Shogo Takeda

High-Mobility Group Box 1 Inhibits Gastric Ulcer Healing through Toll-Like Receptor 4 and Receptor for Advanced Glycation End Products

High-mobility group box 1 (HMGB1) was initially discovered as a nuclear protein that interacts with DNA as a chromatin-associated non-histone protein to stabilize nucleosomes and to regulate the transcription of many genes in the nucleus. Once leaked or actively secreted into the extracellular environment, HMGB1 activates inflammatory pathways by stimulating multiple receptors, including Toll-like receptor (TLR) 2, TLR4, and receptor for advanced glycation end products (RAGE), leading to tissue injury. Although HMGB1’s ability to induce inflammation has been well documented, no studies have examined the role of HMGB1 in wound healing in the gastrointestinal field. The aim of this study was to evaluate the role of HMGB1 and its receptors in the healing of gastric ulcers. We also investigated which receptor among TLR2, TLR4, or RAGE mediates HMGB1’s effects on ulcer healing. Gastric ulcers were induced by serosal application of acetic acid in mice, and gastric tissues were processed for further evaluation. The induction of ulcer increased the immunohistochemical staining of cytoplasmic HMGB1 and elevated serum HMGB1 levels. Ulcer size, myeloperoxidase (MPO) activity, and the expression of tumor necrosis factor α (TNFα) mRNA peaked on day 4. Intraperitoneal administration of HMGB1 delayed ulcer healing and elevated MPO activity and TNFα expression. In contrast, administration of anti-HMGB1 antibody promoted ulcer healing and reduced MPO activity and TNFα expression. TLR4 and RAGE deficiency enhanced ulcer healing and reduced the level of TNFα, whereas ulcer healing in TLR2 knockout (KO) mice was similar to that in wild-type mice. In TLR4 KO and RAGE KO mice, exogenous HMGB1 did not affect ulcer healing and TNFα expression. Thus, we showed that HMGB1 is a complicating factor in the gastric ulcer healing process, which acts through TLR4 and RAGE to induce excessive inflammatory responses.

NLRP3 inflammasome has a protective effect against oxazolone-induced colitis: a possible role in ulcerative colitis.

The inflammasomes induce maturation of pro-interleukin-1β (IL-1β) and pro-IL-18. We investigated roles of the NLRP3 inflammasome in the pathogenesis of ulcerative colitis (UC). After induction of oxazolone-induced colitis, a mouse UC model, colonic tissues were assayed for inflammatory mediators. Histological studies were performed on inflamed colonic tissue from mice and UC patients. Histological severity of murine colitis peaked on day 1, accompanied by an increase in the expression of Th2 cytokines including IL-4 and IL-13. Oxazolone treatment stimulated maturation of pro-caspase-1 and pro-IL-1β, while it reduced IL-18 expression. Either exogenous IL-1β or IL-18 ameliorated the colitis with or without reduction in Th2 cytokine expression, respectively. Induction of colitis decreased MUC2 expression, which was reversed by administration of IL-18, but not IL-1β. Compared to wild-type mice, NLRP3−/− mice exhibited higher sensitivity to oxazolone treatment with enhancement of Th2 cytokine expression and reduction of mature IL-1β and IL-18 production; this phenotype was rescued by exogenous IL-1β or IL-18. Immunofluorescent studies revealed positive correlation of NLRP3 expression with disease severity in UC patients, and localization of the inflammasome-associated molecules in macrophages. The NLRP3 inflammasome-derived IL-1β and IL-18 may play a protective role against UC through different mechanisms.

Colchicine prevents NSAID-induced small intestinal injury by inhibiting activation of the NLRP3 inflammasome

The inflammasome is a large, multiprotein complex that consists of a nucleotide-binding oligomerization domain-like receptor (NLR), an apoptosis-associated speck-like protein containing a caspase recruitment domain, and pro-caspase-1. Activation of the inflammasome results in cleavage of pro-caspase-1 into cleaved caspase-1, which promotes the processing of pro-interleukin (IL)-1β into mature IL-1β. We investigated the effects of colchicine on non-steroidal anti-inflammatory drug (NSAID)-induced small intestinal injury and activation of the NLR family pyrin domain-containing 3 (NLRP3) inflammasome. Colchicine treatment inhibited indomethacin-induced small intestinal injury by 86% (1 mg/kg) and 94% (3 mg/kg) as indicated by the lesion index 24 h after indomethacin administration. Colchicine inhibited the protein expression of cleaved caspase-1 and mature IL-1β, without affecting the mRNA expression of NLRP3 and IL-1β. Although treatment with recombinant IL-1β (0.1 μg/kg) did not change the severity of small intestinal damage, the preventive effects of colchicine were abolished by supplementation with the same dose of recombinant IL-1β. Indomethacin-induced small intestinal damage was reduced by 77%, as determined by the lesion index in NLRP3−/− mice, and colchicine treatment failed to inhibit small intestinal damage in NLRP3−/− mice. These results demonstrate that colchicine prevents NSAID-induced small intestinal injury by inhibiting activation of the NLRP3 inflammasome.

Toll-like receptor 2 mediates ischemia-reperfusion injury of the small intestine in adult mice.

Toll-like receptor 2 (TLR2) recognizes conserved molecular patterns associated with both gram-negative and gram-positive bacteria, and detects some endogenous ligands. Previous studies demonstrated that in ischemia-reperfusion (I/R) injury of the small intestine, the TLR2-dependent signaling exerted preventive effects on the damage in young mice, but did not have a significant effect in neonatal mice. We investigated the role of TLR2 in adult ischemia-reperfusion injury in the small intestine. Wild-type and TLR2 knockout mice at 16 weeks of age were subjected to intestinal I/R injury. Some wild-type mice received anti-Ly-6G antibodies to deplete circulating neutrophils. In wild-type mice, I/R induced severe small intestinal injury characterized by infiltration by inflammatory cells, disruption of the mucosal epithelium, and mucosal bleeding. Compared to wild-type mice, TLR2 knockout mice exhibited less severe mucosal injury induced by I/R, with a 35%, 33%, and 43% reduction in histological grading score and luminal concentration of hemoglobin, and the numbers of apoptotic epithelial cells, respectively. The I/R increased the activity of myeloperoxidase (MPO), a marker of neutrophil infiltration, and the levels of mRNA expression of tumor necrosis factor-α (TNF-α), intercellular adhesion molecule-1 (ICAM-1), and cyclooxygenase-2 (COX-2) in the small intestine of the wild-type mice by 3.3-, 3.2-, and 13.0-fold, respectively. TLR2 deficiency significantly inhibited the I/R-induced increase in MPO activity and the expression of mRNAs for TNF-α and ICAM-1, but did not affect the expression of COX-2 mRNA. I/R also enhanced TLR2 mRNA expression by 2.9-fold. TLR2 proteins were found to be expressed in the epithelial cells, inflammatory cells, and endothelial cells. Neutrophil depletion prevented intestinal I/R injury in wild-type mice. These findings suggest that TLR2 may mediate I/R injury of the small intestine in adult mice via induction of inflammatory mediators such as TNF-α and ICAM-1.

Reduction of prostaglandin transporter predicts poor prognosis associated with angiogenesis in gastric adenocarcinoma

Prostaglandin (PG) E2 promotes gastrointestinal carcinogenesis and tumor progression. The total amount of biologically active PGE2 in tissues is determined by a balance of PG biosynthesis and degradation pathways, which involve the PG transporter (PGT). We investigated PGT in gastric adenocarcinoma by determining its expression pattern and examining associations of PGT with prognosis and tumor angiogenesis.

Strawberry seed extract and its major component, tiliroside, promote ceramide synthesis in the stratum corneum of human epidermal equivalents

The activation of peroxisomeproliferator-activated receptor (PPAR) α can stimulate the expression of ceramide-related enzymes, and a major component of strawberry seed extract (SSE) tiliroside enhances the expression of PPARα. We determined whether SSE and tiliroside may stimulate ceramide synthesis in the stratum corneum (SC) of the human epidermal equivalents (HEEs) culture model. Treatment with SSE at 1.0 and 3.0 μg/mL elicited a significant increase in the total ceramide content in the SC, which was accompanied by a significant increase in almost all ceramide species except for ceramide [EOS] and [AP]. Treatment with tiliroside at 0.3 μg/mL slightly accentuated the total ceramide content in the SC together with a significant increase in the ceramide [NS, NDS] content. Messenger RNA analysis demonstrated that SSE at 1 or 3 μg/mL significantly stimulated the gene expression of serine palmitoyltransferase (SPT) 2, ceramide synthase (CerS) 3, glucosylceramide synthase (GCS), and β-glucocerebrosidase (GBA) but not of SPT1, sphingomyelin synthase (SMS) 1/2 and acid sphingomyelinase (ASM). In contrast, tiliroside elicited significant increases in the gene expression levels of GCS and GBA only at 0.3 and/or 0.1 μg/mL. Western blotting analysis revealed that both SSE and tiliroside enhanced the protein expression levels of GCS and GBA but not of SPT2 at 1 or 3 and 0.1 or 0.3 μg/mL, respectively. These findings suggested that both SSE and tiliroside have a distinct potential to stimulate the level of ceramide [NS, NDS] in the SC by enhancing the expression of GCS and GBA. The higher stimulatory effect with SSE than tiliroside on SC ceramide synthesis correlates with the significant increase observed with SSE but not tiliroside in the gene expression levels of SPT2 and CerS3. Therefore, it is anticipated that SSE is effective in improving skin barrier function and moisture retention in several ceramide-deficit skin conditions, including surfactant-induced roughened skin, xerosis, and atopic dermatitis.

Sa1993a Reduced Expression of Prostaglandin Transporter Promotes Angiogenesis in Gastric Cancer

Background & Aims: Colorectal cancer (CRC) cells (unlike normal colonic epithelial cells) secrete VEGF, which drives these cells proliferation and promotes tumor-related angiogenesis. The mechanism(s) of increased, aberrant VEGF expression in CRC cells is not known, but is likely related to transcriptional activation of VEGF gene.We hypothesized that: 1) upregulated importin-α in CRC cells (which facilitates nuclear transport of transcription factors: HIF1α and CREB, and is essential for VEGF gene promoter activation) is the underlying mechanism for increased VEGF expression in these cells and CRC cell proliferation, and, 2) inhibition and/or silencing of importin-α in CRC cells will inhibit VEGF gene activation and CRC cell proliferation. Ivermectin is a specific inhibitor of importin α nuclear transport (Biochem J. 2012: 1;443(3):851-6). We examined whether treatment of CRC cell lines with ivermectin could inhibit CRC cell growth. Methods: We used: (a) human CRC cell lines HCT116 & HT29 and (b) normal colonic epithelial cells NCM356 & NCM460. We treated cultured CRC cells with ivermectin (50 μM, 6 hr; specific inhibitor of importin-α nuclear transport), with importin α specific siRNA or control RNA (100nM, 48 hr). Add-back studies included treatment with exogenous VEGF (20ng/ml). Studies: 1) mRNA and protein expression of importin-α and VEGF by Real-Time RT-PCR, and/or Western blotting and immunostaining, respectively; 2) VEGF secretion into culture medium by ELISA; 3) translocation of importin to the nucleus in CRC vs. normal cells; and 4) cell proliferation by BrdU assay. Results: 1) CRC cell lines express high levels of VEGF and secrete large amounts of VEGF (up to 1530 pg/ml) into culture medium at 24 hours vs. normal epithelial cells, which only secrete minimal VEGF ( 40% (p< 0.05); 3) Selective inhibition of importin-α in CRC cells using ivermectin significantly reduced VEGF expression by ~3-fold (p<0.01) and proliferation of these cells by 2.4-fold (p<0.01). Treatment with exogenous VEGF partly reversed inhibited by ivermectin cell proliferation; 4) Importin-α silencing in CRC cells significantly reduced VEGF expression and proliferation of these cells by 2.2-fold and 2fold (both p<0.01), respectively; treatment with exogenous VEGF following importin-α silencing reversed inhibition of cell proliferation by 2-fold (p < 0.01). Conclusions: 1) VEGF gene activation in CRC cells requires functional importin-α; 2) importin-α mediates increased proliferation of CRC cells; downregulation of importin-α with specific siRNA or its inhibition with specific inhibitor ivermectin inhibits CRC cell proliferation; 3) These studies suggest a potential therapeutic role of ivermectin in inhibiting CRC cell proliferation.

Tu1220 Rebamipide Inhibits Indomethacin-Induced Experimental Small Intestinal Injury and the Exacerbation of the Injury Induced by Proton Pump Inhibitor: Possible Involvement of Intestinal Microbiota Modulation by Rebamipide

were decreased 1.5-fold (± 0.2, p<0.02) and 7.1-fold (± 1.4, p<0.01) in the setting of acute Hh inhibition. Finally, mice exposed to LDE treatment for 6 days were predisposed to significant, damaging colitis secondary to 3% DSS challenge as evidenced by increased weight loss (35% vs 15%), increased histological damage and inflammatory infiltrate when compared to solvent treated controls exposed to DSS. Our initial evaluation of the effect of Hh targeted therapies on the gastrointestinal tract indicates that inhibiting epithelial derived Hh signaling leads to a pro-inflammatory immune environment thereby predisposing the GI tract to inflammatory mediated damage when challenged. While targeting the Hh pathway for treatment of malignancies is attractive and powerful, understanding the resultant effect on mucosal immune homeostasis is a critical component to developing safe and tolerable therapies. 1 Sekulic et al NEJM 2012; 366:2171-79. 2 Chang et al. J. Am Acad Dermatol. 2013 Nov 1, S0190-9622 (13). 3 Keating GM Drugs 2012 72(11)1535-41.