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Full text release has been delayed at the author's request until May 10, 2027

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Uncovering Novel Immuno-metabolic Profiles in Cutaneous Leishmaniasis: From Vaccine Development to Analgesic Mechanisms

Volpedo, Greta
http://orcid.org/0000-0002-1112-7715
http://rave.ohiolink.edu/etdc/view?acc_num=osu1648831730997539

Abstract Details

2022, Doctor of Philosophy, Ohio State University, 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 taurine/hypotaurine metabolism in their ears, and linoleic acid in their lymph nodes, important to enhance macrophage and T cell responses against Leishmania. Uncovering the unique metabolic signatures of vaccination and disease is invaluable to identify novel markers of vaccine efficacy and understand the correlates of protective immunity. Metabolomics can also be used to investigate interesting physiological phenomena in CL and identify the molecular mechanisms responsible. In particular, CL is known to cause painless lesions, indicating that Leishmania infection modulates pain signals within the infected area. Through mass spectrometry analysis, we found elevated levels of caffeine metabolites in L. mexicana-infected compared to uninfected macrophages. Similar results were obtained at the lesion site during chronic infection. These caffeine metabolites are anti-inflammatory and display analgesic properties. Furthermore, we found enriched arachidonic acid (AA) metabolism during infection in vivo. AA is a metabolite of endocannabinoids, well established anti-inflammatory and analgesic mediators. We also observed significantly higher transcript levels of enzymes involved in endocannabinoid biosynthesis, and significantly lower expression of enzymes important for their degradation in infected mice. This study provides the first evidence of metabolic pathways with a potential molecular basis for the analgesia experienced by CL patients. Overall, furthering our understanding of leishmaniasis, as well as the metabolic and immunological changes that affect resistance and susceptibility, can have broad implications for the development of novel preventive and therapeutic strategies to fill a worldwide critical need.
Abhay Satoskar (Advisor)
Pravin Kaumaya (Committee Member)
Steve Oghumu (Committee Member)
Jesse Kwiek (Committee Member)
181 p.
Immunology; Microbiology; Neurosciences; Parasitology
Cutaneous leishmaniasis; Leishmania mexicana; live-attenuated vaccine; CRISPR/Cas9; centrin; growth defect; immunogenicity; efficacy; metabolic reprogramming; pentose phosphate pathway; painless lesions; caffeine metabolism; arachidonic acid metabolism; endocannabinoids

Recommended Citations

Citations

  • Volpedo, G. (2022). Uncovering Novel Immuno-metabolic Profiles in Cutaneous Leishmaniasis: From Vaccine Development to Analgesic Mechanisms [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1648831730997539

    APA Style (7th edition)

  • Volpedo, Greta. Uncovering Novel Immuno-metabolic Profiles in Cutaneous Leishmaniasis: From Vaccine Development to Analgesic Mechanisms. 2022. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1648831730997539.

    MLA Style (8th edition)

  • Volpedo, Greta. "Uncovering Novel Immuno-metabolic Profiles in Cutaneous Leishmaniasis: From Vaccine Development to Analgesic Mechanisms." Doctoral dissertation, Ohio State University, 2022. http://rave.ohiolink.edu/etdc/view?acc_num=osu1648831730997539

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.