Increased expression of advanced glycation end-products and their receptor, and activation of nuclear factor kappa-B in lacrimal glands of diabetic rats

Inflammation mechanism and anti-inflammatory therapy of dry eye

Dry eye is a widespread chronic inflammatory disease that causes fatigue, tingling, burning, and other symptoms. Dry eye is attributed to rheumatic diseases, diabetes, hormone disorders, and contact lenses, which activate inflammatory pathways: mitogen-activated protein kinases (MAPK) and nuclear factor-B (NF-κB), promote macrophage inflammatory cell and T cell activation, and inflammation factors. Clinicians use a combination of anti-inflammatory drugs to manage different symptoms of dry eye; some of these anti-inflammatory drugs are being developed. This review introduces the dry eye inflammation mechanisms and the involved inflammatory factors. We also elucidate the anti-inflammatory drug mechanism and the detection limits.

Diabetes-Associated Hyperglycemia Causes Rapid-Onset Ocular Surface Damage

Purpose

The metabolic alterations due to chronic hyperglycemia are well-known to cause diabetes-associated complications. Short-term hyperglycemia has also been shown to cause many acute changes, including hemodynamic alterations and osmotic, oxidative, and inflammatory stress. The present study was designed to investigate whether diabetes-associated hyperglycemia can cause rapid-onset detrimental effects on the tear film, goblet cells, and glycocalyx and can lead to activation of an inflammatory cascade or cellular stress response in the cornea.

Methods

Mouse models of type 1 and type 2 diabetes were used. Tear film volume, goblet cell number, and corneal glycocalyx area were measured on days 7, 14, and 28 after the onset of hyperglycemia. Transcriptome analysis was performed to quantify changes in 248 transcripts of genes involved in inflammatory, apoptotic, and stress response pathways.

Results

Our data demonstrate that type 1 and type 2 diabetes-associated hyperglycemia caused a significant decrease in the tear film volume, goblet cell number, and corneal glycocalyx area. The decrease in tear film and goblet cell number was noted as early as 7 days after onset of hyperglycemia. The severity of ocular surface injury was significantly more in type 1 compared to type 2 diabetes. Diabetes mellitus also caused an increase in transcripts of genes involved in the inflammatory, apoptotic, and cellular stress response pathways.

Conclusions

The results of the present study demonstrate that diabetes-associated hyperglycemia causes rapid-onset damage to the ocular surface. Thus, short-term hyperglycemia in patients with diabetes mellitus may also play an important role in causing ocular surface injury and dry eye.

Distinct Inflammatory and Oxidative Effects of Diabetes Mellitus and Hypothyroidism in the Lacrimal Functional Unit

Diabetes mellitus (DM) and hypothyroidism (HT) are prevalent diseases associated with dry eye (DE). Their impact on the lacrimal functional unit (LFU) is poorly known. This work evaluates the changes in the LFU in DM and HT. Adult male Wistar rats had the disease induced as follows: (a) DM: streptozotocin and (b) HT: methimazole. The tear film (TF) and blood osmolarity were measured. Cytokine mRNA was compared in the lacrimal gland (LG), trigeminal ganglion (TG), and cornea (CO). Oxidative enzymes were evaluated in the LG. The DM group showed lower tear secretion (p = 0.02) and higher blood osmolarity (p < 0.001). The DM group presented lower mRNA expression of TRPV1 in the cornea (p = 0.03), higher Il1b mRNA expression (p = 0.03), and higher catalase activity in the LG (p < 0.001). The DM group presented higher Il6 mRNA expression in the TG (p = 0.02). The HT group showed higher TF osmolarity (p < 0.001), lower expression of Mmp9 mRNA in the CO (p < 0.001), higher catalase activity in the LG (p = 0.002), and higher expression of Il1b mRNA in the TG (p = 0.004). The findings revealed that DM and HT induce distinct compromises to the LG and the entire LFU.

The effect of a-Lipoic acid (ALA) on oxidative stress, inflammation, and apoptosis in high glucose-induced human corneal epithelial cells

PURPOSE

Oxidative stress and inflammation had been proved to play important role in the progression of diabetic keratopathy (DK). The excessive accumulation of AGEs and their bond to AGE receptor (RAGE) in corneas that cause the formation of oxygen radicals and the release of inflammatory cytokines, induce cell apoptosis. Our current study was aimed to evaluate the effect of ALA on AGEs accumulation as well as to study the molecular mechanism of ALA against AGE-RAGE axis mediated oxidative stress, apoptosis, and inflammation in HG-induced HCECs, so as to provide cytological basis for the treatment of DK.

METHODS

HCECs were cultured in a variety concentration of glucose medium (5.5, 10, 25, 30, 40, and 50 mM) for 48 h. The cell proliferation was evaluated by CCK-8 assay. Apoptosis was investigated with the Annexin V- fluorescein isothiocyanate (V-FITC)/PI kit, while, the apoptotic cells were determined by flow cytometer and TUNEL cells apoptosis Kit. According to the results of cell proliferation and cell apoptosis, 25 mM glucose medium was used in the following HG experiment. The effect of ALA on HG-induced HCECs was evaluated. The HCECs were treated with 5.5 mM glucose (normal glucose group, NG group), 5.5 mM glucose + 22.5 mM mannitol (osmotic pressure control group, OP group), 25 mM glucose (high glucose group, HG group) and 25 mM glucose + ALA (HG + ALA group) for 24 and 48 h. The accumulation of intracellular AGEs was detected by ELISA kit. The RAGE, catalase (CAT), superoxide dismutase 2 (SOD2), cleaved cysteine-aspartic acid protease-3 (Cleaved caspase-3), Toll-like receptors 4 (TLR4), Nod-like receptor protein 3 (NLRP3) inflammasome, interleukin 1 beta (IL-1 ß), and interleukin 18 (IL-18) were quantified by RT-PCR, Western blotting, and Immunofluorescence, respectively. Reactive oxygen species (ROS) production was evaluated by fluorescence microscope and fluorescence microplate reader.

RESULTS

When the glucose medium was higher than 25 mM, cell proliferation was significantly inhibited and apoptosis ratio was increased (P < 0.001). In HG environment, ALA treatment alleviated the inhibition of HCECs in a dose-dependent manner, 25 μM ALA was the minimum effective dose. ALA could significantly reduce the intracellular accumulation of AGEs (P < 0.001), activate protein and genes expression of CAT and SOD2 (P < 0.001), and therefore inhibited ROS-induced oxidative stress and cells apoptosis. Besides, ALA could effectively down-regulate the protein and gene level of RAGE, TLR4, NLRP3, IL-1B, IL-18 (P < 0.05), and therefore alleviated AGEs-RAGE-TLR4-NLRP3 pathway-induced inflammation in HG-induced HCECs.

CONCLUSION

Our study indicated that ALA could be a desired treatment for DK due to its potential capacity of reducing accumulation of advanced glycation end products (AGEs) and down-regulating AGE-RAGE axis-mediated oxidative stress, cell apoptosis, and inflammation in high glucose (HG)-induced human corneal epithelial cells (HCECs), which may provide cytological basis for therapeutic targets that are ultimately of clinical benefit.

The Gengnianchun recipe attenuates insulin resistance-induced diminished ovarian reserve through inhibiting the senescence of granulosa cells

INTRODUCTION

Insulin resistance (IR) is found in patients with polycystic ovary syndrome (PCOS), but the effects and mechanisms of IR on diminished ovarian reserve (DOR) remain unclear. This study set out to investigate the effects of IR on ovarian reserve; to explore the effects of high concentrations of insulin on the function of ovarian cells in vitro; and to validate the hypothesis that the Gengnianchun recipe (GNC) helps to attenuate DOR caused by IR through reducing the senescence of granulosa cells.

METHODS

Estrus cycle, follicle count, and sex hormone levels were detected to evaluate ovarian function in mice with IR caused by feeding a high-fat diet (HFD). In addition, KGN cells (human granulosa cell line) were treated with high concentrations of insulin. The staining for senescence-associatedβ-galactosidase (SA-β-gal), cell cycle, and expression levels of mRNA and gene proteins related to cell aging were detected in KGN cells treated with high concentrations of insulin. Mice treated with an HFD were fed metformin, GNC, or saline solution for 6 weeks by oral gavage. HOMA-IR, the area under the curve (AUC) of the oral glucose tolerance test (OGTT), levels of fasting blood glucose (FBG), and fasting serum insulin (FINS) were examined to confirm the IR status. Then estrus cycle, follicle count, and sex hormone levels were detected to evaluate ovarian function. Expression levels of mRNA and gene proteins related to cell aging were detected in the ovarian tissue of mice in each group.

RESULTS

The results demonstrated that IR reduced murine ovarian reserves, and high doses of insulin caused granulosa cells to senesce. There was a considerable improvement in HFD-induced IR status in the metformin (Met) and GNC treatment groups. In addition, the expression levels of aging-associated biomarkers were much lower in GNC mice than Met mice; and both the latter groups had considerably lower levels than the HFD group. Moreover, higher follicle counts in different stages and shorter diestrus in the Met or GNC groups compared to the HFD group indicated that ovarian aging could be largely reversed.

DISCUSSION

This work showed that: IR impaired ovarian reserve; high concentrations of insulin induced granulosa cell aging; and GNC attenuated ovarian function through inhibiting IR-induced cell aging.

The Effects of Systemic Coenzyme Q10 Treatment on Corneal Histology in Streptozocin-Induced Diabetic Rats

OBJECTIVE

This study investigate the histopathological changes and VEGF, IL-1β, and IL-6 immunoreactivities in cornea treated with Coenzyme Q10 (CoQ10) in a Streptozocin (STZ) induced diabetic rat model.

METHODS

A total of 20 male Wistar Albino rats including a group of STZ diabetic rats, diabetic rats treated with CoQ10, rats were given CoQ10 without being diabetic and a Control group were included the study. The groups were followed up for 2 months. Eye tissues were stained with Hematoxylin-Eosin (HE), Periodic Acid-Schiff (PAS), and immunohistochemical staining (IHC).

FINDINGS

The mean corneal thickness was found to be lower in the group with DM (126,62 ± 18,1) compared to the other groups. However, this decrease was found to be significant only in comparison with the control group (181,75 ± 13,87) (p = 0.000). In diabetic corneas, PAS positivity was observed in in Descemet's membrane (p = 0.021). Staining with VEGF, IL-1β, IL-6antibodies was found to be lower in the DM+CoQ10 group compared to the group with DM (p < 0.001, p < 0.001, p < 0.001).

RESULTS

We observed that diabetes increases inflammation and tendency to angiogenesis in the corneal tissue, and CoQ10 treatment reduces the corneal thickness, inflammation, and tendency to angiogenesis caused by diabetes.

Changes in Tear Meniscus Analysis of Children Who Have Type 1 Diabetes Mellitus, With and Without Vitamin D Deficiency

PURPOSE

The aim of this study was to quantitatively evaluate dry eye test parameters of pediatric patients with and without vitamin D deficiency (VDD) in type 1 diabetes mellitus.

METHODS

In this prospective cross-sectional study, the Ocular Surface Disease Index, Schirmer test, tear film breakup time, corneal staining score, and anterior segment optical coherence tomography were used to determine the dry eye test parameters of pediatric patients with type 1 diabetes mellitus (T1-DMPs) (group 1) and a healthy pediatric control group (group 2). Group 1 was divided into 2 subgroups based on their vitamin D status: group 1a, who had a VDD, and group 1b, who had vitamin D levels that were within the normal range.

RESULTS

This study compared 90 eyes of 90 pediatric T1-DMPs with 80 eyes of 80 healthy controls. The demographic characteristics of the groups were similar ( P > 0.05). The tear film breakup time, Schirmer test, corneal staining score, and values of the tear meniscus height and area were observed to have been lower in the patients in group 1a than the healthy pediatric control group, at P < 0.001. The same parameters were statistically significantly lower in the patients in group 1a when compared with group 1b ( P < 0.05 for both).

CONCLUSIONS

The tear measurements of the pediatric T1-DMPs were lower than those in the healthy pediatric control group. The accompanying VDD made this situation more pronounced.

Recombinant Human Proteoglycan 4 (rhPRG4) Downregulates TNFα-Stimulated NFκB Activity and FAT10 Expression in Human Corneal Epithelial Cells

Dry Eye Disease (DED) is a complex pathology affecting millions of people with significant impact on quality of life. Corneal inflammation, including via the nuclear factor kappa B (NFκB) pathway, plays a key etiological role in DED. Recombinant human proteoglycan 4 (rhPRG4) has been shown to be a clinically effective treatment for DED that has anti-inflammatory effects in corneal epithelial cells, but the underlying mechanism is still not understood. Our goal was to understand if rhPRG4 affects tumor necrosis factor α (TNFα)-stimulated inflammatory activity in corneal epithelial cells. We treated hTERT-immortalized corneal epithelial (hTCEpi) cells ± TNFα ± rhPRG4 and performed Western blotting on cell lysate and RNA sequencing. Bioinformatics analysis revealed that rhPRG4 had a significant effect on TNFα-mediated inflammation with potential effects on matricellular homeostasis. rhPRG4 reduced activation of key inflammatory pathways and decreased expression of transcripts for key inflammatory cytokines, interferons, interleukins, and transcription factors. TNFα treatment significantly increased phosphorylation and nuclear translocation of p65, and rhPRG4 significantly reduced both these effects. RNA sequencing identified human leukocyte antigen (HLA)-F adjacent transcript 10 (FAT10), a ubiquitin-like modifier protein which has not been studied in the context of DED, as a key pro-inflammatory transcript increased by TNFα and decreased by rhPRG4. These results were confirmed at the protein level. In summary, rhPRG4 is able to downregulate NFκB activity in hTCEpi cells, suggesting a potential biological mechanism by which it may act as a therapeutic for DED.

Role of Periostin and Nuclear Factor-κB Interplay in the Development of Diabetic Nephropathy

Diabetic nephropathy (DN) remains the most common reason for end-stage renal disease and a leading cause of kidney replacement therapy. Multifactorial pathophysiological mechanisms underlie the development of DN. Among the signalling pathways involved, nuclear factor-κB (NF-κB) plays a key role in pathogenesis triggering inflammation, oxidative stress and fibrosis. Recent evidence shows that periostin, a matricellular protein, is involved in the development of renal glomerular diseases through interaction with NF-κB signalling. The aim of the present study is to investigate the contribution of periostin and its interaction with NF-κB in DN development. To this end, we used the BTBR ob/ob mice model of diabetes type 2, and we applied transcriptomic analysis, immunostaining and methods quantifying protein and mRNA expressions. We found that increased periostin expression was correlated with decreased renal function, advanced stage renal damage and fibrosis, and NF-κB activation. Subsequently, we identified novel pathways and genes regulated by the NF-κB-periostin interaction which are involved in the mechanisms of progression of DN. Some of these genes, such as FGF1 and GDF15, have the potential to be new biomarkers and/or targets for the therapy of DN.

Effect of Aucubin-Containing Eye Drops on Tear Hyposecretion and Lacrimal Gland Damage Induced by Urban Particulate Matter in Rats

Exposure to particulate matter is a causative factor of dry eye disease. We aimed to investigate the beneficial effect of eye drops containing aucubin on dry eye disease induced by urban particulate matter (UPM). Dry eye was induced in male SD rats (6 weeks old) by topical exposure to UPM thrice a day for 5 d. Eye drops containing 0.1% aucubin or 0.5% aucubin were topically administered directly into the eye after UPM exposure for an additional 5 d. Tear secretion was evaluated using a phenol red thread tear test and corneal irregularity. The oxidative damage in the lacrimal gland was evaluated using TUNEL and immunohistochemical staining. The topical administration of aucubin significantly attenuated UPM-induced tear hyposecretion (control group: 9.25 ± 0.62 mm, UPM group: 4.55 ± 0.25 mm, 0.1% aucubin: 7.12 ± 0.58 mm, and 0.5% aucubin: 7.88 ± 0.75 mm) and corneal irregularity (control group: 0.00 ± 0.00, UPM group: 3.40 ± 0.29, 0.1% aucubin: 1.80 ± 0.27, and 0.5% aucubin: 1.15 ± 0.27). In addition, aucubin also reduced the UPM-induced apoptotic injury of lacrimal gland cells induced by oxidative stress through the increased expression of HMGB1 and RAGE. These findings indicate that the topical administration of aucubin eye drops showed a beneficial effect against UPM-induced abnormal ocular changes, such as tear hyposecretion and lacrimal gland damage. Therefore, our results reveal the pharmacological activities of aucubin in dry eye disease.

Oxidative Stress in the Protection and Injury of the Lacrimal Gland and the Ocular Surface: are There Perspectives for Therapeutics?

Oxidative stress (OS) is a major disruption in the physiology of the lacrimal functional unit (LFU). Antioxidant enzymes have dual protective activities: antioxidant and antimicrobial activities. Peroxidases have been indistinctly used as markers of the secretory activity of the LFU and implicated in the pathophysiology, diagnosis and treatment of dry eye disease (DED), even though they comprise a large family of enzymes that includes lactoperoxidase (LPO) and glutathione peroxidase (GPO), among others. Assays to measure and correlate OS with other local LFU phenomena have methodological limitations. Studies implicate molecules and reactions involved in OS as markers of homeostasis, and other studies identify them as part of the physiopathology of diseases. Despite these conflicting concepts and observations, it is clear that OS is influential in the development of DED. Moreover, many antioxidant strategies have been proposed for its treatment, including calorie restriction to nutritional supplementation. This review offers a critical analysis of the biological mechanisms, diagnostic outcomes, drug use, dietary supplements, and life habits that implicate the influence of OS on DED.

Mechanistic investigations of diabetic ocular surface diseases

With the global prevalence of diabetes mellitus over recent decades, more patients suffered from various diabetic complications, including diabetic ocular surface diseases that may seriously affect the quality of life and even vision sight. The major diabetic ocular surface diseases include diabetic keratopathy and dry eye. Diabetic keratopathy is characterized with the delayed corneal epithelial wound healing, reduced corneal nerve density, decreased corneal sensation and feeling of burning or dryness. Diabetic dry eye is manifested as the reduction of tear secretion accompanied with the ocular discomfort. The early clinical symptoms include dry eye and corneal nerve degeneration, suggesting the early diagnosis should be focused on the examination of confocal microscopy and dry eye symptoms. The pathogenesis of diabetic keratopathy involves the accumulation of advanced glycation end-products, impaired neurotrophic innervations and limbal stem cell function, and dysregulated growth factor signaling, and inflammation alterations. Diabetic dry eye may be associated with the abnormal mitochondrial metabolism of lacrimal gland caused by the overactivation of sympathetic nervous system. Considering the important roles of the dense innervations in the homeostatic maintenance of cornea and lacrimal gland, further studies on the neuroepithelial and neuroimmune interactions will reveal the predominant pathogenic mechanisms and develop the targeting intervention strategies of diabetic ocular surface complications.

State of Evidence on Oral Health Problems in Diabetic Patients: A Critical Review of the Literature

Diabetes mellitus (DM) is a global health problem, having recognized that in the next 20 years the number of diabetic patients in the world will increase to 642 million. DM exerts enormous repercussions on general health diabetic (especially derived from vascular, cardiac, renal, ocular, or neurological affectation). It entails in addition a high number of deaths directly related to the disease, as well as a high health care cost, estimated at $673 billion annually. Oral cavity is found among all the organs and systems affected in the course of DM. Important pathologies are developed with higher prevalence, such as periodontitis (PD), alterations in salivary flow, fungal infections, oral cancer, and oral potentially malignant disorders (OPMD). It has been proven that PD hinders the metabolic control of DM and that the presence of PD increases the possibility for developing diabetes. Despite the relevance of these oral pathologies, the knowledge of primary care physicians and diabetes specialists about the importance of oral health in diabetics, as well as the knowledge of dentists about the importance of DM for oral health of patients is scarce or non-existent. It is accepted that the correct management of diabetic patients requires interdisciplinary teams, including dentists. In this critical review, the existing knowledge and evidence-degree on the preventive, clinical, diagnosis, prognosis, and therapeutic aspects of oral diseases that occur with a significant frequency in the diabetic population are developed in extension.

State of Evidence on Oral Health Problems in Diabetic Patients: A Critical Review of the Literature

Diabetes mellitus (DM) is a global health problem, having recognized that in the next 20 years the number of diabetic patients in the world will increase to 642 million. DM exerts enormous repercussions on general health diabetic (especially derived from vascular, cardiac, renal, ocular, or neurological affectation). It entails in addition a high number of deaths directly related to the disease, as well as a high health care cost, estimated at $673 billion annually. Oral cavity is found among all the organs and systems affected in the course of DM. Important pathologies are developed with higher prevalence, such as periodontitis (PD), alterations in salivary flow, fungal infections, oral cancer, and oral potentially malignant disorders (OPMD). It has been proven that PD hinders the metabolic control of DM and that the presence of PD increases the possibility for developing diabetes. Despite the relevance of these oral pathologies, the knowledge of primary care physicians and diabetes specialists about the importance of oral health in diabetics, as well as the knowledge of dentists about the importance of DM for oral health of patients is scarce or non-existent. It is accepted that the correct management of diabetic patients requires interdisciplinary teams, including dentists. In this critical review, the existing knowledge and evidence-degree on the preventive, clinical, diagnosis, prognosis, and therapeutic aspects of oral diseases that occur with a significant frequency in the diabetic population are developed in extension.

State of Evidence on Oral Health Problems in Diabetic Patients: A Critical Review of the Literature

Diabetes mellitus (DM) is a global health problem, having recognized that in the next 20 years the number of diabetic patients in the world will increase to 642 million. DM exerts enormous repercussions on general health diabetic (especially derived from vascular, cardiac, renal, ocular, or neurological affectation). It entails in addition a high number of deaths directly related to the disease, as well as a high health care cost, estimated at $673 billion annually. Oral cavity is found among all the organs and systems affected in the course of DM. Important pathologies are developed with higher prevalence, such as periodontitis (PD), alterations in salivary flow, fungal infections, oral cancer, and oral potentially malignant disorders (OPMD). It has been proven that PD hinders the metabolic control of DM and that the presence of PD increases the possibility for developing diabetes. Despite the relevance of these oral pathologies, the knowledge of primary care physicians and diabetes specialists about the importance of oral health in diabetics, as well as the knowledge of dentists about the importance of DM for oral health of patients is scarce or non-existent. It is accepted that the correct management of diabetic patients requires interdisciplinary teams, including dentists. In this critical review, the existing knowledge and evidence-degree on the preventive, clinical, diagnosis, prognosis, and therapeutic aspects of oral diseases that occur with a significant frequency in the diabetic population are developed in extension.

Revealing the Angiopathy of Lacrimal Gland Lesion in Type 2 Diabetes

For a better understanding of diabetic angiopathy (DA), the potential biomarkers in lacrimal DA and its potential mechanism, we evaluated the morphological and hemodynamic alterations of lacrimal glands (LGs) in patients with type 2 diabetes and healthy counterparts by color Doppler flow imaging (CDFI). We further established a type 2 diabetic mice model and performed hematoxylin-eosin (HE) staining, immunofluorescence staining of CD31, RNA-sequencing analysis, and connectivity map (CMap) analysis. We found atrophy and ischemia in patients with type 2 diabetes and mice models. Furthermore, we identified 846 differentially expressed genes (DEGs) between type 2 diabetes mellitus (T2DM) and vehicle mice by RNA-seq. The gene ontology (GO) analysis indicated significant enrichment of immune system process, regulation of blood circulation, apoptotic, regulation of secretion, regulation of blood vessel diameter, and so on. The molecular complex detection (MCODE) showed 17 genes were involved in the most significant module, and 6/17 genes were involved in vascular disorders. CytoHubba revealed the top 10 hub genes of DEGs, and four hub genes (App, F5, Fgg, and Gas6) related to vascular regulation were identified repeatedly by MCODE and cytoHubba. GeneMANIA analysis demonstrated functions of the four hub genes above and their associated molecules were primarily related to the regulation of circulation and coagulation. CMap analysis found several small molecular compounds to reverse the altered DEGs, including disulfiram, bumetanide, genistein, and so on. Our outputs could empower the novel potential targets to treat lacrimal angiopathy, diabetes dry eye, and other diabetes-related diseases.

Modulation of Oxidative Stress and Inflammation in the Aged Lacrimal Gland

Inflammation and oxidative stress accompany aging. This study investigated the interplay between oxidative stress and inflammation in the lacrimal gland. C57BL/6 mice were used at 2 to 3, 12, and 24 months of age. Nuclear factor erythroid derived-2-related factor 2 (Nrf2)^-/- and corresponding wild-type mice were used at 2 to 3 and 12 to 13 months of age. A separate group of 15.5 to 17 months of age C57BL/6 mice received a diet containing an Nrf2 inducer (Oltipraz) for 8 weeks. Aged C57BL/6 lacrimal glands showed significantly greater lymphocytic infiltration, higher levels of MHC II, IFN-γ, IL-1β, TNF-α, and cathepsin S (Ctss) mRNA transcripts, and greater nitrotyrosine and 4-hydroxynonenal protein. Young Nrf2^-/- mice showed an increase in IL-1β, IFN-γ, MHC II, and Ctss mRNA transcripts compared with young wild-type mice and greater age-related changes at 12 to 13 months of age. Oltipraz diet significantly decreased nitrotyrosine and 4-hydroxynonenal and decreased the expression of IL-1β and TNF-α mRNA transcripts, while decreasing the frequency of CD45⁺CD4⁺ cells in lacrimal glands and significantly increasing conjunctival goblet cell density compared with a standard diet. The findings provide novel insight into the development of chronic, low-grade inflammation and oxidative stress in age-related dry eye. New therapies targeting oxidative stress pathways will be valuable in treating age-related dry eye.

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.

Alterations of Tear Film and Ocular Surface in Children with Type 1 Diabetes Mellitus

Purpose: To investigate whether diabetes mellitus (DM) affects ocular surface of children with well-controlled type 1 DM.Methods: Sixty-five diabetic patients and 55 age-matched controls enrolled to study. Detailed ocular surface assessment including, ocular surface disease index (OSDI) questionnaire, tear film break-up time (TBUT) analysis, Schirmer test, and conjunctival impression cytologic analysis were performed.Results: Schirmer test and TBUT results were significantly lower in DM group than controls (p = 0.001, for all). OSDI scores of all participants were within normal range. Impression cytology analysis showed grade 0 changes in all participants and there was no difference between groups for goblet cell density (p > 0.05). The TBUT results were significantly associated with duration of DM (r = -0.309, p = 0.036).Conclusion: Diabetic children without symptoms, signs, and definite diagnosis of dry eye still had lower TBUT and Schirmer test results than controls; however, impression cytology analysis was similar in both groups.

What Makes Cornea Immunologically Unique and Privileged? Mechanistic Clues from a High-Resolution Proteomic Landscape of the Human Cornea

Success rates of corneal transplantation are particularly high owing to its unique, innate immune privilege derived from a phenomenon known as Anterior Chamber-Associated Immune Deviation (ACAID). Of note, cornea is a transparent, avascular structure that acts as a barrier along with sclera to protect the eye and contributes to optical power. Molecular and systems biology mechanisms underlying ACAID and the immunologically unique and privileged status of cornea are not well known. We report here a global unbiased proteomic profiling of the human cornea and the identification of 4824 proteins, the largest catalog of human corneal proteins identified to date. Moreover, signaling pathway analysis revealed enrichment of spliceosome, phagosome, lysosome, and focal adhesion pathways, thereby demonstrating the protective functions of corneal proteins. We observed an enrichment of neutrophil-mediated immune response processes in the cornea as well as proteins belonging to the complement and ER-Phagosome pathways that are suggestive of active immune and inflammatory surveillance response. This study provides a key expression map of the corneal proteome repertoire that should enable future translational medicine studies on the pathological conditions of the cornea and the mechanisms by which cornea immunology are governed. Molecular mechanisms of corneal immune privilege have broad relevance to understand and anticipate graft rejection in the field of organ transplantation.

Effects of Type 2 Diabetes Mellitus on Gene Expressions of Mouse Meibomian Glands

Purpose: Type 2 Diabetes mellitus (DM) is a major health problem and its ocular complications like orbital infections, cataract and diabetic retinopathy cause blindness. Meibomian gland (MG) dysfunction and dry eye disease are also important ocular complications of type 2 DM but not enough research has been conducted on these complications. Our hypothesis suggests type 2 DM can alter significant gene expressions of MG. In our study, MGs of leptin-deficient spontaneous diabetic and non-diabetic mice were extracted, and gene expression profiles were analyzed with microarray technology.Methods: Mice were divided into two groups; nine Lep ^b/ob spontaneous diabetic mice as type 2 DM group and nine non-diabetic Balb/c mice as controls. Blood glucose levels, tearfilm break-up time and fluorescein scores were measured in both two groups for 12 weeks. MGs were dissected and RNAs were isolated for microarray gene expression analysis. We filtered probes with standard deviation of more than 0.1 and we used 40452 of 45281 probes for processing. We performed fold change analysis and identified which genes are affected, and we analyzed the impact of genes on proteins, pathways and gene ontologies by using various databases.Results: We observed 172 up-regulated and 118 down-regulated genes in type 2 diabetic mice when compared to non-diabetic mice. Interestingly, expression of collagen type I, integrin beta-I binding protein-I, pyruvate dehydrogenase kinase, TNF receptor genes up-regulated with DM; on the other hand, IL-33, cholecystokinin, plasminogen activator, IL-1 and serine peptidase inhibitor genes down-regulated significantly. Also, we have seen a significant decrease in WNT signaling and pentose phosphate pathways-related genes.Conclusion: Our data show these changes in gene expression caused by endocrine and immune mechanisms of type 2 DM which result disrupted homeostasis of epithelial cells of MG. Increased expressions of apoptosis and inflammation-related genes and their effects on related pathways have proven that MGs were negatively affected by type-2 DM.

The impact of hyperglycemia on the corneal epithelium: Molecular mechanisms and insight

Type 2 Diabetes Mellitus (T2DM) is reaching epidemic levels worldwide and with it, there is a significant increase in complications associated with the disease. T2DM affects virtually all organ systems including the eye. While frequently overlooked, diabetic keratopathy is the most common ocular complication of diabetes and can manifest in mild to severe forms, the latter of which poses a major threat to vision. As the initial barrier between the environment and the eye, the corneal epithelium functions in innate immune defense. Compromise of this barrier may predispose the cornea to infection and can hinder the refractive capabilities of the eye. The clinical burden in patients with diabetic keratopathy lies primarily in the inability of the corneal epithelium to repair damage and maintain its tight barrier function. Current therapies for diabetic keratopathy are supportive, centering on the prevention of infection and promotion of an optimal healing environment. With no clear disease-modifying agent identified as of yet, a thorough understanding of the pathophysiology that underlies the development of diabetic keratopathy at the cellular level is critical to identify and develop potential therapeutic agents capable of promoting corneal re-epithelialization to accelerate the wound healing process. The focus of this review is to examine what is known regarding the cellular and molecular mechanisms needed to maintain epithelial homeostasis and how it goes awry in diabetes.

Diabetes and Phacoemulsification Cataract Surgery: Difficulties, Risks and Potential Complications

Diabetes mellitus is one of the most prevalent chronic diseases worldwide. Diabetic patients are at risk of developing cataract and present for surgery at an earlier age than non-diabetics. The aim of this study was to review the problems associated with cataract surgery in a diabetic patient. Corneal complications in diabetic patients include delayed wound healing, risk of developing epithelial defects or recurrent erosions due to the impairment of epithelial basement membranes and epithelial-stromal interactions. Diabetic patients present lower endothelial cell density and their endothelium is more susceptible to trauma associated with cataract surgery. A small pupil is common in diabetic patients making cataract surgery technically challenging. Finally diabetic patients have an increased risk for developing postoperative pseudophakic cystoid macular edema, posterior capsule opacification or endophthalmitis. In patients with pre-proliferative or proliferative diabetic retinopathy, diabetic macular edema or iris neovascularization adjunctive therapy such as an intravitreal anti-vascular endothelial growth factor injection, can inhibit exacerbation related to cataract surgery.

Diabetes mellitus is associated with dry eye syndrome: a meta-analysis

BACKGROUND

Dry eye is the most common eye disorder of tears and ocular surface. However, the extent to which diabetes mellitus may confer risk of dry eye remains uncertain. The aim of this study was to perform a meta-analysis that synthesizes the association between diabetes mellitus and dry eye.

METHODS

Case-control studies were selected from the Medline, Embase, Cochrane database from January 2000 to March 2018. Two reviewers screened potential studies, and eligible studies were included according to keywords and predefined criteria. We calculated the overall risk estimates by using a fixed-effect model or a random-effects model in relation to heterogeneity.

RESULTS

A total of four studies were included in our meta-analysis consisting of 2,504,794 persons. Our study showed a significant association between diabetes mellitus and the risk of dry eye syndrome (OR 1.30; 95% CI 1.08-1.57; P value = 0.006). However, the heterogeneity was observed (P value < 0.001, I² = 95.2%).

CONCLUSION

Our meta-analysis suggests that diabetes mellitus has a significant association with the risk of dry eye. However, this result is limited by heterogeneity. Further prospective and concise studies are needed to confirm the association between diabetes mellitus and dry eye.

Prospective insulin-based ophthalmic delivery systems for the treatment of dry eye syndrome and corneal injuries

The presence of insulin (INS) receptors on the ocular surface (OS) and lacrimal gland (LG), and the high prevalence of dry eye syndrome (DES) and corneal lesions in diabetic patients suggest that INS is relevant for OS homeostasis and wound healing. The study aims at developing delivery systems for the topical administration of INS to the OS in order to improve INS local bioavailability and evaluate the influence of the delivery systems on DES in diabetic rats (DM) (n = 05/group). Chitosan microparticles (MP), chitosan/poloxamer gel (GEL) and MP-loaded GEL (GELMP), with or without INS were developed. Formulations were instilled into the eyes of diabetic rats (DM) for 15 days and the tear fluid volume, corneal cells morphology and cornea thickness were assessed and compared with an aqueous dispersion of INS (DISP-INS). All delivery systems had pH of about 6, osmolality suitable for topical application and positive zeta potential. The MPs with or without INS had sizes close to 4 μm, spherical morphology and INS encapsulation efficiency of 77 ± 6%. DISP-INS and GELMP-INS formulations produced tear secretion amounts significantly higher than those receiving formulations containing no INS and similar to healthy animals. Cornea surface impression cytology showed that treatment with INS-delivery systems and not DISP-INS almost normalized cells morphology. Treatment with GELMP-INS increased INS by 2.5 in the LG and eyeball as compared to the groups treated with GEL-INS and MP-INS, while treatment with DISP-INS left no traces of drug in the eye after treatment termination. GEL and GELMP containing INS were also able to normalize the thickness of the corneal epithelia. In conclusion, GELMP-INS normalized tear fluid volume, corneal thickness, protected corneal cells morphology and increased ocular bioavailability of INS, making it a promising treatment strategy for DES and corneal lesions.

Age-associated changes in human tear proteome

Background

Prevalence of many eye and ocular surface diseases increases with age. While the clinical characteristics and pathophysiologic mechanisms of these conditions are often either known or extensively studied, the effects of normal aging on tear film and ocular surface have not been as widely researched.

Methods

In order to examine the effects of aging on tear fluid proteomics, tear fluid samples were collected preoperatively from 115 subjects undergoing strabismus or refractive surgery using glass microcapillary tubes. In addition to their refractive error or strabismus, the subjects did not have any other current, known eye diseases. The non-pooled samples were analysed using NanoLC-TripleTOF implementing a sequential window acquisition of all theoretical fragment ion spectra mass spectrometry, resulting in quantified data of 849 proteins.

Results

According to correlation results, 17 tear proteins correlated significantly with increased age and many of these proteins were connected to inflammation, immune response and cell death. According to enrichment analysis, growth and survival of cells decreased while immune response and inflammation increased with aging. We also discovered several well-known, activated and inhibited upstream regulators, e.g. NF-κB, which has been previously connected to aging in numerous previous studies.

Conclusions

Overall, the results show the common age-dependent alterations in tear fluid protein profile, which demonstrate similar age-associated alterations of biological functions previously shown in other tissue and sample types.

Electronic supplementary material

The online version of this article (10.1186/s12014-019-9233-5) contains supplementary material, which is available to authorized users.

Evaluating All Potential Oral Complications of Diabetes Mellitus

Diabetes mellitus (DM) is associated with several microvascular and macrovascular complications, such as retinopathy, nephropathy, neuropathy, and cardiovascular diseases. The pathogenesis of these complications is complex, and involves metabolic and hemodynamic disturbances, including hyperglycemia, insulin resistance, dyslipidemia, hypertension, and immune dysfunction. These disturbances initiate several damaging processes, such as increased reactive oxygen species (ROS) production, inflammation, and ischemia. These processes mainly exert their damaging effect on endothelial and nerve cells, hence the susceptibility of densely vascularized and innervated sites, such as the eyes, kidneys, and nerves. Since the oral cavity is also highly vascularized and innervated, oral complications can be expected as well. The relationship between DM and oral diseases has received considerable attention in the past few decades. However, most studies only focus on periodontitis, and still approach DM from the limited perspective of elevated blood glucose levels only. In this review, we will assess other potential oral complications as well, including: dental caries, dry mouth, oral mucosal lesions, oral cancer, taste disturbances, temporomandibular disorders, burning mouth syndrome, apical periodontitis, and peri-implant diseases. Each oral complication will be briefly introduced, followed by an assessment of the literature studying epidemiological associations with DM. We will also elaborate on pathogenic mechanisms that might explain associations between DM and oral complications. To do so, we aim to expand our perspective of DM by not only considering elevated blood glucose levels, but also including literature about the other important pathogenic mechanisms, such as insulin resistance, dyslipidemia, hypertension, and immune dysfunction.

RAGE-induced changes in the proteome of alveolar epithelial cells

The receptor for advanced glycation end-products (RAGE) is a pattern recognition receptor and member of the immunoglobulin superfamily. RAGE is constitutively expressed in the distal lung where it co-localizes with the alveolar epithelium; RAGE expression is otherwise minimal or absent, except with disease. This suggests RAGE plays a role in lung physiology and pathology. We used proteomics to identify and characterize the effects of RAGE on rat alveolar epithelial (R3/1) cells. LC-MS/MS identified 177 differentially expressed proteins and the PANTHER Classification System further segregated proteins. Proteins involved in gene transcription (RNA and mRNA splicing, mRNA processing) and transport (protein, intracellular protein) were overrepresented; genes involved in a response to stimulus were underrepresented. Immune system processes and response to stimuli were downregulated with RAGE knockdown. Western blot confirmed RAGE-dependent changes in protein expression for NFκB and NLRP3 that was functionally supported by a reduction in IL-1β and phosphorylated p65. We also assessed RAGE's effect on redox regulation and report that RAGE knockdown attenuated oxidant production, decreased protein oxidation, and increased reduced thiol pools. Collectively the data suggest that RAGE is a critical regulator of epithelial cell response and has implications for our understanding of lung disease, specifically acute lung injury.

SIGNIFICANCE STATEMENT

In the present study, we undertook the first proteomic evaluation of RAGE-dependent processes in alveolar epithelial cells. The alveolar epithelium is a primary target during acute lung injury, and our data support a role for RAGE in gene transcription, protein transport, and response to stimuli. More over our data suggest that RAGE is a critical driver of redox regulation in the alveolar epithelium. The conclusions of the present work assist to unravel the molecular events that underlie the function of RAGE in alveolar epithelial cells and have implications for our understanding of RAGE signaling during lung injury. Our study was the first proteomic comparison showing the effects of RAGE activation from alveolar epithelial cells that constitutively express RAGE and these results can affect a wide field of lung biology, pulmonary therapeutics, and proteomics.

TFOS DEWS II Sex, Gender, and Hormones Report

One of the most compelling features of dry eye disease (DED) is that it occurs more frequently in women than men. In fact, the female sex is a significant risk factor for the development of DED. This sex-related difference in DED prevalence is attributed in large part to the effects of sex steroids (e.g. androgens, estrogens), hypothalamic-pituitary hormones, glucocorticoids, insulin, insulin-like growth factor 1 and thyroid hormones, as well as to the sex chromosome complement, sex-specific autosomal factors and epigenetics (e.g. microRNAs). In addition to sex, gender also appears to be a risk factor for DED. "Gender" and "sex" are words that are often used interchangeably, but they have distinct meanings. "Gender" refers to a person's self-representation as a man or woman, whereas "sex" distinguishes males and females based on their biological characteristics. Both gender and sex affect DED risk, presentation of the disease, immune responses, pain, care-seeking behaviors, service utilization, and myriad other facets of eye health. Overall, sex, gender and hormones play a major role in the regulation of ocular surface and adnexal tissues, and in the difference in DED prevalence between women and men. The purpose of this Subcommittee report is to review and critique the nature of this role, as well as to recommend areas for future research to advance our understanding of the interrelationships between sex, gender, hormones and DED.

Proteasomes in corneal epithelial cells and cultured autologous oral mucosal epithelial cell sheet (CAOMECS) graft used for the ocular surface regeneration

PURPOSE

This study focuses on characterizing proteasomes in corneal epithelial cells (CEC) and in cultured autologous oral mucosal epithelial cell sheets (CAOMECS) used to regenerate the ocular surface.

METHODS

Limbal stem cell deficiency (LSCD) was surgically induced in rabbit corneas. CAOMECS was engineered and grafted onto corneas with LSCD to regenerate the ocular surface.

RESULTS

LSCD caused an increase in inflammatory cells in the ocular surface, an increase in the formation of immunoproteasomes (IPR), and a decrease in the formation of constitutive proteasome (CPR). Specifically, LSCD-diseased CEC (D-CEC) showed a decrease in the CPR chymotrypsin-like, trypsin-like and caspase-like activities, while healthy CEC (H-CEC) and CAOMECS showed higher activities. Quantitative analysis of IPR inducible subunit (B5i, B2i, and B1i) were performed and compared to CPR subunit (B5, B2, and B1) levels. Results showed that ratios B5i/B5, B2i/B2 and B1i/B1 were higher in D-CEC, indicating that D-CEC had approximately a two-fold increase in the amount of IPR compared to CAOMECS and H-CEC. Histological analysis demonstrated that CAOMECS-grafted corneas had a re-epithelialized surface, positive staining for CPR subunits, and weak staining for IPR subunits. In addition, digital quantitative measurement of fluorescent intensity showed that the CPR B5 subunit was significantly more expressed in CAOMECS-grafted corneas compared to non-grafted corneas with LSCD.

CONCLUSION

CAOMECS grafting successfully replaced the D-CEC with oral mucosal epithelial cells with higher levels of CPR. The increase in constitutive proteasome expression is possibly responsible for the recovery and improvement in CAOMECS-grafted corneas.

The Effects of Low-Power Laser Irradiation on Inflammation and Apoptosis in Submandibular Glands of Diabetes-Induced Rats

Diabetes can lead to dysfunction of the secretory capacity in salivary glands. Activation of the receptor for advanced glycation end products (RAGE) and its ligands has been suggested to participate in chronic disorders such as diabetes and its complications. In this study, the expression of RAGE, high mobility group box 1 (HMGB1) and advanced glycation end products (AGE), as well as the effects of low-power laser irradiation (LPLI) in salivary glands of diabetic rats were evaluated, and the mechanisms involved were characterized. The expression of RAGE and HMGB1 at the protein and mRNA levels was observed in submandibular glands (SMGs) of streptozotocin-induced diabetic rats. A diode laser was applied at 660 nm, 70 mW, 20 J/cm², 0.56 J/point, with a spot area of 0.028 cm² and its in vivo effects and the pathways involved were evaluated. Immunohistochemistry and western blotting analysis were performed for inflammatory and apoptosis markers. Diabetes up-regulates HMGB1/AGE/RAGE axis gene expression in SMGs that is associated with activation of the nuclear factor kappa B (NF-κB) pathway. Interestingly, LPLI suppresses NF-κB activation induced by inflammation. LPLI also reduces diabetes-induced apoptosis. That effect was accompanied by decreased levels of Bax, and cleaved caspase 3, which were up-regulated in diabetes. Taken together, our data suggest that LPLI reduces diabetes-induced inflammation by reducing the induction of HMGB1, ultimately leading to inhibition of apoptosis in submandibular glands of diabetic rats.

Enhanced RAGE Expression in the Dorsal Root Ganglion May Contribute to Neuropathic Pain Induced by Spinal Nerve Ligation in Rats

OBJECTIVE

There is some evidence implicating receptor for advanced glycation end products (RAGE) signaling in the pathogenesis of neuropathic pain (NP). The objective was to investigate whether RAGE signaling in the dorsal root ganglion (DRG) might contribute to NP following peripheral nerve injury.

DESIGN

Experimental study before and after spinal nerve ligation (SNL) surgery.

SETTING

Caged in a controlled environment.

SUBJECTS

Male Sprague-Dawley rats.

METHODS

A SNL rat model of NP was used. Mechanical hyperalgesia was measured by the paw withdrawal threshold (PWT) to mechanical stimuli (1.4-15 g). Protein expressions of RAGE (immunofluorescence and western blotting), glial fibrillary acidic protein (GFAP; satellite glial cell [SGC] activation marker), IL-1β (ELISA), TNF-α (ELISA), and NF-κB (western blotting) in the DRG were determined. RAGE signaling was inhibited by intrathecal injection of anti-RAGE antibody.

RESULTS

After 7 days, SNL surgery reduced the PWT and upregulated the protein expression of RAGE, GFAP, NF-κB, TNF-α, and IL-1β. Intrathecal injection of RAGE-neutralizing antibody attenuated the SNL-induced mechanical hyperalgesia, activation of SGCs, and upregulation of NF-κB, TNF-α, and IL-1β in the DRG.

CONCLUSION

RAGE signaling may contribute to the pain hypersensitivity observed in the rat SNL model of NP. Although the precise mechanism remains to be established, NF-κB, TNF-α, and IL-1β likely play a role, together with the activation of SGCs.

Significance of downregulation of renal organic cation transporter (SLC47A1) in cisplatin-induced proximal tubular injury

Background/aim

To elucidate the mechanism responsible for developing acute kidney injury in patients with diabetes mellitus, we also evaluated the issue of whether advanced glycation endproducts (AGEs) influence the expressions of multi antimicrobial extrusion protein (MATE1/SLC47A1) in tubular cells.

Materials and methods

To detect changing expression of MATE1/SLC47A1 in dose- and time-dependent manners, human proximal tubular epithelial cells were incubated with AGE-aggregated-human serum albumin. As a function assay for MATE1/SLC47A1, human proximal tubular epithelial cells were incubated with cisplatin or carboplatin.

Results

On incubation with AGEs, the expressions of MATE1/SLC47A1 were decreased in tubular cells. In addition, the toxicities of cisplatin were increased in tubular cells that had been pretreated with AGEs. However, the toxicities of carboplatin were smaller than that of cisplatin in proximal tubular epithelial cells.

Conclusion

The expression of the MATE1/SLC47A1 is decreased by AGEs, which increases the risk for proximal tubular injury.

Peripheral neuropathy and tear film dysfunction in type 1 diabetes mellitus

PURPOSE

To compare tear film metrics in patients with type 1 diabetes mellitus (DM) and healthy controls and investigate the association between peripheral neuropathy and ocular surface quality.

METHODS

Dry eye symptoms were quantified in 53 patients with type 1 DM and 40 age-matched controls. Ocular examination included tear film lipid layer thickness grading, tear film stability and quantity measurement, and retinal photography. DM individuals additionally underwent a detailed neuropathy assessment.

RESULTS

Neither mean age nor dry eye symptom scores differed significantly between the DM and control groups (P = 0.12 and P = 0.33, resp.). Tear lipid thickness (P = 0.02), stability (P < 0.0001), and quantity (P = 0.01) were significantly lower in the DM group. Corneal sensitivity was also reduced in the DM group (P < 0.001) and tear film stability was inversely associated with total neuropathy score (r = -0.29, P = 0.03).

CONCLUSION

The DM group exhibited significantly reduced tear film stability, secretion, and lipid layer quality relative to the age-matched control group. The negative correlation between tear film parameters and total neuropathy score suggests that ocular surface abnormalities occur in parallel with diabetic peripheral neuropathy.

Production of reactive oxygen species in the diabetic heart. Roles of mitochondria and NADPH oxidase

Reactive oxygen species (ROS) are the main facilitators of cardiovascular complications in diabetes mellitus (DM), and the ROS level is increased in cultured cells exposed to high glucose concentrations or in diabetic animal models. Emerging evidence shows that mitochondria and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase are dominant mechanisms of ROS production in the diabetic heart. Hyperpolarization of the mitochondrial inner membrane potentials and impaired mitochondrial function promote ROS production in the mitochondria of the diabetic heart. Uncoupling proteins are upregulated and may reduce the ROS level by depolarizing the mitochondrial inner membrane potential. NADPH oxidase is another major site of ROS production and its contribution to DM-induced ROS increase has been elucidated not only in vascular smooth muscle cells and endothelial cells, but also in cardiomyocytes. Protein kinase C, angiotensin II, and advanced glycation endproducts (AGEs)/receptor for AGEs can activate NADPH oxidase. Increased intracellular calcium level mediated via the Na(+)-H(+) exchanger and subsequent activation of Ca(2+)/calmodulin-dependent protein kinase II may also activate NADPH oxidase. This review presents the current understanding of the mechanisms of ROS production, focusing especially on the roles of mitochondria and NADPH oxidase. 

The potential neuroprotection mechanism of GDNF in the 6-OHDA-induced cellular models of Parkinson's Disease

The glial cell line-derived neurotrophic factor (GDNF) potential as a therapeutic agent for the treatment of Parkinson's Disease (PD) has been extensively explored. However, the mechanism of the GDNF neuroprotective effects is still unclear. In this study, the neuroprotective mechanism of the GDNF in the PD cellular models, which was obtained by the 6-hydroxydopamine (6-OHDA)-induced dopaminergic (DA) cell line MN9D damage was investigated by microarray. Interestingly, 54 constitutively increased or decreased genes were detected, 17 of which have not been reported previously. The expression of 5 up-regulated and 5 down-regulated genes which displayed the most obvious changes compared to the no GDNF treatment cells and was previously proven to be related to cell survival was validated by real-time PCR and western blot. Moreover, the up-regulated gene Ager and down-regulated gene Ccnl2 which were related to the PI-3K/Akt signaling pathway, but not researched in the neuron-cells, were investigated by overexpression and RNA interference. Overexpression of Ager or knockdown the expression of Ccnl2 decreased the damage to MN9D cells caused by 6-OHDA and reduced their apoptosis. All these results suggested that the protective effects of the GDNF on the 6-OHDA damaged MN9D cells could be understood by enhancing the expression of the apoptosis inhibiting genes and decreasing the expression of the apoptosis promoting genes. Thus, this study might provide a number of specific candidates and potential targets to investigate the protective mechanism of GDNF in DA neurons.

Advanced glycation end products induce human corneal epithelial cells apoptosis through generation of reactive oxygen species and activation of JNK and p38 MAPK pathways

Advanced Glycation End Products (AGEs) has been implicated in the progression of diabetic keratopathy. However, details regarding their function are not well understood. In the present study, we investigated the effects of intracellular reactive oxygen species (ROS) and JNK, p38 MAPK on AGE-modified bovine serum albumin (BSA) induced Human telomerase-immortalized corneal epithelial cells (HUCLs) apoptosis. We found that AGE-BSA induced HUCLs apoptosis and increased Bax protein expression, decreased Bcl-2 protein expression. AGE-BSA also induced the expression of receptor for advanced glycation end product (RAGE). AGE-BSA-RAGE interaction induced intracellular ROS generation through activated NADPH oxidase and increased the phosphorylation of p47phox. AGE-BSA induced HUCLs apoptosis was inhibited by pretreatment with NADPH oxidase inhibitors, ROS quencher N-acetylcysteine (NAC) or neutralizing anti-RAGE antibodies. We also found that AGE-BSA induced JNK and p38 MAPK phosphorylation. JNK and p38 MAPK inhibitor effectively blocked AGE-BSA-induced HUCLs apoptosis. In addition, NAC completely blocked phosphorylation of JNK and p38 MAPK induced by AGE-BSA. Our results indicate that AGE-BSA induced HUCLs apoptosis through generation of intracellular ROS and activation of JNK and p38 MAPK pathways.

Protective effect of short-term genistein supplementation on the early stage in diabetes-induced renal damage

Hyperglycemia-induced oxidative stress has been concerned in the development of diabetic nephropathy (DN), which may cause kidney damage associated with inflammation and fibrosis. This study has been conducted to investigate the role of genistein supplementation in an acute DN state. Mice with FBG levels more than 250 mg/dL after alloxan injection (single i.p., 150 mg/kg) were considered as diabetic. Diabetic mice (DM) were further subdivided according to their FBG levels, medium-high FBG (DMMH < 450 mg/dL) and high FBG (DMH; 450 mg/dL) and were administrated by an AIG-93G diet supplemented with different doses of genistein (0, 0.025 or 0.1%). After 2 weeks' treatment, the levels of kidney malondialdehyde (MDA), blood urea nitrogen (BUN), and plasma creatinine and lipid profiles, as well as oxidative stress and inflammation-related markers, were measured (P < 0.05). Genistein supplementation improved levels of FBG in the DMMH groups, but not in the DMH group, regardless of the treatment dose. Moreover, the supplementation attenuated kidney oxidative stress indicated by MDA, BUN, and plasma creatinine. In addition, genistein treatment decreased inflammatory markers such as nuclear factor kappa B (p65), phosphorylated inhibitory kappa B alpha, C-reactive protein, monocyte chemotactic protein-1, cyclooxygenase-2, and tumor necrosis factor-alpha and improved oxidative stress markers (nuclear-related factor E2, heme oxygenase-1, glutathione peroxidase, and superoxide dismutase isoforms) in treatment groups, regardless of the genistein treatment dose. Furthermore, genistein supplementation inhibited the fibrosis-related markers (protein kinase C, protein kinase C-beta II, and transforming growth factor-beta I) in the DN state. However, 0.1% genistein supplementation in diabetes with high FBG levels selectively showed a preventive effect on kidney damage. These results suggest that genistein might be a good protective substance for DN through regulation of oxidative stress and inflammation. In particular, genistein is more efficient in diabetes patients with medium-high blood glucose levels. Finally, it is required to establish the beneficial dosage of genistein according to blood glucose levels.

Nuclear Factor-κB: central regulator in ocular surface inflammation and diseases

The nuclear factor-κB (NF-κB) is a key transcription factor pathway that is responsible for many key biological processes, such as inflammation, apoptosis, stress response, corneal wound healing, angiogenesis, and lymphangiogenesis. Numerous recent studies have investigated NF-κB in the context of ocular surface disorders, including chemical injury, ultraviolet radiation-induced injury, microbial infections, allergic eye diseases, dry eye, pterygium, and corneal graft rejection. The purpose this article is to summarize key findings with regard to the pathways regulating NF-κB and processes governed by the NF-κB pathway. In the innate defense system, NF-κB is involved in signaling from the toll-like receptors 2, 3, 4, 5 and 7, which are expressed in conjunctival, limbal, and corneal epithelial cells. These determine the ocular responses to infections, such as those caused by Pseudomonas aeruginosa, Staphylococcus aureus, adenovirus, and herpes simplex-1 virus. Natural angiogenic inhibitors enhance NF-κB, and this may occur through the mitogen-activated protein kinases and peroxisome proliferator-activated receptor γ. In alkali injury, inhibition of NF-κB can reduce corneal angiogenesis, suggesting a possible therapeutic strategy. The evaluation of NF-κB inhibitors in diseases is also discussed, including emodin, besifloxacin, BOL-303242-X (mapracorat), thymosin-β4, epigallocatechin gallate, Perilla frutescens leaf extract and IKKβ-targeting short interfering RNA.

Proteomic profiling of human retinal pigment epithelium exposed to an advanced glycation-modified substrate

PURPOSE

The retinal pigment epithelium (RPE) and underlying Bruch's membrane undergo significant modulation during ageing. Progressive, age-related modifications of lipids and proteins by advanced glycation end products (AGEs) at this cell-substrate interface have been implicated in RPE dysfunction and the progression to age-related macular degeneration (AMD). The pathogenic nature of these adducts in Bruch's membrane and their influence on the overlying RPE remains unclear. This study aimed to identify alterations in RPE protein expression in cells exposed to AGE-modified basement membrane (AGE-BM), to determine how this "aged" substrate impacts RPE function and to map the localisation of identified proteins in ageing retina.

METHODS

Confluent ARPE-19 monolayers were cultured on AGE-BM and native, non-modified BM (BM). Following 28-day incubation, the proteome was profiled using 2-dimensional gel electrophoresis (2D), densitometry and image analysis was employed to map proteins of interest that were identified by electrospray ionisation mass spectrometry (ESI MS/MS). Immunocytochemistry was employed to localise identified proteins in ARPE-19 monolayers cultured on unmodified and AGE-BM and to analyze aged human retina.

RESULTS

Image analysis detected altered protein spot densities between treatment groups, and proteins of interest were identified by LC ESI MS/MS which included heat-shock proteins, cytoskeletal and metabolic regulators. Immunocytochemistry revealed deubiquitinating enzyme ubiquitin carboxyterminal hydrolase-1 (UCH-L1), which was upregulated in AGE-exposed RPE and was also localised to RPE in human retinal sections.

CONCLUSIONS

This study has demonstrated that AGE-modification of basement membrane alters the RPE proteome. Many proteins are changed in this ageing model, including UCHL-1, which could impact upon RPE degradative capacity. Accumulation of AGEs at Bruch"s membrane could play a significant role in age-related dysfunction of the RPE.

Cannabinoid 1 receptor activation contributes to vascular inflammation and cell death in a mouse model of diabetic retinopathy and a human retinal cell line

AIMS/HYPOTHESIS

Recent studies have demonstrated that cannabinoid-1 (CB(1)) receptor blockade ameliorated inflammation, endothelial and/or cardiac dysfunction, and cell death in models of nephropathy, atherosclerosis and cardiomyopathy. However the role of CB(1) receptor signalling in diabetic retinopathy remains unexplored. Using genetic deletion or pharmacological inhibition of the CB(1) receptor with SR141716 (rimonabant) in a rodent model of diabetic retinopathy or in human primary retinal endothelial cells (HREC) exposed to high glucose, we explored the role of CB(1) receptors in the pathogenesis of diabetic retinopathy.

METHODS

Diabetes was induced using streptozotocin in C57BL/6J Cb(1) (also known as Cnr1)(+/+) and Cb(1)(-/-) mice aged 8 to 12 weeks. Samples from mice retina or HREC were used to determine: (1) apoptosis; (2) activity of nuclear factor kappa B, intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), poly (ADP-ribose) polymerase and caspase-3; (3) content of 3-nitrotyrosine and reactive oxygen species; and (4) activation of p38/Jun N-terminal kinase/mitogen-activated protein kinase (MAPK).

RESULTS

Deletion of CB(1) receptor or treatment of diabetic mice with CB(1) receptor antagonist SR141716 prevented retinal cell death. Treatment of diabetic mice or HREC cells exposed to high glucose with SR141716 attenuated the oxidative and nitrative stress, and reduced levels of nuclear factor κB, ICAM-1 and VCAM-1. In addition, SR141716 attenuated the diabetes- or high glucose-induced pro-apoptotic activation of MAPK and retinal vascular cell death.

CONCLUSIONS/INTERPRETATION

Activation of CB(1) receptors may play an important role in the pathogenesis of diabetic retinopathy by facilitating MAPK activation, oxidative stress and inflammatory signalling. Conversely, CB(1) receptor inhibition may be beneficial in the treatment of this devastating complication of diabetes.

Protection against advanced glycation end products and oxidative stress during the development of diabetic keratopathy by KIOM-79

OBJECTIVES

KIOM-79 is a mixture of 80% ethanol extracts of parched Puerariae radix, gingered Magnoliae cortex, Glycyrrhizae radix and Euphorbiae radix. The preventive effect of KIOM-79 on the development of diabetic keratopathy has been investigated.

METHODS

Seven-week-old male Zucker diabetic fatty (ZDF) rats were treated with KIOM-79 (50 mg/kg body weight) once a day orally for 13 weeks. The thickness of the cornea was measured and the extent of corneal cell death was detected by a terminal deoxynucleotidyl transferase dUTP nick-end labelling assay. The expression of advanced glycation end products (AGEs), 8-hydroxydeoxyguanosine, nuclear factor-kappaB (NF-κB), Bax and Bcl-2 were evaluated in corneal tissues.

KEY FINDINGS

The administration of KIOM-79 prevented corneal oedema and apoptotic cell death of corneal cells. The accumulation of AGE in corneal tissues was reduced in ZDF rats treated with KIOM-79. Moreover, KIOM-79 attenuated oxidative DNA damage, NF-κB activation and Bax overexpression in the cornea.

CONCLUSIONS

The results suggested that KIOM-79 exhibited corneal protective properties by not only reducing oxidative stress but inhibiting the AGEs/NF-κB downstream signal pathway during the development of diabetic keratopathy.

Involvement of advanced glycation end products, oxidative stress and nuclear factor-kappaB in the development of diabetic keratopathy

BACKGROUND

The purpose of the experiment reported here was to assess the involvement of advanced glycation end products (AGEs), oxidative stress, and nuclear factor kappa-B (NF-κB) activation in the development of diabetic keratopathy.

METHODS

Diabetes was induced by intraperitoneal streptozotocin injection in male Sprague-Dawley rats. The thickness of the cornea was measured. Apoptosis was detected by TUNEL assay and western blot for caspase-3. The expression of AGEs and 8-hydroxydeoxyguanosine (8-OHdG) were studied by immunohistochemistry in corneal tissues of normoglycaemic and diabetic rats. NF-κB activation was evaluated by electrophoretic mobility shift assay and southwestern histochemistry.

RESULTS

Corneal edema was observed in diabetic rats. The thickness of cornea was higher in diabetic than in control rats. AGEs were accumulated in corneal tissues. 8-OHdG and NF-κB were identified in corneal epithelium, stroma and endothelium, and its expressions were greater in diabetic than in those of control rats. Diabetes induces significant alterations in rat corneal tissue structure.

CONCLUSIONS

The higher expression of AGE, 8-OHdG and NF-κB in corneal tissues of diabetic rats suggests that these factors are involved in apoptosis and in subsequent corneal alterations related to diabetic keratopathy.

KIOM-79 Prevents Lens Epithelial Cell Apoptosis and Lens Opacification in Zucker Diabetic Fatty Rats

Damage of lens epithelial cells (LECs) has been implicated in cataract formation. The aim of this study was to investigate the protective effect of KIOM-79, a combination of four plant extracts, on LECs. We examined the levels of advanced glycation end products (AGEs), nuclear factor-kappaB (NF-κB) activation and inducible nitric oxide synthase (iNOS) expression in LECs during cataract development using the Zucker diabetic fatty (ZDF) rat, an animal model of type 2 diabetes. KIOM-79 was orally administered by gavage to ZDF rats once a day for 13 weeks. Apoptosis was detected by TUNEL assay, and NF-κB activation and iNOS expression were studied by southwestern histochemistry and immunohistochemistry, respectively. In diabetic cataractous lenses, TUNEL-positive LECs were markedly increased 20-fold, and AGEs were highly accumulated (2.7-fold) in LECs. In addition, both NF-κB activation, and iNOS expression were significantly enhanced 3- to 5-fold, respectively, compared to levels found in normal ZL rats. However, the administration of KIOM-79 delayed the development of diabetic cataracts and prevented LEC apoptosis (70%) through the inhibition of AGEs, NF-κB-activation and iNOS expression. These observations suggest that KIOM-79 is useful in inhibiting diabetic cataractogenesis and acts through an antiapoptotic mechanism to protect LECs from injury.