title: Resistin promotes CCL4 expression through toll-like receptor-4 and activation of the p38-MAPK and NF-κB signaling pathways: implications for intervertebral disc degeneration.
abstract: This study was to investigate whether resistin induces the expression of chemokine ligand 4 (CCL4) during Intervertebral disc degeneration (IVDD) and whether toll-like receptor-4 (TLR-4) and the nuclear factor-κB (NF-κB) signaling pathway are involved in this process.
  
  
  
  The expression pattern of resistin and CCL4 in different degenerated human nucleus pulposus (NP) tissues were measured by quantitative reverse transcription-polymerase chain reaction (qPCR); Effect of resistin on the migration of macrophages was measured by cell migration assay. Resistin-induced CCL4 expression were analyzed by qPCR, Enzyme-linked immunosorbant assay (ELISA) and cell immunofluorescence. Involvement of TLR-4, p38-mitogen-activated protein kinase (p38-MAPK), and NF-κB signaling pathways were studied by small interfering RNA (siRNA) or Lenti-virus mediated knockdown, co-immunoprecipitation, and chromatin immunoprecipitation (ChIP) assay.
  
  
  
  Expression of resistin and CCL4 was elevated in degenerated NP tissue. Resistin promoted macrophage migration through CCL4 and its receptor. Expression of CCL4 was significantly increased by resistin treatment. The pharmacological inhibition or siRNA knockdown of TLR-4 blocked the resistin-induced CCL4 expression. Co-immunoprecipitation data confirmed the binding of resistin to TLR4. Pharmacological inhibition of the NF-κB and p38-MAPK signaling pathways attenuated the resistin-induced CCL4 expression. A ChIP assay and lentivirus mediated knockdown showed that resistin regulate CCL4 expression through p65.
  
  
  
  This study shows that resistin binds to TLR4 and increase the expression of CCL4 through p38-MAPK and NF-κB signaling pathways in NP cells, and this expression causes infiltration of macrophages. This study might provide a feasible therapeutic target for controlling the inflammatory response associated with IVDD.
authors.affiliation: Department of Spine Surgery, The 1st Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, PR China.
authors.forename: Z
authors.initials: Z
authors.lastname: Li
authors.affiliation: Guangdong Institute of Gastroenterology, Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The 6th Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, PR China.
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Spine Surgery, The 1st Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, PR China.
authors.forename: H
authors.initials: H
authors.lastname: Pan
authors.affiliation: Department of Orthopedic Surgery, Beijing Jishuitan Hospital, Peking University, Beijing, PR China.
authors.forename: H
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Spine Surgery, The 1st Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, PR China.
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Orthopedic Surgery, The 5th Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, PR China.
authors.forename: K
authors.initials: K
authors.lastname: Zhang
authors.affiliation: Department of Spine Surgery, The 1st Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, PR China.
authors.forename: H
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Spine Surgery, The 1st Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, PR China.
authors.forename: Z
authors.initials: Z
authors.lastname: Zheng
authors.affiliation: Department of Spine Surgery, The 1st Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, PR China. Electronic address: hippocratez@163.com.
authors.forename: H
authors.initials: H
authors.lastname: Liu
authors.affiliation: Department of Spine Surgery, The 1st Affiliated Hospital of Sun Yat-sen University, Guangzhou, Guangdong, PR China. Electronic address: zzuwjr@163.com.
authors.forename: J
authors.initials: J
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D015153:Blotting, Western; D054407:Chemokine CCL4 / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000378:metabolism; D055959:Intervertebral Disc Degeneration / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D016328:NF-kappa B / Q000378:metabolism*; D000070614:Nucleus Pulposus / Q000166:cytology / Q000378:metabolism; D051381:Rats; D060888:Real-Time Polymerase Chain Reaction; D052243:Resistin / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D051197:Toll-Like Receptor 4 / Q000378:metabolism*; D055815:Young Adult; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D054407:Chemokine CCL4; D016328:NF-kappa B; D052243:Resistin; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D048051:p38 Mitogen-Activated Protein Kinases
keywords: CCL4; Chemokine; Intervertebral disc; Nucleus pulposus; Resistin