Insight into the mechanism by which estradiol improves organ functions after trauma-hemorrhage

The beneficial roles and mechanisms of estrogens in immune health and infection disease

Multiple epidemiologic studies have revealed that gender is considered one of the important factors in the frequency and severity of certain infectious diseases, in which estrogens may play a vital role. There is growing evidence that estrogens as female sex hormone can modulate multiple biological functions outside of the reproductive system, such as in brain and cardiovascular system. However, it is largely unknown about the roles and mechanisms of estrogens/estrogen receptors in immune health and infection disease. Thence, by reading a lot of literature, we summarized the regulatory mechanisms of estrogens/estrogen receptors in immune cells and their roles in certain infectious diseases with gender differences. Therefore, estrogens may have therapeutic potentials to prevent and treat these infectious diseases, which needs further clinical investigation.

Estradiol provokes hypercoagulability and affects fibrin biology: A mechanistic exploration of sex dimorphisms in coagulation

BACKGROUND

Sex dimorphisms in coagulation are well established, with female-specific hypercoagulability conferring a survival benefit in the setting of trauma-induced coagulopathy (TIC). The mechanism behind these phenomena remains to be elucidated. We hypothesize that estradiol provokes a hypercoagulable profile and alters clot proteomics and fibrin crosslinking.

METHODS

Whole blood was collected from healthy adult volunteers (n = 30). A battery of thrombelastography (TEG) assays (native, kaolin, platelet-mapping, functional fibrinogen), whole blood thrombin generation, proteomics, and clot structure architecture (via analysis of fibrin crosslinks and fluorescent fibrinogen-visualized clots) were performed after pre-treatment of the blood with physiologic concentrations of beta-estradiol. In addition, a prospective study of coagulation through the menstrual cycle was conducted by collecting blood from women on peak and nadir estrogen days in the standard 28-day menstrual cycle.

RESULTS

On TEG, in females, estradiol provoked a hypercoagulable phenotype, specifically a shorter time to clot formation and greater thrombin generation, greater rate of clot propagation and functional fibrinogen, higher clot strength, and diminished clot fibrinolysis. In both males and females, estradiol increased platelet hyperactivity. Similar changes were seen in time to clot formation and clot strength in vivo during peak estrus of the menstrual cycle. On proteomic analysis, in both males and females, estradiol was associated with increases in abundance of several procoagulant and antifibrinolytic proteins. Crosslinking mass spectrometry analysis showed addition of estradiol increased the abundance of several FXIII crosslinks within the FIBA alpha chain in both sexes. Fluorescent fibrinogen analysis revealed a trend toward increased fiber resolvability index after addition of estradiol.

CONCLUSION

Estradiol provokes a hypercoagulable phenotype, affecting time to clot formation, clot propagation, clot strength, clot fibrinolysis, and clot structure. In sum, these data highlight the role of estradiol is driving female-specific hypercoagulability and highlights its potential role as a therapeutic adjunct in resuscitation of TIC.

Protective effects of 17β-oestradiol on coagulation and systemic inflammation after total occlusion of the descending aorta in male rats

OBJECTIVES

The surgical treatment for diseases of the descending aorta is related to a high mortality rate because of the activation of a systemic inflammatory process due to ischaemia and reperfusion (I/R) injury. Activation of coagulation can contribute to the inflammatory process, resulting in microcirculatory damage and multiple organ failure. Our goal was to evaluate the role of prophylactic intravenous 17β-oestradiol (E2) in coagulation, the inflammatory response and hepatic injury after occlusion of the descendent proximal aorta in male rats.

METHODS

Wistar male rats were randomized and allocated to 3 groups (n = 8 per group): sham, surgically manipulated; IR, animals subjected to I/R; and E2, animals treated with E2 (280 µg/kg, intravenously) before I/R. I/R was induced by insertion of a 2-Fr Fogarty arterial embolectomy catheter in the descending aorta, which was occluded for 20 min, followed by a reperfusion period of 2 h. Serological markers, platelet aggregation, hepatic vascular flow, systemic and liver inflammatory response and apoptosis were analysed. The coagulation process was evaluated by thromboelastometry.

RESULTS

The aortic occlusion led to a reduction in plasma fibrinogen concentration in parallel with increased clotting time, greater clot firmness and reduced lysis. E2 treatment was able to increase fibrinogen, prevent the increase in clotting time and normalize clot firmness, but it exerted only a mild effect on clot lysis. Platelet aggregation was increased by IR, and E2 treatment was able to reduce it. There was a reduction in flow percentage in the IR group that was not prevented by E2. In parallel, higher aggregate formation was observed in the vessels of the IR group of animals. There was increased systemic release of interleukin-1-β, interleukin-6 and interleukin-10 in the IR group, which was reduced in the treated animals.

CONCLUSIONS

The current results suggest that pretreatment with E2 before an ischaemic period induced by occlusion of the proximal descending aorta is effective in preventing alterations in coagulation and systemic inflammation due to I/R injury.

Regulation of c-Jun NH2-Terminal Kinase for Islet Transplantation

Islet transplantation has been demonstrated to provide superior glycemic control with reduced glucose lability and hypoglycemic events compared with standard insulin therapy. However, the insulin independence rate after islet transplantation from one donor pancreas has remained low. The low frequency of islet grafting is dependent on poor islet recovery from donors and early islet loss during the first hours following grafting. The reduction in islet mass during pancreas preservation, islet isolation, and islet transplantation leads to β-cell death by apoptosis and the prerecruitment of intracellular death signaling pathways, such as c-Jun NH₂-terminal kinase (JNK), which is one of the stress groups of mitogen-activated protein kinases (MAPKs). In this review, we show some of the most recent contributions to the advancement of knowledge of the JNK pathway and several possibilities for the treatment of diabetes using JNK inhibitors.

Sexual dimorphism in bacterial infections

Background

Sex differences are important epidemiological factors that impact in the frequency and severity of infectious diseases. A clear sexual dimorphism in bacterial infections has been reported in both humans and animal models. Nevertheless, the molecular mechanisms involved in this gender bias are just starting to be elucidated. In the present article, we aim to review the available data in the literature that report bacterial infections presenting a clear sexual dimorphism, without considering behavioral and social factors.

Main body

The sexual dimorphism in bacterial infections has been mainly attributed to the differential levels of sex hormones between males and females, as well as to genetic factors. In general, males are more susceptible to gastrointestinal and respiratory bacterial diseases and sepsis, while females are more susceptible to genitourinary tract bacterial infections. However, these incidences depend on the population evaluated, animal model and the bacterial species. Female protection against bacterial infections and the associated complications is assumed to be due to the pro-inflammatory effect of estradiol, while male susceptibility to those infections is associated with the testosterone-mediated immune suppression, probably via their specific receptors. Recent studies indicate that the protective effect of estradiol depends on the estrogen receptor subtype and the specific tissue compartment involved in the bacterial insult, suggesting that tissue-specific expression of particular sex steroid receptors contributes to the susceptibility to bacterial infections. Furthermore, this gender bias also depends on the effects of sex hormones on specific bacterial species. Finally, since a large number of genes related to immune functions are located on the X chromosome, X-linked mosaicism confers a highly polymorphic gene expression program that allows women to respond with a more expanded immune repertoire as compared with men.

Conclusion

Notwithstanding there is increasing evidence that confirms the sexual dimorphism in certain bacterial infections and the molecular mechanisms associated, further studies are required to clarify conflicting data and to determine the role of specific hormone receptors involved in the gender bias of bacterial infections, as well as their potential as therapeutic targets.

Sex-based differences in outcomes after severe injury: an analysis of blunt trauma patients in China

BACKGROUND

Experimental research suggests that females have a higher survival rate after trauma, although this claim is controversial. This study sought to determine the role of sex on mortality among trauma patients in China.

METHODS

The study enrolled 1789 trauma patients who visited the Emergency Intensive Care Unit of the First Affiliated Hospital of Zhengzhou University during 2015 and 2016. A retrospective data analysis was performed to determine sex-based differences after blunt trauma. Patients were stratified by age and injury severity (using the Injury Severity Score). Multiple logistic regression was used to analyze the association between sex and post-injury complications and mortality.

RESULTS

Female trauma patients experienced a significantly lower risk of mortality than males (odds ratio, 0.931; 95% confidence interval, 0.883-0.982). This survival advantage of females was particularly notable in the 'younger than 45 years' age group. Sex-based differences were also found in the occurrence of life-threatening complications after trauma.

CONCLUSION

This study demonstrated that females are more likely to survival after severe blunt trauma and also have less inpatient complications than men, suggesting an important role for sex hormones after severe traumatic injury.

Characterization of sex dimorphism following severe thermal injury

Sex-based outcome differences have been previously studied after thermal injury, with a higher risk of mortality being demonstrated in women. This is opposite to what has been found after traumatic injury. Little is known about the mechanisms and time course of these sex outcome differences after burn injury. A secondary analysis was performed using data from a prospective observational study designed to characterize the genetic and inflammatory response after significant thermal injury (2003-2010). Clinical outcomes were compared across sex (female vs male), and the independent risks associated with sex were determined using logistic regression analysis after controlling for important confounders. Stratified analysis across age and burn severity was performed, whereas Cox hazard survival curves were constructed to determine the time course of any sex differences found. During the time period of the study, 548 patients met inclusion criteria for the cohort study. Men and women were found to be similar in age, TBSA%, inhalation injury, and Acute Physiology and Chronic Health score. Regression analysis revealed that female sex was independently associated with over a 2-fold higher mortality after controlling for important confounders (odds ratio, 2.2; P = .049; 95% confidence interval, 1.01-4.8). The higher independent mortality risk for women was exaggerated and remained significant only in pediatric patients and demonstrated a dose-response relationship with increasing burn size (%TBSA). Survival analysis demonstrated early separation of female and male curves, and a greater independent risk of multiple organ failure was demonstrated in the pediatric cohort. The current results suggest that sex-based outcome differences may be different after thermal injury compared with traumatic injury and that the sex dimorphism may be exaggerated in patients with higher burn size and in those in the pediatric age group, with female sex being associated with poor outcome. These sex-based mortality differences occur early and may be a result of a higher risk of organ failure and early differences in the inflammatory response after burn injury. Further investigation is required to thoroughly characterize the mechanisms responsible for these divergent outcomes.

The influence of sex on outcomes in trauma patients: a meta-analysis

BACKGROUND

This study aims to assess the influence of sex on outcomes among trauma patients, including injury severity, medical resource utility, complications, and mortality.

METHODS

A systematic review of the literature was conducted by internet search. Data were extracted from selected studies and analyzed using Stata to compare outcomes between male and female injured patients.

RESULTS

Eventually, 19 studies met our inclusion criteria with 100,566 men and 39,762 women. Pooled data revealed that male sex was associated with increased risk of mortality, hospital length of stay, and higher incidence of complications. No difference was detected in injury severity between male and female patients.

CONCLUSION

Evidence of this meta-analysis strongly supports the sex dimorphism in the prognosis of trauma patients and further work should be done to decipher potential mechanism.

The early evolving sex hormone environment is associated with significant outcome and inflammatory response differences after injury

BACKGROUND

Clinical research characterizing the mechanisms responsible for sex-based outcome differences after injury remains conflicting. Currently lacking is an understanding of the early sex hormone milieu of the injured patient and the effects these early hormone differences have on clinical outcomes and the innate immune response following injury.

METHODS

A prospective cohort study was performed over a 20-month period. Blunt injury patients requiring intensive care unit admission were enrolled. Samples were collected within 6 hours and at 24 hours after injury and were analyzed for total testosterone (TT) and estradiol concentrations. Outcomes of interest included multiple-organ failure (MOF; Marshall Multiple Organ Dysfunction Score [MODScore] > 5), nosocomial infection (NI), mortality, and serial cytokine/chemokine measurements. Multivariate logistic regression was used to determine the independent risks associated with early sex hormone measurements.

RESULTS

In 288 prospectively enrolled patients, 69% were male, with a median Injury Severity Score (ISS) of 16 (interquartile range 10-21). Elevated TT levels at 6 hours were associated with elevated interleukin 6 levels and cytokine/chemokine measurements (18 of 24 measured). Rising TT levels were significantly associated with more than a fivefold and twofold higher independent risk of MOF and NI, respectively (odds ratio [OR], 5.2; p = 0.02; 95% confidence interval [CI], 1.2-22.3; and OR, 2.1; p = 0.03; 95% CI, 1.02-4.2). At 24 hours, TT levels were no longer associated with poor outcome, while estradiol levels were significantly associated with nearly a fourfold higher independent risk of MOF (OR, 3.9; p = 0.04, 95% CI, 1.05-13).

CONCLUSION

Early elevations and increasing testosterone levels over initial 24 hours after injury are associated with an exaggerated inflammatory response and a significantly greater risk of MOF and NI. High estrogen levels at 24 hours are independently associated with an increased risk of MOF. The current analysis suggests that an early evolving testosterone to estrogen hormonal environment is associated with a significantly higher independent risk of poor outcome following traumatic injury.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level II.

Significant sex-based outcome differences in severely injured Chinese trauma patients

A body of experimental evidence suggests that the female sex is associated with a lower risk of mortality after trauma-hemorrhage. However, controversy remains regarding the mechanism responsible for these differences and if basic science findings correspond to clinical differences. Racial disparities in trauma outcomes have also been increasingly described. Until now, research on the association between sex and trauma patient outcomes mainly focused on patients in Europe and the United States. Our research attempted to determine whether the female sex is associated with a survival advantage among severely injured Chinese trauma patients. A retrospective analysis of data derived from the Emergency Intensive Care Unit of the Shanghai Sixth People';s Hospital Acute Trauma Center during 2010 to 2013 was performed to characterize differences in sex-based outcomes after severe blunt trauma. The patient study cohort (858 Asian subjects) was then stratified by age and injury severity (using the Injury Severity Score [ISS]). Crude and adjusted odds ratios (ORs) were calculated to evaluate the association between sex and nosocomial infection rate and hospitalized mortality, both overall and by age and ISS category subgroups. Among all trauma patients, females had a significantly lower risk of in-hospital mortality compared with males (OR, 0.41; 95% confidence interval [95% CI], 0.20 - 0.85). This difference was most apparent for patients younger than 50 years (OR, 0.31; 95% CI, 0.12 - 0.82) and the group with ISS scores of 25 or higher (OR, 0.39; 95% CI, 0.17 - 0.91). No differences in the development of nosocomial infections between sexes were seen among the overall patient group and subgroups. This study revealed a statistically significant association between sex and mortality among severe blunt trauma patients, particularly those patients younger than 50 years and with ISSs of 25 or higher. Women had significantly lower mortality than men after severe blunt trauma. These results highlight the important role of sex hormones and sex-based outcome differences after severe traumatic injury in the Chinese population.

Acute effects of estradiol on lung inflammation due to intestinal ischemic insult in male rats

Intestinal ischemia and reperfusion (intestinal I/R) causes acute lung inflammation that is characterized by leukocyte migration, increased lung microvascular permeability, and, in severe forms, noncardiogenic pulmonary edema and acute respiratory distress syndrome. Female sex hormones interfere with immune response, and experimental and clinical evidence shows that females are more resistant than males to organ injury caused by gut trauma. To reduce the lung inflammation caused by intestinal I/R, we have acutely treated male rats with estradiol. Intestinal I/R was performed by the clamping (45 min) of the superior mesenteric artery (SMA), followed by 2 h of intestinal reperfusion (unclamping SMA). Groups of rats received 17β estradiol (E2, 280 µg/kg, i.v., single dose) 30 min after the SMA occlusion (ischemia period) or 1 h after the unclamping of SMA (reperfusion period). Leukocytes influx into the lung and microvascular leakage were assessed by lung myeloperoxidase activity and Evans blue dye extravasation, respectively. The lung expression of adhesion molecules (intercellular adhesion molecule 1, platelet endothelial cell adhesion molecule 1, and vascular cell adhesion molecule [VCAM]) was evaluated by immunohistochemistry. Interleukin 1β (IL-1β), IL-10, and NOx concentrations were quantified in supernatants of cultured lung tissue. We have found that intestinal I/R increased the lung myeloperoxidase activity and Evans blue dye extravasation, which were reduced by treatment of rats with E2. Intestinal I/R increased ICAM-1 expression only, and it was decreased by E2 treatment. However, E2 treatment reduced the basal expression of platelet endothelial cell adhesion molecule 1. E2 treatment during intestinal ischemia was effective to reduce the levels of IL-10 and IL-1β in explant supernatant, but only IL-10 levels were reduced by E2 at reperfusion phase. The treatment with E2 did not affect NOx concentration. Taken together, our data suggest that estradiol modulates the lung inflammatory response induced by lung injury, likely by acute effects. Thus, acute estradiol treatment could be considered as a potential therapeutic agent in ischemic events.

Women are more than twice as likely to die from burns as men in Australia and New Zealand: an unexpected finding of the Burns Evaluation And Mortality (BEAM) Study

While the risk of death after nonthermal trauma and sepsis may be higher for men, sex differences in outcome after burns are inconsistently reported. The Burns Evaluation And Mortality Study examined the outcomes of all patients admitted after thermal injury to the intensive care unit (ICU) at 8 of 9 burn referral centers in Australia and New Zealand between January 1, 2005, and December 31, 2011. There were 348 women and 1367 men treated for acute burns. Women were older, had more extensive burns, and higher severity of illness scores. Women spent longer in hospital and in ICU than men. Mortality among women was higher than in men (21% vs 8.3%, P<.001). Trends toward a survival disadvantage for women were seen across all ages, at all levels of severity of illness, at every proportion of body surface area burnt, and across all centers. After adjusting for confounding factors, women had more than double the risk of death compared with men (odds ratio, 2.35; 95% confidence interval, 1.38-4.01; P=.002). Our study conclusively shows worse outcomes for women with burns admitted to ICUs in Australia and New Zealand. Further research is required to determine why this is happening.

Effects of 17ß-Estradiol on the Acute Necrotizing Pancreatitis after Onset in Rats

The aim of this study was to investigate the influence of 17ß-estradiol (E2) on acute necrotizing pancreatitis (ANP) induced by glycodeoxycholic acid in rats. Rats were divided into six groups as sham + saline, sham + single dose E2 (SDE2), sham + multiple dose E2 (MDE2), ANP + saline, ANP + SDE2, and ANP + MDE2. ANP in rats was induced by glycodeoxycholic acid. The extent of acinar cell injury, mortality, systemic cardiorespiratory variables, functional capillary density (FCD), renal/hepatic functions, and changes in some enzyme markers for pancreatic and lung tissue were investigated during ANP in rats. The induction of ANP resulted in a significant increase in the mortality rate, pancreatic necrosis, and serum activity of amylase, alanine aminotransferase (ALT), interleukin (IL)-6, lactate dehydrogenase (LDH) in bronchoalveolar lavage (BAL) fluid, serum concentration of urea, and tissue activity of myeloperoxidase (MPO) and malondialdehyde (MDA) in the pancreas and lung, and a significant decrease in concentrations of calcium, blood pressure, urine output, p02, and functional capillary density (FCD). The use of E2 did not alter these changes. E2 demonstrated no effect on the course of ANP in rats. Therefore, it has no value in the treatment during acute pancreatitis.

Characterization of acute coagulopathy and sexual dimorphism after injury: females and coagulopathy just do not mix

BACKGROUND

Acute traumatic coagulopathy (ATC) predicts poor outcome after injury. Females have been demonstrated to be hypercoagulable early in the posttrauma period. It remains unclear whether presence of ATC alters sex-based outcomes after injury. This study's objective was to characterize the sex dimorphism after severe injury in the presence and absence of ATC.

METHODS

Data were obtained from a multicenter prospective cohort study of patients with blunt trauma and hemorrhagic shock. ATC was defined as arrival international normalized ratio (INR) of greater than 1.5. Cox regression was used to determine the independent risks of mortality and multiple-organ failure associated with sex in subjects with ATC and without (non-ATC) while controlling for important confounders. The sex mortality differences were characterized over time to determine at what point after injury any differential risks diverge.

RESULTS

Of 2,007 enrolled subjects, 1,877 had an arrival INR with 439 (23%) having ATC. There was no difference in incidence of ATC across sex (24% vs. 23%; p = 0.95). In the ATC group, no difference in Injury Severity Score, arrival INR, base deficit, temperature, or 24-hour blood requirements were found across sex. Cox hazard regression revealed that sex was not associated with mortality in non-ATC patients (hazard ratio, 0.94; 95% confidence interval, 0.6-1.5). Female sex was independently associated with mortality only in the ATC group (hazard ratio, 2.04; 95% confidence interval, 1.1-3.9; p = 0.03). These mortality risk differences across sex diverged within the first 24 hours after injury.

CONCLUSION

An exaggerated sex dimorphism exists for patients with ATC, with females demonstrating a twofold higher independent risk of mortality. These differential mortality risks across sex diverge early after injury, suggesting that they may be caused by an ongoing hemorrhage. Females who present with ATC at admission have a significantly greater risk of poor outcome. Further studies are warranted to explore the mechanisms responsible for sex dimorphism in the setting of ATC.

LEVEL OF EVIDENCE

Prognostic study, level II.

17β-Estradiol attenuates cytokine-induced nitric oxide production in rat hepatocyte

OBJECTIVE

Nitric oxide (NO) regulation during shock and sepsis is complex. NO production by endothelial NO synthase maintains microvascular perfusion and prevents shock-induced organ injury. However, the overproduction of NO by inducible NO synthase (iNOS) contributes to liver dysfunction after shock and is associated with increased tissue damage and mortality. Estrogen improves organ function and outcome after shock and sepsis, but the mechanism is unknown. We hypothesized that 17β-estradiol would improve organ function by regulating the production of hepatocyte NO.

METHODS

Isolated rat hepatocytes were stimulated in vitro with pro-inflammatory cytokines to induce NO synthesis with or without estrogen. Nitrite was detected after 24 hours. INOS protein was determined using Western blot analysis.

RESULTS

Cytokine stimulation increased nitrite and iNOS protein in a dose-dependent manner. The cytokine-induced nitrite increase was significantly decreased by estrogen. iNOS expression was also diminished in cultures with the higher doses of estrogen.

CONCLUSION

17β-Estradiol decreases cytokine-stimulated iNOS expression and NO production. The down-regulation of iNOS expression may account for the beneficial role of estrogens in models of sepsis and shock.

Testosterone depletion or blockade in male rats protects against trauma hemorrhagic shock-induced distant organ injury by limiting gut injury and subsequent production of biologically active mesenteric lymph

BACKGROUND

We tested the hypothesis that testosterone depletion or blockade in male rats protects against trauma hemorrhagic shock-induced distant organ injury by limiting gut injury and subsequent production of biologically active mesenteric lymph.

METHODS

Male, castrated male, or flutamide-treated rats (25 mg/kg subcutaneously after resuscitation) were subjected to a laparotomy (trauma), mesenteric lymph duct cannulation, and 90 minutes of shock (35 mm Hg) or trauma sham-shock. Mesenteric lymph was collected preshock, during shock, and postshock. Gut injury was determined at 6 hours postshock using ex vivo ileal permeability with fluorescein dextran. Postshock mesenteric lymph was assayed for biological activity in vivo by injection into mice and measuring lung permeability, neutrophil activation, and red blood cell deformability. In vitro neutrophil priming capacity of the lymph was also tested.

RESULTS

Castrated and flutamide-treated male rats were significantly protected against trauma hemorrhagic shock (T/HS)-induced gut injury when compared with hormonally intact males. Postshock mesenteric lymph from male rats had a higher capacity to induce lung injury, Neutrophil (PMN) activation, and loss of red blood cell deformability when injected into naïve mice when compared with castrated and flutamide-treated males. The increase in gut injury after T/HS in males directly correlated with the in vitro biological activity of mesenteric lymph to prime neutrophils for an increased respiratory burst.

CONCLUSIONS

After T/HS, gut protective effects can be observed in males after testosterone blockade or depletion. This reduced gut injury contributes to decreased biological activity of mesenteric lymph leading to attenuated systemic inflammation and distant organ injury.

Life or death? A physiogenomic approach to understand individual variation in responses to hemorrhagic shock

Severe hemorrhage due to trauma is a major cause of death throughout the world. It has often been observed that some victims are able to withstand hemorrhage better than others. For decades investigators have attempted to identify physiological mechanisms that distinguish survivors from nonsurvivors for the purpose of providing more informed therapies. As an alternative approach to address this issue, we have initiated a research program to identify genes and genetic mechanisms that contribute to this phenotype of survival time after controlled hemorrhage. From physiogenomic studies using inbred rat strains, we have demonstrated that this phenotype is a heritable quantitative trait, and is therefore a complex trait regulated by multiple genes. Our work continues to identify quantitative trait loci as well as potential epigenetic mechanisms that might influence survival time after severe hemorrhage. Our ultimate goal is to improve survival to traumatic hemorrhage and attendant shock via regulation of genetic mechanisms and to provide knowledge that will lead to genetically-informed personalized treatments.

Sex-specific social regulation of inflammatory responses and sickness behaviors

In many mammals, the availability of familiar conspecifics in the home environment can affect immune function and morbidity. Numerous sex differences exist in immune responses, but whether the social environment impacts the immune system differently in males and females is not fully understood. This study examined behavioral and physiological responses to simulated bacterial infection in adult male and female Wistar rats housed either with three same-sex non-siblings (Group) or alone (Isolate). Rats were injected with bacterial lipopolysaccharide (Escherichia coli LPS; 150 microg/kg, i.p.), and behavioral (orectic, locomotor, and social) and physiological (thermoregulatory, cytokine, and corticosterone) inflammatory responses were measured. Among males, LPS-induced fever, suppressed locomotor activity, and inhibited feeding behavior and the magnitude of these responses were greater in Isolate relative to Group housed individuals. In contrast, among females group housing exacerbated behavioral and physiological symptoms of simulated infection. LPS treatments elicited IL-1beta production in all groups, but plasma IL-1beta concentrations were higher and peaked earlier in Isolate relative to Group males, and in Group relative to Isolate females. Furthermore, plasma concentrations of TNFalpha and IL-2 were higher in Group relative to Isolate males. Plasma corticosterone concentrations did not vary as a function of social housing conditions. Together, the data indicate that the social environment markedly influences innate immune responses. Group housing exacerbates inflammatory responses and sickness behaviors in females, but attenuates these responses in males. These sex differences are mediated in part by differential effects of the social environment on pro- and anti-inflammatory cytokine production.

Estrogen receptor hormone agonists limit trauma hemorrhage shock-induced gut and lung injury in rats

BACKGROUND

Acute lung injury (ALI) and the development of the multiple organ dysfunction syndrome (MODS) is a major cause of death in trauma patients. Earlier studies in trauma hemorrhagic shock (T/HS) have documented that splanchnic ischemia leading to gut inflammation and loss of barrier function is an initial triggering event that leads to gut-induced ARDS and MODS. Since sex hormones have been shown to modulate the response to T/HS and proestrous (PE) females are more resistant to T/HS-induced gut and distant organ injury, the goal of our study was to determine the contribution of estrogen receptor (ER)alpha and ERbeta in modulating the protective response of female rats to T/HS-induced gut and lung injury.

METHODS/PRINCIPAL FINDINGS

The incidence of gut and lung injury was assessed in PE and ovariectomized (OVX) female rats subjected to T/HS or trauma sham shock (T/SS) as well as OVX rats that were administered estradiol (E2) or agonists for ERalpha or ERbeta immediately prior to resuscitation. Marked gut and lung injury was observed in OVX rats subjected to T/HS as compared to PE rats or E2-treated OVX rats subjected to T/HS. Both ERalpha and ERbeta agonists were equally effective in limiting T/HS-induced morphologic villous injury and bacterial translocation, whereas the ERbeta agonist was more effective than the ERalpha agonist in limiting T/HS-induced lung injury as determined by histology, Evan's blue lung permeability, bronchoalevolar fluid/plasma protein ratio and myeloperoxidase levels. Similarly, treatment with either E2 or the ERbeta agonist attenuated the induction of the intestinal iNOS response in OVX rats subjected to T/HS whereas the ERalpha agonist was only partially protective.

CONCLUSIONS/SIGNIFICANCE

Our study demonstrates that estrogen attenuates T/HS-induced gut and lung injury and that its protective effects are mediated by the activation of ERalpha, ERbeta or both receptors.

Estrogenic hormone modulation abrogates changes in red blood cell deformability and neutrophil activation in trauma hemorrhagic shock

BACKGROUND

Decreased red blood cell (RBC) deformability and activation of neutrophils (polymorphonuclear leukocytes [PMN]) after trauma-hemorrhagic shock (T/HS) have been implicated in the development of multiple organ dysfunction. Experimentally, female animals seemed to be protected from the effects of T/HS, at least in part, because of elevated estrogen levels. Thus, we examined the relative role of estrogen receptor (ER)-alpha and -beta in this protective response.

METHODS

To accomplish this goal, RBC deformability and neutrophil respiratory burst activity were measured in several groups of hormonally intact or ovariectomized (OVX) female rats subjected to T/HS (laparotomy plus hemorrhage to an MAP of 30 mm Hg to 35 mm Hg for 90 minutes) or trauma-sham shock (T/SS) and 3 hours of reperfusion. These groups included rats receiving vehicle, estradiol, or either an ER-alpha agonist or an ER-beta agonist administered at the end of the shock period just before volume resuscitation.

RESULTS

RBC deformability and neutrophil activation were similar among all the T/SS groups and were not different from that observed in the non-OVX female rats subjected to T/HS. In contrast, RBC deformability was reduced and neutrophil activation was increased in the OVX, T/HS female rats as compared with the T/SS groups or the non-OVX, T/HS rats. The administration of estrogen to the T/HS, OVX rats returned RBC and neutrophil function to normal. Both the ER-alpha and -beta agonist partially, but not completely, protected the OVX rats from T/HS-induced loss of RBC deformability, whereas only the ER-beta agonist prevented the increase in neutrophil activation.

CONCLUSIONS

The protective effects of estrogen on T/HS-induced RBC deformability are mediated, at least in part, via activation of both ER-alpha and -beta, whereas ER-beta activation is involved in limiting T/HS-induced neutrophil activation.

[Long-term liver damage due to trauma]

Severe trauma has a major influence on the visceral organs, especially on the liver. Splanchnic hypotension leads to necrosis of the bile duct cells as well as to damage to hepatocytes. Furthermore, the liver is a very immunologically active organ so that damage to the liver can increase the amount of proinflammatory cytokines. The major complication of post-traumatic damage to the liver is secondary sclerosing cholangitis (SCC) a highly progressive disease for which there is no sufficient therapy except liver transplantation. Therefore it is very important to put all efforts into avoiding posttraumatic liver damage from the very beginning. A sophisticated resuscitation therapy is the most important aspect. Direct peritoneal volume resuscitation is a promising possibility to improve perfusion of the visceral organs. Other possibilities are substitution with 17beta-estradiol as a strongly vasoactive hormone with a positive effect on liver perfusion and interleukin-10 as modulator of the immune reaction caused by the liver.

The effect of gender on patients with moderate to severe head injuries

BACKGROUND

Male and female nervous systems respond differently to traumatic brain injury (TBI) and in vivo research relates this difference to neuroprotection from female sex hormones. Attempts to replicate female sex hormone-related neuroprotection in clinical studies have been unsuccessful. The objective of this study was to determine whether gender or menopausal status affects mortality in patients with moderate to severe TBI.

METHODS

A retrospective review of all patients with isolated moderate to severe TBI was undertaken using data from the National Trauma Database version 6.2 (2000-2005). Isolated TBI was defined as head Abbreviated Injury Score >/=3 in patients without significant extracranial injuries (Abbreviated Injury Score <3 for other anatomic regions). Demographics, Injury Severity Score, and outcomes (mortality, intensive care unit and hospital length of stay, and complications) were compared. The population was stratified into age subgroups: 14 to 45 years (premenopausal), 46 to 55 years (perimenopausal), and older than 55 years (postmenopausal). Logistic regression analysis was used to determine the relationship among female gender, mortality, and development of complications after moderate to severe TBI.

RESULTS

A total of 72,294 patients with moderate to severe TBI were evaluated. Females showed a significantly lower risk in both mortality (adjusted odds ratios [AOR], 0.82; 95% confidence intervals [CI], 0.77-0.87; p < 0.0001) and in developing any type of complications (AOR, 0.88; 95% CI, 0.84-0.93; p < 0.0001) than the male population after adjusting for differences in patient characteristics. After age stratification, perimenopausal women (46-55 years) and postmenopausal women (older than 55 years) showed a significantly lower risk in mortality (AOR, 0.76; 95% CI, 0.63-0.92; p < 0.0044 and AOR, 0.79; 95% CI, 0.73-0.86; p < 0.0001, respectively). There was no difference in mortality in premenopausal women compared with their male age-matched counterparts (AOR, 1.09; 95% CI, 0.99-1.21; p = 0.0917).

CONCLUSIONS

Female gender is independently associated with reduced mortality and decreased complications after TBI. As peri- and postmenopausal women demonstrated improved survival, and premenopausal women did not, estrogen unlikely confers neuroprotection in women after TBI. Future TBI treatment may benefit with further research focused on why peri- and postmenopausal women show decreased mortality after TBI.

Systematic analysis of the salutary effect of estrogen on cardiac performance after trauma-hemorrhage

Although 17beta-estradiol (estrogen) and estrogen receptor (ER) agonist administration after trauma-hemorrhage improves cardiac function, it remains unknown what the optimal estrogen or ER agonist dosage is to elicit this beneficial effect. To study this, the dose-dependent effects of estrogen, propylpyrazole triol (ER-alpha agonist), and diarylpropionitrile (DPN; ER-beta agonist) on heart performance (+dP/dt) were determined in sham rats and in experimental animals at the time of maximal bleedout (MBO) or at 2 h after trauma-hemorrhage. The results showed that estrogen and DPN induced dose-dependent increases in the maximal rate of left ventricular pressure increase (+dP/dt) in all groups, whereas propylpyrazole triol was ineffective at all doses. The maximal dose and the 50% effective dose of DPN were approximately 100-fold lower than those of estrogen. The half-life of estrogen in plasma was approximately 25 min in sham and MBO groups. A positive correlation between the estrogen-induced increase in +dP/dt and survival in MBO rats were observed. These results collectively suggest that the salutary effects of estrogen on cardiac performance are dose-dependent and mediated via ER-beta.

The role of estrogen and receptor agonists in maintaining organ function after trauma-hemorrhage

Sex is increasingly recognized as a major factor in the outcome of patients who have trauma and sepsis. Moreover, sex steroids influence chemokine/adhesion molecule expression and neutrophil accumulation. Heat shock proteins, heat shock factor 1, and peroxisome proliferator-activated receptor [gamma] coactivator 1 are regulated by the estrogen receptors and consequently contribute to organ protection after trauma-hemorrhage. Additionally, sex steroids regulate inflammatory cytokines, leading to increased morbidity and mortality. This article deals with trauma-hemorrhage and examines the following: 1) the evidence for sex differences; 2) the mechanisms by which sex hormones affect organ protection; 3) the tissue-specific effect of sex hormone receptors; and 4) the effect of genomic and nongenomic (i.e. membrane-initiated steroid signaling) pathways of sex hormones after trauma. The available information indicates that sex steroids modulate cardiovascular responses after trauma. Thus, alteration or modulation of the prevailing hormone milieu at the time of injury seems to be a novel therapeutic option for improving outcome after injury

Activation of endoplasmic reticulum stress response following trauma-hemorrhage

Hemorrhagic trauma leads to organ dysfunction, sepsis and death. There is abnormal production of proinflammatory cytokines by Kupffer cells, tissue hypoxia and liver injury following trauma-hemorrhage. The physiological conditions consequent to trauma-hemorrhage are consistent with factors necessary to initiate endoplasmic reticulum (ER) stress and unfolded protein response. However, the contribution of ER stress to apoptosis and liver injury after trauma-hemorrhage is not known. In the present study ER stress was investigated in mice that underwent trauma-hemorrhage or sham operation. Expressions of endoplasmic reticulum stress proteins Bip, ATF6, PERK, IRE1alpha, and PDI were significantly elevated in the liver after trauma-hemorrhage compared to the controls. The ER stress associated proapoptotic transcription factor CHOP protein expression was also significantly elevated in trauma-hemorrhage group. Consistent with this, enhanced DNA fragmentation was observed, confirming apoptosis, in the liver following trauma-hemorrhage. These results demonstrate the initiation of ER stress and its role in apoptosis and liver injury, subsequent to hemorrhagic trauma.

Sex steroids/receptor antagonist: their use as adjuncts after trauma-hemorrhage for improving immune/cardiovascular responses and for decreasing mortality from subsequent sepsis

Studies in human as well as animal models demonstrate that females in the proestrus cycle (i.e., with high estrogen) tolerate trauma-hemorrhage and sepsis far better than males. The female sex steroid, estrogen, is the significant factor contributing to this observed gender difference in outcome. One reason for the lack of significant gender association in some clinical studies is the possibility of heterogeneity of the population in terms of their hormonal status at the time of injury. Several experimental investigations have revealed that androgens produce immune and cardiovascular depression after trauma-hemorrhage. However, the use of an androgen receptor antagonist after trauma-hemorrhage has salutary effects of immune and cardiovascular function. Likewise, estrogen produces beneficial effects on immune and cardiovascular function after trauma-hemorrhage and significantly decreases mortality rates from subsequent sepsis. The salutary effects of estrogen after trauma-hemorrhage have been shown to be due to both genomic and nongenomic effects. Thus, the use of an estrogen or androgen receptor antagonist as an adjunct after trauma-hemorrhage is a safe and novel approach for restoring immune and cardiovascular function after trauma-hemorrhage and for decreasing the mortality from subsequent sepsis.

Characterization of the gender dimorphism after injury and hemorrhagic shock: are hormonal differences responsible?

OBJECTIVE

To characterize the gender dimorphism after injury with specific reference to the reproductive age of the women (young, <48 yrs of age, vs. old, >52 yrs of age) in a cohort of severely injured trauma patients for which significant variation in postinjury care is minimized.

DESIGN

Secondary data analysis of an ongoing prospective multicenter cohort study.

SETTING

Academic, level I trauma and intensive care unit centers.

PATIENTS

Blunt-injured adults with hemorrhagic shock.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Separate Cox proportional hazard regression models were formulated based on all patients to evaluate the effects of gender on mortality, multiple organ failure, and nosocomial infection, after controlling for all important confounders. These models were then used to characterize the effect of gender in young and old age groups. Overall mortality, multiple organ failure, and nosocomial infection rates for the entire cohort (n = 1,036) were 20%, 40%, and 45%, respectively. Mean Injury Severity Score was 32 +/- 14 (mean +/- SD). Men (n = 680) and women (n = 356) were clinically similar except that men required higher crystalloid volumes, more often had a history of alcoholism and liver disease, and had greater ventilatory and intensive care unit requirements. Female gender was independently associated with a 43% and 23% lower risk of multiple organ failure and nosocomial infection, respectively. Gender remained an independent risk factor in young and old subgroup analysis, with the protection afforded by female gender remaining unchanged.

CONCLUSIONS

The independent protective effect of female gender on multiple organ failure and nosocomial infection rates remains significant in both premenopausal and postmenopausal women when compared with similarly aged men. This is contrary to previous experimental studies and the known physiologic sex hormone changes that occur after menopause in women. These results suggest that factors other than sex hormones may be responsible for gender-based differences after injury.

Male gender is associated with excessive IL-6 expression following severe injury

OBJECTIVE

An important and persistent laboratory finding has been that males and females respond differently after traumatic injury and hemorrhagic shock. We have previously presented clinical data showing that male gender is independently associated with a 40% higher rate of multiple organ failure (MOF) and a 25% higher rate of nosocomial infection (NI) after injury; however, the mechanism responsible for this dimorphic response after injury has not been adequately characterized clinically.

METHODS

Data were obtained from a multicenter prospective cohort study evaluating clinical outcomes in severely injured adults with blunt hemorrhagic shock. Proteomic analysis of serum inflammatory cytokines, on days 0, 1, and 4 postinjury, was performed on 46 males and 34 females. Repeated measures ANOVA were used to compare serial IL-1beta, TNF-alpha, IL-6, IL-8, and IL-10 serum levels across gender, while controlling for important confounders. Logistic regression modeling was then used to analyze the independent risk of MOF and NI associated with gender.

RESULTS

IL-6 serum levels were statistically higher in males relative to females (p = 0.008). This higher level of IL-6 expression in males remained statistically significant over time even after controlling for differences in age, initial base deficit, ISS, and 12-hour blood transfusion requirements (p = 0.025). No differences in IL-1beta serum levels (p = 0.543), TNF-alpha, (p = 0.200) IL-8 (p = 0.107), and IL-10 (p = 0.157) were found. Males had a higher crude incidence of MOF and an 11-fold higher independent risk of MOF.

CONCLUSIONS

Persistently elevated IL-6 levels in males are associated with a higher rate of MOF. It is not known if this excessive IL-6 expression in males is causal or only a marker for poor outcome. Further studies are required to elucidate if this early, persistent IL-6 expression is responsible for the gender-based differential outcomes after injury.

The effect of estrogen on hepatic microcirculation after ischemia/reperfusion

BACKGROUND AND AIMS

Gender dimorphism in clinical manifestation of sepsis, hemorrhage, and trauma is still under investigation. Several experimental studies have indicated a protective effect of estrogen. Nonetheless, the effect of gender on hepatic ischemia/reperfusion remains controversially discussed, and the influence of estrogen is still unclear. In the present study, we investigated whether hepatic ischemia/reperfusion (I/R) injury is gender-dependent and if hepatic microvascular reperfusion injury can be prevented by estrogen.

MATERIALS AND METHODS

Eight female and eight male Sprague-Dawley rats were subjected to 90 min left lobar ischemia followed by 60 min reperfusion. Additional six males were pretreated with 17beta-estradiol 24 h before I/R. Six female and six male rats served as nonischemic sham animals. By means of intravital microscopy, sinusoidal perfusion, leukocyte-endothelial cell interaction, and Kupffer cell activity were analyzed. Finally, arterial blood and liver tissue samples were taken for histomorphological analysis and liver enzyme determination.

RESULTS

After hepatic ischemia/reperfusion, animals revealed a significant gender-specific impairment of hepatic microcirculation, whereas Kupffer cell depression, sinusoidal perfusion failure, leukocyte-endothelial cell interaction within post sinusoidal venules, and parenchymal liver cell damage were more pronounced in male animals. Pretreatment with estrogen caused a normalization of Kupffer cell dysfunction and an amelioration of sinusoidal perfusion failure and venular leukocyte-endothelial cell interaction. However, estrogen did not protect from manifestation of post ischemic parenchymal cell damage.

CONCLUSION

Hepatic ischemia and reperfusion generate a gender-specific occurrence of microvascular injury, which seems to be partially mediated by estrogen. However, additional factors may contribute to the initial post ischemic parenchymal cell damage.

Glucosamine administration improves survival rate after severe hemorrhagic shock combined with trauma in rats

We have previously shown that glucosamine administration resulted in higher cardiac output and improved tissue perfusion after trauma-hemorrhage with resuscitation in rats, which was associated with the increased levels of protein O-linked-N-acetylglucosamine (O-GlcNAc). The purpose of the study was to evaluate the effect of glucosamine on the survival, without resuscitation, in rats. Adult male rats underwent midline laparotomy and 55% of total blood volume was withdrawn for 25 min under isoflurane anesthesia. At the end of the hemorrhage period, 2.5 mL of 150 mM glucosamine or equivalent osmolarity of mannitol solution was injected intravenously for 10 min. The survival time, mean blood pressure, heart rate, and central body temperature were monitored continuously; then, the O-GlcNAc levels in heart, brain, liver, and muscle were measured by means of Western blot analysis. Glucosamine administration significantly increased the survival rate in comparison with mannitol administration (percentage of survival after 2 h, 47% vs. 20%; P < 0.05). The mean arterial pressure was significantly higher in the glucosamine group for 18 min after treatment. The protein O-GlcNAc levels, assessed 30 min after glucosamine treatment, were significantly increased in the heart, brain, and liver. These data demonstrate that i.v. glucosamine administration improves the survival rate after trauma-hemorrhage without resuscitation; this effect may be related to the glucosamine-induced increase in protein O-glycosylation. Furthermore, the increase in mean arterial pressure may suggest a vasoactive and/or positive inotropic effect of glucosamine in hypovolemic shock.

Gender dimorphism following injury: making the connection from bench to bedside

Despite ongoing prevention efforts, injury remains the leading cause of mortality over the first three decades of life in the United States. Those who survive their initial injury continue to be plagued with the development of sepsis and multiple organ failure and their attributable morbidity and mortality. An important and persistent finding has been that males and females respond differently following traumatic injury and hemorrhagic shock. A significant advancement in the experimental understanding of the gender dimorphism in response to trauma-hemorrhage and sepsis has occurred. Experimental evidence for the differential effects of sex hormones on cell-mediated immunity and organ system tolerance of shock continues to expand. Clinical studies, however, have been unable to reproduce these laboratory bench findings consistently. There continues to be a divide between the "bench and bedside" in regard to our understanding of gender-based differences following injury. Relative to controlled animal experiments, predisposing comorbidities, injury characteristics, and a lack of information about the hormone milieu of the trauma patient disallow reproducible results from clinical analyses. Continued clinical research into potential sex hormone-based differences, genetic differences, and the cellular and molecular mechanisms responsible for these gender-based differential responses is required to close this gap. This may ultimately promote therapeutic interventions, which will allow for improved outcomes for males and females in the near future.

Metabolic modulators following trauma sepsis: Sex hormones

BACKGROUND

The development of metabolic perturbations following severe trauma/sepsis leading to decreased energy production, hyperglycemia, and lipolysis is often rapid. Gender is increasingly recognized as a major factor in the outcome of patients suffering from trauma/sepsis. Moreover, sex hormones influence energy, glucose, and lipid metabolism. Metabolic modulators, such as peroxisome proliferator-activated receptor-gamma coactivator-1 and peroxisome proliferator-activated receptor-alpha, which are required for mitochondrial energy production and fatty acid oxidation, are regulated by the estrogen receptor-beta and consequently contribute to cardioprotection following trauma hemorrhage. Additionally, sex steroids regulate inflammatory cytokines that cause hypermetabolism/catabolism via acute phase response, leading to increased morbidity and mortality.

MEASUREMENTS

This article examines the following: (1) the evidence for gender differences; (2) energy, glucose, and lipid metabolism and the acute phase protein response; (3) the mechanisms by which gender/sex hormones affect the metabolic modulators; and (4) the tissue-specific effect of sex hormone receptors and the effect of genomic and nongenomic pathways of sex hormones following trauma.

RESULTS AND CONCLUSIONS

The available information indicates that sex steroids not only modulate the immune/cardiovascular responses but also influence various metabolic processes following trauma. Thus, alteration or modulation of the prevailing hormone milieu at the time of injury appears to be a novel therapeutic adjunct for improving outcome after injury.

The protective effects of PUGNAc on cardiac function after trauma-hemorrhage are mediated via increased protein O-GlcNAc levels

We have previously shown that administration of glucosamine after trauma-hemorrhage (TH) improved cardiac output and organ perfusion, and this was associated with increased levels of O-linked N-acetylglucosamine (O-GlcNAc) on proteins in the heart and brain. An alternative means of increasing O-GlcNAc levels is by inhibition of O-linked N-acetylglucosaminidase, which catalyzes the removal of N-acetylglucosamine from proteins, with O-(2-acetamido-2-deoxy-d-glucopyranosylidene) amino-N-phenylcarbamate (PUGNAc). The goal of this study, therefore, was to determine whether PUGNAc administration after TH also improves recovery of organ perfusion and function. Fasted male rats were bled to and maintained at a mean arterial blood pressure of 40 mmHg for 90 min, followed by fluid resuscitation. Intravenous administration of PUGNAc (200 micromol/kg body weight) 30 min after the onset of resuscitation significantly improved cardiac output compared with the vehicle controls (12.3 +/- 1.3 mL/min per 100 g body weight vs. 25.5 +/- 2.0 mL/min per 100 g body weight; P < 0.05), decreased total peripheral resistance (6.6 +/- 0.8 mmHg/mL per minute per 100 g body weight vs. 3.7 +/- 0.3 mmHg/mL per minute per 100 g body weight; P < 0.05), and increased perfusion of critical organ systems, including the kidney and liver, determined at 2 h after the end of resuscitation. Treatment with PUGNAc also attenuated the TH-induced increase in plasma IL-6 levels (864 +/- 112 pg/mL vs. 392 +/- 188 pg/mL; P < 0.05) and TNF-alpha levels (216 +/- 21 pg/mL vs. 94 +/- 11 pg/mL; P < 0.05) and significantly increased O-GlcNAc levels in the heart, liver, and kidney. Thus, PUGNAc, like glucosamine, improves cardiac function and organ perfusion and reduced the level of circulating IL-6 and TNF-alpha after TH. The similar effects of glucosamine and PUGNAc support the notion that the protection associated with both interventions is mediated via increased protein O-GlcNAc levels.

G protein-coupled receptor 30-dependent protein kinase A pathway is critical in nongenomic effects of estrogen in attenuating liver injury after trauma-hemorrhage

Although nongenomic effects of 17beta-estradiol (E2) are mediated via the estrogen receptor alpha (ER-alpha), the existence of another novel ER, G protein-coupled receptor 30 (GPR30), has been suggested as a candidate for triggering a broad range of E2-mediated signaling. GPR30 also acts independently of the ER to promote activation of the protein kinase A (PKA) pathway, which protects cells from apoptosis through Bcl-2. In this study, we examined whether the salutary effects of E2 in attenuating hepatic injury after trauma-hemorrhage are mediated via GPR30- or ER-alpha-regulated activation of PKA-dependent signaling. At 2 hours after trauma-hemorrhage, administration of E2-conjugated to bovine serum albumin (E2-BSA, membrane impermeable) or E2 induced the up-regulation of ER-alpha and GPR30 and attenuated hepatic injury. This was accompanied by increases in PKA activity and Bcl-2 expression. Inhibition of PKA in E2-BSA-treated trauma-hemorrhage rats by PKA inhibitor H89 prevented the E2-BSA attenuation of hepatic injury. Isolated hepatocytes were transfected with small interfering RNA to suppress GPR30 or ER. We found that suppression of GPR30 but not ER-alpha prevented E2-BSA- or E2-induced PKA activation and Bcl-2 expression. These results suggest that the nongenomic salutary effect of E2 in reducing hepatic injury after trauma-hemorrhage is mediated through the PKA-dependent pathway via GPR30 but not ER-alpha.

Sex hormones affect bone marrow dysfunction after trauma and hemorrhagic shock

OBJECTIVE

Bone marrow (BM) dysfunction after trauma and hemorrhagic shock (T/HS) results in a decrease in clonogenic growth of BM progenitors through a plasma-mediated process. Although sex hormones have been shown to modulate some end-organ injury after shock, post-T/HS BM dysfunction has only been studied in male animals. Therefore, the present study examines the effects of sex hormones on post-T/HS BM dysfunction by measuring clonogenic growth of BM progenitors in castrated male rats and in ovariectomized and proestrus female rats.

DESIGN

Laboratory experiment.

SETTING

University surgical research laboratory.

SUBJECT

Castrated and noncastrated male and ovariectomized and proestrus female Sprague-Dawley rats.

INTERVENTION

All rats were subjected to either T/HS or sham shock with laparotomy (n = 3-5 per group). At 3 hrs after resuscitation, the rats were killed and plasma and BM mononuclear cells from bilateral femurs were harvested.

MEASUREMENTS AND MAIN RESULTS

BM mononuclear cells were cultured for erythroid burst-forming unit and granulocyte-macrophage colony-forming unit colonies to assess the extent of progenitor BM dysfunction. BM from noncastrated male rats subjected to T/HS demonstrated a significant decrease in granulocyte-macrophage colony-forming unit and erythroid burst-forming unit colony formation compared with BM of all the sham shock groups and with the castrated male and both female rat groups subjected to T/HS. In addition, plasma from noncastrated shocked male rats incubated in vitro with BM cells from unmanipulated male rats caused a significant suppression of BM granulocyte-macrophage colony-forming unit and erythroid burst-forming unit colonies compared with plasma from castrated rats subjected to either sham shock with laparotomy or T/HS.

CONCLUSION

The profound BM dysfunction observed in noncastrated male rats after T/HS is not observed in proestrus female rats and castrated male rats. In addition, the in vitro plasma-mediated BM suppression present in male rats after T/HS is also lost in castrated male rats. Sex hormones seem to play a significant role in BM dysfunction after T/HS.

Activation of c-Jun NH2-terminal kinase during islet isolation

Pancreatic islet transplantation has been remarkably improved by the Edmonton protocol; however, it is not easy to achieve insulin independence after islet transplantation from one donor pancreas. The islet isolation procedure itself destroys cellular and noncellular components of the pancreas that probably play a role in supporting islet survival. Further islet transplantation exposes cells to a variety of stressful stimuli such as proinflammatory cytokines. The reduction in islet mass immediately after isolation and transplantation implicates beta cell death by apoptosis and the prerecruitment of intracellular death signalling pathways. The c-Jun NH2-terminal kinases (JNKs) are classic stress-activated protein kinases and many cellular stresses have been shown to stimulate JNK activation. JNK in the pancreas is activated during brain death, pancreas procurement, and organ preservation, and its activity is progressively increased during the isolation procedure. Moreover, JNK activity in the transplanted liver after islet transplantation increases markedly within 24 hrs. Use of the JNK inhibitor in pancreas preservation, islet culture, and/or islet transplantation prevents islet apoptosis and improves islet graft function. These findings suggest that the control of JNK activation is important for pancreatic islet transplantation.

17β-Estradiol modulates vasoconstriction induced by endothelin-1 following trauma-hemorrhage

Although endothelin-1 (ET-1) induces vasoconstriction, it remains unknown whether 17β-estradiol (E2) treatment following trauma-hemorrhage alters these ET-1-induced vasoconstrictive effects. In addition, the role of the specific estrogen receptor (ER) subtypes (ER-α and ER-β) and the endothelium-localized downstream mechanisms of actions of E2 remain unclear. We hypothesized that E2 attenuates increased ET-1-induced vasoconstriction following trauma-hemorrhage via an ER-β-mediated pathway. To study this, aortic rings were isolated from male Sprague-Dawley rats following trauma-hemorrhage with or without E2 treatment, and alterations in tension were determined in vitro. Dose-response curves to ET-1 were determined, and the vasoactive properties of E2, propylpyrazole triol (PPT, ER-α agonist), and diarylpropionitrile (DPN, ER-β agonist) were determined. The results showed that trauma-hemorrhage significantly increased ET-1-induced vasoconstriction; however, administration of E2 normalized ET-1-induced vasoconstriction in trauma-hemorrhage vessels to the sham-operated control level. The ER-β agonist DPN counteracted ET-1-induced vasoconstriction, whereas the ER-α agonist PPT was ineffective. Moreover, the vasorelaxing effects of E2 were not observed in endothelium-denuded aortic rings or by pretreatment of the rings with a nitric oxide (NO) synthase inhibitor. Cyclooxygenase inhibition with indomethacin had no effect on the action of E2. Thus, E2 administration attenuates ET-1-induced vasoconstriction following trauma-hemorrhage via an ER-β-mediated pathway that is dependent on endothelium-derived NO synthesis.

Inhibition of cardiac PGC-1alpha expression abolishes ERbeta agonist-mediated cardioprotection following trauma-hemorrhage

PGC-1alpha (peroxisome proliferator-activated receptor [PPARgamma] coactivator-1alpha) activates PPARalpha and mitochondrial transcription factor A (Tfam), which regulate proteins, fatty acid and ATP metabolism (i.e., FAT/CD36, MCAD, and COX I). Recently we found that the salutary effects of estradiol (E2) on cardiac function following trauma-hemorrhage (T-H) are mediated via estrogen receptor (ER)beta. In this study we tested the hypothesis that ERbeta-mediated cardioprotection is induced via up-regulation of PGC-1alpha through PPARalpha or Tfam-dependent pathway. Male rats underwent T-H and received ERalpha agonist propylpyrazole-triol (PPT), ERbeta agonist diarylpropionitrile (DPN), E2, or vehicle. Another group was treated with antisense PGC-1alpha oligonucleotides prior to administration of DPN. E2 and DPN treatments attenuated the decrease in cardiac mitochondrial ATP, abrogated the T-H-induced lipid accumulation, and normalized PGC-1alpha, PPARalpha, FAT/CD36, MCAD, Tfam, and COX I after T-H. In contrast, PPT administration did not abrogate lipid accumulation. Moreover, in PPT-treated animals mitochondrial ATP remained significantly lower than those observed in DPN- or E2-treated animals. Prior administration of antisense PGC-1alpha prevented DPN-mediated cardioprotection and increase in ATP levels and Tfam but not in PPARalpha following T-H. These findings suggest that the salutary effects of E2 on cardiac function following T-H are mediated via ERbeta up-regulation of PGC-1alpha through Tfam-dependent pathway.

Neutrophil activation is modulated by sex hormones after trauma-hemorrhagic shock and burn injuries

Recent literature indicates that females are more resistant to shock-, trauma-, and sepsis-induced immune dysfunction and organ injury than are males. Consequently, using trauma-hemorrhagic shock (T/HS) and burn models, we tested whether the neutrophil response to trauma occurred in a sexually dimorphic fashion and, if so, the role of sex hormones. Neutrophil activation, as reflected by CD11b expression and respiratory burst activity, was increased to a greater extent in male rats than in female rats after T/HS or burn injury. Testosterone appeared to potentiate neutrophil activation, because castration reduced neutrophil activation, whereas ovariectomy had little effect. Mechanistically, this sexually dimorphic neutrophil response appeared to be due to both cellular and humoral factors. Evidence for a cellular difference between male and female neutrophils is based on the observation that naive female neutrophils were more resistant to activation by burn or T/HS plasma and lymph than naive male neutrophils and that this resistance varied over the estrus cycle. Additionally, the humoral environment was more neutrophil activating in male rats, because burn and T/HS plasma and lymph from male rats activated naive male neutrophils to a greater extent than comparable samples from females. Last, on the basis of in vitro experiments examining the effects of estrogen on calcium signaling, it appears that estrogen limits trauma-induced neutrophil activation, at least in part, by limiting the entry of calcium into the cell via store-operated calcium entry mechanisms. In conclusion, there is a striking sexual dimorphism in neutrophil responses after trauma, and these changes reflect both cellular resistance to activation as well as a less activating humoral environment.

Gonadal steroids in critical illness

Gonadal steroids are metabolized in target cells and then interact with specific receptors to exert genomic and nongenomic effects. Complex feedback loops that involve the immune-neuroendocrine axis, limbic system, and gonadal steroids play a vital role in the adaptation to critical illness. Preclinical studies demonstrate adverse physiological effects of androgens on the cardiovascular and immune systems despite its purported anabolic effects. Similar models also demonstrate salutary effects of estrogens on these systems. Thus, during the catabolic phases of acute and chronic critical illness, estrogen, and not androgen, therapy may prove to be a valuable intervention. However, during the post-critical illness recovery phase, when anabolism is critical, androgen therapy may still be useful and safe.

Estradiol improves cardiac and hepatic function after trauma-hemorrhage: role of enhanced heat shock protein expression

Although studies indicate that 17β-estradiol administration after trauma-hemorrhage (T-H) improves cardiac and hepatic functions, the underlying mechanisms remain unclear. Because the induction of heat shock proteins (HSPs) can protect cardiac and hepatic functions, we hypothesized that these proteins contribute to the salutary effects of estradiol after T-H. To test this hypothesis, male Sprague-Dawley rats (∼300 g) underwent laparotomy and hemorrhagic shock (35–40 mmHg for ∼90 min) followed by resuscitation with four times the shed blood volume in the form of Ringer lactate. 17β-estradiol (1 mg/kg body wt) was administered at the end of the resuscitation. Five hours after T-H and resuscitation there was a significant decrease in cardiac output, positive and negative maximal rate of left ventricular pressure. Liver function as determined by bile production and indocyanine green clearance was also compromised after T-H and resuscitation. This was accompanied by an increase in plasma alanine aminotransferase (ALT) levels and liver perfusate lactic dehydrogenase levels. Furthermore, circulating levels of TNF-α, IL-6, and IL-10 were also increased. In addition to decreased cardiac and hepatic function, there was an increase in cardiac HSP32 expression and a reduction in HSP60 expression after T-H. In the liver, HSP32 and HSP70 were increased after T-H. There was no change in heart HSP70 and liver HSP60 after T-H and resuscitation. Estradiol administration at the end of T-H and resuscitation increased heart/liver HSPs expression, ameliorated the impairment of heart/liver functions, and significantly prevented the increase in plasma levels of ALT, TNF-α, and IL-6. The ability of estradiol to induce HSPs expression in the heart and the liver suggests that HSPs, in part, mediate the salutary effects of 17β-estradiol on organ functions after T-H.

Flutamide restores cardiac function after trauma-hemorrhage via an estrogen-dependent pathway through upregulation of PGC-1

Although previous studies have shown that flutamide improves cardiovascular function after trauma-hemorrhage, the mechanisms responsible for the salutary effect remain unknown. We hypothesized that flutamide mediates its beneficial effects via an estrogen-dependent pathway through upregulation of peroxisome proliferator-activated receptor-γ coactivator 1 (PGC-1). PGC-1, a key regulator of cardiac mitochondrial ATP production, induces mitochondrial DNA (mtDNA)-encoded genes such as cytochrome- c oxidase (COX) subunit I, II, and III (COX I, COX II, and COX III), which regulates mitochondrial oxidative phosphorylation. To test this hypothesis, male rats underwent trauma-hemorrhage (mean arterial pressure of 35–40 mmHg for ∼90 min) followed by resuscitation. At the onset of resuscitation, rats received vehicle, flutamide (25 mg/kg body wt), flutamide in combination with estrogen receptor (ER) antagonist ICI-182,780 (3 mg/kg body wt), or ICI-182,780 alone. Flutamide administration after trauma-hemorrhage restored the depressed cardiac function and increased cardiac testosterone, estrogen levels, and aromatase activity. These increases were accompanied by normalized cardiac ER-α and ER-β protein levels, PGC-1, and COX I mRNA expression, mitochondrial COX activity, and ATP contents. However, cardiac dihydrotestosterone, 5α-reductase II, androgen receptor protein levels, and mtDNA-encoded genes COX II and COX III were unaffected by flutamide treatment. The flutamide-mediated restoration of cardiac function, the increases in aromatase activity and estrogen levels, ER-α, ER-β, PGC-1, COX I, COX activity, and ATP contents were, however, abolished when ER antagonist ICI-182,780 was administrated along with flutamide. These findings suggest that the salutary effect of flutamide on cardiac function after trauma-hemorrhage is mediated via an estrogen-dependent pathway through upregulation of PGC-1.

PGC-1 upregulation via estrogen receptors: a common mechanism of salutary effects of estrogen and flutamide on heart function after trauma-hemorrhage

Flutamide, an androgen receptor antagonist, is thought to improve cardiovascular function by blocking the androgen receptor after trauma-hemorrhage (T-H). Although 17β-estradiol (E2) and flutamide improve cardiac function after T-H, whether E2 and flutamide produce their salutary effect via the same or a different mechanism is unknown. We hypothesized that E2 and flutamide mediate their effects via estrogen receptor (ER)-mediated upregulation of peroxisome proliferator-activated receptor coactivator 1 (PGC-1). PGC-1, a key regulator of cardiac mitochondrial function, induces mitochondrial genes by activating transcription factors such as nuclear respiratory factor 2 (NRF-2), which regulates mitochondrial proteins [i.e., mitochondrial transcription factor A (Tfam), cytochrome- c oxidase subunit IV, and β-ATP synthase]. Adult male rats underwent T-H [5-cm midline incision and hemorrhage (blood pressure = 40 mmHg for ∼90 min)] and resuscitation. At the onset of resuscitation, rats received vehicle, flutamide (25 mg/kg), or E2 (50 μg/kg). Another group received the ER antagonist ICI-182780 (3 mg/kg) with or without flutamide. Flutamide or E2 administration after T-H restored depressed cardiac function. Moreover, E2 and flutamide normalized expression of cardiac PGC-1, NRF-2, Tfam, cytochrome- c oxidase subunit IV, and the mitochondrial DNA-encoded gene cytochrome- c oxidase subunit I and β-ATP synthase, mitochondrial ATP, and cytochrome- c oxidase activity. However, if the ER antagonist ICI-182780 was administered with flutamide, flutamide-mediated PGC-1 upregulation was totally abolished. These results indicate that E2 and flutamide upregulate PGC-1 via the ER. Thus PGC-1 upregulation appears to be the common mechanism by which E2 and flutamide mediate their salutary effects on cardiac function after T-H.

Salutary effects of androstenediol on hepatic function after trauma-hemorrhage are mediated via peroxisome proliferators-activated receptor gamma

BACKGROUND

A recent study suggested that administration of androstenediol (Adiol) after trauma-hemorrhage (T-H) improves hepatic functions; however, the mechanism responsible for the salutary effect of Adiol remains unknown. Although studies indicate similarities and association between the anti-inflammatory properties of Adiol and peroxisome proliferator-activated receptor gamma (PPARgamma), whether the salutary effects of Adiol are mediated via upregulation of PPARgamma remains unclear.

METHODS

Male Sprague-Dawley rats underwent laparotomy and approximately 90 minutes of hemorrhagic shock (40 mm Hg), followed by resuscitation with 4 times the shed blood volume in the form of Ringer's lactate. Adiol (1 mg per kilogram of body weight, iv) was administered at the end of resuscitation. An additional group of rats were treated with PPARgamma antagonist (GW9662, 1 mg/kg ip) along with Adiol and the rats were sacrificed 5 hours thereafter.

RESULTS

Hepatic functions were markedly depressed and plasma tumor necrosis factor-alpha, C-reactive protein and endothelin-1 were markedly increased after T-H. DNA-binding activity of nuclear factor kappa B and AP-1, and gene expressions of inducible nitric oxide synthase and endothelin-1 in the liver also increased significantly. These parameters were attenuated by Adiol treatment. These effects were accompanied an increased DNA-binding activity of PPARgamma in T-H-Adiol-treated rats. Treatment of rats with GW9662 prevented the salutary effects of Adiol after T-H.

CONCLUSIONS

Since blockade of PPARgamma prevented the salutary effects of Adiol on hepatic functions and proinflammatory factors, this finding suggests that Adiol mediated its salutary effects after T-H via the PPARgamma-related pathways.

Influence of physiological androgen levels on wound healing and immune status in men

Aging in men is associated with a progressive decline in the production of several hormones, including androgens. The extent to which an age-dependent decline in androgen levels lead to health problems or can affect quality of life remains under debate. Clinical results on replacement therapy do not yet provide a definitive clue on the benefit/risk balance. A sexual dimorphism of the immune system is well established, and the differences between female and male immune responses under normal, as well as pathological, conditions are generally attributed to the influence of estrogens, progestins, and androgens. The suppressive effects of male sex hormones on immune functions have been observed in a wide variety of disease processes and appear to be testosterone-mediated. Endogenous testosterone inhibits skin wound healing response in males and is associated with an enhanced inflammatory response. Although there are no known gender-related differences in permeability barrier function in adults, estrogens accelerates--whereas testosterone retards--barrier development in fetal skin, and male fetuses demonstrate slower barrier development than female littermates.

Mechanism responsible for the salutary effects of flutamide on cardiac performance after trauma-hemorrhagic shock: Upregulation of cardiomyocyte estrogen receptors

BACKGROUND

Although flutamide (FTM), an androgen-receptor antagonist, normalizes the depressed immune and cardiac function in males after trauma hemorrhage (T-H), the mechanism responsible for its salutary effects remains unknown. We hypothesized that the salutary effects of FTM are mediated via upregulation of estrogen receptors (ERs).

METHODS

Male Sprague-Dawley rats underwent T-H (laparotomy and 90 minutes of hemorrhage (35-40 mm Hg) and then resuscitated with 4x the volume of shed blood in the form of Ringer's lactate). FTM (25 mg/kg) or vehicle (propanediol) was injected subcutaneously 30 minutes before the end of resuscitation. At 2 hours after T-H or sham operation, cardiac output, stroke volume, heart rate, mean arterial pressure, +/- dp/dt, and total peripheral resistance were measured (n = 6 rats per group). Immediately after the measurement of cardiac function, cardiomyocytes were isolated, RNA was extracted, and expression of ER-alpha, ER-beta, and androgen-receptor (AR) mRNA in cardiomyocytes was determined by quantitative real-time polymerase chain reaction. ER-alpha, ER-beta, and AR protein levels in cardiomyocytes were also measured by Western blot analysis.

RESULTS

The depressed cardiac output, stroke volume, and +/- dp/dt after T-H were significantly improved in the FTM-treated T-H group. Moreover, the decrease in expression of ER-alpha and ER-beta mRNA and protein in cardiomyocytes in the T-H group was prevented with FTM treatment after T-H. However, expression of cardiomyocytes AR mRNA and protein were not significantly different between the T-H or sham group with or without FTM treatment.

CONCLUSIONS

These findings collectively suggest that, in addition to blockade of androgen receptors, flutamide-mediated ER upregulation is likely to play a role in mediating the salutary effect of flutamide on cardiac function after trauma hemorrhage.

Mechanism of salutary effects of estradiol on organ function after trauma-hemorrhage: upregulation of heme oxygenase

A growing body of evidence indicates that heme degradation products may counteract the deleterious consequences of hypoxia and/or ischemia-reperfusion injury. Because heme oxygenase (HO)-1 induction after adverse circulatory conditions is known to be protective, and because females in the proestrus cycle (with high estrogen) have better hepatic function and less hepatic damage than males after trauma-hemorrhage, we hypothesized that estrogen administration in males after trauma-hemorrhage will upregulate HO activity and protect the organs against dysfunction and injury. To test this hypothesis, male Sprague-Dawley rats underwent 5-cm laparotomy and hemorrhagic shock (35–40 mmHg for 93 ± 2 min), followed by resuscitation with four times the shed blood volume in the form of Ringer lactate. 17β-Estradiol and/or the specific HO enzyme inhibitor chromium mesoporphyrin (CrMP) were administered at the end of resuscitation, and the animals were killed 24 h thereafter. Trauma-hemorrhage reduced cardiac output, myocardial contractility, and serum albumin levels. Portal pressure and serum alanine aminotransferase levels were markedly increased under those conditions. These parameters were significantly improved in the 17β-estradiol-treated rats. Estradiol treatment also induced increased HO-1 mRNA expression, HO-1 protein levels, and HO enzymatic activity in cardiac and hepatic tissue compared with vehicle-treated trauma-hemorrhage rats. Administration of the HO inhibitor CrMP prevented the estradiol-induced attenuation of shock-induced organ dysfunction and damage. Thus the salutary effects of estradiol administration on organ function after trauma-hemorrhage are mediated in part via upregulation of HO-1 expression and activity.

Sex hormones modulate distant organ injury in both a trauma/hemorrhagic shock model and a burn model

BACKGROUND

Emerging data suggest a gender dimorphism in resistance and susceptibility to distant organ injury after mechanical and thermal trauma. The aim of this study was to determine the role that testosterone and estradiol play in modulating resistance or susceptibility to distant organ injury, and whether their effects were associated with differences in the production of nitric oxide.

METHODS

Adult male, female, castrated male, and ovariectomized female Sprague-Dawley rats were given intraperitoneal pentobarbital sodium anesthesia and subjected to trauma/sham shock or trauma/hemorrhagic shock (T/HS). A second set of animals were subjected to a 40% total body surface area, third-degree burn or sham burn. At 3 hours after resuscitation, plasma levels of nitrite/nitrate were measured, and the extent of lung injury (permeability to Evans Blue dye and neutrophil sequestration by myeloperoxidase) and intestinal injury (morphology) were determined.

RESULTS

Proestrus females showed resistance to lung and gut injury after both T/HS and burns, and had low levels of nitrite/nitrate production. This resistance to injury was abrogated by ovariectomy with an associated increase in nitric oxide production. Males showed increased lung and gut injury after both T/HS and burns associated with increased production of nitrite/nitrate. Castration decreased susceptibility to both lung and gut injury, and decreased production of nitrite/nitrate. A correlation was noted between intestinal and lung injury, and both intestinal and lung injury correlated with plasma nitrite/nitrate levels.

CONCLUSIONS

Male sex hormones potentiate, while female hormones reduce T/HS and burn-induced lung and gut injury. Production of nitric oxide is associated with increased lung and gut injury after T/HS and burns.

Estradiol's effect on portal response to endothelin-1 after trauma-hemorrhage

BACKGROUND

The fine balance between vasoconstrictors and vasodilators maintains portal circulation. Studies have shown that portal response to endothelin-1 (ET-1), a potent vasoconstrictor, is enhanced following hemorrhagic-shock, which subsequently leads to the impaired hepatic circulation and hepatic damage. Although protective effects of 17beta-estradiol (E(2)) against hepatic damage following trauma-hemorrhage have been observed, it remains unknown whether E(2) directly improves hepatic circulation. We hypothesized that the salutary effects of E(2) are mediated, at least in part, by the attenuation of portal response to ET-1 following trauma-hemorrhage.

MATERIALS AND METHODS

Male adult Sprague-Dawley rats were randomly assigned to sham operation or trauma-hemorrhage with or without in vivo E(2) treatment. Trauma-hemorrhage included midline laparotomy and approximately 90 min of hemorrhagic shock (35 mmHg), then resuscitation with four times the shed blood volume with Ringer's lactate solution over 60 min. For the E(2) treatment group, 1 mg/kg of E(2) was added to the Ringer's lactate solution. At 5 h after the end of resuscitation, the liver was isolated and perfused in vitro to measure portal pressure responses to exogenous ET-1 (60 pmol in 150 ml perfusate, bolus) with or without E(2) (1,500 pg/ml).

RESULTS

Peak portal pressure after the administration of ET-1 was significantly higher in vehicle-treated trauma-hemorrhage group compared with the sham group. This effect was significantly attenuated in the E(2) treatment group. Furthermore, E(2) treatment restored bile production and prevented hepatic damage following trauma-hemorrhage.

CONCLUSIONS

The beneficial effects of estradiol observed following trauma-hemorrhage, at least partly, are caused by the attenuation of portal pressure response to increased ET-1.

Enhanced isolated pancreatic islet recovery and functionality in rats by 17beta-estradiol treatment of brain death donors

BACKGROUND

Current isolation techniques recover only 20% to 50% of the pancreatic islets. Brain death (BD) is characterized by activation of proinflammatory cytokines (PICs) with reduced islet yields and functionality. We previously reported that 17beta-estradiol (E2) induces cytoprotection to human islets exposed to PICs. Furthermore, inhibition of PIC release has been demonstrated after E2 treatment. In the present study, we evaluated if E2 treatment to BD donors would improve pancreatic islet recovery and functionality.

METHODS

BD was induced in male, 250- to 350-g Lewis rats by inflation of a Fogarty catheter placed intracranially. Rats were mechanically ventilated for 6 hours. Only rats with mean arterial blood pressure > 75 mm Hg were used. Animals (n = 6) received E2 (1 mg/kg/iv immediately after BD induction), vehicle (V), or the combination of 17beta-estradiol and a selective estrogen receptor antagonist ICI 182,780 (ICI, 3 mg/kg/ip/1 hour before BD induction). Islet viability was determined by ethidium bromide-acridine orange. PICs were assessed by ELISA. Islet functionality was determined by static incubation and glucose disposal rate (Kg) after intraportal transplantation (3000 islet equivalent[IEQ]/syngeneic streptozotocin-induced diabetic rat).

RESULTS

A 2- to 3-fold reduction in TNF-alpha, IL-1beta, and IL-6 was demonstrated in BD donors given E2; this effect reversed by ICI 182,780. Pancreatic sections from control BD donors presented 26.5% +/- 4% TUNEL-positive beta-cells compared with 15.1% +/- 3% in 17beta-estradio-treated animals. Islet recovery was enhanced in E2-treated donors (1233.4 +/- 123 IEQ/pancreas) compared with controls (725 +/- 224 IEQ, P < .05). Islet viability was significantly enhanced by E2. Higher islet functionality was demonstrated in vitro and in vivo after transplantation in islets recovered from E2-treated BD donors.

CONCLUSIONS

Islet recovery and functionality in vitro and in vivo were significantly improved by 17beta-estradiol treatment to BD donors. These observations may lead to strategies to reduce the effects of BD on isolated islets and improve the results in clinical islet transplantation.