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Autophagy Induces Expression of IL-6 in Human Periodontal Ligament Fibroblasts Under Mechanical Load and Overload and Effects Osteoclastogenesis in vitro

Objective: Autophagy is an important cellular adaptation mechanism to mechanical stress. In animal experiments, inhibition of autophagy during orthodontic tooth movement triggered increased expression of inflammation-related genes and decreased bone density. The aim of this study was to investigate...

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Autores principales: Mayr, Alexandra, Marciniak, Jana, Eggers, Benedikt, Blawat, Kim, Wildenhof, Jan, Bastos Craveiro, Rogerio, Wolf, Michael, Deschner, James, Jäger, Andreas, Beisel-Memmert, Svenja
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2021
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Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8430222/
https://www.ncbi.nlm.nih.gov/pubmed/34512388
http://dx.doi.org/10.3389/fphys.2021.716441
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author Mayr, Alexandra
Marciniak, Jana
Eggers, Benedikt
Blawat, Kim
Wildenhof, Jan
Bastos Craveiro, Rogerio
Wolf, Michael
Deschner, James
Jäger, Andreas
Beisel-Memmert, Svenja
author_facet Mayr, Alexandra
Marciniak, Jana
Eggers, Benedikt
Blawat, Kim
Wildenhof, Jan
Bastos Craveiro, Rogerio
Wolf, Michael
Deschner, James
Jäger, Andreas
Beisel-Memmert, Svenja
author_sort Mayr, Alexandra
collection PubMed
description Objective: Autophagy is an important cellular adaptation mechanism to mechanical stress. In animal experiments, inhibition of autophagy during orthodontic tooth movement triggered increased expression of inflammation-related genes and decreased bone density. The aim of this study was to investigate how autophagy affects cytokine levels of interleukin 6 (IL-6) in human periodontal ligament (hPDL) fibroblasts under mechanical pressure and the resulting influence on osteoblast communication. Methods: hPDL fibroblasts were subjected to physiologic mechanical load, constant overload, or rapamycin treatment for 16 to 24 h ± autophagy inhibitor 3-MA. Autophagosomes were quantified by flow cytometry. Gene expression of il-6 as well as IL-6 levels in the supernatant were determined with rtPCR and ELISA. To investigate the influence of mechanically-induced autophagy on cell-cell communication, an osteoblast-culture was subjected to supernatant from stimulated hPDL fibroblasts ± soluble IL-6 receptor (sIL-6R). After 24 h, osteoprotegerin (opg) and receptor activator of nuclear factor κB ligand (rankl) gene expressions were detected with rtPCR. Gene expression of a disintegrin and metalloproteinases (adam) 10 and 17 in stimulated hPDL fibroblasts was examined via rtPCR. Results: Autophagy was induced by biomechanical stress in hPDL fibroblasts in a dose-dependent manner. Mechanical load and overload increased IL-6 expression at gene and protein level. Autophagy inhibition further enhanced the effects of mechanical stimulation on IL-6 expression. Mechanical stimulation of hPDL fibroblasts downregulated adam10 and adam17 expressions. Inhibition of autophagy had stimulus-intensity depending effects: autophagy inhibition alone or additional application of physiological stress enhanced adam10 and adam17 expressions, whereas mechanical overload had adverse effects. Osteoblasts showed significantly reduced opg expression in the presence of supernatant derived of hPDL fibroblasts treated with autophagy inhibitor and sIL-6R. Conclusion: IL-6 levels were increased in response to pressure in hPDL fibroblasts, which was further enhanced by autophagy inhibition. This caused a decrease in opg expression in osteoblasts. This may serve as an explanatory model for accelerated tooth movement observed under autophagy inhibition, but may also represent a risk factor for uncontrolled bone loss.
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spelling pubmed-84302222021-09-11 Autophagy Induces Expression of IL-6 in Human Periodontal Ligament Fibroblasts Under Mechanical Load and Overload and Effects Osteoclastogenesis in vitro Mayr, Alexandra Marciniak, Jana Eggers, Benedikt Blawat, Kim Wildenhof, Jan Bastos Craveiro, Rogerio Wolf, Michael Deschner, James Jäger, Andreas Beisel-Memmert, Svenja Front Physiol Physiology Objective: Autophagy is an important cellular adaptation mechanism to mechanical stress. In animal experiments, inhibition of autophagy during orthodontic tooth movement triggered increased expression of inflammation-related genes and decreased bone density. The aim of this study was to investigate how autophagy affects cytokine levels of interleukin 6 (IL-6) in human periodontal ligament (hPDL) fibroblasts under mechanical pressure and the resulting influence on osteoblast communication. Methods: hPDL fibroblasts were subjected to physiologic mechanical load, constant overload, or rapamycin treatment for 16 to 24 h ± autophagy inhibitor 3-MA. Autophagosomes were quantified by flow cytometry. Gene expression of il-6 as well as IL-6 levels in the supernatant were determined with rtPCR and ELISA. To investigate the influence of mechanically-induced autophagy on cell-cell communication, an osteoblast-culture was subjected to supernatant from stimulated hPDL fibroblasts ± soluble IL-6 receptor (sIL-6R). After 24 h, osteoprotegerin (opg) and receptor activator of nuclear factor κB ligand (rankl) gene expressions were detected with rtPCR. Gene expression of a disintegrin and metalloproteinases (adam) 10 and 17 in stimulated hPDL fibroblasts was examined via rtPCR. Results: Autophagy was induced by biomechanical stress in hPDL fibroblasts in a dose-dependent manner. Mechanical load and overload increased IL-6 expression at gene and protein level. Autophagy inhibition further enhanced the effects of mechanical stimulation on IL-6 expression. Mechanical stimulation of hPDL fibroblasts downregulated adam10 and adam17 expressions. Inhibition of autophagy had stimulus-intensity depending effects: autophagy inhibition alone or additional application of physiological stress enhanced adam10 and adam17 expressions, whereas mechanical overload had adverse effects. Osteoblasts showed significantly reduced opg expression in the presence of supernatant derived of hPDL fibroblasts treated with autophagy inhibitor and sIL-6R. Conclusion: IL-6 levels were increased in response to pressure in hPDL fibroblasts, which was further enhanced by autophagy inhibition. This caused a decrease in opg expression in osteoblasts. This may serve as an explanatory model for accelerated tooth movement observed under autophagy inhibition, but may also represent a risk factor for uncontrolled bone loss. Frontiers Media S.A. 2021-08-27 /pmc/articles/PMC8430222/ /pubmed/34512388 http://dx.doi.org/10.3389/fphys.2021.716441 Text en Copyright © 2021 Mayr, Marciniak, Eggers, Blawat, Wildenhof, Bastos Craveiro, Wolf, Deschner, Jäger and Beisel-Memmert. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Physiology
Mayr, Alexandra
Marciniak, Jana
Eggers, Benedikt
Blawat, Kim
Wildenhof, Jan
Bastos Craveiro, Rogerio
Wolf, Michael
Deschner, James
Jäger, Andreas
Beisel-Memmert, Svenja
Autophagy Induces Expression of IL-6 in Human Periodontal Ligament Fibroblasts Under Mechanical Load and Overload and Effects Osteoclastogenesis in vitro
title Autophagy Induces Expression of IL-6 in Human Periodontal Ligament Fibroblasts Under Mechanical Load and Overload and Effects Osteoclastogenesis in vitro
title_full Autophagy Induces Expression of IL-6 in Human Periodontal Ligament Fibroblasts Under Mechanical Load and Overload and Effects Osteoclastogenesis in vitro
title_fullStr Autophagy Induces Expression of IL-6 in Human Periodontal Ligament Fibroblasts Under Mechanical Load and Overload and Effects Osteoclastogenesis in vitro
title_full_unstemmed Autophagy Induces Expression of IL-6 in Human Periodontal Ligament Fibroblasts Under Mechanical Load and Overload and Effects Osteoclastogenesis in vitro
title_short Autophagy Induces Expression of IL-6 in Human Periodontal Ligament Fibroblasts Under Mechanical Load and Overload and Effects Osteoclastogenesis in vitro
title_sort autophagy induces expression of il-6 in human periodontal ligament fibroblasts under mechanical load and overload and effects osteoclastogenesis in vitro
topic Physiology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8430222/
https://www.ncbi.nlm.nih.gov/pubmed/34512388
http://dx.doi.org/10.3389/fphys.2021.716441
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