Interleukin-1 Receptor Antagonist Knockout Mice Research Articles

S100A8/A9 is not essential for the development of inflammation and joint pathology in interleukin-1 receptor antagonist knockout mice

BackgroundExcessive osteoclast activity, which is strongly stimulated by pro-inflammatory mediators, results in bone and cartilage degeneration as central features of many arthritides. Levels of the alarmin S100A8/A9 and interleukin (IL)-1β are both increased in arthritis patients and correlate with disease activity and progression of tissue erosion. We previously presented S100A8/A9 as a good biomarker for joint inflammation and arthritis pathology under circumstances of high IL-1 signaling in mice that lack the gene encoding IL-1 receptor antagonist (Il1rn−/− mice). Here, we investigated whether S100A8/A9 is also actively involved in the development of joint inflammation and both cartilage and bone pathology under these conditions by comparing Il1rn−/− mice with mice that have an additional deficiency for S100a9 (Il1rn−/−XS100a9−/−).MethodsIl1rn−/−XS100a9−/− on a BALB/c background were obtained by crossing S100a9−/− mice and Il1rn−/− mice. Arthritis incidence and severity were macroscopically scored. Myeloid cell populations in the bone marrow and spleen were determined using flow cytometry. In vitro osteoclastogenesis of bone marrow cells was evaluated with TRAP staining. Microscopic joint inflammation, cartilage degeneration, and bone destruction were evaluated using histology of ankle joints of 12- and 20-week-old mice.ResultsMacroscopically scored arthritis severity was comparable between Il1rn−/− and Il1rn−/−XS100a9−/− mice. Inflammation, cartilage erosion, and bone erosion were clearly present in 12-week-old mice of both strains lacking Il1rn−/−, but not significantly different between Il1rn−/−XS100a9−/− and Il1rn−/−. Moreover, we observed that the numbers of neutrophils and monocytes were increased by the absence of Il1rn, which was affected by the absence of S100a9 only in the spleen but not in the bone marrow. In line with our other findings, the absence of S100a9 did not affect the osteoclastogenic potential of osteoclast precursors in the absence of Il1rn. Finally, in agreement with the findings in early arthritis development in 12-week-old mice, cartilage and bone erosion in 20-week-old mice was significantly higher in both Il1rn−/− strains, but the additional absence of S100a9 did not further affect tissue pathology.ConclusionS100A8/A9 deficiency does not significantly affect inflammation and joint destruction in mice with high IL1β signaling suggesting that S100A8/A9 is not essential for the development of arthritis under these conditions.

Extracellular microvesicles that originated adipose tissue derived mesenchymal stem cells have the potential ability to improve rheumatoid arthritis on mice.

IntroductionMesenchymal stem cells (MSCs) are promising therapeutic tools in regenerative medicine. In particularly adipose tissue derived MSC (AMSC) has powerful potential for the therapeutics of rheumatoid arthritis (RA) because these cells can control immune balance. RA systemically occurs autoimmune disease. Interestingly, IL-1 receptor antagonist deficient (IL-1ra−/−) mice induce inflammation in joints like RA. In RA therapy, although AMSC improves the inflammation activity, it is little known to play roles of extracellular microvesicles (EV) for improvement of RA. To clarify the MSC-derived EVs are involved amelioration mechanisms for RA by themselves, we examined the functional effects of development for RA by AMSC-EVs.MethodsWe isolated AMSCs derived mice adipose tissue and purified EVs from the culture supernatant of AMSCs. To examine whether EVs can improve RA, we administrated EVs or AMSCs to IL-1ra knockout mice as RA model mice. We analyzed EVs-included factor by western blot methods and RA improvement effect by ELISA.ResultsIn this study, we showed that the swellings of joints on mice in wild type AMSC and that in AMSC-EVs decreased than that in IL-1ra−/− mice-AMSC-EVs and in none-treated. We detected IL-1ra expression in AMSC-EVs in wild type mice but not that in IL-1ra−/− mice. Proinflammatory cytokine expression changes in mice showed in AMSCs and AMSC-EVs, but no apparent differences cytokine expressions were detected in IL-1ra−/− mice.ConclusionsIn this study, we concluded that MSCs might improve RA by the transferring of factors such as IL-1ra, which are included their MSC derived- EVs.

Mesenchymal stem cells ameliorate experimental arthritis via expression of interleukin-1 receptor antagonist.

Human bone marrow-derived mesenchymal stem cells (MSCs) have been observed to inhibit arthritis in experimental animal models such as collagen-induced arthritis. However, the exact anti-inflammatory mechanisms remain poorly understood. Interleukin-1 receptor antagonist (IL-1Ra) is an anti-inflammatory cytokine produced by immune and stromal cells. We postulated that MSCs could produce IL-1Ra and attenuate experimental arthritis. In this study, 5x106 MSCs were injected into the peritoneal cavity of IL-1Ra knockout (IL-1RaKO) mice. MSCs reduced the severity of the arthritis by histology and decreased pro-inflammatory cytokine levels in IL-1RaKO mice. The ratio of splenic T helper 17 (Th17) cells to regulatory T cells (Treg) was significantly decreased in MSC-injected IL-1RaKO mice. Purified splenic CD4+ T cells from mice in each of the treatment groups were cultured under Th17 polarizing conditions and analyzed by flow cytometry. Less expansion of the Th17 population was observed in the MSC-treated group. Interestingly, MSCs expressed inducible IL-1Ra against inflammatory environmental stimuli. Human recombinant IL-1Ra could suppress Th17 cells differentiation under Th17 polarizing conditions. These results indicate that IL-1Ra expressed by MSCs can inhibit Th17 polarization and decrease the immune response in IL-1RaKO mice. Therefore, MSC-derived IL-1Ra may inhibit inflammation in IL-1RaKO mice via effects on Th17 differentiation.

Neuropathological and behavioral sequelae in IL-1R1 and IL-1Ra gene knockout mice after soman (GD) exposure

Soman (GD) exposure results in status epilepticus (SE) that leads to neurodegeneration, neuroinflammation, and behavioral consequences including learning and memory deficits. The neuroinflammatory response is characterized by the upregulation of the pro-inflammatory cytokine, interleukin-1 (IL-1), which mediates the expression of other neurotoxic cytokines induced after GD exposure. However, the specific role of IL-1 signaling has not been defined in terms of the consequences of GD-induced SE. Therefore, the purpose of this study was to regulate IL-1 signaling and study the behavioral deficits and neurodegeneration that occur after convulsion onset. Wild type (WT), IL-1 receptor (IL-1R1) knockout (KO), and IL-1 receptor antagonist (IL-1Ra) KO mice were exposed to a convulsive dose of GD, and behavior was evaluated up to 18days later. Activity was studied using the Open Field, anxiety was assessed in the Zero Maze, and spatial learning and memory were evaluated with the Barnes Maze. The animals were euthanized at 24hours and 18days to determine neuropathology in the piriform cortex, amygdala, thalamus, and CA1, CA2/3, and CA4 regions of the hippocampus. Unlike the IL-1Ra KO, the IL-1R1 KO showed less neuropathology compared to WT at 24hours, but moderate to severe injury was found in all strains at 18days. Compared to their saline controls, the exposed WT mice were significantly more active in the Open Field, and the IL-1R1 KO strain showed reduced anxiety in the Zero Maze Test. Compared to WT mice, IL-1R1 and IL-1Ra KO mice had spatial learning and memory impairments in the Barnes Maze. Therefore, the IL-1 signaling pathway affects neurodegeneration and behavior after GD-induced convulsions.

Clofazimine Biocrystal Accumulation in Macrophages Upregulates Interleukin 1 Receptor Antagonist Production To Induce a Systemic Anti-Inflammatory State.

Clofazimine (CFZ) is a poorly soluble antibiotic and anti-inflammatory drug indicated for the treatment of leprosy. In spite of its therapeutic value, CFZ therapy is accompanied by the formation of drug biocrystals that accumulate within resident tissue macrophages, without obvious toxicological manifestations. Therefore, to specifically elucidate the off-target consequences of drug bioaccumulation in macrophages, we compared the level of inflammasome activation in CFZ-accumulating organs (spleen, liver and lung) in mice after 2 and 8 weeks of CFZ treatment when the drug exists in soluble and insoluble (biocrystalline) forms, respectively. Surprisingly, the results showed a drastic reduction in caspase 1 and interleukin-1β (IL-1β) cleavage in the livers of mice treated with CFZ for 8 weeks (8-week-CFZ-treated mice) compared to 2-week-CFZ-treated and control mice, which was accompanied by a 3-fold increase in hepatic IL-1 receptor antagonist (IL-1RA) production and a 21-fold increase in serum IL-1RA levels. In the lung and spleen, IL-1β cleavage and tumor necrosis factor alpha expression were unaffected by soluble or biocrystal CFZ forms. Functionally, there was a drastic reduction of carrageenan- and lipopolysaccharide-induced inflammation in the footpads and lungs, respectively, of 8-week-CFZ-treated mice. This immunomodulatory activity of CFZ biocrystal accumulation was attributable to the upregulation of IL-1RA, since CFZ accumulation had minimal effect in IL-1RA knockout mice or 2-week-CFZ-treated mice. In conclusion, CFZ accumulation and biocrystal formation in resident tissue macrophages profoundly altered the host's immune system and prompted an IL-1RA-dependent, systemic anti-inflammatory response.

Interleukin-1 receptor antagonist knockout mice as a model of the inflammatory bowel disease

Interleukin-1 receptor antagonist knockout mice as a model of the inflammatory bowel disease

Altered composition of gut microbiota in rheumatoid arthritis patients.

Manifestation of rheumatoid arthritis (RA) can be attributed to both genetic and environmental factors. Some researchers have been focusing on intestinal microbiota which is thought to be one of the environmental factors that may enhance the development of RA. The advancement of culture-independent, high throughput microbial DNA sequencing had enabled us to understand the interplay between intestinal microbiota and host immune systems. In this study, we have reviewed the previous findings in animal and human studies with respect to the role of intestinal microbiota in RA. Mouse models of arthritis have demonstrated that gut microbiota plays a critical role in the disease development. K/BxN and IL-1 receptor-antagonist knock-out mice did not develop disease in germ free condition, however, colonization of particular intestinal bacteria was sufficient to induce arthritis. Moreover, the dysbiosis was observed in the human RA patients from United States, China and Finland. Thus, we believe that endeavors to improve the dysbiosis would serve as a novel therapeutic or preventive strategy in RA patients.

Mesenchymal Stem Cell-Derived Interleukin 1 Receptor Antagonist Promotes Macrophage Polarization and Inhibits B Cell Differentiation.

The role of interleukin 1 receptor antagonist (IL1RA) in mediating the immunosuppressive effect of mesenchymal stem/stromal cells (MSCs) has been reported in several studies. However, how MSC-derived IL1RA influences the host response has not been clearly investigated. We therefore derived MSCs from the bone marrow of IL1RA knockout mice and evaluated their immunosuppressive effect on different immune cell subsets. IL1RA deficient (IL1RA(-/-) ) or wild type (wt) MSCs inhibited to the same extend the proliferation of T lymphocytes. On the contrary, IL1RA(-/-) MSCs were less effective than wt MSCs to induce in vitro the macrophage polarization from M1 to M2 phenotype secreting IL10 and exerting a suppressive effect on CD4(+) T cells. Moreover compared with wt MSCs, IL1RA(-/-) MSCs did not efficiently support the survival of quiescent B lymphocytes and block their differentiation toward CD19(+) CD138(+) plasmablasts secreting IgG antibodies. The effectiveness of IL1RA secreted by MSCs in controlling inflammation was further shown in vivo using the collagen-induced arthritis murine model. MSCs lacking IL1RA expression were unable to protect mice from arthritic progression and even worsened clinical signs, as shown by higher arthritic score and incidence than control arthritic mice. IL1RA(-/-) MSCs were not able to decrease the percentage of Th17 lymphocytes and increase the percentage of Treg cells as well as decreasing the differentiation of B cells toward plasmablasts. Altogether, our results provide evidence of the key role of IL1RA secreted by MSCs to both control the polarization of macrophages toward a M2 phenotype and inhibit B cell differentiation in vivo.

Development of synthetic anti-cyclic citrullinated peptide antibody and its arthritogenic role.

This study was undertaken to develop a novel anti-citrullinated peptide antibody (ACPA) and to investigate its arthritogenicity in a collagen-induced arthritis (CIA) model. The novel ACPA, 12G1, was developed by injecting cyclic citrullinated antigen in mice and subsequently hybridizing the B cells producing citrullinated peptide-specific antibodies with a myeloma cell line. The arthritic joints of mice with CIA and collagen antibody-induced arthritis (CAIA) as well as interleukin-1 receptor antagonist (IL-1Ra) knockout (KO) mice were stained immunohistochemically using the 12G1 antibody. Confocal immunostaining was used to identify colocalization of 12G1 with various citrullinated proteins. 12G1 in the presence or absence of chelating beads was administered to CIA mice on days 21 and 28 after type II collagen (CII) immunization to investigate 12G1 arthritogenecity. 12G1 detected citrullinated proteins in the arthritic joints of all the experimental arthritis models used. Confocal immunostaining showed that 12G1 was colocalized with well-known citrullinated proteins, including vimentin, collagen, anti-immunoglobulin binding protein and fibronectin. Staining of citrullinated proteins using 12G1 was more diffuse in CIA mice compared with CAIA and IL-1Ra KO mice. 12G1 injection apparently acted as a booster of immunization in CIA mice in combination with a single CII immunization, with this effect being abolished when 12G1 was injected with chelating beads. The novel ACPA, 12G1, identified various citrullinated proteins in the arthritic joints of three experimental arthritis models. 12G1-treated mice developed arthritis following a single CII immunization, suggesting an arthritogenic potential for ACPA in CIA mice.

Interleukin-1 Receptor Antagonist Has a Novel Function in the Regulation of Matrix Metalloproteinase-13 Expression.

Interleukin-1 receptor antagonist (IL-1Ra) is an IL-1 family member, which binds to IL-1 receptors but does not induce any intracellular signaling. We addressed whether IL-1Ra has a novel function in regulation of the extracellular matrix or adhesion molecules. Polymerase chain reaction array analysis demonstrated a ~5-fold increase in matrix metalloproteinase 13 (MMP-13) mRNA expression of IL-1Ra siRNA-transfected Ca9-22 human oral squamous epithelial carcinoma cells compared with the control. In fact, MMP-13 mRNA and protein expression as well as its activity in IL-1Ra siRNA-transfected Ca9-22 cell lines were significantly higher than those in the control. IL-1Ra siRNA treatment resulted in strong elevation of MMP-13 expression, whereas addition of rhIL-1Ra (40 ng/ml) suppressed MMP-13 expression, suggesting that IL-1Ra had a specific effect on MMP-13 induction. IL-1Ra siRNA could potently suppress IL-1α. No significant difference was found between the MMP-13 mRNA expression of IL-1Ra siRNA-transfected cells and those treated with anti-IL-1α or anti-IL-1β antibodies. These results suggested that continuous supply of IL-1 had no effect on the induction of MMP-13 by IL-1Ra siRNA. Histopathological investigation of MMP-13 in periodontal tissue showed specific localization in the junctional epithelial cells of IL-1Ra knockout (KO) mice. Furthermore, infection with Aggregatibacter actinomycetemcomitans to establish an experimental periodontitis model resulted in predominant localization of MMP-13 along apical junctional epithelial cells. Laminin-5, which is degraded by MMP-13, was found in the internal basal lamina of wild-type mice, whereas the internal basal lamina of IL-1Ra KO mice did not show obvious laminin-5 localization. In particular, laminin-5 localization almost disappeared in the internal basal lamina of IL-1Ra KO mice infected with A. actinomycetemcomitans, suggesting that the suppression of IL-1Ra resulted in strong induction of MMP-13 that degraded laminin-5. In conclusion, IL-1Ra is associated with MMP-13 expression and has a novel function in such regulation without interference of the IL-1 signaling cascade.

IL-1 receptor-antagonist (IL-1Ra) knockout mice show anxiety-like behavior by aging

Interleukin 1 (IL-1) plays a critical role in stress responses, and its mRNA is induced in the brain by restraint stress. Previously, we reported that IL-1 receptor antagonist (IL-1Ra) knockout (KO) mice, which lacked IL-1Ra molecules that antagonize the IL-1 receptor, showed anti-depression-like behavior via adrenergic modulation at the age of 8 weeks. Here, we report that IL-1Ra KO mice display an anxiety-like phenotype that is induced spontaneously by aging in the elevated plus-maze (EPM) test. This anxiety-like phenotype was improved by the administration of diazepam. The expression of the anxiety-related molecule glucocorticoid receptor (GR) was significantly reduced in 20-week-old but not in 11-week-old IL-1Ra KO mice compared to wild-type (WT) littermates. The expression of the mineralocorticoid receptor (MR) was not altered between IL-1Ra KO mice and WT littermates at either 11 or 20 weeks old. Analysis of monoamine concentration in the hippocampus revealed that tryptophan, the serotonin metabolite 5-hydroxyindole acetic acid (5-HIAA), and the dopamine metabolite homovanillic acid (HVA) were significantly increased in 20-week-old IL-1Ra KO mice compared to littermate WT mice. These findings strongly suggest that the anxiety-like behavior observed in older mice was caused by the complicated alteration of monoamine metabolism and/or GR expression in the hippocampus.

IL-12p40 homodimer (p40)2 ameliorates experimental autoimmune arthritis (THER3P.975)

Abstract Interleukin (IL)-23 is the key cytokine that induces the expansion of helper T (Th) 17 cells. It is composed of p19 and p40 subunits of IL-12. The p40 subunit binds competitively to the receptor of IL-23 and blocks its activity. Our aim was to assess the preventive and therapeutic effect of the (p40)2 subunit in autoimmune arthritis animal models. In the present study, by using IL-1receptor antagonist knockout mice (IL-1RaKO) and a collagen-induced arthritis (CIA) model, we inspected the suppressive effect of the IL-12p40 homodimer ((p40)2) on inflammatory arthritis. We demonstrated that the recombinant adenovirus expressing mouse (p40)2 (rAd/(p40)2) model prevented the development of arthritis when given before the onset of arthritis. It also decreased the arthritis index and joint erosions after it was transferred once arthritis was established in the mouse model. (p40)2 inhibited the production of inflammatory cytokines and antigen-specific T cell proliferation. It also induced the CD4+CD25+Foxp3 regulatory T (Treg) cells in vitro and in vivo, whereas the generation of RORgt and Th17 cells was suppressed. The induction process of Treg cells and the suppression of Th17 cells were mediated via the activated STAT5 and suppressed STAT3. Conclusion: Our data suggested that (p40)2 suppressed inflammatory arthritis successfully. This could be a useful therapeutic approach in autoimmune arthritis to regulate the Th17/Treg balance and IL-23 signaling.

Inflammatory Bone Loss in Experimental Periodontitis Induced by Aggregatibacter actinomycetemcomitans in Interleukin-1 Receptor Antagonist Knockout Mice

The interleukin-1 receptor antagonist (IL-1Ra) binds to IL-1 receptors and inhibits IL-1 activity. However, it is not clear whether IL-1Ra plays a protective role in periodontal disease. This study was undertaken to compare experimental periodontitis induced by Aggregatibacter actinomycetemcomitans in IL-1Ra knockout (KO) mice and wild-type (WT) mice. Computed tomography (CT) analysis and hematoxylin-and-eosin (H&E) and tartrate-resistant acid phosphatase (TRAP) staining were performed. In addition, osteoblasts were isolated; the mRNA expression of relevant genes was assessed by real-time quantitative PCR (qPCR); and calcification was detected by Alizarin Red staining. Infected IL-1Ra KO mice exhibited elevated (P, <0.05) levels of antibody against A. actinomycetemcomitans, bone loss in furcation areas, and alveolar fenestrations. Moreover, protein for tumor necrosis factor alpha (TNF-α) and IL-6, mRNA for macrophage colony-stimulating factor (M-CSF), and receptor activator of NF-κB ligand (RANKL) in IL-1Ra KO mouse osteoblasts stimulated with A. actinomycetemcomitans were increased (P, <0.05) compared to in WT mice. Alkaline phosphatase (ALP), bone sialoprotein (BSP), osteocalcin (OCN)/bone gla protein (BGP), and runt-related gene 2 (Runx2) mRNA levels were decreased (P, <0.05). IL-1α mRNA expression was increased, and calcification was not observed, in IL-1 Ra KO mouse osteoblasts. In brief, IL-1Ra deficiency promoted the expression of inflammatory cytokines beyond IL-1 and altered the expression of genes involved in bone resorption in A. actinomycetemcomitans-infected osteoblasts. Alterations consistent with rapid bone loss in infected IL-Ra KO mice were also observed for genes expressed in bone formation and calcification. In short, these data suggest that IL-1Ra may serve as a potential therapeutic drug for periodontal disease.

EGCG Attenuates Autoimmune Arthritis by Inhibition of STAT3 and HIF-1α with Th17/Treg Control

Epigallocatechin-3-gallate (EGCG) is a green tea polyphenol exerting potent anti-oxidant and anti-inflammatory effects by inhibiting signaling and gene expression. The objective of the study was to evaluate the effect of EGCG on interleukin (IL)-1 receptor antagonist knockout (IL-1RaKO) autoimmune arthritis models. IL-1RaKO arthritis models were injected intraperitoneally with EGCG three times per week after the first immunization. EGCG decreased the arthritis index and showed protective effects against joint destruction in the IL-1RaKO arthritis models. The expression of pro-inflammatory cytokines, oxidative stress proteins, and p-STAT3 (Y705) and p-STAT3 (S727), mTOR and HIF-1α were significantly lower in mice treated with EGCG. EGCG reduced osteoclast markers in vivo and in vitro along with anti-osteoclastic activity was observed in EGCG-treated IL-1RaKO mice. The proportion of Foxp3+ Treg cells increased in the spleens of mice treated with EGCG, whereas the proportion of Th17 cells reduced. In vitro, p-STAT3 (Y705) and p-STAT3 (S727), HIF1α and glycolytic pathway molecules were decreased by EGCG. EGCG suppressed the activation of mTOR and subsequently HIF-1α, which is considered as a metabolic check point of Th17/Treg differentiation supporting the therapeutic potential of EGCG in autoimmune arthritis.

TWEAK Promotes Osteoclastogenesis in Rheumatoid Arthritis

Bone destruction is critical in the functional disability of patients with rheumatoid arthritis (RA). Osteoclasts, specialized bone-resorbing cells regulated by cytokines, such as receptor activator of NF-κB ligand (RANKL), are primarily implicated in bone destruction in RA. The aim of the study was to examine whether tumor necrosis factor-like weak inducer of apoptosis (TWEAK), a member of the tumor necrosis factor superfamily, has osteoclastogenic activity in patients with RA and in animal models, including mice with collagen-induced arthritis (CIA) and IL-1 receptor antagonist knockout (IL-1RaKO) mice. TWEAK was increased in the synovium, synovial fluid, and serum of patients with RA and in the synovium of CIA mice and IL-1RaKO mice. TWEAK induced RANKL expression in mixed joint cells and splenocytes from CIA mice, IL-1RaKO mice, and fibroblast-like synoviocytes from patients with RA. Both osteoclast precursor cells and osteoclasts express TWEAK receptor fibroblast growth factor-inducible 14. In addition, TWEAK enhanced invitro osteoclastogenesis without the presence of RANKL-providing cells and by inducing RANKL expression in fibroblast-like synoviocytes. Moreover, treatment with fibroblast growth factor-inducible 14-Fc inhibited RANKL-induced osteoclastogenesis, indicating that endogenous TWEAK also has osteoclastogenic activity. Our data demonstrated that TWEAK promotes osteoclastogenesis in RA, suggesting that therapeutic strategies targeting TWEAK could be effective for treatment of patients with RA, especially in preventing bone destruction.

SAT0079 The analysis of fecal microbiota in rheumatoid arthritis patients compared to healthy volunteers using bacterial RRNA-targeted reverse transcription-quantitative PCR

BackgroundGut microbiota have long been thought to contribute to inflammatory disease, and some have considered the bacterial flora as one of the environmental factors causing rhumatoid arthritis (RA). Recently, two...

Lipopolysaccharide of Aggregatibacter actinomycetemcomitans up‐regulates inflammatory cytokines, prostaglandin E2 synthesis and osteoclast formation in interleukin‐1 receptor antagonist‐deficient mice

The interleukin (IL)-1 receptor antagonist (Ra) binds to IL-1 receptors and inhibits IL-1 activity. However, it is unclear whether the IL-1Ra plays a protective role in periodontal disease. The purpose of this study was to compare IL-1Ra knockout (KO) and wild-type (WT) mice in regard to proinflammatory cytokine production, osteoclast formation and bone resorption in response to periodontal bacterial lipopolysaccharide (LPS). Peritoneal macrophages (Mφs) were obtained from 13-wk-old IL-1Ra KO and WT mice. Peritoneal Mφs were cultured with or without 10μg/mL of Aggregatibacter actinomycetemcomitans LPS for 24h. The levels of IL-1alpha (IL-1α), IL-1beta (IL-1β), tumor necrosis factor-α (TNF-α) and IL-6 were measured in periotoneal Mφs supernatant fluid (PM-SF) using an ELISA. Bone marrow cells were obtained from the mice and stimulated with PM-SF for 9d, then stained with TRAP. The frequency of TRAP-positive multinucleated giant cell formation was calculated based on a fusion index. PM-SF-stimulated calvarial bone resorption was analyzed using micro-computed tomography, and calvarial histological analysis was performed using hematoxylin and eosin and TRAP staining. The expression of cyclooxygenase-2 (Cox2), prostanoid receptor EP4 (Ep4) and Rank mRNAs in bone marrow cells were measured using real-time quantitative PCR, while prostaglandin E2 (PGE2 ) production was determined by ELISA. The levels of IL-1α, IL-1β, TNF-α and IL-6 in IL-1Ra KO mice PM-SF stimulated with A.actinomycetemcomitans LPS were significantly increased by approximately 4- (p<0.05), 5- (p<0.05), 1.3- (p<0.05) and 6- (p<0.05) fold, respectively, compared with the levels in WT mice. Moreover, osteoclast formation, expression of Rank, Ep4 and Cox2 mRNAs and production of PGE2 were significantly increased by approximately 2- (p<0.05), 1.6- (p<0.05), 2.5- (p<0.05), 1.6- (p<0.05) and 1.9- (p<0.05) fold, respectively, in IL-1Ra KO mice stimulated with A.actinomycetemcomitans LPS compared with WT mice. IL-1Ra regulates IL-1 activity and appears to reduce the levels of other inflammatory cytokines, including TNF-α and IL-6, while it also reduces expression of the EP4 receptor related to prostanoid sensitivity and osteoclast formation. These results suggest that IL-1Ra is an important molecule for inhibition of inflammatory periodontal bone resorption.

Lack of TLR4 on bone marrow derived cells ameliorates experimental arthritis and decreases cd4- IL-17+ cells

Background and objectivesThe IL-1 receptor antagonist knockout mice (IL-1Ra-/-) spontaneously develop a T cell driven arthritis with profound IL-17 production. When cross bred with TLR4 knock out (TLR4-/-) these animals...

Impact of IL-1 signalling on experimental uveitis and arthritis

BackgroundUveitis, or inflammatory eye disease, is a common extra-articular manifestation of many systemic autoinflammatory diseases involving the joints. Anakinra (recombinant interleukin (IL)-1 receptor antagonist (Ra)) is an effective therapy in...

Interleukin-1 Receptor Antagonist Modulates the Early Phase of Liver Regeneration after Partial Hepatectomy in Mice

BackgroundCytokine administration is a potential therapy for acute liver failure by reducing inflammatory responses and favour hepatocyte regeneration. The aim of this study was to evaluate the role of interleukin-1 receptor antagonist (IL-1ra) during liver regeneration and to study the effect of a recombinant human IL-1ra on liver regeneration.MethodsWe performed 70%-hepatectomy in wild type (WT) mice, IL-1ra knock-out (KO) mice and in WT mice treated by anakinra. We analyzed liver regeneration at regular intervals by measuring the blood levels of cytokines, the hepatocyte proliferation by bromodeoxyuridin (BrdU) incorporation, proliferating cell nuclear antigen (PCNA) and Cyclin D1 expression. The effect of anakinra on hepatocyte proliferation was also tested in vitro using human hepatocytes.ResultsAt 24h and at 48h after hepatectomy, IL-1ra KO mice had significantly higher levels of pro-inflammatory cytokines (IL-6, IL-1β and MCP-1) and a reduced and delayed hepatocyte proliferation measured by BrdU incorporation, PCNA and Cyclin D1 protein levels, when compared to WT mice. IGFBP-1 and C/EBPβ expression was significantly decreased in IL-1ra KO compared to WT mice. WT mice treated with anakinra showed significantly decreased levels of IL-6 and significantly higher hepatocyte proliferation at 24h compared to untreated WT mice. In vitro, primary human hepatocytes treated with anakinra showed significantly higher proliferation at 24h compared to hepatocytes without treatment.ConclusionIL1ra modulates the early phase of liver regeneration by decreasing the inflammatory stress and accelerating the entry of hepatocytes in proliferation. IL1ra might be a therapeutic target to improve hepatocyte proliferation.