The role and therapeutic potential of melatonin in age-related ocular diseases

The eye is continuously exposed to solar UV radiation and pollutants, making it prone to oxidative attacks. In fact, oxidative damage is a major cause of age-related ocular diseases including cataract, glaucoma, age-related macular degeneration and diabetic retinopathy. Since the nature of lens cells, trabecular meshwork cells, retinal ganglion cells, retinal pigment epithelial cells and photoreceptors is post-mitotic, autophagy plays a critical role in their cellular homeostasis. In age-related ocular diseases, this process is impaired, thus, oxidative damage becomes irreversible. Other conditions such as low- grade chronic inflammation and angiogenesis also contribute to the development of retinal diseases (glaucoma, age-related macular degeneration and diabetic retinopathy). As melatonin is known to have remarkable qualities such as antioxidant/antinitridergic, mitochondrial protector, autophagy modulator, anti-inflammatory and anti-angiogenic, it can represent a powerful tool to counteract all these diseases. The present review analyzes the role and therapeutic potential of melatonin in age-related ocular diseases, focusing on nitro-oxidative stress, autophagy, inflammation and angiogenesis mechanisms

Presbyopia: An outstanding and global opportunity for early detection of pre-frailty and frailty states

Depto. de Optometría y VisiónUnidad Docente de Inmunología, Oftalmología y ORLFac. de Óptica y OptometríaTRUEEuropean Union's Horizon 2020 programmeUniversidad Complutense de Madrid (España)Banco Santander (España)pu

Sobreexpresión del receptor P2Y2 tras su silenciamiento durante el proceso de cicatrización corneal

Diadenosine polyphosphates are a family of dinucleotides with relevant properties in the eye and in other tissues. Diadenosine polyphosphates can activate P2Y and P2X receptors present on the ocular surface, anterior segment and retina. In the cornea, the presence of a P2Y2, P2Y4 and P2Y6 receptor has been identified. Both diadenosine polyphosphates and other purinergic agonists modified corneal wound healing depending on the receptor that is activated by these substances. To confirm the involvement of the P2Y2 receptor in the wound healing process after the challenge with Ap4A, we have designed siRNA against P2Y2 receptor. We have observed that P2Y2 is localized in the most external layer of the corneal epithelium. The pre-treatment with siRNA produced a disappearance of the receptor at 12 and 24 hours after the wound, being the location for P2Y2 restored 36 hours after the wound. We have also observed that in half of the tested corneas, there was an increase in the P2Y2 expression after silencing compared to control and Ap4A treated corneas, being this receptor localized both in corneal epithelium and stroma.Los diadenosina polifosfatos son una familia de dinucleótidos con gran relevancia en las propiedades del ojo y de otros tejidos. Estos diadenosina polifosfatos pueden activar los receptores P2Y y P2X presentes en la superficie ocular, en el segmento anterior y en la retina. En la cornea, se ha identificado la presencia de receptores P2Y2, P2Y4 y P2Y6. Tanto los diadenosina polifosfatos como los receptores purinérgicos modifican el proceso de cicatrización corneal dependiendo del tipo de receptor activado por los distintos dinucleótidos. Para localizar el receptor P2Y2 en córneas lesionadas y tratadas con Ap4A en presencia o ausencia de un siRNA para el receptor P2Y2, hemos realizado un ensayo de inmunohistoquímica. Hemos observado que el receptor P2Y2 se localiza en el epitelio tras la lesión corneal y el consecuente tratamiento con Ap4A. El pre-tratamiento con el siRNA produce la desaparición de la señal para este receptor tanto a las 12 como a las 24 horas de la lesión corneal, siendo la localización de este receptor P2Y2 recuperada a las 36 horas de la lesión en presencia del siRNA. Además, hemos observado que en la mitad de las córneas analizadas, existía un incremento en la expresión del receptor P2Y2 tras el silenciamiento del mismo comparado con las córneas control y con las tratadas con Ap4A, localizando la presencia de este receptor tanto en el epitelio como en el estroma corneal

Corneal Re-epithelialization Stimulated by Diadenosine Polyphosphates Recruits RhoA/ROCK and ERK1/2 Pathways

Purpose. To investigate the role of ERK1/2 and RhoA/ROCK intracellular pathways in the modification of corneal re-epithelialization when stimulated by the diadenosine polyphosphates Ap4A and Ap3A. Methods. In wounded confluent SIRC (Statens Seruminstitut rabbit cornea) cell monolayers and in the presence or absence of Ap4A or Ap3A 100 μM, a battery of P2 receptor antagonists and inhibitors of tyrosin kinases, MAPK, and cytoskeleton pathways (AG1478 100 μM, U0126 100 μM, Y27632 100 nM, and (−)-blebbistatin 10 μM; n = 8 each) were assayed. Also, the activation of ERK1/2 and ROCK-I was examined by Western blot assay after treatment with Ap4A and Ap3A (100 μM), with or without suramin, RB-2, U0126, and Y27632. The intracellular distribution of pERK and ROCK-I was examined in the presence of Ap4A or Ap3A (100 μM) with U0126 and Y27632 (100 nM). Results. In the presence of Ap4A, U0126, Y27632, AG1478, and (−)-blebbistatin, reduced the migration rate compared to the effect of Ap4A alone (P < 0.0001, P < 0.001, P < 0.01, and P < 0.1 versus Ap4A, respectively). In the presence of Ap3A 100 μM, U0126 and Y27632 accelerated the migration rate when compared with the effect of Ap3A alone, whereas AG1478 and (−)-blebbistatin (P < 0.0001 versus Ap3A) slowed the migration rate. Western blot assays demonstrated that both dinucleotides activated the ERK1/2 pathway but only Ap4A activated the ROCK-I pathway. The intracellular distribution of pERK1/2 and ROCK-I reflected cross-talk between these two pathways. Conclusions. The activation of the Ap4A/P2Y2 receptor, accelerates corneal epithelial cell migration during wound healing with the activation of MAPK and cytoskeleton pathways, whereas activation of the Ap3A/P2Y6 receptor signals only the MAPK pathway

¿Procesamiento de proteínas en Plasmodium falciparum?

human and animal malaria, are characterized by an extreme high A+T content and an associated abundant low complexity inserts within their proteins. The enzyme glucose-6-phosphate dehydrogenase-6-phosphogluconolactonase (G6PD- 6PGL) found in Plasmodium species has unique structural and bifunctional characteristics. Here, we report the expression analysis of P. faciparum G6PD- 6PGL along the intraerythrocytic cycle by immunological analysis with antibodies raised against its N- and C- terminal domains. The pattern modification of band sizes at the different stages of parasite development suggest intracellular protein processing involving the cleavage of the native bifunctional form to produce two main fragments. In vitro RNA-mediated PfG6PD-6PGL gene silencing, studied along short-term parasite development also revealed the apparent intracellular protein modification dependent on the parasite stage. Fragment sizes were consistent with separating both catalytic functions of the enzyme. The proteolytic machinery underlying this specific PfG6PD-6PGL proccesing is still unknown in P. falciparum but suggests the existence of distinctive mechanisms in the parasite to deal with unique protein structures of essential function resulting from its genome evolution.Los genomas de los organismos del género Plasmodium, agente causante de la malaria humana y animal, se caracterizan por un alto contenido en A+T e inserciones de baja complejidad en sus proteínas. La enzima glucosa-6-fosfato deshidrogenasa- 6-fosfogluconolactonasa (G6PD-6PGL) de las especies de Plasmodium posee unas características estructurales y bifuncionales únicas. En el presente trabajo analizamos la expresión de la G6PD-6PGL de P. faciparum a lo largo del ciclo intraeritrocítico mediante análisis inmunológico con anticuerpos frente a sus dominios N- y C- terminal. La modificación del tamaño del patrón de bandas en los diferentes estadios del desarrollo del parásito sugiere un procesamiento intracelular de la proteína que implicaría que la forma nativa bifuncional genera dos fragmentos principales. El silenciamiento in vitro del gen PfG6PD-6PGL, mediante ARN de interferencia, durante el desarrollo a corto plazo del parásito, también reveló la aparente modificación intracelular de la proteína dependiente del estadio de su ciclo vital. El tamaño de los fragmentos fue consistente con la separación de las dos funciones catalíticas de la enzima. Aunque en P. falciparum no se ha identificado la maquinaria proteolítica de este procesamiento específico de PfG6PD- 6PGL, nuestros resultados sugieren la existencia de mecanismos especializados para el procesamiento intracelular de este tipo de proteínas de estructura única y de función esencial, y que han podido aparecer como consecuencia de la particular evolución de su genoma

Therapeutic potential of topical administration of siRNAs against HIF-1α for corneal neovascularization.

Given the implications of the problem of neovascularization on ocular health, as well as the growth in the number of cases, the purpose of the present study has been testing the efficacy of siRNAs (small interfering RNA) designed to silence Hypoxia Inducible Factor -1α (HIF-1α) and to demonstrate that their use stops neovascularization in a model of corneal burn. Corneal wounds in the limbic zone were made in the eyes of New Zealand white rabbits. Topical applications of siRNAs were done the next day to the wound for four consecutive days and eyes were examined with a slit lamp. Evaluation of neovascularization progress was done by analyzing images by ImageJTM and to determine the neovascular area in Matlab ® was used. At the same time, a rabbit corneal cell line was used for in vitro study of hypoxia exposure and Western blot analysis of the cell's extracts were done. Under normal cell culture oxygenation, the expression of HIF-1α was lower than that observed under hypoxic conditions. After 2 h of hypoxia, there was a significant increase in the HIF-1α expression, effect that was maintained up to 6 h. The increased in HIF-1α was mimicked by a cell permeable prolyl-4-hydroxylase inhibitor. Cobalt chloride showed no capacity to increase HIF-1α in vitro. The effect of three different siRNA on HIF-1α was tested after 4 h of hypoxia. siRNA#1 was able to silence 80% of HIF-1α expression, siRNA#2 and siRNA#3 reduce the expression in 45% and 40% respectively. In addition, the three siRNA were tested in a corneal model of neovascularization. scrambledsiRNA#2 was the most effective inhibitor of blood vessel production, followed by siRNA#3 and siRNA#1. Compared to the scrambled siRNA (100% of blood vessel generation), siRNA#2 blocked the presence of blood vessels by 83 ± 2%, siRNA#3 inhibited 45 ± 7% and siRNA#1 only inhibited 18 ± 5%. The necessary time to observe the 50% of effect showed values of NV50 of 10.2 ± 2.4 days for the scrambled siRNA, 9.1 ± 1.4 for siRNA#1, 6.5 ± 1.85 for siRNA#2 and 4.8 ± 1.8 days for siRNA#3. In conclusion, the topical application of siRNA towards HIF-1α seems to be an effective and reliable method to stop neovascularization.This work was supported by a grant from Ministerio de Ciencia e Innovación (SAF2010-16024 and SAF2013-44416-R) and RETICS (RD12/0034/0003), and a grant from the Instituto de Salud Carlos III of Spain and Fondo Europeo de Desarrollo Regional (FEDER, “Una manera de hacer Europa”) (FIS-FEDER PI07-1168 to J. Mateo)S

Dual-mode gold nanoparticle-based method for early detection of Acanthamoeba

Acanthamoeba keratitis is an aggressive and rapidly progressing ocular pathology whose main risk factor is the use of contact lenses. An early and differential diagnosis is considered the main factor to prevent the progression and improve the prognosis of the pathology. However, current diagnosis techniques require time, complex and costly materials making an early diagnosis challenging. Thus, there is a need for fast, accessible, and accurate methods for Acanthamoeba detection by practitioners for timely and suitable treatment and even for contact lens user as preventive diagnosis. Here, we developed a dual-mode colorimetric-based method for fast, visual, and accurate detection of Acanthamoeba using gold nanoparticles (AuNPs). For this strategy, AuNPs were functionalized with thiolated probes and the presence of target Acanthamoeba genomic sequences, produce a colorimetric change from red to purple. This approach allows the detection of 0.02 and 0.009 μM of the unamplified Acanthamoeba genome by the naked eye in less than 20 min and by color analysis using a smartphone. Additionally, real samples were successfully analyzed showing the potential of the technology considering the lack of point-of-care tools that are mostly needed.This work was supported by an industrial project (ND2017/BMD7676) granted by the community of Madrid.info:eu-repo/semantics/publishedVersio

Optimization of a Rabbit Dry Eye Model Induced by Topical Instillation of Benzalkonium Chloride

Purpose. To optimize a rabbit dry eye model induced by topical instillation of benzalkonium chloride (BAC), reduce the days of instillation of the original model by increasing the concentration of BAC from 0.1% to 0.2%. Materials and Methods. An experimental, prospective, and randomized study was performed on 10 male New Zealand white rabbits, divided into two groups, considering both eyes: 5 rabbits as control (n = 10) and 5 rabbits with 0.2% BAC treatment (n = 10). Saline solution (control) and 0.2% BAC were instilled for 5 consecutive days, twice daily. Tear secretion with and without anesthesia, tear breakup time, tear osmolarity, corneal staining, conjunctival hyperemia, density of goblet cells, height of mucin cloud, and transcript levels of IL-6 were measured before and after the treatment. Results. After the instillation of 0.2% BAC for 5 consecutive days, there was a significant increase in tear secretion without anesthesia (P < 0.001), corneal staining (P < 0.001), conjunctival hyperemia (P < 0.001), and levels of IL-6 mRNA (P = 0.005) compared to the control group. Conversely, there was a decrease in tear secretion with anesthesia (P < 0.001), tear breakup time (P = 0.007), tear osmolarity (P < 0.001), density of goblet cells (P < 0.001), and height of mucin cloud (P < 0.001). Conclusions. )e topical instillation of 0.2% BAC for 5 consecutive days, twice daily, was a proper procedure to induce a rabbit dry eye model, reducing the number of days of instillation compared to the original model (14 days)