Pregnancy enhances the innate immune response in experimental cutaneous leishmaniasis through hormone-modulated nitric oxide production

Yaneth Osorio, Diana L. Bonilla, Alex G. Peniche, Peter C. Melby, Bruno L. Travi

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


The maintenance of host defense during pregnancy may depend on heightened innate immunity. We evaluated the immune response of pregnant hamsters during early infection with Leishmania (Viannia) panamensis, a cause of American cutaneous leishmaniasis. At 7 days post-infection, pregnant animals showed a lower parasite burden compared with nonpregnant controls at the cutaneous infection site (P=0.0098) and draining lymph node (P=0.02). Resident peritoneal macrophages and neutrophils from pregnant animals had enhanced Leishmania killing capacity compared with nonpregnant controls (P=0.018 each). This enhanced resistance during pregnancy was associated with increased expression of inducible NO synthase (iNOS) mRNA in lymph node cells (P=0.02) and higher NO production by neutrophils (P=0.0001). Macrophages from nonpregnant hamsters infected with L. panamensis released high amounts of NO upon estrogen exposure (P=0.05), and addition of the iNOS inhibitor L-N6-(1-iminoethyl) lysine blocked the induction of NO production (P=0.02). Infected, nonpregnant females treated with estrogen showed a higher percentage of cells producing NO at the infection site than controls (P=0.001), which correlated with lower parasite burdens (P=0.036). Cultured macrophages or neutrophils from estrogen-treated hamsters showed significantly increased NO production and Leishmania killing compared with untreated controls. iNOS was identified as the likely source of estrogen-induced NO in primed and naïve macrophages, as increased transcription was evident by realtime PCR. Thus, the innate defense against Leishmania infection is heightened during pregnancy, at least in part as a result of estrogen-mediated up-regulation of iNOS expression and NO production.

Original languageEnglish (US)
Pages (from-to)1413-1422
Number of pages10
JournalJournal of Leukocyte Biology
Issue number6
StatePublished - Jun 1 2008
Externally publishedYes


  • Estrogen
  • Hamster
  • Leishmania

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Cell Biology


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