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Cytokine secretion from monocytes persists differentially after activator removal—One mechanism of long‐term biological response to implants
Author(s) -
Messer R. L. W.,
Lewis J. B.,
Wataha J. C.,
Adams Y.,
Tseng W. Y.
Publication year - 2007
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.30766
Subject(s) - cytokine , secretion , inflammation , immunology , tumor necrosis factor alpha , activator (genetics) , mediator , wound healing , medicine , microbiology and biotechnology , biology , receptor
Biomedical implants significantly improve the quality of life in an ever‐increasing number of patients. However, inflammation of tissues around implants remains a long‐term, post‐placement sequelae that may contribute to implant failure. Infection‐mediated failure is partly a consequence of inappropriate host response and chronic inflammation, and is mediated primarily by the secretory products of monocytes and macrophages. Although the secretion of inflammatory mediators from activated monocytes is well characterized, the resolution of mediator levels post‐activation is relatively unstudied. The current study defines the time course of cytokine secretion by activated human monocytes after the activator has been removed. THP1 human monocytes were activated by LPS, and cytokine secretion was monitored over time after LPS removal using enzyme‐linked immunosorbent assays (TNFα or IL8) or a cytokine array. The release of cytokines was compared with conditions without LPS removal. As expected, secretion of nearly all cytokines was reduced when LPS was removed, but the amount of the reduction was highly cytokine‐dependent. Furthermore, levels of cytokines were stable in medium alone but not in cell‐culture, suggesting an active process to either degrade or internalize secreted cytokines. Our results are consistent with clinical experience that inflammation resolves rapidly after treatment to remove bacteria or inflamed tissue. However, the differential cytokine regulation indicates a sophisticated coordination of cytokine levels probably associated with management of the wound healing response after removal of the bacterial insult. This wound healing response is one critical component of the long‐term success of biomedical implants. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007