Sabapatha A, Gercel-Taylor C, Taylor DD. Specific Isolation of Placenta-Derived Exosomes from the Circulation of Pregnant Women and Their Immunoregulatory Consequences.
Am J Reprod Immunol 2006;
56:345-55. [PMID:
17076679 DOI:
10.1111/j.1600-0897.2006.00435.x]
[Citation(s) in RCA: 244] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
PROBLEM
One immunoregulatory pathway receiving little attention is placental exosome release. In normal pregnancy, as factors linked with early immunomodulation decline, placental exosomes become critical in modulating T-cell activation, suppressing effector T cells by enhancing lymphocyte apoptosis and CD3-zeta loss.
METHOD OF STUDY
Placental exosomes were specifically isolated from the maternal peripheral circulation by a chromatographic/immunosorbent procedure. Exosomal suppression of T-cell signaling molecules on unfractionated T cells and T subsets was analyzed by Western immunoblot. The role of Fas ligand (FasL) was defined by use of Fas-blocking antibody.
RESULTS
While exosomes of lymphoid origin could be demonstrated in all women, placenta-derived exosomes were only identified in pregnant patients. Placental exosomes suppressed T-cell expression of CD3-zeta and JAK3, while inducing SOCS-2. This downregulation of CD3-zeta was partially reversed by pre-incubating T cells with ZB4 antibody. Using T subsets, the level of CD3-zeta on CD8+ cells was inhibited 1.43-fold more than in CD4+ cells. On CD4+ CD25+ cells, CD3-zeta was not significantly inhibited.
CONCLUSION
Placental exosomes suppressed T-cell signaling components; however, while exosomal FasL is an important contributor, it does not appear to be the sole mediator. The additional expression of PD-L1 may explain immunoregulatory consequences of exosomes with low or absent FasL.
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