Pharmacological targeting of the hyper-inflammatory response to SARS-CoV-2-infected K18-hACE2 mice using a cluster of differentiation 36 receptor modulator.

The scientific and medical community faced an unprecedented global health hazard that led to nearly 7 million deaths attributable to the rapid spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In spite of the development of efficient vaccines against SARS-CoV-2, many people remain at risk of developing severe symptoms as the virus continues to spread without beneficial patient therapy. The hyper-inflammatory response to SARS-CoV-2 infection progressing to acute respiratory distress syndrome remains an unmet medical need for improving patient care. The viral infection stimulates alveolar macrophages to adopt an inflammatory phenotype regulated, at least in part, by the cluster of differentiation 36 receptor (CD36) to produce unrestrained inflammatory cytokine secretions. We suggest herein that the modulation of the macrophage response using the synthetic CD36 ligand hexarelin offers potential as therapy for halting respiratory failure in SARS-CoV-2-infected patients.

A cyclic azapeptide ligand of the scavenger receptor CD36/SR-B2 reduces the atherosclerotic lesion progression and enhances plaque stability in apolipoprotein E-deficient mice.

Atherosclerosis is a chronic inflammatory disease of the arterial walls that develops at predisposed sites. As a major risk factor for adverse cardiovascular pathology, atherosclerosis can progress to myocardial infarction and stroke, due to the rupture of unstable atherosclerotic lesions. Macrophage uptake of modified lipoproteins and metabolic dysfunction contributes significantly to the initiation and development of atherosclerotic lesions. The cluster of differentiation 36 receptor [CD36 (SR-B2)] plays a key role in atherosclerotic lesion progression and acts as an efferocytic molecule in the resolution of advanced plaque. In previous studies, linear azapeptide CD36 ligands were shown to exhibit anti-atherosclerotic properties. In the present study, a novel potent and selective macrocyclic azapeptide CD36 ligand, MPE-298, has proven effective in protecting against atherosclerosis progression. Features of greater plaque stability were observed after 8 weeks of daily injections with the cyclic azapeptide in apolipoprotein E-deficient mice fed a high-fat high-cholesterol diet.

Therapeutic applications of nanoparticles targeting neutrophil and extracellular traps.

Neutrophils, the most abundant leukocytes in human circulation, are key effectors and regulators of both innate and adaptive immunity which migrate from the bloodstream to sites of inflammation or infection in response to different stimuli. A growing body of evidence has revealed that dysregulated neutrophil activity contributes to the development of several diseases. Targeting their function has been proposed as a potential strategy to treat or mitigate the progression of these disorders. Additionally, neutrophil tropism has been proposed as a strategy to drive therapeutic agents towards targeted disease sites. In this article, we review the proposed nanomedicine approaches to target neutrophils and their components, the regulation of their function and the use of their tropism in drug delivery for therapeutic purposes.

Optimization of a Liposomal DNase I Formulation with an Extended Circulating Half-Life.

Drug delivery systems such as liposomes are widely used to stabilize and increase the plasma half-life of therapeutics. In this article, we have investigated two strategies to increase the half-life of deoxyribonuclease I, an FDA-approved enzyme used for the treatment of cystic fibrosis, and a potential candidate for the reduction of uncontrolled inflammation induced by neutrophil extracellular traps. We demonstrate that our optimized preparation procedure resulted in nanoparticles with improved plasma half-life and total exposure relative to native protein, while maintaining enzymatic activity.

Tailoring PEGylated nanoparticle surface modulates inflammatory response in vascular endothelial cells.

Polymer nanoparticles (NPs) are extensively studied as drug delivery systems for various therapeutic indications, including drug and imaging agent delivery to the brain. Despite intensive research, their toxicological profile has yet to be fully characterized. In particular, the more subtle effects of nanomaterials on inflammatory processes have scarcely been investigated. Surface properties of NPs are amongst parameters governing interactions between living cells and NPs. They could considerably influence the toxicity and inflammatory response of the cells exposed to NPs. Polymeric NPs investigated here present a core-shell structure. The core is constituted of hydrophobic poly(lactic acid) (PLA) block and the surface is composed of a shell of hydrophilic block of polyethylene glycol (PEG). The effect of PEG chain length coating on the expression of genes involved in the inflammation response was investigated in two vascular endothelial cell lines (bEnd.3 and HUVEC) by qPCR. Moreover, ROS generation following NP uptake was evaluated. PEGylated NPs induce a mild and transient activation of inflammatory cytokine and chemokine genes. However, differences in PEG chain length did not show any significant effect on cytokine and chemokine gene expression and PEGylated NPs did not trigger ROS generation. The present results could contribute significantly to a deeper understanding of nanomaterial interactions and toxicity with vascular endothelial cells, guiding scientists in material coating choices.

A quantitative UHPLC-MS/MS method for the growth hormone-releasing peptide-6 determination in complex biological matrices and transdermal formulations.

Growth hormone-releasing peptide-6 (GHRP-6) is part of a group of small synthetic peptides with potent GH-releasing activity that have gained attention in the last two decades by virtue of their cyto- and cardioprotective effects. Despite numerous preclinical studies highlighting the potential cardiovascular benefits of GHRP-6, confirmation of clinical efficacy is still awaited. Recent advances in transdermal drug delivery systems have been made to address challenges related to the poor skin permeation rate of peptides by using pain-free microneedle (MN) devices. Accordingly, highly sensitive and validated analytical methods are required for the potential clinical translation of MN-based peptides. The ultra-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) methods developed in this study aimed to quantify GHRP-6 in biological matrices (plasma, skin) and dissolving polymeric MNs. UHPLC/MS-MS method detection limits of 0.1, 1.1, 0.9 and 1.5 ng/mL were achieved in neat solution, plasma, MN polymer solution, and skin matrices, respectively. Method validation also involved assessment of precision, accuracy, limits of quantification, linearity of matched calibration curves (R2 > 0.990), extraction recovery, matrix effect, stability studies, selectivity, and carry-over effect. Additionally, quality control samples were analyzed at three concentration levels to determine recovery (85-109%) and accuracy/bias (3.2-14.7%). Intra- and inter-day precision were within the range of acceptance (RSDs of 3.0-13.9% and 0.4-14.5%, respectively). The validity and applicability of such methods were successfully demonstrated for transdermal GHRP-6 delivery using GHRP-6-loaded MN patches applied to pig skin.

Ex vivo Ikkß ablation rescues the immunopotency of mesenchymal stromal cells from diabetics with advanced atherosclerosis.

AIMS: Diabetes is a conventional risk factor for atherosclerotic cardiovascular disease and myocardial infarction (MI) is the most common cause of death among these patients. Mesenchymal stromal cells (MSCs) in patients with type 2 diabetes mellitus (T2DM) and atherosclerosis have impaired ability to suppress activated T-cells (i.e. reduced immunopotency). This is mediated by an inflammatory shift in MSC-secreted soluble factors (i.e. pro-inflammatory secretome) and can contribute to the reduced therapeutic effects of autologous T2DM and atherosclerosis-MSC post-MI. The signalling pathways driving the altered secretome of atherosclerosis- and T2DM-MSC are unknown. Specifically, the effect of IκB kinase ß (IKKß) modulation, a key regulator of inflammatory responses, on the immunopotency of MSCs from T2DM patients with advanced atherosclerosis has not been studied. METHODS AND RESULTS: MSCs were isolated from adipose tissue obtained from patients with (i) atherosclerosis and T2DM (atherosclerosis+T2DM MSCs, n = 17) and (ii) atherosclerosis without T2DM (atherosclerosis MSCs, n = 17). MSCs from atherosclerosis+T2DM individuals displayed an inflammatory senescent phenotype and constitutively expressed active forms of effectors of the canonical IKKß nuclear factor-κB transcription factors inflammatory pathway. Importantly, this constitutive pro-inflammatory IKKß signature resulted in an altered secretome and impaired in vitro immunopotency and in vivo healing capacity in an acute MI model. Notably, treatment with a selective IKKß inhibitor or IKKß knockdown (KD) (clustered regularly interspaced short palindromic repeats/Cas9-mediated IKKß KD) in atherosclerosis+T2DM MSCs reduced the production of pro-inflammatory secretome, increased survival, and rescued their immunopotency both in vitro and in vivo. CONCLUSIONS: Constitutively active IKKß reduces the immunopotency of atherosclerosis+T2DM MSC by changing their secretome composition. Modulation of IKKß in atherosclerosis+T2DM MSCs enhances their myocardial repair ability.

Atheroprotective and atheroregressive potential of azapeptide derivatives of GHRP-6 as selective CD36 ligands in apolipoprotein E-deficient mice.

BACKGROUND AND AIMS: Scavenger receptor class B member 3, also known as cluster of differentiation-36 (CD36) receptor, is involved in the uptake and accumulation of modified lipoprotein in macrophages, driving atherosclerosis progression. Azapeptide analogs of growth hormone-releasing peptide-6 (GHRP-6) have been developed as selective CD36 ligands and evaluated for their anti-atherosclerotic properties in apoe-/- mice. METHODS: From 4 to 19 weeks of age, male apoe-/- mice were fed a high fat high cholesterol (HFHC) diet, then switched to normal chow and treated daily with 300 nmol/kg of MPE-001 ([aza-Tyr4]-GHRP-6) or MPE-003 ([aza-(N,N-diallylaminobut-2-ynyl)Gly4]-GHRP-6) for 9 weeks. In another protocol, mice were fed a HFHC diet throughout the study. RESULTS: Azapeptides decreased lesion progression in the aortic arch and reduced aortic sinus lesion areas below pre-existing lesions levels in apoe-/- mice which were switched to chow diet. In mice fed a HFHC throughout the study, azapeptides reduced lesion progression in the aortic vessel and sinus. The anti-atherosclerotic effect of azapeptides was associated with a reduced ratio of iNOS+/CD206+ macrophages within lesions, and lowered plasma inflammatory cytokine levels. Monocytes from azapeptide-treated mice showed altered mitochondrial oxygen consumption rates, consistent with an M2-like phenotype. These effects were dependent on CD36, and not observed in apoe-/-cd36-/- mice. CONCLUSIONS: Azapeptides MPE-001 and MPE-003 diminished aortic lesion progression and reduced, below pre-existing levels, lesions in the aortic sinus of atherosclerotic mice. A relative increase of M2-like macrophages was observed in lesions, associated with reduced systemic inflammation. Development of CD36-selective azapeptide ligands merits consideration for treating atherosclerotic disease.

Immunometabolic modulation of retinal inflammation by CD36 ligand.

In subretinal inflammation, activated mononuclear phagocytes (MP) play a key role in the progression of retinopathies. Little is known about the mechanism involved in the loss of photoreceptors leading to vision impairment. Studying retinal damage induced by photo-oxidative stress, we observed that cluster of differentiation 36 (CD36)-deficient mice featured less subretinal MP accumulation and attenuated photoreceptor degeneration. Moreover, treatment with a CD36-selective azapeptide ligand (MPE-001) reduced subretinal activated MP accumulation in wild type mice and preserved photoreceptor layers and function as assessed by electroretinography in a CD36-dependent manner. The azapeptide modulated the transcriptome of subretinal activated MP by reducing pro-inflammatory markers. In isolated MP, MPE-001 induced dissociation of the CD36-Toll-like receptor 2 (TLR2) oligomeric complex, decreasing nuclear factor-kappa B (NF-κB) and NLR family pyrin domain containing 3 (NLRP3) inflammasome activation. In addition, MPE-001 caused an aerobic metabolic shift in activated MP, involving peroxisome proliferator-activated receptor-γ (PPAR-γ) activation, which in turn mitigated inflammation. Accordingly, PPAR-γ inhibition blocked the cytoprotective effect of MPE-001 on photoreceptor apoptosis elicited by activated MP. By altering activated MP metabolism, MPE-001 decreased immune responses to alleviate subsequent inflammation-dependent neuronal injury characteristic of various vision-threatening retinal disorders.

EP80317 Restrains Inflammation and Mortality Caused by Scorpion Envenomation in Mice.

Over 1 million cases of scorpion stings are estimated every year, whereas current treatment is limited to antivenom serum combined with supportive therapy. Tityus serrulatus scorpion venom (TsV) is composed of diverse molecules, including toxins that induce a catecholamine storm and mediate classical symptoms of scorpion envenomation. However, the same toxins promote an intense inflammatory response coordinated by innate immune cells, such as macrophages, contributing significantly to the lung edema and mortality caused by TsV injection. Macrophages sense TsV via innate immune receptors, including TLR2, TLR4, and CD14 that promote inflammation and mortality via PGE2/cAMP/PKA/NF-κB/IL-1ß axis. The scavenger receptor CD36 also recognizes TsV, but in contrast to the other receptors, it drives the production of leukotriene B4 (LTB4). This lipid mediator operates via BLT1 receptor to reduce cAMP production and consequently IL-1ß release, which results in resistance to fatal outcomes of experimental scorpion envenomation. EP80317 is an hexapeptide that serves as a ligand for CD36 and features protective effects under conditions such as atherosclerosis and vascular inflammation. In this study, we evaluated the effects of EP80317 treatment during experimental scorpion envenomation. EP80317 treatment suppressed mouse peritoneal macrophage production of IL-1ß, IL-6, tumor necrosis factor (TNF-α), CCL3, and PGE2 in vitro. EP80317 treatment also boosted the production of LTB4 and IL-10 in response to TsV. Importantly, EP80317 restrained lung inflammation and mortality caused by TsV in vivo. Taken together, these data indicate a strong therapeutic potential of EP80317 as a supportive treatment to control inflammation induced by scorpion envenomation.

A Linear Fragment of Unacylated Ghrelin (UAG6-13) Protects Against Myocardial Ischemia/Reperfusion Injury in Mice in a Growth Hormone Secretagogue Receptor-Independent Manner.

Unacylated ghrelin (UAG), the most abundant form of ghrelin in circulation, has been shown to exert cardioprotective effect in experimental cardiopathies. The present study aimed to investigate the cardioprotective effect of a linear bioactive fragment of UAG against myocardial ischemia-induced injury and dysfunction in C57BL/6 wild type mice and the mechanisms involved. Treatments were administered at doses of 100 (UAG), 1,000 and 3,000 (UAG6-13) nmol/kg at 12 h interval during 14 days prior to 30 min left coronary artery ligation and reperfusion for a period of 6 or 48 h. The infarct area was decreased in a dose-dependent manner at 48 h of reperfusion, with a reduction of 54% at the highest dose of UAG6-13 tested. Myocardial hemodynamics were improved as demonstrated by an increase in cardiac output, maximum first derivative of left ventricular pressure, and preload recruitable stroke work, a load-independent contractility index. Six hours after reperfusion, circulating levels of IL-6 and TNF-α pro-inflammatory cytokines were reduced, and the effect was maintained at 48 h for TNF-α. 5' AMP-activated protein kinase (AMPK) was activated, while acetyl-CoA carboxylase (ACC) activity was inhibited, along with a decrease in apoptotic protein levels. In isolated hearts, the effect of UAG6-13 was unaffected by the presence of D-Lys3-GHRP-6, a ghrelin receptor (GHSR1a) antagonist, suggesting that the peptide acted through a GHSR1a-independent pathway. The results support the therapeutic application of UAG bioactive peptide fragments against myocardial ischemia/reperfusion injury.

Adiponectin has a pivotal role in the cardioprotective effect of CP-3(iv), a selective CD36 azapeptide ligand, after transient coronary artery occlusion in mice.

CD36 is a multiligand receptor involved in lipid metabolism. We investigated the mechanisms underlying the cardioprotective effect of CP-3(iv), an azapeptide belonging to a new class of selective CD36 ligands. The role of CP-3(iv) in mediating cardioprotection was investigated because CD36 signaling leads to activation of peroxisome proliferator-activated receptor-γ, a transcriptional regulator of adiponectin. CP-3(iv) pretreatment reduced infarct size by 54% and preserved hemodynamics in C57BL/6 mice subjected to 30 min coronary ligation and reperfusion but had no effect in CD36-deficient mice. The effects of CP-3(iv) were associated with an increase in circulating adiponectin levels, epididymal fat adiponectin gene expression, and adiponectin transcriptional regulators ( Pparg, Cebpb, Sirt1) after 6 h of reperfusion. Reduced myocardial oxidative stress and apoptosis were observed along with an increase in expression of myocardial adiponectin target proteins, including cyclooxygenase-2, phospho-AMPK, and phospho-Akt. Moreover, CP-3(iv) increased myocardial performance in isolated hearts, whereas blockade of adiponectin with an anti-adiponectin antibody abrogated it. CP-3(iv) exerts cardioprotection against myocardial ischemia and reperfusion (MI/R) injury and dysfunction, at least in part, by increasing circulating and myocardial adiponectin levels. Hence, both paracrine and endocrine effects of adiponectin may contribute to reduced reactive oxygen species generation and apoptosis after MI/R, in a CD36-dependent manner.-Huynh, D. N., Bessi, V. L., Ménard, L., Piquereau, J., Proulx, C., Febbraio, M., Lubell, W. D., Carpentier, A. C., Burelle, Y., Ong, H., Marleau, S. Adiponectin has a pivotal role in the cardioprotective effect of CP-3(iv), a selective CD36 azapeptide ligand, after transient coronary artery occlusion in mice.

Atheroregressive Potential of the Treatment with a Chimeric Monoclonal Antibody against Sulfated Glycosaminoglycans on Pre-existing Lesions in Apolipoprotein E-Deficient Mice.

The retention of lipoprotein particles in the intima, in particular to glycosaminoglycan side chains of proteoglycans, is a critical step in atherosclerosis initiation. Administration of chP3R99, a chimeric mouse/human monoclonal antibody inducing an anti-idiotypic network response against glycosaminoglycans was previously shown to prevent atherosclerotic lesion progression, yet its effect in the late-stage progression of lesions remains unknown. This study investigated the effect of chP3R99 at a late stage of disease development in apolipoprotein E-deficient mice and the vascular mechanisms involved. Male apolipoprotein E-deficient mice were fed a high-fat high-cholesterol diet from 4 to 19 weeks old, at which time mice were fed normal chow and 5 doses of chP3R99 (50 µg) or isotype-matched IgG (hR3) were administered subcutaneously weekly for the first 3 administrations, then at weeks 24 and 26 before sacrifice (week 28). Lesions progression was reduced by 88% in treated mice with no change in total plasma cholesterol levels, yet with increased sera reactivity to chP3R99 idiotype and heparin, suggesting the induction of an anti-idiotype antibody cascade against glycosaminoglycans, which was likely related with the atheroprotective effect. chP3R99 treatment initiated regression in a significant number of mice. Circulating levels of interleukin-6 were reduced along with a striking diminution of inflammatory cell accumulation in the vessel wall, and of VCAM-1 labeling in vivo. The ratio of IL-10/iNOS gene expression in aortas increased in chP3R99-treated mice. In conclusion, our results show that treatment with chP3R99 reduces vascular inflammatory burden and halts lesion progression with potential for regression in the late phase of the disease in atherosclerotic mice, and support the therapeutic intervention against glycosaminoglycans as a novel strategy to reverse atherosclerosis.

Dose-Dependent Induction of an Idiotypic Cascade by Anti-Glycosaminoglycan Monoclonal Antibody in apoE-/- Mice: Association with Atheroprotection.

Atherosclerosis, the underlying pathology of most cardiovascular diseases, is triggered by the retention of apolipoprotein B (apoB)-containing lipoproteins in the arterial wall through electrostatic interactions with glycosaminoglycan (GAG) side chains of proteoglycans. Previously, we reported the antiatherogenic properties of the chimeric monoclonal antibody (mAb) chP3R99-LALA, which binds sulfated GAGs, inhibits low-density lipoprotein (LDL)-chondroitin sulfate (CS) association, and abrogates LDL oxidation and foam cell formation. In preventive and therapeutic settings, apoE-deficient (apoE-/-) mice immunized with 50 µg of this mAb showed reduced atherosclerotic lesions related with the induction of autologous anti-GAG antibodies. Knowing that age and sex are major non-modifiable risk factors in the development of atherosclerosis, the present study aimed to assess the influence of these variables on the capacity of chP3R99-LALA mAb to generate an anti-CS antibody response. Also, we aimed at defining the impact of the dose of chP3R99-LALA on the anti-CS antibody induction and the atheroprotective effect of this mAb in apoE-/- mice. Neither age nor sex had an impact in the IgG anti-CS antibody response induced by s.c. immunization with this mAb. Moreover, chP3R99-LALA mAb reduced atherosclerotic lesions to a similar extent in both young male and female apoE-/- mice fed a hypercholesterolemic diet and, in middle-aged female apoE-/- mice, with spontaneous lesions. On the other hand, increasing the dose of chP3R99-LALA (200 vs. 50 µg) elicited an anti-idiotype antibody cascade characterized by higher levels of anti-idiotype (Ab2), anti-anti-idiotype (Ab3), and anti-CS antibody responses. Moreover, this dose increment resulted in a striking reduction of aortic atherosclerotic lesions in immunized mice.

Arresting progressive atherosclerosis by immunization with an anti-glycosaminoglycan monoclonal antibody in apolipoprotein E-deficient mice.

Atherogenesis is associated with the early retention of low-density lipoproteins (LDL) in the arterial intima by interaction with glycosaminoglycan (GAG)-side chains of proteoglycans. Retained LDL undergo reactive oxygen species-mediated oxidation. Oxidized LDL trigger oxidative stress (OS) and inflammation, contributing to atherosclerosis development. Recently, we reported the preventive anti-atherogenic properties of the chimeric mouse/human monoclonal antibody (mAb) chP3R99-LALA, which were related to the induction of anti-chondroitin sulfate antibody response able to inhibit chondroitin sulfate dependent LDL-enhanced oxidation. In the present work, we aimed at further investigating the impact of chP3R99-LALA mAb vaccination on progressive atherosclerosis in apolipoprotein E-deficient mice (apoE(-/-)) fed with a high-fat high-cholesterol diet receiving 5 doses (50 µg) of the antibody subcutaneously, when ~5% of the aortic area was covered by lesions. Therapeutic immunization with chP3R99-LALA mAb halted atherosclerotic lesions progression. In addition, aortic OS was modulated, as shown by a significant (p<0.05) reduction of lipid and protein oxidation, preservation of antioxidant enzymes activity and reduced glutathione, together with a decrease of nitric oxide levels. chP3R99-LALA mAb immunization also regulated aortic NF-κB activation, diminishing the proinflammatory IL1-ß and TNF-α gene expression as well as the infiltration of macrophages into the arterial wall. The therapeutic immunization of apoE(-/-) with progressive atheromas and persistent hypercholesterolemia using chP3R99-LALA mAb arrested further development of lesions, accompanied by a decrease of aortic OS and NF-κB-regulated pro-inflammatory cytokine gene expression. These results contribute to broaden the potential use of this anti-GAG antibody-based immunotherapy as a novel approach to target atherosclerosis at different phases of progression.

QRFP-43 inhibits lipolysis by preventing ligand-induced complex formation between perilipin A, caveolin-1, the catalytic subunit of protein kinase and hormone-sensitive lipase in 3T3-L1 adipocytes.

QRFP (RFamide) peptides are neuropeptides involved in food intake and adiposity regulation in rodents. We have previously shown that QRFP-43 (43RFa) and QRFP-26 (26RFa) inhibited isoproterenol (ISO)-induced lipolysis in adipocytes. However, the antilipolytic signaling pathways activated by QRFP peptides have not been investigated. In the present study, 3T3-L1 adipocytes were used to identify the main pathways involved in QRFP-43 decreasing ISO-induced lipolysis. Our results show that QRFP-43 reduced ISO-induced phosphorylation of perilipin A (PLIN) and hormone-sensitive lipase (HSL) on Ser660 by 43 and 25%, respectively, but increased Akt phosphorylation by 44%. However, the inhibition of phosphodiesterase 3B (PDE3B), a regulator of lipolysis activated by Akt, did not reverse the antilipolytic effect of QRFP-43. PDE3B inhibition reversed the decrease of Ser660 HSL phosphorylation associated with QRFP-43 antilipolytic effect. QRFP-43 also prevented PKC activation and ISO-induced Src kinases activation leading to the inhibition of the caveolin-1 (CAV-1) translocation on lipid droplets. Indeed, QRFP-43 attenuated phorbol 12-myristate 13-acetate-induced lipolysis and ISO-induced extracellular signal-regulated and Src kinases by 28, 37 and 48%, respectively. The attenuation of ISO-induced lipolysis by QRFP-43 was associated with a decrease of phosphorylated Ser660 HSL, PKA-catalytic (PKA-c) subunit and CAV-1 translocation on lipid droplets by 37, 50 and 46%, respectively. The decrease in ISO-induced CAV-1 and PKA-c translocation was associated with a reduction of PLIN phosphorylation by 44% in QRFP-43-treated adipocytes. These results suggest that QRFP-43 attenuated ISO-induced lipolysis by preventing the formation of an active complex on lipid droplets and the activation of Src kinases and PKC.

Impairment of neutrophil migration to remote inflammatory site during lung histoplasmosis.

Histoplasma capsulatum (Hc) induces a pulmonary disease in which leukotrienes promote activation and recruitment of effectors cells. It is also well-recognized that leukotriene B4 (LTB4) and platelet-activating factor (PAF) induce leukocyte recruitment to inflammatory sites. We investigated the impact of pulmonary Hc infection on PMN migration to a remote inflammatory site. Our results show that pulmonary Hc infection impairs LTB4- or PAF-stimulated PMN recruitment to air pouch. Yet, remote inflammation did not modify PMN numbers in the bronchoalveolar lavage fluid (BALF) of Hc-infected mice. Interestingly, the concomitant administration of PAF and LTB4 receptor antagonists inhibited PMN recruitment to both BALF and the remote site, demonstrating cooperation between both mediators. Along that line, our results show that PAF-elicited PMN chemotaxis was abrogated in 5-lipoxygenase-deficient animals. These results suggest caution in the indiscriminate use of anti-inflammatory drugs during infectious diseases.

Potential peptides in atherosclerosis therapy.

Atherosclerosis is the main underlying cause of ischemic heart disease and related acute cardiovascular complications, including myocardial infarction and stroke. In view of the failure of statins to demonstrate a beneficial effect in all patients, exhaustive research efforts have unfold into different research avenues, in close relation to the increase in basic knowledge regarding lipoprotein metabolism, macrophage function and inflammatory conditions associated with atherosclerosis. This review focuses specifically on potential therapeutic peptides targeting dyslipidemia, macrophage scavenger receptors, cholesterol metabolism and anti-inflammatory cytokines as novel therapeutic avenues in atherosclerosis.

Pyroglutamylated RF-amide peptide (QRFP) gene is regulated by metabolic endotoxemia.

Pyroglutamylated RF-amide peptide (QRFP) is involved in the regulation of food intake, thermogenesis, adipogenesis, and lipolysis. The expression of QRFP in adipose tissue is reduced in diet-induced obesity, a mouse model in which plasma concentrations of endotoxins are slightly elevated. The present study investigated the role of metabolic endotoxemia (ME) on QRFP gene regulation. Our results uncovered the expression of QRFP in murine macrophages and cell lines. This expression has been found to be decreased in mice with ME. Low doses of lipopolysaccharide (LPS) transiently down-regulated QRFP by 59% in RAW264.7 macrophages but not in 3T3-L1 adipocytes. The effect of LPS on QRFP expression in macrophages was dependent on the inhibitor of kB kinase and TIR-domain-containing adapter-inducing interferon (IFN)-ß (TRIF) but not myeloid differentiation primary response gene 88. IFN-ß was induced by ME in macrophages. IFN-ß sustainably reduced QRFP expression in macrophages (64%) and adipocytes (49%). IFN-γ down-regulated QRFP (74%) in macrophages only. Both IFNs inhibited QRFP secretion from macrophages. LPS-stimulated macrophage-conditioned medium reduced QRFP expression in adipocytes, an effect blocked by IFN-ß neutralizing antibody. The effect of IFN-ß on QRFP expression was dependent on phosphoinositide 3-kinase, p38 MAPK, and histone deacetylases. The effect of IFN-γ was dependent on MAPK/ERK kinase 1/2 and histone deacetylases. Macrophage-conditioned medium containing increased amounts of QRFP preserved adipogenesis in adipocytes. In conclusion, LPS induces IFN-ß release from macrophages, which reduces QRFP expression in both macrophages and adipocytes in an autocrine/paracrine-dependent manner, suggesting QRFP as a potential biomarker in ME.

Cooperative role of endogenous leucotrienes and platelet-activating factor in ischaemia-reperfusion-mediated tissue injury.

Insufficient oxygen delivery to organs leads to tissue dysfunction and cell death. Reperfusion, although vital to organ survival, initiates an inflammatory response that may both aggravate local tissue injury and elicit remote organ damage. Polymorphonuclear neutrophil (PMN) trafficking to remote organs following ischaemia/reperfusion (I/R) is associated with the release of lipid mediators, including leucotriene (LT) B4 , cysteinyl-LTs (CysLTs) and platelet-activating factor (PAF). Yet, their potentially cooperative role in regulating I/R-mediated inflammation has not been thoroughly assessed. The present study aimed to determine the cooperative role of lipid mediators in regulating PMN migration, tissue oedema and injury using selective receptor antagonists in selected models of I/R and dermal inflammation. Our results show that rabbits, pre-treated orally with BIIL 284 and/or WEB 2086 and MK-0571, were protected from remote tissue injury following I/R or dermal inflammation in an additive or synergistic manner when the animals were pre-treated with two drugs concomitantly. The functional selectivity of the antagonists towards their respective agonists was assessed in vitro, showing that neither BIIL 284 nor WEB 2086 prevented the inflammatory response to IL-8, C5a and zymosan-activated plasma stimulation. However, these agonists elicited LTB4 biosynthesis in isolated rabbit PMNs. Similarly, a cardioprotective effect of PAF and LTB4 receptor antagonists was shown following myocardial I/R in mice. Taken together, these results underscore the intricate involvement of LTB4 and PAF in each other's responses and provide further evidence that targeting both LTs and PAF receptors provides a much stronger anti-inflammatory effect, regulating PMN migration and oedema formation.