Mediators of inflammation in chronic inflammatory bowel disease

Mast cell-mediated immune regulation in health and disease

Mast cells are important components of the immune system, and they perform pro-inflammatory as well as anti-inflammatory roles in the complex process of immune regulation in health and disease. Because of their strategic perivascular localization, sensitivity and adaptability to the microenvironment, and ability to release a variety of preformed and newly synthesized effector molecules, mast cells perform unique functions in almost all organs. Additionally, Mast cells express a wide range of surface and cytoplasmic receptors which enable them to respond to a variety of cytokines, chemicals, and pathogens. The mast cell's role as a cellular interface between external and internal environments as well as between vasculature and tissues is critical for protection and repair. Mast cell interactions with different immune and nonimmune cells through secreted inflammatory mediators may also turn in favor of disease promoting agents. First and forefront, mast cells are well recognized for their multifaceted functions in allergic diseases. Reciprocal communication between mast cells and endothelial cells in the presence of bacterial toxins in chronic/sub-clinical infections induce persistent vascular inflammation. We have shown that mast cell proteases and histamine induce endothelial inflammatory responses that are synergistically amplified by bacterial toxins. Mast cells have been shown to exacerbate vascular changes in normal states as well as in chronic or subclinical infections, particularly among cigarette smokers. Furthermore, a potential role of mast cells in SARS-CoV-2-induced dysfunction of the capillary-alveolar interface adds to the growing understanding of mast cells in viral infections. The interaction between mast cells and microglial cells in the brain further highlights their significance in neuroinflammation. This review highlights the significant role of mast cells as the interface that acts as sensor and early responder through interactions with cells in systemic organs and the nervous system.

Comparative treatment of Sulfasalazine+Ezetimibe combination and Sulfasalazine in a rat model with induced colitis

Ulcerative colitis is a chronic inflammatory disease with high mortality and morbidity worldwide. It causes inflammation in the lining of the colon, resulting in several symptoms that negatively impact the quality of life. Unfortunately, there is currently no known cure for this condition. Therefore, it is crucial to explore alternative treatment approaches. This research aimed to investigate the anti-inflammatory and antioxidative effects of a combination therapy involving Sulfasalazine+Ezetimibe compared to Sulfasalazine alone in a rat model of ulcerative colitis. Forty adult rats were divided into four groups for this study. The groups consisted of a control group (negative control), an acetic acid group (positive control), an acetic acid+Sulfasalazine (100 mg/kg per day) group, and an acetic acid+Sulfasalazine (50 mg/kg)+Ezetimibe (5 mg/kg) group. Rats were treated for one week, and colitis was induced by administering 2 ml of 4% (v/v) acetic acid inter-rectally. After sacrifice, the colonic tissue homogenate was analyzed for several markers, including proinflammatory cytokines (TNF-α, IL-1β, NF-κB), oxidative stress markers (malondialdehyde, myeloperoxidase), and adhesive molecule markers (E-selectin, ICAM-1). Sulfasalazine and the combination of Sulfasalazine+Ezetimibe significantly reduced the colonic levels of TNF-α, IL-1β, NF-κB, MDA, and E-selectin in the homogenate. However, the combination therapy of Sulfasalazine and Ezetimibe demonstrated a superior effect.

The Immune Change of the Lung and Bowel in an Ulcerative Colitis Rat Model and the Protective Effect of Sodium Houttuyfonate Combined With Matrine

Objective

To explore the immune change of lung injury of Ulcerative colitis (UC) by observing the changes of inherent immunity and adaptive immunity of the lung and bowel in UC rat models after the treatment of Sodium Houttuyfonate combined with Matrine.

Method

UC rat models were established with the mucous membrane of colon allergize combined with TNBS-alcohol enteroclysis for 1 week and 5 weeks. 1-week experimental rats were divided into normal group and model group, 5/each group. 5-weeks experimental rats were divided into normal group, model group, Sodium Houttuyfonate (2.9mg/ml) combined with Matrine (1.47mg/ml), and positive control sulfasalazine (10mg/ml), 5/each group. All rats were administered by gavage for 5 weeks. The histopathological and fibrotic changes in the lung and bowel were observed, and the expressions of Tumor Necrosis Factor (TNF)- α, interleukin (IL)-8 in the lung, bowel, and serum were detected by radio-immunity and immunohistochemistry, and the mRNA expressions of Toll-like receptor (TLR)-4, nuclear factor kappa (NF-κB), Macrophage migration inhibitory factor (MIF), Mucosal addressing cell adhesion molecule-1 (MadCAM1) and Pulmonary surfactant protein-A (SP-A) in the lung and bowel were detected by Real time-PCR.

Result

Compared with the normal group, the model rats had significant histopathological and fibrotic changes both in the lung and bowel, and all treatment groups were improved. After treatment, TLR4, IL-8, MIF, and TNF-α in the lung decreased (P<0.05); NF-KB, IL-8, and MIF in the bowel increased (P<0.05); MadCAM1 both in lung and bowel decreased (P<0.05); SP-A decreased in bowel and increased in the lung (P<0.05).

Conclusion

The cause of lung injury in this model was found to be related to inherent immunity and adaptive immunity, while the cause of bowel injury in this model was found to be mainly related to adaptive immunity. Sodium Houttuyfonate combined with Matrine could improve bowel and lung injury.

Lactobacillus acidophilus and HKL Suspension Alleviates Ulcerative Colitis in Rats by Regulating Gut Microbiota, Suppressing TLR9, and Promoting Metabolism

Ulcerative colitis (UC) is a chronic non-specific inflammatory bowel disease with complex pathogenesis. The intestinal flora disturbance affects the homeostasis of the intestinal environment, leading to metabolic imbalance and immune abnormalities of the host, contributing to the perpetuation of intestinal inflammation. We suggest that the combination of anti-inflammatory therapy and the regulation of intestinal flora balance may help in the treatment process. Previously, we used a combination treatment consisting of Lactobacillus acidophilus (Lac) and Chinese medicine Huan Kui Le (HKL) suspension in a UC rat model, where the combined intervention was more effective than either treatment alone. Herein, the mechanism of action of this combined treatment has been investigated using 16S rRNA sequencing, immunohistochemistry, and ELISA methods in the colon, and untargeted metabolomics profiling in serum. Colon protein expression levels of IL-13 and TGF-β were upregulated, whereas those of TLR9 and TLR4 were downregulated, consistent with an anti-inflammatory effect. In addition, gut microbiota structure changed, shown by a decrease in opportunistic pathogens correlated with intestinal inflammation, such as Klebsiella and Escherichia-Shigella, and an increase in beneficial bacteria such as Bifidobacterium. The latter correlated positively with IL-13 and TGF-β and negatively with IFN-γ. Finally, this treatment alleviated the disruption of the metabolic profile observed in UC rats by increasing short-chain fatty acid (SCFA)-producing bacteria in the colonic epithelium. This combination treatment also affected the metabolism of lactic acid, creatine, and glycine and inhibited the growth of Klebsiella. Overall, we suggest that treatment combining probiotics and traditional Chinese medicine is a novel strategy beneficial in UC that acts by modulating gut microbiota and its metabolites, TLR9, and cytokines in different pathways.

Microbial metabolite deoxycholic acid controls Clostridium perfringens-induced chicken necrotic enteritis through attenuating inflammatory cyclooxygenase signaling

Necrotic enteritis (NE) caused by Clostridium perfringens infection has reemerged as a prevalent poultry disease worldwide due to reduced usage of prophylactic antibiotics under consumer preferences and regulatory pressures. The lack of alternative antimicrobial strategies to control this disease is mainly due to limited insight into the relationship between NE pathogenesis, microbiome, and host responses. Here we showed that the microbial metabolic byproduct of secondary bile acid deoxycholic acid (DCA), at as low as 50 µM, inhibited 82.8% of C. perfringens growth in Tryptic Soy Broth (P < 0.05). Sequential Eimeria maxima and C. perfringens challenges significantly induced NE, severe intestinal inflammation, and body weight (BW) loss in broiler chickens. These negative effects were diminished (P < 0.05) by 1.5 g/kg DCA diet. At the cellular level, DCA alleviated NE-associated ileal epithelial death and significantly reduced lamina propria cell apoptosis. Interestingly, DCA reduced C. perfringens invasion into ileum (P < 0.05) without altering the bacterial ileal luminal colonization. Molecular analysis showed that DCA significantly reduced inflammatory mediators of Infγ, Litaf, Il1β, and Mmp9 mRNA accumulation in ileal tissue. Mechanism studies revealed that C. perfringens induced (P < 0.05) elevated expression of inflammatory mediators of Infγ, Litaf, and Ptgs2 (Cyclooxygenases-2 (COX-2) gene) in chicken splenocytes. Inhibiting the COX signaling by aspirin significantly attenuated INFγ-induced inflammatory response in the splenocytes. Consistent with the in vitro assay, chickens fed 0.12 g/kg aspirin diet protected the birds against NE-induced BW loss, ileal inflammation, and intestinal cell apoptosis. In conclusion, microbial metabolic product DCA prevents NE-induced BW loss and ileal inflammation through attenuating inflammatory response. These novel findings of microbiome protecting birds against NE provide new options on developing next generation antimicrobial alternatives against NE.

Cross sectional evaluation of the gut-microbiome metabolome axis in an Italian cohort of IBD patients

Inflammatory bowel disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract of uncertain origin, which includes ulcerative colitis (UC) and Crohn’s disease (CD). The composition of gut microbiota may change in IBD affected individuals, but whether dysbiosis is the cause or the consequence of inflammatory processes in the intestinal tissue is still unclear. Here, the composition of the microbiota and the metabolites in stool of 183 subjects (82 UC, 50 CD, and 51 healthy controls) were determined. The metabolites content and the microbiological profiles were significantly different between IBD and healthy subjects. In the IBD group, Firmicutes, Proteobacteria, Verrucomicrobia, and Fusobacteria were significantly increased, whereas Bacteroidetes and Cyanobacteria were decreased. At genus level Escherichia, Faecalibacterium, Streptococcus, Sutterella and Veillonella were increased, whereas Bacteroides, Flavobacterium, and Oscillospira decreased. Various metabolites including biogenic amines, amino acids, lipids, were significantly increased in IBD, while others, such as two B group vitamins, were decreased in IBD compared to healthy subjects. This study underlines the potential role of an inter-omics approach in understanding the metabolic pathways involved in IBD. The combined evaluation of metabolites and fecal microbiome can be useful to discriminate between healthy subjects and patients with IBD.

Protective effect of simvastatin and rosuvastatin on trinitrobenzene sulfonic acid-induced colitis in rats

Objective:

Statins have anti-inflammatory effects that are not directly related to their cholesterol lowering activity. This study was carried out to evaluate the effect of simvastatin or rosuvastatin on the extent of colonic mucosal damage and on the inflammatory response in trinitrobenzene sulfonic acid (TNBS)-induced ulcerative colitis.

Materials and Methods:

Ulcerative colitis was induced by single intrarectal injection of 120 mg/kg TNBS. Test groups were treated with simvastatin (10 mg/kg, p.o.) or rosuvastatin (10 mg/kg, p.o.). Colonic mucosal inflammation was evaluated clinically, biochemically, and histologically.

Result:

Disease activity index score in TNBS-treated rats, as determined by weight loss, stool consistency, fecal occult blood, were significantly lowers in simvastatin or rosuvastatin-treated rats than TNBS-treated animals. Simvastatin or rosuvastatin counteracted the reduction in colon length, decreased colon weight, neutrophil accumulation, and tumor necrosis factor-alpha level in TNBS-induced colitis. Simvastatin and rosuvastatin also inhibited the increase in oxidative stress levels after TNBS administration.

Conclusions:

These results suggest that simvastatin and rosuvastatin significantly ameliorate experimental colitis in rats, and these effects could be explained by their anti-inflammatory and antioxidant activity.

Bacteria-Derived Compatible Solutes Ectoine and 5α-Hydroxyectoine Act as Intestinal Barrier Stabilizers to Ameliorate Experimental Inflammatory Bowel Disease

Earlier studies showed that the compatible solute ectoine (1) given prophylactically before induction of colitis by 2,4,6-trinitrobenzenesulfonic acid (TNBS) in rats prevented histological changes induced in the colon and the associated rise in inflammatory mediators. This study was therefore conducted to investigate whether ectoine (1) and its 5α-hydroxy derivative (2) would also be effective in treating an already established condition. Two days after inducing colitis in rats by instilling TNBS/alcohol in the colon, animals were treated orally once daily for 1 week with either 1 or 2 (50, 100, 300 mg/kg). Twenty-four hours after the last drug administration rats were sacrificed. Ulcerative lesions and colon mass indices were reduced by 1 and 2 in a bell-shaped manner. Best results were obtained with 100 mg/kg ectoine (1) and 50 mg/kg 5α-hydroxyectoine (2). The solutes normalized the rise in myeloperoxidase, TNFα, and IL-1β induced by TNBS but did not affect levels of reduced glutathione or ICAM-1, while reducing the level of fecal calprotectin, an established marker for inflammatory bowel disease. The findings indicate that the naturally occurring compatible solutes ectoine (1) and 5α-hydroxyectoine (2) possess an optimum concentration that affords maximal intestinal barrier stabilization and could therefore prove useful for better management of human inflammatory bowel disease.

[Potential relevance of microRNAs in the diagnostics of inflammatory bowel diseases]

Inflammatory bowel diseases are chronic inflammatory disorders characterized by relapses and remissions. Several factors have been suggested to participate in their development, although their detailed pathogenesis still remains largely unknown. MicroRNAs are single strained, non-coding RNAs, consisting of 18-25 nucleotides that regulate gene expression at the posttranscriptional level. Aberrant expression of microRNAs has been found in several malignant tumors. Recently the role of microRNAs in the pathogenesis of inflammatory-autoimmune disorders (such as inflammatory bowel disease) is being intensively investigated. Beside their pathogenic roles, microRNAs can also be exploited as diagnostic markers, especially in cases where the interpretation of histological data is difficult. In this review the authors discuss recent findings in the field of microRNAs in the diagnosis and pathogenesis of inflammatory bowel diseases.

Protective effect of ginger volatile oil against acetic acid-induced colitis in rats: a light microscopic evaluation

OBJECTIVE

Ulcerative colitis is a chronically recurrent inflammatory bowel disease of unknown origin. In the present study, the effect of ginger (rhizome of Zingiber officinale Roscoe) volatile oil on a rat model of colitis was evaluated.

METHODS

Volatile oil of ginger with doses of 100, 200, and 400 mg/kg, prednisolone (4 mg/kg), or vehicle were administered orally to groups of male Wistar rats (n = 6) for 5 d. Animals were randomly divided into 6 groups, each group consisting of 6 rats. Colitis was induced by intracolonic instillation of 2 mL of 4% (v/v) acetic acid solution. All rats were sacrificed 24 h later and the tissue injuries were assessed macroscopically and histopathologically.

RESULTS

Ginger volatile oil with all doses reduced colon weight/length ratio (P < 0.01) and the effects were similar to the reference drugs. Higher oral doses of volatile oil (200 and 400 mg/kg) reduced ulcer severity (P < 0.05 and P < 0.01), ulcer area (P < 0.01) and ulcer index (P < 0.01). On the other hand, evaluation of microscopic scores showed that the dose of 400 mg/kg of volatile oil was effective to reduce inflammation severity (P < 0.01) and inflammation extent (P < 0.05) compared to the control group.

CONCLUSION

It is concluded that ginger volatile oil could effectively reduce symptoms of experimental colitis in a dose-dependent manner.

Inflammatory pathways of importance for management of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a group of chronic disorders of the gastrointestinal tract comprising Crohn’s disease (CD) and ulcerative colitis (UC). Their etiologies are unknown, but they are characterised by an imbalanced production of pro-inflammatory mediators, e.g., tumor necrosis factor (TNF)-α, as well as increased recruitment of leukocytes to the site of inflammation. Advantages in understanding the role of the inflammatory pathways in IBD and an inadequate response to conventional therapy in a large portion of patients, has over the last two decades lead to new therapies which includes the TNF inhibitors (TNFi), designed to target and neutralise the effect of TNF-α. TNFi have shown to be efficient in treating moderate to severe CD and UC. However, convenient alternative therapeutics targeting other immune pathways are needed for patients with IBD refractory to conventional therapy including TNFi. Indeed, several therapeutics are currently under development, and have shown success in clinical trials. These include antibodies targeting and neutralising interleukin-12/23, small pharmacologic Janus kinase inhibitors designed to block intracellular signaling of several pro-inflammatory cytokines, antibodies targeting integrins, and small anti-adhesion molecules that block adhesion between leukocytes and the intestinal vascular endothelium, reducing their infiltration into the inflamed mucosa. In this review we have elucidated the major signaling pathways of clinical importance for IBD therapy and highlighted the new promising therapies available. As stated in this paper several new treatment options are under development for the treatment of CD and UC, however, no drug fits all patients. Hence, optimisations of treatment regimens are warranted for the benefit of the patients either through biomarker establishment or other rationales to maximise the effect of the broad range of mode-of-actions of the present and future drugs in IBD.

Protective effect of magnesium lithospermate B against dextran sodiumsulfate induced ulcerative colitis in mice

Anti-platelet drugs have been used to treat inflammatory bowel disease. In this study, we observed the therapeutic effects of magnesium lithospermate B, a main component of salvianolate, on colitis induced by dextran sodiumsulfate (DSS). Colitis was induced by 5% DSS oral administration in BALB/C male mice. Magnesium lithospermate B (60-240mg/kg) was given by subcutaneous injection for 2 weeks. Then, mice were sacrificed; serum and colon tissues were collected for biomarker assay, histological examination, immunohistochemical study and real-time quantitative polymerase chain reaction. DSS induced gross bleeding, inflammation, crypt damage and mucosal damage in colon. Treatment with magnesium lithospermate B could reduce colon inflammation induced by DSS. Magnesium lithospermate B could reverse the high CD40/CD40L expression and hypercoagulable state induced by DSS in colon. This study showed that magnesium lithospermate B could be used to treat colitis. The protective effects of magnesium lithospermate B may be due to its effects on CD40/CD40L expression and blood clotting status.

Novel effects of ectoine, a bacteria-derived natural tetrahydropyrimidine, in experimental colitis

Evidence suggests an important role of intestinal barrier dysfunction in the etiology of inflammatory bowel disease (IBD). Therefore stabilizing mucosal barrier function constitutes a new therapeutic approach in its management. Ectoine is a compatible solute produced by aerobic chemoheterotrophic and halophilic/halotolerant bacteria, where it acts as osmoprotectant and effective biomembrane stabilizer, protecting the producing cells from extreme environmental stress. Since this natural compound was also shown to prevent inflammatory responses associated with IBD, its potential usefulness was studied in a model of colitis. Groups of rats were treated orally with different doses of ectoine (30-300 mg/kg) or sulfasalazine (reference drug) daily for 11 days. On day 8 colitis was induced by intracolonic instillation of 2,4,6-trinitrobenzenesulfonic acid, when overt signs of lesions develop within the next 3 days. On day 12, blood was withdrawn from the retro-orbital plexus of the rats and the animals were sacrificed. The colon was excised and examined macroscopically and microscopically. Relevant parameters of oxidative stress and inflammation were measured in serum and colon homogenates. Induction of colitis led to marked weight loss, significant histopathological changes of the colon, and variable changes in levels of myeloperoxidase, reduced glutathione, malondialdehyde, and all inflammatory markers tested. Treatment with ectoine ameliorated the inflammatory changes in TNBS-induced colitis. This effect was associated with reduction in the levels of TNF-α, IL-1β, ICAM-1, PGE2 and LTB4. The findings suggest that intestinal barrier stabilizers from natural sources could offer new therapeutic measures for the management of IBD.

MicroRNAs in inflammatory bowel disease - pathogenesis, diagnostics and therapeutics

The pathogenesis of inflammatory bowel disease (IBD) is complex and largely unknown. Until recently, research has focused on the study of protein regulators in inflammation to reveal the cellular and molecular networks in the pathogenesis of IBD. However, in the last few years, new and promising insights have been generated from studies describing an association between an altered expression of a specific class of non-coding RNAs, called microRNAs (miRs or miRNAs) and IBD. The short (approximately 22 nucleotides), endogenous, single-stranded RNAs are evolutionary conserved in animals and plants, and regulate specific target mRNAs at the post-transcriptional level. MiRNAs are involved in several biological processes, including development, cell differentiation, proliferation and apoptosis. Furthermore, it is estimated that miRNAs may be responsible for regulating the expression of nearly one-third of the genes in the human genome. Thus, miRNA deregulation often results in an impaired cellular function, and a disturbance of downstream gene regulation and signaling cascades, suggesting their implication in disease etiology. Despite the identification of more than 1900 mature human miRNAs, very little is known about their biological functions and functional targets. Recent studies have identified dysregulated miRNAs in tissue samples of IBD patients and have demonstrated similar differences in circulating miRNAs in the serum of IBD patients. Thus, there is great promise that miRNAs will aid in the early diagnosis of IBD, and in the development of personalized therapies. Here, we provide a short review of the current state-of-the-art of miRNAs in IBD pathogenesis, diagnostics and therapeutics.

Immunoexpression of cyclooxygenase-1 and -2 in ulcerative colitis

Ulcerative colitis (UC) is a disease of the colon and rectum characterized by a nonspecific chronic inflammation mediated by the concerted response of cellular and humoral events. Prostaglandins are synthesized by cyclooxygenase (COX)-1 and -2 and exhibit both pro- and anti-inflammatory activity. To evaluate COX-1 and COX-2 immunoexpression in 42 cases of UC and to correlate it with clinicopathological parameters, COX-1 and COX-2 expression was investigated by the immunohistochemistry method. Only patients with all pertinent clinical and evolutive data as well as with adequate biopsy material were included in the study. Fifteen samples of colorectal adenocarcinoma and 14 of large bowel with no histological changes were used for positive and negative controls, respectively. UC patients showed COX-1 immunoreactivity in epithelial cells in 29% of the cases and in inflammatory cells in 43%. COX-2 positivity in epithelial and inflammatory cells was found in 69% of the samples. The comparison between UC and the control groups revealed that the UC group had significantly more positive cases for COX-1 and COX-2 in inflammatory cells. Immunohistochemistry allowed the identification of COX-1 and COX-2 expression in epithelial and inflammatory cells in UC biopsies. No significant difference between COX-1 and COX-2 immunoreactivity in epithelial and inflammatory cells was observed regarding the clinicopathological parameters. COX-2 presented low expression in normal colon and high expression in colorectal adenocarcinoma. COX-2 might play a role in the pathophysiologic processes of inflammatory bowel disease and the development of neoplasia. Treatment with selective COX-2 inhibitors might be an additional option for therapy.

The intestinal anti-inflammatory effects of the novel agent UR-1505 in the TNBS model of rat colitis are mediated by T-lymphocyte inhibition

UR-1505 is a novel pentafluoropropoxy derivative of salicylic acid, selected from a series of salicylate derivatives, according to their activity as inhibitors of T-lymphocyte activation. This study describes the anti-inflammatory activity of UR-1505 on trinitrobenzenesulphonic acid-induced colitis in rat, an experimental model that resembles to Crohn's disease (CD), as well as its in vitro effects on T-cells and bone marrow-derived macrophages (BMDM) activation. UR-1505 showed intestinal anti-inflammatory effect, associated with reduced colonic levels of TNFalpha and LTB(4), inhibition of the expression of IFNgamma and iNOS, and lower colonic leukocyte infiltration. The in vitro assays revealed that UR-1505 also inhibited T-lymphocyte proliferation and IL-12/IFNgamma production, two of the main pro-inflammatory cytokines involved in the pathogenesis of CD. However, UR-1505 did not modify LPS- nor IFNgamma-induced activation in BMDM. Thus, UR-1505 specifically affects T-cells without modifying the activation of BMDM. In conclusion, the intestinal anti-inflammatory activity of UR-1505 seems to be mediated by a reduction in the recruitment of immune cells to the inflammatory foci, together with the inhibition of T-cell activation. These results suggest that UR-1505 may be an interesting candidate to be explored for the treatment of CD.

A potent and selective inhibitor of group IIa secretory phospholipase A2 protects rats from TNBS-induced colitis

Secretory phospholipase A(2) (sPLA(2)) enzymes have been implicated in the pathogenesis of human inflammatory bowel disease (IBD). In this study we compared the efficacy of a potent, new and highly selective inhibitor of group IIa human sPLA(2) enzyme (5-(4-benzyloxyphenyl)-4S-(7-phenylheptanoylamino)-pentanoic acid; sPLA(2)I), with that of sulfasalazine, in a rat model of trinitrobenzene sulfonic acid (TNBS)-induced colitis. Following a single oral dose of sPLA(2)I (5 mg/kg), pharmacoactive levels of drug were detected in the serum within 15 min and for up to 24 h by liquid chromatography mass spectrometry analysis. Rats treated with sPLA(2)I (5 mg/kg/day) prior to induction of colitis were significantly healthier than TNBS-alone rats, as shown by reduced mortality, improved food intake and increased body weight, and significantly reduced colon myeloperoxidase levels, edema, tumour necrosis factor-alpha levels, and colon macroscopic pathology scores after 8 days. Rats pretreated with sulfasalazine (100 mg/kg/day) also had reduced disease expression markers similar to the sPLA(2)I, but exhibited no improvement in colon edema. This study supports a role for the group IIa sPLA(2) enzyme in pathology associated with the TNBS rat model of IBD, and suggests a possible therapeutic application for selective inhibitors of group IIa sPLA(2) inhibitors in the treatment of IBD.

The diverse actions of nicotine and different extracted fractions from tobacco smoke against hapten-induced colitis in rats

The etiology of ulcerative colitis (UC) remains unknown, although the risk of developing UC is apparently higher in non-smokers and ex-smokers. We have demonstrated in a colitis animal model that exposure to tobacco smoke could attenuate UC pathogenesis. The present study aimed to investigate and compare between the modes of action of nicotine and different fractions of tobacco smoke extract in the development of experimental colitis. The hapten 2,4-dinitrobenzene sulfonic acid (DNBS) was used to induce colitis in Sprague-Dawley rats. Results indicated that both tobacco smoke exposure and subcutaneous nicotine differentially reduced colonic lesion size, myeloperoxidase (MPO) activity, luminol-amplified free radical generation, and leukotriene B4 formation in the inflamed colon of colitis animals. These phenomena were accompanied by the downregulation of colonic interleukin (IL)-1beta and monocyte chemoattractant protein (MCP)-1 protein expression. By treating the colitis animals with various tobacco extracts, we further discovered that ethanol extract from filtered tobacco smoke could attenuate DNBS-evoked colonic damage and the elevated MPO activity, while at the same time it downregulated colonic IL-1beta and MCP-1 protein expression. In contrast, the highest dose of the chloroform extract from the cigarette filter caused aggravating effects and overexpression of the pro-inflammatory cytokines and chemokines. These data suggest that effective attenuation of DNBS-induced colitis by tobacco smoke could be due to its nicotine content and possibly other flavonoid components found in the ethanol smoke extract.

Effect of pharmacologically induced smooth muscle activation on permeability in murine colitis

BACKGROUND

Both intestinal permeability and contractility are altered in inflammatory bowel disease. Little is known about their mutual relation. Therefore, an in vitro organ bath technique was developed to investigate the simultaneous effects of inflammation on permeability and smooth muscle contractility in different segments of the colon.

METHODS AND MATERIALS

BALB/c mice were exposed to a 10% dextran sulphate sodium drinking water solution for 7 days to induce a mild colitis, while control mice received normal tap water. Intestinal segments were placed in an oxygenated organ bath containing Krebs buffer. Permeability was measured by the transport of the marker molecules 3H-mannitol and 14C-polyethyleneglycol 4000. Contractility was measured through a pressure sensor. Smooth muscle relaxation was obtained by salbutamol and l-phenylephrine, whereas contraction was achieved by carbachol and 1-(3-chlorophenyl)-biguanide.

RESULTS

The intensity of mucosal inflammation increased throughout the colon. Also, regional differences were observed in intestinal permeability. In both normal and inflamed distal colon segments, permeability was diminished compared with proximal colon segments and the non-inflamed ileum. Permeability in inflamed distal colon segments was significantly decreased compared with normal distal segments. Pharmacologically induced relaxation of smooth muscles did not affect this diminished permeability, although an increased motility positively affected permeability in inflamed and non-inflamed distal colon.

CONCLUSIONS

Inflammation and permeability is inversely related. The use of pro-kinetics could counteract this disturbed permeability and, in turn, could regulate the disturbed production of inflammatory mediators.

Spatial heterogeneity of TNF-alpha-induced T cell migration to colonic mucosa is mediated by MAdCAM-1 and VCAM-1

Relatively little is known about how recirculation of lymphocytes through the inflamed intestinal mucosa is regulated. The aim of this study was to investigate the dynamic process of T lymphocyte-endothelial cell adhesion in TNF-alpha-challenged murine colonic mucosa by intravital microscopy. T lymphocytes from spleen (SPL) and intestinal lamina propria (LPL) were fluorescence labeled, and their adhesion to microvessels in the colonic mucosa was observed. In TNF-alpha (25 microg/kg)-stimulated colonic venules, an enhanced adhesion of SPL and LPL was demonstrated, with dominant recruitment of LPLs. The magnitude of the increased LPL adhesion was more significant in the colon than in the small intestine. These T lymphocyte interactions in the colonic mucosa were significantly reduced by blocking MAbs against either mucosal addressin cell adhesion molecule-1 (MAdCAM-1), VCAM-1, alpha(4)-integrin, or beta(7)-integrin but not by anti-ICAM-1. Immunohistochemistry revealed significant MAdCAM-1 expression in the lamina propria and VCAM-1 expression in the submucosa of TNF-alpha-treated colon. Spatial heterogeneity of MAdCAM-1 and VCAM-1 activation following TNF-alpha challenge may promote specific T lymphocyte recruitment in the inflamed colonic mucosa.

Suppression of dextran sulfate sodium-induced colitis in kininogen-deficient rats and non-peptide B2 receptor antagonist-treated rats

Various proinflammatory mediators are believed to be involved in the processes and symptoms of ulcerative colitis (UC). To determine whether endogenous kinin enhances the severity of UC, we induced experimental colitis (EC) in kininogen-deficient mutant rats and tested the effect of a non-peptide B2 receptor antagonist. EC was induced in male kininogen-deficient Brown Norway-Katholiek rats (BN-Ka) and normal Brown Norway-Kitasato rats (BN-Ki) with 5% dextran sulfate sodium (DSS). Sprague-Dawley rats (SD) were also used. Colon length, body weight and hematocrit were determined for 7 days. Effects of FR173657, an orally active B2 antagonist, were tested. The colon length was shortened in BN-Ki with DSS treatment, but not in BN-Ka, and the difference between their lengths was significant. The hematocrit value was also reduced in BN-Ki, and the difference in hematocrit between BN-Ki and BN-Ka was significant. In SD, shortening of the colon and reduction in hematocrit were also observable, and both were blunted by FR173657. The survival rate in SD given DSS for 7 days was 68%, but FR173657 treatment restored it significantly to 100%. These results suggest that the endogenous kinins generated from the kallikrein-kinin system have a significant role in the development of EC.

Delineation of the protective action of zinc sulfate on ulcerative colitis in rats

The protective action of zinc compounds in Crohn's disease-like inflammatory bowel disease in animals has been shown. A similar action of zinc sulfate on ulcerative colitis has not been defined. The present study aimed to delineate the protective action of zinc sulfate and the pathogenic mechanisms of 2,4-dinitrobenzene sulfonic acid (DNBS)-induced ulcerative colitis in rats. Zinc sulfate at different concentrations was given either orally (p.o.) or rectally (p.r.) to rats at 42, 48, 66 and 72 h following the induction of colonic inflammation by DNBS. Rats were killed 96 h after instillation of DNBS rectally to assess the severity of colonic damage, myeloperoxidase and xanthine oxidase activities. The involvement of mast cell degranulation and histamine release in the pathogenesis of DNBS-induced colitis was determined by using a mast cell stabilizer (ketotifen) and histamine receptor blockers (terfenadine and ranitidine). DNBS given rectally produced inflammation and ulceration in rats with a pathology resembling ulcerative colitis. Myeloperoxidase activity but not xanthine oxidase activity was sharply increased by this agent. Intrarectal administration of zinc solution and parenteral injection of histamine blockers significantly reduced tissue damage and myeloperoxidase but not xanthine oxidase activity. Ketotifen, a mast cell stabilizer, also significantly decreased mucosal injury and myeloperoxidase activity in the colon. In conclusion, mast cell degranulation followed by histamine release plays an important role in the pathogenesis of DNBS-induced ulcerative colitis. Zinc given rectally has a therapeutic effect against this colitis model, perhaps through the reduction of inflammation and inhibition of the above pathogenic mechanisms.

In vitro effects of E3040, a dual inhibitor of 5-lipoxygenase and thromboxane A(2) synthetase, on eicosanoid production

In vitro pharmacological profiles of E3040, 6-hydroxy-5, 7-dimethyl-2-(methylamino)-4-(3-pyridylmethyl) benzothiazole were investigated. Against the 5-lipoxygenase activity of rat basophilic leukemia cells, E3040 and zileuton (a 5-lipoxygenase inhibitor) had an IC(50) of 0.23 and 0.93 microM, respectively. Against the thromboxane A(2) synthetase activity of human platelets, E3040 had an IC(50) of 0.01 microM, which was comparable to that of OKY-1581 (sodium (E)-3-[4-(3-pyridylmethyl) phenyl]-2-methylacrylate, a thromboxane A(2) synthetase inhibitor). Against cyclooxygenase activity of sheep seminal vesicles, E3040 showed no inhibition (IC(50), >300 microM). Sulfasalazine and 5-aminosalicylic acid, therapeutic drugs for inflammatory bowel disease, inhibited 5-lipoxygenase activity with an IC(50) of 293 and 970 microM, respectively. Sulfasalazine inhibited thromboxane A(2) synthetase activity with an IC(50) of 20 microM. In rat peritoneal leukocytes, E3040 inhibited leukotriene B(4) and thromboxane B(2) production with an IC(50) of 0.17 and 0.24 microM, respectively. E3040 inhibited leukotriene B(4) production in human neutrophils and thromboxane B(2) production in human platelets (IC(50) of 0.21 and 0.09 microM, respectively). These results indicated that E3040 potently inhibited 5-lipoxygenase and thromboxane A(2) synthetase and blocked leukotriene B(4) and thromboxane B(2) production in rat peritoneal and human blood cells.

Increased serum levels of eotaxin in patients with inflammatory bowel disease

BACKGROUND

The CC-chemokines eotaxin and eotaxin-2, produced by epithelial and phagocytic cells, are potent and selective chemoattractants for eosinophils and basophils. The eosinophil is a potent inflammatory cell thought to play an important role in the pathogenesis of inflammatory bowel disease (IBD). In this study we investigated the serum concentrations of eotaxin and eotaxin-2 in patients with Crohn disease and ulcerative colitis.

METHODS

Thirty-one patients with Crohn disease, 35 patients with ulcerative colitis and 41 control patients were studied. Eotaxin and eotaxin-2 serum levels were measured with solid phase sandwich enzyme-linked immunosorbent assays.

RESULTS

Significantly increased serum eotaxin levels were observed in both patients with Crohn disease (289.4+/-591.5 pg/ml) and ulcerative colitis (207.0+/-243.4 pg/ml) when compared with controls (138.0+/-107.8 pg/ml) (P < 0.01). Moreover, patients with active Crohn disease and ulcerative colitis showed significantly higher serum eotaxin levels than patients with quiescent disease (434.0+/-776.8 pg/ml versus 113.8+/-65.4 pg/ml in Crohn disease and 295.7+/-337.1 versus 121.2+/-91.9 pg/ml in ulcerative colitis, P < 0.05). In contrast, there was no significant difference in eotaxin-2 serum levels among patients with Crohn disease (863.5+/-448.2 pg/ml), ulcerative colitis (1028.3+/-431.4 pg/ml) and controls (981.4+/-539.4 pg/ml).

CONCLUSIONS

Eotaxin is significantly increased in serum of patients with active Crohn disease and ulcerative colitis, suggesting that this cytokine may play a role in the pathogenesis of IBD.

Neuroendocrine changes in colon of mice with a disrupted IL-2 gene

Neuroendocrine peptides have a variety of physiological functions in the gastrointestinal tract. This study was carried out to investigate the impact of IL-2 deficiency on the neuroendocrine system in normal colon, and the neuroendocrine changes during colonic inflammation. Mice with homozygous disrupted IL-2 gene (IL-2-/-) spontaneously developed a bowel disease with similarities to human ulcerative colitis. Different types of colonic endocrine cells and myenteric nerves were analysed in the IL-2-/- mice using immunomorphometry. The neuropeptide contents in the colonic tissues were determined by radioimmunoassay. Age-matched healthy IL-2+/- and IL-2+/+ mice served as controls and the colonic IL-2 levels were compared between these two groups of mice by ELISA. Our data showed that less than half the amount of IL-2 was synthesized in the colon of IL-2+/- mice compared with the IL-2+/+ wild-type mice. Two major differences in the neuroendocrine colon were found between the mice with an intact and disrupted IL-2 gene. One was age-related. The frequencies of various endocrine cells and myenteric nerves increased with age in the IL-2+/+ mice. However, no such increases were seen in the mice with a disrupted IL-2 gene. Instead, the volume densities of enteroglucagon, serotonin cells and substance P (SP), vasoactive intestinal polypeptide (VIP) and total myenteric nerves were lower in the older IL-2+/- and IL-2-/- mice compared with the wild type. The other was disease-related. Polypeptide YY (PYY) cells and tissue levels of PYY, SP and VIP were significantly decreased in the IL-2-/- mice during the course of bowel inflammation compared with the healthy IL-2+/- and IL-2+/+ controls. These findings indicate that colonic neuroendocrine alterations did occur in the mice with a disrupted IL-2 gene and diminished local IL-2 level, suggesting a role of IL-2 in the regulation of the neuroendocrine system and a prevalent interaction between the immune and neuroendocrine systems in normal colon. On the other hand, there were some changes that seemed to correlate with the bowel inflammatory process. They might be associated with the impaired function in inflamed gut and contribute to the development and/or prolongation of disease.

The effect of dexamethasone treatment on murine colitis

BACKGROUND

Corticosteroids are used as anti-inflammatory drugs in the treatment of inflammatory bowel disease. We wanted to know whether dexamethasone (DEX) treatment could prevent dextran sulphate sodium (DSS)-induced colitis in mice.

METHODS

Acute colitis was induced after oral administration of 10% DSS for 2 days. Controls received normal tap water. Five days before and during DSS or tap water exposure half the group was treated with 0.06 mg/day DEX, and the other half received saline. After the mice had been killed, macroscopic observation and histologic evaluation were used to determine the degree of colonic inflammation.

RESULTS

The macroscopic score was significantly increased in untreated DSS mice (P < 0.001). The induction of colitis was not prevented by DEX pretreatment (5.9 +/- 0.9 versus 4.2 +/- 0.6; NS). In addition, the macroscopic scores of DEX-treated controls were significantly increased (1.8 +/- 0.2 versus 0.7 +/- 0.2; P = 0.007), which suggests that DEX has a stimulating effect on colitis induction. The histology score was significantly increased in untreated DSS mice compared with controls (P = 0.016). Analogous to the macroscopic scoring results, the histology score of DEX-treated controls was significantly increased compared with untreated controls (P = 0.046).

CONCLUSIONS

Pretreatment with dexamethasone did not prevent the induction of acute DSS colitis, reflected by both aggravated macroscopic and histologic inflammation scores.

Chronic gastrointestinal inflammation

Chronic gastrointestinal inflammation is one of the most common types of inflammatory process which affects humans. It is diverse in aetiology, pathogenesis and manifestation. There are also features of chronic inflammation at different sites within the gastrointestinal tract which provide a common thread in terms of the approaches which may be used in investigating these intriguing processes. This paper provides an overview of the mucosal changes in chronic gastrointestinal inflammation. Conserved and variable features of inflammation at different sites extending from the oral cavity to the rectum are highlighted. The involvement of different inflammatory cell types within any diagnostic entity is considered and the progression from an acute to chronic inflammatory condition explored. Important issues in the maintenance of a chronic inflammatory state are the balance between pro- and anti-inflammatory pressures, the driving force behind the inflammation and immune response that is occurring and the mechanisms for curtailment of unwanted or harmful responses which may damage the host. Thus inflammation is likely to result when there is persistence of a driving force and/or imbalance in the pro- and anti-inflammatory mechanisms in the tissue involved.

Immune markers for monitoring the progression of autoimmune disease

The incidence of immune-mediated diseases is increasing worldwide. Reliable immune markers for monitoring disease progression and also the effect of therapeutic interventions are urgently needed in order to investigate preventive or therapeutic measures effectively. At a recent workshop held on 5 December 1998 in Copenhagen, the state of research on surrogate markers in Type 1 diabetes was discussed and compared with the experience in multiple sclerosis, inflammatory bowel disease and transplantation.

Review article: the potential role of nitric oxide in chronic inflammatory bowel disorders

The aetiology of the chronic inflammatory bowel diseases-ulcerative colitis and Crohn's disease-as well as 'microscopic colitis'-both collagenous (COC) and lymphocytic colitis (LC)-remains unknown. Autoimmune mechanisms, cytokine polymorphism, commensal bacteria, infectious agents and vascular impairment have all been proposed as playing important roles in the pathogenesis of this spectrum of diseases. A variety of proinflammatory mediators, including tumour necrosis factor alpha, interleukin-1beta, interferon gamma, leukotriene B4 and platelet activating factor, promote the adherence of phagocytes to the venular endothelium and extravasation of these cells into the colonic mucosa. In addition to large amounts of nitric oxide (NO), injurious peroxynitrite may be formed in the epithelium by the inducible nitric oxide synthase (iNOS), which is considered to elicit cytotoxicity by the generation of superoxide with reduced L-arginine availability. In active ulcerative colitis, and to a lesser extent in Crohn's disease, a greatly increased production of NO has been demonstrated by indirect and direct measurements. Surprisingly, even higher rates of production have been observed in COC-a condition which is never associated with injurious inflammation. The latter observation favours the notion that NO promotes mucosal integrity. Further evidence for a protective role of NO in chronic inflammatory bowel disorders is provided by the observation of increased susceptibility to the induction of experi mental colitis in 'knock-out' mice deficient in iNOS. Selective inhibitors of iNOS activity, as well as topical L-arginine, may therefore prove beneficial in inflammatory bowel disease by reducing the production of superoxide by iNOS, while only the former option may be expected to reduce diarrhoea in chronic inflammatory bowel disorders. Clearly, further experimental work needs to be done before testing topical L-arginine in human inflammatory bowel disease.

Coincidence of hereditary angioedema (HAE) with Crohn's disease

A patient with two diseases, based presumably on different immunopathological mechanisms, hereditary angioedema (HAE) and Crohn's disease, was followed for 8 years. For more than three years of this observation period, detailed laboratory data were also available and could be analyzed. Both diseases had severe courses requiring chronic treatment with danazol and sulfasalazine, respectively. During exacerbation of Crohn's disease, the levels of C4 was found to be significantly lower than during the periods free of symptoms of both diseases. This drop was probably due to an impaired C1-inhibitor activity. HAE attacks and acute exacerbation of Crohn's disease never occurred simultaneously. This finding may be a mere chance but may also indicate that the different immunopathological processes underlying HAE and Crohn's disease influence each other.

Autocrine regulation of epithelial permeability by hypoxia: role for polarized release of tumor necrosis factor alpha

BACKGROUND & AIMS

The intestinal mucosa is lined by a monolayer of protective epithelial cells. This barrier is regulated by immune-derived factors such as interferon gamma (IFN-gamma). Because of the high volume of blood flow, the intestine is a primary target for hypoxic damage. We hypothesize that epithelial cytokine responses are regulated by hypoxia.

METHODS

T84 intestinal epithelial cells were used to assess alterations in permeability, major histocompatibility complex class II induction, cytokine receptor expression, and cytokine release in response to combinations of IFN-gamma and cellular hypoxia.

RESULTS

Hypoxia potentiated the influence of IFN-gamma on epithelial barrier function. Such responses were conferrable in a >/=10-kilodalton conditioned media fraction from hypoxic epithelia. Subsequent experiments identified this factor as epithelium-derived tumor necrosis factor alpha (TNF-alpha). Add-back of recombinant TNF-alpha in combination with IFN-gamma to normoxic epithelia recapitulated hypoxia and identified basolaterally polarized TNF-alpha receptor types I and II on intestinal epithelia. A similar pattern of TNF-alpha-receptor expression was observed on native intestinal epithelia. Specific inhibition of TNF-alpha using neutralizing antibody or alpha-N-phthalimidoglutarimide (thalidomide) resulted in reversal of the hypoxia-evoked responses.

CONCLUSIONS

These studies indicate that during hypoxia, epithelium-derived mediators such as TNF-alpha have the potential to regulate permeability through autocrine pathways.

The circulating common gamma chain (CD132) in inflammatory bowel disease

OBJECTIVE

Inflammatory bowel disease (IBD) is characterized by T cell activation. Activated T cells shed interleukin-2 receptors (IL-2R) in a soluble form. A positive correlation between sIL-2Ralpha (CD25) and disease activity is well documented in IBD, whereas IL-2Rgamma (CD132) has not been investigated in this respect. Sera from 42 patients with ulcerative colitis (UC), 34 with Crohn's disease (CD), 31 healthy volunteers, and 12 patients with infectious enterocolitis were obtained.

METHODS

Disease activity was scored according to a semiquantitative score for UC and CD. sIL-2R alpha chain and gamma chain were assessed by sandwich ELISA techniques using monoclonal antibodies specific for CD25 and CD132, respectively.

RESULTS

The concentration of IL-2Ralpha chain (CD25) was found to be median 3.8 ng/ml in healthy volunteers versus 7.0 ng/ml in UC patients (p < 0.001), and 9.6 ng/ml in CD patients (p < 0.001). With respect to IL-2Rgamma (CD132), significantly higher amounts were found in CD patients: 6.6 ng/ml as compared with healthy controls <1.0 ng/ml (p < 0.004). A Kruskal-Wallis test revealed a significant correlation between alpha chain and disease activity in CD (p < 0.001), and further significantly higher gamma chain levels were found in active CD (p = 0.03). For UC patients, a statistically significant increase of the alpha chain with increasing disease activity (p < 0.01) was observed, whereas no significant changes of the gamma chain levels were found (p > 0.05). A difference of gamma chain levels were found between CD and UC in moderate and severe disease activity (p < 0.05). Further analyses revealed that mesalazine did not influence the IL-2Ralpha or -gamma concentration either in UC or in CD patients.

CONCLUSION

An increased circulating level of the soluble common gamma chain (CD132) seems to be found in CD, and an overlap exists between CD and UC.