RESUMO
Neurodegenerative disorders alter mitochondrial functions, including the production of reactive oxygen species (ROS). Mitochondrial complex III (CIII) generates ROS implicated in redox signaling, but its triggers, targets, and disease relevance are not clear. Using site-selective suppressors and genetic manipulations together with mitochondrial ROS imaging and multiomic profiling, we found that CIII is the dominant source of ROS production in astrocytes exposed to neuropathology-related stimuli. Astrocytic CIII-ROS production was dependent on nuclear factor-κB (NF-κB) and the mitochondrial sodium-calcium exchanger (NCLX) and caused oxidation of select cysteines within immune and metabolism-associated proteins linked to neurological disease. CIII-ROS amplified metabolomic and pathology-associated transcriptional changes in astrocytes, with STAT3 activity as a major mediator, and facilitated neuronal toxicity in a non-cell-autonomous manner. As proof-of-concept, suppression of CIII-ROS in mice decreased dementia-linked tauopathy and neuroimmune cascades and extended lifespan. Our findings establish CIII-ROS as an important immunometabolic signal transducer and tractable therapeutic target in neurodegenerative disease.
RESUMO
BACKGROUND AND OBJECTIVES: Perihematomal edema (PHE) contributes to poor outcome after deep intraparenchymal hemorrhage (IPH), which is characterized by neuroinflammation and an influx of peripherally derived innate immune cells. We previously identified soluble ST2 (sST2) as a candidate for immune-mediated secondary brain injury. Leveraging prospectively collected cohorts from 2 centers, we sought to determine whether sST2 was associated with functional outcome, PHE, and the immune response following IPH. METHODS: Patients with deep IPH were enrolled within 36 hours of ictus, and blood was collected for sST2 and immune cell measurement. Hematoma volume and PHE were measured on serial CT scans. Good outcome was defined as a modified Rankin Scale score of 0-3 at 90 days. Linear mixed-effects models were used to analyze the relationship between sST2 and PHE over time. Flow cytometry was used to identify shifts in immune cell populations associated with sST2. Immunohistochemistry of human brain tissue was used to identify ST2-expressing cells in the perihematomal region. RESULTS: The 55 included patients had a median admission Glasgow Coma Scale score of 14 (interquartile range [IQR] 9-15), an intracerebral hemorrhage (ICH) score of 1 (IQR 1-2), and a hematoma volume of 8.6 mL (IQR 3.4-13.8 mL). Receiver operating curve analysis found the sST2 level to be predictive of poor outcome with an area under the curve of 0.763 (95% CI 0.632-0.894) and Youden optimum cut point of 61.8 ng/mL (p < 0.001). sST2 remained an independent predictor after adjustment for ICH score (adjusted odds ratio 2.53, 95% CI 1.03-6.19, p = 0.042). Measurement of PHE found those patients with high sST2 to have greater edema volume over time (ß = 1.07, 95% CI 0.51-1.63, p < 0.001). High sST2 was associated with a shift toward an innate peripheral immune response (monocytes and natural killer cells; 68.6% ± 5.1% vs 47.5% ± 4.0%; p = 0.003). DISCUSSION: Our findings demonstrate that elevated sST2 links the peripheral innate immune response to PHE volume and outcome after IPH. This knowledge is relevant to future studies that seek to identify patients with IPH at highest risk for immune-mediated injury or limit injury through targeted interventions.