Human intestinal epithelial cells secrete interleukin-1 receptor antagonist and interleukin-8 but not interleukin-1 or interleukin-6

BACKGROUND

There is growing evidence that intestinal epithelial cells (IECs) are involved in the mucosal immune system.

AIM

To assess the pattern of cytokines secreted by IECs and lamina propria mononuclear cells (LPMNCs). To achieve this, the expression and secretion of interleukin (IL)-1, IL-1 receptor antagonist (IL-1ra), IL-6, and IL-8 in human primary colonic and ileal IECs and LPMNCs from the same patient were studied.

METHODS

IECs and LPMNCs were isolated from surgical specimens or endoscopic biopsy samples. mRNA expression was investigated by northern blot analysis. Secretion of IL-1beta, IL-6, IL-8, and IL-1ra was measured by enzyme linked immunosorbent assay.

RESULTS

IL-1ra mRNA levels were higher in IECs than in LPMNCs in all probands. IL-8 mRNA was only present in low amounts in the IECs from two controls. In none of the specimens were IL-1beta and IL-6 mRNA present in IECs. Transcripts encoding IL-1beta, IL-1ra, IL-6, and IL-8 were identified in LPMNC preparations of all specimens. IECs from normal mucosa produced no detectable amounts of IL-1beta or IL-6, whereas LPMNCs did. IECs secreted some IL-8 (65 (9) pg/10(5) cells) but significantly more was generated by LPMNCs (408 (43) pg/10(5) cells, p<0.0001). However, IECs secreted more IL-1ra than did LPMNCs (120 (12) v 94 (11) pg/10(5) cells). In acute inflammation, IEC IL-1ra secretion was significantly increased. A correlation between secreted IL-1ra and the macroscopical degree of inflammation was found in Crohn's disease (r = 0.64, p<0.0001, n = 36) and ulcerative colitis (r = 0. 76, p<0.0001, n = 24).

CONCLUSIONS

IECs from normal mucosa express and secrete IL-1ra and low amounts of IL-8, but no IL-1 or IL-6. In inflamed mucosa the secretion of IL-1ra by IECs is slightly increased but may be not sufficient to antagonise the greatly increased production of proinflammatory cytokines by LPMNCs and the IECs themselves.

Polarized distribution of interleukin-1 receptors and their role in regulation of serotonin transporter in placenta

We investigated the expression of interleukin-1 (IL-1) receptors and their involvement in the regulation of the serotonin transporter gene expression in human placenta. IL-1beta is an activator of the serotonin transporter gene expression in JAR human placental choriocarcinoma cells as demonstrated by an increase in the steady-state levels of the transporter mRNA and in serotonin transport activity. This activation is blocked by IL-1 receptor antagonist. Genistein also blocks the effect of IL-1beta, indicating involvement of tyrosine phosphorylation in the process. Treatment of JAR cells with IL-1beta activates mitogen-activated protein kinases and nuclear factor-kappaB. The nuclear factor-kappaB that is responsive to IL-1beta in these cells is the p65 homodimer. Northern blot analysis and reverse transcription-polymerase chain reaction revealed that JAR cells and human placenta express type I and type II IL-1 receptors. The binding sites for (125)I-IL-1beta are localized predominantly in the maternal-facing brush border membrane of the syncytiotrophoblast. These results show that IL-1 in the maternal circulation is likely to play a critical role in the regulation of the serotonin transporter gene expression in the placenta.

Arterial inflammation in mice lacking the interleukin 1 receptor antagonist gene

Branch points and flexures in the high pressure arterial system have long been recognized as sites of unusually high turbulence and consequent stress in humans are foci for atherosclerotic lesions. We show that mice that are homozygous for a null mutation in the gene encoding an endogenous antiinflammatory cytokine, interleukin 1 receptor antagonist (IL-1ra), develop lethal arterial inflammation involving branch points and flexures of the aorta and its primary and secondary branches. We observe massive transmural infiltration of neutrophils, macrophages, and CD4(+) T cells. Animals appear to die from vessel wall collapse, stenosis, and organ infarction or from hemorrhage from ruptured aneurysms. Heterozygotes do not die from arteritis within a year of birth but do develop small lesions, which suggests that a reduced level of IL-1ra is insufficient to fully control inflammation in arteries. Our results demonstrate a surprisingly specific role for IL-1ra in the control of spontaneous inflammation in constitutively stressed artery walls, suggesting that expression of IL-1 is likely to have a significant role in signaling artery wall damage.

IL-1beta increases intracellular calcium through an IL-1 type 1 receptor mediated mechanism in C6 astrocytic cells

Interleukin-1beta (IL-1beta) is a cytokine that regulates a variety of biological processes. In addition to its traditional role in the immune system, IL-1beta plays an integral role in neural-immune and developmental processes in the nervous system. The pleiotropic ability of IL-1beta may be due to the activation of different signal transduction mechanisms in specific cell types or under certain cellular conditions. We have previously demonstrated that IL- regulates healing and repair in the developing, mammalian nervous system. In the damaged perinatal mouse brain, IL-1beta is expressed in astrocytes that change from a stellate to a spindle-shaped morphology. The spindle-shaped astrocytes enclose the wound, separating the healthy from damaged neural tissue. The shape change and subsequent repair processes are IL-1beta activity-dependent, acting through the IL-1 type 1 receptor (IL-1R1), as co-application of the IL-1type 1 receptor antagonist protein (IL-1ra) blocks IL-1beta induced effects. In the C6 astrocytic cell line, IL-1beta induced similar shape changes and upregulated expression of the cytoskeletal protein, glial fibrillary acidic protein (GFAP). Since cytoskeletal changes, as well as specific signal transduction mechanisms, are associated with increases in intracellular calcium ([Ca2+]i), studies were carried out to determine if increases in [Ca2+]i induced by IL-1beta occurred through activation of the IL-1R1 in C6 cells. Cells were treated with IL-1beta and/or IL-1ra, followed by measurement of relative changes in [Ca2+]i using fura-2 fluorescence imaging methods. IL-1beta increased [Ca2+]i levels in a dose and time dependent manner. Treatment with IL-1ra blocked IL-1beta induced increases in [Ca2+]i, indicating that IL-1beta acts through the IL-1R1. Immunocytochemistry experiments showed that untreated C6 cells normally express IL-1beta, IL-1ra, and IL-1RI. Thus, IL-1 system molecules may play a role in normal C6 astrocyte physiology.

Interleukin-1beta (IL-1beta) is a modulator of human luteal cell steroidogenesis: localization of the IL type I system in the corpus luteum

The present investigation examined the effect of interleukin-1beta (IL-1beta) on progesterone production by human luteal cells and the expression and localization of the IL-1 system in the human corpus luteum (CL). Luteal cells were isolated from corpora lutea collected throughout the luteal phase. After dispersion, luteal cells were treated with a panel of monoclonal antibodies directed to leukocyte-specific molecules. The leukocytes were isolated with immunomagnetic beads. Leukocyte-free luteal cells exhibited greater steroidogenic responsiveness to hCG toward the end of the luteal phase. The treatment of mixed luteal cells (total luteal cells) with IL-1beta inhibited by 60% hCG-stimulated progesterone production. Interestingly, the treatment of leukocyte-free luteal cells with IL-1beta did not affect progesterone production. In addition, the treatment of mixed luteal cells with monoclonal antibodies against IL-1 receptor type I (IL-1RtI) resulted in a 2.5-fold increase in the hCG-supported progesterone production. IL-1RtI and IL-1 receptor antagonist were localized by immunohistochemistry in both somatic and immune cells of the CL. Flow cytometric analysis indicated that both nonleukocyte luteal cells and leukocyte-luteal cells exhibited IL-1Rt-I positive cells, representing 56% and 31% of the total luteal cells, respectively. However, 13% of nonleukocyte luteal cells did not express IL-1Rt-I. Northern analysis demonstrated the presence of the 5.1-kb IL-1RtI messenger ribonucleic acid transcript in CL of different ages. RT-PCR indicated that both leukocyte-free luteal cells and luteal leukocytes express IL-1RtI messenger ribonucleic acid. We conclude that 1) luteal leukocytes have an inhibitory effect on hCG-stimulated progesterone production; 2) IL-1beta inhibits hCG-stimulated progesterone production only in mixed luteal cell cultures, indicating that leukocytes mediate the effect; 3) the somatic and immune cells of the CL are sites of action and expression of the IL-1 system; and 4) interaction between the steroidogenic and immune cells of the CL suggests a functional intraovarian role for IL-1beta in CL physiology.

A comprehensive guide for the recognition and classification of distinct stages of hair follicle morphogenesis

Numerous spontaneous and experimentally induced mouse mutations develop a hair phenotype, which is often associated with more or less discrete abnormalities in hair follicle development. In order to recognize these, it is critically important to be able to determine and to classify accurately the major stages of normal murine hair follicle morphogenesis. As an aid, we propose a pragmatic and comprehensive guide, modified after previous suggestions by Hardy, and provide a list of easily recognizable classification criteria, illustrated by representative micrographs. Basic and more advanced criteria are distinguished, the former being applicable to all mouse strains and requiring only simple histologic stains (hematoxylin and eosin, Giemsa, periodic acid Schiff, alkaline phosphatase activity), the latter serving as auxiliary criteria, which require a pigmented mouse strain (like C57BL/6J) or immunohistochemistry (interleukin-1 receptor type I, transforming growth factor-beta receptor type II). In addition, we present simplified, computer-generated schematic drawings for the standardized recording and reporting of gene and antigen expression patterns during hair follicle development. This classification aid serves as a basic introduction into the field of hair follicle morphogenesis, aims at standardizing the presentation of related hair research data, and should become a useful tool when screening new mouse mutants for discrete abnormalities of hair follicle morphogenesis (compared with the respective wild type) in a highly reproducible, easily applicable, and quantifiable manner.

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

Several lines of evidence suggest that interleukin-1 (IL-1) acts directly on the central nervous system, probably within the hypothalamus, causing effects such as fever, activation of the immune response and sickness behaviour. IL-1 has also been shown to be involved in the aetiology of several neuronal diseases, including neurodegeneration, stroke and Alzheimer's disease. However, the question as to whether the full-length type I IL-1 receptor (IL-1RI) is expressed in the human hypothalamus has yet to be addressed. Using the polymerase chain reaction, we cloned a full-length cDNA encoding the human hypothalamic IL-1RI from human hypothalamic cDNA. The DNA sequence of the human hypothalamic receptor was identical to that of the human fibroblast IL-1RI. The IL-1RI receptor protein was detected in astrocytes of normal human hypothalamic brain sections using immunocytochemical techniques. To ascertain that the cloned receptor was functional, Chinese hamster ovary (CHO) cells were transfected with a plasmid vector containing the IL-1RI coding region. IL-1RI-mediated-signal transduction was assessed by microphysiometry and activation of p38 MAP (mitogen-activated protein) kinase. We report the first demonstration that both the type I IL-1 transcript and the protein are expressed in the human hypothalamus. The receptor was expressed in a stable CHO cell line, providing a tool with which to embark on a thorough analysis of the signalling mechanisms mediated by IL-1 via this receptor.

Complex interactions between sex steroids and cytokines in the human pregnant myometrium: evidence for an autocrine signaling system at term

Little is known about the mechanisms controlling the expression of key proteins that regulate excitability and contractility in the human myometrium at term. However, evidence is accumulating to suggest that the cytokine transforming growth factor (TGF)beta may play a central role. TGFbeta1 and TGFbeta receptors are present in the myometrial cells, indicative of an autocrine signaling system. Furthermore, the levels of TGFbeta1 and the expression of its receptors increase in the myometrium at term suggesting that they are, in turn, regulated and form part of a physiological cascade of events involving a number of autocrine signaling associated proteins. The present experiments were done to identify factors that regulate the expression of TGFbeta1 and TGFbeta receptors and may form other elements of this cascade. Because IL-1 and IL-8 are found in the myometrium at term and have been implicated in the etiology in premature labor we focus on this cytokines. Receptors for IL-1 and IL-8 were detected in the myometrial cells. Using Western blot analysis, the levels of expression were found to vary. The expression of IL-1 receptor type I was highest in the nonpregnant tissue with lower levels in nonlaboring myometrium with a further reduction in the spontaneously laboring tissue. In contrast, the expression of IL-8 receptor type B was highest in the pregnant nonlaboring tissue with a lower level in the spontaneously laboring tissue. Using an in vitro model, TGFbeta1 and TGFbeta receptor expression was up-regulated by IL-8, IL-1, and TGFbeta1 itself. However, IL-8 receptor expression was decreased by IL-8 and TGFbeta1. This suggests that in a cascade IL-8 would feed forward to promote the TGFbeta system, whereas TGFbeta1 feeds back to inhibit responsiveness to IL-8. Estrogen and progesterone increased the release of TGFbeta1. However, at high concentrations, estrogen and progesterone (100 nM 17beta-estradiol or 200 nM progesterone) decreased the level of TGFbeta receptor expression. Thus, the progressive rise of steroid levels in vivo might account for the observed changes in TGFbeta1 and TGFbeta receptor expression in vivo. Taken together, these observations support the idea that there is a cascade of autocrine signals that may play a major role in the physiological processes preparing the myometrium for parturition at term.

Gene expressions of antiinflammatory mediators in THR retrieved interfacial membranes

We investigated gene expression of antiinflammatory mediators in the interfacial membranes retrieved at hip revision arthroplasty using reverse transcription-polymerase chain reaction (RT-PCR). Levels of RT-PCR products were compared with those of synovial tissue from patients with osteoarthrosis or rheumatoid arthritis. Antiinflammatory mediators such as type II interleukin (IL)-1 receptor, IL-4, IL-10, IL-1 receptor antagonist, and transforming growth factor-beta 1 (TGF-beta 1) were expressed in the interfacial membrane. In interfacial tissue, the level of IL-10 was lower, but that of the IL-1 receptor antagonist higher than in diseased synovial tissue.

Co-localization of interleukin-1 receptor type I and interleukin-1 receptor antagonist with vasopressin in magnocellular neurons of the paraventricular and supraoptic nuclei of the rat hypothalamus

Interleukin-1 receptor type I and interleukin-1 receptor antagonist were found in magnocellular neurons of the paraventricular and supraoptic nuclei of the rat hypothalamus by immunohistochemical detection. Double-labelling experiments revealed that both proteins occurred in vasopressin-containing neurons. A similar distribution pattern was observed in a group of vasopressin-positive accessory magnocellular neurons. Axons emanating from the interleukin-1 receptor type I- and interleukin-1 receptor antagonist-immunoreactive neuronal cell bodies could be seen within the hypothalamic nuclei, and varicosities expressing interleukin-1 receptor antagonist immunoreactivity were observed in the internal zone of the median eminence, as well as in the hypothalamo-pituitary projection. The co-localization of interleukin-1 receptor type I with vasopressin is in agreement with findings that interleukin-1 has a stimulatory effect on vasopressin synthesis and release. The hypothalamic neurons may serve as a source of interleukin-1 receptor antagonist to balance the effects of interleukin-1.

Expression and localization of p80 and p68 interleukin-1 receptor proteins in the brain of adult mice

The biological effects of interleukin-1 (IL-1) are mediated by two distinct receptors, the p80 type I IL-1 and p68 type II IL-1 receptor proteins (IL-1RI and IL-1RII, respectively), both of which have been recently co-localized to the growth hormone synthesizing cells of the adenohypophysis. Previous studies have shown that IL-1 can bind to specific structures in the central nervous system, but the distribution of IL-1RI and IL-1RII proteins in the adult mouse brain has not been reported. Here we have used immunohistochemistry to study the expression, distribution and cellular localization of both isoforms of the IL-1 receptor proteins in the adult mouse brain. Using a combination of processing techniques (AMeX fixation and cryosectioning), we have immunolabeled brain sections for each isoform of the IL-1R. Both isoforms are expressed in the CNS, particularly in neuronal soma of the granular layer of the dentate gyrus and pyramidal cells of fields CA1-CA4 of Ammon's horn of the hippocampus, in epithelial cells of the choroid plexus and ependymal layer, and in neuronal soma of Purkinje cells of the cerebellum. The IL-1RII isoform, but not IL-1RI, is expressed in specific neuronal soma and proximal cell processes of neurons of the paraventricular gray matter of the hypothalamus. These immunohistochemical data directly demonstrate the neuronal expression of both IL-1R proteins in situ. The distribution and cellular localization of IL-1R proteins in the CNS provide a molecular basis for understanding reciprocal interactions between the immune system and the brain.

Distribution of interleukin-1 receptors in term human fetal membranes and decidua

Interleukin-1 (IL-1) is a dimorphic cytokine that acts on target cells through high-affinity receptors, type I and type II. It has been implicated in the onset of term and preterm labour with associated intrauterine infection. To define better the potential action of this cytokine in the human fetal membranes and decidua, the objective of this study was to define the type(s) of IL-1 receptors present in the tissues at term, examine the tissue and cellular distribution of the receptor(s) and determine if there were any changes in their expression or distribution with the onset of labour. Tissues were obtained following elective caesarean section (n=12) or normal labour delivery (n=11). Paraffin embedded and frozen sections were examined by immunohistochemistry and in situ hybridization for evidence of the type I and type II receptors and their corresponding mRNAs. In all tissues studied the type I receptor was localized mainly to the decidua and the type II receptor was localized to the decidua and scattered cells in the amnion-chorion mesenchymal layer. In situ hybridization localized type I receptor mRNAs and type II receptor mRNAs to the decidua. The type I and type II receptor protein in the decidua showed a similar pattern of staining as that found for CD-68, a macrophage marker. The pattern of receptor expression and distribution was unrelated to the mode of delivery. No evidence for the presence of the type I or type II receptor or their mRNAs in the amnion epithelial cells or chorion laeve trophoblast was found.

Characteristics and regulation of the expression on interleukin 1 receptors by murine Langerhans cells and keratinocytes

There is increasing evidence that interleukin 1beta (IL-1beta), a product in murine epidermis of Langerhans cells (LC) exclusively, contributes to the initiation and regulation of LC migration in response to skin sensitization. The hypothesis is that IL-1beta induces the production by keratinocytes of tumour necrosis factor alpha (TNF-alpha) which acts in a paracrine fashion on LC to provide one signal for migration. In addition, it is believed that IL-1beta acts in an autocrine fashion on LC to provide a second, TNF-alpha-independent, signal for the initiation of this response. The viability of this hypothesis is dependent upon the availability of appropriate membrane receptors. We describe therefore experiments designed to investigate the IL-1 receptor (IL-1R) status of keratinocytes, LC and lymph node dendritic cells (DC). Flow cytometric analyses of epidermal cell suspensions revealed at least 60% of LC positive for the type I IL-1R (IL-1RI). In contrast, only a small proportion of keratinocytes displayed surface IL-1RI, although high intracellular expression of this receptor could be detected either by flow cytometric analysis of cells permeabilized with saponin or by immunofluorescence microscopy. Expression of the type II IL-1R (IL-1RII) was detected at relatively low levels on both LC and keratinocytes. Interestingly, DC isolated from the lymph nodes of sensitized mice displayed upregulated expression of IL-1RI and lower levels of IL-1RII compared to LC. The conclusion drawn is that the IL-1R phenotype of LC and keratinocytes under resting conditions is consistent with the proposed contribution of IL-1beta to LC migration. Furthermore, the regulation of IL-1R expression by epidermal cells and DC will undoubtedly influence the development of cutaneous immune responses.

Measurement of cytokines in the cavernous sinus plasma from patients with Cushing's disease

In order to know more about the in vivo secretion of various cytokines from the human pituitary, this study measured the concentrations of interleukin (IL)-1alpha, IL-1beta, IL-2, IL-6, tumor necrosis factor-alpha and IL-1 receptor antagonist (ra) in both the peripheral blood and the cavernous sinus (CS) plasma from six patients with Cushing's disease before and after an intravenous bolus injection of human corticotropin-releasing hormone (CRH, 100 microg). As a routine procedure for the diagnosis of Cushing's disease, adrenocorticotropin (ACTH) levels were also determined in the same samples. In four of the six patients, unstimulated levels of IL-1ra in the CS ipsilateral to the ACTH-secreting adenoma were higher than those in the peripheral blood, with a ratio of > or = 1.5:1, even though CRH was without effect on the cytokine's concentration in the CS. In contrast, no consistent data were obtained for any of the remaining five cytokines. These results demonstrate for the first time that the in vivo release of IL-1ra is detectable in at least some corticotroph adenomas, and also suggest a possible role of the cytokine in physiological and pathophysiological processes occurring in the human pituitary.

Tumor necrosis factor and interleukin-1 inhibitors as markers of disease activity of tuberculosis

Serum concentrations of tumor necrosis factor-alpha (TNF), interleukin (IL)-1beta, and their circulating inhibitors soluble TNF receptor type I (sTNFRI), type II (sTNFRII), IL-1 receptor antagonist (IL-1ra), and soluble IL-1 receptor type II (sIL-1RII) were measured for 123 patients with tuberculosis (TB) in various stages of disease, in persons who had been in close contact with patients with contagious pulmonary TB, and in healthy controls. Levels of sTNFRI, sTNFRII, and IL-1ra, but not of sIL-1RII, were elevated in patients with active TB compared with contacts and controls and declined during treatment. The concentrations of these mediators did not differ between patients with pulmonary and extrapulmonary TB. The levels of sTNFRI and IL-1ra were higher in patients with fever and anorexia. Neither TNF nor IL-beta was detectable. We conclude that serum concentrations of sTNFRs I and II and IL-1ra may serve as markers of disease activity of TB. Sequential measurements of these cytokine inhibitors may be useful in the monitoring of antituberculous therapy.

Clusters of perifollicular macrophages in normal murine skin: physiological degeneration of selected hair follicles by programmed organ deletion

In back skin sections from adolescent C57BL/6 mice, regularly distributed, perifollicular inflammatory cell clusters (PICC) were found located around the distal noncycling portion of about 2% of all hair follicles examined. The PICC and the affected hair follicles were characterized during spontaneously developed or induced hair cycle stages, using antibodies against MHC Class II, F4/80, ER-MP23, NLDC 145, CD4, CD8, gammadeltaTCR, IL-1 receptor, and ICAM-1. PICC consisted predominantly of macrophages (MAC), accompanied by a few CD4+ cells, whereas gammadeltaTCR+ and CD8+ cells were absent. During anagen and catagen, some of the PICC+ hair follicles showed variable degenerative phenomena reminiscent of scarring alopecia: thickened basement membrane, ectopic MHC II expression, MAC infiltration into the follicle epithelium, and signs of keratinocyte apoptosis. Loss of distal outer root sheath keratinocytes was detected in 10% of PICC+ hair follicles (0.2% of all hair follicles). Because PICC were located in the vicinity of the bulge region, MAC-dependent damage to follicle stem cells might eventually lead to follicle degeneration. These perifollicular MAC clusters around selected hair follicles may indicate the existence of a physiological program of MAC-dependent controlled follicle degeneration by which damaged or malfunctioning follicles are removed by programmed organ deletion (POD).

Global forebrain ischemia results in differential cellular expression of interleukin-1beta (IL-1beta) and its receptor at mRNA and protein level

The mRNA expression of the proinflammatory cytokine interleukin-1beta (IL-1beta) has been shown to be induced in neural elements during ischemia. It is not clear which cells generate the IL-1beta mRNA and eventually synthesize IL-1 protein and which cells respond to this signaling by producing IL-1 receptors during ischemia. To clarify this question, rats were subjected to global ischemia by bilateral carotid occlusion and hypotension for 20 minutes, followed by reperfusion for 2 hours (n = 7), 8 hours (n = 7), or 24 hours (n = 7). Cryostat sections were hybridized using antisense oligonucleotide probes (30 dimer). Multiple cell markers were used in immunohistochemical staining to identify the cells expressing IL-1beta and IL-1R protein. The sham animals (n = 5) showed no or only a weak expression of IL-1R or IL-1beta mRNA. The number of IL-1beta mRNA-expressing cells was significantly increased by 2 hours of reperfusion in several brain areas including cortex (12-fold compared with sham) and caudate-putamen (14-fold), and was maximally increased in most hippocampal regions by 8 hours of reperfusion (mean +/- SD of positive cells/field versus sham equivalent being 37.9 +/- 12.3 versus 4.0 +/- 3.3; 30.6 +/- 9.0 versus 3.1 +/- 2.3; 41.3 +/- 17.5 versus 2.9 +/- 1.9; in CA1; CA2; CA3/CA4 regions of the hippocampus, respectively). IL-1beta mRNA signal was also intensified in the white matter areas. Changes in IL-1R mRNA were seen in the hippocampus (after 2 hours CA1: 16-fold; CA2: 17-fold; DG: 24-fold increase; and CA3/CA4: 10-fold increase after 8 hours), and the expression was prolonged especially in CA1 and CA2 regions up to 24 hours of reperfusion. The major cellular source of IL-1beta protein was glia (astrocytes, oligodendrocytes, microglia, and scattered perivascular macrophages/monocytes), while neurons and sporadic microvascular endothelia showed IL-1R immunoreactivity. The data suggest that neurons in discrete areas vulnerable for selective neuronal death, and possibly the vascular endothelium, are target cells for ischemia-induced glial IL-1beta production.

Gingival crevicular interleukin-1 and interleukin-1 receptor antagonist levels in periodontally healthy and diseased sites

Interleukin-1 (IL-1) molecules, IL-1 alpha and IL-1 beta are cytokines involved in the acute-phase response against infection and in the pathogenesis of periodontal destruction. Administration of exogenous IL-1 receptor antagonist (IL-1ra) is effective in reducing the inflammatory reactions mediated by IL-1. However, the relationship between these three naturally occurring IL-1 molecules and periodontal diseases has been poorly characterized. We investigated the correlation of gingival crevicular IL-1 molecules and the clinical status of patients with different severities of periodontitis. IL-1 alpha, IL-1 beta, IL-1ra and the total IL-1/IL-1ra ratio (IL-1 activity index; IL-1AI) were measured in 75 gingival crevicular fluid (GCF) samples from non-inflamed gingiva sites in 2 healthy subjects and diseased sites in 7 patients with several types of periodontitis. IL-1 alpha, IL-1 beta and IL-1ra were measured by specific non-cross-reactive enzyme linked immunosorbent assay. The probing depth, gingival index and alveolar bone loss of each site was recorded at the time of GCF sampling. The total amount of IL-1 alpha, IL-1 beta and the IL-1AI, but not total IL-1ra, were found to be correlated with alveolar bone loss score. Three IL-1 molecules were also measured in the gingival tissue of patients with periodontitis. A similar progressive decrease of the IL-1AI was detected in gingival tissue with periodontitis. These results suggest that the amounts of both crevicular IL-1 and IL-1AI are closely associated with periodontal disease severity.

The pattern of interleukin-1beta (IL-1beta) and its modulating agents IL-1 receptor antagonist and IL-1 soluble receptor type II in acute meningococcal infections

Interleukin-1beta (IL-1beta) is considered an important mediator in the pathogenesis of septic shock or bacterial meningitis. Its activity is specifically modulated by IL-1 receptor antagonist (IL-1Ra) and IL-1 soluble receptor type II (IL-1sRII). We now describe the time-course of IL-1beta and these modulating agents in 59 patients with acute meningococcal infections, the prototype human disease of acute endotoxin exposure. Plasma IL-1beta was increased only in severe shock and normalized within 12 to 24 hours, indicating that patients were admitted in an early stage of cytokine activation. Increased IL-1beta values in cerebrospinal fluid (CSF) were confined to patients with meningitis. Plasma IL-1Ra was elevated in both shock and nonshock patients, extremely high values being measured in severe shock. High concentrations of IL-1Ra in CSF were found in meningitis. Plasma IL-1Ra peaked shortly after IL-1beta and decreased steeply in 1 to 2 days, followed by sustained moderately elevated levels in shock patients. Interestingly, IL-1sRII showed a completely different pattern. At admission, both nonshock and shock patients manifested a similar moderate increase of plasma IL-1sRII. However, during recovery plasma IL-1sRII further increased reaching maximal concentrations 3 to 5 days after admission, 1 to 2 days after normalization of IL-1Ra. In shock patients this increase was more prominent than in nonshock patients. It is hypothesized that this increase in plasma IL-1sRII can be explained by a synergistic effect of dexamethasone and endotoxin. A second interesting observation was that, unlike the pattern in plasma, IL-1sRII levels in CSF paralleled those of IL-1beta and IL-1Ra. This suggests different modulation of IL-1beta activity in the subarachnoid space and the plasma compartment. We conclude that: (1) During the early stage of meningococcal infections IL-1Ra modulates IL-1 activity, whereas during recovery IL-1sRII may be more important. (2) Modulation in CSF and in the plasma compartment are differentially regulated.

The IL-1 system in HIV infection: peripheral concentrations of IL-1beta, IL-1 receptor antagonist and soluble IL-1 receptor type II

The proinflammatory cytokine IL-1beta is thought to be involved in ongoing HIV disease. Furthermore, its naturally occurring inhibitors soluble IL-1 receptor type II (sIL-1RII) and IL-1 receptor antagonist (IL-1Ra) may play a pivotal role in regulating its biological action. To investigate the involvement of the IL-1 system we determined serum levels of IL-1beta, IL-1Ra and sIL-1RII in 90 HIV- patients. The obtained values were compared with markers of disease progression such as CD4+ count, 5'-neopterin. Beta2-microglobulin and soluble tumour necrosis factor receptors (sTNF-R) p55 and p75 and then compared with C-reactive protein (CRP), granulocyte count, IL-6 and TNF-alpha. While IL-1Ra concentrations increased significantly with progressive CDC disease stages, sIL-1RII and IL-1beta were not altered in our cohort. IL-1Ra showed statistical relation to decreasing CD4+ lymphocytes and increasing 5'-neopterin, beta2-microglobulin, sTNF-R p55, sTNF-R p75. Furthermore, IL-1Ra correlated positively with serum IL-6, TNF-alpha, CRP and granulocytes. In contrast, sIL-1RII and IL-1beta tended to show an inverse correlation or showed no significant relationship to all these parameters. IL-1beta was measurable only in a limited number of samples. IL-1Ra showed a clear relationship to acute inflammatory events as well as to the different disease stages. Our data suggest a dissociation between IL-1Ra and sIL-1RII serum levels which may indicate that the two IL-1 binding proteins have different pathophysiological roles in HIV infection.

Effect of inhaled glucocorticoids on IL-1 beta and IL-1 receptor antagonist (IL-1 ra) expression in asthmatic bronchial epithelium

BACKGROUND

Accumulating evidence suggests that the cytokine network is central to the immunopathology of bronchial asthma and the existence of naturally occurring cytokine antagonists has added to this complexity. Upregulation of both interleukin 1 beta (IL-1 beta) and its naturally occurring receptor antagonist, interleukin 1 receptor antagonist (IL-1ra), has previously been observed on asthmatic bronchial epithelium compared with normal airways.

METHODS

The effect of inhaled beclomethasone dipropionate (BDP) on asthmatic bronchial epithelial expression of IL-1 beta and IL-1ra was studied. Frozen bronchial biopsy specimens from nine asthmatic subjects receiving 1000 micrograms BDP daily for eight weeks and from six asthmatic subjects receiving matching placebo were stained with anti-IL-1 beta and anti-IL-1ra antibodies. Hue-saturation-intensity (HSI) colour image analysis was used to quantify the brown immunoperoxidase reaction colour present on the bronchial epithelium.

RESULTS

There was a significant twofold decrease in the epithelial expression of IL-1 beta after treatment with BDP but no significant change was seen in IL-1ra (P = 0.175).

CONCLUSION

The selective inhibition of IL-1 beta, without effect on IL-1ra, provides a novel mechanism for the anti-inflammatory action of glucocorticosteroids.

Immunostaining and transcriptional enhancement of interleukin-1 receptor type I in the rat dental follicle

Interleukin-1alpha (IL-1alpha) enhances the gene expression of colony-stimulating factor-one (CSF-1) in dental follicle cells. In turn, CSF-1 appears to be a critical molecule in stimulating the cellular events of eruption that require the presence of the follicle. Chronologically, the maximal transcription and translation of CSF-1 in the follicle occurs early postnatally, followed by a decline later. Thus, in this study, immunostaining for the interleukin-1 receptor type I (IL-1RI) was used to determine if it paralleled the CSF-1 localization and chronology. The results showed that IL-1RI is primarily localized in the dental follicle, with maximal immunostaining early postnatally and a greatly reduced staining by day 10. In conjunction with this, molecules that enhance the gene expression of IL-1alpha epidermal growth factor (EGF) and transforming growth factor-beta1 (TGF-beta1) were also shown to enhance the expression of IL-1RI, but IL-1alpha did not increase the gene expression of IL-1RI. After injections of EGF at different times postnatally the mRNA of IL-1RI increased over comparable controls. Between days 2 and 5 the IL-1RI mRNA in the follicle decreased. In combination the results suggest that, as the expression of IL-1alpha is enhanced in the stellate reticulum either by EGF or TGF-beta1, these two molecules could also enhance the expression of IL-1RI in the dental follicle such that more receptors would be available to respond to the increased IL-1alpha secreted. The maximal presence of the receptors (IL-1RI) in the dental follicle early postnatally, followed by their subsequent decline, parallels the rise and fall of CSF-1 in the follicle. Thus, regulation of the IL-1RI and IL-1RI gene expression might be a means of regulating changes in CSF-1 in the follicle.