Neuropeptide Y regulates a vascular gateway for hematopoietic stem and progenitor cells
Pratibha Singh, … , Theresa A. Guise, Louis M. Pelus
Pratibha Singh, … , Theresa A. Guise, Louis M. Pelus
Published November 13, 2017
Citation Information: J Clin Invest. 2017;127(12):4527-4540. https://doi.org/10.1172/JCI94687.
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Research Article

Neuropeptide Y regulates a vascular gateway for hematopoietic stem and progenitor cells

Abstract

Endothelial cells (ECs) are components of the hematopoietic microenvironment and regulate hematopoietic stem and progenitor cell (HSPC) homeostasis. Cytokine treatments that cause HSPC trafficking to peripheral blood are associated with an increase in dipeptidylpeptidase 4/CD26 (DPP4/CD26), an enzyme that truncates the neurotransmitter neuropeptide Y (NPY). Here, we show that enzymatically altered NPY signaling in ECs caused reduced VE-cadherin and CD31 expression along EC junctions, resulting in increased vascular permeability and HSPC egress. Moreover, selective NPY2 and NPY5 receptor antagonists restored vascular integrity and limited HSPC mobilization, demonstrating that the enzymatically controlled vascular gateway specifically opens by cleavage of NPY by CD26 signaling via NPY2 and NPY5 receptors. Mice lacking CD26 or NPY exhibited impaired HSPC trafficking that was restored by treatment with truncated NPY. Thus, our results point to ECs as gatekeepers of HSPC trafficking and identify a CD26-mediated NPY axis that has potential as a pharmacologic target to regulate hematopoietic trafficking in homeostatic and stress conditions.

Authors

Pratibha Singh, Jonathan Hoggatt, Malgorzata M. Kamocka, Khalid S. Mohammad, Mary R. Saunders, Hongge Li, Jennifer Speth, Nadia Carlesso, Theresa A. Guise, Louis M. Pelus

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Figure 5

NPY3-36 reverses the CD26 activity inhibition- and gene deletion-mediated defect in HSPC mobilization and transendothelial migration.

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NPY3-36 reverses the CD26 activity inhibition- and gene deletion-mediate...
(A) Mass spectroscopic validation of DPP4-dependent proteolysis of NPY to NPY3-36. Purified NPY (1 μg) was treated with DPP4 (0.1 μg) overnight. (B) NPY levels in BM SECs and in BMEF from G-CSF–treated WT mice (mean ± SEM; n = 5 mice/group). Positive gates for NPY expression were based on FMO (green). (C) Transendothelial migration of LSK cells across BMECs treated with G-CSF, G-CSF plus diprotin A, or G-CSF plus diprotin A with NPY3-36 (mean ± SEM; n = 2 experiments; 3 mice/experiment). (D) Transendothelial migration of CD34+ cells across HUVECs treated with G-CSF, G-CSF plus diprotin A, or G-CSF plus diprotin A with NPY3-36 (mean ± SEM; n = 3 experiment; using 3 individual CB samples). (E and F) Blood CFU-Cell (CFU-C) and SLAM LSK cell counts in WT mice treated with G-CSF and in CD26–/– mice treated G-CSF, G-CSF plus NPY, or G-CSF plus NPY3-36 (mean ± SEM; n = 5 mice/group). (G) Donor chimerism in PB at 6 months in BoyJ mice competitively transplanted using equal volumes of PB from mice (C57BL/6) treated with G-CSF, G-CSF plus diprotin A, G-CSF plus diprotin A with NPY, or G-CSF plus NPY3-36 in combination with 200,000 BM cells from BoyJ mice (left) and tri-lineage reconstitution of donor cells (right) (mean ± SEM; n = 5 mice/group). (H) CFU-C mobilization in WT and NPY–/– mice treated with G-CSF, G-CSF plus diprotin A, or G-CSF plus diprotin A with NPY3-36 (mean ± SEM; n = 5 mice/group). (I) CFU-C mobilization in WT mice treated with G-CSF alone or with selective NPYR2 (BIIE 0246) or NPYR5 (CGP 71683 hydrochloride) inhibitors (mean ± SEM; n = 4 mice/group). *P < 0.05 compared with vehicle and †P ≤ 0.05 compared with G-CSF–treated WT mice, by Student’s t test (B) or 1-way ANOVA with Sidak’s multiple comparisons test (C–I).