| 1. |
- Asplund, Annika, 1979, et al.
(författare)
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Hypoxia increases macrophage motility, possibly by decreasing the heparan sulfate proteoglycan biosynthesis.
- 2009
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Ingår i: Journal of leukocyte biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 86:2, s. 381-8
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Tidskriftsartikel (refereegranskat)abstract
- Macrophages are recruited and retained in hypoxic sites in atherosclerotic lesions and tumors. Furthermore, macrophages are suggested to be a major source of HSPG synthesis in atherosclerotic lesions. HSPG are, among other things, known to regulate cell motility, cell adhesion, and receptor interaction. The aim of this study was to investigate the effect of hypoxia on HSPG expression and macrophage motility. We also explored the potential regulation of HSPG by the transcription factor HIF-1alpha. The nondirected cell motility was increased in HMDM after 24 h exposure to hypoxia (0.5% O(2)) compared with normal cell culture condition (21% O(2)). Enzymatic degradation of HS GAG further increased the motility of the HMDM in hypoxia, indicating a role of reduced cell-associated HSPG in the increased HMDM motility. HMDM exposed to 24 h of hypoxia had lower mRNA expressions of syndecan-1 and -4 compared with cells exposed to normal cell culture conditions. Protein levels of syndecan-1 were also decreased significantly in response to hypoxia, and cells subjected to hypoxia had lower mRNA expression for key enzymes involved in HS biosynthesis. In addition, hypoxia was found to reduce the relative content of HS GAG. Transfecting THP-1 cells with siHIF-1alpha indicated that this transcription factor was not involved in the hypoxia-induced modifications of HSPG expression. Given the documented multiple functions of HSPG in macrophage behavior, the hypoxia-induced modifications of HSPG may be of relevance for the development of atherosclerotic lesions and tumor progression.
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| 2. |
- Asplund, Annika, 1979, et al.
(författare)
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Hypoxic regulation of secreted proteoglycans in macrophages.
- 2010
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 1460-2423 .- 0959-6658. ; 20:1, s. 33-40
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Tidskriftsartikel (refereegranskat)abstract
- Macrophages are prominent in hypoxic areas of atherosclerotic lesions, and their secreted proteoglycans (PG), such as versican, can modulate the retention of lipoproteins and the activity of enzymes, cytokines, and growth factors involved in atherogenesis. In this study, we report the effects of hypoxia on PG secreted by human monocyte-derived macrophages (HMDM) and the potential regulation by the transcription factor hypoxia-inducible factor (HIF-1alpha and HIF-2alpha). We found that versican co-localized with HIF-1alpha in macrophage-rich areas in human advanced atherosclerotic lesions. Versican and perlecan mRNA expression increased after exposure to 0.5% O(2) (hypoxia) compared with 21% O(2) (control cells). Using precursors to GAG biosynthesis combined with immunoabsorption with a versican antibody an increased versican synthesis was detected at hypoxia. Furthermore, siRNA knockdown of HIF-1alpha and HIF-2alpha in THP-1 cells showed that the hypoxic induction of versican and perlecan mRNA expression involved HIF signaling. Versican expression was co-regulated by HIF-1alpha and HIF-2alpha but expression of perlecan was influenced only by HIF-1alpha and not by HIF-2alpha knockdown. The results show that oxygen concentration is an important modulator of PG expression in macrophages. This may be a novel component of the complex role of macrophages in atherosclerosis.
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| 3. |
- Asplund, Annika, 1979, et al.
(författare)
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Macrophages exposed to hypoxia secrete proteoglycans for which LDL has higher affinity
- 2011
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Ingår i: ATHEROSCLEROSIS. - 0021-9150. ; 215:1, s. 77-81
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Tidskriftsartikel (refereegranskat)abstract
- Macrophages are prominent in hypoxic areas of atherosclerotic lesions. Their secreted proteoglycans (PG) can modulate the retention of lipoproteins as well as the activity of enzymes, cytokines, and growth factors involved in atherogenesis. Versican appears to be one of the main extracellular matrix components binding LDL in the arterial intima. We have recently shown that hypoxia increases versican and perlecan expression in macrophages, and that this increase was regulated by the hypoxia inducible factor (HIF). Here we report effects of hypoxia on human monocyte-derived macrophage (HMDM) secreted glycosaminoglycans (GAG), and its interaction with LDL. After 24 h exposure to 0.5% O2 (hypoxia), metabolically labeled GAG of secreted PG had higher affinity for LDL compared to 21% O2 (control cells). GAG secreted by HMDM in hypoxia were found to be more sulfated and longer which might be responsible for the increased affinity of LDL for these GAG chains. These results indicate that hypoxia induced changes in macrophage GAG biosynthesis have important consequences for the interaction with LDL. If present in vivo, an augmented association of GAG with LDL might contribute to the development of atherosclerosis in hypoxic intima.
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| 4. |
- Asplund, Annika, 1979-, et al.
(författare)
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One Standardized Differentiation Procedure Robustly Generates Homogenous Hepatocyte Cultures Displaying Metabolic Diversity from a Large Panel of Human Pluripotent Stem Cells
- 2016
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Ingår i: Stem Cell Reviews and Reports. - : Springer Science and Business Media LLC. - 1550-8943 .- 1558-6804. ; 12:1, s. 90-104
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Tidskriftsartikel (refereegranskat)abstract
- Human hepatocytes display substantial functional inter-individual variation regarding drug metabolizing functions. In order to investigate if this diversity is mirrored in hepatocytes derived from different human pluripotent stem cell (hPSC) lines, we evaluated 25 hPSC lines originating from 24 different donors for hepatic differentiation and functionality. Homogenous hepatocyte cultures could be derived from all hPSC lines using one standardized differentiation procedure. To the best of our knowledge this is the first report of a standardized hepatic differentiation procedure that is generally applicable across a large panel of hPSC lines without any adaptations to individual lines. Importantly, with regard to functional aspects, such as Cytochrome P450 activities, we observed that hepatocytes derived from different hPSC lines displayed inter-individual variation characteristic for primary hepatocytes obtained from different donors, while these activities were highly reproducible between repeated experiments using the same line. Taken together, these data demonstrate the emerging possibility to compile panels of hPSC-derived hepatocytes of particular phenotypes/genotypes relevant for drug metabolism and toxicity studies. Moreover, these findings are of significance for applications within the regenerative medicine field, since our stringent differentiation procedure allows the derivation of homogenous hepatocyte cultures from multiple donors which is a prerequisite for the realization of future personalized stem cell based therapies.
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| 5. |
- Asplund, Annika, 1979
(författare)
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The effect of hypoxia on macrophage proteoglycans: potential role in atherosclerosis
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A critical step in the development of atherosclerotic lesions appears to be the retention of low density lipoproteins (LDL) in the arterial wall, mediated by negatively charged proteoglycans (PG). Retained LDL is susceptible to modification and uptake by resident macrophages that are found in hypoxic sites in atherosclerotic lesions (with oxygen levels below 1%). PG are multifunctional proteins and in addition to their interaction with LDL, they bind and regulate the activity of growth factors and cytokines as well as cell migration and adhesion. The aim of this thesis was to investigate how hypoxia affects PG synthesis in macrophages and the potential consequences on the atherosclerotic process. We found that expression of two large secreted PG, versican and perlecan, was increased in human monocyte-derived macrophages (HMDM) exposed to hypoxia (0.5% O2) compared with cells in normal cell culture conditions (21% O2). We found that the hypoxic induction of these two PG involved the hypoxia-inducible transcription factors HIF-1α and HIF-2α, and that HIF-1α and versican co-localized in macrophage-rich areas in human advanced atherosclerotic lesions. The negative charge of PG is on their attached glycosaminoglycans (GAG). We found that GAG secreted under hypoxic conditions bound LDL with higher affinity than GAG secreted under normal cell culture conditions, which could be due to the increased sulfation and size of GAG secreted in hypoxia. In contrast to the hypoxic induction of macrophage-secreted PG, hypoxia decreased the synthesis of the cell-associated heparan sulfate (HS) PG syndecan-1 as well as the HS GAG chains. The general motility of macrophages increased upon hypoxic incubation and was associated with the amount of HS GAG chains. In conclusion, we found that hypoxia affects the synthesis of the extracellular matrix PG in macrophages with the potential to contribute to increased LDL deposition. Hypoxia also modulates the synthesis of cell-associated PG, with consequences for HMDM cell motility. These results are of importance to understand the role of macrophages in biological processes such as atherosclerosis.
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| 6. |
- Ghosheh, Nidal, et al.
(författare)
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Highly Synchronized Expression of Lineage-Specific Genes during In Vitro Hepatic Differentiation of Human Pluripotent Stem Cell Lines
- 2016
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Ingår i: Stem Cells International. - : Hindawi Limited. - 1687-966X .- 1687-9678.
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Tidskriftsartikel (refereegranskat)abstract
- Human pluripotent stem cells- (hPSCs-) derived hepatocytes have the potential to replace many hepatic models in drug discovery and provide a cell source for regenerative medicine applications. However, the generation of fully functional hPSC-derived hepatocytes is still a challenge. Towards gaining better understanding of the differentiation and maturation process, we employed a standardized protocol to differentiate six hPSC lines into hepatocytes and investigated the synchronicity of the hPSC lines by applying RT-qPCR to assess the expression of lineage-specific genes (OCT4, NANOG, T, SOX17, CXCR4, CER1, HHEX, TBX3, PROX1, HNF6, AFP, HNF4a, KRT18, ALB, AAT, and CYP3A4) which serve as markers for different stages during liver development. The data was evaluated using correlation and clustering analysis, demonstrating that the expression of these markers is highly synchronized and correlated well across all cell lines. The analysis also revealed a distribution of the markers in groups reflecting the developmental stages of hepatocytes. Functional analysis of the differentiated cells further confirmed their hepatic phenotype. Taken together, these results demonstrate, on the molecular level, the highly synchronized differentiation pattern across multiple hPSC lines. Moreover, this study provides additional understanding for future efforts to improve the functionality of hPSC-derived hepatocytes and thereby increase the value of related models.
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| 7. |
- Ghosheh, Nidal, 1975-, et al.
(författare)
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Human Pluripotent Stem Cell-Derived Hepatocytes Show Higher Transcriptional Correlation with Adult Liver Tissue than with Fetal Liver Tissue
- 2020
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 5:10, s. 4816-4827
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Tidskriftsartikel (refereegranskat)abstract
- Human pluripotent stem cell-derived hepatocytes (hPSC-HEP) display many properties of mature hepatocytes, including expression of important genes of the drug metabolizing machinery, glycogen storage, and production of multiple serum proteins. To this date, hPSC-HEP do not, however, fully recapitulate the complete functionality of in vivo mature hepatocytes. In this study, we applied versatile bioinformatic algorithms, including functional annotation and pathway enrichment analyses, transcription factor binding-site enrichment, and similarity and correlation analyses, to datasets collected from different stages during hPSC-HEP differentiation and compared these to developmental stages and tissues from fetal and adult human liver. Our results demonstrate a high level of similarity between the in vitro differentiation of hPSC-HEP and in vivo hepatogenesis. Importantly, the transcriptional correlation of hPSC-HEP with adult liver (AL) tissues was higher than with fetal liver (FL) tissues (0.83 and 0.70, respectively). Functional data revealed mature features of hPSC-HEP including cytochrome P450 enzymes activities and albumin secretion. Moreover, hPSC-HEP showed expression of many genes involved in drug absorption, distribution, metabolism, and excretion. Despite the high similarities observed, we identified differences of specific pathways and regulatory players by analyzing the gene expression between hPSC-HEP and AL. These findings will aid future intervention and improvement of in vitro hepatocyte differentiation protocol in order to generate hepatocytes displaying the complete functionality of mature hepatocytes. Finally, on the transcriptional level, our results show stronger correlation and higher similarity of hPSC-HEP to AL than to FL. In addition, potential targets for further functional improvement of hPSC-HEP were also identified.
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| 8. |
- Sayin, Volkan I., 1983, et al.
(författare)
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Loss of One Copy of Zfp148 Reduces Lesional Macrophage Proliferation and Atherosclerosis in Mice by Activating p53
- 2014
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Ingår i: Circulation Research. - : Ovid Technologies (Wolters Kluwer Health). - 0009-7330 .- 1524-4571. ; 115:9, s. 781-791
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Tidskriftsartikel (refereegranskat)abstract
- Rationale: Cell proliferation and cell cycle control mechanisms are thought to play central roles in the pathogenesis of atherosclerosis. The transcription factor Zinc finger protein 148 (Zfp148) was shown recently to maintain cell proliferation under oxidative conditions by suppressing p53, a checkpoint protein that arrests proliferation in response to various stressors. It is established that inactivation of p53 accelerates atherosclerosis, but whether increased p53 activation confers protection against the disease remains to be determined. Objective: We aimed to test the hypothesis that Zfp148 deficiency reduces atherosclerosis by unleashing p53 activity. Methods and Results: Mice harboring a gene-trap mutation in the Zfp148 locus (Zfp148(gt/+)) were bred onto the apolipoprotein E (Apoe)(-/-) genetic background and fed a high-fat or chow diet. Loss of 1 copy of Zfp148 markedly reduced atherosclerosis without affecting lipid metabolism. Bone marrow transplantation experiments revealed that the effector cell is of hematopoietic origin. Peritoneal macrophages and atherosclerotic lesions from Zfp148(gt/+)Apoe(-/-) mice showed increased levels of phosphorylated p53 compared with controls, and atherosclerotic lesions contained fewer proliferating macrophages. Zfp148(gt/+) Apoe(-/-) mice were further crossed with p53-null mice (Trp53(-/-) [the gene encoding p53]). There was no difference in atherosclerosis between Zfp148(gt/+) Apoe(-/-) mice and controls on a Trp53(+/-) genetic background, and there was no difference in levels of phosphorylated p53 or cell proliferation. Conclusions: Zfp148 deficiency increases p53 activity and protects against atherosclerosis by causing proliferation arrest of lesional macrophages, suggesting that drugs targeting macrophage proliferation may be useful in the treatment of atherosclerosis.
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