LysoPtdOH enhances CXCL16 production stimulated by LPS from macrophages and regulates T cell migration.

As a transmembrane chemokine, CXCL16 has been detected in various tissues and organs under normal and pathological conditions, it also plays an important role in macrophages/dendritic cells (DC) and T cell interactions and trafficking during inflammation and immune responses. LysoPtdOH, a bioactive lipid mediator has been indicated to regulate DC and epithelial functions during wound healing and inflammation responses. However, the direct link of CXCL16 expression with lysoPtdOH has not been established. Using monocyte-derived macrophages/DC (MoDC), we investigated the roles of lysoPtdOH in CXCL16 production and cell surface presentation. We found that macrophages/MoDC constitutively express and secrete CXCL16, lysoPtdOH significantly enhanced CXCL16 protein production stimulated with lipopolysaccharide (LPS) by more than twofold, which was reflected by increased mRNA transcription by 64-fold. Production of CXCL16 increased by lysoPtdOH and LPS from macrophages was inhibited around 70% by Pertussis toxin (G(i/o) specific inhibitor), exoC3 (Rho specific inhibitor), and pyrrolidine dithiocarbamate (the NF-kappaB-dependent pathway inhibitor) separately. LysoPtdOH treatment increased macrophages' chemotactic activity to activated T cells. The soluble form of CXCL16 produced by macrophages/MoDC was functionally chemoattractive to T cells.