Irritable bowel syndrome (IBS) is characterized by chronic abdominal pain/discomfort along with altered bowel habits, which accounts for a large proportion of gastrointestinal (GI) disorders worldwide. While psychiatric distress like depression is one of the most frequent comorbidities in IBS patients, which not only influences the quality of life, it also leads to a substantial economic burden and inefficient treatment in IBS patients. Inflammation, altered activities of the HPA axis, aberrant central neuroplasticity and neurotransmission have been highly regarded as pathogenic factors of the depression. Whereas, in recent years, dysfunctions in the gut microbial community has been increasingly discovered to provoke depression disorder. Considering that gut dysbiosis plays causal role in IBS progression, dysfunction of the gut microbiota has been speculated for contributing to the depressive symptoms in IBS (IBS-DP) patients. However, whether and how gut dysbiosis affecting IBS-DP patients remain unclear. We hypothesized that gut microbiota changes contribute to the development of IBS-DP and the change of gut microbiota-driven metabolites induces the structural and/or functional changes of the central nervous system (CNS), thus resulting in the development of IBS-DP. In this thesis, IBS patients with and without depression and animal models of IBS have been systematically studied, to investigate whether gut dysbiosis mediates depressive disorder in IBS. Firstly, we conducted a cross-sectional study involving the distribution of depressive disorder in the IBS population of Hong Kong. According to this survey, we found that there is 36.6% (135/369) of IBS patients showed symptoms of depression. The severity of depressive symptoms was positively associated with the harshness of visceral pain and bloating signatures in IBS patients. Secondly, in comparison to the non-depression of IBS (IBS-ND) group, faecal metagenomic results unveiled the disrupted gut microbiota in IBS-DP patients, mainly with the deficiency of several beneficial bacterial groups, including Akkermansia, Bifidobacterium and Eubacterium, whereas the gut microbiota profile between IBS-ND patients and healthy controls (HCs) showed no significant changes. Compared with HCs, enzyme-linked immunosorbent Assay (ELISA) results showed higher levels of serum IL-1β, IL-6, and TNF-a in IBS-DP patients, indicating a low-grade peripheral inflammation in IBS-DP patients. Moreover, the abundance of Akkermansia muciniphila (A. muciniphila), was negatively correlated with Hamilton Rating Scale for Depression (HAMD) score and Zung Self-Rating Depression Scale (SDS) score, IL-1β, TGF-β, and TNF-a in IBS-DP patients. These findings indicate that gut dysbiosis, especially deficiency in A. muciniphila, is related to the depressive symptoms and inflammation in IBS-DP patients. Thirdly, in a neonatal maternal separation (NMS) rat model, behavioural tests such as colorectal distention (CRD) test, open field test (OFT), forced swimming test (FST), and sucrose preference test (SPT) results showed visceral hypersensitivity and depression symptoms in rats. These results indicate that the model can successfully mimic the visceral hyperalgeisa and the depression-like behaviour of IBS-DP. Immunohistochemical analysis showed an altered morphology and decreased the quantity of astrocytes in the hippocampus of NMS rats when compared with that of controls. More importantly, the mRNA expressions of genes related to Astroglial glutamate transmission including glutamate transporters (GLTs), glutamate receptors, and also glutamate-related exchangers, as well as astrocyte biomarker glial fibrillary acidic protein (GFAP), which are mediated with chronic inflammation and/or stress, were decreased in NMS rats when compared with the control group. These results indicate that impaired astroglial glutamate neurotransmission in NMS rats. Furthermore, pseudo-GF rats with faecal microbiota transplantation (FMT) of NMS microbiota were also conducted, and results showed that the association of A. muciniphila deficiency, depressive-like behaviours and impaired astroglial glutamate neurotransmission were repeated in the rat recipients. These results indicate a causal relationship between NMS microbiota and depressive phenotype, involving dysfunction of the astrocyte- glutamate pathway. Fourthly, to further verify the role of A. muciniphila in NMS microbiota-induced depressive phenotype and impaired astrocytic glutamate pathway, we orally administered live and heat-killed A. muciniphila bacteria in NMS adult rats. A. muciniphila (108 CFU in 1mL PBS) was administered once-daily for four consecutive weeks. Besides, rifaximin and fluoxetine were also separately treated in NMS rats as control groups. Rifaximin is a broad-spectrum GI-specific antibiotic that is commonly used for IBS treatment, and fluoxetine, a selective serotonin re-uptake inhibitor, is one of the most frequently prescribed anti-depressants. The results showed that A. muciniphila efficiently improved depressive-like behaviours, attenuated the impaired astrocytic glutamate neurotransmission, as well as restored the normal morphology and number of astrocytes in the hippocampus of NMS rats. While rifaximin-treated rats only exhibited amelioration of visceral pain, and fluoxetine group mainly performed antidepressant effect, without any significant change in astrocytic glutamate neurotransmission impairment. These results demonstrate that A. muciniphila improves depressive symptoms in IBS phenotype and ameliorate astroglial-glutamatergic pathway dysfunction. Whether and how A. muciniphila modulates astroglial glutamate transmission, therefore leading to the improvement of depressive symptom in IBS, remains to be further investigated. Taken together, the works of this thesis, combining both clinical and animal studies reveal that gut dysbiosis, particularly deficiency of A. muciniphila, contributes to the development of IBS-DP via regulating the astroglial glutamatergic pathway. This study gives a different direction to microbial-guided therapy for the IBS-DP patients in the future

published_or_final_version / abstract / Social Work and Social Administration / Doctoral / Doctor of Philosophy

M.A. (Counselling Psychology) / Please refer to full text to view abstract

Background. Although irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder with an absence of demonstrable pathology, it is associated with significant impairment of quality of life and causes a heavy burden on the health care system. As conventional IBS treatments are far from satisfactory, people turn to Complementary and Alternative Medicine (CAM). One of the most acceptable CAM treatments is acupuncture, which has been considered to be effective in alleviating abdominal bloating, increasing rectal pain threshold, and improving the general well being of IBS patients. However, the underlying mechanisms of these therapeutic effects remain unknown. This study is an investigation of the therapeutic mechanisms of acupuncture treatment of IBS. / Conclusion. Acupuncture attenuates visceral hyperalgesia by inhibiting 5-HT and c-Fos activity in the brain-gut axis. This observation may shed light on possible mechanisms by which acupuncture alleviates symptoms of IBS. / Study 1. A Neonatal Maternal Separation Stress Model (NMSS) was tested. Our results showed that this model was a reliable and stable model for IBS animal study and that visceral hyperalgesia was associated with increased serotonin (5-HT) and c-Fos activity of the brain-gut axis. / Study 2. Two methods were used to test visceral hyperalgesia in response to colorectal distension (CRD), namely Abdominal Withdrawal Response (AWR) and Electromyogram (EMG). There methods were compared for their effectiveness in measuring visceromotor response (VMR) in a NMSS rat model. Our results showed that EMG is the more reliable tool for evaluating VMR to CRD in NMSS rats. / Study 3. There were three parts to this study. First, we reviewed the TCM literature on the use of acupuncture in IBS and concluded that the two most commonly used acupoints for this condition are ST-36 and CV-12 and that, of the two, ST-36 may be the more appropriate acupoint for treatment. Second, we tested invasive and non-invasive sham acupuncture (placebo) and found that neither produces any therapeutic effect when compared to real electroacupuncture. Third, we used the NMSS rat as the animal model, ST-36 as the treatment acupoint, non-invasive sham acupuncture as the placebo, and EMG as the tool to evaluate VMR in response to CRD alter acupuncture intervention. Our results showed that acupuncture not only attenuated 5-HT and c-Fos activity but also reduced visceral hyperalgesia in the NMSS rat. / Ziea, Tat Chi. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3423. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 122-141). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

M.A. / Irritable bowl syndrome (IBS) is one of the common conditions referred to gastroentorologists, but one of the least understood. Part of the reason for this is the real lack of consensus of opinion regarding the nature of the complaint. The problem is confounded by the absence of objective disease makers, as well as the variation in symptom presentation. The term (IBS) describes a cluster of symptoms which include chronic abdominal pain and altered bowel habits (diarrhoea, constipation, or alternating diarrhoea and constipation) in the absence of a known structural cause for the symptom (Toner, Garfinkel, Jeejeebhoy, Scher, Shulhan & Di Gasbarro, 1990). The symptoms of IBS mimic those of many other gastrointestinal diseases and the challenge to medical doctors is to establish a confident diagnosis based on the symptomatology of the individual, without the need to carry out multiple investigations to eliminate organic disease of the bowel. The pathogenesis of a condition remains a mystery. Most doctors would not consider IBS to a 'proper" disease at all, but view it as a physiological alteration in intestinal function brought about by psychological disturbance (Read, 1985).

M.A. / Irritable bowel syndrome has the dubious honour of being one of the most widely researched, yet poorly understood gastrointestinal disorders. Vast amounts of research have been conducted into every facet of this disorder, yet the investigations yield results that are often contradictory and more conducive to complication than clarification. In light of the quote above, it becomes apparent that research into IBS has fulfilled the requirements for 'serious research', leaving medical practitioners and researchers with more questions than answers. Irritable bowel syndrome is a bowel disorder characterised by abdominal pain and either diarrhoea or constipation (Bennett, 1989). It is estimated to affect 8 to 15% of the population, and accounts for between 50% and 70% of referrals to gastroenterology clinics (Whitehead & Schuster, 1985). Such a common disorder should be well understood but it is not. In fact, there is little consensus amongst clinicians and researchers concerning the underlying cause of this syndrome. Organic causes which have been suggested include abnormal motor activity of the intestinal tract (Snape et al., 1976), abnormal gut hormone secretion and sensitivity (Ritchie, 1973, in Lynn & Friedman, 1993) and diet (Jones et al., 1982, in Corney et al., 1991). Many studies have also indicated that psychological factors are important and that patients with this syndrome are more neurotic, depressed or anxious than others (Hislop, 1971; Young et al., 1976). Research findings have tended to be contradictory, yet one common thread throughout the literature has been the role that stress seems to play in both the onset and maintenance of IBS. A number of studies have been conducted in this area, yet once again the findings have been contradictory and little clarity has been achieved. It is against this background that the aims of the present study can be described. The aims of the present study are twofold. The first, and most specific aim is to clarify the relationship between psychological stress and IBS. In particular, the present investigation will explore the differences in daily and occupational stress between healthy individuals and those suffering from IBS. The second aim of this research more general, and concerns theory building. This is particularly important in a field where there has been so much ambiguity and confusion.

Advances in DNA sequencing of microbial communities have revealed a complex relationship between the human microbiome and our health. Community dynamics, host-microbe interactions, and changing environmental pressures create a dynamic ecosystem that is just beginning to be understood. In this work, we develop methods for investigating the dynamics of the microbiome. First, we develop a model for describing community dynamics. We show that the proposed approaches accurately describes community trajectories over time. Next, we develop a method for modeling and eliminating technical noise from longitudinal data. We demonstrate that the method can accurately reconstruct microbial trajectories from noisy data. Finally, we develop a method for estimating bacterial growth rates from metagenomic sequencing. Using a case-control cohort of individuals with irritable bowel disease, we show how growth rates can be associated with disease status, community states, and metabolites. Altogether, these models can be used to help uncover the relationship between microbial dynamics, human health, and disease.

M.A. / The overall objective of the global research project of which the present study is a part, is to create a greater awareness and understanding of the association between physiology and psychology, specifically with regard to IBS. Investigations are being conducted into the contribution of such factors as stress, anxiety, depression, somatization, psychopathology. early sexual abuse and physical abuse to the development and management of IBS. The present study aims to assess the incidence of co-morbid psychopathology in patients with IBS as compared to the general population. 1.3.2 Specific Aims. The aim of the present study is to compare the incidence of concurrent psychopathology in a sample of white, female patients, aged from 25-55 years and diagnosed to have IBS, with the incidence of psychopathology in a sample of white female non-IBS controls aged 25-55 years. Of initial concern will be whether the results of this study confirm the findings of the numerous research projects which attest to the high incidence of comorbid psychopathology in patients with IBS (Chaudhary & Truelove, 1962; Liss et al., 1973; Young et al., 1976), or add support to the limited evidence that disputes these claims (Talley, Kramlinger et al., 1993; Thornton, McIntyre et al., 1990). The study then aims to consider whether the variable of gender has a significant effect on the incidence of co-morbid psychopathology in patients with IBS. As will be discussed in Chapter 3, most of the studies do not differentiate between male and female subjects even though this may well prove to be an important determining factor. As mentioned in section 1.2.1, there is a dearth of research in South Africa into IBS and, more specifically, into the incidence of co-morbid psychopathology and IBS. By restricting participants in this study to those of the white race, the aim of this study is to initiate a process in which the incidence of co-morbid psychopathology in IBS patients of all races will be assessed and compared. In addition, the present study aims to assess whether age and level of education are significant variables in determining the incidence of co-morbid psychopathology in patients with IBS. Inter-group comparisons will be made between three groups of patients with IBS divided first according to age and then according to level of education. Finally, the present study aims to be more methodologically sound than certain of the earlier research projects as reported in the literature. As will become clear in Chapters 2 and 3, a common thread running through much of the literature is the concern that the validity of results may be questionable due to methodological flaws in the design of certain research projects. Small sample size has been a problem in some studies (Liss et al., 1973; Young et al., 1976) whilst in others, the absence of a control group has limited the relevance of data (Liss et al., 1973). Furthermore, a diversity of measuring instruments have been used in the past with little if any standardisation or control of specific variables being assessed. The measuring instrument used in this study, namely the Personality Assessment Inventory (PAI), allows for an accuracy and comprehensiveness of assessment not found in many previous studies (see Chapter 6, section 6.2.1.4). The PAI assesses psychopathological trends in personality functioning. The word "psychopathology" will be used in this study as substitute for the phrase "psychopathological trends in personality functioning".

Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Background: Irritable bowel syndrome (IBS) is a common gastrointestinal (GI) disorder. GI symptoms and impaired quality of life affect between 10-20% of all adults, corresponding to about 25-50% of all patients who visit a gastroenterologist’s clinic. In recent years, several novel mechanisms of IBS that likely relate to previously established theories have been identified. Inflammation, postinfectious low-grade inflammation, immunological and genetic predisposition along with altered microbiota are critical in IBS development, while several dietary factors may also play a role in this syndrome. However, none of these factors accounts for the full repertoire of IBS symptoms, and the pathophysiology of this condition is not fully understood. The overarching aim of this study was to investigate the nutrient intakes, GI microbiota and the effect of Lactobacillus plantarum (L.plantarum) 299v in IBS patients. Sub-aims: 1) Update healthcare professionals on current probiotic information and provide an overview of probiotic treatment approaches, with special emphasis on IBS, 2) conduct a well designed randomised, double blind, placebo-controlled trial (RCT) with L. plantarum 299v as part of an intervention and establish whether a course of probiotics may alleviate undesirable symptoms of IBS and improve quality of life, 3) assess nutrient intake in patients with irritable bowel syndrome (IBS) compared to dietary recommendations, 4) validate and assess the reproducibility of food records and 5) identify possible nutrient risk components for establishing GI microbiota involved in IBS and as part of an intervention, determine whether a course of probiotics may alter stool microbiota. Results: 1) A review article published by the author provides an overview of current probiotic treatment options to health care professionals and indicates certain probiotics are a promising therapeutic treatment option for management of IBS symtpoms, 2) the effects of the single strain probiotic, L. plantarum 299v, supplementation was evaluated in a RCT. Compared to placebo, the probiotic supplementation showed no significant reduction in GI symptom severity scores, particularly abdominal pain relief. Quality of life was also not improved in the treatment versus control group. Both the treatment and placebo groups improved significantly over the trial period, indicating a large placebo effect, 3) nutrient intakes of the IBS patients compared to current dietary reference recommendations indicates that this group of patients are at risk for nutrient inadequacies in key macro and micronutrients, 4) the validity and reliability of the dietary data showed good reliability but poor validity as measured by plasma fatty acids and 5) the GI microbiota composition in the phenotypically different diarrhoea-predominant IBS (D-IBS) vs. constipation-predominant IBS (C-IBS) showed that D-IBS patients had significantly lower counts of Lactobacillus plantarum compared to C-IBS patients. The probiotic had no significant effects on the GI microbiota as measured by quantitative polymerase chain reaction (qPCR). It was found that nutrient intakes had a significant impact on the microbiota. Lower fibre intakes were associated with higher Bacteroides spp., lower Bifidobacteria bifidum and Lactobacillus plantarum counts in both IBS groups. Conclusion: Taken together, L.plantarum 299v did not alleviate the GI symptoms of IBS, nor was it associated with significant changes in the GI microbiota. IBS patients may be at risk of key nutrient inadequacies. The influence of nutrient intakes on the GI microbiota provides an attractive explanation as a potential pathophysiological factor for IBS. / AFRIKAANSE OPSOMMING: Agtergrond: Prikkelbare derm-sindroom (PDS) is ‘n algemene gastro-intestinale (GI) stoornis. GI simptome affekteer die lewenskwaliteit van 10-20% van alle volwassenes. Dit stem ooreen met ongeveer 25-50% van alle pasiënte wat ‘n gastroënteroloog konsulteer. Verskeie oorspronklike meganismes vir die ontwikkeling van PDS is onlangs identifiseer. Inflammasie, post-infektiewe lae-graadse inflammasie, immunologiese en genetiese vatbaarheid tesame met veranderde mikrobiota is krities vir die ontwikkeling van PDS. Sekere dieetfaktore mag ook bydraend wees tot hierdie sindroom. Geen van hierdie faktore is egter verantwoordelik vir die volle spektrum van PDS simptome nie en die patofisiologie van die toestand word ook nog nie ten volle verstaan nie. Die oorkoepelende doel van hierdie studie is om nutriëntinname, GI mikrobiota en die uitwerking van L.plantarum 299v in PDS pasiënte bepaal. Sub-doelwitte: 1) Om gesondheidswerkers in te lig aangaande die nuutste inligting oor probiotika en om ‘n oorsig van probiotika behandelingsopsies te verskaf, met spesiale klem op PDS, 2) om ‘n goed beplande ewekansige, dubbel-blinde, plasebo-beheerde kliniese studie met L.plantarum 299v as deel van die intervensie uit te voer om sodoende te bepaal of ‘n kursus probiotika ongewensde simptome van PDS kan verbeter en lewenskwaliteit sodoende verhoog, 3) om nutriëntinname in pasiënte met PDS te bepaal vergeleke met dieet aanbevelings, 4) om die geldigheid en herhaalbaarheid van voedselrekords te bepaal en 5) om moontlike nutriënt risikokomponente vir die ontwikkeling van GI mikrobiota betrokke in PDS te identifiseer en om as deel van ‘n intervensie te bepaal of ‘n kursus probiotika stoelgang mikrobiota patrone verander. Resultate: 1) ‘n Oorsigartikel gepubliseer deur die kandidaat dui probiotika aan as ‘n belowende terapeutiese opsie in die behandeling van PDS simptome, 2) die effek van ‘n enkelstam probiotikum, L.plantarum 299v, is evalueer deur ‘n ewekansige, dubbel-blinde, plasebo-beheerde kliniese studie. Vergeleke met die plasebo, het probiotiese aanvulling geen betekenisvolle vermindering in die GI simptome in PDS pasiënte tot gevolg gehad nie. Lewenskwaliteit het ook nie verbeter in die behandelde versus die kontrole groep nie. Beide die behandelde en plasebo groepe het aansienlik verbeter oor die studietydperk, wat ‘n groot plasebo effek aandui, 3) nutriëntinname van die PDS groep vergeleke met huidige dieetaanbevelings, dui daarop dat hierdie groep pasiënte ‘n risiko het vir die ontwikkeling van kern nutriënttekorte (makro- en mikronutriënte), 4) die geldigheid en betroubaarheid van die dieetdata dui op goeie betroubaarheid, maar swak geldigheid soos bepaal deur plasma vetsure en 5) die dermkanaal mikrobiotiese samestelling in die verskillende fenotipes, diarree-oorheersende PDS (D-PDS) vs. konstipasie-oorheersende PDS (K-PDS) dui daarop dat D-PDS pasiënte aansienlike minder Lactobacillus plantarum gehad het vergeleke met K-PDS pasiënte. Die probiotikum het geen beduidende uitwerking op die oorheersende mikrobiota gehad nie, soos gemeet deur kwantitatiewe polimerase kettingreaksie (kPKR). Daar is gevind dat dieet ‘n beduidende impak op die mikrobiota gehad het. Daar is ‘n verband tussen laer vesel inname en hoёr Bacteroides spp. en laer Bifidobacteria bididum en Lactobacillus plantarum tellings gevind in beide PDS groepe. Gevolgtrekking: Die L.plantarum 299v enkelstam probiotikum het nie die gastrointestinale simptome van PDS pasiënte verlig nie en daar is ook geen beduidende veranderinge in die mikrobiota gevind nie. PDS pasiënte mag ‘n verhoogde risiko toon vir kern nutriënttekorte. Die invloed van nutriëntinname op GI mikrobiota verskaf ‘n belowende verduideliking as ‘n potensiële patofisiologiese faktor in PDS.

El síndrome del intestino irritable es un trastorno común que afecta a millones de personas en todo el mundo. Dicho transtorno tiene un impacto significativo en la calidad de vida de las personas que lo padecen afectando en mayor o menor medida la esfera sociolaboral de estos individuos con el consecuente sufrimiento individual e impacto macroeconómico por aumento en las tasas de ausentismo y rendimiento laboral. Los prebióticos y probióticos son suplementos de la dieta no digerible, elementos químicos y microorganismos vivos (bacterias o levaduras de la flora comensal intestinal) que al consumirlos en volúmenes óptimos (tratamiento simbiótico), resultan beneficiosos para la salud humana. La mucosa intestinal es sin duda la mayor superficie del organismo humano expuesta al medio externo, ademas de contener una alta densidad de células inmunitarias. La alteración de la homeostasis entre los microorganismos beneficiosos y potencialmente nocivos de la microflora intestinal se expresa en un incremento del riesgo a padecer infecciones y enfermedades inmunoinflamatorias y, en este sentido, los pre y probióticos ayudan a mantener esta armonía. / Irritable intestine syndrome is a common condition that affects millions of persons all over the world. It has a significant impact in the quality of life of affected persons, influencing their social and working environments and leading to individual suffering and a macroeconomic impact because of increased absenteeism and poor working performance. Prebiotics and probiotics are supplements of nondigestible diet, made up of some chemicals and live microorganisms (bacteria or yeasts from the intestinal commensal flora), which, when ingested in optimal amounts (symbiotic therapy), are beneficial for human health. With no doubt, the intestinal mucosa is the greatest surface in the human body exposed to external stimuli, and it also contains a high proportion of immune cells. Any alteration in homeostasis between beneficial and potentially harmful microorganisms in the intestinal microflora is expressed as an increased risk for the occurrence of infectious and immune and inflammatory diseases; therefore, prebiotics and probiotics may help to maintain a harmonic environment in the intestine. / Revisión por pares