1

Hepatitis C Around the World

Americas13.1 million

(1.7%)

Eastern Mediterranean

21.3 million(4.6%)

Africa31.9 million

(5.3%)

Southeast Asia32.3 million

(2.15%)

Europe8.9 million

(1.03%)

Western Pacific62.2 million

(3.9%)

World: 169.7 million (3.1%) prevalent cases

Reported rates of acute HCV infection by age group in Canada, 2004-2008

Male Female

• An estimated 242,500 people in Canada were infected with HCV as of December 2007 (0.7% of total population).

• In 2007, approximately 7,900 people in Canada were estimated to be newly infected with HCV.

• 21 percent of those infected with HCV are unaware of their infection.

Reported rate of acute HCV infection in Canada, 2004-2008

Epidemiology of HCV Infection in Canada(Public Health Agency of Canada)

HCV Infection: Transmission Routes

Distribution of mutually exclusive risk factors for newly-Acquired HCV

infection among cases with known risk factor

Canada 2004-2008

Blood to blood contact:

1. Shared needle in IV drug abusers.2. Vertical Transmission (Mother to Child).3. Percutaneous procedures. 4. Needle accident in health care providers.5. Contaminated blood products (rare)6. Others

Natural History of Hepatitis C

HCV Infection

Acute Hepatitis

Chronic Infection

Resolve Fulminant Hepatitis

HCCCirrhosis

Chronic Active Hepatitis

15-25% Rare75-85%

10-20% in 20 years

1-4%/year

Decompensated Cirrhosis, primary etiology of liver transplantation.

Bosch and others 1999, Sharma and Lok 2006

HCC, the third leading cause of cancer death worldwide.

Bosch and others 1999, Sharma and Lok 2006

Diagnostic tools for HCVScreening test: Enzyme Immunoassay (EIA), 3rd and 4th generation, Sensitive but low PPV

Confirmation tests:• Immunoblot analysis 3rd generation (RIBA), rarely used • Nucleic Acid Tests (NATs): Specific and Sensitive.

Scott JD, Gretch DR, JAMA 2008

Burlone, ME, et.al. J Gen Virol, 2009

HCV Life Cycle: Cell Entry

Lukavsky, PJ. Virus Research, 2009

HCV Life Cycle: RNA Translation

HCV Life Cycle: Assembly

HCV Life Cycle: Secretion as LVP

Immunopathogenesis of HCV Infection: Innate response of hepatocytes

Important ISGs that are activated by IFNβ:

Protein Kinase R (PKR): Phosphorylation of eIF2 and inhibition of HCV RNA translation.

Pflugheber, J., et al. PNAS, 2002.

ISG56: Phosphorylation of eIF3: and inhibition of HCV RNA translationHui, D.J., et al. JBC, 2003.

Adenosine Deaminase (ADAR1): converts adenosine residues into inosine residues in dsRNA strands, thereby mutating and destabilizing secondary viral RNA structures.

Taylor, D.R., et.al. J Virol, 2005.

Viperin: Crystallizes ER membrane, interferes with replication complex.Hinson and Cresswell 2009.

Rehermann, B. J Clin Invest, 2009

Innate Immune Cells:

NKT cells: 1. regulates the balance between Th1 and Th2 response and cytokine

production.2. In HCV infected liver they may secret cytokines negative effect on T cell

activation (IL-10, TGF-β).

NK Cells:3. Early in infection can kill the cells with high stimulatory/low inhibitory

signals.4. KIR2DL3 receptor and HLA-C1 are associated with very low inhibitory signal,

more likely to clear HCV. Khakoo, SI, et.al, science 2004

Dendritic Cells (DCs):5. bridging innate and adaptive immunity, by presenting Ag on their MHC II

priming adaptive immunity by activating CD4 T cells.6. Maturation and functional differentiation of conventional DCs are altered in

HCV infection, could possibly result in insufficient T cell priming and delayed HCV-specific T cell responses

Dolganiuc, A., et al. 2003. J. Immunol. 2003

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Antigen Presenting cells (e.g. DC)

Liver cells

HCV

CD8+ cytotoxic T cellTCR

CD8

MHC class I + peptide

Adaptive immunity: Key players

CD4+ helper cellTCR

B-cell

Antibodies

IFN-g

TH2 cytokines

IL-4, IL-10, IL-13

TH1 cytokines

(IFN-g, TNF-a)

1. Killing of infected cells

2. Neutralizing viral particles

3. Help

13Bowen D.G. and Walker CMNature 436, 946-952 (18 August 2005)

Patterns of Viral Replication and Immune responses in acute HCV

Transient control

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Mechanisms of CTL escape after mutation in cognate epitopes.

Bowen D and Walker CM, (2005). J. Exp. Med. 201:1709

15

Patterns of Immune responses in acute ->chronic HCV infections

16

Patterns of Immune responses in acute ->chronic HCV infections

Hepatic Fibrosis, The Main Pathology in HCV Induced Liver Injury

Bataller, R. Bremmer, DA. J Clin Invest, 2005

Hepatic Fibrosis, The Main Pathology in HCV Induced Liver Injury

Bataller, R. Bremmer, DA. J Clin Invest, 2005

Liver fibrosis:

Increased ECM depositionDecreased ECM degradationMMP (degrades), TIMP (inhibits MMP)

Decompensated Cirrhosis m

Compensated Cirrhosis m

Increasing Rate of Fibrosis

Time (Age)

Onset ofInfection

Progressive Fibrosis

HIV, HBV Co-InfectionHeavy Alcohol UseHemochromatosisWilson Diseaseα1 antitrypsin deficiency

Hepatic SteatosisAnd NASH

Acceleration of fibrosis

Progression of Fibrosis and CirrhosisIn HCV Infected Patients

40-86% of all HCV patients have hepatic steatosis.

Hepatic Steatosis and HCV

30-40% of HCV patients with steatosis do not have known risk factors such obesity, T2DM, etc…

Genotype dependent: more common andsevere in genotype 3.

Steatosis: abnormal retention of lipids within hepatocytes.

Hepatic Steatosis and HCVMetabolic VS Viral

Metabolic Type - genotype non 3

fatty liver is significantly reduced in sustained responders to antiviral treatment.

Steatosis α BMI

Viral-Type - genotype 3

Steatosis α Viral RNA

Possible Mechanisms of Steatosis:

1-Increased Lipogenesis

2-Decreased Lipid Oxidation

3-Decreased VLDL Secretion

.

Jensen M V et al. Am J Physiol Endocrinol Metab 2008;295:E1287-E1297

α-KGDH

Glucose

Fatty Acid Synthesis

Acetyl CoA Carboxylase (ACC)

Fatty Acid Synthase Complex (FAS)

Synthesis of Triacylglycerol

Acetyl CoA Carboxylase (ACC): The rate Limiting Enzyme

Substrate/product level regulation: activated with Citrate (Substrate), inhibited by Malonyl-CoA and Palmitoyl-CoA (Products)

Energy Level regulation: cAMP-PK and AMP-PK phosphorylates ACC and deactivates it. During fasting as ATP production declines AMP rises.

Hormonal regulation: Insulin (Feeding state hormone) activates ACC. Epinephrine and Glucagon (counter-regulatory, fasting state hormones) deactivates ACC.

Regulation of gene expression:

Cis Elemnent Trans Factor Effect

SRE SREBP Activates ACC and FAS

LXRE LXR Activated by Oxysterols

ChoRE ChoREBP Activates by high Cho Levels

Evidence of HCV Impact on Lipogenesis

Stimulation of SREBP by HCV GT2a (full ORF) and core/NS4B from GT3aWaris, G, et.al, Journal of Virology, 2007

NS2 of HCV H77 (GT1a) activates SREBP-1c results in increased FAS expression. Oem JK, et.al, J.Gen.Virol, 2007

NS4B from GT1b stimulates SREBP results in increased FAS expression. Park, CY, et.al, JBC, 2009

Transgenic mice with full length ORF of HCV GT1a stimulation of SREBP-1c and increase in transcription of FAS, SCD-1.

Lerat H, et.al, JBC, 2009Huh7 expressing HCV core from GT1b, increases ACC-1 activity and expression.

Fukasawa, M, et.al, Biol. Pharm Bulletin, 2006HCV GT3a and 1b core up-regulate FAS through SREBPs, GT3a>GT1b, Role of Phe 164 in activation of FAS.

Candice Jackel-Cram, et.al, Journal of Hepatology,2007Liver of CHC patients show increase in expression of LXRα, SREBP-1c and FAS.

Nakamuta, M. et.al, Int J Mol Med, 2009No Correlation between SREBP-1c and level of steatosis in liver of patients with HCV GT1 and 3

McPherson, S, et.al, Journal of Hepatology, 2008

Acetyl CoAMalonyl CoA-

Fatty Acid Oxidation Complex (FAS)

Evidence of HCV Impact on Fatty Acid Oxidation

Yasui K, et.al investigated the intrahepatic mRNA of genes important for lipid degradation in 100 HCV patients who lack metabolic factor for steatosis and compared the level between patients with steatosis vs non steatotic patients.

Yasui K, et.al, J Gastroenterol, 2009

Gene Symbol P value

PPARα 0.037

PPARγ 0.458

LXRα 0.001

RXRα 0.552

Gene Symbol P value

CPT1 0.204

SCAD <0.001

MCAD 0.059

LCAD 0.042

VLCAD 0.258

LBP 0.032

LCHAD 0.038

ACOX 0.040

CYP2E1 0.011

Nuclear ReceptorsFatty Acid Oxidation

VLDL Secretion

Evidence of HCV Impact on VLDL Secretion Pathway

Transgenic mice expressing HCV core have reduced MTP activity but not expressionPerlemuter, G, et.al, FASEB, 2002

Negative correlation between MTP mRNA&activity with HCV RNA levels in the liver of patients infected with HCV GT3 but not in non-GT3 HCV.

Mirandola S, et.al, Gastroenterology, 2006Hypobetalipoproteinemia in HCV GT3 patients and reversal after SVR.

Serfaty, L, et.al, Journal of Hepatology, 2001Hepatocellular fat accumulation and low serum cholesterol in patients infected with HCV-3a, reversal after SVR.

Hofer, H, et.al, Am J Gastroenterology, 2002

Why HCV inhibits MTP which is believe to be so critical for HCV life cycle????