Production of mice deficient in genes for interleukin (IL)-1alpha, IL-1beta, IL-1alpha/beta, and IL-1 receptor antagonist shows that IL-1beta is crucial in turpentine-induced fever development and glucocorticoid secretion

Hormonal influences in multiple sclerosis

The function of hormones has expanded to include immunomodulation and neuroprotection in addition to their classic roles. The story of how hormones influence inflammation and neuron and glial function is being slowly unraveled. There is increasing evidence that estrogen, progesterone, and testosterone contain immune responses and influence damage repair in the nervous system. Hormones such as prolactin and vitamin D are being explored as immunomodulators and may influence diseases such as multiple sclerosis (MS) or may be used therapeutically to modulate the immune response. More recently identified hormones, such as leptin and gherlin, may also influence the course of disease. This chapter reviews some of the evidence that supports a role for hormones in MS.

Does gamma-aminobutyric acid (GABA) influence the development of chronic inflammation in rheumatoid arthritis?

Background

Recent studies have demonstrated a role for spinal p38 MAP kinase (MAPK) in the development of chronic inflammation and peripheral arthritis and a role for GABA in the inhibition of p38 MAPK mediated effects. Integrating these data suggests that GABA may play a role in downregulating mechanisms that lead to the production of proinflammatory agents such as interleukin-1, interleukin-6, and matrix metalloproteinase 3 – agents implicated in the pathogenesis of rheumatoid arthritis (RA). Genetic studies have also associated RA with members of the p38 MAPK pathway.

Hypothesis

We propose a hypothesis for an inefficient GABA signaling system that results in unchecked proinflammatory cytokine production via the p38 MAPK pathway. This model also supports the need for increasing research in the integration of immunology and neuroscience.

Alteration of behavioural phenotype in mice by targeted disruption of the progranulin gene

Sexual differentiation of the brain in rodents is achieved by estrogens, which are converted from androgens in the brain, during the perinatal period. We have identified the progranulin (PGRN) gene as one of the sex steroid-inducible genes that may be involved in masculinization of the rat brain. In the present study, we generated a line of mice with targeted disruption of the PGRN gene, and investigated male sexual behaviour, aggression and anxiety. PGRN-deficient mice exhibited a decrease in ejaculation incidence, while the latency and frequency of both mount and intromission were unchanged. For the aggressive behaviour test, the resident-intruder paradigm was used, and PGRN-deficient mice exhibited enhanced aggressiveness. In wild-type mice, males exhibited lower levels of anxiety than females by the open field test, while male PGRN-deficient mice exhibited an elevated level of anxiety and sex difference in anxiety was not observed. In addition, mRNA expression of the serotonergic receptor 5-HT1A, which could be related to the inhibition of aggression and anxiety, was significantly reduced in the hippocampus of PGRN-deficient mice after aggressive encounters. On the other hand, deficiency of the PGRN gene did not affect serum testosterone concentrations. These results suggest that PGRN gene plays a role in establishing sexual dimorphic behaviours at least partially by modulating the brain serotonergic system.

Cytokines: Important for implantation?

PROBLEM

Cytokines are obviously very important in an established pregnancy, but what about human embryo implantation?

METHODS

Literature review.

RESULTS

We first discuss the necessity and limits of animal models, and then review the few cytokines which have been demonstrated by knock-out methods to be absolutely necessary for embryo implantation using in animal models. We then review what is known or discussed about the role of other cytokines as deduced from quantitative and/or qualitative dysregulation in animals and in humans.

CONCLUSIONS

Cytokines are indeed involved in implantation as they are in ongoing pregnancy and delivery. Relevance to infertility and recurrent pregnancy loss is discussed.

Knockout mice lacking cPGES/p23, a constitutively expressed PGE2 synthetic enzyme, are peri-natally lethal

Cytosolic prostaglandin (PG) E synthase (cPGES) is constitutively expressed in various cells and regulates cyclooxygenase (COX)-1-dependent immediate PGE(2) generation. Its primary structure is identical to co-chaperone p23, a heat shock protein 90 (Hsp90)-binding protein. We have revealed that Hsp90 regulated both cPGES/p23 and its client protein kinase CK2. In this study, in order to examine the role of cPGES/p23 in vivo, we generated mice deficient in cPGES/p23 by a targeted disruption of exons 2 and 3, containing Tyr9, which is essential for catalytic activity. Heterozygotes are viable, fertile, and appear normal, despite a decrease in cPGES/p23 protein level. A generation of offsprings derived from intercrosses of cPGES/p23 homozygous mice revealed that 109, 247, and 10 pups were wild type, heterozygous, and homozygous, respectively; however, all homozygotes died at birth. The absence of viable null mutants, with heterozygotes and wild-type offspring obtained at a ratio of approximately 2:1, indicated that homozygosity for the cPGES/p23 null mutant leads to peri-natal lethality. Embryos homozygous for cPGES/p23-null had lower body weights than wild-type embryos, and abnormal morphology of skin and lungs. Moreover, the PGE(2) content in the lungs of cPGES/p23-null embryos was lower than that of the wild type. These results indicate that cPGES-derived PGES is involved in the normal development of mouse embryonic lung.

Leptin induces interleukin-1beta release from rat microglial cells through a caspase 1 independent mechanism

Leptin regulates energy balance by suppressing appetite and increasing energy expenditure through actions in the hypothalamus. Recently we demonstrated that the effects of leptin are, at least in part, mediated by the release of interleukin (IL)-1beta in the brain. Microglia constitute the major source of IL-1beta in the brain but it is not known whether these cells express leptin receptors, or respond to leptin to produce IL-1beta. Using RT-PCR and immunocytochemistry, we demonstrate that primary rat microglial cells express the short (non-signalling) and long (signalling) isoforms of the leptin receptors (Ob-R)s. Immunoassays performed on cell medium collected 24 h after leptin treatment (0.01-10 microg/mL) demonstrated a dose-dependent production and release of IL-1beta and its endogenously occurring receptor antagonist IL-1RA. In addition leptin-induced IL-1beta release occurs via a signal transducer and activator of transcription 3 (STAT3)-dependent mechanism. Western blot analysis demonstrated that leptin induced the synthesis of pro-IL-1beta in microglial cells and the release of mature 17 kDa isoform into the culture medium. Leptin-induced IL-1beta release was neither inhibited by the pan-caspase inhibitor BOC-D-FMK, nor by the caspase 1 inhibitor Ac-YVAD-CHO indicating that IL-1 cleavage is independent of caspase activity. These results confirm our earlier observations in vivo and demonstrate that microglia are an important source of IL-1beta in the brain in response to leptin.

TNF-induced structural joint damage is mediated by IL-1

Blocking TNF effectively inhibits inflammation and structural damage in human rheumatoid arthritis (RA). However, so far it is unclear whether the effect of TNF is a direct one or indirect on up-regulation of other mediators. IL-1 may be one of these candidates because it has a central role in animal models of arthritis, and inhibition of IL-1 is used as a therapy of human RA. We removed the effects of IL-1 from a TNF-mediated inflammatory joint disease by crossing IL-1alpha and beta-deficient mice (IL-1-/-) with arthritic human TNF-transgenic (hTNFtg) mice. Development of synovial inflammation was almost unaffected on IL-1 deficiency, but bone erosion and osteoclast formation were significantly reduced in IL-1-/-hTNFtg mice, compared with hTNFtg mice based on an intrinsic differentiation defect of IL-1-deficient monocytes. Most dramatically, however, cartilage damage was absent in IL-1-/-hTNFtg mice. Chimera studies revealed that protection of cartilage is based on the loss of IL-1 on hematopoietic, but not mesenchymal, cells, leading to decreased expression of ADAMTS-5 and MMP-3. These data show that TNF-mediated cartilage damage is completely and TNF-mediated bone damage is partially dependent on IL-1, suggesting that IL-1 is a crucial mediator for inflammatory cartilage and bone degradation.

Inductions of histidine decarboxylase in mouse tissues following systemic antigen challenge: contributions made by mast cells, non-mast cells and IL-1

BACKGROUND

Previous findings suggest that antigen challenge (AC) may induce histidine decarboxylase (HDC) in cells other than mast cells (MCs) via MC-derived IL-1. We examined this hypothesis.

METHODS

Mice were sensitized to ovalbumin. After the sensitization, an AC was delivered intravenously.

RESULTS

In control mice, AC markedly induced HDC at a postanaphylactic time in the liver, lung, spleen, and ears. In MC-deficient W/W(v) mice, AC also induced HDC, although the effect was weaker than in control mice. AC increased IL-1 in the tissues, the pattern being similar in W/W(v) and control mice. AC induced HDC similarly in IL-1-deficient and control mice. In control mice, AC decreased histamine in the tissues (except the liver) for several hours.

CONCLUSION

(1) AC induces HDC in both MC-dependent and MC-independent ways. (2) AC induces IL-1 mostly in non-MCs, but this IL-1 is not a prerequisite for the induction of HDC by AC. (3) HDC induction may contribute to the replenishment of the reduced pool of MC histamine in the anaphylactic period. (4) In the case of MC-dependent HDC induction, AC may stimulate MCs in such a way as to induce HDC within the MCs themselves, and/or AC-stimulated MCs may stimulate HDC induction in other cells, which will need to be directly identified in future studies.

Lipopolysaccharide promotes and augments metal allergies in mice, dependent on innate immunity and histidine decarboxylase

BACKGROUND

Few adequate murine models exist for metal allergies, it being especially difficult to induce Ni allergy in mice.

OBJECTIVE

We examined the effect of lipopolysaccharide (LPS) on allergies to Ni and other metals in mice.

METHODS

Ten days after sensitization with a metal salt and LPS, the ears were challenged with the same metal salt.

RESULTS

LPS+NiCl(2) (1 mM) was effective at sensitizing mice to Ni, LPS being effective at very low concentrations whether injected intradermally or intraperitoneally. The ear-swelling response to Ni was more severe and more rapid in C57BL/6 mice than in BALB/c mice. In mast-cell-deficient mice, TNF-alpha-deficient mice, and interestingly even in nude (T cell deficient) mice, NiCl(2)+LPS induced a Ni allergy similar in degree to that in the respective control mice, but it induced Ni allergy only weakly in TLR4-mutant mice, macrophage-depleted mice, and IL-1-deficient mice. The activity of the histamine-forming enzyme histidine decarboxylase (HDC) in the ears increased in parallel with ear swelling, and HDC-deficient mice were resistant to ear swelling. Challenge with NiCl(2)+LPS augmented ear swelling (vs. NiCl(2) alone). LPS induced effective sensitization to other metals (Cr, Co, Pd, or Ag).

CONCLUSIONS

These results indicate that in mice, LPS is a very important inducer of metal allergies, and potently promotes them (dependent on both innate immunity and HDC induction in cells other than mast cells). We discussed the idea that the bacterial environment is important for the establishment of metal allergies and for their provocation, and that the current thinking (including the contribution of T cells) should be reappraised in future studies.

Intestinal inflammation downregulates smooth muscle CPI-17 through induction of TNF-alpha and causes motility disorders

Motility disorders are frequently observed in intestinal inflammation. We previously reported that in vitro treatment of intestinal smooth muscle tissue with IL-1beta decreases the expression of CPI-17, an endogenous inhibitory protein of smooth muscle serine/threonine protein phosphatase, thereby inhibiting contraction. The present study was performed to examine the pathophysiological importance of CPI-17 expression in the motility disorders by using an in vivo model of intestinal inflammation and to define the regulatory mechanism of CPI-17 expression by proinflammatory cytokines. After the induction of acute ileitis with 2,4,6,-trinitrobenzensulfonic acid, CPI-17 expression declined in a time-dependent manner. This decrease in CPI-17 expression was parallel with the reduction of cholinergic agonist-induced contraction of smooth muscle strips and sensitivity of permeabilized smooth muscle fibers to Ca(2+). Among the various proinflammatory cytokines tested, TNF-alpha and IL-1beta were observed to directly inhibit CPI-17 expression and contraction in cultured rat intestinal tissue. Moreover, both TNF-alpha and IL-1beta inhibited CPI-17 expression and contraction of smooth muscle tissue isolated from wild-type and IL-1alpha/beta double-knockout mice. However, IL-1beta treatment failed to inhibit CPI-17 expression and contraction in TNF-alpha knockout mice. In beta-escin-permeabilized ileal tissues, pretreatment with anti-phosphorylated CPI-17 antibody inhibited the carbachol-induced Ca(2+) sensitization in the presence of GTP. These findings suggest that CPI-17 was downregulated during intestinal inflammation and that TNF-alpha plays a central role in this process. Downregulation of CPI-17 may play a role in motility impairments in inflammation.

Interleukin-1 is not essential for expression of inducible NOS in hepatocytes induced by lipopolysaccharide in vivo

Interleukin (IL)-1 and tumor necrotic factor alpha (TNFalpha) are pivotal in the pathogenesis of endotoxemia. In spite of the in vitro finding that IL-1beta, but not TNFalpha, can induce iNOS mRNA and NO production as a single stimulus in hepatocytes in primary culture, the involvement of IL-1 in iNOS induction in the liver has been less clear in vivo. To address this, we challenged IL-1alpha/beta double-knockout (IL-1alpha/beta(-/-)) and TNFalpha(-/-) mice with lipopolysaccharide (LPS). As compared with wild-type mice, the increases in the plasma NO level measured as nitrite and nitrate and hepatic iNOS were significantly reduced in IL-1alpha/beta(-/-) and TNFalpha(-/-) mice 8 and 12h after the LPS challenge. In the wild-type mice, iNOS protein was first detected in Kupffer cells around the portal vein 2h after LPS challenge; and then it spread to hepatocytes throughout the intralobular region of the liver by 8h. Although the expression of iNOS protein was detected in Kupffer cells of both IL-1alpha/beta(-/-) and TNFalpha(-/-) mice, its level was moderate in hepatocytes of IL-1alpha/beta(-/-) mice, but negligible in those of TNFalpha(-/-) mice, 8h after LPS challenge. Concomitant with the expression of iNOS protein in the liver, Toll-like receptor 4, the signaling receptor for LPS, was expressed in hepatocytes of wild-type and IL-1alpha/beta(-/-) mice, but not of TNFalpha(-/-) mice. These results demonstrate that the expression of Toll-like receptor 4 is well correlated with that of iNOS protein in hepatocytes in vivo after LPS challenge and that IL-1 is not essential for the induction of iNOS in hepatocytes in vivo.

The involvement of IL-1 in tumorigenesis, tumor invasiveness, metastasis and tumor-host interactions

Interleukin-1 (IL-1) includes a family of closely related genes; the two major agonistic proteins, IL-1alpha and IL-1beta, are pleiotropic and affect mainly inflammation, immunity and hemopoiesis. The IL-1Ra antagonist is a physiological inhibitor of pre-formed IL-1. Recombinant IL-1alpha and IL-1beta bind to the same receptors and induce the same biological functions. As such, the IL-1 molecules have been considered identical in normal homeostasis and in disease. However, the IL-1 molecules differ in their compartmentalization within the producing cell or the microenvironment. Thus, IL-1beta is solely active in its secreted form, whereas IL-1alpha is mainly active in cell-associated forms (intracellular precursor and membrane-bound IL-1alpha) and only rarely as a secreted cytokine, as it is secreted only in a limited manner. IL-1 is abundant at tumor sites, where it may affect the process of carcinogenesis, tumor growth and invasiveness and also the patterns of tumor-host interactions. Here, we review the effects of microenvironment- and tumor cell-derived IL-1 on malignant processes in experimental tumor models and in cancer patients. We propose that membrane-associated IL-1alpha expressed on malignant cells stimulates anti-tumor immunity, while secretable IL-1beta, derived from the microenvironment or the malignant cells, activates inflammation that promotes invasiveness and also induces tumor-mediated suppression. Inhibition of the function of IL-1 by the IL-1Ra, reduces tumor invasiveness and alleviates tumor-mediated suppression, pointing to its feasibility in cancer therapy. Differential manipulation of IL-1alpha and IL-1beta in malignant cells or in the tumor's microenvironment can open new avenues for using IL-1 in cancer therapy.

Interleukin-1beta-driven inflammation promotes the development and invasiveness of chemical carcinogen-induced tumors

The role of microenvironment interleukin 1 (IL-1) on 3-methylcholanthrene (3-MCA)-induced carcinogenesis was assessed in IL-1-deficient mice, i.e., IL-1beta(-/-), IL-1alpha(-/-), IL-1alpha/beta(-/-) (double knockout), and mice deficient in the naturally occurring inhibitor of IL-1, the IL-1 receptor antagonist (IL-1Ra). Tumors developed in all wild-type (WT) mice, whereas in IL-1beta-deficient mice, tumors developed slower and only in some of the mice. In IL-1Ra-deficient mice, tumor development was the most rapid. Tumor incidence was similar in WT and IL-1alpha-deficient mice. Histologic analyses revealed fibrotic structures forming a capsule surrounding droplets of the carcinogen in olive oil, resembling foreign body-like granulomas, which appeared 10 days after injection of 3-MCA and persisted until the development of local tumors. A sparse leukocyte infiltrate was found at the site of carcinogen injection in IL-1beta-deficient mice, whereas in IL-1Ra-deficient mice, a dense neutrophilic infiltrate was observed. Treatment of IL-1Ra-deficient mice with recombinant IL-1Ra but not with an inhibitor of tumor necrosis factor abrogated the early leukocytic infiltrate. The late leukocyte infiltrate (day 70), which was dominated by macrophages, was also apparent in WT and IL-1alpha-deficient mice, but was nearly absent in IL-1beta-deficient mice. Fibrosarcoma cell lines, established from 3-MCA-induced tumors from IL-1Ra-deficient mice, were more aggressive and metastatic than lines from WT mice; cell lines from IL-1-deficient mice were the least invasive. These observations show the crucial role of microenvironment-derived IL-1beta, rather than IL-1alpha, in chemical carcinogenesis and in determining the invasive potential of malignant cells.

Mast cells contribute to initiation of autoantibody-mediated arthritis via IL-1

Mast cells are immune sentinels that participate in the defense against bacteria and parasites. Resident within the joint, mast cells become activated in human rheumatoid arthritis and are implicated in the pathogenesis of experimental murine synovitis. However, their arthritogenic role remains undefined. Using a model of autoantibody-induced arthritis, we show that mast cells contribute to the initiation of inflammation within the joint by elaboration of IL-1. Mast cells become activated to produce this cytokine via the IgG immune complex receptor FcgammaRIII. Interestingly, mast cells become dispensable for the perpetuation of arthritis after delivery of IL-1, highlighting the contribution of this lineage to arthritis induction. These findings illuminate a mechanism by which mast cells can participate in the pathogenesis of autoimmune inflammatory arthritis and provide insights of potential relevance to human rheumatoid arthritis.

Reproductive phenotypes in mice with targeted disruption of the 20alpha-hydroxysteroid dehydrogenase gene

In the corpus luteum of rats and mice, 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) catalyzes the conversion of progesterone to a biologically inactive metabolite, 20alpha-dihydroprogesterone (20alpha-OHP). The reduction of progesterone by 20alpha-HSD is believed to be important for functional luteolysis in these rodent species. In addition to the corpus luteum, expression of 20alpha-HSD has been demonstrated in tissues such as the placenta, endometrial epithelia, and fetal skin, although the roles it plays in the latter tissues remain to be determined. To determine the contribution of 20alpha-HSD to functional luteolysis and to the rodent reproductive system more generally, we generated a strain of mice with targeted disruption of the 20alpha-HSD gene. In the 20alpha-HSD-/- mice we obtained, which lacked the genomic region essential for catalytic reaction, neither 20alpha-HSD activity in the corpus luteum nor an increase in the serum concentrations of 20alpha-OHP during pseudopregnancy or pregnancy was detected. The durations of the estrous cycle, pseudopregnancy, and pregnancy were significantly prolonged in the 20alpha-HSD-/- mice, although the serum progesterone levels decreased to levels low enough for delivery of pups at term of pregnancy. In addition, the number of pups, especially live pups, was markedly decreased in the 20alpha-HSD-/- mice. These findings suggest that the role of 20alpha-HSD in functional luteolysis is relatively minor but that it is involved in the survival of newborn mice.

Cytokines and the immune–neuroendocrine network: What did we learn from infection and autoimmunity?

The initial view of the neuroendocrine-immune communication as the brake of immune activation is changing. Recent evidence suggests that the optimization of the body's overall response to infection could be actually the role of the immune-endocrine network. In gradually more complex organisms, the multiplicity of host-pathogen interfaces forced the development of efficient and protective responses. Molecules such as cytokines and Toll-like receptors (TLRs) are distributed both in the periphery and in the brain to participate in a coordinated adaptive function. When sustained release of inflammatory mediators occurs, as in autoimmune diseases, undesirable pathological consequences become evident with different manifestations and outcomes. Clearly, organisms are not well adapted to that disregulated condition yet, suggesting that additional partners within neuroendocrine-immune interactions might emerge from the evolutionary road.

Histidine decarboxylase-stimulating and inflammatory effects of alendronate in mice: Involvement of mevalonate pathway, TNFα, macrophages, and T-cells

Nitrogen-containing bisphosphonates (NBPs) are powerful anti-bone-resorptive drugs, but they frequently induce various inflammatory side effects. Recent clinical applications have disclosed an unexpected new side effect, jaw-bone necrosis and exposure. In vitro studies suggest that the inflammatory effects of NBPs are due to Vgamma2Vdelta2 T-cells, stimulated directly and/or indirectly [the latter via isopentenylpyrophosphate (IPP) in the mevalonate pathway]. Rats and mice, however, lack Vgamma2Vdelta2 T-cells, yet NBPs still induce necrotic and inflammatory reactions. In mice, NBPs induce IL-1-dependent inflammatory reactions, such as inductions of histidine decarboxylase (HDC, the histamine-forming enzyme) in the liver, lung, spleen, and bone marrow, an increase in granulocytic cells in the peritoneal cavity, pleural exudation, and splenomegaly. Here, we examined the involvement of IPP, TNF, macrophages, and T-cells in the inflammatory actions of alendronate (a typical NBP) in mice. Various statins (mevalonate-synthesis inhibitors) suppressed the alendronate-induced HDC inductions, while mevalonate itself augmented such inductions. IPP injection also induced HDC. Like IL-1-deficient mice, TNF-deficient mice were resistant to alendronate-stimulated HDC induction. Alendronate-stimulated HDC inductions were significantly weaker in macrophage-depleted mice and in nude mice than in control mice. Similar, though generally less clear-cut, results were obtained when other alendronate-induced inflammatory reactions were examined. These results suggest that (i) inhibition of the mevalonate pathway causes and/or modifies at least some inflammatory actions of alendronate in mice, (ii) in addition to IL-1, TNF is also involved in the inflammatory actions of alendronate, and (iii) alendronate may act on a variety of cells, including macrophages and T-cells.

Interleukin-1 Receptor Antagonist Induction as an Additional Mechanism for Liver Receptor Homolog-1 to Negatively Regulate the Hepatic Acute Phase Response

The liver receptor homolog-1 (LRH-1) is an orphan nuclear receptor believed to play a key role in bile acid metabolism, cholesterol homeostasis, and intestinal cell crypt renewal. LRH-1 has recently been reported to negatively regulate the hepatic acute phase response by antagonizing, at least in part, the CCAAT/enhancer-binding protein signaling pathway. Here we have shown, using adenovirus-mediated LRH-1 overexpression and gene-silencing experiments, that the interleukin-1 receptor antagonist (IL-1RA) gene is a novel LRH-1 target gene in hepatic cells. Promoter mapping and chromatin immunoprecipitation experiments revealed that LRH-1 regulates IL-1RA gene expression under inflammatory conditions at the transcriptional level via the binding to an LRH-1 response element. Interestingly, IL-1RA induction by an intraperitoneal injection of lipopolysaccharide is significantly lower in LRH-1 heterozygous compared with wild-type mice, demonstrating the contribution of LRH-1 in IL-1RA gene regulation. Finally, RNA interference experiments indicate that LRH-1 blocks the hepatic acute phase response by, at least in part, inducing IL-1RA expression. Taken together, these results lead to the identification of IL-1RA as a novel LRH-1 target gene and demonstrate the existence of multiple mechanisms contributing to the overall anti-inflammatory properties of LRH-1 in hepatic cells.

A new murine model to define the critical pathologic and therapeutic mediators of polymyositis

OBJECTIVE

To establish a new murine model of polymyositis (PM) for the understanding of its pathologic mechanisms and the development of new treatment strategies.

METHODS

C protein-induced myositis (CIM) was induced by a single immunization of recombinant human skeletal C protein in C57BL/6 mice, as well as in CD4-depleted, CD8-depleted, and mutant mice as controls. Some mice were treated with high-dose intravenous immunoglobulin (IVIG) after disease induction. Muscle tissues were examined histologically.

RESULTS

In mice with CIM, inflammation was confined to the skeletal muscles. Histologic examination revealed a common pathologic feature of CIM and PM, involving abundant infiltration of CD8 and perforin-expressing cells in the endomysial site of the injured muscle. Suppression of myositis was achieved by depletion of both CD4 and CD8 T cells. Despite the development of serum anti-C protein antibodies in wild-type mice, severe myositis was induced in mice deficient in B cells. Induction of myositis was suppressed in interleukin-1alpha/beta (IL-1alpha/beta)-null mutant mice, but not in tumor necrosis factor alpha (TNFalpha)-null mutant mice. Use of IVIG, a treatment with proven efficacy in PM, suppressed CIM in the subgroup of treated mice.

CONCLUSION

CIM mimics PM pathologically and clinically. Infiltration of CD8 T cells is the most likely mechanism of muscle injury, and IL-1, but not B cells or TNFalpha, is crucial in the development of CIM. IVIG has therapeutic effects in CIM, suggesting that the effects of IVIG are not mediated by suppression of antibody-mediated tissue injury. This murine model provides a useful tool for understanding the pathologic mechanisms of PM and for developing new treatment strategies.

A novel DNA vaccine targeting macrophage migration inhibitory factor protects joints from inflammation and destruction in murine models of arthritis

OBJECTIVE

Previous studies have demonstrated that neutralization of macrophage migration inhibitory factor (MIF) by anti-MIF antibodies decreases joint inflammation and destruction in a type II collagen-induced arthritis model in mice. The aim of this study was to develop and describe a simple and effective method of active immunization that induces anti-MIF autoantibodies, which may neutralize MIF bioactivity.

METHODS

We developed a MIF DNA vaccine by introducing oligonucleotides encoding a tetanus toxoid (TTX) Th cell epitope into the complementary DNA sequence of murine MIF. Mice were injected with this construct in conjunction with electroporation. The ability of this immunization to inhibit the development of collagen antibody-induced arthritis (CAIA) in BALB/c mice and spontaneous autoimmune arthritis in interleukin-1 receptor antagonist (IL-1Ra)-deficient mice was then evaluated.

RESULTS

Mice that received the MIF/TTX DNA vaccine developed high titers of autoantibodies that reacted to native MIF. Compared with unvaccinated mice, vaccinated mice also produced less serum tumor necrosis factor alpha after receiving an intravenous injection of lipopolysaccharide. In addition, vaccination with MIF/TTX DNA resulted in significant amelioration of both CAIA in BALB/c mice and symptoms of autoimmune arthritis in IL-1Ra-knockout mice.

CONCLUSION

These results suggest that MIF/TTX DNA vaccination may be useful for ameliorating the symptoms of rheumatoid arthritis.

Differential role and tissue specificity of interleukin-1alpha gene expression in atherogenesis and lipid metabolism

OBJECTIVE

We examined the role of IL-1alpha and IL-1beta expressed by bone marrow-derived cells in atherogenesis and lipid metabolism.

METHODS AND RESULTS

We first studied the effect of atherogenic diet on wild-type C57BL/6 IL-1alpha or IL-1beta deficient mice. IL-1alpha KO resulted in a comparatively higher total cholesterol levels, compared to WT and IL-1beta KO mice (398+/-10; 266+/-19; 223+/-13 mg/dl, respectively, p<0.001), due to higher non-HDL cholesterol. Nevertheless, aortic sinus lesion area was 56% lower in IL-1alpha KO (p<0.05) and 50% lower in IL-1beta KO (p=0.08), compared to WT mice. Likewise, SAA levels in IL-1alpha KO mice were markedly lower compared to WT and IL-1beta KO mice (31+/-14; 220+/-33 and 106+/-39 microg/ml, respectively, p<0.001). To study the specific role of bone marrow-derived IL-1, irradiated C57BL/6 mice were transplanted with either IL-1+/+, IL-1alpha-/- or IL-1beta-/- bone marrow cells. Despite similar lipoprotein levels, aortic sinus lesion area was 59% lower in IL-1alpha-/- transplanted (p<0.05) compared to IL-1+/+ transplanted mice. Lesion area in IL-1beta-/- was 33% lower than in IL-1+/+ recipient mice, but it was not statistically significant.

CONCLUSION

We demonstrated that early lesion formation is accelerated specifically by bone marrow-derived IL-1alpha. Furthermore, we showed that the expression of IL-1alpha in cells other than the bone marrow plays a significant role in non-HDL cholesterol metabolism.

IL-1 receptor antagonist in metabolic diseases: Dr Jekyll or Mr Hyde?

Interleukin-1 receptor antagonist (IL-1ra) has been shown to play a crucial role in the prevention of various inflammatory diseases. There is also convincing evidence that IL-1ra is able to counteract inflammatory effects of IL-1 members implicated in insulin resistance and diabetes. However, the use of knock-out animal models provides evidence to the contrary and the role of IL-1ra in obesity-linked anomalies remains controversial. This minireview gets an insight into recent findings on the implication of IL-1ra and its gene polymorphism in diabetes and obesity, discusses the potential dual effects of IL-1ra observed in different models, and comments on future directions.

Disruption of interleukin-18, but not interleukin-1, increases vulnerability to preterm delivery and fetal mortality after intrauterine inflammation

Preterm birth is a major contributor of adverse perinatal outcome. Clinical data suggest that an inflammatory response is important in the process leading to preterm labor. By using a recently introduced mouse model of localized intrauterine lipopolysaccharide-induced inflammation, the effect of interleukin (IL)-18 gene disruption and/or IL-18 neutralization as well as combined IL-1alpha/beta gene disruption on inflammation-induced fetal loss was investigated. The frequency of preterm fetal loss was significantly higher in IL-18 knockout mice (58.9%) and in mice administered IL-18-binding protein (59.7%) compared to wild-type controls (34.7%). The rate of fetal loss was not affected by IL-1alpha/beta gene deficiency (38.7%). Decreased IL-18 protein expression combined with elevated IL-12 protein expression in uterine tissue of IL-18 knockout mice and IL-18-binding protein-treated animals was noticed. These data demonstrate that preterm pregnancy loss in response to intrauterine inflammation was enhanced by disruption of the IL-18 gene and/or IL-18 neutralization, events that may relate to exaggerated Th1 responses because of an increased IL-12/IL-18 ratio.

Low concentration of interleukin-1beta induces FLICE-inhibitory protein-mediated beta-cell proliferation in human pancreatic islets

High glucose concentrations have a dual effect on beta-cell turnover, inducing proliferation in the short-term and apoptosis in the long-term. Hyperglycemia leads to beta-cell production of interleuking (IL)-1beta in human pancreatic islets. Fas, a death receptor regulated by IL-1beta, is involved in glucose-induced beta-cell apoptosis. Fas engagement can be switched from death signal to induction of proliferation when the caspase 8 inhibitor, FLICE-inhibitory protein (FLIP), is active. Here, we show that IL-1beta at low concentrations may participate in the mitogenic actions of glucose through the Fas-FLIP pathway. Thus, exposure of human islets to low IL-1beta concentrations (0.01-0.02 ng/ml) stimulated proliferation and decreased apoptosis, whereas increasing amounts of IL-1beta (2-5 ng/ml) had the reverse effects. A similarly bimodal induction of FLIP, pancreatic duodenal homeobox (PDX)-1, and Pax4 mRNA expression, as well as glucose-stimulated insulin secretion, was observed. In contrast, Fas induction by IL-1beta was monophasic. Low IL-1beta also induced the IL-1 receptor antagonist (IL-1Ra), suppression of which by RNA interference abrogated the beneficial effects of low IL-1beta. The Fas antagonistic antibody ZB4 and small interfering RNA to FLIP prevented low IL-1beta-stimulated beta-cell proliferation. Consistent with our in vitro results, IL-1beta knockout mice displayed glucose intolerance along with a decrease in islet Fas, FLIP, Pax4, and PDX-1 transcripts. These findings indicate that low IL-1beta levels positively influence beta-cell function and turnover through the Fas-FLIP pathway and that IL-1Ra production prevents harmful effects of high IL-1beta concentrations.

Interleukin-1-dependent sequential chemokine expression and inflammatory cell infiltration in ischemia-reperfusion injury

OBJECTIVE

Ischemia-reperfusion injury is known to cause organ failure, but the mechanisms of pathogenesis remain unclear. Inflammation is a factor in tissue destruction in ischemia reperfusion injury, and interleukin (IL)-1 is a key promoter of inflammation.

DESIGN

Prospective, randomized, and controlled study.

SETTING

University laboratory.

SUBJECTS

Male mice 6-8 wks of age, in which genes for IL-1alpha and IL-1beta (IL-1alpha/beta deficient) and IL-1 receptor antagonist (IL-1RA deficient) are deleted by homologous recombination, and wild-type controls on a Balb/c background.

INTERVENTIONS

In this study, the role of IL-1 on inflammatory cascades, including chemokine expression, inflammatory cell infiltration, and tissue destruction, was investigated in 45 mins of unilateral renal ischemic injury using IL-1alpha/beta-deficient mice and IL-1RA-deficient mice. In addition, the effects of IL-1 on chemokine expression in cultured tubular epithelial cells were investigated.

MEASUREMENTS AND MAIN RESULTS

In vivo study revealed that the number of interstitial infiltrated neutrophils and macrophages, which accompanied the increase of the serum levels of keratinocyte-derived chemokine (KC) and macrophage inflammatory protein (MIP)-1alpha, respectively, significantly increased in IL-1RA-deficient mice. The number of interstitial infiltrated neutrophils correlated well with serum levels of KC at 24 hrs after reperfusion, whereas the number of interstitial infiltrated macrophages correlated well with the serum levels of MIP-1alpha and monocyte chemoattractant protein (MCP)-1 at 24 and 48 hrs after reperfusion, respectively. Likewise, in vitro study revealed that stimulation of tubular epithelial cells by IL-1beta and/or H2O2 sequentially induced KC, MIP-1alpha, and MCP-1 in both protein and messenger RNA levels, which is consistent with in vivo results.

CONCLUSION

IL-1-dependent inflammatory cascades, followed by inflammatory cell infiltration and subsequent tissue destruction, may affect pathogenesis of renal ischemia-reperfusion injury.

Six1 and Six4 promote survival of sensory neurons during early trigeminal gangliogenesis

Survival of sensory neurons is tightly regulated in cell-type and developmental-stage-specific manners. The transcriptional regulatory mechanisms underlying this regulation remain to be elucidated. In the present study, we investigated the role of Six1 and Six4 in the development of trigeminal ganglia. Abundant expression of Six1 and Six4 was noted in sensory neurons during early trigeminal gangliogenesis. Loss of both Six1 and Six4 in mice caused severe defects in the trigeminal ganglia, wherein massive apoptosis accompanied by activation of caspase-3 was observed at early but not late stages of gangliogenesis. In Six1(-/-)Six4(-/-) mice, trigeminal sensory neurons were generated, but showed reduced expression of Bcl-x compared with the wild-type mice. Accordingly, neurons from the deficient mice could not survive in culture even in the presence of neurotrophins. Our results suggest a cell-intrinsic role of Six1 and Six4 in the survival of early-generated trigeminal sensory neurons.

Adenoviral delivery of IL-1 receptor antagonist abrogates disease activity during the development of autoimmune arthritis in IL-1 receptor antagonist-deficient mice

Currently available treatments for rheumatoid arthritis (RA) are limited in terms of their long-term effects and their abilities to control disease progression. Interleukin-1 receptor antagonist (IL-1Ra) is a natural inhibitor of the biologic actions of IL-1, which is known to promote inflammation and degeneration of the joint. In this study, we investigated whether human IL-1Ra gene transfer is effective at treating an established experimental arthritis model. A recombinant adenovirus carrying the gene that encode human hIL-1Ra and GFP (Ad.hIL-1Ra/GFP) was administered by intra-articular injection into the ankle joints of the mice with established the IL-1Ra-deficient Balb/cA mice (IL-1Ra(-/-)), which develop spontaneously chronic inflammatory arthropathy. The effects of two injections of Ad.hIL-1Ra/GFP or control virus with no inserted target gene (Ad.GFP) were compared with the effects of PBS injection with respect to the clinical characteristics of arthritis, as determined by articular index scores, histopathological and immunological assays. We further divided the outcomes of Ad.hIL-1Ra/GFP gene therapy in IL-1Ra(-/-) mice according arthritis stage; early stage and chronic stage corresponding to 8 and 15 weeks of age, respectively. Intra-articular injections of Ad.hIL-1Ra/GFP reduced arthritis severity and footpad swelling compared with control groups treated with Ad.GFP or PBS in early stage IL-1Ra(-/-) mice. Moreover, the histopathology of the ankle joints of IL-1Ra(-/-) mice treated with Ad.hIL-1Ra/GFP showed a significant decrease in synovial proliferation and inflammatory cell infiltration, and preserved proteoglycan levels in the joints of early stage IL-1Ra(-/-) mice compared with the control mice. Moreover, Ad.hIL-1Ra/GFP treated mice showed reduced levels of inflammatory T helper type 1 (Th1) driven IgG2a antibodies to collagen type II but increased levels Th2 driven IgG1 antibody. These results suggest that adenovirus-mediated gene transfer of IL-1Ra may be a promising therapeutic option in the early stage of autoimmune arthritis.

Monocyte/macrophage dysfunctions do not impair the promotion of myelofibrosis by high levels of thrombopoietin

Several lines of evidence indicate that the megakaryocyte/platelet lineage is crucial in myelofibrosis induction. The demonstration that NOD/SCID mice with functionally deficient monocytes do not develop fibrotic changes when exposed to thrombopoietin (TPO) also suggests an important role for monocyte/macrophages. However, in this animal model, the development of myelofibrosis is dependent on the level of TPO. This study was conducted to investigate whether NOD/SCID mice exposed to high TPO levels mediated by a retroviral vector would be refractory to the development of bone marrow fibrosis. We show that TPO and TGF-beta1 in plasma from NOD/SCID and SCID mice engrafted with TPO-overexpressing hemopoietic cells reach levels similar to the ones reached in immunocompetent mice, and all animals develop a myeloproliferative disease associated with a dense myelofibrosis at 8 wk posttransplantation. Monocytes in NOD/SCID mice are functionally deficient to secrete cytokines such as IL-1alpha in response to stimuli, even under TPO expression. Surprisingly, the plasma of these mice displays high levels of IL-alpha, which was demonstrated to originate from platelets. Together, these data suggest that completely functional monocytes are not required to develop myelofibrosis and that platelets are able, under TPO stimulation, to synthesize inflammatory cytokines, which may be involved in the pathogenesis of myelofibrosis and osteosclerosis.

The effect of interleukin-1 receptor antagonist on arteries and cholesterol metabolism

This review summarizes both the structure and function of IL-1 receptor antagonist (IL-1Ra), and relates our new findings, particularly those obtained in IL-1Ra-deficient mice (IL-1Ra(-/-)), to the role of IL-1Ra in arterial diseases and cholesterol metabolism. IL-1Ra(-/-) mice show an increase in neointima-formation after arterial injury. Heterozygosity in the IL-1Ra gene against the apolipoprotein E-deficient background revealed a role for IL-1 in promoting atherogenic cell signaling and that the larger lesions of IL-1Ra(-/-) mice are enriched in macrophages and depleted of smooth muscle cells. Furthermore, IL-1Ra(-/-) mice developed severe fatty livers and hypercholesteroremia following 20 weeks on a atherogenic diet compared to WT mice. Taken together, these results suggest that IL-1Ra plays important roles in restenosis after angioplasty, the development of atherosclerosis, and the metabolism of cholesterol in vivo.

Interleukin-17 acts independently of TNF-alpha under arthritic conditions

The proinflammatory T cell cytokine IL-17 is a potent inducer of other cytokines such as IL-1 and TNF-alpha. The contribution of TNF in IL-17-induced joint inflammation is unclear. In this work we demonstrate using TNF-alpha-deficient mice that TNF-alpha is required in IL-17-induced joint pathology under naive conditions in vivo. However, overexpression of IL-17 aggravated K/BxN serum transfer arthritis to a similar degree in TNF-alpha-deficient mice and their wild-type counterparts, indicating that the TNF dependency of IL-17-induced pathology is lost under arthritic conditions. Also, during the course of the streptococcal cell wall-induced arthritis model, IL-17 was able to enhance inflammation and cartilage damage in the absence of TNF. Additional blocking of IL-1 during IL-17-enhanced streptococcal cell wall-induced arthritis did not reduce joint pathology in TNF-deficient mice, indicating that IL-1 is not responsible for this loss of TNF dependency. These data provide further understanding of the cytokine interplay during inflammation and demonstrate that, despite a strong TNF dependency under naive conditions, IL-17 acts independently of TNF under arthritic conditions.

Interleukin-1beta and signaling of interleukin-1 in vascular wall and circulating cells modulates the extent of neointima formation in mice

Interleukin (IL)-1 is an important mediator of inflammation and cardiovascular disease. Here, we examined the role of IL-1 in arterial neointima formation. Carotid artery neointima was induced by ligation, and arteries were harvested 4 weeks after injury. The neointima/media of mice deficient in the IL-1 signaling receptor (IL-1R1(-/-)) was significantly reduced compared to IL-1R1(+/+) controls (P < 0.01). IL-1R1(+/+) mice receiving subcutaneous IL-1ra also had significantly reduced neointima/media compared with placebo (P < 0.05). IL-1beta(-/-) mice had reduced neointima/media compared to wild-type (P < 0.05), whereas IL-1alpha(-/-) mice were no different from controls. Mice deficient in the P2X(7) receptor (involved in IL-1 release) or caspase-1 (involved in IL-1 activation) did not differ in their response to carotid ligation compared to controls. To examine the site of IL-1 signaling, we generated chimeric mice. IL-1R1(+/+) mice receiving IL-1R1(-/-) marrow and IL-1R1(-/-) mice receiving IL-1R1(+/+) marrow both had significantly reduced neointima/media compared with IL-1R1(+/+) to IL-1R1(+/+) (P < 0.05) but had significantly greater neointima/media than IL-1R1(-/-) to IL-1R1(-/-) controls (P < 0.05). These data confirm the importance of IL-1beta signaling in mediating arterial neointima formation and suggest the involvement of IL-1 signaling in both circulating and arterial wall cells. Furthermore, receptor antagonism may be a better therapeutic target than interruption of IL-1beta processing or release.

Critical Roles of Muscle-Secreted Angiogenic Factors in Therapeutic Neovascularization

The discovery of bone marrow–derived endothelial progenitors in the peripheral blood has promoted intensive studies on the potential of cell therapy for various human diseases. Accumulating evidence has suggested that implantation of bone marrow mononuclear cells effectively promotes neovascularization in ischemic tissues. It has also been reported that the implanted cells are incorporated not only into the newly formed vessels but also secrete angiogenic factors. However, the mechanism by which cell therapy improves tissue ischemia remains obscure. We enrolled 29 “no-option” patients with critical limb ischemia and treated ischemic limbs by implantation of peripheral mononuclear cells. Cell therapy using peripheral mononuclear cells was very effective for the treatment of limb ischemia, and its efficacy was associated with increases in the plasma levels of angiogenic factors, in particular interleukin-1β (IL-1β). We then examined an experimental model of limb ischemia using IL-1β–deficient mice. Implantation of IL-1β–deficient mononuclear cells improved tissue ischemia as efficiently as that of wild-type cells. Both wild-type and IL-1β–deficient mononuclear cells increased expression of IL-1β and thus induced angiogenic factors in muscle cells of ischemic limbs to a similar extent. In contrast, inability of muscle cells to secrete IL-1β markedly reduces induction of angiogenic factors and impairs neovascularization by cell implantation. Implanted cells do not secret angiogenic factors sufficient for neovascularization but, instead, stimulate muscle cells to produce angiogenic factors, thereby promoting neovascularization in ischemic tissues. Further studies will allow us to develop more effective treatments for ischemic vascular disease.

Neuroprotective actions of endogenous interleukin-1 receptor antagonist (IL-1ra) are mediated by glia

The pro-inflammatory cytokine interleukin-1 (IL-1), contributes to neuronal inflammation and cell death induced by ischemia, excitotoxicity, or trauma, while administration of IL-1 receptor antagonist (IL-1ra) reduces neuronal injury. The aim of the present study was to test the hypothesis that endogenous IL-1ra is neuroprotective in vivo and in vitro, and to identify its mechanism of actions. Mice lacking IL-1ra (IL-1ra knock-out (KO]) exhibited a dramatic increase in neuronal injury (3.6-fold increase in infarct size) induced by transient cerebral ischemia compared to wild-type (WT) animals. Basal cell death of cultured cortical neurons from WT and IL-1ra KO was identical, and treatment with NMDA or AMPA (20 microM) increased cell death to the same extent in WT and IL-1ra KO neurons. However, basal and NMDA- or AMPA-induced cells death was significantly higher in glial-neuronal co-cultures from IL-1ra KO than from WT mice. We further showed that pure microglial cultures, but not pure astrocytes cultures, released IL-1ra in response to treatment with conditioned medium from NMDA- or AMPA-treated primary neurons. These results demonstrate that endogenous IL-1ra produced by microglia is neuroprotective in cerebral ischemia or excitotoxicity.

Combined interleukin-6 and interleukin-1 deficiency causes obesity in young mice

Proinflammatory cytokines including interleukin (IL)-1 and IL-6 exert pleiotropic effects on the neuro-immuno-endocrine system. Previously, we showed that IL-1 receptor antagonist-deficient (IL-1Ra(-/-)) mice show a lean phenotype due to an abnormal lipid metabolism. On the contrary, it was reported that IL-6(-/-) mice exhibit obesity after 6 months of age. This study sought to assess the roles of IL-1 and IL-6 in body weight homeostasis. We generated mice deficient in IL-6 and IL-1Ra (IL-6(-/-) IL-1Ra(-/-)) and IL-6, IL-1alpha, and IL-1beta (IL-6(-/-) IL-1(-/-)). IL-6(-/-) IL-1Ra(-/-) mice exhibited a lean phenotype, similar to IL-1Ra(-/-) mice. On the other hand, IL-6(-/-) IL-1(-/-) mice became obese as early as 10 weeks of age, while IL-1(-/-) mice and IL-6(-/-) mice were normal at this age. The daily food intake was significantly higher in IL-6(-/-) IL-1(-/-) mice than in IL-6(-/-) IL-1(+/-) mice, while energy expenditure was comparable in these two strains. Acute anorexia induced by peripheral administration of IL-1 was significantly suppressed in IL-6(-/-) IL-1(-/-) mice, but not in IL-1(-/-) mice or IL-6(-/-) mice compared with wild-type mice. These results indicate that IL-1 and IL-6 are both involved in the regulation of body fat in a redundant manner in young mice.

IL-1beta, but not IL-1alpha, is required for antigen-specific T cell activation and the induction of local inflammation in the delayed-type hypersensitivity responses

As IL-1 expression is augmented in delayed-type hypersensitivity (DTH) responses, we analyzed the role of IL-1 in this response. DTH responses against methyl BSA (mBSA) were significantly suppressed in IL-1beta-deficient (IL-1beta-/-) and IL-1alpha/beta-/- mice, but not in IL-1alpha-/- mice. In contrast, responses in IL-1R antagonist-/- (IL-1Ra-/-) mice were exacerbated. Lymph node cells derived from mBSA-sensitized IL-1beta-/-, IL-1alpha/beta-/- and IL-1R type I (IL-1RI)-/- mice, but not from IL-1alpha-/- mice, exhibited reduced proliferative responses against mBSA, while these from IL-1Ra-/- mice demonstrated augmented responses. DTH responses in wild-type mice following adoptive transfer of CD4+ T cells from mBSA-sensitized IL-1alpha/beta-/- mice were also reduced, while those in mice given cells derived from IL-Ra-/- mice were increased. DTH responses in IL-1RI-/-, but not IL-1alpha/beta-/-, mice were reduced upon transplantation of mBSA-sensitized CD4+ T cells from wild-type mice. The recall response of mBSA-sensitized CD4+ T cells against mBSA decreased upon co-culture with dendritic cells (DCs) from IL-1RI-/- mice, while the responses were normal with DCs from IL-1alpha/beta-/- mice. DTH responses in tumor necrosis factor alpha-/- (TNF-/-) mice were also suppressed; the magnitude of the suppression in IL-1alpha/beta-/-TNF-/- mice, however, was similar to that observed in IL-1alpha/beta-/- mice. These observations indicate that IL-1 possesses dual functions during the DTH response. IL-1beta is necessary for the efficient priming of T cells. In addition, CD4+ T cell-derived IL-1 plays an important role in the activation of DCs during the elicitation phase, resulting in the production of TNF, that activate allergen-specific T cells.

CD28-dependent differentiation into the effector/memory phenotype is essential for induction of arthritis in interleukin-1 receptor antagonist-deficient mice

OBJECTIVE

Interleukin-1 receptor antagonist (IL-1Ra)-deficient mice on a BALB/c background spontaneously develop a chronic inflammatory polyarthropathy closely resembling that of rheumatoid arthritis in humans. To elucidate the role of CD28 costimulatory signals in the development of this disease, we studied IL-1Ra/CD28-double-deficient mice.

METHODS

We crossed IL-1Ra-deficient mice with CD28-deficient mice and observed the incidence and severity of arthritis. To investigate functions of IL-1Ra/CD28-double-deficient T cells, cells were stimulated with CD3 monoclonal antibody or allogeneic antigen-presenting cells (APCs) and their proliferative responses and levels of cytokine production were measured.

RESULTS

Disease severity was lower in IL-1Ra/CD28-double-deficient mice than in mice that were deficient only in IL-1Ra, although incidence of arthritis was not affected by the presence or absence of CD28. When pathogenic IL-1Ra-KO T cells were transferred into nude mice, severe arthritis developed. Even though T cells from double-deficient mice showed the same diminished proliferative capacity as was seen in T cells from CD28-single-deficient animals, nude mice into which double-deficient T cells were transferred never developed arthritis.

CONCLUSION

These findings indicate that IL-1Ra/CD28-double-deficient T cells can be activated by IL-1Ra-deficient activated APCs, resulting in induction of arthritis; however, these T cells did not induce the disease under normal conditions, because they did not differentiate into effector/memory phenotype.

Effects of micro-environment- and malignant cell-derived interleukin-1 in carcinogenesis, tumour invasiveness and tumour-host interactions

Interleukin-1 (IL-1) comprises a family of closely related genes; the two major agonistic proteins, IL-1alpha and IL-1beta, are pleiotropic and affect mainly inflammation, immunity and haemopoiesis. IL-1beta is active solely in its secreted form, whereas IL-1alpha is active mainly as an intracellular precursor. IL-1 is abundant at tumour sites, where it may affect the process of carcinogenesis, tumour growth and invasiveness and the patterns of tumour-host interactions. Here, we review the effects of micro-environment- and tumour cell-derived IL-1 on malignant processes in experimental tumour models. We propose that membrane-associated IL-1alpha expressed on malignant cells stimulates anti-tumour immunity, while secretable IL-1beta derived from the micro-environment or the malignant cells, activates inflammation that promotes invasiveness and induces tumour-mediated suppression. Inhibition of the function of IL-1 by the inhibitor of IL-1, interleukin-1 receptor antagonist (IL-1Ra), reduces tumour invasiveness and alleviates tumour-mediated suppression, pointing to its feasible use in cancer therapy. Differential manipulation of IL-1alpha and IL-1beta in malignant cells or in the tumour's micro-environment may open new possibilities for using IL-1 in cancer immunotherapy.

Involvement of tumor necrosis factor-alpha in the development of T cell-dependent aortitis in interleukin-1 receptor antagonist-deficient mice

BACKGROUND

Interleukin-1 receptor antagonist-deficient (IL-1Ra(-/-)) mice on the BALB/c background spontaneously develop inflammatory arthropathy that resembles rheumatoid arthritis in humans. These mice also frequently develop aortitis at the root of the aorta, but the mechanism underlying the development of this disease has not been completely elucidated.

METHODS AND RESULTS

Using IL-1Ra(-/-) mice (backcrossed 8 generations to the BALB/c background) and wild-type mice, we studied the histopathology and examined the immunologic mechanisms involved in the development of aortic inflammation by cell transplantation experiments. Half of the IL-1Ra(-/-) mice developed aortitis at the root of the aorta, with massive infiltration of macrophages and monocytes and loss of elastic lamellae in the aortic media. Left ventricular hypertrophy and mild aortic stenosis were also shown by transthoracic echocardiography. Transplantation of T cells from IL-1Ra(-/-) mice induced aortitis in recipient nu/nu mice. Bone marrow cell transplants from IL-1Ra(-/-) mice also induced aortitis in irradiated wild-type recipient mice. Furthermore, tumor necrosis factor (TNF)-alpha deficiency completely suppressed the development of aortitis in IL-1Ra(-/-) mice, whereas IL-6 deficiency did not affect pathology.

CONCLUSIONS

These observations suggest that IL-1Ra deficiency in T cells activates them excessively, resulting in the development of aortitis in IL-1Ra(-/-) mice in a TNF-alpha-dependent manner.

Induction of IL-1, in the Testes of Adult Mice, Following Subcutaneous Administration of Turpentine

PROBLEM

Interleukin-1 family is present in the testicular homogenates and its cellular compartments. It has been suggested that IL-1 is involved in physiological and pathological functions of the testicular tissues. In the present study we examined the effect of acute mostly localized inflammation, using turpentine, on the expression levels of testicular IL-1 system.

METHODS OF STUDY

Mice were subcutaneously injected with steam-distilled turpentine or saline (control). Three hours to 10 days following the injection, mice were killed and testis and spleen were homogenized and examined for interleukin (IL)-1alpha, IL-1beta, and IL-1 receptor antagonist (IL-1ra) levels by enzyme-linked immunosorbent assay and polymerase chain reaction.

RESULTS

Subcutaneous injection of turpentine induced mice systemic inflammation, as indicated by significant increase in serum IL-1beta levels, and IL-1alpha, IL-1beta and IL-1ra in spleen homogenates. The levels of IL-1alpha, IL-1beta and IL-1ra were significantly induced in testicular homogenates of adult mice following subcutaneous injection of turpentine. The significant induction of testicular IL-1alpha was detected after 3-24 hr of turpentine injection and decreased later (after 3-10 days) to levels similar to the control. However, significant induction of testicular IL-1beta was detected only after 3-10 days of turpentine injection, and for testicular IL-1ra levels was detected after 3 hr to 6 days of turpentine injection, and after 10 days the levels were similar to the control. These results were also confirmed by mRNA expression of these factors.

CONCLUSION

Our results demonstrate for the first time the distant effect of acute localized inflammation on testicular IL-1 levels. Thus, transient inflammatory response to infectious/inflammatory agents at non-testicular sites that elicit systemic IL-1 response should be considered during clinical treatment as a possible factor of male infertility.

Endotoxin preconditioning protects neurones from in vitro ischemia: role of endogenous IL-1beta and TNF-alpha

We have examined whether changes in the expression of several inflammatory factors mediate the neuroprotective action of LPS preconditioning on cerebellar granule neurones (CGN) exposed to the mitochondrial toxin 3-nitropropionic acid (3-NP), chosen as an in vitro ischemic model. CGN were either directly pre-treated with LPS or indirectly by exposure to conditioned medium (CM) from LPS-treated mixed glial cultures obtained from wild type or IL-1beta-knock out mice. Following this pre-treatment CGN were incubated with 3-NP and cell viability assessed. Our results show that LPS preconditioning in neurones, promotes neuronal survival against 3-NP-induced cell death and that endogenous TNF-alpha is a critical mediator for the neuroprotective actions of LPS independently of the presence of endogenous IL-1beta after 3-NP exposure.

Abnormal T cell activation caused by the imbalance of the IL-1/IL-1R antagonist system is responsible for the development of experimental autoimmune encephalomyelitis

IL-1 is a pro-inflammatory cytokine that plays an important role in inflammation and host responses to infection. We have previously shown that imbalances in the IL-1 and IL-1R antagonist (IL-1Ra) system cause the development of inflammatory diseases. To explore the role of the IL-1/IL-1Ra system in autoimmune disease, we analyzed myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) in mice bearing targeted disruptions of the IL-1alpha, IL-1beta, IL-1alpha and IL-1beta (IL-1) or IL-1Ra genes. IL-1alpha/beta double-deficient (IL-1-/-) mice exhibited significant resistance to EAE induction with a significant reduction in disease severity, while IL-1alpha-/- or IL-1beta-/- mice developed EAE in a manner similar to wild-type mice. IL-1Ra-/- mice also developed MOG-induced EAE normally with pertussis toxin (PTx) administration. In contrast to wild-type mice, however, these mice were highly susceptible to EAE induction in the absence of PTx administration. We found that both IFN-gamma and IL-17 production and proliferation were reduced in IL-1-/- T cells upon stimulation with MOG, while IFN-gamma, IL-17 and tumor necrosis factor-alpha production and proliferation were enhanced in IL-1Ra-/- T cells. These observations suggest that the IL-1/IL-1Ra system is crucial for auto-antigen-specific T cell induction and contributes to the development of EAE.

Comparative appraisal of clodronate, aspirin and dexamethasone as agents reducing alendronate-induced inflammation in a murine model

Among the bisphosphonates, the nitrogen-containing bisphosphonates have much stronger anti-bone-resorptive activities than bisphosphonates containing no nitrogen, but nitrogen-containing bisphosphonates mostly have inflammatory side effects. Our previous murine-model experiments with a single intraperitoneal bisphosphonate injection demonstrated that (i) nitrogen-containing bisphosphonates induce various inflammatory reactions via an IL-1-dependent mechanism, (ii) alendronate (an nitrogen-containing bisphosphonate) produces a clear sclerotic line in the tibia that is easily detectable by radiography a few weeks later (tentatively called the bisphosphonate line, a useful marker for the anti-bone-resorptive activities of bisphosphonates), and (iii) clodronate (a non-nitrogen-containing bisphosphonate) reduces the inflammatory reactions induced by alendronate but does not reduce the bisphosphonate line formation induced by alendronate. We compared the effects of clodronate, aspirin and dexamethasone on the inflammatory reactions induced by alendronate (40 micromol/kg) (induction of the histamine-forming enzyme, accumulation of pleural exudate and splenomegaly) and on the bisphosphonate line formation induced by alendronate (0.1 micromol/kg). The effects of aspirin (833 micromol/kg) were weak. However, like clodronate, dexamethasone (10 micromol/kg, injected 5 min. after alendronate), strongly inhibited the alendronate-induced inflammatory reactions but did not reduce the alendronate-induced bisphosphonate line formation. Alendronate produced normal bisphosphonate lines in IL-1-deficient mice, too. These results suggest that clodronate and/or dexamethasone may be suitable for preventing or reducing the inflammatory side effects of nitrogen-containing bisphosphonates while preserving their powerful anti-bone-resorptive activities (although in practice the known side effects of dexamethasone may limit its use), and that the anti-bone resorptive activities of nitrogen-containing bisphosphonates are not influenced by IL-1.

Early increase in mRNA levels of pro-inflammatory cytokines and their interactions in the mouse hippocampus after transient global ischemia

There is convincing evidence that cytokines are involved in the inflammatory response following cerebral ischemia, but the interactions among the pro-inflammatory cytokines tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-6 in the early stage of ischemic reperfusion are not yet completely understood. In this study, we examined the early mRNA expressions of pro-inflammatory cytokines in the ischemic hippocampus after 30 min of bilateral common carotid artery occlusion in C57BL/6J wild-type (WT) and TNF-alpha, IL-1alpha/beta or IL-6 gene knockout (KO) mice utilizing real-time polymerase chain reaction. The mRNA expressions of the pro-inflammatory cytokines TNF-alpha, IL-6 and IL-1beta were significantly induced in ischemic WT mice compared with in the sham-operated mice. These increases peaked at 3 to 24 h for TNF-alpha, at 12 h for IL-1beta, and at 6 to 24 h for IL-6 after ischemia. The pattern of temporal expression of the cytokine mRNAs in ischemic gene KO mice, however, differed from that in WT mice. The TNF-alpha mRNA expression showed a similar temporal expression pattern in IL-6 KO mice compared to in WT mice following ischemic reperfusion, and the levels at all time points were lower than in WT mice. The IL-1beta mRNA level was very low in ischemic TNF-alpha KO mice and IL-6 KO mice in spite of a small peak observed in both at 24 h. The IL-6 mRNA level was significantly upregulated at all time points in both ischemic WT and TNF-alpha KO mice; however, the peak was delayed by 12-h in IL-1alpha/beta KO mice. In conclusion, the present study indicates that the rapid increases in cytokine levels are interdependent, interactive, and possibly modulate each other in the mouse hippocampus after transient global ischemia.

Fas Ligand Induces Cell-Autonomous IL-23 Production in Dendritic Cells, a Mechanism for Fas Ligand-Induced IL-17 Production

Fas ligand (FasL) has the potential to induce inflammation accompanied by massive neutrophil infiltration. We previously reported that FasL rapidly induces the production of various inflammatory cytokines including IL-1beta and IL-17. In this study, we investigated the mechanism of the FasL-induced IL-17 production. We found that the culture supernatant of mouse resident peritoneal exudate cells (PEC) cocultured with FasL-expressing tumor (FFL) cells induced IL-17 production in freshly isolated resident PEC. Anti-IL-1beta Ab strongly inhibited the IL-17-inducing activity. However, rIL-1beta by itself induced only weak IL-17 production. Intriguingly, anti-IL-12 Ab but not an IL-15-neutralizing agent, IL15R-Fc, strongly inhibited the FasL-induced IL-17-inducing activity. IL-23, which shares the p40 subunit with IL-12, but not IL-12 itself, induced IL-17 production synergistically with IL-1beta in resident PEC. FasL induced the production of IL-23 in PEC in vivo and in vitro, and IL-17 production following the i.p. injection of FFL cells was severely impaired in p40-/- mice, indicating that IL-23 plays an important role in the FasL-induced IL-17 production. FFL also induced the production of IL-23 in bone marrow- or PEC-derived dendritic cells (DCs). Finally, FasL induced only weak p40 production in a mixture of p40-/- and Fas-/- DC, indicating that FasL induces IL-23 production in DC mainly in a cell-autonomous manner.

Adipose tissue: a regulator of inflammation

Adipose tissue is a highly active organ. In addition to storing calories as triglycerides, it also secretes a large variety of proteins, including cytokines, chemokines and hormone-like factors, such as leptin, adiponectin and resistin. Intriguingly, many, if not most, of these adipose-derived proteins have dual actions; cytokines have both immunomodulatory functions and act as systemic or auto-/paracrine regulators of metabolism, while proteins such as leptin and adiponectin are regulators of both metabolism and inflammation. The production of pro-atherogenic chemokines by adipose tissue is of particular interest since their local secretion, e.g. by perivascular adipose depots, may provide a novel mechanistic link between obesity and the associated vascular complications.

Involvement of corticotropin-releasing hormone- and interleukin (IL)-6-dependent proopiomelanocortin induction in the anterior pituitary during hypothalamic-pituitary-adrenal axis activation by IL-1alpha

IL-1alpha/beta and IL-6 are endogenous modulator of hypothalamo-pituitary-adrenal axis (HPAA) and are thought to play key roles in immune-neuroendocrine interactions during inflammation. Here, we show IL-1alpha induced a normal HPAA activation in IL-1alpha/beta knockout (KO) and IL-6 KO mice at 1 h; however, at 6 h HPAA activation was reduced relative to wild-type mice, indicating a role for endogenous IL-1alpha/beta and IL-6 in prolonged HPAA activation. We found that the induction of proopiomelanocortin (POMC) transcript in the anterior pituitary (AP) at 6 h in response to IL-1alpha was reduced in IL-1alpha/beta KO and IL-6 KO mice, as well as in CRH KO mice, suggesting IL-1alpha/beta, IL-6, and CRH are all required for POMC induction. The induction of CRH transcript in the paraventricular nucleus at 6 h and plasma IL-6 levels, in response to IL-1alpha, were reduced in IL-1alpha/beta KO mice. Because IL-1alpha-induced activation of signal transducer and activator of transcription 3 in the AP was also suppressed in IL-6 KO mice, we suggest that plasma IL-6 is first induced by IL-1alpha, and IL-6 activates signal transducer and activator of transcription 3 in the AP, leading to the induction of POMC in concert with CRH. Our results suggest a role for IL-1alpha/beta in the induction of POMC in the AP through the induction of two independent pathways, CRH and IL-6.

Crucial roles of mesodermal cell lineages in a murine embryonic stem cell-derived in vitro liver organogenesis system

Recent studies in the field of regenerative medicine have exploited the pluripotency of embryonic stem (ES) cells to generate a variety of cell lineages. However, the target has always been only a single lineage, which was isolated from other differentiated cell populations. In the present study, we selected sublines with a high capability for differentiation to contracting cardiomyocytes and also produced germ-line chimeric mice from a parent ES line. We also succeed in establishing embryoid bodies prepared from the ES cells that differentiated into not only hepatocytes but also at least two mesodermal lineages: cardiomyocytes that supported liver development and endothelial cells corresponding to sinusoids. This allowed the development of an in vitro system using murine ES cells that approximated the events of liver development in vivo. The expression of albumin was significantly higher in cardiomyocytes that had arisen in differentiated ES cells than in those that had not. Our in vitro system for liver organogenesis consists of a blood/sinusoid vascular-like network and hepatocyte layers and shows higher levels of hepatic function, such as albumin production and ammonia degradation, than hepatic cell lines and primary cultures of murine adult hepatocytes. This innovative system will lead to the development of second-generation regenerative medicine techniques using ES cells and is expected to be useful for the development of bioartificial liver systems and drug-metabolism assays.