Bhlhe40: Required For Tumor Microenvironment Remodeling and Immune Checkpoint Therapy Efficacy

<p>Advancements in immunotherapy treatments have become essential in the treatment of various cancers, such as those with high tumor burden like melanoma(Brahmer et al., 2012; Hodi et al., 2010). Immunotherapy, specifically immune checkpoint therapy (ICT) provides antagonist effect on specific immune checkpoints to control effector T cell functions(Pardoll, 2012). This therapy allows for the modulation of anti-tumor responses through the use of monoclonal antibodies, such as anti-CTLA-4 or anti-PD-1 that block the receptors from binding with their ligands, thus allowing for CD4⁺ and CD8⁺ T cell priming and activation(Wei et al., 2017). However, the required epigenetic and transcriptional features that T cells must possess to efficaciously respond to ICT remains unclear. We show the transcription factor BHLHE40 is required in T cells for effective ICT response in mice bearing immune-edited tumors. Furthermore, we show BHLHE40 is upregulated in tumor antigen-specific CD8⁺ and CD4⁺ T cells upon ICT treatment with anti-CTLA-4 or anti-PD-1. Using single-cell RNA sequencing (scRNAseq), we revealed ICT-induced immune compartment remodeling in intratumoral immune cells taken from BHLHE40-deficent mice.</p> <p>These BHLHE40-dependent gene expression changes indicated dysregulated metabolism, NF-kB signaling, and IFNg response within certain subpopulations of CD4⁺ and CD8⁺ T cells. Intratumoral CD4⁺ and CD8⁺ T cells from BHLHE40-deficient mice also exhibited higher expression of the inhibitory receptor gene <em>Tigit</em> and displayed alterations in chemokine/chemokine receptor gene expression with altered gene expression of granzyme family members. Mice lacking BHLHE40 had reduced ICT-driven IFNg production by CD4⁺ and CD8⁺ T cells and defects in ICT-induced remodeling of macrophages from a CX3CR1⁺CD206⁺ subpopulation to an iNOS⁺ subpopulation that is typically observed during effective ICT. Although both anti-PD-1 and anti-CTLA-4 ICT in BHLHE40-deficient mice lead to tumor outgrowth, several BHLHE40-dependent alterations were specific to the ICT that was used. Our results reveal a crucial role for BHLHE40 in effective ICT and suggest that BHLHE40 may be a predictive or prognostic biomarker for ICT efficacy and a potential therapeutic target.</p>

Name thesis:degree_name

Masters of Science (MS)

Level thesis:degree_level

Thesis (MS)

Year dc:date.available

2022

Authors dc:creator

• Salmon, Avery
• Salmon, Avery J
• <p>https://orcid.org/0000-0003-3470-0921</p>

Contributors dc:contributor

• Matthew Gubin
• Stephanie Watowich
• Michael Curran

• BHLHE40
• ICT
• anti-CTLA-4
• anti-PD-1
• scRNAseq
• biomarker
• Biological Phenomena, Cell Phenomena, and Immunity
• Translational Medical Research

Repository record dc:identifier

https://digitalcommons.library.tmc.edu/utgsbs_dissertations/1207

OAI identifier oai:identifier

oai:digitalcommons.library.tmc.edu:utgsbs_dissertations-2264