Macromolecular biosynthetic parameters and metabolic profile in different life stages of Leishmania braziliensis: Amastigotes as a functionally less active stage

PLoS One. 2017 Jul 25;12(7):e0180532. doi: 10.1371/journal.pone.0180532. eCollection 2017.

Abstract

It was recently hypothesized that Leishmania amastigotes could constitute a semi-quiescent stage characterized by low replication and reduced metabolic activity. This concept developed with Leishmania (Leishmania) mexicana and Leishmania (Leishmania) major models might explain numerous clinical and sub-clinical features of Leishmania (Viannia) braziliensis infections, like reactivation of the disease, non-response to chemotherapy or asymptomatic infections. We compared here in vitro the proliferative capability of L. (V.) braziliensis amastigotes and promastigotes, assessed the expression of key molecular parameters and performed metabolomic analysis. We found that contrary to the highly proliferative promastigotes, amastigotes (axenic and intracellular) do not show evidence of extensive proliferation. In parallel, amastigotes showed a significant decrease of (i) the kDNA mini-circle abundance, (ii) the intracellular ATP level, (iii) the ribosomal components: rRNA subunits 18S and 28S α and ribosomal proteins RPS15 and RPL19, (iv) total RNA and protein levels. An untargeted metabolomic study identified clear differences between the different life stages: in comparison to logarithmic promastigotes, axenic amastigotes showed (a) a strong decrease of 14 essential and non-essential amino acids and eight metabolites involved in polyamine synthesis, (b) extensive changes in the phospholipids composition and (c) increased levels of several endogenous and exogenous sterols. Altogether, our results show that L. (V.) braziliensis amastigotes can show a phenotype with negligible rate of proliferation, a lower capacity of biosynthesis, a reduced bio-energetic level and a strongly altered metabolism. Our results pave the way for further exploration of quiescence among amastigotes of this species.

MeSH terms

  • Adenosine Diphosphate / metabolism
  • Adenosine Triphosphate / metabolism
  • Animals
  • Biosynthetic Pathways
  • Cells, Cultured
  • Female
  • Leishmania braziliensis / growth & development*
  • Leishmania braziliensis / metabolism*
  • Leishmaniasis, Cutaneous / parasitology*
  • Metabolome*
  • Mice, Inbred BALB C
  • Protozoan Proteins / analysis
  • Protozoan Proteins / metabolism
  • RNA, Protozoan / analysis
  • RNA, Protozoan / metabolism
  • Ribosomal Proteins / analysis
  • Ribosomal Proteins / metabolism

Substances

  • Protozoan Proteins
  • RNA, Protozoan
  • Ribosomal Proteins
  • Adenosine Diphosphate
  • Adenosine Triphosphate

Grants and funding

This work was financially supported by the Belgian Directorate General for Development Cooperation-DGDC within the context of the framework agreement 3.III., project 1.13. MB was supported by the Baillet Latour Foundation; GdM and BC were supported by the Research Foundation Flanders (Grants 12Q8115N and 11O1614N, respectively). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.