Peripheral blood mononuclear cell expression of toll-like receptors and relation to cytokine levels in cirrhosis.
Activation of macrophages by endotoxin is assumed responsible for increased circulating tumor necrosis factor alpha (TNF-alpha) and soluble TNF receptor (sTNFR) levels in cirrhosis. Relevant to this is expression of Toll-like receptor (TLR) 4 and TLR2, which is critically involved in production of TNF-alpha in response to endotoxin and Gram-positive microbial stimuli, respectively. The first studies on this in cirrhosis are reported here. In 36 cirrhotic patients and 32 controls, we measured (1) circulating endotoxin, TNF-alpha, and sTNFR levels; (2) peripheral blood mononuclear cell (PBMC) expression of TLR4 and TLR2, and (3) in vitro TNF-alpha production by PBMCs stimulated with endotoxin or Staphylococcus aureus enterotoxin B (SEB). PBMC expression of TLR2, circulating TNF-alpha levels, and in vitro TNF-alpha production were reassessed after supplementation with a synbiotic regimen known to increase intestinal levels of Gram-positive bacteria. Endotoxin, TNF-alpha, and sTNFR levels were significantly increased in cirrhosis. Endotoxin levels did not correlate significantly with other parameters. PBMC expression of TLR2 but not TLR4 was significantly up-regulated in cirrhosis and correlated significantly with serum TNF-alpha and sTNFR levels. In vitro TNF-alpha production by PBMCs stimulated by SEB was significantly blunted. Supplementation with the synbiotic regimen resulted in significant up-regulation of PBMC expression of TLR2. Serum TNF-alpha levels were further increased and in vitro TNF-alpha production further reduced in most patients. In conclusion, up-regulation of PBMC expression of TLR2 but not TLR4 occurs in cirrhosis, which implies, contrary to previous assumptions, an important stimulatory role for Gram-positive microbial components but not endotoxin. TLR2 likely contributes to increased circulating TNF-alpha and sTNFR levels in cirrhosis.
Riordan
Stephen M
SM
Gastrointestinal and Liver Unit, The Prince of Wales Hospital and University of New South Wales, Sydney, Australia. riordans@sesahs.nsw.gov.au
Skinner
Narelle
N
Nagree
Ammar
A
McCallum
Helen
H
McIver
Christopher J
CJ
Kurtovic
Jelica
J
Hamilton
John A
JA
Bengmark
Stig
S
Williams
Roger
R
Visvanathan
Kumar
K
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D029721:Drosophila Proteins; D004731:Endotoxins / Q000097:blood; D000068800:Etanercept; D005260:Female; D005765:Gastrointestinal Agents / Q000008:administration & dosage; D006094:Gram-Positive Bacteria; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D066298:In Vitro Techniques; D007792:Lactulose / Q000008:administration & dosage; D007963:Leukocytes, Mononuclear / Q000502:physiology*; D008103:Liver Cirrhosis / Q000097:blood* / Q000188:drug therapy / Q000276:immunology; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008875:Middle Aged; D019936:Probiotics / Q000008:administration & dosage; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018124:Receptors, Tumor Necrosis Factor / Q000097:blood*; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D029721:Drosophila Proteins; D004731:Endotoxins; D005765:Gastrointestinal Agents; D007074:Immunoglobulin G; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D018124:Receptors, Tumor Necrosis Factor; 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; D007792:Lactulose; D000068800:Etanercept