The role of circulating monocytes and JAK inhibition in the infectious-driven inflammatory response of myelofibrosis

ABSTRACT

Myelofibrosis (MF) is characterized by chronic inflammation and hyper-activation of the JAK-STAT pathway. Infections are one of the main causes of morbidity/mortality. Therapy with Ruxolitinib (RUX), a JAK1/2 inhibitor, may further increase the infectious risk. Monocytes are critical players in inflammation/immunity through cytokine production and release of bioactive extracellular vesicles. However, the functional behavior of MF monocytes, particularly during RUX therapy, is still unclear. In this study, we found that monocytes from JAK2V617F-mutated MF patients show an altered expression of chemokine (CCR2, CXCR3, CCR5) and cytokine (TNF-α-R, IL10-R, IL1β-R, IL6-R) receptors. Furthermore, their ability to produce and secrete free and extracellular vesicles-linked cytokines (IL1β, TNF-α, IL6, IL10) under lipopolysaccharides (LPS) stimulation is severely impaired. Interestingly, monocytes from RUX-treated patients show normal level of chemokine, IL10, IL1β, and IL6 receptors together with a restored ability to produce intracellular and to secrete extracellular vesicles-linked cytokines after LPS stimulation. Conversely, RUX therapy does not normalize TNF-R1/2 receptors expression and the LPS-driven secretion of free pro/anti-inflammatory cytokines. Accordingly, upon LPS stimulation, in vitro RUX treatment of monocytes from MF patients increases their secretion of extracellular vesicles-linked cytokines but inhibits the secretion of free pro/anti-inflammatory cytokines. In conclusion, we demonstrated that in MF the infection-driven response of circulating monocytes is defective. Importantly, RUX promotes their infection-driven cytokine production suggesting that infections following RUX therapy may not be due to monocyte failure. These findings contribute to better interpreting the immune vulnerability of MF and to envisaging strategies to improve the infection-driven immune response.

KEYWORDS:

• Myelofibrosis
• monocyte
• ruxolitinib
• extracellular vesicles

Acknowledgments

We greatly thank Novartis Pharma AG for providing the active drug substance for the in vitro experiments. This work was funded by AIL Bologna and RFO 2017/2018 (L.C.). D.F. was supported by AIRC (fellowship 20930-2018) and by SIE-Società Italiana di Ematologia- e Associazione “Amici di Beat Leukemia Dr. Alessandro Cevenini ONLUS”.

Author contributions

M.B., F.R., M.R., D.F., and L.C. contributed to study design, statistical analysis, and data interpretation. F.P., G.A., and N.V. managed patients and collected blood samples. M.B. and F.R. performed monocytes, extracellular vesicles, cytokine analysis, and data interpretation. E.O. performed molecular analysis. M.B. and D.B. were involved in statistical analysis. M.B., M.R., D.F., F.P. and L.C. wrote or contributed to the writing of the manuscript. P.L.T. and M.C. reviewed and corrected the manuscripts. All Authors read and contributed to the final version of the manuscript.

Disclosure of potential conflicts of interest

The authors declare that they have no competing interests.

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website.

Additional information

Funding

This work was supported by AIL Bologna; SIE-Società Italiana di Ematologia e Associazione “Amici di Beat Leukemia Dr. Alessandro Cevenini ONLUS”; AIRC [fellowship 20930-2018]; University of Bologna [RFO 2017/2018].