204P - Effect of STAT6 Inhibition as a Novel Strategy for Promoting the Induction of Potent and Stable Regulatory T Cells for Use in Colitis Therapy

Background

Colorectal cancer (CRC) ranks among the leading global malignancies, characterized by high mortality and incidence rates. Furthermore, inflammatory bowel disease has been implicated in the development of CRC associated with colitis (CAC). STAT6 is notably hyperactivated in various tumors, including CRC. In experimental CAC models, STAT6 KO mice have demonstrated decreased tumor development, reduced disease aggressiveness, and a reduced local and systemic inflammatory response compared to WT mice. This phenomenon has been attributed to an increased presence of Tregs during the early stages of CAC development. As such, we seek to investigate the differentiation and functional characteristics of induced Tregs (iTregs) generated in the presence of the specific STAT6 inhibitor, AS1517499, and evaluate its therapeutic potential in an in vivo CAC model.

Methods

Naive CD4 T cells were isolated from Foxp3eGFP mice and cultured under Treg-polarizing conditions with or without AS1517499 for five days. Subsequently, cells were expanded with IL-2 supplementation over a total of 15 days, followed by staining with anti-CD4 and anti-CD25 antibodies and analysis via FACS. Foxp3+ cells were isolated and the extent of differentiation and suppressive capability of these cells were assessed. Next, 2.0 × 105 cells were injected into WT mice using an AOM/DSS regimen. Over ten weeks, we monitored changes in body weight, disease activity index, colon length, and tumor burden. Additionally, we evaluated the severity of colon inflammation and markers of carcinogenesis.

Results

iTregs induced under STAT6 inhibition exhibited prolonged expression of Foxp3 and CD25, even during inflammatory conditions. The transfer of Tregs/AS1517499 into WT mice in the AOM/DSS model resulted in a remarkable reduction in inflammation, decreased expression of inflammatory cytokines, and a reduction in epithelial cell proliferation.

Conclusions

iTregs developed under STAT6 inhibition demonstrate enhanced stability when compared to their littermate counterparts. The transfer of Tregs/AS1517499 during inflammatory states leads to an improvement in the disease status of CAC in the in vivo model.

Legal entity responsible for the study

The authors.

Funding

Consejo Nacional De Humanidades Ciencia Y Tecnologia De Mexico.

Disclosure

All authors have declared no conflicts of interest.