Interleukin-1alpha and interleukin-6 enhance the antibacterial properties of cultured composite keratinocyte grafts.
OBJECTIVE
To determine whether the antibacterial properties of cultured composite keratinocyte grafts can be enhanced by cytokines that stimulate the innate immune response.


BACKGROUND
Use of composite grafts of cultured keratinocytes has been limited because of their susceptibility to burn wound microorganisms as a result of their lack of a vasculature and immune cells when transplanted. Moreover, use of topical antimicrobial agents is limited with these composite grafts because of cytotoxic effects. Keratinocytes, like all epithelial cells in the body, maintain a natural defense mechanism called the innate immune system. Some components of this system can be induced by cytokines.


METHODS
The innate immune response of cultured composite keratinocyte grafts treated with various cytokines was assessed indirectly by measuring the levels of mRNA encoding antimicrobial peptides (human beta defensin-1 and -2, LL-37, and antileukoprotease) and antimicrobial proteins (lysozyme, bactericidal/permeability-inducing protein, and phospholipase A2) by reverse transcription-polymerase chain reaction and directly by measuring the ability of keratinocytes to inhibit the growth of added bacteria (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus).


RESULTS
Treatment with interluekin-1alpha increased mRNA levels of antimicrobial peptides in keratinocytes on plastic dishes and in composite grafts. Interleukin-6 increased mRNA levels of antimicrobial proteins in composite grafts only. When added to composite grafts, both cytokines increased antibacterial activity against E. coli, P. aeruginosa, and S. aureus. Moreover, interleukin-1alpha and interleukin-6 did not impair the formation of a differentiated epidermis in vitro or after transplantation of the composite grafts.


CONCLUSIONS
Treatment with interleukin-1alpha or interleukin-6 of cultured composite keratinocyte grafts stimulates the innate immune response of keratinocytes, enhances the antibacterial properties of these grafts, and may better prepare them to combat infections in contaminated burn wounds.
Erdag
Gulsun
G
Center for Engineering in Medicine and Surgical Services, Massachusetts General Hospital and Harvard Medical School, Shriners Hospital for Children, Boston, Massachusetts 02114, USA.
Morgan
Jeffrey R
JR
D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000276:immunology; D001419:Bacteria / Q000276:immunology; D001424:Bacterial Infections / Q000517:prevention & control*; D002056:Burns / Q000150:complications / Q000601:surgery*; D002102:Cadaver; D002478:Cells, Cultured; D003470:Culture Media; D003627:Data Interpretation, Statistical; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D015850:Interleukin-6 / Q000494:pharmacology*; D015603:Keratinocytes / Q000187:drug effects / Q000276:immunology* / Q000637:transplantation*; D008297:Male; D051379:Mice; D008819:Mice, Nude; D012313:RNA / Q000302:isolation & purification; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014946:Wound Infection / Q000517:prevention & control*
D023181:Antimicrobial Cationic Peptides; D003470:Culture Media; D007375:Interleukin-1; D015850:Interleukin-6; D012333:RNA, Messenger; D012313:RNA