title: Upregulation of chemokine CXCL1/KC by leptospiral membrane lipoprotein preparation in renal tubule epithelial cells.
abstract: We have previously shown that leptospiral membrane lipoprotein preparation (LMLP) extracted from pathogenic Leptospira santarosai serovar Shermani stimulates the secretion of pro-inflammatory mediators in renal tubule epithelial cells, and implicated its role in the initiation of tubulointerstitial nephritis. Renal tubulointerstitial injury is characterized by inflammatory cell infiltrate; however, the stimuli for leukocyte recruitment are not fully understood. Initial studies by cytokine protein array analysis revealed significant upregulation of neutrophil-chemoattractant keratinocyte-derived chemokine (CXCL1/KC) at nanogram range of LMLP stimulation in cultured murine proximal tubule cells (PTCs). As PTCs express Toll-like receptors (TLRs), this study investigated the roles of TLR signaling pathways in PTCs stimulated by LMLP and its relation to CXCL1/KC secretion. The LMLP stimulated the early secretion of CXCL1/KC and enhanced the level of TLR2 mRNA expression in PTCs through time- and dose-dependent effect. The LMLP-stimulated secretion of human growth-related oncogene alpha, a functional homolog to murine KC, in TLR-defective human embryonic kidney 293 cells transiently transfected with TLR2-expressing plasmids and the response was augmented by coexpression of TLR1 and TLR2. Moreover, silencing of TLR2, myeloid differentiation factor 88, and TNF receptor-associated factor 6 with specific small interfering RNA significantly reduces the response caused by LMLP in PTCs. The LMLP-stimulated CXCL1/KC secretion was also significantly reduced by pre-incubating PTCs with a specific p38 inhibitor. These results indicate that LMLP stimulates the production of CXCL1/KC to recruit polymorphonuclear neutrophils at the site of inflammation through a TLR2-mediated pathway in renal tubule cells.
authors.affiliation: Kidney Institute, and Department of Nephrology, Chang Gung Memorial Hospital and Chang Gung University, Taipei, Taiwan.
authors.forename: C-C
authors.initials: CC
authors.lastname: Hung
authors.forename: C-T
authors.initials: CT
authors.lastname: Chang
authors.forename: K-H
authors.initials: KH
authors.lastname: Chen
authors.forename: Y-C
authors.initials: YC
authors.lastname: Tian
authors.forename: M-S
authors.initials: MS
authors.lastname: Wu
authors.forename: M-J
authors.initials: MJ
authors.lastname: Pan
authors.forename: A
authors.initials: A
authors.lastname: Vandewalle
authors.forename: C-W
authors.initials: CW
authors.lastname: Yang
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology; D002460:Cell Line; D002478:Cells, Cultured; D019743:Chemokines, CXC / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000276:immunology* / Q000469:parasitology*; D007700:Kinetics; D007919:Leptospira / Q000737:chemistry; D008074:Lipoproteins / Q000276:immunology / Q000494:pharmacology*; D051379:Mice; D008822:Mice, Transgenic; D012333:RNA, Messenger / Q000032:analysis; D051195:Toll-Like Receptor 2 / Q000032:analysis / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D001425:Bacterial Outer Membrane Proteins; D019743:Chemokines, CXC; D008074:Lipoproteins; D012333:RNA, Messenger; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2