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

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.

Multicompartmental Trauma Induces Persistent Inflammation and Organ Injury

INTRODUCTION

Previous preclinical models of multicompartmental injury have investigated its effects for durations of less than 72 h and the long-term effects have not been defined. We hypothesized that a model of multicompartmental injury would result in systemic inflammation and multiorgan dysfunction that persists at 1 wk.

METHODS

Male and proestrus female Sprague-Dawley rats (n = 16/group) underwent polytrauma (PT) (unilateral right lung contusion, hemorrhagic shock, cecectomy, bifemoral pseudofractures) and were compared to naive controls. Weight, hemoglobin, plasma neutrophil gelatinase-associated lipocalin, and plasma toll-like receptor 4 were evaluated on days two and seven. Bilateral lungs were sectioned, stained and assessed for injury at day seven. Comparisons were performed in Graphpad with significance defined as ∗P <0.05.

RESULTS

Rats who underwent PT had significant weight loss and anemia at day 2 (P = 0.001) compared to naïve rats which persisted at day 7 (P = 0.001). PT rats had elevated plasma neutrophil gelatinase-associated lipocalin at day 2 compared to naïve (P <0.0001) which remained elevated at day 7 (P <0.0001). Plasma toll-like receptor 4 was elevated in PT compared to naïve at day 2 (P = 0.03) and day 7 (P = 0.01). Bilateral lungs showed significant injury in PT cohorts at day 7 compared to naïve (P <0.0004). PT males had worse renal function at day seven compared to females (P = 0.02).

CONCLUSIONS

Multicompartmental trauma induces systemic inflammation and multiorgan dysfunction without recovery by day seven. However, females demonstrate improved renal recovery compared to males. Long-term assessment of preclinical PT models are crucial to better understand and evaluate future therapeutic immunomodulatory and anti-inflammatory treatments.

Gut barrier protein levels in serial blood samples from critically ill trauma patients during and after intensive care unit stay

PURPOSE

In an effort to better manage critically ill patients hospitalised in the intensive care unit (ICU) after experiencing multiple traumas, the present study aimed to assess whether plasma levels of intestinal epithelial cell barrier proteins, including occludin, claudin-1, junctional adhesion molecule (JAM-1), tricellulin and zonulin, could be used as novel biomarkers. Additional potential markers such as intestinal fatty acid-binding protein (I-FABP), D-lactate, lipopolysaccharide (LPS) and citrulline were also evaluated. We also aimed to determine the possible relationships between the clinical, laboratory, and nutritional status of patients and the measured marker levels.

METHODS

Plasma samples from 29 patients (first, second, fifth and tenth days in the ICU and on days 7, 30 and 60 after hospital discharge) and 23 controls were subjected to commercial enzyme-linked immunosorbent assay (ELISA) testing.

RESULTS

On first day (admission) and on the second day, plasma I-FABP, D-lactate, citrulline, occludin, claudin-1, tricellulin and zonulin levels were high in trauma patients and positively correlated with lactate, C-reactive protein (CRP), number of days of ICU hospitalisation, Acute Physiology and Chronic Health Evaluation II (APACHE II) score and daily Sequential Organ Failure Assessment (SOFA) scores (P < 0.05-P < 0.01).

CONCLUSION

The results of the present study showed that occludin, claudin-1, tricellulin and zonulin proteins, as well as I-FABP, D-lactate and citrulline, may be used as promising biomarkers for the evaluation of disease severity in critically ill trauma patients, despite the complexity of the analysis of various barrier markers. However, our results should be supported by future studies.

Impact of the Junction Adhesion Molecule-A on Asthma

PURPOSE

Junctional adhesion molecule (JAM)-A is an immunoglobulin-like molecule that colocalizes with tight junctions (TJs) in the endothelium and epithelium. It is also found in blood leukocytes and platelets. The biological significance of JAM-A in asthma, as well as its clinical potential as a therapeutic target, are not well understood. The aim of this study was to elucidate the role of JAM-A in a mouse model of asthma, and to determine blood levels of JAM-A in asthmatic patients.

MATERIALS AND METHODS

Mice sensitized and challenged with ovalbumin (OVA) or saline were used to investigate the role of JAM-A in the pathogenesis of bronchial asthma. In addition, JAM-A levels were measured in the plasma of asthmatic patients and healthy controls. The relationships between JAM-A and clinical variables in patients with asthma were also examined.

RESULTS

Plasma JAM-A levels were higher in asthma patients (n=19) than in healthy controls (n=12). In asthma patients, the JAM-A levels correlated with forced expiratory volume in 1 second (FEV₁%), FEV₁/forced vital capacity (FVC), and the blood lymphocyte proportion. JAM-A, phospho-JNK, and phospho-ERK protein expressions in lung tissue were significantly higher in OVA/OVA mice than in control mice. In human bronchial epithelial cells treated with house dust mite extracts for 4 h, 8 h, and 24 h, the JAM-A, phospho-JNK, and phospho-ERK expressions were increased, as shown by Western blotting, while the transepithelial electrical resistance was reduced.

CONCLUSION

These results suggest that JAM-A is involved in the pathogenesis of asthma, and may be a marker for asthma.

Recent Developments in Mouse Trauma Research Models: A Mini-Review

The urgency to investigate trauma in a controlled and reproducible environment rises since multiple trauma still account for the most deaths for people under the age of 45. The most common multiple trauma include head as well as blunt thorax trauma along with fractures. However, these trauma remain difficult to treat, partially because the molecular mechanisms that trigger the immediate immune response are not fully elucidated. To illuminate these mechanisms, investigators have used animal models, primarily mice as research subjects. This mini review aims to 1) emphasize the importance of the development of clinically relevant murine trauma research, 2) highlight and discuss the existing conflict between simulating clinically relevant situations and elucidating molecular mechanisms, 3) describe the advantages and disadvantages of established mouse trauma models developed to simulate clinically relevant situations, 4) summarize and list established mouse models in the field of trauma research developed to simulate clinically relevant situations.

Therapeutic Potential of Mesenchymal Stromal Cell-Derived Extracellular Vesicles in the Prevention of Organ Injuries Induced by Traumatic Hemorrhagic Shock

Severe trauma is the principal cause of death among young people worldwide. Hemorrhagic shock is the leading cause of death after severe trauma. Traumatic hemorrhagic shock (THS) is a complex phenomenon associating an absolute hypovolemia secondary to a sudden and significant extravascular blood loss, tissue injury, and, eventually, hypoxemia. These phenomena are responsible of secondary injuries such as coagulopathy, endotheliopathy, microcirculation failure, inflammation, and immune activation. Collectively, these dysfunctions lead to secondary organ failures and multi-organ failure (MOF). The development of MOF after severe trauma is one of the leading causes of morbidity and mortality, where immunological dysfunction plays a central role. Damage-associated molecular patterns induce an early and exaggerated activation of innate immunity and a suppression of adaptive immunity. Severe complications are associated with a prolonged and dysregulated immune–inflammatory state. The current challenge in the management of THS patients is preventing organ injury, which currently has no etiological treatment available. Modulating the immune response is a potential therapeutic strategy for preventing the complications of THS. Mesenchymal stromal cells (MSCs) are multipotent cells found in a large number of adult tissues and used in clinical practice as therapeutic agents for immunomodulation and tissue repair. There is growing evidence that their efficiency is mainly attributed to the secretion of a wide range of bioactive molecules and extracellular vesicles (EVs). Indeed, different experimental studies revealed that MSC-derived EVs (MSC-EVs) could modulate local and systemic deleterious immune response. Therefore, these new cell-free therapeutic products, easily stored and available immediately, represent a tremendous opportunity in the emergency context of shock. In this review, the pathophysiological environment of THS and, in particular, the crosstalk between the immune system and organ function are described. The potential therapeutic benefits of MSCs or their EVs in treating THS are discussed based on the current knowledge. Understanding the key mechanisms of immune deregulation leading to organ damage is a crucial element in order to optimize the preparation of EVs and potentiate their therapeutic effect.

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.

Humoral Factors From Musculoskeletal Polytrauma Patients Impair Antibacterial Responses Of Neutrophils In vitro

Polytrauma is associated with increased risk of sepsis, but the risk for implant infection is less clear. Neutrophil antibacterial responses are significantly reduced in polytrauma patients (n= 9, ISS≥15) for at least 5 days compared to healthy controls. Reduced neutrophil activity could influence implant infection in addition to sepsis.

Modeling trauma in rats: similarities to humans and potential pitfalls to consider

Trauma is the leading cause of mortality in humans below the age of 40. Patients injured by accidents frequently suffer severe multiple trauma, which is life-threatening and leads to death in many cases. In multiply injured patients, thoracic trauma constitutes the third most common cause of mortality after abdominal injury and head trauma. Furthermore, 40-50% of all trauma-related deaths within the first 48 h after hospital admission result from uncontrolled hemorrhage. Physical trauma and hemorrhage are frequently associated with complex pathophysiological and immunological responses. To develop a greater understanding of the mechanisms of single and/or multiple trauma, reliable and reproducible animal models, fulfilling the ethical 3 R's criteria (Replacement, Reduction and Refinement), established by Russell and Burch in 'The Principles of Human Experimental Technique' (published 1959), are required. These should reflect both the complex pathophysiological and the immunological alterations induced by trauma, with the objective to translate the findings to the human situation, providing new clinical treatment approaches for patients affected by severe trauma. Small animal models are the most frequently used in trauma research. Rattus norvegicus was the first mammalian species domesticated for scientific research, dating back to 1830. To date, there exist numerous well-established procedures to mimic different forms of injury patterns in rats, animals that are uncomplicated in handling and housing. Nevertheless, there are some physiological and genetic differences between humans and rats, which should be carefully considered when rats are chosen as a model organism. The aim of this review is to illustrate the advantages as well as the disadvantages of rat models, which should be considered in trauma research when selecting an appropriate in vivo model. Being the most common and important models in trauma research, this review focuses on hemorrhagic shock, blunt chest trauma, bone fracture, skin and soft-tissue trauma, burns, traumatic brain injury and polytrauma.

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.

Tight junction structure, function, and assessment in the critically ill: a systematic review

BACKGROUND

Epithelial and endothelial barrier integrity, essential for homeostasis, is maintained by cellular boarder structures known as tight junctions (TJs). In critical illness, TJs may become disrupted, resulting in barrier dysfunction manifesting as capillary leak, pulmonary edema, gut bacterial translocation, and multiple organ failure. We aim to provide a clinically focused overview of TJ structure and function and systematically review and analyze all studies assessing markers of endothelial and epithelial TJ breakdown correlated with clinical outcomes in critically ill humans.

METHODS

We systematically searched MEDLINE, EMBASE, and PubMed. Additional articles were identified by targeted searches. We included studies that looked at the relationship between biomarkers of endothelial or epithelial TJ structure or function and critical illness. Results were qualitatively analyzed due to sample size and heterogeneity.

RESULTS

A total of 5297 abstracts met search criteria, of which 150 articles met requirements for full text review. Of these, 30 studies met inclusion criteria. Fifteen of the 30 reports investigated proteins of endothelial tight junctions and 15 investigated epithelial TJ markers, exclusively in the gastrointestinal epithelium. No studies investigated TJ-derived proteins in primary cardiac or pulmonary pathology.

CONCLUSIONS

TJ integrity is essential for homeostasis. We identified multiple studies that indicate TJs are disrupted by critical illness. These studies highlight the significance of barrier disruption across many critical disease states and correlate TJ-associated markers to clinically relevant outcomes. Further study on the role of multiple tissue-specific claudins, particularly in the setting of respiratory or cardiac failure, may lead to diagnostic and therapeutic advances.

SYSTEMATIC REVIEW REGISTRATION

This systematic review is registered in the PROSPERO database: CRD42017074546 .

Organ-Specific Differences in Endothelial Permeability-Regulating Molecular Responses in Mouse and Human Sepsis

In patients with sepsis-induced multi-organ dysfunction syndrome, diverging patterns of oedema formation and loss of function in organs such as lung and kidney suggest that endothelial permeability-regulating molecular responses are differentially regulated. This potential differential regulation has been insufficiently studied at the level of components of adherens and tight junctions. We hypothesized that such a regulation by endothelial cells in sepsis takes place in an organ-specific manner. We addressed our hypothesis by studying by quantitative real time polymerase chain reaction the expression of a predefined subset of EC permeability-related molecules (occludin, claudin-5, PV-1, CD-31, endomucin, Angiopoietin-1, Angiopoietin-2, Tie2, VEGFA, VEGFR1, VEGFR2, and VE-cadherin) in kidney and lung after systemic lipopolysacharide injection in mice, and in kidneys of patients who died of sepsis. We showed that baseline endothelial expression of permeability-related molecules differs in mouse kidney and lung. Moreover, we showed differential regulation of these molecules after lipopolysacharide injection in the two mouse organs. In lung we found a decrease in expression levels of molecules of the adherence and tight junctions complex and related signaling systems, compatible with increased permeability. In contrast, in kidney we found expression patterns of these molecules compatible with decreased permeability. Finally, we partially corroborated our findings in mouse kidney in human kidneys from septic patients. These findings may help to understand the clinical difference in the extent of oedema formation in kidney and lung in sepsis-associated organ failure.

Innate immune responses to trauma

Trauma can affect any individual at any location and at any time over a lifespan. The disruption of macrobarriers and microbarriers induces instant activation of innate immunity. The subsequent complex response, designed to limit further damage and induce healing, also represents a major driver of complications and fatal outcome after injury. This Review aims to provide basic concepts about the posttraumatic response and is focused on the interactive events of innate immunity at frequent sites of injury: the endothelium at large, and sites within the lungs, inside and outside the brain and at the gut barrier.

Mesenchymal Stem Cells after Polytrauma: Actor and Target

Mesenchymal stem cells (MSCs) are multipotent cells that are considered indispensable in regeneration processes after tissue trauma. MSCs are recruited to damaged areas via several chemoattractant pathways where they function as “actors” in the healing process by the secretion of manifold pro- and anti-inflammatory, antimicrobial, pro- and anticoagulatory, and trophic/angiogenic factors, but also by proliferation and differentiation into the required cells. On the other hand, MSCs represent “targets” during the pathophysiological conditions after severe trauma, when excessively generated inflammatory mediators, complement activation factors, and damage- and pathogen-associated molecular patterns challenge MSCs and alter their functionality. This in turn leads to complement opsonization, lysis, clearance by macrophages, and reduced migratory and regenerative abilities which culminate in impaired tissue repair. We summarize relevant cellular and signaling mechanisms and provide an up-to-date overview about promising future therapeutic MSC strategies in the context of severe tissue trauma.