Hematopoietic JAK2V617F mutation increases susceptibility to atrial fibrillation via NLRP3 inflammasome activation in macrophages Free

Clonal hematopoiesis of indeterminate potential (CHIP), an age-related phenomenon, elevates the risk of hematological malignancies and cardiovascular diseases. JAK2^V617F, a key driver mutation in CHIP and myeloproliferative neoplasms (MPNs), has emerged as a novel risk factor for cardiovascular diseases. Atrial fibrillation (AF), the most common arrhythmia, shares a similar onset age with MPNs and is linked to increased risks of thromboembolism and mortality. However, the direct causal relationship and underlying mechanisms between hematopoietic-specific JAK2^V617F mutation to AF remain unclear.A retrospective analysis of 1331 patients with myeloid malignancies was performed. Using Fine-Gray multivariable competing risk models adjusted for age, sex, and cardiovascular risk factors, the JAK2^V617F mutation was identified as an independent risk factor for new-onset AF (HR=2.20, 95%CI:1.45-3.35, P<0.001). Mediation analysis revealed that IL-1β played a significant mediating role in JAK2^V617F-promoted new-onset AF (HR=0.039, 95%CI:0.002-0.080, P=0.042). A hematopoietic-specific JAK2^V617F knock-in mouse model (JAK2VF) and littermate wild-type (WT) controls were used. In vivo invasive electrophysiology and ex vivo optical mapping showed that JAK2VF mice had significantly higher AF induction success rates and longer AF duration than WT mice (P<0.05). Regarding atrial structural remodeling: JAK2VF mice exhibited significant left atrial enlargement (P<0.05) and increased atrial fibrosis (P<0.05). Single-cell RNA sequencing of isolated left atrial tissues revealed a significantly activated phenotype of atrial fibroblasts in the JAK2VF group. CellChat analysis demonstrated enhanced macrophage-fibroblast interactions in the JAK2VF group. Further analysis showed that the proportion of CCR2⁺ macrophages in JAK2VFatrial tissues was significantly increased (P<0.05), along with upregulated expression of NLRP3 inflammasome-related genes Nlrp3 and Il1b (P<0.05). In the mouse model, the number of left atrial macrophages was significantly increased in the JAK2VFgroup, accompanied by NLRP3 inflammasome activation, with a significant co-localization of CD68 and NLRP3. Bone marrow-derived macrophages (BMDMs) from JAK2VFor WT mice were co-cultured with atrial fibroblasts from WT mice. JAK2VFBMDMs significantly promoted the expression of fibrosis-related proteins (collagen 1, α-SMA) in fibroblasts (P<0.05). Meanwhile, JAK2VFBMDMs showed significantly higher expression of key NLRP3 inflammasome components (NLRP3, ASC, Caspase-1) and elevated levels of IL-1β and IL-18 in the supernatant compared to WT BMDMs (all P<0.05). In addition, a retrospective analysis of the JAK2^V617F-mutant patient cohort showed that patients receiving the JAK1/2 inhibitor ruxolitinib had a significantly lower incidence of new-onset AF than those not receiving ruxolitinib.In conclusion, this study is the first to demonstrate that the hematopoietic JAK2^V617F mutation is an independent risk factor for new-onset AF in both human populations and animal models. Mechanistically, this effect is mediated primarily by JAK2^V617F-positive macrophages through activating the NLRP3 inflammasome and releasing cytokines such as IL-1β, thereby driving atrial fibroblast activation and atrial structural remodeling. Clinical data indicate that ruxolitinib may reduce AF risk in JAK2^V617F-mutant patients by inhibiting the JAK-STAT pathway and downstream inflammation. Our findings not only elucidate a novel mechanism by which CHIP, particularly JAK2^V617F, promotes AF but also provide strong experimental and clinical evidence for targeting inflammatory pathways by using JAK inhibitors in the prevention or treatment of CHIP/MPN-related AF, warranting prospective studies for validation.