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Schwann cells as putative safe host cells for Leishmania amazonensis

2009; Elsevier BV; Volume: 13; Issue: 5 Linguagem: Inglês

10.1016/j.ijid.2008.11.008

1878-3511

Wagner Baetas‐da‐Cruz, Suzana Côrte‐Real, Leny A. Cavalcante,

Blood Coagulation and Thrombosis Mechanisms

A hallmark of Leishmania infection is the invasion of tissue macrophages by the parasite as an essential step for the establishment of parasitism. In fact, macrophages are considered the most important host cell for Leishmania parasites,1Naderer T. McConville M.J. The Leishmania-macrophage interaction: a metabolic perspective.Cell Microbiol. 2008; 10: 301-308Crossref PubMed Scopus (140) Google Scholar although several other cell types are able to endocytose Leishmania in vitro or in vivo.2Hervás Rodríguez J. Mozos E. Méndez A. Pérez J. Gómez-Villamandos J.C. Leishmania infection of canine skin fibroblasts in vivo.Vet Pathol. 1996; 33: 469-473Crossref PubMed Scopus (27) Google Scholar, 3Bogdan C. Donhauser N. Döring R. Röllinghoff M. Diefenbach A. Rittig M.G. Fibroblasts as host cells in latent Leishmaniasis.J Exp Med. 2000; 191: 2121-2130Crossref PubMed Scopus (166) Google Scholar, 4Hespanhol R.C. de Nazaré C. Soeiro M. Meuser M.B. de Nazareth S.L. Meirelles M. Côrte-Real S. The expression of mannose receptors in skin fibroblast and their involvement in Leishmania (L.) amazonensis invasion.J Histochem Cytochem. 2005; 53: 35-44Crossref PubMed Google Scholar Previous data published by our and other groups support the notion that Schwann cells (SCs) act as a putative host cell for Leishmania infection.5Satti M.B. el-Hassan A.M. al-Gindan Y. Osman M.A. al-Sohaibani M.O. Peripheral neural involvement in cutaneous leishmaniasis. A pathologic study of human and experimental animal lesions.Int J Dermatol. 1989; 28: 243-247Crossref PubMed Scopus (30) Google Scholar, 6Baetas-Da-Cruz W. Castro P. Guimarães E.V. Koatz V.L. Corte-Real S. Cavalcante L.A. Increase in nuclear translocation of nuclear transcription factor-kappaB following infection of a human Schwann cell line with Leishmania amazonensis.Br J Dermatol. 2008; 158: 631-633Crossref PubMed Scopus (4) Google Scholar In this context, we hypothesized that SCs, abundant in highly innervated skin, might form a less hostile environment for Leishmania than macrophages and, thus, enable the persistence of the parasite. We evaluated the infection of a human SC line (ST88-14) by promastigotes of Leishmania amazonensis (LA) and also the potential effect of infection on nitric oxide (NO) production by these cells. The ST88-14 SC line represents a good model for our study because these cells express some phenotypical markers of normal SCs.7Oliveira R.B. Ochoa M.T. Sieling P.A. Rea T.H. Rambukkana A. Sarno E.N. Modlin R.L. Expression of Toll-like receptor 2 on human Schwann cells: a mechanism of nerve damage in leprosy.Infect Immun. 2003; 71: 1427-1433Crossref PubMed Scopus (132) Google Scholar, 8Ryan J.J. Klein K.A. Neuberger T.J. Leftwich J.A. Westin E.H. Kauma S. et al.Role for the stem cell factor/KIT complex in Schwann cell neoplasia and mast cell proliferation associated with neurofibromatosis.J Neurosci Res. 1994; 37: 415-432Crossref PubMed Scopus (81) Google Scholar ST88-14 cells (generously donated by Jonathan Fletcher, Dana Farber Cancer Institute, Boston, USA) were isolated from a patient with neurofibromatosis type 1. LA (MHOM/BR/77/LTB0016), isolated from a human case of cutaneous leishmaniasis, was kindly supplied by Dr. Gabriel Grimaldi Jr. (Fundação Oswaldo Cruz, Rio de Janeiro, Brazil). An in vitro protocol for infection of ST88-14 by LA promastigote forms was performed at skin temperature (34 °C), as previously described.6Baetas-Da-Cruz W. Castro P. Guimarães E.V. Koatz V.L. Corte-Real S. Cavalcante L.A. Increase in nuclear translocation of nuclear transcription factor-kappaB following infection of a human Schwann cell line with Leishmania amazonensis.Br J Dermatol. 2008; 158: 631-633Crossref PubMed Scopus (4) Google Scholar The percentage of ST88-14 cells containing internalized parasites was determined after Giemsa staining and examination in bright-field optics. In order to investigate NO production, culture supernatants were analyzed for their content of nitrite using the Griess reaction.9Stenger S. Thüring H. Röllinghoff M. Bogdan C. Tissue expression of inducible nitric oxide synthase is closely associated with resistance to Leishmania major.J Exp Med. 1994; 180: 783-793Crossref PubMed Scopus (266) Google Scholar Highly purified bovine serum albumin (BSA) at 2% concentration was tested in place of fetal bovine serum (FBS) during the NO measurement and infection protocols. The supernatants from infected and non-infected ST88-14 cells were collected at different times and afterwards mixed with 100 μl of the Griess reagent. After 10 min incubation at room temperature, the optical density was measured in a microtiter plate reader (Flow, Meckenheim, Germany) at 546 nm against a medium without phenol red as blank. A sodium nitrite standard curve (0–100 μM) was generated in parallel. As interferon-γ (IFN-γ) plays a major role in NO production, we investigated whether treatment with recombinant IFN-γ (rIFN-γ) could alter the base levels of NO in ST88-14 cells both infected and not infected by LA. Treatment of the cultures with rIFN-γ (100 U/ml) resulted in a substantial increase in NO release by ST88-14 cells after 48 hr of stimulation at 37 °C. On the other hand, this increase was not observed in cultures previously infected by LA at 34 °C for 24 hr and maintained for an additional period for 48 hr at 37 °C (Figure 1). Neither control nor infected cells augmented their (low) production of NO by incubation with lipopolysaccharide (LPS). No synergic action was observed after LPS combination with rIFN-γ not shown). Our results show that rINF-γ treatment drives SCs into a potentially lethal function, increasing NO levels, which in turn can be suppressed by LA infection. These data contrast markedly with previous work carried out in a murine macrophage cell line, in which it was observed that addition of rIFN-γ restores NO levels in cultures that were infected with LA before LPS stimulation.10Balestieri F.M. Queiroz A.R. Scavone C. Costa V.M. Barral-Netto M. Abrahamsohn Ide A. Leishmania (L.) amazonensis-induced inhibition of nitric oxide synthesis in host macrophages.Microbes Infect. 2002; 4: 23-29Crossref PubMed Scopus (69) Google Scholar Thus, we suggest that, in contrast to macrophages, SCs might serve as safe targets for the parasite, providing a more stable environment for evasion of the immune system. Collectively, the preliminary results presented here, as well as our previous work,6Baetas-Da-Cruz W. Castro P. Guimarães E.V. Koatz V.L. Corte-Real S. Cavalcante L.A. Increase in nuclear translocation of nuclear transcription factor-kappaB following infection of a human Schwann cell line with Leishmania amazonensis.Br J Dermatol. 2008; 158: 631-633Crossref PubMed Scopus (4) Google Scholar identify SCs as a prospectively important host cell for Leishmania. SCs might exert immunoregulatory functions determining susceptibility or resistance to this intracellular parasite. Financial support for this work was provided by the Brazilian Council for Science and Technology (CNPq) and the Rio de Janeiro State Foundation for Research Support (FAPERJ). Conflict of interest: No conflict of interest to declare. The authors have no commercial association in any of the products, drugs or instruments described in the article. This study was approved by our local ethics committee.