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Updated: Aug 1, 2026
Pseudofracture: An Acute Peripheral Tissue Trauma Model
Published on: April 18, 2011
Fracture healing in a polytrauma rat model is influenced by mtDNA:cGAS complex mediated pro-inflammation
Preeti J Muire1,2, Alicia L Lofgren3, Stefanie M Shiels3
1Combat Wound Care, US Army Institute of Surgical Research, JBSA Ft Sam Houston, San Antonio, TX, 78234, USA. preetimuire@gmail.com.
Purpose:
The mitochondrial DNA (mtDNA) activated cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes (cGAS-STING) signaling pathway is a key player in mediating immune responses in autoimmune disorders and cancer. However, its role in severe trauma associated fracture healing is unknown. This study investigated if the cGAS-STING signaling pathway contributes to delayed bone healing in polytrauma (PT) fractures.
Methods:
For preliminary analyses, therapeutic dosage of RU.521 (cGAS inhibitor) (n = 2) was determined in C57BL/6 J mice by mass spectrometry, and IFNβ expression levels in serum and bronchioalveolar fluid (BALF) at 6 and 24 h (h) in RU.521/vehicle + mtDNA injected mice (n = 3/treatment and time point) was measured by ELISA. In the main study, plasma mtDNA was quantified by qPCR in a clinically relevant delayed fracture healing PT rat model with burn injury, blunt trauma, and a femoral fracture at 3 h post-trauma (hpt). Next, PT rats received either RU.521 (12 mg/kg in povidone; n = 8) or vehicle (povidone only; n = 5) immediately after injury and were followed up for 5 weeks post-trauma to assess bone regeneration by radiography and histology.
Results:
IFNβ levels were significantly decreased only at 24 h in BALF of RU.521 treated mice. At 3hpt mtDNA was significantly elevated in PT rats compared to rats without injury. When treated with RU.521, PT rats showed improvement in bone healing compared to vehicle control PT rats.
Conclusions:
These data reveal that the cGAS-STING signaling pathway influences trauma-induced delayed bone healing. However, further evaluation of this pathway at the cellular and molecular levels to augment PT associated detrimental effects is needed.
Insights
The cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes (cGAS-STING) pathway impacts delayed bone healing after severe trauma. Inhibiting this pathway with RU.521 improved fracture repair in a polytrauma rat model.
Area of Science:
- Immunology
- Biomedical Engineering
- Molecular Biology
Background:
- The cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes (cGAS-STING) pathway is crucial for immune responses in autoimmune diseases and cancer.
- Its role in fracture healing following severe trauma remains largely unexplored.
Purpose of the Study:
- To investigate the involvement of the cGAS-STING signaling pathway in delayed bone healing associated with polytrauma (PT) fractures.
- To determine if inhibiting the cGAS-STING pathway can enhance fracture healing in a PT model.
Main Methods:
- Preliminary dosage determination of the cGAS inhibitor RU.521 in mice.
- Quantification of plasma mitochondrial DNA (mtDNA) in a clinically relevant PT rat model (burn, blunt trauma, femoral fracture).
- Assessment of bone regeneration via radiography and histology in PT rats treated with RU.521 or vehicle.
Main Results:
- Elevated plasma mtDNA levels were observed in PT rats at 3 hours post-trauma.
- Treatment with RU.521 significantly improved bone healing in PT rats compared to vehicle controls.
- IFNβ levels were decreased in the BALF of RU.521 treated mice at 24 hours.
Conclusions:
- The cGAS-STING signaling pathway plays a significant role in trauma-induced delayed bone healing.
- Further research is needed to elucidate the cellular and molecular mechanisms for augmenting PT-associated healing deficits.
