Transition Of Lens Epithelial Cells Research Articles

Long Noncoding RNA MALAT1 Acts as a Competing Endogenous RNA to Regulate TGF-β2 Induced Epithelial-Mesenchymal Transition of Lens Epithelial Cells by a MicroRNA-26a-Dependent Mechanism.

The aim of the present study was to characterize whether the long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1)/miR-26a/Smad4 axis is involved in epithelial–mesenchymal transition (EMT) of lens epithelial cells (LECs). Primary human LECs were separated and cultured. Microarray analysis showed that a total of 568 lncRNAs are differentially expressed in primary HLECs in the presence of TGF-β2 and MALAT1 is mostly significantly dysregulated lncRNAs, which is increased by nearly 17-fold. In addition, upregulation of MALAT1 and downregulation of miR-26a were detected in human posterior capsule opacification (PCO) attached LECs and the LECs obtained from patients with anterior polar cataracts by quantitative RT-PCR (qRT-PCR). Next, our results showed that TGF-β2 induces overexpression of EMT markers in primary HLECs via a MALAT1-dependent mechanism. The mechanism is that MALAT1 negatively regulates miR-26a and miR-26a directly targets Smad4 by luciferase reporter assays and RNA-binding protein immunoprecipitation assay. In summary, TGF-β2 induces MALAT1 overexpression, which in turn MALAT1 acts as a ceRNA targeting Smad4 by binding miR-26a and promotes the progression of EMT of LECs.

Regulation of transforming growth factor β-mediated epithelial-mesenchymal transition of lens epithelial cells by c-Src kinase under high glucose conditions.

Recent studies have reported that high glucose (HG) conditions may contribute to the acceleration of renal cell apoptosis and renal fibrosis by inducing epithelial-mesenchymal transition (EMT) of tubular epithelial cells, in which c-Src kinase and transforming growth factor (TGF)-β are key modulators. In the present study, the roles of c-Src kinase and TGF-β in EMT of lens epithelial cells (LECs) under HG conditions were investigated. Results indicated human lens epithelial B3 (HLE-B3) cells under HG conditions exhibited significantly increased protein expression levels of phosphorylated c-Src (p-Src418) (P<0.05) and secreted a significantly increased amount of TGF-β compared with HLE-B3 cells under normal glucose conditions (P<0.05). Notably the c-Src inhibitor PP1 and the activin receptor-like kinase 5 (ALK5) inhibitor SB431542 suppressed EMT of HLE-B3 cells. Results indicated that PP1 significantly inhibited the activities of c-Src and ALK5 and the secretion of TGF-β, whereas SB431542 only significantly downregulated the protein expression levels and secretion of TGF-β (P<0.05). Following c-Src knockdown, the protein expression levels of p-Src418, ALK5 and TGF-β were significantly decreased, the secretion of TGF-β was significantly suppressed (both P<0.05) and EMT was decreased in HLE-B3 cells. These results suggest that c-Src and TGF-β may promote EMT of LECs under HG conditions, with c-Src as the upstream regulatory molecule. Thus, the signal axis of c-Src/TGF-β in EMT of LECs may be a potential novel therapeutic target for the prevention of diabetic subcapsular cataract.

EGF-Mediated Overexpression of Myc Attenuates miR-26b by Recruiting HDAC3 to Induce Epithelial-Mesenchymal Transition of Lens Epithelial Cells.

The previous study has demonstrated that epidermal growth factor (EGF) and EGF receptor (EGFR) signaling plays a critical role in the development of posterior capsule opacification (PCO) through regulating lens epithelial cells (LECs) proliferation. Recent studies have suggested that the residual LECs undergo proliferation and migration, and epithelial-mesenchymal transition (EMT) is the important cause of PCO formation after cataract surgery. EMT of LECs is considered to be playing a central role in the pathogenesis of PCO. In the present study, we investigated whether and how EGF may regulate EMT of LECs. First, we demonstrated that EGF and EGFR signaling induces Myc overexpression in primary human lens epithelial cells (HLECs). In turn, Myc overexpression could inhibit miR-26b by recruitment of HDAC3. Consequently, the downregulated expression of miR-26b increased the expression of EZH2 in primary HLECs. Mechanistically, miR-26b directly controls EZH2 expression by targeting its 3′-UTR in HLECs by luciferase reporter assays. Finally, we demonstrated that EGF induces the expression of EMT markers in primary HLECs via a miR-26b-dependent mechanism. In summary, EGF activated Myc and Myc overexpression inhibited miR-26b by recruitment of HDAC3, which in turn induced the expression of EZH2 and promoted the progression of EMT in HLECs.

Matrix-bound AGEs enhance TGFβ2-mediated mesenchymal transition of lens epithelial cells via the noncanonical pathway: implications for secondary cataract formation.

Advanced glycation end products (AGEs) are post-translational modifications formed from the reaction of reactive carbonyl compounds with amino groups in proteins. Our laboratory has previously shown that AGEs in extracellular matrix (ECM) proteins promote TGFβ2 (transforming growth factor-beta 2)-mediated epithelial-to-mesenchymal transition (EMT) of lens epithelial cells (LECs), which could play a role in fibrosis associated with posterior capsule opacification. We have also shown that αB-crystallin plays an important role in TGFβ2-mediated EMT of LECs. Here, we investigated the signaling mechanisms by which ECM-AGEs enhance TGFβ2-mediated EMT in LECs. We found that in LECs cultured on AGE-modified basement protein extract (AGE-BME), TGFβ2 treatment up-regulated the mesenchymal markers α-SMA (α-smooth muscle actin) and αB-crystallin and down-regulated the epithelial marker E-cadherin more than LECs cultured on unmodified BME and treated with TGFβ2. Using a Multiplex Assay, we found that AGE-BME significantly up-regulated the noncanonical pathway by promoting phosphorylation of ERK (extracellular signal-regulated kinases), AKT, and p38 MAPK (mitogen-activated protein kinases) during TGFβ2-mediated EMT. This EMT response was strongly suppressed by inhibition of AKT and p38 MAPK phosphorylation. The AKT inhibitor LY294002 also suppressed TGFβ2-induced up-regulation of nuclear Snail and reduced phosphorylation of GSK3β. Inhibition of Snail expression suppressed TGFβ2-mediated α-SMA expression. αB-Crystallin was up-regulated in an AKT-dependent manner during AGE-BME/TGFβ2-mediated EMT in LECs. The absence of αB-crystallin in LECs suppressed TGFβ2-induced GSK3β phosphorylation, resulting in lower Snail levels. Taken together, these results show that ECM-AGEs enhance the TGFβ2-mediated EMT response through activation of the AKT/Snail pathway, in which αB-crystallin plays an important role as a linker between the TGFβ2 and AGE-mediated signaling pathways.

MicroRNA-486-5p suppresses TGF-β2-induced proliferation, invasion and epithelial-mesenchymal transition of lens epithelial cells by targeting Smad2.

The pathological development of lens epithelial cells (LECs) leads to posterior capsular opacification (PCO). This study was undertaken to investigate the effects of microRNA-486-5p (miR-486-5p) on TGF-β2-induced proliferation, invasion and epithelial-mesenchymal transition (EMT) in the lens epithelial cell line SRA01/04, and to explore the underlying molecular mechanisms. The expression of miR-486-5p in TGF-β2-induced SRA01/04 cells was down-regulated, and the expression of Smad2, p-Smad2 and p-Smad3 was up-regulated. A dual-luciferase reporter assay revealed that miR-486-5p directly targets the 30'-UTR of Smad2. MiR-486-5p mimic transfection markedly down-regulated the expression levels of Smad2, thus inhibiting the expression of p-Smad2 and p-Smad3. MiR-486-5p overexpression in SRA01/04 cells markedly suppressed TGF-β2-induced proliferation and invasion, inhibited protein expression of CDK2 and CDK4, down-regulated fibronectin, α-SMA and vimentin and up-regulated E-cadherin; these effects were partly reversed by Smad2 overexpression. In short, these data show that miR-486-5p overexpression can inhibit TGF-β2-induced proliferation, invasion and EMT in SRA01/04 cells by repressing Smad2/Smad3 signalling, implying that miR-486-5p may be an effective target to interfere in the progression of PCO.

Reduced Glutathione Level Promotes Epithelial-Mesenchymal Transition in Lens Epithelial Cells via a Wnt/β-Catenin–Mediated Pathway: Relevance for Cataract Therapy

The epithelial-mesenchymal transition (EMT) process plays a pivotal role in the pathogenesis of posterior capsular opacification because of remnant lens epithelial cell proliferation, migration, and transformation after cataract surgery. The latter, we hypothesize, may result in posterior capsule wrinkling and opacification because of a profound change in the lens growth environment via a 1000-fold reduction of extracellular glutathione (GSH) levels. To test this hypothesis, we investigated the EMT process in cell culture and GSH biosynthesis deficiency mouse models. Our data indicate a dramatic increase of pro-EMT markers, such as type I collagen, α-smooth muscle actin, vimentin, and fibronectin, under conditions of lens GSH depletion. Further study suggests that decreased GSH triggers the Wnt/β-catenin signal transduction pathway, independent of transforming growth factor-β. Equally important, the antioxidants N-acetyl cysteine and GSH ethyl ester could significantly attenuate the EMT signaling stimulated by decreased GSH levels. These findings were further confirmed by mock cataract surgery in both gamma glutamyl-cysteine ligase, catalytic subunit, and gamma glutamyl-cysteine ligase, modifier subunit, knockout mouse models. Remarkably, increased EMT marker expression, β-catenin activation, and translocation into the nucleus were found in both knockout mice compared with the wild type, and such increased expression could be significantly attenuated by N-acetyl cysteine or GSH ethyl ester treatment. This study, for the first time we believe, links oxidative stress to lens fibrosis and posterior capsular opacification formation via EMT-mediated mechanisms.

Influence of aldose reductase on epithelial-to-mesenchymal transition signaling in lens epithelial cells

Cataract is the most frequent cause of blindness worldwide and is treated by surgical removal of the opaque lens to restore the light path to the retina. While cataract surgery is a safe procedure, some patients develop a complication of the surgery involving opacification and wrinkling of the posterior lens capsule. This process, called posterior capsule opacification (PCO), requires a second clinical treatment that can in turn lead to additional complications. Prevention of PCO is a current unmet need in the vision care enterprise. The pathogenesis of PCO involves the transition of lens epithelial cells to a mesenchymal phenotype, designated epithelial-to-mesenchymal transition (EMT). Our previous studies showed that transgenic mice designed for overexpression of human aldose reductase developed lens defects reminiscent of PCO. In the current study, we evaluated the impact of aldose reductase (AR) on expression of expression of EMT markers in the lens. Primary lens epithelial cells from AR-transgenic mice showed downregulated expression of Foxe3 and Pax6 and increased expression of α-SMA, fibronectin and snail, a pattern of gene expression typical of cells undergoing EMT. A role for AR in these changes was further confirmed when we observed that they could be normalized by treatment of cells with Sorbinil, an AR inhibitor. Smad-dependent and Smad-independent pathways are known to contribute to EMT. Interestingly, AR overexpression induced ERK but not Smad-2 activation. These results suggest that elevation of AR may lead to activation of ERK signaling and thus play a role in TGF-β/Smad independent induction of EMT in lens epithelial cells.

β-Catenin/CBP-Dependent Signaling Regulates TGF-β-Induced Epithelial to Mesenchymal Transition of Lens Epithelial Cells.

PurposeTransforming growth factor-β–induced epithelial–mesenchymal transition (EMT) is one of the main causes of posterior capsular opacification (PCO) or secondary cataract; however, the signaling events involved in TGF-β–induced PCO have not been fully characterized. Here, we focus on examining the role of β-catenin/cyclic AMP response element–binding protein (CREB)-binding protein (CBP) and β-catenin/T-cell factor (TCF)-dependent signaling in regulating cytoskeletal dynamics during TGF-β–induced EMT in lens epithelial explants.MethodsRat lens epithelial explants were cultured in medium M199 in the absence of serum. Explants were treated with TGF-β2 in the presence or absence of the β-catenin/CBP interaction inhibitor, ICG-001, or the β-catenin/TCF interaction inhibitor, PNU-74654. Western blot and immunofluorescence experiments were carried out and analyzed.ResultsAn increase in the expression of fascin, an actin-bundling protein, was observed in the lens explants upon stimulation with TGF-β, and colocalized with F-actin filaments. Inhibition of β-catenin/CBP interactions, but not β-catenin/TCF interactions, led to a decrease in TGF-β–induced fascin and stress fiber formation, as well as a decrease in the expression of known markers of EMT, α-smooth muscle actin (α-SMA) and matrix metalloproteinase 9 (MMP9). In addition, inhibition of β-catenin/CBP–dependent signaling also prevented TGF-β–induced downregulation of epithelial cadherin (E-cadherin) in lens explants.ConclusionsWe show that β-catenin/CBP–dependent signaling regulates fascin, MMP9, and α-SMA expression during TGF-β–induced EMT. We demonstrate that β-catenin/CBP–dependent signaling is crucial for TGF-β–induced EMT in the lens.

αB-crystallin is essential for the TGF-β2-mediated epithelial to mesenchymal transition of lens epithelial cells.

Transforming growth factor (TGF)-β2-mediated pathways play a major role in the epithelial to mesenchymal transition (EMT) of lens epithelial cells (LECs) during secondary cataract formation, which is also known as posterior capsule opacification (PCO). Although αB-crystallin is a major protein in LEC, its role in the EMT remains unknown. In a human LEC line (FHL124), TGF-β2 treatment resulted in changes in the EMT-associated proteins at the mRNA and protein levels. This was associated with nuclear localization of αB-crystallin, phosphorylated Smad2 (pSmad2) (S245/250/255), pSmad3 (S423/425), Smad4 and Snail and the binding of αB-crystallin to these transcription factors, all of which were reduced by the down-regulation of αB-crystallin. Expression of the functionally defective R120G mutant of αB-crystallin reduced TGF-β2-induced EMT in LECs of αB-crystallin knockout (KO) mice. Treatment of bovine lens epithelial explants and mouse LEC with TGF-β2 resulted in changes in the EMT-associated proteins at the mRNA and protein levels. This was accompanied by increase in phosphorylation of p44/42 mitogen-activated protein kinases (MAPK) (T202/Y204), p38 MAPK (T180/Y182), protein kinase B (Akt) (S473) and Smad2 when compared with untreated cells. These changes were significantly reduced in αB-crystallin depleted or knocked out LEC. The removal of the fibre cell mass from the lens of wild-type (WT) mice resulted in the up-regulation of EMT-associated genes in the capsule-adherent epithelial cells, which was reduced in the αB-crystallin KO mice. Together, our data show that αB-crystallin plays a central role in the TGF-β2-induced EMT of LEC. αB-Crystallin could be targeted to prevent PCO and pathological fibrosis in other tissues.

Bit1—a potential positive regulator of epithelial–mesenchymal transition in lens epithelial cells

Posterior capsule opacification (PCO) is a common postoperative complication of cataract surgery. Epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is an important initial step of PCO pathogenesis. We have previously shown that Bit1 expresses in rat LECs. In this study, we aim to investigate the role of Bit1 in the EMT of human LECs. The expression of Bit1 was firstly detected in human PCO-attached LECs and human lens cell line SRA01/04 by real-time PCR and immunofluorescence staining. The proliferation and migration of Bit1 knockdown SRA01/04 cells were evaluated by cell counting, wound-healing assay, and transwell migration assay. The EMT of LECs was triggered by TGF-β2, and then the effect of Bit1 on EMT with a key biomarker of α-smooth muscle actin (α-SMA) was analyzed by siRNA knockdown assay, and the reversal of EMT was validated by real-time PCR and western blot. Bit1 was obviously augmented in LECs derived from PCO tissues and Bit1 expressed with high levels in the cytoplasm of cultured SRA01/04 cells. Cell proliferation, invasion, and migration, as well as α-SMA expression, were significantly decreased in Bit1 knockdown SRA01/04 cells. While TGF-β2 elevated Bit1 and α-SMA expression levels in a dose-dependent manner, with peak levels at 10ng/ml of TGF-β2 treatment, suppression of Bit1 in SRA01/04 cells reversed the EMT process. TGF-β2 induced elevation of α-SMA expression level, as well as migration, and invasion abilities were all suppressed by Bit1 deficiency. These findings reveal that Bit1 promotes TGF-β2 induced α-SMA expression and acts as an positive regulator of EMT. Suppressing Bit1 inhibits the proliferation, migration, and EMT of LECs. Bit1 may be a potential novel therapeutic target for the prevention and treatment of PCO.

RhoA/ROCK signaling regulates TGFβ-induced epithelial-mesenchymal transition of lens epithelial cells through MRTF-A.

Transforming growth factor (TGF)-β-induced epithelial-mesenchymal transition (EMT) leads to the formation of ocular fibrotic pathologies, such as anterior subcapsular cataract and posterior capsule opacification. Remodeling of the actin cytoskeleton, mediated by the Rho family of GTPases, plays a key role in EMT, however, how actin dynamics affect downstream markers of EMT has not been fully determined. Our previous work suggests that myocardin related transcription factor A (MRTF-A), an actin-binding protein, might be an important mediator of TGFβ-induced EMT in lens epithelial cells. The aim of the current study was to determine the requirement of RhoA/ROCK signaling in mediating TGFβ-induced nuclear accumulation of MRTF-A, and ultimate expression of α-smooth muscle actin (αSMA), a marker of a contractile, myofibroblast phenotype. Using rat lens epithelial explants, we demonstrate that ROCK inhibition using Y-27632 prevents TGFβ-induced nuclear accumulation of MRTF-A, E-cadherin/β-catenin complex disassembly, and αSMA expression. Using a novel inhibitor specifically targeting MRTF-A signaling, CCG-203971, we further demonstrate the requirement of MRTF-A nuclear localization and activity in the induction of αSMA expression. Overall, our findings suggest that TGFβ-induced cytoskeletal reorganization through RhoA/ROCK/MRTF-A signaling is critical to EMT of lens epithelial cells.

Association of histone acetylation at the ACTA2 promoter region with epithelial mesenchymal transition of lens epithelial cells.

Epithelial mesenchymal transition (EMT) plays a central role in the development of fibrotic complications of the lens. The current study is designed to check whether EMT of lens epithelial cells (LECs) is regulated by epigenetic modifications and to evaluate the effect of Trichostatin-A (TSA) on the transforming growth factor-β (TGF-β)-induced EMT. Fetal human LECs (FHL124) were treated with TGF-β2 in the presence or absence of TSA. Levels of mRNA, protein, as well as localization of α-smooth muscle actin (αSMA) were studied along with migration of LECs. Acetylation of histone H4 was analyzed and chromatin immunoprecipitation (ChIP) was carried out to study the level of acetylated histone H4 at the promoter of αSMA gene (ACTA2). Student's t-test was used for statistical analysis. TGF-β2 treatment resulted in myofibroblast-like changes and increased migratory capacity of FHL124. Protein and mRNA expression of αSMA increased, and immunofluorescence revealed presence of extensive stress fibers. TSA treatment preserved epithelial morphology, retarded cell migration, and abrogated an increase in αSMA levels. TSA led to the accumulation of acetylated histone H4 that was reduced on TGF-β2 treatment. However, increased level of histone H4 acetylation was found at the ACTA2 promoter region during TGF-β treatment. The increased level of αSMA, a hallmark of EMT in LECs, is associated with increased level of histone H4 acetylation at its promoter region, and TSA helps in suppressing EMT by epigenetically reducing this level. TSA thus shows promising potential in management of fibrotic conditions of the lens.

MiRNA-26b inhibits the proliferation, migration, and epithelial-mesenchymal transition of lens epithelial cells.

MicroRNAs (miRNAs) are a class of small endogenous gene regulators that play important roles in various developmental and pathological processes. However, little is known about the precise identity and functions of miR-26b in posterior capsule opacification (PCO). In this study, we report that the expression of miR-26b is decreased in human PCO-attached lens epithelial cells (LECs) and SRA01/04 cells in the presence of TGF-β2. Overexpression of miR-26b inhibited the proliferation of LECs based on MTT assays and BrdU incorporation assays. In addition, the overexpression of miR-26b inhibited the migration ability of LECs, as shown by wound-healing and transwell migration assays. The overexpression of miR-26b increased the level of the lens epithelial marker E-cadherin and reduced the levels of mesenchymal-related proteins, such as fibronectin, a-SMA, and type I collagen, in SRA01/04 cells in the presence of TGF-β2. Furthermore, the upregulation of E-cadherin and downregulation of mesenchymal-related proteins were induced in human PCO-attached LECs transfected with miR-26b mimics. We further demonstrated that Smad4 and COX-2 are targets of miR-26b in LECs using luciferase reporter assays. These data reveal that miR-26b can inhibit the proliferation, migration, and EMT of lens epithelial cells, and restoration of miRNA-26b may be a potential, novel therapeutic target for the prevention and treatment of posterior capsule opacification.

Elevated tropomyosin expression is associated with epithelial–mesenchymal transition of lens epithelial cells

Injury to lens epithelial cells (LECs) leads to epithelial–mesenchymal transition (EMT) with resultant fibrosis. The tropomyosin (Tpm) family of cytoskeleton proteins is involved in regulating and stabilizing actin microfilaments. Aberrant expression of Tpms leads to abnormal morphological changes with disintegration of epithelial integrity. The EMT of LECs has been proposed as a major cause of posterior capsule opacification (PCO) after cataract surgery. Using in vivo rodent PCO and human cataractous LECs, we demonstrated that the aberrant expression of rat Tpm and human Tpm1α/2β suggested their association in remodelling of the actin cytoskeleton during EMT of LECs. Expression analysis from abnormally growing LECs after lens extraction revealed elevated expression of α-smooth muscle actin (α-SMA), a marker for EMT. Importantly, these cells displayed increased expression of Tpm1α/2β following EMT/PCO formation. Expression of Tpm1α/2β was up-regulated in LECs isolated from cataractous lenses of Shumiya Cataract Rats (SCRs), compared with non-cataractous lenses. Also, LECs from human patients with nuclear cataract and anterior subcapsular fibrosis (ASF) displayed significantly increased expression of Tpm2β mRNA, suggesting that similar signalling invokes the expression of these molecules in LECs of cataractous SCR and human lenses. EMT was observed in LECs overexpressed with Tpm1α/2β, as evidenced by increased expression of α-SMA. These conditions were correlated with remodelling of actin filaments, possibly leading to EMT/PCO and ASF. The present findings may help clarify the condition of the actin cytoskeleton during morphogenetic EMT, and may contribute to development of Tpm-based inhibitors for postponing PCO and cataractogenesis.

Rho activation is required for transforming growth factor‐β‐induced epithelial‐mesenchymal transition in lens epithelial cells

Lens epithelial cells undergo epithelial-mesenchymal transition (EMT) after injury as in cataract extraction, leading to fibrosis of the lens capsule. We have recently shown that TGF-beta-induced EMT in lens epithelial cells depends on PI3 kinase/Akt signal pathway. In this report, we suggest Smad3 is necessary for TGF-beta-induced EMT by showing that the expression of dominant-negative Smad3 blocks the expression of alpha-smooth muscle actin (alpha-SMA) and morphological changes. We also show that TGF-beta induces a biphasic change in Rho activity, and that Y27632, a selective inhibitor of Rho effector ROCK, inhibits TGF-beta-induced EMT in vitro and in vivo. We finally show that Smad3 activation and Rho signal activation is independent each other. All of these findings suggest that Rho/ROCK activation together with Smad3 is necessary for TGF-beta-induced EMT in lens epithelial cells.

Matrix Metalloproteinase Inhibitors Suppress Transforming Growth Factor-β-Induced Subcapsular Cataract Formation

The pleotropic morphogen transforming growth factor-beta (TGFbeta) plays an important role in the development of fibrotic pathologies, including anterior subcapsular cataracts (ASCs). ASC formation involves increased proliferation and transition of lens epithelial cells into myofibroblasts, through epithelial-mesenchymal transformation that results in opaque plaques beneath the lens capsule. In this study, we used a previously established TGFbeta-induced rat cataract model to explore the role of matrix metalloproteinases (MMPs) in ASC formation. Treatment of excised rat lenses with TGFbeta resulted in enhanced secretion of MMP-2 and MMP-9. Importantly, co-treatment with two different MMP inhibitors (MMPIs), the broad spectrum inhibitor GM6001 and an MMP-2/9-specific inhibitor, suppressed TGFbeta-induced ASC changes, including the epithelial-mesenchymal transformation of lens epithelial cells. Using an anti-E-cadherin antibody, we revealed that conditioned media from lenses treated with TGFbeta contained a 72-kd E-cadherin fragment, indicative of E-cadherin shedding. This was accompanied by attenuated levels of E-cadherin mRNA. Conditioned media from lenses co-treated with TGFbeta and MMPIs exhibited attenuated levels of the E-cadherin fragment compared with those from TGFbeta-treated lenses. Together, these findings demonstrate that TGFbeta-induced E-cadherin shedding in the lens is mediated by MMPs and that suppression of this phenomenon might explain the mechanism by which MMPIs inhibit ASC plaque formation.

Histology of anterior capsule opacification with a polyHEMA/HOHEXMA hydrophilic hydrogel intraocular lens compared to poly(methyl methacrylate), silicone, and acrylic lenses

Purpose To evaluate the biocompatibility of various materials including a poly(2-hydroxyethyl methacrylate [HEMA])/(6-hydroxyhexyl methacrylate [HOHEXMA]) hydrophilic hydrogel intraocular lens (IOL) (Hydroview®, Bausch & Lomb). Setting Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan. Methods Ten opacified anterior capsules were extracted, including 3 specimens with the Hydroview IOL. They were processed for light and electron microscopy. Immunohistochemistry for α-smooth muscle actin (αSMA) and collagen types was also done to evaluate mesenchymal transition in lens epithelial cells (LECs). Results Anterior capsule opacification (ACO) in the 3 specimens with a polyHEMA/HOHEXMA hydrogel IOL contained more LECs and less extracellular matrix (ECM) than in the specimens with IOLs of other materials. Ultrastructural observation showed a well-organized collagenous ECM in tissues with an IOL of poly(methyl methacrylate), silicone, or soft acrylic material; an immature matrix was seen in specimens with a hydrogel IOL. The αSMA-positive LECs and collagen I and III, both types related to capsular wound healing, were detected in ACO. Conclusions A polyHEMA/HOHEXMA hydrogel IOL facilitated the proliferation of LECs on the anterior capsule compared with other IOLs of other materials but did not completely suppress mesenchymal transition of LECs. Extracellular matrix accumulation appeared immature and less with a polyHEMA/HOHEXMA hydrogel IOL.

Hypophysial hormones and a G1 block in the lens epithelium of the adult frog (Rana pipiens)

Mechanical injury initself may be responsible for the transition of lens epithelial cells from the G0 to the G1 compartment of the cell cycle. This traverse which does not depend on DNA-dependent hypophysial hormones may be in part reversible.