Cytokine gene expression and pathology in mice experimentally infected with different isolates of Trypanosoma evansi

Histopathology and virulence of an in vitro-adapted Trypanosoma evansi TEDC 953 strain (Thailand isolate) in mice

Background and Aim

Trypanosoma evansi is a blood and tissue protozoan parasite affecting domestic and wild animals. The T. evansi Thai strain, namely, T. evansi from dairy cattle number 953 (TEDC 953) strain, has been successfully isolated from dairy cattle and cultivated in vitro. The in vitro-cultivated parasite is useful for biological studies, evaluation of novel chemotherapeutic agents, and production of antigens for diagnostic tests. This study aimed to observe the histopathology and virulence of an in vitro-adapted T. evansi TEDC 953 strain in vivo.

Materials and Methods

The histopathology and virulence of the TEDC 953 strain were clarified in mice. Six mice were infected with 1 × 105 trypomastigotes of TEDC 953 strain intraperitoneally, and four mice were in the negative control. Parasitemia was monitored daily, and the mice were euthanized on 30 days post-infection (DPI). Internal organs were collected for histopathological examination using hematoxylin and eosin staining.

Results

Histopathological lesions were found in the liver, lung, heart, kidney, spleen, and brain of the inoculated mice. The main histopathological feature was lymphoplasmacytic inflammation in parenchyma and perivascular areas of multiple organs, and the severity of histopathological changes was related to the presence of trypomastigotes in the regional vessels. Granulomatous inflammation was seen in meninges, pleura, renal capsule, renal pelvis, and spleen of some infected mice. Four mice died at 17, 24, 26, and 27 DPI with an average parasitemia of 4.05 × 1011 trypomastigotes/mL. The average survival time was 23.5 DPI (mice = 4).

Conclusion

This study confirmed that the TEDC 953 strain is infectious and pathogenic in mice after the continuously cultivated in vitro. To replace the use of experimental animals, the in vitro-cultivated parasite can be used instead in further studies.

Comparative pathology of experimental infection with four isolates of Trypanosoma evansi in Wistar albino Rats

In the present study, pathological changes due to experimental infection with four isolates of T. evansi were studied in rats to know the pathogenicity. Male Wistar albino rats (140) were divided in five groups of 28 rats each (4 isolate groups and 1 control group). Each rat was infected with 1×105 T. evansi from buffalo, dog, leopard and lion isolates and normal saline in control group by intraperitoneal route. Four rats were sacrificed on Day 1 (D1) to D7 post infection in each group and collected blood was for microscopic examination and tissues for pathology. Blood smear examination revealed presence of trypanosomes on D3, D4, D5 and D5 in buffalo, dog, leopard and lion isolates, respectively. All the T. evansi infected rats showed hypoglycaemia and increased blood urea nitrogen in serum. Rats showed clinical signs with dullness, lethargy and hunched back on D7. Liver showed vacuolar degeneration, congestion of blood vessels and infiltration of mononuclear cells on D7 in buffalo, dog, lion isolates, and no changes in leopard isolate infected rats. Kidney, spleen, lung and testis revealed pathological changes in buffalo and dog isolates. Trypanosomes were present in the endocardium of heart in buffalo isolate infected rats. Immunohistopathology revealed presence of trypanosome antigens in the blood vessels of liver, and spleen. Thus, based on trypanosome counts, serum glucose, blood urea nitrogen and pathological changes, there was variation between these isolates and revealed pathogenicity in ascending order as leopard, lion, dog and buffalo isolates in rats.

Characterization of MDCK cells and evaluation of their ability to respond to infectious and non-infectious stressors

The Madin-Darby Canine Kidney (MDCK) cell line is widely used as epithelial cell model in studies ranging from viral infection to environmental pollutants, and vaccines production. However, little is known about basal expression of genes involved in innate immunity, and the ability to respond to infectious and non-infectious stressors. Therefore, the aims of our study were to evaluate the basal level of expression of pivotal genes in the innate immune response and cell cycle regulation, as well as to evaluate the ability of this cell line to respond to infectious or non-infectious stressors. As surmised in our working hypothesis, we demonstrated the constitutive expression of genes involved in the innate immune response and cell defense alike, including TLRs, Interleukins, Myd88, p65/NF-kB and p53. Moreover, we described the ability of this cell line to respond to LPS and cadmium (Cd2+) in terms of gene expression and cytokine release. These data confirm the possibility of using this cell line as a model in studies of host/pathogen interaction and response to non-infectious stressors.

Immunophenotyping and cytokine gene expression in experimental intramammary infection with staphylococcal species in mice

Immunophenotyping and proinflammatory cytokine gene expression in mice mammary gland inoculated with Staphylococcus epidermidis, S. chromogenes, S. haemolyticus and S. aureus isolated from bovine milk were studied. Swiss albino mice were inoculated with 50 μl (2×104 CFU organisms) per mammary gland (L4, L5, R4 and R5) through intramammary route. Mice were sacrificed at 6, 12, 24, 48, 72 and 96 h, and blood and mammary gland tissues were collected for blood immunophenotyping and cytokine gene expression studies, respectively. CD4+ cells increased in S. aureus, S. epidermidis, S. haemolyticus and decreased in S. chromogenes inoculated mice. CD8 + cells increased in S. epidermidis compared to other groups. Proinflammatory cytokines showed increased expression of IL-1β (6 folds), IL-4 (3 folds), IL-6 (1 fold), IL-12 (5 folds), TNF-α (5 folds) and IFN-γ (2 folds) in S. aureus inoculated mice. S. epidermidis revealed 2 fold increase in IL-1β and IL-4, and 1 fold increase in IL-6, IL-12, TNF-α and IFN-γ. S. chromogenes showed increased expression of 2 folds in IL-1β, IFN-γ; 3 folds in IL-4, IL-6, TNF-α and 7 folds in IL-12. S. haemolyticus revealed 2 folds increase in IL-1β, IL-12, TNF-α; 3 folds in IL-6 and 5 folds in IL-4. Hence, S. aureus caused severe mastitis in mice when compared to three coagulase negative staphylococcal (CNS) species. The proinflammatory cytokines (IL-1β, IL-4 and IFN-γ) can be used as an indicator for early detection and mice can be used as mastitis model to study CNS mastitis.

Salivarian Trypanosomosis: A Review of Parasites Involved, Their Global Distribution and Their Interaction With the Innate and Adaptive Mammalian Host Immune System

Salivarian trypanosomes are single cell extracellular parasites that cause infections in a wide range of hosts. Most pathogenic infections worldwide are caused by one of four major species of trypanosomes including (i) Trypanosoma brucei and the human infective subspecies T. b. gambiense and T. b. rhodesiense, (ii) Trypanosoma evansi and T. equiperdum, (iii) Trypanosoma congolense and (iv) Trypanosoma vivax. Infections with these parasites are marked by excessive immune dysfunction and immunopathology, both related to prolonged inflammatory host immune responses. Here we review the classification and global distribution of these parasites, highlight the adaptation of human infective trypanosomes that allow them to survive innate defense molecules unique to man, gorilla, and baboon serum and refer to the discovery of sexual reproduction of trypanosomes in the tsetse vector. With respect to the immunology of mammalian host-parasite interactions, the review highlights recent findings with respect to the B cell destruction capacity of trypanosomes and the role of T cells in the governance of infection control. Understanding infection-associated dysfunction and regulation of both these immune compartments is crucial to explain the continued failures of anti-trypanosome vaccine developments as well as the lack of any field-applicable vaccine based anti-trypanosomosis intervention strategy. Finally, the link between infection-associated inflammation and trypanosomosis induced anemia is covered in the context of both livestock and human infections.

Cytokine gene expression and pathology in experimental Pasteurella multocida infection in mice

The study was conducted to know the pathology and cytokine gene expression studies in experimental infection with Pasteurella multocida in mice. Swiss albino mice (20) were inoculated with P. multocida (200 μl of 1 × 108 cfu/ml) and control mice with sterile PBS intraperitoneally and sacrificed 4 mice at 6, 12, 18 and 24 h. Mice showed dullness, lethargy and unable to move at 18 and 24 h after inoculation. Histopathology revealed changes in liver, kidney, spleen, lung and no observable changes in heart and abdominal muscles. Liver showed septicemia condition and acute bronchopneumonia of lung at 24 h. TNF-α gene showed 20-fold increase in liver and spleen and 5-folds in kidney. There was upregulation of pro-inflammatory cytokines in liver, kidney, spleen and IL–10 gene at later periods of infection which is a new finding, needs further study. Thus, the present study indicated that increase in tissue cytokine gene expression concurred with histopathological changes were attributed to the pathogenesis of Pasteurellosis in mice.