Protective effect of the interleukin-1 receptor antagonist (IL-1ra) on experimental allergic encephalomyelitis in rats

Cytokines such as interleukin-1 (IL-1) are thought to contribute to the inflammatory response associated with autoimmune diseases like multiple sclerosis. We assessed the role of IL-1 in an animal model of MS, experimental allergic encephalomyelitis (EAE), by testing the effects of treatment with an IL-1 receptor antagonist (recombinant human IL-1ra) on the clinical course of EAE in Lewis rats. Treatment with rhIL-1ra every day starting on Day 9 post-immunization with myelin basic protein (MBP) during the effector phase of EAE significantly inhibited clinical signs of EAE. rhIL-1ra delayed the onset, reduced the severity of paralysis and weight loss, and shortened the duration of disease. These data suggest that IL-1 is a mediator of the inflammation resulting from active immunization with MBP, and that inhibitors of IL-1 may prove beneficial for the treatment of autoimmune or inflammatory diseases of the central nervous system.     

人IL—1,IL—1ra及IL—6在人胚雪旺细胞中的表达

分别用LRBM33Ia5、HT－2和KD83细胞株检测人胚雪旺细胞（SC）IL-1和IL-6分泌水平，用原位杂交技术检测上述细胞因子及白细胞介素-1受体拮抗剂（IL－1ra）的mRNA表达。结果表明：人胚雪旺细胞能自发分泌IL－1及IL－6活性蛋白，24h在培养上清中即可出现IL－1和IL－6活性，72h分泌达高峰，IL－1和IL－6分泌水平分别为26．30±8．10和57．40±12．40U／ml；人胚雪旺细胞具有IL－1、IL－1ra及IL－6mRNA的表达。提示IL－1、IL－1ra及IL－6可能参与神经系统的发育、修复等过程。     

Androgen-dependent vasopressinergic neurotransmission attenuates interleukin-1-induced sickness behavior

Castrated male rats were found to be more sensitive than intact male rats to the depressing effects of recombinant human interleukin-1 beta (Il-1) on social exploration. This was the case whether Il-1 was injected acutely (1-5 micrograms/rat, i.p.) or continuously, via an implanted osmotic mini-pump (2 micrograms Il-1 per day). In this latter case, tolerance developed more rapidly to the behavioral effects of Il-1 than to its effects on body weight. Since there is evidence that extrahypothalamic arginine vasopressin (AVP) acts as an endogenous antipyretic in the brain and the local concentration of AVP is dependent on circulating androgens, we tested the hypothesis that the enhanced sensitivity of male rats to the behavioral effects of Il-1 was caused by a reduced brain concentration of vasopressin. Central injection of AVP (2.5 ng, i.c.v.) attenuated the behavioral effects of Il-1 (5 ng, i.c.v.) and this effect was more marked in castrated than in intact male rats. Conversely, central injection of an antagonist of the vasopressor receptors of AVP, dPTyr(Me)AVP (15 ng, i.c.v.) potentiated the behavioral effects of Il-1 (1 ng, i.c.v.) in intact but not in castrated male rats. These results are consistent with the possibility that androgen-dependent vasopressinergic neurons oppose the neural effects of Il-1.     

Effects of serotonin synthesis blockade on interleukin-1β action in the brain of rats

The ability of the brain serotonergic system to mediate the effects of interleukin-1β (IL-1β) was investigated. Intracerebroventricular administration of IL-1β induced a significant pyrogenic reaction, depression in social behaviour, loss of body weight and reduced food intake in rats. Pre-treatment with p-chlorphenylalanine, an inhibitor of serotonin synthesis, blocked the IL-1β-induced decrease in food intake and loss of body weight, but failed to alter the temperature increase and the decrease in communicative activity.     

Morphological and behavioral changes induced by transgenic overexpression of interleukin-1ra in the brain

Interleukin-1 (IL-1) has a peak of expression in the brain in a period of maximal network reorganization and then virtually disappears from the normal adult brain. The aim of our study was to identify phenotypical alterations induced by chronically blocking IL-1 signalling. We used homozygous transgenic mice overexpressing human soluble IL-1ra and age-matched wild-type mice. We used littermates from litters obtained by mating heterozygous transgenic progenitors, and animals with predetermined genotype (nonlittermates). In littermates, the genotype was identified after the experiments had been completed. The mice were tested at the ages of 6 and 12 months with a battery of tests, including dark-light preference, footprint/gait analysis, and analysis of motor performance during swimming. MR imaging was performed on formalin-fixed brains; total and relative volumes of cortical and subcortical structures were estimated stereologically on the acquired images. Multivariate data analysis (PLS-DA) of the behavioral data showed separation between nonlittermate wild-type and transgenic mice at both 6 and 12 months, whereas the littermates displayed a more homogenous behavioral profile. The PLS-DA model for brain morphology showed a clear separation between wild-type and transgenic mice as well as between transgenic littermates and nonlittermates. Regression analysis by means of partial least squares (PLS) showed that the brain morphology accounts for the behavioral profile in a significant proportion (16.9%). In conclusion, we show that IL-1 signalling is important for normal development of the brain, and the initial alteration resulting from prenatal exposure to IL-1ra can be recovered provided that the IL-1 signalling pathway is intact.     

慢性应激对大鼠行为和体重的影响

目的　观察慢性应激对大鼠行为和体重的影响。方法　采用慢性强迫游泳模型 ,应用行为追踪仪观察大鼠的活动量 ,以电子动物称监测大鼠体重变化。结果　应激组大鼠活动量明显高于对照组 (P <0 0 1) ,排便、排尿增加 ,修饰频繁。应激组大鼠体重增长明显低于对照组 (P <0 0 1)。结论　慢性强迫游泳使大鼠活动量增多 ,抑制体重增长。     

Interleukin-1β induced corticosterone elevation and hypothalamic NE depletion is vagally mediated

Processes occurring within the immune system can alter neural function. Cytokines released by cells of the immune system during illness are key messengers in immune-to-brain communication. Interleukin-1β (IL-1β) is particularly important in this regard and is known to stimulate a myriad of illness-related outcomes such as fever, sickness behavior, aphagia, adipsia, hypothalamic-pituitary-adrenal activation, and changes in pain reactivity. Thus peripherally released IL-1β has potent neural effects and is a critical mediator of the impact of immune processes on brain. There is, however, uncertainty concerning the communication pathways involved. We provide evidence that a primary route of peripheral cytokine signalling is through stimulation of peripheral vagal afferents rather than or in addition to direct cytokine access to brain. Subdiaphragmatic, but not hepatic vagotomy, blocked rhIL-1β-induced hypothalamic norepinephrine depletion and attenuated rhIL-1β-induced increases in serum corticosterone. These data suggest that rhIL1-β activates the hypothalamic-pituitary-adrenal axis via stimulation of peripheral vagal afferents and further support the hypothesis that peripheral cytokine signalling to the CNS is mediated primarily by stimulation of peripheral afferents.     

白细胞介素1受体拮抗剂对大鼠外伤性脑水肿的治疗作用

目的 观察白细胞介素1受体拮抗剂(IL—1ra)对于外伤性脑水肿的影响。方法 液压伤致大鼠外伤性脑水肿。伤后脑室注射IL-1ra。伤后24h磁共振，脑组织干湿重，HE病理图像分析及电镜等方法观察鼠脑水肿情况。结果 经IL-1ra治疗，与创伤组或治疗对照组相比在磁共振T2加权像上可以水肿减轻；创伤部位脑含水量减低；病理切片可见相同的变化；超微病理发现IL—1ra具有保护作用。结论 IL-1ra对于外伤性脑水肿有治疗作用，内源性IL-1参与了外伤性脑水肿的发生。     

Intracerebroventricular interleukin-1 receptor antagonist blocks the enhancement of fear conditioning and interference with escape produced by inescapable shock

Brain interleukin-1 (IL-1) plays a key role in mediating the neural, endocrine, and behavioral consequences of injury and infection. Recent evidence indicates that brain IL-1 may also be important in producing endocrine and neurochemical responses to stressors. The present experiment sought to determine whether intracerebroventricular (i.c.v.) administration of an interleukin-1 receptor antagonist (IL-1ra) would block behavioral effects of a stressor. I.c.v. application of hrIL-1ra before inescapable shock blocked the subsequent interference with escape learning and enhancement of fear conditioning normally produced by this treatment.     

Different receptor mechanisms mediate the effects of endotoxin and interleukin-1 on female sexual behavior

Activation of the immune system by lipopolysaccharide (LPS) produces physiological, neuroendocrine and behavioral effects, some of which are mediated by cytokine production. We have previously shown that the cytokine interleukin-1 (IL-1) inhibits sexual behavior in female, but not male rats, while producing a comparable suppression of locomotion in both sexes. The present study examined the effects of LPS on sexual behavior and locomotion of male and female rats, and the involvement of IL-1 receptors in mediating the effects of IL-1 and LPS on females' behavior. Peripheral (i.p.) administration of LPS (50 or 250 μg/kg) significantly decreased sexual behavior in females, up to 6 h after administration, while it had no effect on male sexual behavior. However, locomotor activity, measured in the open-field test, was similarly reduced by LPS in both males and females. Pretreatment with the IL-1 receptor antagonist (IL-1ra) either i.p. (10 mg/kg) or intracerebroventricularly (i.c.v.) (50 μg/rat) did not prevent the inhibition of female sexual behavior and locomotion induced by either i.p. (50 μg/kg) or i.c.v. (200 or 400 ng/rat) administration of LPS, respectively. However, identical doses of IL-1ra significantly reversed the effects of IL-1β, administered either i.p. (5 μg/kg) or i.c.v. (50 ng/rat), respectively. These results demonstrate that both LPS and IL-1β produce marked inhibition of sexual behavior in female, but not in male rats. However, IL-1 receptors are not required for the effects of LPS on sexual behavior in female rats.     

Immune system genes in multiple sclerosis: genetic association and linkage analyses on TCRβ, IGH, IFN-γ and IL-1ra/IL-1β loci

The role of genetic factors in the etiology of multiple sclerosis (MS) has been clearly demonstrated but the loci determining susceptibility to this disease remain largely unidentified. A contribution from several immune system genes has been suggested based on animal models and association/linkage analyses on MS patients and families. With the exception of the findings from the HLA complex, studies on candidate immune system genes have provided controversial results. Here we have performed genetic association and linkage analyses on four chromosomal regions containing immune system genes. A possible role for each of these loci in MS has been previously suggested. In data-sets derived from the Finnish population we found no evidence for contribution of the T-cell receptor β chain (TCRβ chromosome 7q35), immunoglobulin heavy chain (IGH chromosome 14q32), interferon-γ (IFN-γ chromosome 12q14-q15) or interleukin-1 receptor antagonist/interleukin-1β (IL-1ra/IL-1β chromosome 2q14-q21) loci in the genetic susceptibility to MS.     

Inflammatory markers are associated with inhibitory avoidance memory deficit induced by sleep deprivation in rats

Sleep deprivation (SD) causes detrimental effects to the body, such as memory impairment and weight loss. SD also changes the concentration of inflammatory mediators such as cytokines, which, in turn, can affect cognitive functioning. Thus, the objective of this study was to investigate the involvement of these inflammatory mediators in inhibitory avoidance memory deficit in sleep-deprived rats. Male Wistar rats were deprived of sleep by the modified multiple platform method for 96 h, while their respective controls remained in their housing cages. To assess memory after SD, all animals underwent training, followed by the inhibitory avoidance task test 24 h later. Also, the weight of each animal was recorded daily. In the first experiment, animals received an acute administration of lipopolysaccharide (LPS, 50 or 75 μg/kg i.p.) 3 h before the inhibitory avoidance training. In the experiment 2, the animals received acute or chronic administration of anti-IL-6 antibody (Ab, 2 μg/kg i.p.). The acute administration was performed 3 h before the inhibitory avoidance training, while the chronic treatment administrations were performed daily during the SD period. The 75 μg/kg dose of LPS, but not the 50 μg/kg dose, caused a significant attenuation of memory impairment in the sleep-deprived animals. Although the treatments with the anti-IL-6 Ab did not produce any significant changes in cognitive performance, the Ab attenuated weight loss in sleep-deprived animals. Taken together, these results suggest the involvement of inflammatory mediators in the modulation of memory deficit and weight loss that are observed in sleep-deprived rats.     

雌二醇与氟西汀对大鼠体质量及在强迫游泳实验中行为的影响

目的观察雌二醇与氟西汀对去卵巢大鼠体质量及在强迫游泳实验（FST）中行为的影响。方法将42只雌性SD大鼠随机分为去卵巢组（OVX）与假手术组（Sham）,根据药物干预不同,OVX组分为油剂对照组（oil）、雌二醇组（E2）、氟西汀组（FLX）和雌二醇＋氟西汀组（E2＋FLX）,假手术组分为生理盐水组（NS）和氟西汀组（FLX）,每组7只。去卵巢手术与假手术后饲养3周,从第4周开始慢性给药14d,第15d进行15min FST并摄像,行为学分析。隔天称量、记录大鼠体质量。结果（1）在绝经模型建立期,OVX组体质量增长[（54．3±15．1）g]显著高于Sham组[（30．8±11．0）g]（t=5．16,P〈0．01）。（2）在药物干预期,OVX4-FLX组体质量减轻显著高于OVX4-FLX＋E2组（H=25．96,P〈0．001）。（3）E2、FLX、E24-FLX可显著增加大鼠在15minFST中游泳行为（F5-34=62．80,P〈0．001）,减少不动行为（F5.34=14．47,P〈0．001）。（4）OVX4-Oil组不动行为在15rainFST前中后三个5min内逐阶段显著增加（F2．18=30．90,P〈0．001）。结论在FST中,E2有类似FLX-样的抗抑郁样作用,E2可减弱去卵巢大鼠体质量波动的程度。     

多发性硬化与白细胞介素-1关系初步研究

目的探讨白细胞介素-1(IL-1),尤其是白细胞介素-1β(IL-1β)和白细胞介素-1受体拮抗剂(IL-1RA)基因多态性及IL-1β血清含量与东北地区汉族多发性硬化(M S)的关系。方法多聚酶链反应(PCR)对54例M S患者的血清进行IL-1β和IL-1RA基因多态性检测;酶联免疫吸附实验检测血清中IL-1β含量。结果IL-1β和IL-1RA基因型分布及等位基因频率在M S和对照组间无显著性差异(P>0.05)。IL-1β血清含量M S组比对照组显著增高(P<0.05)。结论IL-1β和IL-1RA基因多态性与M S易感性可能无相关性。IL-1β可能在M S发病中起到促进作用,参与启动炎症过程和组织损伤。     

Role of IL-1 in poststroke depressive-like behavior in mice.

BACKGROUND: Poststroke depression (PSD) leads to impaired functional recovery and increased mortality, yet physiological mechanisms are unknown. The present study investigates the roles of glucocorticoids and interleukin-1 (IL-1) in poststroke anhedonia. METHODS: Adult male mice underwent middle cerebral artery occlusion (MCAO), and were recovered 7 days. Mice were treated with metyrapone (100 mg/kg intraperitoneally), mifepristone (50 mg/kg subcutaneously), or vehicle injections on reperfusion days 4-7. A separate cohort of mice was implanted with cannulae and was administered IL-1 receptor antagonist (IL-1ra) or vehicle (6 microg intracerebroventricularly) on reperfusion days 6 and 7. After the final injection or infusion, sucrose consumption was recorded for 6 hours. RESULTS: Mice in the sham-treated group consumed significantly more sucrose solution than water, whereas MCAO-treated mice consumed similar amounts of each, suggesting anhedonia among MCAO-treated mice. A separate experiment assessed whether stroke-induced increases in corticosteroids or IL-1 contribute to anhedonia. Only IL-1ra restored sucrose consumption in MCAO-treated mice. Vehicle-MCAO-treated mice drank significantly less sucrose solution than did both IL-1ra and vehicle-sham treatment groups, whereas IL-1ra-MCAO-treated mice drank similar amounts to both sham-treated groups. CONCLUSIONS: Poststroke anhedonia, a symptom of depression in human beings, can be reproduced in a mouse model of stroke and appears to involve altered IL-1 transmission in the brain.     

Lasting changes in social behavior and amygdala function following traumatic experience induced by a single series of foot-shocks

Neuronal plasticity within the amygdala mediates many behavioral effects of traumatic experience, and this brain region also controls various aspects of social behavior. However, the specific involvement of the amygdala in trauma-induced social deficits has never been systematically investigated. We exposed rats to a single series of electric foot-shocks - a frequently used model of trauma - and studied their behavior in the social avoidance and psychosocial stimulation tests (non-contact versions of the social interaction test) at different time intervals. Social interaction-induced neuronal activation patterns were studied in the prefrontal cortex (orbitofrontal and medial), amygdala (central, medial, and basolateral), dorsal raphe and locus coeruleus. Shock exposure markedly inhibited social behavior in both tests. The effect lasted at least 4 weeks, and amplified over time. As shown by c-Fos immunocytochemistry, social interactions activated all the investigated brain areas. Traumatic experience exacerbated this activation in the central and basolateral amygdala, but not in other regions. The tight correlation between the social deficit and amygdala activation patterns suggest that the two phenomena were associated. A real-time PCR study showed that CRF mRNA expression in the amygdala was temporarily reduced 14, but not 1 and 28 days after shock exposure. In contrast, amygdalar NK1 receptor mRNA expression increased throughout. Thus, the trauma-induced social deficits appear to be associated with, and possibly caused by, plastic changes in fear-related amygdala subdivisions.     

The effects of interleukin-1 receptor antagonist protein (IRAP) infusion following spinal cord transection in rats

A laminectomy was performed at the T5−T6 vertebral level in adult, male, Sprague-Dawley rats and the spinal cord transected with a scalpel. A group of sham animals was subjected to the same surgery without the transection step. A group of unhandled control rats was also included. A subgroup of transected animals received a subcutaneous osmotic minipump that dispensed IL-1 receptor antagonist protein (IRAP) at the transection site for 7 consecutive days. Another transected subgroup received a minipump that infused the vehicle only. IRAP-treated rats displayed a significant reduction in body temperature (p<0.05) compared with vehicle-treated rats. The IRAP-treated rats were also less active when assessed for locomotor behavior using an HVS computerized tracking system (p<0.01). IRAP treatment had no effect on serum corticosterone, β-endorphin levels, Con A, PHA, or LPS-induced splenocyte mitogenesis when compared with vehicle-treated animals. However, half of the IRAP-treated animals exhibited a substantive reduction in the number of reactive astrocytes near the transection site, suggesting a possible effect of IRAP on astrocyte activation.     

Differential effects of CB1 neutral antagonists and inverse agonists on gastrointestinal motility in mice

Background Cannabinoid type 1 (CB₁) receptors are involved in the regulation of gastrointestinal (GI) motility and secretion. Our aim was to characterize the roles of the CB₁ receptor on GI motility and secretion in vitro and in vivo by using different classes of CB₁ receptor antagonists. Methods Immunohistochemistry was used to examine the localization of CB₁ receptor in the mouse ileum and colon. Organ bath experiments on mouse ileum and in vivo motility testing comprising upper GI transit, colonic expulsion, and whole gut transit were performed to characterize the effects of the inverse agonist/antagonist AM251 and the neutral antagonist AM4113. As a marker of secretory function we measured short circuit current in vitro using Ussing chambers and stool fluid content in vivo in mouse colon. We also assessed colonic epithelial permeability in vitro using FITC‐labeled inulin. Key Results In vivo, the inverse agonist AM251 increased upper GI transit and whole gut transit, but it had no effect on colonic expulsion. By contrast, the neutral antagonist AM4113 increased upper GI transit, but unexpectedly reduced both colonic expulsion and whole gut transit at high, but not lower doses. Conclusions & Inferences Cannabinoid type 1 receptors regulate small intestinal and colonic motility, but not GI secretion under physiological conditions. Cannabinoid type 1 inverse agonists and CB₁ neutral antagonists have different effects on intestinal motility. The ability of the neutral antagonist not to affect whole gut transit may be important for the future development of CB₁ receptor antagonists as therapeutic agents.