Abstract
Purpose :
Previous studies have demonstrated the contribution of neutrophils to the inflammatory processes characterizing the induction and progression of diabetic microangiopathy and retinopathy (DR). Recent work has shown that different subsets of circulating and tissue infiltrating neutrophils display discrete functions including pro- and anti-inflammatory (N1 and N2 subsets, respectively). Here we investigated the array of neutrophilic subsets in an experimental model of DR.
Methods :
Male albino rats were rendered diabetic by a single injection of streptozotocin (60mg/Kg, ip) (STZ-rats), whereas age-matched controls were injected with vehicle only. After 8 weeks of diabetes the rats were sacrificed and neutrophils were analyzed by flow cytometry in whole blood and bone marrows (femurs). Tissue infiltrating neutrophilic sub-populations were examined in retinal slurry (dispase) by flow cytometry. Flow data were analyzed using the FlowJo software. Cells with phenotypic features of CD45+CD11b+Ly6G+Ly6C-CD206-TNFα+IL6+IFNγ+ were considered N1 whereas N2 were CD45+CD11b+Ly6G+Ly6C-CD206+IL10+TNFα-IL6-/loIFNγ-/lo.
Results :
Flow cytometry studies comparing diabetic and non-diabetic rats revealed a significant increase in N1 versus N2 subset and a consequent decrease in N1/N2 ratio in peripheral blood, but not in bone marrows of diabetic rats. Similarly, N1 cells were the subset predominantly identified in the retinal slurry of diabetic rats, thus accounting for the majority of the retinal tissue infiltrating neutrophilic cells
Conclusions :
In summary, these results unveil for the first time the association of specific subsets of neutrophils (pro-inflammatory N1) with experimental DR, thus lending support to the recent evidence suggesting the importance of the functional sub-specialization of circulating and tissue infiltrating neutrophils in pathological conditions including DR.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.