l-663536 and Chronic-Disease

The only Na-nutrient cotransporter described in mammalian small intestinal crypt cells is SN2/SNAT5, which facilitates glutamine uptake. In a rabbit model of chronic intestinal inflammation, SN2 stimulation is secondary to an increase in affinity of the cotransporter for glutamine. However, the immune regulation of SN2 in the crypt cells during chronic intestinal inflammation is unknown. We sought to determine the mechanism of regulation of Na-nutrient cotransporter SN2 by arachidonic acid metabolites in crypt cells. The small intestines of New Zealand white male rabbits were inflamed via inoculation with Eimeria magna oocytes. After 2-week incubation, control and inflamed rabbits were subjected to intramuscular injections of arachidonyl trifluoromethyl ketone (ATK), piroxicam and MK886 for 48 hrs. After injections, the rabbits were euthanized and crypt cells from small intestines were harvested and used.. Treatment of rabbits with ATK prevented the release of AA and reversed stimulation of SN2. Inhibition of cyclooxygenase (COX) with piroxicam did not affect stimulation of SN2. However, inhibition of lipoxygenase (LOX) with MK886, thus reducing leukotriene formation during chronic enteritis, reversed the stimulation of SN2. Kinetic studies showed that the mechanism of restoration of SN2 by ATK or MK886 was secondary to the restoration of the affinity of the cotransporter for glutamine. For all treatment conditions, Western blot analysis revealed no change in SN2 protein levels. COX inhibition proved ineffective at reversing the stimulation of SN2. Thus, this study provides evidence that SN2 stimulation in crypt cells is mediated by the leukotriene pathway during chronic intestinal inflammation.

Topics: Amino Acid Transport Systems, Neutral; Animals; Anti-Inflammatory Agents, Non-Steroidal; Arachidonic Acid; Arachidonic Acids; Chronic Disease; Coccidiosis; Eimeria; Enteritis; Enzyme Inhibitors; Gene Expression Regulation; Glutamine; Ileum; Indoles; Leukotrienes; Lipoxygenase; Lipoxygenase Inhibitors; Male; Prostaglandin-Endoperoxide Synthases; Rabbits; Sodium

Respiratory infection with Francisella tularensis (Ft) is characterized by a muted, acute host response, followed by sepsis-like syndrome that results in death. Infection with Ft establishes a principally anti-inflammatory environment that subverts host-cell death programs to facilitate pathogen replication. Although the role of cytokines has been explored extensively, the role of eicosanoids in tularemia pathogenesis is not fully understood. Given that lipoxin A

Topics: Acute Disease; Animals; Apoptosis; Arachidonate 5-Lipoxygenase; Bone Marrow Cells; Cell Death; Chemokines; Chronic Disease; Dinoprostone; Disease Susceptibility; Down-Regulation; Francisella tularensis; Immunity; Indoles; Inflammation Mediators; Leukotriene B4; Lipoxins; Macrophages; Metabolome; Mice, Inbred C57BL; Organ Specificity; Respiratory Tract Infections; Tularemia

Subcutaneous heat-coagulated egg white implants (EWI) induce chronic, intense local eosinophilia in mice, followed by asthma-like responses to airway ovalbumin challenge. Our goal was to define the mechanisms of selective eosinophil accumulation in the EWI model. EWI carriers were challenged i.p. with ovalbumin and the contributions of cellular immunity and inflammatory mediators to the resulting leukocyte accumulation were defined through cell transfer and pharmacological inhibition protocols. Eosinophil recruitment required Major Histocompatibility Complex Class II expression, and was abolished by the leukotriene B4 (LTB4) receptor antagonist CP 105.696, the 5-lipoxygenase inhibitor BWA4C and the 5-lipoxygenase activating protein inhibitor MK886. Eosinophil recruitment in EWI carriers followed transfer of: a) CD4+ (but not CD4-) cells, harvested from EWI donors and restimulated ex vivo; b) their cell-free supernatants, containing LTB4. Restimulation in the presence of MK886 was ineffective. CC chemokine receptor ligand (CCL)5 and CCL2 were induced by ovalbumin challenge in vivo. mRNA for CCL17 and CCL11 was induced in ovalbumin-restimulated CD4+ cells ex vivo. MK886 blocked induction of CCL17. Pretreatment of EWI carriers with MK886 eliminated the effectiveness of exogenously administered CCL11, CCL2 and CCL5. In conclusion, chemokine-producing, ovalbumin-restimulated CD4+ cells initiate eosinophil recruitment which is strictly dependent on LTB4 production.

Topics: Allergens; Animals; CD4-Positive T-Lymphocytes; Cell Movement; Chemokines; Chronic Disease; Dexamethasone; Eosinophilia; Eosinophils; Indoles; Inflammation; Leukotriene B4; Male; Mice; Mice, Inbred BALB C; Ovalbumin

The metabolism of arachidonic acid by the cyclooxygenase or lipoxygenase pathway generates eicosanoids, which have been implicated in the pathogenesis of various human diseases, including cancer. They are now believed to have important roles in tumor promotion, progression and metastasis. The involvement of lipoxygenase expression and function in tumor growth and metastasis has been reported in human tumor cell lines.. The expression of 5 and 12-lipoxygenase in patients with bladder tumor and chronic cystitis, and in normal bladder tissues was examined. We also examined the effects of their inhibitors on cell proliferation in a bladder cancer cell line. The expression of 5 and 12-lipoxygenase protein was detected by immunohistochemistry. The effects of lipoxygenase inhibitors on bladder cancer cell growth were examined by MTT (3-[4,5-dimethylthiazol-2-thiazolyl]-2,5-diphenyltetrazolium bromide) assay, while Hoechst (Sigma Chemical Co., St. Louis, Missouri) staining was used to determine whether lipoxygenase inhibitors induce apoptosis.. While slight 5 and 12-lipoxygenase expression was detected in chronic cystitis and normal bladder tissues, marked 5 and 12-lipoxygenase expression was detected in bladder cancer tissues. Lipoxygenase inhibitors caused marked inhibition of bladder cancer cells in a concentration and time dependent manner. Cells treated with lipoxygenase inhibitors showed chromatin condensation, cellular shrinkage, small membrane bound bodies (apoptotic bodies) and cytoplasmic condensation.. Lipoxygenase is induced in bladder cancer. Results suggest that lipoxygenase inhibitors may mediate potent antiproliferative effects against bladder cancer cells. Thus, lipoxygenase may become a new target in the treatment of bladder tumors.

Topics: Aged; Aged, 80 and over; Apoptosis; Arachidonate 12-Lipoxygenase; Arachidonate 5-Lipoxygenase; Carcinoma, Squamous Cell; Carcinoma, Transitional Cell; Cell Division; Chronic Disease; Cystitis; Female; Flavanones; Flavonoids; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Humans; Immunoenzyme Techniques; Indoles; Lipoxygenase Inhibitors; Male; Middle Aged; Neoplasm Staging; Reference Values; Reverse Transcriptase Polymerase Chain Reaction; Teprotide; Tumor Cells, Cultured; Urinary Bladder; Urinary Bladder Neoplasms