High cell-free (cf)DNA in patients with myelofibrosis (MF) is associated with adverse clinical outcomes, activation of the AIM2 inflammasome and elevated levels of inflammasome-related cytokine IL-18.

DE LUCA G; GOETTE NP; LEV PR; CAMACHO MF; CASTRO RÍOS MA; SACKMANN F; MOIRAGHI B; CORTES V; CAULA V; VERRI V; BENDEK G; CARRICONDO E; VICENTE A; VARELA A ; VALLEJOS V; GUTIERREZ M; LARRIPA IB; MARTA RF; GLEMBOTSKY AC; HELLER PG

Congreso; Congress of the International Society on Thrombosis and Haemostasis (ISTH); 2023

Background Myelofibrosis is a myeloproliferative neoplasm associated with poor outcome, caused by driver (JAK2/CALR/MPL) and high-risk mutations coupled to a chronic inflammatory process. cfDNA consists of short DNA fragments present in the non-cellular blood fraction. It has pro-inflammatory effects being one of its targets the AIM2 inflammasome, responsible for maturation and release of IL-1β and IL-18. Aims To assess whether cfDNA is useful as a biomarker for clinical outcome in MF and its contribution to the inflammatory state. Methods cfDNA was measured by fluorometry, IL-18 and C-reactive protein (CRP) by ELISA and AIM2 by qPCR. Results cfDNA was elevated in MF patients (n=72) vs. controls (P< 0.0001). We also found high levels of IL-18, an inflammasome product, in MF plasma (P< 0.0001), reflecting in vivo inflammasome activation. Close association was found between higher values of cfDNA and IL-18 and clinical complications, including cytopenias, constitutional symptoms, circulating blasts and shortened survival. High levels of both inflammatory mediators were also associated with adverse mutational profile and higher-risk categories (DIPSS/MIPSS70 scores) (P< 0.0001). Correlation was found between cfDNA, IL-18, LDH, and inflammatory marker CRP (P< 0.0001). Considering that monocytes are effectors of MF inflammation and that IL-18 correlated with monocyte counts, we assessed their contribution to systemic IL-18. Patient monocytes had increased AIM2 expression (P< 0.0001) and released higher IL-18 upon AIM2 stimulation with a synthetic DNA, (P< 0.01), indicating monocytes are a relevant source of IL-18 in MF. Both IL-18 and AIM2 were higher in JAK2V617F-positive patients. . Conclusion(s) Association between cfDNA and advanced disease suggests its potential role as prognostic factor in MF. The novel finding of elevated IL-18 reveals its involvement in MF cytokine network. Close correlation between cfDNA and systemic IL-18, together with enhanced monocyte AIM2 expression and function suggests cfDNA triggers inflammation through AIM2 inflammasome activation, revealing new players in MF inflammatory circuit.