Interleukin-1 enhances the ability of cultured human umbilical vein endothelial cells to oxidize linoleic acid

Limiting Injury During Saphenous Vein Graft Preparation For Coronary Arterial Bypass Prevents Metabolic Decompensation

Standard harvest and preparation of human saphenous vein (HSV) for autologous coronary and peripheral arterial bypass procedures is associated with injury and increased oxidative stress that negatively affect graft performance. In this study we investigated the global metabolomic profiles of HSV before (unprepared; UP) and after standard vein graft preparation (AP). AP-HSV showed impaired vasomotor function that was associated with increased oxidative stress, phospholipid hydrolysis and energy depletion that are characteristic of mechanical and chemical injury. A porcine model (PSV) was utilized to validate these metabolomic changes in HSV and to determine the efficacy of an improved preparation technique (OP) using pressure-regulated distension, a non-toxic vein marker, and graft storage in buffered PlasmaLyte solution in limiting metabolic decompensation due to graft preparation. Deficits in vasomotor function and metabolic signature observed in AP-PSV could be largely mitigated with the OP procedure. These findings suggest that simple strategies aimed at reducing injury during graft harvest and preparation represents a straightforward and viable strategy to preserve conduit function and possibly improve graft patency.

Oxylipid Profile of Low-Dose Aspirin Exposure: A Pharmacometabolomics Study

Background

While aspirin is a well‐established and generally effective anti‐platelet agent, considerable inter‐individual variation in drug response exists, for which mechanisms are not completely understood. Metabolomics allows for extensive measurement of small molecules in biological samples, enabling detailed mapping of pathways involved in drug response.

Methods and Results

We used a mass‐spectrometry‐based metabolomics platform to investigate the changes in the serum oxylipid metabolome induced by an aspirin intervention (14 days, 81 mg/day) in healthy subjects (n=156). We observed a global decrease in serum oxylipids in response to aspirin (25 metabolites decreased out of 30 measured) regardless of sex. This decrease was concomitant with a significant decrease in serum linoleic acid levels (−19%, P=1.3×10⁻⁵), one of the main precursors for oxylipid synthesis. Interestingly, several linoleic acid‐derived oxylipids were not significantly associated with arachidonic‐induced ex vivo platelet aggregation, a widely accepted marker of aspirin response, but were significantly correlated with platelet reactivity in response to collagen.

Conclusions

Together, these results suggest that linoleic acid‐derived oxylipids may contribute to the non‐COX1 mediated variability in response to aspirin. Pharmacometabolomics allowed for more comprehensive interrogation of mechanisms of action of low dose aspirin and of variation in aspirin response.

Increased cerebrospinal fluid cleaved tau protein (C-tau) levels suggest axonal damage in pediatric patients with brain tumors

OBJECTIVE

This study aims to determine if cerebrospinal fluid/serum cleaved tau protein and CSF 9-hydroxyoctadecadienoic acid levels, reflecting potential biomarkers of overall neuronal injury and lipid peroxidation, respectively, are elevated in brain tumor patients compared with controls.

DESIGN

This article is a prospective clinical observational study.

SETTING

This study is conducted at a tertiary-care children's hospital.

PATIENTS

Our participants are children younger than or equal to 18 years of age undergoing brain tumor surgery.

MEASUREMENTS AND MAIN RESULTS

During the study period, 26 consecutive patients newly diagnosed with brain tumors who met the inclusion criteria were prospectively enrolled. Baseline cerebrospinal fluid analysis of cleaved tau and 9-hydroxyoctadecadienoic acid were measured in 15 patients. Cerebrospinal fluid cleaved tau and 9-hydroxyoctadecadienoic acid levels were measured in 22 patients for post-surgery days 1 and 3. Serum cleaved tau levels were measured for 20 and 18 patients for post-surgery days 1 and 3, respectively. The presence of a brain tumor significantly increased the baseline cerebrospinal fluid cleaved tau levels but did not affect cerebrospinal fluid 9-hydroxyoctadecadienoic acid levels. Similarly, there was a significant increase in post-surgery day 1 cerebrospinal fluid cleaved tau levels from baseline (p = 0.01) and a trend toward significant decrease in post-surgery day 3 cerebrospinal fluid cleaved tau from day 1 (p = 0.07). 9-Hydroxyoctadecadienoic acid concentrations remained relatively constant over time with no differences noted between the control and brain tumor patients. There was a trend towards a significant association between cerebrospinal fluid cleaved tau levels and duration of symptoms (p = 0.07).

CONCLUSIONS

Cerebrospinal fluid cleaved tau levels in children with newly diagnosed brain tumors exhibit markedly elevated cerebrospinal fluid cleaved tau levels, suggesting axonal damage. This axonal injury does not seem to correlate with lipid peroxidation at least when as assessed by cerebrospinal fluid 9-hydroxyoctadecadienoic acid levels. There was no association found between the biomarkers and multiple independent variables obtained at pre- and post-tumor resection.

Influence of cardiovascular risk factors on levels of matrix metalloproteinases 2 and 9 in human abdominal aortic aneurysms

OBJECTIVE

To evaluate the influence of cardiovascular risk factors on levels of matrix metalloproteinases (MMP) 2 and 9 in human abdominal aortic aneurysms (AAA).

METHODS

Aortic samples were collected from patients who underwent AAA repair (n = 89). Patients were stratified according to the maximum transverse aorta diameter: small diameter (<55 mm), moderate diameter (55-69.9 mm) and large diameter (≥70 mm). Aortic walls were studied using real-time PCR and immunohistochemistry. MMP-2, MMP-9, α-actin, CD45, and CD68 transcript levels were determined relative to β-actin. Quantitative data were expressed as median (IQ-range).

RESULTS

No differences were found in MMP-2 expression between the patient groups, which was mainly associated with vascular smooth muscle cells (VSMC); however, MMP-9 displayed the maximum level in the moderate-diameter group, associated with infiltrating macrophages. Current smoking (CS) and renal insufficiency (RI) significantly increased local levels of MMP-2 (CS 349.5 [219.5-414.1] vs. no-CS 184.4 [100.0-320.5]; p < .008; RI 286.8 [189.6-410.8] vs. no-RI 177.3 [99.3-326.9]; p = .047). Nevertheless, after stepwise linear regression analysis only CS remained as an independent variable predicting local levels of MMP-2 (p = .002). No risk factors influenced local levels of MMP-9.

CONCLUSIONS

The results show that local levels of MMP-2, an important factor for AAA development, were increased in current smoking AAA patients. MMP-2 was mainly associated with VSMC. It is suggested that MMP-2 could contribute significantly to the increased AAA growth rate observed in current smoking patients. These findings support inclusion of smokers in screening for aneurysmal disease, and emphasize the need for more aggressive monitoring of aneurysmal disease outside the surgical range in patients who smoke at the time of diagnosis and in those who continue to smoke during follow-up.

Linoleic acid metabolite drives severe asthma by causing airway epithelial injury

Airway epithelial injury is the hallmark of various respiratory diseases, but its mechanisms remain poorly understood. While 13-S-hydroxyoctadecadienoic acid (13-S-HODE) is produced in high concentration during mitochondrial degradation in reticulocytes little is known about its role in asthma pathogenesis. Here, we show that extracellular 13-S-HODE induces mitochondrial dysfunction and airway epithelial apoptosis. This is associated with features of severe airway obstruction, lung remodeling, increase in epithelial stress related proinflammatory cytokines and drastic airway neutrophilia in mouse. Further, 13-S-HODE induced features are attenuated by inhibiting Transient Receptor Potential Cation Channel, Vanilloid-type 1 (TRPV1) both in mouse model and human bronchial epithelial cells. These findings are relevant to human asthma, as 13-S-HODE levels are increased in human asthmatic airways. Blocking of 13-S-HODE activity or disruption of TRPV1 activity attenuated airway injury and asthma mimicking features in murine allergic airway inflammation. These findings indicate that 13-S-HODE induces mitochondrial dysfunction and airway epithelial injury.

Quantitative metabolic profiling of lipid mediators

Lipids are heterogeneous biological molecules that possess multiple physiological roles including cell structure, homeostasis, and restoration of tissue functionality during and after inflammation. Lipid metabolism constitutes a network of pathways that are related at multiple biosynthetic hubs. Disregulation of lipid metabolism can lead to pathophysiological effects and multiple lipid mediators have been described to be involved in physiological processes, (e.g. inflammation). Accordingly, a thorough description of these pathways may shed light on putative relations in multiple complex diseases, including chronic obstructive pulmonary disease, asthma, Alzheimer's disease, multiple sclerosis, obesity, and cancer. Due to the structural complexity of lipids and the low abundance of many lipid mediators, mass spectrometry is the most commonly employed method for analysis. However, multiple challenges remain in the efforts to analyze every lipid subfamily. In this review, the biological role of sphingolipids, glycerolipids, oxylipins (e.g. eicosanoids), endocannabinoids, and N-acylethanolamines in relation to health and disease and the state-of-the-art analyses are summarized. The characterization and understanding of these pathways will increase our ability to examine for interrelations among lipid pathways and improve the knowledge of biological mechanisms in health and disease.

Interaction between head and neck squamous cell carcinoma cells and fibroblasts in the biosynthesis of PGE2

Prostaglandin (PG)E(2) is relevant in tumor biology, and interactions between tumor and stroma cells dramatically influence tumor progression. We tested the hypothesis that cross-talk between head and neck squamous cell carcinoma (HNSCC) cells and fibroblasts could substantially enhance PGE(2) biosynthesis. We observed an enhanced production of PGE(2) in cocultures of HNSCC cell lines and fibroblasts, which was consistent with an upregulation of COX-2 and microsomal PGE-synthase-1 (mPGES-1) in fibroblasts. In cultured endothelial cells, medium from fibroblasts treated with tumor cell-conditioned medium induced in vitro angiogenesis, and in tumor cell induced migration and proliferation, these effects were sensitive to PGs inhibition. Proteomic analysis shows that tumor cells released IL-1, and tumor cell-induced COX-2 and mPGES-1 were suppressed by the IL-1-receptor antagonist. IL-1α levels were higher than those of IL-1β in the tumor cell-conditioning medium and in the secretion from samples obtained from 20 patients with HNSCC. Fractionation of tumor cell-conditioning media indicated that tumor cells secreted mature and unprocessed forms of IL-1. Our results support the concept that tumor-associated fibroblasts are a relevant source of PGE(2) in the tumor mass. Because mPGES-1 seems to be essential for a substantial biosynthesis of PGE(2), these findings also strengthen the concept that mPGES-1 may be \a target for therapeutic intervention in patients with HNSCC.

Tumor cells induce COX-2 and mPGES-1 expression in microvascular endothelial cells mainly by means of IL-1 receptor activation

Prostaglandin (PG) E(2) plays a key role in immune response, tumor progression and metastasis. We previously showed that macrovessel-derived endothelial cells do not produce PGE(2) enzymatically because they do not express the inducible microsomal PGE-synthase-1 (mPGES-1). Nevertheless, differences between macro- and micro-vessel-derived endothelial cells regarding arachidonic acid (AAc) metabolism profile have been reported. The present work was conducted to evaluate the expression of PGE(2)-pathway-related enzymes in human microvascular endothelial cells (HMVEC) in culture and to test the hypothesis that the tumor cell-HMVEC cross talk could increase mPGES-1 expression in HMVEC. We treated HMVEC in culture with human recombinant IL-1β. IL-1β induced PGE(2) release and COX-2 and mPGES-1 expression in terms of mRNA and protein, determined by real-time PCR and immunoblotting, respectively. HMVEC constitutively expressed mPGES-2 and cytosolic PGES (cPGES) and the IL-1β treatment did not modify their expression. PGE(2) synthesized by HMVEC from exogenous AAc was linked to mPGES-1 expression. Immunohistochemistry analysis confirmed mPGES-1 expression in microvessels in vivo. COX-2 and mPGES-1 were also induced in HMVEC by the conditioned medium from two squamous head and neck carcinoma cell lines. Conditioned medium from tumor cell cultures contained several cytokines including the IL-1β and IL-1α. Tumor cell-induced COX-2 and mPGES-1 in HMVEC was strongly inhibited by the IL-1-receptor antagonist, indicating the important implication of IL-1 in this effect. HMVEC could therefore contribute directly to PGE(2) formed in the tumor. Our findings support the concept that mPGES-1 could be a target for therapeutic intervention in patients with cancer.

Cerebrospinal fluid cleaved-tau protein and 9-hydroxyoctadecadienoic acid concentrations in pediatric patients with hydrocephalus

OBJECTIVE

To ascertain if cerebrospinal fluid cleaved-tau protein and 9-hydroxyoctadecadienoic acid, reflecting potential biomarkers of overall neuronal injury and lipid peroxidation, respectively, are elevated in hydrocephalus patients compared with controls, and if cleaved-tau and 9-hydroxyoctadecadienoic acid levels correlate with each other.

DESIGN

Prospective clinical observational study.

SETTING

Tertiary-care children's hospital.

PATIENTS

Children younger than or equal to 18 yrs who underwent ventriculoperitoneal shunt placement or revision surgery for intrinsic hydrocephalus.

MEASUREMENTS AND MAIN RESULTS

During the study period 12 patients with intrinsic hydrocephalus required ventriculoperitoneal shunt placement or revision. Cerebrospinal fluid cleaved-tau levels were significantly elevated in patients with hydrocephalus (44.7 +/- 9.6 ng/mL, n = 11) compared with control patients (0.0 +/- 0.0 ng/mL, n = 9; p < 0.0001). Cleaved-tau levels correlated with patient age (r = .609, p = 0.047) and duration of symptoms (r = .755, p = 0.007). No significant difference in cerebrospinal fluid 9-hydroxyoctadecadienoic acid levels between patients with hydrocephalus (24.6 +/- 5.7, n = 8) and control patients (24.9 +/- 9.3 ng/mL, n = 7) was detected (p = 0.25). There was also no statistically significant correlation between 9-hydroxyoctadecadienoic acid levels and duration of symptoms (r = .668, p = 0.07), nor was there a significant correlation between 9-hydroxyoctadecadienoic acid levels and patient age (r = -.011, p > 0.10). There was no significant relationship between 9-hydroxyoctadecadienoic acid levels and signs of elevated intracranial pressure, nor was there a correlation between 9-hydroxyoctadecadienoic acid levels and cleaved-tau levels.

CONCLUSION

Children with hydrocephalus who have clinical signs of increased intracranial pressure and require ventriculoperitoneal shunt placement or revision exhibit markedly elevated cerebrospinal fluid cleaved-tau levels, suggesting evidence of axonal damage. However, this axonal injury does not seem to be associated with significant lipid peroxidation, at least as assessed by quantifying cerebrospinal fluid 9-hydroxyoctadecadienoic acid at a single, concurrent time point. The significant relationship between age and cerebrospinal fluid cleaved-tau levels suggest that brain injury associated with hydrocephalus may be more pronounced in older children.

Microsomal prostaglandin E synthase-1, which is not coupled to a particular cyclooxygenase isoenzyme, is essential for prostaglandin E(2) biosynthesis in vascular smooth muscle cells

BACKGROUND

Prostaglandin (PG) E(2) induces expression of matrix metalloproteinases and angiogenic factors, thereby contributing to plaque instability.

OBJECTIVE

To study the influence of cyclooxygenase (COX) and PGE synthase (PGES) isoenzyme expression on PGE(2) and PGI(2) biosynthesis in vascular smooth muscle cells (VSMC) in culture.

METHODS

Cells were treated with human recombinant IL-1beta over different periods of time. Expression of PGI synthase, and COX and PGES isoenzymes was determined by real-time reverse transcriptase polymerase chain reaction and immunoblotting. Biosynthesis of prostanoids from exogenous or endogenous substrate was analyzed by high-performance liquid chromatography or enzyme-immunoassay after incubation of cells with labeled arachidonic acid or thrombin, respectively.

RESULTS

Cytosolic PGES and microsomal PGES (mPGES) -1 and -2 were expressed in VSMC. PGES activity was mainly linked to mPGES-1. IL-1beta induced COX-2 and mPGES-1 with a different time course. VSMC ability to synthesize PGE(2) and PGI(2) fitted mPGES-1 and COX-2 expression, respectively. The ability of VSMC to produce PGI(2) was downregulated by mPGES-1 expression and was restored when mPGES-1 expression was silenced. Results from COX-1 and COX-2 silencing and selective inhibition showed that both COX-1 and COX-2 were involved in the biosynthesis of PGE(2) and their relative contribution depended on the time of incubation with IL-1beta.

CONCLUSIONS

mPGES-1 is the main PGES responsible for PGE(2) biosynthesis by VSMC and its induction downregulates VSMC ability to produce PGI(2.) These results support the concept that under inflammatory conditions VSMC could significantly contribute to plaque instability and that mPGES-1 may be a target for therapeutic intervention in patients with cardiovascular risk.

IL-1beta induces VEGF, independently of PGE2 induction, mainly through the PI3-K/mTOR pathway in renal mesangial cells

Vascular endothelial growth factor (VEGF) could play a relevant role in angiogenesis associated with chronic allograft nephropathy. Interleukin-1beta (IL-1beta) has a key role in inflammatory response. It induces prostaglandin (PG) E2, which is involved in VEGF release by some normal and tumor cells. In the present work, we studied the effect of IL-1beta on VEGF release by rat mesangial cells, the transduction signal, and whether or not PGE2 is involved in this effect. IL-1beta induced a time-dependent formation of VEGF (analyzed by enzyme-linked immunosorbent assay) and PGE2 (analyzed by enzyme immunoassay). The latter correlated with microsomal-PGE-synthase (mPGES)-1 expression rather than with cyclooxygenase (COX)-2 in terms of protein, determined by Western blotting. No effect of IL-1beta on COX-1, cytosolic PGES, or mPGES-2 expression was observed. Indomethacin exerted a nonsignificant effect on IL-1beta-induced VEGF, and exogenously added PGE2 exhibited a nonsignificant stimulatory effect on VEGF formation. SB 203580, a p38 mitogen-activated protein kinase inhibitor, weakly inhibited the induction of VEGF by IL-1beta in a concentration-dependent manner, whereas LY 294002, a phosphoinoside 3-kinase (PI3-K) inhibitor, and rapamycin, a mammalian target of rapamycin (mTOR) inhibitor, strongly inhibited both IL-1beta- and tumor necrosis factor-alpha-induced VEGF formation in a concentration-dependent manner. Rapamycin also decreased glomerular VEGF levels in the anti-Thy1.1 model of experimental glomerulonephritis. In conclusion, the PI3-K-mTOR pathway seems to be essential in cytokine-induced release of VEGF in mesangial cells.

Effects of insulin-like growth factor I and II on prostaglandin synthesis and plasminogen activator activity in human umbilical vein endothelial cells

IGFs seem to contribute to the endothelial dysfunction observed in some vascular diseases. Because locally increased IGFs levels were detected in the preeclamptic fetoplacental unit, we hypothesized their involvement in the dysregulation of fibrinolysis and vascular tone typically observed in the fetoplacental compartment in this pregnancy disease. Therefore, in human umbilical vein endothelial cells (HUVECs), the potential effect of IGFs on the synthesis of plasminogen activators (PAs), PA inibitor-1 (PAI-1), and vasodilator and vasoconstrictor prostaglandins (PGs) was investigated. Moreover, in HUVECs treated with IGFs, the expression of cyclooxygenase (COX)-2, the rate-limiting enzyme in PG synthesis, was evaluated.HUVECs were treated for 24 h with IGFs (1-100 ng/ml) or IL-1beta (0.1 ng/ml). PA, PAI-1, and COX-2 mRNA was determined by RT-PCR and PG release and PA activity by RIA and colorimetric assay, respectively.We demonstrated an inhibition of urokinase-type PA activity and a 50% reduction of urokinase-type PA mRNA in HUVECs treated with IGFs. No effect was seen on PAI-1. Finally, both IGFs significantly decreased all PGs tested and COX-2 mRNA, whereas, as expected, IL-1beta had an opposite effect. In conclusion, our results suggest for IGFs a potential involvement in the endothelial dysfunction observed in preeclamptic fetoplacental unit.

An anti-inflammatory role for N-acetyl aspartate in stimulated human astroglial cells

Although N-acetyl-L-aspartate (NAA) has been shown to be important to myelin synthesis and osmotic regulation, the biological rationale for the high levels of NAA found in the brain remains unknown. Here, a human astroglial cell line (STTG) was treated with NAA and stimulated with ionomycin, ionomycin/PMA, or IL-1beta. PGE(2) levels in ionomycin-stimulated STTG cells decreased by 76% and > 95% at NAA concentrations of 10 and 20mM, respectively. NAA also decreased the levels of COX-2 protein and activated NF-kappaB in IL-1beta-stimulated STTG cells but had little effect on unstimulated cells. Also, NAA significantly decreased intracellular calcium levels in ionomycin/PMA-stimulated cells. NAA had no effect on total COX-2 activity or COX-2 mRNA. Acetylation of IkappaBalpha kinase, an acetylation target of aspirin, was not observed when NAA was present. These results demonstrate that NAA appears to be important in the modulation of inflammation in the human STTG astroglial cell line. The results of these findings are discussed in relation to neuronal pathologies that exhibit abnormal NAA levels within the brain.

Free radicals and lipid signaling in endothelial cells

Lipid mediators generated by oxidative pathways play essential roles in vascular homeostasis and disease through activating signal transduction pathways that control a variety of cellular functions, including vascular tone, gene expression, and leukocyte and platelet activation. Several enzyme families generate oxidized lipids, and a number of these are either constitutively expressed or inducible in the endothelium, including prostaglandin H synthases, lipoxygenases, and cytochrome P450 isoforms. Mediators generated by these enzymes are predominantly arachidonate-derived and include lipid hydroxides, epoxides, hydroperoxides, and prostanoids. These enzymes may also generate low levels of lipid-derived radicals in the vasculature following escape of substrate radicals from the active site. Lipid oxidation enzymes are often up-regulated in atherosclerosis and hypertension, with several lines of evidence suggesting that they play a central role in the pathogenesis of the disease process itself. This review will describe the isoforms of lipid oxidation enzymes present in endothelial cells focusing on their physiological functions and proposed roles in initiation and progression of vascular disease.

Estrogen stimulates arachidonoylethanolamide release from human endothelial cells and platelet activation

Estrogen replacement therapy has been associated with reduction of cardiovascular events in postmenopausal women, though the mechanism for this benefit remains unclear. Here we show that at physiological concentrations estrogen activates the anandamide membrane transporter of human endothelial cells and leads to rapid elevation of calcium (apparent within 5 minutes) and release of nitric oxide (within 15 minutes). These effects are mediated by estrogen binding to a surface receptor, which shows an apparent dissociation constant (K(d)) of 9.4 +/- 1.4 nM, a maximum binding (B(max)) of 356 +/- 12 fmol x mg protein(-1), and an apparent molecular mass of approximately 60 kDa. We also show that estrogen binding to surface receptors leads to stimulation of the anandamide-synthesizing enzyme phospholipase D and to inhibition of the anandamide-hydrolyzing enzyme fatty acid amide hydrolase, the latter effect mediated by 15-lipoxygenase activity. Because the endothelial transporter is shown to move anandamide across the cell membranes bidirectionally, taken together these data suggest that the physiological activity of estrogen is to stimulate the release, rather than the uptake, of anandamide from endothelial cells. Moreover, we show that anandamide released from estrogen-stimulated endothelial cells, unlike estrogen itself, inhibits the secretion of serotonin from adenosine diphosphate (ADP)-stimulated platelets. Therefore, it is suggested that the peripheral actions of anandamide could be part of the molecular events responsible for the beneficial effects of estrogen.

Hepoxilin B3 and its enzymatically formed derivative trioxilin B3 are incorporated into phospholipids in psoriatic lesions

In previous studies we observed that normal human epidermis forms 12-oxo-eicosatetraenoic acid (12-oxo-ETE) and hepoxilin B3 (HxB3) as major eicosanoids, both being elevated in psoriasis. We also observed that normal epidermis, in a reaction probably catalyzed by 12-lipoxygenase, only synthesize one of the two possible 10-hydroxy epimers of HxB3. We have now extended these previous studies investigating further transformation of HxB3 into trioxilin B3 (TrXB3) and esterification of both into phospholipids. Phospholipids were extracted from normal epidermis and from psoriatic scales. A combination of high performance liquid chromatography and gas chromatography-mass spectrometry analysis demonstrated the occurrence of HxB3 and TrXB3 in the phospholipids of psoriatic lesions. Alkaline- and phospholipase-A2-mediated hydrolysis of the phospholipids yielded similar quantities of both HxB3 and TrXB3 indicating their preference for the sn-2 position of glycerophospholipids. The thin layer chromatography analysis of the phospholipid classes after incubation of epidermal cells with [14C]-labeled HxB3, TrXB3, 12-hydroxy-eicosatetraenoic acid (12-HETE), 12-oxo-ETE, or 15-HETE showed that 12-HETE was the most esterified (12-HETE >15-HETE > TrXB3 > 12-oxo-ETE > HxB3). HxB3 and TrXB3 were mainly esterified in phosphatidyl-choline and phosphatidyl-ethanolamine. HxB3 was also enzymatically converted into TrXB3 in vitro. HxB3 epoxide hydrolase-like activity was not observed when boiled tissue was incubated with [14C]-HxB3, this activity being located in the cytosol fraction (100,000 x g supernatant) of fresh tissue. These findings suggest that in vivo some part of HxB3 is transformed into TrXB3 and both compounds are partially incorporated into the phospholipids.

Mesangial cells release untransformed prostaglandin H2 as a major prostanoid

BACKGROUND

Prostaglandin H2 (PGH2) is the precursor of the other prostanoids and exhibits a vasoconstricting activity. Glomerular mesangial cells are an important source of vasoactive prostanoids in kidney. Hence, the present investigation focused on the release of untransformed PGH2 by rat glomerular mesangial cells (RGMCs).

METHODS

Synthesis of prostanoid by resting and interleukin-1beta (IL-1beta)-treated (overnight) RGMCs from exogenous or endogenous arachidonic acid (AA) was assessed by high-performance liquid chromtography or enzyme immunoassay, respectively. Cyclo-oxygenase isoforms were determined by Western blotting. Release of untransformed PGH2 from exogenous AA was evaluated in RGMCs and intact glomeruli as the difference of PGF2alpha formed in the incubations performed in the presence and in the absence of SnCl2 or measuring the ability of aspirin-treated platelets to form thromboxane B2 (TXB2) in mixed incubations of platelets and RGMCs or glomeruli.

RESULTS

The prostanoids formed by RGMCs were PGE2, PGF2alpha, PGI2 and PGD2. SnCl2 totally deviated formation of PGE2 and PGD2 toward PGF2alpha in resting RGMCs, whereas PGE2 was only partially deviated toward PGF2alpha in IL-1beta-treated RGMCs. The PGE2/PGD2 ratio in resting RGMCs was similar to that expected for nonenzymatic isomerization of PGH2, whereas this ratio was higher in IL-1beta-treated RGMCs, suggesting the induction of PGE synthase by IL-1beta. Aspirin-treated platelets formed TXB2 when either RGMCs or intact glomeruli were present in the incubation and formation of TXB2 was approximately fourfold higher with IL-1beta-treated RGMCs or glomeruli.

CONCLUSIONS

RGMCs and intact glomeruli released substantial amounts of untransformed PGH2, which was enhanced following exposure to IL-1beta.

In vitro based index of topical anti-inflammatory activity to compare a series of NSAIDs

The aim of the present work was to generate an index to predict topical efficiency of a series of nonsteroidal anti-inflammatory drugs (NSAIDs): indomethacin, diclofenac, ketoprofen, piroxicam, tenoxicam and ketorolac. This index took into account both biopharmaceutic and pharmacodynamic aspects. The biopharmaceutic aspect, based on the maximal flux (J(m)), was determined experimentally from transdermal studies carried out with human skin in previous work. The pharmacodynamic aspect, based on the ability to inhibit cyclooxygenase-2 (COX-2) in vitro, was determined by incubating human dermal fibroblasts in culture, pre-treated with phobol-12-myristate-13-acetate (PMA) for 6 h, with 25 microM [(14)C]-arachidonic acid (AA) in the presence of several drug concentrations. The most potent inhibitor of COX-2 activity in induced fibroblasts was diclofenac while indomethacin, ketoprofen and ketorolac were approximately equipotent. Piroxicam and tenoxicam were inhibitors at higher concentrations. Based on the proposed index of the topical anti-inflammatory activity (ITAA) diclofenac, ketorolac, ketoprofen and indomethacin exhibited acceptable efficiency for external use. However, piroxicam and tenoxicam showed the lowest topical anti-inflammatory activity of the series assayed. In conclusion, indomethacin ketorolac, ketoprofen and diclofenac have shown good intrinsic feasibility for formulation into topical pharmaceutical forms. However, for dermatological formulations of oxicams, use of penetration enhancers may be unavoidable.

Human vascular smooth muscle cells but not endothelial cells express prostaglandin E synthase

In a previous work, we postulated that endothelial cells possess only the following 2 enzymes involved in prostanoid synthesis: cyclooxygenase and prostacyclin synthase. The present work focused on investigating the expression of prostaglandin (PG) E synthase (PGES) in vascular cells. After incubation of vascular smooth muscle cells (SMCs) and human umbilical vein endothelial cells (HUVECs) with [(14)C]arachidonic acid, the profile of prostanoid synthesis was assessed by HPLC. Untransformed PGH(2) released by the cells was evaluated as the difference in the formation of PGF(2alpha) in the incubations performed in the presence and in the absence of SnCl(2). Resting SMCs and SMCs stimulated with phorbol 12-myristate 13-acetate (PMA), lipopolysaccharide (LPS), interleukin (IL)-1beta, and tumor necrosis factor (TNF)-alpha formed PGE(2) and PGI(2) (evaluated as 6-oxo-PGF(1alpha)), and in the presence of SnCl(2) only a small amount of PGE(2) was deviated toward PGF(2alpha). In contrast, resting and stimulated HUVECs produced PGI(2), PGE(2), PGF(2alpha), and PGD(2), and SnCl(2) completely diverted PGE(2) and PGD(2) toward PGF(2alpha). Reverse transcriptase-polymerase chain reaction analysis shows that mRNA encoding for PGES was not present in HUVECs and in endothelial cells from saphenous vein. Nevertheless, PGES was expressed in SMCs and induced by IL-1beta and TNF-alpha, and by PMA and LPS, although to a lesser extent. Whereas SMC stimulation led to an increase in the synthesis of PGE(2) and PGI(2) but not of untransformed PGH(2), stimulation of endothelial cells resulted in an enhanced release of the vasoconstricting prostanoid PGH(2).

Transcellular formation of thromboxane A(2) in mixed incubations of endothelial cells and aspirin-treated platelets strongly depends on the prostaglandin I-synthase activity

Despite an almost total suppression of platelet cyclooxygenase (COX) by aspirin, as monitored ex vivo, incomplete suppression of thromboxane (Tx)A(2) metabolite excretion has been detected in some patients with unstable angina treated with low doses of aspirin. A plausible explanation for this finding is the transcellular formation of TxA(2) by platelets from prostaglandin H(2) released by endothelial cells. We recently reported that probably only COX and PGI-synthase (PGIS) are involved in the biosynthesis of prostanoids in endothelial cells. The present work was thus focused to ascertain the dependence of the transcellular biosynthesis of TxA(2), by endothelial cells and aspirin-treated platelets, on the relative activity of these enzymes. Synthesis of eicosanoids from exogenous and endogenous arachidonic acid (AA) by mixed incubations of human umbilical vein endothelial cells (HUVEC) in culture and aspirin-treated platelets were determined by HPLC and enzyme immune assay. The ratio of COX to PGIS activities was modified in HUVEC by treatment with interleukin-1beta (IL-1beta). Transcellular formation of TxA(2) was only relevant when HUVEC overexpressed COX-2 (monitored by RT-PCR and Western blotting), and in these conditions TxA(2) formation started 2 minutes after substrate addition. Progression curves showed that half-times (t(1/2)) of the COX and PGIS activity were 2.73 and 0.47 minutes, respectively, in resting HUVEC, whereas these values for IL-1beta-treated cells were 1.33 and 0.07 minutes, respectively, indicating that expression of COX-2 increased the rate of PGIS "suicide" inactivation. Collectively, these results indicated that not only enhanced COX activity but also substantial PGIS inactivation was required for significant transcellular biosynthesis of TxA(2).

The role of linoleic acid in endothelial cell gene expression. Relationship to atherosclerosis

There is evidence that linoleic acid plays a critical role in gene expression and vascular function as it relates to the pathogenesis of atherosclerosis. The lipid environment, particularly linoleic acid and its derivatives, of the vascular endothelium may profoundly influence the inflammatory response mediated by cytokines. Modulations in the level of activity of a select set of endothelial transcription factors appear to provide a mechanism for linking lipid/cytokine-mediated vessel wall dysfunction, including endothelial cell activation, altered proteoglycan metabolism, and endothelial barrier dysfunction, with the onset of atherosclerotic lesion formation. The activity of endothelial transcription factors is in part regulated by the balance of cellular oxidative stress and antioxidant status. Our data suggest that linoleic acid can activate the vascular endothelium and may thus be an atherogenic fatty acid. Furthermore, nutrients/chemicals with antioxidant properties can protect endothelial cells against lipid-mediated cell injury, suggesting that oxidative stress is a critical component in linoleic acid-mediated gene expression. Our discoveries that linoleic acid can influence significantly the cytokine-mediated inflammatory response may open new fields in dietary intervention of atherosclerosis.

High expression of human 15-lipoxygenase induces NF-kappaB-mediated expression of vascular cell adhesion molecule 1, intercellular adhesion molecule 1, and T-cell adhesion on human endothelial cells

Expression of 15-lipoxygenase (15-LO) is induced over 100-fold in early fatty streak lesions. 15-LO activity leads to the production of specific lipid hydroperoxides, which can have major effects on the expression of proinflammatory genes involved in atherogenesis. We have used retrovirus-mediated gene transfer to achieve stable high expression of 15-LO in human endothelial ECV304 cells. These cells were used to study the effects of 15-LO on the expression of vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1), activation of nuclear factor kappa B (NF-kappaB), and T-cell adhesion on endothelial cells. NF-kappaB activation was greatly potentiated by increased 15-LO activity in the stably transduced cells, and both VCAM-1 and ICAM-1 were significantly induced in these cells in response to tumor necrosis factor-alpha (TNF-alpha) and phorbol 12-myristate 13-acetate (PMA) stimulation, as studied by flow cytometry. The induction of ICAM-1 was sensitive to antioxidants in a dose-dependent manner. The adherence of Jurkat T cells on the 15-LO-expressing endothelial cells was markedly induced after PMA stimulation. These results indicate that 15-LO activity may be involved in the early pathogenesis of atherosclerosis by inducing VCAM-1 and ICAM-1 expression and by increasing T-cell adhesion on the endothelium.

Prevention of Experimental Allergic Encephalomyelitis via Inhibition of IL-12 Signaling and IL-12-Mediated Th1 Differentiation: An Effect of the Novel Anti-Inflammatory Drug Lisofylline

Experimental allergic encephalomyelitis (EAE) is an inflammatory, CD4+ Th1-mediated autoimmune disease, which serves as a model for multiple sclerosis. We examined the effect of a novel anti-inflammatory drug, lisofylline (LSF), on EAE induced either by injection of mouse spinal cord homogenate or following transfer of myelin basic protein-reactive T cells. Orally administered LSF significantly inhibited EAE in both cases, decreasing peak clinical scores by &gt;70% and &gt;80%, respectively. In addition, analysis of representative spinal cord sections from LSF-treated mice showed complete lack of demyelination and lymphocyte infiltration. The reduction in EAE correlated with the inhibition of Th1 differentiation by LSF in vivo, as indicated by a reduction in T cell IFN-γ production ex vivo after Ag restimulation. The inhibition of Th1 differentiation in vivo is consistent with a block in IL-12 receptor signaling, because LSF blocked IL-12-driven Th1 differentiation and T cell proliferation in vitro, yet had no effect on IL-12 secretion from APCs ex vivo or in vitro.

Leukotriene A4 hydrolase and leukotriene C4 synthase activities in human chondrocytes: transcellular biosynthesis of Leukotrienes during granulocyte-chondrocyte interaction

OBJECTIVE

To investigate the cooperation of chondrocytes and polymorphonuclear cells (PMN) in the biosynthesis of leukotrienes (LT).

METHODS

PMN, resting and interleukin-1beta-stimulated cultured human chondrocytes, and mixtures of both cell types were incubated with A23187 and/or 14C-arachidonic acid (14C-AA). To explore the presence of LTC4 synthase and LTA4 hydrolase, the chondrocytes were incubated with authentic LTA4. Eicosanoids were analyzed using high performance liquid chromatography techniques.

RESULTS

Chondrocytes formed only prostaglandin E2 and minor amounts of 15-HETE and 11-HETE, the production of all of which was inhibited by 1 microM indomethacin. Incubation of PMN and chondrocytes produced more LTC4 from endogenous and exogenous AA, and more LTB4 from endogenous AA, than incubation of PMN alone, which was consistent with the presence of LTC4 synthase and LTA4 hydrolase activities in chondrocytes. Chondrocytes also slightly increased the level of PMN production of all 5-lipoxygenase (5-LO)-derived products from endogenous AA.

CONCLUSION

Human chondrocytes form eicosanoids from AA only by the cyclooxygenase pathway. Chondrocytes cooperate in the transcellular biosynthesis of LT since they possess LTA4 hydrolase and LTC4 synthase activities and increase metabolism by the 5-LO pathway in PMN.

Rate of vasoconstrictor prostanoids released by endothelial cells depends on cyclooxygenase-2 expression and prostaglandin I synthase activity

This study was undertaken to investigate the enzymatic regulation of the biosynthesis of vasoconstrictor prostanoids by resting and interleukin (IL)-1(beta)stimulated human umbilical vein endothelial cells (HUVECs). Biosynthesis of eicosanoids in response to IL-1beta, exogenous labeled arachidonic acid (AA), or histamine, as well as their spontaneous release, was evaluated by means of HPLC and RIA. HUVECs exposed to IL-1beta produced prostaglandin (PG) I2 for no longer than 30 seconds after the substrate was added irrespective of the cyclooxygenase (COX) activity, whereas the time course of PGE2 and PGD2 formation was parallel to the COX activity. The ratio of PGE2 to PGD2 produced by HUVECs was similar to that obtained by purified COX-1 and COX-2. Production of PGF2alpha from exogenous AA was limited and similar in both resting and IL-1beta-treated cells. PGF2alpha was the main prostanoid released into the medium during exposure to IL-1beta, whereas when HUVECs treated with IL-1beta were stimulated with histamine or exogenous AA, PGE2 was released in a higher quantity than PGF2alpha. PGF2alpha released into the medium during treatment with IL-1beta and the biosynthesis of PGE2 and PGD2 in response to exogenous AA or histamine increased with COX-2 expression, whereas this did not occur in the case of PGI2. We observed that PGI synthase (PGIS) mRNA levels were not modified by the exposure to IL-1beta, but the enzyme was partially inactivated. When SnCl2 was added to the incubation medium, the transformation of exogenous AA-derived PGH2 into PGE2 and PGD2 was totally diverted toward PGF2alpha. Overall, these results support the conclusions that PGE2 and PGD2 (and also probably PGF2alpha) were nonenzymatically derived from PGH2 in HUVECs. The concept that a high ratio of PGH2 was released by the IL-1beta-treated HUVECs and isomerized outside the cell into PGE2 and PGD2 was supported by the biosynthesis of thromboxane B2 by COX-inactivated platelets, indicating the uptake by platelets of HUVEC-derived PGH2. The IL-1beta-induced increase in the release of PGH2 by HUVECs was suppressed by the COX-2-selective inhibitor SC-58125 and correlated with both COX-2 expression and PGIS inactivation. An approach to the mechanism of inactivation of PGIS by the exposure to IL-1beta was performed by using labeled endoperoxides as substrate. The involvement of HO. in the PGIS inactivation was supported by the fact that deferoxamine, pyrrolidinedithiocarbamate, DMSO, mannitol, and captopril antagonized the effect of IL-1beta on PGIS to different degrees. The NO synthase inhibitor NG-monomethyl-L-arginine also antagonized the PGIS inhibitory effect of IL-1beta, indicating that NO. was also involved. NO. reacts with O2-. to form peroxynitrite, which has been reported to inactivate PGIS. Homolytic fission of the O-O bond of peroxynitrite yields NO2. and HO.. The fact that 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy-PTIO), which reacts with NO. to form NO2., dramatically potentiated the IL-1beta effect suggests that NO2. could be a species implicated in the inactivation of PGIS. Cooperation of HO. was supported by the fact that DMSO partially antagonized the effect of carboxy-PTIO. Although our results on the exact mechanism of the inactivation of PGIS caused by IL-1beta were not conclusive, they strongly suggest that both NO. and HO. were involved.

Glutathione peroxidase mimics prevent TNFalpha- and neutrophil-induced endothelial alterations

Based on the assumption that glutathione peroxidase (GPx) activity might be limiting in preventing peroxide-induced impairment of endothelial regulatory functions, we studied the effect of a series of new selenium-containing GPx mimics on endothelial cells exposed to an inflammatory stress. The two compounds that have the highest GPx activity, BXT-51072 and BXT-51077, were shown to be the most efficient inhibitors of leukocyte recruitment by human umbilical vein endothelial cells (HUVEC), upon incubation with neutrophils (10-fold excess over HUVEC) and with 1 ng/ml TNF-alpha for 1 or 3.5 h. When HUVEC were pre- and cotreated with 10 microM of either compound, neutrophil adhesion and endothelial alteration were markedly inhibited, as assessed by immunoassays of myeloperoxidase and von Willebrand factor, respectively. These two GPx mimics were also found to be the most efficient inhibitors of the TNFalpha-induced endothelial expression of P- and E-selectin and of the TNFalpha- or interleukin1-induced endothelial release of interleukin-8. Our results demonstrate that GPx mimics such as BXT-51072 behave as potent antagonists of TNF-alpha and interleukin-1 through the downregulation of endothelial proinflammatory responses.

Occurrence of hepoxilins and trioxilins in psoriatic lesions

We recently found that normal human epidermis produces relatively high amounts of hepoxilins and trioxilins in vitro. Therefore, the aim of this study was to demonstrate the presence of these compounds in psoriatic lesions. Extracts from scales of patients with chronic stable plaque psoriasis were analyzed by a combination of high performance liquid chromatography and gas chromatography-mass spectrometry techniques. We found that the levels of hepoxilin B3 were more than 16-fold higher in psoriatic scales than in normal epidermis (3.2+/-2.3 and < 0.2 ng per mg, respectively), whereas hepoxilin A3 was not detected in any sample. Trioxilins were semiquantitated and referred to 12-hydroxyeicosatetraenoic acid, ratios of trioxilins A3 and B3 12-hydroxyeicosatetraenoic acid in psoriatic lesions were 0.65+/-0.23 and 0.32+/-0.28, respectively, and they were not detected in normal epidermis. The presence of a great amount of trioxilin A3 strongly suggests that hepoxilin A3 was present in psoriatic lesions and it was totally degraded to trioxilin A3 during the analysis procedure. Our results demonstrate that hepoxilins and trioxilins are produced by human skin in vivo and that the levels of these compounds are increased in psoriasis. The reported biologic activities of hepoxilins indicate that they could amplify and maintain the inflammatory response. Our results reinforce the idea that these compounds could play a role as mediators in the inflammatory response in skin, particularly in psoriasis.

Bioenergetics of rat prostate cancer cell migration

BACKGROUND

Increased cell motility and increased glycolysis are two well-known hallmarks of cancer. We undertook these studies to determine whether increased glycolysis is required for prostate cancer cell locomotion.

METHODS

We studied the highly metastatic MatLu cell line, which is a variant of the Dunning R-3327 rat prostate adenocarcinoma model. Using videomicroscopy and computer image analysis, we compared the speed of migration of cells grown in serum-free medium in either the presence or absence of glucose.

RESULTS

We found that cells grown in glucose-free, conditioned medium maintained speeds of migration and intracellular ATP levels for 24 hr which were equivalent to those of cells grown in conditioned medium containing glucose. In contrast, migration was significantly inhibited by growth in glucose-free, unconditioned medium. We also tested the effect of antimycin A and rotenone, two inhibitors of mitochondrial electron transport, on cell migration and ATP levels. Antimycin A had no significant effect on either feature, while rotenone slightly inhibited cell migration without affecting ATP levels.

CONCLUSIONS

1) Glycolysis is not necessary for rat prostate cancer cell locomotion in the presence of conditioned medium. 2) MatLu cells grown in the absence of both serum and conditioned medium require glucose to maintain cellular ATP levels and cell migration. 3) MatLu cells in conditioned medium adapt to inhibition of glycolysis or mitochondrial respiration by increasing the activity of the uninhibited pathway.

Interleukin-1-induced nuclear factor kappa B activation is inhibited by overexpression of phospholipid hydroperoxide glutathione peroxidase in a human endothelial cell line

Oxygen radicals are commonly accepted mediators in the tumour necrosis factor-mediated nuclear factor kappa B (NF kappa B) signalling cascade, but evidence for their role during interleukin-1 (IL-1) signalling is lacking. To test the involvement of hydroperoxides we investigated whether IL-1-induced NF kappa B activation could be influenced by glutathione peroxidases (GPx). These enzymes remove hydroperoxides with various specificities for the hydroperoxide substrate. By overexpressing phospholipid hydroperoxide glutathione peroxidase (PHGPx), which characteristically reacts with lipophilic hydroperoxides, the roles of H2O2 and lipid hydroperoxides were assessed. A human umbilical endothelial cell line, ECV 304, was stably transfected with the genes for both PHGPx and selenophosphate synthetase (selD), which provides selenophosphate for selenoprotein biosynthesis. When grown in selenium-deficient culture medium, the double-transfected clone (ECVPHGPx+SelD+) expressed 5-fold higher (P<0.005) PHGPx activity (measured by phosphatidylcholine hydroperoxide removal) than controls. The rate of H2O2 removal was also significantly (P<0.01) higher in this clone. When grown with high levels of extracellular selenium (up to 100 nM selenite), PHGPx activity and H2O2 removal were enhanced substantially in control cells and transfected cells. Under these conditions, PHGPx activity was 1.7-fold (P<0.005) higher in ECVPHGPx+SelD+, but H2O2 removal was the same as in controls. IL-1-induced NF kappa B activation was inhibited by selenium supplementation in control cells. In ECVPHGPx+SelD+ under conditions of selenium restriction, IL-1 induced NF kappa B activation only to a similar extent as under conditions of selenium supplementation in controls, and activation was abolished with 50 nM sodium selenite. These results show that overexpressed PHGPx is sufficient to inhibit NF kappa B activation, and suggests that NF kappa B activation by IL-1 is mediated by a preferential substrate of PHGPx, such as a fatty acid hydroperoxide, rather than by H2O2, the preferred substrate of the more abundant cytosolic GPx.

Modulating phosphatidic acid metabolism decreases oxidative injury in rat lungs

We determined that lisofylline, a potent inhibitor of oleate- and linoleate-containing phosphatidic acid formation (half-maximal inhibitory concentration = 40 nM), prevented oxidant-mediated capillary leak in isolated rat lungs given interleukin-8 (IL-8) intratracheally and perfused with human neutrophils. Lung leak was prevented by lung, but not neutrophil, lisofylline pretreatment. Furthermore, although lisofylline inhibited IL-8-stimulated neutrophil production of phosphatidic acid in vitro, it did not prevent IL-8-stimulated neutrophil adherence, chemotaxis, or intracellular calcium mobilization or N-formyl-Met-Leu-Phe (fMLP)-stimulated oxidant production in vitro. Lisofylline also prevented acute capillary leak in isolated rat lungs perfused only with the oxidant generator purine-xanthine oxidase but did not scavenge O2-(+) or H2O2 in vitro. Finally, lisofylline-mediated protection against lung leak in both models was associated with alterations in lung membrane free fatty acid acyl composition (as reflected by the decreased ratio [linoleate + oleate]/[palmitate]). We conclude that lisofylline prevented both neutrophil-dependent and neutrophil-independent oxidant-induced capillary leak in isolated rat lungs and that protection appears to be mediated by blocking intrinsic lung linoleoyl phosphatidic acid metabolism. We speculate that lisofylline, in addition to our previously reported effects on cytokine signaling by intrapulmonary mononuclear cells, alters intrinsic pulmonary capillary membrane composition and renders this barrier less vulnerable to oxidative damage.

Selective induction of cyclo-oxygenase-2 activity in the permanent human endothelial cell line HUV-EC-C: biochemical and pharmacological characterization

1. Cyclo-oxygenase (COX), the enzyme responsible for the conversion of arachidonic acid (AA) to prostaglandin H2 (PGH2), exists in two forms, termed COX-1 and COX-2 which are encoded by different genes. COX-1 is expressed constitutively and is known to be the site of action of aspirin and other nonsteroidal anti-inflammatory drugs. COX-2 may be induced by a series of pro-inflammatory stimuli and its role in the development of inflammation has been claimed. 2. Endothelial cells are an important physiological source of prostanoids and the selective induction of COX-2 activity has been described for finite cultures of endothelial cells, but not for permanent endothelial cell lines. 3. The HUV-EC-C line is a permanent endothelial cell line of human origin. We have determined the COX activity of these cells under basal conditions and after its exposure to two different stimuli, phorbol 12-myristate 13-acetate (PMA) and interleukin-1 beta (IL-1 beta). 4. Both PMA and IL-1 beta produced dose- and time-dependent increases of the synthesis of the COX-derived eicosanoids. These increases were maximal after the treatment with 10 nM PMA for 6 to 9 h. Under these conditions, the main eicosanoid produced by the cells was PGE2. 5. The increase of COX activity by PMA or IL-1 beta correlated with an increase of the enzyme's apparent Vmax, whilst the affinity for the substrate, measured as apparent Km, remained unaffected. 6. Treatment of the cells with PMA induced a time-dependent increase in the expression of both COX-1 and COX-2 mRNAs. Nevertheless, this increase was reflected only as an increase of the COX-2 isoenzyme at the protein level. 7. The enzymatic activity of the PMA-induced COX was measured in the presence of a panel of enzyme inhibitors, and the IC50 values obtained were compared with those obtained for the inhibition of human platelet COX activity, a COX-1 selective assay. Classical non-steroidal anti-inflammatory drugs (NSAIDs) inhibited both enzymes with varying potencies but only the three compounds previously shown to be selective COX-2 inhibitors (SC-58125, NS-398 and nimesulide) showed higher potency towards the COX of PMA-treated HUV-EC-C. 8. Overall, it appears that the stimulation of the HUV-EC-C line with PMA selectively induces the COX-2 isoenzyme. This appears to be a suitable model for the study of the physiology and pharmacology of this important isoenzyme, with a permanent endothelial cell line of human origin.

Prostaglandin H-synthase-2 is the main enzyme involved in the biosynthesis of octadecanoids from linoleic acid in human dermal fibroblasts stimulated with interleukin-1beta

This study was focused on the characterization of the metabolism of linoleic acid by human dermal fibroblasts and the effect of interleukin-1 on the biosynthesis of octadecanoids. Dermal fibroblasts untreated and treated with recombinant IL-1beta were incubated with exogenous labeled linoleic acid. A combination of high performance liquid chromatography and gas chromatography-mass spectrometry was used as the analytic technique. We found that dermal fibroblasts convert linoleic acid mainly into 13-hydroxy-9-cis,11-trans-octadecadienoic acid (13-HODE) and 9-hydroxy-10-trans,12-cis-octadecadienoic acid (9-HODE), 13(S)-HODE and 9(R)-HODE being the predominant enantiomers. IL-1beta increased the formation of both 13-HODE and 9-HODE in a concentration-dependent manner with similar EC50 values as for prostanoid formation. This effect of IL-1beta on HODEs formation was concomitant with the expression of prostaglandin H-synthase-2. Formation of octadecanoids was inhibited in a concentration-dependent manner by acetylsalicylic acid and indomethacin. Dexamethasone, actinomycin D, and cycloheximide abolished the effect of IL-1beta on HODEs biosynthesis. Octadecanoid biosynthetic activity was associated with the microsomal fraction. Dermal fibroblasts incorporated [14C]-9-HODE and [14C]-13-HODE into phospholipids, mainly into phosphatidylcholine. IL-1beta increased significantly the esterification of 13-HODE in all glycerophospholipids, the major increase being observed in phosphatidylinositol. These results indicate that prostaglandin H-synthase-2 is the enzyme responsible for the increase in the ability to form HODEs of dermal fibroblasts stimulated with IL-1beta.

An increase in serum C18 unsaturated free fatty acids as a predictor of the development of acute respiratory distress syndrome

OBJECTIVE

No means exist for predicting the acute respiratory distress syndrome (ARDS), which complicates sepsis, trauma, and a variety of clinical disorders. Because activation of phospholipid-signaling pathways involving the acyl chains oleate and linoleate may initiate and amplify the inflammatory response, and thereby lead to the development of ARDS, we examined whether serum concentrations of these bioactive lipids increase and are predictive of ARDS in at-risk patients.

DESIGN

Part I: A prospective, single-blind trial. Part II: A prospective, randomized, double-blind trial.

SETTING

General intensive therapy units in five university teaching hospitals.

SUBJECTS

Part I: Thirty-nine healthy control patients were studied to determine normal distribution of serum acyl values, followed by 30 patients admitted with onset of sepsis, trauma, or development of ARDS (within 24 hrs of admission) over a 1-yr period. Part II: Eight patients admitted with sepsis syndrome over a 2-month period.

INTERVENTIONS

Part II: Patients were randomized to receive the substituted methylxanthine, lisofylline (CT1501R), or an identically presented placebo.

MEASUREMENTS AND MAIN RESULTS

We measured the serum free fatty acid concentrations in the 39 healthy control subjects, and then we prospectively examined the serum free fatty acid concentrations in 30 age-matched patients in samples obtained within 24 hrs from the onset of sepsis, trauma, or development of ARDS. We then prospectively studied eight septic, at-risk patients who were matched for age, Acute Physiology and Chronic Health Evaluation II scores, Multiple Organ Failure index, and Glasgow Coma Score, in a double-blind, placebo-controlled, pilot study. These patients included four patients who received no treatment and four patients who received lisofylline, a compound that decreases serum unsaturated free fatty acids and diminishes acute lung injury in animals caused by sepsis and/or trauma. The calculated ratios of serum free fatty acids (Le., the ratio of C18 unsaturated fatty acids linoleate and oleate to fully saturated palmitate, C16:0) increased and predicted the development of ARDS in at-risk patients. Serum samples from the 30 patients, obtained within 24 hrs from the onset of sepsis, trauma, or development of ARDS, had significantly increased mean acyl chain ratios (1.42 +/- 0.35 [SD]) compared with healthy control subjects (0.86 +/- 0.25; p < .01). Sera from 13 patients with sepsis or trauma who did not develop ARDS (group A [at-risk, non-pre-ARDS]) also had increased acyl ratios (1.23 +/- 0.27) compared with sera from healthy control subjects (0.86 +/- 0.25; p < .01). Sera from seven patients who subsequently developed ARDS (group B [at-risk, pre-ARDS]) had higher acyl ratios (1.70 +/- 0.21) than group A at-risk patients who did not develop ARDS (1.23 +/- 0.27; p < .01) or healthy control subjects (0.86 +/- 0.25; p < .001). Sera from ten group C patients with ARDS at the time of admission to the study had the highest acyl ratios (1.80 +/- 0.75), which exceeded values for healthy control subjects (p < .001) and group A at-risk patients without ARDS (p = .01), but were not significantly different then group B at-risk, pre-ARDS patients (p = .17). Prospective study of eight septic, at-risk patients demonstrated significantly (p < .05) increased serum acyl ratios in the four untreated patients (findings consistent with the first study) but a significantly (p = .02) reduced ratio in the four at-risk patients treated with lisofyline.

CONCLUSIONS

Increases in unsaturated serum acyl chain ratios differentiate between healthy and seriously iII patients, and identify those patients likely to develop ARDS. Thus, the serum acyl ratio may not only prospectively identify and facilitate the assessment of new treatments in patients at highest risk for developing ARDS, but may also lead to new insights about the pathogenesis of ARDS.