α-Hederin inhibits the platelet activating factor-induced metastasis of HCC cells through disruption of PAF/PTAFR axis cascaded STAT3/MMP-2 expression.

Metastasis remains a crucial obstacle to the clinical treatment of hepatocellular carcinoma (HCC). Investigating the potential anti-tumor compounds from medicinal herb against HCC metastasis is of particular interest. As a triterpenoid saponin, α-Hederin has been reported to exhibit cytotoxicity for diverse cancer cell lines by inducing mitochondrial related apoptosis or autophagic cell death. Nevertheless, little is known about the inhibitory effect of α-Hederin on the metastasis of HCC and its underlying mechanisms. Here, we integrated well-established target prediction webtool and molecular docking methods to predict the potential targets for α-Hederin, and finally focused on PTAFR, the receptor for platelet-activating factor (PAF). Activation of PAF/PTAFR pathways has been reported to be contribution to the initiation and progression of cancer. We showed for the first time that non-cytotoxic concentration of α-Hederin inhibited cell migration and invasion induced by PAF in HCC cells, as well as lung metastasis in vivo. Moreover, we demonstrated α-Hederin reduced the PAF-induced matrix metalloproteinase-2 expression through inhibiting the activation of STAT3 in PAF stimulated HCC cells. These findings suggest that α-Hederin functions as a prospective inhibitor of PTAFR and may be utilized as an optional candidate for treatment of HCC.

Bioactive Lipids of Marine Microalga Chlorococcum sp. SABC 012504 with Anti-Inflammatory and Anti-Thrombotic Activities.

Microalgae are at the start of the food chain, and many are known producers of a significant amount of lipids with essential fatty acids. However, the bioactivity of microalgal lipids for anti-inflammatory and antithrombotic activities have rarely been investigated. Therefore, for a sustainable source of the above bioactive lipids, the present study was undertaken. The total lipids of microalga Chlorococcum sp., isolated from the Irish coast, were fractionated into neutral-, glyco-, and phospho-lipids, and were tested in vitro for their anti-inflammatory and antithrombotic activities. All tested lipid fractions showed strong anti-platelet-activating factor (PAF) and antithrombin activities in human platelets (half maximal inhibitory concentration (IC50) values ranging ~25-200 µg of lipid) with the highest activities in glyco- and phospho-lipid fractions. The structural analysis of the bioactive lipid fraction-2 revealed the presence of specific sulfoquinovosyl diacylglycerols (SQDG) bioactive molecules and the HexCer-t36:2 (t18:1/18:1 and 18:2/18:0) cerebrosides with a phytosphingosine (4-hydrosphinganine) base, while fraction-3 contained bioactive phosphatidylcholine (PC) and phosphatidylethanolamine (PE) molecules. These novel bioactive lipids of Chlorococcum sp. with putative health benefits may indicate that marine microalgae can be a sustainable alternative source for bioactive lipids production for food supplements and nutraceutical applications. However, further studies are required towards the commercial technology pathways development and biosafety analysis for the use of the microalga.

Human mesenchymal stem cells in the tumour microenvironment promote ovarian cancer progression: the role of platelet-activating factor.

BACKGROUND: The tumour microenvironment conferred by mesenchymal stem cells (MSCs) plays a key role in tumour development and progression. We previously determined that platelet-activating factor receptor (PAFR) was overexpressed in ovarian cancer cells (OCCs) and that PAF can promote ovarian cancer progression via PAF/PAFR-mediated inflammatory signalling pathways. Evidence suggests that MSCs can secrete high concentrations of PAF. Here, we investigated the role of PAF/PAFR signalling in the microenvironment mediated by MSCs and OCCs and its effect on cancer progression. METHODS: The PAF concentrations in the culture media of MSCs, OCCs and co-cultured MSCs and OCCs were determined by ELISA. The effects of MSCs on OCCs in vitro were assessed on cells treated with conditioned medium (CM). The expression and phosphorylation of key proteins in the PAF/PAFR signalling pathway were evaluated. In vivo, MSCs/RFP and SKOV3 cells were co-administered at different proportions to nude mice by interscapular injection. Mice in the WEB2086 group were intraperitoneally injected with the PAFR antagonist WEB2086 at a dose of 1 mg/kg.d for the duration of the animal experiments. Tumour progression was observed, and the weight and survival time of mice were measured. The PAF concentration in peripheral and tumour site blood was determined by ELISA. RESULTS: High concentrations of PAF were detected in CM from MSCs and MSCs co-cultured with OCCs. Both types of medium promoted non-mucinous OCC proliferation and migration but had no effect on mucinous-type OCCs. These effects could be blocked by PAFR inhibitors. The expression and phosphorylation of key proteins in the PAF/PAFR pathway significantly increased upon treatment with PAF and MSC-CM. In vivo, the tumour volume was larger following co-injection of SKOV3 cells and MSCs/RFP than following injection of SKOV3 cells alone. The tumour-promoting effect of MSCs/RFP was blocked by the PAFR antagonist WEB2086. Serum PAF concentrations significantly increased in co-injected mice. CONCLUSION: Our results suggest that the tumour-promoting effect of MSCs on OCCs via their cross-talk in the tumour microenvironment was, at least in part, mediated by the PAF/PAFR pathway, suggesting a new target for the treatment of ovarian cancer.

Tetrahydrobenzofuran-6(2 H)-one Neolignans from Ocotea heterochroma: Their Platelet Activating Factor (PAF) Antagonistic Activity and in Silico Insights into the PAF Receptor Binding Mode.

Three new tetrahydrobenzofuran-6(2 H)-one-type neolignans, heterochromins A-C (1-3), along with a bicyclo[3.2.1]octane neolignan, cinerin C (4), were isolated from an ethanol extract from the leaves of Ocotea heterochroma, a native plant growing in the Colombo-Ecuadorian region of the Andes. The chemical structures of 1-3 were elucidated by spectroscopic methods. The platelet activating factor (PAF) antagonistic activity was tested in vitro for these compounds. Additionally, their binding mode to the PAF receptor was studied by molecular docking and molecular dynamics simulations in order to rationalize such activity. Heterochromin A (1) was found to be a potent PAF antagonist with a favorable molecular profile for interacting with the PAF receptor binding site.

Human pharmacokinetics of ginkgo terpene lactones and impact of carboxylation in blood on their platelet-activating factor antagonistic activity.

Terpene lactones are a class of bioactive constituents of standardized preparations of Ginkgo biloba leaf extract, extensively used as add-on therapies in patients with ischemic cardiovascular and cerebrovascular diseases. This investigation evaluated human pharmacokinetics of ginkgo terpene lactones and impact of their carboxylation in blood. Human subjects received oral YinXing-TongZhi tablet or intravenous ShuXueNing, two standardized ginkgo preparations. Their plasma protein-binding and platelet-activating factor antagonistic activity were assessed in vitro. Their carboxylation was assessed in phosphate-buffered saline (pH 7.4) and in human plasma. After dosing YinXing-TongZhi tablet, ginkgolides A and B and bilobalide exhibited significantly higher systemic exposure levels than ginkgolides C and J; after dosing ShuXueNing, ginkgolides A, B, C, and J exhibited high exposure levels. The compounds' unbound fractions in plasma were 45-92%. Apparent oral bioavailability of ginkgolides A and B was mostly >100%, while that of ginkgolides C and J was 6-15%. Bilobalide's bioavailability was probably high but lower than that of ginkgolides A/B. Terminal half-lives of ginkgolides A, B, and C (4-7 h) after dosing ShuXueNing were shorter than their respective values (6-13 h) after dosing YinXing-TongZhi tablet. Half-life of bilobalide after dosing the tablet was around 5 h. Terpene lactones were roughly evenly distributed in various body fluids and tissues; glomerular-filtration-based renal excretion was the predominant elimination route for the ginkgolides and a major route for bilobalide. Terpene lactones circulated as trilactones and monocarboxylates. Carboxylation reduced platelet-activating factor antagonistic activity of ginkgolides A, B, and C. Ginkgolide J, bilobalide, and ginkgo flavonoids exhibited no such bioactivity. Collectively, differences in terpene lactones' exposure between the two preparations and influence of their carboxylation in blood should be considered in investigating the relative contributions of terpene lactones to ginkgo preparations' therapeutic effects. The results here will inform rational clinical use of ginkgo preparations.

Anti-platelet effects of vitamin supplements in age-related macular degeneration: an in vitro study.

OBJECTIVE: The purpose of this experimental study was to investigate the role of vitamin supplements (Ocuvite, Vitalux Omega, and Nutrof Total) as possible inhibitors of the onset of age-related macular degeneration (AMD). MATERIALS AND METHODS: The anti-aggregating effect of each vitamin was determined against four accumulative factors namely, platelet activating factor (PAF), adenosine diphosphate (ADP), thrombin receptor-activating peptide (TRAP), and arachidonic acid (AA) in the platelet rich plasma (PRP) of healthy volunteers. RESULTS: Ocuvite, Vitalux Omega, and Nutrof Total were more potent inhibitors against PAF and ADP compared to TRAP and AA. Among the three vitamins, Nutrof Total displayed more potent inhibitions against TRAP and AA, while against PAF and ADP all the three vitamins revealed similar IC50 values. CONCLUSIONS: The vitamins Ocuvite, Vitalux Omega, and Nutrof Total have anti-aggregating effects and therefore can be used against AMD in healthy volunteers.

Stereochemistry- and concentration-dependent effects of phosphatidylserine enrichment on platelet function.

Platelets are small (1-2µm in diameter), circulating anuclear cell fragments with important roles in hemostasis and thrombosis that provide an excellent platform for studying the role of membrane components in cellular communication. Platelets use several forms of communication including exocytosis of three distinct granule populations, formation of bioactive lipid mediators, and shape change (allowing for adhesion). This work explores the role of stereochemistry and concentration of exogenous phosphatidylserine (PS) on platelet exocytosis and adhesion. PS, most commonly found in the phosphatidyl-l-serine (l-PS) form, is exposed on the outer leaflet of the cell membrane after the platelet is activated. Knowledge about the impact of exogenous phosphatidylserine on cell-to-cell communication is limited (particularly concentration and stereochemistry effects). This study found that platelets incubated in l-PS or phosphatidyl-d-serine (d-PS) are enriched to the same extent with their respective incubated PS. All levels of l-PS enrichment also showed an increase in platelet cholesterol, but only the 50µM d-PS incubation showed an increase in cholesterol. The uptake of d-PS induced the secretion of granules and manufactured platelet activating factor (PAF) in otherwise unstimulated platelets. The uptake of l-PS had a greater impact on platelet stimulation by decreasing both the amount of δ-granule secretion and the amount of PAF that was manufactured.

Bioactive chemical constituents from the root bark of Morus australis.

Two new pyranoflavonoids, morustralins A (1) and B (2), a new natural benzene derivative, one benzenoid (Z)-1-hydroxy-4-(2-nitroethenyl)benzene (3), and thirty known compounds were isolated and characterized from the root bark of Morus australis. The structures of the new compounds were established from spectroscopic and spectrometric analyses. Ten isolates (1-10) were examined for inhibitory effects on adenosine diphosphate (ADP)-, arachidonic acid (AA)-, and platelet-aggregating factor (PAF)-induced platelet aggregation. Among the tested compounds, compound 3 displayed the most significant inhibition of ADP- and AA-induced platelet aggregation with IC50 values of 9.76±5.54 and 9.81±2.7µM, respectively. In addition, eight purified compounds (3-10) were examined for inhibition of nitric oxide (NO) production in RAW 264.7 cells and six compounds (3-8) displayed significant inhibitory effects with IC50 values ranging from 2.1±0.3 to 6.3±0.6µM.

[Stroke, platelet activating factor and receptor antagonists].

Stroke is an acute cerebrovascular disease with high morbidity, disability and mortality. The prevention and treatment conditions for stroke is severe all over the world. Antiplatelet aggregation is an effective treatment. Platelet activation factor (PAF) is another important medium in mediating platelet aggregation, which plays an important role in the pathogenesis of stroke. In recent years, PAF receptor antagonists have attracted international attention in the field of stroke prevention and treatment. In this review, we would summarize the classification, mechanism and drug characteristics of PAF receptor antagonists in order to provide the valuable guidance and direction for clinical medicine and research.

Platelet Activating Factor (PAF) biosynthesis is inhibited by phenolic compounds in U-937 cells under inflammatory conditions.

Interleukin 1 beta (IL-1ß) induced platelet activating factor (PAF) synthesis in U-937 cells through stimulation of acetyl-CoA:lysoPAF-acetyltransferase (lyso PAF-AT) at 3 h and DTT-independentCDP-choline-1-alkyl-2-acetyl-sn-glycerol cholinophosphotransferase (PAF-CPT) at 0.5 h. The aim of this study was to investigate the effect of tyrosol (T), resveratrol (R) and their acetylated derivatives(AcDs) which exhibit enhanced bioavailability, on PAF synthesis in U-937 after IL-1ß stimulation. The specific activity of PAF enzymes and intracellular levels were measured in cell homogenates. T and R concentration capable of inducing 50% inhibition in IL-1ß effect on lyso PAF-AT was 48 µΜ ± 11 and 157 µΜ ± 77, for PAF-CPT 246 µΜ ± 61 and 294 µΜ ± 102, respectively. The same order of concentration was also observed on inhibiting PAF levels produced by IL-1ß. T was more potent inhibitor than R (p<0.05). AcDs of T retain parent compound inhibitory activity, while in the case of R only two AcDs retain the activity. The observed inhibitory effect by T,R and their AcDs, may partly explain their already reported beneficial role.

Protective effect of high concentration of BN52021 on retinal contusion in cat eyes.

BACKGROUND: Blunt injuries/contusion on eyes might cause retina blunt trauma. This study is to evaluate the protective function of BN52021 against retinal trauma. METHODS: A total of 70 cats, 6 months old, were divided into six groups: Group A to E (n = 12) and normal control (N) group (n = 10). The right eyes in Group A to E were contused. All experiments were performed under general anesthetization. Retrobulbar injections of medication in right eyes were performed. Cats were administrated with 0.5 mL of normal saline (NS), dimethyl sulphoxide, 0.2 g/L BN52021, 1 g/L BN52021 and 5 g/L BN52021, respectively. Cats in Group N were administrated with 0.5 mL of NS. Intraocular pressure (IOP), flash electroretinogram (ERG), and retinal nerve fiber layer (RNFL) thickness were measured. Hematoxylin and eosin (HE) staining and transmission electron microscope (TEM) were detected. RESULTS: No significant difference was observed in IOP levels among groups. Comparing with cats in Group N, those in Group A to E showed significant lower amplitudes of rod a- and b-waves (P < 0.05). Amplitudes of rod a- and b-waves were increased by administration of high concentration of BN52021 (≥ 1 g/L). Moreover, high concentration of BN52021 decreased the RNFL thickness increased by contusion. Axons in RNFL in Group E arranged neatly at 7 days after modeling. CONCLUSIONS: The degenerated axons caused by contusion were repaired by BN52021. The administration of high concentration of (≥ 1 g/L) BN52021 could partially repair retinal function in contused cat eyes.

Ginkgolide B Reduces the Degradation of Membrane Phospholipids to Prevent Ischemia/Reperfusion Myocardial Injury in Rats.

Platelet-activating factor (PAF), a bioactive phospholipid, plays an important role in the integrity of the cellular membrane structure, and is involved in the pathogenesis of myocardial ischemia/reperfusion (IR) injuries. In this study, we tested the hypothesis that blockage of PAF receptor by BN 52021 (Ginkgolide B) can prevent IR-induced degradation of the myocardial membrane phospholipid, and deterioration of the cardiac function. Rat hearts in situ were subjected to 5 min ischemia and followed by 10 min reperfusion. Cardiac performances during periods of ischemia and reperfusion were monitored, and the amount of membrane phospholipids was analyzed. Myocardial total phospholipids, phosphatidylcholine, and phosphatidylethanolamine were decreased significantly in ischemia-reperfusion rat hearts compared with those of sham-operated rat hearts. Degradation of the membrane phospholipid was accompanied by the deterioration of cardiac functions and increase in serum lactate dehydrogenase (LDH) activity. BN 52021 (15 mg/kg), given by intravenous infusion 10 min prior to the left anterior descending coronary artery occlusion, reduced IR-related degradation of the myocardial phospholipids, the activity of serum LDH, and was concomitant with improvement of cardiac function. Furthermore, we demonstrated that the production of PAF was increased and BN 52021 decreased cellular damage in cultured anoxic cardiomyocytes. These results indicated that PAF antagonist BN 52021 has a protective effect against IR-induced myocardial dysfunction and degradation of the membrane phospholipids.

Short, enantioselective total synthesis of chatancin.

An enantioselective total synthesis of the polycyclic diterpene (+)-chatancin, a potent PAF antagonist, is reported. Proceeding in seven steps from dihydrofarnesal, this synthetic route was designed to circumvent macrocyclization-based strategies to complex, cyclized cembranoids. The described synthesis requires only six chromatographic purifications, is high yielding, and avoids protecting-group manipulations. An X-ray crystal structure of this fragile marine natural product was obtained.

Effects of platelet-activating factor and its differential regulation by androgens and steroid hormones in prostate cancers.

BACKGROUND: Platelet-activating factor (PAF) is an arachidonic acid metabolite that plays an important role in cell proliferation, migration and neoangiogenesis, but whether it is involved in the progression of prostate cancer remains undiscovered. METHODS: Clinical prostate specimens were investigated with immunohistochemistry method and in vitro cell experiments referred to MTS cell proliferation assay, invasion and migration experiment, quantitative real-time RT-PCR assay, western blotting analysis and ELISA assay. RESULTS: Platelet-activating factor synthetase, lyso-PAF acetyl transferase (LPCAT1), increased significantly in castration-resistant prostate cancer (CRPC) specimens and CRPC PC-3 cells than that in controls. Intriguingly, PAF induced invasion and migration of PC-3 cells but not LNCaP cells. The PAF receptor antagonist inhibited proliferation of LNCaP and PC-3 cells. Dihydrotestosterone (DHT) treatment caused a decrease in LPCAT1 expression and PAF release in LNCaP cells, which could be blocked by androgen receptor antagonists. Finally, DHT increased LPCAT1 expression and PAF release in PC-3 cells in a Wnt/ß-catenin-dependent manner. CONCLUSION: For the first time, our data supported that PAF might play pivotal roles in the progression of prostate cancer, which might throw a new light on the treatment of prostate cancer and the prevention of the emergence of CRPC.

Rupatadine inhibits inflammatory mediator release from human laboratory of allergic diseases 2 cultured mast cells stimulated by platelet-activating factor.

BACKGROUND: Mast cells are involved in allergy and inflammation by the secretion of multiple mediators, including histamine, cytokines, and platelet-activating factor (PAF), in response to different triggers, including emotional stress. PAF has been associated with allergic inflammation, but there are no clinically available PAF inhibitors. OBJECTIVE: To investigate whether PAF could stimulate human mast cell mediator release and whether rupatadine (RUP), a dual histamine-1 and PAF receptor antagonist, could inhibit the effect of PAF on human mast cells. METHODS: Laboratory of allergic diseases 2 cultured mast cells were stimulated with PAF (0.001, 0.01, and 0.1 µmol/L) and substance P (1 µmol/L) with or without pretreatment with RUP (2.5 and 25 µmol/L), which was added 10 minutes before stimulation. Release of ß-hexosaminidase was measured in supernatant fluid by spectrophotoscopy, and histamine, interleukin-8, and tumor necrosis factor were measured by enzyme-linked immunosorbent assay. RESULTS: PAF stimulated a statistically significant release of histamine, interleukin-8, and tumor necrosis factor (0.001-0.1 µmol/L) that was comparable to that stimulated by substance P. Pretreatment with RUP (25 µmol/L) for 10 minutes inhibited this effect. In contrast, pretreatment of laboratory of allergic diseases 2 cells with diphenhydramine (25 µmol/L) did not inhibit mediator release, suggesting that the effect of RUP was not due to its antihistaminic effect. CONCLUSION: PAF stimulates human mast cell release of proinflammatory mediators that is inhibited by RUP. This action endows RUP with additional properties in treating allergic inflammation.

Anti-platelet-activating factor, antibacterial, and antiradical activities of lipids extract from silver carp brain.

BACKGROUND: Epidemiological studies have verified the protective role of fish lipids in cardiovascular diseases. However, the effects of fish lipids on health boost remain undefined. Large amounts of by-products, such as fish brain which contains high level of lipids, are produced with silver carp processing. Fish brain is rich in bioactive lipids which are overwhelmingly effective in preventing cardiovascular diseases. The aim of this study was to elucidate the pharmacological activities of silver carp brain lipids against diseases by inhibiting platelet-activating factor (PAF), suppressing bacterial growth and scavenging free radicals. METHODS: Total lipids (TL) were extracted from silver carp brain and separated into polar lipids (PL) and neutral lipids (NL). The capabilities of the lipid fractions in aggregating washed rabbit platelet or in inhibiting PAF-induced platelet aggregation were tested. Their antibacterial and antiradical activities were studied as well. RESULTS: The lipid fractions exhibited strong inhibitory activities, and the activity of TL was mainly attributed to NL. TL exhibited antibacterial activity towards Staphylococcus aureus, while NL managed to fight against S. aureus and Escherichia coli. PL excelled TL and NL in simultaneously suppressing the growths of Shigella dysenteriae and Salmonella typhi besides those of S. aureus and E. coli. The scavenging effect of PL on 2,2-diphenyl-1-picrylhydrazyl radical was considerably higher than those of TL and NL. CONCLUSION: The present study may help to explain the protective role of fish lipids against diseases and may be responsible for the effectiveness of fish brain in benefiting health.

Platelet activating factor in heart failure: potential role in disease progression and novel target for therapy.

Heart failure (HF) is a complex syndrome with cardiac, renal, neurohormonal and sympathetic nervous system's manifestations, the pathogenesis of which among others is connected to inflammation. PAF has local and systemic effects pertaining to HF progression since it causes a negative inotropic effect, it induces arrhythmias, it induces apoptosis and it is involved in inflammation and atherosclerosis. In the present review the role of PAF in HF will be thoroughly presented along with the relevant data on PAF enzymes and the potential role of PAF metabolic circuit as a novel pharmacological target.

Platelet-activating factor blockade inhibits the T-helper type 17 cell pathway and suppresses psoriasis-like skin disease in K5.hTGF-ß1 transgenic mice.

Platelet-activating factor (PAF), a potent biolipid mediator, is involved in a variety of cellular transduction pathways and plays a prominent role in inducing inflammation in different organs. We used K5.hTGF-ß1 transgenic mice, which exhibit an inflammatory skin disorder and molecular and cytokine abnormalities with strong similarities to human psoriasis, to study the pathogenic role of PAF. We found that injecting PAF into the skin of transgenic mice led to inflammation and accelerated manifestation of the psoriatic phenotype by a local effect. In contrast, injecting mice with PAF receptor antagonist PCA-4248 lowered the PAF level (most likely by depressing an autocrine loop) and neutrophil, CD68(+) cell (monocyte/macrophage), and CD3(+) T-cell accumulation in the skin and blocked progression of the psoriasis-like phenotype. This effect of PAF blockade was specific and similar to that of psoralen-UV-A and was paralleled by a decrease in abnormally elevated mRNA and/or protein levels of T-helper type 17 cell-related cytokines IL-17A, IL-17F, IL-23, IL-12A, and IL-6 and its transcription factor signal transducer and activator of transcription 3. In contrast, PCA-4248 treatment up-regulated mRNA levels of cyclooxygenase-2 and IL-10 in dorsal skin and release of IL-10 in serum and skin. Interfering with PAF may offer the opportunity to develop novel therapeutic strategies for inflammatory psoriasis and associated comorbidities, including metabolic syndrome and atherosclerosis, in which the IL-17 axis may be involved.

Lipoxin A4 inhibits platelet-activating factor inflammatory response and stimulates corneal wound healing of injuries that compromise the stroma.

Platelet-activating factor (PAF) is a bioactive lipid mediator with strong inflammatory properties. PAF induces the expression and activation of metalloproteinase-9 (MMP-9) in corneal epithelial cells and myofibroblasts, and delays epithelial wound healing in an organ culture system. Lipoxin A(4) (LXA(4)) is a lipid mediator involved in resolution of inflammation and cornea epithelial wound healing. We developed an in vivo mouse model of injury to the anterior stroma that is sustained by PAF and evaluated the action of LXA(4). In this model mice were treated with vehicle, PAF alone and in combination with PAF receptor antagonist LAU-0901 or LXA(4). Mice were euthanized 1, 2 and 7 days after injury and corneas were processed for histology (H&E staining) and immunofluorescence with antibodies for MMP-9, α-smooth muscle actin (α-SMA), fibronectin (FN) and neutrophil. Interleukin 1-α (IL-1α) and keratinocyte-derived chemokine (KC/CXCL1) were assayed by ELISA. Myeloperoxidase (MPO) activity was performed in corneal homogenates. In this in vivo model PAF inhibited epithelial wound healing that was blocked by the PAF receptor antagonist LAU-0901. Treatment with LXA(4) significantly reduced the injured area compared to PAF at 1 and 2 days of treatment. The strong stromal cell infiltration and MPO activity stimulated by PAF was also decreased with LXA(4) treatment. PAF increased MMP-9 and decreased FN expression compared to vehicle treatment and less α-SMA positive cells migrated to the wounded area. The PAF actions were reverted by LXA(4) treatment. The results demonstrated a powerful action of LXA(4) in protecting corneas with injuries that compromise the stroma by decreasing inflammation and increasing wound healing.

Noninvasive molecular imaging reveals role of PAF in leukocyte-endothelial interaction in LPS-induced ocular vascular injury.

Uveitis is a systemic immune disease and a common cause of blindness. The eye is an ideal organ for light-based imaging of molecular events underlying vascular and immune diseases. The phospholipid platelet-activating factor (PAF) is an important mediator of inflammation, the action of which in endothelial and immune cells in vivo is not well understood. The purpose of this study was to investigate the role of PAF in endothelial injury in uveitis. Here, we use our recently introduced in vivo molecular imaging approach in combination with the PAF inhibitors WEB 2086 (WEB) and ginkgolide B (GB). The differential inhibitory effects of WEB and GB in reducing LPS-induced endothelial injury in the choroid indicate an important role for PAF-like lipids, which might not require the PAF receptor for their signaling. P-selectin glycoprotein ligand-1-mediated rolling of mouse leukocytes on immobilized P-selectin in our autoperfused microflow chamber assay revealed a significant reduction in rolling velocity on the cells' contact with PAF. Rolling cells that came in contact with PAF rapidly assumed morphological signs of cell activation, indicating that activation during rolling does not require integrins. Our results show a key role for PAF in mediating endothelial and leukocyte activation in acute ocular inflammation. Our in vivo molecular imaging provides a detailed view of cellular and molecular events in the complex physiological setting.