Immune response to HBV in Patients

Adam J. Gehring, Ph.D.Biology Lead

Toronto Centre for Liver DiseaseUniversity Health Network (UHN)

Assistant ProfessorDepartment of Immunology

University of Toronto

Adaptive Immune Response to HBV

Acute/ResolvedRobust, coordinated adaptive immunity1. CD8 T cells mediate clearance of infected cells2. B cells - anti-HBs marker of resolution 3. CD4 T helper cells support CD8 & B cells

ChronicWeak Adaptive Immune response1. Low T cell frequency2. Lack of effective antibodies

X XX

T

T

TT

T

B B

T cell responses do not correlate with clinical stages• Arbitrary definitions and many patients = indeterminate

Profile of the HBV-specific T cell Response in Chronic HBV

Park 2015 Dec;150(3):684–5.Kennedy Gastroenterology. 2012 Sep;143(3):637–45.

Age may be better correlation of T cell immunity• Higher T cell frequency detectable in younger patients• Lower PD-1 expression

T cell PD-1

Pallett, J. Exp Med. 2017 Jun 5;214(6):1567–80. Tan J. Virol. 2008 Oct 24;82(22):10986–97.

Variation in T cell repertoire• Age of patients alters antigen-specific repertoire• Different Genotypes/HLA profiles elicit different T cell repertoires• Important for measuring immunity• Designing vaccines

Profile of the HBV-specific T cell Response in Chronic HBV

T cells in the liver do not equal T cells in the blood• Different phenotype• Different functional profile• Different transcription factor profile

Total T cells HBV-specific T cells

Blood

Liver

Patients who lose HBsAg have higher T cell frequency• HBsAg loss on nuc treatment shows T cell recovery

• almost to level of acute response• T cell response in spontaneous clearance is higher than untreated• Cross-sectional study – chicken & egg?

Profile of the HBV-specific T cell Response in Chronic HBV

Boni, Gastroenterology. 2012 Oct;143(4):963–9.

Hepatotropic virus Liver is generally a tolerizing organ

o Hepatocyte/LSEC Antigen presentation = bad for primingo Suppressive Dendritic cellso High IL-10, TGF-β, PD-L1, enzymes degrading essential amino

acids, hypoxia

Hepatitis B Virus Immune Evasion/Exhaustion

High Antigen burdenHigh viral load High viral antigen

HBsAg up to 1 mg/ml in serumHBc-related Ag = ?

Constant presentation?Hepatocytes, LSEC, Periphery?

Inhibitory receptors often co-expresseda. Nebbia, PLoS ONE 2012; 7: e47648. b. Boni, J Virol 2007; 81: 4215–4225. c. Schurich Hepatology. 2011; 53: 1494–1503d. Bengsch, J. Hepatol. 2014 Dec;61(6):1212–9e. Fisicaro Gastroenterology. 2010 Feb;138(2):682–93

Significant mitochondrial dysfunction• Impairs T cell functionality• Antioxidants restore T cell functionality

a. Fisicaro Nat Med. 2017 Feb 6;23(3):327–36.

Active elimination of T cellsActivation induced apoptosis

a. Lopes J. Clin. Invest. 2008 May 1;118(5):1835–45

NK-TRAIL mediated killing of T cellsa. Peppa J. Exp Med. 210, 99–114 (2013).

Specific Mechanisms Suppressing HBV-specific T cells

Non-specific Mechanisms Suppressing HBV-specific T cell Function in chronic HBV

Arginase elevated in HBV patients• Correlates with ALT level• Suppresses T cell proliferation & function

a. Sandalova. Gastro. 2012 Jul;143(1):78–87.e3.b. Das. J. Exp Med. 2008 Aug 11;205(9):2111–24

Myeloid Derived Suppressor Cells (MDSC)• Produce Arginase and IL-10• Suppress T cell expansion

a. Pallett, Nat Med. 2015 Jun;21(6):591–600.

Regulatory cells – Treg & Breg• frequency correlates with ALT• produce IL-10• Depletion in vitro can enhance CD8 expansion

a. Das, J. Immunol. 2012 Oct 4;189(8):3925–35b. Xu, J. Immunol. 2006 Jul 1;177(1):739–47

Tregs Bregs

Acute/ResolvedRobust, coordinated adaptive immunity1. CD8 T cells mediate clearance of infected cells2. B cells - anti-HBs marker of resolution 3. CD4 T helper cells support CD8 & B cells

ChronicWeak Adaptive Immune response1. Low T cell frequency2. Lack of effective antibodies

X XX

T

T

TT

T

B B

Adaptive Immune Response to HBV- What About B Cells? -

Bertoletti, J. Hepatol. 2016 Apr;64(1 Suppl):S71–83. Rehermann, Nature Medicine 19, 859–868 (2013)

Adaptive Immune Response to HBV- What About B Cells? -

Detection of the HBV antibody response• Antigen > Immune Complexes > anti-HBs• Immune complexes found in >90% of acute patients• memory anti-HBs-specific B cells detectable by elispot

• after resolution• after vaccination

Madaliński, Clin & Exp Immun, 1979 Jun;36(3):371–8. Pernice, Clin & Exp Immun, 1979 Aug;37(2):376–80. Böcher, Hepatology, 2000 Feb 1;31(2):480–7. Vanwolleghem, Hepatology. 2015 Jul;62(1):87–100.

Memory anti-HBs-specific B cells difficult to detect • Fewer immune complexes in chronic patients

• mainly patients with active disease• Correlates with activated B cell profile in patients with

active disease • IgG subclasses may be associated with better control

B

Activated

Dusheiko, J. Clin. Invest. 1983 May;71(5):1104–13. Barnaba, Clin & Exp Immun. 1985 May;60(2):259–66. Böcher, Clin & Exp Immun,1996 Jul 1;105(1):52–8.

Oliviero, J. Hepatol. 2011 Jul;55(1):53–60.Rath, Clin & Expl Immun. 1988 Apr;72(1):164–7Gregorek, J. Hepatol. 2005 Apr;42(4):486–90.

Complexity of the Innate Immune Response to HBV

Arguably more complex than the T cell responseCD4 CD8NK

γδ T cell

MAIT

MN/MO

DC

Innate effectors• NK cells, MAIT cells, γδ T cells• Innate effectors can be negative regulators in chronic HBV patients• Little data on their role in recognizing/eliminating infected hepatocytes

Myeloid Cells• Dendritic Cells, Monocytes, Macrophages• Antigen presentation• Cytokine production

Parenchymal cell responses • Hepatocytes, Endothelial Cells, Stellate cells

Human innate immune response studied mainly in context of pathogenesis of chronic HBV• Limited data comparing innate immunity in acute - resolved – chronic HBV patients

Innate Immune Response in Chronic HBV

Vertical transmission accounts for a majority of chronically infected patients

No acute response to HBV because virus is always present • Innate immune system is exposed to HBV before birth

Hong. Nat Comms 6, 1–12 (2015).

NK cell IFN-γ production suppressed• Related to IL-10• Especially in hepatitis patients

Peppa, PLoS Pathog. 2010 Dec 16;6(12):e1001227.

Gehring J Clin Invest. 2013 Sep 3;123(9):3766-76 Boltjes PLoS ONE. 2014;9(5):e97006.

Myeloid cell function in chronic HBVDendritic cell • function highly variable• Inhibited, activated, restored with nucleoside analogues

Monocytes• Contain HBsAg in vivo• No evidence of altered stimulatory capacity • Intact cytokine production

TNF-α

Alterations in the Innate Immune Response to HBV

Caveats of myeloid cell analysis• Short-lived compared to T & B cells• Spend few days in circulation

• Susceptible to environmental changes• Bone marrow alteration?

Dapi HBsAg

Innate cells dominate the immune composition of the liver

Innate Immune Response in Chronic HBV

(NK/γδ/MAIT)

Lymphocytes

Blood

(NK/γδ/MAIT)Liver Liver

Myeloid Cells

Blood

Pattern Recognition receptors

Phase I/II Clinical Trials• TLR-7• TLR-8• Rig-I

Pre-clinical• STING• Inactivated viruses (PPOV)

Innate Targets for Immunomodulatory Drug Development

Induce innate/antiviral cytokine production• Cytokines: IL-1α, IL-1β, IL-10, IL-6, IL-12, IL-18, TNF-α, IFN-α, IFN-λ• Chemokines: CXCL-8, -9, -10, Mip1a, Mip1B, MCP-1

Gehring, Best Pract Res Clin Gastroenterol. 2017 Jun;31(3):337-345

Summary

HBV-Specific T cell response• Not significantly different across different phases of HBV• Repertoire varies by genotype, HLA profile and localization• Multiple specific and non-specific mechanisms maintaining the exhausted state

B cell response• Top level data – more work is needed• Memory B cells are detectable in resolved/vaccinated• So far, difficult to detect in chronic patients – need better tools• activated profile during active disease: meaning?

Innate Immunity• Needed to enhance T cell immunity = antigen presentation• Significant antiviral potential if properly harnessed• Reduced NK cell function in chronic HBV• Negatively regulates T cell immunity = MDSC, NK-TRAIL