First Author: J.Estudillo MEXICO
Co Author(s): J. Palomares Ordonez A. Robles Contreras
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Is well known that proliferative vitreoretinopathy (PVR) is one of the main causes of therapeutic failure in rhegmatogenous retinal detachment (RRD). PVR consists of an epithelial-mesenchymal transition, which involves a process of dedifferentiation of specialized tissue, proliferating to form fibrotic tissue. The transforming growth factor beta (TGFβ), stands out in the pathophysiology of PVR. We determined the concentrations of TGFβ1 in vitreous of patients with PVR, secondary to RRD to demonstrate if there is a correlation with the degree of clinical severity.
There were included patients with a diagnosis of rhegmatogenous retinal detachment (RRD), attended during the period from August 2015 to June 2016 at “Fundación Hospital Nuestra Señora de la Luz”, a national reference centre for ophthalmologic care in Mexico City, Mexico.
This is an observational, cross-sectional and comparative study. We included forty patients undergoing pars plana vitrectomy (PPV) for DRR, with different degrees of PVR. There were excluded all patients previously vitrectomized, or those who had antecedent of had been undergone any other surgery or who presented with any other ophthalmological condition. We standardized the procedure, which consisted in obtained the sample by extracting 0.3ml of concentrated clear vitreous, prior to the opening of the infusion.The vitreous of these patients was kept in ultra-freezing at -80° immediately after their extraction until analysis. TGFβ1 levels were quantified by ELISA technique (R&D Systems, Minneapolis USA), following the methodology proposed by the supplier. For the analysis, patients were divided according to the PVR classification, proposed by the silicone oil Study Group. Once the values were determined, a D'Agostino-Pearson test was performed for the evaluation of the distribution and a 1 way-ANOVA test was then performed for the comparison of the different groups together with a Dunns post-hoc test. A statistically significant difference was considered when a P<0.05 was obtained.
A total of 40 eyes from 39 patients were included, they were classified into 3 groups according PVR scale mentioned before, corresponding to grade A, B, or any category of C. Levels of TGFβ1 were quantified and the following means were reported for each group. In group A, 1150.6 pg / ml + 452.08 n = 10. In group B, 1129.6 + 365.54 n = 10. In group C, 1146.4 + 330.21 n = 20. Statistical analysis reports non-significant differences when comparing the different PVR groups (P = 0.5390). Another analysis was made considering time since the patient reported the visual loss until the procedure, where a tendency to present higher levels of TGFβ1 in the vitreous of those patients with a longer time of evolution of the RRD, the statistical analysis did not report significant differences (P = 0.5390). However, when performing the differential analysis for each degree of severity, a statistically significant increase in the expression of TGFβ1 was observed in the group of patients with PVR-A at a greater number of days of evolution of the detachment. (P = 0.03). Differences that were not statistically significant for PVR-B and C. (P = 0.1631), (P = 0.1665).
Significant amounts of TGFβ1 were founded in each group, with a tendency to increase according to the progression of PVR, without demonstrating a statistically significant difference, so it is assumed that there is no direct correlation between the concentrations of this factor with the clinical severity score. The levels of TGFβ1 had a direct relationship with the time of evolution in patients with PVR-A, which coincides with the theory that it is more relevant during the initial stages of the clinical course. Previous reports show that inhibition of TGFβ1 had a greater effect than the inhibition of TGFβ2 in recruiting macrophages and the subsequent induction of the epithelial-mesenchymal transition in healing models. Although TGFβ1 is not directly related to clinical severity, it may be one of the main factors involved in promoting the epithelial-mesenchymal transition due to its greater expression in the initial stages. From which it can be concluded that each isoform plays a very particular role in the complex process of PVR.