Biology subjects

Hofer, L.

Publications and source records attributed to Hofer, L..

3 recordsLinked to original sources

bioRxiv2025

Large extracellular vesicles derived from red blood cells in coronary artery disease patients with anemia promote endothelial dysfunction

Background and purposeEndothelial dysfunction (ED) is a hallmark of cardiovascular disease (CVD). We recently showed that anemia is associated with worsening of endothelial function after acute myocardial infarction (AMI). Extracellular vesicles (EVs) are efficient communicators between cells and can functionally contribute to different CVD, including, AMI. However, their specific role of EVs in stable coronary artery disease (CAD)-associated with anemia, particularly their contribution to ED, has not yet been investigated systematically. Experimental approachRed blood cell-derived EVs (REVs) and plasma-derived EVs (PLEVs) from all blood cells and endothelium were isolated from patients with stable CAD. The isolated large REVs and PLEVs were characterized using dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), and Western blotting. Uptake assays were performed by co-incubating with fluorescently-labeled REVs and PLEVs with human umbilical vein endothelial cells (ECs). Nitric oxide (NO) consumption ability of REVs was analyzed using a chemiluminescence detector (CLD). After co-incubation of aortic rings explanted from wild-type (WT) mice with REVs and PLEVs from anemic and non-anemic CAD patients, endothelial function was assessed using a wire myograph system. To investigate differences in the content of REVs and PLEVs between anemic and non-anemic CAD patients, proteomic analysis was performed. Key resultsDLS analysis showed that both REVs and PLEVs were within the size distribution range of 100-1000 nm. NTA analysis revealed increased release of REVs in anemic patients compared to non-anemic patients. Co-incubation of labeled REVs and PLEVs with ECs demonstrated their uptake by ECs in vitro which was similar between anemic patients compared to non-anemic patients. REVs from anemic patients showed increased NO consumption compared to those from non-anemic patients. Aortic rings co-incubated with REVs from anemic patients showed attenuated endothelial NO-dependent relaxation responses compared to non-anemic patients. Proteomics analysis of REVs from anemic patients revealed numerous differentially expressed proteins, including decreased abundance of antioxidant proteins such as catalase 1 (CAT1), superoxide dismutase 1 (SOD1) and increased oxidative stress-promoting myeloperoxidase (MPO). Co-incubation of ECs with REVs from anemic patients demonstrated increased ROS production. ConclusionAnemia is associated with increased release of REVs and enhanced NO consumption, which promotes ED. This is further exacerbated by an altered redox balance and increased ROS production, implicating therapeutic importance in anemic patients with CAD. Graphical AbstractAnemia is associated with an increased release of RBC-derived large extracellular vesicles (REVs), which are taken up by endothelial cells (ECs). Anemic REVs show enhanced nitric oxide (NO) consumption, contributing to NO dysregulation in ECs. Additionally, REVs carry various redox enzymes, including the oxidative stress-promoting enzyme myeloperoxidase (MPO), as well as antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT). An imbalance in these redox enzymes leads to increased oxidative stress and endothelial nitric oxide synthase (eNOS) uncoupling, resulting in impaired NO-mediated relaxation responses and subsequent endothelial dysfunction (ED). O_FIG O_LINKSMALLFIG WIDTH=166 HEIGHT=200 SRC="FIGDIR/small/642191v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@19d4cccorg.highwire.dtl.DTLVardef@1d1b3forg.highwire.dtl.DTLVardef@e7f144org.highwire.dtl.DTLVardef@190b007_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2024

Distinct effects of acute and chronic blood loss anemia on vascular function after acute myocardial infarction

BackgroundAnemia is frequently observed in patients with cardiovascular diseases (CVD). Anemia alone or in combination with other morbid conditions leads to poor prognosis in acute myocardial infarction (AMI). We recently showed that moderate blood loss anemia is associated with red blood cell (RBC) dysfunction and a compensatory increase in flow-mediated dilation (FMD) responses which are compromised in chronic blood loss anemia However, the effects of acute anemia (AA) and chronic anemia (CA) on endothelial function after AMI are unclear. In this study, we evaluated systemic endothelial function following AMI in established murine models of blood loss acute and chronic anemia. We hypothesize that both AA and CA aggravate systemic endothelial dysfunction (ED) after AMI. Methods and resultsAA or CA was induced in male C57BL/6J mice by repeated blood withdrawal for three consecutive days or six weeks, respectively. Separate groups of anemic and non-anemic mice underwent AMI via left anterior descending artery (LAD) ligation (45 min), followed by reperfusion. Endothelial function was assessed using both in vivo and in vitro methods 24 h post-AMI. Impaired flow-mediated dilation (FMD, in vivo) and endothelium-dependent relaxation (EDR) responses were observed in the aorta, femoral, and saphenous arteries of AA mice compared to their respective control groups 24 h post AMI. The aorta and saphenous arteries from CA mice showed significantly reduced vascular smooth muscle (VSM) contractile responses after AMI. Analysis of oxidative products of nitric oxide (NO) in plasma revealed reduced nitrite and nitrate levels in both AA and CA mice compared to controls 24 h post-AMI. Immunohistochemistry of aortic tissues from both anemic groups showed increased reactive oxygen species (ROS) product 4-Hydroxynonenal (4-HNE). Co-incubation of RBCs from anemic mice or anemic ST-elevation myocardial infarction (STEMI) patients with aortic rings from wild type mice demonstrated attenuated VSM contractile and EDR responses. Supplementation with the ROS scavenger N-acetyl cysteine (NAC) for four weeks improved both in vivo and ex vivo EDR in AA and CA mice 24 h post-AMI. ConclusionAfter AMI, both AA and CA are associated with severe ED, while VSM contractile responses specifically reduced in CA mice. These effects are accompanied by increased ROS and partly mediated by RBCs. Antioxidant supplementation with NAC is a potential therapeutic option to reverse the severe vascular dysfunction in anemia following AMI. Graphical AbstractDistinct effects of acute and chronic anemia on vascular function 24 h post-AMI. After acute myocardial infarction, acute and chronic anemia are associated with increased reactive oxygen species (ROS) and inflammation in endothelial cells (EC), leading to the inhibition of endothelial nitric oxide synthase (eNOS) and subsequent endothelial dysfunction by limiting NO bioavailability. Chronic anemia is additionally associated with decreased vascular smooth muscle cell (VSMC) function due to increased oxidative stress, leading to SMC dysfunction. After N-Acetyl-L-Cysteine (NAC) treatment, vascular function is improved in both anemic groups. O_FIG O_LINKSMALLFIG WIDTH=98 HEIGHT=200 SRC="FIGDIR/small/614629v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@136583aorg.highwire.dtl.DTLVardef@da8708org.highwire.dtl.DTLVardef@d73539org.highwire.dtl.DTLVardef@e7516a_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2024

Silybin A from Silybum marianum reprograms lipid metabolism to induce a cell fate-dependent class switch from triglycerides to phospholipids

Silybum marianum is used to protect against degenerative liver damage. The molecular mechanisms of its bioactive component, silybin, remained enigmatic, although membrane-stabilizing properties, modulation of membrane protein function, and metabolic regulation have been discussed for decades. Here, we show that specifically the stereoisomer silybin A decreases triglyceride levels and lipid droplet content, while enriching major phospholipid classes and maintaining a homeostatic phospholipid composition in human hepatocytes in vitro and in mouse liver in vivo under normal and pre-disease conditions. Conversely, in cell-based disease models of lipid overload and lipotoxic stress, silybin treatment primarily depletes triglycerides. Mechanistically, silymarin/silybin suppresses phospholipid-degrading enzymes, induces phospholipid biosynthesis to varying degrees depending on the conditions, and down-regulates triglyceride biosynthesis, while inducing complex changes in sterol and fatty acid metabolism. Structure-activity relationship studies highlight the importance of the 1,4-benzodioxane ring configuration of silybin A in triglyceride reduction and the saturated 2,3-bond of the flavanonol moiety in phospholipid accumulation. Enrichment of hepatic phospholipids and intracellular membrane expansion are associated with an heightened biotransformation capacity. In conclusion, our study deciphers the structural features of silybin contributing to hepatic lipid reorganization and offers insights into its liver-protective mechanism, potentially involving a context-dependent lipid class switch from triglycerides to phospholipids.

pharmacology and toxicology↗