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Chang He, Yuying Sun, Xiao Hu, Jing Wang, Lu Wang, Yizhi Liu, Xialin Liu; The imbalance of Th17 and Treg cells in the retinopathy of diabetic rat model. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2697. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
The balance between pro-inflammatory Th17 and anti-inflammatory regulatory T cell (Treg) is recently reported to be crucial for immune homeostasis. Diabetic retinopathy is regarded as a chronic inflammatory disorder with changes in immune cell function. The purpose of this study is to investigate the profile of Th17 cells and Tregs including their key transcription factors and related cytokine secretion in vascular leakage in retinal tissue of diabetic rat models.
Sprague Dawley rats were injected intraperitoneal Streptozotocin (STZ) to induce hyperglycemia and diabetic retinopathy. Blood glucose and body weight were monitored. At three months after induction, retinal vascular permeability was measured in vivo by the Evans Blue dye method. Flow cytometry was used to evaluate the frequencies of IL-17-producing T cells and CD4+CD25+Foxp3+ Tregs in spleen and periphery blood. In addition, mRNA levels of ROR-γt and Foxp3 (transcription factors of Th17 and Treg cells, respectively) in retinas are quantified using real-time quantitative PCR. Levels of cytokines produced by Th17 and Treg cells (IL-17 and TGF-β) and VEGF are measured by real-time quantitative PCR, Western blot and immunofluorescence.
At three months after STZ treatment, STZ-treated diabetic rats demonstrated significant blood-retinal barrier (BRB) leakage and increased VEGF level compared with non-diabetic control rats. Th17 cells related transcription factor (ROR-γt) was activated and expression of its associated cytokine (IL-17) increased in the diabetic retinas with respect to non-diabetic control. The proportion of IL-17 and TGF-β was significantly elevated, suggesting the imbalance between Th17 cells and Tregs may exist in the diabetic retinas. In addition, the bias of Th17/Treg was strongly correlated to VEGF level in diabetic retinas.
Our results indicated that a loss of immune-balance of Th17 to Treg may have a critical role in vascular leakage and further shed new light into understanding the immune-inflammatory mechanism of diabetic retinopathy.
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