Tomoharu Ohkawara

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.

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.

iTRAQ-based proteomic identification of leucine-rich α-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 α-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 Crohns 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.

Serum leucine-rich alpha-2 glycoprotein is a disease activity biomarker in ulcerative colitis

Background: Reliable biomarkers for monitoring disease activity have not been clinically established in ulcerative colitis (UC). This study aimed to investigate whether levels of serum leucine‐rich alpha‐2 glycoprotein (LRG), identified recently as a potential disease activity marker in Crohns disease and rheumatoid arthritis, correlate with disease activity in UC. Methods: Serum LRG concentrations were determined by enzyme‐linked immunosorbent assay (ELISA) in patients with UC and healthy controls (HC) and were evaluated for correlation with disease activity. Expression of LRG in inflamed colonic tissues from patients with UC was analyzed by western blotting and immunohistochemistry. Interleukin (IL)‐6‐independent induction of LRG was investigated using IL‐6‐deficient mice by lipopolysaccharide (LPS)‐mediated acute inflammation and dextran sodium sulfate (DSS)‐induced colitis. Results: Serum LRG concentrations were significantly elevated in active UC patients compared with patients in remission (P < 0.0001) and HC (P < 0.0001) and were correlated with disease activity in UC better than C‐reactive protein (CRP). Expression of LRG was increased in inflamed colonic tissues in UC. Tumor necrosis factor alpha (TNF‐&agr;), IL‐6, and IL‐22, serum levels of which were elevated in patients with active UC, could induce LRG expression in COLO205 cells. Serum LRG levels were increased in IL‐6‐deficient mice with LPS‐mediated acute inflammation and DSS‐induced colitis. Conclusions: Serum LRG concentrations correlate well with disease activity in UC. LRG induction is robust in inflamed colons and is likely to involve an IL‐6‐independent pathway. Serum LRG is thus a novel serum biomarker for monitoring disease activity in UC and is a promising surrogate for CRP. (Inflamm Bowel Dis 2012;)

Luteolin, a Flavonoid, Inhibits CD40 Ligand Expression by Activated Human Basophils

Background: We have previously shown that flavonoids such as luteolin, apigenin and fisetin inhibit interleukin 4 and interleukin 13 production. In this study, we investigated whether luteolin can suppress CD40 ligand expression by basophils. Methods: A human basophilic cell line, KU812, was stimulated with A23187 and phorbol myristate acetate (PMA) with or without various concentrations of luteolin or other flavonoids for 12 h, and CD40 ligand expression was analyzed by FACS. The effect of luteolin on CD40 ligand mRNA expression was studied by semiquantitative reverse transcription PCR analysis. In addition, CD40 ligand expression was also measured in purified basophils that had been stimulated for 12 h with A23187 plus PMA with or without various concentrations of luteolin. Results: CD40 ligand expression by KU812 cells was enhanced noticeably in response to A23187 and even more strikingly augmented by A23187 plus PMA. The expression was significantly suppressed by 10 or 30 µM of luteolin, whereas myricetin failed to inhibit. Reverse transcription PCR analyses demonstrated that luteolin inhibited CD40 ligand mRNA expression by stimulated KU812 cells. Of the six flavonoids examined, luteolin, apigenin, fisetin and quercetin at 30 µM showed a significant inhibitory effect on CD40 ligand expression. The incubation of purified basophils with A23187 plus PMA significantly enhanced CD40 ligand expression, and the presence of luteolin again had an inhibitory effect. Conclusions: Luteolin inhibits CD40 ligand expression by activated basophils.

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.

Salt‐inducible kinase 3 deficiency exacerbates lipopolysaccharide‐induced endotoxin shock accompanied by increased levels of pro‐inflammatory molecules in mice

Macrophages play important roles in the innate immune system during infection and systemic inflammation. When bacterial lipopolysaccharide (LPS) binds to Toll‐like receptor 4 on macrophages, several signalling cascades co‐operatively up‐regulate gene expression of inflammatory molecules. The present study aimed to examine whether salt‐inducible kinase [SIK, a member of the AMP‐activated protein kinase (AMPK) family] could contribute to the regulation of immune signal not only in cultured macrophages, but also in vivo. LPS up‐regulated SIK3 expression in murine RAW264.7 macrophages and exogenously over‐expressed SIK3 negatively regulated the expression of inflammatory molecules [interleukin‐6 (IL‐6), nitric oxide (NO) and IL‐12p40] in RAW264.7 macrophages. Conversely, these inflammatory molecule levels were up‐regulated in SIK3‐deficient thioglycollate‐elicited peritoneal macrophages (TEPM), despite no impairment of the classical signalling cascades. Forced expression of SIK3 in SIK3‐deficient TEPM suppressed the levels of the above‐mentioned inflammatory molecules. LPS injection (10 mg/kg) led to the death of all SIK3‐knockout (KO) mice within 48 hr after treatment, whereas only one mouse died in the SIK1‐KO (n = 8), SIK2‐KO (n = 9) and wild‐type (n = 8 or 9) groups. In addition, SIK3‐KO bone marrow transplantation increased LPS sensitivity of the recipient wild‐type mice, which was accompanied by an increased level of circulating IL‐6. These results suggest that SIK3 is a unique negative regulator that suppresses inflammatory molecule gene expression in LPS‐stimulated macrophages.

Overexpression of glypican-1 implicates poor prognosis and their chemoresistance in oesophageal squamous cell carcinoma.

Background:Despite the recent improvements in multimodal therapies for oesophageal squamous cell carcinoma (ESCC), the prognosis remains poor. The identification of suitable biomarkers for predicting the prognosis and chemo-sensitivity is required to develop targeted treatments and improve treatment results.Methods:Proteins highly expressed in ESCC cell lines compared with normal oesophageal cell lines were screened by isobaric tag for relative and absolute quantitation (iTRAQ). We identified glypican-1 (GPC1) as a novel molecule. The clinicopathological characteristics of GPC1 were evaluated by immunohistochemistry using ESCC specimens, and clinical parameters were assessed. The correlation between GPC1 expression levels and chemo-sensitivity were analysed in vitro.Results:In the immunohistochemical assessment of 175 ESCC patients, 98.8% expressed GPC1. These patients demonstrated significantly poorer prognosis compared with patients with low-GPC1 expression by survival assay (P<0.001). Higher chemoresistance was observed in the GPC1 high-expression group. GPC1 expression levels positively correlated with chemo-sensitivity against cis-Diammineplatinum (II) dichloride (CDDP), and are potentially associated with anti-apoptotic function based on alterations in the MAPK downstream signalling pathway and Bcl-2 family member proteins.Conclusions:GPC1 is an independent prognostic factor in ESCC and is a critical molecule for altering the threshold of chemoresistance to CDDP.

Suppressor of cytokine signalling‐1 induces significant preclinical antitumor effect in malignant melanoma cells

Malignant melanoma is the most aggressive form of skin cancer, responsible for the majority of skin cancer‐related deaths. Metastatic melanoma is resistant to surgery, radiation or chemotherapy, and an effective therapy has not yet been established. Our study investigated the therapeutic potential of the suppressor of cytokine signalling‐1 (SOCS‐1), an endogenous inhibitor of the intracellular cytokine signalling pathway, for treating melanoma. Adenovirus vectors encoding the SOCS‐1 gene were used to overexpress SOCS‐1 in three melanoma cell lines (G361, SK‐MEL5 and SK‐MEL28). In G361 and SK‐MEL5, overexpression of SOCS‐1 significantly reduced cell proliferation and induced apoptosis in vitro and in vivo. Furthermore, we indicated that the antiproliferative effect of SOCS‐1 correlated not only with decreased levels of the activation of signal transducer and activator of transcription (STAT)3 but also with increased levels of p53 expression and phosphorylation. These findings indicate the potential for clinical use of SOCS‐1 for melanoma treatment.

Anti-glypican-1 antibody-drug conjugate exhibits potent preclinical antitumor activity against glypican-1 positive uterine cervical cancer

Glypican‐1 (GPC1) is highly expressed in solid tumors, especially squamous cell carcinomas (SCCs), and is thought to be associated with disease progression. We explored the use of a GPC1‐targeted antibody‐drug conjugate (ADC) as a novel treatment for uterine cervical cancer. On immunohistochemical staining, high expression levels of GPC1 were detected in about 50% of uterine cervical cancer tissues and also in a tumor that had relapsed after chemoradiotherapy. Novel anti‐GPC1 monoclonal antibodies were developed, and clone 01a033 was selected as the best antibody for targeted delivery of the cytotoxic agent monomethyl auristatin F (MMAF) into GPC1‐positive cells. The anti‐GPC1 antibody was conjugated with MMAF. On flow cytometry, HeLa and ME180 cervical cancer cells highly expressed GPC1, however, RMG‐I ovarian clear cell cancer cell line showed weak expression. The GPC1‐ADC was rapidly internalized into GPC1‐expressing cells in vitro and was potently cytotoxic to cancer cells highly expressing GPC1. There were no inhibitory effects on cancer cells with low expression of GPC1. In a murine xenograft model, GPC1‐ADC also had significant and potent tumor growth inhibition. GPC1‐ADC–mediated G2/M phase cell cycle arrest was detected, indicating that the dominant antitumor effect in vivo was MMAF‐mediated. The toxicity of GPC‐ADC was tolerable within the therapeutic dose range in mice. Our data showed that GPC1‐ADC has potential as a promising therapy for uterine cervical cancer.