Role of Lnc-RNAs in the Pathogenesis and Development of Diabetic Retinopathy

Important advances in diabetic retinopathy (DR) research and management have occurred in the last few years. Neurodegenerative changes before the onset of microvascular alterations have been well established. So, new strategies are required for earlier and more effective treatment of DR, which still is the first cause of blindness in working age. We describe herein gene regulation through Lnc-RNAs as an interesting subject related to DR. Long non-coding RNAs (Lnc-RNAs) are non-protein-coding transcripts larger than 200 nucleotides. Lnc-RNAs regulate gene expression and protein formation at the epigenetic, transcriptional, and translational levels and can impact cell proliferation, apoptosis, immune response, and oxidative stress. These changes are known to take part in the mechanism of DR. Recent investigations pointed out that Lnc-RNAs might play a role in retinopathy development as Metastasis-Associated Lung Adenocarcinoma Transcript (Lnc-MALAT1), Maternally expressed gene 3 (Lnc-MEG3), myocardial-infarction-associated transcript (Lnc-MIAT), Lnc-RNA H19, Lnc-RNA HOTAIR, Lnc-RNA ANRIL B-Raf proto-oncogene (Lnc-RNA BANCR), small nucleolar RNA host gene 16 (Lnc-RNA SNHG16) and others. Several molecular pathways are impacted. Some of them play a role in DR pathophysiology, including the PI3K-Akt signaling axis, NAD-dependent deacetylase sirtuin-1 (Sirti1), p38 mitogen-activated protein kinase (P38/mapk), transforming growth factor beta signaling (TGF-β) and nuclear factor erythroid 2-related factor 2 (Nrf2). The way Lnc-RNAs affect diabetic retinopathy is a question of great relevance. Performing a more in-depth analysis seems to be crucial for researchers if they want to target Lnc-RNAs. New knowledge on gene regulation and biomarkers will enable investigators to develop more specialized therapies for diabetic retinopathy, particularly in the current growing context of precision medicine.

Association between convalescent plasma treatment and mortality in COVID-19: a collaborative systematic review and meta-analysis of randomized clinical trials

BACKGROUND

Convalescent plasma has been widely used to treat COVID-19 and is under investigation in numerous randomized clinical trials, but results are publicly available only for a small number of trials. The objective of this study was to assess the benefits of convalescent plasma treatment compared to placebo or no treatment and all-cause mortality in patients with COVID-19, using data from all available randomized clinical trials, including unpublished and ongoing trials (Open Science Framework, https://doi.org/10.17605/OSF.IO/GEHFX ).

METHODS

In this collaborative systematic review and meta-analysis, clinical trial registries (ClinicalTrials.gov, WHO International Clinical Trials Registry Platform), the Cochrane COVID-19 register, the LOVE database, and PubMed were searched until April 8, 2021. Investigators of trials registered by March 1, 2021, without published results were contacted via email. Eligible were ongoing, discontinued and completed randomized clinical trials that compared convalescent plasma with placebo or no treatment in COVID-19 patients, regardless of setting or treatment schedule. Aggregated mortality data were extracted from publications or provided by investigators of unpublished trials and combined using the Hartung-Knapp-Sidik-Jonkman random effects model. We investigated the contribution of unpublished trials to the overall evidence.

RESULTS

A total of 16,477 patients were included in 33 trials (20 unpublished with 3190 patients, 13 published with 13,287 patients). 32 trials enrolled only hospitalized patients (including 3 with only intensive care unit patients). Risk of bias was low for 29/33 trials. Of 8495 patients who received convalescent plasma, 1997 died (23%), and of 7982 control patients, 1952 died (24%). The combined risk ratio for all-cause mortality was 0.97 (95% confidence interval: 0.92; 1.02) with between-study heterogeneity not beyond chance (I2 = 0%). The RECOVERY trial had 69.8% and the unpublished evidence 25.3% of the weight in the meta-analysis.

CONCLUSIONS

Convalescent plasma treatment of patients with COVID-19 did not reduce all-cause mortality. These results provide strong evidence that convalescent plasma treatment for patients with COVID-19 should not be used outside of randomized trials. Evidence synthesis from collaborations among trial investigators can inform both evidence generation and evidence application in patient care.

Evolution and Epidemic Spread of SARS-CoV-2 in Colombia: A Year into the Pandemic

Current efforts to understand the epidemiology, transmission dynamics and emergence of novel SARS-CoV-2 variants worldwide has enabled the scientific community to generate critical information aimed at implementing disease surveillance and control measures, as well as to reduce the social, economic and health impact of the pandemic. Herein, we applied an epidemic model coupled with genomic analysis to assess the SARS-CoV-2 transmission dynamics in Colombia. This epidemic model allowed to identify the geographical distribution, Rt dynamics and predict the course of the pandemic considering current implementation of countermeasures. The analysis of the incidence rate per 100,000 inhabitants carried out across different regions of Colombia allowed visualizing the changes in the geographic distribution of cases. The cumulative incidence during the timeframe March 2020 to March 2021 revealed that Bogotá (8063.0), Quindío (5482.71), Amazonas (5055.68), Antioquia (4922.35) and Tolima (4724.41) were the departments with the highest incidence rate. The highest median Rt during the first period evaluated was 2.13 and 1.09 in the second period; with this model, we identified improving opportunities in health decision making related to controlling the pandemic, diagnostic testing capacity, case registration and reporting, among others. Genomic analysis revealed 52 circulating SARS-CoV-2 lineages in Colombia detected from 774 genomes sequenced throughout the first year of the pandemic. The genomes grouped into four main clusters and exhibited 19 polymorphisms. Our results provide essential information on the spread of the pandemic countrywide despite implementation of early containment measures. In addition, we aim to provide deeper phylogenetic insights to better understand the evolution of SARS-CoV-2 in light of the latent emergence of novel variants and how these may potentially influence transmissibility and infectivity.

New insights into oxidative stress and immune mechanisms involved in age-related macular degeneration tackled by novel therapies

The prevalence of age-related macular degeneration (AMD) has increased in the last years. Although anti-VEGF agents have improved the prognosis of exudative AMD, dry AMD has still devastating effects on elderly people vision. Oxidative stress and inflammation are mechanisms involved in AMD pathogenesis and its progression. Molecular pathways involving epidermal growth factor receptor (EGFR), bone morphogenetic protein (BMP4) and the nuclear erythroid related factor 2 (Nrf2) are behind oxidative stress in AMD due to their participation in antioxidant cellular pathways. As a consequence of the disbalance produced in the antioxidant mechanisms, there is an activation of innate and adaptative immune response with cell recruitment, changes in complement factors expression, and modification of cellular milieu. Different therapies are being studied to treat dry AMD based on the possible effects on antioxidant molecular pathways or their action on the immune response. There is a wide range of treatments presented in this review, from natural antioxidant compounds to cell and gene therapy, based on their mechanisms. Finally, we hypothesize that alpha-1-antitrypsin (AAT), an anti-inflammatory and immunomodulatory molecule that can also modulate antioxidant cellular defenses, could be a good candidate for testing in AMD. This article is part of the special ssue on 'The Quest for Disease-Modifying Therapies for Neurodegenerative Disorders'.

A Year of Living Dangerously: Challenges and Recommendations for Safely Performing Ophthalmic Surgery During the COVID-19 Pandemic, from Start to Finish

The COVID-19 pandemic has forced all nations to take an active role in infection control incorporating recommendations and measures to control viral dissemination. The epidemiological impact is very diverse and dynamic, even within the same region. Scientific knowledge regarding SARS-CoV-2 continues to improve every day with protocols needing to be updated and adjusted on a regular basis. Ophthalmology is a medical specialty identified to be at high risk for several reasons: it has very close doctor-patient contact, the virus has been detected in tears, and the ocular surface serves as a gateway to developing the infection. We have reviewed the current information on SARS-CoV-2 in the ophthalmologic field and provide up-to-date recommendations to help create protocols that can adapt to the dynamic situation of ophthalmologic institutions, patient cases, economic situations and access to diagnostic tests. This paper outlines the main recommendations regarding the initial consultation and outpatient clinics, measures to apply in the operating room (OR), and suggestions for post-surgical controls. Triage, according to the patient’s conditions and eye pathology, reduction of the time the patient is at the institution, social distancing, correct use of personal protective equipment (PPE), barrier methods, hygiene, as well as other recommendations mentioned in this document, will allow physicians to take care of the visual health of the patients while reducing the impact of the COVID-19 pandemic.

Hypertension and the roles of the 9p21.3 risk locus: Classic findings and new association data

BACKGROUND

The band 9p21.3 contains an established genomic risk zone for cardiovascular disease (CVD). Since the initial 2007 Wellcome Trust Case Control Consortium study (WTCCC), the increased CVD risk associated with 9p21.3 has been confirmed by multiple studies in different continents. However, many years later there was still no confirmed report of a corresponding association of 9p21.3 with hypertension, a major CV risk factor, nor with blood pressure (BP).

THEORY

In this contribution, we review the bipartite haplotype structure of the 9p21.3 risk locus: one block is devoid of protein-coding genes but contains the lead CVD risk SNPs, while the other block contains the first exon and regulatory DNA of the gene for the cell cycle inhibitor p15. We consider how findings from molecular biology offer possibilities of an involvement of p15 in hypertension etiology, with expression of the p15 gene modulated by genetic variation from within the 9p21.3 risk locus.

RESULTS

We present original results from a Colombian study revealing moderate but persistent association signals for BP and hypertension within the classic 9p21.3 CVD risk locus. These SNPs are mostly confined to a 'hypertension island' that spans less than 60 kb and coincides with the p15 haplotype block. We find confirmation in data originating from much larger, recent European BP studies, albeit with opposite effect directions.

CONCLUSION

Although more work will be needed to elucidate possible mechanisms, previous findings and new data prompt reconsidering the question of how variation in 9p21.3 might influence hypertension components of cardiovascular risk.

Updates and Comparative Analysis of the Mitochondrial Genomes of Paracoccidioides spp. Using Oxford Nanopore MinION Sequencing

The mitochondrial genome of the Paracoccidioides brasiliensis reference isolate Pb18 was first sequenced and described by Cardoso et al. (2007), as a circular genome with a size of 71.3 kb and containing 14 protein coding genes, 25 tRNAs, and the large and small subunits of ribosomal RNA. Later in 2011, Desjardins et al. (2011) obtained partial assemblies of mitochondrial genomes of P. lutzii (Pb01), P. americana (Pb03), and P. brasiliensis sensu stricto (Pb18), although with a size of only 43.1 kb for Pb18. Sequencing errors or other limitations resulting from earlier technologies, and the advantages of NGS (short and long reads), prompted us to improve and update the mtDNA sequences and annotations of two Paracoccidioides species. Using Oxford Nanopore and Illumina read sequencing, we generated high-quality complete de novo mitochondrial genome assemblies and annotations for P. brasiliensis (Pb18) and P. americana (Pb03). Both assemblies were characterized by an unusually long spacer or intron region (>50 kb) between exons 2 and 3 of the nad5 gene, which was moderately conserved between Pb03 and Pb18 but not similar to other reported sequences, except for an unassigned contig in the 2011 assembly of Pb03. The reliability of the insert missing from previous mtDNA genome assemblies was confirmed by inspection of the individual Nanopore read sequences containing nad5 coding DNA, and experimentally by PCR for Pb18. We propose that the insert may aid replication initiation and may be excised to produce a smaller structural variant. The updated mtDNA genomes should enable more accurate SNP and other comparative or evolutionary analyses and primer/probe designs. A comparative analysis of the mtDNA from 32 isolates of Paracoccidioides spp., using the SNPs of the aligned mitochondrial genomes, showed groupings within the brasiliensis species complex that were largely consistent with previous findings from only five mitochondrial loci.

Alpha-1-antitrypsin ameliorates inflammation and neurodegeneration in the diabetic mouse retina

Diabetic retinopathy (DR) is the most common cause of blindness in the working age population. Early events of DR are accompanied by neurodegeneration of the inner retina resulting in ganglion cell loss. These findings together with reduced retinal thickness are observed within the first weeks of experimental DR. Besides, an inflammatory process is triggered in DR in which the innate immune response plays a relevant role. Alpha 1 antitrypsin (AAT), an inhibitor of serine proteases, has shown anti-inflammatory properties in several diseases. We aimed at evaluating the use of AAT to prevent the early changes induced by DR. Diabetic AAT-treated mice showed a delay on ganglion cell loss and retinal thinning. These animals showed a markedly reduced inflammatory status. AAT was able to preserve systemic and retinal TNF-α level similar to that of control mice. Furthermore, retinal macrophages found in the AAT-treated diabetic mouse exhibited M2 profile (F4/80⁺CD206⁺) together with an anti-inflammatory microenvironment. We thus demonstrated that AAT-treated mice show less retinal neurodegenerative changes and have reduced levels of systemic and retinal TNF-α. Our results contribute to shed light on the use of AAT as a possible therapeutic option in DR.

Possible neuroprotective role of P2X2 in the retina of diabetic rats

BACKGROUND

Purinergic receptors are expressed in different tissues including the retina. These receptors are involved in processes like cell growth, proliferation, activation and survival. ATP is the major activator of P2 receptors. In diabetes, there is a constant ATP production and this rise of ATP leads to a persistent activation of purinergic receptors. Antagonists of these receptors are used to evaluate their inhibition effects. Recently, the P2X2 has been reported to have a neuroprotective role.

METHODS

We carried out a study in groups of diabetic and non-diabetic rats (N = 5) treated with intraperitoneal injections of PPADS, at 9 and 24 weeks of diabetes. Control group received only the buffer. Animals were euthanized at 34 weeks of diabetes or at a matching age. Rat retinas were analyzed with immunohistochemistry and western blot using antibodies against GFAP, P2X2, P2Y2 and VEGF-A.

RESULTS

Diabetic animals treated with PPADS disclosed a much more extended staining of VEGF-A than diabetics without treatment. A lower protein expression of VEGF-A was found at the retina of diabetic animals without treatment of purinergic antagonists compared to diabetics with the antagonist treatment. Inhibition of P2X2 receptor by PPADS decreases cell death in the diabetic rat retina.

CONCLUSION

Results might be useful for better understanding the pathophysiology of diabetic retinopathy.

Genome Diversity, Recombination, and Virulence across the Major Lineages of Paracoccidioides

The Paracoccidioides genus includes two species of thermally dimorphic fungi that cause paracoccidioidomycosis, a neglected health-threatening human systemic mycosis endemic to Latin America. To examine the genome evolution and the diversity of Paracoccidioides spp., we conducted whole-genome sequencing of 31 isolates representing the phylogenetic, geographic, and ecological breadth of the genus. These samples included clinical, environmental and laboratory reference strains of the S1, PS2, PS3, and PS4 lineages of P. brasiliensis and also isolates of Paracoccidioides lutzii species. We completed the first annotated genome assemblies for the PS3 and PS4 lineages and found that gene order was highly conserved across the major lineages, with only a few chromosomal rearrangements. Comparing whole-genome assemblies of the major lineages with single-nucleotide polymorphisms (SNPs) predicted from the remaining 26 isolates, we identified a deep split of the S1 lineage into two clades we named S1a and S1b. We found evidence for greater genetic exchange between the S1b lineage and all other lineages; this may reflect the broad geographic range of S1b, which is often sympatric with the remaining, largely geographically isolated lineages. In addition, we found evidence of positive selection for the GP43 and PGA1 antigen genes and genes coding for other secreted proteins and proteases and lineage-specific loss-of-function mutations in cell wall and protease genes; these together may contribute to virulence and host immune response variation among natural isolates of Paracoccidioides spp. These insights into the recent evolutionary events highlight important differences between the lineages that could impact the distribution, pathogenicity, and ecology of Paracoccidioides. IMPORTANCE Characterization of genetic differences between lineages of the dimorphic human-pathogenic fungus Paracoccidioides can identify changes linked to important phenotypes and guide the development of new diagnostics and treatments. In this article, we compared genomes of 31 diverse isolates representing the major lineages of Paracoccidioides spp. and completed the first annotated genome sequences for the PS3 and PS4 lineages. We analyzed the population structure and characterized the genetic diversity among the lineages of Paracoccidioides, including a deep split of S1 into two lineages (S1a and S1b), and differentiated S1b, associated with most clinical cases, as the more highly recombining and diverse lineage. In addition, we found patterns of positive selection in surface proteins and secreted enzymes among the lineages, suggesting diversifying mechanisms of pathogenicity and adaptation across this species complex. These genetic differences suggest associations with the geographic range, pathogenicity, and ecological niches of Paracoccidioides lineages.

The Dynamic Genome and Transcriptome of the Human Fungal Pathogen Blastomyces and Close Relative Emmonsia

Three closely related thermally dimorphic pathogens are causal agents of major fungal diseases affecting humans in the Americas: blastomycosis, histoplasmosis and paracoccidioidomycosis. Here we report the genome sequence and analysis of four strains of the etiological agent of blastomycosis, Blastomyces, and two species of the related genus Emmonsia, typically pathogens of small mammals. Compared to related species, Blastomyces genomes are highly expanded, with long, often sharply demarcated tracts of low GC-content sequence. These GC-poor isochore-like regions are enriched for gypsy elements, are variable in total size between isolates, and are least expanded in the avirulent B. dermatitidis strain ER-3 as compared with the virulent B. gilchristii strain SLH14081. The lack of similar regions in related species suggests these isochore-like regions originated recently in the ancestor of the Blastomyces lineage. While gene content is highly conserved between Blastomyces and related fungi, we identified changes in copy number of genes potentially involved in host interaction, including proteases and characterized antigens. In addition, we studied gene expression changes of B. dermatitidis during the interaction of the infectious yeast form with macrophages and in a mouse model. Both experiments highlight a strong antioxidant defense response in Blastomyces, and upregulation of dioxygenases in vivo suggests that dioxide produced by antioxidants may be further utilized for amino acid metabolism. We identify a number of functional categories upregulated exclusively in vivo, such as secreted proteins, zinc acquisition proteins, and cysteine and tryptophan metabolism, which may include critical virulence factors missed before in in vitro studies. Across the dimorphic fungi, loss of certain zinc acquisition genes and differences in amino acid metabolism suggest unique adaptations of Blastomyces to its host environment. These results reveal the dynamics of genome evolution and of factors contributing to virulence in Blastomyces.

Dimorphic fungal pathogens including Blastomyces are the cause of major fungal diseases in North and South America. The genus Emmonsia includes species infecting small mammals as well as a newly emerging pathogenic species recently reported in HIV-positive patients in South Africa. Here, we synthesize both genome sequencing of four isolates of Blastomyces and two species of Emmonsia as well as deep sequencing of Blastomyces RNA to draw major new insights into the evolution of this group and the pathogen response to infection. We investigate the trajectory of genome evolution of this group, characterizing the phylogenetic relationships of these species, a remarkable genome expansion that formed large isochore-like regions of low GC content in Blastomyces, and variation of gene content, related to host interaction, among the dimorphic fungal pathogens. Using RNA-Seq, we profile the response of Blastomyces to macrophage and mouse pulmonary infection, identifying key pathways and novel virulence factors. The identification of key fungal genes involved in adaptation to the host suggests targets for further study and therapeutic intervention in Blastomyces and related dimorphic fungal pathogens.

Transglutaminase binding fusion protein linked to SLPI reduced corneal inflammation and neovascularization

BACKGROUND

To study the effect of topical administration of a fusion protein (PF-MC) made up of N-terminal portion of the protease inhibitor Trappin-2 (which is a substrate of transglutaminasa-2) and SLPI (protein with anti-inflammatory, anti-bacterial and anti-viral ability), in an animal model of corneal inflammation and angiogenesis.

METHODS

An alkali injury was produced with a filter paper of 3 mm with 1 N NaOH during 40 seconds on the right cornea of 36 male Sprague Dawley rats, under general anesthesia. Animals were divided into three groups according to treatment. Group 1 was treated with 10 ul of PF-MC (200 ug/ml; n = 12), Group 2, with 10 ul of SLPI (200 ug/ml; n = 12) and Group 3 was treated with buffer (10 ul; n = 12) topically administered four times a day for up to 7 days. Half of the animals were sacrificed at day 3 before making a re-epithelialization time analysis with fluorescein staining at 18 and 24 hours. In the remaining animals corneal opacity was studied and digital photographs were taken at day 7 before doing euthanasia. Eyes were processed for histology and immunofluorescence.

RESULTS

Corneal ulcerated area was significantly lower in PF-MC treated animals compared to SLPI and buffer-treated animals at 18 hours and 24 hours postinjury. A clear cornea and fundus red reflex was only found among PF-MC treated animals. Histological analysis revealed a stratified corneal epithelium with at least three layers in all PF-MC animals at day 7. In this group there was a reduced number of PMNs in the corneal stroma at 3 and 7 days of follow-up. Besides, corneal neovascularization was much more extended in SLPI and Buffer animals than in animals treated with PF-MC.

CONCLUSIONS

The binding of SLPI with Cementoin to transglutaminase seems to be an effective strategy to treat corneal inflammation and angiogenesis.

Genome update of the dimorphic human pathogenic fungi causing paracoccidioidomycosis

Paracoccidiodomycosis (PCM) is a clinically important fungal disease that can acquire serious systemic forms and is caused by the thermodimorphic fungal Paracoccidioides spp. PCM is a tropical disease that is endemic in Latin America, where up to ten million people are infected; 80% of reported cases occur in Brazil, followed by Colombia and Venezuela. To enable genomic studies and to better characterize the pathogenesis of this dimorphic fungus, two reference strains of P. brasiliensis (Pb03, Pb18) and one strain of P. lutzii (Pb01) were sequenced [1]. While the initial draft assemblies were accurate in large scale structure and had high overall base quality, the sequences had frequent small scale defects such as poor quality stretches, unknown bases (N's), and artifactual deletions or nucleotide duplications, all of which caused larger scale errors in predicted gene structures. Since assembly consensus errors can now be addressed using next generation sequencing (NGS) in combination with recent methods allowing systematic assembly improvement, we re-sequenced the three reference strains of Paracoccidioides spp. using Illumina technology. We utilized the high sequencing depth to re-evaluate and improve the original assemblies generated from Sanger sequence reads, and obtained more complete and accurate reference assemblies. The new assemblies led to improved transcript predictions for the vast majority of genes of these reference strains, and often substantially corrected gene structures. These include several genes that are central to virulence or expressed during the pathogenic yeast stage in Paracoccidioides and other fungi, such as HSP90, RYP1-3, BAD1, catalase B, alpha-1,3-glucan synthase and the beta glucan synthase target gene FKS1. The improvement and validation of these reference sequences will now allow more accurate genome-based analyses. To our knowledge, this is one of the first reports of a fully automated and quality-assessed upgrade of a genome assembly and annotation for a non-model fungus.

The fungal genus Paracoccidioides is the causal agent of paracoccidioidomycosis (PCM), a neglected tropical disease that is endemic in several countries of South America. Paracoccidioides is a pathogenic dimorphic fungus that is capable of converting to a virulent yeast form after inhalation by the host. Therefore the molecular biology of the switch to the yeast phase is of particular interest for understanding the virulence of this and other human pathogenic fungi, and ultimately for reducing the morbidity and mortality caused by such fungal infections. We here present the strategy and methods we used to update and improve accuracy of three reference genome sequences of Paracoccidioides spp. utilizing state-of-the-art Illumina re-sequencing, assembly improvement, re-annotation, and quality assessment. The resulting improved genome resource should be of wide use not solely for advancing research on the genetics and molecular biology of Paracoccidioides and the closely related pathogenic species Histoplasma and Blastomyces, but also for fungal diagnostics based on sequencing or molecular assays, characterizing rapidly changing proteins that may be involved in virulence, SNP-based population analyses and other tasks that require high sequence accuracy. The genome update and underlying strategy and methods also serve as a proof of principle that could encourage similar improvements of other draft genomes.

Diabetic retinopathy: could the alpha-1 antitrypsin be a therapeutic option?

Diabetic retinopathy is one of the most important causes of blindness. The underlying mechanisms of this disease include inflammatory changes and remodeling processes of the extracellular-matrix (ECM) leading to pericyte and vascular endothelial cell damage that affects the retinal circulation. In turn, this causes hypoxia leading to release of vascular endothelial growth factor (VEGF) to induce the angiogenesis process. Alpha-1 antitrypsin (AAT) is the most important circulating inhibitor of serine proteases (SERPIN). Its targets include elastase, plasmin, thrombin, trypsin, chymotrypsin, proteinase 3 (PR-3) and plasminogen activator (PAI). AAT modulates the effect of protease-activated receptors (PARs) during inflammatory responses. Plasma levels of AAT can increase 4-fold during acute inflammation then is so-called acute phase protein (APPs). Individuals with low serum levels of AAT could develop disease in lung, liver and pancreas. AAT is involved in extracellular matrix remodeling and inflammation, particularly migration and chemotaxis of neutrophils. It can also suppress nitric oxide (NO) by nitric oxide sintase (NOS) inhibition. AAT binds their targets in an irreversible way resulting in product degradation. The aim of this review is to focus on the points of contact between multiple factors involved in diabetic retinopathy and AAT resembling pleiotropic effects that might be beneficial.

Proliferative retinopathy and neovascularization of the anterior segment in female type 2 diabetic rats

BACKGROUND

To examine the presence of diabetic retinopathy in a female rat model of type 2 diabetes fed on a high-fat diet (HFD).

METHODS

Wistar rats were injected with streptozotocin (STZ) at the age of two days and fed on an HFD from eight weeks onwards. Five diabetic animals were euthanized at 110 weeks of disease, together with a control group of age-matched, non-diabetic animals. A group of diabetic animals at 57 weeks of disease was included for comparison. Cross sections of the rats' corneas, iris and retinas were histologically examined and analysed by immunohistochemistry and immunofluorescence, using glial-fibrillary-acidic-protein (GFAP), the vascular endothelial growth factor (VEGF) and the Von Willebrand factor (vWF). The trypsine digestive technique was used for the pericytes count.

RESULTS

Neovascularization was only found in the retinas, irises and corneas of the diabetic animals of 110 weeks of disease. There was also a significantly lower number of pericytes in these animals than in the controls.

CONCLUSION

The female rat model of type 2 diabetes fed on an HFD may prove useful in evaluating the mechanisms involved in diabetic retinopathy, together with strategies to reduce its severity.

Suramab, a novel antiangiogenic agent, reduces tumor growth and corneal neovascularization

PURPOSE

Oncological and ophthalmological diseases are increasingly treated with antiangiogenic agents. These agents have different intensities and duration of effects that should be considered to choose the most suitable therapy. Our purpose was to evaluate the synergistic effect of two drugs, jointly administered as a pharmaceutical compound, in two animal models.

METHODS

Corneal neovascularization was induced in three groups of nine white New Zealand rabbits, applying a filter paper disk soaked in 1 M NaOH on the central cornea (Ormerod et al., Invest Ophthalmol Vis Sci 30:2148-2153, 1989). Group one was treated immediately after injury with intravenous Suramab, compound of Bevacizumab + Suramin, and group two with intravenous Bevacizumab. A third group of non-treated rabbits was included as control group. Digital photographs were taken at days 9, 15, 21, and 35. Neovessel index (NVI) was calculated using the Image J Program. Neovessels formation was quantified and given a score from 0 to 4 to each quadrant according to the centripetal growth of the longest vessel. Colorectal animal model: 6- to 8-week-old male BALB/c mice were inoculated with cancer cells. Seven days after tumor inoculation, four groups of BALB/c mice were treated with intravenous Bevacizumab (n = 9); intravenous Suramin (n = 10); intravenous Suramab (n = 10); and intravenous saline solution (n = 4). Tumor growth was assessed twice weekly by caliper measurement.

RESULTS

The NVI was remarkably inferior in the group of rabbits treated with intravenous Suramab compared with controls after 35 days of follow-up. A greater inhibitory effect was obtained with Suramab compared to that obtained with Bevacizumab. Suramab significantly reduced tumor volume and prolonged survival of mice compared to controls.

CONCLUSIONS

Suramab strongly reduced neovascularization in a rabbit model of corneal angiogenesis and induced a potent antitumoral effect in mice.

One-year follow-up of epithelial corneal cell sheet allografts mounted on platelet poor plasma in rabbits

PURPOSE

To evaluate the usefulness of epithelial corneal sheets mounted on platelet poor plasma (PPP) for allograft transplantation of rabbits with total limbal stem cell deficiency (LSCD) and to prove its efficacy at 1 year after surgery.

METHODS

LSCD was induced in 21 female rabbits by mechanical keratectomy. To configure the grafts, limbal biopsies were taken from male rabbits and cells were cultured on a fibroblast feeder layer grown on clotted autologous PPP. After keratectomy, grafts were sutured over the stroma. Control groups consisted of no implant or an implant of clotted PPP. Rabbits were euthanized at 3 and 12 months. Corneas and cultured sheets were processed for histopathology and immunohistochemistry (K3/12 and K19). Gender analysis was performed at 4 and 7 months.

RESULTS

One rabbit had endophthalmitis, and another died of no apparent cause. The rest of the animals treated had no inflammation, showed a stratified epithelium, keratin 3/12 expression, and no expression of keratin 19. At 1 year, seven of eight rabbits showed no LSCD or corneal rejection signs. Y chromosomes were detected at 4 and 7 months postoperatively. All controls showed LSCD signs, erratic epithelium, and minimal cell differentiation; they revealed a slight expression of K3/12 and an expression of K19 in patchy patterns.

CONCLUSIONS

Allografts contributed to restoring a healthy eye surface without signs of graft rejection. This technique seems to be a promising procedure for bilateral ocular surface diseases and may be useful for new therapeutic strategies.

Regressed retinopathy of prematurity in children aged 5-10 years

Regressed retinopathy of prematurity (ROP) and its sequelae has been analysed in pre-term born children with a birth weight < 1500 g and/or < 33 weeks of gestational age, born in Stockholm during 1976-81. At the age of 5-10 years, we found that 134 of 528 preterm born children (25.4%) had been at departments of ophthalmology in Stockholm for various reasons. These children were re-examined and a good eye fundus information could be obtained in 105. Moderate and severe regressed ROP was found in 48 and 13 children, respectively. In the Stockholm area the frequency of children with severe ROP (earlier called cicatricial ROP) was 2.5% out of the above risk group of 528. Two children were blind from ROP (0.4%). Ten children had a visual acuity < or = 0.3 in the worse eye (1.9%) and 7 of them had ROP changes. Children with a birth weight < 1000 g had the highest frequency of ROP (severe 11.6% and moderate 18.6%) and ocular complications. The results show that preterm born children often present ocular complications, and therefore they need a close follow-up.

Advances in corneal stem-cell transplantation in rabbits with severe ocular alkali burns

PURPOSE

To evaluate the efficacy of autologous corneal epithelial sheet implantation in restoring transparency of rabbit corneas severely injured by alkaline and the effect of photocoagulation in arresting corneal neovessel ingrowth.

SETTING

Ophthalmology Department, School of Biomedical Sciences, Universidad Austral, Buenos Aires, Argentina.

METHODS

Limbal stem-cell deficiency (LSCD) was induced in 14 rabbits by alkali burns. A limbal cell biopsy was done in the contralateral eye, and the cells were cultured on a fibroblast feeder layer grown on autologous clotted platelet-poor plasma or commercial fibrin for 21 days. Anterior keratectomy was followed by suturing corneal cell sheets over the stroma. If regrowth of vessels occurred, argon laser photocoagulation was applied to them. Rabbits were killed at 30, 60, 90, 180, and 360 days and the corneas processed for histopathology and inmunohistochemistry.

RESULTS

A small (2.5 mm(2)) limbal biopsy achieved stem-cell replication in vitro. Corneal clarity and epithelial defects evolved with a trend toward improvement. There was a significant reduction in corneal neovascularization. Histology showed a multilayered stratified epithelium including several epithelial-like cells with clear cytoplasm in the deepest part. There were no signs of intraepithelial mucin cells on the implanted corneas. Immunohistochemical results showed expression of cytokeratins 3 and 12 in the central corneal epithelium and an absence of cytokeratin 19.

CONCLUSIONS

Autologous limbal epithelial cell transplantation improved the corneal surface in eyes with LSCD. Photocoagulation of neovessel ingrowth was effective over the 1-year follow-up. Results may facilitate the application of this technique in patients.

Comparative study of scientific publications in Ophthalmology and Visual Sciences in Argentina, Brazil, Chile, Paraguay and Uruguay (1995-2004)

PURPOSE

The study aimed to measure the scientific production in Ophthalmology and Vision (O&V) in Argentina, Brazil, Chile, Paraguay and Uruguay over a period of 10 years (1995-2004), in order to find out temporal evolution and variations in this field of research.

METHODS

PubMed / Medline was used to retrieve records on O&V research literature. The search strategy included keywords, country in the affiliation field and publication date. Data were extracted from each citation and recorded in a spreadsheet. Subsequent analysis focused on type and main topic of publication, journals where articles had been published, and evolution of research done on animals and humans.

RESULTS

A total of 1,216 citations were retrieved. Brazil had the largest number of authored publications with an average annual production of 82.4, followed by Argentina with 31.0, Chile 6.4, Uruguay 1.6, and Paraguay 0.2. The ratio of articles on O&V relative to publications involving Health Science ranged from 1.0 to 2.3. The frequency of publications almost tripled from 1995 to 2004. Research on humans showed a significant increase in Argentina and Brazil.

CONCLUSIONS

Results provide initial benchmarks on O&V publication rates in countries in South America that may be useful to follow research trends.

A mouse model of proliferative vitreoretinopathy induced by dispase

A proliferative vitreoretinopathy-like condition induced by intravitreal dispase injection in C57BL/6J mice was studied using ophthalmoscopic and histochemical procedures. The frequency of intravitreal hemorrhage, intravitreal spots, retinal folds and epiretinal membranes was scored by ophthalmoscopic examination at 1, 2, 4, 6 and 8 weeks after the injection. Intravitreal spots corresponded to free cells exhibiting F4/80 immunoreactivity, a macrophage/microglial marker. Retinal folds always appeared before an epiretinal membrane could be observed. Dispase-injected eyes always showed a much higher frequency of folds and membranes than saline-injected eyes. Folds and membranes appeared earlier and were more extensive in the presence of intravitreal hemorrhage than in its absence. Müller retinal cells exhibited significant changes in glial fibrillary acidic protein-immunoreactivity. This was absent in normal Müller cells but, in dispase-injected animals, it was expressed in radial processes at the site of retinal folds, later extending to the whole retina. Both epi- and subretinal membranes contained cells probably derived from Müller cells, since they exhibited co-localization of glial fibrillary acidic protein- and glutamine synthase immunoreactivities. F4/80 was also present in numerous cells within the retina, epi- and subretinal membranes. By contrast, the retinal pigment epithelium cell marker RPE65 was restricted to subretinal membranes. It can be concluded that dispase induced a proliferative vitreoretinopathy-like condition in mice, with a strong contribution of macrophage- and glial-derived cells.

Y1 receptor of neuropeptide Y as a glial marker in proliferative vitreoretinopathy and diseased human retina

The Y1 receptor of neuropeptide Y (NPY) has been demonstrated in glial cells of astrocytic lineage in vitro. We have studied the immunohistochemical expression of Y1 receptors in the glia of the diseased human retina, in tissue samples obtained after surgery for proliferative vitreoretinopathy. In this condition, glia and other cell types migrate and form epi- or subretinal membranes. Both diseased retinas (n = 8) and PVR membranes (n = 43) contained numerous Y1-immunoreactive cells. In the diseased retina, the Y1 antiserum labeled cells with the morphological radial pattern characteristic of Müller cells, whereas in the membranes, label appeared in a large population of elongate cells, measuring up to 250 microm. In both retina and membranes, double labeling demonstrated that the vast majority of Y1-immunoreactive cells were also labeled by a glial fibrillary acidic protein (GFAP) antibody, indicating their glial origin. Retinal regions devoid of GFAP immunoreactivity also lacked the Y1 label. None of these markers was detected in Müller cells of normal retina. Y1 immunoreactivity did not co-localize with smooth muscle actin immunoreactivity, a marker of myofibroblasts. Expression of Y1 receptors would characterize reactive and proliferating glial cells of the diseased retina and could perhaps be involved in the proliferation of injured glial cells causing regrowth of PVR membranes and the consequent secondary retinal detachments.

Perinatal factors associated with retinopathy of prematurity

The etiology of retinopathy of prematurity appears to be multifactorial. Introduction of new treatments in neonatal care may add new risk factors. We have analyzed the relationship between 42 perinatal factors and the development of retinopathy of prematurity in 78 infants with a birth weight < 1501 g and/or gestational age < 33 weeks. We have also applied a chronological analysis of the maximum and minimum pO2 and pCO2 values. Retinopathy of prematurity was seen in 37 of 78 infants (47.4%). Nineteen factors were found to be related to the development of retinopathy of prematurity. However, when step-wise logistic regression analysis was used, only birth weight, number of days of oxygen therapy and use of beta-blocking agents by the mother before birth were found to be associated with the development of retinopathy of prematurity. The results suggest that medication with beta blockers immediately before birth should be used cautiously.

Low-grade myopia in children with regressed retinopathy of prematurity

Myopia is a frequent sequelae of retinopathy of prematurity. The mechanism for myopia development in children born preterm is not well understood. From a group of 33 myopic preterm children we selected those who had regressed retinopathy and myopic values < or = 5 D. Seventeen children met our criteria. Of them, 10 patients could be re-examined. Factors related to myopia development were analyzed and compared to a control group of 12 children born fullterm with emmetropia or low hypermetropia, as well as another group of 10 fullterm children with myopic values < or = 5 D. The age of children ranged from 9 to 14 years in all groups. The mean birth weight in myopic premature children was 1249.3 g. Higher keratometric diopter values were found in myopic premature children than in emmetropic fullterm children (p < 0.05) and myopic fullterm children (p < 0.05). Increased axial length values were observed in myopic fullterm children when compared to myopic premature children (p < 0.05) In children born preterm the corneal refractive power seems to play a major role in myopia development.

Regressed retinopathy of prematurity: the relationship between clinical risk factors of the newborn period and regressed retinopathy of prematurity severity in a preterm born population of Stockholm county 1976-81

In a retrospective study, clinical risk factors of the neonatal period were correlated with the severity of regressed retinopathy of prematurity (ROP) in a population of preterm infants (bw less than 1500 g and or gestational age less than 33 weeks). At the age of 5-11 years 134 out of 528 preterm born infants (25.4%) were found to be under ophthalmic care. Reliable information on eye fundus status could be obtained in 105 of them. Regressed ROP was found in 61, the moderate form in 48 (9.1%) and the severe form in 13 (2.5%) patients. Twelve patients (2.3%) had visual acuity of less than 0.3 on the worst eye and two (0.4%) of these patients were blind from ROP. Twenty-four clinical factors of the newborn period were correlated with the severity of regressed ROP. The results suggest that long oxygen exposure in combination with other factors interfering with retinal vasotonus are associated with the degree of the disease developed.

Regressed retinopathy of prematurity and its sequelae in children aged 5-10 years

Regressed retinopathy of prematurity (ROP) and its sequelae were studied in children born prematurely (less than 1501 g birth weight and/or less than 33 weeks gestational age) in Stockholm county during 1976-81. Through various searches of the records at the different eye departments and other sources in Stockholm county we found that 134 out of a total of 528 premature babies (25.4%) had needed ophthalmic care for different reasons. They were re-examined and reliable information on the fundus could be obtained for 105 of them. The frequency of regressed ROP was 45.5%. Severe forms with vitreoretinal scarring and retinal traction were seen in 9.7% of cases and moderate forms with pigmentary changes and/or vitreoretinal interphase changes in 35.8%. The sequelae of regressed ROP were mainly reduction of visual acuity and myopia. Children with a birth weight below 1000 g and a gestational age less than 30 weeks presented the highest rate of regressed ROP (68.5% and 61.9%) and ocular abnormalities.

A population-based study of ocular abnormalities in premature children aged 5 to 10 years

We studied the prevalence of ocular abnormalities in 528 children born prematurely (less than 1,501-g birth weight, less than 33 weeks' gestational age, or both) in Stockholm County from 1976 to 1981. The control group consisted of 1,047 randomly selected full-term children. Through various searches of the ophthalmic records from the period of 1981 to 1986 of Stockholm County, we found that 134 of the 528 premature children (25.4%) and 121 of the 1,047 full-term children (11.5%) had needed ophthalmic care for different reasons. The prevalence of ocular abnormalities was much higher in premature children than in full-term children: reduced visual acuity of 20/33 or worse in the best eye (21 of 528 [4.0%] and one of 1,047 [0.1%]); myopia (33 of 528 [6.3%] and 18 of 1,047 [1.8%]); anisometropia of 1 diopter or greater (31 of 528 [5.9%] and 15 of 1,047 [1.5%]); strabismus (52 of 528 [9.9%] and 22 of 1,047 [2.1%]); and nystagmus (13 of 528 [2.4%] and one of 1,047 [0.1%]). Children with birth weight less than 1,000 g had the highest rates of ocular abnormalities. We conclude that visual and oculomotor development of premature children should be carefully examined.

Neuro-ophthalmological evaluation of patients with myelomeningocele and Chiari malformations

Twenty-eight patients (14 females and 14 males aged between four and 34 years) with myelomeningocele and Chiari malformations were examined neuro-ophthalmologically. All patients had been under proper neurosurgical care and no reduction of visual function was found that could be related to optic atrophy or other changes in the visual pathways. However, ocular motility disorders, including strabismus, were common, although no case of down-beat nystagmus was observed. Manifest strabismus was found in 11 patients. Esotropia with or without A-pattern was seen in nine patients. Spontaneous or gaze-related nystagmus and abnormal optokinetic nystagmus represented the most common disturbances of ocular motility. Abnormalities of horizontal eye-movements were more common than those of vertical eye-movements. Strabismus of the manifest type was combined with other ocular motility disturbances in most cases.

Neuro-ophthalmological findings in relation to CNS lesions in patients with myelomeningocele

Twenty-eight patients (14 male, 14 female; aged four to 34 years) with myelomeningocele were studied. Magnetic resonance imaging was used to determine the correlation between disturbances of ocular motility and the degree of hydrocephalus, tectal plate deformity and dislocation of the cerebellum and medulla oblongata. All patients had Chiari malformations. Strabismus and spontaneous nystagmus were strongly related mainly to the degree of hydrocephalus and to some extent to the amount of lower brainstem deformities. Ocular motility defects with regard to oblique muscle functions and horizontal and vertical gaze and saccadic control often correlated with lower brainstem lesions. Convergence defects correlated with deformities of the upper brainstem. However, these correlations were not valid in the individual patient; some had no strabismus and normal ocular motility, in spite of advanced hydrocephalus and Chiari malformations.

Prevalence of refractive errors and ocular motility disorders in 5- to 10-year-old Swedish children born prematurely or at full-term

Knowledge of the occurrence of visual and ocular problems in children is important when eye health care systems are designed. We have studied the prevalence of ocular changes in all children born prematurely during 1976-1981 in Stockholm county and compared the findings with those obtained in a random sample of full-term children from the same period and area.