title: Leptin and Pro-Inflammatory Stimuli Synergistically Upregulate MMP-1 and MMP-3 Secretion in Human Gingival Fibroblasts.
abstract: BACKGROUND
  Gingival fibroblast-mediated extracellular matrix remodelling is implicated in the pathogenesis of periodontitis, yet the stimuli that regulate this response are not fully understood. The immunoregulatory adipokine leptin is detectable in the gingiva, human gingival fibroblasts express functional leptin receptor mRNA and leptin is known to regulate extracellular matrix remodelling responses in cardiac fibroblasts. We therefore hypothesised that leptin would enhance matrix metalloproteinase secretion in human gingival fibroblasts.
  
  
  RESULTS
  We used in vitro cell culture to investigate leptin signalling and the effect of leptin on mRNA and protein expression in human gingival fibroblasts. We confirmed human gingival fibroblasts expressed cell surface leptin receptor, found leptin increased matrix metalloproteinase-1, -3, -8 and -14 expression in human gingival fibroblasts compared to unstimulated cells, and observed that leptin stimulation activated MAPK, STAT1/3 and Akt signalling in human gingival fibroblasts. Furthermore, leptin synergised with IL-1 or the TLR2 agonist pam2CSK4 to markedly enhance matrix metalloproteinase-1 and -3 production by human gingival fibroblasts. Signalling pathway inhibition demonstrated ERK was required for leptin-stimulated matrix metalloproteinase-1 expression in human gingival fibroblasts; whilst ERK, JNK, p38 and STAT3 were required for leptin+IL-1- and leptin+pam2CSK4-induced matrix metalloproteinase-1 expression. A genome-wide expression array and gene ontology analysis confirmed genes differentially expressed in leptin+IL-1-stimulated human gingival fibroblasts (compared to unstimulated cells) were enriched for extracellular matrix organisation and disassembly, and revealed that matrix metalloproteinase-8 and -12 were also synergistically upregulated by leptin+IL-1 in human gingival fibroblasts.
  
  
  CONCLUSIONS
  We conclude that leptin selectively enhances the expression and secretion of certain matrix metalloproteinases in human gingival fibroblasts, and suggest that gingival fibroblasts may have an ECM-degrading phenotype during conditions of hyperleptinaemia (e.g., obesity, type 2 diabetes mellitus, exogenous leptin therapy).
authors.affiliation: Centre for Oral Health Research, Newcastle University, Newcastle upon Tyne, United Kingdom.|Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: Rachel C
authors.initials: RC
authors.lastname: Williams
authors.affiliation: Musculoskeletal Research Group, Newcastle University, Newcastle upon Tyne, United Kingdom.|Bioinformatics Support Unit, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Skelton
authors.affiliation: Department of Applied Sciences, Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Todryk
authors.affiliation: Musculoskeletal Research Group, Newcastle University, Newcastle upon Tyne, United Kingdom.|Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Rowan
authors.affiliation: Centre for Oral Health Research, Newcastle University, Newcastle upon Tyne, United Kingdom.|Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Preshaw
authors.affiliation: Centre for Oral Health Research, Newcastle University, Newcastle upon Tyne, United Kingdom.|Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors.forename: John J
authors.initials: JJ
authors.lastname: Taylor
mesh_terms: D005109:Extracellular Matrix / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D015870:Gene Expression; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D005881:Gingiva / Q000166:cytology*; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism* / Q000494:pharmacology; D007375:Interleukin-1 / Q000378:metabolism / Q000494:pharmacology; D020738:Leptin / Q000378:metabolism* / Q000494:pharmacology; D020781:Matrix Metalloproteinase 1 / Q000235:genetics / Q000378:metabolism*; D019278:Matrix Metalloproteinase 3 / Q000235:genetics / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D050791:STAT Transcription Factors / Q000378:metabolism; D059467:Transcriptome; D014746:Vimentin / Q000235:genetics / Q000378:metabolism
chemical_list: D018836:Inflammation Mediators; D007375:Interleukin-1; D020738:Leptin; D050791:STAT Transcription Factors; D014746:Vimentin; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases; D019278:Matrix Metalloproteinase 3; D020781:Matrix Metalloproteinase 1
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