Trophoblast cells primed with VIP enhance monocyte 1 migration and apoptotic cell clearance through αvβ3 integrin portal formation in a model of maternal-placental interaction

D. PAPARINI, E. GRASSO, G. CALO, D. VOTA, V.HAUK, R. RAMHORST, C. PÉREZ LEIRÓS

MOLECULAR HUMAN REPRODUCTION.

OXFORD UNIV PRESS

Lugar: Oxford; Año: 2015 vol. 21 p. 933 - 941

1360-9947

study hypothesis: Is apoptotic cell phagocytosis by monocytes modulated by pathways elicited by vasoactive intestinal peptide (VIP)action on trophoblast?study finding: Targeting trophoblast cells with VIP induces monocyte migration, polarization to anti-inflammatory phenotypes and apoptotictrophoblast cell clearance which involves increased avb3 integrin expression on phagocytic cells and binding to thrombospondin 1.what is known already: Monocytes recruited to the maternal?placental interface interact with trophoblast cells and differentiate toalternatively activated macrophages involved in the silent clearance of apoptotic cells. Vasoactive intestinal peptide (VIP) is an immunomodulatorypolypeptide synthesized at the human placenta that can target both trophoblast cells and monocytes/macrophages. Integrin avb3 and thrombospondin1 are involved in the formation of a phagocytic portal for the immunosuppressant clearance of apoptotic cells.study design, samples/materials, methods: This is a laboratory-based study studying monocytes isolated from peripheralblood of healthy women (n ¼ 33) and their interaction in vitro with first trimester trophoblast cell lines. Peripheral blood monocytes were isolatedfrom healthy volunteers by Percoll gradient and tested in co-culture settings with first trimester trophoblast cell lines (Swan 71 and HTR8) or withtrophoblast cell conditioned media obtained in the presence or absence of 10 or 100 nM VIP. The effect of VIP-conditioned media on monocytemigration was assessed through transwell systems and monocyte/macrophage phenotype was determined by flow cytometry. Phagocytosis ofapoptotic cells and the mechanisms involved in phagocytic portal formation were assessed byflowcytometry, confocal microscopy, immunologicalblockade and RT?PCR.main results and the role of chance: Exposing cells to 100 nM VIP increased the migration of monocytes toward trophoblastcell conditioned media (VIP conditioned medium) (P , 0.05 versus conditioned media from cells not exposed to VIP) and contributed to themonocytes acquiring an anti-inflammatory profile with increased CD39 and IL-10 expression (P , 0.05). Phagocytosis of apoptotic trophoblastcells by monocytes and monocyte-differentiated macrophages was increased by VIP conditioned medium (P , 0.05 versus media conditioned inthe absence of VIP or direct addition of 100 nM VIP). The boosting effect of VIP conditioned medium on phagocytosis involved increased expressionand re-localization of avb3 integrin on phagocytic cells along with enhanced expression of thrombospondin 1 on trophoblast cells.limitations, reasons for caution: The conclusions are based on in vitro experiments with monocytes drawn from peripheralblood of healthy individuals and trophoblast cell lines and we were unable to ascertain that these mechanisms operate similarly in vivo.We cannotrule outa differential behavior of either trophoblast cells targeted in vivo with VIP, or primary cultures of first trimester trophoblast cells assayedin vitro.