Chemoattractant Mediators Research Articles

Modulation of Beta-Amyloid-Activated Primary Human Neutrophils by Dietary Phenols from Virgin Olive Oil.

The defense mechanism against harmful stimuli is inflammation. Indeed, neurodegenerative disorders can arise as a result of a persistent neuroinflammation. Beta-amyloid (Aβ1-42) is an early trigger in the origination of Alzheimer's disease, leading to synaptic and cognitive impairments. Virgin olive oil (VOO) is correlated with a decreased risk of developing immune-inflammatory disorders, but the potential effects of the phenolic fraction (PF) from VOO in the modulation of neuroinflammatory processes in neutrophils remain unknown. In this study, we investigated the ability of the PF to modulate the activation of Aβ1-42-stimulated primary human neutrophils, focusing on the expression of gene and surface markers and the release of pro-inflammatory and chemoattractant mediators. Down-regulation of pro-inflammatory cytokine gene expression in Aβ1-42-treated neutrophils, among other changes, was reported. Furthermore, pretreatment with PF prevented neutrophil activation. The beneficial effects in the modulation of inflammatory responses show the relevance of VOO to achieve a healthier diet that can help prevent inflammatory diseases.

Nutrition, Healthcare Benefits and Phytochemical Properties of Cassava (Manihot esculenta) Leaves Sourced from Three Countries (Reunion, Guinea, and Costa Rica)

(1) Background: Manihot esculenta, cassava, is an essential food crop for human consumption in many parts of the world. Besides the wide use of its roots, cassava leaves have been used locally as green vegetables and for medicinal purposes. However, nutritional health data regarding cassava leaves is limited, therefore we investigated its composition and associated potential bioactivity interest for human health. (2) Methods: Cassava leaf bioactivity investigations focused on antioxidant properties (free radical scavenging) in association with immunomodulatory activities on inflammatory murine macrophages to measure the impact of cassava extract on the production of pro-inflammatory cytokines such as Interleukin-6, Tumor Necrosis Factor alpha, Monocyte Chemoattractant Protein-1, Prostaglandin-E2 and mediators such as nitric oxide. (3) Results: Antioxidant and immunomodulatory bioactivities were significant, with a concentration-dependent inhibition of cytokines production by inflammatory macrophages; (4) Conclusions: Taken together, our results tend to suggest that Manihot esculenta leaves might be underrated regarding the potential nutrition-health interest of this vegetal matrix for both human nutrition and prophylaxis of metabolic disease with underlying low grade inflammation status.

Features of the Composition of Cytokines of Various Biological Effects in Patients with Uveal Melanoma: Analysis of Blood Serum. Part 2

Purpose. Conduct extended analysis of cytokine status and its role in inflammatory processes in uveal melanoma based on multiplex analysis of blood serum.Patients and methods. Immunological studies of blood serum and lacrimal fluid were performed in 80 patients with uveal melanoma and 38 healthy donors (control group). The average age of the surveyed was 53.7 ± 12.2 years. Group 1 included 32 patients with small-sized choroidal melanoma (T1NoMo), group 2 consisted of 26 patients with medium-sized tumors (T2NoMo), group 3 — 22 patients with large tumor size (T3NoMo). Cytokine content was determined in blood serum by the method of multiplex analysis on the xMAP platform in the Luminex xPONENT 3.1 program using 47 plex kits (ProcartaPlex, eBioscience, Austria).Results. In blood serum — increase of pro-inflammatory (LIF, RANTES, IP-10), anti-inflammatory (TGF-1β), proliferative (IL-15), pro-tumor (EGF), angiogenic (PIGF-1 and SDF-1α) cytokines compared with control group, p < 0.05.Conclusion. In response to the manifestation and growth of uveal melanoma, many chemoattractant mediators of proinflammatory, angiogenic, proliferative action are produced that promote metastasis. The study of cytokines at the systemic level in serum leads to a deeper understanding of the pathophysiology of carcinogenesis and to facilitate the development of targeted therapies for inhibiting tumor growth.

Features of the Composition of Cytokines of Various Biological Effects in Patients with Uveal Melanoma: Local Changes in the Lacrimal Fluid. Part 1

Purpose. Conduct an extended analysis of the cytokine status and its role in inflammatory processes in uveal melanoma based on multiplex analysis of the tear fluid.Patients and methods. Immunological studies of blood serum and lacrimal fluid were performed in 80 patients with uveal melanoma and 38 healthy donors (control group). The average age of the surveyed was 53.7 ± 12.2 years. Group 1 included 32 patients with small-sized choroidal melanoma (T1NoMo), group 2 consisted of 26 patients with medium-sized lesions (T2NoMo), group 3 — 22 patients with large tumor sizes (T3NoMo). The cytokine content in the tear fluid was determined by the method of multiplex analysis on the xMAP platform in the Luminex xPONENT 3.1 software using 47 plex kits (ProcartaPlex, eBioscience, Austria).Results. In the lacrimal fluid of the patient and the paired eye — an increase in pro-inflammatory (IL-1α, IL-2, IL-6, IL-17A, IL-18, TNF-α, MCP-1, MIP-1α, RANTES, GRO-α, IL-8, IP-10), anti-inflammatory (IL-1RA, IL-4, IL-10, IL-5, TGF-1β), proliferative (FGF-2, HGF, IL-15, PDGF-BB, Eotaxin), pro-tumor (NGF-β, IL-7), antitumor (IL-21), angiogenic (VEGF-A, SDF-1α) cytokines in the initial stage of uveal melanoma compared with the control group, p < 0.05.Conclusion. In response to the manifestation and growth of uveal melanoma, many chemoattractant mediators are produced, including pro-inflammatory and angiogenic effects, which promote tumor progression and affect the body’s immune response. The study of the lacrimal fluid proved the imbalance of the local immunity not only of the patient, but also of the paired «healthy eye». Research into cytokines leads to a deeper understanding of the pathophysiology of carcinogenesis and may contribute to the development of targeted therapies for inhibiting tumor growth.

Periostin: A Potential Biomarker and Therapeutic Target in Pulmonary Diseases.

Periostin is a matricellular, nonstructural protein belonging to the fasciclin family and is encoded by the POSTN gene in humans. Periostin plays an important role in maintaining a normal tissue matrix in the lungs. Despite the vital role as a structural mediator in tissue growth and repair, periostin is involved in the pathogenic mechanism during tissue remodeling and fibrosis. Periostin is a chemoattractant mediator, promotes eosinophil recruitment and adhesion on the airways sub-epithelial membrane of asthmatic patients. POSTN gene was identified as one of the highly expressed genes induced by interleukins IL-13, IL-5 and IL-4 - the key cytokines of Th2 immune responses in the bronchial tissues of asthmatic patients. This review highlights the potential role of periostin as a validated biomarker in respiratory disease progression and its candidacy to predict the response to treatments targeting Th-2 cytokines in bronchial asthma. In addition, its potential role in COPD, IPF, lung cancer and lung infection, is also speculated. Keywords Periostin, Asthma, Pneumonia, COPD, Idiopathic pulmonary fibrosis, Biomarker.

Nox2 underpins microvascular inflammation and vascular contributions to cognitive decline

Chronic microvascular inflammation and oxidative stress are inter-related mechanisms underpinning white matter disease and vascular cognitive impairment (VCI). A proposed mediator is nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (Nox2), a major source of reactive oxygen species (ROS) in the brain. To assess the role of Nox2 in VCI, we studied a tractable model with white matter pathology and cognitive impairment induced by bilateral carotid artery stenosis (BCAS). Mice with genetic deletion of Nox2 (Nox2 KO) were compared to wild-type (WT) following BCAS. Sustained BCAS over 12 weeks in WT mice induced Nox2 expression, indices of microvascular inflammation and oxidative damage, along with white matter pathology culminating in a marked cognitive impairment, which were all protected by Nox2 genetic deletion. Neurovascular coupling was impaired in WT mice post-BCAS and restored in Nox2 KO mice. Increased vascular expression of chemoattractant mediators, cell-adhesion molecules and endothelial activation factors in WT mice post-BCAS were ameliorated by Nox2 deficiency. The clinical relevance was confirmed by increased vascular Nox2 and indices of microvascular inflammation in human post-mortem subjects with cerebral vascular disease. Our results support Nox2 activity as a critical determinant of VCI, whose targeting may be of therapeutic benefit in cerebral vascular disease.

Prolactin modifies the in vitro LPS-induced chemotactic capabilities in human fetal membranes at the term of gestation.

ProblemImmune responses of fetal membranes involve the production of chemoattractant mediators causing infiltration of maternal and fetal leukocytes, intrauterine inflammation and potentially the disruption of maternal‐fetal tolerance. Prolactin (PRL) has deep immunoregulatory effects in the fetal‐maternal interface. We aimed to test the in vitro PRL effect upon chemotactic capacities of human fetal membranes.Method of StudyFetal membranes and umbilical cord blood were collected from healthy non‐laboring caesarean deliveries at term. Fetal membranes were cultured in Transwell® frames to mimic the barrier function between choriodecidual and amniotic sides. Tissues were treated with PRL, Lipopolysaccharide (LPS), or both simultaneously. Then, RANTES, MCP‐1, MIP‐1α, IP‐10, and PECAM‐1 were quantified in a conditioned medium by choriodecidual or amniotic sides. The chemotaxis of subsets of migrating mononuclear cells from umbilical cord blood was evaluated in a Boyden Chamber in response to the conditioned medium by both sides.ResultsLipopolysaccharide stimulates the production of RANTES, MCP‐1, MIP‐1α, and PECAM‐1 in choriodecidua, while MIP‐1α and PECAM‐1 only increase in amnion. PRL decrease RANTES, MCP‐1, and MIP‐1 only in choriodecidua, but PECAM‐1 was decreased mainly in amnion. The leukocyte migration was regulated significantly in response to the conditioned medium by the amnion, increase in the conditioned medium after LPS treatment, contrary with, the leukocyte migration decreased in a significant manner in response to conditioned medium after PRL and LPS‐PRL co‐treatment. Finally, T cells were the most responsive subset of cells.ConclusionsProlactin modified in a tissue‐specific manner the chemotactic factor and the leukocyte migration differentially in fetal membranes.

Features of local and systemic production of pro-inflammatory, chemoattractant mediators and vascular growth factors in high-risk corneal transplants.

Purpose: to study the composition and content of proinflammatory cytokines, chemoattractant mediators, vascular growth factors in blood serum (SB) and lacrimal fluid (LF) in patients with KPHR. Materials and methods. A total of 106 patients with postinflammatory corneal spots and turbid transplant were examined. The control group consisted of 20 practically healthy donors. Cytokines: IL-2, IL-18, MCP-1 / CCL2, MIP-1β / CCL4, RANTES / CCL5, Eotaxin / CCL11, IP-10 / CXCL10, SDF-1α / CXCL12, VEGF-A, VEGF-D, PIGF-1, HGF / SF. Results. The study of the levels of systemic production of immunomodiators in the groups of patients revealed significant changes in the concentrations of MCP-1 / CCL2, RANTES / CCL5, Eotaxin / CCL11, IP-10 / CXCL10, SDF-1α / CXCL12, as well as angiogenic factors VEGF-A and HGF / SF compared to controls. In the group of primary KPHR in the presence of vascularization, an increase in the production of IL-18, RANTES / CCL5, Eotaxin / CCL11 was observed. 1 / CCL2, VEGF-A, PIGF-1 and HGF / SF (p<0.05). Graft vascularization in repeated (2 and higher) corneal transplants (group II) was associated with significant increases in SC IL-2, PIGF-1, and HGF/SF (p<0.05). Analysis of cytokine content in the LF of patients with repeated KPHR and vascularized graft showed a statistically significant increase in IP-10 / CXCL10, MIP-1β / CCL4, SDF-1α / CXCL12, and VEGF-A. A retrospective analysis of the content of cytokines in the SB, depending on the outcomes of keratoplasty, showed a significant increase in the concentration of 7 out of 11 studied cytokines in patients of the KPHR group with various complications in the postoperative period, including those with a developed graft rejection reaction. Conclusions. It has been shown that the formation of vascularized corneal spots is associated with a significant increase in systemic production of IL-18, an increase in the concentration of chemokines with angiogenic activity RANTES / CCL5 and Eotaxin / CCL11 in the blood of patients with KPHR. During vascularization of the graft with repeated KPHR in the SB and LF, a unidirectional increase in the levels of IL-2, MCP-1 / CCL2, growth of VEGF-A and HGF / SF is observed. A factor in the development of graft rejection is the initially high concentrations in the SB of patients with KPHR IL-2, IL-18, chemokines RANTES / CCL5, MIP1β / CCL4, VEGF-A, PLGF, HGF / SF (p<0.05), indicating about the activation of pathological angiogenesis against the background of inflammation and an activated adaptive immune response.

Nutraceutical Extract from Dulse (Palmaria palmata L.) Inhibits Primary Human Neutrophil Activation.

Palmaria palmata L. (Palmariaceae), commonly known as “dulse”, is a red alga that grows on the northern coasts of the Atlantic and Pacific oceans, and is widely used as source of fiber and protein. Dulse is reported to contain anti-inflammatory and antioxidant compounds, albeit no study has investigated these effects in primary human neutrophils. Implication strategies to diminish neutrophil activation have the potential to prevent pathological states. We evaluated the ability of a phenolic dulse extract (DULEXT) to modulate the lipopolysaccharide (LPS)-mediated activation of primary human neutrophils. Intracellular reactive oxygen species (ROS) were measured by fluorescence analysis and nitric oxide (NO) production using the Griess reaction. Inflammatory enzymes and cytokines were detected by ELISA and RT-qPCR. The results show that DULEXT diminished the neutrophil activation related to the down-regulation of TLR4 mRNA expression, deceased gene expression and the LPS-induced release of the chemoattractant mediator IL-8 and the pro-inflammatory cytokines IL-1β, IL-6 and TNF-α. ROS, NO, and myeloperoxidase (MPO) were also depressed. The data indicated that DULEXT has the potential to disrupt the activation of human primary neutrophils and the derived inflammatory and prooxidant conditions, and suggest a new role for Palmaria palmata L. in the regulation of the pathogenesis of health disorders in which neutrophils play a key role, including atherosclerosis.

Substance P-regulated leukotriene B4 production promotes acute pancreatitis-associated lung injury through neutrophil reverse migration

Leukotriene B4 (LTB4) is a potent chemoattractant and inflammatory mediator involved in multiple inflammatory diseases. Substance P (SP) has been reported to promote production of LTB4 in itch-associated response in vivo and in some immune cells in vitro. Here, we investigated the role of LTB4 in acute pancreatitis (AP), AP-associated acute lung injury (ALI) and the related mechanisms of LTB4 production in AP. In vivo, murine AP model was induced by caerulein and lipopolysaccharide or L-arginine. The levels of LTB4 and its specific receptor BLT1 were markedly upregulated in both AP models. Blockade of BLT1 by LY293111 attenuated the severity of AP, decreased neutrophil reverse transendothelial cell migration (rTEM) into the circulation and alleviated the severity of ALI. In vitro, treatment of pancreatic acinar cells with SP increased LTB4 production. Furthermore, SP treatment increased phosphorylation of protein kinase C (PKC) α and mitogen activated protein kinases (MAPKs), including extracellular signal-regulated kinase (ERK), p-38 MAPK and c-Jun NH2-terminal kinase (JNK). Finally, blockade of neurokinin-1 receptor by CP96345 significantly attenuated the severity of AP and decreased the level of LTB4 when compared to AP group. In summary, these results show that SP regulates the production of LTB4 via PKCα/MAPK pathway, which further promotes AP-associated ALI through neutrophil rTEM.

High-Density Lipoprotein (HDL) Counter-Regulates Serum Amyloid A (SAA)-Induced sPLA2-IIE and sPLA2-V Expression in Macrophages.

Human serum amyloid A (SAA) has been demonstrated as a chemoattractant and proinflammatory mediator of lethal systemic inflammatory diseases. In the circulation, it can be sequestered by a high-density lipoprotein, HDL, which carries cholesterol, triglycerides, phospholipids and apolipoproteins (Apo-AI). The capture of SAA by HDL results in the displacement of Apo-AI, and the consequent inhibition of SAA’s chemoattractant activities. It was previously unknown whether HDL similarly inhibits SAA-induced sPLA2 expression, as well as the resultant HMGB1 release, nitric oxide (NO) production and autophagy activation. Here we provided compelling evidence that human SAA effectively upregulated the expression and secretion of both sPLA2-IIE and sPLA2-V in murine macrophages, which were attenuated by HDL in a dose-dependent fashion. Similarly, HDL dose-dependently suppressed SAA-induced HMGB1 release, NO production, and autophagy activation. In both RAW 264.7 cells and primary macrophages, HDL inhibited SAA-induced secretion of several cytokines (e.g., IL-6) and chemokines (e.g., MCP-1 and RANTES) that were likely dependent on functional TLR4 signaling. Collectively, these findings suggest that HDL counter-regulates SAA-induced upregulation and secretion of sPLA2-IIE/V in addition to other TLR4-dependent cytokines and chemokines in macrophage cultures.

Elevated chemokine levels during adult but not pediatric Crimean–Congo hemorrhagic fever

BackgroundCrimean–Congo hemorrhagic fever (CCHF) is a tick-borne viral zoonosis. Clinical reports indicate the severity of CCHF is milder in children than adults. The chemokines are important chemo-attractant mediators of the host immune system. ObjectivesThe main aim of the study was to identify whether or not there were any differences in chemokine levels between the pediatric and adult patients and control groups, and whether there was any correlation with disease severity. Study designThe serum levels of select chemokines including chemokine (C-C) ligand 2 (CCL2), CCL3, CCL4, chemokine (C-X-C) ligand 8 (CXCL8), CXCL9, and granulocyte-colony stimulating factor (G-CSF) in 29 adult and 32 pediatric CCHF patients and in 35 healthy children and 40 healthy adult control groups were studied by flow cytometric bead immunoassay method. ResultsGreat variability was detected in the serum levels of the chemokines for both the adult and pediatric patients and controls. With the exception of G-CSF, the median serum levels of CCL2, CCL3, CCL4, CXCL8, and CXCL9 were found to be significantly higher in the adult patients compared to adult controls (2364.7 vs. 761pg/ml; 714.1 vs. 75.2pg/ml; 88.6 vs. 25.5pg/ml; 217.9 vs. 18.3pg/ml; 875 vs. 352.2pg/ml, respectively, p<0.0001 for all comparisons). Among the chemokines the median CCL4 and G-CSF levels were significantly higher in the pediatric patients compared to pediatric controls (40.3 vs. 7.1pg/ml, p<0.0001; 0.1 vs. 0.1pg/ml, p=0.049, respectively). ConclusionThe results of this study showed prominent chemokine raising in adult CCHF patients compared to children CCHF patients.

The CXCR3-CXCL11 signaling axis mediates macrophage recruitment and dissemination of mycobacterial infection.

The recruitment of leukocytes to infectious foci depends strongly on the local release of chemoattractant mediators. The human CXC chemokine receptor 3 (CXCR3) is an important node in the chemokine signaling network and is expressed by multiple leukocyte lineages, including T cells and macrophages. The ligands of this receptor originate from an ancestral CXCL11 gene in early vertebrates. Here, we used the optically accessible zebrafish embryo model to explore the function of the CXCR3-CXCL11 axis in macrophage recruitment and show that disruption of this axis increases the resistance to mycobacterial infection. In a mutant of the zebrafish ortholog of CXCR3 (cxcr3.2), macrophage chemotaxis to bacterial infections was attenuated, although migration to infection-independent stimuli was unaffected. Additionally, attenuation of macrophage recruitment to infection could be mimicked by treatment with NBI74330, a high-affinity antagonist of CXCR3. We identified two infection-inducible CXCL11-like chemokines as the functional ligands of Cxcr3.2, showing that the recombinant proteins exerted a Cxcr3.2-dependent chemoattraction when locally administrated in vivo. During infection of zebrafish embryos with Mycobacterium marinum, a well-established model for tuberculosis, we found that Cxcr3.2 deficiency limited the macrophage-mediated dissemination of mycobacteria. Furthermore, the loss of Cxcr3.2 function attenuated the formation of granulomatous lesions, the typical histopathological features of tuberculosis, and led to a reduction in the total bacterial burden. Prevention of mycobacterial dissemination by targeting the CXCR3 pathway, therefore, might represent a host-directed therapeutic strategy for treatment of tuberculosis. The demonstration of a conserved CXCR3-CXCL11 signaling axis in zebrafish extends the translational applicability of this model for studying diseases involving the innate immune system.

Differential requirement of C3a receptor in APC-driven emphysema in response to cigarette smoke (P6225)

Abstract Pathogenic lung antigen presenting cells (APCs) are abundant in the lungs of smokers with emphysema and are capable of inducing T helper type 1 (Th1) and Th17 cell differentiation. Mice exposed to chronic cigarette smoke develop emphysema and harbor CD11b+CD11c+ APCs that can transfer the disease to naïve mice. Proteolytic products from activated innate immune cells cleave complement proteins but the contribution of their downstream signaling in APC-driven lung parenchyma destruction is less clear. We show here that relative to control smokers, complement 3 (C3) is increased in the plasma and its cleaved products are deposited on the lung tissue of smokers with advanced lung disease. Matrix metalloproteinase 12 and neutrophils elastase directly cleave human C3, and generate multiple activated signaling products. Compared to wild type, C3 deficient mice exposed to chronic smoke showed reduced CD11b+CD11c+ cells in the lungs and were protected against emphysema development. C3a and C5a, two of the major anaphylatoxin and chemoattractant mediators downstream of C3 activation, are present in the lungs of mice exposed to smoke, but only C3a signaling was critical in emphysema development because deficiency in C3a receptor (C3aR) but not C5aR phenocopied C3-/- mice in this model. These findings suggest a critical role for C3aR in the pathogenesis of smoke induced lung disease, and could be explored to develop specific new therapeutic targets for emphysema treatment.

Phosphoinositide 3-Kinases and Leukocyte Migration

Phosphoinositide 3-kinase (PI3K) has been positioned at the heart of an evolutionarily conserved cellular compass and/or the biochemical mechanisms that facilitate cell migration. PI3K has therefore, become a popular drug target for inhibition of leukocyte migration in response to inflammatory chemoattractant mediators including members of the chemokine family. PI3K has also been implicated as a key regulator in novel mechanisms mediated by the T cell antigen receptor and the costimulatory molecule CD28 that guide the access and retention of specific T cells into antigenrich non-lymphoid tissue. The precise role of PI3K in the regulation of cell migration remains open to refinement, as numerous examples of PI3K-independent leukocyte migration (particularly with respect to T lymphocytes), have been described. The best studied leukocytes in terms of their migratory response and the role of PI3K are neutrophils and macrophages (that constitute the innate immune response), T lymphocytes (key elements of the adaptive immune response) and eosinophils (typical infiltrating cells at the sites of allergen-IgE reactions that constitute a link between innate and adaptive systems). Genetic and pharmacological approaches have been employed to assess the contribution of individual class 1 PI3K isoforms to migratory response of these leukocytes and will be considered in this article. Keywords: Chemokine, inflammation, leukocyte, migration, PI3K, TCR

Hepoxilins in cancer and inflammation—use of hepoxilin antagonists

Cancer is often accompanied with inflammatory, thrombotic, and diabetic complications. Alternatively, chronic inflammation is believed to be a causative factor in several cancers. This review article brings together reported biological actions in these areas of the unstable naturally derived hepoxilins (HX), metabolites of arachidonic acid formed through the 12-LO pathway, and those of their synthetically derived stable HX antagonists (PBT; proprietary bioactive therapeutics). Although the HX pathway has been known for some three decades since its discovery by the author with much data originating from the author's laboratory, studies by others over the past few years have confirmed early findings of the actions of HX as potent pro-inflammatory chemoattractant mediators and further showed HX to be involved in bacterial infection (Salmonella-induced intestinal inflammation and in bone inflammation caused by infection with the Lyme bacterium). The HX pathway appears to be an important early signal leading to inflammation. This provides important therapeutic potential for the PBTs as the only available selective antagonists of this pathway. The PBTs have shown benefit and efficacy in animal models of cancer and inflammation, which together with their known actions as anti-thrombotic (thromboxane (TPα) receptor antagonists) and hypoglycemic agents in vivo appears to make the PBTs suitable as therapeutics to control these disorders. The PBT structure is both stable in vivo and is essentially devoid of side effects in the animal models tested. The PBT structure serves as an important platform for selective HX and TX antagonists.

Chemokines: Sirens of Neutrophil Recruitment—but Is It Just One Song?

Neutrophil trafficking to inflamed tissues requires the integration of multiple chemoattractant guidance signals. In this issue of Immunity, Chou et al. (2010) demonstrate that collaborative "cascades" of chemoattractant mediators control neutrophil recruitment to arthritic joints in mice.

Anti-inflammatory potential of 2-styrylchromones regarding their interference with arachidonic acid metabolic pathways

Cyclooxygenases (COXs) are the key enzymes in the biosynthesis of prostanoids. COX-1 is a constitutive enzyme while the expression of COX-2 is highly stimulated in the event of inflammatory processes, leading to the production of large amounts of prostaglandins (PGs), in particular PGE 2 and PGI 2, which are pro-inflammatory mediators. Lipoxygenases (LOXs) are enzymes that produce hydroxy acids and leukotrienes (LTs). 5-LOX metabolizes arachidonic acid to yield, among other products, LTB 4, a potent chemoattractant mediator of inflammation. The aim of the present work was to evaluate the anti-inflammatory potential of 2-styrylchromones (2-SC), a chemical family of oxygen heterocyclic compounds, vinylogues of flavones (2-phenylchromones), by studying their COX-1 and COX-2 inhibitory capacity as well as their effects on the LTB 4 production by stimulated human polymorphonuclear leukocytes (PMNL). Some of the tested 2-SC were able to inhibit both COX-1 activity and LTB 4 production which makes them dual inhibitors of the COX and 5-LOX pathways. The most effective compounds in this study were those having structural moieties with proved antioxidant activity (3′,4′-catechol and 4′-phenol substituted B-rings). This type of compounds may exhibit anti-inflammatory activity with a wider spectrum than that of classical non-steroidal anti-inflammatory drugs (NSAIDs) by inhibiting 5-LOX product-mediated inflammatory reactions, towards which NSAIDs are ineffective.

Leukotriene B4 enhances the activity of nuclear factor- B pathway through BLT1 and BLT2 receptors in atherosclerosis

Leukotriene B4 (LTB4) is a powerful chemoattractant and pro-inflammatory mediator in several inflammatory diseases, including atherosclerosis. It acts through its two membrane receptors, BLT1 and BLT2. The aim of this study was to determine the molecular mechanism involved in the proatherogenic effect of LTB4, BLT1 and BLT2 in atherosclerosis. Moreover, we characterized the expression of 5-lipoxygenase (5-LO) pathway and LTB4 receptors in blood and plaques from patients with carotid atherosclerosis. In cultured monocytic cells, LTB4 induced a rapid phosphorylation of mitogen-activated protein kinases (MAPKs ERK1/2 and JNK1/2) and PI3K/Akt via BLT1 and BLT2 in a pertussis toxin (PTX)-dependent mechanism (assessed via western blotting) and also increased nuclear factor-kappaB (NF-kappaB) DNA binding activity (assessed via EMSA) in a MAPK- and reactive oxygen species-dependent mechanism. Furthermore, LTB4 elicited interleukin-6, monocyte chemoattractant protein-1 and tumour necrosis factor-alpha mRNA overexpression also via BLT1 and BLT2 by a PTX- and NF-kB-dependent mechanism (assessed by real-time PCR), promoting an inflammatory environment. When compared with healthy subjects, patients with carotid atherosclerosis showed a significant increase in the expression of all the components of the 5-LO pathway and BLT1 and BLT2 mRNA (real-time PCR) in peripheral blood mononuclear cells and LTB4 plasma levels (ELISA). In these patients, an overexpression of 5-LO, leukotriene A-4 hydroxylase (LTA4-H) and BLT1 was noted in the inflammatory region of carotid plaques when compared with the fibrous cap (assessed by immunohistochemistry). The 5-LO pathway is enhanced in patients with carotid atherosclerosis. Furthermore, its product LTB4 phosphorylates MAPKs and stimulates NF-kappaB-dependent inflammation via BLT1 and BLT2 receptors in cultured monocytic cells. The blockade of this pathway could be a novel and potential therapeutic target in atherothrombosis.

Hydrogen Sulfide Augments Neutrophil Migration through Enhancement of Adhesion Molecule Expression and Prevention of CXCR2 Internalization: Role of ATP-Sensitive Potassium Channels

In this study, we have addressed the role of H(2)S in modulating neutrophil migration in either innate (LPS-challenged naive mice) or adaptive (methylated BSA (mBSA)-challenged immunized mice) immune responses. Treatment of mice with H(2)S synthesis inhibitors, dl-propargylglycine (PAG) or beta-cyanoalanine, reduced neutrophil migration induced by LPS or methylated BSA (mBSA) into the peritoneal cavity and by mBSA into the femur/tibial joint of immunized mice. This effect was associated with decreased leukocyte rolling, adhesion, and P-selectin and ICAM-1 expression on endothelium. Predictably, treatment of animals with the H(2)S donors, NaHS or Lawesson's reagent, enhanced these parameters. Moreover, the NaHS enhancement of neutrophil migration was not observed in ICAM-1-deficient mice. Neither PAG nor NaHS treatment changed LPS-induced CD18 expression on neutrophils, nor did the LPS- and mBSA-induced release of neutrophil chemoattractant mediators TNF-alpha, keratinocyte-derived chemokine, and LTB(4). Furthermore, in vitro MIP-2-induced neutrophil chemotaxis was inhibited by PAG and enhanced by NaHS treatments. Accordingly, MIP-2-induced CXCR2 internalization was enhanced by PAG and inhibited by NaHS treatments. Moreover, NaHS prevented MIP-2-induced CXCR2 desensitization. The PAG and NaHS effects correlated, respectively, with the enhancement and inhibition of MIP-2-induced G protein-coupled receptor kinase 2 expression. The effects of NaHS on neutrophil migration both in vivo and in vitro, together with CXCR2 internalization and G protein-coupled receptor kinase 2 expression were prevented by the ATP-sensitive potassium (K(ATP)(+)) channel blocker, glybenclamide. Conversely, diazoxide, a K(ATP)(+) channel opener, increased neutrophil migration in vivo. Together, our data suggest that during the inflammatory response, H(2)S augments neutrophil adhesion and locomotion, by a mechanism dependent on K(ATP)(+) channels.