Influence of the Notch system in the therapeutic response of American tegumentary leishmaniasis

The evolution and therapeutic outcome of American tegumentary leishmaniasis (ATL) depend upon many factors, including the balance between Th1 and Th2 cytokines to control parasite multiplication and lesion extension. Other cytokines known for their role in inflammatory processes such as interleukin IL-17 or IL-18 as well as factors controlling keratinocyte differentiation and the inflammatory process in the skin, like the Notch system, could also be involved in the disease outcome. Notch receptors are a group of transmembrane proteins that regulate cell fate decisions during development and adulthood in many tissues, including keratinocyte differentiation and T-cell lineage commitment, depending on their activation by specific groups of ligands (Delta-like or Jagged).

To compare the in situ expression of Notch system proteins (receptors, ligands and transcriptional factors) and cytokines possibly involved in the disease outcome (IL-17, IL-18, IL-23 and transforming growth factor-β) in ATL cutaneous and mucosal lesions, according to the response to therapy with N-methyl glucamine.

Cutaneous and mucosal biopsies obtained from patients prior to therapy with N-methyl glucamine were analysed by immunohistochemistry and real-time polymerase chain reaction.

Notch receptors and Delta-like ligands were found increased in patients with ATL, particularly those with poor response to therapy or with mucosal lesions.

The increase of Notch receptors and Delta-like ligands in patients with a poor response to treatment suggests that these patients would require a more aggressive therapeutic approach or at least a more thorough and rigorous follow-up.