Paromomycin II

Cutaneous leishmaniosis (CL) is treated with pentavalent antimony (SbV) as a first-line drug, while amphotericin B and paromomycin are potential alternatives in antimonial- resistant isolates. However, the mechanisms of drug resistance remain unclear. The present study analyses the gene expression of RNA polymerase II (RNAP II) and J-binding protein 1 (JBP1), and J-binding protein 2 (JBP2) in Leishmania major after exposure to drugs in vitro. L. major (MRHO/IR/75/ER) promastigotes were exposed to various concentrations of glucantime, paromomycin and amphotericin B for 72 hours. The RNA was then extracted and used for cDNA synthesis. The expressions of JBP1, JBP2 and RNAP II were analysed using SYBR Green real-time PCR. No change in JBP2 or RNAP II expression was associated with amphotericin B, but JBP1 expression decreased with increasing drug concentration. Paromomycin had no effect on JBP2 expression, but a 13.5-fold increase in JBP1 was observed at 100 μg/ml, and a decrease in RNAP II expression at 25 and 50 μg/ml. Exposure to glucantime resulted in 1.4-fold lower JBP1 expression at 5 μg/ml, and 333.33- to 500-fold lower RNAP II at concentrations of 5 to 15 μg/ml. As Base J synthesis requires both JBP1 and JBP2, RNAP II (encoding RNA polymerase II) could reduce expression. However, RNAP II was not expressed in all groups, indicating that the genes associated with drug resistance may be regulated in other ways.

Novel amphiphilic aminoglycosides are shown to inhibit clinically relevant deactivating enzymes, without undergoing significant deactivation themselves.

Objectives: To evaluate the in vitro activity of antileishmanial drugs, paromomycin and miltefosine, to generate Th-1-biased immunomodulation in hosts against intracellular Leishmania donovani. Methods: In silico protein-ligand interaction and in vitro drug-cell interaction assays were performed. Interaction assays of TLR4-deficient HEK293 cells and HEK293 cells engineered to express either TLR4 or TLR2 with different concentrations of miltefosine and/or paromomycin sulphate were performed for 48 h. Differentially transfected human peripheral blood monocyte-derived macrophages (PBMFs) were treated with the drugs, and nuclear factor (NF)-κB promoter activity was measured using a κB-luciferase reporter construct. PBMFs were infected with L. donovani. Cultures were incubated with miltefosine or paromomycin sulphate over different concentrations, as mono-treatment or combined. The in vitro antileishmanial effect of the drugs on macrophage-bound L. donovani amastigotes was measured in terms of parasite killing and production of tumour necrosis factor-α (TNF-α) and nitric oxide. Results: Computational studies reveal that paromomycin and miltefosine interact with TLR4. Both drugs, as monotherapy or in combination, induce release of TNF-α and nitric oxide in a TLR4-dependent manner. Interestingly, the TLR4-dependent action of the drugs leads to NF-κB promoter activation through MyD88. In vitro, both the drugs kill macrophage-bound L. donovani by inducing release of TNF-α and nitric oxide in a TLR4-dependent manner. Conclusions: The in vitro activity of paromomycin and miltefosine against host cells is TLR4 dependent. This has implications for: (i) evaluation of in vitro activity of combinational antileishmanial therapy; (ii) the evaluation of drug susceptibility of clinical isolates; and (iii) the standardization of in vitro antileishmanial assays for determining toxicity in hosts.