Pulmonary Arterial Thrombosis in a Murine Model of Blunt Thoracic Trauma

Experimental study of a novel mouse model of tibial shaft fracture combined with blunt chest trauma

BACKGROUD

Thoracic Trauma and Limb Fractures Are the Two most Common Injuries in Multiple Trauma. However, there Is Still a Lack of Mouse Models of Trauma Combining Tibial Shaft Fracture (TSF) and Thoracic Trauma. In this Study, we Attempted to Develop a Novel Mouse Model of TSF Combined with Blunt Chest Trauma (BCT).

METHODS

A total of 84 C57BL/6J male mice were used as the multiple trauma model. BCT was induced by hitting the chests of mice with heavy objects, and TSF was induced by hitting the tibia of mice with heavy objects after intramedullary fixation. Serum specimens of mice were received by cardiac puncture at defined time points of 0, 6, 12, 24, 48, and 72 h.

RESULTS

Body weight and body temperature tended to decrease within 24 h after multiple trauma. Hemoglobin analyses revealed a decrease during the first 24 h after multiple trauma. Some animals died by cardiac puncture immediately after chest trauma. These animals exhibited the most severe pulmonary contusion and hemorrhage. The level of lung damage varied in diverse mice but was apparent in all animals. Classic hematoxylin and eosin (H&E)-stained paraffin pulmonary sections of mice with multiple trauma displayed hemorrhage and an immunoinflammatory reaction. Bronchoalveolar lavage fluid (BALF) and serum samples of mice with multiple trauma showed an upregulation of interleukin-1β (IL-1β), IL-6, and tumor necrosis factor-1α (TNF-1α) compared with the control group. Microimaging confirmed the presence of a tibia fracture and pulmonary contusion.

CONCLUSIONS

The novel mouse multiple trauma model established in this study is a common trauma model that shows similar pathological mechanisms and imaging characteristics in patients with multiple injuries. This study is useful for determining whether blockade or intervention of the cytokine response is beneficial for the treatment of patients with multiple trauma. Further research is needed in the future.

Lung contusion complicated by pneumonia worsens lung injury via the inflammatory effect of alveolar small extracellular vesicles on macrophages and epithelial cells

BACKGROUND

Lung contusion (LC) complicated by pneumonia is associated with a higher risk of acute lung injury (ALI) mediated by activation of immune cells and injury to the lung epithelium. Small extracellular vesicles (sEVs) are essential mediators of cellular crosstalk; however, their role in the development of postinjury ALI remains unclear. We hypothesized that LC complicated by pneumonia increases the pro-inflammatory effect of alveolar sEVs on macrophages and the cytotoxicity of alveolar sEVs to pulmonary epithelial cells, worsening the severity of ALI.

METHODS

Studies in C57BL/6 mice were designed with four groups: sham, LC, Pneumonia (Pneu), and LC + Pneu. Lung contusion was induced by a cortical controlled impactor, while pneumonia was conducted by intratracheal injection of 10 5 cfu Pseudomonas aeruginosa . Bronchoalveolar lavage fluid (BAL) was harvested 24 hours postinfection, and sEVs were purified by centrifugation and size exclusion chromatography. To evaluate the effect of alveolar sEV on cells, sEVs from each group were cocultured with macrophages (RAW 264.7) to assess cytokine release and lung epithelial cells (MLE 12) to assess epithelial cytotoxicity.

RESULTS

The LC + Pneu group severely injured lungs histologically and increased the susceptibility to the bacteria. The LC + Pneu group showed higher concentrations of proteins, macrophage inflammatory protein 1-alpha (MIP1α), and intercellular adhesion molecule 1 (ICAM-1) in BAL. MIP1α and ICAM-1 expression in the macrophages increased after incubation with sEVs from the LC + Pneu group. Moreover, the sEVs demonstrated higher cytotoxicity to epithelial cells and increased apoptosis in epithelial cells after incubation with sEVs from the LC + Pneu group.

CONCLUSION

Lung contusion complicated by pneumonia increased the pro-inflammatory effect of alveolar sEVs on macrophages and the cytotoxicity of alveolar sEVs to pulmonary epithelial cells, worsening the severity of ALI. These results demonstrate the potential importance of alveolar sEVs in lung inflammation following a bacterial infection after trauma.

Venous thromboembolic events associated with blood product administration in an era of whole blood use

BACKGROUND

The risks associated with blood product administration and venous thromboembolic events remains unclear. We sought to determine which blood products were associated with the development of deep vein thrombosis (DVT) and pulmonary embolism (PE).

METHODS

We analyzed data from patients ≥18 years of age in the Trauma Quality Improvement Program (TQIP) database that received ≥1 blood product and survived ≥24 ​h.

RESULTS

There were 42,399 that met inclusion, of whom, 2086 had at least one VTE event. In our multivariable logistic regression model, we found that WB had a unit odds ratio (uOR) of 1.05 (95 ​% CI 1.02-1.08) for DVT and 1.08 (1.05-1.12) for PE. Compared to WB, platelets had a higher uOR for DVT of 1.09 (1.04-1.13) but similar uOR for PE of 1.08 (1.03-1.14).

CONCLUSIONS

We found an association of both DVT and PE with early whole blood and platelets.

Pulmonary artery in situ thrombosis due to patent ductus arteriosus: a case report

Background

Pulmonary Artery in situ Thrombosis (PAIST) refers to a thrombus forming within the pulmonary arterial system, distinct from an embolus originating from elsewhere in the body (e.g., the deep veins of the lower extremities) and traveling to the lungs where it lodges and forms.

Case presentation

We present a case of PAIST caused by the arterial ductus arteriosus. The patient primarily presented with dyspnea, and the chest pain dichotomy Computed Tomography Angiography(CTA) suggested that a nodular low-density filling defect was seen in the lumen of the left pulmonary artery trunk. Initially, pulmonary embolism (PE) was suspected. However, upon reevaluation of the imaging, it became apparent that the patient's pulmonary artery obstruction was closely associated with the ductus arteriosus. After admission, the patient was treated with sodium ampicillin (2.0 g Q12H) for infection, heparin sodium (5,000 IU Q12H) for anticoagulation, and metoprolol succinate extended-release tablets (23.75 mg QD) to correct cardiac remodeling, among other treatments. Subsequently, the patient underwent a cardiac surgery involving the ligation of the arterial duct, resection of pulmonary artery lesions, and open-heart surgery with extracorporeal circulation support. Postoperative examination of the pulmonary artery mass indicated coagulation tissue. The final diagnosis was "PAIST".

Conclusion

Both PAIST and PE manifest as low-density filling defects in the pulmonary arteries. However, due to the relative unfamiliarity with PAIST, such findings are often initially attributed to PE.

Role of Interventional Radiology in the Management of Non-aortic Thoracic Trauma

Trauma remains a leading cause of death for all age groups, and nearly two-thirds of these individuals suffer thoracic trauma. Due to the various types of injuries, including vascular and nonvascular, interventional radiology plays a major role in the acute and chronic management of the thoracic trauma patient. Interventional radiologists are critical members in the multidisciplinary team focusing on treatment of the patient with thoracic injury. Through case presentations, this article will review the role of interventional radiology in the management of trauma patients suffering thoracic injuries.

In situ Pulmonary Artery Thrombosis: A Previously Overlooked Disease

Pulmonary thromboembolism (PTE) is the third leading cause of death in cardiovascular diseases. PTE is believed to be caused by thrombi detached from deep veins of lower extremities. The thrombi travel with systemic circulation to the lung and block pulmonary arteries, leading to sudden disruption of hemodynamics and blood gas exchange. However, this concept has recently been challenged by accumulating evidence demonstrating that de novo thrombosis may be formed in pulmonary arteries without deep venous thrombosis. On the other hand, chronic thromboembolic pulmonary hypertension (CTEPH), a subtype of pulmonary hypertension, could have different pathogenesis than traditional PTE. Therefore, this article summarized and compared the risk factors, the common and specific pathogenic mechanisms underlying PTE, in situ pulmonary artery thrombosis, and CTEPH at molecular and cellular levels, and suggested the therapeutic strategies to these diseases, aiming to facilitate understanding of pathogenesis, differential diagnosis, and precision therapeutics of the three pulmonary artery thrombotic diseases.

P-selectin antibody treatment after blunt thoracic trauma prevents early pulmonary arterial thrombosis without changes in viscoelastic measurements of coagulation

INTRODUCTION

Previously, in a murine model of blunt thoracic trauma, we provided evidence of primary pulmonary thrombosis associated with increased expression of the cell adhesion molecule, P-selectin. In this study, mice are treated with P-selectin blocking antibody after injury to investigate the clinical viability of this antibody for the prevention of pulmonary thrombosis. In addition, viscoelastic testing is performed to investigate if P-selectin inhibition has a detrimental impact on normal hemostasis.

METHODS

A murine model of thoracic trauma was used. Mice were divided into sham control and experimental injury groups. Thirty minutes after trauma, mice were treated with the following: P-selectin blocking antibody, isotype control antibody, low-dose heparin, high-dose heparin, or normal saline. At 90 minutes, whole blood was collected for characterization of coagulation by viscoelastic coagulation monitor (VCM Vet; Entegrion, Durham, NC). Mean clotting time, clot formation time, clot kinetics (α angle), and maximum clot firmness were compared between each treatment group.

RESULTS

Mice that received P-selectin antibody 30 minutes after blunt thoracic trauma had four- to fivefold less (p < 0.001) arterial fibrin accumulation than those that received the isotype control. In both sham and trauma groups, compared with vehicle (normal saline) alone, no statistical difference was noted in any coagulation parameters after injection with P-selectin antibody, isotype control, or low-dose heparin. In addition, blinded histopathological evaluation yielded no difference in hemorrhage scores between injured mice treated with P-selectin blocking antibody and those treated with isotype antibody control.

CONCLUSION

This study supports the clinical use of P-selectin blocking antibody for the prevention of pulmonary thrombosis by confirming its efficacy when given after a blunt thoracic trauma. In addition, we demonstrated that the administration of P-selectin antibody does not adversely affect systemic coagulation as measured by viscoelastic testing, suggesting that P-selectin antibody can be safely given during the acute posttraumatic period.