Myeloid-derived Suppressor Cells Research Articles

Myeloid-derived suppressor cells inhibit responses of T follicular helper cells during experimental Plasmodium yoelii infection.

Malaria remains a significant global public health problem. T follicular helper (Tfh) cells, a subset of CD4+ T cells, have the capacity to regulate B cells, plasma cells, and antibody production, among other functions. Myeloid-derived suppressor cells (MDSCs) possess strong immunosuppressive abilities and can negatively regulate various immune responses. However, the role of MDSCs in inhibiting Tfh-cell responses during Plasmodium infection remains unclear. In this study, we investigated the regulatory effect of MDSCs on Tfh cell-mediated immune responses upon Plasmodium infection. We found that the numbers of MDSCs increased upon Plasmodium infection. Further mechanism study revealed that MDSC-derived Arg-1 and PD-L1 prevented Tfh cell proliferation and activation. Conversely, the addition of nor-NOHA or anti-PD-L1 monoclonal antibodies enhanced the proliferation and activation of Tfh cells, indicating that the inhibitory effect of MDSCs on Tfh cells was dependent on Arg-1 and PD-1/PD-L1. Invivo depletion of MDSCs enhanced Tfh-cell responses and antibody production, as well as relieved symptoms of infected mice and improved their survival rates. These findings provide insights into the immunosuppressive role of MDSCs in inhibiting Tfh cell immune responses and further impairing humoral immunity. Our study provides new strategies for malaria prevention and control.

Denfivontinib activates effector T-cells through NLRP3-inflammasome, yielding potent anticancer effects by combination with pembrolizumab.

Various combination therapies have been investigated to overcome the limitations of using immune checkpoint inhibitors. However, determining the optimal combination therapy remains challenging. To overcome the therapeutical limitation, we conducted a translational research to elucidate the mechanisms by which AXL inhibition enhances the anti-tumor effects when combined with anti-PD-1 antibody therapy. Herein, we demonstrated improved antitumor effects through combination treatment with denfivontinib and pembrolizumab which resulted in enhanced differentiation into effector CD4+ and CD8+ memory T cells, accompanied by an increase in IFN-γ expression in the YHIM-2004 xenograft model derived from patients with NSCLC. Concurrently, a reduction in the number of immunosuppressive M2 macrophages and myeloid-derived suppressor cells was observed. Mechanistically, denfivontinib potentiated the NOD-like receptor pathway, thereby facilitating the NLRP3 inflammasome formation. This leads to macrophage activation via the NF-kB signaling pathway activation. We have confirmed that the positive interaction between macrophages and T cells arises from the enhanced antigen-presenting machinery of activated macrophages. Furthermore, the observed tumor effects in AXL knock-out mice confirmed that AXL inhibition by denfivontinib enhances the anti-tumor effects, thus opening new avenues for therapeutic interventions aimed at overcoming limitations in immunotherapy. To demonstrate the extent to which our findings reflect clinical results, we analyzed bulk-RNA sequencing data from 21 NSCLC patients undergoing anti-PD-1 immunotherapy. The NLRP3 inflammasome score influenced enhanced immune responses in patient data undergoing anti-PD-1 immunotherapy, suggesting a role for NLRP3 inflammasome in activating immune responses during treatment.

Blood immune profiling of Ethiopian patients with breast cancer highlights different forms of immune escape

ABSTRACT Breast cancer (BC) is a leading cause of death worldwide, particularly also among African woman. In order to better stratify patients for the most effective (immuno-) therapy, an in depth characterization of the immune status of BC patients is required. In this study, a cohort of 65 Ethiopian patients with primary BC underwent immune profiling by multicolor flow cytometry on peripheral blood samples collected prior to surgery and to any other therapy. Comparison with peripheral blood samples from healthy donors highlighted a general activation of the immune system, accompanied by the presence of exhausted CD4+ T cells and senescent CD8+ T cells with an inverted CD4/CD8 ratio in approximately 50% of BC cases. Enhanced frequencies of γδ T cells, myeloid-derived suppressor cells and regulatory T cells were also found. Correlation with clinical parameters demonstrated a progressive reduction in T cell frequencies with increasing histopathological grading of the tumor. Differences in CD8+ T cells and B cells were also noted among luminal and non-luminal BC subtypes. In conclusion, Ethiopian BC patients showed several alterations in the composition and activation status of the blood immune cell repertoire, which were phenotypically associated with immune suppression. The role of these immunological changes in the clinical outcome of patients with BC will have to be determined in follow-up studies and confirmed in additional patients’ cohorts.

Network Pharmacology and Bioinformatics Analyses Identify the Core Genes and Pyroptosis-Related Mechanisms of Nardostachys Chinensis for Atrial Fibrillation.

Nardostachys chinensis is an herbal medicine widely used in the treatment of atrial fibrillation (AF), but the mechanism is unclear. To explore the molecular mechanism of N. chinensis against AF. The TCMSP was used to screen the active N. chinensis compounds and their targets. Differentially expressed genes (DEGs) for AF were identified using open-access databases. Using Venn diagrams, the cross-targets of N. chinensis, pyroptosis, and AF were obtained. The genes underwent molecular docking as well as gene set enrichment analysis (GSEA). A nomogram based on candidate genes was constructed and evaluated with the clinical impact curve. After that, the immune infiltration of the dataset was analyzed by single sample GSEA (ssGSEA). Finally, microRNAs (miRNAs) and transcription factors (TFs) were predicted based on candidate genes. Tumor necrosis factor (TNF) and caspase-8 (CASP8) were obtained as candidate genes by taking the intersection of DEGs, targets of N. chinensis, and pyroptosis-related genes. Tolllike receptor (TLR) and peroxisome proliferator-activated receptor (PPAR) signaling pathways were linked to candidate genes. Additionally, immune cell infiltration analysis revealed that CASP8 was associated with natural killer T cells, natural killer cells, regulatory T cells (Tregs), myeloid-derived suppressor cells (MDSC), macrophages, CD8 T cells, and CD4 T cells. Finally, miR-34a-5p and several TFs were found to regulate the expression of CASP8 and TNF. CASP8 and TNF are potential targets of N. chinensis intervention in pyroptosisrelated AF, and the TLR/NLRP3 signaling pathway may be associated with this process.

Deregulation of Casein Kinase-2 in non-small-cell lung cancer: A subunit-specific analysis

Casein kinase-2 (CK2) is a constitutively active kinase that supports neoplastic properties. Although there is an extensive body of preclinical research on CK2, translational and clinical information remains limited and sparse. In this study, we interrogated clinical multiomics databases to examine CK2 deregulation across various cancers. Specifically, we analyzed the mutational frequency, copy-number alterations (CNA), and mRNA expression of CK2 catalytic (CSNK2A1 and CSNK2A2) and regulatory (CSNK2B) subunits across two major cancer genomic repositories (The Cancer Genome Atlas/International Cancer Genome Consortium). These genomic and transcriptomic analyses were further focused on lung cancer and complemented by in situ assessments of CK2 protein subunits and enzymatic activity in biopsies from non-small-cell lung cancer (NSCLC). Our findings indicate that gene mutations and CNA do not account for the elevated mRNA levels and enzymatic activity of CK2 subunits in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC). Particularly, the upregulation of CSNK2A1 and CSNK2B mRNA was associated with a worse prognosis and showed a direct correlation with the infiltration of myeloid-derived suppressor cells in LUAD. At the protein levels, all CK2 subunits and enzymatic activity were markedly elevated in LUAD (n = 103) and LUSC (n = 31) biopsies; however, only CSNK2A1 expression correlated positively with tumor size and disease stage. Finally, CSNK2A1 appeared to be more tumor-specific than CSNK2A2, suggesting that targeted therapies against this catalytic subunit or its homotetramer may offer a more favorable therapeutic window in NSCLC.

Hyperactivity of the IL-33-ILC2s-IL-13-M-MDSCs axis promotes cervical cancer progression

The interleukin-33(IL-33) – group 2 innate lymphoid cells (ILC2s) – interleukin-13(IL-13) – monocytic myeloid-derived suppressor cells (M-MDSCs) axis plays a critical role in promoting immune evasion in tumors; however, its specific function in cervical cancer remains poorly understood. In this study, we observed that the proportion of IL-33-ILC2s-IL-13-M-MDSCs were significantly elevated in both cervical cancer patients and the subcutaneous U14 cervical cancer mouse model, compared to normal controls. Our results suggest that IL-33 stimulates ILC2s to secrete IL-13, which, in turn, regulates M-MDSCs to enhance their immune evasion capabilities. Notably, in vitro blockade of IL-33 and IL-13 partially restored the levels and functions of both ILC2s and M-MDSCs. In conclusion, these findings imply that the overactivation of the IL-33-ILC2s-IL-13-M-MDSCs axis may contribute to cervical cancer progression. However, further in vivo blockade studies are required to fully elucidate the precise mechanisms underlying this interaction and to assess its potential therapeutic implications for cervical cancer.

A Pan-Cancer Analysis of the Oncogenic Role of CD276 in Human Tumors

Objectives: B7 homolog 3 protein (B7-H3, also known as CD276) is a member of the B7 family that has been found to be associated with the growth and progression of a variety of tumors, but no pan-cancer evaluations of CD276 have been performed so far. In this study, we aimed to perform a pan-cancer analysis of the oncogenic role of CD276 in human tumors; Methods: We used a series of databases to perform a pan-cancer analysis of CD276, including the expression level of CD276 in pan-cancer and its relationship to tumor progression, patient survival duration, the immune cell infiltration within the tumor, and the potential signaling pathways and molecular mechanisms associated with CD276; Results: We found that CD276 was a potential biomarker for the prognosis of most cancers. The high expression of CD276 was associated with tumor progression, leading to poor survival. Notably, the up-regulation of CD276 expression in tumors increased the tumor infiltration of cancer-associated fibroblasts (CAFs) and myeloid-derived suppressor cells (MDSCs) and decreased the CD8+ T cells; Conclusions: Our study demonstrates that CD276 might promote tumor progression via the promotion of an immunosuppressive microenvironment.

The Association between Systemic Inflammation and the Prostate Cancer: based on the National Health and Nutrition Examination Survey and Mendelian Randomization Analysis.

The purpose of this combination research was to examine the relationship between systemic inflammation and the risk of prostate cancer (PCa) through the National Health and Nutrition Examination Survey (NHANES) cross-sectional study and two-sample Mendelian randomization (MR) analysis. We incorporated NHANES data spanning the years 2001 to 2010, with exposure as systemic inflammation, evaluated using systemic immune-inflammation index (SII) and outcome as PCa, and performed multivariate logistic regression and restricted cubic spline (RCS) to test the correlation between SII and PCa. Further, two-sample MR was used to identify causal associations between specific immune cells and PCa. A total of 7706 participants (age≥40 years) were included in the analysis in the cross-sectional study, including 350 PCa cases, 7356 controls. Higher SII levels were associated with increased odds of PCa (P<.05). The odds ratio (OR) for PCa was 1.51 (95% CI 1.09-2.08) for the highest versus lowest quartile of SII levels in the fully adjusted model. Also, the RCS analysis showed a threshold effect, with SII levels above 8.90 associated with increased odds of PCa. In addition, MR results suggested a causal relationship between CD62L- monocyte, CD62L- HLA DR+ monocyte, CD14+ CD16+ monocyte, CD62L- Dendritic Cell, Monocytic Myeloid-Derived Suppressor Cell, CD28- CD8dim T cell, CD39+ resting CD4 regulatory T cell and PCa (P<.05). This combination analysis provides evidence for a significant causal relationship between systemic inflammation and PCa risk. These findings highlight systemic inflammation and inflammatory immune responses as potential modifiable risk factors for PCa.

Exploring RPA1-ETAA1 axis via high-throughput data analysis: implications for PD-L1 nuclear translocation and tumor-immune dynamics in liver cancer

IntroductionETAA1 is recruited to DNA damage sites via its RPA -binding and ATR -activating domain (AAD) motifs, where RPA binding is crucial for ETAA1’s regulation of ATR activity. Methods &amp;amp; resultsOur findings associate Programmed Death- Ligand1 (PD-L1) with the RPA1-ETAA1 axis, suggesting that upregulated RPA1 -dependent ETAA1 may facilitate PD-L1 nuclear accumulation. We observed strong correlations between ETAA1 and RPA1 with the components involved in HDAC2-mediated deacetylation, clathrin -dependent endocytosis, and PD-L1 nucleocytoplasmic shuttling, aligning with the established regulatory pathway of PD-L1 nuclear translocation. Moreover, nuclear PD-L1 transactivates a panel of pro-inflammatory and immune response transcription factors, potentially reshaping the tumor immune microenvironment. We identified a landscape of infiltrating lymphocytes influenced by ETAA1, finding that levels of ETAA1 were negatively correlated with CD8+ T and Natural Killer T (NKT) cells, but positively correlated with CD4+ T helper 2 (Th2) cells, cancer-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), neutrophils and regulatory T cells (Tregs), suggesting a potential role in immune evasion. Further analysis shows that the RPA1-ETAA1 axis is significantly associated with multiple metastasis mediators and unfavorable liver cancer progression, with higher expression observed in advanced stages and poorly differentiated subgroups. Discussion &amp;amp; conclusionThese findings expand the role of the RPA1-ETAA1 axis beyond DNA repair, highlighting its potential as a target for cancer therapy.

Lactate: a rising star in tumors and inflammation

Lactate has been traditionally regarded as a mere byproduct of glycolysis or metabolic waste. However, an increasing body of literature suggests its critical role in regulating various physiological and pathological processes. Lactate is generally associated with hypoxia, inflammation, viral infections, and tumors. It performs complex physiological roles by activating monocarboxylate transporter (MCT) or the G protein-coupled receptor GPR81 across the cell membrane. Lactate exerts immunosuppressive effects by regulating the functions of various immune cells (such as natural killer cells, T cells, dendritic cells, and monocytes) and its role in macrophage polarization and myeloid-derived suppressor cell (MDSC) differentiation in the tumor microenvironment. Lactic acid has also recently been found to increase the density of CD8+ T cells, thereby enhancing the antitumor immune response. Acute or chronic inflammatory diseases have opposite immune states in the inflammatory disease microenvironment. Factors such as cell types, transcriptional regulators, ionic mediators, and the microenvironment all contribute to the diverse functions lactate exhibits. Herein, we reviewed the pleiotropic effects of lactate on the regulation of various functions of immune cells in the tumor microenvironment and under inflammatory conditions, which may help to provide new insights and potential targets for the diagnosis and treatment of inflammatory diseases and malignancies.

Immunotherapy in the Battle Against Bone Metastases: Mechanisms and Emerging Treatments

Bone metastases are a prevalent complication in advanced cancers, particularly in breast, prostate, and lung cancers, and are associated with severe skeletal-related events (SREs), including fractures, spinal cord compression, and debilitating pain. Conventional bone-targeted treatments like bisphosphonates and RANKL inhibitors (denosumab) reduce osteoclast-mediated bone resorption but do not directly impact tumor progression within the bone. This review focuses on examining the growing potential of immunotherapy in targeting the unique challenges posed by bone metastases. Even though immune checkpoint inhibitors (ICIs) have significantly changed cancer treatment, their impact on bone metastases appears limited because of the bone microenvironment’s immunosuppressive traits, which include high levels of transforming growth factor-beta (TGFβ) and the immune-suppressing cells, such as regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs). This review underscores the investigation of combined therapeutic approaches that might ease these difficulties, such as the synergy of immune checkpoint inhibitors with agents aimed at bones (denosumab, bisphosphonates), chemotherapy, and radiotherapy, as well as the combination of immune checkpoint inhibitors with different immunotherapeutic methods, including CAR T-cell therapy. This review provides a comprehensive analysis of preclinical studies and clinical trials that show the synergistic potential of these combination approaches, which aim to both enhance immune responses and mitigate bone destruction. By offering an in-depth exploration of how these strategies can be tailored to the bone microenvironment, this review underscores the need for personalized treatment approaches. The findings emphasize the urgent need for further research into overcoming immune evasion in bone metastases, with the goal of improving patient survival and quality of life.

FCGBP functions as a tumor suppressor gene in head and neck squamous cell carcinoma

PurposeThe pathogenesis of head and neck squamous cell carcinoma (HNSCC) was complex and the overall survival was not satisfying. It was urgent to uncover novel molecules that play vital role in HNSCC for disease monitoring and drug development.MethodsDistinguished expression of FCGBP mRNA in HNSCC was analyzed by TCGA-HNSC and three GEO datasets, the relationship between FCGBP and clinical stage and survival was analyzed by GEPIA 2, the immune infiltration pattern analysis was conducted by TIMER 2.0, pathways affected by FCGBP was conducted by GSEA and GO/KEGG. In vitro experiments (including qRT-PCR, siRNA transfection, CCK8, transwell assay and flow cytometry) were conducted to confirm bioinformatic analysis.ResultsFCGBP was down-regulated in tumor samples compared with normal tissues at both mRNA and protein levels, and positively correlated with survival in HNSCC. Genes co-expressed with FCGBP were mainly enriched in immune-related biological processes and pathways. GSEA indicated that FCGBP was associated with activated immune reaction and inhibiting well-known pro-tumor pathways. GSE41613 validated FCGBP as an independent prognostic marker for HNSCC and FCGBP was down-regulated in HNSCC cell lines by qRT-PCR. Migration and invasion of SCC9 and CAL27 were enhanced by FCGBP-targeting siRNAs, the ratio of cytotoxic T lymphocytes were down-regulated while the ratio of myeloid-derived suppressor cells were increased by FCGBP-targeting siRNAs.ConclusionFCGBP was a tumor suppressor gene and was an independent prognostic marker for better survival. The underlying mechanism may be that FCGBP inhibited tumor migration and invasion and activated immune response against tumor cells.

Correlation of the abundance of MDSCs, Tregs, PD-1, and PD-L1 with the efficacy of chemotherapy and prognosis in gastric cancer.

The aim of this study was to investigate the relationship between tumor microenvironment markers (myeloid-derived suppressor cells [MDSCs], regulatory T cells [Tregs], programmed cell death 1 [PD-1], and programmed death ligand 1 [PD-L1]) and chemotherapy efficacy and prognosis in advanced gastric cancer, identifying potential monitoring indicators. Advanced gastric cancer patients' MDSC and Treg expression was measured by flow cytometry pre- and postchemotherapy; PD-1 and PD-L1 expression in cancer tissues was assessed by immunohistochemistry. Correlations with chemotherapy outcomes and prognosis were analyzed. Postchemotherapy reductions in MDSC and Treg levels correlated with chemotherapy efficacy (P <.01). Negative PD-1 and PD-L1 expression in cancer tissues predicted better chemotherapy responses (P <.01). Patients with lower MDSC and Treg levels and negative PD-1 and PD-L1 had significantly longer median progression-free survival (PFS) and overall survival (OS) (P <.05). In advanced gastric cancer, reduced peripheral blood MDSC and Treg levels postchemotherapy and negative PD-1 and PD-L1 expression in tissues are associated with improved chemotherapy efficacy and are independent prognostic factors for PFS and OS.

Emerging Role of Extracellular pH in Tumor Microenvironment as a Therapeutic Target for Cancer Immunotherapy.

Identifying definitive biomarkers that predict clinical response and resistance to immunotherapy remains a critical challenge. One emerging factor is extracellular acidosis in the tumor microenvironment (TME), which significantly impairs immune cell function and contributes to immunotherapy failure. However, acidic conditions in the TME disrupt the interaction between cancer and immune cells, driving tumor-infiltrating T cells and NK cells into an inactivated, anergic state. Simultaneously, acidosis promotes the recruitment and activation of immunosuppressive cells, such as myeloid-derived suppressor cells and regulatory T cells (Tregs). Notably, tumor acidity enhances exosome release from Tregs, further amplifying immunosuppression. Tumor acidity thus acts as a "protective shield," neutralizing anti-tumor immune responses and transforming immune cells into pro-tumor allies. Therefore, targeting lactate metabolism has emerged as a promising strategy to overcome this barrier, with approaches including buffer agents to neutralize acidic pH and inhibitors to block lactate production or transport, thereby restoring immune cell efficacy in the TME. Recent discoveries have identified genes involved in extracellular pH (pHe) regulation, presenting new therapeutic targets. Moreover, ongoing research aims to elucidate the molecular mechanisms driving extracellular acidification and to develop treatments that modulate pH levels to enhance immunotherapy outcomes. Additionally, future clinical studies are crucial to validate the safety and efficacy of pHe-targeted therapies in cancer patients. Thus, this review explores the regulation of pHe in the TME and its potential role in improving cancer immunotherapy.

Etomoxir Sodium Salt Promotes Imidazole Ketone Erastin-Induced Myeloid-Derived Suppressor Cell Ferroptosis and Enhances Cancer Therapy.

Although ferroptosis inducers trigger ferroptotic tumor cells and immune cells in the tumor microenvironment (TME), imidazole ketone erastin (IKE)'s induction of ferroptosis shows no effect on tumor growth in immunocompetent tumor-bearing mice due to the presence of myeloid-derived suppressor cells (MDSCs). Treatment of the carnitine palmitoyltransferase 1a (CPT1A)-specific inhibitor decreases the immunosuppressive function of MDSCs and enhances ferroptotic inducer-initiated tumor cell ferroptosis. However, whether blocking CPT1A could enhance IKE-induced MDSC ferroptosis and thereby inhibit tumor growth is still unclear. Here, we report that a CPT1A-specific inhibitor, etomoxir sodium salt (Eto), and IKE combined treatment increased MDSC ferroptosis. Interestingly, the combination treatment of Eto and IKE blocked MDSCs' immunosuppressive function and accumulation by downregulating the expression of SLC7A11, GPX4, and ARG1 while promoting T-cell proliferation and infiltration into tumor tissues to enhance cancer therapy. These data provide a rationale for the combination therapy of a specific CPT1A inhibitor, Eto, with IKE in clinical settings.

Platelet-activating factor: a potential therapeutic target to improve cancer immunotherapy.

The tumor microenvironment (TME) fosters cancer progression by supporting the differentiation and proliferation of myeloid-derived suppressor cells (MDSCs), which play a critical role in suppressing immune responses and facilitating tumor growth. Recent findings by Dahal etal. reveal that platelet-activating factor (PAF), a lipid mediator elevated in the TME, contributes to the differentiation of neutrophils into immunosuppressive neutrophils. They showed that inhibiting PAF signaling reduces MDSC-mediated immunosuppression, thereby enhancing cytotoxic T-cell activity. This approach may improve cancer immunotherapy outcomes, particularly when combined with checkpoint blockade therapies, suggesting a promising avenue for therapeutic development.

Abstract B046: Pyk2 and MEK/ERK signaling regulate the extracellular vesicle release and tumor-associated myeloid Cells in glioblastoma

Abstract Glioblastoma (GBM) is often fatal within a year despite treatment, with immune checkpoint blockade therapies benefiting only about 10% of patients. Non-responsive GBMs exhibit an immunosuppressive profile and higher levels of tumor-associated myeloid cells (TAMs). Addressing this immunosuppressive microenvironment is a major challenge in GBM immunotherapy. Our recent studies have identified a positive correlation between Proline-Rich Tyrosine Kinase 2 (Pyk2) activation in GBM tumor cells and the cytokine expression profile of TAMs. This identified Pyk2 as a potential prognostic marker for the immune state in GBM tumor microenvironment. We hypothesize that Pyk2 and MEK/Erk signaling in GBM cells regulate the release of chemokines and cytokines through extracellular vesicles (EVs) by modulating the actin cytoskeleton, thereby impacting TAM activation. The study aimed to investigate the role of Pyk2/MEK/Erk signaling in EV release in GBM cells, potentially revealing new therapeutic targets. Two humans primary GBM cell lines, with and without Pyk2 CRISPR/Cas9 knockout (Pyk2KO), were used. Flow cytometric analysis of EVs, enriched from cell-conditioned medium, identified a shift towards larger in diameter EVs populations in Pyk2 KO cells, compared to wild-type (WT) cells. Analysis using Integrin as a plasma membrane marker showed that 84.70% of Integrin+ and 15.30% of Integrin- EVs were derived from WT cells, whereas Pyk2KO cells produced 89.07% Integrin+ and 10.93% Integrin- EVs. Treatment of WT cells with the Erk/MEK inhibitor Avutometinib (1µM) altered the EV population’s ratio to 79.11% Integrin+ and 20.89% Integrin-. Similarly, Avutometinib treatment of Pyk2KO cells resulted in 78.83% Integrin+ and 21.17% Integrin- EVs, similar to the ratio observed in Avutometinib-treated WT cells. Western blot and PCR analysis of EVs content revealed a significant reduction in CCL2, CCL5, tumor necrosis factor (TNF), and vascular endothelial growth factors (VEGF) in EVs from Pyk2KO GBM cells, compared to WT. In vivo studies using GL261/C57Bl/6 mouse glioma implantation model and flow cytometric analysis of TAMs from tumors generated with WT and Pyk2KO GL261 cells demonstrated increased infiltration of TNF+/IFNg+ CD8+ lymphocytes and Ly6C+/CD206- myeloid cells, alongside a reduction in CD45+/CD11b+/CD33+/MHCII- myeloid-derived suppressor cells. PCR analysis of TAM isolated from Pyk2KO tumors revealed lower gene expression of TNF, CCL5, CCL2, VEGFa, and epidermal growth factor (EGF) compared to WT tumors. The study highlights that Pyk2/MEK/Erk signaling regulates the immune microenvironment in GBM by influencing EV release, which impacts TAM cell activation. Pyk2 primarily regulates the release of Integrin- EVs, while MEK/Erk predominantly regulates EVs shed from the plasma membrane. The findings underscore the interplay between Pyk2 and MEK/Erk signaling in regulating EV biogenesis and composition. Citation Format: Neisha M. Ramirez. Pyk2 and MEK/ERK signaling regulate the extracellular vesicle release and tumor-associated myeloid Cells in glioblastoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B046.

Investigating disturbances of the core material system in the lung-gut axis of COPD based on the transcriptomics-metabolomics-microbiomics integration strategy

BackgroundAlthough still the significance of the lung-gut axis for COPD is increasingly highlighted, it’s urgent to ulteriorly comprehend the sophisticated disturbance of the core material system along the lung-gut axis, which is of great importance for the accurate precaution and prognosis of COPD efficiently. Aim of the studyThe purpose of this study was to analyze the information connections of the lung-gut axis, thus supporting the effective treatment of COPD. Materials and methodsAn integrated multi-omics approach was applied to explore the lung-gut axis in COPD rats. Firstly, based on transcriptomics, the ssGSEA algorithm was used to evaluate changes in pulmonary inflammatory cells. Then, the disturbances of metabolic pathways in lung and feces were revealed by the Lilikoi algorithm using LC-MS and 1H NMR metabolomics. Next, the composition and function of microbial communities in lung and feces were analyzed by 16 s rRNA sequencing. Finally, the association analysis was employed to explore the possible crosstalk between the lung and gut. Furthermore, the core material system in the lung-gut axis was described based on network topology analysis. ResultFirstly, 1652 differential expression genes (involving in immune response-regulating signaling pathway, etc.) and 15 types of inflammatory cells (including neutrophil, etc.) were identified related to COPD. 135 pulmonary differential metabolites (involving in arachidonic acid metabolism, etc.) and 105 fecal differential metabolites (involving in alanine metabolism, etc.) were revealed by metabolomics. The f_Pasteurellaceae, etc. and g_Ruminococcus_2, etc. were identified associated with COPD in lung and gut. Finally, disturbances of the core material system, composed of macrophage, neutrophil, activated dendritic cell, myeloid derived suppressor cell, arachidonic acid metabolism, alpha linolenic acid & linoleic acid metabolism, g_Psychrobacter in lung and bile secretion, p_Proteobacteria in gut, were obtained to analyze the possible information flow of the lung-gut axis. ConclusionThe core material system for the lung-gut axis have been revealed, which might contribute to the illustration of the pathogenesis of COPD. In the future, more researches are required on the impact of the core material system in the lung-gut axis on the onset and recovery process of COPD, suggesting more precise identifying effective treatments for the disease.

Abstract B040: Investigating the impact of tumor EMT states on immune cell infiltration in breast cancer

Abstract Breast cancer is one of the most frequently diagnosed cancers and the second leading cause of women’s cancer death. Although the five-year survival rate for women in the United States with nonmetastatic invasive breast cancer is 90%, this rate drops to less than 30% for those with tumors that have metastasized to distant organs. Epithelial-to-Mesenchymal Transition (EMT) plays a critical role in tumor metastasis by enabling the loss of epithelial characteristics and the gain of mesenchymal traits, leading to increased cell motility, invasion, and resistance to therapy. Consequently, targeting the EMT process may prevent tumor cell migration and improve patient outcomes. Rather than being a binary switch from an epithelial to a mesenchymal state, cells undergoing EMT can assume a spectrum of intermediate states, some of which may reshape the tumor microenvironment by recruiting pro-tumor immunosuppressive cells, such as regulatory T cells, M2-like macrophages, and myeloid-derived suppressor cells. However, the impact of EMT on the immune composition of the tumor microenvironment and the causative mechanisms remain poorly understood. Using multi-omics approaches in a mouse model of triple-negative breast cancer, we assessed the interaction between tumor and immune cells in the tumor microenvironment driven by the EMT. A heterogeneous mouse breast cancer cell line (4T1) was used to isolate five distinct single-cell-derived clonal populations residing in distinct states within the EMT spectrum. These EMT clones, along with the parental 4T1 cell line, were orthotopically transplanted into the mammary fat pads of BALB/c mice. Primary tumors were subsequently harvested and dissociated for single-cell RNA-sequencing (scRNA-seq) and DNA methylation analysis. Lungs were histologically evaluated for metastases. Tumors derived from an intermediate EMT clone exhibited increased tumor growth kinetics and a higher incidence of metastasis compared to epithelial or mesenchymal clones. In scRNA-seq data, tumors derived from different EMT clones largely retained their original EMT states in vivo and recruited distinct immune cell profiles. DNA methylation analysis further revealed that these tumors displayed unique methylation patterns in EMT-related CpGs. This study introduced a model that captures the complexity of the tumor microenvironment across the EMT spectrum. This was accomplished through immunophenotyping using scRNA-seq and identifying unique epigenetic patterns through DNA methylation. Our findings highlight the potential for distinct immune cell populations to be recruited to tumors in different EMT states, thereby influencing survival and metastasis outcomes. Furthermore, our results open new opportunities for developing cancer combination treatment strategies that target specific tumor-immune cell interactions. Citation Format: Hanxu Lu, Meisam Bagheri, Todd Miller, Diwakar Pattabiraman, Brock Christensen. Investigating the impact of tumor EMT states on immune cell infiltration in breast cancer [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr B040.

Abstract A003: The role of aging in promoting immune mediated reactivation from metastatic melanoma dormancy

Abstract Metastasis is the primary cause of melanoma death. A major problem with the vast majority of previous studies is that young mice (8-weeks old, equivalent to 20 human years) are used to investigate the mechanisms of metastatic outgrowth, whereas the median age of melanoma diagnosis in humans is ∼65 years. Advanced age also correlates with metastasis, mortality, and immune dysfunction. Moreover, most studies often only focus on lung metastases, despite melanoma commonly metastasizing to sites such as the liver in patients, which are significantly more resistant to checkpoint inhibitors (ICIs) compared to patients with lung metastases. We have begun addressing these core limitations by developing novel syngeneic mouse models of melanoma metastasis and colonization in young (8-week), middle-aged (12-month), and geriatric (18-22 month) mice, in which metastatic colonization/dissemination can be targeted to either the lung or liver alone, or to both simultaneously. Our data now show that aging promotes reactivation of dormant tumor cells and subsequent outgrowth of lung and liver metastases. We have found that frontline innate lymphocytes such as NK-cells and γδ T-cells are decreased in the pre-metastatic lung and livers of aged mice relative to young mice and remain decreased during early and late-stage metastasis. Using inducible KO mouse models and antibody depletion methods in young growth restrictive mice, we find that depletion of either NK-cells or γδ T-cells is sufficient to promote reactivation from dormancy and resistance to anti-PD1 therapy. Secondly, we further delineated changes in the post-metastatic lung and liver niche. We find that PROS1 secretion by reactivated melanoma cells expressing high levels of the MER tyrosine kinase receptor (MER) in the aged metastatic lung and liver increases CD11b myeloid cells expressing the immunosuppressive factor ARG1. Within this CD11b subset, we see an increase in polymorphonuclear myeloid derived suppressor cells (PMN MDSCs). Treatment with recombinant ARG1 promotes reactivation from dormancy in young mice whilst depletion of PMN MDSCs inhibits age induced outgrowth in the lung and liver. Overall, our study highlights common immune-mediated age-related changes in the pre and post metastatic lung and liver which contribute to aggressive metastatic initiation, reactivation from dormancy, progression, and resistance to anti-PD1 Citation Format: Kelly Coutant, Jhon Passamonte, Christopher Price, Pulkit Datt, Mitchell Fane. The role of aging in promoting immune mediated reactivation from metastatic melanoma dormancy [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr A003.