Endocrine-paracrine interaction in communication between the immune and endocrine systems. Activation of the hypothalamic-pituitary-adrenal axis in inflammation

Extracellular vesicles in mammalian reproduction: a review

Over the last decades, extracellular vesicles (EVs) have been found to be implicated in a complex universal mechanism of communication between different cell types. EVs are nanostructures of lipid nature that have an exosomal or ectosomal biogenesis, responsible for the intercellular transport of proteins, lipids, carbohydrates, nucleic acids, ions, among other molecules. The content of EVs can vary due to various factors such as hormonal stimuli, non-physiological conditions, metabolic state, etc. Once EVs reach their target cell, they can modulate processes such as gene expression, metabolism, response to external factors, and can even be associated with the delivery of molecules involved in epigenetic inheritance processes in germ cells. In mammalian reproduction, EVs have been shown to play an important role, either in vivo or in vitro, modulating a variety of processes in sperm, oocytes and embryos, and in their respective environments. Moreover, EVs represent a biodegradable, harmless and specific vehicle, which makes them attractive allies to consider when improving assisted reproductive technologies (ARTs). Therefore, the present review aims to describe the content of the main EVs involved in mammalian reproduction and how they can vary due to different factors, as well as to detail how EVs modulate, directly or indirectly, different molecular processes in gametes and embryos. In addition, we will highlight the mechanisms that remain to be elucidated. We will also propose new perspectives according to the characteristics of each particular EV to improve the different ARTs.

Single-cell transcriptome analysis identifies a unique tumor cell type producing multiple hormones in ectopic ACTH and CRH secreting pheochromocytoma

Ectopic Cushing’s syndrome due to ectopic ACTH&CRH-secreting by pheochromocytoma is extremely rare and can be fatal if not properly diagnosed. It remains unclear whether a unique cell type is responsible for multiple hormones secreting. In this work, we performed single-cell RNA sequencing to three different anatomic tumor tissues and one peritumoral tissue based on a rare case with ectopic ACTH&CRH-secreting pheochromocytoma. And in addition to that, three adrenal tumor specimens from common pheochromocytoma and adrenocortical adenomas were also involved in the comparison of tumor cellular heterogeneity. A total of 16 cell types in the tumor microenvironment were identified by unbiased cell clustering of single-cell transcriptomic profiles from all specimens. Notably, we identified a novel multi-functionally chromaffin-like cell type with high expression of both POMC (the precursor of ACTH) and CRH, called ACTH+&CRH + pheochromocyte. We hypothesized that the molecular mechanism of the rare case harbor Cushing’s syndrome is due to the identified novel tumor cell type, that is, the secretion of ACTH had a direct effect on the adrenal gland to produce cortisol, while the secretion of CRH can indirectly stimulate the secretion of ACTH from the anterior pituitary. Besides, a new potential marker (GAL) co-expressed with ACTH and CRH might be involved in the regulation of ACTH secretion. The immunohistochemistry results confirmed its multi-functionally chromaffin-like properties with positive staining for CRH, POMC, ACTH, GAL, TH, and CgA. Our findings also proved to some extent the heterogeneity of endothelial and immune microenvironment in different adrenal tumor subtypes.

Review: Endotoxin and the hypothalamo-pituitary-adrenal (HPA) axis

Endotoxin is considered to be a systemic (immunological) stressor eliciting a prolonged activation of the hypothalamo-pituitary-adrenal (HPA) axis. The HPA-axis response after an endotoxin challenge is mainly due to released cytokines (IL-1, IL-6 and TNF-α) from stimulated peripheral immune cells, which in turn stimulate different levels of the HPA axis. Controversy exists regarding the main locus of action of endotoxin on glucocorticoid secretion, since the effect of endotoxin on this neuro-endocrine axis has been observed in intact animals and after ablation of the hypothalamus; however, a lack of LPS effect has been described at both pituitary and adrenocortical levels. The resulting increase in adrenal glucocorticoids has well-documented inhibitory effects on the inflammatory process and on inflammatory cytokine release. Therefore, immune activation of the adrenal gland by endotoxin is thought to occur by cytokine stimulation of corticosteroid-releasing hormone (CRH) production in the median eminence of the hypothalamus, which, in turn stimulates the secretion of ACTH from the pituitary. Acute administration of endotoxin stimulates ACTH and cortisol secretion and the release of CRH and vasopressin (AVP) in the hypophysial portal blood. During repeated endotoxemia, tolerance of both immune and HPA function develops, with a crucial role for glucocorticoids in the modulation of the HPA axis. A single exposure to a high dose of LPS can induce a long-lasting state of tolerance to a second exposure of LPS, affecting the response of plasma TNF-α and HPA hormones. Although there are gender differences in the HPA response to endotoxin and IL-1, these responses are enhanced by castration and attenuated by androgen and estrogen replacement. Estrogens attenuate the endotoxin-induced stimulation of IL-6, TNF-α and IL-1ra release and subsequent activation in postmenopausal women. There appears to be a temporal and functional relation between the HPA-axis response to endotoxin and nitric oxide formation in the neuro-endocrine hypothalamus, suggesting a stimulatory role for nitric oxide in modulating the HPA response to immune challenges.

Two severe cases of H7N9 pneumonia patients with immunoneuroendocrine axis dysfunction and vitamin D insufficiency

Background

The immunoneuroendocrine axis plays a major role in the regulation of the host’s response to infection, but its role in severe H7N9 pneumonia is still unknown. Therefore, this study is carried out to explore the relationship between the immunoneuroendocrine axis and severe H7N9 pneumonia.

Case presentantion

The study included two H7N9 pneumonia patients. Endocrine response and cellular immune function in prolonged phase of these two severe H7N9 pneumonia cases were reported and analyzed. A 57-year-old male patient (case 1) and a 68-year-old male patient (case 2) were admitted because of cough, fever and dyspnea. Moist rales were present in both lungs. The rest of the examination was reportedly normal. The laboratory test showed that (1) The patients had loss of cortisol rhythm and elevated cortisol level at 4 pm. (2) The patients showed decline of cellular immune function. (3) The patients showed vitamin D insufficiency. (4) Case 2 had higher cortisol level but lower DHEAS, serum phosphorus and vitamin D level as well as cellular immune function than case 1. (5) The thyroid axis, gonadal and lactotropic axis were normal, so were the level of FT3, FT4, STSH and LH, FSH, T, E2 as well as PRL in these two cases. Chest CT revealed inflammation of both lungs especially in right lung. Real time RT-PCR by Centers for Disease Control and Prevention (CDC) confirmed H7N9 infection.

Conclusion

Immunoneuroendocrine axis dysfunction may play an important role in severe H7N9 pneumonia. We need pay more attention to hypophosphatemia and vitamin D insufficiency in H7N9 pneumonia.

Aspirin and immune system

The time-tested gradual exploration of aspirin's diverse pharmacological properties has made it the most reliable therapeutic agent worldwide. In addition to its well-argued anti-inflammatory effects, many new and exciting data have emerged regarding the role of aspirin in cells of the immune system and certain immunopathological states. For instance, aspirin induces tolerogenic activity in dendritic cells and determines the fate of naive T cells to regulatory phenotypes, which suggests its immunoregulatory potential in relevance to immune tolerance. It also displays some intriguing traits to modulate the innate and adaptive immune responses. In this article, the immunomodulatory relation of aspirin to different immune cells, such as neutrophils, macrophages, dendritic cells (DCs), natural killer (NK) cells, and the T and B lymphocytes has been highlighted. Moreover, the clinical prospects of aspirin in terms of autoimmunity, allograft rejection and immune tolerance have also been outlined.

Lipopolysaccharide stimulates adrenal steroidogenesis in rodent cells by a NFκB-dependent mechanism involving COX-2 activation

Stimulation of adrenal steroidogenesis is involved in the HPA response to exogenous noxa. Although inflammatory cytokines can mediate the LPS-triggered activation of the HPA, direct effects of LPS on glucocorticoid release have been described. Present studies were undertaken to characterize the molecular mechanisms underlying the effect of LPS on steroid secretion in isolated rodent adrenal cells, assessing the participation of NFκB and COX-2 activities in this response. Our results show that LPS treatment stimulates steroidogenesis in murine and rat adrenocortical cells, and that Y1 cells express the binding-transducing complex TLR-4/CD14/MD-2, as demonstrated by RT-PCR. NFκB activity and COX-2 protein levels are increased in this cell line by LPS treatment, and pharmacologic and molecular manipulation of the NFκB pathway significantly affected both COX-2 protein levels and steroid production. Finally, pharmacological inhibition of COX-2 activity significantly impairs steroid production. Thus, our results strongly suggest that the mechanism involved in the stimulation of steroidogenesis by LPS in rodent adrenal cells involves the activation of the NFκB signaling pathway and the induction of COX-2.

Is there a relationship between admission blood glucose level following acute poisoning and clinical outcome?

INTRODUCTION

The aim of this study was to investigate the relationship between the admission blood glucose level following acute poisoning, severity of acute poisoning and clinical outcome.

MATERIAL AND METHODS

This prospective study was conducted on 345 deliberate self-poisoning patients. Standard demographic and clinical information; admission blood glucose level; poisoning severity score and outcome were recorded. Patients with a history of diabetes mellitus, receipt of pre-sampling intravenous dextrose solution or glucocorticoids, and poisoning with toxic agents which produce hyper- or hypoglycaemia were excluded.

RESULTS

Mean age of the patients was 27.5 ±8.6 years. Females outnumbered males (57.9%). Oral ingestion of more than one drug (46.7%) and opiates (14.2%) were the main causes of poisoning. Blood glucose values ranged from 50 mg/dl to 396 mg/dl. Hyper- and hypoglycaemia were observed in 23.8% and 13.91% respectively. A total of 24.41% and 22.92% of the patients in hyper- and hypoglycaemic groups had grade 3 and 4 severity score in comparison with 4.18% in the normoglycaemic group. Development of complications and death were 14.64% and 10.42% in patients with hyper- and hypoglycaemia versus 3.73% in patients with normoglycaemia. A significant difference between normoglycaemic and hyperglycaemic patients in the severity of poisoning and clinical outcome was observed (P < 0.001).

CONCLUSIONS

Admission blood glucose levels may have a relationship with the severity of poisoning and clinical outcome following acute poisoning.

Hormonal deficiencies during and after Puumala hantavirus infection

Previous reports have described panhypopituitarism associated with severe cases of hemorrhagic fever with renal syndrome (HFRS), but the prevalence of hormonal deficiencies after nephropathia epidemica (NE), a milder form of HFRS, has not been studied. This study was conducted in order to determine the prevalence of hormonal defects in patients with acute NE and during long-term follow-up. Fifty-four patients with serologically confirmed acute NE were examined by serum hormonal measurements during the acute NE, after 3 months, and after 1 to 10 (median 5) years. Thirty out of 54 (56%) patients had abnormalities of the gonadal and/or thyroid axis during the acute NE. After a median follow-up of 5 years, 9 (17%) patients were diagnosed with a chronic, overt hormonal deficit: hypopituitarism was found in five patients and primary hypothyroidism in five patients. In addition, chronic subclinical testicular failure was found in five men. High creatinine levels and inflammatory markers during NE were associated with the acute central hormone deficiencies, but not with the chronic deficiencies. Hormonal defects are common during acute NE and, surprisingly, many patients develop chronic hormonal deficiencies after NE. The occurrence of long-term hormonal defects cannot be predicted by the severity of acute NE.

Release of melanotroph- and corticotroph-type proopiomelanocortin derivatives into blood after administration of corticotropin-releasing hormone in patients with septic shock without adrenocortical insufficiency

The aim of the study was to assess the adequacy of pituitary function by determining the plasma concentrations of corticotroph-type (corticotropin, beta-endorphin immunoreactive material [beta-END IRM], authentic beta-END, and beta-lipotropin IRM) as well as melanotroph-type (alpha-melanocyte-stimulating hormone [alpha-MSH] and N-acetyl-beta-END [Nac-beta-END] IRM) proopiomelanocortin (POMC) derivatives in patients under septic shock upon administration of corticotropin-releasing hormone (CRH). The objectives were to assess whether an insufficient release of corticotroph- or melanotroph-type POMC derivatives from the pituitary into the cardiovascular compartment correlates with the 28-day mortality rate. Seventeen patients with septic shock but without adrenocortical insufficiency and 16 healthy volunteers were enrolled in the study, and CRH stimulation tests were performed with an i.v. bolus injection of 100 microg human CRH. After treatment with CRH, plasma concentrations of corticotroph-type POMC derivatives increased in survivors and nonsurvivors, melanotroph-type POMC derivatives such as alpha-MSH or Nac-beta-END IRM increased only in survivors in contrast to nonsurvivors. The release of alpha-MSH and Nac-beta-END IRM was suppressed by dexamethasone in survivors but not in nonsurvivors. In patients with septic shock, the response of the pituitary to CRH stimulation in terms of alpha-MSH or Nac-beta-END IRM release was impaired in nonsurvivors compared with survivors or controls. Reduced responses of alpha-MSH or Nac-beta-END IRM to CRH and the invalid suppression by dexamethasone reflect a state of dysfunction of the melanotroph-type POMC system in nonsurvivors. Considering anticytokine and anti-inflammatory effects of alpha-MSH, this dysfunction may increase the risk of death in patients with septic shock.

Somatostatin infusion increases intestinal ischemia and does not improve vasoconstrictor response to norepinephrine in ovine endotoxemia

Hemodynamic support of patients with septic shock is often complicated by a tachyphylaxis against exogenous catecholamines. Because an increase in somatotropic hormones may play a pivotal role in the regulation of the inflammatory response to endotoxin, intravenous supplementation of the neuroendocrine hormone somatostatin (SOMA) may attenuate hemodynamic dysfunction resulting from endotoxemia. The objective of the present study was to assess the short-term effects of SOMA alone and in combination with norepinephrine (NE) on cardiopulmonary hemodynamics, global oxygen transport, plasma nitrate/nitrite levels, and intestinal integrity compared with single NE therapy in ovine endotoxemia. After a baseline measurement in healthy sheep (n = 16) had been performed, Salmonella typhosa endotoxin was centrally infused (10 ng x kg(-1) x min(-1)) to induce a hypotensive-hyperdynamic circulation using an established protocol. Animals surviving 16 h of endotoxemia were randomly assigned to one of the two groups (each n = 6). Sheep allocated to the SOMA + NE group received SOMA as a loading dose of 10.5 microg x kg(-1) x min(-1) for 1 h, followed by a continuous infusion of 3.5 microg x kg(-1) x min(-1) for the next 2 h. After the SOMA loading dose had been given, NE was concurrently infused (0.3 microg x kg(-1) x min(-1)) for 2 h. In the NE group (control), NE (0.3 microg x kg(-1) x min(-1)) was continuously infused for 3 h. Endotoxemia caused a decrease in MAP and systemic vascular resistance index in both groups, but to a greater extent in the NE group. Arterial hypotension persisted despite administration of the study drugs. Infusion of SOMA alone and in combination with NE did not significantly increase systemic vascular resistance index. Neither SOMA nor NE infusion alone affected pulmonary vasoregulation. Plasma nitrate/nitrite levels did not differ between groups. However, combined infusion of SOMA and NE significantly increased arterial lactate concentrations, oxygen consumption index, and oxygen extraction rate (P < 0.05) and aggravated ileal mucosal injury. In conclusion, short-term treatment with SOMA failed to attenuate cardiocirculatory shock resulting from endotoxemia and did not improve vasopressor response to NE. In addition, combined SOMA and NE therapy resulted in intestinal injury. Therefore, SOMA does not seem to represent a therapeutic option to treat arterial hypotension resulting from sepsis and systemic inflammatory response syndrome.

Insulin regulates IL-1alpha, Ifn-y and IL-4 release from murine splenocytes stimulated with staphylococcal protein A, toxic shock syndrome toxin-1 and streptococcal lysin S

In this study, changes were investigated in release of IL-1alpha, IFN-gamma and IL-4 from mouse splenocytes stimulated with staphylococcal protein A (SpA), toxic shock syndrome toxin-1 (TSST-1) or streptococcal lysin S (SLS) in the presence of insulin. The results show that insulin-treated splenocytes stimulated by SpA had a 25% increase in IFN-gamma release and a 50% decrease in IL-4 compared with splenocytes treated with SpA alone. IL-1alpha release was unchanged compared with controls. Insulintreated splenocytes stimulated with TSST-1 had a 30% fall in IL-1alpha and IFN-gamma release compared with controls. There were no changes in IL-4 release. Splenocytes stimulated with SLS after insulin treatment increased their release of IL-1alpha and IFN-gamma by 50%, whereas IL-4 release was unchanged. The data suggest that the insulin may have important functional implications in immunoregulation.

The origins of cachexia in acute and chronic inflammatory diseases

The term cachexia originates from the Greek root kakos hexis, which translates into "bad condition," recognized for centuries as a progressive deterioration of body habitus. Cachexia is commonly associated with a number of disease states, including acute inflammatory processes associated with critical illness and chronic inflammatory diseases, such as cancer, congestive heart failure, chronic obstructive pulmonary disease, and human immunodeficiency virus infection. Cachexia is responsible for the deaths of 10%-22% of all patients with cancer and approximately 15% of the trauma deaths that occur from sepsis-induced organ dysfunction and malnutrition days to weeks after the initial traumatic event. The abnormalities associated with cachexia include anorexia, weight loss, a preferential loss of somatic muscle and fat mass, altered hepatic glucose and lipid metabolism, and anemia. Anorexia alone cannot fully explain the development of cachexia; metabolic alterations in carbohydrate, lipid, and protein metabolism contribute to the severe tissue losses. Despite significant advances in our understanding of specific disease processes, the mechanisms leading to cachexia remain unclear and multifactorial. Although complex, increasing evidence from both animal models and clinical studies suggests that an inflammatory response, mediated in part by a dysregulated production of proinflammatory cytokines, plays a role in the genesis of cachexia, associated with both critical illness and chronic inflammatory diseases. These cytokines are further thought to induce an acute phase protein response (APR) and produce the alterations in lipid and carbohydrate metabolism identified as crucial markers of acute inflammation in states of malignancy and critical illness. Although much is still unknown about the etiology of cachexia, there is growing appreciation that cachexia represents the endproduct of an inappropriate interplay between multiple cytokines, neuropeptides, classic stress hormones, and intermediary substrate metabolism.

Adrenal axis functions in patients with familial Mediterranean fever

OBJECTIVE

Familial Mediterranean fever (FMF) is a hereditary disease characterized by recurrent attacks of fever with peritonitis, arthritis, pleuritis or erysipelas-like rash. It is unclear what effects of FMF itself on endocrine system and hormones are. None of the FMF patients without amyloidosis have been reported to have any endocrine disorders, except those who developed colchicine-induced diabetes insipidus. There is a large body of evidence to show that cytokines (IL-1, IL-6 and TNF-alpha) activate the hypothalamic-pituitary-adrenal (HPA) axis. We have designated this study to investigate the HPA axis in FMF patients without amyloidosis.

METHODS

Twenty-one patients with FMF were included. ACTH stimulation test was performed on the healthy subjects and during attack period in the patients. In the patient group, same test was repeated during remission period.

RESULTS

Peak cortisol levels were significantly higher in the attack period than those in the remission period of patients (p<0.05).

CONCLUSION

The cytokines play a role on the activation of the HPA axis; we thought the axis would be affected in this disease. The response of cortisol to 250 mug ACTH was significant in attack period when compared with remission period. This result reveals that HPA axis is more activated in an FMF attack. Previous studies suggest that the adrenal hormones increase in acute inflammatory events, and eventually, the changes on these hormones are related to TNF and IL-6 levels. During the FMF attack, HPA axis may be stimulated by cytokines. It seems that HPA axis is regulated normally in FMF patients.

Bacterial endotoxin induces IL-20 expression in the glial cells

The regulatory mechanisms leading to IL-20 expression during infection have not been elucidated. In the present study, we found that bacterial lipopolysaccharide (LPS) induced IL-20 expression in the primary cultured glial cells and RAW264.7 macrophage cell line. Pretreatment with protein synthesis inhibitor puromycin or cycloheximide failed to inhibit the expression of IL-20, suggesting that the expression was not dependent on de novo protein synthesis. Myeloid differentiation factor 88 (MyD88) is an important adaptor molecule for Toll-like receptor signaling. We observed complete inhibition of LPS-induced expression of IL-20 in the primary cultured glial cells prepared from MyD88-deficient mice. Furthermore, a p38 MAP kinase inhibitor, SB203580, inhibited LPS-induced expression of IL-20 mRNA. LPS-induced p38 MAP kinase phosphorylation was delayed in MyD88-deficient glial cells. Therefore, it is suggested that LPS induces IL-20 expression through MyD88-p38-dependent mechanisms. As dexamethasone inhibited LPS-induced IL-20 expression, the expression of IL-20 is regulated by a negative feedback loop mediated through glucocorticoids. Therefore, it is suggested that IL-20 may play a crucial role in inflammatory conditions in the brain.

STAT3 activation and c-FOS expression in the brain following peripheral administration of bacterial DNA

To study the role of bacterial DNA in the brain function, we investigated signal transducer and activator of transcription 3 (STAT3) activation and c-FOS expression in the brain by immunohistochemistry in response to peripheral administration of CpG-DNA. CpG-DNA induced phospho-STAT3-immunoreactive cells and c-FOS-positive cells in several brain regions in a different manner. Phospho-STAT3-immunoreactive cells were observed in the circumventricular organs where the blood-brain barrier is weak. On the other hand, CpG-DNA increased c-FOS-positive cells in the paraventricular nucleus of the hypothalamus, and the nucleus of the tractus solitarius (NTS) and the area postrema. Unilateral cervical vagotomy did not modify CpG-DNA-induced c-FOS expression in the NTS, indicating that CpG-DNA-induced activation of the NTS is independent of the afferent vagus nerve input originating from the subdiaphragmatic organs. On the other hand, Toll-like receptor 9 mRNA was expressed in the nodose ganglion. Therefore, it is possible that CpG-DNA activates afferent vagus nerve through the nodose ganglion which subsequently activates the NTS. Present observations represented that peripheral CpG-DNA induced immune event in the brain, and that not only c-FOS but also phosphorylation of STAT3 can be a useful indicator for evaluation of neuro-immune interaction.

Effect of subdiaphragmatic vagotomy on bacterial DNA-induced IL-1β expression in the mouse hypothalamus

We investigated whether bacterial DNA (CpG-DNA)-induced IL-1beta expression in the mouse hypothalamus is mediated via afferent vagus nerve. Subdiaphragmatic vagotomy did not modify the CpG-DNA (i.p.)-induced IL-1beta expression in the hypothalamus, indicating that CpG-DNA-induced IL-1beta expression is independent of the afferent vagus nerve originating from the subdiaphragmatic organs. On the other hand, we observed the Toll-like receptor 9 mRNA expression in the hypothalamus, suggesting that circulating CpG-DNA acts directly in the brain.

The immunoneuroendocrine axis in critical illness: beneficial adaptation or neuroendocrine exhaustion?

PURPOSE OF REVIEW

Over the last years, endocrinology has been incorporated in critical care medicine, and acknowledgment of the complex neuro-endocrine adaption of critical illness has led to new insights and major breakthroughs in clarifying pathophysiological mechanisms and the targeting of therapeutic strategies. This review focuses on the important role of the hypothalamic-pituitary-adrenal (HPA) axis during critical illness and the occurrence of neuroendocrine failure.

RECENT FINDINGS

The distinction between acute (activated anterior pituitary function and inactivated peripheral anabolic pathways) and prolonged (reduced neuroendocrine stimulation) critical illness as different neuroendocrine paradigms has brought a new approach to the critically ill patient. The HPA adaptation in the prolonged phase is characterized by hypercortisolism induced by non-ACTH driven pathways as ACTH levels are low. In spite of the high-normal (total) cortisol levels, HPA insufficiency appears to be quite common. On the other hand, there is a marked depletion of corticosteroid-binding globulin (CBG) in the acute phase of critical illness, resulting in increased free and biologically active cortisol. There is a persistent marked depletion of dehydroeplandrosterone sulfate, possibly indicating adrenal exhaustion, while macrophage inhibitory factor is upregulated in sepsis, affecting and contraregulating the biological effects of glucocorticoids.

SUMMARY

The endocrine system is highly interrelated with the immune and neural systems, the neuroimmunoendocrine axis is subject to clear biphasic changes in the acute and chronic phases of critical illness, most likely reflecting a beneficial adaptation. These neuroendocrine dynamics should be considered when assessing the neuroendocrine system, in particular the HPA axis.

Bacterial endotoxin induces STAT3 activation in the mouse brain

In the present study, we investigated regulatory mechanisms of bacterial endotoxin-induced STAT3 activation in the brain. Intraperitoneal injection of lipopolysaccharide (LPS) dose-dependently (0.5-5000 microg/kg) induced STAT3 phosphorylation in the hypothalamus. LPS-induced STAT3 phosphorylation was peaked at 2-4 h and declined there after. Moreover, intracerebroventricular injection of LPS induced STAT3 phosphorylation in the cortex and the hippocampus, indicating that central as well as peripheral LPS can act in the brain to induce STAT3 activation. Glucocorticoids are known to play a physiological role in the feedback inhibition of immune/inflammatory responses in the endocrine system. Interestingly, we observed no effect of dexamethasone on LPS-induced STAT3 phosphorylation in the hypothalamus. These findings point to the important role of STAT3 in the neuroimmune interaction of inflammation in the brain.

Metabolic and immunological responses associated with in vivo glucocorticoid depletion by adrenalectomy in mature Swiss albino rats

The study is undertaken to determine the effect of adrenal corticosteroid depletion after adrenalectomy on carbohydrate, protein and fat metabolism as well as maturation and functional efficacy of the immunocompetent cells. Beside biochemical and hematological parameters, whether in vivo glucocorticoid depletion has any modulatory effects on splenic macrophage responses to bacterial challenge with regards to intracellular killing, nitric oxide release and cellular integrity, were determined. Major findings of our study indicate that blood glucose, urea and total inorganic phosphate levels showed a time dependent increase in adrenalectomized rats compared to control. Total glycogen content in liver was decreased gradually due to adrenal corticosteroid insufficiency. Hematological parameters like hemoglobin concentration, hematocrit value, total leukocyte count and differential count were also found to increase in the adrenalectomized group with respect to intact group. From the functional study of immunocompetent cells, intracellular killing capacity of splenic macrophages recovered from control and adrenalectomized rats after 10 and 20 days of adrenalectomy showed no significant alteration; however, the function of splenic macrophages recovered from rats after 30 days of adrenalectomy showed altered response. Nitric oxide released from splenic macrophages of adrenalectomized rats was less than that of control animal even after stimulation with lipopolysaccharide. DNA fragmentation assay showed a lesser degree of fragmentation of splenic macrophages obtained from adrenalectomized rats indicating, apoptotic death of cells in this group decreases. Adrenal corticosteroid insufficiency due to adrenalectomy interferes with metabolic and hematopoietic functions and modulates the development and maintenance of normal immunitary status, which in turn influences the inflammatory response.

Steroid hormone synthesis by vaccinia virus suppresses the inflammatory response to infection

The 3beta-hydroxysteroid dehydrogenase (3beta-HSD) isoenzymes play a key role in cellular steroid hormone synthesis. Vaccinia virus (VV) also synthesizes steroid hormones with a 3beta-HSD enzyme (v3beta-HSD) encoded by gene A44L. Here we examined the effects of v3beta-HSD in VV disease using wild-type (vA44L), deletion (vDeltaA44L), and revertant (vA44L-rev) viruses in a murine intranasal model. Loss of A44L was associated with an attenuated phenotype. Early (days 1-3) after infection with vDeltaA44L or control viruses the only difference observed between groups was the reduced corticosterone level in lungs and plasma of vDeltaA44L-infected animals. Other parameters examined (body weight, signs of illness, temperature, virus titres, the pulmonary inflammatory infiltrate, and interferon [IFN]-gamma levels) were indistinguishable between groups. Subsequently, vDeltaA44L-infected animals had reduced weight loss and signs of illness, and displayed a vigorous pulmonary inflammatory response. This was characterized by rapid recruitment of CD4+ and CD8+ lymphocytes, enhanced IFN-gamma production and augmented cytotoxic T lymphocyte activity. These data suggest that steroid production by v3beta-HSD contributes to virus virulence by inhibiting an effective inflammatory response to infection.

Inhibition of leptin-induced IL-1beta expression by glucocorticoids in the brain

Leptin is an important circulating signal for the regulation of food intake and body weight. Glucocorticoids were suggested to play a physiological role in the feedback inhibition of immune/inflammatory responses. In the present study, we examined whether these neuroendocrine effects of glucocorticoids are linked to changes in the leptin-induced expression of IL-1beta and STAT3 activation in the brain. Intravenous injection of leptin induced IL-1beta expression in the hypothalamus. Pretreatment with dexamethasone dose dependently inhibited leptin-induced IL-1beta expression in the hypothalamus. Moreover, dexamethasone inhibited leptin-induced IL-1beta expression in the primary cultured glial cells. In contrast, pretreatment with dexamethasone did not inhibit leptin-induced STAT3 phosphorylation in the hypothalamus. These effects of dexamethasone may not be due to the change in the expression level of the leptin receptor Ob-Ra and Ob-Rb isoforms. Therefore, it is suggested that glucocorticoid negatively regulates leptin-induced IL-1beta expression in the brain.

Stress-dose corticosteroid therapy for sepsis and acute lung injury or acute respiratory distress syndrome in critically ill adults

Sepsis and acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) are associated with high mortality rates despite recent therapeutic advances. Both disease states involve uncontrolled host defense responses that lead to inflammation, endothelial damage, enhanced coagulation, diminished fibrinolysis and fibroproliferation to produce microthrombi, and relative adrenal insufficiency. Corticosteroids inhibit the host defense response and may offer an inexpensive therapeutic option. Results of several randomized, double-blind studies demonstrated no survival benefit and higher secondary infection rates when supraphysiologic doses of corticosteroids were administered for less than 24 hours. Recently, the emphasis of research for corticosteroid therapy has involved adrenocortical replacement dosage regimens administered for several days to weeks, with doses corresponding to the stress level of the disease. Stress-dose therapy with hydrocortisone in patients with septic shock who require vasopressor support, especially if adrenal insufficiency is present, accelerates hemodynamic stability and reduces mortality. The frequency of gastrointestinal hemorrhage was higher with corticosteroid therapy than with placebo, but the occurrence of secondary infections was similar to that of placebo. The only randomized, double-blind study that evaluated stress-dose methylprednisolone therapy for ARDS was terminated early after only 24 patients were enrolled because therapy with methylprednisolone was associated with enhanced survival despite higher secondary infection rates. A multicenter study investigating stress-dose methylprednisolone for ARDS is under way and should provide valuable information. Sufficient data support stress-dose hydrocortisone therapy for vasopressor-dependent septic shock. Stress-dose methylprednisolone therapy for ALI-ARDS requires further study but may be warranted in cases of refractory infection-induced ARDS when impending mortality is likely.

Influence of opioid peptides on human neutrophil apoptosis and activation in vitro

BACKGROUND

It has been shown that cells of the immune system release opioid peptides and possess receptors for them. The concentrations of opioid peptides in the peripheral circulation rapidly increase during inflammation and acute stress response.

AIMS

The effect of opioid peptides Met-enkephalin (M-ENK) and beta-endorphin (beta-END) on the oxidative metabolism of normal human neutrophils and their death by apoptosis in vitro was investigated.

METHODS

Isolated from peripheral blood, neutrophils were incubated in the presence or absence of 10(-6) to 10(-10) M of M-ENK and beta-END for 12 and 18 h. Apoptosis of neutrophils was determined in vitro by flow cytometric analysis of cellular DNA content and Annexin V-FITC protein binding to the cell surface. The MTT-reduction assay was employed to estimate the oxidative metabolism of neutrophils.

RESULTS

Treatment with M-ENK caused a significant increase in apoptotic cells after 18 h of culture: *0 M (control) versus 10(-10) M, p < or = 0.02; **10(-10) M versus 10(-10) M, p < or = 0.02. Treatment with beta-END caused a significant increase in apoptotic cells after 12 h of culture: 0 M versus 10(-8) M, p < or = 0.03; **0 M versus 10(-10) M, p < or = 0.04. We found the significant increase in MTT reduction by neutrophils in the presence of M-ENK and beta-END both before and after the culture. However, the ability of neutrophils to reduce the MTT salt to formazan decreased significantly after the culture.

CONCLUSIONS

We observed that the in vitro effect of opioid peptides on the neutrophil survival and their functional state was time and dose dependent. The presence of antioxidants in the culture medium modifies neutrophil survival.

Effects of malnutrition on the expression of daintain/AIF-1 in the gut mucosa of pigs

The allograft inflammatory factor (AIF-1/daintain) is a hormone-like peptide produced by activated monocytic cells in a variety of traumatic, inflammatory and degenerative lesions. Gut-derived AIF-1 has been shown to modulate insulin production and to attenuate autoimmune diabetes. As the localization of this gastrointestinal peptide in the porcine duodenum is not known and the pig is a convenient model for the study of nutritional modulation of the mucosal immune compartment, we have localized expression of AIF-1 by immunohistology in the duodenum of either malnourished (energy and protein supply 50% of demands, n = 5) or optimally fed pigs (n = 5). AIF-1 macrophages were predominantly located at the villus tip. The number of positively stained cells per high-power field was significantly (P < or = 0.001) higher in the malnourished pigs (74.6 +/- 2.44; least square means +/- SEM) compared to optimally fed pigs (32.56 +/- 1.99). It is likely that the effect in malnourished pigs can be explained by a more pronounced antigen contact of macrophages due to loss of epithelial integrity. Thus, AIF-1 is a novel marker for the study of the nutritional regulation of the mucosal immune system of the pig. AIF-1 expression in the duodenum was further validated by polymerase chain reaction and sequencing. Surprisingly, we detected a slight deviation from the original sequence (probably representing an allelic variation) and an AIF-1 splice variant, previously not known to occur in pigs.

Hypothalamic-pituitary-adrenal axis function and cytokine production in multiple sclerosis with or without interferon-beta treatment

OBJECTIVES

Pro-inflammatory cytokines mediate brain damage in multiple sclerosis (MS); they can also influence the hypothalamic-pituitary-adrenal (HPA) axis function. We evaluated the possible abnormalities of HPA axis function in relapsing-remitting MS (RR-MS).

MATERIAL AND METHODS

IFN-gamma, TNF-alpha and IL-6 production by ex-vivo lymphocytes from 10 normal volunteers and 10 RR-MS patients before and during IFN-beta therapy was assessed; pituitary-adrenal function was evaluated by means of CRH and ACTH stimulation tests.

RESULTS

In untreated patients the production of IFN-gamma, TNF-alpha, IL-6 was increased, and was significantly decreased by IFN-beta. Neither basal, nor stimulated ACTH, cortisol, DHEA, DHEAs, 17-alpha-OH-progesterone levels differed between controls and RR-MS patients, both before and during treatment. Moreover, no correlation was found between endocrine and immune parameters.

CONCLUSION

In MS the HPA axis function seems normal and not influenced by IFN-beta treatment. This result is discussed in relation to the increased production of pro-inflammatory cytokines found in this disease.

Alterations in fuel metabolism in critical illness: hyperglycaemia

Hyperglycaemia is common during critical illness and may be viewed teleologically as a means of ensuring an adequate supply of glucose for the brain and phagocytic cells. Under normal conditions, euglycaemia is maintained by neural, hormonal and hepatic autoregulatory mechanisms. Critical illness promotes hyperglycaemia through an activation of the hypothalamic-pituitary-adrenal axis, which in turn increases hepatic glucose production and inhibits insulin-mediated glucose uptake to skeletal muscle. Sustained hyperglycaemia is associated with adverse consequences that demand its control. Appropriate management includes discontinuing causative drugs, correcting hypokalaemia, treating infection and administering insulin. Insulin therapy also appears to be useful for promoting an anabolic response in skeletal muscle.

Reduced adrenal response to bacterial lipopolysaccharide in interleukin-6-deficient mice

Administration of bacterial lipopolysaccharide (LPS) in rodents induces the release of pro-inflammatory cytokines [tumor necrosis factor (TNF), interleukin (IL)-1, IL-6] and of ACTH and corticosterone. IL-6 is probably an important cytokine in the interaction between the immune system and the hypothalamus-pituitary-adrenal (HPA) axis, but so far the role of IL-6 in lipopolysaccharide (LPS)-induced HPA activation has not been established unequivocally. We examined the effects of intraperitoneal administration of LPS (range 0.25-2000 pg/mouse) on plasma corticosterone, TNFalpha and IL-1alpha levels in IL-6-deficient (IL-6 -/-) and wildtype control (IL-6 +/+) mice. Plasma corticosterone levels increased within one hour in both mouse strains. The corticosterone response was significantly reduced in IL-6 -/- mice, but no differences in TNFalpha or in IL-1alpha plasma levels were found between the two strains. Next, we studied the involvement of IL-1alpha or TNFalpha in the responses to LPS in IL-6 -/- and IL-6 +/+ mice by infusion of recombinant human IL-1 receptor antagonist (IL-1ra), or by injection of anti-TNFalpha antibodies. Pretreatment with IL-1ra or with anti-TNFalpha did not affect the corticosterone response to LPS, neither in IL-6 -/-, nor in IL-6 +/+ mice. Our data suggest that in the stimulation of the HPA axis by LPS in mice blockade of either IL-1alpha or TNFalpha may be compensated for by other mediators. The reduced adrenal response after LPS administration found in IL-6 -/- mice indicates a distinct role for IL-6 in the activation of the HPA axis by LPS.

The hypothalamic-pituitary-adrenal axis of patients with severe sepsis: altered response to corticotropin-releasing hormone

OBJECTIVE

To investigate the functional integrity of the hypothalamic-pituitary-adrenal (HPA) axis in patients with severe sepsis by stimulating with corticotropin-releasing hormone (CRH).

DESIGN

Prospective observational study in consecutive intensive care unit patients with severe sepsis.

SETTING

Surgical intensive care unit and outpatient department of endocrinology in a university hospital.

PATIENTS

The study included 20 patients with the diagnosis of severe sepsis; six critically ill, nonseptic patients after major surgery; ten patients with primary adrenal insufficiency; ten patients with anterior pituitary insufficiency; and ten individuals without clinical signs of HPA axis disturbance.

INTERVENTIONS

CRH tests were performed with an intravenous bolus injection of 100 microg of human CRH.

MEASUREMENTS AND MAIN RESULTS

We studied the functional integrity of the HPA axis in patients with severe sepsis by performing the CRH test. In addition, during the period of severe sepsis, we repeatedly measured basal plasma concentrations of adrenocorticotropin hormone (ACTH) and cortisol. The mean basal plasma cortisol concentration was decreased significantly in nonsurvivors with severe sepsis (288.8 +/- 29.1 [sem] nmol/L) compared with survivors (468.1+/- 18.6 nmol/L; p <.01). By calculating the ACTH/cortisol indices, we found no evidence for adrenal insufficiency in patients with severe sepsis. The mean ACTH/cortisol indices of nonsurvivors with severe sepsis (0.02 +/- 0.008) and survivors (0.01 +/- 0.002) were significantly lower compared with the index of patients with primary adrenal insufficiency (6.8 +/- 1.0; p <.001). In contrast, in nonsurvivors with severe sepsis, the plasma cortisol response to CRH stimulation was impaired compared with survivors: The mean basal cortisol concentration within the CRH test was 269.4 +/- 39.8 nmol/L in nonsurvivors compared with 470.8 +/- 48.4 nmol/L in survivors and increased to a peak value of 421.6 +/- 72.6 nmol/L in nonsurvivors and 680.7 +/- 43.8 nmol/L in survivors (p <.02). However, the change in plasma cortisol, expressed as mean +/- sem and calculated by subtracting the basal cortisol from the peak cortisol after CRH stimulation, was not significantly different in survivors with severe sepsis (243.5 +/- 36.1, range 111.0-524.0 nmol/L, n = 15) compared with nonsurvivors (161.0 +/- 38.9, range 42.0-245.0 nmol/L, n = 5; p >.05).

CONCLUSIONS

We found lower basal plasma cortisol concentrations in nonsurvivors compared with survivors of severe sepsis. In addition, the plasma cortisol response to a single CRH stimulation was impaired in nonsurvivors compared with survivors. Reduced responses to CRH stimulation may reflect a state of endocrinologic organ dysfunction in severe sepsis.

The role of interleukin-6 in the human adrenal gland

Interleukin (IL)-6 is a potent activator of the hypothalamic-pituitary-adrenal (HPA) axis on all levels in humans, and appears to play a pathogenic role in conditions related to chronic stress and physiological ageing; with physiological ageing showing a similar hormonal and immunological pattern to chronic stress. IL-6 and its receptor IL-6R are co-expressed at similar sites in the human adrenal gland, which seems to be an important source of IL-6 production. In vitro, in primary cultures of adrenal gland cells, chronic exposure to IL-6 stimulates adrenocortical steroid release in a time- and dose-dependent manner. This explains the high systemic cortisol levels in the absence of adequate plasma concentrations of corticotropin (ACTH) observed in patients after long-term treatment with IL-6. It could therefore be concluded that in situations of prolonged stress, when corticotropin-releasing hormone and ACTH release are suppressed by feedback inhibition due to circulating glucocorticoids, IL-6 maintains the elevated glucocorticoid levels by direct stimulation of adrenocortical steroidogenesis via autocrine/paracrine mechanisms.

Evidence for a positive correlation between serum cortisol levels and IL-1beta production by peripheral mononuclear cells in anorexia nervosa

A hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis has been reported in anorexia nervosa (AN), together with some immunological abnormalities, involving citokine - and particularly Tumor Necrosis-Factor-alpha (TNF-alpha) - production by polymorphonuclear cells. The ability of pro-inflammatory cytokines to activate the HPA axis is well known; however, there are no data demonstrating an interdependence between immunological and endocrine response in AN. To investigate the presence of a correlation between immune response and pituitary-adrenal function, plasma ACTH and serum cortisol concentrations were measured in 13 AN patients and in the same number of controls. TNF-alpha and interleukin (IL)-1beta production by ex-vivo unstimulated and LPS-stimulated peripheral mononuclear cells was also assessed. Circulating cortisol concentrations were higher (p<0.01) in AN (156.7 +/- 45.1 microg/l, mean +/- SD) than in controls (105.9 +/- 25.7 microg/l). Unstimulated IL-1beta release in supernatants of mononuclear cell cultures was slightly but not significantly higher in AN than in controls, while TNF-alpha release was similar in the two groups. A positive correlation was found between IL-1beta concentrations in unstimulated culture supranatants and serum cortisol levels in AN (r=0.782, p=0.002), while in normal subjects there was a trend toward a negative correlation; a slight positive correlation, while not significant, between IL-1beta and plasma ACTH, as well as between TNF-alpha and serum cortisol was also found in AN. These data suggest that the normal relationship between pro-inflammatory cytokines release, particularly IL-1beta, and cortisol secretion is deranged in AN.

Interleukin-3 and interleukin-6 stimulate bovine adrenal cortisol secretion through different pathways

Several interleukins have been reported to play a major role in the regulation of steroid secretion at all three levels of the hypothalamic-pituitary-adrenal axis. The objective of this study was to investigate the effect of interleukin-3 (IL-3) and interleukin-6 (IL-6) on cortisol secretion of bovine adrenocortical cells in primary culture under serum-free conditions. Both IL-3 and IL-6 stimulated basal cortisol secretion dose-dependently to a similar extent at a similar time course. After incubation with IL-3 or IL-6 at concentrations of 100 microg/l, a maximum 4.1-fold increase of the cortisol secretion was reached after 12 h (P<0.01). Coincubation of IL-3 and IL-6 (100 microg/l) revealed no significant synergism. To elucidate a possible involvement of arachidonic acid metabolites in the signal transduction, we coincubated IL-3 or IL-6 together with the cyclo-oxygenase inhibitor indometacin or the lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA). Coincubation with indometacin completely abolished the stimulatory effect of IL-6 but had no effect on IL-3 stimulated cortisol secretion. In contrast, specific inhibition of the lipoxygenase system by nordihydroguaiaretic acid blocked IL-3 stimulated steroidogenesis while the effect of IL-6 was not affected. Neither IL-3 nor IL-6 altered cAMP levels significantly, whereas ACTH significantly induced cAMP levels in parallel to its steroidogenic effect. In conclusion, our data indicate that IL-3 and IL-6 stimulate the steroid secretion of bovine adrenocortical cells to a similar extent and with a similar time course. However, the effects of IL-3 and IL-6 are mediated through different, cAMP-independent pathways. While the stimulatory effect of IL-3 seems to be dependent on the lipoxygenase pathway, the effect of IL-6 on adrenocortical cortisol secretion is mediated through the cyclo-oxygenase pathway.

Influence of granulocyte-macrophage colony stimulating factor on pituitary-adrenal axis (PAA) in rats in vivo

We have studied the in vivo influence of granulocyte-macrophage colony stimulating factor (GM-CSF) on blood plasma concentration of adrenocorticotropic hormone (ACTH) and corticosterone in Wistar rats. The administration of 10 micrograms/kg b.w. GM-CSF at 45 (P < 0.01), 90 (P < 0.01) and at 45 (P < 0.001), 90 (P < 0.001) and 180 min (P < 0.001) increased the secretion of ACTH and corticosterone, respectively. Prolonged administration of 10 micrograms/kg b.w. of GM-CSF increased the ACTH (P < 0.001) and corticosterone (P < 0.001) concentration in blood plasma. We have also found that chronic treatment with 10 micrograms/kg b.w. of GM-CSF increased the proliferative activity of corticotrophs (P < 0.05), but it did not significantly change the total cell proliferation in the anterior pituitary gland. Moreover, this cytokine increased cell proliferation of the adrenal cortex (P < 0.001). These experiments suggest that GM-CSF activates the pituitary-adrenal axis and support the hypothesis of bidirectional associations between the immune and neuroendocrine systems.

Insulin-like growth factor-1 (IGF-1) and growth hormone (GH) in immunity and inflammation

In recent years many efforts have been undertaken to elucidate the complex interactions between mediators of the endocrine system and the immune system. The main effector of growth hormone (GH) is insulin-like growth factor-1 (IGF-1), an endocrine mediator of growth and development under physiological conditions. Besides this important function, IGF-1 also plays a prominent role in the regulation of immunity and inflammation. This article will address the involvement of IGF-1 in innate as well as acquired immunity and host-defense. We also discuss the role of IGF-1 in the course of inflammatory disorders, including sepsis and sepsis-induced catabolism as well as degenerative arthritis. Based on recent insights, we finally examine the pathophysiological background, potential pitfalls and perspectives of IGF-1 suppletion therapy in these conditions.

Pain in fibromyalgia

Just as our caveman forebears were frail in the face of predatory animals, we are frail in today's society of childhood neglect or abuse, bumper-to-bumper traffic, frustration at work, and multiple daily hassles. The same neuroendocrine systems and pain regulatory mechanisms that protected early man during acute stress are still encoded in our genome, but may be maladaptive in psychologically and physiologically vulnerable people faced with chronic stress. Many patients with fibromyalgia become vulnerable because of the long-lasting psychological and neurophysiological effects of negative experiences in childhood. Ill-equipped with positive cognitive, emotional, and behavioral skills as adults, they display maladaptive coping strategies, low self-efficacy, and negative mood when confronted with the inevitable stressors of life. Psychological distress ensues, which reduces thresholds for pain perception and tolerance (already relatively low in women) even further. Converging lines of psychological and neurobiological evidence strongly suggest that chronic stress-related blunting of the HPA, sympathetic, and other axes of the stress response together with associated alterations in pain regulatory mechanisms may finally explain the pain and fatigue of fibromyalgia. Vulnerable people who can be classified by the ACR criteria as having fibromyalgia do not have a discrete disease. They are simply the most ill in a continuum of distress, chronic pain, and painful tender points in the general population.

Interferon-gamma has immunomodulatory effects with minor endocrine and metabolic effects in humans

To evaluate whether interferon-gamma (IFN-gamma) is involved in the interaction between the immune and endocrine systems in vivo, we studied six healthy subjects twice in a placebo-controlled trial: once after administration of recombinant human IFN-gamma and, on another occasion, after administration of saline. The rate of appearance of glucose was determined by infusion of [6,6-2H2]glucose and resting energy expenditure by indirect calorimetry. Human leukocyte antigen-DR gene expression on monocytes and serum neopterin increased after administration of IFN-gamma (P < 0.05 vs. control). IFN-gamma increased serum interleukin-6 levels significantly. Levels of tumor necrosis factor-alpha remained below detection limits. IFN-gamma increased plasma concentrations of ACTH and cortisol (P < 0.05 vs. control), IFN-gamma did not alter concentrations of growth hormone, (nor)epinephrine, insulin, C peptide, glucagon, or insulin-like growth factor I. IFN-gamma did not alter plasma concentrations of glucose and free fatty acids nor the rate of appearance of glucose. IFN-gamma increased resting energy expenditure significantly. We conclude that IFN-gamma is a minor stimulator of the endocrine and metabolic pathways. Therefore, IFN-gamma by itself is probably not a major mediator in the interaction between the immune and the endocrine and metabolic systems.

Endogenous glucocorticoids released during acute toxic liver injury enhance hepatic IL-10 synthesis and release

Endogenous glucocorticoids are known to play a role in the regulation of the inflammatory response possibly by modulating pro- and anti-inflammatory cytokine expression. We examined endogenous glucocorticoid secretion, hepatic damage, tumor necrosis factor-alpha (TNF-alpha), and interleukin-10 (IL-10) mRNA expression and release in rats treated with carbon tetrachloride (CCl4) after treatment with vehicle or a glucocorticoid receptor antagonist (RU-486). Rats treated with CCl4 demonstrated striking elevations of plasma corticosterone levels. Inhibition of endogenous glucocorticoid activity by pretreatment with the glucocorticoid receptor antagonist RU-486 resulted in augmented CCl4-mediated hepatotoxicity, as reflected by histology and serum transaminase levels, which were independent of alterations in serum TNF-alpha levels or hepatic mRNA expression. CCl4 treatment resulted in enhanced hepatic IL-10 mRNA expression and elevated serum IL-10 levels, which were markedly attenuated by glucocorticoid receptor blockade. In summary, significant endogenous glucocorticoid release occurs during acute toxic liver injury in the rat and suppresses the inflammatory response independent of effects on TNF-alpha but possibly by upregulating hepatic IL-10 production.

Immune-endocrine interactions in the mammalian adrenal gland: facts and hypotheses

Several cytokines, which are the major mediators of the inflammatory responses, are well-known to stimulate the hypothalamopituitary corticotropin-releasing hormone (CRH)/adrenocorticotropic hormone (ACTH) system, thereby evoking secretory responses by the adrenal cortex. Many of these cytokines, including interleukin-1 (IL-1), IL-2, IL-6, tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (INF-gamma) are synthesized in the adrenal gland by both parenchymal cells and resident macrophages, and the release of some of them (e.g., IL-6 and TNF-alpha) is regulated by the main agonists of steroid hormone secretion (e.g., ACTH and angiotensin-II) and bacterial endotoxins. Adrenocortical and adrenomedullary cells are provided with specific receptors for IL-1, IL-2, and IL-6. IL-1 and TNF-alpha directly inhibit aldosterone secretion of zona glomerulosa cells, whereas IL-6 enhances it. IL-2, IL-3, IL-6, and INF-alpha are able to directly stimulate glucocorticoid production by zona fasciculata and zona reticularis cells, whereas IL-1 exerts an analogous effect through an indirect mechanism involving the stimulation of catecholamine release by chromaffin cells and/or the activation of the intramedullary CRH/ACTH system; again, TNF-alpha depresses glucocorticoid synthesis. IL-6 raises androgen secretion by inner adrenocortical layers. IL-1 enhances the proliferation of adrenocortical cells, and findings suggest that cytokines may control the apoptotic deletion of senescent zona reticularis cells. The relevance of the intraadrenal cytokine system in the fine-tuning of the secretion and growth of the adrenal cortex under normal conditions remains to be explored. However, indirect proof is available that local immune-endocrine interactions may play an important role in modulating adrenal responses to inflammatory and immune challenges and stresses.

Endotoxin injection increases growth hormone and somatostatin secretion in sheep

Endotoxin has been shown to stimulate GH secretion in human and sheep. However, changes in hypothalamic neurohormones involved in the GH regulation by endotoxin have never been studied in vivo. In sheep it is possible to collect hypophysial portal blood (HPB) and quantify GH-releasing hormone (GHRH) and somatostatin (SRIH) secretion under physiological conditions. The purpose of this study was to determine the effect of an acute i.v. endotoxin administration on the secretion of these peptides in sheep. Endotoxin induced a sustained increase of GH (x6.2 +/- 1.3) in intact rams. This stimulation was delayed and less marked when compared with the hypothalamic-pituitary-adrenal axis. Surprisingly, the GH increase was associated with an important rise of jugular (x10.6 +/- 2.4) and portal (x7.9 +/- 3) SRIH levels, without a significant GHRH increase. To determine if the portal SRIH increase was a consequence of an increased short feedback of GH, we studied GH response to endotoxin after a previous GHRH injection to deplete the pituitary pools of GH. In that case, despite the absence of increase of GH after endotoxin treatment, SRIH levels was markedly increased. For the first time we have observed an experimental situation in sheep with a simultaneous and closed amplitude increase in jugular and portal SRIH. The source of jugular SRIH is likely the gastrointestinal tract and the increased jugular SRIH release in systemic circulation might be in part responsible for the increase of hypophysial portal SRIH. Ultimately our results show that endotoxin induced a complex reaction at multiple levels with a specific increase in both portal and peripheral SRIH levels. The surprising association of a lack of change in GHRH release and an increased secretion of SRIH with the increase of GH suggests that the effect of endotoxin on GH axis is mainly a pituitary one. The selective blockade of somatostatin should be useful for a better knowledge of the role of SRIH stimulation in the physiopathology of septic shock.

Interleukin-6 and the interleukin-6 receptor in the human adrenal gland: expression and effects on steroidogenesis

Interleukin (IL)-6 is a potent activator of the human hypothalamicpituitary-adrenal axis. After chronic administration of IL-6 in humans, there is a substantial elevation of cortisol, whereas ACTH levels are blunted. Thus, we investigated whether IL-6 and/or the IL-6 receptor (IL-6R) are expressed in the human adrenal gland and whether IL-6 could cause the release of steroid hormones by a direct action on adrenal cells in primary culture. The expression of IL-6 and IL-6R was investigated with RT-PCR and immunohistochemistry, and the effects on human adrenal steroidogenesis were tested with IL-6 in vitro. To avoid effects mediated by macrophages, we depleted adrenal primary cultures from macrophages using specific mouse antihuman CD68 and sheep antimouse IgG conjugated magnetic beads. The results showed that 1): IL-6 and IL-6R are expressed in adrenal cell cultures, including all cell types and those depleted of macrophages; 2) IL-6R is mainly expressed in the zona reticularis and the inner zona fasciculata; positive signals from the zona glomerulosa and the medulla occurred in single cells; and 3) IL-6 regulates adrenal synthesis of mineralocorticoids, glucocorticoids, and androgens in vitro, dependent on time and dose, in the absence of macrophages. After 24 h, aldosterone secretion increased to 172 +/- 28% SEM, cortisol to 177 +/- 27% SEM, and dehydroepiandrosterone to 153 +/- 20% SEM of basal secretion. These findings, in combination with previous investigations, suggest that IL-6 exerts its acute action via the hypothalamus and the pituitary. In the adrenal gland, however, IL-6 seems to be a long-term regulator of stress response, integrating the responses of all cortical zones to stimuli from the immune and endocrine system.

Characterization of early cytokine responses and an interleukin (IL)-6-dependent pathway of endogenous glucocorticoid induction during murine cytomegalovirus infection

Early infection with murine cytomegalovirus (MCMV) induces circulating levels of interleukin (IL)-12, interferon (IFN)-gamma, and tumor necrosis factor (TNF). Studies presented here further characterize these responses by defining kinetics and extending evaluation to include IL-1, IL-6, and glucocorticoids. IL-12 p40, IFN-gamma, TNF, IL-1alpha, and IL-6 were shown to be increased, but IL-1beta was undetectable, in serum of MCMV-infected mice. The IL-12 p40, IFN-gamma, TNF, and IL-6 responses were dramatic with peak levels reaching >150-10,000 pg/ml at 32-40 h after infection and rapidly declining thereafter. Glucocorticoid induction, peaking at 36 h and reaching 30-fold increases above control values, accompanied the cytokine responses. Mice with cytokine deficiencies or neutralized cytokine function demonstrated that IL-6 was the pivotal mediator of the glucocorticoid response, with IL-1 contributing to IL-6 production. The IL-6 requirement appeared to be specific for virus-type stimuli as the synthetic analogue of viral nucleic acid, polyinosinic-polycytidylic acid, also induced IL-6-dependent glucocorticoid release, but treatments with the bacterial product lipopolysaccharide and a non-immune physical restraint stressor elicited IL-6-independent responses. Collectively, the results identify IL-6 as a primary mediator of glucocorticoid induction, and elucidate specific pathways of interactions between immune and neuroendocrine systems during viral infection.

Direct effects of interleukin-6 on human adrenal cells

Interleukin-6 (IL-6), which is expressed in the human adrenal gland, was found to be a very potent activator of the human HPA axis. So far nothing is known about a local paracrine or autocrine influence of IL-6 within the human adrenal. In this study, the expression of IL-6 and the IL-6 receptor by human adrenal cells in vitro could be demonstrated by immunohistochemistry. Possible effects of IL-6 on steroid release were tested by incubating human adrenal cells in vitro with IL-6 [10(-8) M]. Adrenal steroids were stimulated by IL-6: aldosterone 184 +/- 23, cortisol 198 +/- 19, DHEA 140 +/- 8 and androstenedione 136 +/- 5 (results are means +/- s.e.m. in %). In conclusion, IL-6 can act directly on human adrenal cells and appears to be an important paracrine or autocrine factor.

Effect of beta-endorphin on adherence, chemotaxis and phagocytosis of Candida Albicans by peritoneal macrophages

There is growing evidence about the role of neuroendocrine hormones in the regulation of the immune system. In the present study we have examined effects on different stages of phagocytic function of peritoneal macrophages from BALB/c mice induced by beta-endorphin. Peritoneal macrophages were incubated (30 min at 37 degrees C) in vitro with 0.22, 0.5 or 2200 ng/ml of this hormone. Adherence capacity was evaluated by means of a substrate adherence technique, chemotaxis in Boyden chambers, and ingestion of Candida albicans on migration inhibitory factor (MIF) dishes. No changes in adherence capacity were found. Chemotaxis, however, increased, and concentration of beta-endorphin correlated directly with stimulation. Incubation of macrophages with 0.5 ng/ml of beta-endorphin also stimulated phagocytosis of Candida albicans. These results indicate that beta-endorphin acts on peritoneal marine macrophages, stimulating some stages of their phagocytic function.