BACKGROUND: Mycobacterium avium subspecies paratuberculosis (MAP) has been suggested as a causative agent of Crohn's disease (CD). Despite a long-term debate to prove this possibility, the role of this bacterium in the pathogenesis of CD is still a subject of controversy. The objective of the study was to develop a serodiagnostic assay for the diagnosis of CD in humans. METHODS: In the present study, five different ELISA assays were accessed: 1) IDEXX, a commercially available kit for the diagnosis of Johne's disease in ruminants; 2) an in-house developed assay based on total MAP cytoplasmic proteins, and three other assays based on recombinant MAP recombinant antigens a) a 23 kDa antigen, pB11/B7, b) a 35 kDa antigen, P35 and c) a 36 kDa antigen, P36. The last three proteins were identified from an expression genomic library of MAP that was constructed in our laboratory. A total of 43 sera samples were analyzed in this study, which included 14 CD patients, 14 Ulcerative Colitis (UC) patients, and 13 non-inflammatory bowl disease (IBD) patients. lmmunoblot and silver stain analyses were performed to confirm protein identity and purity. ELISA was developed and used to analyze the level of anti-MAP lgG antibodies in sera from patients. RES UL TS: The rate of positive ELISA results is based on previously published interpretation criteria. ELISA results using the IDEXX kit showed 12/14 (85.7%) positive for CD as compared to 7/13 (53.8%) for non-lBD and 6/14 (42.9%) for uc.· 8/14 (57.1%) of the CD sera were positive with the ELISA results based on MAP cytoplasmic proteins compared with 6/13 (46.2%) of non-lBD and 10/14 (71.4%) of UC. Further analyzing the recombinant proteins, when two out of three assays were used 12/14 (85.7%) CD (P<0.05), 0/13 (0.0%) non-lBD, and 1/14 (7.7 %) UC were positive. Moreover, when all three recombinant proteins are utilized for analysis, the specificity of the test greatly increased, giving 13/14 (92.9%) positive for CD, 3/14 (21.4%) for UC and 2/14 (14.3%) for non-lBD. CONCLUSION: MAP recombinant proteins, pB11/B7, p35, and p36 showed a strong reactivity with diagnosed CD patients while excluding healthy individuals and other IBD patients. In addition, they served as a great tool to distinguish between CD and UC patients. A larger sample size needs to be tested, none the less this data strengthens the role of MAP in CD etiology and suggests a great potential for using the recombinant-based assays for diagnosis and treatment monitoring of patients with inflammatory bowel disease.

Crohn's Disease (CD) is a debilitating condition characterised by chronic intermittent intestinal inflammation. More than 90 genetic polymorphisms are associated with CD susceptibility, including several in genes of the innate immune system. Here I present a series of experiments designed to enhance our knowledge of the roles of CD-associated polymorphisms in pathogenesis. Many therapeutic regimens are employed in CD treatment, but patients' responses to treatment and disease progression vary widely. There is great interest in studying whether analysis of patients' genotype at CD-associated polymorphisms can be used to predict their disease course, and guide clinical decision-making. To answer these questions, it is essential to be able routinely and cost- effectively to genotype patients at the full range of known CD-associated polymorphisms. The first project presented here describes the design and initial successful testing of a CD-specific genotyping microarray for use in genotype-phenotype studies. The polymorphism most strongly associated with CD susceptibility is in the pattern recognition receptor NOD2; the remaining experiments presented here study the function of NOD2 in primary human monocyte-derived Dendritic Cells (DCs). First, a microarray study is presented which characterises global transcriptional responses to NOD2 stimulation in DCs. NOD2 stimulation is shown to enhance transcriptional changes induced by Toll-Like Receptor 2 stimulation, and NOD2-mediated transcriptional regulation is shown to be lost in DCs expressing CD-associated NOD2 variants. Second, experiments are presented which describe development of a new protocol for proteomic analysis of post-translational protein modifications, and which identify a number of novel candidate targets of NOD2 signalling in DCs. Finally, a project is presented which demonstrates for the first time that NOD2 stimulation induces autophagy in DCs, in an NF-kB and RIPK2-dependent pathway. CD-associated polymorphisms in NOD2 and ATG 16Ll abolish NOD2-mediated autophagy induction, resulting in impaired bacterial handling and antigen presentation.

NOD2 is an intracellular innate immune receptor expressed in dendritic cells and gastrointestinal epithelial cells. Polymorphisms in the NOD2 gene convey a strong predisposition to Crohn’s disease (CD), a form of inflammatory bowel disease. Understanding the function of NOD2, and in what way it is aberrant in the presence of NOD2 polymorphisms, would confer a valuable paradigm for understanding Crohn’s pathogenesis. CD is thought to arise both from defects in the gut mucosal barrier and from a dysregulated Th17 immune response to commensal gut flora. Aberrant expression of IL-23 is present in both human CD and in murine models of colitis. Wild-type NOD2 contributes to NFκB activation and pro-inflammatory cytokine production on recognition of its cognate ligand, a function that is lost in CD-associated mutations. How the predominantly loss-of-function CD-NOD2 contributes to the pro-inflammatory response present in Crohn’s is not yet understood. In this thesis a set of experiments is described that aim to shed light on the function of NOD2, firstly through identification of negative regulators of immune activation that are dependent on NOD2 for their expression. This work identifies the microRNAs that are expressed following NOD2 triggering in human dendritic cells. Specifically, up-regulation of the miR-29 family was found to be dependent on wild-type NOD2 function. A number of novel miR-29 targets and their functional consequences are presented, including the cytokine subunits IL-12p40 and IL-23p19, directly linking NOD2 polymorphisms and aberrant IL-23 expression. Secondly, a project aiming to identify components of the NOD2 signalling complex (or signalosome) is described. To this end I employed a model system that involved tagging NOD2, and stable expression in a human cell line. These clones were validated for expression and function before an immunoprecipitation protocol was optimised. Mass spectrometry analysis of these samples identified the known NOD2-interacting protein Erbin.

The inflammatory bowel diseases (IBDs) are a group of chronic conditions affecting the gastrointestinal tract, often presenting with non-specific clinical features such as abdominal pain, weight loss and diarrhoea. Approximately 25% of patients are diagnosed with IBD in childhood. For epidemiological studies, previously collected (1990-1995) and original (2003-2008) Scottish incidence data were used to determine national trends in newly diagnosed paediatric IBD (PIBD). A smaller, geographically defined, prospective 14-year cohort (1997- 2011) in South-East Scotland (SES) was used to assess regional trends in incidence, point prevalence, disease extent, medication use and PIBD surgery rates in 326 children. For the detailed analysis of the role of ICOSLG and CRP in Scottish children with PIBD, haplotype-tagging of both genes in 448 children (and their parents) registered on the Paediatric Inflammatory bowel disease Cohort and Treatment Study (PICTS) database was performed. Further clinical information from this database and previously gathered adult mRNA microarray data were also used to inform the analysis. For the faecal calprotectin (FC) case-control study, all PIBD patients diagnosed in SES between 01.01.05 and 31.12.10 (aged 1- 17yrs) with a FC performed during initial workup were identified; controls were matched non- IBD patients who had similarly undergone endoscopy with a referral FC level available. The systematic review and meta-analysis of FC case-control studies was performed with keywords relating to IBD and calprotectin in electronic resources from 1946 to May 2012. Inclusion criteria were studies that reported FC levels prior to the endoscopic investigation of IBD in children less than 18 years old. Laboratory work used newly derived HEK293 and HCT116 cell lines stably expressing wild-type NOD2 and the CD-associated NOD2 frameshift mutant, as well as utilising previously derived HEK293 and HCT116 cells stably expressing green fluorescent-labelled protein LC3 during the assessment of autophagy. Western blot, immunofluorescent microscopy and flow cytometry were used for analysis. There was a significant rise in PIBD incidence in Scotland since the early 1990s, with 260 new cases between 1990-1995 (4.45/100,000/year) and 436 in the 2003-2008 epoch (7.82/100,000/year) (p<0.001). A five-fold increase in Crohn's disease (CD) in the last 40 years was also demonstrated. SES was shown to have the highest recorded PIBD incidence rate in the UK for the six-year epoch from 2006-2011 (9.50/100,000/year) with a significant rise in ulcerative colitis (UC) to 2.67/100,000/year (p=0.010). Point prevalence rates for PIBD in SES had also risen significantly to 41.2/100,000 between the 2000-2005 and 2006-2011 epochs (p=0.016). With a follow up of 1577 patient years, the severe phenotype in children with PIBD was confirmed; 34% of children with CD presented with pan-enteric disease (44% at follow up), and 76% of children with UC had pancolonic disease at diagnosis (81% at follow up). 26% of patients required methotrexate and 18% were exposed to infliximab/adalimumab, with the time to first exposure of both significantly lower in children diagnosed between 2006-2011 (p=0.001 and p<0.001 respectively). A total of 70% of children were exposed to azathioprine and 20% underwent IBD-related surgery. Using a haplotype-tagging approach and transmission disequilibrium testing (TDT) in 230 PIBD case-parent trios there was significant overtransmission of the rs8126734-A single nucleotide polymorphism (SNP) in ICOSLG following correction (p=0.0467). In the CD TDT analysis the same SNP was overtransmitted (p=0.0084). The strongest susceptibility signal was evident across the two marker haplotype rs762421-A / rs8126734-G (p=0.0072), suggesting that the 3-prime untranslated region in ICOSLG may be targeted for deep sequencing. mRNA microarray data from adult patients showed downregulation of ICOSLG expression in the ascending colon (p=0.023) and upregulation in the descending colon (p=0.0351) in uninflamed biopsies from CD patients and non-IBD controls; no difference in gene expression was shown in UC patients. Using a similar approach, the A allele of two SNPs tagging CRP showed significant over-transmission to affected IBD patients after correction (rs1417938, p=0.006; rs1130864, p=0.015). The six-marker haplotype (ACACAC) showed significant distortion of transmission to affected individuals (p=8x10-4). CD and UC patients demonstrated differences in rs1205 genotype (p=0.0085) and CRP haplotype (p=0.0024), with the influence of the rs1205 SNP on response to anti-tumour necrosis factor-alpha therapy also shown (p=0.021). During the FC case-control study significantly elevated FC levels at diagnosis were demonstrated compared to controls (1265 μg/g vs 65 μg/g; p<0.001). FC also outperformed commonly used blood parameters (e.g. CRP, ESR, platelets), with an area under the curve of 0.93 (95% CI 0.89-0.97) and good sensitivity (0.93 [95% CI 0.86-0.98]) and specificity (0.74 [95% CI 0.64-0.82]) when values above 200μg/g were used. FC levels were not influenced by disease location in CD or UC. The systematic review and meta-analysis highlighted the often poor methodological quality of previous studies and concluded that across all studies FC had a pooled sensitivity of 0.98 (95% CI 0.95-1.00) and pooled specificity of 0.68 (95% CI 0.50-0.86) for PIBD at diagnosis. Characterisation of cells stably-expressing wild-type NOD2 or the CD-associated NOD2 frameshift mutation demonstrated increased cell proliferation compared to empty vector, and an accentuated apoptotic response to serum starvation. The NOD2 frameshift protein had a shorter half-life (at 11 hours) than the wild-type protein, with degradation of the NOD2 protein shown to be mediated through a proteasome-dependent pathway, possibly through lysine residues on the CARD domain. Following the establishment of a robust method of assessing autophagy in a cell culture system, experimental work showed that muramyl dipeptide-induced autophagy is unlikely to signal through the mammalian target of rapamycin, with the intermediate filament vimentin shown to be intimately involved in this pathway; the vimentin gene (Vim) was also shown to be a candidate susceptibility gene for CD. Using a panel of PIBD drugs azathioprine was shown to induce autophagy in a dose-dependent manner through an mTOR-dependent, ERK-independent pathway. It can be seen that with the increasing incidence and prevalence of PIBD in Scotland that a greater understanding of epidemiological trends, the role of genetic susceptibility, the optimal use of biomarkers and translational functional biology are all needed to understand further the aetiopathogenesis of PIBD. This future work will undoubtedly help to inform service design and the clinical care pathways utilised to provide the best care for children in addition to targeting pathways for potential drug development, with these measures helping to prepare for the increasing disease burden generated by PIBD.

The two options for treatment of the inflammatory bowel disease Crohn’s Disease are surgery and pharmacotherapy. Pharmacotherapy with the goal of inducing and maintaining remission is the preferred treatment route, but the current medications are not entirely effective in achieving these goals. Approximately half of Crohn’s Disease patients will be required to have surgical bowel resection within 20 years of diagnosis, and many patients are at higher risk of adverse events such as cancer, either directly as a result of Crohn’s Disease or due to side-effects of the drugs used to treat the condition. Medical management of the disease is very complicated and there is a relative lack of uniformity in treatment. Different drugs used either in monotherapy, sequential therapy, or combination therapy produce differing levels of efficacy and different outcomes. This analysis provides an overview of the four major classes of drugs used in the treatment of Crohn’s Disease and a discussion of the overall efficacy of the different methods of treatment. While more studies need to be conducted into the differing outcomes of monotherapy, sequential therapy, and combination therapy, it appears as though any treatment involving the use of biologics such as tumor necrosis factor alpha (TNF-alpha) inhibitors results in improved outcomes relative to treatment styles that lack the use of biologics.

BACKGROUND: During the mid to late 20th century, parts of Europe and North America began experiencing increasing incidence of inflammatory bowel disease for unknown reasons. Epidemiological studies carried out at the time determined that incidence rates and disease severity were higher in the northern latitudes than in the southern latitudes. LITERATURE REVIEW: In the ensuing years, an inverse association was established between ultraviolet radiation and incidence of Crohn’s disease, a finding that has not proven to be as robust for ulcerative colitis. This association was explored further and vitamin D was implicated to be the factor of ultraviolet radiation which was associated with increased incidence. Currently, all evidence implicating vitamin D in the pathogenesis of Crohn’s disease comes from epidemiological, animal, and in vitro studies, providing strong evidence for an association, but none of which can prove causality. Causality must be proven in prospective clinical trials, which, at present, have come up short in providing statistically significant findings. METHODS: The proposed trial outlined below provides a method of studying the question at hand in a way that has not been previously studied. This is a randomized, double blind, controlled trial which assesses the effect of supplementation of vitamin D in patients with active Crohn’s disease. DISCUSSION: Acceptance of the alternative hypothesis would be a big step forward in the management of Crohn’s disease. It would have wide-ranging implications, resulting in decreased healthcare costs, decreased use of toxic medications, and increased quality of life.

Background: Not only does IBD lead to nutritional deficiencies, but also nutrients influence its pathophysiology: exclusive enteral nutrition (EEN) is an effective primary treatment in Crohn's disease; and vitamin D (VitD) is involved in its pathogenesis and course. Aims: We hypothesised that nutrients impact on the course of IBD. We therefore studied the effect of EEN i) on long term clinical course in children; ii) on CD58, a costimulatory molecule at the intestinal epithelial cell (IEC) lines, iii) adults with Crohn's disease. We examined the possible effect of serum vitamin D levels on the course of IBD and also the possible role of ethnicity in our paediatric and adult populations that were treated with EEN but also in our general adult population. Results Chapter II: 56 paediatric patients with Crohn's disesase were followed up for 5 years. 57% of patients achieved remission after 6 weeks of EEN. Achievement of clinical remission within 6 weeks of EEN was significantly associated with a longer time to relapse and to treatment escalation. VitD deficiency was common; and those patients who were deficient were significantly more likely to require corticosteroids and also needed thiopurines sooner. Chapter III: CD58 was expressed in the IEC isolated from IBD patients and healthy controls. EN down-regulated the expression of CD58 on IEC lines. Chapter IV: 22 adult patients with Crohn's disease with a mean age of 30.8 years were given EEN and followed up for a mean time of 1.9 years. 22.7% of patients went into clinical remission and 77.3% experienced a clinical response. By the end of follow up 63.6% (14/22) of patients had clinically relapsed and 36.4% required surgery during their follow up. There was no difference between South Asian and Caucasian patients in the disease outcomes after administration of EEN. Chapter V: Bangladeshis were more often vitamin D deficient than white Caucasian patients; however vitamin D status was not associated with the course of IBD. Bangladeshis developed perianal disease and required thiopurines earlier in their disease course. Bangladeshi patients with UC had more extensive disease. Conclusions: EEN, when successful, improves the long term outcome of Crohn's disease in children, possibly in part, by down-regulating CD58 on the IEC. VitD deficiency may influence the clinical course of IBD; however our results were contradictory between children and adults and significantly limited by the assessment of the vitamin D level at a single time point.

La maladie de Crohn (MC) est une maladie inflammatoire chronique de l’intestin (MICI), dont la physiopathologie résulterait d’une interaction anormale entre le microbiote intestinal et le système immunitaire de l’hôte sous l’influence de facteurs génétiques et environnementaux. Au sein de ce microbiote, les E. coli adhérents et invasifs (AIEC) colonisent la muqueuse iléale des patients atteints de la MC et sont capables de survivre et se multiplier à l’intérieur des macrophages. Par ailleurs, les objectifs thérapeutiques de la MC et notamment la cicatrisation muqueuse endoscopique nécessitent des endoscopies répétées, peu acceptables du point de vue des patients. Parmi les moyens alternatifs, la calprotectine fécale est le marqueur fécal de référence même si ses performances semblent diminuées dans certaines situations comme la maladie iléale pure. Le premier objectif de ces travaux étaient de comparer la capacité des macrophages dérivés de monocytes (MDM) issus de patients atteints de MC, de rectocolite hémorragique (RCH) ou de sujets sains à contrôler l’infection par les AIEC et d’identifier les facteurs associés à cette multiplication des AIEC et notamment le rôle des polymorphismes génétiques associés à la MC en lien avec l’autophagie. Les AIEC se multipliaient de manière plus importante que la souche non pathogène K12 dans les macrophages quel que soit leur origine. L’entrée des AIEC (1h post- infection) ne variait pas en fonction de la provenance des macrophages. La survie des AIEC était augmentée dans les MDM issus de patients MC comparés à ceux issus de RCH ou de sujets contrôles. En analyse multivariée, cette survie était positivement corrélée à la sécrétion d’IL1β mais était diminuée en présence des variants à risque pour ULK1 (p=0,046) et XBP1 (p=0,014). Les MDM issus de patients MC étaient incapable de contrôler la multiplication des AIEC contrairement à ceux issus de RCH ou de sujets contrôles d’autant plus en présence du variant à risque pour IRGM (p=0,045). L’infection des MDM de patients MC par les bactéries AIEC induit un profil de sécrétion cytokinique pro-inflammatoire. La deuxième partie de ces travaux avait pour but de comparer les performances de la chitinase 3-like 1 fécale (CHI3L1), une protéine de l’hôte interagissant avec un facteur de virulence des AIEC, et la métalloprotéase matricielle 9 (MMP-9) pour détecter l’activité inflammatoire endoscopique de la MC en comparaison du marqueur fécal de référence, la calprotectine. Les taux de CHI3L1, de MMP-9 et de calprotectine fécales étaient corrélés au ‘Crohn’s Disease Endoscopic Index of Severity’ (CDEIS) et étaient significativement augmentés en présence d’ulcérations endoscopiques. En cas d’atteinte iléale pure, la CHI3L1 fécale semblait mieux corrélée au CDEIS que la calprotectine fécale. Le seuil de CHI3L1 fécale de 15 ng/g présentait de meilleures performances que la calprotectine fécale pour détecter la présence d’ulcérations endoscopiques. La MMP-9 étaient un marqueur performant pour détecter la présence de lésions endoscopiques dans les MICI. En conclusion, nous avons montré qu’il existe un défaut des macrophages à contrôler l’infection par les bactéries AIEC chez les patients atteints de MC en rapport avec les variants à risque impliqués dans l’autophagie conduisant à un phénotype de macrophages pro-inflammatoires. La CHI3L1 fécale, connue comme une protéine de l’hôte interagissant avec un facteur de virulence des AIEC, tout comme la MMP-9 semblent être de bons marqueurs d’activité endoscopique dans les MICI. / Crohn's disease (CD) is a chronic inflammatory bowel disease (IBD) whose pathophysiology results from an abnormal interaction between the gut microbiota and the host's immune system under the influence of genetic and environmental factors. . Within this microbiota, adherent and invasive E. coli (AIEC) colonize the ileal mucosa of patients with CD and are able to survive and multiply within macrophages. Moreover, the therapeutic objectives of CD, and especially endoscopic mucosal healing, require repeated endoscopies, which are not acceptable from the patients' point of view. Among alternative means, fecal calprotectin is the fecal marker of reference even if its performance seems to be diminished in certain situations like pure ileal disease. The primary objective of this work was to compare the ability of monocyte-derived macrophages (MDM) from patients with CD, ulcerative colitis (UC) or healthy subjects to control AIEC infection and to identify associated with this multiplication of AIEC and in particular the role of genetic polymorphisms associated with CD in connection with autophagy. AIEC multiplied more than non-pathogenic strain K12 in macrophages irrespective of their origin. The entry of the AIEC (1h post-infection) did not vary according to the origin of the macrophages. The survival of AIEC was increased in MDM from MC patients compared to those from HCR or control subjects. In multivariate analysis, this survival was positively correlated with the secretion of IL1β but was decreased in the presence of the variants at risk for ULK1 (p = 0.046) and XBP1 (p = 0.014). MDM from MC patients were unable to control the multiplication of AIEC, unlike those from HCR or control subjects, especially in the presence of the variant at risk for IRGM (p = 0.045). Infection of MDM from MC patients by AIEC bacteria induces a pro-inflammatory cytokine secretion pattern. The second part of this work aimed to compare the performance of faecal chitinase 3-like 1 (CHI3L1), a host protein interacting with AIEC virulence factor, and matrix metalloprotease 9 (MMP-9). to detect the endoscopic inflammatory activity of MC in comparison with the standard fecal marker, calprotectin. Fecal CHI3L1, MMP-9 and calprotectin levels were correlated with Crohn's Disease Endoscopic Index of Severity (CDEIS) and were significantly increased in the presence of endoscopic ulcerations. In case of pure ileal involvement, fecal CHI3L1 seemed better correlated with CDEIS than fecal calprotectin. The fecal CHI3L1 threshold of 15 ng / g showed better performance than faecal calprotectin in detecting the presence of endoscopic ulcerations. MMP-9 was a powerful marker for detecting the presence of endoscopic lesions in IBD. In conclusion, we have shown that there is a macrophage defect to control infection by AIEC bacteria in patients with CD related to atopic risk variants involved in autophagy leading to a pro-inflammatory macrophage phenotype . Fecal CHI3L1, known as a host protein interacting with AIEC virulence factor, as well as MMP-9 appear to be good markers of endoscopic activity in IBD.

The three thiopurine drugs azathioprine (AZA), 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG) are used to treat several diseases, including inflammatory bowel disease (IBD). They are pro-drugs and are believed to act through the formation of thioguanine nucleotides (TGNs). Other important metabolites are the methylthioinosine nucleotides (meTINs). These metabolites are active in the white blood cells (WBCs).Most patients respond well to the thiopurine drugs but up to a third have to modify or discontinue their treatment due to adverse events or a lack of therapeutic effects. This could be caused by inter-patient variability in the metabolism of the drugs. Therapeutic drug monitoring (TDM) of thiopurine nucleotides in red blood cells (RBCs) is used to guide treatment. Current routine assays measure the nucleotides after hydrolysation to nucleic bases and are therefore unable to distinguish between mono-, di-, and triphosphates. Recently it was shown that these assays failed to predict the clinical outcome in about 40% of the patients. It has been suggested that measuring thioguanosine triphosphate (TGTP) (believed to be the most active of the TGNs) separately might increase the clinical value.An assay suitable for measuring thioguanosine mono- (TGMP) and diphosphate (TGDP) and TGTP, as well as methylthioinosine mono- (meTIMP), di- (meTIDP) and triphosphate (meTITP) separately in RBCs in clinical samples has been developed. In clinical studies of 82 IBD patients, we found no correlation between the thiopurine dose and metabolite levels in RBCs, thus illustrating the importance of metabolite measurements in the TDM of thiopurines.The TGN peak measured by the routine assay during TDM of patients treated with thiopurines consisted of TGTP and TGDP with a small contribution from TGMP. The meTIN also consisted of mono-, di- and triphosphates, but in different proportions, indicating differences in the formation. The inter-individual differences in nucleotide distribution were very small and a strong correlation between the different nucleotides and their respective sums was observed. As a consequence, measuring the mono-, di- and triphosphates separately was not beneficial in predicting remission, which was confirmed by the results from the clinical study.Further research into the metabolism and mode of action of thiopurine drugs is needed to understand the inter-patient variability in response and metabolite formation. An assay suitable for such studies, measuring TGNs and meTINs in cultured cells, has also been developed.

This study examines the effects of TYSABRI on the health-related quality of life (HrQoL) outcomes, disease status and symptomatology, treatment satisfaction, productivity outcomes and healthcare utilization for patients with Crohn’s Disease (CD). A total of 241 patients consented to participate in the study, out of which 61 patients qualified for the baseline survey. After three-months of TYSABRI therapy, the follow-up survey was completed by 24 patients. Changes in outcome scores from baseline to the three-month follow-up were evaluated. The 24 patients with the three-month follow-up were, on average 41 years old and 62.5% percent were female. For those with follow-up, a significantly lower proportion of patients (41.7 percent) identified their CD severity as moderate to severe compared to 83.3 percent at baseline (p=0.001). The patients also reported experiencing a significantly lower mean number of CD relapses at follow-up (4.0) compared to baseline (6.8) (p=0.004). Improved median well-being scores (2.0 vs. 1.0; p<0.001) and improved median abdominal pain scores (2.0 vs. 1.0; p=0.001) were also reported at follow-up. The patient global assessment of HrQoL over the last 2 weeks was significantly improved at follow-up (2.0 vs. 3.0; p=0.006). Similar improved results were observed regarding their assessment of the impact of CD on HrQoL (7.0 vs. 5.0; p<0.001). A significant change of 32.0 points on the total Inflammatory Bowel Disease Questionnaire (IBDQ) scale (p<0.001) and significant improvements in each of the four component scales were also seen at follow-up (p≤0.05). Significant improvement was noted on the SF-36 PCS scale (mean change 7.0; p=0.001) and MCS scale (mean change 6.0; p=0.05). Significant improvements were observed in the scores for each of the four scales of the treatment satisfaction questionnaire at follow-up: effectiveness scale (28.6 vs. 63.0; p<0.001); side-effects scale (61.6 vs. 82.2; p=0.01); convenience scale (63.8 vs. 70.8; p=0.05); and global satisfaction scale (41.3 vs. 67.0; p<0.001). A significant decrease in the number of CD-related emergency room (ER) visits was observed between baseline and follow-up (1.3 vs. 0.7; p=0.03). For the productivity outcomes, the percent of planned household work lost due to absenteeism was significantly reduced (73.1 percent vs. 43.9 percent; p=0.02) and the total percent of planned hours lost was also reduced (87.3 percent vs. 64.4 percent; p=0.037). These results indicate that TYSABRI is associated with significant improvement in HrQoL outcomes, CD disease severity, treatment satisfaction, ER visits and productivity outcomes. / text