Abnormal retinal vascular development in IL-18 knockout mice

Area of Science:

• Ophthalmology
• Developmental Biology
• Immunology

Background:

• The precise role of interleukin 18 (IL-18) in vascular development remains uncertain, with conflicting evidence suggesting it may promote or inhibit blood vessel formation.
• Understanding IL-18's function is critical for elucidating mechanisms underlying vascular development and related pathologies.

Purpose of the Study:

• To investigate the specific role of IL-18 in the development of retinal vasculature.
• To determine the impact of IL-18 deficiency on retinal angiogenesis and vascular integrity.

Main Methods:

• Comparison of retinal vascular development in IL-18 knockout (KO) and wild-type (WT) mice using angiography and histological examination.
• Analysis of angiogenic factor expression (VEGF, bFGF, PDGF, PEDF) via reverse-transcription-polymerase chain reaction.
• Assessment of vascular leakage and abnormalities at various postnatal time points.

Main Results:

• IL-18 KO mice exhibited transient angiectasis and vascular leakage in the mid-peripheral retina by postnatal day 7, unlike WT mice.
• Histopathological analysis revealed abnormal vascular formation in IL-18 KO mice at postnatal day 14.
• Overexpression of key angiogenic factors (VEGF, bFGF, PDGF, PEDF) was observed in IL-18 KO retinas, while interferon-gamma was present only in WT retinas.
• Retinal abnormalities in IL-18 KO mice showed spontaneous regression by postnatal day 84.

Conclusions:

• Interleukin 18 (IL-18) is essential for normal retinal vascular development, preventing transient abnormalities.
• IL-18 deficiency leads to temporary dysregulation of angiogenic factors and vascular integrity in the developing retina.
• The findings highlight a novel regulatory role for IL-18 in the intricate processes of retinal angiogenesis.