12-hydroxy-5-8-10-14-eicosatetraenoic-acid and Keratitis

Increased production of 12-hydroxyeicosatetraenoic acid [12(R)-HETE] and 12-hydroxyeicosatrienoic acid [12(R)-HETrE] positively correlates with the in vivo progression of ocular surface inflammation in rabbits. Tear film was collected from human subjects with inflamed eyes to determine whether these eicosanoids could be detected from endogenous sources.. Control and inflamed eyes were assessed and assigned a subjective inflammatory score. Tears were collected and extracted with an internal standard. Single-ion-monitoring gas chromatography-mass spectrometry (SIM-GC-MS) was performed to quantitate endogenous levels of 12-HETE and 12-HETrE.. 12-HETrE was detected in the tear film of both control and inflamed eyes, with the mean level being seven times higher in inflamed tears. 12-HETE was not detected in control tears and was detected in only 6 of 38 inflamed-eye tear samples.. The current findings demonstrate that the human eye produces detectable amounts of 12-HETrE, which is released into the tear flow. The increased levels of 12-HETrE associated with ocular surface inflammation suggest that this eicosanoid may contribute to inflammation of the ocular surface in humans.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Arachidonic Acid; Conjunctivitis; Eye Foreign Bodies; Gas Chromatography-Mass Spectrometry; Humans; Inflammation; Iridocyclitis; Keratitis; Keratitis, Herpetic; Keratoconjunctivitis; Tears

The similar and overlapping activity of VEGF and the potent corneal-derived angiogenic eicosanoid 12(R)-HETrE calls for a study of the temporal relationship in the expression of these two autocoids. Since recent evidence suggests that hypoxia induces the expression of a CYP4B1 mRNA which might be involved in the conversion of arachidonic acid to 12(R)-HETrE, we determined its time-dependent expression and correlated it to that of VEGF mRNA in the rabbit model of closed eye contact lens-induced injury.. Rabbit eyes were fitted with contact lenses followed by a silk suture tarsorrhaphy. The anterior surface was analyzed at 2-, 4- and 7-days by slit lamp biomicroscopy, subjective inflammatory scoring and corneal pachymetry. Corneal epithelium was scraped and CYP4B1 and VEGF mRNA levels were measured by Southern hybridization of RT-PCR products amplified from a single cornea with specific primers.. Corneal thickness and inflammatory scores increased in a time dependent manner in the model of closed eye contact lens induced hypoxic injury. Corneal epithelial CYP4B1 and VEGF mRNAs, as well as the production of the angiogenic eicosanoid, 12-HETrE, increased in a time-dependent manner and correlated with the in situ inflammatory response.. The present study documents the increased expression of CYP4B1 isoform in the corneal epithelium during hypoxic injury in vivo. It also demonstrates the presence of VEGF mRNA in the corneal epithelium and its increased expression in this model of hypoxic injury. All together, the results of this study raise the possibility of interaction between these autocoids, VEGF and CYP4B1-12(R)-HETrE, in mediating the neovascularization response induced by the prolonged hypoxic state brought about by closed eye contact lens wear.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Animals; Aryl Hydrocarbon Hydroxylases; Blotting, Southern; Contact Lenses; Corneal Neovascularization; Cytochrome P-450 Enzyme System; DNA Primers; Endothelial Growth Factors; Epithelium, Corneal; Eyelids; Hypoxia; Keratitis; Lymphokines; Male; Microfilament Proteins; Models, Animal; Rabbits; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Time Factors; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors

To characterize a model of contact lens-induced corneal inflammation in the closed eye, with respect to inflammatory parameters and the metabolism of arachidonic acid by homogenates of the corneal epithelium.. Rabbit eyes were fitted with extended wear etafilcon A (58% water) hydrogel contact lenses in stacked fashion (two lenses per eye), followed by a silk suture tarsorrhaphy of approximately 90%. The anterior surface was analyzed over a 9-day period for inflammatory events through slit lamp biomicroscopy, subjective inflammatory scoring, corneal pachymetry, and corneal epithelial [1-(14)C]-arachidonic acid metabolism.. Hydrogel contact lens wear in the closed eye resulted in a progressive anterior surface inflammatory response correlated over time (r = 0.999). Central corneal thickness progressively increased and was also correlated to the inflammatory score (r = 0.995). [1-(14)C]-arachidonic acid metabolism by homogenates of the corneal epithelium resulted in the time-dependent formation of two major products, 12-hydroxyeicosatetraenoic acid (12-HETE) and 12-hydroxyeicosatrienoic acid (12-HETrE). Correlations were established between the synthesis of 12-HETE and 12-HETrE, the subjective inflammatory score (r = 0.963) and the progressive increase in corneal thickness (r = 0.971), over 9 days.. With this model of contact lens wear, eicosanoid synthesizing capacity of the corneal epithelium showed a time-dependent increase in the production of 12-HETE and 12-HETrE strongly correlating to the in situ inflammatory response. The relationship between 12-HETE and 12-HETrE synthesis and the degree of anterior surface inflammation implicate these eicosanoids, among others, as mediators of the inflammatory response to hydrogel contact lens wear in the closed eye.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Animals; Chromatography, High Pressure Liquid; Contact Lenses, Extended-Wear; Cornea; Corneal Edema; Cytochrome P-450 Enzyme System; Disease Models, Animal; Epithelium; Eyelids; Hydroxyeicosatetraenoic Acids; Keratitis; Male; Rabbits; Time Factors

The authors have previously shown a marked increase in corneal epithelial arachidonic acid metabolism to 12-hydroxyeicosatetraenoic acid (12-HETE) and 12-hydroxyeicosatrienoic acid (12-HETrE) in a model of closed eye-contact lens wear. Their formation was predominantly cytochrome P450-dependent and significantly correlated with inflammatory score and corneal thickness. In the current study, the authors used stannous chloride to inhibit the epithelial cytochrome P450-dependent synthesis of 12-HETE and 12-HETrE to assess the role of these eicosanoids as mediators of the inflammatory response to contact lens wear in the closed eye.. Hydrogel contact lenses were soaked in stannous chloride (100 micrograms/ml) or vehicle and fitted to the rabbit eye in stacked fashion (two lenses/eye), followed by a silk suture tarsorrhaphy of approximately 90%. Eyes were analyzed over a 7-day period for inflammatory responses through slit lamp biomicroscopy, subjective inflammatory scoring, ultrasonic pachymetry, and corneal epithelial [1-14C]-arachidonic acid metabolism.. Closed eye-hydrogel contact lens wear resulted in a progressive anterior surface inflammatory response. Coinciding with these events was a time-dependent increase in corneal thickness and 12-HETE and 12-HETrE production rates by corneal epithelial homogenates. Treatment of the lenses with stannous chloride (100 micrograms/ml) significantly attenuated by day 7 the inflammatory score (56% decrease), corneal thickness (17% decrease), and 12-HETE and 12-HETrE synthesis (77% and 71% decrease, respectively).. This study further substantiates the involvement of cytochrome P450, through the synthesis of 12-HETE and 12-HETrE, in the inflammatory response associated with hydrogel contact lens wear in the closed eye. Thus, inhibition of cytochrome P450, with subsequent decreases in 12-HETE and 12-HETrE, may attenuate the pathophysiologic response to contact lens wear in the closed eye.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Animals; Contact Lenses, Extended-Wear; Cornea; Corneal Edema; Cytochrome P-450 Enzyme Inhibitors; Cytochrome P-450 Enzyme System; Disease Models, Animal; Drug Delivery Systems; Epithelium; Eyelids; Hydroxyeicosatetraenoic Acids; Keratitis; Male; Rabbits; Time Factors; Tin Compounds