Background In both chronic virus infection and cancer settings, antigen-experienced CD8⁺ T cell can differentiate into either effector or exhausted branches. While transcriptional and epigenetic control of the development of exhausted CD8⁺ T cells are relatively well-described,^{1 2} little is known about how the generation and maintenance of the effector population is regulated.

Zinc-Finger Protein 148 (ZFP148) is one of the Kruppel family of zinc finger transcription factors and has been reported to regulate CD4⁺ T cell thymic development and differentiation.³ However, its role in regulating the differentiation of CD8⁺ T cells remains elusive. Here, we described the novel role of ZFP148 in inhibiting the generation of effector CD8⁺ T cells and its direct transcriptional repression of GZMB. Furthermore, genetic deletion of ZFP148 specifically in CD8⁺ T cells significantly enhance the responsiveness of mice to anti-PD1 immune checkpoint blockade (ICB) therapy.

Methods In the following study, we utilized both RNP-based CRISPR knockout (KO) of ZFP148 and a CD8⁺ T cells-specific ZFP148 deletion mouse model to study the role of ZFP148 in regulating CD8⁺ T cell differentiation. we applied both chronic lymphocytic choriomeningitis virus (LCMV) infection and multiple syngeneic mouse tumor models to both control and ZFP148 KO mice with or without ICB treatment, which were followed by assessment of disease progression, T cell functionality, T cell differentiation status, and further responsiveness to ICB therapy. Mechanistically, we also utilized matched single-cell RNA sequencing and single-cell assay for transposase-accessible chromatin with sequencing to investigate how ZFP148 transcriptionally and epigenetically fine tunes the effector differentiation of antigen-specific CD8⁺ T cells.

Results We observed that ZFP148 is highly expressed in progenitor-like CD8⁺ T cells compared to effector and exhausted subpopulations in both mouse chronic LCMV infection and human pan-cancer single-cell RNA-seq data analysis. Loss of ZFP148 in CD8⁺ T cells drives their differentiation into a highly cytotoxic effector-like population in both chronic LCMV and syngeneic tumor model settings. Furthermore, CD8⁺ T cell-specific ZFP148 KO mice exhibit superior responsiveness to anti-PD1 ICB therapy compared with control mice, along with increased number of tumor-infiltrating CD8⁺ T cells and improved functionality.

Conclusions We identified ZFP148 as a novel transcription factor that can regulate CD8⁺ T cell effector differentiation and responsiveness to anti-PD1 ICB therapy. ZFP148 can also serve as a promising biomarker for predicting responsiveness to ICB therapy in cancer patients.

References

1. Chen Z, et al. TCF-1-Centered transcriptional network drives an effector versus exhausted CD8 T cell-fate decision. Immunity 2019;51(5):840–855 e5.

2. Khan O, et al. TOX transcriptionally and epigenetically programs CD8(+) T cell exhaustion. Nature 2019;571(7764):211–218.

3. Chopp LB, et al. Zfp281 and Zfp148 control CD4(+) T cell thymic development and T(H)2 functions. Sci Immunol 2023;8(89):eadi9066.