There is more than one interleukin 1

Increased expression of mRNA encoding interleukin-1beta and caspase-1, and the secreted isoform of interleukin-1 receptor antagonist in the rat brain following systemic kainic acid administration

Kainic acid, an analogue of glutamate, injected systemically to rats evokes seizures that are accompanied by nerve cell damage primarily in the limbic system. In the present study, we have analyzed the temporal profile of the expression of the cytokines interleukin-1beta (IL-1beta) and IL-1 receptor antagonist (IL-1ra), and the related IL-1beta-converting enzyme (ICE/caspase-1), in different regions of the rat brain in response to peripheral kainic acid administration (10 mg/kg, i.p.). In situ hybridization histochemistry experiments revealed that IL-1beta mRNA-expressing cells, morphologically identified as microglial cells, were mainly localized to regions showing pronounced neuronal degeneration; hippocampus, thalamus, amygdala, and certain cortical regions. The strongest expression of IL-1beta mRNA was observed after 12 hr in these regions. A weak induction of the IL-1beta mRNA expression was observed already at 2 hr. Similar results were obtained by RT-PCR analysis, showing a significantly increased expression of IL-1beta mRNA in the hippocampus and amygdala after 12 hr. In addition, RT-PCR analysis revealed that IL-1ra mRNA, and specifically mRNA encoding the secreted isoform of IL-1ra (sIL-1ra), was strongly induced in the hippocampus and amygdala at 12 and 24 hr post-injection. RT-PCR analysis of mRNA encoding caspase-1 showed a significantly increased expression in the amygdala after 12 hr. In conclusion, in response to systemic kainic acid injection IL-1beta mRNA is rapidly induced and followed by induction of IL-1ra mRNA and caspase-1 mRNA, supporting a role of the IL-1 system in the inflammatory response during excitotoxic damage.

Interleukin 1alpha activity of peritoneal and bone marrow macrophages infected with Leishmania major and Leishmania donovani in vitro

In this study, the pattern of interleukin-1alpha (IL-1alpha) production by both peritoneal (PM) and bone marrow macrophages (BMM) from resistant (C3H/HeJ) and susceptible (BALB/c) mice was investigated, using a bioassay and an IL-1alpha-specific ELISA kit. PM from normal uninfected mice showed either an initial high (C3H/HeJ) or a neglected (BALB/c) level of IL-1alpha activity, respectively, probably due to thioglycollate stimulation. Infection with Leishmania major induced only a marginal effect on IL-1 production by both cells. Normal, uninfected and unstimulated BMM from both mice did not produce IL-1alpha over a 7-day period of cultivation in vitro. Upon stimulation with either lipopolysaccharide (LPS) (BALB/c) or concanavalin A (Con A) (C3H/HeJ), both cell types produced IL-1alpha that peaked within the first 12-24 h following stimulation. BMM from C3H/HeJ and BALB/c mice failed to produce IL-1alpha when infected in vitro with L. major or L. donovani promastigotes. However, infection with these two parasites did not interfere with the capability of the host cell to produce IL-1alpha when stimulated with LPS or Con A. The level of IL-1alpha production was independent of the degree of parasitization of the macrophages. Similar results were observed with IL-1beta and IL-6 production by BMM, even though their levels were generally slightly higher than those obtained with IL-1alpha.

New immunopharmacologic approaches to asthma: role of cytokine antagonism

This article involves an elucidation of the potential inflammatory mechanisms associated with the treatment of allergic disease and asthma, and the possibility of cytokine antagonism as a potential therapeutic mechanism for the treatment of those diseases. There is a review of the role of cytokines in the allergic process and a description of a number of studies done with the capacity of certain cytokine antagonists to develop potential amelioration of immune dysregulation in asthma and atopic states.

Effect of Hochu-ekki-to (TJ-41), a Japanese herbal medicine, on the survival of mice infected with influenza virus

The antiviral effect of Hochu-ekki-to (TJ-41), a Japanese herbal medicine, was investigated using mice infected with influenza virus. TJ-41 was found to increase the survival rate, prolong the mean survival days, suppress viral growth in bronchoalveolar labage fluid (BALF) and inhibit the lung index (lung consolidation) on day 4 after infection in mice infected with influenza, after the agent had been administered orally once daily from day 7 to 2 before infection and from day 0 to 4 after infection. Administration of TJ-41 decreased the BALF concentrations of IL-1alpha, IL-6 and GM-CSF, but not TNF-alpha or interferon-gamma (IFN-gamma), on day 4 after infection. In addition, TJ-41 elevated the level of IFN-alpha in BALF on day 2 after infection. Yet, TJ-41 did not show any inhibitory effect on the growth of influenza virus in vitro. These results suggest that TJ-41 exerts its inhibitory effect on influenza virus infection via enhancement of the host immune responses in this experimental murine system.

Time-dependent effects of stressor application on metastasis of tumor cells in the lung and its regulation by an immunomodulator in mice

The effects of the timing of stressor application on transplanted tumor cells and its possible regulation by an immunomodulator was investigated. Male C57 BL/6N mice were subjected to rotational stressor for 7 days relative to tumor cell inoculation: stressor after inoculation of Lewis lung cancer cells, stressor during inoculation and stressor before inoculation. Stressor application and tumor cell inoculation induced transient decreases in body weight, particularly in mice stressed after inoculation. The mice exposed to the stressor during inoculation or before inoculation showed significant increases in the number of metastatic foci relative to control mice. Early administration of an immunomodulator, PSK, significantly attenuated the increase of metastatic foci in stressed mice. The weights of thymus gland and spleen at 14 days after inoculation were similar in the three stressor groups and the control group. Application of the stressor reduced NK cell activity of the normal mice as well as tumor bearing mice. The lowest pre-inoculation NK cell activity was observed in mice stressed for 7 days beginning on the day of inoculation. The NK cell activity decreased in the tumor bearing mice which were stressed at the time of tumor inoculation. Decreased NK cell activity was reversed at day 14 after tumor inoculation. The mice exposed to the stressor after inoculation showed lowest level of NK cell activity relative to mice exposed to the stressor before or during inoculation. The treatment of mice with PSK reduced these changes significantly. The present results suggest that the rotational stress reduces splenic NK cell activity, which may influence the magnitude of tumor metastasis, depending on the time of tumor cell injection. Further, administration of an immunomodulator may counteract the reduction of the NK cell activity.

Contribution of inflammatory cytokine release to activation of resident peritoneal macrophages after in vivo low-dose gamma-irradiation

The activation mechanism of resident peritoneal macrophages by in vivo gamma-irradiation was investigated. The function of macrophages as accessory cells in concanavalin A-induced proliferation of spleno-lymphocytes (accessory function) was enhanced 4 h after a low-dose irradiation (4 cGy) in vivo, but not in vitro, indicating that low-dose irradiation acts indirectly on the activation of macrophages. Because we expected that macrophages were activated by the recognition of substances damaged by in vivo irradiation, we co-cultured macrophages with oxidized erythrocyte-ghosts. No change was found in their accessory function. The production of inflammatory cytokines, interleukin-1 beta (IL-1 beta) and interferon-gamma (IFN-gamma), in the supernatant of cocultures of spleno-lymphocytes and macrophages was determined by an ELISA. Production of both increased in the presence of in vivo irradiated macrophages. Furthermore, IL-1 beta production from in vivo-irradiated macrophages treated with recombinant IFN-gamma also was enhanced. The mRNA expression of the cytokines released from macrophages and lymphocytes was determined by RT-PCR. Increases in IL-1 beta mRNA expression were found in both in vivo- and in vitro-irradiated macrophages. In vivo irradiation also enhanced the expression of IFN-gamma mRNA in lymphocytes, whereas there was no change after in vitro irradiation. On the basis of these observations, we propose that the activation of macrophages is caused by interaction with neighboring cells, such as lymphocytes, and by paracrine induction of certain cytokines which is initiated by the small amount of IL-1 beta released by irradiated macrophages.

Overexpression of IL-1ra gene up-regulates interleukin-1beta converting enzyme (ICE) gene expression: possible mechanism underlying IL-1beta-resistance of cancer cells

We investigated the interaction of endogenous interleukin (IL)-1beta, IL-1ra, and interleukin-1beta converting enzyme (ICE) in four human urological cancer cell lines, KU-19-19, KU-1, KU-2 and KU-19-20. Northern blot analysis showed that IL-1beta gene was expressed in all cell lines. On the other hand, in KU-19-19 and KU-19-20, the gene expressions of both IL-1ra and ICE were suppressed. MTT assay revealed that IL-1beta (10 ng ml(-1)) promoted cell growth in KU-19-19 and KU-19-20, while it inhibited in KU-1 and KU-2. An ICE inhibitor, Acetyl-Tyr-Val-Ala-Asp-CHO (YVAD-CHO) blocked IL-1beta-induced growth inhibition in KU-1 and KU-2. Overexpression of the secretory type IL-1ra with adenovirus vector (AxlL-1ra) enhanced ICE gene expression, while exogenous IL-1ra (100 ng ml(-1)) did not enhance it. Furthermore, AxIL-1ra treatment promoted endogenous IL-1beta secretion and induced significant growth inhibition and apoptotic cell death on KU-19-19 and KU-19-20. Treatment with either IL-1ra (100 ng ml(-1)), IL-1beta antibody (100 microg ml(-1)), or YVAD-CHO blocked AxlL-1ra-induced cell death in KU-19-19 and KU-19-20. These results suggest that IL-1beta-sensitivity depends on the level of ICE gene expression, which is regulated by the level of endogenous slL-1ra expression. This is a first report on the intracellular function of slL-1ra and these findings may provide key insights into the mechanism underlying the viability of cancer cells.

Possible involvement of histamine in muscular fatigue in temporomandibular disorders: animal and human studies

As an approach to clarifying the molecular basis of pain and fatigue in muscles involved in temporomandibular disorders, we examined the activity of histidine decarboxylase (HDC), the enzyme which forms histamine, in the masseter muscles of mice. In the resting muscle, HDC activity was very low. Direct electrical stimulation of the muscle markedly elevated HDC activity. HDC activity rose within 3 hrs of the electrical stimulation, peaked at 6 to 8 hrs, and then gradually declined. Intraperitoneal injection of a small amount of interleukin-1 (IL-1) (from 1 to 10 microg/kg) produced a similar elevation of HDC activity in the masseter muscle. We also examined the effect of an antihistamine, chlorphenylamine (CP), on temporomandibular disorders in humans and compared it with that of an anti-inflammatory analgesic, flurbiprofen (FB). Two groups received one or the other of the drugs daily for 7 days, and they were asked about their signs and symptoms before and after the treatment. A positive evaluation of their treatment was made by 74% of the CP group, but by only 48% of the FB group. Although the effects of CP on the limitation of mouth-opening and on joint noise were negligible, about 50% of the CP group answered positively concerning the drug's effect on spontaneous pain or pain induced by chewing or mouth-opening. The positive evaluation for CP (50%) in relieving associated symptoms (headache or shoulder stiffness) was significantly greater than for FB (13%). FB showed effectiveness similar to but sometimes weaker than that of CP on several symptoms. On the basis of these and previous results and the known actions of histamine, we propose that the histamine newly formed following the induction of HDC activity, which is itself mediated by IL-1, may be involved in inducing pain and, possibly, stiffness in muscles in temporomandibular disorders.

Identification of a coelomic mitogenic factor in Eisenia foetida earthworm

Coelomic fluid of earthworms Eisenia foetida (Oligochaeta, Annelida) exerts a mitogenic activity on murine splenocytes. Total coelomic fluid was subjected to size-exclusion chromatography and a semi-purified mitogenic fraction (fraction 5) was isolated and further characterized. Both coelomic fluid and the semi-purified fraction 5 block concanavalin A (ConA)-induced spleen cell proliferation but exert a synergistic effect on LPS-triggered spleen cell proliferation. Using a polyclonal antiserum neutralizing the mitogenic activity of the semi-purified fraction 5, a 60-kDa component was identified and named CMF (coelomic mitogenic factor). CMF was found to bind ConA which could account for its ability to inhibit ConA-induced spleen cell proliferation. CMF is present in the coelomic fluid as a trimer of a 20-kDa protein. N-terminal amino acid sequence of monomeric CMF reveals partial sequence homology with phospholipase A2 (PLA2). Moreover, CMF-enriched coelomic fluid fraction 5 exerts phospholipase activity comparable with that of bovine pancreatic PLA2. Our results suggest that coelomic fluid of E. foetida contains a ubiquitous PLA2-like enzyme which might be involved in immune reactions in earthworms such as anti-bacterial mechanisms.

Pathophysiological role of the cytokine network in the anterior pituitary gland

Recent evidence has demonstrated that cytokines and other growth factors act in the anterior pituitary gland. Using the traditional criteria employed to determine autocrine or paracrine functions our review shows that, in addition to their role as lymphocyte messengers, certain cytokines are autocrine or paracrine regulators of anterior pituitary function and growth. The cytokines known to regulate and/or be expressed in the anterior pituitary include the inflammatory cytokine family (IL-1 and its endogenous antagonist, IL-1ra; TNF-alpha, and IL-6), the Th1-cytokines (IL-2 and IFN-gamma), and other cytokines such as LIF, MIF, and TGF-beta. This review examines at the cellular, molecular, and physiological levels whether: (1) each cytokine alters some aspect of pituitary physiology; (2) receptors for the cytokine are expressed in the gland; and (3) the cytokine is produced in the anterior pituitary. Should physiological stimuli regulate pituitary cytokine production, this would constitute additional proof of their autocrine/paracrine role. In this context, we analyze in this review the current literature on the actions of cytokines known to regulate anterior pituitary hormone secretion, selecting the in vivo studies that support the direct action of the cytokine in the anterior pituitary. Further support for direct regulatory action is provided by in vitro studies, in explant cultures or pituitary cell lines. The cytokine receptors that have been demonstrated in the pituitary of several species are also discussed. The endogenous production of the homologous cytokines and the regulation of this expression are analyzed. The evidence indicating that cytokines also regulate the growth and proliferation of pituitary cells is reviewed. This action is particularly important since it suggests that intrinsically produced cytokines may play a role in the pathogenesis of pituitary adenomas. The complex cell to cell communication involved in the action of these factors is discussed.

The effects of ginseng radix rubra on human vascular endothelial cells

The effect of Ginseng Radix Rubra (Red ginseng) on human vascular endothelial cells was examined. Red ginseng was found to promote the proliferation of vascular endothelial cells, inhibit the production but promote the decomposition of endothelin, which is known to constrict blood vessels and raise blood pressure as well as accelerated the synthesis of nitric oxide, which is known to have an angio-tonic effect. Furthermore, Red ginseng was observed to increase the production of Interleukin 1 beta, which is known to play important roles in the homeostatic activities of the human body such as immunity and inflammation as well as increasing the production of tissue plasminogen activators, which suppress the formation of thrombin in the blood coagulation and fibrinolysis mechanisms. It is suggested that Red ginseng has the effect of accelerating endothelial cells proliferation and of promoting physiological activities.

The G1-phase growth-arresting action of interleukin-1 is independent of p53 and p21/WAF1 function

Interleukin-1 (IL-1) causes G1-phase growth arrest of A375-C6 human melanoma cells by hypophosphorylation of the retinoblastoma susceptibility gene product Rb. Because p53 and p21/WAF1 proteins are key components of growth arrest pathways involving Rb hypophosphorylation, we tested the functional role of these two proteins in IL-1 action. Exposure to IL-1 caused induction of both p53 and p21/WAF1 proteins. However, inhibition of p53 function by the K1 mutant of SV40-T antigen or by m175 (Arg to His) dominant-negative mutant of p53 did not result in abrogation of IL-1 action, suggesting that p53 function is not required for growth arrest by IL-1. Studies aimed at testing the role of p21/WAF1 in IL-1 action indicated that IL-1 induced p21/WAF1 expression independently of the p53 status of the cells. However, inhibition of p21/WAF1 expression resulted in only a marginal rescue from the growth-arresting action of IL-1. These findings imply that despite their induction, neither wild-type p53 nor p21 can fully account for the growth arrest by IL-1. Thus, a p53- and p21-independent pathway(s) mediates IL-1 action.

Keratinocyte growth factor and its receptor messenger RNA expression in nasal mucosa and nasal polyps

To examine the potential biologic role of fibroblast growth factors (FGFs) in nasal polyps and nasal mucosa during chronic inflammatory conditions, we investigated messenger RNA (mRNA) expression of three members of the FGF family -- acidic FGF, basic FGF, and keratinocyte growth factor (KGF)-- in nasal polyp tissues, as well as in hyperplastic nasal mucosa. Using the sensitive method reverse transcription-polymerase chain reaction (RT-PCR), we demonstrated that of the examined FGFs, KGF had the most abundant mRNA expression in nasal polyps and nasal mucosa. We also found that significantly higher levels of KGF mRNA were expressed in nasal polyps than in nasal mucosa, whereas mRNA expression of acidic FGF and basic FGF was relatively low in these tissues. In addition, we showed that KGF receptor mRNA was present in most of the nasal mucosa; however, none or little was expressed in nasal polyps. These results suggest that KGF might play an important role in nasal epithelial proliferation and that excessive synthesis of KGF in nasal polyp stroma may contribute to hypertrophy of the nasal mucosa in patients with chronic sinusitis associated with nasal polyposis.

Induction by interleukin-1beta peptide of prostaglandin E2 formation via enhanced prostaglandin H synthase-2 expression in 3T6 fibroblasts

Several synthetic interleukin-1 (IL-1) peptides were tested in vivo for pyrogenic activity and in vivo for their ability to stimulate prostaglandin production. Only the IL-1beta fragment (208-240) enhanced body temperature, although both IL-1beta (208-240) and IL-1alpha (223-250) stimulated prostaglandin E2 (PGE2) production in vitro. We report here that the IL-1beta fragment (208-240) did not have the capacity to induce arachidonic acid (AA) mobilization by 3T6 fibroblasts. However, this peptide was able to increase the expression of the inducible prostaglandin H synthase isoform (PGHS-2; EC 1.14.99.1.), which is related to its ability to stimulate prostaglandin E2 synthesis.

Cytokine expression in periodontal health and disease

Soluble proteins that serve as mediators of cell function and are produced by various cell types, such as structural and inflammatory cells, are collectively called cytokines. Several lines of evidence have revealed that cytokines play important roles not only in tissue homeostasis but also in the pathogenesis of many infectious diseases. Recent research on biological activities in normal periodontium and the pathogenesis of periodontal diseases has clarified the involvement of various cytokines in the biological activities observed in the sites. Cytokines play crucial roles in the maintenance of tissue homeostasis, a process which requires a delicate balance between anabolic and catabolic activities. In particular, growth factors--such as fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), insulin-like growth factor (IGF), transforming growth factor-beta (TGF-beta)--are thought to play important roles in modulating the proliferation and/or migration of structural cells in the periodontium and the production of various extracellular matrices by these cells. On the other hand, there is little doubt that excessive and/or continuous production of cytokines in inflamed periodontal tissues is responsible for the progress of periodontitis and periodontal tissue destruction. Particularly, inflammatory cytokines--such as IL-1 alpha, IL-1 beta, IL-6, and IL-8--are present in the diseased periodontal tissues, and their unrestricted production seems to play a role in chronic leukocyte recruitment and tissue destruction. It is possible that monitoring cytokine production or its profile may allow us to diagnose an individual's periodontal disease status and/or susceptibility to the disease. In addition, although the hypothesis is still controversial, it has been suggested that discrete T-cell subsets (Th1 and Th2) with different cytokine profiles play specific roles in the immunopathogenesis of periodontal diseases.

Association between oxidative stress and cytokine production in nickel-treated rats

The aim of this study was to evaluate a possible relationship between lipid peroxidation, cytokine production, such as interleukin-1 (IL-1), tumor necrosis factor alpha (TNF-alpha), and transforming growth factor beta (TGF-beta), and hepatotoxicity of rats after nickel chloride (NiCl2) acute poisoning. Administration of NiCl2 significantly elevated the levels of malondialdehyde (MDA), IL-1, TNF-alpha, and TGF-beta in the serum of rats. The dose-effect relationship for the increase of serum MDA, as observed in the present study, corresponds closely to the increase of IL-1, TNF-alpha, and TGF-beta in serum. Treatment with ascorbic acid (Vit C) significantly lowered the levels of lipid peroxidation, cytokine production, and the activities of alanine transaminase and aspartate transaminase in the serum of the rats given NiCl2. The hepatic toxicity was increased in a dose-dependent manner and corresponds to the increase of serum IL-1, TNF-alpha, and TGF-beta. There was an association between lipid peroxidation and the levels of cytokines in serum of rats after NiCl2 administration. Reactive oxygen species may serve as a mediator of lipid peroxidation and production of cytokines in NiCl2 injection.

The relationship between concentrations of proinflammatory cytokines within gingiva and the adjacent sulcular depth

The objective of this study was to determine and compare concentrations and ratios of 3 proinflammatory cytokines, interleukin (IL) IL-1beta, IL-6, and IL-8 within gingival tissue biopsies adjacent to < or = 3, 4 to 6, or >6 mm sulci. All gingiva adjacent to > or = 4 mm sulci had clinical evidence of active inflammation. Factorial analysis of variance suggested significant effects of sulcus depth on the type and concentration of the three cytokines in the adjacent gingiva (P < 0.001). IL-8 concentrations were highest in gingiva adjacent to < or = 3 and lowest adjacent to >6 mm sulci (P < 0.001). In contrast, IL-6 concentrations were lowest in gingiva adjacent to < or = 6 mm and highest adjacent to >6 mm sites. IL-1beta concentrations were highest in gingiva adjacent to >6 mm and lowest adjacent to 4 to 6 mm sites; they were also higher adjacent to < or = 3 mm than adjacent to 4 to 6 mm sites (P < 0.01). Multiple regression analysis suggested that sulcular depth, type of cytokine, and cytokine concentration were significantly correlated (P < 0.001). Ratios of gingival cytokines changed with increased sulcular depth. In gingiva adjacent to < or = 6 mm sites, IL-8 was the most and IL-6 the least prevalent. In gingiva adjacent to > or = 6 mm sites, IL-8 was the least and IL-1-beta the most prevalent. The data suggest that the characteristics of the gingival cytokine network are affected by adjacent sulcular depth. These data could be used to design adjunct diagnostic tests for progression of periodontal diseases.

The Th1 and Th2 cytokines IFN-gamma and IL-4 antagonize the inhibition of monocyte IL-1 receptor antagonist by glucocorticoids: involvement of IL-1

Monocytes express IL-1 and IL-1 receptor antagonist (IL-1Ra) in response to lipopolysaccharide (LPS). IL-1 self-induction contributes to the increase in IL-1 following LPS stimulation. LPS-stimulated IL-1 and IL-1Ra production are inhibited by glucocorticoids. In the present work we examined the regulation of IL-1Ra by Th1 cytokine IFN-gamma, Th2 cytokine IL-4, glucocorticoids and IL-1 in human monocytes. We demonstrate that IL-1 contributes to LPS-induced IL-1 Ra expression as shown by IL-1 blockade in LPS-stimulated monocytes using a specific anti-IL-1beta antibody or recombinant IL-1Ra. Glucocorticoids inhibited IL-1beta-stimulated IL-1Ra mRNA expression and protein production. Glucocorticoids inhibited both IL-1-mediated and non-mediated LPS stimulation of IL-1Ra expression. Both IFN-gamma and IL-4 reversed the inhibitory effect of glucocorticoids on IL-1Ra expression and secretion. The effect of IFN-gamma was blocked by pretreatment of monocytes with an anti-IL-1beta blocking antibody, whereas the effect of IL-4 could not be blocked, demonstrating that IFN-gamma acts through a mechanism dependent on endogenous IL-1 production, whereas IL-4 acts through an IL-1-independent one. Consistent with this finding, IFN-gamma (but not IL-4) failed to reverse the inhibitory effect of glucocorticoids when stimulated by IL-1, and only IL-4 combined with IL-1 showed synergism resulting in an increase in IL-1 Ra production. The differential regulation and involvement of IL-1 in the expression of IL-1Ra by IFN-gamma, IL-4 and glucocorticoids sets the level of monocyte responsiveness during the Th1 or Th2 responses.

Development of periradicular lesions in immunosuppressed rats

PROBLEM

The role of bacteria has been well established in pulpal and periapical diseases, but the contribution of the host defenses is less clear.

OBJECTIVES

The purpose of this study was to compare periradicular lesion development in immunosuppressed rats with that in normal rats.

STUDY DESIGN

Fifteen rats were given weekly injections of Cytoxan (Bristol Laboratories) to suppress their immune systems. The pulps of mandibular first molars of these animals and another 15 rats that had received no medications were exposed and left open to their oral flora. The rats were killed at 2, 4, and 6 weeks. Radiographic analysis was performed by means of a computer linked to a digitizing board and stylus. In addition, specimens were decalcified, sectioned, stained, and examined under a microscope with a grid to quantify relative percentages of surface areas of bone, root, periodontal ligament, marrow spaces, soft tissue, and inflammatory infiltrate.

RESULTS

Statistical analysis showed a significantly greater radiographic bone loss in the immunosuppressed group only at 4 weeks. No significant histologic differences were found between the two groups.

CONCLUSION

Our results suggest that reduction of circulating leukocytes may not significantly affect the development of periradicular pathosis in rats.

Induction of histidine decarboxylase in skeletal muscle in mice by electrical stimulation, prolonged walking and interleukin-1

1. In normal non-exercised skeletal muscles in mice, the activity of histidine decarboxylase (HDC), the enzyme which forms histamine, was very low. 2. HDC activity in the quadriceps femoris muscle was markedly elevated following contractions evoked by even a few minutes of direct electrical stimulation, peaking at 8-12 h following contraction lasting 10 min, and gradually decreasing during the 24 h following contraction. The elevation in HDC activity depended on the duration and strength of stimulation. 3. Direct electrical stimulation induced a quantitatively similar elevation of HDC activity in the muscles of mast-cell-deficient mice (W/Wv mice). 4. Prolonged walking at a speed of 6 m min-1 for up to 6 h with a 30 min rest period at 3 h also elevated muscle HDC activity, the magnitude of the elevation being related to the duration of the walking. Repeated exercise (training) for several days diminished the elevation of muscle HDC activity induced by walking. In contrast, starvation augmented the elevation of muscle HDC activity induced by walking. 5. Intraperitoneal injection of interleukin-1beta (IL-1beta) also elevated muscle HDC activity in a dose-dependent manner, as little as 1 microg kg-1 of IL-1 producing a significant elevation of muscle HDC activity. 6. IL-1beta was immunohistochemically detected in normal non-exercised quadriceps femoris muscle. We could not detect a significant increase in IL-1beta after exercise in the muscle or in serum: it may be below the level of detection. 7. On the basis of these results, together with those reported previously and the known actions of histamine, we propose that an elevation of HDC activity and generation of histamine occur in skeletal muscle following muscle contraction possibly as a result of induction by IL-1beta and that the histamine may be involved in fatigue in skeletal muscle as part of a defence mechanism preventing damage to the muscle.

Glycosaminoglycan metabolism and cytokine release in normal and otosclerotic human bone cells interleukin-1 treated

Glycosaminoglycans (GAGs), normal components of the extracellular matrix (ECM), and the glycosidases, that degrade them, play a key role in the bone remodelling process. The effects of interleukin-1 alpha (IL-1 alpha) on GAG metabolism in normal and otosclerotic human bone cells as well as its capacity to modulate IL-1 alpha, IL-1 beta and IL-6 secretion in both populations was analyzed. The amount of radiolabeled GAGs was lower in otosclerotic than in normal bone cells. IL-1 alpha reduced newly synthesized cellular and extracellular GAGs in normal cells, but only those of the cellular compartment in otosclerotic bone cells. It depressed heparan sulphate (HS) more in normal cells and chondroitin sulphate (CS) more in otosclerotic bone cells. The HA/total sulphated GAG ratio was shifted in favour of the latter in otosclerotic cells, whereas the opposite effect was seen after IL-1 alpha treatment. There was little difference in the beta-D-glucuronidase levels of the normal and pathological cells, while beta-N-acetyl-D-glucosaminidase was significantly increased in otosclerotic bone cells. As the activity of neither enzyme was modified by treatment with IL-1 alpha, the cytokine seems to exert its influences on GAG synthesis rather than on the degradation process. IL-1 alpha, IL-1 beta and IL-6 secretion was markedly higher in otosclerotic cells. IL-1 alpha modulated the secretion of each interleukin differently, thus resulting in a cytokine cascade that may act in autocrine/paracrine manner on target cells. The authors suggest that changes in the cytokine network may have a specific, yet still unknown, role during normal and pathological osteogenesis.

Mercury-induced autoimmunity in Brown Norway rats: kinetics of changes in RT6+ T lymphocytes correlated with IgG isotypes of circulating autoantibodies to laminin 1

Repeated exposure to mercury causes various autoimmune effects in rats of the Brown Norway (BN) strain. Previous studies from our laboratory have shown that on day 15 of HgCl2 treatment BN rats exhibit a relative decrease in RT6.2+ T cells. At the same time, they produce high levels of autoantibodies to renal antigens and experience a membranous glomerulonephropathy. In contrast, Lewis (LEW) rats are resistant to autoimmunity caused by mercury and do not demonstrate a decrease in RT6+ cells after administration of HgCl2. In the present paper we provide novel information on the correlation between changes in RT6.2+ lymph node T cells and the production of autoantibodies to laminin 1, obtained by detailed kinetic studies of HgCl2-treated BN rats. We have confirmed a decrease in the percentage of RT6.2+ lymphocytes on day 15 of mercury treatment, despite a significant increase in the number of peripheral lymphocytes. No such changes were observed in LEW rats. We have determined that on day 15 the percentage decrease in RT6+ cells is evident in both RT6.2+CD4+ and RT6.2+CD8+ T cell subsets. Kinetic studies demonstrated that significant changes in the percentage of RT6.2+ cells are first observed by day 8 and continue through days 11 and 15. We have also observed a significant percent decrease in CD4+ T lymphocytes as well as an increase in CD4-CD8- cells. The dramatic increase in the percentage of these double negative cells at the level of peripheral lymphoid tissues does not appear to be due to higher thymic output, since there was a decrease in the percentage of TCR+Thy1+ cells, a phenotype that is associated with recent thymic emigrants. Finally, we have demonstrated that 100% of HgCl2-treated BN rats had circulating antibodies that reacted with both mouse and rat laminin 1, i.e. are autoantibodies to laminin 1. These autoantibodies were predominantly of the IgG1 and IgG2a isotype, possibly as the result of a polarized autoimmune response driven by Type 2 cytokines. A kinetic investigation showed that significant levels of IgG1 and IgG2a autoantibodies to laminin 1 were first presentin the circulation by day 11. The inverse correlation between levels of RT6.2+ T lymphocytes and autoantibodies to laminin 1 suggests that mercury may induce autoimmune responses in BN rats by its effects on these immunoregulatory cells.

Interleukin-1 receptor (IL-1R) liquid formulation development using differential scanning calorimetry

PURPOSE

To elucidate the solution conditions that confer stability of aqueous IL-1R using differential scanning calorimetry (DSC).

METHODS

Optimal pH conditions were determined by monitoring degradation products encountered during accelerated studies (at elevated temperatures) using SDS-PAGE. At the pH optimum, DSC screened for excipients that enhanced thermal stability by shifting the Tm to higher values. Using SEC the relationship between thermal unfolding and stability was investigated by considering if lower Tm's in the presence of preservatives correlated with degradation products at 37 degrees C over time. The degree of aggregation relative to that of a control determined the level of stability achieved.

RESULTS

Circular dichroism (CD) measurements confirmed molecular modeling studies showing IL-1R to be about 39% beta-sheet. Two major transitions characterized the DSC data with Tm's observed near 47 degrees C and 66 degrees C. Among 21 excipients screened, NaCl exhibited the greatest stabilizing influences based on shifting the low temperature transition to 53 degrees C. The low temperature transition was later found to comprise two transitions, yielding a total of three melting transitions for IL-1R. High Tm's arising from the presence of preservatives correlated with the order of stability (i.e., 0.065% phenol > 0.1% m-Cresol > 0.9% benzyl alcohol).

CONCLUSIONS

The three melting transitions are consistent in origin with the cooperative unfolding of three unique immunoglobulin-like domains of IL-1R. Optimal stability was achieved in 20 mM sodium citrate at pH 6 with sufficient NaCl to attain the tonicity of human serum. A correlation between the predicted ranking of stability and the extent of aggregation was demonstrated using DSC.

Lipopolysaccharide Activates Caspase-1 (Interleukin-1–Converting Enzyme) in Cultured Monocytic and Endothelial Cells

Interleukin-1β (IL-1β) is a pleiotropic proinflammatory cytokine. Mechanisms leading to its secretion include not only release of newly synthesized protein, but also cleavage of a preformed immature precursor protein into an active secretory form by the intracellular protease caspase-1 (formerly termed IL-1–converting enzyme [ICE]). Caspase-1 belongs to a rapidly growing family of cysteine proteases with substrate specificity for aspartate involved in cellular apoptosis. We have used an assay determining the caspase-1 activity based on cleavage of a fluorogenic peptide substrate to elucidate its role in lipopolysaccharide (LPS)-induced secretion of IL-1β. We show that LPS induces moderate caspase-1 activity in the monocytic cell line THP-1, in freshly isolated peripheral blood monocytes, and in human umbilical vein endothelial cells (HUVECs) in a time- and dose-dependent fashion. Caspase-1 activation by LPS was associated with cleavage of the IL-1β precursor protein that was followed by release of the mature IL-1β protein in monocytic cells. In contrast, subsequent release of IL-1β by HUVECs was not significant. LPS-induced caspase-1 activation appeared not to result from modulation of caspase-1 transcript accumulation and inhibition of caspase-1 activity was accomplished by two specific inhibitors, YVAD-CHO and YVAD-CMK, capable of alleviating the release of mature IL-1β. Taken together, these results show that LPS moderately activates caspase-1 and that caspase-1 activation contributes to LPS induction of IL-1β secretion.

Lipopolysaccharide Activates Caspase-1 (Interleukin-1–Converting Enzyme) in Cultured Monocytic and Endothelial Cells

Interleukin-1β (IL-1β) is a pleiotropic proinflammatory cytokine. Mechanisms leading to its secretion include not only release of newly synthesized protein, but also cleavage of a preformed immature precursor protein into an active secretory form by the intracellular protease caspase-1 (formerly termed IL-1–converting enzyme [ICE]). Caspase-1 belongs to a rapidly growing family of cysteine proteases with substrate specificity for aspartate involved in cellular apoptosis. We have used an assay determining the caspase-1 activity based on cleavage of a fluorogenic peptide substrate to elucidate its role in lipopolysaccharide (LPS)-induced secretion of IL-1β. We show that LPS induces moderate caspase-1 activity in the monocytic cell line THP-1, in freshly isolated peripheral blood monocytes, and in human umbilical vein endothelial cells (HUVECs) in a time- and dose-dependent fashion. Caspase-1 activation by LPS was associated with cleavage of the IL-1β precursor protein that was followed by release of the mature IL-1β protein in monocytic cells. In contrast, subsequent release of IL-1β by HUVECs was not significant. LPS-induced caspase-1 activation appeared not to result from modulation of caspase-1 transcript accumulation and inhibition of caspase-1 activity was accomplished by two specific inhibitors, YVAD-CHO and YVAD-CMK, capable of alleviating the release of mature IL-1β. Taken together, these results show that LPS moderately activates caspase-1 and that caspase-1 activation contributes to LPS induction of IL-1β secretion.

Characterization of a second transcription initiation element (STIE) in the human interleukin-1 beta (IL-1beta) gene

Interleukin-1-beta (IL-1beta) is a significant mediator in the inflammation process. Although the human IL-1beta genomic sequence has been known for several years, our understanding of its molecular regulation of transcription remains incomplete. We are reporting a new transcription initiation element that is located within intron 1 and exon 2 of the human IL-1beta gene. Different lengths of the human IL-1beta gene fragment (-685 to +550) were cloned upstream from a chloramphenical acetyltransferase (CAT) gene to make the IL-1beta promoter/CAT reporter constructs. Transient CAT expression with these constructs in the human monocytic leukemia cell line THP1 illustrates an important positive regulatory element exists within the region from +387 to +550. Using electromobility shift assays and by DNase I footprinting analysis, we identified three nuclear factor binding sites (+448 to +502, +513 to +531, and +539 to +548). Functional studies show that CAT production is undetectable when the 19 bp region (+513 to +531) is removed, and CAT production is diminished when the 10-bp region (+539 to +548) is deleted. The region containing these sites is likely to initiate a new transcript starting at +559 of exon 2. This second transcript of the IL-1beta gene shares the same reading frame with the previously recognized cDNA transcript.

Role of circulating endotoxin and interleukin-6 in the ACTH and corticosterone response to intraperitoneal LPS

Peripheral administration of lipopolysaccharide (LPS) may activate the hypothalamus-pituitary-adrenal (HPA) axis by way of both neural and humoral mechanisms. We have investigated whether biologically active endotoxin appears in the general circulation after intraperitoneal administration of LPS (5 or 100 micrograms/kg) to rats and whether this is a prerequisite for activation of this HPA axis. Within 15 min, endotoxin appeared in the general circulation, whereas elevations of plasma adrenocorticotropic hormone (ACTH), corticosterone, and interleukin (IL)-6 concentrations were not detected until 90 min after LPS injection. At this time, a marked interindividual variation was observed in plasma concentrations of endotoxin, ACTH, corticosterone, and IL-6. Elevated levels of plasma endotoxin were associated with elevated levels of ACTH, corticosterone, and IL-6. Intravenous administration of the LPS antagonist cationic antimicrobial protein 18 (5 mg/kg), which did not affect cytokine production in the peritoneal cavity, markedly reduced plasma ACTH, corticosterone, and IL-6 levels after 5 micrograms/kg LPS. Our results suggest that circulating endotoxin is required for the activation of the HPA axis. They also favor a role for circulating IL-6 in this response.

Phase 1 trial of recombinant human interleukin-1 beta (rhIL-1 beta), carboplatin, and etoposide in patients with solid cancers: Southwest Oncology, Group Study 8940

Recombinant human interleukin-1 beta (rhIL-1 beta) was evaluated in a phase 1 clinical trial in which patients with metastatic or unresectable solid tumors received carboplatin and etoposide in cycle 1 and carboplatin, etoposide, and rhIL-1 beta in cycle 2. Recombinant hIL-1 beta was given intravenously for 5 days in one of three schedules: (1) immediately postchemotherapy, (2) delayed for 5 days after chemotherapy, or (3) concurrently with chemotherapy. Four dose levels of rhIL-1 beta were evaluated: 20, 50, 100, and 200 ng/kg. The doses of carboplatin and etoposide were not changed between cycle 1 and cycle 2 so that the effect of rhIL-1 beta on chemotherapy-induced hemato-toxicity was evaluated; 54 patients were entered on study and 42 patients received at least two cycles of therapy and were thus evaluable for rhIL-1 beta toxicity and for the effect of rhIL-1 beta on hematotoxicity of carboplatin and etoposide. The major toxicities of rhIL-1 beta were chills, rigors, headache, fatigue, and hypotension. The maximum tolerated dose of rhIL-1 beta was not determined since the toxicities at all dose levels were similar. However, only 3/8 patients at the 200 ng/kg level received all 5 IL-1 beta infusions. We compared the effect of rhIL-1 beta on hematotoxicity of carboplatin/etoposide by comparing peripheral blood count parameters between cycles 1 and 2: rhIL-1 beta given postchemotherapy significantly increased absolute neutrophil count (AND) nadirs and improved neutrophil recovery times regardless of rhIL-1 beta dose level. Platelet count parameters were also improved when rhIL-1 beta was given postchemotherapy although these changes did not reach statistical significance. Thus, IL-1 beta exhibited extensive hematological effects but the usefulness of this agent in clinical practice will be limited by extensive toxicity at all tested dose levels.

Biologically active, alternatively processed interleukin-1 beta in psoriatic scales

The aims of the present work were to elucidate the biochemical properties of interleukin-1 beta (IL-1 beta) in psoriatic scales to get information on the processing of epidermal IL-1 beta in psoriasis, and to elucidate whether the IL-1 beta in psoriatic scales possesses biological activity. By means of ion exchange chromatography, IL-1 beta in extracts of psoriatic scales was purified to a stage where it could be analyzed with electrophoretic methods and immunoblotting. Compared to mature recombinant human IL-1 beta (Ala 117 IL-1 beta), IL-1 beta in psoriatic scales had a slightly higher apparent molecular mass and a more acidic isoelectric point, as revealed by two-dimensional electrophoresis under denaturing conditions. Isoelectric focusing under non-denaturing conditions of IL-1 beta partially purified from psoriatic scales, or from non-inflamed plantar stratum corneum (Nylander Lundqvist, E., Bäck, O. and Egelrud, T., J. Immunol. 1996. 157: 1699), and of mature IL-1 beta, followed by immunoblotting with IL-1 beta-specific antibodies, showed that psoriatic scales contained two components with IL-1 beta-like immunoreactivity which were isoelectric at pH 6.1 and 6.3, respectively. These components could also be detected in extracts of plantar stratum corneum, which also contained small amounts of an IL-1 beta-like component isoelectric at pH 6.9. Mature IL-1 beta was isoelectric at pH 6.9. No IL-1 beta-like biological activity could be detected in crude extracts of psoriatic scales. These extracts also contained high amounts of IL-1 receptor antagonist. Partially purified preparations of IL-1 beta from psoriatic scales, in which an apparently total separation of IL-1 beta and IL-1 receptor antagonist had been achieved, could induce expression of E-selectin in human umbilical vein endothelial cells. This activity was inhibited by antibodies specific for IL-1 beta, but not by antibodies specific for IL-1 alpha. It is concluded that psoriatic scales contain biologically active IL-1 beta, which has been processed by a mechanism which may be similar to that present in non-inflamed plantar stratum corneum, and which does not involve IL-1 beta converting enzyme.

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.

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.

p38 mitogen-activated protein kinase down-regulates nitric oxide and up-regulates prostaglandin E2 biosynthesis stimulated by interleukin-1beta

The inflammatory cytokine interleukin 1beta (IL-1beta) induces both cyclooxygenase-2 (Cox-2) and the inducible nitric-oxide synthase (iNOS) with increases in the release of prostaglandins (PGs) and nitric oxide (NO) from glomerular mesangial cells. However, the intracellular signaling mechanisms by which IL-1beta induces iNOS and Cox-2 expression is obscure. Our current studies demonstrate that IL-1beta produces a rapid increase in p38 mitogen-activated protein kinase (MAPK) phosphorylation and activation. Serum starvation and SC68376, a drug which selectively inhibits p38 MAPK in mesangial cells, were used to investigate whether p38 MAPK contributes to the signaling mechanism of IL-1beta induction of NO and PG synthesis. Serum starvation and SC68376 selectively inhibited IL-1beta-induced activation of p38 MAPK. Both SC68376 and serum starvation enhanced NO biosynthesis by increasing iNOS mRNA expression, protein expression, and nitrite production. In contrast, both SC68376 and serum starvation suppressed PG release by inhibiting Cox-2 mRNA, protein expression, and PGE2 synthesis. These data demonstrate that IL-1beta phosphorylates and activates p38 MAPK in mesangial cells. The activation of p38 MAPK may provide a crucial signaling mechanism, which mediates the up-regulation of PG synthesis and the down-regulation of NO biosynthesis induced by IL-1beta.

Interleukin-1-induced growth inhibition of human melanoma cells. Interleukin-1-induced antizyme expression is responsible for ornithine decarboxylase activity down-regulation

Interleukin (IL)-1 is a multi-functional cytokine and regulates cell growth either positively or negatively. Previous studies have shown that IL-1-induced ornithine decarboxylase (ODC) activity down-regulation is involved in the anti-proliferative effect of IL-1 on human A375 melanoma cells. In this study, we examined the IL-1alpha-induced molecular events resulting in ODC activity down-regulation in C2-1, a A375 cell line stably transfected with human type I IL-1 receptor. Recombinant human (rh) IL-1alpha inhibited the growth and down-regulated the ODC activity of C2-1 cells in a dose-dependent manner. Kinetics studies showed that both the DNA synthesis and ODC activity of C2-1 cells progressively decreased from 12 h after IL-1 addition. Northern hybridization showed that IL-1 had no influence on ODC mRNA level. However, rhIL-1 induced both a decrease of ODC protein and an ODC-inhibiting activity in IL-1-treated C2-1 cells. IL-1 specifically up-modulated the mRNA level of antizyme, a protein essential for ODC regulation, but had little effect on its stability. IL-1-induced antizyme up-modulation preceded IL-1-induced down-regulation of ODC protein, ODC activity, and DNA synthesis in C2-1 cells. Run-on transcription analysis confirmed that the increased antizyme mRNA expression was due to elevated antizyme gene transcription. Furthermore, the action of IL-1 to inhibit the ODC activity and growth of C2-1 cells was blocked by expressing the antisense RNA of human antizyme in C2-1 cells. These results suggest that IL-1-induced antizyme expression is responsible for IL-1-induced ODC activity down-regulation in human melanoma cells.

A negative regulatory region containing a glucocorticosteroid response element (nGRE) in the human interleukin-1beta gene

Interleukin-1 beta (IL-1beta) is one of the most important inflammatory mediators in human inflammatory and immunological diseases. The regulation of human IL-1beta gene expression has been studied for several years, and a few regulatory elements have been discovered in the promoter region. However, little is known about negative regulation of IL-1beta expression at the transcriptional level, which may play an important role in anti-inflammatory and immunosuppressive effects. We have identified a negative regulatory element located in the region between -685 and -395. Within this region, a 19-bp nuclear factor binding site (-570 to -552) was characterized by DNase I footprinting and electromobility shift assay. A consensus sequence for a negative glucocorticoid response element (nGRE) and a transcription activator protein-2 binding site were noted within this footprint. Functional studies showed a 2.5-fold increase in promoter activity when this 19-bp binding site was deleted in the reporter constructs IL-1beta/CAT and IL-1beta/SV40 promoter/CAT. Dexamethasone (10(-8) M) repressed chloramphenicol acetyltransferase (CAT) production by 75% in the wild-type fragment but not in a deletion mutant lacking the 19-bp site. A protein of about 150 kD that bound to this negative regulatory sequence was identified by UV cross-linking. This is the first description of a negative regulatory region responsive to glucocorticoids in a cytokine gene.

Factors affecting IL-1-mediated collagen metabolism by fibroblasts and the pathogenesis of periodontal disease: a review of the literature

Fibroblasts have been studied extensively for their contribution to connective tissue destruction in diseases where the metabolism of extracellular matrix components plays an essential part in their pathogenesis. A considerable dissolution, especially of collagen fibrils, is a well-known characteristic of the periodontal ligament and the gingival connective tissue in microbial-induced periodontal disease. Fibroblasts, responsible for the assembly of the extracellular matrix, are capable of responding directly to oral microbial challenges or indirectly, following activation of the host immune response, and can alter the composition of connective tissue in several ways: synthesis of inflammatory mediators, their receptors and antagonists; fibroblast proliferation; collagen synthesis; phagocytosis of collagen fibrils; and synthesis of proteolytic enzymes, including matrix metalloproteinases and their corresponding inhibitors. The contributions of these cellular fibroblastic properties to the pathogenesis of periodontal disease are reviewed in the context of the cytokine, interleukin-1, as the inflammatory regulator.

Bacterial endotoxin-induced gene expression in the choroid plexus and paraventricular and supraoptic hypothalamic nuclei of the sheep

The febrile and neuroendocrine responses to circulating endotoxin are effected, at least in part, by a central action of prostaglandins with interleukins serving as intermediaries. Data from rodents suggest that prostaglandin and interleukin (IL-1 beta) synthesis in response to endotoxin challenge may occur within the circumventricular organs of the brain, especially the choroid plexus; the present study investigated this possibility using the sheep as an experimental model. A pyretic dose of bacterial endotoxin (40 micrograms lipopolysaccharide) was given intravenously to sheep (n = 5) and the effect on gene expression in the choroid plexus after a 40 min interval was compared with that observed in vehicle-treated animals (n = 5) using in situ hybridisation histochemistry. Evidence of activational and synthetic events following endotoxin administration was provided by significant increases in c-fos (P < 0.05) and IL-1 beta (P < 0.01) mRNA expression. Constitutive cyclooxygenase (cox-1 mRNA) and inducible cyclooxygenase (cox-2 mRNA) synthesis were unchanged. The investigation also sought to provide evidence for endotoxin effects on neuroendocrine activity in this species by examining changes in hypothalamic gene expression. The results showed that c-fos mRNA increased in the paraventricular (P < 0.01) and supraoptic (P < 0.05) nuclei and that CRH mRNA was upregulated in the paraventricular nucleus (P < 0.001). However, in agreement with previous work, there was no change in vasopressin gene expression although oxytocin mRNA was enhanced throughout the paraventricular nucleus (P < 0.05). These findings suggest the following: (1) possible involvement of the choroid plexus in the response of sheep to immunological challenge: (2) endotoxin-induced changes in gene expression in the ovine hypothalamus similar in those caused by other stressors: and (3) possible changes in oxytocin synthesis concomitant with fever in the sheep.

Interleukin-1 beta induces nuclear factor kappa B in epithelial cells independently of the production of reactive oxygen intermediates

A large body of work has been devoted to tumor necrosis factor alpha or interleukin-1 beta (IL-1 beta) signaling leading to the activation of the transcription factor nuclear factor-kappa B (NF-kappa B) in various cell types. Several studies have indicated that NF-kappa B activation depends strictly on the production of reactive oxygen intermediates. In this report, we first demonstrated that IL-1 beta is a potent activator of NF-kappa B in various epithelial transformed cell lines (OVCAR-3, SKOV-3, MCF7 A/Z). In these cells, IL-1 beta rapidly induces NF-kappa B through a complete degradation of I kappa B-alpha, while H2O2 activates NF-kappa B with slower kinetics through a partial degradation of I kappa B-alpha, p100 and p105. We showed that IL-1 beta-mediated induction of NF-kappa B in OVCAR-3 and in other epithelial cell lines does not proceed through the production of reactive oxygen intermediates, while the same cytokine activates NF-kappa B in lymphoid cells through the intracellular generation of H2O2. Our study demonstrated that several signaling pathways lead to the activation of NF-kappa B, following IL-1 beta treatment in different cell types.

Increased expression of interleukin-1 receptors on fibroblasts derived from inflamed gingiva

We investigated the expression of interleukin-1 receptors (IL-1R) on the surfaces of cultured gingival fibroblasts derived from healthy and inflamed gingiva and the effects of IL-1 alpha and IL-1 beta and prostaglandin E2 (PGE2) on IL-1R expression. Fibroblasts were obtained from explant culture of both healthy and inflamed gingiva. IL-1R on cell surfaces was detected immunohistochemically using an anti-human IL-1R monoclonal antibody. IL-1R expression was assessed quantitatively using an enzyme linked immunosorbent assay (ELISA). Positive staining for IL-1R was more evident on cells from inflamed gingiva compared with cells from healthy gingiva. The ELISA showed a significantly increased number of IL-1R on cells from inflamed gingiva compared with cells from healthy gingiva (P < 0.05). Treatment with IL-1 but not PGE2 increased expression of IL-1R on fibroblasts. These findings suggest that gingival fibroblast responses to IL-1 may represent a mechanism for amplification of gingival inflammation.

Interleukin-1 mediates induction of tolerance to global ischemia in gerbil hippocampal CA1 neurons

A series of experiments was performed to determine the role of interleukin (IL)-1 in the induction of tolerance to global ischemia in Mongolian gerbils. In Group I, a 2-min "preconditioning" ischemia protected CA1 hippocampal neurons in gerbils subjected to 3.5 min ischemia 3 days later. CA1 neuronal density was: sham, 171 +/- 3/mm; 3.5 min ischemia, 30 +/- 30/mm; 2 and 3.5 min ischemia 162 +/- 6/mm. Experiments in Group II addressed the role of IL-1 in the induction of tolerance by sublethal ischemia. Arterial IL-1 alpha and IL-1 beta became elevated between 1 and 3 days after a 2-min ischemic exposure. IL-1 alpha was: sham, 6.4 +/- 0.6 ng/ml; and 2-day, 10.2 +/- 1.2 ng/ml. IL-1 beta was: sham, 6.4 +/- 0.5 ng/ml; and 2-day, 17.3 +/- 2 ng/ml. Recombinant human IL-1 receptor antagonist (IL-1ra) i.p. blocked ischemic tolerance induction by 2-min preconditioning ischemia: 2-min ischemia + vehicle, 162 +/- 6/mm; and 2-min ischemia + IL-1ra, 67 +/- 17/mm. Experiments in Group III assessed the capacity of IL-1 to induce tolerance to brain ischemia. IL-1 alpha i.p. (0, 10, 20 micrograms/kg) for 3 days prior to 3.5-min forebrain ischemia provided significant CA1 neuroprotection in a dose-dependent manner: 2 +/- 2, 68 +/- 83, and 129 +/- 42/mm, respectively. IL-1 beta (15 micrograms/kg) in combination with either IL-1ra (100 mg/kg) or IL-1ra vehicle i.p. on the same schedule demonstrated a significant CA1 neuroprotection that could be nullified by IL-1ra: IL-1 beta + IL-1ra vehicle, 153 +/- 16/mm; and IL-1 beta + IL-1ra, 67 +/- 36/mm. Recognition that tolerance arises from stimulation of a known receptor (IL-1RI) permits molecular analysis of the intracellular signaling that is critical for production of that state.

Expression of interleukin-1 in human pheochromocytoma

Cytokines and in particular interleukin 1 (IL-1) play a role in the micro-environment of various tumors. In addition, it is well established that IL-1 is a neurotrophic, angiogenetic and fibrogenetic factor. Using in situ hybridization we analyzed the expression of endogenous IL-1 in human pheochromocytoma (PCC). With the help of specific antibodies to B- and T-cells, macrophages, and neuroendocrine cell antigens, we characterized the distribution and localization of various cell types in human PCC. The combination of immunohistochemistry and in situ hybridization was eminently suited to defining the exact cellular source of IL-1 expression. In situ hybridization and immunostaining revealed that IL-1 mRNA was located primarily in the tumor cell itself. IL-1 may therefore constitute an important paracrine/autocrine factor in neuroendocrine tumors.

Keratinocytes and cytokine/growth factors

Cytokines are polypeptide growth factors produced by most nucleated cells in the body, including epithelial cells, keratinocytes, and Langerhans cells in the skin. Cytokines can be classified into interleukins, tumor necrosis factors, chemokines, colony-stimulating factor, interferons, and growth factors. Like classic hormones, cytokines bind to specific receptors to transmit their messages to target cells. Cytokine receptors can be divided into three cytokine receptor superfamilies: the immunoglobulin superfamily, the hematopoietin family, and the tumor necrosis factor family. Following cytokine/cytokine-receptor binding (first messenger), a signal transduction pathway is initiated. Factors affecting homeostasis in the skin and oral mucosa include a delicate balance between cytokines/cytokine-receptors and their antagonists. An imbalance in these variables can influence the development of cutaneous and oral diseases-such as lichen planus, autoimmune disorders, and some neoplastic processes- and can affect wound healing. Potential uses of cytokines include cancer and antiviral therapy.

The dynamics of inflammatory cytokines in the healing process of mouse skin wound: a preliminary study for possible wound age determination

The dynamics of inflammatory cytokines such as interleukin-1 alpha (IL-1 alpha), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF alpha) during the healing process of mouse skin wounds were examined using the enzyme-linked immunosorbent assay and immunostaining. The applicability of this examination for wound age estimation is discussed from the perspective of forensic pathology. After wound induction, mice were sacrificed at intervals ranging from 0 to 240 h. The levels of TNF alpha and IL-1 beta began to elevate rapidly after wounding and reached a peak at 3 h. The IL-1 alpha level reached a peak at 6 h, and IL-6 peaked at 12 h. An infiltration of numerous leukocytes, indicating acute inflammation, was observed at 3 and 6 h, and the main source of the cytokines was immunohistochemically identified as neutrophils. These results indicate that TNF alpha and IL-1 beta play an important role in the commencement of inflammation. "Rebound" of cytokine levels, i.e. a re-increase, was observed at 72 h after wounding. Histological examination of the 72-h-old wound showed migration of fibroblasts and the formation of new granulation tissues, indicating the proliferative stage of the wound healing process. These experimental findings indicate that these cytokines have a close relationship to wound remodeling as well as to inflammation. From the viewpoint of forensic pathology, it is considered that inflammatory cytokines may become one of the markers for wound age estimation, but further studies are needed, especially those involving the investigation using human wound specimens with known time intervals after injury.