Peripapillary Pachychoroid Syndrome (PPS): Diagnosing and Treating a Rare Entity.

Two cases with peripapillary pachychoroid syndrome (PPS) along with the challenges concerning correct diagnosis and treatment are presented. In the first case, the patient presented with painless unilateral gradual visual loss. Fundoscopy and optical coherence tomography (OCT) revealed cystoid macular edema (CME) in the left eye (LE), extending from the temporal optic disc margin towards the fovea, with no additional findings. Enhanced-depth imaging- (EDI-) OCT provided additional information and increased choroidal thickness nasally to the macula and pachyvessels in the outer choroidal layer, findings supportive of PPS. Photodynamic therapy (PDT) was applied at the leakage sites. Two months later, CME and subretinal fluid (SRF) had resolved, and VA had significantly improved. In the second case, a patient presented with reduced vision and metamorphopsia bilaterally over the previous 5 days. Fundoscopy revealed CME in both eyes. OCT confirmed the presence of CME in the papillomacular area in the right eye; similarly, CME was recorded in the macula of the LE with SRF located subfoveally. EDI-OCT showed increased choroidal thickness in both eyes. Treatment was administered, originally with dorzolamide eye drops along with eplerenone tablets, and then dexamethasone eye drops that eventually led to significant anatomic and functional improvement. It is important for ophthalmologists to be able to recognize the unique clinical entity of PPS, as its resemblance to disorders with similar features may lead to misdiagnoses and unnecessary, or even incorrect, interventions.

NLRP3 inflammasome in NMDA-induced retinal excitotoxicity.

N-methyl-D-aspartate (NMDA)-induced excitotoxicity is an acute form of experimental retinal injury as a result of overactivation of glutamate receptors. NLRP3 (nucleotide-binding domain, leucine-rich-repeat containing family, pyrin domain containing-3) inflammasome, one of the most studied sensors of innate immunity, has been reported to play a critical role in retinal neurodegeneration with controversial implications regarding neuroprotection and cell death. Thus far, it has not been elucidated whether NMDA-mediated excitotoxicity can trigger NLRP3 inflammasome in vivo. Moreover, it is unknown if NLRP3 is beneficial or detrimental to NMDA-mediated retinal cell death. Here, we employed a murine model of NMDA-induced retinal excitotoxicity by administering 100 nmoles of NMDA intravitreally, which resulted in massive TUNEL+ (TdT-dUTP terminal nick-end labelling) cell death in all retinal layers and especially in retinal ganglion cells (RGCs) 24 h post injection. NMDA insult in the retina potentiates macrophage/microglia cell infiltration, primes the NLRP3 inflammasome in a transcription-dependent manner and induces the expression of interleukin-1ß (IL-1ß). However, despite NLRP3 inflammasome upregulation, systemic deletion of Nlrp3 or Casp1 (caspase-1) did not significantly alter the NMDA-induced, excitotoxicity-mediated TUNEL+ retinal cell death at 24 h (acute phase). Similarly, the deletion of the two aforementioned genes did not alter the survival of the Brn3a+ (brain-specific homeobox/POU domain protein 3A) RGCs in a significant way at 3- or 7-days post injection (long-term phase). Our results indicate that NMDA-mediated retinal excitotoxicity induces immune cell recruitment and NLRP3 inflammasome activity even though inflammasome-mediated neuroinflammation is not a leading contributing factor to cell death in this type of retinal injury.

Clinical characteristics and long-term visual outcome of optic neuritis in neuromyelitis optica spectrum disorder: A comparison between Thai and American-Caucasian cohorts.

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) occurs more commonly in Asian than Caucasian populations. Few studies have examined the clinical features and visual outcome of optic neuritis (ON) within NMOSD in different racial populations. The objective of this study was to compare the clinical characteristics and long-term visual outcome of a Thai and an American-Caucasian cohort with NMOSD-related ON. METHODS: Medical records including brain and orbital magnetic resonance imaging (MRI) of 16 consecutive subjects who developed visual loss due to ON as part of NMOSD evaluated at a single American tertiary referral center between 2006 and 2015 were reviewed and compared to those of 16 consecutive similar subjects evaluated at a single Thai tertiary referral center between 2010 and 2016. These cohorts represented the total number of NMOSD-related ON subjects seen during that time at those institutions. Statistical analyses were used for continuous and categorical data sets, and multiple regression analysis was used to adjust for differences in duration of follow-up and number of episodes of ON in each affected eye. RESULTS: All subjects within the Thai cohort were Asian, while the American cohort initially consisted of 14 Caucasian, 1 Asian and 1 African-American subject, but the latter two were excluded from analysis. In the Thai cohort, ON occurred in 21 eyes, with a total of 19 episodes, while in the American-Caucasian cohort ON occurred in 22 eyes, with a total of 21 episodes. Aquaporin 4 (AQP4)-antibody was positive in all subjects except for one American-Caucasian subject. The mean follow-up time was 17.8 (± 16.0) and 52.8 (± 51.9) months for the Thai and American-Caucasian populations, respectively. There was no difference between the two cohorts with respect to gender, age of NMOSD and NMOSD-related ON onset, initial clinical presentation of NMOSD, initial visual acuity and automated visual fields, prevalence of swollen optic disc in the acute phase, presence of pain on the affected side, mean time of onset of ON symptoms to MRI examination, distribution of segmental involvement of the anterior visual pathway abnormalities based on MRI findings, mean time of onset of ON symptoms to treatment, final visual acuity and automated visual fields. However, a higher proportion of Thai affected eyes were found to have an initial visual acuity of 20/200 or worse compared with the American-Caucasian cohort. Azathioprine was the most common maintenance treatment (75%) used among Thai subjects in contrast to rituximab (78.6%) among American-Caucasian subjects. CONCLUSION: Despite the different prevalence among Thai and American-Caucasian populations, the clinical characteristics of ON in the NMOSD were very similar across these two populations, other than for more severe visual loss initially among Thai subjects. Notably, long-term visual outcome did not differ between these cohorts despite significant difference in the maintenance treatment regimen. This study did not assess neurological status or outcome.

Atorvastatin Promotes Phagocytosis and Attenuates Pro-Inflammatory Response in Human Retinal Pigment Epithelial Cells.

Phagocytosis of daily shed photoreceptor outer segments is an important function of the retinal pigment epithelium (RPE) and it is essential for retinal homeostasis. RPE dysfunction, especially impairment of its phagocytic ability, plays an essential role in the pathogenesis of age-related macular degeneration (AMD). Statins, or HMG CoA (3-hydroxy-3-methylglutaryl-coenzyme A) reductase inhibitors, are drugs with multiple properties that have been extensively used to treat hyperlipidemia. However, their effect on RPE cells has not been fully elucidated. Here we report that high dose atorvastatin increased the phagocytic function of ARPE-19 cells, as well as rescue the cells from the phagocytic dysfunction induced by cholesterol crystals and oxidized low-density lipoproteins (ox-LDL), potentially by increasing the cellular membrane fluidity. Similar effects were observed when evaluating two other hydrophobic statins, lovastatin and simvastatin. Furthermore, atorvastatin was able to block the induction of interleukins IL-6 and IL-8 triggered by pathologic stimuli relevant to AMD, such as cholesterol crystals and ox-LDL. Our study shows that statins, a well-tolerated class of drugs with rare serious adverse effects, help preserve the phagocytic function of the RPE while also exhibiting anti-inflammatory properties. Both characteristics make statins a potential effective medication for the prevention and treatment of AMD.

Demographic, Systemic, and Ocular Factors Associated with Nonarteritic Anterior Ischemic Optic Neuropathy.

OBJECTIVE: Nonarteritic anterior ischemic optic neuropathy (NAION) is a devastating ocular condition causing permanent vision loss. Little is known about risk factors for developing this disease. We assessed demographic, systemic, and ocular factors associated with NAION. DESIGN: Retrospective longitudinal cohort study. PARTICIPANTS: Beneficiaries between 40 and 75 years old without NAION at baseline enrolled in a large U.S. managed care network. METHODS: Enrollees were monitored continuously for ≥2 years between 2001 and 2014 to identify those newly diagnosed with NAION (International Classification of Diseases, 9th Revision, Clinical Modification [ICD-9-CM] code 377.41). All persons were under ophthalmic surveillance and all cases had ≥1 confirmatory ICD-9-CM code for NAION during follow-up. MAIN OUTCOME MEASURES: Multivariable Cox regression modeling was used to generate hazard ratios (HRs) with 95% confidence intervals (CIs) to describe the statistical relationship between selected demographic characteristics, systemic and ocular conditions, and the hazard of developing NAION. RESULTS: Of 1 381 477 eligible enrollees, 977 (0.1%) developed NAION during a mean ± standard deviation (SD) follow-up of 7.8±3.1 years. The mean ± SD age for NAION cases at the index date was 64.0±9.2 years vs. 58.4±9.4 years for the remainder of the beneficiaries. After adjustment for confounding factors, each additional year older was associated with a 2% increased hazard of NAION (HR = 1.02; 95% CI: 1.01-1.03). Female subjects had a 36% decreased hazard of developing NAION (HR = 0.64; 95% CI: 0.55-0.74) compared with male subjects. Compared with whites, Latinos had a 46% decreased hazard of developing NAION (HR = 0.54; 95% CI: 0.36-0.82), whereas African ancestry was not significantly associated with NAION (HR = 0.91; 95% CI: 0.72-1.15). Systemic diseases associated with NAION included hypertension (HR = 1.62; 95% CI: 1.26-2.07) and hypercoagulable states (HR = 2.46; 95% CI: 1.51-4.00). Although diabetes mellitus (DM) was not significantly associated with NAION compared with those without DM (P = 0.45), patients with end-organ involvement from DM had a 27% increased hazard of NAION relative to those with uncomplicated DM (HR = 1.27; 95% CI: 1.01-1.59). Ocular diseases associated with NAION were age-related macular degeneration (HR = 1.29; 95% CI: 1.08-1.54) and retinal vein occlusion (HR = 3.94; 95% CI: 3.11-4.99). CONCLUSIONS: Our study identified several modifiable risk factors that may be associated with NAION. Should future studies confirm these findings, they may offer opportunities to prevent or treat this debilitating condition.

miR-17-3p Exacerbates Oxidative Damage in Human Retinal Pigment Epithelial Cells.

Oxidative stress has been shown to contribute to the development of age-related macular degeneration (AMD). MicroRNAs (miRNA) are small non-coding RNA molecules that function in RNA silencing and post-transcriptional regulation of gene expression. We showed miR-17-3p to be elevated in macular RPE cells from AMD patients and in ARPE-19 cells under oxidative stress. Transfection of miR-17-3p mimic in ARPE-19 induced cell death and exacerbated oxidative lethality that was alleviated by miR-17-3p inhibitor. The expression of antioxidant enzymes manganese superoxide dismutase (MnSOD) and thioredoxin reductase-2 (TrxR2) were suppressed by miR-17-3p mimic and reversed by miR-17-3p inhibitor. These results suggest miR-17-3p aggravates oxidative damage-induced cell death in human RPE cells, while miR-17-3p inhibitor acts as a potential protector against oxidative stress by regulating the expression of antioxidant enzymes.

An Experimental Animal Model of Photodynamic Optic Nerve Head Injury (PONHI).

PURPOSE: Anterior ischemic optic neuropathy (AION) is the most common cause of non-glaucomatous optic nerve head (ONH) injury among older adults. AION results from a sudden ischemic insult to the proximal portion of the optic nerve, typically leading to visual impairment. Here, we present an experimental model of photodynamically induced ONH injury that can be used to study neuroprotective modalities. METHODS: Intraperitoneal injection of mesoporphyrin IX was followed by photodynamic treatment of the ONH in one eye of Brown-Norway rats; the fellow eye received the reverse sequence as a sham control. Fluorescein angiography (FA), spectral domain optical coherence tomography (SD-OCT), and visual evoked potential (VEP) recordings were performed at different time points following laser treatment. Immunohistochemistry was used to monitor apoptotic cell death (TUNEL) and macrophage infiltration (CD68). Cytokine levels were evaluated using enzyme-linked immunosorbent assay (ELISA). RESULTS: FA showed early hyperfluorescence and late leakage of the ONH, while SD-OCT revealed optic nerve edema. No leakage or other abnormalities were detected in control eyes. VEPs were significantly reduced in amplitude and showed prolonged responses compared to sham eyes. The number of apoptotic retinal ganglion cells was elevated one day after laser treatment (13.77 ± 4.49, p < 0.01) and peaked on day 7 (57.22 ± 11.34, p < 0.01). ONH macrophage infiltration also peaked on day 7 (101.8 ± 9.8, p < 0.05). ELISAs performed showed upregulation of macrophage chemoattractant protein-1 and macrophage inflammatory protein-2 on days 3 and 1, respectively. CONCLUSIONS: Photodynamic treatment of the ONH after administration of mesoporphyrin IX leads to macroscopic, histologic, and physiologic evidence of ONH injury. Given the long half-life of mesoporphyrin IX and the ease of intraperitoneal injections, this new model of photodynamically induced ONH injury may be a useful tool for studying optic nerve injury and possible neuroprotective treatments.

Drug Delivery Nanoparticles: Toxicity Comparison in Retinal Pigment Epithelium and Retinal Vascular Endothelial Cells.

Multiple synthetic polymer nanoparticles (NPs) have been widely used as drug delivery systems. However, their toxicity to the retinal pigment epithelium and retinal endothelium remains unclear. In this study, we analyze the cytotoxic effects of three different kinds of NPs, made of poly lactic-co-glycolic acid (PLGA), polycaprolactone (PCL), and PEGylated PLGA (PEG-PLGA), in a retinal pigment epithelium cell line (ARPE-19) and in primary human retinal vascular endothelial cells (RVEC). PEG-PLGA NPs presented the lowest cytotoxicity on ARPE-19 cells and RVEC as assessed by MTT viability assay. While PLGA and PCL exhibited variable amounts of toxicity, no significant toxicity was observed when incubating cells with high PEG-PLGA concentrations (100 µg/ml), for up to 6 days. On both transmission electron microscopy and confocal microscopy, Rhodamine 6G-loaded PEG-PLGA NPs were observed intracellularly in multiple subcellular organelles. PEG-PLGA NPs are a potentially viable option for the treatment of eye diseases.

Mitochondrial DNA has a pro-inflammatory role in AMD.

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in the elderly of industrialized nations, and there is increasing evidence to support a role for chronic inflammation in its pathogenesis. Mitochondrial DNA (mtDNA) has been recently reported to be pro-inflammatory in various diseases such as Alzheimer's and heart failure. Here, we report that intracellular mtDNA induces ARPE-19 cells to secrete inflammatory cytokines IL-6 and IL-8, which have been consistently associated with AMD onset and progression. The induction was dependent on the size of mtDNA, but not on specific sequence. Oxidative stress plays a major role in the development of AMD, and our findings indicate that mtDNA induces IL-6 and IL-8 more potently when oxidized. Cytokine induction was mediated by STING (Stimulator of Interferon Genes) and NF-κB as evidenced by abrogation of the cytokine response with the use of specific inhibitors (siRNA and BAY 11-7082, respectively). Finally, mtDNA primed the NLRP3 inflammasome. This study contributes to our understanding of the potential pro-inflammatory role of mtDNA in the pathogenesis of AMD.

Cholesterol crystals induce inflammatory cytokines expression in a human retinal pigment epithelium cell line by activating the NF-κB pathway.

PURPOSE: To investigate the expression of inflammatory cytokines in ARPE-19 cells after stimulation with cholesterol crystals. METHODS: APRE-19 cells were cultured, primed with IL-1α, and treated with cholesterol crystals under different concentrations. Inflammatory cytokines (mature-IL-1ß, IL-6, and IL-8) in supernatant and inflammatory cytokines (pro-IL-1ß, IL-18) in cell lysate were detected by western blot. The NF-κB pathway inhibitor BAY 11-7082 was used to determine the pathway of cytokine expression. RESULTS: Cholesterol crystals did not induce the nucleotide-binding domain leucine-rich repeat containing family, pyrin domain containing 3 (NLRP3) inflammasome, but did increase pro-IL-1ß expression in ARPE-19 cells. Cholesterol crystals increased pro-IL-1ß expression by activating the NF-κB pathway. Cholesterol crystal activation of the NF-κB pathway also leads to increased IL-6 and IL-8 expression. CONCLUSION: Cholesterol crystals can induce inflammatory cytokine expression in ARPE-19 cells by activating the NF-κB pathway.

TP53 Arg72Pro polymorphism and colorectal cancer risk: a systematic review and meta-analysis.

BACKGROUND: The TP53 rs1042522 polymorphism (c.215C>G, Arg72Pro) has been extensively investigated as a potential risk factor for colorectal cancer, but the results have thus far been inconclusive. METHODS: We searched multiple electronic databases to identify studies investigating the association between the Arg72Pro polymorphism and colorectal cancer. Individual study odds ratios (OR) and their confidence intervals were estimated using allele-frequency, recessive, and dominant genetic models. Summary ORs where estimated using random effects models. RESULTS: We identified 23 eligible case-control studies, investigating 6,514 cases and 9,334 controls. There was significant between-study heterogeneity for all genetic models. The control group in one of the studies was not in Hardy-Weinberg equilibrium; only three studies reported that genotyping was blinded to case/control status and five studies used tumor tissue for case genotyping. Overall, we did not identify any association between rs1042522 and colorectal cancer risk under an allele-frequency comparison (OR, 0.99; 95% confidence interval, 0.89-1.09). Likewise, no association was evident under dominant or recessive models. Studies using tumor tissue for case genotyping found a protective effect for the Pro allele, compared with studies using somatic DNA (P(interaction) = 0.03). Results were also inconsistent between different genotyping methods (P(interaction) = 0.03). CONCLUSION: We did not identify an association between TP53 rs1042522 and colorectal cancer. Published results seem to be driven by technical artifacts rather than true biological effects. IMPACT: Future genetic association studies should use more rigorous genotyping methods and avoid the use of tumor tissue as a source of DNA to prevent genotype misclassification due to loss of heterozygosity.