Mitochondrial‐Mediated Platelet Activation in Polymyalgia Rheumatica

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Autori principali: Despina Michailidou, Linda Johansson, Jorge Armando Gonzalez Chapa, Ting Wang, Junmei Chen, José A. López, Solbritt Rantapää‐Dahlqvist, Christian Lood
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Pubblicazione: Wiley 2025
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author Despina Michailidou
Linda Johansson
Jorge Armando Gonzalez Chapa
Ting Wang
Junmei Chen
José A. López
Solbritt Rantapää‐Dahlqvist
Christian Lood
author_facet Despina Michailidou
Linda Johansson
Jorge Armando Gonzalez Chapa
Ting Wang
Junmei Chen
José A. López
Solbritt Rantapää‐Dahlqvist
Christian Lood
Despina Michailidou
Linda Johansson
Jorge Armando Gonzalez Chapa
Ting Wang
Junmei Chen
José A. López
Solbritt Rantapää‐Dahlqvist
Christian Lood
collection Wiley Open Access
contents Mitochondrial‐Mediated Platelet Activation in Polymyalgia Rheumatica Despina Michailidou Linda Johansson Jorge Armando Gonzalez Chapa Ting Wang Junmei Chen José A. López Solbritt Rantapää‐Dahlqvist Christian Lood ACR Open Rheumatology ObjectivePlatelet activation is thought to participate in polymyalgia rheumatica (PMR) pathogenesis. Upon platelet activation, mitochondria are expelled into the extracellular space. However, whether extracellular mitochondria are present in patients with PMR and whether they can induce platelet activation is not known.MethodsTo investigate this, we measured markers of platelet activation (thrombospondin‐1 [TSP‐1]), mitochondrial‐derived N‐formyl methionine peptide (fMET), and autoantibodies directed toward specific mitochondrial antigen mitofusin‐1 (MFN1) by enzyme‐linked immunosorbent assay in plasma of healthy controls (HCs, n = 30) and patients with PMR without giant cell arteritis (GCA) (n = 45) and patients with PMR with GCA (n = 9) before and after treatment with glucocorticoid therapy. Ultrapure mitochondria were opsonized with plasma from patients with PMR without GCA (n = 45) or HCs (n = 10) and were subsequently incubated with HC platelets. Platelet activation was assessed by P‐selectin levels using flow cytometry.ResultsPlasma levels of anti‐MFN1 IgG were elevated in patients with PMR with and without GCA before glucocorticoid therapy when compared with HCs (P < 0.01 for both groups). Levels of anti‐MFN1 IgG significantly reduced after treatment with glucocorticoids in both groups (P < 0.01). Levels of fMET were also significantly higher in patients with PMR with and without GCA before glucocorticoid therapy in comparison with HCs (P < 0.001 and P < 0.01, respectively). However, the levels of fMET only dropped significantly after therapy in patients with PMR without GCA (P < 0.001). Plasma levels of TSP‐1 were elevated in patients with PMR with and without GCA before glucocorticoid therapy when compared to HC (P < 0.001 for both groups). After glucocorticoid therapy, plasma levels of TSP‐1 decreased significantly only in patients with PMR without GCA (P = 0.023). Mitochondria opsonized with plasma from patients with PMR without GCA induced higher platelet activation regardless of treatment status as compared with plasma from HCs (P < 0.0001 and P < 0.01 for pretreatment and posttreatment).ConclusionOur results indicate increased platelet activation and the presence of mitochondrial antigens and antibodies in the circulation of patients with PMR. Blocking mitochondrial‐mediated platelet activation may reduce inflammation in patients with PMR, with potential therapeutic implications.image 10.1002/acr2.70021 http://creativecommons.org/licenses/by-nc/4.0/
doi_str_mv 10.1002/acr2.70021
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id wiley_oa_10_1002_acr2_70021
institution Wiley Open Access
license_str_mv http://creativecommons.org/licenses/by-nc/4.0/
publishDate 2025
publisher Wiley
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spellingShingle Mitochondrial‐Mediated Platelet Activation in Polymyalgia Rheumatica
Despina Michailidou
Linda Johansson
Jorge Armando Gonzalez Chapa
Ting Wang
Junmei Chen
José A. López
Solbritt Rantapää‐Dahlqvist
Christian Lood
ACR Open Rheumatology
Mitochondrial‐Mediated Platelet Activation in Polymyalgia Rheumatica Despina Michailidou Linda Johansson Jorge Armando Gonzalez Chapa Ting Wang Junmei Chen José A. López Solbritt Rantapää‐Dahlqvist Christian Lood ACR Open Rheumatology ObjectivePlatelet activation is thought to participate in polymyalgia rheumatica (PMR) pathogenesis. Upon platelet activation, mitochondria are expelled into the extracellular space. However, whether extracellular mitochondria are present in patients with PMR and whether they can induce platelet activation is not known.MethodsTo investigate this, we measured markers of platelet activation (thrombospondin‐1 [TSP‐1]), mitochondrial‐derived N‐formyl methionine peptide (fMET), and autoantibodies directed toward specific mitochondrial antigen mitofusin‐1 (MFN1) by enzyme‐linked immunosorbent assay in plasma of healthy controls (HCs, n = 30) and patients with PMR without giant cell arteritis (GCA) (n = 45) and patients with PMR with GCA (n = 9) before and after treatment with glucocorticoid therapy. Ultrapure mitochondria were opsonized with plasma from patients with PMR without GCA (n = 45) or HCs (n = 10) and were subsequently incubated with HC platelets. Platelet activation was assessed by P‐selectin levels using flow cytometry.ResultsPlasma levels of anti‐MFN1 IgG were elevated in patients with PMR with and without GCA before glucocorticoid therapy when compared with HCs (P < 0.01 for both groups). Levels of anti‐MFN1 IgG significantly reduced after treatment with glucocorticoids in both groups (P < 0.01). Levels of fMET were also significantly higher in patients with PMR with and without GCA before glucocorticoid therapy in comparison with HCs (P < 0.001 and P < 0.01, respectively). However, the levels of fMET only dropped significantly after therapy in patients with PMR without GCA (P < 0.001). Plasma levels of TSP‐1 were elevated in patients with PMR with and without GCA before glucocorticoid therapy when compared to HC (P < 0.001 for both groups). After glucocorticoid therapy, plasma levels of TSP‐1 decreased significantly only in patients with PMR without GCA (P = 0.023). Mitochondria opsonized with plasma from patients with PMR without GCA induced higher platelet activation regardless of treatment status as compared with plasma from HCs (P < 0.0001 and P < 0.01 for pretreatment and posttreatment).ConclusionOur results indicate increased platelet activation and the presence of mitochondrial antigens and antibodies in the circulation of patients with PMR. Blocking mitochondrial‐mediated platelet activation may reduce inflammation in patients with PMR, with potential therapeutic implications.image 10.1002/acr2.70021 http://creativecommons.org/licenses/by-nc/4.0/
title Mitochondrial‐Mediated Platelet Activation in Polymyalgia Rheumatica
topic ACR Open Rheumatology
url https://acrjournals.onlinelibrary.wiley.com/doi/10.1002/acr2.70021