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Accumulation of natural killer T cells in progressive nonalcoholic fatty liver disease.

ABSTRACT: Liver inflammation is greater in nonalcoholic steatohepatitis (NASH) than steatosis, suggesting that immune responses contribute to nonalcoholic fatty liver disease (NAFLD) progression. Livers normally contain many natural killer T (NKT) cells that produce factors that modulate inflammatory and fibrogenic responses. Such cells are relatively depleted in steatosis, but their status in more advanced NAFLD is uncertain. We hypothesized that NKT cells accumulate and promote fibrosis progression in NASH. We aimed to determine if livers become enriched with NKT cells during NASH-related fibrosis; identify responsible mechanisms; and assess if NKT cells stimulate fibrogenesis. NKT cells were analyzed in wildtype mice and Patched-deficient (Ptc(+/-)) mice with an overly active Hedgehog (Hh) pathway, before and after feeding methionine choline-deficient (MCD) diets to induce NASH-related fibrosis. Effects of NKT cell-derived factors on hepatic stellate cells (HSC) were examined and fibrogenesis was evaluated in CD1d-deficient mice that lack NKT cells. NKT cells were quantified in human cirrhotic and nondiseased livers. During NASH-related fibrogenesis in wildtype mice, Hh pathway activation occurred, leading to induction of factors that promoted NKT cell recruitment, retention, and viability, plus liver enrichment with NKT cells. Ptc(+/-) mice accumulated more NKT cells and developed worse liver fibrosis; CD1d-deficient mice that lack NKT cells were protected from fibrosis. NKT cell-conditioned medium stimulated HSC to become myofibroblastic. Liver explants were 2-fold enriched with NKT cells in patients with non-NASH cirrhosis, and 4-fold enriched in patients with NASH cirrhosis.Hh pathway activation leads to hepatic enrichment with NKT cells that contribute to fibrosis progression in NASH.

SUBMITTER: Syn WK

PROVIDER: S-EPMC2920131 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature

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Accumulation of natural killer T cells in progressive nonalcoholic fatty liver disease.

Syn Wing-Kin WK Oo Ye Htun YH Pereira Thiago A TA Karaca Gamze F GF Jung Youngmi Y Omenetti Alessia A Witek Rafal P RP Choi Steve S SS Guy Cynthia D CD Fearing Caitlin M CM Teaberry Vanessa V Pereira Fausto E L FE Adams David H DH Diehl Anna Mae AM

Hepatology (Baltimore, Md.) 20100601 6

<h4>Unlabelled</h4>Liver inflammation is greater in nonalcoholic steatohepatitis (NASH) than steatosis, suggesting that immune responses contribute to nonalcoholic fatty liver disease (NAFLD) progression. Livers normally contain many natural killer T (NKT) cells that produce factors that modulate inflammatory and fibrogenic responses. Such cells are relatively depleted in steatosis, but their status in more advanced NAFLD is uncertain. We hypothesized that NKT cells accumulate and promote fibros ...[more]

PMID: 20512988

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Project description:Nonalcoholic fatty liver disease (NAFLD), which occurs in approximately 17 to 40% of Americans, encompasses progressive stages of liver damage ranging from steatosis to nonalcoholic steatohepatitis (NASH). Inflammation and oxidative stress are known characteristics of NAFLD; however, the precise mechanisms occurring during disease progression remain unclear. The purpose of the current study was to determine whether the expression or function of enzymes involved in the antioxidant response, NAD(P)H:quinone oxidoreductase 1 (NQO1), glutathione transferase (GST), and glutamate cysteine ligase, are altered in the progression of human NAFLD. Human livers staged as normal, steatotic, NASH (fatty), and NASH (not fatty) were obtained from the Liver Tissue Cell Distribution System. NQO1 mRNA, protein, and activity tended to increase with disease progression. mRNA levels of the GST isoforms A1, A2, A4, M3, and P1 increased with NAFLD progression. Likewise, GST A and P protein increased with progression; however, GST M protein levels tended to decrease. Of interest, total GST activity toward the substrate 1-chloro-2,4-dinitrobenzene decreased with NAFLD progression. GSH synthesis does not seem to be significantly dysregulated in NAFLD progression; however, the GSH/oxidized glutathione redox ratio seemed to be reduced with disease severity, indicating the presence of oxidative stress and depletion of GSH throughout progression of NAFLD. Malondialdehyde concentrations were significantly increased with disease progression, further indicating the presence of oxidative stress. Nuclear immunohistochemical staining of nuclear factor E2-related factor 2 (Nrf2), an indicator of activation of the transcription factor, was evident in all stages of NAFLD. The current data suggest that Nrf2 activation occurs in response to disease progression followed by induction of specific Nrf2 targets, whereas functionality of specific antioxidant defense enzymes seems to be impaired as NAFLD progresses.

Dataset Information

Accumulation of natural killer T cells in progressive nonalcoholic fatty liver disease.

Publications

Accumulation of natural killer T cells in progressive nonalcoholic fatty liver disease.

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