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P21 is a protein secreted by all forms of Trypanosoma cruzi (T. cruzi) with recognized biological activities determined in studies using the recombinant form of the protein. In our recent study, we found that the ablation of P21 gene decreased Y strain axenic epimastigotes multiplication and increased intracellular replication of amastigotes in HeLa cells infected with metacyclic trypomastigotes. In the present study, we investigated the effect of P21 in vitro using C2C12 cell lines infected with tissue culture-derived trypomastigotes (TCT) of wild-type and P21 knockout (TcP21-/-) Y strain, and in vivo using an experimental model of T. cruzi infection in BALB/c mice. Our in-vitro results showed a significant decrease in the host cell invasion rate by TcP21-/- parasites as measured by Giemsa staining and cell count in bright light microscope. Quantitative polymerase chain reaction (qPCR) analysis showed that TcP21-/- parasites multiplied intracellularly to a higher extent than the scrambled parasites at 72h post-infection. In addition, we observed a higher egress of TcP21-/- trypomastigotes from C2C12 cells at 144h and 168h post-infection. Mice infected with Y strain TcP21-/- trypomastigotes displayed higher systemic parasitemia, heart tissue parasite burden, and several histopathological alterations in heart tissues compared to control animals infected with scrambled parasites. Therewith, we propose that P21 is important in the host-pathogen interaction during invasion, cell multiplication, and egress, and may be part of the mechanism that controls parasitism and promotes chronic infection without patent systemic parasitemia. [ABSTRACT FROM AUTHOR]

Introduction: Toxoplasma gondii is the etiologic agent of toxoplasmosis, a disease that affects about one-third of the human population. Most infected individuals are asymptomatic, but severe cases can occur such as in congenital transmission, which can be aggravated in individuals infected with other pathogens, such as HIV-positive pregnant women. However, it is unknown whether infection by other pathogens, such as Trypanosoma cruzi, the etiologic agent of Chagas disease, as well as one of its proteins, P21, could aggravate T. gondii infection. Methods: In this sense, we aimed to investigate the impact of T. cruzi and recombinant P21 (rP21) on T. gondii infection in BeWo cells and human placental explants. Results: Our results showed that T. cruzi infection, as well as rP21, increases invasion and decreases intracellular proliferation of T. gondii in BeWo cells. The increase in invasion promoted by rP21 is dependent on its binding to CXCR4 and the actin cytoskeleton polymerization, while the decrease in proliferation is due to an arrest in the S/M phase in the parasite cell cycle, as well as interleukin (IL)-6 upregulation and IL-8 downmodulation. On the other hand, in human placental villi, rP21 can either increase or decrease T. gondii proliferation, whereas T. cruzi infection increases T. gondii proliferation. This increase can be explained by the induction of an anti-inflammatory environment through an increase in IL-4 and a decrease in IL-6, IL-8, macrophage migration inhibitory factor (MIF), and tumor necrosis factor (TNF)-a production. Discussion: In conclusion, in situations of coinfection, the presence of T. cruzi may favor the congenital transmission of T. gondii, highlighting the importance of neonatal screening for both diseases, as well as the importance of studies with P21 as a future therapeutic target for the treatment of Chagas disease, since it can also favor T. gondii infection. [ABSTRACT FROM AUTHOR]

Abstract: We examined whether the expression of Ssp-4-related carbohydrate epitopes defined by monoclonal antibodies 1D9 and 2B7 was related to cell invasion by Trypanosoma cruzi amastigotes from different isolates and whether the highest expression of the epitope defined by MAb 1D9 would confer greater infectivity. Confocal microscopy showed that both epitopes localize to the membrane of amastigotes from 569, 588, 573, 587 and SC2005 isolates, similar to the G isolate, whereas the CL isolate showed a punctate and diffuse staining. Flow cytometry revealed inter- and intra-isolate variable expression of these epitopes. Apart from the lower expression of MAb 2B7 epitope by intracellular amastigotes of the SC2005 isolate, amastigotes from chagasic patient isolates expressed both epitopes similar to the G isolate, in contrast to CL isolate, that showed lower expression of both epitopes. MAb 1D9 did not react with CL isolate on immunoblots and reacted poorly with 588 and 587 parasites. MAb 2B7 preferentially reacted with an epitope on an 84kDa component in G and 573 isolates. Invasion assays revealed that despite the fact that amastigotes from chagasic patient isolates displayed high levels of the epitope defined by MAb 1D9, only isolate 588 invaded host cells in levels comparable to that of isolate G. Both MAbs specifically inhibited cell invasion by G and 588, but not CL. These results suggested that the highest expression of MAb 1D9 epitope was not sufficient to confer higher infectivity on the isolate, and besides the two epitopes, other factors may modulate the invasiveness of extracellular amastigotes from the different isolates. [Copyright &y& Elsevier]