Inflammatory and apoptotic alterations in serum and injured tissue after experimental polytrauma in mice: Distinct early response compared with single trauma or “double-hit” injury

Animal Models of Traumatic Brain Injury and Their Relevance in Clinical Settings

BACKGROUND

Traumatic brain injury (TBI) is a significant concern that often goes overlooked, resulting from various factors such as traffic accidents, violence, military services, and medical conditions. It is a major health issue affecting people of all age groups across the world, causing significant morbidity and mortality. TBI is a highly intricate disease process that causes both structural damage and functional deficits. These effects result from a combination of primary and secondary injury mechanisms. It is responsible for causing a range of negative effects, such as impairments in cognitive function, changes in social and behavioural patterns, difficulties with motor skills, feelings of anxiety, and symptoms of depression.

METHODS

TBI associated various animal models were reviewed in databases including PubMed, Web of Science, and Google scholar etc. The current study provides a comprehensive overview of commonly utilized animal models for TBI and examines their potential usefulness in a clinical context.

RESULTS

Despite the notable advancements in TBI outcomes over the past two decades, there remain challenges in evaluating, treating, and addressing the long-term effects and prevention of this condition. Utilizing experimental animal models is crucial for gaining insight into the development and progression of TBI, as it allows us to examine the biochemical impacts of TBI on brain mechanisms.

CONCLUSION

This exploration can assist scientists in unraveling the intricate mechanisms involved in TBI and ultimately contribute to the advancement of successful treatments and interventions aimed at enhancing outcomes for TBI patients.

Polytrauma impairs fracture healing accompanied by increased persistence of innate inflammatory stimuli and reduced adaptive response

The field of bone regeneration has primarily focused on investigating fracture healing and nonunion in isolated musculoskeletal injuries. Compared to isolated fractures, which frequently heal well, fractures in patients with multiple bodily injuries (polytrauma) may exhibit impaired healing. While some papers have reported the overall cytokine response to polytrauma conditions, significant gaps in our understanding remain in how fractures heal differently in polytrauma patients. We aimed to characterize fracture healing and the temporal local and systemic immune responses to polytrauma in a murine model of polytrauma composed of a femur fracture combined with isolated chest trauma. We collected serum, bone marrow from the uninjured limb, femur fracture tissue, and lung tissue over 3 weeks to study the local and systemic immune responses and cytokine expression after injury. Immune cell distribution was assessed by flow cytometry. Fracture healing was characterized using microcomputed tomography (microCT), histological staining, immunohistochemistry, mechanical testing, and small angle X-ray scattering. We detected more innate immune cells in the polytrauma group, both locally at the fracture site and systemically, compared to other groups. The percentage of B and T cells was dramatically reduced in the polytrauma group 6 h after injury and remained low throughout the study duration. Fracture healing in the polytrauma group was impaired, evidenced by the formation of a poorly mineralized and dysregulated fracture callus. Our data confirm the early, dysregulated inflammatory state in polytrauma that correlates with disorganized and impaired fracture healing.

LINE-1 RNA triggers matrix formation in bone cells via a PKR-mediated inflammatory response

Transposable elements (TEs) are mobile genetic modules of viral derivation that have been co-opted to become modulators of mammalian gene expression. TEs are a major source of endogenous dsRNAs, signaling molecules able to coordinate inflammatory responses in various physiological processes. Here, we provide evidence for a positive involvement of TEs in inflammation-driven bone repair and mineralization. In newly fractured mice bone, we observed an early transient upregulation of repeats occurring concurrently with the initiation of the inflammatory stage. In human bone biopsies, analysis revealed a significant correlation between repeats expression, mechanical stress and bone mineral density. We investigated a potential link between LINE-1 (L1) expression and bone mineralization by delivering a synthetic L1 RNA to osteoporotic patient-derived mesenchymal stem cells and observed a dsRNA-triggered protein kinase (PKR)-mediated stress response that led to strongly increased mineralization. This response was associated with a strong and transient inflammation, accompanied by a global translation attenuation induced by eIF2α phosphorylation. We demonstrated that L1 transfection reshaped the secretory profile of osteoblasts, triggering a paracrine activity that stimulated the mineralization of recipient cells.

A rat model of multicompartmental traumatic injury and hemorrhagic shock induces bone marrow dysfunction and profound anemia

BACKGROUND

Severe trauma is associated with systemic inflammation and organ dysfunction. Preclinical rodent trauma models are the mainstay of postinjury research but have been criticized for not fully replicating severe human trauma. The aim of this study was to create a rat model of multicompartmental injury which recreates profound traumatic injury.

METHODS

Male Sprague-Dawley rats were subjected to unilateral lung contusion and hemorrhagic shock (LCHS), multicompartmental polytrauma (PT) (unilateral lung contusion, hemorrhagic shock, cecectomy, bifemoral pseudofracture), or naïve controls. Weight, plasma toll-like receptor 4 (TLR4), hemoglobin, spleen to body weight ratio, bone marrow (BM) erythroid progenitor (CFU-GEMM, BFU-E, and CFU-E) growth, plasma granulocyte colony-stimulating factor (G-CSF) and right lung histologic injury were assessed on day 7, with significance defined as p values <0.05 (*).

RESULTS

Polytrauma resulted in markedly more profound inhibition of weight gain compared to LCHS (p = 0.0002) along with elevated plasma TLR4 (p < 0.0001), lower hemoglobin (p < 0.0001), and enlarged spleen to body weight ratios (p = 0.004). Both LCHS and PT demonstrated suppression of CFU-E and BFU-E growth compared to naïve (p < 0.03, p < 0.01). Plasma G-CSF was elevated in PT compared to both naïve and LCHS (p < 0.0001, p = 0.02). LCHS and PT demonstrated significant histologic right lung injury with poor alveolar wall integrity and interstitial edema.

CONCLUSIONS

Multicompartmental injury as described here establishes a reproducible model of multicompartmental injury with worsened anemia, splenic tissue enlargement, weight loss, and increased inflammatory activity compared to a less severe model. This may serve as a more effective model to recreate profound traumatic injury to replicate the human inflammatory response postinjury.

Multifunctional tannic acid-based nanocomposite methacrylated silk fibroin hydrogel with the ability to scavenge reactive oxygen species and reduce inflammation for bone regeneration

The microenvironment of bone defect site is vital for bone regeneration. Severe bone defect is often accompanied with severe inflammation and elevated generation of reactive oxygen species (ROS) during bone repair. In recent years, the unfriendly local microenvironment has been paid more and more attention. Some bioactive materials with the ability to regulate the microenvironment to promote bone regeneration urgently need to be developed. Here, we develop a multifunctional composite hydrogel composed of photo-responsive methacrylate silk fibroin (SFMA), laponite (LAP) nanocomposite and tannic acid (TA), aiming to endow hydrogel with antioxidant, anti-inflammatory and osteogenic induction ability. Characterization results confirmed that the SFMA-LAP@TA hydrogel could significantly improve the mechanical properties of hydrogel. The ROS-Scavenging ability of the hydrogel enabled bone marrow mesenchymal stem cells (BMSCs) to survive against H2O2-induced oxidative stress. In addition, the SFMA-LAP@TA hydrogel effectively decreased the expression of pro-inflammatory factors in RAW264.7. More importantly, the SFMA-LAP@TA hydrogel could enhance the expression of osteogenic markers of BMSCs under inflammatory condition and greatly promote new bone formation in a critical-sized cranial defect model. Above all, the multifunctional hydrogel could effectively promote bone regeneration in vitro and in vivo by scavenging ROS and reducing inflammation, providing a prospective strategy for bone regeneration.

Trauma-associated extracellular histones mediate inflammation via a MYD88-IRAK1-ERK signaling axis and induce lytic cell death in human adipocytes

Despite advances in the treatment and care of severe physical injuries, trauma remains one of the main reasons for disability-adjusted life years worldwide. Trauma patients often suffer from disturbances in energy utilization and metabolic dysfunction, including hyperglycemia and increased insulin resistance. White adipose tissue plays an essential role in the regulation of energy homeostasis and is frequently implicated in traumatic injury due to its ubiquitous body distribution but remains poorly studied. Initial triggers of the trauma response are mainly damage-associated molecular patterns (DAMPs) such as histones. We hypothesized that DAMP-induced adipose tissue inflammation contributes to metabolic dysfunction in trauma patients. Therefore, we investigated whether histone release during traumatic injury affects adipose tissue. Making use of a murine polytrauma model with hemorrhagic shock, we found increased serum levels of histones accompanied by an inflammatory response in white adipose tissue. In vitro, extracellular histones induced an inflammatory response in human adipocytes. On the molecular level, this inflammatory response was mediated via a MYD88-IRAK1-ERK signaling axis as demonstrated by pharmacological and genetic inhibition. Histones also induced lytic cell death executed independently of caspases and RIPK1 activity. Importantly, we detected increased histone levels in the bloodstream of patients after polytrauma. Such patients might benefit from a therapy consisting of activated protein C and the FDA-approved ERK inhibitor trametinib, as this combination effectively prevented histone-mediated effects on both, inflammatory gene activation and cell death in adipocytes. Preventing adipose tissue inflammation and adipocyte death in patients with polytrauma could help minimize posttraumatic metabolic dysfunction.

Temporal and Spatial Patterns of Inflammation and Tissue Injury in Patients with Postoperative Respiratory Failure after Lung Resection Surgery: A Nested Case-Control Study

Thoracic surgeries involving resection of lung tissue pose a risk of severe postoperative pulmonary complications, including acute respiratory distress syndrome (ARDS) and respiratory failure. Lung resections require one-lung ventilation (OLV) and, thus, are at higher risk of ventilator-induced lung injury (VILI) attributable to barotrauma and volutrauma in the one ventilated lung, as well as hypoxemia and reperfusion injury on the operated lung. Further, we also aimed to assess the differences in localized and systemic markers of tissue injury/inflammation in those who developed respiratory failure after lung surgery versus matched controls who did not develop respiratory failure. We aimed to assess the different inflammatory/injury marker patterns induced in the operated and ventilated lung and how this compared to the systemic circulating inflammatory/injury marker pattern. A case-control study nested within a prospective cohort study was performed. Patients with postoperative respiratory failure after lung surgery (n = 5) were matched with control patients (n = 6) who did not develop postoperative respiratory failure. Biospecimens (arterial plasma, bronchoalveolar lavage separately from ventilated and operated lungs) were obtained from patients undergoing lung surgery at two timepoints: (1) just prior to initiation of OLV and (2) after lung resection was completed and OLV stopped. Multiplex electrochemiluminescent immunoassays were performed for these biospecimen. We quantified 50 protein biomarkers of inflammation and tissue injury and identified significant differences between those who did and did not develop postoperative respiratory failure. The three biospecimen types also display unique biomarker patterns.

Pulmonary inflammatory response and immunomodulation to multiple trauma and hemorrhagic shock in pigs

BACKGROUND

Patients suffering from severe trauma experience substantial immunological stress. Lung injury is a known risk factor for the development of posttraumatic complications, but information on the long-term course of the pulmonary inflammatory response and treatment with mild hypothermia are scarce.

AIM

To investigate the pulmonary inflammatory response to multiple trauma and hemorrhagic shock in a porcine model of combined trauma and to assess the immunomodulatory properties of mild hypothermia.

METHODS

Following induction of trauma (blunt chest trauma, liver laceration, tibia fracture), two degrees of hemorrhagic shock (45 and 50%) over 90 (n = 30) and 120 min. (n = 20) were induced. Animals were randomized to hypothermia (33°C) or normothermia (38°C). We evaluated bronchoalveolar lavage (BAL) fluid and tissue levels of cytokines and investigated changes in microRNA- and gene-expression as well as tissue apoptosis.

RESULTS

We observed a significant induction of Interleukin (IL) 1β, IL-6, IL-8, and Cyclooxygenase-2 mRNA in lung tissue. Likewise, an increased IL-6 protein concentration could be detected in BAL-fluid, with a slight decrease of IL-6 protein in animals treated with hypothermia. Lower IL-10 protein levels in normothermia and higher IL-10 protein concentrations in hypothermia accompanied this trend. Tissue apoptosis increased after trauma. However, intervention with hypothermia did not result in a meaningful reduction of pro-inflammatory biomarkers or tissue apoptosis.

CONCLUSION

We observed signs of a time-dependent pulmonary inflammation and apoptosis at the site of severe trauma, and to a lower extent in the trauma-distant lung. Intervention with mild hypothermia had no considerable effect during 48 hours following trauma.

Thoracic trauma promotes alpha-Synuclein oligomerization in murine Parkinson's disease

BACKGROUND

Systemic and neuroinflammatory processes play key roles in neurodegenerative diseases such as Parkinson's disease (PD). Physical trauma which induces considerable systemic inflammatory responses, represents an evident environmental factor in aging. However, little is known about the impact of physical trauma, on the immuno-pathophysiology of PD. Especially blunt chest trauma which is associated with a high morbidity and mortality rate in the elderly population, can induce a strong pulmonary and systemic inflammatory reaction. Hence, we sought out to combine a well-established thoracic trauma mouse model with a well-established PD mouse model to characterize the influence of physical trauma to neurodegenerative processes in PD.

METHODS

To study the influence of peripheral trauma in a PD mouse model we performed a highly standardized blunt thorax trauma in a well-established PD mouse model and determined the subsequent local and systemic response.

RESULTS

We could show that blunt chest trauma leads to a systemic inflammatory response which is quantifiable with increased inflammatory markers in bronchoalveolar fluids (BALF) and plasma regardless of the presence of a PD phenotype. A difference of the local inflammatory response in the brain between the PD group and non-PD group could be detected, as well as an increase in the formation of oligomeric pathological alpha-Synuclein (asyn) suggesting an interplay between peripheral thoracic trauma and asyn pathology in PD.

CONCLUSION

Taken together this study provides evidence that physical trauma is associated with increased asyn oligomerization in a PD mouse model underlining the relevance of PD pathogenesis under traumatic settings.

Substance P Serum Degradation in Complex Regional Pain Syndrome - Another Piece of the Puzzle?

In a previous study, we demonstrated that the serum peptidase system might be less efficient in complex regional pain syndrome (CRPS). Since the neuropeptide substanc P (SP) contributes to inflammation in CRPS, we now investigated the metabolism of SP in CRPS specifically. An SP metabolism assay was performed in 24 CRPS patients, which constitute a subgroup of our previous investigation on BK degradation. In addition, we included 26 healthy controls (24 newly recruited plus 2 from our previous investigation), and 13 patients after limb trauma, who did not fulfil the CRPS diagnostic criteria (trauma controls, TC) were included. We adapted a thin layer chromatography assay (TLC) to quantify SP disappearance after incubation with 7.5 µL of serum. These results were compared with bradykinin (BK) metabolization to BK1-8 and BK1-5 fragments from our previous study. In addition, TC were clinically and quantitative sensory testing (QST) phenotyped; the phenotyping of CRPS patients was retrieved from our existing database. SP metabolism was less efficient in CRPS and TC patient serum vs human control (HC) serum (P < .03) suggesting reduced activity of the neutral endopeptidase (NEP) and/or the angiotensin converting enzyme (ACE). Together with the decreased occurrence of BK1-5 fragment in CRPS and TC, this suggests a reduced activation of the angiotensin converting enzyme (ACE). There was no clear clinical phenotype related to impaired SP degradation; duration of disease and gender were also not associated. Most importantly, results in TC did not differ from CRPS. Collectively, our current and previous experimental results suggest that limb trauma reduces serum peptidase metabolism of SP ex vivo, specifically serum ACE activity. However, this finding is not CRPS-specific and seems to be rather a long-term consequence of the trauma itself. PERSPECTIVE: The experimental data from this study further support the hypothesis that impaired metabolism of inflammatory peptides potentially contribute to the development of posttraumatic pain in CRPS or limb trauma patients.

Influence of Concomitant Extracranial Injury on Functional and Cognitive Recovery From Mild Versus Moderateto Severe Traumatic Brain Injury

OBJECTIVE

To determine the effect of extracranial injury (ECI) on 6-month outcome in patients with mild traumatic brain injury (TBI) versus moderate-to-severe TBI.

PARTICIPANTS/SETTING

Patients with TBI (n = 135) or isolated orthopedic injury (n = 25) admitted to a UK major trauma center and healthy volunteers (n = 99).

DESIGN

Case-control observational study.

MAIN MEASURES

Primary outcomes: (a) Glasgow Outcome Scale Extended (GOSE), (b) depression, (c) quality of life (QOL), and (d) cognitive impairment including verbal fluency, episodic memory, short-term recognition memory, working memory, sustained attention, and attentional flexibility.

RESULTS

Outcome was influenced by both TBI severity and concomitant ECI. The influence of ECI was restricted to mild TBI; GOSE, QOL, and depression outcomes were significantly poorer following moderate-to-severe TBI than after isolated mild TBI (but not relative to mild TBI plus ECI). Cognitive impairment was driven solely by TBI severity. General health, bodily pain, semantic verbal fluency, spatial recognition memory, working memory span, and attentional flexibility were unaffected by TBI severity and additional ECI.

CONCLUSION

The presence of concomitant ECI ought to be considered alongside brain injury severity when characterizing the functional and neurocognitive effects of TBI, with each presenting challenges to recovery.

Resolution of inflammation in bone regeneration: From understandings to therapeutic applications

Impaired bone healing occurs in 5-10% of cases following injury, leading to a significant economic and clinical impact. While an inflammatory response upon injury is necessary to facilitate healing, its resolution is critical for bone tissue repair as elevated acute or chronic inflammation is associated with impaired healing in patients and animal models. This process is governed by important crosstalk between immune cells through mediators that contribute to resolution of inflammation in the local healing environment. Approaches modulating the initial inflammatory phase followed by its resolution leads to a pro-regenerative environment for bone regeneration. In this review, we discuss the role of inflammation in bone repair, the negative impact of dysregulated inflammation on bone tissue regeneration, and how timely resolution of inflammation is necessary to achieve normal healing. We will discuss applications of biomaterials to treat large bone defects with a specific focus on resolution of inflammation to modulate the immune environment following bone injury, and their observed functional benefits. We conclude the review by discussing future strategies that could lead to the realization of anti-inflammatory therapeutics for bone tissue repair.

Beyond the Brain: Peripheral Interactions after Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of death and disability, and there are currently no pharmacological treatments known to improve patient outcomes. Unquestionably, contributing toward a lack of effective treatments is the highly complex and heterogenous nature of TBI. In this review, we highlight the recent surge of research that has demonstrated various central interactions with the periphery as a potential major contributor toward this heterogeneity and, in particular, the breadth of research from Australia. We describe the growing evidence of how extracranial factors, such as polytrauma and infection, can significantly alter TBI neuropathology. In addition, we highlight how dysregulation of the autonomic nervous system and the systemic inflammatory response induced by TBI can have profound pathophysiological effects on peripheral organs, such as the heart, lung, gastrointestinal tract, liver, kidney, spleen, and bone. Collectively, this review firmly establishes TBI as a systemic condition. Further, the central and peripheral interactions that can occur after TBI must be further explored and accounted for in the ongoing search for effective treatments.

Reduced serum protease activity in Complex Regional Pain Syndrome: The impact of angiotensin-converting enzyme and carboxypeptidases

Complex Regional Pain Syndrome (CRPS) occurs in about 2% of patients after fracture of the limbs. In an earlier clinical study with 102 probands we have shown that the serum protease network in CRPS might be less effective. Based on these results we hypothesized that angiotensin-converting enzyme (ACE) and carboxypeptidase N (CPN) activity contribute to the differences of labeled bradykinin (DBK) degradation by patients' sera. Details of the enzymatic processes remained however unclear. The contributions of ACE and CPN in the serum degradation of DBK were studied using specific inhibitors. CPN1-ELISA was performed in serum. It was confirmed that the majority of DBK was degraded by ACE and CPN. The data delivered proof that the ACE serum activity was lowered in CRPS. High-resolution mass spectrometry was additionally used for protein expression analysis of sera of above study cohort (CRPS vs. healthy probands). According to principal component analysis of these data, significant differences between CRPS and control samples only occurred in sera of females younger than 46 years. In these CRPS patients, a number of defence / immunity-related proteins and members of the renin-angiotensin system (RAS) protein network were regulated. The impact of CPN in CRPS pathophysiology is subject to further investigation. The data support the hypothesis that both the RAS and the innate immune system might be affected in CRPS. A database of regulated serum proteins was established for future research.

Complement Factor C5a Inhibits Apoptosis of Neutrophils-A Mechanism in Polytrauma?

Life-threatening polytrauma results in early activation of the complement and apoptotic system, as well as leukocytes, ultimately leading to the clearance of damaged cells. However, little is known about interactions between the complement and apoptotic systems in PMN (polymorphonuclear neutrophils) after multiple injuries. PMN from polytrauma patients and healthy volunteers were obtained and assessed for apoptotic events along the post-traumatic time course. In vitro studies simulated complement activation by the exposure of PMN to C3a or C5a and addressed both the intrinsic and extrinsic apoptotic pathway. Specific blockade of the C5a-receptor 1 (C5aR1) on PMN was evaluated for efficacy to reverse complement-driven alterations. PMN from polytrauma patients exhibited significantly reduced apoptotic rates up to 10 days post trauma compared to healthy controls. Polytrauma-induced resistance was associated with significantly reduced Fas-ligand (FasL) and Fas-receptor (FasR) on PMN and in contrast, significantly enhanced FasL and FasR in serum. Simulation of systemic complement activation revealed for C5a, but not for C3a, a dose-dependent abrogation of PMN apoptosis in both intrinsic and extrinsic pathways. Furthermore, specific blockade of the C5aR1 reversed C5a-induced PMN resistance to apoptosis. The data suggest an important regulatory and putative mechanistic and therapeutic role of the C5a/C5aR1 interaction on PMN apoptosis after polytrauma.

Systemic T Cell Exhaustion Dynamics Is Linked to Early High Mobility Group Box Protein 1 (HMGB1) Driven Hyper-Inflammation in a Polytrauma Rat Model

We previously reported an early surge in high mobility group box protein 1 (HMGB1) levels in a polytrauma (PT) rat model. This study investigates the association of HMGB1 levels in mediating PT associated dysregulated immune responses and its influence on the cellular levels of receptor for advanced glycation end products (RAGE) and toll-like receptor 4 (TLR4). Using the same PT rat model treated with anti-HMGB1 polyclonal antibody, we evaluated changes in circulating inflammatory cytokines, monocytes/macrophages and T cells dynamics and cell surface expression of RAGE and TLR4 at 1, 3, and 7 days post-trauma (dpt) in blood and spleen. Notably, PT rats demonstrating T helper (Th)1 and Th2 cells type early hyper-inflammatory responses also exhibited increased monocyte/macrophage counts and diminished T cell counts in blood and spleen. In blood, expression of RAGE and TLR4 receptors was elevated on CD68+ monocyte/macrophages and severely diminished on CD4+ and CD8+ T cells. Neutralization of HMGB1 significantly decreased CD68+ monocyte/macrophage counts and increased CD4+ and CD8+ T cells, but not γδ+TCR T cells in circulation. Most importantly, RAGE and TLR4 expressions were restored on CD4+ and CD8+ T cells in treated PT rats. Overall, findings suggest that in PT, the HMGB1 surge is responsible for the onset of T cell exhaustion and dysfunction, leading to diminished RAGE and TLR4 surface expression, thereby possibly hindering the proper functioning of T cells.

Different experimental multiple trauma models induce comparable inflammation and organ injury

Multiple injuries appear to be a decisive factor for experimental polytrauma. Therefore, our aim was to compare the inflammatory response and organ damage of five different monotrauma with three multiple trauma models. For this, mice were randomly assigned to 10 groups: Healthy control (Ctrl), Sham, hemorrhagic shock (HS), thoracic trauma (TxT), osteotomy with external fixation (Fx), bilateral soft tissue trauma (bsTT) or laparotomy (Lap); polytrauma I (PT I, TxT + HS + Fx), PT II (TxT + HS + Fx + Lap) and one multi-trauma group (MT, TxT + HS + bsTT + Lap). The inflammatory response and organ damage were quantified at 6 h by analyses of IL-6, IL-1β, IL-10, CXCL1, SAA1, HMGB1 and organ injury. Systemic IL-6 increased in all mono and multiple trauma groups, while CXCL1 increased only in HS, PT I, PT II and MT vs. control. Local inflammatory response was most prominent in HS, PT I, PT II and MT in the liver. Infiltration of inflammatory cells into lung and liver was significant in all multiple trauma groups vs. controls. Hepatic and pulmonary injury was prominent in HS, PT I, PT II and MT groups. These experimental multiple trauma models closely mimic the early post-traumatic inflammatory response in human. Though, the choice of read-out parameters is very important for therapeutic immune modulatory approaches.

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.

Remote Intestinal Injury Early After Experimental Polytrauma and Hemorrhagic Shock

Dysfunction of the gut-blood barrier plays an important role in many diseases, such as inflammatory bowel disease, hemorrhagic shock (HS), or burn injury. However, little is known about gut barrier dysfunction after hemodynamically instable polytrauma (PT). Therefore, we aimed to evaluate the effects of PT and HS on remote intestinal damage and barrier dysfunction, especially regarding the role of zonula occludens protein 1 (ZO-1) as an important tight junction protein.Male C57BL/6 mice were subjected to either PT (thorax trauma, closed head injury, soft tissue injury, and distal femoral fracture), 60 min of pressure-controlled HS (30 ± 5 mmHg), or PT+HS, or sham procedures.Animals of all trauma groups showed an increase in abdominal girth and dilation of the intestine during the experimental period, which was largest in the PT+HS group. Increased blood-tissue permeability to albumin (assessed by Evans blue dye) was found in the HS group. Experimental groups showed a slight increase in plasma concentration of intestinal fatty acid binding protein and some intestinal damage was histologically detectable. Of note, PT+HS animals revealed significantly reduced expression of ZO-1 in intestinal epithelial cells. In an in-vitro model, stimulation of human colon epithelial cells with peptidoglycan, but not with lipopolysaccharide, resulted in elevated secretion of pro-inflammatory cytokines, reflecting inflammatory activity of the intestinal epithelium.Taken together, PT and HS lead to increased permeability of the gut-blood barrier. Bacterial components may lead to production of inflammatory and chemotactic mediators by gut epithelial cells, underlining the role of the gut as an immunologically active organ.

Time Course of Immune Response and Immunomodulation During Normal and Delayed Healing of Musculoskeletal Wounds

Single trauma injuries or isolated fractures are often manageable and generally heal without complications. In contrast, high-energy trauma results in multi/poly-trauma injury patterns presenting imbalanced pro- and anti- inflammatory responses often leading to immune dysfunction. These injuries often exhibit delayed healing, leading to fibrosis of injury sites and delayed healing of fractures depending on the intensity of the compounding traumas. Immune dysfunction is accompanied by a temporal shift in the innate and adaptive immune cells distribution, triggered by the overwhelming release of an arsenal of inflammatory mediators such as complements, cytokines and damage associated molecular patterns (DAMPs) from necrotic cells. Recent studies have implicated this dysregulated inflammation in the poor prognosis of polytraumatic injuries, however, interventions focusing on immunomodulating inflammatory cellular composition and activation, if administered incorrectly, can result in immune suppression and unintended outcomes. Immunomodulation therapy is promising but should be conducted with consideration for the spatial and temporal distribution of the immune cells during impaired healing. This review describes the current state of knowledge in the spatiotemporal distribution patterns of immune cells at various stages during musculoskeletal wound healing, with a focus on recent advances in the field of Osteoimmunology, a study of the interface between the immune and skeletal systems, in long bone fractures. The goals of this review are to (1) discuss wound and fracture healing processes of normal and delayed healing in skeletal muscles and long bones; (2) provide a balanced perspective on temporal distributions of immune cells and skeletal cells during healing; and (3) highlight recent therapeutic interventions used to improve fracture healing. This review is intended to promote an understanding of the importance of inflammation during normal and delayed wound and fracture healing. Knowledge gained will be instrumental in developing novel immunomodulatory approaches for impaired healing.

Alcohol‑induced attenuation of post‑traumatic inflammation is not necessarily liver‑protective following trauma/hemorrhage

Due to their high prevalence, blunt chest trauma (TxT) and hemorrhagic shock have a significant influence on the outcomes of trauma patients, causing severe modulations of the immune system and high mortality rates. Alcohol consumption in trauma patients has a high clinical impact. Studies investigating the timing of alcohol intoxication prior to trauma are limited, although there are two typical scenarios regarding alcohol consumption: Acute ('drink and drive scenario') and sub‑acute ('evening binge drinking'). Therefore, the present study investigated the influence of either an acute or sub‑acute alcohol‑drinking scenario in an in vivo model of TxT and hemorrhagic shock, focusing on liver inflammation and outcomes. At 12 h (sub‑acute) or 2 h (acute) before the experiment, female Lewis rats received a single oral dose of alcohol (ethanol, EtOH) or saline (NaCl, ctrl), followed by TxT, hemorrhagic shock (35±3 mm Hg) and resuscitation (H/R). The animals were either sacrificed 2 h later or their survival was determined for 72 h. The results revealed that EtOH induced significant fatty changes in the liver. TxT + H/R‑induced increases in the gene expression of interleukin (IL)‑6 and intercellular adhesion molecule‑1 and the protein expression of tumor necrosis factor (TNF)‑α and IL‑1β were significantly reduced in both EtOH groups compared with those in the corresponding TxT + H/R ctrl groups. The local presence of IL‑10‑expressing cells in the liver was significantly increased following TxT + H/R in all groups, although the sub‑acute EtOH TxT + H/R group had a significantly higher proportion of IL‑10‑positive cells compared with all other groups. Stimulating peripheral whole blood with lipopolysaccharide led to significantly lower levels of TNF‑α release in the sub‑acute EtOH group compared with the levels in all other groups. Significant TxT + H/R‑induced increases in liver transaminases and liver damage were most prominent in the sub‑acute EtOH group. The TxT + H/R EtOH group exhibited the lowest levels of glucose. There were no significant differences in mortality rate among the TxT + H/R groups. The data obtained indicates that the severity of liver damage following TxT + H/R may depend on the timing of alcohol consumption and severity of trauma, but also on the balance between pro‑ and anti‑inflammatory responses.

A concomitant bone fracture delays cognitive recovery from traumatic brain injury

BACKGROUND

Brain injury progression after severe traumatic brain injury (TBI) is associated with worsening cerebral inflammation but it is unknown how a concomitant bone fracture (BF) affects this progression. Enoxaparin (ENX) decreases penumbral leukocyte mobilization after TBI and improves neurologic recovery. We hypothesized that a concomitant BF worsens learning/memory recovery weeks after TBI and that ENX improves this recovery.

METHODS

CD1 male mice underwent controlled cortical impact or sham craniotomy with or without tibial fracture, receiving either daily ENX (0.8 mg/kg) or saline for 14 days after injury. Randomization defined four groups (Sham, TBI only, TBI + Fx, TBI + Fx + ENX, n = 5/each). Body weight loss and neurologic recovery (Garcia Neurologic Test, max score = 18) were assessed each day. Mouse learning (swimming time [s] and total distance [m] to reach the submerged platform Days 14 to 17 after TBI) and memory (swimming time [s] in platform quadrant after platform removed [probe]) was assessed by the Morris water maze. Ly-6G (cerebral neutrophil sequestration) and glial fibrillary acidic protein were evaluated by immunohistochemistry in brain tissue post mortem. Analysis of variance with Tukey's post hoc test determined significance (p < 0.05).

RESULTS

A concurrent BF worsened Garcia Neurologic Test scores post-TBI Days 2 to 4 (p < 0.01) as compared with TBI only, and ENX reversed this worsening on Day 4 (p < 0.01). Learning was significantly slower (greater swimming time and distance) in TBI + Fx versus TBI only on Day 17 (p < 0.01). This was despite similar swimming velocities in both groups, indicating intact extremity motor function. Memory was similar in isolated TBI and Sham which was significantly better than in TBI + Fx animals (p < 0.05). Glial fibrillary acidic protein-positive cells in penumbral cortex were most prevalent in TBI + Fx animals, significantly greater than in Sham (p < 0.05).

CONCLUSION

A long BF accompanying TBI worsens early neurologic recovery and subsequent learning/memory. Enoxaparin may partially counter this and improve neurologic recovery.

Traumatic injury pattern is of equal relevance as injury severity for experimental (poly)trauma modeling

This study aims to elaborate the relevance of trauma severity and traumatic injury pattern in different multiple and/or polytrauma models by comparing five singular trauma to two different polytrauma (PT) models with high and one multiple trauma (MT) model with low injury-severity score (ISS). The aim is to provide a baseline for reducing animal harm according to 3Rs by providing less injury as possible in polytrauma modeling. Mice were randomly assigned to 10 groups: controls (Ctrl; n = 15), Sham (n = 15); monotrauma groups: hemorrhagic shock (HS; n = 15), thoracic trauma (TxT; n = 18), osteotomy with external fixation (Fx; n = 16), bilateral soft tissue trauma (bSTT; n = 16) or laparotomy (Lap; n = 16); two PT groups: PT I (TxT + HS + Fx; ISS = 18; n = 18), PT II (TxT + HS + Fx + Lap; ISS = 22; n = 18), and a MT group (TxT + HS + bSTT + Lap, ISS = 13; n = 18). Activity and mortality were assessed. Blood gas analyses and organ damage markers were determined after 6 h. Significant mortality occurred in TxT, PT and MT (11.7%). Activity decreased significantly in TxT, HS, both polytrauma and MT vs. Ctrl/Sham. PT-groups and MT had significantly decreased activity vs. bsTT, Lap or Fx. MT had significantly lower pCO₂vs. Ctrl/Sham, Lap or bsTT. Transaminases increased significantly in PT-groups and MT vs. Ctrl, Sham or monotrauma. Traumatic injury pattern is of comparable relevance as injury severity for experimental multiple or (poly)trauma modeling.

Monotrauma is associated with enhanced remote inflammatory response and organ damage, while polytrauma intensifies both in porcine trauma model

AIM

Severely injured patients experience substantial immunological stress upon traumatic insult. Next to the direct local tissue injury also other organs, which are not directly injured such as liver and lung, are frequently affected by a so-called remote organ damage (ROD) after trauma. Thus, we studied the inflammatory response of lung and liver either after isolated femur fracture as example for ROD, or after multiple trauma in a porcine polytrauma model.

METHODS

Twenty-four male pigs (Sus scrofa) underwent either isolated standardized femoral fracture (monotrauma, MT, n = 12) or polytrauma (PT, n = 12). PT consisted of a femur fracture, lung contusion, liver laceration, hemorrhagic shock, subsequent resuscitation and surgical fracture fixation. Six animals served as controls (sham). After 72 h inflammatory changes were determined by analyses of the interleukin (IL)-6 gene expression and tissue infiltration of polymorphonuclear leukocyte (PMN, myeloperoxidase staining). ROD in MT, and lung as well as liver damage in PT were assessed histologically by hematoxylin-eosin staining. Expression of phosphorylated p65 NF-κB was evaluated by immunohistology.

RESULTS

IL-6 increased in lungs and liver in both groups MT and PT, respectively, compared to sham. Similarly, PMN infiltration of the lungs and liver increased significantly after both MT and PT compared to sham. Histological evaluation demonstrated tissue damage notably in lungs after MT, while tissue damage after PT was found in both lung and liver after PT. p65 NF-κB tended to an increase upon MT, and was significantly enhanced after PT in both tissues.

CONCLUSION

Our data indicate that remote organ damage after MT notably in lungs was associated with an enhanced inflammatory response. Severe polytrauma substantially intensifies this response and organ damage in the underlying model.

Penehyclidine hydrochloride exerts protective effects in rats with acute lung injury via the Fas/FasL signaling pathway

Acute lung injury (ALI) is a critical syndrome that is associated with high morbidity and mortality rates. The activation of the Fas/Fas ligand (FasL) signaling pathway may be an important pathophysiological mechanism during ALI development. Penehyclidine hydrochloride (PHC) has been revealed to exhibit anti-apoptotic properties and may attenuate the observed systemic inflammatory response. The present study was performed to elucidate the molecular mechanism of PHC in the regulation of the Fas/FasL signaling pathway in rats with ALI. An ALI rat model was constructed by inducing blunt chest trauma and hemorrhagic shock (T/HS), with PHC administration prior to or following T/HS. At 6 h following T/HS, blood samples and lung tissues were collected. Western blotting, arterial blood gas analysis, ELISA, hematoxylin and eosin staining, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining and biochemical indicator analysis were performed to determine the degree of lung injury and the key signaling pathways associated with lung damage. The results indicated that the administration of PHC following T/HS effectively attenuates lung injury by improving pulmonary oxygenation, decreasing histopathological damage, decreasing polymorphonuclear neutrophil count and decreasing Fas, FasL, caspase-8, caspase-3, tumor necrosis factor-α, interleukin (IL)-6 and IL-1β expression. The results indicated that PHC exhibits anti-apoptotic functions and exerts protective effects in ALI rats induced by T/HS, which may be attributed to the inhibition of the Fas/FasL signaling pathway.

Role of Hemorrhagic Shock in Experimental Polytrauma

Hemorrhagic shock (HS) after tissue trauma increases the complication and mortality rate of polytrauma (PT) patients. Although several murine trauma models have been introduced, there is a lack of knowledge about the exact impact of an additional HS. We hypothesized that HS significantly contributes to organ injury, which can be reliably monitored by detection of specific organ damage markers. Therefore we established a novel clinically relevant PT plus HS model in C57BL/6 mice which were randomly assigned to control, HS, PT, or PT+HS procedure (n = 8 per group). For induction of PT, anesthetized animals received a blunt chest trauma, head injury, femur fracture, and soft tissue injury. HS was induced by pressure-controlled blood drawing (mean arterial blood pressure of 30 mmHg for 60 min) and mice then resuscitated with ionosterile (4 × volume drawn), monitored, and killed for blood and organ harvesting 4 h after injury. After HS and resuscitation, PT+HS mice required earlier and overall more catecholamine support than HS animals to keep their mean arterial blood pressure. HS significantly contributed to the systemic release of interleukin-6 and high mobility group box 1 protein. Furthermore, the histological lung injury score, pulmonary edema, neutrophil influx, and plasma clara cell protein 16 were all significantly enhanced in PT animals in the presence of an additional HS. Although early morphological changes were minor, HS also contributed functionally to remote acute kidney injury but not to early liver damage. Moreover, PT-induced systemic endothelial injury, as determined by plasma syndecan-1 levels, was significantly aggravated by an additional HS. These results indicate that HS adds to the systemic inflammatory reaction early after PT. Within hours after PT, HS seems to aggravate pulmonary damage and to worsen renal and endothelial function which might overall contribute to the development of early multiple organ dysfunction.

Orthopedic Injured versus Uninjured Comparison Groups for Neuroimaging Research in Mild Traumatic Brain Injury

To address controversy surrounding the most appropriate comparison group for mild traumatic brain injury (mTBI) research, mTBI patients 12-30 years of age were compared with an extracranial orthopedic injury (OI) patient group and an uninjured, typically developing (TD) participant group with comparable demographic backgrounds. Injured participants underwent subacute (within 96 h) and late (3 months) diffusion tensor imaging (DTI); TD controls underwent DTI once. Group differences in fractional anisotropy (FA) and mean diffusivity (MD) of commonly studied white matter tracts were assessed. For FA, subacute group differences occurred in the bilateral inferior frontal occipital fasciculus (IFOF) and right inferior longitudinal fasciculus (ILF), and for MD, differences were found in the total corpus callosum, right uncinate fasciculus, IFOF, ILF, and bilateral cingulum bundle (CB). In these analyses, differences (lower FA and higher MD) were generally observed between the mTBI and TD groups but not between the mTBI and OI groups. After a 3 month interval, groups significantly differed in left IFOF FA and in right IFOF and CB MD; the TD group had significantly higher FA and lower MD than both injury groups, which did not differ. There was one exception to this pattern, in which the OI group demonstrated significantly lower FA in the left ILF than the TD group, although neither group differed from the mTBI group. The mTBI and OI groups had generally similar longitudinal results. Findings suggest that different conclusions about group-level DTI analyses could be drawn, depending on the selected comparison group, highlighting the need for additional research in this area. Where possible, mTBI studies may benefit from the inclusion of both OI and TD controls.

Diet-Induced Obesity Affects Muscle Regeneration After Murine Blunt Muscle Trauma-A Broad Spectrum Analysis

Injury to skeletal muscle affects millions of people worldwide. The underlying regenerative process however, is a very complex mechanism, time-wise highly coordinated, and subdivided in an initial inflammatory, a regenerative and a remodeling phase. Muscle regeneration can be impaired by several factors, among them diet-induced obesity (DIO). In order to evaluate if obesity negatively affects healing processes after trauma, we utilized a blunt injury approach to damage the extensor iliotibialis anticus muscle on the left hind limb of obese and normal weight C57BL/6J without showing any significant differences in force input between normal weight and obese mice. Magnetic resonance imaging (MRI) of the injury and regeneration process revealed edema formation and hemorrhage exudate in muscle tissue of normal weight and obese mice. In addition, morphological analysis of physiological changes revealed tissue necrosis, immune cell infiltration, extracellular matrix (ECM) remodeling, and fibrosis formation in the damaged muscle tissue. Regeneration was delayed in muscles of obese mice, with a higher incidence of fibrosis formation due to hampered expression levels of genes involved in ECM organization. Furthermore, a detailed molecular fingerprint in different stages of muscle regeneration underlined a delay or even lack of a regenerative response to injury in obese mice. A time-lapse heatmap determined 81 differentially expressed genes (DEG) with at least three hits in our model at all-time points, suggesting key candidates with a high impact on muscle regeneration. Pathway analysis of the DEG revealed five pathways with a high confidence level: myeloid leukocyte migration, regulation of tumor necrosis factor production, CD4-positive, alpha-beta T cell differentiation, ECM organization, and toll-like receptor (TLR) signaling. Moreover, changes in complement-, Wnt-, and satellite cell-related genes were found to be impaired in obese animals after trauma. Furthermore, histological satellite cell evaluation showed lower satellite cell numbers in the obese model upon injury. Ankrd1, C3ar1, Ccl8, Mpeg1, and Myog expression levels were also verified by qPCR. In summary, increased fibrosis formation, the reduction of Pax7⁺ satellite cells as well as specific changes in gene expression and signaling pathways could explain the delay of tissue regeneration in obese mice post trauma.

Comparative Analysis of the Regulatory T Cells Dynamics in Peripheral Blood in Human and Porcine Polytrauma

Background

Severely injured patients experience substantial immunological stress in the aftermath of traumatic insult, which often results in systemic immune dysregulation. Regulatory T cells (Treg) play a key role in the suppression of the immune response and in the maintenance of immunological homeostasis. Little is known about their presence and dynamics in blood after trauma, and nothing is known about Treg in the porcine polytrauma model. Here, we assessed different subsets of Treg in trauma patients (TP) and compared those to either healthy volunteers (HV) or data from porcine polytrauma.

Methods

Peripheral blood was withdrawn from 20 TP with injury severity score (ISS) ≥16 at the admittance to the emergency department (ED), and subsequently on day 1 and at day 3. Ten HV were included as controls (ctrl). The porcine polytrauma model consisted of a femur fracture, liver laceration, lung contusion, and hemorrhagic shock resulting in an ISS of 27. After polytrauma, the animals underwent resuscitation and surgical fracture fixation. Blood samples were withdrawn before and immediately after trauma, 24 and 72 h later. Different subsets of Treg, CD4+CD25+, CD4+CD25+FoxP3+, CD4+CD25+CD127-, and CD4+CD25+CD127-FoxP3+ were characterized by flow cytometry.

Results

Absolute cell counts of leukocytes were significantly increasing after trauma, and again decreasing in the follow-up in human and porcine samples. The proportion of human Treg in the peripheral blood of TP admitted to the ED was lower when compared to HV. Their numbers did not recover until 72 h after trauma. Comparable data were found for all subsets. The situation in the porcine trauma model was comparable with the clinical data. In porcine peripheral blood before trauma, we could identify Treg with the typical immunophenotype (CD4+CD25+CD127-), which were virtually absent immediately after trauma. Similar to the human situation, most of these cells expressed FoxP3, as assessed by intracellular FACS stain.

Conclusion

Despite minor percental differences in the recovery of Treg populations after trauma, our findings show a comparable decrease of Treg early after polytrauma, and strengthen the immunological significance of the porcine polytrauma model. Furthermore, the Treg subpopulation CD4+CD25+CD127- was characterized in porcine samples.

The influence of immunological stressors on traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide, and typically involves a robust immune response. Although a great deal of preclinical research has been conducted to identify an effective treatment, all phase III clinical trials have been unsuccessful to date. These translational shortcomings are in part due to a failure to recognize and account for the heterogeneity of TBI, including how extracranial factors can influence the aftermath of TBI. For example, most preclinical studies have utilized isolated TBI models in young adult males, while clinical trials typically involve highly heterogeneous patient populations (e.g., different mechanisms of injury, a range of ages, presence of polytrauma or infection). This paper will review the current, albeit limited literature related to how TBI is affected by common concomitant immunological stressors. In particular, discussion will focus on whether extracranial trauma (i.e., polytrauma), infection, and age/immunosenescence can influence TBI pathophysiology, and thereby may result in a different brain injury than what would have occurred in an isolated TBI. It is concluded that these immunological stressors are all likely to be TBI modifiers that should be further studied and could impact translational treatment strategies.

MDSCs are induced after experimental blunt chest trauma and subsequently alter antigen-specific T cell responses

Severe blunt chest trauma (TxT) induces a strong inflammatory response with posttraumatic immune suppression pointing to an impaired adaptive immune response. Since CD11b⁺Gr-1⁺-expressing myeloid-derived suppressor cells (MDSCs) are induced after inflammation and suppress T cell responses, MDSC induction and their impact on T cell functions was analysed in an experimental TxT model. MDSCs were induced preferentially in the lung until 24 hours after TxT. Although MDSC numbers were only faintly increased in the spleen, splenic MDSCs isolated after TxT strongly inhibited alloantigen-induced T cell proliferation in vitro. Suppressive activity correlated with increased expression of arginase-1 and iNOS. MDSCs also prevented antigen-induced T cell expansion in vivo, since staphylococcus enterotoxin B (SEB)-induced proliferation of vβ8⁺ T cells was impaired in TxT mice in the presence of CD11b⁺Gr-1⁺ cells. Surprisingly, MDSCs were not involved in shifting T cells into Th2 cells, characterized by the secretion of cytokines impairing cell-mediated immunity and promoting immunosuppression. Instead, the presence of CD11b⁺Gr-1⁺ cells was required for efficient IL-2, IFN-γ and TNFα production after antigenic stimulation, indicating, that elevation of MDSCs early after traumatic injuries might contribute to restrict the initial inflammatory response by alleviating T cell expansion, however, without impeding Th1 functions.

Investigation of surfactant protein-D and interleukin-6 levels in patients with blunt chest trauma with multiple rib fractures and pulmonary contusions: a cross-sectional study in Black Sea Region of Turkey

OBJECTIVE

Multiple rib fractures (RFs) and pulmonary contusions (PCs), with resulting systemic lung inflammation, are the most common injuries caused by blunt chest trauma (BCT) in motor vehicle accidents. This study examined levels of the inflammation marker interleukin (IL)-6 and those of the acute-phase reactant surfactant protein (SP)-D in patients with BCT.

DESIGN

Prospective, cross-sectional, observational study.

SETTING

Single-centre, tertiary care hospital in the Black Sea Region of Turkey.

PARTICIPANTS

The study included 60 patients with BCT who were hospitalised in our thoracic surgery department.

PARAMETERS MEASURES

The SP-D and IL-6 serum levels of patients with RFs (two or more RFs) (n=30) and patients with PCs (n=30) were measured after 6 hours, 24 hours and 7 days, and compared with those of age-matched and gender-matched healthy participants.

RESULTS

The 6-hour serum SP-D levels of the RFs (p=0.017) and PCs (p<0.001) groups were significantly higher than those of the healthy controls. The 24-hour and 7-day SP-D levels of both groups were also higher than the control group. The serum IL-6 levels of both groups were significantly higher than those of the control group. We have found Injury Severity Score to be independently related to 6-hour IL-6 (β=1.414, p<0.001) and 24-hour IL-6 levels (β=1.067, p<0.001). The development of complications was independently related to 6-hour SP-D level (β=0.211, p=0.047).

CONCLUSIONS

RFs and PCs after BCT lead to local and systemic inflammation due to lung injury. The levels of the systemic inflammation marker IL-6 and those of the acute-phase reactant SP-D were elevated in the present study. The SP-D level may be used as a marker in the follow-up of BCT-related complications.

Role of Complement C5 in Experimental Blunt Chest Trauma-Induced Septic Acute Lung Injury (ALI)

BACKGROUND

Severe blunt chest trauma is associated with high mortality. Sepsis represents a serious risk factor for mortality in acute respiratory distress syndrome (ARDS). In septic patients with ARDS complement activation products were found to be elevated in the plasma. In single models like LPS or trauma complement has been studied to some degree, however in clinically highly relevant double hit models such as the one used here little data is available. Here, we hypothesized that absence of C5 is correlated with a decreased inflammatory response in trauma induced septic acute lung injury.

METHODS

12 hrs after DH in mice the local and systemic cytokines and chemokines were quantified by multiplex bead array or ELISA, activated caspase-3 by western blot. Data were analyzed using one-way ANOVA followed by post-hoc Sidak's multiple comparison test (significance, p≤ 0.05).

RESULTS

In lung tissue interleukin (IL)-6, monocyte chemo attractant protein-1 (MCP-1) and granulocyte-colony stimulating factor (G-CSF) was elevated in both C5-/- mice and wildtype littermates (wt), whereas caspase-3 was reduced in lungs after DH in C5-/- mice. Systemically, reduced keratinocyte-derived chemokine (KC) levels were observed after DH in C5-/- compared to wt mice. Locally, lung myeloperoxidase (MPO), protein, IL-6, MCP-1 and G-CSF in brochoalveolar lavage fluid (BALF) were elevated after DH in C5-/- compared to wt.

CONCLUSIONS

In the complex but clinically relevant DH model the local and systemic inflammatory immune response features both, C5-dependent and C5-independent characteristics. Activation of caspase-3 in lung tissue after DH was C5-dependent whereas local inflammation in lung tissue was C5-independent.

The effect of concomitant peripheral injury on traumatic brain injury pathobiology and outcome

Background

Traumatic injuries are physical insults to the body that are prevalent worldwide. Many individuals involved in accidents suffer injuries affecting a number of extremities and organs, otherwise known as multitrauma or polytrauma. Traumatic brain injury is one of the most serious forms of the trauma-induced injuries and is a leading cause of death and long-term disability. Despite over dozens of phase III clinical trials, there are currently no specific treatments known to improve traumatic brain injury outcomes. These failures are in part due to our still poor understanding of the heterogeneous and evolving pathophysiology of traumatic brain injury and how factors such as concomitant extracranial injuries can impact these processes.

Main body

Here, we review the available clinical and pre-clinical studies that have investigated the possible impact of concomitant injuries on traumatic brain injury pathobiology and outcomes. We then list the pathophysiological processes that may interact and affect outcomes and discuss promising areas for future research. Taken together, many of the clinical multitrauma/polytrauma studies discussed in this review suggest that concomitant peripheral injuries may increase the risk of mortality and functional deficits following traumatic brain injury, particularly when severe extracranial injuries are combined with mild to moderate brain injury. In addition, recent animal studies have provided strong evidence that concomitant injuries may increase both peripheral and central inflammatory responses and that structural and functional deficits associated with traumatic brain injury may be exacerbated in multiply injured animals.

Conclusions

The findings of this review suggest that concomitant extracranial injuries are capable of modifying the outcomes and pathobiology of traumatic brain injury, in particular neuroinflammation. Though additional studies are needed to further identify the factors and mechanisms involved in central and peripheral injury interactions following multitrauma and polytrauma, concomitant injuries should be recognized and accounted for in future pre-clinical and clinical traumatic brain injury studies.

Early Detection of Junctional Adhesion Molecule-1 (JAM-1) in the Circulation after Experimental and Clinical Polytrauma

Severe tissue trauma-induced systemic inflammation is often accompanied by evident or occult blood-organ barrier dysfunctions, frequently leading to multiple organ dysfunction. However, it is unknown whether specific barrier molecules are shed into the circulation early after trauma as potential indicators of an initial barrier dysfunction. The release of the barrier molecule junctional adhesion molecule-1 (JAM-1) was investigated in plasma of C57BL/6 mice 2 h after experimental mono- and polytrauma as well as in polytrauma patients (ISS ≥ 18) during a 10-day period. Correlation analyses were performed to indicate a linkage between JAM-1 plasma concentrations and organ failure. JAM-1 was systemically detected after experimental trauma in mice with blunt chest trauma as a driving force. Accordingly, JAM-1 was reduced in lung tissue after pulmonary contusion and JAM-1 plasma levels significantly correlated with increased protein levels in the bronchoalveolar lavage as a sign for alveolocapillary barrier dysfunction. Furthermore, JAM-1 was markedly released into the plasma of polytrauma patients as early as 4 h after the trauma insult and significantly correlated with severity of disease and organ dysfunction (APACHE II and SOFA score). The data support an early injury- and time-dependent appearance of the barrier molecule JAM-1 in the circulation indicative of a commencing trauma-induced barrier dysfunction.

Physiological and immune-biological characterization of a long-term murine model of blunt chest trauma

Blunt chest trauma causes pulmonary and systemic inflammation. It is still a matter of debate whether the long-term course of this inflammatory response is associated with persistent impairment of lung function. We hypothesized that an increase of inflammatory biomarkers may still be present at later time points after blunt chest trauma, eventually, despite normalized lung mechanics and gas exchange. Anesthetized spontaneously breathing male C57BL/6J mice underwent a blast wave-induced blunt chest trauma or sham procedure. Twelve and 24 h later, blood gases and lung mechanics were measured, together with blood, bronchoalveolar lavage (BAL), and tissue cytokine concentrations (multiplex cytokine kit); heme oxygenase 1 (HO-1), activated caspase-3, Bcl-xL, and Bax expression (Western blotting); nuclear factor-κB activation (electrophoretic mobility shift assay); nitrotyrosine formation; and purinergic (P2XR4 and P2XR7) receptor expression (immunohistochemistry). Histological damage was assessed by hematoxylin and eosin and periodic acid-Schiff staining. High-resolution respirometry allowed assessing mitochondrial respiration in diaphragm biopsies. Chest trauma significantly increased tissue and BAL cytokine levels, associated with a significant increase in HO-1, purinergic receptor expression, and tissue nitrotyrosine formation. In contrast, lung mechanics, gas exchange, and histological damage did not show any significant difference between sham and trauma groups. Activation of the immune response remains present at later time points after murine blunt chest trauma. Discordance of the increased local inflammatory response and preserved pulmonary function may be explained by a dissociation of the immune response and lung function, such as previously suggested after experimental sepsis.

Current Concepts in Orthopedic Management of Multiple Trauma

Multiple trauma patients frequently present challenging clinical scenarios with musculoskeletal injuries being the most common indications for surgical procedures in these patients. Despite our substantial knowledge, a universally approved objective definition for “multiple trauma” is yet to be delineated. Several controversial aspects of economics, pathophysiology, animal models, diagnosis, management and outcome of patients with multiple trauma have recently been explored and although some progress has been made, it seems that the available evidence is still inconclusive in some occasions. This manuscript revisits several current concepts of multiple trauma that have been the focus of recent investigation. We aim to provide the reader with an updated perspective based on the most recently published literature in the field of multiple trauma.

Ultrastructural lung pathology following brain injury combined with femur shaft fracture in a rat model

BACKGROUND

This study aimed to explore the early pathologic changes in the lung ultrastructure in rat models of isolated or multiple traumatic injuries.

METHODS

Ninety-six rats were divided into a control group, a unilateral femur fracture group, a brain injury group, and a unilateral femur fracture combined with brain injury group. At 1, 6, 12, and 24 hours following model creation, the rat lungs were isolated and examined under a transmission electron microscope. A lung injury scoring model was used to evaluate the ultrastructural changes in the organelles of Type II alveolar epithelial cells (AEC-II). The ultrastructural changes and lung injury scores were compared among the four groups.

RESULTS

Mild ultrastructural damage was seen in the single-trauma groups. In the unilateral femur fracture group, the organelle morphology alleviated within 24 hours. The brain injury group showed more obvious ultrastructural changes, and some organelles were irreversibly damaged. This ultrastructural damage to the AEC-II was significantly augmented in the combined injury group; in this group, the damage was most obvious, occurred the earliest, involved the widest area, continued to progress throughout the study, and apparently worsened in 24 hours. The lung injury scores increased at all the time points in the three experimental groups compared with the control group and were significantly higher in the combined injury group than in the other groups.

CONCLUSION

Ultrastructural AEC-II damage was significantly augmented in the combined injury model compared with the single-injury models. The pulmonary condition should be considered when treating this type of injury.

The quest for a universal definition of polytrauma: a trauma registry-based validation study

BACKGROUND

A pilot validation recommended defining polytrauma as patients with an Abbreviated Injury Scale (AIS) score greater than 2 in at least two Injury Severity Score (ISS) body regions (2 × AIS score > 2). This study aimed to validate this definition on larger data set. We hypothesized that patients defined by the 2 × AIS score > 2 cutoff have worse outcomes and use more resources than those without 2 × AIS score > 2 and that this would therefore be a better definition of polytrauma.

METHODS

Patients injured between 2009 and 2011, with complete documentation of AIS by New South Wales Trauma Registry and 16 years and older were selected. Age and sex were obtained in addition to outcomes of ISS, hospital length of stay (LOS), intensive care unit (ICU) admission, ICU LOS, and mortality. We compared demographic characteristics and outcomes between patients with ISS greater than 15 who did and did not meet the 2 × AIS score > 2 definition. We then undertook regression analyses (logistic regression for binary outcomes [ICU admission and death] and linear regression for hospital and ICU LOS) to compare outcomes for patients with and without 2 × AIS score > 2, adjusting for sex and age categories.

RESULTS

In the adjusted analyses, patients with 2 × AIS score > 2 had twice the odds of being admitted to the ICU compared with those without 2 × AIS score > 2 (odds ratio, 2.5; 95% confidence interval [CI], 2.2-2.8) and 1.7 times the odds of dying (95% CI, 1.4-2.0; p < 0.001 for both models). Patients with 2 × AIS score > 2 also had a mean difference of 1.5 days longer stay in the hospital compared with those without 2 × AIS score > 2 (95% CI, 1.4-1.7) and 1.6 days longer ICU stay (95% CI, 1.4-1.8; p < 0.001 for all models).

CONCLUSION

Patients with 2 × AIS score > 2 had higher mortality, more frequent ICU admissions, and longer hospital and ICU stay than those without 2 × AIS score > 2 and represents a superior definition to the definitions for polytrauma currently in use.

LEVEL OF EVIDENCE

Diagnostic test/ criteria, level III.

Long-term outcome analysis of liver transplantation for severe hepatic trauma

BACKGROUND

Liver transplantation (LTX) for severe hepatic trauma and its sequelae is a rare but potentially lifesaving option at the far end of the operative spectrum.

METHODS

This study analyzes 12 cases with LTX for hepatic trauma and its consequences from two transplant centers. A total of 2,701 consecutive liver transplants unrelated to trauma served as a control group. χ and Mann-Whitney U-tests, Kaplan-Meier analysis with log-rank tests, and Cox regression analysis were applied. Addressed were issues before, during, and after LTX. Major study end points were patient and graft survival.

RESULTS

The posttrauma transplant recipients are significantly younger (p = 0.014), with a significantly shorter graft survival (p = 0.038), resulting in a significantly higher retransplantation rate (p = 0.043). Of the 12 patients, 11 underwent surgical treatment for hepatic trauma before LTX with 7 of 12 patients experiencing liver necrosis at the time of LTX. Short-term survival and long-term survival are not significantly different between trauma and nontrauma patients. Severity of liver trauma (Moore Score) and concomitant injuries (Injury Severity Score [ISS]) have no significant impact on patient and graft survival. Four patients with hepatic trauma were treated with two-stage LTX with anhepatic phases between 14 hours and 28 hours. Two of those patients reached long-term survival (20-22 years).

CONCLUSION

LTX for severe liver trauma and its consequences seems justified in extreme cases. The high frequency of liver necrosis at the time of LTX may indicate possible shortcomings in liver packing technique or liver resection for hemorrhage control. Thus, severe hepatic trauma requires treatment by experienced liver surgeons and emergency physicians.

LEVEL OF EVIDENCE

Therapeutic study, level IV.