Background The inflammatory bowel diseases (IBD) ulcerative colitis (UC) and Crohn's disease (CD) are chronic relapsing inflammatory disorders which have a rising incidence and cause significant morbidity. There are currently several treatment options with many more in the drug pipeline, but there are a lack of accurate biomarkers for decisions on treatment choice, assessment of disease activity and prognostication. There is a growing interest and desire for personalised or 'precision' medicine in IBD where novel biomarkers may help individualise IBD care in terms of diagnosis, choice of therapy, monitoring of response and detection of relapse. One class of functionally active biomarkers which have yet to be thoroughly investigated in IBD is damage-associated molecular patterns (DAMPs) including mitochondrial DNA (mtDNA). It has been recently shown that gut mitochondrial dysfunction can result in loss of epithelial barrier function and the development of colitis. Mitochondrial DAMPs have recently been described as elevated in several inflammatory diseases. Hypothesis The primary hypothesis of this thesis is that circulating levels of mtDNA is elevated in IBD. Secondary hypotheses are: (a) levels of other mitochondrial DAMPs are elevated in IBD, (b) circulating mtDNA can be used as a novel biomarker in IBD and (c) mtDNA is released locally at sites of inflammation in IBD. Methods Plasma and serum were collected prospectively from recruited IBD patients and non-IBD controls. Faeces and colonic tissue were collected from a subset of these patients. mtDNA in serum, plasma and faeces was measured using qPCR (amplifying COXIII/ND2 genes). Mass spectrometry was used to detect mitochondrial formylated peptides in the plasma of a subset of patients. IBD tissue was assessed for (a) mitochondrial damage using transmission electron microscopy (TEM) and (b) TLR9 expression, the target for mtDNA. Results 97 patients with IBD (67 UC and 30 CD), and 40 non-IBD controls were recruited. Plasma mtDNA levels were increased in UC and CD (both p < 0.0001) compared to non-IBD controls; with significant correlations with blood (CRP, albumin, white cell count), clinical and endoscopic markers of severity; and disease activity. In active UC, we detected significantly higher circulating mitochondrial formylated peptides and faecal mtDNA levels (vs. non-IBD controls [p < 0.01 and < 0.0001 respectively]) with demonstrable TEM evidence of intestinal mucosal mitochondrial damage. In active IBD, TLR9+ lamina propria inflammatory cells were significantly higher in UC/CD compared to controls (both p < 0.05). Conclusions Taken together, the findings suggest mtDNA is released during active inflammation in inflammatory bowel disease and is a potential novel mechanistic biomarker.

Pathogenesis of autoimmune and auto-inflammatory diseases is induced by auto-aggressive helper T (Th) cells (i.e. Th1 and Th17 cells), and can be controlled by regulatory T cells (Tregs) characterized by expression of the transcription factor Foxp3. Thus, development of autoimmunity is regulated by the balance of Tregs and Th1/Th17 cells. Prostaglandin E₂ (PGE₂) is a bioactive lipid mediator with immune-modulatory potential that acts through 4 receptors (EP1-4). It has been shown that PGE₂ facilitates Th1 and Th17 cell development and expansion, therefore promoting autoimmune inflammation. However, the role of PGE₂ in Treg development and function is largely unclear. The aim of this PhD was to test the hypothesis that PGE₂ regulates Treg development, function and subsequent immune response. I observed that in vivo inhibition of endogenous PGE₂ biosynthesis using a COX inhibitor resulted in increased Foxp3+ Tregs in various lymphoid organs. This response was prevented by addition of an EP4 agonist. PGE₂-EP4 signalling particularly inhibits RORγt+ Tregs in the intestine. This was not observed in either antibiotic-treated mice or MyD88/TRIF double-knockout mice, suggesting gut commensal microbiota involvement. In addition, PGE₂ has a role in microbiota-dependent regulation of intestinal CD11c+MHCII+CD11b+CD103- mononuclear phagocytes (MNPs) which drive intestinal Treg expansion through production of type 1 interferons. Consistent with these in vivo observations, gut microbial metabolites from indomethacin treated mice enhanced in vitro RORγt+ Treg differentiation in the dendritic cell- T cell co-culture system. Adoptive transfer of caecal microbiota from COX inhibitor- treated mice into naïve mice also provided protective benefits in a chemical (DSS)-induced colitis disease model. In summary, this work has demonstrated that PGE₂ affects intestinal Tregs, indicating a novel mechanism for interaction of PGE₂, the adaptive immune system and the gut microbiota in homeostasis within this environment. These findings increase our understanding of the role of PGE₂ in development of inflammatory bowel disease and offer potential therapeutic strategies for treating this disease.

As Doenças inflamatórias intestinais (DII) são multifatoriais e sua etiologia envolve susceptibilidade genética, fatores ambientais, disbiose e ativação exacerbada do sistema imunológico no intestino. Essas doenças também tem sido relacionadas a baixos níveis de dehidroepiandrosterona (DHEA), um hormônio precursor de diversos esteroides e relacionado à modulação das respostas imunes. Porém, os mecanismos precisos que relacionam as ações deste hormônio com a proteção ou susceptibilidade à doença de Crohn ou colite ulcerativa ainda não são totalmente conhecidos. Sendo assim, este projeto buscou entender o papel imunomodulador do DHEA exógeno in vitro e in vivo durante a inflamação intestinal experimental induzida por dextran sulfato de sódio (DSS) em camundongos C57BL/6. Inicialmente, in vitro, DHEA inibiu a proliferação de células do baço de forma dose dependente nas concentrações de 5?M, 50?M ou 100?M, com diminuição da produção de IFN-?. Este hormônio não foi tóxico para células de linhagem mieloide, embora tenha causado necrose em leucócitos nas doses mais elevada (50 ?M e 100?M), o que pode ter influenciado a diminuição das citocinas in vitro. Nos ensaios in vivo, os camundongos tratados com DHEA (40 mg/Kg) foram avaliados na fase de indução da doença (dia 6) e durante o reparo tecidual, quando os animais expostos ao DSS e ao DHEA por 9 dias foram mantidos na ausência destas drogas até o dia 15. Houve diminuição do escore pós-morte, melhora no peso e nos sinais clínicos da inflamação intestinal, com redução de monócitos no sangue periférico com 6 dias e aumento de neutrófilos circulantes na fase de reparo tecidual (15 dias). Ainda, a suplementação com DHEA levou à redução da celularidade da lâmina própria (LP) e ao restabelecimento do comprimento normal do intestino. O uso deste hormônio também diminuiu a expressão do RNAm de IL-6 e TGF-?, enquanto aumentou a expressão de IL-13 no colón dos animais durante a fase de indução da doença, o que provavelmente ajudou na atenuação da inflamação intestinal. Além disso, houve acúmulo de linfócitos CD4+ e CD8+ no baço e diminuição apenas de linfócitos CD4+ nos linfonodos mesentéricos (LNM), indicando retenção das células CD4+ no baço após uso do DHEA. O tratamento foi também capaz de aumentar a frequência de células CD4 produtoras de IL-4 e diminuir CD4+IFN-?+ no baço, além de reduzir a frequência de CD4+IL-17+ nos LNM, sugerindo efeito do DHEA no balanço das respostas Th1/Th2/Th17 relacionadas à colite. Em adição, as células de baço dos animais tratados com DHEA e expostos ao DSS se tornaram hiporresponsivas, como visto pela diminuição da proliferação após re-estímulos in vitro. Finalmente, DHEA foi capaz de atuar no metabolismo dos camundongos tratados, levando à diminuição de colesterol total e da fração LDL no soro durante a fase de indução da doença, sem gerar quaisquer disfunções hepáticas. Com isso, podemos concluir que o DHEA atua por meio do balanço das respostas imunes exacerbadas, minimizando os danos locais e sistêmicos causados pela inflamação intestinal induzida por DSS. / Inflammatory bowel diseases (IBD) are multifactorial diseases whose etiology involves genetic susceptibility, environmental factors, dysbiosis and exacerbated activation of the immune system in the gut. These diseases have also been associated to lower levels of dehydroepiandrosterone (DHEA), a precursor of various steroid hormones, related to modulation of immune responses. However, the precise mechanisms that link the actions of this hormone with protection or susceptibility to Crohn\'s disease or ulcerative colitis are still not fully understood. Thus, this project aimed to understand the immunomodulatory role of exogenous DHEA in vitro and in vivo in experimental intestinal inflammation induced by dextran sodium sulfate (DSS) in C57BL/6 mice. Initially, in vitro, DHEA inhibited the proliferation of spleen cells in a dose dependent way on the concentrations of 5?M, 50?M and 100?M, with decreased production of IFN-?. This hormone was not toxic to myeloid lineage cells, although it caused necrosis of leukocytes at the highest doses (50?M and 100?M), which may have influenced the decrease of the cytokines in vitro. Mice treated with DHEA (40 mg / kg) were evaluated at the induction phase of the disease (day 6) and during tissue repair, when animals exposed to DSS and DHEA for 9 days were maintained in the absence these drugs until the day 15. There was decrease of postmortem score, improved weight and clinical signs of intestinal inflammation, besides reduced peripheral blood monocytes on day 6, together with an increase in circulating neutrophils in tissue repair phase (15 days). Supplementation with DHEA also led to a reduction in cellularity of the lamina propria (LP) and to the restoration of normal length of the gut. The use of this hormone also decreased the expression of of IL-6 and TGF-? mRNA, while IL-13 was augmented in the colon of mice during the induction phase of the disease, a fact probably related to attenuation of intestinal inflammation. Furthermore, there was accumulation of CD4+ and CD8+ cells in the spleen along with decreased CD4+ leukocytes in mesenteric lymph nodes (MLN), indicating retention of CD4+ cells in the spleen after use of DHEA. The treatment was also able to increase the frequency of CD4+ cells producing IL-4 and decrease CD4+IFN-?+ in spleen, with reduced frequency of CD4+IL-17+ in the MLN, suggesting a role for DHEA on the balance of Th1/Th2/Th17 responses related colitis. In addition, splenocytes of mice treated with DHEA and exposed to DSS became hiporresponsives as seen by decreased proliferation after re-stimulation in vitro. Finally, DHEA was able to act on the metabolism of treated mice, leading to decreased total cholesterol and LDL cholesterol in serum during the induction phase of the disease, without generating any liver dysfunction. Thus, we concluded that DHEA acts by balancing the exacerbated immune responses, minimizing local and systemic damages caused by intestinal inflammation induced by DSS.

Objectives: Despite the toll of inflammatory bowel disease (IBD) on adjustment, many patients are resilient to the challenges associated with living with IBD, and successfully cope with their illness and thrive. Yet there is little research on why some individuals with IBD enter a trajectory of growth, while others may struggle to adapt. The aim of this study was to investigate the adjustment‐related factors that distinguished thriving, resilience, and loss in people with IBD across personal growth, life satisfaction, and relationship quality domains. Design: Prospective cohort design with two data collection points, 6 months apart. Methods: From a sample of 420 people with active IBD who completed an online survey, 152 participants completed the follow‐up survey and were included in the analyses. Participants completed measures of thriving, and cognitive, affective, social, and disease‐related variables known to predict adjustment. Results: Time 1 ANCOVAs and pairwise comparisons controlling for demographics distinguished loss from resilience and thriving on the four outcomes – coping efficacy, illness acceptance, depressive symptoms, and perceived social support – for all three domains. Time 2 ANCOVAs and pairwise comparisons controlling for baseline outcomes revealed that the Time thriving categories predicted differences in Time 2 adjustment, mainly for the life satisfaction domain, with those experiencing loss reporting poorer adjustment than those experiencing resilience and thriving. Conclusions: Findings highlight the distinctions among profiles of thriving, resilience, and loss in adjustment to IBD, and suggest that strategies that enhance coping and address depressive symptoms may optimize thriving in the context of IBD.

Background: The 5-hydroxytrptamine receptor 4 (5-HT4 receptor) is heavily expressed on colonic epithelial cells and has been targeted as a therapeutic for functional bowel symptoms and pain; however, adverse cardiac events related to 5-HT4 agonist treatment limited their therapeutic use. Previous studies in the Mawe laboratory have demonstrated that intraluminal application of a 5-HT4 agonist exerts protective epithelial actions in animal models of colitis, and accelerates recovery from colitis. The aim of this study was to test the effects of a luminally restricted 5-HT4 agonist in a mouse model of experimental colitis. Methods: The luminally restricted 5-HT4 agonist (Takeda Pharmaceuticals; 10 mg/kg) was administered to mice during active dextran sodium sulfate (DSS) induced colitis. Colitis activity was evaluated using disease activity index, a fecal lipocalin-2 assay, and histological damage scoring. Epithelial proliferation and colonic motility were also measured as readouts of the potential protective actions and colonic function, respectively. Results: Oral gavage and intracolonic delivery of this luminally restricted 5-HT4 agonist had no detectable effect on recovery from colitis or colonic motility as compared to vehicle. Additionally, in positive control experiments, we failed to see an effect of the 5-HT4 agonist, tegaserod, on colitis severity or colonic motility in any of the measures tested. Conclusions: In conclusion, it is unclear if the luminally restricted 5-HT4 agonist has any effect on recovery from DSS colitis. Given inconsistencies with the model and lack of an effect of tegaserod, additional studies will be required, possibly involving different doses and time points, to fully assess the actions of this luminally restricted compound in colitis recovery.

Abstract Nutritional status affects every aspect of a child?s health. Thorough nutritional assessment is hampered by the lack of a single comprehensive tool, which can cover all aspects of nutritional assessment. In three distinct studies, this thesis investigated the nutritional status of hospitalised children, children with coeliac disease and children with inflammatory bowel disease. Study 1 The objectives of this study were to assess prevalence of malnutrition and nutritional risk, and define demographic and anthropometric factors associated with nutritional risk among hospitalized children. In this cross sectional study, 157 hospitalised children were assessed for nutritional status using nutritional risk score (NRS) and anthropometric measurements. We found that 4.5%, 8.9%, 15.1% and 10.4% children were wasted, stunted, overweight and obese respectively. However, with the NRS, 47.8% of the children were at high nutritional risk. These children at high risk had lower weight for age (p=0.02), lower BMI percentiles for age (p=0.001) and longer hospitalization (p=0.001) than children at no risk. Study 2 The objectives of this study were to determine nutritional parameters in children with coeliac disease. Twenty-five children with coeliac disease and an equal number of age and gender matched controls were enrolled and anthropometric measurements, BIA and leptin levels were analysed in all. No significant differences were found between the children with coeliac disease and controls in these parameters. BMI percentile correlated with leptin levels in children with coeliac disease. Study 3 The objectives of this study were to determine anthropometric parameters and leptin levels in children with IBD and ascertain if BMI correlates with leptin levels in these children. Thirty children with IBD and 60 age and gender matched controls were enrolled. Anthropometric measurements and leptin levels were analysed and compared with controls. IBD children had significantly low weight for age (p=0.002), BMI percentiles (p=0.001) and leptin levels (p=0.009) compared to controls. There was a correlation between BMI and leptin levels in IBD children. In conclusion, this thesis has shown that one quarter of hospitalized children were overweight or obese, and further, that half of the hospitalised children were at high risk of nutritional deterioration and these children had longer hospital stay than children at no risk. Children with coeliac disease had similar anthropometric measurements, body compartments and leptin levels to controls. However, children with IBD had lower anthropometric measurements and leptin levels, indicating under-nutrition. Nutritional assessment should be a mandatory part of clinical management with nutritional status assessed by various tools including NRS, anthropometry, BIA and leptin levels.

Inflammatory bowel disease (IBD) comprises diseases that are characterized by chronic or relapsing inflammation of the gastrointestinal tract. Primary sclerosing cholangitis (PSC) is an extraintestinal manifestation in IBD. Immunoreactivity against an autoantigen that is expressed both in the gastrointestinal tract and the biliary tract could be the link between these diseases. A possible source of such an antigen is goblet cells. Immunostainings of normal human tissues using IBD patient sera showed goblet cell immunoreactivity against goblet cells in all parts of the gastrointestinal tract. The most frequent immunostaining was found against goblet cells in the appendix against which 84% (42/50) of IBD patients compared to 8% (4/50) of healthy blood donors showed immunoreactivity. To identify the corresponding antigen we used three different approaches, investigation of immunoreactivity to different candidate proteins compared to IBD sera, immunoscreening of an appendiceal cDNA library, and immunoprecipitation of protein lysates from mucin producing cells followed by SDS-PAGE and 2D gel electrophoresis. These approaches led to the identification of several candidate autoantigens of which complement C3 is the most promising. A novel staining pattern with strong immunoreactivity to granules and the apical membrane of biliary epithelial cells was identified with 35% (12/34) of PSC sera compared to none of healthy controls (n=28). Screening of a cDNA library from normal human choledochus identified PDZ domain containing 1 (Pdzk1) and Glutathion S transferase theta 1 (GSTT1) as potential candidates. Pdzk1 is an interesting candidate which is expressed in the intestinal tract and bile ducts. GSTT1 antibodies were not specific for PSC and are thought to develop as an alloimmune response in patients with the GSTT1-null genotype. In conclusion, we have identified specific immunoreactivity to goblet cells and biliary epithelial cells using sera from patients with IBD and PSC respectively. We have also identified several potential autoantigens.

Background: There is an unacceptable delay in diagnosis of axial Spondyloarthritis (axSpA) especially in its early stages among patients with inflammatory bowel disease (IBD). Objective: to develop a sensible and reliable questionnaire to identify undetected axSpA among IBD patients. Methods: Candidate items for the questionnaire were selected on 3 domains (IBD, inflammatory back symptoms, and extra-axial features). Sensibility of the Toronto axSpA Questionnaire (TASQ) was assessed leading to drafting 18 items. Test-retest reliability study was conducted among 77 patients with established IBD and axSpA and kappa agreement coefficients were calculated for items. Results: The TASQ was developed using multiple steps of sensibility assessment resulting in 16 items. Kappa coefficients ranged from 0.81 to 1.00 for all items indicating almost perfect agreement. Conclusion: TASQ is a newly developed, sensible and reliable questionnaire that should facilitate identification and referral of IBD patients to rheumatologists and should avoid delay in diagnosis of axSpA.

Endoglin, a co-receptor of the TGF-β superfamily, is predominantly expressed in endothelial cells and in some myeloid cells and implicated as a potential modulator of immune responses. We previously demonstrated that Endoglin heterozygous (Eng+/-) mice subjected to the dextran sulfate sodium colitis model developed persistent inflammation and epithelial ulceration, while Eng+/+ mice recovered following the acute phase of disease. Our aim was to assess potential alterations in distribution and number of immune cells, expression of inflammatory mediators and mechanisms of oxidative burst in Eng+/- mice. While the number of overall T, B and myeloid cells was unaltered between the genotypes, changes in neutrophil regulating cytokines and angiogenesis mediating factors were observed in Eng+/- mice. In addition, downregulation of phagocyte oxidative burst enzymes point to potential defects in microbial clearance in Eng+/- mice. These findings suggest a role for endoglin in regulating immune and vascular functions during inflammation.

Background: There is an unacceptable delay in diagnosis of axial Spondyloarthritis (axSpA) especially in its early stages among patients with inflammatory bowel disease (IBD). Objective: to develop a sensible and reliable questionnaire to identify undetected axSpA among IBD patients. Methods: Candidate items for the questionnaire were selected on 3 domains (IBD, inflammatory back symptoms, and extra-axial features). Sensibility of the Toronto axSpA Questionnaire (TASQ) was assessed leading to drafting 18 items. Test-retest reliability study was conducted among 77 patients with established IBD and axSpA and kappa agreement coefficients were calculated for items. Results: The TASQ was developed using multiple steps of sensibility assessment resulting in 16 items. Kappa coefficients ranged from 0.81 to 1.00 for all items indicating almost perfect agreement. Conclusion: TASQ is a newly developed, sensible and reliable questionnaire that should facilitate identification and referral of IBD patients to rheumatologists and should avoid delay in diagnosis of axSpA.