Endocannabinoid system activation contributes to glucose metabolism disorders of hepatocytes and promotes hepatitis C virus replication.
BACKGROUND
Insulin resistance is highly prevalent in patients with chronic hepatitis C (CHC) and to some extent accounts for fibrosis and reducing viral eradication. Activated cannabinoid 1 receptor (CB1R) signaling has been implicated in the development of phenotypes associated with insulin resistance and steatosis. We investigated the role of the endocannabinoid system in glucose metabolism disorders induced by hepatitis C virus (HCV) replication.


METHODS
Human hepatic stellate cells (HSC; LX-2 cells) were co-cultured with Huh-7.5 cells or Huh-7.5 cells harboring HCV replicon (replicon cells). Endocannabinoid levels were then measured by liquid chromatography/mass spectrometry. The expression of CB1R and its downstream glucose metabolism genes in hepatocytes were determined by real-time PCR and Western blot. Glucose uptake by hepatocytes and glucose production were measured. Glucose metabolism tests and measurements of HCV RNA levels and nonstructural protein 5A (NS5A) levels were taken after treatment with CB1R agonist arachidonyl-2-chloroethanolamide (ACEA) or antagonist AM251.


RESULTS
Compared to the co-culture with Huh-7.5 cells, the level of 2-arachidonoylglycerol (2-AG) and the CB1R mRNA and protein levels increased in the co-culture of LX-2 cells with replicon cells. The activation of CB1R decreased AMP-activated protein kinase (AMPK) phosphorylation, inhibited cell surface expression of glucose transporter 2 (GLUT2), and suppressed cellular glucose uptake; furthermore, it increased cyclic AMP response element-binding protein H (CREBH), then up-regulated phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) genes and down-regulated the glucokinase (GK) gene, thus promoting glucose production. Interferon treatment restored the aforementioned changes. CB1R antagonist improved glucose metabolism disorders by an increase in glucose uptake and a decrease in glucose production, and inhibited HCV replication.


CONCLUSIONS
HCV replication may not only increase the 2-AG content, but may also up-regulate the expression of CB1R of hepatocytes, then change the expression profile of glucose metabolism-related genes, thereby causing glucose metabolism disorders of hepatocytes and promoting HCV replication. Treatment with CB1R antagonist improved glucose metabolism disorders and inhibited viral genome replication.
Department of Infectious Diseases, Second Affiliated Hospital, Harbin Medical University, 246 Xuefu Road, Nangang District, Harbin 150086, China.
Li-Jie
LJ
Sun
Department of Infectious Diseases, Second Affiliated Hospital, Harbin Medical University, 246 Xuefu Road, Nangang District, Harbin 150086, China. Electronic address: yujianwu45@sina.com.cn.
Jian-Wu
JW
Yu
Department of Infectious Diseases, Second Affiliated Hospital, Harbin Medical University, 246 Xuefu Road, Nangang District, Harbin 150086, China.
Lin
L
Wan
Department of Infectious Diseases, Second Affiliated Hospital, Harbin Medical University, 246 Xuefu Road, Nangang District, Harbin 150086, China.
Xiao-Yu
XY
Zhang
Scientific Research and Experimental Center, Second Affiliated Hospital, Harbin Medical University, Harbin, China.
Yu-Guang
YG
Shi
Department of Infectious Diseases, Second Affiliated Hospital, Harbin Medical University, 246 Xuefu Road, Nangang District, Harbin 150086, China.
Mo-Yang
MY
Chen
D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism; D001095:Arachidonic Acids / Q000378:metabolism / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival; D018920:Coculture Techniques; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism; D063388:Endocannabinoids / Q000378:metabolism*; D016679:Genome, Viral; D044882:Glucose Metabolism Disorders / Q000473:pathology / Q000821:virology*; D051273:Glucose Transporter Type 2 / Q000235:genetics / Q000378:metabolism; D005952:Glucose-6-Phosphatase / Q000235:genetics / Q000378:metabolism; D005989:Glycerides / Q000378:metabolism; D016174:Hepacivirus / Q000302:isolation & purification* / Q000502:physiology; D055166:Hepatic Stellate Cells / Q000473:pathology / Q000821:virology; D019698:Hepatitis C, Chronic / Q000473:pathology; D022781:Hepatocytes / Q000378:metabolism / Q000821:virology*; D006801:Humans; D010766:Phosphorylation; D010880:Piperidines / Q000494:pharmacology; D053284:Polyunsaturated Alkamides / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000302:isolation & purification; D060888:Real-Time Polymerase Chain Reaction; D043884:Receptor, Cannabinoid, CB1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D015854:Up-Regulation; D014779:Virus Replication
D001095:Arachidonic Acids; D017362:Cyclic AMP Response Element-Binding Protein; D063388:Endocannabinoids; D051273:Glucose Transporter Type 2; D005989:Glycerides; D010880:Piperidines; D053284:Polyunsaturated Alkamides; D011720:Pyrazoles; D012333:RNA, Messenger; D012367:RNA, Viral; D043884:Receptor, Cannabinoid, CB1; C495680:SLC2A2 protein, human; C000594565:arachidonyl-2-chloroethanolamide; C103505:AM 251; C094503:glyceryl 2-arachidonate; D055372:AMP-Activated Protein Kinases; D005952:Glucose-6-Phosphatase; C078814:anandamide
CB1R; Cannabinoid 1 receptor; Endocannabinoids; Hepatic glucose metabolism; Hepatitis C virus