Acquired Tolerance to Ivermectin and Moxidectin after Drug Selection Pressure in the Nematode Caenorhabditis elegans

Abstract

cIvermectin and moxidectin are the most widely administered anthelmintic macrocyclic lactones (MLs) to treat human and animal nematode infections. Their widespread and frequent use has led to a high level of resistance to these drugs. Although they have the same mode of action, differences in terms of selection for drug resistance have been reported. Our objective was to study and compare changes occurring upon ivermectin or moxidectin selection in the model nematode Caenorhabditis elegans. C. elegans worms were submitted to stepwise exposure to increasing doses of moxidectin. The sensitivity of moxidectin-selected worms to MLs was determined in a larval development assay and compared with those of wild-type and ivermectin-selected strains. Selection with either ivermectin or moxidectin led to acquired tolerance to ivermectin, moxidectin, and eprinomectin. Importantly, moxidectin was the most potent ML in both ivermectin-and moxidectin-selected strains. Interestingly, this order of potency was also observed in a resistant Haemonchus contortus isolate. In addition, ivermectin-and moxidectin-selected strains displayed constitutive overexpression of several genes involved in xenobiotic metabolism and transport. Moreover, verapamil potentiated sensitivity to ivermectin and moxidectin, demonstrating that ABC transporters play a role in ML sensitivity in ML-selected C. elegans strains. Finally, both ivermectin-and moxidectin-selected strains displayed a dye-filling-defective phenotype. Overall, this work demonstrated that selection with ivermectin or moxidectin led to cross-resistance to several MLs in nematodes and that the induction of detoxification systems and defects in the integrity of amphidial neurons are two mechanisms that appear to affect the responsiveness of worms to both ivermectin and moxidectin.T he broad-spectrum anthelmintic macrocyclic lactones (MLs) are most commonly used in veterinary medicine to treat diseases caused by gastrointestinal nematodes and external parasites in livestock (1, 2). Ivermectin (IVM) was the first ML approved for use in animals and remains today the sole ML registered for use in humans, mainly to treat onchocerciasis through mass chemotherapy. Another ML, moxidectin (MOX), was subsequently commercialized for the veterinary market and is currently being evaluated for possible use against human onchocerciasis (3). Inevitably, the intensive use of these compounds has led to the emergence of resistance in small ruminant, cattle, and some human nematode parasites (4-7). Discovering the mechanisms by which resistance to MLs occurs remains an important challenge today.There is consistent evidence that ATP-binding-cassette (ABC) transporters such as P-glycoproteins (Pgps) play an important role in multidrug resistance (MDR) in many organisms, including several nematode species. Gene expression levels of ABC transporters or allele frequencies were modified after ML selection (8-13), and they are involved in the tolerance of Caenorhabditis elegans (9, 14-16) and parasitic nematodes s...

A Whole Genome Re-Sequencing Based GWA Analysis Reveals Candidate Genes Associated with Ivermectin Resistance in Haemonchus contortus

“…Given the high level of genetic diversity, H. contortus may provide the fertile grounds for drug selection. Exposure to low levels of IVM may lead to the rapid selection and acquired tolerance against it in H. contortus [77]. None of the previously proposed candidate genes for IVM resistance was found in the two backcross experiments [32,40].…”

In silico analysis of the binding of anthelmintics to Caenorhabditis elegans P-glycoprotein 1

“…There is little information on their functions, except that the loss of each of the 14 Pgps increases susceptibility of C. elegans to IVM to various degrees (Ardelli and Prichard, 2013, Janssen et al., 2013). Also, induction of expression of some Pgp genes after selection under IVM pressure is associated with IVM resistance in C. elegans and in several parasitic nematodes, which can be partly reversed by using mammalian Pgp inhibitors (James and Davey, 2009, Lespine et al., 2012, Menez et al., 2016). In addition, ML were shown to inhibit parasitic nematode Pgp-mediated drug transport in heterologous recombinant systems overexpressing Hco-Pgp-2, Hco-Pgp-9.1, Hco-Pgp-16, Cylicocylus elongatus ( Ceg )-Pgp-9 or Dirofilaria immitis ( Dim) -Pgp-11 (Godoy et al., 2015a, Godoy et al., 2015b, Godoy et al., 2016, Kaschny et al., 2015, Mani et al., 2016).…”

<i>In vitro</i> study of the anthelmintic activity of aqueous and methanol extract of <i>Guiera senegalensis</i> against egg hatch and larval developmental of <i>Caenorhabditis elegans</i>

“…Therefore, it is reasonably assumed that drug effects on might be reproduced on any member trichostrongylidae (Katiki et al, 2011, Kumarasingha et al, 2014. For instance, Moxidectin confirmed as a potent drug against the wild type and ivermectin resistant strain of C. elegans was equally confirmed to be effective against ivermectin resistant (Ménez et al, 2016). Guiera senegalensis is among other traditional herbal medicines been used in the treatment of ailment, with no proper scientific validation and documentation.…”