Dale and Betty Bumpers
Vaccine Research CenterNational Institute of Allergy and Infectious DiseasesNational Institutes of Health
Richard A. KoupVaccine Research Center
Lymph node structure and HIV-1 infection:
T cell immunopathogenesis
Background
• HIV replication is active in lymph nodes throughout the course of HIV infection
• HIV leads to an initial hypertrophy, followed by involution of lymphoid tissues (Tim Schacker)
• SIV infection in rhesus macaques has a similar pathogenesis to HIV infection in humans (Guido Silvestri) and can be used to study the immuno-pathogenesis of HIV infection in lymph nodes
• In this talk I will concentrate on using acute and early SIV infection of rhesus macaques to model HIV pathogenesis in lymph nodes
Janeway’s Immunobiology (8th Edition)
The Lymph Node has a Complicated Structure
Simplified LN Structure
Paracortical Area(T cells)
Lymphoid Follicle(B cells)
Germinal Center(B and T cells)
Light Zone(T/B cell interaction)
Dark Zone(B cell proliferation)
Simplified LN Structure – HIV Infection
Uninfected Infected - Early
Germinal Center Hypertrophy
(increased germinal center T cells)
Loss of non-germinal
center T cells
Infected - Late
Outline
• Virus replication in LN during acute/early HIV/SIV infection
• Changes in CD4 T cell populations in LNs during acute/early HIV/SIV replication
• Underlying mechanisms• Non-T cell consequences
SIV as a model for HIV infection
Nature 434:1093-7, 2005
Pla
sma
Vira
l Loa
d (L
og10
)
Acute Infection: Plasma Viral Loads
CD
4 T
Cel
ls, %
of C
D3+
Total CD4 Cell Dynamics
0
20
40 InguinalLN
0
20
40
60Jejunum
0
20
40 MesentericLN
0
20
40 PBMC
0 3 7 10 14 17 0 3 7 10 14 17
Days Post-infection
CD
4 M
emor
y, %
of C
D3+
Memory CD4 T Cell Dynamics
Early expansion at d. 3
Loss of ~80% of cells by d. 17
Cell-Associated Viral Loads
0
1x105
2x105
0
1x105
2x105
0
1x105
2x105
0
1x105
2x105
Naive CD4 T Cells Memory CD4 T Cells
PBMC
Inguinal LN
Mesenteric LN
Jejunum
Days Post-infection3 7 10 14 17 3 7 10 14 17
Cel
l-Ass
ocia
ted
Vira
l Loa
d (g
ag C
opie
s / 1
05 cel
ls)
These data do not take into account structural localization within the LN
• Where is the virus replicating with respect to the paracortical T cell zone and the light zone of the germinal center?
• What is happening to CD4 T cell frequency in these areas during acute and early SIV infection?
Paracortical T cell zone
Light zone of the germinal center
Surface markers can distinguish CD4 T cells from these different areas
Paracortical T cell zone
Light zone of the germinal center
CD95
CD
28
CD8
CD
4
CD3
Aqu
a
FSC-A
FSC
-H
PD-1
CC
R7
0 103 10 4 105
0
10 2
10 3
10 4
10 5
70.8
19.5
Where does SIV replicate?
PD-1
CC
R7
0
0.5
1.0
1.5
Early SIV (>2 months)
0
1
2
3
4
5
Acute SIV (3-21 days)
SIV
Gag
DN
A (c
opie
s/ce
ll)
SIV
Gag
DN
A (c
opie
s/ce
ll)p=0.0078p=0.0156
0 103 104 1050
102
103
104
105
ICO
S
CD150
Paracortical T cell zone
Light zone of the germinal center
Would expect to see depletion of CD4 T cells in
germinal centers
SIV: Relative accumulation of CD4 T cells in GCs
0 102
103
104
105
0
102
103
104
105
29.1
12.9
47.8
PD-1
CC
R7
CCR7high
PD-1lowCCR7high/low
PD-1dimTFH
% o
f CM
CD
4 T
cells
SIV acute SIV earlySIV-
CD4 PD1 Ki-67
Michael Gerner, Ron Germain
Light zone:T - B cell interaction
Dark zone:B cell proliferation
Accumulation of GC CD4 T cells during SIV infection: Abundant GCs with retained architecture
Mechanism?
Uninfected Infected - Early
?
No correlation between VLs and percent GC T cells during SIV infection
Percent GC T cells in LN
Vira
l Loa
ds
GC T cells
% o
f CM
CD
4 T
cells
Accumulation of GC T cells is associated with general immune activation (sCD14)
p=0.0013p=0.0004
p=0.0164
sCD
14 (x
106 p
g/m
l)
SIV acute SIV early (high % of TFH)SIV- SIV early (low % of TFH)
SIV: Relative accumulation of GC T cells
IL-6 signaling drives the up-regulation of Bcl-6 and enhanced T cell responses that are seen
during chronic LCMV infection in mice.
Does IL-6 production drive the accumulation of GC T cells during early SIV infection in monkeys?
SIV- SIV+ (early)
p=0.0215
Increase in the IL-6/IL-6R axis is associated with GC T cell accumulation during SIV infection
Plas
ma
IL-6
(pg/
ml) p=0.0136
Percent GC T cells in LN
IL6R
a on
GC
T c
ells
(MFI
)
Mechanism?
Uninfected Infected - Early
IL-62)Altered phospho STAT (3>1)3)
GC T cell differentiation4)
Immune activation1)
Petrovas et al, J. Clin. Invest., 2012
SIV -SIV chronic (low % GC T cells)SIV chronic (high % GC T cells)
p=0.015
0 10 2 10 3 10 4 10 5
010 2
10 3
10 4
10 5
86.1
0 10 3 10 4 10 5
010 2
10 3
10 4
10 5
28.7
0 10 3 10 4 10 5
0
10 3
10 4
10 5
9.84
6.4922.3
61.3
0 10 3 10 4 10 5
0
10 3
10 4
10 5
15.8
0.721.87
81.5
Aqu
a
SSC CD20
CD
3
PNA
IgG
PBMC
LN
LN
PNAhighIgGlow
PNAhighIgGhigh
SIV- SIV+
low TSIV+
high T
GC T cells are TFH that influence B cells differentiation and antibody production
SIV chronic (low % GC T cells)
SIV chronic (high % GC T cells)
gp120
p=0.051
SIV-
spec
ific
IgG
(ti
ter,
x104 )
0
2.5
5
7.5
10
Conclusions• HIV/SIV replication is profound during acute infection• This leads to a massive depletion of memory CD4 T cells
in the LN and gut• CD4 T cell depletion from the gut leads to microbial
translocation and general immune activation (discussed elsewhere)
• Immune activation promotes differentiation of T cells in the LN which move to and accumulate in the GCs (lymphoid hypertrophy)– Non-pathogenic SIV controls immune activation
• Continued immune activation ultimately leads to fibrosis of the lymph nodes
Simplified LN Structure – HIV Infection
Uninfected Infected - Early
Germinal Center Hypertrophy
(increased germinal center T cells)
Loss of non-germinal
center T cells
Infected - Late
Directinfection:
CD4 depletion
Immune activation:
GC hypertrophy followed by
fibrosis
Dale and Betty Bumpers
Vaccine Research CenterNational Institute of Allergy and Infectious DiseasesNational Institutes of Health
Costas PetrovasTakuya YamamotoKristin BoswellJoseph CasazzaRob ParisDavid Ambrozak
Immunology Laboratory NIAID/NCI CollaboratorsMichael GernerRon Germain
Human Immunology Section
Netanya SandlerDaniel Douek
ImmunoTechnology SectionMario Roederer
Lab Animal Medicine
John-Paul ToddSrinivas Rao
