Abstract
Purpose :
Proliferative vitreoretinopathy (PVR) is an inflammatory and fibrotic disease. Interleukin-6 (IL-6) is an inflammatory cytokine known to be elevated in subretinal fluid in patients with proliferative vitreoretinopathy (PVR). We investigated the effects of IL-6 on proliferation and epithelial-mesenchymal transition (EMT) in retinal pigment epithelium (RPE) cells and in mouse PVR models.
Methods :
When treated with various concentrations of IL-6, RPE cells proliferation was assessed by CCK-8 assay and EdU staining, and EMT markers were evaluated with western blot and immunofluorescent staining. The activation of JAK/STAT3 signaling was determined with western blot. Moreover, the effect of blockade of IL-6/JAK/STAT3 signaling was also investigated using pharmacological inhibitor S3I-201. To test the hypothesis that IL-6 elevation is involved in PVR development in vivo and depletion of IL-6 will inhibit PVR progression, we injected collagenase/dispase into the vitreous to induce PVR in the wild-type (WT) and IL-6 knockout (KO) mice. The expressions of IL-6, gp130, and EMT markers were assessed using real-time PCR. and the severity of PVR was evaluated by histological analysis.
Results :
Treatment with IL-6 increased RPE proliferation in a dose-dependent manner. The results from western blot and immunofluorescent staining assays showed treatment with 10 and 25 ng/ml of IL-6 significantly induced RPE EMT in vitro. Additionally, IL-6 treatment could rapidly activate JAK1 and STAT3 by phosphorylation in the RPE cells. Blockade of IL-6/JAK/STAT3 signaling with S3I-201 effectively inhibited RPE proliferation and EMT. Furthermore, IL-6 expression was dramatically increased in the WT mice at 1 and 3 days following collagenase/dispase injection, but not in the IL-6 KO mice. Finally, we confirmed that IL-6 deletion decreased EMT markers expression and inhibit PVR progression in the IL-6 KO mice compared to the WT mice by performing real-time PCR and histological analysis.
Conclusions :
Taken together, the findings indicate that IL-6 promotes PVR by inducing RPE cells EMT via the JAK/STAT3 signaling pathway. This study provides new evidence that therapeutic strategies to block IL-6 may be beneficial for PVR.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.