Sera from severe trauma patients with pneumonia and without infectious complications have differential effects on neutrophil biology

Blunt Cerebrovascular Injury Complications in Aging Adults: A National Trauma Database Study

INTRODUCTION

Blunt cerebrovascular injury (BCVI) is defined as a nonpenetrating injury to the carotid or vertebral arteries which can be highly morbid. Because BCVI is rare, most studies have been devoted to triaging trauma patients for BCVI identification, with little data available regarding the complications these patients experience after initial evaluation. Here, we analyze the association of complications during admission for BCVI patients.

METHODS

The National Trauma Databank was queried from 2007 to 2014 for adults ≥65 y old. Demographics, incidence of BCVI, and injury data were evaluated using univariate analysis. Rates of inpatient complications due to acutely acquired infections and strokes were evaluated using univariate and multivariable analysis.

RESULTS

We identified 666,815 non-BCVI and 552 BCVI patients. Patients with a BCVI were typically male, White, younger (65-75-y-old), had three or more comorbidities, and had Medicare insurance. BCVI patients had a mild head injury upon arrival at the emergency department and experienced a motor vehicle accident/fall. The median length of stay in the intensive care unit, days spent on a ventilator, and presence of polytrauma were higher among BCVI patients. BCVI patients had increased odds of experiencing a stroke and pneumonia as complications while admitted compared to their non-BCVI counterparts.

CONCLUSIONS

Postinjury, patients who suffered a BCVI had higher odds of stroke and pneumonia than patients who did not experience a BCVI. Additional studies are needed to determine the modifiable risk factors associated with BCVIs among aging adults.

Quantitative Evaluation of Embolic Load in Femoral and Tibial Shaft Fractures Treated With Reamed Intramedullary Fixation

OBJECTIVES

To compare the volume of embolic load during intramedullary fixation of femoral and tibial shaft fractures. Our hypothesis was that tibial intramedullary nails (IMNs) would be associated with less volume of intravasation of marrow than IM nailing of femur fractures.

DESIGN

Prospective observational study.

SETTING

Urban Level I trauma center.

PATIENTS/PARTICIPANTS

Twenty-three patients consented for the study: 14 with femoral shaft fractures and 9 with tibial shaft fractures.

INTERVENTION

All patients underwent continuous transesophageal echocardiography, and volume of embolic load was evaluated during 5 distinct stages: postinduction, initial guide wire, reaming (REAM), nail insertion, and postoperative.

MAIN OUTCOME MEASUREMENTS

Volume of embolic load was measured based on previously described luminosity scores. The embolic load based on fracture location and procedure stage was evaluated using a mixed effects model.

RESULTS

The IMN procedure increased the embolic load by 215% (-12% to 442%, P = 0.07) in femur patients relative to tibia patients after adjusting for baseline levels. Of the 5 steps measured, REAM was associated with the greatest increase in embolic load relative to the guide wire placement and controlling for fracture location (421%, 95% confidence interval: 169%-673%, P < 0.01).

CONCLUSIONS

Femoral shaft IMN fixation was associated with a 215% increase in embolic load in comparison with tibial shaft IMN fixation, with the greatest quantitative load during the REAM stage; however, both procedures produce embolic load.

LEVEL OF EVIDENCE

Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Ethyl Pyruvate Reduces Systemic Leukocyte Activation via Caspase-1 and NF-κB After Blunt Chest Trauma and Haemorrhagic Shock

Background: Blunt chest (thoracic) trauma (TxT) and haemorrhagic shock with subsequent resuscitation (H/R) induce strong systemic and local inflammatory response, which is closely associated with apoptotic cell loss and subsequently impaired organ function. The underlying mechanisms are not completely understood, therefore, the treatment of patients suffering from TxT+H/R is challenging. In our recent studies, we have demonstrated local anti-inflammatory effects of ethyl pyruvate (EtP) in lung and liver after TxT+H/R. Here, the therapeutic potential of a reperfusion regime with EtP on the early post-traumatic systemic inflammatory response and apoptotic changes after TxT followed by H/R were investigated.

Methods: Female Lewis rats underwent TxT followed by haemorrhagic shock (60 min). Resuscitation was performed with own blood transfusion and either lactated Ringers solution (LR) or LR supplemented with EtP (50 mg/kg). Sham group underwent the surgical procedures. After 2 h blood as well as lung and liver tissues were obtained for analyses. Systemic activation of neutrophils (expression of CD11b and CD62L), leukocyte phagocytosis, apoptosis (caspase-3/7 activation), pyroptosis (caspase-1 activation) and NF-κB p65 activity were assessed. p < 0.05 was considered significant.

Results: TxT+H/R-induced systemic activation of neutrophils (increased CD11b and reduced CD62L expression) was significantly reduced by EtP. Trauma-induced delayed neutrophil apoptosis was further reduced by EtP reperfusion but remained unaltered in monocytes. Reperfusion with EtP significantly increased the phagocytizing capacity of granulocytes. Trauma-induced inflammasome activation, which was observed in monocytes and not in neutrophils, was significantly reduced by EtP in both cell entities. NF-κB p65 activation, which was increased in neutrophils and monocytes was significantly decreased in monocytes.

Conclusion: TxT+H/R-induced systemic activation of both neutrophils and monocytes concomitant with increased systemic inflammation was reduced by a reperfusion with EtP and was associated with a down-regulation of NF-κB p65 activation.

Altered cell surface receptor dynamics and circulatory occurrence of neutrophils in a small animal fracture model

INTRODUCTION

Excessive activation of the immune response after femoral fractures and fracture fixation is potentially associated with the development of systemic and local complications, particularly in multiple trauma patients. A dysregulated function of neutrophils, the most prevailing immune cells in circulation, has been discussed as a central pathophysiological background for these unfavourable post-traumatic courses. Our aim was to investigate alterations in activity and functionality as expressed by the cell surface receptor dynamics of circulatory neutrophils after femoral fracture and intramedullary stabilization.

MATERIAL AND METHODS

After intramedullary stabilization, an isolated femur fracture was induced in 18 Sprague-Dawley rats. Animals were terminated at different time points, i.e. after 3 (n = 5, group 3d), 7 (n = 5, group 7d) and 14 (n = 5, Group 14d) days and grouped accordingly. Additionally, baseline measurements were performed in one control animal per study group (n = 3) after anaesthesia induction and termination, without prior intramedullary nailing and fracture induction. The numbers and cell surface expression of CD11b, CD11a, CD62 L, and CD49d of circulating neutrophils were compared between groups.

RESULTS

Neutrophil numbers were significantly reduced at 3 days compared with baseline measurements (1.2 × 10⁵ vs. 6.3 × 10⁵ cells/mL, p < 0.01). By day 7, neutrophil counts significantly increased back to homeostatic levels (p < 0.05). At day 3, CD11b-expression was significantly reduced, whereas CD11a-expression was increased compared with the baseline measurements (p < 0.05). At day 7, the circulatory neutrophil pool exhibited a unique CD11b^high/CD11a^high-neutrophil subset showing a significantly increased co-expression of CD49d. The expression of CD62 L did not change significantly throughout the experiment compared with baseline measurements.

CONCLUSIONS

This descriptive small animal fracture study is the first to show that an intramedullary stabilized femur fracture is associated with a temporary reduction in circulatory neutrophil count and concurrent changes in circulatory neutrophil function. Moreover, we demonstrated that the restoration to homeostatic neutrophil activation status occurs concomitantly with the appearance of a novel neutrophil subtype (CD11b^high/CD11a^high) in circulation. Our fundamental new findings of the changes in circulatory neutrophil count and functionality after trauma form an excellent basis for future studies to further elucidate the role of neutrophils as activators and regulators of different post-traumatic processes, potentially resulting in local (e.g., fracture healing disturbances) or systemic (e.g., MODS) complications. This might result in the development of specific therapies to reduce adverse outcomes after trauma.

The impact of intramedullary nailing on the characteristics of the pulmonary neutrophil pool in rodents

PURPOSE

Dysregulation of polymorphonuclear neutrophil (PMN) biology is associated with the development of inflammatory complications after trauma, such as acute respiratory distress syndrome (ARDS). It has been demonstrated that intramedullary nailing is both associated with altered pulmonary neutrophil deposition and the occurrence of ARDS. This standardized study aimed to characterize the long-term remote neutrophil response in the lungs in case of a femur fracture and intramedullary nailing.

METHODS

A standardized rat model including intramedullary nailing and a femur fracture was utilized. Groups were terminated after observation times of three, seven and 14 days. Neutrophils were isolated from lung parenchyma and broncho-alveolar lavage fluid (BALF) and analyzed by flow cytometry. Absolute neutrophil numbers as well as membrane expression levels of CD11b, CD62L, and CD11a were compared.

RESULTS

Pulmonary neutrophil numbers were increased 3 days after intervention. Membrane expression levels of CD11b (P < 0.01), CD62L (P < 0.01), and CD11a (P = 0.06) on parenchymal PMNs increased as well after 3 days. Thereafter, values restored gradually to physiological levels. Furthermore, neutrophil activation status patterns between parenchymal and BALF neutrophil pools did not correlate.

CONCLUSIONS

The current study demonstrates that IMN and a femur fracture are associated with transient increased pulmonary PMN deposition, as well as a specific pattern of activation characterized by temporary increased selectin and integrin receptor expression on pulmonary neutrophils. This phenomenon might play an important role in the pathomechanism of ARDS after IMN. Moreover, we found striking differences between parenchymal and BALF-neutrophil populations, demonstrating the limited readout potential of BALF analysis to investigate the entire pulmonary neutrophil pool.

Club cell protein 16 in sera from trauma patients modulates neutrophil migration and functionality via CXCR1 and CXCR2

Background

Club Cell protein (CC)16 correlates with lung injury and respiratory complications, which are in part triggered by polymorphonuclear leukocytes (PMNL) in severely traumatized patients (TP). CC16 exerts anti-inflammatory and immunosuppressive effects, however, its influence on PMNL functions after trauma is unknown. Here, we evaluated whether CC16 present in sera from TP could modify the biological functions of PMNL.

Methods

Sera from 16 severely injured TP without pneumonia (no P, n = 8) or with pneumonia (P, n = 8) were collected at admission to emergency department (ED) and 1 day prior pneumonia and pre-incubated with or without anti-CC16 antibody for CC16 neutralization. Samples from the equal post-injury days in the corresponding no P group were used. Neutrophils were isolated from healthy volunteers (HV, n = 5) and incubated with 20% of the serum medium from TP, respectively. In PMNL, CD62L, CD11b/CD18 and CD31 expression, migratory capacity, phagocytosis rate, oxidative burst and apoptosis were investigated. In isolated PMNL, CXCR1 and CXCR2 were neutralized before stimulation with CC16, and oxidative burst, phagocytosis and apoptosis were analyzed in neutrophils and their subsets.

Results

Serum from the P group enhanced significantly PMNL migration compared to no P group, while CC16-neutralization further increased the migratory rate of PMNL in both groups. CC16-neutralization increased significantly the expression of CD62L in the P group at ED. Oxidative burst was significantly increased in the P group vs. no P during the study period. CC16 seemed to have no influence on oxidative burst and phagocytosis in TP. However, in a more controlled study design, CC16 induced a significant increase of oxidative burst and a decrease of apoptosis of CD16⁺ granulocytes. These effects were markedly observed in mature CD16^brightCD62L^bright and immune suppressive CD16^brightCD62L^dim neutrophils. In mature subset, CXCR1 and CXCR2 neutralization diminished CC16-induced effects.

Conclusions

CC16 in sera from multiply traumatized patients, notably of those with pneumonia, has significant effects on PMNL. The results suggest an association of CC16 with CXCR1 and CXCR2. Our data suggest that CC16 reduces the migratory capacity of PMNL and thus modulates their function in patients with respiratory complications after trauma.