Article
Effects of hypoxia and signals from activated B cells on functions of multipotent mesenchymal stromal cells
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Authors
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Roberta Scarpone
- Universitätsklinikum Heidelberg, Medizinische Klinik V, Sektion Rheumatologie, Heidelberg
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Panagiotis Gitsioudis
- Universitätsklinikum Heidelberg, Medizinische Klinik V, Sektion Rheumatologie, Heidelberg
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Rainer Saffrich
- Universitätsklinikum Heidelberg, Medizinische Klinik V, Sektion Hämatologie und Onkologie, Heidelberg
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Lars-Oliver Tykocinski
- Universitätsklinikum Heidelberg, Medizinische Klinik V, Sektion Rheumatologie, Heidelberg
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Hanns-Martin Lorenz
- Universitätsklinikum Heidelberg, Medizinische Klinik V, Sektion Rheumatologie, Heidelberg
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Theresa Tretter
- Universitätsklinikum Heidelberg, Medizinische Klinik V, Sektion Rheumatologie, Heidelberg
| Published: | February 5, 2019 |
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Outline
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Background: Multipotent mesenchymal stromal cells (MSCs) are a promising approach for the treatment of chronic inflammatory autoimmune diseases. However, little is known whether the pathogenic environment influences their replicative and regenerative potential.
Activated lymphocytes and hypoxia are part of the cellular environment in chronic inflammatory diseases. The aim of this study was to investigate the influence of activated B cells and hypoxia on MSC functions.
Methods: B cells from peripheral blood of healthy donors were separated by density gradient centrifugation and magnetic cell sorting. Bone marrow MSCs from healthy donors were cultured for various time periods under normoxia or hypoxia (3%), alone or in coculture with B cells, activated via B cell receptor cross-linking and IL-2. Alternatively cell culture supernatant from 3d activated B cells was used. Cell division, expression of surface markers, cytokine secretion and gene expression was assessed by flow cytometry, ELISA and qRT-PCR. For differentiation assays MSCs were cultured for 21 days in differentiation media with or without B cell culture supernatant and osteogenic and adipogenic differentiation was examined by means of fluorescence microscopy.
Results: Coculture with activated B cells led to a significant increase of IL-6 and IL-8 production in MSCs both under normoxic and hypoxic conditions. In contrast B cell specific TNF-alpha production and proliferation was reduced by more than half, demonstrating suppression of B cell activation in return by activated MSC. This was observed both in direct cell contact and upon separation by cell culture inserts, suggesting soluble factors were sufficient to convey effects. In addition B cells induced a significant increase of MSC proliferation and delayed entry into senescence, which wasfurther supported by hypoxia. Soluble B cell factors induced MSC-specific expression of hypoxia-induced transcription factor HIF-1alpha under normoxic conditions. Further, they selectively promoted MSC differentiation towards the osteogenic lineage under normoxia as well ashypoxia.
Conclusion: These results suggest an important influence of the inflammatory environment on MSC functions: In presence of activated B cells MSC exert immunosuppressive properties but also secrete high amounts of proinflammatory cytokines. They increase their replicative potential and preferentially differentiate into the osteogenic lineage, both under normoxia and hypoxia.
