Metformin is widely used to suppress certain functions of the cells found in diseases including diabetes and obesity. In this study, the effects of metformin on downregulating IL-17-producing T (Th17) cells, activating and upregulating regulatory T (Treg) cells, suppressing osteoclastogenesis, and clinically scoring collagen-induced arthritis (CIA) were investigated. To evaluate the effect of metformin on CIA, mice were orally fed with either metformin or saline as control three times a week for nine weeks. Histological analysis of the joints was performed using immunohistochemistry and Th17 cells and Treg cells of the spleen tissue were examined by confocal microscopy staining. Metformin mitigated the severity of CIA, reduced serum immunoglobulin concentrations, and reciprocally regulated Th17/Treg axis. Also, metformin treatment of normal cells cultured in Th17 conditions decreased the number of Th17 cells and increased the number of Treg cells. Metformin decreased gene expression and osteoclastogenic activity in CIA and normal mice. These results indicate that metformin had immunomodulatory actions influencing anti-inflammatory action on CIA through the inhibition of Th17 cell differentiation and the upregulation of Treg cell differentiation along with the suppression of osteoclast differentiation. Our results suggest that metformin may be a potential therapeutic for rheumatoid arthritis.
Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic joint inflammation. Red ginseng is a steamed and dried Panax ginseng C.A. Meyer, which has been used as alternative medicine for thousands of years. This study was undertaken to investigate the effects of red ginseng extracts (RGE) on autoimmune arthritis in mice and humans and to delineate the underlying mechanism. RGE was orally administered three times a week to mice with arthritis. Oral administration of RGE markedly ameliorated clinical arthritis score and histologically assessed joint inflammation in mice with CIA. A significant reduction in STAT3 phosphorylation and a decrease in the number of Th17 cells were observed with RGE treatment. There was also a marked reduction in RANKL-induced osteoclastogenesis with treatment of RGE. The inhibitory effect of RGE on Th17 differentiation and osteoclastogenesis observed in mice was also confirmed in the subsequent experiments performed using human peripheral blood mononuclear cells. Our findings provide the first evidence that RGE can regulate Th17 and reciprocally promote Treg cells by inhibiting the phosphorylation of STAT3. Therefore, RGE can ameliorate arthritis in mice with CIA by targeting pathogenic Th17 and osteoclast differentiation, suggesting a novel therapy for treatment of RA.
This study was undertaken to identify the intracellular signaling pathway involved in induction of macrophage migration inhibitory factor (MIF) in human rheumatoid arthritis (RA) synovial fibroblasts.
Human RA synovial fibroblasts were treated with concanavalin A (ConA), various cytokines, and inhibitors of signal transduction molecules. The production of MIF by synovial fibroblasts was measured in culture supernatants by ELISA. The expression of MIF mRNA was determined using reverse transcriptase polymerase chain reaction (RT-PCR) and real-time PCR. Phosphorylation of p38 mitogen-activated protein (MAP) kinase in synovial fibroblasts was confirmed using Western blotting. The expression of MIF and p38 MAP kinase in RA synovium was determined using dual immunohistochemistry.
The production of MIF by RA synovial fibroblasts increased in a dose-dependent manner after ConA stimulation. MIF was also induced by interferon-γ, CD40 ligand, interleukin-15, interleukin-1β, tumor necrosis factor-α, and transforming growth factor-β. The production of MIF by RA synovial fibroblasts was significantly reduced after inhibition of p38 MAP kinase. The expression of MIF and p38 MAP kinase was upregulated in the RA synovium compared with the osteoarthritis synovium.
These results suggest that MIF production was induced through a p38 MAP-kinase-dependent pathway in RA synovial fibroblasts.
Macrophage, migration-inhibitory factors; Arthritis rheumatoid; Synovial fibroblast; p38 mitogen-activated protein kinases
Epigallocatechin-3-gallate (EGCG) is a green tea polyphenol exerting potent anti-oxidant and anti-inflammatory effects by inhibiting signaling and gene expression. The objective of the study was to evaluate the effect of EGCG on interleukin (IL)-1 receptor antagonist knockout (IL-1RaKO) autoimmune arthritis models. IL-1RaKO arthritis models were injected intraperitoneally with EGCG three times per week after the first immunization. EGCG decreased the arthritis index and showed protective effects against joint destruction in the IL-1RaKO arthritis models. The expression of pro-inflammatory cytokines, oxidative stress proteins, and p-STAT3 (Y705) and p-STAT3 (S727), mTOR and HIF-1α were significantly lower in mice treated with EGCG. EGCG reduced osteoclast markers in vivo and in vitro along with anti-osteoclastic activity was observed in EGCG-treated IL-1RaKO mice. The proportion of Foxp3+ Treg cells increased in the spleens of mice treated with EGCG, whereas the proportion of Th17 cells reduced. In vitro, p-STAT3 (Y705) and p-STAT3 (S727), HIF1α and glycolytic pathway molecules were decreased by EGCG. EGCG suppressed the activation of mTOR and subsequently HIF-1α, which is considered as a metabolic check point of Th17/Treg differentiation supporting the therapeutic potential of EGCG in autoimmune arthritis.
Osteoarthritis (OA) is a degenerative joint disease characterized by a progressive loss of cartilage. And, increased oxidative stress plays a relevant role in the pathogenesis of OA. Ursodeoxycholic acid (UDCA) is a used drug for liver diseases known for its free radical-scavenging property. The objectives of this study were to investigate the in vivo effects of UDCA on pain severity and cartilage degeneration using an experimental OA model and to explore its mode of actions. OA was induced in rats by intra-articular injection of monosodium iodoacetate (MIA) to the knee. Oral administration UDCA was initiated on the day of MIA injection. Limb nociception was assessed by measuring the paw withdrawal latency and threshold. Samples were analyzed macroscopically and histologically. Immunohistochemistry was used to investigate the expression of interleukin-1β (IL-1β), IL-6, nitrotyrosine and inducible nitric oxide synthase (iNOS) in knee joints. UDCA showed an antinociceptive property and attenuated cartilage degeneration. OA rats given oral UDCA significantly exhibited a decreased number of osteoclasts in subchondral bone legion compared with the vehicle-treated OA group. UDCA reduced the expression of IL-1β, IL-6, nitrotyrosine and iNOS in articular cartilage. UDCA treatment significantly attenuated the mRNA expression of matrix metalloproteinase-3 (MMP-3), -13, and ADAMTS5 in IL-1β-stimulated human OA chondrocytes. These results show the inhibitory effects of UDCA on pain production and cartilage degeneration in experimentally induced OA. The chondroprotective properties of UDCA were achieved by suppressing oxidative damage and inhibiting catabolic factors that are implicated in the pathogenesis of cartilage damage in OA.
Ursodeoxycholic acid (UDCA); Monosodium iodoacetate (MIA); Osteoarthritis; Oxidative stress
T follicular helper (Tfh) cells are specialized providers of cognate B cell help, which is important in promoting the induction of high-affinity antibody production in germinal centers (GCs). Interleukin-6 (IL-6) and IL-21 have been known to play important roles in Tfh cell differentiation. Here, we demonstrate that IL-7 plays a pivotal role in Tfh generation and GC formation in vivo, as treatment with anti-IL-7 neutralizing antibody markedly impaired the development of Tfh cells and IgG responses. Moreover, codelivery of mouse Fc-fused IL-7 (IL-7-mFc) with a vaccine enhanced the generation of GC B cells as well as Tfh cells but not other lineages of T helper cells, including Th1, Th2, and Th17 cells. Interestingly, a 6-fold-lower dose of an influenza virus vaccine codelivered with Fc-fused IL-7 induced higher antigen-specific and cross-reactive IgG titers than the vaccine alone in both mice and monkeys and led to markedly enhanced protection against heterologous influenza virus challenge in mice. Enhanced generation of Tfh cells by IL-7-mFc treatment was not significantly affected by the neutralization of IL-6 and IL-21, indicating an independent role of IL-7 on Tfh differentiation. Thus, IL-7 holds promise as a critical cytokine for selectively inducing Tfh cell generation and enhancing protective IgG responses.
IMPORTANCE Here, we demonstrate for the first time that codelivery of Fc-fused IL-7 significantly increased influenza virus vaccine-induced antibody responses, accompanied by robust expansion of Tfh cells and GC B cells as well as enhanced GC formation. Furthermore, IL-7-mFc induced earlier and cross-reactive IgG responses, leading to striking protection against heterologous influenza virus challenge. These results suggest that Fc-fused IL-7 could be used for inducing strong and cross-protective humoral immunity against highly mutable viruses, such as HIV and hepatitis C virus, as well as influenza viruses.
Ursolic acid (UA) is a pentacyclic triterpenoid found in most plant species, which has been shown anti-inflammatory and anti-oxidative activities. In this study, we examined the effects of UA on collagen-induced arthritis (CIA) in mice, and to identify the mechanisms underlying the effects.
CIA was induced in mice. Two weeks later, the mice were treated with UA (150 mg/kg, ip, 3 times per week) for 4 weeks. The expression of cytokines and oxidative stress markers in joint tissues was measured with immunohistochemistry. The numbers of CD4+IL-17+, CD4+CD25+Foxp3+ and pSTAT3 cells in spleens were determined using confocal immunostaining or flowcytometric analyses. Serum antibody levels and B cell-associated marker mRNAs were analyzed with ELISAs and qRT-PCR, respectively. CD4+ T cells and CD19+ B cells were purified from mice spleens for in vitro studies.
UA treatment significantly reduced the incidence and severity of CIA-induced arthritis, accompanied by decreased expression of proinflammatory cytokines (TNF-α, IL-1β, IL-6, IL-21 and IL-17) and oxidative stress markers (nitrotyrosine and iNOS) in arthritic joints. In CIA mice, UA treatment significantly decreased the number of Th17 cells, while increased the number of Treg cells in the spleens, which was consistent with decreased expression of pSTAT3, along with IL-17 and RORγt in the splenocytes. In addition, UA treatment significantly reduced the serum CII-specific IgG levels in CIA mice. The inhibitory effects of UA on Th17 cells were confirmed in an in vitro model of Th17 differentiation. Furthermore, UA dose-dependently suppressed the expression of B cell-associated markers Bcl-6, Blimp1 and AID mRNAs in purified CD19+ B cells pretreated with IL-21 or LPS in vitro.
UA treatment significantly ameliorates CIA in mice via suppression of Th17 and differentiation. By targeting pathogenic Th17 cells and autoantibody production, UA may be useful for the treatment of autoimmune arthritis and other Th17-related diseases.
ursolic acid; rheumatoid arthritis; collagen-induced arthritis; Th17 cell; regulatory T cell; B cell; spleen; proinflammatory cytokine; STAT3
Interleukin-1β (IL-1β) is a potent proinflammatory and immunoregulatory cytokine playing an important role in the progression of rheumatoid arthritis (RA). However, the signaling network of IL-1β in synoviocytes from RA patients is still poorly understood. Here, we show for the first time that phospholipase D1 (PLD1), but not PLD2, is selectively upregulated in IL-1β-stimulated synoviocytes, as well as synovium, from RA patients. IL-1β enhanced the binding of NF-κB and ATF-2 to the PLD1 promoter, thereby enhancing PLD1 expression. PLD1 inhibition abolished the IL-1β-induced expression of proinflammatory mediators and angiogenic factors by suppressing the binding of NF-κB or hypoxia-inducible factor 1α to the promoter of its target genes, as well as IL-1β-induced proliferation or migration. However, suppression of PLD1 activity promoted cell cycle arrest via transactivation of FoxO3a. Furthermore, PLD1 inhibitor significantly suppressed joint inflammation and destruction in IL-1 receptor antagonist-deficient (IL-1Ra−/−) mice, a model of spontaneous arthritis. Taken together, these results suggest that the abnormal upregulation of PLD1 may contribute to the pathogenesis of IL-1β-induced chronic arthritis and that a selective PLD1 inhibitor might provide a potential therapeutic molecule for the treatment of chronic inflammatory autoimmune disorders.
Grape seed proanthocyanidin extract (GSPE) is a natural flavonoid that exerts anti-inflammatory properties. Obesity is an inflammatory condition and inflammatory cells and their secretion of pro-inflammatory molecules contribute to the pathogenesis of obesity. Rheumatoid arthritis (RA) is a chronic autoimmune disease that is characterized by inflammation of joints lined by synovium. Previously, we demonstrated that obesity augmented arthritis severity in collagen induced arthritis (CIA), a murine model of human RA. Here, we investigated whether oral administration of GSPE showed antiobesity and anti-arthritic effects in high-fat diet-induced obese (DIO) mice and in obese CIA mice, respectively. The pathophysiologic mechanisms by which GSPE attenuates weight gain and arthritis severity in vivo were also investigated. In DIO mice, GSPE administration significantly inhibited weight gain, reduced fat infiltration in liver and improved serum lipid profiles. The antiobesity effect of GSPE was associated with increased populations of regulatory T (Treg) cells and those of decreased Th17 cells. Decrease of Th17 cells was associated with significant inhibition of their key transcriptional factors, pSTAT3Tyr705 and pSTAT3Ser727. On the contrary, GSPE-induced Treg induction was associated with enhanced pSTAT5 expression. To identify the anti-arthritis effects of GSPE, GSPE was given orally for 7 weeks after type II collagen immunization. GSPE treatment significantly attenuated the development of autoimmune arthritis in obese CIA model. In line with DIO mice, GSPE administration decreased Th17 cells and reciprocally increased Treg cells by regulating STAT proteins in autoimmune arthritis model. The expressions of pro-inflammatory cytokines and nitrotyrosine in synovium were significantly inhibited by GSPE treatment. Taken together, GSPE functions as a reciprocal regulator of T cell differentiation – suppression of Th17 cells and induction of Tregs in both DIO and obese CIA mice. GSPE may act as a therapeutic agent to treat immunologic diseases related with enhanced STAT3 activity such as metabolic disorders and autoimmune diseases.
Interleukin (IL)-27 is a novel cytokine of the IL-6/IL-12 family that has been reported to be involved in the pathogenesis of autoimmune diseases and has a pivotal role as both a pro- and anti-inflammatory cytokine. We investigated the in vivo effects of IL-27 on arthritis severity in a murine collagen-induced arthritis (CIA) model and its mechanism of action regarding control of regulatory T (Tregs) and IL-17-producing T helper 17 (Th17) cells. IL-27-Fc-treated CIA mice showed a lower severity of arthritis. IL-17 expression in the spleens was significantly decreased in IL-27-Fc-treated CIA mice compared with that in the CIA model. The Th17 population was decreased in the spleens of IL-27-Fc-treated CIA mice, whereas the CD4+CD25+Foxp3+ Treg population increased. In vitro studies revealed that IL-27 inhibited IL-17 production in murine CD4+ T cells, and the effect was associated with retinoic acid-related orphan receptor γT and signal transducer and activator of transcription 3 inhibition. In contrast, fluorescein isothiocyanate-labeled forkhead box P3 (Foxp3) and IL-10 were profoundly augmented by IL-27 treatment. Regarding the suppressive capacity of Treg cells, the proportions of CTLA-4+ (cytotoxic T-lymphocyte antigen 4), PD-1+ (programmed cell death protein 1) and GITR+ (glucocorticoid-induced tumor necrosis factor receptor) Tregs increased in the spleens of IL-27-Fc-treated CIA mice. Furthermore, in vitro differentiated Treg cells with IL-27 exerted a more suppressive capacity on T-cell proliferation. We found that IL-27 acts as a reciprocal regulator of the Th17 and Treg populations in CD4+ cells isolated from healthy human peripheral blood mononuclear cells (PBMCs), as well as from humans with rheumatoid arthritis (RA) PBMCs. Our study suggests that IL-27 has the potential to ameliorate overwhelming inflammation in patients with RA through a reciprocal regulation of Th17 and Treg cells.
collagen-induced arthritis; interleukin-27; interleukin-17-producing T cells; regulatory T cells; rheumatoid arthritis
Mesenchymal stromal cells (MSCs) are seen as an ideal source of cells to induce graft acceptance; however, some reports have shown that MSCs can be immunogenic rather than immunosuppressive. We speculate that the immunomodulatory effects of regulatory T cells (Tregs) can aid the maintenance of immunoregulatory functions of MSCs, and that a combinatorial approach to cell therapy can have synergistic immunomodulatory effects on allograft rejection. After preconditioning with Fludarabine, followed by total body irradiation and anti-asialo-GM-1(ASGM-1), tail skin grafts from C57BL/6 (H-2kb) mice were grafted onto the lateral thoracic wall of BALB/c (H-2kd) mice. Group A mice (control group, n = 9) did not receive any further treatment after preconditioning, whereas groups B and C (n = 9) received cell therapy with MSCs or Tregs, respectively, on days −1, +6 and +13 relative to the skin transplantation. Group D (n = 10) received cell therapy with MSCs and Tregs on days −1, +6 and +13. Cell suspensions were obtained from the spleens of five randomly chosen mice from each group on day +7, and the immunomodulatory effects of the cell therapy were evaluated by flow cytometry and real-time PCR. Our results show that allograft survival was significantly longer in group D compared to the control group (group A). Flow cytometric analysis and real-time PCR for splenocytes revealed that the Th2 subpopulation in group D increased significantly compared to the group B. Also, the expression of Foxp3 and STAT 5 increased significantly in group D compared to the conventional cell therapy groups (B and C). Taken together, these data suggest that a combined cell therapy approach with MSCs and Tregs has a synergistic effect on immunoregulatory function in vivo, and might provide a novel strategy for improving survival in allograft transplantation.
To investigate the effect of CoenzymeQ10 (CoQ10) on pain severity and cartilage degeneration in an experimental model of rat osteoarthritis (OA).
Materials and Methods
OA was induced in rats by intra-articular injection of monosodium iodoacetate (MIA) to the knee. Oral administration of CoQ10 was initiated on day 4 after MIA injection. Pain severity was assessed by measuring secondary tactile allodynia using the von Frey assessment test. The degree of cartilage degradation was determined by measuring cartilage thickness and the amount of proteoglycan. The mankin scoring system was also used. Expressions of matrix metalloproteinase-13 (MMP-13), interleukin-1β (IL-1β), IL-6, IL-15, inducible nitric oxide synthase (iNOS), nitrotyrosine and receptor for advanced glycation end products (RAGE) were analyzed using immunohistochemistry.
Treatment with CoQ10 demonstrated an antinociceptive effect in the OA animal model. The reduction in secondary tactile allodynia was shown by an increased pain withdrawal latency and pain withdrawal threshold. CoQ10 also attenuated cartilage degeneration in the osteoarthritic joints. MMP-13, IL-1β, IL-6, IL-15, iNOS, nitrotyrosine and RAGE expressions were upregulated in OA joints and significantly reduced with CoQ10 treatment.
CoQ10 exerts a therapeutic effect on OA via pain suppression and cartilage degeneration by inhibiting inflammatory mediators, which play a vital role in OA pathogenesis.
In this study we examined the in vivo and in vitro effects and mechanisms of action of curcumin on the development of acute graft-versus-host disease (GVHD) using a murine model.
Mixed lymphocyte reactions were used to determine the in vitro effects of curcumin. Treatment with curcumin attenuated alloreactive T cell proliferation and inhibited the production of interferon (IFN)-γ and interleukin (IL)-17. In a murine acute GVHD model, transplantation of curcumin-treated allogeneic splenocytes into irradiated recipient mice significantly reduced the clinical severity scores of acute GVHD manifested in the liver, skin, colon and lung as compared with animals receiving vehicle-treated splenocytes. c-Fos and c-Jun expression levels in the skin and intestine, which are major target organs, were analyzed using immunohistochemical staining. Expression of both proteins was reduced in epithelial tissues of skin and intestine from curcumin-treated GVHD animals. The IFN-γ-expressing CD4+ splenocytes and IFN-γ-expressing lymph node cells were dramatically decreased in curcumin-treated mice. In contrast, CD4+Foxp3+ splenocytes were increased in the curcumin-treated acute GVHD animals. Flow cytometric analysis revealed that animals transplanted with curcumin-treated allogeneic splenocytes showed increased populations of CD4+ regulatory T cells (Tregs) as well as CD8+ Treg cells, compared to animals administered vehicle-treated splenocytes. Curcumin-treated acute GVHD animals could have a change in B cell subpopulations.
In the present study, we investigated the efficacy and mechanism of action of curcumin treatment against acute GVHD. The acute GVHD mice administered with curcumin-treated splenocytes showed significantly reduced severity of acute GVHD. Curcumin exerted in vivo preventive effects on acute GVHD by reciprocal regulation of T helper 1 (Th1) and Treg (both CD4+ and CD8+ Treg) cell lineages as well as B cell homeostasis.
To investigate the gastroprotective effects of grape seed proanthocyanidin extracts (GSPEs) against nonsteroid anti-inflammatory drug (NSAID)-induced gastric mucosal injury in rats.
Sprague-Dawley rats were randomly allocated to the normal control, indomethacin, low-dose GSPE, high-dose GSPE and misoprostol groups. All groups except the normal control group received pretreatment drugs for 6 consecutive days. On the 5th and 6th day, indomethacin was administered orally to all groups except for normal control group. The microscopic features of injury were analyzed. The levels of gastric mucosal glutathione, gastric mucosal prostaglandin E2 (PGE2), and proinflammatory cytokines were investigated.
The total areas of ulceration in the GSPE and misoprostol groups were significantly decreased compared with the indomethacin group (p<0.05). However, a difference in ulcer formation among the drug treatment groups was not observed. Meanwhile, the glutathione levels in the high-dose GSPE group were higher than those of both the indomethacin and misoprostol groups (p<0.05) and were similar to those of the normal control group. Additionally, there was no difference among the groups in the levels of gastric mucosal PGE2 and proinflammatory cytokines.
High-dose GSPE has a strong protective effect against NSAID-induced gastric mucosal injury, which may be associated with the antioxidant effects of GSPE.
Nonsteroid anti-inflammatory drug; Grape seed proanthocyanidins; Gastropathy; Antioxidants
C57BL/6 mice are known to be resistant to the development of collagen-induced arthritis (CIA). However, they show a severe arthritic phenotype when the Ifng gene is deleted. Although it has been proposed that IFN-γ suppresses inflammation in CIA via suppressing Th17 which is involved in the pathogenesis of CIA, the exact molecular mechanism of the Th17 regulation by IFN-γ is poorly understood. This study was conducted to 1) clarify that arthritogenic condition of IFN-γ knockout (KO) mice is dependent on the disinhibition of Th17 and 2) demonstrate that IFN-γ-induced indoleamine2,3dioxgenase (IDO) is engaged in the regulation of Th17. The results showed that the IFN-γ KO mice displayed increased levels of IL-17 producing T cells and the exacerbation of arthritis. Also, production of IL-17 by the splenocytes of the IFN-γ KO mice was increased when cultured with type II collagen. When Il17 was deleted from the IFN-γ KO mice, only mild arthritis developed without any progression of the arthritis score. The proportion of CD44highCD62Llow memory-like T cells were elevated in the spleen, draining lymph node and mesenteric lymph node of IFN-γ KO CIA mice. Meanwhile, CD44lowCD62Lhigh naïve T cells were increased in IFN-γ and IL-17 double KO CIA mice. When Th17 polarized CD4+ T cells of IFN-γ KO mice were co-cultured with their own antigen presenting cells (APCs), a greater increase in IL-17 production was observed than in co-culture of the cells from wild type mice. In contrast, when APCs from IFN-γ KO mice were pretreated with IFN-γ, there was a significant reduction in IL-17 in the co-culture system. Of note, pretreatment of 1-methyl-DL- tryptophan, a specific inhibitor of IDO, abolished the inhibitory effects of IFN-γ. Given that IFN-γ is a potent inducer of IDO in APCs, these results suggest that IDO is involved in the regulation of IL-17 by IFN-γ.
Fibroblast-like synoviocytes (FLSs) are a major cell population of the pannus that invades adjacent cartilage and bone in rheumatoid arthritis (RA). The study was undertaken to determine the effect of interleukin-17 (IL-17) on the survival and/or proliferation of FLSs from RA patients and to investigate whether signal tranducer and activator of transcription 3 (STAT3) is implicated in this process.
Bcl-2 and Bax expression in FLSs was determined using the real-time PCR and western blot analysis. The expression of Bcl-2 and phosphoSTAT3 in synovial tissues was investigated by confocal microscope. Apoptosis of FLSs was detected by Annexin V/propidium iodide staining and/or phase contrast microscopy. The proliferation of FLSs was determined by CCK-8 ELISA assay.
The pro-apoptotic Bax is decreased and anti-apoptotic Bcl-2 is increased in FLSs from RA patients compared with those from patients with osteoarthritis (OA). IL-17 upregulated the expression of Bcl-2 in FLSs from RA patients, but not in FLSs from OA patients. STAT3 was found to mediate IL-17-induced Bcl-2 upregulation in FLSs from RA patients. Additionally, IL-17 promoted the survival and proliferation of FLSs from RA patients. Most importantly, treatment with STAT3 inhibitor reversed the protective effect of IL-17 on FLSs apoptosis induced by sodium nitroprusside (SNP).
Our data demonstrate that STAT3 is critical in IL-17-induced survival of FLS from RA patients. Therefore, therapeutic strategies that target the IL-17/STAT3 pathway might be strong candidates for RA treatment modalities.
Chronic autoimmune inflammation, which is commonly observed in rheumatoid arthritis (RA), disrupts the delicate balance between bone resorption and formation causing thedestruction of the bone and joints. We undertook this study to verify the effects of natural grape-seed proanthocyanidin extract (GSPE), an antioxidant, on chronic inflammation and bone destruction. GSPE administration ameliorated the arthritic symptoms of collagen-induced arthritis (CIA), which are representative of cartilage and bone destruction. GSPE treatment reduced the formation of tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells and osteoclast activity and increased differentiation of mature osteoblasts. Receptor activator of NFκB ligand expression in fibroblasts from RA patients was abrogated with GSPE treatment. GSPE blocked human peripheral blood mononuclear cell-derived osteoclastogenesis and acted as an antioxidant. GSPE improved the arthritic manifestations of CIA mice by simultaneously suppressing osteoclast differentiation and promoting osteoblast differentiation. Our results suggest that GSPE may be beneficial for the treatment of inflammation-associated bone destruction.
IL-17-producing CD4+ T cells (Th17) play important functions in autoimmune diseases and allograft rejection of solid organs. We examined the effects of IL 17 and its mechanism of action on arthritis in a murine collagen-induced arthritis (CIA) model using bone marrow transplantation (BMT) system. DBA/1J mice were administered a lethal radiation dose and then rescued with bone marrow derived from either wild-type (WT) or IL-17-/- mice on C57BL/6 background mice. CIA was induced after the bone marrow transplant, and disease progression was characterized. DBA/1J mice with CIA that received IL-17-/- donor bone marrow showed potently inhibited development and severity of clinical arthritis as compared with CIA mice that received WT bone marrow. Reduced secretion of the pro-inflammatory cytokines tumor necrosis factor-α, IL-1β, and IL-6, and collagen-specific T cell responses were observed in mice that received IL-17-/- bone marrow. IL-17 blockade also inhibited effector T cell proliferation by reciprocally regulating the Treg/Th17 ratio. IL-17 blockade prevented joint destruction in mice with CIA. These findings suggest that CIA with BMT is a viable method of immunological manipulation and that IL-17 deficiency suppresses severe joint destruction and inflammation in CIA mice. There may be clinical benefits in blocking IL-17 and BMT in the treatment of rheumatoid arthritis.
arthritis, experimental; bone marrow transplantation; interleukin-17; Th17 cells; T-lymphocytes, regulatory; transplantation, homologous
Interleukin (IL)-32 and IL-17 play critical roles in pro-inflammatory responses and are highly expressed in the synovium of patients with rheumatoid arthritis (RA). We investigated the relations between these two cytokines (IL-17 and IL-32) for their ability to induce each other and to stimulate osteoclasts in RA fibroblast-like synoviocytes (FLSs) and T cells.
FLSs were isolated through surgical synovectomy obtained from patients with RA or osteoarthritis (OA). Real-time PCR were performed to evaluate the expression of IL-32, IL-17 and osteoclast-related genes. Immunohistochemical staining and tartrate-resistant acid phosphatase (TRAP) staining were performed to determine the distribution of inflammatory cytokines and the presence of osteoclastogenesis.
IL-17 induced the expression of IL-32 in the FLSs from RA patients, as assessed by microarray. IL-32 production was increased by IL-17. IL-32 in the FLSs from RA patients induced the production of IL-17 in CD4+ T cells. IL-32 and IL-17 were colocalized near TRAP-positive areas in joint specimens. IL-17 and IL-32 synergistically induced the differentiation of osteoclasts, as demonstrated by the expression of osteoclast-related genes. IL-32 and IL-17 also could induce resorption by osteoclasts in a RANKL-dependent manner.
IL-17 affected the expression of IL-32 in FLSs of RA patients and IL-32 induced the production of IL-17 in CD4+ T cells. Both IL-17 and IL-32 cytokines can reciprocally influence each other's production and amplify the function of osteoclastogenesis in the in RA synovium. Separately, IL-17 and IL-32 each stimulated osteoclastogenesis without RANKL. Together, the two cytokines synergistically amplified the differentiation of osteoclasts, independent of RANKL stimulation.
Most of the previous studies on immune dysregulation in end-stage renal disease (ESRD) have focused on T cell immunity. We investigated B cell subpopulations in ESRD patients and the effect of hemodialysis (HD) on B cell-associated immune profiles in these patients. Forty-four ESRD [maintenance HD patients (n = 27) and pre-dialysis patients (n = 17)] and 27 healthy volunteers were included in this study. We determined the percentage of B cell subtypes, such as mature and immature B cells, memory B cells, and interleukin (IL)-10+ cells, as well as B cell-producing cytokines (IL-10, IL-4 and IL-21) by florescent activated cell sorting (FACS). B cell-associated gene expression was examined using real-time PCR and B cell producing cytokines (IL-10, IL-4 and IL-21) were determined using an enzyme-linked immunosorbent assay (ELISA). The percentage of total B cells and mature B cells did not differ significantly among the three groups. The percentages of memory B cells were significantly higher in the pre-dialysis group than in the HD group (P < 0.01), but the percentage of immature B cells was significantly lower in the pre-dialysis group than in the other groups. The percentages of IL-10-expressing cells that were CD19+ or immature B cells did not differ significantly (P > 0.05) between the two subgroups within the ESRD group, but the serum IL-10 concentration was significantly lower in the pre-dialysis group (P < 0.01). The results of this study demonstrate significantly altered B cell-associated immunity. Specifically, an imbalance of immature and memory B cells in ESRD patients was observed, with this finding predominating in pre-dialysis patients.
B-lymphocyte subsets; kidney failure, chronic; precursor cells, B-lymphoid; renal dialysis
White fat cells secrete adipokines that induce inflammation and obesity has been reported to be characterized by high serum levels of inflammatory cytokines such as IL-6 and TNF-α. Rheumatoid arthritis (RA) is a prototype of inflammatory arthritis, but the relationship between RA and obesity is controversial. We made an obese inflammatory arthritis model: obese collagen-induced arthritis (CIA). C57BL/6 mice were fed a 60-kcal high fat diet (HFD) from the age of 4 weeks and they were immunized twice with type II collagen (CII). After immunization, the obese CIA mice showed higher arthritis index scores and histology scores and a more increased incidence of developing arthritis than did the lean CIA mice. After treatment with CII, mixed lymphocyte reaction also showed CII-specific response more intensely in the obese CIA mice than lean CIA. The anti-CII IgG and anti-CII IgG2a levels in the sera of the obese CIA mice were higher than those of the lean CIA mice. The number of Th17 cells was higher and the IL-17 mRNA expression of the splenocytes in the obese CIA mice was higher than that of the lean CIA mice. Obese CIA mice also showed high IL-17 expression on synovium in immunohistochemistry. Although obesity may not play a pathogenic role in initiating arthritis, it could play an important role in amplifying the inflammation of arthritis through the Th1/Th17 response. The obese CIA murine model will be an important tool when we investigate the effect of several therapeutic target molecules to treat RA.
arthritis, experimental; inflammation; mice; obesity; Th17 cells
Accumulating evidence suggests that Th17 cells play a role in the development of chronic allograft injury in transplantation of various organs. However, the influence of current immunosuppressants on Th17-associated immune responses has not been fully investigated. We prospectively investigated the changes in Th17 cells in peripheral blood mononuclear cells (PBMCs) collected before and 1 and 3 months after KT in 26 patients and we investigated the suppressive effect of tacrolimus on Th17 in vitro. In the early posttransplant period, the percentage of Th17 cells and the proportion of IL-17-producing cells in the effector memory T cells (TEM) were significantly increased at 3 months after transplantation compared with before transplantation (P<0.05), whereas Th1/Th2 cells and TEM cells were significantly decreased. The degree of increase in Th17 during the early posttransplant period was significantly associated with allograft function at 1 year after transplantation (r = 0.4, P<0.05). In vitro, tacrolimus suppressed Th1 and Th2 cells in a concentration-dependent manner, but did not suppress Th17 cells even at high concentration. This suggests that current immunosuppression based on tacrolimus is inadequate to suppress Th17 cells in KTRs, and dysregulation of Th17 may be associated with the progression of CAD.
The study was undertaken to investigate the interrelation of toll-like receptor (TLR) and interleukin (IL)-17 in the salivary glands of patients with primary Sjogren's syndrome (pSS) and to determine the role of TLR and IL-17 in the pathophysiology of pSS.
The expressions of various TLRs, IL-17 and the cytokines involved in Th17 cell differentiation including IL-6, IL-23, tumor necrosis factor-alpha (TNF-α) and IL-1β were examined by immunohistochemistry in salivary glands of pSS patients. The IL-17 producing CD4+ T cells (Th17 cells) were examined by flow cytometry and confocal staining in peripheral mononuclear blood cells (PMBCs) and salivary glands of pSS patients. After PBMCs were treated with TLR specific ligands, the induction of IL-17 and IL-23 was determined using real-time PCR and ELISA. The signaling pathway that mediates the TLR2 stimulated production of IL-17 and IL-23 was investigated by using treatment with specific signaling inhibitors.
We showed that TLR2, TLR4, TLR6, IL-17 and the cytokines associated with Th17 cells were highly expressed in salivary glands of pSS patients but not in controls. The expressions of TLR2, TLR4 and TLR6 were observed in the infiltrating mononuclear cells and ductal epithelial cells, whereas IL-17 was mainly observed in infiltrating CD4+ T cells. The number of IL-17 producing CD4+ T cells was significantly higher in pSS patients both in PBMCs and minor salivary glands. The stimulation of TLR2, TLR4 and TLR6 additively induced the production of IL-17 and IL-23 from the PBMCs of pSS patients especially in the presence of TLR2 stimulation. IL-6, signal transducer and activator of transcription 3 (STAT3) and nuclear factor-kappaB (NF-kB) pathways were implicated in the TLR2 stimulated IL-17 and IL-23.
Our data demonstrate that TLR2 ligation induces the production of IL-23/IL-17 via IL-6, STAT3 and NF-kB pathway in pSS. Therefore, therapeutic strategies that target TLR/IL-17 pathway might be strong candidates for treatment modalities of pSS.
The aim of this study was to evaluate whether the Th17 and Treg cell infiltration into allograft tissue is associated with the severity of allograft dysfunction and tissue injury in acute T cell-mediated rejection (ATCMR). Seventy-one allograft tissues with biopsy-proven ATCMR were included. The biopsy specimens were immunostained for FOXP3 and IL-17. The allograft function was assessed at biopsy by measuring serum creatinine (Scr) concentration, and by applying the modified diet in renal disease (MDRD) formula, which provides the estimated glomerular filtration rate (eGFR). The severity of allograft tissue injury was assessed by calculating tissue injury scores using the Banff classification. The average numbers of infiltrating Treg and Th17 cells were 11.6 ± 12.2 cells/mm2 and 5.6 ± 8.0 cells/mm2, respectively. The average Treg/Th17 ratio was 5.6 ± 8.2. The Treg/Th17 ratio was significantly associated with allograft function (Scr and MDRD eGFR) and with the severity of interstitial injury and tubular injury (P < 0.05, all parameters). In separate analyses of the number of infiltrating Treg and Th17 cells, Th17 cell infiltration was significantly associated with allograft function and the severity of tissue injury. By contrast, Treg cell infiltration was not significantly associated with allograft dysfunction or the severity of tissue injury. The results of this study show that higher infiltration of Th17 cell compared with Treg cell is significantly associated with the severity of allograft dysfunction and tissue injury.
FOXP3 protein, human; graft rejection; interleukin-17; Th17 cells; T-lymphocytes, regulatory; transplantation, homologous
Osteoarthritis (OA) is an age-related joint disease that is characterized by degeneration of articular cartilage and chronic pain. Oxidative stress is considered one of the pathophysiological factors in the progression of OA. We investigated the effects of grape seed proanthocyanidin extract (GSPE), which is an antioxidant, on monosodium iodoacetate (MIA)-induced arthritis of the knee joint of rat, which is an animal model of human OA. GSPE (100 mg/kg or 300 mg/kg) or saline was given orally three times per week for 4 weeks after the MIA injection. Pain was measured using the paw withdrawal latency (PWL), the paw withdrawal threshold (PWT) and the hind limb weight bearing ability. Joint damage was assessed using histological and microscopic analysis and microcomputerized tomography. Matrix metalloproteinase-13 (MMP13) and nitrotyrosine were detected using immunohistochemistry. Administration of GSPE to the MIA-treated rats significantly increased the PWL and PWT and this resulted in recovery of hind paw weight distribution (P < 0.05). GSPE reduced the loss of chondrocytes and proteoglycan, the production of MMP13, nitrotyrosine and IL-1β and the formation of osteophytes, and it reduced the number of subchondral bone fractures in the MIA-treated rats. These results indicate that GSPE is antinociceptive and it is protective against joint damage in the MIA-treated rat model of OA. GSPE could open up novel avenues for the treatment of OA.
antioxidants; grape seed proanthocyanidins; inflammation; interleukin-1β; osteoarthritis