IFN Inhibits Cell Proliferation and Migration in Human Fetal Retinal Pigment Epithelium (hfRPE)

Abstract

Purpose:: To compare the effects of a pro-inflammatory cytokine mixture (ICM) and its components on the modulation of human fetal retinal pigment epithelial (hfRPE) cell proliferation and migration.

Methods:: Primary hfRPE cell cultures were obtained as previously described. Bromodeoxyuridine (BrdU) incorporation was used to test hfRPE cell proliferation and a wound healing assay was used to test the effects of different inflammatory cytokines on cell migration. The apoptotic effect of inflammatory cytokines was detected using Annexin-V staining. Phalloidin staining was performed to check the distribution of actin cytoskeleton. The capacitance probe technique was used to measure transepithelial fluid transport (J_V) with concurrent transepithelial potential (TEP) and total tissue resistance (Rt) recordings.

Results:: A pro-inflammatory cytokine mixture (ICM) containing TNFα 10 ng/mL, IL-1ß 10 ng/mL and IFNγ 100 U/mL completely inhibited serum (5%) induced proliferation and migration, induced apoptosis and significant actin filament disruption in hfRPE monolayers. Further experiments showed that TNFα or IL-1ß per se had no significant effects on hfRPE cell proliferation and migration, but together they significantly inhibited cell proliferation (P<0.05; n=5). IFNγ inhibited proliferation and migration significantly more than ICM; IFNγ also inhibited proliferation and migration significantly more than either TNFα + IFNγ or IL-1ß + IFNγ (P<0.05; n=5,4 respectively). Previous localization experiments suggest that the receptors for TNFα and IFNγ are mainly localized on the basolateral membrane while the receptor for IL-1ß is mainly localized at the apical membrane. Preliminary experiments (n=4) showed that addition of IFNγ to the basal bath significantly increased J_Vacross hfRPE monolayers.

Conclusions:: A pro-inflammatory cytokine mixture significantly inhibits cell proliferation and migration, induces apoptosis and cytoskeleton disruption in hfRPE cells. The strong inhibitory effects of IFNγ on hfRPE cell proliferation and migration as well as the stimulatory effects on fluid transport suggest an important role of IFNγ in RPE physiology and pathophysiology. Present results suggest a potential clinical use of IFNγ in proliferative retinopathies.

Keywords: retinal pigment epithelium • cytokines/chemokines • proliferation