The immunomodulatory effects of adipose‐derived mesenchymal stem cells and mesenchymal stem cells‐conditioned medium in chronic colitis

Inflammatory bowel disease (IBD) as a chronic recurrent disorder is characterized by mucosal immune response dysregulation, which is more prevalent in the youth. Adipose‐derived mesenchymal stem cells (ADMSCs) are the multipotent cells that can be effective in immune response regulation via cell–cell interaction and their secretions. In this study, the effects of ADMSCs and mesenchymal stem cell‐conditioned medium (MSC‐CM) were evaluated on dextran sulfate sodium (DSS)‐induced colitis in mice. Chronic colitis was induced in female C57BL/6 mice using 2% DSS in drinking water for three cycles; there were 4 days of DSS‐water administration that was followed by 7 days of DSS‐free water, in a cycle. ADMSCs, 10⁶ cells per mouse, were injected intraperitoneally (IP), whereas the MSC‐CM injection was also performed six times from the last day of DSS in Cycle 1. Clinical symptoms were recorded daily. The colon pathological changes, cytokine levels, and regulatory T (Treg) cell percentages were then analyzed. After receiving ADMSCs and MSC‐CM in colitis mice, the clinical symptoms and disease activity index were improved and the survival rate was increased. The histopathological examination also showed tissue healing in comparison with the nontreated group. In addition, the increased level of transforming growth factor beta, increased percentage of Treg cells, increased level of interleukin (IL)‐10, and decreased level of IL‐17 were observed after the treatment. This study showed the regulatory effects of ADMSCs and MSC‐CM on inflammatory responses. Therefore, the use of ADMSCs and MSC‐CM can be introduced as a new and effective therapeutic approach for patients with colitis.     

鼠衣原体改善DSS诱导的小鼠溃疡性结肠炎的作用研究

【目的】探讨鼠衣原体(Chlamydia muridarum)对小鼠溃疡性结肠炎的作用。【方法】取15只雌性C57BL/6J小鼠随机分为3组,每组5只动物,分别为空白对照组(Control)、肠炎模型组(DSS)、实验组(CM+DSS)。选取CM+DSS组小鼠予以2×10~5 IFU的鼠衣原体灌胃处理,并在其感染后第29天开始,给予DSS组和CM+DSS组的小鼠2%DSS饮水,持续5d,每天监测小鼠体重和肠炎疾病评分,实验结束后检测小鼠结肠长度和结肠组织炎性改变。【结果】肠炎模型组的小鼠均表现出典型的肠炎症状(包括体重减轻、肠炎疾病评分、结肠长度和组织炎性改变);而经鼠衣原体预处理的小鼠(CM+DSS组)肠炎症状显著减轻,表现在肠炎疾病评分降低,体重和结肠长度有所恢复,肠组织炎性损伤减轻。【结论】鼠衣原体对DSS诱导的小鼠溃疡性结肠炎具有改善作用。     

氯化两面针碱对小鼠溃疡性结肠炎的干预作用及其机制*

目的:探讨氯化两面针碱(NC)通过靶向miR-31对葡聚糖硫酸钠(DSS)诱发小鼠结肠炎的保护作用及其机制。方法:用1%DSS诱发小鼠溃疡性结肠炎(UC)。30只雄性C57BL/6小鼠随机分为正常对照组(Control)(n=7),DSS组(n=8),DSS+NC组(7.27 mg/kg)(n=8)和NC组(n=7),饮水给予DSS,灌胃给予氯化两面针碱。造模周期为3周,分别为Control组和NC组每天饮用无菌水,DSS组和DSS+NC组第一周饮用1% DSS水,第2周正常饮水,第3周1% DSS水。造模最后一周给予Control组和DSS组小鼠0.5% 羧甲基纤维素钠(CMC-Na)灌胃,DSS+NC组和NC组给予NC灌胃。造模完成后,观察小鼠结肠炎相关的疾病活动指数(DAI),HE染色进行结肠组织病理评分,qPCR检测小鼠结肠组织miR-31的表达水平,Western blot检测小鼠结肠组织炎症蛋白NF-κB和COX-2的表达情况。结果:①与DSS组相比,DSS+NC组的 DAI 显著降低(P＜0.01),结肠病理损伤明显改善;②与Control组相比,DSS组小鼠结肠组织miR-31表达显著升高(P＜0.01),DSS+NC组miR-31的表达水平显著低于DSS组(P＜0.05);③与DSS组相比,DSS+NC组中的炎症蛋白NF-κB和COX-2表达水平显著下降(P＜0.05)。结论:氯化两面针碱对DSS诱导的小鼠溃疡性结肠炎有明显的治疗作用,其抗炎机制与下调miR-31的表达有关。     

Therapeutic effects of lentinan on inflammatory bowel disease and colitis‐associated cancer

In this study, we investigated the therapeutic potential of lentinan in mouse models of inflammatory bowel disease (IBD) and colitis‐associated cancer (CAC). Lentinan decreased the disease activity index and macroscopic and microscopic colon tissue damage in dextran sulphate sodium (DSS)‐induced or TNBS‐induced models of colitis. High‐dose lentinan was more effective than salicylazosulfapyridine in the mouse models of colitis. Lentinan decreased the number of tumours, inflammatory cell infiltration, atypical hyperplasia and nuclear atypia in azoxymethane/DSS‐induced CAC model. It also decreased the expression of pro‐inflammatory cytokines, such as IL‐13 and CD30L, in IBD and CAC model mice possibly by inhibiting Toll‐like receptor 4 (TLR4)/NF‐κB signalling and the expression of colon cancer markers, such as carcinoembryonic antigen, cytokeratin 8, CK18 and p53, in CAC model mice. In addition, lentinan restored the intestinal bacterial microbiotal community structure in IBD model mice. Thus, it shows therapeutic potential in IBD and CAC model mice possibly by inhibiting TLR4/NF‐κB signalling‐mediated inflammatory responses and disruption of the intestinal microbiotal structure.     

RIP3 deficiency exacerbates inflammation in dextran sodium sulfate‐induced ulcerative colitis mice model

Ulcerative colitis (UC) is a chronic intestinal inflammatory disease. The receptor‐interacting protein kinase 3 (RIP3) was reported to be involved in many inflammatory disease. However, the mechanism of RIP3 in the pathogenesis of UC is still unclear. To investigate the effects and possible mechanism of RIP3 in UC pathogenesis, RIP3‐/‐ mice was used in dextran sulfate sodium (DSS)‐induced colitis model. It was found that by DSS‐induced colitis, RIP3‐/‐ mice showed significantly enhanced colitis symptoms, including increased weight loss, colon shortening, and colonic mucosa damage and severity, but decreased production of interleukin 6 and interleukin 1β. The results showed that RIP3 deficiency could not ameliorate but exacerbate the severity of colitis. On the mechanism, it was found that messenger RNA expressions of several repair‐associated cytokines including interleukin 6, interleukin 22, cyclooxygenase 2, epithelial growth factor receptor ligand Epiregulin and matrix metalloproteinase 10 were siginificant decreased in RIP3‐/‐ mice. Thus, RIP3‐/‐ mice exhibited an impaired tissue repair in response to DSS. In a conclusion, RIP3 deficiency exerted detrimental effects in DSS induced colitis partially because of the impaired repair‐associated cytokines expression.     

过表达miR-31对结肠炎模型小鼠TLR4/NF-κB信号通路及凋亡蛋白的调控

目的: 探讨miR-31对DSS诱发结肠炎小鼠TLR4/NF-κB信号通路和凋亡相关蛋白的影响。方法: ①小鼠结肠炎实验:用1%葡聚糖硫酸钠(DSS)诱发小鼠溃疡性结肠炎(UC)。14只FVB非转基因小鼠随机分为control组(n=6),DSS组(n=8),16只FVB miR-31转基因小鼠随机分为miR-31过表达组(n=8),miR-31过表达+DSS 组(n=8),DSS溶于水后通过饮水给予小鼠。DSS组和miR-31+DSS组第一周饮用1%DSS水,第二周饮用正常无菌水,第三周饮用1%DSS水,如此5周后造模完成,之后留取小鼠的结肠组织,通过Western blot和IHC检测小鼠结肠组织NF-κB p65、TLR4、Bax、Bcl-2蛋白的表达;TUNEL检测小鼠结肠组织细胞凋亡。②细胞培养实验:在人结肠上皮细胞系HCT 116细胞中通过脂质体转染的方法转染miR-31 mimic和inhibitor,使miR-31过表达或敲低,每组均进行三次重复,48 h后收取细胞,通过Western blot检测NF-κB p65、TLR4蛋白的表达。结果: ①动物实验中,与control组相比,小鼠结肠组织中DSS组和miR-31过表达组NF-κB p65、TLR4蛋白表达水平和凋亡细胞指数均显著升高(P＜0.05或P＜0.01),Bcl-2/Bax比值显著降低(P＜0.05或P＜0.01);且与DSS组相比,miR-31+DSS组NF-κB p65、TLR4蛋白表达水平和凋亡细胞指数也显著升高(P＜0.01),Bcl-2/Bax比值显著降低(P＜0.01)。②细胞实验中,与control组相比, HCT 116细胞过表达miR-31组的NF-κB p65、TLR4蛋白表达水平均显著升高(P＜0.05或P＜0.01),敲低miR-31组的NF-κB p65、TLR4蛋白表达水平下降(P＜0.05)。结论: miR-31通过促进TLR4/NF-κB信号通路和介导肠上皮细胞凋亡促进结肠炎的发展。     

IL‐35 recombinant protein reverses inflammatory bowel disease and psoriasis through regulation of inflammatory cytokines and immune cells

Interleukin‐35 (IL‐35), a member of the IL‐12 family, functions as a new anti‐inflammatory factor involved in arthritis, psoriasis, inflammatory bowel disease (IBD) and other immune diseases. Although IL‐35 can significantly prevent the development of inflammation in many diseases, there have been no early studies accounting for the role of IL‐35 recombinant protein in IBD and psoriasis. In this study, we assessed the therapeutic potential of IL‐35 recombinant protein in three well‐known mouse models: the dextransulfate sodium (DSS)‐induced colitis mouse model, the keratin14 (K14)‐vascular endothelial growth factor A (VEGF‐A)‐transgenic (Tg) psoriasis mouse model and the imiquimod (IMQ)‐induced psoriasis mouse model. Our results indicated that IL‐35 recombinant protein can slow down the pathologic process in DSS‐induced acute colitis mouse model by decreasing the infiltrations of macrophages, CD4⁺T and CD8⁺T cells and by promoting the infiltration of Treg cells. Further analysis demonstrated that IL‐35 recombinant protein may regulate inflammation through promoting the secretion of IL‐10 and inhibiting the expression of pro‐inflammatory cytokines such as IL‐6, TNF‐α and IL‐17 in acute colitis model. In addition, lower dose of IL‐35 recombinant protein could achieve long‐term treatment effects as TNF‐α monoclonal antibody did in the psoriasis mouse. In summary, the remarkable therapeutic effects of IL‐35 recombinant protein in acute colitis and psoriasis mouse models indicated that IL‐35 recombinant protein had a variety of anti‐inflammatory effects and was expected to become an effective candidate drug for the treatment of inflammatory diseases.     

Investigating Intestinal Inflammation in DSS-induced Model of IBD

Inflammatory bowel disease (IBD) encompasses a range of intestinal pathologies, the most common of which are ulcerative colitis (UC) and Crohn''s Disease (CD). Both UC and CD, when present in the colon, generate a similar symptom profile which can include diarrhea, rectal bleeding, abdominal pain, and weight loss.¹ Although the pathogenesis of IBD remains unknown, it is described as a multifactorial disease that involves both genetic and environmental components.²There are numerous and variable animal models of colonic inflammation that resemble several features of IBD. Animal models of colitis range from those arising spontaneously in susceptible strains of certain species to those requiring administration of specific concentrations of colitis-inducing chemicals, such as dextran sulphate sodium (DSS). Chemical-induced models of gut inflammation are the most commonly used and best described models of IBD. Administration of DSS in drinking water produces acute or chronic colitis depending on the administration protocol.³ Animals given DSS exhibit weight loss and signs of loose stool or diarrhea, sometimes with evidence of rectal bleeding.^4,5 Here, we describe the methods by which colitis development and the resulting inflammatory response can be characterized following administration of DSS. These methods include histological analysis of hematoxylin/eosin stained colon sections, measurement of pro-inflammatory cytokines, and determination of myeloperoxidase (MPO) activity, which can be used as a surrogate marker of inflammation.⁶The extent of the inflammatory response in disease state can be assessed by the presence of clinical symptoms or by alteration in histology in mucosal tissue. Colonic histological damage is assessed by using a scoring system that considers loss of crypt architecture, inflammatory cell infiltration, muscle thickening, goblet cell depletion, and crypt abscess.⁷ Quantitatively, levels of pro-inflammatory cytokines with acute inflammatory properties, such as interleukin (IL)-1β, IL-6 and tumour necrosis factor (TNF)-α,can be determined using conventional ELISA methods. In addition, MPO activity can be measured using a colorimetric assay and used as an index of inflammation.⁸In experimental colitis, disease severity is often correlated with an increase in MPO activity and higher levels of pro-inflammatory cytokines. Colitis severity and inflammation-associated damage can be assessed by examining stool consistency and bleeding, in addition to assessing the histopathological state of the intestine using hematoxylin/eosin stained colonic tissue sections. Colonic tissue fragments can be used to determine MPO activity and cytokine production. Taken together, these measures can be used to evaluate the intestinal inflammatory response in animal models of experimental colitis.     

Attenuation by dietary taurine of dextran sulfate sodium-induced colitis in mice and of THP-1-induced damage to intestinal Caco-2 cell monolayers

The effects of dietary taurine on the experimental colitis induced by dextran sulfate sodium (DSS) in mice were evaluated. C57BL/6 female mice were given 3% DSS in drinking water for 5 d to induce acute colitis. Taurine at 2% was added to the drinking water 5 d before and during the DSS-treatment to investigate its preventive effect. Taurine supplementation significantly attenuated the weight decrease, diarrhea severity, colon shortening, and the increase in the colonic tissue myeloperoxidase activity induced by DSS. Taurine also significantly inhibited the increase in the expression of a pro-inflammatory chemokine, macrophage inflammatory protein 2 (MIP-2), but not of interleukin (IL)-1beta or tumor necrosis factor (TNF)-alpha mRNA. Furthermore, taurine significantly protected the intestinal Caco-2 cell monolayers from the damage by macrophage-like THP-1 cells in an in vitro coculture system. These results suggest that taurine prevented DSS-induced colitis partly in association with (1) its inhibitory effects on the secretion of MIP-2 from the intestinal epithelial cells and on the infiltration of such inflammatory cells as neutrophils and (2) its cytoprotective functions on the epithelial barrier from the direct toxicity of DSS and from the inflammatory cell-induced injury.     

Dietary astaxanthin inhibits colitis and colitis-associated colon carcinogenesis in mice via modulation of the inflammatory cytokines

Astaxanthin (AX) is one of the marine carotenoid pigments, which possess powerful biological antioxidant, anti-inflammatory and anti-cancer properties. The purpose of this study is to investigate possible inhibitory effect of AX against inflammation-related mouse colon carcinogenesis and dextran sulfate sodium (DSS)-induced colitis in male ICR mice. We conducted two different experiments. In the first experiment, we evaluated the effects of AX at three dose levels, 50, 100 and 200 ppm in diet, on colitis-associated colon carcinogenesis induced by azoxymethane (AOM)/DSS in mice. In the second, the effects of the AX (100 and 200 ppm) in diet on DSS-induced colitis were determined. We found that dietary AX significantly inhibited the occurrence of colonic mucosal ulcers, dysplastic crypts, and colonic adenocarcinoma at week 20. AX-feeding suppressed expression of inflammatory cytokines, including nuclear factor (NF)-κB, tumor necrosis factor (TNF)-α and interleukin (IL)-1β, inhibited proliferation, and induced apoptosis in the colonic adenocarcinomas. Feeding with 200 ppm AX, but not 100 ppm, significantly inhibited the development of DSS-induced colitis. AX feeding (200 ppm in diet) also lowered the protein expression of NF-κB, and the mRNA expression of inflammatory cytokines, including IL-1β, IL-6, and cyclooxygenase (COX)-2. Our results suggest that the dietary AX suppresses the colitis and colitis-related colon carcinogenesis in mice, partly through inhibition of the expression of inflammatory cytokine and proliferation. Our findings suggest that AX is one of the candidates for prevention of colitis and inflammation-associated colon carcinogenesis in humans.     

Metformin protects against intestinal barrier dysfunction via AMPKα1‐dependent inhibition of JNK signalling activation

Disruption of the intestinal epithelial barrier, that involves the activation of C‐Jun N‐terminal kinase (JNK), contributes to initiate and accelerate inflammation in inflammatory bowel disease. Metformin has unexpected beneficial effects other than glucose‐lowering effects. Here, we provided evidence that metformin can protect against intestinal barrier dysfunction in colitis. We showed that metformin alleviated dextran sodium sulphate (DSS)‐induced decreases in transepithelial electrical resistance, FITC‐dextran hyperpermeability, loss of the tight junction (TJ) proteins occludin and ZO‐1 and bacterial translocation in Caco‐2 cell monolayers or in colitis mice models. Metformin also improved TJ proteins expression in ulcerative colitis patients with type 2 diabetes mellitus. We found that metformin ameliorated the induction of colitis and reduced the levels of pro‐inflammatory cytokines IL‐6, TNF‐a and IL‐1β. In addition, metformin suppressed DSS‐induced JNK activation, an effect dependent on AMP‐activated protein kinase α1 (AMPKα1) activation. Consistent with this finding, metformin could not maintain the barrier function of AMPKα1‐silenced cell monolayers after DSS administration. These findings highlight metformin protects against intestinal barrier dysfunction. The potential mechanism may involve in the inhibition of JNK activation via an AMPKα1‐dependent signalling pathway.     

UNC5B receptor deletion exacerbates DSS‐induced colitis in mice by increasing epithelial cell apoptosis

The netrin-1 administration or overexpression is known to protect colon from acute colitis. However, the receptor that mediates netrin-1 protective activities in the colon during colitis remains unknown. We tested the hypothesis that UNC5B receptor is a critical mediator of protective function of netrin-1 in dextran sodium sulfate (DSS)-induced colitis using mice with partial deletion of UNC5B receptor. DSS colitis was performed in mice with partial genetic UNC5B deficiency (UNC5B^+/− mice) or wild-type mice to examine the role of endogenous UNC5B. These studies were supported by in vitro models of DSS-induced apoptosis in human colon epithelial cells. WT mice developed colitis in response to DSS feeding as indicated by reduction in bw, reduction in colon length and increase in colon weight. These changes were exacerbated in heterozygous UNC5B knockout mice treated with DSS. Periodic Acid-Schiff stained section shows damages in colon epithelium and mononuclear cell infiltration in WT mice, which was further increased in UNC5B heterozygous knockout mice. This was associated with large increase in inflammatory mediators such as cytokine and chemokine expression and extensive apoptosis of epithelial cells in heterozygous knockout mice as compared to WT mice. Overexpression of UNC5B human colon epithelial cells suppressed DSS-induced apoptosis and caspase-3 activity. Moreover, DSS induced large amount of netrin-1 and shRNA mediated knockdown of netrin-1 induction exacerbated DSS-induced epithelial cell apoptosis. Our results suggest that UNC5B is a critical mediator of cell survival in response to stress in colon.     

Overexpression of GATA-3 in T Cells Accelerates Dextran Sulfate Sodium-Induced Colitis

Ulcerative colitis (UC) is an inflammatory bowel disease, and its pathogenesis includes genetic, environmental, and immunological factors, such as T helper cells and their secreted cytokines. T helper cells are classified as Th1, Th2, and Th17 cells. However, it is unclear which T helper cells are important in UC. Dextran sulfate sodium (DSS)-induced colitis is a commonly used model of UC. In this study, we induced DSS colitis in Th1 dominant (T-bet transgenic (Tg)) mice, Th2 dominant (GATA-3 Tg) mice, and Th17 dominant (RORγt Tg) mice to elucidate the roles of T helper cell in DSS colitis. The results showed that GATA-3 Tg mice developed the most severe DSS colitis compared with the other groups. GATA-3 Tg mice showed a significant decreased in weight from day 1 to day 7, and an increased high score for the disease activity index compared with the other groups. Furthermore, GATA-3 Tg mice developed many ulcers in the colon, and many neutrophils and macrophages were detected on day 4 after DSS treatment. Measurement of GATA-3-induced cytokines demonstrated that IL-13 was highly expressed in the colon from DSS-induced GATA-3 Tg mice. In conclusion, GATA-3 overexpression in T-cells and IL-13 might play important roles in the development of DSS colitis.     

Anti‐inflammatory effects of eriocitrin against the dextran sulfate sodium–induced experimental colitis in murine model

Inflammatory bowel disease (IBD) is a continual ailment condition which engrosses the entire alimentary canal. The IBD can be primarily distinguished into two forms, ulcerative colitis, and Crohn's disease. The major symptoms of IBD include pustules or abscesses, severe abdominal pain, diarrhea, fistula, and stenosis, which may directly affect the patient's quality of life. A variety of mediators can stimulate the circumstances of IBD, some examples include infections by microbes such as bacteria, perturbation of the immune system and the surrounding environment of the intestines. Severe colitis was stimulated in the experimental animals through administering 4% dextran sulfate sodium (DSS) which is mixed in water ad libitum for 6 days. Eriocitrin (30 mg/kg) was then administered to the experimental animals followed by the induction of severe colitis to evaluate the therapeutic prospective of eriocitrin against the colon inflammation stimulated by DSS. In this study, eriocitrin (30 mg/kg) demonstrated significant (P < .05) attenuation activity against the DSS‐stimulated severe colitis in experimental animals. Eriocitrin counteracted all of the clinical deleterious effects induced by DSS, such as body‐weight loss, colon shortening, histopathological injury, accretion of infiltrated inflammatory cells at the inflamed region and the secretion of inflammatory cytokines. The results clearly showed that eriocitrin effectively attenuated DSS‐induced acute colitis in experimental animals.     

Amelioration of dextran sulfate sodium-induced colitis in mice by oral administration of beta-caryophyllene, a sesquiterpene

beta-Caryophyllene (BCP), a naturally occurring plant sesquiterpene, was examined for anti-inflammatory activity in a mouse model of experimental colitis induced by dextran sulfate sodium (DSS). Colitis was induced by exposing male BALB/c mice to 5% DSS in drinking water for 7 days. BCP in doses of 30 and 300 mg/kg was administered orally once a day, beginning concurrently with exposure to DSS. The body weight and colon length were measured, and histological damage and myeloperoxidase (MPO) activity as well as inflammatory cytokines were assessed in both serum and colonic tissue after 7 days of treatment with DSS. The DSS treatment damaged the colonic tissue, increased MPO activity and inflammatory cytokines, lowered the body weight, and shortened the length of the colon. Oral administration of BCP at 300 mg/kg significantly suppressed the shortening of colon length and slightly offset the loss of body weight. BCP treatment (300 mg/kg) also significantly reduced the inflammation of colon and reversed the increase in MPO activity that had been induced by exposure to DSS. Further, BCP significantly suppressed the serum level of IL-6 protein (a 55% reduction) as well as the level of IL-6 mRNA in the tissue. These results demonstrate that BCP ameliorates DSS-induced experimental colitis, and may be useful in the prevention and treatment of colitis.     

Infection with a helminth parasite prevents experimental colitis via a macrophage-mediated mechanism

The propensity of a range of parasitic helminths to stimulate a Th2 or regulatory cell-biased response has been proposed to reduce the severity of experimental inflammatory bowel disease. We examined whether infection with Schistosoma mansoni, a trematode parasite, altered the susceptibility of mice to colitis induced by dextran sodium sulfate (DSS). Mice infected with schistosome worms were refractory to DSS-induced colitis. Egg-laying schistosome infections or injection of eggs did not render mice resistant to colitis induced by DSS. Schistosome worm infections prevent colitis by a novel mechanism dependent on macrophages, and not by simple modulation of Th2 responses, or via induction of regulatory CD4+ or CD25+ cells, IL-10, or TGF-beta. Infected mice had marked infiltration of macrophages (F4/80+CD11b+CD11c(-)) into the colon lamina propria and protection from DSS-induced colitis was shown to be macrophage dependent. Resistance from colitis was not due to alternatively activated macrophages. Transfer of colon lamina propria F4/80+ macrophages isolated from worm-infected mice induced significant protection from colitis in recipient mice treated with DSS. Therefore, we propose a new mechanism whereby a parasitic worm suppresses DSS-induced colitis via a novel colon-infiltrating macrophage population.     

Neutralization of pro‐inflammatory monocytes by targeting TLR2 dimerization ameliorates colitis

Monocytes have emerged as critical driving force of acute inflammation. Here, we show that inhibition of Toll‐like receptor 2(TLR2) dimerization by a TLR2 transmembrane peptide (TLR2‐p) ameliorated DSS‐induced colitis by interfering specifically with the activation of Ly6C⁺ monocytes without affecting their recruitment to the colon. We report that TLR2‐p directly interacts with TLR2 within the membrane, leading to inhibition of TLR2–TLR6/1 assembly induced by natural ligands. This was associated with decreased levels of extracellular signal‐regulated kinases (ERK) signaling and reduced secretion of pro‐inflammatory cytokines, such as interleukin (IL)‐6, IL‐23, IL‐12, and IL‐1β. Altogether, our study provides insights into the essential role of TLR2 dimerization in the activation of pathogenic pro‐inflammatory Ly6C^hi monocytes and suggests that inhibition of this aggregation by TLR2‐p might have therapeutic potential in the treatment of acute gut inflammation.     

敲减突触结合蛋白 1 通过抑制 IL-6/STAT3 信号通路改善结肠炎病变

突触结合蛋白 1 (synaptotagmin 1,Syt1)属于突触结合蛋白家族一员,在神经递质囊泡转运和胞吐中发挥作用。Syt1 在肠道上皮中有表达,但其在结肠炎中的生物学功能尚不明确。本工作以 Syt1 转基因小鼠结合葡聚糖硫酸钠(dextran sodium sulfate,DSS)诱导型溃疡性结肠炎模型,通过 qRT-PCR、免疫染色及 Western 印迹检测 Syt1 在生理状态及肠炎状态下在结肠中表达的动态变化;采用 H&E 染色、免疫染色、Western 印迹等方法,观察 Syt1 在结肠炎的炎症反应及肠道上皮再生修复中的作用。结果显示:正常野生小鼠的结肠上皮及结直肠癌患者癌旁组织的肠上皮细胞中均有较高水平的 Syt1 表达;DSS 处理使 Syt1 在结肠中表达显著升高 (P<0.01)。DSS 诱导小鼠肠炎模型中,相较于对照组,Syt1 敲减小鼠体重降低情况、结肠炎性红肿和长度缩短等均显著减轻 (P<0.05),而再生隐窝数量则增多、Ki67 增殖细胞也增多(P<0.01);结肠组织中的 CD45 免疫细胞、F4/80 巨噬细胞浸润减少 (P<0.001),炎症性肠病相关的促炎因子 IL-1β、IL-6 和 TNFα 分泌也减少 (P<0.05)。免疫组化及Western 印迹结果进一步显示,Syt1 敲减小鼠中,IL-6 和 p-STAT3 表达显著下调(P<0.05)。以上研究结果表明,敲减 Syt1 可能通过抑制 IL-6/STAT3 信号通路改善结肠炎病变程度。     

Antiinflammatory Effect of Phytosterols in Experimental Murine Colitis Model: Prevention,Induction, Remission Study

Phytosterols, besides hypocholesterolemic effect, present anti-inflammatory properties. Little information is available about their efficacy in Inflammatory Bowel Disease (IBD). Therefore, we have evaluated the effect of a mixture of phytosterols on prevention/induction/remission in a murine experimental model of colitis. Phytosterols were administered x os before, during and after colitis induction with Dextran Sodium Sulfate (DSS) in mice. Disease Activity Index (DAI), colon length, histopathology score, ¹⁸F-FDG microPET, oxidative stress in the intestinal tissue (ileum and colon) and gallbladder ileum and colon spontaneous and carbachol (CCh) induced motility, plasma lipids and plasma, liver and biliary bile acids (BA) were evaluated. A similar longitudinal study was performed in a DSS colitis control group. Mice treated with DSS developed severe colitis as shown by DAI, colon length, histopathology score, ¹⁸F-FDG microPET, oxidative stress. Both spontaneous and induced ileal and colonic motility were severely disturbed. The same was observed with gallbladder. DSS colitis resulted in an increase in plasma cholesterol, and a modification of the BA pattern. Phytosterols feeding did not prevent colitis onset but significantly reduced the severity of the disease and improved clinical and histological remission. It had strong antioxidant effects, almost restored colon, ileal and gallbladder motility. Plasmatic levels of cholesterol were also reduced. DSS induced a modification in the BA pattern consistent with an increase in the intestinal BA deconjugating bacteria, prevented by phytosterols. Phytosterols seem a potential nutraceutical tool for gastrointestinal inflammatory diseases, combining metabolic systematic and local anti-inflammatory effects.