The effect of placental subfractions on Trypanosoma cruzi

Unnexins: Homologs of innexin proteins in Trypanosomatidae parasites

Large-pore channels, including those formed by connexin, pannexin, innexin proteins, are part of a broad family of plasma membrane channels found in vertebrates and invertebrates, which share topology features. Despite their relevance in parasitic diseases such as Chagas and malaria, it was unknown whether these large-pore channels are present in unicellular organisms. We identified 14 putative proteins in Trypanosomatidae parasites as presumptive homologs of innexin proteins. All proteins possess the canonical motif of the innexin family, a pentapeptide YYQWV, and 10 of them share a classical membrane topology of large-pore channels. A sequence similarity network analysis confirmed their closeness to innexin proteins. A bioinformatic model showed that a homolog of Trypanosoma cruzi (T. cruzi) could presumptively form a stable octamer channel with a highly positive electrostatic potential in the internal cavities and extracellular entrance due to the notable predominance of residues such as Arg or Lys. In vitro dye uptake assays showed that divalent cations-free solution increases YO-PRO-1 uptake and hyperosmotic stress increases DAPI uptake in epimastigotes of T. cruzi. Those effects were sensitive to probenecid. Furthermore, probenecid reduced the proliferation and transformation of T. cruzi. Moreover, probenecid or carbenoxolone increased the parasite sensitivity to antiparasitic drugs commonly used in therapy against Chagas. Our study suggests the existence of innexin homologs in unicellular organisms, which could be protein subunits of new large-pore channels in unicellular organisms.

Congenital Chagas disease as an ecological model of interactions between Trypanosoma cruzi parasites, pregnant women, placenta and fetuses

The aim of this paper is to discuss the main ecological interactions between the parasite Trypanosoma cruzi and its hosts, the mother and the fetus, leading to the transmission and development of congenital Chagas disease. One or several infecting strains of T. cruzi (with specific features) interact with: (i) the immune system of a pregnant woman whom responses depend on genetic and environmental factors, (ii) the placenta harboring its own defenses, and, finally, (iii) the fetal immune system displaying responses also susceptible to be modulated by maternal and environmental factors, as well as his own genetic background which is different from her mother. The severity of congenital Chagas disease depends on the magnitude of such final responses. The paper is mainly based on human data, but integrates also complementary observations obtained in experimental infections. It also focuses on important gaps in our knowledge of this congenital infection, such as the role of parasite diversity vs host genetic factors, as well as that of the maternal and placental microbiomes and the microbiome acquisition by infant in the control of infection. Investigations on these topics are needed in order to improve the programs aiming to diagnose, manage and control congenital Chagas disease.

Mechanism of Trypanosoma cruzi Placenta Invasion and Infection: The Use of Human Chorionic Villi Explants

Congenital Chagas disease, a neglected tropical disease, endemic in Latin America, is associated with premature labor and miscarriage. During vertical transmission the parasite Trypanosoma cruzi (T. cruzi) crosses the placental barrier. However, the exact mechanism of the placental infection remains unclear. We review the congenital transmission of T. cruzi, particularly the role of possible local placental factors that contribute to the vertical transmission of the parasite. Additionally, we analyze the different methods available for studying the congenital transmission of the parasite. In that context, the ex vivo infection with T. cruzi trypomastigotes of human placental chorionic villi constitutes an excellent tool for studying parasite infection strategies as well as possible local antiparasitic mechanisms.

Langmuir films from human placental membranes: preparation, rheology, transfer to alkylated glasses, and sigmoidal kinetics of alkaline phosphatase in the resultant Langmuir-Blodgett film

In the present study, we studied the activity of human placental alkaline phosphatase (PLAP) constraint in a planar surface in controlled molecular packing conditions. For the first time, Langmuir films (LFs) were prepared by the spreading of purified placental membranes (PPM) on the air-water interface and their stability and rheological properties were studied. LFs exhibited a collapse pressure pi(C) = 48 mN/m, hysteresis during the compression-decompression cycle (C-D), indicating a plastic deformation, and a compressibility modulus (K) compatible with liquid-expanded phases. A phase transition point appeared at pi(T) = 28 mN/m and, following successive C-D, it moved toward lower surface areas and higher K, suggesting the lost of some non-PLAP proteins as components of vesicles that might protrude from the monolayer (confirmed by combining lipid/protein molar ratio analysis, PAGE-SDS and V(max)). LFs were transferred at 35 mN/m to alkylated glasses to obtain Langmuir-Blodgett films (LB(35)) the stability of which was confirmed by AFM. The kinetics of p-nitrophenyl phosphate (pNPP) hydrolysis at 37 degrees C catalyzed by PPM was Michaelian and exhibited the thermostability at 60 degrees C typical of PLAP. In LB(35), PLAP exhibited a sigmoidal kinetics which resembled the behavior of the partially metalated enzyme but might become from a cross-talk between protein and membrane structures.

Molecular diagnosis and treatment monitoring of congenital transmission of Trypanosoma cruzi to twins of a triplet delivery

Congenital transmission of Trypanosoma cruzi was diagnosed in 2 triplets born to a triamniotic bichorionic delivery. Only the sisters sharing the placenta became infected, as diagnosed by microhematocrit and/or polymerase chain reaction of 3 parasite targets. The neonates' parasitologic response to benznidazole was monitored. Molecular strategies allowed genotyping lineage IId and identical minicircle signatures in both triplets, showing they harbored the same maternal parasite populations.

Trypanosoma cruzi in non-human primates with a history of stillbirths: a retrospective study (Papio hamadryas spp.) and case report (Macaca fascicularis)

BACKGROUND

Congenital transmission of Trypanosoma cruzi has been described in humans and experimental work has been conducted with mice, but not with non-human primates (NHPs).

METHODS

We conducted a retrospective study of female baboons (Papio hamadryas spp.) naturally seropositive or seronegative for T. cruzi with history of fetal loss, and we report a stillbirth in a cynomolgus macaque (Macaca fascicularis) with placental T. cruzi amastigotes.

RESULTS

There were no differences in menstrual cycle parameters and the number of fetal losses between seropositive and seronegative baboons with history of fetal loss. The amount of parasite DNA detected using quantitative polymerase chain reaction (Q-PCR) in M. fascicularis placenta was within the range detected in infected baboon tissues.

CONCLUSIONS

There is no evidence that chronic maternal T. cruzi infection causes fetal loss in baboons. Q-PCR is a useful diagnostic tool to study archived NHP placentas.

Trypanosoma cruzi: productive infection is not allowed by chorionic villous explant from normal human placenta in vitro

We hypothesize that a sustained infection of Trypanosoma cruzi into placental tissue might be diminished. Human placental chorionic villi and VERO cells as controls were co-cultured with T. cruzi. Parasites occupied 0.0137% at 3h, 0.0224% (24h), and 0.0572% (72 h) of the total chorionic villi area analyzed and some few placental samples were negative to parasite DNA, whereas 52% of VERO cells were infected at 3h and parasites occupied 0.57%, at 24h the parasite area was of 2.78% and at 72 h was of 3.32%. There were no live parasites in placenta-T. cruzi culture media at 72 h of co-culture. There were significantly increased dead parasites when T. cruzi was treated with unheated culture media coming from placental explants and fewer dead parasites when pre-heated culture media were employed.

CONCLUSION

Low productive infection by T. cruzi into placental tissue associated with no viable parasites in the culture media partially due to placental thermo labile substances.

Role of placental alkaline phosphatase in the internalization of trypomatigotes of Trypanosoma cruzi into HEp2 cells

BACKGROUND

In vitro, Trypanosoma cruzi invades a wide variety of mammalian cells by an unique process that is still poorly understood. Trypomastigotes adhere to specific receptors on the outer membrane of host cells before intracellular invasion, causing calcium ion mobilization and rearrangement of host cell microfilaments.

OBJECTIVE

To test if placental alkaline phosphatase (PLAP), a trophoblast plasma membrane protein anchored by a glycosylphosphatidylinositol molecule, is involved in the transplacental transmission of this parasite.

METHOD

We cultured HEp2 cells with the parasite and studied PLAP and actin microfilaments. The results were correlated with invasion rate.

RESULTS

Human HEp2 tumour cells express PLAP. HEp2 cells infected with trypomastigotes showed alteration in their alkaline phosphatase activity and a different pattern of actin organization, compared to control cells. Perturbation of PLAP from HEp2 cells before infection with T. cruzi trypomastigotes decreased the invasion rate.

CONCLUSION

Placental alkaline phosphatase could be involved in the internalization of T. cruzi into HEp2 cells, via activation of tyrosine kinase and rearrangement of actin microfilaments.

Acute Trypanosoma cruzi infection in mouse induces infertility or placental parasite invasion and ischemic necrosis associated with massive fetal loss

Pathogens may impair reproduction in association or not with congenital infections. We have investigated the effect of acute infection with Trypanosoma cruzi, the protozoan agent of Chagas' disease in Latin America, on reproduction of mice. Although mating of infected mice occurred at a normal rate, 80% of them did not become gravid. In the few gravid infected mice, implantation numbers were as in uninfected control mice, but 28% of fetuses resorbed. Such infertility and early fetal losses were significantly associated with high maternal parasitemia. The remaining fetuses presented with reduced weights and all died later in gestation or within 48 hours after birth. Several organs of these fetuses were infiltrated by polynuclear cells and presented ischemic necrosis but did not harbor T. cruzi parasites, discarding congenital infection as the cause of mortality. However, surprisingly, the deciduas were massively invaded by T. cruzi parasites, harboring 125-fold more amastigotes than the maternal heart or other placental tissues. Parasites were significantly more numerous in the placentas of dead fetuses. In addition, placentas contained inflammatory infiltrates and displayed ischemic necrosis, fibrin deposits, and vascular thromboses. These results show that acute T. cruzi infection totally impairs reproduction in mice through inducing infertility or fetal-neonatal losses in association with placental parasite invasion and ischemic necrosis.