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Defective negative regulation of Toll-like receptor signaling leads to excessive TNF-α in myeloproliferative neoplasm

Hew Yeng Lai, Stefan A. Brooks, Brianna M. Craver, Sarah J. Morse, Thanh Kim Nguyen, Nahideh Haghighi, Michael R. Garbati and Angela G. Fleischman

Data supplements

Article Figures & Data

Figures

  • Figure 1.

    Increased TNF-α production by MPN monocytes after stimulation with TLR agonists. (A) MPN (n = 2 PV, 2 ET, and 1 MF) and normal (n = 5) monocytes were stimulated with TLR agonists LPS or R848 at the concentrations shown. After 24 hours of culture, supernatant was harvested and TNF-α was measured by ELISA. (B) MPN (n = 8 PV, 3 ET, and 2MF) and normal (n = 8) monocytes were stimulated with 10 ng/mL LPS or 5 μM R848 and incubated with brefeldin A for 4 hours to prevent protein export. Intracellular staining for TNF-α was performed, and cells were analyzed by flow cytometry. (C) MPN (n = 2 PV and 5 ET) and normal (n = 5) monocytes were stimulated with 10 ng/mL LPS or 5 μM R848 for 15 minutes or 2 hours before fixation and permeabilization. Cells were stained for phospho-p38 and analyzed on a flow cytometer. *P < .05.

  • Figure 2.

    MPN monocytes persistently produce high levels of TNF-α. (A) MPN (n = 7 PV, 5 ET, and 4 MF) and normal (n = 13) monocytes were stimulated with 10 ng/mL LPS for 4, 9,18, and 24 hours before harvesting supernatant for ELISA. The amount of TNF-α produced at 4 hours was normalized to 1. (B) MPN (n = 5 PV, 4 ET, and 2 MF) and normal (n = 6) monocytes were stimulated with 10 ng/mL LPS for 4, 8, 13, and 22 hours before harvesting for flow cytometry analysis. All samples were treated with brefeldin A for 4 hours before harvesting. The percentage of monocytes expressing TNF-α at 4 hours was normalized to 1. *P < .05.

  • Figure 3.

    MPN monocytes produce adequate IL-10 but are less responsive to IL-10. (A) MPN (n = 4 PV, 4 ET, and 3 MF) and normal (n = 7) monocytes were stimulated with 10 ng/mL of LPS for 4, 9, 18, and 24 hours before harvesting supernatant for quantification of IL-10 via ELISA. (B) MPN (n = 2 PV and 3 ET) and normal (n = 6) monocytes were stimulated with 10 ng/mL LPS and various concentration of IL-10 simultaneously for 4 hours between harvesting of the supernatant for ELISA. The percentage change in TNF-α is measured by the difference in TNF-α production between adding IL-10 and without IL-10. (C) MPN (n = 2 PV and 3 ET) and normal (n = 5) monocytes were stimulated with 10 ng/mL LPS and various concentrations of IL-10 for 4 hours with brefeldin A before performing intracellular staining for TNF-α. The changes in TNF-α–positive monocytes are measured by the difference in monocytes expressing TNF-α between adding IL-10 and without IL-10. (D) The mean fluorescence intensity (MFI) of IL-10 receptor α is measured by gating on MPN (n = 4 PV, 3 ET, and 2 MF) and normal (n = 5) CD33high CD14+ monocytes from mononuclear cells, using flow cytometry analysis. *P < .05. ns, not significant.

  • Figure 4.

    MPN monocytes have defective IL-10 signaling. (A) MPN (n = 9 PV, 6 ET, and 4 MF) and normal (n = 18) peripheral blood was stimulated for 15 minutes with IL-10 at the concentrations shown before fixation and permeabilization. CD33 high Cd14+ monocytes were gated for pStat3 and analyzed via flow cytometry. (B) MPN (n = 2 PV and 1ET) and normal (n = 3) monocytes were stimulated with IL-10 for 15 minutes, 1 hour, or 2 hours at the concentrations shown. SOCS3 mRNA was quantified by quantitative PCR and normalized to β-actin. *P < .05.

  • Figure 5.

    IL-10R blocking is correlated to elevated TNF-α. (A) Normal monocytes (n = 2 PV, 2 ET, and 1 MF) were stimulated with 10 ng/mL LPS and with the addition of 1 μg/mL anti-IL-10R. Supernatants were collected for TNF-α quantification by ELISA at 4, 9, 18, and 24 hours after LPS stimulation. The amount of TNF-α produced at 4 hours was normalized to 1. (B) The correlation of TNF-α persistence score in MPN monocytes (n = 14) is defined as (TNF-α at 24 hours)/(TNF-α at 4 hours), and IL-10 resistance score is defined as (TNF-α of LPS + 1 ng/mL IL-10)/(TNF-α of LPS + 0 ng/mL IL-10). Pearson r = 0.7198, R2 = 0.5181. *P < .05.

  • Figure 6.

    Persistent TNF-α production and IL-10R signaling defects are found in an unaffected twin of a patient with MPN. (A) The monocytes of a patient with MPN, the unaffected twin of the patient, and normal donors (n = 2) were stimulated with 10 ng/mL LPS for 4, 9, 18, and 24 hours before supernatants were harvested for ELISA. The amount of TNF-α produced at 4 hours was normalized to 1. (B) The same supernatants harvested in A were taken for quantifying IL-10. (C) The monocytes of a patient with MPN, the unaffected twin of the patient, and normal donors (n = 2) were stimulated with 10 ng/mL LPS and various concentration of IL-10 simultaneously for 4 hours between harvesting of the supernatant for TNF-α ELISA. The percentage change in TNF-α is measured by the difference in TNF-α production between adding IL-10 and without IL-10.

  • Figure 7.

    Model of LPS-induced inflammation in normal and MPN monocytes. MPN and normal monocytes produce a similar level of TNF-α in early times on LPS stimulation. Normal monocytes respond to IL-10 inhibition to abolish TNF-α production in late times, whereas MPN monocytes have a blunted response to IL-10 inhibition resulting in an overproduction of TNF-α.

Tables

  • Table 1.

    JAK2V617F allele burden in TNF-α+ monocytes

    Patient4 h10 h
    TNF-αTNF-α+TNF-αTNF-α+
    19292.2157.5285.5882.65
    22863.6657.9290.0178.10
    23234.8842.6653.1351.90
    25294.8490.5066.2063.45
    25520.9576.8675.2480.23
    • MPN monocytes (n = 5) were stimulated with 10 ng/mL LPS for 4 or 10 hours in the presence of brefeldin A, and intracellularly stained for TNF-α. TNF-α+ cells were sorted and JAK2V617F allele burden was determined by quantitative PCR.