AUTHOR=Silva M. , Malmberg M. , Otienoburu S. D. , Björkman A. , Ngasala B. , Mårtensson A. , Gil J. P. , Veiga M. I. 

TITLE=Plasmodium falciparum Drug Resistance Genes pfmdr1 and pfcrt In Vivo Co-Expression During Artemether-Lumefantrine Therapy

JOURNAL=Frontiers in Pharmacology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2022.868723

DOI=10.3389/fphar.2022.868723

ISSN=1663-9812

ABSTRACT=<p><bold>Background:</bold> Artemisinin-based combination therapies (ACTs) are the global mainstay treatment of uncomplicated <italic>Plasmodium falciparum</italic> infections. <italic>Pf</italic>MDR1 and <italic>Pf</italic>CRT are two transmembrane transporters, associated with sensitivity to several antimalarials, found in the parasite food vacuole. Herein, we explore if their relatedness extends to overlapping patterns of gene transcriptional activity before and during ACT administration.</p><p><bold>Methods:</bold> In a clinical trial performed in Tanzania, we explored the <italic>pfmdr1</italic> and <italic>pfcrt</italic> transcription levels from 48 patients with uncomplicated <italic>P. falciparum</italic> malaria infections who underwent treatment with artemether-lumefantrine (AL). Samples analyzed were collected before treatment initiation and during the first 24 h of treatment. The frequency of <italic>Pf</italic>MDR1 N86Y and <italic>Pf</italic>CRT K76T was determined through PCR-RFLP or direct amplicon sequencing. Gene expression was analyzed by real-time quantitative PCR<italic>.</italic></p><p><bold>Results:</bold> A wide range of pre-treatment expression levels was observed for both genes, approximately 10-fold for <italic>pfcrt</italic> and 50-fold for <italic>pfmdr1.</italic> In addition, a significant positive correlation demonstrates <italic>pfmdr1</italic> and <italic>pfcrt</italic> co-expression. After AL treatment initiation, <italic>pfmdr1</italic> and <italic>pfcrt</italic> maintained the positive co-expression correlation, with mild downregulation throughout the 24 h post-treatment. Additionally, a trend was observed for <italic>Pf</italic>MDR1 N86 alleles and higher expression before treatment initiation.</p><p><bold>Conclusion:</bold><italic>pfmdr1</italic> and <italic>pfcrt</italic> showed significant co-expression patterns <italic>in vivo</italic>, which were generally maintained during ACT treatment. This observation points to relevant related roles in the normal parasite physiology, which seem essential to be maintained when the parasite is exposed to drug stress. In addition, keeping the simultaneous expression of both transporters might be advantageous for responding to the drug action.</p>