Expression of Toll-Like Receptors in the Early Prenatal Development of the Human Retina

Abstract

The expression of Toll-like receptors TLR2 and TLR4 in the human retina during early prenatal development is shown for the first time. It was found that the development and differentiation of the retina is accompanied by specific spatial changes in the location of these receptors. TLR2 and TLR4 expression was detected in both neuroblastic retinal layers in gestation week 9. At subsequent developmental stages, the immunohistochemical staining for TLR2 and TLR4 gradually shifted towards the inner and outer plexiform layers of the retina and the nerve fiber layer. Our results suggest a possible involvement of these receptors in the regulation of neurogenesis and axonogenesis and the formation of synaptic connections between neurons and axons. The presence of TLR receptors in the endothelial cells forming retinal vessel walls does not exclude their role in the blood–retina barrier in pathogen infection.