Cathelicidin Antimicrobial Peptide Levels in Atherosclerosis and Myocardial Infarction in Mice and Human.

Obesity represents a worldwide health challenge, and the condition is accompanied by elevated risk of cardiovascular diseases caused by metabolic dysfunction and proinflammatory adipokines. Among those, the immune-modulatory cathelicidin antimicrobial peptide (human: CAMP; murine: CRAMP) might contribute to the interaction of the innate immune system and metabolism in these settings. We investigated systemic CAMP/CRAMP levels in experimental murine models of atherosclerosis, myocardial infarction and cardiovascular patients. Atherosclerosis was induced in low-density lipoprotein receptor-deficient (Ldlr-/-) mice by high-fat diet (HFD). C57BL/6J wild-type mice were subjected to myocardial infarction by permanent or transient left anterior descending (LAD)-ligation. Cramp gene expression in murine organs and tissues was investigated via real-time PCR. Blood samples of 234 adult individuals with or without coronary artery disease (CAD) were collected. Human and murine CAMP/CRAMP serum levels were quantified by ELISA. Atherosclerotic mice exhibited significantly increased CRAMP serum levels and induced Cramp gene expression in the spleen and liver, whereas experimental myocardial infarction substantially decreased CRAMP serum levels. Human CAMP serum quantities were not significantly affected by CAD while being correlated with leukocytes and pro-inflammatory cytokines. Our data show an influence of cathelicidin in experimental atherosclerosis, myocardial infarction, as well as in patients with CAD. Further studies are needed to elucidate the pathophysiological mechanism.

Targeting the High-Density Lipoprotein Proteome for the Treatment of Post-Acute Sequelae of SARS-CoV-2.

Here, we target the high-density lipoprotein (HDL) proteome in a case series of 16 patients with post-COVID-19 symptoms treated with HMG-Co-A reductase inhibitors (statin) plus angiotensin II type 1 receptor blockers (ARBs) for 6 weeks. Patients suffering from persistent symptoms (post-acute sequelae) after serologically confirmed SARS-CoV-2 infection (post-COVID-19 syndrome, PCS, n = 8) or following SARS-CoV-2 vaccination (PVS, n = 8) were included. Asymptomatic subjects with corresponding serological findings served as healthy controls (n = 8/8). HDL was isolated using dextran sulfate precipitation and the HDL proteome of all study participants was analyzed quantitatively by mass spectrometry. Clinical symptoms were assessed using questionnaires before and after therapy. The inflammatory potential of the patients' HDL proteome was addressed in human endothelial cells. The HDL proteome of patients with PCS and PVS showed no significant differences; however, compared to controls, the HDL from PVS/PCS patients displayed significant alterations involving hemoglobin, cytoskeletal proteins (MYL6, TLN1, PARVB, TPM4, FLNA), and amyloid precursor protein. Gene Ontology Biological Process (GOBP) enrichment analysis identified hemostasis, peptidase, and lipoprotein regulation pathways to be involved. Treatment of PVS/PCS patients with statins plus ARBs improved the patients' clinical symptoms. After therapy, three proteins were significantly increased (FAM3C, AT6AP2, ADAM10; FDR < 0.05) in the HDL proteome from patients with PVS/PCS. Exposure of human endothelial cells with the HDL proteome from treated PVS/PCS patients revealed reduced inflammatory cytokine and adhesion molecule expression. Thus, HDL proteome analysis from PVS/PCS patients enables a deeper insight into the underlying disease mechanisms, pointing to significant involvement in metabolic and signaling disturbances. Treatment with statins plus ARBs improved clinical symptoms and reduced the inflammatory potential of the HDL proteome. These observations may guide future therapeutic strategies for PVS/PCS patients.

Heparan Sulfate-Editing Extracellular Sulfatases Enhance VEGF Bioavailability for Ischemic Heart Repair.

RATIONALE: Mechanistic insight into the inflammatory response after acute myocardial infarction may inform new molecularly targeted treatment strategies to prevent chronic heart failure. OBJECTIVE: We identified the sulfatase SULF2 in an in silico secretome analysis in bone marrow cells from patients with acute myocardial infarction and detected increased sulfatase activity in myocardial autopsy samples. SULF2 (Sulf2 in mice) and its isoform SULF1 (Sulf1) act as endosulfatases removing 6-O-sulfate groups from heparan sulfate (HS) in the extracellular space, thus eliminating docking sites for HS-binding proteins. We hypothesized that the Sulfs have a role in tissue repair after myocardial infarction. METHODS AND RESULTS: Both Sulfs were dynamically upregulated after coronary artery ligation in mice, attaining peak expression and activity levels during the first week after injury. Sulf2 was expressed by monocytes and macrophages, Sulf1 by endothelial cells and fibroblasts. Infarct border zone capillarization was impaired, scar size increased, and cardiac dysfunction more pronounced in mice with a genetic deletion of either Sulf1 or Sulf2. Studies in bone marrow-chimeric Sulf-deficient mice and Sulf-deficient cardiac endothelial cells established that inflammatory cell-derived Sulf2 and endothelial cell-autonomous Sulf1 promote angiogenesis. Mechanistically, both Sulfs reduced HS sulfation in the infarcted myocardium, thereby diminishing Vegfa (vascular endothelial growth factor A) interaction with HS. Along this line, both Sulfs rendered infarcted mouse heart explants responsive to the angiogenic effects of HS-binding Vegfa164 but did not modulate the angiogenic effects of non-HS-binding Vegfa120. Treating wild-type mice systemically with the small molecule HS-antagonist surfen (bis-2-methyl-4-amino-quinolyl-6-carbamide, 1 mg/kg/day) for 7 days after myocardial infarction released Vegfa from HS, enhanced infarct border-zone capillarization, and exerted sustained beneficial effects on cardiac function and survival. CONCLUSIONS: These findings establish HS-editing Sulfs as critical inducers of postinfarction angiogenesis and identify HS sulfation as a therapeutic target for ischemic tissue repair.

Deficiency of Nucleotide-binding oligomerization domain-containing proteins (NOD) 1 and 2 reduces atherosclerosis.

Atherosclerosis is crucially fueled by inflammatory pathways including pattern recognition receptor (PRR)-related signaling of the innate immune system. Currently, the impact of the cytoplasmic PRRs nucleotide-binding oligomerization domain-containing protein (NOD) 1 and 2 is incompletely characterized. We, therefore, generated Nod1/Nod2 double knockout mice on a low-density lipoprotein receptor (Ldlr)-deficient background (= Ldlr-/-Nod1/2-/-) which were subsequently analyzed regarding experimental atherosclerosis, lipid metabolism, insulin resistance and gut microbiota composition. Compared to Ldlr-/- mice, Ldlr-/-Nod1/2-/- mice showed reduced plasma lipids and increased hepatic expression of the scavenger receptor LDL receptor-related protein 1 after feeding a high-fat diet for 12 weeks. Furthermore, intestinal cholesterol and its bacterial degradation product coprostanol were elevated in Ldlr-/-Nod1/2-/- mice, correlating with the increased abundance of Eubacterium coprostanoligenes as assessed by 3rd generation sequencing of the gut microbiota. Atherosclerotic plaques of Ldlr-/-Nod1/2-/- mice exhibited less lipid deposition and macrophage accumulation. Moreover, macrophages from Ldlr-/-Nod1/2-/- mice showed higher expression of the cholesterol efflux transporters Abca1 and Abcg1 and accordingly reduced foam cell formation. Deficiency of Nod1 and Nod2 led to reduced plaque lipid deposition and inflammatory cell infiltration in atherosclerotic plaques. This might be explained by diminished plasma lipid levels and foam cell formation due to altered expression of key regulators of the hepatic cholesterol pathway as well as differential intestinal cholesterol metabolism and microbiota composition.

Suppressor of Cytokine Signaling 1 is Involved in Gene Regulation Which Controls the Survival of Ly6Clow Monocytes in Mice.

BACKGROUND/AIMS: Inflammatory processes are controlled by the fine-tuned balance of monocyte subsets. In mice, different subsets of monocytes can be distinguished by the expression of Ly6C that is highly expressed on inflammatory monocytes (Ly6Chigh) and to a lesser extent on patrolling monocytes (Ly6Clow). Our previous study revealed an accumulation of Ly6Chigh monocytes in atherosclerotic-prone mice bearing a deficiency in suppressor of cytokine signaling (SOCS)-1 leading to an increased atherosclerotic burden. To decipher the underlying mechanisms, we performed a genome-wide analysis of SOCS-1-dependent gene regulation in Ly6Chigh and Ly6Clow monocytes. METHODS: In monocyte subsets from SOCS-1competent and -deficient mice differentially regulated genes were identified using an Illumina mRNA microarray (45,200 transcripts), which were randomly validated by qPCR. Principal component analysis was performed to further characterize mRNA profiles in monocyte subsets. To unravel potential regulatory mechanisms behind the differential mRNA expression, in silico analysis of a transcription factor (TF) network correlating with SOCS-1-dependent mRNA expression was carried out and combined with a weighted correlation network analysis (WGCNA). RESULTS: mRNA analysis in monocyte subsets revealed 46 differentially regulated genes by 2-fold or more. Principal component analysis illustrated a distinct separation of mRNA profiles in monocyte subsets from SOCS-1-deficient mice. Notably, two cell surface receptors crucially involved in the determination of monocyte differentiation and survival, C-X3-C chemokine receptor 1 (CX3CR1) and colony stimulating factor 1 receptor (CSF1R), were identified to be regulated by SOCS-1. Moreover, in silico analysis of a TF network in combination with the WGCNA revealed genes coding for PPAR-γ, NUR77 and several ETSdomain proteins that act as pivotal inflammatory regulators. CONCLUSION: Our study reveals that SOCS-1 is implicated in a TF network regulating the expression of central transcription factors like PPAR-γ and NUR77 thereby influencing the expression of CX3CR1 and CSF1R that are known to be pivotal for the survival of Ly6Clow monocytes.

NADPH oxidase NOX2 mediates TLR2/6-dependent release of GM-CSF from endothelial cells.

NADPH oxidase-generated reactive oxygen species (ROS) from immune cells are well known to be important for pathogen killing in response to TLR ligands. Here, we investigated a new aspect of NADPH oxidase in the TLR2/6-induced release of the immunologically relevant GM-CSF by endothelial cells. Stimulation of human endothelial cells with TLR2/6 agonist, MALP-2 (macrophage-activating lipopeptide of 2 kDa), induced NADPH oxidase activation and ROS formation. Inhibition by ROS scavengers and NADPH oxidase inhibitors blocked MALP-2-induced GM-CSF release. NADPH oxidase activators or ROS donors alone did not result in GM-CSF secretion; however, additional superoxide supply augmented MALP-2-induced GM-CSF secretion and restored GM-CSF levels after NADPH oxidase inhibition. MALP-2-dependent NF-ĸB activation was suppressed by NADPH oxidase inhibition, and inhibition of NF-κB completely blunted MALP-2-induced GM-CSF release. Vascular explants from mice that were deficient for the NADPH oxidase subunit p47 phox showed diminished intimal superoxide production and GM-CSF release after ex vivo stimulation with MALP-2. Moreover, an increase in circulating progenitor cells after MALP-2 injection was completely abolished in p47phox-knockout mice. Finally, MALP-2 stimulation increased mRNA expression of the major subunit NADPH oxidase, (Nox)2, in endothelial cells, and Nox2 inhibition prevented MALP-2-induced GM-CSF release. Our findings identify a Nox2-containing NADPH oxidase as a crucial regulator of the immunologic important growth factor GM-CSF after TLR2/6 stimulation in endothelial cells.-Schuett, J., Schuett, H., Oberoi, R., Koch, A.-K., Pretzer, S., Luchtefeld, M., Schieffer, B., Grote, K. NADPH oxidase NOX2 mediates TLR2/6-dependent release of GM-CSF from endothelial cells.

Interleukin-6 receptor inhibition modulates the immune reaction and restores titin phosphorylation in experimental myocarditis.

Increased levels of interleukin-6 (IL-6) have been observed in patients with acute myocarditis and are associated with poor prognosis. This study was designed to examine whether treatment with anti-IL-6 receptor antibody improves cardiac dysfunction and left ventricular (LV) remodeling in experimental Coxsackie virus B3 (CVB3)-induced myocarditis. C57BL6/J mice were subjected to acute CVB3 infection. One day after viral infection mice were treated with a single injection of an anti-IL-6 receptor antibody (MR16-1, tocilizumab) or control IgG. Seven days after viral infection, LV function was examined by conductance catheter technique, cardiac remodeling assessed by estimation of titin phosphorylation, cardiac fibrosis, and inflammatory and antiviral response by immunohistochemistry, RT-PCR and cell culture experiments. Compared to controls, infected mice displayed an impaired systolic and diastolic LV function associated with an increase in cardiac inflammation, fibrosis and impaired titin phosphorylation. IL-6 receptor blockade led to a shift of the immune response to a Th1 direction and significant reduction of viral load. In addition, cardiac immune response, extracellular matrix regulation and titin function improved, resulting in a preserved LV function. IL-6 receptor blockade exerts cardiac beneficial effects by antiviral and immunomodulatory actions after induction of an acute murine CVB3 virus myocarditis.

Toll-like receptor 2/6 agonist macrophage-activating lipopeptide-2 promotes reendothelialization and inhibits neointima formation after vascular injury.

OBJECTIVE: Reendothelialization after vascular injury (ie, balloon angioplasty or stent implantation) is clinically extremely relevant to promote vascular healing. We here investigated the therapeutic potential of the toll-like receptor 2/6 agonist macrophage-activating lipopeptide (MALP)-2 on reendothelialization and neointima formation in a murine model of vascular injury. APPROACH AND RESULTS: The left common carotid artery was electrically injured, and reendothelialization was quantified by Evans blue staining after 3 days. A single injection of MALP-2 (1 or 10 µg, IV) after vascular injury accelerated reendothelialization (P<0.001). Proliferation of endothelial cells at the wound margins determined by 5-ethynyl-2'-deoxyuridine incorporation was significantly higher in MALP-2-treated animals (P<0.05). Furthermore, wire injury-induced neointima formation of the left common carotid artery was completely prevented by a single injection of MALP-2 (10 µg, IV). In vitro, MALP-2 induced proliferation (BrdU incorporation) and closure of an artificial wound of endothelial cells (P<0.05) but not of smooth muscle cells. Protein array and ELISA analysis of isolated primary endothelial cells and ex vivo stimulated carotid segments revealed that MALP-2 stimulated the release of multiple growth factors and cytokines predominantly from endothelial cells. MALP-2 induced a strong activation of the mitogen-activated protein kinase cascade in endothelial cells, which was attenuated in smooth muscle cells. Furthermore, MALP-2 significantly enhanced circulating monocytes and hematopoietic progenitor cells. CONCLUSIONS: The toll-like receptor 2/6 agonist MALP-2 promotes reendothelialization and inhibits neointima formation after experimental vascular injury via enhanced proliferation and migration of endothelial cells. Thus, MALP-2 represents a novel therapeutic option to accelerate reendothelialization after vascular injury.

Decreased circulating CTRP3 levels in acute and chronic cardiovascular patients.

C1q/TNF-related protein 3 (CTRP3) represents an adipokine with various metabolic and immune-regulatory functions. While circulating CTRP3 has been proposed as a potential biomarker for cardiovascular disease (CVD), current data on CTRP3 regarding coronary artery disease (CAD) remains partially contradictory. This study aimed to investigate CTRP3 levels in chronic and acute settings such as chronic coronary syndrome (CCS) and acute coronary syndrome (ACS). A total of 206 patients were classified into three groups: CCS (n = 64), ACS having a first acute event (ACS-1, n = 75), and ACS having a recurrent acute event (ACS-2, n = 67). The control group consisted of 49 healthy individuals. ELISA measurement in peripheral blood revealed decreased CTRP3 levels in all patient groups (p < 0.001) without significant differences between the groups. This effect was exclusively observed in male patients. Females generally exhibited significantly higher CTRP3 plasma levels than males. ROC curve analysis in male patients revealed a valuable predictive potency of plasma CTRP3 in order to identify CAD patients, with a proposed cut-off value of 51.25 ng/mL. The sensitivity and specificity of prediction by CTRP3 were congruent for the subgroups of CCS, ACS-1, and ACS-2 patients. Regulation of circulating CTRP3 levels in murine models of cardiovascular pathophysiology was found to be partly opposite to the clinical findings, with male mice exhibiting higher circulating CTRP3 levels than females. We conclude that circulating CTRP3 levels are decreased in both male CCS and ACS patients. Therefore, CTRP3 might be useful as a biomarker for CAD but not for distinguishing an acute from a chronic setting. KEY MESSAGES: CTRP3 levels were found to be decreased in both male CCS and ACS patients compared to healthy controls. Plasma CTRP3 has a valuable predictive potency in order to identify CAD patients among men and is therefore proposed as a biomarker for CAD but not for distinguishing between acute and chronic settings. Regulation of circulating CTRP3 levels in murine models of cardiovascular pathophysiology was found to be partly opposite to the clinical findings in men.

Signal transducer of inflammation gp130 modulates atherosclerosis in mice and man.

Liver-derived acute phase proteins (APPs) emerged as powerful predictors of cardiovascular disease and cardiovascular events, but their functional role in atherosclerosis remains enigmatic. We report that the gp130 receptor, which is a key component of the inflammatory signaling pathway within hepatocytes, influences the risk of atherosclerosis in a hepatocyte-specific gp130 knockout. Mice on an atherosclerosis-prone genetic background exhibit less aortic atherosclerosis (P < 0.05) with decreased plaque macrophages (P < 0.01). Translating these findings into humans, we show that genetic variation within the human gp130 homologue, interleukin 6 signal transducer (IL6ST), is significantly associated with coronary artery disease (CAD; P < 0.05). We further show a significant association of atherosclerotic disease at the ostium of the coronary arteries (P < 0.005) as a clinically important and heritable subphenotype in a large sample of families with myocardial infarction (MI) and a second independent population-based cohort. Our results reveal a central role of a hepatocyte-specific, gp130-dependent acute phase reaction for plaque development in a murine model of atherosclerosis, and further implicate IL6ST as a genetic susceptibility factor for CAD and MI in humans. Thus, the acute phase reaction should be considered an important target for future drug development in the management of CAD.

Interleukin-1 assembles a proangiogenic signaling module consisting of caveolin-1, tumor necrosis factor receptor-associated factor 6, p38-mitogen-activated protein kinase (MAPK), and MAPK-activated protein kinase 2 in endothelial cells.

OBJECTIVE: Interleukin-1ß (IL-1ß) is a major cytokine linking inflammation and angiogenesis in pathological vascular processes, such as atherosclerosis and tumor neoangiogenesis. However, signaling pathways mediating IL-1ß-induced proangiogenic processes in endothelial cells (ECs) have barely been elucidated yet. Therefore, the present study investigated IL-1ß-induced proangiogenic signaling in ECs. METHODS AND RESULTS: IL-1ß potently induced tube formation and migration of ECs. This was associated with and dependent on activation of p38-mitogen-activated protein kinase (MAPK) and MAPK-activated protein kinase 2 (MK2) as determined by pharmacological inhibition and gene silencing. Furthermore, silencing of the adaptor protein tumor necrosis factor receptor-associated factor 6 (TRAF6) (lentiviral short hairpin RNA) inhibited these IL-1ß-induced processes. Moreover, IL-1ß promoted translocation of TRAF6 to insoluble cellular fractions (containing membrane rafts/caveolae) and interaction of TRAF6 with caveolin-1. Accordingly, cellular cholesterol depletion (cyclodextrin) and silencing of caveolin-1 (small interfering RNA) inhibited IL-1ß-induced activation of p38-MAPK and MK2, as well as IL-1ß-induced tube formation and migration. Finally, silencing of TRAF6 and MK2 deficiency inhibited IL-1ß-induced microvessel outgrowth in murine aortic rings ex vivo, and deficiency of MK2 or caveolin-1 significantly reduced IL-1ß-induced angiogenesis in mice in vivo (Matrigel plug assay). CONCLUSIONS: IL-1ß assembles a proangiogenic signaling module consisting of caveolin-1, TRAF6, p38-MAPK, and MK2 in ECs, representing a potential target to intervene into angiogenesis-dependent processes and diseases.

Transsignaling of interleukin-6 crucially contributes to atherosclerosis in mice.

OBJECTIVE: Transsignaling of interleukin (IL)-6 is a central pathway in the pathogenesis of disorders associated with chronic inflammation, such as Crohn disease, rheumatoid arthritis, and inflammatory colon cancer. Notably, IL-6 also represents an independent risk factor for coronary artery disease (CAD) in humans and is crucially involved in vascular inflammatory processes. METHODS AND RESULTS: In the present study, we showed that treatment with a fusion protein of the natural IL-6 transsignaling inhibitor soluble glycoprotein 130 (sgp130) and IgG1-Fc (sgp130Fc) dramatically reduced atherosclerosis in hypercholesterolemic Ldlr(-/-) mice without affecting weight gain and serum lipid levels. Moreover, sgp130Fc treatment even led to a significant regression of advanced atherosclerosis. Mechanistically, endothelial activation and intimal smooth muscle cell infiltration were decreased in sgp130Fc-treated mice, resulting in a marked reduction of monocyte recruitment and subsequent atherosclerotic plaque progression. Of note, patients with CAD exhibited significantly lower plasma levels of endogenous sgp130, suggesting that a compromised counterbalancing of IL-6 transsignaling may contribute to atherogenesis in humans. CONCLUSIONS: These data clarify, for the first time, the critical involvement of, in particular, the transsignaling of IL-6 in CAD and warrant further investigation of sgp130Fc as a novel therapeutic for the treatment of CAD and related diseases.

Cellular and Systemic Effects of Micro- and Nanoplastics in Mammals-What We Know So Far.

Microplastics (MP) and nanoplastics (NP) are accumulating more and more in our environment and have been frequently detected in water and soil, but also in a variety of mainly marine organisms. Polymers such as polyethylene, polypropylene, and polystyrene are those most commonly found. Once in the environment, MP/NP are carriers for many other substances, which often convey toxic effects. Even though intuitively it is thought that ingesting MP/NP cannot be healthy, little is known about their effects on mammalian cells and organisms so far. To better understand the potential hazards of MP/NP on humans and to offer an overview of the already associated pathological effects, we conducted a comprehensive literature review on cellular effects, as well as experimental animal studies on MP/NP in mammals.

Development of a dual-component infection-resistant arterial replacement for small-caliber reconstructions: A proof-of-concept study.

Introduction: Synthetic vascular grafts perform poorly in small-caliber (<6mm) anastomoses, due to intimal hyperplasia and thrombosis, whereas homografts are associated with limited availability and immunogenicity, and bioprostheses are prone to aneurysmal degeneration and calcification. Infection is another important limitation with vascular grafting. This study developed a dual-component graft for small-caliber reconstructions, comprising a decellularized tibial artery scaffold and an antibiotic-releasing, electrospun polycaprolactone (PCL)/polyethylene glycol (PEG) blend sleeve. Methods: The study investigated the effect of nucleases, as part of the decellularization technique, and two sterilization methods (peracetic acid and γ-irradiation), on the scaffold's biological and biomechanical integrity. It also investigated the effect of different PCL/PEG ratios on the antimicrobial, biological and biomechanical properties of the sleeves. Tibial arteries were decellularized using Triton X-100 and sodium-dodecyl-sulfate. Results: The scaffolds retained the general native histoarchitecture and biomechanics but were depleted of glycosaminoglycans. Sterilization with peracetic acid depleted collagen IV and produced ultrastructural changes in the collagen and elastic fibers. The two PCL/PEG ratios used (150:50 and 100:50) demonstrated differences in the structural, biomechanical and antimicrobial properties of the sleeves. Differences in the antimicrobial activity were also found between sleeves fabricated with antibiotics supplemented in the electrospinning solution, and sleeves soaked in antibiotics. Discussion: The study demonstrated the feasibility of fabricating a dual-component small-caliber graft, comprising a scaffold with sufficient biological and biomechanical functionality, and an electrospun PCL/PEG sleeve with tailored biomechanics and antibiotic release.

Toll-like receptor 2/6 stimulation promotes angiogenesis via GM-CSF as a potential strategy for immune defense and tissue regeneration.

Toll-like receptors (TLRs) are known primarily as pathogen recognition receptors of the innate immunity, initiating inflammatory pathways to organize the immune defense. More recently, an involvement of TLRs in various physiologic and pathologic processes has been reported. Because many of these processes implicate angiogenesis, we here elucidated the role of a TLR2/6-dependent pathway on angiogenesis using the TLR2/6 agonist macrophage-activating lipopeptide of 2 kDa (MALP-2), a common bacterial lipopeptide. In vivo and in vitro Matrigel assays demonstrated that MALP-2 promoted angiogenesis in a TLR2/6-dependent manner. Moreover, MALP-2 induced endothelial cell proliferation and migration and a strong secretion of granulocyte-macrophage colony-stimulating factor (GM-CSF). GM-CSF release in response to MALP-2 from isolated vascular segments was completely prevented when the endothelium was removed. MALP-2 containing Matrigel implants exhibited vascular structures as well as CD45(+) cells. MALP-2 induced migration of leukocytes and likewise GM-CSF release, particularly from the monocyte population. Inhibition of GM-CSF by siRNA or antibodies suppressed MALP-2-induced angiogenesis in vitro and in vivo. These results clearly identified a TLR2/6-dependent induction of angiogenesis by the bacterial lipopeptide MALP-2, which is mediated by GM-CSF. This might represent a general mechanism to enhance or restore blood flow and recruit immune cells for pathogen defense and tissue regeneration.

Extracellular Ribosomal RNA Acts Synergistically with Toll-like Receptor 2 Agonists to Promote Inflammation.

Self-extracellular RNA (eRNA), which is released under pathological conditions from damaged tissue, has recently been identified as a new alarmin and synergistic agent together with toll-like receptor (TLR)2 ligands to induce proinflammatory activities of immune cells. In this study, a detailed investigation of these interactions is reported. The macrophage cell line J774 A.1 or C57 BL/6 J wild-type mice were treated with 18S rRNA and different TLR2 agonists. Gene and protein expression of tumor necrosis factor (Tnf)-α; interleukin (Il)-1ß, Il-6; or monocyte chemoattractant protein (Mcp)-1 were analyzed and furthermore in vitro binding studies to TLR2 were performed. The TLR2/TLR6-agonist Pam2 CSK4 (Pam2) together with 18S rRNA significantly increased the mRNA expression of inflammatory genes and the release of TNF-α from macrophages in a TLR2- and nuclear factor kappa B (NF-κB)-dependent manner. The injection of 18S rRNA/Pam2 into mice increased the cytokine levels of TNF-α, IL-6, and MCP-1 in the peritoneal lavage. Mechanistically, 18S rRNA built complexes with Pam2 and thus enhanced the affinity of Pam2 to TLR2. These results indicate that the alarmin eRNA, mainly consisting of rRNA, sensitizes TLR2 to enhance the innate immune response under pathological conditions. Thus, rRNA might serve as a new target for the treatments of bacterial and viral infections.

Monocyte subpopulation profiling indicates CDK6-derived cell differentiation and identifies subpopulation-specific miRNA expression sets in acute and stable coronary artery disease.

Coronary artery disease (CAD) is a long-lasting inflammatory disease characterized by monocyte migration into the vessel wall leading to clinical events like myocardial infarction (MI). However, the role of monocyte subsets, especially their miRNA-driven differentiation in this scenario is still in its infancy. Here, we characterized monocyte subsets in controls and disease phenotypes of CAD and MI patients using flow cytometry and miRNA and mRNA expression profiling using RNA sequencing. We observed major differences in the miRNA profiles between the classical (CD14++CD16-) and nonclassical (CD14+CD16++) monocyte subsets irrespective of the disease phenotype suggesting the Cyclin-dependent Kinase 6 (CDK6) to be an important player in monocyte maturation. Between control and MI patients, we found a set of miRNAs to be differentially expressed in the nonclassical monocytes and targeting CCND2 (Cyclin D2) that is able to enhance myocardial repair. Interestingly, miRNAs as miR-125b playing a role in vascular calcification were differentially expressed in the classical subset in patients suffering from CAD and not MI in comparison to control samples. In conclusion, our study describes specific peculiarities of monocyte subset miRNA expression in control and diseased samples and provides basis to further functional analysis and to identify new cardiovascular disease treatment targets.

Case Report: Arterial Wall Inflammation in Atherosclerotic Cardiovascular Disease is Reduced by Olamkicept (sgp130Fc).

Inflammation is a strong driver of atherosclerotic cardiovascular disease (ASCVD). There is a large unmet need for therapies that prevent or reduce excessive inflammation while avoiding systemic immunosuppression. We showed previously that selective inhibition of pro-inflammatory interleukin-6 (IL-6) trans-signalling by the fusion protein olamkicept (sgp130Fc) prevented and reduced experimental murine atherosclerosis in low-density lipoprotein receptor-deficient (Ldlr -/-) mice on a high-fat, high-cholesterol diet independently of low-density lipoprotein (LDL) cholesterol metabolism. Therefore, we allowed compassionate use of olamkicept (600 mg intravenously biweekly for 10 weeks) in a patient with very-high-risk ASCVD. Despite optimal LDL cholesterol under maximum tolerated lipid-lowering treatment, the patient had a remaining very high risk for future cardiovascular events related to significant arterial wall inflammation with lipoprotein (a) [Lp(a)]-cholesterol as the main contributor. 18Fluorodeoxyglucose positron emission tomography/computed tomography (18FDG PET/CT) measurements were performed before and after the treatment period. Olamkicept reduced arterial wall inflammation in this patient without interfering with lipoprotein metabolism. No clinical or laboratory side effects were observed during or after treatment with olamkicept. Our findings in this patient matched the results from our mechanistic study in Ldlr -/- mice, which were extended by additional analyses on vascular inflammation. Olamkicept may be a promising option for treating ASCVD independently of LDL cholesterol metabolism. A Phase II trial of olamkicept in ASCVD is currently being prepared.

Chemokine receptor 7 knockout attenuates atherosclerotic plaque development.

BACKGROUND: Atherosclerosis is a systemic inflammatory disease characterized by the formation of atherosclerotic plaques. Both innate immunity and adaptive immunity contribute to atherogenesis, but the mode of interaction is poorly understood. Chemokine receptor 7 (CCR7) is critically involved in the transition from innate to adaptive immune activation by coordinating the migration to and positioning of antigen-presenting dendritic cells and T cells in secondary lymphoid organs. More recently, it was shown that CCR7 is also responsible for T-cell migration into inflamed tissues and T-cell egress from these tissues via the afferent lymph. Thus, we investigated the influence of a systemic CCR7 deficiency on atherogenesis in atherosclerosis-prone low-density lipoprotein receptor (ldlr) knockout mice. METHODS AND RESULTS: CCR7 deficiency resulted in reduced atherosclerotic plaque development. CCR7(-/-) T cells showed impaired entry and exit behavior from atherosclerotic lesions. Oxidized low-density lipoprotein, a key molecule for atherogenesis with antigenic features, was used to pulse dendritic cells and to expand T cells ex vivo. Adoptive transfer of C57BL/6 wild-type T cells but not ccr7(-/-)-derived T cells primed with oxidized low-density lipoprotein-pulsed dendritic cells resulted in a reconstitution of atherogenesis in ccr7(-/-)/ldlr(-/-) mice. CONCLUSION: These results demonstrate that both CCR7-dependent T-cell priming in secondary lymphoid organs and CCR7-dependent recirculation of T cells between secondary lymphoid organs and inflamed tissue are crucially involved in atherosclerotic plaque development.

ADAMTS13--marker of contractile phenotype of arterial smooth muscle cells lost in benign nephrosclerosis.

BACKGROUND: Hypertensive nephrosclerosis alone and in combination with other renal diseases is a leading cause of terminal renal insufficiency. Histologic lesions manifest as benign nephrosclerosis (bN) with arteriolar hyalinosis and later fibrosis. Procoagulant micromilieus have been implicated in fibrosis. Hyalinosis is considered to consist of plasma insudation possibly containing procoagulant factors like von Willebrand factor (VWF). Therefore, it is hypothesized that VWF cleaving protease ADAMTS13 (a disintegrin-like and metalloprotease with thrombospondin type-1 motif, 13) is normally expressed by arteriolar vascular smooth muscle cells (VSMCs) and diminished in bN and that this reduction contributes to fibrosis in bN. METHODS: ADAMTS13 expression was examined by immunohistochemistry and quantitative real-time polymerase chain reaction in VSMCs of various human organs. Fifty-four specimens with and seven without bN were immunostained for ADAMTS13, VWF, CD61 and VSMC differentiation markers in arteriolar walls. RESULTS: Expression of ADAMTS13 is confirmed in VSMCs. In bN, ADAMTS13 immunostaining of arterial VSMCs correlated inversely with fibrotic but not hyalinotic lesions. Smooth muscle myosin heavy chain showed an inverse correlation with hyalinotic, as opposed to fibrotic lesions of bN. Smoothelin showed an inverse correlation with both hyalinotic and fibrotic lesions of bN. VWF was absent in normal controls and hyalinotic lesions, but present exclusively in fibrotic lesions in 7/54 (13%) bN cases. CD61 was absent in all arteriolar walls. CONCLUSIONS: The present results establish ADAMTS13 as a novel marker of contractile VSMCs that is retained in early hyalinotic bN but partially lost later in fibrotic bN. Loss of ADAMTS13 and accumulation of VWF in fibrotic but not hyalinotic arteriolar walls could further propagate fibrosis in bN.