leukotriene-b4 and Uveitis--Anterior

Endotoxin-induced uveitis (EIU) is a model that mimics human acute anterior uveitis. Cyclooxygenase (COX)-2 is an enzyme that initiates the conversion of arachidonic acid (AA) into prostaglandins (PGs), whereas 5-lipoxygenase (5-LO) generates leukotrienes (LT). The purpose of this study was to delineate the role of COX-2 in acute ocular inflammation.. EIU was induced in wild-type (WT), heterozygotic (COX-2(+/-)) and COX-2 null (COX-2(-/-)) mice by injection of lipopolysaccharide (LPS). Other mice were coinjected with LPS and IFN gamma. Ocular histology, serum cytokines, and AA products determined by ELISA, and relevant ocular messengers determined by RT-PCR were compared among the different groups.. Histology showed that the EIU score was significantly enhanced in COX-2(-/-) mice in comparison to WT and COX-2(+/-). PGE(2) was increased in WT and COX-2(+/-) EIU but not in COX-2(-/-) EIU. LTB(4) in serum and ocular 5-LO transcripts were increased in COX-2(-/-) EIU mice in comparison with WT and COX-2(+/-) EIU mice. IL-6 increased, whereas IFN gamma decreased both in serum and ocular transcripts in COX-2(-/-) EIU mice in comparison with WT and COX-2(+/-). Furthermore, EIU was suppressed in mice treated with recombinant IFN gamma, as shown by the decreased EIU scores, the presence of serum LTB(4) and IL-6 and ocular 5-LO and IL-6 mRNA, and the increases in serum IFN gamma and ocular IFN gamma, particularly in COX-2(-/-) mice.. These data suggest that disturbance of the AA pathway exacerbates EIU in COX-2-deficient mice. IFN gamma moderately reverses this exacerbation and protects against EIU.

Topics: Animals; Arachidonate 5-Lipoxygenase; Arachidonic Acid; Cyclooxygenase 2; Dinoprostone; Enzyme-Linked Immunosorbent Assay; Interferon-gamma; Interleukin-6; Isoenzymes; Leukotriene B4; Lipopolysaccharides; Mice; Mice, Knockout; Prostaglandin-Endoperoxide Synthases; Recombinant Proteins; Reverse Transcriptase Polymerase Chain Reaction; Salmonella typhimurium; Uveitis, Anterior

To investigate the role of endothelin receptors (ET(A) and ET(B)) in the inflammatory reaction induced by endothelin-1 (ET-1), the time course of changes in aqueous protein concentration (APC) after the intravitreal injection of ET-1 (10(-4), 10(-5) M) was measured using a laser flare-cell meter in pigmented rabbit eyes. The effects of pre-treatment with specific ET(A) receptor antagonist (97-139) (10(-1), 10(-2), 10(-3), 10(-4) M), specific ET(B) receptor antagonist (BQ-788) (1.6 x 10(-3) M), and vehicle solution were assessed. The influence of ET(A)receptor antagonist pre-treatment on aqueous prostaglandin E(2) and leukotriene B(4) concentrations was also evaluated. As a result, pre-treatment with ET(A) receptor antagonist blocked the APC increase induced by 10(-4) M ET-1 in a dose dependent fashion, while BQ-788 did not suppress the inflammatory reaction. The injection of ET-1 increased aqueous prostaglandin E(2) concentration, which was inhibited by pre-treatment with ET(A) receptor antagonist. Aqueous leukotriene B(4) concentration was not affected by ET-1 nor ET(A) receptor antagonist. In conclusion, ET(A) receptor mediates the increases in aqueous protein and prostaglandin E(2) concentration induced by ET-1 injection, and this inflammatory reaction occurs via the cyclooxygenase pathway of arachidonic acid cascade.

Topics: Animals; Caffeic Acids; Dinoprostone; Endothelin Receptor Antagonists; Endothelin-1; Eye Proteins; Female; Leukotriene B4; Male; Oleanolic Acid; Oligopeptides; Piperidines; Rabbits; Receptors, Endothelin; Uveitis, Anterior

To investigate the characteristics of anterior chamber inflammatory reaction induced by intravitreal injection of endothelin-1 (ET-1).. The time course of changes in aqueous protein concentration (APC) after intravitreal injection of 10(-4), 10(-5), 10(-6) and 10(-7) M ET-1 into rabbit eyes was measured with a laser flare-cell meter. The influence of a topical diclofenac sodium (DFNa) pre- and post-treatment was assessed. Aqueous prostaglandin E2 and leukotriene B4 concentration was quantified using a radioimmunoassay technique.. Intravitreal injection of 10(-4) and 10(-5) M ET-1 significantly increased APC, while 10(-6) and 10(-7) M ET-1 did not induce anterior chamber inflammation. After 10(-5) M ET-1 injection, APC reached a maximum at 4 h post-treatment and returned to a normal level 48 h after injection. Eyes treated with 10(-4) M ET-1 displayed a bi-phasic time course, with peak values observed 4 to 8 h as well as 48 h after administration. Pre- and post-treatment with topical DFNa completely suppressed the APC increase in the 10(-5) M ET-1 preparation, and considerably inhibited it in the 10(-4) M ET-1 preparation. After ET-1 injection, aqueous prostaglandin E2 concentration increased significantly, followed by an increase in APC. There were no changes in leukotriene B4 concentration.. ET-1 induces anterior chamber inflammation via the cyclooxygenase pathway of the arachidonic acid cascade. The lipoxygenase pathway is not involved in this reaction.

Topics: Administration, Topical; Animals; Anterior Chamber; Aqueous Humor; Cyclooxygenase Inhibitors; Diclofenac; Dinoprostone; Endothelin-1; Eye Proteins; Female; Inflammation; Injections; Leukotriene B4; Male; Rabbits; Radioimmunoassay; Uveitis, Anterior; Vitreous Body

Anti-inflammatory actions of dexamethasone (DEXA), Cyclosporin A (CSA) and Rapamycin (RAPA) were assessed on uveitis induced by intravitreal E-coli Endotoxin (100ng) in rabbits at 24 hrs. In this model, endotoxin caused a breakdown of the blood-aqueous barrier (BAB) and polymorphonuclear neutrophils (PMN) infiltration into the aqueous humor (AH) and iris-ciliary body (ICB). Intramuscular (I.M.) DEXA (2mg/kg) but not topical DEXA (0.1% 6 x daily) inhibited AH leukocytes and protein level. However, both routes caused an inhibition of AH Prostaglandin E2 (PGE2) and Leukotriene B4 (LTB4). In the ICB, I.M. DEXA significantly inhibited PGE2 synthesis and myeloperoxidase (MPO) activity. I.M. CSA (25mg/kg) and I.M. RAPA (10mg/kg) inhibited the AH leukocytes and protein content and MPO activity in the ICB. RAPA also inhibited AH protein and eicosanoid (except AH LTB4) levels in both the AH and ICB. Interestingly, castor oil, a vehicle of CSA, also inhibited AH leukocytes and the release of PGE2 into AH and from ICB. In summary, systemic administration of DEXA and other immunosuppressive drugs CSA and RAPA significantly inhibited endotoxin-induced uveitis in rabbits.

Topics: Animals; Aqueous Humor; Ciliary Body; Cyclosporine; Dexamethasone; Dinoprostone; Disease Models, Animal; Endotoxins; Immunosuppressive Agents; Iris; Leukocyte Count; Leukotriene B4; Neutrophils; Peroxidase; Polyenes; Rabbits; Sirolimus; Uveitis, Anterior

The authors tested the hypothesis that platelet-activating factor (PAF) and cyclooxygenase metabolites of arachidonic acid mediate the ocular inflammatory response to intravitreally injected tumor necrosis factor-alpha (TNF alpha). Rabbits were treated with the PAF receptor antagonist SRI 63-441, the cyclooxygenase inhibitors indomethacin and naproxen, or SRI 63-441 and indomethacin. At 24 hr after intravitreal injection of TNF (20,000 U), the severity of inflammation was assessed based on iridal hypermia, aqueous humor leukocyte number and aqueous humor protein, immunoreactive-prostaglandin E (I-PGE), and leukotriene B4 (LTB4) concentrations. Although all of the treatments significantly reduced the severity of anterior uveitis, SRI 63-441 plus indomethacin was the most effective, indomethacin and naproxen were intermediately effective, and SRI 63-441 was the least effective. The results of this study are consistent with an important role for cyclooxygenase metabolites of arachidonic acid in the inflammatory response to TNF alpha, particularly with respect to dilation of iridal blood vessels. Although naproxen was nearly as effective as indomethacin in reducing aqueous humor I-PGE levels, indomethacin conferred significantly more protection to the blood-aqueous barrier as shown by lower protein levels in the aqueous humor. Thus, although cyclooxygenase inhibition may partially explain the protection afforded the blood-aqueous barrier by these nonsteroidal anti-inflammatory agents, the data suggest that indomethacin may also exert anti-inflammatory effects that are independent of cyclooxygenase inhibition. Furthermore, the data are consistent with TNF alpha releasing PAF in the eye and PAF acting both directly, by increasing vascular permeability, and indirectly, by promoting release of cyclooxygenase and lipoxygenase metabolites of arachidonic acid.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Aqueous Humor; Eicosanoids; Eye Proteins; Indomethacin; Leukocyte Count; Leukotriene B4; Male; Naproxen; Platelet Activating Factor; Prostaglandins E; Quinolinium Compounds; Rabbits; Recombinant Proteins; Tumor Necrosis Factor-alpha; Uveitis, Anterior; Vitreous Body

Inflammation induced by systemic injection of endotoxin can be a good model for endogenous uveitis since ocular inflammation is induced without manipulating the eye. We carried out morphological and biochemical studies in Lewis rats to evaluate the breakdown of the blood-ocular barrier following injection of endotoxin (1 mg/rat) in footpads. Vasodilation was observed as early as 3 hours and became maximum at 18-24 hours after the injection. Unlike in the eye, no inflammatory changes were observed in other organs. Protein and cell contents in the aqueous humor increased significantly as early as 3 hours after the injection and reached a peak level at 24 hours. The protein content returned to the normal level in the following several days, while cells in the aqueous humor remained at a high level even 1 week after the injection. The time-course of the pupillary size was very similar to that of the protein concentration. Furthermore, we examined leukotrienes (LTs) levels in aqueous humor by high-pressure liquid chromatography. LTD4 was detected in the aqueous humor at 6 hours and reached its peak level at 24 hours. The present data indicates that the systemic injection of endotoxin causes the disruption of the blood-ocular barrier soon after the injection and inflammation becomes maximum in 18-24 hours. This model can be used for studying endogenous uveitis and the disruption of the blood-ocular barrier without direct trauma to the eye.

Topics: Animals; Aqueous Humor; Chromatography, High Pressure Liquid; Disease Models, Animal; Dose-Response Relationship, Immunologic; Endotoxins; Injections; Leukotriene B4; Male; Rats; Rats, Inbred Lew; Retina; Shigella flexneri; Time Factors; Uveitis; Uveitis, Anterior