Dorsal hippocampal neural immune signaling regulates heroin-conditioned immunomodulation but not heroin-conditioned place preference

Repeated pairings of heroin and a context results in Pavlovian associations which manifest as heroin-conditioned appetitive responses and peripheral immunomodulation upon re-exposure to heroin-paired conditioned stimuli (CS). The dorsal hippocampus (DH) plays a key role in the neurocircuitry governing these context-heroin associations. Within the DH, expression of the pro-inflammatory cytokine interleukin-1β (IL-1β) is required for heroin-conditioned peripheral immunomodulation to occur. However, the role of signaling via IL-1 receptor type 1 (IL-1R1) has not been examined. Furthermore, it has not been evaluated whether the involvement of IL-1 in associative learning extends to classically conditioned appetitive behaviors, such as conditioned place preference (CPP). The first set of experiments investigated whether DH IL-1R1 signaling during CS re-exposure modulates heroin-conditioned immunomodulation and heroin-CPP. The second set of experiments employed chemogenetic techniques to examine whether DH astroglial signaling during CS re-exposure alters the same Pavlovian responses. This line of investigation is based on previous research indicating that astrocytes support hippocampal-dependent learning and memory through the expression of IL-1β protein and IL-1R1. Interestingly, IL-1R1 antagonism disrupted heroin-conditioned suppression of peripheral immune parameters but failed to alter heroin-CPP. Similarly, chemogenetic stimulation of Gi-signaling in DH astrocytes attenuated heroin-conditioned peripheral immunomodulation but failed to alter heroin-CPP. Collectively our data show that both IL-1R1 stimulation and astrocyte signaling in the DH are critically involved in the expression of heroin-conditioned immunomodulation but not heroin-CPP. As such these findings strongly suggest hippocampal neuroimmune signaling differentially regulates Pavlovian immunomodulatory and appetitive behaviors.

Activation of interleukin-1beta receptor suppresses the voltage-gated potassium currents in the small-diameter trigeminal ganglion neurons following peripheral inflammation

The glial cytokine, interleukin-1beta (IL-1beta), potentiates the excitability of nociceptive trigeminal ganglion (TRG) neurons via membrane depolarization following peripheral inflammation. Perforated patch-clamp technique was used this study to show that the mechanism underlying the excitability of small-diameter TRG neurons following inflammation is due to IL-1beta. Inflammation was induced by injection of complete Freund's adjuvant (CFA) into the whisker pad. The TRG neurons innervating the site of inflammation were identified by fluorogold (FG) labeling. The threshold for escape from mechanical stimulation applied to the orofacial area in inflamed rats was significantly lower than observed for control rats. IL-1beta at 1nM suppressed total voltage-gated K(+) currents in most TRG neurons (70%) under voltage-clamp conditions in control and inflamed rats. IL-1beta significantly decreased the total, transient (I(A)) and sustained (I(K)) currents in FG-labeled small-diameter TRG neurons in both groups. The IL-1beta-induced suppression of TRG neuron excitability was abolished by co-administration of ILra, an IL-1beta receptor blocker. The magnitude of inhibition of I(A) and I(K) currents by IL-1beta was significantly greater in inflamed rats than in controls. IL-1beta inhibited I(A) to a significantly greater extent than I(K). These results suggest that the inhibitory effect of I(A) and I(K) currents by IL-1beta in small-diameter TRG neurons potentiates neuronal excitability thereby contributing to trigeminal inflammatory hyperalgesia. These findings provide evidence for the development of voltage-gated K(+) channel openers and IL-1beta antagonists as therapeutic agents for the treatment of trigeminal inflammatory hyperalgesia.

Interleukin-1beta mediates proliferation and differentiation of multipotent neural precursor cells through the activation of SAPK/JNK pathway

Neural precursor cells (NPCs) have been experimentally used to repair the damaged nervous system either by exogenous transplantation or by endogenous activation. In post-injury inflammation, an array of cytokines including interleukin-1beta (IL-1beta) are released by host as well as invading immune cells and increased markedly. In the present study, we investigated the effects of IL-1beta on the survival, proliferation, differentiation and migration of NPCs as well as underlying intracellular signaling pathways. NPCs derived from the E16 rat brain were expanded in neurospheres that were found to express IL-1beta, IL-1RI and IL-1RII, but not IL-1alpha and IL-1ra. IL-1beta inhibited the proliferation of NPCs in a dose-dependent manner, an effect that can be reversed by IL-1ra, an antagonist for IL-1 receptor. This inhibitory effect of IL-1beta on NPCs proliferation resulted in part from its effect on increased apoptosis of NPCs. Moreover, IL-1ra did not affect NPCs lineage fate but rather inhibited GFAP expression in differentiated astrocytes. We also found that IL-1ra had no effect on the transmigration of NPCs in vitro. Finally, we showed that the effect of IL-1beta on NPCs proliferation and differentiation appeared to be mediated by SAPK/JNK, but not ERK, P38MAPK nor NF-kappaB pathways. These findings collectively suggest that the inflammatory environment following CNS injuries may influence the ability of NPCs to repair the damage.

Lipopolysaccharide-induced protein kinase D activation mediated by interleukin-1beta and protein kinase C

Protein kinase D (PKD), a newly described serine/threonine kinase, has been implicated in many signal transduction pathways. The present study was designed to determine whether and how PKD is activated in inflammation. The results demonstrated that lipopolysaccharide (LPS, 30 microg/ml) stimulated PKD and protein kinase C (PKC) phosphorylation in spinal neurons within 0.5 h, and the activation reached a maximum at 3 or 8 h and declined at 12 h. The phosphorylation could be inhibited by the selective inhibitors for PKC (100 nM), mainly for PKCalpha and PKCbeta, suggesting the involvement of the PKC pathway. Particularly, PKCalpha might be critical for LPS-induced PKD activation since the PKCbeta inhibitor (100 nM) observed no effect on the phosphorylation of PKD. Furthermore, the expression of interleukin-1beta (IL-1beta) was significantly induced by LPS within 0.5 h, and reached a maximum at 8 h. IL-1 receptor antagonist inhibited PKD and PKCs activation induced by LPS at a concentration of 50 nM and achieved maximum at 1000 nM. These results demonstrated for the first time that PKD could be activated by LPS in spinal neurons, might via the IL-1beta/PKCalpha pathway. Additionally, immunostaining showed an increase in number of phosphorylated PKD-immunoreactive cells of adult spinal dorsal horn induced by intraplantar injected carrageenan (2 microg/100 microl), and antisense oligodeoxynucleotide to IL-1 receptor type I (50 microg/10 microl, intrathecal injected) inhibited the PKD activation, suggesting an involvement of IL-1beta/PKD pathway in inflammation in adult spinal cord.

[Perspectives in clinical immunology]

Since the last years the better knowledge of immunologic mechanisms underlying autoimmune phenomena and rejection of allotransplants has been accompanied by an impressive production of new drugs: new inhibitors of purine and pyrimidine synthesis, as mycophenolate mofetil and leflunomide respectively, new inhibitors of calcineurin, such as tacrolimus, and target of rapamycine, such as sirolimus. Moreover, the tremendous advance in the methodology of producing monoclonal antibodies and the genetic engineering of proteins has led to a wide variety of biological agents, many of them have been approved as important new therapies for autoimmune diseases and against graft rejection. Monoclonal antibodies targeting IL-2 cytokine receptor have been shown to be useful in decrease the incidence of rejection. Moreover, monoclonal antibodies are available which target inflammatory cytokines, such as TNFalpha and IL-1, while other monoclonal antibodies may cause immune cell depletion, such as anti CD20 rituximab, or cause disruption of co-stimuli, like CTLA4Ig abatacept in the treatment of rheumatoid arthritis and anti CD11 efalizumab in the treatment of psoriasis. The new biologic agents have induced salutary clinical effects and extended the therapeutic option of patients not responding to existing treatments. The future looks brighter than ever as the recorded success fuels efforts to optimize the use of the biologic agents and extend their use in other diseases.

Role of brain IL-1β on fatigue after exercise-induced muscle damage

Brain cytokines, induced by various inflammatory challenges, have been linked to sickness behaviors, including fatigue. However, the relationship between brain cytokines and fatigue after exercise is not well understood. Delayed recovery of running performance after muscle-damaging downhill running is associated with increased brain IL-1β concentration compared with uphill running. However, there has been no systematic evaluation of the direct effect of brain IL-1β on running performance after exercise-induced muscle damage. This study examined the specific role of brain IL-1β on running performance (either treadmill or wheel running) after uphill and downhill running by manipulating brain IL-1β activity via intracerebroventricular injection of either IL-1 receptor antagonist (ra; downhill runners) or IL-1β (uphill runners). Male C57BL/6 mice were assigned to the following groups: uphill-saline, uphill-IL-1β, downhill-saline, or downhill-IL-1ra. Mice initially ran on a motor-driven treadmill at 22 m/min and −14% or +14% grade for 150 min. After the run, at 8 h (wheel cage) or 22 h (treadmill), uphill mice received intracerebroventricular injections of IL-1β (900 pg in 2 μl saline) or saline (2 μl), whereas downhill runners received IL-1ra (1.8 μg in 2 μl saline) or saline (2 μl). Later (2 h), running performance was measured (wheel running activity and treadmill run to fatigue). Injection of IL-1β significantly decreased wheel running activity in uphill runners ( P < 0.01), whereas IL-1ra improved wheel running in downhill runners ( P < 0.05). Similarly, IL-1β decreased and Il-1ra increased run time to fatigue in the uphill and downhill runners, respectively ( P < 0.01). These results support the hypothesis that increased brain IL-1β plays an important role in fatigue after muscle-damaging exercise.

MyD88-dependent IL-1 receptor signaling is essential for gouty inflammation stimulated by monosodium urate crystals

While it is known that monosodium urate (MSU) crystals cause the disease gout, the mechanism by which these crystals stimulate this inflammatory condition has not been clear. Here we find that the Toll/IL-1R (TIR) signal transduction adaptor myeloid differentiation primary response protein 88 (MyD88) is required for acute gouty inflammation. In contrast, other TIR adaptor molecules, TIRAP/Mal, TRIF, and TRAM, are not required for this process. The MyD88-dependent TLR1, -2, -4, -6, -7, -9, and -11 and IL-18 receptor (IL-18R) are not essential for MSU-induced inflammation. Moreover, MSU does not stimulate HEK cells expressing TLR1-11 to activate NF-kappaB. In contrast, mice deficient in the MyD88-dependent IL-1R showed reduced inflammatory responses, similar to those observed in MyD88-deficient mice. Similarly, mice treated with IL-1 neutralizing antibodies also showed reduced MSU-induced inflammation, demonstrating that IL-1 production and IL-1R activation play essential roles in MSU-triggered inflammation. IL-1R deficiency in bone marrow-derived cells did not affect the inflammatory response; however, it was required in non-bone marrow-derived cells. These results indicate that IL-1 is essential for the MSU-induced inflammatory response and that the requirement of MyD88 in this process is primarily through its function as an adaptor molecule in the IL-1R signaling pathway.

HEPATIC ISCHEMIA/REPERFUSION UPREGULATES THE SUSCEPTIBILITY OF HEPATOCYTES TO CONFER THE INDUCTION OF INDUCIBLE NITRIC OXIDE SYNTHASE GENE EXPRESSION

During hepatic ischemia/reperfusion (I/R), proinflammatory cytokines such as tumor necrosis factor alpha and interleukin (IL) 1beta stimulate the induction of inducible nitric oxide synthase (iNOS) in hepatocytes, followed by massive production of nitric oxide. We hypothesized that I/R upregulated the susceptibility of hepatocytes to confer the induction of iNOS gene expression. This study was designed to investigate whether cell susceptibility occurs in response to I/R and to delineate the mechanisms underlying the susceptibility. Hepatocytes were isolated from rats with hepatic I/R or sham, cultured, and treated with IL-1beta. The iNOS induction and its signal including inhibitor kappaB (IkappaB) kinase/nuclear factor kappaB (NF-kappaB) and Akt/type 1 interleukin 1 receptor (IL-1R1) were analyzed. Hepatocytes isolated from rats with I/R markedly increased the production of nitric oxide when stimulated by IL-1beta as compared with sham control. Ischemia/R also increased the levels of iNOS protein and its messenger RNA. Furthermore, I/R enhanced the activation of transcription factor NF-kappaB and the transactivation of iNOS promoter. However, I/R had no effects on the degradation of IkappaB and the nuclear translocation of p65 subunit of NF-kappaB. In contrast, I/R increased the phosphorylation of Akt and the upregulation of IL-1R1 induction, which is essential signal for the transcriptional activation of iNOS in addition to IkappaB kinase/NF-kappaB. These results demonstrate that I/R may augment hepatocyte susceptibility for the induction of iNOS gene expression through the enhancement of IL-1R1.

Involvement of Ca(2+)-induced Ca2+ releasing system in interleukin-1beta-associated adenosine release

Interleukin-1beta (IL-1beta) plays an important role in neuroprotective and neurodegenerative events in the central nervous system. To clarify the mechanism of controversial actions of IL-1beta, we determined the effect of IL-1beta, as well as the interaction between IL-1beta and Ca(2+)-induced Ca2+ releasing system (CICR), on adenosine releases in mice hippocampus using mini-slices method. Basal and K(+)-stimulated adenosine releases were regulated by two types of CICRs, including inositol-1,4,5-trisphosphate (IP3) receptor and ryanodine receptor. Lower concentration of IL-1beta increased both adenosine releases, whereas higher concentration did not affect their releases. The stimulatory effect of IL-1beta on basal adenosine release was reduced by removal of extracellular Ca2+ and IP3 receptor inhibitor, while the stimulatory effect of IL-1beta on K(+)-stimulated adenosine release was reduced by ryanodine receptor inhibitor. These results suggest that the potent effect of IL-1beta upon adenosine release might contribute to the neuroprotective action of IL-1beta, whereas IL-1beta-induced neurodegeneration might be due to the overload response of Ca2+ mobilization and the inactivation of adenosine exocytosis.

Causal links between brain cytokines and experimental febrile convulsions in the rat

PURPOSE

Despite the prevalence of febrile convulsions (FCs), their pathophysiology has remained elusive. We tested the hypothesis that components of the immune response, particularly the proinflammatory cytokine interleukin-1beta (IL-1beta) and its naturally occurring antagonist interleukin-1 receptor antagonist (IL-1ra) may play a role in the genesis of FC.

METHODS

Postnatal day 14 rats were treated with lipopolysaccharide (LPS; 200 microg/kg, i.p.) followed by a subconvulsant dose of kainic acid (1.75 mg/kg, i.p.). Brains were harvested at and 2 h after onset of FCs to measure brain levels of IL-1beta and IL-1ra. Separate groups of animals were given intracerebroventricular (ICV) injections of IL-1beta, or IL-1ra in an attempt to establish a causal relation between the IL-1beta/IL-1ra system and FCs.

RESULTS

Animals with FCs showed increased IL-1beta in the hypothalamus and hippocampus but not in the cortex compared with noFC animals that also received LPS and kainic acid. This increase was first detected in the hippocampus at onset of FCs. No detectable difference in IL-1ra was found in brain regions examined in either group. When animals were treated with IL-1beta ICV, a dose-dependant increase was noted in the proportion of animals that experienced FCs, whereas increasing doses of IL-1ra, given to separate groups of animals, were anticonvulsant.

CONCLUSIONS

Our results suggest that excessive amounts of IL-1beta may influence the genesis of FCs. This may occur by overproduction of IL-1beta, or by alteration in the IL-1beta/IL-1ra ratio in the brain after an immune challenge.

Ventricular enlargement in schizophrenia is associated with a genetic polymorphism at the interleukin-1 receptor antagonist gene

Magnetic resonance imaging (MRI) studies have shown some morphological and volumetric peculiarities in brains of schizophrenic patients. The authors explored the influence of genetic polymorphisms at interleukin-1beta (IL-1B) and interleukin-1 receptor antagonist (IL-1RN) genes on these abnormalities. Hippocampus, lateral ventricles, and dorsolateral prefrontal cortex gray matter volumes were measured in a sample of 23 DSM-IV diagnosed schizophrenic patients of Spanish origin using MRI scans; MRI data were adjusted for age and brain volume using regression parameters from a healthy control group (n = 45). IL-1B and IL-1RN genes, involved in neurodevelopment and neurodegenerative processes, were analyzed in the patient sample. Patients carrying VNTR-allele*2 of IL-1RN gene showed a significant enlargement of both left (P = 0.002) and right (P = 0.01) ventricles. Sex and illness duration were controlled for in the analyses. Our results, though preliminary, suggest that IL-1RN gene might contribute to the ventricular volumetric changes observed in schizophrenic patients.

Modulation of interleukin-1 receptors followed by endotoxin lipopolysaccharide treatment in the mouse AtT-20 pituitary tumor cell line

OBJECTIVE

We have previously reported the characterization and regulation of interleukin-1 (IL-1) receptors utilizing [125I]IL-1 binding assay in male C57BL/6 mice and the mouse AtT-20 pituitary tumor cells. In the present study, we examine IL-1 receptors using an immunoblotting method to further characterize the mechanisms regulating the interactions of IL-1 receptors with endotoxin, lipopolysaccharide (LPS).

METHODS

We established Western blotting for IL-1 receptors using AtT-20 mouse pituitary tumor cells.

RESULTS

Several bands were seen; however, only the 105-kD band was neutralized with a 5-fold excess of IL-1 receptor- blocking peptides, suggesting that this band is specific for IL-1 receptors. Next, we investigated the effect of LPS and IL-1beta on IL-1 receptors. Treatment of AtT-20 cells with 0.01 microg/ml of LPS did not affect IL-1 receptors. In contrast, 1 microg/ml of LPS significantly increased IL-1 receptors in AtT-20 cells compared with the control group. In addition, [125I]IL-1beta binding was markedly increased followed by 1 microg/ml of LPS. In contrast, 1 nM recombinant human IL-1beta significantly decreased IL-1 receptors in AtT-20 cells compared with the control group although treatment of AtT-20 cells with 0.01 nM IL-1beta did not affect IL-1 receptors. LPS (0.1 and 1 microg/ml) did not affect IL-1beta concentrations in the medium of AtT-20 cell culture. IL-1beta concentrations in the homogenates from AtT-20 cells were significantly decreased after 1 microg/ml of LPS treatment but not after 0.01 microg/ml LPS.

CONCLUSIONS

These data demonstrate that LPS and IL-1beta differentially modulate IL-1 receptors in AtT-20 cells and LPS-induced modulation of IL-1 receptors may provide a novel mechanism for the actions of LPS to alter pituitary function during endotoxemia. Additional in vivo studies are necessary to determine the physiological relevance of this in vitro phenomenon.

Cytokine responses of human gingival fibroblasts to Actinobacillus actinomycetemcomitans cytolethal distending toxin

Actinobacillus actinomycetemcomitans is implicated in the pathogenesis of localized aggressive periodontitis, and has the capacity to express a cytolethal distending toxin (Cdt). Gingival fibroblasts (GF) are resident cells of the periodontium, which can express several osteolytic cytokines. The aims of this study were a) to investigate the role of Cdt in A. actinomycetemcomitans-induced expression of osteolytic cytokines and their cognate receptors in GF and b) to determine if the previously demonstrated induction of receptor activator of NFkappaB ligand (RANKL) by A. actinomycetemcomitans is mediated by these pro-inflammatory cytokines or by prostaglandin E(2) (PGE(2)). A. actinomycetemcomitans clearly induced interleukin (IL)-6, IL-1beta, and to a minimal extent, tumor necrosis factor (TNF)-alpha mRNA expression. At the protein level, IL-6 but not IL-1beta or TNF-alpha expression was stimulated. The mRNA expression of the different receptor subtypes recognizing IL-6, IL-1beta and TNF-alpha was not affected. A cdt-knockout strain of A. actinomycetemcomitans had similar effects on cytokine and cytokine receptor mRNA expression, compared to its parental wild-type strain. Purified Cdt stimulated IL-6, but not IL-1beta or TNF-alpha protein biosynthesis. Antibodies neutralizing IL-6, IL-1 or TNF-alpha, and the PGE(2) synthesis inhibitor indomethacin, did not affect A. actinomycetemcomitans-induced RANKL expression. In conclusion, a) A. actinomycetemcomitans induces IL-6 production in GF by a mechanism largely independent of its Cdt and b) A. actinomycetemcomitans-induced RANKL expression in GF occurs independently of IL-1, IL-6, TNF-alpha, or PGE(2).

Rosiglitazone induces interleukin-1 receptor antagonist in interleukin-1beta-stimulated rat synovial fibroblasts via a peroxisome proliferator-activated receptor beta/delta-dependent mechanism

OBJECTIVE

To study the potency of 2 peroxisome proliferator-activated receptor gamma (PPARgamma) agonists, 15-deoxy-Delta(12,14)-prostaglandin J(2) (15-deoxy-PGJ(2)) and rosiglitazone, to modulate the expression of interleukin-1 receptor antagonist (IL-1Ra) in rat synovial fibroblasts.

METHODS

Levels of messenger RNA for IL-1Ra and PPAR isotypes (alpha, beta/delta, gamma) were assessed by real-time polymerase chain reaction in rat synovial fibroblasts exposed to 10 ng/ml of IL-1beta. PPAR levels were assessed by Western blotting and secreted IL-1Ra levels by immunoassay. The potency of PPARgamma agonists and the PPARbeta/delta agonist GW-501516 on IL-1Ra levels was tested in the range of 1-10 microM and at 100 pM, respectively. The contribution of PPARgamma to the effects of rosiglitazone on IL-1Ra secretion was examined either by its overexpression or by inhibition using wild-type or dominant-negative constructs and the antagonist GW-9662 (10 microM), respectively. The dominant-negative strategy was also performed to investigate the possible contribution of PPARbeta/delta and NF-kappaB activation.

RESULTS

IL-1beta-induced IL-1Ra production was increased by 10 microM rosiglitazone but was reduced dose-dependently by 15-deoxy-PGJ(2). Both agonists lowered IL-1beta secretion, but rosiglitazone alone reduced the imbalance of IL-1beta/IL-1Ra toward basal levels. Enhancement of IL-1beta-induced IL-1Ra production by rosiglitazone was not affected by PPARgamma overexpression or by its inhibition with dominant-negative PPARgamma or GW-9662. Inhibition of NF-kappaB was also ineffective against rosiglitazone but abolished the stimulating effect of IL-1beta on IL-1Ra. All PPAR isotypes were expressed constitutively in rat synoviocytes, but PPARgamma decreased dramatically upon IL-1beta exposure, whereas PPARbeta/delta remained stable. Dominant-negative PPARbeta/delta abolished the enhancement of IL-1Ra by rosiglitazone, whereas GW-501516 reproduced the effect of rosiglitazone on IL-1Ra secretion.

CONCLUSION

Rosiglitazone stimulates IL-1Ra production by a PPARbeta/delta mechanism in activated rat synovial fibroblasts, further contributing to its potential antiarthritic properties and opening new perspectives for the modulation of inflammatory genes by specific PPAR agonists in articular cells.

Increased soluble interleukin-1 receptor type II proteolysis in the endometrium of women with endometriosis

Numerous functional changes were observed in the intrauterine endometrial tissue of women with endometriosis. Our previous studies revealed a marked decrease in the expression of interleukin-1 receptor type 2 (IL-1RII), a decoy receptor known for its ability to buffer IL-1 effects. The aim of the present study was to assess whether post-translational mechanisms such as proteolysis may contribute to the down-regulation of IL-1RII levels. Our data showed that soluble IL-1RII (sIL-1RII) concentrations released by freshly cultured endometrial tissue were significantly lower in women with endometriosis than in normal women (P < 0.01) and further revealed a statistically significant correlation between increased proteolysis and decreased sIL-1RII levels (P < 0.05; r = -0.47). (125)I-labelled soluble recombinant human IL-1RII ([(125)I]srhIL-1RII) was significantly more degraded in culture supernatant of tissues from women with endometriosis compared to normal women (P < 0.05), and natural tissue inhibitor of matrix metalloproteinase (TIMP)-1 inhibited [(125)I]srhIL-1RII degradation. Incubation of srhIL-1RII with active rhMMP-9 resulted in a dose-dependent degradation of srhIL-1RII as analysed by western blotting. Dual immunofluorescence showed an increased immunostaining for matrix metalloproteinase-9 in situ in the endometrial tissue of women with endometriosis compared to normal women and a decreased immunostaining for IL-1RII. The present study showed a reduced release of sIL-1RII by the endometrial tissue of women with endometriosis and revealed a proteolytic post-translational mechanism which may be involved in the down-regulation of IL-1RII levels. This may enhance IL-1-mediated activation of endometrial cells and contribute to the local immuno-inflammatory process observed in endometriosis patients.

Cycloprodigiosin up-regulates inducible nitric oxide synthase gene expression in hepatocytes stimulated by interleukin-1beta

The proinflammatory cytokine interleukin-1beta stimulates inducible nitric oxide synthase (iNOS) gene expression in hepatocytes via activation of a transcription factor, nuclear factor-kappaB (NF-kappaB). Nitric oxide has diverse cytoprotective and toxic effects. Cycloprodigiosin is an anticancer drug that induces apoptosis through NF-kappaB-dependent mechanisms. This study investigated whether cycloprodigiosin influenced NF-kappaB activation and induction of iNOS by interleukin-1beta. Cycloprodigiosin alone had no effect on NO production by primary cultured rat hepatocytes. Simultaneous addition of cycloprodigiosin and interleukin-1beta markedly stimulated the induction of iNOS mRNA and protein compared with addition of interleukin-1beta alone, resulting in overproduction of NO. Cycloprodigiosin had no effect on degradation of the inhibitory subunit of NF-kappaB (IkappaBalpha), but lessened the recovery of IkappaBalpha levels. The electrophoretic mobility shift assay revealed that cycloprodigiosin caused an increase of NF-kappaB activation. Consistent with this observation, cycloprodigiosin promoted the translocation of p65 (a subunit of NF-kappaB) to the nucleus. Furthermore, this drug enhanced expression of the type 1 interleukin-1 receptor, and this action showed similar concentration-dependence to its induction of iNOS. These results indicate that cycloprodigiosin up-regulates the induction of iNOS by increasing NF-kappaB activation, at least partly through enhancement of type 1 interleukin-1 receptor expression. By regulating the expression of NF-kappaB-dependent genes, such as iNOS, cycloprodigiosin administration may increase NO production during hepatic injury.

Early response to bleomycin is characterized by different cytokine and cytokine receptor profiles in lungs

The sensitivity to the fibrosis-inducing effect of bleomycin varies considerably from species to species, the reasons for which are unknown. The variability of the response in different strains of mice is well documented. Recent evidence indicates that the upregulated expression of cytokines and cytokine receptors may be involved. We evaluated the expression pattern of some cytokines and their receptors in C57Bl/6J bleomycin-sensitive and Balb/C bleomycin-resistant mice. Animals from both strains received, under ether anesthesia, either saline (50 microl) or bleomycin (0.1 U/50 microl) intratracheally. At various times after the treatment, the lungs were analyzed for cytokines and cytokine receptors by histochemistry and their mRNA by RNase protection assay. A significantly increased expression of TNF-alpha and IL-1beta was observed in both strains. However, an upregulated lung expression for TNF-alpha and IL-1 receptors was observed in C57Bl/6J-sensitive animals only. This profile is evident from 63 h onward. In addition to TNF-alpha, bleomycin administration also resulted in the upregulated expression of TGF-beta in the lungs of both strains at 8 h and in an enhanced expression of TGF-beta receptors I and II in C57Bl/6J mice only. The upregulation of TGF-beta receptor expression was preceded in this strain by an increased expression of IL-4, IL-13, and IL-13 receptor-alpha (at 8 h after bleomycin) and followed by an upregulation of gp130 and IL-6. The difference we observed in the cytokine receptor profile may offer an additional explanation for the different fibrogenic response of the two mouse strains to bleomycin.

A peptide derived from the human leptin molecule is a potent inhibitor of the leptin receptor function in rabbit endometrial cells

In this article we show that rabbit endometrial cells express leptin receptor and that human leptin triggers phosphorylation of signal transducer and activator of transcription 3 and up-regulates the expression of interleukin- 1 receptor type I as was previously found in human endometrial cells. Interestingly, leptin also upregulates the secretion of leukemia inhibitory factor and expression of its receptor by rabbit endometrial cells. Analysis of a structural model of the leptin-leptin receptor complex suggested that helices I and III of the human leptin structure were likely sites of interaction with the cytokine binding domain of leptin receptor. Accordingly, we synthesized a peptide (LPA-2) comprising helix III (residues 70-95) and investigated its ability to inhibit leptin receptor function. The effects of LPA-2 were assayed in rabbit endometrial cells, and an antileptin receptor antibody and a scrambled version of LPA-2 were used as positive and negative controls, respectively. LPA-2 binds specifically and with high affinity (Ki ~ 0.6 x 10-10 M) to leptin receptor and is a potent inhibitor of its functions in rabbit endometrial cells. Because leukemia inhibitory factor and interleukin- 1 have been implicated in embryo implantation, our results raise the possibility that the LPA-2-induced inhibition of leptin receptor may be exploited to study the actions of leptin in endometrium and in other tissues under conditions characterized by abnormal leptin production.

Cytokines and peripheral analgesia

Tissue damage causes an inflammatory response in which cytokines contribute to a painful state. Local inflammation also leads to an enhanced expression of opioid peptides such as END within immune cells of inflamed tissue. These endogenous substances can be released by "releasing factors" such as CRF and IL-4 via activation of their receptors on the cell surface of inflammatory cells. Local application of CRE or IL-1 into inflamed tissue results in significant analgesia which is most likely mediated by a release of opioid peptides from immune cells within inflamed tissue. This mechanism of pain inhibition also seems to have a physiological role. Upon certain stressful stimuli analgesic effects seem to be mediated by a release of opioid peptides and a subsequent activation of peripheral opioid receptors. Locally expressed CRF but not IL-1 appear to trigger this release. Thus, inflammatory pain can be modulated both by exogenous CRF and IL-1 as well as endogenous CRF. These mechanisms are based on interaction between the immune and nervous systems. Both the initiation of pain and its control can be regarded as the body's response to prevent further injury, to support wound healing and to return to a normal function as quickly as possible.

Morphological correlates of immune-mediated peripheral opioid analgesia

The immune system is a source of opioid peptides and plays an important role in the control of inflammatory pain. Inflammation not only increases the opioid receptor expression in DRG neurons but also enhances transport and accumulation of opioid receptors on the peripheral terminals of sensory neurons. Immune cells containing opioid peptides migrate to the inflamed tissue. This is orchestrated by adhesion molecules up-regulated on vessel endothelia and co-expressed by opioid-containing immunocytes. The peptides are secreted by stressful stimuli, CRF and cytokines and the corresponding receptors are present on opioid-expressing leukocytes. The opioids bind to their receptors localized on peripheral sensory nerves leading to pain inhibion. In the more distant future, these findings might stimulate the development of novel analgesics based on enhancing the transport and release of immune-derived opioid peptides into injured tissue.

Interleukin-1 beta protects neurons via the interleukin-1 (IL-1) receptor-mediated Akt pathway and by IL-1 receptor-independent decrease of transmembrane currents in vivo

Recently, we have demonstrated that tumor necrosis factor-alpha (TNF-alpha) rescues retinal ganglion cells (RGCs) from retrograde cell death in vivo after axotomy of the optic nerve. The mechanism of RGC rescue was dependent on TNF-receptor I-mediated potassium current reduction and consecutive activation of the phosphatidylinositol 3-kinase (PI3-K)/Akt pathway. Here, we present evidence that interleukin-1 beta (IL-1 beta) also promotes RGC survival, but shows distinct differences with respect to its neuroprotective mechanisms. Using whole-cell and outside-out patch-clamp techniques, we observed that IL-1 beta decreased both inward sodium current amplitudes and outward potassium current amplitudes. Counteracting these effects by sodium or potassium channel opening inhibited the survival-promoting effects of this cytokine. IL-1 beta-induced current reduction could not be abolished by the interleukin-1 receptor antagonist, indicating that the electrophysiological effects of IL-1 beta are independent of interleukin-1 receptor I (IL-1RI) activation. Western blot analysis revealed an IL-1 beta-induced IL-1RI-dependent upregulation of phospho-Akt. Antagonism of the survival-promoting effects of IL-1 beta by PI3-K inhibition revealed the functional relevance of the PI3-K/Akt pathway in IL-1 beta-induced signal transduction in vivo.

IL-1beta-dependent neurological effects of the whole cell pertussis vaccine: a role for IL-1-associated signalling components in vaccine reactogenicity

Immunization with the whole cell pertussis vaccine (Pw), but not the acellular pertussis vaccine (Pa), is associated with a number of neurological side effects. Previously, we have demonstrated a role for interleukin-1beta (IL-1beta) in Pw reactogenicity. Here we report that parenteral Pw administration resulted in a concomitant increase IL-1 type I receptor (IL-1RI) mRNA and a decrease in IL-1 type II receptor (IL-1RII) mRNA expression in the murine hypothalamus. These Pw-induced changes were accompanied by an increase in caspase-1 and interleukin-1beta (IL-1beta), and were associated with increased activity of the stress-activated kinase, p38. In contrast, immunization with Pa failed to activate pro-inflammatory IL-1 responses but resulted in increased IL-1 receptor antagonist (IL-1ra) production. These results suggest that the neurological effects of Pw are associated with central activation of IL-1beta and IL-1-associated signalling components.

PDGF enhancement of IL-1 receptor levels in smooth muscle cells involves induction of an attachment-regulated, heparan sulfate binding site (IL-1RIII)

This study shows that increase in IL-1 receptor levels by platelet derived growth factor (PDGF) involves an enhancement of a matrix-dependent, low-affinity receptor that constitutes a heparan sulfate. Fibronectin attachment caused pronounced alterations in IL-1 receptor function in smooth muscle cells, involving a pronounced increase in cell surface binding from an average of 2,000 up to approximately 8,000 receptors/cell and an increase in affinity (K(a)) of the type I receptor from 1.8 +/- 0.9 x 10(9) to 3.7 +/- 0.5 x 10(9) M(-1). PDGF stimulation similarly enhanced the level of cell surface binding by between 30% and 100%, with, in general, less effect on cells plated on fibronectin. Further, PDGF had a pronounced effect on the type I receptor affinity in the absence of matrix attachment, increasing the K(a) from 1.77 +/- 0.93 x 10(9) to 5.1 +/- 2.1 x 10(9) M(-1). Scatchard analyses revealed that PDGF, similarly to fibronectin attachment, caused enhancement of a second low-affinity binding site. Antibody blocking showed that approximately 50% of the attachment-induced increase was independent of type I receptor binding. Further, a similar fraction of the cell surface interaction was blocked by soluble heparan sulfate and dependent on cell binding to the heparan binding site. Cross-linking demonstrated that, in addition to the type I receptor, IL-1 bound to a second high molecular weight complex of 300 kd, induced by fibronectin attachment as well as by PDGF in the absence of matrix. Biochemical analyses demonstrated that this second site constitutes a heparan sulfate, which directly interacted with the type I receptor after recruitment to the complex, and which bound up to 50% and 25% of the ligand after fibronectin attachment and PDGF stimulation, respectively. The data show that PDGF induces an attachment-regulated low-affinity IL-1 binding site in smooth muscle cells, constituting a heparan sulfate. Correlation of the recruitment of this component to the IL-1 receptor complex with structural regulation of receptor function and enhancement of IL-1-mediated responses suggests that this is a significant mechanism in PDGF augmentation of local inflammatory responses during vessel wall pathogenesis.

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.

Functional analysis of the interleukin-1-receptor-associated kinase (IRAK-1) in interleukin-1 beta-stimulated nuclear factor kappa B (NF-kappa B) pathway activation: IRAK-1 associates with the NF-kappa B essential modulator (NEMO) upon receptor stimulation

The interleukin-1 (IL-1)-receptor-associated kinase (IRAK-1) is essential for IL-1-stimulated nuclear factor kappa B (NF-kappa B) activation. To study the role of IRAK-1 in IL-1 beta signalling, we have generated a set of IRAK-1 variants that express distinct domains of IRAK-1 either alone or in combination and have examined their effects on an NF-kappa B-responsive reporter in HeLa cells. Unlike full-length IRAK-1, the deletion mutants were unable to activate NF-kappa B in the absence of cytokine stimulation. However, an IRAK-1 variant lacking only the N-terminal domain retained the ability of the full-length protein to potentiate both IL-1 beta and tumour necrosis factor alpha (TNF alpha)-induced NF-kappa B activation. In contrast, expression of the N-terminus or the C-terminus of IRAK-1, or a fusion protein incorporating both domains, inhibited both IL-1 beta- and TNF alpha-induced effects. Expression of an IRAK-1 variant lacking only the C-terminal domain preferentially inhibited IL-1 beta versus TNF alpha-induced NF-kappa B activation. These data suggest that the C-terminal domain may link IRAK-1 to downstream signalling components common to both the IL-1 and TNF pathways. Furthermore, we have demonstrated that endogenous IRAK-1 becomes phosphorylated upon IL-1 beta treatment and can be detected along with NF-kappa B essential modulator (NEMO) and I kappa B kinase beta (IKK beta) in high-molecular-mass complexes of 600-800 kDa. Moreover, IRAK-1 could be detected in NEMO immunoprecipitates from IL-1 beta-stimulated cells. We conclude that IRAK-1 mediates IL-1 beta signal transduction through a ligand-dependent association of IRAK-1 with the IKK complex.

Lipopolysaccharide stimulates norepinephrine efflux from the rat hypothalamus in vitro: blockade by soluble IL-1 receptor

Lipopolysaccharide (LPS) has been shown to produce a number of central and neuroendocrine effects. While all mechanisms are not clear, it is believed that central catecholamines could be involved in this process. This study was done to investigate the direct effects of LPS on norepinephrine (NE) efflux from the medial basal hypothalamus in adult male rats using a combination of an in vitro incubation system and high performance liquid chromatography with electrochemical detection. Basal NE efflux was determined by incubating the hypothalami with Krebs Ringers Henseleit (KRH) alone for 60 min. Then, the hypothalami were incubated with KRH alone (control) or KRH containing 100 ng or 200 ng of LPS, 15 microg of soluble IL-1 receptor (sIL-1R) or a combination of 200 ng LPS and 5 or 15 microg of sIL-1R. In the third incubation period, the hypothalami were incubated with KRH alone to check for the residual effects of LPS if any. In the fourth incubation period, the hypothalami were incubated with high K+KRH to check for tissue viability. Incubation with LPS stimulated NE efflux in a dose-dependent manner. Incubation of hypothalami with 200 ng of LPS and 15 microg of sIL-1R completely blocked LPS-induced increase in NE efflux. These results indicate that LPS could act directly on the hypothalamus to stimulate the efflux of NE and this effect is probably mediated through IL-1.

Strain-dependent difference in inducible nitric oxide synthesis (iNOS) expression in rat pancreatic islets correlates with interferon regulating factor 1 (IRF-1) and heat shock protein 70 (HSP70) expression

Nitric oxide (NO) may be a necessary but not sufficient mediator of cytokine-mediated, selective beta-cell destruction. Previously, we have described a difference in NO-dependent IL-1beta sensitivity in vivo and in vitro of pancreatic islets from two rat strains, Brown Norway (BN) and Wistar Kyoto (WK), the latter being the more sensitive strain. Here we investigated whether strain-dependent, differential islet iNOS expression was associated with differences in islet expression of the IL-1 receptor type 1(IL-1RI) or interferon regulating factor 1 (IRF-1), and/or caused differences in HSP70 expression, a marker of cell defence against oxidative stress.

METHODS

isolated islets from both rat strains were exposed to increasing concentrations of IL-1beta (0-150 pg/ml) for 24 hours or for varying culture periods (4-48 hours) to 15 pg/ml of IL-1beta.

MEASUREMENTS

accumulated insulin and nitrite release into incubation medium, and islet mRNA and protein expression of iNOS, IL-1RI, IRF-1 and HSP70 by semi-quantitative RT-PCR and Western blotting.

RESULTS

Higher insulin and lower nitrite release into the incubation medium were seen for BN compared to WK rats islets in both dose- and time-response experiments. IRF-1 expression preceded iNOS expression and was more pronounced in WK than in BN islets. No strain differences were observed for islet expression of IL-1RI. A strain-dependent HSP70 expression in response to IL-1beta with the highest levels in WK rat islets following iNOS expression was seen.

CONCLUSION

There was a strain-dependent difference in iNOS expression which was associated with IRF-1 and HSP70 expression.

Down regulation of interleukin 1beta production in human osteoarthritic synovial tissue and cartilage cultures by aminoguanidine

OBJECTIVE

To evaluate the effect of aminoguanidine (AG) on de novo interleukin 1beta (IL1beta), nitric oxide (NO), and interleukin 1 receptor antagonist (IL1ra) production by osteoarthritic human synovial tissue and articular cartilage cultures.

METHODS

Synovial tissue and cartilage, obtained during surgery from 29 patients undergoing total knee or hip replacement for osteoarthritis, were cut into small pieces and cultured in the presence or absence of lipopolysaccharide (LPS) and test materials. IL1beta, IL1ra, and NO were determined in culture media. The inducible nitric oxide synthase inhibitor, AG, was added to cultures in various concentrations (0.3-3 mmol/l).

RESULTS

In synovial tissue cultures AG (0.3, 1, and 3 mmol/l) decreased LPS (1 microg/ml) stimulated IL1beta and NO release in the media in a dose dependent manner (p<0.05 at 1 mmol/l and p<0.05 at 0.3 mmol/l, respectively). In articular cartilage cultures AG (0.3, 1, and 3 mmol/l) decreased LPS (1 microg/ml) stimulated IL1beta and NO release in the media in a dose dependent manner (p<0.05 at 1 mmol/l and p<0.01 at 0.3 mmol/l, respectively). Hydrocortisone (5 microg/ml) also significantly decreased LPS stimulated IL1beta release in media of synovial tissue and cartilage cultures and NO in media of synovial cultures. AG (0.3, 1, and 3 mmol/l) decreased LPS (1 microg/ml) stimulated IL1ra levels in media of synovial tissue cultures in a dose dependent manner (p<0.05 at 1 mmol/l) but increased LPS (1 microg/ml) stimulated IL1ra release in media of cartilage cultures (p<0.01 at 3 mmol/l). The NO donor, nitroprusside (10, 30, 100, and 300 microg/ml) stimulated IL1beta release in media of synovial tissue cultures in a dose dependent manner (p<0.01 at 100 microg/ml). AG and nitroprusside at the concentrations used had no toxic effect on human synovial cells.

CONCLUSIONS

NO synthase inhibitors may modulate osteoarthritis and articular inflammatory processes not only by decreasing NO synthesis but also by their effects on ILbeta and IL1ra production.

The role of cytokines in physiological sleep regulation

Several growth factors (GFs) are implicated in sleep regulation. It is posited that these GFs are produced in response to neural activity and affect input-output relationships within the neural circuits where they are produced, thereby inducing a local state shift. These GFs also influence synaptic efficacy. All the GFs currently identified as sleep regulatory substances are also implicated in synaptic plasticity. Among these substances, the most extensively studied for their role in sleep regulation are interleukin-1beta (IL-1) and tumor necrosis factor alpha (TNF). Injection of IL-1 or TNF enhances non-rapid eye movement sleep (NREMS). Inhibition of either IL-1 or TNF inhibits spontaneous sleep and the sleep rebound that occurs after sleep deprivation. Stimulation of the endogenous production of IL-1 and TNF enhances NREMS. Brain levels of IL-1 and TNF correlate with sleep propensity; for example, after sleep deprivation, their levels increase. IL-1 and TNF are part of a complex biochemical cascade regulating sleep. Downstream events include nitric oxide, growth hormone releasing hormone, nerve growth factor, nuclear factor kappa B, and possibly adenosine and prostaglandins. Endogenous substances moderating the effects of IL-1 and TNF include anti-inflammatory cytokines such as IL-4, IL-10, and IL-13. Clinical conditions altering IL-1 or TNF activity are associated with changes in sleep, for example, infectious disease and sleep apnea. As our knowledge of the biochemical regulation of sleep progresses, our understanding of sleep function and of many clinical conditions will improve.

Physiological significance of the interleukin 1 receptor accessory protein

Interleukin 1 receptor accessory protein (IL-1RAcP) is an essential signal-transducing component of the IL-1 receptor type I. The recent availability of IL-1RAcP-deficient (KO) mice allows to study the in vivo function of IL-1RAcP. Animals were injected intraperitoneally with rat recombinant IL-1beta (200 ng/mouse), lipopolysaccharide (LPS, 5 microg/mouse), or subjected to 1-hour restraint stress. Neuroendocrine and immune parameters were measured 2 h after IL-1 or LPS injection or just after restraint. In wild-type controls, IL-1 and LPS activated the hypothalamic-pituitary-adrenal axis and increased plasma IL-6. In KO mice, the plasma levels of corticosterone and IL-6 increased after LPS, but not after rat recombinant IL-1beta. The LPS-induced depression of the lymphoproliferation was similar in wild-type and KO mice. Finally, the 1-hour restraint was able to increase the plasma levels of corticosterone in KO mice. These results show that IL-1RAcP is essential for physiological activities of peripheral IL-1, as it was previously demonstrated for those of brain IL-1. However, using IL-1RAcP KO mice, we were unable to demonstrate a specific role of endogenous IL-1 during LPS-induced inflammation. Moreover, stress-induced activation of the hypothalamic-pituitary-adrenal axis may occur in the absence of the IL-1-transducing receptor, IL-1RAcP.

Clostridium difficile toxin: cytoskeletal changes and lactate dehydrogenase release in hepatocytes

BACKGROUND

We have found that Clostridium difficile toxins can evoke hepatocyte acute-phase protein synthesis, and that this effect is dependent on a functioning interleukin-1 (IL-1) receptor. The present study was undertaken to determine if C. difficile toxicity, as determined by actin rearrangement and lactate dehydrogenase (LDH) release, also requires a functioning IL-1 receptor.

METHODS

Primary hepatocyte cultures were prepared from normal mice, knockout mice deficient in the IL-1-converting enzyme (ICE), and knockout mice deficient in the IL-1 p80 receptor. Hepatocytes were treated for 24 h with C. difficile culture extract, purified C. difficile toxin A, or purified C. difficile toxin B. The actin cytoskeleton was examined using confocal microscopy, and LDH release was measured by spectrophotometric analysis.

RESULTS

C. difficile culture extract, toxin A, and toxin B induced collapse of the actin cytoskeleton in hepatocytes from normal mice. Hepatocytes from both the ICE-deficient mice and the IL-1 p80 receptor-deficient mice demonstrated similar responses to both toxins. These toxins also induced significant LDH release in a concentration-dependent fashion in the normal hepatocytes and the ICE-deficient hepatocytes. However, no significant increase in LDH release was observed in hepatocytes from IL-1 p80 receptor-deficient mice.

CONCLUSIONS

C. difficile toxins induce actin cytoskeletal collapse independent of IL-1 or the IL-1 receptor. In contrast, toxin-stimulated LDH release was dependent on the presence of the IL-1 receptor. Thus, separate pathways appear to mediate toxic effects as manifested by actin rearrangement and LDH release.

Aspirin-induced increases in soluble IL-1 receptor type II concentrations in vitro and in vivo

This study examined the influence of low-dose aspirin on interleukin (IL)-1alpha , IL-1 receptor antagonist (IL-1ra), and soluble receptor type II (sIL-1RII) secretion in vivo and in vitro. Blood mononuclear cells were isolated from healthy young men who ingested 81 mg of aspirin on alternate days for 2 weeks and from unmedicated controls. Aspirin had minor effects on ex vivo secretion of IL-1beta and no influence on IL-1ra. In contrast, unstimulated ex vivo secretion of sIL-1RII was over twice as high by cells from aspirin-treated subjects (1115+/-123 vs. 460+/-77 pg/mL, P = 0.02). Lipopolysaccharide-stimulated sIL-1RII secretion was influenced similarly. Plasma sIL-1RII concentrations were 23% higher in aspirin-treated subjects (10.2+/-0.6 vs. 8.4+/-0.3 ng/mL, P = 0.03). In addition, cells from unmedicated subjects cultured in vitro with aspirin (10 microg/mL) secreted significantly greater amounts of sIL-1RII. Thus, low-dose aspirin therapy may prevent inflammation by increasing soluble receptor secretion, thereby preventing IL-1 from binding target cells.

Dexamethasone regulation of interleukin-1-receptors in the hippocampus of Theiler's virus-infected mice: effects on virus-mediated demyelination

Intracerebral (i.c.) inoculation of susceptible strains of mice with Theiler's murine encephalomyelitis virus (TMEV) results in immune-mediated demyelinating disease. Interleukin-1 receptors are expressed in the brain of mice, in particular in the hippocampus, and have been implicated in neuroimmunoendocrine interactions. In the present study we investigated the regulation of interleukin-1 receptors in the hippocampus of a susceptible (SJL/J) and a resistant (BALB/c) strain of mice infected with TMEV, at different time intervals of the disease. Our results show that interleukin-1 receptors in the hippocampus were decreased in TMEV-infected mice at early times post-infection (10 and 14 days p.i.). The reduction in interleukin-1 receptors only occurred in the susceptible strain of mice (SJL/J), whereas interleukin-1 binding in the hippocampus of TMEV-infected resistant mice (BALB/c) showed values similar to those in control animals. The TMEV-induced down-regulation of interleukin-1 receptors was secondary to a marked decrease in the affinity of the receptor (control: Kd = 10.5 pM; TMEV: Kd = 1.30 pM) accompanied by a decrease in receptor number (control: Bmax = 2.189 fmol/mg protein; TMEV: B max = 0.84 fmol/mg protein). We also investigated the effects of glucocorticoid treatment on the regulation of hippocampal interleukin-1 receptors of TMEV-infected mice. Dexamethasone treatment in the early phase (500 microg/kg or 1 mg/kg during days 5-10 p.i.) of the disease significantly reversed the deficits in hippocampal interleukin-1 receptors observed at 10 days p.i. in SJL/J mice, and suppressed neurological signs of demyelination. These results suggest that: (i) the reduction of interleukin-1 receptors may be a consequence, at least in part, of local production of interleukin-1 at early times during TMEV infection; (ii) interleukin-1 seems to be a critical factor for the susceptibility to TMEV-induced demyelination and (iii) the protective effect of dexamethasone appears to be related to its ability to reverse the reduction in interleukin-1 receptors during the early disease. These results suggest that interleukin-1 is a pivotal mediator in TMEV-induced demyelination.

Interleukin-1 alpha induced cyclooxygenase-2 expression in bone-derived endothelial cells

Histological studies have suggested that vascular endothelial cells in bone are members of a complex network that regulates bone development and remodeling by producing soluble factors or by mediating cell-cell adhesion. To clarify the role of bone-derived endothelial cell lines (BDECs) in bone remodeling, we established several clones of BDECs from the femurs of BALB/c mice after transformation with the SV40 virus. Then we examined the response of these clones to interleukin-1alpha (IL-1alpha). IL-1alpha is known to induce bone resorption in part by increasing the expression of cyclooxygenase-2 (COX-2) that is associated with the production of PGE2 in osteoblast-lineage cells. Treating the primary and established BDECs with IL-1alpha induced COX-2 mRNA expression. A transcriptional activation assay revealed that the treatment with IL-1alpha increased COX-2 promoter activity in a dose-dependent manner, and IL-1alpha promoted COX-2 protein expression in BDECs. Treatment with IL-1alpha promoted PGE2 production from BDECs in a dose-dependent manner. These results indicate that IL-1alpha stimulates PGE2 synthesis largely by inducing BDECs to express COX-2. Because PGE2 stimulates bone resorption, these vascular endothelial cells, as well as osteoblast cells, play important roles in bone remodeling.

Interleukin-1 signaling is dependent on free thiols

Stimulation of the Interleukin-1 receptor type I (IL-1-RI) with IL-1 activates an associated serine/threonine kinase, IRAK, which phosphorylates downstream targets, resulting in NFkappaB activation. The signaling cascade is accompanied by oxidative processes and contains putative targets for redox regulation. Preincubation of the murine T cell line EL-4 and the human umbilical cord vein endothelial cell line ECV 304 with thiol modifying compounds like diamide, menadione or phenylarsine oxide inhibited the IL-1-induced phosphorylation of an endogenous substrate with a molecular mass of 60 kD. In the endothelial cell line, a second target of about 85 kD was phosphorylated after IL-1 stimulation, which was also inhibited by thiol modification. These data suggest that IL-1 signal transduction depends on free thiols which might be targets for redox regulation not only in lymphocytes, but also in endothelial cells.

Interleukin-1 receptor defect in autoimmune NZB mouse brain

Interleukin-1 receptors (IL-1R type I and II) have been characterized in murine nervous structures (hippocampus and frontal cortex), in vascular structures (vessels, choroid plexus), and in the anterior pituitary. Because interleukin-1 (IL-1), injected or induced in the brain, is a powerful regulator of the stress axis and immune functions, it was of interest to investigate IL-1Rs and IL-1 in autoimmune mice. In control mice, bacterial lipopolysaccharide (LPS), administered i.p. or i.c.v., induces a sharp decrease in available brain IL-1 receptors, in spite of a moderate increase in mRNAs for both receptor types. This is concomitant with an increase in IL-1 alpha, beta, and ra mRNA. Ligand production clearly overcomes receptor turnover. In autoimmune mice (NZB and NZB/NZW F1), a strong defect in IL-1R (type I) is demonstrated in the dentate gyrus. This tissue-specific defect cannot be explained by increased occupancy by endogeneous ligands as for LPS-treated mice. The transmission of the defect is Mendelian and suggests the involvement of a single gene. However patterns of IL-1R mRNAs (evaluated by RT-PCR) are similar in NZB and in controls, suggesting a translational or post-translational abnormality. The contribution of this genetic disorder in the development of autoimmunity remains to be clarified. Because the brain IL-1 system sends inhibitory signals towards immune functions, this lack of functional IL-1 binding sites might participate in the disregulations observed in NZB autoimmune mice.

Correlation of serum levels of interleukin-1 family members with disease activity and response to treatment in hairy cell leukemia

Hairy cell leukemia (HCL) is a well-recognized chronic lymphoproliferative disorder of B cell lineage, which may be regulated by growth factors including cytokines and cytokine antagonists. Previous studies have shown a good correlation between circulating soluble interleukin-2 receptor (sIL-2R) levels and disease activity and response to therapy was always associated with a decrease in sIL-2R levels. The interleukin-1 (IL-1) family of agonists and antagonists may also be involved in the regulation of hematopoietic malignancies. In the present study, we evaluated members of the IL-1 family (IL-1beta, IL-1 receptor antagonist (IL-1Ra) and IL-1 soluble receptors Type I and Type II (IL-1sRI and IL-1sRII) in 23 patients with HCL. Patients were classified according to the clinical state of their disease. Most were treated with 2-chloro-2'-deoxyadercosine (2-CDA) and treatment was associated with a significant decrease in the serum levels of sIL-2R, IL-1beta and IL-1sRII in patients achieving a complete or partial response. In contrast to the above, levels of IL-1Ra increased during response to treatment and clinical response to 2-CDA was associated with an increase of 122% in IL-1Ra levels, in parallel with a decrease of 63% in IL-1beta and 47% in IL-1sRII levels. These results suggest that the balance between IL-1beta, IL-2 and their soluble receptors or antagonists may be involved in the pathogenesis and immunoregulation of HCL. Serum levels of these cytokines may therefore be used to monitor therapeutic efficacy of therapy in HCL and to detect any residual disease.

Insulin-like growth factor I affects the intraovarian interleukin-1 system: evidence for suppression of type I interleukin-1 receptor expression and enhancement of secretory phospholipase A2 expression and activity

This study assessed the possibility that the intraovarian insulin-like growth factor I (IGF-I) system interacts with the intraovarian interleukin-1 (IL-1) system, the central role of which has been the subject of increasing attention. To this end, whole ovarian dispersates from immature rats were cultured for 48 h in the absence or presence of IGF-I or IGF-binding protein-3 (IGFBP-3), with or without IL-1beta. Cellular RNA content was subjected to a solution hybridization, RNase protection assay with gel-purified [32P]-UTP-labelled antisense riboprobes for rat IL-1beta, type I IL-1 receptor (IL-1R) and secretory phospholipase A2 (sPLA2). PLA2 activity in conditioned media was assayed by measuring the release of [3H]-labelled palmitic acid from the sn-2 position of [3H]-labelled phosphatidylcholine dipalmitoyl (PCDP) substrate. Treatment with IGF-I resulted in a significant (P< 0.01) decrease in type I IL-1R transcripts (an effect which was reversed by co-treatment with IL-1beta), was without effect on IL-1beta transcripts, and significantly (P < 0.05) increased sPLA2 gene expression (an effect which was further enhanced by co-treatment with IL-1beta). Treatment with IGF-I resulted in a significant increase in extracellular PLA2 activity over untreated control. These observations suggest that IGF-I may down-regulate ovarian IL-1 action by decreasing type I IL-1R gene expression, while up-regulating sPLA2 gene expression and activity. These findings are consistent with a role for IGF-I in suppressing IL-1 actions while promoting the generation of prostaglandins. It is tempting to speculate that IGF-I, an intraovarian regulator concerned with promoting folliculogenesis, may be also entwined with priming the prostaglandin-producing potential in anticipation of subsequent ovulation.

Interleukin-1 (IL-1) receptor type I mediates anorexia but not adipsia induced by centrally administered IL-1beta

IL-1beta induces anorexia and adipsia. Here, we report that intracerebroventricular (ICV) pretreatment with an antisense (but not sense) phosphothio-oligodeoxynucleotide to the IL-1 receptor type I (IL-1RI, 1.28 microg or 239 pmol twice daily for 3.5 days before IL-1beta plus antisense) inhibits the anorexia, but not the adipsia induced by the ICV administration of 2.0 ng IL-1beta/rat (a dose that yields estimated pathophysiological concentrations in the cerebrospinal fluid). The mean 2 h food intake decrease in response to IL-1beta was 5.6% (n = 10) in the antisense- and 43% in the sense (n = 9)-treated groups; the mean 2 h water intake decrease was 40% in the antisense- and 39% in the sense-treated groups. The intraperitoneal administration of IL-1RI antisense, in doses equivalent to those administered centrally, had no effect on the anorexic effect induced by ICV administered IL-1beta; this indicates a direct action in the central nervous system. The results suggest that: i) IL-1RI is involved in the short-term anorexigenic, but not the adipsogenic effect induced by centrally administered IL-1beta; and ii) the approach presented using antisense strategies is applicable to study the molecular basis of IL-1 mediated behaviors.

In vivo immunomodulatory effects of clozapine in schizophrenia

Recently, there have been some reports that schizophrenia is accompanied by an immune-inflammatory response, characterized by increased secretion of interleukin-6 (IL-6), soluble IL-2 receptor (sIL-2) and lower plasma levels of CC16 (Clara cell protein), an endogenous anti-cytokine. It was shown that clozapine, an atypical antipsychotic drug, may increase the plasma levels of sIL-2R and pro-inflammatory cytokines. This study was carried out in order to examine serum IL-6, IL-6R, CC16, IL-1R antagonist (IL-1RA), transferrin receptor (TfR) and sCD8 antigen, both before and after treatment with clozapine in schizophrenic subjects versus normal controls. Schizophrenic patients showed significantly higher plasma IL-6R and IL-1RA and lower plasma CC16 than normal controls. Treatment with clozapine significantly increased plasma sCD8, IL-6, CC16 and IL-1RA concentrations. The clozapine-induced increments in plasma IL-6 and CC16 appeared during the first 2 weeks of treatment, whereas the increases in plasma sCD8 and IL-1RA appeared after 5 weeks. Clozapine appears to have complex in vivo immunomodulatory effects.

Receptor induction regulates the synergistic effects of substance P with IL-1 and platelet-derived growth factor on the proliferation of bone marrow fibroblasts

The neuropeptide substance P (SP) stimulates CFU in bone marrow (BM) cultures. Although the methylcellulose matrix used in these assays does not provide an appropriate substratum to support adherent-dependent cells, we have observed that cultures containing optimal SP (10(-8)-10(-10) M) develop confluent areas of reticular/fibroblastoid-like cells with CFUs predominantly localized within their vicinity. Characterization (cytochemical and immunofluorescence) of the reticular/fibroblastoid-like cells indicated that they were fibroblasts, the major constituent of the BM stroma. Hemopoietic effects by SP are mediated by the stroma that expresses SP receptors. We studied the effects of SP (10(-7)-10(-11) M) with suboptimal platelet-derived growth factor-BB (PDGF-BB; 5 ng/ml) and IL-1alpha (2 ng/ml), two fibrogenic cytokines, and also hemopoietic regulators. SP by itself and in synergy with either cytokine induced fibroblast proliferation. At optimum SP, IL-1alpha induced 1.6 times the proliferation of PDGF-BB (87 +/- 7 vs 55 +/- 5; n = 12; p < 0.05). The effects of SP were blunted by a specific neurokinin-1 antagonist. Scatchard analysis indicated that SP binds to BM fibroblasts with an approximate Kd of 5 nM. SP induced steady state mRNA for IL-1 receptor IL-1RI and PDGF-BB (PDGF-AR, PDGF-BR) receptors by 7.5-, 6.2-, and 10.5-fold, respectively. Their up-regulation may be partly responsible for the synergistic effects of SP and their ligands. Induction (3-fold) of neurokinin-1 mRNA by IL-1alpha compared with no induction by PDGF-BB may explain the preferred synergism between SP and IL-1alpha. This study indicates that induction of SP, IL-1alpha, and PDGF-BB receptors is important to their synergistic effects on BM fibroblast proliferation. These results bring new insights into stroma-mediated hemopoietic regulation.

The afferent discharges from sensors for interleukin 1 beta in the hepatoportal system in the anesthetized rat

The effect of intraportal administrations of interleukin 1 beta (IL-1 beta) on the afferent activity of the hepatic branch of the vagus nerve was observed in urethane anesthetized rats. An intraportal injection of IL-1 beta in doses of 10 pg and 100 pg per animal (300-400 g body wt.) resulted in dose-dependent increase in the afferent activity, which lasted about 70-100 min. Further, intraportal injection of IL-1 beta (100 pg) induced reflex activation of efferent activity of the splenic (sympathetic) nerve and vagal thymic nerve. This reflex activation was not observed in hepatic vagotomized rat and after an administration of the same dose of IL-1 beta into the systemic vein in normal rat. The results suggest the existence of sensors for IL-1 beta which send information on IL-1 beta in the portal venous blood to the central nervous system through the hepatic branch of the vagus nerve and play some role in reflex regulation of immune function.

An approach to study molecular mechanisms involved in cytokine-induced anorexia

Cytokines are released during pathophysiological processes. Cytokines (e.g., interleukin-1 beta or IL-1 beta) induce neurological manifestations including anorexia. Here, we show an integrative approach to investigate the cellular and molecular basis of cytokine-induced anorexia. In this approach: (1) the chronic intracerebroventricular (icv) microinfusion (via osmotic minipumps) of cytokines, at doses that will yield estimated pathophysiological concentrations reported in the cerebrospinal fluid, is used. (2) General and computerized behavioral monitoring characterizes the microstructure of behavioral modifications induced by a cytokine, and the time course for cytokine action. (3) Brain regions and subregions (nuclei/areas) from animals exhibiting significant anorexia in response to cytokine(s) are dissected, and RNA and protein are isolated. (4) The profile of cytokine subsystems (ligands, receptors, endogenous inhibitors; for example, IL-1 alpha and beta, IL-1 receptor types I and II, and IL-1 receptor antagonist) is characterized in the same brain samples with polymerase chain reaction, sensitive RNase protection assays and immunoblots. (5) The relationship between changes in cytokine subsystems at the molecular level and cytokine-induced anorexia within an animal is determined, and the general profile is analyzed with statistical methods. This approach is also pertinent to study neurotransmitter and neuropeptide profiles, and cytokine-cytokine, cytokine-neuropeptide and cytokine-neurotransmitter interactions in vivo. The results show that this integrative and novel strategy can be used to study the molecular basis of anorexia and other neurological manifestations (e.g., fever, sleep changes) induced by cytokines.

Hormonal regulation of serum and endometrial IL-1 alpha, IL-1 beta and IL-1ra: IL-1 endometrial microenvironment of the human embryo at the apposition phase under physiological and supraphysiological steroid level conditions

We have investigated serum and intracavitary levels of IL-1 alpha, IL-1 beta and IL-1ra from agonadal women undergoing mock cycles (n = 20) of oocyte donation as a clinical model of controlled hormonal stimulation. Further, we compared the intracavitary IL-1 alpha, IL-1 beta and IL-1ra levels in the microenvironment of the human embryo at the apposition phase, day 5 after progesterone (P) administration using two different clinical models: oocyte donation (n = 20) which provides physiological steroid levels and a higher implantation rate per embryo, and in vitro fertilization (n = 6) with supraphysiological hormonal levels and a lower implantation rate.

[Acute pancreatitis: inflammatory response of the body]

The author reviews the most important data related with the pathogenesis of pancreatitis acuta, the pathological characteristics, the clinical development of the disease, the more frequent complications are summarized. Within this scope the evolutionary mechanisms of the organ damages are discussed, the diagnostic and prognostic relations are delineated, too. Particular attention is paid to the development and regulation of the defending, preventing reactions of the organisms connected with pancreatitis acuta. The process of leukocyte emigration into the tissue being shortly summarized, the acute phase reaction of the organism and the pathophysiological, clinical significance of the acute phase reactants are likewise presented. The author deals distinctly with the physiological, pathophysiological functions of alpha 2-macroglobulin and with its significance in pancreatitis acuta. The therapeutic outlooks are in a few words touched upon. The acute phase reaction of the organism is inserted in the framework of the possible types of the protecting, preventing responses of the organism.

Interleukin-1 receptor accessory protein transcripts in the brain and spleen: kinetics after peripheral administration of bacterial lipopolysaccharide in mice

Receptors for IL-1, type I (IL-1R1) and type II (IL-1R2), have been characterized by pharmacological and molecular techniques in the mouse brain. High densities are mainly found in the cortex, dentate gyrus and choroid plexus. It was therefore of interest to investigate the expression of mRNA IL-1 receptor accessory protein (IL-1R AcP), which is a part of the IL-1 receptor complex and has been shown to interact specifically with IL-1R1. IL-1R AcP transcripts were detected under basal conditions following RT-PCR amplification in the mouse brain, as well as in the pituitary, spleen, adrenal and liver. IL-1R AcP transcripts were found in higher amounts than IL-1R1 transcripts in all tissues except the spleen, where their expression was minor. Following bacterial lipopolysaccharide (LPS) stimulation (3-48 h), IL-1R AcP transcripts were not changed in the brain, while IL-1R1 transcripts were increased for 3-6 h. In the spleen, a slight increase in IL-1R AcP and IL-1R1 was observed during the first hours following LPS stimulation. In conclusion, IL-1R AcP mRNA is expressed in the brain and in other tissues where IL-1R1 transcripts are found. However, the regulation of its expression is distinct from IL-1R1. The high level of expression and the lack of regulation of IL-1R AcP transcripts in the brain under inflammatory conditions suggest that the protein might be constitutively expressed in excess.

An investigation of the effects of heparin, low molecular weight heparin, protamine, and fentanyl on the balance of pro- and anti-inflammatory cytokines in in-vitro monocyte cultures

We report a study conducted to determine if drugs given peri-operatively during cardiac surgery could themselves modulate the balance of pro- and anti-inflammatory cytokines. We determined the cytokine response of 10 separate in vitro monocyte cultures to the administration of drugs at concentrations used during cardiac 'surgery:fentanyl (25 ng.ml-1), heparin 2.5 i.u.ml-1, heparin with an equal concentration of protamine, and enoxaparin 2.5 i.u.ml-1. Fentanyl, heparin and low molecular weight heparin (enoxaparin) led to increased tumour necrosis factor alpha but this did not reach statistical significance. Tumour necrosis factor soluble receptor 1 and 2 was not elevated. Interleukin-1 beta was increased by heparin (p < 0.05), whereas interleukin-1 receptor antagonist was increased by fentanyl (p < 0.05). Protamine blocked the heparin-induced increase in tumour necrosis factor alpha and interleukin-1 beta. These data raise the possibility that endogenous and exogenously administered opioids may be partly contributing to the interleukin-1 receptor antagonist response seen during major surgery.

Detection and in vivo hormonal regulation of rat ovarian type I and type II interleukin-I receptor mRNAs: increased expression during the periovulatory period

OBJECTIVE

To study the expression, localization, and in vivo hormonal regulation of type I and type II interleukin-1 (IL-1) receptors in the rat ovary.

METHODS

Segments of the cDNAs for rat type I and type II IL-1 receptors were cloned and used as probes in RNase protection assays and in situ hybridization. Tissues obtained from immature rats and hormonally treated rat ovaries were examined.

RESULTS

Type I IL-1 receptor (IL-1R(1)) was ubiquitously expressed in rat tissues, including granulosa cells prepared from immature ovaries, whereas type II IL-1 receptor (IL-1R(2)) expression was restricted to macrophages, thymus, and lung. Hypophysectomy and subsequent treatment with FSH and/or diethylstilbestrol did not alter significantly the abundance of IL-1R(1) transcripts in the whole ovary. However, the relative amount of ovarian IL-1R(1) transcripts increased 7.3-fold 6 hours after the administration of hCG to pregnant mare serum gonadotropin-primed immature rats. During this time, IL-1R(1) mRNA was localized primarily in the granulosa cells. The increased expression of IL-1R(1) persisted 24 hours after hCG administration but declined to baseline by 48 hours. Ovarian expression of IL-1R(2) mRNA was observed only before ovulation in amounts that were approximately 70-fold lower than IL-1R(1).

CONCLUSION

The increased intraovarian expression of IL-1R(1) in granulosa cells during the periovulatory period implies that this cell type has a heightened receptivity to IL-1 and provides further indirect evidence that this cytokine is involved in the ovulatory process.