Identification of vitreous proteins in retinopathy of prematurity

SERPINA3 in Diabetic Retinopathy: A Pilot Study Assessing the Impact of Prior COVID-19 Infection on Patients

PURPOSE

SERine Protease INhibitor clade A member 3 (SERPINA3), a protease inhibitor involved in the acute phase response, is regulated by interleukin 6 trans-signaling, a pro-inflammatory pathway associated with diabetic retinopathy (DR) pathogenesis. We hypothesized that SERPINA3 may serve as a biomarker to distinguish DR patients from diabetic patients without retinopathy.

METHODS

We measured serum SERPINA3 levels in DR patients and demographically matched diabetic patients without retinopathy to assess the biomarker potential of SERPINA3. History of COVID-19 infection was included as a demographic variable.

RESULTS

Our results showed that SERPINA3 levels did not vary between cases and controls, nor was there any correlation with disease severity as measured by hemoglobin A1c and diabetic retinopathy stage. We found that excluding patients with a history of COVID-19 infection increased the predictive value of SERPINA3, and that SERPINA3 levels were significantly increased in those subjects hospitalized due to COVID-19. The predictive value of SERPINA3 for hospitalization was similar to age, duration of diabetes, and HbA1c in our cohort.

CONCLUSIONS

Overall, SERPINA3 had poor sensitivity and specificity for identifying DR patients, and COVID-19 infection history significantly increased variance in SERPINA3 levels. Further investigation into the potential of SERPINA3 as DR biomarker should be sufficiently powered to account for the potentially confounding effects of COVID-19 infection.

Retinopathy of Prematurity (ROP): An Overview of Biomarkers in Various Samples for Prediction, Diagnosis, and Prognosis

Retinopathy of Prematurity (ROP) is a proliferative retinal vascular disease marked by abnormal development of retinal vessels in low birth weight preterm infants. It is one of the leading causes of blindness in preterm infants. Current ROP screening methods impose high demands on both the equipment and the expertise of ophthalmologists, which limits their widespread application, particularly in secondary hospitals and remote areas. Thus, the identification of relevant biomarkers and the development of simpler detection methods are important and promising. Non-invasive or minimally invasive sampling methods, along with biomarkers possessing high sensitivity and specificity, could greatly enhance neonatal screening, facilitate early diagnosis, and improve prevention of blindness in preterm infants. This review provides relevant medical insights for clinical practice. This review explored, compares and analyzes various sampling sources. It compares and analyzes research on ROP-related biomarkers derived from these samples.

Punctate hyperreflective vitreous opacities: a ubiquitous finding in healthy children beyond infancy

BACKGROUND

The vitreous evolves from birth over lifetime. Little is known about the appearance of the healthy vitreous during childhood. We aimed to characterise posterior vitreous features in healthy children using spectral domain optical coherence tomography (SD-OCT).

METHODS

Retrospective cohort study including healthy eyes of 78 children aged 2-12 years and 39 healthy adults. Patients diagnosed with intraocular inflammation or vitreoretinal pathology were excluded.

MAIN OUTCOME

Proportion of eyes with presence of punctate hyperreflective vitreous opacities (PHVO). Percentage of B-scans demonstrating PHVO within an OCT volume scan, correlation between presence of PHVO and patients' age group, retinal measurements, and presence of premacular bursa were analysed.

RESULTS

154 paediatric eyes (median age 9.08 (IQR 5.17-9.75) years) and 76 adult eyes (30.75 (IQR 26.42-38.08) years) were included; 12244 OCT images were reviewed. All eyes (100%) in the paediatric group and 73% in the adult group presented PHVO. The median percentage of OCT images showing PHVO was 77.05% (IQR 51.23-88.52) in children and 8.0% (IQR 0-16.03) in adults (p < 0.001). Separate analysis of right and left eyes confirmed the results (p < 0001). Premacular bursa appeared in 20.5% of paediatric and 31.6% of adult eyes (p = 0.103). Mean central subfield thickness was significantly lower in children (257 ± 21 µm vs. 276 ± 18 µm, p < 0.001), while median total macular volume was similar (8.59 (IQR 8.25-8.86) mm3 vs. 8.62 (IQR 8.39-8.96) mm3, p = 0.145).

CONCLUSIONS

This study demonstrates that PHVO are ubiquitous physiologic vitreous findings in healthy children beyond infancy. These findings enhance the understanding of the development of the posterior segment of the eye and might improve paediatric OCT interpretation, potentially avoiding misdiagnoses and unnecessary interventions in children.

The macular microvascular changes in children with a history of retinopathy of prematurity treated with intravitreal Bevacizumab injection using optical coherence tomography angiography: a retrospective cohort

OBJECTIVE

Our study aims to evaluate and compare the macular microvascular condition of the intravitreal Bevacizumab (IVB)-treated retinopathy of prematurity (ROP) cases to the preterm cases without ROP and spontaneously regressed ROPs.

METHODS

It is a retrospective cohort of 50 premature neonates visited from 2016 to 2017 for ROP screening in Nikookari Eye Hospital and recalled for re-evaluation in 2022. These patients were classified into three groups based on their medical documents: 1. Preterm cases without ROP (PT), 2. Spontaneously regressed ROPs (SR), and 3. IVB-treated ROPs (IVB). All the included cases underwent a thorough ophthalmic exam, cyclo-refraction, Best-corrected visual acuity (BCVA) assessment, and macular optical coherence tomography angiography (OCTA). The foveal thickness, foveal avascular zone (FAZ) area, foveal, parafoveal, and perifoveal vascular density (VD) were evaluated as the quantitative variables.

RESULTS

Twenty-five male and 25 female cases with a median age of 5.0 entered the study. Twenty-six eyes were evaluated in the PT group, 50 in the SR group, and 24 in the IVB group. The SR group consisted of 25 zone-2 and 25 zone-3 ROPs. In comparison, the IVB group consisted of 9 zone-1 and 15 zone-2 ROPs (p: < 001). Also, zone-2 cases were more advanced in the IVB group. The IVB-treated eyes demonstrated a significantly higher foveal superficial capillary plexus (SCP) VD than the others (28.5% vs. 23.1 and 22.9, respectively, in PT and SR, p:0.008). However, the parafoveal deep capillary plexus (DCP) VD was lower than the PT cases (48.5% vs. 53.4, p:0.034). The FAZ area was also smaller than the PT cases (0.113 vs.0.219 mm2, p:0.032). The FAZ area was significantly positively correlated with the foveal SCP and DCP VD and negatively correlated with parafoveal DCP VD (CC: -0.770, -0.719, 0.377, respectively, p: < 0.001).

CONCLUSION

In the long term, although the IVB-treated ROP cases experience an excellent visual outcome comparable to those without ROP, they may show some macular microvascular changes. These changes might be related to the effect of IVB or the nature of more advanced stages of ROP.

Prostanoid signaling in retinal vascular diseases

The vasculature of the retina is exposed to systemic and local factors that have the capacity to induce several retinal vascular diseases, each of which may lead to vision loss. Prostaglandin signaling has arisen as a potential therapeutic target for several of these diseases due to the diverse manners in which these lipid mediators may affect retinal blood vessel function. Previous reports and clinical practices have investigated cyclooxygenase (COX) inhibition by nonsteroidal anti-inflammatory drugs (NSAIDs) to address retinal diseases with varying degrees of success; however, targeting individual prostanoids or their distinct receptors affords more signaling specificity and poses strong potential for therapeutic development. This review offers a comprehensive view of prostanoid signaling involved in five key retinal vascular diseases: retinopathy of prematurity, diabetic retinopathy, age-related macular degeneration, retinal occlusive diseases, and uveitis. Mechanistic and clinical studies of these lipid mediators provide an outlook for therapeutic development with the potential to reduce vision loss in each of these conditions.

4D label-free proteomics analysis of oxygen-induced retinopathy with or without anti-VEGF treatment

Oxygen-induced retinopathy (OIR) animal model is widely used for retinopathy of prematurity (ROP) researches. The purpose of this study was to identify proteins and related pathways of OIR with or without anti-vascular endothelial growth factor (VEGF) treatment, for use as biomarkers in diagnosing and treating ROP. Nine samples were subjected to proteomic analysis. Retina specimens were collected from 3 OIR mice, 3 OIR mice with anti-VEGF treatment and 3 normal mice (control group). Liquid chromatography-tandem mass spectrometry analysis was performed using the 4D label-free technique. Statistically significant differentially expressed proteins, gene ontology (GO) terms, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway representations, InterPro (IPR) and protein interactions were analyzed. In total, 4585 unique proteins were identified as differentially expressed proteins (DEPs). Enrichment analysis of the GO and KEGG indicated functional clusters related to peptide biosynthetic and metabolic process, cellular macromolecule biosynthetic process and nucleic acid binding in OIR group. For anti-VEGF treatment group, DEPs were clustered in DNA replication, PI3K/Akt signaling pathway and Jak/STAT signaling pathway. Proteomic profiling is useful for the exploration of molecular mechanisms of OIR and mechanisms of anti-VEGF treatment. These findings may be useful for identification of novel biomarkers for ROP pathogenesis and treatment.

Role of Serine Protease Inhibitors A1 and A3 in Ocular Pathologies

Serine protease inhibitors A1 (SerpinA1) and A3 (SerpinA3) are important members of the serpin family, playing crucial roles in the regulation of serine proteases and influencing various physiological processes. SerpinA1, also known as α-1-antitrypsin, is a versatile glycoprotein predominantly synthesized in the liver, with additional production in inflammatory and epithelial cell types. It exhibits multifaceted functions, including immune modulation, complement activation regulation, and inhibition of endothelial cell apoptosis. SerpinA3, also known as α-1-antichymotrypsin, is expressed both extracellularly and intracellularly in various tissues, particularly in the retina, kidney, liver, and pancreas. It exerts anti-inflammatory, anti-angiogenic, antioxidant, and antifibrotic activities. Both SerpinA1 and SerpinA3 have been implicated in conditions such as keratitis, diabetic retinopathy, age-related macular degeneration, glaucoma, cataracts, dry eye disease, keratoconus, uveitis, and pterygium. Their role in influencing metalloproteinases and cytokines, as well as endothelial permeability, and their protective effects on Müller cells against oxidative stress further highlight their diverse and critical roles in ocular pathologies. This review provides a comprehensive overview of the etiology and functions of SerpinA1 and SerpinA3 in ocular diseases, emphasizing their multifaceted roles and the complexity of their interactions within the ocular microenvironment.

Biomarkers of Pediatric Cataracts: A Proteomics Analysis of Aqueous Fluid

Cataracts are among the most common causes of childhood vision loss worldwide. This study seeks to identify differentially expressed proteins in the aqueous humor of pediatric cataract patients. Samples of aqueous humor were collected from pediatric and adult cataract patients and subjected to mass spectrometry-based proteomic analysis. Samples of pediatric cataracts were grouped by subtype and compared to adult samples. Differentially expressed proteins in each subtype were identified. Gene ontology analysis was performed using WikiPaths for each cataract subtype. Seven pediatric patients and ten adult patients were included in the study. Of the pediatric samples, all seven (100%) were male, three (43%) had traumatic cataracts, two (29%) had congenital cataracts, and two (29%) had posterior polar cataracts. Of the adult patients, seven (70%) were female and seven (70%) had predominantly nuclear sclerotic cataracts. A total of 128 proteins were upregulated in the pediatric samples, and 127 proteins were upregulated in the adult samples, with 75 proteins shared by both groups. Gene ontology analysis identified inflammatory and oxidative stress pathways as upregulated in pediatric cataracts. Inflammatory and oxidative stress mechanisms may be involved in pediatric cataract formation and warrant further investigation.

Vitreous opacities in infants born full-term and preterm by handheld swept-source optical coherence tomography

PURPOSE

To compare vitreous opacity density in infants born at term and in infants born prematurely using an investigational handheld swept-source optical coherence tomography (SS-OCT).

METHODS

Infants born at term underwent imaging once between 12 and 48 hours after birth; infants born prematurely were imaged at each routine retinopathy of prematurity (ROP) examination. Three masked, trained graders analyzed images. Semiautomated methods were used to quantify vitreous opacity density, which was correlated with ROP severity based on indirect ophthalmoscopy, other SS-OCT findings, and medical comorbidities.

RESULTS

Between April 2018 and June 2019, 251 SS-OCT imaging sessions were performed on 78 infants (49% female; 36% preterm, with mean birth weight of 1018 ± 338 g and gestational age of 28.6 ± 3.2 weeks). All SS-OCT sessions produced images of adequate quality. Punctate vitreous opacities were present in 25 of 28 term infants (89%) and 41 of 50 premature infants (82%). Dice coefficient and F1 scores for intergrader agreement were 0.99 ± 0.03 and 0.77 ± 0.31, respectively. Vitreous opacity density was 0.118 ± 0.187 in prematurely born infants and 0.031 ± 0.118 in infants born at term (P = 0.009). In the former, vitreous opacity density was associated with ROP zone (P = 0.044) and stage (P = 0.031), intraventricular hemorrhage (P = 0.028), subchorionic hemorrhage (P = 0.026), and African American race (P = 0.023). In the latter, vitreous opacity density was associated with maternal diabetes (P = 0.049).

CONCLUSIONS

Our investigational handheld SS-OCT achieved high-quality vitreoretinal images. In our study cohort, punctate vitreous opacities were a frequent finding in infants born at term and those born prematurely, with increased density in those born prematurely, particularly those with severe ROP.

Identification of Interphotoreceptor retinoid-binding protein in the Schisis cavity fluid of a patient with congenital X-linked Retinoschisis

Background

This case report describes the surgical outcome in a patient with congenital X-linked retinoschisis (CXLRS) and the results of proteomic analysis of surgically extracted samples from both vitreous and intraschisis cavities by mass spectrometry.

Case presentation

A 3-month-old boy presented with extensive retinoschisis involving macula and retinal periphery in both eyes. Genetic analysis confirmed retinoschisin 1 mutation (c.554C > T), and an electroretinogram showed significant reduction of b-wave and decreased cone and rod responses, which led to a diagnosis of CXLRS. By performing pars plana vitrectomy, including inner wall retinectomy, clear visual axes with stable retinal conditions and functional vision in both eyes were obtained during the 4 years of follow-up. Proteomic analysis of surgically retrieved fluid from the intraschisis cavity revealed a higher expression of interphotoreceptor retinoid-binding protein (IRBP) than that from the vitreous humor. However, both samples showed equal levels of albumin, transferrin, and pigment epithelium-derived factor.

Conclusions

Cellular adhesive imperfection in CXLRS may cause IRBP diffusion from the interphotoreceptor matrix, resulting in the strong expression of IRBP in the intraschisis cavity. An impaired retinoid cycle caused by an absence of IRBP in the retina may potentially underlie the pathology of CXLRS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-02234-5.

Proteomic Analyses of Vitreous in Proliferative Diabetic Retinopathy: Prior Studies and Future Outlook

Vitreous fluid is becoming an increasingly popular medium for the study of retinal disease. Numerous studies have demonstrated that proteomic analysis of the vitreous from patients with proliferative diabetic retinopathy yields valuable molecular information regarding known and novel proteins and pathways involved in this disease. However, there is no standardized methodology for vitreous proteomic studies. Here, we share a suggested protocol for such studies and outline the various experimental and analytic methods that are currently available. We also review prior mass spectrometry-based proteomic studies of the vitreous from patients with proliferative diabetic retinopathy, discuss common pitfalls of these studies, and propose next steps for moving the field forward.

Tear Fluid Angiogenic Factors: Potential Noninvasive Biomarkers for Retinopathy of Prematurity Screening in Preterm Infants

Purpose

To determine the status of proangiogenic factors in the tear fluid of preterm infants with and without retinopathy of prematurity (ROP).

Methods

Preterm infants (n = 36) undergoing routine ROP screening included in the prospective study were categorized as No-ROP (n = 13, no ROP at any visits), ROP (if ROP was present at first visit; n = 18), or No-ROP to ROP (no disease at first visit, but developed ROP subsequently; n = 5). Infants with ROP were also grouped as progressing (n = 7) and regressing (n = 16) based on ROP evolution between the first and subsequent visits. Schirmer's strips were used to collect tear fluid and proangiogenic factors (VEGF, angiogenin, soluble vascular cell adhesion molecule, and fractalkine) levels (in picograms per milliliter) in tear fluid were measured by multiplex ELISA.

Results

Lower levels of VEGF (135 ± 69; mean ± standard deviation) and higher levels of angiogenin (6568 ± 4975) were observed in infants with ROP compared with infants without ROP (172.5 ± 54.0; 4139 ± 3909) at the first visit. Significantly lower levels of VEGF were observed in the No-ROP to ROP group compared with the No-ROP and ROP groups. The VEGF and angiogenin levels at the first visit were significantly lower in infants with ROP with progressing disease. Angiogenin levels negatively correlated with birth weight and gestational age in ROP. The area under the curve (AUC) and odds ratio (OR) analysis demonstrated that angiogenin/birth weight (AUC = 0.776; OR, 8.6); angiogenin/gestational age (AUC = 0.706; OR, 7.3) and Angiogenin/VEGF (AUC = 0.806; OR, 14.3) ratios were able to differentiated preterm infants with and without ROP.

Conclusions

The association between angiogenin and ROP suggests its possible role in ROP. The ratio of angiogenin level with birth weight, gestational age, and/or VEGF could serve as a potential noninvasive screening biomarker for ROP.

Translational Research in Retinopathy of Prematurity: From Bedside to Bench and Back Again

Retinopathy of prematurity (ROP), a vascular proliferative disease affecting preterm infants, is a leading cause of childhood blindness. Various studies have investigated the pathogenesis of ROP. Clinical experience indicates that oxygen levels are strongly correlated with ROP development, which led to the development of oxygen-induced retinopathy (OIR) as an animal model of ROP. OIR has been used extensively to investigate the molecular mechanisms underlying ROP and to evaluate the efficacy of new drug candidates. Large clinical trials have demonstrated the efficacy of anti-vascular endothelial growth factor (VEGF) agents to treat ROP, and anti-VEGF therapy is presently becoming the first-line treatment worldwide. Anti-VEGF therapy has advantages over conventional treatments, including being minimally invasive with a low risk of refractive error. However, long-term safety concerns and the risk of late recurrence limit this treatment. There is an unmet medical need for novel ROP therapies, which need to be addressed by safe and minimally invasive therapies. The recent progress in biotechnology has contributed greatly to translational research. In this review, we outline how basic ROP research has evolved with clinical experience and the subsequent emergence of new drugs. We discuss previous and ongoing trials and present the candidate molecules expected to become novel targets.

Exploration of Oxygen-Induced Retinopathy Model to Discover New Therapeutic Drug Targets in Retinopathies

Oxygen-induced retinopathy (OIR) is a pure hypoxia-driven angiogenesis model and the most widely used model for ischemic retinopathies, such as retinopathy of prematurity (ROP), proliferative diabetic retinopathy (PDR), and retinal vein occlusion (RVO). OIR model has been used to test new potential anti-angiogenic factors for human diseases. We have recently performed the most comprehensive characterization of OIR by a relatively novel mass spectrometry (MS) technique, sequential window acquisition of all theoretical fragment ion mass spectra (SWATH-MS) proteomics and used genetically modified mice strains to identify novel molecular drug targets in angiogenic retinal diseases. We have confirmed the relevance of the identified molecular targets to human diseases by determining their expression pattern in neovascular membranes obtained from PDR and RVO patients. Based on our results, crystallins were the most prominent proteins induced by early hypoxic environment during the OIR, while actomyosin complex and Filamin A-R-Ras axis, that regulates vascular permeability of the angiogenic blood vessels, stood out at the peak of angiogenesis. Our results have revealed potential new therapeutic targets to address hypoxia-induced pathological angiogenesis and the associated vascular permeability in number of retinal diseases.

Inhibition of retinal neovascularization by a PEDF-derived nonapeptide in newborn mice subjected to oxygen-induced ischemic retinopathy

Retinopathy of prematurity (ROP) is a growing cause of lifelong blindness and visual defects as improved neonatal care worldwide increases survival in very-low-birthweight preterm newborns. Advancing ROP is managed by laser surgery or a single intravitreal injection of anti-VEGF, typically at 33-36 weeks gestational age. While newer methods of scanning and telemedicine improve monitoring ROP, the above interventions are more difficult to deliver in developing countries. There is also concern as to laser-induced detachment and adverse developmental effects in newborns of anti-VEGF treatment, spurring a search for alternative means of mitigating ROP. Pigment epithelium-derived factor (PEDF), a potent angiogenesis inhibitor appears late in gestation, is undetected in 25-28 week vitreous, but present at full term. Its absence may contribute to ROP upon transition from high-to-ambient oxygen environment or with intermittent hypoxia. We recently described antiangiogenic PEDF-derived small peptides which inhibit choroidal neovascularization, and suggested that their target may be laminin receptor, 67LR. The latter has been implicated in oxygen-induced ischemic retinopathy (OIR). Here we examined the effect of a nonapeptide, PEDF 336, in a newborn mouse OIR model. Neovascularization was significantly decreased in a dose-responsive manner by single intravitreal (IVT) injections of 1.25-7.5 μg/eye (1.0-6.0 nmol/eye). By contrast, anti-mouse VEGFA₁₆₄ was only effective at 25 ng/eye, with limited dose-response. Combination of anti-VEGFA₁₆₄ with PEDF 336 gave only the poorer anti-VEGF response while abrogating the robust inhibition seen with peptide-alone, suggesting a need for VEGF in sensitizing the endothelium to the peptide. VEGF stimulated 67LR presentation on endothelial cells, which was decreased in the presence of PEDF 336. Mouse and rabbit eyes showed no histopathology or inflammation after IVT peptide injection. Thus, PEDF 336 is a potential ROP therapeutic, but is not expected to be beneficial in combination with anti-VEGF.

Vitreous humor endogenous compounds analysis for post-mortem forensic investigation

The chemical and biochemical analysis of bodily fluids after death is an important thanatochemical approach to assess the cause and time since death. Vitreous humor (VH) has been used as a biofluid for forensic purposes since the 1960s. Due to its established relevance in toxicology, a literature review highlighting the use of VH with an emphasis on endogenous compounds has not yet been undertaken. VH is a chemically complex aqueous solution of carbohydrates, proteins, electrolytes and other small molecules present in living organisms; this biofluid is useful tool for its isolated environment, preserved from bacterial contamination, decomposition, autolysis, and metabolic reactions. The post-mortem analysis of VH provides an important tool for the estimation of the post-mortem interval (PMI), which can be helpful in determining the cause of death. Consequently, the present review evaluates the recent chemical and biochemical advances with particular importance on the endogenous compounds present at the time of death and their modification over time, which are valuable for the PMI prediction and to identify the cause of death.

Novel anti-angiogenic PEDF-derived small peptides mitigate choroidal neovascularization

Abnormal migration and proliferation of endothelial cells (EC) drive neovascular retinopathies. While anti-VEGF treatment slows progression, pathology is often supported by decrease in intraocular pigment epithelium-derived factor (PEDF), an endogenous inhibitor of angiogenesis. A surface helical 34-mer peptide of PEDF, comprising this activity, is efficacious in animal models of neovascular retina disease but remains impractically large for therapeutic use. We sought smaller fragments within this sequence that mitigate choroidal neovascularization (CNV). Expecting rapid intravitreal (IVT) clearance, we also developed a method to reversibly attach peptides to nano-carriers for extended delivery. Synthetic fragments of 34-mer yielded smaller anti-angiogenic peptides, and N-terminal capping with dicarboxylic acids did not diminish activity. Charge restoration via substitution of an internal aspartate by asparagine improved potency, achieving low nM apoptotic response in VEGF-activated EC. Two optimized peptides (PEDF 335, 8-mer and PEDF 336, 9-mer) were tested in a mouse model of laser-induced CNV. IVT injection of either peptide, 2-5 days before laser treatment, gave significant CNV decrease at day +14 post laser treatment. The 8-mer also decreased CNV, when administered as eye drops. Also examined was a nanoparticle-conjugate (NPC) prodrug of the 9-mer, having positive zeta potential, expected to display longer intraocular residence. This NPC showed extended efficacy, even when injected 14 days before laser treatment. Neither inflammatory cells nor other histopathologic abnormalities were seen in rabbit eyes harvested 14 days following IVT injection of PEDF 336 (>200 μg). No rabbit or mouse eye irritation was observed over 12-17 days of PEDF 335 eye drops (10 mM). Viability was unaffected in 3 retinal and 2 choroidal cell types by PEDF 335 up to 100 μM, PEDF 336 (100 μM) gave slight growth inhibition only in choroidal EC. A small anti-angiogenic PEDF epitope (G-Y-D-L-Y-R-V) was identified, variants (adipic-Sar-Y-N-L-Y-R-V) mitigate CNV, with clinical potential in treating neovascular retinopathy. Their shared active motif, Y - - - R, is found in laminin (Ln) peptide YIGSR, which binds Ln receptor 67LR, a known high-affinity ligand of PEDF 34-mer.

The alternative splicing of SKU5-Similar3 in Arabidopsis

Alternative splicing largely enhanced the diversity of transcriptome and proteome in eukaryas. Along with technological development, more and more genes are reported to be alternatively spliced during mRNA maturation. Here, I report the alternative splicing of SKU5-Similar 3 (SKS3) and its special splicing site in Arabidopsis. SKS3 was predicted to be alternatively transcribed into two variants, SKS3.1 and SKS3.2, which encoded a GPI-anchored protein and a soluble secretory protein, respectively. But, according to experimental data, instead of SKS3.2, a novel variant, SKS3.3, which encodes a protein with a transmembrane region at its C-terminus, was demonstrated. Interestingly, it exhibites a different organ-specific expression pattern with SKS3.1, and an unusual intron splicing site not following 'GT-AG' rule or any reported rule.

A chronic hypoxic response in photoreceptors alters the vitreous proteome in mice

Reduced oxygenation of the outer retina in the aging eye may activate a chronic hypoxic response in RPE and photoreceptor cells and is considered as a risk factor for the development of age-related macular degeneration (AMD). In mice, a chronically active hypoxic response in the retinal pigment epithelium (RPE) or photoreceptors leads to age-dependent retinal degeneration. To identify proteins that may serve as accessible markers for a chronic hypoxic insult to photoreceptors, we used proteomics to determine the protein composition of the vitreous humor in genetically engineered mice that lack the von Hippel-Lindau tumor suppressor (Vhl) specifically in rods (rod^ΔVhl) or cones (all-cone^ΔVhl). Absence of VHL leads to constitutively active hypoxia-inducible transcription factors (HIFs) and thus to a molecular response to hypoxia even in normal room air. To discriminate between the consequences of a local response in photoreceptors and systemic hypoxic effects, we also evaluated the vitreous proteome of wild type mice after exposure to acute hypoxia. 1'043 of the identified proteins were common to all three hypoxia models. 257, 258 and 356 proteins were significantly regulated after systemic hypoxia, in rod^ΔVhl and in all-cone^ΔVhl mice, respectively, at least at one of the analyzed time points. Only few of the regulated proteins were shared by the models indicating that the vitreous proteome is differentially affected by systemic hypoxia and the rod or cone-specific hypoxic response. Similarly, the distinct protein compositions in the individual genetic models at early and late time points suggest regulated, cell-specific and time-dependent processes. Among the proteins commonly regulated in the genetic models, guanylate binding protein 2 (GBP2) showed elevated levels in the vitreous that were accompanied by increased mRNA expression in the retina of both rod^ΔVhl and all-cone^ΔVhl mice. We hypothesize that some of the differentially regulated proteins at early time points may potentially be used as markers for the detection of a chronic hypoxic response of photoreceptors.

An iTRAQ-Based Quantitative Proteomic Analysis of Plasma Proteins in Preterm Newborns With Retinopathy of Prematurity

Purpose

Retinopathy of prematurity (ROP) is a vision-threatening complication of a premature birth, in which the etiology still remains unclear. Importantly, the molecular processes that govern these effects can be investigated in a perturbed plasma proteome composition. Thus, plasma proteomics may add new insights into a better understanding of the pathogenesis of this disease.

Methods

The cord and peripheral blood of neonates (≤30 weeks gestational age) was drawn at birth and at the 36th postmenstrual week (PMA), respectively. Blood samples were retrospectively subdivided into ROP(+) and ROP(-) groups, according to the development of ROP.

Results

The quantitative analysis of plasma proteome at both time points revealed 30 protein abundance changes between ROP(+) and ROP(-) groups. After standardization to gestational age, children who developed ROP were characterized by an increased C3 complement component and fibrinogen level at both analyzed time points.

Conclusions

Higher levels of the complement C3 component and fibrinogen, present in the cord blood and persistent to 36 PMA, may indicate a chronic low-grade systemic inflammation and hypercoagulable state that may play a role in the development of ROP.

Personalized Proteomics for Precision Health: Identifying Biomarkers of Vitreoretinal Disease

Proteomic analysis is an attractive and powerful tool for characterizing the molecular profiles of diseased tissues, such as the vitreous. The complexity of data available for analysis ranges from single (e.g., enzyme-linked immunosorbent assay [ELISA]) to thousands (e.g., mass spectrometry) of proteins, and unlike genomic analysis, which is limited to denoting risk, proteomic methods take snapshots of a diseased vitreous to evaluate ongoing molecular processes in real time. The proteome of diseased ocular tissues was recently characterized, uncovering numerous biomarkers for vitreoretinal diseases and identifying protein targets for approved drugs, allowing for drug repositioning. These biomarkers merit more attention regarding their therapeutic potential and prospective validation, as well as their value as reproducible, sensitive, and specific diagnostic markers.

TRANSLATIONAL RELEVANCE

Personalized proteomics offers many advantages over alternative precision-health platforms for the diagnosis and treatment of vitreoretinal diseases, including identification of molecular constituents in the diseased tissue that can be targeted by available drugs.