The neuropeptide pituitary adenylate cyclase activating polypeptide modulates Ca(2+) and pro-inflammatory functions in human monocytes through the G protein-coupled receptors VPAC-1 and formyl peptide receptor-like 1.

摘要

In human neutrophils, the neuropeptide pituitary adenylate cyclase activating polypeptide (PACAP) acting via the G protein-coupled receptors vasoactive intestinal peptide/PACAP receptor 1 (VPAC-1) and formyl peptide receptor-like 1 (FPRL1) modulates Ca(2+) and pro-inflammatory activities. We evaluated in human monocytes the importance of the Ca(2+) signal and the participation of FPRL1 in PACAP-associated signaling pathways and pro-inflammatory activities. PACAP-evoked Ca(2+) transient involved both Ca(2+) influx and intracytoplasmic Ca(2+) mobilisation. This was pertussis toxin, protein kinase A and adenylate cyclase dependent indicating the participation of Galphai and Galphas with mobilisation of both InsP3 sensitive and insensitive stores. Intra- or extracellular Ca(2+) depletion resulted in the inhibition of PACAP-induced, Akt, ERK, p38 and NF-kappaB activations as well as a decrease in PACAP-associated reactive oxygen species (ROS) production and integrin CD11b membrane upregulation. The FPRL1 antagonist, Trp-Arg-Trp-Trp-Trp (WRW4), decreased PACAP-evoked Ca(2+) signal, Akt, ERK phosphorylation, ROS and CD11b upregulation without affecting p38 phosphorylation. NF-kappaB inhibitors prevented PACAP-induced Ca(2+) mobilisation. Monocytes pre-treatment with fMLP but not with LPS desensitised cells to the pro-inflammatory effects of PACAP. Thus, both intra- and extracellular Ca(2+) play a role in controlling pro-inflammatory functions stimulated by PACAP which acts through a VPAC-1, FPRL1/Galphai/PI3K/ERK pathway and a VPAC-1/Galphas/PKA/p38 pathway to fully activate monocytes.