Successful treatment of an acute flare of steroid-resistant Crohn's colitis during pregnancy with unfractionated heparin

Contribution of Blood Vessel Activation, Remodeling and Barrier Function to Inflammatory Bowel Diseases

Inflammatory bowel diseases (IBDs) consist of a group of chronic inflammatory disorders with a complex etiology, which represent a clinical challenge due to their often therapy-refractory nature. In IBD, inflammation of the intestinal mucosa is characterized by strong and sustained leukocyte infiltration, resulting in the loss of epithelial barrier function and subsequent tissue destruction. This is accompanied by the activation and the massive remodeling of mucosal micro-vessels. The role of the gut vasculature in the induction and perpetuation of mucosal inflammation is receiving increasing recognition. While the vascular barrier is considered to offer protection against bacterial translocation and sepsis after the breakdown of the epithelial barrier, endothelium activation and angiogenesis are thought to promote inflammation. The present review examines the respective pathological contributions of the different phenotypical changes observed in the microvascular endothelium during IBD, and provides an overview of potential vessel-specific targeted therapy options for the treatment of IBD.

PAR-1 Antagonism to Promote Gut Mucosa Healing in Crohn's Disease Patients: A New Avenue for CVT120165

A new paradigm has been added for the treatment of inflammatory bowel diseases such as Crohn's disease and ulcerative colitis. In addition to resolving symptoms and inflammatory cell activation, the objective of tissue repair and mucosal healing is also now considered a primary goal. In the search of mediators that would be responsible for delayed mucosal healing, protease-activated receptor-1 (PAR-1) has emerged as a most interesting target. Indeed, in Crohn's disease, the endogenous PAR-1 agonist thrombin is drastically activated. Activation of PAR-1 is known to be associated with epithelial dysfunctions that hamper mucosal homeostasis. This review gathers the scientific evidences of a potential role for PAR-1 in mucosal damage and mucosal dysfunctions associated with chronic intestinal inflammation. The potential clinical benefits of PAR-1 antagonism to promote mucosal repair in CD patients are discussed. Targeted local delivery of a PAR-1 antagonist molecule such as CVT120165, a formulated version of the FDA-approved PAR-1 antagonist vorapaxar, at the mucosa of Crohn's disease patients could be proposed as a new indication for IBD that could be rapidly tested in clinical trials.

Increased Mucosal Thrombin is Associated with Crohn's Disease and Causes Inflammatory Damage through Protease-activated Receptors Activation

BACKGROUND AND AIMS

Thrombin levels in the colon of Crohn's disease patients have recently been found to be elevated 100-fold compared with healthy controls. Our aim was to determine whether and how dysregulated thrombin activity could contribute to local tissue malfunctions associated with Crohn's disease.

METHODS

Thrombin activity was studied in tissues from Crohn's disease patients and healthy controls. Intracolonic administration of thrombin to wild-type or protease-activated receptor-deficient mice was used to assess the effects and mechanisms of local thrombin upregulation. Colitis was induced in rats and mice by the intracolonic administration of trinitrobenzene sulphonic acid.

RESULTS

Active forms of thrombin were increased in Crohn's disease patient tissues. Elevated thrombin expression and activity were associated with intestinal epithelial cells. Increased thrombin activity and expression were also a feature of experimental colitis in rats. Colonic exposure to doses of active thrombin comparable to what is found in inflammatory bowel disease tissues caused mucosal damage and tissue dysfunctions in mice, through a mechanism involving both protease-activated receptors -1 and -4. Intracolonic administration of the thrombin inhibitor dabigatran, as well as inhibition of protease-activated receptor-1, prevented trinitrobenzene sulphonic acid-induced colitis in rodent models.

CONCLUSIONS

Our data demonstrated that increased local thrombin activity, as it occurs in the colon of patients with inflammatory bowel disease, causes mucosal damage and inflammation. Colonic thrombin and protease-activated receptor-1 appear as possible mechanisms involved in mucosal damage and loss of function and therefore represent potential therapeutic targets for treating inflammatory bowel disease.

Heparin-Coated Albumin Nanoparticles for Drug Combination in Targeting Inflamed Intestine

Targeting areas of inflammation offers potential therapeutic and diagnostic benefits by maximizing drug and imaging marker on-target effects while minimizing systemic exposure that can be associated with adverse side effects. This strategy is particularly beneficial in the management of inflammatory bowel disease (IBD). Here an inflammation-targeting (IT) approach based on heparin-coated human serum albumin nanoparticles (HEP-HSA NPs) that utilize the increased intestinal permeability and changes in electrostatic interaction at the site of intestinal inflammation is described. Using small-molecule and biologic drugs as a model for drug combination, the HEP-HSA NPs demonstrate the capacity to load both drugs simultaneously; the dual-drug loaded HEP-HSA NPs exhibit a higher anti-inflammatory effect than both of the single-drug loaded NPs in vitro and selectively bind to inflamed intestine after enema administration in vivo in a murine model of colitis. Importantly, analyses of the physicochemical characteristics and targeting capacities of these NPs indicate that HEP coating modulates NP binding to the inflamed intestine, providing a foundation for future IT-NP formulation development.

Possible immunosuppressive effects of drug exposure and environmental and nutritional effects on infection and vaccination

A variety of drugs which are not primarily considered to be immunosuppressive agents have been described to modulate the humoral and cellular immune response in humans or animals. Thereby they may have an influence on the effectiveness and possible side effects of vaccines. This mini review lists some of the different substance classes and also some of endogeneous, infectious, nutritional, and environmental influences with suspected capability to interfere with immunizations. Studies in most cases focused on substances with known immunosuppressive functions, but there is growing evidence for immunomodulatory effects also of commonly used drugs with wide distribution. In particular combinations of those antiproliferative and antiphlogistic side effects of different substance classes have not been studied in detail but may substantially interfere with the development of a functional humoral and cellular immune response. The drugs of importance include antipyretics, anticoagulants, tranquilizers, and substances influencing lipid metabolism but also commonly used drugs of abuse like alcohol or cannabinoids. Additional substances of environmental, nutritional, or microbiological origin may also play a role but their combinatory/synergistic effects have been disregarded so far due to the lack of systematic data and the complex study designs necessary to elucidate those complex epidemiologic questions.

Low molecular weight heparin relieves experimental colitis in mice by downregulating IL-1β and inhibiting syndecan-1 shedding in the intestinal mucosa

Low molecular weight heparin (LMWH) exhibits anti-inflammatory properties, but its effect on inflammation in colitis remains unclear. This study aimed to evaluate the therapeutic effects of LMWH on dextran sulfate sodium (DSS)-induced colitis in mice, in which acute colitis progresses to chronic colitis, and to explore the potential mechanism involved in this process. C57BL/6 mice were randomly divided into control, DSS, and DSS plus LMWH groups (n = 18). Disease activity was scored by a disease activity index (DAI). Histological changes were evaluated by hematoxylin and eosin (HE) staining. The mRNA levels of syndecan-1, interleukin (IL)-1β, and IL-10 were determined by quantitative reverse transcription polymerase chain reaction. Protein expression of syndecan-1 was detected by immunohistochemistry. The serum syndecan-1 level was examined by a dot immunobinding assay. LMWH ameliorated the disease activity of colitis induced by DSS administration in mice. Colon destruction with the appearance of crypt damage, goblet cell loss, and a larger ulcer was found on day 12 after DSS administration, which was greatly relieved by the treatment of LMWH. LMWH upregulated syndecan-1 expression in the intestinal mucosa and reduced the serum syndecan-1 level on days 12 and 20 after DSS administration (P<0.05 vs. DSS group). In addition, LMWH significantly decreased the expression of both IL-1β and IL-10 mRNA on days 12 and 20 (P<0.05 vs. DSS group). LMWH has therapeutic effects on colitis by downregulating inflammatory cytokines and inhibiting syndecan-1 shedding in the intestinal mucosa.

On the role of ischemia in the pathogenesis of IBD: a review

Inflammatory bowel disease (IBD) is a chronic intestinal disorder comprising 2 distinct but often overlapping diseases: Crohn's disease and ulcerative colitis. Although much research to identify the etiology of IBD has focused on genetic constitution, infectious causes, and immune dysregulation, its exact cause and pathogenesis remain incompletely understood. Mesenteric blood flow, the intestinal microcirculation, and intestinal ischemia also have been proposed as etiologic, although they remain less-explored themes despite evidence suggesting a contributory role in IBD pathogenesis. The anatomy, architecture, and function of the splanchnic microcirculation will be reviewed here with regard to the development of intestinal microvascular ischemia, a pathologic process that appears to precede the classic changes that characterize IBD.

Enhanced antithrombotic effects of unfractionated heparin in rats after repeated oral doses and its relationship to endothelial heparin concentration

BACKGROUND AND PURPOSE

An oral, single dose of 7.5 mg kg(-1) of unfractionated heparin (UFH) reduces thrombosis by 50% in a rat model of venous thrombosis. As long-term use is required clinically, our objectives were to study the antithrombotic effects following repeated oral UFH administration.

EXPERIMENTAL APPROACH

Bovine lung UFH was administered by oral gavage to rats in 3 doses of 7.5 mg kg(-1) each 12, 24, 48, and 72 h apart; and in 3 or 15 doses of 1 mg kg(-1) every 48 h. The last dose was given immediately after thrombus initiation where 10% formalin in methanol was applied to the jugular vein. The vessel was examined for thrombosis 4 h later. Amounts of heparin in tissue and endothelium, and plasma anticoagulant activity were measured.

KEY RESULTS

When 3 x 7.5 mg kg(-1) heparin was given, thrombotic incidence was most reduced at 48 h dose-intervals and was significantly less than single dose treatment. There was a negative correlation between endothelial heparin content and thrombotic incidence, but not anticoagulant activity. When 3 doses of 1 mg kg(-1) every 48 h were given, thrombotic incidence was similar to single dose treatment. When 15 doses were given, total thrombotic incidence was less than for 3 doses and was similar to that after s.c. administration.

CONCLUSIONS AND IMPLICATIONS

Antithrombotic activity increased with repeated doses of oral UFH, with antithrombotic effects similar to s.c. administration. Antithrombotic activity was related to heparin on endothelium.

Heparanase upregulation by colonic epithelium in inflammatory bowel disease

Heparanase is an endo-beta-D-glucuronidase capable of cleaving heparan sulfate (HS) side chains at a limited number of sites, yielding HS fragments of still appreciable size ( approximately 5-7 kDa). Heparanase activity has long been detected in a number of cell types and tissues. Importantly, heparanase activity correlated with the metastatic potential of tumor-derived cells, attributed to enhanced cell dissemination as a consequence of HS cleavage and remodeling of the extracellular matrix barrier. Similarly, heparanase activity was implicated in neovascularization, inflammation and autoimmunity, involving migration of vascular endothelial cells and activated cells of the immune system. The involvement of heparanase in inflammatory processes of the gastrointestinal tract has not been examined. Here, we utilized immunohistochemical analysis to investigate heparanase expression in acute and chronic inflammatory conditions. Heparanase expression was not detected in specimens derived from normal colon tissue. In contrast, strong heparanase staining was observed in Crohn's disease and ulcerative colitis, but not in infectious colitis. Interestingly, heparanase staining was primarily observed in epithelial rather than immune cells. Importantly, un-fractionated as well as low molecular weight heparin (enoxaparin), which exhibit a strong inhibitory activity towards heparanase, have proven efficacious in ulcerative colitis and Crohn's disease patients, suggesting that heparanase is actively involved in these pathologies and thus may be considered as a target for the development of anti-inflammatory therapies.

Evidence for the absorption of heparin by rat stomach

Antithrombotic activity and heparin with endothelium are observed in rats when heparin is administered by the oral route. Peak endothelial concentrations at 6 min suggest rapid absorption. To identify the site of absorption, stomach and duodenum were isolated by tying the pyloric sphincter of male Wistar rats and heparin (unfractionated bovine lung, 60 mg/kg) was administered by stomach tube or injected into the duodenum. Heparin in plasma and aortic endothelium, collected within 15 min, was determined by densitometry following agarose gel electrophoresis with toluidine blue staining. Heparin was recovered in 5 of 10 endothelial (0.136+/-0.068 microg/cm(2)) and 6 of 10 plasma (0.06+/-0.02 microg/ml) samples when administered in the stomach and in 0 of 9 endothelial and 2 of 9 plasma (0.02+/-0.02 microg/ml) samples when injected into the duodenum. To further study heparin distribution, stomach layers were separated and analysed 15 min and 4h following heparin administration by stomach tube. Heparin was recovered in muscle and mucosal layers as well as washes indicating that heparin passes through stomach tissue. Heparin was also recovered from the portal vein, endothelium and lung. These results indicate that heparin is absorbed following oral administration and that the stomach is an important site of absorption.

Inhibitory effect of heparin-derived oligosaccharides on secretion of interleukin-4 and interleukin-5 from human peripheral blood T lymphocytes

AIM: To investigate the inhibitory effect of heparin-derived oligosaccharides (Oligs) on secretion of interleukin-4 (IL-4) and interleukin-5 (IL-5) from human peripheral blood T lymphocytes (PBTLs).

METHODS: Oligs were prepared by three different heparin depolymerization methods and separated by gel filtration chromatography. PBTLs from ten adult patients with allergic eosinophilic gastroenteritis were treated with phytahematoagglutinin (PHA) and Oligs. The supernatants from the cell culture of PBTLs were harvested and subjected to the determination of IL-4 and IL-5 contents by ELISA method.

RESULTS: At the concentration of 5 μg/mL, Oligs with different M_r had different effects on the secretion of IL-4 and IL-5. The tetrasaccharide with M_r of 1142, produced by depolymerizing heparin with hydrogen peroxide, had the strongest inhibitory effect on the secretion of IL-4. It decreased the IL-4 content from 375.6 ± 39.2 ng/L (PHA group) to 12.5 ± 5.7 ng/L (P < 0.01). The hexasaccharide with M_r of 1806, produced by depolymerizing heparin with β -elimination method, had the strongest inhibitory effect on the secretion of IL-5. It decreased the IL-5 content from 289.2 ± 33.4 ng/L (PHA group) to 22.0 ± 5.2 ng/L (P < 0.01).

CONCLUSION: The inhibitory activity of Oligs on the secretion of IL-4 and IL-5 from human PBTLs closely depends on their molecular structure, and there may be an essential structure to act as an inhibitor. The most effective inhibitors of IL-4 and IL-5 secretion are tetrasaccharides and hexasaccharides, respectively.

Irritable bowel syndrome and inflammatory bowel disease in pregnancy

Irritable bowel syndrome and inflammatory bowel disease are gastrointestinal disorders affecting young adults. The peak incidence of irritable bowel syndrome and inflammatory bowel disease is in the late adolescence and early adult years, the time during which many women are planning and beginning their families. Since the potential for life-altering changes and pregnancy complications exist with these diseases, affected pregnant women present a challenge for the gastroenterologist, pregnancy provider, and nurses caring for them. This article outlines what is known about these diseases and their effect on fertility and pregnancy as well as their clinical management during pregnancy.