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Judith A Westmays - One of the best experts on this subject based on the ideXlab platform.
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matrix metalloproteinase 9 null mice are resistant to tgf β induced anterior Subcapsular Cataract formation
American Journal of Pathology, 2014Co-Authors: Anna Korol, Dhruva J Dwivedi, G Pino, Jennifer Robertson, Paula Deschamps, Judith A WestmaysAbstract:Epithelial-mesenchymal transition (EMT) is associated with fibrotic diseases in the lens, such as anterior Subcapsular Cataract (ASC) formation. Often mediated by transforming growth factor (TGF)-β, EMT in the lens involves the transformation of lens epithelial cells into a multilayering of myofibroblasts, which manifest as plaques beneath the lens capsule. TGF-β–induced EMT and ASC have been associated with the up-regulation of two matrix metalloproteinases (MMPs): MMP-2 and MMP-9. The current study used MMP-2 and MMP-9 knockout (KO) mice to further determine their unique roles in TGF-β–induced ASC formation. Adenoviral injection of active TGF-β1 into the anterior chamber of all wild-type and MMP-2 KO mice led to the formation of distinct ASC plaques that were positive for α-smooth muscle actin, a marker of EMT. In contrast, only a small proportion of the MMP-9 KO eyes injected with adenovirus-expressing TGF-β1 exhibited ASC plaques. Isolated lens epithelial explants from wild-type and MMP-2 KO mice that were treated with TGF-β exhibited features indicative of EMT, whereas those from MMP-9 KO mice did not acquire a mesenchymal phenotype. MMP-9 KO mice were further bred onto a TGF-β1 transgenic mouse line that exhibits severe ASC formation, but shows a resistance to ASC formation in the absence of MMP-9. These findings suggest that MMP-9 expression is more critical than MMP-2 in mediating TGF-β–induced ASC formation.
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temporal changes in mmp mrna expression in the lens epithelium during anterior Subcapsular Cataract formation
Experimental Eye Research, 2009Co-Authors: Z Nathu, Dhruva J Dwivedi, John R Reddan, Heather Sheardown, Peter J Margetts, Judith A WestmaysAbstract:Abstract Transforming growth factor beta (TGFβ) has been known to play a role in anterior Subcapsular Cataract (ASC) formation and posterior capsule opacification (PCO), both of which are fibrotic pathologies of the lens. Several models have been utilized to study ASC formation, including the TGFβ1 transgenic mouse model and the ex-vivo rat lens model. A distinct characteristic of ASC development within these models includes the formation of isolated fibrotic plaques or opacities which form beneath the lens capsule. A hallmark feature of ASC formation is the epithelial to mesenchymal transition (EMT) of lens epithelial cells (LECs) into myofibroblasts. Recently, the matrix metalloproteinases (MMPs) have been implicated in the formation of these Cataracts through their involvement in EMT. In the present study, we sought to further investigate the role of MMPs in Subcapsular Cataract formation in a time course manner, through the examination of gene expression and morphological changes which occur during this process. RT-QPCR and immunohistochemical analysis was carried out on lenses treated with TGFβ for a period of 2, 4 and 6 days. Laser capture microdissection (LCM) was utilized to specifically isolate cells within the plaque region and cells from the adjacent epithelium in lenses treated for a 6 day period. Multilayering of LECs was observed as early as day 2, which preceded the presence of alpha smooth muscle actin (α-SMA) immunoreactivity that was evident following 4 days of treatment with TGFβ. A slight reduction in E-cadherin mRNA was detected at day 2, although this was not significant until the day 4 time point. Importantly, our results also indicate an early induction of MMP-9 mRNA following 2 days of TGFβ treatment, whereas MMP-2 was found to be upregulated at the later 4 day time point. Further experiments using FHL 124 cells show an induction in MMP-2 protein levels following treatment with recombinant MMP-9. Together these findings suggest an upstream role for MMP-9 in ASC formation.
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lens specific expression of tgf β induces anterior Subcapsular Cataract formation in the absence of smad3
Investigative Ophthalmology & Visual Science, 2006Co-Authors: Alice Banh, Paul A Overbeek, Paula Deschamps, Jack Gauldie, Jacob G Sivak, Judith A WestmaysAbstract:Transforming growth factor (TGF)-β is a secreted polypeptide that is involved in various cellular processes, including cell proliferation, differentiation, apoptosis, migration, and extracellular matrix (ECM) formation.1-5 TGF-β has been shown to promote wound healing by stimulating the production and deposition of ECM, which is essential to normal tissue repair after injury.6 The profibrotic actions of TGF-β have also been implicated in multiple fibrotic diseases, including those of the eye, such as glaucoma and anterior Subcapsular Cataract (ASC).7-10 The ocular lens is a transparent structure that provides part of the refractive power needed to focus images on the retina of the eye. A Cataract involves a reduction in transparency of the lens, which can lead to vision loss. Specifically, ASC can occur after ocular trauma, ocular surgery or in conjunction with diseases such as atopic dermatitis and retinitis pigmentosa.11,12 The development of ASC involves the transformation and proliferation of the anterior epithelial cells of the lens into plaques of large “spindle shaped” cells, or myofibroblasts, through a phenomenon known as epithelial-to-mesenchymal transition (EMT).13-15 The appearance of the myofibroblasts promotes lens capsule wrinkling and an aberrant deposition of extracellular matrix (ECM), both of which are features of ASC.1,7,16,17 Similarly, in secondary Cataract (also known as posterior capsular opacification [PCO]), a complication that develops after Cataract surgery, lens epithelial cells that remain within the capsule are triggered to proliferate and migrate to the posterior lens capsule where they transition into myofibroblasts through EMT.18,19 Under physiological conditions, TGF-β in the lens and ocular media mainly exists in its latent form, whereas biologically active TGF-β has been detected in the ocular media of patients with ASC.20,21 There are three functionally and structurally related species of TGF-β: TGF-β1, -β2, and -β3.22 Studies using in vitro rat lens cultures and lens epithelial explants have shown that all three TGF-β isoforms can induce Cataractous changes similar to those observed in humans. However, TGF-β1 is 10 times less potent than TGF-β2 and -β3.23 The in vivo expression of self-activating TGF-β1 in a transgenic mouse model has been useful for examining the morphologic and molecular changes involved in ASC formation which closely resemble those in humans.1,7,24 However, the TGF-β-mediated signaling pathways regulating fibrosis including those governing ASC formation have not been clearly defined. Smad proteins are intracellular molecules involved in TGF-β signal transduction from the receptors to the target genes in the nucleus.22,25,26 On ligand binding and TGF-β receptor activation, phosphorylation of receptor-regulated Smad2 and -3 occurs, which leads to the formation of hetero-oligomeric complexes with Smad4 (co-Smad).22,25,26 The Smad complexes then translocate into the nucleus, where they regulate target gene expression in collaboration with other coactivators and corepressors. The Smad3-knockout mouse model has been useful in determining TGF-β mediated fibrotic events requiring Smad3 signaling.27-30 An important finding is that ablation of Smad3 in mice prevents the EMT of lens epithelial cells that occurs on injury to the lens capsule,31 suggesting that EMT in the lens may be entirely Smad3 dependent. However, the effect of TGF-β on ASC formation in the absence of Smad3 has not been directly tested. In the present study, we directly determined the requirement for Smad3 in ASC formation using an in vivo transgenic TGF-β1/Smad3 knockout mouse model. Evidence of ASC formation in TGF-β1/Smad3-/- mice and their TGF-β1/Smad wild-type littermates was evaluated histologically and immunohistochemically using the EMT marker α-smooth muscle actin (SMA), as well as fibrotic markers, fibronectin and collagen types I and IV. Formation of ASC in mice was also evaluated by using a quantitative measure of lens optical quality. The results showed that EMT and the formation of ASC plaques occurred in the TGF-β1/Smad3-/- mice, accompanied by a significant decrease in optical quality of the lens. However, the plaques in the TGF-β1/Smad3-/- mice were smaller, contained a greater number of apoptotic cells and substantially less collagen than did their Smad3 heterozygote and wild-type littermates. Together these findings demonstrate that while Smad3 signaling contributes to some aspects of the TGF-β1-induced ASC phenotype, it is not necessary for ASC formation, and additional Smad3-independent pathways are involved in this ocular fibrotic disease.
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matrix metalloproteinase inhibitors suppress transforming growth factor β induced Subcapsular Cataract formation
American Journal of Pathology, 2006Co-Authors: Dhruva J Dwivedi, Z Nathu, Peter J Margetts, G Pino, Alice Banh, Jacob G Sivak, Derek Howchin, Judith A WestmaysAbstract:The pleotropic morphogen transforming growth factor-β (TGFβ) 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 TGFβ-induced rat Cataract model to explore the role of matrix metalloproteinases (MMPs) in ASC formation. Treatment of excised rat lenses with TGFβ 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 TGFβ-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 TGFβ 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 TGFβ and MMPIs exhibited attenuated levels of the E-cadherin fragment compared with those from TGFβ-treated lenses. Together, these findings demonstrate that TGFβ-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.
Jie Jin Wang - One of the best experts on this subject based on the ideXlab platform.
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serum homocysteine vitamin b12 and folate and the prevalence and incidence of posterior Subcapsular Cataract
Investigative Ophthalmology & Visual Science, 2015Co-Authors: Paul Mitchell, Elena Rochtchina, Victoria M. Flood, Robert G. Cumming, Jie Jin WangAbstract:PURPOSE: We assessed associations between serum levels of homocysteine, vitamin B12, and folate, and the prevalence and 5-year incidence of posterior Subcapsular Cataract (PSC) in Blue Mountains Eye Study participants. METHODS: We examined 3508 participants aged 49+ years during 1997 to 2000, including 2334 (75.1% of survivors) original and 1174 (85.2% of those eligible) newly recruited subjects. Five years later (2002-2004), 1952 (76.6% of survivors) original participants were re-examined. Detailed examinations, including lens photographs and fasting blood tests, were conducted at both visits. Logistic regression models estimated odds ratios (OR) and 95% confidence intervals (CI) after multivariable adjustment. RESULTS: In this population, those with PSC were older, less likely to have higher education, and more likely to have diabetes and myopia. The PSC prevalence was 5.7% (150/2644). Higher levels of homocysteine (per SD; OR, 1.17; 95% CI, 1.00-1.37) and lower levels of folate (per SD; OR, 1.24; 95% CI, 0.99-1.56) were associated with prevalent PSC. There was significant interaction (P < 0.05) between vitamin B12 and homocysteine; for B12 ≥125 pmol/L, 28% higher PSC prevalence was associated with homocysteine (per SD; OR, 1.28; 95% CI, 1.09-1.52); however, for B12 <125 pmol/L, nonsignificant lower PSC prevalence was associated with homocysteine (per SD; OR, 0.16; 95% CI, 0.02-1.57). The 5-year PSC incidence was 5.7% (n = 59/1030) with no significant associations with homocysteine, B12, and folate. CONCLUSIONS: Higher serum homocysteine level was associated with PSC prevalence in this population. Vitamin B12 status seemed to modify this association. Lack of longitudinal association could have resulted from insufficient study power.
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Serum homocysteine, vitamin B12, and folate, and the prevalence and incidence of posterior Subcapsular Cataract.
Investigative Ophthalmology & Visual Science, 2014Co-Authors: Paul Mitchell, Elena Rochtchina, Victoria M. Flood, Robert G. Cumming, Jie Jin WangAbstract:PURPOSE: We assessed associations between serum levels of homocysteine, vitamin B12, and folate, and the prevalence and 5-year incidence of posterior Subcapsular Cataract (PSC) in Blue Mountains Eye Study participants. METHODS: We examined 3508 participants aged 49+ years during 1997 to 2000, including 2334 (75.1% of survivors) original and 1174 (85.2% of those eligible) newly recruited subjects. Five years later (2002-2004), 1952 (76.6% of survivors) original participants were re-examined. Detailed examinations, including lens photographs and fasting blood tests, were conducted at both visits. Logistic regression models estimated odds ratios (OR) and 95% confidence intervals (CI) after multivariable adjustment. RESULTS: In this population, those with PSC were older, less likely to have higher education, and more likely to have diabetes and myopia. The PSC prevalence was 5.7% (150/2644). Higher levels of homocysteine (per SD; OR, 1.17; 95% CI, 1.00-1.37) and lower levels of folate (per SD; OR, 1.24; 95% CI, 0.99-1.56) were associated with prevalent PSC. There was significant interaction (P < 0.05) between vitamin B12 and homocysteine; for B12 ≥125 pmol/L, 28% higher PSC prevalence was associated with homocysteine (per SD; OR, 1.28; 95% CI, 1.09-1.52); however, for B12
Shizuya Saika - One of the best experts on this subject based on the ideXlab platform.
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immunohistochemical observation of anterior Subcapsular Cataract in eye with spontaneously regressed retinoblastoma
Journal of Cataract and Refractive Surgery, 2010Co-Authors: Kumi Shirai, Yuka Okada, Shizuya SaikaAbstract:We report the histological findings of secondary Cataract in an eye with a spontaneously regressed retinoblastoma to obtain keys to clarify the mechanism of this phenomenon. During phacoemulsification, opacified anterior capsule was obtained, fixed in formalin, and embedded in paraffin. Paraffin sections of the specimen were histologically observed. Hematoxylin–eosin staining showed extracellular matrix accumulation in the extracted fibrous anterior Subcapsular opacification. Immunohistochemistry revealed the presence of fibrous collagen types and cellular fibronectin. Presumed lens cells amid matrix were positively labeled for vimentin, α-smooth muscle actin, and phospho-Smad2. Histology of the fibrous anterior Subcapsular opacification tissue showed the possibility of epithelial-mesenchymal transition of the lens epithelial cells in the secondary Cataract following a spontaneously regressed retinoblastoma. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.
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a new model of anterior Subcapsular Cataract involvement of tgfbeta smad signaling
Molecular Vision, 2006Co-Authors: Kumi Shirai, Shizuya Saika, Akira Ooshima, Takeshi Tanaka, Yuka Okada, Kathleen C Flanders, Yoshitaka OhnishiAbstract:PURPOSE: To develop a new animal model of anterior Subcapsular Cataract formation by topical application of alkali to the eye and to examine the role of Transforming growth factorbeta/Smad3 (TGFbeta/Smad3) signaling in the formation of this Cataract model. METHODS: Under anesthesia, one eye of adult Wistar rats (n=142) was subjected to alkali burn by topical application of 1 N NaOH. The eye was then histologically examined at specific time intervals. Immunohistochemistry with a battery of antibodies was carried out to examine the epithelial-mesenchymal transition (EMT) in lens epithelium. Enzyme immunoassay was employed to determine the level of growth factors in aqueous humor and lens tissue. Smad3-null mice were also used to examine the role of Smad3 signaling in Cataractogenesis in this model. RESULTS: Two days post-burn of the ocular surface, lens epithelium underwent EMT as evidenced by the upregulation of Snail and alpha-smooth muscle actin and formed a multilayer of cells beneath the capsule. Smad signaling was found to be activated in EMT-type lens cells. The majority of myofibroblast-type lens cells expressed proliferative cell nuclear antigen (PCNA). The total amount of active TGFbeta2, total TGFbeta2, and Fibroblast growth factor 2 (FGF2) increased in the aqueous humor and lens. Loss of Smad3 attenuated, but did not completely abolish, EMT in the lens epithelium. CONCLUSIONS: Topical alkali treatment of the ocular surface readily induces an EMT-type anterior Subcapsular Cataract. Smad3 signaling is involved, but not required, for achievement of EMT in the lens epithelium in this Cataract model.
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A new model of anterior Subcapsular Cataract: involvement of TGFbeta/Smad signaling.
Molecular Vision, 2006Co-Authors: Kumi Shirai, Shizuya Saika, Akira Ooshima, Takeshi Tanaka, Yuka Okada, Kathleen C Flanders, Yoshitaka OhnishiAbstract:PURPOSE: To develop a new animal model of anterior Subcapsular Cataract formation by topical application of alkali to the eye and to examine the role of Transforming growth factorbeta/Smad3 (TGFbeta/Smad3) signaling in the formation of this Cataract model. METHODS: Under anesthesia, one eye of adult Wistar rats (n=142) was subjected to alkali burn by topical application of 1 N NaOH. The eye was then histologically examined at specific time intervals. Immunohistochemistry with a battery of antibodies was carried out to examine the epithelial-mesenchymal transition (EMT) in lens epithelium. Enzyme immunoassay was employed to determine the level of growth factors in aqueous humor and lens tissue. Smad3-null mice were also used to examine the role of Smad3 signaling in Cataractogenesis in this model. RESULTS: Two days post-burn of the ocular surface, lens epithelium underwent EMT as evidenced by the upregulation of Snail and alpha-smooth muscle actin and formed a multilayer of cells beneath the capsule. Smad signaling was found to be activated in EMT-type lens cells. The majority of myofibroblast-type lens cells expressed proliferative cell nuclear antigen (PCNA). The total amount of active TGFbeta2, total TGFbeta2, and Fibroblast growth factor 2 (FGF2) increased in the aqueous humor and lens. Loss of Smad3 attenuated, but did not completely abolish, EMT in the lens epithelium. CONCLUSIONS: Topical alkali treatment of the ocular surface readily induces an EMT-type anterior Subcapsular Cataract. Smad3 signaling is involved, but not required, for achievement of EMT in the lens epithelium in this Cataract model.
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growth factor deposition in anterior Subcapsular Cataract
Journal of Cataract and Refractive Surgery, 2005Co-Authors: Iku Ishida, Shizuya Saika, Yuka Okada, Yoshitaka OhnishiAbstract:Purpose 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. Setting Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan. Methods 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. Results Collagen types I, V, and VI; fibronectin; fibrillin-1; and latent transforming growth factor β 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 α-smooth muscle actin (αSMA). Lens epithelial cells and ECM stained for transforming growth factor β2 (TGFβ2) and TGFβ3 in all samples, but TGFβ1 latency-associated peptide (TGFβ1-LAP) were detected in some samples. Fibroblast growth factor-2 (FGF-2) and hepatocyte growth factor-α (HGF-α) 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 TGFβ signaling, were detected. Conclusions Matrix components (ie, collagen types, fibronectin, fibrillin-1), as well as growth factors such as TGFβ1-LAP, TGFβ2, TGFβ3, FGF-2, and HGF-α, were detected in ASC. Fibrillin-1 might serve as a repository for TGFβs. These growth factors may modulate the phenotypic alteration and behavior of LECs. The MAP kinase cascade and TGFβ signaling are both activated in LECs in ASC.
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aberrant lens fiber differentiation in anterior Subcapsular Cataract formation a process dependent on reduced levels of pax6
Investigative Ophthalmology & Visual Science, 2004Co-Authors: Frank J Lovicu, Shizuya Saika, Philipp Steven, John W McavoyAbstract:PURPOSE. TGFβ can induce development in lenses of opaque Subcapsular fibrotic plaques that have many features of human Subcapsular Cataracts. To understand further the events associated with the onset and progression of TGFβ-induced Cataract, several different models for anterior Subcapsular Cataract (ASC) were used and characterized. METHODS. Anterior Subcapsular plaques were induced in rat lenses cultured with TGFβ and in transgenic mice overexpressing TGFβ in the lens. ASC was also examined in lenses of mice haploinsufficient for Pax6, as well as in human biopsy specimens. Immunofluorescence and in situ hybridization labeling were used to examine changes in patterns of gene expression associated with Cataract formation in these models. RESULTS. Examination of TGFβ-induced Cataract in transgenic mice established that the Subcapsular plaques are composed of a heterogenous cell population: a population of myofibroblastic cells as well as a population of lens-fiber-like cells. Further support for phenotypic change comes from the observation that the cells in these plaques no longer expressed lens epithelial markers, such as Pax6 and Connexin43. Subsequent examination of human biopsy specimens of ASC, as well as lenses from Pax6-deficient mice, showed that the anterior Subcapsular plaques in both cases were also composed of a heterogenous population of cells. In contrast, anterior Subcapsular plaques that developed in vitro in response to TGFβ did not have this same cellular heterogeneity, as no fiber-like cells were present. CONCLUSIONS. These findings suggest that in vivo, during TGFβ-induced Cataract formation, some lens epithelial cells transform into myofibroblastic cells, whereas others differentiate into fiber cells. As this pathologic change is accompanied by altered expression of genes characteristic of the normal lens epithelial cell phenotype and as lenses from Pax6-deficient mice exhibit development of anterior Subcapsular plaques closely resembling those induced by TGFβ in transgenic mice, the authors propose that a reduction in Pax6 levels may be essential for this pathologic process to progress. Furthermore, it is clear from these in vitro studies that TGFβ alone cannot reproduce the same morphologic and molecular changes associated with ASC formation in vivo, indicating that additional molecule(s) in the eye are important in this process.
Victoria M. Flood - One of the best experts on this subject based on the ideXlab platform.
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serum homocysteine vitamin b12 and folate and the prevalence and incidence of posterior Subcapsular Cataract
Investigative Ophthalmology & Visual Science, 2015Co-Authors: Paul Mitchell, Elena Rochtchina, Victoria M. Flood, Robert G. Cumming, Jie Jin WangAbstract:PURPOSE: We assessed associations between serum levels of homocysteine, vitamin B12, and folate, and the prevalence and 5-year incidence of posterior Subcapsular Cataract (PSC) in Blue Mountains Eye Study participants. METHODS: We examined 3508 participants aged 49+ years during 1997 to 2000, including 2334 (75.1% of survivors) original and 1174 (85.2% of those eligible) newly recruited subjects. Five years later (2002-2004), 1952 (76.6% of survivors) original participants were re-examined. Detailed examinations, including lens photographs and fasting blood tests, were conducted at both visits. Logistic regression models estimated odds ratios (OR) and 95% confidence intervals (CI) after multivariable adjustment. RESULTS: In this population, those with PSC were older, less likely to have higher education, and more likely to have diabetes and myopia. The PSC prevalence was 5.7% (150/2644). Higher levels of homocysteine (per SD; OR, 1.17; 95% CI, 1.00-1.37) and lower levels of folate (per SD; OR, 1.24; 95% CI, 0.99-1.56) were associated with prevalent PSC. There was significant interaction (P < 0.05) between vitamin B12 and homocysteine; for B12 ≥125 pmol/L, 28% higher PSC prevalence was associated with homocysteine (per SD; OR, 1.28; 95% CI, 1.09-1.52); however, for B12 <125 pmol/L, nonsignificant lower PSC prevalence was associated with homocysteine (per SD; OR, 0.16; 95% CI, 0.02-1.57). The 5-year PSC incidence was 5.7% (n = 59/1030) with no significant associations with homocysteine, B12, and folate. CONCLUSIONS: Higher serum homocysteine level was associated with PSC prevalence in this population. Vitamin B12 status seemed to modify this association. Lack of longitudinal association could have resulted from insufficient study power.
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Serum homocysteine, vitamin B12, and folate, and the prevalence and incidence of posterior Subcapsular Cataract.
Investigative Ophthalmology & Visual Science, 2014Co-Authors: Paul Mitchell, Elena Rochtchina, Victoria M. Flood, Robert G. Cumming, Jie Jin WangAbstract:PURPOSE: We assessed associations between serum levels of homocysteine, vitamin B12, and folate, and the prevalence and 5-year incidence of posterior Subcapsular Cataract (PSC) in Blue Mountains Eye Study participants. METHODS: We examined 3508 participants aged 49+ years during 1997 to 2000, including 2334 (75.1% of survivors) original and 1174 (85.2% of those eligible) newly recruited subjects. Five years later (2002-2004), 1952 (76.6% of survivors) original participants were re-examined. Detailed examinations, including lens photographs and fasting blood tests, were conducted at both visits. Logistic regression models estimated odds ratios (OR) and 95% confidence intervals (CI) after multivariable adjustment. RESULTS: In this population, those with PSC were older, less likely to have higher education, and more likely to have diabetes and myopia. The PSC prevalence was 5.7% (150/2644). Higher levels of homocysteine (per SD; OR, 1.17; 95% CI, 1.00-1.37) and lower levels of folate (per SD; OR, 1.24; 95% CI, 0.99-1.56) were associated with prevalent PSC. There was significant interaction (P < 0.05) between vitamin B12 and homocysteine; for B12 ≥125 pmol/L, 28% higher PSC prevalence was associated with homocysteine (per SD; OR, 1.28; 95% CI, 1.09-1.52); however, for B12
John W Mcavoy - One of the best experts on this subject based on the ideXlab platform.
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TGF-β1 induces lens cells to accumulate α-smooth muscle actin, a marker for Subcapsular Cataracts
Current Eye Research, 2009Co-Authors: Angela M Hales, M Schulz, Coral G Chamberlain, John W McavoyAbstract:Spindle-shaped myofibroblast-like cells, which contain α-smooth muscle actin, have been described in anterior Subcapsular Cataract and after-Cataract. In a previous study in this laboratory, it was shown that transforming growth factor-β (TGFβ) induces the formation of spindle-shaped cells in lens epithelial explants. The aim of this investigation was to determine whether these TGFβ-induced spindle-shaped cells contain α-smooth muscle actin. Lens epithelial explants were prepared from 21-day-old rats and cultured with either TGFβ1 or basic FGF alone, a combination of both growth factors, or without added growth factors. After three days, cellular changes were monitored by phase contrast microscopy, localisation of filamentous actin with rhodamine-phalloidin, and immunolocalisation and immunoblotting of α-smooth muscle actin.TGFβ induced rapid cell elongation and formation of characteristic spindle-shaped cells in lens epithelial explants in the presence or absence of FGF. These cells contained α-smooth mu...
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aberrant lens fiber differentiation in anterior Subcapsular Cataract formation a process dependent on reduced levels of pax6
Investigative Ophthalmology & Visual Science, 2004Co-Authors: Frank J Lovicu, Shizuya Saika, Philipp Steven, John W McavoyAbstract:PURPOSE: TGFbeta can induce development in lenses of opaque Subcapsular fibrotic plaques that have many features of human Subcapsular Cataracts. To understand further the events associated with the onset and progression of TGFbeta-induced Cataract, several different models for anterior Subcapsular Cataract (ASC) were used and characterized. METHODS: Anterior Subcapsular plaques were induced in rat lenses cultured with TGFbeta and in transgenic mice overexpressing TGFbeta in the lens. ASC was also examined in lenses of mice haploinsufficient for Pax6, as well as in human biopsy specimens. Immunofluorescence and in situ hybridization labeling were used to examine changes in patterns of gene expression associated with Cataract formation in these models. RESULTS: Examination of TGFbeta-induced Cataract in transgenic mice established that the Subcapsular plaques are composed of a heterogenous cell population: a population of myofibroblastic cells as well as a population of lens-fiber-like cells. Further support for phenotypic change comes from the observation that the cells in these plaques no longer expressed lens epithelial markers, such as Pax6 and Connexin43. Subsequent examination of human biopsy specimens of ASC, as well as lenses from Pax6-deficient mice, showed that the anterior Subcapsular plaques in both cases were also composed of a heterogenous population of cells. In contrast, anterior Subcapsular plaques that developed in vitro in response to TGFbeta did not have this same cellular heterogeneity, as no fiber-like cells were present. CONCLUSIONS: These findings suggest that in vivo, during TGFbeta-induced Cataract formation, some lens epithelial cells transform into myofibroblastic cells, whereas others differentiate into fiber cells. As this pathologic change is accompanied by altered expression of genes characteristic of the normal lens epithelial cell phenotype and as lenses from Pax6-deficient mice exhibit development of anterior Subcapsular plaques closely resembling those induced by TGFbeta in transgenic mice, the authors propose that a reduction in Pax6 levels may be essential for this pathologic process to progress. Furthermore, it is clear from these in vitro studies that TGFbeta alone cannot reproduce the same morphologic and molecular changes associated with ASC formation in vivo, indicating that additional molecule(s) in the eye are important in this process.
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aberrant lens fiber differentiation in anterior Subcapsular Cataract formation a process dependent on reduced levels of pax6
Investigative Ophthalmology & Visual Science, 2004Co-Authors: Frank J Lovicu, Shizuya Saika, Philipp Steven, John W McavoyAbstract:PURPOSE. TGFβ can induce development in lenses of opaque Subcapsular fibrotic plaques that have many features of human Subcapsular Cataracts. To understand further the events associated with the onset and progression of TGFβ-induced Cataract, several different models for anterior Subcapsular Cataract (ASC) were used and characterized. METHODS. Anterior Subcapsular plaques were induced in rat lenses cultured with TGFβ and in transgenic mice overexpressing TGFβ in the lens. ASC was also examined in lenses of mice haploinsufficient for Pax6, as well as in human biopsy specimens. Immunofluorescence and in situ hybridization labeling were used to examine changes in patterns of gene expression associated with Cataract formation in these models. RESULTS. Examination of TGFβ-induced Cataract in transgenic mice established that the Subcapsular plaques are composed of a heterogenous cell population: a population of myofibroblastic cells as well as a population of lens-fiber-like cells. Further support for phenotypic change comes from the observation that the cells in these plaques no longer expressed lens epithelial markers, such as Pax6 and Connexin43. Subsequent examination of human biopsy specimens of ASC, as well as lenses from Pax6-deficient mice, showed that the anterior Subcapsular plaques in both cases were also composed of a heterogenous population of cells. In contrast, anterior Subcapsular plaques that developed in vitro in response to TGFβ did not have this same cellular heterogeneity, as no fiber-like cells were present. CONCLUSIONS. These findings suggest that in vivo, during TGFβ-induced Cataract formation, some lens epithelial cells transform into myofibroblastic cells, whereas others differentiate into fiber cells. As this pathologic change is accompanied by altered expression of genes characteristic of the normal lens epithelial cell phenotype and as lenses from Pax6-deficient mice exhibit development of anterior Subcapsular plaques closely resembling those induced by TGFβ in transgenic mice, the authors propose that a reduction in Pax6 levels may be essential for this pathologic process to progress. Furthermore, it is clear from these in vitro studies that TGFβ alone cannot reproduce the same morphologic and molecular changes associated with ASC formation in vivo, indicating that additional molecule(s) in the eye are important in this process.
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tgfβ induces morphological and molecular changes similar to human anterior Subcapsular Cataract
British Journal of Ophthalmology, 2002Co-Authors: Frank J Lovicu, M Schulz, Angela M Hales, Lisa N Vincent, Paul A Overbeek, Coral G Chamberlain, John W McavoyAbstract:Background: Transforming growth factor β (TGFβ) has been shown to induce Subcapsular plaques in cultured rat lenses as well as in lenses of transgenic mice. In the present study the authors have extended their analysis of these Cataract models to determine how closely they mimic human Cataract. In particular, they studied the maturation of Cataract in the transgenic model to determine if it develops similar features as previously described for anterior Subcapsular Cataract (ASC) in humans. Furthermore, they investigated whether both of these animal models express the range of molecular markers that have now been shown to be present in human ASC. Methods: Histology and periodic acid Schiff staining were used to study the development and maturation of Subcapsular plaques in transgenic mice overexpressing TGFβ1 in the lens. Immunolabelling methods were used to identify the molecular markers for ASC in both the transgenic mouse model and in rat lenses cultured with TGFβ2. Results: Histological analysis showed that the Subcapsular plaques that develop in adult transgenic mouse lenses bear a striking similarity to mature human ASC, including the formation of a new epithelial-like layer extending between the Subcapsular plaque and the underlying fibre mass. All known molecular markers for human ASC were induced in both rodent models, including collagen types I and III, tenascin, and fibronectin. They also identified the presence of desmin in these plaques, a putative novel marker for human Cataract. Conclusions: In both transgenic mouse and rat lens culture models TGFβ induces markers similar to those found in human ASC. Atypical expression of these Cataract markers is also characteristic of posterior capsular opacification (PCO). The molecular markers expressed are typical of a myofibroblastic/fibroblastic phenotype and suggest that a common feature of ASC and PCO may be induction of an epithelial-mesenchymal transition by TGFβ.
