Peripheral priming induces plastic transcriptomic and proteomic responses in circulating neutrophils required for pathogen containment.

Neutrophils rapidly respond to inflammation and infection, but to which degree their functional trajectories after mobilization from the bone marrow are shaped within the circulation remains vague. Experimental limitations have so far hampered neutrophil research in human disease. Here, using innovative fixation and single-cell-based toolsets, we profile human and murine neutrophil transcriptomes and proteomes during steady state and bacterial infection. We find that peripheral priming of circulating neutrophils leads to dynamic shifts dominated by conserved up-regulation of antimicrobial genes across neutrophil substates, facilitating pathogen containment. We show the TLR4/NF-κB signaling-dependent up-regulation of canonical neutrophil activation markers like CD177/NB-1 during acute inflammation, resulting in functional shifts in vivo. Blocking de novo RNA synthesis in circulating neutrophils abrogates these plastic shifts and prevents the adaptation of antibacterial neutrophil programs by up-regulation of distinct effector molecules upon infection. These data underline transcriptional plasticity as a relevant mechanism of functional neutrophil reprogramming during acute infection to foster bacterial containment within the circulation.

Longitudinal In Vivo Monitoring of Atheroprogression in Hypercholesterolemic Mice Using Photoacoustic Imaging.

BACKGROUND AND AIM: The ability to recognize and monitor atherosclerotic lesion development using noninvasive imaging is crucial in preventive cardiology. The aim of the present study was to establish a protocol for longitudinal monitoring of plaque lipid, collagen, and macrophage burden as well as of endothelial permeability. METHODS AND RESULTS: Photoacoustic signals derived from endogenous or exogenous dyes assessed in vivo, in plaques of albino Apoe -/- mice, correlated with lesion characteristics obtained after histomorphometric and immunofluorescence analyses, thus supporting the validity of our protocol. Using models of atheroprogression and regression, we could apply our imaging protocol to the longitudinal observation of atherosclerotic lesion characteristics in mice. CONCLUSIONS: The present study shows an innovative approach to assess arterial inflammation in a non-invasive fashion, applicable to longitudinal analyses of changes of atherosclerotic lesion composition. Such approach could prove important in the preclinical testing of therapeutic interventions in mice carrying pre-established lesions.

Design, synthesis, and biological evaluation of novel pyrrolidinone small-molecule Formyl peptide receptor 2 agonists.

A series of Formyl peptide receptor 2 small molecule agonists with a pyrrolidinone scaffold, derived from a combination of pharmacophore modelling and docking studies, were designed and synthesized. The GLASS (GPCR-Ligand Association) database was screened using a pharmacophore model. The most promising novel ligand structures were chosen and then tested in cellular assays (calcium mobilization and ß-arrestin assays). Amongst the selected ligands, two pyrrolidinone compounds (7 and 8) turned out to be the most active. Moreover compound 7 was able to reduce the number of adherent neutrophils in a human neutrophil static adhesion assay which indicates its anti-inflammatory and proresolving properties. Further exploration and optimization of new ligands showed that heterocyclic rings, e.g. pyrazole directly connected to the pyrrolidinone scaffold, provide good stability and a boost in the agonistic activity. The compounds of most interest (7 and 30) were tested in an ERK phosphorylation assay, demonstrating selectivity towards FPR2 over FPR1. Compound 7 was examined in an in vivo mouse pharmacokinetic study. Compound 7 may be a valuable in vivo tool and help improve understanding of the role of the FPR2 receptor in the resolution of inflammation process.

Agrin Promotes Coordinated Therapeutic Processes Leading to Improved Cardiac Repair in Pigs.

BACKGROUND: Ischemic heart diseases are leading causes of death and reduced life quality worldwide. Although revascularization strategies significantly reduce mortality after acute myocardial infarction (MI), a large number of patients with MI develop chronic heart failure over time. We previously reported that a fragment of the extracellular matrix protein agrin promotes cardiac regeneration after MI in adult mice. METHODS: To test the therapeutic potential of agrin in a preclinical porcine model, we performed ischemia-reperfusion injuries using balloon occlusion for 60 minutes followed by a 3-, 7-, or 28-day reperfusion period. RESULTS: We demonstrated that local (antegrade) delivery of recombinant human agrin to the infarcted pig heart can target the affected regions in an efficient and clinically relevant manner. A single dose of recombinant human agrin improved heart function, infarct size, fibrosis, and adverse remodeling parameters 28 days after MI. Short-term MI experiments along with complementary murine studies revealed myocardial protection, improved angiogenesis, inflammatory suppression, and cell cycle reentry as agrin's mechanisms of action. CONCLUSIONS: A single dose of agrin is capable of reducing ischemia-reperfusion injury and improving heart function, demonstrating that agrin could serve as a therapy for patients with acute MI and potentially heart failure.

Telmisartan cardioprotects from the ischaemic/hypoxic damage through a miR-1-dependent pathway.

The aim of this study was to investigate whether telmisartan protects the heart from the ischaemia/reperfusion damage through a local microRNA-1 modulation. Studies on the myocardial ischaemia/reperfusion injury in vivo and on the cardiomyocyte hypoxia/reoxygenation damage in vitro were done. In vivo, male Sprague-Dawley rats administered for 3 weeks with telmisartan 12 mg/kg/d by gastric gavage underwent ischaemia/reperfusion of the left descending coronary artery. In these rats, infarct size measurement, ELISA, immunohistochemistry (IHC) and reverse transcriptase real-time polymerase chain reaction showed that expressions of connexin 43, potassium voltage-gated channel subfamily Q member 1 and the protein Bcl-2 were significantly increased by telmisartan in the reperfused myocardium, paralleled by microRNA-1 down-regulation. In vitro, the transfection of cardiomyocytes with microRNA-1 reduced the expressions of connexin 43, potassium voltage-gated channel subfamily Q member 1 and Bcl-2 in the cells. Telmisartan (50 µmol/L) 60 minutes before hypoxia/reoxygenation, while not affecting the levels of miR-1 in transfected cells in normoxic condition, almost abolished the increment of miR-1 induced by the hypoxia/reoxygenation to transfected cells. All together, telmisartan cardioprotected against the myocardial damage through the microRNA-1 modulation, and consequent modifications of its downstream target connexin 43, potassium voltage-gated channel subfamily Q member 1 and Bcl-2.

Pro-Angiogenic Macrophage Phenotype to Promote Myocardial Repair.

BACKGROUND: Heart failure following myocardial infarction (MI) remains one of the major causes of death worldwide, and its treatment is a crucial challenge of cardiovascular medicine. An attractive therapeutic strategy is to stimulate endogenous mechanisms of myocardial regeneration. OBJECTIVES: This study evaluates the potential therapeutic treatment with annexin A1 (AnxA1) to induce cardiac repair after MI. METHODS: AnxA1 knockout (AnxA1-/-) and wild-type mice underwent MI induced by ligation of the left anterior descending coronary artery. Cardiac functionality was assessed by longitudinal echocardiographic measurements. Histological, fluorescence-activated cell sorting, dot blot analysis, and in vitro/ex vivo studies were used to assess the myocardial neovascularization, macrophage content, and activity in response to AnxA1. RESULTS: AnxA1-/- mice showed a reduced cardiac functionality and an expansion of proinflammatory macrophages in the ischemic area. Cardiac macrophages from AnxA1-/- mice exhibited a dramatically reduced ability to release the proangiogenic mediator vascular endothelial growth factor (VEGF)-A. However, AnxA1 treatment enhanced VEGF-A release from cardiac macrophages, and its delivery in vivo markedly improved cardiac performance. The positive effect of AnxA1 treatment on cardiac performance was abolished in wild-type mice transplanted with bone marrow derived from Cx3cr1creERT2Vegfflox/flox or in mice depleted of macrophages. Similarly, cardioprotective effects of AnxA1 were obtained in pigs in which full-length AnxA1 was overexpressed by use of a cardiotropic adeno-associated virus. CONCLUSIONS: AnxA1 has a direct action on cardiac macrophage polarization toward a pro-angiogenic, reparative phenotype. AnxA1 stimulated cardiac macrophages to release high amounts of VEGF-A, thus inducing neovascularization and cardiac repair.

Addition of the Aldose Reductase Inhibitor Benzofuroxane Derivative BF-5m to Prolonged and Moderate Exercise Training Enhanced Protection of the Rat Heart From Type-1 Diabetes.

Moderate exercise training may not be sufficient to exert beneficial effects on the cardiovascular system because of the long-term multifactorial etiology of diabetic complications. The addition of a proper pharmacological tool to the physical exercise should improve the outcomes of the diabetic damage. Here it is shown that 8 weeks exercise training of type 1 diabetic Sprague-Dawley (SD) rats resulted in a significantly increased heart rate, a 14% increase in the left ventricular ejection fraction (LVEF) increased plasma insulin levels and a 13% decrease in plasma glucose with respect to sedentary animals. The training also resulted in a 22% reduction in cardiac QT interval from a diabetic sedentary value of 185 ± 19 ms. Treatment of trained rats with the new antioxidant and NO-releasing aldose reductase 2 inhibitor 5(6)-(benzo[d]thiazol-2-ylmethoxy) benzofuroxane BF-5m, 20 mg/kg/day, added a further and significant (P < 0.01 vs. sedentary) increase of the LVEF up to 38% at 8 week time point. The long QT interval recorded in trained rats was reduced to further 12% by addition to the training of pharmacological treatment with 20 mg/kg/day BF-5m. At this time, the association of the two treatments improved the expression into the cardiac tissue of sarcoplasmic reticulum Ca2+ ATPase 2 (SERCA2) and manganese superoxide dismutase (MnSOD), and reduced the fibrosis.

Ly6Chigh Monocytes Oscillate in the Heart During Homeostasis and After Myocardial Infarction-Brief Report.

OBJECTIVE: Circadian regulation of neutrophil homeostasis affects myocardial infarction (MI) healing. It is unknown whether diurnal variations of monocyte counts exist in the heart and whether this affects their cardiac infiltration in response to MI. APPROACH AND RESULTS: Murine blood and organs were harvested at distinct times of day and analyzed by flow cytometry. Ly6Chigh monocyte surface expression levels of chemokine receptors (CCR) were ≈2-fold higher at the beginning of the active phase, Zeitgeber Time (ZT) 13 compared with ZT5. This was because of enhanced receptor surface expression at ZT13, whereas no significant changes in total cellular protein levels were found. Most blood Ly6Chigh monocytes were CCR2high, whereas only a minority was CCR1high and CCR5high. We also found diurnal changes of classical monocyte blood counts in humans, being higher in the evening, while exhibiting enhanced CCR2 surface expression in the morning. In support of monocyte oscillations between blood and tissue, murine cardiac Ly6Chigh monocyte counts were highest at ZT13, accompanied by an upregulation of cardiac CC chemokine ligand 2 mRNA. Mice subjected to MI at ZT13 had an even higher upregulation of CCR2 surface expression on circulating monocytes compared with noninfarcted mice and more elevated cardiac CC chemokine ligand 2 protein expression and more pronounced Ly6Chigh monocyte infiltration compared with ZT5-infarcted mice. Concomitantly, CCR2 antagonism only inhibited the excessive cardiac Ly6Chigh monocyte infiltration after ZT13 MI but not ZT5 MI. CONCLUSIONS: CCR2 surface expression on Ly6Chigh monocytes changes in a time-of-day-dependent manner, which crucially affects cardiac monocyte recruitment after an acute ischemic event.

Protective Aptitude of Annexin A1 in Arterial Neointima Formation in Atherosclerosis-Prone Mice-Brief Report.

OBJECTIVE: Restenosis as a consequence of arterial injury is aggravated by inflammatory pathways. Here, we investigate the role of the proresolving protein annexin A1 (AnxA1) in healing after wire injury. APPROACH AND RESULTS: Apoe-/- and Apoe-/-Anxa1-/- mice were subjected to wire injury while fed a high-cholesterol diet. Subsequently, localization of AnxA1 and AnxA1 plasma levels were examined. AnxA1 was found to localize within endothelial cells and macrophages in the neointima. Levels of AnxA1 in the plasma and its lesional expression negatively correlated with neointima size, and in the absence of AnxA1, neointima formation was aggravated by the accumulation and proliferation of macrophages. In contrast, reendothelialization and smooth muscle cell infiltration were not affected in Apoe-/-Anxa1-/- mice. CONCLUSIONS: AnxA1 is protective in healing after wire injury and could, therefore, be an attractive therapeutic compound to prevent from restenosis after vascular damage.

Recruitment of classical monocytes can be inhibited by disturbing heteromers of neutrophil HNP1 and platelet CCL5.

In acute and chronic inflammation, neutrophils and platelets, both of which promote monocyte recruitment, are often activated simultaneously. We investigated how secretory products of neutrophils and platelets synergize to enhance the recruitment of monocytes. We found that neutrophil-borne human neutrophil peptide 1 (HNP1, α-defensin) and platelet-derived CCL5 form heteromers. These heteromers stimulate monocyte adhesion through CCR5 ligation. We further determined structural features of HNP1-CCL5 heteromers and designed a stable peptide that could disturb proinflammatory HNP1-CCL5 interactions. This peptide attenuated monocyte and macrophage recruitment in a mouse model of myocardial infarction. These results establish the in vivo relevance of heteromers formed between proteins released from neutrophils and platelets and show the potential of targeting heteromer formation to resolve acute or chronic inflammation.