MMP-9 and the perioperative management of LASIK surgery.

PURPOSE OF REVIEW: Hyperosmolarity is a central mechanism causing ocular surface inflammation and eye irritation in typical patients suffering from tear dysfunction. Tear composition in dry eyes, or dysfunctional tear syndrome, may destabilize the tear film and cause ocular surface epithelial disease. Increased activity of matrix metalloproteinases (MMPs), especially MMP-9, plays a critical role in wound healing and inflammation and is primarily responsible for the pathologic alterations to the ocular surface that leads to a dysfunctional tear state. RECENT FINDINGS: Altered corneal epithelial barrier function is the cause for ocular irritation and visual morbidity in dry eye disease. The increased MMP-9 activity in dry eyes may contribute to deranged corneal epithelial barrier function, increased corneal epithelial desquamation, and corneal surface irregularity. SUMMARY: Dry eye is one of the most common complications of photorefractive keratectomy and laser in-situ keratomileusis (LASIK). LASIK has both a neurotrophic effect on the cornea and leads to a physical change in corneal shape that results in a change in tear dynamics, leading to ocular surface desiccation. The reduction in tear function after LASIK may induce an increase in osmolarity and consequently raise the concentration of proinflammatory cytokines and MMP-9 in the tear film, which results in dry eyes and insufficient attachment between the corneal flap and the corneal bed. Appropriate diagnosis and management of dysfunctional tear syndrome may lead to less postoperative LASIK complications.

Overexpression of matrix metalloproteinase-1 (MMP-1) and MMP-3 in superior limbic keratoconjunctivitis.

PURPOSE: To explore the presentations of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) in superior limbic keratoconjunctivitis (SLK) with typical redundant superior conjunctiva. METHODS: Eight surgical specimens from medically refractory SLK patients were examined. Another nine conjunctival specimens from patients who underwent cataract and retinal surgery served as controls. Expression of RNA and proteins of MMPs and TIMPs in conjunctival specimens and cultured conjunctival fibroblasts were determined by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry (IHC). RESULTS: The expression of mRNA of MMP-1 and -3 was detected in six and seven SLK patients, respectively, but was not detected in any case in the control group. IHC showed more prominent immunostaining of MMP-1 and -3 in the subepithelial stroma of the SLK patients than in the controls. After culturing, conjunctival fibroblasts of the SLK patients also shown apparent overexpression of MMP-1 and -3 compared with that in the controls. MMP-9 was not detected in both groups. MMP-2 and TIMP-1 and -2 were detected in some cases in both groups without a statistically significant difference between groups. CONCLUSIONS: Overexpression of MMP-1 and -3 was found in surgical specimens and cultured conjunctival fibroblasts from SLK patients. MMP imbalance may contribute to SLK pathogenesis. (ClinicalTrials.gov number, NCT00167050.).

Metalloproteinases in canine experimental traumatic keratoconjunctivitis.

Matrix metalloproteinases (MMPs) are thought to be involved in eye disease and may be present in tears. MMP activity was measured by gelatine zymography. Active gelatinase levels were determined by a gelatine degradation ELISA. Potential MMP-9 (gelatinase-B) monomer enzyme activity was elevated (P < 0.001) in keratoconjunctivitis in comparison to normal tears. MMP-9, dimer form, enzyme activity was elevated (P < 0.001) in fluids from keratoconjunctivitis cases in comparison to fluids from normal eyes. Significant increases in gelatinase bioactivities were seen in tears from keratoconjunctivitis disease cases (P < 0.01). Enzymes in dogs with eye disease were biologically active indicating that both the active forms of the enzyme were present. Hence, they could be an important indicator in deterioration of the cornea during eye disease.

Tear malate dehydrogenase, lactate dehydrogenase and their isoenzymes in normal Chinese subjects and patients of ocular surface disorders.

PURPOSE: To determine levels of malate dehydrogenase (MDH), lactate dehydrogenase (LDH) and their isoenzymes in tears of normal Chinese subjects and patients with ocular surface disorders. METHODS: The age range of normal subjects was 10-88, with 136 male and 128 female subjects. 123 patients suffered from ocular surface disorders. Tears were collected from lower fornix on Xinghua filter disc (0.1mm thick, 5mm in diameter). The values of tear MDH and LDH were determined by MONARCH-2000 Analyzer (U. S. A.). Their isoenzymes were separated by acetate cellulose electrophoresis and were determined by Model CDS-200 light densitometer. RESULTS: The normal values of tear LDH and MDH were 45.51 + 23.00-81.35 + 37.84 umol.s-1/L and 11.00 + 5.33-19.50 + 9.17 umol.s-1/L respectively, disregarding sex or eye distriction (P > 0.05). The values of tear LDH and MDH in the group aged 10-19 were significantly lower than in another groups (P < 0.05). 95% normal ranges of tear MDH aged below 19 and above 20 were 3.63-19.90 umol.s-1/L and 4.20-36.64 umol s-1/L. 95% normal ranges of tear LDH aged below 19 and above 20 were 17.69-82.93 umol.s-1/L and 21.47-150.41 umol.s-1/L. The MDH isoenzymes comprised MDHs and MDHm, the former accounting for 80.0-89.1%. The LDH isoenzymes comprised 5 varieties, of which the ratio H/M of subunit H to subunit M was 0.196 + 0.02. Levels of tear LDH,MDH and their isoenzymes in different diseases were various. CONCLUSIONS: Tear LDH/MDH ratio reflected sensitively the metabolism of corneae and conjunctival epithelium. The changes in LDH isoenzymes were helpful to the differential diagnosis of external eye diseases, and the increase of MDHm reflected sensitively the degree of injury to the corneal epithelium.

Human conjunctival mast cells: distribution of MCT and MCTC in vernal conjunctivitis and giant papillary conjunctivitis.

The distribution and concentration of human tryptase-positive, chymase-negative mast cells (MCTS) and tryptase-positive, chymase-positive mast cells (MCTCS) were examined in conjunctival biopsy specimens from subjects with active vernal conjunctivitis (VC; n = 7), giant papillary conjunctivitis (GPC; n = 6), and allergic conjunctivitis (AC; n = 5), and from asymptomatic soft-contact lens wearers (SCL; n = 6) and normal control individuals (n = 19). Carnoy's fixed tissue sections were stained by a double immunohistochemical method using a biotinylated mouse monoclonal antichymase antibody with immunoperoxidase, followed by an alkaline phosphatase-conjugated mouse monoclonal antitryptase antibody. Epithelial mast cells (MCs) were found in all VC specimens (96% MCTCs) and in three GPC specimens (100% MCTCS) but in none of the other groups. In the substantia propria, MCTCS were the predominant type of MC observed in all specimens, accounting for 95% of the total MCs in the normal control group and 100% of the total MCs in the subjects with GPC, AC, and SCL. No significant differences were found in the total MC concentration of the substantia propria among the normal control subjects (11,054 +/- 6327 MCs per cubic millimeter), subjects in the SCL group (13,168 +/- 4685 MCs per cubic millimeter), subjects with GPC (17,313 +/- 8500 MCs per cubic millimeter), and subjects with AC (15,380 +/- 5660 MCs per cubic millimeter). In subjects with VC, the percentage of MCTs (18% +/- 13%) and the total MC concentration (24,689 +/- 18,978 MCs per cubic millimeter) in the substantia propria were significantly increased as compared to the normal control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Tear lysozyme measurements in chronic blepharitis.

Tear lysozyme concentrations were measured on 47 patients with chronic blepharitis and 22 normal control patients. The patients consisted of 26 individuals with various types of chronic blepharitis alone and 21 individuals with chronic blepharitis and clinically-diagnosed keratoconjunctivitis sicca (KCS). The mean lysozyme concentration of blepharitis patients without KCS (4070 micrograms/ml) was not significantly different from normals (3760 micrograms/ml). However, mean lysozyme concentration of the blepharitis patients with KCS (2530 micrograms/ml) was significantly lower than normals or blepharitis patients without KCS (p less than 0.01). It was concluded that tear lysozyme deficiency does not play a significant role in the etiology of chronic blepharitis. However, a large percentage of patients with chronic blepharitis were found to have KCS.

Immunochemical determination of human tear lysozyme (muramidase) in keratoconjunctivitis sicca.

Radial immunodiffusion was tested as an alternative for the agar diffusion assay for lysozyme in tear fluid. The influence of interactions between lysozyme and agarose or filter paper, used for sample collection, on the results of the immunodiffusion test was investigated. In 100 tear samples from 50 healthy volunteers and average lysozyme concentration of 1.9 g/l was found. Lysozyme values obtained by both methods in the tear fluid of a group of 78 volunteers, ranging from healthy individuals to severe keratoconjunctivitis sicca patients were compared. A lower limit of normal at 1.1 g/l was found by the radial immunodiffusion assay.

Investigation of the accuracy of tear lysozyme determination by the Quantiplate method.

The accuracy of lysozyme concentration determination by the method of measuring lysis diameter in agarose gel slabs containing Micrococcus lysodeikticus bacteria uniformly suspended throughout the gel was determined for various methods of tear sample collection. The effects of storage of lysozyme solution samples at subzero temperatures for several days was also examined. It was found that a power rather than the suggested exponential dependence between the lysozyme concentration and lysis diameter provides the most accurate fit and thus should be used for interpolation. Storing samples frozen in glass capillaries lowered the lysozyme concentration in a predictable manner. When Weck-Cel sponges were used to collect the samples the lysozyme concentration was greatly diminished in a nonlinear manner because of internal adsorption. The relative loss (cause by adsorption) depended on the actual lysozyme concentration as well as on the sample volume/sponge weight ratio. Storing samples absorbed by such sponges in a frozen state further altered the results in an unpredictable way. The observation that smaller tear samples for a given sponge size yielded lower apparent values for lysozyme concentration casts doubt on findings that have reported lower lysozyme concentration in the tears of keratoconjunctivitis sicca patients, where either cellulose sponges or filter paper discs were used for tear collection.

Quantitative tear lysozyme assay: a new technique for transporting specimens.

We have developed a method for assaying the concentration of tear lysozyme using eluates of tear fluid collected on filter paper discs. Specimens can be stored and transported to remote laboratories for assay. We have shown that the 'indirect' or eluate method gives statistically comparable results to the 'direct' method using fresh, neat tear fluid.