Hepatitis C virus core and nonstructural proteins induce fibrogenic effects in hepatic stellate cells.
OBJECTIVE
The mechanisms by which hepatitis C virus (HCV) induces liver fibrosis are unknown. Hepatocytes secrete HCV proteins, which may interact with hepatic stellate cells (HSCs). Our aims were to investigate whether HCV proteins induce fibrogenic effects on HSCs.


RESULTS
Human-activated HSCs expressed messenger RNA (mRNA) for the putative HCV receptors CD81, LDL receptor, and C1q receptor as assessed by RT-PCR. Incubation of activated but not quiescent human HSCs with recombinant core and NS3 protein increased intracellular calcium concentration and reactive oxygen species production, as well as stimulated intracellular signaling pathways. Adenoviruses encoding core and nonstructural proteins (NS3-NS5) were used to express HCV proteins in HSCs. Expression of core protein increased cell proliferation in a Ras/ERK and PI3K/AKT dependent manner. In contrast, NS3-NS5 protein expression preferentially induced proinflammatory actions, such as increased chemokine secretion and expression of intercellular cell adhesion molecule type 1 (ICAM-1) through the NF-kappa B and c-Jun N-terminal kinase pathways. These effects were attenuated by antioxidants. Infection of freshly isolated rat HSCs with adenovirus-encoding core protein resulted in accelerated cell activation, as assessed by alpha-smooth muscle actin expression. Moreover, adenovirus-encoding core and NS3-NS5 proteins increased the secretion of bioactive TGF beta 1 and the expression of procollagen alpha1(I) in early cultured rat HSCs, as assessed by ELISA and RNase protection assay, respectively.


CONCLUSIONS
HCV core and nonstructural proteins regulate distinct biologic functions in HSCs. A direct interaction between HCV proteins and HSCs may contribute to HCV-induced liver fibrosis.
Bataller
Ramó
R
Department of Medicine and Biochemistry & Biophysics, University of North Carolina at Chapel Hill 27599-7038, USA. bataller@med.unc.edu
Paik
Yong-Han
YH
Lindquist
Jeffrey N
JN
Lemasters
John J
JJ
Brenner
David A
DA
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D018014:Gene Transfer Techniques; D016174:Hepacivirus / Q000378:metabolism*; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008103:Liver Cirrhosis / Q000209:etiology*; D009994:Osmolar Concentration; D051381:Rats; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors; D011991:Receptors, Virus / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D014758:Viral Core Proteins / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*
D018836:Inflammation Mediators; D017382:Reactive Oxygen Species; D011991:Receptors, Virus; D011994:Recombinant Proteins; D014758:Viral Core Proteins; D017361:Viral Nonstructural Proteins; D002118:Calcium