Somatostatin for Uveitic Cystoid Macular Edema (CME)

Effect of somatostatin on human retinal pigment epithelial cells permeability

PURPOSE

To assess the effect of somatostatin (SST) on the permeability of human retinal pigment epithelial cells.

METHODS

We conducted two experiments, exposing cells from human-fetal retinal pigment epithelium (hfRPE) cultures to vascular endothelial growth factor (VEGF), with or without SST pretreatment, in one, and to hypoxic conditions, again with or without SST pretreatment, in the other. The paracellular permeability of hfRPE was assessed by measuring transepithelial electrical resistance (TER) and fluorescein isothiocyanate-sodium (FITC-sodium) flux. Immunochemistry analysis was used to assess the expression of occludin and Zonula occludens-1(ZO-1).

RESULTS

Both VEGF and hypoxia increased permeability of the hfRPE, as measured by TER and tracer flux, and decreased occludin and ZO-1staining, as measured by immunochemistry. Pretreatment of cultures with SST partially counteracted these effects.

CONCLUSIONS

Somatostatin may play a role in the regulation of permeability across retinal pigment epithelium. It may act as an anti-permeability factor in the retina through the enhancement of tight junction function.

Neuropeptide receptors as potential drug targets in the treatment of inflammatory conditions

Cross-talk between the nervous, endocrine and immune systems exists via regulator molecules, such as neuropeptides, hormones and cytokines. A number of neuropeptides have been implicated in the genesis of inflammation, such as tachykinins and calcitonin gene-related peptide. Development of their receptor antagonists could be a promising approach to anti-inflammatory pharmacotherapy. Anti-inflammatory neuropeptides, such as vasoactive intestinal peptide, pituitary adenylate cyclase-activating polypeptide, α-melanocyte-stimulating hormone, urocortin, adrenomedullin, somatostatin, cortistatin, ghrelin, galanin and opioid peptides, are also released and act on their own receptors on the neurons as well as on different inflammatory and immune cells. The aim of the present review is to summarize the most prominent data of preclinical animal studies concerning the main pharmacological effects of ligands acting on the neuropeptide receptors. Promising therapeutic impacts of these compounds as potential candidates for the development of novel types of anti-inflammatory drugs are also discussed.

Review of Intermediate Uveitis

The purpose of this article is to highlight evidence about the medical and surgical management of intermediate uveitis (IU). Updated understandings of the immunopathology of IU were reviewed in this retrospective literature review. Literature selection for this review was based on the PubMed database (National Library of Medicine) and OVID database (Wolters Kluwer). Articles deemed relevant were selected and highlighted. Intermediate uveitis is most often a benign form of uveitis. Since intermediate uveitis has been described in association with different systemic disorders, the initial diagnostic evaluation should serve to exclude masquerade syndromes and infectious diseases in which immunosuppression may be ineffective or contraindicated. Although the pathogenesis of intermediate uveitis is not fully understood, identification of proinflammatory molecules involved in the IU has contributed to the development and implementation of new therapies. Studies about the use of various immunosuppressants, biological agents and surgical treatment on IU have provided more evidence for managing IU. Nevertheless, corticosteroids remain the mainstay of treatment. The treatment options of intermediate uveitis are evolving, with the development of various immunosuppressants and biological agents. The management of intermediate uveitis should be tailored individually, based on specific causes of the disease and associated complications.

Interventions for the treatment of uveitic macular edema: a systematic review and meta-analysis

Background

Uveitic macular edema is the major cause of reduced vision in eyes with uveitis.

Objectives

To assess the effectiveness of interventions in the treatment of uveitic macular edema.

Search strategy

Cochrane Central Register of Controlled Trials, Medline, and Embase. There were no language or data restrictions in the search for trials. The databases were last searched on December 1, 2011. Reference lists of included trials were searched. Archives of Ophthalmology, Ophthalmology, Retina, the British Journal of Ophthalmology, and the New England Journal of Medicine were searched for clinical trials and reviews.

Selection criteria

Participants of any age and sex with any type of uveitic macular edema were included. Early, chronic, refractory, or secondary uveitic macular edema were included. We included trials that compared any interventions of any dose and duration, including comparison with another treatment, sham treatment, or no treatment.

Data collection and analysis

Best-corrected visual acuity and central macular thickness were the primary outcome measures. Secondary outcome data including adverse effects were collected.

Conclusion

More results from randomized controlled trials with long follow-up periods are needed for interventions for uveitic macular edema to assist in determining the overall long-term benefit of different treatments. The only intervention with sufficiently robust randomized controlled trials for a meta-analysis was acetazolamide, which was shown to be ineffective in improving vision in eyes with uveitic macular edema, and is clinically now rarely used. Interventions showing promise in this disease include dexamethasone implants, immunomodulatory drugs and anti-vascular endothelial growth-factor agents. When macular edema has become refractory after multiple interventions, pars plana vitrectomy could be considered. The disease pathophysiology is uncertain and the course of disease unpredictable. As there are no clear guidelines from the literature, interventions should be tailored to the individual patient.

Vitreous levels of somatostatin in patients with chronic uveitic macular oedema

PURPOSE

Intravitreal somatostatin (SST) levels are decreased in patients with diabetic macular oedema. This deficit may be involved in the pathogenesis of this condition. The aim of the present study was to determine SST concentration in the vitreous fluid of patients with chronic uveitic macular oedema (CUMO) and quiescent intraocular inflammation.

METHODS

Plasma and vitreous fluid samples were obtained during vitrectomy from 11 eyes of patients with CUMO and from 42 eyes of control subjects (idiopathic epiretinal membrane, macular hole). SST concentration was measured by radioimmunoassay.

STATISTICS

χ(2)-square test, Mann-Whitney U-test, Wilcoxon test, Spearman's rank correlation coefficient, and multivariant linear regression models.

RESULTS

Plasma SST concentrations were similar in uveitic patients and controls (28.25 pg/ml (21.3-31) vs 28.7 pg/ml (22-29.5); P=0.869). A higher vitreous concentration of proteins was found in uveitic patients (1.59±0.38 mg/ml vs 0.73±0.32 mg/ml, P<0.0001). Vitreous SST was markedly lower in uveitic patients, both in absolute terms and after adjusting for total intravitreous protein concentration (39.37 pg/ml (6.16-172) vs 486.73 pg/ml (4.7-1833), P<0.0001; 33.1 pg/mg (3.9-215.74) vs 629.75 pg/mg (6.91-2024), P<0.0001). No correlations were found between plasma and vitreous concentration of SST in either group (ρ=0.191, P=0.57 and ρ=0.49, P=0.66). There were no correlations between vitreous SST concentration and visual acuity or macular thickness in uveitic patients (ρ=0.302, P=0.31 and ρ=0.45, P=0.13).

CONCLUSIONS

Intravitreous SST is decreased in patients with CUMO and quiescent intraocular inflammation. The deficit of SST may have a role in the pathogenesis of this condition.

Treatment of macular edema because of occlusive vasculitis with bevacizumab (avastin): efficacy of three consecutive monthly injections

PURPOSE

To report the efficacy of intravitreal bevacizumab, administered in a series of three monthly injections followed by a period of observation, in the treatment of cystoid macular edema because of occlusive vasculitis.

METHODS

This is a retrospective review of 13 consecutive eyes of 13 patients with cystoid macular edema because of occlusive vasculitis, which had been unresponsive to other medications and were treated with intravitreal bevacizumab (1.25 mg). The evaluation consisted of a complete ophthalmologic examination, including best-corrected visual acuity measurement, ophthalmoscopy, fluorescein angiography, and optical coherence tomography. The eyes received a series of 3 monthly injections followed by a 3-month observation period.

RESULTS

A significant improvement in foveal thickness and visual acuity was obtained after the first injection, which increased after the second and the third injections and was maintained for 1.5 months after the last injection. The 2 parameters returned to the baseline values 3 months after the last treatment. There were no ocular or systemic adverse effects.

CONCLUSION

Intravitreal injection of bevacizumab seems to be well tolerated and is associated with short-term improvement of visual acuity and decreased retinal thickness in patients with cystoid macular edema because of vasculitis that is resistant to conventional therapy.

Periocular triamcinolone acetonide injections for cystoid macular edema complicating noninfectious uveitis

PURPOSE

To describe the effectiveness of periocular corticosteroid injections in the treatment of cystoid macular edema (CME) complicating noninfectious uveitis.

DESIGN

Retrospective cohort study.

METHODS

A total of 126 patients (156 eyes) were evaluated for presence of CME, visual acuity, intraocular pressure, degree of intraocular inflammation, and the presence of ocular complications. Main outcome measures included resolution of CME and visual acuity at the 1- and 3-month visits, failure of periocular injection therapy, and side effects.

RESULTS

Twenty-eight percent of the 156 eyes had anterior uveitis, 22% intermediate uveitis, and 31% panuveitis. Of these eyes, 53% demonstrated clinical resolution of CME at 1 month and 57% at 3 months after a single periocular corticosteroid injection. Forty eyes were treated with >1 periocular injection because the CME persisted 1 month after the first injection (1 additional injection in 21 eyes; 2 additional injections in 14 eyes; >2 additional injections in 5 eyes). For the 21 eyes treated with a second periocular corticosteroid injection, 81% had no CME 1 month after the second injection and 48% had no CME 3 months after the second injection. Twenty-three eyes (15%) failed periocular corticosteroid therapy. Of eyes initially responding to periocular injection, CME recurred in 53% (median time to recurrence = 20.2 weeks). A halving of the visual angle was observed in 52% and 57% at the 1- and 3-month visits after injection, respectively.

CONCLUSIONS

Fifty-three percent of eyes treated with a single periocular corticosteroid injection had clinical resolution of CME 1 month after the injection.

Bevacizumab in inflammatory eye disease

PURPOSE

To report the effect of intravitreal bevacizumab (Avastin; Genentech Inc, South San Francisco, California, USA) on visual acuity and macular thickness in patients with inflammatory choroidal neovascularization (CNV) or cystoid macular edema (CME).

DESIGN

Retrospective, noncomparative, interventional case series.

METHODS

Each eye received 1.25 mg of intravitreal bevacizumab at baseline. Follow-up examinations were scheduled at 1- to 2-month intervals, with additional injections at the discretion of the physician. Comprehensive evaluations, including Snellen best-corrected visual acuity (BVCA) and optical coherence tomography measurements, were performed at each visit. Main outcome measures were BCVA and central subfield thickness (CST), as measured by optical coherence tomography.

RESULTS

Thirty-four eyes of 30 patients with inflammatory CNV (n = 21 eyes of 19 patients; 9 male, 10 female) or CME (n = 13 eyes of 11 patients; 4 male, 7 female) were identified. Median ages were 52 years (range, 7 to 83) and 67 years (range, 17 to 83) for the CNV and CME groups, respectively. The median length of follow-up for CNV eyes was 7 months (range, 1 to 28) while the median follow-up for CME eyes was 13 months (range, 1 to 20). Both groups received a median of two injections (range, 1 to 9 for CNV and 1 to 4 for CME). For eyes with CNV, BCVA improved significantly at follow-up month 1, but was not different from baseline thereafter; CST remained unchanged throughout follow-up. For eyes with CME, neither BCVA nor CST changed significantly over the course of follow-up.

CONCLUSIONS

Bevacizumab appears to stabilize BCVA and CST for eyes with inflammatory CNV or CME.

Ranibizumab for refractory uveitis-related macular edema

PURPOSE

To evaluate the effect of intravitreal ranibizumab injections (Lucentis; Genentech Inc, South San Francisco, California, USA) on refractory cystoid macular edema (CME) in patients with controlled uveitis who have failed oral and regional corticosteroid treatment, the mainstays of current medical therapy.

DESIGN

Prospective, noncomparative, interventional case series.

METHODS

Seven consecutive patients with controlled uveitis and refractory CME who had failed corticosteroid treatment were studied. One eligible patient chose not to participate and another did not complete follow-up for nonmedical reasons. Intravitreal ranibizumab injections (0.5 mg) were given monthly for 3 months, followed by reinjection as needed. The primary outcome was the mean change in best spectacle-corrected visual acuity (VA) from baseline to 3 months, and the secondary objective was the mean change in central retinal thickness (CRT) on ocular coherence tomography. Six-month outcomes were also assessed.

RESULTS

At 3 months, the mean increase in acuity for the 6 patients who completed follow-up was 13 letters (2.5 lines), and the mean decrease in CRT was 357 mum. Both VA and CRT improved significantly between baseline and 3 months (P = .03 for each). Although most patients required reinjection, this benefit was maintained at 6 months. There were no significant ocular or systemic adverse effects.

CONCLUSIONS

Intravitreal ranibizumab led to an increase in VA and regression of uveitis-associated CME in patients refractory to or intolerant of standard corticosteroid therapy. Further studies of this promising treatment are warranted.

Activation of somatostatin receptor (sst 5) protects the rat retina from AMPA-induced neurotoxicity

In a recent study, we employed an in vivo model of retinal excitotoxicity to investigate the neuroprotective effect of somatostatinergic agents. Intravitreal administration of somatostatin and sst(2) selective agonists protected the retina from (RS)-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid hydrobromide (AMPA) induced excitotoxicity. The sst(1) and sst(4) selective ligands had no effect (Kiagiadaki and Thermos, 2008). The presence of sst(5) receptors in rat retina was only recently reported (Ke and Zhong, 2007). Synthetic agonists that activate sst(2) receptors also bind with high affinity to the sst(5) subtype. In the present study the putative neuroprotective effects of sst(5) receptor activation were investigated. Adult female and male Sprague-Dawley (250-350g) rats were employed. Groups of animals received intravitreally PBS (50mM) or AMPA (42 nmol/eye) alone or in combination with L-817,818 (sst(5), 10(-5), 10(-4)M). To exclude neuroprotective effects via the activation of sst(2) receptors, L-817,818 (10(-4)M) was coinjected with the sst(2) antagonist CYN-154806 (10(-4)M). Immunohistochemistry (IHC) studies using the anti-retinal marker choline acetyltransferase (ChAT) and TUNEL staining were employed to examine retinal cell loss and protection. IHC and Western blot analysis were also employed to assess whether the sst(5) receptors are viable in the AMPA treated tissue as compared to control retina. sst(5) receptors were not affected by AMPA. L-817,818 protected the retina from the AMPA insult in the dose of 10(-4)M, while CYN-154806 (10(-4)M) had no effect on the sst(5) neuroprotection. TUNEL staining confirmed the AMPA-induced retinal toxicity and the L-817,818 neuroprotection. These results demonstrate for the first time that sst(5) receptors are functional in the retina, and that sst(5) analogs administered intravitreally protect the retina from excitotoxicity. Further studies are essential to ascertain the therapeutic relevance of these results.

Traitement médical de l’œdème maculaire

Macular edema was first described more than a century ago, and its medical treatment has made great progress thanks to recent pharmacological advances. Administration is topical, local (peri- or intraocular), or systemic. Nonsteroidal anti-inflammatory agents and corticosteroids are the mainstay therapy when inflammation is involved, as well as acetazolamide in many cases. More recently, molecules such as protein kinase-C- beta inhibitors and anti-VEGF agents are already or will soon be available, to add to our therapeutic armamentarium. Perhaps combination therapy will become popular, as is the case with age-related macular degeneration.

Intravitreal bevacizumab for treatment of uveitic macular edema

PURPOSE

To evaluate the short-term safety and efficacy of intravitreal bevacizumab for the treatment of cystoid macular edema (CME) secondary to uveitis.

DESIGN

Retrospective, noncomparative, interventional case series.

PARTICIPANTS

Thirteen patients undergoing treatment for recalcitrant uveitic macular edema at one referral center.

METHODS

Charts of patients who received one 2.5-mg intravitreal injection of bevacizumab in one eye were reviewed for clinical information including best-corrected Snellen visual acuity (VA), examination findings, optical coherence tomography (OCT) results, and fluorescein angiography results. Kaplan-Meier survival analysis was used to calculate probability success rates. The statistical significance of change in mean retinal thickness and VA was assessed using repeated-measures analysis of variance.

MAIN OUTCOME MEASURES

Assessments of changes in best-corrected Snellen VA and OCT retinal thickness were made.

RESULTS

Six (46.15%) patients had a decrease in foveal thickness at the end of the follow-up, whereas 5 (38.4%) patients had an improvement of VA by > or =2 lines 84 days or more after the injection. Mean retinal thickness showed a significant decrease over the follow-up (P<0.02). The change in mean logarithm of the minimum angle of resolution VA over the follow-up was not significant (P>0.05). Survival analysis showed that the probability of any improvement in VA increased progressively starting at 6 weeks and reached 81% at 14 weeks. No significant ocular or systemic adverse effects were observed.

CONCLUSIONS

These results suggest that a single intravitreal injection of bevacizumab is well tolerated and is associated with short-term improvement in VA and decreased OCT retinal thickness in a considerable proportion of patients with uveitic CME resistant to conventional therapy. Further evaluation of intravitreal bevacizumab for uveitic CME in controlled randomized studies is warranted.

Uveitis: Advances in understanding of pathogenesis and treatment

Uveitis is a leading cause of blindness affecting individuals of all ages, genders, and races. Uveitis may be due to autoimmune, infectious, toxic, malignant, or traumatic processes. Some evidence supports an association between conditions previously presumed to be autoimmune and viral infectious agents. For autoimmune uveitis, therapy is nonspecific, typically beginning with corticosteroids. For nonresponsive disease or for corticosteroid sparing, recent reports on mycophenolate mofetil, infliximab, and interferon therapy show success for various forms of uveitis. Treatment of the complications of uveitis, especially cystoid macular edema, is difficult. Vitamin E appears to offer little benefit, whereas octreotide may be effective. Recent collaborative efforts at standardization in the field should enhance studies on these conditions.