Increased lipopolysaccharide sensitivity in alcoholic fatty livers is independent of leptin deficiency and toll-like receptor 4 (TLR4) or TLR2 mRNA expression

Laszlo Romics, Pranoti Mandrekar, Karen Kodys, Arumugam Velayudham, Yvonne Drechsler, Angela Dolganiuc, Gyongyi Szabo

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Background: Both alcoholic (AFL) and nonalcoholic (NAFL) fatty livers show increased sensitivity to endotoxin-induced injury. Lipopolysaccharide (LPS) is recognized by toll-like receptor 4 (TLR4), whereas lipopeptide triggers TLR2 to induce common downstream activation of nuclear factor (NF)-κB and proinflammatory pathways that are activated in AFL and NAFL. Methods: Serum alanine aminotransferase (ALT), tumor necrosis factor (TNF)-α, and interleukin (IL)-6 levels; hepatic NF-κB activity; and expression of TLR2, TLR4, inducible nitric oxide synthase (iNOS), and heme oxygenase (HO)-1 mRNAs were investigated in lean and leptin-deficient ob/ob mice after LPS challenge in combination with acute or chronic alcohol feeding. Results: Increased LPS sensitivity in AFL and NAFL was characterized by elevated serum TNF-α and IL-6 induction. However, there was no difference in TLR2 and TLR4 mRNA levels between lean and ob/ob livers at baseline and after acute or chronic alcohol treatment. LPS increased TLR2, but not TLR4, mRNA levels in all groups. Chronic alcohol feeding and LPS increased serum ALT and TNF-α levels in lean but not in ob/ob mice compared with pair-fed controls. Hepatic NF-κB activation was increased in both ob/ob and lean mice after chronic alcohol feeding compared with pair-fed controls. Expression of iNOS, an inducer of oxidative stress, and HO-1, a cytoprotective protein, were higher in ob/ob compared with lean mice after chronic alcohol feeding. However, LPS-induced HO-1, but not iNOS, expression was attenuated in ob/ob compared with lean mice. Conclusion: These results imply that the increased sensitivity of AFL to LPS occurs without upregulation of TLR2 or TLR4 genes and may be related to an imbalance of pro-inflammatory/oxidative and cytoprotective mechanisms.

Original languageEnglish
Pages (from-to)1018-1026
Number of pages9
JournalAlcoholism: Clinical and Experimental Research
Volume29
Issue number6
DOIs
Publication statusPublished - Jun 1 2005

Keywords

  • Heme oxygenase-1
  • Inducible nitric oxide synthase
  • Interleukin-6
  • Nonalcoholic steatohepatitis
  • Nuclear factor-κB
  • Tumor necrosis factor-α

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Toxicology
  • Psychiatry and Mental health

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