Philadelphia-negative myeloproliferative neoplasms (Ph-MPNs) are clonal hematologic malignancies characterized not only by driver mutations such as JAK2V617F, CALR, and MPL but also by a profoundly dysregulated immune microenvironment. Chronic inflammation and immune remodeling sustain malignant hematopoiesis and contribute to disease progression from essential thrombocythemia (ET) and polycythemia vera (PV) to overt myelofibrosis (MF). Pro-inflammatory cytokines and chemokines—including IL-2, IFN-α, IL-23, and TNF-α—drive abnormal T cell polarization, favoring a pathogenic Th17 phenotype. Lymphocyte subset analysis reveals a predominance of exhausted PD-1+ T cells, reflecting impaired immune surveillance. Concurrently, alterations in neutrophil apoptosis lead to persistent inflammation and stromal activation. GRO-α (CXCL1) is elevated in ET but reduced in MF, suggesting a subtype-specific role in disease biology. Fibrosis-promoting factors such as TGF-β and IL-13 mediate bone marrow remodeling and megakaryocyte expansion, while VEGF and other angiogenic factors enhance vascular niche alterations, particularly in PV. These immunopathologic features underscore novel therapeutic vulnerabilities. In addition to JAK inhibition, targeted strategies such as CXCR1/2 antagonists, anti-TGF-β agents, and immune checkpoint inhibitors (PD-1/PD-L1 blockade) may offer disease-modifying potential. Understanding the interplay between cytokine signaling and immune cell dysfunction is crucial for developing precision immunotherapies in MPNs.
Todor et al. (Mon,) studied this question.