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Efferocytosis is restricted by axon guidance molecule EphA4 via ERK/Stat6/MERTK signaling following brain injury

BACKGROUND: Efferocytosis is a process that removes apoptotic cells and cellular debris. Clearance of these cells alleviates neuroinflammation, prevents the release of inflammatory molecules, and promotes the production of anti-inflammatory cytokines to help maintain tissue homeostasis. The underlyi...

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Autores principales: Soliman, Eman, Leonard, John, Basso, Erwin Kristobal Gudenschwager, Gershenson, Ilana, Ju, Jing, Mills, Jatia, de Jager, Caroline, Kaloss, Alexandra M., Elhassanny, Mohamed, Pereira, Daniela, Chen, Michael, Wang, Xia, Theus, Michelle H.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10633953/
https://www.ncbi.nlm.nih.gov/pubmed/37941008
http://dx.doi.org/10.1186/s12974-023-02940-5
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author Soliman, Eman
Leonard, John
Basso, Erwin Kristobal Gudenschwager
Gershenson, Ilana
Ju, Jing
Mills, Jatia
de Jager, Caroline
Kaloss, Alexandra M.
Elhassanny, Mohamed
Pereira, Daniela
Chen, Michael
Wang, Xia
Theus, Michelle H.
author_facet Soliman, Eman
Leonard, John
Basso, Erwin Kristobal Gudenschwager
Gershenson, Ilana
Ju, Jing
Mills, Jatia
de Jager, Caroline
Kaloss, Alexandra M.
Elhassanny, Mohamed
Pereira, Daniela
Chen, Michael
Wang, Xia
Theus, Michelle H.
author_sort Soliman, Eman
collection PubMed
description BACKGROUND: Efferocytosis is a process that removes apoptotic cells and cellular debris. Clearance of these cells alleviates neuroinflammation, prevents the release of inflammatory molecules, and promotes the production of anti-inflammatory cytokines to help maintain tissue homeostasis. The underlying mechanisms by which this occurs in the brain after injury remain ill-defined. METHODS: We used GFP bone marrow chimeric knockout (KO) mice to demonstrate that the axon guidance molecule EphA4 receptor tyrosine kinase is involved in suppressing MERTK in the brain to restrict efferocytosis of resident microglia and peripheral-derived monocyte/macrophages. RESULTS: Single-cell RNAseq identified MERTK expression, the primary receptor involved in efferocytosis, on monocytes, microglia, and a subset of astrocytes in the damaged cortex following brain injury. Loss of EphA4 on infiltrating GFP-expressing immune cells improved functional outcome concomitant with enhanced efferocytosis and overall protein expression of p-MERTK, p-ERK, and p-Stat6. The percentage of GFP(+) monocyte/macrophages and resident microglia engulfing NeuN(+) or TUNEL(+) cells was significantly higher in KO chimeric mice. Importantly, mRNA expression of Mertk and its cognate ligand Gas6 was significantly elevated in these mice compared to the wild-type. Analysis of cell-specific expression showed that p-ERK and p-Stat6 co-localized with MERTK-expressing GFP + cells in the peri-lesional area of the cortex following brain injury. Using an in vitro efferocytosis assay, co-culturing pHrodo-labeled apoptotic Jurkat cells and bone marrow (BM)-derived macrophages, we demonstrate that efferocytosis efficiency and mRNA expression of Mertk and Gas6 was enhanced in the absence of EphA4. Selective inhibitors of ERK and Stat6 attenuated this effect, confirming that EphA4 suppresses monocyte/macrophage efferocytosis via inhibition of the ERK/Stat6 pathway. CONCLUSIONS: Our findings implicate the ERK/Stat6/MERTK axis as a novel regulator of apoptotic debris clearance in brain injury that is restricted by peripheral myeloid-derived EphA4 to prevent the resolution of inflammation. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12974-023-02940-5.
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spelling pubmed-106339532023-11-10 Efferocytosis is restricted by axon guidance molecule EphA4 via ERK/Stat6/MERTK signaling following brain injury Soliman, Eman Leonard, John Basso, Erwin Kristobal Gudenschwager Gershenson, Ilana Ju, Jing Mills, Jatia de Jager, Caroline Kaloss, Alexandra M. Elhassanny, Mohamed Pereira, Daniela Chen, Michael Wang, Xia Theus, Michelle H. J Neuroinflammation Research BACKGROUND: Efferocytosis is a process that removes apoptotic cells and cellular debris. Clearance of these cells alleviates neuroinflammation, prevents the release of inflammatory molecules, and promotes the production of anti-inflammatory cytokines to help maintain tissue homeostasis. The underlying mechanisms by which this occurs in the brain after injury remain ill-defined. METHODS: We used GFP bone marrow chimeric knockout (KO) mice to demonstrate that the axon guidance molecule EphA4 receptor tyrosine kinase is involved in suppressing MERTK in the brain to restrict efferocytosis of resident microglia and peripheral-derived monocyte/macrophages. RESULTS: Single-cell RNAseq identified MERTK expression, the primary receptor involved in efferocytosis, on monocytes, microglia, and a subset of astrocytes in the damaged cortex following brain injury. Loss of EphA4 on infiltrating GFP-expressing immune cells improved functional outcome concomitant with enhanced efferocytosis and overall protein expression of p-MERTK, p-ERK, and p-Stat6. The percentage of GFP(+) monocyte/macrophages and resident microglia engulfing NeuN(+) or TUNEL(+) cells was significantly higher in KO chimeric mice. Importantly, mRNA expression of Mertk and its cognate ligand Gas6 was significantly elevated in these mice compared to the wild-type. Analysis of cell-specific expression showed that p-ERK and p-Stat6 co-localized with MERTK-expressing GFP + cells in the peri-lesional area of the cortex following brain injury. Using an in vitro efferocytosis assay, co-culturing pHrodo-labeled apoptotic Jurkat cells and bone marrow (BM)-derived macrophages, we demonstrate that efferocytosis efficiency and mRNA expression of Mertk and Gas6 was enhanced in the absence of EphA4. Selective inhibitors of ERK and Stat6 attenuated this effect, confirming that EphA4 suppresses monocyte/macrophage efferocytosis via inhibition of the ERK/Stat6 pathway. CONCLUSIONS: Our findings implicate the ERK/Stat6/MERTK axis as a novel regulator of apoptotic debris clearance in brain injury that is restricted by peripheral myeloid-derived EphA4 to prevent the resolution of inflammation. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12974-023-02940-5. BioMed Central 2023-11-09 /pmc/articles/PMC10633953/ /pubmed/37941008 http://dx.doi.org/10.1186/s12974-023-02940-5 Text en © The Author(s) 2023 https://creativecommons.org/licenses/by/4.0/Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ (https://creativecommons.org/licenses/by/4.0/) . The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/ (https://creativecommons.org/publicdomain/zero/1.0/) ) applies to the data made available in this article, unless otherwise stated in a credit line to the data.
spellingShingle Research
Soliman, Eman
Leonard, John
Basso, Erwin Kristobal Gudenschwager
Gershenson, Ilana
Ju, Jing
Mills, Jatia
de Jager, Caroline
Kaloss, Alexandra M.
Elhassanny, Mohamed
Pereira, Daniela
Chen, Michael
Wang, Xia
Theus, Michelle H.
Efferocytosis is restricted by axon guidance molecule EphA4 via ERK/Stat6/MERTK signaling following brain injury
title Efferocytosis is restricted by axon guidance molecule EphA4 via ERK/Stat6/MERTK signaling following brain injury
title_full Efferocytosis is restricted by axon guidance molecule EphA4 via ERK/Stat6/MERTK signaling following brain injury
title_fullStr Efferocytosis is restricted by axon guidance molecule EphA4 via ERK/Stat6/MERTK signaling following brain injury
title_full_unstemmed Efferocytosis is restricted by axon guidance molecule EphA4 via ERK/Stat6/MERTK signaling following brain injury
title_short Efferocytosis is restricted by axon guidance molecule EphA4 via ERK/Stat6/MERTK signaling following brain injury
title_sort efferocytosis is restricted by axon guidance molecule epha4 via erk/stat6/mertk signaling following brain injury
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10633953/
https://www.ncbi.nlm.nih.gov/pubmed/37941008
http://dx.doi.org/10.1186/s12974-023-02940-5
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