Low-intensity pulsed ultrasound restores mitochondrial dynamics and function in lipopolysaccharide-stimulated astrocytes

Background: Low-intensity pulsed ultrasound (LIPUS) is a non-invasive therapeutic modality with growing potential in the treatment of neurodegenerative diseases. However, its mechanistic role in regulating mitochondrial homeostasis in astrocytes under inflammatory stress remains poorly understood. This study aimed to investigate the effects of LIPUS on mitochondrial dynamics, morphology, oxidative stress, mitochondrial membrane potential, and mitochondrial stress response in an in vitro model of neuroinflammation. Methods: Normal Human Astrocytes (NHA) were stimulated with lipopolysaccharide (LPS; 0.5 µg/mL, 24 h) and subsequently treated with LIPUS (1 MHz, 50% duty cycle, 100 Hz, 15 min) at intensities of 100, 300, or 500 mW/cm2. The expression of mitochondrial fusion (MFN1, MFN2, OPA1) and fission (DRP1, FIS1) markers was analyzed using qPCR. Mitochondrial morphology was evaluated by confocal microscopy, while reactive oxygen species (ROS) levels and mitochondrial membrane potential (ΔΨm) were measured using specific fluorescent probes. Expression of mitochondrial stress-related genes (PGC1α, CLPP, HSP60, LONP1) was also assessed. Results: LIPUS treatment, particularly at 300 mW/cm2, significantly enhanced the expression of mitochondrial fusion markers while suppressing fission markers in a dose- and time-dependent manner, with peak effects observed 4 h post-treatment. Confocal imaging revealed that LIPUS mitigated LPS-induced mitochondrial fragmentation. Additionally, LIPUS reduced ROS accumulation, preserved ΔΨm, and attenuated the LPS-induced upregulation of mitochondrial stress-related genes, suggesting modulation of both stress response and biogenesis. Conclusion: LIPUS ameliorates mitochondrial dysfunction in inflamed astrocytes by restoring mitochondrial dynamics and reducing stress signaling, supporting its potential as a therapeutic strategy for neuroinflammation-associated neurodegenerative disorders.