title: Cathelicidin LL-37 induces time-resolved release of LTB4 and TXA2 by human macrophages and triggers eicosanoid generation in vivo.
abstract: In humans, LL-37 and eicosanoids are important mediators of inflammation and immune responses. Here we report that LL-37 promotes leukotriene B4 (LTB4) and thromboxane A2 (TXA2) generation by human monocyte-derived macrophages (HMDMs). LL-37 evokes calcium mobilization apparently via the P2X7 receptor (P2X7R), activation of ERK1/2 and p38 MAPKs, as well as cytosolic phospholipase A2 (cPLA2) and 5-lipoxygenase in HMDMs, leading to an early (1 h) release of LTB4. Similarly, TXA2 production at an early time involved the same signaling sequence along an LL-37-P2X7R-cPLA2-cyclooxygenase-1 (COX-1) axis. However, at later (6-8 h) time points, internalized LL-37 up-regulates COX-2 expression, promoting TXA2 production. Furthermore, intraperitoneal injection of mice with murine cathelicidin-related antimicrobial peptide (mCRAMP) induces significantly higher levels of LTB4 and TXA2 in mouse ascites rich in macrophages. Conversely, cathelicidin-deficient (Cnlp(-/-)) mice produce much less LTB4 and TXB2 in vivo in response to TNF-α compared with control mice. We conclude that LL-37 elicits a biphasic release of eicosanoids in macrophages with early, Ca(2+)-dependent formation of LTB4 and TXA2 followed by a late peak of TXA2, generated via induction of COX-2 by internalized LL-37, thus allowing eicosanoid production in a temporally controlled manner. Moreover, our findings provide evidence that LL-37 is an endogenous regulator of eicosanoid-dependent inflammatory responses in vivo.
authors.affiliation: Department of Medical Biochemistry and Biophysics, Division of Physiological Chemistry 2.
authors.forename: Min
authors.initials: M
authors.lastname: Wan
authors.affiliation: Institute for Cardiovascular Prevention, Ludwig Maximilians University, Munich, Germany; Department of Pathology, Academic Medical Center, Amsterdam, The Netherlands; and German Centre for Cardiovascular Research (DZHK), Munich Heart Alliance, Munich, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Soehnlein
authors.affiliation: Department of Medical Biochemistry and Biophysics, Division of Physiological Chemistry 2.
authors.forename: Xiao
authors.initials: X
authors.lastname: Tang
authors.affiliation: Department of Physiology and Pharmacology, and.
authors.forename: Anne M
authors.initials: AM
authors.lastname: van der Does
authors.affiliation: Department of Medical Biochemistry and Biophysics, Division of Molecular Neurobiology, Karolinska Institutet, Stockholm, Sweden;
authors.forename: Erik
authors.initials: E
authors.lastname: Smedler
authors.affiliation: Department of Medical Biochemistry and Biophysics, Division of Molecular Neurobiology, Karolinska Institutet, Stockholm, Sweden;
authors.forename: Per
authors.initials: P
authors.lastname: Uhlén
authors.affiliation: Department of Physiology and Pharmacology, and.
authors.forename: Lennart
authors.initials: L
authors.lastname: Lindbom
authors.affiliation: Department of Medical Biochemistry and Biophysics, Division of Physiological Chemistry 2.
authors.forename: Birgitta
authors.initials: B
authors.lastname: Agerberth
authors.affiliation: Department of Medical Biochemistry and Biophysics, Division of Physiological Chemistry 2, jesper.haeggstrom@ki.se.
authors.forename: Jesper Z
authors.initials: JZ
authors.lastname: Haeggström
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000172:deficiency / Q000502:physiology*; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism; D020013:Calcium Signaling; D054804:Cathelicidins / Q000172:deficiency / Q000502:physiology / Q000633:toxicity; D002478:Cells, Cultured; D015777:Eicosanoids / Q000096:biosynthesis*; D006801:Humans; D007249:Inflammation / Q000503:physiopathology; D007975:Leukotriene B4 / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010538:Peritonitis / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D054510:Phospholipases A2, Cytosolic / Q000378:metabolism; D010766:Phosphorylation; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational; D058486:Receptors, Purinergic P2X7 / Q000502:physiology; D011994:Recombinant Proteins / Q000633:toxicity; D013928:Thromboxane A2 / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000633:toxicity
chemical_list: D023181:Antimicrobial Cationic Peptides; D054804:Cathelicidins; D015777:Eicosanoids; D047428:Protein Kinase Inhibitors; D058486:Receptors, Purinergic P2X7; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D007975:Leukotriene B4; D013928:Thromboxane A2; D001094:Arachidonate 5-Lipoxygenase; D011451:Prostaglandin-Endoperoxide Synthases; D054510:Phospholipases A2, Cytosolic
keywords: P2X7R; antimicrobial peptides; inflammation; leukotriene; thromboxane