medical immunology immunobiology of hiv infection jan 10, 2013 medical immunology immunobiology of...
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Medical ImmunologyImmunobiology of HIV infection
Jan 10, 2013
Medical ImmunologyImmunobiology of HIV infection
Jan 10, 2013
Keith Fowke539 BMSB789-3818
Medical Immunology IMed 7190
• Topic: HIV resistance• Lecturer: Keith Fowke
• Objectives:– To discuss why HIV induces immune suppression – To discuss why some individuals are resistant to
infection• Expectations:
– To list two main hypotheses why HIV infection leads to AIDS
– To discuss the immunological and non-immunological methods of resistance to HIV infection
Outline
Epidemiology of the disease
HIV Disease HIV replication Why does HIV cause immunodeficiency? What does the CD4+ T cell do?
Three types of T-helper cell. How does HIV decrease CD4+ levels? Apoptosis in HIV infection HIV Resistance
Mechanisms of Resistance
Total: 34.0 million [31.6 million – 35.2 million]
Western & Central Europe
840 000[770 000 – 930 000]
Middle East & North Africa470 000
[350 000 – 570 000]
Sub-Saharan Africa22.9 million
[21.6 million – 24.1 million]
Eastern Europe & Central Asia1.5 million
[1.3 million – 1.7 million]
South & South-East Asia4.0 million
[3.6 million – 4.5 million]
Oceania54 000
[48 000 – 62 000]
North America1.3 million
[1.0 million – 1.9 million]
Latin America1.5 million
[1.2 million – 1.7 million]
East Asia790 000
[580 000 – 1.1 million]Caribbean200 000
[170 000 – 220 000]
Adults and children estimated to be living with HIV 2010
UNAIDS 2011
Estimated number of adults and childrennewly infected with HIV 2010
Western & Central Europe
30 00030 000[22 000 – 39 000]
Middle East & North Africa59 00059 000
[40 000 – 73 000]
Sub-Saharan Africa1.9 million1.9 million
[1.7 million – 2.1 million]
Eastern Europe & Central Asia
160 000 160 000 [110 000 – 200 000]
South & South-East Asia270 000270 000
[230 000 – 340 000]
Oceania33003300
[2400 – 4200]
North America58 000
[24 000 – 130 000]
Latin America100 000100 000
[73 000 – 140 000]
East Asia88 00088 000
[48 000 – 160 000]
Caribbean12 000
[9400 – 17 000]
Total: 2.7 million [2.4 million – 2.9 million]
UNAIDS 2011
~7,400 people HIV infected daily
~300 infected during this talk
Estimated adult and child deaths from AIDS 2010
Western & Central Europe
9900[8900 – 11 000]
Middle East & North Africa35 000
[25 000 – 42 000]
Sub-Saharan Africa1.2 million
[1.1 million – 1.4 million]
Eastern Europe & Central Asia
90 000 [74 000 – 110 000]
South & South-East Asia250 000
[210 000 – 280 000]
Oceania1600
[1200 – 2000]
North America20 000
[16 000 – 27 000]
Latin America67 000
[45 000 – 92 000]
East Asia56 000
[40 000 – 76 000]Caribbean
9000[6900 – 12 000]
Total: 1.8 million [1.6 million – 1.9 million]
UNAIDS 2011
~4,900 people die daily~200 die during this talk
Life Expectancy and HIV
2008: 65,000 people living with HIV in Canada
PHAC: Estimates of HIV Prevalence and Incidence in Canada, 2008
Annual Number of Individuals Testing HIV Antibody Positive 1985-2008 in Manitoba
Manitoba Health & Healthy Living Statistical Update on HIV/AIDS January 1985 –December 2007 (http://www.gov.mb.ca/health/publichealth/cdc/surveillance/dec2007.pdf)
0
20
40
60
80
100
120
140
200020012002200320042005200620072008
Annual Number of Individuals Testing HIV+ in Manitoba
HIV+
In 2011 there are more than 1100 people in HIV Care in Manitoba
HIV in Manitoba 95 New Cases in 2011
Source: Manitoba HIV Program 2012 Report
Outline
Epidemiology of the disease
HIV Disease HIV replication Why does HIV cause immunodeficiency? What does the CD4+ T cell do?
Three types of T-helper cell. How does HIV decrease CD4+ levels? Apoptosis in HIV infection HIV Resistance
Mechanisms of Resistance
A diagnosis of AIDS is made whenever a person is HIV positive and: he or she has a CD4+ cell count <200 cells/µL, or
his or her CD4+ cells account for <14% of all lymphocytes, or that person has been diagnosed with one or more of the AIDS-defining illnesses listed below.
AIDS-defining illnesses: Candidiasis of bronchi, trachea, or lungs
Candidiasis, esophageal Cervical cancer, invasive*
Coccidioidomycosis, disseminated Cryptococcosis, extrapulmonary
Cryptosporidiosis, chronic intestinal (>1-month duration) Cytomegalovirus disease (other than liver, spleen, or lymph nodes)
Cytomegalovirus retinitis (with loss of vision) Encephalopathy, HIV related# (see Dementia)
Herpes simplex: chronic ulcer(s) (>1-month duration) or bronchitis, pneumonitis, or esophagitis Histoplasmosis, disseminated
Isosporiasis, chronic intestinal (>1-month duration) Kaposi sarcoma
Lymphoma, Burkitt Lymphoma, immunoblastic
Lymphoma, primary, of brain (primary central nervous system lymphoma) Mycobacterium avium complex or disease caused by M kansasii, disseminated
Disease caused by Mycobacterium tuberculosis, any site (pulmonary*or extrapulmonary#) Disease caused by Mycobacterium, other species, or unidentified species, disseminated
Pneumocystis jiroveci (formerly carinii) pneumonia Pneumonia, recurrent*
Progressive multifocal leukoencephalopathy Salmonella septicemia, recurrent
Toxoplasmosis of brain (encephalitis) Wasting syndrome caused by HIV infection#
Additional illnesses that are AIDS defining in children, but not adults Multiple, recurrent bacterial infections#
Lymphoid interstitial pneumonia/pulmonary lymphoid hyperplasia
HIV Genes and Proteins
Peterlin et al Nature Reviews Immunol 3; 97-107 (2003)
HIV Structure
exhiv.chat.ru
Fusion of HIV using CD4 and chemokine receptor
HIV Life Cycle
Peterlin et al Nature Reviews Immunol 3; 97-107 (2003)
1. HIV enters via CD4
2. RNA reverse transcribed into DNA
3. DNA integrates into host genome
4. Latency?
5. Replication produces proteins
6. Proteins assemble into new viruses
Treating HIV Infection
Peterlin et al Nature Reviews Immunol 3; 97-107 (2003)
Three main sites for HIV drugsA. Reverse transcriptaseB. HIV proteaseC. HIV entryD. Integration
A.
C.B.
Main classes of HIV drugs
1. Nucleoside analogues (zidovudine) - A2. Non-nucleoside (nevaripine) - A3. Protease Inhibitors (indinavir) - B4. Chemokine Receptor Antagonists (maraviroc) – C5. Fusion Inhibitors – (enfuvirtide) - C6. Integrase Inhibitors - (elvitegravir) - D
D.
Role of DCs in HIV Infection
Nature Reviews Immunology 2; 957-965 (2002)
Lymphatic System
The Kinetics of HIV Disease Progression
0 1 3 6 12 24 36 48 60 72 84 96 108 120 132 1440
2
4
6
8
10
12
CD4+ T cells
HIV CTL
Neut Ab
HIV viral load
Death
Time Post Infection (Months)
Re
lati
ve
Va
lue
s
Acute Phase
AsymptomaticPhase
AIDS
Alimonti, Ball & Fowke, J GenVirol (in press)
Outline
Epidemiology of the disease
HIV Disease HIV replication Why does HIV cause immunodeficiency? What does the CD4+ T cell do?
Three types of T-helper cell. How does HIV decrease CD4+ levels? Apoptosis in HIV infection HIV Resistance
Mechanisms of Resistance
Hallmark of HIV disease
• Loss of CD4+ T cells from peripheral blood
What is the role of CD4+ T cells in the immune response?
CD4+ T helper cells: Conductors of the Immune System
Subsets of CD4+ T helper cells
APC+Ag
IL-2IL-12 IL-4
IL-4 IFN-
Dominant Cellular Immunity
Dominant Humoral Immunity
IFN- IL-4IL-5
IL-13IL-4, IL-10
IFN-
Naive CD4+ Tcell
Activated CD4+ Tcell
Th2Th1
T reg
Suppression
Th17
The Kinetics of HIV Disease Progression
0 1 3 6 12 24 36 48 60 72 84 96 108 120 132 1440
2
4
6
8
10
12
CD4+ T cells
HIV CTL
Neut Ab
HIV viral load
Death
Time Post Infection (Months)
Re
lati
ve
Va
lue
s
Acute Phase
AsymptomaticPhase
AIDS
Alimonti, Ball & Fowke, J GenVirol (in press)
Mechanisms for CD4+ cell decline
•Direct•Synctia formation (cell-cell fusion)•Direct viral cytopathic effect
•Indirect•Apoptosis/PCD
Activation Induced Cell Death•Autoimmune mechanisms
Homology of viral proteins to self antigens•Superantigen-mediated deletion
Viral proteins acting as superantigens•Type 1/Type 2 cytokine dysregulation
CD4 APC
Time 0 hrs
Time 6 hrs
CD8 CD4
9.2 0
090.8
25.8 0
074.2
8.212.3
079.5
0
49.528.3
22.2
CD8 CD4
Detection of Apoptosis
Relationship Between Apoptosis and CD4 or Virus Levels
0 100 200 300 400 500 600
HIV Titre (KEq/ml)
0
20
40
60
80
100% Apoptotic Nuclei
Spontaneous Mitogen
0 200 400 600 800 1000 1200 1400
CD4 Counts
0
20
40
60
80
100
-20
% Apoptotic Nuclei
Spontaneous Mitogen
Fowke et al AIDS 11:1016, 1997
Apoptosis in HIV infection
Mechanisms:
•gp120/41 - CD4 crosslinking, ↓ BCL-2, ↑CD95(Fas)/CD95L(FasL)•gp120 induction of syncytia•HIV protease activates caspase 8 and ↓ BCL-2•Tat – ↑ Caspase 8, Fas, FasL and ↓BCL-2•Vpr – membrane disruption of mitochondrion•Nef - myristylated N-terminus interacts with TCR and leads to upregulation of Fas/L•Fas/FasL – altered in T cells and monocytes due to nef•AICD – increased Fas/FasL
CD4’s Role in Signal transduction
T-Cell Activation
gp120-induced CD4-crosslinking
Uninfected CD4 T cell CD4 cross-linking activates lck↑ CD95(Fas)↓ BCL-2
apoptosis
= CD4
=sgp120
=p56lck
=P-p56lck
HIV nef effects on CD4 and MHC I
Peterlin et al Nature Reviews Immunol 3; 97-107 (2003)
Outline
Epidemiology of the disease
HIV Disease HIV replication Why does HIV cause immunodeficiency? What does the CD4+ T cell do?
Three types of T-helper cell. How does HIV decrease CD4+ levels? Apoptosis in HIV infection HIV Resistance
Mechanisms of Resistance
Kenya
Nairobi
Kisumu
•HIV prevalence•14% in 1997•6.7 in 2003•8.5% in 2007•6.2% in 2011 in adults
Source UNAIDS
Nairobi
UM’s contribution to HIV/AIDS
1. Heterosexual transmission of HIV
2. Mother to child transmission – incl breast milk
3. STI’s as significant risk factors
4. Directed interventions prevent new infections
5. Male circumcision clinical trial showed protection
6. HIV resistance
Majengo Clinic
Majengo Clinic
•Focus•The health of commercial sex workers
•Provides•Primary health care•Trained physicians, nurses, pharmacist•STI treatment•HIV prevention education•Condoms (male and female)•HIV counseling •HIV treatment
•Research
Majengo Clinic Staff
Photos by Rich Lester & Keith Fowke
Majengo Clinic Clients
Majengo Clinic Baraza 2009
Photos by Rich Lester
Nairobi Sex Worker Study Pumwani cohort
• Est. in 1985, open cohort > 4000 women enrolled• Average 4 clients/day• most are HIV+ at entry, those not seroconvert within 2 yrs
• ~110 uninfected despite up to 500 unprotected exposures• Exposure or co-factor determinants not different
• HIV resistance defined as:
1. No evidence of HIV infection
2. Still active in sex work
3. Followed in cohort for >7 years
HIV Resistance – Data Summary
• Resistance is not:▫ Absolute▫ Differing sexual practices▫ Seronegative infection▫ Decreased susceptibility to other infections▫ Coreceptor polymorphisms▫ enhanced -chemokine production
• Resistance associates with:▫ HIV-specific cellular immunity
CTL, CD4+ T cell responses in PBMC (Fowke et al.) Mucosal CTL responses (Kaul et al.) Qualitatively distinct responses strong proliferation, weak IFN (Alimonti et al.)
▫ Genetic basis for resistance Familial association (Kimani) Kindred of HIV-R more likely to remain HIV-negative (Kimani, Ball) Polymorphisms associated with resistance, e.g. IRF-1 (Ji, Ball)
• Few data linking immune and genetic associations
HIV Resistance – Data Summary
• Resistance is not:▫ Differing sexual practices▫ Seronegative infection▫ Decreased susceptibility to other infections▫ Coreceptor polymorphisms▫ enhanced -chemokine production
• Resistance is:▫ HIV-specific cellular immunity
CTL, CD4+ T cell responses in PBMC (Fowke et al.) Mucosal CTL responses (Kaul et al.) Qualitatively distinct responses strong proliferation, weak IFN (Alimonti et al.)
▫ Genetic basis for resistance Familial association (Kimani) Kindered of HIV-R more likely to remain HIV-negative (Kimani, Ball) Polymorphisms associated with resistance, e.g. IRF-1 (Ji, Ball)
• Few data linking immune and genetic associations
Hypotheses:
Resistance is mediated by immune and genetic components
HIV-R women will have HIV-specific T cell responses
HIV-R women will have high levels of immune activation to fight infection
Immune Environment of Resistants is Different than HIV+
p0.001
p=NS
p0.012
p=NS
p=0.002
p=NS
Resistant
HIV-specific CD4+ T cells in HESN
Fowke et al Immunology and Cell Biology, 2000
Qualitatively Distinct Responses in RESBetter Proliferative Responses
Alimonti et al JID, 2005
0
2
4
6
8
10
res pos neglo
cpm
cpm
(X10
3)
ESN HIV+ HIVNlow
p24 peptides
p=0.002
n = 6 12 1
0
2
4
6
8
10
res pos neglo
cpm
cpm
(X10
3)
ESN HIV+ HIVNlow
p24 peptides
p=0.002
n = 6 12 1
0
2
4
6
8
10
res pos neglo
cpm
cpm
(X10
3)
RES HIV + HIV Nlow
p24 peptides
p=0.002
n = 6 12 1
TCM higher in Resistants
% o
f CD
4+T C
ells
Resistants – CD4+ T cell Subset Distribution
CD4 Naï
ve
CD4 Tcm
CD4 Tem
CD4 Tem
/td
0
10
20
30
40
50
60 p<0.001 p=0.001
p<0.001
% o
f CD
4+T C
ells
Resistants – CD4+ T cell Subset Distribution
CD4 Naï
ve
CD4 Tcm
CD4 Tem
CD4 Tem
/td
0
10
20
30
40
50
60
% o
f CD
4+T C
ells
Resistants – CD4+ T cell Subset Distribution
CD4 Naï
ve
CD4 Tcm
CD4 Tem
CD4 Tem
/td
0
10
20
30
40
50
60 p<0.001 p=0.001
p<0.001
Resistants- CD8+ T cell Subset Distribution
CD8 Nai
ve
CD8 Tcm
CD8 Tem
CD8 Tem
/td
0
10
20
30
40
50
60
% o
f CD
8+T C
ells p<0.001
p=0.007
p<0.001
Resistants- CD8+ T cell Subset Distribution
CD8 Nai
ve
CD8 Tcm
CD8 Tem
CD8 Tem
/td
0
10
20
30
40
50
60
% o
f CD
8+T C
ells
Resistants- CD8+ T cell Subset Distribution
CD8 Nai
ve
CD8 Tcm
CD8 Tem
CD8 Tem
/td
0
10
20
30
40
50
60
% o
f CD
8+T C
ells p<0.001
p=0.007
p<0.001
Tcm
as %
of T
otal
C
D4+
T C
ells
Group Differences in CD4+ Tcm
Resis
tants
n=8
ML n
ew n
eg
n=12
MCH n
eg
n=13
ML n
ew n
eg+
MCH n
eg
n=25
0
10
20
30
40
50
60 p = 0.031p = 0.036
Tcm
as %
of T
otal
C
D4+
T C
ells
Group Differences in CD4+ Tcm
Resis
tants
n=8
ML n
ew n
eg
n=12
MCH n
eg
n=13
ML n
ew n
eg+
MCH n
eg
n=25
0
10
20
30
40
50
60 p = 0.031p = 0.036
Tcm
as %
of T
otal
C
D8+
T C
ells
Group Differences in CD8+ Tcm
Resis
tants
n=11
ML n
ew n
eg
n=18
MCH n
eg
n=11
ML n
ew n
eg+
MCH n
eg
n=29
0
10
20
p = 0.049p = 0.038
Tcm
as %
of T
otal
C
D8+
T C
ells
Group Differences in CD8+ Tcm
Resis
tants
n=11
ML n
ew n
eg
n=18
MCH n
eg
n=11
ML n
ew n
eg+
MCH n
eg
n=29
0
10
20
Tcm
as %
of T
otal
C
D8+
T C
ells
Group Differences in CD8+ Tcm
Resis
tants
n=11
ML n
ew n
eg
n=18
MCH n
eg
n=11
ML n
ew n
eg+
MCH n
eg
n=29
0
10
20
p = 0.049p = 0.038
A
C D
B
% o
f CD
4+T C
ells
Resistants – CD4+ T cell Subset Distribution
CD4 Naï
ve
CD4 Tcm
CD4 Tem
CD4 Tem
/td
0
10
20
30
40
50
60 p<0.001 p=0.001
p<0.001
% o
f CD
4+T C
ells
Resistants – CD4+ T cell Subset Distribution
CD4 Naï
ve
CD4 Tcm
CD4 Tem
CD4 Tem
/td
0
10
20
30
40
50
60
% o
f CD
4+T C
ells
Resistants – CD4+ T cell Subset Distribution
CD4 Naï
ve
CD4 Tcm
CD4 Tem
CD4 Tem
/td
0
10
20
30
40
50
60 p<0.001 p=0.001
p<0.001
Resistants- CD8+ T cell Subset Distribution
CD8 Nai
ve
CD8 Tcm
CD8 Tem
CD8 Tem
/td
0
10
20
30
40
50
60
% o
f CD
8+T C
ells p<0.001
p=0.007
p<0.001
Resistants- CD8+ T cell Subset Distribution
CD8 Nai
ve
CD8 Tcm
CD8 Tem
CD8 Tem
/td
0
10
20
30
40
50
60
% o
f CD
8+T C
ells
Resistants- CD8+ T cell Subset Distribution
CD8 Nai
ve
CD8 Tcm
CD8 Tem
CD8 Tem
/td
0
10
20
30
40
50
60
% o
f CD
8+T C
ells p<0.001
p=0.007
p<0.001
Tcm
as %
of T
otal
C
D4+
T C
ells
Group Differences in CD4+ Tcm
Resis
tants
n=8
ML n
ew n
eg
n=12
MCH n
eg
n=13
ML n
ew n
eg+
MCH n
eg
n=25
0
10
20
30
40
50
60 p = 0.031p = 0.036
Tcm
as %
of T
otal
C
D4+
T C
ells
Group Differences in CD4+ Tcm
Resis
tants
n=8
ML n
ew n
eg
n=12
MCH n
eg
n=13
ML n
ew n
eg+
MCH n
eg
n=25
0
10
20
30
40
50
60 p = 0.031p = 0.036
Tcm
as %
of T
otal
C
D8+
T C
ells
Group Differences in CD8+ Tcm
Resis
tants
n=11
ML n
ew n
eg
n=18
MCH n
eg
n=11
ML n
ew n
eg+
MCH n
eg
n=29
0
10
20
p = 0.049p = 0.038
Tcm
as %
of T
otal
C
D8+
T C
ells
Group Differences in CD8+ Tcm
Resis
tants
n=11
ML n
ew n
eg
n=18
MCH n
eg
n=11
ML n
ew n
eg+
MCH n
eg
n=29
0
10
20
Tcm
as %
of T
otal
C
D8+
T C
ells
Group Differences in CD8+ Tcm
Resis
tants
n=11
ML n
ew n
eg
n=18
MCH n
eg
n=11
ML n
ew n
eg+
MCH n
eg
n=29
0
10
20
p = 0.049p = 0.038
% o
f CD
4+T C
ells
Resistants – CD4+ T cell Subset Distribution
CD4 Naï
ve
CD4 Tcm
CD4 Tem
CD4 Tem
/td
0
10
20
30
40
50
60 p<0.001 p=0.001
p<0.001
% o
f CD
4+T C
ells
Resistants – CD4+ T cell Subset Distribution
CD4 Naï
ve
CD4 Tcm
CD4 Tem
CD4 Tem
/td
0
10
20
30
40
50
60
% o
f CD
4+T C
ells
Resistants – CD4+ T cell Subset Distribution
CD4 Naï
ve
CD4 Tcm
CD4 Tem
CD4 Tem
/td
0
10
20
30
40
50
60 p<0.001 p=0.001
p<0.001
Resistants- CD8+ T cell Subset Distribution
CD8 Nai
ve
CD8 Tcm
CD8 Tem
CD8 Tem
/td
0
10
20
30
40
50
60
% o
f CD
8+T C
ells p<0.001
p=0.007
p<0.001
Resistants- CD8+ T cell Subset Distribution
CD8 Nai
ve
CD8 Tcm
CD8 Tem
CD8 Tem
/td
0
10
20
30
40
50
60
% o
f CD
8+T C
ells
Resistants- CD8+ T cell Subset Distribution
CD8 Nai
ve
CD8 Tcm
CD8 Tem
CD8 Tem
/td
0
10
20
30
40
50
60
% o
f CD
8+T C
ells p<0.001
p=0.007
p<0.001
Tcm
as %
of T
otal
C
D4+
T C
ells
Group Differences in CD4+ Tcm
Resis
tants
n=8
ML n
ew n
eg
n=12
MCH n
eg
n=13
ML n
ew n
eg+
MCH n
eg
n=25
0
10
20
30
40
50
60 p = 0.031p = 0.036
Tcm
as %
of T
otal
C
D4+
T C
ells
Group Differences in CD4+ Tcm
Resis
tants
n=8
ML n
ew n
eg
n=12
MCH n
eg
n=13
ML n
ew n
eg+
MCH n
eg
n=25
0
10
20
30
40
50
60 p = 0.031p = 0.036
Tcm
as %
of T
otal
C
D8+
T C
ells
Group Differences in CD8+ Tcm
Resis
tants
n=11
ML n
ew n
eg
n=18
MCH n
eg
n=11
ML n
ew n
eg+
MCH n
eg
n=29
0
10
20
p = 0.049p = 0.038
Tcm
as %
of T
otal
C
D8+
T C
ells
Group Differences in CD8+ Tcm
Resis
tants
n=11
ML n
ew n
eg
n=18
MCH n
eg
n=11
ML n
ew n
eg+
MCH n
eg
n=29
0
10
20
Tcm
as %
of T
otal
C
D8+
T C
ells
Group Differences in CD8+ Tcm
Resis
tants
n=11
ML n
ew n
eg
n=18
MCH n
eg
n=11
ML n
ew n
eg+
MCH n
eg
n=29
0
10
20
p = 0.049p = 0.038
A
C D
B
S Koesters
Two-phase model of HIV-resistance
Mucosal
Assessment of T cell Function
• T cell functional assays▫ Cytokine production
▫ Cellular activation markers
• Gene expression analysis▫ Purified CD4+ T cells
9 Res, 9 High-risk negatives
▫ Whole Blood 23 Res, 19 Low-risk negatives
▫ Used Affymetrix U133 Plus 2.0
Res Negs
CD4 T cellsCD4 T cells Whole BloodWhole BloodGene expression profiling in HIV ResistantsGene expression profiling in HIV Resistants
ResNegResNeg
McLaren et al JID 2010
Whole Blood
ResNegResNeg T cell receptor signaling pathway:
Reproduced with permission www.biorag.org
T cell receptor signaling
CD4+
whole blood
Zap70
Proteasome
Stau1
Kif22PP1NF-κB
CypA
http://www.tibotec.com
HIV Replication
Assessment of T cell Function
• T cell functional assays▫ Cytokine production
▫ Cellular activation markers
• Gene expression analysis▫ Purified CD4+ T cells
9 Res, 9 High-risk negatives
▫ Whole Blood 23 Res, 19 Low-risk negatives
▫ Used Affymetrix U133 Plus 2.0
Baseline Cytokine production
Resistant Negative
Resistants have normal recall responses
• Differences between HIV-R and HIV-N not observed after stimulation• HIV-R women have normal recall responses but show lower baseline immune
activation
HIV Replicates Better in an Activated Cell
Peterlin et al Nature Reviews Immunol 3; 97-107 (2003)
Baseline T cell activation
• HIV replicates better in activated T cells
• HIV-R have fewer activated (CD69+) CD4+ and CD8+ T cells
Card et al JID 2009
Immune Quiescence in HIV resistance
• Lower overall gene expression, CD4+ T cells and whole blood
• Lower gene expression in HIV and T cell receptor pathways
• Lower resting PBMC cytokine production
• Lower level of cellular activation on T cell
• Normal Antigen recall function – not immune suppression
• OVERALL immune cells seem to be resting or quiescent
• Termed this phenotype Immune Quiescence
Evidence of IQ in other cohorts
• Amsterdam cohort of HIV-R MSM (Koning et. al. J Immunol. 2005)
– ↓ frequencies of activated (HLA DR, CD38, CD70) CD4+ T cells and proliferating (Ki67) CD4+ and CD8+ T cells
• Abijan cohort of HIV-R CSW (Jennes et. al. Clin Exp. Immunol. 2006)
– ↓ CD69, IFN, MIP-1 and RANTES following allo-stimulation
• Hemophiliacs, highly exposed (Salkowitz et al Clin Imm 2001)
– Low immune activation in exposed uninfecteds• Discordant couples in Central African Republic (Begaud et. al. Retrovirology 2006)
– ↓ frequencies of activated (HLA DR, CCR5) CD4+ T cells
– Reduced HIV susceptibility in unstimulated PBMC
– Differences not observed when PHA stimulated cells were infected
• However, Clerici shows increased TLR activity associated with protection
T regs as IQ mediators
• HIV-R have elevated frequencies of regulatory T cells
Two phase model of HIV resistance
What is driving Immune Quiescence?
Systemic Tregs correlate
? Transcriptional Factors
? Mucosal Factors
Two-phase model of HIV-resistance
Mucosal
HIV replication in quiescent CD4+ Tcells?
HIV replication in quiescent cells
• Card et al Plos One 2012
HIV replication in quiescent cells
• Individuals vary in their ability to support HIV replication
• Ex vivo levels of T cell activation correlate with a ability to support HIV replication
• In the infected cultures, infected cells are more highly activated
• Among the infected cells, T regs are enriched
Evidence for IQ at mucosal surface?
Cervical Lavage Chemokine Levels
• Julie Lajoie, et al Mucosal Immunology 2012
Fewer Target cells at Mucosa
C. Card
Cervical Lavage Cervical Biopsy
K. Broliden
Mucosal Immune Quiescence
• HESN have fewer CD4+CCR5+ T cells
• HESN have lower levels of the inflammatory cytokine IL-1a
• HESN have lower levels of the T cell migratory factors MIG and IP-10.
Mucosal IQ model
Role of Immune Quiescence in HESN
• Evidence of HIV-specific CD4+ and CD8+ T cell responses
• Lower levels of T cell activation• Normal ability to respond to antigen• Quiescent cells do not support HIV
replication as well• IQ phenotype extends to genital mucosa
• Fewer target cells – lower susceptibility to HIV
Two-phase model of HIV-resistance
Mucosal
1.Vaccinate against HIV•try to drive TCM •No exposure during activation phase
1.Vaccinate against HIV•try to drive TCM •No exposure during activation phase
2.Maintain a quiescent phenotype at mucosa•Stimulate mucosal Tregs •Microbicides with anti-inflammatory activity
2.Maintain a quiescent phenotype at mucosa•Stimulate mucosal Tregs •Microbicides with anti-inflammatory activity
Thanks
Collaborators The Funders• Frank Plummer• Blake Ball• Ma Luo • Joshua Kimani• Walter Jaoko• Ruey Su• Aida Sivro• Elijah Songok• Paul McLaren• Catherine Card• Charles Wachihi• Majengo Clinic staff• MCH Clinic staff
• MHRC• CIHR• BM Gates Foundation
UNIVERSITY OF NAIROBI
Ongoing studies
1. Evaluation of Immune Quiescence at the genital mucosaa) Activation phenotypeb) Gene expression analysis
2. In vitro HIV infections of unstimulated PBMC
3. Use drugs to induce IQ in FGT
4. Validate in other cohorts
Thanks
Collaborators The Funders• Frank Plummer• Keith Fowke• Blake Ball• Ma Luo • Joshua Kimani• Walter Jaoko• Ruey Su• Aida Sivro• Elijah Songok• Paul McLaren• Catherine Card• Charles Wachihi• Majengo Clinic staff• MCH Clinic staff
• MHRC• CIHR• BM Gates Foundation
UNIVERSITY OF NAIROBI
Laboratory of Viral Immunology
Winnipeg and Nairobi Research Teams
Majengo Clinic Staff and Clients
Photo used with permission
The Hope for an HIV Vaccine
Take home message
1. HIV infects and kills the central cell of the immune system
2. HIV proteins can either promote or block apoptosis
3. HIV resistance is multi-factoral
4. Genetic, cell-mediated and immune quiescence mechanisms involved in resistance