6-keto PGF1 Research Articles

Lipid Mediator Production in Acute and Chronic Pancreatitis in the Rat

Pancreatic production of lipid mediators of inflammation, including eicosanoids and platelet-activating factor (PAF), was examined in two models of pancreatitis in the rat. Chronic pancreatitis was induced by ligation of the pancreatic duct and acute pancreatitis by infusion of sodium taurocholate into the pancreatic duct. In the model of chronic pancreatitis, prostaglandin E 2 (PGE 2), PGD 2, 6-keto PGF 1α, thromboxane B 2 (TXB 2), and PAF increased significantly in the pancreas in a similar fashion, whereas leukotriene B 4 (LTB 4) remained unchanged. BN52021, a PAF antagonist, reduced the accumulation of pancreatic TXB 2, 6-keto PGF 1α, and PGD 2, and did not affect PGE 2. In the model of acute pancreatitis, LTB 4 increased, whereas PGE 2, TXB 2, and 6-keto PGF 1α decreased significantly; PGD 2 changed slightly; and PAF was undetectable. The present results indicate that mild chronic pancreatitis is accompanied by the production and accumulation of a wide spectrum of lipid mediators while LTB 4 was the only lipid mediator detected at biologically active concentrations in the model of severe acute pancreatitis. It is suggested that various mediators are involved in establishing a balance between inflammation and the repair of the inflamed pancreatic tissue observed in mild chronic pancreatitis. While both eicosanoids and PAF are involved in such self-limiting responses to inflammatory challenge, PAF seems to play a central role in instigating the production of the various other mediators detected in the model of chronic pancreatitis. In the model of acute pancreatitis while the deficiency of various lipid mediators may render the pancreatic tissue more susceptible to acute damage, enhanced LTB 4 appears to contribute to the destructive pathology observed. In conclusion, the diversity of the pancreatic inflammatory responses associated with changes in the production of lipid mediators (hypersecretion or hyposecretion) suggests not only the pathophysiological importance of the individual mediators but also rational strategies for therapeutic intervention.

Sodium loading and renal prostaglandins in old rats

1. 1. Previous studies have shown that altered synthesis of prostaglandins (PGs) in the kidney of ageing rats contributes to impaired Na conservation during sodium deprivation. In the present study, we wished to assess whether the disturbance of prostaglandin synthesis also affects the response to sodium loading in old rats. 2. 2. We measured the urinary excretion of thromboxane B 2 (TXB 2), 6-keto PGF 1α (6KPGF 1α) and PGE 2 in young (3–4 months) and old (20–21 months) rats after 24, 48 and 72 h of Na loading. In a separate protocol, we measured prostanoid synthesis by isolated glomeruli, cortical homogenates, medullary and papillary slices from young and old rats in basal conditions and after 15 days of dietary Na loading. 3. 3. Young and old rats excreted similarly the Na load. The urinary excretion (U) of TXB 2 and 6KPGF 1α were unchanged during Na load in young rats. U6KPGF 1α, which was significantly higher in old rats and UTXB 2 which also tended to be elevated, decreased in old rats with Na loading. Sodium loading was associated with a transient increase of UPGE 2 in young, but not in old rats. 4. 4. TXB 2 synthesis was increased in all portions of the kidneys of old rats. 6KPGF 1α production was elevated in glomeruli and cortex and that of PGE 2 in cortex. In medulla and papilla only TXB 2 synthesis was enhanced. 5. 5. Sodium loading did not significantly change prostanoid synthesis in the kidneys of young rats. In old rats, glomerular and cortical TXB 2 decreased whereas medullary and papillary 6KPGF 1α increased. PGE 2 synthesis remained unaltered. 6. 6. The response to sodium loading in the kidneys of old rats could contribute to renal vasodilation and lead to increased natriuresis, explaining how old rats are able to excrete sodium normally despite reduced renal function.

Effects of cilostazol, a phosphodiesterase inhibitor, on urinary excretion of albumin and prostaglandins in non-insulin-dependent diabetic patients

Microalbuminuria is characteristic in diabetic nephropathy and is thought to be influenced by renal hemodynamics, especially by the metabolism of prostaglandins (PGs) in glomruli. To reduce urinary albumin excretion in patients with non-insulin-dependent diabetes mellitus (MIDDM), we administered 100 mg of cilostazol, a phosphodiesterase inhibitor, daily for 3 months. The urinary albumin index (UAI: μg albumin/mg creatinine) decreased significantly after 3 months of administering cilostazol. Urinary excrtions of thromboxane B 2 (TXB 2), a stable metabolite of thromboxane A 2, decreased significantly after treatment. However, it had no effects on urinary excretions of PGE 2 and 6-keto PGF 1α (6KF), a stable metabolite of prostacyclin. The ratio 6KF TXB 2 has been known to reflect the renal metabolism of PGs. In this study, urinary 6KF TXB 2 ratio increased significantly in parallel with a significant reduction of UAI. Cilostazol had no adverse effects on the control of blood glucose and lipids. In conclusion, cilostazol has a beneficial effect on AUI in patients with NIDDM by reducing renal production of TXB 2, which increases 6KF TXB 2 ratio.

The effects of dietary n-3 polyunsaturated fatty acids and cyclic AMP-elevating agents on tumor necrosis factor production by murine-resident and thioglycollate-elicited peritoneal macrophages

Tumor-necrosis factor (TNF), prostaglandin (PG) E 2, and 6-keto PGF 1a production by peritoneal macrophages was monitored following incubation with various cAMP-elevating agents and stimulation with lipopolysaccharide (LPS). Resident and thioglycollate (TG)-elicited macrophages were obtained from mice maintained for 4 weeks on diets containing 3 wt % n-6 fatty acids; 1.0 wt % n-3 polyunsaturated fatty acids (PUFA) + 1.5 wt % n-6 fatty acids; or 1.5 wt % n-3 PUFA + 1.5 wt % n-6 fatty acids. Increasing the n-3 PUFA content of the diet increased TNF production and decreased PG production by the resident peritoneal macrophages. The cAMP analog, 8-br cAMP, and the phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine, decreased TNF production by resident peritoneal macrophages from mice consuming all diets. The adenylate cyclase (AC) activators, cholera toxin and forskolin, only decreased TNF production by resident macrophages from mice consuming the higher level of n-3 PUFA. The effects of dietary n-3 PUFA on TNF production by the resident peritoneal macrophages appear not to be mediated by cAMP, as the cAMP-elevating agents did not eliminate the dietary effects on TNF production. TG-elicited macrophages produced more TNF and less PG than the resident peritoneal macrophages. Adding n-3 PUFA to the diet did not affect TNF nor PG production by TG-elicited macrophages. The cAMP-elevating agents decreased TNF production by TG-elicited macrophages from mice consuming diets with or without n-3 PUFA. These findings show that cAMP-elevating agents decrease TNF production by both resident and elicited peritoneal macrophages, but may not be involved in the effect of n-3 PUFA on TNF production by the resident peritoneal macrophages.

Correlation between umbilical artery resistance index, 6 ketoprostaglandin F1 α and thromboxane B 2 in the fetoplacental compartment in patients with pregnancy induced hypertension

Umbilical artery flow velocity waveforms (UAFVW's) were measured by Doppler ultrasound in 35 pregnant women with pregnancy induced hypertension. The stable hydration products of the vasoconstrictor and proaggregatory thromboxane A 2 and vasodilatory and anti-aggregatory prostacyclin (i.e. thromboxane B 2 (TxB 2) and 6 ketoprostaglandin F 1 α (6 keto PGF 1 α ) respectively) were measured in blood obtained from the umbilical vein and were assayed by radioimmunoassay. Abnormal umbilical artery Resistance Index (UARI) was associated with higher thromboxane B 2 levels, lower 6-ketoprostaglandin F 1 α levels and lower 6-keto PGF 1α TxB 2 ratio. Moreover, the umbilical artery Resistance Index was significantly correlated with the 6-keto PGF 1α thromboxane B 2 ratio suggesting an association between abnormal umbilical artery blood flow and altered prostacyclin/thromboxane balance in the fetoplacental compartment in patients with pregnancy induced hypertension (PIH).

Effects of starvation on the urinary contents of primary thromboxane and prostacyclin metabolites and a possible selenium-dependent role of prostacyclin in the renal handling of ketone bodies

The aim of this study was to investigate whether urinary prostanoids, as an index of renal synthesis of these compounds, are affected in selenium (Se) deficiency and, if so, whether such changes could add to our understanding of the high excretion of ketone bodies in Se-deficient rats (p < 0.005 vs Se-adequate rats). Male rats were fed a Se-deficient diet with less than 0.01 mg Se/kg or the same diet supplemented with 0.2 mg Se/kg. The urinary contents of prostaglandin E 2 (PGE 2), PGF 2α and 6-keto PGF 1α were not significantly affected by the Se status. However, there was a positive correlation between the urinary contents of ketone bodies and 6-keto PGF 1α in Se deficiency (with p < 0.02 for acetaoacetate and p < 0.05 for 3-hydroxybutyrate). In contrast, only negative (nonsignificant) relationships were observed between these same parameters in Se-adequate rats. No correlations between urinary contents of ketone bodies and PGE 2, PGF 2α or thromboxane B 2 (TXB 2) were obtained. Compared to fed rats, starvation caused a 4-fold increase in the urinary TXB 2 content in Se-adequate, as well as in Se-deficient rats (p < 0.001). Starvation had an opposite effect on the content of 6-keto PGF 1α, which decreased (to 64% that of fed animals p < 0.001) in Se-adequate rats and, nonsignificantly (to 93% that of fed animals) in the Se-deficient group. It is concluded that starvation profoundly affects the urinary contents (and thus, probably renal synthesis) of TX and prostacycline (PGI 2). The lack of significant decrease in the urinary level of 6-keto PGF 1α during starvation and the positive correlation between the urinary contents of ketone bodies and 6-keto PGF 1α in the Se-deficient rat indicate that renal PGI 2 plays a role in the increased ketonuria of these rats.

Cyclooxygenase and lipoxygenase metabolism in sodium taurocholate induced acute hemorrhagic pancreatitis in rats

Several studies have reported that prostanoids are involved in many of the physiopathological mechanisms underlying acute pancreatitis but their precise role in this disease remains to be established. The objective of this work is to evaluate the variation of local tissue production of prostanoids and lipoxygenase metabolites of arachidonic acid in acute pancreas inflammation induced by intraductal administration of 3.5 % sodium taurocholate (0.1 ml/100 mg body weight) in rats. Pancreatic tissue levels of leukotriene B 4 (LTB 4), 15 hydroxyeicosatetraenoic acid (15-HETE), 6-keto prostaglandin F 1α (6-keto PGF 1α), thromboxane B 2 (TXB 2) and prostaglandin E 2 (PGE 2) were determined by HPLC-RIA techniques at 5 and 60 minutes after induction of acute pancreatitis (AP). Prostanoids increased significantly at 5 minutes and LTB 4 and 15-HETE at 60 minutes. These data confirm that the prostanoid imbalance could be considered as an early specific response of the pancreas to the inflammatory events characteristic of induced AP while the altered levels of the lipoxygenase products (LTB 4 and 15-HETE) would be more of a nonspecific organ response associated to the high cellular infiltration rate and necrosis observed in the late phases of acute pancreatitis.

Protective effect of diclofenac sodium against endotoxic shock in anaesthetized pigs

The effect of diclofenac sodium was investigated on haemodynamics, haematologic and blood glucose values as well as the release of eicosanoids, tumor necrosis factor (TNF) and platelet activating factor (PAF) in anaesthetized pigs receiving 5 μg. kg −1 Escherichia coli lipopolysaccharide (LPS) over 60 min into the superior mesenteric artery. The animals were observed for an additional period of 2 h after the termination of LPS infusion. 15 of the 31 animals infused with LPS and not treated with diclofenac sodium died within 30 min after the commencement of LPS infusion (non-survivors), while the other 16 survived the experimental period of 3-h, though in a shock state (survivors). No alterations were observed in plasma concentrations of PAF or eicosanoids (TXB 2, 6-keto PGF 1α and LTB 4), but a marked increase was detected in TNF release in the nonsurvivors. A significant, though transient, increase in concentrations of PAF, TNF and eicosanoids studied characterized the survivors. Another group of 7 LPS-infused pigs was treated with diclofenac sodium (2 mg, kg −1, i.v. bolus 60 min before the start of LPS infusion, followed by a continuous infusion of 1 mg kg −1 h −1) 1 mg/kg −1/h −1. This treatment prevented death and shock despite the high concentrations of TNF and PAF. Concentrations of both cyclooxygenase and 5-lipoxygenase enzymes products were reduced. These data indicated that the beneficial effect of diclofenac sodium in LPS induced shock may be related to the reduced production of eicosanoids.

Comparison of Prostanoids and Their Precursor Fatty Acids in Human Hepatocellular Carcinoma and Noncancerous Reference Tissues

Eicosanoid production and the compositions of precursor fatty acids were determined in human cancerous and reference liver tissues. Seventeen hepatectomized cases (12 cases of hepatocellular carcinoma (HCC) and 5 cases of metastatic liver cancer) were evaluated. The cancerous tissues and the noncancerous reference tissues were separated, lipids were extracted, and the fatty acids were determined as methyl esters by gas chromatography. Prostanoids (6-keto PGF 1α and TXB 2) were measured by radioimmunoassay. In HCC, the levels of α-linolenic acid (ω-3) (0.41 ± 0.38 × 100 μg/g) and dochosahexaenoic acid (10.41 ± 4.96 × 100 μg/g) in liver cancer tissue were significantly less than those in the reference tissues. In HCC, the levels of TXB 2 reference (1.86 ± 2.77 pg/mg wet weight) and 6-keto PGF 1α were 10-fold higher than those in reference tissues. We speculate that in HCC higher prostanoid levels in the liver are related in part to tumor metabolism.

The phenytoin metabolite p-HPPH upregulates prostaglandin biosynthesis in human gingival fibroblasts challenged to interleukin-1

The effects of and interactions between the major phenytoin (PHT) metabolite 5-parahydroxyphenyl-5-phenylhydantoin (p-HPPH) and interleukin-1 (IL-1α, IL-1β) or tumor necrosis factor α (TNFα) on prostaglandin biosynthesis in human gingival fibroblasts were studied. IL-1α, IL-1β and TNFα, dose dependently, stimulated PGE 2 formation in gingival fibroblasts. The metabolite, p-HPPH (1.2–2.4 μg/ml), did not induce PGE 2 formation itself but potentiated IL-1α and IL1β induced PGE 2 formation in the gingival fibroblasts in a manner dependent on the concentration of both IL-1 and p-HPPH. The metabolite also stimulated IL-1 induced formation of 6-Keto PGF 1α, the stable breakdown product of PGI 2, in a dose dependent manner. IL-1β induces release of [ 3H]-arachidonic acid ([ 3H]-AA) from prelabelled fibroblasts, which was potentiated by p-HPPH (≥1.2 μg/ml). TNFα (≥1 ng/ml) significantly stimulated the biosynthesis of PGE 2 by a process that was also potentiated by p-HPPH. Addition of exogenous, unlabelled AA (10μM) caused an increase of PGE 2 formation in the fibroblasts that was not potentiated by p-HPPH (1.6 μg/ml). The results indicate that treatment with p-HPPH results in upregulation of prostaglandin synthesis in gingival fibroblasts challenged to IL-1 or TNFα at the level of phospholipase A 2.

Prostaglandin E production by uteri of ovariectomized pregnant rats receiving antiprogesterone steroid or in which progesterone has been withdrawn

Antiprogesterone steroid, ZK98299 (Schering, Germany) or RU38486 (Roussel Uclaf, France), has been administered to ovariectomized early pregnant rats receiving continuous steroid replacement. At 24 h later, uterine explants of rats treated with ZK98299 produced significantly greater amounts of prostaglandin E (PGE) than did controls or animals treated with RU38486. The PGE/PGF 2α production ratio for uteri of rats treated with ZK98299 or RU38486 was markedly lowered compared to controls, and a significant decrease occurred in the PGE 6 -keto PGF 1α production ratio for rats treated with RU38486. For ovariectomized early pregnant rats in which progesterone has been withdrawn, a significant reduction in uterine PGE production occurred when compared to control animals. There was also a marked decrease in PGE/PGF 2α production ratio, and the PGE 6 -keto PGF 1α production ratio tended to be lowered relative to controls. The stimulated production (as by ZK98299) or unchanged production of PGE (as by RU38486) indicates a selective action on uterine PGE synthesis among the antiprogesterone steroids, and these findings cannot be explained simply in terms of a blockage of progesterone receptors.

Pancreas prostanoid production in ischemia and reperfusion

This study was carried out to investigate the proprtion of the 6-keto prostaglandin F 1α (6-keto PGF 1α) and thromboxane B 2 (TXB 2) alteration that is due to ischemia in pancreas transplantation against the proportion due to reperfusion. For this purpose, Lewis rats were divided in three experimental groups: Group I=Control, Group II=Donor pancreas subjected to 15 minutes of cold ischemia, Group III=Same as group II but pancreas were transplanted to the recipient individual and then subjected to reperfusion. The results indicate that increases in pancreas 6-keto PGF 1α occur as a consequence of cold ischemia while TXB 2 remains unchanged. When blood flow was restored, 6-keto PGF 1α remained unchanged compared to the cold ischemic group while pancreatic levels of TXB 2 were significantly increased. These results suggest a different induction of prostanoid metabolism during ischemia and reperfusion in pancreatic tissue.

Acute hypoxia alters eicosanoid production of perfused pulmonary artery endothelial cells in culture

Hypoxia alters vascular tone which regulates regional blood flow in the pulmonary circulation. Endothelial derived eicosanoids alter vascular tone and blood flow and have been implicated as modulators of hypoxic pulmonary vasoconstriction. Eicosanoid production was measured in cultured bovine pulmonary endothelial cells during constant flow and pressure perfusion at two oxygen tensions (hypoxia: 4% O 2, 5% CO 2, 91% N 2; normoxia: 21% O 2, 5% CO 2, 74% N 2). Endothelial cells were grown to confluence on microcarrier beads. Cell cartridges ( N=8) containing 2 ml of microcarrier beads (≅ 5 × 10 6 cells) were constantly perfused (3 ml/min) with Krebs' solutions (pH 7.4, T 37°C) equilibrated with each gas mixture. After a ten minute equilibration period, lipids were extracted (C 18 Sep Pak®) from twenty minute aliquots of perfusate over three hours (nine aliquots per cartridge). Eicosanoids (6-keto PGF 1 α ; TXB 2; and total leukotriene [LT - LTC 4, LTD 4, LTE 4, LTF 4]) were assayed by radioimmunoassay. Eicosanoid production did not vary over time. 6-keto PGF 1 α production was increased during hypoxia (normoxia 291 ± 27 vs hypoxia 395 ± 35 ng/min/gm protein; p < 0.01). Thromboxane production (normoxia 19 ± 2 vs hypoxia 20 ± 2 ng/min/gm protein) and total leukotriene production (normoxia 363 ± 35 vs hypoxia 329 ± 29 ng/min/gm protein) did not change with hypoxia. These data demonstrated that oxygen increased endothelial prostacyclin production but did not effect thromboxane or leukotriene production.

Pathophysiology of Experimental Bovine Endotoxicosis: Endotoxin Induced Synthesis of Prostaglandins and Thromboxane and the Modulatory Effect of Some Non-Steroidal Anti-Inflammatory Drugs

Endotoxin-induced synthesis of thromboxane A2 (TXA2), prostacyclin (PGI2) and prostaglandin E2 (PGE2) was studied in 3 cows after intravenous E. coli endotoxin (055:B5-0.025 mg/kg b.w.) administration. Blood sampling and monitoring of clinical signs were performed from 2 h prior to until 6 h after endotoxin challenge. Blood samples were analyzed for stable hydrolysis products of TXA2 (TXB2), PGI2 (6-keto PGF) and PGE2 (bicyclic PGE2), biochemical and haematological parameters. In a similar experimental design the efficacy of the non-steroidal anti-inflammatory drugs (NSAID) flunixin meglumine (FM) and phenylbutazone (PB) in suppressing eicosanoid synthesis and clinical signs in response to endotoxin challenge was investigated. Two groups of cows, each comprising 2 animals, were treated with FM and PB prior to endotoxin challenge. It was observed that plasma concentrations of TXB2, 6-keto PGF and bicyclic PGE2 increased rapidly after endotoxin challenge. Concentrations were significantly elevated for hours and were correlated to the severity of clinical signs of endotoxicosis. Pretreatment with NSAID suppressed mediator production and alleviated clinical signs. The experiments suggest a certain pathophysiological role of TXA2, PGI2 and PGE2 for the early systemic ill-effects of bovine endotoxicosis.

Prostacyclin and thromboxane in pregnancy

Normal pregnancy is characterized by a reduction of the peripheral vascular resistance, an increased plasmavolume and an increased cardiac output. Hypertension during pregnancy and pre-eclampsia occurs mostly in nulliparae after the 20th week of pregnancy. In this complication of pregnancy an incomplete vascular adaptation of pregnancy is present. The disorder is responsible for an increased maternal and perinatal morbidity and mortality. Since a few years information is available on the role of prostacyclin (prostaglandin It, PGI,) and thromboxane (TXA,) in the cardiovascular changes of pregnancy and in the pathogenesis of preeclampsia. PGI, and TXA, are both metabolites of arachidonic acid (AA). AA is mainly stored in esterform in phospholipids of the cellmembrane and is released by phospholipase A2 and phospholipase C. Free AA is metabolized by the enzyme prostaglandin-H-synthase to the cyclic endoperoxides prostaglandin Gz (PGG2) and prostaglandin H, (PGH2). In the platelets, under influence of thromboxaneA,-synthase, PGH2 is preferentially converted to TXA,, which is spontaneously hydrolised to the inactive TXB2. TXA, is a strong inductor of platelet aggregation and is also a vasoconstrictor. In the endothelial cells of the vascular wall PGHz in preferentially converted to PGI, by the enzyme prostacyclinsynthetase. PGI, is hydrolised to the inactive 6 keto PGF,a. PGI, is an inhibitor of plateletaggregation and a strong vasodilatator.

A thromboxane A 2 synthetase inhibitor retards hypertensive rat diabetic nephropathy

Spontaneously hypertensive rats (SHR) were injected with streptozotocin (STZ-SHR) to induce diabetes. The effect of DP-1904, a thromboxane A 2 synthetase inhibitor, on diabetic nephropathy was then studied by administering it for 5 months (1 or 10 mg/kg). DP-1904 did not affect renal 6-keto prostaglandin (PG)F 1α production in STZ-SHR, but markedly inhibited renal thromboxane (TX) B 2 production, so that the 6-keto PGF 1α/TXB 2 ratio was significantly increased (P < 0.05). STZ-SHR showed significant uraemia and proteinuria, plus increases in urinary γ-glutamyl-transpeptidase and urinary N-acetyl-β-glucosaminidase. DP-1904 significantly decreased (P < 0.01) the urinary changes. STZ-SHR also showed an increase in mesangial periodic acid-Schiff-positive substance and in relative renal weight, both of which were significantly inhibited by DP-1904 (P < 0.05). Thus, DP-1904 inhibited both TXB 2 production and the progression of renal damage in STZ-SHR.

Calicum channel blockers and prostaglandin generation by gastric surface epithelial cells

We investigated the effects of calcium channel blockers on generation of prostaglandin (PG) E 2 and 6-keto PGF 1α by gastric mucosal surface epithelium. Surface epithelial cells (SEC) isolated from rat gastric mucosa were incubated with either verapamil (1 or 10 μg/ml), diltiazem (2.5 or 25 μg/ml) or nifedipine (2.5 or 25 μg/ml) for 30 min at 37°C in calcium containing or calcium-free medium. Verapamil (both doses)_significantly incerased PGE 2 and 6-keto PGF 1α generation by the surface epithelial cells but only in calcium containing medium. Diltiazem did not affect PG gneration in calcium containing nor calcium-free medium. Nifedipine 25 μg/ml decreased PGE 2 but increased 6-keto PGF 1α generation. The inhibitory effect of nifedipine on GPE 2 generation was abolished in calcium-free medium, while the calmodulin antagonist did not affect verapamil-induced increase in PG generation.

Canine parainfluenza type 2 and Bordetella bronchiseptica infection produces increased bronchoalveolar lavage thromboxane concentrations in beagle puppies

Acute infections in beagle puppies with canine parainfluenza virus type 2 (CPI2), and CPI2 in combination with Bordetella bronchiseptica (Bb) produce bronchiolitis and increased airways responsiveness to aerosolized histamine during the acute infection. In order to determine whether these observations were associated with increased levels of eicosanoids, the stable metabolites of thromboxane A 2 and prostacylin, thromboxane B 2 (TXB 2) and 6-keto-prostaglandin F 1α (6-keto-PGF 1α) respectively, and leukotriene B 4 were measured in the bronchoalveolar lavage (BAL) fluid of 25 beagle puppies (age = 76 ± 1 days, mean ± SEM) 3–4 days after no infection (control, n = 6), inoculation with both CPI2 and Bb (CPI2-Bb, n = 11), inoculation with CPI2 alone (CPI2, n = 4), and inoculation with Bb alone (Bb, n = 4). In addition, plasma levels of TXB 2 and 6-keto-PGF 1α were measured before and after infection in the CPI2-Bb and control groups. The BAL concentration of thromboxane B 2 was increased in the CPI2-Bb group (520 ± 120 pg/ml), but not in the CPI2 (88 ± 40 pg/ml), Bb (235 ± 100 pg/ml), or control groups (120 ± 60 pg/ml, p < 0.01). There also was a borderline increase in BAL concentration of LTB 4 in the CP12-Bb group. No differences were observed in the BAL concentration of 6-keto PGF 1α. Furthermore, neither TXB 2 nor PGF 1α was elevated in the plasma of control or CPI2-Bb puppies. These data suggest that increased thromboxane concentrations in BAL fluid are associated with histamine hyperresponsiveness during acute infection in the CPI2-Bb group.

Tumor necrosis factor production by murine resident peritoneal macrophages is enhanced by dietary n−3 polyunsaturated fatty acids

Tumor necrosis factor (TNF) is a macrophage derived peptide that has an antitumor action and modulates immune and inflammatory reactions. Dietary fatty acids may modulate TNF production as dietary n−3 polyunsaturated fatty acids suppress human monocyte TNF production, but enhance its secretion by murine peritoneal macrophages. Mice were maintained for 5 weeks on diets containing different amounts of n−3 and n−4 fatty acids. TNF, PGE 2 and 6-keto PGF 1α production was monitored following in vitro stimulation of resident peritoneal macrophages with lipopolysaccharide. Macrophages from mice fed the high n−3 diet produced 8-fold more TNF and half the PGE 2 produced by macrophages from mice on the other diets. Indomethacin caused an increase in the TNF production by macrophages from mice on all diets but macrophages from mice on the high n−3 diet produced more TNF than macrophages from mice on the other diets. Exogenous PGE 2 (100 nM) greatly decreased TNF production by macrophages from mice on all diets, but macrophages from mice on the high n−3 diet secreted 70% more TNF than macrophages from mice fed the other diets, indicating that PGE 2 is only partly responsible for the effects observed. The results show that feeding n−3 polyunsaturated fatty acids may cause enhanced TNF production by resident peritoneal macrophages and that PGE 2 is partly responsible for the effect.

Effects of ozone on lung mechanics and cyclooxygenase metabolites in dogs

To determine if acute exposure to ozone can cause changes in the production of cyclooxygenase metabolites of arachidonic acid (AA) in the lung which are associated with changes in lung mechanics, we exposed mongrel dogs to 0.5 ppm ozone for two hours. We measured pulmonary resistance (R 1) and dynamic compliance (C dyn) and obtained methacholine dose response curves and bronchoalveolar lavagate (BAL) before and after the exposures. We calculated the provocative dose of methacholine necessary to increase R L 50% (PD 50) and analyzed the BAL for four cyclooxygenase metabolites of AA: a stable hydrolysis product of prostacyclin, 6-keto-prostaglandin F 1α (6-keto-PgF 1α); prostaglandin E 2 (PgE 2); a stable hydrolysis product of thromboxane A 2, thromboxane B 2 (TxB 2); and prostaglandin F 2α (PgF 2α). Following ozone exposure, R L increased from 4.75 +/- 1.06 to 6.08 +/- 1.3 cmH 2O/L/sec (SEM) (p < 0.05), C dyn decraesed from 0.0348 +/- 0.0109 to .0217 +/- .0101 L/cmH 2O (p < 0.05), and PD 50 decreased from 4.32 +/- 2.41 to 0.81 +/- 0.49 mg/cc (p<0.05). The baseline metabolite levels were as follows: 6-keto PgF 1α: 96.1 +/- 28.8 pg/ml; PgE 2: 395.8 +/- 67.1 pg/ml; TxB 2: 48.5 +/- 11.1 pg/ml; PgF 2α: 101.5 +/- 22.6 pg/ml. Ozone had no effect on any of these prostanoids. These studies quantify the magnitude of cyclooxygenase products of AA metabolism in BAL from dog lungs and demonstrate that changes in their levels are not prerequisites for ozone-induced changes in lung mechanics or airway reactivity.