Abstract
BackgroundThe interest in the mechanisms involved in Toxoplasma gondii lipid acquisition has steadily increased during the past few decades, but it remains not completely understood. Here, we investigated the biogenesis and the fate of lipid droplets (LD) of skeletal muscle cells (SkMC) during their interaction with T. gondii by confocal and electron microscopy. We also evaluated whether infected SkMC modulates the production of prostaglandin E2 (PGE2), cytokines interleukin-12 (IL-12) and interferon-gamma (INF-g), and also the cyclooxygenase-2 (COX-2) gene induction.MethodsPrimary culture of skeletal muscle cells were infected with tachyzoites of T. gondii and analysed by confocal microscopy for observation of LD. Ultrastructural cytochemistry was also used for lipid and sarcoplasmatic reticulum (SR) detection. Dosage of cytokines (IL-12 and INF-g) by ELISA technique and enzyme-linked immunoassay (EIA) for PGE2 measurement were employed. The COX-2 gene expression analysis was performed by real time reverse transcriptase polymerase chain reaction (qRT-PCR).ResultsWe demonstrated that T. gondii infection of SkMC leads to increase in LD number and area in a time course dependent manner. Moreover, the ultrastructural analysis demonstrated that SR and LD are in direct contact with parasitophorous vacuole membrane (PVM), within the vacuolar matrix, around it and interacting directly with the membrane of parasite, indicating that LD are recruited and deliver their content inside the parasitophorous vacuole (PV) in T. gondii-infected SkMC. We also observed a positive modulation of the production of IL-12 and IFN-g, increase of COX-2 mRNA levels in the first hour of T. gondii-SkMC interaction and an increase of prostaglandin E2 (PGE2) synthesis from 6 h up to 48 h of infection.ConclusionsTaken together, the close association between SR and LD with PV could represent a source of lipids as well as other nutrients for the parasite survival, and together with the increased levels of IL-12, INF-g and inflammatory indicators PGE2 and COX-2 might contribute to the establishment and maintenance of chronic phase of the T. gondii infection in muscle cell.
Highlights
The interest in the mechanisms involved in Toxoplasma gondii lipid acquisition has steadily increased during the past few decades, but it remains not completely understood
We have investigated the role of lipid droplets (LD) biogenesis and their interaction with parasitophorous vacuole (PV), the modulation of IL-12 and interferon gamma (IFN-g) secretion as well as COX-2 gene expression and prostaglandin E2 (PGE2) synthesis, during T. gondii-skeletal muscle cells (SkMC) infection in order to better understand the survival mechanisms of Toxoplasma in muscle cells
It was possible to demonstrate by use of BODIPY in representative images at 24 h (Figure 3A and B) and 48 h (Figure 3C, D) an increase of LD in infected SkMC, which was time-dependent when analyzed during a period of 6 h to 48 h (Figure 4)
Summary
The interest in the mechanisms involved in Toxoplasma gondii lipid acquisition has steadily increased during the past few decades, but it remains not completely understood. T. gondii is an obligatory intracellular protozoan parasite that resides within a PV, which fails to fuse with host organelles from the endocytic pathway [1,2]. This condition potentially deprives parasites of a large source of nutrients from the host endocytic and exocytic system [3]. The mechanisms involved in T. gondii lipid acquisition are a matter of interest and are still not completely understood. T. gondii infection leads to increased receptormediated cholesterol endocytosis by the low-density lipoprotein (LDL) pathway [1,7]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
