title: S-nitrosoglutathione (GSNO) is cytotoxic to intracellular amastigotes and promotes healing of topically treated Leishmania major or Leishmania braziliensis skin lesions.
abstract: OBJECTIVE
  This study was designed to verify the cytotoxic activity of S-nitrosoglutathione (GSNO) against intracellular Leishmania amastigotes and to test its efficacy as a topical treatment of localized cutaneous leishmaniasis (LCL) in Leishmania major- or Leishmania braziliensis-infected mice.
  
  
  METHODS
  Cytotoxic activity of GSNO was verified in L. major-infected THP-1 macrophages. S-nitrosated proteins were detected by immunofluorescence. Topical treatment was done by daily application of a solution of GSNO in PBS to the skin ulcer of Leishmania-infected mice. BALB/c and interferon-γ-knockout (IFN-γ-KO) C57BL/6 mice were infected with L. major and L. braziliensis, respectively. Ulcer size was measured weekly and the parasite loads were determined in the lesion and lymph nodes. Controls received PBS topically or amphotericin B (AMB) intravenously.
  
  
  RESULTS
  The number of intracellular L. major amastigotes was markedly reduced in GSNO-treated cultures; in these, staining for S-nitrosated proteins was present in the cytoplasm and colocalized with intracellular amastigotes. Topical treatment with GSNO of L. major ulcers in BALB/c mice suppressed lesion growth, reduced the parasite load and induced healing comparable to the effect of intravenously administered AMB. Topical GSNO treatment was also efficient at suppressing lesion growth in IFN-γ-KO mice infected with L. braziliensis.
  
  
  CONCLUSIONS
  GSNO is cytotoxic to intracellular L. major amastigotes in vitro and had a healing effect on LCL caused by L. major and L. braziliensis in mice. These positive results on the topical therapeutic effect of GSNO in mouse leishmaniasis infections provide the experimental basis for a possible future trial in the treatment of human LCL.
authors.affiliation: Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, USP, 05508-900 São Paulo, SP, Brazil.
authors.forename: Inez Silva Fernandes
authors.initials: IS
authors.lastname: Costa
authors.forename: Gabriela Freitas Pereira
authors.initials: GF
authors.lastname: de Souza
authors.forename: Marcelo Ganzarolli
authors.initials: MG
authors.lastname: de Oliveira
authors.forename: Ises de Almeida
authors.initials: Ide A
authors.lastname: Abrahamsohn
mesh_terms: D000287:Administration, Topical; D000818:Animals; D000977:Antiparasitic Agents / Q000008:administration & dosage*; D004195:Disease Models, Animal; D005260:Female; D007892:Leishmania braziliensis / Q000187:drug effects*; D018320:Leishmania major / Q000187:drug effects*; D016773:Leishmaniasis, Cutaneous / Q000188:drug therapy* / Q000469:parasitology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D059208:Parasite Load; D026422:S-Nitrosoglutathione / Q000008:administration & dosage*; D012867:Skin / Q000469:parasitology / Q000473:pathology; D016896:Treatment Outcome; D014456:Ulcer / Q000469:parasitology / Q000473:pathology
chemical_list: D000977:Antiparasitic Agents; D026422:S-Nitrosoglutathione
keywords: S-nitrosothiols; localized cutaneous leishmaniasis-LCL; nitric oxide donor molecules; therapy