1. XVII International AIDS Conference
Effects of HIV-1 Tat Protein on Trypanosomatid Replication in HIV-1-Infected Macrophages
Dumith Chequer Bou-Habib
Oswaldo Cruz Institute – Fiocruz
Rio de Janeiro, RJ
Brazil
XVII International AIDS Conference
Mexico City, August 2008

2. 35
WHO, 2003

3. 1911 Leishmania/HIV co-infection cases reported in south-western Europe by early 2001
(Desjeux & Alvar, 2003)
Brazil: 326 cases of HIV/Leishmania co-infection cases from 2000 to 2006, ~ 2% of visceral leishmaniasis reported in the country (SINAN)

4. Some clinical and laboratory findings of HIV-1/Leishmania co-infected patients
Diffuse cutaneous leishmaniasis due to parasitic dissemination (ulcers containing parasites)
Chronic progress and relapses of leishmaniasis
Increased replication of HIV-1 and Leishmania
High levels of serum cytokines (IL-4, IL-6, IL-10)
Decreased IFN- levels

5. At the cellular level…

6. HIV-1/Leishmania
co-infected
macrophages
“Something happens”
Increases Leishmania
replication

7. Tat (Trans-activator protein)
HIV-1 Genome
Tat (Trans-activator protein)
TGF-b
Adapted from Wahl et al. (2003). J Leukoc Biol 74:

8. Evaluation of Leishmania Infection
Model: HIV-1-infected Macrophages + Leishmania
Evaluation of Leishmania Infection
Endocytic Index = % of Leishmania-infected Macrophages X Mean of Parasites per Cell

9. Replication of both pathogens is augmented in
HIV-1/Leishmania co-infected macrophages
* p<0.0001
** p<0.04
Barreto-de-Souza et al. (2006)

10. HIV-1-mediated enhancement of Leishmania growth is inhibited by anti-Tat antibody
* p<0.025
* p<0.025
Barreto-de-Souza et al

11. Purified HIV-1 Tat augments Leishmania replication in macrophages
Barreto-de-Souza et al

12. HIV-1 Tat inhibits leishmanicidal effect
induced by IFN-
* p<0.035

13. TGF-1 is partially responsible for the enhancement of Leishmania growth mediated by Tat
Recombinant Tat induced TGF-b1 secretion by uninfected macrophages (p<0.002 )

14. Tat induces the expression of COX-2 enzyme and
PGE2 synthesis in human macrophages
PGE2
Med Tat
COX-2
b-actin
0.716± ± (ng/mL)
Recombinant Tat was LPS free (< 0.15 EU/mg)

15. Inhibition of the enzyme COX-2 reverts Tat effect on Leishmania growth
* p<0.02

16. Inhibition of TGF-1 abolishes PGE2 effect on
Leishmania growth
* p<0.03

17. Conclusions
Tat exacerbates Leishmania growth in macrophages co-infected with HIV-1, or infected only with Leishmania
Tat effects on Leishmania replication are mediated by:
- Induction of COX-2 and subsequent PGE2 production
- Induction of TGF-b1 secretion (probably via PGE2)
- Inhibition of leishmanicidal effect induced by IFN-

18. Induces the expression of COX-2
HIV-1 Genome
Induces the expression of COX-2
TGF-b
Adapted from Wahl et al., 2003.

19. At the cellular level…
Work in progress

20. Next question:
Could HIV-1 infection deactivate the natural microbicidal activity of human macrophages?
(Leading to an establishment/growth of a non-pathogenic protozoan?)

21. Reports of AIDS patients presenting Leishmania-like infection caused by otherwise non-pathogenic trypanosomatids
AIDS patient with a visceral lesions caused by Leptomonas pulexsimulantis (Pacheco RS et al., 1998).
AIDS patients infected by non-pathogenic trypanosomatids have been reported since the 80’s (Chicharro C & Alvar J, 2003).

22. Blastocrithidia culicis as a model for HIV-co-pathogen studies
Monoxenic trypanosomatid (entire life cycle limited to one host- hematophagous insects)
Endosymbiont-bearing trypanosomatid, containing a single bacterium/protozoan cell.
Normal human macrophages usually kill Blastocrithidia in few days (Barreto-de-Souza et al., 2008)
Some monoxenic protozoa were detected in AIDS patients (mainly Herpetomonas and Crithidia)

23. Replication of both agents is augmented in Blastocrithidia/HIV-1 co-infected macrophages
Barreto-de-Souza et al., 2008

24. HIV-1 infected Macrophage harboring B.culicis cells

25. Dividing forms of the protozoan in Blastocrithidia/HIV-1 co-infected macrophages
Barreto-de-Souza et al., 2008

26. Neutralization of Tat reduces B
Neutralization of Tat reduces B. culicis growth in HIV-1 co-infected macrophages
Barreto-de-Souza et al. 2008

27. rTat promotes Blastocrithidia growth in macrophages
Barreto-de-Souza et al. 2008

28. The increment of B.culicis growth is mediated by Tat-induced TGF-1
* p<0.05

29. Acknowledgments Oswaldo Cruz Institute/Fiocruz Federal University of
Dept. Immunology
Victor Barreto de Souza
Thalyta Medeiros
Dept. Physiology, Pharmacodinamics
Adriana R. Silva
Patrícia T. Bozza
Hugo C. Castro Faria-Neto
Federal University of
Rio de Janeiro
Dept. Immunology, IMPPG
Elvira Saraiva
Graziela J. Pacheco
Biophysics Institute, IBCCF
Cristina Motta
Reagents: NIH AIDS Reagent Program, Hemotherapy Service (HUCCF - UFRJ)
Financial Support: Papes/Fiocruz, CNPq, Faperj