Presence of amastigotes in the central nervous system of hamsters infected with Leishmania sp

Leishmania hide-and-seek: Parasite amastigotes in the choroid plexus of a dog with neurological signs in an endemic municipality in Brazil

A female adult mixed-breed stray dog presented with hind limb paraparesis and clinical signs of visceral leishmaniasis. The cerebrospinal fluid presented signs of blood-brain barrier disruption. Both spleen and brain were positive for Leishmania spp. DNA. Besides inflammation, in situ hybridization and immunohistochemistry (IHC) revealed the presence of intracellular amastigotes in the choroid plexus (CP). Despite other studies that revealed parasite DNA, the current study describes the presence of Leishmania within the brain of a naturally infected dog, specifically in CP, with no previous reports in the Americas, and suggests the CP as a possible pathway to parasite entry into the brain.

Main lesions in the central nervous system of dogs due to Leishmania infantum infection

Background

Canine visceral leishmaniasis (CVL) is endemic in São Luís Maranhão/Brazil and it leads a varied clinical picture, including neurological signs.

Results

Histopathological evaluation showed that 14 dogs exhibited pathological alterations in at least one of the analyzed areas. Of these, mononuclear inflammatory reaction was the most frequent, although other lesions, such as hemorrhage, chromatolysis and gliosis were also observed. The presence of L. infantum amastigotes was confirmed in eight dogs, identified in four regions: telencephalon, hippocampus, thalamus and caudal colliculus, but only one presented neurological signs. Polymerase chain reaction results detected the DNA of the parasite in 11 samples from seven dogs. The positive areas were the telencephalon, thalamus, hippocampus, cerebellum, caudal and rostral colliculus.

Conclusion

These results reveal that during canine visceral leishmaniasis, the central nervous system may display some alterations, without necessarily exhibiting clinical neurological manifestations. In addition, the L. infantum parasite has the ability to cross the blood brain barrier and penetrate the central nervous system.

Does Leishmaniasis disease alter the parenchyma and protein expression in salivary glands?

Leishmaniasis is considered a serious public health problem in several regions in Brazil and worldwide. This research aimed to perform a histopathological and proteomic study of parotid, submandibular and sublingual glands of BALB/c mice infected by Leishmania (L) infantum chagasi using histological, immunohistochemical and epifluorescence techniques. Twelve isogenic BALB/c male mice, around six- to eight-weeks old, were separated into two groups: the animals of the control group were injected with 0.15 ml of NaCl, while those in the experimental group were inoculated with 5 × 10(6) amastigote forms of Leishmania (L) infantum chagasi by the ip route. After 50 days, animals were euthanized and major salivary glands were collected to perform histological, immunohistochemical and epifluorescence techniques using anti-Caspase-2, anti-Ki-67 and anti-β-catenin antibodies, respectively. The histological and morphometric evaluation showed clusters of mononuclear inflammatory cells and a higher area and perimeter of the parotid gland. However, none of the salivary glands had morphophysiological impairment. There was no immunoreactivity to the anti-caspase-2 antibody and Ki67 expression in acinar and ductal cells in both groups. According to the immunofluorescence staining, the β-catenin antibodies did not show nuclear expression, suggesting no uncontrolled proliferation. The data obtained in this study showed population and morphological stability of major salivary glands after 50 days post-infection by Leishmania (L) infantum chagasi.

Natural transmission of Leishmania infantum through experimentally infected Phlebotomus perniciosus highlights the virulence of Leishmania parasites circulating in the human visceral leishmaniasis outbreak in Madrid, Spain

A human leishmaniasis outbreak is occurring in the Madrid region, Spain, with the parasite and vector involved being Leishmania infantum and Phlebotomus perniciosus respectively. The aim of this study was to investigate the virulence of L. infantum isolates from the focus using a natural transmission model. Hamsters were infected by intraperitoneal inoculation (IP) or by bites of sand flies experimentally infected with L. infantum isolates obtained from P. perniciosus collected in the outbreak area (IPER/ES/2012/BOS1FL1 and IPER/ES/2012/POL2FL6) and a well characterized L. infantum strain JPCM5 (MCAN/ES/98/LLM-877). Hamster infections were monitored by clinical examination, serology, culture, parasite burden, Giemsa-stained imprints, PCR, histopathology and xenodiagnostic studies. Establishment of infection of L. infantum was achieved with the JPCM5 strain and outbreak isolates by both P. perniciosus infective bites or IP route. However, high virulence of BOS1FL1 and POL2FL6 isolates was highlighted by the clinical outcome of disease, high parasite detection in spleen and liver, high parasitic loads and positivity of Leishmania serology. Transmission by bite of POL2FL6 infected flies generated a slower progression of clinical disease than IP infection, but both groups were infective to P. perniciosus by xenodiagnosis at 2 months post-infection. Conversely, hamsters inoculated with JPCM5 were not infective to sand flies. Histopathology studies confirmed the wide spread of POL2FL6 parasites to several organs. A visceral leishmaniasis model that mimics the natural transmission in nature allowed us to highlight the high virulence of isolates that are circulating in the focus. These findings contribute to a better understanding of the outbreak epidemiology.

Large-scale investigation of Leishmania interaction networks with host extracellular matrix by surface plasmon resonance imaging

We have set up an assay to study the interactions of live pathogens with their hosts by using protein and glycosaminoglycan arrays probed by surface plasmon resonance imaging. We have used this assay to characterize the interactions of Leishmania promastigotes with ~70 mammalian host biomolecules (extracellular proteins, glycosaminoglycans, growth factors, cell surface receptors). We have identified, in total, 27 new partners (23 proteins, 4 glycosaminoglycans) of procyclic promastigotes of six Leishmania species and 18 partners (15 proteins, 3 glycosaminoglycans) of three species of stationary-phase promastigotes for all the strains tested. The diversity of the interaction repertoires of Leishmania parasites reflects their dynamic and complex interplay with their mammalian hosts, which depends mostly on the species and strains of Leishmania. Stationary-phase Leishmania parasites target extracellular matrix proteins and glycosaminoglycans, which are highly connected in the extracellular interaction network. Heparin and heparan sulfate bind to most Leishmania strains tested, and 6-O-sulfate groups play a crucial role in these interactions. Numerous Leishmania strains bind to tropoelastin, and some strains are even able to degrade it. Several strains interact with collagen VI, which is expressed by macrophages. Most Leishmania promastigotes interact with several regulators of angiogenesis, including antiangiogenic factors (endostatin, anastellin) and proangiogenic factors (ECM-1, VEGF, and TEM8 [also known as anthrax toxin receptor 1]), which are regulated by hypoxia. Since hypoxia modulates the infection of macrophages by the parasites, these interactions might influence the infection of host cells by Leishmania.