Browsing by Subject "Macrophages"

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  • Arnal-Levron, Maud; Chen, Yinan; Greimel, Peter; Calevro, Federica; Gaget, Karen; Riols, Fabien; Batut, Aurélie; Bertrand-Michel, Justine; Hullin-Matsuda, Françoise; Olkkonen, Vesa M.; Delton, Isabelle; Luquain-Costaz, Céline (2019)
    Bis(Monoacylglycero) Phosphate (BMP) is a unique phospholipid localized in late endosomes, a critical cellular compartment in low density lipoprotein (LDL)-cholesterol metabolism. In previous work, we demonstrated the important role of BMP in the regulation of macrophage cholesterol homeostasis. BMP exerts a protective role against the pro-apoptotic effect of oxidized LDL (oxLDL) by reducing the production of deleterious oxysterols. As the intracellular sterol traffic in macrophages is in part regulated by oxysterol binding protein (OSBP) and OSBP-related proteins (ORPs), we investigated the role of ORP11, localized at the Golgi-late endosomes interface, in the BMP-mediated protection from oxLDL/oxysterol cytotoxicity. Stably silencing of ORP11 in mouse RAW264.7 macrophages via a shRNA lentiviruses system had no effect on BMP production. However, ORP11 knockdown abrogated the protective action of BMP against oxLDL induced apoptosis. In oxLDL treated control cells, BMP enrichment was associated with reduced generation of 7-oxysterols, while these oxysterol species were abundant in the ORP11 knock-down cells. Of note, BMP enrichment in ORP11 knock-down cells was associated with a drastic increase in free cholesterol and linked to a decrease of cholesterol efflux. The expression of ATP-binding cassette-transporter G1 (ABCG1) was also reduced in the ORP11 knock-down cells. These observations demonstrate a cooperative function of OPR11 and BMP, in intracellular cholesterol trafficking in cultured macrophages. We suggest that BMP favors the egress of cholesterol from late endosomes via an ORP11-dependent mechanism, resulting in a reduced production of cytotoxic 7-oxysterols.
  • Karaman, Sinem; Hollmen, Maija; Robciuc, Marius R.; Alitalo, Annamari; Nurmi, Harri; Morf, Bettina; Buschle, Dorina; Alkan, H. Furkan; Ochsenbein, Alexandra M.; Alitalo, Kari; Wolfrum, Christian; Detmar, Michael (2015)
    Objective: Elevated serum levels of the lymphangiogenic factors VEGF-C and -D have been observed in obese individuals but their relevance for the metabolic syndrome has remained unknown. Methods: K14-VEGFR-3-Ig (sR3) mice that constitutively express soluble-VEGFR-3eIg in the skin, scavenging VEGF-C and -D, and wildtype (WT) mice were fed either chow or high-fat diet for 20 weeks. To assess the effect of VEGFR-3 blockage on adipose tissue growth and insulin sensitivity, we evaluated weight gain, adipocyte size and hepatic lipid accumulation. These results were complemented with insulin tolerance tests, FACS analysis of adipose tissue macrophages, in vitro 3T3-L1 differentiation assays and in vivo blocking antibody treatment experiments. Results: We show here that sR3 mice are protected from obesity-induced insulin resistance and hepatic lipid accumulation. This protection is associated with enhanced subcutaneous adipose tissue hyperplasia and an increased number of alternatively-activated (M2) macrophages in adipose tissue. We also show that VEGF-C and -D are chemotactic for murine macrophages and that this effect is mediated by VEGFR-3, which is upregulated on M1 polarized macrophages. Systemic antibody blockage of VEGFR-3 in db/db mice reduces adipose tissue macrophage infiltration and hepatic lipid accumulation, and improves insulin sensitivity. Conclusions: These results reveal an unanticipated role of the lymphangiogenic factors VEGF-C and -D in the mediation of metabolic syndrome-associated adipose tissue inflammation. Blockage of these lymphangiogenic factors might constitute a new therapeutic strategy for the prevention of obesity-associated insulin resistance. (C) 2014 The Authors. Published by Elsevier GmbH.
  • Barreto, Goncalo; Senturk, B.; Colombo, L.; Brück, O.; Neidenbach, P.; Salzmann, G.; Zenobi-Wong, M.; Rottmar, M. (2020)
    Objective: Lumican (LUM) is a major extracellular matrix glycoprotein in adult articular cartilage and its expression is known to be upregulated upon cartilage degeneration. LUM is associated with the pathogen-associated molecular pattern (PAMP) activation of the TLR4 signalling cascade, with TLR4 being highly associated with inflammation in rheumatic diseases. However, the main role of the LUM structural molecule in osteoarthritis (OA) remains elusive. The aim of this study was, therefore, to understand the role of LUM during TLR4-mediated activation in OA. Methods: After measuring LUM levels in synovial fluid (SF) of OA patients and lipopolysaccharide (LPS)-induced TLR4 activation, the role of LUM in the expression of pro-inflammatory molecules and cartilage degradation was assessed in vitro and ex vivo in a cartilage explant model. Primary macrophage activation and polarization were studied upon LUM co-stimulation with LPS. Results: We demonstrate that LUM is not only significantly upregulated in SF from OA patients compared to healthy controls, but also that LUM increases lipopolysaccharide (LPS)-induced TLR4 activation. Furthermore, we show that a pathophysiological level of LUM augments the LPS-induced TLR4 activation and expression of downstream pro-inflammatory molecules, resulting in extensive cartilage degradation. LUM co-stimulation with LPS also provided a pro-inflammatory stimulus, upregulating primary macrophage activation and polarization towards the M1-like phenotype. Conclusions: These findings strongly support the role of LUM as a mediator of PAMP-induced TLR4 activation of inflammation, cartilage degradation, and macrophage polarization in the OA joint and potentially other rheumatic diseases. (C) 2019 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.
  • Nathan, K.; Lu, L. Y.; Lin, T.; Pajarinen, J.; Jämsen, E.; Huang, J-F; Romero-Lopez, M.; Maruyama, M.; Kohno, Y.; Yao, Z.; Goodman, S. B. (2019)
    Objectives Up to 10% of fractures result in undesirable outcomes, for which female sex is a risk factor. Cellular sex differences have been implicated in these different healing processes. Better understanding of the mechanisms underlying bone healing and sex differences in this process is key to improved clinical outcomes. This study utilized a macrophage-mesenchymal stem cell (MSC) coculture system to determine: 1) the precise timing of proinflammatory (M1) to anti-inflammatory (M2) macrophage transition for optimal bone formation; and 2) how such immunomodulation was affected by male versus female cocultures. Methods A primary murine macrophage-MSC coculture system was used to demonstrate the optimal transition time from M1 to M2 (polarized from M1 with interleukin (IL)-4) macrophages to maximize matrix mineralization in male and female MSCs. Outcome variables included Alizarin Red staining, alkaline phosphatase (ALP) activity, and osteocalcin protein secretion. Results We found that 96 hours of M1 phenotype in male cocultures allowed for maximum matrix mineralization versus 72 hours in female cocultures. ALP activity and osteocalcin secretion were also enhanced with the addition of IL-4 later in male versus female groups. The sex of the cells had a statistically significant effect on the optimal IL-4 addition time to maximize osteogenesis. Conclusion These results suggest that: 1) a 72- to 96-hour proinflammatory environment is critical for optimal matrix mineralization; and 2) there are immunological differences in this coculture environment due to sex. Optimizing immunomodulation during fracture healing may enhance and expedite the bone regeneration response. These findings provide insight into precise immunomodulation for enhanced bone healing that is sex-specific.
  • Chen, Lu; Zhang, Liucheng; Zhang, Hongbo; Sun, Xiaoming; Liu, Dan; Zhang, Jianming; Zhang, Yuguang; Cheng, Liying; Santos, Hélder A.; Cui, Wenguo (2021)
    Immune cells play a crucial regulatory role in inflammatory phase and proliferative phase during skin healing. How to programmatically activate sequential immune responses is the key for scarless skin regeneration. In this study, an “Inner-Outer” IL-10-loaded electrospun fiber with cascade release behavior was constructed. During the inflammatory phase, the electrospun fiber released a lower concentration of IL-10 within the wound, inhibiting excessive recruitment of inflammatory cells and polarizing macrophages into anti-inflammatory phenotype “M2c” to suppress excessive inflammation response. During the proliferative phase, a higher concentration of IL-10 released by the fiber and the anti-fibrotic cytokines secreted by polarized “M2c” directly acted on dermal fibroblasts to simultaneously inhibit extracellular matrix overdeposition and promote fibroblast migration. The “Inner-Outer” IL-10-loaded electrospun fiber programmatically activated the sequential immune responses during wound healing and led to scarless skin regeneration, which is a promising immunomodulatory biomaterial with great potential for promoting complete tissue regeneration.
  • Tulamo, Riikka; Mäyränpää, Mikko I.; Aho, Pekka (2019)
  • Salmiheimo, Aino; Mustonen, Harri; Vainionpaa, Sanna; Shen, Zhanlong; Kemppainen, Esko; Puolakkainen, Pauli; Seppanen, Hanna (2017)
    Objectives: Tumour-associated macrophages participate in tumour development and progression. The aim of this study was to assess the interactions of pancreatic cancer cells and pro-inflammatory M1 and anti-inflammatory M2 macrophages, specifically their effect on pancreatic cancer cell migration and the changes in STAT-signalling. Methods: Monocytes were isolated from healthy subjects and differentiated into macrophages with M-CSF. The macrophages were polarized towards M1 by IL-12 and towards M2 by IL-10. We studied also the effect of pan-JAK/STAT-inhibitor P6. Macrophage polarization and STAT and NF kappa B-activation in both MiaPaCa-2 and macrophages were assessed by flow cytometry. We recorded the effect of co-culture on migration rate of pancreatic cancer cells MiaPaCa-2. Results: Macrophages increased the migration rate of pancreatic cancer cells. Co-culture activated STAT1, STAT3, STAT5, AKT and NF kappa B in macrophages and STAT3 in MiaPaCa-2 cells. IL-12 polarized macrophages towards M1 and decreased the migration rate of pancreatic cancer cells in co-cultures as well as P6. IL-10 skewed macrophage polarization towards M2 and induced increase of pancreatic cancer cells in co-cultures. Conclusion: Co-culture with macrophages increased pancreatic cancer cell migration and activated STAT3. It is possible to activate and deactivate migration of pancreatic cancer cells trough macrophage polarization. (C) 2017 IAP and EPC. Published by Elsevier B.V. All rights reserved.