In vitro effects of dexamethasone on hypoxia-induced hyperpermeability and expression of vascular endothelial growth factor

Intravitreal triamcinolone for intraocular inflammation and associated macular edema

Triamcinolone acetonide (TA) is a corticosteroid that has many uses in the treatment of ocular diseases because of its potent anti-inflammatory and anti-permeability actions. Intraocular inflammation broadly referred to as uveitis can result from several causes, including the immune system and after ophthalmic surgery. One of the most common reasons for vision loss with uveitis is macular edema. TA has been used for many years as an intravitreal injection for the treatment of ocular diseases. Several case control studies have been reported showing the efficacy of TA in the treatment of intraocular inflammation and associated macular edema caused by Behcet's disease, Vogt-Koyanagi-Harada syndrome, sympathetic ophthalmia and white dot syndromes. It has also been shown efficacious in cases of pars planitis and idiopathic posterior uveitis. Some authors have reported its use in postoperative cystoid macular edema. Many of the studies on the use of TA in controlling intraocular inflammation and concomitant macular edema showed its effect to be transient in many patients requiring reinjection. Complications can arise from intravitreal injection of TA including elevated intraocular pressure and cataract. Rarely, it can be associated with infectious and non-infectious endophthalmitis. TA may be useful as an adjuvant in the treatment of uveitis and its associated macular edema, especially in patients resistant or intolerant to standard treatment.

Dexamethasone induces neurodegeneration but also up-regulates vascular endothelial growth factor A in neonatal rat brains

The use of dexamethasone (Dex) in premature infants to prevent and/or treat bronchopulmonary dysplasia can adversely affect early neurodevelopment and probably result in loss of cerebral volume. Vascular endothelial growth factor A (VEGF), specifically VEGF(164) isoform has neurotrophic, neuroprotective and neurogenesis enhancing effects. Previous studies have demonstrated that Dex usually down-regulates VEGF. In the present study we investigated the effect of Dex on brain growth and VEGF in the neonatal rat brain. The pups in each litter were divided into the vehicle (n=84) or Dex-treated (n=98) groups. Rat pups in the Dex group received one of three different regimens of i.p. Dex which included tapering doses on postnatal days 3-6 (0.5, 0.25, 0.125 and 0.06 mg/kg, respectively), or repeated doses of 0.5 or 1 mg/kg/day on postnatal days 4-6 or single dose of 0.031, 0.06, 0.125, 0.25 or 0.5 mg/kg on postnatal day 6. The total VEGF protein and mRNA expression of the three main VEGF splice variants (VEGF(120), VEGF(164), and VEGF(188)) were measured in the rat pup brain using enzyme-linked immunosorbent assay and real-time reverse transcription polymerase chain reaction, respectively. Treatment with Dex significantly decreased the gain of body and brain weight. The tapering and repeated doses of Dex significantly increased caspase-3 activity, VEGF protein and the expression of mRNA of VEGF(164) and VEGF(188) splice variants but the single dose did not. We conclude that Dex is neurodegenerative in the developing brain but also increases VEGF which may play a neurotrophic and neuroprotective role.

Dexamethasone inhibits leukocyte accumulation and vascular permeability in retina of streptozotocin-induced diabetic rats via reducing vascular endothelial growth factor and intercellular adhesion molecule-1 expression

Intravitreal injection of corticosteroid has been used to treat diabetic macular edema, however, the exact mechanism remains unknown. In the present experiment, four weeks after streptozotocin administration, intravitreal injection of dexamethasone (50 microg/10 microl) was performed. After 2 d injection, we investigated the effect of dexamethasone on leukocyte accumulation, vascular permeability and the expression of vascular endothelial growth factor (VEGF) and intercellular adhesion molecule-1 (ICAM-1) in streptozotocin-diabetic rats. Accumulated leukocytes were counted in vivo by acridine orange leukocyte fluorography, the retinal vascular permeability was measured by the Evans blue assay. The mRNA and protein level of VEGF and ICAM-1 were analyzed with real-time quantitative polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) respectively. Dexamethasone downregulated VEGF and ICAM-1 expression in diabetic rats which correlated with its effect on leukocytes accumulation and retinal vascular permeability. The present data revealed that dexamethasone may inhibit retinal accumulation and leukostasis accumulation and vascular permeability through its blockage on VEGF and ICAM-1 expression.

Intravitreal triamcinolone acetonide for patients with macular oedema due to central retinal vein occlusion in Taiwan

PURPOSE

To evaluate the safety and outcome of intravitreal triamcinolone acetonide as treatment for macular oedema secondary to central retinal vein occlusion (CRVO) in Taiwanese.

METHODS

The prospective clinical interventional study included 43 patients (43 eyes) with macular oedema due to CRVO. The study group consisted of 22 patients who had accepted an intravitreal injection of 4 mg of triamcinolone acetonide. The control group included 21 patients without intravitreal triamcinolone acetonide. Examination included assessment of best-corrected visual acuity, slit-lamp biomicroscopy, measurement of intraocular pressure, ophthalmoscopy, and optical coherence tomography (OCT).

RESULTS

The mean follow-up was 283.00+/-70.62 days in the study group and 354.05+/-173.18 days in the control group, respectively. In the study group, visual acuity measurements improved significantly (P=0.007) from 1.00+/-0.45 logMAR preoperatively to a best postoperative visual acuity of 0.67+/-0.65 logMAR. Seventeen eyes (77.3%) gained improvement in visual acuity with 12 eyes (54.5%) showing an increase in visual acuity of at least two Snellen lines. All 22 patients showed significant macular oedema resolution in OCT examination (P<0.001) from 594.36+/-177.78 mum preoperatively to a mean retinal thickness of 317.23+/-196.83 mum postoperatively postintravitreal injection. In the control group, baseline best-corrected visual acuity and best-corrected visual acuity during the follow-up did not vary significantly (P=0.457).

CONCLUSION

Intravitreal triamcinolone acetonide can lead to a significant improvement in visual acuity and a resolution of macular oedema in patients with CRVO.

Dexamethasone coordinately regulates angiopoietin-1 and VEGF: a mechanism of glucocorticoid-induced stabilization of blood-brain barrier

Glucocorticoids stabilize the blood-brain barrier (BBB), leading to attenuation of vasogenic brain edema. However, the action mechanism of glucocorticoids has been poorly elucidated. To elucidate the mechanism, we investigated whether dexamethasone (Dex), a synthetic glucocorticoid hormone, regulates the levels of key permeability regulating factors such as angiopoietin-1, angiopoietin-2, and vascular endothelial growth factor (VEGF) in the three types of cells comprising BBB. Dex increased the level of angiopoietin-1 mRNA and protein and decreased VEGF mRNA and protein in brain astrocytes and pericytes, but not in endothelial cells. The mRNA and protein of angiopoietin-2 were detected only in endothelial cells and not regulated by Dex. The Dex-induced regulation of angiopoietin-1 and VEGF was inhibited by RU486, suggestive of glucocorticoid receptor mediation. The mRNA stability of angiopoietin-1 and VEGF was not changed by Dex treatment, implying that Dex increases angiopoietin-1 and decreases VEGF through transcriptional regulation. This is the first study showing the coordinate regulation of angiopoietin-1 and VEGF by glucocorticoids, suggesting a novel mechanism underlying glucocorticoids-induced stabilization of BBB.

Current treatment approaches in diabetic macular edema

PURPOSE

To review current treatment approaches in diabetic macular edema (DME).

METHODS

The underlying pathopathology, classifications and diagnostic examination techniques including fluorescein angiography, optical coherence tomography and stereoscopic biomicroscopy. Treatment modalities with focal or grid argon laser photocoagulation, pars plana vitrectomy with and without peeling of the inner limiting membrane (ILM), as well as intravitreal injections using triamcinolone acetonide or novel vascular endothelial growth factor (VEGF) inhibitors are described.

RESULTS

DME results from a series of biochemical and cellular changes, causing progressive leakage and exudation. Focal and grid photocoagulation remains the standard care for diabetic maculopathy. However, the availability of new agents raises the possibility of improvements if significant benefits can be validated in randomized clinical trials. Posterior vitreous attachments play a critical role through several mechanical or physiological mechanisms. Vitrectomy without ILM removal seems to be effective in reducing the retinal thickness and improving visual acuity.

CONCLUSION

A proper evaluation of the vitreous and retina is fundamental to select the most appropriate treatment approach in DME. While small microaneurysms with focal DME may be treated by conventional focal photocoagulation, diffuse DME which do not respond to grid photocoagulation may benefit from intravitreal injections using triamcinolone acetonide or novel VEGF inhibitors. Eyes with DME and additional vitreous traction may benefit from pars plana vitrectomy without ILM peeling. A combination of laser, pharmacological and surgical treatment modalities may be necessary to maintain central vision in eyes with DME.

Regulation of VEGF mRNA expression and protein secretion by TGF-beta2 in human retinal pigment epithelial cells

VEGF secretion by the human retinal pigment epithelium (hRPE) plays an important role in retinal and choroidal neovascularization. In this study, transforming growth factor-beta2 (TGF-beta2)-induced vascular endothelial growth factor (VEGF) gene expression was investigated in hRPE cells. Treatment of hRPE cells with TGF-beta2 for 24 and 48h as compared to 8h resulted in markedly increased VEGF secretion by fivefold and nine-fold, respectively. Induced VEGF mRNA peaked within 3h of stimulation and remained above the basal at 36h. Stimulation of VEGF expression by TGF-beta2 was blocked by cycloheximide, suggesting that de novo protein synthesis is required. Induced VEGF production was strongly inhibited by anti-inflammatory agents, dexamethasone and cyclosporin A. Despite of the weak stimulation of VEGF expression by TNF-alpha or bFGF alone, co-administration of either of these two cytokines synergized the effect of TGF-beta2 on VEGF mRNA expression and protein production. Quantitative RT-PCR revealed that the synergy was predominantly at the level of VEGF transcription. Moreover, TGF-beta2-induced RPE VEGF secretion was significantly reduced by inhibitors of mitogen-activated protein (MAP) kinase (MEK) (U0126), p38 (SB202190), c-Jun NH2-terminal kinase (JNK), Sp600125, protein tyrosine kinase (PTK) (Genistein), and phosphatidylinositol 3-kinase (PI3K) (Ly294002). Induced VEGF expression was completely abrogated by inhibitors of protein kinase C (PKC) (Ro318220), nuclear factor-kappaB (NF-kappaB) [caffeic acid phenethyl ester (CAPE)], and reactive oxygen species (ROS) [N-acetyl-cysteine (Nac) and diphenyleneiodonium (DPI)]. These results suggest that MEK, p38, JNK, PI3K, and NF-kappaB as well as multiple essential signaling intermediates, including PKC, PTK and ROS, are involved in hRPE VEGF up regulation by TGF-beta2.

Verteporfin photodynamic therapy and anti-angiogenic drugs: potential for combination therapy in exudative age-related macular degeneration

OBJECTIVE

To discuss the rationale for combining anti-angiogenic treatment with verteporfin (Visudyne) photodynamic therapy in the management of choroidal neovascularization (CNV) due to age-related macular degeneration (AMD) and evaluate available evidence for the therapeutic benefits of such approaches.

SCOPE

The Medline and EMBASE databases were searched in October 2006 to retrieve relevant articles. Additional articles were obtained from the reference lists of retrieved articles, as well as from recent scientific meetings and company websites.

FINDINGS

Treatments for CNV due to AMD can be directed at either the vascular component of CNV (the new vessels that proliferate and leak blood and fluid) or the angiogenic component that leads to the development of the condition. Verteporfin targets the vascular component, whereas anti-angiogenic agents (such as pegaptanib and ranibizumab) target key mediators of the angiogenic cascade. The different mechanisms of action of these approaches offer the potential for additive or synergistic effects with combination therapy. In addition, anti-angiogenic agents might counteract upregulation of angiogenic factors (including VEGF) that occur after verteporfin photodynamic therapy. Results from preclinical and clinical studies of the combination of ranibizumab or pegaptanib with verteporfin warrant continued investigation.

CONCLUSIONS

The use of anti-angiogenic agents in combination with verteporfin may have the potential to improve visual outcomes and reduce the number of treatments in eyes with CNV due to AMD, and requires further evaluation in randomized, controlled clinical trials.

Intravitreal triamcinolone as an adjunct in the treatment of concomitant proliferative diabetic retinopathy and diffuse diabetic macular oedema

PURPOSE

To investigate if triamcinolone acetonide (TA) can be an adjunct to laser treatment in patients with concomitant non-high-risk proliferative diabetic retinopathy (PDR) and diffuse clinically significant diabetic macular oedema (CSMO).

METHODS

This prospective, interventional and comparative clinical study included 32 eyes of 16 patients with bilateral concomitant non-high-risk PDR and diffuse CSMO. Each patient received 4 mg intravitreal TA for the eye with worse visual acuity (study group) and macular focal and grid laser photocoagulation (MP) for the other eye (control group). One month later, each patient received four sessions of panretinal photocoagulation for both eyes plus MP for the eyes in the study group. The visual and angiographic results of both groups were compared.

RESULTS

In the study group, the mean visual acuity (VA) improved from 0.12 +/- 2.3 lines at the baseline to 0.19 +/- 3.1 (P = 0.004), 0.20 +/- 3.2 (P = 0.004), 0.19 +/- 3.6 (P = 0.009) and 0.19 +/- 3.3 lines (P = 0.091) at the 1-, 3-, 6- and 9-month follow-up intervals, respectively. The macular oedema was found to be resolved in 11 eyes (69%) and decreased in five eyes (31%). In the control group, the mean VA deteriorated progressively from 0.41 +/- 3.1 lines at the baseline to 0.20 +/- 3.1 lines (P = 0.026) at the end of the study and the macular oedema decreased only in three eyes (19%) at the sixth follow-up month.

CONCLUSIONS

During the follow-up period of the study, intravitreal TA as an adjunct in the treatment of concomitant non-high-risk PDR and diffuse CSMO led to a more-favourable clinical outcome than conventional laser treatment.

Intravitreal triamcinolone acetonide for diffuse diabetic macular oedema: 6-month results of a prospective controlled trial

PURPOSE

To evaluate prospectively the efficacy and safety of one intravitreal injection of 4 mg triamcinolone acetonide for refractory diffuse diabetic macular edema.

METHODS

Seventeen patients with bilateral diabetic macular edema unresponsive to laser photocoagulation. In all patients, one eye was injected, and the other served as a control. The intervention consisted in intravitreal injection of 4 mg triamcinolone acetonide. The main outcome measure was central macular thickness (CMT) at 4, 12 and 24 weeks, measured by Optical Coherence Tomography. Secondary outcomes were Early Treatment Diabetic Rentinopathy Study (ETDRS) scores, intraocular pressure and cataract PROGRESSION.

RESULTS

Before injection, mean +/- SD CMT was 566.4 +/- 182.4 mum in injected eyes. Four, 12, and 24 weeks after injection, it was 228.4 +/- 47.5 mum, 210.9 +/- 87.2 mum and 358.5 +/- 160.5 mum respectively. CMT was significantly lower in injected eyes vs. control eyes except 24 weeks after injection because of a recurrence of macular edema in 9/17 injected eyes. Mean +/- SD gain in ETDRS score was significantly better in injected eyes vs. control eyes 4, 12 and 24 weeks after TA injection. In 9 of the 17 injected eyes, intraocular pressure exceeded 24 mmHg and was controlled by topical medication.

CONCLUSION

In the short-term, intravitreal injection of triamcinolone effectively reduces macular thickening due to diffuse diabetic macular edema and improves visual acuity in most cases. The long-term effect of this treatment and predictive factors of visual recovery remain to be elucidated.

Intravitreal triamcinolone acetonide for patients with macular edema due to branch retinal vein occlusion

We designed a case series study to evaluate the outcome of intravitreal triamcinolone acetonide for the treatment of macular edema due to branch retinal vein occlusion (BRVO). The prospective comparative nonrandomized clinical interventional study included 27 patients (27 eyes) with macular edema due to BRVO. The study group consisted of 16 patients who had accepted an intravitreal injection (IVI) of 4 mg triamcinolone acetonide. The control group included 11 patients without IVI of triamcinolone acetonide. The mean follow-up was 103.00 +/- 36.24 days in the study group and 94.55 +/- 36.31 days in the control group. In the study group, visual acuity measurements improved significantly (p < 0.001) from 0.77 +/- 0.43 logarithm of minimal angle of resolution (logMAR) preoperatively to a best postoperative visual acuity of 0.44 +/- 0.43 logMAR. Fourteen eyes (87.5%) gained improvement in visual acuity, with 10 eyes (62.5%) showing an increase in visual acuity of at least two Snellen lines. All 16 patients showed significant macular edema resolution in optical coherence tomography examination (p < 0.001) and perivascular leakage decrease in fluorescein angiography post-IVI. In the control group, baseline best-corrected visual acuity and best-corrected visual acuity during the follow-up did not vary significantly (p = 0.294). In conclusion, IVI of triamcinolone acetonide can lead to an increase in visual acuity and a resolution of macular edema in patients with BRVO.

Panretinal photocoagulation and intravitreal triamcinolone acetonide for the management of proliferative diabetic retinopathy with macular edema

PURPOSE

To investigate intravitreal triamcinolone acetonide (IVTA) as an adjunctive therapy to panretinal photocoagulation (PRP) in patients with both high-risk proliferative diabetic retinopathy (PDR) and clinically significant macular edema (CSME).

METHODS

Thirty-five eyes diagnosed with both high-risk PDR and CSME underwent PRP and a single injection of 4 mg of IVTA (IVTA group). Visual, anatomic, and fluorescein angiographic changes were documented. Any complications resulting from the combined procedure were noted. These data were compared retrospectively to 35 eyes that underwent grid laser treatment to the macula followed 2 weeks later by PRP (laser group). Main outcome measures included change in best-corrected visual acuity, improvement in macular edema (clinical or angiographic), and control of the neovascular disease.

RESULTS

Mean follow-up was 9.6 months for the IVTA group and 11.9 months for the laser group. Mean pretreatment best-corrected visual acuity was 20/286 in the IVTA group and 20/282 in the laser group (P = 0.80). After 9 months of follow-up, visual acuity was 20/80 in the IVTA group versus 20/156 in the laser group (P = 0.007). Thirty-four percent of eyes in the IVTA group had final vision of 20/40 or better versus 11% in the laser group (P = 0.044). At 9 months follow-up, 84% of IVTA eyes had complete resolution of macular edema versus 46% of laser eyes (P = 0.002). Three eyes in the IVTA group had recurrence of macular edema after 6 months and required reinjection of IVTA. Elevation in intraocular pressure occurred in eight eyes in the IVTA group and responded to topical therapy. Cataract progression was observed in nine eyes in the IVTA group.

CONCLUSIONS

The addition of intravitreal triamcinolone acetonide to PRP in the management of patients with both PDR and CSME seems promising. Further study is needed to assess the effect of this combined treatment.

Trans-Tenon's retrobulbar injection of triamcinolone acetonide for diffuse diabetic macular edema

PURPOSE

To determine whether a trans-Tenon's retrobulbar injection of triamcinolone acetonide (TA) is a safe and effective treatment for diffuse diabetic macular edema.

METHODS

Thirty-nine eyes of 30 diabetic patients with persistent macular edema were treated with 20 mg of TA injection. Central macular thickness (CMT) determined by optical coherence tomography (OCT) and visual acuity were evaluated before the injection and at 1, 2, 3, and 6 months, and up to 1 year in some eyes, after the injection.

RESULTS

The CMT decreased significantly from 478 +/- 129 microm (mean +/- SD) before injection to 316 +/- 102 microm at 1 month, 307 +/- 104 microm at 2 months, and 275 +/- 89 microm at 3 months after a single injection of TA. A 20% reduction of CMT from the initial value was maintained by a single injection of TA in 27 of 39 eyes (69.2%) at 3 months, in 14 of 22 eyes (63.6%) at 6 months, and in 5 of 7 eyes at 12 months. A recurrence of macular edema was observed in 10% of the eyes at 3 months, and in 22.7% at 6 months. The 17 eyes in which vitrectomy had been carried out had a more significant improvement in CMT than the eyes without vitrectomy.

CONCLUSION

A 20-mg trans-Tenon's retrobulbar TA injection is a safe and effective treatment for diabetic macular edema.

Inhibition of vascular endothelial growth factor by macrolides in cultured fibroblasts from nasal polyps

OBJECTIVE

In order to study a new mechanism of efficacy of 14-membered ring macrolides in treating chronic rhinosinusitis, inhibitory effects of macrolides on vascular endothelial growth factor production were examined in vitro.

METHODS

Vascular endothelisal growth factor production in cultured fibloblasts from human nasal polyps obtained from surgery for chronic paranasal sinusitis stimulated by hypoxia or tumor necrosis factor-alpha was assessed under the administration of Clarithromycin or Roxisthromycin by enzyme linked immunosorbent assay and reverse transcriptase polymerase chain-reaction.

RESULTS

Dose-dependent inhibitory effects on vascular endothelisal growth factor production stimulated by hypoxia or tumor necrosis factor-alpha were noted in the groups treated with Clarithromycin and Roxisthromycin, including inhibition of vascular endothelisal growth factor mRNA levels.

CONCLUSION

While, to date, several evidences have indicated that the mechanisms by which 14-membered ring macrolides reduce inflammation are not simply bactericidal, these results suggest another new mechanism of efficacy of macrolides in treating chronic rhinosinusitis.

Intravitreal triamcinolone injection for chronic diffuse diabetic macular oedema

PURPOSE

To determine the efficacy and safety of intravitreal triamcinolone in chronic diffuse diabetic macular oedema.

METHODS

This prospective, interventional consecutive case series study consisted of 59 eyes (36 patients) with chronic diffuse diabetic macular oedema, which received an intravitreal injection of 4 mg triamcinolone acetonide. The results were evaluated by clinical examination and fluorescein angiography. Potential complications such as a rise in intraocular pressure, cataract progression and endophthalmitis were recorded.

RESULTS

All patients completed at least 6 months follow up. The mean visual acuity improved significantly from 0.17 +/- 3.4 to a maximum of 0.30 +/- 3.3 at the third postinjection month (P < 0.01). Mean improvements in visual acuity measured were 2.15 +/- 1.66, 2.42 +/- 2.66, 1.13 +/- 2.74, 0.96 +/- 2.01 and 0.08 +/- 2.34 lines at the 1, 3, 6, 9 and 12 months follow-up intervals, respectively. In all eyes in fluorescein angiography, macular oedema was resolved (63%) or decreased (37%) during the follow up. However, the macular oedema reached the pretreatment level in 29 (49%) of the eyes at 6 months and 15 of 21 eyes (71%) at 9 months after injection. Intraocular pressure exceeded 21 mmHg in 10 eyes, which were controlled by topical medication. Four eyes showed cataract progression. Endophthalmitis was not observed in any of the eyes.

CONCLUSIONS

Intravitreal injection of 4 mg triamcinolone acetonide appears to be an effective and relatively safe therapeutic method for diffuse diabetic macular oedema. Further studies are warranted to assess the long-term efficacy, safety and the need for reinjection.

A reassessment of vascular endothelial growth factor in central nervous system pathology

✓ Overexpression of vascular endothelial growth factor (VEGF) is associated with several central nervous system (CNS) diseases and abnormalities, and is often postulated as a causative factor and promising therapeutic target in these settings. The authors' goal was to reassess the contribution of VEGF to the biology and pathology of the CNS.

The authors review the literature relating to the following aspects of VEGF: 1) the biology of VEGF in normal brain; 2) the involvement of VEGF in CNS disorders other than tumors (traumatic and ischemic injuries, arteriovenous malformations, inflammation); and 3) the role of VEGF in brain tumor biology (gliomas and the associated vasogenic edema, and hemangioblastomas).

The authors conclude the following: first, that VEGF overexpression contributes to the phenotype associated with many CNS disorders, but VEGF is a reactive rather than a causative factor in many cases; and second, that use of VEGF as a therapeutic agent or target is complicated by the effects of VEGF not only on the cerebral vasculature, but also on astrocytes, neurons, and inflammatory cells. In many cases, therapeutic interventions targeting the VEGF/VEGF receptor axis are likely to be ineffective or even detrimental. Clinical manipulation of VEGF levels in the CNS must be approached with caution.

Intravitreal triamcinolone compared with macular laser grid photocoagulation for the treatment of cystoid macular edema

PURPOSE

To evaluate the outcome of cystoid macular edema (CME) treated with intravitreal injections of triamcinolone acetonide (TA), macular laser grid photocoagulation (MLG), or both (TA+MLG).

DESIGN

Prospective, randomized, interventional, parallel, three-arm clinical trial.

METHODS

SETTING

Institutional clinical study.

PATIENTS

Fifty-six patients (63 eyes) affected by diabetic or retinal vein occlusion CME.

PROCEDURES

Twenty-two eyes received intravitreal injections of 4 mg TA; 21 eyes underwent MLG; and 20 eyes received intravitreal injection of 4 mg TA, and after 3 months, MLG.

MAIN OUTCOME MEASURES

Best-corrected visual acuity (VA), central macular thickness (CMT) (by optical coherence tomography), and postoperative complications.

RESULTS

Mean follow-up was 9 +/- 2 months (range 6 to 12 months). Baseline VA (logarithm of minimal angle of resolution [logMAR]) and CMT were, respectively, 0.82 +/- 0.19 and 556 +/- 139 microm microns for the TA group, 0.84 +/- 0.15 and 601 +/- 102 microm microns for the MLG group, and 0.83 +/- 0.22 and 573 +/- 106 microm microns for the TA+MLG group (no statistically significant difference among the groups). After the treatment, at 45 days, 3, 6, and 9 months in the TA group, VA had improved (P = .004) by 0.26, 0.25, 0.22, and 0.23 logMAR and CMT had decreased by 37%, 33%, 29%, and 31% (P = < .001). In the MLG group, VA was unchanged although CMT had decreased by 5%, 13%, 14%, and 16% (P = .021). In the TA+MLG group, VA had improved (P = .003) by 0.26, 0.24, 0.19, and 0.20 logMAR, and CMT had decreased by 36%, 34%, 28%, and 29% (P = < .001). The groups receiving triamcinolone had better VA and lower CMT values at all time points (P < .05). A reinjection was performed in eight eyes; intraocular pressure increased in nine eyes (treated with medical therapy), and cataract progressed in one eye. No injection-related complications occurred.

CONCLUSIONS

TA intravitreal injection improves VA and reduces CMT more than MLG, which in triamcinolone-treated eyes does not offer further advantages. Intravitreal TA injection could be used as primary treatment in patients with CME.

Intravitreal triamcinolone injection for chronic diabetic macular oedema with severe hard exudates

BACKGROUND

The purpose of the study was to determine the efficacy and safety of intravitreal triamcinolone acetonide (TA) in chronic diabetic macular oedema with severe hard exudates.

METHODS

This prospective, interventional consecutive case series study consisted of 33 eyes of 28 patients with chronic diabetic macular oedema and severe foveal hard exudates who received an intravitreal injection of 4 mg of TA. The patients were divided into two groups according to the type of foveal hard exudates: group I, plaque-like (17 eyes) and group II, dot-like scattered hard exudates (16 eyes). The results of both groups, evaluated by colour fundus photography and fluorescein angiography, were compared and complications were recorded.

RESULTS

All patients completed at least 6 months of follow-up. In all eyes, the hard exudates were completely resolved (24% in group I and 50% in group II) or decreased (76% in group I and 50% in group II). In group I, the mean diameter of the exudates plaques significantly decreased from 5.5+/-3.8 mm(2) in the pre-treatment period to 2.2+/-2.7 mm(2) at the end of the follow-up period. There was no recurrence of the hard exudates in either of the groups. The mean +/- SD visual acuity (VA) improved from 0.07+/-2.5 at the baseline to a maximum of 0.09+/-2.1 lines in group I (P<0.01) and from 0.13+/-3.9 to a maximum of 0.27+/-2.7 lines in group II (P<0.01). The mean VA improvement in group II was better than group I (3.2+/-2.5 vs. 1.4+/-1.0 lines, P<0.05). Intraocular pressure exceeded 21 mmHg in 10 eyes (30%), which was then controlled by topical medication. Three eyes (9%) exhibited signs of subcapsular cataract progression.

CONCLUSIONS

Intravitreal TA appears to be a valuable treatment in chronic diabetic macular oedema with severe foveal hard exudates. In all eyes in this study the hard exudates were completely resolved or decreased, and the mean VA improved significantly in both groups. However, the VA improvement was significantly worse in eyes with plaque-like exudates suggesting the possible value of earlier treatment. Further studies would enable the assessment of the universal effectiveness of this treatment.

Verteporfin therapy in combination with triamcinolone: published studies investigating a potential synergistic effect

Evidence from randomized, placebo-controlled, double-masked studies has demonstrated that verteporfin (Visudyne) therapy is effective in reducing the risk of visual acuity loss in selected groups of patients with choroidal neovascularization (CNV) due to age-related macular degeneration (AMD). Pilot studies of intravitreal triamcinolone acetonide monotherapy revealed promising results in patients with CNV due to AMD, but the visual acuity outcomes in a randomized, controlled study were lower than anticipated. Recently, however, there has been growing interest in the adjunctive use of triamcinolone to improve visual acuity and reduce regrowth of CNV in patients receiving verteporfin therapy. This review article surveys the currently available evidence, based on a Medline search covering the years 1980-2005 and abstracts from recent scientific meetings. A number of small-scale, uncontrolled pilot studies have indicated that the combination of triamcinolone acetonide with verteporfin therapy may be beneficial. Evidence is now needed from randomized, controlled studies to determine whether the potential benefits of combination therapy outweigh the possible risks of increased intraocular pressure, endophthalmitis, and progression of cataract that have been observed in trials of triamcinolone monotherapy.

The effects of exogenous nitric oxide donor on motor functional recovery of reperfused peripheral nerve

PURPOSE

To investigate the effects of the nitric oxide donor S-nitroso-N-acetylcysteine (SNAC) on motor functional recovery of reperfused rat sciatic nerve.

METHODS

Seventy-eight rats were divided into groups treated with SNAC (100 nmol/100 g/min), methylprednisolone 30 mg/kg/h for 15 minutes, 45-minute pause, 5.4 mg/kg/h for 1.5 h), and phosphate-buffered saline 0.2 mL/100 g/h). A 1-cm segment of sciatic nerve had 2 hours of ischemia and the results were evaluated after various reperfusion periods using a walking track test, muscle contractile testing, muscle weight, and histology.

RESULTS

During reperfusion there was a significant overall improvement in sciatic functional index measurement and isometric titanic contractile force for the SNAC-treated group compared with the methylprednisolone- and phosphate-buffered saline- treated groups. The SNAC group had significantly earlier improvement in the sciatic functional index measurement between days 7 and 28. Restoration of the contractile force and muscle weight of the extensor digitorum longus muscle began earlier in the SNAC group--after day 11--whereas the other 2 groups showed progressive atrophy until day 21, with a significant difference between the SNAC group and the other 2 groups. Histologic examination showed that SNAC-treated rats had less severe degeneration and earlier regeneration of axons than the others. Although methylprednisolone-treated rats showed earlier recovery than phosphate-buffered saline-treated rats in all parameters there were no significant differences between these 2 groups.

CONCLUSIONS

Supplementation of nitric oxide is effective in promoting motor functional recovery of the reperfused peripheral nerve and has potential to replace or augment steroids as therapeutic agents in treatment of nervous system ischemia/reperfusion injury.

Permeability studies on in vitro blood-brain barrier models: physiology, pathology, and pharmacology

(1) The specifically regulated restrictive permeability barrier to cells and molecules is the most important feature of the blood-brain barrier (BBB). The aim of this review was to summarize permeability data obtained on in vitro BBB models by measurement of transendothelial electrical resistance and by calculation of permeability coefficients for paracellular or transendothelial tracers. (2) Results from primary cultures of cerebral microvascular endothelial cells or immortalized cell lines from bovine, human, porcine, and rodent origin are presented. Effects of coculture with astroglia, neurons, mesenchymal cells, blood cells, and conditioned media, as well as physiological influence of serum components, hormones, growth factors, lipids, and lipoproteins on the barrier function are discussed. (3) BBB permeability results gained on in vitro models of pathological conditions including hypoxia and reoxygenation, neurodegenerative diseases, or bacterial and viral infections have been reviewed. Effects of cytokines, vasoactive mediators, and other pathogenic factors on barrier integrity are also detailed. (4) Pharmacological treatments modulating intracellular cyclic nucleotide or calcium levels, and activity of protein kinases, protein tyrosine phosphatases, phospholipases, cyclooxygenases, or lipoxygenases able to change BBB integrity are outlined. Barrier regulation by drugs involved in the metabolism of nitric oxide and reactive oxygen species, as well as influence of miscellaneous treatments are also listed and evaluated. (5) Though recent advances resulted in development of improved in vitro BBB model systems to investigate disease modeling, drug screening, and testing vectors targeting the brain, there is a need for checking validity of permeability models and cautious interpretation of data.

Posterior subtenon triamcinolone acetonide for refractory diabetic macular edema

PURPOSE

To evaluate posterior subtenon injection of triamcinolone acetonide for refractory diabetic macular edema (DME).

DESIGN

Retrospective, interventional, case series.

METHODS

SETTING

Clinical practice.

PATIENT POPULATION

Patients with persistent clinically significant DME involving the center of the fovea 3 or more months after one or more treatments of focal macular photocoagulation were included. Exclusion criteria were a history of corticosteroid-responsive intraocular pressure (IOP) rise, intraocular surgery within 3 months, and any laser treatment within 1 month.

PROCEDURE

All patients received an ophthalmic history and examination including best-corrected Snellen visual acuity, IOP measurement, anterior segment examination including evaluation of lens status with LOCS II criteria, dilated fundus examination, and a posterior subtenon injection of 40 mg triamcinolone acetonide at baseline. Patients were reevaluated at 1, 3, 6, and 12 months after injection.

RESULTS

Seventy-three injections were performed in 63 eyes of 50 patients. The mean baseline visual acuity was 20/80. Mean visual acuity significantly improved to 20/50 at 1 month, then stabilized to 20/65 at 3 months, 20/68 at 6 months, and 20/63 at 12 months. Complications were rare, with a transient significant rise in intraocular pressure at the 3-month evaluation and ptosis in two patients.

CONCLUSIONS

Visual acuities remained stable or improved over a 12-month period after posterior subtenon triamcinolone injections for refractory DME. There was a statistically significant improvement in visual acuity at 1 month.

Steroid effects on osteogenesis through mesenchymal cell gene expression

We have studied the mechanism of steroid-induced osteonecrosis by examining the effect of dexamethasone on a multipotential cell line, D1, which is derived from bone marrow and is capable of differentiating into either the osteoblast or the adipocyte lineage. The expression of bone cell and fat cell transcription factors Cbfa1/Runx2 and PPARgamma2, were determined. Osteocalcin promoter activity was measured by co-transfecting the cells with the phOC-luc and pSV beta-Gal plasmids. Dexamethasone increased PPARgamma2 gene expression 2-fold, while Cbfa1/Runx2 gene expression and osteocalcin promoter activity decreased by 50-60%, and VEGF protein, measured by ELISA, decreased by 55%. These changes indicate enhanced adipogenesis and decreased osteogenesis by mesenchymal cells in vitro, together with a decrease in VEGF, a potent angiogeneic factor, suggesting that dexamethasone may shunt uncommitted osteoprogenitor cells in marrow from osteoblastic differentiation into the adipocytic pathway, leading to diminished vascularization and eventual osteonecrosis.

Intravitreal triamcinolone acetonide for diabetic diffuse macular edema: preliminary results of a prospective controlled trial

OBJECTIVE

To evaluate prospectively the efficacy and safety of 1 intravitreal injection of 4 mg of triamcinolone acetonide for refractory diffuse diabetic macular edema.

DESIGN

Interventional case series.

PARTICIPANTS

Fifteen patients with bilateral diabetic macular edema unresponsive to laser photocoagulation. In all patients, one eye received the injection, and the other served as a control.

INTERVENTION

Intravitreal injection of 4 mg of triamcinolone acetonide under subconjunctival anesthesia.

MAIN OUTCOME MEASURES

The main outcome measure was central macular thickness (CMT) at 1, 3, and 6 months, measured by optical coherence tomography. Secondary outcomes were Early Treatment Diabetic Retinopathy Study (ETDRS) scores, intraocular pressure, and cataract progression.

RESULTS

In this preliminary report, we give the results for 12 patients who had a follow-up of at least 3 months. Seven of them were followed up for 6 months. Before injection, CMT was 509.6+/-143.5 microm (mean +/- standard deviation [SD]) in injected eyes, versus 474.4+/-82.6 microm in control eyes. Four weeks after injection, it was 207.3+/-44.2 microm in injected eyes and 506.7+/-122.4 microm in control eyes (P<0.001, bilateral Wilcoxon test for paired samples), and after 12 weeks, 207+/-96.7 microm and 469.3+/-117.6 microm, respectively (P = 0.005). The difference between the CMTs of injected and control eyes was no longer significant at 24 weeks because of the recurrence of macular edema in 5 of 12 injected eyes. Before triamcinolone injection, the ETDRS score was 47.8+/-13 (mean +/- SD; range, 28-66) in injected eyes, versus 51.9+/-14.6 (range, 31-71) in control eyes. Twelve weeks thereafter, the corresponding values were 52.7+/-10.8 (range, 34-70) and 50.8+/-14.3 (range, 29-69), respectively, and at 24 weeks, 54.7+/-7.6 (range, 47-68) and 50.6+/-18.4 (range, 28-71). At no time was the difference between the ETDRS scores for injected and control eyes significant. In 6 of the 12 injected eyes, intraocular pressure exceeded 25 mmHg, and was controlled by topical medication.

CONCLUSION

Intravitreal injection of triamcinolone effectively reduces macular thickening due to diffuse diabetic macular edema, at least in the short term. Further studies are required to demonstrate that it provides visual benefit.

Testosterone up-regulates aquaporin-4 expression in cultured astrocytes

Aquaporin-4 (AQP4) is located on astrocyte endfeet that face blood vessels in the brain and in the pia. It is thought to play a crucial role in the development of brain edema. To confirm the notion that sex steroids and dexamethasone influence brain edema through AQP4 regulation, we investigated the effects of 17beta-estradiol, testosterone, and dexamethasone on the expression of AQP4 in cultured astrocytes. Testosterone significantly up-regulated AQP4 at the level of both protein and mRNA. At a concentration of 100 nM, testosterone significantly increased AQP4 protein levels and ameliorated the osmotic fragility of astrocytes from hypoosmotic stress, suggesting that the increased levels of AQP4 facilitated the testosterone function. Moreover, this effect was attenuated by the protein kinase C activator 12-O-tetradecanoylphorbol 13-acetate, which can rapidly decrease AQP4 mRNA expression, indicating that the response was specific. These results indicate that AQP4 can alter the osmotic fragility of astrocytes and that testosterone can influence brain edema through AQP4 regulation, whereas 17beta-estradiol and dexamethasone cannot.

Expression of transforming growth factor-beta1 and hypoxia-inducible factor-1alpha in an experimental model of kidney transplantation

BACKGROUND

Ischemia-reperfusion syndrome has been recognized as an important pathogenic factor in renal transplantation, not only in the development of delayed graft function but also in the development of acute and chronic rejection. Hypoxia-inducible factor (HIF)-1 activates transcription of several genes implicated in cell survival, such as vascular endothelial growth factor (VEGF), and in tissue repair transforming growth factor (TGF)-beta. The purpose of this study was to characterize TGF-beta1, VEGF, and HIF-1alpha expression profiles during renal transplantation with heart-beating donors (HBD) and non-heart-beating donors (NHBD).

METHODS

An experimental model of renal transplantation using 40 pairs of large, white, Landrace pigs and including HBD and NHBD was used. Cold-ischemia time was the same in all groups (6 hr), and three groups of NHBD (30, 45, and 90 min) were studied. Immunosuppressive therapy consisted of cyclosporine, except in one HBD group, which was treated with azathioprine. TGF-beta1, VEGF, and HIF-1alpha expression profiles were performed in renal biopsies obtained at different times: after anesthetic induction (basal); 30, 45, and 90 min after warm ischemia; after cold ischemia; 1 hr after reperfusion; and 5 days after transplantation.

RESULTS

TGF-beta1 expression increased after cold ischemia in HBD and remained unaltered during the surgical process in all NHBD groups. HIF-1alpha and VEGF expression were not greatly modified during surgery in the HBD or NHBD groups. All groups showed a significant increase in TGF-beta1 and HIF-1alpha expression as well as down-regulation of VEGF 5 days after transplantation, and these effects were independent of immunosuppressive treatment. There were no statistically significant differences among the groups at 5 days after transplantation, although the increase in TGF-beta1 was more pronounced in the HBD groups, especially in azathioprine-treated animals.

CONCLUSIONS

The initial up-regulation of TGF-beta1 observed in HBD immediately after cold ischemia could have a positive effect on epithelial-tubular regeneration. Warm ischemia has a detrimental effect on TGF-beta1 expression during the early phases of renal transplantation and has no effect on VEGF and HIF-1alpha expression. The up-regulation of TGF-beta1 and HIF-1alpha observed after transplantation could have a positive effect on tubular repair. TGF-beta1 expression was lower in animals treated with cyclosporine, probably because of cellular toxicity.

Implications of vascular endothelial growth factor, sFlt-1, and sTie-2 in plasma, serum and cerebrospinal fluid during cerebral ischemia in man

The relation between cerebral ischemia and local release of angiogenic factors was investigated after subarachnoid hemorrhage (SAH) in humans. Time-dependent concentration-changes of vascular endothelial growth factor (VEGF), sFlt-1 and sTie-2 extracted from plasma, serum, and cerebrospinal fluid (ventricular, cisternal, and lumbar) were analyzed in 15 patients surgically treated for ruptured aneurysms of the anterior circulation (Hunt and Hess grades I-V). Data were related to brain Po2 (Pbro2) and cerebral energy metabolites (extracellular lactate, pyruvate, glutamate, and glycerin concentrations) as well as clinical and radiologic reference data. Delayed impairment of cerebral perfusion secondary to progressive microcirculatory alterations was associated with reduced local Pbro2 and energy metabolism (increased lactate-pyruvate ratio, glutamate and glycerine levels). Elevated serum/plasma and CSF concentrations of VEGF, sFlt-1, and sTie-2 matched the scale of ischemic tissue hypoxia. Excessive VEGF/sFlt-1 and sTie-2 levels were related to Pbro2 values consistently less than 5 mm Hg, glutamate concentrations greater than 300 micromol/L, lactate-pyruvate ratio greater than 300, cerebral infarction, and reduced outcome (P < 0.01). Delayed microcirculatory impairment was mirrored by distinct elevation of cisternal and arterial VEGF and sFlt-1 concentrations, suggesting local induction of angiogenesis. Arterial levels of VEGF, sFlt-1, and sTie-2 reflect both extent and time course of compensatory, yet clinically inefficient, angiogenesis in the absence of general hypoxia.

Glucocorticoids inhibit vascular endothelial growth factor expression in growth plate chondrocytes

Vascular endothelial growth factor (VEGF) plays an essential role in angiogenesis in the growth plate and ultimately in regulating endochondral ossification. Since longitudinal bone growth is often disturbed in children who are treated with glucocorticoids, we investigated the effects of dexamethasone on VEGF expression by epiphyseal chondrocytes. Cells were cultured from tibial growth plates of neonatal piglets. Using Northern blotting and RT-PCR techniques, the chondrocyte-specific markers aggrecan, collagen II and CD-RAP were detected. Also the glucocorticoid receptor (GR) was expressed. VEGF protein secreted from these cells was examined by ELISA and Western immunoblotting. The VEGF(121) and VEGF(165) isoforms were detected in the supernatant. As determined by RT-PCR, all three major mRNA splice variants were produced, including the species encoding VEGF(189). Dexamethasone (100 nM) inhibited both protein and mRNA expression by approximately 45%. Hydrocortisone (cortisol) and prednisolone also inhibited VEGF secretion, but they were less active than dexamethasone. The inhibitory actions of dexamethasone were almost completely blocked by the GR antagonist Org34116, indicating that the GR mediates these actions. Degradation of the VEGF mRNA was not accelerated by dexamethasone. Therefore, a transcriptional mechanism seems likely. Downregulation of this important growth factor could lead to disruption of the normal invasion of blood vessels in the growth plate, which could contribute to disturbed endochondral ossification and growth.

Vascular endothelial growth factor: the key mediator in pleural effusion formation

Pleural effusion is common in clinical practice. Increased vascular permeability and leakage play a principal role in the development of exudative pleural effusions. In vitro and in vivo evidence have solidly established vascular endothelial growth factor (VEGF), a potent inducer of vascular permeability, as a crucial mediator in pleural fluid formation. VEGF is present in high quantities in human effusions. In the pleural space, mesothelial cells, infiltrating inflammatory cells, and (in malignant pleuritis) cancer cells contribute to the VEGF accumulation in the pleural fluids. Pleural fluid VEGF is biologically active and may promote tumor growth and chemotaxis. Strategies to antagonize the VEGF activity at various target points of its signaling pathway have shown success in vitro and in animal models of malignant pleural or peritoneal effusions. Novel agents targeting VEGF activities are undergoing clinical trials. Regulation of VEGF activity and vascular permeability represent a rapidly expanding field of research, which is likely to provide further insight in the pathophysiology of pleural fluid formation.

Budesonide reduces vascular endothelial growth factor secretion and expression in airway (Calu-1) and alveolar (A549) epithelial cells

Vascular endothelial growth factor (VEGF), a cytokine expressed in the respiratory epithelial cells, induces vascular hyperpermeability and edema, symptoms that are alleviated by budesonide, an anti-asthma corticosteroid. However, modulation of VEGF levels by budesonide in the respiratory epithelium has not been studied. In this study, we investigated the mechanisms of VEGF secretion using brefeldin A and monensin in human airway (Calu-1) and alveolar (A549) epithelial cells, and further determined whether budesonide inhibits VEGF secretion and mRNA expression through a glucocorticoid receptor-mediated mechanism. In both cell types, VEGF secretion was inhibited by brefeldin A and monensin, suggesting vesicular transport of VEGF through endoplasmic reticulum (ER)-golgi pathway. At concentrations devoid of cytotoxicity, budesonide reduced VEGF secretion and VEGF mRNA expression in both cell types and these effects were inhibited by mifepristone (RU 486), a glucocorticoid receptor antagonist, suggesting that budesonide reduces VEGF secretion and expression through its glucocorticoid receptor-mediated action. Also, budesonide-mediated inhibition of VEGF mRNA was time- and protein synthesis-dependent. Thus, budesonide may be of potential value in treating disorders of the respiratory tract that are associated with VEGF elevation.