Opioid Analgesics Do Not Improve Abdominal Pain or Quality of Life in Crohn's Disease.

BACKGROUND: Abdominal pain and opioid analgesic use are common in Crohn's disease (CD). AIMS: We sought to identify factors associated with abdominal pain in CD and evaluate the impact of opioid analgesics on pain and quality-of-life scores in this setting. METHODS: We performed a longitudinal cohort study using a prospective, consented IBD natural history registry from a single academic center between 2009 and 2013. Consecutive CD patients were followed for at least 1 year after an index visit. Data were abstracted regarding pain experience (from validated surveys), inflammatory activity (using endoscopic/histologic findings), laboratory studies, coexistent psychiatric disorders, medical therapy, opioid analgesic, and tobacco use. RESULTS: Of 542 CD patients (56.6% women), 232 (42.8%) described abdominal pain. Individuals with pain were more likely to undergo surgery and were more frequently prescribed analgesics and/or antidepressants/anxiolytics. Elevated ESR (OR 1.79; 95%CI 1.11-2.87), coexistent anxiety/depression (OR 1.87; 95%CI 1.13-3.09), smoking (OR 2.08; 95%CI 1.27-3.40), and opioid use (OR 2.46; 95%CI 1.33-4.57) were independently associated with abdominal pain. Eighty patients (14.8%) were prescribed opioids, while 31 began taking them at or after the index visit. Patients started on opioids demonstrated no improvement in abdominal pain or quality-of-life scores on follow-up compared to patients not taking opioids. CONCLUSIONS: Abdominal pain is common in CD and is associated with significant opioid analgesic utilization and increased incidence of anxiety/depression, smoking, and elevated inflammatory markers. Importantly, opioid use in CD was not associated with improvement in pain or quality-of-life scores. These findings reinforce the limitations of currently available analgesics in IBD and support exploration of alternative therapies.

Novel model of peripheral tissue trauma-induced inflammation and gastrointestinal dysmotility.

BACKGROUND: Trauma is a leading cause of death and although the gut is recognized as the 'motor' of post-traumatic systemic inflammatory response syndrome and multiple organ failure, studies on the gastrointestinal (GI) tract are few. Our objectives were to create a precisely controllable tissue injury model in which GI motility, systemic inflammation and wound fluid can be analyzed. METHODS: A non-narcotic murine trauma model was developed by the subcutaneous dorsal trans-implantation of a devitalized donor syngeneic harvested tissue-bone matrix (TBX), which was precisely adjusted to % total body weight and studied after 21 h. Gastrointestinal transit histograms were plotted after the oral administration of non-digestible FITC-dextran and geometric centers calculated. Organ bath evaluated jejunal circular muscle contractility. Multiplex electrochemiluminescence measurements of serum and TBX wound fluid inflammatory mediators were performed. KEY RESULTS: Increasing TBX amounts progressively delayed transit, whereas TBX heat denaturation or decellularization prevented ileus and death. In the TBX(17.5%) model, jejunal muscle contractility was suppressed and a systemic inflammatory response developed as significant serum elevations in IL-6, keratinocyte cytokine and IL-10 compared to sham. In addition, inflammatory responses within the wound fluid showed elevated levels of preformed IL-1ß and TNF-α, whereas, 21 h after implantation IL-1ß, IL-6 and keratinocyte cytokine were significantly increased in the wound. CONCLUSIONS & INFERENCES: A novel donor tissue-bone matrix trauma model was developed that is precisely adjustable and recapitulates important clinical phenomena. The non-narcotic model demonstrated that increasing tissue injury progressively caused ileus, initiated a systemic inflammatory response and developed inflammatory changes within the wound.

The CHOICE trial: adalimumab demonstrates safety, fistula healing, improved quality of life and increased work productivity in patients with Crohn's disease who failed prior infliximab therapy.

BACKGROUND: Adalimumab induces and maintains remission in adults with Crohn's disease. AIM: To evaluate safety, fistula healing, quality of life and work productivity in adalimumab-treated patients who failed infliximab, including primary nonresponders. METHODS: After a ≥8-week infliximab washout, patients with moderate-to-severe Crohn's disease received open-label adalimumab as induction (160/80 mg at weeks 0/2) and maintenance (40 mg every other week) therapies. At/after 8 weeks, patients with flare/nonresponse could receive weekly therapy. Minimum study duration was 8 weeks, continuing until the commercial availability of adalimumab for Crohn's disease. RESULTS: Of 673 patients enrolled, 17% were infliximab primary nonresponders and 83% were initial responders. Three percent of patients had serious infections (mainly abscesses). Complete fistula healing was achieved by 34/88 (39%) patients with baseline fistulas. Improvements in quality of life and work productivity were sustained from week 4 to week 24 for all patients, as well as the subgroup of primary nonresponders. CONCLUSIONS: Blinded clinical trials have shown adalimumab to be both an effective first-line therapy for anti-TNF-naïve patients and an important treatment option for infliximab-refractory or -intolerant patients. This trial presents open-label experience to support further the safety and effectiveness of adalimumab in patients who failed infliximab therapy, including primary nonresponders (NCT00338650).

Curcumin inhibits VEGF-mediated angiogenesis in human intestinal microvascular endothelial cells through COX-2 and MAPK inhibition.

BACKGROUND: Angiogenesis, the growth of new blood vessels, is a critical homeostatic mechanism which regulates vascular populations in response to physiological requirements and pathophysiological demand, including chronic inflammation and cancer. The importance of angiogenesis in gastrointestinal chronic inflammation and cancer has been defined, as antiangiogenic therapy has demonstrated benefit in models of inflammatory bowel disease and colon cancer treatment. Curcumin is a natural product undergoing evaluation for the treatment of chronic inflammation, including inflammatory bowel disease (IBD). The effect of curcumin on human intestinal angiogenesis is not defined. METHODS: The antiangiogenic effect of curcumin on in vitro angiogenesis was examined using primary cultures of human intestinal microvascular endothelial cells (HIMECs), stimulated with vascular endothelial growth factor (VEGF). RESULTS: Curcumin inhibited proliferation, cell migration and tube formation in HIMECs induced by VEGF. Activation of HIMECs by VEGF resulted in enhanced expression of cyclo-oxygenase-2 (COX-2) mRNA, protein and prostaglandin E(2) (PGE(2)) production. Pretreatment of HIMECs with 10 microM curcumin as well as 1 microM NS398, a selective inhibitor of COX-2, resulted in inhibition of COX-2 at the mRNA and protein level and PGE(2) production. Similarly COX-2 expression in HIMECs was significantly inhibited by Jun N-terminal kinase (JNK; SP600125) and p38 mitogen-activated protein kinase (MAPK; SB203580) inhibitors and was reduced by p44/42 MAPK inhibitor (PD098059). CONCLUSIONS: Taken together, these data demonstrate an important role for COX-2 in the regulation of angiogenesis in HIMECs via MAPKs. Moreover, curcumin inhibits microvascular endothelial cell angiogenesis through inhibition of COX-2 expression and PGE(2) production, suggesting that this natural product possesses antiangiogenic properties, which warrants further investigation as adjuvant treatment of IBD and cancer.

Excess hospitalisation burden associated with Clostridium difficile in patients with inflammatory bowel disease.

BACKGROUND: Clostridium difficile is an important cause of diarrhoea in hospitalised patients. An increasing number of cases of C difficile colitis occur in patients with inflammatory bowel disease (IBD)-Crohn's disease (CD), ulcerative colitis (UC). OBJECTIVE: To estimate the potential excess morbidity and mortality associated with C difficile in hospitalised patients with IBD. METHODS: Data from the Nationwide Inpatient Sample (2003) were analysed and outcomes were examined of patients hospitalised with both C difficile colitis and IBD compared with those hospitalised for either condition alone. The primary outcome was in-hospital mortality. A subgroup analysis was also performed comparing outcomes of C difficile infection in patients with CD and UC. RESULTS: 2804 discharges were diagnosed as having both C difficile and IBD, 44,400 as having C difficile alone, and 77,366 as having IBD alone. On multivariate analysis, patients in the C difficile-IBD group had a four times greater mortality than patients admitted to hospital for IBD alone (aOR = 4.7, 95% CI 2.9 to 7.9) or C difficile alone (aOR = 2.2, 95% CI 1.4 to 3.4), and stayed in the hospital for three days longer (95% CI 2.3 to 3.7 days). Significantly higher mortality, endoscopy and surgery rates were found in patients with UC compared with CD (p<0.05), but no significant difference in length of stay or median hospital charge between the two groups was seen. CONCLUSIONS: C difficile colitis is associated with a significant healthcare burden in hospitalised patients with IBD and carries a higher mortality than in patients with C difficile without underlying IBD.

Mucosal T-cell immunoregulation varies in early and late inflammatory bowel disease.

BACKGROUND AND AIMS: Crohn's disease is a life-long form of inflammatory bowel disease (IBD) mediated by mucosal immune abnormalities. Understanding of the pathogenesis is limited because it is based on data from adults with chronic Crohn's disease. We investigated mucosal T-cell immunoregulatory events in children with early Crohn's disease. METHODS: Mucosal biopsies and T-cell clones were derived from children experiencing the first attack of Crohn's disease, children with long-standing Crohn's disease, infectious colitis, and children without gut inflammation. RESULTS: As in acute infectious colitis, interleukin (IL) 12 induced T cells from early Crohn's disease to acquire a strongly polarised T helper (Th) type 1 response characterised by high IFN-gamma production and IL12Rbeta2 chain expression. Th1 polarisation was not induced in clones from late Crohn's disease. Mucosal levels of IL12p40 and IL12Rbeta2 messenger RNA were significantly higher in children with early than late Crohn's disease. These results demonstrate that susceptibility to IL12-mediated modulation is strongly dependent on the stage of Crohn's disease. CONCLUSIONS: At the onset of Crohn's disease mucosal T cells appear to mount a typical Th1 response that resembles an acute infectious process, and is lost with progression to late Crohn's disease. This suggests that mucosal T-cell immunoregulation varies with the course of human IBD. Patients with the initial manifestations of IBD may represent an ideal population in which immunomodulation may have optimal therapeutic efficacy.

Cutaneous Crohn's disease mimicking Melkersson-Rosenthal syndrome: treatment with methotrexate.

A woman with a 5-year history of unilateral orofacial granulomatosis required repeated evaluations (including sequential colonoscopies) to establish the diagnosis of cutaneous Crohn's disease, a condition that proved responsive to low doses of oral methotrexate administered weekly. To our knowledge this is the first report describing the use of methotrexate for treatment of orofacial granulomatosis caused by underlying Crohn's disease.

Silencing of epithelial CXCL12 expression by DNA hypermethylation promotes colonic carcinoma metastasis.

Cellular metastasis is the most detrimental step in carcinoma disease progression, yet the mechanisms that regulate this process are poorly understood. CXCL12 and its receptor CXCR4 are co-expressed in several tissues and cell types throughout the body and play essential roles in development. Disruption of either gene causes embryonic lethality due to similar defects. Post-natally, CXCL12 signaling has a wide range of effects on CXCR4-expressing cells, including the directed migration of leukocytes, lymphocytes and hematopoietic stem cells. Recently, this signaling axis has also been described as an important regulator of directed carcinoma cell metastasis. We show herein that while CXCR4 expression remains consistent, constitutive colonic epithelial expression of CXCL12 is silenced by DNA hypermethylation in primary colorectal carcinomas as well as colorectal carcinoma-derived cell lines. Inhibition of DNA methyltransferase (Dnmt) enzymes with 5-aza-2'-deoxycytidine or genetic ablation of both Dnmt1 and Dnmt3b prevented promoter methylation and restored CXCL12 expression. Re-expression of functional, endogenous CXCL12 in colorectal carcinoma cells dramatically reduced metastatic tumor formation in mice, as well as foci formation in soft agar. Decreased metastasis was correlated with increased caspase activity in cells re-expressing CXCL12. These data constitute the unique observation that silencing CXCL12 within colonic carcinoma cells greatly enhances their metastatic potential.

Paradox of simultaneous intestinal ischaemia and hyperaemia in inflammatory bowel disease.

This review has focused on evidence regarding intestinal perfusion of inflammatory bowel disease (IBD). Basic investigation has defined an altered microvascular anatomy in the affected IBD bowel, which corresponds with diminished mucosal perfusion in the setting of chronic, long-standing inflammation. Diminished perfusion is linked to impaired wound healing, and may contribute to the continued refractory mucosal damage, which characterizes IBD. Alterations in vascular anatomy and physiology in IBD suggests additional possible mechanisms by which micro-vessels may contribute to the initiation and perpetuation of IBD. This begs the following questions: will angiogenesis within the gut lead to sustained inflammation, does the growing vasculature generate factors that transform the surrounding tissue and does angiogenesis generate vascular anastomosis within the gut, with shunting of blood away from the mucosal surface, impairment of metabolism and potentiation of gut damage? Further studies are required to define the mechanisms that underlie the vascular dysfunction and its role in pathophysiology of IBD.

Radiation induced small bowel "web" formation is associated with acquired microvascular dysfunction.

BACKGROUND AND AIMS: Radiation therapy of abdominal and pelvic solid tumours results in late intestinal toxicity of a severe nature in approximately 5% of cases. These manifestations may include ischaemia and stricture formation, which may present as "webs". These webs are likely to play a role in the pathogenesis of recurrent bowel obstruction. The mechanisms of microvascular injury to the bowel in the setting of radiation have not been defined. We hypothesised that microvascular dysfunction with impaired vasodilation to acetylcholine (Ach) would be an acquired pathophysiological abnormality in radiation and "web" formation. METHODS: A 40 year old patient treated with radiation, two years previously, for an anal squamous cell cancer presented with recurrent small bowel obstruction. "Webs" in the distal ileum were detected using wireless capsule endoscopy, after small bowel barium radiographs failed to demonstrate a lesion. Following resection, freshly isolated 50-150 mum diameter arterioles from the "web" and adjacent normal calibre bowel were analysed with histology and microvessel physiological studies. RESULTS: After constriction (30-50%) with endothelin, dilation to graded doses of Ach (10(-9)-10(-4) M) was observed in vessels dissected from the stricture and the adjacent normal calibre area. Ach dilation was reduced in vessels from "web" (mean diameter 7 (2)%; n = 3, p < 0.01) compared with the adjacent unaffected bowel (mean diameter 85 (5)%). Dihydroethidine and dichlorofluorescein diacetate intravital staining demonstrated increased reactive oxygen species production in microvessels from "web" compared with adjacent normal calibre bowel. Histology from the strictured bowel demonstrated narrowing of the arterial lumen due to intimal and muscularis propria fibrosis, with endothelial preservation. CONCLUSIONS: External radiation is associated with acquired microvascular endothelial dysfunction and "web" formation in the small bowel.

Polypharmacy and Crohn's disease.

BACKGROUND: Polypharmacy has not been defined for Crohn's disease. AIMS: To determine the prevalence of polypharmacy, factors associated with polypharmacy, and consequences of polypharmacy in a Crohn's disease population. METHODS: A review of 291 Crohn's disease patients was performed. Polypharmacy was defined as either minor (two to four medications) or major (> or = 5 medications). Clinical status was evaluated with the Harvey-Bradshaw index of disease activity (HBI) and the short inflammatory bowel disease questionnaire (SIBDQ). RESULTS: Major polypharmacy was identified in 50% of patients. Crohn's disease patients on less than two medications at the intake visit had an HBI of 3.6 compared with 5.4 and 6.0 in the minor and major polypharmacy groups (P < 0.05). Similarly, patients on less than two medications had an SIBDQ of 60.3 compared with 55.7 and 53.4 in the minor and major polypharmacy groups (P = 0.11). Predictors of polypharmacy included age > 40 years (OR 1.9), duration of disease > 10 years (OR 2.0), and female sex (OR 2.5). CONCLUSIONS: Polypharmacy is common in Crohn's disease and correlates with increased disease activity and decreased quality of life. Increasing age, increasing duration of disease, and female sex are associated with major polypharmacy. These findings emphasize the need for improved treatment algorithms to optimize Crohn's disease patient management.

Intentional infliximab use during pregnancy for induction or maintenance of remission in Crohn's disease.

AIM: To study the effects of infliximab on pregnancy and foetal outcome. METHODS: We conducted a retrospective chart review of women with Crohn's disease treated intentionally with infliximab during pregnancy. The primary outcome measure was the occurrence of congenital malformations. Secondary outcome measures were the rate of premature birth, low-birth weight, small for gestational age infants, intrauterine growth retardation and caesarean section. RESULTS: Ten women were identified. Eight women received maintenance infliximab infusions throughout their pregnancy and two women received their initial infliximab infusions during pregnancy. All 10 pregnancies ended in live births. No infants had congenital malformations, intrauterine growth retardation or small for gestational age parameters. Three infants were premature and one had low-birth weight. Eight women had a caesarean section. CONCLUSIONS: This is the first reported series of intentional infliximab use throughout pregnancy. These data, combined with other studies of inadvertent use of infliximab during pregnancy, suggest that the benefits of infliximab in achieving response and maintaining remission in mothers with Crohn's disease may outweigh the risk to the foetus of exposure to the drug. Further prospective data collection will be helpful to confirm these findings.

Feasibility and safety of endoscopic evaluation of gastric emptying.

BACKGROUND AND STUDY AIMS: Scintigraphy is the currently accepted method for evaluation of gastric emptying. Although quantitative, this method is complicated, time-consuming, and costly. If a simple endoscopic technique was available for those instances when quantification of an emptying abnormality is not needed, the same clinical information could be obtained in less time and with resource savings. Our aims in this study were therefore to assess the technical feasibility, tolerability, and safety of unsedated transnasal esophagogastroscopy (T-EG) as a technique for qualitative assessment of gastric emptying. METHODS: The study was done in two phases. In the first phase, 18 volunteers (ten men, eight women) underwent T-EG at 4 hours, 5 hours, or 6 hours after ingestion of a standard meal used for scintigraphic evaluation of gastric emptying without radiolabeling. In the second phase, ten volunteers underwent T-EG after scintigraphic imaging had demonstrated complete gastric emptying. RESULTS: Subjects in both phases tolerated the procedure well and completed the study. In the first phase, 13 of 15 volunteers exhibited complete gastric emptying at 6 hours (87%), while two (13%) revealed some particulate matter in the stomach at that time. In the second phase, one of the ten volunteers exhibited a small amount of solid food residue in the stomach despite documentation of scintigraphic complete emptying. CONCLUSIONS: Evaluation of gastric emptying by unsedated T-EG is both feasible and safe. In healthy, asymptomatic individuals, complete gastric emptying of solid food may take as long as 6 hours.

Terminal ileum resection is associated with higher plasma homocysteine levels in Crohn's disease.

BACKGROUND: Elevated plasma total homocysteine (tHcy) is associated with a higher risk of thrombosis. Crohn's disease (CD) is associated with hypercoagulability of undefined etiology. We investigated tHcy in patients with CD and its relationship with vitamin status, disease activity, location, duration, and history of terminal ileum (TI) resection. STUDY: We examined fasting plasma tHcy, folate, serum vitamin B12 levels, and sedimentation rate in consecutive adult patients with CD. Harvey-Bradshaw index of CD activity and history of TI resection and thromboembolism were recorded. RESULTS: Median plasma tHcy was 10.2 micromol/L in 125 patients with CD. Men (n = 60) had higher plasma tHcy than women (n = 65) (11.2 vs. 9.1 micromol/L; p = 0.004). Patients with a history of TI resection showed lower serum B12 levels (293 vs. 503 pg/mL; p < 0.001) and higher plasma tHcy levels (11.0 vs. 9.35 micromol/L; p = 0.027) than patients without such history. Multivariate analysis showed history of TI resection, serum B12, and creatinine levels to be significant predictors of elevated plasma tHcy. Fourteen patients with CD with a history of thrombosis had an elevated median plasma tHcy of 11.6 micromol/L. CONCLUSIONS: Terminal ileum resection contributes to elevated plasma tHcy levels in CD cases. We recommend tHcy screening in patients with CD, especially in those with prior history of TI resection, and the initiation of vitamin supplementation when appropriate.

Successful desensitization and therapeutic use of infliximab in adult and pediatric Crohn's disease patients with prior anaphylactic reaction.

Infusion of the antitumor necrosis factor-alpha chimeric monoclonal antibody infliximab is highly effective in the treatment of refractory and fistulizing Crohn's disease (CD), but can be associated with the development of severe allergic reactions during retreatment, precluding further use of the medication. We present two CD patients (one adult and one child) with a history of anaphylactic/anaphylactoid reactions to retreatment with infliximab who subsequently underwent successful desensitization and therapeutic infusion using parenteral dose escalation in an intensive care unit setting.

Integrin alpha E(CD103)beta 7 mediates adhesion to intestinal microvascular endothelial cell lines via an E-cadherin-independent interaction.

Integrins are important for T cell interactions with endothelial cells. Because the integrin alpha(E)beta(7) is expressed on some circulating gut-homing T cells and as T cell numbers are reduced in the intestinal lamina propria of alpha(E)-deficient mice, we evaluated whether alpha(E)beta(7) mediates binding to intestinal endothelial cells. We found that anti-alpha(E)beta(7) mAbs partially blocked the binding of cultured intraepithelial T cells to human intestinal microvascular endothelial cells (HIMEC). Furthermore, alpha(E)beta(7)-transfected K562 cells bound more efficiently than vector-transfected K562 cells to HIMEC. Finally, HIMEC bound directly to an alpha(E)beta(7)-Fc fusion protein. These interactions were partially blocked by anti-alpha(E)beta(7) mAbs, and endothelial cell binding to the alpha(E)beta(7)-Fc was dependent upon the metal ion-dependent adhesion site within the alpha(E) A domain. Of note, the HIMEC lacked expression of E-cadherin, the only known alpha(E)beta(7) counterreceptor as assessed by functional studies, flow cytometry, and RT-PCR. Thus, HIMEC/alpha(E)beta(7) binding was independent of E-cadherin. In addition, this interaction appeared to be tissue selective, as HIMEC bound to the alpha(E)beta(7)-Fc, whereas microvascular endothelial cells from the skin did not. Finally, there was evidence for an alpha(E)beta(7) ligand on intestinal endothelial cells in vivo, as alpha(E)beta(7) expression enhanced lymphocyte binding around vessels in the lamina propria in tissue sections. Thus, we have defined a novel interaction for alpha(E)beta(7) at a nonepithelial location. These studies suggest a role for alpha(E)beta(7) in interactions with the intestinal endothelium that may have implications for intestinal T cell homing or functional responses.

Prolonged duration of response to infliximab in early but not late pediatric Crohn's disease.

OBJECTIVES: Tumor necrosis factor-alpha plays a central role in chronic intestinal inflammation of Crohn's disease. Targeting this cytokine with the chimeric monoclonal antibody infliximab has emerged as an effective form of therapy in adult Crohn's disease patients. We sought to determine whether infliximab treatment would benefit pediatric patients with medically refractory Crohn's disease. We also assessed the duration of response, comparing children with early disease to children with long-standing (late) Crohn's disease. METHODS: Fifteen consecutive children (mean age 12.8 +/- 3.2 yr) with medically refractory Crohn's disease were enrolled in a prospective, open-label trial of a single, 5-mg/kg infliximab intravenous infusion. Medically refractory disease was defined as an inability to taper steroids, lack of response to immunomodulator therapy over 4 months, and active disease as measured by the Pediatric Crohn's Disease Activity Index (PCDAI). Primary endpoints included measurements of disease activity (PCDAI), steroid use, and duration of clinical response. RESULTS: In all, 14/15 children (94%) improved after infliximab infusion, with a significant decrease of both PCDAI and daily steroid use by 4 wk. Ten patients (67%) achieved complete remission by 10 wk. Among the 14 patients who responded, three of six children (50%) with early disease maintained clinical response through the 12-month trial period, compared to none of eight children with late disease. There were no serious complications associated with the use of infliximab in any of the patients. CONCLUSIONS: Infliximab is safe and effective in the short-term treatment of medically refractory pediatric Crohn's disease. More importantly, there is a remarkably prolonged duration of response after infliximab therapy in children with early compared to late Crohn's disease.

Deficient iNOS in inflammatory bowel disease intestinal microvascular endothelial cells results in increased leukocyte adhesion.

Microvascular endothelial cells play a key role in inflammation by undergoing activation and recruiting circulating immune cells into tissues and foci of inflammation, an early and rate-limiting step in the inflammatory process. We have previously [Binion et al., Gastroenterology112:1898-1907, 1997] shown that human intestinal microvascular endothelial cells (HIMEC) isolated from surgically resected inflammatory bowel disease (IBD) patient tissue demonstrate significantly increased leukocyte binding in vitro compared to normal HIMEC. Our studies [Binion et al., Am. J. Physiol.275 (Gastrointest. Liver Physiol. 38):G592-G603, 1998] have also demonstrated that nitric oxide (NO) production by inducible nitric oxide synthase (iNOS) normally plays a key role in downregulating HIMEC activation and leukocyte adhesion. Using primary cultures of HIMEC derived from normal and IBD patient tissues, we sought to determine whether alterations in iNOS-derived NO production underlies leukocyte hyperadhesion in IBD. Both nonselective (N(G)-monomethyl-L-arginine) and specific (N-Iminoethyl-L-lysine) inhibitors of iNOS significantly increased leukocyte binding by normal HIMEC activated with cytokines and lipopolysaccharide (LPS), but had no effect on leukocyte adhesion by similarly activated IBD HIMEC. When compared to normal HIMEC, IBD endothelial cells had significantly decreased levels of iNOS mRNA, protein, and NO production following activation. Addition of exogenous NO by co-culture with normal HIMEC or by pharmacologic delivery with the long-acting NO donor detaNONOate restored a normal leukocyte binding pattern in the IBD HIMEC. These data suggest that loss of iNOS expression is a feature of chronically inflamed microvascular endothelial cells, which leads to enhanced leukocyte binding, potentially contributing to chronic, destructive inflammation in IBD.