The influence of excessive IL-6 production in vivo on the development and function of Foxp3+ regulatory T cells.

IL-6 is a proinflammatory cytokine and its overproduction is implicated in a variety of inflammatory disorders. Recent in vitro analyses suggest that IL-6 is a key cytokine that determines the balance between Foxp3(+) regulatory T cells (Tregs) and Th17 cells. However, it remains unclear whether excessive IL-6 production in vivo alters the development and function of Foxp3(+) Tregs. In this study, we analyzed IL-6 transgenic (Tg) mice in which serum IL-6 levels are constitutively elevated. Interestingly, in IL-6 Tg mice, whereas peripheral lymphoid organs were enlarged, and T cells exhibited activated phenotype, Tregs were not reduced but rather increased compared with wild-type mice. In addition, Tregs from Tg mice normally suppressed proliferation of naive T cells in vitro. Furthermore, Tregs cotransferred with naive CD4 T cells into SCID-IL-6 Tg mice inhibited colitis as successfully as those transferred into control SCID mice. These results indicate that overproduction of IL-6 does not inhibit development or function of Foxp3(+) Tregs in vivo. However, when naive CD4 T cells alone were transferred, Foxp3(+) Tregs retrieved from SCID-IL-6 Tg mice were reduced compared with SCID mice. Moreover, the Helios(-) subpopulation of Foxp3(+) Tregs, recently defined as extrathymic Tregs, was significantly reduced in IL-6 Tg mice compared with wild-type mice. Collectively, these results suggest that IL-6 overproduced in vivo inhibits inducible Treg generation from naive T cells, but does not affect the development and function of natural Tregs.

Down-regulation of hepcidin resulting from long-term treatment with an anti-IL-6 receptor antibody (tocilizumab) improves anemia of inflammation in multicentric Castleman disease.

Dysregulated production of hepcidin is implicated in anemia of inflammation, whereas interleukin-6 (IL-6) is a major inducer of hepcidin production. Overproduction of IL-6 is responsible for pathogenesis of multicentric Castleman disease (MCD), a rare lymphoproliferative disorder accompanied by systemic inflammatory responses and anemia. In this study, we investigated the roles of hepcidin and IL-6 in anemia of inflammation and the long-term effects of anti-IL-6 receptor antibody (tocilizumab) treatment on serum hepcidin and iron-related parameters in MCD patients. We found that tocilizumab treatment resulted in a rapid reduction of serum hepcidin-25 in 5 of 6 MCD patients. Long-term reductions, accompanied by progressive normalization of iron-related parameters and symptom improvement, were observed in 9 of 9 cases 1.5, 3, 6, and 12 months after the start of tocilizumab treatment. In in vitro experiments, IL-6-induced up-regulation of hepcidin mRNA in hepatoma cell lines was completely inhibited by tocilizumab but increased in the presence of patients' sera. Our results suggest that, although multiple factors affect serum hepcidin levels, IL-6 plays an essential role in the induction of hepcidin in MCD. This accounts for the long-term ameliorative effect of IL-6 blockage with tocilizumab on anemia by inhibiting hepcidin production in MCD patients.

Green tea polyphenol epigallocatechin gallate inhibits cell signaling by inducing SOCS1 gene expression.

Therapeutic effects of green tea involve an inhibitory function of its constituent polyphenol epigallocatechin gallate (EGCG) on cell signaling. The specificity and mechanism(s) by which EGCG inhibits cell signaling have remained unclear. Here, we demonstrate that green tea and EGCG induce suppressor of cytokine signaling 1 (SOCS1) gene expression, a negative regulator of specific cell signaling pathways. In mouse immune cells, EGCG induces SOCS1 expression via an oxidative (superoxide) pathway and activation of the signal transducer and activator of transcription 5 transcription factor. EGCG inhibited SOCS1-regulated cell signaling, but this inhibitory effect was abrogated in cells deficient in SOCS1. These findings identify a mechanism by which EGCG inhibits cell signaling with specificity, mediated by induction of the negative regulator SOCS1.

IL-6 blockade inhibits the induction of myelin antigen-specific Th17 cells and Th1 cells in experimental autoimmune encephalomyelitis.

The development of Th17 cells is a key event in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), a murine model of human multiple sclerosis (MS). Previous studies have demonstrated that an IL-6-dependent pathway is involved in the differentiation of Th17 cells from naïve CD4-positive T cells in vitro. However, the role of IL-6 in vivo in the development of Th17 cells in EAE has remained unclear. In the present study, we found that IL-6 blockade by treatment with an anti-IL-6 receptor monoclonal antibody (anti-IL-6R mAb) inhibited the development of EAE and inhibited the induction of myelin oligodendrocyte glycoprotein (MOG) peptide-specific CD4-positive, CD8-positive, and Th17 T cells, in inguinal lymph nodes. Thus, the protective effect of IL-6 blockade in EAE is likely to be mediated via the inhibition of the development of MOG-peptide-specific Th17 cells and Th1 cells, which in turn leads to reduced infiltration of T cells into the CNS. These findings indicate that anti-IL-6R mAb treatment might represent a novel therapy for human MS.

iTRAQ-based proteomic identification of leucine-rich alpha-2 glycoprotein as a novel inflammatory biomarker in autoimmune diseases.

OBJECTIVE: To identify a novel serum biomarker of disease activity in inflammatory autoimmune disorders. METHODS: Sera obtained from rheumatoid arthritis (RA) patients before and after anti-TNF therapy were analysed by iTRAQ (isobaric tags for relative and absolute quantitation) quantitative proteomic analysis and further validated by ELISA. RESULTS: Of 326 proteins identified by proteomic analysis, increased serum levels of leucine-rich alpha-2 glycoprotein (LRG) was identified in RA patients before therapy. Serum LRG concentrations were significantly elevated in RA patients compared with healthy controls and decreased after anti-TNF therapy. Furthermore, serum LRG concentrations correlated with disease activity in RA and Crohn's disease (CD). Interestingly, in a subpopulation of patients with active CD and normal C-reactive protein levels, serum LRG concentrations were elevated. CONCLUSIONS: LRG represents a novel serum biomarker for monitoring disease activity during therapy in autoimmune patients, particularly useful in patients with active disease but normal CRP levels.

Fully automated liquid chromatography-mass spectrometry determination of 17beta-estradiol in river water.

Surface modified molecularly imprinted polymers (SM-MIPs) for 17beta-estradiol (E2), utilizing 6-ketoecradiol as a pseudo template were prepared. MIPs for E2 were synthesized using 4-vinyl pyridine and ethylene dimethacrylate as a functional monomer and cross-linking agent, respectively. MIPs selectively retained E2 and provided excellent chromatographic resolution from interfering compounds inherent in river water sample matrices. Therefore, freshly prepared MIPs were applied to quantitative mass spectrometric (negative electrospray ionization mode) detection of low levels of E2 in river water sample. In order to pre-concentrate the target compound for HPLC analysis, column switching was coupled with a pretreatment column packed with the MIPs. The repeatability of actual determinations of river water sample, in which background E2 was not detected, spiked with 50 ng/L of E2 was 2.2% RSD with a detection limit and qualification limit of 1.8 and 5.4 ng/L, respectively. Surface modification of MIP particlefs packed in the pretreatment column provided selective affinity and on-line concentration of low levels of E2 while simultaneously eliminating sample matrix interference, resulting in a significant increase in sensitivity and reproducibility for liquid chromatography-mass spectrometry analysis of E2 in river water sample.

Interleukin-6-producing dermoid cyst associated with multicentric Castleman's disease.

Dysregulated overproduction of interleukin-6 (IL-6) from activated B cells in affected lymph nodes has been implicated in the pathogenesis of multicentric Castleman's disease (MCD), a rare lymphoproliferative disorder accompanied by systemic manifestations. We here report the case of a 32-year-old female presenting with MCD associated with a dermoid cyst in the pelvic cavity. The co-occurrence of MCD and dermoid cyst has not been reported before. Immunohistochemical analysis of the tissue sections showed IL-6 production in CD68-positive macrophage cells, which had infiltrated the dermoid cyst. Removal of the cyst resulted in partial improvement in systemic symptoms accompanied by a decrease in serum IL-6, while complete improvement was obtained by treatment with an anti-IL-6 receptor antibody following resection of the dermoid cyst. To the best of our knowledge, this is the first study to provide evidence of IL-6 production by CD68(+) cells in a dermoid cyst involved in MCD.

Transcriptional complex formation of c-Fos, STAT3, and hepatocyte NF-1 alpha is essential for cytokine-driven C-reactive protein gene expression.

C-reactive protein (CRP) is a sensitive marker and mediator of inflammation, whereas IL-6 blocking therapy can normalize serum levels of CRP in chronic inflammatory diseases. We investigated the precise synergistic induction mechanism of CRP gene expression by IL-1 and IL-6 in Hep3B cells. In the early induction phase, IL-1 inhibited IL-6-mediated CRP gene expression, and NF-kappaB p65 inhibited the luciferase activity of pGL3-CRP by IL-1 plus IL-6 even in the presence of overexpressed STAT3. In the late induction phase, we focused on JNK and p38 activated by IL-1. SP600125 reduced the expression of the CRP gene induced by IL-1 plus IL-6. Unexpectedly, overexpression of c-Fos dramatically enhanced the luciferase activity by IL-1 and IL-6 even though the CRP gene has no AP-1 response element (RE) in its promoter. The augmentative effect of c-Fos required the presence of STAT3 and 3'-hepatocyte NF-1 (HNF-1) RE, which were eliminated by dominant negative STAT3 and HNF-1alpha, respectively. SB203580 inhibited the phosphorylation of c-Fos enhanced by IL-1 plus IL-6, and diminished expression of the CRP gene. Immunoprecipitation, Western blot analysis, the Supershift assay using a CRP oligonucleotide containing STAT3 and 3'-HNF-1 RE, and the chromatin immunoprecipitation assay demonstrated that c-Fos/STAT3/HNF-1alpha forms a complex on the CRP gene promoter. Because human fetus liver cells failed to express c-Fos/STAT3/HNF-1alpha showed no CRP production, transcriptional complex formation of c-Fos/STAT3/HNF-1alpha is essential for the synergistic induction of CRP gene expression by IL-1 plus IL-6. Our findings fully explain the clinical results of IL-6 blocking therapy and are expected to contribute to the development of a therapeutic strategy for chronic inflammatory diseases.

Interleukin-6 blockade suppresses autoimmune arthritis in mice by the inhibition of inflammatory Th17 responses.

OBJECTIVE: To investigate the mechanism of interleukin-6 (IL-6) blockade in autoimmune arthritis, by comparing the effect of anti-IL-6 receptor (anti-IL-6R) monoclonal antibody (mAb) treatment with the effect of soluble tumor necrosis factor (sTNFR)-Fc fusion protein treatment on T helper cell differentiation in collagen-induced arthritis (CIA). METHODS: DBA/1 mice were immunized with type II collagen (CII) to induce arthritis and were left untreated or were treated with anti-IL-6R mAb or TNFR-Fc. T helper cell differentiation and cytokine expression during the development of arthritis in these mice were analyzed. RESULTS: Immunization with CII predominantly increased the frequency of Th17 cells rather than Th1 cells. The frequency of FoxP3+ Treg cells was also increased after immunization. Treatment of mice with CIA with anti-IL-6R mAb on day 0 markedly suppressed the induction of Th17 cells and arthritis development, but treatment with this antibody on day 14 failed to suppress both Th17 differentiation and arthritis. In contrast, treatment of mice with CIA with TNFR-Fc from day 0 to day 14 suppressed neither Th17 differentiation nor arthritis, but treatment from day 21 to day 35 successfully ameliorated arthritis without inhibiting Th17 induction. Neither antibody treatment increased the frequency of Treg cells. CONCLUSION: Our results indicate that the protective effect of IL-6 blockade, but not tumor necrosis factor (TNF) blockade, in CIA correlates with the inhibition of Th17 differentiation. Our findings suggest that IL-6 blockade in rheumatoid arthritis in human is also likely to involve a therapeutic mechanism distinct from that of TNF blockade and thus may represent an alternative therapy for patients in whom the disease is refractory to TNF blockade.

Essential role of STAT3 in cytokine-driven NF-kappaB-mediated serum amyloid A gene expression.

Serum amyloid A (SAA) is a sensitive marker of acute-phase responses and known as a precursor protein of amyloid fibril in amyloid A (AA) (secondary) amyloidosis. Since the serum SAA level is also closely related to activity of chronic inflammatory disease and coronary artery disease, it is important to clarify the exact induction mechanism of SAA from the clinical point of view. Here we provide evidence that STAT3 plays an essential role in cytokine-driven SAA expression, although the human SAA gene shows no typical STAT3 response element (RE) in its promoters. STAT3 and nuclear factor kappaB (NF-kappaB) p65 first form a complex following interleukin (IL)-1 and IL-6 (IL-1+6) stimulation, after which STAT3 interacts with nonconsensus sequences at a 3' site of the SAA gene promoter's NF-kappaB RE. Moreover, co-expression of p300 with STAT3 dramatically enhances the transcriptional activity of SAA. The formation of a complex with STAT3, NF-kappaB p65, and p300 is thus essential for the synergistic induction of the SAA gene by IL-1+6 stimulation. Our findings are expected to aid the understanding of the inflammatory status of AA amyloidosis to aid development of a therapeutic strategy for this disease by means of normalization of serum SAA levels.

Isolation and characterization of Saccharomyces cerevisiae genes differentially expressed under different growth conditions.

The budding yeast Saccharomyces cerevisiae, like many other microorganisms, responds to nutrient starvation by arresting growth and entering into a non-proliferating stationary phase. Studies on the response of S. cerevisiae cells to growth arrest might provide further insight into the non-proliferative states of cells in multi-cellular eukaryotic organisms. Changes might occur at the transcription, translation, and post-translational levels in cells upon entry into the stationary phase. To search for the genes differentially expressed in yeast cells during different growth phases, we have performed systematic Northern hybridization experiments using probes prepared for a large number of genes/ORFs. We have thus isolated and characterized 42 cDNA clones containing genes hyper-expressed in the post-diauxic phase. Some of them have already been characterized, and many others show similarity to known yeast genes or genes of other organisms. However, eleven of them were found to be unrelated to any known genes. We have characterized some of these genes as described below. Also, a possible cis-element for transcriptional regulation was identified.

IL-6 plays a critical role in the synergistic induction of human serum amyloid A (SAA) gene when stimulated with proinflammatory cytokines as analyzed with an SAA isoform real-time quantitative RT-PCR assay system.

Serum amyloid A (SAA) is known to be a precursor of amyloid A (AA) protein in AA (secondary) amyloidosis and SAA1 to be mainly involved in AA amyloidosis. We established an SAA isoform real-time quantitative RT-PCR assay and found that beta-2 microglobulin is more stable as an internal control than GAPDH and beta-actin for our system. Either IL-6 and IL-1beta or IL-6 and TNFalpha, but not IL-1beta and TNFalpha, induced the synergistic induction of SAA1 and SAA2 genes. Anti-IL-6 receptor monoclonal antibody completely inhibited the synergistic induction of SAA1 and SAA2 during triple stimulation with IL-6, IL-1beta, and TNFalpha, but, IL-1 receptor antagonist or anti-TNFalpha monoclonal antibody was only partially inhibited in HepG2, Hep3B, and PLC/PRF/5 cells. Although the SAA1 promoter has no STAT3 consensus sequence, the JAK2 inhibitor-AG490 reduced SAA1 gene expression to 30%, suggesting the involvement of STAT3. We were able to demonstrate that IL-6 plays a critical role in the synergistic induction of human SAA gene when stimulated with proinflammatory cytokines.