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

Sex disparities in adverse outcomes after surgically managed isolated traumatic spinal injury

BACKGROUND

Traumatic spinal injury (TSI) encompasses a wide range of injuries affecting the spinal cord, nerve roots, bones, and soft tissues that result in pain, impaired mobility, paralysis, and death. There is some evidence suggesting that women may have different physiological responses to traumatic injury compared to men; therefore, this study aimed to investigate if there are any associations between sex and adverse outcomes following surgically managed isolated TSI.

METHODS

Using the 2013-2019 TQIP database, all adult patients with isolated TSI, defined as a spine AIS ≥ 2 with an AIS ≤ 1 in all other body regions, resulting from blunt force trauma requiring spinal surgery, were eligible for inclusion in the study. The association between the sex and in-hospital mortality as well as cardiopulmonary and venothromboembolic complications was determined by calculating the risk ratio (RR) after adjusting for potential confounding using inverse probability weighting.

RESULTS

A total of 43,756 patients were included. After adjusting for potential confounders, female sex was associated with a 37% lower risk of in-hospital mortality [adjusted RR (95% CI): 0.63 (0.57-0.69), p < 0.001], a 27% lower risk of myocardial infarction [adjusted RR (95% CI): 0.73 (0.56-0.95), p = 0.021], a 37% lower risk of cardiac arrest [adjusted RR (95% CI): 0.63 (0.55-0.72), p < 0.001], a 34% lower risk of deep vein thrombosis [adjusted RR (95% CI): 0.66 (0.59-0.74), p < 0.001], a 45% lower risk of pulmonary embolism [adjusted RR (95% CI): 0.55 (0.46-0.65), p < 0.001], a 36% lower risk of acute respiratory distress syndrome [adjusted RR (95% CI): 0.64 (0.54-0.76), p < 0.001], a 34% lower risk of pneumonia [adjusted RR (95% CI): 0.66 (0.60-0.72), p < 0.001], and a 22% lower risk of surgical site infection [adjusted RR (95% CI): 0.78 (0.62-0.98), p < 0.032], compared to male sex.

CONCLUSION

Female sex is associated with a significantly decreased risk of in-hospital mortality as well as cardiopulmonary and venothromboembolic complications following surgical management of traumatic spinal injuries. Further studies are needed to elucidate the cause of these differences.

Anemia Recovery After Lung Contusion, Hemorrhagic Shock, and Chronic Stress Is Gender-Specific in a Rat Model

Background: Severe trauma and hemorrhagic shock lead to persistent anemia. Although biologic gender is known to modulate inflammatory responses after critical illness, the impact of gender on anemia recovery after injury remains unknown. The aim of this study was to identify gender-specific differences in anemia recovery after critical illness. Materials and Methods: Male and proestrus female Sprague-Dawley rats (n = 8-9 per group) were subjected to lung contusion and hemorrhagic shock (LCHS) or LCHS with daily chronic stress (LCHS/CS) compared with naïve. Hematologic data, bone marrow progenitor growth, and bone marrow and liver gene transcription were analyzed on day seven. Significance was defined as p < 0.05. Results: Males lost substantial weight after LCHS and LCHS/CS compared with naïve males, while female LCHS rats did not compared with naive counterparts. Male LCHS rats had a drastic decrease in hemoglobin from naïve males. Male LCHS/CS rats had reduced colony-forming units-granulocyte, -erythrocyte, -monocyte, -megakaryocyte (CFU-GEMM) and burst-forming unit-erythroid (BFU-E) when compared with female counterparts. Naïve, LCHS, and LCHS/CS males had lower serum iron than their respective female counterparts. Liver transcription of BMP4 and BMP6 was elevated after LCHS and LCHS/CS in males compared with females. The LCHS/CS males had decreased expression of bone marrow pro-erythroid factors compared with LCHS/CS females. Conclusions: After trauma with or without chronic stress, male rats demonstrated increased weight loss, substantial decrease in hemoglobin level, dysregulated iron metabolism, substantial suppression of bone marrow erythroid progenitor growth, and no change in transcription of pro-erythroid factors. These findings confirm that gender is an important variable that impacts anemia recovery and bone marrow dysfunction after traumatic injury and shock in this rat model.

State-of-the-Art Review: Sex Hormone Therapy in Trauma-Hemorrhage

ABSTRACT

Trauma-hemorrhage is the leading cause of prehospital and early in-hospital deaths, while also significantly contributing to the later development of multisystem organ dysfunction/failure and sepsis. Common and advanced resuscitative methods would potentially demonstrate benefits in the prehospital setting; however, they face a variety of barriers to application and implementation. Thus, a dialogue around a novel adjunct has arisen, sex hormone therapy. Proposed candidates include estradiol and its derivatives, metoclopramide hydrochloride/prolactin, dehydroepiandrosterone, and flutamide; with each having demonstrated a range of salutary effects in several animal model studies. Several retrospective analyses have observed a gender-based dimorphism in mortality following trauma-hemorrhage, thus suggesting that estrogens contribute to this pattern. Trauma-hemorrhage animal models have shown estrogens offer protective effects to the cardiovascular, pulmonary, hepatic, gastrointestinal, and immune systems. Additionally, a series of survival studies utilizing 17α-ethinylestradiol-3-sulfate, a potent, water-soluble synthetic estrogen, have demonstrated a significant survival benefit and beneficial effects on cardiovascular function. This review presents the findings of retrospective clinical studies, preclinical animal studies, and discusses how and why 17α-ethinylestradiol-3-sulfate should be considered for investigation within a prospective clinical trial.

Estrogens in Hepatocellular Carcinoma: Friends or Foes?

Simple Summary

Today, we know that estrogen hormones are required for the development and function of many organs, such as the liver, in both males and females. However, in some circumstances, estrogen excess may be implicated in the appearance of various chronic diseases, including cancer. This review will inspect the results of several studies to better understand the mechanisms responsible for estrogens to change from protective into harmful hormones in human liver.

Abstract

Estrogens are recognized as key players in physiological regulation of various, classical and non-classical, target organs, and tissues, including liver development, homeostasis, and function. On the other hand, multiple, though dispersed, experimental evidence is highly suggestive for the implication of estrogen in development and progression of hepatocellular carcinoma. In this paper, data from our own studies and the current literature are reviewed to help understanding this apparent discrepancy.

Early outcomes following trauma related to sex: A matched analysis of military service members in the department of defense trauma registry

BACKGROUND

Several studies have identified sex as a factor influencing early outcomes after trauma. With the increased representation of women in combat roles, there is a need for improved understanding of the pathophysiology of traumatic injury in women. The purpose of this study was to define sex-based differences in early combat trauma outcomes amongst military service members.

METHODS

A retrospective review of the Department of Defense Trauma Registry between 2008 and 2016 was performed. A 2:1 case control match was performed to match for Injury Severity Score, mechanism of injury, and age. The primary outcome of the study was mortality.

RESULTS

A total of 4,625 patients were included in the study, 2.2% of whom were women. Women were less significantly injured than men (Injury Severity Score, 7.7 vs. 11, p = 0.003) and more likely to sustain blunt trauma (81% vs. 62.5%, p = 0.01). After case-control matching, 202 men and 101 women were evaluated. There was no statistical difference in the primary outcome of mortality. There was no statistical difference in Glasgow Coma Scale score, crystalloid or colloid administration, Packed Red Blood Cells (PRBC), platelet, cryoprecipitate, or plasma usage between men and women.

CONCLUSION

Contrary to the civilian trauma literature, our study demonstrated no significant difference in early mortality between male and female combat casualties in a matched cohort. This finding may represent a difference in injury patterns, resuscitation practices, or lifesaving interventions in a deployed setting as compared with civilian setting. As the proportion of women involved in combat operations continues to increase, prospective studies should be performed to better define injury patterns, as well as early and late outcomes related to military trauma in the female population.

LEVEL OF EVIDENCE

Retrospective, Level IV.

Gender differences in trauma, shock and sepsis

Despite efforts in prevention and intensive care, trauma and subsequent sepsis are still associated with a high mortality rate. Traumatic injury remains the main cause of death in people younger than 45 years and is thus a source of immense social and economic burden. In recent years, the knowledge concerning gender medicine has continuously increased. A number of studies have reported gender dimorphism in terms of response to trauma, shock and sepsis. However, the advantageous outcome following trauma-hemorrhage in females is not due only to sex. Rather, it is due to the prevailing hormonal milieu of the victim. In this respect, various experimental and clinical studies have demonstrated beneficial effects of estrogen for the central nervous system, the cardiopulmonary system, the liver, the kidneys, the immune system, and for the overall survival of the host. Nonetheless, there remains a gap between the bench and the bedside. This is most likely because clinical studies have not accounted for the estrus cycle. This review attempts to provide an overview of the current level of knowledge and highlights the most important organ systems responding to trauma, shock and sepsis. There continues to be a need for clinical studies on the prevailing hormonal milieu following trauma, shock and sepsis.

Mitochondrial targeting by dichloroacetate improves outcome following hemorrhagic shock

Hemorrhagic shock is a leading cause of death in people under the age of 45 and accounts for almost half of trauma-related deaths. In order to develop a treatment strategy based on potentiating mitochondrial function, we investigated the effect of the orphan drug dichloroacetate (DCA) on survival in an animal model of hemorrhagic shock in the absence of fluid resuscitation. Hemorrhagic shock was induced in rats by withdrawing 60% of the blood volume and maintaining a hypotensive state. The studies demonstrated prolonged survival of rats subjected to hemorrhagic injury (HI) when treated with DCA. In separate experiments, using a fluid resuscitation model we studied mitochondrial functional alterations and changes in metabolic networks connected to mitochondria following HI and treatment with DCA. DCA treatment restored cardiac mitochondrial membrane potential and tissue ATP in the rats following HI. Treatment with DCA resulted in normalization of several metabolic and molecular parameters including plasma lactate and p-AMPK/AMPK, as well as Ach-mediated vascular relaxation. In conclusion we demonstrate that DCA can be successfully used in the treatment of hemorrhagic shock in the absence of fluid resuscitation; therefore DCA may be a good candidate in prolonged field care following severe blood loss.

Local inflammation in fracture hematoma: results from a combined trauma model in pigs

Background. Previous studies showed significant interaction between the local and systemic inflammatory response after severe trauma in small animal models. The purpose of this study was to establish a new combined trauma model in pigs to investigate fracture-associated local inflammation and gain information about the early inflammatory stages after polytrauma. Material and Methods. Combined trauma consisted of tibial fracture, lung contusion, liver laceration, and controlled hemorrhage. Animals were mechanically ventilated and under ICU-monitoring for 48 h. Blood and fracture hematoma samples were collected during the time course of the study. Local and systemic levels of serum cytokines and diverse alarmins were measured by ELISA kit. Results. A statistical significant difference in the systemic serum values of IL-6 and HMGB1 was observed when compared to the sham. Moreover, there was a statistical significant difference in the serum values of the fracture hematoma of IL-6, IL-8, IL-10, and HMGB1 when compared to the systemic inflammatory response. However a decrease of local proinflammatory concentrations was observed while anti-inflammatory mediators increased. Conclusion. Our data showed a time-dependent activation of the local and systemic inflammatory response. Indeed it is the first study focusing on the local and systemic inflammatory response to multiple-trauma in a large animal model.

Gender dimorphism of the cardiac dysfunction in murine sepsis: signalling mechanisms and age-dependency

Development of cardiac dysfunction is associated with increased morbidity and mortality in patients with sepsis. Increasing evidence shows that gender determines the degree of inflammatory response of the host and that females tolerate sepsis better than males. It is unknown whether gender affects the cardiac dysfunction in animals or patients with sepsis. To investigate this, male or female C57BL/6 mice were subjected to either lipopolysaccharide (LPS)/peptidoglycan (PepG) co-administration or cecal ligation and puncture (CLP). At 18 hours after LPS/PepG injection or 24 hours after CLP, cardiac function was evaluated by echocardiography. The septic insult caused a significant cardiac dysfunction in both genders. However, the cardiac dysfunction was significantly less pronounced in females in comparison with males subjected to LPS (3 mg/kg)/PepG (0.1 mg/kg) or CLP. Compared with males injected with LPS (3 mg/kg)/PepG (0.1 mg/kg), western blotting analysis of the myocardium from females injected with LPS/PepG revealed i) profound increases in phosphorylation of Akt and eNOS; ii) significant decreases in phosphorylation of IκBα, nuclear translocation of the NF-κB subunit p65, decreased expression of iNOS and decreased synthesis of TNF-α and IL-6 in the heart. However, the gender dimorphism of the cardiac dysfunction secondary to LPS/PepG was not observed when higher doses of LPS (9 mg/kg)/PepG (1 mg/kg) were used. In conclusion, the cardiac dysfunction caused by sepsis was less pronounced in female than in male mice. The protection of female hearts against the dysfunction associated with sepsis is (at least in part) attributable to cardiac activation of the Akt/eNOS survival pathway, decreased activation of NF-κB, and decreased expression of iNOS, TNF-α and IL-6. It should be noted that the observed gender dimorphism of the cardiac dysfunction in sepsis was not seen when a very severe stimulus (high dose of LPS/PepG co-administration) was used to cause cardiac dysfunction.

Both castration and goserelin acetate ameliorate myocardial ischemia reperfusion injury and apoptosis in male rats

Although reperfusion of an ischemic organ is essential to prevent irreversible tissue damage, it may amplify tissue injury. This study investigates the role of endogenous testosterone in myocardial ischemia reperfusion and apoptosis in male rats. Material and method. Twenty four male rats were randomized into 4 equal groups: Group (1), sham group, rats underwent the same anesthetic and surgical procedure as the control group except for LAD ligation; Group (2), Active control group, rats underwent LAD ligation; Group (3), castrated, rats underwent surgical castration, left 3wks for recovery, and then underwent LAD ligation; and Group (4), Goserelin acetate treated, rats received 3.6 mg of Goserelin 3 wks before surgery and then underwent LAD ligation. At the end of experiment, plasma cTn I, cardiac TNF-α, IL1-β, ICAM-1, and Apoptosis level were measured and histological examination was made. Results. Compared to sham group, the levels of myocardial TNF-α, IL-1β, ICAM-1, apoptosis, and plasma cTn I were significantly increased (P < 0.05) in control group and all rats showed significant myocardial injury (P < 0.05). Castration and Goserelin acetates significantly counteract the increase in myocardial levels of TNF-α, IL-1β, ICAM-1, plasma cTn I, and apoptosis (P < 0.05) and significantly reduce (P < 0.05) the severity of myocardial injury. We conclude that castration and Goserelin acetates ameliorate myocardial I/R injury and apoptosis in rats via interfering with inflammatory reactions.

Estradiol In Vivo Induces Changes in Cardiomyocytes Size in Obese Rats

We studied the in vivo effects of estradiol on size and biochemical parameters of cardiomyocytes in pathophysiological conditions such as obesity and insulin resistance. Male Wistar rats were normally fed (controls, n = 7) or fed with high-fat diet (obese, n = 14). Half of the obese rats (obese + estradiol, n = 7) were treated with a single dose of estradiol (40 μg/kg, intraperitoneally) and 24 hours after treatment all the rats were killed. Estradiol in vivo in obese rats resulted in a significant increase in protein kinase B (Akt) activation ( P < .05) and decrease in heart mass ( P < .05), ratio of the heart mass/body mass ( P < .05), transverse diameters of cardiomyocytes ( P < .001), concentration of serum high-sensitivity C-reactive protein ( P < .001), and total cholesterol ( P < .01) compared with obese nontreated rats. Our results suggest that estradiol in obese/IR rats affects the size of cardiomyocytes and its actions lead in vivo to a reduction in obesity-induced cardiac hypertrophy, via Akt.

Insulin alleviates posttrauma cardiac dysfunction by inhibiting tumor necrosis factor-α-mediated reactive oxygen species production

OBJECTIVE

Clinical evidence indicates that intensive insulin treatment prevents the incidence of multiple organ failures in surgical operation and severe trauma, but the mechanisms involved remain elusive. This study was designed to test the hypothesis that insulin may exert anti-inflammatory and antioxidative effects and thus alleviate cardiac dysfunction after trauma.

DESIGN

Prospective, randomized experimental study.

SETTING

Animal research laboratory.

SUBJECTS

Sprague Dawley rats.

INTERVENTIONS

Anesthetized rats were subjected to 200 revolutions at a rate of 35 rpm in Noble-Collip drum to induce a nonlethal mechanical trauma and were randomized to receive vehicle, insulin, and insulin + wortmannin treatments. An in vitro study was performed on cultured cardiomyocytes subjected to sham-traumatic serum (SS), traumatic serum (TS), SS + tumor necrosis factor (TNF)-α, SS + H2O2, TS + neutralizing anti-TNF-α antibody, or TS + tempol treatments.

MEASUREMENTS AND MAIN RESULTS

Immediate cardiac dysfunction occurred 0.5 hr after trauma without significant cardiomyocyte necrosis and apoptosis, while serum TNF-α and cardiac reactive oxygen species (ROS) production was increased. Importantly, incubation of cardiomyocytes with TS or SS + TNF-α significantly increased ROS generation together with dampened cardiomyocyte contractility and Ca transient, all of which were rescued by TNF-α antibody. Administration of insulin inhibited TNF-α and ROS overproduction and alleviated cardiac dysfunction 2 hours after trauma. Scavenging ROS with tempol also attenuated cardiac dysfunction after trauma, whereas insulin combined with tempol failed to further improve cardiac functional recovery compared with insulin treatment alone. Moreover, the aforementioned anti-TNF-α, antioxidative, and cardioprotective effects afforded by insulin were almost abolished by the phosphatidylinositol 3-kinase inhibitor wortmannin.

CONCLUSIONS

These results demonstrate for the first time that mechanical trauma induces a significant increase in TNF-α and ROS production, resulting in immediate cardiac dysfunction. Early posttrauma insulin treatment alleviates cardiac dysfunction by inhibiting TNF-α-mediated ROS production via a phosphatidylinositol 3-kinase/Akt-dependent mechanism.

Impaired exercise capacity and skeletal muscle function in a mouse model of pulmonary inflammation

Pulmonary TNFα has been linked to reduced exercise capacity in a subset of patients with moderate to severe chronic obstructive pulmonary disease (COPD). We hypothesized that prolonged, high expression of pulmonary TNFα impairs cardiac and skeletal muscle function, and both contribute to exercise limitation. Using a surfactant protein C promoter-TNFα construct, TNFα was overexpressed throughout life in mouse lungs (SP-C/TNFα+). TNFα levels in wild-type (WT) female serum and lung were two- and threefold higher than in WT male mice. In SP-C/TNFα+ mice, TNFα increased similarly in both sexes. Treadmill exercise was impaired only in male SP-C/TNFα+ mice. While increases in lung volume and airspace size induced by TNFα were comparable in both sexes, pulmonary hypertension along with lower body and muscle mass were evident only in male mice. Left ventricular (LV) function (cardiac output, stroke volume, LV maximal pressure, and LV maximal pressure dP/dt) was not altered by TNFα overexpression. Fatigue measured in isolated soleus and EDL was more rapid only in soleus of male SP-C/TNFα+ mice and accompanied by a loss of oxidative IIa fibers, citrate synthase activity, and PGC-1α mRNA and increase in atrogin-1 and MuRF1 expression also only in male mice. In situ gastrocnemius fatigue resistance, reflecting both oxygen availability and contractility, was decreased similarly in female and male SP-C/TNFα+ mice. These data indicate that male, but not female, mice overexpressing pulmonary TNFα are susceptible to exercise limitation, possibly due to muscle wasting and loss of the oxidative muscle phenotype, with protection in females possibly due to estrogen.

Estrogen and the cardiovascular system

Estrogen is a potent steroid with pleiotropic effects, which have yet to be fully elucidated. Estrogen has both nuclear and non-nuclear effects. The rapid response to estrogen, which involves a membrane associated estrogen receptor(ER) and is protective, involves signaling through PI3K, Akt, and ERK 1/2. The nuclear response is much slower, as the ER-estrogen complex moves to the nucleus, where it functions as a transcription factor, both activating and repressing gene expression. Several different ERs regulate the specificity of response to estrogen, and appear to have specific effects in cardiac remodeling and the response to injury. However, much remains to be understood about the selectivity of these receptors and their specific effects on gene expression. Basic studies have demonstrated that estrogen treatment prevents apoptosis and necrosis of cardiac and endothelial cells. Estrogen also attenuates pathologic cardiac hypertrophy. Estrogen may have great benefit in aging as an anti-inflammatory agent. However, clinical investigations of estrogen have had mixed results, and not shown the clear-cut benefit of more basic investigations. This can be explained in part by differences in study design: in basic studies estrogen treatment was used immediately or shortly after ovariectomy, while in some key clinical trials, estrogen was given years after menopause. Further basic research into the underlying molecular mechanisms of estrogen's actions is essential to provide a better comprehension of the many properties of this powerful hormone.

Mechanism of salutary effects of astringinin on rodent hepatic injury following trauma-hemorrhage: Akt-dependent hemeoxygenase-1 signaling pathways

Astringinin can attenuate organ injury following trauma-hemorrhage, the mechanism remains unknown. Protein kinase B/hemeoxygenase-1 (Akt/HO-1) pathway exerts potent anti-inflammatory effects in various tissues. The aim of this study is to elucidate whether Akt/HO-1 plays any role in astringinin-mediated attenuation of hepatic injury following trauma-hemorrhage. For study this, male Sprague-Dawley rats underwent trauma-hemorrhage (mean blood pressure 35–40 mmHg for 90 min) followed by fluid resuscitation. A single dose of astringinin (0.3 mg/kg body weight) with or without a PI3K inhibitor (wortmannin) or a HO antagonist (chromium-mesoporphyrin) was administered during resuscitation. Various parameters were measured at 24 h post-resuscitation. Results showed that trauma-hemorrhage increased plasma aspartate and alanine aminotransferases (AST and ALT) concentrations and hepatic myeloperoxidase activity, cytokine induced neutrophil chemoattractant (CINC)-1, CINC-3, intercellular adhesion molecule-1, and interleukin-6 levels. These parameters were significantly improved in the astringinin-treated rats subjected to trauma-hemorrhage. Astringinin treatment also increased hepatic Akt activation and HO-1 expression as compared with vehicle-treated trauma-hemorrhaged rats. Co-administration of wortmannin or chromium-mesoporphyrin abolished the astringinin-induced beneficial effects on post-resuscitation pro-inflammatory responses and hepatic injury. These findings collectively suggest that the salutary effects of astringinin administration on attenuation of hepatic injury after trauma-hemorrhage are likely mediated via Akt dependent HO-1 up-regulation.

Role of estrogen receptor-dependent upregulation of P38 MAPK/heme oxygenase 1 in resveratrol-mediated attenuation of intestinal injury after trauma-hemorrhage

Resveratrol protects against organ injury caused by trauma-hemorrhage, although the mechanism remains unknown. We have previously shown that it exerts protective effects in the liver via estrogen receptors and their signaling. Thus, we set out to determine whether resveratrol-mediated estrogen receptor-dependent p38 mitogen-activated protein kinase (MAPK)/heme oxygenase 1 activation protects the intestine after trauma-hemorrhage. To study this, male Sprague-Dawley rats underwent trauma-hemorrhage (mean blood pressure, ~ 40 mmHg for 90 min) followed by fluid resuscitation. Animals were pretreated with an estrogen receptor antagonist (ICI 182,780), a specific p38 MAPK inhibitor (SB-203580), or a heme oxygenase enzyme antagonist (chromium-mesoporphyrin) 30 min before vehicle or resveratrol (30 mg/kg) administration, followed by resuscitation, and were killed 2 h thereafter. Intestinal water content, myeloperoxidase activity, and TNF-α, IL-6, intercellular adhesion molecule 1, cytokine-induced neutrophil chemoattractant (CINC) 1, and CINC-3 levels and edema of the lung were measured. Mean arterial blood pressure, cardiac output, positive maximal pressure of left ventricular increase (+dP/dtmax), and negative maximal pressure of left ventricular decrease (-dP/dtmax) were also determined. Intestinal p38 MAPK activity and heme oxygenase 1 expression were also determined. Trauma-hemorrhage led to an increase in intestinal water content, myeloperoxidase activity, and TNF-α, IL-6, intercellular adhesion molecule 1, CINC-1, and CINC-3 levels. This was accompanied by a decrease in intestinal p38 MAPK activity. Administration of resveratrol improved all of the above parameters. Resveratrol treatment also increased intestinal heme oxygenase 1 expression as compared with vehicle-treated trauma-hemorrhaged rats. Administration of ICI 182,780, SB-203850, or chromium-mesoporphyrin with resveratrol abolished the resveratrol-mediated improvement of the above parameters. Resveratrol administration also attenuated trauma-hemorrhage-induced cardiac dysfunction and edema of the lung. These results suggest that estrogen receptor-dependent upregulation of the p38 MAPK/heme oxygenase 1 pathway plays a critical role in mediating the salutary effects of resveratrol on shock-induced intestinal injury.

Role of Akt-dependent up-regulation of hemeoxygenase-1 in resveratrol-mediated attenuation of hepatic injury after trauma hemorrhage

BACKGROUND

Protein kinase B (Akt) is known to be involved in pro-inflammatory and chemotactic events in response to injury. Akt activation also leads to the induction of hemeoxygenase (HO)-1, which exerts potent anti-inflammatory effects. The aim of this study is to elucidate whether Akt/HO-1 plays any role in resveratrol-mediated attenuation of hepatic injury after trauma hemorrhage.

METHODS

Male Sprague-Dawley rats were subjected to trauma hemorrhage. A single dose of resveratrol (30-mg/kg body weight) with or without a PI3 K inhibitor (wortmannin) or an HO antagonist (chromium-mesoporphyrin) was administered intravenously during resuscitation. Various parameters were measured at 24 hours postresuscitation.

RESULTS

Results showed that trauma hemorrhage increased hepatic myeloperoxidase activity, cytokine-induced neutrophil chemoattractant (CINC)-1, CINC-3, intercellular adhesion molecule-1, and interleukin-6 levels and plasma aspartate and alanine aminotransferases concentrations. These parameters were significantly improved in the resveratrol-treated rats subjected to trauma hemorrhage. Resveratrol treatment also increased hepatic Akt activation and HO-1 expression as compared with vehicle-treated trauma hemorrhaged rats. Coadministration of wortmannin or chromium-mesoporphyrin prevented the beneficial effects of resveratrol administration on postresuscitation proinflammatory responses and hepatic injury.

CONCLUSION

These findings collectively suggest that the salutary effects of resveratrol administration on attenuation of hepatic injury after trauma hemorrhage are likely mediated via up-regulation of Akt-dependent HO-1 expression.

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

Mechanisms of sex differences in TNFR2-mediated cardioprotection

BACKGROUND

TNFR1/TNFR2 signaling may mediate different cellular and molecular responses (injury versus protection) and the balance may be affected by sex hormones. Previous studies have shown that females have improved myocardial functional recovery, TNFR1 signaling resistance, and increased SOCS3 expression after acute ischemia/reperfusion when compared with males. However, it is unknown whether the TNFR2 pathway protects the myocardium from ischemia/reperfusion injury, and if so, whether sex differences exist in TNFR2-mediated cardioprotection. Therefore, we hypothesized that (1) TNFR2 mediates myocardial protection from ischemia/reperfusion through STAT3, SOCS3, and vascular endothelial growth factor in both sexes; and (2) TNFR2 elicits greater protective signaling in females compared with males.

METHODS AND RESULTS

Isolated male and female mouse hearts from TNFR2 knockout, TNFR1/2 knockout, and wild-type (C57BL/6J or B6129SF2/J; n=5 to 6/group) were subjected to 20 minutes ischemia followed by 60 minutes reperfusion. TNFR2 deficiency decreased postischemic myocardial recovery in both sexes but had a greater effect on females. The deleterious effects of TNFR2 ablation were associated with a decrease in mRNA and protein levels of SOCS3, STAT3, and vascular endothelial growth factor as well as an increase in myocardial interleukin-1-beta production in female hearts. However, a significant increase in JNK activation and interleukin-1-beta protein levels was noted in male TNFR2KO hearts after ischemia/reperfusion. Additionally, TNFR1/2 knockout decreased myocardial function in female hearts but not males. This observation was associated with a decrease in mRNA levels of SOCS3, STAT3, and vascular endothelial growth factor and an increase in myocardial p38 mitogen-activated protein kinase activation in females.

CONCLUSIONS

Sex differences in the mechanisms of TNFR2-mediated cardioprotection occur by increasing STAT3, SOCS3, and vascular endothelial growth factor in females and by decreasing JNK in males.

The effects of estrogen on pulmonary artery vasoreactivity and hypoxic pulmonary vasoconstriction: potential new clinical implications for an old hormone

BACKGROUND AND OBJECTIVES

Recent research recognizes gender as a major factor determining the outcomes in trauma, ischemia/reperfusion, shock, and sepsis. In particular, estrogen has been demonstrated to exert protective effects in these settings. The effects of estrogens on the pulmonary vasculature are potent and complex yet not fully understood. A better mechanistic understanding may allow for future therapeutic interventions in pulmonary hypertensive crises after cardiac surgery and during acute lung injury as well as in patients with pulmonary arterial hypertension.

DATA SOURCES AND STUDY SELECTION

We searched PubMed for articles in the English language by using the search words pulmonary hypertension, hypoxic pulmonary vasoconstriction, estrogen, estradiol, inflammation, acute injury, ischemia reperfusion, sepsis, trauma, and burns. These were used in various combinations. We read the abstracts of the relevant titles to confirm their relevance, and the full articles were then extracted. References from extracted articles were checked for any additional relevant articles.

DATA EXTRACTION AND SYNTHESIS

Estrogen plays a critical role in the improved outcomes in the settings of trauma, shock, sepsis, myocardial ischemia/reperfusion, and acute lung injury. Several new mechanisms of action have been identified. In the pulmonary vasculature, estrogen causes vasodilation and attenuates the vasoconstrictor response to various stimuli, including hypoxia. This is mediated by increased levels of prostacyclin and nitric oxide as well as decreased levels of endothelin-1. In addition, effects on intracellular signaling pathways and several kinases as well as anti-inflammatory mechanisms may contribute as well. Recent studies suggest the importance of acute, nongenomic effects.

CONCLUSION

Estrogen exerts a variety of nongenomic actions, which may allow for future therapeutic interventions in pulmonary vascular disease.

Selective inhibition of iNOS attenuates trauma-hemorrhage/resuscitation-induced hepatic injury

Although trauma-hemorrhage produces tissue hypoxia, systemic inflammatory response and organ dysfunction, the mechanisms responsible for these alterations are not clear. Using a potent selective inducible nitric oxide (NO) synthase inhibitor, N-[3-(aminomethyl) benzyl]acetamidine (1400W), and a nonselective NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME), we investigated whether inducible NO synthase plays any role in producing hepatic injury, inflammation, and changes of protein expression following trauma-hemorrhage. To investigate this, male Sprague-Dawley rats were subjected to midline laparotomy and hemorrhagic shock (mean blood pressure 35-40 mmHg for approximately 90 min) followed by fluid resuscitation. Animals were treated with either vehicle (DMSO) or 1400W (10 mg/kg body wt ip), or L-NAME (30 mg/kg iv), 30 min before resuscitation and killed 2 h after resuscitation. Trauma-hemorrhage/resuscitation induced a marked hypotension and increase in markers of hepatic injury (i.e., plasma alpha-glutathione S-transferase, tissue myeloperoxidase activity, and nitrotyrosine formation). Hepatic expression of iNOS, hypoxia-inducible factor-1alpha, ICAM-1, IL-6, TNF-alpha, and neutrophil chemoattractant (cytokine-induced neutrophil chemoattractant-1 and macrophage inflammatory protein-2) protein levels were also markedly increased following trauma-hemorrhage/resuscitation. Administration of the iNOS inhibitor 1400W significantly attenuated hypotension and expression of these mediators of hepatic injury induced by trauma-hemorrhage/resuscitation. However, administration of L-NAME could not attenuate hepatic dysfunction and tissue injury mediated by trauma-hemorrhage, although it improved mean blood pressure as did 1400W. These results indicate that increased expression of iNOS following trauma-hemorrhage plays an important role in the induction of hepatic damage under such conditions.

The role of estrogen receptor subtypes on hepatic neutrophil accumulation following trauma-hemorrhage: direct modulation of CINC-1 production by Kupffer cells

Although 17beta-estradiol (E2) administration following trauma-hemorrhage (T-H) reduces liver injury by decreasing neutrophil accumulation via estrogen receptor (ER)-alpha, it remains unclear whether cytokine-induced neutrophil chemoattractant (CINC)-1 production by Kupffer cells (KC) is directly modulated by ER-alpha under such condition. Male rats underwent laparotomy and hemorrhagic shock (40 mmHg for 90 min), followed by resuscitation with four times the shed blood volume in the form of Ringer's lactate. ER-alpha agonist propyl pyrazole triol (PPT; 5 microg/kg), ER-beta agonist diarylpropionitrile (DPN; 5 microg/kg), E2 (50 microg/kg), or vehicle (10% DMSO) was administered subcutaneously during resuscitation; rats were sacrificed 24h thereafter. KC were isolated and cultured with ER agonists to examine if they directly affect CINC-1 production. T-H increased plasma alanine aminotransferase (ALT; hepatic injury) and hepatic myeloperoxidase (MPO) activity. E2, PPT and DPN administration reduced increased ALT; however, PPT was more effective than DPN. PPT and E2, but not DPN significantly attenuated increased hepatic MPO activity and CINC-1 levels. PPT addition in vitro (10(-7) and 10(-6)M) significantly reduced KC CINC-1 production. In summary, the salutary effects of E2 against hepatic injury are mediated predominantly via ER-alpha which directly modulates KC CINC-1 production and hepatic neutrophil accumulation following T-H.

Trauma and immune response--effect of gender differences

A major consequence of traumatic injury is immunosuppression. Findings from previous studies suggest that the depression of immune functions is severe in young males, ovariectomised and aged females. In contrast, the immune functions in proestrus females following trauma-haemorrhage are maintained. Studies have also shown that the survival rate in proestrus females following trauma-haemorrhage and the induction of subsequent sepsis is significantly higher than in age-matched males and ovariectomised females. Furthermore, administration of female sex hormone 17beta-oestradiol in males and ovariectomised females after trauma-haemorrhage prevents the suppression of immune response. Thus, these findings suggest that sex hormones play a significant role in shaping the host response following trauma. This article reviews studies delineating the mechanism by which sex hormones regulate immune cell functions in the experimental model of trauma-haemorrhage. The findings from the studies reviewed in this article suggest that sex steroids can be synthesised by the immune cell. The findings further indicate that T cell and macrophages express receptors for androgen and oestrogen. Since these cells are also the cells that produce cytokines, local synthesis of active steroids in these cells may become the significant factor in modulating their cytokine production.

In the adult mesenchymal stem cell population, source gender is a biologically relevant aspect of protective power

BACKGROUND

Acute treatment with bone marrow mesenchymal stem cells (MSC) reduces myocardial infarct size by multiple mechanisms, including the paracrine release of protective growth factors. Female MSCs produce more growth factor when stressed; therefore, we hypothesized that myocardial protection provoked by female MSCs would be greater than that elicited by male MSCs.

METHODS

Hearts were subjected to 25 min of warm global ischemia, 40 min of reperfusion, and randomly assigned into one of three groups: (1) vehicle treated; (2) male MSC treated; and (3) female MSC treated. Myocardial function was continuously recorded and in separate experiments, male and female MSC growth factor production was assessed by ELISA.

RESULTS

All indices of functional recovery were significantly higher in the stem cell infused rat heart compared with control hearts. Interestingly, female MSC treated rat hearts demonstrated significantly greater recovery of left ventricular developed pressure, +dP/dT, and -dP/dT than male MSC treated hearts at end reperfusion. In addition, male MSCs produced significantly greater tumor necrosis factor alpha, and significantly less vascular endothelial growth factor than female MSCs.

CONCLUSIONS

This study is the first to demonstrate that, in the adult mesenchymal population, source gender is a biologically relevant aspect of ultimate stem cell function in the heart.

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.

Mechanism of estrogen-mediated attenuation of hepatic injury following trauma-hemorrhage: Akt-dependent HO-1 up-regulation

Protein kinase B (Akt) is known to be involved in proinflammatory and chemotactic events in response to injury. Akt activation also leads to the induction of heme oxygenase (HO)-1. Up-regulation of HO-1 mediates potent, anti-inflammatory effects and attenuates organ injury. Although studies have shown that 17beta-estradiol (E2) prevents organ damage following trauma-hemorrhage, it remains unknown whether Akt/HO-1 plays any role in E2-mediated attenuation of hepatic injury following trauma-hemorrhage. To study this, male rats underwent trauma-hemorrhage (mean blood pressure, approximately 40 mmHg for 90 min), followed by fluid resuscitation. At the onset of resuscitation, rats were treated with vehicle, E2 (1 mg/kg body weight), E2 plus the PI-3K inhibitor (Wortmannin), or the estrogen receptor (ER) antagonist (ICI 182,780). At 2 h after sham operation or trauma-hemorrhage, plasma alpha-GST and hepatic tissue myeloperoxidase (MPO) activity, IL-6, TNF-alpha, ICAM-1, cytokine-induced neutrophil chemoattractant-1, and MIP-2 levels were measured. Hepatic Akt and HO-1 protein levels were also determined. Trauma-hemorrhage increased hepatic injury markers (alpha-GST and MPO activity), cytokines, ICAM-1, and chemokine levels. These parameters were markedly improved in the E2-treated rats following trauma-hemorrhage. E2 treatment also increased hepatic Akt activation and HO-1 expression compared with vehicle-treated, trauma-hemorrhage rats, which were abolished by coadministration of Wortmannin or ICI 182,780. These results suggest that the salutary effects of E2 on hepatic injury following trauma-hemorrhage are in part mediated via an ER-related, Akt-dependent up-regulation of HO-1.

The role of estrogen receptor subtypes in ameliorating hepatic injury following trauma-hemorrhage

BACKGROUND/AIMS

The aim of this study was to determine which of the estrogen receptor (ER) subtypes plays a predominant role in ameliorating hepatic damage following trauma-hemorrhage.

METHODS

Adult male rats were subjected to hemorrhagic shock (40 mmHg for 90 min) and resuscitation. ER-alpha agonist (PPT) or ER-beta agonist (DPN) was administered during resuscitation; rats were sacrificed 24h thereafter.

RESULTS

PPT or DPN decreased elevated plasma alpha-glutathione S-transferase levels; however, PPT was more effective. PPT or DPN increased hepatic heat shock protein 32 (Hsp32) mRNA/protein expressions above levels observed after trauma-hemorrhage. PPT reduced hepatic NF-kappaB and AP-1 activity and iNOS expression. Although DPN reduced hepatic NF-kappaB activity, AP-1 activity remained higher than in shams; hepatic iNOS induction remained elevated. PPT/DPN reduced nitrate/nitrite production and iNOS mRNA in Kupffer cells following trauma-hemorrhage; however, these levels in DPN-treated animals remained higher than sham.

CONCLUSIONS

Although both PPT and DPN decreased hepatic injury following trauma-hemorrhage, ER-alpha agonist PPT appears to be more effective in downregulating NF-kappaB and AP-1 activity, and iNOS induction. Thus, ER-alpha appears to play a predominant role in mediating the salutary effects of E2 in ameliorating hepatic damage following trauma-hemorrhage.

The protective effects of 17beta-estradiol on hepatic ischemia-reperfusion injury in rat model, associated with regulation of heat-shock protein expression

BACKGROUND

Ischemia-reperfusion (I/R) injury, which was commonly seen in the field of hepatic surgical intervention, impaired liver regeneration and predisposed to liver failure. Previous studies have shown gender dimorphic response of the liver for various hepatic stresses including I/R injury, hemorrhagic shock-resuscitation, liver cirrhosis, endotoxemia, and chronic alcoholic consumption, and demonstrated gender dimorphism in hepatocellular dysfunction after experimental trauma and hemorrhage. The objective of this study was to examine the hypothesis that the protective effects of 17beta-estradiol (E2) in hepatic I/R injury were associated with increasing heat-shock protein 70 expression.

MATERIALS AND METHODS

Sprague-Dawley male and female rats were randomly divided into male and female sham, I/R, and E2 + I/R groups. The model of reduced-size liver ischemia and reperfusion was used. Except for the sham-operated groups, all rats were subjected to 70% liver ischemia for 45 min followed by resection of the remaining 30% nonischemic lobes and reperfusion of ischemic tissue. For each group, five rats were used to investigate the survival during a week after operation; blood samples and liver tissues were obtained in the remaining animals after 3, 12, and 24 h of reperfusion to assess serum alanine aminotransferase, aspartate aminotransferase, liver tissue NO(2)(-) + NO(3)(-), malondialdehyde content, superoxide dismutase, nitric oxide synthase, and myeloperoxidase activity, Hsp70 expression, and apoptosis ratio.

RESULTS

Compared with I/R groups, male and female E2 + I/R groups showed less I/R-induced injury, and SOD and eNOS activity and Hsp70 expression were increased significantly (P < 0.01). A higher rate of apoptosis was observed in the I/R group versus the E2 + I/R group, a significant increase of MDA, NO(2)(-) + NO(3)(-), and MPO of liver tissues and serum transaminase were also observed in the I/R group versus the E2 + I/R group. The survival rate was significantly higher in the male E2 + I/R group than in the male I/R group.

CONCLUSION

E2 pretreatment had protective effects on liver in hepatic I/R injury. The mechanism of this protection might be related to overexpression of Hsp70.

Sex dimorphisms in activated mesenchymal stem cell function

The plasticity of bone marrow-derived stem cells (BMSCs) has resulted in positive remodeling and the regeneration of viable tissues. However, BMSC release of growth factors, which limit apoptosis and inflammation, may play an important role in conferring organ protection. Recent studies also indicate that those patients with higher circulating BMSC counts may be more resistant to septic and traumatic insults. There are clear sex differences in response to such insults. Within the population of BMSC, mesenchymal stem cells (MSCs) may have clinical advantages. Therefore, we hypothesize that sex differences in the MSC paracrine response to acute injury exist. Mesenchymal stem cells were obtained from male and female mice. One million MSCs per well (triplicate wells per group) were stressed by hypoxia and increasing doses of endotoxin (lipopolysaccharide [LPS]) and hydrogen peroxide. Mesenchymal stem cell activation was determined by measuring vascular endothelial growth factor (VEGF) and tumor necrosis factor alpha production by enzyme-linked immunosorbent assay. Differences were considered significant if P < 0.05.

RESULTS

Lipopolysaccharide resulted in significant activation of both male and female MSCs. However, LPS provoked significantly more VEGF production in female MSCs versus male MSCs at all LPS doses. Hypoxia of 1 h and hydrogen pyroxide exposure also caused significantly more VEGF production in female MSCs versus male MSCs. Female MSCs expressed significantly less tumor necrosis factor alpha than male MSCs after acute LPS and hypoxia.

CONCLUSION

This study constitutes the first demonstration that sex differences exist in activated MSC function. Sex differences in progenitor cell function may have important implications in understanding the observed sex differences in the host's response to injury.

Gender differences in injury induced mesenchymal stem cell apoptosis and VEGF, TNF, IL-6 expression: role of the 55 kDa TNF receptor (TNFR1)

Concomitant pro- and anti-inflammatory properties of bone marrow stem cells (BMSC) may be an important aspect of their ability to heal injured tissue. However, very few studies have examined whether gender differences exist in BMSC function. Indeed, it remains unknown whether gender differences exist in BMSC function and ability to resist apoptosis, and if so, whether TNF receptor 1 (TNFR1) plays a role in these differences. We hypothesized that TNFR1 ablation equalizes gender differences in bone marrow mesenchymal stem cell (MSC) apoptosis, as well as expression of vascular endothelial growth factor (VEGF), TNF and interleukin (IL)-6. Mouse MSCs from male wild type (WT), female WT, male TNFR1 knockouts (TNFR1KO) and female TNFR1KO were stressed by endotoxin 200 ng/ml or 1 h hypoxia. MSC activation was determined by measuring VEGF, TNF and IL-6 production (ELISA). Differences considered significant if p<0.05. LPS and hypoxia resulted in significant activation in all experimental groups compared to controls. Male WT demonstrated significantly greater TNF and IL-6 and significantly less VEGF release than female WT MSCs. However, release of TNF, IL-6 and VEGF in male TNFR1 knockouts differed from male WT, but was not different from female WT MSCs. Similarly apoptosis in hypoxic male TNFRIKO differed from male WT, but it was not different from apoptosis from WT female. Female WT did not differ in TNF, IL-6 and VEGF release compared to female TNFR1KO. Gender differences exist in injury induced BMSC VEGF, TNF and IL-6 expression. TNFR1 may autoregulate VEGF, TNF and IL-6 expression in males more than females. MSCs are novel therapeutic agents for organ protection, but further study of the disparate expression of VEGF, TNF and IL-6 in males and females as well as the role of TNFR1 in these gender differences is necessary to maximize this protection.

Jak/STAT/SOCS signaling circuits and associated cytokine-mediated inflammation and hypertrophy in the heart

Cytokines are important mediators of cardiac disease. Accumulating evidence indicates that members of the interleukin-6 family of cytokines promote cardiac hypertrophy through the activation of the Janus kinase-signal transducer and activator of transcription (Jak/STAT) pathway. Aberrant Jak/STAT signaling may promote progression from hypertrophy to heart failure. Suppressor of cytokine signaling (SOCS) proteins are underexplored, negative regulators of Jak/STAT signaling. SOCS proteins may also interact with other inflammatory pathways known to affect cardiac function. A better understanding of the therapeutic potential of these proteins may lead to the controlled progression of heart failure and the limitation of myocardial depression. This review summarizes the cardiophysiological effect of the IL-6 cytokine family, outlines the mechanistic pathway of Jak/STAT signaling, explores the regulatory role of SOCS proteins in the heart, and discusses the potential of using SOCS proteins clinically.