Contact Lenses Loaded with Melatonin Analogs: A Promising Therapeutic Tool against Dry Eye Disease.

Melatonin analogs topically administered evoke a potent tear secretagogue effect in rabbits. This route of drug administration requires high drug concentration and frequent dosing due to its reduced ocular surface retention. Therefore, contact lenses (CLs) have emerged as an alternative drug-delivery system that prolongs drug retention in the cornea, improving its therapeutic performance. This study explores the in vitro ability of five commercially available hydrogel CLs to act as a delivery system for melatonin analogs and the in vivo secretagogue effect of melatonin analog-loaded CLs. We soaked CLs with melatonin or melatonin analog solutions (1 mM) for 12 h. Spectroscopic assays showed that IIK7-loaded CLs led to the inadequate delivery of this compound. Conventional hydrogel lenses loaded with agomelatine released more agomelatine than silicone ones (16-33% more). In contrast, the CLs of silicone materials are more effective as a delivery system of 5-MCA-NAT than CLs of conventional materials (24-29%). The adaptation of CLs loaded with agomelatine or 5-MCA-NAT in rabbits triggered a higher tear secretion than the corresponding eye drops (78% and 59% more, respectively). These data suggest that CLs preloaded with melatonin analogs could be an adequate strategy to combat aqueous tear deficient dry eye disease.

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.

Effect of Melatonin and Its Analogs on Tear Secretion.

Melatonin has been shown to enhance tear secretion associated with dinucleotide diadenosine tetraphosphate. This study investigated the isolated action of melatonin and its analogs, agomelatine, N-butanoyl-2-(2-methoxy-6H-isoindolo[2,1-a]indol-11-yl) ethanamine (IIK7), and 5-methoxycarbonylamino-N-cetyltryptamine (5-MCA-NAT) (10 µl at 100 µM), on tear secretion when applied topically in the rabbit cornea and its relationship with the melatonin MT1, MT2, and MT3/quinone reductase QR2 receptors. The results showed a significant increase in tear secretion, with a maximal effect at 60 minutes for the agonists (138.9% ± 6.5%, 128.9% ± 6.4%, and 120.0% ± 5.2%, respectively; P < 0.05; 100% control) but not for melatonin (101.6% ± 7.9%; P > 0.05). Agonist action was tested combined with the antagonists DH97 (MT2 selective), prazosin (MT3/QR2 inhibitor), and luzindole (nonselective MT membrane receptor) (10 µl at 100 µM). DH97 reversed the effect of agomelatine, IIK7, and 5-MCA-NAT up to 30.85% ± 7.6%,108% ± 7.2%, and 87.01% ± 7.6%, respectively (P < 0.05; 100% control). Luzindole antagonized agomelatine and 5-MCA-NAT up to 67.35% ± 7.6% and 92.12% ± 8%, respectively (P < 0.05). Prazosin only reversed 5-MCA-NAT action up to 84.2% ± 7.7% (P < 0.05). These results suggest different pathways for the agonists to act through MT membrane receptors. Therefore, agomelatine, IIK7, and 5-MCA-NAT act through MT membrane receptors as secretagogues of tear secretion, and these analogs could be considered excellent therapeutic candidates for dry eye treatment. SIGNIFICANCE STATEMENT: Currently, dry eye with aqueous deficit is treated by adding artificial tears palliatively. This study shows that topical installation of three melatonin analogs (agomelatine, IIK7, and 5-MCA-NAT), but not melatonin, in therapeutic doses in the rabbit cornea significantly increases tear production, acting through different melatonin membrane receptor subtypes. Therefore, this study suggests that melatoninergic compounds could be considered excellent therapeutic candidates for dry eye treatment and ocular surface diseases occurring with a reduction in tear production.

Diquafosol Delivery from Silicone Hydrogel Contact Lenses: Improved Effect on Tear Secretion.

PURPOSE: The aim of this study was to evaluate the ability to uptake and to deliver diquafosol from commercial contact lenses (CLs) and its effect on tear secretion. METHODS: For both in vitro and in vivo experiments, two commercial silicone hydrogel (Si-Hy) CLs (comfilcon A and balafilcon A) were used. The CLs were soaked overnight for 12 h in diquafosol solution and control CLs were soaked in saline solution (NaCl 0.9%). The CLs were introduced into a new well container with 1 mL of saline solution, and aliquots of 100 µL were extracted at different times during a period of 6 h to measure the diquafosol release. For in vivo experiments, nine male New Zealand white rabbits were used. CLs soaked in diquafosol were inserted in the eye and compared with control CLs and diquafosol topical instillation. Schirmer's tests were performed to evaluate tear secretion and diquafosol release at different times during the 6-h period. RESULTS: For in vitro experiments, the largest amount of diquafosol was released during the first 24 h for both CL materials under study, without statistical differences between them (P < 0.05). The topical application showed the maximum release at 1 min after instillation, meanwhile the release from both CL materials was at 30 min of insertion. The effect on tear secretion was higher with CL delivery compared with topical instillation (P < 0.05), being 300 min for both CLs and 90 min for topical application. CONCLUSION: The use of CLs increases the residence time of diquafosol on the ocular surface with a concomitant enhancement in tear secretion during longer periods.

El bosque tropical seco en riesgo: Conflictos entre uso agropecuario, desarrollo turístico y provisión de servicios ecosistémicos en la Costa de Jalisco, México / The dry tropical forest at risk: Conflicts between agricultural and cattle use, turism development, and provision of ecosystemic services in the Coast of Jalisco, Mexico / O bosque tropical seco em risco: Conflitos entre uso agropecuario, desenvolvimento turístico e provisão de serviços ecossistêmicos na Costa de Jalisco, México

El bosque tropical seco (BTS) es un ambiente de alto valor ecológico y en la región del Pacífico mexicano cubre extensas áreas. La Reserva de la Biosfera Chamela-Cuixmala, Jalisco, México, protege poco más de 13000ha de este ecosistema. No hay comunidades humanas dentro de la reserva, pero en su zona aledaña la mayor parte de las tierras pertenecen a campesinos ejidatarios, y en la región colindante con el mar existen hoteles, casas de playa y otras facilidades turísticas. Con el fin de estudiar las relaciones entre la sociedad y el BTS, el presente trabajo analiza 1) aspectos de la historia ambiental de la región, 2) las visiones de los campesinos sobre el uso y transformación de este ecosistema, y 3) las unidades turísticas y la provisión de servicios ecosistémicos. Históricamente la región se pobló lentamente y los bosques se han visto como ambientes difíciles para el trabajo productivo. El reparto agrario y las políticas públicas han sido los principales motores de la transformación de los bosques. A pesar de ello aun existe una cobertura forestal de 50-80% en las tierras campesinas. El desarrollo turístico ha sido lento a pesar del alto potencial que se le ha dado desde hace décadas. La zona se encuentra en riesgo debido a proyectos turísticos de gran envergadura que pueden ocasionar graves deterioros de los ecosistemas y de sus capacidades de proveer servicios.

The tropical dry forest (TDF) constitutes an environment of a high ecological value and covers extensive areas in the Mexican Pacific. The Biosphere Reserve of Chamela-Cuixmala, in Jalisco, México, protects over 13000ha of this ecosystem. There are no human communities within the Reserve, but in its neighboring area most of the land belongs to farmers (ejidatarios), while in the coastal zone there are hotels, beach houses and other touristic facilities. In order to study the relations between society and the TDF, this work analyzes 1) aspects of the environmental history of the region, 2) the visions of farmers about the use and transformation of this ecosystem, and 3) the touristic units and the provision of ecosystemic services. Historically, the region was slowly populated and forests have been seen as difficult environments for productive labor. The agrarian reform land distribution and public policies have been the main drivers of forest transformation. Despite of this, there is still a 50-80% forest cover in farmers land. The touristic development has been slow in view of the high potential it has had for decades. The zone is currently at risk due to large touristic projects that can produce severe deterioration of the ecosystems and their service-providing capacities.

O bosque tropical seco (BTS) é um ambiente de alto valor ecológico e na região do Pacifico mexicano cobre extensas áreas. A Reserva da Biosfera Chamela-Cuixmala, Jalisco, México, protege pouco mais de 13000 ha deste ecossistema. Não há comunidades humanas dentro da reserva, mas na sua zona aledanha a maior parte das terras pertencem a camponeses ejidatarios, e na região colindante com o mar existem hoteis, casas de praia e oturas facilidades turísticas. Com o fim de estudar as relações entre a sociedade e o BTS, o presente trabalho analisa 1) aspectos da historia ambiental da região, 2) as visões dos camponeses sobre o uso e transformação deste ecossistema, e 3) as unidades turísticas e a provisão de serviços ecossisêmicos. Históricamente a região se povuou lentamente e os bosques tem sido vistos como ambientes difíceis para o trabalho produtivo. A repartição agrária e as políticas públicas tem sido os principais motores da transformação dos bosques. A pesar disto ainda existe uma cobertura florestal de 50-80% nas terras camponesas. O desenvolvimento turístico tem sido lento a pesar do alto potencial que se lhe tem dado desde faz décadas. A zona se encontra em risco devido a projetos turísticos de grande envergadura que podem ocasionar graves deterioros dos ecossistemas e de suas capacidades de prover serviços.

Therapeutic targets in dry eye syndrome.

Dry eye is a multifactorial disease of the tears and the ocular surface that manifests with a wide variety of signs and symptoms. It is prevalent in about 33% of the population worldwide. Due to the importance of the pathology, new tests, drugs and technologies have been developed to assist the diagnosis, management and follow-up of the disease. Current available therapies try to alleviate symptoms and to reduce signs in order to restore the ocular surface. Depending on the etiology of the pathology it is possible to use lubricants, secretagogues, biological tear substitutes or antiinflammatory drugs, either independently or combined. Nowadays, the therapies under clinical trial are devoted to stimulating tear components (e.g., diquafosol, a P2Y receptor agonist), or mucin secretion (e.g., rebamipide, an amino acid analogue of quinolinone). Others include gefarnate, a water-insoluble terpene fatty acid that contributes to restoring mucins on the ocular surface, or cevimeline, an oral cholinergic agonist that reduces the symptoms associated with dry eye. Other potential compounds described in patents are in a lower phase of drug development. These compounds come from different families of therapies, and among others, can be found in the form of steroidal and nonsteroidal antiinflammatory agents, vitamins A and D, neurotransmitters and neuropeptides.