Abstract
Inflammatory signaling contributes to the progression of acute myeloid leukemia (AML) and impaired hematopoiesis, partly through NF-kB–driven transcription of cytokines, such as IL-6, IL-8, and IL-1β. These factors disrupt the bone marrow niche and support leukemic cell survival. In concordance, low expression of the interleukin-1 receptor (IL1R1), the receptor for IL-1β, has been linked to a more favorable outcome in AML. However, its role in genetically defined subgroups remains unclear. Here, we report that low IL1R1 expression was particularly associated with IDH1-mutated (mut) AML. To characterize IL1R1 in IDH1-mut AML, we combined clinical data with transcriptomic, epigenetic, and cellular analyses using primary AML blasts as well as CRISPR-modified IDH1 p.R132H mutant KG1-a AML cells.
Using transcriptome data from the BeatAML2.0 study, we identified significant downregulation of IL1R1 mRNA expression in IDH1-mut compared to IDH1-wild-type (wt) AML cases (log₂ fold change = -1.23; adjusted p-value = 0.017). Given the known epigenetic alterations associated with IDH1 mutations, DNA methylation was examined and revealed significant hypermethylation at 6 out of 18 CpG sites (33%) across the IL1R1 locus in IDH1-mut compared to IDH1-wt AML cases. To analyze the clinical impact of reduced IL1R1 levels, all AML patients from the BeatAML2.0 study were stratified into three IL1R1 expression groups: high (n = 205), medium (n = 205) and low (n = 205). Overall, AML patients with low IL1R1 expression showed significantly higher complete remission (CR) rates (56.2%) compared to those with medium (44.1%) or high expression (38.1%; p = 0.0014). Stratified analyses by IDH1 mutation status confirmed higher CR rates in IL1R1-low cases in IDH1-wt (low 54.2% vs. medium 43.9% vs. high 38.5%, p = 0.003) as well as IDH1-mut subgroups (low 69.2% vs. medium 46.7% vs. high 28.6%, p = 0.046). Independent of the IDH1 genotype, Kaplan-Meier survival analysis demonstrated that low IL1R1 expression was associated with significantly improved overall survival compared to medium and high expression (median 680 vs. 320 vs. 434 days; p = 0.0001). Notably, IDH1-mut cases were significantly enriched in the IL1R1 low expression group (13.4%) compared to medium (7.7%) and high (3.6%) expression groups (p = 0.002), suggesting IL1R1 expression as clinical discriminator with particular relevance in IDH1-mut AML. For functional validation primary AML blasts were treated with IL-1β, the canonical IL1R1 agonist. In IDH1-mut AML blasts, IL-1β exposure led to lower mRNA expression of TNF, IL6, and CCL20 compared to IDH1-wt primary AML blasts. On the protein level, IL-1β stimulation of IDH1-mut KG1-a cells led to significantly lower IL-8 secretion compared to IDH1-wt cells at 6 h and 18 h. Proteomic profiling confirmed reduced secretion of NF-kB–dependent cytokines such as IL-8, CXCL1, and CCL20 in IDH1-mut KG1-a cells. In contrast, IL-1β induced higher secretion of tissue remodeling and immune modulatory proteins such as MMP-1, MMP-10, PLAU and TNFSF10 in IDH1-mut KG1-a cells. To mimic the inflammatory bone marrow microenvironment containing high levels of several pro-inflammatory cytokines, stimulation with conditioned medium (CM) of HS-5 stromal cells was performed. Exposure to HS-5 CM led to a time-dependent increase in caspase-3/7 activation, which was significantly more pronounced in IDH1-mut cells compared to IDH1-wt cells (p = 0.02). The enhanced apoptotic response of IDH1-mut cells to both recombinant IL-1β and HS-5 CM was abrogated by the IL-1 receptor antagonist Anakinra, indicating a selective IL1R1-dependent apoptosis induction in IDH1-mut AML cells.These results suggest that IDH1 mutations in AML remodel IL1R-mediated signaling towards an inflammatory anergy but pro-apoptotic state, revealing a previously unrecognized inflammatory vulnerability in this genetic subtype involving the leukemic microenvironment. This work provides a rationale for further investigation of targeted pro-inflammatory modulation or combination regimens to amplify apoptosis in IDH1-mut AML selectively.
