Progression Markers in HIV infection '.

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Progression Markers in HIV infection '.
Savita Pahwa, MD Professor Microbiology
Immunology Pediatrics Medicine Director, Miami
CFAR University of Miami Miller School of
Medicine

• São Paulo, Nov 16, 2011

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Natural course of HIV infection
Acute Phase
Chronic Phase
Burst of viremia-higher peak in infants than in
adults and prolonged set point also higher in
infants. Latent reservoir established
Eclipse phase- approx 10 d initial period of
spread from site of infection to lymphoid tissue
and gut, seeds reservoirs Window of opportunity
Qualitative and Quantitative loss of CD4 T cells
CD4 counts
Ongoing virus-host interaction and ARV have many
indirect effects which lead to immunologic
defects and metabolic complications
Most defects in immunity in acute phase are
directly inflicted by HIV Early cART preserves
immunity
Plasma HIV RNA copies/ml
Eclipse Phase
CD4 gt25
CD4 15-24
CD4 lt15
Limit of detection of plasma HIV
Latent HIV Reservoir
years
100d
Entry
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Acute HIV infection

• Gastrointestinal tract is the most prominent
  early site of virus replication (1-3 weeks post
  infection)
• Rapid and extensive depletion of CCR5 CD4 T
  cells in the gut occurs within days of primary
  HIV infection. TH-17 subset is wiped out. Gut
  pathology is an important driver of HIV disease
  pathogenesis
• Information is limited for infants

Acute Phase
Chronic Phase
Loss of CD4 T cells in the gut
loss of CD4 T cells in peripheral blood
Plasma HIV RNA copies/ml
CD4 counts
CD4 gt25
CD4 15-24
CD4 lt15
Limit of detection of plasma HIV
Latent HIV Reservoir
Time
years
weeks
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Biomarkers of HIV disease progression

• CD4
• Virus load

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Estimated Probability of AIDS within 12 Months by
Age and CD4 Percentage in HIV-Infected Children
Receiving No Therapy or Zidovudine Monotherapy
(HIV Pediatric Prognostic Markers Collaborative
Study)
Meta-analysis 17 studies 3,941 HIV-infected
children
Infants HIV disease progression risk exists even
at high CD4 counts
The risk of disease progression associated with a
specific CD4 percentage or count varies with
age of the child. All age groups demonstrate
rapid increases in risk as CD4 percentage
decreases below 15-20.
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Beyond CD4- seeking immunologic biomarkers of
disease progression in chronic HIV infection 1.
Impaired Innate and Adaptive T Cell Immunity
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Principle Components of Innate and Adaptive
Immunity
DC
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Host Virus Interaction Components of Antiviral
Immunity
ADAPTIVE IMMUNITY
INNATE IMMUNITY
DC
CTL
HIV virion
NK
CD8
Frontline FIRST LINE OF ATTACK
Infected CD4 T cell
CD4
Y Y Y
Helper T Cells
Uninfected CD4 T cell
Neutralizing antibodies
B cell
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CD8 T cells and Cellular Immune Response Against
HIV
Death of HIV-infected target cells
Helper T cell
APC
CD4
TCR
CTL
CD8
CD8
CD8
CD8
CD8
MHC Class I
TCR
Effector
CM
TMEM
Naive
Perforin, Granzyme, Fas L Cytokines IFN?,
TNF? Chemokines MIP1?/?,

/- -- -- --
--
-- -- --
CD27 CD45RA CD62L CCR7

Proliferation
--
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T Cell Intracellular Cytokines
Signature of a protective immune response
Polyfunctional T cells Loss of polyfunctionality
poor immune response
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HIV impairs polyfunctional CD4 T Cell responses
against BCG in BCG vaccinated HIV infected infants
Qualitative differences in BCGspecific CD4 T
cell responses in the infant groups, based on
coexpression of type I cytokines
Mansoor et al. JID 2009199
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Main CD4 T cell subsets
?
?
King C, et al. Annu. Rev. Immunol. 2008
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Summary of immune defects in chronic HIV
infection in children
Innate immunity DC defects in pDC
function and CCR7 expression IFN-a
controversial NK cells impaired killing T
cells Phenotype imbalance of maturation
subsets, Proliferation reduced Polyfunctional
CD4 and CD8 T cells reduced, specially IL-2
secreting cells CD8 CTL effector
molecules perforin is decreased
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Markers of disease progression II. Immune
Activation and Immune Exhaustion
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Cellular immune activation in chronic HIV
recognized early in the epidemic
CD45 RA CD45 RO
CD 28 CD95 (Fas) HLA-DR CD38 CD57
changes seen in both, CD4 and CD8 subsets
Activation Markers Expansion of CD8 DR CD38
T cells Loss of CD45RA naive T
cells
predominantly in CD8 T cells
Expansion of CD8 DR CD38 T cells is a better
predictor of disease progression than loss of CD4
T cells than increase in virus load
6/6/1995
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Causes of immune activation

• Overt or hidden virus replication
• Activation by HIV and its gene products
• Co-infections, e.g. Tuberculosis
• Microbial translocation in the gut

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Normal
Pathological
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MT correlates with T cell (HLADR/CD38) and
monocyte (sCD14) activation
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HIV infected children have increased microbial
translocation
Plasma LPS and 16S rDNA are elevated
LPS positively correlates with 16S rDNA
Chennai Cohort
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MT is correlated with VL, activated T cells
monocytes and inversely correlated with CD4
VL
Activated T cell
Activated monocytes
CD4

Baseline LPS
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Immune Exhaustion
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Co-stimulatory molecules on T cells and APC
T cell activation
MHC-II/ peptide
TcR
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PD-1 is a negative regulator of
CTL-Engagement Turns CTL OFF
Off
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T cell exhaustion in HIV

• Exhausted T cells are characterized by distinct
  phenotype and negative regulatory pathways
• Cell surface inhibitory receptors PD-1, LAG-3,
  CD244, CD160, Tim-3, CTLA-4, others
• CD122lo CD127lo phenotype
• Soluble factors (IL-10)
• Conditions favoring immune exhaustion of HIV-sp T
  cells
• High virus load
• Poor CD4 Help
• Poor APC function
• Inflammation
• Lymphoid architecture disruption

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PD-1 expression is correlated with T Cell
exhaustion during chronic viral infections.
Freeman et al JEM 203 2223, 2006
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Generation of Effector T cells, Memory T cells,
Exhausted Effector Cells Role of PD-1 and its
Ligands
Freeman et al JEM 203 2223, 2006
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Markers of disease progression III. B cell
Defects and Impaired Vaccine Responses
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HIV induced alterations of human B cell
subpopulations
Moir et al, Nat rev Immunol 2009
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H1N1/09 influenza Ab responses of HIV infected
persons
ART treated, aviremic, HIV patients n17
Healthy controls (HC), n8
one i/m dose of 15µg inactivated, monovalent
H1N1/09 vaccine
Responders, All
Responders, n9 Non responders, n8
Evaluate B cell phenotype and function Peripheral
TFH cells T0, T1 (d7), T2 (wk4), T3 (wk 24)
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B cell subset characterization by flow cytometry
Isotype
Plasmablasts (SPB)
Isotype
SPB
IgG1-Alexa-700
100
Pallikkuth et al JI 2011
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Memory B cell expansion occurs at 4 wks in
vaccine responders
B cell subsets before and after vaccination
(A)
T0 T2 T0 T2
T0 T2 HC
Vac. responder Vac. non-resp
(C)
Elispot for H1N1 flu sp Memory B cells
Resting Memory B cells
HC R NR
HC R NR
Pallikkuth et al JI JACI, 2011
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T Follicular Helper Cells (TFH)
The GC reaction is facilitated by the interaction
between surface molecules on TFH cells and
developing B cells, both of which use CXCR5 to
localize there.

• TFH
• CD4 T cells
• Memory
• CXCR5
• ICOS
• PD1
• Bcl6
• CCR7lo, CD127lo
• Main IL-21 producers

Spolski R , Leonard W J Int. Immunol. 2009227-12
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TFH cell expansion occurs in H1N1/09 vaccine
responders and correlates with memory B cells and
H1N1 Ab titer
A
B
C
D
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Summary Failed H1N1/09 Vaccine Responses

• Poor plasmablast expansion on d7
• Poor memory B cell expansion at wk 4
• No increase in IL-21R on B cells
• No increase in plasma IL-21
• Poor Ag-stimulated IL-21 production
• Poor expansion of peripheral TFH cells

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Early HAART protects integrity of memory B cells
and longevity of humoral responses in HIV-1
vertically-infected children
Pensieroso S et al Proc Natl Acad Sci U S A. 2009
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IV. Other Biomarkers related to disease
progression

• Host factors and host genetics

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Virus Host Interaction

• HIV usurps host cell proteins at various points
  in its replication cycle
• 237 novel genes for HIV Host dependency factors
  (HDF) identified (Brass, Science, 08)
• HIV is armed with machinery to overcome innate
  protective factors of the host, eg Apobec 3G
• Immune response is crippled by deleterious
  effects of virus on the host cells through a
  variety of different mechanisms.

Protective Immune response
Ineffective Immune response or Deleterious
Immune Response Increased virulence/replication
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Assessing Utility of Biomarkers in HIV/AIDS

• Biomarkers can provide insight for
• Clinical progression infectious and
  non-infectious complications
• Response to vaccination
• Response to drugs
• Response to infectious pathogens

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Elite Controllers, LTNP and Chronic Progressors
Long term non-progressors
Elite Controllers
EC
lt 1
5

• Maintain durable HIV control to lt50 copies/mL
  without HAART
• Rarely progress
• Also known as HIV controllers
• Low virus reservoirs

• Definition based on CD4 control for 7-10 years
  without HAART
• VL usually lt2,000 HIV RNA copies/ml
• Most ultimately show CD4 decline better survival
  if stable for gt10 years

gt90

• Inability to control virus without HAART
• With early HAART many progressors achieve
  characteristics of EC but virus rebounds if HAART
  is discontinued

Deeks SG and Walker BD Immunity 271286, 2007
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Virus Reservoirs

• The stable elite controllers HIV reservoir is
  extremely low
• Early therapy and long term viral suppression can
  limit the reservoirs, similar to that of stable
  Elite controllers
• The HIV reservoir is strongly linked to the
  hosts MHC alleles and CD8-specific T cells
• The HIV reservoir poses the greatest challenge
  for achieving a cure

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Research
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An example of functional cure the Berlin patient
Timothy Brown

• In 2007, a patient was given a stem cell
  transplant with the CCR5D32/D32 mutation for
  treatment of relapse of AML
• 3 years after transplant, CD4 T-cell numbers have
  returned to the normal range of healthy patients
  whereas HIV RNA and DNA remain continuously
  undetectable in plasma and PBMC

The molecule CCR5 is a co-receptor necessary for
HIV to enter the CD4 T cells
Geographic distribution of the CCR5-?32 allele
(Faure et al, Virology Journal, 2008 )
CD4-CCR5-HIV interaction (Atreya et al, THURJ,
2009)
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How can we prevent progression of HIV disease?

• Early treatment seems to be the best in limiting
  reservoirs and early disease outcome but it
  subjects patients to life-long therapy
• Strategies to discontinue or de-intensify after
  initial therapy are under investigation. Does
  this approach re-seed reservoirs?
• Potent cART is desired but we need to understand
  if drugs that control virus are also as good for
  immune reconstitution
• Our goal is to achieve a cure and restoration of
  health for all HIV infected-ie reversal of late
  complications

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Summary of immune defects in chronic HIV
infection in children
Most appear to have an intact immune system at
birth similar to healthy newborns (good thymus,
high T regs) Innate immunity DC Defects in
pDC function and CCR7 expression IFN-a
controversial NK cells impaired killing T
cells Phenotype imbalance of maturation
subsets, increased PD-1 Proliferation
reduced Polyfunctional T cells reduced, sp IL-2
secreting cells CTL effector molecules perforin
is decreased Increase in apoptosis, immune
activation markers and exhaustion B
cells Polyclonal hypergammaglobulinemia,
decreased antibody responses to childhood
vaccinations, exhaustion
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Thank you