Dataset Information

Fracture healing in a polytrauma rat model is influenced by mtDNA:cGAS complex mediated pro-inflammation.

ABSTRACT:

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.

SUBMITTER: Muire PJ

PROVIDER: S-EPMC10473996 | biostudies-literature | 2023 Sep

REPOSITORIES: biostudies-literature

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Publications

Fracture healing in a polytrauma rat model is influenced by mtDNA:cGAS complex mediated pro-inflammation.

Muire Preeti J PJ Lofgren Alicia L AL Shiels Stefanie M SM Wenke Joseph C JC

Journal of experimental orthopaedics 20230901 1

<h4>Purpose</h4>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.<h4>Methods</h4>For preliminary anal ...[more]

PMID: 37656236

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Project description:BackgroundSingular traumatic insults, such as bone fracture, typically initiate an appropriate immune response necessary to restore the host to pre-insult homeostasis with limited damage to self. However, multiple concurrent insults, such as a combination of fracture, blunt force trauma, and burns (polytrauma), are clinically perceived to result in abnormal immune response leading to inadequate healing and resolution. To investigate this phenomenon, we created a model rat model of polytrauma.MethodsTo investigate relationship between polytrauma and delayed healing, we created a novel model of polytrauma in a rat which encompassed a 3-mm osteotomy, blunt chest trauma, and full-thickness scald burn. Healing outcomes were determined at 5 weeks where the degree of bone formation at the osteotomy site of polytrauma animals was compared to osteotomy only animals (OST).ResultsWe observed significant differences in the bone volume fraction between polytrauma and OST animals indicating that polytrauma negatively effects wound healing. Polytrauma animals also displayed a significant decrease in their ability to return to pre-injury weight compared to osteotomy animals. Polytrauma animals also exhibited significantly altered gene expression in osteogenic pathways as well as the innate and adaptive immune response. Perturbed inflammation was observed in the polytrauma group compared to the osteotomy group as evidenced by significantly altered white blood cell (WBC) profiles and significantly elevated plasma high-mobility group box 1 protein (HMGB1) at 6 and 24 h post-trauma. Conversely, polytrauma animals exhibited significantly lower concentrations of plasma TNF-alpha (TNF-α) and interleukin 6 (IL-6) at 72 h post-injury compared to OST.ConclusionsFollowing polytrauma with burn injury, the local and systemic immune response is divergent from the immune response following a less severe singular injury (osteotomy). This altered immune response that follows was associated with a reduced capacity for wound healing.

Project description:ObjectivesThe aim of this study was to examine the effects of cephalexin on the fracture union histomorphometrically, radiologically, biomechanically, immunohistochemically, and histopathologically in a rat femur fracture model and to evaluate the effects of the antibiotics to be used in the prophylaxis of fracture infection on the union of the fracture.Materials and methodsA total of 48 male Wistar rats were divided into four groups as two-week control (C2) and cephalexin (CEP2) and four-week control (C4) and cephalexin (CEP4). After establishment of standard fracture model on right femurs, 60 mg/kg/day of cephalexin was applied to CEP2 and CEP4 by oral gavage. Radiological, biomechanical, histopathological, immunohistochemical, and histomorphometric examinations were performed on amputated femurs.ResultsCallus volume of CEP4 group significantly increased compared to CEP2 group (p=0.005), while no significant difference was found in the bone mineral density and callus/bone volume among the groups (p>0.05). There was no significant difference in flexural strength between the C4 and CEP4 groups (p=0.093). Histological healing scores increased from Week 2 to Week 4 (p=0.002) and inflammation scores decreased in both control and cephalexin groups (p=0.010 and p=0.008); however, no significant difference was found in healing and inflammation scores (p>0.05). The CD34+ immunoreactivity in the CEP2 group was significantly higher than the C2 group (p=0.029). Collagen type III level was significantly lower in the CEP2 and CEP4 groups compared to the corresponding control groups (p=0.008 and p=0.016, respectively).ConclusionCephalexin did not exert any radiological, histopathological, histomorphometric, biomechanical, and immunohistochemical adverse effects on the femoral fracture healing model in rats; however, it showed positive effects on CD34 and Collagen type III levels. Based on these findings, antibiotherapy with cephalexin may be considered as a safe treatment for fracture union.

Dataset Information

Fracture healing in a polytrauma rat model is influenced by mtDNA:cGAS complex mediated pro-inflammation.

Purpose

Methods

Results

Conclusions

Publications

Fracture healing in a polytrauma rat model is influenced by mtDNA:cGAS complex mediated pro-inflammation.

Similar Datasets

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