Sub-lethal doses of albendazole induce drug metabolizing enzymes and increase albendazole deactivation in Haemonchus contortus adults.

The efficacy of anthelmintic therapy of farm animals rapidly decreases due to drug resistance development in helminths. In resistant isolates, the increased expression and activity of drug-metabolizing enzymes (DMEs), e.g. cytochromes P450 (CYPs), UDP-glycosyltransferases (UGTs) and P-glycoprotein transporters (P-gps), in comparison to sensitive isolates have been described. However, the mechanisms and circumstances of DMEs induction are not well known. Therefore, the present study was designed to find the changes in expression of CYPs, UGTs and P-gps in adult parasitic nematodes Haemonchus contortus exposed to sub-lethal doses of the benzimidazole anthelmintic drug albendazole (ABZ) and its active metabolite ABZ-sulfoxide (ABZSO). In addition, the effect of ABZ at sub-lethal doses on the ability to deactivate ABZ during consequent treatment was studied. The results showed that contact of H. contortus adults with sub-lethal doses of ABZ and ABZSO led to a significant induction of several DMEs, particularly cyp-2, cyp-3, cyp-6, cyp-7, cyp-8, UGT10B1, UGT24C1, UGT26A2, UGT365A1, UGT366C1, UGT368B2, UGT367A1, UGT371A1, UGT372A1 and pgp-3, pgp-9.1, pgp-9.2, pgp-10. This induction led to increased formation of ABZ metabolites (especially glycosides) and their increased export from the helminths' body into the medium. The present study demonstrates for the first time that contact of H. contortus with sub-lethal doses of ABZ (e.g. during underdose treatment) improves the ability of H. contortus adults to deactivate ABZ in consequent therapy.

Investigation of the Secretory Pathway in Trichomonas vaginalis Argues against a Moonlighting Function of Hydrogenosomal Enzymes.

The enzymes pyruvate ferredoxin oxidoreductase (PFO), malic enzyme (ME), and the α- and ß-subunits of succinyl-CoA synthetase (SCS) catalyze key steps of energy metabolism in Trichomonas vaginalis hydrogenosomes. These proteins have also been characterized as the adhesins AP120 (PFO), AP65 (ME), AP33, and AP51 (α- and ß-SCS), which are localized on the cell surface and mediate the T. vaginalis cytoadherence. However, the mechanisms that facilitate the targeting of these proteins to the cell surface via the secretory pathway and/or to hydrogenosomes are not known. Here we adapted an in vivo biotinylation system to perform highly sensitive tracing of protein trafficking in T. vaginalis. We showed that α- and ß-SCS are biotinylated in the cytosol and imported exclusively into the hydrogenosomes. Neither α- nor ß-SCS is biotinylated in the endoplasmic reticulum and delivered to the cell surface via the secretory pathway. In contrast, two surface proteins, tetratricopeptide domain-containing membrane-associated protein and tetraspanin family surface protein, as well as soluble-secreted ß-amylase-1 are biotinylated in the endoplasmic reticulum and delivered through the secretory pathway to their final destinations. Taken together, these results demonstrate that the α- and ß-SCS subunits are targeted only to the hydrogenosomes, which argues against their putative moonlighting function.

The induction and inhibition of UDP-glycosyltransferases in Haemonchus contortus and their role in the metabolism of albendazole.

Albendazole (ABZ) is an anthelmintic frequently used to treat haemonchosis, a common parasitosis of ruminants caused by the gastrointestinal nematode Haemonchus contortus. This parasite is able to protect itself against ABZ via the formation of inactive ABZ-glycosides. The present study was designed to deepen the knowledge about the role of UDP-glycosyltransferases (UGTs) in ABZ glycosylation in H. contortus. The induction effect of phenobarbital, a classical inducer of UGTs, as well as ABZ and ABZ-sulphoxide (ABZSO, the main active metabolite of ABZ) on UGTs expression and UGT activity toward ABZ was studied ex vivo in isolated adult nematodes. The effect of three potential UGT inhibitors (5-nitrouracil, 4,6-dihydroxy-5-nitropyrimidine and sulfinpyrazone) on ABZ glycosylation was tested. Pre-incubation of nematodes with ABZ and ABZSO led to increased expression of several UGTs as well as ABZ-glycosides formation in subsequent treatment. Phenobarbital also induced UGTs expression, but did not affect ABZ biotransformation. In the nematode's subcellular fraction, sulfinpyrazone inhibited UGT activity toward ABZ, although no effect of other inhibitors was observed. The inhibitory potential of sulfinpyrazone on the formation of ABZ-glycosides was also proved ex vivo in living nematodes. The obtained results confirmed the role of UGTs in ABZ biotransformation in H. contortus adults and revealed sulfinpyrazone as a potent inhibitor of ABZ glycosylation in this parasite. The possible use of sulfinpyrazone with ABZ in combination therapy merits further research.

UDP-Glycosyltransferases and Albendazole Metabolism in the Juvenile Stages of Haemonchus contortus.

The nematode Haemonchus contortus, a gastrointestinal parasite of ruminants, can severely burden livestock production. Although anthelmintics are the mainstay in the treatment of haemonchosis, their efficacy diminishes due to drug-resistance development in H. contortus. An increased anthelmintics inactivation via biotransformation belongs to a significant drug-resistance mechanism in H. contortus. UDP-glycosyltransferases (UGTs) participate in the metabolic inactivation of anthelmintics and other xenobiotic substrates through their conjugation with activated sugar, which drives the elimination of the xenobiotics due to enhanced solubility. The UGTs family, in terms of the biotransformation of commonly used anthelmintics, has been well described in adults as a target stage. In contrast, the free-living juvenile stages of H. contortus have attracted less attention. The expression of UGTs considerably varies throughout the life cycle of the juvenile nematodes, suggesting their different roles. Furthermore, the constitutive expression in a susceptible strain with two resistant strains shows several resistance-related changes in UGTs expression, and the exposure of juvenile stages of H. contortus to albendazole (ABZ) and ABZ-sulfoxide (ABZSO; in sublethal concentrations) leads to the increased expression of several UGTs. The anthelmintic drug ABZ and its primary metabolite ABZSO biotransformation, tested in the juvenile stages, shows significant differences between susceptible and resistant strain. Moreover, higher amounts of glycosidated metabolites of ABZ are formed in the resistant strain. Our results show similarly, as in adults, the UGTs and glycosidations significant for resistance-related differences in ABZ biotransformation and warrant further investigation in their individual functions.

Ivermectin-induced changes in the expression of cytochromes P450 and efflux transporters in Haemonchus contortus female and male adults.

Haemonchus contortus, one of the most pathogenic of all small ruminant parasites, have developed resistance to all used anthelmintics. Detoxification enzymes, e.g. cytochromes P450 (CYPs) and efflux transporters P-glycoproteins (P-gps), which represent the main defense system against harmful xenobiotics, have been suggested to contribute to drug resistance development. The present study was designed to compare the constitutive expression of individual CYPs and P-gps in females and males of H. contortus adults and to follow up on the changes in expression of these genes in nematodes exposed to sub-lethal concentrations of ivermectin (IVM), which might occur during inaccurate treatment. The adults of inbred susceptible-Edinburgh strain (ISE, MHco3) of H. contortus were used for this purpose. The nematodes were incubated ex vivo with or without IVM (1, 10 and 100 nM) in culture medium for 4, 12 and 24 h. After incubation, total RNA was isolated and expression levels of individual CYPs and P-gps were analyzed using qPCR. Our results showed a great variability in the constitutive expression of individual CYPs and P-gps in H. contortus adults. The constitutive expression as well as the inducibility of CYPs and P-gps significantly differed in males and females. Contact of adult nematodes with sub-lethal IVM concentrations led to only minor changes in expression of CYPs, while expression of several P-gps, particularly pgp-9.2 in males and pgp-10, pgp-11 in females was increased significantly in IVM-exposed nematodes. In conclusion, inaccurate treatment of sheep with IVM might contribute to drug resistance development via increased expression of efflux transporters in H. contortus adults.

UDP-glycosyltransferase family in Haemonchus contortus: Phylogenetic analysis, constitutive expression, sex-differences and resistance-related differences.

UDP-glycosyltransferases (UGT), catalysing conjugation of UDP-activated sugar donors to small lipophilic chemicals, are widespread in living organisms from bacteria to fungi, plant, or animals. The progress of genome sequencing has enabled an assessment of the UGT multigene family in Haemonchus contortus (family Trichostrongylidae, Nematoda), a hematophagous gastrointestinal parasite of small ruminants. Here we report 32 putative UGT genes divided into 15 UGT families. Phylogenetic analysis in comparison with UGTs from Caenorhabditis elegans, a free-living model nematode, revealed several single member homologues, a lack of the dramatic gene expansion seen in C. elegans, but also several families (UGT365, UGT366, UGT368) expanded in H. contortus only. The assessment of constitutive UGT mRNA expression in H. contortus adults identified significant differences between females and males. In addition, we compared the expression of selected UGTs in the drug-sensitive ISE strain to two benzimidazole-resistant strains, IRE and WR, with different genetic backgrounds. Constitutive expression of UGT368B2 was significantly higher in both resistant strains than in the sensitive strain. As resistant strains were able to deactivate benzimidazole anthelmintics via glycosylation more effectively then the sensitive strain, UGT368B2 enhanced constitutive expression might contribute to drug resistance in H. contortus.

Zoonotic Trichomonas tenax and a new trichomonad species, Trichomonas brixi n. sp., from the oral cavities of dogs and cats.

Trichomonads are known to inhabit the oral cavities of various mammals, including dogs, cats and horses. However, little attention has been paid to species identification, prevalence and zoonotic potential of these parasites, although their hosts live in close proximity with humans. According to the original description, oral trichomonads in dogs and cats belong to the genus Tetratrichomonas. Interestingly, later investigations suggested that the oral cavities of dogs and cats could be infected with different species of the genus Trichomonas, including the human oral cavity parasite Trichomonas tenax. Thus, in this study we investigated the occurrence of oral trichomonads in 111 domestic dogs and 122 cats using cell cultivation methods, nested PCR analyses, and the sequencing of ITS1-5.8rRNA-ITS2 regions. We found that both dogs and cats harbour T. tenax, with prevalences of 8.1% and 4.1%, respectively. Considerably more dogs were infected with different species of the genus Trichomonas (30.6%), which we also identified in cats (6.6%). An analysis of the potential risk factors suggested that dogs of more than 3years old or with dental disease signs are more frequently infected with Trichomonas sp. than younger dogs or dogs without the disease signs, and that crossbreed dogs revealed increased rates of infection in comparison with purebred dogs. An analysis of the cat population suggested that Trichomonas sp. infection is lower in younger and crossbreed cats. Although the morphology of Trichomonas sp. is very similar to that of T. tenax, based on a phylogenetic analysis of ITS1-5.8rRNA-ITS2 regions and the ssrRNA genes, we consider Trichomonas sp. to represent a new trichomonad species, for which we propose the name Trichomonas brixi.