Dehydroepiandrosterone restores depressed peripheral blood mononuclear cell function following major abdominal surgery via the estrogen receptors

Effect of Patient Sex on Neurocognitive Decline after Cardiac Surgery

BACKGROUND

Neurocognitive decline (NCD) is a common complication of cardiac surgery. Understanding risk factors helps surgeons counsel patients pre- and perioperatively about risk, prevention, and treatment.

STUDY DESIGN

Patients undergoing cardiac surgery using cardiopulmonary bypass underwent pre- and postoperative neurocognitive testing. Neurocognitive data are presented as a change from baseline to either postoperative day 4 or to 1 month. The score is standardized with respect to age.

RESULTS

Eighty-four patients underwent surgery and completed postoperative neurocognitive testing. There was no significant difference in baseline neurocognitive function. NCD was more common in female patients (71%) than male patients (26.4%) on postoperative day 4. By 1 month, the incidence of NCD is similar between female (15.0%) and male patients (14.3%). Of note, female patients differed from male patients in preoperative hematocrit, preoperative creatinine, and type of surgery.

CONCLUSIONS

In the acute postoperative period, female patients are both more likely to experience NCD and experience a more severe change from baseline cognitive function. This difference between male and female patients resolves by the 1 month follow-up point. Female patients had a lower preoperative hematocrit and were more likely to receive intraoperative and perioperative blood transfusion. Lower preoperative hematocrit appears to mediate the difference in NCD between male and female patients.

The Roles of Sex Hormones in the Course of Atopic Dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by T helper 2 cell (Th2)-shifted abnormal immunity, skin barrier impairment, and pruritus. The prevalence of AD in childhood is slightly higher in boys than in girls; after puberty, the sexual difference is reversed. The female preponderance in all generations exists in intrinsic AD with enhanced Th1 activity and nickel allergy, lacking increased serum IgE or filaggrin mutation. AD is often deteriorated before menstruation. We review the effects of sex hormones on immune responses and skin permeability barrier and propose possible hypotheses for the above phenomena. After puberty, the immune responses of patients are remarkably influenced by sex hormones. Estrogen and progesterone enhance the activities of Th2/regulatory T cell (Treg) but suppress Th1/Th17. Androgens suppress Th1/Th2/Th17 and induce Treg. The skin permeability barrier is fortified by estrogen but is impaired by progesterone and androgens. Dehydroepiandrosterone suppresses Th2 but enhances Th1. The amount of steroid sulfatase converting dehydroepiandrosterone sulfate to dehydroepiandrosterone is higher in women than in men, and thus, women might be more susceptible to the influence of dehydroepiandrosterone. The balance of modulatory effects of sex hormones on immune responses and skin barrier might regulate the course of AD.

Dehydroepiandrosterone improves the ovarian reserve of women with diminished ovarian reserve and is a potential regulator of the immune response in the ovaries

Diminished ovarian reserve (DOR) has a high morbidity rate worldwide and has become a primary cause of infertility. DOR is a daunting obstacle in in vitro fertilization (IVF) and leads to poor ovarian response, high cancellation rates, poor IVF outcomes, and low pregnancy rates. Abnormal autoimmune function may also contribute to DOR. Dehydroepiandrosterone (DHEA) is a C19 androgenic steroid. DHEA is secreted mainly by the adrenal gland, and its secretion declines with age. DHEA has a pro-inflammatory immune function that opposes cortisol. The cortisol to DHEA ratio increases with age, which may lead to decreased immune function. DHEA supplementation helps improve this situation. A number of clinical case control studies and several prospective randomized clinical trials have observed a positive effect of DHEA supplementation in women with DOR. However, the underlying mechanism by which DHEA improves ovarian reserve remains unclear. DHEA functions as an immune regulator in many different tissues in mammals and may also play an important role in regulating the immune response in the ovaries. The conversion of DHEA to downstream sex steroids may allow it to regulate the immune response there. DHEA can also enhance the Th1 immune response and regulate the balance of the Th1/Th2 response. DHEA treatment can increase selective T lymphocyte infiltration in mice, resulting in a decline in the CD4+ T lymphocyte population and an upregulation of the CD8+ T lymphocyte population in ovarian tissue, thus regulating the balance of CD4+/CD8+ T cells. This review mainly focuses on how DHEA supplementation affects regulation of the immune response in the ovaries.

Gender-Specific Effects on Immune Response and Cardiac Function after Trauma Hemorrhage and Sepsis

Background

Studies in human as well as animal models indicate a gender-specific responsiveness of the immune and organ systems with regard to shock, trauma, and sepsis.

Methods

A literature review was performed.

Results

Cell-mediated immune responses and cardiovascular functions are suppressed in males following trauma hemorrhage, whereas they are maintained or even enhanced in females in the proestrus state of the estrus cycle. Experimental studies have demonstrated that divergent immune responses in males and females following adverse circulatory conditions are mediated by the gender-specific hormones testosterone and estrogen. Several clinical trials, however, failed to demonstrate a significant association of gender and inflammatory response. This may be explained by the heterogeneity of the population in terms of their hormonal status at the time of injury.

Conclusions

With regard to the underlying mechanisms, receptors for sex hormones have been identified on various immune cells, suggesting direct effects of these hormones on immune function. Alternatively, indirect effects of sex steroids such as changes in cardiovascular responses or androgen- and estrogen-synthesizing enzymes might contribute to gender-specific immune responses. Clinical studies suggest that sex hormones, such as dehydroepiandrosterone, modulate the function of peripheral blood mononuclear cells also following abdominal surgery. Thus, sex hormones, receptor antagonists, and sex steroid-synthesizing enzymes might be useful in the future for modulating the complex immune responses after trauma hemorrhage and sepsis.

Potential therapeutic targets for sepsis in women

INTRODUCTION

Gender is increasingly recognized as a key factor in trauma and sepsis. Multiple clinical and experimental studies on sepsis have shown a distinct advantage of females in the proestrus cycle to survive sepsis compared with age-matched males. In addition, estrogen treatment is beneficial in non-proestrus cycles and also in ovarectomized females. In this manuscript, the effects of gender and sex hormones in sepsis are summarized and potential gender-specific therapeutic strategies in women are evaluated.

AREAS COVERED

This review comprises current clinical studies on the effect of gender in sepsis and gives an overview on gender and sex hormone-related effects on immune cells and organ function. Based on clinical and experimental data, potential therapeutic targets are presented.

EXPERT OPINION

Estrogens and estrogen-receptor agonists have been extensively shown to be beneficial in the setting of sepsis. Clinical data, however, do not clearly support their therapeutic use. This discrepancy appears to be mainly due to insufficient study design in clinical trials conducted up to now. Therefore, improved study protocols with exact analysis of the patients' hormonal status are needed to clarify the role of gender and sex hormones in trauma and sepsis.

Suppressive effects of androgens on the immune system

Sex-based disparities in immune responses are well known phenomena. The two most important factors accounting for the sex-bias in immunity are genetics and sex hormones. Effects of female sex hormones, estrogen and progesterone are well established, however the role of testosterone is not completely understood. Evidence from unrelated studies points to an immunosuppressive role of testosterone on different components of the immune system, but the underlying molecular mechanisms remains unknown. In this review we evaluate the effect of testosterone on key cellular components of innate and adaptive immunity. Specifically, we highlight the importance of testosterone in down-regulating the systemic immune response by cell type specific effects in the context of immunological disorders. Further studies are required to elucidate the molecular mechanisms of testosterone-induced immunosuppression, leading the way to the identification of novel therapeutic targets for immune disorders.

Gender differences in sepsis: cardiovascular and immunological aspects

During sepsis, a complex network of cytokine, immune, and endothelial cell interactions occur and disturbances in the microcirculation cause organ dysfunction or even failure leading to high mortality in those patients. In this respect, numerous experimental and clinical studies indicate sex-specific differences in infectious diseases and sepsis.

Female gender has been demonstrated to be protective under such conditions, whereas male gender may be deleterious due to a diminished cell-mediated immune response and cardiovascular functions. Male sex hormones, i.e., androgens, have been shown to be suppressive on cell-mediated immune responses. In contrast, female sex hormones exhibit protective effects which may contribute to the natural advantages of females under septic conditions. Thus, the hormonal status has to be considered when treating septic patients.

Therefore, potential therapies could be derived from this knowledge. In this respect, administration of female sex hormones (estrogens and their precursors) may exert beneficial effects. Alternatively, blockade of male sex hormone receptors could result in maintained immune responses under adverse circulatory conditions. Finally, administration of agents that influence enzymes synthesizing female sex hormones which attenuate the levels of pro-inflammatory agents might exert salutary effects in septic patients. Prospective patient studies are required for transferring those important experimental findings into the clinical arena.

The battle of the sexes: women win out in gastrointestinal surgery

BACKGROUND

Women have been shown to have worse outcomes compared with men after cardiac surgery, but fare better after traumatic injury. No study considers the impact of gender on outcomes after major gastrointestinal surgery. We hypothesize that the physiologic insults of a major abdominal operation are similar to an injury model; therefore, women will have improved outcomes.

MATERIAL AND METHODS

We performed a retrospective review of the NIS database from 1998 to 2007. Patients undergoing major gastrointestinal surgery were identified by ICD-9 procedure codes: esophageal (42.4), gastric (43.5-43.9), small intestine (45.6), large intestine (45.7-45.8 and 17.3), rectal (48.4-48.6), hepatic (50.2-50.3), biliary (51.3 and 51.6), and pancreatic (52.5-52.7). Exclusion criteria included age over 60 y and under 18 y, multiple operations, and a sexual developmental disorder (25.52, 75.27, and 25.9). The primary outcome measure was in-hospital death.

RESULTS

A total of 307,124 patients were identified, of whom 50.3% were women. Overall, there were 6574 (2.14%) deaths; 2.45% of men and 1.84% of women died (P < 0.001). In multivariate analysis, women were 21.1% less likely to die than men (OR = 0.789, 95% CI = 0.74-0.84). When subset analysis was performed, women had improved mortality in the following types of surgery: gastric (OR = 0.751, 95% CI = 0.60-0.94), small intestine (OR = 0.704, 95% CI = 0.63-0.79), large intestine (OR = 0.845, 95% CI = 0.77--0.93), hepatic (OR = 0.562, 95% CI = 0.41-0.77), and pancreatic (OR = 0.658, 95% CI = 0.49-0.89, see Fig. 1).

CONCLUSIONS

Our study demonstrates that women may have improved outcomes after some types of major gastrointestinal surgery; however, the mechanism by which this occurs is unclear. Future studies are needed to further evaluate this interesting phenomenon.

New insights into the protective effects of DHEA1)

Numerous studies investigated the effects of pharmacological doses of DHEA in animals. Among protective effects, antiglucocorticoid potencies, triggering and modulation of immunity and anticancerous effects were reported. Because DHEA levels decrease in aging humans, this steroid has been assayed as replacement therapy in elderly volunteers without striking evidence for beneficial effects. Examination of the investigations carried out in animals lead to suspect that, rather than DHEA, its metabolites produced in tissues could be responsible for some of the observed effects. Known as the "mother steroid", DHEA is a precursor for androgenic and estrogenic steroid hormones. In addition, DHEA is hydroxylated at the 7α position by the cytochrome P450 7B1 (CYP7B1), and the 7α-hydroxy-DHEA produced is a substrate for the 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) which converts it into 7β-hydroxy-DHEA. Both 7-hydroxylated metabolites were shown to favor the onset of immunity in mice and the activation of memory T cells in humans. Other DHEA and testosterone-derived metabolites, namely epiandrosterone and 5α-androstane-3β,17β-diol, are also substrates for the CYP7B1 and their 7α-hydroxylated products were also converted into the 7β epimer by the 11β-HSD1. When assayed at doses 104 lower than DHEA, 7β-hydroxy-epiandrosterone was shown to shift the prostaglandin metabolism patterns from prostaglandin E2 (PGE2) to PGD2 production, thus triggering the resolution of inflammation. In addition, 7β-hydroxy-epiandrosterone (1 nM) exerted the same effects as tamoxifen (1 μM) on the proliferation of MCF-7 and MDA-231 human breast cancer cells. These findings suggest that the observed effects of 7β-hydroxy-epiandrosterone could be mediated by estrogen receptors. This overview of recent research implies that DHEA does not act directly and that its effects are due to its metabolites when produced in tissues. Treatments with DHEA should take into account the target tissue abilities to produce the desired metabolites through the two key enzymes, CYP7B1 and 11β-HSD1.

Dehydroepiandrosterone sulfate directly activates protein kinase C-beta to increase human neutrophil superoxide generation

Dehydroepiandrosterone sulfate (DHEAS) is the most abundant steroid in the human circulation and is secreted by the adrenals in an age-dependent fashion, with maximum levels during the third decade and very low levels in old age. DHEAS is considered an inactive metabolite, whereas cleavage of the sulfate group generates dehydroepiandrosterone (DHEA), a crucial sex steroid precursor. However, here we show that DHEAS, but not DHEA, increases superoxide generation in primed human neutrophils in a dose-dependent fashion, thereby impacting on a key bactericidal mechanism. This effect was not prevented by coincubation with androgen and estrogen receptor antagonists but was reversed by the protein kinase C inhibitor Bisindolylmaleimide 1. Moreover, we found that neutrophils are unique among leukocytes in expressing an organic anion-transporting polypeptide D, able to mediate active DHEAS influx transport whereas they did not express steroid sulfatase that activates DHEAS to DHEA. A specific receptor for DHEAS has not yet been identified, but we show that DHEAS directly activated recombinant protein kinase C-beta (PKC-beta) in a cell-free assay. Enhanced PKC-beta activation by DHEAS resulted in increased phosphorylation of p47(phox), a crucial component of the active reduced nicotinamide adenine dinucleotide phosphate complex responsible for neutrophil superoxide generation. Our results demonstrate that PKC-beta acts as an intracellular receptor for DHEAS in human neutrophils, a signaling mechanism entirely distinct from the role of DHEA as sex steroid precursor and with important implications for immunesenescence, which includes reduced neutrophil superoxide generation in response to pathogens.

Immune perturbations in patients along the perioperative period: alterations in cell surface markers and leukocyte subtypes before and after surgery

BACKGROUND

Surgery renders patients susceptible to life-threatening complications, including infections, multiple organ failure, and presumably cancer metastases. Surgery-induced immune perturbations were suggested to contribute to such deleterious effects, but also to facilitate post-injury healing. Preoperative psychological and physiological stress responses may contribute to these immune perturbations, and could thus jeopardize patients even before surgery. The current study assessed the effects of various operations on an array of immune indices during the perioperative period. To qualify immune changes before surgery, patients' immune status was also compared to that of healthy controls.

METHODS

A total of 81 subjects (operated patients and healthy controls) provided up to five daily blood samples during the perioperative period, for assessment of leukocyte subtypes (granulocytes, monocytes, Tc, Th, NK, NKT, CD4+CD25+, CD8(bright)CD4(dim), and B cells) and their surface markers (HLA-DR and LFA-1).

RESULTS

Even before surgery patients displayed immune perturbations, including reduced lymphocyte HLA-DR expression and increased monocyte LFA-1 expression. Following surgery, we recorded a reduction in lymphocyte numbers that was subtype specific, increased granulocyte numbers, and reduced expression of HLA-DR by lymphocytes and monocytes. Finally, no significant associations were found between alteration in leukocyte numbers and cell surface markers (although these indices showed high correlations with other variables), implying differential mediating mechanisms.

CONCLUSION

Several immune alterations are manifested prior to surgery, and contribute to the marked postoperative changes, which are commonly interpreted as immune suppression. We discuss the possible adaptive and maladaptive nature of these perturbations in the context of natural injury, stress, and surgery.

Trauma sepsis

Sepsis is a major cause of mortality and morbidity in the trauma patient. Sepsis following traumatic injury is related to the type of injury, together with the extent of injury and the anatomical location. Burn injuries are associated with the highest risk of sepsis. The diagnosis of sepsis in the trauma patient remains difficult. Interpretation of abnormal results is key to successful diagnosis, particularly in conjunction with clinical findings. This review will consider the specific features of sepsis in the context of trauma relating to epidemiology, risk factors, diagnosis and management.

DHEA-dependent and organ-specific regulation of TNF-alpha mRNA expression in a murine polymicrobial sepsis and trauma model

Introduction

Dehydroepiandrosterone (DHEA) improves survival after trauma and sepsis, while mechanisms of action are not yet fully understood. Therefore, we investigated the influence of DHEA on local cytokine expression in a two-hit model.

Methods

Male NMRI mice were subjected to femur fracture/hemorrhagic shock and subsequent sepsis. Sham-operated animals were used as controls. DHEA (25 mg/kg) or vehicle was administered daily. Mortality rate, activity and body temperature were determined daily after sepsis induction. TNF-α, IL-1β and IL-10 mRNA expression pattern were investigated in lung and liver tissue after 48 and 96 hours.

Results

DHEA treatment resulted in a significantly reduced mortality rate and improvements in the clinical status. On cytokine level, only TNF-α was significantly reduced in the cecal ligation and puncture (CLP)-vehicle group in both tissues after 48 hours. This suppression could be restored by DHEA administration. In contrast, after 96 hours, TNF-α was up-regulated in the CLP-vehicle group while remaining moderate by DHEA treatment in liver tissue.

Conclusions

The improved outcome after DHEA treatment and trauma is coherent with restoration of TNF-α in liver and lung after 48 hours and a counter-regulatory attenuation of TNF-α in liver after 96 hours. Thus, DHEA seems to act, time and organ dependent, as a potent modulator of TNF-α expression.

Bench-to-bedside review: latest results in hemorrhagic shock

Hemorrhagic shock is a leading cause of death in trauma patients worldwide. Bleeding control, maintenance of tissue oxygenation with fluid resuscitation, coagulation support, and maintenance of normothermia remain mainstays of therapy for patients with hemorrhagic shock. Although now widely practised as standard in the USA and Europe, shock resuscitation strategies involving blood replacement and fluid volume loading to regain tissue perfusion and oxygenation vary between trauma centers; the primary cause of this is the scarcity of published evidence and lack of randomized controlled clinical trials. Despite enormous efforts to improve outcomes after severe hemorrhage, novel strategies based on experimental data have not resulted in profound changes in treatment philosophy. Recent clinical and experimental studies indicated the important influences of sex and genetics on pathophysiological mechanisms after hemorrhage. Those findings might provide one explanation why several promising experimental approaches have failed in the clinical arena. In this respect, more clinically relevant animal models should be used to investigate pathophysiology and novel treatment approaches. This review points out new therapeutic strategies, namely immunomodulation, cardiovascular maintenance, small volume resuscitation, and so on, that have been introduced in clinics or are in the process of being transferred from bench to bedside. Control of hemorrhage in the earliest phases of care, recognition and monitoring of individual risk factors, and therapeutic modulation of the inflammatory immune response will probably constitute the next generation of therapy in hemorrhagic shock. Further randomized controlled multicenter clinical trials are needed that utilize standardized criteria for enrolling patients, but existing ethical requirements must be maintained.

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.

Endocrine aspects of critical illness

Metabolic disorders and endocrine changes are common and relevant in critically ill patients. Thereby, endocrinopathies, electrolyte or metabolic derangements may either pre-exist or develop, and left unattended, may lead to significant morbidity and mortality. The homeostatic corrections which have emerged in the course of human evolution to cope with the catastrophic events during critical illness involve a complex multisystem endeavour, of which the endocrine contribution is an integral component. Although the repertoire of endocrine changes has been probed in some detail, discerning the vulnerabilities and failures of this system is far more challenging. The ensuing endocrine topics illustrate some of the current issues reflecting attempts to gain an improved insight and clinical outcome for critical illness. Disturbances in glucose and cortisol homeostasis during critical illness are two controversially debated topics in the current literature. The term "hormokine" encompasses the cytokine like behaviour of hormones during inflammation and infections. The concept is based on an ubiquitous expression of calcitonin peptides during sepsis. Adrenomedullin, another member of the calcitonin peptide superfamily, was shown to complement and improve the current prognostic assessment in lower respiratory tract infections. Procalcitonin is the protopye of "hormokine" mediators circulating procalcitonin levels increase several 10,000-fold during sepsis improve the clinical assessment especially of respiratory tract infections and sepsis safely and markedly reduces antibiotic usage in non-bacterial respiratory tract infections and meningitis. Adrenomedullin, another member of the calcitonin peptide superfamily, was shown to complement and improve the current prognostic assessment in lower respiratory tract infections. Hormokines are not only biomarkers of infection. Hormokines are also pivotal inflammatory mediators. Like all mediators, their role during systemic infections is basically beneficial, possibly to combat invading microbes. Yet, with increasing levels they can become harmful for their host. Multiple mechanisms of action were proposed. In several animal models the modulation and neutralization of hormokines during infection was shown to improve survival and thus might open new treatment options for severe infections, especially of the respiratory tract.

Immune response of severely injured patients--influence of surgical intervention and therapeutic impact

BACKGROUND

[corrected] Severe injury leads to a severe deterioration of the patients' immune response. The changes of the immune response after severe injury include a broad range of immune functions and may result in a status of immunosuppression, which could favor infectious complications. Therefore, immunostimulating therapies have been introduced in the therapy for severely injured patients in clinical and experimental settings.

OBJECTIVES

The article summarizes actual immunomodulating approaches in the treatment of trauma patients and therapeutic strategies avoiding additional immune deteriorations.

RESULTS

Examples for an immunostimulating approach in trauma patients are interferon gamma and the granulocyte macrophage-colony-stimulating factor (GM-CSF), which are summarized in this review in detail. However, the effect of such an interference in the patients' immune response with all its different cellular targets is not yet clearly understood, and most studies focus on the reaction of circulating monocytes. In addition, further immunomodulating strategies, including nutritional support, are addressed. However, clinically established therapeutic immunomodulating strategies in trauma care so far do not exist. The impact of the accidental and also an additional surgical trauma on the immune response has been clearly demonstrated. Therefore, the idea of a "damage control orthopedic surgery" (DCOS) is not only necessary to prevent further deterioration of the homeostasis of, e.g., the coagulating system, but is also desirable in terms of minimizing the burden on the immune system. In addition, also the timing of secondary surgical treatment in trauma patient care should include an evaluation of the immune response, although the most reliable markers still need to be identified.

CONCLUSION

Immunomodulating therapies in trauma patients exist on an experimental level with inconsistent results. The general management of trauma patients includes strategies that have been developed also on the basis of immunological considerations.

The hypothalamic-pituitary-adrenal axis in critical illness

The hypothalamic-pituitary-adrenal response to stress is a dynamic process. The homeostatic corrections that have emerged in the course of human evolution to cope with the catastrophic events during critical illness involve a complex multisystem endeavor. Although the repertoire of endocrine changes has been probed in some detail, discerning the vulnerabilities and failures of this system is far more challenging. One of the most controversially debated topics in the current literature is the characterization and optimal treatment of allegedly inadequate adaptations of the hypothalamic-pituitary-adrenal axis during critical illness. This outline attempts to touch briefly some of the debated issues, stir the discussion, and thereby contribute to resolving the dispute.

Androstenetriol improves survival in a rodent model of traumatic shock

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

HYPOTHESIS

The neurosteroid AET will increase survival following traumatic shock.

METHODS

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

RESULTS

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

CONCLUSION

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

Gender and sex hormones influence the response to trauma and sepsis: potential therapeutic approaches

Several clinical and experimental studies have demonstrated gender dimorphism in immune and organ responsiveness and in the susceptibility to and morbidity from shock, trauma, and sepsis. In this respect, cell-mediated immune responses have been shown to be depressed in males following trauma-hemorrhage, whereas they were aintained/enhanced in proestrus females. Furthermore, sex hormones have been shown to be responsible for this gender-specific immune response following adverse circulatory conditions. More specifically, studies indicate that androgens produce immunodepression following trauma-hemorrhage in males. In contrast, female sex steroids appear to exhibit immunoprotective properties following trauma and severe blood loss. With regard to the underlying mechanisms, receptors for sex hormones have been identified on various immune cells suggesting direct effects of these hormones on the immune cells. Alternatively, indirect effects of sex hormones, ie, modulation of cardiovascular responses or androgen- and estrogen-synthesizing enzymes, might contribute to gender-specific immune responses. Recent studies indicate that sex hormones, eg, dehydroepiandrosterone (DHEA), also modulate the function of peripheral blood mononuclear cells in surgical patients. Thus, the immunomodulatory properties of sex hormones/receptor antagonists/sex steroid synthesizing enzymes following trauma-hemorrhage suggests novel therapeutic strategies for the treatment of immunodepression in surgical patients.

Metformin prevents embryonic resorption induced by hyperandrogenisation with dehydroepiandrosterone in mice

The present study examined the mechanism by which metformin prevents dehydroepiandrosterone (DHEA)-induced embryonic resorption in mice. Treatment with DHEA (6 mg/100 g bodyweight, 24 and 48 h post implantation) induced 88 +/- 1 % embryonic resorption and the diminution of both serum oestradiol (E) and progesterone (P) levels. However, when metformin (50 mg/kg bodyweight) was given together with DHEA, embryo resorption (43 +/- 3% v. 35 +/- 5% in controls) and both serum E and P levels were not significantly different from controls. Glucose and insulin levels were increased in the DHEA-treated mice but when metformin was administered together with DHEA these parameters were similar to control values. Treatment with DHEA increased ovarian oxidative stress and diminished uterine nitric oxide synthase (NOS) activity; however, when metformin was administered together with DHEA, both ovarian oxidative stress and uterine NOS activity were not different from controls. Metformin treatment did not modify the percentage of CD4(+) and CD8(+) T cells from both axillar and retroperitoneal lymph nodes but prevented the increase of serum tumour necrosis factor +/- produced in DHEA-treated mice. These results show that metformin acts in DHEA-induced embryonic resorption in mice by modulating endocrine parameters, ovarian oxidative stress and uterine NOS activity.

Effect of dehydroepiandrosterone on lipopolysaccharide-induced interleukin-6 production in DH82 cultured canine macrophage cells

OBJECTIVE

This study examined the effect of dehydroepiandrosterone (DHEA) on lipopolysaccharide (LPS)-stimulated interleukin-6 (IL-6) production in the DH82 canine macrophage cell line.

STUDY DESIGN

Cultured DH82 cells were stimulated with varying concentrations of LPS with or without DHEA for various times. Supernatant IL-6 levels were measured by enzyme-linked immunosorbent assay, and cellular cytoplasmic IkappaBalpha protein expression measured by Western blot analysis.

RESULTS

LPS dose-dependently stimulated IL-6 production (p=0.016). Cells stimulated with 20 microg LPS showed a time-dependent increase of IL-6 concentration up to 10 h post-treatment (p=0.007). Co-treatment of DH82 cells with 20 microg LPS and various concentrations of DHEA for 14 h showed that up to 10 microM DHEA dose-dependently decreased the IL-6 concentration (p=0.007). Also, addition of 20 microM DHEA to DH82 cells with 20 microg LPS time-dependently decreased the IL-6 concentration for up to 14 h post-treatment (p=0.018). Stimulation of cultured DH82 cells with 20 microg LPS significantly decreased cellular cytoplasmic IkappaBalpha expression, beginning at 30 min post-treatment and persisting to at least 2 h post-treatment (p=0.012). However, co-treatment of cells with 20 microg LPS and 20 microM DHEA abrogated this effect until 2 h post-treatment.

CONCLUSIONS

DHEA decreased the IL-6 concentration in the supernatant of LPS-stimulated DH82 cells by inhibiting the sequestration of IkappaBalpha, which is necessary for the activation of nuclear factor-kappa B. These findings provide new insights into the immunomodulatory effects of DHEA.

Surgical trauma and immunosuppression: pathophysiology and potential immunomodulatory approaches

BACKGROUND

Several studies indicate that organ failure is the leading cause of death in the postoperative phase after major surgery. An excessive inflammatory response followed by a dramatic depression of cell-mediated immunity after major surgery appears to be responsible for the increased susceptibility to subsequent sepsis. In view of this, most of the scientific and medical research has been directed towards measuring the progression and interrelationship of mediators after major surgery. Furthermore, the effect of those mediators on cell-mediated immune responses has been studied.

OBJECTIVE

This article focuses on the effect of surgical injury and blood loss on cell-mediated immune responses in experimental studies utilizing models of trauma and hemorrhagic shock. The findings from those experimental studies will also be correlated with data from surgical patients.

RESULTS

Recently, a gender-dimorphic immune and organ responsiveness in the susceptibility to and morbidity from shock, trauma, and sepsis has been found. Androgens have been shown to be responsible for the immunosuppression after trauma-hemorrhage in males. In contrast, female sex steroids exhibit immunoprotective properties after trauma and severe blood loss.

CONCLUSION

In view of these findings, clinically relevant therapeutic strategies have been developed using the testosterone receptor blocker flutamide and/or estrogen or agents with estrogenic effects, i.e., dehydroepiandrosterone, which might yield safe and useful therapeutic approaches for the treatment of immune depression in surgical patients.