Plasma polymer surface modified expanded polytetrafluoroethylene promotes epithelial monolayer formation in vitro and can be transplanted into the dystrophic rat subretinal space.

The aim of this study was to evaluate whether the surface modification of expanded polytetrafluoroethylene (ePTFE) using an n-heptylamine (HA) plasma polymer would allow for functional epithelial monolayer formation suitable for subretinal transplant into a non-dystrophic rat model. Freshly isolated iris pigment epithelial (IPE) cells from two rat strains (Long Evans [LE] and Dark Agouti [DA]) were seeded onto HA, fibronectin-coated n-heptylamine modified (F-HA) and unmodified ePFTE and fibronectin-coated tissue culture (F-TCPS) substrates. Both F-HA ePTFE and F-TCPS substrates enabled functional monolayer formation with both strains of rat. Without fibronectin coating, only LE IPE formed a monolayer on HA-treated ePTFE. Functional assessment of both IPE strains on F-HA ePTFE demonstrated uptake of POS that increased significantly with time that was greater than control F-TCPS. Surgical optimization using Healon GV and mixtures of Healon GV: phosphate buffered saline (PBS) to induce retinal detachment demonstrated that only Healon GV:PBS allowed F-HA ePTFE substrates to be successfully transplanted into the subretinal space of Royal College of Surgeons rats, where they remained flat beneath the neural retina for up to 4 weeks. No apparent substrate-induced inflammatory response was observed by fundus microscopy or immunohistochemical analysis, indicating the potential of this substrate for future clinical applications.

Possible Modifying Effect of Hemoglobin A1c on Genetic Susceptibility to Severe Diabetic Retinopathy in Patients With Type 2 Diabetes.

Purpose: Glycemic control has been recognized as an important modifiable risk factor for diabetic retinopathy (DR). Whether hemoglobin A1c (HbA1c), as an indicator of glycemic control, could modify the genetic susceptibility to severe DR remains to be investigated. This study aimed to investigate whether HbA1c could modulate the genetic susceptibility to severe DR in Chinese patients with type 2 diabetes. Methods: A total of 3,093 Chinese individuals with type 2 diabetes were included in the cross-sectional case-control study: 1,051 with sight-threatening DR (STDR) and 2,042 without STDR. Sixty-nine top-ranked single nucleotide polymorphisms (SNPs) identified from previous genome-wide association studies were examined for their associations with STDR and proliferative DR as a subgroup analysis. SNPs showing suggestive associations with DR were examined in the stratified analysis by dichotomized HbA1c (<7% vs. ≥7%). An interaction analysis was performed by including an interaction term of SNP × HbA1c in the regression model. Results: Four SNPs showed suggestive associations with STDR. In the stratified analysis, patients with adequate glycemic control (HbA1c <7%) had a 42% lower risk of STDR for carrying each additional protective C allele of COL5A1 rs59126004 (P = 1.76 × 10-4; odds ratio, 0.58; 95% confidence interval, 0.44-0.77). rs59126004 demonstrated a significant interaction with dichotomized HbA1c on the risk of STDR (Pinteraction = 1.733 × 10-3). In the subgroup analysis for proliferative DR, the protective effect of rs59126004 was even more pronouncedly demonstrated (P = 8.35 × 10-5; odds ratio, 0.37; 95% confidence interval, 0.22-0.60) and it showed similar interactions with dichotomized HbA1c (Pinteraction = 1.729 × 10-3). Conclusions: Our data provided evidence for possible interactions between HbA1c and COL5A1 rs59126004 on the risk of severe DR. These findings may provide new insight into the pathophysiologic mechanism of DR.

Awareness of diabetic retinopathy and its association with attendance for systematic screening at the public primary care setting: a cross-sectional study in Hong Kong.

OBJECTIVE: To assess the association between awareness of diabetic retinopathy (DR) and actual attendance for DR screening. DESIGN: Cross-sectional study. SETTING: Two public general outpatient clinics. PARTICIPANTS: The subjects were people with diabetes mellitus (DM) who participated in a randomised controlled trial, set up in 2008, to test the impact of a copayment on attendance for DR screening. PRIMARY AND SECONDARY OUTCOME MEASURES: The subjects' awareness of DR was evaluated using a structured questionnaire conducted via a telephone interview. The attendance for screening was from the actual attendance data. Association between awareness and attendance for screening was determined using multivariate logistic regression model and was reported as ORs. RESULTS: A total of 2593 participants completed the questionnaire. A total of 42.9% (1113/2593) said they would worry if they had any vision loss and 79.6% (2063/2593) knew that DM could cause blindness. Only 17.5% (453/2593) knew that treatment was available for DR and 11.5% (297/2593) knew that early DR could be asymptomatic. The importance of having a regular eye examination was acknowledged by 75.7% (1964/2593), but 34% (881/2593) did not know how frequently their eyes should be examined. Worry about vision loss (OR=1.72, P<0.001), awareness of the importance of regular eye examination (OR=1.83, P=0.002) and awareness of the frequency of eye examinations ('every year' (OR=2.64, P<0.001) or 'every 6 months' (OR=3.27, P<0.001)) were the most significant factors associated with attendance. CONCLUSIONS: Deficits in knowledge of DR and screening were found among subjects with DM, and three awareness factors were associated with attendance for screening. These factors could be targeted for future interventions.

Inhibition of NUCKS Facilitates Corneal Recovery Following Alkali Burn.

Corneal wound healing involves a complex cascade of cytokine-controlled cellular events, including inflammatory and angiogenesis responses that are regulated by transcriptional chromatin remodeling. Nuclear Ubiquitous Casein and cyclin-dependent Kinase Substrate (NUCKS) is a key chromatin modifier and transcriptional regulator of metabolic signaling. In this study, we investigated the role of NUCKS in corneal wound healing by comparing its effects on corneal alkali burn in NUCKS knockout (NKO) and NUCKS wild-type (NWT) mice. Our data showed that following alkali-injury, inhibition of NUCKS (NKO) accelerated ocular resurfacing and suppressed neovascularization; the cytokine profile of alkali burned corneas in NKO mice showed suppressed expression of inflammation cytokines (IL1A &IL1B); upregulated expression of antiangiogenic factor (Pigment Epithelium-derived Factor; PEDF); and downregulated expression of angiogenic factor (Vascular Endothelial Growth Factor, VEGF); in vitro, following LPS-induced NFκB activation, NKO corneal cells showed reduced expression of IL6, IP10 and TNFα. In vitro, corneal epithelial cells showed reduced NF-κb activation on silencing of NUCKS and corresponding NFκB-mediated cytokine expression was reduced. Here, we illustrate that inhibition of NUCKS played a role in cytokine modulation and facilitated corneal recovery. This reveals a potential new effective strategy for ocular burn treatment.

Impact of Genetic Loci Identified in Genome-Wide Association Studies on Diabetic Retinopathy in Chinese Patients With Type 2 Diabetes.

PURPOSE: Diabetic retinopathy (DR) is a common microvascular complication of type 2 diabetes (T2DM). Genome-wide association studies (GWAS) had identified novel DR-susceptibility genetic variants in various populations. We examined the associations of these DR-associated single nucleotide polymorphisms (SNPs) with severe DR in a Chinese T2DM cohort. METHODS: Cross-sectional case-control studies on sight-threatening DR (STDR) and proliferative DR (PDR) were performed. We genotyped 38 SNPs showing top association signals with DR in previous GWAS in 567 STDR cases, including 309 with PDR and 1490 non-DR controls. Multiple logistic regression models with adjustment for conventional risk factors, including age, sex, duration of diabetes, and presence of hypertension, were employed. RESULTS: The strongest association was found at INSR rs2115386, an intronic SNP of INSR: Padjusted = 9.13 × 10-4 (odds ratio [OR],1.28; 95% confidence interval [95%CI], 1.11-1.48) for STDR, and Padjusted= 1.12 × 10-4 (OR [95%CI],1.44 [1.20-1.74]) for PDR. rs599019 located downstream of COLEC12 (Padjusted = 0.019; OR [95%CI],1.19 [1.03-1.38]) and rs4462262 located at an intergenic region between ZWINT and MRPS35P3 (Padjusted = 0.041; OR [95%CI],1.38[1.01-1.89]) also were significantly associated with STDR, but not with PDR alone. On the other hand, MYT1L-LOC729897 rs10199521 (Padjusted = 0.022; OR [95%CI],1.25 [1.03-1.51]) and API5 rs899036 (Padjusted = 0.049; OR [95%CI],1.36 [1.00-1.85]) showed significant independent associations only with PDR. Similar results were obtained when hemoglobin A1c also was included in the adjustment models. CONCLUSIONS: We demonstrated the significant and independent associations of several GWAS-identified SNPs with DR in Chinese T2DM patients with severe DR. The findings on INSR rs2115386 are supportive of the role of insulin resistance, or the compensatory hyperinsulinemia, in the pathogenesis of DR.

Distribution of Triamcinolone Acetonide after Intravitreal Injection into Silicone Oil-Filled Eye.

There is increasing use of the vitreous cavity as a reservoir for drug delivery. We study the intraocular migration and distribution of triamcinolone acetonide (TA) after injection into silicone oil tamponade agent during and after vitrectomy surgery ex vivo (pig eye) and in vitro (glass bottle). For ex vivo assessment, intraocular migration of TA was imaged using real-time FLASH MRI scans and high-resolution T2W imaging and the in vitro model was monitored continuously with a video camera. Results of the ex vivo experiment showed that the TA droplet sank to the interface of silicone oil and aqueous almost immediately after injection and remained inside the silicone oil bubble for as long as 16 minutes. The in vitro results showed that, after the shrinkage of the droplet, TA gradually precipitated leaving only a lump of whitish crystalline residue inside the droplet for about 100 minutes. TA then quickly broke the interface and dispersed into the underlying aqueous within 15 seconds, which may result in a momentary increase of local TA concentration in the aqueous portion and potentially toxic to the retina. Our study suggests that silicone oil may not be a good candidate as a drug reservoir for drugs like TA.

Cost-Effectiveness of Screening for Intermediate Age-Related Macular Degeneration during Diabetic Retinopathy Screening.

PURPOSE: To determine whether screening for age-related macular degeneration (AMD) during a diabetic retinopathy (DR) screening program would be cost effective in Hong Kong. DESIGN: We compared and evaluated the impacts of screening, grading, and vitamin treatment for intermediate AMD compared with no screening using a Markov model. It was based on the natural history of AMD in a cohort with a mean age of 62 years, followed up until 100 years of age or death. PARTICIPANTS: Subjects attending a DR screening program were recruited. METHOD: A cost-effectiveness analysis was undertaken from a public provider perspective. It included grading for AMD using the photographs obtained for DR screening and treatment with vitamin therapy for those with intermediate AMD. The measures of effectiveness were obtained largely from a local study, but the transition probabilities and utility values were from overseas data. Costs were all from local sources. The main assumptions and estimates were tested in sensitivity analyses. MAIN OUTCOME MEASURES: The outcome was cost per quality-adjusted life year (QALY) gained. Both costs and benefits were discounted at 3%. All costs are reported in United States dollars ($). RESULTS: The cost per QALY gained through screening for AMD and vitamin treatment for appropriate cases was $12,712 after discounting. This would be considered highly cost effective based on the World Health Organization's threshold of willingness to pay (WTP) for a QALY, that is, less than the annual per capita gross domestic product of $29,889. Because of uncertainty regarding the utility value for those with advanced AMD, we also tested an extreme, conservative value for utility under which screening remained cost effective. One-way sensitivity analyses revealed that, besides utility values, the cost per QALY was most sensitive to the progression rate from intermediate to advanced AMD. The cost-effectiveness acceptability curve showed a WTP for a QALY of $29,000 or more has a more than 86% probability of being cost effective compared with no screening. CONCLUSIONS: Our analysis demonstrated that AMD screening carried out simultaneously with DR screening for patients with diabetes would be cost effective in a Hong Kong public healthcare setting.

Inhibition of RAP1 enhances corneal recovery following alkali injury.

PURPOSE: Recently, RAP1 (Telomeric Repeat Binding Factor 2, Interacting Protein [TERF2IP]) was discovered as a modulator that selectively regulates nuclear factor light chain kappa enhancer of activated B cells (NFκB) signaling. The roles of RAP1 in regulation of inflammation and angiogenesis for corneal recovery following corneal injury remain poorly understood. The effects of RAP1 deletion on corneal resurfacing and neovascularization in a corneal alkali burn mouse model were examined. METHODS: Corneal defects and neovascularization were induced in vivo by infliction of an alkali burn to the cornea with 1 N sodium hydroxide solution in RAP1 knock-out (RKO) and wild-type (RWT) mice. Corneal resurfacing was evaluated using slit-lamp biomicroscopy. Neovascularization following injury was evaluated by bright view biomicroscopy and immunofluorescence staining with the endothelial marker platelet endothelial cell adhesion molecule (PECAM). The cytokine profiles of corneal tissue involved in inflammation and neovascularization following injury was compared between RKO and RWT mice. Corneal epithelial cells were isolated for classic scratch wound healing assay and further testing with lipopolysaccharide stimulation. RESULTS: Resurfacing of the burned cornea was accelerated and angiogenesis was suppressed, faster recovery of corneal epithelial cells from classic scratch wound healing and superior tolerance of lipopolysaccharides challenge was observed in the RKO compared to RWT. Molecular investigation revealed that deletion of RAP1 reduced upregulation of inflammatory cytokine (IL1A), finely regulated the expression of angiogenic factor (VEGF), and antiangiogenic factor (PEDF), following injury for better corneal recovery. CONCLUSIONS: Deficiency of RAP1 facilitates corneal recovery after injury. Specificity of RAP1 inhibition may lead to design of specific inhibitors of NFκB in the treatment of ocular injuries.

An investigation of the potential association between retinal detachment and oral fluoroquinolones: a self-controlled case series study.

OBJECTIVES: A study reported a significant association between oral fluoroquinolones and the development of retinal detachment among current users of oral fluoroquinolones (Etminan M, Forooghian F, Brophy JM et al. JAMA 2012; 307: 1414-9). However, other published studies have discordant results. This study aimed to investigate this association and to estimate the absolute risk of developing retinal detachment in patients exposed to oral fluoroquinolones. METHODS: A self-controlled case series study was conducted with data retrieved from the Hong Kong Clinical Data Analysis and Reporting System database and the Taiwan National Health Insurance Research Database. Hong Kong and Taiwanese patients who had prescriptions for oral fluoroquinolones and a procedure for retinal detachment between 2001 and 2012 and between 2000 and 2010, respectively, were defined as cases and included in the analysis. RESULTS: A total of 9 events were found during the fluoroquinolone-exposed period and 1407 events were found during the non-exposed period. The adjusted incidence rate ratio in the combined model was 1.26 (0.65-2.47). The crude absolute risk of experiencing retinal detachment whilst on oral fluoroquinolones was ∼1.3 per 200 000 prescriptions. CONCLUSIONS: Our study does not support the association between the use of fluoroquinolones and the development of retinal detachment and our findings are strikingly similar to that of the study conducted in Denmark. Doubt is cast on the association between the use of fluoroquinolones and the development of retinal detachment. Therefore, the use of fluoroquinolones should not be precluded based on the current evidence on the risk of retinal detachment. The impact of different ethnicities on the response to fluoroquinolones should also be investigated.

Novel 'heavy' dyes for retinal membrane staining during macular surgery: multicenter clinical assessment.

PURPOSE: To evaluate the feasibility of two novel 'heavy' dye solutions for staining the internal limiting membrane (ILM) and epiretinal membranes (ERMs), without the need for a prior fluid-air exchange, during macular surgery. METHODS: In this prospective nonrandomized multicenter cohort study, the high molecular weight dyes ILM-Blue™ [0.025% brilliant blue G, 4% polyethylene glycol (PEG)] and MembraneBlue-Dual™ (0.15% trypan blue, 0.025% brilliant blue G, 4% PEG) were randomly used in vitrectomy surgeries for macular disease in 127 eyes of 127 patients. Dye enhanced membrane visualization of the ILM and ERMs, 'ease of membrane peeling', visually detectable perioperative retinal damage, postoperative best-corrected visual acuity (BCVA), dye remnants and other unexpected clinical events were documented by 21 surgeons. RESULTS: All surgeries were uneventful, and a clear bluish staining, facilitating the identification, delineation and removal of the ILM and ERMs, was reported in all but five cases. None of the surgeries required a fluid-air exchange to assist the dye application. BCVA at 1 month after surgery improved in 83% of the eyes in the MembraneBlue-Dual™ group and in 88% in the ILM-Blue™ group. No dye remnants were detected by ophthalmoscopy, and no retinal adverse effects related to the surgery or use of the dyes were observed. CONCLUSION: The 'heavy' dye solutions ILM-Blue™ and MembraneBlue-Dual™ can be injected into a fluid-filled vitreous cavity and may facilitate staining and removal of the ILM and/or ERMs in macular surgery without an additional fluid-air exchange.

Screening for diabetic retinopathy with or without a copayment in a randomized controlled trial: influence of the inverse care law.

OBJECTIVE: To examine whether the inverse care law operates in a screening program for diabetic retinopathy (DR) based on fee for service in Hong Kong. DESIGN: Randomized controlled trial. PARTICIPANTS: All those with type 1 or 2 diabetes from 2 clinics were recruited. INTERVENTION: Diabetic retinopathy screening with a small copayment versus free access in a publicly funded family medicine service. MAIN OUTCOME MEASURES: Uptake of screening and severity of DR detected. Association between these outcome variables and independent variables were determined using multivariate logistic regression models and reported as odds ratios (ORs). RESULTS: After randomization, 1387 subjects in the free group and 1379 subjects in the pay group were eligible for screening, and 94.9% (1316/1387) and 92.6% (1277/1379), respectively, agreed to participate in the study. The offer of screening was accepted by 94.8% (1247/1316) in the free group and 91.2% (1164/1277) in the pay group, and the final uptake ratios were 88.5% (1165/1316) and 82.4% (1052/1277), respectively (Pearson chi = 19.74, P<0.001). Being in the pay group was associated with a lower uptake of screening than being in the free group (OR, 0.59; confidence interval [CI], 0.47-0.74) and a lower detection rate of DR (OR, 0.73; CI, 0.60-0.90) after adjustment for potential confounding factors. Subjects with higher socioeconomic status were more likely to attend screening and had a lower prevalence of DR detected. CONCLUSIONS: The inverse care law seems to operate in a preventive intervention when a relatively small copayment is applied. There is a case for making effective preventive services free of charge. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Human pluripotent stem cell-derived mesenchymal stem cells prevent allergic airway inflammation in mice.

We previously found that mesenchymal stem cells (MSCs) derived from human-induced pluripotent stem cells (iPSCs) exerted immunomodulatory effects on Th2-mediated allergic rhinitis in vitro. However, their contribution to the asthma and allergic rhinitis in animal models remains unclear. In this study, we developed a mouse model of ovalbumin (OVA)-induced allergic inflammation in both the upper and lower airways and evaluated the effects of the systemic administration of human iPSC-MSCs and bone marrow-derived MSCs (BM-MSCs) on allergic inflammation. Our results showed that treatments with both the iPSC-MSCs and BM-MSCs before the challenge phase protected the animals from the majority of allergy-specific pathological changes. This protection included an inhibition of inflammatory cell infiltration and mucus production in the lung, a reduction in eosinophil infiltration in the nose, and a decrease in inflammatory cell infiltration in both the bronchoalveolar and nasal lavage fluids. In addition, treatment with iPSC-MSCs or BM-MSCs before the challenge phase resulted in reduced serum levels of Th2 immunoglobulins (e.g., IgE) and decreased levels of Th2 cytokines including interleukin (IL)-4, IL-5, or IL-13 in the bronchoalveolar and/or nasal lavage fluids. Similar therapeutic effects were observed when the animals were pretreated with human iPSC-MSCs before the sensitization phase. These data suggest that iPSC-MSCs may be used as an alternative strategy to adult MSCs in the treatment of asthma and allergic rhinitis.

Tropism and innate host responses of the 2009 pandemic H1N1 influenza virus in ex vivo and in vitro cultures of human conjunctiva and respiratory tract.

The novel pandemic influenza H1N1 (H1N1pdm) virus of swine origin causes mild disease but occasionally leads to acute respiratory distress syndrome and death. It is important to understand the pathogenesis of this new disease in humans. We compared the virus tropism and host-responses elicited by pandemic H1N1pdm and seasonal H1N1 influenza viruses in ex vivo cultures of human conjunctiva, nasopharynx, bronchus, and lung, as well as in vitro cultures of human nasopharyngeal, bronchial, and alveolar epithelial cells. We found comparable replication and host-responses in seasonal and pandemic H1N1 viruses. However, pandemic H1N1pdm virus differs from seasonal H1N1 influenza virus in its ability to replicate in human conjunctiva, suggesting subtle differences in its receptor-binding profile and highlighting the potential role of the conjunctiva as an additional route of infection with H1N1pdm. A greater viral replication competence in bronchial epithelium at 33 degrees C may also contribute to the slight increase in virulence of the pandemic influenza virus. In contrast with highly pathogenic influenza H5N1 virus, pandemic H1N1pdm does not differ from seasonal influenza virus in its intrinsic capacity for cytokine dysregulation. Collectively, these results suggest that pandemic H1N1pdm virus differs in modest but subtle ways from seasonal H1N1 virus in its intrinsic virulence for humans, which is in accord with the epidemiology of the pandemic to date. These findings are therefore relevant for understanding transmission and therapy.