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Morrison LJ, Steketee PC, Tettey MD, Matthews KR. Pathogenicity and virulence of African trypanosomes: From laboratory models to clinically relevant hosts. Virulence 2023; 14:2150445. [PMID: 36419235 DOI: 10.1080/21505594.2022.2150445] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 11/17/2022] [Indexed: 11/25/2022] Open
Abstract
African trypanosomes are vector-borne protozoa, which cause significant human and animal disease across sub-Saharan Africa, and animal disease across Asia and South America. In humans, infection is caused by variants of Trypanosoma brucei, and is characterized by varying rate of progression to neurological disease, caused by parasites exiting the vasculature and entering the brain. Animal disease is caused by multiple species of trypanosome, primarily T. congolense, T. vivax, and T. brucei. These trypanosomes also infect multiple species of mammalian host, and this complexity of trypanosome and host diversity is reflected in the spectrum of severity of disease in animal trypanosomiasis, ranging from hyperacute infections associated with mortality to long-term chronic infections, and is also a main reason why designing interventions for animal trypanosomiasis is so challenging. In this review, we will provide an overview of the current understanding of trypanosome determinants of infection progression and severity, covering laboratory models of disease, as well as human and livestock disease. We will also highlight gaps in knowledge and capabilities, which represent opportunities to both further our fundamental understanding of how trypanosomes cause disease, as well as facilitating the development of the novel interventions that are so badly needed to reduce the burden of disease caused by these important pathogens.
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Affiliation(s)
- Liam J Morrison
- Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, UK
| | - Pieter C Steketee
- Roslin Institute, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, UK
| | - Mabel D Tettey
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Keith R Matthews
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
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Caljon G, Van Den Abbeele J, Stijlemans B, Coosemans M, De Baetselier P, Magez S. Tsetse fly saliva accelerates the onset of Trypanosoma brucei infection in a mouse model associated with a reduced host inflammatory response. Infect Immun 2006; 74:6324-30. [PMID: 16954393 PMCID: PMC1695494 DOI: 10.1128/iai.01046-06] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Tsetse flies (Glossina sp.) are the vectors that transmit African trypanosomes, protozoan parasites that cause human sleeping sickness and veterinary infections in the African continent. These blood-feeding dipteran insects deposit saliva at the feeding site that enables the blood-feeding process. Here we demonstrate that tsetse fly saliva also accelerates the onset of a Trypanosoma brucei infection. This effect was associated with a reduced inflammatory reaction at the site of infection initiation (reflected by a decrease of interleukin-6 [IL-6] and IL-12 mRNA) as well as lower serum concentrations of the trypanocidal cytokine tumor necrosis factor. Variant-specific surface glycoprotein-specific antibody isotypes immunoglobulin M (IgM) and IgG2a, implicated in trypanosome clearance, were not suppressed. We propose that tsetse fly saliva accelerates the onset of trypanosome infection by inhibiting local and systemic inflammatory responses involved in parasite control.
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Affiliation(s)
- Guy Caljon
- Unit of Cellular and Molecular Immunology, Flanders Interuniversity Institute for Biotechnology (VIB), Vrije Universiteit Brussel (VUB), Pleinlaan 2, B-1050 Brussels, Belgium.
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Magez S, Stijlemans B, Caljon G, Eugster HP, De Baetselier P. Control of experimental Trypanosoma brucei infections occurs independently of lymphotoxin-alpha induction. Infect Immun 2002; 70:1342-51. [PMID: 11854219 PMCID: PMC127790 DOI: 10.1128/iai.70.3.1342-1351.2002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Trypanosome infections are marked by severe pathological features, including anemia, splenomegaly, and suppression of T-cell proliferation. We have used lymphotoxin-alpha-deficient (LT-alpha(-/-)) mice, as well as LT-alpha-tumor necrosis factor-double-deficient (LT-alpha(-/-) TNF(-/-)) mice, to analyze the contributions of these related cytokines in both induction of trypanosomosis-associated immunopathology and infection control. Moreover, as the cytokine-deficient mice used have no detectable lymph nodes and lack germinal-center formation upon immune stimulation, we have analyzed the functional importance of both the lymph nodes and spleen during experimental Trypanosoma brucei infections. First, we show that the absence of LT-alpha does not significantly alter early trypanosomosis development or pathology but does result in better control of late-stage parasitemia levels and slightly prolonged survival. This increased survival of infected LT-alpha(-/-) mice coincides with the appearance of increased chronic-stage anti-trypanosome immunoglobulin M (IgM)-IgG2a serum titers that are generated in the absence of functional peripheral lymphoid tissue and do not require germinal-center formation. Second, we show that splenectomized mice control their parasitemia to the same extent as fully immune-competent littermates. Finally, using LT-alpha(-/-) TNF(-/-) double-deficient mice, we show that in these mice T. brucei infections are very well controlled during the chronic infection stage and that infection-induced pathology is minimized. Together, these findings indicate that while increased IgM-IgG2a anti-trypanosome antibody titers (generated in the absence of LT-alpha, peripheral lymph nodes, and germinal-center formation) coincide with improved parasitemia control, it is TNF that has a major impact on trypanosomosis-associated immunopathology.
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Affiliation(s)
- S Magez
- Department of Immunology, Parasitology and Ultrastructure, Vlaams Interuniversitair Instituut voor Biotechnologie, Vrije Universiteit Brussel, Paardenstraat 65, B-1640 Sint Genesius Rode, Belgium.
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Wainszelbaum M, Isola E, Wilkowsky S, Cannata JJ, Florin-Christensen J, Florin-Christensen M. Lysosomal phospholipase A1 in Trypanosoma cruzi: an enzyme with a possible role in the pathogenesis of Chagas' disease. Biochem J 2001; 355:765-70. [PMID: 11311140 PMCID: PMC1221793 DOI: 10.1042/bj3550765] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We found that, as in African trypanosomes, endogenous phospholipase A(1) (Plase A(1)) activity can catalyse extensive deacylation of phospholipids upon cell death in all life stages of Trypanosoma cruzi. A major lysosomal Plase A(1) was purified and characterized. The enzyme products can explain the lesions surrounding degenerating T. cruzi cells in host tissues. Thus Plase A(1) emerges as a target to block pathogenesis in trypanosomal infections.
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Affiliation(s)
- M Wainszelbaum
- Department of Microbiology, University of Buenos Aires (UBA) School of Medicine, Paraguay 2155, piso 13, (RA-2111) Buenos Aires, Argentina
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Abstract
Bloodstream forms of African trypanosomes are dependent on their host for fatty acids, choline and other components of membrane lipids. The bulk of their choline requirement is met by their ability to take up lysophospholipids from the host tissue fluids. Trypanosoma brucei has ocyltransferose and phospholipase A(1) activities for the metabolism of exogenous lysophospholipids. The rate of uptake of lysophospholipids can be controlled by changes in the extrocellulor concentration of fatty ocyl-coenzyme A, and this control has potential for chemotherapy.
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Affiliation(s)
- A Mellors
- Department of Chemistry and Biochemistry, University of Guelph, Guelph, Ontario NIG2WI, Canada
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Diffley P, Straus DC. Biochemical and immunological characterization of the variant surface coat glycoprotein shed by African trypanosomes. Infect Immun 1986; 53:166-72. [PMID: 3721578 PMCID: PMC260092 DOI: 10.1128/iai.53.1.166-172.1986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
As the variant surface coat glycoprotein (VSG) was shed from Trypanosoma brucei rhodesiense into the blood of infected rats, it was biochemically characterized and compared with VSG that had been purified from trypanosomal homogenates. To determine if VSG was in association with lipid, membranes and lipoproteins in plasma of infected rats (IRP), VSG isolated from plasma (PVSG), and VSG isolated from trypanosomal homogenates (HVSG) were all concentrated by ultracentrifugation and assayed for the presence of VSG by radial immunodiffusion (minimum level of detection, 25 micrograms/ml) and by immunoelectroblots (minimum level of detection, 1 microgram/ml). Crimson red was used to detect lipid (minimum level of detection, 10 micrograms per sample) in electrophoresed samples. The VSG was neither concentrated with membrane or lipoprotein fractions nor stained by lipid crimson. Lipids from normal rat plasma, IRP, trypanosomal homogenates, HVSG, and PVSG were also extracted and separated by thin-layer chromatography (minimum level of detection, 20 micrograms of trypanosomal phospholipid per sample). The trypanosomal homogenates had five bands as detected by iodine vapors, of which three were phospholipids as detected by molybdenum blue. Both normal rat plasma and IRP had identical patterns of bands with a single phospholipid. The PVSG had one neutral lipid contaminant that apparently was not physically associated with the shed surface coat. The HVSG contained no lipids at all. Therefore, no evidence was obtained to implicate an association between membranes and VSG, once the latter had been shed into the blood of infected hosts. From immunoelectroblots of denatured material, it was determined that both HVSG and PVSG had the same reduced molecular weight. From molecular sieve column chromatography, however, it was determined that VSG released during the homogenization of trypanosomes is a noncovalently linked dimer, whereas that shed in the blood is apparently a trimer. This difference in native structure made no difference in immunological effect. Administered in a regimen that mimicked what the host encounters during a first peak of parasitemia, both HVSG and PVSG induced nonspecific proliferation of splenic lymphocytes and production of unelicited antibodies without the generation of nonspecific immunosuppression. This polyclonal activation of lymphocytes was not the result of contamination by exogenous pyrogen, because the activity was lost if VSG was immunologically absorbed from plasma.(ABSTRACT TRUNCATED AT 400 WORDS)
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van der Zee CE, van Dam RH, Dwinger RH, Nieuwenhuijs J, Zwart D. Flurbiprofen and immunosuppression of Trypanosoma brucei infection in the goat. Vet Immunol Immunopathol 1985; 8:341-50. [PMID: 3873746 DOI: 10.1016/0165-2427(85)90004-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Goats infected with Trypanosoma brucei and treated with the non-steroidal anti-inflammatory agent flurbiprofen, showed a marked increase in parasitaemia, followed in one of the four goats by death. The in vitro response to mitogens of peripheral blood lymphocytes and separated T- and B-lymphocytes from healthy goats treated with flurbiprofen was normal when compared with non-treated animals. T. brucei-infected goats, not treated with flurbiprofen, showed a marked immunosuppression which was mainly localized in the B-enriched lymphocyte fraction. A combination of T. brucei infection and treatment with flurbiprofen led to even more suppression, because the T-lymphocyte function was also suppressed. It is concluded that flurbiprofen first causes a rise in the parasitaemia and that this high parasitaemia is responsible for the observed immunosuppression.
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Kaggwa E, Munyua WK, Mugera GM. The role of the spleen in Trypanosoma brucei brucei infection in dogs. ZENTRALBLATT FUR VETERINARMEDIZIN. REIHE B. JOURNAL OF VETERINARY MEDICINE. SERIES B 1984; 31:470-9. [PMID: 6475405 DOI: 10.1111/j.1439-0450.1984.tb01325.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Rurangirwa FR, Musoke AJ, Nantulya VM, Tabel H. Immune depression in bovine trypanosomiasis: effects of acute and chronic Trypanosoma congolense and chronic Trypanosoma vivax infections on antibody response to Brucella abortus vaccine. Parasite Immunol 1983; 5:267-76. [PMID: 6408588 DOI: 10.1111/j.1365-3024.1983.tb00743.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Cattle were vaccinated with Brucella abortus (S19) vaccine during acute (25 days) and chronic (25 weeks) Trypanosoma congolense and chronic Trypanosoma vivax (25 weeks) infections in order to determine the effect of such infections on the antibody response to the vaccine. It was found that the specific antibody responses of IgG1 and IgG2 sub-classes were profoundly depressed (80%) in both the acute and chronic infections with T. congolense. Whereas IgM antibody response was also profoundly depressed (90%) in cattle with the acute infection, it was only 50% depressed in those with chronic infection. There was no depression of IgG1, IgG2, or IgM in cattle infected with T. vivax. These animals, however, had no detectable parasitaemia at the time of vaccination and thereafter. These results suggest that during acute infection with T. congolense depressive mechanisms could be acting on the afferent arm of the immune response, namely, antigen recognition and/or processing.
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Sealey M, Ramos C, Willms K, Ortiz-Ortiz L. Taenia solium: mitogenic effect of larval extracts on murine B lymphocytes. Parasite Immunol 1981; 3:299-307. [PMID: 6976548 DOI: 10.1111/j.1365-3024.1981.tb00408.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The effect of an extract (CE) obtained from Cysticercus cellulosae on the proliferation of lymphocytes was studied in cultures of murine spleen cells. The addition of CE to the cultures resulted in the highly significant uptake and incorporation of tritiated thymidine (3H-TdR) into DNA. This phenomena was dose-dependent, with doses lower and higher than the optimal concentration causing less marked effects. The kinetic peak of this response was found to occur on day 2 of culture. CE evoked a proliferative response in cultures of spleen cells from congenitally athymic (nu/nu) BALB/c mice. Cultures of bone marrow-derived (B) lymphocytes, generated by treatment of spleen cells with rabbit antithymocyte serum and complement, incorporated 3H-TdR to a degree similar to that of normal spleen cell cultures. CE did not induce the proliferation of thymocytes. To eliminate the possibility that the mitogenic effect of CE was due to LPS, we carried out experiments using Polymyxin B (PB). CE was mitogenic after treatment with PB which inactivated the LPD effect. In addition, CE elicited 3H-TdR uptake in spleen cells from the LPS nonresponsive C3H/HeJ mouse strain.
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Cunningham DS, Kuhn RE, Tarleton RL, Dunn RS. Trypanosoma cruzi: effect on B-cell-responsive and -responding clones. Exp Parasitol 1981; 51:257-68. [PMID: 6781919 DOI: 10.1016/0014-4894(81)90114-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Herbert WJ, Parratt D, Van Meirvenne N, Lennox B. An accidental laboratory infection with trypanosomes of a defined stock. II. Studies on the serological response of the patient and the identity of the infecting organism. J Infect 1980; 2:113-24. [PMID: 7185920 DOI: 10.1016/s0163-4453(80)91109-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Pickart LR, Thaler MM. Fatty acids, fibrinogen and blood flow: a general mechanism for hyperfibrinogenemia and its pathologic consequences. Med Hypotheses 1980; 6:545-57. [PMID: 6997706 DOI: 10.1016/0306-9877(80)90108-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Plasma fibrinogen is elevated in various stressful states and conditions in which active mobilization of free fatty acids (FFA) occurs. Reduction of plasma FFA by an assortment of hypolipidemic drugs is consistently followed by a decrease in the accompanying hyperfibrinogenemia. A direct link between FFA and fibrinogen has been demonstrated in animals, and in experiments employing incubated liver slices. Based on these clinical and experimental observations, we postulate that hepatic fibrinogen synthesis is stimulated by FFA. Since fibrinogen is a major determinant of whole blood viscosity, erythrocyte aggregation, and sludging of red cells in terminal and pre-terminal blood vessels, we propose that microcirculatory blood flow may be impaired in the presence of chronically elevated plasma FFA levls. Consequently, hypolipidemic drugs may be effective in prevention of circulatory complications associated with FFA-induced hyperfibrinogenemia.
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Henson JB, Noel JC. Immunology and pathogenesis of African animal trypanosomiasis. ADVANCES IN VETERINARY SCIENCE AND COMPARATIVE MEDICINE 1979; 23:161-82. [PMID: 550706 DOI: 10.1016/b978-0-12-039223-0.50013-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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