Dopamine D2-like receptor signaling suppresses human osteoclastogenesis

Dopamine, a major neurotransmitter, transmits signals via five different seven-transmembrane G protein-coupled receptors termed D1 to D5. Although the relevance of neuroendocrine system to bone metabolism has been emerging, the precise effects of dopaminergic signaling upon osteoclastogenesis remain unknown. Here, we demonstrate that human monocyte-derived osteoclast precursor cells express all dopamine-receptor subtypes. Dopamine and dopamine D2-like receptor agonists such as pramipexole and quinpirole reduced the formation of TRAP-positive multi-nucleated cells, cathepsin K mRNA expression, and pit formation area in vitro. These inhibitory effects were reversed by pre-treatment with a D2-like receptor antagonist haloperidol or a Gαi inhibitor pertussis toxin, but not with the D1-like receptor antagonist SCH-23390. Dopamine and dopamine D2-like receptor agonists, but not a D1-like receptor agonist, suppressed intracellular cAMP concentration as well as RANKL-meditated induction of c-Fos and NFATc1 mRNA expression in human osteoclast precursor cells. Finally, the dopamine D2-like receptor agonist suppressed LPS-induced osteoclast formation in murine bone marrow culture ex vivo. These findings indicate that dopaminergic signaling plays an important role in bone homeostasis via direct effects upon osteoclast differentiation and further suggest that the clinical use of neuroleptics is likely to affect bone mass.

[JAK inhibitor]

Biologics targeting inflammatory cytokine has become a standardized tool for remission induction in rheumatoid arthritis (RA). However, it is handled under restricted conditions and their cost of acquisition is high. Small molecule drugs targeting Janus kinase (JAK), a molecule involved in intracellular signaling pathway has shown similar treatment effect as biologics. Moreover, inhibitory effect on bone destruction has been demonstrated and has been approved in 2012 as a new disease modifying anti-rheumatic drug in USA. However, since the inhibition of JAK results in inhibition of multiple cytokine signaling pathways, the clinical studies have also shown adverse events differing from biologics.

Janus kinase inhibitors in autoimmune diseases

Biological therapies directed at proinflammatory cytokines have irrevocably changed the landscape of treatment of rheumatoid arthritis (RA) and other autoimmune diseases. With the advances in our knowledge in cytokine signalling, the question emerges whether targeting intracellular signalling might also be a safe and efficacious strategy. Janus kinases or Jaks are critical for a large family of cytokines and the first Jak inhibitors has been approved by the FDA. It is therefore timely to consider this new category of drugs and reflect on their potential roles, present and future, in the treatment of RA and related disorders.

[Regulation of osteoclastogenesis by human mesenchymal stem cells leading to application of a novel treatment for rheumatoid arthritis]

Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease characterized by synovitis and bone destruction leading to irreversible joint deformity. The development of a novel treatment for RA aiming at joint repair is necessary. Recently, mesenchymal stem cells (MSCs) have been widely studied as a new therapeutic tool for the treatment of RA, due to their multipotency and also their immunosuppressive properties. We show here that MSCs inhibit osteoclast differentiation depending on the constitutive production of osteoprotegerin, a decoy receptor of receptor activator of nuclear factor kappa-B ligand (RANKL). Our results further indicate that MSCs are useful in RA treatment by preventing the progression of bone damage by inhibiting osteoclast differentiation. In addition, MSCs are likely to play important roles in bone metabolism and maintenance of joint formation. In conclusion, MSC is a promising tool for both anti-inflammation and bone repair for RA patients.

Interleukin-1β induces differentiation of human mesenchymal stem cells into osteoblasts via the Wnt-5a/receptor tyrosine kinase-like orphan receptor 2 pathway

OBJECTIVE

Mesenchymal stem cells (MSCs) are considered to be a novel tool for the treatment of rheumatoid arthritis (RA) because of their multipotency to differentiate into osteoblasts and chondrocytes, their immunosuppressive effects, and availability. The aim of this study was to assess the mechanisms of human MSC differentiation into osteoblasts under inflammatory conditions.

METHODS

Human MSCs were cultured in commercialized osteogenic induction medium with inflammatory cytokines for up to 10 days. Osteoblast differentiation was detected by alkaline phosphatase staining and messenger RNA (mRNA) expression of multiple osteoblast markers. Mineralization was assessed by alizarin red S staining.

RESULTS

Among the various cytokines tested, interleukin-1β (IL-1β) induced differentiation of human MSCs into osteoblasts, which was confirmed by alkaline phosphatase activity, expression of RUNX2 mRNA, and strong alizarin red S staining. Among various molecules of the Wnt family, Wnt-5a and receptor tyrosine kinase-like orphan receptor 2 (Ror2), a major receptor of Wnt-5a, were significantly induced in human MSCs by IL-1β. Silencing of either WNT5A or ROR2 by small interfering RNA with 2 different sequences reduced alkaline phosphatase activity, RUNX2 expression, and alizarin red S staining of human MSCs induced by IL-1β.

CONCLUSION

IL-1β effectively and rapidly induced human MSC differentiation into osteoblasts and mineralization, mainly through the noncanonical Wnt-5a/Ror2 pathway. These results suggest potential benefits of IL-1β-treated human MSCs in the treatment of damaged bone as well as in the induction of self-renewal and self-repair of damaged tissue, including osseous tissue.

Dermal mast cell density in fingers reflects severity of skin sclerosis in systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is characterized by skin sclerosis, which develops from the distal extremities and spreads to the trunk. Although several reports have implied the involvement of mast cells in SSc based on examination of forearm skin specimens, there have been no studies that examined digital skin specimens.

METHODS

Skin biopsies were obtained from the distal one-third of the forearm and between distal and proximal interphalangeal joints from 46 SSc patients, as well as from 29 non-SSc patients and normal controls. Dermal mast cells were detected histologically using NanoZoomer digital pathology.

RESULTS

Dermal mast cell density was significantly higher in both the forearms and fingers in SSc patients compared with non-SSc patients and normal controls. Digital dermal mast cell density was significantly higher in patients with diffuse cutaneous SSc than in local cutaneous SSc patients and also in the anti-topoisomerase I antibody-positive group than in the negative group, though such tendency was not noted in the forearm dermis. Interestingly, digital dermal mast cell density tended to correlate negatively but significantly with disease duration, suggesting the possible involvement of dermal mast cells in the early pathological process.

CONCLUSION

Digital accumulation of toluidine blue- and/or c-Kit-positive dermal mast cells appears to be involved in the early stages of the pathological processes of SSc, especially in patients positive for anti-topoisomerase I antibody.

Suppression of streptozotocin-induced type-1 diabetes in mice by radon inhalation

We examined the protective effect of radon inhalation on streptozotocin (STZ)-induced type-1 diabetes in mice. Mice inhaled radon at concentrations of 1000, 2500, and 5500 Bq/m3 for 24 hours before STZ administration. STZ administration induced characteristics of type-1 diabetes such as hyperglycemia and hypoinsulinemia; however, radon inhalation at doses of 1000 and 5500 Bq/m3 significantly suppressed the elevation of blood glucose in diabetic mice. Serum insulin was significantly higher in mice pre-treated with radon at a dose of 1000 Bq/m3 than in mice treated with a sham. In addition, superoxide dismutase activities and total glutathione contents were significantly higher and lipid peroxide was significantly lower in mice pre-treated with radon at doses of 1000 and 5500 Bq/m3 than in mice treated with a sham. These results were consistent with the result that radon inhalation at 1000 and 5500 Bq/m3 suppressed hyperglycemia. These findings suggested that radon inhalation suppressed STZ-induced type-1 diabetes through the enhancement of antioxidative functions in the pancreas.

Preventive and curative effects of radon inhalation on chronic constriction injury-induced neuropathic pain in mice

BACKGROUND

Radon therapy is clinically useful for the treatment of pain-related diseases. However, there have been no studies regarding the effects of radon inhalation on neuropathic pain. In this study, we aimed to determine whether radon inhalation actually induced a remission of neuropathic pain and improved the quality of life.

METHODS

First, we investigated the antinociceptive effects of radon inhalation in the chronic constriction injury (CCI) model of neuropathic pain. We evaluated pain behaviour in mice before and after CCI surgery, using von Frey test. Pretreated mice received CCI surgery immediately after 24-h inhalation of radon at background (BG) concentration (c. 19 Bq/m(3) ), or at a concentration of 1000 or 2000 Bq/m(3) , and post-treated mice inhaled similar levels of radon 2 days after CCI surgery.

RESULTS

CCI surgery induced mechanical allodynia and hyperalgesia on a plantar surface of mice, as assessed using von Frey test, and 2000 Bq/m(3) radon inhalation alleviated hyperalgesic conditions 22-37% compared to BG level concentration. Concurrently, CCI surgery increased norepinephrine (NE), tumour necrosis factor-alpha (TNF-α) and nitric oxide (NO) concentrations in plasma, and leukocyte migration in paws. Furthermore, CCI-induced neuropathy reduced superoxide dismutase (SOD) activity. Treatment with radon inhalation, specifically at a concentration of 2000 Bq/m(3) , produced antinociceptive effects, i.e., lowered plasma TNF-α, NE and NO levels and restored SOD activity, as well as pain-related behaviour.

CONCLUSIONS

This study showed that inhalation of 2000 Bq/m(3) radon prevented and alleviated CCI-induced neuropathic pain in mice.

Radioactivity of 210Pb in Japanese cigarettes and radiation dose from smoking inhalation

It is well known that cigarette tobaccos contain naturally occurring radioactive nuclides such as (210)Pb and (210)Po. In many countries, the radioactivity of tobaccos has been measured to estimate the effective dose from smoking inhalation. The present study covered 24 cigarette brands including the top 20 of sales in Japan between April 2008 and March 2009. The activity concentrations of (210)Pb were measured by gamma-ray spectrometry, and then those of its progeny ((210)Po) were evaluated assuming the radioactive equilibrium between the two nuclides. Their concentrations were in the range of 2-14 mBq cigarette(-1) with an arithmetic mean of 8±3 mBq cigarette(-1). The annual committed effective doses were also calculated, based on the scenario that a smoker consumes 20 cigarettes a day. The average doses from (210)Pb and (210)Po inhalations were 22±9 and 68±27 μSv y(-1), respectively.

[Anti-rheumatic effect of JAK-inhibitors]

Treatment of rheumatoid arthritis (RA) has dramatically developed with the use of biologics targeting inflammatory cytokines. However, expense and parenteral use can cause issues in the initiation and continuation of the treatment. Therefore a new orally available anti-rheumatic drug has been long-awaited. Recently, small-molecule compounds targeting Janus kinase (JAK) has shown clinical efficacy similar to biologics in clinical trials for active RA. Among the JAK-inhibitors, new drug application for tofacitinib is concurrently under review in western and asian countries and is highly expected to become a new anti-rheumatic drug in the near future. In order to evaluate the mode of action, we utilized peripheral blood and synovium from RA patients. Proliferation and cytokine production of CD4+ T cell was prominently reduced and subsequently inhibited cartilage destruction by the synovium. Our result is in line with the inhibitory effect of tofacitinib on joint destruction in RA patients those who were treated with tofacitinib. Therefore, further clinical efficacy is expected in the in the long-term treatment with tofacitinib.

[Regulation of inflammation through JAK3-Stat6 pathway in dendritic cells]

Dendritic cells (DCs) is the cell that act as source of the immune response by exquisitely presenting antigens to acquired immunity such as the T cells. Janus kinase (JAK) is a tyrosine kinase that is activated immediately after the cytokine binds to its unique receptor expressed on the cell surface. Among the JAKs, expression of JAK3 is limited on haematopoietic cells and is indispensable for lymphocyte development and proliferation. We have demonstrated that JAK3-deficient DCs normally develop, uptake antigens, produce inflammatory cytokines and function as an antigen-presenting cell, although they over-produce IL-10. Among the transcription factors that are known to be activated by JAK3, we explored the phenotype of Stat6-deficient DCs which is a transcription factor specifically activated by JAK3. Interestingly, development, function and inflammatory cytokine production was normal with over-production of IL-10 which was in line with the JAK3-deficient DCs. IL-4 is well known to activate JAK3-Stat6 in the cytoplasm and has been reported to be produced in the synovial fluid of rheumatoid arthritis patients. Hence the suppression of IL-10 production by IL-4 can be considered as one of the inflammatory process of arthritis. Moreover, induction of IL-10 production by DCs can be one mechanism of action of the JAK inhibitor (tofacitinib) which have shown high efficiency on active rheumatoid arthritis in clinical trials.

[Involvement of Syk in pathology of systemic autoimmune disease]

Biological products have proven its high efficacy on autoimmune disease such as rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Meanwhile, small molecular drugs have attracted attention over the years because of its availability of oral administration and cost effectiveness. Spleen tyrosine kinase (Syk) is a 72 kDa protein tyrosine kinase widely expressed on cells that are involved in the immune system and inflammation such as B cells, T cells, macrophages and synovial fibroblast. Syk is involved in intracellular signaling of the multi-chain immune receptors, including B cell receptor (BCR), ζchain of T-cell receptor (TCR), FcR and integrins, which contains the immune-receptor tyrosine-based activation motif (ITAM). Recently, Syk inhibitor fostamatinib has exerted potent therapeutic efficacy against autoimmune and allergic diseases such as rheumatoid arthritis (RA), bronchial asthma and thrombocytopenic purpura (ITP). Moreover, Syk blockade prevented the development of skin and kidney lesions in lupus-prone mice, however the mechanism of action is unclear. We have revealed that Syk-mediated BCR-signaling is prerequisite for optimal induction of toll-like receptor (TLR)-9, thereby allowing efficient propagation of CD40- and TLR9- signaling in human B cells. These results indicate that inhibition of Syk have a potential to regulate B-cell mediated inflammatory diseases such as SLE. We here document the in vitro and in vivo effects of a Syk inhibitor for the treatment of autoimmune diseases, mainly in RA and SLE.

Relationship between pelagic larval duration and abundance of tropical fishes on temperate coasts of Japan

The influence of pelagic larval duration (PLD) and egg type dispersal capabilities of 35 demersal and pelagic-spawning tropical fish species is examined in relation to their abundance on the temperate coasts of Japan. The PLDs of pelagic spawners were significantly longer than those of demersal spawners, and a high occurrence of pelagic spawners on the temperate coasts suggests that these fishes are more easily transported to temperate coasts than demersal spawners. For demersal spawners, the common species on the temperate coasts had significantly longer PLDs than the rare species; this suggests that PLD is a major factor influencing the distribution patterns of tropical demersal spawners on temperate coasts. Moreover, a negative correlation between PLD and the abundance of some species of pelagic and demersal spawners suggests the presence of reproductively active fishes in northern subtropical and even in temperate waters.

Marked improvement of calcinosis in adult dermatomyositis with etidronate therapy

We report a 26-year-old woman with severe calcinosis associated with dermatomyositis. Although calcinosis of the skin or muscles is unusual in adults with dermatomyositis, this patient developed subcutaneous calcinosis with tenderness on the arms, axillary areas, shoulder areas, chest, abdomen, pelvis, and limbs. The calcinosis steadily increased and spread until joint motions were severely limited. Radiographic examination showed extensive soft-tissue calcification with a reticular pattern and severe osteoporosis. The patient was treated with oral etidronate (800 mg/day for 3 months every 6 months) to prevent calcification of the lesions. Three months later, the patient showed a dramatic improvement in symptoms with softening of the calcinosis, reduced pain, and marked increase in joint mobility. Radiographic examination showed marked decreases in the size of the calcified lesions compared to pre-treatment findings, and this effect persisted with a constant progressive efficacy for 3 years. The 3-year course of etidronate therapy also resulted in marked improvement of the severe osteoporosis and the patient was able to return to work and enjoy a normal life. We propose etidronate as a beneficial and effective therapy for calcinosis with osteoporosis.

The JAK inhibitor tofacitinib regulates synovitis through inhibition of interferon-γ and interleukin-17 production by human CD4+ T cells

OBJECTIVE

Tofacitinib (CP-690,550) is a novel JAK inhibitor that is currently in clinical trials for the treatment of rheumatoid arthritis (RA). The aim of this study was to examine the effects of tofacitinib in vitro and in vivo in RA, in order to elucidate the role of JAK in the disease process.

METHODS

CD4+ T cells, CD14+ monocytes, and synovial fibroblasts (SFs) were purified from the synovium and peripheral blood of patients with RA and were evaluated for the effect of tofacitinib on cytokine production and cell proliferation. For in vivo analysis, synovium and cartilage samples obtained from patients with RA were implanted in immunodeficient mice (SCID-HuRAg mice), and tofacitinib was administered via an osmotic minipump.

RESULTS

Tofacitinib treatment of CD4+ T cells originating from synovium and peripheral blood inhibited the production of interleukin-17 (IL-17) and interferon-γ (IFNγ) in a dose-dependent manner, affecting both proliferation and transcription, but had no effect on IL-6 and IL-8 production. Tofacitinib did not affect IL-6 and IL-8 production by RASFs and CD14+ monocytes. However, conditioned medium from CD4+ T cells cultured with tofacitinib inhibited IL-6 production by RASFs and IL-8 production by CD14+ monocytes. Treatment of SCID-HuRAg mice with tofacitinib decreased serum levels of human IL-6 and IL-8 and markedly suppressed invasion of synovial tissue into cartilage.

CONCLUSION

Tofacitinib directly suppressed the production of IL-17 and IFNγ and the proliferation of CD4+ T cells, resulting in inhibition of IL-6 production by RASFs and IL-8 production by CD14+ cells and decreased cartilage destruction. In CD4+ T cells, presumably Th1 and Th17 cells, JAK plays a crucial role in RA synovitis.

Dopamine induces IL-6-dependent IL-17 production via D1-like receptor on CD4 naive T cells and D1-like receptor antagonist SCH-23390 inhibits cartilage destruction in a human rheumatoid arthritis/SCID mouse chimera model

A major neurotransmitter dopamine transmits signals via five different seven-transmembrane G protein-coupled receptors termed D1-D5. Several studies have shown that dopamine not only mediates interactions into the nervous system, but can contribute to the modulation of immunity via receptors expressed on immune cells. We have previously shown an autocrine/paracrine release of dopamine by dendritic cells (DCs) during Ag presentation to naive CD4(+) T cells and found efficacious results of a D1-like receptor antagonist SCH-23390 in the experimental autoimmune encephalomyelitis mouse model of multiple sclerosis and in the NOD mouse model of type I diabetes, with inhibition of Th17 response. This study aimed to assess the role of dopaminergic signaling in Th17-mediated immune responses and in the pathogenesis of rheumatoid arthritis (RA). In human naive CD4(+) T cells, dopamine increased IL-6-dependent IL-17 production via D1-like receptors, in response to anti-CD3 plus anti-CD28 mAb. Furthermore, dopamine was localized with DCs in the synovial tissue of RA patients and significantly increased in RA synovial fluid. In the RA synovial/SCID mouse chimera model, although a selective D2-like receptor antagonist haloperidol significantly induced accumulation of IL-6(+) and IL-17(+) T cells with exacerbated cartilage destruction, SCH-23390 strongly suppressed these responses. Taken together, these findings indicate that dopamine released by DCs induces IL-6-Th17 axis and causes aggravation of synovial inflammation of RA, which is the first time, to our knowledge, that actual evidence has shown the pathological relevance of dopaminergic signaling with RA.

Phenotypic changes of lymphocytes in patients with systemic lupus erythematosus who are in longterm remission after B cell depletion therapy with rituximab

OBJECTIVE

Rituximab has recently emerged as a novel treatment strategy for systemic lupus erythematosus (SLE). We investigated longitudinally the differentiation and phenotypic changes of peripheral B cells and T cells in patients with SLE after rituximab treatment.

METHODS

Phenotypic changes on B cells and T cells in 10 patients with SLE treated with rituximab were analyzed before, 28 days after, and 2 years after rituximab treatment, and at relapse.

RESULTS

Rituximab rapidly depleted naive and memory B cells from the peripheral blood. In the patients with prolonged remission, the memory B cells remained depleted while naive B cells recovered within 3-9 months, and the expression levels of CD40 and CD80 remained downregulated for 2 years. There was also a decrease of memory T cells relative to naive T cells, and the expression of CD40L and inducible costimulator (ICOS) on CD4-positive T cells rapidly decreased and remained downregulated for 2 years. In 1 patient, an increase in the number of memory B cells with upregulation of CD40 and CD80 expression was noted just before relapse. In another patient with relapse, however, recovery of CD4-positive memory T cells with upregulation of ICOS expression was noted, with no change in the number of memory B cells.

CONCLUSION

Our results suggest that the phenotypic changes of peripheral B cells result in inhibition of T cell differentiation and activation mediated by B cells and thereby bring about longterm remission of SLE. Activated memory B cells or ICOS-positive CD4-positive memory T cells reappeared in association with relapse, probably reflecting the heterogeneity of SLE.

Efficacy of combination therapy of anti-TNF-α antibody infliximab and methotrexate in refractory entero-Behçet's disease

It is often difficult to manage refractory gastrointestinal tract complications of Behçet's disease (entero-BD) by conventional therapy. In this study, we assessed the short- and long-term efficacy and safety of the combination therapy of infliximab, an anti-tumor-necrosis-factor (TNF)-α antibody, and methotrexate in ten patients with refractory entero-BD refractory to conventional therapies. The short- (weeks) and long-term (by 2 years) effects of infliximab at 3-5 mg/kg body weight every 8 weeks on the clinical course and intestinal manifestations were assessed by abdominal computed tomography (CT) and colonoscopy. The primary endpoint was the rate of disappearance of ileocecal ulceration at 12 months of therapy. All patients showed improvement of gastrointestinal symptoms and disease-associated complications within 4 weeks. Furthermore, the rate of disappearance of ileocecal ulcerations was 50% (5/10 patients) at 6 months and 90% (9/10 patients) at 12 months, and, therefore 90% of patients were satisfied with the primary endpoint. Furthermore, corticosteroid dose was significantly reduced from 22.0 to 1.8 mg/day at 24 months. No severe adverse effects were observed during the 24 months of follow-up. We provide evidence for the rapid and excellent efficacy of infliximab in patients with refractory entero-BD and that the combination of infliximab and methotrexate brings about long-term alleviation of entero-BD and excellent tolerability.

Involvement of mast cells in systemic sclerosis

Systemic sclerosis is characterized by tissue fibrosis, obliterative microangiopathy and immune abnormalities. The etiology of SSc is largely unknown and is known to be resistant to existing corticosteroid and immunosuppressive drugs. Therefore, establishment of a treatment strategy especially for SSc patients with organ involvement is strongly desired. Mast cells are widely recognized as effector cells in allergic disorders and other IgE-mediated immune responses. However, recently, mast cells have become known to play a role in bridging innate immunity and adaptive immunity. Additionally, there is growing evidence of mast cell to be involved in pathogenesis of rheumatoid arthritis, and is expected as a novel therapeutic target. We describe here the role of mast cell in SSc pathology and suggest as a novel therapeutic target.

C5a promotes migration, proliferation, and vessel formation in endothelial cells

Objectives

The goal of this paper is to investigate the effects of activated complement C5a on vascular endothelium during vessel formation.

Methods

A human microvascular endothelial cell line (HMEC-1) derived from post-capillary venules in skin was used to measure DNA synthesis, proliferation and cell-cycle progression. In vitro ring-shaped formation by the cells was assessed by using type I collagen gel matrix and a cell-migration assay using the Chemotaxicell chamber. A Matrigel plug assay was performed to confirm the effect of C5a in vivo.

Results

C5a progressed the cell cycle of HMEC-1 into G2/M phases, and induced DNA synthesis and proliferation in a dose-dependent manner. C5a efficiently induced migration and ring-shaped structure formation both in vitro and in vivo. Furthermore, a C5a receptor antagonist (W-54011) suppressed all HMEC-1 activities including proliferation and migration.

Conclusions

Proliferation, migration, and ring-shaped formation by HMEC-1 cells was induced by C5a. The actions were efficiently inhibited by a specific antagonist against C5a. Our results implicated C5a in vessel formation and as a potent target for management of inflammatory diseases.

C5a promotes migration, proliferation, and vessel formation in endothelial cells

OBJECTIVES

The goal of this paper is to investigate the effects of activated complement C5a on vascular endothelium during vessel formation.

METHODS

A human microvascular endothelial cell line (HMEC-1) derived from post-capillary venules in skin was used to measure DNA synthesis, proliferation and cell-cycle progression. In vitro ring-shaped formation by the cells was assessed by using type I collagen gel matrix and a cell-migration assay using the Chemotaxicell chamber. A Matrigel plug assay was performed to confirm the effect of C5a in vivo.

RESULTS

C5a progressed the cell cycle of HMEC-1 into G2/M phases, and induced DNA synthesis and proliferation in a dose-dependent manner. C5a efficiently induced migration and ring-shaped structure formation both in vitro and in vivo. Furthermore, a C5a receptor antagonist (W-54011) suppressed all HMEC-1 activities including proliferation and migration.

CONCLUSIONS

Proliferation, migration, and ring-shaped formation by HMEC-1 cells was induced by C5a. The actions were efficiently inhibited by a specific antagonist against C5a. Our results implicated C5a in vessel formation and as a potent target for management of inflammatory diseases.

Tacrolimus, a calcineurin inhibitor, overcomes treatment unresponsiveness mediated by P-glycoprotein on lymphocytes in refractory rheumatoid arthritis

OBJECTIVE

Tacrolimus, a calcineurin inhibitor, is used for treatment of rheumatoid arthritis (RA). It also inhibits functions of P-glycoprotein, which is involved in drug resistance. We examined the mechanisms of early response to 2-week tacrolimus treatment in patients with RA.

METHODS

One hundred thirteen patients with refractory RA despite at least 3 antirheumatic agents, including methotrexate, were treated with tacrolimus (1.5-3 mg/day) and the response was assessed at 2 weeks. Expression of the multidrug resistance (MDR-1) gene and P-glycoprotein was assessed in peripheral blood mononuclear cells (PBMC) collected from 113 patients and 40 healthy subjects. The drug exclusion function by the P-glycoprotein was measured by the residual amount of intracellular tritium-labeled dexamethasone cell/medium ratio (C/M ratio).

RESULTS

The disease activity of enrolled patients was 5.8 +/- 1.2 (mean +/- SD) by DAS28 erythrocyte sedimentation rate. A good response to tacrolimus was noted at 2 weeks in 22 of 113 patients. At baseline, PBMC of patients with RA showed upregulated expression of MDR-1 gene and P-glycoprotein and low C/M ratio. The response to tacrolimus correlated with P-glycoprotein expression and C/M ratio. A significant improvement in C/M ratio was noted after 2 weeks of treatment. The C/M ratio correlated significantly with P-glycoprotein expression on CD4+ lymphocytes.

CONCLUSION

Early efficacy of tacrolimus treatment depended on its inhibitory effect on the drug exclusion function of P-glycoprotein, leading to restoration of intracellular therapeutic levels of corticosteroids and clinical improvement. Evaluation of P-glycoprotein expression on lymphocytes is potentially useful for predicting the response to RA treatment.

Involvement of fibroblast growth factor 18 in dedifferentiation of cultured human chondrocytes

OBJECTIVE

Chondrocytes inevitably decrease production of cartilaginous matrices during long-term cultures with repeated passaging; this is termed dedifferentiation. To learn more concerning prevention of dedifferentiation, we have focused here on the fibroblast growth factor (FGF) family that influences chondrocyte proliferation or differentiation.

MATERIALS AND METHODS

We have compared gene expression between differentiated cells in passage 3 (P3) and dedifferentiated ones in P8 of human cultured chondrocytes. We also performed ligand administration of the responsive factor or its gene silencing, using small interfering RNA (siRNA).

RESULTS

FGFs 1, 5, 10, 13 and 18 were higher at P8 compared to P3, while FGFs 9 and 14 were lower. Especially, FGF18 showed a 10-fold increase by P8. Ligand administration of FGF18 in the P3 cells, or its gene silencing using siRNA in the P8 cells, revealed dose-dependent increase and decrease respectively in type II collagen/type I collagen ratio. Exogenous FGF18 also upregulated expression of transforming growth factor beta (TGF-beta), the anabolic factor of chondrocytes, in P3 chondrocytes, but P8 cells maintained a low level of TGF-beta expression, suggesting a decrease in responsiveness of TGF-beta to FGF18 stimulation in the dedifferentiated chondrocytes.

CONCLUSION

FGF18 seems to play a role in maintenance of chondrocyte properties, although its expression was rather high in dedifferentiated chondrocytes. Upregulation of FGF18 in dedifferentiated chondrocytes implied that it may be a marker of dedifferentiation.

Jak inhibitor ; possibility and mechanism as a new disease modifying anti-rheumatic drug

Treatment of rheumatoid arthritis (RA) has developed dramatically by the appearance of biologics. However the development of a new anti-rheumatic drug is necessary because of its issue on route of administration and expense. Recently, inhibitors targeting tyrosine kinase known as Janus kinase (Jak) has shown prominent effect on RA. Jak family is comprised by Jak1, Jak2, Jak3 and Tyk2 which is necessary for signal transduction for inflammatory cytokines. INCB18424 targeting Jak1/2 and CP690,550 targeting Jak3 has been developed and is now on phase II clinical study for RA. Results from those clinical studies have proven that these inhibitors can be effective as biologics with few side effects. However, it has been reported that inhibitors are less specific than it has been expect and that non-specificity can be important for its effect. Therefore, we think that the mechanism of inhibitors cannot be explained by its inhibition of a single kinase. Herein, we describe IL-10 overproduction by Jak3 and Stat6 deficient dendritic cell. We speculate that this is one possible mechanism of action for CP690,550 although as for its non-specificity we need further investigation to predict not only its effect but also its side effect in a long term administration.