P2X4 receptor in human macrophages: role in ATP-evoked calcium responses and cytokine production

Layhadi, Janice (2017) P2X4 receptor in human macrophages: role in ATP-evoked calcium responses and cytokine production. Doctoral thesis, University of East Anglia.

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    P2X4 is a ligand-gated cation channel that is widely expressed amongst immune
    cells, especially in monocytes and macrophages. Despite its expression profile, the
    functional role of P2X4 in human macrophages has not been elucidated. This study
    aimed to (i) investigate the contribution of P2X4 towards ATP-evoked Ca2+
    responses and (ii) determine the role of P2X4 towards cytokine production in human
    macrophages. Here, human THP-1-differentiated macrophages (TDM) and primary
    monocyte-derived macrophages (MDMs) were utilized as human macrophage
    models to investigate the contribution of P2X4 by means of Ca2+ measurements,
    mRNA expression analysis and cytokine secretion assays. A side-by-side
    comparison study of MDM generated through stimulation with either GM-CSF (GMMDM)
    or M-CSF (M-MDM) illustrated that P2X4 has a bigger contribution towards
    ATP-evoked Ca2+ responses in GM-MDM cells. In GM-MDM cells, P2Y11 and P2Y13
    activation both contributed towards the amplitude and sustained phase of response,
    while P2X4, but not P2X1 or P2X7, activation contributed towards the sustained
    phase of ATP-evoked Ca2+ response. Employment of a cytokine and chemokine
    mRNA profiler array in GM-MDM revealed that 100 μM ATP induced transforming
    growth factor-b2 (TGF-b2) and C-X-C motif chemokine 5 (CXCL5). Selective
    antagonism of P2X4 with PSB-12062 positively modulated ATP-mediated induction
    of TGF-b2 gene expression while it inhibited ATP-mediated induction of CXCL5
    gene expression. Although the effect on TGF-b2 was not translated at a protein
    level, PSB-12062 inhibited ATP-mediated induction of CXCL5 protein synthesis and
    secretion. Reciprocally, positive allosteric modulation of P2X4 with ivermectin
    augmented ATP-mediated CXCL5 secretion. Inhibition of P2X7, P2Y11 or P2Y13 had
    no effect on CXCL5 secretion. Altogether, we have identified a role for P2X4
    activation in determining the duration of ATP-evoked intracellular Ca2+ response
    and stimulating induction and secretion of CXCL5 in human primary macrophage.

    Item Type: Thesis (Doctoral)
    Faculty \ School: Faculty of Science > School of Biological Sciences
    Depositing User: Katie Miller
    Date Deposited: 12 Oct 2017 12:20
    Last Modified: 12 Oct 2017 12:20
    URI: https://ueaeprints.uea.ac.uk/id/eprint/65123

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