Abstract
Purpose: :
Previous immunohistochemical studies revealed that sympathetic ophthalmia (SO) is a CD4+ T cell-mediated intraocular inflammation and tissue damage appears to derive from TNF-α, TNFR1 and iNOS. MicroRNA regulates the target mRNA post-transcriptionally and the downregulation of microRNA results in upregulation of target mRNA and its translation. Recently microRNA expression profiles in paraffin-embedded (FFPE) human pathologic specimens have been shown to be virtually identical to those of fresh tissue. In this study, we used globes with clinical and histopathologic diagnosis to detect the microRNA expression in SO. Retina and choroid were micro-dissected from FFPE sections to use for the analysis.
Methods: :
Two groups of 4 globes each with SO (experimental groups: E1, E2) and one group of 4 age-matched non-inflamed enucleated globes (control group: C1) were used. Human genome-wide microRNA PCR array (Qiagen/SABiosciences) was performed and both sets of results, E1/C1 and E2/C1 were subjected to bioinformatics calculation and p-values stringency tests. The targets were searched by validated and periodically updated miRwalk software.
Results: :
Downregulated 16 microRNAs (miR-1, -9, -30d, -95, -99a, -139-5p, -181a, -181b, -182, -203, -211, -335, -376a, -379, -504 and -551b) were >2-fold change and p-value<0.05 by the student’s t test. From these, 5 microRNAs (miR-1, -9, -181a, -203 and -335) were known to be interrelated and specifically signifying CD4+ T cell-driven adaptive immune response (based on miRwalk). The targets for these 5 microRNAs were CD4+ T cell, TCR, TNF-α, TNFR1, caspase, NFΚB and apoptosis factors.
Conclusions: :
This study of microRNA of SO using FFPE micro-dissected retina and choroid further defined the mechanism of SO development at the microRNA molecular level which targets, particularly, the TNF-α/TNFR1 signaling pathway. This pathway upregulates iNOS,the initiator of mitochondrial oxidative stress that can lead to disturbance in mitochondrial homeostasis and tissue damage. The knowledge gained in this study might also suggest a translational research possibility using synthetic microRNA mimic-based intervention.
Keywords: immunomodulation/immunoregulation • inflammation • uveitis-clinical/animal model