title: TLR-independent induction of human monocyte IL-1 by phosphoglycolipids from thermophilic bacteria.
abstract: The structures of phosphoglycolipids PGL1 and PGL2 from the thermophilic bacteria Meiothermus taiwanensis, Meiothermus ruber, Thermus thermophilus, and Thermus oshimai are determined recently (Yang et al. in J Lipid Res. 47:1823-1932, 2006). These bacteria belong to Gram-negative bacteria that do not contain lipopolysaccharide, but high amounts of phosphoglycolipids and glycoglycerolipids. Here we show that PGL1/PGL2 mixture (PGL1: PGL2 = 10:1 ~ 10:2) from M. taiwanensis and T. oshimai, but not T. thermophilus and M. ruber, up-regulate interleukin-1beta (IL-1beta) production in human THP-1 monocytes and blood-isolated primary monocytes. PGL2 was purified after phospholipase A2 hydrolysis of PGL1 in the PGL1/PGL2 mixture followed by column chromatography. PGL2 did not induce proIL-1 production, even, partially (35-40%) inhibited PGL1-mediated proIL-1 production, showing that PGL1 is the main inducer of proIL-1 production in PGL1/PGL2 mixture. The production of proIL-1 stimulated by phosphoglycolipids was strongly inhibited by specific PKC-alpha, MEK1/2, and JNK inhibitors, but not by p38-specific inhibitor. The intracellular calcium influx was involved in phosphoglycolipids-mediated proIL-1 production. Using blocking antibody and Toll-like receptor (TLR)-linked NF-kappaB luciferase assays, we found that the cellular receptor(s) for phosphoglycolipids on proIL-1 production was TLR-independent. Further, phosphoglycolipids isolated from T. thermophilus and M. ruber did not induce proIL-1 production, even though T. thermophilus possess more PGL1 than PGL2 (6:4). Specially, the fatty acid composition of phosphoglycolipids from both T. thermophilus and M. ruber consists of a low percentage of C15 (<10%) and a high percentage of C17 (>75%). It suggests, the C15 percentage of PGL may play a critical role in PGL-mediated proIL-1 induction.
authors.affiliation: Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan. yang111@gate.sinica.edu.tw
authors.forename: Feng-Ling
authors.initials: FL
authors.lastname: Yang
authors.forename: Kuo-Feng
authors.initials: KF
authors.lastname: Hua
authors.forename: Yu-Liang
authors.initials: YL
authors.lastname: Yang
authors.forename: Wei
authors.initials: W
authors.lastname: Zou
authors.forename: Yen-Po
authors.initials: YP
authors.lastname: Chen
authors.forename: Shu-Mei
authors.initials: SM
authors.lastname: Liang
authors.forename: Hsien-Yeh
authors.initials: HY
authors.lastname: Hsu
authors.forename: Shih-Hsiung
authors.initials: SH
authors.lastname: Wu
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D002460:Cell Line; D002469:Cell Separation; D002614:Chelating Agents / Q000494:pharmacology; D006017:Glycolipids / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D007375:Interleukin-1 / Q000096:biosynthesis*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D009000:Monocytes / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D010743:Phospholipids / Q000737:chemistry / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism; D011498:Protein Precursors / Q000096:biosynthesis; D051193:Toll-Like Receptors / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D002614:Chelating Agents; D006017:Glycolipids; D007375:Interleukin-1; D010743:Phospholipids; D011498:Protein Precursors; D051193:Toll-Like Receptors; D019000:Phosphotyrosine; D020928:Mitogen-Activated Protein Kinases