Frequency of diminazene-resistant trypanosomes in populations of Trypanosoma congolense arising in infected animals following treatment with diminazene aceturate

Diminazene Aceturate Stabilizes Atherosclerotic Plaque and Attenuates Hepatic Steatosis in apoE-Knockout Mice by Influencing Macrophages Polarization and Taurine Biosynthesis

Atherosclerosis and nonalcoholic fatty liver disease are leading causes of morbidity and mortality in the Western countries. The renin-angiotensin system (RAS) with its two main opposing effectors, i.e., angiotensin II (Ang II) and Ang-(1-7), is widely recognized as a major regulator of cardiovascular function and body metabolic processes. Angiotensin-converting enzyme 2 (ACE2) by breaking-down Ang II forms Ang-(1-7) and thus favors Ang-(1-7) actions. Therefore, the aim of our study was to comprehensively evaluate the influence of prolonged treatment with ACE2 activator, diminazene aceturate (DIZE) on the development of atherosclerotic lesions and hepatic steatosis in apoE-/- mice fed a high-fat diet (HFD). We have shown that DIZE stabilized atherosclerotic lesions and attenuated hepatic steatosis in apoE-/- mice fed an HFD. Such effects were associated with decreased total macrophages content and increased α-smooth muscle actin levels in atherosclerotic plaques. Moreover, DIZE changed polarization of macrophages towards increased amount of anti-inflammatory M2 macrophages in the atherosclerotic lesions. Interestingly, the anti-steatotic action of DIZE in the liver was related to the elevated levels of HDL in the plasma, decreased levels of triglycerides, and increased biosynthesis and concentration of taurine in the liver of apoE-/- mice. However, exact molecular mechanisms of both anti-atherosclerotic and anti-steatotic actions of DIZE require further investigations.

To the Skin and Beyond: The Immune Response to African Trypanosomes as They Enter and Exit the Vertebrate Host

African trypanosomes are single-celled extracellular protozoan parasites transmitted by tsetse fly vectors across sub-Saharan Africa, causing serious disease in both humans and animals. Mammalian infections begin when the tsetse fly penetrates the skin in order to take a blood meal, depositing trypanosomes into the dermal layer. Similarly, onward transmission occurs when differentiated and insect pre-adapted forms are ingested by the fly during a blood meal. Between these transmission steps, trypanosomes access the systemic circulation of the vertebrate host via the skin-draining lymph nodes, disseminating into multiple tissues and organs, and establishing chronic, and long-lasting infections. However, most studies of the immunobiology of African trypanosomes have been conducted under experimental conditions that bypass the skin as a route for systemic dissemination (typically via intraperitoneal or intravenous routes). Therefore, the importance of these initial interactions between trypanosomes and the skin at the site of initial infection, and the implications for these processes in infection establishment, have largely been overlooked. Recent studies have also demonstrated active and complex interactions between the mammalian host and trypanosomes in the skin during initial infection and revealed the skin as an overlooked anatomical reservoir for transmission. This highlights the importance of this organ when investigating the biology of trypanosome infections and the associated immune responses at the initial site of infection. Here, we review the mechanisms involved in establishing African trypanosome infections and potential of the skin as a reservoir, the role of innate immune cells in the skin during initial infection, and the subsequent immune interactions as the parasites migrate from the skin. We suggest that a thorough identification of the mechanisms involved in establishing African trypanosome infections in the skin and their progression through the host is essential for the development of novel approaches to interrupt disease transmission and control these important diseases.

Effect of crude extracts of Moringa stenopetala and Artemisia absinthium on parasitaemia of mice infected with Trypanosoma congolense

Background

Treatment of trypanosomosis is currently facing a number of problems including toxicity of trypanocidal drugs and development of resistance by the parasites. These limitations have prompted the search for alternative active substances (such as of natural origin). The purpose of the study was to investigate the effect of extracts of Moringa stenopetala and Artemisia absinthium on Trypanosoma congolense in mice.

Methods

Swiss white male mice aged 8–12 weeks were divided into six experimental groups of six animals. Water and methanol extracts of the two plants were prepared. T. congolense was isolated from cattle at Ghibe valley (Ethiopia). All experimental mice received approximately 1 x 10⁵ trypanosomes in 0.2 ml of blood. Plant extracts were given orally to four groups (2 plant species and two extraction methods) at 400 mg/kg body weight for seven consecutive days. One group remained as distilled water treated control and the other as diminzene aceturate treated control. The effect of the extracts on levels of parasitaemia, body weight, packed cell volume (PCV) and mice survival was monitored for 25 days.

Results

All treatments have significantly reduced parasitaemia and helped improve body weight, PCV and survival of mice compared to the water-treated control (P < 0.01 in all cases). These effects were comparable to that with diminazene aceturate. No significant difference was observed in the reduction of parasitaemia between plant extract treatment groups. However, mice with extracts of A. absinthium had significantly higher body weight than those with extracts of M. stenopetala (P < 0.05).

Conclusions

The two plants have antitrypanosomal potential against T. congolense by reducing the levels of parasitaemia, maintaining good PCV and body weight, and prolonging the lives of infected animals.

Study on the susceptibility of Sahel goats to experimental Trypanosoma vivax infection

Sahel goats, also known as Borno whites are found in the northern semi-arid, tsetse free Sahel region of Nigeria. They are transported alongside cattle from this zone to all other zones in the country, including the tsetse-infested zones, for commercial purposes and are kept for some time in these tsetse-infested zones until they are sold. This study therefore assessed the susceptibility of this breed of goats to trypanosome infection and its response to treatment with Berenil. Six bucks were inoculated intravenously with Trypanosoma vivax through the jugular vein while two served as uninfected control. The mean pre-patent period was 4.5 days and increasing parasitaemia followed the establishment of infection. Onset of parasitaemia was associated with increase in rectal temperature in all the infected goats and the temperature peak coincided with the only parasitaemic peak second week post-infection. The infected goats were treated with Berenil (Hoechst, Germany) 3.5mg/kg body weight at 4 weeks post-infection. The packed cell volume (PCV) continued to fall from a mean 30.73+/-0.01% pre-infection to a mean 13.21+/-0.18% at 1 week post-treatment. Deaths were recorded for 4 of the infected goats 1 week post-treatment while the remaining two died 2 weeks post-treatment, not responding to treatment.

Standardised tests in mice and cattle for the detection of drug resistance in tsetse-transmitted trypanosomes of African domestic cattle

Resistance to the drugs used to control African animal trypanosomosis is increasingly recognised as a constraint to livestock production in sub-Saharan Africa. The most commonly used tests for detection of trypanocidal drug resistance are tests using mice or ruminants, but these suffer from lack of standardisation and hence it may be difficult to compare the results of different investigators. Tests in mice are less expensive than tests in ruminants, but while tests in mice they may be useful as a general guide to resistance in a geographic area they should not be extrapolated to cattle on an individual trypanosome level. Moreover, the commonly used protocols are too laborious for their application to large number of trypanosome isolates on an area-wide basis. This paper presents guidelines for standardised testing of trypanocidal drugs in vivo, and introduces a simplified single-dose test for use in mice, which is convenient for use in areas with limited laboratory facilities. The single-dose test is appropriate for characterisation of geographic areas in terms of trypanocidal drug resistance using large numbers of trypanosome isolates, for making comparisons between areas, and for monitoring changes in trypanocidal drug resistance over time. Multiple-dose tests may be used to determine the degree of resistance of individual stabilates to be determined precisely in mice are also described, but for logistical reasons these will rarely be conducted on more than a few stabilates, and testing of a larger number of stabilates in the single-dose test will generally provide more useful information. Finally, we describe tests in cattle that may be used to determine the efficacy of recommended curative doses of trypanocidal drugs for the treatment of infection with individual trypanosome isolates, including Trypanosoma vivax, which is rarely infective for mice.