Lipoteichoic acid is a potent inducer of cytokine production in rat and human Kupffer cells in vitro.
BACKGROUND
Kupffer cells have been proposed to be a major cellular origin of pro-inflammatory mediators in sepsis. However, the cytokine response of Kupffer cells to gram-positive bacteria and their endotoxins peptidoglycan (PepG) and lipoteichoic acid (LTA) has never previously been studied.


METHODS
Primary cultures of rat and human Kupffer cells were exposed to live Staphylococcus aureus (S. aureus) (4.0 x 10(1) to 4.0 x 10(7) CFU/mL culture medium), as well as highly purified PepG and LTA (0-100 microg/mL). Lipopolysaccharide (LPS) at 1 microg/mL was used for control. In parallel experiments, whole blood obtained from the same rats was stimulated in a similar manner. Accumulation of the proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in plasma or culture supernatants were assessed by enzyme immuno assays. TNF-alpha and IL-6 mRNA were analyzed by real-time RT-PCR.


RESULTS
PepG and LTA, as well as live S. aureus, induced the production of TNF-alpha and IL-6 in Kupffer cells from both species in a time- and dose-dependent manner. Whereas PepG was a more potent inducer of TNF-alpha and IL-6 in whole blood, the opposite seemed to be the case in Kupffer cells. In fact, a 100-fold lower concentration of LTA (1 microg/mL) than of PepG (100 microg/mL) was sufficient to induce a substantial production of both TNF-alpha and IL-6 in the Kupffer cells. TNF-alpha and IL-6 mRNA were induced correspondingly.


CONCLUSIONS
Our results support the contention that gram-positive bacteria may activate cytokine production in Kupffer cells during bacteremia and suggest that LTA is important in this interaction.
Øverland
Gunhild
G
Institute for Surgical Research, Rikshospitalet University Hospital, Oslo, Norway.
Morath
Sigfried
S
Yndestad
Arne
A
Hartung
Thomas
T
Thiemermann
Christoph
C
Foster
Simon J
SJ
Smedsrød
Bård
B
Mathisen
Øystein
Ø
Aukrust
Pål
P
Aasen
Ansgar O
AO
Wang
Jacob E
JE
D000818:Animals; D016470:Bacteremia / Q000276:immunology; D004731:Endotoxins / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D015850:Interleukin-6 / Q000096:biosynthesis*; D007728:Kupffer Cells / Q000187:drug effects* / Q000276:immunology*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D023421:Models, Animal; D010457:Peptidoglycan / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013211:Staphylococcus aureus / Q000276:immunology*; D013682:Teichoic Acids / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*
D004731:Endotoxins; D015850:Interleukin-6; D008070:Lipopolysaccharides; D010457:Peptidoglycan; D013682:Teichoic Acids; D014409:Tumor Necrosis Factor-alpha; C009900:lipoteichoic acid