Investigation of the pathways related to intrinsic miltefosine tolerance in Leishmania (Viannia) braziliensis clinical isolates reveals differences in drug uptake

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Espada, Caroline R. ; Magalhaes, Rubens M. ; Cruz, Mario C. ; Machado, Paulo R. ; Schriefer, Albert ; Carvalho, Edgar M. ; Hornillos, Valentin ; Alves, Joao M. ; Cruz, Angela K. ; Coelho, Adriano C. ; Uliana, Silvia R. B.

• Document type: Journal article
• Source: INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE; v. 11, p. 9-pg., 2019-12-01.

Abstract

In Brazil, cutaneous leishmaniasis is caused predominantly by L. (V.) braziliensis. The few therapeutic drugs available exhibit several limitations, mainly related to drug toxicity and reduced efficacy in some regions. Miltefosine (MF), the only oral drug available for leishmaniasis treatment, is not widely available and has not yet been approved for human use in Brazil. Our group previously reported the existence of differential susceptibility among L. (V.) braziliensis clinical isolates. In this work, we further characterized three of these isolates of L. (V.) braziliensis chosen because they exhibited the lowest and the highest MF half maximal inhibitory concentrations and were therefore considered less tolerant or more tolerant, respectively. Uptake of MF, and also of phosphocholine, were found to be significantly different in more tolerant parasites compared to the less sensitive isolate, which raised the hypothesis of differences in the MF transport complex Miltefosine Transporter (MT)Ros3. Although some polymorphisms in those genes were found, they did not correlate with the drug susceptibility phenotype. Drug efflux and compartmentalization were similar in the isolates tested, and amphotericin B susceptibility was retained in MF tolerant parasites, suggesting that increased fitness was also not the basis of observed differences. Transcriptomic analysis revealed that Ros3 mRNA levels were upregulated in the sensitive strain compared to the tolerant ones. Increased mRNA abundance in more tolerant isolates was validated by quantitative PCR. Our results suggest that differential gene expression of the MT transporter complex is the basis of the differential susceptibility in these unelected, naturally occurring parasites. (AU)

• FAPESP's process: 12/14629-5 - Mechanisms of action and resistance to miltefosine in Leishmania spp.
• Grantee: Adriano Cappellazzo Coelho
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 15/09080-2 - Evaluation of candidate drugs for the treatment of Leishmaniasis in Brazil
• Grantee: Silvia Reni Bortolin Uliana
• Support Opportunities: Regular Research Grants
• FAPESP's process: 11/20484-7 - Tamoxifen in the treatment of leishmaniasis: evaluation of efficacy in combination therapy schemes and study of the antileishmanial mechanism of action
• Grantee: Silvia Reni Bortolin Uliana
• Support Opportunities: Regular Research Grants
• FAPESP's process: 16/23405-4 - Susceptibility to miltefosine in Leishmania (Viannia) braziliensis clinical isolates: phenotypic characterization and investigation of the basis involved in reduced susceptibility to the drug
• Grantee: Caroline Ricce Espada
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)