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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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Morphological  analysis by TEM and FSC of  TNF-α–induced trypanolysis  in function of time (a, 1 h, b,  3 h, c, 4 h, d, 5 h). Purified  trypanosomes were incubated for various periods of  time in PSG (pH 8.0) in the  presence or absence of 105 U/ ml TNF-α. (A) TEM analysis  of TNF-α–treated T. brucei  parasites. Swelling of organelles and lysis of parasites was recorded from 4 h  of incubation onwards (Ac).  (B) TEM analysis of nontreated T. brucei parasites.  No lysis was observed. (C)  FSC of TNF-α–treated T.  brucei parasites. A major  shift to the left of the FSC  spectrum was observed from  4 h of incubation onwards  (Cc). Bar, 1 μm.
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Figure 2: Morphological analysis by TEM and FSC of TNF-α–induced trypanolysis in function of time (a, 1 h, b, 3 h, c, 4 h, d, 5 h). Purified trypanosomes were incubated for various periods of time in PSG (pH 8.0) in the presence or absence of 105 U/ ml TNF-α. (A) TEM analysis of TNF-α–treated T. brucei parasites. Swelling of organelles and lysis of parasites was recorded from 4 h of incubation onwards (Ac). (B) TEM analysis of nontreated T. brucei parasites. No lysis was observed. (C) FSC of TNF-α–treated T. brucei parasites. A major shift to the left of the FSC spectrum was observed from 4 h of incubation onwards (Cc). Bar, 1 μm.

Mentions: To study the morphological alterations that may occur during trypanolysis, TNF-α–treated parasites were analyzed by TEM and flow cytometry (FSC analysis). Concordant with the lysis experiments, TNF-α–induced morphological alterations occurred suddenly and progressed very fast (Fig. 2). Indeed, after 1 to 3 h of incubation with TNF-α, TEM analysis of the parasites revealed no major morphological changes (Fig. 2, Aa and Ab) and only a minor shift in FSC signals (∼5%) was recorded by flow cytometric analysis after 3 h of incubation (Fig. 2 Cb). At this time point, light microscopy analysis only indicated that a minor population became nonmotile. After 4 h, an important part of the trypanosome population analyzed in TEM manifested gross morphological alterations in the presence of TNF-α. As shown in Fig. 2 Ac, normal cells were observed in the vicinity of cells with swollen organelles and ruptured plasma membranes, reminiscent of an osmotic shock treatment. Concomitantly, the FSC signal of a major part of the parasites shifted to the left (Fig. 2 Cc) and indicated a trypanolysis of ∼40%. After 5 h of incubation, TEM analysis showed a far progressed lysis, although some completely intact cells were still found to be present (Fig. 2 Ad). FSC analysis indicated a trypanolysis in the range of 85% (Fig. 2 Cd). Control parasites that were incubated in the absence of TNF-α and analyzed in TEM showed no changes in morphology during the course of this experiment (Fig. 2 B, a–d). During trypanolysis experiments, we never recorded a TNF-α specific lysis >85%, not even when incubations were performed for periods up to 8 h. This observation indicates that within an apparently morphologically homogenous population of monomorphic trypanosomes, there is a heterogeneity with regard to TNF-α sensitivity.


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)

Morphological  analysis by TEM and FSC of  TNF-α–induced trypanolysis  in function of time (a, 1 h, b,  3 h, c, 4 h, d, 5 h). Purified  trypanosomes were incubated for various periods of  time in PSG (pH 8.0) in the  presence or absence of 105 U/ ml TNF-α. (A) TEM analysis  of TNF-α–treated T. brucei  parasites. Swelling of organelles and lysis of parasites was recorded from 4 h  of incubation onwards (Ac).  (B) TEM analysis of nontreated T. brucei parasites.  No lysis was observed. (C)  FSC of TNF-α–treated T.  brucei parasites. A major  shift to the left of the FSC  spectrum was observed from  4 h of incubation onwards  (Cc). Bar, 1 μm.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2139880&req=5

Figure 2: Morphological analysis by TEM and FSC of TNF-α–induced trypanolysis in function of time (a, 1 h, b, 3 h, c, 4 h, d, 5 h). Purified trypanosomes were incubated for various periods of time in PSG (pH 8.0) in the presence or absence of 105 U/ ml TNF-α. (A) TEM analysis of TNF-α–treated T. brucei parasites. Swelling of organelles and lysis of parasites was recorded from 4 h of incubation onwards (Ac). (B) TEM analysis of nontreated T. brucei parasites. No lysis was observed. (C) FSC of TNF-α–treated T. brucei parasites. A major shift to the left of the FSC spectrum was observed from 4 h of incubation onwards (Cc). Bar, 1 μm.
Mentions: To study the morphological alterations that may occur during trypanolysis, TNF-α–treated parasites were analyzed by TEM and flow cytometry (FSC analysis). Concordant with the lysis experiments, TNF-α–induced morphological alterations occurred suddenly and progressed very fast (Fig. 2). Indeed, after 1 to 3 h of incubation with TNF-α, TEM analysis of the parasites revealed no major morphological changes (Fig. 2, Aa and Ab) and only a minor shift in FSC signals (∼5%) was recorded by flow cytometric analysis after 3 h of incubation (Fig. 2 Cb). At this time point, light microscopy analysis only indicated that a minor population became nonmotile. After 4 h, an important part of the trypanosome population analyzed in TEM manifested gross morphological alterations in the presence of TNF-α. As shown in Fig. 2 Ac, normal cells were observed in the vicinity of cells with swollen organelles and ruptured plasma membranes, reminiscent of an osmotic shock treatment. Concomitantly, the FSC signal of a major part of the parasites shifted to the left (Fig. 2 Cc) and indicated a trypanolysis of ∼40%. After 5 h of incubation, TEM analysis showed a far progressed lysis, although some completely intact cells were still found to be present (Fig. 2 Ad). FSC analysis indicated a trypanolysis in the range of 85% (Fig. 2 Cd). Control parasites that were incubated in the absence of TNF-α and analyzed in TEM showed no changes in morphology during the course of this experiment (Fig. 2 B, a–d). During trypanolysis experiments, we never recorded a TNF-α specific lysis >85%, not even when incubations were performed for periods up to 8 h. This observation indicates that within an apparently morphologically homogenous population of monomorphic trypanosomes, there is a heterogeneity with regard to TNF-α sensitivity.

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