Angiographic studies in Crohn's disease and ulcerative colitis

The Role of the Mesentery in Crohn's Disease: The Contributions of Nerves, Vessels, Lymphatics, and Fat to the Pathogenesis and Disease Course

Crohn's disease (CD) is a complex gastrointestinal disorder involving multiple levels of cross talk between the immunological, neural, vascular, and endocrine systems. The current dominant theory in CD is based on the unidirectional axis of dysbiosis-innate immunity-adaptive immunity-mesentery-body system. Emerging clinical evidence strongly suggests that the axis be bidirectional. The morphologic and/or functional abnormalities in the mesenteric structures likely contribute to the disease progression of CD, to a less extent the disease initiation. In addition to adipocytes, mesentery contains nerves, blood vessels, lymphatics, stromal cells, and fibroblasts. By the secretion of adipokines that have endocrine functions, the mesenteric fat tissue exerts its activity in immunomodulation mainly through response to afferent signals, neuropeptides, and functional cytokines. Mesenteric nerves are involved in the pathogenesis and prognosis of CD mainly through neuropeptides. In addition to angiogenesis observed in CD, lymphatic obstruction, remodeling, and impaired contraction maybe a cause and consequence of CD. Lymphangiogenesis and angiogenesis play a concomitant role in the progress of chronic intestinal inflammation. Finally, the interaction between neuropeptides, adipokines, and vascular and lymphatic endothelia leads to adipose tissue remodeling, which makes the mesentery an active participator, not a bystander, in the disease initiation and precipitation CD. The identification of the role of mesentery, including the structure and function of mesenteric nerves, vessels, lymphatics, and fat, in the intestinal inflammation in CD has important implications in understanding its pathogenesis and clinical management.

Inflammatory bowel disease, liver diseases and endothelial function: is there a linkage?

Atherosclerosis is a systemic inflammatory disease able to deeply worsen the outcome of patients because of its serious clinical consequences. The complex inflammatory background underlining such a disease makes atherosclerosis linked to several systemic inflammatory conditions able to impair endothelial function and morphology. Inflammatory bowel diseases are a group of gastrointestinal diseases including Crohn's disease and ulcerative colitis, that is, syndromes characterized by changes in mucosal immunity and gastrointestinal physiology, which could negatively influence the vascular endothelial function and structure. Hepatitis (i.e. inflammatory diseases of the liver mainly due to viral infections) and nonalcoholic fatty liver disease could be aligned to inflammatory bowel disease in such an induction of atherosclerosis disease.Many studies tried to point out the relationship between bowel and liver inflammatory diseases and early vascular changes, considered the first step for atherosclerosis development.The aim of such a narrative review is to explain the relationship between inflammatory bowel disease, hepatitis and nonalcoholic fatty liver disease and their role in increasing cardiovascular risk profile due to early impairment in vascular function and morphology.

Environmental factors in the relapse and recurrence of inflammatory bowel disease: a review of the literature

INTRODUCTION

The causes of relapse in patients with Crohn's disease (CD) and ulcerative colitis (UC) are largely unknown. This paper reviews the epidemiological and clinical data on how medications (non-steroidal anti-inflammatory drugs, estrogens and antibiotics), lifestyle factors (smoking, psychological stress, diet and air pollution) may precipitate clinical relapses and recurrence. Potential biological mechanisms include: increasing thrombotic tendency, imbalances in prostaglandin synthesis, alterations in the composition of gut microbiota, and mucosal damage causing increased permeability.

RESULTS

The clinical epidemiological data consistently reports positive associations between smoking and relapses in CD, and inverse ones with UC. For NSAIDs and estrogens, the epidemiological findings are inconsistent, although general antibiotic use was associated with a reduced risk of relapse in CD. High levels of stress were positively associated with relapse, although psychological interventions did not have therapeutic benefits. The limited work on diet has reported sulphur-containing foods are positively associated with relapse in UC, but there is no work in CD. Ecological data reported positive correlations between air pollution levels and IBD hospitalisations.

CONCLUSIONS

In the future, to clarify this area, more clinical epidemiological work is required where detailed drug types and doses, and complete dietary intakes are measured, in specific forms of IBD. Such work could provide guidance to both patients and doctors to help maintain remission.

Anti-TNFα therapy early improves hemodynamics in local intestinal and extraintestinal circulations in active Crohn's disease

BACKGROUND AND AIMS

Active Crohn's disease affects intestine but may alter other locations as eyes vasculature. Previous studies provide evidence of elevated blood flow velocities (BFv) and volume (BFV) in superior mesenteric artery (SMA). We prospectively studied hemodynamics in feeding arteries of bowel and eyes before and 2 weeks after treatment induction with anti-TNFα.

METHODS

Fifteen patients (5 females, 10 males, 35.4 ± 9.0 years, mean ± SD) with active Crohn's disease for 7.5 ± 7.7 years were enrolled. Ultrasound imaging was performed before and 2 weeks after treatment in SMA and retrobulbar arteries: central retinal (CRA), temporal posterior ciliary (TPCA) and ophthalmic (OA) arteries. Serum markers of inflammation (CRP and fibrinogen), arterial blood pressures (ABP) and skin flow-mediated dilation (sFMD) were measured and patients were compared to 10 control age- and sex-matched subjects.

RESULTS

Before treatment, CRP and fibrinogen plasma concentrations, SMA BFV (339 ± 100 mL/min) were higher in patients than in controls by 8.5-fold (p<0.001), 1.4-fold (p<0.01) and 1.5-fold, respectively (p<0.01). BFv in CRA (3.5 ± 0.7 cm/s) and TPCA (4.4 ± 1.0 cm/s), sFMD (371 ± 469%) were significantly lower than in controls by 83%, 73% and 52% respectively (p<0.05). Two weeks after treatment, CRP and fibrinogen decreased, SMA BFV was normalized (230 ± 39L/min, p<0.01), BFv in CRA, TPCA and OA increased respectively to 4.0 ± 1.1 (p<0.05), 5.2 ± 1.4 (p<0.001), 8.9 ± 3 cm/s (p<0.05). ABP and sFMD remained unchanged.

CONCLUSIONS

In active Crohn's disease, a first anti-TNFα administration rapidly normalized concomitantly plasma inflammatory markers and blood-flows in the mesenteric and retrobulbar arteries without affecting blood pressure and endothelial function.

Assessment of wall inflammation and fibrosis in Crohn's disease: value of T1-weighted gadolinium-enhanced MR imaging

MRI is increasingly advocated as a robust method for quantifying disease activity in Crohn's disease. In particular, T1-weighted gadolinium-enhanced imaging shows considerable promise as a marker of inflammatory activity. However, interpretation of the literature must be made with an understanding of (i) the technical limitations of T1-weighted acquisition protocols and enhancement measurements; (ii) differences in standards of reference for disease activity employed between published studies; and (iii) important underlying macro and micro vascular changes in Crohn's disease. This review will focus specifically on the value of T1-weighted gadolinium-enhanced imaging in the assessment of wall inflammation and fibrosis.

Inflammation-induced intussusceptive angiogenesis in murine colitis

Intussusceptive angiogenesis is a morphogenetic process that forms new blood vessels by the division of a single blood vessel into two lumens. Here, we show that this process of intraluminal division participates in the inflammation-induced neovascularization associated with chemically induced murine colitis. In studies of both acute (4-7 days) and chronic (28-31 days) colitis, intravital microscopy of intravascular tracers demonstrated a twofold reduction in blood flow velocity. In the acute colitis model, the decreased velocity was associated with marked dilatation of the mucosal plexus. In contrast, chronic inflammation was associated with normal caliber vessels and duplication (and triplication) of the quasi-polygonal mucosal plexus. Scanning electron microscopy (SEM) of intravascular corrosion casts suggested that pillar formation and septation, previously linked to the morphogenetic process of intussusceptive angiogenesis, were present within days of the onset of inflammation. Four weeks after the onset of inflammation, SEM of vascular corrosion casts demonstrated replication of the mucosal plexus without significant evidence of sprouting angiogenesis. These data suggest that mucosal capillaries have comparable aggregate cross-sectional area in acute and chronic colitis; however, there is a significant increase in functional capillary density in chronic colitis. We conclude that intussusceptive angiogenesis is a fundamental mechanism of microvascular adaptation to prolonged inflammation.

Growth factor manipulation of intestinal angiogenesis: a possible new paradigm in the management of inflammatory bowel disease

BACKGROUND

Using the transgenic HLA-B27 rat model of inflammatory bowel disease (IBD), we have previously demonstrated hepatocyte growth factor's (HGF) potential to ameliorate diarrhea and decrease bowel injury. This study was designed to assess the effect of HGF on the neovascularization and inflammation in IBD.

MATERIALS AND METHODS

Female transgenic HLA-B27 rats were divided into two groups: group 1, saline (control, n = 6); group 2, HGF (150 mug/kg/d, n = 9). Treatments were delivered into the jugular vein via a 14-d subcutaneously placed osmotic mini-pump. Intestinal microvascular density (MVD), histologic inflammatory score, inflammatory cell infiltration, and cytokine expression (tumor necrosis factor-alpha {TNF-alpha}, interferon-gamma {IFN-gamma}, and interleuken-2 {IL-2}) were assessed. Analysis of variance (ANOVA) was used to determine statistical significance.

RESULTS

Administration of HGF resulted in variable but significant alterations in ileal and colonic histology compared with control animals. Compared with group 1, inflammatory cell infiltration was significantly reduced in group 2 (7.7 +/- 1.2 versus 13.3 +/- 2.1 SEM, P < 0.05). Enzyme linked immunosorbent assays (ELISA) demonstrated significantly less expression of ileal IFN-gamma, ileal IL-2 and colonic IL-2 in group 2 (P < 0.05) (Fig. 1). Of importance is that Group 2 exhibited significantly greater MVD in the ileum and colon, both P < 0.05 (Figs. 2 and 3).

CONCLUSION

HGF stimulates neovascularization while modulating the intestinal inflammatory response. This is the first demonstration in which a growth factor (HGF) stimulates nonpathologic angiogenesis in an animal model of IBD. HGF administration may be beneficial in the clinical management of IBD.

Multiple pathogenic roles of microvasculature in inflammatory bowel disease: a Jack of all trades

The etiology of Crohn's disease and ulcerative colitis, the two major forms of inflammatory bowel disease (IBD), is still largely unknown. However, it is now clear that the abnormalities underlying pathogenesis of intestinal inflammation are not restricted to those mediated by classic immune cells but also involve nonimmune cells. In particular, advances in vascular biology have outlined a central and multifaceted pathogenic role for the microcirculation in the initiation and perpetuation of IBD. The microcirculation and its endothelial lining play a crucial role in mucosal immune homeostasis through tight regulation of the nature and magnitude of leukocyte migration from the intravascular to the interstitial space. Chronically inflamed IBD microvessels display significant alterations in microvascular physiology and function compared with vessels from healthy and uninvolved IBD intestine. The investigation into human IBD has demonstrated how endothelial activation present in chronically inflamed IBD microvessels results in a functional phenotype that also includes leakiness, chemokine and cytokine expression, procoagulant activity, and angiogenesis. This review contemplates the newly uncovered contribution of intestinal microcirculation to pathogenesis and maintenance of chronic intestinal inflammation. In particular, we assess the multiple roles of the microvascular endothelium in innate immunity, leukocyte recruitment, coagulation and perfusion, and immune-driven angiogenesis in IBD.

Multiple pathogenic roles of microvasculature in inflammatory bowel disease: a Jack of all trades

The etiology of Crohn's disease and ulcerative colitis, the two major forms of inflammatory bowel disease (IBD), is still largely unknown. However, it is now clear that the abnormalities underlying pathogenesis of intestinal inflammation are not restricted to those mediated by classic immune cells but also involve nonimmune cells. In particular, advances in vascular biology have outlined a central and multifaceted pathogenic role for the microcirculation in the initiation and perpetuation of IBD. The microcirculation and its endothelial lining play a crucial role in mucosal immune homeostasis through tight regulation of the nature and magnitude of leukocyte migration from the intravascular to the interstitial space. Chronically inflamed IBD microvessels display significant alterations in microvascular physiology and function compared with vessels from healthy and uninvolved IBD intestine. The investigation into human IBD has demonstrated how endothelial activation present in chronically inflamed IBD microvessels results in a functional phenotype that also includes leakiness, chemokine and cytokine expression, procoagulant activity, and angiogenesis. This review contemplates the newly uncovered contribution of intestinal microcirculation to pathogenesis and maintenance of chronic intestinal inflammation. In particular, we assess the multiple roles of the microvascular endothelium in innate immunity, leukocyte recruitment, coagulation and perfusion, and immune-driven angiogenesis in IBD.

Doppler enhancement after intravenous levovist injection in Crohn's disease

Although transabdominal bowel sonography (TABS) has been proposed as a reliable tool to assess increased bowel wall thickness (BWT), the most common sonographic pattern in patients with Crohn's disease (CD), its accuracy is limited in the diagnosis of CD. We therefore tried to assess whether color Doppler enhancement with Levovist, a galactose-based intravenous sonographic contrast agent able to enhance the arterial Doppler signal, increases TABS accuracy. Thirty-one patients with ileal CD, diagnosed by endoscopy and enteroclysis, and 20 healthy volunteers were examined with conventional TABS. Color Doppler of the intramural enteric vessels was then performed before and after intravenous injection of Levovist. Twenty-two CD patients had a BWT >4 mm, and 16 of them presented with active disease. Two of the remaining nine CD patients, all with BWT <4 mm, presented with active disease. By means of color Doppler we identified six patients with inactive disease, normal BWT, and normal basal Doppler signal intensity, who showed an enhanced Doppler signal in intramural vessels after contrast agent bolus. Four of these patients, identified only by color Doppler after Levovist injection, relapsed within 6 months. In our experience, sensitivity and specificity of TABS, integrated with additional stimulated acoustic emission mode, were 96.7% and 100%, respectively. The use of Levovist in color Doppler increases the accuracy of TABS in CD diagnosis and follow-up.

Immunological basis of inflammatory bowel disease: role of the microcirculation

Inflammatory bowel disease (IBD) is a chronic inflammatory condition of the intestine and/or colon of unknown etiology in which patients suffer from severe diarrhea, rectal bleeding, abdominal pain, fever, and weight loss. Active episodes of IBD are characterized by vasodilation, venocongestion, edema, infiltration of large numbers of inflammatory cells, and erosions and ulcerations of the bowel. It is becoming increasingly apparent that chronic gut inflammation may result from a dysregulated immune response toward components of the normal intestinal flora, resulting in a sustained overproduction of proinflammatory cytokines and mediators. Many of these Th1 and macrophage-derived cytokines and lipid metabolites are known to activate microvascular endothelial cells, thereby promoting leukocyte recruitment into the intestinal interstitium. This review discusses the basic immune mechanisms involved in the regulation of inflammatory responses in the gut and describes how a breakdown in this protective response initiates chronic gut inflammation.

Doppler US in patients with crohn disease: vessel density in the diseased bowel reflects disease activity

PURPOSE

To determine if neovascularization associated with Crohn disease, as detected with Doppler ultrasonography (US), reflects clinical disease activity.

MATERIALS AND METHODS

A devised measurement, vessel density, was estimated with color Doppler US. Patients with Crohn disease underwent clinical and laboratory assessment in which the Crohn disease activity index was measured; patients underwent abdominal US the same week. Color Doppler US was performed by using a 7.5-10.0- or 8.0-12.0-MHz transducer, the lowest possible pulse repetition frequency without aliasing, a low wall filter, and high Doppler gain settings. The length and thickness of the affected loops were measured, and the number of color Doppler signals per square centimeter in the bowel loop was counted. Pulsed Doppler US was used to confirm that the signals originated from arteries or veins and not from movement artifacts.

RESULTS

Ninety-two patients (aged 7-20 years; mean, 14.85 years; 44 female, 48 male) underwent 119 examinations; 85 were performed in patients with active disease. Affected loops were thicker (10.6 vs 4. 6 mm; P: <.001) and had a higher vessel density with disease (69 of 119 examinations) than during remission (two of 34 examinations; P: <.001).

CONCLUSION

Vessel density in affected bowel loops, as estimated with Doppler US, and bowel wall thickness (>5 mm) reflect disease activity in patients with Crohn disease.

Role of non-nitric oxide non-prostaglandin endothelium-derived relaxing factor(s) in bradykinin vasodilation

The most conspicuous effect of bradykinin following its administration into the systemic circulation is a transient hypotension due to vasodilation. In the present study most of the available evidence regarding the mechanisms involved in bradykinin-induced arterial vasodilation is reviewed. It has become firmly established that in most species vasodilation in response to bradykinin is mediated by the release of endothelial relaxing factors following the activation of B2-receptors. Although in some cases the action of bradykinin is entirely mediated by the endothelial release of nitric oxide (NO) and/or prostacyclin (PGI2), a large amount of evidence has been accumulated during the last 10 years indicating that a non-NO/PGI2 factor accounts for bradykinin-induced vasodilation in a wide variety of perfused vascular beds and isolated small arteries from several species including humans. Since the effect of the non-NO/PGI2 endothelium-derived relaxing factor is practically abolished by disrupting the K+ electrochemical gradient together with the fact that bradykinin causes endothelium-dependent hyperpolarization of vascular smooth muscle cells, the action of such factor has been attributed to the opening of K+ channels in these cells. The pharmacological characteristics of these channels are not uniform among the different blood vessels in which they have been examined. Although there is some evidence indicating a role for KCa or KV channels, our findings in the mesenteric bed together with other reports indicate that the K+ channels involved do not correspond exactly to any of those already described. In addition, the chemical identity of such hyperpolarizing factor is still a matter of controversy. The postulated main contenders are epoxyeicosatrienoic acids or endocannabinoid agonists for the CB1-receptors. Based on the available reports and on data from our laboratory in the rat mesenteric bed, we conclude that the NO/PGI2-independent endothelium-dependent vasodilation induced by BK is unlikely to involve a cytochrome P450 arachidonic acid metabolite or an endocannabinoid agonist.

Doppler ultrasound measurement of intestinal blood flow in inflammatory bowel disease

BACKGROUND

Our aim was to assess the role of Doppler ultrasound (US) in detecting changes in the splanchnic hemodynamic variables measured in patients with active or quiescent inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS) and healthy subjects.

METHODS

Sixty-five patients, 31 with Crohn's disease (CD), 24 with ulcerative colitis (UC), 10 with IBS, and 10 matched normal subjects were evaluated by means of Doppler US. The mean velocity of portal and mesenteric venous flow, the blood flow volume of portal and mesenteric veins, and the resistance index (RI) of the superior mesenteric artery (SMA) were studied in all patients.

RESULTS

Patients with active IBD had a splanchnic venous flow that was significantly higher, and an RI of the SMA significantly lower, than the IBS patients and healthy controls; however, a higher portal and mesenteric blood flow and lower RI of the SMA was documented in patients with active UC but not in those in whom the disease was quiescent. Patients with quiescent CD had significantly higher portal and mesenteric blood flow and lower RI of the SMA than IBS and healthy controls. No significant differences were found between IBS patients, quiescent UC patients, and healthy controls.

CONCLUSION

This study shows that Doppler US can demonstrate splanchnic hemodynamic changes in active IBD patients and, in particular, can be used to differentiate between active and quiescent UC. However, the assessment of CD activity by means of Doppler US requires further investigation.

Spiral CT demonstration of hypervascularity in Crohn disease: "vascular jejunization of the ileum" or the "comb sign"

OBJECTIVE

To report spiral CT imaging features of the vascular alterations observed in active, early, or recurrent Crohn disease of the small bowel and colon.

METHODS

Spiral CT examinations of the abdomen and pelvis following oral and intravenous contrast were performed in two cases of active Crohn disease.

RESULTS

Spiral CT features of hypervascularity involving the mesenteric vessels of affected segments of bowel include vascular dilatation, tortuosity, and conspicuous prominence and wide spacing of the vasa recta (the "comb" sign). This is attributed to the factors of increased flow and the fibrofatty proliferation in the mesentery and serosa of the affected bowel.

CONCLUSION

Clinical application of these observations may enhance the diagnosis of Crohn disease presenting initially or as an acute recurrence in the differential diagnosis from other conditions.

Changes in splanchnic hemodynamics in inflammatory bowel disease. Non-invasive assessment by Doppler ultrasound flowmetry

An increase in splanchnic blood flow in both arterial and venous beds has been demonstrated in inflammatory bowel disease (IBD) by means of angiographic and scintigraphic studies. Doppler ultrasound (US) enables a non-invasive evaluation of splanchnic arterial inflow in the superior mesenteric artery (SMA) and of venous outflow in the portal vein. The aim of this study was to assess the role of Doppler US in detecting changes in the hemodynamic variables measured in patients with IBD. Forty-five patients with IBD were studied, including 22 with Crohn's disease (CD) and 23 with ulcerative colitis (UC), and compared with 45 matched normal subjects. The mean velocity of portal flow (Vmean) and the resistance index (RI) of the SMA were evaluated by Doppler US. In CD the Vmean of portal flow was significantly higher in patients with active disease than in controls (p less than 0.001) and patients with inactive disease (p less than 0.001). The RI of the SMA was significantly lower in active disease than in controls (p less than 0.005), but no significant difference was noted between active and inactive CD. Also in UC, the Vmean of portal flow was significantly higher in patients with active disease than in controls (p less than 0.01) and patients with inactive disease (p less than 0.05). The RI of the SMA was significantly lower in active disease than in controls (p less than 0.005) and in patients with inactive disease (p less than 0.005). Doppler follow-up studies were carried out in 10 patients after initiation of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Massive gastrointestinal bleeding in Crohn's disease: successful control by intra-arterial vasopressin infusion

A case of massive lower gastrointestinal bleeding from Crohn's disease is reported. This is an uncommon complication of the disease and the literature is reviewed. Successful control of gastrointestinal bleeding by intra-arterial vasopressin infusion has not previously been reported in Crohn's disease. We suggest that this technique may be used in an attempt to avoid surgery.

Angiographic evaluation of vascular changes in ulcerative colitis

Selective superior and inferior mesenteric angiography was carried out in 25 patients with ulcerative colitis. Vascular changes in angiography were compared with the clinical features of the patients. There was no correlation between vascular changes in angiography and the duration of illness or the extent of involvement. The vascular changes of large vessels, such as increased diameter of the inferior mesenteric artery, had better correlation with the severity or the activity of illness. However, we found that in some cases microcirculatory changes of small vessels of the intestinal wall, such as the findings of capillary brush or loss of normal tapering of vasa recta, still remain in remission of this disease. We assume that this microcirculatory disturbance plays an important role in the pathophysiology of ulcerative colitis.

Angiographic manifestions of regional enteritis

Regional enteritis may be a protean disease, easily diagnosed when the common clinical presentation is noted. Occasionally, however, "atypical" features lead to the clinical suspicion of neoplastic disease. Four patients underwent angiographic evaluation in this clinical setting, all demonstrating similar changes in the mesenteric arteries. A serrated, "corkscrew" pattern was present and corresponded well to the perivascular fibrosis noted histologically. Recognition of this angiographic pattern may be important in differentiating neoplastic from inflammatory disease processes.