Oral immunization with heat-inactivated Mycobacterium bovis reduces local parasite dissemination and hepatic granuloma development in mice infected with Leishmania amazonensis

• Published in: Research in veterinary science Vol. 162; p. 104963
• Main Authors: Ferreras-Colino, Elisa, Moreno, Inmaculada, Gortázar, Christian, Sevilla, Iker, Agulló-Ros, Irene, Domínguez, Lucas, Juste, Ramón, Risalde, Maria A., Domínguez, Mercedes
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.09.2023
• Subjects: Animals; Female; Granuloma - veterinary; Heat-inactivated Mycobacterium bovis; Hepatitis; Hot Temperature; Immunization - veterinary; Leishmania; Leishmania mexicana; Liver; Macrophages; Mice; Mice, Inbred BALB C; Mycobacterium bovis; Parasites; Trained immunity; Trained immunity; Macrophages; Heat-inactivated Mycobacterium bovis; Leishmania; Liver
• ISSN: 0034-5288; 1532-2661
• DOI: 10.1016/j.rvsc.2023.104963

Aiming to explore whether oral immunization with heat-inactivated Mycobacterium bovis (HIMB) protects mice against Leishmania infection, 18 female BALB/c mice were randomly assigned to the immunized group, that received oral HIMB, or the control group, and were infected by inoculation of 10,000 Leishmania amazonensis promastigotes in the footpad. Spleen culture was positive in 55.55% of immunized mice and in 100% of control mice (p = 0.082). The number of immunolabeled amastigotes number in the popliteal lymph node was lower in the immunized group (p = 0.009). The immunized group presented fewer mature granulomas in the liver (p = 0.005) and more Lys + macrophages (p = 0.002) and fewer CD3+ T lymphocytes (p < 0.001) per hepatic granuloma. We conclude that immunization with HIMB via the oral route limited local parasite dissemination and hepatic granuloma development in mice challenged with Leishmania amazonensis through stimulation of macrophages, which is compatible with trained immunity. •Heat-inactivated Mycobacterium bovis impairs local dissemination of Leishmania.•Heat-inactivated Mycobacterium bovis slows liver granuloma progression.•Heat-inactivated Mycobacterium bovis stimulates macrophages response.