Doxycycline reduces lipopolysaccharide-induced inflammatory mediator secretion in macrophage and ex vivo human whole blood models.
BACKGROUND
Tetracyclines have been extensively used as adjuncts in the treatment of some forms of periodontitis. The aim of this study was to evaluate the capacity of doxycycline to influence the secretion of inflammatory mediators in macrophage and ex vivo human whole blood models stimulated with periodontopathogen lipopolysaccharides (LPS).


METHODS
Monocyte-derived macrophages were treated with various concentrations of doxycycline prior to being stimulated with Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) LPS. The capacity of doxycycline to mediate the inflammatory response was also tested in an ex vivo whole blood model (whole blood isolated from periodontitis patients and healthy subjects) stimulated with Porphyromonas gingivalis LPS. The secretion of interleukin (IL)-1beta, -6, and -8 and tumor necrosis factor-alpha (TNF-alpha) in both models was assessed by enzyme-linked immunosorbent assays (ELISA). Changes in phosphorylation state of kinases induced by A. actinomycetemcomitans LPS and doxycycline in the macrophage model were characterized by a multiplex ELISA analysis.


RESULTS
The secretion of IL-1beta and -8 and TNF-alpha by macrophages decreased significantly (P <0.05) when they were pretreated with 2 microM doxycycline, whereas a concentration of 10 microM was required to significantly reduce IL-6 secretion. Pretreatment of macrophages with 10 microM doxycycline prior to A. actinomycetemcomitans LPS stimulation resulted in a marked decrease in the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 (-76%). In the whole blood model, doxycycline, more particularly at 10 microM, was also a potent inhibitor of the proinflammatory cytokine response.


CONCLUSIONS
These two models provided clear evidence that some of the clinically proven benefits of doxycycline may be related to its ability to regulate inflammatory mediator release by host cells.
Cazalis
Julia
J
Research Group in Oral Ecology, Faculty of Dentistry, Laval University, Quebec City, Quebec, Canada.
Bodet
Charles
C
Gagnon
Guy
G
Grenier
Daniel
D
D000328:Adult; D016976:Aggregatibacter actinomycetemcomitans; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D004318:Doxycycline / Q000494:pharmacology*; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000032:analysis* / Q000097:blood; D053583:Interleukin-1beta / Q000097:blood / Q000187:drug effects; D015850:Interleukin-6 / Q000032:analysis / Q000097:blood; D016209:Interleukin-8 / Q000097:blood / Q000187:drug effects; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008264:Macrophages / Q000187:drug effects*; D008297:Male; D008875:Middle Aged; D019950:Mitogen-Activated Protein Kinase 1 / Q000187:drug effects; D048052:Mitogen-Activated Protein Kinase 3 / Q000187:drug effects; D048056:Mitogen-Activated Protein Kinase 9 / Q000187:drug effects; D010518:Periodontitis / Q000097:blood / Q000382:microbiology; D010766:Phosphorylation; D016966:Porphyromonas gingivalis; D051057:Proto-Oncogene Proteins c-akt / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000187:drug effects
D000900:Anti-Bacterial Agents; D000893:Anti-Inflammatory Agents; D018836:Inflammation Mediators; D053583:Interleukin-1beta; D015850:Interleukin-6; D016209:Interleukin-8; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D048056:Mitogen-Activated Protein Kinase 9; C494918:AKT1 protein, human; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D004318:Doxycycline