Graduate Research Assistant Augusta University Augusta, Georgia, United States
Disclosure(s):
Abdul Basit Musah: No financial relationships to disclose
Introduction/Rationale: T cells, particularly CD8⁺ T cells, play a central role in immune defense against intracellular pathogens and in tumor immunosurveillance. However, within tumors, these cells often become functionally exhausted, limiting the effectiveness of T cell–based immunotherapies. To maintain self-tolerance and immune homeostasis, T cell activity is tightly controlled by immunosuppressive mechanisms, including immune checkpoint molecules and anti-inflammatory cytokines. Among these, transforming growth factor-β (TGFβ) is a key pleiotropic cytokine known to suppress T cell responses.
Methods: To identify novel immunosuppressive genes downstream of TGFβ signaling, we performed mRNA sequencing of human CD8⁺ T cells activated with or without the addition of TGFβ. Differential gene expression analysis was conducted to identify TGFβ-regulated candidates. Functional validation was carried out using CRISPR-Cas9–mediated knockout in both Jurkat T cells and primary human CD8⁺ T cells to assess the role of identified genes in T cell function. In vivo studies involved adoptive transfer of gene-edited T cells into tumor-bearing mice to evaluate antitumor efficacy.
Results: Transcriptomic analysis revealed several genes upregulated by TGFβ, among which RGS16, a member of the regulator of G protein signaling (RGS) family, emerged as a strong candidate for a negative regulator of T cell function. Functional studies showed that RGS16 knockout markedly enhanced cytokine production, proliferation, and cytotoxic activity in both Jurkat cells and primary human CD8⁺ T cells. Moreover, adoptive transfer of RGS16-deficient T cells into tumor-bearing hosts led to improved tumor control and prolonged survival compared with controls.
Conclusion: Our findings identify RGS16 as a key downstream effector of TGFβ-mediated immunosuppression and a promising molecular target to potentiate T cell–based immunotherapies by restoring effector function under immunosuppressive conditions.
