leukotriene-b4 and Keratitis

The objective of this study was to establish and characterize the invasion of polymorphonuclear leukocytes (PMNs) into a normal cornea after intrastromal injection of the tripeptide chemoattractants generated from alkali-degraded corneas.. The following samples were injected into the midstroma of normal rabbit corneas: ultrafiltered tripeptide chemoattractants (N-acetyl-proline-glycine-proline and N-methyl-proline-glycine-proline) generated from alkali-degraded corneas, synthetic N-acetyl-PGP, positive control (leukotriene B4 [LTB4]), or negative control (Hanks' balanced salt solution [HBSS]). Timed responses of PMN infiltration were established for effective concentrations of LTB4 or the ultrafiltered chemoattractants.. All intrastromal injections resulted in the immediate development of an edematous disc that was 10 mm in diameter. The lesion essentially had cleared in the HBSS-injected eyes by 8 hours, and histologic sections revealed minimal numbers of PMNs in the cornea or limbal tissue. The injection of LTB4 or the ultrafiltered tripeptide chemoattractants induced peak numbers of PMNs within the stroma at 8 hours, subsiding by 16 hours. Seventy units of ultrafiltered chemoattractants yielded a strong PMN response, similar to 1 X 10(-5) M LTB4. The highest concentration of ultrafiltered chemoattractants (350 U) produced a severe PMN response that was characterized by a solid sheet of neutrophils surrounding the injection site. The injection of synthetic N-acetyl-PGP (2 X 10(-4) M) produced a marked PMN response.. PMN invasion of the normal cornea after the injection of the ultrafiltered tripeptide chemoattractants or the synthetic N-acetyl-PGP mimicked early PMN infiltration in the alkali-injured eye, confirming the importance of this chemoattractant as an inflammatory mediator.

Topics: Animals; Burns, Chemical; Chemotactic Factors; Chemotaxis, Leukocyte; Corneal Stroma; Disease Models, Animal; Eye Burns; Humans; Injections; Keratitis; Leukocyte Count; Leukotriene B4; Neutrophils; Oligopeptides; Rabbits; Sodium Hydroxide

Contact lens induced acute red eye (CLARE) and contact lens induced peripheral ulcer (CLPU) are among the most common contact lens induced inflammatory reactions. Both CLARE and CLPU are characterized by corneal infiltration which indicates the presence of chemoattractants and other inflammatory mediators. The aim of this study was to characterize the cytokine and chemotactic lipid inflammatory mediator profile in the tears of people experiencing CLARE or CLPU. Cytokines IL-1 beta, IL-6, IL-8, GM-CSF and LTB4 in tears were measured by antibody sandwich and competition inhibition enzyme-linked immunosorbent assays (ELISA). Platelet activating factor-like activity was measured by a degranulation assay by measuring the release of labelled serotonin from platelets. The functional role GM-CSF and chemoattractants were determined by flow cytometry and chemotaxis. Increased levels of cytokines and chemoattractants were detected in both CLARE and CLPU tears. CLPU tears showed increased levels of LTB4 (P = 0.002) and PAF-like activity (P = 0.047) whereas CLARE tears showed increased levels of GM-CSF (P = 0.002). IL-8 (P < 0.05). LTB4 (P = 0.002) and PAF-like activity (P = 0.047) compared to control tears. Flow cytometric analysis revealed that incubation of PMN with CLARE tears increased the number of IgA receptors indicating that the GM-CSF in CLARE tears was active. Combinations of suboptimal concentrations (which were found in CLARE and CLPU tears) of IL-8 with either LTB4 or PAF significantly (P < 0.0001) enhanced the chemotactic activity for PMN compared to their individual effects. Our data highlight the possible pathophysiological roles of these inflammatory mediators in leukocyte recruitment and activation during ocular inflammatory responses. The results suggests that GM-CSF, IL-8 and LTB4 are active during corneal pathology and LTB4 or IL-8 may maintain the contact lens induced PMN response in vivo.

Topics: Acute Disease; Analysis of Variance; Cells, Cultured; Contact Lenses; Corneal Ulcer; Cytokines; Dose-Response Relationship, Drug; Flow Cytometry; Granulocyte-Macrophage Colony-Stimulating Factor; Humans; Inflammation Mediators; Interleukin-8; Keratitis; Leukotriene B4; Lipids; Neutrophil Activation; Neutrophils; Platelet Activating Factor; Receptors, Fc; Tears

The present studies have demonstrated the levels of N-methyl histamine in tears from normal physiological states, pathological states and contact lens wear. Histamine was significantly increased in closed eye tears compared with both open and reflex tears. Tears from other ocular conditions had low levels of histamine except for environmental hypersensitivity, which contained significantly elevated levels compared to normal tear types. Interestingly, tears from asymptomatic contact lens wearers had significant levels of histamine whereas tears from contact lens adverse events had lower levels, possibly reflecting a change in histamine metabolism.

Topics: Analysis of Variance; Conjunctivitis, Allergic; Contact Lenses; Enzyme-Linked Immunosorbent Assay; Humans; Inflammation Mediators; Interleukin-6; Keratitis; Leukotriene B4; Methylhistamines; Tears

The effect of rabbit vitreous with endotoxin-induced uveitis was investigated for its role in the modulation of rat corneal neovascularization (NV). Elvax pellets implanted into at cornea contained either uveitic vitreous, intact vitreous or Elvax alone. The latter two kinds of pellets did not elicit NV. Uveitic vitreous pellets caused, in 100% of eyes, a persistent NV with maximal growth on the 10th day post implantation. Prostaglandin E2 and leukotriene B4 levels in the uveitic rabbit vitreous at 36 h postendotoxin injection were 7- and 5-fold higher than baseline, respectively. Histopathologically, the neovascularized cornea showed a significant inflammatory reaction attributable to the uveitic vitreous extract.

Topics: Animals; Cornea; Corneal Neovascularization; Dinoprostone; Drug Implants; Endotoxins; Escherichia coli; Female; Keratitis; Leukotriene B4; Male; Polyvinyls; Rabbits; Uveitis; Vitreous Body

To examine the activity of myeloperoxidase (MPO) and the concentrations of the proinflammatory metabolites of arachidonic acid (AA) in ocular tissue of mice that are either capable or incapable of restoring corneal clarity during an intraocular Pseudomonas aeruginosa infection.. For a period of 11 days after infection, whole eyes were enucleated and homogenized in buffer from mice given only an initial infection as well as from mice given a subsequent infection in the previously uninfected eye either 4 or 8 weeks after the initial infection. Tissue-free supernatants from the ocular homogenates were used for the determination of MPO activity by quantitating the conversion of specific substrate by spectrophotometric methods and for the quantitation of AA metabolites by ELISA:. Overall, animals reinfected at 4 and 8 weeks had a lower inflammatory response when compared to the mice given only the initial infection. The lowest levels of LTB4 and MPO activity, indicators of PMN involvement, were observed in the the 8-week reinfected mice, which restored corneal clarity in an enhanced manner.. These results suggest that induced ocular PMN responses may play a role, in part, in the inflammatory response leading to the tissue destruction observed during ocular P. aeruginosa infection.

Topics: Animals; Arachidonic Acid; Cornea; Dinoprostone; Enzyme-Linked Immunosorbent Assay; Eye Infections, Bacterial; Female; Keratitis; Leukocyte Count; Leukotriene B4; Mice; Mice, Inbred C57BL; Neutrophils; Peroxidase; Pseudomonas Infections; Thromboxane B2

Natural and synthetic inflammatory compounds were implanted in the corneas of rabbits to clarify the question whether corneal neovascularization is induced by stromal edema alone, or by neovascular mediators. It could be demonstrated that prostaglandin E1 and E2 have an angiogenetic capacity, whereas their precursor (arachidonic acid) as well as PGA1, A2, B2, I2 and Thromboxan A2 were inactive in this regard. Histology showed that corneal neovascularization is always accompanied by the invasion of polymorphonuclear leukocytes. Corneal edema in the beginning of vascularization can be explained by the activities of PGE (vasodilation, increase of vascular permeability, liberation of histamine). The implantation of lipoxygenase-dependent arachidonic acid compounds (5-HETE, Leukotriene B4) demonstrated that these mediators share in the process of neovascularization by inducing the chemotaxis. The above mentioned activities of prostaglandins and leukotrienes could also be demonstrated following penetrating keratoplasty and alkali burns of the anterior segment inducing extensive corneal neovascularization. An analysis of the prostaglandin- and leukotriene-dependent mechanisms could be achieved by selective PG- and LT-inhibitors. Radioimmunoassays showed a definite correlation between the concentrations of PGE and the amount of neovascularization following alkali burns. The results of our research lead to the following scheme of pathophysiology of corneal neovascularization: hypoxic, chemical, thermic and mechanical alterations of the cornea induce an activation of corneal cytomembranes, thus initiating the cyclooxygenase-dependent synthesis of prostaglandins with consecutive vasodilation and increase of vascular permeability as well as histamine liberation resulting in corneal edema; on the other hand, prostaglandins proved to have a minimal chemotactic activity; the lipoxygenase-dependent synthesis of leukotrienes inducing chemotaxis and diapedesis of polymorphonuclear leukocytes into the corneal stroma. These inflammatory cells are then the main source of newly synthesized leukotrienes maintaining the chemotaxis, and prostaglandins with angiogenetic activity. Cyclooxygenase- and lipoxygenase-inhibitors can inhibit these activities at two different levels, leading to an approach of successful therapy of corneal diseases inducing neovascularization.

Topics: Animals; Arachidonic Acid; Arachidonic Acids; Burns, Chemical; Cornea; Corneal Injuries; Corneal Transplantation; Eye Burns; Female; Keratitis; Leukotriene B4; Lipoxygenase; Male; Neovascularization, Pathologic; Prostaglandin-Endoperoxide Synthases; Prostaglandins; Rabbits; Thromboxane A2