Platelet-activating Factor Receptor Antagonist Research Articles

Does Yogurt Enriched with Platelet-Activating Factor Inhibitors from Olive Oil By-Products Affect Gut Microbiota and Faecal Metabolites in Healthy Overweight Subjects? (A randomized, parallel, three arm trial.).

The effect of the daily consumption of a low-fat yogurt (150 g) enriched with Platelet-Activating Factor receptor (PAF-R) antagonists, or the plain one, on gut microbiota and faecal metabolites was investigated in healthy overweight subjects. A randomized, three-arm, double-blind, placebo-controlled, parallel-group study was performed that lasted 8 weeks. Blood and stools were collected and analyzed before and after the intervention. Our findings revealed that the intake of the enriched yogurt resulted in a significant increase in the levels of Bifidobacterium spp., Clostridium perfringens group and Firmicutes-to-Bacteroidetes (F/B) ratio. On the other hand, a significant increase in the levels of Lactobacillus and C. perfringens group was detected after the intake of the plain yogurt. The increase in the levels of C. perfringens group was inversely associated with the plasma catabolic enzyme of PAF, namely LpPLA2 (lipoprotein-associated phospholipase A2), a cardiovascular risk marker that has been linked with inflammation and atherosclerosis. Moreover, in the enriched with PAF-R antagonists yogurt group, the increased levels of C. perfringens group were also associated with lower PAF action assessed as ex vivo human platelet-rich plasma (PRP) aggregation. Additionally, a higher % increase in molar ratio of Branched Short Chain Fatty Acids (BSCFAs) was detected for both yogurt groups after the 8 week-intervention compared to control. The consumption of the enriched yogurt also resulted in a significant drop in faecal caproic levels and a trend for lower ratio of butyrate to total volatile fatty acids (VFAs) compared to baseline levels. Yogurt consumption seems to favorably affect gut microbiota while its enrichment with PAF-R antagonists from olive oil by-products, may provide further benefits in healthy overweight subjects. ClinicalTrials.gov (NCT02259205).

Role of Platelet Activation Factor in Patients with Hypersensitive Vasculitis, Autoimmune and Allergic Urticaria

Cutaneous syndrome is a relevant issue not only among allergic diseases but also among autoimmune disorders. Urticaria is a widespread problem, as its prevalence among the population can reach up to 9%. The main goal of the article is to analyze the role of platelet-activating factor in patients with hypersensitive vasculitis, autoimmune, and allergic urticaria. Urticarial rash is at the intersection of allergic and autoimmune diseases, where is observed active immunopathogenetic influence of platelet-activating factor in the initiation and maintenance of systemic vasculitis, including hypersensitive/urticarial and cryoglobulinemic vasculitis Considering the significant role of this factor in the pathogenesis of hypersensitive vasculitis and allergic reactions, selective targeting of platelet-activating factor represents a promising therapeutic approach. These include platelet-activating factor receptor antagonists such as rupatadine and apafant, as well as platelet-activating factor acetylhydrolase inhibitors, enzymes responsible for platelet-activating factor degradation. Targeted intervention on platelet-activating factor holds promise for the improving the quality of life of patients with hypersensitive vasculitis, autoimmune disorders, and allergic urticaria.

Antagonism of the Platelet-Activating Factor Pathway Mitigates Inflammatory Adverse Events Driven by Anti-erythrocyte Antibody Therapy in Mice.

Immune thrombocytopenia (ITP) is an autoimmune disease characterized by low platelet counts primarily due to antiplatelet autoantibodies. Anti-D is a donor-derived polyclonal Ab against the rhesus D Ag on erythrocytes used to treat ITP. Unfortunately, adverse inflammatory/hypersensitivity reactions and a Food and Drug Administration-issued black box warning have limited its clinical use. This underscores the imperative to understand the inflammatory pathway associated with anti-erythrocyte Ab-based therapies. TER119 is an erythrocyte-specific Ab with anti-D-like therapeutic activity in murine ITP, while also exhibiting a distinct inflammatory signature involving production of CCL2, CCL5, and CXCL9 but not IFN-γ. Therefore, TER119 has been used to elucidate the potential mechanism underlying the adverse inflammatory activity associated with anti-erythrocyte Ab therapy in murine ITP. Prior work has demonstrated that TER119 administration is associated with a dramatic decrease in body temperature and inflammatory cytokine/chemokine production. The work presented in the current study demonstrates that inhibiting the highly inflammatory platelet-activating factor (PAF) pathway with PAF receptor antagonists prevents TER119-driven changes in body temperature and inhibits the production of the CCL2, CCL5, and CXCL9 inflammatory cytokines in CD-1 mice. Phagocytic cells and a functional TER119 Fc region were found to be necessary for TER119-induced body temperature changes and increases in CXCL9 and CCL2. Taken together, this work reveals the novel requirement of the PAF pathway in causing adverse inflammatory activity associated with anti-erythrocyte Ab therapy in a murine model and provides a strategy of mitigating these potential reactions without altering therapeutic activity.

Platelet-activating factor and protease-activated receptor 2 cooperate to promote neutrophil recruitment and lung inflammation through nuclear factor-kappa B transactivation

Although it is well established that platelet-activated receptor (PAF) and protease-activated receptor 2 (PAR2) play a pivotal role in the pathophysiology of lung and airway inflammatory diseases, a role for a PAR2-PAFR cooperation in lung inflammation has not been investigated. Here, we investigated the role of PAR2 in PAF-induced lung inflammation and neutrophil recruitment in lungs of BALB/c mice. Mice were pretreated with the PAR2 antagonist ENMD1068, PAF receptor (PAFR) antagonist WEB2086, or aprotinin prior to intranasal instillation of carbamyl-PAF (C-PAF) or the PAR2 agonist peptide SLIGRL-NH2 (PAR2-AP). Leukocyte infiltration in bronchoalveolar lavage fluid (BALF), C-X-C motif ligand 1 (CXCL)1 and CXCL2 chemokines, myeloperoxidase (MPO), and N-acetyl-glycosaminidase (NAG) levels in BALF, or lung inflammation were evaluated. Intracellular calcium signaling, PAFR/PAR2 physical interaction, and the expression of PAR2 and nuclear factor-kappa B (NF-КB, p65) transcription factor were investigated in RAW 264.7 cells stimulated with C-PAF in the presence or absence of ENMD1068. C-PAF- or PAR2-AP-induced neutrophil recruitment into lungs was inhibited in mice pretreated with ENMD1068 and aprotinin or WEB2086, respectively. PAR2 blockade impaired C-PAF-induced neutrophil rolling and adhesion, lung inflammation, and production of MPO, NAG, CXCL1, and CXCL2 production in lungs of mice. PAFR activation reduced PAR2 expression and physical interaction of PAR2 and PAFR; co-activation is required for PAFR/PAR2 physical interaction. PAR2 blockade impaired C-PAF-induced calcium signal and NF-κB p65 translocation in RAW 264.7 murine macrophages. This study provides the first evidence for a cooperation between PAFR and PAR2 mediating neutrophil recruitment, lung inflammation, and macrophage activation.

Platelet-activating factor antagonist-based intensive antiplatelet strategy in acute ischemic stroke: A propensity score matched with network pharmacology analysis.

Diterpene ginkgolides meglumine injection (DGMI) is a platelet-activating factor receptor (PAFR) antagonist that can be used to treat acute ischemic stroke (AIS). This study evaluated the efficacy and safety of an intensive antiplatelet strategy based on PAFR antagonists and explored the underlying mechanisms of PAFR antagonists in AIS treatment. This is a retrospective study applying propensity score methods to match AIS patients treated with DGMI to nontreated patients. The primary outcome was functional independence (modified Rankin Scale [mRS] 0-2) at 90 days. The safety outcome was bleeding risk. We used McNemar test to compare the efficacy outcome. Subsequently, the network pharmacology analysis was performed. 161 AIS patients treated with DGMI in the study were matched with 161 untreated patients. Compared with untreated patients, DGMI-treated patients had a significantly higher rate of mRS ranking 0-2 at 90 days (82.0% vs. 75.8%, p < 0.001), without increased risk of bleeding. The gene enrichment analysis showed that the overlap genes of DGMI targeted and AIS-related enriched in thrombosis and inflammatory-related signaling pathways. An intensive antiplatelet strategy of DGMI plus traditional antiplatelet agents is effective in treating AIS and may work by mediating post-stroke inflammation and thrombosis.

Myocardial ischemia-reperfusion injury is probably due to the excessive production of mitochondrial ROS caused by the activation of 5-HT degradation system mediated by PAF receptor.

Previously, we revealed a crucial role of 5-HT degradation system (5DS), consisting of 5-HT2A receptor (5-HT2AR), 5-HT synthases and monoamine oxidase A (MAO-A), in ischemia-reperfusion (IR)-caused organ injury. Whereas, platelet activating factor receptor (PAFR) also mediates myocardial ischemia-reperfusion injury (MIRI). Here, we try to clarify the relationship between 5DS and PAFR in mediating MIRI. H9c2 cell injury and rat MIRI were caused by hypoxia/reoxygenation (H/R) or PAF, and by ligating the left anterior descending coronary artery then untying, respectively. 5-HT2AR and PAFR antagonists [sarpogrelate hydrochloride (SH) and BN52021], MAO-A, AKT, mTOR and 5-HT synthase inhibitors (clorgyline, perifosine, rapamycin and carbidopa), and gene-silencing PKCε were used in experiments RESULTS: The mitochondrial ROS production, respiratory chain damage, inflammation, apoptosis and myocardial infarction were significantly prevented by BN52021, SH and clorgyline in H/R and PAF-treated cells and in IR myocardium. BN52021 also significantly suppressed the upregulation of PAFR, 5-HT2AR, 5-HT synthases and MAO-A expression (mRNA and protein), and Gαq and PKCε (in plasmalemma) expression induced by H/R, PAF or IR; the effects of SH were similar to that of BN52021 except for no affecting the expression of PAFR and 5-HT2AR. Gene-silencing PKCε suppressed H/R and PAF-induced upregulation of 5-HT synthases and MAO-A expression in cells; perifosine and rapamycin had not such effects; however, clorgyline suppressed H/R and PAF-induced phosphorylation of AKT and mTOR. MIRI is probably due to PAFR-mediated 5-HT2AR activation, which further activates PKCε-mediated 5-HT synthesis and degradation, leading to mitochondrial ROS production.

Abstract TP212: Robust Neuroprotection With PAF-R Antagonist Plus AT-NPD1 In Experimental Ischemic Stroke: Dose-response And Therapeutic Window

Objective: We examined the neuroprotective efficacy, including dose-responses and therapeutic window of 1) LAU-0901, receptor antagonist of the bioactive phospholipid mediator platelet-activating factor (PAF-R) that downregulates pro-inflammatory signaling and has been shown efficacy in a stroke model and, 2) AT-NPD1 (Aspirin- triggered NPD1), its synthesis in the brain was discovered upon aspirin + DHA administration (Bazan et al. Exp Neurol., 2012) and induced cell-survival pathways, anti-inflammatory and neuroprotective activity in focal cerebral ischemia. Methods: Male SD rats underwent 2 hours of MCAo. Behavior testing (days 1-7) and ex vivo MRI on day 7 were conducted. In dose-response, rats were treated with LAU-0901 (45 and 60 mg/kg; IP), AT-NPD1 (111, 222, 333 μg/kg; IV), LAU-0901+AT-NPD1 (LAU-0901 at 3h and AT-NPD1 at 3.15h) or vehicle. In the therapeutic window, vehicle LAU-0901 (60 mg/kg), AT-NPD1 (222 μg/kg), and LAU-0901+AT-NPD1 were administered at 3, 4, 5, and 6h after onset of MCAo. Rats were perfused on day 7, and an ex vivo brain MRI was conducted using 11.7 T MRI. Hierarchal region splitting was used to distinguish the core from the penumbra. Results: LAU-0901 and AT-NPD1 treatments alone improved behavior by 40-42% and 20-30%, respectively, and LAU-0901+AT-NPD1 by 40% compared to the vehicle group. T2-weighted imaging (T2WI) volumes were reduced with all doses of LAU-0901 and AT-NPD1 by 73-90% and 67-83% and LAU-0901+AT-NPD1 by 94% compared to vehicle. In the therapeutic window, treatment with LAU-0901 and AT-NPD1 alone, when administered at 3h, improved behavior on day 7 by 35 and 28%. In contrast, LAU-0901+AT-NPD1, when administered at 3, 4, 5, and 6 hours, improved behavior by 50, 56, 33, and 26%. Ischemic core, penumbra, and total lesion volumes were dramatically reduced with LAU-0901+AT-NPD1 when administered at 3, 4, 5, and 6h by 93, 90, 82, and 84% compared to the vehicle. Conclusion: These data suggest that LAU-0901 and AT-NPD1 alone in low doses provide high-grade neuroprotection in the MCAo model. Combination therapy with LAU-0901 and AT-NPD1 is more effective than the single therapy, affording synergistic neuroprotection with improved neurological recovery when administered up to 6 h after focal cerebral ischemia in rats.

Tumor-associated neutrophils and macrophages exacerbate antidrug IgG-mediated anaphylactic reaction against an immune checkpoint inhibitor

BackgroundWith the increased use of immune checkpoint inhibitors (ICIs), side effects and toxicity are a great concern. Anaphylaxis has been identified as a potential adverse event induced by ICIs. Anaphylaxis...

SI: PAF: Topical application of gemcitabine generates microvesicle particles in human and murine skin.

Chemotherapy has remained the mainstay for the treatment of multiple types of cancers. In particular, topical use of chemotherapy has been used for skin cancers. Though effective, topical chemotherapy has been limited due to adverse effects such as local and even systemic toxicities. Our recent studies demonstrated that exposure to pro-oxidative stressors, including therapeutic agents induces the generation of extracellular vesicles known as microvesicle particles (MVP) which are dependent on activation of the Platelet-activating factor-receptor (PAFR), a G-protein coupled receptor present on various cell types, and acid sphingomyelinase (aSMase), an enzyme required for MVP biogenesis. Based upon this premise, we tested the hypothesis that topical application of gemcitabine will induce MVP generation in human and murine skin. Our ex vivo studies using human skin explants demonstrate that gemcitabine treatment results in MVP generation in a dose-dependent manner in a process blocked by PAFR antagonist and aSMase inhibitor. Importantly, gemcitabine-induced MVPs carry PAFR agonists. To confirm the mechanisms, we employed PAFR-expressing and deficient (Ptafr-/- ) mouse models as well as mice deficient in aSMase enzyme (Spmd1-/- ). Similar to the findings using pharmacologic tools, genetic-based approaches demonstrate that gemcitabine-induced MVP release in WT mice was blunted in Ptafr-/- and Spmd1-/- mice. These findings demonstrate a novel mechanism by which local chemotherapy can generate bioactive components as a bystander effect in a process that is dependent upon the PAFR-aSMase pathway.

Targeting the Platelet-Activating Factor Receptor (PAF-R): Antithrombotic and Anti-Atherosclerotic Nutrients.

Platelet-activating factor (PAF) is a lipid mediator that interacts with its receptor (PAF-R) to carry out cell signalling. However, under certain conditions the binding of PAF to PAF-R leads to the activation of pro-inflammatory and prothrombotic pathways that have been implicated in the onset and development of atherosclerotic cardiovascular diseases (CVD) and inflammatory diseases. Over the past four decades, research has focused on the identification and development of PAF-R antagonists that target these inflammatory diseases. Research has also shown that dietary factors such as polar lipids, polyphenols, and other nutrient constituents may affect PAF metabolism and PAF-R function through various mechanisms. In this review we focus on the inhibition of PAF-R and how this may contribute to reducing cardiovascular disease risk. We conclude that further development of PAF-R inhibitors and human studies are required to investigate how modulation of the PAF-R may prevent the development of atherosclerotic cardiovascular disease and may lead to the development of novel therapeutics.

Consumption of yogurt enriched with polar lipids from olive oil by-products reduces platelet sensitivity against platelet activating factor and inflammatory indices: A randomized, double-blind clinical trial

Several studies have reported the positive cardio-metabolic effects of yogurt consumption. The addition of olive oil’s bioactive extracts into yogurt can result to a functional food with pleiotropic properties against cardiovascular diseases. A polar lipid extract of olive pomace (OOPLE) that contains platelet activating factor receptor (PAF-R) antagonists, has been stated not only to inhibit the development of atherosclerotic plaques in hypercholesterolemic rabbits but also to regress the already formed plaques. The present study aims to investigate the effect of the daily intake of an OOPLE-enriched low-fat yogurt, on the metabolic profile, ex vivo platelet aggregation and markers of thrombosis and inflammation, in healthy, mainly overweight volunteers. A randomized, three-arm, double-blind, placebo-controlled, parallel-group, 8 weeks duration, clinical trial was performed in apparently healthy adults (35–65 years old). Group A (control group) consumed at most one yogurt every two weeks, Group B (plain yogurt) consumed one serving of plain yogurt every day and Group C (enriched yogurt) consumed one serving of yogurt, enriched with OOPLE, daily. Enriched yogurt intake resulted in lower levels of IL-10 and to lower platelet sensitivity against PAF, compared to the other two groups (p-values<0.05), while no impact on energy intake, body weight, glucose and lipid metabolism was detected. Lower levels of IL-6 were observed only at 4 weeks enriched yogurt intake (p = 0.03) compared to plain yogurt. Intake of the enriched yogurt resulted in reduced PAF-induced platelet aggregation and suppression of IL-10 levels. NCT02259205.

PAF-induced inflammatory and immuno-allergic ophthalmic diseases and their mitigation with PAF receptor antagonists: Cell and nuclear effects.

Ocular allergies are becoming more prevalent as more airborne pollutants, irritants and microbes pervade our environment. Inflammatory and allergic mediators released by dendritic and mast cells within the conjunctiva cause allergic conjunctivitis (AC), a prevalent ocular surface disorder that affects >40% of the world's human population on a seasonal or perennial basis. Even though histamine is a major culprit, platelet-activating factor (PAF) also contributes to AC, acting either directly or synergistically with histamine and other mediators. PAF receptor-meditated inflammatory reactions, via cell-membrane-bound and nuclear-membrane-bound and nuclear PAF receptors, are also implicated in the etiology of other eye diseases such as uveitis, diabetic retinopathy, corneal and choroidal neovascularization, and age-related macular degeneration which cause serious visual impairment and can lead to blindness. This review highlights the various deleterious elements implicated in the pathological aspects of ocular allergic reactions and inflammation and provides concepts and treatment options to mitigate these eye disorders with a special focus on PAF and PAF receptor antagonists.

Impact of Phosphorylcholine Expression on the Adherence and Invasion of Streptococcus pyogenes to Epithelial Cells.

Phosphorylcholine (PC) is a structural component of various pathogens and is involved in bacterial adhesion via the platelet-activating factor receptor (PAF-R). In this study, we investigated how PC expression affects cell adhesion and invasion of Streptococcus pyogenes (S. pyogenes). Eight clinical strains of S. pyogenes were cultured, and PC expression was measured using fluorescence-activated cell sorting. Bacterial adherence and invasion were examined using Detroit 562 cells. An anti-PC-specific monoclonal antibody (TEPC-15) was used to inhibit bacterial PC, and a PAF-R antagonist (ABT-491) was used to inhibit cellular PAF-R. The emm gene was amplified by the polymerase chain reaction with the standard primers. The level of PC expressed on the S. pyogenes surfaces differed in each strain and differed even in the same emm genotype. Adherence assay experiments showed a significant negative correlation between TEPC-15 and ABT-491 inhibitory effects and PC expression in S. pyogenes. Similarly, intracellular invasion assay experiments showed a significant negative correlation between TEPC-15 and ABT-491 inhibitory effects and PC expression in S. pyogenes. This study suggests that S. pyogenes is involved in cell adhesion and invasion by PC.

Platelet-activating factor (PAF) strongly enhances contractile mechanical activities in guinea pig and mouse urinary bladder

In this study, we investigated the effects of platelet-activating factor (PAF) on the basal tone and spontaneous contractile activities of guinea pig (GP) and mouse urinary bladder (UB) smooth muscle (UBSM) tissues to determine whether PAF could induce UBSM tissue contraction. In addition, we examined the mRNA expression of the PAF receptor, PAF-synthesizing enzyme (lysophosphatidylcholine acyltransferase, LPCAT), and PAF-degrading enzyme (PAF acetylhydrolase, PAF-AH) in GP and mouse UB tissues using RT-qPCR. PAF (10−9–10−6 M) strongly enhanced the basal tone and spontaneous contractile activities (amplitude and frequency) of GP and mouse UBSM tissues in a concentration-dependent manner. The enhancing effects of PAF (10−6 M) on both GP and mouse UBSM contractile activities were strongly suppressed by pretreatment with apafant (a PAF receptor antagonist, GP: 10−5 M; mouse: 3 × 10−5 M). The PAF receptor (Ptafr), LPCAT (Lpcat1, Lpcat2), and PAF-AH (Pafah1b3, Pafah2) mRNAs were detected in GP and mouse UB tissues. These findings reveal that PAF strongly enhances the contractile mechanical activities of UBSM tissues through its receptor and suggest that the PAF-synthesizing and -degrading system exists in UBSM tissues. PAF may serve as both an endogenous UBSM constrictor and an endogenous mediator leading to detrusor overactivity.

Singlet oxygen from endoperoxide initiates an intracellular reactive oxygen species release in HaCaT keratinocytes.

Singlet oxygen (‍1O2) is a selective intermediate reactive oxygen species generated naturally in biological systems by light- and non-light mediated processes. Although ‍1O2 plays an important role in cell signaling and in maintaining homeostasis, it can be toxic due to its ability to diffuse across considerable distances. Several in vitro studies have investigated the pathways by which ‍1O2 mediates oxidation of biological molecules and potential pathogenesis. However, understanding how singlet oxygen exerts cell injury through the production of subsequent reactive oxygen species remains unexplored. To study this, we used a hydrophobic endoperoxide as a source of ‍1O2. Endoperoxides are reagents that quantitatively generate singlet oxygen in solution at 35°C by thermal decomposition. Our chemiluminescence and cell viability assay data revealed that ‍1O2 stimulated a secondary intracellular reactive oxygen species production in a very short time. To determine the source of these reactive oxygen species with endo-peroxide exposure, cells were treated with inhibitors targeting NADPH oxidases and platelet activating factor receptors. Our results showed that addition of the platelet activating factor receptor antagonist, Apafant (WEB2086), alleviated cell injury and hydrogen peroxide levels following endoperoxide stimulation. Furthermore, intracellular calcium assay data demonstrated a potential calcium sensitive production of intracellular reactive oxygen species.

Molecular Modelling Simulations and Inhibitory Effects of Naturally Derived Flavonoids Targeting Platelet-Activating Factor Receptor (PAFR)

Background:Platelet-activating factor (PAF) is an agonist mediator in the inflammatory process, which interacts with PAF receptor (PAFR) that eventually causes cancers, respiratory and neurodegenerative diseases. This interaction activates the mitogen-activated protein kinase (MAPK) pathway, leading to a pro-inflammatory cascade. The pathophysiological conditions due to activation of inflammatory cascade could be inhibited by PAF antagonists.Objectives:In this study, selected naturally derived flavonoids (flavone, biochanin A, and myricetin) with different functional groups were subjected to molecular modelling and experimental studies to investigate their potential as PAF antagonists.Method:Interactions of flavonoids and PAF were assessed via Autodock Vina for molecular docking and the AMBER program for molecular dynamic simulations. The experimentally antagonistic effects of the flavonoids were also conducted via PAF inhibitory assay to determine the IC50 values.Results:The findings of docking and dynamic simulations have revealed that all selected flavonoids interact with PAFR in the binding site with considerably good binding affinity up to - 9.8 kcal mol-1 as compared to cedrol (- 8.1 kcal mol-1) as a standard natural PAFR antagonist. The PAFR-flavonoid complexes exhibited four conserved active site residues, which included W73, F97, F174, and L279. The stability of all complexes was attained in a 30 ns simulation. The findings of in silico analyses were then compared to the experimental study on PAF inhibitory assay. Inhibitory effects of flavonoids against PAFR showed moderate activities, ranging from 27.8 – 30.8 μgM-1.Conclusion:All studied flavonoids could act as promising PAF antagonists with some enhancement in their structures to exhibit potent antagonistic activity. However, these naturally derived flavonoids demand further investigation at cellular and animal models to develop new PAF antagonist drug candidates for treating PAF-mediated diseases.

Compound Kushen Injection Induces Immediate Hypersensitivity Reaction Through Promoting the Production of Platelet-Activating Factor via de Novo Pathway.

Compound Kushen Injection (CKI) is a bis-herbal formulation extracted from Kushen (Radix Sophorae Flavescentis) and Baituling (Rhizoma Heterosmilacis Yunnanensis). Clinically, it is used as the adjuvant treatment of cancer. However, with the increased application, the cases of immediate hypersensitivity reactions (IHRs) also gradually rise. In this study, we investigated the underlying mechanism(s) and active constituent(s) for CKI-induced IHRs in experimental models. The obtained results showed that CKI did not elevate serum total IgE (tIgE) and mouse mast cell protease 1 (MMCP1) after consecutive immunization for 5 weeks, but could induce Evans blue extravasation (local) and cause obvious hypothermia (systemic) after a single injection. Further study showed that alkaloids in Kushen, especially matrine, were responsible for CKI-induced IHRs. Mechanism study showed that various platelet-activating factor (PAF) receptor antagonists could significantly counter CKI-induced IHRs locally or systemically. In cell system, CKI was able to promote PAF production in a non-cell-selective manner. In cell lysate, the effect of CKI on PAF production became stronger and could be abolished by blocking de novo pathway. In conclusion, our study identifies, for the first time, that CKI is a PAF inducer. It causes non-immunologic IHRs, rather than IgE-dependent IHRs, by promoting PAF production through de novo pathway. Alkaloids in Kushen, especially matrine, are the prime culprits for IHRs. Our findings may provide a potential approach for preventing and treating CKI-induced IHRs.

Antagonizing astrocytic platelet activating factor receptor-neuroinflammation for total flavone of epimedium in response to cuprizone demyelination

Demyelinating diseases of the central nervous system are characterized by recurrent demyelination and progressive neurodegeneration, but there are no clinical drugs targeting myelin regeneration or improving functional disability in the treatment of multiple sclerosis. Total flavone of Epimedium (TFE) is the main active components of Epimedium, which exhibits the beneficial biological activities in the treatment of diseases, but there is no report in the treatment of demyelinating disorder. The purpose of this study was to explore the therapeutic potential and possible mechanism of TFE in the treatment of demyelination. The results showed that TFE efficiently improved the behavioural performance and histological demyelination in cuprizone (CPZ)-induced demyelinating model. In terms of action, TFE increased astrocytes enrichment in corpus callosum, striatum and cortex, and promoted astrocytes to express neurotrophic factors. Furthermore, the expression of platelet-activating factor receptor (PAFR) in astrocytes was induced by CPZ feeding and LPS stimulation, accompanied by the increase of inflammatory cytokines TNF-α,IL-6 and IL-1β. TFE declined the expression of PAFR, and inhibited inflammatory response. At the same time, TFE also antagonized PAFR activation and inflammatory response triggered by PAF, which further confirmed that TFE, as a new PAFR antagonist, inhibited the astrocyte-derived inflammatory response by antagonizing PAFR-neuroinflammation axis, thus contributing to myelin protection and regeneration.

Combined Therapy With Avastin, a PAF Receptor Antagonist and a Lipid Mediator Inhibited Glioblastoma Tumor Growth.

Glioblastoma multiforme (GBM) is an aggressive, highly proliferative, invasive brain tumor with a poor prognosis and low survival rate. The current standard of care for GBM is chemotherapy combined with radiation following surgical intervention, altogether with limited efficacy, since survival averages 18 months. Improvement in treatment outcomes for patients with GBM requires a multifaceted approach due to the dysregulation of numerous signaling pathways. Recently emerging therapies to precisely modulate tumor angiogenesis, inflammation, and oxidative stress are gaining attention as potential options to combat GBM. Using a mouse model of GBM, this study aims to investigate Avastin (suppressor of vascular endothelial growth factor and anti-angiogenetic treatment), LAU-0901 (a platelet-activating factor receptor antagonist that blocks pro-inflammatory signaling), Elovanoid; ELV, a novel pro-homeostatic lipid mediator that protects neural cell integrity and their combination as an alternative treatment for GBM. Female athymic nude mice were anesthetized with ketamine/xylazine, and luciferase-modified U87MG tumor cells were stereotactically injected into the right striatum. On post-implantation day 13, mice received one of the following: LAU-0901, ELV, Avastin, and all three compounds in combination. Bioluminescent imaging (BLI) was performed on days 13, 20, and 30 post-implantation. Mice were perfused for ex vivo MRI on day 30. Bioluminescent intracranial tumor growth percentage was reduced by treatments with LAU-0901 (43%), Avastin (77%), or ELV (86%), individually, by day 30 compared to saline treatment. In combination, LAU-0901/Avastin, ELV/LAU-0901, or ELV/Avastin had a synergistic effect in decreasing tumor growth by 72, 92, and 96%, respectively. Additionally, tumor reduction was confirmed by MRI on day 30, which shows a decrease in tumor volume by treatments with LAU-0901 (37%), Avastin (67%), or ELV (81.5%), individually, by day 30 compared to saline treatment. In combination, LAU-0901/Avastin, ELV/LAU-0901, or ELV/Avastin had a synergistic effect in decreasing tumor growth by 69, 78.7, and 88.6%, respectively. We concluded that LAU-0901 and ELV combined with Avastin exert a better inhibitive effect in GBM progression than monotherapy. To our knowledge, this is the first study that demonstrates the efficacy of these novel therapeutic regimens in a model of GBM and may provide the basis for future therapeutics in GBM patients.

The Platelet-Activating Factor Receptor's Association with the Outcome of Ovarian Cancer Patients and Its Experimental Inhibition by Rupatadine.

The platelet-activating factor receptor (PAFR) and its ligand (PAF) are important inflammatory mediators that are overexpressed in ovarian cancer. The receptor is an important player in ovarian cancer development. In this study, we aimed to evaluate the prognostic value of PAFR in epithelial ovarian cancer (EOC) and the potential use of its antagonist, rupatadine, as an experimental treatment. Tissue microarrays of ovarian cancer patients, most markedly those with a non-mucinous subtype, immunohistochemically overexpressed PAFR. Elevated cytoplasmic PAFR expression was found to significantly and independently impair patients’ overall and recurrence-free survival (OS: median 83.48 vs. 155.03 months; p = 0.022; RFS: median 164.46 vs. 78.03 months; p = 0.015). In vitro, the serous ovarian cancer subtypes especially displayed an elevated PAFR gene and protein expression. siRNA knockdown of PAFR decreased cell proliferation significantly, thus confirming the receptor’s protumorigenic effect on ovarian cancer cells. The clinically approved PAFR antagonist rupatadine effectively inhibited in vitro cell proliferation and migration of ovarian cancer cells. PAFR is a prognostic marker in ovarian cancer patients and its inhibition through rupatadine may have important therapeutic implications in the therapy of ovarian cancer patients.