The critical role of phosphoenolpyrovate carboxykinase (PEPCK) in immunopathogenesis of cutaneous leishmaniasis
| dc.contributor.author | Feiz Barazandeh, Aida | |
| dc.contributor.examiningcommittee | Soussi Gounni, Abdelilah (Immunology) Ghavami, Saeid (Anatomy and Cell Sciences) | en_US |
| dc.contributor.supervisor | Uzonna, Jude (Immunology) | en_US |
| dc.date.accessioned | 2020-09-10T22:51:04Z | |
| dc.date.available | 2020-09-10T22:51:04Z | |
| dc.date.copyright | 2020-09-10 | |
| dc.date.issued | 2020 | en_US |
| dc.date.submitted | 2020-09-10T17:29:47Z | en_US |
| dc.degree.discipline | Immunology | en_US |
| dc.degree.level | Master of Science (M.Sc.) | en_US |
| dc.description.abstract | Leishmaniasis is a tropical vector-borne infection caused by protozoan Leishmania parasites which are transmitted by the bite of various species of infected female phlebotomine sandflies. This neglected disease with a wide range of clinical symptoms affects 350 million individuals in 88 countries and is considered the second leading cause of mortality after malaria. Cutaneous leishmaniasis is the most common form of the disease caused by several species of parasites. Despite tremendous efforts, no effective vaccine against leishmaniasis that induces a robust and long-lasting immunity yet exists. This could be possibly explained by the lack of sufficient knowledge on Leishmania immunogenic antigens and immunological correlations of protection. We recently found that Leishmania glycosomal phosphoenolpyruvate carboxykinase (PEPCK) is a highly immunogenic antigen that produces a robust T cell-mediated immunity in both mice and human. Remarkably, PEPCK is a gluconeogenic enzyme involved in the conversion of oxaloacetate into phosphoenolpyruvate and is constitutively expressed by both life stages of all pathogenic species of Leishmania parasites. In the current study, I utilized molecular and immunological approaches to investigate the role of PEPCK in virulence and immunopathogenicity of Leishmania major. I successfully generated a PEPCK deficient L. major and demonstrated that the targeted loss of PEPCK results in a compromised growth in axenic cultures once glucose is depleted from media. Although the selective loss of PEPCK does not influence metacyclogenesis, the PEPCK deficient parasites exhibit a severely impaired proliferation in bone marrow-derived macrophages. Moreover, the absence of PEPCK leads to an attenuated pathology in vivo. Indeed, PEPCK null mutants permanently fail to induce cutaneous lesions in highly susceptible BALB/c mice infected with these parasites despite the persistence of a low number of parasites at the site of infection in these mice. Furthermore, the ablation of PEPCK, as an immunogenic antigen, leads to a reduction in the frequency of cytokine (IFN-, IL-4, and IL-10) -producing CD4+ T cells, and consequently blunted immune response in susceptible mice. Surprisingly, vaccination with PEPCK deficient L. major confers moderate protection (minor DTH response and low level of IFN-) against secondary virulent challenge in BALB/c mice which is not associated with a strong in vitro recall response. Lastly, I reported here that PEPCK deficient parasites exhibit markedly higher extracellular acidification rate, enhanced oxygen consumption rate and proton leak, and reduced ATP coupling efficiency compared to wild type and addback counterparts. Collectively, these findings indicate that PEPCK is a key metabolic enzyme and its targeted loss leads to an attenuated phenotype in vitro (axenic culture and bone marrow-derived macrophages) and in vivo (susceptible mice), altered metabolic activity, and blunted host immune response. | en_US |
| dc.description.note | October 2020 | en_US |
| dc.identifier.uri | http://hdl.handle.net/1993/35040 | |
| dc.language.iso | eng | en_US |
| dc.rights | open access | en_US |
| dc.subject | cutaneous leishmaniasis, Leishmania major, metabolism, PEPCK, imminodominant, metabolism, infection, host Immune resposne | en_US |
| dc.title | The critical role of phosphoenolpyrovate carboxykinase (PEPCK) in immunopathogenesis of cutaneous leishmaniasis | en_US |
| dc.type | master thesis | en_US |