Proinflammatory stimuli enhance phagocytosis of apoptotic cells by neutrophil granulocytes.
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ABSTRACT:
SUBMITTER: Hellberg L
PROVIDER: S-EPMC3217599 | biostudies-other | 2011
REPOSITORIES: biostudies-other
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Project description:Natural Abs, which arise without known immune exposure, have been described that specifically recognize cells dying from apoptosis, but their role in innate immunity remains poorly understood. Herein, we show that the immune response to neoantigenic determinants on apoptotic thymocytes is dominated by Abs to oxidation-associated Ags, phosphorylcholine (PC), a head group that becomes exposed during programmed cell death, and malondialdehyde (MDA), a reactive aldehyde degradation product of polyunsaturated lipids produced following exposure to reactive oxidation species. While natural Abs to apoptotic cells in naive adult mice were dominated by PC and MDA specificities, the amounts of these Abs were substantially boosted by treatment of mice with apoptotic cells. Moreover, the relative amounts of PC and MDA Abs was affected by V(H) gene inheritance. Ab interactions with apoptotic cells also mediated the recruitment of C1q, which enhanced apoptotic cell phagocytosis by immature dendritic cells. Significantly, IgM Abs to both PC and MDA were primary factors in determining the efficiency of serum-dependent apoptotic cell phagocytosis. Hence, we demonstrate a mechanism by which certain natural Abs that recognize neoantigens on apoptotic cells, in naive mice and those induced by immune exposure to apoptotic cells, can enhance the functional capabilities of immature dendritic cells for phagocytic engulfment of apoptotic cells.
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Project description:Natural antibodies, which arise without known immune exposure, have been described that specifically recognize cells dying from apoptosis but their role in innate immunity remains poorly understood. Herein, we show that the immune response to neo-antigenic determinants on apoptotic thymocytes is dominated by antibodies to oxidation-associated antigens, phosphorylcholine (PC), a head group that becomes exposed during programmed-cell death, and malondialdehyde (MDA), a reactive aldehyde degradation product of polyunsaturated lipids produced following exposure to reactive-oxidation species. While natural antibodies to apoptotic cells in naM-CM-/ve adult mice were dominated by PC and MDA specificities, the amounts of these antibodies were substantially boosted by treatment of mice with apoptotic cells. Moreover, the relative amounts of PC and MDA antibodies was affected by VH gene inheritance. Antibody interactions with apoptotic-cells also mediated the recruitment of C1q, which alone can promote apoptotic-cell phagocytosis by immature dendritic cells. Significantly, IgM-antibodies to both PC and MDA were primary factors in determining the efficiency of serum-dependent apoptotic-cell phagocytosis. Hence, we demonstrate a mechanism by which certain natural antibodies that recognize neo-antigens on apoptotic cells, in naM-CM-/ve mice and those induced by immune exposure to apoptotic-cells, can enhance the functional capabilities of immature dendritic cells for phagocytic engulfment of apoptotic cells. Keywords: Natural antibodies, Inflammation, Complement, Apoptosis In the study presented here, a total of 11 custom-spotted protein slides were hybridized with a T15 IgM monoclonal antibody at three different concentrations, an isotype control IgM, 2 slides were hybridized with serum from naM-QM-^Wve mice, 2 slides incubated with serum from mice immunized with apoptotic cells, 2 slides were incubated with serum from mice immunized with saline, and a negative control slide with no antibody hybridized
2009-02-23 | E-GEOD-14958 | biostudies-arrayexpress
Project description:Apoptosis is a noninflammatory, programmed form of cell death. One mechanism underlying the non-phlogistic nature of the apoptosis program is the swift phagocytosis of the dying cells. How apoptotic cells attract mononuclear phagocytes and not granulocytes, the professional phagocytes that accumulate at sites of inflammation, has not been determined. Here, we show that apoptotic human cell lines of diverse lineages synthesize and secrete lactoferrin, a pleiotropic glycoprotein with known antiinflammatory properties. We further demonstrated that lactoferrin selectively inhibited migration of granulocytes but not mononuclear phagocytes, both in vitro and in vivo. Finally, we were able to attribute this antiinflammatory function of lactoferrin to its effects on granulocyte signaling pathways that regulate cell adhesion and motility. Together, our results identify lactoferrin as an antiinflammatory component of the apoptosis milieu and define what we believe to be a novel antiinflammatory property of lactoferrin: the ability to function as a negative regulator of granulocyte migration.
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Project description:Natural antibodies, which arise without known immune exposure, have been described that specifically recognize cells dying from apoptosis but their role in innate immunity remains poorly understood. Herein, we show that the immune response to neo-antigenic determinants on apoptotic thymocytes is dominated by antibodies to oxidation-associated antigens, phosphorylcholine (PC), a head group that becomes exposed during programmed-cell death, and malondialdehyde (MDA), a reactive aldehyde degradation product of polyunsaturated lipids produced following exposure to reactive-oxidation species. While natural antibodies to apoptotic cells in naïve adult mice were dominated by PC and MDA specificities, the amounts of these antibodies were substantially boosted by treatment of mice with apoptotic cells. Moreover, the relative amounts of PC and MDA antibodies was affected by VH gene inheritance. Antibody interactions with apoptotic-cells also mediated the recruitment of C1q, which alone can promote apoptotic-cell phagocytosis by immature dendritic cells. Significantly, IgM-antibodies to both PC and MDA were primary factors in determining the efficiency of serum-dependent apoptotic-cell phagocytosis. Hence, we demonstrate a mechanism by which certain natural antibodies that recognize neo-antigens on apoptotic cells, in naïve mice and those induced by immune exposure to apoptotic-cells, can enhance the functional capabilities of immature dendritic cells for phagocytic engulfment of apoptotic cells. Keywords: Natural antibodies, Inflammation, Complement, Apoptosis
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