“Trichomonas vaginalis is a parasite that resides in the human urogenital tract and causes trichomonosis, the most prevalent nonviral sexually transmitted disease. Nucleoside triphosphate diphosphohydrolase (NTPDase), which hydrolyzes extracellular di- and triphosphate nucleotides, and ecto-5′-nucleotidase, which hydrolyzes AMP, have been characterized in T. vaginalis. The aim of this study was to characterize the adenosine GW-572016 in vivo deaminase (ADA) activity in intact trophozoites of T. vaginalis. A strong inhibition in adenosine deamination was observed in the presence of calcium and magnesium, which was prevented by
EDTA. The apparent KM value for adenosine was 1.13 ± 0.07 mM. The calculated Vmax was 2.61 ± 0.054 nmol NH3 min−1 mg−1 protein. Adenosine deamination was inhibited in the presence of erythro-9-(2-hydroxy-3-nonyl)adenine. Semi-quantitative reverse transcriptase-PCR experiments were performed and both ADA-related genes ada(125) and ada(231) mRNA were expressed, although ada(231) in higher quantity when compared with the ada(125) : α-tubulin ratio. Furthermore, a phylogenetic analysis showed that the T. vaginalis sequences formed a clade with Entamoeba histolytica and Dictyostelium discoideum sequences, and it strongly suggests homologous functions in the T. vaginalis genome. The presence Panobinostat cell line of ADA activity in T. vaginalis may be important to modulate the
adenosine/inosine levels during infection and, consequently, to
maintain the anti-inflammatory properties through different nucleoside-signalling mechanisms. Trichomonas vaginalis is a protozoan parasite that causes trichomonosis, the most prevalent nonviral sexually transmitted isothipendyl disease worldwide (WHO, 2001). In women, the infection is clinically characterized by vaginitis and cervicitis (Petrin et al., 1998; Lehker & Alderete, 2000). The pathogen has been associated with serious health consequences including adverse pregnancy outcomes (Klebanoff et al., 2001), infertility (Grodstein et al., 1993), predisposition to cervical cancer (Viikki et al., 2000) and pelvic inflammatory disease (Cherpes et al., 2006), and it is a cofactor in HIV transmission and acquisition (Sorvillo et al., 2001; Van Der Pol et al., 2008). At the infection sites, tissue stress or injury takes place and intracellular ATP can be released into the extracellular environment. Extracellular nucleotides such as ATP play a role as danger-associated molecular patterns (DAMPs) or ‘alarmins’ by acting as signalling molecules that contribute to inflammation and immune responses (Hanley et al., 2004; Bours et al., 2006). The crucial factors in purinergic signalling are the stimulation of nucleotide release, their metabolism by enzymes acting in an extracellular manner and the presence of receptors that selectively bind the resulting products and mediate signal transduction (Gounaris & Selkirk, 2005).