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| 2. |
- Edin, Sofia, et al.
(author)
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The Distribution of Macrophages with a M1 or M2 Phenotype in Relation to Prognosis and the Molecular Characteristics of Colorectal Cancer
- 2012
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In: PLOS ONE. - : PLoS One. - 1932-6203. ; 7:10, s. e47045-
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Journal article (peer-reviewed)abstract
- High macrophage infiltration has been correlated to improved survival in colorectal cancer (CRC). Tumor associated macrophages (TAMs) play complex roles in tumorigenesis since they are believed to hold both tumor preventing (M1 macrophages) and tumor promoting (M2 macrophages) activities. Here we have applied an immunohistochemical approach to determine the degree of infiltrating macrophages with a M1 or M2 phenotype in clinical specimens of CRC in relation to prognosis, both in CRC in general but also in subgroups of CRC defined by microsatellite instability (MSI) screening status and the CpG island methylator phenotype (CIMP). A total of 485 consecutive CRC specimens were stained for nitric oxide synthase 2 (NOS2) (also denoted iNOS) as a marker for the M1 macrophage phenotype and the scavenger receptor CD163 as a marker for the M2 macrophage phenotype. The average infiltration of NOS2 and CD163 expressing macrophages along the invasive tumor front was semi-quantitatively evaluated using a four-graded scale. Two subtypes of macrophages, displaying M1 (NOS2(+)) or M2 (CD163(+)) phenotypes, were recognized. We observed a significant correlation between the amount of NOS2(+) and CD163(+) cells (P<0.0001). A strong inverse correlation to tumor stage was found for both NOS2 (P<0.0001) and CD163 (P<0.0001) infiltration. Furthermore, patients harbouring tumors highly infiltrated by NOS2+ cells had a significantly better prognosis than those infiltrated by few NOS2+ cells, and this was found to be independent of MSI screening status and CIMP status. No significant difference was found on cancer-specific survival in groups of CRC with different NOS2/CD163 ratios. In conclusion, an increased infiltration of macrophages with a M1 phenotype at the tumor front is accompanied by a concomitant increase in macrophages with a M2 phenotype, and in a stage dependent manner correlated to a better prognosis in patients with CRC.
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| 3. |
- Gardai, Shyra J, et al.
(author)
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Cell-surface calreticulin initiates clearance of viable or apoptotic cells through trans-activation of LRP on the phagocyte
- 2005
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In: Cell. - : Elsevier BV. - 0092-8674 .- 1097-4172. ; 123:2, s. 321-334
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Journal article (peer-reviewed)abstract
- Apoptotic-cell removal is critical for development, tissue homeostasis, and resolution of inflammation. Although many candidate systems exist, only phosphatidylserine has been identified as a general recognition ligand on apoptotic cells. We demonstrate here that calreticulin acts as a second general recognition ligand by binding and activating LDL-receptor-related protein (LRP) on the engulfing cell. Since surface calreticulin is also found on viable cells, a mechanism preventing inadvertent uptake was sought. Disruption of interactions between CD47 (integrin-associated protein) on the target cell and SIRPalpha (SHPS-1), a heavily glycosylated transmembrane protein on the engulfing cell, permitted uptake of viable cells in a calreticulin/LRP-dependent manner. On apoptotic cells, CD47 was altered and/or lost and no longer activated SIRPalpha. These changes on the apoptotic cell create an environment where "don't eat me" signals are rendered inactive and "eat me" signals, including calreticulin and phosphatidylserine, congregate together and signal for removal.
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| 4. |
- Henriksson, Maria L, et al.
(author)
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Colorectal Cancer Cells Activate Adjacent Fibroblasts Resulting in FGF1/FGFR3 Signaling and Increased Invasion.
- 2011
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In: American Journal of Pathology. - : Elsevier. - 0002-9440 .- 1525-2191. ; 178:3, s. 1387-1394
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Journal article (peer-reviewed)abstract
- Cancer-associated fibroblasts expressing fibroblast activation protein (FAP) have been implicated in the invasive behavior of colorectal cancer. In this study, we use FAP expression as a marker of fibroblast activation and analyze the effect of activated fibroblasts on colorectal cancer migration and invasion in experimental cell studies. We also investigated the expression pattern of FAP in cancer-associated fibroblasts during transformation from benign to malignant colorectal tumors. In immunohistochemical analyses, FAP was expressed in fibroblasts in all colorectal cancer samples examined, whereas all normal colon, hyperplastic polyps, or adenoma samples were negative. In in vitro studies, conditioned medium from colon cancer cells, but not adenoma cells, activated fibroblasts by inducing FAP expression. These activated fibroblasts increased the migration and invasion of colon cancer cells in Boyden chamber experiments and in a three-dimensional cell culture model. We identify fibroblast growth factor 1/fibroblast growth factor receptor 3 (FGF1/FGFR-3) signaling as mediators leading to the increased migration and invasion. Activated fibroblasts increase their expression of FGF1, and by adding a fibroblast growth factor receptor inhibitor, as well as an FGF1-neutralizing antibody, we reduced the migration of colon cancer cells. Our findings provide evidence of a possible molecular mechanism involved in the cross talk between cancer cells and fibroblasts leading to cancer cell invasion.
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| 5. |
- Larsson, Anders, et al.
(author)
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Red blood cells with elevated cytoplasmic Ca2+ are primarily taken up by splenic marginal zone macrophages and CD207+dendritic cells
- 2016
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In: Transfusion. - : Wiley. - 0041-1132 .- 1537-2995. ; 56:7, s. 1834-1844
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Journal article (peer-reviewed)abstract
- BACKGROUND: The normal red blood cell (RBC) life span may be significantly reduced when RBCs are stored under blood bank conditions, resulting in a reduced 24-hour survival after transfusion. The damage of stored RBCs is probably multifactorial as stored RBCs share features of both senescence and suicidal RBC death (eryptosis). Since an increased intracellular Ca2+ concentration ([Ca2+](i)) is one key feature of eryptosis, we here investigated if stored human RBCs had increased [Ca2+](i) and the mechanisms behind uptake of such RBCs in a murine model.STUDY DESIGN AND METHODS: The intracellular Ca2+ content of RBCs was determined using the Ca2+ probe Fluo-3 and flow cytometry. In vivo uptake of Ca2+ ionophore-treated murine RBCs (Ca2+-RBCs) was investigated in recipient mice, using flow cytometry and immunohistochemical analysis.RESULTS: A small fraction of human RBCs accumulated [Ca2+](i) during storage for up to 42 days under blood bank conditions. In a murine model, where fresh or Ca2+-RBCs were transfused, Ca2+-RBCs were mainly trapped by MARCO+ splenic marginal zone macrophages and CD11c+ CD207+ dendritic cells (DCs) within 1 hour after transfusion. In marked contrast, freshly transfused RBCs aging normally in circulation were cleared much slower and preferentially by F4/80+ red pulp macrophages. CD47 on the Ca2+-RBCs did not affect their clearance by splenic phagocytic cells.CONCLUSIONS: A small fraction of RBCs accumulate [Ca2+](i) during storage, and in a murine model such RBCs are recognized by splenic macrophages and DCs in ways similar to what has been reported for nucleated apoptotic cells.
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| 6. |
- Larsson, Anders, et al.
(author)
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Splenic uptake of RBCs with an elevated cytoplasmic Ca2+-concentration primarily involves marginal zone macrophages and CD207+ dendritic cells
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Other publication (other academic/artistic)abstract
- Normally senescent red blood cells (RBCs) have a rather fixed life-span after which they are eliminated from the circulation mainly by macrophages in the spleen and liver. However, the normal life-span may be significantly reduced when RBCs are stored under blood bank conditions, which ultimately results in a reduced 24 hour survival after transfusion. Although not completely understood, the damage occurring to some of the stored RBCs is probably multifactorial as stored RBCs shares features of both senescence and suicidal RBC death (eryptosis). One key cellular event associated with eryptosis is an increased intracellular Ca2+-concentration. We found that human RBCs stored for up to 42 days under blood bank conditions contained a small subset of cells with an increased intracellular Ca2+-concentration corresponding to that during eryptosis. Since little is known about the mechanisms mediating uptake and clearance of eryptotic RBCs in vivo, we further investigated this using a murine transfusion model of Ca2+ ionophore-treated RBCs (Ca2+-RBCs). Ca2+-RBCs were mainly trapped by MARCO+ splenic marginal zone macrophages and CD11c+ dendritic cells (DCs) already at 1 hour after transfusion. Among DCs, CD11c+ CD207+ DCs in the marginal zone were particularly efficient in mediating uptake of Ca2+-RBCs. Similar to that found in vitro, CD47 on the Ca2+-RBCs did not affect their clearance in vivo. Thus, RBCs with an increased intracellular Ca2+-concentration accumulates during RBC storage, and in a murine model such RBCs are recognized by splenic macrophages and DCs in ways similar to what has been reported for nucleated apoptotic cells.
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| 7. |
- Nilsson, Anna, 1978-, et al.
(author)
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CD47 promotes both phosphatidylserine-independent and phosphatidylserine-dependent phagocytosis of apoptotic murine thymocytes by non-activated macrophages
- 2009
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In: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier. - 0006-291X .- 1090-2104. ; 387:1, s. 58-63
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Journal article (peer-reviewed)abstract
- The ubiquitously expressed cell surface glycoprotein CD47 on host cells can inhibit phagocytosis of unopsonized or opsonized viable host target cells. Here we studied the role of target cell CD47 in macrophage uptake of viable or apoptotic murine thymocytes. As expected, IgG-opsonized viable CD47-/- thymocytes were taken up more efficiently than equally opsonized Wt thymocytes. However IgG-opsonized apoptotic thymocytes from Wt and CD47-/- mice were taken up equally. Although uptake of apoptotic thymocytes by non-activated bone marrow-derived macrophages was phosphatidylserine (PS)-independent, while uptake by non-activated resident peritoneal macrophages was PS-dependent, both macrophage populations showed a reduced uptake of non-opsonized apoptotic CD47-/- thymocytes, as compared with the uptake of apoptotic Wt thymocytes. This difference was only seen with non-activated macrophages, and not with β-1,3-glucan-activated macrophages. CD47 promoted binding of thymocytes to macrophages, which did not require F-actin polymerization. CD47 became clustered on apoptotic thymocytes, both colocalized with or separated from, clustered PS and cholesterol-rich GM-1 domains. Thus, CD47 does not inhibit, but rather support, both PS-independent and PS-dependent uptake of apoptotic cells in the murine system. This mechanism only comes into play in non-activated macrophages.
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| 8. |
- Nilsson, Anna, et al.
(author)
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Macrophage expression of LRP1, a receptor for apoptotic cells and unopsonized erythrocytes, can be regulated by glucocorticoids
- 2012
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In: Biochemical and Biophysical Research Communications - BBRC. - San Diego : Elsevier. - 0006-291X .- 1090-2104. ; 417:4, s. 1304-1309
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Journal article (peer-reviewed)abstract
- Macrophage phagocytosis of apoptotic cells, or unopsonized viable CD47(-/-) red blood cells, can be mediated by the interaction between calreticulin (CRT) on the target cell and LDL receptor-related protein-1 (LRP1/CD91/alpha 2-macroglobulin receptor) on the macrophage. Glucocorticoids (GC) are powerful in treatment of a range of inflammatory conditions, and were shown to enhance macrophage uptake of apoptotic cells. Here we investigated if the ability of GC to promote macrophage uptake of apoptotic cells could in part be mediated by an upregulation of macrophage LRP1 expression. Using both resident peritoneal and bone marrow-derived macrophages, we found that the GC dexamethasone could dose- and time-dependently increase macrophage LRP1 expression. The GC receptor-inhibitor RU486 could dose-dependently prevent LRP1 upregulation. Dexamethasone-treated macrophages did also show enhanced phagocytosis of apoptotic thymocytes as well as unopsonized viable CD47(-/-) red blood cells, which was sensitive to inhibition by the LRP1-agonist RAP. In conclusion, these data suggest that GC-stimulated macrophage uptake of apoptotic cells may involve an upregulation of macrophage LRP1 expression and enhanced LRP1-mediated phagocytosis. (C) 2012 Elsevier Inc. All rights reserved.
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| 9. |
- Nilsson, Anna, 1978-
(author)
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Mechanisms involved in macrophage phagocytosis of apoptotic cells
- 2009
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Doctoral thesis (other academic/artistic)abstract
- Efficient removal of apoptotic cells is critical for development, tissue remodelling, maintenance of homeostasis, and response to injury. Phagocytosis of apoptotic cells is mediated by many phagocytic receptors, soluble bridging molecules, and pro-phagocytic ligands on the surface of apoptotic cells. Macrophage phagocytosis in general is controlled by stimulatory and inhibitory mechanisms. An example of the latter mechanism is that mediated by the cell surface glycoprotein CD47, which by binding to the inhibitory receptor Signal Regulatory Protein alpha (SIRPα) on macrophages, is known to inhibit phagocytosis of viable host cells. The studies of the present thesis aimed at investigating possible changes to CD47 on apoptotic cells, which could influence their elimination by macrophages. The endoplasmatic protein calreticulin (CRT), in conjunction with Low density lipoprotein Receptorrelated Protein 1 (LRP1) on the phagocyte, can act as a receptor for collectin family members and mediate uptake of apoptotic cells. However, CRT itself was found to also be expressed on the surface of many viable cell types, and the CRT expression increased on apoptotic cells. By using antibodies to LRP1 or receptor‐associated protein (RAP), an antagonist blocking LRP1 ligand binding, we found that CRT on target cells could interact in trans with LRP1 on a phagocyte and stimulate phagocytosis. CD47 on the target cell inhibited LRP1‐mediated phagocytosis of viable cells (e.g. lymphocytes or erythtocytes), but not that of apoptotic cells. The inability of CD47 on apoptotic cells to inhibit LRP1‐ mediated phagocytosis could be explained in two ways: 1) Some apoptotic cell types (fibroblasts and neutrophils, but not Jurkat T cells) lost CD47 from the cell surface, or 2) CD47 is evenly distributed on the surface of viable cells, while it was redistributed into patches on apoptotic cells, segregated away from areas of the plasma membrane where the pro‐phagocytic ligands CRT and phoaphatidylserine (PS) were concentrated. Apoptotic murine thymocytes also showed a patched distribution of CD47, but no significant loss of the receptor. However, both PS‐independent and PS‐dependent macrophage phagocytosis of apoptotic CD47‐/‐ thymocytes was less efficient than uptake of apoptotic wild‐type (wt) thymocytes. This contradictory finding was explained by the fact that CD47 on apoptotic thymocytes did no longer inhibit phagocytosis, but rather mediated binding of the apoptotic cell to the macrophage. These effects could in part be dependent on the apoptotic cell type, since uptake of experimentally senescent PS+ wt or CD47‐/‐ erythrocytes by macrophage in vitro, or by dendritic cells (DC) in vivo, were the same. In vivo, PS+ erythrocytes were predominantly trapped by marginal zone macrophages and by CD8+ CD207+ DCs in the splenic marginal zone. DCs which had taken up PS+ erythrocytes showed a slight increase in expression levels of CD40, CD86 and MHC class II. These findings suggest that PS+ erythrocytes may be recognized by splenic macrophages and DCs in ways similar to that reported for apoptotic T cells. Uptake of senescent erythrocytes by DCs may serve as an important mechanism to maintain self‐tolerance to erythrocyte antigens, and defects in this function may facilitate development of AIHA. Glucocorticoids are used to treat inflammatory conditions and can enhance macrophage uptake of apoptotic cells. We found that the glucocorticoid dexamethasone time‐ and dose‐dependently stimulated macrophage cell surface LRP1 expression. Dexamethasone‐stimulated macrophages also showed enhanced phagocytosis of apoptotic thymocytes and unopsonized viable CD47‐/‐ erythrocytes. In summary, LRP1 can mediate phagocytosis of both viable and apoptotic cells by binding CRT on the target cell. Macrophage expression of LRP1 is increased by glucocorticoids, which could be one explanation for the anti‐inflammatory role of glucocorticoids. While CD47 on viable cells efficiently inhibits phagocytosis in macrophages, CD47 on apoptotic cells does not and can sometimes even promote their removal.
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| 10. |
- Nilsson, Anna, 1978-, et al.
(author)
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Role of CD47 in regulating macrophage and dendritic cell uptake of calcium-induced experimentally senescent erythrocytes in vitro and in vivo
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Other publication (other academic/artistic)abstract
- During senescence, erythrocytes are rapidly eliminated by phagocytes in the spleen and liver,and the interplay between macrophages or dendritic cells (DCs) with lymphocytes in the spleen could be of importance to regulate self-tolerance and to prevent development of autoimmune hemolytic anemia (AIHA).The cell surface glycoprotein CD47 on the surface of host target cells can inhibit phagocytosis of normal circulating blood cells by binding to signal regulatory protein alpha (SIRPα) on macrophages and DCs. Here we investigated the clearance of Ca2+-ionophore-treated experimentally senescent erythrocytes (Ca2+-RBCs) in vivo, and if CD47 on Ca2+-RBCs regulated their uptake by macrophages in vitro or their clearance in vivo. Ca2+-RBCs exposed phosphatidylserine (PS) on their surface and were rapidly phagocytosed by macrophages in vitro. This uptake was dependent on heat-stable serum factors, but was not inhibited by CD47 on the erythrocytes. Following intravenous injection, a large fraction of PKH26-labeled Ca2+-RBCs were trapped by splenic marginal zone macrophages and DCs within 1 hour. In addition, at 20 hours after injection fluorescence from the injected cells could also be detected within the T cell area of the splenic white pulp and associated with both CD8+ and CD8- DCs. We found that DCs in wild-type (Wt) recipient mice showed equal uptake of transfused Wt and CD47-/- Ca2+-RBCs. DCs which had taken up Ca2+-RBCs showed a slight increase in expression levels of CD40, CD86 and MHC class II. In recipients of CD47-/- Ca2+-RBCs, DCs negative for RBC-uptake showed strongly increased expression of CD86, as compared with that in recipients of Wt Ca2+-RBCs. These findings suggest that PS+ erythrocytes may be recognized by splenic macrophages and DCs in ways similar to that reported for nucleated apoptotic cells. Uptake of senescent erythrocytes by DCs may serve as an important mechanism to maintain self-tolerance to erythrocyte antigens, and defects in this function may facilitate development of AIHA.
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