Potential mucosal immune mechanisms for increased HIV susceptibility in women

infected by Herpes simplex type 2

Dr. Anu Rebbapragada

University of Toronto

Anu Rebbapragada, Charles Wachihi, Chris Pettengell, Sherzana Sunderji, Sanja Huibner, Anthony Sheung, George Moussa, Anthony

Mazzuli, Walter Jaoko, Blake Ball, Keith Fowke, Francis Plummer and Rupert Kaul

HIV infects >40 million globally, mostly through sexual transmission, and most are now in women

Mucosal vaccine and microbicide trials will need to monitor genital immunology and must consider that:

•Globally, genital co-infections are “the norm”

•CMV infects 50-90% of adults - more in Sub Saharan Africa (SSA)

•HSV2 infects 20-60% of adults - more in SSA, more in women

•Bacterial vaginosis, HPV, trichomoniasis: also very common

Interactions at the Mucosal Front

General population:• associated with a >3 fold increase in HIV acquisition by women, even in the absence of genital ulcers (Freeman E, 2006; Wald A, 2004)

•In Sub-saharan African Women: HSV2 prevalence ~ 50%

HIV and HSV2A Dangerous Liaison

Core Transmitter Groups:

• HSV2 has been associated with 6-fold increase in HIV acquisition in Nairobi female sex workers (FSWs; JAMA, 2004)

• In FSWs: HSV2 prevalence group exceeds 75%

HSV2 may drive HIV transmission

Wald A, Herpes. 2004.

In regions of high HSV2 seroprevalance:

• Mathematical modeling predicts 50% of new HIV cases directly attributed to HSV2

Research Questions

How does HSV2 infection increase HIV acquisition?

• Is this simply due to epithelial micro-ulceration?

• Or through negative effects on the female genital tract (FGT) immune milieu?

What is the potential immune basis of enhanced HIV susceptibility?

HSV2 Study: Mucosal Sampling

For all women:

• Cytokines/chemokine levels in CVL by CBA (BD)

• Immune Genes expression levels: QPCR (cytobrush)

• Endocervical cell populations by flow cytometry (scraper)• Mucosal Lymphocytes: CCR5+/CD69+ CD4+ T cells

• Mucosal Dendritic cells: CD1a+ iDC, DC-SIGN+ iDC, TLR9+ iDC

• HIV, CMV serology; HSV2 serology (Kalon)

• HSV2 DNA from swab (Artus)

• CMV DNA from CVL (Artus)

• HIV-1 RNA from swab (Versant)

• Cross-sectional survey during 2004-2005

• Female sex workers from Pumwani, Nairobi

102 FSWs screened for possible study enrollment

91 FSWs enrolled

11 FSWs taking ARV excluded

HIV uninfected (N = 55) HIV infected (N = 36)

HSV2 infected

(42/55, 76%)

HSV2 uninfected

(13/55, 24%)

HSV2 infected

(36/36, 100%)

**LR = 14.5P<0.001

0/42 (0%)

Shedding HSV2

10/36 (26%)

Shedding HSV2

**LR = 16.5P<0.001

Endocervical Cell Populations

CD1a

DC

-SIG

N

1 0

0

1 0

1

1 0

2

1 0

3

1 0

4

1 0

0

1 0

1

1 0

2

1 0

3

1 0

4

1 0

0

1 0

1

1 0

2

1 0

3

1 0

4

1 0

0

1 0

1

1 0

2

1 0

3

1 0

4

CD3

CD

4

Autofluorescence

0 5 0 1 0 0 1 5 0 2 0 0 2 5 0

1 0

0

1 0

1

1 0

2

1 0

3

1 0

4

Sid

e sc

atte

r

Forward scatter

Granular Cells

Lymphocytes

Impact of HSV2 status on FGT immune milieu

Lymphocyte Populations

CD4+ CCR5+CD4+

CD69+CD4+

%CD69+

* ****

0

500

1000

1500

2000

20%

40%

60%

80%

0%

HSV2 uninfected

HSV2 infected

Immune cell populations

Dendritic Cell Populations

Impact of HSV2 status on FGT immune milieu

**CD1a+ DC-SIGN+

iDC%DC-SIGN+

iDC

*0

20%

40%

60%

80%

0%

HSV2 uninfected

HSV2 infected

20000

Immune cell populations

40000

60000

80000

20%

One possible model for mucosal HIV-HSV2 synergy

HSV2 infection

DC-SIGN+ iDCCCR5+ CD4 T cells

HSV2 reactivation& shedding

HIV infection

DC-SIGN+ iDC TLR9+ iDC

HSV2 proteinstransactivate HIV-LTR

HIV shedding

Conclusions

1. Powerful epidemiologic synergy between HIV and HSV2:

• HIV infected FSWs more likely to be HSV2 infected and shed HSV2.

4. Novel Strategies to reduce HIV transmission:

• Microbicides targeting DC-SIGN and/or CCR5

3. Interaction between HIV and HSV2 in the genital mucosa

• Powerful immunological negative synergy

2. HIV target cells increased in FGT of HSV2 infected FSWs:

• 10 fold increase in DC-SIGN+ CD1a+ immature dendritic cells

• 3 fold increase in CCR5+ CD4+ T cells

Dr.Rupert Kaul

Kaul lab: Prameet Sheth, Chris Pettengel, Sanja Huibner, Bolette Bossen, Kamnoosh Shahabi, Sherzana Sunderji, Anthony Sheung

University of Toronto: Mario Ostrowski, Sandy Der

University of Manitoba: Blake Ball, Keith Fowke, Frank Plummer

University of Nairobi: Joshua Kimani, Charles Wachihi, Elizabeth Ngugi, Walter Jaoko, Jane Kamene, Nyakio Chinga, Anne Miangi

Funding: NIH, CIHR, CANVAC, Canada Research Chair