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Opsonization of apoptotic cells by autologous iC3b facilitates clearance by immature dendritic cells, down-regulates DR and CD86, and up-regulates CC chemokine receptor 7.

Verbovetski I, Bychkov H, Trahtemberg U, Shapira I, Hareuveni M, Ben-Tal O, Kutikov I, Gill O, Mevorach D - J. Exp. Med. (2002)

Bottom Line: A significant increase (P < 0.001) in the amount of cleared apoptotic cells was seen at low ratios.In addition, iDC maturation responses to CD40L and lipopolysaccharide were significantly inhibited.We conclude that opsonization of apoptotic cells by iC3b induces tolerant iDCs that are able to migrate to lymph nodes.

View Article: PubMed Central - PubMed

Affiliation: The Laboratory for Cellular and Molecular Immunology, Rheumatology Unit, Department of Medicine, Hadassah Hospital and the Hebrew University. Sourasky Medical Center, Jerusalem 91120, Israel.

ABSTRACT
Immature dendritic cells (iDCs) do not mature after uptake of apoptotic cells and may play a role in the induction of peripheral tolerance to self antigens derived from apoptotic material. The integrins, alphavbeta3, alphavbeta5, and the scavenger receptor, CD36, have been shown to mediate uptake of apoptotic cells by iDCs. However, it is not known whether the complement system, also takes part in this process. In this study we investigated the ability of iDCs to bind to apoptotic cells opsonized by iC3b. Monocyte-derived dendritic cells were offered apoptotic Jurkat cells opsonized by autologous iC3b and labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanineperchlorate. A significant increase (P < 0.001) in the amount of cleared apoptotic cells was seen at low ratios. Despite increased efficiency of uptake, interaction between iC3b-opsonized apoptotic cells and iDCs down-regulated the expression of major histocompatibility complex class II, CD86, CC chemokine receptor (CCR)2, CCR5, and beta2-integrins (P < 0.001), and up-regulated expression of CCR7 (P < 0.001). In addition, iDC maturation responses to CD40L and lipopolysaccharide were significantly inhibited. We conclude that opsonization of apoptotic cells by iC3b induces tolerant iDCs that are able to migrate to lymph nodes.

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CCR7 is expressed on iDCs after interaction with iC3b-opsonized apoptotic cells. iDCs were stained for the expression of chemokines receptors (bold lines), CCR2, CCR5, and CCR7 and compared with iDCs that were exposed to apoptotic cells (solid lines). On day 6, iDCs stained for CCR2 and CCR5 but not for CCR7. Upon exposure to opsonized apoptotic cells marked down-regulation of CCR2 and CCR5 was observed (median fluorescences were down-regulated (from 9.14 to 1.88, and from 21 to 1.55, respectively, P < 0.001). In contrast, median fluorescent of CCR7 was up-regulated from 3.31 to 6.92 (P = 0.001). Representative of four experiments. Range of up-regulation of CCR7, 60–300% increase.
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fig5: CCR7 is expressed on iDCs after interaction with iC3b-opsonized apoptotic cells. iDCs were stained for the expression of chemokines receptors (bold lines), CCR2, CCR5, and CCR7 and compared with iDCs that were exposed to apoptotic cells (solid lines). On day 6, iDCs stained for CCR2 and CCR5 but not for CCR7. Upon exposure to opsonized apoptotic cells marked down-regulation of CCR2 and CCR5 was observed (median fluorescences were down-regulated (from 9.14 to 1.88, and from 21 to 1.55, respectively, P < 0.001). In contrast, median fluorescent of CCR7 was up-regulated from 3.31 to 6.92 (P = 0.001). Representative of four experiments. Range of up-regulation of CCR7, 60–300% increase.

Mentions: We further strove to determine whether the down-regulation of maturation molecules such as CD86, CD83, and MHC class II was linked to the absence CCR7-mediated migration to lymph nodes. We were surprised to see, as shown in Fig. 5 , that after interaction with autologous iC3b-opsonized apoptotic Jurkat cells, iDCs demonstrated mild but significant up-regulation in the expression of CCR7 but down-regulation of CCR2 or CCR5. Phagocytosis of latex beads did not up-regulate the expression of CCR7 as median fluorescence was 3.66± 0.8 in iDCs and 3.88± 0.92 after phagocytosis of latex beads (three experiments).


Opsonization of apoptotic cells by autologous iC3b facilitates clearance by immature dendritic cells, down-regulates DR and CD86, and up-regulates CC chemokine receptor 7.

Verbovetski I, Bychkov H, Trahtemberg U, Shapira I, Hareuveni M, Ben-Tal O, Kutikov I, Gill O, Mevorach D - J. Exp. Med. (2002)

CCR7 is expressed on iDCs after interaction with iC3b-opsonized apoptotic cells. iDCs were stained for the expression of chemokines receptors (bold lines), CCR2, CCR5, and CCR7 and compared with iDCs that were exposed to apoptotic cells (solid lines). On day 6, iDCs stained for CCR2 and CCR5 but not for CCR7. Upon exposure to opsonized apoptotic cells marked down-regulation of CCR2 and CCR5 was observed (median fluorescences were down-regulated (from 9.14 to 1.88, and from 21 to 1.55, respectively, P < 0.001). In contrast, median fluorescent of CCR7 was up-regulated from 3.31 to 6.92 (P = 0.001). Representative of four experiments. Range of up-regulation of CCR7, 60–300% increase.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2196062&req=5

fig5: CCR7 is expressed on iDCs after interaction with iC3b-opsonized apoptotic cells. iDCs were stained for the expression of chemokines receptors (bold lines), CCR2, CCR5, and CCR7 and compared with iDCs that were exposed to apoptotic cells (solid lines). On day 6, iDCs stained for CCR2 and CCR5 but not for CCR7. Upon exposure to opsonized apoptotic cells marked down-regulation of CCR2 and CCR5 was observed (median fluorescences were down-regulated (from 9.14 to 1.88, and from 21 to 1.55, respectively, P < 0.001). In contrast, median fluorescent of CCR7 was up-regulated from 3.31 to 6.92 (P = 0.001). Representative of four experiments. Range of up-regulation of CCR7, 60–300% increase.
Mentions: We further strove to determine whether the down-regulation of maturation molecules such as CD86, CD83, and MHC class II was linked to the absence CCR7-mediated migration to lymph nodes. We were surprised to see, as shown in Fig. 5 , that after interaction with autologous iC3b-opsonized apoptotic Jurkat cells, iDCs demonstrated mild but significant up-regulation in the expression of CCR7 but down-regulation of CCR2 or CCR5. Phagocytosis of latex beads did not up-regulate the expression of CCR7 as median fluorescence was 3.66± 0.8 in iDCs and 3.88± 0.92 after phagocytosis of latex beads (three experiments).

Bottom Line: A significant increase (P < 0.001) in the amount of cleared apoptotic cells was seen at low ratios.In addition, iDC maturation responses to CD40L and lipopolysaccharide were significantly inhibited.We conclude that opsonization of apoptotic cells by iC3b induces tolerant iDCs that are able to migrate to lymph nodes.

View Article: PubMed Central - PubMed

Affiliation: The Laboratory for Cellular and Molecular Immunology, Rheumatology Unit, Department of Medicine, Hadassah Hospital and the Hebrew University. Sourasky Medical Center, Jerusalem 91120, Israel.

ABSTRACT
Immature dendritic cells (iDCs) do not mature after uptake of apoptotic cells and may play a role in the induction of peripheral tolerance to self antigens derived from apoptotic material. The integrins, alphavbeta3, alphavbeta5, and the scavenger receptor, CD36, have been shown to mediate uptake of apoptotic cells by iDCs. However, it is not known whether the complement system, also takes part in this process. In this study we investigated the ability of iDCs to bind to apoptotic cells opsonized by iC3b. Monocyte-derived dendritic cells were offered apoptotic Jurkat cells opsonized by autologous iC3b and labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethyl-indocarbocyanineperchlorate. A significant increase (P < 0.001) in the amount of cleared apoptotic cells was seen at low ratios. Despite increased efficiency of uptake, interaction between iC3b-opsonized apoptotic cells and iDCs down-regulated the expression of major histocompatibility complex class II, CD86, CC chemokine receptor (CCR)2, CCR5, and beta2-integrins (P < 0.001), and up-regulated expression of CCR7 (P < 0.001). In addition, iDC maturation responses to CD40L and lipopolysaccharide were significantly inhibited. We conclude that opsonization of apoptotic cells by iC3b induces tolerant iDCs that are able to migrate to lymph nodes.

Show MeSH
Related in: MedlinePlus