Expression of P2X7 ATP Receptor Mediating the IL8 and CCL20 Release in Human Periodontal Ligament Stem Cells

Abstract

ATP is released by human periodontal ligament cells (hPDLCs) and has been shown to regulate PDL regeneration and responses to mechanical stress through activation of P2Y receptors. This nucleotide, however, has also been reported to trigger the pro-inflammatory cascade by inducing the maturation and/or release of chemokines/cytokines from various cell types mainly via P2X7 receptors. Much less is known on the possible role of ATP in stem cells deriving from PDL (hPDLSCs) which are considered to be a promising tool for cell-based therapy to restore lesions. Given the role played by P2X7 in pathophysiological conditions, in this study we investigated the expression of P2X7 ATP receptors in hPDLSCs. The results obtained showed that hPDLSCs express P2X7 receptors evaluated by means of cytofluorimetric, immunohistochemistry, reverse transcriptase-PCR, and Western blot analyses. P2X7 ligation by 2',3'-(benzoyl-4-benzoyl)-ATP (BzATP), a specific receptor agonist, was followed by an increase in intracellular Ca2+ and in the uptake of ethidium bromide. These effects were dramatically reduced by oxidized ATP (oATP), the P2X7 irreversible inhibitor, suggesting that the P2X7 is the functional receptor involved. At 24 h treatment of hPDLSCs with BzATP it enhanced the release of the pro-inflammatory agents IL8 and CCL20, without influencing cell viability. These effects were counteracted by pre-treating the cells with oATP or with A-740003, a selective and potent P2X7 competitive antagonist. Collectively, these results indicated that extracellular ATP mediate a pro-inflammatory response via P2X7 receptors in hPDLSCs opening a further approach to control hPDLSCs behavior in their possible application as therapeutic tool.

Extracellular ATP and other nucleotides—ubiquitous triggers of intercellular messenger release

“…Human periodontal ligament stem cells (hPDLCs) released CXCL8 following extended stimulation of the P2X7R, involving an increase in intracellular Ca 2+ concentrations [147]. CXCL8 release from human neutrophils was stimulated synergistically by toll-like receptors and P2Rs.…”

“…Chemokine production was mediated via both calcineurindependent nuclear factor of activated T cells (NFAT) and PKC/MAPK signaling pathways. Similar to CXCL8, stem cells derived from human periodontal ligament cells released CCL20 (also macrophage inflammatory protein-3, MIP3A), a chemoattractant for lymphocytes and neutrophils, through P2X7R activation [147].…”

P2X1, P2X4, and P2X7 Receptor Knock Out Mice Expose Differential Outcome of Sepsis Induced by α-Haemolysin Producing Escherichia coli

“…In terms of infection, ATP is a well-recognized signaling molecule released at sites of inflammation/cell injury, and plays a central role in immune cell migration, chemotaxis, and cytokine release (Junger, 2008; Bours et al, 2011). In particular, the P2X 7 receptor has attracted considerable attention for its importance in immune cell communication (Di Virgilio and Vuerich, 2015), release of pro-inflammatory cytokines (Suzuki et al, 2004; Clark et al, 2010; Shieh et al, 2014; Trubiani et al, 2014), and recruitment of macrophages and lymphocytes (Moncao-Ribeiro et al, 2011; da Silva et al, 2013). Therefore, the P2X 7 has emerged as a potential anti-inflammatory therapeutic target.…”

Secreted adenosine triphosphate from Aggregatibacter actinomycetemcomitans triggers chemokine response

“…Furthermore, bacterial eATP‐induced chemokine expression occurred in a PLC‐independent manner, indicating a role for the P2X receptor. A recent report showed that ATP induced the expression of chemokine in human periodontal ligament stem cells (Trubiani et al ., ). Similarly, we found that bacterial eATP P2X7 receptor was important in sensing bacterial eATP to elicit a chemokine response.…”