The interleukin-1 type I receptor is expressed in human hypothalamus

Neuroinflammation in Post-Traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) is a well-known mental illness, which is caused by various stressors, including memories of past physical assaults and psychological pressure. It is diagnosed as a mental and behavioral disorder, but increasing evidence is linking it to the immune system and inflammatory response. Studies on the relationship between inflammation and PTSD revealed that patients with PTSD had increased levels of inflammatory cytokine biomarkers, such as interleukin-1, interleukin-6, tumor necrosis factor-α, nuclear factor-κB, and C-reactive protein, compared with healthy controls. In addition, animal model experiments imitating PTSD patients suggested the role of inflammation in the pathogenesis and pathophysiology of PTSD. In this review, we summarize the definition of PTSD and its association with increased inflammation, its mechanisms, and future predictable diseases and treatment possibilities. We also discuss anti-inflammatory treatments to address inflammation in PTSD.

Low glucocorticoids in stress-related disorders: the role of inflammation

There is evidence that plasma cortisol concentration can be either increased or decreased in patients with depression and related anxiety and stress-related disorders; the exact pathophysiological mechanisms of this state are not almost clear. Several distinct theories were proposed and mechanisms, which could lead to decreased glucocorticoid signaling and/or levels, were described. However, there is a possible drawback in almost all the theories proposed: insufficient attention to the inflammatory process, which is undoubtedly present in several stress-related disorders, including post-traumatic stress disorder (PTSD). Previous studies only briefly mentioned the presence of an inflammatory reaction's signs in PTSD, without giving it due importance, although recognizing that it can affect the course of the disease. With that, the state of biochemical changes, characterized by the low glucocorticoids, glucocorticoid receptor's resistance and the signs of the persistent inflammation (with the high levels of circulating cytokines) might be observed not only in PTSD but in coronary heart diseases and systemic chronic inflammatory diseases (rheumatoid arthritis) as well. That is why the present review aims to depict the pathophysiological mechanisms, which lead to a decrease in glucocorticoids in PTSD due to the action of inflammatory stimuli. We described changes in the glucocorticoid system and inflammatory reaction as parts of an integral system, where glucocorticoids and the glucocorticoid receptor reside at the apex of a regulatory network that blocks several inflammatory pathways, while decreased glucocorticoid signaling and/or level leads to unchecked inflammatory reactions to promote pathologies such as PTSD. LAY SUMMARY This review emphasizes the importance of inflammatory reaction in the development of puzzling conditions sometimes observed in severe diseases including post-traumatic stress disorder - the decreased levels of glucocorticoids in the blood. Following the classical concepts, one would expect an increase in glucocorticoid hormones, since they are part of the feedback mechanism in the immune system, which reduces stress and inflammation. However, low levels of glucocorticoid hormones are also observed. Thus, this review describes potential mechanisms, which can lead to the development of such a state.

A Multiplex Protein Panel Applied to Cerebrospinal Fluid Reveals Three New Biomarker Candidates in ALS but None in Neuropathic Pain Patients

The objective of this study was to develop and apply a novel multiplex panel of solid-phase proximity ligation assays (SP-PLA) requiring only 20 μL of samples, as a tool for discovering protein biomarkers for neurological disease and treatment thereof in cerebrospinal fluid (CSF). We applied the SP-PLA to samples from two sets of patients with poorly understood nervous system pathologies amyotrophic lateral sclerosis (ALS) and neuropathic pain, where patients were treated with spinal cord stimulation (SCS). Forty-seven inflammatory and neurotrophic proteins were measured in samples from 20 ALS patients and 15 neuropathic pain patients, and compared to normal concentrations in CSF from control individuals. Nineteen of the 47 proteins were detectable in more than 95% of the 72 controls. None of the 21 proteins detectable in CSF from neuropathic pain patients were significantly altered by SCS. The levels of the three proteins, follistatin, interleukin-1 alpha, and kallikrein-5 were all significantly reduced in the ALS group compared to age-matched controls. These results demonstrate the utility of purpose designed multiplex SP-PLA panels in CSF biomarker research for understanding neuropathological and neurotherapeutic mechanisms. The protein changes found in the CSF of ALS patients may be of diagnostic interest.

Neuroimmune regulation of homeostatic synaptic plasticity

Homeostatic synaptic plasticity refers to a set of negative-feedback mechanisms that are used by neurons to maintain activity within a functional range. While it is becoming increasingly clear that homeostatic regulation of synapse function is a key principle in the nervous system, the molecular details of this regulation are only beginning to be uncovered. Recent evidence implicates molecules classically associated with the peripheral immune system in the modulation of homeostatic synaptic plasticity. In particular, the pro-inflammatory cytokine TNFα, class I major histocompatibility complex, and neuronal pentraxin 2 are essential in the regulation of the compensatory synaptic response that occurs in response to prolonged neuronal inactivity. This review will present and discuss current evidence implicating neuroimmune molecules in the homeostatic regulation of synapse function. This article is part of the Special Issue entitled 'Homeostatic Synaptic Plasticity'.

Detailed analysis of inflammatory and neuromodulatory cytokine secretion from human NT2 astrocytes using multiplex bead array

Astrocytes are a very important cell type in the brain fulfilling roles in both neuroimmunology and neurotransmission. We have conducted the most comprehensive analysis of secreted cytokines conducted to date (astrocytes of any source) to determine whether astrocytes derived from the human Ntera2 (NT2) cell-line are a good model of human primary astrocytes. We have compared the secretion of cytokines from NT2 astrocytes with those produced in astrocyte enriched human brain cultures and additional cytokines implicated in brain injury or known to be expressed in the human brain. The concentration of cytokines was measured in astrocyte conditioned media using multiplex bead array (MBA), where 18 cytokines were measured simultaneously. Resting NT2 astrocytes produced low levels (∼1-30 pg/ml) of MIP1α, IL-6 and GM-CSF and higher levels of MCP-1, IP-10 and IL-8 (1-11 ng/ml) under non-inflammatory conditions. All of these in addition to IL-1β, TNFα, and IL-13, were increased by pro-inflammatory activation (TNFα or IL-1β stimulation). In contrast, IL-2, IL-4, IL-5, IL-7, IL-10, IL-12, LTα, and IFNγ were not detected in astrocyte conditioned media under any of the culture conditions tested. NT2 astrocytes were unresponsive to IL-2 and the adenyl cyclase agonist, forskolin. Interestingly, IFNγ stimulation selectively increased IP-10 secretion only. As astrocytes stimulated with IL-1β or TNFα produced several chemokines in the ng/ml range, we next assessed the chemoattractant properties of these cells. Conditioned media from TNFα-stimulated astrocytes significantly chemoattracted leukocytes from human blood. This study provides the most comprehensive analysis of cytokine production by human astrocytes thus far, and shows that NT2 astrocytes are highly responsive to pro-inflammatory mediators including TNFα and IL-1β, producing cytokines and chemokines capable of attracting leukocytes from human blood. We conclude that in the absence of adult human primary astrocytes that NT2-astrocytes may provide a valuable alternative to study the immunological behaviour of human astrocytes.

Neuromodulatory role of endogenous interleukin-1β in acute seizures: possible contribution of cyclooxygenase-2

The function of endogenous interleukin-1β (IL-1β) signaling in acute seizure activity was examined using transgenic mice harboring targeted deletions in the genes for either IL-1β (Il1b) or its signaling receptor (Il1r1). Acute epileptic seizure activity was modeled using two mechanistically distinct chemoconvulsants, kainic acid (KA) and pentylenetetrazole (PTZ). KA-induced seizure activity was more severe in homozygous null (-/-) Il1b mice compared to their wild-type (+/+) littermate controls, as indicated by an increase in the incidence of sustained generalized convulsive seizure activity. In the PTZ seizure model, the incidence of acute convulsive seizures was increased in both Il1b and Il1r1-/- mice compared to their respective +/+ littermate controls. Interestingly, the selective cyclooxygenase (COX)-2 inhibitor, rofecoxib, mimicked the effect of IL-1β deficiency on PTZ-induced convulsions in Il1r1+/+ but not -/- mice. Together, these results suggest that endogenous IL-1β possesses anticonvulsive properties that may be mediated by arachidonic acid metabolites derived from the catalytic action of COX-2.

Astrocytes support hippocampal-dependent memory and long-term potentiation via interleukin-1 signaling

Recent studies indicate that astrocytes play an integral role in neural and synaptic functioning. To examine the implications of these findings for neurobehavioral plasticity we investigated the involvement of astrocytes in memory and long-term potentiation (LTP), using a mouse model of impaired learning and synaptic plasticity caused by genetic deletion of the interleukin-1 receptor type I (IL-1RI). Neural precursor cells (NPCs), derived from either wild type (WT) or IL-1 receptor knockout (IL-1rKO) neonatal mice, were labeled with bromodeoxyuridine (BrdU) and transplanted into the hippocampus of either IL-1rKO or WT adult host mice. Transplanted NPCs survived and differentiated into astrocytes (expressing GFAP and S100β), but not to neurons or oligodendrocytes. The NPCs-derived astrocytes from WT but not IL-1rKO mice displayed co-localization of GFAP with the IL-1RI. Four to twelve weeks post-transplantation, memory functioning was examined in the fear-conditioning and the water maze paradigms and LTP of perforant path-dentate gyrus synapses was assessed in anesthetized mice. As expected, IL-1rKO mice transplanted with IL-1rKO cells or sham operated displayed severe memory disturbances in both paradigms as well as a marked impairment in LTP. In contrast, IL-1rKO mice transplanted with WT NPCs displayed a complete rescue of the impaired memory functioning as well as partial restoration of LTP. These findings indicate that astrocytes play a critical role in memory functioning and LTP, and specifically implicate astrocytic IL-1 signaling in these processes. The results suggest novel conceptualization and therapeutic targets for neuropsychiatric disorders characterized by impaired astrocytic functioning concomitantly with disturbed memory and synaptic plasticity.

Interleukin-1beta: a bridge between inflammation and excitotoxicity?

Interleukin-1 (IL-1) is a proinflammatory cytokine released by many cell types that acts in both an autocrine and/or paracrine fashion. While IL-1 is best described as an important mediator of the peripheral immune response during infection and inflammation, increasing evidence implicates IL-1 signaling in the pathogenesis of several neurological disorders. The biochemical pathway(s) by which this cytokine contributes to brain injury remain(s) largely unidentified. Herein, we review the evidence that demonstrates the contribution of IL-1beta to the pathogenesis of both acute and chronic neurological disorders. Further, we highlight data that leads us to propose IL-1beta as the missing mechanistic link between a potential beneficial inflammatory response and detrimental glutamate excitotoxicity.

System x(c)- activity and astrocytes are necessary for interleukin-1 beta-mediated hypoxic neuronal injury

The purpose of this study was to elucidate the cellular/biochemical pathway(s) by which interleukin-1beta (IL-1beta) contributes to the pathogenesis of hypoxic-ischemic brain damage. In vivo, IL-1 receptor type I (IL-1RI)-deficient mice showed smaller infarcts and less neurological deficits than wild-type animals after a 90 min reversible middle cerebral artery occlusion. In vitro, IL-1beta mediated an enhancement of hypoxic neuronal injury in murine cortical cultures that was lacking in cultures derived from IL-1RI null mutant animals and was blocked by the IL-1 receptor antagonist or an IL-1RI blocking antibody. This IL-1beta-mediated potentiation of hypoxic neuronal injury was associated with an increase in both cellular cystine uptake ([cystine]i) and extracellular glutamate levels ([glutamate]e) and was prevented by either ionotropic glutamate receptor antagonism or removal of L-cystine, suggesting a role for the cystine/glutamate antiporter (System x(c)-). Indeed, dual System x(c)-/metabotropic glutamate receptor subunit 1 (mGluR1) antagonism but not selective mGluR1 antagonism prevented neuronal injury. Additionally, cultures derived from mGluR1-deficient mice exhibited the same potentiation in injury after treatment with IL-1beta as wild-type cultures, an effect prevented by System x(c)-/mGluR1 antagonism. Finally, assessment of System x(c)- function and kinetics in IL-1beta-treated cultures revealed an increase in velocity of cystine transport (Vmax), in the absence of a change in affinity (Km). Neither the enhancement in [cystine]i, [glutamate]e, or neuronal injury were observed in chimeric cultures consisting of IL-1RI(+/+) neurons plated on top of IL-1RI(-/-) astrocytes, highlighting the importance of astrocyte-mediated alterations in System x(c)- as a novel contributor to the development and progression of hypoxic neuronal injury.

(Peri)vascular production and action of pro-inflammatory cytokines in brain pathology

In response to tissue injury or infection, the peripheral tissue macrophage induces an inflammatory response through the release of IL-1β (interleukin-1β) and TNFα (tumour necrosis factor α). These cytokines stimulate macrophages and endothelial cells to express chemokines and adhesion molecules that attract leucocytes into the peripheral site of injury or infection. The aims of the present review are to (i) discuss the relevance of brain (peri)vascular cells and compartments to bacterial meningitis, HIV-1-associated dementia, multiple sclerosis, ischaemic and traumatic brain injury, and Alzheimer's disease, and (ii) to provide an overview of the production and action of pro-inflammatory cytokines by (peri)vascular cells in these pathologies of the CNS (central nervous system). The brain (peri)vascular compartments are highly relevant to pathologies affecting the CNS, as infections are almost exclusively blood-borne. Insults disrupt blood and energy flow to neurons, and active brain-to-blood transport mechanisms, which are the bottleneck in the clearance of unwanted molecules from the brain. Perivascular macrophages are the most reactive cell type and produce IL-1β and TNFα after infection or injury to the CNS. The main cellular target for IL-1β and TNFα produced in the brain (peri)vascular compartment is the endothelium, where these cytokines induce the expression of adhesion molecules and promote leucocyte infiltration. Whether this and other effects of IL-1 and TNF in the brain (peri)vascular compartments are detrimental or beneficial in neuropathology remains to be shown and requires a clear understanding of the role of these cytokines in both damaging and repair processes in the CNS.

Homeostatic alterations induced by interleukin-1β microinjection into the orbitofrontal cortex in the rat

The present experiments were designed to elucidate the effect of direct orbitofrontal cortical administration of interleukin-1beta (IL-1beta) on the homeostatic regulation. Short- and long-term food intakes (FI), water intakes and body temperature (BT) were measured before and after a bilateral microinjection of IL-1beta (with or without paracetamol /P/ pretreatment) into the orbitofrontal cortex (OBF) of Wistar rats, and the effects were compared with those found in vehicle-treated and i.p. injected IL-1beta, IL-1beta+P or control animals. In addition, blood glucose levels (BGLs), along a glucose tolerance test, and plasma concentrations of insulin, leptin, cholesterol, triglycerides and urate were determined in cytokine treated and control rats. Short-term FI was suppressed after orbitofrontal cortical or peripheral application of IL-1beta. In the long-term FI, however, there was no significant difference among the groups. Cytokine microinjection into the OBF, similar to the i.p. administration, was also followed by a significant increase in BT. Pretreatment with P failed to influence the anorexigenic and hyperthermic effects of the centrally administered IL-1beta. The sugar load led to a diabetes-like prolonged elevation of BGL in the IL-1beta treated animals. Following cytokine administration, plasma levels of insulin and that of triglycerides were found decreased, whereas that of uric acid increased. The present findings confirm that the OBF is one of the neural routes through which IL-1beta exerts modulatory effect on the central homeostatic regulation.

Single neuron activity changes to interleukin-1β in the orbitofrontal cortex of the rat

The orbitofrontal cortex (OBF) is known to play important roles in various regulatory processes. Our preliminary behavioral studies showed homeostatic alterations after orbitofrontal cortical microinjection of interleukin-1beta (IL-1beta) in the rat. To elucidate whether the above alterations were due to direct neuronal action of the cytokine, extracellular single neuron activity was recorded in the OBF of anesthetized rats by means of tungsten fiber multibarreled glass microelectrodes during microelectrophoretic administration of IL-1beta. More than half (56%) of all cells tested changed in firing rate in response to IL-1beta. Approximately 90% of these cytokine-modulated neurons were also sensitive to microelectrophoretically applied d-glucose, that is, proved to be the elements of the central glucose-monitoring neural network. The present findings demonstrate that IL-1beta can exert direct modulatory role on neurons in the OBF.

Interleukin-1 beta exerts a myriad of effects in the brain and in particular in the hippocampus: analysis of some of these actions

The realization, in the past decade or so, that bidirectional communication between the central nervous system and the immune system was likely has sparked an explosion of interest in the roles certain cytokines, particularly the proinflammatory cytokine interleukin-1 beta (IL-1 beta), might play in the brain. The observation that IL-1 type I receptor was expressed in highest density in the hypothalamus was of significance in identifying a role for IL-1 beta in neuroendocrine modulation. However, the finding that receptor expression was also high in the hippocampus, an area of the brain which plays a pivotal role in memory and learning, has led to uncovering a role for IL-1 beta in cognitive function. There is now a great deal of evidence suggesting that IL-1 beta plays a significant role in hippocampal synaptic function, and the possibility that IL-1 beta may trigger some of the detrimental changes in certain neurodegenerative diseases is currently being assessed. The review addresses some of the issues relating to the role of IL-1 beta in the brain, specifically in the hippocampus.

Activation of astrocyte intracellular signaling pathways by interleukin-1 in rat primary striatal cultures

The striatum has been implicated as the site of action mediating neurotoxic effects of interleukin-1 (IL-1) during ischemia. However, the molecular mechanisms underlying these events have yet to be fully addressed. In the present study, primary cultures of rat striatal cells were used as a model for the study of IL-1 signaling pathways in the striatum. Immunocytochemical analyses revealed that these cultures consisted of a mixture of neurones and astrocytes and demonstrated expression of the IL-1 type I receptor (IL-1RI) on both cell types. Treatment with IL-1 (3 units/ml) for 10 min increased phosphorylation of p38 MAP kinase in striatal cells. The endogenous IL-1RI inhibitor IL-1Ra (24 ng/ml) and the p38 MAP kinase inhibitor SB203580 (10 nM) both inhibited this response. Analysis of the effects of IL-1 on nuclear translocation of the transcription factor NF-kB revealed that NF-kB became activated in a time-dependent manner. Immunocytochemistry revealed that IL-1 stimulated p38 phosphorylation and NF-kB translocation in astrocytes only. TaqMan real-time quantitative PCR analysis revealed that IL-1 stimulated gene expression of tumor necrosis factor-alpha (TNF) in striatal cultures. The p38 MAP kinase inhibitor SB203580 failed to inhibit the effects of IL-1 on NF-kB translocation or gene transcription. These studies have demonstrated significant aspects of the IL-1 signaling cascade in cultured striatum. Of particular interest is the finding that IL-1 stimulated activation of p38 MAP kinase and NF-kB in striatal astrocytes exclusively.

Interleukin-1 beta, but not IL-1 alpha, mediates nerve growth factor secretion from rat astrocytes via type I IL-1 receptor

In astrocytes, nerve growth factor (NGF) synthesis and secretion is stimulated by the cytokine interleukin-1 beta (IL-1 beta). In the present study, the role of IL-1 receptor binding sites in the regulation of NGF release was evaluated by determining the pharmacological properties of astroglially localized IL-1 receptors, and, by comparing the effects of both the agonists (IL-1 alpha and IL-1 beta) and the antagonist (IL-1ra)-members of the IL-1 family on NGF secretion from rat neonatal cortical astrocytes in primary culture. Using receptor-binding studies, binding of [(125)I] IL-1 beta to cultured astrocytes was saturable and of high affinity. Mean values for the K(D) and B(max) were calculated to be 60.7+/-7.4 pM and 2.5+/-0.1 fmol mg(-1) protein, respectively. The binding was rapid and readily reversible. IL-1 receptor agonists IL-1 alpha (K(i) of 341.1 pM) and IL-1 beta (K(i) 59.9 pM), as well as the antagonist IL-1ra (K(i) 257.6 pM), displaced specific [(125)I] IL-1 beta binding from cultured astrocytes in a monophasic manner. Anti-IL-1RI antibody completely blocked specific [(125)I] IL-1 beta binding while anti-IL-1RII antibody had no inhibitory effect. Exposure of cultured astrocytes to IL-1 alpha and IL-1 beta revealed the functional difference between the agonists in influencing NGF release. In contrast to IL-1 beta (10 U/ml), which caused a 3-fold increase in NGF secretion compared to control cells, IL-1 alpha by itself had no stimulatory action on NGF release. The simultaneous application of IL-1 alpha and IL-1 beta elicited no additive response. IL-1ra had no effect on basal NGF release but dose-dependently inhibited the stimulatory response induced by IL-1 beta. We concluded that IL-1 beta-induced NGF secretion from cultured rat cortical astrocytes is mediated by functional type I IL-1 receptors, whereas IL-1 alpha and IL-1ra, in spite of their affinity for IL-1RI, have no effect on NGF secretion from these cells. Type II IL-1R is not present on rat neonatal cortical astrocytes.

Interleukin-6 expression and regulation in rat enteric glial cells

As yet, little is known about the function of the glia of the enteric nervous system (ENS), particularly in an immune-stimulated environment. This prompted us to study the potential of cultured enteroglial cells for cytokine synthesis and secretion. Jejunal myenteric plexus preparations from adult rats were enzymatically dissociated, and enteroglial cells were purified by complement-mediated cytolysis and grown in tissue culture. Cultured cells were stimulated with recombinant rat interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha, and IL-6 mRNA expression and secretion were assessed using RT-PCR and a bioassay, respectively. Stimulation with TNF-alpha did not affect IL-6 mRNA expression, whereas IL-1beta stimulated IL-6 mRNA and protein synthesis in a time- and concentration-dependent fashion. In contrast, IL-6 significantly and dose-dependently suppressed IL-6 mRNA expression. In summary, we have presented evidence that enteric glial cells are a potential source of IL-6 in the myenteric plexus and that cytokine production by enteric glial cells can be regulated by cytokines. These findings strongly support the contention that enteric glial cells act as immunomodulatory cells in the enteric nervous system.

Astrocytic Fos expression in the rat posterior pituitary following LPS administration

Systemic lipopolysaccharide (LPS) administration has been shown to cause profound Fos expression in multiple regions of the brain. In the present experiment, Fos expression in the hypothalamic supraoptic nucleus (SON), posterior pituitary, and anterior pituitary was investigated using quantitative immunohistochemistry. In the SON and anterior pituitary, a large number of Fos-positive cells were observed by restraint stress, hyperosmotic administration (1.5, 3, and 9% NaCl), and LPS administration (5, 25, and 125 microg/kg). In the posterior pituitary, LPS administration caused a significant increase in the number of Fos-positive nuclei in a dose-dependent manner, whereas restraint stress and hyperosmotic stimulation (1.5 and 3% NaCl) did not increase the number of Fos-positive cells and 9% NaCl administration induced weak Fos immunoreactivity. Moreover, a dual-labeling study using a confocal microscope revealed that Fos-positive cells in the posterior pituitary were astrocytes using MAP2, an astrocytic marker in the posterior pituitary. Here, we demonstrated that the astrocytes of the posterior pituitary expressed Fos in response to LPS administration, which suggests that Fos expression participates in the activation of astrocytes during acute-phase responses with LPS administration.

Clinical relevance of cytokine production in hemodialysis

Blood-dialyzer interaction in hemodialysis has the potential to activate mononuclear cells leading to the production of inflammatory cytokines. The extent of activation is dependent on the dialyzer material used and is considered an index of biocompatibility. Cytokines, such as interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), and IL-6, may induce an inflammatory state and are believed to play a significant role in dialysis-related morbidity. The interleukin hypothesis suggests that the release of proinflammatory cytokines acts as an underlying pathophysiologic event in hemodialysis-related acute manifestations, such as fever and hypotension. Nevertheless, a cytokine overproduction may alter sleep pattern in chronic hemodialyzed patients, thus explaining the presence of sleep disorders in these patients. A potential role of cytokines in chronic-related morbidity has also been suggested. High levels of some inflammatory cytokines are often associated with anemia caused by hyporesponsiveness to erythropoietin. Cytokine production may also play a relevant role in bone remodeling by regulating osteoblast/osteoclast cell functions and parathyroid hormone (PTH). Finally, cytokine release may have a long-term deleterious effect on mortality of uremic patients by altering immune response and increasing susceptibility to infections. Bioincompatibility of dialytic membranes may also contribute to malnutrition in dialysis patients by increasing the monocyte release of catabolic cytokines such as TNF-alpha and IL-6. Bioincompatible dialytic treatment may induce an inappropriate monocyte activation and cytokine production, which, in turn, may mediate some of the immune and metabolic dysfunction associated with hemodialysis. The use of biocompatible dialytic membranes appears to reduce the monocyte activation and to improve the survival of hemodialysis patients.

IL-1beta immunoreactive neurons in the human hypothalamus: reduced numbers in multiple sclerosis

Corticotropin-releasing hormone (CRH)-containing neurons in the paraventricular nucleus (PVN) in the hypothalamus of multiple sclerosis (MS) patients are hyperactivated. Since interleukin-1 (IL-1)beta is a powerful activator of CRH neurons, its immunohistochemical expression was studied in the postmortem hypothalamus of MS patients (n=11) and matched controls (n=11). Hypothalamic tissue of 10/11 MS patients showed demyelinating lesions that in many cases contained IL-1beta-immunoreactive (ir) macrophages and glial cells. In control subjects IL-1beta-ir was only sporadically found in glial cells. Interestingly, abundant IL-1beta-ir was also present in hypothalamic neurons. Neuronal IL-1beta co-localised with oxytocin and not with vasopressin or CRH. IL-1beta clearly yielded a less intense staining in neurons and numbers of IL-1-ir neurons in the PVN were 4.5-fold reduced in MS. We suggest that IL-1beta produced by activated glial cells in the hypothalamus of MS patients may contribute to the activation of the hypothalamic CRH neurons, while reduced expression of neuronal IL-1beta in MS patients may have consequences for neuroendocrine, behavioural or autonomic functioning.

Cytosensor techniques for examining signal transduction of neurohormones

This review describes the principles of microphysiometry and how they can be applied, using the Cytosensor, to the investigation of the signal transduction mechanisms activated by both G-protein and non-G-protein coupled hormone and neuropeptide receptors. The use of the Cytosensor to study desensitisation and cross-talk is also discussed, as are the benefits and limitations of this technique.Key words: Cytosensor, microphysiometry, signal transduction, neuropeptides, hormones.