Trypanosome apoptotic factor mediates apoptosis in human brain vascular endothelial cells

Mol Biochem Parasitol. 2004 Feb;133(2):229-40. doi: 10.1016/j.molbiopara.2003.10.011.

Abstract

Human African trypanosomiasis (HAT, sleeping sickness) is a devastating disease caused by infection with Trypanosoma brucei ssp. These hemoflagellates invade the central nervous system (CNS) and induce meningo-encephalitis, neuronal demyelination, blood-brain-barrier (BBB) dysfunction, peri-vascular infiltration, astrocytosis and apoptosis. The molecular basis of these manifestations is unclear. We previously reported T. brucei-induced apoptosis in cerebella and brain-stem nuclei in mice at peak parasitemia. Here, we identify and characterize a trypanosome apoptotic factor (TAF) expressed by T. brucei that mediates apoptosis in mouse-brain and human-brain vascular endothelial cells (HBVEC). Molecular, biochemical and apoptotic assays, coupled with surface enhanced laser desorption ionization (SELDI), and protein database analyses were utilized to show that TAF is a soluble, non-serum, parasite-derived, heat-labile protein that causes DNA laddering and apoptosis in HBVEC. Protein-chip assay analysis of the SELDI spectrum of infected mouse serum and procyclic culture supernatants revealed a single major peak at 8652.7 Da. Further database analysis indicated that the TAF may be a procyclin or procyclin derivative. A synthetic 27 mer peptide (ProEP2-1), corresponding to a region common to EP procyclins (EP2-1), induced apoptosis in HBVEC and in cerebella of mice similar to that induced in T. brucei-infected mice. Western blot analysis utilizing an anti-procyclin monoclonal antibody (mAb) revealed that TAF is present in infected but not uninfected brain tissue lysates. Furthermore, this mAb blocked T. brucei- and ProEP2-1-induced apoptosis in HBVEC in vitro. We conclude that T. brucei TAF or its derivative(s) play a major role in the apoptosis associated with HAT pathology.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Apoptosis*
  • Brain / parasitology
  • Brain / pathology*
  • Brain Stem / pathology
  • Caspase 3
  • Caspases / biosynthesis
  • Caspases / genetics
  • Cell Line
  • Cerebellum / pathology
  • DNA Fragmentation
  • Disease Models, Animal
  • Endopeptidases / metabolism
  • Endothelial Cells / pathology*
  • Humans
  • In Situ Nick-End Labeling
  • Male
  • Membrane Glycoproteins / biosynthesis
  • Membrane Glycoproteins / physiology*
  • Mice
  • Mice, Inbred BALB C
  • Oligopeptides / chemical synthesis
  • Oligopeptides / pharmacology
  • Protozoan Proteins / biosynthesis
  • Protozoan Proteins / physiology*
  • Temperature
  • Trypanosoma brucei brucei / metabolism
  • Trypanosoma brucei brucei / pathogenicity*
  • Trypanosomiasis, African / parasitology
  • Trypanosomiasis, African / pathology*

Substances

  • Membrane Glycoproteins
  • Oligopeptides
  • Protozoan Proteins
  • procyclic acidic repetitive protein, Trypanosoma
  • Endopeptidases
  • CASP3 protein, human
  • Casp3 protein, mouse
  • Caspase 3
  • Caspases