Effects of lipid-based nanocarriers loaded with a siRNA silencing HuR expression on the retina of diabetic rats

The embryonic lethal abnormal vision (ELAV) RNA-binding proteins family plays a critical role in the life of a messenger RNA, being able to virtually affect any aspect of the post-synthesis fate of the bound transcript. The ELAV family includes the ubiquitously expressed member, HuR, and the neuron-specific members, namely HuB, HuC and HuD. These proteins, along with the nuclear activities, shuttle between the cytoplasm and the nucleus and mainly increase the stability and/or the rate of translation of the target mRNA. Vascular endothelial growth factor (VEGF) is a protein that plays a pivotal role in the angiogenesis and vasculogenesis. Indeed, it influences proliferation, migration, and survival of cells, besides vessel permeability, in various biological contexts. Moreover, it participates in the development of pathologic microvascular complications related to diabetic retinopathy. VEGF content is elevated in the vitreous and aqueous fluids of the eye of patients with diabetic retinopathy, due to the HuR stabilizing effect, having a high binding affinity to specific sequences called AREs (Adenine and uracil-Rich Element) located in the 3ˊUTR (3ˊ-untranslated region) VEGF mRNA preventing its degradation. Considering the role of HuR role in the VEGF overexpression in diabetic retinopathy, our project analyzed the possible therapeutic strategy by targeting specifically HuR in case of diabetic retinopathy. Nanocarriers, solid lipid nanoparticles (SLN) and liposomes (SUV) were loaded with siRNA silencing HuR expression. The nanocarriers were administered in the eye to the diabetic rats (diabetes is induced by streptozotocin (STZ)). Following diabetes indication, the levels of the HuR and VEGF were elevated, as detected by western blotting, however, upon treatment with siRNA HuR their content was decreased. In particular, nanocarrier with a weak positive charge 4:1 N/P ratio (cationic lipid nitrogen to siRNA phosphate) showed better efficiency in transfection, remarkably decreasing the levels of HuR and VEGF. Thus, the results indicate that siRNA against HuR could be delivered with success by utilizing lipid-based nanocarriers and can be considered as potential candidates to control retinal diseases.

Effetto di nanocarriers a base di lipidi caricati con un siRNA silenziare l'espressione di HuR nella retina di ratti diabetici