Up-Regulation of Nerve Growth Factor in Cholestatic Livers and Its Hepatoprotective Role against Oxidative Stress

Abstract

The role of nerve growth factor (NGF) in liver injury induced by bile duct ligation (BDL) remains elusive. This study aimed to investigate the relationship between inflammation and hepatic NGF expression, to explore the possible upstream molecules up-regulating NGF, and to determine whether NGF could protect hepatocytes from oxidative liver injury. Biochemical and molecular detection showed that NGF was up-regulated in cholestatic livers and plasma, and well correlated with systemic and hepatic inflammation. Conversely, systemic immunosuppression reduced serum NGF levels and resulted in higher mortality in BDL-treated mice. Immunohistochemistry showed that the up-regulated NGF was mainly localized in parenchymal hepatocytes. In vitro mechanistic study further demonstrated that TGF-β1 up-regulated NGF expression in clone-9 and primary rat hepatocytes. Exogenous NGF supplementation and endogenous NGF overexpression effectively protected hepatocytes against TGF-β1- and oxidative stress-induced cell death in vitro, along with reduced formation of oxidative adducted proteins modified by 4-HNE and 8-OHdG. TUNEL staining confirmed the involvement of anti-apoptosis in the NGF-exhibited hepatoprotection. Moreover, NGF potently induced Akt phosphorylation and increased Bcl-2 to Bax ratios, whereas these molecular alterations by NGF were only seen in the H2O2-, but not TGF-β1-treated hepatocytes. In conclusion, NGF exhibits anti-oxidative and hepatoprotective effects and is suggested to be therapeutically applicable in treating cholestatic liver diseases.

Nerve growth factor upregulates sirtuin 1 expression in cholestasis: a potential therapeutic target

“…Formalin-fixed and paraffin-embedded human and mouse livers were sectioned and used for hematoxylin and eosin and IHC staining, as previously described. 8 Deparaffinized and rehydrated sections were treated for antigen retrieval and incubated with primary antibodies at 4 °C overnight. Rabbit monoclonal antibodies purchased from Abcam (clone E51, Cambridge, MA, USA) were used to localize NGF (ab52918), TrkA (ab76291), p75NTR (ab52987) and the cleaved peptides of poly(ADP-ribose) polymerase (PARP).…”

“…Protein extraction, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunodetection were performed as previously described. 8 For immunodetection, antibodies against SIRT1 and the pro-peptide and active forms of caspase-3 and PARP, as well as the total and phosphorylated forms of Akt (Ser473; no. 4685), extracellular signal–regulated kinase 1/2 (ERK1/2) (Thr202/Tyr204; no.…”

“…Total RNA was extracted using TRIzol reagent (Invitrogen, Carlsbad, CA, USA) and was subjected to RT-qPCR detection using gene-specific primers ( Supplementary Table S1 ) and a previously described protocol. 8 …”

“…We previously demonstrated that nerve growth factor (NGF) was upregulated in cholestatic liver models and could protect hepatocytes against oxidative stress, 8 which is crucial for cholestatic liver injury. 9 Therefore, the identification and therapeutic targeting of NGF signaling should be considered as an alternative strategy to treat hepatolithiasis.…”

Neuroendocrine Changes in Cholangiocarcinoma Growth

“…NGF is a neuropeptide associated with cell growth and plays an important role with VEGF in cholangiocyte proliferation as mentioned [16]. During BDL, NGF expression is upregulated in cholangiocytes, leading to elevated ductular reaction and biliary inflammation in rodents [71,72]. CCA tumors express elevated levels of VEGF [47].…”