Differential expression and regulation of TGF-beta1, TGF-beta2, TGF-beta3, TGF-betaRI, TGF-betaRII and TGF-betaRIII in cultured human corneal, limbal, and conjunctival fibroblasts

Dental caries and periodontitis and the risk of myopia in young adults: CHIEF oral health study

Aim

Oral health and ocular diseases may be associated with collagen defects and inflammation status. However, the results from prior studies are conflicting. The aim of this study was to explore the association of dental caries and periodontitis with myopia in young adults.

Materials and methods

A total of 938 military personnel aged 19–39 years receiving both oral and eye examinations from 2018 through 2020 were included in this study in Taiwan. The severity of myopia was graded as no myopia (diopters > − 0.5, N = 459), low myopia (diopters: − 0.5 to -5.9, N = 225) and high myopia (diopters ≤ − 6.0, N = 254). A multiple logistic regression analysis with adjustments for age, body mass index, systolic blood pressure, smoking, alcohol consumption, missing teeth numbers, blood leucocyte counts, triglycerides, high-density lipoprotein, and uric acid were used to determine the associations of actively dental caries, filled teeth and stage II/III periodontitis with myopia.

Results

The presence of any actively dental caries was significantly associated with a higher risk of any myopia (low or high) (odds ratio [OR] and 95% confidence intervals [95% CI] 1.42 [1.04–1.94]), whereas there was no association for filled teeth. Moreover, the association for stage II/III periodontitis was only observed with high myopia (OR: 1.52 [1.07–2.15]) and was not observed with low myopia.

Conclusions

Our findings suggest that only actively dental caries and a higher severity of periodontitis were associated with myopia among young adults, thus highlighting the dental inflammation status in the oral cavity as a potential link to ocular diseases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02413-w.

TGFβ1 and TGFβ2 proteins in corneas with and without stromal fibrosis: Delayed regeneration of apical epithelial growth factor barrier and the epithelial basement membrane in corneas with stromal fibrosis

The purpose of this study was to investigate the expression and localization of transforming growth factor (TGF) β1 and TGFβ2 in rabbit corneas that healed with and without stromal fibrosis, and to further study defective perlecan incorporation in the epithelial basement membrane (EBM) in corneas with scarring fibrosis. A total of 120 female rabbits had no surgery, -4.5D PRK, or -9D PRK. Immunohistochemistry (IHC) was performed at time points from unwounded to eight weeks after surgery, with four corneas at each time point in each group. Multiplex IHC was performed for TGFβ1 or TGFβ2, with Image-J quantitation, and keratocan, vimentin, alpha-smooth muscle actin (SMA), perlecan, laminin-alpha 5, nidogen-1 or CD11b. Corneas at the four-week peak for myofibroblast and fibrosis development were evaluated using Imaris 3D analysis. Delayed regeneration of both an apical epithelial growth factor barrier and EBM barrier function, including defective EBM perlecan incorporation, was greater in high injury -9D PRK corneas compared to -4.5D PRK corneas without fibrosis. Defective apical epithelial growth factor barrier and EBM allowed epithelial and tear TGFβ1 and tear TGFβ2 to enter the corneal stroma to drive myofibroblast generation in the anterior stroma from vimentin-positive corneal fibroblasts, and likely fibrocytes. Vimentin-positive cells and unidentified vimentin-negative, CD11b-negative cells also produce TGFβ1 and/or TGFβ2 in the stroma in some corneas. TGFβ1 and TGFβ2 were at higher levels in the anterior stroma in the weeks preceding myofibroblast development in the -9D group. All -9D corneas (beginning two to three weeks after surgery), and four -4.5D PRK corneas developed significant SMA + myofibroblasts and stromal fibrosis. Both the apical epithelial growth factor barrier and/or EBM barrier functions tended to regenerate weeks earlier in -4.5D PRK corneas without fibrosis, compared to -4.5D or -9D PRK corneas with fibrosis. SMA-positive myofibroblasts were markedly reduced in most corneas by eight weeks after surgery. The apical epithelial growth factor barrier and EBM barrier limit TGFβ1 and TGFβ2 entry into the corneal stroma to modulate corneal fibroblast and myofibroblast development associated with scarring stromal fibrosis. Delayed regeneration of these barriers in corneas with more severe injuries promotes myofibroblast development, prolongs myofibroblast viability and triggers stromal scarring fibrosis.

Tumour dormancy in inflammatory microenvironment: A promising therapeutic strategy for cancer-related bone metastasis

Cancer metastasis is a unique feature of malignant tumours. Even bone can become a common colonization site due to the tendency of solid tumours, including breast cancer (BCa) and prostate cancer (PCa), to metastasize to bone. Currently, a previous concept in tumour metabolism called tumour dormancy may be a promising target for antitumour treatment. When disseminated tumour cells (DTCs) metastasize to the bone microenvironment, they form a flexible regulatory network called the "bone-tumour-inflammation network". In this network, bone turnover as well as metabolism, tumour progression, angiogenesis and inflammatory responses are highly unified and coordinated, and a slight shift in this balance can result in the disruption of the microenvironment, uncontrolled inflammatory responses and excessive tumour growth. The purpose of this review is to highlight the regulatory effect of the "bone-tumour-inflammation network" in tumour dormancy. Osteoblast-secreted factors, bone turnover and macrophages are emphasized and occupy in the main part of the review. In addition, the prospective clinical application of tumour dormancy is also discussed, which shows the direction of future research.

HC-HA/PTX3 Purified From Human Amniotic Membrane Reverts Human Corneal Fibroblasts and Myofibroblasts to Keratocytes by Activating BMP Signaling

Purpose

Fibrosis or scarring is a pathological outcome of wound healing and is characterized by terminally differentiated myofibroblasts. Heavy chain-hyaluronic acid/pentraxin 3 (HC-HA/PTX3) is a unique matrix component purified from amniotic membrane that exerts an anti-inflammatory effect. Herein, we investigate whether HC-HA/PTX3 can also exert an antiscarring effect.

Methods

Human corneal fibroblasts and myofibroblasts were seeded on plastic, immobilized HA or HC-HA/PTX3 or on plastic with or without soluble HA and HC-HA/PTX3 in DMEM+10% FBS, with or without AMD3100 or SB431542 in DMEM+ITS with or without transforming growth factor–β1 (TGF-β1). Transcript expression of keratocyte and signaling markers was determined by RT-qPCR. Immunostaining was performed to monitor cytolocalization of signaling markers and α-SMA. Western blotting was used to measure relative protein level.

Results

Human corneal fibroblasts and myofibroblasts cultured in or on HC-HA/PTX3, but not HA, were refrained from cytoplasmic expression of αSMA and nuclear translocation of pSMAD2/3 when challenged with exogenous TGF-β1. Such an antiscarring action by suppressing canonical TGF-β1 signaling was surprisingly accompanied by phenotypic reversal to keratocan-expressing keratocytes through activation of BMP signaling. Further investigation disclosed that such phenotypic reversal was initiated by cell aggregation mediated by SDF1-CXCR4 signaling highlighted by nuclear translocation of CXCR4 and upregulation of CXCR4 transcript and protein followed by activation of canonical BMP signaling.

Conclusions

These findings collectively provide mechanistic understanding explaining how amniotic membrane transplantation exerts an antiscarring action. In addition, HC-HA/PTX3 and derivatives may be developed into a new biologic to treat corneal blindness caused by stromal scar or opacity in the future.

Comparison of cytokine expression and ultrastructural alterations in fresh-frozen and dried electron beam-irradiated human amniotic membrane and chorion

The purpose of the current study was to compare the effects of drying and fresh-freezing on human amniotic membrane (HAM) and amnion/chorion membrane (HACM) in terms of histological and structural characteristics and cytokine levels. HAM and HACM samples, obtained from six placentae, were investigated. HAM and HACM were dried, electron beam-irradiated (dehydration group; d-HAM/d-HACM), or fresh-frozen (freezing group; f-HAM/f-HACM). Luminex assay was used to assay the levels of 15 cytokines. The ultrastructural characteristics of HAM and HACM were evaluated using light and transmission electron microscopies. Total cytokine contents did not show the statistical difference between dehydration and fresh-freezing process. Significantly higher levels of total cytokines were observed in HACM than in HAM. Epidermal growth factor (EGF) level was significantly higher in d-HAM than in the other samples. The levels of most of the other growth factors were higher in HACM than in HAM, but there was no statistical difference between the dehydration process and the fresh-freezing process. The levels of the cytokines, other than the growth factors, were higher in HACM than in HAM, and higher concentrations of cytokines were observed in the freezing group than in the dehydration group. Histological examination revealed that the dehydration group had thinner tissues than the freezing group, but the structural stability, including the basement membrane, did not differ between the two groups. Microscopic structures such as microvilli and nuclei were well-preserved in the freezing group, based on the results of the transmission electron microscopy. Our dehydration process maintained the histological structure of HAM/HACM and a variety of growth factors and cytokines were identified. Especially, the HAM, processed with the dehydration method, had a higher EGF level than that processed with the fresh-freezing method. Therefore, dehydration method can be used to effectively promote wound repair.

MEK inhibition prevents TGF‑β1‑induced myofibroblast transdifferentiation in human tenon fibroblasts

Subconjunctival fibrosis represents the primary cause of postoperative failure of trabeculectomy, and at present there is a lack of effective intervention strategies. The present study aimed to investigate the effect of the mitogen‑activated protein kinase kinase (MEK) inhibitor U0126 on human tenon fibroblast (HTF) myofibrosis transdifferentiation, and to illuminate the underlying molecular mechanisms involved. It was demonstrated that U0126 significantly inhibited the proliferation, migration and collagen contraction of HTFs stimulated with TGF‑β1. In addition, U0126 largely attenuated the TGF‑β1‑induced conversion of HTFs into myofibroblasts, as indicated by a downregulation of the mRNA and protein expression of α‑smooth muscle actin and zinc finger protein SNAI1, and by ameliorating the 3D‑collagen contraction response. Mechanistically, U0126 suppressed the TGF‑β1‑stimulated phosphorylation of mothers against decapentaplegic homolog 2/3, P38 mitogen‑activated protein kinase and extracellular signal‑regulated kinase 1/2, indicating that U0126 may inhibit HTF activation through the canonical and non‑canonical signaling pathways of TGF‑β1. Therefore, U0126 exhibits a potent anti‑fibrotic effect among HTFs, and the inhibition of MEK signaling may serve as an alternative intervention strategy for the treatment of trabeculectomy‑associated fibrosis.

Modulation of Fibroblasts in Conjunctival Wound Healing

Modulating conjunctival wound healing has the potential to improve outcomes after glaucoma filtration surgery and for several ocular disorders, including ocular cicatrial pemphigoid, vernal keratoconjunctivitis, and pterygium. Although anti-inflammatories and antimetabolites have been used with success, these nonspecific agents are not without their complications. The search for novel and more targeted means to control conjunctival fibrosis without such limitations has brought much attention to the regulation of fibroblast proliferation, differentiation, extracellular matrix production, and apoptosis. This review provides an update on where we stand with current antifibrotic agents and outlines the strategies that novel agents use, as they evolve from the bench to the bedside.

Custom RT-qPCR-array for glaucoma filtering surgery prognosis

Excessive subconjunctival scarring is the main reason of failure of glaucoma filtration surgery. We analyzed conjunctival and systemic gene expression patterns after non penetrating deep sclerectomy (NPDS). To find expression patterns related to surgical failure and their correlation with the clinical outcomes. This study consisted of two consecutive stages. The first was a prospective analysis of wound-healing gene expression profile of six patients after NPDS. Conjunctival samples and peripheral blood samples were collected before and 15, 90,180, and 360 days after surgery. In the second stage, we conducted a retrospective analysis correlating the late conjunctival gene expression and the outcome of the NPDS for 11 patients. We developed a RT-qPCR Array for 88 key genes associated to wound healing. RT-qPCR Array analysis of conjunctiva samples showed statistically significant differences in 29/88 genes in the early stages after surgery, 20/88 genes between 90 and 180 days after surgery, and only 2/88 genes one year after surgery. In the blood samples, the most important changes occurred in 12/88 genes in the first 15 days after surgery. Correspondence analyses (COA) revealed significant differences between the expression of 20/88 genes in patients with surgical success and failure one year after surgery. Different expression patterns of mediators of the bleb wound healing were identified. Examination of such patterns might be used in surgery prognosis. RT-qPCR Array provides a powerful tool for investigation of differential gene expression wound healing after glaucoma surgery.

Role of Chronic Inflammation in Myopia Progression: Clinical Evidence and Experimental Validation

Prevention and treatment of myopia is an important public problem worldwide. We found a higher incidence of myopia among patients with inflammatory diseases such as type 1 diabetes mellitus (7.9%), uveitis (3.7%), or systemic lupus erythematosus (3.5%) compared to those without inflammatory diseases (p < 0.001) using data from children (< 18 years old) in the National Health Insurance Research database. We then examined the inhibition of myopia by atropine in Syrian hamsters with monocular form deprivation (MFD), an experimental myopia model. We found atropine downregulated inflammation in MFD eyes. The expression levels of c-Fos, nuclear factor κB (NFκB), interleukin (IL)-6, and tumor necrosis factor (TNF)-α were upregulated in myopic eyes and downregulated upon treatment with atropine. The relationship between the inflammatory response and myopia was investigated by treating MFD hamsters with the immunosuppressive agent cyclosporine A (CSA) or the inflammatory stimulators lipopolysaccharide (LPS) or peptidoglycan (PGN). Myopia progression was slowed by CSA application but was enhanced by LPS and PGN administration. The levels of c-Fos, NF-κB, IL-6, and TNF-α were upregulated in LPS- and PGN-treated eyes and downregulated by CSA treatment. These findings provide clinical and experimental evidence that inflammation plays a crucial role in the development of myopia.

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Patients with inflammatory diseases have a higher incidence of myopia compared to those without inflammatory diseases.

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The expression levels of c-Fos, NFκB, IL-6, and TNF-α, which have known roles in chronic inflammation, were upregulated in myopic eyes.

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Atropine inhibited the progression of myopia by downregulating c-Fos, NFκB, IL-6, and TNF-α.

Myopia is an important and common eye disease that can lead to legal blindness. The relationship between myopia and inflammatory responses has never been studied. We demonstrated that increased inflammation in the eye promotes progression of myopia, whereas decreased inflammation slows the development of myopia.

Myofibroblasts

Myofibroblasts are activated in response to tissue injury with the primary task to repair lost or damaged extracellular matrix. Enhanced collagen secretion and subsequent contraction - scarring - are part of the normal wound healing response and crucial to restore tissue integrity. Due to myofibroblasts ability to repair but not regenerate, accumulation of scar tissue is always associated with reduced organ performance. This is a fair price to pay by the body for not falling apart. Whereas myofibroblasts typically vanish after successful repair, dysregulation of the normal repair process can lead to persistent myofibroblast activation, for instance by chronic inflammation or mechanical stress in the tissue. Excessive repair leads to the accumulation of stiff collagenous ECM contractures - fibrosis - with dramatic consequences for organ function. The clinical need to terminate detrimental myofibroblast activities has stimulated researchers to answer a number of essential questions: where do myofibroblasts come from, what are the factors leading to their activation, how do we discriminate myofibroblasts from other cells, what is the molecular basis for their contractile activity, and how can we stop or at least control them? This article reviews the current state of the myofibroblast literature by emphasizing their role in ocular repair and fibrosis. It appears that although the eye is quite an extraordinary organ, ocular myofibroblasts behave or misbehave just like their siblings in other organs.

Corneal myofibroblast biology and pathobiology: generation, persistence, and transparency

Important advances have led to a better understanding of the biology and pathobiology of corneal myofibroblasts and their generation after surgery, injury, infection and disease. Transforming growth factor (TGF) beta, along with platelet-derived growth factor (PDGF) and interleukin (IL)-1, has been shown to regulate myofibroblast development and death in in-vitro and in-situ animal models. The myofibroblast precursor cells regulated by these cytokines include both keratocyte-derived and bone marrow-derived cells. Cytokines that promote and maintain myofibroblasts associated with late haze after photorefractive keratectomy are modulated in part by the epithelial basement membrane functioning as barrier between the epithelium and stroma. Structural and functional defects in the basement membrane likely lead to prolonged elevation of TGFβ, and perhaps other cytokine, levels in the stroma necessary to promote differentiation of myofibroblasts. Conversely, repair of the epithelial basement membrane likely leads to a decrease in stromal TGFβ levels and apoptosis of myofibroblasts. Repopulating keratocytes subsequently reorganize the associated fibrotic extracellular matrix deposited in the anterior stroma by the myofibroblasts. Investigations of myofibroblast biology are likely to lead to safer pharmacological modulators of corneal wound healing and transparency.

Responses of cultured human keratocytes and myofibroblasts to ethyl pyruvate: a microarray analysis of gene expression

PURPOSE

Ethyl pyruvate (EP) has pharmacologic effects that remediate cellular stress. In the organ-cultured murine lens, EP ameliorates oxidative stress, and in a rat cataract model, it attenuates cataract formation. However, corneal responses to EP have not been elucidated. In this study, the potential of EP as a therapeutic agent in corneal wound healing was determined by examining its effects on the transition of quiescent corneal stromal keratocytes into contractile myofibroblasts.

METHODS

Three independent preparations of cultured human keratocytes were treated with TGF-beta1, to elicit a phenotypic transition to myofibroblasts in the presence or absence of 10 or 15 mM EP. Gene expression profiles of the 12 samples (keratocytes +/- EP +/- TGF-beta1 for three preparations) were produced by using gene microarrays.

RESULTS

TGF-beta1-driven twofold changes in at least two of three experiments defined a group of 1961 genes. Genes showing twofold modulation by EP in at least two experiments appeared exclusively in myofibroblasts (857 genes), exclusively in keratocytes (409 genes), or in both phenotypes (252 genes). Analysis of these three EP-modulated groups showed that EP (1) inhibited myofibroblast proliferation with concomitant modulation of some cell cycle genes, (2) augmented the NRF2-mediated antioxidant response in both keratocytes and myofibroblasts, and (3) modified the TGF-beta1-driven transition of keratocytes to myofibroblasts by inhibiting the upregulation of a subset of profibrotic genes.

CONCLUSIONS

These EP-induced phenotypic changes in myofibroblasts indicate the potential of EP as a therapeutic agent in corneal wound healing.

Effect of the ocular microenvironment in regulating corneal dendritic cell maturation

OBJECTIVE

To determine whether the ocular anterior segment (aqueous humor and cornea) actively inhibits dendritic cell (DC) maturation.

METHODS

Dendritic cells were injected into syngeneic corneas or conjunctivae, and their surface major histocompatibility complex class II expression in response to the local milieu was assessed using confocal microscopy. Immature DCs were cocultured with corneal supernatant or with aqueous humor to evaluate their regulation of DC phenotypic and functional maturity.

RESULTS

In contrast to conjunctivally injected DCs, DCs injected into the cornea resisted up-regulation in expression of surface major histocompatibility complex class II. Corneal supernatant-treated and aqueous humor-treated DCs retained their immaturity, as reflected by high antigen uptake but low costimulatory molecule (CD80 and CD86) expression and poor T-cell stimulation. Anti-transforming growth factor beta(2) treatment of aqueous humor and of corneal supernatant led to complete and partial blockade of their inhibition of DC maturation, respectively. However, alpha-melanocyte-stimulating hormone and calcitonin gene-related peptide had no demonstrable effect on DC maturation.

CONCLUSION

Cornea and aqueous humor, principally through transforming growth factor beta(2,) promote generation of phenotypically and functionally immature DCs. Clinical Relevance Our results indicate that relative immune quiescence in the cornea and in the anterior segment is actively maintained in part by the inhibitory effect of transforming growth factor beta(2) on resident DCs and by their suppression of T-cell-mediated immune and inflammatory responses.

Increased Levels of Transforming Growth Factor-Beta1 and -Beta2 in the Aqueous Humor of Patients With Neovascular Glaucoma

BACKGROUND AND OBJECTIVE

To measure the concentrations of transforming growth factor-betal and beta2 (TGF-beta1 and TGF-beta2) in the aqueous humor of patients with neovascular glaucoma (NVG).

PATIENTS AND METHODS

Patients were divided into four groups: NVG secondary to central retinal vein occlusion (group 1), NVG secondary to proliferative diabetic retinopathy (group 2), central retinal vein occlusion without rubeosis (group 3), and senile cataract (group 4). The total TGF-beta 1 and TGF-beta2 concentrations in the aqueous humor of the four groups were measured by enzyme linked immunosorbent assay.

RESULTS

The mean concentrations of total TGF-betal were 600.7 +/-436.7 microg/mL in group 1, 802.0 +/-359.5 pg/mL in group 2, and undetectable in groups 3 and group 4 (P < .05). The mean concentrations of total TGF-beta2 were 6,307.9+/- 2,206.2 microg/mL in group 1, 5,908.0+/-2,033.2 microg/mL in group 2, 899.7+/- 425.6 microg/mL in group 3, and 385.7 +/-89.9 microg/mL in group 4. The total TGF-betal and TGF-beta2 concentrations in groups 1 and 2 were significantly higher than those in groups 3 and 4, whereas the total TGF-beta2 concentration in group 3 was significantly higher than that in group 4 (P < .05). There was no significant difference in the TGF-betal or TGF-beta2 concentrations between groups 1 and 2 (P> .05).

CONCLUSIONS

The abnormally high concentrations of TGF-betal and TGF-beta2 in the aqueous humor of patients with NVG may explain some aspects of the pathogenesis of NVG and the high failure rate of filtering operations in NVG.

How the cornea heals: cornea-specific repair mechanisms affecting surgical outcomes

In mammals, penetrating injuries typically heal by deposition of fibrotic "repair tissue" that fills and seals wounds but does not restore normal function. Excessive deposition of fibrotic repair tissue can lead to pathologies involving excessive scarring and contracture. In the cornea, fibrotic repair presents special challenges affecting both clarity and shape of the cornea. With the increasing popularity of surgical techniques that alter corneal refractive errors, understanding of cornea repair mechanisms has acquired new significance. The cornea has unique anatomic, cellular, molecular, and functional features that lead to important mechanistic differences in the process of repair in comparison with what occurs in skin and other organs. Moreover, corneal function calls for special outcomes. This review addresses these features from the viewpoint of the authors' research on factors of importance to understanding and improving surgical outcomes.

Localization of candidate stem and progenitor cell markers within the human cornea, limbus, and bulbar conjunctiva in vivo and in cell culture

Corneal diseases are some of the most prevalent causes of blindness worldwide. While the most common treatment for corneal blindness is the transplantation of cadaver corneas, expanded limbal stem cells are finding recent application. Unknown, however, is the identity of the actual repopulating stem cell fraction utilized in both treatments and the critical factors governing successful engraftment and repopulation. In order to localize potential stem cell populations in vivo, we have immunohistochemically mapped a battery of candidate stem and progenitor cell markers including c-Kit and other growth factor receptors, nuclear markers including DeltaNp63, as well as adhesion factors across the cornea and distal sclera. Cell populations that differentially and specifically stained for some of these markers include the basal and superficial limbal/conjunctival epithelium and scattered cells within the substantia propria of the bulbar conjunctiva. We have also determined that the culture of differentiated cornea epithelial cells as dissociated and explant cultures induces the expression of several markers previously characterized as candidate limbal stem cell markers. This study provides a foundation to explore candidate corneal stem cell populations. As well, we show that expression of traditional stem cell markers may not be reliable indicator of stem cell content during limbal stem cell expansion in vitro and could contribute to the variable success rates of corneal stem cell transplantation.

Comparative effects of TGF-β1 and TGF-β2 on extracellular matrix production, proliferation, migration, and collagen contraction of human Tenon's capsule fibroblasts in pseudoexfoliation and primary open-angle glaucoma

PURPOSE

To comparatively investigate the effects of TGF-beta(1) and TGF-beta(2) on extracellular matrix production, proliferation, migration, and collagen contraction of cultured human Tenon's capsule fibroblasts derived from patients with pseudoexfoliation (PEX) syndrome, PEX glaucoma, primary open-angle glaucoma (POAG), and cataract.

METHODS

Tenon's capsule fibroblasts obtained from four groups of patients were cultured and stimulated with different concentrations (0.1-10 ng ml(-1)) of TGF-beta(1) or TGF-beta(2) for up to 14 days. Cell proliferation was determined with the WST-1 colorimetric assay, cell migration by using the Transwell assay system, and collagen contraction by computerised analysis of three-dimensional collagen lattices and immunohistochemistry for alpha-smooth muscle actin expression. Expression and synthesis of extracellular matrix components (fibronectin, collagen types I and III) was assessed by enzyme-linked immunosorbent assays, by real-time RT-PCR, and by transmission electron microscopy.

RESULTS

Both TGF-beta(1) and TGF-beta(2) in pathophysiological concentrations of 0.1-5 ng ml(-1) stimulated cell proliferation, migration, collagen contraction, alpha-smooth muscle actin expression as well as mRNA expression and secretion of fibronectin, collagen type I, and collagen type III by Tenon's fibroblasts derived from all groups of patients. TGF-beta stimulation occurred in a concentration-dependent manner with different peak activities associated with different fibroblast functions. There was some variability among the different groups of patients with an increased response of cells derived from PEX and POAG patients as compared to cataract patients. Although no statistically significant differences were found between both TGF-beta isoforms, TGF-beta(1) had a more pronounced stimulatory effect on expression and synthesis of extracellular matrix components including the production of elastic microfibrils, particularly in cells derived from patients with PEX syndrome/glaucoma.

CONCLUSIONS

These findings suggest a significant contribution of TGF-beta(1) in addition to TGF-beta(2) to the conjunctival scarring process following glaucoma filtration surgery. Due to its pronounced fibrogenic potential, TGF-beta(1) may become another focus for targeting drug therapy, particularly in patients with PEX glaucoma.

Cultured tubule cells from TGF-beta1 null mice exhibit impaired hypertrophy and fibronectin expression in high glucose

BACKGROUND

To firmly establish the role of the transforming growth factor-beta1 (TGF-beta1) isoform in the pathophysiology of diabetic tubulointerstitial hypertrophy and fibrosis, we examined how the total absence of TGF-beta1 would alter the effect of high glucose on cellular hypertrophy and matrix expression in tubuloepithelial cells cultured from TGF-beta1 null mice.

METHODS

Primary tubule cell cultures, obtained from kidneys of TGF-beta1 knockout mice and their wild-type littermates, were treated with exogenous TGF-beta1 or high glucose. The TGF-beta system was characterized at the ligand and receptor levels using Northern and Western blotting. Cellular hypertrophy and growth were assessed by thymidine incorporation, cell counting, leucine incorporation, and protein content. Fibronectin expression was assessed by Northern analysis and enzyme-linked immunosorbent assay (ELISA).

RESULTS

Knockout cells did not express TGF-beta1 but did express TGF-beta2, TGF-beta3, and TGF-beta type I and type II receptors. Exogenous TGF-beta1 down-regulated the ligand-binding type II receptor but up-regulated type I receptor expression. Knockout cells proliferated more rapidly than wild-type cells, but restoring TGF-beta1 to knockout cells slowed their proliferation. In wild-type cells, high glucose caused cellular hypertrophy, evidenced by greater leucine incorporation and protein content along with decreased thymidine incorporation. High glucose also increased fibronectin message and protein. However, in knockout cells, high glucose failed to induce hypertrophy and was severely limited in its capacity to stimulate fibronectin.

CONCLUSION

In tubular epithelial cells, TGF-beta1 mediates the hypertrophic and fibronectin-stimulatory effects of high glucose, confirming the role of the TGF-beta1 isoform in the pathogenesis of diabetic tubular hypertrophy and fibronectin overexpression.

Stem cells in the eye

In the adult organism, all tissue renewal and regeneration depends ultimately on somatic stem cells, and the eye is no exception. The importance of limbal stem cells in the maintenance of the corneal epithelium has long been recognised, and such cells are now used clinically for repair of a severely damaged cornea. The slow cycling nature of lens epithelial cells and their ability to terminally differentiate into fiber cells are suggestive of a stem cell lineage. Furthermore, recent studies have identified progenitor cells in the retina and ocular vasculature which may have important implications in health and disease. Although the recent literature has become flooded with articles discussing aspects of stem cells in a variety of tissues our understanding of stem cell biology, especially in the eye, remains limited. For instance, there is no definitive marker for ocular stem cells despite a number of claims in the literature, the patterns of stem cell growth and amplification are poorly understood and the microenvironments important for stem cell regulation and differentiation pathways are only now being elucidated. A greater understanding of ocular stem cell biology is essential if the clinical potential for stem cells is to be realised. For instance; How do we treat stem cell deficiencies? How do we use stem cells to regenerate damaged retinal tissue? How do we prevent stem cell lineages contributing to retinal vascular disease? This review will briefly consider the principal stem cells in the mature eye but will focus in depth on limbal stem cells and corneal epithelium. It will further discuss their role in pathology and their potential for therapeutic intervention.

TGF-beta1 stimulates production of gelatinase (MMP-9), collagenases (MMP-1, -13) and stromelysins (MMP-3, -10, -11) by human corneal epithelial cells

Matrix metalloproteinases (MMPs) have been implicated in the pathogenesis of ocular surface diseases. This study investigated the regulated expression of gelatinases (MMP-2 and -9), collagenases (MMP-1 and -13) and stromelysins (MMP-3, -10, and -11) by TGF-beta1 in cultured human corneal epithelial cells. Primary human corneal epithelial cell cultures were grown to confluence and treated with different concentrations (0.1, 1.0, 10 ng ml(-1)) of TGF-beta1 in serum-free medium for 6-24 hr. Total RNA was isolated from cultured cells with or without TGF-beta1 treatment for 6 hr and subjected to semi-quantitative RT-PCR and Northern hybridization. Conditioned media were collected from cultures with or without TGF-beta1 treatment for 24 hr to evaluate the MMP production by ELISA and activity assays. Semi-quantitative RT-PCR revealed that the expressions of MMP-9, -1, -13, -3, -10 and -11 mRNA were up-regulated by TGF-beta1 in a concentration-dependent fashion, while MMP-2 and MMP-14 production did not change. Northern hybridization confirmed these findings. Gelatin zymography, MMP ELISA and activity assays showed concentration-dependent stimulated production and activity of MMP-9, -1, -13, -3 and -10 protein in the conditioned media of cultures treated for 24 hr with TGF-beta1. In conclusion, our results demonstrate that TGF-beta1 stimulates the expression and production of gelatinase (MMP-9), collagenases (MMP-1, -13) and stromelysins (MMP-3, -10, -11) in human corneal epithelial cells. These findings suggest that TGF-beta1 may play a role in the pathogenesis of MMP mediated ocular surface diseases, such as sterile corneal ulceration.

Pathogenesis of pterygia: role of cytokines, growth factors, and matrix metalloproteinases

Pterygium is a common ocular surface disease apparently only observed in humans. Chronic UV exposure is a widely accepted aetiological factor in the pathogenesis of this disease and this concept is supported by epidemiological data, ray tracing models and histopathological changes that share common features with UV damaged skin. The mechanism(s) of pterygium formation is incompletely understood. Recent data have provided evidence implicating a genetic component, anti-apoptotic mechanisms, cytokines, growth factors, extracellular matrix remodelling (through the actions of matrix metalloproteinases), immunological mechanisms and viral infections in the pathogenesis of this disease. In this review, the current knowledge on pterygium pathogenesis is summarised, highlighting recent developments. In addition, we provide novel data further demonstrating the complexity of this intriguing disease.

Effect of ectopic epithelial tissue within the stroma on keratocyte apoptosis, mitosis, and myofibroblast transformation

The purpose of this study was to examine the effects of the epithelium on processes involved in stromal wound healing. Lamellar epithelial-stromal flaps were produced in rabbit corneas with a microkeratome. Peripheral corneal epithelial tissue, central corneal epithelial tissue, or no epithelial tissue (control) was introduced beneath the flap. Corneas were removed at time points from 4 hr to 1 month after surgery. Tissue sections were analyzed with immunocytochemistry for Keratin 3 (K3) to detect epithelial antigen, terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick-end labelling (TUNEL) assay to detect apoptosis, immunocytochemistry for Ki67 to detect cell proliferation, and immunocytochemistry for alpha-smooth muscle actin (SMA) to detect myofibroblasts. K3 was detected at the level of the interface from 4 hr to 1 month after surgery in corneas in which epithelial tissue was introduced, but not control corneas, with the exception of one that developed epithelial in growth. Keratocyte apoptosis was significantly higher at 4 hr after flap formation in both groups in which corneal epithelial tissue was introduced beneath the flap compared with controls. Keratocyte proliferation was significantly greater at 72 hr in corneas in which epithelial tissue was introduced beneath the flap compared to the controls. Corneas in which epithelial tissue was introduced into the interface, but not control corneas, had stromal cells expressing alpha-SMA in the stroma anterior and posterior to the interface at 1 week and 1 month after surgery. This was also noted in the control cornea in which there was epithelial ingrowth. Signals derived from the corneal epithelium promote keratocyte apoptosis. Keratocyte proliferation is higher in corneas that have lamellar surgery when epithelial tissue is introduced into the interface. Epithelium-derived signals also participate in the generation and/or maintenance of myofibroblasts in the corneal stroma.

Interactions of corneal cells with transforming growth factor β2-modified poly dimethyl siloxane surfaces

The downgrowth of corneal epithelial cells at the interface of an artificial cornea and the host eye tissue poses a significant problem to be overcome in developing a successful implant. As a means of inhibiting the proliferation of corneal epithelial cells on the stromal surface of the implant, we examined the immobilization of transforming growth factor beta-2 (TGF-beta2) via a bifunctional poly ethylene glycol (PEG) spacer to poly dimethyl siloxane (PDMS) surfaces. Growth factor immobilization was confirmed by modification with (125)I-labeled TGF-beta 2. The modified surfaces were also characterized by advancing water contact angles, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Although the amount of growth factor covalently bound to the surface was difficult to quantify apparently due to strong interactions between the growth factor and the PEG layer and high levels of adsorption, differences in the modified surfaces, suggestive of the presence of a significant amount of TGF-beta 2, were found. In vitro interactions of the modified surfaces with human corneal epithelial and stromal cells were examined. Growth factor surface concentrations as well as culture in the absence and presence of serum and other adhesive proteins were examined. Corneal stromal and epithelial cells cultured on the TGF-beta 2-modified surfaces consistently gave results opposite to those expected. Likely, the most notable and surprising result was the almost complete lack of adhesion of the stromal cells, with coverage averaging between 3 and 5%. In comparison, corneal epithelial cell growth appeared to be promoted by the presence of the immobilized growth factor, with cell coverage averaging 50-60% at 7 days of culture. A TGF-beta 2 concentration effect was noted with both cell types in the absence of serum, with increases in the coverage at higher TGF-beta 2 concentrations. The observed cell growth appeared to be the result of interactions between the cells and active growth factor, because the addition of anti-TGF-beta 2 to the culture medium reduced cell coverage to levels similar to those noted on control surfaces. Therefore, although TGF-beta 2-modified surfaces may not be suitable as corneal epithelial cell inhibiting surfaces, interactions of surface immobilized growth factor and corneal cells are complex and should be further examined.

Molecular cloning of wound inducible transcript (wit 3.0) differentially expressed in edentulous oral mucosa undergoing tooth extraction wound-healing

Tooth extraction is the most commonly prescribed ablation surgery in dentistry and results in the formation of edentulous mucosa. Although the edentulous mucosa serves as the critical interfacial tissue for removable and implant-assisted prostheses, the structure and physiology of this wound-induced tissue are largely uninvestigated. We addressed the hypothesis that tooth extraction activates the expression of a unique set of genes in healing edentulous mucosa. Using the Differential Display Polymerase Chain Reaction and 5' Rapid Amplification of cDNA Ends protocols, we isolated overlapping cDNAs encoding a 3.0-kb-long mRNA, Wound Inducible Transcript, 3.0 (wit 3.0). In situ hybridization demonstrated that wit 3.0 was primarily expressed by the fibroblasts associated with tooth extraction wound-healing. Appearing to generate from the wit 3.0 gene, two alternative transcripts presented, encoding 215-(wit 3.0 alpha) and 253-(wit 3.0 beta) amino-acid-long peptides with the characteristics of an intracellular molecule. Analysis of these data may provide new clues to the molecular mechanism of edentulous mucosa formation.

Basic fibroblast growth factor induces TGF-beta release in an isoform and glioma-specific manner

The aim of the current study was to determine whether basic fibroblast growth factor (bFGF), regulates the release of transforming growth factor-beta1 (TGF-beta1) from C6 glioma cells. The results of the study show that bFGF (2, 5 and 10 ng/ml) dose dependently induced the release of TGF-beta1 from C6 glioma cells, with the 10 ng/ml dose inducing a 2- to 3-fold increase of TGF-beta1 levels. This effect was evident as early as 6 h following treatment, with maximal levels observed at 18 h. The effect of bFGF was largely on latent TGF-beta1, and was isoform specific, as bFGF had no effect on TGF-beta2 release. The bFGF effect on TGF-beta1 was also glioma specific, as no such stimulatory effect was observed in rat cortical astrocytes.

Genomic structure, chromosomal localization and expression profile of a novel melanoma differentiation associated (mda-7) gene with cancer specific growth suppressing and apoptosis inducing properties

Abnormalities in cellular differentiation are frequent occurrences in human cancers. Treatment of human melanoma cells with recombinant fibroblast interferon (IFN-beta) and the protein kinase C activator mezerein (MEZ) results in an irreversible loss in growth potential, suppression of tumorigenic properties and induction of terminal cell differentiation. Subtraction hybridization identified melanoma differentiation associated gene-7 (mda-7), as a gene induced during these physiological changes in human melanoma cells. Ectopic expression of mda-7 by means of a replication defective adenovirus results in growth suppression and induction of apoptosis in a broad spectrum of additional cancers, including melanoma, glioblastoma multiforme, osteosarcoma and carcinomas of the breast, cervix, colon, lung, nasopharynx and prostate. In contrast, no apparent harmful effects occur when mda-7 is expressed in normal epithelial or fibroblast cells. Human clones of mda-7 were isolated and its organization resolved in terms of intron/exon structure and chromosomal localization. Hu-mda-7 encompasses seven exons and six introns and encodes a protein with a predicted size of 23.8 kDa, consisting of 206 amino acids. Hu-mda-7 mRNA is stably expressed in the thymus, spleen and peripheral blood leukocytes. De novo mda-7 mRNA expression is also detected in human melanocytes and expression is inducible in cells of melanocyte/melanoma lineage and in certain normal and cancer cell types following treatment with a combination of IFN-beta plus MEZ. Mda-7 expression is also induced during megakaryocyte differentiation induced in human hematopoietic cells by treatment with TPA (12-O-tetradecanoyl phorbol-13-acetate). In contrast, de novo expression of mda-7 is not detected nor is it inducible by IFN-beta+MEZ in a spectrum of additional normal and cancer cells. No correlation was observed between induction of mda-7 mRNA expression and growth suppression following treatment with IFN-beta+MEZ and induction of endogenous mda-7 mRNA by combination treatment did not result in significant intracellular MDA-7 protein. Radiation hybrid mapping assigned the mda-7 gene to human chromosome 1q, at 1q 32.2 to 1q41, an area containing a cluster of genes associated with the IL-10 family of cytokines. Mda-7 represents a differentiation, growth and apoptosis associated gene with potential utility for the gene-based therapy of diverse human cancers.

The role of the immune system in conjunctival wound healing after glaucoma surgery

The immune system has a fundamental role in the development and regulation of ocular healing, which plays an important role in the pathogenesis of most blinding diseases. This review discusses the mechanisms of normal wound healing, describing the animal and fetal wound healing models used to provide further insight into normal wound repair. In particular, conjunctival wound repair after glaucoma filtration surgery will be used to illustrate the contributions that the different components of the immune system make to the healing process. The potential role of macrophages, the possible regulatory effect of lymphocytes, and the important role of growth factors and cytokines in the wound healing reaction are discussed. The significance of the immune system in the pathogenesis of aggressive conjunctival scarring is addressed, particularly assessing the predisposing factors, including drugs, age, and ethnicity. The rationale behind the pharmacological agents currently used to modulate the wound healing response and the effects these drugs have on the function of the immune system are described. Finally, potential new therapeutic approaches to regulating the wound healing response are reported.