Pharmacokinetics, electrophysiological, and morphological effects of the intravitreal injection of mycophenolic acid in rabbits

Insights From the Eye for Patients With Kidney Transplant

The eye and the kidney share structural and developmental similarities on a cellular and clinical level, and they are often affected by the same disease processes. Performing an eye exam to look for signs of conditions such as hypertension and diabetes can provide a helpful window into the health of the kidney. Patients with kidney transplants (KT) are a unique population that require close monitoring. These patients are maintained on a number of immunosuppressive medications and may face complications such as medication side effects, infections, and graft rejection. Patients with KT are at higher risk of both infectious and noninfectious eye conditions related to underlying systemic disease or use of immunosuppressive medications. Screening for eye conditions is important because preserving visual function is integral to quality of life, and also because the eye exam can help with early detection and treatment of systemic conditions. Here we describe some of the common eye findings and conditions in patients with KT. We recommend that patients with KT receive annual eye exams, and we hope that the information provided here can help nephrologists become more familiar with eye findings and identify situations where a referral to ophthalmology is warranted.

Intravitreal lupeol: A new potential therapeutic strategy for noninfectious uveitis

Lupeol is a pentacyclic triterpene with known anti-inflammatory effects. However, its role in the treatment of noninfectious uveitis has not been explored. This work investigated anti-inflammatory activity of lupeol in ocular tissues with in vitro and in vivo models. First, we evaluated the effect of lupeol (100 µM) on inflammatory response induced by lipopolysaccharide (LPS) in retinal pigment epithelium cells (ARPE-19) by measuring levels of released interleukins (IL-6 and IL-8). Then, we investigated the anti-inflammatory action of intravitreal lupeol in a rodent model of panuveitis induced by Mycobacterium bovis Calmette-Guérin Bacillus (BCG). Rats were submitted to electroretinography and clinical analyses on days 3, 7, and 15 after uveitis induction. In addition, histopathological analysis, and indirect quantification of myeloperoxidase (MPO) and N-acetylglucosaminidase (NAG) in the posterior segment were performed. Treatment with lupeol (100 µM) significantly decreased IL-6 and IL-8 levels in comparison to untreated LPS-activated ARPE-19 cells. This reduction was similar to that detected in ARPE-19 cells treated with dexamethasone. The results of the in vivo assay demonstrated that intravitreal lupeol is able to modulate inflammation in the anterior and posterior segment of the rat eyes, indicating that it should be further investigated as a novel potential candidate for management of uveitis.

Intravitreal injection of the synthetic peptide LyeTx I b, derived from a spider toxin, into the rabbit eye is safe and prevents neovascularization in a chorio-allantoic membrane model

Background

The great diversity of molecules found in spider venoms include amino acids, polyamines, proteins and peptides, among others. Some of these compounds can interact with different neuronal receptors and ion channels including those present in the ocular system. To study potential toxicity and safety of intravitreal injection in rabbits of LyeTx I b, a synthetic peptide derived from the toxin LyeTx I found in venom from the spider Lycosa eritrognatha and to evaluate the angiogenic activity on a CAM model.

Methods

ARPE-19 cells were treated with LyeTx I b (0.36; 0.54; 0.72; 2.89; 4.34 or 9.06 μM). In this study, New Zealand rabbits were used. LyeTx I b (2.89 μM) labeled with FITC dissolved in PBS, or only PBS, were injected into vitreous humor. Electroretinogram (ERG) was recorded 1 day before injection and at 7, 14 and 28 days post-injection. Clinical examination of the retina was conducted through tonometer and eye fundus after ERG. Eyes were enucleated and retinas were prepared for histology in order to assess retinal structure. CAMs were exposed to LyeTx I b (0.54; 0.72; 2.17 or 2.89 μM).

Results

ARPE-19 cells exposed to LyeTx I b showed cell viability at the same levels of the control. The fluorescence of LyeTx I b labeled with FITC indicated its retinal localization. Our findings indicate ERG responses from rats injected in the eye with LyeTx I b were very similar to the corresponding responses of those animals injected only with vehicle. Clinical examination found no alterations of intraocular pressure or retinal integrity. No histological damage in retinal layers was observed. CAM presented reduced neovascularization when exposed to LyeTx I b.

Conclusions

Intravitreal injection of LyeTx I b is safe for use in the rabbit eye and prevents neovascularization in the CAM model, at Bevacizumab levels. These findings support intravitreal LyeTx I b as a good candidate to develop future alternative treatment for the retina in neovascularization diseases.

Retinal Gene Therapy: Surgical Vector Delivery in the Translation to Clinical Trials

An exceptionally high number of monogenic disorders lead to incurable blindness, making them targets for the development of gene-therapy. In order to successfully apply therapeutic vector systems in vivo, the heterogeneity of the disease phenotype needs to be considered. This necessitates tailored approaches such as subretinal or intravitreal injections with the aim to maximize transduction of target cell populations, while minimizing off-target effects and surgical complications. Strategic decisions on parameters of the application are crucial to obtain the best treatment outcomes and patient safety. While most of the current retinal gene therapy trials utilize a subretinal approach, a deeper understanding of the numerous factors and considerations in choosing one delivery approach over the other for various ocular pathologies could lead to an improved safety and treatment efficacy. In this review we survey different vector injection techniques and parameters applied in recent retinal (pre-)clinical trials. We explore the advantages and shortcomings of each delivery strategy in the setting of different underlying ocular pathologies and other relevant factors. We highlight the potential benefits for patient safety and efficacy in applying those considerations in the decision making process.