Abstract
Purpose: :
Experimental and clinical evidence has suggested that chronic inflammation is involved in the pathogenesis of diabetes complications including diabetic retinopathy (DR). Increased entrapment of immune cells in the retinal microvasculature may significantly contribute to retinal inflammation by locally releasing inflammatory cytokines and, possibly, leading to DR. In this study we investigated the intracellular levels of IL-2, TNF alpha and IFN gamma in lymphocytes and monocytes of diabetic patients presenting or not clinical evidence of DR.
Methods: :
Circulating blood cells were isolated from patients affected by Type 1 (T1DM, n=14) and Type 2 (T2DM, n=23) diabetes mellitus and from age-matched healthy volunteers (NDM, n=14). Flow cytometry analysis assessed intracellular (lymphocytes and monocytes) content of IL-2, IFN gamma and TNF alpha. Fluorescein angiography was performed to assess clinical evidence of retinopathy following standard protocols.
Results: :
IL-2 and IFN gamma were elevated in lymphocytes and monocytes of T1DM and T2DM patients versus NDM (2.5 and 1.5 fold respectively, p<0.05). TNF alpha was elevated only in TD1M (2 fold, p<0.0.5) but not in T2DM. Of interest, in TD1M patients IL-2, TNF alpha and IFN gamma, were elevated prominently in those subjects presenting clinical evidence of DR.
Conclusions: :
The obtained results show that increased content of intracellular cytokines in lymphocytes and monocytes of T1DM patients and, only in lesser extent, of T2DM, correlates with progression of DR. Furthermore, this study suggests that measurements of intracellular cytokines content of circulating blood cells may have diagnostic value for DR.
Keywords: diabetic retinopathy • cytokines/chemokines • inflammation