Prostaglandins, leukotrienes, and essential fatty acids最新文献

The objective of this study was to investigate the effects of alpha-linolenic acid (18:3n-3) and linoleic acid (18:2n-6) on the fatty acid composition and the activity and release of mast cell mediators in the canine mastocytoma cell line C2. Cells were cultured in Dulbecco's modified Eagle's medium mixed with 50% Ham's F12 (containing linoleic acid 0.14 micro M). The basic medium (DEH) was supplemented with 0.14 micro M alpha-linolenic acid. 14.0 micro M alpha-linolenic acid (DEH-n-3) or 14.0 micro M linoleic acid (DEH-n-6) was added. Eight days after culturing of C2 in DEH-n-3 we measured elevated levels of n-3 fatty acids up to 22:3. The tryptase activity and the stimulated PGE2 production and histamine release were reduced. In contrast, after culturing of C2 in DEH-n-6 we determined elevated levels of n-6 fatty acids up to 20:3, increased tryptase activity and stimulated histamine release. Thus 18:3n-3 has anti-inflammatory effects in cultured canine mastocytoma cells.

The fatty acid composition of serum phospholipids (PL) and cholesteryl esters (CE) in 26 healthy pregnant women at the end of term and 1 and 3 days after delivery was analysed in order to determine whether the maternal serum fatty acid composition changes in the early puerperium. The composition of the saturated fatty acids significantly changes in the PL fraction: 16:0 decreased and 18:0 increased. Both 20:4n-6 and 20:5 n-3 significantly increased after parturition in serum PL while 22:6n-3 remained constant at the three sampling time points. The sum of HUFA was slightly higher 3 days postpartum compared to the prepartum data. The essential fatty acid index significantly increased after delivery. In the CE fraction too differences occurred during puerperium: 18:2n-6 and 20:4n-6 increased and 18:1n-9 decreased after parturition. The sum of the n-3 fatty acids in CE remained unaltered. The EFA index significantly improved both in PL as in CE after delivery. In conclusion, the previously reported changes in the fatty acid composition of PL and CE during normal pregnancy diminish shortly after delivery. In fact, very soon after delivery the maternal fatty acid composition returns to more normal values.

In an attempt to investigate the significance of lipid peroxidation in the pathogenesis of gastritis associated with or without Helicobacter pylori infection, malonodialdehyde (MDA) levels were measured by the thiobarbiturate assay in the gastric juice of 101 patients undergoing upper GI endoscopy and correlated with histopathological findings. Elevated MDA levels were found in all patients with gastritis compared with controls. MDA levels were significantly correlated with the extent of the mucosal inflammation and with disease activity in patients with reactive gastritis. In patients with H. pylori associated gastritis MDA levels were not correlated with disease activity but rather with the degree of atrophy. In this case, MDA levels were equal or even less than in patients with reactive gastritis. MDA levels were not affected by the history of consumption of PPIs, of H(2)-blockers or of NSAIDs over the last month before the endoscopy. It is concluded that lipid peroxidation is a mechanism involved in the pathogenesis of gastritis associated or not to H. pylori infection.

Thromboxan A(2) (TXA(2)) is the main product of arachidonic acid metabolism in activated platelets. Platelet-released supernatants (PRS) can induce osteoclast-like cell formation in murine bone marrow cultures via a cyclooxygenase (COX)/receptor activator of NF-kB-ligand (RANKL)-dependent pathway. Here we investigated a possible linkage between platelet-released TXA(2) and osteoclastogenesis. The stable analog of TXA(2), carbocyclic TXA(2) (CTXA(2)) can induce the formation of tartrate-resistant acid phosphatase positive multinucleated cells in murine bone marrow cultures via a RANKL-dependent pathway and requires the presence of stromal cells. Interestingly, the platelet-released instable TXA(2) does not account for osteoclastogenic effects as: (a) PRS-induced osteoclastogenesis in the presence of the TXA(2) receptor antagonist SQ29548; (b) inhibition of platelet TXA(2) synthesis by indomethacin and acetylsalicylic acid failed to decrease the osteoclastogenic potential of the corresponding supernatants; and (c) CTXA(2)-induced osteoclast-like cell formation independent of indomethacin and the selective COX-2 inhibitor NS398.

Whether the reported gestation-dependent increase in cyclooxygenase activity in gestational tissues is due to an accumulation of cyclooxygenase in vivo or an increasing capacity to synthesize cyclooxygenase in vitro is unknown. In this study in guinea pigs, COX activity was estimated from the net production rates of prostaglandins E(2) and F(2alpha) in the presence of optimal substrate concentrations. Cyclooxygenase activity in amnion increased between 45 days of gestation and labor in microsomes (150-fold in relation to PGF(2alpha) production and 116-fold in relation to PGE(2) production) and in tissue explants (42-fold in relation to PGF(2alpha) production). The capacity for de novo synthesis of cyclooxygenase after aspirin treatment increased nine-fold between 45 days of gestation and labor in amnion explants. Comparison of COX activity in amnion explants with or without prior aspirin treatment showed that COX activity is at least three-fold higher in controls than would be expected if the activity was due to de novo synthesis alone. Cyclooxygenase-2 mRNA predominated in amnion but neither cyclooxygenase-2 nor cyclooxygenase-1 mRNA levels (semi-quantitative RT-PCR) changed significantly. This suggests that the gestation-dependent increase in cyclooxygenase activity in guinea pig amnion is due in part to accumulation of cyclooxygenase in vivo, that COX-2 predominates, and that COX activity is not correlated with levels of COX mRNA.

Hepatorenal syndrome (HRS) is a peculiar form of progressive renal failure complicating the course of cirrhosis and ascites. The renal impairment of HRS is merely functional and potentially reversible. Notwithstanding, in spite of several encouraging attempts, a satisfactory medical treatment for HRS is still expected. Several pathophysiological mechanisms are active in HRS. Arachidonate metabolism derangements are among these, and prostaglandins and thromboxane antagonists have been tried with variable outcomes. Also leukotrienes (LT) appear to be involved in HRS. Three drugs (zileuton, montelukast and zafirlukast) interfering with LT synthesis and receptor binding are currently available, but they have not yet been tried in HRS. Accordingly, the author would like to suggest physicians engaged in care of these critical patients to consider a trial with these drugs-as well as with any future innovative agent active on the arachidonate-derived metabolic pathways.

In the present study, we investigated the effect of nitric oxide (NO) and prostaglandins (PGs) on the production of arachidonate and L-arginine metabolites. We found that in the estrogenized rat uterus lipopolysaccharide (LPS) 5mg/kg induced NO and PGs synthesis simultaneously. The uteri were incubated with different doses of an NO donor: NP 300 and 600 microM. The results indicate that both doses of NP produce a significant increase (P<0.01) in all prostanoids evaluated. The stimulatory effect was completely reversed by the addition of 2 microg/ml of hemoglobin (Hb), an NO scavenger. However, NOS inhibitor, N(G)-L-monomethyl arginine had no effect on basal prostanoid production. We also studied NO synthesis in the presence of different PGs concentration. We found that PGF(2alpha) and PGD(2) were capable of reversing LPS stimulation on NO synthesis (P<0.05), in all the doses evaluated. On the other hand, PGE(2) 10(-10) and 10(-9)M potentated LPS effect (P<0.001). These results suggest that in the estrogenized rat uterus, the synthesis of cyclooxygenase metabolites is positively regulated by NO, while NO synthesis regulation depends on the PGs evaluated.

Recombinant monoclonal antibodies specific for 11-dehydro-thromboxane B(2) (11D-TX) were isolated from the combinatorial libraries on a pComb3 phage-display vector using a magnetic cell sorting (MACS) system. The libraries were constructed from repertories of light and heavy-chains derived from the total RNA of 11D-TX conjugated keyhole limpet haemocyanin-immunized mice. Biotinylation of 11D-TX conjugated bovine serum albumin (BSA) was performed through free thiol groups on BSA using 1-biotinamido-4-[4'-(maleimidomethyl) cyclohexanecarboxamido] butane (Biotin-BMCC). Affinity bio-panning was performed to enrich the phage display libraries against biotinylated 11D-TX conjugated BSA with the MACS system. Results indicated that the selected anti-11D-TX Fab fragments expressed by E. coli exhibited a five-fold higher affinity for BSA conjugated 11D-TX compared to BSA alone and little specificity to other related compounds as determined by the binding assay and inhibition enzyme-linked immunosorbent assay (ELISA). This is the first report of an antibody against prostaglandin produced by phage display technology and also determination of the DNA sequence of this antibody. The MACS system was shown to be a simpler and more efficient method of panning than the conventional ELISA procedure. According to our results, we concluded that the phage display technique combined with the MACS system allowed the selection of the antibody with high affinity and some specificity.

The effects of the lysophospholipids, sphingosine-1-phosphate (S1P) and lysophosphatidic acid (LPA) were studied in human primary osteoblastic cells and the human osteosarcomal cell lines, G292 and MG-63. The studies focused on the role of the Gi protein in the regulation of S1P and LPA-induced proliferation, the effects of the phospholipids on alkaline phosphatase, an early marker of osteoblastic cell proliferation, and the presence of edg receptors. Proliferation was assessed by 3H-thymidine incorporation. Short-term incubation with S1P or LPA induced increases in proliferation that were attenuated in the presence of the Gi inhibitor, pertussis toxin. Alkaline phosphatase activity was measured with a spectrophotometric assay. Biphasic effects of S1P and LPA were observed with the nature of the response dependent upon the cell type, concentration of test agent and the time period of incubation. RTPCR studies revealed that edg-1,2,4,5 receptors are present in the primary normal osteoblastic cells, the MG63 and G292 cells. Only the G292 cells expressed the edg-3 receptor to any significant extent.