Abstract
Purpose :
Leukostasis is a critical early step that has been shown to play an important role in the development of diabetic retinopathy (DR). The inflammatory cells, once adhered, release factors that further amplify the inflammatory milieu. Our previous results examining the influence of inflammation and glycation in the transcriptome profile and molecular signaling pathways of human retinal endothelial cells (HREC) revealed that CXCL5 genes were significantly up-regulated in advanced glycation end product-treated cells relative to their normal counterparts. Here we examined CXCL6, a paralog of CXCL5, in an in vivo mouse model to determine its contribution to the disruption of tight-junction in retinal vessels associated with DR.
Methods :
Recombinant CXCL6 (100 ng/eye) or sterile water (vehicle) was injected intraocularly into C57bl/6 mice (n=5) followed by FACS analysis of immune cell infiltration. Next, qPCR analysis was used to determine mRNA expression of key proteases and chemokines. Western Blot analysis was used to evaluate the expression of albumin and VE-cadherin.
Results :
Recombinant CXCL6 intravitreal injection caused significant recruitment of inflammatory cells, as judged by a >15-fold increase in neutrophils, a 3-fold increase in monocytes, and a 2-fold increase in macrophages. Importantly, qPCR analysis revealed increased expression of CCL2 (5-fold), MMP12 (7-fold) and Cathepsin B and Cathepsin S (2-fold ) mRNA expression. Our Western Blot analysis confirmed that CXCL6 causes a significant increase in permeability, which correlates with increased albumin and decreased VE-cadherin expression.
Conclusions :
Our findings thus far reveal a potentially crucial role of CXCL6 in vascular dependent retinal inflammation associated with DR and provide rationale to further examine this pathway for the identification of novel anti-inflammatory targets for improved DR therapies in the future.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.