https://doi.org/10.1007/s00392-025-02625-4
1Universitätsklinikum Heidelberg Klinik für Innere Med. III, Kardiologie, Angiologie u. Pneumologie Heidelberg, Deutschland
The broad utilization of immune checkpoint inhibitors (ICIs) dramatically improved cancer prognosis but recently leads to an increase in the severe adverse events of ICI-associated myocarditis (ICIM). So far, the underlying pathway is not fully understood.
In order to investigate the patho mechanism further, we aimed to characterize transcriptional consequences in patients’ biopsies to explore ICIM-defining changes. We found 3784 unique upregulated genes in ICIM (FDR<0.05) compared to virus induced myocarditis or dilatative cardiomyopathy. Overlap to an in vitro co-culture model, using neonatal rat cardiomyocytes (NRVM) and human mononuclear cells (PBMC+ICI) identified GBP5 as the most upregulated cardiomyocyte-specific gene (fc NRVM+PBMC+PD1i/NRVM+PBMC=2.12, p=0.0289, Mann-Whitney Test).
To further investigate the biological relevance of GBP5 in the development of ICIM we used the CRISPR/Cas9 system to generate a cardiomyocyte-specific Lox/Cre-induced truncation of GBP5 in C57BL6 mice (GBP5-cKI). The inducible truncation results in a dysfunctional shorter protein (lacking the C-terminus of GBP5) which disrupts the inflammasome assembly in cardiomyocytes. Both tumor-bearing and non–tumor bearing mice (RET melanoma model) were subjected to combination of anti–PD-1 and anti–CTLA-4 antibody treatment. In total, 6 groups of mice were further investigated. 2 groups of mice (WT vs. GBP5-cKI) also received 40.000 IU IFNg in addition to ICI to further boost the immune reaction.
While ICI-treatment lead to significant increase in T-cell infiltration in wildtype (WT) animals, GBP5-cKI blunted this effect. Combination of ICI lead to a significant upregulation of inflammation-associated genes (e.g., IL1b, Caspase 1) in the heart of WT but not in GBP5-cKI. Expression of beta myosin heavy chain (mhy7) was significantly induced in WT animals but not in GBP5-cKI, suggesting a protective role for pathological cardiac remodeling.
GBP5-cKI showed a preserved left ventricular ejection fraction (LVEF) on ICI therapy compared to WT (LVEF mean ± SEM: GBP5-cKI+ICI (n=9) 50.2%±4.7%, GBP5-cKO+ICI+IFNg (n=10) 49.42%±3.4 % GBP5-KI (n=10) 49.51%±3.2%; p>0.99; Anova test with Bonferroni post test vs. WT untreated (n=10) 52.53% ± 3.9 vs. WT+ICI (n=6) 46.0%±5,5,% vs. WT+ICI+IFNg (n=7) 42.20%±5.6%; p<0.01, Anova test with Bonferroni post test).
In conclusion, our results highlights a previous unknown role of the inflammasome pathway in cardiomyocytes and identifies the C-terminal GBP5 in as a novel potential target to protect from ICIM.