1273 - Mitochondrial DNA Is Released as an Acute-phase Response of Chondrocytes to Induction of Mitochondrial Dysfunction
Year: 2019
Type: other
Abstract: evidence implicates mitochondrial dysfunction as an early link between cartilage injury and posttraumatic osteoarthritis (PTOA)- Cartilage impact injury results in acute, mechanically-mediated mitochondrialdysfunction, chondrocyte apoptosis, and extracellular matrix degeneration.1-3u2022 Mechanisms whereby injury-induced mitochondrial dysfunction may lead to ongoinginflammation and progressive joint degeneration are not clear.u2022 In other tissues, cellular stress and mitochondrial dysfunction trigger the releasemitochondria-specific Damage Associated Molecular Patterns (mDAMPs) into theextracellular milieu, which perpetuate inflammation and tissue damage.4u2022 This is the first evidence that mitochondrial dysfunction specifically induces mDAMP release by chondrocytes.u2022 mtDNA release induced by sub-lethal mitochondrial stressors peaks within 24 hours, then decreases once thestimulus is removed, indicating that mtDNA release is an acute-phase response of chondrocytes.u2022 This preliminary data suggest that inducing MT dysfunction, either by depolarizing the inner mitochondrialmembrane (FCCP) or inhibiting the electron transport chain (R/A), is the strongest stimulus for triggering acuteextracellular mtDNA release from viable chondrocytes.u2022 Both of these mechanisms have been implicated in acute mitochondrial dysfunction following cartilage trauma.1u2022 Future studies will investigate mDAMP release in response to cartilage impact injury ex vivo and in vivo.mtDNA is released from chondrocytes in response to sub-lethal cellular stressIn vitro model to study mDAMP release from chondrocytesu2022 Equine chondrocytes (P2, harvested and banked in liquidnitrogen, n=4) were cultured to ~90% confluence.u2022 Cells were stressed with either a general inflammatorystimulus (high-dose IL-1u03b2 1ng/ml or low-dose IL-1u03b2 10ng/ml),or one of three mitochondria-specific stressors:1) oligomycin (OLIGO; 1u03bcM) induces mitochondrialdysfunction by inhibiting ATP synthase,2) FCCP (1u03bcM), a proton circuit uncoupler, causesmitochondrial dysfunction by depolarizing the innermitochondrial membrane3) Rotenone + Antimycin A (R/A; 0.5u03bcM/0.5u03bcM) causemitochondrial dysfunction by inhibiting electron transportchain proteins complex I and III, respectively.u2022 Media was sampled at 24 hr post-stimulation, replaced,sampled at 48 hr and stored at -20ufffdufffdC until analysis.u2022 Equine-specific primers for 3 mtDNA genes (Cyt B, COX III,and NADH) and one nuclear gene (GAPDH) were designedand validated.DAMP, mitochondrial DNA (mtDNA), retains molecular motifs from itsprokaryotic origins that stimulate Toll-Like Receptor-9 when released extracellularly.5u2022 mDAMPs have not been studied in association with cartilage injury and OA.u2022 The goals were to investigate 1) mtDNA release from chondrocytes in response tocellular stress, 2) specific signals that initiate mtDNA release, 3) the time frame ofmtDNA release.
Authors: Michelle Delco, James Casey
Language: English
Subfield: Rheumatology
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W4391553148