Immune reconstitution Anjie Zhen, PhD 8.6.2013

1. Immune reconstitutionAnjie Zhen, PhD8.6.2013

2. Overview of HIV life cycle • HIV life cycle: • Binding and Fusion • Entry • Reverse transcription • Integration • Viral RNA and protein expression • Assembly and budding • Maturation • HIV target cells: • CD4T cells, • Macrohpages, • Dendritic cells

3. Anti-retroviral therapy • HAART: Highly active anti-retroviral therapy • Usually combine several drugs that target different stages of HIV replication • Classes: • Entry inhibitors (Maraviroc/enfuvirtide) • Nucleoside reverse transcriptase inhibitors (NRTI) and nucleotide reverse transcriptase inhibitors (NtRTI) (tenofovir, deoxythymidine, zidovudine, etc) • Non-nucleoside reverse transcriptase inhibitors (NNRTI) (nevirapine, etc) • Integrase inhibitors (Raltegravir) • Protease inhibitors (Indinavir, Nelfinaviretc)

4. Overview of HIV life cycle X • HIV life cycle: • Binding and Fusion • Entry • Reverse transcription • Integration • Viral RNA and protein expression • Assembly and budding • Maturation • HIV target cells: • CD4T cells, • Macrohpages, • Dendritic cells X X X

5. Effect of HAART in US

6. Overview of adaptive immunity

7. 4 – 8 weeks HIV disease progression – clinical latency AIDS and Death Acute Asymptomatic (clinical latency) Primary infection HIV viral load CD8+ T cell Neutralizing Antibodies Levels (Separate Scales) CD4+ T cell Years

8. T cell homeostasis

9. Immune reconstitution during HAART • Phase 1: Sudden halt in viral production provokes a rapid increase in CD4 T cells in the first three months • Phase 2: Slow recovery over several years, results mostly from regeneration of naïve CD4 T cells population.

10. Immune reconstitution during HAART • Restoration of pathogen and HIV-specific T lymphocytes

11. Autran et al.:Experimental Protocol 8 HIV-infected, previously untreated individuals with advanced HIV-infection. Protease inhibitor; Ritonavir AZT Dideoxycytosine Measured viral RNA in the plasma Determined lymphocyte counts in the blood Phenotyped the cells Determined responses to recall antigens

12. Phenotype of CD4+ T-cells following drug therapy 300 250 200 150 Cells (per ml) 100 50 0 0 5 10 15 20 25 30 35 40 Naïve CD4+ cells Weeks Memory CD4+ cells Pakker et al. Nature Medicine 1998 Total CD4+ cells

13. Naïve CD8+ cells Memory CD8+ cells Total CD8+ cells Phenotype of CD8+ T-cells following drug therapy 900 800 700 600 500 400 Cells per ml 300 200 100 0 0 5 10 15 20 25 30 35 40 Weeks Pakker et al. Nature Medicine 1998

14. HAART Roederer Nature Medicine 1998 Changes in T-cell subsets with drug therapy CD8+ T-cells Memory Naive CD4+ T-cells Memory Naive Years after infection

15. CD3+8+DR+ Infectious Cells CD45RO+DR+ CD4+DR+ Total CD4+ cells Decrease in HLA-DR expression in T-cells after drug therapy 30 25 20 % Positive Cells 15 10 5 0 0 2 4 6 8 10 12 14 Months Autran et al. Science 1997

16. Restoration of CD4+ T-cell responses to tuberculin 100 10 Stimulation Index 1 0.1 -1 0 1 2 3 4 5 6 7 Months Autran et al. Science 1997

17. HAART effects on immune response • Increase CD4 cell number and function • Increase memory and naïve CD4 and CD8 cells • Decrease markers of cellular activation • Normalize distortion in CD4 repertoire • Reconstitution of antigen-specific CD8 T cell and B cell responses to opportunistic pathogens

18. 1000 100 10 1 Plasma viral load before and after drug treatment Slope: -0.21 t 1/2: 3.3 days RNA copies per ml (x 103) -10 -5 0 5 10 15 20 25 30 35 Days Ho et al. Nature 1995

19. Viral Half-Life • Extrapolating from the curves: • Between 108 and 109 virions are cleared each day suggesting • that viral production is 108 to 109 virions per day • The T ½ is ~2 days (current estimates place it as even shorter) • Unfortunately, not all the virus is cleared

20. Viral Latency • The latent viral pool persists in everyone following Highly Active • Anti-Retroviral Therapy (HAART) • Is established soon after infection • T1/2 of replication competent virus is ~44 months therefore • eradication could take up to 60 years.

21. Evidence of Viral Reservoirs Primary Infection Viral Rebound Viral Setpoint Cessation Of HAART Plasma Viral RNA HAART 50 copies Infection

22. Forms of HIV-1 “Latency” • Compartmentalization • CD4 + cells • Pre-integration complexes – labile vs. stable • Post-integration proviral DNA • Drug resistance: • While drug resistance does occur, there is evidence • of wild-type HIV-1 replication.

23. Modelfor establishment and maintenance of HIV-1 reservoirs Death Activation: antigen Activated T-cell Quiescent T-cell Activated T-cell and renewed viral replication

24. HIV T cell dynamic on and off HAART

25. Factors influencing immune restoration with antiretroviral therapies Blood, 2011

26. Factors influencing immune restoration with antiretroviral therapies Blood, 2011

27. Therapeutic possibilities to improve immune reconstitution

28. Q&A What is HAART? Can virus be cleared by HAART and why? What are the two phase of immune reconstitution after initiation of anti-retroviral therapy?

29. Q&A What is HAART? HAART stands for Highly Active Antiretroviral Therapy. The usual HAART regiment combines three or more different drugs. Can virus be cleared by HAART and why? HAART regiments can reduce the amount of active virus and in some case can lower the number of virus until it is undetectable by current blood testing techniques. However, usual HAART treatment cannot clear HIV infection due to the fact that virus can establish latent infection in the patient. What are the two phase of immune reconstitution after initiation of anti-retroviral therapy? First a rapid initial rise of CD4 T cell counts in the first few months, primarily due to increase in memory T cells, and followed by a slow, steady increase in naïve T cell counts that can continue for years with sustained suppressive ART.

30. Group Discussion: Early treatment Benefit of early treatment: Limit HIV persistent reservoir Limit diversity of the virus Preserves immune responses Cons: Increase rate of multi-drug resistance?