Exploring the mechanisms of action of the antimicrobial peptide CZS-5 against Trypanosoma cruzi epimastigotes: insights from metabolomics and molecular dynamics.

Abstract

Background: Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, is a neglected tropical illness affecting an estimated 6-7 million people worldwide. The currently approved drugs have significant limitations, but antimicrobial peptides (AMPs) have emerged as promising therapeutic alternatives. Members of the cruzioseptin family, a group of AMPs derived from the frog Cruziohyla calcarifer, have demonstrated anti-T. cruzi activity, but their mode of action remains poorly understood. Herein, T. cruzi epimastigotes were used to identify active cruzioseptins and investigate their mechanism of action through untargeted metabolomics and molecular dynamics simulations.

Methods: Synthetic versions of three previously unstudied cruzioseptins (CZS-5, CZS-7, and CZS-11) were evaluated for their effects on T. cruzi X-1081 epimastigotes via microplate assays with resazurin-based viability measurements. CZS-1, a peptide with known anti-T. cruzi activity, was also included. Selectivity was assessed via hemolysis assays on human erythrocytes. To evaluate membrane damage, DNA leakage assays and scanning electron microscopy (SEM) were performed on epimastigotes treated with CZS-5. In addition, the interaction of cruzioseptins with the epimastigote membrane was modeled using molecular dynamics simulations. To explore additional mechanisms of action, a multiplatform metabolomic analysis (HILIC-LC-QTOF-MS and GC-QTOF-MS) was conducted to identify altered metabolites in epimastigotes treated with CZS-5.

Results: Among the tested cruzioseptins, CZS-5 exhibited the highest potency (IC₅₀ = 4.7 ± 1.0 µM) and selectivity (SI = 50.3). This peptide induced DNA leakage from epimastigotes and caused surface alterations, suggesting membrane damage. Molecular dynamics simulations indicated that CZS-5 may exert its effects through the formation of toroidal pores in the parasite membrane. Untargeted metabolomic analysis revealed 118 altered metabolites in CZS-5-treated epimastigotes, with significant enrichment of glycerophospholipids (40.7%), supporting the involvement of membrane disruption. In addition, metabolic pathways were affected, suggesting complementary mechanisms of action, including oxidative stress and disruptions in energy metabolism.

Conclusions: CZS-5 was identified as a potent cruzioseptin with multiple potential mechanisms of action in the epimastigotes stage of T. cruzi. Further validation is needed in clinically relevant parasite stages to assess its potential as a therapeutic agent.