7 We recently demonstrated in vitro that PAR2 activation on human monocytes enhances the suppressive effects of IFN-γ on influenza A virus replication.8 Moreover, in vivo studies have shown that a protective role of PAR2 against influenza infection is also mediated selleck compound by an IFN-γ-dependent mechanism.9 These studies revealed interplay between PAR2 activation and IFN-γ during the anti-viral response and raise the intriguing question

of whether PAR2 activation also contributes to anti-bacterial and immunomodulatory effects triggered by IFN-γ in monocytes and neutrophils. Human neutrophils and monocytes are not only ‘professional’ phagocytes, they are cells that, when activated, secrete different chemokines and cytokines. Stimulation of PAR2 agonist affects chemokine [IFN-inducible protein-10, interleukin-8 (IL-8)] and cytokine (IL-1β, IL-6) secretion by human neutrophils and monocytes.8,10 Among the chemokines secreted by neutrophils there is a molecule that appears to link neutrophils and monocytes during the time-delayed immune response to local infection. Monocyte chemoattractant protein-1 (MCP-1) is an essential mediator for monocyte and macrophage recruitment Metabolism inhibitor towards the site of infection.11,12 Neutrophils are a source of MCP-1 in time-delayed responses,13 and so may attract monocytes and macrophages. However,

MCP-1 is not only a chemotactic molecule for monocytes and macrophages, it also enhances the engulfment of apoptotic neutrophils (efferocytosis), thereby helping to resolve acute inflammation.14 In addition, MCP-1 is involved in fibroblast activation and influences collagen production, which makes MCP-1 an important participant in initial events during systemic scleroderma and skin fibrosis.15 Interferon-γ is known to increase the secretion of MCP-1 by human neutrophils 48 hr after stimulation.13 However, whether PAR2 agonists enhance MCP-1 release or

influence the IFN-γ-induced secretion of MCP-1 by human neutrophils has received little study. We therefore evaluated the contribution of PAR2 to the anti-microbial response of isolated human innate PLEK2 immune cells. We investigated whether PAR2 agonist acting alone affects the phagocytic and bactericidal activity of human neutrophils and monocytes. We also investigated whether IFN-γ enhances the effect of PAR2 agonist on the MCP-1 release by human neutrophils and monocytes, and examined the intracellular signalling molecules involved in the effects of PAR2 agonist on MCP-1 secretion. Human recombinant IFN-γ was purchased from TebuBio (Offenbach, Germany). Lipopolysaccharide (LPS) from Escherichia coli 055:B5 was purchased from Sigma (Munich, Germany; cat.#L2880). Human PAR2 activating peptide with the sequence trans-cinnamoyl-LIGRLO-NH2 (cAP) and reverse peptide with sequence trans-cinnamoyl-OLRGIL-NH2 (cRP) (Peptide Synthesis Facility, University of Calgary, Canada, Director: Dr Denis McMaster; the web page: http://www.