STAT6 inhibition stabilizes induced regulatory T cells and enhances their therapeutic potential in inflammatory bowel disease

TL;DR

Blocking STAT6 signaling improves the stability and effectiveness of regulatory T cells, making them better at treating inflammatory bowel disease.

Contribution

STAT6 inhibition is shown to enhance iTreg stability and therapeutic efficacy in inflammatory bowel disease models.

Findings

STAT6 inhibition maintains high Foxp3 and suppressor molecule expression in iTregs under inflammatory conditions.

AS-iTregs reduce disease severity and epithelial damage in a DSS colitis model without promoting tumor growth.

In vivo STAT6 inhibition boosts Treg expansion and suppressive function during acute colitis.

Abstract

The development and stability of induced regulatory T cells (iTregs) are essential for their immunosuppressive function and therapeutic potential in inflammatory diseases. Although Treg-based immunotherapy offers promise for restoring immune tolerance, clinical application is limited by the instability and reduced potency of iTregs. STAT6 signaling has been implicated in destabilizing Foxp3 expression, a key marker of Treg identity. Here, we investigated the impact of pharmacological STAT6 inhibition on iTreg differentiation, stability, and function both in vitro and in vivo. Naïve CD4⁺ T cells were differentiated into iTregs under standard conditions or expanded with IL-2 in the presence of the STAT6 inhibitor AS1517499 (AS-iTregs). STAT6 inhibition enhanced iTreg stability, maintaining high expression of Foxp3, CD25, PD-1, and CTLA-4 for up to 10 days, even in inflammatory conditions. AS-iTregs also showed increased mRNA levels of Foxp3, IL-10, TGF-β, and PD-1, and reduced IL-6, IL-1β, and DNMT1 expression—suggesting improved functional and epigenetic stability. In the DSS colitis model, adoptive transfer of AS-iTregs alleviated disease severity, preserved mucosal architecture, and increased goblet cell numbers. Histopathological analysis showed reduced epithelial damage and inflammation compared to controls. Importantly, AS-iTregs did not promote tumor growth in a colitis-associated cancer model. Furthermore, in vivo administration of AS1517499 during acute colitis enhanced Treg expansion, activation, and suppressive function. These findings establish STAT6 inhibition as a promising approach to boost iTreg stability and efficacy, advancing the potential of Treg-based therapies for inflammatory disorders.

The online version contains supplementary material available at 10.1007/s12026-025-09686-7.

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