Behavior Of Lens Epithelial Cells Research Articles

Research Progress Concerning a Novel Intraocular Lens for the Prevention of Posterior Capsular Opacification.

Posterior capsular opacification (PCO) is the most common complication resulting from cataract surgery and limits the long-term postoperative visual outcome. Using Nd:YAG laser-assisted posterior capsulotomy for the clinical treatment of symptomatic PCO increases the risks of complications, such as glaucoma, retinal diseases, uveitis, and intraocular lens (IOL) pitting. Therefore, finding how to prevent PCO development is the subject of active investigations. As a replacement organ, the IOL is implanted into the lens capsule after cataract surgery, but it is also associated with the occurrence of PCO. Using IOL as a medium for PCO prophylaxis is a more facile and efficient method that has demonstrated various clinical application prospects. Thus, scientists have conducted a lot of research on new intraocular lens fabrication methods, such as optimizing IOL materials and design, and IOL surface modification (including plasma/ultraviolet/ozone treatment, chemical grafting, drug loading, coating modification, and layer-by-layer self-assembly methods). This paper summarizes the research progress for different types of intraocular lenses prepared by different surface modifications, including anti-biofouling IOLs, enhanced-adhesion IOLs, micro-patterned IOLs, photothermal IOLs, photodynamic IOLs, and drug-loading IOLs. These modified intraocular lenses inhibit PCO development by reducing the residual intraoperative lens epithelial cells or by regulating the cellular behavior of lens epithelial cells. In the future, more works are needed to improve the biosecurity and therapeutic efficacy of these modified IOLs.

IGF-1 Promotes Epithelial-Mesenchymal Transition of Lens Epithelial Cells That Is Conferred by miR-3666 Loss.

The abnormal proliferation, migration, and epithelial-mesenchymal transformation (EMT) of lens epithelial cells (LECs) are the main reasons for vision loss caused by posterior capsular opacification (PCO) after cataract surgery. Insulin-like growth factor-1 (IGF-1) was found to be associated with the pathogenesis of cataracts, but its biological role in PCO is poorly understood. In the present study, IGF-1 overexpression facilitated the proliferation, migration, and EMT, whereas knockdown of IGF-1 markedly suppressed the proliferation, migration, and TGF-β2-induced EMT of LECs. Additionally, to evaluate valuable microRNAs (miRNAs) which target IGF-1 to modulate LEC-EMT, we predicted miR-3666 might regulate IGF-1 by binding its 3'UTR according to the bioinformatics database. Furthermore, we verified that miR-3666 directly targeted IGF-1 by luciferase reporter assay. By using miR-3666 mimics, cell proliferation, migration, and invasion were suppressed, while being enhanced by the reduction of miR-3666. Knockout of IGF1 reverses the effect of the miR-3666 inhibitor on the malignant behavior of LECs. These results indicate the role of miR-3666/IGF-1 in LEC-EMT that offers new strategies for the therapy and prevention of PCO.

Lysyl hydroxylase 3 is required for normal lens capsule formation and maintenance of lens epithelium integrity and fate

Lens abnormalities are a major cause of reduced vision and blindness. One mechanism that can lead to reduced lens transparency, i.e. cataract, is abnormal behavior of lens epithelial cells (LECs), the precursors of the transparent lens fiber cells. Here we describe a zebrafish mutation causing the embryonic lens epithelium to generate cellular masses comprising partially differentiated lens fiber cells. We identify the mutant gene as plod3, which encodes for Lysyl hydroxylase 3 (Lh3), an enzyme essential for modification of collagens, including Collagen IV, a main component of the lens capsule. We show that plod3-deficient lenses have abnormal lens epithelium from an early developmental stage, as well as abnormal lens capsules. Subsequently, upregulation of TGFβ signaling takes place, which drives the formation of lens epithelial cellular masses. We identify a similar phenotype in Collagen IVα5-deficient embryos, suggesting a key role for the defective lens capsule in the pathogenesis. We propose that plod3 and col4a5 mutant zebrafish can serve as useful models for better understanding the biology of LECs during embryonic development and in formation of lens epithelium-derived cataract.

Effects of activation of Src-family tyrosine kinases on human LECs apoptosis and EMT under the high glucose environment

Background Diabetic cataract is one of the major ocular complications in diabetes mellitus, including cortical cataract, nuclear cataract, subcapsular cataract and mixed cataract, and different cataractogenesis may be associated with lens epithelial cells (LECs). Subcapsular cataract is one of diabetic cataracts.Studying the biological behavior of LECs in subcapsular cataract is crucial for prevention and treatment. Objective This study was to investigate the effects of Src-family tyrosine kinases (SFKs) on apoptosis and epithelial-mesenchymal transition (EMT) of human LECs cultured by high glucose. Methods Human LECs (HLE-B3) were cultured for 24 hours with DMEM containing 5.5 mmol/L glucose (normal control group), DMEM containing 35.5 mmol/L glucose (high glucose group) and DMEM containing 35.5 mmol/L glucose + 10 μmol/L PP1, a specific inhibitor of SFKs (PP1 group). In 3, 6, 12 and 24 hours after culture, the apoptosis of human LECs was detected by flow cytometry assay; morphological change of human LECs was observed under the inverted microscope, and the expressions of the markers of EMT, E-cadherin and α-smooth muscle actin (α-SMA), in the cells were detected by immnofluorescence staining.In addition, the alternations of p-Src418 (active c-Src), bcl-xl, survivin, caspase-3, E-cadherin and α-SMA proteins were assayed by Western blot analysis. Results An elevated expression level of p-Src418 was found in LECs in the high glucose group and peaked 6 hours after cultured.The expressions of p-Src418 (grey levels) were 0.125±0.036 in the high glucose group, and which was significantly higher than 0.042±0.011 in the normal control group and 0.035±0.018 in the PP1 group, respectively (both at P 0.05). The apoptotic rates of human LECs were(6.433±2.084)%, (10.333±2.610)% and (8.033±2.967)% in the PP1 group, which were higher than (3.233±1.320)%, (3.533±1.159)%, (5.733±0.230)% in the high glucose group and (3.133±1.170)%, (2.833±0.751)%, (3.333±1.201)% in the normal control group (all at P 0.05). In 6 hours and 12 hours after cell culture, the expression levels of bcl-xl and survivin (grey values) in human LECs were significantly declined, but the expression of caspase-3 was increased in the PP1 group compared with the the high glucose group and the normal control group (all at P<0.05). The LECs showed slender in shape 24 hours after culture in the high glucose group, but the cell shape was close to the normal in the PP1 group.Western blot and immunofluorescence assay revealed that the expression of E-cadherin in human LECs was significantly reduced and that of α-SMA was significantly increased 6 hours after culture in the high glucose group compared with the PP1 group and the normal control group (all at P<0.05). Conclusions High glucose activates c-Src kinase of LECs in high glucose environment and therefore induces EMT and inhibits apoptosis.However, PP1 impedes the biological process of EMT and apoptosis of LECs to maintain the epithelial characteristics even under the stress of high glucose. Key words: Glucose; Human; Epithelial cell, Lens; Apoptosis; Src-family tyrosine kinases; Epithelial-mesenchymal transition; Signaling pathway

Changes of protein kinase regulatory pathway in inhibition of curcumin on human lens epithelial cells proliferation

Background Our previous study showed that curcumin suppresses the proliferation of human lens epithelial cells (LECs) in vitro and has an influence on the signal transduction of cyclic adenosine monophosphate (cAMP) and cyclic guanosinc monophosphate (cGMP). Actually, the regulation for biological behavior of LECs in vivo is complex. Objective This study was to investigate the changes of signal transduction of protein kinase (PK) in inhibition of curcumin on human LECs proliferation. Methods HLE-B3 was cultured and then divided into the blank control group, recombinant human basic fibroblast growth factor (rhbFGF) group and rhbFGF+ curcumin group.rhbFGF of 10 ng/ml was added in the medium in the rhbFGF group, and 20 mg/L curcumin was added into rhbFGF-induced cell medium for 24 hours in the rhbFGF+ curcumin group.The expression rates of PKA, PKC, PKG and calmodulin (CaM) in the cells were assayed using flow cytometry. Results The expression rates of PKA protein were (46.847±1.673)%, (33.250±2.242)% and (71.645±2.432)% in the blank control group, rhbFGF group and the rhbFGF+ curcumin group, respectively, and the expression rate of PKA protein was significantly reduced in the rhbFGF group compared with the blank control group (t=11.904, P<0.01), but the expression rate of PKA protein in the rhbFGF+ curcumin group was significnatly higher than that in the rhbFGF group (t=28.430, P<0.01). In the blank control group, rhbFGF group and the rhbFGF+ curcumin group, the expression rates of PKC protein in the cells were (35.575±1.937)%, (50.652±2.068)% and (27.662±4.481)%, those of PKG protein were (63.838±0.486)%, (86.562±1.325)% and (40.733±2.175)%, while those of CaM protein were (67.408±1.391)%, (83.887±3.499)% and (53.785±1.942)%, the expression rates of PKC, PKG and CaM were significantly lower in the rhbFGF group in comparison with the blank control group (all at P<0.01), and those in the rhbFGF+ curcumin group were significantly declined in comparison with the rhbFGF group (all at P<0.01). Conclusions Suppression of curcumin on HLE-B3 proliferation probably is associated with the up-regulation of PKA expression and down-regulation of PKC, PKG and CaM expression in the cells. Key words: Curcumin; Protein kinase; Signal transduction; Lens epithelial cells

Altered mechanical behavior and properties of the human anterior lens capsule after cataract surgery

Several studies have quantified the mechanics of the normal lens capsule, motivated in large part by the need to understand better the mechanism of accommodation. In addition to this principal physiologic function, the lens capsule also plays a significant clinical role by housing the prosthetic lens implanted during cataract surgery. This procedure alters dramatically the mechanical environment of the capsule, which may modulate the errant behavior of lens epithelial cells that leads to capsular contraction and deposition of non-native matrix proteins. Although much is known about histological alterations within the post-surgical capsule, little is known about the altered mechanics. We performed uniaxial mechanical tests on normal and post-surgical human anterior lens capsules and found, for the first time, that cataract surgery leads to a significant stiffening of the capsule nearest the capsulorhexis edge. These data promise to be important for developing predictive tools capable of elucidating interactions between the post-surgical capsule and implant.

Growth factor deposition in anterior subcapsular cataract

To characterize immunohistochemically the distribution of growth factors and extracellular matrix (ECM) components in an anterior subcapsular cataract (ASC) and to determine the role of growth factors in the development of ASC. Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan. During cataract surgery in 22 patients, anterior capsules with an ASC were obtained. Sections of each specimen were immunostained with a panel of antibodies against ECM components, growth factors, cytoskeletal components, and signal transduction-related molecules. Collagen types I, V, and VI; fibronectin; fibrillin-1; and latent transforming growth factor beta binding protein-1 (LTBP-1) were localized to the ECM in ASC tissues. Collagen IV was localized to the ECM and the capsule. Lens epithelial cells (LECs) were positive for alpha-smooth muscle actin (alphaSMA). Lens epithelial cells and ECM stained for transforming growth factor beta2 (TGFbeta2) and TGFbeta3 in all samples, but TGFbeta1 latency-associated peptide (TGFbeta1-LAP) were detected in some samples. Fibroblast growth factor-2 (FGF-2) and hepatocyte growth factor-alpha (HGF-alpha) were localized to the ECM. Lens epithelial cells with nuclear staining for Erk-1, the mitogen-activated protein kinase (MAP kinase) cascade-related molecule, and Smad3, 1 of the Smad family members involving TGFbeta signaling, were detected. Matrix components (ie, collagen types, fibronectin, fibrillin-1), as well as growth factors such as TGFbeta1-LAP, TGFbeta2, TGFbeta3, FGF-2, and HGF-alpha, were detected in ASC. Fibrillin-1 might serve as a repository for TGFbetas. These growth factors may modulate the phenotypic alteration and behavior of LECs. The MAP kinase cascade and TGFbeta signaling are both activated in LECs in ASC.

Lens development: II. The differentiation of embryonic chick lens epithelial cells in vitro and in vivo

The behavior of lens epithelial cells from six-day chick embryos was studied in three different experimental situations: ( a) explantation into several different fluid culture media, ( b) explantation followed by reimplanlation into lensectomized embryonic eyes, and ( c) explantation followed by reimplantation into the embryonic coelomic cavity. Specimens were examined histologically, and the total volume of the lens material of each specimen was determined from the planimetry of serial sections. The results were interpreted as follows: 1. 1. With a small amount of protein supplement in the culture medium, embryonic lens epithelial cells are capable of a limited amount of independent cytodifferentiation. Without protein supplement they fail to undergo any fiber formation. 2. 2. When returned to the eye environment, cultured epithelial explants will respond with a resumption of growth, with further cellular differentiation, and with at least some of the morphogenetic changes necessary to form a lens. The embryonic coelom will not support these responses. 3. 3. The initiation of the formation of lens fibers is not sufficient for their complete autonomous maturation. 4. 4. The internal architecture of the developing lens is not the only determinant of its overall shape.