title: Early effects of Staphylococcus aureus biofilm secreted products on inflammatory responses of human epithelial keratinocytes.
abstract: BACKGROUND
  Chronic wounds such as diabetic foot ulcers, pressure ulcers, and venous leg ulcers contribute to a considerable amount of mortality in the U.S. annually. The inability of these wounds to heal has now been associated with the presence of microbial biofilms. The aim of this study was to determine if products secreted by S. aureus biofilms play an active role in chronic wounds by promoting inflammation, which is a hallmark of chronic wounds.
  
  
  METHODS
  In vitro experiments were conducted to examine changes in gene expression profiles and inflammatory response of human epithelial keratinocytes (HEKa) exposed to products secreted by S. aureus grown in biofilms or products secreted by S. aureus grown planktonically.
  
  
  RESULTS
  After only two hours of exposure, gene expression microarray data showed marked differences in inflammatory, apoptotic, and nitric oxide responses between HEKa cells exposed to S. aureus biofilm conditioned media (BCM) and HEKa cells exposed to S. aureus planktonic conditioned media (PCM). As early as 4 hours post exposure, ELISA results showed significant increases in IL-6, IL-8, TNFα, and CXCL2 production by HEKa cells exposed to BCM compared to HEKa cells exposed to PCM or controls. Nitric oxide assay data also showed significant increases in nitric oxide production by HEKa cells treated with BCM compared to HEKa cells treated with PCM, or controls.
  
  
  CONCLUSIONS
  Taken together, these results support and extend previous findings that indicate products secreted by S. aureus biofilms directly contribute to the chronic inflammation associated with chronic wounds.
authors.affiliation: Biology Department, University of Central Oklahoma, 100 North University Drive, Edmond, Oklahoma 73034, USA.
authors.forename: Amy
authors.initials: A
authors.lastname: Tankersley
authors.affiliation: Microarray Research Facility, Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA.
authors.forename: Mark Barton
authors.initials: MB
authors.lastname: Frank
authors.affiliation: Microarray Research Facility, Arthritis and Clinical Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA.
authors.forename: Melissa
authors.initials: M
authors.lastname: Bebak
authors.affiliation: Biology Department, University of Central Oklahoma, 100 North University Drive, Edmond, Oklahoma 73034, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Brennan
keywords: Biofilms; Gene expression microarray; Inflammation; Keratinocytes; Nitric oxide; Staphylococcus aureus