Effect of DODAB Nano-Sized Cationic Bilayer Fragments against Leishmania amazonensis.

The dioctadecyldimethylammonium bromide (DODAB) is a double-chained cationic lipid with potent bactericide and fungistatic activities; however, its toxicity on protozoan parasites is still unknown. Here, we show the antileishmanial activity of DODAB nano-sized cationic bilayer fragments on stationary-phase promastigotes and amastigotes of Leishmania amazonensis, the causative agent of cutaneous leishmaniasis. Upon treatment with DODAB, we analyzed the parasite surface zeta-potential, parasite viability, cellular structural modifications, and intracellular proliferation. The DODAB cytotoxic effect was dose-dependent, with a median effective concentration (EC50) of 25 µM for both life-cycle stages, comparable to the reported data for bacteria and fungi. The treatment with DODAB changed the membrane zeta-potential from negative to positive, compromised the parasite's morphology, affected the cell size regulation, caused a loss of intracellular organelles, and probably dysregulated the plasma membrane permeability without membrane disruption. Moreover, the parasites that survived after treatment induced small parasitophorous vacuoles and failed to proliferate inside macrophages. In conclusion, DODAB displayed antileishmanial activity, and it remains to be elucidated how DODAB acts on the protozoan membrane. Understanding this mechanism can provide insights into the development of new parasite-control strategies.

Observational cross-sectional study of Trichomonas tenax in patients with periodontal disease attending a Chilean university dental clinic.

BACKGROUND: The oral flagellated protozoan Trichomonas tenax has been associated with patients with periodontal disease. However, no recent studies have been conducted on the prevalence of T. tenax in Chile. The aim of this study was to determine the presence of T. tenax in patients with periodontal disease, admitted to the Dental Clinic of the University of Antofagasta, Chile, through Polymerase Chain Reaction (PCR) amplification of the beta-tubulin gene. METHODS: An observational, cross-sectional study was conducted on 50 patients diagnosed with periodontal disease, 20 of them with gingivitis and 30 with periodontitis. T. tenax was identified by PCR amplification of the beta-tubulin gene. Associations between the protozoan and periodontal disease or the presence of risk factors to establish T. tenax infection were determined using the chi-square test and binary logistic regression analysis. RESULTS: T. tenax was present in 28 out of 50 (56%) of patients with periodontal disease, and was more prevalent when associated with periodontitis (21 out of 30; 70%) than dental plaque-induced gingivitis (7 out of 20; 35%). Non-statistically-significant associations were observed between the presence of T. tenax and age, gender, smoking habit or diabetes. Statistically significant associations were observed between the presence of T. tenax and periodontal disease, and between T. tenax and the Periodontal Screening and Recording (PSR) index. CONCLUSION: T. tenax showed a high presence in patients with progressive states of periodontal diseases. Consequently, T. tenax detection is strongly recommended in patients with periodontal disease diagnosis and with a PSR index greater than 3.

A protein phosphatase 1 gamma (PP1γ) of the human protozoan parasite Trichomonas vaginalis is involved in proliferation and cell attachment to the host cell.

In this work, evidence for a critical role of Trichomonas vaginalis protein phosphatase 1 gamma (TvPP1γ) in proliferation and attachment of the parasite to the mammalian cell is provided. Firstly, proliferation and attachment of T. vaginalis parasites to HeLa cells was blocked by calyculin A (CA), a potent PP1 inhibitor. Secondly, it was demonstrated that the enzyme activity of native and recombinant TvPP1γ proteins was inhibited by CA. Thirdly, reverse genetic studies confirmed that antisense oligonucleotides targeted to PP1γ but not PP1α or ß inhibited proliferation and attachment of trichomonads CA-treated parasites underwent cytoskeletal modifications, including a lack of axostyle typical labelling, suggesting that cytoskeletal phosphorylation could be regulated by a CA-sensitive phosphatase where the role of PP1γ could not be ruled out. Analysis of subcellular distribution of TvPP1γ by cell fractionation and electron microscopy demonstrated the association between TvPP1γ and the cytoskeleton. The expression of adhesins, AP120 and AP65, at the cell surface was also inhibited by CA. The concomitant inhibition of expression of adhesins and changes in the cytoskeleton in CA-treated parasites suggest a specific role for PP1γ -dependent dephosphorylation in the early stages of the host-parasite interaction. Molecular modelling of TvPP1γ showed the conservation of residues critical for maintaining proper folding into the gross structure common to PP1 proteins. Taken together, these results suggest that TvPP1γ could be considered a potential novel drug target for treatment of trichomoniasis.