title: Alpha-calcitonin gene-related peptide can reverse the catabolic influence of UHMWPE particles on RANKL expression in primary human osteoblasts.
abstract: OBJECTIVE
  A linkage between the neurotransmitter alpha-calcitonin gene-related peptide (alpha-CGRP) and particle-induced osteolysis has been shown previously. The suggested osteoprotective influence of alpha-CGRP on the catabolic effects of ultra-high molecular weight polyethylene (UHMWPE) particles is analyzed in this study in primary human osteoblasts.
  
  
  METHODS
  Primary human osteoblasts were stimulated by UHMWPE particles (cell/particle ratios 1:100 and 1:500) and different doses of alpha-CGRP (10(-7 )M, 10(-9 )M, 10(-11 )M). Receptor activator of nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG) mRNA expression and protein levels were measured by RT-PCR and Western blot.
  
  
  RESULTS
  Particle stimulation leads to a significant dose-dependent increase of RANKL mRNA in both cell-particle ratios and a significant down-regulation of OPG mRNA in cell-particle concentrations of 1:500. A significant depression of alkaline phosphatase was found due to particle stimulation. Alpha-CGRP in all tested concentrations showed a significant depressive effect on the expression of RANKL mRNA in primary human osteoblasts under particle stimulation. Comparable reactions of RANKL protein levels due to particles and alpha-CGRP were found by Western blot analysis. In cell-particle ratios of 1:100 after 24 hours the osteoprotective influence of alpha-CGRP reversed the catabolic effects of particles on the RANKL expression.
  
  
  CONCLUSIONS
  The in-vivo use of alpha-CGRP, which leads to down-regulated RANKL in-vitro, might inhibit the catabolic effect of particles in conditions of particle induced osteolysis.
authors.affiliation: Department of Trauma Surgery, University of Duisburg-Essen, Hufelandstraße 55, 45147 Essen, Germany. kauther@uk-essen.de
authors.forename: Max D
authors.initials: MD
authors.lastname: Kauther
authors.forename: Jie
authors.initials: J
authors.lastname: Xu
authors.forename: Christian
authors.initials: C
authors.lastname: Wedemeyer
mesh_terms: D015153:Blotting, Western; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology*; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D008875:Middle Aged; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism*; D011095:Polyethylenes / Q000494:pharmacology*; D053245:RANK Ligand / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D011095:Polyethylenes; D053245:RANK Ligand; C505688:TNFSF11 protein, human; C111601:ultra-high molecular weight polyethylene; D015740:Calcitonin Gene-Related Peptide