CX3CL1/Fractalkine and its Receptor CX3CR1 Are Involved in the Proliferation and Migration of Human Trabecular Cells

Abstract

Purpose: : to investigate in vitro whether the chemokine CX3CL1 could influence cell viability, proliferation and migration of glaucomatous trabecular cells (TC).

Methods: : human TCs (HTM3 cell line) obtained from a glaucomatous patient were assessed for basal and TGF-β2-induced expression of CX3CL1/CX3CR1 using RT-PCR and flow cytometry (FCM). CX3CL1 and TGF-β2 effects on cell proliferation and apoptosis were evaluated using BrDU staining in flow cytometry (FCM) and Hoechst33342/neutral red assays in microplate cytofluorometry. TC migration in response to CX3CL1 was assayed using 8-µm pore size transwells.

Results: : TCs expressed CX3CL1 at low level under basal conditions which slightly increased in TGF-β2-stimulated TCs as compared to unstimulated controls (P<0.05). Expression of CX3CR1 was high and strongly increased under TGF-β2 stimulation (P<0.01). Exogenous CX3CL1 increased TC proliferation (P<0.05). In contrast, TGF-β2 reduced cell proliferation (P<0.01) and induced apoptosis alone or in combination with CX3CL1. TCs were able to migrate in response to CX3CL1. Preincubation with TGF-β2 enhanced the chemotactic effect of CX3CL1 on TCs (P<0.05).

Conclusions: : CX3CL1/CX3CR1 are involved in glaucomatous TC survival and migration. TGF-β2, a key cytokine known to be overexpressed during glaucoma, could regulate the TM microenvironment by modulating TC response to CX3CL1.

Keywords: trabecular meshwork • inflammation • proliferation