Osteopontin is induced by hedgehog pathway activation and promotes fibrosis progression in nonalcoholic steatohepatitis.

Nonalcoholic steatohepatitis (NASH) is a leading cause of cirrhosis. Recently, we showed that NASH-related cirrhosis is associated with Hedgehog (Hh) pathway activation. The gene encoding osteopontin (OPN), a profibrogenic extracellular matrix protein and cytokine, is a direct transcriptional target of the Hh pathway. Thus, we hypothesize that Hh signaling induces OPN to promote liver fibrosis in NASH. Hepatic OPN expression and liver fibrosis were analyzed in wild-type (WT) mice, Patched-deficient (Ptc(+/-) ) (overly active Hh signaling) mice, and OPN-deficient mice before and after feeding methionine and choline-deficient (MCD) diets to induce NASH-related fibrosis. Hepatic OPN was also quantified in human NASH and nondiseased livers. Hh signaling was manipulated in cultured liver cells to assess direct effects on OPN expression, and hepatic stellate cells (HSCs) were cultured in medium with different OPN activities to determine effects on HSC phenotype. When fed MCD diets, Ptc(+/-) mice expressed more OPN and developed worse liver fibrosis (P < 0.05) than WT mice, whereas OPN-deficient mice exhibited reduced fibrosis (P < 0.05). In NASH patients, OPN was significantly up-regulated and correlated with Hh pathway activity and fibrosis stage. During NASH, ductular cells strongly expressed OPN. In cultured HSCs, SAG (an Hh agonist) up-regulated, whereas cyclopamine (an Hh antagonist) repressed OPN expression (P < 0.005). Cholangiocyte-derived OPN and recombinant OPN promoted fibrogenic responses in HSCs (P < 0.05); neutralizing OPN with RNA aptamers attenuated this (P < 0.05). OPN is Hh-regulated and directly promotes profibrogenic responses. OPN induction correlates with Hh pathway activity and fibrosis stage. Therefore, OPN inhibition may be beneficial in NASH.

Syn WK ，Choi SS ，Liaskou E ，Karaca GF ，Agboola KM ，Oo YH ，Mi Z ，Pereira TA ，Zdanowicz M ，Malladi P ，Chen Y ，Moylan C ，Jung Y ，Bhattacharya SD ，Teaberry V ，Omenetti A ，Abdelmalek MF ，Guy CD ，Adams DH ，Kuo PC ，Michelotti GA ，Whitington PF ，Diehl AM ... -  《-》

NKT-associated hedgehog and osteopontin drive fibrogenesis in non-alcoholic fatty liver disease.

Syn WK ，Agboola KM ，Swiderska M ，Michelotti GA ，Liaskou E ，Pang H ，Xie G ，Philips G ，Chan IS ，Karaca GF ，Pereira Tde A ，Chen Y ，Mi Z ，Kuo PC ，Choi SS ，Guy CD ，Abdelmalek MF ，Diehl AM ... -  《-》

Osteopontin is a proximal effector of leptin-mediated non-alcoholic steatohepatitis (NASH) fibrosis.

Liver fibrosis develops when hepatic stellate cells (HSC) are activated into collagen-producing myofibroblasts. In non-alcoholic steatohepatitis (NASH), the adipokine leptin is upregulated, and promotes liver fibrosis by directly activating HSC via the hedgehog pathway. We reported that hedgehog-regulated osteopontin (OPN) plays a key role in promoting liver fibrosis. Herein, we evaluated if OPN mediates leptin-profibrogenic effects in NASH. Leptin-deficient (ob/ob) and wild-type (WT) mice were fed control or methionine-choline deficient (MCD) diet. Liver tissues were assessed by Sirius-red, OPN and αSMA IHC, and qRT-PCR for fibrogenic genes. In vitro, HSC with stable OPN (or control) knockdown were treated with recombinant (r)leptin and OPN-neutralizing or sham-aptamers. HSC response to OPN loss was assessed by wound healing assay. OPN-aptamers were also added to precision-cut liver slices (PCLS), and administered to MCD-fed WT (leptin-intact) mice to determine if OPN neutralization abrogated fibrogenesis. MCD-fed WT mice developed NASH-fibrosis, upregulated OPN, and accumulated αSMA+ cells. Conversely, MCD-fed ob/ob mice developed less fibrosis and accumulated fewer αSMA+ and OPN+ cells. In vitro, leptin-treated HSC upregulated OPN, αSMA, collagen 1α1 and TGFβ mRNA by nearly 3-fold, but this effect was blunted by OPN loss. Inhibition of PI3K and transduction of dominant negative-Akt abrogated leptin-mediated OPN induction, while constitutive active-Akt upregulated OPN. Finally, OPN neutralization reduced leptin-mediated fibrogenesis in both PCLS and MCD-fed mice. OPN overexpression in NASH enhances leptin-mediated fibrogenesis via PI3K/Akt. OPN neutralization significantly reduces NASH fibrosis, reinforcing the potential utility of targeting OPN in the treatment of patients with advanced NASH.

Coombes JD ，Choi SS ，Swiderska-Syn M ，Manka P ，Reid DT ，Palma E ，Briones-Orta MA ，Xie G ，Younis R ，Kitamura N ，Della Peruta M ，Bitencourt S ，Dollé L ，Oo YH ，Mi Z ，Kuo PC ，Williams R ，Chokshi S ，Canbay A ，Claridge LC ，Eksteen B ，Diehl AM ，Syn WK ... -  《-》

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

Syn WK ，Oo YH ，Pereira TA ，Karaca GF ，Jung Y ，Omenetti A ，Witek RP ，Choi SS ，Guy CD ，Fearing CM ，Teaberry V ，Pereira FE ，Adams DH ，Diehl AM ... -  《-》

Hedgehog-mediated epithelial-to-mesenchymal transition and fibrogenic repair in nonalcoholic fatty liver disease.

Syn WK ，Jung Y ，Omenetti A ，Abdelmalek M ，Guy CD ，Yang L ，Wang J ，Witek RP ，Fearing CM ，Pereira TA ，Teaberry V ，Choi SS ，Conde-Vancells J ，Karaca GF ，Diehl AM ... -  《-》