Viral Latency and T-cell Responses After HAART - PowerPoint PPT Presentation

Loading...

PPT – Viral Latency and T-cell Responses After HAART PowerPoint presentation | free to download - id: 6afd86-NWRiM



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Viral Latency and T-cell Responses After HAART

Description:

Viral Latency and T-cell Responses After HAART Experimental Protocol: Ho et al. Nature 1995 Plasma viral load before and after drug treatment Viral Half-Life Viral ... – PowerPoint PPT presentation

Number of Views:0
Avg rating:3.0/5.0
Date added: 23 September 2019
Slides: 44
Provided by: BethDJa
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Viral Latency and T-cell Responses After HAART


1
Viral Latency and T-cell Responses After HAART
2
Experimental Protocol Ho et al. Nature 1995
20 HIV-infected individuals with CD4 T cell
counts ranging from 36 to 490 cells (mm-3)
Protease InhibitorABT-538
Measure viral RNA in the plasma Measure CD4
T-cells in the blood
3
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
4
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

5
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.

6
Evidence of Viral Reservoirs
Primary Infection
Viral Rebound
Viral Setpoint
Cessation Of HAART
Plasma Viral RNA
HAART
50 copies
Infection
7
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.

8
Model for establishment and maintenance of HIV-1
reservoirs
Death
Activation antigen
Activated T-cell
Quiescent T-cell
Activated T-cell and renewed viral replication
9
What Researchers Know So Far
  • Infection of naïve cells occurs infrequently and
    tends
  • to result in more labile forms of virus.
  • Viral DNA is most abundant in CD45RA- T-cells
  • Effector or memory? 1 per 106 cells.
  • Viral RNA is more abundant in activated, HLA-DR,
  • T-cells.
  • Macrophages are also a cellular reservoir for
    HIV-1,
  • but are short lived, therefore their
    contribution
  • to the long-lived reservoir is unclear.

10
Increase in CD4 cell counts after drug treatment
Slope 2.4
Ho et al. Nature 1995
11
Inverse correlation between baseline CD4 cell
count and CD4 cell recovery
0.1
0.09
0.08
0.07
0.06
Exponential slope of CD4 increase
0.05
0.04
0.03
0.02
0.01
0
0
50
100
150
200
250
300
350
400
450
Baseline CD4 cell count
Ho et al. Nature 1995
12
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
13
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
14
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
15
Changes in T-cell subsets with drug therapy
Roederer Nature Medicine 1998
CD8 T-cells
Memory
Naive
CD4 T-cells
Memory
Naive
Years after infection
16
Re-expression of CD25 on CD4 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 a. Science 1997
17
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
18
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
19
Response of CD8CD38 T-cells To HAART
20
Summary
  • With the addition of a protease inhibitor, plasma
    viral load drops but is not completely
    eliminated viral latency
  • As viral load drops CD4 T-cells increase
  • CD8 T-cells increase then decline slightly
  • Activation antigens decrease on both subsets
  • CD4 T-cells re-express CD25 and regain
    proliferative
  • responses to recall antigens
  • The greatest T-cell increases are in the memory
    phenotype cells
  • After about six weeks slow, but steady, increases
    are observed in the naïve T-cell compartment

21
Where Do The T-cells Come From?
  • Homeostasis mechanisms trigger proliferation of
    surviving cells.
  • Redistribution of cells from inflammed tissues,
    back into blood
  • causes an observed increase in cells.
  • Naïve cells Thymus vs. gut vs. proliferation?

22
Can The Thymus of Adults Contribute To T-cell
Reconstitution?
23
Phenotypic markers of T-cell development in the
Thymus
BM
Thymus
PB
CD1 CD3 CD4 CD8- CD69
CD1- CD3 CD4 CD8- CD69
CD1- CD3 CD4 CD8- CD69-
CD34 CD1- CD3- CD4- CD5/- CD8-
CD34/- CD1 CD3- CD4 CD5 CD8-
CD34- CD1 CD3- CD4 CD5 CD8
CD34- CD1 CD3 CD4 CD5 CD8 CD69
CD1 CD3 CD4- CD8 CD69
CD1- CD3 CD4- CD8 CD69
CD1- CD3 CD4- CD8 CD69-
24
(No Transcript)
25
(No Transcript)
26
Summary of Adult Thymus Specimens
Corrective Cardiac Surgery
27
Human Thymocyte Differentiation
CD34
CD5
CD69
CD3
CD62L
28
Adult And Fetal Thymocytes Demonstrate Similar
Subset Distribution
Age
Fetal
CD1a-PE
CD4-TC
23 yrs.
83
2
79
13
52 yrs.
14
6
CD8-FITC
CD5-FITC
29
Adult And Fetal Thymocytes Demonstrate Similar
Subset Distribution
Age
80
Fetal
11
6
CD3-PE
CD69-PE
23 yrs.
14
69
12
22
52 yrs.
14
62
CD8-FITC
CD8-FITC
30
Phenotypic markers of T-cell development in the
Thymus
BM
Thymus
PB
CD1 CD3 CD4 CD8- CD69
CD1- CD3 CD4 CD8- CD69
CD1- CD3 CD4 CD8- CD69-
CD34 CD1- CD3- CD4- CD5/- CD8-
CD34/- CD1 CD3- CD4 CD5 CD8-
CD34- CD1 CD3- CD4 CD5 CD8
CD34- CD1 CD3 CD4 CD5 CD8 CD69
CD1 CD3 CD4- CD8 CD69
CD1- CD3 CD4- CD8 CD69
CD1- CD3 CD4- CD8 CD69-
31
Co-stimulation of Adult Thymocytes
Unstimulated
Stimulated
Medium
Medium
Anti-CD28
Anti-CD3
3 Days
3 Days
Harvest
Stain for activation markers
32
Adult Thymocytes Respond To Co-stimulatory Signals
33
Adult
Fetal
CD8
Adult Thymocytes Display A Diverse Vb
Repertoire
CD4
CD4CD8
Vb13.6
Vb13.2
Vb20
Vb21.3
Vb13.1
Vb18
Vb5.1
Vb12
Vb6.7
Vb11
Vb17
Vb23
Vb14
Vb16
Vb22
Vb1
Vb2
Vb3
Vb5
Vb8
Vb9
34
Can Adult Thymocytes Migrate To The Periphery?
35
Signal joint (sj) and coding joint (cj) TREC
production from the a/d locus
a locus
d locus
a locus
Va
Vd
dRec
Dd
Jd
Cd
yJa
Ja
Ca
sj PCR
cj PCR
Adapted from Martie C. M. Verschuren, Thesis
36
TREC
-T-cell receptor Rearrangement Excision
Circles - are detected in phenotypically naive
T-cells, but not in memory T-cells or in
B-cells. - decline in the peripheral blood with
age, after thymectomy, and in HIV-infected
individuals. - increase in HIV-infected
individuals undergoing HAART.
Douek et al. Nature 1998
37
TREC Positive Cells In The Periphery of Adults
100000
10000
Sj TRECs per mg of DNA
1000
100
0
10
20
30
40
50
60
70
80
Age (years)
38
TREC changes during HAART
6
1
0
C
-
2
5
A
-
3
6
B
-
2
8
1
4
-
1
2
5
1
0
1
0

8
4
1
0
6
4
3
1
0
2
2
1
0
5
0
1
0
0
1
5
0
2
0
0
2
5
0
0
5
0
1
0
0
1
5
0
2
0
0
2
5
0
0
5
0
1
0
0
1
5
0
2
0
0
25
0
0
6
1
0
8
D
-
2
9
F
-
3
6
E
-
2
9
7

5
6
1
0
5
4
4
1
0
-
3
3
2
1
0
1
2
1
0
5
0
1
0
0
1
5
0
2
0
0
2
5
0
0
5
0
1
0
0
1
5
0
2
0
0
2
5
0
0
5
0
1
0
0
1
5
0
2
0
0
2
5
0
0
6
1
0
8
G
-
2
7
H
-
3
2
I
-
2
2
7
5
1
0
6
5
4
1
0
4
3
3
1
0
2
1
2
1
0
5
0
1
0
0
1
5
0
2
0
0
2
5
0
0
5
0
1
0
0
1
5
0
2
0
0
2
5
0
0
5
0
1
0
0
1
5
0
2
0
0
2
5
0
0
6
1
0
8
J
-
6
3
7
Sj TREC x103 per mg naïve CD4 cell DNA
5
1
0
6
5
4
Naïve CD4 T cells x102 per ml blood
4
1
0
3
3
2
1
0
HIV RNA copies per ml of plasma
1
2
1
0
5
0
1
0
0
1
5
0
2
0
0
2
5
0
0
Douek et al. Nature 98
39
Conclusions
1. Thymopoiesis is ongoing in adults, resulting
in functional T-cells with a diverse TCR-Vb
repertoire.
2. CD4, phenotypically naïve, TREC positive
T-cells increase following HAART suggesting that
the adult thymus contributes to T-cell
reconstitution.
3. The thymic microenvironment remains
functional after exposure to HIV.
Douek et al. 1998 Nature 396 690 Withers-Ward et
al. 1997 Nature Med. 3 1102 Jamieson et al.
1999 Immunity, 10 569
40
Conclusions cont.
Taken together, these results suggest that
therapeutic strategies to enhance thymopoiesis in
the adult may increase T-cell reconstitution in
HIV-infected individuals treated with HAART, or
in cancer patients undergoing chemotherapy. In
addition, these strategies may improve T-cell
responses in the elderly.
41
Strategies to Improve T-cell reconstitution
42
Vishwa Deep Dixit Current Opinion in
ImmunologyVolume 22, Issue 4, August 2010
521-528
43
Therapeutic Strategies
  1. IL-7 Modulates thymic output, expands and
    supports survival of naïve and memory T-cells.
    In HIV-1 infected individuals see increases in
    functional T-cells(1).
  2. IL-15 Supports survival of NK, NKT and CD8
    memory T-cells(2)
  3. Growth Hormone acts as a pro-thymopoietic agent
    (3)
  4. Ghrelin Reduces pro-inflammatory cytokines and
    reverses thymic involution (3)
  5. Leptin Increases peripheral IGF1, results in
    thymic regeneration (3)
  6. IGF1 expands progenitors in bone marrow,
    increases thymic epithelial niches (3)
  7. CR mimetics Maintains TCR diversity and
    increases thymopoiesis (3)

  1. Levy et al. Journal of Clinical Investigation
    2009, 119997
  2. Van den Brink et al. Nature 2004, 4856
  3. Vishwa Deep Dixit, Current Opinion in Immunology,
    2010 521
About PowerShow.com