Central effects of selective NK1 and NK3 tachykinin receptor agonists on two models of experimentally-induced colitis in rats

Peripheral tachykinins (TKs) are believed to play a role in the pathogenesis of inflammatory bowel diseases (IBD). In this study we investigated changes induced by central administration of two natural TK receptor agonists, NK(1) (PG-SPI) and NK(3) (PG-KII), on trinitrobenzene sulphonic acid (TNBS)- and dextran sodium sulphate (DSS)-induced experimental colitis in rats. Colitis was induced by instilling a single intracolonic dose of TNBS 50 mgkg(-1) (0.5 ml in 50% ethanol) or by oral administration of 5% DSS for 7 days. Each group of rats was intracerebroventricularly injected daily with PG-SPI and PG-KII (0.5, 5, and 50 microgkg(-1)). On day 3, TNBS-treated animals were killed and the severity of gut inflammation was evaluated by measuring myeloperoxidase (MPO) activity, interleukin-1beta (IL-1beta) production and by scoring macroscopic and histologic colonic damage. DSS-treated animals were checked daily for the length of survival and for stool consistency and faecal blood. In the TNBS group, PG-SPI and PG-KII increased scores for the severity of colonic damage, stimulated the production of IL-1beta and increased granulocyte infiltration into the colon (MPO activity). In the DSS group, PG-SPI and PG-KII decreased the percentage of surviving animals, and increased the number of rats that developed loose stools and blood in the faeces and the MPO activity. These results indicate that centrally injected NK(1) and NK(3) tachykinin receptor agonists play a proinflammatory role in experimentally-induced colitis in rats.     

Chemically induced mouse models of intestinal inflammation

Animal models of intestinal inflammation are indispensable for our understanding of the pathogenesis of Crohn disease and ulcerative colitis, the two major forms of inflammatory bowel disease in humans. Here, we provide protocols for establishing murine 2,4,6-trinitro benzene sulfonic acid (TNBS)-, oxazolone- and both acute and chronic dextran sodium sulfate (DSS) colitis, the most widely used chemically induced models of intestinal inflammation. In the former two models, colitis is induced by intrarectal administration of the covalently reactive reagents TNBS/oxazolone, which are believed to induce a T-cell-mediated response against hapten-modified autologous proteins/luminal antigens. In the DSS model, mice are subjected several days to drinking water supplemented with DSS, which seems to be directly toxic to colonic epithelial cells of the basal crypts. The procedures for the hapten models of colitis and acute DSS colitis can be accomplished in about 2 weeks but the protocol for chronic DSS colitis takes about 2 months.     

Enteric neural pathways mediate the anti-inflammatory actions of glucagon-like peptide 2

Glucagon-like peptide-2 (GLP-2) is an important regulator of nutritional absorptive capacity with anti-inflammatory actions. We hypothesized that GLP-2 reduces intestinal mucosal inflammation by activation of vasoactive intestinal polypeptide (VIP) neurons of the submucosal plexus. Ileitis or colitis was induced in rats by injection of trinitrobenzene sulfonic acid (TNBS), or colitis was induced by administration of dextran sodium sulfate (DSS) in drinking water. Subsets of animals received (1-33)-GLP-2 (50 mug/kg sc bid) either immediately or 2 days after the establishment of inflammation and were followed for 3-5 days. The involvement of VIP neurons was assessed by concomitant administration of GLP-2 and the VIP antagonist [Lys(1)-Pro(2,5)-Arg(3,4)-Tyr(6)]VIP and by immunohistochemical labeling of GLP-2-activated neurons. In all models, GLP-2 treatment, whether given immediately or delayed until inflammation was established, resulted in significant improvements in animal weights, mucosal inflammation indices (myeloperoxidase levels, histological mucosal scores), and reduced levels of inflammatory cytokines (IFN-gamma, TNF-alpha, IL-1beta) and inducible nitric oxide synthase, with increased levels of IL-10 in TNBS ileitis and DSS colitis. Reduced rates of crypt cell proliferation and of apoptosis within crypts in inflamed tissues were also noted with GLP-2 treatment. These effects were abolished with coadministration of GLP-2 and the VIP antagonist. GLP-2 was shown to activate neurons and to increase the number of cells expressing VIP in the submucosal plexus of the ileum. These findings suggest that GLP-2 acts as an anti-inflammatory agent through activation of enteric VIP neurons, independent of proliferative effects. They support further studies to examine the role of neural signaling in the regulation of intestinal inflammation.     

Apigenin supplementation protects the development of dextran sulfate sodium-induced murine experimental colitis by inhibiting canonical and non-canonical inflammasome signaling pathways

The present study was designed to elucidate the protective effects of dietary apigenin (API) enrichment in a chronic colitis model induced by DSS in mice. Inflammatory mediators and the possible role of canonical and non-canonical NLRP3 inflammasome signaling pathways in the beneficial effects of API under chronic inflammatory conditions were also explored. Six-week-old mice were randomized in four dietary groups: sham and control groups received standard diet (SD), and other two groups were fed with API at 0.1%. After 30 days, all groups except sham received 3% DSS in drinking water for 5 days followed by a regime of 21 days of water. Our results revealed that dietary API supplementation decreased the macroscopic and microscopic damage signs of colitis; also, it was capable to down-regulate mPGES, COX-2 and iNOS enzyme colonic expressions and to decrease serum matrix metalloproteinase (MMP-3) levels. Similarly, API diet reduced IL-1β and TNF-α proinflammatory cytokine secretions in primary LPS-stimulated splenocytes. Furthermore, we demonstrated that API anti-inflammatory activity was related with an inhibition of both canonical and non-canonical NLRP3 inflammasome pathways by decreasing proinflammatory IL-1β and IL-18 cytokine levels as a consequence of regulation of cleaved caspase-1 and caspase-11 enzymes. We conclude that API supplement might provide a basis for developing a new dietary strategy for the prevention of chronic ulcerative colitis.     

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.     

Attenuation of acute experimental colitis by preventing NPY Y1 receptor signaling

Neuropeptide Y (NPY), a 36-amino acid peptide, is widely expressed in the central and peripheral nervous system. NPY is involved in the regulation of several physiological processes, including energy balance, food intake, and nociception. Recently, we showed that activation of the NPY Y1 receptor is required for cutaneous neurogenic inflammation. Because neurogenic inflammation could participate in colitis, the aim of this study was to investigate the role of the NPY Y1 receptor in acute colitis using mice genetically deficient of NPY Y1 receptor. In addition, the Y1 receptor antagonist H409/22, was also investigated. Animals received 5% dextran sulfate sodium (DSS) in drinking water for 7 days. One group of animals also received the Y1 receptor antagonist, administered intraperitoneally twice daily. Disease activity was assessed daily for 7 days in all groups. DSS induced colitis in all animals resulting in weight loss, diarrhea, epithelial damage, crypt shortening, and inflammatory infiltration. However, clinical manifestation of the disease was markedly attenuated in Y1 null mutant mice as well as in mice receiving the Y1 antagonist. Histological analysis showed that tissue damage and ulceration were less severe in Y1-deficient animals. Consistent with the clinical and histological data, capsaicin-induced plasma extravasation was significantly reduced in the gut of Y1 null mutant animals compared with treated wild-type animals. These data indicate that NPY and Y1 receptor are involved in intestinal inflammation and suggest that inhibition of NPY Y1 receptor signaling may provide a novel therapeutic approach in the treatment of colonic inflammation.     

Murine Colitis Modeling using Dextran Sulfate Sodium (DSS)

Colitis can occur from viral or bacterial infections, ischemic insult, or autoimmune disorders; most notably Ulcerative Colitis and the colonic variant of Crohn’s Disease - Crohn’s Colitis. Acute colitis may present with abdominal pain and distention, malabsorption, diarrhea, hematochezia and mucus in the stool. We are beginning to understand the complex interactions between the environment, genetics, and epithelial barrier dysfunction in Inflammatory Bowel Disease and animal models of colitis have been essential in advancing our understanding of this disease. One popular model involves supplementing the drinking water of mice with low-molecular weight Dextran Sodium Sulfate (DSS), resulting in epithelial damage and a robust inflammatory response in the colon lasting several days ¹.Variations of this approach can be used to model acute injury, acute injury followed by repair, and repeated cycles of DSS interspersed with recovery modeling chronic inflammatory diseases ². After a single four-day treatment of 3% DSS in drinking water, mice show signs of acute colitis including weight loss, bloody stools, and diarrhea. Mice are euthanized at the conclusion of the treatment course and at necropsy dissected colons are processed and can be ''Swiss rolled" ³ to allow microscopic analysis of the entire colon or infused with formalin as "sausages" to allow macroscopic analysis. Tissue is then embedded in paraffin, sectioned, and stained for histologic review.Open in a separate windowClick here to view.^{(49M, flv)}     

Dual role of endogenous nitric oxide in development of dextran sodium sulfate-induced colitis in rats.

The role of nitric oxide (NO) in the etiology of ulcerative colitis is controversial with reports of the improvement and aggravation of colonic lesions by inducible NO synthase (iNOS) inhibitors. In the present study, we compared the effect of the selective iNOS inhibitor aminoguanidine and the nonselective NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) on a dextran sulfate sodium (DSS)-induced model of colitis in rats. Experimental colitis was induced by a 3% DSS-solution added to drinking water for 7 days. Aminoguanidine (5 approximately 20 mg/kg) and L-NAME (10 mg/kg) were administered p.o. twice daily for the first 3 days, the last 3 days or all 6 days of DSS treatment. Body weight and severity of colitis (diarrhea, bloody feces) were observed over a period of 7 days. DSS treatment resulted in severe colonic lesions, accompanied by diarrhea, bloody feces, decrease of body weight and colon shortening. All of the parameters investigated improved significantly with aminoguanidine treatment at 20 mg/kg for 6 days or the last 3 days of DSS-treatment, but L-NAME did not significantly affect the colitis during these periods. When L-NAME or aminoguanidine was given in the first 3 days of DSS treatment, the colonic lesions were slightly aggravated by L-NAME but not affected by aminoguanidine. The expression of iNOS mRNA was observed from the 3(rd) day of DSS treatment. These results suggested that endogenous NO exerts a biphasic influence on DSS-induced colitis, depending on the NOS isoenzyme; a beneficial effect of NO derived from constitutive NOS and a detrimental effect of NO produced by iNOS in the development of colitis.     

Somatostatin does not attenuate intestinal injury in dextran sodium sulphate-induced subacute colitis.

FRom several in vitro and in vivo studies involvement of somatostatin (SMS) in intestinal inflammation emerge. Acute colitis induced in rats is attenuated by the long-acting SMS analogue octreotide. We studied the potential beneficial effect of SMS on non-acute experimental colitis. BALB/c mice received either saline, SMS-14 (36 or 120 microg daily) or octreotide (3 microg daily) subcutaneously delivered by implant osmotic pumps. A non-acute colitis was induced by administration of dextran sodium sulphate (DSS) 10% in drinking water during 7 days. DSS evoked a mild, superficial pancolitis, most characterized by mucosal ulceration and submucosal influx of neutrophils. Neither SMS-14 nor octreotide reduced mucosal inflammatory score or macroscopical disease activity, although reduction of intestinal levels of interleukin-1beta (IL-1beta), IL-6 and IL-10 during DSS was augmented both by SMS and octreotide. A slight increase of neutrophil influx was seen during SMS administration in animals not exposed to DSS. In conclusion, SMS or its long-acting analogue did not reduce intestinal inflammation in non-acute DSS-induced colitis. According to the cytokine profile observed, SMS-14 and octreotide further diminished the reduction of intestinal macrophage and Th2 lymphocyte activity.     

Apurinic/apyrimidinic endonuclease 1, the sensitive marker for DNA deterioration in dextran sulfate sodium-induced acute colitis

Abstract

Mutations in mismatch repair (MMR) genes are commonly associated with the development of colorectal cancer. Additionally, base excision repair, which involves apurinic/apyrimidinic endonuclease 1 (APE1), recognizes and eliminates oxidative DNA damage. Here, we investigated the possible roles of APE1 in dextran sulfate sodium (DSS)-induced acute colitis using the young rat model. Four-week-old Sprague–Dawley rats were administered 2% DSS in drinking water for 1 week. MMR and APE1 expression levels were assessed by western blotting and immunohistochemistry. Following DSS treatment, growth of young rats failed and the animals had loose stools. Together with the histological changes associated with acute colitis, APE1 and MSH2 levels increased significantly at 3 and 5 days after DSS treatment, respectively. The difference between APE1 and MSH2 expression was significant. DSS-induced DNA damage and subsequent repair activity were evaluated by staining for 8-hydroxy-deoxyguanosine (8-OHdG) and APE1, respectively; 8-OHdG immunoreactivity increased throughout the colonic mucosa, while APE1 levels in the surface epithelium increased at an earlier timepoint. Taken together, our data suggest that changes in APE1 expression after DSS treatment occurred earlier and were more widespread than changes in MMR expression, suggesting that APE1 is more sensitive for prediction of DNA deterioration in DSS-induced 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.     

粪便微生物系移植通过影响炎症因子和肠道菌群结构缓解大鼠实验性结肠炎

炎症性肠病（inflammatory bowel disease,IBD）病因虽未明确,但目前认为,肠道细菌和肠黏膜免疫功能紊乱与IBD的发病密切相关。将40只SD大鼠分为健康对照组、模型组、粪便微生物系移植组（fecal microbiota transplantation,FMT）和柳氮磺胺吡啶组,后3组用2,4,6-三硝基苯磺酸（2,4,6-trinitrobenzene sulfonic acid, TNBS）灌肠造模,造模2 d后分别用粪便悬液和柳氮磺胺吡啶治疗1 w。末次给药后禁食1 d,对大鼠粪便进行菌群成分分析,股动脉取血,对K⁺ 、Na⁺ 、血清白蛋白（ALB）、白细胞计数（WBC）、中性粒细胞百分率（N%）、C-反应蛋白（CRP）、IL-1β、IL-10、IL-12和IL-17 水平进行检测,取结肠行病理学检查。结果发现,通过TNBS灌肠成功建立大鼠实验性结肠炎模型。与模型组比较,FMT组的K⁺和ALB明显升高(P<0.05),WBC、N%和CRP明显降低(P<0.05),IL-1β和IL-17明显降低(P<0.05),IL-10和IL-10/IL-12含量升高(P<0.05)。FMT能显著改善TNBS引起的肠道菌群变化,促进双歧杆菌的增殖而抑制脆弱拟杆菌和大肠杆菌的生长。上述结果证明,FMT可有效治疗炎症性肠病,其机制与其影响血清炎症因子水平和改善肠道菌群有关。     

Luminal antioxidants enhance the effects of mesalamine in the treatment of chemically induced colitis in rats

Previous experiments in rats with chemically induced colitis have shown that the antioxidant N-acetylcysteine plus mesalamine (5-ASA) exerted a significantly greater therapeutic effect in promoting mucosal healing when compared to either agent alone. The aims of the present study were to compare the effects of three antioxidants plus mesalamine vs. 5-ASA alone in treatment of colitis induced by trinitrobenzene sulfonic acid (TNBS) in rats. Methods: Three days following induction of TNBS colitis, rats received 8 days of rectal therapy with 5-ASA, or 5-ASA plus vitamin C (ascorbic acid), 5-ASA plus phenyl butylnitrone (PBN) and 5-ASA plus vitamin E (alpha-tocopherol). Distal colonic tissues were examined for microscopic colitis and myeloperoxidase (MPO) activity. Results: Global assessments of microscopic colitis induced by TNBS indicated that 5-ASA alone significantly changed colonic injury by -31%. Combination therapy with ascorbic acid plus 5-ASA or alpha-tocopherol plus 5-ASA caused further significant change in TNBS colitis by -65 and -82%, respectively. Each of these values was significantly below scores observed with 5-ASA as monotherapy. Reduction in colitis with PBN plus 5-ASA was not different from 5-ASA alone. MPO activity was decreased significantly in response to monotherapy with 5-ASA and each of the antioxidants plus 5-ASA when compared to TNBS. alpha-Tocopherol plus 5-ASA, however, was the only treatment strategy that reduced significantly MPO activity below that recorded for 5-ASA alone. In conclusion, our results indicate that antioxidants other than N-acetylcysteine significantly enhance the therapeutic effectiveness of 5-ASA in the treatment of TNBS colitis. alpha-Tocopherol plus 5-ASA exerted profound anti-inflammatory and reparative effects upon colitis induced by TNBS.     

The protective effect of the vagus nerve in a murine model of chronic relapsing colitis

The vagus nerve inhibits the response to systemic administration of endotoxin, and we have recently extended this observation to show that the vagus attenuates acute experimental colitis in mice. The purpose of the present study was to determine whether there is a tonic counterinflammatory influence of the vagus on colitis maintained over several weeks. We assessed disease activity index, macroscopic and histological damage, myeloperoxidase (MPO) activity, and Th1 and Th2 cytokine profiles in chronic colitis induced by administration of dextran sodium sulfate (DSS) in drinking water for three cycles during 5 days with 11 days of rest between each cycle (DSS 3, 2, 2%) in healthy and vagotomized C57BL/6 mice and in mice deficient in macrophage-colony stimulating factor (M-CSF). A pyloroplasty was performed in vagotomized mice. Vagotomy accelerated the onset and the severity of inflammation during the first and second but not the third cycle. Although macroscopic scores were not significantly changed, histological scores as well as MPO activity and colonic tissue levels of IL-1alpha, TNF-alpha, IFN-gamma, and IL-18 but not IL-4 were significantly increased in vagotomized mice compared with sham-operated mice that received DSS. In control mice (without colitis), vagotomy per se did not affect any inflammatory marker. Vagotomy had no effect on the colitis in M-CSF-derived macrophage-deficient mice. These results indicate that the vagus protects against acute relapses on a background of chronic inflammation. Identification of the molecular mechanisms underlying the protective role of parasympathetic nerves opens a new therapeutic avenue for the treatment of acute relapses of chronic inflammatory bowel disease.     

Genetic deletion of IL-25 (IL-17E) confers resistance to dextran sulfate sodium-induced colitis in mice

Background

IL-25 is emerging as a key regulator of inflammation in the intestinal mucosa because of its ability to promote type 2 while suppressing Th1 and Th17 responses. Several previous studies reported inconsistent results on the role of exogenous IL-25 in development of colonic inflammation and none were performed in animals with a genetic deletion of IL-25. We investigated the contribution of endogenous IL-25 to DSS-induced colitis using mice deficient in IL-25.

Results

Mice were exposed to DSS in drinking water ad libitum either for seven days (acute) or for three cycles of seven days with DSS followed by 14 days without DSS (chronic) to induce colitis, respectively. The loss of body weight, appearance of diarrhea and bloody stools, and shortening of colon length were significantly less pronounced in IL-25^?/? mice compared to WT mice after exposure to acute DSS. Histological examination showed that DSS-treated IL-25^?/? mice had only mild inflammation in the colon, while severe inflammation developed in DSS-treated WT mice. A significant up-regulation of IL-33 was observed in acute DSS-treated WT but not in the IL-25^?/? mice. There was significantly lower expression of pro-inflammatory cytokines in the colon of acute DSS-treated IL-25^?/? compared to WT mice. IL-25^?/? mice were also partially protected from chronic DSS challenge especially during the first 2 cycles of DSS exposure. In contrast to IL-25^?/? mice, IL-13^?/? mice were more susceptible to DSS-induced colitis. Finally, stimulation of T84 colonic epithelial cells with IL-25 up-regulated the expression of IL-33 and several pro-inflammatory cytokines.

Conclusions

These data indicate that endogenous IL-25 acts as a pro-inflammatory factor in DSS-induced colitis, which is unlikely to be mediated by IL-13 but possibly the induction of IL-33 and other pro-inflammatory mediators from colonic epithelial cells. The present study suggests that IL-25 may contribute to the pathogenesis of inflammatory bowel disease in at least a subgroup of patients.

     

NK-1 antagonist reduces colonic inflammation and oxidative stress in dextran sulfate-induced colitis in rats

Although substance P (SP) has been implicated as a mediator of neurogenic inflammation in the small intestine, little information is available regarding the role of SP in the pathogenesis of chronic ulcerative colitis. In this study, our aim was to investigate whether the intraperitoneal administration of a nonpeptide neurokinin-1 (NK-1) antagonist, CP-96345, which antagonizes the binding of SP to its NK-1 receptor, results in the attenuation of colonic inflammation induced in rats by 5% dextran sodium sulfate (DSS) in drinking water for 10 days compared with an inactive enantiomer, CP-96344. Disease activity was assessed daily for 10 days, after which colonic tissue damage was scored and myeloperoxidase activity and colon and urinary 8-isoprostanes were measured. Animals receiving DSS exhibited marked physical signs of colitis by day 5 compared with controls. Chronic administration of the NK-1 antagonist significantly reduced the disease activity index, mucosal myeloperoxidase activity, colonic tissue damage score, and mucosal and urinary levels of 8-isoprostanes compared with inactive enantiomer- or vehicle-injected (saline) animals receiving DSS alone. These data indicate that the administration of an NK-1 antagonist can attenuate colonic inflammation and oxidative stress and suggest a novel therapeutic approach in the treatment of chronic ulcerative colitis.     

Valsartan Attenuates Atherosclerosis via Upregulating the Th2 Immune Response in Prolonged Angiotensin II–Treated ApoE?/? Mice

Valsartan has a protective effect against hypertension and atherosclerosis in humans and experimental animal models. This study aimed to determine the effect of prolonged treatment with angiotensin II (Ang II) on atherosclerosis and the effect of valsartan on the activity of CD4⁺ T lymphocyte subsets. The results showed that prolonged treatment (8 wks) with exogenous Ang II resulted in an increased atherosclerotic plaque size and a switch of stable-to-unstable plaque via modulating on CD4⁺ T lymphocyte activity, including an increase in the T helper cell type 1 (Th1) and Th17 cells and a decrease in Th2 and regulatory T (Treg) cells. In contrast, valsartan treatment efficiently reversed the imbalance in CD4⁺ T lymphocyte activity, ameliorated atherosclerosis and elicited a stable plaque phenotype in addition to controlling blood pressure. In addition, treatment with anti-interleukin (IL)-5 monoclonal antibodies weakened the antiatherosclerotic effects of valsartan without affecting blood pressure.     

Role of M-CSF-dependent macrophages in colitis is driven by the nature of the inflammatory stimulus

Although macrophages are considered a critical factor in determining the severity of acute inflammatory responses in the gut, recent evidence has indicated that macrophages may also play a counterinflammatory role. In this study, we examined the role of a macrophage subset in two models of colitis. Macrophage colony-stimulating factor (M-CSF)-deficient osteopetrotic mice (op/op) and M-CSF-expressing heterozygote (+/?) mice were studied following the induction of colitis by either dinitrobenzene sulfonic acid (DNBS) or dextran sulfate sodium (DSS). DNBS induced a severe colitis in M-CSF-deficient op/op mice compared with +/? mice. This was associated with increased mortality and more severe macroscopic and microscopic injury. Colonic tissue myeloperoxidase (MPO) activity as well as concentrations of TNF-alpha, IL-1beta, and IL-6 were higher and IL-10 lower in op/op mice with DNBS colitis. The severity of inflammation and mortality was attenuated in op/op mice that had received human recombinant M-CSF prior to the induction of colitis. In contrast, op/op mice appeared less vulnerable to colitis induced by DSS. Macroscopic damage, microscopic injury, MPO activity, and tissue concentrations of TNF-alpha, IL-1beta, and IL-6 were all lower in op/op mice compared with +/? mice with DSS colitis, and no changes were seen in IL-10. Macrophage inflammatory protein-1alpha concentrations were increased in op/op but not +/? mice following colitis induced by DNBS but not DSS. These results indicate that M-CSF-dependent macrophages may play either a pro- or counterinflammatory role in acute experimental colitis, depending on the stimulus used to induce colitis.     

血管紧张素Ⅱ上调自发性高血压大鼠和Wistar-Kyoto大鼠血管平滑肌细胞外信号调节激酶的信号转导

本文研究血管紧张素Ⅱ(angiotensin Ⅱ,Ang Ⅱ)对自发性高血压大鼠(spontaneously hypertensive rat,SHR)和Wistar- Kyoto(WKY)大鼠血管平滑肌细胞(vascular smooth muscle cells．VSMCs)细胞外信号调节激酶(extracellular signal-regulated pro- tein kinases,ERKs)信号途径的影响。体外培养SHR和WKY大鼠的VSMCs,先在培养基中加入终浓度为1×105mmol／L 的缬沙坦或1×105mmol／L的PD98059或不加药物,再给予1×107mmol／L的Ang Ⅱ刺激24 h后收集细胞,以无血清培养基 培养的VSMCs作对照。用免疫沉淀法测定ERK活性;用Western-blot方法检测总ERK(total ERK,t-ERK)、磷酸化ERK (phosphorylated-ERK,p-ERK)及丝裂素活化蛋白激酶磷酸酶-1(mitogen-activated protem kinases phosphatase-1,MKP-1)水 平;用RT-PCR法半定量测定MKP-1 mRNA的含量。结果显示:(1)SHR和WKY大鼠Ang Ⅱ刺激组VSMCs中ERK活 性、p-ERK、MKP-1及MKP-1 mRNA水平均明显高于对照组(P<0．05);SHR和WKY大鼠Ang Ⅱ+缬沙坦组和Ang Ⅱ +PD98059组的上述指标与对照组比较均无显著性差异。(2)SHR大鼠VSMCs中ERK活性、P-ERK、MKP-1及MKP-1 mRNA均显著高于相同干预的WKY大鼠(P<0．01)。(3)SHR和WKY大鼠之间以及对照组、Ang Ⅱ刺激组、Ang Ⅱ+缬沙 坦组和Ang Ⅱ+PD98059组间VSMCs中t-ERK水平均无显著性差异。以上结果表明,Ang Ⅱ可能主要通过其1型(Ang Ⅱ type 1,AT)受体激活SHR和WKY大鼠VSMCs中ERK途径,增加ERK活性和p-ERK蛋白水平,继而引起MKP-1及 MKP-1 mRNA水平升高。