Constitutive Chemokine CCR2 and CXCR4 Receptor Expression in Rodens Neuroretina

Abstract

Abstract: : Purpose: Chemokines are small proteins initially described for their role in immunity and inflammation. Chemokines are involved in the physiopathology of a wide range of ophthalmologic diseases such as uveitis, ischemia, vitreoretinal disorders or macular senescent degeneration. Nevertheless, their expression in neuroretina has never been reported so far. The goal of this study was to investigate the constitutive expression of the chemokine MCP–1 (monocyte chemo attractant protein–1,CCL2) and SDF–1 (Stromal cell derived factor–1,CXCL12) and their cognate receptors (CCR2 and CXCR4) in rodent neuroretina. Methods:Firstly , we analyzed the localization of specific MCP–1 binding sites on neuroretina using autoradiography method. Then, we study CCR2 and CXCR4 mRNAs expression in neuroretina by molecular approach (RT–PCR). To further analyze, we precised the cellular distribution of CCR2 and CXCR4 in neuroretina and in neurotinal cells culture using immunolabelling method. Results:We demonstrated : (1) Specific MCP–1 binding sites are located in neuroretina. (2) CCR2 and CXCR4 mRNA were expressed in total RNA neuroretina extract ; (3) by immunohistochemistry, CCR2 constitutive expression is observed in ganglionnary cells, internal granulosa cells in particular horizontal cells, and only in mice, in external granulosa cells; CXCR4 constitutive expression is observed in Muller cells (4) MCP–1 and SDF–1 are not detectable in neuroretina slices but are expressed in neurons and glial cells in culture conditions. Conclusions: For the fist time, this study demonstrated a constitutive CCR2 and CXCR4 expression in neuroretina of rodents. Further studies will investigate the functional significance of these chemokine receptors expression in physiological and physiopathological conditions.

Keywords: retina