Expression of Angiogenic MicroRNAs in Endothelial Progenitor Cells From Type 1 Diabetic Patients With and Without Diabetic Retinopathy

PURPOSE

MicroRNA (miR) expression in endothelial progenitor cells (EPCs) in type 1 diabetes (DM1) and its relation with different stages of diabetic retinopathy (DR) have not been reported to date. Our aim was to analyze miR-222, miR-221, and miR-126 expression in EPCs from DM1 patients with and without DR.

METHODS

We included 41 patients with DR, 35 without DR, and 38 controls. Blood was collected for flow cytometry and EPC culture. Total RNA was extracted and purified and real-time quantitative PCR was performed for miR expression in cultured EPCs. Relative changes in miR expression were analyzed with the 2-ΔΔCT method.

RESULTS

Circulating EPCs were reduced and miR-126 expression was increased in DM1 compared to controls (0.030 [interquartile range [IQR], 0.020-0.050] vs. 0.060 [IQR, 0.030-0.110], P = 0.004; 1.740 [IQR, 0.890-4.120] vs. 0.990 [IQR, 0.487-3.015], P = 0.047 respectively) without differences between patients with and without DR. Patients with DR had higher expression of miR-221 than those without DR (1.405 [IQR, 0.820-2.867] vs. 0.915 [IQR, 0.507-1.292], P = 0.019) without differences among degrees of DR. Circulating EPCs were reduced in patients on statins (0.010 [IQR, 0.010-0.050] vs. 0.045 [IQR, 0.020-0.087], P = 0.008), and miR-221 expression increased in patients on angiotensin-converting enzyme (ACE) inhibitors/angiotensin receptor blocker (ARB) II (1.430 [IQR, 1.160-2.705] vs. 1.000 [IQR, 0.520-1.330], P = 0.021) compared to those without treatment. MicroRNA-126 expression was associated with body mass index (BMI; ρ = -0.267, P = 0.026) and diastolic blood pressure (ρ = -0.267, P = 0.034). MicroRNA-221 was associated with triglyceride concentration (ρ = 0.296, P = 0.012).

CONCLUSIONS

Circulating EPCs were reduced and miR-126 expression was increased in DM1 compared to controls. Patients with DR had higher expression of miR-221 than those without DR. The identification of biomarkers of diabetic complications might be useful for monitoring disease progression and potential therapeutic targets.

Modelling postoperative visual acuity with and without proliferative vitreoretinopathy associated with primary rhegmatogenous retinal detachment

PURPOSE

To find models that will explain the variability in postoperative visual acuity (VA) (logarithmic: logMAR) associated with unilateral primary rhegmatogenous retinal detachment (RD).

METHODS

This was a prospective clinical cohort study of 33 patients with proliferative vitreoretinopathy (PVR: PVR<C3) and 33 without PVR, all of whom were candidates for scleral buckling (SB) surgery. Central retinal artery (CRA) Doppler sonography parameters (peak systolic, end diastolic velocities and resistibility index) and intraocular pressure (IOP) were measured before SB. Immunoreactive endothelin-1 (IR-ET-1) levels in both plasma and subretinal fluid (SRF) were measured using a radioimmunoassay. Visual outcomes were analysed by stepwise multivariate linear regression. The preoperative parameters used in the analysis included RD duration, IOP, logMAR VA, CRA parameters, preoperative plasma levels and intraoperative levels of IR-ET-1 in the SRF.

RESULTS

The models for 8-month-postoperative logMAR VA demonstrated a predictive power higher than 85%. The values of the 8-month-postoperative logMAR VA were as follows: (a) in No PVR= -0.151+0.06 preoperative duration (days), with a predictive power of 85.3%; (b) in PVR= -1.071+0.06 SRF IR-ET-1 (pg/ml)+0.459 preoperative logMAR VA explaining 89.9% of the variability in the postoperative logMAR VA.

CONCLUSIONS

The duration of RD and the levels of IR-ET-1 in the SRF appear to be the best explanatory variables in the models for 8-month-postoperative logMAR VA variability in RD patients. RD surgery should be performed as soon as possible to best preserve VA.

Preoperative duration of retinal detachment and preoperative central retinal artery hemodynamics: repercussion on visual acuity

PURPOSE

To analyze if preoperative duration of primary rhegmatogenous retinal detachment (RD) influences preoperative central retinal artery (CRA) hemodynamics with repercussions on logarithmic (LogMAR) visual acuity (VA).

METHODS

Prospective clinical cohort study on 66 healthy patients (33 with proliferative vitreoretinopathy (PVR) and 33 with no PVR) with unilateral RD candidates for scleral buckling (SB) surgery (PVR <C3) as a first and single surgical procedure. CRA Doppler sonography parameters (peak systolic, end diastolic velocities and resistibility index) and IOP were measured before SB. Pearson's correlations were evaluated between preoperative RD duration and each preoperative CRA parameter, and also between both variables and the LogMAR VAs (preoperative, postoperative 8 months, and the difference: postoperative 8 months minus preoperative).

RESULTS

Preoperative duration of RD was correlated (with statistical significance both PVR and no PVR) with pre- and postoperative 8 months LogMAR VAs (both positive correlations), with preoperative IOP (negative correlation), and with preoperative CRA parameters (negative correlations with CRA velocities and positive correlation with resistibility index). Preoperative CRA parameters (correlated with preoperative IOP in PVR) were correlated (negatively for CRA velocities and positively for CRA RI) with LogMAR VAs (preoperative, postoperative 8 months, and difference) in PVR. The average preoperative RD duration was longer in the PVR group than in the no PVR group (p < 0.0001). A longer preoperative RD duration was associated with macula-off in both groups. Macula-off and PVR respectively showed lower preoperative IOP and lower preoperative CRA velocities than macula-on and no PVR.

CONCLUSIONS

Preoperative CRA parameters and LogMAR VAs (pre-, and postoperative 8 months) were influenced by preoperative RD duration in both no PVR and PVR. Preoperative CRA parameters were correlated with LogMAR VAs (pre-, postoperative 8 months, and the difference) only in PVR. Postoperative 8 months and preoperative LogMAR VAs were only correlated (with statistical significance) in macula-on cases of both the PVR and no PVR groups.

MIRAgel

OBJECTIVE

To analyze long-term complications of hydrogel (MIRAgel; MIRA Inc, Waltham, Mass) explants.

DESIGN

Institutional clinical study of a retrospective, interventional case series of patients. We included 415 patients with complete reattachment of the retina 6 months after surgery and up-to-date follow-up. Patients underwent ophthalmological examination at each visit (mean follow-up, 187 months), and 6 underwent computed tomography and/or magnetic resonance imaging. Main outcome measures included the MIRAgel explant removal rate, clinical manifestations related to removal, interval from the start of discomfort to removal, mean time from implantation to removal, culture yield of the removed elements, results of histological examination of the capsule surrounding the removed explants (12 cases), and micro-Fourier transform infrared spectroscopic analysis results of 3 recovered explants.

RESULTS

MIRAgel explant removal was necessary in 27 (6.5%) of 415 patients who received MIRAgel material and in 27 (7.6%) of 357 patients who had had it for 7 or more years. Clinical manifestations were related to swelling of the MIRAgel material, with a mean interval of 15 (range, 6-22) months from starting symptoms to removal. The infrared spectroscopic analysis demonstrated the presence of carboxylic groups in 3 recovered explants that had swollen considerably.

CONCLUSION

Prompt removal of MIRAgel explants when discomfort starts should be considered to avoid increased incidence of complications.

IMMUNOREACTIVE ENDOTHELIN-1 IN THE VITREOUS HUMOR AND EPIRETINAL MEMBRANES OF PATIENTS WITH PROLIFERATIVE DIABETIC RETINOPATHY

PURPOSE

To investigate the potential role of endothelin-1 (ET-1), a potent vasoconstrictor with mitogenic properties, in the pathogenesis of proliferative diabetic retinopathy (PDR).

METHODS

Plasma and vitreous samples were collected from normal patients (controls; n = 25), diabetic patients with PDR (n = 25), and diabetic patients with non-PDR (n = 25). The patients had to have epiretinal membranes (ERMs) or other ocular conditions that made them candidates for vitrectomy. Immunoreactive ET-1 (IR-ET-1) was assayed in plasma and vitreous samples by radioimmunoassay. IR-ET-1 was immunohistochemically localized in ERMs. Expression of endothelin receptors A (ETA) and B (ETB) was confirmed by reverse transcription-polymerase chain reaction analysis.

RESULTS

IR-ET-1 levels in plasma and vitreous samples from diabetic patients were higher (P < 0.0001) than those in samples from the control group. The levels for patients with PDR were even higher (P < 0.0001) than those for patients with non-PDR. Eyes with ERMs in the PDR group had the highest vitreous IR-ET-1 levels (14.67 +/- 0.67 pg/mL). IR-ET-1 was localized in the cellular and stromal components of ERMs in diabetic and nondiabetic patients. Furthermore, the ETA and ETB receptors were expressed in both diabetic and nondiabetic ERMs.

CONCLUSIONS

Diabetic patients with PDR and ERMs had the highest plasma and vitreous IR-ET-1 levels. ET-1 and its ETA and ETB receptors were present in ERMs. These data suggest that ET-1 is involved in diabetic vitreoretinal disease.

Immunoreactive ET-1 in the vitreous humor and epiretinal membranes of patients with proliferative vitreoretinopathy

PURPOSE

Endothelin one (ET-1) is a vasomodulator peptide that plays a role on ocular blood flow, glial proliferation, and collagen matrix contraction by retinal pigmented epithelial (RPE) cells. Both glial and RPE cells have been involved in the formation of epiretinal membranes (ERMs). This investigation was conducted to determine whether ET-1 may be associated with ERMs, either idiopathic (IERMs) or from proliferative vitreoretinopathy (PVR).

METHODS

Plasma and vitreous samples were collected from patients classified by the presence of PVR membranes, retinal detachment (RD), and other ocular conditions, such as IERMs, that made the patients candidates for vitrectomy. Immunoreactive endothelin one (IR-ET-1) was tested in plasma and vitreous by radioimmunoassay. Immunoreactive-ET-1 was localized in IERMs and PVR membranes immunohistochemically. Expression of endothelin receptors A (ETA) and B (ETB) was confirmed by reverse transcription-polymerase chain reaction.

RESULTS

IR-ET-1 levels in plasma and vitreous were higher in patients with PVR and in patients with RD than in those of the control group. Eyes with IERMs also showed higher IR-ET-1 levels than the control group cases. IR-ET-1 levels in eyes with PVR were higher than those in eyes with IERMs. IR-ET-1 levels in eyes with RD were also higher than those of eyes with IERMs. Immunoreactive ET-1 was localized in the cellular and stromal components of both IERMs and PVR membranes. Furthermore, ETA and ETB receptors were expressed in both IERMs and PVR membranes.

CONCLUSIONS

IR-ET-1 in human vitreous is elevated in PVR, RD, and IERMs. ET-1 and its receptors ETA and ETB are present in epiretinal tissue of both idiopathic and PVR membranes. These data suggest an involvement of ET-1 in retinal disease.

Atrial natriuretic peptide in the vitreous humor and epiretinal membranes of patients with proliferative diabetic retinopathy

PURPOSE

Atrial natriuretic peptide (ANP) has been recently described as an endogenous inhibitor of the synthesis and angiogenic action of vascular endothelial growth factor (VEGF). Given VEGF's key role in promoting neovascularization in proliferative diabetic retinopathy (PDR), this study was designed to evaluate the possibility that ANP could be involved in the neovascular and fibrotic complications of PDR.

METHODS

We determined ANP by radioimmunoassay in plasma and vitreous humor samples collected from diabetic patients with and without PDR and from non-diabetic subjects. ANP was also immunohistochemically localized in the epiretinal membranes of patients with PDR.

RESULTS

Vitreous ANP concentrations were significantly higher in patients with active PDR compared to patients with quiescent PDR, diabetes without PDR or controls <0.05. Significant differences were also observed between vitreous ANP levels in diabetic patients without PDR and control subjects. There was no significant correlation between serum and vitreous ANP levels in any of the patient groups. ANP was detected in the fibrovascular epiretinal tissue of patients with PDR.

CONCLUSIONS

Diabetic patients with active neovascularization have significantly higher levels of ANP in the vitreous humor than those without active PDR. Diabetic patients without PDR were also found to have significantly higher vitreous ANP levels than non-diabetic patients. Since plasma and vitreous ANP concentrations were found to be unrelated, we suggest intraocular ANP synthesis and/or an increase in the release of ANP into the vitreous, as opposed to diffusion from the blood, as the main factors contributing to the high vitreous ANP levels observed in diabetic patients. In the fibrovascular epiretinal tissue of these patients, ANP was found to be localized in vascular, glial, fibroblast-like and retinal pigment epithelium cells. Our findings suggest a role for ANP in PDR.

Natriuretic peptide system in the human retina

PURPOSE

The natriuretic peptide (NP) family includes atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP). Natriuretic peptides are known to inhibit vascular cell growth and regulate vessel tone. There is also much evidence to suggest they modulate vascular permeability and angiogenesis, as well as regulating aqueous humor production in the eye. All these data indicate that the natriuretic peptide system might be involved in the development of diabetic retinopathy and glaucoma. Given the expression pattern of natriuretic peptides (NPs) and their receptors, natriuretic peptide receptor A (NPRA), natriuretic peptide receptor B (NPRB) and natriuretic peptide receptor C (NPRC) in the human retina has not yet been established, the present study was designed to determine ANP, BNP and CNP gene expression and localize the mature peptides in this tissue. The expression pattern of the genes encoding the different NP receptor subtypes was also examined.

METHODS

Eyes (n=10) from human donors with no history of eye disease were fixed and processed for routine paraffin embedding. The cellular location of the NPs was established by immunohistochemistry. Real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to evaluate the expression of NP and NP receptor genes in neural retinas obtained from the contralateral eyes.

RESULTS

Immunohistochemistry revealed the presence of NPs in the neural retina and retinal pigment epithelium. Positive NP immunostaining was observed within the astrocytes and in their processes enveloping vessels. In the anterior portion of the optic nerve, NPs were intensely labeled in neural bundles. We were able to detect NP gene expression in the human retina. The levels of NP receptor-encoding transcripts detected indicated no significant differential expression of genes coding for the different receptor subtypes.

CONCLUSIONS

Our finding that NP receptor transcripts are expressed along with ANP, BNP, and CNP mRNA in the human retina provides evidence for a local system in this tissue. The expression of NPs in neural retinal, glial, and vascular elements of the normal adult retina suggests a role for these peptides in maintaining both the neural and vascular integrity of the mature retina.

Localisation of endothelin-1 mRNA expression and immunoreactivity in the retina and optic nerve from human and porcine eye. Evidence for endothelin-1 expression in astrocytes

We have investigated the localisation of endothelin-1 (ET-1) mRNA and ET-1-like immunoreactivity in retina and anterior portion of optic nerve from human and porcine eyes. In situ hybridisation method revealed expression of ET-1 mRNA mainly in the innermost layers of the retinas, in the retinal pigment epithelium cells as well as in the astrocytes of the optic nerve. Immunohistochemical studies showed that ET-1-like immunoreactivity appeared in the same regions where ET-1 mRNA was expressed as well as in the inner nuclear layer and in the inner segments of photoreceptors. In the nerve fibre and ganglion cell layers, astrocytes expressed both glial fibrillary acidic protein and ET-1 proteins suggesting that these cells may secrete ET-1. Expression of ETA and ETB receptors in human retina were demonstrated by reverse transcription-polymerase chain reaction. Our results demonstrated expression of ET-1 in glial, neural and vascular components of retina and optic nerve from human and porcine eyes.

Laser interferometry: preoperative functional predictive value in retinal detachment

PURPOSE

To determine the functional predictive value of laser interferometry (LI) in retinal detachment (RD).

METHODS

Laser interferometry with test field diameters of 3 degrees and 8 degrees, both with and without light, was tested preoperatively in 42 eyes with rhegmatogenous RD that were candidates for scleral buckling. Snellen visual acuity (VA) and LI (four test fields) were tested preoperatively and postoperatively (1 week, and 1, 3, and 7 months). Sensitivity and specificity of LI to predict postoperative (7 months after surgery) VA improvement was calculated. Chi-square and Spearman correlation tests were used for statistical analysis.

RESULTS

Statistically significant Snellen VA improvement (P = 0.02) was first found 7 months after surgery. Laser interferometry at 3 degrees without light showed statistically significant improvement 3 months after surgery (P = 0.05). Laser interferometry at 3 degrees without light showed the highest sensitivity (93%) and specificity (87%) values. The best correlation between preoperative LI and postoperative Snellen VA (7 months after surgery) was also found with 3 degrees LI without light (r = 0.71, P = 0.002).

CONCLUSION

Laser interferometry (3 degrees without light) was useful in predicting VA improvement in cases with RD preoperatively and postoperatively. Laser interferometry at 3 degrees without light showed the best correlation with postoperative Snellen VA.

Long-term complications of silicone and hydrogel explants in retinal reattachment surgery

OBJECTIVE

To compare long-term complications of silicone sponge, silicone rubber, and MIRAgel used as episcleral buckling elements.

METHODS

Medical reports were reviewed of 805 patients with cryotherapy and episcleral buckle for rhegmatogenous retinal detachment who were operated on by 1 of us (M.R.-P.) between March 1984 and December 1997. Average follow-up was 76 months. Symptoms and signs of infection or rejection were considered. Care was taken in buckling element removal, considering the material used for scleral buckling (detailed operative note), duration of the buckle, cause of removal, and culture of the removed element.

RESULTS

A total of 757 patients were included in the study. Removal of the implant was necessary in 10 patients (1.3%). Silicone sponge (3 [9%] of 32 patients) was more frequently removed than was silicone rubber (2 [0.6%] of 360 patients) or MIRAgel (5 [1.3%] of 386 patients). Silicone sponge needed to be removed a short time after surgery, showing symptoms of acute infection and positive cultures. Silicone rubber was removed 1 year after surgery with symptoms of chronic infection and positive cultures, and MIRAgel implants were removed after long-term follow-up (7-10 years), showing positive cultures in only 20%.

CONCLUSION

Periodic long-term follow-up previously recommended for use of other materials also must be recommended for MIRAgel use because of long-term alterations in its chemical composition and eventual swelling of material.