Trauma alarmins as activators of damage-induced inflammation

C-Reactive Protein Stimulates Nicotinic Acetylcholine Receptors to Control ATP-Mediated Monocytic Inflammasome Activation

Blood levels of the acute phase reactant C-reactive protein (CRP) are frequently measured as a clinical marker for inflammation, but the biological functions of CRP are still controversial. CRP is a phosphocholine (PC)-binding pentraxin, mainly produced in the liver in response to elevated levels of interleukin-1β (IL-1β) and of the IL-1β-dependent cytokine IL-6. While both cytokines play important roles in host defense, excessive systemic IL-1β levels can cause life-threatening diseases such as trauma-associated systemic inflammation. We hypothesized that CRP acts as a negative feedback regulator of monocytic IL-1β maturation and secretion. Here, we demonstrate that CRP, in association with PC, efficiently reduces ATP-induced inflammasome activation and IL-1β release from human peripheral blood mononuclear leukocytes and monocytic U937 cells. Effective concentrations are in the range of marginally pathologic CRP levels (IC50 = 4.9 µg/ml). CRP elicits metabotropic functions at nicotinic acetylcholine (ACh) receptors (nAChRs) containing subunits α7, α9, and α10 and suppresses the function of ATP-sensitive P2X7 receptors in monocytic cells. Of note, CRP does not induce ion currents at conventional nAChRs, suggesting that CRP is a potent nicotinic agonist controlling innate immunity without entailing the risk of adverse effects in the nervous system. In a prospective study on multiple trauma patients, IL-1β plasma concentrations negatively correlated with preceding CRP levels, whereas inflammasome-independent cytokines IL-6, IL-18, and TNF-α positively correlated. In conclusion, PC-laden CRP is an unconventional nicotinic agonist that potently inhibits ATP-induced inflammasome activation and might protect against trauma-associated sterile inflammation.

Mesenchymal Stromal Cell Preconditioning: The Next Step Toward a Customized Treatment For Severe Burn

Over the last century, the clinical management of severe skin burns significantly progressed with the development of burn care units, topical antimicrobials, resuscitation methods, early eschar excision surgeries, and skin grafts. Despite these considerable advances, the present treatment of severe burns remains burdensome, and patients are highly susceptible to skin engraftment failure, infections, organ dysfunction, and hypertrophic scarring. Recent researches have focused on mesenchymal stromal cell (MSC) therapy and hold great promises for tissue repair, as reported in several animal studies and clinical cases. In the present review, we will provide an up-to-date outlook of the pathophysiology of severe skin burns, clinical treatment modalities and current limitations. We will then focus on MSCs and their potential in the burn wound healing both in in vitro and in vivo studies. A specific attention will be paid to the cell preconditioning approach, as a means of improving the MSC efficacy in the treatment of major skin burns. In particular, we will debate how several preconditioning cues would modulate the MSC properties to better match up with the burn pathophysiology in the course of the cell therapy. Finally, we will discuss the clinical interest and feasibility of a MSC-based therapy in comparison to their paracrine derivatives, including microvesicles and conditioned media for the treatment of major skin burn injuries.

Trauma-Induced Damage-Associated Molecular Patterns-Mediated Remote Organ Injury and Immunosuppression in the Acutely Ill Patient

Trauma is one of the leading causes of death and disability in the world. Multiple trauma or isolated traumatic brain injury are both indicative of human tissue damage. In the early phase after trauma, damage-associated molecular patterns (DAMPs) are released and give rise to sterile systemic inflammatory response syndrome (SIRS) and organ failure. Later, protracted inflammation following sepsis will favor hospital-acquired infection and will worsen patient’s outcome through immunosuppression. Throughout medical care or surgical procedures, severe trauma patients will be subjected to endogenous or exogenous DAMPs. In this review, we summarize the current knowledge regarding DAMP-mediated SIRS or immunosuppression and the clinical consequences in terms of organ failure and infections.

Danger signals in trauma

This review summarizes a short list of currently discussed trauma-induced danger-associated molecular patterns (DAMP). Due to the bivalent character and often pleiotropic effects of a DAMP, it is difficult to describe its "friend or foe" role in post-traumatic inflammation and regeneration, both systemically as well locally in tissues. DAMP can be used as biomarkers to indicate or monitor disease or injury severity, but also may serve as clinically applicable parameters for better indication and timing of surgery. Due to the inflammatory processes at the local tissue level or the systemic level, the precise role of DAMP is not always clear to define. While in vitro and experimental studies allow for the detection of these biomarkers at the different levels of an organism-cellular, tissue, circulation-this is not always easily transferable to the human setting. Increased knowledge exploring the dual role of DAMP after trauma, and concentrating on their nuclear functions, transcriptional targets, release mechanisms, cellular sources, multiple functions, their interactions and potential therapeutic targeting is warranted.

β-Nicotinamide Adenine Dinucleotide (β-NAD) Inhibits ATP-Dependent IL-1β Release from Human Monocytic Cells

While interleukin-1β (IL-1β) is a potent pro-inflammatory cytokine essential for host defense, high systemic levels cause life-threatening inflammatory syndromes. ATP, a stimulus of IL-1β maturation, is released from damaged cells along with β-nicotinamide adenine dinucleotide (β-NAD). Here, we tested the hypothesis that β-NAD controls ATP-signaling and, hence, IL-1β release. Lipopolysaccharide-primed monocytic U937 cells and primary human mononuclear leukocytes were stimulated with 2'(3')-O-(4-benzoyl-benzoyl)ATP trieethylammonium salt (BzATP), a P2X7 receptor agonist, in the presence or absence of β-NAD. IL-1β was measured in cell culture supernatants. The roles of P2Y receptors, nicotinic acetylcholine receptors (nAChRs), and Ca²⁺-independent phospholipase A2 (iPLA2β, PLA2G6) were investigated using specific inhibitors and gene-silencing. Exogenous β-NAD signaled via P2Y receptors and dose-dependently (IC₅₀ = 15 µM) suppressed the BzATP-induced IL-1β release. Signaling involved iPLA2β, release of a soluble mediator, and nAChR subunit α9. Patch-clamp experiments revealed that β-NAD inhibited BzATP-induced ion currents. In conclusion, we describe a novel triple membrane-passing signaling cascade triggered by extracellular β-NAD that suppresses ATP-induced release of IL-1β by monocytic cells. This cascade links activation of P2Y receptors to non-canonical metabotropic functions of nAChRs that inhibit P2X7 receptor function. The biomedical relevance of this mechanism might be the control of trauma-associated systemic inflammation.

The source of cell-free mitochondrial DNA in trauma and potential therapeutic strategies

Mitochondria play a key role in the pathophysiology of post-injury inflammation. Cell-free mitochondrial DNA (cf-mtDNA) is now understood to catalyse sterile inflammation after trauma. Observations in trauma cohorts have identified high cf-mtDNA in patients with systemic inflammatory response syndrome and multiple organ failure as well as following major surgery. The source of cf-mtDNA can be various cells affected by mechanical and hypoxic injury (passive mechanism) or induced by inflammatory mechanisms (active mechanism). Multiple forms of cf-mtDNA exist; mtDNA fragments, mtDNA in microparticles/vesicles and cell-free mitochondria. Trauma to cells that are rich in mitochondria are believed to release more cf-mtDNA. This review describes the current understanding of the mechanisms of cf-mtDNA release, its systemic effects and the potential therapeutic implications related to its modification. Although current understanding is insufficient to change trauma management, focussed research goals have been identified to pave the way for monitoring and manipulation of cf-mtDNA release and effects in trauma.

Trained innate immunity: a salient factor in the pathogenesis of neuroimmune psychiatric disorders

Historically, only cells of the adaptive immune system have been considered capable of retaining memory for infectious challenges. Recently, however, cells of the innate immune system have been shown to be capable of displaying long-term functional memory following a single immunostimulatory challenge, leading to enhanced production of proinflammatory molecules upon other subsequent, and temporally distant, immunostimulatory challenges. This effect has been termed 'trained innate immunity', and is underwritten by stable epigenetic changes in immune and metabolic pathways. Importantly, the long-term training of innate immune cells can occur as a result of infectious as well as and non-infectious challenges, including stress. Given the role that both stress and an activated immune system have in neuropathology, innate immune training has important implications for our understanding and treatment of neuropsychiatric disorders. This review focuses on the evidence for trained innate immunity and highlights some insights into its relevance for psychiatric diseases.

Traumatic Injury

Traumatic injury as one of the world's most relevant but neglected health concerns results in modulated inflammasome activity, which is closely linked to the development of post-injury complications. Cytokine-producing capacity of cells is important for the appropriate immune response to trauma and requires not only synthesis and transcription of inflammasome components but also their activation. Unfortunately, the precise role of inflammasome in trauma is still largely unknown. However, in the following chapter, we provide an overview on the best described inflammasomes in the various settings of trauma, introducing the recent findings on the up-to-date best described NLRP inflammasomes and underlying cytokines in the inflammatory response to trauma.

Cardiac Depression in Pigs after Multiple Trauma - Characterization of Posttraumatic Structural and Functional Alterations

The purpose of this study was to define the relationship between cardiac depression and morphological and immunological alterations in cardiac tissue after multiple trauma. However, the mechanistic basis of depressed cardiac function after trauma is still elusive. In a porcine polytrauma model including blunt chest trauma, liver laceration, femur fracture and haemorrhage serial trans-thoracic echocardiography was performed and correlated with cellular cardiac injury as well as with the occurrence of extracellular histones in serum. Postmortem analysis of heart tissue was performed 72 h after trauma. Ejection fraction and shortening fraction of the left ventricle were significantly impaired between 4 and 27 h after trauma. H-FABP, troponin I and extracellular histones were elevated early after trauma and returned to baseline after 24 and 48 h, respectively. Furthermore, increased nitrotyrosine and Il-1β generation and apoptosis were identified in cardiac tissue after trauma. Main structural findings revealed alteration of connexin 43 (Cx43) and co-translocation of Cx43 and zonula occludens 1 to the cytosol, reduction of α-actinin and increase of desmin in cardiomyocytes after trauma. The cellular and subcellular events demonstrated in this report may for the first time explain molecular mechanisms associated with cardiac dysfunction after multiple trauma.

Hypertonic saline attenuates the cytokine-induced pro-inflammatory signature in primary human lung epithelia

Trauma/hemorrhagic shock is a complex physiological phenomenon that leads to dysregulation of many molecular pathways. For over a decade, hypertonic saline (HTS) has been used as an alternative resuscitation fluid in the setting of trauma/hemorrhagic shock. In addition to restoring circulating volume within the vascular space, studies have shown a positive immunomodulatory effect of HTS. Targeted studies have shown that HTS affects the transcription of several pro-inflammatory cytokines by inhibiting the NF-κB-IκB pathway in model cell lines and rats. However, few studies have been undertaken to assess the unbiased effects of HTS on the whole transcriptome. This study was designed to interrogate the global transcriptional responses induced by HTS and provides insight into the underlying molecular mechanisms and pathways affected by HTS. In this study, RNA sequencing was employed to explore early changes in transcriptional response, identify key mediators, signaling pathways, and transcriptional modules that are affected by HTS in the presence of a strong inflammatory stimulus. Our results suggest that primary human small airway lung epithelial cells (SAECS) exposed to HTS in the presence and absence of a strong pro-inflammatory stimulus exhibit very distinct effects on cellular response, where HTS is highly effective in attenuating cytokine-induced pro-inflammatory responses via mechanisms that involve transcriptional regulation of inflammation which is cell type and stimulus specific. HTS is a highly effective anti-inflammatory agent that inhibits the chemotaxis of leucocytes towards a pro-inflammatory gradient and may attenuate the progression of both the innate and adaptive immune response.

Occurrence of Dermatomyositis Immediately after Mastectomy Subsequent to Severe Chemotherapeutic Drug Eruption

We herein report a patient with breast cancer who developed dermatomyositis (DM) immediately after mastectomy. She had a history of severe drug eruption during neoadjuvant chemotherapy six months previously. Within a month after the operation, myalgia and rash, including Gottron's papules, developed, and skeletal-muscle enzymes elevated, so she was diagnosed with probable DM according to the Bohan and Peter criteria. In many neoplastic DM cases, the course of the disease parallels the course of the malignancy. Possible mechanisms were suggested to explain the development of DM in the present case and offer new insight into autoimmune diseases.

S100A8/A9 and sRAGE kinetic after polytrauma; an explorative observational study

Background

Following tissue injury after trauma, the activation of innate immune pathways results in systemic inflammation, organ failure and an increased risk of infections. The objective of this study was to characterize the kinetics of the S100A8/S100A9 complex, a new-recognized alarmin, as well as its soluble receptor sRAGE, over time after trauma as potential early biomarkers of the risk of organ damage.

Methods

We collected comprehensive data from consenting patients admitted to an ICU following severe trauma. The blood samples were taken at Day 0 (admission), Day1, 3 and 5 S100A8/A9 and sRAGE were measured by ELISA. Biomarkers levels were reported as median (IQR).

Results

Thirty-eight patients sustaining in majority a blunt trauma (89%) with a median ISS of 39 were included. In this cohort, the S100A8/A9 complex increased significantly over time (p = 0.001), but its levels increment over time (D0 to D5) was significantly smaller in patients developing infection (7.6 vs 40.1 mcg/mL, p = 0.011). The circulating level of sRAGE circulating levels decreased over time (p < 0.0001) and was higher in patients who remained in shock on day 3 (550 vs 918 pg/mL; p = 0.02) or 5 (498 vs 644 pg/mL; p = 0.045). Admission sRAGE levels were significantly higher in non-survivors (1694 vs 745 pg/mL; p = 0.015) and was higher in patients developing renal failure (1143 vs 696 pg/mL, p = 0.011).

Discussion

Our findings reveal an interesting association between the biomarker S100A8/9 least increase over time and the presence of infectious complication after trauma. We describe that the sRAGE decline over time is in relation with shock and markers of ischemic injury. We also confirm the association of sRAGE levels measured at admission with mortality and the development of renal failure.

Conclusions

This work illustrates the importance of following the circulating level of biomarker overtime. The utilization of S1008/9 as a tool to stratify infection risk and trigger early interventions need to be validated prospectively.

Experimental blunt chest trauma-induced myocardial inflammation and alteration of gap-junction protein connexin 43

OBJECTIVE

Severe blunt chest trauma in humans is associated with high mortality rates. Whereas lung tissue damage and lung inflammation after blunt chest trauma have extensively been investigated, the traumatic and posttraumatic effects on the heart remain poorly understood. Therefore, the purpose of this study was to define cardiac injury patterns in an experimental blunt chest trauma model in rats.

METHODS

Experimental blunt chest trauma was induced by a blast wave in rats, with subsequent analysis of its effects on the heart. The animals were subjected either to a sham or trauma procedure. Systemic markers for cardiac injury were determined after 24 h and 5 days. Postmortem analysis of heart tissue addressed structural injury and inflammation 24 h and 5 days after trauma.

RESULTS

Plasma levels of extracellular histones were elevated 24 h and 5 days after blunt chest trauma compared to sham-treated animals. In the heart, up-regulation of interleukin-1β 24 h after trauma and increased myeloperoxidase activity 24 h and 5 days after trauma were accompanied by reduced complement C5a receptor-1 expression 24 h after trauma. Histological analysis revealed extravasation of erythrocytes and immunohistochemical analysis alteration of the pattern of the gap-junction protein connexin 43. Furthermore, a slight reduction of α-actinin and desmin expression in cardiac tissue was found after trauma together with a minor increase in sarcoplasmatic/endoplasmatic reticlulum calcium-ATPase (SERCA) expression.

CONCLUSIONS

The clinically highly relevant rat model of blast wave-induced blunt chest trauma is associated with cardiac inflammation and structural alterations in cardiac tissue.

The Role of the Immune System Beyond the Fight Against Infection

The immune system was identified as a protective factor during infectious diseases over a century ago. Current definitions and textbook information are still largely influenced by these early observations, and the immune system is commonly presented as a defence machinery. However, host defence is only one manifestation of the immune system's overall function in the maintenance of tissue homeostasis and system integrity. In fact, the immune system is integral part of fundamental physiological processes such as development, reproduction and wound healing, and a close crosstalk between the immune system and other body systems such as metabolism, the central nervous system and the cardiovascular system is evident. Research and medical professionals in an expanding range of areas start to recognise the implications of the immune system in their respective fields.This chapter provides a brief historical perspective on how our understanding of the immune system has evolved from a defence system to an overarching surveillance machinery to maintain tissue integrity. Current perspectives on the non-defence functions of classical immune cells and factors will also be discussed.

Modeling DNA damage-induced pneumopathy in mice: insight from danger signaling cascades

Radiation-induced pneumonitis and fibrosis represent severe and dose-limiting side effects in the radiotherapy of thorax-associated neoplasms leading to decreased quality of life or - as a consequence of treatment with suboptimal radiation doses - to fatal outcomes by local recurrence or metastatic disease. It is assumed that the initial radiation-induced damage to the resident cells triggers a multifaceted damage-signalling cascade in irradiated normal tissues including a multifactorial secretory program. The resulting pro-inflammatory and pro-angiogenic microenvironment triggers a cascade of events that can lead within weeks to a pronounced lung inflammation (pneumonitis) or after months to excessive deposition of extracellular matrix molecules and tissue scarring (pulmonary fibrosis).The use of preclinical in vivo models of DNA damage-induced pneumopathy in genetically modified mice has helped to substantially advance our understanding of molecular mechanisms and signalling molecules that participate in the pathogenesis of radiation-induced adverse late effects in the lung. Herein, murine models of whole thorax irradiation or hemithorax irradiation nicely reproduce the pathogenesis of the human disease with respect to the time course and the clinical symptoms. Alternatively, treatment with the radiomimetic DNA damaging chemotherapeutic drug Bleomycin (BLM) has frequently been used as a surrogate model of radiation-induced lung disease. The advantage of the BLM model is that the symptoms of pneumonitis and fibrosis develop within 1 month.Here we summarize and discuss published data about the role of danger signalling in the response of the lung tissue to DNA damage and its cross-talk with the innate and adaptive immune systems obtained in preclinical studies using immune-deficient inbred mouse strains and genetically modified mice. Interestingly we observed differences in the role of molecules involved in damage sensing (TOLL-like receptors), damage signalling (MyD88) and immune regulation (cytokines, CD73, lymphocytes) for the pathogenesis and progression of DNA damage-induced pneumopathy between the models of pneumopathy induced by whole thorax irradiation or treatment with the radiomimetic drug BLM. These findings underline the importance to pursue studies in the radiation model(s) if we are to unravel the mechanisms driving radiation-induced adverse late effects.A better understanding of the cross-talk of danger perception and signalling with immune activation and repair mechanisms may allow a modulation of these processes to prevent or treat radiation-induced adverse effects. Vice-versa an improved knowledge of the normal tissue response to injury is also particularly important in view of the increasing interest in combining radiotherapy with immune checkpoint blockade or immunotherapies to avoid exacerbation of radiation-induced normal tissue toxicity.

Rapid Activation of Transforming Growth Factor β-Activated Kinase 1 in Chondrocytes by Phosphorylation and K63 -Linked Polyubiquitination Upon Injury to Animal Articular Cartilage

Objective

Mechanical injury to cartilage predisposes to osteoarthritis (OA). Wounding of the articular cartilage surface causes rapid activation of MAP kinases and NF‐κB, mimicking the response to inflammatory cytokines. This study was undertaken to identify the upstream signaling mechanisms involved.

Methods

Cartilage was injured by dissecting it from the articular surface of porcine metacarpophalangeal (MCP) joints or by avulsing murine proximal femoral epiphyses. Protein phosphorylation was assayed by Western blotting of cartilage lysates. Immunolocalization of phosphorylated activating transcription factor 2 (ATF‐2) and NF‐κB/p65 was detected by confocal microscopy. Messenger RNA (mRNA) was measured by quantitative reverse transcriptase–polymerase chain reaction (qRT‐PCR). Receptor associated protein 80 (RAP‐80) ubiquitin interacting motif agarose was used in a pull‐down assay to obtain K⁶³‐polyubiquitinated proteins. Ubiquitin linkages on immunoprecipitated transforming growth factor β–activated kinase 1 (TAK‐1) were analyzed with deubiquitinases.

Results

Sharp injury to porcine cartilage caused rapid activation of JNK and NF‐κB pathways and the upstream kinases MKK‐4, IKK, and TAK‐1. Pharmacologic inhibition of TAK‐1 in porcine cartilage abolished JNK and NF‐κB activation and reduced the injury‐dependent inflammatory gene response. High molecular weight species of phosphorylated TAK‐1 were induced by injury, indicating its ubiquitination. An overall increase in K⁶³‐linked polyubiquitination was detected upon injury, and TAK‐1 was specifically linked to K⁶³‐ but not K⁴⁸‐polyubiquitin chains. In mice, avulsion of wild‐type femoral epiphyses caused similar intracellular signaling that was reduced in cartilage‐specific TAK‐1–null mice. Epiphyseal cartilage of MyD88‐null and TRAF‐6–null mice responded to injury, suggesting the involvement of a ubiquitin E3 ligase other than TRAF‐6.

Conclusion

Activation of TAK‐1 by phosphorylation and K⁶³‐linked polyubiquitination by injury indicates its role in driving cell activation. Further studies are needed to identify the upstream ubiquitination mechanisms, including the E3 ligase involved.

An oligodeoxynucleotide with AAAG repeats significantly attenuates burn-induced systemic inflammatory responses via inhibiting interferon regulatory factor 5 pathway

Previously, we showed that an oligodeoxynucleotide with AAAG repeats (AAAG ODN) rescued mice from fatal acute lung injury (ALI) induced by influenza virus and inhibited production of tumor necrosis factor-α (TNF-α) in the injured lungs. However, the underlying mechanisms remain to be elucidated. Upon the bioinformatic analysis revealing that the AAAG ODN is consensus to interferon regulatory factor 5 (IRF5) binding site in the cis-regulatory elements of proinflammatory cytokines, we tried to explore whether the AAAG ODN could attenuate burn injury induced systemic inflammatory responses via inhibiting IRF5 pathway. Using the mouse model with sterile systemic inflammation induced by burn injury, we found that AAAG ODN prolonged the life span of the mice, decreased the expression of IRF5 at injured skin, reduced the production of TNF-α and IL-6 in blood and injured skin, and attenuated the ALI. Furthermore, AAAG ODN could bind IRF5 and inhibit the nuclear translocation of IRF5 in THP-1 cells. The data suggested that the AAAG ODN could act as a cytoplasmic decoy capable of interfering the function of IRF5, and be developed as a drug candidate for the treatment of inflammatory diseases.

Cold-inducible RNA-binding protein through TLR4 signaling induces mitochondrial DNA fragmentation and regulates macrophage cell death after trauma

Trauma is a major cause of systemic inflammatory response syndrome and multiple organ dysfunction syndrome. Macrophages (Mϕ) direct trauma-induced inflammation, and Mϕ death critically influences the progression of the inflammatory response. In the current study, we explored an important role of trauma in inducing mitochondrial DNA (mtDNA) damage in Mϕ and the subsequent regulation of Mϕ death. Using an animal pseudo-fracture trauma model, we demonstrated that tissue damage induced NADPH oxidase activation and increased the release of reactive oxygen species via cold-inducible RNA-binding protein (CIRP)–TLR4–MyD88 signaling. This in turn, activates endonuclease G, which serves as an executor for the fragmentation of mtDNA in Mϕ. We further showed that fragmented mtDNA triggered both p62-related autophagy and necroptosis in Mϕ. However, autophagy activation also suppressed Mϕ necroptosis and pro-inflammatory responses. This study demonstrates a previously unidentified intracellular regulation of Mϕ homeostasis in response to trauma.

Does neuroinflammation drive the relationship between tau hyperphosphorylation and dementia development following traumatic brain injury?

A history of traumatic brain injury (TBI) is linked to an increased risk for the later development of dementia. This encompasses a variety of neurodegenerative diseases including Alzheimer's Disease (AD) and chronic traumatic encephalopathy (CTE), with AD linked to history of moderate-severe TBI and CTE to a history of repeated concussion. Of note, both AD and CTE are characterized by the abnormal accumulation of hyperphosphorylated tau aggregates, which are thought to play an important role in the development of neurodegeneration. Hyperphosphorylation of tau leads to destabilization of microtubules, interrupting axonal transport, whilst tau aggregates are associated with synaptic dysfunction. The exact mechanisms via which TBI may promote the later tauopathy and its role in the later development of dementia are yet to be fully determined. Following TBI, it is proposed that axonal injury may provide the initial perturbation of tau, by promoting its dissociation from microtubules, facilitating its phosphorylation and aggregation. Altered tau dynamics may then be exacerbated by the chronic persistent inflammatory response that has been shown to persist for decades following the initial impact. Importantly, immune activation has been shown to play a role in accelerating disease progression in other tauopathies, with pro-inflammatory cytokines, like IL-1β, shown to activate kinases that promote tau hyperphosphorylation. Thus, targeting the inflammatory response in the sub-acute phase following TBI may represent a promising target to halt the alterations in tau dynamics that may precede overt neurodegeneration and later development of dementia.

Mechanism and effect of excessive inflammatory response in perioperative period of abdominal surgery

Inflammation is an important pathophysiological change in the perioperative period of abdominal surgery. Moderate inflammatory plays a positive role in wound healing, but excessive inflammation is harmful to the body and is a major cause of postoperative complications and the common pathway of multiple organ dysfunction syndrome. Therefore, intervention of excessive inflammation response in the perioperative period can reduce the morbidity and mortality of patients. However, the current understanding of the pathophysiological process of excessive inflammatory response during the perioperative period is still in the primary stage. This article systematically reviews the induced factors, mechanism and pathophysiological changes of excessive inflammatory response during the perioperative period of abdominal surgery as well as its harm to and influence on the body.

Toll-like receptor responses are suppressed in trauma ICU patients

BACKGROUND

Inflammation and activation of the innate immune system are often associated with traumatic injury and may involve alterations in toll-like receptor (TLR)-mediated responses.

METHODS

A prospective observational study was designed and conducted. Twenty-one severely injured (ISS = 16-41) trauma intensive care unit (ICU) patients and six healthy volunteers that served as controls were enrolled. Anticoagulated whole blood was collected at 2-12 d after ICU admission and incubated in the presence of media alone (baseline), zymosan (TLR2 agonist) or lipopolysaccharide (LPS; TLR4 agonist) for 3 h. Supernatant levels of inflammatory cytokines (IL-1β, IL-6, IL-10, and TNFα) were determined.

RESULTS

TLR2-mediated and TLR4-mediated activation of whole blood cell cultures from both healthy volunteers and subjects-induced elevated cytokine levels over that observed in unstimulated cultures. Baseline values of IL-6 were significantly elevated in subject cultures as compared to healthy volunteers. Healthy volunteer cultures had 2-3-fold greater levels of IL-6 and TNFα than subject cultures when stimulated with zymosan (TLR2 agonist) or LPS (TLR4 agonist). IL-1β and IL-10 levels did not differ significantly between healthy volunteers and subjects.

CONCLUSIONS

The ability of circulating leukocytes from trauma ICU patients to be activated by TLR agonists is markedly suppressed and may play a role in the development of subsequent infectious complications.

Pumping the Brakes: Neurotrophic Factors for the Prevention of Cognitive Impairment and Dementia after Traumatic Brain Injury

Traumatic brain injury (TBI) is the leading cause of disability and death worldwide, affecting as many as 54,000,000-60,000,000 people annually. TBI is associated with significant impairments in brain function, impacting cognitive, emotional, behavioral, and physical functioning. Although much previous research has focused on the impairment immediately following injury, TBI may have much longer-lasting consequences, including neuropsychiatric disorders and cognitive impairment. TBI, even mild brain injury, has also been recognized as a significant risk factor for the later development of dementia and Alzheimer's disease. Although the link between TBI and dementia is currently unknown, several proposed mechanisms have been put forward, including alterations in glucose metabolism, excitotoxicity, calcium influx, mitochondrial dysfunction, oxidative stress, and neuroinflammation. A treatment for the devastating long-term consequences of TBI is desperately needed. Unfortunately, however, no such treatment is currently available, making this a major area of unmet medical need. Increasing the level of neurotrophic factor expression in key brain areas may be one potential therapeutic strategy. Of the neurotrophic factors, granulocyte-colony stimulating factor (G-CSF) may be particularly effective for preventing the emergence of long-term complications of TBI, including dementia, because of its ability to reduce apoptosis, stimulate neurogenesis, and increase neuroplasticity.

Neurogenic inflammation after traumatic brain injury and its potentiation of classical inflammation

Background

The neuroinflammatory response following traumatic brain injury (TBI) is known to be a key secondary injury factor that can drive ongoing neuronal injury. Despite this, treatments that have targeted aspects of the inflammatory pathway have not shown significant efficacy in clinical trials.

Main body

We suggest that this may be because classical inflammation only represents part of the story, with activation of neurogenic inflammation potentially one of the key initiating inflammatory events following TBI. Indeed, evidence suggests that the transient receptor potential cation channels (TRP channels), TRPV1 and TRPA1, are polymodal receptors that are activated by a variety of stimuli associated with TBI, including mechanical shear stress, leading to the release of neuropeptides such as substance P (SP). SP augments many aspects of the classical inflammatory response via activation of microglia and astrocytes, degranulation of mast cells, and promoting leukocyte migration. Furthermore, SP may initiate the earliest changes seen in blood-brain barrier (BBB) permeability, namely the increased transcellular transport of plasma proteins via activation of caveolae. This is in line with reports that alterations in transcellular transport are seen first following TBI, prior to decreases in expression of tight-junction proteins such as claudin-5 and occludin. Indeed, the receptor for SP, the tachykinin NK1 receptor, is found in caveolae and its activation following TBI may allow influx of albumin and other plasma proteins which directly augment the inflammatory response by activating astrocytes and microglia.

Conclusions

As such, the neurogenic inflammatory response can exacerbate classical inflammation via a positive feedback loop, with classical inflammatory mediators such as bradykinin and prostaglandins then further stimulating TRP receptors. Accordingly, complete inhibition of neuroinflammation following TBI may require the inhibition of both classical and neurogenic inflammatory pathways.

Bleeding related to disturbed fibrinolysis

The components and reactions of the fibrinolysis system are well understood. The pathway has fewer reactants and interactions than coagulation, but the generation of a complete quantitative model is complicated by the need to work at the solid‐liquid interface of fibrin. Diagnostic tools to detect disease states due to malfunctions in the fibrinolysis pathway are also not so well developed as is the case with coagulation. However, there are clearly a number of inherited or acquired pathologies where hyperfibrinolysis is a serious, potentially life‐threatening problem and a number of antifibrinolytc drugs are available to treat hyperfibrinolysis. These topics will be covered in the following review.

Blockade of Extracellular High-Mobility Group Box 1 Attenuates Systemic Inflammation and Coagulation Abnormalities in Rats with Acute Traumatic Coagulopathy

BACKGROUND As an extracellularly released mediator, high-mobility group box 1 (HMGB1) initiates sterile inflammation following severe trauma. Serum HMGB1 levels correlate well with acute traumatic coagulopathy (ATC) in trauma patients, which is independently associated with higher mortality. We investigated the involvement of HMGB1 in ATC through blocking extracellular HMGB1. MATERIAL AND METHODS The ATC model was induced by polytrauma and hemorrhage in male Sprague-Dawley rats, which were randomly assigned to sham, ATC, and ATCH (ATC with HMGB1 blockade) groups. Thrombelastography (TEG) was performed to monitor changes in coagulation function. Serum levels of HMGB1, TNF-α, and IL-6 were measured, as well as lung levels of HMGB1 and nuclear factor (NF)-κB and expression of receptor for advanced glycation end-products (RAGE). RESULTS Compared with the sham group, HMGB1 increased the serum levels of TNF-α and IL-6, whereas HMGB1 blockade inhibited the induction of TNF-α and IL-6. HMGB1 also induced elevated serum soluble P-selectin and fibrinolysis markers plasmin-antiplasmin complex, which both were reduced by HMGB1 blockade. Thrombelastography revealed the hypocoagulability status in the ATC group, which was attenuated by anti-HMGB1 antibody. Furthermore, the lung level of NF-κB and expression of RAGE were decreased by anti-HMGB1 antibody, suggesting the role of RAGE/NF-κB pathway in ATC. CONCLUSIONS HMGB1 blockade can attenuate inflammation and coagulopathy in ATC rats. Anti-HMGB1 antibody might exert protective effects partly through the RAGE/NF-κB pathway. Thus, HMGB1 has potential as a therapeutic target in ATC.

Early changes within the lymphocyte population are associated with the development of multiple organ dysfunction syndrome in trauma patients

BACKGROUND

Early survival following severe injury has been improved with refined resuscitation strategies. Multiple organ dysfunction syndrome (MODS) is common among this fragile group of patients leading to prolonged hospital stay and late mortality. MODS after trauma is widely attributed to dysregulated inflammation but the precise mechanics of this response and its influence on organ injury are incompletely understood. This study was conducted to investigate the relationship between early lymphocyte responses and the development of MODS during admission.

METHODS

During a 24-month period, trauma patients were recruited from an urban major trauma centre to an ongoing, observational cohort study. Admission blood samples were obtained within 2 h of injury and before in-hospital intervention, including blood transfusion. The study population was predominantly male with a blunt mechanism of injury. Lymphocyte subset populations including T helper, cytotoxic T cells, NK cells and γδ T cells were identified using flow cytometry. Early cytokine release and lymphocyte count during the first 7 days of admission were also examined.

RESULTS

This study demonstrated that trauma patients who developed MODS had an increased population of NK dim cells (MODS vs no MODS: 22 % vs 13 %, p < 0.01) and reduced γδ-low T cells (MODS vs no MODS: 0.02 (0.01-0.03) vs 0.09 (0.06-0.12) × 10^9/L, p < 0.01) at admission. Critically injured patients who developed MODS (n = 27) had higher interferon gamma (IFN-γ) concentrations at admission, compared with patients of matched injury severity and shock (n = 60) who did not develop MODS (MODS vs no MODS: 4.1 (1.8-9.0) vs 1.0 (0.6-1.8) pg/ml, p = 0.01). Lymphopenia was observed within 24 h of injury and was persistent in those who developed MODS. Patients with a lymphocyte count of 0.5 × 10(9)/L or less at 48 h, had a 45 % mortality rate.

CONCLUSIONS

This study provides evidence of lymphocyte activation within 2 h of injury, as demonstrated by increased NK dim cells, reduced γδ-low T lymphocytes and high blood IFN-γ concentration. These changes are associated with the development of MODS and lymphopenia. The study reveals new opportunities for investigation to characterise the cellular response to trauma and examine its influence on recovery.

Catheter manipulation analysis for objective performance and technical skills assessment in transcatheter aortic valve implantation

PURPOSE

Transcatheter aortic valve implantation (TAVI) demands precise and efficient handling of surgical instruments within the confines of the aortic anatomy. Operational performance and dexterous skills are critical for patient safety, and objective methods are assessed with a number of manipulation features, derived from the kinematic analysis of the catheter/guidewire in fluoroscopy video sequences.

METHODS

A silicon phantom model of a type I aortic arch was used for this study. Twelve endovascular surgeons, divided into two experience groups, experts ([Formula: see text]) and novices ([Formula: see text]), performed cannulation of the aorta, representative of valve placement in TAVI. Each participant completed two TAVI experiments, one with conventional catheters and one with the Magellan robotic platform. Video sequences of the fluoroscopic monitor were recorded for procedural processing. A semi-automated tracking software provided the 2D coordinates of the catheter/guidewire tip. In addition, the aorta phantom was segmented in the videos and the shape of the entire catheter was manually annotated in a subset of the available video frames using crowdsourcing. The TAVI procedure was divided into two stages, and various metrics, representative of the catheter's overall navigation as well as its relative movement to the vessel wall, were developed.

RESULTS

Experts consistently exhibited lower values of procedure time and dimensionless jerk, and higher average speed and acceleration than novices. Robotic navigation resulted in increased average distance to the vessel wall in both groups, a surrogate measure of safety and reduced risk of embolisation. Discrimination of experience level and types of equipment was achieved with the generated motion features and established clustering algorithms.

CONCLUSIONS

Evaluation of surgical skills is possible through the analysis of the catheter/guidewire motion pattern. The use of robotic endovascular platforms seems to enable more precise and controlled catheter navigation.

Sterile post-traumatic immunosuppression

After major trauma, the human immune system initiates a series of inflammatory events at the injury site that is later followed by suppression of local inflammation favoring the repair and remodeling of the damaged tissues. This local immune response involves complex interactions between resident cells such as macrophages and dendritic cells, soluble mediators such as cytokines and chemokines, and recruited cells such as neutrophils, monocytes and mesenchymal stromal cells. If of sufficient magnitude, these initial immune responses nevertheless have systemic consequences resulting in a state called post-traumatic immunosuppression (PTI). However, controversy exists regarding the exact immunological changes occurring in systemic compartments triggered by these local immune responses. PTI is one of the leading causes of post-surgical mortality and makes patients vulnerable to hospital-acquired infections, multiple organ failure and many other complications. In addition, hemorrhage, blood transfusion, immunesenescence and immunosuppressant drugs aggravate PTI. PTI has been intensively studied, but published results are frequently cloudy. The purpose of this review is to focus on the contributions made by different responsive modalities to immunosuppression following sterile trauma and to try to integrate these into an overall scheme of PTI.

Immune Surveillance of the CNS following Infection and Injury

The central nervous system (CNS) contains a sophisticated neural network that must be constantly surveyed in order to detect and mitigate a diverse array of challenges. The innate and adaptive immune systems actively participate in this surveillance, which is critical for the maintenance of CNS homeostasis and can facilitate the resolution of infections, degeneration, and tissue damage. Infections and sterile injuries represent two common challenges imposed on the CNS that require a prompt immune response. While the inducers of these two challenges differ in origin, the resultant responses orchestrated by the CNS share some overlapping features. Here, we review how the CNS immunologically discriminates between pathogens and sterile injuries, mobilizes an immune reaction, and, ultimately, regulates local and peripherally-derived immune cells to provide a supportive milieu for tissue repair.

Innate danger signals in acute injury: From bench to bedside

The description of the systemic inflammatory response syndrome (SIRS) as a reaction to numerous insults marked a turning point in the understanding of acute critical states, which are intensive care basic cases. This concept highlighted the final inflammatory response features whichever the injury mechanism is: infectious, or non-infectious such as extensive burns, traumas, major surgery or acute pancreatitis. In these cases of severe non-infectious insult, many endogenous mediators are released. Like infectious agents components, they can activate the immune system (via common signaling pathways) and initiate an inflammatory response. They are danger signals or alarmins. These molecules generally play an intracellular physiological role and acquire new functions when released in extracellular space. Many progresses brought new information on these molecules and on their function in infectious and non-infectious inflammation. These danger signals can be used as biomarkers and provide new pathophysiological and therapeutic approaches, particularly for immune dysfunctions occurring after an acute injury. We present herein the danger model, the main danger signals and the clinical consequences.

Prolonged but not short-duration blast waves elicit acute inflammation in a rodent model of primary blast limb trauma

BACKGROUND

Blast injuries from conventional and improvised explosive devices account for 75% of injuries from current conflicts; over 70% of injuries involve the limbs. Variable duration and magnitude of blast wave loading occurs in real-life explosions and is hypothesised to cause different injuries. While a number of in vivo models report the inflammatory response to blast injuries, the extent of this response has not been investigated with respect to the duration of the primary blast wave. The relevance is that explosions in open air are of short duration compared to those in confined spaces.

METHODS

Hindlimbs of adult Sprauge-Dawley rats were subjected to focal isolated primary blast waves of varying overpressure (1.8-3.65kPa) and duration (3.0-11.5ms), utilising a shock tube and purpose-built experimental rig. Rats were monitored during and after the blast. At 6 and 24h after exposure, blood, lungs, liver and muscle tissues were collected and prepared for histology and flow cytometry.

RESULTS

At 6h, increases in circulating neutrophils and CD43Lo/His48Hi monocytes were observed in rats subjected to longer-duration blast waves. This was accompanied by increases in circulating pro-inflammatory chemo/cytokines KC and IL-6. No changes were observed with shorter-duration blast waves irrespective of overpressure. In all cases, no histological damage was observed in muscle, lung or liver. By 24h post-blast, all inflammatory parameters had normalised.

CONCLUSIONS

We report the development of a rodent model of primary blast limb trauma that is the first to highlight an important role played by blast wave duration and magnitude in initiating acute inflammatory response following limb injury in the absence of limb fracture or penetrating trauma. The combined biological and mechanical method developed can be used to further understand the complex effects of blast waves in a range of different tissues and organs in vivo.

Release mechanism of high mobility group nucleosome binding domain 1 from lipopolysaccharide-stimulated macrophages

Alarmins are identified as endogenous mediators that have potent immune-activating abilities. High mobility group nucleosome binding domain 1 (HMGN1), a highly conserved, non-histone chromosomal protein, which binds to the inner side of the nucleosomal DNA, regulates chromatin dynamics and transcription in cells. Furthermore, HMGN1 acts as a cytokine in the extracellular milieu by inducing the recruitment and maturation of antigen-presenting cells (dendritic cells) to enhance Th1-type antigen-specific immune responses. Thus, HMGN1 is expected to act as an alarmin, when released into the extracellular milieu. The present study investigated the release mechanism of HMGN1 from macrophages using mouse macrophage‑like RAW264.7 cells. The results indicated that HMGN1 was released from lipopolysaccharide (LPS)‑stimulated RAW264.7 cells, accompanied by cell death as assessed by the release of lactate dehydrogenase (LDH). Subsequently, the patterns of cell death involved in HMGN1 release from LPS‑stimulated RAW264.7 cells were determined using a caspase‑1 inhibitor, YVAD, and a necroptosis inhibitor, Nec‑1. YVAD and Nec‑1 did not alter LPS‑induced HMGN1 and LDH release, suggesting that pyroptosis (caspase‑1‑activated cell death) and necroptosis are not involved in the release of HMGN1 from LPS‑stimulated RAW264.7 cells. In addition, flow cytometric analysis indicated that LPS stimulation did not induce apoptosis but substantially augmented necrosis, as evidenced by staining with annexin V/propidium iodide. Together these findings suggest that HMGN1 is extracellularly released from LPS‑stimulated RAW264.7 macrophage‑like cells, accompanied by unprogrammed necrotic cell death but not pyroptosis, necroptosis or apoptosis.

The perioperative immune response

PURPOSE OF REVIEW

A host of immune modulators are now available in clinical practice. The perioperative period is characterized by profound alterations in host immunity, which can result in poor outcomes, which include infection, cancer recurrence and organ failure. Manipulation of the perioperative immune response has the potential to improve outcomes. A complete understanding of the mechanisms and clinical consequences of altered immune function in this setting is therefore imperative.

RECENT FINDINGS

Recent in-vivo data have emerged which further our understanding of the interaction between tissue damage, immune modulation and clinical outcomes by utilizing novel laboratory techniques capable of monitoring single-cell immune signatures. Traditional gene expression assays have continued to demonstrate their utility and have been instrumental in defining the host response to perioperative allogeneic blood transfusion. These mechanistic studies are complemented by large clinical studies describing associations between anaesthetic modalities and immune-related outcomes.

SUMMARY

Laboratory techniques are now available that can monitor the perioperative immune response and could be further developed to introduce personalized care pathways. Consideration must also be given to anaesthesia techniques and perioperative treatments that, although not immediately harmful, may be associated with poor outcomes temporally distant from the treatment, secondary to induced immunosuppression.

Pathogenesis of infection in surgical patients

Purpose of review

Despite the application of prophylactic antimicrobial therapy and advanced technologies, infection remains one of the most common causes of morbidity and mortality in surgical patients. Understanding the pathogenesis of surgical infection would offer new insights into the development of biomarkers to predict and stratify infection in patients, and to explore specific strategies to minimize this serious postoperative complication.

Recent findings

The acute nonspecific inflammatory response triggered by endogenous danger signals evoked by surgical insult is beneficial, while paradoxically associated with reduced resistance to infection. There is growing evidence indicating that primed inflammation by surgical insult exaggerates the dysregulation of the immune-inflammatory response to the invasion of pathogens postoperatively. Innate immune receptors, such as Toll-like receptors (TLRs), contribute to detecting both pathogen-associated molecular patterns and endogenous damage-associated molecular patterns, and to further amplifying inflammatory responses to infection. Current evidence shows the fascinating role of non-TLRs in the process of infection. Non-TLRs, such as membrane-associated triggering receptor expressed on myeloid cells family, cytosolic nucleotide-binding oligomerization domain-like receptors and nuclear receptor nuclear family 4 subgroup A receptors, are also crucial in triggering the immune responses and mounting an effective defense against surgical insults and the second hit of infection.

Summary

Understanding the pivotal role of non-TLRs in sensing exogenous and endogenous molecules, and the influence of primed systemic inflammation and depressed immune status on the defense against pathogen after surgical insult, would be helpful to fully explore the relevant sophisticated phenomena of surgical infection, and to elucidate the occurrence of heterogeneous constellations of clinical signs and symptoms among this special population.

Multiple Infectious Complications in a Severely Injured Patient with Single Nucleotide Polymorphisms in Important Innate Immune Response Genes

Trauma is a major public health problem worldwide. Infectious complications, sepsis, and multiple organ dysfunction syndrome (MODS) remain important causes for morbidity and mortality in patients who survive the initial trauma. There is increasing evidence for the role of genetic variation in the innate immune system on infectious complications in severe trauma patients. We describe a trauma patient with multiple infectious complications caused by multiple micro-organisms leading to prolonged hospital stay with numerous treatments. This patient had multiple single nucleotide polymorphisms (SNPs) in the MBL2, MASP2, FCN2 and TLR2 genes, most likely contributing to increased susceptibility and severity of infectious disease.

Are the paradigms in trauma disease changing?

Despite an annual trauma mortality of 5 million people worldwide, resulting in countless physical disabilities and enormous expenses, there are no standardized guidelines on trauma organization and management. Over the last few decades there have been very notorious improvements in severe trauma care, though organizational and economical aspects such as research funding still need to be better engineered. Indeed, trauma lags behind other serious diseases in terms of research and organization. The rapid developments in trauma care have produced original models available for research projects, initial resuscitation protocols and radiological procedures such as CT for the initial management of trauma patients, among other advances. This progress underscores the need for a multidisciplinary approach to the initial management and follow-up of this complicated patient population, where intensivists play a major role in both the patient admission and subsequent care at the trauma unit.

Inflammation and neuroprotection in traumatic brain injury

IMPORTANCE

Traumatic brain injury (TBI) is a significant public health concern that affects individuals in all demographics. With increasing interest in the medical and public communities, understanding the inflammatory mechanisms that drive the pathologic and consequent cognitive outcomes can inform future research and clinical decisions for patients with TBI.

OBJECTIVES

To review known inflammatory mechanisms in TBI and to highlight clinical trials and neuroprotective therapeutic manipulations of pathologic and inflammatory mechanisms of TBI.

EVIDENCE REVIEW

We searched articles in PubMed published between 1960 and August 1, 2014, using the following keywords: traumatic brain injury, sterile injury, inflammation, astrocytes, microglia, monocytes, macrophages, neutrophils, T cells, reactive oxygen species, alarmins, danger-associated molecular patterns, purinergic receptors, neuroprotection, and clinical trials. Previous clinical trials or therapeutic studies that involved manipulation of the discussed mechanisms were considered for inclusion. The final list of selected studies was assembled based on novelty and direct relevance to the primary focus of this review.

FINDINGS

Traumatic brain injury is a diverse group of sterile injuries induced by primary and secondary mechanisms that give rise to cell death, inflammation, and neurologic dysfunction in patients of all demographics. Pathogenesis is driven by complex, interacting mechanisms that include reactive oxygen species, ion channel and gap junction signaling, purinergic receptor signaling, excitotoxic neurotransmitter signaling, perturbations in calcium homeostasis, and damage-associated molecular pattern molecules, among others. Central nervous system resident and peripherally derived inflammatory cells respond to TBI and can provide neuroprotection or participate in maladaptive secondary injury reactions. The exact contribution of inflammatory cells to a TBI lesion is dictated by their anatomical positioning as well as the local cues to which they are exposed.

CONCLUSIONS AND RELEVANCE

The mechanisms that drive TBI lesion development as well as those that promote repair are exceedingly complex and often superimposed. Because pathogenic mechanisms can diversify over time or even differ based on the injury type, it is important that neuroprotective therapeutics be developed and administered with these variables in mind. Due to its complexity, TBI has proven particularly challenging to treat; however, a number of promising therapeutic approaches are now under pre-clinical development, and recent clinical trials have even yielded a few successes. Given the worldwide impact of TBI on the human population, it is imperative that research remains active in this area and that we continue to develop therapeutics to improve outcome in afflicted patients.

Reconstitution fluid type does not affect pulmonary inflammation or DNA damage following infusion of lyophilized plasma

BACKGROUND

Dysfunctional inflammation following traumatic hemorrhage can lead to multiple-organ failure and death. In our polytrauma swine model, lyophilized plasma (LP) reconstituted with sterile water and ascorbic acid suppressed systemic inflammation and attenuated DNA damage. However, it remains unknown whether the inflammatory response is affected by the type of fluid used to reconstitute LP. We hypothesized that common resuscitation fluids such as normal saline (LP-NS), lactated Ringer's solution (LP-LR), Hextend (LP-HX), or sterile water (LP-SW) would yield similar inflammation profiles and DNA damage following LP reconstitution and transfusion.

METHODS

This was a randomized, prospective, blinded animal study. LP was reconstituted to 50% of original volume with NS, LR, HX, or SW buffered with 15-mM ascorbic acid. Forty swine were subjected to a validated model of polytrauma, hemorrhagic shock, and Grade V liver injury and resuscitated with LP. Serum interleukin 6 (IL-6), IL-10, plasma C-reactive protein, and 8-hydroxy-2-deoxyguanosine concentrations were assessed for systemic inflammation and DNA damage at baseline, 2 hours, and 4 hours following liver injury. Lung inflammation was evaluated by Real Time Polymerize Chain Reaction (RT-PCR).

RESULTS

Reconstituted LP pH was similar between groups before resuscitation. IL-6 and IL-10 increased at 2 hours and 4 hours compared with baseline in all groups (p < 0.017). DNA damage increased at 2 hours and 4 hours compared with baseline and from 2 hours to 4 hours in the LP-NS, LP-LR, and LP-SW groups (all p < 0.017). Animals resuscitated with LP-HX not only demonstrated increased DNA damage at 4 hours versus baseline but also had the lowest C-reactive protein level at 2 hours and 4-hours (p < 0.017). Overall, differences between groups were similar for DNA damage and lung inflammation.

CONCLUSION

Reconstitution fluid type does not affect inflammatory cytokine profiles or DNA damage following LP transfusion in this swine polytrauma model. Based on universal availability, these data suggest that sterile water is the most logical choice for LP reconstitution in humans.

LEVEL OF EVIDENCE

Prognostic, level II.

Local hemostasis, immunothrombosis, and systemic disseminated intravascular coagulation in trauma and traumatic shock

Knowing the pathophysiology of trauma-induced coagulopathy is important for the management of severely injured trauma patients. The aims of this review are to provide a summary of the recent advances in our understanding of thrombosis and hemostasis following trauma and to discuss the pathogenesis of disseminated intravascular coagulation (DIC) at an early stage of trauma. Local hemostasis and thrombosis respectively act to induce physiological wound healing of injuries and innate immune responses to damaged-self following trauma. However, if overwhelmed by systemic inflammation caused by extensive tissue damage and tissue hypoperfusion, both of these processes foster systemic DIC associated with pathological fibrin(ogen)olysis. This is called DIC with the fibrinolytic phenotype, which is characterized by the activation of coagulation, consumption coagulopathy, insufficient control of coagulation, and increased fibrin(ogen)olysis. Irrespective of microvascular thrombosis, the condition shows systemic thrombin generation as well as its activation in the circulation and extensive damage to the microvasculature endothelium. DIC with the fibrinolytic phenotype gives rise to oozing-type non-surgical bleeding and greatly affects the prognosis of trauma patients. The coexistences of hypothermia, acidosis, and dilution aggravate DIC and lead to so-called trauma-induced coagulopathy.

He that would know what shall be must consider what has been.

The Analects of Confucius.

Effect of pharmacologic resuscitation on the brain gene expression profiles in a swine model of traumatic brain injury and hemorrhage

BACKGROUND

We have previously shown that addition of valproic acid (VPA; a histone deacetylase inhibitor) to hetastarch (Hextend [HEX]) resuscitation significantly decreases lesion size in a swine model of traumatic brain injury (TBI) and hemorrhagic shock (HS). However, the precise mechanisms have not been well defined. As VPA is a transcriptional modulator, the aim of this study was to investigate its effect on brain gene expression profiles.

METHODS

Swine were subjected to controlled TBI and HS (40% blood volume), kept in shock for 2 hours, and resuscitated with HEX or HEX + VPA (n = 5 per group). Following 6 hours of observation, brain RNA was isolated, and gene expression profiles were measured using a Porcine Gene ST 1.1 microarray (Affymetrix, Santa Clara, CA). Pathway analysis was done using network analysis tools Gene Ontology, Ingenuity Pathway Analysis, and Parametric Gene Set Enrichment Analysis. Real-time polymerase chain reaction was used to verify the key microarray findings.

RESULTS

A total of 1,668 probe sets mapping to 370 known genes were differentially expressed between the HEX and HEX + VPA groups. Expression of apoptotic genes differed between groups, and biologic function analysis predicted a significant downregulation of apoptosis (p = 1.29 × 10), cell death (p = 8.46 × 10), and necrosis (p = 9.07 × 10). Pathway analysis indicated a significant modulation of pathways involved in cell signaling, dendritic cell response, and the complement system.

CONCLUSION

This is the first high-throughput analysis of cerebral gene profiling following TBI + HS. It shows that treatment with VPA significantly alters early transcription of pathways related to cell survival, which may explain its neuroprotective effects.

The impact of surgical timing and intervention on outcome in traumatized dogs and cats

OBJECTIVE

To review the relevant human and veterinary literature regarding the timing of surgical intervention for trauma patients and the impact on outcome.

DATA SOURCES

Original research, clinical studies, and review articles with no date restrictions from both human and veterinary literature.

HUMAN DATA SYNTHESIS

Despite extensive research into the ideal timing of surgical intervention for human trauma victims, debate is ongoing and views are still evolving. Prior to the 1970s, the standard of care consisted of delayed surgical treatment, as these patients were considered too ill to undergo surgery. Beginning in the 1970s, and continuing for nearly 2 decades, early definitive surgical treatment was recommended. The most recent evolution of human trauma management incorporates the concept of damage control surgery, which acknowledges the importance of early skeletal stabilization or laparotomy for reducing morbidity while attempting to avoid complications such as acute respiratory distress syndrome or multiple organ dysfunction syndrome.

VETERINARY DATA SYNTHESIS

Despite a relatively large amount of literature available regarding veterinary trauma, no evidence exists to provide the clinician guidance as to the ideal timing of surgery for trauma patients. With the exception of diaphragmatic hernia, no studies were identified that attempted to evaluate this variable.

CONCLUSIONS

Veterinary-specific studies are needed to evaluate the impact of surgical timing on outcome following trauma. The information that can be obtained from studies in this area can improve veterinary trauma care and may be used as models for human trauma care through translational applications.

Inflammatory response to trauma: implications for coagulation and resuscitation

PURPOSE OF REVIEW

Recent studies have changed our understanding of the timing and interactions of the inflammatory processes and coagulation cascade following severe trauma. This review highlights this information and correlates its impact on the current clinical approach for fluid resuscitation and treatment of coagulopathy for trauma patients.

RECENT FINDINGS

Severe trauma is associated with a failure of multiple biologic emergency response systems that includes imbalanced inflammatory response, acute coagulopathy of trauma, and endovascular glycocalyx degradation with microcirculatory compromise. These abnormalities are all interlinked and related. Recent observations show that after severe trauma: proinflammatory and anti-inflammatory responses are concomitant, not sequential and resolution of the inflammatory response is an active process, not a passive one. Understanding these interrelated processes is considered extremely important for the development of future therapies for severe trauma in humans.

SUMMARY

Traumatic injuries continue to be a significant cause of mortality worldwide. Recent advances in understanding the mechanisms of end-organ failure, and modulation of the inflammatory response has important clinical implications regarding fluid resuscitation and treatment of coagulopathy.

The systemic immune response to trauma: an overview of pathophysiology and treatment

Improvements in the control of haemorrhage after trauma have resulted in the survival of many people who would otherwise have died from the initial loss of blood. However, the danger is not over once bleeding has been arrested and blood pressure restored. Two-thirds of patients who die following major trauma now do so as a result of causes other than exsanguination. Trauma evokes a systemic reaction that includes an acute, non-specific, immune response associated, paradoxically, with reduced resistance to infection. The result is damage to multiple organs caused by the initial cascade of inflammation aggravated by subsequent sepsis to which the body has become susceptible. This Series examines the biological mechanisms and clinical implications of the cascade of events caused by large-scale trauma that leads to multiorgan failure and death, despite the stemming of blood loss. Furthermore, the stark and robust epidemiological finding--namely, that age has a profound influence on the chances of surviving trauma irrespective of the nature and severity of the injury--will be explored. Advances in our understanding of the inflammatory response to trauma, the impact of ageing on this response, and how this information has led to new and emerging treatments aimed at combating immune dysregulation and reduced immunity after injury will also be discussed.

Prevention of tissue hypoperfusion in the trauma patient: initial management

This article outlines the challenges of identification and management of tissue hypoperfusion as a consequence of haemorrhagic shock in civilian polytrauma cases. It also describes damage resuscitation, but does not cover specific trauma cases such as pregnancy, burns, head injuries, children and elderly trauma.

PKCδ-IRAK1 axis regulates oxidized LDL-induced IL-1β production in monocytes

This study examined the role of interleukin (IL)-1 receptor-associated kinase (IRAK) and protein kinase C (PKC) in oxidized LDL (Ox-LDL)-induced monocyte IL-1β production. In THP1 cells, Ox-LDL induced time-dependent secretory IL-1β and IRAK1 activity; IRAK4, IRAK3, and CD36 protein expression; PKCδ-JNK1 phosphorylation; and AP-1 activation. IRAK1/4 siRNA and inhibitor (INH)-attenuated Ox-LDL induced secreted IL-1β and pro-IL-1β mRNA and pro-IL-1β and mature IL-1β protein expression, respectively. Diphenyleneiodonium chloride (NADPH oxidase INH) and N-acetylcysteine (free radical scavenger) attenuated Ox-LDL-induced reactive oxygen species generation, caspase-1 activity, and pro-IL-1β and mature IL-1β expression. Ox-LDL-induced secretory IL-1β production was abrogated in the presence of JNK INH II, Tanshinone IIa, Ro-31-8220, Go6976, Rottlerin, and PKCδ siRNA. PKCδ siRNA attenuated the Ox-LDL-induced increase in IRAK1 kinase activity, JNK1 phosphorylation, and AP-1 activation. In THP1 macrophages, CD36, toll-like receptor (TLR)2, TLR4, TLR6, and PKCδ siRNA prevented Ox-LDL-induced PKCδ and IRAK1 activation and IL-1β production. Enhanced Ox-LDL and IL-1β in systemic inflammatory response syndrome (SIRS) patient plasma demonstrated positive correlation with each other and with disease severity scores. Ox-LDL-containing plasma induced PKCδ and IRAK1 phosphorylation and IL-1β production in a CD36-, TLR2-, TLR4-, and TLR6-dependent manner in primary human monocytes. Results suggest involvement of CD36, TLR2, TLR4, TLR6, and the PKCδ-IRAK1-JNK1-AP-1 axis in Ox-LDL-induced IL-1β production.