tbuckley/cabot-search huggingface dataset:
Abstract Tu148: cGAS-STING pathway promotes granulopoiesis and neutrophil differentiation in acute ischemia
Authors: Jiankun Zhu, pablo Parra, Xiang Luo, Dian Cao
Journal: Circulation Research (2024)

Contemporary evidence supports neutrophils' complex roles beyond being the simple and powerful destruction tools in MI. However, our understanding remains limited. We especially lack the knowledge of how cGAS-STING regulates neutrophil functions in acute ischemia. The cGAS-STING pathway senses cytosolic DNA to produce IFN and ISGs and is a pillar of innate immunity. Early evidence suggested neutrophils did not express cGAS. Taking advantage of the improved detecting method, we revisited this topic because this pathway can play an essential role in neutrophil function in MI. Using purified neutrophils from WT and knockout mice (as control), we detected cGAS, STING, and IRF3 in these cells. To determine if cGAS-STING regulates neutrophil function, we first generated MI model in cGAS -/- , STING -/- mice, and their WT littermates and performed flow cytometry and RNA-seq analyses. We uncovered that inhibiting cGAS-STING decreases neutrophil production in bone marrow (BM) after ischemia. Interestingly, cGAS- and STING-deficient neutrophils express significantly higher levels of primary granule molecules such as MPO, Prtn3, Elane, Cts- (s, g, b, l) but much lower levels of the secondary and tertiary granule components , including Mmp9, Mmp8, Olfm4, Cd177, Lyz2, and Lyz1. Neutrophils acquire granules sequentially during differentiation. Therefore, our data suggest inhibiting cGAS-STING leads to a stagnated neutrophil differentiation in the BM and mobilizes CD101 - immature neutrophils into the circulation and MI hearts. Consistently, cGAS- and STING-deficient neutrophils release less MMP8 and MMP9 into the ischemic area. Ischemia does not trigger the degranulation of primary granules, as indicated by the minimal changes of CD63. Our data further suggest that TF C/EBP𝜹 functions downstream of cGAS-STING to promote neutrophil differentiation. Adoptive transfer experiments suggest the neutrophil-specific function of cGAS-STING. In conclusion, we identify cGAS-STING as a novel mechanism promoting emergency granulopoiesis and neutrophil differentiation after MI and uncover its functional implications in ischemia-induced remodeling. Studies using Mrp8-Cre-mediated cGAS-STING deletion in granulocyte/macrophage progenitors are in progress.
Abstract Tu046: Mechanisms of Epicardium-Directed Cardiac Repair
Authors: David Wong, Matthew Tran, Helen Thome, Jenny Cheng, Elle Rathbun, Xia Yang, Pearl Quijada
Journal: Circulation Research (2024)

Background: In the adult heart, the epicardium becomes activated by myocardial infarction (MI), contributing to cardiac remodeling primarily through the secretion of paracrine factors. However, there is a limited understanding of the cellular and molecular mechanisms that govern epicardial function and promote pro-reparative signaling pathways. Thus, enhancing or restoring the pro-regenerative characteristics of the epicardium may benefit cardiac repair after MI. We hypothesize that epicardial-derived cells preserve cardiac function during ischemic injury through the limited secretion of pro-reparative paracrine factors, such as slit guidance ligand 2 (Slit2), which enhances angiogenesis and vascular stability. Methods: We used the Wt1 (Wilms Tumor 1) CreERT2 ; R26 tdTomato mouse line for tamoxifen-inducible epicardial-specific lineage tracing and Pdgfra nGFP to label cardiac fibroblasts ( Wt1 CreERT2 ; R26 tdT ; Pdgfra nGFP ). Tagged epicardial-derived cells (tdTomato + ) from sham and 7-day post-MI mice were isolated by fluorescence-activated cell sorting and sequenced by single-cell RNA sequencing. To delineate Slit2-directed cell and molecular mechanisms, we performed in vitro studies and utilized adeno-associated viral vectors for gene therapy in a mouse model of MI. Results: We identified 9 transcriptionally distinct epicardial subpopulations contributing to paracrine signaling induced by MI. We found enriched expression of various chemokines in epicardial-derived stromal cells, while genes associated with Wnt signaling and epithelial-to-mesenchymal transition (EMT) were highly expressed in Wt1 -expressing clusters. Isolated cardiac fibroblasts treated with an adenoviral vector expressing Slit2 exhibited no differences in myofibroblast formation or collagen production following treatment with activation stimuli (TGFβ1/Ang II) but showed significant increases in the expression of pro-angiogenic gene programs. Cardiac-targeted AAV9-Slit2 overexpression in mice subjected to MI led to a striking increase in cardiac ejection fraction, expression of angiogenic-modulating genes, vessel density, and endothelial cell proliferation but did not alter fibrotic deposition. Conclusions: Our study reveals the dynamic role of epicardial cells during the post-MI cardiac repair process and delineates a Slit2-Robo dependent mechanism governing cardiac fibroblast and endothelial cell crosstalk to modulate angiogenesis.
Abstract Tu141: Effect of Epicardial Application of Oxygenated Hydrogel on Scar Burden in a Rat Model of Myocardial Infarction
Authors: Ghazal Sanadgol, Jie Guo, Antonia van Kampen, Acile Nahlawi, Guillaume Goudot, Koushiar Yaghoubian, Jeremy Ruskin, Yu Shrike Zhang, Leon Ptaszek
Journal: Circulation Research (2024)

Background: Epicardial application of a bioadhesive at the time of experimental myocardial infarction (MI) has been shown to reduce ventricular scar burden in mice. This study assessed the impact of an oxygenated hydrogel (O 2 -hydrogel) on post-infarct cardiac function and scar burden in rats. Method: Experimental MI was performed in Lewis rats (age 12-15 weeks) by permanent ligation of the anterior interventricular artery. There were 3 cohorts in this study: 1. MI followed by epicardial application of hydrogel, 2. MI followed by epicardial application of O 2 -hydrogel, and 3. MI with no treatment. Left ventricular (LV) function was evaluated by transthoracic echocardiography (TTE) at baseline, immediately post-MI, and 3 weeks post-MI. LV scar burden was evaluated with histopathology performed 3 weeks post-MI. Result: Twenty-four rats were analyzed (hydrogel, n= 8; O 2 -hydrogel, n= 9; untreated, n=7). LV fractional shortening (FS) measured by TTE 3 weeks post-MI was significantly reduced compared with baseline in untreated rats (44.6±12.4 to 22.3±4.9, P=0.043; Figure 1) and hydrogel treated rats (32.4±6.0 to 14.9±5.2, P=0.018). No significant change in FS was observed in the O 2 -hydrogel treatment cohort (39.0±13.9 to 38.1±12.6, P=0.859). LV scar burden in the O 2 -hydrogel cohort was significantly lower than in the hydrogel alone and untreated cohorts (11.9% vs 39.9% and 36.2%, respectively; Figure 2). Conclusion: In this rat model, epicardial application of O 2 -hydrogel at the time of experimental MI is associated with greater preservation of LV function and significantly lower scar burden than application of hydrogel alone or no treatment.
Abstract Tu029: Effects of the phosphodiesterase inhibitors, cilostazol and ensifentrine, on alveolar-capillary dysfunction caused by MRSA
Authors: Mohammed Yaman AL Matni, Alison Ha, Steven Dudek, Eleftheria Letsiou
Journal: Circulation Research (2024)

Background: Acute lung injury (ALI) is characterized by excessive inflammation and dysfunction of the alveolar-capillary barrier, which consists of lung vascular endothelial and alveolar epithelial cells. Therapeutic interventions that protect this barrier are promising strategies for ALI treatment. Phosphodiesterase (PDE) inhibitors are potent modulators of inflammation. These include cilostazol, a PDE3 inhibitor, and ensifentrine, a dual PED3/4 inhibitor, which are both clinically available compounds that exhibit cytoprotective and anti-inflammatory properties. However, their roles in regulating alveolar-capillary function in ALI are unknown. The aim of this study is to investigate the effects of cilostazol and ensifentrine on lung endothelial and epithelial dysfunction caused by methicillin-resistant Staphylococcus aureus (MRSA), a common bacterial pathogen involved in ALI pathogenesis. Methods: Human primary lung endothelial cells (EC) and A549 (alveolar epithelial cell line) were pre-treated with cilostazol (CZ; 15 μM) or ensifentrine (Ens; 10 μΜ) for 1 hour and then challenged with heat-killed MRSA (2.5 x10 8 /ml). The Electrical Cell Impedance Sensing (ECIS) assay was used to assess EC barrier integrity. Pro-inflammatory signaling markers were measured by western blotting (WB) and qPCR. Cell conditioned media was analyzed for extracellular vesicle release by flow cytometry and WB. Results: MRSA-induced EC barrier disruption was attenuated by both CZ and Ens, although Ens exhibited superior barrier protective properties. CZ and Ens suppressed MRSA-induced upregulation of the inflammatory adhesion molecules, VCAM-1 and ICAM-1, in EC. Ens, but not CZ, reduced MRSA-induced ICAM-1 upregulation in A549. MRSA caused a significant increase in the release of EC-derived extracellular vesicles, which was partially inhibited by CZ or Ens pretreatment. Conclusions: Both cilostazol and ensifentrine exert anti-inflammatory properties in MRSA-treated lung EC. Compared to cilostazol, ensifentrine exhibits enhanced endothelial barrier protection and inhibits inflammation in both lung endothelial and epithelial cells. Future in vivo studies will evaluate the therapeutic efficacy of these inhibitors in bacterial-induced ALI.
Abstract Tu142: Pannexin-2 Deficiency Exacerbates Stress-induced Cell Injury in Cardiomyocytes
Authors: Anusua Sarkar, Seulhee Kim, Lufang Zhou
Journal: Circulation Research (2024)

Pannexins are a family of channel proteins involved in a variety of biological processes, including cell death signaling and immune functions. While Pannexin isoforms 1 and 3 have been widely studied, mainly in the brain, much less is known about the role of isoform 2 (Pannexin2, or Panx2). A recent study showed that deficiency in Panx2 sensitizes pancreatic beta cells to cytokine-induced apoptosis, while another study revealed that Panx2 promotes ultraviolet-induced apoptosis in keratinocytes. The role of Panx2 in the regulation of cardiomyocyte function has not been investigated. In the current study, we explored the subcellular distribution profile of Panx2 expression in cardiomyocytes (AC16 cells and adult cardiomyocytes) and examined the role of Panx2 in regulating cardiomyocyte response to stress. Western blotting analysis revealed palmitoylation of Panx2 in the heart, suggesting that this channel is located intracellularly, instead of in the plasma membrane. Confocal imaging revealed that Panx2 expression is in the proximity of the sarcoplasmic reticulum and mitochondria, confirming its intracellular localization. The stress test results indicated that the knockdown of Panx2 by siRNA exacerbated FCCP-reduced oxidative stress and cell injury in AC16 cells. Similarly, adult cardiomyocytes isolated from Panx2-KO mice were more vulnerable to ischemia-reperfusion injury compared with wild-type cells. Finally, we found that the level of Panx2 expression altered in the cardiac tissue of a mouse model with pressure overload-induced heart failure, implying that Panx2 may be involved in the pathological remodeling of a failing heart.
Abstract Tu034: Endothelial cell regeneration by secretome obtained from P53 silenced bone marrow derived mesenchymal stromal cells (BM-MSCs)
Authors: Seshagiri Rao Nandula, Sabyasachi Sen
Journal: Circulation Research (2024)

Introduction: Diabetes is associated with impaired endothelial function. Studies have demonstrated that endothelial progenitor cells (EPCs) and mature endothelial cells (EC) are susceptible to apoptosis in hyperglycemic environment. Hyperglycemia leads to p53 gene over-expression and p53 gene silencing prior to hyperglycemia exposure prevents cellular senescence, improves mitochondrial function and helps vascular regeneration.. However, it is not possible to obtain sufficient quantities of secretome for therapeutic purposes from hematopoietic CD34+ve stem cells (HSCs). Our goal in this project was to test whether conditioned media (CM) obtained from p53 silenced human stem cells (other than CD34+ve cells) can also improve endothelial regeneration exposed to hyperglycemia. We compared CM obtained from adipose and bone marrow derived mesenchymal stem cells on endothelial regeneration Methods: Ad-human-P53 (TP53)-shRNA was used to silence P53 and Ad-scrambled-null-shRNA was used as control in bone marrow derived mesenchymal stromal cells. To collect conditioned media BM-MSCs were cultured in exosome free FBS media for 5 days, following transduction with Ad-p53sh or Ad-null, as the case may be. After transduction, cells were grown in media containing 2% exosome free FBS for only 48h and the collected supernatant was concentrated 10-fold to obtain the CM. Endothelial regeneration was tested using endothelial wound healing assay kit ( from Cell Biolabs # CBA-120-T). We compared CM obtained from null and p53sh in adipose and bone marrow derived MSCs on human endothelial cells in normal and high glucose conditions Results: We observed that CM from bone marrow derived MSCs increased the proliferation of endothelial cells in both normal and high glucose conditions, more so than adipose derived MSCs. We are currently studying the role of exosomes from this CM on cell proliferation and we are also analyzing the secretome (exosomal and non- exosomal fraction) by mass spectroscopy. Conclusion: P53 silenced BMMSC-CM appears to improve endothelial regeneration in hyperglycemia similar to the effect of p53-silenced HSCs. This maybe secondary to the fact that both these cells are derived from bone marrow and p53 silencing improves mitochondrial function. The CM obtained from BM-MSCs are in sufficient quantities and may have a prominent therapeutic role in treating diabetes vascular complications such as diabetic wound healing.
Abstract Tu139: Ferroptotic Cardiomyocytes Support Angiogenesis in the Infarcted Myocardium
Authors: Rebecca Stairley, Allison Trouten, Shuang Li, Patrick Roddy, Kristine Deleon-Pennell, Henry Sucov, Chun Liu, Ge Tao
Journal: Circulation Research (2024)

Introduction: Mammalian cardiomyocytes have a low turnover rate which is insufficient to repopulate the damaged myocardium after injury caused by myocardial infarction (MI). Previously, we reported that ferroptosis is the main mechanism of cardiomyocyte death in the infarcted neonatal heart. We hypothesized that ferroptotic cardiomyocytes play a beneficial role during the wound healing process. Aims: In this study, we aim to characterize the role of ferroptotic cardiomyocytes by investigating their influence on non-cardiomyocyte populations in the heart post-MI. Methods: Left anterior descending artery occlusion (LAD-O) was performed on wild type (C 5 7BL/6J x FVB) mice at P1. Ferroptosis inhibitor ferrostatin-1 (Fer-1) was delivered at a 2mg/kg dose via subcutaneous injection immediately following LAD-O procedure and again daily until P4. Histology and immunofluorescence were performed to assess myocardial regeneration. iPSC-derived cardiomyocytes (iCMs) were treated with Erastin, Staurosporine, or vehicle control to generate conditioned media. HUVECs were treated with iCM conditioned media for tube formation assays. Results: The infarcts of Fer-1 treated animals show decreased total macrophages from 5.5% to 0.16% (P &lt; 0.05, N = 6 per group, S.E.M. = 1.2%) and those present were less polarized towards the M2 phenotype, decreased from 62.5% to 7.9% (N = 6 per group, P &lt; 0.001, S.E.M. = 9.6%). This trend was confirmed via flow cytometry. The number of Emcn + cells in the infarct was significantly reduced in Fer-1 treated mice, decreasing from 17% to 10% (S.E.M. = 1.7%, N = 4 per group, P &lt; 0.01). HUVECs treated with conditioned media generated by treating iPSC-derived cardiomyocytes with Staurosporine, but not Erastin or DMSO, showed reduced mesh area (fold change from 0.94 to.0 24, N = 5 per group, P &lt; 0.01. S.EM. = .128). Other tube formation endpoints such as extremities, junctions, and branching followed this trend. Conclusions: Our analysis revealed that ferroptotic cardiomyocytes play a supportive role in the wound healing and tissue remodeling environment by directly supporting angiogenesis and polarizing the cardiac macrophages towards a more pro-angiogenic state.
Abstract Tu130: Intracellular Galectin-3 Interacts with Cytosolically Exposed Glycans to Promote the Injury of Cardiomyocytes Under Oxidative Stress
Authors: Chiu-fen Yang, Li-Chen Ho, Jyun-Yu Chiou, Tzu-Ching Meng
Journal: Circulation Research (2024)

Background: Oxidative stress is a hallmark of cardiovascular (CV) diseases. The potential involvement of Galectin-3 (Gal-3) has been proposed in CV pathological conditions, but its role in reactive oxygen species (ROS)-induced cardiomyocyte damage remains elusive. Hypothesis: Oxidative stress leads to ruptures of membrane-bound organelles including lysosome. Intracellular Gal-3 of cardiomyocytes may interact with glycans exposed by ROS-damaged organelles to modulate downstream cellular signaling. Aims: To investigate whether intracellular Gal-3-glycan interactions may occur in ROS-treated cardiomyocytes and how such interactions may regulate cell survival or death. Methods and Results: Using cardiomyoblast H9c2 cells exposed to hydrogen peroxide (H 2 O 2 ) to be the cell model, we found that oxidative stress induced significant lysosomal damage followed by cell death. The immunofluorescence imaging showed that cytosolic Gal-3 aggregated into small puncta, which were colocalized with LAMP2. To examine whether the aggregation of Gal-3 was contributed by ROS-induced damage, catalase was ectopically expressed in H 2 O 2 -treated cells and the formation of Gal-3 puncta was attenuated. These results suggest that intracellular Gal-3 interacts with glycans presented by the ruptured lysosomes in H 2 O 2 -treated H9c2 cells, leading to puncta formation. To further delineate whether these Gal-3 puncta show a functional role in cell survival under oxidative stress, we knocked endogenous Gal-3 down in H9c2 cells by RNAi and found that Gal-3 ablation protected the cells from ROS-induced injuries. Moreover, the ectopic expression of N-terminally truncated Gal-3, which loses its protein-interaction function but preserved the carbohydrate-recognition ability, also prevented H9c2 cells from oxidative stress-caused damage. Conclusions: ROS-induced lysosomal rupture leads to intracellular Gal-3-glycan interactions, further recruiting cytosolic proteins and activating downstream cell death signaling cascades. Such intracellular Gal-3-glycan interactions may contribute to the cardiomyocyte injuries under oxidative stress.
Abstract Tu002: Mesenchymal Stem Cell-Derived Extracellular Vesicles Mitigate Mitochondrial DNA-Induced Activation of Porcine Peripheral Blood Mononuclear Cells
Authors: Sumbule Zahra, Tyler Rolland, Daniel Cucinotta, Brian Weil
Journal: Circulation Research (2024)

Objective: Systemic inflammation is a well-established component of post-cardiac arrest syndrome (PCAS), a condition responsible for significant morbidity and mortality in patients that are initially resuscitated from sudden cardiac arrest. Immune cell activation is pivotal in PCAS pathophysiology, with emerging evidence implicating mitochondrial DNA (mtDNA) as a potent pro-inflammatory stimulus in this context. Given the paucity of available interventions to inhibit mtDNA-induced immune cell activation, we investigated the therapeutic potential of mesenchymal stem cell-derived extracellular vesicles (MSC-EVs) to modulate the inflammatory response of porcine peripheral blood mononuclear cells (PBMCs) activated by mtDNA in vitro . Methods: Porcine bone marrow-derived mesenchymal stem cells (MSCs; P2) were cultured for 5 days and serum-starved for 3 days to collect MSC-EVs. These EVs were isolated from conditioned media (CM) using size exclusion chromatography and ultracentrifugation, then characterized by nanoparticle tracking analysis (ZetaView) and ExoCheck. Naïve PBMCs from healthy swine were cultured for 1 week before stimulation with lipofectamine 2000 (TR-control) or 2 µg/mL mtDNA+TR. MSC-EVs were added to activated PBMCs (2.5e8–2e9 EVs/well) and inflammatory surface marker expression (flow cytometry), inflammatory cytokine transcripts (qPCR) and release (ELISA), and reactive oxygen/nitrogen species (ROS/RNS) production were assessed 24 hours later. Results: mtDNA-stimulated PBMC populations exhibited altered surface marker expression consistent with enrichment of inflammatory granulocytes (CD172+CD163-), macrophages (CD14+CD163+), and adhesion molecules (CD172+) compared to TR-control (all p&lt;0.05). Addition of MSC-EVs significantly reduced the number of all inflammatory cell populations, with the most prominent effects achieved at the highest EV dose (2e9 EVs/well). Likewise, MSC-EVs significantly attenuated mtDNA-activated PBMC expression and secretion of TNFα, IL-1β, and IL-6 ( Figure) and decreased ROS/RNS production in a dose-dependent manner. Conclusion: MSC-EVs attenuate mtDNA-induced activation of PBMCs in a dose-dependent manner, as determined by reductions in pro-inflammatory surface marker expression, inflammatory cytokine gene expression and secretion, and ROS/RNS production. These findings indicate that MSC-EVs may be a viable therapeutic for the inhibition of mtDNA-mediated immune activation in PCAS.
Abstract Tu019: Single-Cell RNA Sequencing Identifies IFNICs as a Cellular Target for Mitigating the Progression of Abdominal Aortic Aneurysm and Rupture Risk
Authors: Sheng Le, Jia Wu, Hao Liu, Yifan Du, Dashuai Wang, Jingjing Luo, Peiwen Yang, Shuan Ran, Poyi Hu, Manhua Chen, Ping Ye, Jiahong Xia
Journal: Circulation Research (2024)

Introduction: Abdominal aortic aneurysm (AAA) represents a life-threatening condition characterized by medial layer degeneration of the abdominal aorta. Nevertheless, knowledge regarding changes in regulators associated with aortic status remains incomplete. A thorough understanding of cell types and signaling pathways involved in the development and progression of AAAs is essential for the development of medical therapy. Methods and Results: We harvested specimens of the abdominal aorta with different pathological features in Angiotensin II (AngII)-infused ApoE -/- mice, conducted scRNA-seq, identified a unique population of interferon-inducible monocytes/macrophages (IFNICs), which were amply found in the abdominal aortic aneurysms (AAAs). Gene set variation analysis (GSVA) revealed that activation of the cytosolic DNA sensing cGAS-STING and JAK-STAT pathways promoted the secretion of type I interferons in monocytes/macrophages and differentiated them into IFNICs. We generated myeloid cell-specific deletion of Sting1 ( Lyz2 -Cre +/- ; Sting1 flox/flox ) mice and performed bone marrow transplantation and found that myeloid cell-specific deletion of Sting1 or Ifnar1 significantly reduced the incidence of AAA, aortic rupture rate and diameter of the abdominal aorta. Mechanistically, the activated pyroptosis- and inflammation-related signaling pathways, regulated by IRF7 in IFNICs, play critical roles in the developing AAAs. Conclusion: IFNICs is a unique monocyte/macrophage subset implicated in the development of AAAs and aortic rupture.