JAK-STAT pathway activation in malignant and nonmalignant cells contributes to MPN pathogenesis and therapeutic...

Area of Science:

• Hematology
• Molecular Biology
• Immunology

Background:

• Myeloproliferative neoplasms (MPNs) are characterized by increased inflammatory cytokines.
• JAK kinase inhibitors, such as ruxolitinib, are used to treat MPNs, but their precise mechanism of action is not fully understood.
• Aberrant cytokine production by hematopoietic cells contributes to MPN pathophysiology.

Purpose of the Study:

• To elucidate the mechanisms by which JAK inhibitors attenuate cytokine-mediated pathophysiology in MPNs.
• To investigate the role of STAT3 signaling in MPN pathogenesis and response to JAK inhibition.

Main Methods:

• Single-cell profiling of hematopoietic cells from MPN models and patient samples.
• Genetic deletion of STAT3 in pan-hematopoietic and MPN-specific compartments.
• Assessment of disease severity and cytokine secretion levels.

Main Results:

• Hematopoietic cells in MPN models and patients aberrantly secrete inflammatory cytokines.
• Pan-hematopoietic STAT3 deletion reduced disease severity and cytokine secretion, similar to ruxolitinib therapy.
• STAT3 deletion restricted to MPN cells did not impact disease severity or cytokine production.
• Both malignant and nonmalignant cells secrete cytokines, and JAK inhibition reduces this production in both populations.

Conclusions:

• JAK-STAT3-mediated cytokine production by both malignant and nonmalignant cells is a key driver of MPN pathogenesis.
• Therapeutic efficacy of JAK inhibition in MPNs requires targeting both malignant and nonmalignant cell populations.
• These findings offer novel insights into the therapeutic mechanisms of JAK kinase inhibitors in MPNs.