Time course of the early pituitary-adrenal and metabolic responses to accidental injury

Identification of a miRNA signature in neutrophils after traumatic injury

Traumatic injury is the cause of significant mortality and morbidity. The molecular mechanisms underlying traumatic injury logically involve changes in gene expression that may be regulated through microRNAs (miRNAs). However, the association between miRNA deregulation and traumatic injury is largely unknown. The purpose of the present study is to address this issue. In this study, we used microarray profiling to evaluate the differential expressions of miRNAs in neutrophils obtained from patients with major trauma (injury severity scores >16), relative to healthy individuals. This neutrophilic miRNA signature was further validated using quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR). Genes and signaling pathways related to trauma-induced deregulated miRNAs were investigated in silico using the ontology-based and network mapping algorithms of Gene Ontology and Kyoto Encyclopedia of Genes or Genomes. Results showed that 13 miRNAs in neutrophils of major trauma patients were significantly and differentially expressed compared with the miRNA profiles of healthy controls. The results of qRT-PCR and in silico analysis revealed that miR-23a-5p, miR-30e-3p, miR-223-5p, miR-3945, miR-155-5p, and miR-150-5p were likely participants in the traumatic pathogenesis of these patients. In conclusion, neutrophils associated with traumatic injury were found to have a unique miRNA signature. Changes in signaling pathways due to deregulated miRNAs may be involved in the pathological processes of traumatic injury.

Immunomodulation in transfused trauma patients

PURPOSE OF REVIEW

Traumatic injury is a major human health problem, with many injured people supported by transfusion of allogeneic blood. Although trauma and transfusion have both been known to have immunomodulatory effects for some time, little is known about their combined effects or the scope and kinetics of such responses.

RECENT FINDINGS

Traumatic injury has a profound immunomodulatory effect on the patient, affecting a broad array of immunological components. This can be further complicated by transfusion, though the contribution of transfusion relative to the massive response triggered by trauma is small. The response to trauma involves a strong immunosuppressive component, which, contrary to the systemic inflammatory response syndrome/compensatory anti-inflammatory response syndrome model, occurs at the earliest time points examined and overlaps with proinflammatory and antimicrobial elements. This response is remarkably similar in a wide range of patients with different types and severities of injury.

SUMMARY

The response to trauma and transfusion involves a massive and rapid reorganization of the immune system that can put the patient at increased risk of infection, tissue damage, and organ failure. The scope of the response presents challenges to the development of treatments to control this dysregulation.

Transfusion-associated microchimerism: the hybrid within

Microchimerism, the coexistence of genetically disparate populations of cells in a receptive host, is well described in both clinical and physiological settings, including transplantation and pregnancy. Microchimerism can also occur after allogeneic blood transfusion in traumatically injured patients, where donor cells have been observed decades after transfusion. To date, transfusion-associated microchimerism (TA-MC) appears confined to this clinical subset, most likely due to the immune perturbations that occur after severe trauma that allow foreign donor cells to survive. Transfusion-associated microchimerism appears to be unaffected by leukoreduction and has been documented after transfusion with an array of blood products. The only significant predictor of TA-MC to date is the age of red cells, with fresher units associated with higher risk. Thus far, no adverse clinical effect has been observed in limited studies of TA-MC. There are, however, hypothesized links to transfusion-associated graft vs host disease that may be unrecognized and consequently underreported. Microchimerism in other settings has gained increasing attention owing to a plausible link to autoimmune diseases, as well as its diagnostic and therapeutic potential vis-a-vis antenatal testing and adoptive immunotherapy, respectively. Furthermore, microchimerism provides a tool to further our understanding of immune tolerance and regulation.

Androstenetriol improves survival in a rodent model of traumatic shock

Trauma results in activation of the hypothalamic-pituitary-adrenal axis to mediate a cascade of neurohormonal changes as a defensive mechanism. Its prolongation, however, leads to a hypermetabolic, hypoperfused, and immunosuppressed state, setting the stage for subsequent sepsis and organ failure. Androstenetriol (5-androstene-3beta, 7beta, 17betatriol - AET), a metabolite of dehydroepiandrosterone, up-regulates the host immune response markedly, prevents immune suppression and controls inflammation, leading to improved survival after lethal infections by several diverse pathogens and lethal radiation. Such actions may be useful in improving survival from traumatic shock.

HYPOTHESIS

The neurosteroid AET will increase survival following traumatic shock.

METHODS

A combat relevant model of traumatic shock was used. Male Sprague-Dawley rats were anesthetized, catheterized and subjected to soft tissue injury (laparotomy). Animals were allowed to regain consciousness over the next 0.5 h and then bled 40% of their blood volume over 15 min. Forty-five minutes after the onset of hemorrhage animals were randomized to receive either a single subcutaneous dose of AET (40 mg/kg, sc) or vehicle (methylcellulose). Volume resuscitation consisted of l-lactated Ringer's (three times the shed blood volume), followed by packed red blood cells (one-third shed red cell volume). Animals were observed for three days.

RESULTS

A total of 24 animals were studied. Of the 12 animals randomized to receive AET, all (100%) survived compared to 9 of 12 animals (75%) randomized to receive the vehicle (p < 0.05).

CONCLUSION

AET significantly improved survival when administered subcutaneously in a single dose in this rodent model of traumatic shock. Further survival and mechanism studies are warranted.

Relationship between serum glucose and injury severity score in childhood trauma

PURPOSE

The aim of this study was to examine the relationship between initial serum glucose and injury severity score (ISS) in children with multiple trauma.

METHODS

Charts from all patients 0 to 19 years of age admitted to a children's hospital in 1995 with acute multiple trauma were reviewed. Data collected included initial serum glucose level, heart rate (HR), systolic blood pressure (SBP), Injury Severity Score (ISS), age, gender, location of trauma, and need for intravenous fluids or epinephrine. Data were analyzed using multiple linear regression.

RESULTS

A total of 185 charts were reviewed. The mean ISS was 11.3; the mean glucose was 162.8 mg/dL. After adjusting for age, gender, HR, SBP, and administration of epinephrine or fluid bolus, a significant direct relationship between serum glucose and ISS was found (r = 0.52, P < .01). A stronger relationship was found in children less than 2 years old (r = 0.60, P = .04).

CONCLUSIONS

A significant direct relationship exists between glucose and ISS in children with multiple trauma. High glucose values may indicate more severe injury, especially in children less than 2 years old.

Do peripheral blood counts have any prognostic value following trauma?

BACKGROUND

Both lymphocytosis and lymphopenia have been observed following trauma and each has been claimed to predict mortality. An understanding of the early temporal changes in leucocyte counts may help to explain why such discrepancies have been found. The purpose of this study was to determine the early serial changes in peripheral leucocyte counts following injury.

METHODS

A whole blood cell counter was used to measure serial total leucocyte, granulocyte, lymphocyte and monocyte counts from 20 patients in the first 3 h following blunt injury. Four to six peripheral blood samples were taken from each subject and grouped into 20 min intervals.

RESULTS

Granulocytosis, lymphocytosis and monocytosis were evident within 40 min of injury. A biphasic granulocyte and monocyte response was observed in the first 3 h following trauma. Lymphocytes showed a linear resolution towards normal (regression coefficient -0.022; p < 0.01) with some individuals developing a lymphopenia. No correlation with injury severity was observed.

CONCLUSION

Rapid mobilisation and subsequent redistribution of leucocytes occurs early following injury. Temporal changes will affect any predictive value of circulating leucocytes and studies must be precise with respect to blood sampling time.

Stress and immunity after traumatic injury: the mind-body link

Traumatic injury poses a significant psychologic and physiologic threat, challenging a victim's perceptions of control over their environment and life outcomes. The multiple stressors presented by traumatic injury diminishes the patient's perceptions of control, resulting in a subjective stress response. Increased stress response after traumatic injury has been associated with altered immune function and decreased immunity. This paper reviews the current literature on stress and immunity after traumatic injury, focusing on the immune changes induced by excessive serum cortisol. It then presents evidence suggesting that the trauma patient's subjective stress response and diminished perceptions of control may act as factors in the immune changes occurring after injury. Recent studies supporting this hypothesis are reviewed, and recommendations for interventions, nursing practice, and research are discussed.