Myeloid-derived suppressor cells (MDSCs), characterized by the co-expression of CD11b and Gr1, are a heterogeneous population of immature myeloid cells that exhibit strong suppressive functions against T cell responses. In inflammatory conditions like IBD, there is an increase in MDSCs but this is not sufficient to improve intestinal inflammation in IBD. Herein, we investigated the expansion of MDSCs in TNBS-induced acute colitis and whether the adoptive transfer of in vitro generated MDSCs ameliorated intestinal inflammation. We found that CD11b+Gr1+ MDSCs were significantly increased in experimental colitis. Further, this increase correlated to some extent with the severity of the disease. As per our protocol, MDSCs were generated from bone marrow cells co-cultured with hepatic stellate cells (HSCs), an essential cell type to obtain functional MDSCs in vitro. Adoptive transfer of HSC-induced MDSCs improved body weight loss and significantly downregulated inflammatory cytokines TNF, IFN-γ, and IL-17 in colonic tissue. Our results indicate MDSCs are immunoregulatory players in intestinal inflammation and that the adoptive transfer of in vitro generated MDSCs may provide a novel therapeutic approach for inflammatory bowel disease.

Glucagon-like peptide-2 (GLP-2) augments intestinal adaptation in animal models of short bowel syndrome (SBS) and in adult patients with SBS. However, GLP-2 has not been used as a therapy for pediatric SBS. In this thesis, it is hypothesized that exogenous GLP-2 therapy will improve outcomes of intestinal adaptation in proximal intestinal resection (JI) and distal intestinal resection (JC) neonatal piglet models of SBS. Improvements in morphological parameters (increased small intestinal length) and histological parameters (increased jejunal villus length or jejunal crypt depth) of intestinal adaptation in JI and JC neonatal piglets treated with GLP-2 were observed. However, improved clinical outcomes (fewer days of diarrhea, fewer days on parenteral nutrition, more days on enteral nutrition alone) were only observed in GLP-2 treated JC animals. Since the JC anatomical subtype (no remnant ileum) represents the majority of clinical cases of neonatal SBS, these results support a potential role for GLP-2 therapy in pediatric SBS.

Polymorphisms in organic cation transporters SLC22A4, SLC22A23 and IBD5 locus have been associated with pathogenesis of inflammatory bowel disease (IBD). We sought to investigate the association of polymorphisms in these genes to IBD risk in a Canadian population, subclone and express human SLC22A23 gene to determine the localization in the cell. DNA samples from 160 patients with Crohn´s disease (CD), 149 patients with ulcerative colitis (UC) and 142 healthy controls were genotyped by PCR-RFLP analysis or TaqMan system. Gateway® recombination technology was used to transform and express SLC22A23 gene in HEK 293 cell line. Polymorphisms in the IBD5 locus rs17622208-AA genotype and rs11739135-CC genotype increase the risk of CD. Moreover, carriers of SLC22A23 polymorphisms rs4959235-TT genotype and rs9503518-GG genotype increase dramatically the risk of UC. We confirm that SLC22A23 polymorphisms are important in the pathogenesis of IBD and they can ultimately be used as biomarkers of the disease risk.

Myeloid-derived suppressor cells (MDSCs), characterized by the co-expression of CD11b and Gr1, are a heterogeneous population of immature myeloid cells that exhibit strong suppressive functions against T cell responses. In inflammatory conditions like IBD, there is an increase in MDSCs but this is not sufficient to improve intestinal inflammation in IBD. Herein, we investigated the expansion of MDSCs in TNBS-induced acute colitis and whether the adoptive transfer of in vitro generated MDSCs ameliorated intestinal inflammation. We found that CD11b+Gr1+ MDSCs were significantly increased in experimental colitis. Further, this increase correlated to some extent with the severity of the disease. As per our protocol, MDSCs were generated from bone marrow cells co-cultured with hepatic stellate cells (HSCs), an essential cell type to obtain functional MDSCs in vitro. Adoptive transfer of HSC-induced MDSCs improved body weight loss and significantly downregulated inflammatory cytokines TNF, IFN-γ, and IL-17 in colonic tissue. Our results indicate MDSCs are immunoregulatory players in intestinal inflammation and that the adoptive transfer of in vitro generated MDSCs may provide a novel therapeutic approach for inflammatory bowel disease.

The sympathetic nervous system (SNS) is part of an integrative network that functions to restore homeostasis following injury and infection. The SNS provides negative feedback control over inflammation through the secretion of catecholamines from postganglionic sympathetic neurons and adrenal chromaffin cells (ACCs). Central autonomic structures receive information regarding the inflammatory status of the body and reflexively modulate SNS activity. Evidence suggests that inflammation and infection can also directly regulate ACC function. However, the precise alterations in ACC function that occur in response to regional inflammation, systemic inflammation and exposure to bacterial products have yet to be fully characterized. The present thesis was therefore performed to test the hypothesis that gastrointestinal (GI) and systemic inflammation modulate ACC Ca2+ signaling, and that ACCs possess the ability to directly detect microbe-associated molecular patterns (MAMPs). Ca2+ signaling was assessed in single ACCs isolated from control mice and mice with GI or systemic inflammation using Ca2+ imaging and perforated patch clamp electrophysiology. Acute and chronic GI inflammation consistently reduced high-K+-stimulated Ca2+ transients in ACCs through an inhibition of voltage-gated Ca2+ current. In contrast, systemic inflammation significantly enhanced high-K+-stimulated Ca2+ transients and catecholamine secretion through an increase in Ca2+ release from the endoplasmic reticulum. Incubation of control ACCs in serum obtained from mice with systemic inflammation produced a similar increase in Ca2+ signaling, suggesting that circulating mediators play an important role in this response. To determine whether ACCs can directly detect MAMPs, Ca2+ signaling, excitability and neurotransmitter release were assessed in control ACCs and ACCs incubated in media containing lipopolysaccharide (LPS). Unlike GI and systemic inflammation, LPS did not affect ACC Ca2+ signaling. However, LPS dose- and time-dependently hyperpolarized ACC resting membrane potential and enhanced large conductance Ca2+-activated K+ currents. Consistent with membrane hyperpolarization, LPS reduced ACC excitability and inhibited neuropeptide Y release. These effects were mediated by Toll-like receptor 4 and nuclear factor-κB. In summary, GI and systemic inflammation produce opposite effects on ACC Ca2+ signaling through distinct mechanisms, and ACCs can directly detect MAMPs. These findings extend our knowledge of the complex integration performed by the immune system-nervous system network during health and disease. / Thesis (Ph.D, Physiology) -- Queen's University, 2013-08-20 17:15:23.945

Background: Inflammatory bowel disease (IBD) is an umbrella term for ulcerative colitis and Crohn's disease. These are characterized by a chronic inflammation of the intestinal mucosa. Living with chronic illness meant that life changed significantly. Quality of life was affected for these individuals and was stressful in their lives.   Aim: The aim was to describe the experiences of living with inflammatory bowel disease.   Method: A qualitative literature review was chosen to analyze articles that were related to the aim of this study.   Results: Based on the chosen articles five themes were created; Commuting between hope and fear, symptoms of the disease and medication become everyday focus, struggling with  the new identity, desire to control the disease- do I control my illness or does it control me and social relationships are affected.   Conclusion: Inflammatory bowel disease is a distressing disease and can cause limitations in social life due to lack of knowledge by others about the disease. The affected felt a loss of control in their life due to the difficulty in managing the symptoms. They experienced a constant struggle and mixed emotions, such as anxiety, depression, stress, and denial of the disease, trying to feel like a healthy person.

An imbalance of the T cell immune response is observed in inflammatory bowel disease. Intestinal microbes have been linked to the disease and the disease process leads to severe mucosal injury and systemic translocation of bacterial products. Aminosalicylates, corticosteroids and immunomodulators reduce these aggressive activities but are associated with potentially serious adverse events. The aim of this work was to investigate the effects of administration of prebiotics and probiotics that modulate the gut microflora and modulate the immune response, in ameliorating severity of colitis. The prebiotic, high amylose maize resistant starch was used at two different concentrations. A number of Bifidobacterium and Lactobacillus strains were used as probiotics. BALB/c mice were administered the prebiotics and probiotics and intrarectally infused with 2.5 mg trinitrobenzene sulfonic acid (TNBS) in 45% ethanol, thereby generating colitis. Mucosal cytokine responses, colonic microbial profiles and disease activity indices were monitored. The 5% concentration of high amylose maize resistant starch delayed progression of TNBS colitis as evidenced by reduced weight loss, lesser tissue damage, abrogation of the expression and synthesis of IFN-?? and upregulation of IL-4 and IL-10. The 30% concentration of high amylose maize resistant starch exacerbated the inflammatory response with an increase in acetic acid, coliforms and endopores in the colonic contents. Three strains of bifidobacteria and 3 strains of lactobacilli were individually screened for their activity against TNBS colitis. Each strain had a distinctive effect on the course of colon inflammation. Lactobacillus fermentum VRI 003 was selected for further study as it provided most protection. The ratio of immunosuppressive cytokines to pro-inflammatory cytokines was restored closer to the normal T cell cytokine levels. It also reduced the incidence of translocation of enteric bacteria into the spleens. Dosing a minimum daily dose of 6x109 CFU L. fermentum VRI-003 to ulcerative colitis patients in remission and maintained on standard therapy for 6 months prevented the exacerbation of symptoms, including diarrhea and abdominal pain, and improved the patient general well being. It also suppressed production of IFN-?? and sustained IL-10 levels. Moreover, absence of endospores and lower numbers of coliforms were detected in the faeces of UC patients during L. fermentum VRI-003 treatment. In summary, 5% high amylose maize resistant starch and L. fermentum VRI 003 prevented colon inflammation by changing the nature of the T cell immune response and modifying the colonic microflora in the murine model. The clinical evidence supported these findings.

Thesis (Ph. D. in Cell and Developmental Biology)--Vanderbilt University, May 2008. / Title from title screen. Includes bibliographical references.

Thesis (M.Sc.)--University of Alberta, 2009. / A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Medicine. Title from pdf file main screen (viewed on September 18, 2009). Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 116-130).