Profiles of matrix metalloproteinase activity in equine tear fluid during corneal healing in 10 horses with ulcerative keratitis

OBJECTIVE

Levels of tear film matrix metalloproteinases (MMPs) activity are significantly elevated in horses with ulcerative keratitis and contribute to the excessive breakdown of stromal collagen. Changes in the amount of proteolytic activity in horse tear film during corneal healing and stromal remodeling have not yet been reported, but we hypothesize they should decrease. In the present study we analyzed serial tear fluid from horses with ulcerative keratitis to identify any changes in MMP activity during corneal healing and stromal remodeling.

PROCEDURES

Samples of tear fluid were obtained from both eyes of 10 horses with ulcerative keratitis on the day of admission (day 1) at the hospital and then at various time points until complete healing of the cornea. Tear film MMP2 and MMP9 activity was determined by quantitative gelatin zymography. In all cases medical treatment included topical applications of equine serum, antibiotics, atropine and systemic administration of anti-inflammatory drugs. Surgical procedures were performed in several cases on day 2 in addition to the medical treatment.

RESULTS

The mean total MMP activity (+/- SD) measured in relative standard units (RSU) in the tear fluid of the ulcerated eye (2.44 +/- 1.44) of the 10 horses was significantly higher than the mean in the contralateral eye (0.81 +/- 0.68) (P = 0.006), on the day of admission at the VMTH. The mean MMP activity in these ulcerated eyes significantly decreased (-82.4%) between the first day of admission and the day when the ulcer had completely healed (P = 0.0002). The activity level in the healed eye (0.43 +/- 0.17) was not significantly different to the one in the contralateral eye (0.36 +/- 0.18) on the day of complete corneal healing (P = 0.374). The level of MMP activity in the contralateral eye also decreased from 0.81 +/- 0.68-0.36 +/- 0.18 but this decrease (56%) was not significant (P = 0.069).

CONCLUSIONS

Ulcerative keratitis in horses is associated with initially high levels of tear film proteolytic activity that decrease as the ulcers heal. The success of medical and surgical treatment of the corneal ulcers is reflected by the enzyme activity in tears. In horses successful treatment does lead to a rapid reduction in tear film proteolytic activity that corresponded with the improvement in the clinical signs of corneal ulceration. Measurement of MMP activity in the tear film might represent a way to monitor the progression of corneal healing in horses with ulcerative keratitis.

Connective tissue growth factor in tear film of the horse: detection, identification and origin

BACKGROUND

Healing of corneal ulcers in horses is often associated with profound corneal stromal fibrosis and scar formation resulting in visual impairment. Connective tissue growth factor (CTGF) is a fibrogenic cytokine involved in wound healing and scarring. The purpose of this study was to determine whether CTGF was present in the tear fluid of normal horse eyes and the eyes of horses with corneal ulcers in order to evaluate the role of CTGF in corneal wound healing and corneal scar formation.

METHODS

Tear fluid samples were collected from 65 eyes of 44 horses; 32 samples from normal eyes, 21 samples from eyes with corneal ulceration, and 12 samples from the unaffected contralateral eyes of horses with ulcers. CTGF levels in the tears were determined by enzyme immunoassay using goat IgG against human CTGF. Antigenetic similarity of human and horse CTGF was established in a bio-equivalence assay. The identity of horse CTGF was confirmed by western blot. Lacrimal and nictitating membrane glands were investigated by immunohistochemistry in the attempt to clarify the origin of tear fluid CTGF.

RESULTS

CTGF was detected in tear film of 23 normal unaffected eyes (72%) and 8 normal contralateral eyes (67%), with the mean CTGF levels (+/- SEM) being 51.5+/-19.2 and 13.4+/-3.9 ng/ml respectively. CTGF was found in 8 eyes with corneal ulcers (38%) with the mean CTGF concentration of 26.3+/-14.8 ng/ml. Western blot identified the protein detected as CTGF. The identification of CTGF in lacrimal glands suggests a major role of these glands in the presence of CTGF in tears.

CONCLUSIONS

CTGF is present in horse tear fluid and derives, at least partly, from the lacrimal gland. Equine CTGF has strong antigenic similarity with human CTGF. Corneal disease leads to a decrease of CTGF concentrations in tears. The possible role of CTGF in the healing process of ocular surface requires further investigation.

Novel antisense oligonucleotides targeting TGF-beta inhibit in vivo scarring and improve surgical outcome

The scarring response is an important factor in many diseases throughout the body. In addition, it is a major problem in influencing results of surgery. In the eye, for example, post-operative scarring can determine the outcome of surgery. This is particularly the case in the blinding disease glaucoma, where several anti-scarring regimens are currently used to improve glaucoma surgery results, but are of limited use clinically because of severe complications. We have recently identified transforming growth factor-beta (TGF-beta) as a target for post-operative anti-scarring therapy in glaucoma, and now report the first study of novel second-generation antisense phosphorothioate oligonucleotides against TGF-beta in vivo. Single applications of a TGF-beta OGN at the time of surgery in two different animal models closely related to the surgical procedure performed in glaucoma patients, significantly reduced post-operative scarring (P<0.05) and improved surgical outcome. Our findings suggest that TGF-beta antisense oligonucleotides have potential as a new therapy for reducing post-surgical scarring. Its long-lasting effects after only a single administration at the time of surgery make it particularly attractive clinically. Furthermore, although we have shown this agent to be useful in the eye, it could have widespread applications anywhere in the body where the wound-healing response requires modulation.

Effect of healing on the expression of transforming growth factor beta(s) and their receptors in chronic venous leg ulcers

The transforming growth factor betas are of major importance in the wound repair process; however, no studies to date have investigated the role of the transforming growth factor beta receptors in chronic venous leg ulcers or what effect healing has on these proteins. To determine whether the transforming growth factor beta peptides and their receptors are expressed in chronic venous wounds, we used immunofluorescent analysis and quantitative competitive reverse transcription polymerase chain reaction to identify the protein and mRNA expression, respectively. Biopsy samples from wounds and normal skin were collected from 12 patients with chronic venous leg ulcers and three patients undergoing reconstructive surgery, respectively. Additionally four of the chronic venous leg ulcer patients were re-biopsied between 2 and 8 wk after the first biopsy when the wounds had entered the healing phase. The tissue excised from the ulcers included the surrounding intact skin, the ulcer edge, and the ulcer base. Immunofluorescent staining for transforming growth factors beta1, beta2, and beta3 was observed within the epidermis of the skin surrounding the chronic venous ulcers and in fibroblasts and inflammatory cells of the dermis, although this staining was not as strong as that seen in normal unwounded skin. Very little staining could be seen within the ulcers for any of the ligands, however. In contrast the transforming growth factor beta type I receptor was observed throughout the ulcers and the normal unwounded skin biopsies, particularly in the basal epidermal cells. No immunofluorescence for the type II transforming growth factor beta receptor was observed in any of the ulcer biopsies investigated, although it was observed throughout the epidermis and in fibroblasts and inflammatory cells in the surrounding skin. Quantitative, competitive reverse transcription polymerase chain reaction was used to analyze mRNA expression for transforming growth factor beta1 and the type II receptor in the nonhealing ulcers and normal unwounded skin biopsies. These studies revealed that transforming growth factor beta1 and transforming growth factor beta receptor II mRNA was expressed in all the chronic nonhealing ulcers albeit at very low levels for the type II receptor. In marked contrast to the staining observed in nonhealing chronic ulcers, positive immunostaining was observed for the transforming growth factor betas and both the type I and type II receptors in healing ulcers. These results suggest that the absence of a viable receptor complex for the transforming growth factor betas in nonhealing chronic venous ulcers may contribute to wound chronicity.

Pterygia pathogenesis: corneal invasion by matrix metalloproteinase expressing altered limbal epithelial basal cells

OBJECTIVE

To assess the potential role of matrix metalloproteinases (MMPs) in the pathogenesis of pterygia by comparing the immunolocalization patterns of MMPs in altered limbal basal stem cells, activated fibroblasts, and areas of elastotic degeneration adjacent to the pterygia.

METHODS

Nine primary and 1 recurrent pterygia along with normal superior limbal-conjunctival tissue and cornea were immunostained with mouse monoclonal antibodies specific for MMP-1, MMP-2, MMP-3, MMP-9, membrane type 1 (MT1)-MMP (MMP-14), and membrane type 2-MMP (MMP-15).

RESULTS

Normal conjunctival, limbal, and corneal cells lacked significant immunostaining except for cell surface MT1-MMP. In contrast, altered limbal basal epithelial cells of the 9 primary and 1 recurrent pterygia immunostained for all 6 MMPs. Activated and altered fibroblasts associated with the pterygia immunostained primarily for MMP-1. In contrast, stromal areas of elastotic degeneration (pingueculae) showed variable immunostaining of MMPs.

CONCLUSIONS

Altered limbal basal epithelial cells (pterygium cells) immunostained for multiple types of MMPs in contrast to normal conjunctival, limbal, and corneal cells. The pterygium cells invading over Bowman's layer produce elevated MMP-1, MMP-2, and MMP-9 expression, which probably are the main MMPs responsible for the dissolution of Bowman's layer. Pterygium cells may also cause activation of fibroblasts at the head of the pterygium, leading to the initial cleavage of fibrillar collagen in Bowman's layer by the production of MMP-1. Altered fibroblasts in areas of elastotic degeneration (pingueculae) trailing behind the pterygium constitute a second type of tumor, which is noninvasive.

CLINICAL RELEVANCE

These data of altered MMP expression support the concept that altered basal limbal epithelial cells play a key role in the formation and migration of a pterygium.

Causes and effects of the chronic inflammation in venous leg ulcers

The pathogenesis of venous leg ulcers is multifactorial. In this review article new physiological, molecular and cellular abnormalities in venous ulcers related to the chronic inflammation are presented and discussed. Venous hypertension causes disturbed microcirculation and pathological changes of the capillaries, which eventually locks the condition in a self-amplifying, detrimental cascade with persistent elevated levels and activities of pro-inflammatory cytokines and proteases preventing progress into a healing phase. As a consequence fibroblasts senescence and become less responsive to growth factors the older the ulcers become. Current data imply there is no deficiency but rather an unfavorable distribution of growth factors in venous ulcers. An imbalance in proteolytic enzymes and their endogenous inhibitors is a common finding in chronic venous leg ulcers. Variation in disease severity and concomitant ailments in this heterogeneous patient group may explain the contradictory results in the literature. Thus, to advance the areas of research further, longitudinal studies involving larger number of patients are required to identify the major pathogenic factors.

Amniotic fluid concentrations of matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 during pregnancy and labor

OBJECTIVE

This study was undertaken to determine whether obstetric factors affect the concentrations of matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 in the amniotic fluid.

STUDY DESIGN

We prospectively collected amniotic fluid samples from 109 women at various stages of pregnancy and labor and determined matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 concentrations by means of enzyme-linked immunosorbent sandwich assay systems. With multiple regression analysis we evaluated relationships between amniotic fluid matrix metalloproteinase 9 concentration and tissue inhibitor of metalloproteinase 1 concentration and the following factors: gestational age, presence of labor, cervical dilatation, membrane status, presence of clinical chorioamnionitis, and microbial colonization of the amniotic fluid.

RESULTS

The detectable presence of amniotic fluid matrix metalloproteinase 9 was independently associated with intra-amniotic infection, labor, cervical dilatation, and spontaneous rupture of membranes. Chorioamnionitis and amniotic fluid matrix metalloproteinase 9 concentrations were correlated with tissue inhibitor of metalloproteinase 1 levels.

CONCLUSIONS

Intra-amniotic infection, advanced labor, and rupture of membranes before the onset of labor were independently associated with the presence of matrix metalloproteinase 9 in the amniotic fluid. Both pathologic and physiologic processes appear to produce shifts in the balance between degradation and synthesis of the extracellular matrix.

Enhanced short-term plasmid transfection of filtration surgery tissues

PURPOSE

To quantify and localize plasmid transfection of filtration surgery tissues using two delivery techniques.

METHODS

Full-thickness filtering procedures were performed on eyes of New Zealand albino rabbits. In 10 eyes, naked plasmid DNA in saline was either injected beneath Tenon's capsule at the filtration site or absorbed into a collagen shield that was then placed external to the sclerostomy and under the Tenon's capsule. Forty-eight hours after surgery, levels of the reporter gene, chloramphenicol acetyltransferase (CAT) were measured in samples of ocular tissues. In two additional eyes, the ss-galactosidase (ss-GAL:) reporter gene expression was localized histologically.

RESULTS

Injection of plasmid DNA in saline vehicle into the filtration bleb produced readily detectable CAT activity in bleb tissue (conjunctiva, Tenon's capsule, and sclera) whereas CAT activity was nearly undetectable in samples of the cornea, iris-ciliary body, and tissues located opposite the bleb site. Delivery of the plasmid DNA into the bleb through a collagen shield increased CAT activity 30-fold over injection of plasmid in saline (2711 +/- 567 mU/mg versus 92 +/- 38 mU/mg). ss-Gal activity was imaged only in the region of the bleb, and microscopic examination showed ss-Gal activity localized to Tenon's capsule fibroblasts, with minimal ss-Gal activity observed in inflammatory cells or scleral fibroblasts.

CONCLUSIONS

Transfection of filtration tissues is enhanced by absorption of naked DNA into a collagen shield. Furthermore, transfection is localized to the fibroblasts and inflammatory cells of the filtration bleb site. Gene therapy using naked plasmid DNA and a simple collagen shield delivery vehicle may be useful for regulating wound healing after glaucoma surgery.

TGF-beta1, -beta2, and -beta3 in vitro: biphasic effects on Tenon's fibroblast contraction, proliferation, and migration

PURPOSE

To compare the effects of the three human transforming growth factor-beta (TGF-beta) isoforms and different concentrations of TGF-beta on human Tenon's capsule fibroblasts (HTF), with a view to delineating the role of this growth factor in the subconjunctival scarring response after glaucoma filtration surgery.

METHODS

Application of recombinant human TGF-beta1, -beta2, and -beta3 (range 0-10(-8) M) was assessed using several assays of HTF function: fibroblast-mediated collagen contraction, proliferation, and migration.

RESULTS

All three isoforms of TGF-beta behaved in a similar manner in vitro. They each stimulated HTF-mediated collagen contraction, proliferation, and migration with a characteristic concentration-dependent response, with peak activities at 10(-9), 10(-12), and 10(-9) M, respectively, that were significantly different from control (P<0.05). At concentrations above and below peak activities, HTF activity was reduced, demonstrating biphasic effects of TGF-beta.

CONCLUSIONS

TGF-beta1, -beta2, and -beta3 have similar actions in vitro; this is demonstrated by their effects on several HTF-mediated functions. TGF-beta induces a response in HTF that is concentration-dependent, with different functions being maximally stimulated at different concentrations. This biphasic response highlights the significance of the concentration profile of TGF-beta at the wound site. These findings are important in filtration surgery, where constant changes in the local environment occur due to the passage of aqueous and the wound healing process. The varying levels of TGF-beta in the aqueous and subconjunctival tissues may thus significantly modify the conjunctival scarring response.

Transforming and epidermal growth factors in degenerated intervertebral discs

We studied the presence of anabolic growth factors in human herniated intervertebral discs (IVD) using a reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry. Messenger RNA (mRNA) was isolated from the nucleus pulposus using oligo (dT)25 superparamagnetic beads and probing with gene-specific primers in RT-PCR. mRNA coding for TGF-alpha (3/10), EGF (0/10), TGF-beta1 (0/10) and TGF-beta3 (2/10) or the EGF receptor (EGF-R; 0/10) and TGF-beta type-II receptor (0/10) was found only occasionally. Beta-actin was always present and positive sample controls confirmed the validity of the RT-PCR assay. These RT-PCR findings were confirmed using immunohistochemical staining of EGF and TFG-beta, whereas TGF-alpha protein was always found associated with discocytes. We conclude that the nucleus pulposus of the herniated IVD is vulnerable to proteolytic degradation and depletion of proteoglycans due to the lack and/or low production of anabolic growth factors/receptors which could increase the local synthesis of the extracellular matrix.

Molecular and mechanistic validation of delayed healing rat wounds as a model for human chronic wounds

The purpose of this study was to provide molecular and mechanistic evaluation of an ischemic wound model in rats to determine if it is a valid model for human chronic wounds. Compared to acute wounds, human chronic wounds contain markedly elevated levels of proinflammatory cytokines and matrix metalloproteinases, while matrix metalloproteinase inhibitors and growth factor activity are diminished. Accordingly, tissue from ischemic and normal rat wounds were analyzed for cytokine, proteases and growth factor levels. Dorsal full thickness punch wounds were created in rats using a reproducible template. The ischemic wound group (n = 10) had six uniformly placed wounds within a bipedicled dorsal flap. The control group (n = 10) had the same wounds created without elevation of a flap. On postwound days 3, 6 and 13 wounds were excised and analyzed. Protein levels for tumor necrosis factor-alpha were determined with a rat-specific enzyme-linked immunosorbent assay, while mRNA was determined by RNase protection assay. Matrix metalloproteinases and serine protease detection was done using gelatin and casein zymography, respectively. Significant delay in healing was achieved in the ischemic group: 50% healing for control wounds was at 7 days and 11 days for ischemic wounds (p < 0.001). No significant differences between wound groups were found for interleukin-1beta, and mRNA for tumor necrosis factor-alpha and interleukin-1beta. However, at day 13 ischemic wounds contained significantly more tumor necrosis factor-alpha than controls and normal skin (586 +/- 106 pg/biopsy vs. 79 +/- 7 pg/biopsy vs. 52 +/- 2 pg/biopsy; p < 0. 001). Zymography showed substantially greater quantities of matrix metalloproteinase-2, matrix metalloproteinase-9, and serine proteases in ischemic wounds. This model of delayed healing in rats shares many of the key biochemical, molecular and mechanistic characteristics found in human chronic wounds, namely elevated tumor necrosis factor-alpha and protease levels. As such, this model will likely prove to be useful in chronic wound research, particularly in developing novel therapeutics.

Amniotic fluid matrix metalloproteinase-9 levels in women with preterm labor and suspected intra-amniotic infection

OBJECTIVE

To determine the accuracy of amniotic fluid (AF) matrix metalloproteinase-9 measurements for diagnosing intra-amniotic infection in women with preterm labor.

METHODS

We performed amniocenteses in 44 women between 22 and 35 weeks' gestation who presented to our center with preterm labor and clinical suspicion of intra-amniotic infection. Each sample was analyzed by glucose measurement, Gram stain, and culture for aerobes, anaerobes, and mycoplasmas. We tested the AF for matrix metalloproteinase-9 using gelatin zymography and a commercial enzyme-linked immunosorbent assay (ELISA) system. We calculated accuracy and confidence intervals (CIs) for AF matrix metalloproteinase-9, glucose, and Gram stain for diagnosing intra-amniotic infection, using culture as the criterion standard.

RESULTS

All patients who had matrix metalloproteinase-9 detectable by ELISA also demonstrated matrix metalloproteinase-9 by zymography. Six cases of intra-amniotic infection were confirmed by culture (prevalence 14%). The performance statistics of AF matrix metalloproteinase-9 for diagnosing intra-amniotic infection were: sensitivity 83% (95% CI 53, 99), specificity 95% (95% CI 88, 99), positive predictive value 71% (95% CI 37, 99), and negative predictive value 97% (95% CI 92, 99). Two women had false-positive results; one had gram-negative rods on the AF Gram stain and developed clinical signs and symptoms of chorioamnionitis several hours after amniocentesis and the other had a purulent vaginal discharge and an AF glucose level less than 15 mg/dL. Both delivered within 24 hours of amniocentesis.

CONCLUSION

Measuring matrix metalloproteinase-9 in the AF appeared to be reliable for diagnosing intra-amniotic infection. An elevated matrix metalloproteinase-9 concentration in the AF at a preterm gestational age may portend imminent delivery regardless of microbiologic confirmation of intra-amniotic infection.

Keratinocyte collagenase-1 expression requires an epidermal growth factor receptor autocrine mechanism

In response to cutaneous injury, expression of collagenase-1 is induced in keratinocytes via alpha2beta1 contact with native type I collagen, and enzyme activity is essential for cell migration over this substratum. However, the cellular mechanism(s) mediating integrin signaling remain poorly understood. We demonstrate here that treatment of keratinocytes cultured on type I collagen with epidermal growth factor receptor (EGFR) blocking antibodies or a specific receptor antagonist inhibited cell migration across type I collagen and the matrix-directed stimulation of collagenase-1 production. Additionally, stimulation of collagenase-1 expression by hepatocyte growth factor, transforming growth factor-beta1, and interferon-gamma was blocked by EGFR inhibitors, suggesting a required EGFR autocrine signaling step for enzyme expression. Collagenase-1 mRNA was not detectable in keratinocytes isolated immediately from normal skin, but increased progressively following 2 h of contact with collagen. In contrast, EGFR mRNA was expressed at high steady-state levels in keratinocytes isolated immediately from intact skin but was absent following 2 h cell contact with collagen, suggesting down-regulation following receptor activation. Indeed, tyrosine phosphorylation of the EGFR was evident as early as 10 min following cell contact with collagen. Treatment of keratinocytes cultured on collagen with EGFR antagonist or heparin-binding (HB)-EGF neutralizing antibodies dramatically inhibited the sustained expression (6-24 h) of collagenase-1 mRNA, whereas initial induction by collagen alone (2 h) was unaffected. Finally, expression of collagenase-1 in ex vivo wounded skin and re-epithelialization of partial thickness porcine burn wounds was blocked following treatment with EGFR inhibitors. These results demonstrate that keratinocyte contact with type I collagen is sufficient to induce collagenase-1 expression, whereas sustained enzyme production requires autocrine EGFR activation by HB-EGF as an obligatory intermediate step, thereby maintaining collagenase-1-dependent migration during the re-epithelialization of epidermal wounds.

Analysis of protease activity in human otitis media

Chronic otitis media is a common problem associated with a nonintact tympanic membrane frequently involving Staphylococcus aureus and Pseudomonas aeruginosa. The virulence of Pseudomonas bacteria is related to the production of two matrix metalloproteinases, elastase and alkaline protease. Serine proteases, such as neutrophil elastase, are produced by the host inflammatory response. These proteases are thought to contribute to tissue destruction and assist bacterial invasion during infection. This preliminary study was done to identify protease activity in otorrhea samples from patients with otitis media and a nonintact tympanic membrane and to examine the ability of selective protease inhibitors to decrease protease activity. Ilomostat (galardin) is a synthetic, specific inhibitor of matrix metalloproteinases including P. aeruginosa elastase and alkaline protease, whereas alpha1-antitrypsin inhibits serine proteases including neutrophil elastase. Samples were collected and cultured from 20 patients with otorrhea resulting from tympanic membrane perforations or pressure-equalization tubes. A protease assay that used azocasein as the substrate was used to quantify protease activity, with and without addition of selective protease inhibitors. Cultures revealed P. aeruginosa alone in 7 samples, P. aeruginosa plus other organisms in 10, and S. aureus alone in 3. Protease activity was detected in 15 (75%) of the samples. A statistically significant (p < 0.05) decrease in protease activity was seen with the addition of alpha1-antitrypsin or Ilomostat plus alpha1-antitrypsin, but not with Ilomostat alone. Analyzing the 10 samples with the highest protease activity, a statistically significant decrease in activity was seen with Ilomostat or alpha1-antitrypsin alone and with both Ilomostat and alpha1-antitrypsin together. Bacteriologic type, source of sample, age and gender of the subject, and duration of infection were not significantly related to protease activity. This is the first study to quantify protease activity and inhibition by selective protease inhibitors in human otorrhea. Protease inhibitors effectively decrease protease activity in most cases and in addition to standard antibiotic therapy might prove beneficial in the treatment of otitis media with a nonintact tympanic membrane. This study supports future clinical investigations into the role of proteases and inhibition of protease activity in the treatment of otitis media.

Messenger RNA levels for genes involved in extracellular matrix from human corneal scrapings before and after photorefractive keratectomy

PURPOSE

To measure the levels of mRNA for genes important in cellular and extracellular matrix regulation in human corneal epithelium before and after photorefractive keratectomy (PRK) in order to explain myopic regression following surgery.

METHODS

Scrapings from 26 normal corneas before a first photorefractive keratectomy were randomly pooled in two samples of 16 and 10 scraping, respectively, and compared to another 23 scrapings from corneas with myopic regression after a previous photorefractive keratectomy, also randomly pooled in another 2 samples of 16 and 7 scrapings each. The scrapings were analysed for seven different messenger RNAs involved in extracellular matrix using competition-based quantitative reverse-transcription polymerase chain reaction.

RESULTS

Messenger RNAs for TGFalpha (Transforming growth factor-alpha), TGFbeta1 (Transforming growth factor-beta1), EGF-R (Epidermal growth factor-receptor) and TIMP1 (Tissue inhibitor metalloproteinase-1) were present in all samples. No mRNA for MMP9 (Metalloproteinase 9) or MMP2 (Metalloproteinase 2) were detected in any sample. Messenger RNA for collagen (alpha1) III was present in one sample following photorefractive keratectomy.

CONCLUSIONS

The detection and measurement of levels of messenger RNA for selected growth factors, receptors, metalloproteinases and extracellular matrix proteins in ex vivo samples of human corneal epithelium is important and possible with a modified polymerase chain reaction technique. Messenger RNAs for Collagen III and for TGF-beta1 were elevated in one sample after photorefractive keratectomy.

Changes in the expression of extracellular matrix (ECM) and matrix metalloproteinases (MMP) of proliferating rat parotid acinar cells

Tissue morphogenesis, development, and maintenance of function are mediated by signals generated through the composition of the extracellular matrix. The regulation of the composition of matrix is determined by enzymes specific for their degradation, the matrix metalloproteinases. Chronic injections of the beta-adrenergic receptor agonist, isoproterenol, result in a non-neoplastic hypertrophy and hyperplasia of the rat parotid gland. The activity of matrix metalloproteinases, as measured by gelatin zymography and enzymatic digestion of Azocoll substrates by gland lysates, decreased significantly (P < 0.05) following 24 hrs of agonist treatment, and slowly recovered to control values by 6 days of treatment. Daily administration of the broad-spectrum matrix metalloproteinase inhibitor Galardin for 3 days in combination with isoproterenol resulted in enhanced gland hypertrophy compared with that produced by isoproterenol alone. Given alone, Galardin also caused hypertrophy. The relative abundance of mRNA for the extracellular matrix molecules, collagens I and III and fibronectin, declined rapidly following the initiation of beta-agonist treatment in vivo, while laminin B1 and B2 mRNA levels increased initially before declining below control levels. These changes in patterns of mRNA levels also were observed in the concentrations of glandular protein when Western dot blot analysis of collagens I and III and laminin, respectively, was used. The importance of laminin, in vivo, was demonstrated by coinjection of anti-laminin antibody along with isoproterenol, which resulted in the inhibition of beta-agonist-induced parotid gland hypertrophy and hyperplasia. These data suggest that modulation of the ECM is associated with isoproterenol-induced salivary gland hypertrophy and hyperplasia. It is likely that this modulation of the ECM takes place through transcriptional regulation of some ECM genes and regulation of matrix-degrading enzyme activity.

Inhibition of transforming growth factor alpha stimulation of human squamous cell carcinoma of the head and neck with anti-TGF-alpha antibodies and tyrphostin

BACKGROUND

Transforming growth factor alpha (TGF-alpha) and its receptor (EGF-R) may regulate normal and malignant epithelial cell growth by an autocrine mechanism. We investigated the role of TGF-alpha in regulating head and neck SCC tumor growth.

METHODS

TGF-alpha and EGF-R levels were measured in 7 SCC cell lines and 14 SCC biopsies by RIA, Scatchard, and Western analysis. TGF-alpha autocrine stimulation of DNA synthesis in SCC cell lines was assessed by incubation with TGF-alpha neutralizing antibodies and tyrphostin AG 1478, a selective and potent inhibitor of EGF-R kinase.

RESULTS

All SCC cell lines synthesized TGF-alpha and expressed elevated EGF-R levels compared to normal keratinocytes. Twelve of the 14 SCC biopsies contained TGF-alpha protein and 8 had specific EGF-R. Exogenous TGF-alpha or EGF significantly increased DNA synthesis in 4 of 5 SCC cell lines. TGF-alpha neutralizing antibodies or tyrphostin AG 1478 reduced DNA synthesis in the two SCC cell lines (FaDu and SCC9) tested.

CONCLUSIONS

These results indicate that SCC cell lines and tumors usually synthesize TGF-alpha, have elevated levels of EGF-R, and are mitogenically stimulated by a TGF-alpha autocrine system. Selective inhibition of the TGF-alpha system by EGF-R kinase inhibitors or TGF-alpha neutralizing antibodies may be useful strategies for treating SCC that overexpress TGF-alpha and its receptor.

Age-related differences in the temporal and spatial regulation of matrix metalloproteinases (MMPs) in normal skin and acute cutaneous wounds of healthy humans

Despite the association of increasing age with chronic wound-healing disorders and an impaired rate of healing of acute cutaneous wounds, the role of matrix metalloproteinases (MMPs) is unknown. To determine the spatial and temporal patterns and activities of MMP-1, -2, -3 and -9, 132 healthy humans aged between 19 and 96 years underwent 4-mm punch biopsies followed by wound excision between day 1 and day 180 post-wounding. Wounds showed an age-related increase in MMP-2 and MMP-9 immunostaining from day 3; this was associated with degradation of gelatin as shown by zymograms and with increased proteinase activity as shown by azocoll assays. Distinct spatial localisations for each MMP were observed: MMP-2 was found in epidermal structures; MMP-9 was observed in inflammatory cells up to day 21; MMP-1 was localised to keratinocytes at the wound margin. Normal old skin showed pro-MMP-2 bands on zymography and increased MMP-2 immunostaining. These results indicate that: (1) intrinsic ageing is associated with the up-regulation of MMPs previously associated with chronic wound healing; (2) wound-tissue proteinases are essentially active up to day 21 postwounding; and (3) intrinsic ageing may predispose to tissue breakdown disorders because of MMP-2 up-regulation in normal skin.

Estrogen accelerates cutaneous wound healing associated with an increase in TGF-beta1 levels

The cellular and molecular mechanisms underlying the effects of aging on human cutaneous wound healing are poorly understood, and the possible role of reproductive hormones in this process has never been investigated. We report that aging in healthy females was associated with a reduced rate of cutaneous wound healing, but an improved quality of scarring both microscopically and macroscopically, and with reduced levels of transforming growth factor-beta1 (TGF-beta1) immunostaining and steady-state mRNA in the wound. These age-related changes were reversed by the systemic administration of hormone replacement therapy (HRT). Moreover, ovariectomized young female rodents exhibited a marked delay in repair of acute incisional wounds, which was reversed by the topical application of estrogen. The cellular mechanism underlying these changes appears to involve an estrogen-induced increase in latent TGF-beta1 secretion by dermal fibroblasts. These results suggest that both the rate and quality of wound healing depend on reproductive hormone levels.

Differential expression of matrix metalloproteinases and their tissue inhibitors in leiomyomata: a mechanism for gonadotrophin releasing hormone agonist-induced tumour regression

Tissue remodelling involving extracellular matrix (ECM) turnover plays a major role in leiomyoma growth and regression, regulated by the combined action of matrix metalloproteinases (MMPs) and the tissue inhibitors of MMPs (TIMPs). We postulated that leiomyomata express MMP and TIMP mRNA and protein, and their expression is inversely regulated during tumour growth and gonadotrophin releasing hormone agonist (GnRHa)-induced regression. We therefore examined the expression of mRNA and protein for MMPs (interstitial collagenase, MMP-1; gelatinases, MMP-2 and MMP-9; and stromelysin, MMP-3) and TIMPs (TIMP-1 and TIMP-2) in leiomyoma and matched unaffected myometrium from GnRHa (lupron)-treated and untreated patients. Reverse transcription-polymerase chain reaction (RT-PCR) and restriction enzyme analysis revealed that leiomyomata and myometrium expressed MMP-1, -2, -3 and -9, as well as TIMP-1 and -2 mRNA. Quantitative RT-PCR indicated that leiomyomata and myometrium during the secretory phase of the menstrual cycle expressed higher levels of MMP and TIMP mRNA compared to the proliferative phase (P < 0.05), with low to undetectable levels of MMP-1, -2 and -3 mRNA in the tumours. GnRHa therapy induced an overall reduction in MMP and TIMP mRNA expression in both leiomyomata and myometrium, but a significant decrease in TIMP-1, and an increase in MMP mRNA expression compared with untreated tumours (P < 0.05). Immunohistochemically, MMP-1, -2, -3 and -9 and TIMP-1 and -2 proteins were localized in leiomyomata and myometrial smooth muscle cells, arteriole wall and connective tissue fibroblasts, with an overall increase in MMP and a decrease in TIMP staining intensity in GnRHa-treated groups. The results suggest that MMP and TIMP expression in leiomyoma and myometrium are hormonally regulated, and that GnRHa-induced tumour regression is accompanied by an increase in MMP expression with a concomitant decrease in TIMP-1 expression, which may potentially provide an environment favouring ECM degradation.

Human ageing impairs injury-induced in vivo expression of tissue inhibitor of matrix metalloproteinases (TIMP)-1 and -2 proteins and mRNA

Proteolysis is an essential component of wound healing but, if uncontrolled, it may lead to degradation of the neo-matrix and a delay in wound repair. Despite numerous reports of impaired wound healing associated with increasing age, the control of proteolysis is completely unknown. Tissue inhibitor of matrix metalloproteinases (TIMP)-1 and -2 inhibit the activity of matrix metalloproteinases and the pattern of regulation of these molecules determines in part the spatial and temporal regulation of proteolytic activity. This study reports on TIMP-1 and -2 protein localization using immunocytochemistry in healing wounds of healthy subjects of different ages from day 1 to 6 months post-wounding, and has quantified the mRNA levels for both inhibitors using reverse transcriptase-polymerase chain reaction (RT-PCR). TIMP-1 and TIMP-2 proteins are up-regulated from 24 h post-wounding, with a decrease in staining intensity by day 7 for TIMP-2 and by day 14 for TIMP-1. Steady-state mRNA levels for both TIMPs were significantly greater in normal young skin than in aged skin. In the young, there was a significant increase in mRNA expression for TIMP-1 and -2 by day 3 post-wounding, which decreased by day 14 and had returned to basal levels at day 21. In the wounds of the aged subjects, basal levels were observed for TIMP-1 and -2 at all time-points. These results suggest that intrinsic cutaneous ageing is associated with reduced levels of TIMP mRNA both in normal skin and during acute wound repair. These levels may be instrumental in dermal tissue breakdown in normal skin, retarded wound healing, and the predisposition of the elderly to chronic wound healing states.

Alpha-smooth muscle actin expression in rat and mouse mesenteric wounds after transforming growth factor-beta1 treatment

Rat mesenteric perforations heal by contraction within 5 to 7 days, whereas mouse mesenteric perforations seldom close within 3 weeks unless stimulated by transforming growth factor-beta1. In this article, we quantified the expression of alpha-smooth muscle actin by quantitative-reverse transcription-polymerase chain reaction and the orientation of actin filaments at the wound margin by Fourier transformation image analysis after treatment with transforming growth factor-beta1. The expression of transforming growth factor-beta1 and its type II receptor was also assessed. Actin filaments were shown to increase with time at the wound margin in both species and the expression of alpha-smooth muscle actin mRNA increased simultaneously. Transforming growth factor-beta1 enhanced the alpha-smooth muscle actin expression four to five times in rats and three to four times in mice on day 5, but the number of copies expressed per cell was 15-fold higher in rats than in mice. Transforming growth factor-beta1 was down-regulated after wounding in free peritoneal cells of rats, but maintained until day 5 in transforming growth factor-beta1-treated mice. The main finding of this study was that untreated, normal rats expressed substantially more alpha-smooth muscle actin than mice. After treatment with transforming growth factor-beta1, this expression increased similarly in both species. It can be hypothesized that normal closure of mesenteric perforations requires a minimum level of actin expression. This level is not reached in normal mice, but is exceeded after stimulation. Perforations in the rat always close, because the alpha-smooth muscle actin expression is always above this level.

Expression of alpha-smooth muscle actin, TGF-beta 1 and TGF-beta type II receptor during connective tissue contraction

Closure of rat mesenteric perforation is considered to occur by connective tissue contraction, a process that has been shown to be stimulated by transforming growth factor-beta 1. In the present study, we assessed the expression of alpha-smooth muscle actin during closure by quantitative-reverse transcription-polymerase chain reaction and in situ hybridization. The expression of transforming growth factor-beta 1 and transforming growth factor-beta type II receptor was also estimated in mesenteric membranes and free peritoneal cells after wounding. A larger expression of alpha-smooth muscle actin was seen around the wound edges compared to unwounded tissue. Both alpha-smooth muscle actin and transforming growth factor-beta type II receptor were expressed during Days 0, 3, 5, 7, and 10. The expression of alpha-smooth muscle actin on Day 5 was > 100 times higher than on Day 0. Transforming growth factor-beta 1 was expressed in both membranes and free peritoneal cells of unoperated control animals but down-regulated after wounding, a finding that has not been reported previously. It reappeared on Days 7 and 10 in free peritoneal cells but not in perforated membranes. The enhanced expression of alpha-smooth muscle actin and down-regulation of transforming growth factor-beta 1 expression after wounding appears to be important phenomena in tissue contraction and repair.

Single exposures to antiproliferatives: long-term effects on ocular fibroblast wound-healing behavior

PURPOSE

To determine the long-term effects of single, 5-minute exposures to 5-fluorouracil (5FU) and mitomycin-C (MMC) on Tenon's capsule fibroblast migration, growth factor production, growth factor receptor expression, and extracellular matrix (ECM) production.

METHODS

Monolayer cultures and the overlying growth medium of Tenon's capsule fibroblasts exposed to 5FU (0.25 to 25 mg/ml) or MMC (0.001 to 0.1 mg/ml) were harvested up to 48 days after treatment. The expression of growth factors and growth factor receptors, including transforming growth factor beta (TGFbeta), basic fibroblast growth factor (bFGF), and epidermal growth factor (EGF), and ECM molecules (collagen type I, collagen type III, and fibronectin) were quantitated at the mRNA and protein levels. The ability of fibroblasts exposed to 5FU and MMC to migrate to fetal calf serum was also investigated up to 48 days after treatment.

RESULTS

Control cultures were found to produce the growth factors TGFbeta and bFGF but not EGF. Exposure to 5FU or MMC resulted in an initial significant increase (P < 0.05) in the production of TGFbeta and bFGF, with levels then decreasing toward those of controls. Cells exposed to 5FU or MMC exhibited an initial significant decrease (P < 0.05) in the number of TGFbeta, bFGF, and EGF growth factor receptors, with subsequent recovery toward control levels by day 48 after treatment. Both 5FU and MMC caused a significant reduction (P < 0.05) in collagen type I and fibronectin production compared to controls throughout the 48-day culture period. The production of collagen type III was initially elevated (P < 0.05) compared to controls after exposure to 5FU or MMC, production then decreasing toward control levels over the remainder of the 48-day culture period. The migration of cells exposed to 5FU or MMC was significantly reduced (P < 0.05) compared to controls up to 48 days after treatment; these cells exhibited a partial recovery of migratory ability throughout this period.

CONCLUSIONS

Fibroblasts whose growth was arrested using single, short exposures to 5FU or MMC appear to be capable of performing several crucial aspects of wound healing, including the expression of growth factors and receptors and ECM molecules and the ability to migrate. These findings may help explain why in some patients treated with antiproliferatives, glaucoma filtration surgery fails because of scarring.

Extracellular-matrix gene expression during mouse submandibular gland development

Early morphogenesis of mouse submandibular glands begins on late day 11 of fetal development when the epithelium begins to bud from the surrounding mandibular mesenchyme. Using total RNA collected from fetal BALB/c submandibular glands, steady-state levels of mRNA expression for extracellular matrix molecules were measured using quantitative competitive reverse transcription-polymerase chain reaction (RT-PCR). By comparing the PCR amplification products of both the cellular mRNA and a synthetic template, pMATRIX, it was possible to measure the direct expression of collagens alpha2(I), alpha1(III), alpha1(IV), fibronectin, laminin B2, elastin and lysyl oxidase genes. There was an observed trend for an increasing concentration of collagen alpha2(I), collagen alpha1(III) and lysyl oxidase mRNA molecules per cell on day 16 of development. The relative abundance of elastin mRNA was detectable only on day 16. Fibronectin and laminin B2 were more constitutively present but had their highest copy number per cell on day 16. The presence of extracellular-matrix protein was confirmed by immunohistochemistry using day-16 fetal glands and adult glands. With the construction of the pMATRIX supertemplate and the advent of quantitative, competitive RT-PCR technology, it has been possible to measure small changes in the steady-state concentrations for extracellular-matrix mRNA during salivary gland development.

Stimulation of protracted connective tissue repair in normal mice by transforming growth factor beta 1

The repair and contraction during connective tissue repair of mesenteric perforations is prolonged in mice compared with rats. In the present study the stimulating effect of transforming growth factor beta 1 (TGF-beta 1) on different aspects of such repair of the mouse mesentery was assessed. The number of closed mesenteric perforations were counted on different days after operation and the free peritoneal cells were counted, the mitotic index was assessed, and actin distribution of fibroblasts around the perforation was studied with laser scanning confocal microscopy. TGF-beta 1 significantly increased the speed of closure and seemed to induce more actin in fibroblasts at the wound margin. It did not significantly influence the mitotic index, but fewer free peritoneal cells were obtained in mice treated with TGF-beta 1. We conclude that TGF-beta 1 is a potent stimulator of connective tissue repair and contraction in mice. The different methods of closure in rats and mice implicate different molecular responses in wounds and further studies on the stimulating effect of TGF-beta 1 may indicate basic fibroblastic cellular mechanisms that are active during contraction in connective tissue repair.

Interactions of cytokines, growth factors, and proteases in acute and chronic wounds

A healing wound represents a complex series of interactions between cells, soluble mediators, and extracellular matrix. Within this multifaceted environment, there are multiple regulatory points which control the ordered series of events that lead to normal tissue repair. An alteration in this physiologic network can lead to the development of a chronic wound. This article presents an update on the numerous mediators that exist within the wound environment in both acute normal healing and chronic nonhealing wounds. We also present a hypothesis which may provide a conceptual pathophysiologic mechanism with which to understand all chronic wounds.

Inhibition of proteases in Pseudomonas otitis media in chinchillas

The treatment of chronic suppurative otitis media caused by Pseudomonas aeruginosa remains a challenging problem. The virulence of Pseudomonas is related to its secretion of two matrix metalloproteinases, alkaline protease and elastase. This experiment examines the effects of a synthetic inhibitor of matrix metalloproteinases GM 6001, or N-(2(R)-2(hydroxyamido carbonylmethyl)-4-methylpentanoyl)-L-tryptophane methylamide), in a chinchilla Pseudomonas otitis media model. Thirty chinchillas underwent bilateral subtotal tympanic membrane perforations. Twenty-four chinchillas underwent bilateral middle ear inoculation with P. aeruginosa. Chinchillas were divided into four groups of six animals after the establishment of otitis media. Animals in one group were controls; the other three groups received either gentamicin, GM 6001, or gentamicin plus GM 6001 into the external auditory canal three times daily for 4 weeks. Clearance of Pseudomonas infection occurred in three ears of three animals, all in gentamicin groups, with or without GM 6001. Otorrhea (p = 0.0014) and external canal erythema (p = 0.025) were mild in the two gentamicin groups and moderate in the GM 6001 group when compared with bacterial controls. Animals in the GM 6001 group had the highest survival rate, less severe facial paralysis, and less vestibular toxicity than the gentamicin, gentamicin plus GM 6001, or control groups, although these differences were not statistically significant. This pilot study showed encouraging results for a role of ototopical protease inhibitors in the treatment of Pseudomonas otitis media.

Suppression of transforming growth factor-beta (TGF beta) and TGF beta receptor messenger ribonucleic acid and protein expression in leiomyomata in women receiving gonadotropin-releasing hormone agonist therapy

The expression and cellular distribution of transforming growth factor-1 (TGF beta 1) through TGF beta 3 and TGF beta type I-III receptor messenger ribonucleic acid (mRNA) and protein were analyzed in leiomyomata from patients receiving GnRH agonist (GnRHa; leuprolide acetate) compared to those in untreated controls. Standard reverse transcription-PCR revealed that the unaffected myometrium and leiomyomata from leuprolide-treated and untreated patients express TGF beta 1-3 and TGF beta type I-III receptor mRNA. The myometrial and leiomyomata smooth muscle cells were the primary site of TGF beta 1-3 and TGF beta type I and II receptor mRNA and protein expression, as determined by in situ hybridization and immunohistochemical localization. These observations indicate that leiomyomata express a higher of level of TGF beta and TGF beta receptor mRNA and protein than unaffected myometrium during the secretory phase of the menstrual cycle, and women who received leuprolide acetate therapy had a substantially lower level of expression than untreated controls. Furthermore, competition-based quantitative reverse transcription-PCR using synthetic internal standards revealed that leiomyomata express a significantly higher number (copies per cell) of TGF beta type II receptor mRNA, followed by TGF beta 1, TGF beta type I receptor, TGF beta 2, and TGF beta 3 (P < 0.05). However, there was a significant decrease in the levels (copies per cell) of TGF beta 1, TGF beta 3, and TGF beta type I and type II receptor mRNA expression in leiomyomata from leuprolide-treated compared to untreated patients (P < 0.05). The data provide further evidence that leiomyomata express mRNA and protein for all components of the TGF beta system, and GnRHa therapy results in down-regulation of their expression. More specifically, these data suggest that TGF beta 1 and TGF beta 3 may play a more important role in leiomyomata growth than TGF beta 2, which leads us to propose that lowering TGF beta and receptor expression may have a direct effect on leiomyomata regression.

Biochemical analysis of acute and chronic wound environments

The process of wound healing involves a complex interaction between numerous cell types, extracellular matrix molecules, and soluble mediators including growth factors and cytokines. This complex milieu is under active investigation for the purposes of beginning to understand how this environment regulates tissue repair. Quantitation of growth factors, cytokines, and matrix metalloproteinases within surgical wound fluids may help to elucidate this regulatory network, not only in noncomplicated wound healing but also in pathologic lesions such as chronic ulcers.

Effects of transforming growth factor-beta1 on extracellular matrix gene expression by human fibroblasts from a laryngeal stenotic lesion

Transforming growth factor-beta1 appears to play important roles in normal wound healing by increasing synthesis of extracellular matrix components. However, the role of transforming growth factor-beta1 in the production of excessive scar tissue by fibroblasts from stenotic lesions of the larynx has not been evaluated. We examined the effect of transforming growth factor-beta1 on the steady-state messenger RNA levels of elastin, alpha2(l) procollagen, and lysyl oxidase (the enzyme that cross-links both of these structural proteins) in cell cultures of diploid human fibroblasts established from fetal skin, newborn foreskin, and an adult laryngeal stenotic lesion. Time-course and dose-response experiments demonstrated that treatment with 500 pmol/L transforming growth factor-beta1 for 20 hours induced maximal levels of mRNA for elastin (7- to 59-fold) and alpha2(l) procollagen (1.7- to 2.4-fold) in all three cultures of fibroblasts. Transforming growth factor-beta1 also increased levels of lysyl oxidase mRNA in fibroblasts cultured from newborn foreskin (2.4-fold) and a stenotic lesion (10-fold) but had minimal effects on the fibroblasts cultured from fetal skin (1.1-fold), which constitutively expressed high levels of lysyl oxidase mRNA. Furthermore, the fibroblast culture established from a laryngeal stenotic lesion responded with the highest fold-induction for all three mRNAs. Inhibition of mRNA synthesis by actinomycin D showed that transcription was required for transforming growth factor-beta1 induction of elastin, alpha2(l) procollagen, and lysyl oxidase mRNA in all three cultures of fibroblasts. Inhibition of protein synthesis by cycloheximide showed that translation was required for maximal induction by transforming growth factor-beta1 of elastin mRNA but had no observable effect on alpha2(l) procollagen mRNA in all three cultures of fibroblasts. In addition, translation was required for maximal induction of the lysyl oxidase mRNA by transforming growth factor-beta1 in the fibroblasts cultured from a stenotic lesion but not for fibroblast cultures established from fetal and adult skin. These results show that transforming growth factor-beta1 coordinately increases mRNA levels for the structural extracellular matrix proteins collagen and elastin, as well as for the cross-linking enzyme, lysyl oxidase. These data also support the hypothesis that transforming growth factor-beta1 may contribute to the formation of laryngeal stenotic lesions.

Competitive RNA templates for detection and quantitation of growth factors, cytokines, extracellular matrix components and matrix metalloproteinases by RT-PCR

Detection of low-abundance mRNAs by reverse transcription-polymerase chain reaction (RT-PCR) has become a standard technique to determine gene expression by tissues and cells in culture. The ability to determine relative or absolute copy number of specific mRNAs has been difficult due to inadequate internal standards to control for sample-to-sample variation. The use of a synthetic RNA standard with identical sequences to the PCR primers allows reproducible quantitation between samples and assays. By designing multi-sequence templates, several specific mRNAs can be quantitated using a single template. Addition of multiple templates to a single RT reaction allows the quantitation of a large number of targets from as little as 4 micrograms of total RNA. In this report, we present a series of seven primer/template systems to detect and quantitate 52 specific messages, including 26 growth factors and receptors, 8 extracellular matrix components, 10 matrix-modifying enzymes and their inhibitors and 8 cytokines.

Inhibition of pseudomonal ulceration in rabbit corneas by a synthetic matrix metalloproteinase inhibitor

PURPOSE

To evaluate the effect of the synthetic matrix metalloproteinase inhibitor, Galardin, on proteases produced by Pseudomonas aeruginosa (PA) and on a rabbit model of Pseudomonas keratitis.

METHODS

Protease activities of culture broths from Pseudomonas strains PA-28 and W-186 were characterized in vitro by gelatin zymography and by digestion of Azocasein in the presence and absence of Galardin and the serine protease inhibitor, aprotinin. In a noninfectious in vivo experiment, sterile PA culture broth from W-186 was injected intrastromally into rabbit corneas that were treated topically with Galardin or vehicle, then evaluated clinically and histologically. In an infectious in vivo experiment, rabbit corneas were injected with washed PA-28, then treated topically with Galardin or vehicle and clinically scored.

RESULTS

Gelatin zymography of culture broth from W-186 and PA-28 detected two proteases that were both inhibited by Galardin. Galardin reduced the digestion of Azocasein by both PA culture broths by 99%, whereas aprotinin did not significantly reduce the protease activity of PA-28 conditioned broth. Intrastromal injection of sterile W-186 culture broth caused rapid corneal destruction that was prevented by topical treatment with Galardin. Intrastromal injection of washed PA-28 bacteria resulted in progressive corneal melting that was significantly (P < 0.005) delayed, but ultimately not prevented, by topical treatment with Galardin.

CONCLUSIONS

Pseudomonal protease activity in culture broth consisted predominantly of metalloproteinases and were effectively inhibited by Galardin in vitro. Topical treatment with Galardin prevented destruction of rabbit corneas by bacterial products present in culture broth, and it delayed corneal destruction after injection of PA bacteria. Galardin may be a useful adjuvant when corneal destruction proceeds despite prompt antibiotic treatment.

Absorption of epidermal growth factor occurs through the gastrointestinal tract and oral cavity in adult rats

Introduction of radiolabeled epidermal growth factor (125I-EGF) by gavage or sublingual confinement resulted in a time-dependent uptake and systemic organ dissemination in the adult rat. Intact EGF was recovered primarily from the tongue, parotid, and sublingual/submandibular glands after administration by sublingual lozenge, whereas gastrointestinal administration resulted in 125I-EGF recovery primarily from plasma, stomach, and lung. Recovered radiolabeled EGF retained the ability to bind to the EGF receptor. Sialoadenectomy caused an increase in 125I-EGF in most tissues by both routes of administration. Thus, in the adult rat, at least two pathways exist for the uptake and distribution for salivary gland-derived EGF present in saliva. With further analyses, sublingual absorbance of EGF may therefore provide a potential delivery route for therapeutic use of growth factor, which avoids the hepatic destruction of EGF after oral administration.

Colon cancer cells that are not growth inhibited by TGF-beta lack functional type I and type II TGF-beta receptors

OBJECTIVE

The authors determined the molecular mechanisms for the failure of transforming growth factor-beta (TGF-beta) to inhibit the growth of SW1116 and SW48 colon cancer cell lines.

BACKGROUND

Transforming growth factor-beta is a bifunctional regulator of cell growth that typically stimulates proliferation of mesenchymal cells, but inhibits proliferation of normal epithelial cells. In the colon, TGF-beta appears to arrest proliferation of enterocytes as they leave the intestinal crypt and move to the villus tip. Transforming growth factor-beta actions are mediated by binding to heteromeric complexes of type I and type II TGF-beta receptors. Loss of TGF-beta responsiveness may contribute to uncontrolled cell growth and cancer.

METHODS

The effects of TGF-beta 1 on DNA synthesis were measured by incorporation of tritiated thymidine into DNA of cultures of moderately differentiated adenocarcinoma (SW48) and poorly differentiated adenocarcinoma (SW1116) colon cell lines and a mink lung epithelial cell line (CCL-64). The effects of TGF-beta on the expression of c-myc, TGF-alpha, and TGF-beta in SW48 cells, SW1116 cells, and CCL-64 cells (c-myc only) were measured by Northern blot analysis. Expression of TGF-beta receptors in the cell lines was measured using competitive binding assays, receptor affinity labelling techniques, and reverse transcriptase-polymerase chain reaction.

RESULTS

Incubation with TGF-beta 1 (50 ng/mL) did not decrease serum-stimulated uptake of [3H]-thymidine into actively growing cultures of SW48 or SW1116 cells, but suppressed DNA synthesis of actively growing CCL-64 cells by 90%. Similarly, incubation with TGF-beta 1 (12 ng/mL) for 4 hours did not substantially alter the mRNA levels of c-myc, TGF-alpha, and TGF-beta 1 in either colon tumor cell line, although levels of c-myc mRNA in CCL-64 cells were reduced by TGF-beta 1 treatment. Competitive displacement of [125I]-TGF-beta 1 binding detected high levels (16,500 TGF-beta receptors per cell) of specific, high-affinity (200 pmol/L half-displacement) TGF-beta receptors on CCL-64 cells. In marked contrast, very low levels of TGF-beta 1 binding to SW1116 cells (250 receptors per cell) and SW48 cells (260 receptors per cell) were detected. Autoradiograms of CCL-64 cells affinity labelled with [125I]TGF-beta 1 revealed the presence of type I, type II, and type III TGF-beta receptors. No TGF-beta receptors were identified on SW1116 cells, and only very low levels of the nonsignaling type III TGF-beta receptors were detected on SW48 cells. Reverse transcriptase-polymerase chain reaction amplification detected mRNAs for type I, type II, and type III TGF-beta receptors in CCL-64 cells. SW48 cells, and SW1116 cells.

CONCLUSIONS

These results suggest that the lack of growth inhibition by TGF-beta in SW48 and SW1116 colon cancer cells may be caused by a lack of expression of functional TGF-beta receptors.

Expression of transforming growth factor alpha and its receptor in human neuroendocrine tumours

Transforming growth-factor-alpha (TGF-alpha) is a 50-amino-acid polypeptide that binds to the epidermal growth factor (EGF) receptor and stimulates cell growth. It has been suggested that enhanced production of TGF-alpha and EGF receptors by tumour cells promote tumour-cell growth by autocrine mechanisms. In the present study we have investigated the expression of TGF-alpha and EGF receptors in human neuroendocrine tumours, including midgut carcinoid tumours, phaeochromocytomas and medullary thyroid carcinomas. TGF-alpha expression was demonstrated in biopsies of all tumours examined (n = 30) and EGF receptors in a majority of tumours by Northern analysis and/or immunocytochemistry. Expression of TGF-alpha and EGF receptors was also demonstrated in primary cultures of tumour cells. Carcinoid tumours and phaeochromocytomas in culture secreted detectable amounts of TGF-alpha into the culture medium (400-700 pM). The amount of secreted TGF-alpha could be suppressed by octreotide treatment in individual tumours. Administration of exogenous TGF-alpha stimulated carcinoid tumour growth in vitro as determined by the DNA contents of cell cultures. The growth-stimulatory effect of TGF-alpha could be partially blocked by the use of neutralizing anti-EGF receptor monoclonal antibodies (MAbs). In conclusion, several human neuroendocrine tumours express both TGF-alpha and EGF receptors in in vivo and in vitro, suggesting that TGF-alpha may regulate tumour-cell growth by autocrine mechanisms.

Effect of epidermal growth factor, hepatocyte growth factor, and keratinocyte growth factor, on proliferation, motility and differentiation of human corneal epithelial cells

We sought to determine the effects of exogenous epidermal growth factor (EGF), heparin-binding EGF (HB-EGF), transforming growth factor alpha (TGF-alpha), single-chain precursor hepatocyte growth factor (SC-HGF), double-chain mature HGF (DC-HGF), and keratinocyte growth factor (KGF) on proliferation, motility, and differentiation of first passage cultures of human corneal epithelial cells in serum-free chemically defined medium. The effect of EGF, HB-EGF, TGF-alpha, SC-HGF, DC-HGF, KGF or combinations of the growth factors on proliferation was measured by counting cells present after 3 weeks of culture and by immunostaining for the cell-cycle-specific nuclear proliferation antigen Ki-67. The effect of the factors on epithelial cell motility was assessed by morphometric analysis of photographs of cells migrating from confluent islands of cells. The effect of growth factors on differentiation of epithelial cells were determined by immunostaining epithelial cell islands for the keratin K3 and by Western blotting for keratin K3. EGF, alone or in combination with KGF and SC-HGF, significantly stimulated motility of epithelial cells at the periphery of confluent islands of cells and induced an elongated cell morphology. TGF-alpha, HB-EGF and DC-HGF produced motility effects similar to EGF. There was diminished proliferation of the migrating cells in response to EGF, HB-EGF, TGF-alpha or DC-HGF, while non-migrating epithelial cells in the center of confluent islands continued to proliferate in response to the growth factors. EGF, HB-EGF, TGF alpha or DC-HGF inhibited expression of the differentiation-related marker keratin K3 in epithelial cells, both at the edge and at the center of the islands. KGF stimulated proliferation of corneal epithelial cells at low density and in confluent islands of cells. KGF did not affect expression of keratin K3 or migration of epithelial cells. SC-HGF had no effect on corneal epithelial cells. These results indicate that the effects of EGF, HB-EGF, TGF-alpha and DC-HGF on corneal epithelial cell proliferation, motility and differentiation vary from those of KGF and SC-HGF. EGF, HB-EGF, TGF-alpha and DC-HGF induced changes in epithelial cell morphology and motility in cells plated at low cell density or in cells located at the edge of a confluent island. Thus, these effects appear to be dependent on the extent of cell-cell contact. The inhibitory effect of EGF, HB-EGF, TGF-alpha or DC-HGF on corneal epithelial cell differentiation, however, is independent of cell density.(ABSTRACT TRUNCATED AT 400 WORDS)

Epidermal growth factor, transforming growth factor alpha, transforming growth factor beta, acidic fibroblast growth factor, basic fibroblast growth factor, and interleukin-1 proteins in the cornea

The purpose of this study was to determine whether epidermal growth factor (EGF), EGF receptor, transforming growth factor alpha (TGF-alpha), transforming growth factor beta (TGF-beta), acidic fibroblast growth factor (acidic-FGF), basic fibroblast growth factor (basic-FGF), and interleukin-1-alpha (IL-1-alpha) proteins were present in cultures of human corneal cells and/or in sections of human corneal tissue. Immunohistochemistry was performed on human corneal sections. Immunofluorescent cell staining was used to evaluate corneal epithelial, stromal fibroblast, and endothelial cells in primary culture. Basic-FGF production was evaluated in culture cells using immunoprecipitation. EGF, TGF-alpha, TGF-beta-1, and IL-1-alpha were detected by immunohistochemistry in cells in all three layers of the cornea. EGF receptor and acidic FGF were detected by immunohistochemistry in epithelial and endothelial cells, but not in stromal fibroblast cells. Differences in distribution of the growth factors were noted within individual layers of the cornea. EGF and basic-FGF proteins were detected in all three predominant cell types of the cornea using immunocytology. IL-1-alpha protein was detected by immunocytology in corneal epithelial and endothelial cells, but not stromal fibroblasts. Immunoprecipitation confirmed the production of basic-FGF in all three cell types. IL-1-alpha protein detection in the corneal stroma by immunohistology, but not by immunocytology in first passage stromal fibroblasts, suggests that IL-1-alpha may localize to the corneal stroma after production by corneal epithelial and/or endothelial cells.

Characterization of the synthesis and secretion of transforming growth factor-alpha from salivary glands and saliva

Whole saliva collected from rat, mouse, and human sources was found to contain high concentrations of transforming growth factor-alpha (TGF alpha) when analyzed by RIA. The concentrations of TGF alpha in unstimulated human saliva (age, 30-45 yr; n = 10; 1.5 +/- 3.1 nM) was reduced with age (age, 55-70 yr; n = 10; 0.4 +/- 0.1 nM), but increased in oral pathologies manifested in xerostomia (age, 57-70; n = 6; 0.8 +/- 0.2 nM) and Paget's disease (age, 58-76; n = 8; 2.0 +/- 0.6 nM). Immunohistochemical localization of TGF alpha in the salivary glands of rats and mice revealed specific immunostaining of the granular ductal cells of the parotid and submandibular glands. Reverse transcription followed by polymerase chain reaction amplification of total RNA from the parotid and submandibular glands of rats and mice demonstrated the presence of TGF alpha mRNA, suggesting endogenous synthesis by the salivary glands. Thus, salivary glands appear to be an exocrine source for a second member of the epidermal growth factor-like growth factor family in the oral cavity.

Elevation of transforming growth factor alpha in cat aqueous humor after corneal endothelial injury

PURPOSE

To determine if a scrape injury to cat corneal endothelial cells increases the level of mitogenic proteins such as transforming growth factor alpha (TGF alpha) in aqueous humor.

METHODS

Aqueous humor of cats was collected at 0, 2, 6, and 24 hours after wounding the endothelium by contact with a cannula tip. Aqueous humor samples collected from sham-wounded cats served as controls. Aqueous humor samples were analyzed for levels of protein, for mitogenic activity using incorporation of tritiated thymidine by cultures of bovine corneal endothelial cells, and for immunoreactive TGF alpha protein using a specific radioimmunoassay.

RESULTS

The average protein level in aqueous humor obtained before wounding was low (0.5 mg/ml), increased 26-fold at 2 hours after injury (13 mg/ml), then progressively decreased at 6 hours (8 mg/ml) and 24 hours (2 mg/ml). Levels of mitogenic activity of aqueous humor samples collected 2, 6, and 24 hours after wounding were 2-fold, 2.5-fold, and 0.6-fold higher, respectively, compared to the level of mitogenic activity measured in aqueous humor collected before wounding (0 hours) or in aqueous humor collected from sham-wounded eyes. TGF alpha concentration in aqueous humor collected before endothelial wounding was low (6.8 ng/ml), increased 14-fold 2 hours after wounding (97.4 ng/ml), then progressively decreased at 6 hours (63.3 ng/ml) and 24 hours (35.5 ng/ml) after wounding. TGF alpha concentrations in aqueous humor collected from sham-wounded eyes at 2 hours (9.5 ng/ml) and 6 hours (5.3 ng/ml) were not significantly different from prewound levels. Detergent extracts of bovine corneal endothelial cells contained substantial levels of TGF alpha immunoreactive protein (20 ng/mg protein).

CONCLUSIONS

Wounding of cat endothelium causes a rapid increase in mitogenic proteins in aqueous humor including TGF alpha, which may act by an autocrine mechanism to stimulate endothelial wound healing.

Growth factors in human tear fluid and in lacrimal glands

EGF has been shown to be a constant component of human tear fluid. Its concentration depends on the actual tear fluid flow, as shown for other proteins secreted by the lacrimal gland. This organ has also been considered to be the origin of tear fluid EGF and immunohistochemical evidence for this hypothesis was found. During corneal disease the concentration of EGF in tear fluid considerably decreases to levels even lower than those found during short time stimulation of reflex tearing. Other members of the EGF family, such as TGF-alpha, have considerable similarity with the EGF molecule and even bind to the same receptor. Currently it is thought that TGF-alpha may be, in certain phases of cell life, even more important in the regulation of cell metabolism than EGF. In the present study we have investigated the presence of TGF-alpha in tear fluid and the lacrimal gland. The initial results presented here, show for the first time that TGF-alpha like EGF, seems to be constant component of human tear fluid and to originate, at least partially, from the lacrimal gland.

TGF-alpha protein and receptor localization in laryngotracheal tissue

Both normal cell turnover and healing of laryngeal and tracheal injuries involve cell migration and mitosis. The proteins that regulate normal cell turnover and wound healing in the larynx and trachea have not been established. It is possible that peptide growth factors, such as transforming growth factor-alpha (TGF alpha) acting through its receptor (EGF/TGF alpha-R), participate in the regulation of these processes. To investigate this hypothesis, we analyzed laryngotracheal cells for TGF alpha protein and receptor in normal and postwounding conditions. TGF alpha protein was detected by immunohistochemical analysis in normal ferret laryngeal and tracheal mucosa. Specific binding to the EGF/TGF alpha receptor in membrane homogenates of ferret larynx and trachea reached saturation after 60 minutes at 37 degrees C, and was effectively displaced by unlabeled epidermal growth factor (EGF) or TGF alpha, but not by unlabeled insulin, angiotensin II, or basic fibroblast growth factor. Scatchard analysis of the specific binding indicated the presence of high-affinity (Kd = 117 pmol) and low-affinity (Kd = 40 nmol) binding sites. The maximum number of available binding sites was 73 fmol/mg protein. Localization of the EGF/TGF alpha receptor by autoradiographic analysis of 125I-EGF binding to sections of normal ferret larynx and trachea revealed EGF/TGF alpha receptors throughout the epithelium, with the highest grain density in the basal layers. Quantitative analysis of autoradiographic grain density between normal, intubated, and extubated animals revealed no significant differences. The presence of TGF alpha protein and its receptor in normal and wounded larynx and trachea supports the hypothesis that these proteins are involved in regulating physiologic responses of laryngotracheal cells.

Detection of epidermal growth factor and transforming growth factor alpha protein in meningiomas and other tumors of the central nervous system in human beings

Epidermal growth factor (EGF) and transforming growth factor alpha (TGF alpha) are potent mitogens for normal cells of ectodermal and mesodermal origin. Evidence is accumulating that suggests that EGF, TGF alpha and their common receptor (EGF/TGF alpha-R) influence development and functioning of tissues of the central nervous system (CNS). To further investigate the possible roles of EGF, TGF alpha and their receptor in autocrine/paracrine regulation of tumor growth in the CNS, a series of tumors of the CNS were analyzed for the presence of specific, high affinity EGF/TGF alpha receptors and for the presence of immunoreactive TGF alpha protein. Binding of 125I-EGF to crude membranes from a pool of meningiomas was competed for equally well by low concentrations of unlabeled EGF or TGF alpha, but not by high concentrations of other protein hormones, demonstrating the high degree of specificity of the EGF/TGF alpha receptor. Specific binding of 125I-EGF was dependent upon time and temperature, with maximum specific binding achieved after two hours at 22 degrees C. Scatchard analysis of six tumors of the CNS large enough to permit titration analysis generated linear plots with an average kilodalton of 1.1 +/- 0.1 nanometer (+/- standard error of the mean), suggesting the presence of a single class of EGF/TGF alpha-R with high affinity. EGF also stimulated phosphorylation of a 170 kilodalton protein in membrane fraction of a meningioma, demonstrating that the EGF/TGF alpha-R in this tumor retained EGF-stimulated kinase autophosphorylating activity. Membranes for 17 additional smaller tumors of the CNS were analyzed for specific binding of 125I-EGF by single, high concentration method, and all 17 tumors were found to contain specific binding of 125I-EGF. The average level of 125I-EGF for all 23 tumors of the CNS was 46 +/- 27 femtomoles per milligram protein with a range of 1 femtomoles per milligram for both a pituitary adenoma and meningioma to 638 femtomoles per milligram for a glioblastoma. A series of 13 tumors of the CNS were analyzed for EGF alpha with use of a specific radioimmunoassay. TGF alpha immunoreactive protein was detected in all four malignant tumors of the CNS assayed at an average level of 2.6 +/- 1.1 nanograms per milligram soluble protein, whereas TGF alpha immunoreactive protein was detected in only two of nine benign tumors of the CNS. These results add support to the hypothesis that TGF alpha and its receptor may act by autocrine/paracrine mechanisms to influence growth of tumors of the CNS in vivo.

Transforming growth factor-beta enhances connective tissue repair in perforated rat mesentery but not peritoneal macrophage chemotaxis

The perforated rat mesentery model was used to study the effect of transforming growth factor-beta (TGF-beta) on connective tissue repair and influx of macrophages into the peritoneal cavity during such repair. Sprague-Dawley rats were laparotomized, and mesenteric wounds were made with a scalpel. A daily intraperitoneal injection of 0.5 microg TGF-beta was given for either 2 or 4 days. After 1 to 10 days, the animals received an intravenous injection of tritium-labeled thymidine before decapitation. Macrophages were collected by peritoneal washing, and the number of closed perforations was counted. Peritoneal cells were quantitated and a labeling index was determined by autoradiography. TGF-beta given for either 2 (p < 0.001) or 4 (p < 0.004) days accelerated closure of perforations on days 3 to 7 after injury. Laparotomy as such significantly increased leukocyte influx (p < 0.004), as well as macrophage-labeling index (p < 0.02). However, TGF-beta did not significantly influence either leukocyte influx or macrophage-labeling index. We concluded that TGF-beta significantly enhances connective tissue repair in this perforated rat mesentery model and that TGF-beta-induced stimulation of repair is not caused by an increased influx of macrophages into the peritoneal cavity.

Growth factors and wound healing: Part II. Role in normal and chronic wound healing

Wound healing is a complex biologic process that involves the integration of inflammation, mitosis, angiogenesis, synthesis, and remodeling of the extracellular matrix. Part II of this two-part series reviews the results of experiments that indicate that growth factors and their receptors regulate key aspects of soft and hard tissue repair. Results of clinical studies are also reviewed that demonstrate that growth factor treatment accelerates healing of normal tissues and promotes healing of impaired wounds.

Growth factors and wound healing: biochemical properties of growth factors and their receptors

Wound healing is a complex biologic process that involves chemotaxis and division of cells, neovascularization, synthesis of extracellular matrix proteins, and remodeling of scar. Peptide growth factors have been shown to regulate many of these processes in vitro, leading to the hypothesis that peptide growth factors also regulate important phases of wound healing in vivo. Part I of this two-part series presents an overview of the biochemical properties of five families of peptide growth factors that are thought to be involved in wound healing: epidermal growth factor (EGF), transforming growth factor-beta (TGF-beta), platelet-derived growth factor (PDGF), insulin-like growth factor (IGF), and fibroblast growth factor (FGF).

Regulation of small intestinal glutamine transport by epidermal growth factor

BACKGROUND

Epidermal growth factor (EGF) stimulates cell replication and increases DNA content of the small intestine, but its effects on mucosal amino acid transport are unknown.

METHODS

To investigate these effects, we treated adult rats with vehicle or EGF (10 micrograms/100 gm body weight subcutaneously every 8 hours for three doses). Jejunal brush border membrane vesicles (BBMVs) from each group were prepared by Mg++ aggregation/differential centrifugation. BBMVs were enriched fifteen-fold in alkaline phosphatase, indicating BBMV purity. Transport of 3H-glutamine and 3H-alanine was studied by a rapid mixing filtration technique. Uptakes were primarily Na+ dependent, occurred in an osmotically active space, exhibited classic overshoots, and had similar 2-hour equilibrium values.

RESULTS

Glutamine transport by BBMVs more than doubled in rats treated with EGF (16.4 +/- 0.1 pmol glutamine/mg protein/10 sec in EGF vs 7.1 +/- 0.5 pmol glutamine/mg protein/10 sec in controls; p < 0.001). Kinetic studies of the glutamine transporter showed that the increase in transport was the result of a 70% increase in maximal transport velocity (total maximum glutamine uptake = 193 +/- 8 pmol glutamine/mg protein/10 sec in EGF vs 114 +/- 7 pmol glutamine/mg protein/10 sec in controls; p < 0.0001 with no change in transporter affinity (transporter affinity = 224 +/- 6 mumol/L in EGF vs 242 +/- 37 mumol/L in controls; difference, not significant). Alanine uptake by BBMVs was also increased with EGF administration (10.2 +/- 2.0 pmol alanine/mg protein/10 sec in EGF vs 4.5 +/- 0.5 pmol alanine/mg protein/10 sec in controls; p < 0.005). Simultaneously, glucose transport was decreased by 50% in EGF-treated rats, indicating that the Na(+)-dependent glucose cotransporter is regulated independently from and opposite to amino acid transporters.

CONCLUSIONS

We conclude that EGF up-regulates amino acid transport activity in jejunal BBMVs, an event that is most likely caused by an increase in de novo biosynthesis of transporter protein. The increase in amino acid uptake not only may support de novo protein synthesis but, in the case of glutamine, also may be required for energy production and nucleotide biosynthesis.