Automated quantitation of cell-mediated HIV type 1 infection of human syncytiotrophoblast cells by fluorescence in situ hybridization and laser scanning cytometry

In vitro study on hepatitis B virus infecting human choriocarcinoma JEG3 cells and its mechanism

AIM

To build a hepatitis B virus (HBV)-infected human trophoblast cell model in vitro and determine the mechanism of intrauterine HBV infection.

METHODS

Serum from hepatitis B-infected patients containing HBV DNA >10(9) was drawn, subsequently inoculated into human trophoblast cells in vitro (JEG3) and passage-cultured. The supernatants and intracellular HBV viral load of inoculated cells were tested by real-time PCR, and HBV DNA was determined by Southern blot.

RESULTS

From inoculation of the 1st passage JEG3 cells, the supernatant viral load of the 1st passage was seen increasing over time, which peaked at 120 h, whereas the HBV viral load was seen decreasing gradually in subsequent passages, and tested negative after the 6th passage. In addition, infected cells of HBV DNA were tested by Southern blot, and showed continual expression in the subsequent cell passages 1-5 while passage 6 was negative. HBsAg was tested as positive from different passages 1-5, and its concentration was also seen decreasing with each subsequent passage cultured until the 6th passage when it tested negative.

CONCLUSION

HBV could infect human trophoblast cells (JEG3) in vitro, and it showed continual expression in subsequent cell passages 1-5.

Differential expression of RDC1/CXCR7 in the human placenta

INTRODUCTION

Chemokine receptor expression by human trophoblast and other placental cells have important implications for understanding the regulation of placental growth, development, and their role in maternofetal HIV transmission. CXCR7, now a deorphanized G protein coupled receptor that has been recently shown to bind to the ligands ITAC and CXCL12 has been proposed to act as a co-receptor for HIV-1, HIV-2, and SIV strains. The differential expression of CXCR7 in the human placenta is not yet reported.

METHODS

The expression of CXCR7 was studied in 45 different human placental tissues, of which 20 were from early placental tissues (8-10 week old) obtained from medically terminated pregnancies and 25 were placenta from normal term deliveries.

RESULTS

Immunohistochemistry and RT-PCR analysis revealed a greater expression of CXCR7 in term human placenta as compared to the early stage. This was further confirmed by real-time PCR.

CONCLUSION

Our study reveals, for the first time, the differential expression of CXCR7 in early (8-10 weeks) and term human placenta. The precise role of CXCR7 in the human placenta needs to be determined. HIV vertical transmission is reported to occur mainly during the end stages of pregnancy. Our finding of increased CXCR7 expression in the term human placenta therefore warrants future studies to assess its role in the vertical transmission of HIV-1.

Transcytosis of Human immunodeficiency virus 1 across the placenta is enhanced by treatment with tumour necrosis factor alpha

The human placenta is relatively resistant to Human immunodeficiency virus 1 (HIV-1), but obstetric complications associated with inflammatory processes, including chorioamnionitis and spontaneous preterm delivery, are associated with increased rates of vertical transmission. It was hypothesized that the pro-inflammatory mediator tumour necrosis factor alpha (TNF-alpha), which promotes HIV-1 transmission across endothelial membranes, increases HIV-1 transmission across the placenta. Flow cytometry and immunostaining studies were performed, which demonstrated that the HIV-1 receptors CD4, CCR5 and CXCR4 were not expressed by villous trophoblast cells. Consequently, primary villous trophoblast cells were not infected with cell-free HIV-1 isolates, as measured by in situ PCR and quantitative PCR, but villous trophoblast cells were infected by HIV-1-infected peripheral blood mononuclear cells (PBMC). HIV-1 from infected PBMC was rapidly transported across confluent transformed trophoblast cell monolayers by transcytosis, and TNF-alpha significantly upregulated transcytosis of HIV-1 across the trophoblast layer without disrupting cell viability or confluency. Inhibitors of TNF-alpha (antibodies against TNF-alpha and TNF-alpha receptors) and an anti-inflammatory drug (tenidap) significantly reduced transcytosis rates. It was concluded that the villous trophoblast is resistant to infection by cell-free HIV-1 but susceptible to transcytosis of HIV-1 from infected PBMC, and inflammatory mediators such as TNF-alpha may play a critical role in promoting maternal-fetal transmission of HIV-1.

Uptake of hepatitis B virus into choriocarcinoma cells in the presence of proinflammatory cytokine tumor necrosis factor-alpha

OBJECTIVE

The aim of this study was to establish an in vitro experimental model that mimics the interaction of hepatitis B virus (HBV) and the trophoblastic barrier.

STUDY DESIGN

The barrier was represented by choriocarcinoma cell line, JAR cells, which were incubated with HBV in the presence or absence of tumor necrosis factor-alpha (TNF-alpha). At 12-hour intervals after a 24-hour incubation, the infection efficiency was examined by enzyme-linked immunosorbent assay of culture supernatants, immunohistochemistry of cell slides, Western blotting of cell lysates, polymerase chain reaction amplification for viral DNA of infected cells, and transmission electron microscopy for HBsAg particles in infected cells.

RESULTS

In the absence of TNF-alpha, many JAR cell colonies showed a negative or punctate positive pattern after incubation with HBV. But when JAR cells were pretreated with TNF-alpha before cocultured with HBV, the infection was greatly enhanced, whereas the differences observed between the various time points in the second series of experiments did not reach a statistically significant level.

CONCLUSION

JAR cells can support HBV infection in the presence of TNF-alpha. Our in vitro system provides key basis on further study reflecting mechanism of in vivo HBV intrauterine infection and transfer.

Clinical applications of laser scanning cytometry

This study reviews existing and potential clinical applications of laser scanning cytometry (LSC) and outlines possible future developments. LSC provides a technology for solid phase cytometry. Fluorochrome-labeled specimens are immobilized on microscopic slides that are placed on a conventional epifluorescence microscope and analyzed by one or two lasers. Data comparable to flow cytometry are generated. In addition, the position of each event is recorded, a feature that allows relocalization and visualization of each measured event. The major advantage of LSC compared with other cytometric methods is the combination of two features: (a) the minimal clinical sample volume needed and (b) the connection of fluorescence data and morphological information for the measured event. Since the introduction of LSC, numerous methods have been established for the analysis of cells, cellular compartments, and tissues. Although most cytometric methods use only two or three colors, the characterization of specimens with up to five fluorochromes is possible. Most clinical applications have been designed to determine ploidy and immunophenotype; other applications include analyses of tissue biopsies and sections, fluorescence in situ hybridization, and the combination of vital and nonvital information on a single-cell basis. With the currently available assays, LSC has proven its wide spectrum of clinical applicability in slide-based cytometry and can be introduced as a standard technology in multiple clinical settings.