Interleukin-18 induces retinal pigment epithelium degeneration in mice.

Investigative ophthalmology & visual science (2014-09-23)
Ryo Ijima, Hiroki Kaneko, Fuxiang Ye, Yosuke Nagasaka, Kei Takayama, Keiko Kataoka, Shu Kachi, Takeshi Iwase, Hiroko Terasaki
ABSTRACT

To examine the effectiveness of interleukin-18 (IL-18) on choroidal neovascularization (CNV) and retinal pigment epithelium (RPE) in humans and mice. Serum IL-18 levels in patients with wet and dry AMD who were older than 50 years were measured and compared with those of age-matched controls. In mice, laser photocoagulation was performed in the retina to induce experimental CNV, and CNV volume was measured in eyes injected with recombinant IL-18 (rIL-18) and IL-18 neutralizing antibody (nIL-18Ab) compared with those injected with control. Tube formation assay was performed on human retinal endothelial cells (HREC) with rIL-18 administration in vitro. After subretinal injection of rIL-18, fundus change in the injected eyes was evaluated; active caspase-3 level was measured in the RPE/choroid complex, and tight junction integrity in RPE was visualized by zonula occludens-1 (ZO-1) staining. Serum IL-18 levels in dry AMD patients were higher than those in control. Mouse rIL-18 or nIL-18Ab did not induce significant change in CNV volume compared with controls or change tube formation in HREC. Subretinal injection of rIL-18 induced retinal degeneration in the mice fundus; ZO-1 staining showed considerably disturbed RPE structure, and active caspase-3 expression was significantly higher after rIL-18 induction. Interleukin-18 did not show a pro- or antiangiogenic effect on mouse laser-induced CNVs (laser-CNVs), whereas it directly induced RPE cell apoptosis in the mouse eye. Our results suggested that IL-18 is associated with dry AMD, but not with wet AMD.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
RIPA Buffer
Sigma-Aldrich
1-Pentanol, ACS reagent, ≥99%
Sigma-Aldrich
1-Pentanol, ReagentPlus®, ≥99%
Sigma-Aldrich
1-Pentanol, puriss. p.a., ACS reagent, ≥99.0% (GC)
Supelco
1-Pentanol, analytical standard
Sigma-Aldrich
Amyl alcohol, ≥99%, FG
Phenylephrine, European Pharmacopoeia (EP) Reference Standard
Supelco
1-Pentanol, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
3-[(1R)-1-Hydroxy-2-(methylamino)ethyl]phenol, AldrichCPR