Evaluation of 5-lipoxygenase inhibitors, zileuton, A-78773 and ICI-D-2138 in an ionophore (A-23187)-induced pleural inflammation model in the rat

Proteomic analysis of calcium-dependent secretion in Toxoplasma gondii

Toxoplasma gondii is an intracellular protozoan parasite that invades a wide range of nucleated cells. In the course of intracellular parasitism, the parasite releases a large variety of proteins from three secretory organelles, namely, micronemes, rhoptries and dense granules. Elevation of intracellular Ca(2+) in the parasite causes microneme discharge, and microneme secretion is essential for the invasion. In this study, we performed a proteomic analysis of the Ca(2+)-dependent secretion to evaluate the protein repertoire. We found that Ca(2+)-mobilising agents, such as thapsigargin, NH(4)Cl, ethanol and a Ca(2+) ionophore, A23187, promoted the secretion of the parasite proteins. The proteins, artificially secreted by A23187, were used in a comparative proteomic analysis by 2-DE followed by PMF analysis and/or N-terminal sequencing. Major known microneme proteins (MICs), such as MIC2, MIC4, MIC6 and MIC10 and apical membrane antigen 1 (AMA1), were identified, indicating that the proteomic analysis worked accurately. Interestingly, new members of secretory proteins, namely rhoptry protein 9 (ROP9) and Toxoplasma SPATR (TgSPATR), which was a homologue of a Plasmodium secreted protein with an altered thrombospondin repeat (SPATR), were detected in Ca(2+)-dependent secretion. Thus, we succeeded in detecting Ca(2+)-dependent secretory proteins in T. gondii, which contained novel secretory proteins.

Response of the isolated guinea pig bladder to exogenous and endogenous leukotrienes

Noninfectious urinary bladder inflammation is a poorly understood phenomenon, and the participation of leukotrienes (LTs) in the pathogenesis of bladder inflammation is unclear. Leukotrienes are synthesized by the bladder, and exogenous LTs induce contraction of isolated bladder segments. LTD4 and LTC4 were more potent contractile agents than LTE4. Leukotriene-induced contractions were blocked by ICI 198,615 (10(-6) M. and 10(-7) M.) a specific LT receptor antagonist. In the presence of indomethacin (5 x 10(-6) M.), bladder contraction in response to LTD4 was increased. Endogenous LT release was studied using an experimental model of cystitis. Antigen (ovalbumin 10(-6) to 10(-2) mg./ml.) challenge of bladder segments isolated from actively sensitized animals induced release of LT, prostaglandin D2 and histamine. A-64077 (Zileuton), a 5-lipoxygenase (5-LO) inhibitor, significantly reduced contraction of sensitized bladder tissue in response to antigen challenge in a concentration-dependent manner and abolished LT release. These data indicate that the guinea pig urinary bladder produces sulfidopeptide-LTs that can be released upon specific stimulation. Furthermore, LTs activate specific receptors promoting bladder contraction. Our findings suggest that specific 5-LO inhibitors or LT-receptor antagonists might be useful in treating or preventing bladder inflammation.