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Biomedical subjects

M E Fini

Publications and source records attributed to M E Fini.

At least 37 records · Page 2Linked to original sources
PubMed1997

Frog PNKT-4B cells express specific extracellular matrix-degrading enzymes and cytokines correlated with an invasive phenotype.

A temperature-dependent metastatic phenotype reported for a frog cell line, PNKT-4B, provided a means for studying potential mediators of cell-matrix interaction involved in metastatic invasion. Zymography revealed that these cells secreted enzyme species with properties and characteristics of mammalian metalloproteinases: collagenase, stromelysin, gelatinase A, and gelatinase B. These enzymes were produced by PNKT-4B cultures maintained at both invasive-permissive (28 degrees C), and invasion-restrictive (20 degrees C) temperatures. However, under the invasive-permissive culture condition cells produced more of the putative gelatinase B and A enzymes. In addition, an activated form of gelatinase A was produced only in invasion-permissive cultures. DNA synthesis bioassays (Mv1Lu cell line and mouse thymocytes) to detect growth promoting and/or inhibitory cytokines, revealed that PNKT-4B cultures kept at 28 degrees C released significantly higher levels of stimulatory (interleukin-1-like) and latent inhibitory (transforming growth factor-beta-like) substances into the medium compared to 20 degrees C cultures. Pre-absorption of media samples with heparin-sepharose indicated a second stimulatory cytokine as well. A corneal fibroblast bioassay that tests for mediators of collagenase synthesis, detected a stimulatory substance whose activity was greatly reduced in the presence of interleukin-1 receptor antagonist protein. Collagenase stimulatory activity present in 28 degrees C culture medium was significantly higher than equal samples from 20 degrees C cultures. These studies provide a molecular correlation between release of cytokines with properties of the metastatic phenotype seen in vivo. They further provide some of the first characterizations of frog MMPs and cytokines, which are likely to be involved in other tissue remodeling events.

Animals↗
PubMed1997

Perspectives on eye development.

The lens of the vertebrate eye was the classic model used to demonstrate the concepts of inductive interactions controlling development. However, it is in the Drosophila model that the greatest progress in understanding molecular mechanisms of eye development have most recently been mode. This progress can be attributed to the power of molecular genetics, an approach that was once confined to simpler systems like worms and flies, but is now becoming possible in vertebrates. Thus, the use of transgenic and knock-out gene technology, coupled with the availability of new positional cloning methods, has recently initiated a surge of progress in the mouse genetic model and has also led to the identification of genes involved in human inherited disorders. In addition, gene transfer techniques have opened up opportunities for progress using chick, Xenopus, and other classic developmental systems. Finally, a new vertebrate genetic model, zebrafish, appears very promising for molecular studies. As a result of the opportunities presented by these new approaches, eye development has come into the limelight, hence the timeliness of this focus issue of Developmental Genetics. In this introductory review, we discuss three areas of current work arising through the use of these newer genetic approaches, and pertinent to research articles presented herein. We also touch on related studies reported at the first Keystone Meeting on Ocular Cell and Molecular Biology, recently held in Tamarron Springs, Colorado, January 7-12, 1997.

Animals↗
PubMed1997

Regulation of paracrine cytokine balance controlling collagenase synthesis by corneal cells.

PURPOSE: Classic studies have demonstrated that corneal epithelial cell density in culture can alter the balance of stimulatory and inhibitory cytokines controlling the elaboration of collagenolytic activity by co-cultured stromal cells. The current study attempts to bring the understanding of this mechanism to a molecular level. METHODS: A rabbit primary corneal cell culture model was used. RESULTS: Using molecular probes that bind to and neutralize specific cytokines, a major stimulator for stromal cell collagenase synthesis released by corneal epithelial cells into culture medium was identified as interleukin-1 alpha (IL-1 alpha), and a secondary stimulator was characterized as a heparin-binding cytokine. An inverse relationship between net collagenase stimulatory activity and epithelial cell plating density was demonstrated. In contrast, the release of inhibitory activity for IL-1-stimulated collagenase synthesis was not subject to the cell density effect. Direct measurement of IL-1 alpha protein levels revealed that this cytokine was released much more efficiently on a per cell basis when cells were plated at low density than when they were plated at high density. The effect was not caused by greater cell lysis at low cell density and was mediated only partially by changes at the IL-1 alpha synthesis level. CONCLUSIONS: These data provide evidence that epithelial cells release stimulatory cytokines for collagenase expression more efficiently when they have limited contact with their neighbors and that this has important consequences for the overall paracrine cytokine balance controlling collagenase synthesis. Alteration of the paracrine cytokine balance by changes in cell contact may be an important means for regulating epithelial-stromal interactions involved in corneal development and repair.

Animals↗
PubMed1997

Repair phenotype in corneal fibroblasts is controlled by an interleukin-1 alpha autocrine feedback loop.

PURPOSE: To explore the role of autocrine interleukin-1 alpha (IL-1 alpha) as a central regulator of the repair phenotype in corneal fibroblasts. METHODS: Disruption of the actin cytoskeleton with cytochalasin B (CB), which mimics changes in shape that occur in repair tissues, was used to stimulate repair gene expression in early-passage fibroblasts. Changes in expression of IL-1 alpha, IL-8, collagenase, and ENA-78 were determined by Northern blot analysis, radioimmunoassay, and an enzyme-amplified sensitivity immunoassay (EASIA). Expression of repair genes was also examined in repair fibroblasts, isolated from healing, penetrating keratectomy wounds in rabbits. RESULTS: Blocking IL-1 alpha activity prevented both constitutive and stimulated increases in synthesis of IL-8 and collagenase in early-passage cultures of corneal fibroblasts, demonstrating the role of IL-1 alpha as a necessary intermediate for expression of these genes. Evidence is also presented that the IL-1 alpha autocrine controls expression of an IL-8 related factor, ENA-78. Unlike early-passage fibroblasts, fibroblasts freshly isolated from the uninjured cornea did not express IL-1 alpha. However, fibroblasts freshly isolated from remodeling corneal repair tissue 3 weeks after injury were found to express substantial levels of IL-1 alpha, regulated through an autocrine feedback loop. Neutralization experiments demonstrated that the IL-1 alpha autocrine is largely responsible for controlling both collagenase and IL-8 synthesis in repair fibroblasts, as it is in early-passage fibroblasts. CONCLUSIONS: These findings provide evidence that activation of an autocrine IL-1 alpha feedback loop is an important mechanism by which fibroblasts adopt a repair phenotype during remodeling of the cornea.

Animals↗
PubMed1996

Regionalized growth patterns of young chicken corneas.

PURPOSE: Extracellular matrix (ECM) accumulation, synthesis, and degradation were compared in central and peripheral corneal regions of 3-week-old chicks to identify regional differences within the cornea. METHODS: For collagen accumulation experiments, corneas were isolated at the scleral junction, the epithelium was removed, and the central corneal region was isolated from the peripheral region with a 3 mm trephine. After corneal stromas were digested with proteinase K, aliquots were used to estimate total collagen from hydroxyproline and cell number from DNA measurements. For biosynthesis experiments, corneas were placed in organ culture containing either in 3H-thymidine, 3H-proline, or 35SO4. After radiolabeling, the epithelium was removed, central and peripheral regions were isolated, and each corneal sample was analyzed for incorporated radioactivity. Gelatinolytic species present in each corneal region were compared qualitatively by gelatin zymography. RESULTS: Measurement of hydroxyproline content indicated that the central corneal stroma contained significantly more collagen per DNA than the peripheral corneal region (+40%, P = 0.013) and incorporated significantly higher levels of 3H-thymidine/ng DNA (+92%, P < 0.001), 3H-proline/ng DNA (+980%, P = 0.004), and 35SO4/ng DNA (+650%, P = 0.01) than the peripheral corneal region. Results of gelatin zymography indicated that the central cornea contained the proenzyme form of gelatinase A, whereas the peripheral cornea contained both the proenzyme form and the active form of gelatinase A. CONCLUSIONS: Fibroblasts located in the central cornea have a significantly higher rate of proliferation and ECM production than those of the peripheral cornea, whereas the presence of active gelatinase only in the peripheral cornea suggests higher gelatinolytic activity and ECM turnover in the periphery.

Animals↗
PubMed1996

Role of matrix metalloproteinases in failure to re-epithelialize after corneal injury.

Delayed re-epithelialization of the cornea after injury usually precedes stromal ulceration. Previous findings using a rat thermal injury model suggested that re-epithelialization is impeded by products of resident corneal cells, which destroy adhesive structures at the basement membrane zone. In this study, we provide additional evidence for this concept. Failure to re-epithelialize was found to correlate with an increase in the amounts of gelatinolytic matrix metalloproteinases present in the rat cornea. One of these gelatinases, gelatinase B, is synthesized by the resident corneal cells, and inhibitions of its synthesis correlated with inhibition of basement membrane dissolution. The matrix metalloproteinases collagenase and stromelysin are also synthesized by resident corneal cells in thermally injured corneas of rabbits, but the timing of bulk enzyme synthesis correlated more closely with deposition of repair tissue in the stroma than with failure to re-epithelialize. Nevertheless, in human corneas with repair defects, gelatinase B and collagenase are synthesized by cells in the basal layer of the epithelium directly adjacent to the basement membrane, suggesting that both could participate in dissolution of this structure. Importantly, treatment of thermally injured corneas with a synthetic inhibitor of matrix metalloproteinases significantly improved basement membrane integrity. These data support the concept that over-expression of matrix metalloproteinases by resident corneal cells impedes re-epithelialization after some types of corneal injury.

Animals↗
PubMed1995

Competence for collagenase gene expression by tissue fibroblasts requires activation of an interleukin 1 alpha autocrine loop.

The enzyme collagenase (EC 3.4.24.7), a key mediator in biological remodeling, can be induced in early-passage fibroblasts by a wide variety of agents and conditions. In contrast, at least some primary tissue fibroblasts are incompetent to synthesize collagenase in response to many of these stimulators. In this study, we investigate mechanisms controlling response to two of the conditions in question: (i) trypsin or cytochalasin B, which disrupt actin stress fibers, or (ii) phorbol 12-myristate 13-acetate (PMA), which activates growth factor signaling pathways. We demonstrate that collagenase expression stimulated by trypsin or cytochalasin B is regulated entirely through an autocrine cytokine, interleukin 1 alpha (IL-1 alpha). The IL-1 alpha intermediate also constitutes the major mechanism by which PMA stimulates collagenase expression, although a second signaling pathway(s) contributes to a minor extent. Elevation of the IL-1 alpha level in response to stimulators is found to be sustained by means of an autocrine feedback loop in early-passage fibroblast cultures. In contrast, fibroblasts freshly isolated from the tissue are incompetent to activate and sustain the IL-1 alpha feedback loop, even though they synthesize collagenase in response to exogenous IL-1. We conclude that this is the reason why tissue fibroblasts are limited, in comparison with subcultured fibroblasts, in their capacity to synthesize collagenase. Activation of the IL-1 alpha feedback loop, therefore, seems likely to be an important mechanism by which resident tissue cells adopt the remodeling phenotype.

Actins↗
PubMed1995

A corneal epithelial inhibitor of stromal cell collagenase synthesis identified as TGF-beta 2.

PURPOSE: To determine the molecular mechanisms whereby substances released by corneal epithelial cells act to inhibit the elaboration of collagenolytic activity by corneal stromal cells and to determine whether inhibitory activity might be mediated by interleukin-1 receptor antagonist (IL-1ra) or transforming growth factor (TGF)-beta. METHODS: Conditioned media were generated from primary cultures of rabbit corneal epithelial cells, from passaged cultures of rabbit corneal stromal fibroblasts, and from cells of the rabbit corneal epithelial cell line, SIRC. Pure populations of stromal cells were isolated from rabbit cornea and used directly for bioassay of the conditioned media to detect substances that inhibit collagenase synthesis. The mink lung epithelial cell line, Mv1Lu, was used for bioassay of TGF-beta-like activity. The addition of specific neutralizing antisera to bioassays allowed an assessment of the contribution of each isoform to the net regulatory activity. Reverse transcription-polymerase chain reaction and Northern blot analysis were employed to detect the presence of IL-1ra or TGF-beta mRNA species in cells from cultures used to generate conditioned media. RESULTS: Both stimulatory and inhibitory substances that regulate the synthesis of stromal cell collagenase are released by corneal epithelial cells in primary culture. In contrast, only stimulatory activity is produced by corneal fibroblasts or SIRCs. MRNAs for a TGF-beta isoform, TGF-beta 2, and IL-1ra were identified in epithelial cells. Stromal fibroblasts also expressed TGF-beta 2 mRNA, but no evidence was found for expression of TGF-beta 3 mRNA in any of the three cell types. TGF-beta 2 is released by epithelial cells in both active and latent forms. This cytokine mediates the major portion of the net inhibitory activity against stromal cell collagenase synthesis produced by corneal epithelial cells. CONCLUSIONS: This study demonstrates the expression of TGF-beta 2 and IL-1ra by corneal epithelial cells in culture. It is the TGF-beta 2 that acts as the major inhibitor of collagenase synthesis by corneal stromal cells in culture. However, IL-1ra and TGF-beta 2 are likely to play important roles in epithelial-mesenchymal interactions regulating corneal development, homeostatic maintenance, and repair.

Animals↗
PubMed1995

Unique regulation of the matrix metalloproteinase, gelatinase B.

PURPOSE: The matrix metalloproteinase (MMP), gelatinase B, is expressed by both corneal cell types found at the epithelial-stromal tissue interface, the site of basement membrane repair in the healing cornea. This study investigates the relative regulation of gelatinase B compared to other MMPs in response to agents related to those found in the corneal repair environment or in corneal ulcers. METHODS: A culture model of corneal cells isolated from rabbit was used. RESULTS: Gelatinase B is the major MMP expressed by corneal epithelial cells, whereas stromal fibroblasts produce gelatinase B along with three other MMPs: collagenase, stromelysin, and gelatinase A. Phorbol-12-myristate 13-acetate (PMA) stimulates gelatinase B mRNA and protein synthesis by corneal cells, which is similar to its effect on the other MMPs. Stimulation occurs, at least partially, at the transcriptional level. PMA-stimulated MMP expression follows biphasic kinetics, with the major effect on collagenase, stromelysin, and gelatinase A occurring during the late component. In contrast, the major gelatinase B response occurs during the early component. Transforming growth factor-beta (TGF-beta) has no effect on constitutive expression of gelatinase B by fibroblasts; however, expression stimulated by PMA is enhanced. In contrast, constitutive expression of collagenase and stromelysin is inhibited by TGF-beta. However, in the presence of PMA, the initial inhibitory effect of TGF-beta is reversed after treatment. CONCLUSION: Gelatinase B expression is regulated differently from other corneal MMPs. This provides a mechanism for control of basement membrane repair independent of repair processes in the stroma.

Animals↗
PubMed1994

The rabbit gene for 92-kDa matrix metalloproteinase. Role of AP1 and AP2 in cell type-specific transcription.

We isolated the rabbit gene for the 92-kDa matrix metalloproteinase, gelatinase B, and sequenced 1802 contiguous bases covering the first three exons and 522 bases of DNA upstream of the start site for transcription. The DNA between bases -519 and +19 is sufficient to drive expression of a reporter gene in early passage cultures of corneal fibroblasts or primary cultures of corneal epithelial cells. Basal activity of the gelatinase B promoter in fibroblasts is lower than a collagenase promotor of 1800 base pairs, but activity of both promotors is similarly stimulated by treatment of transfected cells with phorbol 12-myristate 13-acetate, and stimulation is enhanced by co-treatment with transforming growth factor-beta. In contrast, basal activity of the gelatinase B promotor in epithelial cells is higher than the collagenase promotor. Deletion analysis demonstrated that sequences upstream of base -330 confer cell type-specific activity to the gelatinase B promotor. Site-directed mutagenesis revealed that an AP1-like element within this region is specifically utilized by fibroblasts. This region also contains elements that confer the capacity for activation by AP2, a transcription factor found to be expressed by corneal epithelial cells but not by corneal fibroblasts. In contrast, AP2 does not activate the collagenase promotor. These results provide a molecular basis for the unique cell type-specific expression pattern of gelatinase B as compared to other matrix metalloproteinases.

Animals↗
PubMed1994

Interleukin 1 alpha mediates collagenase synthesis stimulated by phorbol 12-myristate 13-acetate.

Stimulation of collagenase expression in cultures of normal diploid fibroblasts by the tumor promotor phorbol 12-myristate 13-acetate (PMA) occurs secondarily to synthesis of unknown intermediary proteins. We have investigated the hypothesis that a form of the cytokine interleukin 1 (IL-1) is one intermediate controlling PMA-stimulated collagenase expression. Treatment with an IL-1 receptor antagonist inhibits the constitutive synthesis of collagenase in early passage fibroblast cultures from rabbit. Radioimmunoassay demonstrates that, of the two known IL-1 forms, IL-1 alpha and IL-1 beta, only IL-1 alpha is synthesized and released into the medium of corneal fibroblast cultures. PMA treatment of cells increases the level of IL-1 alpha mRNA; this occurs prior to the increase in collagenase mRNA and corresponds with increased synthesis and release of IL-1 alpha protein. Neutralizing antiserum to IL-1 alpha inhibits constitutive collagenase synthesis. Reagents that inhibit the activity of IL-1 alpha (IL-1 receptor antagonist or neutralizing antibody) also inhibit the PMA-mediated stimulation of collagenase synthesis. These results indicate that constitutive and PMA-stimulated expression of collagenase is regulated through an IL-1 alpha intermediate. In vivo, regulation of the lytic phase of tissue remodeling through the IL-1 alpha intermediate may ensure the recruitment of cells adjacent to the one that received the initial stimulus.

Achilles Tendon↗
PubMed1993

Stromal fibroblasts synthesize collagenase and stromelysin during long-term tissue remodeling.

The process of connective tissue remodeling is an important mechanism contributing to tissue morphogenesis in development and homeostasis. Although it has long been known that remodeling tissues actively mediate collagenolysis, little is understood about the molecular mechanisms controlling this cell-regulated process. In this study, we examined the biosynthesis of collagenase and the related metalloproteinase, stromelysin, during remodeling of repair tissue deposited after mechanical injury to the rabbit cornea. Neither enzyme was synthesized by uninjured corneas; however, synthesis and secretion was detectable within one day after injury. Collagenase accumulated in its latent form while stromelysin appeared to be partially activated. Enzymes were synthesized by cells having a fibroblast phenotype. These cells were found within the stroma. New synthesis was correlated with accumulation of enzyme-specific mRNA. Highest levels of enzyme synthesis were observed in the repair tissue. However, stromal cells outside of the repairing area also synthesized both enzymes. The level of synthesis decreased in a gradient radiating from the repair tissue. Total synthetic levels in a given area of cornea were dependent on both the number of cells expressing enzyme and the rate of enzyme synthesis. Synthesis of collagenase was detected in repair tissue as long as nine months after injury. Our findings provide direct support for the hypothesis that new collagenase synthesis by cells in repair tissue is the first step in collagen degradation during long-term tissue remodeling.

Animals↗
PubMed1993

MMPs and proteinase inhibitors in the human aqueous humor.

PURPOSE: This study was performed to examine the gelatinolytic and caseinolytic activities and the levels of two proteinase inhibitors, alpha 1-proteinase inhibitor (alpha 1-antitrypsin) and alpha 2-macroglobulin, in the human aqueous humor. METHODS: Aqueous humor samples were collected during elective surgery in patients with cataracts. Zymography with gelatin- and casein-containing gels was performed. The inhibitors were examined by Western blot analyses, enzyme-linked immunosorbent assay, and dot blot assays. RESULTS: The aqueous humor contained a major band of gelatinolytic activity at a molecular weight of 66 kD and minor bands at 125, 95, and 62 kD. These gelatinases were inhibited by 10 mM ethylenediaminetetraacetic acid (EDTA) or 1,10-phenanthroline. After extended incubation (48 hours), zymography on casein-containing gels showed proteinase bands with molecular weights in the 80- to 84-kD range. Additional bands at 68 and 48 kD also were observed. All the caseinase activities were inhibited by 10 mM phenylmethylsulfonyl fluoride and 1 microgram/ml aprotinin. No inhibition was observed with 5 mM EDTA, 5 microM E-64, or 1 microM pepstatin. These results indicated that the caseinases are serine proteinases. Western blot analysis showed a 53-kD alpha 1-proteinase inhibitor band in the aqueous humor. The concentration was 32.2 +/- 9.9 micrograms/ml, constituting approximately 15% of the total protein. A 360-kD protein band immunoreactive to anti-alpha 2-macroglobulin also was detected. Its level in the aqueous humor was 3.2 +/- 1.3 micrograms/ml. CONCLUSIONS: The gelatinases, serine-like proteinases, and proteinase inhibitors found in the aqueous humor may participate in the remodeling of extracellular matrices in the trabecular meshwork and other tissues bordering the anterior chamber.

Aged↗
PubMed1992

Collagenolytic/gelatinolytic enzymes in corneal wound healing.

We have documented changes in expression of collagenolytic/gelatinolytic enzymes of the matrix metalloproteinase family (MMP) in healing or ulcerating corneal wounds of rat or rabbit. Correlation of our findings with specific changes in the extracellular matrix of the repair tissue suggests two different roles for the enzymes, MMP-2 and MMP-9. MMP-2 is expressed in undamaged corneal stroma where it may degrade the occasional collagen molecule that becomes damaged. After corneal wounding, expression of this enzyme is increased and much of it appears in the active form. These changes persist for at least seven months, suggesting that MMP-2 is involved in the prolonged process of collagen remodelling in the stromal repair tissue. MMP-9 is expressed in the epithelial layer of repair tissue with a timing suggesting it might participate in controlling resynthesis of the basement membrane. MMP-9 also appears to be involved in degradation of the epithelial basement membrane that precedes corneal ulceration.

Animals↗
PubMed1992

Collagenolytic/gelatinolytic metalloproteinases in normal and keratoconus corneas.

Cells of keratoconus corneas have been reported to produce higher levels of collagenolytic/gelatinolytic enzymatic activities than do cells of normal corneas. The current study investigates the contribution of 1) specific enzyme gene products, and 2) the degree to which these proteins are present in the activated forms, to the increased enzymatic activities. We demonstrate that two neutral gelatinolytic enzymes, a 66/59 kD form and a 92 kD form, can be directly extracted from both normal and keratoconus corneas. These enzymes are identified as the pro- and activated forms of MMP-2 and as the pro-form of MMP-9, specific members of the matrix metalloproteinase family. Normal and keratoconus corneas show no significant differences in amounts or types of extractable neutral gelatinases, nor in the amounts or types that they synthesize in culture. Furthermore, in both the normal and keratoconus corneas, gelatinases are found primarily in the inactive form. These studies suggest the possible importance of changes in proteinase inhibitor levels to the characteristic biochemical features of keratoconus corneas.

Adolescent↗
PubMed1991

Differential roles for two gelatinolytic enzymes of the matrix metalloproteinase family in the remodelling cornea.

We have documented changes in collagenolytic/gelatinolytic enzymes of the matrix metalloproteinase family (MMP) in remodelling rabbit cornea. MMP-2 (65 kDa gelatinase) in the proenzyme form is synthesized by the cells of the normal corneal stroma. After keratectomy the level of MMP-2 is increased in the stroma and enzyme appears in both pro- and activated forms. In addition, corneal cells synthesize MMP-9 (92 kDa gelatinase) in the proenzyme form after keratectomy; expression occurs in both the epithelial as well as stromal corneal layers. Changes in expression of both enzymes are precisely localized to the repairing portion of cornea, but demonstrate important differences in timing that correlate with the timing of specific events of matrix remodelling. Our data suggest that each of the gelatinases plays a different role in tissue remodelling after injury. We hypothesize that MMP-2 performs a surveillance function in normal cornea, catalyzing degradation of collagen molecules that occasionally become damaged. After wounding, this enzyme appears to participate in the prolonged process of collagen remodelling in the corneal stroma that eventually results in functional regeneration of the tissue. MMP-9 expression does not correlate with stromal remodelling, but we suggest that the enzyme might play a part in controlling resynthesis of the epithelial basement membrane.

Animals↗
PubMed1991

Transforming growth factor-beta and interleukin-1 modulate metalloproteinase expression by corneal stromal cells.

The enzyme collagenase participates in remodeling the extracellular matrix of corneal stroma during normal wound healing and mediates the degradation of extracellular matrix that occurs in many corneal pathologic states. Because this enzyme is synthesized and secreted by corneal cells, therapy of degradative disorders might be geared toward control of enzyme expression. The effects of two cytokines, transforming growth factor-beta (TGF-beta) and interleukin-1 (IL-1), on the expression of collagenase by cultured corneal stromal cells are reported. In addition, the concomitant effects of these cytokines on expression of three additional members of the matrix metalloproteinase (MMP) family--stromelysin, 72-kilodalton (kD) gelatinase, and 92-kD gelatinase--were investigated. When stromal cells are situated in the normal corneal stroma, they produce only a single MMP, 72-kD gelatinase. This pattern of expression was reproduced by stromal cells freshly plated in primary culture. However after passage in culture, the cells also began to secrete collagenase and stromelysin. Treatment of primary cultures with recombinant human IL-1 also induced collagenase and stromelysin expression. In addition, 92-kD gelatinase expression was induced and 72-kD gelatinase expression was increased further by IL-1 treatment. Treatment of passaged cultures or IL-1-treated primary cultures with recombinant human TGF-beta reverted the pattern of enzyme expression toward that exhibited by primary, untreated cultures, ie, expression of collagenase and stromelysin was repressed while expression of 72-kD gelatinase was increased. These results suggest that TGF-beta and IL-1 may be important agents for controlling MMP expression in healthy and diseased corneas.

Animals↗