Protective action of NADPH oxidase inhibitors and role of NADPH oxidase in pathogenesis of colon inflammation in mice

AIM: To investigate the role of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in colon epithelial cells in the pathogenesis of acute and chronic colon inflammation in a mouse model of dextran sulphate sodium (DSS)-induced colitis.METHODS: Balb/c mice were divided into three groups: 8 mice with acute DSS-induced colitis (3.5% DSS solution; 7 d), 8 mice with chronic DSS-induced colitis (3.5% DSS solution for 5 d + water for 6 d; 4 cycles; total: 44 d) and 12 mice without DSS supplementation as a control group. Primary colonic epithelial cells were isolated using chelation method. The cells were cultivated in the presence of mediators (lipopolysaccharide (LPS), apocynin or diphenyleneiodonium). Viability of cells was assessed by fluorescent microscopy. Production of reactive oxygen species (ROS) by the cells was measured fluorometrically using Amplex Red. Production of tumour necrosis factor-alpha (TNF-α) by the colonic epithelial cells was analysed by ELISA. Nox1 gene expression was assessed by real-time PCR.RESULTS: Our study showed that TNF-α level was increased in unstimulated primary colonic cells both in the acute and chronic colitis groups, whereas decreased viability, increased ROS production, and expression of Nox1 was characteristic only for chronic DSS colitis mice when compared to the controls. The stimulation by LPS increased ROS generation via NADPH oxidase and decreased cell viability in mice with acute colitis. Treatment with NADPH oxidase inhibitors increased cell viability and decreased the levels of ROS and TNF-α in the LPS-treated cells isolated from mice of both acute and chronic colitis groups.CONCLUSION: Our study revealed the importance of NADPH oxidase in the pathogenesis of both acute and chronic inflammation of the colon.     

Icariin Inhibits Intestinal Inflammation of DSS-Induced Colitis Mice Through Modulating Intestinal Flora Abundance and Modulating p-p65/p65 Molecule

BackgroundUlcerative colitis, as a kind of inflammatory bowel disease (IBD) is characterized by abdominal pain. This study aimed to investigate the effect of icariin (ICA) on the intestinal microflora of colitis mice.MethodsFifteen female C57BL/6 mice were randomly divided into the Control group, dextran sodium sulfate (DSS)-induced colitis (DSS) group, and ICA treatment (DSS+ICA) group. The severity of inflammation in DSS-induced colitis mice was evaluated using disease activity scoring (considering weight-loss percentage, stool-shape change, and stool-bleeding scoring). Pathological changes of mice intestinal tract were evaluated using hematoxylin–eosin (HE) staining. Serum levels of TNF-α and IL-6 were detected with enzyme-linked immunosorbent assay. Expressions of p65 and p-p65 (p-p65/p65 ratio) were analyzed using Western blot assay. 16S rDNA sequencing was used to analyze the abundance and composition of intestinal microflora.ResultsCompared with DSS group, ICA significantly improved disease activity (P < .05) and reduced inflammatory damage of colon tissues (P < .05) in DSS-induced colitis mice. Compared with the DSS group, mice in the ICA group demonstrated significant weight and colon length (P < .05). ICA significantly inhibited expressions of IL-6 and TNF-α compared to the DSS group (P < .05). p-p65/p65 ratio in the DSS+ICA group was remarkably enhanced compared to the DSS group (P < .05). ICA significantly reduced the proportion and activity of Bacteroides, Helicobacteraceae, Turicibacter, and significantly increased that of beneficial microflora (Lactobacillus, Lachnospiraceae, Akkermansia), so as improved damages of colon tissues. ConclusionICA can improve intestinal flora abundance and composition of DSS-induced colitis mice, and inhibit tissue damage and inflammatory response through modulating the p-p65/p65 expression.     

Near‐infrared lymphatic imaging demonstrates the dynamics of lymph flow and lymphangiogenesis during the acute versus chronic phases of arthritis in mice

Objective

To develop an in vivo imaging method to assess lymphatic draining function in the K/BxN mouse model of inflammatory arthritis.

Methods

Indocyanine green, a near‐infrared fluorescent dye, was injected intradermally into the footpads of wild‐type mice, mouse limbs were illuminated with an 806‐nm near‐infrared laser, and the movement of indocyanine green from the injection site to the draining popliteal lymph node (LN) was recorded with a CCD camera. Indocyanine green near‐infrared images were analyzed to obtain 5 measures of lymphatic function across time. Images of K/BxN arthritic mice and control nonarthritic littermates were obtained at 1 month of age, when acute joint inflammation commenced, and again at 3 months of age, when joint inflammation became chronic. Lymphangiogenesis in popliteal LNs was assessed by immunochemistry.

Results

Indocyanine green and its transport within lymphatic vessels were readily visualized, and quantitative measures were derived. During the acute phase of arthritis, the lymphatic vessels were dilated, with increased indocyanine green signal intensity and lymphatic pulses, and popliteal LNs became fluorescent quickly. During the chronic phase, new lymphatic vessels were present near the foot. However, the appearance of indocyanine green in lymphatic vessels was delayed. The size and area of popliteal LN lymphatic sinuses progressively increased in the K/BxN mice.

Conclusion

Our findings indicate that indocyanine green near‐infrared lymphatic imaging is a valuable method for assessing the lymphatic draining function in mice with inflammatory arthritis. Indocyanine green–near‐infrared imaging of K/BxN mice identified 2 distinct lymphatic phenotypes during the acute and chronic phase of inflammation. This technique can be used to assess new therapies for lymphatic disorders.

     

An important role of lymphatic vessel activation in limiting acute inflammation

In contrast to the established role of blood vessel remodeling in inflammation, the biologic function of the lymphatic vasculature in acute inflammation has remained less explored. We studied 2 established models of acute cutaneous inflammation, namely, oxazolone-induced delayed-type hypersensitivity reactions and ultraviolet B irradiation, in keratin 14-vascular endothelial growth factor (VEGF)-C and keratin 14-VEGF-D transgenic mice. These mice have an expanded network of cutaneous lymphatic vessels. Transgenic delivery of the lymphangiogenic factors VEGF-C and the VEGFR-3 specific ligand mouse VEGF-D significantly limited acute skin inflammation in both experimental models, with a strong reduction of dermal edema. Expression of VEGFR-3 by lymphatic endothelium was strongly down-regulated at the mRNA and protein level in acutely inflamed skin, and no VEGFR-3 expression was detectable on inflamed blood vessels and dermal macrophages. There was no major change of the inflammatory cell infiltrate or the composition of the inflammatory cytokine milieu in the inflamed skin of VEGF-C or VEGF-D transgenic mice. However, the increased network of lymphatic vessels in these mice significantly enhanced lymphatic drainage from the ear skin. These results provide evidence that specific lymphatic vessel activation limits acute skin inflammation via promotion of lymph flow from the skin and reduction of edema formation.     

The role of the resident intestinal flora in acute and chronic dextran sulfate sodium-induced colitis in mice

OBJECTIVE: There is increasing evidence that the intestinal microflora plays an important role in the pathogenesis of inflammatory bowel disease. In the present study, we examined the role of the resident intestinal flora in our model of dextran sulfate sodium (DSS)-induced acute and chronic colitis in mice. METHODS: Acute colitis was induced in BALB/c mice with 5% DSS in their drinking water for 7 days. Chronic colitis was established after four cycles of feeding 5% DSS for 7 days and water for 10 days. For eliminating intestinal bacteria, mice were injected intraperitoneally with metronidazole and ciprofloxacin. We analysed four parameters: (1) body weight, (2) length of the colon, (3) histological score, and (4) myeloperoxidase activity. RESULTS: In acute DSS colitis treatment with antibiotics led to an improvement of the histological parameters (epithelial damage, P< 0.05; inflammatory infiltrate, P< 0.05) and colon length (P < 0.0028). A significant reduction in granulocyte infiltration was indicated by a 52.6% reduced myeloperoxidase activity in colonic biopsies. By contrast, in chronic colitis, treatment of mice with antibiotics failed to show significant effects. CONCLUSION: In acute DSS-induced colitis bacteria and/or bacterial products play a major role in initiation of inflammation but not in chronic DSS colitis.     

肠系膜淋巴结Th1、Th17细胞在小鼠结肠炎模型发病中作用的研究

背景:大量研究表明细胞因子网络在溃疡性结肠炎(UC)的发病和疾病进程中起关键作用,但相关研究主要集中于肠黏膜免疫细胞方面。目的:探讨肠系膜淋巴结Th1、Th17细胞在模拟人类UC的小鼠DSS结肠炎模型发病中的作用。方法:C57BL/6小鼠饮用5%DSS溶液7 d诱导实验性结肠炎,实验过程中每天评估疾病活动指数(DAI)。于第8 d处死小鼠,ELISA法测定结肠组织IL-1β含量;分离肠系膜淋巴结细胞,以CD3/CD28单抗诱导淋巴细胞活化并以ELISA法测定细胞培养上清液中的Th1、Th17细胞因子含量,流式细胞术检测肠系膜淋巴结F4/80+CD11b+巨噬细胞和CD4+T细胞内Th1、Th17细胞因子表达。结果:结肠炎模型组DAI随实验进程而逐渐增加,于第7 d达峰值。与正常对照组相比,模型组结肠组织IL-1β蛋白表达显著上调(P<0.05),肠系膜淋巴结巨噬细胞浸润增加(P<0.001),淋巴细胞IL-17A分泌水平显著增高(P<0.05),IFN-γ分泌水平亦呈增高趋势(P>0.05),CD4+T细胞内IL-17A、IFN-γ表达显著上调(P<0.05)。结论:肠系膜淋巴结Th1、Th17细胞过度激活可能通过释放效应细胞因子诱导巨噬细胞等浸润、活化,参与介导小鼠DSS结肠炎模型的肠黏膜炎症反应和病理损伤。     

MyD88 signaling in nonhematopoietic cells protects mice against induced colitis by regulating specific EGF receptor ligands

Toll-like receptors (TLRs) trigger intestinal inflammation when the epithelial barrier is breached by physical trauma or pathogenic microbes. Although it has been shown that TLR-mediated signals are ultimately protective in models of acute intestinal inflammation [such as dextran sulfate sodium (DSS)-induced colitis], it is less clear which cells mediate protection. Here we demonstrate that TLR signaling in the nonhematopoietic compartment confers protection in acute DSS-induced colitis. Epithelial cells of MyD88/Trif-deficient mice express diminished levels of the epidermal growth factor receptor (EGFR) ligands amphiregulin (AREG) and epiregulin (EREG), and systemic lipopolysaccharide administration induces their expression in the colon. N-ethyl-N-nitrosourea (ENU)-induced mutations in Adam17 (which is required for AREG and EREG processing) and in Egfr both produce a strong DSS colitis phenotype, and the Adam17 mutation exerts its deleterious effect in the nonhematopoietic compartment. The effect of abrogation of TLR signaling is mitigated by systemic administration of AREG. A TLR→MyD88→AREG/EREG→EGFR signaling pathway is represented in nonhematopoietic cells of the intestinal tract, responds to microbial stimuli once barriers are breached, and mediates protection against DSS-induced colitis.     

Human thioredoxin-1 ameliorates experimental murine colitis in association with suppressed macrophage inhibitory factor production

BACKGROUND & AIMS: Thioredoxin-1 (TRX) is a small multifunctional protein with antioxidative and redox-regulating functions. In this study, we investigated the significance of TRX in patients with inflammatory bowel disease (IBD) and the ability and mechanism to ameliorate experimental colitis. METHODS: Serum TRX and macrophage migration inhibitory factor (MIF) levels were measured in patients with IBD. The effects of TRX were evaluated in a dextran sulfate sodium (DSS)-induced colitis model by comparing TRX-overexpressing transgenic (TRX-TG) and control mice. We further evaluated the effect of recombinant human TRX (rhTRX) administration on DSS-induced colitis and colonic inflammation of interleukin (IL)-10 knockout (IL-10 KO) mice. Colonic inflammation was examined clinically and histologically. Proinflammatory cytokine levels were examined in colonic tissues, and MIF levels were measured in colonic tissues and sera in mice. The effect of TRX on MIF production was also analyzed in vitro. RESULTS: Serum TRX and MIF levels were significantly higher in patients with IBD than normal controls, and TRX levels correlated with disease activity. TRX significantly ameliorated DSS-induced colitis and colonic inflammation of IL-10 KO mice. Increase of tumor necrosis factor-alpha and interferon-gamma in colonic tissues was significantly suppressed in TRX-TG mice compared with wild-type mice. MIF levels in colonic tissues and sera were significantly lower in TRX-TG mice than in wild-type mice, irrespective of DSS administration. Anti-TRX treatment exacerbated DSS-induced colitis. In vitro studies demonstrated that rhTRX suppressed MIF production in human monocyte cells. CONCLUSIONS: TRX might have a potential as a novel therapeutic agent for the treatment of IBD.     

发酵黑麦糠对右旋葡聚糖硫酸钠诱导的小鼠结肠炎的保护作用

溃疡性结肠炎是一种病因和发病机制尚不明确的结肠黏膜和黏膜下层慢性炎症。体内外试实验表明，发酵黑麦糠可抑制幽门螺杆菌(H．pylori)对胃黏膜的黏附作用，从而保护小鼠免受H．pylori感染。目的：明确发酵黑麦糠是否对右旋葡聚糖硫酸钠(DSS)诱导的小鼠结肠炎有保护作用。方法：以3．5％DSS诱导小鼠产生结肠炎，部分小鼠同时加用发酵黑麦糠，观察结肠炎小鼠的临床表现(体重下降情况、直肠出血情况和有无腹泻)和结肠黏膜的组织学改变。结果：DSS 发酵黑麦糠组小鼠结肠炎起病晚、症状轻，在观察期内无一例出现腹泻；组织学检查和评分结果亦显示该组小鼠结肠黏膜炎症较DSS组轻。结论：发酵黑麦糠对DSS诱导的小鼠结肠炎有保护作用，其具体作用机制尚有待进一步明确。     

Silencing LncRNA-DANCR attenuates inflammation and DSS-induced endothelial injury through miR-125b-5p

BackgroundLncRNA-DANCR is involved in inflammation and acts as a major contributor to colon cancer. The effects and mechanism of LncRNA-DANCR were first investigated in a DSS-induced colitis model in vivo and vitro.Material and methodsSprague-Dawley rats were given DSS to induce the colitis model. TNF-α, IL-1β, IL-6 levels and expression of intestinal adhesion proteins ZO-1 and MUC2 in colon tissues and DSS-induced NCM460 cells were measured using corresponding kits. A hematoxylin and eosin (H&E) staining assay was performed to evaluate colon tissue pathology conditions. Protein expression levels in DSS-induced NCM460 cells were evaluated by Western blotting, and cell apoptosis was detected using a TUNEL assay. Gene levels in DSS-induced NCM460 cells were evaluated by PCR. The StarBase online tool was used to predict the LncRNA-DANCR target. The LncRNA-DANCR target was verified using a luciferase reporter assay.ResultsLncRNA-DANCR was up-regulated in DSS-induced groups of rats. TNF-α, IL-1β and IL-6 expression was significantly increased in DSS-induced groups of rats and cells. Zo-1 and MUC2 expression levels were decreased in DSS-induced groups of rats. Silencing LncRNA-DANCR reduced inflammation, cell apoptosis and up-regulated ZO-1, MUC2 and Claudin-1 in DSS-induced cells. MiR-125b-5p was the downstream LncRNA-DANCR target. All LncRNA-DANCR effects in the colitis model were reversed by the miR-125b-5p inhibitor.ConclusionLncRNA-DANCR/miR-125b-5p, which may act as a regulatory axis in inflammation, apoptosis and barrier function dysregulation, can provide an essential reference for the development of new drugs in colitis treatment.     

R-spondin1, a novel intestinotrophic mitogen, ameliorates experimental colitis in mice

BACKGROUND & AIMS: R-spondin 1 (Rspo1) is a novel epithelial mitogen that stimulates the growth of mucosa in both the small and large intestine. METHODS: We investigated the therapeutic potential of Rspo1 in ameliorating experimental colitis induced by dextran sulfate sodium (DSS) or trinitrobenzene sulfonic acid (TNBS) as well as nonsteroidal anti-inflammatory drug-induced colitis in interleukin (IL)-10-deficient mice. RESULTS: Therapeutic administration of recombinant Rspo1 protein reduced the loss of body weight, diarrhea, and rectal bleeding in a mouse model of acute or chronic DSS-induced colitis. Histologic evaluation revealed that Rspo1 improved mucosal integrity in both villus and/or crypt compartments in the small intestine and colon by stimulating crypt cell growth and mucosal regeneration in DSS-treated mice. Moreover, Rspo1 significantly reduced DSS-induced myeloperoxidase activity and inhibited the overproduction of proinflammatory cytokines, including tumor necrosis factor-alpha, IL-1alpha, IL-6, interferon-gamma, and granulocyte-macrophage colony-stimulating factor, in mouse intestinal tissue, indicating that Rspo1 may reduce DSS-induced inflammation by preserving the mucosal barrier function. Likewise, Rspo1 therapy also alleviated TNBS-induced interstitial inflammation and mucosal erosion in the mouse colon. Furthermore, Rspo1 substantially decreased the histopathologic severity of chronic enterocolitis by repairing crypt epithelium and simultaneously suppressing inflammatory infiltration in piroxicam-exposed IL-10(-/-) mice. Endogenous Rspo1 protein was localized to villus epithelium and crypt Paneth cells in mouse small intestine. CONCLUSIONS: Our results show that Rspo1 may be clinically useful in the therapeutic treatment of inflammatory bowel disease by stimulating crypt cell growth, accelerating mucosal regeneration, and restoring intestinal architecture.     

The Role of Zinc and Metallothionein in the Dextran Sulfate Sodium-Induced Colitis Mouse Model

Zinc (Zn) and its binding protein metallothionien (MT) have been proposed to suppress the disease activity in ulcerative colitis. To determine the role of Zn and MT in the dextran sulfate sodium (DSS)-induced model of colitis in mice, a DSS dose-response study was conducted in male C57BL/6 wild-type (MT+/+) and MT-null (MT−/−) mice by supplementing 2%, 3%, and 4% DSS in the drinking water for 6 days. In the intervention study, colitis was induced with 2% DSS, Zn (24 mg/ml as ZnO) was gavaged (0.1 ml) daily, concurrent with DSS administration, and the disease activity index (DAI) was scored daily. Histology, MT levels, and myeloperoxidase (MPO) activity were determined. DAI was increased (P<0.05) by 16% and 21% with 3% and 4% concentrations of DSS, respectively, compared to 2%, evident after 5 days of DSS administration. MPO activity was increased in MT+/+ compared to MT−/− mice and those receiving DSS. Zn administration had a 50% (P<0.05) lower DAI compared to DSS alone. Zn partially prevented the distal colon of MT+/+ by 47% from DSS-induced damage compared to MT−/− mice. MT did not prevent DSS-induced colitis and Zn was partially effective in amelioration of DSS-induced colitis.     

Near-infrared fluorescence imaging using a protease-specific probe for the detection of colon tumors

Background/Aims

Early tumor detection is crucial for the prevention of colon cancer. Near-infrared fluorescence (NIRF) imaging using a target-activatable probe may permit earlier disease detection. Matrix metalloproteinases (MMPs) participate in tumorigenesis and tumor growth. The aim of this study was to determine whether NIRF imaging using an MMP-activatable probe can detect colon tumors at early stages.

Methods

We utilized two murine colon cancer models: a sporadic colon cancer model induced by azoxymethane (AOM), and a colitis-associated cancer model induced by a combination of AOM and dextran sodium sulfate (DSS). Colonic lesions were analyzed by histologic examination, Western blotting, immunohistochemical staining, and NIRF imaging using an MMP-activatable probe.

Results

Multiple variable-sized tumors developed in both models and progressed from adenomas to adenocarcinomas over time. At the early stage of the AOM/DSS model, diffuse inflammation was observed within the tumors. MMP expression increased progressively through normal, inflammation, adenoma, and adenocarcionoma stages. NIRF signal intensities were strongly correlated with each tumor stage from adenoma to adenocarcinoma. NIRF imaging also distinguished tumors from inflamed mucosa.

Conclusions

NIRF imaging using a protease-activatable probe may be a useful tool for early tumor detection. This approach could translate to improve the endoscopic detection of colon tumors, especially in patients with inflammatory bowel disease.     

Amelioration of intestinal colitis by macrophage migration inhibitory factor isolated from intestinal parasites through toll-like receptor 2

In a previous study, we cloned type II MIFs (As-MIF) from Anisakis simplex 3rd stage larva and expressed a recombinant protein that suppressed allergic airway inflammation via regulatory T (CD4(+) CD25(+) Foxp3(+) T; T(reg) )-cell recruitment. In this study, in an effort to evaluate the function of rAs-MIF on another immune disease, we induced intestinal inflammation in mice using dextran sodium sulphate (DSS) with or without the application of rAs-MIF treatment to the mice. As a consequence, weight losses were recovered, and the value of disease activity index (DAI) was reduced by rAs-MIF treatment during the experimental period. The levels of TGF-β and IL-10 in the spleens and mesenteric lymph nodes (MLN) from the rAs-MIF-treated mice were higher, but the levels of IFN-γ, IL-6 and IL-13 were lower than those of the mice treated with DSS but not with rAs-MIF. Additionally, the T(reg) cells observed were greatly increased in the MLNs of the rAs-MIF-treated mice than those of mice not treated with rAs-MIF. The results of our in vitro experiments showed that the elevated IL-10 production induced by rAs-MIF was generated via toll-like receptor 2. In conclusion, rAs-MIF appears to ameliorate DSS-induced colitis and may prove useful as a therapeutic agent for the treatment of intestinal inflammatory disease.     

Intravital imaging of DSS-induced cecal mucosal damage in GFP-transgenic mice using two-photon microscopy

Background

Two-photon laser-scanning microscopy (TPLSM) is a powerful diagnostic tool for real-time, high-resolution structural imaging. However, obtaining high-quality in vivo TPLSM images of intra-abdominal organs remains technically challenging.

Materials and methods

An organ-stabilizing system was applied to high-quality TPLSM imaging. Real-time imaging of visceral organs, such as the liver, spleen, kidney and intestine, of transgenic green fluorescent protein (GFP) mice was performed in vivo using TPLSM. The bacterial translocation model using dextran sodium sulfate (DSS)-induced colitis was also investigated in prepared GFP mice following simple surgery. This allowed the capture of morphological real images using in vivo TPLSM. Immunohistochemical analysis of ZO-1 was performed to support the morphological findings of TPLSM.

Results and conclusions

We established an organ-stabilizing system to evaluate the real-time imaging of visceral organs in actin–GFP transgenic mice using in vivo TPLSM. DSS-induced colitis showed irregularity of crypt architecture, disappearance of crypts, inflammatory cell infiltration and increased rolling of white blood cells along the vasculature. In addition, the intercellular distance of mucosal cells in the crypt and vascular endothelial cells in the intestinal wall was increased in the intestinal mucosa during DSS colitis. In DSS colitis, there was remarkable loss of mucosal and vascular endothelial ZO-1 expression, as could be seen by a decrease in ZO-1 staining. In conclusion, our observations suggested the possibility that our TPLSM imaging system can be used to clarify the pathophysiological changes in various diseases using longitudinal studies of microscopic changes in the same animal over long periods of time.     

Low-dose oral ferrous fumarate aggravated intestinal inflammation in rats with DSS-induced colitis

BACKGROUND: Oral ferrous iron therapy may reinforce intestinal inflammation. One possible mechanism is by catalyzing the production of reactive oxygen species. We studied the effects of low-dose oral ferrous fumarate on intestinal inflammation and plasma redox status in dextran sulfate sodium (DSS)-induced colitis in rats. METHODS: Forty male Wistar rats were divided into 5 groups: no intervention, sham gavage (distilled water), ferrous fumarate, DSS, and ferrous fumarate + DSS. Ferrous fumarate was dissolved in distilled water (0.60 mg Fe/kg per day) and administered by gavage on days 1 to 14. All rats were fed a standard diet. Colitis was induced by 5% DSS in drinking water on days 8 to 14. Rats were killed on day 16. Histologic colitis scores, fecal granulocyte marker protein, plasma malondialdehyde, plasma antioxidant vitamins, and plasma aminothiols were measured. RESULTS: DSS significantly increased histologic colitis scores (P < 0.001) and fecal granulocyte marker protein (P < 0.01). Ferrous fumarate further increased histologic colitis scores (P < 0.01) in DSS-induced colitis. DSS + ferrous fumarate decreased plasma vitamin A compared with controls (P < 0.01). Otherwise, no changes were seen in plasma malondialdehyde, plasma antioxidant vitamins, or plasma aminothiols. CONCLUSION: Low-dose oral ferrous iron enhanced intestinal inflammation in DSS-induced colitis in rats.     

Constitutive androstane receptor and pregnane X receptor cooperatively ameliorate DSS-induced colitis

Background

Nuclear receptor pregnane X receptor (PXR) was shown to be protective in case of dextran sulfate sodium (DSS)-induced colitis. Constitutive androstane receptor (CAR) belongs to the same nuclear receptor subfamily with PXR. The roles of both receptors in DSS-induced colitis were evaluated.

Dextran Sulfate Sodium-Induced Colitis Is Associated with Enhanced Low Molecular Mass Polypeptide 2 (LMP2) Expression and Is Attenuated in LMP2 Knockout Mice

Low molecular mass polypeptide 2 (LMP2) is an inducible proteasome subunit. Our goals were to examine LMP2 expression in mice with dextran sulfate sodium (DSS)-induced colitis and to evaluate colitis in LMP2 knockout (LMP2-/-) mice. Mice were given 2.5% DSS in the drinking water. On day 0, 2, 4, or 6 after DSS treatment, LMP2 expression was determined in the distal colon by western blot and immunohistochemistry. Parameters of colitis were measured in LMP2-/- mice or wild-type mice. LMP2 expression was enhanced in the colon of DSS-treated mice at all time points. Symptoms of DSS-induced colitis were always lower in LMP2-/- mice. Normalized histology scores and colonic IL-1ss levels increased over the 6-day study period in wild-type mice. These parameters were significantly reduced in LMP2-/- mice that consumed DSS for 6 days. Enhanced LMP2 expression contributes to the pathogenesis of DSS-induced colitis in mice.     

Inhibition of neutrophil elastase prevents the development of murine dextran sulfate sodium-induced colitis

Background Neutrophil elastase (NE) is a major secretory product from activated neutrophils and a major contributor to tissue destruction. However, little is known about the pathogenic contribution of NE to ulcerative colitis (UC). This study was designed to investigate the contribution of NE by measuring NE activity in plasma and colonic mucosal tissue from UC patients and a murine acute colitis model, and to elucidate the therapeutic effect of the NE-specific inhibitor ONO-5046. Methods The NE enzyme activities in plasma and colonic mucosal tissue from UC patients were directly measured using an enzyme–substrate reaction. Acute colitis was induced in mice by administration of 1.5% dextran sulfate sodium (DSS) for 5 days. DSS-induced colitis mice were then treated with ONO-5046 (50 mg/kg body weight) intraperitoneally twice a day. Results In UC patients, the NE enzyme activity was significantly elevated in both the plasma and colonic mucosal tissue compared with healthy controls. In DSS-induced colitis mice, the NE enzyme activity increased in parallel with the disease development. ONO-5046 showed therapeutic effects in DSS-treated mice by significantly reducing weight loss and histological score. ONO-5046 suppressed the NE enzyme activities in both plasma and culture supernatant of colonic mucosa from DSS-induced colitis mice. Conclusions ONO-5046, a specific NE inhibitor, prevented the development of DSS-induced colitis in mice. NE therefore represents a promising target for the treatment of UC patients.