IL-6 induces Treg dysfunction in desiccating stress-induced dry eye disease

Area of Science:

• Immunology
• Ophthalmology
• Autoimmune Diseases

Background:

• Regulatory T cells (Tregs) are crucial for immune homeostasis.
• Treg dysfunction contributes to autoimmune disorders like dry eye disease (DED).
• In DED, Treg dysfunction permits T-helper 17 (Th17) cell-mediated ocular surface inflammation.

Purpose of the Study:

• To investigate the factors causing Treg dysfunction in DED.
• To identify specific cytokines involved in Treg impairment.
• To explore therapeutic strategies targeting Treg restoration in DED.

Main Methods:

• Compared Treg functional markers (FoxP3, CD25, CTLA-4) in DED and normal mice.
• Assessed expression of pro-inflammatory cytokine receptors (IL-6R, IL-17RA, IL-23R) on Tregs.
• Exposed normal Tregs to IL-6, IL-17, or IL-23 in vitro; evaluated Treg function and Th17 suppression.
• Utilized in vitro and in vivo IL-6 blockade in DED models.

Main Results:

• DED Tregs exhibited reduced expression of FoxP3, CD25, and CTLA-4.
• DED Tregs showed increased expression of IL-6R, IL-17RA, and IL-23R.
• IL-6 and IL-17 exposure decreased Treg markers and suppressive function; IL-6 had the most significant impact.
• IL-6 blockade restored DED Treg function and ameliorated disease severity.

Conclusions:

• Treg dysfunction in DED is significantly driven by Th17-associated cytokines, particularly IL-6.
• IL-6 directly impairs Treg suppressive capacity and immune homeostasis.
• Targeting IL-6 offers a promising therapeutic avenue for restoring Treg function and treating DED.