VEGF and TGF-β are required for the maintenance of the choroid plexus and ependyma

Although the role of vascular endothelial growth factor (VEGF) in developmental and pathological angiogenesis is well established, its function in the adult is less clear. Similarly, although transforming growth factor (TGF) β is involved in angiogenesis, presumably by mediating capillary (endothelial cell [EC]) stability, its involvement in quiescent vasculature is virtually uninvestigated. Given the neurological findings in patients treated with VEGF-neutralizing therapy (bevacizumab) and in patients with severe preeclampsia, which is mediated by soluble VEGF receptor 1/soluble Fms-like tyrosine kinase receptor 1 and soluble endoglin, a TGF-β signaling inhibitor, we investigated the roles of VEGF and TGF-β in choroid plexus (CP) integrity and function in adult mice. Receptors for VEGF and TGF-β were detected in adult CP, as well as on ependymal cells. Inhibition of VEGF led to decreased CP vascular perfusion, which was associated with fibrin deposition. Simultaneous blockade of VEGF and TGF-β resulted in the loss of fenestrae on CP vasculature and thickening of the otherwise attenuated capillary endothelium, as well as the disappearance of ependymal cell microvilli and the development of periventricular edema. These results provide compelling evidence that both VEGF and TGF-β are involved in the regulation of EC stability, ependymal cell function, and periventricular permeability

Endogenous VEGF Is Required for Visual Function: Evidence for a Survival Role on Müller Cells and Photoreceptors

Vascular endothelial growth factor (VEGF) is well known for its role in normal and pathologic neovascularization. However, a growing body of evidence indicates that VEGF also acts on non-vascular cells, both developmentally as well as in the adult. In light of the widespread use of systemic and intraocular anti-VEGF therapies for the treatment of angiogenesis associated with tumor growth and wet macular degeneration, systematic investigation of the role of VEGF in the adult retina is critical.Using immunohistochemistry and Lac-Z reporter mouse lines, we report that VEGF is produced by various cells in the adult mouse retina and that VEGFR2, the primary signaling receptor, is also widely expressed, with strong expression by Müller cells and photoreceptors. Systemic neutralization of VEGF was accomplished in mice by adenoviral expression of sFlt1. After 14 days of VEGF neutralization, there was no effect on the inner and outer retina vasculature, but a significant increase in apoptosis of cells in the inner and outer nuclear layers. By four weeks, the increase in neural cell death was associated with reduced thickness of the inner and outer nuclear layers and a decline in retinal function as measured by electroretinograms. siRNA-based suppression of VEGF expression in a Müller cell line in vitro supports the existence of an autocrine role for VEGF in Müller cell survival. Similarly, the addition of exogenous VEGF to freshly isolated photoreceptor cells and outer-nuclear-layer explants demonstrated VEGF to be highly neuroprotective.These results indicate an important role for endogenous VEGF in the maintenance and function of adult retina neuronal cells and indicate that anti-VEGF therapies should be administered with caution

TGF-β Is Required for Vascular Barrier Function, Endothelial Survival and Homeostasis of the Adult Microvasculature

Pericyte-endothelial cell (EC) interactions are critical to both vascular development and vessel stability. We have previously shown that TGF-β signaling between EC and mural cells participates in vessel stabilization in vitro. We therefore investigated the role of TGF-β signaling in maintaining microvessel structure and function in the adult mouse retinal microvasculature. TGF-β signaling was inhibited by systemic expression of soluble endoglin (sEng) and inhibition was demonstrated by reduced phospho-smad2 in the adult retina. Blockade of TGF-β signaling led to increased vascular and neural cell apoptosis in the retina, which was associated with decreased retinal function, as measured by electroretinogram (ERG). Perfusion of the inner retinal vasculature was impaired and was accompanied by defective autoregulation and loss of capillary integrity. Fundus angiography and Evans blue permeability assay revealed a breakdown of the blood-retinal-barrier that was characterized by decreased association between the tight junction proteins zo-1 and occludin. Inhibition of TGF-β signaling in cocultures of EC and 10T1/2 cells corroborated the in vivo findings, with impaired EC barrier function, dissociation of EC from 10T1/2 cells, and endothelial cell death, supporting the role of EC-mesenchymal interactions in TGF-β signaling. These results implicate constitutive TGF-β signaling in maintaining the integrity and function of the adult microvasculature and shed light on the potential role of TGF-β signaling in vasoproliferative and vascular degenerative retinal diseases

Phase 3, Randomized, 20-Month Study of the Efficacy and Safety of Bimatoprost Implant in Patients with Open-Angle Glaucoma and Ocular Hypertension (ARTEMIS 2)

Objective- To evaluate the intraocular pressure (IOP)-lowering efficacy and safety of 10 and 15 µg bimatoprost implant in patients with open-angle glaucoma (OAG) or ocular hypertension (OHT). Methods- This randomized, 20-month, multicenter, masked, parallel-group, phase 3 trial enrolled 528 patients with OAG or OHT and an open iridocorneal angle inferiorly in the study eye. Study eyes were administered 10 or 15 µg bimatoprost implant on day 1, week 16, and week 32, or twice-daily topical timolol maleate 0.5%. Primary endpoints were IOP and IOP change from baseline through week 12. Safety measures included treatment-emergent adverse events (TEAEs) and corneal endothelial cell density (CECD). Results- Both 10 and 15 µg bimatoprost implant met the primary endpoint of noninferiority to timolol in IOP lowering through 12 weeks. Mean IOP reductions from baseline ranged from 6.2–7.4, 6.5–7.8, and 6.1–6.7 mmHg through week 12 in the 10 µg implant, 15 µg implant, and timolol groups, respectively. IOP lowering was similar after the second and third implant administrations. Probabilities of requiring no IOP-lowering treatment for 1 year after the third administration were 77.5% (10 µg implant) and 79.0% (15 µg implant). The most common TEAE was conjunctival hyperemia, typically temporally associated with the administration procedure. Corneal TEAEs of interest (primarily corneal endothelial cell loss, corneal edema, and corneal touch) were more frequent with the 15 than the 10 µg implant and generally were reported after repeated administrations. Loss in mean CECD from baseline to month 20 was ~ 5% in 10 µg implant-treated eyes and ~ 1% in topical timolol-treated eyes. Visual field progression (change in the mean deviation from baseline) was reduced in the 10 µg implant group compared with the timolol group. Conclusions- The results corroborated the previous phase 3 study of the bimatoprost implant. The bimatoprost implant met the primary endpoint and effectively lowered IOP. The majority of patients required no additional treatment for 12 months after the third administration. The benefit-risk assessment favored the 10 over the 15 µg implant. Studies evaluating other administration regimens with reduced risk of corneal events are ongoing. The bimatoprost implant has the potential to improve adherence and reduce treatment burden in glaucoma

GLAUCOMA DRAINAGE DEVICE COMPLICATED BY FUNGAL PARACONIOTHYRIUM ENDOPHTHALMITIS

Ten years after BaerveldtTM implantation, a woman underwent immunosuppressive therapy for necrotizing scleritis. She subsequently developed symptoms suggestive of endophthalmitis in the setting of tube exposure. Cultures isolated fungal Paraconiothyrium. She underwent two vitrectomies with anterior chamber washouts, BaerveldtTM device removal, and intraocular and systemic antifungal therapy. The endophthalmitis has since resolved.   Purpose: To report the first documented case of Paraconiothyrium fungal endophthalmitis associated with a glaucoma drainage device. Methods: A 74-year-old woman with a history of primary open angle glaucoma had undergone BaerveldtTM glaucoma implantation 10 years earlier. She presented with pain and injection, was diagnosed with necrotizing scleritis, and started on prednisone and methotrexate. She subsequently developed worsening pain, vision loss, and infiltrates suggestive of fungal endophthalmitis, in the setting of an exposed BaerveldtTM tube. Results: Surgical cultures were positive for fungal Paraconiothyrium. The patient underwent two pars plana vitrectomies, anterior chamber washouts, removal of the BaerveldtTM device and intraocular lens, and intraocular and systemic antifungal therapy. The fungal infiltrates and inflammation have since resolved. Conclusions: Fungal endophthalmitis is an exceedingly rare complication of glaucoma drainage device implantation, but must be considered, especially in an immunocompromised patient

Fibromyxoma masquerading as dacryocystitis

Primary tumors of the lacrimal sac are extremely rare and predominantly epithelial in origin. We report a unique case of fibromyxoma of the lacrimal sac in an 86-year-old Caucasian woman who presented with 3 months of lower eyelid edema and 1 week of purulent discharge, epiphora, and acute pain. Examination revealed right lower eyelid erythema/edema and a tender, firm, palpable mass of the right lacrimal sac, which self-expressed a yellow, purulent discharge. On surgical exploration, a firm, rubbery, yellow mass was encountered and excised. Histopathologic analysis identified a nonencapsulated mass composed of loose interlacing fascicles and bundles of spindle-shaped cells with prominent myxoid changes; immunostaining was strongly positive for vimentin, weakly for smooth muscle actin, and negative for S-100 and muscle-specific actin. These findings were consistent with the diagnosis of a fibromyxoma of the lacrimal drainage system. After excision, the patient did well, with resolution of dacryocystitis

Glaucoma Drainage Device Erosions in Patients Receiving Anti-Vascular Endothelial Growth Factor Therapy for Diabetic Retinopathy

Purpose: To determine if intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections are associated with an increased risk of glaucoma drainage device (GDD) erosions. Patients and Methods: A retrospective chart review was conducted including patients with diabetic retinopathy and had a GDD implanted at a large academic institution. The rate of GDD erosions was compared between eyes that did or did not receive intravitreal anti-VEGF injections. A subanalysis was also performed the relationship between diabetic macular edema (DME) and intravitreal steroid injections and GDD erosions. Results: A total of 677 eyes from 608 patients was included. A total of 447 eyes received at least one anti-VEGF injection; 230 eyes never received such therapy. Twenty eyes (4.5%) receiving anti-VEGF had at least one erosion event, compared to 7 eyes (3.0%) of patients not receiving anti-VEGF therapy (OR 1.49, p=0.37). Diabetic macular edema was associated with a significantly increased rate of erosion in eyes not receiving anti-VEGF (71.4% versus 31.4%, p=0.034), but not in eyes receiving anti-VEGF (30.0% versus 40.7%, p=0.34). Receiving more than one specific anti-VEGF agent, an increased frequency or total number of anti-VEGF injections, or receiving intravitreal steroids were not associated with an increased risk of erosion (p>0.05). Conclusion: In patients with diabetic retinopathy, the use of anti-VEGF does not result in an increased rate of GDD erosions or recurrent erosions. Further research is needed over a longer follow-up period to determine if longer or more frequent anti-VEGF treatment is a risk factor for recurrent erosions

Inhibition of VEGF or TGF-β Signaling Activates Endothelium and Increases Leukocyte Rolling

OBJECTIVE: Motivated by the central roles that VEGF and TGF-β play in the assembly and maintenance of the vasculature, we examined the impact of systemic VEGF or TGF-β signal inhibition on endothelial activation as detected by leukocyte-endothelial interactions. METHODS AND RESULTS: VEGF or TGF-β inhibition, accomplished using adenovirus expression of soluble Flt1 (Ad-sFlt1) or soluble endoglin (Ad-sEng), resulted in a significant increase in the number of leukocytes rolling along the mesenteric venous endothelium and a significant decrease in rolling velocity in Ad-sEng mice. Neutralization of VEGF or TGF-β resulted in endothelial surface expression of P-selectin and impaired peripheral vasodilatation. Neither inhibition of VEGF nor TGF-β was associated with platelet or leukocyte activation, as detected by the activation markers platelet P-selectin and the active integrin - αIIbβIII, or by leukocyte expression of L-selectin. Soluble VCAM-1 and E-selectin were increased in sEng-expressing mice, indicating higher levels of these adhesion receptors. CONCLUSIONS: VEGF or TGF-β neutralization results in impaired endothelium-mediated vasodilatation and elevated expression of surface adhesion molecules, resulting in increased leukocyte adhesion. These results indicate an essential role for both VEGF and TGF-β in maintaining the endothelium in a non-activated state and have implications for therapeutic approaches that neutralize VEGF or TGF-β

Inhibition of VEGF or TGF- Signaling Activates Endothelium and Increases Leukocyte Rolling

Objective Motivated by the central roles that VEGF and TGF-β play in the assembly and maintenance of the vasculature, we examined the impact of systemic VEGF or TGF-β signal inhibition on endothelial activation as detected by leukocyte-endothelial interactions. Methods and Results VEGF or TGF-β inhibition, accomplished using adenovirus expression of soluble Flt1 (Ad-sFlt1) or soluble endoglin (Ad-sEng), resulted in a significant increase in the number of leukocytes rolling along the mesenteric venous endothelium and a significant decrease in rolling velocity in Ad-sEng mice. Neutralization of VEGF or TGF-β resulted in endothelial surface expression of P-selectin and impaired peripheral vasodilatation. Neither inhibition of VEGF nor TGF-β was associated with platelet or leukocyte activation, as detected by the activation markers platelet P-selectin and the active integrin - αIIbβIII, or by leukocyte expression of L-selectin. Soluble VCAM-1 and E-selectin were increased in sEng-expressing mice, indicating higher levels of these adhesion receptors. Conclusions VEGF or TGF-β neutralization results in impaired endothelium-mediated vasodilatation and elevated expression of surface adhesion molecules, resulting in increased leukocyte adhesion. These results indicate an essential role for both VEGF and TGF-β in maintaining the endothelium in a non-activated state and have implications for therapeutic approaches that neutralize VEGF or TGF-β