Flow Cytometry Research Articles

Abstract B070: Dissecting EV dynamics in the sequestration of doxorubicin from breast cancer cells

Abstract Background: Extracellular vesicles (EVs) are one of the three main analytes sought for in liquid biopsy development. EVs are released by all cell types including cancer cells and play a crucial role in cell-cell communication. Breast cancer cells have been shown to utilize EVs as a mechanism to sequester chemotherapeutic agents, thereby conferring resistance to treatment. This study investigates the role of EVs in doxorubicin (DOX) resistance in MDA-MB-231 breast cancer cells. Method: MDA-MB-231 cells were exposed to increasing dose of anthracycline for 6 and 12 months. Resistance was confirmed by cytotoxicity assay and western blot. Resistant and parent cells were labeled for immunohistochemistry and their EVs were isolated via ultracentrifugation. EVs were analysed using nanoscale flow cytometry and sent for mass spectrophotometry. Result: Using nanoscale flow cytometry, we optimized a method to detect DOX-carrying EVs based on the intrinsic fluorescence of the drug. We found that DOX-resistant cells exhibited lower intracellular DOX accumulation and higher expression of the EV marker CD63 compared to their parental counterparts. Conclusion: These results suggest that chemoresistant breast cancer cells may alter their EV production machinery to evade the lethal effects of DOX. Understanding this mechanism could lead to novel strategies to overcome chemoresistance in breast cancer. Citation Format: Sina Halvaei, Jing Xu, Suganthi Chittaranjan, Sharon Gorski, Karla Williams. Dissecting EV dynamics in the sequestration of doxorubicin from breast cancer cells [abstract]. In: Proceedings of the AACR Special Conference: Liquid Biopsy: From Discovery to Clinical Implementation; 2024 Nov 13-16; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2024;30(21_Suppl):Abstract nr B070.

EhRacM differentially regulates macropinocytosis and motility in the enteric protozoan parasite Entamoeba histolytica.

Macropinocytosis is an evolutionarily conserved endocytic process that plays a vital role in internalizing extracellular fluids and particles in cells. This non-selective endocytic pathway is crucial for various physiological functions such as nutrient uptake, sensing, signaling, antigen presentation, and cell migration. While macropinocytosis has been extensively studied in macrophages and cancer cells, the molecular mechanisms of macropinocytosis in pathogens are less understood. It has been known that Entamoeba histolytica, the causative agent of amebiasis, exploits macropinocytosis for survival and pathogenesis. Since macropinocytosis is initiated by actin polymerization, leading to the formation of membrane ruffles and the subsequent trapping of solutes in macropinosomes, actin cytoskeleton regulation is crucial. Thus, this study focuses on unraveling the role of well-conserved actin cytoskeleton regulators, Rho small GTPase family proteins, in macropinocytosis in E. histolytica. Through gene silencing of highly transcribed Ehrho/Ehrac genes and following flow cytometry analysis, we identified that silencing EhracM enhances dextran macropinocytosis and affects cellular migration persistence. Live imaging and interactome analysis unveiled the cytosolic and vesicular localization of EhRacM, along with its interaction with signaling and membrane traffic-related proteins, shedding light on EhRacM's multiple roles. Our findings provide insights into the specific regulatory mechanisms of macropinocytosis among endocytic pathways in E. histolytica, highlighting the significance of EhRacM in both macropinocytosis and cellular migration.

Abstract 4140181: Mechanisms of SGLT-2 Inhibitor Empagliflozin in Attenuating Intramitochondrial Stress and Restoring Mitochondrial Function in Hyperglycemic Cardiomyocyte

Systemic hyperglycemia causes tissue damage and triggers cardiovascular disease (CVD). Sodium-glucose cotransporter-2 inhibitors (SGLT-2i) are a novel class of glucose-lowering agents that have shown unexpected benefits in clinical trials for the treatment of CVDs. We aim to investigate the underlying mechanisms of how SGLT-2 inhibitors alleviate CVDs associated with elevated glucose stress. iPSC-derived cardiomyocytes (iPSC-CM) were incubated with high glucose concentrations for 72 hours. Mitochondrial function in these cardiomyocytes was assessed by flow cytometry with JC-1 staining and ATP luminescence assay. Intracellular reactive oxygen species (ROS) and intramitochondrial calcium stress were measured using CellROX, MitoSOX, and Rhod-2 AM staining. Patch clamp was employed to determine ion current changes in the cardiomyocytes. Mitochondrial oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) were determined using the Seahorse XFe96 analyzer. In addition, qPCR, Western blot, and DM mouse heart histological analysis were performed to assess the regulation of associated molecules. The results indicated that exposure to a high glucose environment caused cardiomyocyte injury and impaired mitochondrial biosynthesis. Empagliflozin exhibited a beneficial effect on mitochondrial function by reducing ROS production and calcium deposition. It also mitigated the reduction in respiratory OCR of cardiomyocytes induced by high glucose incubation. Furthermore, molecular analysis revealed that Empagliflozin attenuated the dysregulation of mitochondrial calcium channels and biosynthesis by reducing associated gene expression, including Bcl2 , Mfn1 , Mx2 , Oas1 , Ant3 , Mcu , Micu1 , Vdac1 , Ryr2 , and Cypd-ppid . Histological analysis of DM mouse hearts demonstrated that reduced MFN2 and ZBP1 were target molecules for hyperglycemia-induced reduction of calcium channel currents in cardiomyocytes and could be restored by Empagliflozin treatment. This study concludes that high glucose stress diminishes mitochondrial calcium channel regulators MFN2 and ZBP1 in cardiomyocyte, which reduces calcium channel currents and leads to sensitization of cardiomyocyte to arrhythmogenesis, resulting in VT/VF. It provides experimental evidence for the clinical efficacy of Empagliflozin in ameliorating CVDs and managing diabetes-related CVDs.

HSP90 Complex From OLP Lesion Induces T-Cell Polarization via Activation of Dendritic Cells.

To investigate the effects of the heat shock protein 90 (HSP90) complex from oral lichen planus (OLP) lesion tissues on dendritic cell (DC) activation and the polarization of naïve T cells. Expression of HSP90 in OLP lesions and healthy control (HC) mucosa was evaluated by single-cell RNA sequence, IHC, qRT-PCR, and immunoblotting. HSP90 complex was extracted by immunoprecipitation from oral mucosa as the agonist of DCs. Expression of IFN-α and MHC was detected by flow cytometry. After cocultured with pre-stimulated DCs, polarization of naïve T cells was investigated by cytokine analysis. HSP90 was significantly higher in the lamina propria of OLP lesion and closely related to lymphocyte infiltration. HSP90 complex of OLP lesion activated DCs via TLR9 and increased their IFN-α secretion and MHC II expression. Pre-stimulated DCs increased the proportion of Th17 cells. HSP90 complex isolated from OLP lesion activated TLR9/IFN-α of DCs and further promoted the polarization of naïve T cells toward Th17 immunity.

Can flow cytometry be a key in the difficult diagnosis of coeliac disease?

We present the clinical case of a 39-year-old woman with a medical history of juvenile idiopathic arthritis and uveitis, evaluated for abdominal pain and distension, difficulty gaining weight, and diarrhea. Blood tests were requested, including antibodies which were negative and common genetic markers, showing positivity for HLA DQ 7.5. A gastroscopy with duodenal biopsies revealed findings consistent with stage 3b of the modified Marsh classification. Due to diagnostic uncertainty, an IEL study was performed, showing a characteristic CD pattern, leading to the initiation of a strict gluten-free diet (GFD). During follow-up, the patient showed partial improvement, with persistent digestive symptoms. A repeat endoscopic study revealed persistent atrophy, but refractory disease type 2 was ruled out. During a flare of rheumatologic disease, Tocilizumab was initiated by Rheumatology, resulting in improvement of duodenal atrophy.

SSX2IP promotes cell proliferation and migration in breast cancer by regulating FANCI.

Synovial sarcoma X breakpoint 2 interacting protein (SSX2IP) is expressed in various normal tissues and participates in the progression of human cancers. Nevertheless, the specific functions and underlying molecular mechanisms of SSX2IP in cancer, particularly in breast cancer, remain poorly understood. In this study, we aimed to explore the functional role of SSX2IP in breast cancer. Immunohistochemical staining, quantitative real-time PCR, and western blotting blot analysis were used to assess genes expression levels. By manipulating SSX2IP expression levels and conducting functional assays including Celigo cell counting assay or CCKCCK-8-8 assay, flow cytometry, wound healing assay, and Transwell assay, we explored the impact of SSX2IP on the malignant phenotype of breast cancer cells. Additionally, the in vivo tumor-suppressive ability of SSX2IP was investigated by tumor xenograft experiment. Our results revealed an upregulation of SSX2IP in the breast cancer. Functional assays demonstrated that SSX2IP knockdown inhibited cell proliferation and migration, induced apoptosis in vitro, as well as suppressed the tumor growth in vivo. Conversely, SSX2IP overexpression contributed to the malignant phenotype of breast cancer cells. Co-expression analysis showed that FA Complementation Group I (FANCI) was co-expressed with SSX2IP. Additionally, SSX2IP positively regulated FANCI expression and its interaction was verified by Co-IP.Co-IP. Furthermore, FANCI overexpression partially reversed the effects of SSX2IP knockdown on cell proliferation and metastasis. In summary, our findings revealed that SSX2IP contributes to the progression of breast cancer by regulating FANCI, hinting at its potential as a novel biomarker and therapeutic target for the treatment of breast cancer.

Abstract 4136847: Administration of the Recombinant Activated Protein C Rescues the Cardiac Vulnerability to Ischemic Insults in Aging through Modulating Inflammatory Response during Ischemia and Reperfusion

Introduction: Activated protein C (APC) is an endogenous vitamin-K-dependent serine protease and exhibits therapeutic potential for ischemic heart disease. The APC derivatives with anticoagulant and/or cytoprotective properties were produced through chemical engineering to characterize the functional domain of APC for limiting ischemia/reperfusion (I/R) injury. Hypothesis: The thromboinflammatory regulation by APC ameliorates ischemic insults caused by I/R through the receptor EPCR/PAR1. Methods: Young (3 months)/aged (24 months) wild type C57BL/6J mice and PAR1 R46Q/R46Q (block cleavage by APC) knock in mutant (3 months, C57BL/6J) mice were subjected to ligation of left anterior descending coronary artery with 45 min of ischemia. 5 min prior to reperfusion, wild type APC, cytoprotective selective APC-2Cys, or anticoagulant selective APC-E170A (0.2 μg/kg i.v.) was administered followed by 24 hr of reperfusion. The left ventricles of hearts were used for immunoblotting and flow cytometry analysis. Results: APC and APC-2Cys but not APC-E170A reduced I/R-induced myocardial infarction. Echocardiography showed that APC and APC-2Cys but not APC-E170A can rescue systolic dysfunction by I/R in young/aged WT but not in PAR1 R46Q/R46Q mice. Biochemical analysis showed that administration of APC and APC-2Cys inhibited activation of inflammation signaling c-Jun N-terminal protein kinase (JNK) and NF-κB by I/R and reduced mRNA levels of the proinflammatory cytokines TNFα and IL-6 in young/aged WT but not in PAR1 R46Q/R46Q hearts. The plasma cytokine array demonstrated that APC and APC2-Cys reduced potency of pro-inflammatory cytokines and apoptotic signaling cytokines during I/R. Moreover, I/R-triggered inflammasome NLRP3 was reduced by APC and APC-2Cys in young/aged WT but not in PAR1 R46Q/R46Q hearts. The flow cytometry showed that APC and APC-2Cys increased lymphocyte and decreased myeloid cell abundance and increased the recruitment of inflammation-mediating CD8a + T-cells during I/R in young/aged WT but not PAR1 R46Q/R46Q hearts, indicating that the APC/EPCR/PAR1 axis mediates APC's immune regulation under I/R. Moreover, APC and APC-2Cys reduced I/R-triggered macrophage abundance in young/aged WT hearts, although the proportion of M1 and M2 macrophages was unchanged. Conclusions: The cytoprotective domain of APC is critical for its cardioprotection against ischemic insults. EPCR/PAR1 receptor complex mediates APC's immune regulation in aging during I/R conditions.

Abstract 4137500: The Histone Methyltransferase MLL1 Regulates Notch Signaling and T Cell Phenotype During Pathologic Abdominal Aortic Aneurysm Development

Objective: Abdominal aortic aneurysms (AAA) are characterized by pathological vascular remodeling and an imbalance between anti-inflammatory regulatory T H cells (Tregs) and pro-inflammatory T H 17 cells within the aortic wall. The mechanisms regulating CD4 + T H cell differentiation during AAA development remain unknown. Recently, the histone methyltransferase, mixed lineage leukemia 1 (MLL1), has been shown to influence T H cell phenotype by directly altering key transcription factors for T H 17 (RORγ) and Treg (FOXp3) differentiation in varying disease states. As such the objective of this study was to evaluate the role of MLL1 in promoting T H 17 activity within AAA development and to determine key T H 17 cell signaling pathways that are altered Methods: Single-cell sequencing was conducted on human AAAs and control tissue samples. For our murine model, C57BL/6 mice were injected with an AAV encoding a PCSK9 gain-of-function mutation and fed a saturated fat diet followed by either AngII infusion to induce AAAs (1 µg/kg/min) or saline. Mice with T-cell specific deletion of Notch1 signaling (Notch1 f/f CD4 cre+ ) or MLL1 ( Mll1 f/f CD4 cre+ ) were subjected to the AngII-induced AAA model and AAA diameters quantified. CD4+ T-cells were isolated by MACs and gene expression analyzed by qPCR as well as T-cell phenotype by flow cytometry. ChIP was used to evaluate histone 3 lysine trimethylation (H3K4me3). Results: Single-cell RNA sequencing of human aortic tissue revealed that the epigenetic enzyme MLL1 and Notch1 signaling were profoundly upregulated in human AAA CD4+ cells compared to non-aneurysmal control samples. Congruently, CD4 + T H cells isolated from the murine AngII-induced AAA model displayed a predominance of T H 17 phenotype and elevated expression of MLL1. Histone methylation was evaluated by ChIP in AngII-induced AAA CD4+ cells and demonstrated increased levels of the MLL1-mediated activation histone methylation mark, H3K4me3, on the Notch 1 promoter. Mice deficient in CD4 + T H cell Notch signaling ( Notch1 f/f CD4 cre+ ) or MLL1 ( Mll1 f/f CD4 cre+ ) subjected to the AngII-induced murine model displayed significant reduction AAA development (n=10/group, p<0.05) with decreased CD4+ T H 17 cell activity and reciprocal increase in Treg expression. Conclusions: MLL1, a histone methyltransferase, regulates Notch1 signaling and T-cell differentiation in AAA development, causing pathologic inflammation. This pathway may serve as a potential therapeutic target to prevent aortic dilation.

Abstract 4132968: CCR5 modulation enhances M-MDSCs functionality in early atherosclerosis

Background: The role of immune suppressive microenvironment, promulgated by the presence of Myeloid Derived Suppressor Cells (MDSC) have been the major focus of research delineating the underlying mechanisms of cardiovascular diseases (CVD). CCR5, a chemokine receptor, has been associated with both immunosuppressive and inflammatory phenotypes, however, the possible role of CCR5 pertaining to MDSCs in the development of atherosclerosis has not been elucidated yet. Therefore, we investigated the therapeutic potential of CCR5 modulation in early atherosclerosis progression. Methods: CCR5 receptor-ligand expression was studied with flow cytometry, real time PCR and immunocytochemistry in 65 individuals (25 Healthy controls, 20 young hypercholesterolemic individuals, and 20 stable [Coronary Artery Disease] CAD patients). To induce atherosclerosis, mice were fed high fat diet (HFD) for 6 weeks following partial ligation of left carotid artery in C57BL6 mice. MDSCs phenotype and functionality were assessed using CCR5 inhibitor in vitro (10 -8 M) and in vivo (i.p 3ng/day for 15 days) . M-MDSCs phenotype switch, atherosclerotic lesion development and plaque phenotype was studied in vivo . Results: We observed CCR5 elevation on Monocytic-MDSCs in the early phase of atherosclerosis. M-MDSCs displayed an intermediate phenotype with expression of both pro and anti-inflammatory mediators in early atherosclerosis, a similar trend was observed in inflammatory cytokines stimulated M-MDSCs ( in vitro ). Notably, DAPTA treatment shifted phenotype of M-MDSCs to anti-inflammatory profile with elevated expression of IL-10 and reduced expression of IFNγ, IL4, and IL22. Further, CCR5 modulation expanded IL10+M-MDSC in vivo . Additionally, DAPTA reduced the migratory potential, reduced cholesterol uptake and improved the functionality (suppression of T cell) of M-MDSCs. Blocking CCR5 with DAPTA led to the formation of stable plaque in HFD-fed mice. Conclusion: Increased expression of CCR5 coupled with inflammatory cytokine secretion by regulatory cells lead to dysfunctional M-MDSCs in CVD risk factor population. Possibly this dysfunctionality contributes to the development and progression of CVD including atherosclerosis. Our findings show targeting of CCR5 with DAPTA reduces atherogenesis, increases plaque stabilization and corrects phenotypic alterations in immune suppressive M-MDSCs. The functionality and phenotype of M-MDSCs in atherosclerosis, may be ameliorated by targeting CCR5.

Development of bombesin-tubulysin conjugates using multicomponent chemistry to functionalize both the payload and the homing peptide

Peptide-drug conjugates (PDCs) have recently gained significant attention for the targeted delivery of anticancer therapeutics, mainly due to their cost-effective and chemically defined production and lower antigenicity compared to ADCs, among other benefits. In this study, we designed and synthesized novel PDCs by conjugating new thiol-functionalized tubulysin analogs (tubugis) to bombesin, a peptide ligand with a relevant role in cancer research. Two tubulysin analogs bearing ready-for-conjugation thiol groups were prepared by an on-resin multicomponent peptide synthesis strategy and subsequently tested for their stand-alone in vitro anti-proliferative activity against human cancer cells, which resulted in IC50 values in the nanomolar range. In addition, various fluorescently labeled [K5]-bombesin(6–14) peptides, non-lipidated and lipidated with fatty acid chains of variable length, were also synthesized using the versatile multicomponent chemistry. These bombesin derivatives were tested for their gastrin-related peptide receptor (GRPR)-mediated internalization into cancer cells using flow cytometry, proving that the lipid tail (especially C14) enhances the cell internalization. Using the tubugi toxins and bombesin peptides, three different bombesin-tubugi conjugates were synthesized with different cleavage propensity and lipophilicity. Preliminary in vitro experiments revealed that, depending on the linker and the presence of a lipid tail, these novel PDCs possess good to potent anticancer activity and moderate selectivity for GRPR-overexpressing cancer cells.

Abstract 4136532: The Agonism of Macrophage Migration Inhibitory Factor Modulates Neutrophils Subsets and Rescues an Impaired Tolerance to Ischemic Insults in Aging

Introduction: An impaired cardiac macrophage migration inhibitory factor (MIF) signaling in aging during ischemia and reperfusion (I/R) can be rescued by a MIF agonist, MIF20. Alterations in cardiac metabolic homeostasis cause inflammation under I/R. Thus, MIF agonism with MIF20 could modulate cardiac inflammatory response during I/R. Hypothesis: MIF20 modulates the polarization of neutrophil subset and rescues the impaired immune response under I/R in aging. Methods: Young (3-months)/aged (24 months) C57BL/6 wild type (WT) mice and MIF flox/flox (3 months)/cMIF -/- (cardiomyocyte MIF deletion, 3 months) were subjected to LAD ligation of for 45 min of ischemia, followed by 24 hr of reperfusion. MIF20 (0.15 µg/kg, i.v.) was injected at 5 minutes before reperfusion. The immune cells were determined with flow cytometry. mRNA and protein were measured by real-time qPCR, immunoblotting/cytokine array. Results: Administration of MIF20 reduced myocardial infarct by I/R in young/aged WT and MIF flox/flox but not in cMIF -/- mice. The flow cytometry showed that I/R stress dramatically triggered neutrophils infiltration, which occurred in both left ventricle and right ventricle. Intriguingly, MIF20 treatment reduced the I/R-induced neutrophil recruitment in hearts. Aged versus young WT myocardium recruited more N1 neutrophils (CD206 - ), while MIF20 treatment rescued the impaired N1 neutrophils response in aging. Moreover, MIF20 can increase infiltration of N2 neutrophils (CD206 + ) in both young and aged WT hearts. The recombinant MIF can directly trigger N2 neutrophil polarization and N1 neutrophil reduction in cMIF -/- hearts, indicating the critical role of MIF/CD74 axis in neutrophil polarization by I/R challenge. The cytokine array showed that MIF20 treatment can trigger cardiac TGF-β levels and upregulate IL-10 levels in serum under I/R, since TGF-β and IL-10 are critical factors involved in the N2 neutrophils’ polarization. Interestingly, MIF20 increased SiglecF marker on neutrophils in the aged versus young hearts, suggesting that MIF20 rescue the long-lived neutrophil population (SiglecF high ) which could enhance phagocytosis to repair damaged myocardium during I/R conditions. Conclusions: An impairment of metabolic homeostasis and inflammatory response occurred in cardiac aging. MIF agonism with small molecule MIF20 can rescue the capacity of MIF/CD74 signaling to maintain metabolic homeostasis and inflammatory response in aging under I/R pathological conditions.

CD34+ and CD34- MM cells show different immune-checkpoint molecule expression profiles: high expression of CD112 and CD137 ligand on CD34+ MM cells.

Despite the introduction of new drugs, multiple myeloma (MM) still remains incurable. We previously reported that CD34+ MM cells, which are clonogenic and self-renewing, are therapy-resistant and persist as a major component of minimal residual disease, expanding during relapse. To investigate the effects of immunotherapies such as immune-checkpoint inhibitors, CAR-T therapy, and bispecific antibodies on CD34+ MM cells, we analyzed immune profiles of both MM cells and T cells from MM patients using microarrays and flow cytometry. Ingenuity pathway analysis revealed 14 out of 289 canonical pathways were more active in CD34+ MM cells compared to CD34- cells, many of which were involved in inflammation and immune responses. Notably, PD-1 signaling-related genes were highly expressed in CD34+ MM cells. Among 10 immune-checkpoint molecules, CD34+ cells more frequently expressed CD112, CD137L, CD270, CD275, and GAL9 than CD34- cells in both newly diagnosed and relapsed/resistant patients. In addition, CD4+ and CD8+ T cells more frequently expressed TIGIT and CD137, suggesting that CD112/TIGIT and CD137L/CD137 interactions may suppress T-cell activity against CD34+ MM cells. Furthermore, our finding of higher FcRH5 expression on CD34+ MM cells is encouraging for future research into the efficacy of FcRH5-targeted therapy in MM.

Abstract 4134426: Targeting the TRIM29-PERK signaling axis for treating viral myocarditis

Introduction: Viral myocarditis is an inflammatory disease of the myocardium that significantly contributes to sudden death in children and young adults. The COVID-19 pandemic underscores the critical need to understand the pathogenesis and develop effective treatment strategies for viral myocarditis. Methods: To investigate the role of the novel E3 ligase TRIM29 in viral myocarditis, we used wild-type and TRIM29 knockout mice infected with coxsackievirus B3 (CVB3) and encephalomyocarditis virus (EMCV), to induce the myocarditis. Additionally, wild-type mice infected with CVB3 were treated with the protein kinase RNA-like endoplasmic reticulum kinase (PERK) inhibitor GSK2656157 or a DMSO control to evaluate potential therapeutic interventions. Mice survival and heart function were monitored using transthoracic echocardiography, and hearts were harvested for histological and immunohistochemical analysis. Techniques including real-time PCR, western blotting, co-immunoprecipitation, enzyme-linked immunoassay, flow cytometry, over-expression, and knockdown were employed to elucidate the pathogenic mechanisms by which TRIM29 regulates the endoplasmic reticulum stress response after viral infection. Results: We found that TRIM29 was highly induced by cardiotropic viruses, including CVB3 and EMCV, and promoted PERK-mediated endoplasmic reticulum (ER) stress, apoptosis, and reactive oxygen species (ROS) responses, which restricted viral replication in cardiomyocytes in vitro . TRIM29 deficiency protected mice from viral myocarditis by enhancing cardiac antiviral functions and reducing PERK-mediated inflammation and immunosuppressive cells in vivo . Mechanistically, TRIM29 interacted with PERK to catalyze the SUMOylation of PERK, maintaining its stability and thereby promoting PERK-mediated signaling pathways. Furthermore, we demonstrated that the PERK inhibitor GSK2656157 mitigated viral myocarditis by disrupting the TRIM29-PERK interaction, which improved cardiac function, enhanced cardiac antiviral responses, and reduced inflammation and immunosuppressive cells in vivo . Conclusions: Our findings provide the first evidence that the TRIM29-PERK signaling axis can be targeted for the treatment of viral myocarditis. This suggests that targeting the TRIM29-PERK axis could effectively mitigate viral myocarditis and associated cardiovascular diseases.

Niosomal gel improves dermal delivery of nimbolide: a promising approach for treatment of psoriasis.

Aim: Psoriasis is a chronic inflammatory skin disorder characterized by the excessive proliferation of keratinocytes, forming thickened skin plaques due to immune-mediated cytokine responses. Delivering drugs through this barrier to target inflamed tissues remains challenging. Nimbolide (NIM), known for its anti-inflammatory and anticancer properties, shows promise in managing psoriasis. However, its efficacy is limited by its inability to penetrate the thickened horny layer of the skin. To overcome this obstacle, we have developed Nim-loaded niosomal (Nio) formulations (NIM Nio) aimed at improving dermal delivery and achieving localized sustained release at psoriasis-affected sites.Methods: The formulation characteristics were assessed using Zeta sizer, Transmission Electron Microscopy (TEM), and High-performance liquid chromatography (HPLC). The optimized formulation was evaluated for anti-psoriatic potential compared to Nim alone by using molecular techniques such as Confocal Microscopy, Flow cytometry, enzyme-linked immunosorbent assay (ELISA), and Western blotting.Results: NIM Nio showed effective penetration into psoriatic skin, resulting in reductions in keratinocyte hyperproliferation, oxidative stress, splenomegaly, inflammatory cytokines, Psoriasis Area and Severity Index (PASI), and rete ridges compared to NIM alone.Conclusion: Our findings underscore the significant anti-proliferative, antioxidant, and anti-inflammatory properties of NIM Nio in psoriasis, demonstrating its potential as a promising therapeutic option for this challenging condition.

Abstract 4115947: Empagliflozin Inhibits the Mobilization of CCR2+ Monocyte-Derived Macrophages by Reducing CCL2 Expression in Fibroblasts and Slows the Progression of Heart Failure After Pressure Overload.

Background: The positive effects of sodium glucose co-transporter-2 (SGLT2) inhibitors on reducing cardiovascular mortality and hospitalizations due to heart failure have been well established. Although numerous theories propose explanations for the cardioprotective actions of SGLT2 inhibitors, these hypotheses primarily rely on initial findings and require further validation. Studies have shown that immune cells, particularly macrophages marked by C-C chemokine receptor type 2 (CCR2), contribute to the progression of heart failure by infiltrating the myocardium and inducing detrimental structural changes following myocardial infarction or pressure overload. Purpose: This study aims to investigate whether SGLT2 inhibitors can mitigate heart damage by inhibiting the migration of CCR2+ monocyte-derived macrophages. Methods: In this experiment, male B6 mice were subjected to transverse aortic constriction (TAC) to induce heart failure. Two weeks post-TAC, with heart function confirmed as equal across all groups by echocardiography, one group began receiving daily oral doses of empagliflozin, while another served as the control. At four weeks post-TAC, cardiac function was reassessed. The animals were then euthanized, and their hearts were analyzed using flow cytometry, staining, and qPCR to evaluate heart failure and the involvement of immune cells. Additionally, isolated cardiac fibroblasts were subjected to cyclic stretching to mimic post-TAC mechanical stress. Results: Treatment with empagliflozin resulted in improved cardiac function and reduced congestion in the heart and lungs, indicating alleviation of heart failure. The treatment notably decreased myocardial fibrosis, evident from Picrosirius-red staining and reduced expression of fibrosis-related mRNA. Importantly, empagliflozin specifically reduced the number of CCR2-positive macrophages in the heart, without affecting other types of immune cells. In cardiac fibroblasts that underwent cyclic stretching, empagliflozin pre-treatment diminished the expression of C-C motif chemokine ligand 2 (CCL2), the ligand for CCR2. Conclusion: Empagliflozin’s ability to suppress CCL2 expression in fibroblasts and curtail the recruitment of CCR2+ macrophages may represent a potential strategy to decelerate heart failure progression. These findings advance our understanding of the cardioprotective mechanisms of SGLT2 inhibitors and propose novel therapeutic avenues for heart failure management.

Abstract 4119680: First-in-Man Treatment of Heart Failure by Repeated Intravenous Infusions of a Cardiovascular Cell-Derived Extracellular Vesicle-Enriched Secretome

Background: Most of the effects of intramyocardially transplanted stem cells can be duplicated by the sole administration of their secretome but this approach has not yet been tested in heart failure (HF). Methods: The SECRET-HF phase I trial (NCT05774509) was designed according to a Bayesian optimal interval scheme to assess the effects of repeated intravenous infusions of a cellular secretome in 12 patients with a non-ischemic dilated cardiomyopathy. The main inclusion criteria are severe symptoms (NYHA Class III despite an optimal guideline-directed medical therapy), a reduced left ventricular (LV) ejection fraction (EF ≤40%) and ineligibility for a heart transplant. The Investigational Medicinal Product was derived from human induced pluripotent stem cells reprogrammed from a healthy donor and differentiated in cardiovascular progenitor cells (CPC). Following CPC culture in a dedicated "vesiculation" medium, the conditioned media were collected, filtered, enriched for extracellular vesicles, concentrated by tangential flow filtration and scaled out into glass vials stored at -80°C. Quality controls were implemented throughout the whole process which was conducted according to current Good Manufacturing Practices. Results: Three patients, out of the 4 of the initial low-dose cohort, have now been treated. All had been previously fitted with an automatic internal cardioverter defibrillator (AICD). The secretome was delivered intravenously 3 times, 3 weeks apart, at a dose of 20 x10 9 particles/kg for each infusion. By November, 2024, the follow-up will be 16, 9, 6 and 2 months for each of them (mean: 8 months). So far, none of the treated patients has experienced a dose-limiting toxicity; in particular, there have been no post-treatments ventricular arrhythmia detected by the AICD, no allo-immunization and no inflammation based on the enumeration of lymphocyte subpopulations by flow cytometry. At 6 months, the first patient improved to NYHA Class II with a decrease in echographic LVEDV and LVESV (from 108 mL/m 2 to 87 mL/m 2 and from 80 mL/m 2 to 60 mL/m 2 , respectively) and a concomitant increase in LVEF from 25% to 32%. At 1 month post-treatment, the second patient also reports a symptomatic improvement (NYHA Class II) with an increase in EF from 21% to 28%. Conclusions: This initial experience supports the safety of repeated intravenous administrations of a cardiovascular cellular secretome as a potential noninvasive and user-friendly treatment of severe HF.

E'jiao and Cubilose Formula Induced Antioxidant Activity and Improved Collagen Expression of Human Skin Fibroblasts During Oxidation Damage.

As traditional Chinese medicinal materials, E'jiao and cubilose are rich in various bioactive substances with good antioxidant, anti-inflammatory, and immune-regulating effects. To obtain the optimal ratio of synergistic effect between E'jiao and cubilose. The antioxidant capacity of E'jiao and cubilose digestive fluid was evaluated invitro, as well as the intracellular oxidation balance between HSF cells and 3D whole-skin model induced by H2O2. E'jiao, cubilose, and their different ratios of composites had better scavenging ability against free radicals such as DPPH (2,2-Diphenyl-1-picrylhydrazyl). Using HSF cells induced by H2O2 as an oxidative damage model, it was found that the combination of E'jiao and cubilose in a ratio of 2:3 significantly enhanced the activities of SOD, GSH-PX, and CAT enzymes compared to the separate treatments of E'jiao and cubilose, as well as other combination ratios. It effectively reduced the accumulation of reactive oxygen species caused by H2O2 in HSF (Human Skin Fibroblast)cells and protected the integrity of the cells. Further analysis using flow cytometry and a 3D full-thickness skin model revealed that the combination ratio of 2:3 increased the proportion of H2O2-treated cells in the S%+G2% phase from 19.1% + 7.4%-22.1% + 28.8%, helping oxidatively damaged cells partially recover their proliferative capacity. It also promoted the expression of collagen I and collagen IV in the 3D full-thickness skin model, with improvement rates reaching 168.00% and 123.68%, respectively. These findings indicate that the combination of E'jiao and cubilose in a ratio of 2:3 exhibits good synergistic effects, enhancing the ability of cells to resist oxidative damage, promoting cellular renewal and metabolism, and improving skin antiwrinkle capacity.

Abstract 4120741: Estrogen Regulates Abdominal Aortic Aneurysm Tregs via CD45 + Fibroblast-derived IL-33

Background: Sexual dimorphisms manifest during the progression of abdominal aortic aneurysm (AAA). Regulatory T cells (Tregs) are a subset of T cells characterized by their immunosuppressive and tissue-repairing functions, therefore playing a protective role in AAA. Aims: We aim to elucidate the mechanism underlying sexual dimorphism in Tregs presented in AAA aortas, which is significant for unraveling the pathogenesis of AAA and developing gender-specific therapeutic approaches. Methods and Results: AAA mice were induced by receiving porcine pancreatic elastase. By flow cytometry, we observed that ovariectomy (OVX) increased the ratio of Tregs in female mice, while estrogen led to a decrease in aortic Tregs. Additionally, compared to littermate controls, estrogen receptor α (ERα) KO mice exhibited an increase in Treg ratio. Similar results were observed for the ST2 + Treg ratio. IL-33, as an alarming molecule, can promote the maintenance of ST2 + Tregs in tissues. Western blot revealed lower IL-33 expression levels in female mice than in male mice. By analyzing the IL-33 expression profiles of various cells in AAA tissue, we found that IL-33 mainly originates from fibroblasts. We found two subpopulations of fibroblasts, CD45 + and CD45 - fibroblasts. Immunofluorescence on the aortas verified the presence of cells co-expressing CD45 and PDGFRα in AAA fragments. Furthermore, IL-33 expression only showed gender differences in CD45 + fibroblasts. Adoptive transfer of CD45.1 + mouse bone marrow macrophages into CD45.2 + mice revealed that aortic CD45.1 + cells could regain the PDGFRα phenotype, with a lower proportion of female PDGFRα + cells in CD45.2 - CD45.1 + cells than in male mice. Lyz2(cre/+); Rosa26(tdtomato/+) mice showed the presence of lyz2-tdtomato + cells expressing PDGFRα in the aortic adventitia after AAA induction. This suggests that CD45 + fibroblasts are partially derived from bone marrow macrophages, which can migrate to aneurysms and acquire a PDGFRα phenotype. Conclusions: Female sex hormones negatively regulate CD45 + fibroblast formation and IL-33 secretion between female and male mice during AAA. This resulted in reduced Treg function in female mice compared to male mice.

Abstract 4134384: Sotagliflozin, a Dual Inhibitor of Sodium-Glucose Transporters 1 and 2, Elicits Cardioprotective Effects Through Attenuation of Platelet Activation and Thrombosis

Sodium-glucose cotransporter (SGLT) inhibitors are used in the treatment of type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD). In the SCORED trial, sotagliflozin (SOTA), a dual SGLT1/2 inhibitor, demonstrated significant reductions in both myocardial infarction (MI) and stroke in patients with T2DM and CKD. These results suggest a cardiovascular (CV) benefit of SOTA in patients with T2DM and CKD who are at increased risk of thromboembolic disease. To investigate the underlying mechanism of CV protection, we evaluated the effects of SOTA on platelet activation and thrombus formation, in both in vivo and ex vivo models, to understand its effects on MI and stroke. Washed human platelets treated with SOTA were stimulated with various agonists and platelet activation was assessed via lumi-aggregometry and flow cytometry. In whole blood, SOTA was evaluated for its potential to reduce platelet adhesion and thrombus formation in the perfusion flow chamber and Total Thrombus formation Analysis System (TTAS) assays. In vivo , mice dosed with SOTA were assessed for thrombus formation at the site of injury in real-time in the cremaster arteriole injury model. To determine the effect of SOTA on hemostasis, we assessed coagulation parameters ex vivo in human whole blood using thromboelastography. Finally, bleeding time was measured in vivo in mice dosed with SOTA using the tail bleeding assay. In washed platelets, SOTA inhibits platelet activation and aggregation in a dose-dependent manner. Similarly, a dose-dependent decrease in platelet adhesion and thrombus formation was observed in whole blood assays. In vivo , platelet accumulation and fibrin formation were decreased in mice dosed with SOTA, however no effect is observed in coagulation parameters or bleeding time. SOTA inhibits platelet activation and thrombus formation with no impact on coagulation parameters or bleeding potential. These findings highlight a potential mechanism through which SOTA reduces the risk of stroke and MI in patients with T2DM and CKD, underscoring the importance of further investigation into the role of SOTA in CV protection, particularly in patients suffering from both T2DM and CKD at high risk of thromboembolic events.

Small heterodimer partner-interacting leucine zipper protein suppresses pain and cartilage destruction in an osteoarthritis model by modulating the AMPK/STAT3 signaling pathway.

Osteoarthritis (OA) is a degenerative joint disease caused by the breakdown of joint cartilage and adjacent bone. Joint injury, being overweight, differences in leg length, high levels of joint stress, abnormal joint or limb development, and inherited factors have been implicated in the etiology of OA. In addition to physical damage to the joint, a role for inflammatory processes has been identified as well. Small heterodimer partner-interacting leucine zipper protein (SMILE) regulates transcription and many cellular functions. Among the proteins activated by SMILE is the peroxisome proliferator-activated receptor (PPAR) γ, which mediates the activities of CD4 + T helper cells, including Th1, Th2, and Th17, as well as Treg cells. PPAR-γ binds to STAT3 to inhibit its transcription, thereby suppressing the expression of the NF-κB pathway, and in turn, the expression of the inflammatory cytokines interferon (IFN), interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α, which are sub-signals of STAT3 and NF-κB. OA was induced in control C57BL/6 mice and in C57BL/6-derived SMILE-overexpressing transgenic (SMILE Tg) mice. The protein expression levels in the joint and spleen tissues were analyzed by immunohistochemistry and immunofluorescence images. In addition, flow cytometry was performed for detecting changes of the changes of immune cells. Less cartilage damage and significantly reduced levels of OA biomarkers (MMP13, TIMP3 and MCP-1) were observed in SMILE Tg mice. Immunohistochemistry performed to identify the signaling pathway involved in the link between SMILE expression and OA revealed decreased levels of IL-1β, IL-6, TNF-α, and phosphorylated AMPK in synovial tissues as well as a significant decrease in phosphorylated STAT3 in both cartilage and synovium. Changes in systemic immune cells were investigated via flow cytometry to analyze splenocytes isolated from control and SMILE Tg mice. SMILE Tg mice had elevated proportions of CD4 + IL-4 + cells (Th2) and CD4 + CD25 + Foxp3 + cells (Treg) and a notable decrease in CD4 + IL-17 + cells (Th17). Our results show that overexpressed SMILE attenuates the symptoms of OA, by increasing AMPK signaling and decreasing STAT3, thus reducing the levels of inflammatory immune cells.