Spred2 Deficiency Exacerbates D-Galactosamine/Lipopolysaccharide -induced Acute Liver Injury in Mice via Increased Production of TNF\u03b1

Xu Yang,Akihiro Matsukawa,Toshiaki Ohara,Teizo Yoshimura,Steven L Kunkel,Thar Htet San,Miwa Sato,Masayoshi Fujisawa,Tong Gao,Megumi Mino

doi:10.1038/s41598-017-18380-0

Xu Yang, Akihiro Matsukawa + Show 8 more

Open Access

https://doi.org/10.1038/s41598-017-18380-0

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Abstract

Acute liver injury (ALI) is characterized by hepatocyte damage and inflammation. In the present study, we examined whether the absence of Sprouty-related EVH1-domain-containing protein 2 (Spred2), a negative regulator of the Ras/Raf/ERK/MAPK pathway, influences ALI induced by D-galactosamine (D-GalN) and lipopolysaccharide (LPS). Compared to wild-type mice, Spred2−/− mice developed exacerbated liver injury represented by enhanced hepatocyte damage and inflammation. Enhanced ERK activation was observed in Spred2−/−-livers, and the MEK/ERK inhibitor U0126 ameliorated ALI. Hepatic tumour necrosis factor α (TNFα) and interleukin (IL)-1β levels were increased in Spred-2−/−-livers, and the neutralization of TNFα dramatically ameliorated ALI, which was associated with decreased levels of endogenous TNFα and IL-1β. When mice were challenged with D-GalN and TNFα, much severer ALI was observed in Spred2−/− mice with significant increases in endogenous TNFα and IL-1β in the livers. Immunohistochemically, Kupffer cells were found to produce TNFα, and isolated Kupffer cells from Spred2−/− mice produced significantly higher levels of TNFα than those from wild-type mice after LPS stimulation, which was significantly decreased by U0126. These results suggest that Spred2 negatively regulates D-GalN/LPS-induced ALI under the control of TNFα in Kupffer cells. Spred2 may present a therapeutic target for the treatment of ALI.

Highlights

Inactivation of MAPKAP kinase 2, a target of the p38-MAPK, protected mice from D-GalN/LPS-induced ALI13,14
Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining of liver sections at 5 h post D-GalN/LPS showed that apoptotic hepatocytes were increased in Sprouty-related EVH1-domain-containing protein 2 (Spred2)−/−-livers compared to in WT-livers (Fig. 2a)
Centrilobular necrosis with haemorrhage was improved by U0126 treatment in Spred2−/−-livers (Fig., 3c). These results indicate that hepatotoxicity was largely dependent on the ERK-MAPK pathway, and the augmented liver injury in Spred2−/− mice was due to upregulated ERK activation

Summary

Introduction

Inactivation of MAPKAP kinase 2, a target of the p38-MAPK, protected mice from D-GalN/LPS-induced ALI13,14. Robust ERK activation was observed in D-GalN/LPS-induced ALI15. Considering the involvement of ERK-MAPK in liver pathology, it is reasonable to speculate that ERK-MAPK plays a role in ALI. Dysregulation of ERK-MAPK may exacerbate D-GalN/LPS-induced ALI. The signalling pathway is counterbalanced by endogenous mechanism(s). As the ERK-MAPK pathway is activated in D-GalN/LPS-induced ALI, endogenous Spred proteins may be involved in regulating immune responses. We recently demonstrated that Spred[2] deficiency exacerbated LPS-induced lung inflammation with increased leukocyte infiltration by up-regulating the ERK-MAPK pathway[19]. We investigated the role of Spred[2] during the course of ALI. We demonstrated that Spred[2] controls the development of D-GalN/ LPS-induced ALI by negatively regulating the ERK-MAPK pathway

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