Abstract
Purpose :
Posterior vitreous detachment and vitrectomy mitigate neovascularization growth in proliferative diabetic retinopathy (PDR). Thus, the vitreous body and vitreous macrophages, called hyalocytes, have been suggested as essential participants in the course of PDR in the past. In this study, the transcriptome of diabetic hyalocytes was assessed to gain further insight into their potential contribution to diabetic vitreoretinal disease.
Methods :
A total of 52 patients treated by vitrectomy for PDR (n = 20), macular pucker or macular hole (n = 32, controls) were included in this study. Hyalocytes were isolated by flow cytometry, followed by RNA extraction. After RNA sequencing, differentially expressed genes (DEG) and enrichment of genes associated with specific biological processes (Gene Ontology, GO) were analyzed bioinformatically. On the protein level, the expression of 54 proteins was compared between the diabetic and control vitreous by multiplex cytokine analysis. Moreover, factors of interest were stained immunohistochemically in cultured human hyalocytes.
Results :
Hyalocytes from PDR patients showed a total of 255 upregulated and 400 downregulated DEG compared to hyalocytes from controls. The transcriptional signature of hyalocytes in PDR was mainly characterized by the enrichment of factors involved in immunological GO processes such as "chemotaxis" (e.g. LGMN, legumain, and EDNRB, endothelin receptor type B) and "leukocyte migration" (e.g., S1PR1, sphingosine-1-phosphatase receptor 1, and MMP9, matrix metallopeptidase 9). In addition, hyalocytes in PDR expressed pro-inflammatory angiogenic factors, e.g. IL6, interleukin 6, which was also significantly increased on the protein level in the diabetic vitreous. Furthermore, enzymes with key functions in hemoglobin catabolism such as HMOX1, heme oxygenase-1, BLVRA, and BLVRB, biliverdin reductases, were among the most prominent factors in diabetic hyalocytes. Finally, cultured diabetic hyalocytes stained positive for CD235, a protein of the human erythrocyte membrane.
Conclusions :
Our analysis offers a first characterization of the hyalocyte transcriptome in patients with PDR and strongly suggests that hyalocytes actively contribute to the pro-inflammatory and angiogenic diabetic vitreous milieu. Moreover, hyalocytes appear to be involved in erythrophagocytosis in the diabetic vitreous, which reveals potential therapeutic venues.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.