Biology subjects

Pfeiler, S.

Publications and source records attributed to Pfeiler, S..

6 recordsLinked to original sources

bioRxiv2024

Novel fluorescence-based methods to determine infarct and scar size in murine models of reperfused myocardial infarction

BackgroundDetermination of infarct area and scar size following myocardial infarction (MI) is commonly used to evaluate the efficacy of potential cardioprotective treatments in mice and other animal models. MethodsFor both, early and late time points following MI, we compared classical histochemical approaches with fluorescence staining methods. Reperfused MI was induced in male C57BL/6J mice and hearts were extracted 24 hours, 7-, 21-, or 28-days following MI and stained with 2,3,5-Triphenyltetrazolium chloride (TTC) and Evans Blue, Hoechst, phalloidin, Sirius Red, Massons or Gomoris Trichrome or Wheat Germ Agglutinin (WGA). ResultsFluorescent staining combining Hoechst and phalloidin constitutes an alternative for TTC and Evans Blue, enabling a clear visualization of infarct area, area at risk, as well as remote area unaffected by MI. Infarct size early after reperfusion determined with TTC staining correlates strongly with that demarcated by phalloidin while combination of Hoechst and phalloidin staining can emulate classical TTC/Evans Blue staining 24 h post-MI. Moreover, WGA is equally accurate as the classical Sirius Red, Massons and Gomoris Trichrome stainings in identifying scar size in later phases (>7d) post-MI. Finally, we demonstrate feasibility of combining conventional fluorescence staining by localizing CD45+ leukocytes to specific regions of the infarcted myocardium. ConclusionWe established staining procedure is not inferior to classical TTC staining while providing substantial benefits including the option for unbiased software-assisted analysis while sparing ample residual tissue for additional analyses. Overall, this enhances the data quality and reduces the required animal numbers consistent with the 3R concept of animal experimentation. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=131 SRC="FIGDIR/small/604384v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@17ccc83org.highwire.dtl.DTLVardef@56d433org.highwire.dtl.DTLVardef@857f37org.highwire.dtl.DTLVardef@63297d_HPS_FORMAT_FIGEXP M_FIG C_FIG

pathology↗

bioRxiv2024

Crosstalk between thrombospondin-1 and CD36 modulates platelet-RBC interaction limiting thrombosis and abdominal aneurysm formation

Red blood cells (RBCs) contribute to hemostasis and thrombosis by interaction with platelets via the FasL-FasR pathway to induce procoagulant activity and thrombin formation. Here, we identified a novel mechanism of platelet-RBC interaction via the CD36-thrombospondin-1 (TSP-1) signaling pathway, which is important in thrombus formation and the recruitment of RBCs to collagen-adherent platelets. Platelet-released TSP-1 can bind to CD36 at the RBC membrane to enhance procoagulant activity and to increase the activation of integrin IIb{beta}3, which represents an additional ligand for erythroid FasR, suggesting that both mechanisms of platelet-RBC interaction act in concert to propagate thrombus formation. In patients with abdominal aortic aneurysm (AAA), enhanced procoagulant activity of RBCs and platelets is accompanied by elevated exposure of TSP-1 and FasL at the platelet surface and accumulation of TSP-1 in the aortic wall and the intraluminal thrombus, suggesting that platelet-RBC interaction plays an important role in AAA pathology. TSP-1-deficient mice are protected against aortic diameter expansion in an experimental model of AAA, highlighting the crucial role of the CD36-TSP-1 axis in AAA. Thus, interfering with platelet-RBC interaction may be a promising therapeutic approach to reduce pro-coagulant activity and preserve AAA patients from surgery or rupture.

pathology↗

bioRxiv2023

Inhibition of CD40-TRAF6 signaling protects against aneurysm development and progression

ObjectiveInflammation is a critical process during the progressive development and complication of abdominal aortic aneurysm. The co-stimulatory dyad CD40-CD40L is a major driver of inflammation and modulates immune responses. This study evaluates the potential of a small molecule inhibitor, which blocks the interaction between CD40 and tumor necrosis factor (TNF) receptor-associated factor (TRAF)-6, referred to as TRAF-STOP, in the early and later phase during AAA progression. Methods and resultsAAAs were induced in C57BL/6J mice by infrarenal aortic porcine pancreatic elastase infusion for 7, 14 or 28 days. Inhibition of CD40 signaling by TRAF-STOP resulted in less severe AAA formation and reduced the incidence of AAA development. TRAF-STOP treatment attenuated aortic structural remodeling, characterized by a reduced elastic fiber degradation, lowered expression of matrix metalloproteinase (MMP)-2 and MMP9, as well as preserved collagen type IV content in aneurysmal tissue. Furthermore, this is accompanied by the reduction of key pro-inflammatory genes such as TNF. ConclusionPharmacological inhibition of CD40-TRAF6 signaling protects from adverse aortic structural remodeling during the early phase of AAA progression representing a translational strategy to limit progression of human AAA disease.

pharmacology and toxicology↗

bioRxiv2022

Using TCR and BCR sequencing to unravel the role of T and B cells in abdominal aortic aneurysm

BackgroundAbdominal aortic aneurysm (AAA) is a life-threatening cardiovascular disease, and the pathogenesis is still poorly understood. Recent evidence suggests that AAA displays characteristics of an autoimmune disease and it gained increasing prominence that specific antigen-driven T cells in the aortic tissue may contribute to the initial immune response. Single-cell RNA T- and B cell receptor (TCR and BCR) sequencing is a powerful tool to investigate TCR and BCR clonality and thus to further test this hypothesis. However, difficulties such as very limited numbers of isolated cells must be considered during implementation and data analysis making biological interpretation of the data challenging. Here, we perform a representative analysis of scRNA TCR and BCR sequencing data of experimental murine AAA and show a reliable and streamlined bioinformatic processing pipeline highlighting opportunities and limitations of this approach. MethodsWe performed single-cell RNA TCR and BCR sequencing of isolated lymphocytes from the infrarenal aortic segment of male C57BL/6J mice 3, 7, 14, and 28 days after AAA induction via elastase perfusion of the aorta. Sham operated mice at day 3 and 28 as well as non-operated mice served as controls. ResultsComparison of complementarity-determining region (CDR3) length distribution of 179 B cells and 796 T cells revealed no differences between AAA and control nor between the disease stages. We found no clonal expansion of B cells in AAA. For T cells, we identified multiple clones in 11 of 16 AAA samples and in 1 of 8 control samples. Comparison of the immune receptor repertoires indicated that only few clones were shared between the individual AAA samples. The most frequently used V-genes in the TCR beta chain in AAA were TRBV3, TRBV19, and TRBV12-2+TRBV13-2. ConclusionIn summary, we found no clonal expansion of TCRs or BCRs in elastase-induced AAA in mice. Our findings imply that a more precise characterization of TCR and BCR distribution requires a more extensive amount of T and B cells to prevent undersampling and to enable detection of potential rare clones. Using this current scSeq-based approach we did not identify clonal enrichment of T or B cells in experimental AAA.

immunology↗

bioRxiv2022

Quantitative assessment of angioplasty induced vascular inflammation with 19F cardiovascular magnetic resonance imaging

Early macrophage rich vascular inflammation is a key feature in the pathophysiology of restenosis after angioplasty. 19F MRI with intravenously applied perfluorooctyl bromide-nanoemulsion (PFOB-NE) could offer ideal features for serial imaging of the inflammatory response after angioplasty. We aimed to non-invasively image monocyte/macrophage infiltration in response to angioplasty in pig carotid arteries using Fluorine-19 magnetic resonance imaging (19F MRI) to assess early inflammatory response to mechanical injury. Early macrophage rich vascular inflammation is a key feature in the pathophysiology of restenosis after angioplasty. 19F MRI with intravenously applied perfluorooctyl bromide-nanoemulsion (PFOB-NE) could offer ideal features for serial imaging of the inflammatory response after angioplasty. In eight minipigs, injury of the right carotid artery was induced by either balloon oversize angioplasty only (BA, n=4) or in combination with endothelial denudation (BA + ECDN, n=4). PFOB-NE was administered intravenously three days after injury followed by 1H and 19F MRI to assess vascular inflammatory burden at day six. Vascular response to mechanical injury was validated using immunohistology. Angioplasty was successfully induced in all eight pigs. Response to injury was characterized by positive remodeling with predominantly adventitial wall thickening and adventitial infiltration of monocytes/macrophages. 19F signal could be detected in vivo in four pigs following BA + ECDN with a robust signal-to-noise ratio (SNR) of 14.7 {+/-} 4.8. Ex vivo analysis revealed a linear correlation of 19F SNR to local monocyte/macrophage cell density. Minimum detection limit of infiltrated monocytes/macrophages was as about 400 cells/mm2. Therefore, 19F MRI enables quantification of monocyte/macrophage infiltration after vascular injury with sufficient sensitivity. This might open an avenue to non-invasively monitor inflammatory response to mechanical injury after angioplasty and thus to identify individuals with distinct patterns of vascular inflammation promoting restenosis. One Sentence Summary19F MRI enables radiation-free quantification of monocyte/macrophage infiltration after vascular injury with sufficient sensitivity.

immunology↗

bioRxiv2022

Inhibition of myeloperoxidase prevents thoracic aortic aneurysm formation in Marfan mice

Marfan syndrome (MFS) is the most prevalent inherited connective tissue disorder, still remains uncurable, and is characterized by high mortality at early age driven by dissection and rupture of thoracic aortic aneurysms. MFS is caused by mutations in the fibrillin-1 gene and aberrant TGF{beta} signaling. Here we addressed whether myeloperoxidase (MPO), a leukocyte derived enzyme with potent matrix modulating properties also influences the aortic phenotype in MFS. MFS patients displayed increased circulating MPO levels compared to controls as well as marked aortic MPO deposition. In an MFS mouse model, MPO induced inflammatory endothelial activation and endothelial to mesenchymal transition which triggered aortic leukocyte recruitment. Moreover, MPO directly contributed to adverse extracellular matrix remodeling by promoting oxidative stress and nitration of proteins within the vascular wall. Genetic MPO deficiency and pharmacological MPO inhibition attenuated MFS-related aneurysm formation. We herein identify MPO as a critical mediator of MFS-related thoracic aortic aneurysm formation and - in the absence of any pharmacological treatment so far in this disease - a first anti-inflammatory target to modulate disease progression.

immunology↗