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Zoonotic visceral leishmaniasis : new insights on innate immune response by blood macrophages and liver kupffer cells to leishmania infantum parasites

Publication . Rodrigues, Armanda Viana; Valerio-Bolas, Ana; Alexandre-Pires, Graça; Aires Pereira, Maria; Nunes, Telmo; Ligeiro, Dario; Pereira da Fonseca, Isabel; Santos-Gomes, Gabriela

L. infantum is the aetiological agent of zoonotic visceral leishmaniasis (ZVL), a disease that affects humans and dogs. Leishmania parasites are well adapted to aggressive conditions inside the phagolysosome and can control the immune activation of macrophages (MØs). Although MØs are highly active phagocytic cells with the capacity to destroy pathogens, they additionally comprise the host cells for Leishmania infection, replication, and stable establishment in the mammal host. The present study compares, for the first time, the innate immune response to L. infantum infection of two different macrophage lineages: the blood macrophages and the liver macrophages (Kupffer cells, KC). Our findings showed that L. infantum takes advantage of the natural predisposition of blood-MØs to phagocyte pathogens. However, parasites rapidly subvert the mechanisms of MØs immune activation. On the other hand, KCs, which are primed for immune tolerance, are not extensively activated and can overcome the dormancy induced by the parasite, exhibiting a selection of immune mechanisms, such as extracellular trap formation. Altogether, KCs reveal a different pattern of response in contrast with blood-MØs when confronting L. infantum parasites. In addition, KCs response appears to be more efficient in managing parasite infection, thus contributing to the ability of the liver to naturally restrain Leishmania dissemination

2022-01-09Journal article

Open access

Detection of canine vector-borne diseases agents in Galgo Español used as hunting dogs in Alentejo, Portugal

Publication . Ferreira, Maria Francisca de Sousa Falcão Esteves; Fonseca, Isabel Maria Soares Pereira da

ABSTRACT - Canine Vector-Borne Diseases (CVBD) agents pose a significant risk to both canine and public health, with some of these pathogens having zoonotic potential. Galgo Español dogs in Portugal, particularly those used for hunting hares, are frequently exposed to arthropod vectors of these agents. To assess the rate of infection of CVBD agents in this population, a study was conducted involving collection of blood samples from 34 Galgo Español dogs living in two locations within the Municipality of Évora, Portugal. The sample was composed of 8 male and 26 female dogs, none of them neutered. The diagnostic techniques used were blood smears, modified Knott's technique, immunochromatography and IFAT. A questionnaire was also performed to assess for possible CVBD risk factors in Galgo Español dogs. Results demonstrated a high prevalence of CVBD agents, with seropositivity observed in 33 out of 34 dogs (97.06%), indicating exposure to multiple pathogens. Of the 8 male dogs in this study, all had positive results to at least one test. Regarding females, 25 of 26 had positive results to at least one test. Overall R. conorii was the most seroprevalent pathogen (82% - 28/34), followed by R. rickettsii (79% - 27/34 unexpected result requiring confirmation by molecular techniques), Anaplasma phagocytophilum (68% - 23/34), Babesia canis (44% - 15/34) and Ehrlichia canis (3% - 1/34). Observation of blood smears revealed the prevalence: Babesia spp. (6% - 2/34), Hepatozoon spp. (6% - 2/34), Mycoplasma spp. (3% - 1/34) and Rickettsiales forms (21% - 7/34). No seroprevalence was detected for Leishmania infantum and there were no findings of Dirofilaria immitis antigens or microfilariae. The statistical analysis revealed several significant associations between the collected information on each dog and the outcomes of the diagnostic techniques employed. The risk factors identified in the study include the age of the dogs, the type of housing they reside in, the number of dogs sharing living space, the introduction of new dogs into the pack, the type and frequency of deworming practices and the post-training/hunting care provided. The findings from this study highlight the importance of understanding the rate of infection of CVBD agents and the need for increased awareness and commitment to effective prophylaxis to mitigate the risk of CVBD. Furthermore, there is also the problem of these agents spreading to other animals, including wolves, foxes and even hares in the case of Leishmania. This study has contributed to increasing knowledge of CVBD, promoting a better understanding of the panorama of these diseases in hunting dogs

2024-03-05Master thesis

Open access