Novel Therapeutic Approaches for Trypanosoma cruzi Infection
Trypanosoma cruzi (T. cruzi) is the causative agent of Chagas disease (ChD), an emerging illness prevalent in South and Central America. Presently, benznidazole and nifurtimox are the only two clinically available drugs against T. cruzi, which have high toxicity and limited efficacy in the chronic phase of the disease. This ailment affects 8-10 million people and has become an emerging concern in the U.S leading to an urgent need for the discovery of new treatments. Despite all efforts, there is no human vaccine available. Therapeutic vaccines are a possible option for chronic ChD in which the vaccine is used after infection, by inducing anti-trypanocidal immunity. MASPpep is a synthetic 20-mer peptide (DAENPGGEVFNDNKKGLSRV) which is a derivative of T. cruzi mucin associated surface protein (MASP) that has been previously investigated as a prophylactic vaccine. This study demonstrated that MASPpep conjugated to keyhole limpet hemocyanin (MASPpep-KLH) elicited a protective Th1 and Th17 immune response and lytic antibody production against T. cruzi challenged mice. For this reason, using a therapeutic vaccine in combination with benznidazole is an approach that is currently under investigation. Here, we investigate immunochemotherapeutic strategies utilizing peptide vaccine to alter the immune response by combining conserved MASPpep-KLH antigen in combination with benznidazole to achieve complete parasitic clearance. Considering the limited efficacy of benznidazole in the chronic phase of ChD, another approach is to validate N-myristoyltransferase inhibitors as chemotherapeutic agents. N-myristoyltransferase (NMT) is an enzyme that catalyzes the transfer of myristoyl-CoA into proteins. Myristoylated proteins are involved in regulating various cellular functions in eukaryotes. This pervasive modification has shown to be crucial for protein localization and function of protozoan parasites such as T. cruzi, and Trypanosoma brucei (T. brucei). Over one hundred myristoylated proteins have been identified in T. cruzi, predicting that inhibition of NMT will have pleiotropic effects. Additionally, NMT is expressed in all stages of the parasite. Thus, encouraging NMT inhibitors as valid drug candidates for the treatment of T. cruzi, which have been previously evaluated against T. brucei NMT. Respectively, selective NMT inhibitors DDD1 and DDD5 presented high trypanocidal activity with an EC50 of 0.18 µM and 0.26 µM in intracellular forms of T. cruzi with minimal cytotoxicity. Consequently, anti-trypanocidal activity of NMT inhibitors DDD86481 (DDD1) and DDD100097 (DDD5) were screened in an in vivo murine model for chronic ChD. Compounds DDD1 and DDD5 significantly reduced parasite load in the murine chronic model without permissible toxicity. Fundamentally, this immunochemotherapeutic approach is to attain clearance and protection via treatment with NMT inhibitors while producing a humoral and cellular immune response by MASPpep-KLH in a mouse model of chronic T. cruzi infection.
Torres, Caresse Lynn, "Novel Therapeutic Approaches for Trypanosoma cruzi Infection" (2018). ETD Collection for University of Texas, El Paso. AAI10823092.