Avances en investigación básicaAvances en investigación básicaJavier Martinez-Picado

19th Conference on Retroviruses and Opportunistic Infections

Seattle, March 5-8, 2012

Javier Martinez-Picado19th Conference on Retroviruses and Opportunistic Infections

Seattle, March 5-8, 2012

Barcelona, 13/03/12

Restrictions FactorsTowards a HIV-1 Cure

Highligthed Topics Highligthed Topics

Restriction factors: a defense against retroviral infection

SAMHD1 is a myeloid-cell-specific HIV-1 restriction factor counteracted by Vpx

Restriction factors: a defense against retroviral infection

SAMHD1 is a myeloid-cell-specific HIV-1 restriction factor counteracted by Vpx

Barcelona, 13/03/12

Restriction Factors Restriction Factors

Benkirane #63Lieberman #64

Luban #65Kewal Ramani #66

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Host defenses against retroviruses

Host defenses against retroviruses

Modified from Kirchhoff, 2010 Host Cell Microb

Laguette & Benkirane, 2012. Trends in Immunology

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Dendritic Cells Dendritic Cells

DCs coordinate immune responses to invading pathogens

DCs can carry HIV-1 to target CD4+ T cells, amplifying the cytopathic effects of the virus

SAMHD1 is responsible for blocking replication of HIV within dendritic cells, although it functions in other myeloid cells as well

SAMHD1 can be antagonized by vpx

Benkirane #63

Barcelona, 13/03/12

What does make DC refractory to HIV-1 ?

What does make DC refractory to HIV-1 ?

Modified from emulenews

Proteosomal Degradation

REVERSETRANSCRIPTION

RESTRICTIVE INFECTION PERMISSIVE INFECTION

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What does make DC refractory to HIV-1 ?

What does make DC refractory to HIV-1 ? Vpx addition or Silencing of SAMHD1 increases the

susceptibility of monocytic-derived DCs to infection

Laguette et al. Nature 2011

MDDC

siRNAVLP-Vpx

THP-1

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SAMHD1SAMHD1 SAM domain and HD domain form a dimer that in humans is encoded by the SAMHD1 gene.

Chr 20sterile alpha motif

It belongs to a family of proteins that have been involved in a rare genetic disorder, the Aicardi-Goutières Syndrome, an inflammatory encephalopathy that resembles congenital viral infection, such as vertically acquired HIV.

Laguette & Benkirane, 2012. Trends in Immunology

Barcelona, 13/03/12

SAMHD1 cuts the power for HIV-1SAMHD1 cuts the power for HIV-1

SAMHD1 is a potent dGTP-stimulated triphosphohydrolase that restricts the availability of dNTPs, the building blocks of genetic material, in macrophages and dendritic cells.

dNTP → dN + Pi The molecule cuts off the supply line of dNTP available for cDNA synthesis by RT and so prevents viral replication

SAMHD1 is the only HIV-1 restriction factor against which the virus has not evolved a neutralizing strategy. Its discovery opens new possibilities to understand the intricacies of the relation between lentiviral evolution and primate hosts.

Lahouassa et 1l 2012 Nat ImmunolJermi 2012 Nat Rev Microbiol

Laguette et al. 2012 Hist Cell Microb

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SAMHD1 is a restriction factor that blocks HIV-1 replication in myeloid cells.

SAMHD1 is antagonized by vpx, a molecule present in HIV-2 and SIV but not in HIV-1.

Modulating SAMHD1 function could render human hosts more prone to develop appropriate innate and adaptive immune responses.

Therapies that mimic the effect of SAMHD1 or otherwise deplete the intracellular supply of dNTPs could represent a new approach to HIV treatment and cure.

Potential role in the development of dendritic-cell-targeted vaccines against HIV/AIDS.

ImplicationsImplications

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If HIV-1 does not have vpx but HIV-2 does, why HIV-1 is more pathogenic than HIV-2?

ParadoxParadox

vpx

HIV Reservoirs and Cure Research

HIV Reservoirs and Cure Research

Pathways toward a Cure: Viral Latency and Reservoirs

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HIV Cure HIV Cure

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HAART is effectiveHAART is effective

Suppression to below detectable HIV-1 RNA levels is rapid and durable.

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However, despite prolonged HAART …

However, despite prolonged HAART …

Replication competent viruses can be rescued ex vivo from resting CD4+ T cells

Low level plasma viremia (< 50 copies) persists Immune activation diminishes but does not normalize Plasma viremia rebounds after treatment interruption

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What sustains HIV-1 despite HAART?

What sustains HIV-1 despite HAART?

Ongoing HIV-1 replication cycles in cells located in sanctuary sites where drug levels are suboptimal

Latently infected cells (resting central memory T cells): Might produce virus upon reactivation.

Might proliferate

Lewin #106

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New markersNew markers

Plasma: HIV RNA Ultrasensitive HIV RNA

Cell-associated: Total HIV DNA Integrated cell HIV DNA Episomal HIV DNA HIV RNA

Cell-activation markers

Inflammation

Lewin #106

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Viral replication in pharmacologic sanctuaries

Viral replication in pharmacologic sanctuaries

Quantitation of intracellular ARV concentrations, including NRTI-triphosphates in PMBC, LN and GALT.

Pharmacokinetic data suggest drug-specific compartmentalization

Fletcher #108

104

103

102

101

1

ATV

(ng/

mL)

PBMC LN Ileal Rectal

EFV

(ng/

mL)

105

103

102

101

1

104

PBMC LN Ileal Rectal

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Viral replication in pharmacologic sanctuaries

Viral replication in pharmacologic sanctuaries

Hypothesis: inadequate drug penetration may contribute to cryptic replication of HIV, which sustains HIV infection.

Mechanisms: Physiochemical characteristics Susceptibility for and distribution of influx and efflux

transporters (Minuesa #590; P-gp in primary CD4+ T cells and raltegravir intracellular concentrations)

Drug metabolizing enzymes Expression of phosphorylating enzymes Activation state of the compartment Host genetic traits.

Fletcher #108

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Reservoirs,does time of treatment initiation

matter?

Reservoirs,does time of treatment initiation

matter? Treatment of early HIV infection reduces viral reservoir to levels found in elite controllers

Buzon et al. #151

Tota

l HIV

-1 D

NA

Chronic

Acute

Elite C Acute Chronic

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New chemotherapy against latencyNew chemotherapy against latency Transcriptional activators: reactivation of the latent HIV-1

without inducing T cell activation

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Chromatin Reconfiguration for Purging HIV-1 from the Latent Reservoir

Chromatin Reconfiguration for Purging HIV-1 from the Latent Reservoir

Johnstone, Nat Rev Drug Discov, 2002

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Vorinostat Disrupts HIV-1 Latency in Patients on ART

Vorinostat Disrupts HIV-1 Latency in Patients on ART

 n=5; CD4 count 562 cells/µL; 4 years of ART; 400 mg single dose of voronistat; no AE

👍 PBMC cellular histone acetylation

👍HIV RNA levels increased significantly (5-fold) in pools of resting CD4+ cells obtained after SAHA dosing compared to BL

Proof-of-concept for HDAC inhibitors as a therapeutic class to directly attack and potentially eradicate latent HIV infection

No demonstration of viral production

Similar study suggested in NHP without data (Lifson #107)

Archin #157LB

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Autologous ZFN CCR5-disrupted CD4+ T cells

Autologous ZFN CCR5-disrupted CD4+ T cells

June #155

Barcelona, 13/03/12

Autologous ZFN CCR5-disrupted CD4+ T cells

Autologous ZFN CCR5-disrupted CD4+ T cells

 SB-728-T infusion increases CD4 counts that persist over time.

SB-728-T expands rapidly and home to the gut.

3/6 subjects with >11 months follow up had an ~1-log decrease in total HIV-1 DNA over time: SB-728-T may decrease proviral DNA.

In one subject with the highest level of CCR5 modification, pVL was controlled (< limit of detection) without HAART.

These data suggest that in addition to the previously documented increases in CD4 cell, SB-728-T may also suppress HIV replication

June #155

Barcelona, 13/03/12

SummarySummary