Leukotriene B

Individual genetic background together with environmental effects are thought to be behind many human complex diseases. A number of genetic variants, mainly single nucleotide polymorphisms (SNPs), have been shown to be associated with various pathological and inflammatory conditions, representing potential therapeutic targets. Prostaglandins (PTGs) and leukotrienes (LTs) are eicosanoids derived from arachidonic acid and related polyunsaturated fatty acids that participate in both normal homeostasis and inflammatory conditions. These bioactive lipid mediators are synthesized through two major multistep enzymatic pathways: PTGs by cyclooxygenase and LTs by 5-lipoxygenase. The main physiological effects of PTGs include vasodilation and vascular leakage (PTGE2); mast cell maturation, eosinophil recruitment, and allergic responses (PTGD2); vascular and respiratory smooth muscle contraction (PTGF2), and inhibition of platelet aggregation (PTGI2). LTB4 is mainly involved in neutrophil recruitment, vascular leakage, and epithelial barrier function, whereas cysteinyl LTs (CysLTs) (LTC4, LTD4, and LTE4) induce bronchoconstriction and neutrophil extravasation, and also participate in vascular leakage.

To examine the roles of leukotriene B4 (LTB4) and prostaglandin I2 (PGI2), the metabolites of arachidonic acid found in patients with sepsis, we measured the serum levels of LTB4 and a stable metabolite of PGI2, 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), in 22 patients with sepsis. Results were analyzed in relation to patients' survival. The serum levels of both LTB4 and 6-keto-PGF1 alpha were significantly higher in patients who died than in those who survived, thus serving as indicators of illness severity. There was a significant correlation between LTB4 and 6-keto-PGF1 alpha levels. The present study suggests that LTB4, a potent leukocyte activator, induces damage to vascular endothelial cells in patients with sepsis, resulting in the excessive production of PGI2 and, consequently, serious illness.

BACKGROUND: ;3,4-dihydroxycinnamic acid and its derivatives exhibit numerous biologic activities. Such activities have not previously been reported for 3,5-dihydroxycinnamic acid derivatives. In this study, ten derivatives of 3,5- dihydroxycinnamic acid were synthesized and their anti-inflammatory activities were tested in 12-O-tetradecanoylphorbol 13-acetate-induced mouse ear edema. Molecular biological studies have shed lights on their anti-inflammatory mechanism.;METHODS: ;Anti-inflammatory activities of ten new synthesized derivatives of 3,5-dihydroxycinnamic acid were tested in 12-O-tetradecanoylphorbol 13-acetate-induced mouse ear edema, and their anti-inflammatory mechanism was studied by ELISA, real-time RT-PCR, MPO assay and AA-induced mouse ear edema.;RESULTS: ;Compound 7 showed a pronounced anti-inflammatory effect and the inhibition rate was 65.6% at a dose of 1.6mg/ear. This compound acted by reducing mRNA and protein synthesis of tumor necrosis factor-α, interleukins 1β and 6, and also by decreasing the levels of activated neutrophil infiltrates. Furthermore, compound 7 significantly suppressed arachidonic acid-induced edema as well. Cell-based assays showed that compound 7 inhibited the production of cyclooxygenase- 2-catalyzed prostaglandin E2 from lipopolysaccharide-treated RAW 264.