title: Linoleate appears to protect against palmitate-induced inflammation in Huh7 cells.
abstract: BACKGROUND
  Polyunsaturated fatty acids (PUFAs) may protect against metabolic diseases. Although the benefits of the n-3 family of PUFA have been well investigated in nonalcoholic steatohepatitis (NASH), little is known about the effect of the n-6 family. This study examined the effect of linoleate, a member of the n-6 family, on regulation of the palmitate-induced inflammatory cytokine interleukin-8 (IL8) in hepatocytes.
  
  
  METHODS
  Huh7 cells and HepG2 cells were cultured with and without free fatty acid treatment (palmitate and linoleate, alone or in combination, 100-1000 μM). Inflammatory pathways, lipid accumulation, apoptosis and cell viability were monitored.
  
  
  RESULTS
  Dose- and time-related changes of IL8 mRNA expression were examined and 9 h treatment with 500 μM palmitate showed the greatest elevation of IL8. Co-treatment with 500 μM palmitate and 400 μM linoleate significantly suppressed IL8 production below that with palmitate alone in both cells (both mRNA and protein). A quantitative measurement for lipid accumulation showed no significant difference between palmitate-treated cells (1.69 ± 0.21), linoleate-treated cells (1.61 ± 0.16) and palmitate and linoleate-treated cells (1.73 ± 0.22, NS, n = 7). The co-treatment with 400 μM linoleate inhibited phospho-c-Jun N-terminal kinase (pJNK) activation and IkBα reduction caused by 500 μM palmitate treatment. Treatment with 400 μM linoleate alone led to IL8 production (5.48 fold change), similar to co-treatment, with no influence on the expression of pJNK/IkBα. The cell viability was similar between treatment with 500 μM palmitate and with both 500 μM palmitate and 400 μM linoleate, showing no significant changes in the expression of cleaved caspase-3.
  
  
  CONCLUSIONS
  Linoleate is a potent regulator of the proinflammatory cytokine IL8 via the JNK and nuclear factor kappa B pathways that are involved in the pathophysiology of NASH, suggesting a future recommendation of dietary management.
authors.affiliation: Department of Gastroenterology, Chiba University Graduate School of Medicine, 1-8-1, Inohana, Chuou-ku 260-8670, Chiba, Japan. maru-cib@umin.ac.jp.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Maruyama
authors.forename: Masanori
authors.initials: M
authors.lastname: Takahashi
authors.forename: Tadashi
authors.initials: T
authors.lastname: Sekimoto
authors.forename: Taro
authors.initials: T
authors.lastname: Shimada
authors.forename: Osamu
authors.initials: O
authors.lastname: Yokosuka
mesh_terms: D002460:Cell Line; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000139:chemically induced*; D016209:Interleukin-8 / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D019787:Linoleic Acid / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism; D010168:Palmitates / Q000633:toxicity*
chemical_list: D016209:Interleukin-8; D016328:NF-kappa B; D010168:Palmitates; D019787:Linoleic Acid; D048031:JNK Mitogen-Activated Protein Kinases