Preliminary study of rabbits as an animal model of mammalian eye transplantation and literature review / Estudo preliminar de coelhos como modelo animal para transplante de olho em mamíferos e revisão da literatura

ABSTRACT Purpose: To describe an innovative animal model of eye transplantation used in rabbits. Methods: six Dutch-belted male rabbits were submitted to lateral orbitotomy in the right eye, wide retrobulbar anatomy exposure, dissection of the structures, identification and distal section of the optic nerve followed by anastomosis either by vicryl (group 1) or fibrin glue (group 2). Electroretinography recording was performed before the section of the optic nerve and every 30 seconds after, to monitor the function of retina. Left eye was used as control group. Results: After optic nerve resection and anastomosis, stable ERG amplitude of the right eye was lost after 302 seconds in group 1 and after 296 seconds on group 2. Left eye kept longer stable ERG amplitude curves. Conclusions: The animal model of whole eye transplantation was effective in describing a novel technique to be used in rabbits, with success of the anatomic procedure. Further studies will clarify the best anastomosis methods and maintenance of function of the receptor organ. Translational relevance: this animal model of whole eye transplantation provides a novel perspective for blind patients and the research models, since we describe a novel mammal animal model. This model can be used as basis of a human model of whole eye transplantation in future studies.

RESUMO Objetivo: Descrever uma técnica cirúrgica inovadora para transplante de olho em um modelo animal em coelhos. Métodos: Seis coelhos machos com Dutch Belted foram submetidos à orbitotomia lateral do olho direito, com ampla exposição da anatomia retrobulbar, dissecção do cone muscular, exposição e secção distal do nervo óptico seguida de anastomose por vicryl (Grupo 1) ou cola de fibrina (Grupo 2). O registro da eletrorretinografia foi realizado antes da secção do nervo óptico e a cada 30 segundos após, para monitorar a função da retina. O olho esquerdo foi usado como grupo controle. Resultados: Após a ressecção do nervo óptico, a estabilidade da amplitude da eletrorretinografia foi perdida no olho direito após 302 segundos no Grupo 1 e após 296 segundos no Grupo 2. O olho esquerdo manteve eletrorretinografia estável por períodos mais longos. Conclusão: O modelo animal de transplante total de olho foi eficaz em descrever uma nova técnica cirúrgica para ser utilizada em laboratório com coelhos, com sucesso do procedimento anatômico. Novos estudos esclarecerão os melhores métodos de anastomose e manutenção da função do órgão receptor.

Molecular mechanisms of topical anti-inflammatory effects of lipoxin A(4) in endotoxin-induced uveitis.

Lipoxin A(4) (LXA(4)) is a lipid mediator that plays an important role in inflammation resolution. We assessed the anti-inflammatory effect of LXA(4) on endotoxin-induced uveitis (EIU) in rats. The inflammatory cell number and levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), prostaglandin E(2) (PGE(2)), and protein, as well as expression of cyclooxygenase-2 (COX-2) and vascular endothelial growth factor (VEGF), in the anterior chamber of the eye were determined 24 h after lipopolysaccharide (LPS; 200 mug/paw) intradermal injection. The immunohistochemical reactivities of nuclear factor-kappaB (NF-kappaB) and c-Jun were also examined. Topical LXA(4) (1-10 ng/eye) pretreatment decreased the number of inflammatory cells and the protein leakage into the aqueous humor (AqH). In addition, topical LXA(4) (10 ng/eye) inhibited the LPS-induced production of IL-1beta, TNF-alpha, and PGE(2), and expression of COX-2 and VEGF. A decreased activation of NF-kappaB and c-Jun was also found in LXA(4)-treated eyes. It is very interesting that an anti-inflammatory effect was achieved even when LXA(4) (10 ng/eye) was applied topically after LPS challenge, as indicated by the reduction in the cellular and protein extravasations into the AqH. Moreover, topical treatment of corticosteroid prednisolone (200 mug/eye) beginning before or after LPS injection reduced all of the molecular and biochemical alterations promoted on EIU rats in an efficacy similar to that of LXA(4). Together, the present results provide clear evidence that pharmacological activation of LXA(4) signaling pathway potently reduces the EIU in rats. Therefore, LXA(4) stable analogs could represent promising agents for the management of ocular inflammatory diseases.

Preventive and therapeutic anti-inflammatory effects of systemic and topical thalidomide on endotoxin-induced uveitis in rats.

The present study examined the outcomes of systemic or topical treatment with thalidomide, a compound that possesses anti-inflammatory, immunomodulatory and anti-angiogenic properties, in rats subjected to endotoxin-induced uveitis (EIU). The effects of thalidomide were evaluated on endotoxin-induced leucocyte and protein infiltration and also on the production of interleukin (IL)-1beta and tumour necrosis factor (TNF)-alpha in rat aqueous humour (AqH). Moreover, the actions of thalidomide were assessed on the cyclooxygenase (COX)-2 and inducible nitric oxide synthase (iNOS) protein expression in retinal tissue. EIU was produced by a hindpaw injection of lipopolysaccharide (LPS), in male Wistar rats. Thalidomide (5, 25 and 50 mg/kg) was administered orally 1 h before LPS injection. In another set of experiments, to evaluate the therapeutic efficacy, 5% thalidomide was applied topically to both eyes at 6, 12 and 18 h after LPS administration. The oral pre-treatment with thalidomide decreased, in a dose-dependent manner, the number of inflammatory cells, the protein concentration, and the levels of IL-1beta and TNF-alpha in the AqH. Similar results were found in the AqH of rats that received a topical application of thalidomide. Furthermore, oral (50 mg/kg) and local (5%) thalidomide treatment also reduced expression of the pro-inflammatory proteins COX-2 and iNOS in the posterior segment of the eye. Thalidomide exhibited marked preventive and curative ocular effects in EIU in rats, a property that might be associated with its ability to inhibit the production of inflammatory cytokines and the expression of COX-2 and iNOS. This assembly of data provides additional molecular and functional insights into beneficial effects of thalidomide as an agent for the management of ocular inflammation.