Dysregulation of circulating CD4 + CXCR5 + PD-1+ T cells in diabetic retinopathy

We aimed to determine an association between follicular helper T (Tfh) cells and Bcl-6 and CXCL13 levels and determine the role of Tfh cells, Bcl-6, and CXCL13 serum levels in the pathogenesis of diabetic retinopathy (DR) since Tfh cells have an important role in type 1 diabetes; however, their role in type 2 diabetes-related DR requires exploration.

Blood samples were collected from 24 patients with non-proliferative diabetic retinopathy (NPDR), 20 with proliferative diabetic retinopathy (PDR), and 18 age- and sex-matched healthy volunteers. Flow cytometry detected CD4 + CXCR5 + PD1+ Tfh cells. Serum Bcl-6 and CXCL13 levels were determined using enzyme-linked immunosorbent assay.

CD4 + CXCR5 + PD-1+ Tfh cell percentages in peripheral blood and serum levels of Bcl-6 and CXCL13 in the non-proliferative DR (NPDR) and proliferative DR (PDR) groups' were significantly higher than those in healthy individuals. The proportion of Tfh cells in DR patients' peripheral blood positively correlated with Bcl-6 and CXCL13 serum levels, DR course severity, Fasting blood glucose, glycosylated hemoglobin and body mass index.

The increased circulating Tfh cells, serum Bcl-6 levels, and CXCL13 levels of DR patients with type 2 diabetes suggested that circulating Tfh cells and the germinal center response may have a role in the occurrence and development of DR.