Interleukin 17 (IL-17) and IL-17 Receptors in the Murine and Human Diabetic Retina

Abstract

Purpose: : Interleukin 17 (IL-17), a product of Th17 lymphocytes, has been shown to play a critical role in chronic inflammatory diseases. We have previously shown that circulating (serum) levels of IL-17 are increased in diabetic patients presenting signs of retinopathy. Here we further studied the expression pattern of IL-17 and its receptors (IL17Rs) in the murine and human (post-mortem) diabetic retina.

Methods: : Immuno-histochemical and ELISA analyses were conducted to determine the expression pattern of IL17Rs and IL-17 (respectively) in the retinal tissue obtained from streptozotocin-induced diabetic mice (STZ-mouse), after 8 weeks of hyperglycemia, and from human post-mortem retinas of diabetic donors. Age-matched normoglycemic mice retinas and human post-mortem retinas from non-diabetic donors were used as normal controls.

Results: : IL-17 protein levels were increased in both the murine and human diabetic retinas as compared to age-matched normoglycemic murine retinas and human non diabetic donors. IL-17Rs were also up-regulated in both murine and human retinas as compared to normoglycemic controls. Of interest, IL-17Rs were immunolocalized in the retinal ganglion cell layer, especially at the vitreoretinal interface.

Conclusions: : The results further support the potential role of IL-17 in the pathogenesis of diabetic retinopathy and also identify the vitreoretinal surface as a possible site of action of IL-17 in the diabetic retina.

Keywords: diabetic retinopathy • inflammation • immunomodulation/immunoregulation