The CXCL10/CXCR3 axis is critically involved in retinal inflammation and ganglion cell injury.

Abstract

Purpose : Loss of retinal ganglion cells (RGCs) is an essential pathological process in glaucoma, yet mechanisms responsible for RGC death remain unclear. CXCL10 is a chemokine that induces the recruitment and activation of inflammatory cells after binding to its receptor CXCR3. This study is to determine whether the CXCL10/CXCR3 axis-mediated inflammation plays an important role in RGC dysfunction and death in glaucoma.

Methods : Studies were performed in two mouse models related with glaucoma. The optic nerve crush (ONC) model was used to study RGC death after axonal injury, which was induced by a transient crush of optic nerve (ON) behind the eye globe. The microbeads-induced glaucoma (MIG) was used to study RGC injury by increasing intraocular pressure (IOP), which was induced by injecting a mixture of 10 μm and 1 μm polystyrene microbeads into anterior chamber to partially block aqueous humor drainage through trabecular meshwork. Retinas were collected from 1 hour to 7 days after ONC or 5-42 days after microbeads injection for quantitative PCR and histological studies. In vitro studies were performed using primary RGCs and leukocytes isolated from mice.

Results : In ONC model, we found levels of CXCL10 and CXCR3 mRNA and protein were markedly elevated after axonal injury. CXCL10 mRNA positive cells were distributed in cells including RGCs near the ON head, and the immunoreactivity for CXCR3 was increased in cells in the ganglion cell layer. Upregulation of CXCL10/CXCR3 was associated with recruitment of leukocytes into the retina. In vitro co-culture of RGCs with leukocytes resulted in a 3.2-fold increase in RGC apoptosis. Deleting CXCR3 in bone marrow cells significantly reduced leukocyte recruitment and prevented RGC death after ON injury. Pharmacological blockade of CXCR3 with AMG487 (20 mg/kg) partially prevents RGC dysfunction and cell loss after axonal injury. In MIG model, IOP was chronically elevated with higher than 21 mm Hg in the microbead-injected eye, which was associated with significant increases in CXCL10 expression, monocyte/microglia recruitment and RGC loss.

Conclusions : These data suggest that CXCL10/CXCR3 signaling plays an important role in the development and progression of glaucomatous neuropathy.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.