Expression of advanced glycation end products and related molecules in diabetic fibrovascular epiretinal membranes

Elevated aqueous TNF-α levels are associated with more severe functional and anatomic findings in eyes with diabetic macular oedema

BACKGROUND

Intravitreal ranibizumab for diabetic macular oedema (DMO) has been recently shown to modulate levels of aqueous cytokines. This study investigates the associations between changes in aqueous cytokine levels following intravitreal ranibizumab therapy and the corresponding anatomical and functional changes in the eye.

METHODS

Twenty-five patients comprising 30 eyes diagnosed with DMO were prospectively recruited. All eyes received three loading dose ranibizumab injections at baseline, week 4 and week 8, followed by pro re nata treatment based on best-corrected visual acuity (BCVA) and central macular thickness (CMT) up to week 48. Prior to ranibizumab administration, aqueous samples were collected from all eyes, and subsequent sampling was performed at week 8. Levels of 32 cytokines were assessed at baseline and at week 8.

RESULTS

At baseline, higher aqueous TNF-α levels were associated with poorer BCVA (p = 0.033), greater macular volume (p = 0.017) and worse diabetic retinopathy (p = 0.047). Higher levels of IL-7 were associated with poorer BCVA and greater macular volume (MV). Following treatment with ranibizumab there was a significant correlation with reduction of aqueous TNF-α and improvements in BCVA and MV, both at 6 months (BCVA [r = -0.558, p = 0.001], MV [r = 0.410, p = 0.024]) and 12-months (BCVA [r = -0.413, p = 0.023], MV [r = 0.482, p = 0.008]). The change in VEGF concentration following ranibizumab treatment did not correlate with either BCVA or MV improvements (p > 0.05).

CONCLUSIONS

Higher levels of aqueous TNF-α and IL-7 correlated with worse DMO, both anatomically and functionally. Reductions in levels of aqueous TNF-α, but not VEGF, post ranibizumab treatment were associated with improvement in BCVA and MV.

Characteristics and outcomes of full-thickness macular holes created during vitrectomy for proliferative diabetic retinopathy

PURPOSE

To investigate the clinical features, management, and prognosis of full-thickness macular holes (FTMHs) inadvertently created during vitrectomy for eyes with proliferative diabetic retinopathy (PDR) and fibrovascular proliferation (FVP).

METHODS

Eyes with PDR and FVP that had intraoperatively created FTMHs were retrospectively collected as the study group, and age- and sex-matched subjects with PDR and FVP who did not have intraoperative FTMHs were selected as the control group. Fundus abnormalities, optical coherence tomography (OCT) features, and anatomical and functional outcomes were compared between the two groups.

RESULTS

Eleven eyes of 11 patients (5 male and 6 female) were identified as the study group. Follow-up duration was 36.8 ± 47.2 months. FTMHs were managed by ILM peeling or the inverted ILM flap technique. Anatomical success and MH closure were achieved in 100% of eyes in the study group. In comparison to the control group, the study group had a higher proportion of condensed prefoveal tissue (63.6% vs. 22.7%, p = 0.028), and a higher ratio of silicone oil tamponade (63.6% vs. 18.2%, p = 0.014), whereas there were no differences in preoperative and final BCVA, and the severity, activity, and locations of FVP between the two groups.

CONCLUSION

Condensed prefoveal tissue was a risk factor of FTMHs created during operation for eyes with PDR and FVP. The ILM peeling or the inverted ILM flap technique may be beneficial for the treatment with favorable anatomical and functional outcomes.

Full-thickness macular hole formation in proliferative diabetic retinopathy

Twenty-one consecutive patients (21 eyes) having proliferative diabetic retinopathy (PDR) and fibrovascular proliferation (FVP) with optical coherence tomography (OCT) available before and after full-thickness macular hole (FTMH) formation were retrospectively reviewed. Four types of FTMH formation pathways in PDR were identified and were quite different from those in idiopathic conditions. The activity, severity and locations of FVP varied in PDR eyes destined to develop FTMHs. Type 1 was characterized by epiretinal membrane (ERM) and/or vitreomacular traction (VMT) inducing foveoschisis, intraretinal cysts or foveal detachment, followed by formation of a FTMH or macular hole retinal detachment (MHRD). In type 2, ERM and/or FVP induced lamellar macular hole (LMH) with foveoschisis, followed by the formation of FTMH or MHRD. Type 3 was characterized by the initial tractional retinal detachment (TRD) with foveal cysts and/or foveoschisis and the subsequent formation of MHRD. Type 4 was characterized by TRD associated with foveal thinning, ensued by the formation of MHRD. The severity of FVP was grade 2 in 66.7% of eyes in both types 1 and 4, and grade 3 in 75% of eyes in type 3 while the severity of FVP was more evenly distributed in type 2.

Ocular expression of cyclin-dependent kinase 5 in patients with proliferative diabetic retinopathy

Aims/Introduction

Inhibition of peroxisome proliferator‐activated receptor gamma (PPARγ) phosphorylation mediated by cyclin‐dependent kinase 5 (Cdk5) is one of the main mechanisms of action of antidiabetic drugs. In this study, we analyzed the ocular expression and activation of Cdk5 in patients with proliferative diabetic retinopathy (PDR).

Materials and Methods

The concentrations of PPARγ, Cdk5 and its activating subunit (p35) were determined in the vitreous body of 24 PDR and 63 control eyes by enzyme‐linked immunosorbent assay. In addition, the messenger ribonucleic acid and protein expression levels of PPARγ, Cdk5 and p35 were measured in proliferative neovascular membranes from seven PDR eyes and non‐neovascular epiretinal membranes from five control eyes by quantitative real‐time polymerase chain reaction and immunohistochemical analysis.

Results

PPARγ, Cdk5 and p35 concentrations in the vitreous body were significantly higher in the PDR group compared with the control group. There was also a positive significant correlation of Cdk5 with PPARγ and p35 in the PDR group. Furthermore, the messenger ribonucleic acid expression levels of PPARγ, Cdk5 and p35 in proliferative neovascular membranes were significantly higher in the PDR group compared with the control group. Immunostaining showed increased protein expression levels of PPARγ, Cdk5 and p35 in proliferative neovascular membranes in the PDR group compared with the control group.

Conclusions

Cdk5 activation is involved in PDR pathogenesis through PPARγ expression, and inhibition of Cdk5‐mediated PPARγ phosphorylation might be a new therapeutic target for treatment of PDR.

The potent small molecule integrin antagonist THR-687 is a promising next-generation therapy for retinal vascular disorders

Integrins are associated with various eye diseases such as diabetic retinopathy (DR) and wet age-related macular degeneration (AMD) and implicated in main pathologic disease hallmarks like neovascularization, inflammation, fibrosis and vascular leakage. Targeting integrins has the potential to attenuate these vision-threatening processes, independent of anti-vascular endothelial growth factor (VEGF) responsiveness. The current investigation characterized THR-687 as a novel pan RGD (arginylglycylaspartic acid) integrin receptor antagonist able to compete for binding with the natural ligand with nanomolar potency (e.g. α_vβ₃ (IC₅₀ of 4.4 ± 2.7 nM), α_vβ₅ (IC₅₀ of 1.3 ± 0.5 nM) and α₅β₁ (IC₅₀ of 6.8 ± 3.2 nM)). THR-687 prevented the migration of human umbilical vein endothelial cells (HUVECs) into a cell-free area (IC₅₀ of 258 ± 113 nM) as well as vessel sprouting in an ex vivo mouse choroidal explant model (IC₅₀ of 236 ± 173 nM), and was able to induce the regression of pre-existing vascular sprouts. Moreover, combined intravitreal and intraperitoneal administration of THR-687 potently inhibited VEGF-induced leakage in the mouse retina. In addition, THR-687 injected intravitreally at 3 different dose levels (0.45 mg, 2.25 mg or 4.5 mg/eye) potently inhibited neovascularization-induced leakage in the cynomolgus laser-induced choroidal neovascularization (CNV) model. These data suggest that THR-687 is a promising drug candidate for the treatment of vision-threatening retinal vascular eye diseases such as DR and wet AMD.

The immunological basis of degenerative diseases of the eye

It has become clear that disorders that were once considered "degenerative" have complex mechanisms, with many having been shown to have immune mediation as part of the disease process. These include arteriosclerotic heart disease and Alzheimer's disease. Indeed, several ocular disorders that once fell into the "degenerative" category meet this criterion as well. Immune mediation has been shown to be a part of many of the most common ocular disorders, and not just that of uveitis, or ocular inflammatory disease.

Role of inflammation in the pathogenesis of diabetic retinopathy

Diabetic retinopathy (DR) remains a major cause of worldwide preventable blindness. The microvasculature of the retina responds to hyperglycemia through a number of biochemical changes, including activation of protein kinase C, increased advanced glycation end products formation, polyol pathway, and oxidative stress, and activation of the renin angiotensin system (RAS). There is an accumulating body of evidence that inflammation plays a prominent role in the pathogenesis of DR.