Increased expression of toll-like receptor-2 and -4 on leukocytes from patients with sepsis.
The reduced responsiveness of monocytes or granulocytes toward endotoxin (endotoxin tolerance) during sepsis may depend on Toll-like receptors (TLR). The expression of TLR-2 and TLR-4 was measured on neutrophils (PMN) and monocytes from patients with sepsis (n = 21) or healthy controls (n = 12). Leukocytes (1 x 10/mL) were incubated at 37 degrees C with or without a TLR-4 (LPS 1 microg/mL) or a TLR-2 ligand (MALP-2 2 nM). Surface expression of TLR-2 and TLR-4 at 0, 4, and 16 h was determined in FACS after staining with specific antibodies. The release of IL-8 and TNF-alpha was measured by ELISA. Freshly isolated PMN from patients with sepsis exhibited significantly (P < 0.05) higher mean fluorescence for TLR-2 (78.0 +/- 18.6) and TLR-4 (11.4 +/- 2.3) than controls (12.8 +/- 2.2 and 2.3 +/- 0.4). Similarly, monocytes from patients exhibited higher TLR-2 and TLR-4 expression (300.8 +/- 40.6 and 92.7 +/- 12.1) than cells from controls (149.5 +/- 27.1 and 52.2 +/- 7.6). In patients with sepsis, expression of TLR-2 and TLR-4 on PMN increased during 16 h of incubation (106.2 +/- 22.1 and 34.5 +/- 5.3), whereas it remained unchanged in controls (19.3 +/- 6.1 and 5.4 +/- 1.9). Incubation with LPS or MALP-2 had no effect on TLR-4 or TLR-2 expression in cells from either controls or patients. Despite increased TLR expression in cells from patients with sepsis, the endotoxin-induced release of TNF-alpha and IL-8 was indistinguishable from that in controls. Therefore, the endotoxin tolerance seen in patients with sepsis does not depend solely on TLR-2 or TLR-4 expression, and other mechanisms must be involved.
Härter
Luc
L
Division of Trauma Surgery, University Hospital Zurich, Zurich, Switzerland. luc.haerter@usz.ch
Mica
Ladislav
L
Stocker
Reto
R
Trentz
Otmar
O
Keel
Marius
M
D000328:Adult; D000368:Aged; D002469:Cell Separation; D016207:Cytokines / Q000378:metabolism; D004731:Endotoxins / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D007962:Leukocytes / Q000378:metabolism; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000378:metabolism; D008024:Ligands; D008297:Male; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D008875:Middle Aged; D009000:Monocytes / Q000378:metabolism; D009504:Neutrophils / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000096:biosynthesis*; D018805:Sepsis / Q000097:blood* / Q000235:genetics; D013997:Time Factors; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D016207:Cytokines; D004731:Endotoxins; D016209:Interleukin-8; D008024:Ligands; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha