Decreased catalase expression and increased susceptibility to oxidative stress in primary cultured corneal fibroblasts from patients with granular corneal dystrophy type II

Impact of perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA) on oxidative stress and metabolic biomarkers in human neuronal cells (SH-SY5Y)

Perfluorinated alkyl substances (PFAS) are pervasive environmental contaminants that have attracted considerable attention due to their widespread utilization, resilient characteristics, adverse health implications, and regulatory scrutiny. Despite documented toxicity in living organisms, the precise molecular mechanisms governing the induced adverse effects remain unclear. This study aims to elucidate mechanisms of toxic action by collecting empirical data sets along oxidative stress and metabolic disruption pathways. We investigated the impact of long-chain PFAS (perfluorooctanoic acid (PFOA)) and its short-chain analog (perfluorobutanoic acid (PFBA)) on human neuronal cells (SH-SY5Y). The functionalities of enzymes associated with oxidative stress (catalase and glutathione reductase) and cellular metabolism (lactate dehydrogenase and pyruvate dehydrogenase) were also characterized. Our results reveal that a 24-hour exposure to PFOA and PFBA generated significant levels of reactive oxygen species. Correspondingly, there was a notable decline in catalase and glutathione reductase activities, with PFBA demonstrating a more pronounced effect. High concentrations of PFOA and PFBA reduced metabolic activity. Lactate dehydrogenase activity was only impacted by a high concentration of PFBA, while pyruvate dehydrogenase activity was decreased with PFBA exposure and increased with PFOA exposure. The findings from this study contribute to the knowledge of PFAS and cell interactions and reveal the potential underlying mechanisms of PFAS-induced toxicity.

Microplastic-induced inhibition of cell adhesion and toxicity evaluation using human dermal fibroblast-derived spheroids

Nanoplastics and microplastics (MPs) can significantly affect marine ecosystems and pose potential risks to human health. Although adverse effects stemming from direct exposure to MPs have been demonstrated at the cellular level in animal models, the potential toxicity of these materials in the human body remains uncertain. In this study, we investigated the three-dimensional (3D) behavior of dermal-derived cells exposed to MPs using artificially manufactured spherical primary polystyrene (PS) particles. To explore these effects, we used cellular spheroids as a 3D cell culture model, examined the size-dependent penetration of PS-MPs, and observed morphological alterations in the spheroids. Furthermore, we assessed changes in physiological activities, including reactive oxygen species, adenosine triphosphate, and lactate dehydrogenase, to elucidate the potential intra- and extracellular toxic reactions to PS-MPs. Additionally, our examination of cell-cell junctions and the extracellular matrix (ECM), along with analysis of the regulators involved in their decreased integrity, revealed negatively influenced changes in expression. This exposure study using spheroid models provides new insights into the potential toxicity of short-term exposure to MPs under conditions that closely resemble in vivo systems.

Oxidative Stress and Cellular Protein Accumulation Are Present in Keratoconus, Macular Corneal Dystrophy, and Fuchs Endothelial Corneal Dystrophy

The aim of the study was to investigate oxidative stress as well as cellular protein accumulation in corneal diseases including keratoconus (KC), macular corneal dystrophy (MCD), and Fuchs endothelial corneal dystrophy (FECD) at their primary affecting sites. Corneal buttons from KC, MCD, and FECD patients, as well as healthy controls, were analyzed immunohistochemically to evaluate the presence of oxidative stress and the function of the proteostasis network. 4-Fydroxynonenal (4-HNE) was used as a marker of oxidative stress, whereas the levels of catalase and heat-shock protein 70 (HSP70) were analyzed to evaluate the response of the antioxidant defense system and molecular chaperones, respectively. Sequestosome 1 (SQSTM1) levels were determined to assess protein aggregation and the functionality of autophagic degradation. Basal epithelial cells of the KC samples showed increased levels of oxidative stress marker 4-HNE and antioxidant enzyme catalase together with elevated levels of HSP70 and accumulation of SQSTM1. Corneal stromal cells and endothelial cells from MCD and FECD samples, respectively, showed similarly increased levels of these markers. All corneal diseases showed the presence of oxidative stress and activation of the molecular chaperone response to sustain protein homeostasis. However, the accumulation of protein aggregates suggests insufficient function of the protective mechanisms to limit the oxidative damage and removal of protein aggregates via autophagy. These results suggest that oxidative stress has a role in KC, MCD, and FECD at the cellular level as a secondary outcome. Thus, antioxidant- and autophagy-targeted therapies could be included as supporting care when treating KC or corneal dystrophies.

Reduced OPA1, Mitochondrial Fragmentation and Increased Susceptibility to Apoptosis in Granular Corneal Dystrophy Type 2 Corneal Fibroblasts

The progressive degeneration of granular corneal dystrophy type 2 (GCD2) corneal fibroblasts is associated with altered mitochondrial function, but the underlying mechanisms are incompletely understood. We investigated whether an imbalance of mitochondrial dynamics contributes to mitochondrial dysfunction of GCD2 corneal fibroblasts. Transmission electron microscopy revealed several small, structurally abnormal mitochondria with altered cristae morphology in GCD2 corneal fibroblasts. Confocal microscopy showed enhanced mitochondrial fission and fragmented mitochondrial tubular networks. Western blotting revealed higher levels of MFN1, MFN2, and pDRP1 and decreased levels of OPA1 and FIS1 in GCD2. OPA1 reduction by short hairpin RNA (shRNA) resulted in fragmented mitochondrial tubular networks and increased susceptibility to mitochondrial stress-induced apoptosis. A decrease in the mitochondrial biogenesis-related transcription factors NRF1 and PGC1α was observed, while there was an increase in the mitochondrial membrane proteins TOM20 and TIM23. Additionally, reduced levels of mitochondrial DNA (mtDNA) were exhibited in GCD2 corneal fibroblasts. These observations suggest that altered mitochondrial fission/fusion and biogenesis are the critical molecular mechanisms that cause mitochondrial dysfunction contributing to the degeneration of GCD2 corneal fibroblasts.

Targeted Expression of TGFBIp Peptides in Mouse and Human Tissue by MALDI-Mass Spectrometry Imaging

Stromal corneal dystrophies are a group of hereditary disorders caused by mutations in the TGFBI gene. The mutant TGFBIp is prone to protein aggregation and the mutant protein gets deposited in the cornea, leading to severe visual impairment. The mutations lead to a corneal specific protein aggregation suggesting the involvement of tissue-specific factors. The exact molecular mechanism of the process of tissue-specific protein aggregation remains to be elucidated. Differential proteolysis of mutant TGFBIp is a critical component of the disease pathology. The differential proteolysis gives rise to shorter peptides that are highly aggregation-prone and initiate the aggregation cascade. Analyzing the proteolytic processing of the different TGFBIp mutant may provide insight to aid in understanding the amyloid aggregation mechanism. We developed a MALDI-MSI methodology to identify expression and spatial localization of TGFBIp peptides in the cornea. Corneal tissue samples were collected from both control and dystrophic patients (with 2 different mutations), embedded in OCT and sectioned. The sections were trypsin digested and subjected to mass spectrometry imaging using a targeted approach to detect TGFBIp. MALDI-MSI identified peptides from TGFBIp that co-localized with the amyloid corneal deposits. In addition to the relative abundance data, the specific location of the peptides across the corneal sections as molecular signatures was also identified. Spatial distribution and intensity of the TGFBIp peptides showed differences between diseased and control models but also between the two LCD phenotypes. The TGFBIp peptide with m/z of 787.474 and m/z of 1179.579 showed increased expression in both LCD mutants compared to the controls. The peptide with m/z of 929.5 showed increased expression in the LCD phenotype with H626R mutation while the peptide with m/z of 1315.802 was abundant in the sample with R124C mutation. This initial report of 2D spatial protein signature and localization of TGFBIp may be expanded to other mutations to understand the proteolytic patterns of TGFBIp in different mutations.

Compound heterozygous mutations in TGFBI cause a severe phenotype of granular corneal dystrophy type 2

We investigated the clinical and genetic features of patients with severe phenotype of granular corneal dystrophy type 2 (GCD2) associated with compound heterozygosity in the transforming growth factor-β-induced (TGFBI) gene. Patients with severe GCD2 underwent ophthalmic examination (best-corrected visual acuity test, intraocular pressure measurement, slit-lamp examination, and slit-lamp photograph analysis) and direct Sanger sequencing of whole-TGFBI. The patient’s family was tested to determine the pedigrees. Five novel mutations (p.(His174Asp), p.(Ile247Asn), p.(Tyr88Cys), p.(Arg257Pro), and p.(Tyr468*)) and two known mutations (p.(Asn544Ser) and p.(Arg179*)) in TGFBI were identified, along with p.(Arg124His), in the patients. Trans-phase of TGFBI second mutations was confirmed by pedigree analysis. Multiple, extensive discoid granular, and increased linear deposits were observed in the probands carrying p.(Arg124His) and other nonsense mutations. Some patients who had undergone phototherapeutic keratectomy experienced rapid recurrence (p.(Ile247Asn) and p.(Asn544Ser)); however, the cornea was well-maintained in a patient who underwent deep anterior lamellar keratoplasty (p.(Ile247Asn)). Thus, compound heterozygosity of TGFBI is associated with the phenotypic variability of TGFBI corneal dystrophies, suggesting that identifying TGFBI second mutations may be vital in patients with extraordinarily severe phenotypes. Our findings indicate the necessity for a more precise observation of genotype–phenotype correlation and additional care when treating TGFBI corneal dystrophies.

Exacerbation of Granular Corneal Dystrophy Type 2 After Small Incision Lenticule Extraction

PURPOSE

To report the outcome of unilateral small incision lenticule extraction (SMILE) in a patient with granular corneal dystrophy type 2 (GCD2).

METHODS

Slit-lamp photography and Fourier domain optical coherence tomography were used to document the clinical course and appearance of the corneas in a patient with genetically determined GCD2 who underwent unilateral SMILE in the right eye.

RESULTS

Slit-lamp examination of a 23-year-old woman revealed 2 faint opacities at the surgical interface approximately 2 months after the SMILE procedure had been performed on her right eye. Nine and 3 typical GCD2 deposits located immediately beneath the Bowman layer were observed in the right and left corneas, respectively. Over time, the deposits at the interface increased in size, density, and number in the right eye. Fourier domain optical coherence tomography performed 33 months after the SMILE procedure revealed deposits at the SMILE interface that were distinct from those located immediately beneath the Bowman layer. The severity of disease exacerbation was less in this patient than what is typically observed in others who have undergone laser-assisted in situ keratomileusis or photorefractive keratectomy.

CONCLUSIONS

SMILE is contraindicated in patients with GCD2, as are other corneal refractive surgical procedures. This case highlights the importance of genetic testing before the performance of refractive corneal procedures-especially for patients with corneal opacities on preoperative slit-lamp examination or a family history of corneal disease compatible with that of a corneal dystrophy.

Patients with Gaucher disease display systemic oxidative stress dependent on therapy status

Gaucher disease is an autosomal recessive metabolic disorder caused by mutations in GBA1, which encodes for the lysosomal hydrolase enzyme, β-glucocerebrosidase. The resulting misfolded protein can trigger endoplasmic reticulum stress and an unfolded protein response within the affected cells. The enzyme deficiency leads to accumulation of its substrates, glucosylceramide and glucosylsphingosine, within macrophage lysosomes and with prominent disease manifestations in macrophage rich tissues. Resultant lysosomal pathology and impaired autophagy leads to redox imbalance, mitochondrial dysfunction and intracellular oxidative stress. Here we have systematically examined a role for oxidative stress in individuals affected by Gaucher disease. We compared multiple oxidative stress biomarkers in plasma and red blood cell samples from patients who are currently untreated, with those who are stable on standard-of-care therapy, and with healthy controls. We found significant differences in key oxidative stress biomarkers in untreated patients compared to healthy control. In treated patients, results generally fell between the controls and the untreated patients. Interestingly, even asymptomatic and minimally symptomatic untreated patients had evidence of significant systemic oxidative stress. We conclude that underlying oxidative stress may contribute to Gaucher disease pathophysiology including long-term adverse outcomes such as Parkinsonism and malignancies. Therapies targeting oxidative stress may prove useful as adjuvant treatments for Gaucher disease and other lysosomal storage disorders.

Determination of Oxidative Stress Markers in the Aqueous Humor and Corneal Tissues of Patients With Congenital Hereditary Endothelial Dystrophy

PURPOSE

The aim of this study is to determine the presence of oxidative stress markers in the aqueous humor (AH) and corneal tissues of patients with congenital hereditary endothelial dystrophy (CHED).

METHODS

Interventional prospective study was undertaken to quantify levels of ascorbic acid and glutathione in the AH of patients with CHED. AH was collected from patients undergoing keratoplasty and levels of ascorbic acid and glutathione were determined using biochemical assays and measured spectrophotometrically. AH collected from pediatric patients with cataract were used as control. Corneal sections of patients who underwent penetrating keratoplasty were obtained, and presence of glutathione peroxidase 1, catalase, and superoxide dismutase was determined by immunohistochemistry. Tissue sections obtained from cadaveric corneas unsuitable for clinical transplant were used as control.

RESULTS

Significantly increased ascorbic acid levels were determined in patients with CHED (605.6 ± 158.9 μM) compared with those in controls (190.5 ± 74.72 μM). However, a trend toward reduced level of glutathione was detected in patients with CHED compared with that in the controls. Increased glutathione peroxidase 1 staining and reduced expression of catalase was detected in corneal tissues of patients with CHED compared with those in control corneal tissues. There was no apparent changes observed in the expression of superoxide dismutase in the corneal sections obtained from patients with CHED.

CONCLUSIONS

To the best of our knowledge, this is the first study to determine the levels of ascorbic acid and glutathione in AH of patients with CHED. Our data suggest the presence of oxidative stress in CHED that might be responsible for the pathological changes in patients with CHED.

Inflammation and oxidative stress induced by lipid peroxidation metabolite 4-hydroxynonenal in human corneal epithelial cells

PURPOSE

Oxidative stress is widely known to be a major contributor in the pathogenesis of dry eye disease (DED). 4-Hydroxynonenal (4-HNE), a well-known byproduct frequently measured as an indicator of oxidative stress-induced lipid peroxidation, has been shown to be elevated in both human and murine corneal DED samples. This study aims to investigate if 4-HNE is responsible for the oxidative stress in human corneal epithelial cells (HCECs) and explores the underlying mechanism by which it confers its effects.

METHODS

SV40-immortalized HCECs were cultured in minimum essential media (MEM) with 1% penicillin/streptomycin and 10% fetal bovine serum. HCECs were exposed to media with or without 4-HNE and cell culture supernatants were collected at 4 and 24 h. Cellular reactive oxygen species (ROS) measurement was performed using a 2',7'-dichlorofluorescein diacetate (DCFDA) assay kit according to the manufacturer's instructions. Protein levels of antioxidant enzymes copper/zinc superoxide dismutase 1 (SOD1) and NAD(P)H quinone dehydrogenase 1 (NQO1) were analyzed by Western blot. NF-κB activation and expression of IL-6 and IL-8 were measured using an NF-κB p65 Total SimpleStep ELISA Kit and Proteome Profiler Human Cytokine Array Kit. Cell viability was evaluated by LDH cytotoxicity assay.

RESULTS

Treatment with 4-HNE decreased cell viability of HCECs. Band intensities corresponding to levels of ROS production showed a significant increase in ROS generation after treatment with 4-HNE. 4-HNE decreased SOD1 levels and upregulated NQO1 expression in HCECs. A significant increase in activation of NF-κB and production of pro-inflammatory cytokines IL-6 and IL-8 was observed after treatment with 4-HNE. Exposure to N-acetylcysteine (NAC), an antioxidant and ROS scavenger, antagonized the oxidative effects of 4-HNE on HCECs.

CONCLUSION

4-HNE induces oxidative stress in corneal epithelial cells by increasing levels of ROS generation and modifying the expression of antioxidant enzyme levels, decreasing cell viability of HCECs in vitro. This study demonstrates a potential pathway by which 4-HNE functions to confer its detrimental effects and provides a new therapeutic target for the treatment of DED.

Uptake of cell debris and enhanced expression of inflammatory factors in response to dead cells in corneal fibroblast cells

Keratocytes synthesize stromal proteins and participate in wound healing through successive differentiation into corneal fibroblasts and myofibroblasts. Cultured keratocytes or corneal fibroblasts are also known as non-professional phagocytes and innate immune cells. However, whether the corneal fibroblasts phagocytize their dead cells and whether the associated innate immunity is enhanced remains unknown. We initially characterized immortalized corneal fibroblast cells with the expression of specific genes. The corneal fibroblasts strongly expressed extracellular matrix molecules (FN and COL1A1) and low or medium levels of macrophage markers (CD14, CD68, and CD36), inflammatory cytokines (IL1A, IL1B, and IL6), and chemokines (IL8 and CCL2), but not CD11b, suggesting that corneal fibroblasts are macrophage-like fibroblasts. We confirmed the phagocytic activity of the corneal fibroblasts with fluorescent dye labeled-dead E. coli and S. aureus bacteria using confocal microscopy and flow cytometry. To test corneal fibroblast phagocytosis of apoptotic and necrotic cells we co-cultured corneal fibroblasts with fluorescent dye labeled-apoptotic and -necrotic cells and analyzed their uptake using fluorescence and confocal microscopy. We observed that corneal fibroblasts can engulf digested or processed cellular debris and entire dead cells. Co-cultured dying and dead cells strongly enhanced the expression of cytokine (IL1A, IL1B, and IL6), chemokine (CCL2, CCL5, CCL20, IL8, and CXCL10), and MMP (MMP1, MMP3, and MMP9) genes through the NF-κB signaling pathway. Our findings suggest that dying and dead cells stimulate corneal fibroblasts to further induce inflammatory factors and that corneal fibroblasts contribute to the clearing of cell debris as non-professional phagocytes.

Involvement of the JNK signaling in granular corneal dystrophy by modulating TGF-β-induced TGFBI expression and corneal fibroblast apoptosis

Granular corneal dystrophy (GCD) is featured by corneal deposits of transforming growth factor beta-induced gene (TGFBI) mediated by the TGF-β (transforming growth factor-β)/Smad signaling. However, the roles of c-Jun amino-terminal kinase (JNK) pathway in GCD pathogenesis remains unexplored, which was investigated in this study. JNK signaling activation and inhibition in primary corneal fibroblasts were obtained by treatments with anisomycin and SP600125, respectively. Protein abundance and phosphorylation were detected by immunoblotting. Cell viability and apoptosis were analyzed by CCK-8 and flow cytometry respectively. TGFBI deposit and autophagy progression were assessed by immunofluorescence. The results found that JNK1 expression and phosphorylation were greatly increased in corneal tissues from GCD2 patients. JNK signaling activation impaired the viability and promoted apoptosis and autophagy processes in primary corneal fibroblasts, along with Smad2/3 phosphorylation, TGFBI accumulation and Bcl-2 suppression. Autophagy related proteins, such as ATG5 (autophagy related 5), ATG12 (autophagy related 12) and LC3B (microtubule-associated protein 1 light chain 3 beta), were also increased in anisomycin or TGF-β1 treated corneal fibroblasts. However, SP600125 effectively reversed the above effect induced by TGF-β1 treatment in corneal fibroblasts, including the TGF-β-induced autophagy progression. The results suggested that JNK signaling was activated in GCD2 corneal tissues, and it mediated the TGF-β-induced TGFBI protein accumulation and apoptosis of corneal fibroblasts during GCD2 pathogenesis.

APP processing and metabolism in corneal fibroblasts and epithelium as a potential biomarker for Alzheimer's disease

Alzheimer's disease (AD) primarily affects the brain and is the most common form of dementia worldwide. Despite more than a century of research, there are still no early biomarkers for AD. It has been reported that AD affects the eye, which is more accessible for imaging than the brain; however, links with the cornea have not been evaluated. To investigate whether the cornea could be used to identify possible diagnostic indicators of AD, we analyzed the proteolytic processing and isoforms of amyloid precursor protein (APP) and evaluated the expression of AD-related genes and proteins in corneal fibroblasts from wild-type (WT) corneas and corneas from patients with granular corneal dystrophy type 2 (GCD2), which is related to amyloid formation in the cornea. Reverse transcription polymerase chain reaction (RT-PCR) analysis was used to assess the expression of AD-related genes, i.e., APP, ADAM10, BACE1, BACE2, PSEN1, NCSTN, IDE, and NEP. RT-PCR and DNA sequencing analysis demonstrated that isoforms of APP770 and APP751, but not APP695, were expressed in corneal fibroblasts. Moreover, the mRNA ratio of APP770/APP751 isoforms was approximately 4:1. Western blot analysis also demonstrated the expression of a disintegrin and metalloprotease domain-containing protein 10 (ADAM10), beta-site APP-cleaving enzyme 1 (BACE1), nicastrin, insulin degradation enzyme, and neprilysin in corneal fibroblasts. Among these targets, the levels of immature ADAM10 and BACE1 protein were significantly increased in GCD2 cells. The expression levels of APP, ADAM10, BACE1, and transforming growth factor-beta-induced protein (TGFBIp) were also detected by western blot in human corneal epithelium. We also investigated the effects of inhibition of the autophagy-lysosomal and ubiquitin-proteasomal proteolytic systems (UPS) on APP processing and metabolism. These pathway inhibitors accumulated APP, α-carboxy-terminal fragments (CTFs), β-CTFs, and the C-terminal APP intracellular domain (AICD) in corneal fibroblasts. Analysis of microRNAs (miRNAs) revealed that miR-9 and miR-181a negatively coregulated BACE1 and TGFBIp, which was directly associated with the pathogenesis of AD and GCD2, respectively. Immunohistochemical analysis indicated that APP and BACE1 were distributed in corneal stroma cells, epithelial cells, and the retinal layer in mice. Collectively, we propose that the cornea, which is the transparent outermost layer of the eye and thus offers easy accessibility, could be used as a potential biomarker for AD diagnosis and progression.

Visual Defects and Ageing

Many diseases are related to age, among these neurodegeneration is particularly important. Alzheimer's disease Parkinson's and Glaucoma have many common pathogenic events including oxidative damage, Mitochondrial dysfunction, endothelial alterations and changes in the visual field. These are well known in the case of glaucoma, less in the case of neurodegeneration of the brain. Many other molecular aspects are common, such as the role of endoplasmic reticulum autophagy and neuronal apoptosis while others have been neglected due to lack of space such as inflammatory cytokine or miRNA. Moreover, the loss of specific neuronal populations, the induction of similar mechanisms of cell injury and the deposition of protein aggregates in specific anatomical areas are very similar events between these diseases. Intracellular and/or extracellular accumulation of protein aggregates is a key feature of many neurodegenerative disorders. The existence of abnormal protein aggregates has been documented in the RGCs of glaucomatous patients such as the anomalous Tau protein or the β-amyloid accumulations. Intra-cell catabolic processes also appear to be common in both glaucoma and neurodegeneration. They also help us to understand how the basis between these diseases is common and how the visual aspects can be a serious problem for those who are affected.

Role of diagnostic factors associated with antioxidative status and expression of matrix metalloproteinases (MMPs) in patients with cancer therapy induced ocular disorders

BACKGROUND

Cancer patients when treated with different chemotherapeutic drugs often develop mild to severe sight threatening diseases during or after chemotherapy. The mechanism involved in the pathogenesis of ocular toxicities is poorly understood. Oxidative stress, inflammation and MMPs (angiogenic factor) are involved in the progression of chemotherapy related ocular disorders.

MATERIALS AND METHODS

The concentration of oxidative stress markers such as MDA, NO and levels of different antioxidant molecules such as SOD, CAT, GSH, GPx, GPr, VIT A, VIT E and VIT C present in the serum of chemotherapy treated patients (n = 50) and in normal persons (n = 20) were estimated by the direct spectrophotometric method while the concentration of TNF-α and MMP-9 activity were determined using human TNF-α and MMP-9 ELISA kits.

RESULTS

The concentration of SOD and CAT (0.356 ± 0.05 μg/dl and 1.26 ± 0.01 μmol/mol of protein) was significantly lower as compared to that (1.09 ± 0.03 μg/dl and 3.99 ± 0.04 μmol/mol of protein) in controls. The levels of GPx (0.06 ± 0.01 mmol/dl) in the cancer patients were much lower than those in the controls (0.78 ± 0.06 mmol/dl). Lower level of GSH (0.96 ± 0.003 μg/dl) in serum of the diseased group was observed as compared to healthy group (7.26 ± 1.40 μg/dl). The level of Vit A, Vit C and Vit E was lower in systemic circulation of cancer patients (109.99 ± 6.35 μg/ml, 1.26 ± 0.36 μg/ml and 1.29 ± 0.191 μg/ml) as compared to control subjects (166.35 ± 14.26 μg/ml, 3.25 ± 0.099 μg/ml and 6.354 ± 2.26 μg/ml) respectively. The concentration of nitric oxide was significantly higher in the cancer patients (45.26 ± 6.35 ng/ml) than that in the normal subjects (16.35 ± 3.26 ng/ml). The higher concentration of MDA (8.65 ± 3.26 nmol/ml) was observed in the patients than normal ones (1.254 ± 0.065 nmol/ml). The quantity of TNF-α was significantly higher in chemotherapy treated patients (32.68 ± 4.33 pg/ml) as compared to the control group (20.979 ± 1.98 pg/ml). Significantly higher concentration of MMP-9 (40.26 ± 3.26 ng/ml) was observed in the cancer patients than the controls (7.256 ± 1.95 ng/ml).

CONCLUSION

Lower levels of antioxidant enzymes and non-enzymatic small molecules and higher levels of oxidative stress and inflammatory clinical parameters such as NO, MDA, TNF-α and MMP-9 may be involved in the pathogenesis of systemic chemotherapy related ocular complications such as cataract, glaucoma, blepharitis, retinitis pigmentosa, macular degeneration, pterygium and retinal degeneration.

Yeast polyubiquitin gene UBI4 deficiency leads to early induction of apoptosis and shortened replicative lifespan

Ubiquitin is a 76-amino acid protein that is highly conserved among higher and lower eukaryotes. The polyubiquitin gene UBI4 encodes a unique precursor protein that contains five ubiquitin repeats organized in a head-to-tail arrangement. Although the involvement of the yeast polyubiquitin gene UBI4 in the stress response was reported long ago, there are no reports regarding the underlying mechanism of this involvement. In this study, we used UBI4-deletion and UBI4-overexpressing yeast strains as models to explore the potential mechanism by which UBI4 protects yeast cells against paraquat-induced oxidative stress. Here, we show that ubi4Δ cells exhibit oxidative stress, an apoptotic phenotype, and a decreased replicative lifespan. Additionally, the reduced resistance of ubi4Δ cells to paraquat that was observed in this study was rescued by overexpression of either the catalase or the mitochondrial superoxide dismutase SOD2. We also demonstrated that only SOD2 overexpression restored the replicative lifespan of ubi4Δ cells. In contrast to the case of ubi4Δ cells, UBI4 overexpression in wild-type yeast increases the yeast's resistance to paraquat, and this overexpression is associated with large pools of expressed ubiquitin and increased levels of ubiquitinated proteins. Collectively, these findings highlight the role of the polyubiquitin gene UBI4 in apoptosis and implicate UBI4 as a modulator of the replicative lifespan.

The Eye, Oxidative Damage and Polyunsaturated Fatty Acids

Polyunsaturated fatty acids (PUFA) are known to have numerous beneficial effects, owing to their anti-inflammatory and antioxidant properties. From a metabolic standpoint, the mitochondria play a fundamental role in cellular homeostasis, and oxidative stress can affect their functioning. Indeed, the mitochondria are the main source of ROS, and an imbalance between ROS and antioxidant defenses leads to oxidative stress. In addition, aging, the decline of cellular functions, and continual exposure to light underlie many diseases, particularly those of the eye. Long-term exposure to insults, such as UV light, visible light, ionizing radiation, chemotherapeutics, and environmental toxins, contribute to oxidative damage in ocular tissues and expose the aging eye to considerable risk of pathological consequences of oxidative stress. Ample antioxidant defenses responsible for scavenging free radicals are essential for redox homeostasis in the eye, indeed, eye tissues, starting from the tear film, which normally are exposed to high oxygen levels, have strong antioxidant defenses that are efficient for protecting against ROS-related injuries. On the contrary, instead, the trabecular meshwork is not directly exposed to light and its endothelial cells are poorly equipped with antioxidant defenses. All this makes the eye a target organ of oxidative damage. This review focuses on the role of the polyunsaturated fatty acids in the human eye, particularly in such pathologies as dry eye, glaucoma, and macular degeneration, in which dietary PUFA supplementation can be a valid therapeutic aid.

Lithium chloride (LiCl) induced autophagy and downregulated expression of transforming growth factor β-induced protein (TGFBI) in granular corneal dystrophy

This study evaluated whether lithium chloride (LiCl) prevents cytoplasmic accumulation of mutant-transforming growth factor β-induced protein (Mut-TGFBI) in granular corneal dystrophy (GCD) via activation of the autophagy pathway. Levels of TGFBI and microtubule-associated protein 1A/1B-light chain 3 (LC3) in 3 GCD patients and healthy controls were analyzed by immunohistochemistry (IHC) staining and Western blot. Primary corneal fibroblasts were isolated and transfected with wild type or mutant type TGFBI over-expressed vectors, and then treated with LiCl and/or autophagy inhibitor 3-methyladenine (3-MA). Then, levels of TGFBI, glycogen synthase kinase-3 (GSK-3) and LC3-I/-II were detected. Cell viability and transmission electron microscopy assay were also performed. Levels of TGFBI and LC3 were significantly increased in GCD patients. Over-expression of mutant type TGFBI inhibited cell viability and induced autophagy in corneal fibroblasts. LiCl downregulated the expression of TGFBI in mutant type TGFBI over-expressed cells in a dose- and time-dependent manner. LiCl enhanced autophagy in mutant type TGFBI over-expressed cells and recovered cell viability in those cells. However, the effects of LiCl were partly attenuated when autophagy was suppressed by 3-MA. To summarize, treatment with LiCl inhibited the expression of TGFBI and recovery the inhibitory of mutant type TGFBI in cell viability, at least part through enhancing of autophagy. These data strongly suggest that LiCl may be useful in the treatment of GCD.

Association Between Visual Acuity and the Corneal Area Occupied by Granular Lesions, Linear Lesions, or Diffuse Haze in Patients With Granular Corneal Dystrophy Type 2

PURPOSE

In granular corneal dystrophy type 2 (GCD2), corneal deposits containing fragments of transforming growth factor-β-induced protein appear in sequence as granular lesions (GLs), linear lesions (LLs), and diffuse haze (DH). We aimed to investigate the association between visual acuity and age-related changes in lesion types in patients with GCD2.

METHODS

We retrospectively evaluated the medical records and slit-lamp photographs of 533 patients (1066 eyes) with genetically confirmed GCD2 (heterozygous). Deposits were classified into GLs, LLs, and DH, after which the area occupied by each lesion type was measured. The associations between visual acuity and each lesion area were also evaluated using univariable and multivariable models.

RESULTS

The area occupied by GLs increased beginning in the teen years, whereas the area occupied by DH began to increase after age 40. However, the area occupied by LLs increased until patients had reached their 40s, after which no further increases occurred. Multivariable analyses revealed no association between GLs and low visual acuity after adjusting for age and sex. Increases in the LL area were associated with lower odds for low visual acuity (adjusted odds ratio = 0.4 for the third tertile, 95% confidence interval, 0.2-0.97), whereas increases in the DH area were positively associated with low visual acuity (adjusted odds ratio = 3.3 for the third tertile of the DH area, 95% confidence interval, 1.3-8.3).

CONCLUSIONS

Our findings indicated that LLs associated with GCD2 do not produce significant decreases in visual acuity, whereas DH exerts the most significant negative impact on visual acuity. Late-onset DH may be associated with the termination of LL formation.

Melatonin reduces endoplasmic reticulum stress and corneal dystrophy-associated TGFBIp through activation of endoplasmic reticulum-associated protein degradation

Endoplasmic reticulum (ER) stress is emerging as a factor for the pathogenesis of granular corneal dystrophy type 2 (GCD2). This study was designed to investigate the molecular mechanisms underlying the protective effects of melatonin on ER stress in GCD2. Our results showed that GCD2 corneal fibroblasts were more susceptible to ER stress-induced death than were wild-type cells. Melatonin significantly inhibited GCD2 corneal cell death, caspase-3 activation, and poly (ADP-ribose) polymerase 1 cleavage caused by the ER stress inducer, tunicamycin. Under ER stress, melatonin significantly suppressed the induction of immunoglobulin heavy-chain-binding protein (BiP) and activation of inositol-requiring enzyme 1α (IRE1α), and their downstream target, alternative splicing of X-box binding protein 1(XBP1). Notably, the reduction in BiP and IRE1α by melatonin was suppressed by the ubiquitin-proteasome inhibitor, MG132, but not by the autophagy inhibitor, bafilomycin A1, indicating involvement of the ER-associated protein degradation (ERAD) system. Melatonin treatment reduced the levels of transforming growth factor-β-induced protein (TGFBIp) significantly, and this reduction was suppressed by MG132. We also found reduced mRNA expression of the ERAD system components HRD1 and SEL1L, and a reduced level of SEL1L protein in GCD2 cells. Interestingly, melatonin treatments enhanced SEL1L levels and suppressed the inhibition of SEL1L N-glycosylation caused by tunicamycin. In conclusion, this study provides new insights into the mechanisms by which melatonin confers its protective actions during ER stress. The results also indicate that melatonin might have potential as a therapeutic agent for ER stress-related diseases including GCD2.

Development of wound healing models to study TGFβ3's effect on SMA

The goal of this study was to test the efficacy of transforming growth factor beta 3 (TGFβ3) in reducing α-smooth muscle actin (SMA) expression in two models-an ex vivo organ culture and an in vitro 3D cell construct-both of which closely mimic an in vivo environment. For the ex vivo organ culture system, a central 6.0 mm corneal keratectomy was performed on freshly excised rabbit globes The corneas were then excised, segregated into groups treated with 1.0 ng/ml TGFβ1 or β3 (T1 or T3, respectively), and cultured for 2 weeks. The corneas were assessed for levels of haze and analyzed for SMA mRNA levels. For the 3D in vitro model, rabbit corneal fibroblasts (RbCFs) were cultured for 4 weeks on poly-transwell membranes in Eagle's minimum essential media (EMEM) + 10% FBS + 0.5 mM vitamin C ± 0.1 ng/ml T1 or T3. At the end of 4 weeks, the constructs were processed for analysis by indirect-immunofluorescence (IF) and RT-qPCR. The RT-qPCR data showed that SMA mRNA expression in T3 samples for both models was significantly lower (p < 0.05) than T1 treatment (around 3-fold in ex vivo and 2-fold in constructs). T3 also reduced the amount of scarring in ex vivo corneas as compared with the T1 samples. IF data from RbCF constructs confirmed that T3-treated samples had up to 4-fold (p < 0.05) lower levels of SMA protein expression than samples treated with T1. These results show that T3 when compared to T1 decreases the expression of SMA in both ex vivo organ culture and in vitro 3D cell construct models. Understanding the mechanism of T3's action in these systems and how they differ from simple cell culture models, may potentially help in developing T3 as an anti-scarring therapy.

Polysorbate-80-coated, polymeric curcumin nanoparticles for in vivo anti-depressant activity across BBB and envisaged biomolecular mechanism of action through a proposed pharmacophore model

Depression is a modern world epidemic. Its main causative factor is oxidative stress, as reported in study subjects. Natural products are yet to show significant therapeutic effects in comparison with synthetic drugs. Current study deals with the preparation of brain-targeted polysorbate-80-coated curcumin PLGA nanoparticles (PS-80-CUR-NP), and their characterisation via Spectral and optical methods. PS-80-CUR-NP were evaluated against the oxidative stress-mediated depressant (OSMD) activity via Force despair, Tail suspension tests and stress biomarker assay (SOD and catalase activity). A significant reduction in immobility (p < 0.01) in force despair and tail suspension test and a significant increase (p < 0.001 and p < 0.01) in SOD and catalase activity was found and compared with stress control, which confirmed the OSMD activity of PS-80-CUR-NP at 5 mg equivalent dose. Further, AUC_(0.5-15 h) curve of brain homogenates estimated the curcumin concentration of 1.73 ng/g C_max at T_max 3 h via HPLC technique.

Evaluation of the wound healing efficacy of chemical and phytogenic silver nanoparticles

Wound healing requires a series of cellular events and a cascade of co-ordinated and systemic biochemical events. Silver nanoparticles possess many beneficial properties for wound management including antibacterial, anti-inflammatory and pro-healing properties. In this study, the authors investigated the wound healing properties of Cinnamomum verum extract mediated nanosilver (CENS) particles in comparison with 1% povidone iodine, citrate mediate NS and CE treatments. The topical application of CENS showed good antibacterial activity and accelerated wound healing with complete epithelialisation and normal re-growth of hair in all three models of study: namely, excision, incision and dead space models in rats compared with all other treatments. CENS was also found to promote collagen synthesis, stabilise wound besides countering oxidative stress and stimulating cellular proliferation CENS could be a novel therapeutic agent for wound management.

Characterization of the mechanism of prolonged adaptation to osmotic stress of Jeotgalibacillus malaysiensis via genome and transcriptome sequencing analyses

Jeotgalibacillus malaysiensis, a moderate halophilic bacterium isolated from a pelagic area, can endure higher concentrations of sodium chloride (NaCl) than other Jeotgalibacillus type strains. In this study, we therefore chose to sequence and assemble the entire J. malaysiensis genome. This is the first report to provide a detailed analysis of the genomic features of J. malaysiensis, and to perform genetic comparisons between this microorganism and other halophiles. J. malaysiensis encodes a native megaplasmid (pJeoMA), which is greater than 600 kilobases in size, that is absent from other sequenced species of Jeotgalibacillus. Subsequently, RNA-Seq-based transcriptome analysis was utilised to examine adaptations of J. malaysiensis to osmotic stress. Specifically, the eggNOG (evolutionary genealogy of genes: Non-supervised Orthologous Groups) and KEGG (Kyoto Encyclopaedia of Genes and Genomes) databases were used to elucidate the overall effects of osmotic stress on the organism. Generally, saline stress significantly affected carbohydrate, energy, and amino acid metabolism, as well as fatty acid biosynthesis. Our findings also indicate that J. malaysiensis adopted a combination of approaches, including the uptake or synthesis of osmoprotectants, for surviving salt stress. Among these, proline synthesis appeared to be the preferred method for withstanding prolonged osmotic stress in J. malaysiensis.

4-Phenylbutyric acid reduces mutant-TGFBIp levels and ER stress through activation of ERAD pathway in corneal fibroblasts of granular corneal dystrophy type 2

Granular corneal dystrophy type 2 (GCD2) is caused by a point mutation (R124H) in the transforming growth factor β-induced (TGFBI) gene. In GCD2 corneal fibroblasts, secretion of the accumulated mutant TGFBI-encoded protein (TGFBIp) is delayed via the endoplasmic reticulum (ER)/Golgi-dependent secretory pathway. However, ER stress as the pathogenic mechanism underlying GCD2 has not been fully characterized. The aim of this study was to confirm whether ER stress is linked to GCD2 pathogenesis and whether the chemical chaperone, 4-phenylbutyric acid (4-PBA), could be exploited as a therapy for GCD2. We found that the ER chaperone binding immunoglobulin protein (BiP) and the protein disulfide isomerase (PDI) were elevated in GCD2. Western bolt analysis also showed a significant increase in both the protein levels and the phosphorylation of the key ER stress kinases, inositol-requiring enzyme 1α (IRE1α) and double stranded RNA activated protein kinase (PKR)-like ER kinase, as well as in levels of their downstream targets, X box-binding protein 1 (XBP1) and activating transcription factor 4, respectively, in GCD2 corneal fibroblasts. GCD2 cells were found to be more susceptible to ER stress-induced cell death than were wild-type corneal fibroblasts. Treatment with 4-PBA considerably reduced the levels of BiP, IRE1α, and XBP1 in GCD2 cells; notably, 4-PBA treatment significantly reduced the levels of TGFBIp without change in TGFBI mRNA levels. In addition, TGFBIp levels were significantly reduced under ER stress and this reduction was considerably suppressed by the ubiquitin proteasome inhibitor MG132, indicating TGFBIp degradation via the ER-associated degradation pathway. Treatment with 4-PBA not only protected against the GCD2 cell death induced by ER stress but also significantly suppressed the MG132-mediated increase in TGFBIp levels under ER stress. Together, these results suggest that ER stress might comprise an important factor in GCD2 pathophysiology and that the effects of 4-PBA treatment might have important implications for the development of GCD2 therapeutics.

Polysaccharide-Rich Fraction of Noni Fruit (Morinda citrifolia L.) as Doxorubicin Co-Chemotherapy: Evaluation of Catalase, Macrophages, and TCD8+ Lymphocytes

Noni fruit (Morinda citrifolia L.) has been acknowledged for its cytotoxic and immunostimulatory activity. Our previous results on the immunomodulatory effect of a noni juice polysaccharide-rich fraction encouraged this research to evaluate the potency of the polysaccharide-rich fraction as co-chemotherapy with doxorubicin (DOX) administration. Macrophage activity (MA) was evaluated with the latex bead method. The phagocytic index (PI) was measured as the number of latex beads ingested by 100 macrophages, while the phagocytosis ratio (PR) was indicated by the percentage of macrophages that ingested three or more latex beads. The CEC was evaluated by using a commercial assay kit, while CD8+ T lymphocyte proliferation was evaluated using a flowcytometry method following in vivo administration. Thirty male Wistar rats were divided into five groups (n = 6 each). The control group received DOX via i.p. at a concentration of 4.67 mg/kg BW on days 1 and 4; four treatment groups received PF p.o. at a concentration of 25; 50; 100; 200 mg/kg BW daily, respectively, and additionally DOX i.p. 4.67 mg/kg BW (days 1 and 4) for 7 days. The phagocytic activity was not affected significantly by PF administration compared to the Dox control, but PF administration at a dose of 25 and 50 mg/kg BW has been proven to increase TCD8+ cell proliferation in combination with DOX. The catalase concentration, on the other hand, significantly decreased following PF administration at a dose of 100 mg/kg BW. The results suggest that the polysaccharide-rich fraction of noni juice might induce immunomodulatory effects via TCD8+ activation, have antioxidant activity, and thus might be a potential candidate to be used as an adjuvant to DOX chemotherapy.

The Role of the Reactive Oxygen Species and Oxidative Stress in the Pathomechanism of the Age-Related Ocular Diseases and Other Pathologies of the Anterior and Posterior Eye Segments in Adults

The reactive oxygen species (ROS) form under normal physiological conditions and may have both beneficial and harmful role. We search the literature and current knowledge in the aspect of ROS participation in the pathogenesis of anterior and posterior eye segment diseases in adults. ROS take part in the pathogenesis of keratoconus, Fuchs endothelial corneal dystrophy, and granular corneal dystrophy type 2, stimulating apoptosis of corneal cells. ROS play a role in the pathogenesis of glaucoma stimulating apoptotic and inflammatory pathways on the level of the trabecular meshwork and promoting retinal ganglion cells apoptosis and glial dysfunction in the posterior eye segment. ROS play a role in the pathogenesis of Leber's hereditary optic neuropathy and traumatic optic neuropathy. ROS induce apoptosis of human lens epithelial cells. ROS promote apoptosis of vascular and neuronal cells and stimulate inflammation and pathological angiogenesis in the course of diabetic retinopathy. ROS are associated with the pathophysiological parainflammation and autophagy process in the course of the age-related macular degeneration.

Pathogenesis and treatments of TGFBI corneal dystrophies

Transforming growth factor beta-induced (TGFBI) corneal dystrophies are a group of inherited progressive corneal diseases. Accumulation of transforming growth factor beta-induced protein (TGFBIp) is involved in the pathogenesis of TGFBI corneal dystrophies; however, the exact molecular mechanisms are not fully elucidated. In this review article, we summarize the current knowledge of TGFBI corneal dystrophies including clinical manifestations, epidemiology, most common and recently reported associated mutations for each disease, and treatment modalities. We review our current understanding of the molecular mechanisms of granular corneal dystrophy type 2 (GCD2) and studies of other TGFBI corneal dystrophies. In GCD2 corneal fibroblasts, alterations of morphological characteristics of corneal fibroblasts, increased susceptibility to intracellular oxidative stress, dysfunctional and fragmented mitochondria, defective autophagy, and alterations of cell cycle were observed. Other studies of mutated TGFBIp show changes in conformational structure, stability and proteolytic properties in lattice and granular corneal dystrophies. Future research should be directed toward elucidation of the biochemical mechanism of deposit formation, the relationship between the mutated TGFBIp and the other materials in the extracellular matrix, and the development of gene therapy and pharmaceutical agents.

Histone methylation levels correlate with TGFBIp and extracellular matrix gene expression in normal and granular corneal dystrophy type 2 corneal fibroblasts

Background

TGFβ1-induced expression of transforming growth factor β-induced protein (TGFBIp) and extracellular matrix (ECM) genes plays a major role in the development of granular corneal dystrophy type 2 (GCD2: also called Avellino corneal dystrophy). Although some key transcription factors are known, the epigenetic mechanisms modulating TGFBIp and ECM expression remain unclear. We examined the role of chromatin markers such as histone H3 lysine methylation (H3Kme) in TGFβ1-induced TGFBIp and ECM gene expression in normal and GCD2-derived human corneal fibroblasts.

Methods

Wild-type (n = 3), GCD2-heterozygous (n = 1), and GCD2-homozygous (n = 3) primary human corneal fibroblasts were harvested from human donors and patients prepared. Microarray and gene-expression profiling, Chromatin immunoprecipitation microarray analysis, and Methylated DNA isolation assay-assisted CpG microarrays was performed in Wild-type and GCD2-homozygous human cells.

Results

Transcription and extracellular-secretion levels of TGFBIp were high in normal cells compared with those in GCD2-derived cells and were related to H3K4me3 levels but not to DNA methylation over the TGFBI locus. TGFβ1 increased the expression of TGFBIp and the ECM-associated genes connective tissue growth factor, collagen-α2[Ι], and plasminogen activator inhibitor-1 in normal corneal fibroblasts. Increased levels of gene-activating markers (H3K4me1/3) and decreased levels of repressive markers (H3K27me3) at the promoters of those gene accompanied the changes in expression. TGFβ1 also increased recruitment of the H3K4 methyltransferase MLL1 and of SET7/9 and also the binding of Smad3 to the promoters. Knockdown of both MLL1 and SET7/9 significantly blocked the TGFβ1-induced gene expression and inhibited TGFβ1-induced changes in promoter H3K4me1/3 levels. Those effects were very weak, however, in GCD2-derived corneal fibroblasts.

Conclusions

Taken together, the results show the functional role of H3K4me in TGFβ1-mediated TGFBIp and ECM gene expression in corneal fibroblasts. Pharmacologic and other therapies that regulate these modifications could have potential cornea-protective effects for granular corneal dystrophy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12920-015-0151-8) contains supplementary material, which is available to authorized users.

Effects of EGCG content in green tea extract on pharmacokinetics, oxidative status and expression of inflammatory and apoptotic genes in the rat ocular tissues

Green tea extract (GTE) exerts antioxidative activities in ocular tissues of rats, but high levels of (-)-epigallocatechin gallate (EGCG) can induce oxidative stress. In this study, pharmacokinetics, diurnal variation of oxidative status, antioxidation and transcription factors changes in ocular tissues of rats were investigated. Rats were fed intragastrically with GTE and catechin mixtures containing different amounts of EGCG. Plasma and various ocular tissues were taken for pharmacokinetic analysis, oxidation marker testings and gene expression assays. Effects of EGCG on ocular oxidation status were assessed by 8-isoprostane level and reduced/oxidized glutathione ratio. Oxidation, inflammation and apoptosis regulations in retina were evaluated by real-time polymerase chain reaction. Epicatechin, epigallocatechin and EGCG were dominant in various ocular tissues except vitreous humor, where gallocatechin was predominant. Diurnal variation of oxidative status was found in some compartments. GTE caused oxidative stress increase in the plasma, aqueous humor, vitreous humor, cornea and retina but decrease in the lens and choroid-sclera. Catechins mixture containing half dose of EGCG lowered 8-isoprostane in the retina and lens. GTE treatment induced superoxide dismutase 1 and glutathione peroxidase-3 expressions but suppressed catalase in the retina. Our results reveal pro-oxidation of GTE with high EGCG content to the ocular tissues. Optimal EGCG level is needed for protection.

Development of a Transgenic Mouse with R124H Human TGFBI Mutation Associated with Granular Corneal Dystrophy Type 2

PURPOSE

To investigate the phenotype and predisposing factors of a granular corneal dystrophy type 2 transgenic mouse model.

METHODS

Human TGFBI cDNA with R124H mutation was used to make a transgenic mouse expressing human protein (TGFBIR124H mouse). Reverse transcription PCR (RT-PCR) was performed to analyze TGFBIR124H expression. A total of 226 mice including 23 homozygotes, 106 heterozygotes and 97 wild-type mice were examined for phenotype. Affected mice were also examined by histology, immunohistochemistry and electron microcopy.

RESULTS

RT-PCR confirmed the expression of TGFBIR124H in transgenic mice. Corneal opacity defined as granular and lattice deposits was observed in 45.0% of homozygotes, 19.4% of heterozygotes. The incidence of corneal opacity was significantly higher in homozygotes than in heterozygotes (p = 0.02). Histology of affected mice was similar to histology of human disease. Lesions were Congo red and Masson Trichrome positive, and were observed as a deposit of amorphous material by electron microscopy. Subepithelial stroma was also stained with thioflavin T and LC3, a marker of autophagy activation. The incidence of corneal opacity was higher in aged mice in each group. Homozygotes were not necessarily more severe than heterozygotes, which deffers from human cases.

CONCLUSIONS

We established a granular corneal dystrophy type 2 mouse model caused by R124H mutation of human TGFBI. Although the phenotype of this mouse model is not equivalent to that in humans, further studies using this model may help elucidate the pathophysiology of this disease.

Molecular Pathogenesis of Corneal Dystrophies: Schnyder Dystrophy and Granular Corneal Dystrophy type 2

The International Committee for Classification of Corneal Dystrophies (IC3D) provides updated data to ophthalmologists by incorporating traditional definitions of corneal dystrophies with new genetic, clinical, and pathologic information. Recent advances in the genetics of corneal dystrophies facilitate more precise classifications and elucidate each classification's molecular mechanisms. Unfortunately, the molecular mechanisms and underlying pathogenic mechanisms have remained obscure, with the exception of Schnyder corneal dystrophy (CD), granular CD type 2 (GCD2), and Fuch's endothelial CD. Here, we review the pathogenesis of Schnyder CD and GCD2.

Inhibitory Effect of Tranilast on Transforming Growth Factor-Beta-Induced Protein in Granular Corneal Dystrophy Type 2 Corneal Fibroblasts

PURPOSE

To investigate the effects of tranilast, an inhibitor of chemical mediators and fibroblast proliferation, on the expression of transforming growth factor-beta (TGF-β)-induced protein (TGFBIp) in wild-type (WT) and homozygous (HO) granular corneal dystrophy type 2 corneal fibroblasts.

METHODS

Cell proliferation and cytotoxicity were measured by Cell Counting Kit-8 and lactate dehydrogenase assay. Western blotting and real-time polymerase chain reaction were used to determine changes in the expression of TGFBIp and TGFBI mRNA. We determined the effects of tranilast on phosphorylated Smad2 (pSmad2) and pSmad3, wound-healing, and expression of alpha-smooth muscle actin (α-SMA), type I collagen, and integrins.

RESULTS

High concentrations of tranilast decreased proliferation of corneal fibroblasts but did not cause elevation of lactate dehydrogenase, except at 1.0 mM tranilast. TGF-β increased the expression of TGFBIp and TGFBI mRNA in WT and HO corneal fibroblasts. Cotreatment of corneal fibroblasts with tranilast and TGF-β reduced the levels of TGFBIp and TGFBI mRNA. In addition, application of tranilast reduced pSmad2 in WT and HO corneal fibroblasts and pSmad3 in HO corneal fibroblasts, both of which were increased initially by TGF-β. Tranilast delayed wound healing and reduced the expression of α-SMA, type I collagen, and some of integrins in WT and HO corneal fibroblasts.

CONCLUSIONS

Application of tranilast in WT and HO corneal fibroblasts inhibited the expression of TGFBIp by blocking TGF-β signaling. Thus, tranilast may be useful in delaying or preventing the recurrence of corneal opacity in TGFBI-linked corneal dystrophies if clinical studies confirm these findings.

The oxidant role of 4-hydroxynonenal in corneal epithelium

4-Hydroxynonenal (4-HNE or HNE) is a main endogenous product of cellular lipid peroxidation in tissues and is reported to play pathogenic roles in eye diseases. Here we investigated the association between 4-HNE and oxidative stress in the corneal epithelium. 4-HNE suppressed the cell viability of human corneal epithelial cells (HCE) in a concentration dependent manner. 4-HNE significantly increased the level of 3-Nitrotyrosine (3-NT), a marker of oxidative stress, in HCE cells and corneal epithelium of rats by immunofluorescent staining and Western blot analysis. To its underlying mechanistic on ROS system, 4-HNE elevated the ROS generation enzyme NADPH oxidase 4 (NOX4) and induced the activation of NF-E2–related factor-2 (NRF2) and its downstream effectors: NAD(P)H dehydrogenase (quinone 1) (NQO1) and glutathione S-transferase P (GSTP). Furthermore, N-acetylcysteine (NAC), an antioxidant and ROS scavenger, antagonized the inhibitory and oxidant effects of 4-HNE on the corneal epithelial cells. In conclusion, 4-HNE plays an oxidant role in the corneal epithelium and this work provides a new strategy for the pathogenesis and treatment of corneal diseases.

Lattice corneal dystrophy type IIIA with hyaline component from a novel A620P mutation and distinct surgical treatments

PURPOSE

The aim of this study was to report a lattice corneal dystrophy (LCD) family with a novel mutation of A620P in the TGFBI gene, its long-term treatment, follow-up data, and related pathologic findings.

METHODS

A total of 28 family members were clinically examined, and blood samples or buccal epithelial cells were taken for DNA analysis. All exons from the entire TGFBI gene coding region were analyzed for mutations in 3 affected members. Exon 14 was amplified in other family members and in 100 normal Korean persons as control. Corneal tissues from 1 affected family member were examined using light and electron microscopy.

RESULTS

Clinical examination revealed relatively late-onset LCD with asymmetric progression and recurrent corneal erosion. The affected family members have been treated with penetrating keratoplasty, deep lamellar keratoplasty, and phototherapeutic keratectomy for up to 19 years. Screening of the TGFBI gene revealed a novel A620P mutation, which was found in all affected members. The amyloid origin of deposits was confirmed by Congo red and was also partially stained with Masson trichrome. Although there were no electron-dense bodies as in granular dystrophy, transmission electron microscopy demonstrated that the stromal deposits were not homogenous and contained a variety of constituents with different electron densities.

CONCLUSIONS

We present the characteristics and surgical treatment of corneas with a novel A620P mutation in TGFBI showing LCD type IIIA with hyaline component.

Lysosomal trafficking of TGFBIp via caveolae-mediated endocytosis

Transforming growth factor-beta-induced protein (TGFBIp) is ubiquitously expressed in the extracellular matrix (ECM) of various tissues and cell lines. Progressive accumulation of mutant TGFBIp is directly involved in the pathogenesis of TGFBI-linked corneal dystrophy. Recent studies reported that mutant TGFBIp accumulates in cells; however, the trafficking of TGFBIp is poorly understood. Therefore, we investigated TGFBIp trafficking to determine the route of its internalization and secretion and to elucidate its roles in the pathogenesis of granular corneal dystrophy type 2 (GCD2). Our data indicate that newly synthesized TGFBIp was secreted via the endoplasmic reticulum/Golgi-dependent secretory pathway, and this secretion was delayed in the corneal fibroblasts of patients with GCD2. We also found that TGFBIp was internalized by caveolae-mediated endocytosis, and the internalized TGFBIp accumulated after treatment with bafilomycin A1, an inhibitor of lysosomal degradation. In addition, the proteasome inhibitor MG132 inhibits the endocytosis of TGFBIp. Co-immunoprecipitation revealed that TGFBIp interacted with integrin α_Vβ₃. Moreover, treatment with arginine-glycine-aspartic acid (RGD) tripeptide suppressed the internalization of TGFBIp. These insights on TGFBIp trafficking could lead to the identification of novel targets and the development of new therapies for TGFBI-linked corneal dystrophy.

Antioxidant properties of amniotic membrane: novel observations from a pilot study

OBJECTIVE

Amniotic membrane (AM) is used to manage various debilitated ocular surface conditions. The impact of oxidative stress and free radicals on the ocular surface is increasingly being recognized. Hyaluronic acid (HA) has anti-inflammatory properties and is abundantly present in AM. In this in vitro pilot study, we investigated the potential of AM for intrinsic free radical scavenging properties.

METHODS

Strips of AM were incubated in sealed tubes with hydrogen peroxide (H2O2). After being sonicated, uptake of reactive oxygen species (ROS) was measured by the Amplex Red Hydrogen Peroxide/Peroxidase assay. For comparison, 1630 kDA HA was used.

RESULTS

There was uptake of ROS by all AM samples, which decreased with increasing concentrations of H2O2. Mean ROS uptake for 5 different AMs at 1 hour was significantly greater for 50 μM (83%; SD 11.7, SEM 5.23) compared with 100 μM (67%; SD 20.48, SEM 9.16; p = 0.028; 95% CI 2.8-29.2). The HA comparison group showed similar uptake and trend.

CONCLUSION

This pilot study demonstrates that AM is able to remove ROS from its environment. Demonstrating total antioxidant capacity in AM provides evidence for use as a free radical scavenger. The antioxidant properties of AM and the contribution from HA require more research.

α-Tocopherol mediated amelioration of camptothecin-induced free radical damage to avert cardiotoxicities

Reactive oxygen species (ROS) such as O2(-), hydrogen peroxide, and OH(-) are highly toxic to cells. Cellular antioxidant enzymes and free radical scavengers normally protect a cell from toxic effects of ROS. However, when generation of ROS overtakes the antioxidant defense of the cells, it leads to various pathological conditions. The present study investigated the protective efficacy of α-tocopherol on the peroxidative damage and abnormal antioxidant levels in the myocardial tissue of camptothecin (CPT), administered at the dosage of 6 mg/kg/day in male Wistar rats. CPT-administered rats showed significant increase (p < 0.001) in lipid peroxidation and abnormal changes in the activities/levels of antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, glutathione S-transferase) and nonenzymic antioxidants (reduced glutathione and vitamin E). Alterations in the levels of tissue alkaline phosphatase, lactate dehydrogenase (p < 0.01), alanine transaminase (p < 0.001), and aspartate transaminase (p < 0.001) were also observed in CPT-treated rats. In contrast, rats pretreated with α-tocopherol showed significant revision of elevated levels of lipid peroxides and abnormal antioxidant enzyme activity suggesting the ameliorative property of vitamin E. Histopathological alterations in the heart tissue observed after CPT administration were also protected in animals that were pretreated with vitamin E. Based on our results, we conclude that supplementation of vitamin E may improve the efficacy of standard and experimental cancer therapies by subsiding the toxic effect of the antineoplastic agent.

Biochemical properties and aggregation propensity of transforming growth factor-induced protein (TGFBIp) and the amyloid forming mutants

TGFBI-associated corneal dystrophies are characterized by accumulation of insoluble deposits of the mutant protein transforming growth factor β-induced protein (TGFBIp) in the cornea. Depending on the nature of mutation, the lesions appear as granular (non-amyloid) or lattice lines (amyloid) in the Bowman's layer or in the stroma. This review article emphasizes the structural biology aspects of TGFBIp. We discuss the tinctorial properties and ultrastructure of deposits observed in granular and lattice corneal dystrophic mutants with amyloid and non-amyloid forms of other human protein deposition diseases and review the biochemical and putative functional role of the protein. Using bioinformatics tools, we identify intrinsic aggregation propensity and discuss the possible protective role of gatekeepers close to the "aggregation-prone" regions of native TGFBIp. We describe the relative aggregation rates of lattice corneal dystrophy (LCD) and granular corneal dystrophy (GCD2) mutants using the three-parameter model, which is based on intrinsic properties of polypeptide chains. The predictive power of this model is compared with two other algorithms. We conclude that the model is able to predict the aggregation rate of mutants which do not alter overall net charge of the protein. The need to understand the mechanism of corneal dystrophies from the structural biology viewpoint is emphasized.

Focus on molecular events in the anterior chamber leading to glaucoma

Primary open-angle glaucoma is a multifactorial disease that affects the retinal ganglion cells, but currently its therapy is to lower the eye pressure. This indicates a definite involvement of the trabecular meshwork, key region in the pathogenesis of glaucoma. This is the first target of glaucoma, and its functional complexity is a real challenge to search. Its functions are those to allow the outflow of aqueous humor and not the reflux. This article describes the morphological and functional changes that happen in anterior chamber. The "primus movens" is oxidative stress that affects trabecular meshwork, particularly its endothelial cells. In these develops a real mitochondriopaty. This leads to functional impotence, the trabecular meshwork altering both motility and cytoarchitecture. Its cells die by apoptosis, losing barrier functions and altering the aqueous humor outflow. All the morphological alterations occur that can be observed under a microscope. Intraocular pressure rises and the malfunctioning trabecular meshwork endotelial cells express proteins that completely alter the aqueous humor. This is a liquid whose functional proteomics complies with the conditions of the trabecular meshwork. Indeed, in glaucoma, it is possible detect the presence of proteins which testify to what occurs in the anterior chamber. There are six classes of proteins which confirm the vascular endothelium nature of the anterior chamber and are the result of the morphofunctional trabecular meshwork decay. It is possible that, all or in part, these proteins can be used as a signal to the posterior pole.

Granular corneal dystrophy: a novel approach to classification and treatment

PURPOSE

The purpose of this case report is to review granular corneal dystrophy (GCD) and examine the new paradigm in its classification and treatment.

CASE REPORT

A 49-year-old white male patient reported yearly for monitoring of GCD. He had an ocular surgical history in the left eye for penetrating keratoplasty in 1989 and phototherapeutic keratectomy with mitomycin C for graft recurrence of stromal bread-crumb opacities 17+ years later in 2002. At his last examination, the patient's vision and comfort was stable in each eye, with minimal recurrence of granular opacities in the left surgical eye, stable granular opacities in the right eye, no recurrent corneal erosion symptoms in either eye, and best spectacle-corrected vision of 20/40 OD and 20/30 OS.

CONCLUSIONS

GCD is a Category 1, Stromal, TGFBI-associated corneal dystrophy. Although it is classified as a stromal dystrophy, research suggests the possibility that the granular opacities have an origination to the corneal epithelium with a migratory effect to the corneal stroma. Patients with Groenouw I, like the one in this report, usually do not have severely compromised vision. When vision is significantly affected or recurrent corneal erosion occurs, despite first- and second-line treatments, viable management options thereafter include photokeratectomy and other new surgical treatments such as femtosecond deep anterior lamellar keratoplasty and femtosecond laser-assisted keratoplasty. Future advancements in diagnostic technology, immunohistologic and genetic testing, medications, and surgery will allow for advancements in treating and managing patients with GCD.

Melatonin induces autophagy via an mTOR-dependent pathway and enhances clearance of mutant-TGFBIp

The hallmark of granular corneal dystrophy type 2 (GCD2) is the deposit of mutant transforming growth factor-β (TGF-β)-induced protein (TGFBIp) in the cornea. We have recently shown that there is a delay in autophagic degradation of mutant-TGFBIp via impaired autophagic flux in GCD2 corneal fibroblasts. We hypothesized that melatonin can specifically induce autophagy and consequently eliminate mutant-TGFBIp in GCD corneal fibroblasts. Our results show that melatonin activates autophagy in both wild-type (WT) and GCD2-homozygous (HO) corneal fibroblast cell lines via the mammalian target of rapamycin (mTOR)-dependent pathway. Melatonin treatment also led to increased levels of beclin 1, which is involved in autophagosome formation and maturation. Furthermore, melatonin significantly reduced the amounts of mutant- and WT-TGFBIp. Treatment with melatonin counteracted the autophagy-inhibitory effects of bafilomycin A1, a potent inhibitor of autophagic flux, demonstrating that melatonin enhances activation of autophagy and increases degradation of TGFBIp. Cotreatment with melatonin and rapamycin, an autophagy inducer, had an additive effect on mutant-TGFBIp clearance compared to treatment with either drug alone. Treatment with the selective melatonin receptor antagonist luzindole did not block melatonin-induced autophagy. Given its ability to activate autophagy, melatonin is a potential therapeutic agent for GCD2.