5-HT2A-mu opioid receptor mechanisms in the hypothalamus mediate interleukin-1beta fever in rats

Direct administration of interleukin-1beta (IL-1beta) into the lateral cerebral ventricle of rat brain, in addition to inducing febrile responses, upregulated the immunoreactivity of tryptophan hydroxylase in the preoptic anterior hypothalamus. The fever induced by IL-1beta was significantly attenuated by pretreatment with intracerebroventricular injection of 5-HT2A receptor antagonists including cyproheptadine, ketanserin, or mianserin. In addition, the IL-1beta-induced fever was mimicked by intracerebroventricular administration of a 5-HT2A receptor agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-amionpropane (DOI). The DOI-induced (present results) or IL-1beta-induced (previous results) fever was further attenuated by pretreatment with an intracerebroventricular dose of mu-opioid receptor antagonists (e.g., buprenorphine or cyclic d-phe-cys-Try-d-Arg-Thr-pen-Thr-NH2) or 5-HT receptor antagonists (e.g., ketanserin or cyproheptadine). These findings suggest that a 5-HT2A-mu opioid receptor mechanism in the hypothalamus may mediate the IL-1beta fever.

Neuropeptides (SP and CGRP) augment pro-inflammatory cytokine production in HSV-infected macrophages

Neuropeptides are able to modulate cytokine production by macrophages in response to various stimulators. In this study, the effects of neuropeptides substance P (SP) and calcitonin gene-related peptide (CGRP) on production of pro-inflammatory cytokines TNF and IL-1 beta by macrophages were considered. Mouse peritoneal macrophages were infected with herpes simplex virus type-1 (HSV-1), or remained unstimulated, and cytokine assays were performed after 12 h. IL-1 beta and TNF secretion by unstimulated macrophages have been significantly increased in the presence of SP and CGRP. Each neuropeptide, alone or in coordination with the other, caused significant increase in IL-1 beta and TNF production by HSV-infected mouse peritoneal macrophages. It was concluded that the macrophage-mediated inflammatory response to HSV-1 is enhanced in the presence of these neuropeptides.

Selective increase in TNF alpha permeation across the blood-spinal cord barrier after SCI

We generated a novel mouse model of spinal cord injury (SCI) by hemisection of the right L1 lumbar spinal cord, measured the permeability of the blood-spinal cord barrier (BSCB), and tested the hypothesis that tumor necrosis factor alpha (TNF alpha) penetrates the injured BSCB by an enhanced transport system. SCI produced stereotypical sensorimotor deficits resembling the classically described Brown-Seqúard syndrome. Disruption of the BSCB was reflected by increased spinal cord uptake of radiolabeled albumin from blood; this was transient (immediately after SCI) and confined to the lumbar spinal cord. By contrast, specific increase in the entry of TNF alpha was detected in brain, cervical, thoracic, and lumbar spinal cord at 1 week after SCI, in addition to its immediate and transient increase consistent with barrier disruption. Lack of a second peak of increase in the entry of IL1 beta further supported the specificity of the TNF alpha response. Moreover, enhanced uptake of radiolabeled TNF alpha was suppressed by excess non-radiolabeled TNF alpha, indicating competition of entry via the known transport system for TNF alpha. Therefore, upregulation of the transport system after SCI probably mediates the increased permeation of TNF alpha across the BSCB. Enhanced entry of TNF alpha at 1 week after SCI was concurrent with sensorimotor and gait improvement of the mouse. We conclude that SCI by lumbar hemisection activates the transport system for TNF alpha at the BBB and suggest that selective permeation of TNF alpha may facilitate functional recovery.

Procalcitonin and proinflammatory cytokine clearance during continuous venovenous haemofiltration in septic patients

Procalcitonin (PCT), interleukin-6 (IL-6), tumour necrosis factor a (TNFalpha), and interleukin-1beta (IL-1beta) are important clinical prognostic markers in ICU septic patients. The goal of the study was to determine whether continuous venovenous haemofiltration (CWH), using an AN69 haemofilte, leads to elimination of PCT, TNFalpha, IL-6 and IL-1beta in 13 septic patients with multi-organ failure. At the start of haemofiltration (0), 6 and 12 hours the mean afferent plasma concentration +/- SD of PCT (10.1 +/- 9.1, 7 +/- 6, 5.9 +/- 5.7 ng/ml), IL-6 (804.6 +/- 847.6, 611.7 +/- 528.4, 575.2 +/- 539.2 pg/ml), and that of TNFalpha (4.5 +/- 2.6, 4 +/- 3.1, 3.8 +/- 2.9 pg/ml) significantly declined during CVVH. The efferent plasma concentrations were significantly lower than the corresponding afferent concentrations. PCT; IL-6 and TNFalpha were detectable in the ultrafiltrate of all patients. IL-1beta was only detectable in the plasma of eight patients and the ultrafiltrate of five patients. The plasma clearance of PCT, IL-6 and TNFalpha significantly decreased after 12 hours as a result of a decline in the adsorptive elimination of the mediators due to progressive membrane saturation. We demonstrated that if PCT, IL-6 and TNFalpha are used as clinical prognostic markers in septic patients who are treated with CWIH using an AN69 membrane, one should be aware that their plasma level could be modified by the therapy. In addition CWH could represent an appropriate tool to remove a broad spectrum of proinflammatory mediators, if such removal is required in septic patients.

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.

1,25-dihydroxyvitamin D3 differentially regulates IL-1alpha-stimulated IL-8 and MCP-1 mRNA expression and chemokine secretion by human primary proximal tubular epithelial cells

Beside its role in calcium homeostasis, 1,25-D3 modulates multiple immunological functions in cells of the immune system. In tubular epithelial cells, it increases the expression of HLA-DR and ICAM-1 molecules. Since production of chemokines, such as IL-8 and MCP-1, by tubular epithelial cells is crucial for the inflammatory response in acute transplant rejection and interstitial nephritis, we tested whether 1,25-D3 influences the production of IL-8 and MCP-1 by primary human tubular epithelial cells (TEC). For chemokine detection we used enzyme-linked immunosorbent assays. We differentiated between chemokine secretion directed to the apical and basolateral environment by using cell culture inserts as a model for the tubular basement membrane. mRNA of IL-8 and MCP-1 after stimulation of TEC with IL-1alpha and/or 1,25-D3 was isolated and compared by competitive RT-PCR. We found that basolateral production of IL-8 was higher than luminal secretion. 1,25-D3 (10(-8) M) alone and in combination with IL-1alpha suppressed IL-8 production after 48 h. Basolateral compared to luminal MCP-1 secretion was higher after stimulation either with IL-1alpha alone or combined with 1,25-D3. After 72 h, 1,25-D3 enhanced the IL-1alpha-stimulated MCP-1 secretion. Increased IL-8 mRNA expression after stimulation with IL-1alpha was suppressed by coincubation with 1,25-D3, while MCP-1 mRNA synthesis was enhanced by 1,25-D3 alone and in combination with IL-1 alpha. We conclude that 1,25-D3 differently modulates the expression of CXC-chemokine IL-8 and CC-chemokine MCP-1 by human TEC. The differential effects of 1,25-D3 on renal tubular cytokine secretion have to be considered in therapeutic dials on this hormone, e.g. in renal transplant rejection.

Diffusion and action of intracerebroventricularly injected interleukin-1 in the CNS

Interleukin-1beta acts on the CNS to induce fever, neuroendocrine activation and behavioural depression. We have previously demonstrated that interleukin-1beta is synthesized in glial cells and macrophages of circumventricular organs and choroid plexus after intraperitoneal administration of bacterial lipopolysaccharide. Whether, and how, interleukin-1beta produced in glial cells affects neuronal functioning is unknown. Diffusion throughout the extracellular space is an important pathway by which factors produced by glial cells act on distant cells, a phenomenon coined "volume transmission". The present study assessed diffusion of recombinant rat interleukin-1beta, recombinant human interleukin-1 receptor antagonist and 10mol. wt dexran in the rat CNS after intracerebroventricular administration to model interleukin-1beta release from choroid plexus. Immunocytochemistry with specific antibodies directed against interleukin-1beta and interleukin-1 receptor antagonist revealed that these molecules rapidly penetrated into periventricular tissue and spread along white matter fibre bundles and blood vessels in the caudoputamen, hypothalamus and amygdala. The transcription factor nuclear factor kappa B and the immediate-early gene product Fos were detected immunocytochemically to reveal interleukin-1beta action. Intracerebroventricular infusion of interleukin-1beta induced nuclear factor kappa B translocation in choroid plexus, ependymal cells, basolateral amygdala, cerebral vasculature and meninges. Fos immunoreactivity was found in the supraoptic and paraventricular hypothalamus and central amygdala. We propose that intracerebroventricular injected interleukin-1beta can enter the brain parenchyma and act as a "volume transmission" signal in, for example, the basolateral amygdala where it might activate a neuronal projection to the central amygdala.

Disruption of the blood-aqueous barrier following retinal laser photocoagulation and cryopexy in pigmented rabbits

Disruption of the blood-aqueous barrier (BAB) induced by retinal photocoagulation and cryopexy in pigmented rabbits was evaluated by laser flare photometry. A significant increase in flare values after retinal photocoagulation was measured from the 1st postoperative day, with values returning to baseline levels by day 7. Cryopexy induced consistently high flare values for 14 days. Intravitreal injection of interleukin (IL) 1, IL-6 and prostaglandin (PG) E(2) induced a significant increase in flare values. Following these treatments, introduction of a PG synthetase inhibitor can partially ameliorate BAB disruption. IL-1, IL-6 and PGE(2) may be involved in BAB disruption following retinal photocoagulation and cryopexy.

Differential transport of rat and human interleukin-1alpha across the blood-brain barrier and blood-testis barrier in rats

Human interleukin-1alpha is transported across the murine blood-brain barrier (BBB) and blood-testis barrier (BTB) by a saturable transport system. Differences in the biological activity and binding of human IL-1 in mouse and rat brain raise the possibility of species differences in the transport of IL-1 across the BBB and BTB. We measured the transport of recombinant human 125I-IL-1alpha (I-huIL-1alpha) and rat 125I-IL-1alpha (I-ratIL-1alpha) across the rat BBB and BTB after intravenous injection using a sensitive in vivo technique and film autoradiography. I-ratIL-1alpha was found to cross the rat BBB and rat BTB at rates comparable to those reported previously for murine IL-1alpha in mice. Passage across the BBB was inhibited by the addition of unlabeled rat IL-1alpha, demonstrating saturable transport. In contrast, I-huIL-1alpha entered the brain of the rat much more slowly, and its entry was not inhibited by the addition of unlabeled human IL-1alpha. These results show that the rat interleukin-1 transporter, unlike the murine transporter, does not transport human IL-1alpha. This difference highlights the importance of species specificity in IL-1alpha transport and may partly explain the different physiological responses to exogenous human IL-1alpha among rodent species.

Hemodiafiltration with online regeneration of the ultrafiltrate

The concept of regeneration of dialysis fluids and of ultrafiltrate in particular has been recently revisited. Hemodiafiltration with online regeneration of the ultrafiltrate allows the concomitant infusion of sodium, calcium, and bicarbonate. Here, we studied the adsorptive characteristics of an integrated two-step sorbent system relative to different solutes present in the ultrafiltrate: sodium, calcium, phosphate, bicarbonate, uric acid, creatinine, and beta2-microglobulin. In vitro studies were performed in order to differentiate the relative roles for each sorbent (mineral-activated charcoal or hydrophobic resin) in adsorbing a given solute. Ex vivo studies were performed in order to evaluate the presence of cytokines (interleukin-1 beta and tumor necrosis factor-alpha), of cytokine (interleukin-1 beta and tumor necrosis factor-alpha)-inducing activities, and of the cytokine release in response to exogenous bacterial lipopolysaccharide by normal whole blood incubated with ultrafiltrate samples obtained at 15, 120, and 240 minutes after the start of treatment. The results of the present studies show the presence of immunomodulatory substances in the ultrafiltrate and the significant (P < 0.01) increase in the lipopolysaccharide-induced release of both interleukin-1 beta and tumor necrosis factor-alpha. The biological relevance of the ultrafiltrate and the possible relevance of the online, endogenous reinfusion are discussed.

Glycosylated human interleukin-1alpha, neoglyco IL-1alpha, coupled with N-acetylneuraminic acid exhibits selective activities in vivo and altered tissue distribution

In order to study the effect of glycosylation on its biological activities and to develop IL-1 with less deleterious effects, N-acetylneuraminic acid (NeuAc) with C9 spacer was chemically coupled to human recombinant IL-1alpha. NeuAc-coupled IL-1alpha (NeuAc-IL-1alpha) exhibited reduced activities in vitro and receptor-binding affinities by about ten times compared to IL-1alpha. In this study, we examined a variety of IL-1 activities in vivo. NeuAc-IL-1alpha exhibited a marked reduction in the activity to up-regulate serum IL-6, moderate reduction in the activities to up-regulate serum amyloid A and NOx. However, it exhibited comparable activities as IL-1alpha to down-regulate serum glucose and to improve the recovery of peripheral white blood cells from myelosuppression in 5-fluorouracil-treated mice. In addition, tissue level of NeuAc-IL-1alpha was high compared to IL-1alpha. These results indicate that coupling with NeuAc enabled us to develop neo-IL-1 with selective activities in vivo and enhanced tissue level.

Intrarenal handling of recombinant human interleukin-1alpha in rats: mechanism for proximal tubular protein reabsorption

The intrarenal distribution of recombinant human interleukin (IL)-la was studied in Sprague-Dawley male rats by immunohistochemical staining. The effects of the concurrent administration of various proteins or synthetic polypeptides on the urinary excretion of IL-1alpha were also studied to clarify the mechanism(s) for the reabsorption of IL-la in the renal tubules. Microscopic immunohistochemistry showed that IL-1alpha distributed to early proximal convoluted tubules but not to glomeruli, Henle's loops, distal tubules, or collecting ducts. Electron microscopic immunohistochemistry showed that IL-la was taken up into the endocytic vesicle located close to the apical membrane of the proximal tubular epithelial cells, then accumulated in lysosomes. Urinary excretion of intravenous IL-la at 500 microg/kg was extremely low, accounting for only 0.014% of the dose administered. The coadministration of intravenous human serum albumin did not affect the urinary excretion of IL-1alpha, whereas trypsinogen, myoglobin, and trypsin inhibitor dose-dependently produced an increase in the excretion of IL-la, the potency of which was greatest in that order. Poly-L-lysine, but not poly-L-glutamic acid dose-dependently increased the urinary excretion of IL-1alpha. These results indicate that most of the glomerular filtrated IL-1alpha could be easily reabsorbed into the proximal tubular cells via endocytosis, and the reabsorption was inhibited by coadministered low molecular weight proteins, particularly basic proteins. This result suggests that scavengers with a negative charge and broad binding ability for glomerular filtered proteins exist on the surface of the apical membrane of proximal tubular cells and play an important role in the reabsorption of filtered proteins.

Peripheral effects of centrally administered interleukin-1beta in mice in relation to its clearance from the brain into the blood and tissue distribution

Administration of interleukin IL-1 induces acute-phase response and inhibition of gastric secretion more efficiently when administered intracerebroventricularly (i.c.v.) than when the same dose of IL-1 is administered systemically. In this study we describe the pharmacokinetics of IL-1beta, administered centrally or systemically, in the serum or in peripheral tissues. IL-1beta administered i.c.v. resulted in higher peak IL-1beta concentrations, and lasted longer, than intravenous (i.v.) or intraperitoneal (i.p.) administration. Higher IL-1beta levels in the liver and heart were observed after i. c.v. administration (compared to the i.p. or i.v. route). Our data suggest that centrally injected IL-1 induces higher circulating and hepatic IL-1 levels and contributes to the fact that the i.c.v. route of administration is particularly effective in inducing a liver acute-phase response.

Tumor necrosis factor-alpha and interleukin-1beta synergistically depress human myocardial function

OBJECTIVE

Proinflammatory cytokines such as tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta have been implicated in the pathogenesis of myocardial dysfunction in ischemia-reperfusion injury, sepsis, chronic heart failure, viral myocarditis, and cardiac allograft rejection. Although circulating TNF-alpha and IL-1beta are both often elevated in septic shock, it remains unknown whether TNF-alpha or IL-1beta are the factors induced during sepsis that directly depress human myocardial function, and if so, whether the combination synergistically depresses myocardial function. Furthermore, the mechanism(s) by which these cytokines induce human myocardial depression remain unknown. We hypothesized the following: a) TNF-alpha and IL-1beta directly depress human myocardial function; b) together, TNF-alpha and IL-1beta act synergistically to depress human myocardial function; and c) inhibition of ceramidase or nitric oxide synthase attenuates myocardial depression induced by TNF-alpha or IL-1beta by limiting proximal cytokine signaling or production of myocardial nitric oxide (NO).

DESIGN

Prospective, randomized, controlled study.

SETTING

Experimental laboratory in a university hospital.

SUBJECTS

Freshly obtained human myocardial trabeculae.

INTERVENTIONS

Human atrial trabeculae were obtained at the time of cardiac surgery, suspended in organ baths, and field simulated at 1 Hz, and the developed force was recorded. After a 90-min equilibration, TNF-alpha (1.25, 12.5, 125, or 250 pg/mL for 20 mins), IL-1beta (6.25, 12.5, 50, or 200 pg/mL for 20 mins), or TNF-alpha (1.25 pg/mL) plus IL-1beta (6.25 pg/mL) were added to the bath, and function was measured for the subsequent 100 mins after the 20-min exposure. To assess the roles of the sphingomyelin and NO pathways in TNF-alpha and IL-1beta cross-signaling, the ceramidase inhibitor N-oleoyl ethanolamine (1 microM) or the NO synthase inhibitor N(G)-monomethyl-L-arginine (10 microM) was added before TNF-alpha (125 pg/mL) or IL-1beta (50 pg/mL).

MEASUREMENTS AND MAIN RESULTS

TNF-alpha and IL-1beta each depressed human myocardial function in a dose-dependent fashion (maximally depressing to 16.2 + 1.9% baseline developed force for TNF-alpha and 25.7 + 6.3% baseline developed force for IL-1beta), affecting systolic relatively more than diastolic performance (each p < .05). However, when combined, TNF-alpha and IL-1beta at concentrations that did not individually result in depression (p > .05 vs. control) resulted in contractile depression (p < .05 vs. control). Inhibition of myocardial sphingosine or NO release abolished the myocardial depressive effects of either TNF-alpha or IL-1beta.

CONCLUSIONS

TNF-alpha and IL-1beta separately and synergistically depress human myocardial function. Sphingosine likely participates in the TNF-alpha and IL-1beta signal leading to human myocardial functional depression. Therapeutic strategies to reduce production or signaling of either TNF-alpha or IL-1beta may limit myocardial dysfunction in sepsis.

Lixelle adsorbent to remove inflammatory cytokines

A beta2-microglobulin (beta2M) selective adsorbent (Lixelle) for direct hemoperfusion has been used for the treatment of hemodialysis patients with the long-term complication of dialysis related amyloidosis (DRA), but there is no significant correlation between the serum level of beta2M and the occurrence of DRA. Inflammatory cytokines such as interleukin (IL)-1, IL-6, and tumor necrosis factor alpha (TNFalpha) are related to the development of DRA. We studied the adsorptive rates of cytokines in vitro using the Lixelle adsorbent. The adsorptive rates were 98.5% for IL-1beta 98.0% for interleukin-1 receptor antagonist (IL-1RA), 82.9% for IL-6, 99.9% for IL-8, 31.2% for TNFalpha, and 46.1% for soluble TNF receptor (sTNFr), respectively. As the molecular weights of cytokines increase, the adsorptive rates decrease. The Lixelle column adsorbed beta2M and various inflammatory cytokines as well. Therefore, the removal of both beta2M and inflammatory cytokines may play an important role in the treatment of DRA.

Effect of IL-1alpha on the release of norepinephrine in rat hypothalamus

The increased release of norepinephrine (NE) in the brain as part of the 'acute phase response' has been postulated to result from a direct action of IL-1 on the hypothalamus. To test whether the effects of IL-1alpha were direct, we carried out in vivo experiments using microdialysis and measured NE release in the hypothalamus using high pressure liquid chromatography (HPLC). Two groups of male Sprague Dawley rats were either injected intraperitoneally with 1 ml of IL-1alpha (2 microg/ml) or had IL-1alpha 2 microl (100 ng/ml) infused directly into the medial hypothalamus. A significant increase in extracellular hypothalamic NE was observed in the animal group treated with IL-1alpha intraperitoneally and not in the controls or the group treated with IL-1alpha intracerebrally. One-way ANOVA showed a significant effect of drug and route of administration with the ip IL-1alpha treated group, differing from all other groups (vehicle ip, IL-1alpha ic, and vehicle ic). Therefore these findings suggest that some aspects of IL-1alpha actions on the HPA may be indirect requiring other intermediate steps or mediators outside the central nervous system.

Interleukin 1 (IL-1) type I receptors mediate activation of rat hypothalamus-pituitary-adrenal axis and interleukin 6 production as shown by receptor type selective deletion mutants of IL-1beta

The cytokine interleukin 1 (IL-1) plays an important role in the activation of the hypothalamus-pituary-adrenal (HPA)-axis and interleukin 6 (IL-6) production during infection or inflammation. Which of the interleukin-1 receptor types mediates these effects is not known. To investigate this issue a pharmacological approach was chosen by using recently developed IL-1 receptor type selective ligands. Rats were given one of various doses of recombinant human IL-1beta (rhIL-1beta; 1 and 10 microg/kg) and of several IL-1beta mutants (DeltaSND, DeltaQGE and DeltaI; 1, 10 and 100 microg/kg), that differ in their affinities for the IL-1 type I receptor but have similar affinities for the IL-1 type II receptor. One hour after intravenous administration of rhIL-1beta or IL-1beta mutants, plasma levels of ACTH, corticosterone (cort) and IL-6 were measured. Doses of 1 and 10 microg/kg rhIL-1beta markedly elevated plasma levels of ACTH, cort and IL-6. However, 10-100-fold higher doses of IL-1beta mutants DeltaSND and DeltaQGE and at least 100-fold higher doses of DeltaI have to be administered to increase plasma levels of ACTH, cort and IL-6. The potency differences correlate with their respective affinity for the type I receptor but not with that of the IL-1 type II receptor. It is concluded that IL-1beta induced ACTH, cort and IL-6 production is mediated by interleukin 1 type I receptors.

Transfer of endogenous pyrogens across artificial membranes?

Synthetic high-flux dialyzer membranes used in continuous veno-venous hemofiltration are permeable to middle molecular size endogenous pyrogens, the pro-inflammatory cytokines IL-1 beta and TNF-alpha. The quantities removed by sieving are, however, negligible in vitro as well as in vivo. Adsorption of cytokines to the membrane polymer is the major mechanism of pyrogen removal. Adsorption seems to be semispecific for pro-inflammatory cytokines because levels of anti-inflammatory mediators were not changed or even increased during CVVH. Thus, CVVH may change cytokine profiles in septic patients supporting the predominance of anti-inflammatory over pro-inflammatory activity in plasma. It remains to be demonstrated whether modifications of extracorporeal blood purification systems (high-volume CVVH, plasma separation + adsorption) are able to amplify the change in cytokine profiles and whether this change influences outcome of septic patients.

In vivo expression of interleukin-1 receptors during various experimentally induced inflammatory conditions

Systemically administered interleukin-1 (IL-1) has been shown to preferentially bind to IL-1 receptors (IL-1Rs) in inflammation. Using radiolabeled IL-1alpha and molecular methods to assess gene expression for these receptors, the in vivo behavior of these receptors was investigated in a number of experimental inflammatory conditions. The uptake of 125I-labeled IL-1alpha in inflammatory foci significantly correlated with the mRNA expression for the type I and type II IL-1Rs (P < .05). Type II IL-1R mRNA showed a greater increase in expression than type I IL-1R mRNA. In neutropenic mice, inflammatory lesions, which are devoid of granulocytes, significantly lower 125I-labeled IL-1alpha uptake (P < .001), and type II IL-1R mRNA expression (P < .005) was found. Thus, there is strong up-regulation of IL-1Rs at sites of focal inflammation. Of interest, this mainly involved the type II IL-1R on granulocytes, which is not involved in signal transduction.

Interleukin-1 beta induced transient diabetes mellitus in rats. A model of the initial events in the pathogenesis of insulin-dependent diabetes mellitus?

When aiming at preventing IDDM in man, knowledge of the molecular mechanisms leading to beta cell destruction may facilitate identification of new possible intervention modalities. A model of IDDM pathogenesis in man suggests that cytokines, and IL-1 in particular, are of major importance in the initial events (Nerup et al 1994) (Fig. 1). In vitro rat experiments demonstrated that rhIL-1 beta inhibits beta cell function and induces beta cell death both in isolated islets of Langerhans and in the isolated perfused pancreatic gland. With the long term goal of identifying new modalities capable of preventing IDDM in man, the aim af this review was to investigate the effects of rhIL-1 beta on beta-cell function and viability in normal rats. This review discussed 1) the pharmacokinetics of IL-1 beta in rats as the basis for choice of route of administration and dose of rhIL-1 beta, 2) the effects and molecular mechanisms of IL-1 beta on temperature and food intake used as control parameters for successful injection of rhIL-1 beta in rats, 3) the effects of one or more injection of IL-1 beta on rat beta cell function, 4) the molecular mechanisms leading to IL-1 beta induced beta cell inhibition in vivo, and some possible intervention modalities based on the molecular mechanisms, 5) the effects of IL-1 beta on spontaneous diabetes mellitus in DP BB rats, and 6) the effects and molecular mechanisms of IL-1 beta induced inhibition of thyroid epithelial cell function and aggravated thyroiditis in DP BB rats, compared to the effects of IL-1 beta on rat beta cell function. Finally, this review discussed the effects of IL-1 beta on human beta cells in vitro, and the clinical relevance of these experiments, with special reference to a clinical trial with the aim of preventing IDDM in man. The pharmacokinetic studies suggested that IL-1 beta is distributed according to a two-compartment model with a first-order elimination. Interleukin-1 beta reached all the investigated organs in the rats, was accumulated in kidneys and was excreted in the urine. The data suggested that IL-1 beta also accumulated in the islets of Langerhans. After injection of 4.0 micrograms/kg pathophysiologically relevant concentrations of rhIL-1 beta were reached and intact rhIL-1 beta persisted for up to 5 hrs in plasma. Peripheral injections of IL-1 beta dose-dependently induced fever and anorexia in rats, probably via induction of PGE2 in the brain or in peripheral tissues thereafter passing the blood-brain barrier. Nitric oxide produced by cNOS seems to be a molecular mediator of IL-1 beta induced fever but not of anorexia. Fever and anorexia are well described effects of IL-1 beta in rats, and are as such usefull control parameters of the absorption and biological activity of IL-1 beta after peripheral injection. Injections of rhIL-1 beta to normal, non-diabetes prone rats induced initial beta cell stimulation followed by inhibition, in accordance with in vitro data. Furthermore, induction of peripheral insulin resistance coincided with beta cell inhibition after one daily injection for 5 days, leading to a transient diabetes mellitus-like state, characterized by hyperglycemia and hypoinsulinemia. At this time point, electron-microscopy did not demonstrate beta cell destruction. However, IL-1 beta induced intercellularly edema and microvillous processes on the beta cells, which might be early evidence of apoptosis. The diabetes mellitus-like state was not aggravated if the daily injections were continued beyond 5 days. Daily injections of rhIL-1 beta for 2 to 4 weeks induced formation of blocking IL-1 beta-antibodies in normal rats. Hence, injections exceeding 2 weeks should only be performed using species homologous IL-1 beta. The molecular mechanism of IL-1 beta induced beta cell inhibition in rats in vivo as in vitro, are likely to involve binding of IL-1 beta to the IL-1RtI, since the IL-1RtII is considered to be a decoy receptor. (ABSTRACT TRUNCATED)

Preferential localization of systemically administered radiolabeled interleukin 1alpha in experimental inflammation in mice by binding to the type II receptor

Previously, we have shown that systemically administered radiolabeled interleukin 1alpha (IL-1alpha) accumulates preferentially in inflammatory foci in mice. Since inflammation is characterized by influx of leukocytes, which represent IL-1 receptor (IL-1R) positive cells, radiolabeled IL-1 may specifically localize in inflammation by binding to its receptors on infiltrated leukocytes. This hypothesis was tested in a series of studies in mice with acute focal inflammations. Evidence for specific IL-1-IL-1R interaction in induced inflammation was found: microscopic autoradiography revealed that 125I-IL-1alpha localized at the site of inflammatory cells with time; 125I-myoglobin, a similar-sized protein with no known interactions in vivo, was not retained in the inflammation. Furthermore, the uptake 125I-IL-1alpha in inflammatory tissue was significantly lower in neutropenic mice than in immunocompetent mice (0.05+/-0.004 vs. 0.65+/-0.06% ID/g at 48 h after injection, P < 0.0007). Moreover, the uptake of 125I-IL-1alpha at the inflammatory site could be blocked with the anti-IL-1R type II antibody 4E2. At 48 h after injection, the uptake with and without blocking the type II IL-1R was 0.13+/-0.01 and 0. 65+/-0.05% ID/g, respectively (P < 0.0001). These in vivo studies provide evidence that systemically administered radiolabeled IL-1alpha localizes in inflammatory tissue by specific receptor binding, predominantly by binding to the type II IL-1R.

Relative contributions of peripheral and central sources to levels of IL-1 alpha in the cerebral cortex of mice: assessment with species-specific enzyme immunoassays

The peripheral administration or release of cytokines is associated with central nervous system (CNS) effects that are often due to the actions of cytokines behind the blood-brain barrier (BBB). It is not known whether the majority of cytokine behind the BBB is derived from blood or is released from the CNS in response to peripheral signals. We addressed this question for interleukin-1 alpha (IL-1 alpha) by infusing human IL-1 alpha (humIL-1 alpha) into mice and measuring humIL-1 alpha and murine IL-1 alpha (murIL-1 alpha) in cerebral cortex and serum with specific, sensitive enzyme immunoassays. In adult mice receiving 50 micrograms/kg-24 h of humIL-1 alpha subcutaneously for 48 h, brain and blood samples contained humIL-1 alpha but no murIL-1 alpha. This shows that in our study blood-borne IL-1 alpha did not self-stimulate its release in blood or brain. The presence of humIL-1 alpha in brain could only have originated from blood, where it was administered; the brain/blood ratio of 0.126 ml/g indicates that at steady state, brain levels reach about 12% of blood levels. In neonatal mice, both murIL-1 alpha and humIL-1 alpha were detected in brain and blood after the acute subcutaneous injection of humIL-1 alpha. However, the vast majority of immunoactivity in blood and brain was humIL-1 alpha. These results show that most of the IL-1 alpha appearing in response to circulating IL-1 alpha in areas of the CNS behind the BBB is due to passage across the BBB and not to release from stores endogenous to the CNS.

Penetration of keratinocyte-derived cytokines into basement membrane

Keratinocytes are known to produce a wide variety of cytokines which are believed to play a significant role in cutaneous inflammatory and immunologic reactions. Considering the array of proteolytic enzymes present in the skin and the transient nature of cytokines produced from keratinocytes, it is unclear whether cytokines released by keratinocytes cross the basement membrane and contribute to distal inflammatory and immune reactions. To investigate the ability of cytokines released from human keratinocytes to cross basement membrane, we used a two chamber culture model. Keratinocytes were plated in the upper chamber coated with a reconstituted basement membrane matrix (matrigel) on a microporous membrane. To augment cytokine production, we exposed keratinocytes to 300 J/m2 UVB; 24 h later the supernatants were collected, and the levels of cytokine were measured by ELISA. IL-1alpha, IL-6, and TNF-alpha were found to be increased after UVB irradiation in the upper chamber, and significant amounts (70-80%) of each cytokine were detected in the lower chamber. Our results indicate that keratinocyte-derived cytokines are available for interactions below the basement membrane and present circumstantial evidence that the production of those cytokines from keratinocytes contributes to the elevation of circulation after the UVB exposure.

Different behaviour of radioiodinated human recombinant interleukin-1 and its receptor antagonist in an animal model of infection

Recently, we demonstrated that radiolabelled interleukin-1alpha (IL-1) specifically accumulates in focal infection in mice through interaction with its receptor. Unfortunately, systemic side-effects of IL-1 limit its clinical application. We investigated whether this problem could be circumvented by using the interleukin-1 receptor antagonist (IL-1ra), an equally sized protein that binds to the same receptors as IL-1 without induction of biological effects. Biodistribution of 125I-IL-1 and 125I-IL-1ra was determined in Swiss mice with Staphylococcus aureus-induced abscesses in the left calf muscle at 4, 12, 24 and 48 h after injection of either 0.4 MBq 125I-IL-1 or 0.4 MBq 125I-IL-1ra. In vitro, the proteins displayed similar binding characteristics. High-performance liquid chromatographic analysis revealed a tendency for IL-1ra to associate with serum proteins. Both proteins rapidly cleared from most organs. However, the abscess uptake of 125I-IL-1ra was significantly lower than that of 125I-IL-1 at all time points (48 h p.i.: 0.06+/-0. 01%ID/g vs 0.60+/-0.04%ID/g; P<0.02). The abscess-to-contralateral muscle ratios did not exceed 15.5+/-2.9 for 125I-IL-1ra, while the ratios for 125I-IL-1 reached 46.9+/-5.7 at 48 h p.i. Despite similar in vitro receptor binding, the abscess uptake of IL-1ra was much lower than that of IL-1. The interaction of IL-1ra with serum proteins in vivo may reduce its availability for receptor binding in the infection. Although on theoretical grounds IL-1ra is very interesting, these characteristics will prevent its development as a clinically useful radiopharmaceutical to image infection.

Interleukin-1 but not tumour necrosis factor alpha synergistically upregulates the granulocyte-macrophage colony-stimulating factor-induced B7-1 expression of murine Langerhans cells

Epidermal Langerhans cells (LC) express several co-stimulatory molecules such as B7/BB1, which has been implicated as one of the important determinants for potent antigen-presenting function of LC. Recent studies have shown that B7/BB1 antigens comprise three distinct molecules termed B7-1, B7-2 and B7-3. Previous studies have revealed that the phenotypic and functional properties of murine LC are enormously affected by various cytokines including granulocyte-macrophage colony stimulating factor (GM-CSF), interleukin-1 (IL-1), and tumour necrosis factor alpha (TNF-alpha) derived from surrounding keratinocytes. We have already demonstrated that the expression of B7-1 of murine LC is significantly enhanced by GM-CSF, IL-1 or TNF-alpha. In this paper, we present that IL-1, but not TNF-alpha, synergistically up-regulates the GM-CSF-induced B7-1 expression of murine LC.

D-mannose dimer introduced human recombinant interleukin- 1 alpha, NEO IL-1 alpha, exhibits altered tissue distribution in mice

Previous studies have demonstrated that the carbohydrate-introduced recombinant human IL-l alpha exhibited impairment in both biologic activities in all the experiments in vitro and receptor binding capacity compared with intact IL-l alpha. However, the glycosylated IL-l alpha exhibited selective activities in vivo. In this study, we compared the tissue distribution of IL-l alpha and IL-l alpha coupled with D-Mana (l-6)Man [Man2 alpha) (l-6)IL-l alpha] in mice. Mice were injected by intravenous and intraperitoneal routes with 2.0 mu g radiolabeled IL-l alpha. At 1 and 2 h after IP injection, the level of Man2 alpha) (l-6)IL-l alpha decreased twofold compared with that of IL-l alpha in kidney. In contrast, at 1 hour after administration, Man2 alpha) (l-6)IL-l alpha exhibited higher levels than IL-l alpha in blood, heart, and liver. No significant difference was observed in brain at each time point. IV injection demonstrated that Man2 alpha)(l-6)IL-l alpha decreased to approximately one-half the level of rhIL-l alpha in kidney. In contrast, Man(2 alpha) (l-6)IL-l alpha increased twofold over that of IL-l alpha in liver at 1 h after dosing. These findings are consistent with the result of IP injection. There was no significant difference between IL-l alpha and glycosylated IL-l alpha at 4 h after IV administration. These differences in tissue distribution may contribute to the selective activities of glycosylated IL-l alpha in vivo. The results also suggest that by coupling with mannose dimer, it is possible to develop neocytokines prone to liver distribution.

Induction of interleukin 1 receptor antagonist after interleukin 1 therapy in patients with cancer

The interleukin 1 receptor antagonist (IL-1ra) is a naturally occurring molecule that shares homology with IL-1alpha and IL-1beta and binds competitively to IL-1 receptors. Serum concentrations of IL-1ra were measured by ELISA in patients enrolled in Phase I clinical trials of IL-1alpha and IL-1beta given by 15-min infusion. Pretreatment levels of IL-1ra were <1500 (mean, 453 +/- 57) pg/ml. IL-1ra levels were increased in some patients within 1 h of completing the IL-1 infusion. By 2 h after infusion, serum levels of IL-1ra had increased dramatically, and they remained stable 4 h after infusion. There was evidence that peak IL-1ra levels were IL-1 dose dependent. Seven patients treated with IL-1alpha had IL-1ra levels that exceeded 1 microgram/ml. In contrast, serum levels of IL-1 declined rapidly and were undetectable 1 h after completing IL-1 infusion in most patients receiving <1.0 microgram/kg. IL-1ra levels remained slightly elevated over pretreatment values in serum obtained 18-24 h after IL-1 infusion, but there was no evidence for progressive accumulation over repeated days of therapy. A similar pattern of IL-1ra elevation was observed after the last IL-1 infusion on day 6. This study shows that cancer patients produce 2 to >6 log incremental increases in IL-1ra rapidly following treatment with IL-1, a response that has implications for the design of future clinical trials with IL-1 and with agents thought to induce IL-1 production.

Anti-inflammatory and analgesic activities of 3-imino-1-oxoisoindolines in CF1 mice

A series of 3-imino-1-oxoisoindolines were shown to be potent anti-inflammatory and analgesic agents at 8 mg/kg, intraperitoneally in mice. The compounds were also able to protect against lipopolysaccharide induced endotoxic shock and death better than the current clinical agents. These agents appear to function by blocking the release of TNF alpha and IL-1 from macrophages as well as competition with their respective high affinity receptors on target tissue, eg. fibroblasts, and macrophages. In addition lysosomal hydrolytic enzymes were inhibited as well as leukotriene synthesis in macrophages by the agents.

Selective transport of blood-borne interleukin-1 alpha into the posterior division of the septum of the mouse brain

Film autoradiography was used to demonstrate the transport and sites of accumulation of blood-borne radioiodinated interleukin-1 alpha (II-1 alpha) and other cytokines into the brain after intravenous administration. [125 I]Il-1 alpha, [125I]Il-1 beta, [125I]interleukin-1 receptor antagonist (II-1ra), and [125I]tumor necrosis factor-alpha (TNF alpha) labeled the choroid plexus and the capillary network 30 min after injection into the blood, suggesting that these areas may serve as sites of blood-to-brain transport. [125I]Il-1alpha, but not [125I]Il-1beta, [125I]Il-1ra, [125I]TNF alpha, or [125I]interleukin-2 (Il-2), was also found localized to the caudal region of the septal nuclei. Only unlabeled II-1 alpha was able to inhibit this accumulation. These findings provide further evidence for the passage of select cytokines across the blood-brain barrier (BBB) and are the first to identify a target site within the central nervous system (CNS) for a transported cytokine.

Specific targeting of infectious foci with radioiodinated human recombinant interleukin-1 in an experimental model

In the present study, radioiodinated human recombinant interleukin-1 (IL-1) was investigated for its potential to image infectious foci in vivo in an animal model of infection. Twenty-four hours after induction of a Staphylococcus aureus abscess in the left calf muscle, mice were i.v. injected with both iodine-125 labelled IL-1 and iodine-131 labelled myoglobin, a size-matched control agent. The animals were killed for tissue biodistribution studies at 2, 6, 12, 24 and 48 h p.i. Gamma camera images were obtained at 6, 24 and 48 h after injecting mice with 123I-IL-1. Radioiodinated IL-1 rapidly cleared from the body; after 12 h the abscess was the organ with the highest activity. The absolute abscess uptake of 125I-IL-1 remained high compared to 131I-myoglobin, resulting in significantly higher abscess-to-muscle ratios of 125I-IL-1 compared to 131I-myoglobin. The ratios of 125I-IL-1 reached the ultimate value of 44.4+/-10.8 at 48 h p.i., whereas the ratios of 131I-myoglobin did not exceed 5.9+/-0.7. Gamma camera imaging revealed clearly visible abscesses. In conclusion, our results demonstrate specific retention of radioiodinated IL-1 in the abscess, presumably by interaction of IL-1 with its receptor on the inflammatory cells. The high target-to-background ratios that were obtained over the course of time indicate that the IL-1 receptor may be a valuable target for the imaging of infectious foci.

Permeability of the blood-brain barrier to soluble cytokine receptors

Soluble receptors for cytokines can be important regulators of cytokine function. By binding to their cytokine ligands, they act as antagonists and carrier proteins. We investigated whether the blood-to-brain saturable transport of human tumor necrosis factor-alpha (TNF) and human interleukin-1 alpha (IL-1) radioactively labeled with 125I could be blocked by preincubation with their soluble receptors. At ratios of 100:1 and 1,000:1 of receptor to cytokine, the soluble p75 human receptor to TNF (rhuTNFR:Fc) totally blocked the entry of human or murine TNF into the brain. However, the soluble murine receptor to IL-1 (muIL-1R) only partially blocked IL-1 entry. Radioactively labeled rhuTNFR:Fc and muIL-1R were not transported across the blood-brain barrier (BBB) and were no more able to penetrate the BBB than the vascular marker serum albumin. This indicates that the transporter at the BBB for IL-1, but not the one for TNF, can strip the cytokine from its soluble receptor. These findings might be useful in determining which, if any, of the actions exerted on the brain by blood-borne cytokines are due to penetration of the BBB.

Possible role of cytokines in cellular proliferation of the skin transplanted onto nude mice

BACKGROUND AND DESIGN

In recent studies on the behavior of aged skin transplanted onto nude mice, the epidermis of aged and young skin showed an increase in proliferation and thickness following engraftment, and became almost identical. The aim of this study was to ascertain a possible role for the release of local cytokines in this phenomenon. Grafted human skin was injected intradermally with anti-interleukin-6 (IL) and anti-IL-1 alpha, and comparisons of epidermal thymidine incorporation and thickness were made. Grafts injected with irrelevant antibodies served as control.

RESULTS

Interleukin-6 and IL-1 alpha expression were studied in grafts by immunoperoxidase staining. Only IL-6 expression was found in the 1-month grafts. Intradermal injections of anti-IL-1 alpha and anti-IL-6 showed an inhibitory effect on cellular proliferation in the epidermis. A significant difference in the response of epidermal proliferation and, consequently, in thickness was found in samples injected with anti-IL-1 alpha and anti-IL-6 compared with those injected with irrelevant antibodies.

CONCLUSIONS

These data may indicate that local cytokines released by the keratinocytes are involved in the cellular proliferative activity in skin engrafted onto the mice.

Blood-borne interleukin-1 alpha is transported across the endothelial blood-spinal cord barrier of mice

1. Previous work has shown that one mechanism by which blood-borne interleukin-1 alpha (IL-1) may be able to affect the central nervous system (CNS) is by direct transport into the brain across the blood-brain barrier (BBB). The BBB of the brain consists of endothelial (between blood and interstitial fluid) and ependymal (between blood and cerebrospinal fluid) barriers. Which of these barriers IL-1 can cross has not previously been investigated. At the spinal cord, which could be the site of action for some of the effects of IL-1 such as analgesia, the BBB consists only of the endothelial barrier. 2. We show here that IL-1 labelled with 125I (I-IL) is transported across the BBB of the spinal cord by a saturable system similar to the one previously described for the brain. High performance liquid chromatography (HPLC) showed that most of the material entering the spinal cord represented intact I-IL. The BBB of the spinal cord was no more leaky to radioactively labelled albumin than the BBB of the brain and was not disrupted by 50 micrograms kg-1 of IL-1. 3. Capillary depletion showed that most of the I-IL entered the parenchymal-interstitial fluid space of the spinal cord with only a modest amount being sequestered by the endothelial cells of its BBB. 4. I-IL entered the cervical, thoracic and lumbar regions of the spinal cord equally well. I-IL entering at the brain and diffusing caudally was estimated only to account for about 1% of the total radioactivity found in the spinal cord after i.v. injection.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin-1 beta (IL-1 beta) binds to intact porcine thyroid follicles, decreases iodide uptake but has no effect on cAMP formation or proliferation

Interleukin-1 beta (IL-1 beta) is known to be involved in autoimmune thyroiditis. Since the results of different in vitro-studies on the effect of IL-1 on thyrocytes are controversial, our aim was to investigate the existence of specific binding sites for IL-1 beta and its influence on specific functions and growth of isolated porcine thyroid follicles ex vivo with a preserved iodide metabolism. For binding studies isolated thyroid follicles were incubated with 125I-IL-1 beta (213.5 nCi/ml) and with increasing concentrations of unlabelled IL-1 beta (0.06-11.5 nmol/l) for 24 h at 4 degrees C. The dissociation constant Kd was 0.85 x 10(-10) mol/l and about 800 binding sites per cell were calculated. IL-1 beta (10 U/ml) decreased basal and TSH-stimulated iodide uptake and organification after an incubation time of 45 min to 6 h without any influence on cAMP-formation. In addition, after 40 h of incubation IL-1 beta dose-dependently increased T3-secretion, followed by a decrease during simultaneous TSH-stimulation, whereas there was no effect on T4-secretion. In contrast to these functional effects IL-1 beta showed no influence on the growth of thyroid follicles, so that the cytokine cannot be made responsible for goiter growth in thyroid diseases by directly influencing thyroxytes.

Induction, transcription, synthesis, and adsorption of interleukin-1 by dialyzer membranes

This study was designed to dissect the direct effect of dialyzer membrane on interleukin-1 (IL-1) induction from those of complement activation, mechanical stimulation, acetate/bicarbonate and endotoxin diffusion, and cell type interactions. To this end, a suspension of P388D1 murine macrophages in a complement-free culture medium containing 10% heat-inactivated serum, a closed-loop system consisting of tubing alone or with a hollow-fiber cuprammonium cellulose (CU) or polyacrylonitrile (PAN) dialyzer, and a roller pump were used. The dialysate compartment was filled with the same medium and capped. Cell suspension was recirculated at 300 mL/min for 3 h. Cells and supernates were separated, and adhering proteins were eluted. All samples tested negative for endotoxin. IL-1 mRNA was greatest with CU, followed by PAN and tubing alone. IL-1 in the supernate was greater with CU than with either tubing alone or PAN (P < 0.005; analysis of variance), which showed comparable values. IL-1 eluted from loops was greatest with PAN dialyzers, followed by sets with CU dialyzers and tubing alone (P < 0.001; analysis of variance). Thus, both CU and PAN membranes directly induce IL-1. However, avid adsorption by PAN attenuates the rise in circulating IL-1.

Quantification of recombinant human interleukin-1 alpha by a specific two cell immunobioassay

The detection of picogram quantities of recombinant human IL-1 alpha in human and rat serum was accomplished by a sensitive and specific two cell immunobioassay. The specificity is provided by an IL-1 alpha specific mouse IgM monoclonal antibody which is non-neutralizing thus allowing for the addition of the EL-4 NOB-1 cell line directly to the IL-1 alpha monoclonal antibody complex. The above cell line is then converted to an IL-2 producer line in response to the captured IL-1 alpha. Supernatant from the EL-4 NOB-1 cells is then added to the IL-2 dependent CTLL-2 line and cell proliferation measured by thymidine incorporation. This assay has the advantage of specificity provided by the antibody capture step, sensitivity provided by the EL-4 NOB-1 line (1-50 pg/ml) and finally ease of maintenance of the responder cell line which requires no feeder cells or mitogens. Data are reported on the sensitivity, precision, reproducibility and specificity of the assay, the stability of rhIL-1 alpha in serum and the recovery of rhIL-1 alpha from serum. We also report on the use of this procedure to assay samples from rats given ascending doses of rhIL-1 alpha.

Transfer of cytokines through human fetal membranes

Intact human fetal membranes (amnion, chorion and decidua) were incubated with 125I-labelled cytokines added to the fetal or maternal sides of the membrane. The transfer of 125I-labelled interleukin-6 (IL-6), 125I-labelled tumour necrosis factor alpha (TNF-alpha), 125I-labelled interleukin-1 alpha (IL-1 alpha) and 125I-labelled interleukin-1 beta (IL-1 beta) was determined by measurement of radioactivity in a gamma counter and the integrity of the cytokines was assessed by acid precipitation and by radioimmunoassay. IL-1 alpha and IL-1 beta were transferred through human fetal membranes in both feto-maternal and materno-fetal directions at similar rates. Only 2-4% of the cytokine originally added appeared to be intact on the opposing side of the membrane after 24 h of culture. Transfer of intact TNF-alpha (5-7%) and IL-6 (8-17%) was greater than that of the IL-1 isomers. Low but variable amounts of the four cytokines tested may be transferred through the human fetal membrane. This finding suggested that concentrations of cytokines in amniotic fluid would not reflect those produced by decidua if the fetal membranes are intact.

ELISA determination and preliminary pharmacokinetics of modified human rIL-1 beta in dogs

A single dose pharmacokinetic study with modified human Interleukin-1 Beta (IL-1 beta or DuP 118) was performed by injecting 5 micrograms/kg of drug into the jugular vein of three beagle dogs. Serial 5-ml plasma samples were removed from the dogs over a 120-minute period. DuP 118 plasma levels were measured using a sandwich ELISA technique capable of measuring concentrations ranging from 0.25 to 2 ng/ml with accuracy and precision constraints of less than +/- 20% variability. DuP 118 stored at -20 degrees C in dog plasma was stable for at least 1 month. Pharmacokinetic parameters were determined for the three dogs by standard model independent or non-compartmental methods. DuP 118 was rapidly distributed in the dog. The volume of distribution was approximately two-fold higher than the total body water of a lean dog. The terminal half-life was short, less than 30 minutes. Within approximately an hour after dosing, DuP 118 plasma levels were reduced 20-fold and were below the quantifiable limit of the assay.

Synergistic antiproliferative effects of interleukin-1 alpha and doxorubicin against the human ovarian carcinoma cell line (NIH:OVCAR-3)

Interleukin-1 alpha (IL-1 alpha) exerts antiproliferative effects on a human ovarian carcinoma cell line, NIH:OVCAR-3, which is resistant to clinically relevant concentrations of doxorubicin (DOX) and other chemotherapeutic agents. This action of IL-1 alpha depends on the presence of type I (80 kDa) receptors, although no quantitative relationship has been established between receptor occupancy and inhibition of cell growth. When NIH:OVCAR-3 cells were exposed to IL-1 alpha and DOX in combination, a mutual potentiation of the antiproliferative effects of the two agents was observed. This synergistic effect was not due to IL-1 receptor expression up-regulation by DOX, and receptor-dependent internalization of the cytokine was also unaffected. The involvement of IL-1 receptors is supported by the observation that synergism between the two agents was diminished (but not abolished) in the presence of a specific IL-1 receptor antagonist at concentrations blocking more than 75% of IL-1 alpha binding. DOX was found to significantly increase IL-1 alpha accumulation by NIH:OVCAR-3 cells after long-term (48 hr) exposure to the cytokine at 37 degrees, which might be due to increased nonspecific fluid phase uptake or to interference with cytokine degradation and/or release processes. The potent synergy of IL-1 alpha and DOX against ovarian carcinoma cells in vitro suggests that this drug combination may be effective against this disease in the clinic.

Adjuvant effect of interleukin-1 on the development of late asthmatic response in guinea pigs

The adjuvant effect of silica and IL-1 in the development of late asthmatic responses (LARs) in guinea pigs was studied. Different doses of silica or recombinant human (rh) IL-1 (1 microgram) with Ascaris suum were used for the immunization. The serum IL-1 concentration was measured after the immunization. One week after the immunization, antigen was challenged and respiratory resistance (Rrs) was measured. Rrs increased silica dose dependently in the late phase, and the increment of Rrs in the late phase was significantly correlated with the serum IL-1 concentration (p < 0.05). In addition, rhIL-1 administration showed an increase in Rrs at the late phase. Antigen-specific IgE and IgG1 were also measured and were increased in guinea pigs immunized both with silica and rhIL-1.

Human interleukin-1 alpha crosses the blood-testis barriers of the mouse

Interleukin-1 alpha (IL-1 alpha) has been shown to have direct effects on the gonads, affecting steroidal secretion, DNA synthesis by spermatogonia, and the immune function of the testes. It is unclear, however, how IL-1 alpha exerts these effects because the testis is partitioned into basal and adluminal compartments by both a vascular and a Sertoli cell barrier. The authors used a highly sensitive method to quantify the unidirectional flux rates (Ki) into the testis of technetium pertechnetate-labeled human albumin (T-alb), a compound that does not readily cross the vascular barrier, and human IL-1 alpha radioactively labeled with 125I (I-IL). The entry rate (Ki) was almost six times greater for I-IL than for T-alb. Part of the enhanced entry of I-IL was due to a saturable transport system. Nearly 0.2% of the total injection had entered the testes 60 minutes after intravenous administration, and more than 75% of that amount was not accounted for by the albumin space. Collection of testicular interstitial fluid from the basal compartment and seminiferous tubule fluid from the adluminal compartment showed preferential entry of I-IL into these compartments. Analysis by high-pressure liquid chromatography or radioactivity recovered from the testis showed that intact I-IL was entering the testis. The leakiness of the blood-testis barrier was measured by the rate of entry for T-alb, which was not altered by injection of unlabeled human IL-1 alpha in doses of up to 50 micrograms/kg (5 x 10(6) U/kg), and by the wet weight of the testes. The results show that circulating IL-1 alpha can have direct access to the testis, supporting previous studies suggesting a direct effect of IL-1 alpha on gonadal function.

Human interleukin (IL) 1 alpha, murine IL-1 alpha and murine IL-1 beta are transported from blood to brain in the mouse by a shared saturable mechanism

Interleukins (ILs) 1 alpha and 1 beta are important components of the neuroimmune axis. Recent work has shown that human 125I-IL-1 alpha can enter the brain from the blood by a saturable system, suggesting a mechanism that may directly link the immune and nervous systems. Here, it is shown that radioiodinated murine IL-1 beta and especially murine IL-1 alpha are even more rapidly transported into the brain of the mouse than is radioiodinated human IL-1 alpha after i.v. injection. All three cytokines exhibited self-inhibition, thus demonstrating saturable transport. Also, they all cross-inhibited the transport of each other. This shows that there are not three separate transport systems, but that they either share transport systems with overlapping affinities or share a single system. It was calculated that 0.06% to 0.08% of the dose of human 125I-IL-1 alpha injected i.v. was present in the brain during the first 60 min. By contrast, no saturable component could be detected in the brain to blood passage of the three ILs. No disruption of the blood-brain barrier to radioactively labeled albumin was found with i.v. doses of up to 50 micrograms/kg of human IL-1 alpha. Additional studies on the blood to brain transport of human 125I-IL-1 alpha showed no modification by dexamethasone, morphine, indomethacin or alpha-melanocyte stimulating hormone. Studies with antibodies directed toward the binding or nonbinding sites of IL or its receptor on the murine T lymphocyte suggest similar, but not identical, structural requirements for transport and for receptor binding.(ABSTRACT TRUNCATED AT 250 WORDS)

The pharmacokinetics, distribution and degradation of human recombinant interleukin 1 beta in normal rats

Based upon in vivo rat experiments it was recently suggested that interleukin 1 in the circulation may be implicated in the initial events of beta-cell destruction leading to insulin-dependent diabetes mellitus (IDDM) in humans. The aim of the present study was to estimate half-lives of distribution (T1/2 alpha) and elimination phases (T1/2 beta) of human recombinant interleukin 1 beta (rIL-1 beta), and its tissue distribution and cellular localization by means of mono-labelled, biologically active 125I-rIL-1 beta. After intravenous (i.v.) injection, 125I-rIL-1 beta was eliminated from the circulation with a T1/2 alpha of 2.9 min and a T1/2 beta of 41.1 min. The central and peripheral volume of distribution was 20.7 and 19.1 ml/rat, respectively, and the metabolic clearance rate was 16.9 ml/min/kg. The kidney and liver showed the highest accumulation of tracer, and autoradiography demonstrated that 125I-rIL-1 beta was localized to the proximal tubules in the kidney and to the hepatocytes in the liver. Furthermore, grains were localized to the islets of Langerhans in the pancreas. Tracer-bound proteins corresponding to intact 125I-rIL-1 beta were found in the circulation after i.v., intraperitoneal (i.p.) and subcutaneous (s.c.) injections, as demonstrated by high performance size exclusion chromatography, trichloracetic acid precipitation and SDS-PAGE until 5 h after tracer injection. Pre-treatment with 'cold' rIL-1 beta enhanced degradation of a subsequent injection of tracer. The route of administration was of importance for the biological effects of rIL-1 beta, as demonstrated by a reduced food intake, increased rectal temperature and blood glucose after s.c. injection of rIL-1 beta compared with i.p. The present demonstration of intact rIL-1 beta in the circulation and the islets of Langerhans supports the hypothesis that systemic IL-1 beta may be involved in the initial beta-cell destruction leading to IDDM in humans.

Repeated intraperitoneal injections of interleukin 1 beta induce glucose intolerance in normal rats

Previous in vitro findings suggest the involvement of interleukin 1 (IL-1) in the pathogenesis of insulin-dependent diabetes mellitus. The aims of the present study were to investigate the effects of single or repeated ip injections of recombinant IL-1 beta on blood glucose and glucose tolerance in vivo. Normal Wistar Kyoto rats were injected ip with a single injection of 4 micrograms/kg of the mature form of recombinant IL-1 beta (amino acids 117-269) or once daily on 5 consecutive days. Control rats were given vehicle and were fed ad libitum or pair-fed together with the rIL-1 beta treated rats. An ip glucose tolerance test (0.2 g D-glucose/100 g) was performed 2 h after injection of rIL-1 beta. A single injection of rIL-1 beta caused a mild depression in blood glucose and an improved glucose tolerance. Multiple injections of rIL-1 beta induced a diminished weight gain, a 24-28% reduction in food intake, a lasting mild depression of blood glucose (7 days) and a transiently impaired glucose tolerance on day 5. We conclude that systemic IL-1 should be considered an important regulator of glucose homeostasis in vivo.

Blood to brain transport of interleukin links the immune and central nervous systems

Interleukins (IL) are naturally occurring proteins that regulate, and thus link, both the immune system and the central nervous system (CNS). Since proteins are assumed not to be able to cross the blood-brain barrier (BBB), it is controversial how this linkage could occur. We show here that after iv injection of 125I-hIL-1 alpha, radioactivity in the brain eluted on HPLC in the position of the labeled cytokine. In addition, entry was inhibited by unlabeled hIL-1 alpha. Our demonstration of a saturable, carrier-mediated system that transports recombinant human IL-1 alpha in intact form from the blood into the CNS indicates a direct immune-CNS connection.

Cytokine administration alters the distribution of activated lymphocytes to the lung

The effects of intraperitoneal injections of recombinant interleukin-1 alpha (IL-1; 250,000 U/day), interleukin-2 (IL-2; 50,000 units/day), interferon-gamma (IFN-gamma; 50,000 U/day) and tumor necrosis factor-alpha (TNF; 100,000 U/day), on the biodistribution of concanavalin A (Con A)-activated, indium-111-labeled lymphocytes were evaluated in BALB/c mice. Syngeneic spleen cells were activated for 48 h in medium with Con A (5 micrograms/ml) and maintained in culture for 72 h in IL-2 (1,000 U/ml). Groups of 12 mice were treated for 4 days with either one of the cytokines or saline. On day 4, mice received 10(7) lymphocytes (3-5 mu Ci) intravenously. Mice were sacrificed at 4 and 24 h following injection and the percent of administered dose per organ was determined. TNF and IL-1 produced a significant increase in lung uptake of radiolabeled lymphocytes at 4 and 24 h, whereas IL-2 and IFN-gamma decreased uptake at both time points. IL-1 increased uptake by liver at 4 and 24 h while IL-2 increased uptake only at 4 h. We conclude that the distribution of activated lymphocytes following adoptive transfer is altered by cytokines. This finding may have important implications for cell delivery during adoptive immunotherapy.

Fate of injected interleukin 1 in rats: sequestration and degradation in the kidney

The tissue distribution and route of clearance of human recombinant interleukin 1 alpha (IL 1 alpha) injected intravenously in rats was studied. The plasma half-life was approximately 2.5 min, and this was increased after nephrectomy, the kidney being the major organ through which the IL 1 alpha was excreted. Two iodinated fragments of IL 1 alpha, of approximately 5 and 9 kDa, were excreted by the kidneys whereas only intact, 17-kDa IL 1 alpha was detected in plasma, suggesting that the protein was being degraded after uptake by the kidney. The results of in vivo experiments in which surface endopeptidase-24.11 was inhibited with phosphoramidon and in vitro experiments in which rat kidney homogenates were incubated with radiolabeled IL 1 alpha suggest that the cytokine was endocytosed and then hydrolysed by lysosomal proteinases.

The release of interleukin-1 beta, tumor necrosis factor-alpha and interferon-gamma by cultured peripheral blood mononuclear cells from patients with periodontitis

The extracellular release of IL-1 beta by cultured peripheral blood monocytes from 26 periodontitis patients and 26 control subjects was measured by radioimmunoassay. Unstimulated monocytes from periodontitis patients released significantly more IL-1 beta than controls during 24 h of culture; there was a wide variation in the amount of IL-1 beta released (0.45-13.00 ng/ml per 10(6) cells) which did not correlate with either the degree of bone loss or pocket formation observed clinically. When stimulated with lipopolysaccharide (LPS; Actinobacillus actinomycetemcomitans; 5 micrograms/ml) monocytes from periodontitis patients produced significantly more IL-1 beta than those from control subjects. Monocyte culture supernatants from another 10 periodontitis patients and 10 control subjects were also assayed for both IL-1 beta and TNF-alpha by enzyme-linked immunosorbent assays. Spontaneous and LPS-stimulated (Bacteroides gingivalis; 5 micrograms/ml) IL-1 beta release were again significantly higher for periodontitis patients. TNF-alpha was detected in the periodontitis cultures (0-765 pg/ml per 10(6) cells), but the mean value was not significantly different from controls. LPS-stimulated TNF-alpha release, however, was significantly higher than for control subjects, and there was a strong correlation between spontaneous IL-1 beta and TNF-alpha release by monocytes from the periodontitis group. Measurement of interferon-gamma (IFN-gamma) in lymphocyte cultures from these patients by immunoradiometric assay showed that IFN-gamma levels in periodontitis cultures were consistently low, but not significantly so when compared to controls; both groups responded equally to concanavalin-A (5 micrograms/ml). Although the precise roles of IL-1 beta and TNF-alpha in periodontitis remain unclear, these data provide evidence that both cytokines may participate in the pathogenesis of the disease.

Interleukin-1 beta but not interleukin-1 alpha, induces acute inflammation-like changes in the testicular microcirculation of adult rats

A number of inflammatory mediators and cytokines were injected locally into the testis of adult rats in order to test their ability to induce leukocyte accumulation and increased vascular permeability (as studied by a carbon labelling technique). Human recombinant interleukin-1 beta (IL-1 beta) caused increased vascular permeability and leukocyte migration. All the other factors studied--histamine, serotonin, bradykinin, interleukin-1 alpha (IL-1 alpha), and a partially purified interleukin-1 alpha-like factor (tIL-1) from rat testis--did not induce any acute signs of increased vascular permeability or inflammatory response after local injection. It is suggested that local production of IL-1 beta from testicular macrophages could be responsible for the inflammation-like changes that are seen in rat testes after treatment with human chorionic gonadotrophin.