Investigation of mechanisms and predictive markers of immune checkpoint inhibitor-induced immune-related adverse events.

Abstract

bstract: Introduction: Immune-related adverse events (irAEs) are significant limitations to the use of immune checkpoint inhibitors (ICIs). Over half of the patients on these medications experience irAEs, which vary in severity and affected organ. The identification of susceptible patients through biological biomarkers and genetic variations, along with an understanding of the immune mechanisms underlying these reactions, is a crucial goal in this field. Method: Our study utilized various methods to detect serum biomarkers, including ELISA, immunohistochemistry, and transcriptomic RNA analyses. We employed in vitro assays to elucidate the modulating effects of HMGB1 on T-cell and Treg suppression functions that affect the immune response. Additionally, TaqMan assays and genome-wide association studies (GWAS) were used to identify single nucleotide polymorphisms (SNPs) of interest. Results: HMGB1 was significantly elevated in the serum of patients with ICI-induced irAEs, particularly in those with gastrointestinal (GI) irAEs. Colon biopsies from these patients showed marked decreases in nuclear staining, indicating cellular death and HMGB1 translocation. Different HMGB1 isoforms varied in their effects on CTLA4 expression on CD3+ T cells, with dsHMGB1 notably reducing it. The effect of dsHMGB1 on CTLA4 expression in Treg populations showed intra-variability between donors and influenced the suppression function of Tregs on CD8+ and CD4+ T cells, which relates back to CTLA4 expression on these cells. Unfortunately, SNPs in the main receptor of dsHMGB1 (TLR4/MD2) were not significantly associated with the phenotype. However, female patients and those with a history of allergic reactions were significantly more likely to develop irAEs. ARG1 – a marker for MDSC and M2, was found to be significantly expresses in patients experiencing irAE. In our GWAS 14 snps exceeded our suggestive threshol d, these SNPs were mapped to regions of genes related to autoimmune disease and cancer. Discussion: Our findings highlight HMGB1's significant role in mediating immune-related adverse events (irAEs) in patients treated with immune checkpoint inhibitors. Elevated HMGB1 levels, particularly noted in gastrointestinal irAEs, suggest its potential as a biomarker for irAE risk. Additionally, the influence of HMGB1 on CTLA4 expression in T cells and Tregs underscores 6 its impact on immune modulation. Despite the lack of significant associations with TLR4/MD2 SNPs, the identification of other genetic variants related to autoimmune conditions hints at a complex genetic underpinning that warrants further investigation to enhance irAE management strategies.