Early organ-specific hemorrhage-induced increases in tissue cytokine content: associated neurohormonal and opioid alterations

Association between Blood Glucose and cardiac Rhythms during pre-hospital care of Trauma Patients - a retrospective Analysis

Background

Deranged glucose metabolism is frequently observed in trauma patients after moderate to severe traumatic injury, but little data is available about pre-hospital blood glucose and its association with various cardiac rhythms and cardiac arrest following trauma.

Methods

We retrospectively investigated adult trauma patients treated by a nationwide helicopter emergency medical service (34 bases) between 2005 and 2013. All patients with recorded initial cardiac rhythms and blood glucose levels were enrolled. Blood glucose concentrations were categorised; descriptive and regression analyses were performed.

Results

In total, 18,879 patients were included, of whom 185 (1.0%) patients died on scene. Patients with tachycardia (≥100/min, 7.0 ± 2.4 mmol/L p < 0.0001), pulseless ventricular tachycardia (9.8 ± 1.8, mmol/L, p = 0.008) and those with ventricular fibrillation (9.0 ± 3.2 mmol/L, p < 0.0001) had significantly higher blood glucose concentrations than did patients with normal sinus rhythm between 61 and 99/min (6.7 ± 2.1 mmol/L). In patients with low (≤2.8 mmol/L, 7/79; 8.9%, p < 0.0001) and high (> 10.0 mmol/L, 70/1271; 5.5%, p < 0.0001) blood glucose concentrations cardiac arrest was more common than in normoglycaemic patients (166/9433, 1.8%). ROSC was more frequently achieved in hyperglycaemic (> 10 mmol/L; 47/69; 68.1%) than in hypoglycaemic (≤4.2 mmol/L; 13/31; 41.9%) trauma patients (p = 0.01).

Conclusions

In adult trauma patients, pre-hospital higher blood glucose levels were related to tachycardic and shockable rhythms. Cardiac arrest was more frequently observed in hypoglycaemic and hyperglycaemic pre-hospital trauma patients. The rate of ROSC rose significantly with rising blood glucose concentration. Blood glucose measurements in addition to common vital parameters (GCS, heart rate, blood pressure, breathing frequency) may help identify patients at risk for cardiopulmonary arrest and dysrhythmias.

Hemorrhage-induced interleukin-1 receptor pathway in lung is suppressed by 3,5-bis(2-fluorobenzylidene)-4-piperidone in a rat model of hypovolemic shock

Severe blood loss in victims of trauma creates an exaggerated inflammatory background that contributes to the development of intravascular coagulopathy and multiple organ dysfunction syndrome. We hypothesized that treatment with diphenyldifluoroketone EF24, an inhibitor of nuclear factor kappa-B, would have salutary effects in hemorrhagic shock. The objective of this study was to investigate the effect of EF24 on the expression of the interleukin-1 receptor (IL-1R) superfamily in a rat model of hypovolemic shock. Hypovolemia was induced by gradually withdrawing approximately 50% of circulating blood, and EF24 was administered intraperitoneally (0.2 mg/kg) in 50 μL of saline. After 6 h of shock, lung tissue was probed immunohistochemically and by immunoblotting to study the expression of Toll-like receptor 4 (TLR4), IL-1R, suppression of tumorigenicity 2 (ST2), and single immunoglobulin IL-1R-related (SIGIRR). The tissue-associated pro-inflammatory cytokines, tumor necrosis factor alpha (TNF-α) and IL-6, were measured by enzyme-linked immunosorbent assay. We observed a reduction in immunoreactive TLR4 and IL-1R1 in lung tissue of rats treated with EF24. Simultaneously, the pulmonary expression of ST2 and SIGIRR (the putative down-regulators of the pro-inflammatory IL-1R pathway) was increased in EF24-treated hemorrhaged rats. The concentration of hemorrhage-induced TNF-α and IL-6 in lung tissue homogenates was also reduced by EF24 treatment. These results confirm our previous in vitro observations in lipopolysaccharide-stimulated dendritic cells that EF24 beneficially modulates the IL-1R pathway and suggest that it could be investigated as an adjunct therapeutic in managing inflammation associated with hemorrhagic shock.

Targeted resuscitation improves coagulation and outcome

BACKGROUND

Acute trauma coagulopathy in seriously injured casualties may be initiated by tissue hypoperfusion. A targeted (or novel hybrid [NH]) resuscitation strategy was developed to overcome poor tissue oxygen delivery associated with prolonged hypotension.

METHODS

Under the Animals (Scientific Procedures) Act 1986, terminally anesthetized large white pigs were divided into four groups (n = 6). Groups 1 and 2 received blast injury and 3 and 4 no blast (sham). All were given a controlled hemorrhage (35% blood volume) and an uncompressed grade IV liver injury. Five minutes later, all were resuscitated with 0.9% saline to a systolic arterial pressure (SAP) of 80 mm Hg. After 60 minutes, the NH groups (1 and 3) were resuscitated to a SAP (110 mm Hg), whereas hypotensive groups (2 and 4) continued with SAP 80 mm Hg for up to 8 hours from onset of resuscitation.

RESULTS

Mean survival time was shorter in group 2 (258 minutes) compared with groups 1, 3, and 4 (452 minutes, 448 minutes, and 369 minutes). By the end of the study, hypotension was associated with a significantly greater prothrombin time (1.73 ± 0.10 and 1.87 ± 0.15 times presurgery, groups 2 and 4) compared with NH (1.44 ± 0.09 and 1.36 ± 0.06, groups 1 and 3, p = 0.001). Blast versus sham had no significant effect on prothrombin time (p = 0.56). Peak levels of interleukin 6 were significantly lower in NH groups. Arterial base excess was significantly lower with hypotension (-18.4 mmol/L ± 2.7 mmol/L and -12.1 mmol/L ± 3.2 mmol/L) versus NH (-3.7 mmol/L ± 2.8 mmol/L and -1.8 mmol/L ± 1.8 mmol/L, p = 0.0001). Hematocrit was not significantly different between groups (p = 0.16).

CONCLUSION

Targeted resuscitation (NH) attenuates the development of acute trauma coagulopathy and systemic inflammation with improved tissue perfusion and reduced metabolic acidosis in a model of complex injury. This emphasizes the challenge of choosing a resuscitation strategy for trauma patients where the needs of tissue perfusion must be balanced against the risk of rebleeding during resuscitation.

Central acetylcholinesterase inhibition improves hemodynamic counterregulation to severe blood loss in alcohol-intoxicated rats

Acute alcohol intoxication results in impaired hemodynamic counterregulation to blood loss and is associated with an attenuated hemorrhage-induced release of catecholamines and AVP. We speculated that restoration of the neuroendocrine response to hemorrhage would improve mean arterial blood pressure (MABP) recovery during acute alcohol intoxication. Previously, we demonstrated that intracerebroventricular (i.c.v.) choline, a precursor of acetylcholine, transiently increases sympathetic nervous system (SNS) outflow but is not capable of improving neuroendocrine and hemodynamic compensation to hemorrhage in alcohol-treated rats. We hypothesized that prolongation of the observed effect via i.c.v. neostigmine, an acetylcholinesterase inhibitor, would enhance SNS outflow, restore the neuroendocrine response, and in turn improve hemodynamic responses to hemorrhage during acute alcohol intoxication. I.c.v. neostigmine (1 microg) increased MABP, catecholamines, and AVP within 5 min and reversed hypotension due to 40% hemorrhage and intragastric alcohol (30% wt/vol, 2.5 g/kg) administration in chronically catheterized male Sprague-Dawley rats (225-250 g body wt). Acute alcohol intoxication before 50% hemorrhage decreased basal MABP, accentuated hypotension midhemorrhage, suppressed the hemorrhage-induced release of norepinephrine and AVP, and prevented restoration of MABP to basal levels after fluid resuscitation with lactated Ringer solution. I.c.v. neostigmine (0.5 microg) produced a sustained increase in MABP beginning at 30 min of hemorrhage that persisted throughout fluid resuscitation in control and alcohol-treated animals. I.c.v. neostigmine enhanced epinephrine responses and restored the hemorrhage-induced release of norepinephrine and AVP in alcohol-treated rats. These results demonstrate that inhibition of acetylcholinesterase in the central nervous system enhances SNS outflow, restores the neuroendocrine response to severe blood loss, and thereby improves hemodynamic counterregulation during acute alcohol intoxication. This study provides evidence for a central (and not peripheral) role of alcohol in impairing hemodynamic stability during hemorrhagic shock.

TLR4 is essential in acute lung injury induced by unresuscitated hemorrhagic shock

BACKGROUND

Acute lung injury (ALI) and acute respiratory distress syndrome in patients with hemorrhagic shock (HS) or resuscitation is associated with the expression of TLR4. However, the role of TLR4 in ALI induced by unresuscitated HS remains obscure.

METHODS

The lung pathologic change was observed by hematoxylin and eosin staining. Interleukin-1beta and tumor necrosis factor-alpha were analyzed by enzyme-linked immunosorbent assay. Polymorphonuclear leukocyte sequestration and lung leak were analyzed by pulmonary myeloperoxidase activity and Evans blue dye. The expressions of TLR4 mRNA and protein were analyzed by reverse transcription-polymerase chain reaction and Western blot, respectively. TLR4 distribution was analyzed by immunohistochemistry.

RESULTS

Lung neutrophil accumulation and microvascular permeability were significantly increased after unresuscitated HS, meanwhile, lung interleukin-1beta and tumor necrosis factor-alpha were gradually augmented. TLR4 mRNA, TLR4 distribution and TLR4 protein were also significantly increased in TLR4 wt mice, however, no above-mentioned changes appeared in TLR4 mutant mice.

CONCLUSIONS

TLR4 is strongly associated with the pathogenesis of ALI induced by unresuscitated HS, which may serve as a useful therapeutic target.

Effect of exogenous catecholamines on tumor necrosis factor alpha, interleukin-6, interleukin-10 and beta-endorphin levels following severe trauma

Cytokines and endogenous opioids are mediators of the post traumatic inflammatory response. The aim of this study was to determine the effect of exogenous catecholamines on tumor necrosis factor alpha (TNFa), interleukin-6 (IL-6), interleukin-10 (IL-10) and beta(beta)-endorphin levels in patients with severe trauma, during the first 24 h after injury. Forty four traumatized patients with haemorrhage class III and IV were included in the study. Patients were divided in two groups: Group 1 (adrenergic, n=22) and Group 2 (non adrenergic, n=22), depending on the use of exogenous catecholamines. Blood samples were collected at 0, 2, 4 and 24 h time points. Baseline values were different between the two groups, but an altered pattern of release was observed for TNFa, IL-6, IL-10 and beta-endorphin levels in patients treated with catecholamines. ICU stay was longer for the adrenergic group, while survival after 1 month was significantly lower. Findings support an altered pattern of cytokine release during the early phase after trauma, probably due to catecholamine presence.

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.

Fluid resuscitation increases inflammatory gene transcription after traumatic injury

BACKGROUND

The debate continues over type and quantity of fluid to administer for resuscitation after traumatic injury. This study aimed to examine effects of resuscitation with lactated Ringer's (LR) and Hextend (HEX) on the inflammatory response after uncontrolled hemorrhagic shock (UHS).

METHODS

There were 38 swine randomized. Control swine were anesthetized and killed. Sham swine underwent laparotomy, splenectomy, and 2 hours of anesthesia. UHS swine received a grade V liver injury after laparotomy and splenectomy and were randomized to no fluid (NF) resuscitation or to blinded resuscitation 30 minutes after injury with LR or HEX. Fluids were infused as needed to maintain baseline blood pressure for 90 minutes. Lung tissue mRNA levels of interleukin-6 (IL-6), granulocyte colony stimulating factor (G-CSF), and tumor necrosis factor alpha (TNF-alpha) were determined. Lung sections were examined for neutrophils (PMNs) sequestered within alveolar walls.

RESULTS

All UHS animals survived and initial blood loss was similar between groups. Mean arterial pressures (MAPs) were similar for all UHS animals until resuscitation was initiated. MAPs of resuscitated animals remained similar and were significantly higher than MAPs of the NF animals. Sequestered PMNs were equally elevated in all UHS animals. Cytokine analysis showed increased IL-6, G-CSF, and TNF-alpha gene transcription in resuscitated swine compared with NF swine. LR and HEX resuscitated swine tissue mRNA levels showed no differences.

CONCLUSIONS

Fluid resuscitation after solid organ injury and uncontrolled hemorrhage results in greater proinflammatory gene transcription than no resuscitation. LR and HEX resuscitation have equivalent effects on indices of inflammation in the lungs.

NEUROBIOLOGY OF THE STRESS RESPONSE: CONTRIBUTION OF THE SYMPATHETIC NERVOUS SYSTEM TO THE NEUROIMMUNE AXIS IN TRAUMATIC INJURY

Acute injury produces an immediate activation of neuroendocrine mechanisms aimed at restoring hemodynamic and metabolic counter-regulatory responses. These counter-regulatory responses are mediated by the systemic and tissue-localized release of neuroendocrine-signaling molecules known to affect immune function. This has led to the recognition of the importance of neuroendocrine-immune modulation during acute injury as well as throughout the recovery period. The period immediately after acute injury is characterized by upregulation of proinflammatory cytokine expression leading to a later period of generalized immunosuppression. The course and progression of the host recovery from traumatic injury and the integrity of its response to a secondary challenge is directly related to the effective control of the immediate proinflammatory responses to the initial insult. Among the neuroendocrine mechanisms involved in restoring homeostasis, the sympathetic nervous system plays a central role in mediating acute counter-regulatory stress responses to injury. In addition to its recognized cardiovascular, hemodynamic, and metabolic effects, the neurotransmitters released by the sympathetic nervous system have been shown to affect immune function through specific adrenergic receptor-mediated pathways. In turn, cells of the immune system and their products have been shown to influence peripheral and central neurotransmission, leading to the conceptualization of a bidirectional neuroimmune communication system. The reflex activation of this bidirectional neuroimmune pathway in response to injury, integrated with the parasympathetic nervous system, and opioid and glucocorticoid pathways responsible for orchestrating the counterregulatory stress response, results in dynamic regulation of host defense mechanisms vital for immune competence and tissue repair. This review provides the biological framework for the integration of our understanding of the neuroendocrine mechanisms involved in mediating the stress response and their role in modulating immune function during and after traumatic injury.

TSC for hemorrhagic shock: effects on cytokines and blood pressure

Previous studies have shown that administering trans-sodium crocetinate (TSC) as a treatment of hemorrhagic shock leads to increased whole-body oxygen consumption and survival as well as protection of the liver and kidney. It has been suggested that TSC increases oxygen delivery by increasing the diffusivity of oxygen through plasma. However, as with any novel mechanism of action, there are always questions about whether the results could also be ascribed to other, previously described mechanisms of action. This study was designed to look at some aspects of that by examining the effect of different TSC dosing regimens on the blood pressure and the production of cytokines after hemorrhage because both responses have been reported with compounds that act via other mechanisms. In a constant-pressure rat model of hemorrhagic shock, it was seen that a singe bolus injection of TSC results in an immediate but transient increase in the arterial blood pressure. This is similar to the effect reported previously for using 100% oxygen. It was also found that if the TSC injections were repeated periodically over an hour, a sustained increase in the blood pressure would occur. Because inflammatory cytokines have been implicated in mortality and tissue damage, it has been suggested that TSC may affect the production of cytokines. Thus, the effect of TSC on the production of TNF-alpha and IL-10 was also examined. The data show that treatment with TSC results in lower concentrations of TNF-alpha in the liver and spleen as well as lower concentrations of IL-10 in the spleen. Again, similar effects on other cytokines have been seen with 100% oxygen. These results support the hypothesis that the effects of TSC on hemorrhagic shock are mediated via an effect on oxygen.

Differential expression of extracellular matrix remodeling genes in rat model of hemorrhagic shock and resuscitation1,2

BACKGROUND

Matrix metalloproteinases (MMPs) and their specific physiological inhibitors, tissue inhibitors of metalloproteinases (TIMPs), are thought to play an essential role in tissue repair, cell death and morphogenesis. We have previously discovered unexpected up-regulation of genes coding for multiple MMP/TIMP family members in a rat model of hemorrhagic shock and resuscitation. However, the effect of different resuscitation protocols at the level of protein expression and function remains unknown.

MATERIALS AND METHODS

Male Sprague-Dawley rats (n = 50; 10/group) were subjected to a three-stage volume controlled hemorrhage and resuscitated as follows: 1) lactated Ringer's solution (LR), 3:1 volume of lost blood; 2) 7.5% hypertonic saline (HTS), 9.7 ml/kg; 3) plasma, 1:1 volume. Sham hemorrhage and sham resuscitation groups were used as controls. Expression of lung and spleen MMPs (-2, -7, -9, -10, -14, and -16), and TIMPs (-1, -2, and -3) was analyzed at transcriptional, functional and protein expression level using RT-PCR, ELISA, Western blotting, and gelatin zymography techniques.

RESULTS

Spleen was affected more than lung by the resuscitation strategy and the largest number of changes was caused by HTS resuscitation. RT-PCR confirmed an increased levels of MMP-2, MMP-9, MMP-7, MMP-14, MMP-16, and TIMP-1, TIMP-2 in the spleen of HTS group compared to sham groups, whereas in lungs transcriptional levels of only TIMP-3 and TIMP-1 were significantly changed.

CONCLUSION

Expression of MMP and TIMP in lung and spleen following hemorrhage is modulated by the resuscitation strategy.

Consequences of alcohol-induced early dysregulation of responses to trauma/hemorrhage

Acute alcohol intoxication is a frequent underlying condition associated with traumatic injury. Studies from our laboratory have been designed to examine the early hemodynamic, proinflammatory, and neuroendocrine alterations in responses to hemorrhagic shock in surgically catheterized, conscious, unrestrained, male Sprague-Dawley rats during acute alcohol intoxication (1.75-g/kg bolus, followed by a constant 15-h infusion at a rate of 250-300 mg/kg/h). With both fixed-pressure (40 mm Hg) and fixed-volume (50%) hemorrhagic shock, followed by fluid resuscitation with Ringer's lactate, acute (15 h) alcohol intoxication has been shown to impair significantly the immediate hemodynamic, metabolic, and inflammatory counterregulatory responses to hemorrhagic shock. Alcohol intoxication enhanced hemodynamic instability during blood loss and impaired the recovery of mean arterial blood pressure during fluid resuscitation. Activation of neuroendocrine pathways involved in restoring hemodynamic stability was significantly attenuated in alcohol-intoxicated hemorrhaged animals. The hemodynamic and neuroendocrine impairment is associated with enhanced expression of lung and spleen tumor necrosis factor, and it suppressed circulating neutrophil function. In addition, neuroimmune regulation of cytokine production by spleen-derived macrophages obtained from alcohol-intoxicated hemorrhaged animals was impaired when examined in vitro. We hypothesize that impaired neuroendocrine activation contributes to hemodynamic instability, which, in turn, prolongs tissue hypoperfusion and enhances risk for tissue injury. Specifically, the early dysregulation in counterregulatory responses is hypothesized to affect host defense mechanisms during the recovery period. We examined host response to systemic (cecal ligation and puncture) and localized (pneumonia) infectious challenge in animals recovering from hemorrhage during acute alcohol intoxication. Increased morbidity and mortality from infection were observed in alcohol-intoxicated hemorrhaged animals. Our results indicate that alcohol-induced alterations in early hemodynamic and neuroimmune responses to shock have an impact on susceptibility to an infectious challenge during the early recovery period.

HEMODYNAMIC AND IMMUNE CONSEQUENCES OF OPIATE ANALGESIA AFTER TRAUMA/HEMORRHAGE

The regulation of compensatory hemodynamic, inflammatory, and metabolic counter-regulatory responses to traumatic injury (trauma/hemorrhage [tx/hem]) and subsequent inflammatory challenges during the post-tx/hem period relies on balanced activation of neuroendocrine and opioid pathways. Pharmacological interventions during the rescue period as well as during the early post-tx/hem period that target these regulatory pathways can potentially affect the activation or efficacy of compensatory mechanisms. Their impact on mechanisms involved in these responses has not been well defined. We examined the impact of morphine and ketamine on immediate hemodynamic responses to tx/hem as well as on the integrity of host defense mechanisms at day 5 post-tx/hem. Morphine (10 mg/kg), ketamine (18 mg/kg), or saline (0.3 ml) were injected intraperitoneally at 15 min post-tx/hem (soft tissue injury and fixed pressure hemorrhage, 40 mmHg, 60 min) and 15 min before lactated Ringer's fluid resuscitation (LRFR, 2.4x total blood volume removed). Morphine, but not ketamine, produced effective and sustained analgesia. Morphine and ketamine impaired the rise in mean arterial blood pressure (MABP) during LRFR and increased 48-h mortality (2- to 3-fold). Morphine and ketamine markedly (40%-80%) attenuated the systemic LPS- (100 microg/100 g body weight) induced TNF response at day 5 post-tx/hem. Morphine attenuated LPS-induced lung and spleen TNF expression, whereas ketamine enhanced spleen TNF expression but did not alter lung responses. Subsequent studies demonstrated that the morphine-induced impairment of the response was not due to altered cytokine responses during the early post-tx/hem period but that they could be restored and 24 h mortality could be reduced by increasing the volume of LRFR (2-fold). These results indicate that morphine and ketamine analgesia compromise the hemodynamic and host defense responses after tx/hem, directly affecting mortality and morbidity during the recovery period.

Contribution of the adrenal glands and splenic nerve to LPS-induced splenic cytokine production in the rat

Both the hypothalamic pituitary adrenal axis (HPAA) and the sympathetic nervous system (SNS) can inhibit immune function and are regarded as the primary efferent pathways for neural-immune interactions. To determine if this relationship is maintained in vivo in response to an inflammatory stimulus, rats were injected intravenously (iv) with various doses of lipopolysaccharide (LPS) and splenic cytokine mRNA and protein levels were measured at several dose and time intervals post-injection. The spleen was chosen as the target organ because both the neural and hormonal inputs to the spleen can be selectively removed by splenic nerve cut (SNC) and adrenalectomy (ADX), respectively. Data from our dose response studies established that maximum levels of splenic cytokines were induced in response to relatively low doses of LPS. Minimal changes in LPS-induced splenic cytokine levels were observed in response to ADX, SNC, or a combination of the two procedures across several doses of LPS. These results suggest that there are aspects of immune regulation that are functionally removed from these central modulatory systems and that the counter-regulatory responses induced by LPS have minimal impact on the concurrent induction of cytokines by this inflammatory stimulus. The conceptual model of neural-immune regulation as an inhibitory feedback system, at least with regards to the early activational effects induced by an inflammatory stimulus, was not supported by these studies.

Endotoxin stimulates in vivo expression of inflammatory cytokines tumor necrosis factor alpha, interleukin-1beta, -6, and high-mobility-group protein-1 in skeletal muscle

The presence of increased levels of proinflammatory cytokines in the blood is associated with decreased muscle protein synthesis and the erosion of lean body mass in many catabolic conditions. However, little is known regarding the role of endogenous cytokine synthesis in muscle per se. The purpose of the present study was to characterize the cytokine expression profile of skeletal muscle in response to an in vivo injection of endotoxin (lipopolysaccharide, LPS). Intraperitoneal injection of a nonlethal dose of LPS (1,000 microg/kg Escherichia coli) into male rats increased the mRNA content of tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-1beta in gastrocnemius muscle as early as 1 h; IL-6 mRNA was not increased until 2 h post-LPS. Expression of TNF-alpha and IL-1beta peaked at 2 h (10- and 80-fold, respectively), whereas the increased IL-6 mRNA content (150-fold) peaked later at 4 h. The abundance of all measured cytokine mRNAs in skeletal muscle declined thereafter. The LPS-induced increase in muscle mRNA content for TNF-alpha, IL-6, and IL-1beta was dose-dependent with elevations being seen with as little as 10 microg/kg of LPS (2.5-, 8-, and 9-fold, respectively). In general, pretreatment of rats with dexamethasone attenuated but did not completely prevent the LPS-induced increase in muscle cytokine mRNA. LPS increased muscle TNF-alpha protein content approximately 2-fold and this increase was prevented by pretreatment with dexamethasone. LPS-induced increases in muscle IL-1beta and IL-6 protein were not detected. LPS also produced a 2-fold increase in the mRNA content of the high-mobility-group protein-1, a late-phase cytokine, in muscle at 12-24 h. Finally, although skeletal muscle was found to contain both the toll-like receptor (TLR)-2 and TLR4, LPS did not alter the mRNA content of TLR4 and produced a small (50%) but significant increase in TLR2 mRNA. These changes in TLRs were less dramatic than those observed for liver, spleen or cardiac muscle. Collectively these data indicate that skeletal muscle possesses many of the components of the innate immune system, including increases in both early- and late-phase cytokines and the presence of toll-like receptors.

Endogenous opioid analgesia in hemorrhagic shock

BACKGROUND

Hemorrhagic shock produces an immediate activation of the autonomic nervous system and endogenous opioid pathways. Our studies have demonstrated that endogenous opioid activation aggravates the hemodynamic and inflammatory responses to shock. However, it is unclear whether endogenous opioid activation is triggered by noxious stimuli and furthermore whether it produces analgesia.

METHODS

Experiments were conducted in chronically catheterized, conscious, unrestrained, nonheparinized, male, Sprague-Dawley rats subjected to fixed pressure hemorrhage. Blood samples were obtained for determinations of circulating beta-endorphin and substance P. Analgesia was measured using the tail-flick response to a noxious stimulus before and during hemorrhage. The contribution of sensory neurons to eliciting the neuroendocrine, opioid, and inflammatory responses to hemorrhage was investigated in capsaicin-treated animals.

RESULTS

Hemorrhagic shock produced marked naltrexone-sensitive analgesia without significant modulation of substance P. Peripheral sensory denervation did not alter the hemodynamic, neuroendocrine, or inflammatory responses to shock.

CONCLUSION

Endogenous opioid activation during shock produces analgesia. Sensory neuron activation appears to have limited effect on shock-induced hemodynamic and proinflammatory responses. Furthermore, these results suggest that the activation of neuroendocrine and opioid pathways during shock is not likely to be a response to noxious stimuli.

Effects of crystalloid and colloid resuscitation on hemorrhage-induced vascular hyporesponsiveness to norepinephrine in the rat

BACKGROUND

We have shown previously that hemorrhagic hypotension is associated with a progressive development of vascular hyporeactivity to norepinephrine (NE). The present study investigated whether select crystalloid or colloid resuscitation fluids would ameliorate this effect.

METHOD

Anesthetized male rats were hemorrhaged to and maintained at a mean arterial pressure (MAP) of 50 mm Hg for 60 minutes. Rats (n = 7 per group) were then resuscitated with lactated Ringer's (LR), 7.5% hypertonic saline (HS) for 1 hour followed by LR (HS-LR), Hespan, or Hextend to restore and maintain MAP to 70 mm Hg over 4 hours. Additional hemorrhaged groups were resuscitated with LR to the baseline MAP (LR-BL) or received no resuscitation. A sham hemorrhage group served as controls. The responses of MAP and the blood flow of the superior mesenteric, celiac, left renal, and left femoral arteries to NE (3 microg/kg administered intravenously) were measured at BL (prehemorrhage); at the end of the hypotensive period; and at 1, 2, and 4 hours after resuscitation.

RESULTS

Hemorrhagic hypotension significantly (p < 0.01) reduced the NE-induced pressor response in MAP and significantly reduced the contractile responses (reflected by the reduction of blood flow after NE administration) of the four arteries to NE. Hespan and Hextend infusion improved the NE response of MAP and the contractile responses of the observed arteries to NE significantly better than LR, HS-LR, or LR-BL. The colloids improved the vascular contractile responses to NE in the superior mesenteric and left femoral arteries and the pressor response of MAP to NE, to 80% to 90% of their basal response level compared with 40% to 60% with the crystalloid fluids (p < 0.05). LR-BL infusion resulted in hemodilution, with no added benefit to vascular responsiveness.

CONCLUSION

These data suggest that hypotensive resuscitation to 70 mm Hg with colloids was better than crystalloids in improving vascular responsiveness to the pressor effects of NE and required smaller volumes. Normotensive resuscitation with LR was not better than hypotensive resuscitation. Not all vasculatures improved equally after fluid resuscitation.

LVV-hemorphin-4 modulates Ca2+/calmodulin-dependent pathways in the immune system by the same mechanism as in the brain

The effect of synthetic LVV-hemorphin-4 (LVV-H4) on human blood and tonsils lymphocytes total phosphatase activity was studied by a spectrofluorimetric assay using 4-methylumbelliferyl phosphate (4-MUP) as a substrate. It has been established that LVV-H4 at concentrations of 10(-9) to 10(-7) M induces the inhibition of human blood (12-24%) and tonsils (42-45%) lymphocytes total phosphatase activity as 1 mM EGTA. The same peptide at concentrations of 10(-5) to 10(-4) M induces activation of human blood (48-57%) and tonsils (20-25%) lymphocytes total phosphatase activity. LVV-H4 is able to neutralize the inhibitory effect of calmodulin (CaM) antagonist and calcineurin inhibitor trifluoperazine (TFP) on human blood lymphocyte total phosphatase activity. It is suggested that a dose-dependent activation/inhibition of lymphocytes total phosphatase activity is due to activation/inhibition of lymphocyte calcineurin activity. Using enzyme-linked immunosorbentassay (ELISA) it was found that LVV-H4 neutralized the inhibitory effect of cyclosporin A (CsA) and TFP on interleukin-2 (IL-2) synthesis by activated blood lymphocytes. LVV-H4 also affects the lymphocytes proliferation, suppressed in pathophysiological condition, and restores their function by enhancement of DNA synthesis, as determined by measuring of [3H] thymidine incorporation into lymphocytes. It has been proposed that CaM is an essential component in starting up the molecular mechanism of hemorphins action and that calcineurin is a key enzyme underlying the molecular mechanism of hemorphins action on the brain and immune system.

Cytokine expression profiling in human leukocytes after exposure to hypertonic and isotonic fluids

BACKGROUND

Resuscitation from hemorrhagic shock causes profound immunologic changes. The tonicity of fluids used for resuscitation clearly influences the immune response. Our study was designed to determine whether isotonic and hypertonic fluids exert their differential effects on immune response by altering the cytokine gene profile of human leukocytes. The cDNA array method was used to profile transcriptional responses after exposure to hypertonic and isotonic fluids.

METHODS

Blood from seven healthy volunteers was incubated for 30 minutes with isotonic (10% dextran-40 and lactated Ringer's [LR] solution) and hypertonic (7.5% hypertonic saline and hypertonic dextran [HTD]) fluids. The volumes of isotonic fluids used were equal to the volume of blood, whereas the volumes of hypertonic fluids were adjusted to keep the salt load identical to the LR group. The cDNA array technique was used to measure the gene expression of 23 common cytokines.

RESULTS

Increased gene transcription of proinflammatory cytokines (interleukin [IL]-1alpha, IL-6, IL-10, and tumor necrosis factor-alpha) as well as others (IL-5, IL-7, and IL-16) was found after incubation with resuscitation fluids. Variances were noted depending on the type of fluid: HTD and LR solution did not induce expression of IL-5, and HTD also did not induce IL-1beta expression. Genes encoding IL-1alpha, IL-6, IL-9, and tumor necrosis factor-alpha had low level baseline expression in leukocytes isolated from unstimulated blood, and their expression increased markedly after exposure to resuscitation fluids. The inducible transcripts included IL-1beta, IL-7, IL-10, and IL-16. However, there was no difference in cytokine expression profile between isotonic and hypertonic fluids.

CONCLUSION

Exposure of human leukocytes to resuscitation fluids causes an increase in cytokine gene expressions compared with undiluted blood. This expression profile is largely independent of the type of fluid used.

Induction of early inflammatory gene expression in a murine model of nonresuscitated, fixed-volume hemorrhage

The etiology of many end-organ problems associated with hemorrhage has been attributed to the inflammatory response to hemorrhage. In a murine model of nonresuscitated, fixed-volume hemorrhage, we sought to elucidate the role that hemorrhagic insult alone plays in the generation of the early inflammatory cascade. Differences could be appreciated as early as 1 h post-hemorrhage, with consistent differences detected by 3 h in all of the major cytokine genes studied. Significant upregulation of IL-1beta , IL-6, TNF-alpha, and IL-10 mRNA expression was observed in both the liver and lung samples of mice subjected to fixed-volume hemorrhage when compared with sham-hemorrhaged mice. The cyclooxygenase-2 (COX-2) and inducible nitric oxide synthetase (iNOS) genes also were upregulated in the livers and lungs of hemorrhaged mice. Finally, expression of the genes that encode the Toll-like receptors (TLR)-2 and -4 was increased by hemorrhage. Taken collectively, these data demonstrate that the initial inflammatory cascade associated with hemorrhage occurs within hours after the initial hemorrhagic event, and can be associated with significant modulation of expression of key pro- and anti-inflammatory cytokine, enzyme, and TLR genes, suggesting that these may be possible new therapeutic targets.

Impact of alcohol intoxication on hemodynamic, metabolic, and cytokine responses to hemorrhagic shock

BACKGROUND

Alcohol intoxication is associated with a high incidence of traumatic injury, particularly in the young healthy population. The impact of alcohol intoxication on the immediate pathophysiologic response to injury has not been closely examined. We hypothesized that acute alcohol intoxication would aggravate the immediate outcome from hemorrhagic shock by impairing homeostatic counterregulation to blood loss.

METHODS

Chronically catheterized male Sprague-Dawley rats were randomized to receive an intragastric infusion of ethyl alcohol (1.75 g/kg followed by 250-300 mg/kg/h) or isocaloric dextrose (3-mL bolus + 0.375 mL/h) for 15 hours. Before initiating fixed-pressure hemorrhage followed by fluid resuscitation, an additional intragastric bolus of ethyl alcohol (1.75 g/kg) was administered. Hemodynamic, metabolic, cytokine, and acid-base parameters were assessed during the hemorrhage period and at completion of resuscitation. Lungs were obtained for cytokine determinations.

RESULTS

Basal mean arterial pressure was significantly lower in alcohol-intoxicated (blood-alcohol concentration, 135 +/- 12 mg/dL) animals than in controls during baseline (20%) and after the initial fluid resuscitation period (30%). Hemorrhage decreased arterial HCO3 and Pco2, and increased Po2 without significant alteration in arterial blood pH. Alcohol intoxication blunted the decrease in Pco2 and increase in Po2 and decreased blood pH during baseline and throughout the course of the hemorrhage period. Hemorrhage produced marked and progressive elevations in plasma glucose and lactate levels in controls, and this was inhibited by alcohol intoxication. Hemorrhage elevated plasma tumor necrosis factor-alpha (TNF-alpha) (686 +/- 252 pg/mL) and interleukin (IL)-10 (178 +/- 25 pg/mL), and did not alter IL-6 and IL-1 levels. Alcohol blunted the hemorrhage-induced rise in plasma TNF-alpha (142 +/- 48 pg/mL) and enhanced the hemorrhage-induced increase in IL-10 (678 +/- 187 pg/mL). Hemorrhage produced a two- to threefold increase in lung content of TNF-alpha, IL-1alpha, and IL-6 without significantly altering lung IL-10. Alcohol exacerbated the hemorrhage-induced increase in lung TNF-alpha, and did not alter the IL-1alpha, IL-6, and IL-10 lung responses.

CONCLUSION

These results indicate marked alterations in the hemodynamic and metabolic responses to hemorrhagic shock by alcohol intoxication. Furthermore, our findings suggest that alcohol modulates the early proinflammatory responses to hemorrhagic shock. Taken together, these alterations in metabolic and inflammatory responses to hemorrhage are likely to impair immediate outcome and predispose to tissue injury.

Stress-specific opioid modulation of haemodynamic counter-regulation

1. The haemodynamic and cardiovascular responses to stress, in addition to being under control of the autonomic nervous system, are also under opiate modulation. Our studies have provided evidence for activation of the endogenous opioid system in haemorrhagic shock, sepsis and trauma. Furthermore, we have demonstrated that both central and systemic opiate administration to naïve rats result in marked alterations in haemodynamic responses, which are associated with activation of the sympathetic nervous system. 2. Because of the ubiquitous presence of opiate receptors in both the central nervous system and peripheral tissues, as well as their production and release centrally and peripherally, this facilitates an endocrine as well as a paracrine contribution to modulating vascular responses to stress, either directly or indirectly. Results from previous studies suggest that endogenous opioids are not involved in mediating the lipopolysacharide-induced hypotensive response. 3. In more recent studies, we have examined the role of opiate receptor activation in modulating the haemodynamic and neuroendocrine responses to fixed pressure haemorrhagic shock in conscious unrestrained rats. Using systemic opiate blockade (naltrexone, 15 mg/kg, i.p.) prior to haemorrhage, we have observed that blood loss required to achieve mean arterial blood pressure of 40 mmHg was higher in naltrexone-treated animals than in time-matched saline controls. Interestingly, the haemodynamic modulation exerted by naltrexone cannot be attributed to differences in circulating catecholamine levels. Haemorrhage produced an immediate and progressive increase in circulating adrenaline and noradrenaline levels, reaching values that were 50- and 20-fold higher than basal, respectively. Naltrexone pretreatment did not alter the time-course or magnitude of the rise in circulating levels of catecholamines. 4. These results indicate that endogenous opioid activation contributes to the haemodynamic dishomeostasis associated with blood loss. Our findings suggest stress-specific roles for opiate-sensitive haemodynamic counter-regulatory responses.

Insulin resistance and glucose-induced thermogenesis in critical illness

Critical illness is associated with a marked increase in metabolic rate and progressive wasting, despite aggressive nutritional support. The metabolic events which are responsible for these phenomena are unclear, but are characterised by marked impairment of the anabolic effects of insulin on glucose metabolism and excessive activation of the sympathetic nervous system. It has been suggested that critical illness may be associated with impaired carbohydrate oxidation and a marked increase in the loss of heat energy associated with glucose administration (glucose-induced thermogenesis). This situation may result in impaired efficiency of nutrient assimilation. Studies employing combinations of nutrient infusions both at clinically-relevant rates and in association with euglycaemic hyperinsulinaemia have, however, demonstrated that nutrient-induced thermogenesis is unaffected in critical illness in human subjects, and that defective glucose utilization occurs as a consequence of impaired insulin-mediated glucose storage rather than oxidation. Although the cellular and molecular mechanisms underlying these changes are controversial, the recent validation of a human model of insulin resistance in critical illness should provide a means of studying this response in future, and allow the identification of therapeutic targets. This information should increase the efficacy of nutritional support in some of our most seriously-ill patients.

Differential effects of hemorrhage and LPS on tissue TNF-alpha, IL-1 and associate neuro-hormonal and opioid alterations

LPS administration and hemorrhage are frequently used models for the in vivo study of the stress response. Both challenges stimulate cytokine production as well as activate opiate and neuro-endocrine pathways; which in turn modulate the inflammatory process. Differences in the magnitude and tissue specificity of the proinflammatory cytokine and neuro-hormonal responses to these stressors are not well established. We contrasted the tissue specificity and magnitude of the increase in circulating and tissue cytokine (TNF-alpha, IL-1alpha and IL-1beta) content in response to either fixed-pressure hemorrhage (approximately 40 mm Hg) followed by fluid resuscitation (HEM) or lipopolysaccharide (LPS; 100 microg/100 g BW) administration. LPS and HEM elevated circulating levels of TNF-alpha, while neither stress altered circulating IL-1-alpha and IL-beta. LPS-induced increases in TNF-alpha content were greater than those elicited by HEM in all tissues studied except for the lung, where both stressors produced similar increases. Tissue (lung, spleen and heart) content of IL-1alpha was increased by HEM but was not affected by LPS. Tissue (lung, spleen, and heart) content of IL-1beta was increased by LPS but was not affected by HEM. HEM produced greater increases than LPS in epinephrine (16- vs. 4-fold) and norepinephrine (4-fold vs. 60%) levels and similar elevations in beta-endorphin. LPS produced greater elevation in corticosterone levels (2-fold) than HEM (50%). These results suggest differential tissue cytokine modulation to HEM and LPS, both with respect to target tissue and cytokine type. The hormonal milieu to HEM is characterized by marked catecholaminergic and moderate glucocorticoid while that of LPS is characterized by marked glucocorticoid with moderate catecholaminergic influence.

Effect of naloxone on immune responses after hemorrhagic shock

OBJECTIVE

To determine whether naloxone administration after hemorrhagic shock has any beneficial or deleterious effect on immune responses.

BACKGROUND DATA

Hemorrhagic shock is known to produce immunodepression in both humans and experimental animals. Although studies suggest that endogenous opioids play a role in immune regulation in adverse circulatory conditions, it remains controversial whether these opioids exert beneficial or detrimental effects on immunity after shock. Moreover, little information is available concerning the effects of opioid receptor blockade using naloxone on cell-mediated immunity and endocrine responses after shock.

METHODS

Male C3H/HeN mice (25 g) were bled to and maintained at a mean arterial blood pressure of 35+/-5 mm Hg for 1 hr. The shed blood was then returned along with lactated Ringer's solution (two times the shed blood volume) to provide fluid resuscitation. The animals were randomized to receive either naloxone (1 mg/kg i.v.) or an equal volume of vehicle (saline) after the shed blood was returned, i.e., immediately before crystalloid resuscitation, and were killed at 2 hrs after resuscitation to obtain splenocytes, macrophages (peritoneal and splenic), and blood.

MEASUREMENTS AND MAIN RESULTS

Bioassays revealed significantly decreased release of all studied interleukins (interleukins-1, -2, -3, and -6) by peritoneal and splenic macrophages as well as significantly decreased splenocyte proliferative capacity after shock in vehicle-treated mice. Naloxone administration after hemorrhage resulted in either similar or even more decreased levels of interleukin release compared with vehicle-treated hemorrhaged mice. Significantly increased plasma corticosterone concentrations were observed in vehicle-treated animals compared with control animals. Naloxone administration did not have any significant effects on corticosterone plasma concentrations after hemorrhage.

CONCLUSIONS

These findings indicate the importance of the endogenous opioid system for the maintenance of immunity in adverse circulatory conditions, i.e., hemorrhage. Although additional studies involving different doses and/or times of naloxone administration may provide different results, the present findings raise the concern that naloxone administration in the traumatized host may have deleterious effects because it decreases peritoneal macrophage and splenic immune functions.

Effects of beta-adrenergic blockade on hepatic and renal glucose production during hypoglycemia in conscious dogs

To investigate the role of beta-adrenergic mechanisms in the counterregulatory response of the liver and kidney to hypoglycemia, we studied 10 dogs before and after a 2-h constant infusion of insulin (4 mU. kg-1. min-1) either without (n = 4) or with (8 micrograms/min, n = 6) propranolol and variable dextrose to maintain hypoglycemia, 7 days after surgical placement of sampling catheters in left renal and hepatic veins and femoral artery. Systemic glucose appearance (Ra) and endogenous (EGP), hepatic (HGP), and renal (RGP) glucose production were measured by a combination of arteriovenous difference and peripheral infusion of [6-3H]glucose, renal blood flow with a flow probe, and hepatic plasma flow by indocyanine green clearance. Without beta-adrenergic blockade, arterial glucose decreased from 5.12 +/- 0.02 to 2.53 +/- 0.07 mmol/l, glucose Ra increased from 17.8 +/- 0.7 to 30.5 +/- 2.5 (P < 0.01) when EGP was 22.2 +/- 0.5, HGP from 13.5 +/- 1.1 to 19.3 +/- 1.3, and RGP from 2. 4 +/- 1.0 to 8.6 +/- 0.9 micromol. kg-1. min-1 (all P < 0.05). When propranolol was infused, glucose decreased from 5.97 +/- 0.02 to 2. 71 +/- 0.03 mmol/l, glucose Ra increased from 16.3 +/- 1.0 to 25.1 +/- 1.6 when EGP was 9.9 +/- 0.4, HGP decreased from 14.4 +/- 0.7 to 10.4 +/- 0.6, and RGP decreased from 3.8 +/- 1.3 to 1.1 +/- 0.8 micromol. kg-1. min-1 (all P < 0.05). Our data indicate that beta-adrenergic blockade impairs glucose recovery during sustained hypoglycemia, in part, by preventing the simultaneous compensatory increase in HGP and RGP.