losartan-potassium and Trypanosomiasis--African

Topics: Adolescent; Adult; Anemia; Anemia, Hypochromic; Anemia, Megaloblastic; Animals; Child; Child, Preschool; Dapsone; Drug Combinations; Erythropoietin; Female; Hookworm Infections; Humans; Infant; Iron-Dextran Complex; Leishmaniasis, Visceral; Macaca mulatta; Malaria; Male; Mice; Middle Aged; Protein-Energy Malnutrition; Pyrimethamine; Schistosomiasis; Socioeconomic Factors; Tropical Medicine; Trypanosomiasis, African

Anemia generated from African trypanosome infection is considered an important symptom in humans and in domestic animals. In order to recover from anemia, the process of erythropoiesis is essential. Erythropoiesis is affected by erythropoietin (EPO), an erythropoietic hormone, supplying iron and inflammatory and proinflammatory cytokines. However, the role of these factors in erythropoiesis during African trypanosome infection remains unclear. In the present study, we analyze how erythropoiesis is altered in anemic Trypanosoma brucei brucei (interleukin-tat 1.4 strain [ILS])-infected rats. We report that the packed cell volume (PCV) of blood from ILS-infected rats was significantly lower 4 days after infection, whereas the number of reticulocytes, as an index of erythropoiesis, did not increase. The level of EPO mRNA in ILS-infected rats did not increase from the third day to the sixth day after infection, the same time that the PCV decreased. Kidney cells of uninfected rats cultured with ILS trypanosome strain for 8 hr in vitro decreased EPO mRNA levels. Treatment of both ILS and cobalt chloride mimicked hypoxia, which restrained the EPO-production-promoting effect of the cobalt. Messenger RNA levels of β-globin and transferrin receptor, as markers of erythropoiesis in the bone marrow, also decreased in ILS-infected rats. Levels of hepcidin mRNA, which controls the supply of iron to the marrow in liver, were increased in ILS-infected rats; however, the concentration of serum iron did not change. Furthermore, mRNA levels of interleukin-12, interferon-γ, tumor necrosis factor-α, and macrophage migration inhibitory factor in the spleen, factors that have the potential to restrain erythropoiesis in bone marrow, were elevated in the ILS-infected rats. These results suggest that ILS infection in rats affect erythropoiesis, which responds by decreasing EPO production and restraining its function in the bone marrow.

Topics: Anemia; Animals; Cells, Cultured; Cytokines; Erythropoiesis; Erythropoietin; Hematocrit; Kidney; Male; Oxidants; Phenylhydrazines; Rats; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Trypanosoma brucei brucei; Trypanosomiasis, African

The postgenomic era has revolutionized approaches to defining host-pathogen interactions and the investigation of the influence of genetic variation in either protagonist upon infection outcome. We analyzed pathology induced by infection with two genetically distinct Trypanosoma brucei strains and found that pathogenesis is partly strain specific, involving distinct host mechanisms. Infections of BALB/c mice with one strain (927) resulted in more severe anemia and greater erythropoietin production compared to infections with the second strain (247), which, contrastingly, produced greater splenomegaly and reticulocytosis. Plasma interleukin-10 (IL-10) and gamma interferon levels were significantly higher in strain 927-infected mice, whereas IL-12 was higher in strain 247-infected mice. To define mechanisms underlying these differences, expression microarray analysis of host genes in the spleen at day 10 postinfection was undertaken. Rank product analysis (RPA) showed that 40% of the significantly differentially expressed genes were specific to infection with one or the other trypanosome strain. RPA and pathway analysis identified LXR/RXR signaling, IL-10 signaling, and alternative macrophage activation as the most significantly differentially activated host processes. These data suggest that innate immune response modulation is a key determinant in trypanosome infections, the pattern of which can vary, dependent upon the trypanosome strain. This strongly suggests that a parasite genetic component is responsible for causing disease in the host. Our understanding of trypanosome infections is largely based on studies involving single parasite strains, and our results suggest that an integrated host-parasite approach is required for future studies on trypanosome pathogenesis. Furthermore, it is necessary to incorporate parasite variation into both experimental systems and models of pathogenesis.

Topics: Anemia; Animals; Erythropoietin; Gene Expression Profiling; Genetic Variation; Interferon-gamma; Interleukin-10; Interleukin-12; Macrophage Activation; Mice; Mice, Inbred BALB C; Reticulocytosis; Splenomegaly; Trypanosoma brucei brucei; Trypanosomiasis, African

The effect of erythropoietin treatment on Trypanosoma congolense infection in mice was studied. Survival rates of mice were dramatically improved by treatment with recombinant human erythropoietin (r-hu-EPO; 5,000 U/kg) when infected with 1,000 cells of T. congolense IL3000 (P < 0.05). All the untreated mice infected with T. congolense IL3000 died by day 9 of infection; however, 100%, 50%, and 25% of the mice treated with r-hu-EPO for 8 days survived to day 20, day 40, and day 60 of the parasitical infection, respectively. Anti-8-hydroxy-2'-deoxyguanosine antibody, a biomarker for oxidative damage of DNA, yielded positive reactions in the cytoplasm of the parasites recovered from the mice treated with r-hu-EPO. These results, taken together, indicate that erythropoietin administration is effective for the treatment of T. congolense infection.

Topics: Anemia; Animals; Antibodies, Monoclonal; DNA Primers; DNA Probes; Erythropoietin; Female; Gene Expression Profiling; Hematocrit; Mice; Mice, Inbred C57BL; Parasitemia; Pentamidine; Polymerase Chain Reaction; Receptors, Erythropoietin; Recombinant Proteins; Survival Analysis; Time Factors; Trypanosoma congolense; Trypanosomiasis, African

Acute Trypanosoma congolense infection induced moderate, transient anemia in N'Dama cattle (trypanotolerant) and severe anemia in Boran cattle (trypanosusceptible). Erythropoietin receptor (EpoR) was cloned and sequenced from the two breeds of cattle. A single position mutation of Tyr in the Boran to His in the N'Dama predicted amino acid sequence was revealed. The mRNA transcription of erythropoietin (Epo) in kidneys and EpoR in the bone marrow of infected cattle was determined by competitive reverse transcription and the polymerase chain reaction (RT-PCR). Though Epo mRNA transcription increased in the kidneys during infection, the increase was not significantly different (p>0.05) between the two breeds of infected cattle. The level of EpoR transcripts in the bone marrow of infected N'Damas was significantly higher (p<0.05) than that detected in the marrows from infected Boran cattle. While infection seem to increase levels of transcription of IL-1alpha and beta, and TNFalpha in kidneys from both Boran and N'Dama cattle, no significant difference was detected in the level of mRNAs of these cytokines in the kidney from the two breed of cattle. The amount of IFNgamma mRNA transcripts were not changed with infection in N'Dama cattle, while on the contrary a significant higher levels of IFNgamma was found in kidneys from infected Boran cattle as compared to the other groups. A significant (p<0.05) increase in the levels of IL-1alpha and beta, and IFNgamma mRNA transcripts were detected in the marrows of infected Borans as compared to the infected N'Dama cattle. In this study the increase in the level of TNFalpha mRNA in the marrows of the two infected breeds was not different. This implies there is no negative effect of TNFalpha on hematopoiesis during acute infection. These findings suggest that the levels of Epo and EpoR in the infected Boran cattle were inadequate for their degree of anemia, which might be due in part to high expression of IFNgamma during acute infection with T. congolense.

Topics: Acute Disease; Amino Acid Sequence; Animals; Blood Cell Count; Bone Marrow; Cattle; Cell Count; DNA, Complementary; Erythropoietin; Female; Gene Expression; Interferon-gamma; Interleukin-1; Kidney; Male; Molecular Sequence Data; Parasitemia; Receptors, Erythropoietin; RNA, Messenger; Sequence Analysis, DNA; Trypanosoma congolense; Trypanosomiasis, African; Tumor Necrosis Factor-alpha

The cDNA coding for the soluble form of bovine stem cell factor (boSCFAla165) was cloned and recombinant protein was produced in bacteria as a histidine tagged-protein. The protein was purified from the inclusion bodies in one step by metal chelation chromatography under denaturing conditions. Recombinant bovine SCF was shown to act synergistically with interleukin 3 (IL-3) and erythropoietin (EPO) in stimulating the growth of bone marrow progenitor cells such as colony forming units-granulocyte macrophage (CFU-GM) and burst forming units-erythroid (BFU-E). Analysis of SCF mRNA expression by reverse transcription-polymerase chain reaction (RT-PCR) revealed that the transcripts were detectable in bone marrow, lymph nodes and spleen of cattle, and that the level of transcription was upregulated in lymph nodes of cattle infected with Trypanosoma congolense. Two isoforms of SCF mRNA were amplified by RT-PCR. The availability of recombinant bovine SCF provides a valuable tool for studying the role of SCF in the development, growth and differentiation of bovine hematopoietic cells.

Topics: Animals; Bone Marrow; Cattle; Cattle Diseases; Cell Differentiation; Cloning, Molecular; DNA Primers; Drug Synergism; Erythroid Precursor Cells; Erythropoietin; Escherichia coli; Gene Expression; Granulocyte-Macrophage Colony-Stimulating Factor; Interleukin-3; Lymph Nodes; Polymerase Chain Reaction; Recombinant Proteins; RNA, Messenger; Spleen; Stem Cell Factor; Trypanosoma congolense; Trypanosomiasis, African; Up-Regulation

A bioassay was used to measure erythropoietin (EPO) concentrations in calves with haemorrhagic anaemia due to blood loss and in calves with anaemia due to Trypanosoma congolense infection. The bioactivity of EPO was measured in the assay by its stimulatory effect on 125I-deoxyuridine incorporation in spleen cells from phenylhydrazine-treated mice. Erythropoietin concentrations in blood-volume-depleted calves were elevated 6 h after blood loss, maximal (1225 mU/ml) at 33 h and below detection limits at 72 h. Reticulocytes (0.05 +/- 0.1%) appeared in blood by 72 h, peaked at 120 h and disappeared from the circulation by 7 days after bleeding. The packed cell volume (PCV) started increasing at 120 h and reached near pre-bleeding values by 14 days. In T. congolense-infected calves, parasites were first detected in the peripheral blood 12 days post-infection (dpi). Parasitaemia peaked (5 x 10(5) trypanosomes/ml of blood) at 15-18 dpi and, thereafter, several waves of parasitaemia were observed, but the peaks gradually diminished. Undiluted plasma from T. congolense-infected calves suppressed 125I-deoxyuridine incorporation into spleen cells from 13 dpi onwards. The suppressive effect of plasma was partly negated by five-fold dilution, which made possible the detection of increased EPO concentrations during the acute and chronic stages of the anaemia. The highest EPO peaks, reaching 2300 mU/ml in one calf, were detected during the chronic stage of the infection. At 15-39 dpi, there was a transient bone-marrow erythropoietic response characterized by an increase in mean corpuscular volume and a decrease in mean corpuscular haemoglobin concentration but with few reticulocytes (0.4%). However, from 76 dpi onwards, this response waned despite low PCV and elevated EPO concentrations. These results suggest that there is an ineffective erythroid response in the face of elevated EPO concentrations during bovine trypanosomiasis. The negative effect of plasma and serum from trypanosome-infected calves on the in-vitro bioactivity of EPO suggests the presence of inhibitory factors.

Topics: Animals; Biological Assay; Cattle; Cells, Cultured; Deoxyuridine; Erythropoietin; Female; Hematologic Tests; Iodine Radioisotopes; Male; Mice; Mice, Inbred BALB C; Spleen; Trypanosoma congolense; Trypanosomiasis, African; Trypanosomiasis, Bovine