Abstract
Purpose: :
To investigate human Bruch’s membrane proteome alterations in diabetic retinopathy.
Methods: :
Human Bruch’s membrane explants were prepared from six eyes from young (<55) donors suffering from insulin-dependent diabetes with non-proliferative diabetic retinopathy. Globes were processed within 24 hours of death. An excimer laser was used to ablate the choroid leaving only pure human Bruch’s membrane explants. Bruch’s membrane proteins were then extracted and analyzed with electrospray ionization-quadruple time-of-flight MS/MS (ESI-Q-TOF MS/MS). Results were compared with Bruch’s membrane proteomes of six eyes obtained from non-diabetic age-matched controls. Ingenuity pathway analyses were conducted to map the pathogenic mechanisms.
Results: :
225 proteins were identified in non-diabetic control Bruch’s membranes. The Bruch’s membrane proteome of diabetic eyes revealed 125 proteins of which 23 were exclusively expressed in diabetes (p<0.05). Common protein pool included mainly extracellular matrix proteins, such as collagen, actin, vimentin, and tubulin. In diabetic donors 88 proteins were significantly decreased from the normal Bruch’s membrane proteome, whereas 23 new proteins appeared. Pathway analysis indicated deposition of acute phase response, IL-17 signaling, LXR/RXR signaling and Reelin signaling pathway proteins in the diabetic Bruch’s membrane(p<0.001). These proteins suggest involvement of immune and coagulation pathways, as well as TNF-alpha/NFkB signaling in the outer retinal cellular pathology in diabetes.
Conclusions: :
Bruch’s membrane proteome changes in diabetes probably reflect pathogenic events occurring within the adjacent retinal cells. Proteome alterations in diabetic retinopathy indicate immune (IL-17, IL-6, CRP) and coagulation (fibrinogen, hemoglobin) pathway involvement in cellular pathologies, as well as activation of TNFalpha and LXR/RXR signaling pathways.
Keywords: diabetic retinopathy • Bruch's membrane • proteomics