High-resolution Flow Cytometry Research Articles

Cancer-associated foam cells hamper protective T cell immunity and favor tumor progression in human colon carcinogenesis

BackgroundColorectal cancer (CRC) remains a significant healthcare burden worldwide, characterized by a complex interplay between obesity and chronic inflammation. While the relationship between CRC, obesity and altered lipid metabolism is...

The G Protein-Coupled Receptor GPR56 Is an Inhibitory Checkpoint for NK Cell Migration.

G protein-coupled receptors (GPCRs) represent the largest family of surface receptors and are responsible for key physiological functions, including cell growth, neurotransmission, hormone release, and cell migration. The GPCR 56 (GPR56), encoded by ADGRG1, is an adhesion GPCR found on diverse cell types, including neural progenitor cells, melanoma cells, and lymphocytes, such as effector memory T cells, γδ T cells, and NK cells. Using RNA-sequencing and high-resolution flow cytometry, we found that GPR56 mRNA and protein expression increased with NK cell differentiation, reaching its peak in adaptive NK cells. Small interfering RNA silencing of GPR56 led to increased spontaneous and chemokine-induced migration, suggesting that GPR56 functions as an upstream checkpoint for migration of highly differentiated NK cells. Increased NK cell migration could also be induced by agonistic stimulation of GPR56 leading to rapid internalization and deactivation of the receptor. Mechanistically, GPR56 ligation and downregulation were associated with transcriptional coactivator with PDZ-binding motif translocation to the nucleus and increased actin polymerization. Together, these data provide insights into the role of GPR56 in the migratory behavior of human NK cell subsets and may open possibilities to improve NK cell infiltration into cancer tissues by releasing a migratory checkpoint.

EGFR Mutation and TKI Treatment Promote Secretion of Small Extracellular Vesicle PD-L1 and Contribute to Immunosuppression in NSCLC.

In Asian populations with non-small-cell lung cancer (NSCLC), EGFR mutations are highly prevalent, occurring in roughly half of these patients. Studies have revealed that individuals with EGFR mutation typically fare worse with immunotherapy. In patients who received EGFR tyrosine kinase inhibitor (TKI) treatment followed by anti-PD-1 therapy, poor results were observed. The underlying mechanism remains unclear. We used high-resolution flow cytometry and ELISA to detect the circulating level of small extracellular vesicle (sEV) PD-L1 in NSCLC individuals with EGFR mutations before and after receiving TKIs. The secretion amount of sEV PD-L1 of lung cancer cell lines with EGFR mutations under TKI treatment or not were detected using high-resolution flow cytometry and Western blotting. The results revealed that patients harboring EGFR mutations exhibit increased levels of sEV PD-L1 in circulation, which inversely correlated with the presence of CD8+ T cells in tumor tissues. Furthermore, tumor cells carrying EGFR mutations secrete a higher quantity of PD-L1-positive sEVs. TKI treatment appeared to amplify the levels of PD-L1-positive sEVs in the bloodstream. Mutation-induced and TKI-induced sEVs substantially impaired the functionality of CD8+ T cells. Importantly, our findings indicated that EGFR mutations and TKI therapies promote secretion of PD-L1-positive sEVs via distinct molecular mechanisms, namely the HRS and ALIX pathways, respectively. In conclusion, the increased secretion of PD-L1-positive sEVs, prompted by genetic alterations and TKI administration, may contribute to the limited efficacy of immunotherapy observed in EGFR-mutant patients and patients who have received TKI treatment.

Interleukin-6 receptor blockade with tocilizumab to reduce immune-related toxicity with ipilimumab and nivolumab in metastatic melanoma.

9538 Background: Interleukin-6(IL-6) blockade has reversed steroid-refractory immune-related toxicity in patients receiving immune checkpoint blockade (ICB). IL-6 and its downstream acute phase reactants are also associated with short survival and therapeutic resistance in patients receiving single agent or combination ICB. We undertook a phase II trial of IPI, NIVO and the IL-6 receptor blocking antibody tocilizumab (TOCI) in unresectable melanoma. Methods: In a phase II, Simon-design two-stage trial, 70 patients with untreated metastatic melanoma received IPI at 1 mg/kg and NIVO at 3 mg/kg for 4 induction doses to week 12, and TOCI at 4 mg/kg every 6 weeks up to week 24. Maintenance NIVO was administered at 240 mg intravenously (IV) from weeks 12 to 24, then at a dose of 480 mg IV every 4 weeks for up to 2 years of treatment. To proceed past the first stage of 18 patients, 12/18 RECIST responses or more and/or a grade 3-5 treatment related immune-related adverse event (irAE) rate of ≤5/18 were required. Those criteria were both fulfilled, and in the second stage 49 patients were treated, with 3 additional patients accrued. Serum and peripheral blood samples were collected for biomarker assays at baseline and week 7. Results: There were 40/70 RECIST responders with a 57% best overall response rate (BORR), (exact 95% confidence interval (CI) of 44-68%) of partial response (PR) or complete response (CR); 6 patients had stable disease (SD), 24 with progression, at a median of 2.4 years of follow-up. A total of 46 patients had clinical benefit (CR+PR+SD) = 65% (exact 95% CI 37-81%). Median progression-free survival was 13 months. The expected BORR was 47% in the randomized Checkmate-511 trial at the same doses of IPI/NIVO. There have been 16 cases of grades 3-4 irAE including 3 episodes of colitis for a total of 16/71 patients eligible for toxicity = 22% (exact 95% CI: 12-31%), all grade 3/4; the expected rate of grades 3-5 TRAEs was 34% per Checkmate-511. The rate of irAE leading to discontinuation was 14%; it was 25% for CheckMate 511. Twenty-one deaths (30%) occurred, all due to progression. All grade 3-4 irAES were reversible and no grade 5 toxicity was seen. Osteopontin+IL6+CD45RAnegclassical monocytes were associated with response, and higher levels of naive CD8 T cells were associated with progression. CD16+CD56+CD57+ mature natural killer cells were significantly lower in patients with grade 3-4 immune-related toxicity. Conclusions: Prophylactic TOCI resulted in a low rate of grade 3-4 irAEs by week 24 in patients with stage IV melanoma receiving induction IPI 1 mg/kg and NIVO 3 mg/kg while maintaining a favorable overall response rate and survival. Novel biomarkers of response and toxicity including NK cells and monocytes as well as naïve and effector memory CD8 T cells were defined by high-resolution flow cytometry. Additional correlative data will be presented. Clinical trial information: NCT03999749 .

#1219 Extracellular vesicles from patients with AMR-induced reprogramming of human podocytes into senescent cells: role of SGLT2i

Abstract Background and Aims Extracellular vesicles (EVs) are organelles released by different cells that deliver biological information into the extracellular space and contribute to several diseases. However, their role in patients with antibody-mediated allograft rejection (AMR) remains uncertain. Our aim was to test the influence of plasma-derived EVs on human conditional immortalized podocytes (PODO) by investigating the possible role of dapagliflozin (Dapa) as a pharmacological agent. Methods Twenty-eight Rtx patients were included in the study, 14 with AMR, and 14 control TX patients (RTX). (CTRL). Plasma-derived Evs were used to stimulate PODO for 24 h, followed by exposure to 100 nM Dapa for 24 h. Differential ultracentrifugation at 110,000 g was applied, followed by counting with Nanosight and characterization by high-resolution flow cytometry according to the MISEV2018 criteria. PKH26 dye was used for the EVs-PODO incorporation study using Z-stack microscopy image acquisition. Total RNA and protein were extracted for gene expression and protein analysis, and the cells were fixed for immunostaining evaluation. Results We first found that upon activation with EV, PODO incorporated Es and shared them between cells; moreover, AMR-EVs led to an increased expression of tetraspanin marker of cell activation CD9 (p = 0.028) compared with CTRL. Importantly, the incubation of PODO with RTX-EVs induced a senescence-associated secretory phenotype (TNF alpha p = 0.0006, MCP1 p = 0.014); with cytoskeletal dysregulation and increase in gene expression and proteins involved in the epithelial to mesenchymal transition such as VIM (p = 0.026), senescence P21 (p = 0.04), inflammation CD44 (p = 0.034) with downregulation of Klotho (p = 0.002). Interestingly, incubation with Dapagliflozin significantly counteract PODO activation with reduction in P21 expression (p = 0.039) and an increase in Klotho (p = 0.047) abrogating inflammaging. Conclusions Our findings demonstrate that plasma EVs of AMR induced cellular senescence in PODO, reprogramming cellular processes such as cytoskeleton shape and composition, secretion of inflammatory cytokines, and decrease of the nephroprotective protein Klotho. This pathogenic process can be efficiently counteracted by SGLT2i.

Chikungunya-virus-specific CD4+ T cells are associated with chronic chikungunya viral arthritic disease in humans

Abstract Chikungunya virus (CHIKV) is a mosquito-borne Alphavirus that causes recurrent outbreaks in tropical and subtropical regions of the world. In the first 2-7 days of infection, most individuals experience high fever, skin rash and joint pain and swelling. However, about 30-60% of the infected individuals, primarily middle-age females, develop debilitating chronic arthritis-like symptoms such as joint pain, muscle aches and edema. Despite ongoing treatment and vaccine development efforts, the immune responses to CHIKV in humans remain largely understudied. In this study, we tested peripheral blood mononuclear cells (PBMCs) collected from a cohort of 39 individuals diagnosed with CHIKV disease during the 2014-2015 epidemic in Colombia against pools of overlapping sequentially spanning the entire CHIKV genome. Using high-resolution spectral flow cytometry, we detected robust CHIKV-specific CD4+ T cell responses, but not CD8+ T cell responses in the periphery. Patients experiencing chronic symptoms displayed a significantly higher abundance of CHIKV-specific memory CD4+ T cells, compared to their recovered counterparts. Furthermore, these CD4+ T cells displayed a significantly lower Th1 phenotype but were enriched in the Th17 phenotype, with the predominant production of TNFɑ. Overall, our work demonstrates that CD4+ T cells play a pivotal role in the pathogenesis of CHIKV and provides insight into possible therapeutic options.

Immune system-related plasma extracellular vesicles in healthy aging.

To identify age-related plasma extracellular vehicle (EVs) phenotypes in healthy adults. EV proteomics by high-resolution mass spectrometry to evaluate EV protein stability and discover age-associated EV proteins (n=4 with 4 serial freeze-thaws each); validation by high-resolution flow cytometry and EV cytokine quantification by multiplex ELISA (n=28 healthy donors, aged 18-83 years); quantification of WI-38 fibroblast cell proliferation response to co-culture with PKH67-labeled young and old plasma EVs. The EV samples from these plasma specimens were previously characterized for bilayer structure, intra-vesicle mitochondria and cytokines, and hematopoietic cell-related surface markers. Compared with matched exo-EVs (EV-depleted supernatants), endo-EVs (EV-associated) had higher mean TNF-α and IL-27, lower mean IL-6, IL-11, IFN-γ, and IL-17A/F, and similar mean IL-1β, IL-21, and IL-22 concentrations. Some endo-EV and exo-EV cytokine concentrations were correlated, including TNF-α, IL-27, IL-6, IL-1β, and IFN-γ, but not IL-11, IL-17A/F, IL-21 or IL-22. Endo-EV IFN-γ and exo-EV IL-17A/F and IL-21 declined with age. By proteomics and confirmed by flow cytometry, we identified age-associated decline of fibrinogen (FGA, FGB and FGG) in EVs. Age-related EV proteins indicated predominant origins in the liver and innate immune system. WI-38 cells (>95%) internalized similar amounts of young and old plasma EVs, but cells that internalized PKH67-EVs, particularly young EVs, underwent significantly greater cell proliferation. Endo-EV and exo-EV cytokines function as different biomarkers. The observed healthy aging EV phenotype reflected a downregulation of EV fibrinogen subpopulations consistent with the absence of a pro-coagulant and pro-inflammatory condition common with age-related disease.

Human placenta releases extracellular vesicles carrying corticotrophin releasing hormone mRNA into the maternal blood

The human placenta releases diverse extracellular vesicles (EVs), including microvesicles (100–1000 nm) and exosomes (30–150 nm), into the maternal blood for feto-maternal communication. Exosomes and microvesicles contribute to normal pregnancy physiology and major pregnancy pathologies. Differences in miRNA expressions and protein content in placental exosomes have been reported in complicated pregnancies. During human pregnancy, Corticotropin-Releasing Hormone (CRH) is produced and released by the placenta into the maternal blood. CRH is involved in regulating gestational length and the initiation of labour. CRH mRNA levels in the maternal plasma rise with gestation. High levels of CRH mRNA are reported to be associated with preeclamptic and preterm pregnancies. However, the underlying mechanism of placental CRH mRNA secretion remains to be elucidated. We hypothesise that the placenta releases CRH mRNA packaged within extracellular vesicles (EVs) into the maternal blood. In this study, placental EVs (microvesicles and exosomes) were isolated from human term healthy placentas via villus washes and from explant culture media by differential centrifugation and purified by density gradient ultracentrifugation using a continuous sucrose gradient (0.25–2.5 M). Western blotting using placenta- and exosome-specific markers and electron microscopy confirmed exosomes and microvesicles in the placental wash and explant media samples. Real-time quantitative RT-PCR data detected CRH mRNA in placenta-derived EVs from placental washes and explants. We also sorted placenta-secreted EVs in maternal plasma samples (≥37 weeks) by high-resolution flow cytometry using a fluorescent-labelled PLAP antibody. CRH mRNA was demonstrated in placental EVs obtained from maternal blood plasma. We therefore show that human placental EVs carry CRH mRNA into the maternal blood. Our study implies that measuring CRH mRNA in placental EVs in the maternal plasma could beused for monitoring pregnancy.

GABARAPL1 is essential in extracellular vesicle cargo loading and metastasis development

Background and purposeHypoxia is a common feature of tumours, associated with poor prognosis due to increased resistance to radio- and chemotherapy and enhanced metastasis development. Previously we demonstrated that GABARAPL1 is required for the secretion of extracellular vesicles (EV) with pro-angiogenic properties during hypoxia. Here, we explored the role of GABARAPL1+ EV in the metastatic cascade. Materials and methodsGABARAPL1 deficient or control MDA-MB-231 cells were injected in murine mammary fat pads. Lungs were dissected and analysed for human cytokeratin 18. EV from control and GABARAPL1 deficient cells exposed to normoxia (21% O2) or hypoxia (O2 < 0.02%) were isolated and analysed by immunoblot, nanoparticle tracking analysis, high resolution flow cytometry, mass spectrometry and next-generation sequencing. Cellular migration and invasion were analysed using scratch assays and transwell-invasion assays, respectively. ResultsThe number of pulmonary metastases derived from GABARAPL1 deficient tumours decreased by 84%. GABARAPL1 deficient cells migrate slower but display a comparable invasive capacity. Both normoxic and hypoxic EV contain proteins and miRNAs associated with metastasis development and, in line, increase cancer cell invasiveness. Although GABARAPL1 deficiency alters EV content, it does not alter the EV-induced increase in cancer cell invasiveness. ConclusionGABARAPL1 is essential for metastasis development. This is unrelated to changes in migration and invasion and suggests that GABARAPL1 or GABARAPL1+ EV are essential in other processes related to the metastatic cascade.

Isolated Extramedulary Relapse in T-Acute Lymphoblastic Leukemia

Isolated extramedullary acute lymphoblastic leukemia is a rare phenomenon. This event is more common in acute myeloid leukemia as myeloid sarcoma. This terminology is near the lymphoblastic lymphoma. Isolated extramedullary presentations hasn’t bone marrow involvement morphologically .Submicroscopic bone marrow involvement confirmed by a high-resolution flowcytometry detection method.

Identifying cancer-associated leukocyte profiles using high-resolution flow cytometry screening and machine learning.

Machine learning (ML) is a valuable tool with the potential to aid clinical decision making. Adoption of ML to this end requires data that reliably correlates with the clinical outcome of interest; the advantage of ML is that it can model these correlations from complex multiparameter data sets that can be difficult to interpret conventionally. While currently available clinical data can be used in ML for this purpose, there exists the potential to discover new "biomarkers" that will enhance the effectiveness of ML in clinical decision making. Since the interaction of the immune system and cancer is a hallmark of tumor establishment and progression, one potential area for cancer biomarker discovery is through the investigation of cancer-related immune cell signatures. Hence, we hypothesize that blood immune cell signatures can act as a biomarker for cancer progression. To probe this, we have developed and tested a multiparameter cell-surface marker screening pipeline, using flow cytometry to obtain high-resolution systemic leukocyte population profiles that correlate with detection and characterization of several cancers in murine syngeneic tumor models. We discovered a signature of several blood leukocyte subsets, the most notable of which were monocyte subsets, that could be used to train CATboost ML models to predict the presence and type of cancer present in the animals. Our findings highlight the potential utility of a screening approach to identify robust leukocyte biomarkers for cancer detection and characterization. This pipeline can easily be adapted to screen for cancer specific leukocyte markers from the blood of cancer patient.

Polymorphic KIR3DL3 expression modulates tissue-resident and innate-like T cells.

Most human killer cell immunoglobulin-like receptors (KIR) are expressed by natural killer (NK) cells and recognize HLA class I molecules as ligands. KIR3DL3 is a conserved but polymorphic inhibitory KIR recognizing a B7 family ligand, HHLA2, and is implicated for immune checkpoint targeting. The expression profile and biological function of KIR3DL3 have been somewhat elusive, so we searched extensively for KIR3DL3 transcripts, revealing highly enriched expression in γδ and CD8+ T cells rather than NK cells. These KIR3DL3-expressing cells are rare in the blood and thymus but more common in the lungs and digestive tract. High-resolution flow cytometry and single-cell transcriptomics showed that peripheral blood KIR3DL3+ T cells have an activated transitional memory phenotype and are hypofunctional. The T cell receptor (TCR) usage is biased toward genes from early rearranged TCR-α variable segments or Vδ1 chains. In addition, we show that TCR-mediated stimulation can be inhibited through KIR3DL3 ligation. Whereas we detected no impact of KIR3DL3 polymorphism on ligand binding, variants in the proximal promoter and at residue 86 can reduce expression. Together, we demonstrate that KIR3DL3 is up-regulated alongside unconventional T cell stimulation and that individuals may vary in their ability to express KIR3DL3. These results have implications for the personalized targeting of KIR3DL3/HHLA2 checkpoint inhibition.

BIO15: Inhibition of Leukocytes Decreases Thrombin Generation in a In Vitro ECMO model

Background: Despite systemic anti-coagulation, blood exposure to extracorporeal membrane oxygenation circuits (ECMO) generates excess thrombin, often resulting in thrombus formation, device failure, and life-threatening thromboembolism. Activated leukocytes and platelets promote ECMO thrombosis under controlled static and flow conditions. Previous studies document that phosphodiesterase type 4 inhibitor (PDE4) can selectively inhibit the pro-thrombotic function of leukocytes. Our hypothesis is that roflumilast (PDE4 inhibitor) decreases thrombin generation in an in vitro ECMO model using human blood. Methods: Simulated neonatal roller pump with a KIDS D100 oxygenator circulated human whole blood at a nominal flow rate (0.5 L/min) for six hours or until clot formation caused device failure. Samples were collected hourly from the ECMO model that received heparin alone or heparin plus roflumilast, a PDE4 inhibitor. Expression of pro-thrombotic proteins on leukocytes and extracellular vesicles (EV) was measured with high-resolution flow cytometry. A calibrated automated thrombogram without a trigger measured differences in time to thrombin and peak thrombin generation. Results: The addition of roflumilast to heparin sustained patency in 75% of tested circuits (3/4) after six hours, compared to 28% of circuits treated with heparin alone (2/7). Roflumilast decreased extracellular leukocytes expressing tissue factor. Roflumilast plus heparin prolonged time to thrombin generation at 13.9 minutes, compared to heparin alone at 6.8 minutes at the 3-hour time point (p<0.04). The addition of roflumilast significantly reduced peak thrombin generation compared to heparin alone (69 vs. 207 nm, p<0.02). Conclusions: Inhibition of leukocytes may be an effective adjunct to systematic anti-coagulation in extracorporeal life support.

Determination of genome size variation among varieties of Ilex cornuta (Aquifoliaceae) by fow cytometry

Ilex cornuta Lindl. &amp; Paxton is a commercially important horticultural species worldwide, and extensive cultivation and hybridization have produced many varieties. Despite the considerable breeding, selection, widespread cultivation and domestication, which may have a significant role in the composition of genomes, there are no other previous reports of intraspecific genome size variation in the different cultivars or hybrids of this species. In the present work, genome size of 12 varieties of I. cornuta was assessed and analyzed through high-resolution flow cytometry (FCM). Nuclear DNA was analyzed using nuclei isolated from young leaves, which used propidium iodide (PI) staining, with rice (Oryza sativa cv. Nipponbare) as internal reference. As a result, statistically significant differences in genome size were detected among all diploid I. cornuta varieties considered. The estimated genome size (2C value) of I. cornuta varieties ranged from 1.47 to 1.80 pg, with 1.22-fold variation and an average size of 1.65 pg. The domestication and interspecific hybridization induced variation of genome size in I. cornuta, and the genome size of hybrids exhibited a wider range of variation compared with that of cultivars. In summary, flow cytometry is a useful tool to analyze the genome size of I. cornuta. The first report of the genome sizes of varieties of this species would provide useful data for further research on I. cornuta, and enrich the C value database of Ilex L. What’s more, our findings could be the foundation in the future of I. cornuta genome sequencing and breeding programs.

PD17-09 CD70-POSITIVE EXTRACELLULAR VESICLES FOR DETECTION OF CLEAR-CELL RENAL CELL CARCINOMA

You have accessJournal of UrologyCME1 Apr 2023PD17-09 CD70-POSITIVE EXTRACELLULAR VESICLES FOR DETECTION OF CLEAR-CELL RENAL CELL CARCINOMA Rodrigo R. Pessoa, Reza Nabavizadeh, Ali Arafa, Roxane Lavoie, Yohan Kim, Liguo Wang, Jeanette Eckel-Passow, Bradley C. Leibovich, and Fabrice Lucien Rodrigo R. PessoaRodrigo R. Pessoa More articles by this author , Reza NabavizadehReza Nabavizadeh More articles by this author , Ali ArafaAli Arafa More articles by this author , Roxane LavoieRoxane Lavoie More articles by this author , Yohan KimYohan Kim More articles by this author , Liguo WangLiguo Wang More articles by this author , Jeanette Eckel-PassowJeanette Eckel-Passow More articles by this author , Bradley C. LeibovichBradley C. Leibovich More articles by this author , and Fabrice LucienFabrice Lucien More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003272.09AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: One third of patients treated for localized clear-cell renal cell carcinoma (ccRCC) will eventually develop recurrent disease after surgery. Identification of patients who may benefit from intensification of care with adjuvant therapy is an important unmet need. Tumor-derived extracellular vesicles (EVs), microscopic particles released by tumor cells, have emerged as a potential biomarker in other malignancies but have not been studied in kidney cancer. Herein, we sought to characterize tumor specific EVs levels among patients undergoing radical nephrectomy for ccRCC. METHODS: We employed in silico multi-omic analysis of ccRCC tumors using TCGA KIRC (N=537 patients), CPTAC (N= 103 patients) and GTEx (N= 948 donors) to identify CD70, an integral membrane protein, as the top marker candidate for ccRCC-derived EVs. Expression of CD70+ in ccRCC-derived EVs was confirmed using freshly isolated tumor specimens. Blood levels of circulating CD70+-EVs were measured using high resolution flow cytometry in a cohort of age-matched healthy donors (HD) (N=15) and ccRCC patients (N=29) treated with radical nephrectomy. EVs levels between HD and RCC patients were compared using ANOVA test. Association between patient characteristics and EVs levels was analyzed using Pearson’s correlation and Fisher’s exact test. RESULTS: Blood levels of CD70+-EVs were significantly elevated in patients with pT1-T2 (median: 4.3×106 per mL, p<0.01) and pT3-T4 (median: 6.0×106, p<0.001) ccRCC compared with HD (median: 0.4×106, Figure 1A). High CD70+-EVs levels were associated with pT3-T4 stage (Figure 1B, p<0.0001).There was a strong positive correlation between CD70+-EVs at diagnosis and tumor size (Pearson r=0.76, p<0.0001, Figure 1C). Radical nephrectomy was associated with reduction in CD70+-EVs levels in 83.8% of patients (Figure 1D, p=0.0076). CONCLUSIONS: Patients with ccRCC, in particular those with larger and more advanced stage tumors, have high levels of circulating CD70+-EVs, which decreases significantly after surgery. CD70+-EVs levels are a marker of tumor burden in ccRCC and could be further explored as a biomarker for risk-stratification and selection of patients for additional treatment after radical nephrectomy for ccRCC. Source of Funding: Eagles 5th District Cancer Telethon - Cancer Research Fund (FL) © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e499 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Rodrigo R. Pessoa More articles by this author Reza Nabavizadeh More articles by this author Ali Arafa More articles by this author Roxane Lavoie More articles by this author Yohan Kim More articles by this author Liguo Wang More articles by this author Jeanette Eckel-Passow More articles by this author Bradley C. Leibovich More articles by this author Fabrice Lucien More articles by this author Expand All Advertisement PDF downloadLoading ...

OxLDL sensitizes platelets for increased formation of extracellular vesicles capable of finetuning macrophage gene expression

Platelet extracellular vesicles (PEVs) generated upon platelet activation may play a role in inflammatory pathologies such as atherosclerosis. Oxidized low-density lipoprotein (oxLDL), a well-known contributor to atherogenesis, activates platelets and presensitizes them for activation by other agonists. We studied the effect of oxLDL on the secretion, composition, and inflammatory functions of PEVs using contemporary EV analytics. Platelets were activated by co-stimulation with thrombin (T) and collagen (C) ± oxLDL and characterized by high-resolution flow cytometry, nanoparticle tracking analysis, proximity extension assay, western blot, and electron microscopy. The effect of PEVs on macrophage differentiation and functionality was examined by analyzing macrophage surface markers, cytokine secretion, and transcriptome. OxLDL upregulated TC-induced formation of CD61+, P-selectin+ and phosphatidylserine+ PEVs. Blocking the scavenger receptor CD36 significantly suppressed the oxLDL+TC-induced PEV formation, and HDL caused a slight but detectable suppression. The inflammatory protein cargo differed between the PEVs from stimulated and unstimulated platelets. Both oxLDL+TC- and TC-induced PEVs enhanced macrophage HLA-DR and CD86 expression and decreased CD11c expression as well as secretion of several cytokines. Pathways related to cell cycle and regulation of gene expression, and immune system signaling were overrepresented in the differentially expressed genes between TC PEV -treated vs. control macrophages and oxLDL+TC PEV -treated vs. control macrophages, respectively. In conclusion, we speculate that oxLDL and activated platelets contribute to proatherogenic processes by increasing the number of PEVs that provide an adhesive and procoagulant surface, contain inflammatory mediators, and subtly finetune the macrophage gene expression.

Thyroid cells from normal and autoimmune thyroid glands suppress T lymphocytes proliferation upon contact revealing a new regulatory inhibitory type of interaction independent of PD1/PDL1

Immune Checkpoint Receptors include a number of inhibitory receptors that limit tissue damage during immune responses; blocking PD-1/PD-L1 checkpoint receptor axis led to a paradigm shift in cancer immunotherapy but also to autoimmune adverse effects, prominently thyroid autoimmunity. Although PD-L1 is known to be expressed on thyroid follicular cells (TFCs) of autoimmune glands the role on PD-1/PD-L1 in the interaction between T cells and thyroid cells in the tissue has not been investigated. Here we report that autologous primary TFCs, but not transformed TFCs, inhibit CD4 and CD8 T cell proliferation but no cytokine production. This effect is not, however, mediated by PD-1/PD-L1 nor locally produced cytokines. Beta galactosidase analysis excluded culture-induced senescence as an explanation. High resolution flow cytometry demonstrated that autologous TFC/T cells co-culture induced the expansion of several clusters of double negative (DN) T cells characterized by high expression of activation markers and negative immune checkpoints. Single cell transcriptomic profiling demonstrated that dissociated TFC express numerous candidate molecules for mediating this suppressive activity, including CD40, E-Cadherin and TIGIT ligands. These ligands directly or through the generation of a suppressor population of DN T cells, and not the PD-1/PD-L1 axis, are most likely the responsible of TFC immunosuppressive activity. These results contribute to reveal the complex network of inhibitory mechanism that operate at the tissue level to restrain autoimmunity but also point to pathways, other that PD-1/PD-L1, that can contribute to tumor evasion.

Human Nanoplatelets as Living Vehicles for Tumor-Targeted Endocytosis In Vitro and Imaging In Vivo

Recent studies have shown human platelets can access the tumor microenvironment by passive diffusion across capillaries or via activated immune cells. In a previous study, we exploited this affinity of platelets for tumor cells as part of a new approach to target tumors with modified platelets. Therefore, the engineering of human nanoplatelets as living vehicles for in vivo tumor-targeted near-infra-red fluorescence (NIRF) imaging and the delivery of cytotoxins to tumor cells by endocytosis are described in this study. Nanoplatelets with an average diameter of 200 nm were prepared by mild sonication of kabiramide C (KabC)-loaded human platelets. The sealed plasma membrane of the nanoplatelets allows them to accumulate and retain membrane-permeable chemicals, such as epidoxorubicin (EPI) and KabC. Tumor-targeted imaging functionalities were engineered on the nanoplatelets by surface-coupling transferrin, Cy5 and Cy7. High-resolution fluorescence imaging and flow cytometry analyses showed that the nanoplatelets loaded with EPI and Cy5 targeted human myeloma cells (RPMI8226 cells) that over-expressed the transferrin receptor. The endocytosis of the nanoplatelets by RPMI8226 cells was transferrin-dependent and induced apoptosis. The test results also showed that the nanoplatelets functionalized with transferrin and Cy7 and injected in mice bearing RPMI8226 cells-derived myeloma xenotransplants accumulated in the tumor tissue and could be used for high-contrast in vivo NIRF imaging of early-stage tumors. Nanoplatelets represent a new class of living nano-vehicles that may efficiently target and deliver therapeutic agents and imaging probes to diseased tissues including tumors.

Extracellular Vesicles from Ocular Melanoma Have Pro-Fibrotic and Pro-Angiogenic Properties on the Tumor Microenvironment

Uveal melanoma (UM) is the most common primary intraocular tumor and often spreads to the liver. Intercellular communication though extracellular vesicles (EVs) plays an important role in several oncogenic processes, including metastasis, therapeutic resistance, and immune escape. This study examines how EVs released by UM cells modify stellate and endothelial cells in the tumor microenvironment. The surface markers, and the concentration and size of EVs derived from UM cells or choroidal melanocytes were characterized by high-resolution flow cytometry, electron microscopy, and Western blotting. The selective biodistribution of EVs was studied in mice by fluorescence imaging. The activation/contractility of stellate cells and the tubular organization of endothelial cells after exposure to melanomic EVs were determined by traction force microscopy, collagen gel contraction, or endothelial tube formation assays. We showed that large EVs from UM cells and healthy melanocytes are heterogenous in size, as well as their expression of phosphatidylserine, tetraspanins, and Tsg101. Melanomic EVs mainly accumulated in the liver and lungs of mice. Hepatic stellate cells with internalized melanomic EVs had increased contractility, whereas EV-treated endothelial cells developed more capillary-like networks. Our study demonstrates that the transfer of EVs from UM cells leads to a pro-fibrotic and pro-angiogenic phenotype in hepatic stellate and endothelial cells.

Teloxantron inhibits the processivity of telomerase with preferential DNA damage on telomeres

Telomerase reactivation is one of the hallmarks of cancer, which plays an important role in cellular immortalization and the development and progression of the tumor. Chemical telomerase inhibitors have been shown to trigger replicative senescence and apoptotic cell death both in vitro and in vivo. Due to its upregulation in various cancers, telomerase is considered a potential target in cancer therapy. In this study, we identified potent, small-molecule telomerase inhibitors using a telomerase repeat amplification protocol assay. The results of the assay are the first evidence of telomerase inhibition by anthraquinone derivatives that do not exhibit G-quadruplex-stabilizing properties. The stability of telomerase in the presence of its inhibitor was evaluated under nearly physiological conditions using a cellular thermal shift assay. Our data showed that the compound induced aggregation of the catalytic subunit (hTERT) of human telomerase, and molecular studies confirmed the binding of the hit compound with the active site of the enzyme. The ability of new derivatives to activate DNA double-strand breaks (DSBs) was determined by high-resolution microscopy and flow cytometry in tumor cell lines differing in telomere elongation mechanism. The compounds triggered DSBs in TERT-positive A549 and H460 lung cancer cell lines, but not in TERT-negative NHBE normal human bronchial epithelial and ALT-positive U2OS osteosarcoma cell lines, which indicates that the induction of DSBs was dependent on telomerase inhibition. The observed DNA damage activated DNA damage response pathways involving ATM/Chk2 and ATR/Chk1 cascades. Additionally, the compounds induced apoptotic cell death through extrinsic and intrinsic pathways in lung cancer cells. Taken together, our study demonstrated that anthraquinone derivatives can be further developed into novel telomerase-related anticancer agents.