Trypanosome apoptotic factor mediates apoptosis in human brain vascular endothelial cells.
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.
Stiles
Jonathan K
JK
Department of Microbiology, Biochemistry and Immunology, Morehouse School of Medicine, 720 Westview Dr. S.W., Atlanta, GA 30310-1495, USA. stilesj@msm.edu
Whittaker
Joseph
J
Sarfo
Bismark Y
BY
Thompson
Winston E
WE
Powell
Michael D
MD
Bond
Vincent C
VC
D000818:Animals; D017209:Apoptosis; D001921:Brain / Q000469:parasitology / Q000473:pathology*; D001933:Brain Stem / Q000473:pathology; D053148:Caspase 3; D020169:Caspases / Q000096:biosynthesis / Q000235:genetics; D002460:Cell Line; D002531:Cerebellum / Q000473:pathology; D053938:DNA Fragmentation; D004195:Disease Models, Animal; D010450:Endopeptidases / Q000378:metabolism; D042783:Endothelial Cells / Q000473:pathology*; D006801:Humans; D020287:In Situ Nick-End Labeling; D008297:Male; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009842:Oligopeptides / Q000138:chemical synthesis / Q000494:pharmacology; D015800:Protozoan Proteins / Q000096:biosynthesis / Q000502:physiology*; D013696:Temperature; D014346:Trypanosoma brucei brucei / Q000378:metabolism / Q000472:pathogenicity*; D014353:Trypanosomiasis, African / Q000469:parasitology / Q000473:pathology*
D008562:Membrane Glycoproteins; D009842:Oligopeptides; D015800:Protozoan Proteins; C053277:procyclic acidic repetitive protein, Trypanosoma; D010450:Endopeptidases; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases