, we investigate the cellular heterogeneity of peripheral blood mononuclear cells from patients with CLL treated with ibrutinib using single-cell RNA sequencing. To understand ibrutinib resistance mechanisms, samples were collected from 8 patients at baseline (before treatment) (1), where BTK C481S is present with low variant allele frequency (VAF) (2) and at time of relapse (3). Data from these were compared to ibrutinib sensitive patient samples at baseline (1) (before treatment), 3yr (2) and 5yr (3) on treatment timepoints. Single cells were isolated using the 10X Genomics 5' immune profiling kit. Data were processed with CellRanger v3.1.0. Poor quality cells were filtered out based on a high proportion of mitochondrial reads and low overall feature count. Sample variation was reduced using Batchelor to aid clustering. Clustering was performed using the partitioning and Leiden methods. Cluster top markers were calculated using functions from monocle3. Identity mapping was performed using Seurat and a published PBMC reference dataset. Results: Single-cell RNA sequencing revealed transcriptional heterogeneity within the B cell cluster (Fig 1A). Three subpopulations of B cells were defined based on differential representation in the ibrutinib-sensitive and resistant patients. Ibrutinib sensitive cells showed enrichment of B cell populations with upregulation of MHC I molecules and TNF family members. We also identified that inflammatory response and metabolic-related pathways were decreased, whereas cellular response to stress and DNA repair programs were increased in the ibrutinib resistance samples. Gene module analysis showed that ibrutinib sensitive samples had an increase in T cell activation, RNA splicing, cell adhesion and migration programs during therapy. We hypothesized that the emergence of BTK C481S mutation in ibrutinib-resistant cells would lead to a distinct transcriptional profile. Long-read sequencing was performed using Oxford Nanopore technology. BTK-mutant cells were identified based on the presence of two or more unique RNA molecules detected with the C481S mutation and these were predominantly identified in the low-VAF and relapse samples. However, there was no significant difference between BTK-mutant cells and the remaining B cells. To see if T cell phenotypes reflected the differences observed in B cell transcriptional state, we characterized and quantified T cell populations according to ibrutinib response and investigated the changes in the T cell population. Ibrutinib markedly increased CD4+ and CD8+ T cell numbers in both resistant and sensitive CLL patients. However, there was a significant (p<0.05) enrichment of Tregs in the ibrutinib-resistant samples. We found a connection between the immunosuppressive phenotype in the microenvironment demonstrating tumor's intrinsic immunological reactive program with exhausted T cells. Also, we found significant difference in the expression of checkpoint molecules and suppressive genes in T cells (Fig 1B) and NK cells. Conclusion: Our findings demonstrate that the B cell population in ibrutinib-resistant and ibrutinib sensitive CLL patients exhibit distinct transcriptional states. At the single-cell level, our findings demonstrate a systematic picture of diverse malignancy and microenvironmental changes in CLL. Overall, these findings provide an insight into the complex molecular and cellular interactions of CLL that may have a crucial role in BTKI resistance.

Side-Chain Immune Oxysterols Induce Neuroinflammation by Activating Microglia.

In individuals with Alzheimer's disease, the brain exhibits elevated levels of IL-1β and oxygenated cholesterol molecules (oxysterols). This study aimed to investigate the effects of side-chain oxysterols on IL-1β expression using HMC3 microglial cells and ApoE-deficient mice. Treatment of HMC3 cells with 25-hydroxycholesterol (25OHChol) and 27-hydroxycholesterol (27OHChol) led to increased IL-1β expression at the transcript and protein levels. Additionally, these oxysterols upregulated the surface expression of MHC II, a marker of activated microglia. Immunohistochemistry performed on the mice showed increased microglial expression of IL-1β and MHC II when fed a high-cholesterol diet. However, cholesterol and 24s-hydroxycholesterol did not increase IL-1β transcript levels or MHC II expression. The extent of IL-1β increase induced by 25OHChol and 27OHChol was comparable to that caused by oligomeric β-amyloid, and the IL-1β expression induced by the oxysterols was not impaired by polymyxin B, which inhibited lipopolysaccharide-induced IL-1β expression. Both oxysterols enhanced the phosphorylation of Akt, ERK, and Src, and inhibition of these kinase pathways with pharmacological inhibitors suppressed the expression of IL-1β and MHC II. The pharmacological agents chlorpromazine and cyclosporin A also impaired the oxysterol-induced expression of IL-1β and upregulation of MHC II. Overall, these findings suggest that dysregulated cholesterol metabolism leading to elevated levels of side-chain oxysterols, such as 25OHChol and 27OHChol, can activate microglia to secrete IL-1β through a mechanism amenable to pharmacologic intervention. The activation of microglia and subsequent neuroinflammation elicited by the immune oxysterols can contribute to the development of neurodegenerative diseases.

Goat milk extracellular vesicles: immuno-modulation effects on porcine monocyte-derived macrophages in vitro.

Extracellular vesicles (EVs) are nanometric-membrane-bound sub-cellular structures, which can be recovered from milk. Milk EVs have drawn increasing interest due to their potential biomedical applications, therefore it is important to investigate their impact on key immune cells, such as macrophages. In this work, the immunomodulatory effects of goat milk EVs on untreated (moMФ) and classically activated (moM1) porcine monocyte-derived macrophages were investigated using flow cytometry, ELISA, and gene expression assays. These particles were efficiently internalized by macrophages and high doses (60 mg protein weight) triggered the upregulation of MHC I and MHC II DR on moMФ, but not on moM1. In moMФ, exposure to low doses (0.6 mg) of mEVs enhanced the gene expression of IL10, EBI3, and IFNB, whereas high doses up-regulated several pro-inflammatory cytokines. These nanosized structures slightly modulated cytokine gene expression on moM1. Accordingly, the cytokine (protein) contents in culture supernatants of moMФ were mildly affected by exposure to low doses of mEVs, whereas high doses promoted the increased release of TNF, IL-8, IL-1a, IL-1b, IL-1Ra, IL-6, IL-10, and IL-12. The cytokines content in moM1 supernatants was not critically affected. Overall, our data support a clinical application of these molecules: they polarized macrophages toward an M1-like phenotype, but this activation seemed to be controlled, to prevent potentially pathological over-reaction to stressors.

The initial report of phase I trial of VG2025, a non-attenuated HSV-1 oncolytic virus expressing IL-12 and IL-15/RA payloads, in patients with advanced solid tumors.

2580 Background: VG2025 is a non-attenuated HSV-1 Oncolytic virus (OV). The wildtype neurovirulence is controlled by the Transcription and Translation Dual Regulation (TTDR) of ICP27 and ICP34.5 proteins. IL-12, IL-15, IL-15Ra payloads are controlled by tumor promoter CxCR4. The native promoter of ICP27 was replaced with a promoter for Carcinoembryonic Antigen (CEA). Here we report a first-in-human, open label, study to evaluate the safety, pharmacokinetics (PK), and biologic effects of VG2025 in patients (pts) with advanced solid tumors progressed after standard of care from China and United States. The study is actively recruiting. NCT05266612. Methods: Dose escalation follows a 3+3 design at 4 dose levels as intratumoral, and image guided injections into deep lesions on days 1 and 15 of each 28 days treatment cycle. PK and viral shedding (DNA), samples from biopsies, blood, urine, and swabs from injection site and other anatomical locations were analyzed by PCR. Changes of cytokines and lymphocyte subsets in blood were also observed as pharmacodynamic parameters. Results: As of 10 Jan 2023, 10 pts received doses of 1.0x10^8 and 2.0x10^8 PFU. 5 males and 5 females with the median age of 58 years were enrolled. 20% were PD(L)1 refractory, 20% had 2 Prior lines of therapy and 60% ≥3. The Median CEA level was 7.4. Tumor types were: 2 Duodenal Adeno Ca., 1 Pancreatic, 1 Ovarian, 1 Leiomyosarcoma, 1 Salivary Duct Ca., 1 Hepatocellular Ca (HCC), 1 Intrahepatic Cholangiocarcinoma (ICC), 1 Colorectal Ca (CRC) and 1 Colon Ca. No Dose Limiting Toxicities were observed. Any grade treatment-related AEs (TRAEs) was 70%, the most common TRAEs was fever 60%. Grade ≥3 TRAEs were 50% [3 pts had grade 4 Lymphocyte decreased (all recovered)], 1 had grade 3 COVID-19 and 1 had grade 3 nausea and vomiting. 4 pt had SAEs (2 cases of COVID-19, 1 Ascites and 1 Nausea and Vomiting). No TRAEs leading to dose reduction and treatment discontinuation. No pts had positive viral shedding. 4 pts were efficacy evaluable; ORR 25% (1 pt with ICC had confirmed PR with -45%) and DCR 100% based on RECIST v1.1. The PR pt had meaningful reductions in CEA levels. Tumor shrinkage was also observed in non-injected lesions demonstrating an abscopal effect. Nanostring analysis of paired biopsies from the PR pt demonstrate upregulation of genes for integrin signaling pathway, activation of CD8+ T cells and T cell-based immunity, upregulation of antigen-presenting MHC (HLA-DQA1 and HLA-DRB1) and chemokine receptor (CMKLR1) genes. Cellular immunity was activated by upregulation of Th1 cells, macrophage-associated genes and downregulation of Treg-associated genes. The results are consistent with the mechanism of action of VG2025. Analysis is ongoing with other subjects. Conclusions: Monotherapy activity was observed with an acceptable safety profile in heavily pretreated pts with advanced solid tumors. Clinical trial information: NCT05266612 .

Nucleated red blood cells: unexpected orchestrators of fetal immunity

Abstract Red blood cells (RBCs) are not typically considered active immune mediators. This dogma stems from the fact that RBC precursors discard organelles as they mature, thus losing the ability to alter gene expression in response to stimuli. Intriguingly, nucleated RBCs (nRBCs) circulate in human fetuses and neonates. Due to evolutionary pressure for successful reproduction, circulation of nRBCs during pregnancy is likely important. However, the role of nRBCs in uteroremains unknown. To define the role of human nRBCs, we queried single cell RNA-seq data and found that transcriptomics support nRBCs as putative immune mediators. Unexpectedly, we found that nRBCs express antigen processing & presentation machinery. nRBCs constitutively express MHC II & co-stimulatory molecules, hallmarks of specialized antigen-presenting cells. We further demonstrated that nRBCs internalize and cleave antigens. Currently, we aim to determine if nRBCs present antigens to T cells and to characterize the elicited response. In addition, we found that nRBCs express pattern recognition receptors capable of detecting pathogens and initiating an antimicrobial response. We demonstrated that nRBCs respond to viral infection through upregulation of antiviral genes, interferons/interferon-stimulated genes, MHC I, and pro-inflammatory cytokines/chemokines. These data suggest a putative functionality for nRBCs in mediating antiviral immunity in utero. We are currently investigating antiviral functions of nRBCs. Together, our findings shed light on an unexpected orchestrator of fetal immunity. Knowledge of the fetal immune system has potential to help us understand health and disease during pregnancy, as a neonate, and likely every stage of life after. Supported by grants from NIH/NIDDK 5T32DK007780, NIH/NIGMS K12GM081259, Burroughs Wellcome Fund 2022 Next Gen Pregnancy Initiative Award

Single‐cell transcriptomics reveals a senescence‐associated IL‐6/CCR6 axis driving radiodermatitis

Irradiation‐induced alopecia and dermatitis (IRIAD) are two of the most visually recognized complications of radiotherapy, of which the molecular and cellular basis remains largely unclear. By combining scRNA‐seq analysis of whole skin‐derived irradiated cells with genetic ablation and molecular inhibition studies, we show that senescence‐associated IL‐6 and IL‐1 signaling, together with IL‐17 upregulation and CCR6+‐mediated immune cell migration, are crucial drivers of IRIAD. Bioinformatics analysis colocalized irradiation‐induced IL‐6 signaling with senescence pathway upregulation largely within epidermal hair follicles, basal keratinocytes, and dermal fibroblasts. Loss of cytokine signaling by genetic ablation in IL‐6−/− or IL‐1R−/− mice, or by molecular blockade, strongly ameliorated IRIAD, as did deficiency of CCL20/CCR6‐mediated immune cell migration in CCR6−/− mice. Moreover, IL‐6 deficiency strongly reduced IL‐17, IL‐22, CCL20, and CCR6 upregulation, whereas CCR6 deficiency reciprocally diminished IL‐6, IL‐17, CCL3, and MHC upregulation, suggesting that proximity‐dependent cellular cross talk promotes IRIAD. Therapeutically, topical application of Janus kinase blockers or inhibition of T‐cell activation by cyclosporine effectively reduced IRIAD, suggesting the potential of targeted approaches for the treatment of dermal side effects in radiotherapy patients.

Sulfavant A as the first synthetic TREM2 ligand discloses a homeostatic response of dendritic cells after receptor engagement

ObjectiveThe immune response arises from a fine balance of mechanisms that provide for surveillance, tolerance, and elimination of dangers. Sulfavant A (SULF A) is a sulfolipid with a promising adjuvant activity. Here we studied the mechanism of action of SULF A and addressed the identification of its molecular target in human dendritic cells (hDCs).MethodsAdjuvant effect and immunological response to SULF A were assessed on DCs derived from human donors. In addition to testing various reporter cells, target identification and downstream signalling was supported by a reverse pharmacology approach based on antibody blocking and gene silencing, crosstalk with TLR pathways, use of human allogeneic mixed lymphocyte reaction.ResultsSULF A binds to the Triggering Receptor Expressed on Myeloid cells-2 (TREM2) and initiates an unconventional maturation of hDCs leading to enhanced migration activity and up-regulation of MHC and co-stimulatory molecules without release of conventional cytokines. This response involves the SYK-NFAT axis and is compromised by blockade or gene silencing of TREM2. Activation by SULF A preserved the DC functions to excite the allogeneic T cell response, and increased interleukin-10 release after lipopolysaccharide stimulation.ConclusionSULF A is the first synthetic small molecule that binds to TREM2. The receptor engagement drives differentiation of an unprecedented DC phenotype (homeDCs) that contributes to immune homeostasis without compromising lymphocyte activation and immunogenic response. This mechanism fully supports the adjuvant and immunoregulatory activity of SULF A. We also propose that the biological properties of SULF A can be of interest in various physiopathological mechanisms and therapies involving TREM2.

Abstract 3874: Engineered microphysiological systems for testing effectiveness of cell-based cancer immunotherapies in small cell lung cancer

Abstract Background: Immune cell trafficking into solid tumors has proven challenging due to immune cell exclusion by vascular barriers. Additionally, testing next-generation immune therapies remains difficult in animal models and requires sophisticated ex vivo systems to study human tumor biology and predict treatment response in real time. SCLC comprises approximately 15% of all lung cancer cases and despite recent incorporation of immune checkpoint blockade (ICB) into first line treatment, patients with SCLC continue to have a poor prognosis and limited treatment options. Notably, recent transcriptomic profiling of SCLC has indicated significant inter-tumoral and intra-tumoral heterogeneity. We have previously demonstrated that neuroendocrine SCLC subpopulations downregulate MHC I, whereas non-neuroendocrine SCLC subpopulations exhibit increased innate immune signaling and robust upregulation of MHC I antigen presentation. Here we interrogate the vulnerability of SCLC populations to NK cells and investigate their trafficking using a novel microphysiological ex vivo model. Methods: We developed a 3-dimensional (3D) microphysiological TME model of vascularized SCLC, comprising tumor spheroids embedded in a microvascular network self-assembled by endothelial cells and lung fibroblasts. Real time fluorescence imaging, cell-titer Glo and flow cytometry were used to quantify tumor cell viability in 2D and 3D microfluidic co-culture cytotoxicity assays, using primary NK cells and the NK92 cell line. Results: We demonstrated robust targeting of MHC-I low SCLC cells by primary human NK cells and NK92, and found that MHC-I high SCLC subpopulations show resistance to NK cell-mediated killing. To dissect the influence of vascular barriers on immune cell trafficking, we developed a 3D microphysiological TME model of vascularized SCLC, which successfully recapitulated tumor-vascular-immune interactions in a human-relevant platform as evidenced by vascular perfusion by NK cells. Using this model, we were able to demonstrate that the activation of cGAS-STING signaling in endothelial cells results in the secretion of CXCL10 and upregulation of adhesion molecules (ICAM-1, VCAM-1, E-selectin), promoting immune cell recruitment. Conclusions: We successfully developed a 3D microphysiological model of vascularized SCLC TME and show proof of principle that this model can be used for preclinical studies of cell therapies. Using this novel microphysiological system, we revealed that co-opting STING signaling can promote NK cell recruitment to the SCLC TME. Taken together, we show that microphysiological systems can be used to identify and test therapeutic vulnerabilities while studying immune infiltration and killing in the TME, offering an accurate and adaptable platform for biologic discovery and therapeutic development. Citation Format: Marco Campisi, Minyue Chen, Nathaniel Spicer, Patrick Lizotte, Erik H. Knelson, Cloud P. Paweletz, David A. Barbie, Navin R. Mahadevan. Engineered microphysiological systems for testing effectiveness of cell-based cancer immunotherapies in small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3874.

Abstract 5590: Inhibition of the autophagy protein Vps34 induces tumor cell secretion of proinflammatory chemokines

Abstract Autophagy is the cellular process by which cytoplasmic contents are degraded and recycled through a lysosomal pathway. In cancer, autophagy can contribute to both tumor promotion and tumor suppression, and emerging evidence supports a role in resistance to immunotherapy. We investigated whether inhibition of autophagy with a small molecule inhibitor of the class III phosphoinositide 3-kinase Vps34 could stimulate anti-tumor immune responses and potentiate the efficacy of immune checkpoint blockade (ICB). Treatment with the Vps34 inhibitor (Vps34i) inhibited autophagy and was weakly cytotoxic to B16F10, MC38, EMT6 and CT26 mouse syngeneic tumor cell lines. In certain cancers, autophagy has been linked to lysosomal degradation of MHC I proteins, thereby downregulating expression and contributing to immune evasion. Notably, we observed minimal upregulation of MHC I surface expression on a subset of mouse and human cell lines. We further explored whether autophagy inhibition would result in release of any soluble immune stimulatory factors from mouse tumor cell lines. Inhibition of Vps34 markedly increased the secretion of several proinflammatory chemokines, including CCL5 and CXCL10. Increased chemokine secretion was also observed in a panel of human cancer cell lines, including NCI-H2009 lung cancer and PC-3 prostate cancer, confirming that the response is observed in human cancer cell lines derived from different tissue origins. As the chemokines CCL5 and CXCL10 are critical to the development of robust anti-tumor immunity, we next tested whether Vps34i treatment could potentiate the anti-tumor efficacy of ICB. We explored the activity of Vps34i as a single agent and in combination with anti-PD-1 antibody in three different syngeneic tumor models, including EMT6, CT26 and MC38. No single agent activity was observed in these models, however, combination of anti-PD-1 and Vps34i significantly inhibited the growth of CT26 tumors compared to control. Anti-tumor efficacy of combination treatment was not significantly different compared to single agents, and no complete tumor regressions were observed. No significant increases in CCL5 and CXCL10 were observed in the serum of combination treated mice, potentially explaining the lack of robust efficacy. Our results suggest that inhibition of autophagy promotes the secretion of proinflammatory cytokines from mouse and human cancer cells in vitro. As the autophagy pathway exhibits cross talk with other major cell signaling pathways, the tumor contexture may be a critical determinant of the role of autophagy in anti-tumor immune responses. Future experiments will explore which tumor contexts are sensitive to combination of autophagy inhibition and ICB. Citation Format: Marie Bernardo, Yu-an Zhang, Martin Graf, Jane Cheng, Fangxian Sun, Virna Cortez-Retamozo, Sukhvinder Sidhu, Eladio Marquez, Donald Jackson, Jack Pollard, Timothy R. Wagenaar, Donald Shaffer. Inhibition of the autophagy protein Vps34 induces tumor cell secretion of proinflammatory chemokines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5590.

Remodeling of the tumor microenvironment via disrupting Blimp1+ effector Treg activity augments response to anti-PD-1 blockade

BackgroundAccumulation of Foxp3+ regulatory T (Treg) cells in the tumor often represents an important mechanism for cancer immune evasion and a critical barrier to anti-tumor immunity and immunotherapy. Many tumor-infiltrating Treg cells display an activated phenotype and express the transcription factor Blimp1. However, the specific impact of these Blimp1+ Treg cells and their follicular regulatory T (TFR) cell subset on tumor and the underlying mechanisms of action are not yet well-explored.MethodsVarious transplantable tumor models were established in immunocompetent wild-type mice and mice with a Foxp3-specific ablation of Blimp1. Tumor specimens from patients with metastatic melanoma and TCGA datasets were analyzed to support the potential role of Treg and TFR cells in tumor immunity. In vitro culture assays and in vivo adoptive transfer assays were used to understand how Treg, TFR cells and antibody responses influence tumor control. RNA sequencing and NanoString analysis were performed to reveal the transcriptome of tumor-infiltrating Treg cells and tumor cells, respectively. Finally, the therapeutic effects of anti-PD-1 treatment combined with the disruption of Blimp1+ Treg activity were evaluated.ResultsBlimp1+ Treg and TFR cells were enriched in the tumors, and higher tumoral TFR signatures indicated increased risk of melanoma metastasis. Deletion of Blimp1 in Treg cells resulted in impaired suppressive activity and a reprogramming into effector T-cells, which were largely restricted to the tumor-infiltrating Treg population. This destabilization combined with increased anti-tumor effector cellular responses, follicular helper T-cell expansion, enhanced tumoral IgE deposition and activation of macrophages secondary to dysregulated TFR cells, remodeled the tumor microenvironment and delayed tumor growth. The increased tumor immunogenicity with MHC upregulation improved response to anti-PD-1 blockade. Mechanistically, Blimp1 enforced intratumoral Treg cells with a unique transcriptional program dependent on Eomesodermin (Eomes) expression; deletion of Eomes in Blimp1-deficient Treg cells restored tumor growth and attenuated anti-tumor immunity.ConclusionsThese findings revealed Blimp1 as a new critical regulator of tumor-infiltrating Treg cells and a potential target for modulating Treg activity to treat cancer. Our study has also revealed two FCERIA-containing immune signatures as promising diagnostic or prognostic markers for melanoma patients.

SERONEGATIVE AUTOIMMUNE NECROTIZING MYOPATHY: ITS COURSE ACCELERATED BY COXSACKIE B INFECTION

TOPIC: Critical Care TYPE: Medical Student/Resident Case Reports INTRODUCTION: We present a patient with necrotizing myopathy and rapid progression of muscle weakness, including respiratory muscles, leading to hypercapnic respiratory failure requiring mechanical ventilation following a myopericardial infection thought to be secondary to coxsackie B virus (CVB). This suggests that CVB accelerated the progression of the antibody-negative Immune mediated necrotizing myopathy (IMNM). CASE PRESENTATION: A 43 year old woman was hospitalized with proximal muscle weakness for 4 months with 2 weeks of substernal chest pain, which worsens when lying down and relieved when leaning forward. Progressive dyspnea on exertion and led to hypercapnic respiratory failure requiring mechanical ventilation. Laboratory and imaging findings were significant for creatinine kinase of 4,796, a troponin of 6.22, elevated antibody titers for CVB 1-6, and a pericardial effusion on echocardiogram. Pertinent negatives include acetylcholine receptor antibody (ab), antinuclear ab, skeletal muscle ab, Anti-signal recognition particle (SRP) and anti-hydroxy-3-methylglutarylCoA reductase (HMGCR) auto-ab. Due to a suspicion for inflammatory myopathy on MRI, a biopsy of quadriceps muscle showed predominant necrosis with minimal inflammation (monocytes, lymphocytes), myophagocytosis, and patchy MHC upregulation. Electromyogram (EMG) was negative for neuropathy or myasthenia gravis [4]. The constellation of findings was consistent with autoimmune necrotizing myopathy, its course complicated by myopericarditis thought to be secondary to CVB. The patient received IVIG, rituximab and high dose steroids, and was discharged to a long term acute care facility, where the patient's strength gradually improved. She was eventually weaned off of ventilator support. DISCUSSION: Necrotizing myopathy is a relatively recently defined form of autoimmune myopathy characterized by less inflammation and more necrosis in muscle tissue than seen in polymyositis [1]. Autoimmune myopathies are rare, with a prevalence of 9–14 cases per 100,000 people [5, 6]. Seronegative IMNM has not been characterized as well as seropositive IMNM [4]. While European Neuromuscular Centre criteria do not require muscle biopsy to diagnose seropositive IMNM, a muscle biopsy is essential/required for diagnosis of seronegative IMNM [3, 4]. CONCLUSIONS: In the setting of myocarditis likely secondary to CVB, the patient's myopathy rapidly worsened to include respiratory muscles and led to mechanical ventilation. This course of events strongly raises the possibility that coxsackie B infection led to acceleration of myopathy. REFERENCE #1: Adler BL, Christopher-Stine L. Triggers of inflammatory myopathy: insights into pathogenesis. Discov Med 2018;25:75–83. REFERENCE #2: Dalakas MC. Myositis: are autoantibodies pathogenic in necrotizing myopathy? Nat Rev Rheumatol 2018;14:251–2. REFERENCE #3: Khan NAJ, Khalid S, Ullah S, et al. Necrotizing autoimmune myopathy: a rare variant of idiopathic inflammatory myopathies. J Investig Med High Impact Case Rep 2017;5:232470961770903. DISCLOSURES: No relevant relationships by Erik Anderson, source=Web Response No relevant relationships by Amanda Eng, source=Web Response No relevant relationships by Padmanabhan Krishnan, source=Web Response

Modulation of the mTOR pathway plays a central role in dendritic cell functions after Echinococcus granulosus antigen recognition

Immune evasion is a hallmark of persistent echinococcal infection, comprising modulation of innate immune cells and antigen-specific T cell responses. However, recognition of Echinococcus granulosus by dendritic cells (DCs) is a key determinant of the host's response to this parasite. Given that mTOR signaling pathway has been described as a regulator linking metabolism and immune function in DCs, we reported for the first time in these cells, global translation levels, antigen uptake, phenotype, cytokine transcriptional levels, and splenocyte priming activity upon recognition of the hydatid fluid (HF) and the highly glycosylated laminar layer (LL). We found that LL induced a slight up-regulation of CD86 and MHC II in DCs and also stimulated the production of IL-6 and TNF-α. By contrast, HF did not increase the expression of any co-stimulatory molecules, but also down-modulated CD40 and stimulated the expression of the anti-inflammatory cytokine IL-10. Both parasitic antigens promoted protein synthesis through mTOR activation. The use of rapamycin decreased the expression of the cytokines tested, empowered the down-modulation of CD40 and also reduced splenocyte proliferation. Finally, we showed that E. granulosus antigens increase the amounts of LC3-positive structures in DCs which play critical roles in the presentation of these antigens to T cells.

Abstract 2667: CaMKK2 knockout in mice challenged by orthotopic GBM leads to upregulation of MHC II on TAMs and an increase in accumulation of CD4+ TILs

Abstract Glioblastoma (GBM) is the most lethal primary brain tumor in adults, with the median survival time for GBM patients being only about 15 months. Although immunotherapy treatments have been successful in more immunogenic tumors, it has shown very limited success in GBM. This could be because it is difficult for T cells to infiltrate the tumor, and the tumors have a very immunosuppressive tumor microenvironment (TME) that can often consist of up to about 30 percent tumor associated macrophages (TAMs) by mass. Thus, two ways of possibly improving immunotherapy treatments on GBMs would be to increase the number of tumor infiltrating lymphocytes (TILs) present, and to target tumor-supportive cells such as TAMs. Calmodulin Dependent Protein Kinase Kinase 2 (CaMKK2) is a gene that has been shown to be highly expressed in myeloid cells and is known to alter their phenotype. Recent studies in breast cancer have shown that myeloid cells adopt a more immunostimulatory phenotype in murine knockout CaMKK2 models. However, it is not well understood how CaMKK2 causes this immunosuppressive effect and warrants further exploration. The data from our experiments help to answer this question. High-dimensional flow cytometry with 15 parameters was used in order to determine the identities of immune cells found in the tumor of wildtype and CaMKK2-/- mice. The results of our experiments show that there appear to be more CD4+ TILs present in the TME of knockout mice and that there is an increase in MHC II expression on TAMs found in knockout mice. Since CD4+ TILs recognize peptides presented on MHC II molecules, and there is an increase in the number of CD4+ TILs and expression of MHC II on TAMs in knockout mice, we hypothesize that a stronger immune response could be instigated against the tumor. Therefore, it can be concluded that a possible reason that knocking out CaMKK2 leads to a less immunosupressive TME is because MHC II expression on TAMs is upregulated, and the number of CD4+ TILs in the TME is increased. Whether or not the increase in MHC II expression causes the increase in the number CD4+ TILs requires further exploration. This makes CaMKK2 a promising therapeutic target to treat tumors with immunosuppressive TMEs such as GBM. Citation Format: Molly A. Chakraborty, William H. Tomaszewski, Jessica Waibl Polania, Lauren S. Riley, Luigi Racioppi, Luis A. Sanchez-Perez, John H. Sampson. CaMKK2 knockout in mice challenged by orthotopic GBM leads to upregulation of MHC II on TAMs and an increase in accumulation of CD4+ TILs [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2667.