Doctor of Philosophy, The Ohio State University, 2022, Microbiology
Leishmaniasis is a neglected protozoan disease affecting over 12 million people globally. Cutaneous leishmaniasis (CL) is the most common form, characterized by chronic skin lesions. Currently, there are no approved vaccines for human use. We have generated centrin knock out Leishmania (L.) mexicana (LmexCen-/-) mutants using CRISPR/Cas9. Centrin is a cytoskeletal protein required only for intracellular amastigote replication in Leishmania. Here, we investigated the safety, immunogenicity, and efficacy of LmexCen-/- parasites in vitro and in vivo. Our data shows that LmexCen-/- amastigotes present a growth defect, which results in significantly lower parasitic burdens and increased protective cytokine production in infected macrophages and dendritic cells,
compared to LmexWT. Furthermore, LmexCen-/- parasites are safe in susceptible mouse models and efficacious against challenge with LmexWT in genetically different BALB/c and C57BL/6 mice. Vaccinated mice did not develop cutaneous lesions, displayed protective immunity, and showed significantly lower parasitic burdens compared to the controls. Overall, we demonstrate that LmexCen-/- parasites are a promising candidate vaccine against CL in pre-clinical models.
Next, we explored the metabolic drivers of these vaccine-mediated immunological profiles. Metabolomics are emerging as a useful tool to uncover unknown networks that govern immune regulation and determine functional specialization. We analyzed the metabolic changes occurring after immunization with LmexCen-/- and compared them with LmexWT infection. Our results show enriched aspartate metabolism and pentose phosphate pathway (PPP) in ears immunized with LmexCen-/- parasites. These pathways are both known to promote M1 polarization in macrophages, and PPP in particular induces nitric oxide production in macrophages cultured with LmexCen-/-, suggesting a shift to a pro-inflammatory phenotype following immunization. Furthermore, immunized mice showed enriched t (open full item for complete abstract)
Committee: Abhay Satoskar (Advisor); Pravin Kaumaya (Committee Member); Steve Oghumu (Committee Member); Jesse Kwiek (Committee Member)
Subjects: Immunology; Microbiology; Neurosciences; Parasitology