Multifunctional Interleukin-24 Resolves Neuroretina Autoimmunity via Diverse Mechanisms

Area of Science:

• Immunology
• Ophthalmology
• Cytokine Biology

Background:

• Interleukin-24 (IL-24) is a cytokine with known roles in immune and epithelial cell regulation.
• Elevated IL-24 levels are linked to autoimmune diseases, but its tolerogenic effects on autoreactive T cells are a recent discovery.
• IL-24 has shown potential in inhibiting pathogenic Th17 responses in central nervous system (CNS) autoimmunity models.

Purpose of the Study:

• To investigate the therapeutic potential of IL-24 in experimental autoimmune uveitis (EAU), a model of ocular autoimmunity.
• To determine if IL-24 can inhibit the progression of ocular inflammation and suppress pathogenic immune responses in EAU.

Main Methods:

• Experimental autoimmune uveitis (EAU) was induced in wildtype mice.
• IL-24 was administered via intravitreal injection into inflamed eyes after disease onset.
• In vitro studies assessed IL-24's effect on Th1 and Th17 differentiation and cytokine production from retinal cells.

Main Results:

• Intravitreal IL-24 significantly inhibited the progression of ocular inflammation in EAU mice.
• IL-24 treatment suppressed cytokine production from infiltrating pathogenic Th1 and Th17 cells.
• IL-24 inhibited Th1 and Th17 differentiation in vitro by regulating T-bet and RORγt, and reduced pro-inflammatory mediators in EAU retinas.

Conclusions:

• IL-24 demonstrates significant efficacy in resolving ocular inflammation in a mouse model of autoimmune uveitis.
• The cytokine targets both uveitogenic T cells and retinal pigment epithelium (RPE) cells, suggesting a dual mechanism of action.
• IL-24 represents a promising therapeutic candidate for autoimmune uveitis and potentially other autoimmune eye conditions.