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Mo1692 Vascular Endothelial Transient Receptor Potential Vanilloid 4 Links Colonic Inflammation in Dextran Sulfate Sodium-Induced Colitis Model Mice
Mo1694 Potential Role of Palmitoleate in Inflammatory Bowel Disease Hiroko Fukuda, Fuminao Takeshima, Yuko Akazawa, Tomohito Morisaki, Kayoko Matsushima, Hitomi Minami, Naoyuki Yamaguchi, Ken Ohnita, Hajime Isomoto, Kazuhiko Nakao Background: Palmitoleate (PO), an w7 unsaturated fatty acid produced and released by adipose tissue, may serve as a lipokine that contributes to improvements in insulin sensitivity and regulation of inflammation in mouse models. Aims: The present study sought to evaluate PO levels in serum and mesenteric adipose tissue in patients with inflammatory bowel disease (IBD). We next sought to determine whether PO is able to inhibit inflammation in dextran sodium sulfate (DSS)-induced colitis in mice. Methods: 1) Serum samples were obtained from patients with Crohn's disease (CD; n = 37) or ulcerative colitis (UC; n = 25) and from healthy volunteers (CO; n = 22). Mesenteric adipose tissue specimens were obtained from 6 patients with CD, 4 with UC, and 7 with colon cancer (CC) who had undergone surgical resection. PO levels were analyzed by gas chromatography. 2) Mice were provided 3% DSS solution dissolved in distilled water for 5 days (Day 1-5). Either vehicle (1%BSA) or PO (600mg/kg) was administered intraperitoneally from day 1 to day 14. The length and histological inflammatory grade of colon were then analyzed. Results: 1) Serum PO concentrations were significantly higher in patients with CD (69.6±7.5 μg/ml) than in patients with UC (51.2±5.1 μg/ml; P = 0.03) or CO (45.9±3.4 μg/ml; P = 0.0001) (Figure 1). Mean concentration of PO in mesenteric adipose tissue from fat wrapping of patients with CD (17.8±1.8 μg/mg) was significantly higher than that from unaffected intestine of patients with CD (9.5±2.0 μg/mg; P = 0.0005) or CC (7.9±1.4 μg/mg; P = 0.001). 2) Administration of PO significantly reduced histological inflammatory grade of DSS-induced colitis in mice (Figure 2). Conclusion: 1) Serum and mesenteric adipose tissue concentrations are elevated in patients with CD, suggesting that PO may aid in auxiliary diagnosis of CD. 2) Administration of PO attenuates the inflammation of DSS-induced colitis in mice. PO may also be involved in the regulation of intestinal inflammation in humans.
Effect of oral administration on colonic inflammatory lesions and gene expression in mice with DSS colitis. (A.) Representative micrographs of colonic sections of (A,D) control (B, E) DSS, and (C, F) BT-11 treated DSS mice. (B) Colonic gene expression to assess levels of TNFα. Statistically significant differences (p<0.05) are indicated with an asterisk (n=10). Mo1692 Vascular Endothelial Transient Receptor Potential Vanilloid 4 Links Colonic Inflammation in Dextran Sulfate Sodium-Induced Colitis Model Mice Kenjiro Matsumoto, Riho Yamaba, Daichi Utsumi, Kikuko Amagase, Makoto Tominaga, Shinichi Kato BACKGROUND & AIMS: Transient receptor potential vanilloid 4 (TRPV4) is a nonselective cation channel, and involved in physical sensing in various types of tissues. TRPV4 is expressed in sensory neuron and vascular endothelial cells in various organs. In gastrointestinal tracts, TRPV4 activation in epithelial cells increases in intracellular calcium concentrations and induces colitis. However, the localization and the role of the TRPV4 channel expressed in vascular endothelial cells in colitis are still poorly defined. In the present study, we investigated the alteration of TRPV4 expression in the colonic vascular endothelial cells during dextran sulfate sodium (DSS)-induced colitis. METHODS: Eight week-old wild type (WT) and TRPV4 knock-out (TRPV4 KO) mice were used. Colitis was induced by 2% DSS solution given as drinking water for 7 days. The disease activity index (DAI) was evaluated during the treatment, while colon length, histological damage, and myeloperoxidase (MPO) activity were examined post-DSS treatment. Immunohistochemical analysis was performed in distal colon. TRPV4-immunoreactivity was detected by using immunohistochemical staining with fluorescein-conjugated tyramide amplification. CD31, CD105, CD11b, CD68, Ly6B.2, and VEGF receptor-2 were detected by indirect staining with their specific antibodies. Vascular leakage was investigated using Evans blue dye extrusion assay. RESULTS: TRPV4 KO mice protected against DSS-induced weight loss, neutrophil (MPO), colon shortening, diarrhea, occult-fecal blood, and histological damage. TRPV4 immunoreactivities were detected mostly in epithelial cells of normal distal colon. DSS treatment drastically increased TRPV4 expression in vascular endothelial cells of mucosa and submucosal layer which colocalized with CD31, CD105, and VEGF receptor-2, but not epithelial cells. Repeated intrarectal and intravenous administration of TRPV4 agonist GSK1016790A exacerbated the severity of DSS colitis. Increased vascular permeability was observed following single intravenous administration of GSK1016790A in DSS colitis and this effect was abolished with TRPV4 antagonist RN1734. CD11b, CD68, Ly6B.2 immunopositive cells were detected around TRPV4 positive vascular endothelial cells in mucosa and submucosal layer in DSS colitis. CONCLUSION: These findings indicate that the alteration of TRPV4 in vascular endothelial cells may contribute to progression of colonic inflammation via increasing vascular permeability. Mo1693 Activation of Bone Marrow-Derived TRPV4-Expressing M2 Macrophages Promotes Intestinal Contraction Jialie Luo, Weihua Yu, Yujin Zhang, Jizhong Cheng, Karen S. Uray, Aihua Qian, Shijin Yin, Yang Xia, Roger O'Neil, Hongzhen Hu Intestinal macrophages are crucial sentinels for maintaining intestinal homeostasis as well as regulating intestinal function through paracrine signaling of inflammatory mediators. Activation of the innate immune system by intestinal inflammation and surgery often causes ileus. TRPV4 is a non-selective cation channel activated by osmotic stress and a variety of inflammatory mediators in the arachidonic acid pathway besides serving as a molecular sensor for warm temperature. Previous studies have shown that TRPV4 is a key player in inflammatory pain, visceral hypersensitivity as well as GI inflammation. However, the cellular and molecular mechanisms underlying TRPV4-mediated responses in the GI tract are not completely understood. Here we show that TRPV4 is selectively expressed by a subset of CD11b+ and CD206+ bone marrow-derived intestinal M2 macrophages. Live cell calcium imaging and whole-cell patch-clamp experiments also detected TRPV4-mediated intracellular
S-687
AGA Abstracts
AGA Abstracts
calcium response and membrane current in freshly isolated intestinal macrophages. Surprisingly, selective activation of TRPV4-expressing M2 macrophages elicited a robust contraction of mouse intestinal strips through the cyclooxygenase (COX) /prostaglandin E2 (PGE2) signaling pathway. The TRPV4-mediated contractile response was abolished by genetic ablation or pharmacological inhibition of the TRPV4 function. Importantly, TRPV4-mediated contractile response was markedly enhanced by chemically-induced intestinal inflammation and bacterial endotoxin lipopolysaccharide (LPS) which was abolished by genetic ablation or pharmacological inhibition of TRL4 receptor function. Our results reveal a novel function of the TRPV4-expressing intestinal M2 macrophages and potentially provide a new drug target for improving inflammation-related intestinal dysmotilities.
Effect of oral administration on colonic inflammatory lesions and gene expression in mice with DSS colitis. (A.) Representative micrographs of colonic sections of (A,D) control (B, E) DSS, and (C, F) BT-11 treated DSS mice. (B) Colonic gene expression to assess levels of TNFα. Statistically significant differences (p<0.05) are indicated with an asterisk (n=10). Mo1692 Vascular Endothelial Transient Receptor Potential Vanilloid 4 Links Colonic Inflammation in Dextran Sulfate Sodium-Induced Colitis Model Mice Kenjiro Matsumoto, Riho Yamaba, Daichi Utsumi, Kikuko Amagase, Makoto Tominaga, Shinichi Kato BACKGROUND & AIMS: Transient receptor potential vanilloid 4 (TRPV4) is a nonselective cation channel, and involved in physical sensing in various types of tissues. TRPV4 is expressed in sensory neuron and vascular endothelial cells in various organs. In gastrointestinal tracts, TRPV4 activation in epithelial cells increases in intracellular calcium concentrations and induces colitis. However, the localization and the role of the TRPV4 channel expressed in vascular endothelial cells in colitis are still poorly defined. In the present study, we investigated the alteration of TRPV4 expression in the colonic vascular endothelial cells during dextran sulfate sodium (DSS)-induced colitis. METHODS: Eight week-old wild type (WT) and TRPV4 knock-out (TRPV4 KO) mice were used. Colitis was induced by 2% DSS solution given as drinking water for 7 days. The disease activity index (DAI) was evaluated during the treatment, while colon length, histological damage, and myeloperoxidase (MPO) activity were examined post-DSS treatment. Immunohistochemical analysis was performed in distal colon. TRPV4-immunoreactivity was detected by using immunohistochemical staining with fluorescein-conjugated tyramide amplification. CD31, CD105, CD11b, CD68, Ly6B.2, and VEGF receptor-2 were detected by indirect staining with their specific antibodies. Vascular leakage was investigated using Evans blue dye extrusion assay. RESULTS: TRPV4 KO mice protected against DSS-induced weight loss, neutrophil (MPO), colon shortening, diarrhea, occult-fecal blood, and histological damage. TRPV4 immunoreactivities were detected mostly in epithelial cells of normal distal colon. DSS treatment drastically increased TRPV4 expression in vascular endothelial cells of mucosa and submucosal layer which colocalized with CD31, CD105, and VEGF receptor-2, but not epithelial cells. Repeated intrarectal and intravenous administration of TRPV4 agonist GSK1016790A exacerbated the severity of DSS colitis. Increased vascular permeability was observed following single intravenous administration of GSK1016790A in DSS colitis and this effect was abolished with TRPV4 antagonist RN1734. CD11b, CD68, Ly6B.2 immunopositive cells were detected around TRPV4 positive vascular endothelial cells in mucosa and submucosal layer in DSS colitis. CONCLUSION: These findings indicate that the alteration of TRPV4 in vascular endothelial cells may contribute to progression of colonic inflammation via increasing vascular permeability. Mo1693 Activation of Bone Marrow-Derived TRPV4-Expressing M2 Macrophages Promotes Intestinal Contraction Jialie Luo, Weihua Yu, Yujin Zhang, Jizhong Cheng, Karen S. Uray, Aihua Qian, Shijin Yin, Yang Xia, Roger O'Neil, Hongzhen Hu Intestinal macrophages are crucial sentinels for maintaining intestinal homeostasis as well as regulating intestinal function through paracrine signaling of inflammatory mediators. Activation of the innate immune system by intestinal inflammation and surgery often causes ileus. TRPV4 is a non-selective cation channel activated by osmotic stress and a variety of inflammatory mediators in the arachidonic acid pathway besides serving as a molecular sensor for warm temperature. Previous studies have shown that TRPV4 is a key player in inflammatory pain, visceral hypersensitivity as well as GI inflammation. However, the cellular and molecular mechanisms underlying TRPV4-mediated responses in the GI tract are not completely understood. Here we show that TRPV4 is selectively expressed by a subset of CD11b+ and CD206+ bone marrow-derived intestinal M2 macrophages. Live cell calcium imaging and whole-cell patch-clamp experiments also detected TRPV4-mediated intracellular
S-687
AGA Abstracts
AGA Abstracts
calcium response and membrane current in freshly isolated intestinal macrophages. Surprisingly, selective activation of TRPV4-expressing M2 macrophages elicited a robust contraction of mouse intestinal strips through the cyclooxygenase (COX) /prostaglandin E2 (PGE2) signaling pathway. The TRPV4-mediated contractile response was abolished by genetic ablation or pharmacological inhibition of the TRPV4 function. Importantly, TRPV4-mediated contractile response was markedly enhanced by chemically-induced intestinal inflammation and bacterial endotoxin lipopolysaccharide (LPS) which was abolished by genetic ablation or pharmacological inhibition of TRL4 receptor function. Our results reveal a novel function of the TRPV4-expressing intestinal M2 macrophages and potentially provide a new drug target for improving inflammation-related intestinal dysmotilities.