Immunosuppressive Potential Research Articles

Enhancing intrinsic TGF-β signaling via heparan sulfate glycosaminoglycan regulation to promote mesenchymal stem cell capabilities and chondrogenesis for cartilage repair

Osteoarthritis burdens patients due to the limited regenerative capacity of chondrocytes. Traditional cartilage repair often falls short, necessitating innovative approaches. Mesenchymal stem cells (MSCs) show promise for regeneration. Heparan sulfate glycosaminoglycans (HS-GAGs) regulate cellular functions, making them a target for cartilage repair. This study highlights how Heparinase III (HepIII) cleaves intact HS-GAGs in bone marrow-derived MSCs (BM-MSCs), enhancing their capabilities and specifically promoting chondrogenesis. HepIII-treated BM-MSCs cultured in a hanging drop device for three days, significantly increased cell number and aggregation into a cell sphere with early chondrogenesis. HepIII promoted BM-MSCs toward chondrogenesis, increasing type II collagen, intact HS-GAGs, and sulfated GAG content, while upregulating chondrogenic and heparan sulfate proteoglycan genes. Treatment with the TGF-β inhibitor (SB-431542) in HepIII-treated BM-MSCs demonstrated enhanced intrinsic transforming growth factor-β (TGF-β) signaling and fibronectin expression. This approach also boosted BM-MSC self-renewal, immunosuppressive potential, and modified acetylated histone signatures, offering a cost-effective strategy for cartilage repair by addressing inflammation, metabolic changes, and the high costs of traditional TGF-β methods. From the results, HepIII-treated BM-MSCs show potential for use in combination with other biopolymers as injectable gels to improve cartilage repair in osteoarthritis patients in the near future.

Myocardial inflammation is associated with impaired mitochondrial oxidative capacity in ischaemic cardiomyopathy.

Myocardial inflammation and impaired mitochondrial oxidative capacity are hallmarks of heart failure (HF) pathophysiology. The extent of myocardial inflammation in patients suffering from ischaemic cardiomyopathy (ICM) or dilated cardiomyopathy (DCM) and its association with mitochondrial energy metabolism are unknown. We aimed at establishing a relevant role of cardiac inflammation in the impairment of mitochondrial energy production in advanced ischaemic and non-ischaemic HF. We included 81 patients with stage D HF (ICM, n=44; DCM, n=37) undergoing left ventricular assist device implantation (n=59) or heart transplantation (n=22) and obtained left ventricular tissue samples during open heart surgery. We quantified mitochondrial oxidative capacity, citrate synthase activity (CSA) and fibrosis and lymphocytic infiltration. We considered infiltration of >14 CD3+ cells/mm2 relevant inflammation. Patients with ICM or DCM did not differ regarding age (61.5±5.7 vs. 56.5±12.7years, P=0.164), sex (86% vs. 84% male, P=0.725), type 2 diabetes mellitus (34% vs. 18%, P=0.126) or chronic kidney disease (8% vs. 11%, P=0.994). ICM exhibited oxidative capacity reduced by 23% compared to DCM (108.6±41.4 vs. 141.9±59.9pmol/(s*mg), P=0.006). Maximum production of reactive oxygen species was not significantly different between ICM and DCM (0.59±0.28 vs. 0.69±0.36pmol/(s*ml), P=0.196). Mitochondrial content, detected by CSA, was lower in ICM (359.6±164.1 vs. 503.0±198.5nmol/min/mg protein, P=0.002). Notably, relevant inflammation was more common in ICM (27% vs. 6%, P=0.024), and the absolute number of infiltrating leucocytes correlated with lower oxidative capacity (r=-0.296, P=0.019). Fibrosis was more prevalent in ICM (20.9±21.2 vs. 7.2±5.6% of area, P=0.002), but not associated with oxidative capacity (r=-0.13, P=0.327). More than every fourth ICM patient with advanced HF displays myocardial inflammation in the range of inflammatory cardiomyopathy associated with reduced mitochondrial oxidative capacity. Future studies may evaluate inflammation in ICM at earlier stages in standardised fashion to explore the therapeutic potential of immunosuppression to influence trajectories of HF in ICM.

Evaluation of Anti-Inflammatory and Immunosuppressant Potential of Isotelekin in Lipopolysaccharide (LPS) Stimulated Macrophage (RAW 264.7) and Sheep Red Blood Cells (SRBC) Sensitized Murine Models.

The present study explored the natural compound Isotelekin isolated from Inula racemose against anti-inflammatory and immunomodulatory potential in LPS-induced RAW264.7 cell lines and immune-elevated SRBC-sensitized animal models. Isotelekin in in vitro studies, inhibited the production of Th-1 cytokines Interleukin-6 (IL-6), Tumour necrosis factor (TNF-α), and Interferon-gamma (INF-γ),and increased Th-2 cytokines Interleukin-10 (IL-10). Whereas it inhibited the nitrites and reactive oxygen species (ROS) production by mitigating the effect of LPS significantly. In vivo immunomodulatory activity in Delayed-type hypersensitivity (DTH) and Hemagglutinating antibody (HA), Isotelekin suppressed the cellular as well as humoral immunity in immune-affected and SRBC-sensitized mice. Isotelekin decreased the phagocytic responses against carbon particles and plaque-forming mainly IgG (Immunoglobulin G) production. Additionally, Isotelekin showed immunosuppressive potential through the evaluation of splenocytes, allograft acceptance, and haematological parameters. Molecular studies, including western blot analysis and immunocytochemistry, revealed that Isotelekin reduced the expression of iNOS (Inducible nitric oxide synthase), COX-2 (Cyclo-Oxygenase 2), and p-IkBα (Phospho I-kappa-B-alpha), and significantly inhibited the nuclear translocation of NF-κB/p65. Based on these results, Isotelekin at 10 µm in in vitro and at 30mgkg-1 in in vivo demonstrated strong anti-inflammatory and immunosuppressive therapeutic potential.

Phenotypic profiling of human induced regulatory T cells at early differentiation: insights into distinct immunosuppressive potential

Regulatory T cells (Tregs) play a key role in suppressing systemic effector immune responses, thereby preventing autoimmune diseases but also potentially contributing to tumor progression. Thus, there is great interest in clinically manipulating Tregs, but the precise mechanisms governing in vitro-induced Treg (iTreg) differentiation are not yet fully understood. Here, we used multiparametric mass cytometry to phenotypically profile human iTregs during the early stages of in vitro differentiation at single-cell level. A panel of 25 metal-conjugated antibodies specific to markers associated with human Tregs was used to characterize these immunomodulatory cells. We found that iTregs highly express the transcription factor FOXP3, as well as characteristic Treg-associated surface markers (e.g. CD25, PD1, CD137, CCR4, CCR7, CXCR3, and CD103). Expression of co-inhibitory factors (e.g. TIM3, LAG3, and TIGIT) increased slightly at late stages of iTreg differentiation. Further, CD103 was upregulated on a subpopulation of iTregs with greater suppressive capacity than their CD103− counterparts. Using mass-spectrometry-based proteomics, we showed that sorted CD103+ iTregs express factors associated with immunosuppression. Overall, our study highlights that during early stages of differentiation, iTregs resemble memory-like Treg features with immunosuppressive activity, and provides opportunities for further investigation into the molecular mechanisms underlying Treg function.

Using machine learning to classify the immunosuppressive activity of per- and polyfluoroalkyl substances

Per- and polyfluoroalkyl substances (PFASs), one of the persistent organic pollutants, have immunosuppressive effects. The evaluation of this effect has been the focus of regulatory toxicology. In this investigation, 146 PFASs (immunosuppressive or nonimmunosuppressive) and corresponding concentration gradients were collected from literature, and their structures were characterized by using Dragon descriptors. Feature importance analysis and stepwise feature elimination are used for feature selection. Three machine learning (ML) methods, namely Random Forest (RF), Extreme Gradient Boosting Machine (XGB), and Categorical Boosting Machine (CB), were utilized for model development. The model interpretability was explored by feature importance analysis and correlation analysis. The findings indicated that the three models developed have exhibited excellent performance. Among them, the best-performing RF model has an average AUC score of 0.9720 for the testing set. The results of the feature importance analysis demonstrated that concentration, SpPosA_X, IVDE, R2s, and SIC2 were the crucial molecular features. Applicability domain analysis was also performed to determine reliable prediction boundaries for the model. In conclusion, this study is the first application of ML models to investigate the immunosuppressive activity of PFASs. The variables used in the models can help understand the mechanism of the immunosuppressive activity of PFASs, allow researchers to more effectively assess the immunosuppressive potential of a large number of PFASs, and thus better guide environmental and health risk assessment efforts.

Drug repurposing for glomerular diseases: an underutilized resource.

Drug repurposing in glomerular disease can deliver opportunities for steroid-free regimens, enable personalized multi-target options for resistant or relapsing disease and enhance treatment options for understudied populations (for example, children) and in resource-limited settings. Identification of drug-repurposing candidates can be data driven, which utilizes existing data on disease pathobiology, drug features and clinical outcomes, or experimental, which involves high-throughput drug screens. Information from databases of approved drugs, clinical trials and PubMed registries suggests that at least 96 drugs on the market cover 49 targets with immunosuppressive potential that could be candidates for drug repurposing in glomerular disease. Furthermore, evidence to support drug repurposing is available for 191 immune drug target-glomerular disease pairs. Non-immunological drug repurposing includes strategies to reduce haemodynamic overload, podocyte injury and kidney fibrosis. Recommended strategies to expand drug-repurposing capacity in glomerular disease include enriching drug databases with glomeruli-specific information, enhancing the accessibility of primary clinical trial data, biomarker discovery to improve participant selection into clinical trials and improve surrogate outcomes and initiatives to reduce patent, regulatory and organizational hurdles.

Surface-Enhanced Raman Scattering Monitoring of Tryptophan Dynamics in 3D Pancreatic Tumor Models.

In the intricate landscape of the tumor microenvironment, both cancer and stromal cells undergo rapid metabolic adaptations to support their growth. Given the relevant role of the metabolic secretome in fueling tumor progression, its unique metabolic characteristics have gained prominence as potential biomarkers and therapeutic targets. As a result, rapid and accurate tools have been developed to track metabolic changes in the tumor microenvironment with high sensitivity and resolution. Surface-enhanced Raman scattering (SERS) is a highly sensitive analytical technique and has been proven efficient toward the detection of metabolites in biological media. However, profiling secreted metabolites in complex cellular environments such as those in tumor-stroma 3D in vitro models remains challenging. To address this limitation, we employed a SERS-based strategy to investigate the metabolic secretome of pancreatic tumor models within 3D cultures. We aimed to monitor the immunosuppressive potential of stratified pancreatic cancer-stroma spheroids as compared to 3D cultures of either pancreatic cancer cells or cancer-associated fibroblasts, focusing on the metabolic conversion of tryptophan into kynurenine by the IDO-1 enzyme. We additionally sought to elucidate the dynamics of tryptophan consumption in correlation with the size, temporal evolution, and composition of the spheroids, as well as assessing the effects of different drugs targeting the IDO-1 machinery. As a result, we confirm that SERS can be a valuable tool toward the optimization of cancer spheroids, in connection with their tryptophan metabolizing capacity, potentially allowing high-throughput spheroid analysis.

A distinct subset of urothelial cells with enhanced EMT features promotes chemotherapy resistance and cancer recurrence by increasing COL4A1-ITGB1 mediated angiogenesis

Drug resistance and tumor recurrence remain clinical challenges in the treatment of urothelial carcinoma (UC). However, the underlying mechanism is not fully understood. Here, we performed single-cell RNA sequencing and identified a subset of urothelial cells with epithelial-mesenchymal transition (EMT) features (EMT-UC), which is significantly correlated with chemotherapy resistance and cancer recurrence. To validate the clinical significance of EMT-UC, we constructed EMT-UC like cells by introducing overexpression of two markers, Zinc Finger E-Box Binding Homeobox 1 (ZEB1) and Desmin (DES), and examined their histological distribution characteristics and malignant phenotypes. EMT-UC like cells were mainly enriched in UC tissues from patients with adverse prognosis and exhibited significantly elevated EMT, migration and gemcitabine tolerance in vitro. However, EMT-UC was not specifically identified from tumorous tissues, certain proportion of them were also identified in adjacent normal tissues. Tumorous EMT-UC highly expressed genes involved in malignant behaviors and exhibited adverse prognosis. Additionally, tumorous EMT-UC was associated with remodeled tumor microenvironment (TME), which exhibited high angiogenic and immunosuppressive potentials compared with the normal counterparts. Furthermore, a specific interaction of COL4A1 and ITGB1 was identified to be highly enriched in tumorous EMT-UC, and in the endothelial component. Targeting the interaction of COL4A1 and ITGB1 with specific antibodies significantly suppressed tumorous angiogenesis and alleviated gemcitabine resistance of UC. Overall, our findings demonstrated that the driven force of chemotherapy resistance and recurrence of UC was EMT-UC mediated COL4A1-ITGB1 interaction, providing a potential target for future UC treatment.

Analyzing small RNA sequences from canine stem cell-derived extracellular vesicles primed with TNF-α and IFN-γ and exploring their potential in lung repair.

Acute lung injury is an acute inflammation disorder that disrupts the lung endothelial and epithelial barriers. In this study, we investigated the extracellular vesicles (EVs) obtained via priming inflammatory cytokines such as tumor necrosis factor (TNF)-α and interferon (IFN)-γ on canine adipose mesenchymal stem cells in improving their anti-inflammatory and/or immunosuppressive potential, and/or their ability to alleviate lipopolysaccharide-induced lung injury in vitro. We also explored the correlation between epithelial-to-mesenchymal transition and the inflammatory repressive effect of primed EVs. Using small RNA-Seq, we confirmed that miR-16 and miR-502 significantly increased in EVs from TNF-α and IFN-γ-primed canine adipose mesenchymal stem cells. The pro and anti-inflammatory cytokines were analyzed in a lipopolysaccharide-induced lung injury model and we found that the EV anti-inflammatory effect improved on priming with inflammatory cytokines. EVs obtained from primed stem cells effectively suppress endothelial-to-mesenchymal transition in a lung injury model. Our results suggest a potential therapeutic approach utilizing EVs obtained from adipose mesenchymal stem cells primed with TNF-α and IFN-γ against lung inflammation and endothelial to mesenchymal transition.

A CD36-dependent non-canonical lipid metabolism program promotes immune escape and resistance to hypomethylating agent therapy in AML

Environmental lipids are essential for fueling tumor energetics, but whether these exogenous lipids transported into cancer cells facilitate immune escape remains unclear. Here, we find that CD36, a transporter for exogenous lipids, promotes acute myeloid leukemia (AML) immune evasion. We show that, separately from its established role in lipid oxidation, CD36 on AML cells senses oxidized low-density lipoprotein (OxLDL) to prime the TLR4-LYN-MYD88-nuclear factor κB (NF-κB) pathway, and exogenous palmitate transfer via CD36 further potentiates this innate immune pathway by supporting ZDHHC6-mediated MYD88 palmitoylation. Subsequently, NF-κB drives the expression of immunosuppressive genes that inhibit anti-tumor Tcell responses. Notably, high-fat-diet or hypomethylating agent decitabine treatment boosts the immunosuppressive potential of AML cells by hijacking CD36-dependent innate immune signaling, leading to a dampened therapeutic effect. This work is of translational interest because lipid restriction by US Food and Drug Administration (FDA)-approved lipid-lowering statin drugs improves the efficacy of decitabine therapy by weakening leukemic CD36-mediated immunosuppression.

Dental Pulp Stem Cells Modulate Inflammasome Pathway and Collagen Deposition of Dermal Fibroblasts.

Fibrosis is a pathological condition consisting of a delayed deposition and remodeling of the extracellular matrix (ECM) by fibroblasts. This deregulation is mostly triggered by a chronic stimulus mediated by pro-inflammatory cytokines, such as TNF-α and IL-1, which activate fibroblasts. Due to their anti-inflammatory and immunosuppressive potential, dental pulp stem cells (DPSCs) could affect fibrotic processes. This study aims to clarify if DPSCs can affect fibroblast activation and modulate collagen deposition. We set up a transwell co-culture system, where DPSCs were seeded above the monolayer of fibroblasts and stimulated with LPS or a combination of TNF-α and IL-1β and quantified a set of genes involved in inflammasome activation or ECM deposition. Cytokines-stimulated co-cultured fibroblasts, compared to unstimulated ones, showed a significant increase in the expression of IL-1β, IL-6, NAIP, AIM2, CASP1, FN1, and TGF-β genes. At the protein level, IL-1β and IL-6 release as well as FN1 were increased in stimulated, co-cultured fibroblasts. Moreover, we found a significant increase of MMP-9 production, suggesting a role of DPSCs in ECM remodeling. Our data seem to suggest a crosstalk between cultured fibroblasts and DPSCs, which seems to modulate genes involved in inflammasome activation, ECM deposition, wound healing, and fibrosis.

Tumor-associated KLRG1+ Tregs drive a dominant immunosuppressive program in Non-small Cell Lung Cancer

Abstract Killer cell lectin-like receptor G1 (KLRG1) is a co-inhibitory receptor expressed on T and NK cells. While KLRG1’s role in effector T and NK cells has been extensively documented, its impact on regulatory T cells (Tregs) remains poorly understood. This study aims to characterize and compare the immunosuppressive potential of KLRG1+ Tregs in contrast to KLRG1- Tregs and their therapeutic targeting in non-small cell lung cancer (NSCLC). CTV-labelled effector T cells were cultured with TAMs and tumor digests in the presence or absence of each Treg subpopulation for 5 days in a Treg suppression assay. For in vivo studies, T cells with either KLRG1+ or KLRG1- Tregs were adoptively transferred into lung tumor-bearing mice. Intracellular staining for GZB, IFN-γ and TNF-α was performed on the processed tumor cells. Lastly, cohorts of tumor-bearing KP mice were treated with a KLRG1-blocking antibody for 6 weeks. Our study revealed that KLRG1+ Tregs exhibit robust suppressive functions both in vitro and in vivo, contingent upon intact KLRG1 signaling. Blockade of KLRG1 in vitro and in vivo profoundly arrested tumor growth, augmented effector T cell activity, and significantly prolonged the survival of tumor-bearing mice. In conclusion, KLRG1+ Tregs drives immunosuppressive activity in the tumor microenvironment; this provides novel insights into the functional dynamics of KLRG1+ Tregs and underscores their therapeutic potential for boosting anti-tumor T cell responses in NSCLC.

Mesenchymal Stem Cells Induce an Immunosuppressive Microenvironment in Pituitary Tumors.

The tumor microenvironment (TME) includes diverse cellular components such as mesenchymal stem cells (MSCs) and immune cells, among others. MSC have been isolated from different tumors and they favor tumor cell growth; however, their role in pituitary tumors (PTs) remains unknown. Herein we report the presence of MSCs in 2 adrenocorticotropin (ACTH)-secreting PTs causing Cushing disease (MCU), 2 nonfunctioning adenomas of gonadotrope differentiation (MNF), and 2 nontumoral pituitary glands (MS). We have analyzed the transcriptomic profiles by RNA sequencing and compared MSCs in terms of their immunosuppressive effects against lymphoid T-cell and macrophage populations by means of cocultures and flow cytometry. Our transcriptomic analysis revealed molecular differences between MSCs derived from nontumoral pituitaries and MSCs derived from PTs. Two distinct subpopulations of MSC emerged: one displaying immunosuppressive properties and the other with increased proproliferative capabilities, regardless of their origin. MSCs derived from ACTH- and nonfunctioning PTs, but not those derived from nontumoral glands, significantly inhibited the proliferation of activated T cells, favored the generation of regulatory T cells, and promoted M2 macrophage polarization. Such immunosuppressive effects were correlated with an upregulation of programmed death ligand 1 and intracellular expression of macrophage colony-stimulating factor (M-CSF) and interleukin-10. Importantly, MSC derived from ACTH-PTs showed a higher immunosuppressive potential than MSC isolated from nonfunctioning tumors. This study demonstrates the presence of at least 2 MSC subpopulations in the pituitary gland and suggests that immunosuppressive effects of MSCs may have important implications in PT growth.

Discussion Abounds on the Potential Carcinogenic Risks Associated With the Use of UV Curing Lamps for Permanent Nail Polish

BackgroundControversy has recently broken out over the potential carcinogenic risk associated with exposure to UV lamps for permanent nail polish. The new LED-based polymerization devices, and their potential biological effect has not been analyzed to this date. ObjectiveTo evaluate the emission power and its potential biological effects on the skin of 2 types of UV LED and fluorescent curing lamps under normal use conditions compared to doses of sunlight exposure. Material and methodsThe emission spectrum (290nm to 450nm) of curing lamps and the Sun at noon on an average summer day in mid-latitude Spain was analyzed. The effective biological irradiance potential for erythema, non-melanoma skin cancer, DNA damage, photoimmunosuppression and permanent pigmentation was also characterized. ResultsThe high-energy UVA-visible irradiance emitted by these devices was similar to the one coming from the Sun in that spectral range while the effective biological doses were lower or similar to those also coming from the Sun. The total UV and high-energy visible dose per manicure session corresponded to that obtained from 3.5min to 6min exposures to the Sun at noon in the summer days at our latitudes. ConclusionsThe exposure times and doses received with the common use of artificial lamp nail drying correspond to sunlight exposures of 3min to 5min in the central hours of the day. This represents a very low carcinogenic potential compared to sunlight exposure, although similar regarding immunosuppressive potential. Photoprotective measures would further minimize the risks.

Abstract 6883: Investigation of tumor-immune interactions in pediatric sarcomas using single-cell multi-omics

Abstract Background: Pediatric sarcoma represents the second most common solid tumor in children. Despite advances in multimodal therapies, one-third of sarcoma patients do not survive the disease. Over the past few decades, the development of novel therapeutic strategies for sarcoma has been impeded by an insufficient understanding of the tumor microenvironment (TME). In particular, the potential of immunotherapy remains constrained by the gap of knowledge about the molecular and functional phenotypes of the immune cells in the sarcoma TME. Methods: To address this knowledge gap, we collected treatment-naïve tumor samples from 32 patients with five pediatric sarcoma subtypes. We employed a single-nuclei RNA+ATAC-Seq multi-omics assay to comprehensively characterize the transcriptomic and epigenomic heterogeneity of tumor and immune cells within the sarcoma TME. Results: Our analysis revealed that tumor-associated macrophages (TAMs) were the most abundant immune cell type in the sarcoma TME. We identified seven distinct TAM subpopulations, each exhibiting unique gene expression and chromatin accessibility patterns. Among these, TAM subsets with higher expression of SPP1 and C1QC genes displayed the strongest immunosuppressive potential. Transcriptional regulatory network (TRN) analysis identified transcription factors that were most likely to drive the phenotypes of SPP1+ and C1QC+ TAMs, including ELF2, JUND and RUNX1. Through cell-cell communication analysis, we discovered that SPP1+ TAMs interact with T cells via SPP1-CD44 signaling, while C1QC+ TAMs interact with NK cells through HLA-E-KLRC1 signaling, suggesting the potential involvement of these signaling pathways in TAM-mediated suppression of these cytotoxic lymphocytes. We prioritized ligand-receptor gene pairs, such as SEMA3D-NRP1 and LTBP3-ITGB5, which likely mediate the interaction between malignant sarcoma cells and SPP1+/C1QC+ TAMs based on their dominance across sarcoma subtypes and association with poorer clinical outcomes. On the other hand, our analysis revealed that sarcoma subtype-specific interactions between TAMs and malignant cells are common, highlighting the heterogeneity of signaling events across sarcoma subtypes. Conclusion and Significance: Our study presents a comprehensive single-cell multi-omics characterization of pediatric sarcomas and sheds light on its tumor microenvironment. By identifying unique markers for immunosuppressive TAM subpopulations and elucidating intercellular interactions promoting tumor development, this study proposes potential therapeutic targets for sarcoma treatment based on the role of TAMs in sarcoma TME. Citation Format: Zhan Zhang, Kyung Jin Ahn, Changya Chen, Rumeysa Biyik Sit, Hesham Mohei, Brian Lockhart, Malay Haldar, Kathrin Bernt, Vinodh Pillai, Kai Tan. Investigation of tumor-immune interactions in pediatric sarcomas using single-cell multi-omics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6883.

Abstract 5355: A novel subset of Treg-like MDSCs expressing LAG-3 found in advanced gastric cancer

Abstract The development and progression of cancers are frequently promoted by immunosuppressive cells, such as Treg and myeloid-derived suppressor cells (MDSCs) mediated by various immune checkpoint molecules. Therefore, MDSCs are potential diagnostic and therapeutic targets in cancer. However, the definitive cell surface markers for defining MDSC and the subset that correlates with cancer progression are not clear. In our previous studies, there was no difference in the amount of total granulocyte MDSCs (G-MDSCs) between early and advanced gastric cancer. We inferred that there is a novel subset of G-MDSCs involved in cancer progression rather than the previous marker-based classification. The purpose of this study is to analyze MDSCs in gastric cancer patients at different stages of progression and to identify subsets of G-MDSCs that are involved in cancer progression. As a result, we identified a subset of novel G-MDSCs that correlate with cancer progression by expressing LAG-3. LAG-3 is a molecule that is expressed in Tregs and causes strong immunosuppression, suggesting that it is involved in the immunosuppressive potential of MDSCs. Citation Format: Takumi Iwasawa, Suguru Yamauchi, Tetsu Fukunaga, Hajime Orita, Tomoaki Ito, Kato Kazunori. A novel subset of Treg-like MDSCs expressing LAG-3 found in advanced gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5355.

Impacts of priming on distinct immunosuppressive mechanisms of mesenchymal stromal cells under translationally relevant conditions

BackgroundThe multimodal properties of mesenchymal stromal cells (MSCs), particularly their ability to modulate immune responses is of high interest in translational research. Pro-inflammatory, hypoxic, and 3D culture priming are promising and often used strategies to improve the immunosuppressive potency of MSCs, but the underlying mechanisms are not well understood. Therefore, the aims of this study were (i) to compare the effects of pro-inflammatory, hypoxic, and 3D culture priming on the in vitro immunosuppressive potential of MSCs, (ii) to assess if immunosuppressive priming effects are temporally preserved under standard and translationally relevant culture conditions, and (iii) to investigate if the three priming strategies engage the same immunosuppressive mechanisms.MethodsFunctional in vitro T cell suppressive potency measurements were conducted to assess the impact of pro-inflammatory, hypoxic, and 3D culture priming on the immunosuppressive potential of human bone marrow-derived MSCs. Primed MSCs were either cultured under standard cell culture conditions or translationally relevant culture conditions, and their transcriptomic adaptations were monitored over time. Next-generation sequencing was performed to assess if different priming strategies activate distinct immunosuppressive mechanisms.Results(i) Pro-inflammatory, hypoxic, and 3D culture priming induced profound transcriptomic changes in MSCs resulting in a significantly enhanced T cell suppressive potential of pro-inflammatory and 3D culture primed MSCs. (ii) Priming effects rapidly faded under standard cell culture conditions but were partially preserved under translationally relevant conditions. Interestingly, continuous 3D culture priming of MSCs maintained the immunosuppressive potency of MSCs. (iii) Next-generation sequencing revealed that priming strategy-specific differentially expressed genes are involved in the T cell suppressive capacity of MSCs, indicating that different priming strategies engage distinct immunosuppressive mechanisms.ConclusionPriming can be a useful approach to improve the immunosuppressive potency of MSCs. However, future studies involving primed MSCs should carefully consider the significant impact of translationally relevant conditions on the preservation of priming effects. Continuous 3D culture could act as a functionalized formulation, supporting the administration of MSC spheroids for a sustainably improved immunosuppressive potency.

Controversias sobre los riesgos procarcinogénicos asociados al uso de lámparas ultravioleta polimerizadoras para el esmaltado permanente de uñas

BackgroundControversy has recently broken out over the potential carcinogenic risk associated with exposure to UV lamps for permanent nail polish. The new LED-based polymerization devices, and their potential biological effect has not been analyzed to this date. ObjectiveTo evaluate the emission power and its potential biological effects on the skin of 2 types of UV LED and fluorescent curing lamps under normal use conditions compared to doses of sunlight exposure. Material and methodsThe emission spectrum (290nm to 450nm) of curing lamps and the Sun at noon on an average summer day in mid-latitude Spain was analyzed. The effective biological irradiance potential for erythema, non-melanoma skin cancer, DNA damage, photoimmunosuppression and permanent pigmentation was also characterized. ResultsThe high-energy UVA-visible irradiance emitted by these devices was similar to the one coming from the Sun in that spectral range while the effective biological doses were lower or similar to those also coming from the Sun. The total UV and high-energy visible dose per manicure session corresponded to that obtained from 3.5min to 6min exposures to the Sun at noon in the summer days at our latitudes. ConclusionsThe exposure times and doses received with the common use of artificial lamp nail drying correspond to sunlight exposures of 3min to 5min in the central hours of the day. This represents a very low carcinogenic potential compared to sunlight exposure, although similar regarding immunosuppressive potential. Photoprotective measures would further minimize the risks.

IFN-γ-Licensed Mesenchymal Stem Cells Are More Susceptible to Death when Exposed to Quorum-Sensing Signal Molecule OdDHL and Less Effective in Inhibiting the Growth of Pseudomonas aeruginosa.

Currently, a series of licensing strategies has been investigated to enhance the functional properties of mesenchymal stem cells (MSCs). Licensing with IFN-γ is one of the most investigated strategies for enhancing the immunosuppressive potential of such cells. However, it is not yet known whether this licensing strategy could interfere with the ability of MSCs to control bacterial growth, which may be relevant considering their clinical potential. In this study, we compared the antimicrobial potential of IFN-γ-licensed and unlicensed MSCs by exposing them to Pseudomonas aeruginosa and its quorum-sensing inducer molecule OdDHL. Our data show that-when challenged with OdDHL-IFN-γ-licensed and unlicensed MSCs present increased levels of the antimicrobial HAMP transcript, but that only IFN-γ-licensed MSCs undergo modulation of CASP1 and BCL2, entering apoptosis. Furthermore, we demonstrate that only IFN-γ-licensed MSCs show modulation in genes involved in apoptosis and tend to undergo cell death when cultured with P. aeruginosa. As a consequence, IFN-γ-licensed MSCs showed lower capacity to control bacterial growth, compared to unlicensed MSCs. Taken together, our observations reveal an increased susceptibility to apoptosis of IFN-γ-licensed MSCs, which compromises their potential to control the bacterial growth in vitro. These findings are relevant to the field of cell therapy, considering the potential applicability of MSCs.

Coinfection with Leishmania infantum and Toxoplasma gondii in Domestic Cats from a Region with a High Prevalence of Feline Immunodeficiency Virus.

The aim of this study was to investigate the coinfection of feline retroviruses (feline immunodeficiency virus-FIV, and the feline leukemia virus-FeLV) with Leishmania infantum and Toxoplasma gondii and the factors associated with these pathogens in domestic cats from Mossoró, a city endemic for canine and human leishmaniasis situated in the semiarid region of Northeast Brazil. Blood samples from 120 cats were collected, and an epidemiological questionnaire was applied to investigate the risk factors associated with the infections. Retroviruses, L. infantum, and T. gondii infections were assessed using a point-of-care ELISA and quantitative PCR (qPCR), indirect fluorescent antibody test (IFAT) and qPCR, and IFAT, respectively. The overall seroprevalences observed were 35% (95% CI = 27.0-43.8%) for FIV, 0.8% (95% CI = 0.1-4.5%) for FeLV, 25.8% (95% CI = 18.8-34.3%) for T. gondii, and 4.2% (95% CI = 1.7-9.3%) for L. infantum. Coinfection with FIV and L. infantum was observed in 2.5% (3/120) of the assessed cats, while 12.5% (15/120) were coinfected with FIV and T. gondii. No significant association was found among the investigated agents (p > 0.05). The factors associated with FIV infection in the multivariable analysis were male sex and age above 78 months. The findings of this study demonstrated a high rate of FIV infection in cats from the Brazilian semiarid region and the exposure of these animals to zoonotic and opportunistic agents. Due to the immunosuppressive potential of FIV, cats infected with this retrovirus should be screened for coinfections with L. infantum and T. gondii, and preventative measures should be adopted.