Trichomonas vaginalis perturbs the junctional complex in epithelial cells

Endocytosis in anaerobic parasitic protists

The incorporation of different molecules by eukaryotic cells occurs through endocytosis, which is critical to the cell's survival and ability to reproduce. Although this process has been studied in greater detail in mammalian and yeast cells, several groups working with pathogenic protists have made relevant contributions. This review analysed the most relevant data on the endocytic process in anaerobic protists (Entamoeba histolytica, Giardia intestinalis, Trichomonas vaginalis, and Tritrichomonas foetus). Many protozoa can exert endocytic activity across their entire surface and do so with great intensity, as with E. histolytica. The available data on the endocytic pathway and the participation of PI-3 kinase, Rab, and Rho molecular complexes is reviewed from a historical perspective.

Trichomonas vaginalis infection is associated with increased risk of cervical carcinogenesis: A systematic review and meta-analysis of 470 000 patients

BACKGROUND

Trichomonas vaginalis infection is the most prevalent non-viral sexually transmitted infection (STI) in women and has been suggested as a risk factor for developing cervical cancer.

OBJECTIVE

We aimed to investigate the associations between T. vaginalis infection and cervical carcinogenesis.

SEARCH STRATEGY

A comprehensive systematic search was conducted in five databases on 21 October 2021.

SELECTION CRITERIA

Studies assessing the relationship between T. vaginalis infection, HPV co-infections, cervical dysplasia, and cervical cancer were found eligible.

DATA COLLECTION AND ANALYSIS

Summary estimates for pooled odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated with a random-effects model. Statistical heterogeneity was measured with I2 and Cochran's Q tests.

MAIN RESULTS

The 29 articles included 473 740 women, of whom 8518 were T. vaginalis-positive. Our results showed that T. vaginalis-infected women had 1.79 times higher odds of being diagnosed with HPV co-infection (95% CI 1.27-2.53; I2 95%). We also found that T. vaginalis infection was associated with high-grade squamous intraepithelial lesion diagnosis (OR 2.34, 95% CI 1.10-4.95; I2 75%) and cervical cancer (OR 5.23, 95% CI 3.03-9.04; I2 3%).

CONCLUSIONS

Our results showed an association between T. vaginalis and cervical carcinogenesis in sexually active women.

Trichomonas vaginalis adhesion protein 65 (TvAP65) modulates parasite pathogenicity by interacting with host cell proteins

Trichomonas vaginalis (T. vaginalis) is a widespread and important sexually transmitted pathogen. Adherence to the surface of the host cell is the precondition forthis parasite's parasitism and pathogenicity. Adhesion protein 65 (TvAP65) plays a key role in the process of adhesion. However, how TvAP65 mediates the adhesion and pathogenicity of T. vaginalis to host cellsis unclear. In this study, we knocked down the expression of TvAP65 in trophozoites by small RNA interference. The number of T. vaginalis trophozoites adhering to VK2/E6E7 cells was decreased significantly, and the inhibition of VK2/E6E7 cells proliferation and VK2/E6E7 cells apoptosis and death induced by T. vaginalis were reduced, after the expression of TvAP65 was knocked down. Animal challenge experiments showed that the pathogenicity of trophozoites was decreased by passive immunization with anti-rTvAP65 PcAbs or blocking the TvAP65 protein. Immunofluorescence analysis showed that TvAP65 could bind to VK2/E6E7 cells. In order to screen the molecules interacting with TvAP65 on the host cells, we successfully constructed the cDNA library of VK2/E6E7 cells, and thirteen protein molecules interacting with TvAP65 were screened by yeast two-hybrid system. The interaction between TvAP65 and BNIP3 was further confirmed by coimmunoprecipitation and colocalization. When both TvAP65 and BNIP3 were knocked down by small RNA interference, the number of T. vaginalis adhering to VK2/E6E7 cells and the inhibition of VK2/E6E7 cells proliferation were significantly lower than those of the group with knockdown of TvAP65 or BNIP3 alone. Therefore, the interaction of TvAP65 and BNIP3 in the pathogenesis of T. vaginalis infecting host cells is not unique and involves other molecules. Our study elucidated that the interaction between TvAP65 and BNIP3 mediated the adhesion and pathogenicity of T. vaginalis to host cells, provided a basis for searching for the drug targets of anti-T. vaginalis, and afforded new ideas for the prevention and treatment of trichomoniasis.

The interaction between adhesion protein 33 (TvAP33) and BNIP3 mediates the adhesion and pathogenicity of Trichomonas vaginalis to host cells

BACKGROUND

Trichomonas vaginalis is a widespread and important sexually transmitted pathogen. Adherence to the surface of the host cell is the precondition for the parasitism and pathogenicity of this parasite. Trichomonas vaginalis adhesion protein 33 (TvAP33) plays a key role in the process of adhesion, but how this protein mediates the adhesion and pathogenicity of T. vaginalis to host cells is unclear.

METHODS

The expression of TvAP33 in trophozoites was knocked down by small interfering RNA. VK2/E6E7 cells and mice infected with T. vaginalis were used to evaluate the pathogenicity of T. vaginalis. We constructed a complementary DNA library of VK2/E6E7 cells and screened the protein molecules interacting with TvAP33 by the yeast two-hybrid system. The interaction between TvAP33 and BNIP3 (Bcl-2 interacting protein 3) was analyzed by co-immunoprecipitation and colocalization.

RESULTS

Following knockdown of TvAP33 expression, the number of T. vaginalis trophozoites adhering to VK2/E6E7 cells decreased significantly, and the inhibition of VK2/E6E7 cell proliferation and VK2/E6E7 cell apoptosis and death induced by T. vaginalis were reduced. Animal challenge experiments showed that the pathogenicity of trophozoites decreased following passive immunization with TvAP33 antiserum or blocking of the TvAP33 protein. Immunofluorescence analysis revealed that TvAP33 could bind to VK2/E6E7 cells. Eighteen protein molecules interacting with TvAP33 were identified by the yeast two-hybrid system. The interaction between TvAP33 and BNIP3 was further confirmed by co-immunoprecipitation and colocalization. When the expression of both TvAP33 and BNIP3 in trophozoites was knocked down by small RNA interference, the number of T. vaginalis adhering to VK2/E6E7 cells and the inhibition of VK2/E6E7 cell proliferation were significantly lower compared to trophozoites with only knockdown of TvAP33 or only BNIP3. Therefore, the interaction of TvAP33 and BNIP3 in the pathogenesis of T. vaginalis infecting host cells is not unique and involves other molecules.

CONCLUSIONS

Our study showed that the interaction between TvAP33 and BNIP3 mediated the adhesion and pathogenicity of T. vaginalis to host cells, providing a basis for searching for drug targets for T. vaginalis as well as new ideas for the prevention and treatment of trichomoniasis.

Trichomonas tenax induces barrier defects and modulates the inflammatory cytotoxicity of gingival and pulmonary epithelial cells

BACKGROUND

Trichomonas tenax is a single-cell flagellated anaerobic organism, commensal in the human oral cavity. Although a previous study indicated that T. tenax could cause cell damage and phagocytose host epithelial cells, its pathological effects on gum cells remain unknown. Furthermore, several case reports have detected T. tenax in several patients with empyema and/or pleural effusion, which may have been aspirated from the oral cavity. However, the cytotoxic effects and immune responses of alveolar cells are unknown. Therefore, we aimed to determine the cytotoxic and immune effects of T. tenax on gums and pulmonary cell lines. The cytopathic effect and lactate dehydrogenase (LDH) cytotoxicity assays were used to determine the level of cell damage in gum and lung epithelial cells. Western blot was used to determine the disruption of cell junctions. Finally, epithelial cell cytokines were measured using ELISA to elucidate the immune response to T. tenax.

RESULTS

We found that T. tenax induced a cytotoxic effect on gum epithelial cells by disrupting cell junctions; however, it hardly triggered cellular damage in alveolar A549 cells and mucoepidermoid NCI-H292 cells. Furthermore, T. tenax induced the production of IL-6 at a low multiplicity of infection (MOI) in gum, A549, and NCI-H292 cells.

CONCLUSIONS

Our results suggest that T. tenax can trigger gingival cell cytotoxicity, disrupt cell junctions, and induce IL-6 production in gingival and pulmonary cell lines.

Distinct features of the host-parasite interactions between nonadherent and adherent Trichomonas vaginalis isolates

Cytoadherence of Trichomonas vaginalis to human vaginal epithelial cells (hVECs) was previously shown to involve surface lipoglycans and several reputed adhesins on the parasite. Herein, we report some new observations on the host-parasite interactions of adherent versus nonadherent T. vaginalis isolates to hVECs. The binding of the TH17 adherent isolate to hVECs exhibited an initial discrete phase followed by an aggregation phase inhibited by lactose. T. vaginalis infection immediately induced surface expression of galectin-1 and -3, with extracellular amounts in the spent medium initially decreasing and then increasing thereafter over the next 60 min. Extracellular galectin-1 and -3 were detected on the parasite surface but only the TH17 adherent isolate could uptake galectin-3 via the lysosomes. Only the adherent isolate could morphologically transform from the round-up flagellate with numerous transient protrusions into a flat amoeboid form on contact with the solid surface. Cytochalasin D challenge revealed that actin organization was essential to parasite morphogenesis and cytoadherence. Real-time microscopy showed that parasite exploring and anchoring on hVECs via the axostyle may be required for initial cytoadherence. Together, the parasite cytoskeleton behaviors may collaborate with cell surface adhesion molecules for cytoadherence. The nonadherent isolate migrated faster than the adherent isolate, with motility transiently increasing in the presence of hVECs. Meanwhile, differential histone acetylation was detected between the two isolates. Also, TH17 without Mycoplasma symbiosis suggests that symbiont might not determine TH17 innate cytoadherence. Our findings regarding distinctive host-parasite interactions of the isolates may provide novel insights into T. vaginalis infection.

Association between common vaginal and HPV infections and results of cytology test in the Zhoupu District, Shanghai City, China, from 2014 to 2019

Background

HPV (human papillomavirus) is an important cause of cervical cancer. Cervical-vaginal infection with pathogens, such as herpes simplex virus (HSV), bacterial vaginosis Trichomonas vaginalis and vaginal candidiasis could be a cofactor. This study aimed to assess the relationship between vaginal infection with HPV genotype and cytology test results and analyze the relationship between vaginal and HPV infections and cervical cancer.

Methods

We performed a district-based study to elucidate the relationship among the vaginal and HPV infections and cervical cancer. We collected the cervical exfoliation data of 23,724 women admitted to the Shanghai Zhoupu Hospital and received ThinPrep cytology test (TCT) and HPV detection between 2014 and 2019.

Results

Total vaginal infection rate was 5.3%, and the HPV-positive group had a slightly higher vaginal infection rate than the HPV-negative group (P < 0.01). The incidence rate of cervical intraepithelial neoplasia or cervical cancer with vaginal infection was higher than without vaginal infection (P < 0.001).

Conclusion

HPV/vaginal infection-positive women tended to have abnormal results of TCT. Women with vaginal infection were more likely to develop HPV infection. HSV combined with HPV infection was noted as a causal factor for HSIL.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-022-01850-x.

The Antioxidant Effect of Natural Antimicrobials in Shrimp Primary Intestinal Cells Infected with Nematopsis messor

Nematopsis messor infections severely impact on shrimp’s health with devastating economic consequences on shrimp farming. In a shrimp primary intestinal cells (SGP) model of infection, a sub-inhibitory concentration (0.5%) of natural antimicrobials (Aq) was able to reduce the ability of N. messor to infect (p < 0.0001). To prevent N. messor infection of SGP cells, Aq inhibits host actin polymerization and restores tight junction integrity (TEER) and the expression of Zo-1 and occluding. The oxidative burst, caused by N. messor infection, is attenuated by Aq through the inhibition of NADPH-produced H2O2. Simultaneous to the reduction in H2O2 released, the activity of catalase (CAT) and superoxide dismutase (SOD) were also significantly increase (p < 0.0001). The antimicrobial mixture inactivates the ERK signal transduction pathway by tyrosine dephosphorylation and reduces the expression of DCR2, ALF-A, and ALF-C antimicrobial peptides. The observed in vitro results were also translated in vivo, whereby the use of a shrimp challenge test, we show that in N. messor infected shrimp the mortality rate was 68% compared to the Aq-treated group where the mortality rate was maintained at 14%. The significant increase in CAT and SOD activity in treated and infected shrimp suggested an in vivo antioxidant role for Aq. In conclusion, our study shows that Aq can efficiently reduce N. messor colonization of shrimp’s intestinal cells in vitro and in vivo and the oxidative induced cellular damage, repairs epithelial integrity, and enhances gut immunity.

Dysbiosis of fecal microbiota in cats with naturally occurring and experimentally induced Tritrichomonas foetus infection

The protozoal pathogen Tritrichomonas foetus infects the colon of domestic cats and is a major cause of chronic colitis and diarrhea. Treatment failure is common, but antibiotics may improve clinical signs in a subset of cats, leading researchers to question involvement of the colonic microbiota in disease pathogenesis. Studies performed in women with venereal Trichomonas vaginalis infections have revealed that dysbiosis of host microbiota contributes to pathogenicity with similar findings also found in mice with intestinal Tritrichomonas musculis The aim of this study was to characterize differences in the fecal microbiota of cats with and without naturally occurring T. foetus infection and in a group of kittens prior to and after experimentally induced infection. Archived fecal DNA from cats undergoing testing for T. foetus infection (n = 89) and experimentally infected kittens (n = 4; at pre-, 2 weeks, and 9 weeks post-infection) were analyzed by sequencing of 16S rRNA genes. Amongst the naturally infected population, the genera Megamonas and Helicobacter were significantly increased in prevalence and abundance in cats testing positive for T. foetus infection. In the group of four experimentally infected kittens, fecal samples post-infection had significantly lower abundance of genus Dialister and Megamonas and greater abundance of the class Betaproteobacteria and family Succinivibrionaceae. We hypothesize that T. foetus promotes dysbiosis by competition for fermentable substrates used by these bacteria and that metabolic byproducts may contribute to the pathogenesis of colonic inflammation and diarrhea. Future studies are warranted for the measurement of fecal concentrations of microbial and protozoal metabolites in cats with T. foetus infection for the identification of potential therapeutic targets.

Rapid electrostatic DNA enrichment for sensitive detection of Trichomonas vaginalis in clinical urinary samples

Estimated to be the most common non-viral sexually transmitted infection globally, Trichomonas vaginalis (TV) can lead to pelvic inflammatory disease, pregnancy complications, and increased risk of acquiring and transmitting HIV. Once diagnosed, TV infection can be treated with oral antibiotics; however, infected individuals are often asymptomatic and do not seek treatment. The WHO and others have identified a need for point-of-care tests to expand access to TV testing and screening; ideal test characteristics include high sensitivity and specificity and the ability to use urine as a sample type, rather than invasively collected swab samples. Here, we report on a proof-of-concept prototype for rapid, electrostatic enrichment of DNA from urine samples and demonstrate the use of large volumes of urine to increase sensitivity of downstream nucleic acid amplification testing. We developed an internally controlled thermophilic helicase-dependent amplification (tHDA) assay with lateral flow immunoassay readout and demonstrate that this tHDA assay can be performed directly on our DNA capture filter. We validated our method using clinical urine samples with qPCR-quantified TV loads. Using 62 clinical urine samples and a simple sample processing device, our tHDA assay displayed 96.6% sensitivity and 100% specificity. Our analytical limit of detection was found to be approximately 7 genomic equivalents of TV DNA per mL of sample when 1 mL of sample was tested, comparable to existing isothermal tests for TV. Using large-volume simulated samples (40 mL of buffered urine with spiked-in TV DNA), we also demonstrated that sensitivity could be improved 28-fold to 0.25 genomic equivalents of TV DNA per mL, with a sample processing time of only 2 minutes.

Correlation between Common Lower Genital Tract Microbes and High-Risk Human Papillomavirus Infection

Background

High-risk human papillomavirus (hr-HPV) infection is a necessary cause of cervical cancer. However, other common lower genital tract microbes may increase hr-HPV infection and their related cervical cytopathy.

Methods

To confirm this hypothesis, cervical brush and vaginal swab specimens were collected from 826 adult patients who were divided into the hr-HPV-positive group (254) and the negative group (572) by real-time PCR assay. Cervical specimens were tested for Ureaplasma parvum (UP), Ureaplasma urealyticum (UU), and Chlamydia trachomatis (CT) using PCR analysis. Vaginal secretion was detected for Trichomonas vaginalis (TV), Candida spp., and bacterial vaginosis (BV) with conventional assay.

Results

Among hr-HPV-positive women, UP was found in 51.6%, UU in 15.4%, CT in 15.7%, Candida spp. in 11.0%, TV in 3.1%, and BV in 20.5%. In the hr-HPV-negative group, UP was positive in 36.2%, UU in 8.6%, CT in 4.0%, Candida spp. in 12.4%, TV in 0.2%, and BV in 7.0%. Multivariate logistic regression analysis with age-adjusted showed that UU (OR, 1.757), UP (OR, 1.804), CT (OR, 3.538), BV (OR, 3.020), and TV (OR, 14.109) were risk factors on hr-HPV infection (P < 0.05).

Conclusion

These microbes might induce cervical chronic inflammation that would damage the mucosal barrier and immune protection to promote the infection of hr-HPV.

Reduced Trichomonas vaginalis viability in mice pretreated with parasite DNA

Trichomonas vaginalis is an extracellular parasite that colonizes the human urogenital tract leading to trichomoniasis, the most common sexually-transmitted non-viral disease worldwide. The immune response plays a critical role in the host defense against this parasite. Trichomonas' DNA contains unmethylated CpG motifs (CpGDNA) that in other microorganisms act as modulators of the immune response. However, the molecular mechanisms responsible for CpGDNA immune modulation are still unclear. As macrophages participate in the first line of defense against infection, we investigated the type of immune response of murine macrophages to T. vaginalis DNA (TvDNA). We observed high expression of the proinflammatory cytokines IL-6 and IL-12p40 in macrophages stimulated with TvDNA. In contrast, the anti-inflammatory response, assessed by IL-10 and IL-13 mRNA expression was delayed. This suggests that the immune response induced by TvDNA is modulated through cytokine production, mediated partly by NADPH-oxidase activity, as TvDNA induced reactive species of oxygen production and a rounded morphology in macrophages indicative of an M1 phenotype. Furthermore, infected mice pretreated with TvDNA displayed persistent vulvar inflammation and decreased parasite viability consistent with higher proinflammatory cytokine levels during infection compared to untreated mice. Overall, our findings suggest that TvDNA pretreatment modulates the immune response favouring parasite elimination.

Cooperative Interactions between Trichomonas vaginalis and Associated Bacteria Enhance Paracellular Permeability of the Cervicovaginal Epithelium by Dysregulating Tight Junctions

The human protozoan Trichomonas vaginalis is the causative agent of trichomoniasis, a prevalent sexually transmitted infection, which is accompanied by a species-diversified vaginal microbiota named community state type IV (CST-IV). Coincidently, CST-IV includes species associated with bacterial vaginosis (e.g. Gardnerella vaginalis, Atopobium vaginae, and Prevotella bivia). Both diseases are linked to the transmission of human immunodeficiency virus (HIV) and preterm birth, which complications are likely to result from the disruption of the cervicovaginal epithelial barrier. Here, we show that paracellular permeability of fluorescein isothiocyanate (FITC)-dextran through a monolayer of human ectocervical cells (hECs) is increased as a consequence of the activity of T. vaginalis and the aforementioned species of CST-IV bacteria cooperatively. T. vaginalis enhances paracellular permeability of hECs two times more than the individual bacterial species, by up to ∼10% versus ∼5%, respectively. However, any two or all three bacterial species are capable of synergizing this effect. T. vaginalis and the bacteria together increase the paracellular permeability of hECs by ∼50%, which is 5 to 10 times more than the results seen with the protozoan or bacteria alone. This effect is accompanied by enhancement of phosphatase activity, while phosphatase inhibition results in preservation of the integrity of the ectocervical cell monolayer. In addition, these microorganisms induce changes in the expression of tight junction proteins, particularly occludin, and of proinflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α). Together, our findings establish that cooperative interactions between CST-IV bacteria and T. vaginalis enhance the paracellular permeability of the cervicovaginal epithelium by disturbing the integrity of the tight junction complex. Our study results highlight the importance of understanding the contribution of the vaginal microbiota to trichomoniasis.

Adherens junctions and desmosomes are damaged by Entamoeba histolytica: Participation of EhCPADH complex and EhCP112 protease

Entamoeba histolytica trophozoites adhere to epithelium at the cell-cell contact and perturb tight junctions disturbing the transepithelial electrical resistance. Behind tight junctions are the adherens junctions (AJs) that reinforce them and the desmosomes (DSMs) that maintain the epithelium integrity. The damage produced to AJs and DMSs by this parasite is unknown. Here, we studied the effect of the trophozoites, the EhCPADH complex, and the EhCP112 recombinant enzyme (rEhCP112) on AJ and DSM proteins. We found that trophozoites degraded β-cat, E-cad, Dsp l/ll, and Dsg-2 with the participation of EhCPADH and EhCP112. After contact of epithelial cells with trophozoites, immunofluorescence and transmission electron microscopy assays revealed EhCPADH and rEhCP112 at the intercellular space where they colocalised with β-cat, E-cad, Dsp l/ll, and Dsg-2. Moreover, our results suggested that rEhCP112 could be internalised by caveolae and clathrin-coated vesicles. Immunoprecipitation assays showed the interaction of EhCPADH with β-cat and Dsp l/ll. Besides, in vivo assays demonstrated that rEhCP112 concentrates at the cellular borders of the mouse intestine degrading E-cad and Dsp I/II. Our research gives the first clues on the trophozoite attack to AJs and DSMs and point out the role of the EhCPADH and EhCP112 in the multifactorial event of trophozoites virulence.

Trichomonas tenax and periodontal diseases: a concise review

Periodontal diseases (gingivitis and periodontitis), result from a disruption of the host-oral microbiome homoeostasis. Whereas the pathological role of some specific bacterial strains during periodontal diseases is well documented, the impact of parasites in periodontium pathophysiology is still under debate. This review aims to collect data about the prevalence and the potential role of Trichomonas tenax during periodontal diseases. Data from 47 studies revealed that T. tenax prevalence in diseased periodontium ranged from 0 to 94·1%. The prevalence of oral protozoan infections was found to be largely greater in patients with periodontal diseases than with healthy periodontium. The parasite detection was mainly performed by direct microscopy. Trichomonas tenax presence was clearly correlated with periodontal disease. The high heterogeneity of its periodontal prevalence may be correlated with the diversity of the population screened (age, sex, systemic diseases), and the methods used for diagnosis. This protozoan seems to have the capacity to be involved in the inflammatory process of gum disease. Animal experimentation, using relevant physiopathological models of periodontitis, needs to be performed to investigate the ability of T. tenax to cause and/or worsen the disease. Further investigations using standardized experimental designs of epidemiologic studies are also needed.

Interaction between Trichomonas vaginalis and the Prostate Epithelium

Most men infected with Trichomonas vaginalis are asymptomatic and can remain undiagnosed and untreated. This has been hypothesized to result in chronic persistent prostatic infection. Adhesion of the protozoan organisms to mucosal cells is considered a first and prerequisite step for T. vaginalis infection. Adhesion of T. vaginalis to prostate epithelial cells has not yet been observed; however, there are several reports about inflammation of prostate epithelial cells induced by T. vaginalis. The aim of this study was to investigate whether adhesion and cytotoxicity of T. vaginalis are involved in inflammation of prostate epithelial cells. When RWPE-1 cells were infected with T. vaginalis (1:0.4 or 1:4), adhesion of T. vaginalis continuously increased for 24 hr or 3 hr, respectively. The cytotoxicity of prostate epithelial cells infected with T. vaginalis (RWPE-1: T. vaginalis=1:0.4) increased at 9 hr; at an infection ratio of 1:4, cytotoxicity increased after 3 hr. When the RWPE-1 to T. vaginalis ratio was 1:0.4 or 1:4, production of IL-1β, IL-6, CCL2, and CXCL8 also increased. Epithelial-mesenchymal transition (EMT) was verified by measuring decreased E-cadherin and increased vimentin expression at 24 hr and 48 hr. Taken together, the results indicate that T. vaginalis adhered to prostate epithelial cells, causing cytotoxicity, pro-inflammatory cytokine production, and EMT. Our findings suggest for the first time that T. vaginalis may induce inflammation via adhesion to normal prostate epithelial cells.

Association between high risk human papillomavirus infection and co-infection with Candida spp. and Trichomonas vaginalis in women with cervical premalignant and malignant lesions

BACKGROUND

Human papillomavirus (HPV) is the necessary cause of cervical cancer. Cervico-vaginal infection with pathogens like Chlamydia is a likely cofactor. The interactions between HPV, Trichomonas vaginalis (TV) and Candida spp. are less understood, though inflammation induced by these pathogens has been demonstrated to facilitate oncogenesis.

OBJECTIVE

Our study aimed to evaluate the association between Candida spp. and TV co-infection with HPV in cervical oncogenesis.

STUDY DESIGN

Women with normal cervix who were high-risk HPV-negative (N=104) and HPV-positive (N=105); women with CIN 1 (N=106) and CIN 2/CIN 3 (N=62) were recruited from a community based cervical cancer screening program. Cervical cancer patients (N=106) were recruited from a tertiary care oncology clinic. High-risk HPV was detected by Hybrid Capture II technique; Candida spp. and TV were detected by culturing the high vaginal swabs followed by microscopic examination in all. The disease status was established by histopathology in all the women.

RESULT

HPV-positive women had significantly higher risk of having precursor lesions (of any grade) and cancer compared to HPV-negative women. Candida spp. or TV infection did not alter the risk of low grade or high grade lesions among HPV- positive women. HPV positive women co-infected with TV had higher risk of cervical cancer but not those co-infected with Candida spp.

CONCLUSION

The higher risk of cancer observed in the women co-infected with HPV and TV without any enhanced risk of CIN 3 suggests secondary infection of the malignant growth by TV rather than any causal role. Co-infection with Candida spp. and/or TV infection did not increase the carcinogenic effect of HPV on cervix.

Associations Between Vaginal Infections and Potential High-risk and High-risk Human Papillomavirus Genotypes in Female Sex Workers in Western Kenya

PURPOSE

Infection with and persistence of high-risk human papillomavirus (HR HPV) are the strongest risk factors for cervical cancer. Little is known about the prevalence and role of concurrent sexually transmitted infections (STIs) found in HPV-infected female sex workers (FSW) in Africa. This study purports to test our a priori hypotheses that STIs are associated with genotypes pertaining to the α-group species 9. The objectives were to determine the prevalence of bacterial vaginosis (BV), Trichomonas vaginalis, and Candida spp in FSW, the association between these STIs and the prevalence of any potential HR and HR HPV genotypes in FSWs.

METHODS

A cross-sectional study design of 616 FSW from Western Kenya aged between 18 and 61 years during 2009-2015 using a peer recruitment sampling strategy. Inclusion criteria for the study entailed female sex and >18 years of age and having engaged in transactional sex in exchange for money, goods, services, or drugs in the last 3 months. Women were excluded if they were pregnant, <18 years of age, had a history of cervical dysplasia or cancer, had current abnormal bleeding, or had a hysterectomy.

FINDINGS

Of the FSW, 33.3% had HIV and 57.7% harbored a potential HR and HR HPV genotype. The 2 most prevalent potential HR and HR genotypes were HPV 16 (16.10%) and HPV 59 (12.20%). BV was the most common infection (48.3%), followed by Trichomonas vaginalis (31.4%) and Candida spp (19.9%). A multivariate regression revealed significant associations with both α-group 9 and 6; BV and HPV 58 (adjusted odds ratio [aOR] = 2.3; 95% CI, 1.0-5.2; P = 0.05), Trichomonas vaginalis and HPV 31 and HPV 35 (aOR = 2.0; 95% CI, 1.0-3.8; P = 0.04 and aOR = 1.8; 95% CI, 1.0-3.3, P = 0.05 respectively); and between Candida spp and HPV 53 (aOR = 2.0; 95% CI, 1.1-4.0; P = 0.03) and 16 (aOR = 1.9; 95% CI, 1.1-3.3; P = 0.03).

IMPLICATIONS

Snowball sampling may have inadvertently excluded FSW less likely to benefit from a social network. Significant associations between BV and HPV 58 and between Candida spp and HPV 16 and 53 suggest the need for sexually transmitted disease management within a cervical cancer prevention program. The probable synergistic effects of the vaginal microbiota should be elucidated, especially within this vulnerable population. Given the potential for FSW to transmit STIs, robust epidemiologic sampling methods are urgently required that account for the heterogeneity of the FSW population.

Mechanisms of Tritrichomonas foetus Pathogenicity in Cats with Insights from Venereal Trichomonosis

Almost 20 years has passed since trichomonosis was first recognized as a potential cause of diarrhea in domestic cats. Despite progress in confirming disease causation, developing means for diagnosis, and identifying approaches to treatment of the infection, we still know very little about how this parasite causes diarrhea. With increasing recognition of resistance of trichomonosis to treatment with 5‐nitroimidazole drugs, new treatment strategies based on an understanding of disease pathogenesis are needed. In this review, lessons learned from the pathogenesis of venereal trichomonosis in people and cattle are applied to clinical observations of trichomonosis in cats in effort to generate insight into areas where further research may be beneficial.

Is Trichomonas tenax a Parasite or a Commensal?

Trichomonas tenax is considered a commensal organism found under poor oral hygiene conditions. T. tenax presents morphological similarities with T. vaginalis, and there are doubts concerning whether this protist is a parasite and whether it is a genetic variant of T. vaginalis. This study aimed to investigate the capacity of T. tenax to cause mammalian cell damage and compare its cytotoxicity with that of T. vaginalis. Protozoan-host cell interaction assays were performed with Madin-Darby canine kidney, HeLa, and gum cells and 3D spheroids, which were examined by scanning electron and transmission electron microscopy. Cellular viability experiments were also performed. T. tenax attached and had different forms when interacting with mammalian cells and caused damage with time-dependent host-cell viability. We observed that T. tenax produced plasma membrane projections and phagocytosed portions of the mammalian cells. In addition, T. tenax caused membrane blebbing and apoptotic bodies in HeLa cells, thus inducing cell death. Spheroids were also used in interaction assays with T. tenax and they were damaged by these cells. This study shows that T. tenax fulfills the requisites of a parasite, causing damage to different mammalian cells and behaving similarly to T. vaginalis when in contact with target cells in vitro.

Claudin-4 is required for AMPK-modulated paracellular permeability in submandibular gland cells

Tight junction plays an important role in mediating paracellular permeability in epithelia. We previously found that activation of AMP-activated protein kinase (AMPK) increased saliva secretion by modulating paracellular permeability in submandibular glands. However, the molecular mechanisms underlying AMPK-modulated paracellular permeability are unknown. In this study, we found that AICAR, an AMPK agonist, increased saliva secretion in the isolated rat submandibular glands, decreased transepithelial electrical resistance (TER), and increased 4 kDa FITC-dextran flux in cultured SMG-C6 cells. AICAR also induced redistribution of tight junction protein claudin-4, but not claudin-1, claudin-3, occludin, or ZO-1, from the cytoplasm to the membrane. Moreover, knockdown of claudin-4 by shRNA suppressed while claudin-4 re-expression restored the TER and 4 kDa FITC-dextran flux responses to AICAR. Additionally, AICAR increased ERK1/2 phosphorylation, and inhibition of ERK1/2 by U0126, an ERK1/2 kinase inhibitor, or by siRNA decreased AICAR-induced TER responses. AICAR induced the serine S199 phosphorylation of claudin-4 and enhanced the interaction of claudin-4 and occludin. Furthermore, pretreatment with U0126 significantly suppressed AMPK-modulated phosphorylation, redistribution, and interaction with occludin of claudin-4. Taken together, these results indicated that claudin-4 played a crucial role in AMPK-modulated paracellular permeability and ERK1/2 was required in AMPK-modulated tight junction barrier function in submandibular gland.

Trichomonas vaginalis: Clinical relevance, pathogenicity and diagnosis

Trichomonas vaginalis is the etiological agent of trichomoniasis, the most prevalent non-viral sexually transmitted disease worldwide. Trichomoniasis is a widespread, global health concern and occurring at an increasing rate. Infections of the female genital tract can cause a range of symptoms, including vaginitis and cervicitis, while infections in males are generally asymptomatic. The relatively mild symptoms, and lack of evidence for any serious sequelae, have historically led to this disease being under diagnosed, and under researched. However, growing evidence that T. vaginalis infection is associated with other disease states with high morbidity in both men and women has increased the efforts to diagnose and treat patients harboring this parasite. The pathology of trichomoniasis results from damage to the host epithelia, caused by a variety of processes during infection and recent work has highlighted the complex interactions between the parasite and host, commensal microbiome and accompanying symbionts. The commercial release of a number of nucleic acid amplification tests (NAATs) has added to the available diagnostic options. Immunoassay based Point of Care testing is currently available, and a recent initial evaluation of a NAAT Point of Care system has given promising results, which would enable testing and treatment in a single visit.

Biological roles of cysteine proteinases in the pathogenesis of Trichomonas vaginalis

Human trichomonosis, infection with Trichomonas vaginalis, is the most common non-viral sexually transmitted disease in the world. The host-parasite interaction and pathophysiological processes of trichomonosis remain incompletely understood. This review focuses on the advancements reached in the area of the pathogenesis of T. vaginalis, especially in the role of the cysteine proteinases. It highlights various approaches made in this field and lists a group of trichomonad cysteine proteinases involved in diverse processes such as invasion of the mucous layer, cytoadherence, cytotoxicity, cytoskeleton disruption of red blood cells, hemolysis, and evasion of the host immune response. A better understanding of the biological roles of cysteine proteinases in the pathogenesis of this parasite could be used in the identification of new chemotherapeutic targets. An additional advantage could be the development of a vaccine in order to reduce transmission of T. vaginalis.

Cysteine protease activity of feline Tritrichomonas foetus promotes adhesion-dependent cytotoxicity to intestinal epithelial cells

Trichomonads are obligate protozoan parasites most renowned as venereal pathogens of the reproductive tract of humans and cattle. Recently, a trichomonad highly similar to bovine venereal Tritrichomonas foetus but having a unique tropism for the intestinal tract was recognized as a significant cause of colitis in domestic cats. Despite a high prevalence, worldwide distribution, and lack of consistently effective drugs for treatment of the infection, the cellular mechanisms of T. foetus pathogenicity in the intestinal tract have not been examined. The aims of this study were to determine the pathogenic effect of feline T. foetus on porcine intestinal epithelial cells, the dependence of T. foetus pathogenicity on adhesion of T. foetus to the intestinal epithelium, and the identity of mediators responsible for these effects. Using an in vitro coculture approach to model feline T. foetus infection of the intestinal epithelium, these studies demonstrate that T. foetus promotes a direct contact-dependent activation of intestinal epithelial cell apoptosis signaling and progressive monolayer destruction. Moreover, these pathological effects were demonstrated to be largely dependent on T. foetus cell-associated cysteine protease activity. Finally, T. foetus cysteine proteases were identified as enabling cytopathic effects by promoting adhesion of T. foetus to the intestinal epithelium. The present studies are the first to examine the cellular mechanisms of pathogenicity of T. foetus toward the intestinal epithelium and support further investigation of the cysteine proteases as virulence factors in vivo and as potential therapeutic targets for ameliorating the pathological effects of intestinal trichomonosis.

Genetic predictors of cervical dysplasia in African American HIV-infected women: ACTG DACS 268

OBJECTIVE

To examine genome-wide associations in HIV-infected women with a history of cervical dysplasia compared with HIV-infected women with no history of abnormal Papanicolaou (Pap) tests.

DESIGN

Case-control study using data from women analyzed for the HIV Controllers Study and enrolled in HIV treatment-naïve studies in the AIDS Clinical Trials Group (ACTG).

METHODS

Genotyping utilized Illumina HumanHap 650 Y or 1MDuo platforms. After quality control and principal component analysis, ~610,000 significant single nucleotide polymorphisms (SNPs) were tested for association. Threshold for significance was P < 5 × 10(-8) for genome-wide associations.

RESULTS

No significant genomic association was observed between women with low-grade dysplasia and controls. The genome-wide association study (GWAS) analysis between women with high-grade dysplasia or invasive cervical cancer and normal controls identified significant SNPs. In the analyses limited to African American women, 11 SNPs were significantly associated with the development of high-grade dysplasia or cancer after correcting for multiple comparisons. The model using significant SNPs alone had improved accuracy in predicting high-grade dysplasia in African American women compared to the use of clinical data (area under the receiver operating characteristic curve for genetic and clinical model = 0.9 and 0.747, respectively).

CONCLUSIONS

These preliminary data serve as proof of concept that there may be a genetic predisposition to developing high-grade cervical dysplasia in African American HIV-infected women. Given the small sample size, the results need to be validated in a separate cohort.

Disruption of MDCK cell tight junctions by the free-living amoeba Naegleria fowleri

Naegleria fowleri is the aetiological agent of primary amoebic meningoencephalitis. This parasite invades its host by penetrating the olfactory mucosa. However, the mechanism of epithelium penetration is not well understood. In the present study, we evaluated the effect of N. fowleri trophozoites and the non-pathogenic Naegleria gruberi on Madin-Darby canine kidney (MDCK) tight junction proteins, including claudin-1, occludin and ZO-1, as well as on the actin cytoskeleton. Trophozoites from each of the free-living amoeba species were co-cultured with MDCK cells in a 1 : 1 ratio for 1, 3, 6 or 10 h. Light microscopy revealed that N. fowleri caused morphological changes as early as 3 h post-infection in an epithelial MDCK monolayer. Confocal microscopy analysis revealed that after 10 h of co-culture, N. fowleri trophozoites induced epithelial cell damage, which was characterized by changes in the actin apical ring and disruption of the ZO-1 and claudin-1 proteins but not occludin. Western blot assays revealed gradual degradation of ZO-1 and claudin-1 as early as 3 h post-infection. Likewise, there was a drop in transepithelial electrical resistance that resulted in increased epithelial permeability and facilitated the invasion of N. fowleri trophozoites by a paracellular route. In contrast, N. gruberi did not induce alterations in MDCK cells even at 10 h post-infection. Based on these results, we suggest that N. fowleri trophozoites disrupt epithelial monolayers, which could enable their penetration of the olfactory epithelium and subsequent invasion of the central nervous system.

Evaluation of Association between Vaginal Infections and High-Risk Human Papillomavirus Types in Female Sex Workers in Spain

Background. Infection with and persistence of high-risk human papillomavirus (HR-HPV) are the strongest risk factors for cervical cancer. In addition, other genital microorganisms may also be involved in the progression of HPV-associated lesions. Objetive. To evaluate the association of the vaginal microbiota (Candida spp., Trichomonas vaginalis, and bacterial vaginosis) with HR-HPV infection in Spanish female sex workers (FSWs). Methods. This cross-sectional study involved 208 (FSWs; age, 18-49 years) who visited a sexually transmitted infection (STI) information and prevention center (SERGAS) between January 2010 and December 2011. Face-to-face interviews were carried out. Cervical and vaginal samples were examined for human papillomavirus (HPV), Trichomonas vaginalis, Candida spp., and microorganisms related to bacterial vaginosis (BV). Results. HR-HPV was found to be significantly associated with BV in FSWs with positive results for HPV16-related types (31, 33, 35, and 52). T. vaginalis was isolated in FSWs with the following HR-HPVs: 18, 45, 66, and 68. Candida spp. were isolated only in FSWs with HPV 18-positive infection. Conclusion. We demonstrate a significant prevalence of HR-HPVs in FSWs with disturbances in the vaginal microbiota.

Trichomonas vaginalis: current understanding of host-parasite interactions

Trichomonas vaginalis is a sexually transmitted obligate extracellular parasite that colonizes the human urogenital tract. Despite being of critical importance to the parasite's survival relatively little is known about the mechanisms employed by T. vaginalis to establish an infection and thrive within its host. Several studies have focused on the interaction of the parasite with host cells and extracellular matrix, identifying multiple suspected T. vaginalis adhesins. However, with the exception of its surface lipophosphoglycan, the evidence supporting a role in adhesion is indirect or controversial for many candidate molecules. The availability of the T. vaginalis genome sequence paved the way for genomic analyses to search for proteins possibly involved in host-parasite interactions. Several proteomic analyses have also provided insight into surface, soluble and secreted proteins that may be involved in Trichomonas pathogenesis. Although the accumulation of molecular data allows for a more rational approach towards identifying drug targets and vaccine candidates for this medically important parasite, a continued effort is required to advance our understanding of its biology. In the present chapter, we review the current status of research aimed at understanding T. vaginalis pathogenesis. Applied experimental approaches, an overview of significant conclusions drawn from this research and future challenges are discussed.

Adherens junctions and pathogen entry

Epithelia are highly organised structures protecting underlying tissues against microbial pathogens. Epithelial morphogenesis and maintenance is mediated by cell-cell adhesion molecules organised in junctional complexes, such as the adherens junctions. The tight organisation of these complexes and their interactions with cellular factors render the epithelia impermeable to potential invaders. Nevertheless, pathogens have developed strategies to target, interact and manipulate junctional complexes, in order to disrupt or cross the epithelial barriers and cause infection. Bacteria, viruses and parasites access the junctional molecular components either directly, often taking advantage of physiological alterations in epithelial polarity, or indirectly, by delivering into cells molecular factors that destabilise junctional integrity. Importantly, microbial interactions with junctional components are instrumental not only to elucidate mechanisms of invasion, but also to unravel fundamental physiological properties of the epithelial barriers, at the cellular and tissular level.

Giardia disrupts the arrangement of tight, adherens and desmosomal junction proteins of intestinal cells

Giardia duodenalis is a parasitic protozoan that causes diarrhea and other symptoms which together constitute a disease known as giardiasis. Although the disease has been well defined, the mechanisms involving the establishment of the infection have not yet been fully elucidated. In this study, we show that after 24h of interaction between parasites and intestinal Caco-2 cells, there was an alteration of the paracellular permeability, as observed by an approximate 42% of reduction in the transepithelial electrical resistance and permeation to ruthenium red, which was concomitant with ultrastructural changes. Nevertheless, epithelium viability was not affected. We also demonstrate that there was no change in expression of junctional proteins (tight and adherens) but that the distribution of these proteins in Caco-2 cells after parasite adhesion was significantly altered, as observed via laser scanning confocal microscopy 3D reconstruction. The present work shows that adhesion of Giardia duodenalis trophozoites to intestinal cells in vitro induces disturbances of the tight, adherens and desmosomal junctions.

Modified Field stain - rapid viability test for Trichomonas vaginalis

AIMS

We previously reported that Modified Field Stain (MF) can be used as a rapid stain for diagnosis. In the present study we extend the observation to include the stain as an alternative method to assess viability of the cells.

METHODS AND RESULTS

Six isolates of Trichomonas vaginalis were used to assess the utility of the Modified Field stain as a rapid viability test for T. vaginalis and to compare with 0·4% Trypan Blue dye exclusion test in three conditions; normal in vitro culture growth using Hollander medium, lysed in distilled water and treated with metronidazole. MF stain showed similar growth profile pattern as Trypan Blue dye exclusion for identifying viable cells of T. vaginalis. Although, Trypan Blue dye exclusion test is ready made, rapid and widely used in laboratory as reliable viability assay, however, the limitation using Trypan Blue is the dye was unable to show internal morphological changes during the parasite's transition from being viable to non-viable. On day 3 where cultures peaked the correlation factor of both assays done to assess the viability of parasites harvested from the controls, metronidazole and distilled water treated parasites were more than 0·9 respectively.

CONCLUSIONS

This confirms that MF staining does not only record permanently the morphological changes and retain internal structural details but also provides a reliable and rapid viability assay for the parasites.

SIGNIFICANCE AND IMPACT OF THE STUDY

Therefore, in our study, Modified Field's stain may offer the researchers and laboratory technologists the opportunity to get the result on the same day and the most important thing is the ability to differentiate between viable and non-viable of T. vaginalis under three different conditions (normal culture, drug and distilled water condition). Modified Field's staining method enhanced the morphological identification of T. vaginalis compared to Trypan Blue dye exclusion.

Toxoplasma gondii down modulates cadherin expression in skeletal muscle cells inhibiting myogenesis

Background

Toxoplasma gondii belongs to a large and diverse group of obligate intracellular parasitic protozoa. Primary culture of mice skeletal muscle cells (SkMC) was employed as a model for experimental toxoplasmosis studies. The myogenesis of SkMC was reproduced in vitro and the ability of T. gondii tachyzoite forms to infect myoblasts and myotubes and its influence on SkMC myogenesis were analyzed.

Results

In this study we show that, after 24 h of interaction, myoblasts (61%) were more infected with T. gondii than myotubes (38%) and inhibition of myogenesis was about 75%. The role of adhesion molecules such as cadherin in this event was investigated. First, we demonstrate that cadherin localization was restricted to the contact areas between myocytes/myocytes and myocytes/myotubes during the myogenesis process. Immunofluorescence and immunoblotting analysis of parasite-host cell interaction showed a 54% reduction in cadherin expression at 24 h of infection. Concomitantly, a reduction in M-cadherin mRNA levels was observed after 3 and 24 h of T. gondii-host cell interaction.

Conclusions

These data suggest that T. gondii is able to down regulate M-cadherin expression, leading to molecular modifications in the host cell surface that interfere with membrane fusion and consequently affect the myogenesis process.

Tight junctions and viral entry

A wide variety of different viruses use tight junction (TJ) proteins in the course of infection and different mechanisms of pathogen–TJ interactions have been described; pathogens may induce the reorganization or degradation of distinct TJ proteins, reorganization of the cell cytoskeleton, activation of host-cell signaling pathways and/or use TJ proteins as receptors to enter host cells. Most recently, the TJ proteins claudin-1 and occludin have been identified as essential host factors for HCV entry. Furthermore, TJ protein occludin has been shown to play an important role in the species specificity of HCV infection. Recent data suggest that claudin-1 is a promising target for antiviral strategies. The aim of this article is to elucidate the impact of the interplay between pathogens and TJ proteins for pathogen–host interactions, summarize recent findings regarding the role of TJ proteins in HCV entry and highlight the relevance of TJ proteins for the development of novel antiviral strategies.

Current and future perspectives on the chemotherapy of the parasitic protozoa Trichomonas vaginalis and Entamoeba histolytica

Trichomonas vaginalis and Entamoeba histolytica are clinically important protozoa that affect humans. T. vaginalis produces sexually transmitted infections and E. histolytica is the causative agent of amebic dysentery. Metronidazole, a compound first used to treat T. vaginalis in 1959, is still the main drug used worldwide to treat these pathogens. It is essential to find new biochemical differences in these organisms that could be exploited to develop new antiprotozoal chemotherapeutics. Recent findings associated with T. vaginalis and E. histolytica biochemistry and host–pathogen interactions are surveyed. Knowledge concerning the biochemistry of these parasites is serving to form the foundation for the development of new approaches to control these important human pathogens.

Evolutionary and functional diversity of coronin proteins

This chapter discusses various aspects of coronin phylogeny, structure and function that are of specific interest. Two subfamilies of ancient coronins of unicellular pathogens such as Entamoeba, Trypanosoma, Leishmania and Acanthamoeba as well as of Plasmodium, Babesia, and Trichomonas are presented in the first two sections. Their coronins generally bind to F-actin and apparently are involved in proliferation, locomotion and phagocytosis. However, there are so far no studies addressing a putative role of coronin in the virulence of these pathogens. The following section delineates genetic anomalies like the chimeric coronin-fusion products with pelckstrin homology and gelsolin domains that are found in amoeba. Moreover, most nonvertebrate metazoa appear to encode CRN8, CRN9 and CRN7 representatives (for these coronin symbols see Chapter 2), but in e.g., Drosophila melanogaster and Caenorhabditis elegans a CRN9 is missing. The forth section deals with the evolutionary expansion of vertebrate coronins. Experimental data on the F-actin binding CRN2 of Xenopus (Xcoronin) including a Cdc42/Rac interactive binding (CRIB) motif that is also present in other members of the coronin protein family are discussed. Xenopus laevis represents a case for the expansion of the seven vertebrate coronins due to tetraploidization events. Other examples for a change in the number of coronin paralogs are zebrafish and birds, but (coronin) gene duplication events also occurred in unicellular protozoa. The fifth section of this chapter briefly summarizes three different cellular processes in which CRN4/CORO1A is involved, namely actin-binding, superoxide generation and Ca(2+)-signaling and refers to the largely unexplored mammalian coronins CRN5/CORO2A and CRN6/CORO2B, the latter binding to vinculin. The final section discusses how, by unveiling the aspects of coronin function in organisms reported so far, one can trace a remarkable evolution and diversity in their individual roles anticipating a rather complex and intricate involvement of coronins in a variety of cellular processes.

Trichomonas adhere and phagocytose sperm cells: adhesion seems to be a prominent stage during interaction

Tritrichomonas foetus and Trichomonas vaginalis are extracellular parasites of the urogenital tract of cattle and humans, respectively. They cause infertility and abortion, but there is no documented information on the susceptibility of bovine sperm cells to this cattle parasite. The aim of this present work was to study the effects provoked by T. foetus and T. vaginalis when in interaction with bovine and human sperm cells. The bovine and human spermatozoa were obtained from uninfected bulls and men, respectively, and were exposed to living trichomonads over different periods of time. Light microscopy, video microscopy, scanning, and transmission electron microscopy first revealed a tropism, then a close proximity followed by a tight adhesion between these two different cells. A decrease in the spermatozoa motility was observed as well intense semen agglutination. The adhesion between trichomonads to the sperm cell occurred either by the flagella or sperm head. Motile parasites were observed during the next 12 h, whereas sperm cells in contact with the parasites rapidly became immotile. The parasites were able to maintain the sperm cells attached to their cell surface, followed by phagocytosis. This process began with a tight membrane-membrane adhesion and the incorporation of the sperm cell within an intracellular vacuole. Afterwards, the sperm cell was gradually digested in lysosomes. Many trichomonads were injured and/or died on making contact with the spermatozoa possibly due to necrosis. Results from this study demonstrated that both T. foetus and T. vaginalis interact with sperm cells provoking damage and death of these reproductive cells. Differences in the behavior of both trichomonads were evident, showing that T. vaginalis was much more virulent than T. foetus. The possible role of trichomonads in reproductive failure is discussed.

Phagocytosis by Trichomonas vaginalis: new insights

BACKGROUND INFORMATION

The parasitic protozoan Trichomonas vaginalis is the causative agent of trichomoniasis, a sexually transmitted disease. The phagocytic activity of this parasite has not been completely elucidated. In order to better understand the mechanisms of trichomonal phagocytosis, we have studied the in vitro capacity of T. vaginalis to phagocytose and degrade Saccharomyces cerevisiae cells.

RESULTS AND CONCLUSIONS

To analyse the phagocytic ability and capacity, two isolates of T. vaginalis presenting different virulence grades were used. Complementary techniques, such as fluorescence microscopy, computer-based fluorescence analysis, scanning and transmission electron microscopy and the use of drugs that interfere with the actin microfilaments, were used in order to follow the behaviour of the actin cytoskeleton during phagocytosis of yeast cells by T. vaginalis. It was concluded that: (1) T. vaginalis changes its shape rapidly and engulfs the yeast cells, which are almost as large as the parasite; (2) long-term and fresh cultures are able to phagocytose, although the low-virulence strain JT demonstrated a lower activity when compared with the highly virulent T016 isolate; (3) the T016 strain exhibited an amoeboid morphology during the internalization of yeast cells in contrast with the JT strain; (4) attachment of yeast cells to the parasite occurs via the whole cell surface, including both anterior and recurrent flagella; (5) two forms of phagocytosis were observed: a 'sinking' process without any apparent participation of plasma membrane extensions and the classical phagocytosis where pseudopodia are extended toward the target cell; (6) the internalized S. cerevisiae are digested in lysosomes; (7) competitor sugars D-mannose or L-fucose inhibit the phagocytosis, and inhibition was 1.67 times higher in long-term cultured JT than that of the parasites from fresh isolate T016; (8) a thick layer of actin microfilaments was present underlying the plasma membrane, and especially in the pseudopodia and around the phagocytosed particles; (9) a dramatic change in the distribution pattern of fibrillar actin occurred during phagocytosis; (10) cytochalasin D depressed the phagocytosis; (11) a non-specific recognition and phagocytosis of yeast cells by T. vaginalis is mediated by a mannose receptor present on the parasite surface; (12) the phagocytic process may occur simultaneously during mitosis of the parasite.

The spermicidal and antitrichomonas activities of SSRI antidepressants

The study investigated spermicidal and antitrichomonas activities of selective serotonin reuptake inhibitor (SSRI) antidepressants with a view to generate new lead for development of dual-function spermicidal microbicides, which is an urgent global need. Fluoxetine, Sertraline, and Fluvoxamine exhibited both spermicidal and anti-STI (antitrichomonas) activities in vitro, whereas Paroxetine and Citalopram showed only the spermicidal activity. Fluoxetine exhibited better activity profile than the other antidepressant drugs with its spermicidal and antitrichomonas activities being comparable to that of the OTC contraceptive Nonoxynol-9. The non-detergent nature of Fluoxetine and a much lower spermicidal ED50 value (than N-9) may add considerably to its merit as a candidate for microbicidal contraceptive. Thus, the antidepressants exhibiting both spermicidal and antitrichomonas activities might provide useful lead for the development of novel, dual-function spermicidal contraceptives.