Immune cell arrival kinetics to peritoneum and role during murine-experimental trichomoniasis

Extracellular Traps in Patients Diagnosed With Bacterial Vaginosis, Trichomoniasis, Candidiasis, Noninfectious Vaginitis and Cytolytic Vaginosis

Vaginal infections are a public health problem associated with serious health complications due to the exacerbated inflammation they generate. Vaginal inflammation may also occur in some noninfectious processes, such as noninfectious vaginitis and cytolytic vaginosis. Immune system cells respond to infections through various mechanisms, such as the formation of extracellular traps (ETs), which are DNA networks associated with effector proteins. Many pathogens induce ETs formation in vitro, as occurs in some natural infections. A recent report indicates that human vaginal infections in vivo generate ETs. Therefore, in this study, we aimed to identify ETs in samples from 40 donors who were diagnosed with infectious (i.e., bacterial vaginosis, candidiasis and trichomoniasis) and noninfectious (i.e., noninfectious vaginitis and cytolytic vaginosis) vaginal inflammation. We were able to observe ETs by identifying the LL-37 peptide, which is associated with DNA networks. In seven vaginal swabs from the control group (formed by 19 donors without vaginal infection symptoms), we detected at least one pathogen per sample and observed ETs; thus, these donors were considered asymptomatic. The remaining 12 donors were confirmed to be healthy, as their exudates did not present any tested pathogens, sign of inflammation or ETs. ETs in vaginal inflammatory processes can worsen inflammation but may also help control infection.

Revealing the progression and pathologic features of intraperitoneal infection of Trichomonas vaginalis in mice via parasite α-actinin-based immunological detection

BACKGROUND

Trichomoniasis caused by Trichomonas vaginalis is the most prevalent nonviral sexually transmitted disease in women and has frequently damaged public health. To better use the animal model and take a step forward fully elucidating this pathogen, intraperitoneal infection of T. vaginalis in mice, one of the most common mouse models, was highly concerned.

METHODS

By adjusting the number of parasites inoculated, acute and chronic infection models were established. Pathological changes and the presence of T. vaginalis in organs were observed at different timepoints post inoculation using histological and TV-α-actinin-based immunological detection.

RESULTS

The results reconfirmed the correlation between inoculum size of parasites and infection duration, as well as the multiplication capacity of T. vaginalis in mouse enterocoelia or invaded organs. The progression and pathologic features of vital organs (e.g., liver and spleen) from mice intraperitoneally infected with T. vaginalis in both the acute and chronic groups were also revealed. In particular, a reliable immunological method based on TV-α-actinin was first verified to clearly present the invasion of T. vaginalis into infected mouse organs.

CONCLUSIONS

In brief, this study presented a clearer and more detailed pathologic characteristic of the intraperitoneal infection model, which probably provides more basic information for the use of this model in future studies. Especially, expanding on specific research applications of this model would be valuable.

Evaluation of PEN2-ATP6AP1 axis as an antiparasitic target for metformin based on phylogeny analysis and molecular docking

BACKGROUND

Metformin (Met), the first-line drug used in the treatment for type 2 diabetes mellitus, is effective against a variety of parasites. However, the molecular target of Met at clinical dose against various parasites remains unclear. Recently, low-dose Met (clinical dose) has been reported to directly bind PEN2 (presenilin enhancer protein 2) and initiate the lysosomal glucose-sensing pathway for AMPK activation via ATP6AP1 (V-type proton ATPase subunit S1), rather than perturbing AMP/ATP levels.

METHODS

To explore the possibility of PEN2-ATP6AP1 axis as a drug target of Met for the treatment of parasitic diseases, we identified and characterized orthologs of PEN2 and ATP6AP1 genes in parasites, by constructing phylogenetic trees, analyzing protein sequences and predicting interactions between Met and parasite PEN2.

RESULTS

The results showed that PEN2 and ATP6AP1 genes are only found together in a few of parasite species in the cestoda and nematoda groups. Indicated by molecular simulation, Met might function by interacting with PEN2 on V37/W38/E5 (Trichinella spiralis) with similar binding energy, and on F35/S39 (Caenorhabditis elegans) with higher binding energy, comparing to human PEN2. Hence, these results indicated that only the T. spiralis PEN2-ATP6AP1 axis has the potential to be the direct target of low-concentration Met. Together with contribution of host cells including immune cells in vivo, T. spiralis PEN2-ATP6AP1 axis might play roles in reducing parasite load at low-concentration Met. However, the mechanisms of low-concentration Met on other parasitic infections might be mainly achieved by regulating host cells, rather than directly targeting PEN2-ATP6AP1 axis.

CONCLUSIONS

These findings revealed the potential mechanisms by which Met treats various parasitic diseases, and shed new light on the development of antiparasitic drugs.

Trichomonas vaginalis triggers neutrophil extracellular traps reducing parasite integrity and growth

Trichomoniasis-caused by the parasite Trichomonas vaginalis-is associated with a high inflammatory process that may contribute to the risk of suffering from other medical complications. Our study focused on the in vitro interaction of T. vaginalis with human neutrophils because these are the most abundant cells implicated in the characteristic inflammatory process of trichomoniasis. This study showed that T. vaginalis and its surface glycoconjugates (lipophosphoglycan and/or lipoglycan) induced the formation of human neutrophil extracellular traps (NETs). After the trichomonad-neutrophil interaction, parasite integrity was at 32.9%, and the subsequent parasite growth was at 35.2% compared to those of control trophozoites (100%) incubated under the same conditions without neutrophils. In the presence of an antibody against the TLR-4 receptor, DNase I or micrococcal nuclease (MNase), neutrophils reduced the DNA fibres of the NETs and the amount of extracellular DNA, allowing a higher subsequent growth of T. vaginalis, at 52% with the anti-TLR-4 antibody and 62.6% with the enzymes. These results indicated that T. vaginalis induced the formation of extracellular traps by human neutrophils and, because of the interaction with neutrophils and NETs, parasite integrity and growth decreased.