Secretory Phospholipase Research Articles

Comparison of secretory acid proteinase, phospholipase activity, and slime production in Candida parapsilosis complex strains isolated from blood cultures and other clinical samples

Comparison of secretory acid proteinase, phospholipase activity, and slime production in Candida parapsilosis complex strains isolated from blood cultures and other clinical samples

Is There a Role for Inflammation in Contact Lens Discomfort?

The aim of this study was to examine the literature with respect to inflammation of the ocular surface and the presence of inflammatory mediators in the tear film during contact lens wear. The literature on contact lens discomfort that relates to signs of inflammation was searched. Reference was paid to the cardinal signs of inflammation (pain, heat, redness, and swelling) as well as the appearance of inflammatory mediators in the tear film during contact lens wear. Contact lens wear does induce discomfort, which is a mild form of pain, and wearing of lenses can induce increases in limbal and conjunctival redness. However, there is little evidence for a direct relationship between limbal or conjunctival redness and contact lens discomfort. Contact lenses may increase the temperature of the ocular surface by a small amount (≤2.1°C). Corneal or conjunctival swelling has not been associated with contact lens discomfort. Complement or kinin breakdown products or histamine in tears are not associated with contact lens discomfort. Cytokines are generally not related to discomfort, although nerve growth factor levels were increased in tears of symptomatics in one report. The presence of degraded lipids, leukotriene B4 and peroxidation products, and the enzyme secretory phospholipase A2 in tears has been associated with contact lens discomfort, and this area is worthy of further research. There have been only a few studies that have investigated a role for inflammation in contact lens-induced discomfort, and the strongest associations have been found with lipid degradation processes.

Neutralization of Inflammation by Inhibiting In vitro and In vivo Secretory Phospholipase A2 by Ethanol Extract of Boerhaavia diffusa L.

Background:Inflammation is a normal and necessary prerequisite to healing of the injured tissues. Inflammation contributes to all disease process including immunity, vascular pathology, trauma, sepsis, chemical, and metabolic injuries. The secretory phospholipase A2 (sPLA2) is a key enzyme in the production of pro-inflammatory mediators in chronic inflammatory disorders such as rheumatoid arthritis, coronary heart disease, diabetes, and asthma. The sPLA2 also contribute to neuroinflammatory disorders such as Parkinson's, Alzheimer's, and Crohn's disease.Aims:The present study aims to investigate the inhibition of human sPLA2 by a popular medicinal herb Boerhaavia diffusa Linn. as a function of anti-inflammatory activity.Materials and Methods:The aqueous and different organic solvents extracts of B. diffusa were prepared and evaluated for human synovial fluid, human pleural fluid, as well as Vipera russelli and Naja naja venom sPLA2 enzyme inhibition.Results:Among the extracts, the ethanol extract of B. diffusa (EEBD) showed the highest sPLA2 inhibition and IC50 values ranging from 17.8 to 27.5 μg. Further, antioxidant and lipid peroxidation activities of B. diffusa extract were checked using 2,2-diphenyl-1-picrylhydrazyl radical, thiobarbituric acid, and rat liver homogenate. The antioxidant activity of EEBD was more or less directly proportional to in vitro sPLA2 inhibition. Eventually, the extract was subjected to neutralize sPLA2-induced mouse paw edema and indirect hemolytic activity. The EEBD showed similar potency in both the cases.Conclusions:The findings suggest that the bioactive molecule/s from the EEBD is/are potentially responsible for the observed in vitro and in vivo sPLA2 inhibition and antioxidant activity.SUMMARY The present study aims to investigate the inhibition of human sPLA2 by a popular medicinal herb Boerhaavia diffusa Linn. as a function of anti inflammatory activity. Abbreviation Used: EEBD: Ethanolic extract of boerhaavia diffusa, sPLA2: Secretory phospholipase A2, HSF: Human synovial fluid, HPF: Human pleural fluid, VRV-PLA2-V: Vipera russelli phospholipase A2, NN-PLA2-I: Naja naja phospholipase A2.

Effects of Statins and Xuezhikang on the Expression of Secretory Phospholipase A2, Group IIA in Rat Vascular Smooth Muscle Cells.

Atherosclerosis is a multifactorial vascular disease characterized by formation of inflammatory lesions. Secretory phospholipase A2, group IIA (sPLA2-IIA) is involved in this process and plays a critical role. However, the exact role of sPLA2-IIA in cardiovascular inflammation is more complicated and remains unclear. Furthermore, both statins and Xuezhikang (XZK) are widely used in the prevention and treatment of cardiovascular disease risk because of their pleiotropic effects on the cardiovascular system. However, their effects on sPLA2-IIA are still controversial. We investigated the regulation of sPLA2-IIA by rat thoracic aorta smooth muscle cells (VSMCs) in culture. Cells were first incubated with IL-1β alone to induce expression of sPLA2-IIA and then treated with several concentrations of statins or XZK for different times in the absence or presence of IL-1β. We tested the expression of sPLA2-IIA, including sPLA2-IIA mRNA, protein, as well as activity. We found that statins or IL-1β increase the expression of sPLA2-IIA in VSMCs and the effect is based on a synergetic relationship between them. However, for the first time, we observed that XZK effectively reduces sPLA2-IIA expression in IL-1β-treated VSMCs. Our findings may shine a new light on the clinical use of XZK and statins in the prevention and treatment of atherosclerosis-related thrombosis.

Alteration of Lysophosphatidylcholine-Related Metabolic Parameters in the Plasma of Mice with Experimental Sepsis.

Plasma concentration of lysophosphatidylcholine (LPC) was reported to decrease in patients with sepsis. However, the mechanisms of sepsis-induced decrease in plasma LPC levels are not currently well known. In mice subjected to cecal ligation and puncture (CLP), a model of polymicrobial peritoneal sepsis, we examined alterations in LPC-related metabolic parameters in plasma, i.e., the plasma concentration of LPC-related substances (i.e., phosphatidylcholine (PC) and lysophosphatidic acid (LPA)), and activities or levels in the plasma of some enzymes that can be involved in the regulation of plasma LPC concentration (i.e., secretory phospholipase A2 (sPLA2), lecithin:cholesterol acyltransferase (LCAT), acyl-CoA:lysophosphatidylcholine acyltransferase (LPCAT), and autotaxin (ATX)), as well as plasma albumin concentration. We found that levels of LPC and albumin and enzyme activities of LCAT, ATX, and sPLA2 were decreased, whereas levels of PC, LPA, and LPCAT1-3 were increased in the plasma of mice subjected to CLP. Bacterial peritonitis led to alterations in all the measured LPC-related metabolic parameters in the plasma, which could potentially contribute to sepsis-induced decrease in plasma LPC levels. These findings could lead to the novel biomarkers of sepsis.

Decreased eicosapentaenoic acid levels in acne vulgaris reveals the presence of a proinflammatory state

This study aimed to determine circulating levels of polyunsaturated fatty acids (PUFAs), secretory phospholipase A2 (sPLA2), lipoprotein lipase (LPL) and measure circulating protein levels of angiopoietin-like protein 3 (ANGPTL3), ANGPTL4, cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2) in patients with acne vulgaris. Serum from 21 control subjects and 31 acne vulgaris patients were evaluated for levels of arachidonic acid (AA, C20:4n- 6), dihomo-gamma-linolenic acid (DGLA, C20:3n-6), eicosapentaenoic acid (EPA, C20:5n-3) and docosahexaenoic acid (DHA, C22:6n-3). PUFA levels were determined by an optimized multiple reaction monitoring (MRM) method using ultra fast-liquid chromatography (UFLC) coupled with tandem mass spectrometry (MS/MS). Lipid profile, routine biochemical and hormone parameters were assayed by standard kit methods Serum EPA levels were significantly decreased while AA/EPA and DGLA/EPA ratio were significantly increased in acne vulgaris patients compared to controls. Serum levels of AA, DGLA and DHA showed no significant difference while activity of sPLA2 and LPL were significantly increased in acne vulgaris compared to controls. Results of this study reveal the presence of a proinflammatory state in acne vulgaris as shown by significantly decreased serum EPA levels and increased activity of sPLA2, AA/EPA and DGLA/EPA ratio. Increased LPL activity in the serum of acne vulgaris patients can be protective through its anti-dyslipidemic actions. This is the first study reporting altered EPA levels and increased sPLA2 activity in acne vulgaris and supports the use of omega-3 fatty acids as adjuvant treatment for acne patients.

Secretory phospholipase A2 in the pathogenesis of acute dengue infection.

IntroductionPlatelet activating factor (PAF) is an important mediator of vascular leak in acute dengue. Phospholipase A2s (PLA2) are inflammatory lipid enzymes that generate and regulate PAF and other mediators associated with mast cells. We sought to investigate if mast cell activation and increases in secretory sPLA2s are associated with an increase in PAF and occurrence of dengue haemorrhagic fever (DHF).MethodsThe changes in the levels of mast cell tryptase, PAF and the activity of sPLA2 were determined throughout the course of illness in 13 adult patients with DHF, and 30 patients with dengue fever (DF).ResultsWe found that sPLA2 activity was significantly higher in patients with DHF when compared to those with DF, during the first 120 h of clinical illness. sPLA2 activity was significantly associated with PAF levels, which were also significantly higher in patients with DHF. Although levels of mast cell tryptase were higher in patients with DHF, the difference was not significant, and the levels were not above the reference ranges. sPLA2 activity significantly correlated with the degree of viraemia in patients with DHF but not in those with DF.ConclusionsPLA2 appears to play an important role in the pathogenesis of dengue. Since its activity is significantly increased during the early phase of infection in patients with DHF, this suggests that understanding the underlying mechanisms may provide opportunities for early intervention.

Synthesis, characterization and bioactivity studies of novel 1,3,4-oxadiazole small molecule that targets basic phospholipase A2 from Vipera russelli.

Secretory phospholipase A2 (sPLA2) is a key enzyme participating in the inflammatory cascade followed by the action of cyclooxygenase-2 and lipoxygenases. Therefore, inhibitors of sPLA2 could be used as potent anti-inflammatory agents to treat the early phase of inflammation. In this study, we have prepared the fenoprofen and ibuprofen analogs containing 1,3,4-oxadiazole nucleus and tested against Vipera russelli venom's basic sPLA2 (VRV-PL-VIIIa). Among the tested ligands 5(a-t),2-(2-chlorophenyl)-5-(1-(4-phenoxyphenyl) ethyl)-1,3,4-oxadiazole (5m) inhibited the catalytic activity of VRV-PL-VIIIa with an IC50 value of 11.52µM. Biophysical studies revealed that the 5m quenches the intrinsic fluorescence of VRV-PL-VIIIa, in a concentration dependent manner. Also, the compound 5m affected VRV-PL-VIIIa conformation, which was observed by circular dichroism spectra that recorded the prominent shift in the α-helix peak and the random coil formation of VRV-PL-VIIIa. Further, molecular docking analysis revealed that the compound 5m possess strong hydrophobic interactions at catalytic triad region of the VRV-PL-VIIIa. Evident to in vitro and in silico studies, 5m strongly inhibited the hemolysis of red blood cells. Our in vivo pharmacological studies revealed that the compound 5m inhibited the edematogenic activity of VRV-PL-VIIIa inmouse foot pad. Additionally, the 5m inhibited VRV-PL-VIIIa-induced myotoxicity and lung hemorrhage in mice. Overall, our ADMET results depicted that 5m possess better druggable property. Thus, this study explored the new fenoprofen and ibuprofen analog 5m as the lead-structure that serves as an anti-inflammatory agent.

Synthesis, Antiphospholipase A₂, Antiprotease, Antibacterial Evaluation and Molecular Docking Analysis of Certain Novel Hydrazones.

Some novel hydrazone derivatives 6a–o were synthesized from the key intermediate 4-Chloro-N-(2-hydrazinocarbonyl-phenyl)-benzamide 5 and characterized using IR, 1H-NMR, 13C-NMR, mass spectroscopy and elemental analysis. The inhibitory potential against two secretory phospholipase A2 (sPLA2), three protease enzymes and eleven bacterial strains were evaluated. The results revealed that all compounds showed preferential inhibition towards hGIIA isoform of sPLA2 rather than DrG-IB with compounds 6l and 6e being the most active. The tested compounds exhibited excellent antiprotease activity against proteinase K and protease from Bacillus sp. with compound 6l being the most active against both enzymes. Furthermore, the maximum zones of inhibition against bacterial growth were exhibited by compounds; 6a, 6m, and 6o against P. aeruginosa; 6a, 6b, 6d, 6f, 6l, 6m, 6n, and 6o against Serratia; 6k against S. mutans; and compounds 6a, 6d, 6e, 6m, and 6n against E. feacalis. The docking simulations of hydrazones 6a–o with GIIA sPLA2, proteinase K and hydrazones 6a–e with glutamine-fructose-6-phosphate transaminase were performed to obtain information regarding the mechanism of action.

Elevated Type II Secretory Phospholipase A2 Increases the Risk of Early Atherosclerosis in Patients with Newly Diagnosed Metabolic Syndrome.

A critical association between type II secretory phospholipase A2 (sPLA2-IIa) and established atherosclerotic cardiovascular disease has been demonstrated. However, the contribution of sPLA2-IIa to early atherosclerosis remains unknown. This study investigated the association between early-stage atherosclerosis and sPLA2-IIa in metabolic syndrome (MetS) patients. One hundred and thirty-six MetS patients and 120 age- and gender-matched subjects without MetS were included. Serum sPLA2-IIa protein levels and activity were measured using commercial kits. Circulating endothelial activation molecules (vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), E-selectin, and P-selectin), and carotid intima-media thickness (cIMT), were measured as parameters of vascular endothelial dysfunction and early atherosclerosis. MetS patients exhibited significantly higher sPLA2-IIa protein and activity levels than the controls. Both correlated positively with fasting blood glucose and waist circumference in MetS patients. Additionally, MetS patients exhibited strikingly higher levels of endothelial activation molecules and increased cIMT than controls. These levels correlated positively with serum sPLA2-IIa protein levels and activity. Moreover, multivariate analysis showed that high sPLA2-IIa protein and activity levels were independent risk factors of early atherosclerosis in MetS patients. This study demonstrates an independent association between early-stage atherosclerosis and increased levels of sPLA2-IIa, implying that increased sPLA2-IIa may predict early-stage atherosclerosis in MetS patients.

Lung Lavage and Surfactant Replacement During Ex Vivo Lung Perfusion for Treatment of Gastric Acid Aspiration–Induced Donor Lung Injury

Ex vivo lung perfusion (EVLP) provides opportunities to treat injured donor lungs before transplantation. We investigated whether lung lavage, to eliminate inflammatory inhibitory components, followed by exogenous surfactant replacement, could aid lung recovery and improve post-transplant lung function after gastric aspiration injury. Gastric acid aspiration was induced in donor pigs, which were ventilated for 6 hours to develop lung injury. After retrieval and 10 hours of cold preservation, EVLP was performed for 6 hours. The lungs were randomly divided into 4 groups (n = 5, each): (1) no treatment (control), (2) lung lavage, (3) surfactant administration, and (4) lung lavage, followed by surfactant administration. After another 2-hour period of cold preservation, the left lung was transplanted and reperfused for 4 hours. Physiologic lung function significantly improved after surfactant administration during EVLP. The EVLP perfusate from the lavage + surfactant group showed significantly lower levels of interleukin (IL)-1β, IL-6, IL-8, and secretory phospholipase A2. Total phosphatidylcholine was increased, and minimum surface tension was recovered to normal levels (≤5 mN/m) in the bronchioalveolar fluid after surfactant administration. Lysophosphatidylcholine in bronchioalveolar fluid was significantly lower in the lavage + surfactant group than in the surfactant group. Post-transplant lung function was significantly better in the lavage + surfactant group compared with all other groups. Lung lavage, followed by surfactant replacement during EVLP, reduced inflammatory mediators and prevented hydrolysis of phosphatidylcholine, which contributed to the superior post-transplant function in donor lungs with aspiration injury.

Activity-based targeting of secretory phospholipase A2 enzymes: A fatty-acid-binding-protein assisted approach

Syntheses and enzymological characterization of fluorogenic substrate probes targeting secretory phospholipase A2 (sPLA2) for detection and quantitative assays are presented. Three fluorogenic phosphatidylcholine analogs PC-1, PC-2, and PC-3 each containing the duo of 7-mercapto-4-methyl-coumarin fluorophore and 2,4-dinitroanaline quencher on either tail were synthesized from (R)-3-amino-1,2-propanediol and R-(-)-2,2-dimethyl-1,3-dioxolane-4-methanol. These small reporter groups are advantageous in preserving natural membrane integrity. Phosphocholine was incorporated into the sn-3 position of the glycerol backbone. Acyl amino group at the sn-1 position in PC-1 and PC-2 is meant to block sPLA1. The sn-1 and sn-2 positions of the glycerol backbone in PC-1 have a quencher terminated 12-carbon chain and fluorophore terminated 11-carbon chain respectively. PC-2 has a quencher terminated 3-carbon chain at the sn-2 and chain terminating fluorescent reporter at the sn-1 positions. PC-3 resembles PC-1 except for an ester instead of amide at the sn-1 position, because of which it is more similar to natural phospholipids than PC-1. It was designed to elucidate the effect of replacing the ester group with amide by comparing its hydrolysis rate with that of PC-1. Design principles apply to synthesis of other labeled phospholipids. Enzymological characterization using bee-venom sPLA2 was performed by a fatty-acid-binding-protein fluorescence assay and by pH-Stat method in which the amount of fatty acid released by hydrolysis is given by the amount of base required to maintain a constant pH of 8.0. Hydrolytic activity toward PC-1 and PC-3 were each about 238±25μmol/mg/min and 537μmol/mg/min on unmodified phospholipid. Ester to amide change did not affect hydrolysis rates. Activity toward PC-2 was about 45-μmol/mg/min. PC-1 and PC-3 show potential for targeted real-time spectrophotometric assay of sPLA2.

Carriers of the PCSK9 R46L Variant Are Characterized by an Antiatherogenic Lipoprotein Profile Assessed by Nuclear Magnetic Resonance Spectroscopy-Brief Report.

Carriers of the PCSK9 (proprotein convertase subtilisin/kexin 9) R46L genetic variant (rs11591147) are characterized by low levels of low-density lipoprotein cholesterol and a decreased risk of cardiovascular disease. We studied the impact of the R46L variant on lipoprotein size and composition. Lipoprotein size and composition were measured by nuclear magnetic resonance spectroscopy in 2373 participants of the EPIC (European Prospective Investigation into Cancer and Nutrition)-Norfolk study. After adjusting for age, sex, and cardiovascular disease status, carriers of the R46L variant (n=77) were characterized by lower concentrations of very low-density lipoprotein particles (85.8±26.2 versus 99.0±33.3 nmol/L; P<0.001), low-density lipoprotein particles (1479.7±396.8 versus 1662.9±458.3 nmol/L; P<0.001), and lipoprotein(a) (11.1 [7.2-28.6] versus 12.4 [6.7-29.1] mg/dL; P<0.001) compared with noncarriers. Total high-density lipoprotein particle and very low-density lipoprotein, low-density lipoprotein, and high-density lipoprotein particle sizes were comparable in carriers and noncarriers. Carriers were characterized by lower secretory phospholipase A2 (4.2±0.9 versus 4.6±1.3 nmol/mL/min; P=0.004) and lipoprotein-associated phospholipase A2 activity (47.5±14.1 versus 52.4±16.2 nmol/mL/min; P=0.02) compared with noncarriers. Results of this study suggest that carriers of the PCSK9 R46L genetic variant have lower very low-density lipoprotein and low-density lipoprotein particle concentrations, lower lipoprotein(a) levels, and lower secretory phospholipase A2 and lipoprotein-associated phospholipase A2 activity compared with noncarriers.

Novel Dual Inhibitors of Secretory Phospholipase A2 and Sphingomyelin Synthase: Design, Synthesis and Evaluation

Novel Dual Inhibitors of Secretory Phospholipase A2 and Sphingomyelin Synthase: Design, Synthesis and Evaluation

Anti-inflammatory and antioxidative effects of six pentacyclic triterpenes isolated from the Mexican copal resin of Bursera copallifera.

Background Bursera copallifera (Burseraceae) releases a resin known as “copal ancho” which has been used, since pre-Colombian times, as ceremonially burned incense and to treat tooth ache, tumors, arthritis, cold, cough, and various inflammatory conditions; however, its anti-inflammatory potential is poorly studied. The aim of the present study was to isolate, quantify, and to investigate the anti-inflammatory activity of triterpene compounds isolated from the copal resin of B. copallifera.MethodsThe constituents present in the total resin of B. copallifera were obtained by successive chromatographic procedures, and quantitative analysis was performed by High Performance Liquid Chromatography (HPLC). Anti-inflammatory effects of the isolated triterpenes were investigated to determine their inhibitory effects on phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced edema in mice, viability and nitric oxide (NO) production inhibition on lipopolysaccharide (LPS)-activated RAW 264.7 macrophages, and inhibition of cyclooxygenase (COX)-1, COX-2 and secretory Phospholipase A2 (sPLA2) activities in vitro.ResultsQuantitative phytochemical analysis of the copal resin showed the presence of six pentacyclic triterpenes of which, 3-epilupeol (59.75 % yield) and α-amyrin (21.1 % yield) are the most abundant. Among the isolated triterpenes, 3-epilupeol formiate (Inhibitory Concentration 50 % (IC50) = 0.96 μmol), α.amyrin acetate (IC50 = 1.17 μmol), lupenone (IC50 = 1.05 μmol), and 3-epilupeol (IC50 = 0.83 μmol) showed marked inhibition of the edema induced by TPA in mice. α-amyrin acetate and 3-epilupeol acetate, at 70 μM, also inhibited the activity of COX-2 by 62.85 and 73.28 % respectively, while α-amyrin and 3-epilupeol were the best inhibitors of the production of NO in LPS-activated RAW 264.7 cells with IC50 values of 15.5 and 8.98 μM respectively, and did not affected its viability. All compounds moderately inhibited the activity of PLA2.ConclusionsThis work supports the folk use of B. copallifera and provides the basis for future investigations about the therapeutic use of this resin in treating inflammation.

Effect of inflammation on HDL structure and function.

Studies have shown that chronic inflammatory disorders, such as rheumatoid arthritis, systemic lupus erythematosus, and psoriasis are associated with an increased risk of atherosclerotic cardiovascular disease. The mechanism by which inflammation increases cardiovascular disease is likely multifactorial but changes in HDL structure and function that occur during inflammation could play a role. HDL levels decrease with inflammation and there are marked changes in HDL-associated proteins. Serum amyloid A markedly increases whereas apolipoprotein A-I, lecithin:cholesterol acyltransferase, cholesterol ester transfer protein, paraoxonase 1, and apolipoprotein M decrease. The exact mechanism by which inflammation decreases HDL levels is not defined but decreases in apolipoprotein A-I production, increases in serum amyloid A, increases in endothelial lipase and secretory phospholipase A2 activity, and decreases in lecithin:cholesterol acyltransferase activity could all contribute. The changes in HDL induced by inflammation reduce the ability of HDL to participate in reverse cholesterol transport and protect LDL from oxidation. During inflammation multiple changes in HDL structure occur leading to alterations in HDL function. In the short term, these changes may be beneficial resulting in an increase in cholesterol in peripheral cells to improve host defense and repair but over the long term these changes may increase the risk of atherosclerosis.

Biomarkers of atherosclerotic plaque vulnerability and their clinical significance

Inflammatory reaction plays a crucial role in the occurence and development of atherosclerosis. Both basic and clinical trials have provided evidence that the expression of inflammatory biomarkers are closely related with the degree of atherosclerosis. Treatment towards inflammatory factors would bring benefit to atherosclerotic patients. This review highlighted the mechanistic rationale and specific therapies targeting traditional and novel inflammatory biomarkers, including C-reactive protein (CRP), interleukin-17 (IL-17), secretory phospholipase A2 (sPLA2), lipoprotein-associated phospholipase A2 (Lp-PLA2), endoglin, chemokine receptor and 5-lipoxygenase (5-LO), so as to review its mechanism of action and treatment prospect. DOI: 10.3969/j.issn.1672-6731.2016.09.004

Anti-inflammatory trends of new benzimidazole derivatives.

In present study, the anti-inflammatory activities of a new series of benzimidazole derivatives were studied, investigating their inhibition of secretory phospholipase A2, lipoxygenase, COXs and lipopolysaccharide-induced secretion of TNF-α and IL-6 in mouse RAW264.7 macrophages. Synthesized compounds effectively inhibited proinflammatory enzymes and cytokines. A strong inhibition of secretory phospholipases A2 was exhibited by benzimidazole derivatives with trifluoromethyl and methoxy substitutions at position 4 of attached phenyl, whereas compound 8 containing pyridine ring substituted with amino group showed very potent 5-lipoxygenase inhibition. Molecular docking experiments were carried out to elucidate the molecular basis of the observed inhibitory activities.

Association of type II secretory phospholipase A2 and surfactant protein D with the pulmonary oxygenation potential in patients with septic shock during polymyxin-B immobilized fiber-direct hemoperfusion.

This study was undertaken to analyze the association of type II secretory phospholipase A2 (sPLA2 -II) and surfactant protein D (SP-D) with the pulmonary oxygenation potential in patients with septic shock during polymyxin-B immobilized fiber-direct hemoperfusion (PMX-DHP). The study was conducted in 25 patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). PMX-DHP lowered the blood endotoxin level in all patients. Following PMX-DHP, there were decreases from day 0 → day 1 → day 2 in both the mean plasma sPLA2 -II level (340 → 260 → 189 ng/mL) and plasma SP-D level (483 → 363 → 252 ng/mL). The PaO2/FiO2 ratio (P/F ratio) rose (210 → 237 → 262) in all patients. Upon the onset of ALI or ARDS, there was a significant negative correlation between the sPLA2 -II level and the P/F ratio. Furthermore, there was a significant positive correlation between the sPLA2 -II and TNF-α levels. The results suggest that as the blood endotoxin levels were lowered by the PMX-DHP, the inflammatory reactions were suppressed, with suppressed formation of sPLA2 -II and improved pulmonary oxygenation potential. The results also suggested possible involvement of TNF-α in the production of sPLA2 -II.

Celastrol modulates inflammation through inhibition of the catalytic activity of mediators of arachidonic acid pathway: Secretory phospholipase A2 group IIA, 5-lipoxygenase and cyclooxygenase-2

Elevated production of arachidonic acid (AA)-derived pro-inflammatory eicosanoids due to the concerted action of secretory phospholipase A2 group IIA (sPLA2IIA), 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2) is a common feature of many inflammatory disorders. Hence, modulation of the bioactivity of these 3 enzymes is an important strategy to control inflammation. However, the failure of drugs specific for an individual enzyme (sPLA2IIA-, 5-LOX- or COX-2) and the success of 5-LOX/COX-2 dual inhibitors in effectively controlling inflammation in clinical trials prompted us to evaluate a common inhibitor for sPLA2IIA, 5-LOX and COX-2 enzymes. Celastrol, a quinone methide triterpene, was selected in this regard through molecular docking studies. We provide the first evidence for celastrol’s ability to inhibit the catalytic activity of sPLA2IIA, 5-LOX and COX-2 enzymes. Celastrol significantly inhibited the catalytic activity of sPLA2IIA (IC50=6μM) in vitro, which is independent of substrate and calcium concentration. In addition, celastrol inhibited the catalytic activities of 5-LOX (IC50=5μM) and COX-2 (IC50=20μM) in vitro; sPLA2IIA-induced edema and carrageenan-induced edema in mice; and lipopolysaccharide-stimulated production of PGE2 in human neutrophils. Thus, celastrol modulates inflammatory responses by targeting multiple enzymes of AA pathway.