Roles of IL-1 in the development of rheumatoid arthritis: consideration from mouse models

Regulatory Role of IL6 in Immune-Related Adverse Events during Checkpoint Inhibitor Treatment in Melanoma

The landscape of clinical management for metastatic melanoma (MM) and other solid tumors has been modernized by the advent of immune checkpoint inhibitors (ICI), including programmed cell death-1 (PD-1), programmed cell death-ligand 1 (PD-L1), and cytotoxic T lymphocyte antigen 4 (CTLA-4) inhibitors. While these agents demonstrate efficacy in suppressing tumor growth, they also lead to immune-related adverse events (irAEs), resulting in the exacerbation of autoimmune diseases such as rheumatoid arthritis (RA), ulcerative colitis (UC), and Crohn's disease (CD). The immune checkpoint inhibitors offer promising advancements in the treatment of melanoma and other cancers, but they also present significant challenges related to irAEs and autoimmune diseases. Ongoing research is crucial to better understand these challenges and develop strategies for mitigating adverse effects while maximizing therapeutic benefits. In this manuscript, we addressed this challenge using network-based approaches by constructing and analyzing the molecular and signaling networks associated with tumor-immune crosstalk. Our analysis revealed that IL6 is the key regulator responsible for irAEs during ICI therapies. Furthermore, we conducted an integrative network and molecular-level analysis, including virtual screening, of drug libraries, such as the Collection of Open Natural Products (COCONUT) and the Zinc15 FDA-approved library, to identify potential IL6 inhibitors. Subsequently, the compound amprenavir was identified as the best molecule that may disrupt essential interactions between IL6 and IL6R, which are responsible for initiating the signaling cascades underlying irAEs in ICI therapies.

Novel mannich-based derivative of 2-mercaptobenzimidazole (AK7): a new candidate for the treatment of inflammatory arthritis owing to its NF-κB1 inhibitory potential

This study investigated the anti-arthritic potential of novel mannich-based derivatives of 2-mercaptobenzimidazole (AK7 and AK9) in rats. The compounds were characterized by NMR and FTIR spectroscopies and their acute anti-inflammatory effects were measured by carrageenan (CRG)-induced paw edema model. The most potent doses of AK7 and AK9 were subsequently evaluated in the complete Freund's adjuvant (CFA)-induced inflammatory arthritis model. AK7 and AK9 inhibited CRG-induced inflammation in a dose-dependent fashion and a similar reduction in CFA-induced paw inflammation was observed. Moreover, X-ray and histopathological analyses of AK7-treated animals displayed normal joint structure whereas AK9, despite of its anti-inflammatory effects, failed to protect against cartilage destruction. Interestingly, biochemical analysis revealed a better safety profile for AK7 than for AK9 and methotrexate. Both compounds suppressed mRNA levels of pro-inflammatory mediators (IRAK1, NF-κB1, TNF-α, IL1B) while only AK7 reduced the transcript levels of interstitial collagenase (MMP1). Molecular docking analysis of AK7 and AK9 with TNF-α and MMP1 also supported the experimental data. These findings clearly highlight the beneficial effects of AK7 in the prevention and/or treatment of inflammatory arthritis.

Dysfunction in parkin aggravates inflammatory bone erosion by reinforcing osteoclast activity

BACKGROUND

Parkin dysfunction associated with the progression of parkinsonism contributes to a progressive systemic skeletal disease characterized by low bone mineral density. However, the role of parkin in bone remodeling has not yet been elucidated in detail.

RESULT

We observed that decreased parkin in monocytes is linked to osteoclastic bone-resorbing activity. siRNA-mediated knockdown of parkin significantly enhanced the bone-resorbing activity of osteoclasts (OCs) on dentin without any changes in osteoblast differentiation. Moreover, Parkin-deficient mice exhibited an osteoporotic phenotype with a lower bone volume accompanied by increased OC-mediated bone-resorbing capacity displaying increased acetylation of α-tubulin compared to wild-type (WT) mice. Notably, compared to WT mice, the Parkin-deficient mice displayed increased susceptibility to inflammatory arthritis, reflected by a higher arthritis score and a marked bone loss after arthritis induction using K/BxN serum transfer, but not ovariectomy-induced bone loss. Intriguingly, parkin colocalized with microtubules and parkin-depleted-osteoclast precursor cells (Parkin^-/- OCPs) displayed augmented ERK-dependent acetylation of α-tubulin due to failure of interaction with histone deacetylase 6 (HDAC6), which was promoted by IL-1β signaling. The ectopic expression of parkin in Parkin^-/- OCPs limited the increase in dentin resorption induced by IL-1β, accompanied by the reduced acetylation of α-tubulin and diminished cathepsin K activity.

CONCLUSION

These results indicate that a deficiency in the function of parkin caused by a decrease in parkin expression in OCPs under the inflammatory condition may enhance inflammatory bone erosion by altering microtubule dynamics to maintain OC activity.

Study of exopolysaccharide produced by Streptomyces rochie strain OF1 and its effect as ameliorative on osteoarthritis in rats via inhibiting TNF-α/COX2 pathway

BACKGROUND

Carbohydrates are known as the main natural products of life activities.

RESULTS

Streptomyces rochie strain OF1 isolated from a mangrove tree produced exopolysaccharide S5 (EPSS5) (14.2 gl^-1) containing uronic acid 21.98% sulfate content of 11.65 mg/ml, and a viscosity of 1.35 mm²/s. while total hexose amine content was 24.72%. The high performance liquid chromatography (HPLC) analysis of mono sugars revealed that EPS was composed of manouronic acid, glucuronic acid, xylose, and fructose at a molar ratio of 1.0:0.5:1.0:2.0, respectively. It showed that the whole antioxidant activity was 92.06%. It showed antibacterial activity against Staphylococcus aureus, and E. coli, MRSA and Klebsiella pneumoniae. But, EPSS5 displayed low antifungal activity against Candida albicans. While no antifungal activity has been detected against Aspergillus niger. EPSS5 has antibiofilm action that is noticeable toward S. aureus with an inhibition ratio of biofilm up to 50%. Effect of EPS on serum levels of TNF-α and COX2 by 2 fold and 1.9 fold of EPS reduced serum levels of Tumor necrosis factor-α (TNF-α) by 38%, 12%, 49%, and Cyclooxygenase-2 (COX2) by 61%, 34%, and 62%, respectively. By affected of EPSS5 on arthritis in rats stimulated by carrageenan.

CONCLUSIONS

Administration of EPS ameliorated carrageen-induced elevation in inflammatory mediators; TNF-α/COX and suppressed the expressions of metalloproteinase 9 (MMP9) by 68%, 86%, and 75% correspondingly in comparison to the group of carrageenans. Then again, therapy involving a high dose only reduced MMP9 level by 57%, compared to free drug suggesting that EPSS5 is a good inhibitor of the MMP9, as it brought MMP9 back to normal levels via the signaling pathway.

Bench to Bedside: Modelling Inflammatory Arthritis

Inflammatory arthritides such as rheumatoid arthritis are a major cause of disability. Pre-clinical murine models of inflammatory arthritis continue to be invaluable tools with which to identify and validate therapeutic targets and compounds. The models used are well-characterised and, whilst none truly recapitulates the human disease, they are crucial to researchers seeking to identify novel therapeutic targets and to test efficacy during preclinical trials of novel drug candidates. The arthritis parameters recorded during clinical trials and routine clinical patient care have been carefully standardised, allowing comparison between centres, trials, and treatments. Similar standardisation of scoring across in vivo models has not occurred, which makes interpretation of published results, and comparison between arthritis models, challenging. Here, we include a detailed and readily implementable arthritis scoring system, that increases the breadth of arthritis characteristics captured during experimental arthritis and supports responsive and adaptive monitoring of disease progression in murine models of inflammatory arthritis. In addition, we reference the wider ethical and experimental factors researchers should consider during the experimental design phase, with emphasis on the continued importance of replacement, reduction, and refinement of animal usage in arthritis research.

Investigation of the effects of safranal on the experimentally created rheumatoid arthritis model in rats

Rheumatoid arthritis (RA) is a systemic chronic disease characterized by inflammation and synovitis. More effective treatment methods with less side effects need to be developed. In this context, current study investigated the therapeutic effects of safranal in a model of complete Freund's adjuvant (CFA)-induced RA. The control group was given 1 ml of saline orally starting from the 8th day, and 0.2 ml of CFA was given to the RA, RA + Safranal and RA + Methotrexate (MTX) groups on the 0th day of the experiment. Starting from the 8th day of the experiment, 1 ml of saline was given to the RA group, safranal was given at 200 mg/kg of body weight to the RA + MTX group, and 3 mg/kg of MTX to the RA + MTX group twice a week. The results showed that weight gain decreased in the RA group compared to the control group while arthritis index score, thymus index, and planter temperature were found to be increased. Additionally, a deterioration in blood parameters, an increase in alanine aminotransferase, aspartate aminotransferase, urea, creatinine, C-reactive protein, and malondialdehyde levels, and a decrease in reduced glutathione levels and glutathione peroxidase and catalase (CAT) activities were seen while tumor necrosis factor-α, interleukin-6 (IL-6), cyclooxygenase-2, nuclear factor kappa B levels were found to be increased. However, the safranal had a regulatory effect on all the values, except IL-6 and CAT, and blood parameters. Moreover, histopathological examination revealed that safranal reduced inflammatory cell infiltration and edema.

Transplantation of IL‑1β siRNA‑modified bone marrow mesenchymal stem cells ameliorates type II collagen‑induced rheumatoid arthritis in rats

Rheumatoid arthritis (RA) is a chronic autoimmune disease that causes erosion of articular cartilage and bone and has adverse effects on both patients and livestock animals. The aim of the present study was to investigate the role of interleukin-1β (IL-1β) in the pathogenesis of RA, and to further determine whether injection of IL-1β small interfering RNA (siRNA) or transplantation of IL-1β siRNA + bone marrow mesenchymal stem cells (BMSCs) can ameliorate RA in rats. A collagen-induced arthritis (CIA) rat model was established by injecting type II collagen for 4 weeks. Next, CIA rats were randomly divided into three groups and injected or transplanted with PBS, IL-1β siRNA and IL-1β siRNA + BMSCs for another 4 weeks. The CIA rat model was successfully established, as demonstrated by the higher toe swelling value, thymus and spleen/body weight, immobility time and serum IL-1β concentration, as well as lower body weight, climbing time and mRNA expression of programmed death-1 (PD-1), transforming growth factor-β1 (TGF-β1) and forkhead box protein 3 (Foxp3) in the spleen, compared with control rats. Furthermore, histopathology results demonstrated that joint swelling and redness were observed in the knee joints of CIA rats. H&E results revealed that CIA rats presented erosive destruction of the bone and ulceration of the articular cartilage. In addition, in vitro results demonstrated that IL-1β expression was successfully silenced after IL-1β siRNA transfection in lipopolysaccharide-stimulated BMSCs. When compared with the results of PBS rats, both IL-1β siRNA injection and IL-1β siRNA + BMSC transplantation significantly increased the body weight, climbing time and mRNA expression of PD-1, TGF-β1 and Foxp3 in the spleen, while significantly reduced the immobility time and serum IL-1β concentration. In addition, when compared with that of IL-1β siRNA injection, IL-1β siRNA + BMSC transplantation exhibited markedly higher therapeutic efficacy against CIA. These results demonstrated that higher IL-1β contributed to the pathogenesis of CIA, and that IL-1β siRNA injection ameliorated CIA, while its combination with BMSCs exerted synergistic effects, which may be beneficial against RA.

Preclinical evaluation of methotrexate-loaded polyelectrolyte complexes and thermosensitive hydrogels as treatment for rheumatoid arthritis

This work proposes new methotrexate (MTX) loaded drug delivery systems (DDS) to treat rheumatoid arthritis via the intra-articular route: a poloxamer based thermosensitive hydrogel (MTX-HG), oligochitosan and hypromellose phthalate-based polyelectrolyte complexes (MTX-PEC) and their association (MTX-PEC-HG). MTX-PEC showed 470 ± 166 nm particle size, 0.298 ± 0.108 polydispersity index, +26 ± 2 mV and 74.3 ± 5.8% MTX efficiency entrapment and particle formation was confirmed by infrared spectroscopy and thermal analysis. MTX-HG and MTX-PEC-HG gelled at 36.7°C. MTX drug release profile was prolonged for MTX-HG and MTX-PEC-HG, and faster for MTX-PEC and free MTX. The in vivo effect of the MTX-DDSs systems was evaluated in induced arthritis rats as single intra-articular dose. The assessed parameters were the mechanical nociceptive threshold, the plasmatic IL-1β level and histological analysis of the tibiofemoral joint. MTX-HG and MTX-PEC-HG performance were similar to free MTX and worse than oral MTX, used as positive control. All DDSs showed some irritative effect, for which further studies are required. MTX-PEC was the best treatment on recovering cartilage damage and decreasing allodynia. Thus, MTX-PEC demonstrated potential to treat rheumatoid arthritis, with the possibility of decreasing the systemic exposure to the drug.

The Therapeutic Landscape of Rheumatoid Arthritis: Current State and Future Directions

Rheumatoid arthritis (RA) is a debilitating autoimmune disease with grave physical, emotional and socioeconomic consequences. Despite advances in targeted biologic and pharmacologic interventions that have recently come to market, many patients with RA continue to have inadequate response to therapies, or intolerable side effects, with resultant progression of their disease. In this review, we detail multiple biomolecular pathways involved in RA disease pathogenesis to elucidate and highlight pathways that have been therapeutic targets in managing this systemic autoimmune disease. Here we present an up-to-date accounting of both emerging and approved pharmacological treatments for RA, detailing their discovery, mechanisms of action, efficacy, and limitations. Finally, we turn to the emerging fields of bioengineering and cell therapy to illuminate possible future targeted therapeutic options that combine material and biological sciences for localized therapeutic action with the potential to greatly reduce side effects seen in systemically applied treatment modalities.

Synoviolin is not a pathogenic factor for auto-inflammatory diseases

Auto-inflammatory syndromes are rare diseases characterized by arthritis and joint destruction, symptoms similar to but distinct from rheumatoid arthritis (RA). Therapeutic targets have not been well characterized for auto-inflammatory syndromes, although the E3 ligase Synoviolin was previously shown to be a novel therapeutic target for RA. Here, we show that Synoviolin loss has little impact on a model of auto-inflammatory diseases. We previously established such a model, the hIL-1 cTg mouse, in which IL-1 signaling was constitutively activated, and animals exhibit symptoms recapitulating auto-inflammatory syndromes such as major joint dominant arthritis. Here, we crossed hIL-1 cTg with Synoviolin flox'd mice to yield hIL-1 cTg/Synoviolin cKO mice. Synoviolin gene expression was ablated in adult hIL-1 cTg/Synoviolin cKO mice by injection of pIpC to activate Mx1 promoter-driven Cre recombinase. However, symptoms seen in hIL-1 cTg mice such as arthritis and joint destruction were not alleviated by targeting Synoviolin, ruling out Synoviolin as a therapeutic target for auto-inflammatory disease. Our results indicate that although similar, RA and auto-inflammatory diseases are different diseases, and treatment strategies should differ accordingly.

Non-Transcriptional and Translational Function of Canonical NF-κB Signaling in Activating ERK1/2 in IL-1β-Induced COX-2 Expression in Synovial Fibroblasts

The pro-inflammatory cytokine interleukin 1β (IL-1β) induces the synthesis of prostaglandin E₂ by upregulating cyclooxygenase-2 (COX-2) in the synovial tissue of individuals with autoimmune diseases, such as rheumatoid arthritis (RA). IL-1β-mediated stimulation of NF-κB and MAPK signaling is important for the pathogenesis of RA; however, crosstalk(s) between NF-κB and MAPK signaling remains to be understood. In this study, we established a model for IL-1β-induced synovitis and investigated the role of NF-κB and MAPK signaling in synovitis. We observed an increase in the mRNA and protein levels of COX-2 and prostaglandin E₂ release in cells treated with IL-1β. NF-κB and ERK1/2 inhibitors significantly reduced IL-1β-induced COX-2 expression. IL-1β induced the phosphorylation of canonical NF-κB complex (p65 and p105) and degradation of IκBα. IL-1β also induced ERK1/2 phosphorylation but did not affect the phosphorylation levels of p38 MAPK and JNK. IL-1β failed to induce COX-2 expression in cells transfected with siRNA for p65, p105, ERK1, or ERK2. Notably, NF-κB inhibitors reduced IL-1β-induced ERK1/2 phosphorylation; however, the ERK1/2 inhibitor had no effect on the phosphorylation of the canonical NF-κB complex. Although transcription and translation inhibitors had no effect on IL-1β-induced ERK1/2 phosphorylation, the silencing of canonical NF-κB complex in siRNA-transfected fibroblasts prevented IL-1β-induced phosphorylation of ERK1/2. Taken together, our data indicate the importance of the non-transcriptional/translational activity of canonical NF-κB in the activation of ERK1/2 signaling involved in the IL-1β-induced development of autoimmune diseases affecting the synovial tissue, such as RA.

Systemic bee venom exerts anti-arthritic and anti-inflammatory properties in a rat model of arthritis

Bee venom (BV) is widely used as a traditional China medicine to treat various conditions, including rheumatoid arthritis (RA). The aim of the present study was to evaluate the effects of systemic BV (60 mg/kg) as an anti-arthritic natural product, compare it with Methotrexate and determine the possible underlying mechanisms of BV action using complete Freund's adjuvant-induced arthritic rats. The development of signs of RA signs (knee joint circumference and arthritis scoring index) was evaluated. Erythrocyte sedimentation rate, serum tumor necrosis factor-α (TNF-α) and serum interleukin-1β (IL-1β) levels were measured at the end of the study. Histopathological examination followed by immunostaining of NF-κB (P65) was performed on the affected knee joints. Additionally, in vitro cyclooxygenase (COX) inhibition activity, carrageenan paw edema test and acetic acid writhing tests were performed to evaluate the anti-inflammatory and analgesic effects of the assessed dose and compared with diclofenac. An acute toxicity test was performed to establish the safety of BV at high doses. The results of the present study highlighted the potential of systemic BV on preventing the development of signs of RA. BV also significantly reduced serum levels of TNF-α, IL-1β and NF-κB in the affected joints. In addition to its potent analgesic activity, BV exhibited favorable inhibitory activity of the COX pathway in both in vivo and in vitro models. Therefore, high dose administration of systemic BV displayed safe and promising anti-arthritic, anti-inflammatory and analgesic properties through regulation of different mechanisms associated with the pathogenesis of RA.

Benzylideneacetophenone Derivative Alleviates Arthritic Symptoms via Modulation of the MAPK Signaling Pathway

The benzylideneacetophenone derivative 3-(4-hydroxy-3-methoxy-phenyl)-1-{3-[1]-phenyl}-propenone (JC3 dimer) was synthesized through the dimerization of JC3. To investigate the inhibitory effects of JC3 dimer, the carrageenan/kaolin (C/K)-induced knee arthritis rat model was used in vivo and rheumatoid arthritis (RA) patient-derived fibroblast-like synoviocytes (FLS) were used in vitro. In the C/K rat model, JC3 dimer was given after arthritis induction for 6 days at the concentrations of 1, 5, or 10 mg/kg/day. Manifestation of arthritis was evaluated using knee thickness, weight distribution ratio (WDR), and squeaking test. The levels of prostaglandin E₂ (PGE₂), interleukin (IL)-6, and tumor necrosis factor (TNF)-α in the serum of JC3 dimer-treated arthritic rats were also analyzed. Histological examination of the knee joints was also done. For the FLS, the cells were stimulated using IL-1β and concentrations of 1, 5, and 10 μg/mL JC3 dimer were used. The levels of IL-8, IL-6, and PGE₂ were measured in stimulated FLS treated with JC3 dimer. At days 5 to 6 after arthritis induction, JC3 dimer treatment significantly decreased arthritic symptoms and reduced the inflammation in the knee joints in the histology of knee tissues in C/K-arthritic rats. In stimulated FLS, JC3 dimer suppressed the increase of IL-8, IL-6, and PGE₂. These findings suggest that JC3 dimer has suppressive effects on arthritis, and that JC3 dimer can be a potential agent for arthritis therapy.

Chronotherapy targeting cytokine secretion attenuates collagen-induced arthritis in mice

OBJECTIVE

Diurnal variation of symptoms are observed in rheumatoid arthritis, especially in productions of cytokines that show peak concentrations during mid night. In contrast, cytokines of collagen-induced arthritis (CIA) mice increase in daytimes under Mid-light condition. By using chronotherapy, differences in drug efficacies according to administration time of Baricitinib, a wide ranged cytokine blocker, were examined in CIA mice.

METHODS

CIA mice were administered a dose of 3 mg/kg of Baricitinib once a day at zeitgeber time (ZT) 0 or ZT12 for 21 days. Arthritis scores, histopathology and factors related to joint destruction in sera were examined. Phosphorylation of STAT3 in liver, expressions of cytokines in spleen, and Interleukin (IL)-6 and tumor necrosis factor (TNF)-α in sera were measured.

RESULTS

In CIA mice, diurnal variations were observed both in expressions of cytokines and phosphorylation of STAT3. Arthritis scores of ZT0/12 group decreased from day3 as compared to untreated mice, and those of ZT0 group significantly decreased as compared to ZT12 group from day12. Pathological findings, immunohistochemistry of cytokines and Receptor activator of nuclear factor kappa-Β ligand (RANKL)/osteoprotegerin ratio in sera well reflected results of arthritis scores. Diurnal variation of STAT3 phosphorylation was suppressed in ZT0 group. At ZT2, expressions of IL-6/Interferon-γ/TNF/granulocyte-macrophage colony-stimulating factor in ZT0 group were significantly decreased as compared to untreated mice, though not in ZT12 group. In ZT0 group, IL-6 and TNF-α in sera were decreased for longer time than that in ZT12 group.

CONCLUSION

Chronotherapy using Baricitinib targeting cytokine secretions is effective in CIA mice. Clinical applications of chronotherapy can be expected to enhance the drug efficacy.

The Micro-Immunotherapy Medicine 2LARTH® Reduces Inflammation and Symptoms of Rheumatoid Arthritis In Vivo

Background

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease, which can cause cartilage and bone damages as well as pain and disability. In order to prevent disease progression, reduce pain, and major symptoms of RA, one good strategy consists in targeting proinflammatory cytokines that have the key role in the vicious circle of synovial inflammation and pain. The micro-immunotherapy medicine (MIM) 2LARTH® targets cytokines involved in inflammation.

Aim

The aim of the study is to evaluate the effect of the MIM compared to vehicle in an in vivo model of RA, induced in mice after immunization with articular bovine type II collagen.

Methods

Vehicle and MIM were dissolved in pure water (1 capsule in 100 ml) and 100 µl was given by gavage daily for 14 days. To evaluate the severity of arthritis, wrist and ankle thickness was determined, paw edema was measured, and a clinical score from 0 to 4 was established. Furthermore, histological analysis was performed. To evaluate systemic inflammation, circulating levels of IL-1β and TNF-α were measured by ELISA.

Results

Ankle thickness was found to be significantly reduced in MIM-treated mice compared to vehicle-treated mice (P < 0.05) and compared to untreated me (P < 0.05) and compared to untreated me (P < 0.05) and compared to untreated me (β and TNF-α were measured by ELISA. P < 0.05) and compared to untreated me (

Conclusion

The results indicate that the tested medicine reduces inflammation, histological, and clinical signs of RA in a CIA model.

Activation of Toll-Like Receptor 3 Induces Interleukin-1 Receptor Antagonist Expression by Activating the Interferon Regulatory Factor 3

Toll-like receptor 3 (TLR3) is a sensor of endogenous cell necrosis during the process of acute inflammation. Interleukin (IL)-1 receptor antagonist (IL-1Ra) is an anti-inflammatory cytokine and can negatively regulate the pathogenesis of inflammation. However, whether and how activation of TLR3 can regulate IL-1Ra expression has not been clarified. Here, we show that poly(I:C) induces IL-1Ra expression in primarily cultured human fibroblast-like synoviocytes and other types of cells. Induction of IL-1Ra by poly(I:C) was dependent on TLR3, but was independent of melanoma differentiation--associated protein 5 or retinoic acid-inducible gene I. Interferon regulatory factor 3 (IRF3) directly binds to the IL-1Ra promoter and promotes IL-1Ra expression in response to poly(I:C) stimulation. Induction of IL-1Ra by poly(I:C) was abolished by the inhibition of the NF-κB signaling, attenuated by the inhibition of the PI3K-Akt signaling, enhanced by inhibition of the ERK1/2 or MSK1/2 activation, but was independent of the p38 MAPK signaling. Treatment with poly(I:C) or Sendai virus elevated the levels of serum IL-1Ra in wild-type, but not in TLR3-/- or IRF3-/- mice. Our findings may provide new insights into the intrinsic anti-inflammatory function of TLR3 and double-stranded RNA-induced IL-Ra expression by TLR3 and its regulation.

Altered morpho-functional features of bones in autoimmune disease-prone BXSB/MpJ- Yaa mice

IMPACT STATEMENT

Bone disease, such as osteoporosis and rheumatoid arthritis, increases because of the progression of an aging society. Autoimmune disease are important and predisposing factors for the pathogenesis of the bone disease; however, the pathological mechanism is unclear. We have demonstrated that systemic autoimmune disease in BXSB/MpJ- Yaa is closely associated with the morpho-functional abnormalities of bones including bone marrow and has complicated pathology. The abnormalities are characterized by altered regulations of serum calcium, anemia tendency, and hematopoiesis with increased WBCs and decreased PLs, short length and low mass of long bones, imbalance in the populations of osteoclasts and osteoblasts, and increased expression of candidate genes for causing and/or exacerbating their phenotypes. Therefore, BXSB/MpJ- Yaa serves as a model to elucidate bone phenotypes in systemic autoimmune disease that would be affected by the factors in the bone as well as the other immune and/or mineral metabolism organs both in human and experimental medicine.

Interleukin-1β signaling in osteoarthritis - chondrocytes in focus

Osteoarthritis (OA) can be regarded as a chronic, painful and degenerative disease that affects all tissues of a joint and one of the major endpoints being loss of articular cartilage. In most cases, OA is associated with a variable degree of synovial inflammation. A variety of different cell types including chondrocytes, synovial fibroblasts, adipocytes, osteoblasts and osteoclasts as well as stem and immune cells are involved in catabolic and inflammatory processes but also in attempts to counteract the cartilage loss. At the molecular level, these changes are regulated by a complex network of proteolytic enzymes, chemokines and cytokines (for review: [1]). Here, interleukin-1 signaling (IL-1) plays a central role and its effects on the different cell types involved in OA are discussed in this review with a special focus on the chondrocyte.

Th17 in Animal Models of Rheumatoid Arthritis

IL-17-secreting helper CD4 T cells (Th17 cells) constitute a newly identified subset of helper CD4 T cells that play a key role in the development of rheumatoid arthritis (RA) in its animal models. Recently, several models of spontaneous RA, which elucidate the mechanism of RA onset, have been discovered. These animal models shed new light on the role of Th17 in the development of autoimmune arthritis. Th17 cells coordinate inflammation and promote joint destruction, acting on various cells, including neutrophils, macrophages, synovial fibroblasts, and osteoclasts. Regulatory T cells cannot control Th17 cells under conditions of inflammation. In this review, the pathogenic role of Th17 cells in arthritis development, which was revealed by the recent animal models of RA, is discussed.

Immunomodulatory Effect of Agave tequilana Evaluated on an Autoimmunity Like-SLE Model Induced in Balb/c Mice with Pristane

In this work, the immunomodulatory activity of the acetone extract and the fructans obtained from Agave tequilana were evaluated, on the systemic autoimmunity type-SLE model generated by the administration of 2,6,10,14-tetramethylpentadecane (TMPD, also known as pristane) on Balb/c female mice. The systemic autoimmunity type-SLE was observed seven months after the application of TMPD, in which the animals from the negative control group (animals with damage and without any other treatment) developed articular inflammation, proteinuria, an increment of the antinuclear antibody titters and tissue pro-inflammatory cytokines levels (IL-1β, IL-6, TNF-α e IFN-γ) as well as the anti-inflammatory cytokine IL-10. The administration of the different treatments and the extracts of A. tequilana, provoked the decrease of: articular inflammation, the development of proteinuria, ssDNA/dsDNA antinuclear antibody titters and cytokines IL-1β, IL-6, TNF-α, IFN-γ and IL-10. The phytochemical analysis of the acetone extract identified the presence of the following compounds: β-sitosterol glycoside; 3,7,11,15-tetramethyl-2-hexadecen-1-ol (phytol); octadecadienoic acid-2,3-dihydroxypropyl ester; stigmasta-3,5-dien-7-one; cycloartenone and cycloartenol. Therefore, A. tequilana contains active compounds with the capacity to modify the evolution of the systemic autoimmunity type-SLE on a murine model.

Deficiency in IL-1 Receptor Type 2 Aggravates K/BxN Serum Transfer-Induced Arthritis in Mice but Has No Impact on Systemic Inflammatory Responses

The biological activity of IL-1 is tightly regulated by the specific receptor antagonist (IL-1Ra) and the decoy receptor IL-1 receptor type 2 (IL-1R2). The role of IL-1Ra has been well demonstrated in IL-1Ra-deficient mice. In contrast, the role of endogenous IL-1R2 remains widely unknown. To define the functional role of endogenous IL-1R2 in the K/BxN serum transfer arthritis model and in IL-1β- or LPS-induced systemic inflammation in vivo, IL-1R2^-/- mice were created and compared with wild type mice. IL-1R2^-/- mice bred habitually and exhibited a normal phenotype. IL-1R2 deficiency aggravated arthritis severity and increased mRNA levels for key cytokines and chemokines such as IL-6, IL-1β, Cxcl-1, and Cxcl-2 significantly in ankles. There was no effect of IL-1R2 deficiency on the cell-autonomous cytokine response to IL-1β in the tested cell types, i.e., neutrophils, macrophages, and fibroblasts, but IL-1R2 deficiency on neutrophils increased the IL-1-induced response of fibroblasts in trans. Furthermore, IL-1β induced shedding of IL-1R2 in vivo. Inflammatory responses to IL-1β and LPS-induced mortality were not different in IL-1R2^-/- compared with wild type mice. Our data demonstrate that the decoy receptor IL-1R2 plays an important inhibitory role in local IL-1- and neutrophil-dependent tissue inflammation as shown in the K/BxN serum transfer arthritis model. In contrast to IL-1Ra, IL-1R2 appears to be less crucial for systemic responses to acute administration of IL-1 or LPS.

Potent Antiarthritic Properties of Phloretin in Murine Collagen-Induced Arthritis

In the exploration of potential therapeutic agents for rheumatoid arthritis (RA), DBA/1J mice are used as the RA model of collagen-induced arthritis (CIA). Phloretin, a flavonoid compound extracted from Prunus mandshurica, has been found to exhibit anti-inflammatory activity, making it a potential candidate for treatment of RA. The objective of this study was to evaluate the therapeutic effects of phloretin on CIA mice. CIA mice were dosed daily with phloretin at either 50 or 100 mg/kg among two treatment groups. CIA treated mice showed mitigation of clinical symptoms of RA in addition to reduced inflammation of hind-limbs compared to mice who did not receive phloretin. Histological analysis showed that phloretin suppressed the severity of RA and effectively mitigated joint inflammation and cartilage- and bone-destruction via reducing proinflammatory cytokine productions (TNF-α, IL-6, IL-1β, and IL-17). This was at least partially mediated by causing inadequate splenocyte activation and proliferation. Moreover, phloretin-treated CIA mice showed decreased oxidative stress and diminished levels of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) in paw tissues as well as reduced productivity of anti-collagen antibodies in serum. We have concluded that phloretin could be a potent and effective antiarthritis agent, demonstrating anti-inflammatory, antioxidative, and immunomodulatory effects in CIA mice.

The anti-inflammatory effect of triphala in arthritic-induced rats

CONTEXT

Triphala, an Indian Ayurvedic herbal formulation which contains Terminalia chebula Retz. (Combretaceae), Terminalia bellerica (Gaertn.) Roxb. (Combretaceae) and Emblica officinalis L. (Phyllanthaceae), is used for treating bowel-related complications, inflammatory disorders, and gastritis.

OBJECTIVE

To determine the anti-arthritic effect of triphala in arthritis-induced rats. For comparison purpose, the non-steroidal anti-inflammatory drug indomethacin was used.

MATERIALS AND METHODS

Arthritis was induced in Wistar albino rats by intradermal injection of complete Freund's adjuvant (0.1 ml) into the foot pad of right hind paw. Triphala (100 mg/kg b wt, i.p.) was administered from day 11 to 18 after the administration of complete Freund's adjuvant. The activities/levels of lysosomal enzymes, glycoproteins, antioxidant status, and lipid peroxidation were determined in the paw tissues of arthritic rats. In addition, the inflammatory mediators were also measured in both the serum and the paw tissue of arthritic rats.

RESULTS

The levels/activities of lipid peroxidation (∼41.5%), glycoproteins (hexose ∼43.3%, hexosamine ∼36.5%, and sialic acid ∼33.7%), lysosomal enzymes (acid phosphatase ∼52.4%, β-galactosidase ∼22.9%, N-acetyl β-glucosaminidase ∼22.1%, and cathepsin-D ∼27.7%) were found to be decreased and the antioxidant status (SOD ∼75.6%, CAT ∼62.7%, GPx ∼55.8%, GST ∼82.1%, and GSH ∼72.7%) was increased in the paw tissues of triphala-treated arthritic rats. In addition, the inflammatory mediator levels in serum (TNF-α ∼75.5%, IL-1β ∼99%, VEGF ∼75.2%, MCP-1 ∼76.4%, and PGE2 ∼69.9%) and in paw tissues (TNF-α ∼71.6%, IL-1β ∼75.5%, VEGF ∼55.1%, MCP-1 ∼69.1%, and PGE2 ∼66.8%) were found to be suppressed.

CONCLUSION

Triphala has a promising anti-inflammatory effect in the inflamed paw of arthritis-induced rats.

Experimental transmission of AA amyloidosis by injecting the AA amyloid protein into interleukin-1 receptor antagonist knockout (IL-1raKO) mice

The incidence of AA amyloidosis is high in humans with rheumatoid arthritis and several animal species, including cats and cattle with prolonged inflammation. AA amyloidosis can be experimentally induced in mice using severe inflammatory stimuli and a coinjection of AA amyloid; however, difficulties have been associated with transmitting AA amyloidosis to a different animal species, and this has been attributed to the "species barrier." The interleukin-1 receptor antagonist knockout (IL-1raKO) mouse, a rodent model of human rheumatoid arthritis, has been used in the transmission of AA amyloid. When IL-1raKO and BALB/c mice were intraperitoneally injected with mouse AA amyloid together with a subcutaneous pretreatment of 2% AgNO3, all mice from both strains that were injected with crude or purified murine AA amyloid developed AA amyloidosis. However, the amyloid index, which was determined by the intensity of AA amyloid deposition, was significantly higher in IL-1raKO mice than in BALB/c mice. When IL-1raKO and BALB/c mice were injected with crude or purified bovine AA amyloid together with the pretreatment, 83% (5/6 cases) and 38% (3/8 cases) of IL-1raKO mice and 17% (1/6 cases) and 0% (0/6 cases) of BALB/c mice, respectively, developed AA amyloidosis. Similarly, when IL-1raKO and BALB/c mice were injected with crude or purified feline AA amyloid, 33% (2/6 cases) and 88% (7/8 cases) of IL-1raKO mice and 0% (0/6 cases) and 29% (2/6 cases) of BALB/c mice, respectively, developed AA amyloidosis. These results indicated that IL-1raKO mice are a useful animal model for investigating AA amyloidogenesis.

The calcification potential of human MSCs can be enhanced by interleukin-1β in osteogenic medium

Inflammation is one of the key regulators of the repair process in bone tissues. Current data about the effect of interleukin-1β (IL-1β) on MSCs and osteoblasts are conflicting. We investigated the long-term effect of IL-1β on direct osteogenic differentiation of hMSCs in vitro. IL-1β-stimulated cells showed enhanced proliferation and entered maturation prior to non-stimulated ones, as monitored by ALP activity. The process of calcification was accelerated during long-term stimulation of hMSCs with IL-1β. Since donor variability is a well-known issue, we suggest a new method to illustrate global changes of a random chosen donor population through collative analysis. We further demonstrate an absorbance assay to evaluate the degree of calcification during in vitro culture of monolayer expanded hMSCs. Our findings support the importance of IL-1β in osteogenic differentiation of hMSCs in an in vitro monolayer culture model. A new online absorbance assay is a useful method to evaluate the osteogenic differentiation of hMSCs at early stages. These findings will be helpful in optimizing predifferentiation of hMSCs in vitro for bone tissue engineering. Copyright © 2014 John Wiley & Sons, Ltd.

Dietary trans-10,cis-12 CLA reduces murine collagen-induced arthritis in a dose-dependent manner

Dietary trans-10,cis-12 (t10c12) conjugated linoleic acid (CLA) has been shown to reduce inflammation in a murine collagen-induced arthritis (CA) model. To understand the anti-inflammatory potential of t10c12-CLA in the diet, the minimum dose of pure dietary t10c12-CLA capable of reducing CA was investigated. Because plasma inflammatory cytokines often do not reflect the progression of late-stage arthritis, inflamed tissue cytokine concentrations were also investigated in relation to increasing dietary t10c12-CLA amounts. Mice were randomly assigned to the following dietary treatments upon the establishment of arthritis: corn oil (CO) or 0.125%, 0.25%, 0.375%, or 0.5% t10c12-CLA (wt:wt) for 84 d. Sham mice (no arthritis) were fed CO and served as controls. Arthritic paw score, based on subjective assessment of arthritic severity, and paw thickness decreased linearly overall [16-65% (P < 0.001) and 0.5-12% (P < 0.001), respectively] as dietary t10c12-CLA increased (P < 0.001, R(2) < 0.81). Increasing dietary t10c12-CLA was associated with a decrease in plasma interleukin (IL)-1β at days 21 and 42 compared with CO-fed arthritic mice, such that mice fed ≥0.25% t10c12-CLA had IL-1β concentrations that were similar to sham mice. Plasma cytokines returned to sham mice concentrations by day 63 regardless of treatment; however, an arthritis-induced elevation in paw IL-1β decreased linearly as dietary t10c12-CLA concentrations increased at day 84 (P = 0.007, R(2) = 0.92). Similarly, increasing dietary t10c12-CLA linearly decreased paw tumor necrosis factor (TNF)-α (P = 0.05, R(2) = 0.70). In conclusion, ≥0.125% t10c12-CLA dose-dependently reduced inflammation in a murine CA model.

Efficient induction of arthritis in mice by an arthritogenic 4-clone cocktail of anti-type II collagen monoclonal antibodies recognizing different epitopes of the antigen

We previously reported that a combination of 4 monoclonal antibodies (mAbs) (cocktail A) to type II collagen (CII), including immunoglobulin G (IgG)2b (C2B-9 and C2B-14) and IgG2a (C2A-7 and C2A-12), induced arthritis in DBA/1J mice. In this study, we found that C2B-9 and C2A-7 as well as C2B-14 and C2A-12 recognized the same or similar epitopes on CII. Based on these data, we hypothesized that the combination of more than 3 mAbs recognizing different epitopes on CII may more efficiently induce arthritis. Therefore, in addition to C2B-9 and C2B-14, which show high binding activity to CII compared with C2A-7 and C2A-12, we developed two more mAbs including IgG2b (C2B-17) and IgG2a (C2A-16), to make a new cocktail (cocktail B) consisting of these 4 mAbs. To compare the ability of cocktail B to induce arthritis with cocktail A, DBA/1J mice were injected with these cocktails. The results showed that cocktail B was able to induce more severe arthritis than cocktail A, especially more markedly affecting rear paws. Histologically, there was more marked proliferation of synovial tissues, massive infiltration by inflammatory cells, and severe destruction of cartilage and bone in mice treated with cocktail B than with cocktail A. Collectively, the new combination of 4 mAbs recognizing different respective epitopes appears to effectively induce arthritis in mice. Thus, the results may provide insights into the selection of mAbs associated with the development of arthritis.

Natural killer cells and their role in rheumatoid arthritis: friend or foe?

Rheumatoid arthritis (RA) is a long-term disease that leads to inflammation of the joints and surrounding tissues. Natural killer (NK) cells are an important part of the innate immune system and are responsible for the first line of defense against pathogens during the initial immune challenge before the adaptive immune system eventually eliminates the infectious burden. NK cells have the capacity to damage normal cells or through interaction with other cells such as dendritic cells, macrophages, and T cells cause autoimmune diseases, such as RA. NK cells isolated from the joints of patients with RA suggest that they may play a role in this disease. However, the involvement of NK cells in RA pathology is not fully elucidated. Both protective and detrimental roles of NK cells in RA have recently been reported. A better understanding of NK cells' role in RA might help to develop new therapeutic strategies for treatment of the RA or other autoimmune diseases. We have decided in this paper to focus on the NK cell biology, and attempt to bring the interested readership of this Journal up to date on the NK cell, specifically its possible relation to RA.

Toxoplasma gondii infection inhibits Th17-mediated spontaneous development of arthritis in interleukin-1 receptor antagonist-deficient mice

Interleukin 1 receptor antagonist (IL-1Ra)-deficient BALB/c mice develop spontaneous arthritis resembling human rheumatoid arthritis. We herein report that infection with Toxoplasma gondii, an intracellular protozoan, is capable of ameliorating the spontaneous development of arthritis in IL-1Ra-deficient mice. The onset of arthritis development was delayed and the severity score of arthritis was significantly suppressed in T. gondii-infected mice. Expression of IL-12p40 mRNA from CD11c(+) cells of mesenteric lymph nodes (mLN) and spleen markedly increased at 1 week after peroral infection. While CD11c(+) cells also produced IL-10, IL-1β, and IL-6, CD4(+) T cells from T. gondii-infected mice expressed significantly high levels of T-bet and gamma interferon (IFN-γ) mRNA in both mLN and spleen. Levels of GATA-3/IL-4 mRNA or RORγt/IL-17 mRNA decreased in the infected mice, indicating Th1 cell polarization and the reduction of Th2 and Th17 cell polarization. The severity of arthritis was related to Th1 cell polarization accompanied by Th17 cell reduction, demonstrating the protective role of the T. gondii-derived Th1 response against Th17 cell-mediated arthritis in IL-1Ra-deficient mice.

Inhibition of adjuvant arthritis in rats by electroporation with interleukin-1 receptor antagonist

To assess the protective effects of the cytokine inhibitor interleukin-1 receptor antagonist (IL-1ra) on gene induction, an electroporation technique to treat adjuvant-induced arthritis (AIA) in rats was established, and its advantage was estimated in the present study. Electroporation with human IL-1ra was performed in Lewis rats before and after induction of AIA. Local inflammation was evaluated by monitoring hind paw swelling, whereas histological evaluations were performed using paraffin embedded sections of hind paw specimens stained with hematoxylin and eosin. In addition, serum IL-1? levels were analyzed using an enzyme-linked immunosorbent assay. Induction of IL-1ra by our electroporation method inhibited systematic body weight loss and enhancement of local inflammation after intradermal injection of heat-killed Mycobacterium tuberculosis. Notably, IL-1ra electroporation reduced paw swelling, inflammation, and bone erosion scores in embedded sections and serum IL-1? levels induced in AIA rats. The IL-1ra gene induction using the present electroporation technique inhibited local and systematic inflammation in AIA rats. These results indicate that this method may represent a novel pharmacotherapy strategy for arthritis.

Rodent preclinical models for developing novel antiarthritic molecules: comparative biology and preferred methods for evaluating efficacy

Rodent models of immune-mediated arthritis (RMIA) are the conventional approach to evaluating mechanisms of inflammatory joint disease and the comparative efficacy of antiarthritic agents. Rat adjuvant-induced (AIA), collagen-induced (CIA), and streptococcal cell wall-induced (SCW) arthritides are preferred models of the joint pathology that occurs in human rheumatoid arthritis (RA). Lesions of AIA are most severe and consistent; structural and immunological changes of CIA best resemble RA. Lesion extent and severity in RMIA depends on experimental methodology (inciting agent, adjuvant, etc.) and individual physiologic parameters (age, genetics, hormonal status, etc.). The effectiveness of antiarthritic molecules varies with the agent, therapeutic regimen, and choice of RMIA. All RMIA are driven by overactivity of proinflammatory pathways, but the dominant molecules differ among the models. Hence, as with the human clinical experience, the efficacy of various antiarthritic molecules differs among RMIA, especially when the agent is a specific cytokine inhibitor.

CXC chemokine receptor 4 expressed in T cells plays an important role in the development of collagen-induced arthritis

Introduction

Chemokines and their receptors are potential therapeutic targets in rheumatoid arthritis (RA). Among these, several studies suggested the involvement of CXC chemokine 4 (CXCR4) and its ligand CXC ligand 12 (SDF-1) in RA pathogenesis. However, the role of these molecules in T-cell function is not known completely because of embryonic lethality of Cxcr4- and Cxcl12-deficient mice. In this report, we generated T cell-specific Cxcr4-deficient mice and showed that the CXCR4 in T cells is important for the development of collagen-induced arthritis (CIA).

Methods

T cell-specific Cxcr4-deficient mice were generated by using the Cre-loxP system. Mice harboring loxP sites flanking exon 2 of the Cxcr4gene (Cxcr4^flox/flox) were generated by homologous recombination and crossed with Cre transgenic mice expressing Cre recombinase under the control of Lck promoter (Cxcr4^+/+/Lck-Cremice) to generate T cell-specific Cxcr4-deficient mice (Cxcr4^flox/flox/Lck-Cre mice). CIA was induced by immunization with chicken type II collagen and Complete Freund's Adjuvant (CFA).

Results

The incidence, but not the severity, of CIA was significantly reduced in Cxcr4^flox/flox/Lck-Cre mice compared with Cxcr4^+/+/Lck-Cre mice. We found that the expression of CXCR4 was enhanced in activated T cells, and the migration of Cxcr4-deficient T cells toward SDF-1 was severely impaired. However, antibody production, cellular proliferative response, and cytokine production on treatment with type II collagen (IIC) were normal in these knockout mice, suggesting that CXCR4 is not involved in T-helper functions. Interestingly, the proportion of CXCR4-expressing T cells was much increased in affected joints compared with that in draining lymph nodes in CIA-induced mice, and distribution of Cxcr4^flox/flox/Lck-Cre mouse-derived T cells into affected joints was suppressed compared with that in Cxcr4^+/+/Lck-Cre T cells.

Conclusions

These results indicate that CXCR4 expression in T cells is important for the development of CIA, by recruiting activated T cells toward inflammatory sites, and suggest that CXCR4 is a good target for the treatment of RA in humans.

Interleukin-1β and interleukin-6 in arthritis animal models: roles in the early phase of transition from acute to chronic inflammation and relevance for human rheumatoid arthritis

Tumor necrosis factor-α (TNF-α) is the major target of the therapeutic approach in rheumatoid arthritis. A key issue in the approach to chronic arthritis is the understanding of the crucial molecules driving the transition from the acute phase to the chronic irreversible phase of the disease. In this review we analyzed five experimental arthritis animal models (antigen-induced arthritis, adjuvant-induced arthritis, streptococcal cell wall arthritis, collagen-induced arthritis and SKG) considered as possible scenarios to facilitate interpretation of the biology of human rheumatoid arthritis. The SKG model is strictly dependent on interleukin (IL)-6. In the other models, IL-1β and IL-6, more than TNF-α, appear to be relevant in driving the transition, which suggests that these should be the targets of an early intervention to stop the course toward the chronic form of the disease.

IL-1 plays an important role in the bone metabolism under physiological conditions

It is well known that IL-1 is involved in bone resorption under pathological conditions. The role of this cytokine in bone remodeling under physiological conditions, however, remains obscure. In this study, we addressed the role of IL-1 in physiological bone metabolism through analyses of IL-1α-deficient (KO), IL-1β KO and IL-1α/β double KO mice that were housed under specific pathogen free conditions. The femur mineral density, trabecular bone mass and cortical thickness significantly increased in all KO mice compared with wild-type (WT) mice. The number of osteoclasts in trabecular bones decreased, suggesting that IL-1 regulates bone metabolism through regulation of osteoclast formation. When differentiation of bone marrow (BM) cells into osteoclasts was induced by parathyroid hormone in co-cultures of osteoblasts and BM cells from WT and IL-1α/β KO mice, IL-1α/β KO BM cell co-cultures failed to undergo efficient osteoclast-like multinucleated cell (OCL) differentiation, although high levels of receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL) was induced. In contrast, efficient OCL differentiation was observed in IL-1α/β KO osteoblast/WT BM cell co-cultures, in which high levels of IL-1α/β and low levels of RANKL were produced. Addition of IL-1α to IL-1α/β KO BM-derived macrophage cultures markedly enhanced OCL differentiation induced by soluble RANKL, and the downstream molecules of receptor activator of NF-κB (RANK) including c-Jun N-terminal factor, extracellular signal-regulated kinase and c-Fos were less activated in the absence of IL-1 upon treatment with RANKL. Taken together, these results indicate that IL-1 directly activates RANK signaling other than inducing RANKL to promote osteoclastogenesis and plays an important role in physiological bone metabolism.

Identification of the cellular sensor that stimulates the inflammatory response to sterile cell death

Cell death provokes a robust inflammatory response. We have previously shown that this response is dependent on IL-1alpha. In this study, we investigate the cellular mechanism used by a host to sense cell death, produce IL-1alpha and also the role of IL-1beta in this response. In almost all cases examined, the IL-1 that stimulated the death-induced inflammatory response came from the host rather than the cell that was dying. In these situations, host bone marrow-derived cells were the key source of the IL-1alpha that was required for the inflammatory response. Conditional cellular depletion and reconstitution in CD11b promoter-driven diphtheria toxin receptor transgenic mice revealed that host macrophages played an essential role in the generation of the inflammatory response and were the source of the required IL-1alpha. In addition, we found a role for IL-1beta in the death-induced inflammatory response and that this cytokine was generated by both bone marrow-derived and radioresistant host cells. The one exception to these findings was that when dendritic cells were injected into mice, they provided a portion of the IL-1 that stimulated inflammation, and this was observed whether the dendritic cells were live or necrotic. Together, these findings demonstrate that macrophages play a key role as the primary sentinels that are required to sense and report cell death in ways that initiate the inflammatory response. One key way they accomplish this important task is by producing IL-1alpha that is needed to initiate the inflammatory response.

Nucleoprotein Diet Ameliorates Arthritis Symptoms in Mice Transgenic for Human T-Cell Leukemia Virus Type I (HTLV-1)

Because rheumatoid arthritis (RA), an autoimmune disease, the patients often recognize side-effects due to the medication, alternative therapeutic strategies might potentially offer a clinical advantage. We evaluated the effect of nucleoprotein from salmon soft roe on animal model of arthritis. Mice transgenic for human T-cell leukemia virus type I (HTLV-1 Tg) were divided into three experimental groups and supplemented on either nucleoprotein-free (nonNP), or 0.6% or 1.2% nucleoprotein mixed (NP0.6 or NP1.2) diet for 3 months. The mice were evaluated arthritis by morphology, and measured with rheumatoid factor (RF). Moreover, macrophages and oxidative metabolites were assessed in the ankle and/or serum. Anti-oxidative potentials in nucleoprotein were determined with biological anti-oxidative potential (BAP) test, and electron spin resonance (ESR) analysis. NonNP-diet HTLV-1 Tg mice increased an arthritis symptoms and RF. The symptoms were ameliorated in NP-diet groups. Macrophages detected by F4/80 staining, and oxidative metabolites in the serum and/or joints were clearly decreased in 1.2% NP-diet HTLV-1 Tg mice. Nucleoprotein and DNA-nucleotide, but less protamine, had direct anti-oxidative potency with BAP test and/or ESR in vitro. These observations suggest that dietary nucleoprotein ameliorates arthritis symptoms in HTLV-1 Tg mice and offers hope as an alternative treatment for this debilitating medical condition.

MSK1 regulates the transcription of IL-1ra in response to TLR activation in macrophages

The activity of the pro-inflammatory cytokine IL (interleukin)-1 is closely regulated in vivo via a variety of mechanisms, including both the control of IL-1 production and secretion as well as naturally occurring inhibitors of IL-1 function, such as IL-1ra (IL-1 receptor antagonist). IL-1ra is homologous with IL-1, and is able to bind but not activate the IL-1 receptor. IL-1ra can be produced by a variety of cell types, and its production is stimulated by inflammatory signals. In the present study, we show that in macrophages the TLR (Toll-like receptor)-mediated induction of IL-1ra from both its proximal and distal promoters involves the p38 and ERK1/2 (extracellular-signal-regulated kinase 1/2) MAPK (mitogen-activated protein kinase) cascades. In addition, we show that MSK1 and 2 (mitogen- and stress-activated kinase 1 and 2), kinases activated by either ERK1/2 or p38 in vivo, are required for the induction of both IL-1ra mRNA and protein. MSKs regulate IL-1ra transcription via both IL-10-dependent and -independent mechanisms in cells. Consistent with this, knockout of MSK in mice was found to result in a decrease in IL-1ra production following LPS (lipopolysaccharide) injection. MSKs therefore act as important negative regulators of inflammation following TLR activation.

Alpha9 integrin and its ligands constitute critical joint microenvironments for development of autoimmune arthritis

Osteopontin is critically involved in rheumatoid arthritis; however, the molecular cross-talk between osteopontin and joint cell components that leads to the inflammatory joint destruction is largely unknown. We found that not only osteopontin but also tenascin-C and their common receptor, alpha(9) integrin, are expressed at arthritic joints. The local production of osteopontin and tenascin-C is mainly due to synovial fibroblasts and, to a lesser extent, synovial macrophages. Synovial fibroblasts and macrophages express alpha(9) integrin, and autocrine and paracrine interactions of alpha(9) integrin on synovial fibroblasts and macrophages and its ligands contribute differently to the production of proinflammatory cytokines and chemokines. alpha(9) integrin is also involved in the recruitment and accumulation of inflammatory cells. Inhibition of alpha(9) integrin function with an anti-alpha(9) integrin Ab significantly reduces the production of arthrogenic cytokines and chemokines and ameliorates ongoing arthritis. Thus, we identified alpha(9) integrin as a critical intrinsic regulator that controls the development of autoimmune arthritis.

Interleukin-1 receptor antagonist gene polymorphisms are associated with disease severity in Black South Africans with rheumatoid arthritis

OBJECTIVE

To test for genetic associations between polymorphisms of the interleukin-1 (IL-1) gene cluster and disease susceptibility and severity in Black South Africans with rheumatoid arthritis (RA).

METHODS

Allele and genotype frequencies of IL1B (-511) and (+3954) and IL1RN variable number of tandem repeat (VNTR) and (+2018) were compared between 141 RA patients and 101 healthy controls.

RESULTS

No significant differences in allelic distribution at the four loci were observed between RA patients and controls. Within the RA group, the IL1RN*2 (two repeats of an 86bp tandem repeat) at the IL1RN VNTR locus was independently associated with higher Larsen radiologic damage scores (LDS), corrected for disease duration (p=0.04). Moreover, the inferred haplotype, consisting of IL1RN*2 and (+2018) 'C' allele, was associated with significantly higher LDS, on average 15 points higher, compared to the base haplotype of IL1RN*long (three or more repeats) and (+2018) 'T' allele (p=0.009). The common IL1B (-511) 'T' allele was associated with a poorer modified health assessment questionnaire disability index (p=0.02).

CONCLUSION

Our findings provide further evidence of a possible role of polymorphisms of the IL-1 gene cluster in disease severity in RA, and particularly IL1RN*2 as a marker of erosive joint damage in Black South Africans with RA.

Gene signatures reflect the marked heterogeneity of tissue-resident macrophages

Tissue-resident macrophages play an important role in defense against pathogens and perform key functions in organ homeostasis, innate and adaptive immunity. Tissue macrophages originate from blood monocytes that infiltrate virtually every organ in the body. Macrophages in different tissues share many characteristics, including their ability to migrate, phagocytose particles, metabolize lipids and present antigens. Morphologically they are quite heterogeneous, and some distinct functions have been reported. The gene expression profile of macrophages is reflective of both their shared and distinct biological functions. Here, we show that macrophages from murine spleen, liver and peritoneum display dramatically different expression profiles. Clusters of genes were found to represent unique biological functions related to adhesion, antigen presentation, phagocytosis, lipid metabolism and signal transduction. Some gene families, such as integrins, are differentially expressed among the macrophages resident in different tissues, suggesting that the tissue of residence influences their biological function.

Anti-type II collagen antibody accelerates arthritisvia CXCR2-expressing cells in IL-1 receptor antagonist-deficient mice

Arthritis can be induced in mice by the injection of anti-type II collagen (anti-CII) Ab and LPS. To elucidate the role of IL-1 receptor antagonist (IL-1ra) in Ab-induced arthritis, WT and IL-1ra(-/-) mice were administered anti-CII Ab and LPS. These IL-1ra(-/-) mice developed severe arthritis even at low doses of anti-CII Ab and LPS, while WT mice did not. The cells that invaded the arthritic joints were mainly Gr-1(+) neutrophils, and the number of the cells in the joints remained high over 4 weeks in the IL-1ra(-/-) mice. KC, a ligand for CXCR2, is found in higher levels in the arthritic paws of IL-1ra(-/-) mice compared with the WT, and most of the cells that infiltrated into the joints of the IL-1ra(-/-) mice were CXCR2-expressing neutrophils. Administration of anti-CXCR2 Ab completely inhibited arthritis development. The anti-CXCR2 Ab decreased the number of neutrophils in the blood and also inhibited the migration of neutrophils to KC. These results suggested that the high susceptibility of IL-1ra(-/-) mice to anti-CII Ab-induced arthritis was due to the higher expression of chemotactic factors like KC and the sustained infiltration of CXCR2-expressing neutrophils into the joints.

Curcumin and autoimmune disease

The immune system has evolved to protect the host from microbial infection; nevertheless, a breakdown in the immune system often results in infection, cancer, and autoimmune diseases. Multiple sclerosis, rheumatoid arthritis, type 1 diabetes, inflammatory bowel disease, myocarditis, thyroiditis, uveitis, systemic lupus erythromatosis, and myasthenia gravis are organ-specific autoimmune diseases that afflict more than 5% of the population worldwide. Although the etiology is not known and a cure is still wanting, the use of herbal and dietary supplements is on the rise in patients with autoimmune diseases, mainly because they are effective, inexpensive, and relatively safe. Curcumin is a polyphenolic compound isolated from the rhizome of the plant Curcuma longa that has traditionally been used for pain and wound-healing. Recent studies have shown that curcumin ameliorates multiple sclerosis, rheumatoid arthritis, psoriasis, and inflammatory bowel disease in human or animal models. Curcumin inhibits these autoimmune diseases by regulating inflammatory cytokines such as IL-1beta, IL-6, IL-12, TNF-alpha and IFN-gamma and associated JAK-STAT, AP-1, and NF-kappaB signaling pathways in immune cells. Although the beneficial effects of nutraceuticals are traditionally achieved through dietary consumption at low levels for long periods of time, the use of purified active compounds such as curcumin at higher doses for therapeutic purposes needs extreme caution. A precise understanding of effective dose, safe regiment, and mechanism of action is required for the use of curcumin in the treatment of human autoimmune diseases.

Enhanced susceptibility to immune nephritis in DBA/1 mice is contingent upon IL-1 expression

The DBA/1 mouse strain is particularly sensitive to experimental immune-mediated nephritis. Previous studies have indicated that various chemokines/cytokines are elevated in strains of mice susceptible to immune-mediated glomerulonephritis. One of the many elevated cytokines is IL-1. This study was designed to determine if IL-1 is essential for the development of immune-mediated nephritis in the DBA/1 mouse strain that is particularly sensitive to this disease. Both male and female DBA/1 mice and DBA/1.IL-1R1(-/-) mice were challenged with anti-GBM sera. We then compared DBA/1 mice to DBA/1.IL-1R1(-/-) mice to determine the influence of IL-1 on immune-mediated nephritis. Compared to DBA/1 mice, DBA/1.IL-1R1(-/-) mice excreted significantly less protein post anti-GBM serum challenge. None of the DBA/1.IL-1R1(-/-) mice, male or female, had a BUN higher than 22 mg/dl post-challenge whereas wild-type DBA/1 mice had significantly elevated BUN. Wild-type DBA/1 mice exhibited pronounced glomerulonephritis, with crescent formation, as well as tubulo-interstitial disease compared to DBA/1.IL1R1(-/-) mice. These findings indicate that IL-1 is necessary for the development of nephritis in DBA/1 mice and suggest that the elevated IL-1 levels in these mice may be one reason why the DBA/1 strain is particularly sensitive to multiple end organ diseases.

(S)-1-((S)-2-{[1-(4-amino-3-chloro-phenyl)-methanoyl]-amino}-3,3-dimethyl-butanoyl)-pyrrolidine-2-carboxylic acid ((2R,3S)-2-ethoxy-5-oxo-tetrahydro-furan-3-yl)-amide (VX-765), an orally available selective interleukin (IL)-converting enzyme/caspase-1 inhibitor, exhibits potent anti-inflammatory activities by inhibiting the release of IL-1beta and IL-18

(S)-1-((S)-2-{[1-(4-amino-3-chloro-phenyl)-methanoyl]-amino}-3,3-dimethyl-butanoyl)-pyrrolidine-2-carboxylic acid ((2R,3S)-2-ethoxy-5-oxo-tetrahydro-furan-3-yl)-amide (VX-765) is an orally absorbed prodrug of (S)-3-({1-[(S)-1-((S)-2-{[1-(4-amino-3-chlorophenyl)-methanoyl]-amino}-3,3-dimethyl-butanoyl)-pyrrolidin-2yl]-methanoyl}-amino)-4-oxo-butyric acid (VRT-043198), a potent and selective inhibitor of interleukin-converting enzyme/caspase-1 subfamily caspases. VRT-043198 exhibits 100- to 10,000-fold selectivity against other caspase-3 and -6 to -9. The therapeutic potential of VX-765 was assessed by determining the effects of VRT-043198 on cytokine release by monocytes in vitro and of orally administered VX-765 in several animal models in vivo. In cultures of peripheral blood mononuclear cells and whole blood from healthy subjects stimulated with bacterial products, VRT-043198 inhibited the release of interleukin (IL)-1beta and IL-18, but it had little effect on the release of several other cytokines, including IL-1alpha, tumor necrosis factor-alpha, IL-6 and IL-8. In contrast, VRT-043198 had little or no demonstrable activity in cellular models of apoptosis, and it did not affect the proliferation of activated primary T cells or T-cell lines. VX-765 was efficiently converted to VRT-043198 when administered orally to mice, and it inhibited lipopolysaccharide-induced cytokine secretion. In addition, VX-765 reduced disease severity and the expression of inflammatory mediators in models of rheumatoid arthritis and skin inflammation. These data suggest that VX-765 is a novel cytokine inhibitor useful for treatment of inflammatory diseases.