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Specific uptake of tumor necrosis factor-alpha is involved in growth control of Trypanosoma brucei.

Magez S, Geuskens M, Beschin A, del Favero H, Verschueren H, Lucas R, Pays E, de Baetselier P - J. Cell Biol. (1997)

Bottom Line: The specific uptake of the cytokine by the parasite results in a developmentally regulated loss of osmoregulatory capacity.Anti-TNF-alpha treatment of T. brucei-infected mice reveals a dramatic increase in parasitaemia in the blood circulation, the spleen, the lymph nodes, and the peritoneal cavity.These data suggest that in the mammalian host, TNF-alpha is involved in the growth control of T. brucei.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Cellular Immunology, Flanders Interuniversity Institute for Biotechnology, Vrije Universiteit Brussel, Belgium.

ABSTRACT
Trypanosoma brucei is lysed by tumor necrosis factor-alpha (TNF-alpha) in a dose-dependent way, involving specific binding of the cytokine to a trypanosomal glycoprotein present in the flagellar pocket of the parasite. TNF-alpha-gold particles are endocytosed via coated pits and vesicles and are directed towards lysosome-like digestive organelles. The specific uptake of the cytokine by the parasite results in a developmentally regulated loss of osmoregulatory capacity. TNF-alpha specific lysis is prevented when lysis assays are performed at a temperature <26 degrees C, despite uptake of the cytokine. Inhibition of lysis is also observed when a lysosomotropic agent is added during the first 2 h of incubation. Both monomorphic and pleomorphic trypanosomes are lysed but only when isolated during the peak of parasitaemia. Lysis is not observed with early infection stage parasites or procyclic (insect-specific) forms. Anti-TNF-alpha treatment of T. brucei-infected mice reveals a dramatic increase in parasitaemia in the blood circulation, the spleen, the lymph nodes, and the peritoneal cavity. These data suggest that in the mammalian host, TNF-alpha is involved in the growth control of T. brucei.

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Transmission electron microscopy analysis of intracellular uptake of TNF-α–gold particles and lysis of bloodstream forms of  T. brucei, isolated at the early stage and the peak of the parasitaemia. Cells were incubated with TNF-α–gold particles at a concentration  of ∼105 U/ml. (a) Peak stage parasites were incubated at 30°C with TNF-α–gold particles for a total period of 4 h as described in Materials and Methods. TNF-α–gold particles are observed in a vacuole of an apparent intact parasite (inset, arrowhead), while other cells are  completely lysed. A large disruption in the membrane of the TNF-α–gold containing vesicle is indicated in the inset (arrow). m, mitochondria. (b) Peak stage parasites were incubated at 17°C with TNF-α–gold particles for a total period of 4 h. TNF-α–gold particles are  observed in two vacuoles (center inset, arrowhead). No lysed cells were observed under these experimental conditions. (c) Early-stage T.  brucei bloodstream forms were incubated with TNF-α–gold particles for a total period of 4 h. TNF-α–gold particles are observed in a  vacuole surrounding a cytoplasmic area and in a smaller vesicle (bottom inset, arrowheads). No lysis was observed under these experimental conditions. Bars: (a–c) 1 μm, (inset) 0.1 μm.
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Figure 8: Transmission electron microscopy analysis of intracellular uptake of TNF-α–gold particles and lysis of bloodstream forms of T. brucei, isolated at the early stage and the peak of the parasitaemia. Cells were incubated with TNF-α–gold particles at a concentration of ∼105 U/ml. (a) Peak stage parasites were incubated at 30°C with TNF-α–gold particles for a total period of 4 h as described in Materials and Methods. TNF-α–gold particles are observed in a vacuole of an apparent intact parasite (inset, arrowhead), while other cells are completely lysed. A large disruption in the membrane of the TNF-α–gold containing vesicle is indicated in the inset (arrow). m, mitochondria. (b) Peak stage parasites were incubated at 17°C with TNF-α–gold particles for a total period of 4 h. TNF-α–gold particles are observed in two vacuoles (center inset, arrowhead). No lysed cells were observed under these experimental conditions. (c) Early-stage T. brucei bloodstream forms were incubated with TNF-α–gold particles for a total period of 4 h. TNF-α–gold particles are observed in a vacuole surrounding a cytoplasmic area and in a smaller vesicle (bottom inset, arrowheads). No lysis was observed under these experimental conditions. Bars: (a–c) 1 μm, (inset) 0.1 μm.

Mentions: Similar experiments were performed with TNF-α–gold particles, i.e., trypanosomes were incubated for 1 h with TNF-α–gold at 17° or 30°C. Subsequently, the samples were washed and reincubated during 4 h at the respective temperatures. TEM analysis shown in Fig. 8 indicates that parasites preincubated with TNF-α–gold particles during 1 h at 30°C, started lysing after a total incubation time of 4 h at this temperature. (Fig. 8 a). In contrast, parasites preincubated at 17°C with TNF-α–gold particles, and kept at this temperature for another 3 h, did not exhibit any sign of lysis, although TNF-α–gold complexes were clearly internalized (Fig. 8 b). At 30°C, lysis was found to be preceded by swelling of the vesicles containing TNF-α–gold particles and of the mitochondria. Often, vesicles containing TNF-α–gold particles exhibit large disruptions of their membranes (Fig. 8 a, arrow). Such events preceded prompt lysis. At 17°C, gold conjugates were found to be endocytosed, yet swelling of TNF-α–collecting organelles or lysis of cells was not recorded (Fig. 8 b).


Specific uptake of tumor necrosis factor-alpha is involved in growth control of Trypanosoma brucei.

Magez S, Geuskens M, Beschin A, del Favero H, Verschueren H, Lucas R, Pays E, de Baetselier P - J. Cell Biol. (1997)

Transmission electron microscopy analysis of intracellular uptake of TNF-α–gold particles and lysis of bloodstream forms of  T. brucei, isolated at the early stage and the peak of the parasitaemia. Cells were incubated with TNF-α–gold particles at a concentration  of ∼105 U/ml. (a) Peak stage parasites were incubated at 30°C with TNF-α–gold particles for a total period of 4 h as described in Materials and Methods. TNF-α–gold particles are observed in a vacuole of an apparent intact parasite (inset, arrowhead), while other cells are  completely lysed. A large disruption in the membrane of the TNF-α–gold containing vesicle is indicated in the inset (arrow). m, mitochondria. (b) Peak stage parasites were incubated at 17°C with TNF-α–gold particles for a total period of 4 h. TNF-α–gold particles are  observed in two vacuoles (center inset, arrowhead). No lysed cells were observed under these experimental conditions. (c) Early-stage T.  brucei bloodstream forms were incubated with TNF-α–gold particles for a total period of 4 h. TNF-α–gold particles are observed in a  vacuole surrounding a cytoplasmic area and in a smaller vesicle (bottom inset, arrowheads). No lysis was observed under these experimental conditions. Bars: (a–c) 1 μm, (inset) 0.1 μm.
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Figure 8: Transmission electron microscopy analysis of intracellular uptake of TNF-α–gold particles and lysis of bloodstream forms of T. brucei, isolated at the early stage and the peak of the parasitaemia. Cells were incubated with TNF-α–gold particles at a concentration of ∼105 U/ml. (a) Peak stage parasites were incubated at 30°C with TNF-α–gold particles for a total period of 4 h as described in Materials and Methods. TNF-α–gold particles are observed in a vacuole of an apparent intact parasite (inset, arrowhead), while other cells are completely lysed. A large disruption in the membrane of the TNF-α–gold containing vesicle is indicated in the inset (arrow). m, mitochondria. (b) Peak stage parasites were incubated at 17°C with TNF-α–gold particles for a total period of 4 h. TNF-α–gold particles are observed in two vacuoles (center inset, arrowhead). No lysed cells were observed under these experimental conditions. (c) Early-stage T. brucei bloodstream forms were incubated with TNF-α–gold particles for a total period of 4 h. TNF-α–gold particles are observed in a vacuole surrounding a cytoplasmic area and in a smaller vesicle (bottom inset, arrowheads). No lysis was observed under these experimental conditions. Bars: (a–c) 1 μm, (inset) 0.1 μm.
Mentions: Similar experiments were performed with TNF-α–gold particles, i.e., trypanosomes were incubated for 1 h with TNF-α–gold at 17° or 30°C. Subsequently, the samples were washed and reincubated during 4 h at the respective temperatures. TEM analysis shown in Fig. 8 indicates that parasites preincubated with TNF-α–gold particles during 1 h at 30°C, started lysing after a total incubation time of 4 h at this temperature. (Fig. 8 a). In contrast, parasites preincubated at 17°C with TNF-α–gold particles, and kept at this temperature for another 3 h, did not exhibit any sign of lysis, although TNF-α–gold complexes were clearly internalized (Fig. 8 b). At 30°C, lysis was found to be preceded by swelling of the vesicles containing TNF-α–gold particles and of the mitochondria. Often, vesicles containing TNF-α–gold particles exhibit large disruptions of their membranes (Fig. 8 a, arrow). Such events preceded prompt lysis. At 17°C, gold conjugates were found to be endocytosed, yet swelling of TNF-α–collecting organelles or lysis of cells was not recorded (Fig. 8 b).

Bottom Line: The specific uptake of the cytokine by the parasite results in a developmentally regulated loss of osmoregulatory capacity.Anti-TNF-alpha treatment of T. brucei-infected mice reveals a dramatic increase in parasitaemia in the blood circulation, the spleen, the lymph nodes, and the peritoneal cavity.These data suggest that in the mammalian host, TNF-alpha is involved in the growth control of T. brucei.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Cellular Immunology, Flanders Interuniversity Institute for Biotechnology, Vrije Universiteit Brussel, Belgium.

ABSTRACT
Trypanosoma brucei is lysed by tumor necrosis factor-alpha (TNF-alpha) in a dose-dependent way, involving specific binding of the cytokine to a trypanosomal glycoprotein present in the flagellar pocket of the parasite. TNF-alpha-gold particles are endocytosed via coated pits and vesicles and are directed towards lysosome-like digestive organelles. The specific uptake of the cytokine by the parasite results in a developmentally regulated loss of osmoregulatory capacity. TNF-alpha specific lysis is prevented when lysis assays are performed at a temperature <26 degrees C, despite uptake of the cytokine. Inhibition of lysis is also observed when a lysosomotropic agent is added during the first 2 h of incubation. Both monomorphic and pleomorphic trypanosomes are lysed but only when isolated during the peak of parasitaemia. Lysis is not observed with early infection stage parasites or procyclic (insect-specific) forms. Anti-TNF-alpha treatment of T. brucei-infected mice reveals a dramatic increase in parasitaemia in the blood circulation, the spleen, the lymph nodes, and the peritoneal cavity. These data suggest that in the mammalian host, TNF-alpha is involved in the growth control of T. brucei.

Show MeSH
Related in: MedlinePlus