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Trypanosoma cruzi-elicited CD8+ T cell-mediated
myocarditis: chemokine receptors and
adhesion molecules as potential therapeutic
targets to control chronic inflammation?

Joseli Lannes-Vieira

PhD, Titular Researcher
Laboratory of Autoimmunity and Immunoregulation,
Department of Immunology, IOC-Fiocruz.
Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brazil
Phone: 55-21-598-4609, FAX: 55-21-280-1589.

In Chagas' disease, the establishment of inflammatory processes is crucial for Trypanosoma cruzi control in target tissues and the establishment of host/parasite equilibrium. However, in about 30% of the patients inflammation becomes progressive, resulting in chronic disease, mainly characterized by myocarditis. Although several hypothesis have been raised to explain the pathogenesis of chagasic myocardiopathy, including the persistence of the parasite and/or participation of autoimmune processes [1,2], the molecular mechanisms underlying the establishment of the inflammatory process leading to parasitism control but also contributing to the maintenance of T. cruzi-elicited chronic myocarditis remain unsolved.

Trying to shed light on these questions, we have for several years been working with murine models for Chagas'disease that reproduce the acute self-resolving meningoencephalitis [3], the encephalitis resulting of reactivation described in immunodeficient individuals [4] and several aspects of the acute and chronic myocarditis [5,6]. In the present article, our results are summarized and discussed under the light of the current literature. Furthermore, rational therapeutic intervention strategies based on integrin-mediated adhesion and chemokine receptor-driven recruitment of leukocytes are proposed to control T. cruzi-elicited unbalanced inflammation.

During an infectious process, the recruitment and migration of leukocytes towards and inside a target tissue is crucial for resolving the infectious and reestablishment of homeostasis. Both recruitment and migration are multi-step processes that depend on the nature and state of activation of the leukocytes, involve pro-inflammatory cytokines, adhesion molecules and extracellular matrix (ECM) components, being co-ordinated by a mosaic of chemoattractant molecules (chemokines) [7-13].

Several studies have demonstrated that CD8+ cells are the predominant cell population in the cardiac tissue of chronic chagasic patients[14-17]. Using C3H/HeJ mice infected with the Colombiana strain of T. cruzi we showed the prevalence of CD8+ T cells (CD4:CD8 ratio of 1:3) in the inflamed heart of chronically T. cruzi-infected experimental animals. Akin chagasic patients, amastigote forms and parasite antigens were scarce in the chronically inflamed myocardium and associated with the presence of rare IL-4 producing cells, while large amounts of the pro-inflammatory cytokines IFN-g and TNF-a were detected [16,17,6].

Thus, our results led us to consider that the infection of C3H/HeJ mice with the Colombiana strain of T. cruzi reproduced several aspects of the chagasic chronic myocarditis and was an appropriate model to study the molecular mechanisms involved in the recruitment and accumulation of inflammatory cells into the cardiac tissue leading to the establishment of chronic CD8-mediated T. cruzi-elicited myocarditis. Initially, we showed that the predominance of CD8+ T cells in the cardiac tissue was not a result of the influx of the predominant cell population in the immune compartments, since during the chronic infection CD4+ cells represent the prevalent T cell population in peripheral blood and lymphoid tissues. Therefore, insight into the mechanisms participating and regulating the selective CD8+ T cell trafficking is crucial when trying to understand how T. cruzi-elicited myocarditis is established.
The requirement and functional participation of L-selectin (CD62L), leukocyte function-associated antigen 1 (LFA-1; CD11a,CD18) and very late activation antigen 4 (VLA-4; CD49d,CD29; a 4ß1) in T cell activation and migration has been extensively demonstrated in other model [18,19]. For this reason, we investigated the expression of CD62L, LFA-1 and VLA-4 on cells isolated from heart tissue, and peripheral blood of T. cruzi-infected mice. A high percentage of circulating CD8+ T cells and most of the CD4+ and CD8+ T cells present in myocardium of T. cruzi-infected animals express an activation phenotype characterized as CD62LLow, LFA-1High and VLA-4High. Interestingly, the distribution of CD4+ and CD8+ T-cells in the myocardium mirrors the frequency of cells expressing the CD62LLowLFA-1HighVLA-4High activation phenotype among CD4+ and CD8+ peripheral blood T cells. In agreement with these results, a recent study demonstrated that patients with a mild form of Chagas' disease showed a lower percentage of CD3+a4+ peripheral blood cells, in comparison with those with severe chronic cardiopathy[20]. Increased expression of ECM components particularly fibronectin (FN), a VLA-4 ligand, have been previously detected in the myocardium of T. cruzi-infected mice during the acute and chronic phases [21]. Studying Colombiana-infected C3H/HeJ mice, we confirmed this finding and showed that a fine interstitial FN mesh present in the inflamed heart involves VLA-4+ CD4+ and CD8+ T cells [6] as well as the infected and non-infected myocytes. Interestingly, the FN filamentous network present in the inflamed myocardium may function as a pathway in T cell migration process via VLA-4 interactions but may also influence T cell activation. In fact, it was demonstrated that antibodies against VLA-4 increase the anti-CD3-induced T cell adherence to FN and sinergistically induce T cell proliferation [7,19]. Then, it is reasoned to propose that interactions of VLA-4+ CD4+ and CD8+ T cells with the FN mesh present in the inflamed heart could contribute to the perpetuation of the inflammation in this tissue influencing antigen-specific T cell recognition, activation, proliferation, survival and effector activity. Consistently, besides the FN network surrounding VLA-4+ activated mononuclear cells, endothelial cells expressing vascular cell adhesion molecules 1 (VCAM-1), another VLA-4 ligand, were found in the inflamed myocardium, supporting the possibility that VLA-4-mediated interactions might be important for leukocyte entrance in the cardiac tissue, cell migration and positioning towards infected sites as well as persistence of leukocyte activation phenotype inside the inflamed heart [6].

More recently, we have demonstrated that when compared with non-infected or 7 days T.cruzi-infected animals,14 days infected mice present a large proportion of circulating CD8+ T cells expressing the VLA-4+ activation phenotype. Further, the CD8-mediated myocarditis is established on day 28 pos-infection. In this moment, most of the mononuclear cells forming focal inflammatory infiltrates surrounding T. cruzi-infected cardiomyocytes are CD8+ lymphocytes, whereas CD4+ cells constituted diffuse infiltrates (APMP Marino and J Lannes-Vieira, unpublished results). Altogether, these results led us to speculate that the predominance of CD8+ T cells in the inflamed myocardium of T. cruzi-infected host might result of the predominance of CD8+ expressing the activated phenotype (CD62LLowLFA-1HighVLA-4High) in peripheral blood which is established during the early acute infection and persisted during the chronic disease. The use of immunomodulators such as IFN-ß able to downregulate the expression of VLA-4 or monoclonal antibodies and antagonists specific for adhesion molecules are being proposed and successfully used to ameliorate inflammatory processes [22,23]. Therefore, our results point to the possibility that adhesion molecules may constitute a logic target to control the inflammation elicited by T. cruzi infection. In this context, anti-VLA-4 monoclonal antibodies successfully blocked the ex-vivo adhesion of peripheral blood activated T cells to blood vessels of central nervous system slices obtained from T. cruzi-infected mice. Moreover, anti-VLA-4 antibodies selectively inhibited the migration of activated T cells to the brain tissue of T. cruzi-infected mice [24]. Presently we are testing the participation of VLA-4-mediated interactions in the establishment of T. cruzi-elicited acute and chronic myocarditis, thus paving the way for the development of a VLA-4-based therapy for T. cruzi-elicited myocarditis.

Our previous report showing that a CD8-mediated encephalitis is restricted to the acute phase in the C3H/He mice infected Colombiana strain of T. Cruzi [3], however, provides evidence that the persistence of chronic myocarditis with the predominance of CD8+ T cells does not only result from the activation phenotype expressed by peripheral blood CD8+ T cells, although it may represent a requirement for the entrance of these cells into the target tissue. Thus, other factors present in the cardiac environment could also be involved in the migration, retention and activation of inflammatory cells leading to perpetuation of the myocarditis in these T. cruzi-infected mice.

It is considered that the cytokines produced in the heart tissue during the initial immune response will influence the subsequent immune reaction. In this vein, our data indicate that TNF-a, IFN-g and IFN-g-induced chemokines RANTES (regulated upon activation, normal T cell expressed and secreted), MIG (monokine induced by IFN-g) and CRG-2/IP-10 (cytokine response gene 2/interferon g-inducible protein 10), as well as JE/MCP-1 (monocyte chemoattractant protein-1) and MIP1-a (macrophage inflammatory protein 1 a) were found to be the dominant cytokines expressed in situ during acute infection, persisting during the chronic phase of T. cruzi-elicited myocarditis and may contribute to the intense recruitment of activated T cells [6].

Previous report showed that during Listeria monocytogenes infection, CD8+ T cells are the main source of MIP-1a and that this chemokine has the ability to preferentially recruit the CD8+ T cell subpopulation[25]. In addition, in vitro experiments showed that MIP-1a preferentially induces chemotaxis of CD8+ T lymphocytes, whereas MIP-1ß is related to the preferential recruitment of CD4+ T cells [26]. Altogether, these findings led us to propose that IFN-g and IFN-g-elicited RANTES, JE/MCP-1 and MIP-1a chemoattractants present in the inflamed heart of Colombiana-infected C3H/HeJ mice create a favourable environment for selective and preferential migration of CD8+ T cells towards this tissue, leading to a CD8-mediated myocarditis [6].

The pro-inflammatory cytokines TNF-a and IFN-g play a major role controlling tissue parasitism during T. cruzi infection[27,28]. These cytokines are present in the inflamed heart of chronic chagasic patients[14,17], and acute and chronic experimentally T. cruzi-infected mice[29,5,6], suggesting that besides contributing to parasitism control they could be also involved in the maintenance of chronic myocarditis[27,28]. Recently we showed that the heart and central nervous system are the main sites of reactivation of T. cruzi infection in mice lacking functional genes for IFN-g and IL-12, respectively.

This reactivation was characterized by intense inflammation accompanied by remarkable enhancement in parasitism, particularly resembling the parasite-elicited mass encephalitis often found in chronic chagasic patients with AIDS[30]. Importantly, during reactivation of infection the inflammatory processes in the central nervous system from IL-12 knockout mice were mostly devoid of CD8+ T cells and mainly composed of polymorphic nuclear cells, macrophages and CD4+ T cells, whereas in the heart CD8+ T cells predominate over CD4+ T cells. Consistent with the hypothesis that CD8+ T lymphocytes are the major source of IFN-g and IFN-g-inducible chemokines that orchestrate the preferential CD8 migration during T. cruzi infection, we found IFN-g producing cells in the heart, but not in the central nervous system of these animals (V Michailowsky and J Lannes-Vieira, unpublished results).
Thus, considering the importance of CD8+ T cells in resistance to T. Cruzi[31,32], the increased susceptibility to parasite replication and mass encephalitis could be explained by the lack of CD8 T cell migration and local production of IFN-g and IFN-g-inducible chemokines in IL-12 deficient mice. Our results also showed that in contrast to IFN-g knockout mice, splenocytes from IL-12 knockout mice infected T. cruzi produced low levels of IFN-g upon stimulation with parasite antigens. Thus, our data suggest that the level of interferon-g deficiency is a major determinant of the site of reactivation of T. cruzi infection in immunocompromised host4.
Chemokines are small (8-14 kDa) inducible cytokines that recognize a large group of 7 transmembrane-spanning G-protein-coupled serpentine receptors displayed on the leukocyte surface and are involved in normal trafficking of leukocytes to both lymphoid and nonlymphoid organs and recruitment of these cells to sites of injury and infection. Moreover, chemokines also appear to affect several other immunological phenomena, and play an important role in immune regulation, mediating leukocyte activation, costimulation and differentiation during innate and adaptive immune responses [11-13].

Recent studies have shown that human macrophages in vitro infected with T. Cruzi[33], and in vivo and in vitro T. cruzi-infected peritoneal macrophages and cardiomyocytes produce RANTES, MIP-1a and JE/MCP-1 and respond to these chemokines increasing T. cruzi uptake, enhancing nitric oxide production and controlling parasite replication [34,35]. Further, using knockout mice infected with T. cruzi we showed that both IFN-g and TNF-a are essential for the production of RANTES and MIP-1a, respectively [36]. Also, IFN-g enhanced the in vitro production of RANTES and IP-10 by macrophages infected with T. cruzi or treated with glycosylphosphatidylinositol-anchored mucin-like glycoproteins of trypomastigotes (tGPI-mucins) [36,5]. Thus, it is possible that IFN-g-induced chemokines present in the cardiac tissue o T. cruzi-infected individuals could also participate in parasitism control.

Considering a general model for Chagas' pathogenesis, the results discussed above suggest that the predominance of CD8+ T cells in the myocardium of T. cruzi-infected individuals reflects the profile of adhesion molecules and chemokine receptors displayed by the circulating CD8+ T cells and point to the possibility that multiple IFN-g-inducible molecules present in the inflamed tissue contribute to the genesis and maintenance of T. cruzi-induced myocarditis.

The corollarium of this hypothesis is that activated CD8+ T cells present in the inflamed heart as well as a large proportion of circulating CD8 lymphocytes of T. cruzi-infected individuals differentially bear CC chemokines receptors such as CCR1, CCR3, CCR5 [37], in comparison with CD4+ T cells. Interestingly, recent reports show that the expression of CCR5 is increased on CD3+CD8+ peripheral blood T cells obtained from patients with mild cardiomyopathy compared with uninfected individuals or patients with severe disease [38]. In agreement with this finding, it has been shown that a CCR5 promoter point mutation was significantly increased in asymptomatic patients compared with patients with cardiomyopathy [39]. Moreover, it has been reported that most CD8+ T cells present in the heart of T. cruzi-infected mice express CCR5 in heart [40].

Altogether, these results and our data discussed above led us to consider that CC chemokines, specially RANTES and MIP-1a, and CC receptors, mainly CCR5, could be involved in differential cell migration and pathogenesis of T. cruzi-elicited CD8-mediated myocarditis. To test this possibility we used Met-RANTES, a N-terminally modified human RANTES that inhibits agonist activity at CCR1 and CCR5[41], to modulate the establishment of T. cruzi-elicited acute myocarditis. Our results showed that Met-RANTES treatment increased the survival of T. cruzi-infected animals when compared to saline treatment. Moreover, Met-RANTES treatment significantly decreased the inflammatory infiltrates due to CD4 and CD8 T cells, but decreases or does not interfere, depending on the therapeutic scheme used, with the heart parasitism [42].

These results indicate that the massive influx of CC chemokine receptors-bearing inflammatory cells into the heart tissue is not crucial for cell-mediated anti-T. cruzi immunity, however it seems to be critical for T. cruzi-elicited immunopathology. Thus, the beneficial role of Met-RANTES may relay on the reestablishment of balanced inflammation, however further investigation are required to unravel the beneficial effector mechanisms of Met-RANTES. Anyhow, the inhibition of CC chemokine receptors might become an attractive therapeutic strategy for further evaluation during T. cruzi infection.

Thus, further studies may provide additional insights into the mechanisms by which adhesion molecules, chemokines and chemokine receptors contribute to the establishment and regulation of the immune response in the inflamed heart during T. cruzi infection and may unravel novel therapeutic strategies aimed at limiting the inflammatory damage to cardiomyocytes, targeting integrin-mediated adhesion and chemokine-driven recruitment of leukocytes besides the specific anti-parasite drugs (Figure 1).
Figure 1: Leukocyte migration from the circulation into target tissues is a multi-step process. The first step involves transient selectin-mediated binding (rolling). Next, integrins on leukocytes are activated by chemokines (triggering), resulting in firm adhesion between leukocytes and activated adhesion molecules-bearing endothelial cells (EC). Finally, leukocytes extravasate through the vascular wall and into the tissue in response to chemokine-driven recruitment (transmigration) [19]. During T. cruzi infection, circulating CD8+ T cells express a differential profile of adhesion molecules (LFA-1High, VLA-4High). This could account to the preferential interaction with activated EC (ICAM-1+, VCAM-1+). Also, the inflamed tissue presents pro-inflammatory cytokines (IFN-g, TNF-a) and chemokines (RANTES, MIP-1a, JE/MCP-1). These might selectively and preferentially recruit CD8+ T cells leading to the establishment of CD8-mediated myocarditis [5,6]. Novel therapeutic strategies aiming at limiting the inflammatory damage of cardiomyocytes, targeting integrin-mediated adhesion and chemokine-driven recruitment of leukocytes, besides the specific anti-T. cruzi drugs, should be evaluated.

Acknowledgements
The author is deeply in debt to the MSc and PhD students and collaborators that contributed to the work discussed here. This work was supported by grants from PAPES-II-Fiocruz, CNPq, FAPERJ and IOC-Fiocruz, and fellowship from CNPq (JLV).

References

  1. Tarleton RL Parasite persistence in the aetiology of Chagas' disease. Int. J. Parasitol. 2001, 31:549-553.
  2. Cunha-Neto E. "Immunopathogenic aspects of Chagas 'heart disease" or Understanding the pathogesis of Chagas' disease cardiomyopathy towards the end of the millennium". 2001. 1st virtual congress of Cardiology. http://www.fac.org.ar/cvirtual/cvirteng/cienteng/eceng/ecc4501i/icunha.htm.
  3. Silva AA, Roffê E, Marino APMP, Santos PVA, Quirico-Santos T, Paiva CN, Lannes-Vieira J. Chagas' disease encephalitis: intense CD8+ lymphocytic infiltrates is restricted to the acute phase, but is not related to the presence of Trypanosoma cruzi antigens, Clin. Immunol. 1999, 92:56-66.
  4. Michailowsky V, Silva NM, Rocha CD, Vieira LQ, Lannes-Vieira J, Gazzinelli RT. Pivotal role of interleukin-12 and interferon-axis in controlling tissue parasitism and inflammation in the heart and central nervous system during Trypanosoma cruzi infection. Am. J. Pathol. 2001, 159:1723-1733.
  5. Talvani A, Ribeiro CS, Aliberti JCS, Michailowsky V, Santos PVA, Murta SMF, Romanha AJ, Almeida IC, Farber J, Lannes-Vieira J, Silva JS, Gazzineli RT. Kinetics of cytokine gene expression in experimental chagasic cardiomyopathy: tissue parasitism and endogenous IFN-g as important determinants of chemokine mRNA expression during infection with Trypanosoma cruzi. Microbes and Infection. 2000, 2:1-16.
  6. dos Santos Paula VA, Roffê E, Santiago HC, Torres RA, Marino APMP, Paiva CN, Silva AA, Gazzinelli RT, Lannes-Vieira J. Prevalence of CD8+a T cells in Trypanosoma cruzi-elicited myocarditis is associated with acquisition of CD62LLowLFA-1HighVLA-4High activation phenotype and expression of IFN-g-inducible adhesion and chemoattractant molecules. Microbes and Infection. 2001, 3:1-14.
  7. Shimizu Y., Shaw S., Lymphocyte interactions with extracellular matrix, FASEB J. 5 (1991) 2292-2299.
  8. Nathan C, Sporn M. Cytokines in context, J. Cell. Biol. 1991, 113:981-986.
  9. Gilat D., Cahalon L, Hershkoviz R, Lider O. Interplay of T cells and cytokines in the context of enzymatically modified extracellular matrix. Immunol. Today. 1996, 17:16-20.
  10. Del Pozo M.A., Sánchez-Mateos P., Nicto M., Sánchez-Madrid F., Chemokines regulate cellular polarization and adhesion receptor distribution during lymphocytes interaction with endothelium and extracellular matrix. Involvement of cAMP signalling pathway, J. Cell Biol. 141 (1995) 495-508.
  11. Sallusto F, Mackay CR, Lanzavechia A. The role of chemokine receptors in primary, effector, and memory immune responses. Annu. Rev. Immunol. 2000, 18: 593-620.
  12. Gerard C, Rollins BJ. chemokines and disease. Nature Immunology 2001, 2:108-115.
  13. Moser B, Loestscher P. Lymphocyte traffic control by chemokines. Nat. Immunol. 2001, 2:123-128.
  14. D'avila Reis D, Jones EM, Tostes Jr S, Lopes ER, Gazzinelli G, Colley DG, Mc Curley TL. Characterization of inflammatory infiltrates in chronic chagasic myocardial lesions: presence of tumor necrosis factor-a+ cells and dominance of granzyme A+, CD8+ lymphocytes. Am. J. Trop. Med. Hyg. 1993, 48:637-644.
  15. Higuchi ML, Gutierrez PS, Aiello VD, Palomino S, Bocchi E, Kalil J, Bellotti G, Pileggi F. Immunohistochemical characterization of infiltrating cells in human chronic chagasic myocarditis: comparison with myocardial rejection process, Virchows Archiv. A. Pathol. Anat. 1993, 423:157-160.
  16. Higuchi ML, Reis MM, Aiello VD, Benvenuti LA, Gutierrez PS, Bellotti G, Pileggi F. Association of an increase in CD8+ T cells with the presence of Trypanosoma cruzi antigens in chronic, human chagasic myocarditis, Am. J. Trop. Med. Hyg. 1997, 56:485-489.
  17. Reis MM, Higuchi ML, Benvenuti LA, Aiello VD, Gutierrez PS, Bellotti G, Pileggi F. An in situ quantitative immunohistochemical study of cytokines and IL-2R+ in chronic human chagasic myocarditis: correlation with the presence of myocardial Trypanosoma cruzi antigens. Clin. Immunol. Immunopath. 1997, 83: 165-172.
  18. Sprent J, Thougn DF, Sun S. Factors controlling the turnover of T memory cells. Immunol. Ver. 1997, 156: 79-85.
  19. Springer TA, Traffic signals on endothelium for lymphocyte recirculation and leukocyte migration, Annu. Rev. Physiol. 1995, 57:827-872.
  20. Laucella SA, Riarte A, prado N, Zapata J, Segura EL. a4 integrins and sialyl Lewis x modulation in chronic Chagas disease: further evidence of persistent immune activation. Scand. J. Immunol. 2001, 53:514-519.
  21. Andrade SG, Grimaud JA, Stocker-Guerret S. Sequential changes of the connective matrix components of the myocardium (fibronectin and laminin) and evolution of the cardiac fibrosis in mice infected with Trypanosoma cruzi. Am. J. Trop. Med. Hyg. 1989, 40: 252-260.
  22. Silu-Hännien M, Salmi A, Salonen R. Interferon-b downregulates expression of VLA-4 antigen and antagonizes interferon-g-induced expression of HLA-DQ on human peripheral blood monocytes. J. Neuroimmunol. 1995, 60:99-106.
  23. Yusuf-Makagiansar H, Anderson ME, Yakovleva TV, Murray JS, Siahaan TJ. Inhibition of LFA-1/ICAM-1 and VLA-4/VCAM-1 as a therapeutic approach to inflammation and autoimmune diseases. Med Res Rev. 2002, 22:146-67.
  24. Roffê E, Silva AA, Marino APMP, dos Santos PVA, Lannes-Vieira J.VLA-4/VCAM-1-mediated interactions play a pivotal role in the establishment of meningoencephalitis during Trypanosoma cruzi infection: in vitro and in vivo evidences. Submitted.
  25. Cook DN, Smithies O, Strieter RM, Frelinger JA, Serody JS. CD8+ T cells are a biologically relevant source of macrophage inflammatory protein-1a in vivo, J. Immunol. 1999, 162: 5423-5428.
  26. Taub DD, Conlon K, Lloyd AR, Oppenheim JJ, Kelvin DJ. Preferential migration of activated CD4+ and CD8+ T cells is response to MIP-1a and MIP-1ß. Science. 1993, 260:355-358.
  27. Brener Z, Gazzinelli RT. Immunological control of Trypanosoma cruzi infection and pathogenesis of Chagas' disease. Int. Arch. Allergy Immunol. 1997, 114:103-110.
  28. Abrahamsohn IA. Cytokines in innate and acquired immunity to Trypanosoma cruzi infection. Braz. J. Med. Biol. Res. 1998, 31:17-121.
  29. Powell MR, Morgan J, Guarner J, Cooley DG. Cytokine mRNA levels in the hearts of inbred mice that develop different degrees of cardiomyopathy during infection with Trypanosoma cruzi. Parasite Immunol. 1998, 20:463-471.
  30. Rocha A, DE Meneses AC, da Silva AM, Ferreira MS, Nishiosa SA, Burgarelli MK, Almeida E, Turcat Jr G, Metze K, Lopes ER. Pathology of patients with Chagas'disease and acquired immunodeficiency syndrome. Am. J. Trop Med Hyg 1994, 50:261-268.
  31. Tarleton R, Sun J, Zhang L, Postan M. Deplation of T-cell populations results in exarcebation of myocarditis and parasitism in experimental Chagas'disease. Infect Immun 1994, 62:1820-1829.;
  32. Tarleton RL. Depletion of CD8+ cells increases susceptibility and reverses vaccine-induced immunity in mice infected with Trypanosoma cruzi. J. Immunol 1990, 15:717-724.
  33. Villalta F, Zhang Y, Bibb KE, Kappes JC e Lima MF. The cysteine-cysteine family of chemokines RANTES, MIP-1a, and MIP-1ß induce trypanocidal activity in human macrophages via nitric oxide. Infect. Immun.. 1998; 66 (10): 4690-4695.
  34. Aliberti J.C., Machado F.S., Souto J.T., Campanelli A.P., Teixeira M.M., Gazzinelli R.T. Silva J.S., Beta-chemokines enhance parasite uptake and promote nitric oxide-dependent microbiostatic activity in murine inflammatory macrophages infected with Trypanosoma cruzi, Infect. Immun. 1999, 67:4819-4826.
  35. Machado FS, Martins GA, Aliberti JCS, Mestriner FLAC, Cunha FQ e Silva JS. Trypanosoma cruzi-infected cardiomyocytes produce chemokines and cytokines that trigger potent nitric oxide-dependent trypanocidal activity. Circulation. 2000; 102: 3003-3008.
  36. Aliberti JCS, Souto JT, Marino APMP, Lannes-Vieira J, Teixeira MM, Farber J, Gazzinelli RT e Silva JS. Modulation of chemokine production and inflammatory responses in interferon-g and-tumor necrosis factor-R1-deficient mice during Trypanosoma cruzi infection. Am. J. Pathol. 2001,158: 1433-1440.
  37. Proudfoot AE . Chemokine receptors: multifaceted therapeutic targets. Nature Review Immunol. 2002, 2:106-115.
  38. Talvani A, Rocha MOC, Klein A, Gomes I, Falcão PL, Teixeira MM. Chemokine receptors expression by PBMC in human chagasic cardiomyophaty. Revista da Sociedade Brasileira de Medicina Tropical. 2001, 34(supl II:102.
  39. Calzada JE, Nieto A, Beraun Y, Martin J. Chemokine receptor CCR5 polymorphisms and Chagas' disease cardiomyopathy. Tissue Antigens. 2001 Sep;58(3):154-8.
  40. Teixeira MM, Gazzinelli RT, Silva JS. Chemokines, inflammation and Trypanosoma cruzi infection. Trends in Immunology. 2002, 18:262-265.
  41. Proudfoot AE, Buser R, Borlat F, Alouani S, Solerr D, Offord RE, Schroder JM, Power CA, Wells TN. Amino-terminally modified RANTES analogues demonstrate differential effects on RANTES receptors. J. Biol. Chem. 1999, 274:32478-32485.
  42. Marino APMP, Teixeira MM, Pinto LMO, Lannes-Vieira J. RANTES antagonist (Met-RANTES) controls acute T. cruzi-elicited myocarditis. Submitted.

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