Showing papers by "Fergus Shanahan published in 2013"

The microbiome-gut-brain axis during early life regulates the hippocampal serotonergic system in a sex-dependent manner

Abstract: Bacterial colonisation of the intestine has a major role in the post-natal development and maturation of the immune and endocrine systems. These processes are key factors underpinning central nervous system (CNS) signalling. Regulation of the microbiome-gut-brain axis is essential for maintaining homeostasis, including that of the CNS. However, there is a paucity of data pertaining to the influence of microbiome on the serotonergic system. Germ-free (GF) animals represent an effective preclinical tool to investigate such phenomena. Here we show that male GF animals have a significant elevation in the hippocampal concentration of 5-hydroxytryptamine and 5-hydroxyindoleacetic acid, its main metabolite, compared with conventionally colonised control animals. Moreover, this alteration is sex specific in contrast with the immunological and neuroendocrine effects which are evident in both sexes. Concentrations of tryptophan, the precursor of serotonin, are increased in the plasma of male GF animals, suggesting a humoral route through which the microbiota can influence CNS serotonergic neurotransmission. Interestingly, colonisation of the GF animals post weaning is insufficient to reverse the CNS neurochemical consequences in adulthood of an absent microbiota in early life despite the peripheral availability of tryptophan being restored to baseline values. In addition, reduced anxiety in GF animals is also normalised following restoration of the intestinal microbiota. These results demonstrate that CNS neurotransmission can be profoundly disturbed by the absence of a normal gut microbiota and that this aberrant neurochemical, but not behavioural, profile is resistant to restoration of a normal gut flora in later life.

Bifidobacterium infantis 35624 modulates host inflammatory processes beyond the gut

Abstract: Certain therapeutic microbes, including Bifidobacteria infantis (B. infantis) 35624 exert beneficial immunoregulatory effects by mimicking commensal-immune interactions; however, the value of these effects in patients with non-gastrointestinal inflammatory conditions remains unclear. In this study, we assessed the impact of oral administration of B. infantis 35624, for 6‒8 weeks on inflammatory biomarker and plasma cytokine levels in patients with ulcerative colitis (UC) (n = 22), chronic fatigue syndrome (CFS) (n = 48) and psoriasis (n = 26) in three separate randomized, double-blind, placebo-controlled interventions. Additionally, the effect of B. infantis 35624 on immunological biomarkers in healthy subjects (n = 22) was assessed. At baseline, both gastrointestinal (UC) and non-gastrointestinal (CFS and psoriasis) patients had significantly increased plasma levels of C-reactive protein (CRP) and the pro-inflammatory cytokines tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) compared with health...

Phylogenetic Analysis of Dysbiosis in Ulcerative Colitis During Remission

Abstract: BACKGROUND:: Presence of intestinal microbes is a prerequisite for the development of ulcerative colitis (UC), although deviation of the normal intestinal microbiota composition, dysbiosis, is presumably implicated in the etiology of UC. METHODS:: The fecal microbiota of 30 UC samples obtained from 15 patients who were sampled twice and from 15 healthy control subjects originating from 2 geographic locations was analyzed using highly reproducible phylogenetic microarray that has the capacity for detection and quantification of more than 1000 intestinal bacteria in a wide dynamic range. RESULTS:: The fecal microbiota composition is not significantly influenced by geographic location, age, or gender, but it differs significantly between the patients with UC and the control subjects (P = 0.0004). UC-associated microbiota is stable during remission and similar among all patients with UC. Significant reduction of bacterial diversity of members of the Clostridium cluster IV and significant reduction in the abundance of bacteria involved in butyrate and propionate metabolism, including Ruminococcus bromii et rel. Eubacterium rectale et rel., Roseburia sp., and Akkermansia sp. are markers of dysbiosis in UC. Increased abundance of (opportunistic) pathogens including Fusobacterium sp., Peptostreptococcus sp., Helicobacter sp., and Campylobacter sp. as well as Clostridium difficile were found to be associated with UC. CONCLUSIONS:: Dysbiosis in UC is stable in time and shared between patients from different geographic locations. The microbial alterations offer a mechanistic insight into the pathogenesis of the disease

Divergent metabolic outcomes arising from targeted manipulation of the gut microbiota in diet-induced obesity

Abstract: Objective The gut microbiota is an environmental regulator of fat storage and adiposity. Whether the microbiota represents a realistic therapeutic target for improving metabolic health is unclear. This study explored two antimicrobial strategies for their impact on metabolic abnormalities in murine diet-induced obesity: oral vancomycin and a bacteriocin-producing probiotic ( Lactobacillus salivarius UCC118 Bac + ). Design Male (7-week-old) C57BL/J6 mice (9–10/group) were fed a low-fat (lean) or a high-fat diet for 20 weeks with/without vancomycin by gavage at 2 mg/day, or with L salivarius UCC118Bac + or the bacteriocin-negative derivative L salivarius UCC118Bac − (each at a dose of 1×10 9 cfu/day by gavage). Compositional analysis of the microbiota was by 16S rDNA amplicon pyrosequencing. Results Analysis of the gut microbiota showed that vancomycin treatment led to significant reductions in the proportions of Firmicutes and Bacteroidetes and a dramatic increase in Proteobacteria , with no change in Actinobacteria. Vancomycin-treated high-fat-fed mice gained less weight over the intervention period despite similar caloric intake, and had lower fasting blood glucose, plasma TNFα and triglyceride levels compared with diet-induced obese controls. The bacteriocin-producing probiotic had no significant impact on the proportions of Firmicutes but resulted in a relative increase in Bacteroidetes and Proteobacteria and a decrease in Actinobacteria compared with the non-bacteriocin-producing control. No improvement in metabolic profiles was observed in probiotic-fed diet-induced obese mice. Conclusion Both vancomycin and the bacteriocin-producing probiotic altered the gut microbiota in diet-induced obese mice, but in distinct ways. Only vancomycin treatment resulted in an improvement in the metabolic abnormalities associated with obesity thereby establishing that while the gut microbiota is a realistic therapeutic target, the specificity of the antimicrobial agent employed is critical.

Movers and shakers: influence of bacteriophages in shaping the mammalian gut microbiota.

Abstract: The human intestinal microbiota is one of the most densely populated ecosystems on Earth, containing up to 1013 bacteria/g and in some respects can be considered an organ itself given its role in human health. Bacteriophages (phages) are the most abundant replicating entities on the planet and thrive wherever their bacterial hosts exist. They undoubtedly influence the dominant microbial populations in many ecosystems including the human intestine. Within this setting, lysogeny appears to be the preferred life cycle, presumably due to nutrient limitations and lack of suitable hosts protected in biofilms, hence the predator/prey dynamic observed in many ecosystems is absent. On the other hand, free virulent phages in the gut are more common among sufferers of intestinal diseases and have been shown to increase with antibiotic usage. Many of these phages evolve from prophages of intestinal bacteria and emerge under conditions where their bacterial hosts encounter stress suggesting that prophages can significantly alter the microbial community composition. Based on these observations, we propose the “community shuffling” model which hypothesizes that prophage induction contributes to intestinal dysbiosis by altering the ratio of symbionts to pathobionts, enabling pathobiont niche reoccupation. The consequences of the increased phage load on the mammalian immune system are also addressed. While this is an area of intestinal biology which has received little attention, this review assembles evidence from the literature which supports the role of phages as one of the biological drivers behind the composition of the gut microbiota.

Targeting the Microbiota to Address Diet-Induced Obesity: A Time Dependent Challenge

Abstract: Links between the gut microbiota and host metabolism have provided new perspectives on obesity. We previously showed that the link between the microbiota and fat deposition is age- and time-dependent subject to microbial adaptation to diet over time. We also demonstrated reduced weight gain in diet-induced obese (DIO) mice through manipulation of the gut microbiota with vancomycin or with the bacteriocin-producing probiotic Lactobacillus salivarius UCC118 (Bac+), with metabolic improvement achieved in DIO mice in receipt of vancomycin. However, two phases of weight gain were observed with effects most marked early in the intervention phase. Here, we compare the gut microbial populations at the early relative to the late stages of intervention using a high throughput sequencing-based analysis to understand the temporal relationship between the gut microbiota and obesity. This reveals several differences in microbiota composition over the intervening period. Vancomycin dramatically altered the gut microbiota composition, relative to controls, at the early stages of intervention after which time some recovery was evident. It was also revealed that Bac+ treatment initially resulted in the presence of significantly higher proportions of Peptococcaceae and significantly lower proportions of Rikenellaceae and Porphyromonadaceae relative to the gut microbiota of L. salivarius UCC118 bacteriocin negative (Bac-) administered controls. These differences were no longer evident at the later time. The results highlight the resilience of the gut microbiota and suggest that interventions may need to be monitored and continually adjusted to ensure sustained modification of the gut microbiota.

A randomized controlled study of mesalamine after acute diverticulitis: Results of the DIVA trial

Abstract: Background/Aims:We evaluated the efficacy of mesalamine (Asacol) in reducing gastrointestinal symptoms after an acute attack of diverticulitis.Methods:This was a 1-year double-blind, randomized, placebo-controlled study in which patients with computed tomography scan confirmed acute diverticulitis r

Identification of TLR10 as a Key Mediator of the Inflammatory Response to Listeria monocytogenes in Intestinal Epithelial Cells and Macrophages

Abstract: Listeria monocytogenes is a Gram-positive bacterium that can cause septicemia and meningitis. TLRs are central receptors of the innate immune system that drive inflammatory responses to invading microbes such as L. monocytogenes. Although intestinal epithelial cells (IECs) represent the initial point of entry used by L. monocytogenes for infection, the innate immune response to L. monocytogenes in these cells has been poorly characterized to date. The aim of this study was to determine which TLRs are involved in mediating the immune response to L. monocytogenes in IECs. We performed an RNA interference screen of TLRs 1-10 in the HT-29 IEC cell line and observed the most significant reduction in chemokine output following silencing of TLR10. This effect was also observed in the macrophage cell line THP-1. The chemokines CCL20, CCL1, and IL-8 were reduced following knockdown of TLR10. Silencing of TLR10 resulted in increased viability of L. monocytogenes in both HT-29 and THP-1 cells. TLR10 was found to be predominantly expressed intracellularly in epithelia, and activation required viable L. monocytogenes. NF-κB activation was seen to require TLR2 in addition to TLR10. Taken together, these data indicate novel roles for TLR10 in sensing pathogenic infection in both the epithelium and macrophages and have identified L. monocytogenes as a source of ligand for the orphan receptor TLR10.

The colonic microbiota in health and disease

Abstract: Purpose of reviewDiverse research interests have converged on the gut microbiota because of its contribution to immune development, mucosal homeostasis and to the pathogenesis of a diversity of intestinal and extraintestinal disorders. Recent landmark findings are addressed here.Recent findingsThe i

Pellino3 ubiquitinates RIP2 and mediates Nod2-induced signaling and protective effects in colitis

Abstract: The E3 ubiquitin ligases that modify the kinase RIP2 downstream of the receptor Nod2 remain unclear. Moynagh and colleagues show that Pellino3 ubiquitinates RIP2 for Nod2-induced activation of the transcription factor NF-κB.

Natural Killer Cells Protect against Mucosal and Systemic Infection with the Enteric Pathogen Citrobacter rodentium

Abstract: Natural killer (NK) cells are traditionally considered in the context of tumor surveillance and viral defense, but their role in bacterial infections, particularly those caused by enteric pathogens, is less clear. C57BL/6 mice were orally gavaged with Citrobacter rodentium, a murine pathogen related to human diarrheagenic Escherichia coli. We used polyclonal anti-asialo GM1 antibody to actively deplete NK cells in vivo. Bioluminescent imaging and direct counts were used to follow infection. Flow cytometry and immunofluorescence microscopy were used to analyze immune responses. During C. rodentium infection, NK cells were recruited to mucosal tissues, where they expressed a diversity of immune-modulatory factors. Depletion of NK cells led to higher bacterial loads but less severe colonic inflammation, associated with reduced immune cell recruitment and lower cytokine levels. NK cell-depleted mice also developed disseminated systemic infection, unlike control infected mice. NK cells were also cytotoxic to C. rodentium in vitro.

A prospective feasibility study of sub-millisievert abdominopelvic CT using iterative reconstruction in Crohn’s disease

Abstract: Objective Iterative reconstruction (IR) allows diagnostic CT imaging with less radiation exposure than filtered back projection (FBP). We studied an IR low-dose CT abdomen/pelvis (LDCTAP) protocol, designed to image at an effective dose (ED) approximating 1 mSv in patients with Crohn’s disease (CD).

Prevalence and characterization of Clostridium perfringens from the faecal microbiota of elderly Irish subjects.

Abstract: The aim of this study was to investigate the diversity and composition of the intestinal microbiota of elderly subjects using a combination of culture-dependent techniques and 16S rRNA gene amplicon sequencing. The study was performed as part of the ELDERMET project, in which 368 faecal samples were assessed for viable numbers of Bifidobacterium spp., Lactobacillus spp. and Enterobacteriaceae on selective agar. However, the Bifidobacterium selective medium used also supported the growth of Clostridium perfringens, which appeared as distinct colonies and were subsequently characterized phenotypically and genotypically. All the isolates were confirmed as toxin biotype A producers. In addition, three isolates tested also had the genetic determinants for the β2 toxin. Of the 368 faecal samples assessed, C. perfringens was detected in 28 samples (7.6%). Moreover, C. perfringens was observed in samples from subjects in all the residence locations assessed but was most prevalent in subjects from long-stay residential care, with 71.4% of the samples (63.2% of the subjects) being from this residence location, and with a shedding level in excess of 10(6) c.f.u. (g faeces)(-1). Microbiota profiling revealed some significant compositional changes across both the family and genus taxonomic levels between the C. perfringens-positive and -negative datasets. Levels of culturable Bifidobacterium spp. and Lactobacillus spp. were significantly (P 10(6) c.f.u. (g faeces)(-1)] of C. perfringens in stool samples may be indicative of a less healthy microbiota in the intestine of elderly people in long-stay residential care.

Antimicrobials: Strategies for targeting obesity and metabolic health?

Abstract: Obesity is associated with a number of serious health consequences, including type 2 diabetes, cardiovascular disease and a variety of cancers among others and has been repeatedly shown to be associated with a higher risk of mortality. The relatively recent discovery that the composition and metabolic activity of the gut microbiota may affect the risk of developing obesity and related disorders has led to an explosion of interest in this distinct research field. A corollary of these findings would suggest that modulation of gut microbial populations can have beneficial effects with respect to controlling obesity. In this addendum, we summarize our recent data, showing that therapeutic manipulation of the microbiota using different antimicrobial strategies may be a useful approach for the management of obesity and metabolic conditions. In addition, we will explore some of the mechanisms that may contribute to microbiota-induced susceptibility to obesity and metabolic diseases.

Bcl-3 deficiency protects against dextran-sodium sulphate-induced colitis in the mouse.

Abstract: Bcl-3 is a member of the IκB family of proteins and is an essential negative regulator of Toll-like receptor-induced responses. Recently, a single nucleotide polymorphism associated with reduced Bcl-3 gene expression has been identified as a potential risk factor for Crohn's disease. Here we report that in contrast to the predictions of single nucleotide polymorphism (SNP) analysis, patients with Crohn's disease and ulcerative colitis demonstrate elevated Bcl-3 mRNA expression relative to healthy individuals. To explore further the potential role of Bcl-3 in inflammatory bowel disease (IBD), we used the dextran-sodium sulphate (DSS)-induced model of colitis in Bcl-3(-/-) mice. We found that Bcl-3(-/-) mice were less sensitive to DSS-induced colitis compared to wild-type controls and demonstrated no significant weight loss following treatment. Histological analysis revealed similar levels of oedema and leucocyte infiltration between DSS-treated wild-type and Bcl-3(-/-) mice, but showed that Bcl-3(-/-) mice retained colonic tissue architecture which was absent in wild-type mice following DSS treatment. Analysis of the expression of the proinflammatory cytokines interleukin (IL)-1β, tumour necrosis factor (TNF)-α and IL-6 revealed no significant differences between DSS-treated Bcl-3(-/-) and wild-type mice. Analysis of intestinal epithelial cell proliferation revealed enhanced proliferation in Bcl-3(-/-) mice, which correlated with preserved tissue architecture. Our results reveal that Bcl-3 has an important role in regulating intestinal epithelial cell proliferation and sensitivity to DSS-induced colitis which is distinct from its role as a negative regulator of inflammation.

Targeting the EP1 receptor reduces Fas ligand expression and increases the antitumor immune response in an in vivo model of colon cancer

Abstract: Despite studies demonstrating that inhibition of cyclooxygenase-2 (COX-2)-derived prostaglandin E2 (PGE2) has significant chemotherapeutic benefits in vitro and in vivo, inhibition of COX enzymes is associated with serious gastrointestinal and cardiovascular side effects, limiting the clinical utility of these drugs. PGE2 signals through four different receptors (EP1–EP4) and targeting individual receptor(s) may avoid these side effects, while retaining significant anticancer benefits. Here, we show that targeted inhibition of the EP1 receptor in the tumor cells and the tumor microenvironment resulted in the significant inhibition of tumor growth in vivo. Both dietary administration and direct injection of the EP1 receptor-specific antagonist, ONO8713, effectively reduced the growth of established CT26 tumors in BALB/c mice, with suppression of the EP1 receptor in the tumor cells alone less effective in reducing tumor growth. This antitumor effect was associated with reduced Fas ligand expression and attenuated tumor-induced immune suppression. In particular, tumor infiltration by CD4 1 CD25 1 Foxp3 1 regulatory T cells was decreased, whereas the cytotoxic activity of isolated splenocytes against CT26 cells was increased. F4/80 1 macrophage infiltration was also decreased; however, there was no change in macrophage phenotype. These findings suggest that the EP1 receptor represents a potential target for the treatment of colon cancer.

Digestion of epithelial tight junction proteins by the commensal Clostridium perfringens

Abstract: The enteric microbiota contributes to the pathogenesis of inflammatory bowel disease, but the pathways involved and bacterial participants may vary in different hosts. We previously reported that s...

Depth-Dependent Differences in Community Structure of the Human Colonic Microbiota in Health

Abstract: Objective: The aims of this study were to develop techniques for spatial microbial assessment in humans and to establish colonic luminal and mucosal spatial ecology, encompassing longitudinal and cross-sectional axes. Design: A microbiological protected specimen brush was used in conjunction with a biopsy forceps to sample the colon in nine healthy volunteers undergoing colonoscopy. Terminal Restriction Fragment Length Polymorphism analysis was used to determine the major variables in the spatial organization of the colonic microbiota. Results: Protected Specimen Brush sampling retrieved region-specific, uncontaminated samples that were enriched for bacterial DNA and depleted in human DNA when compared to biopsy samples. Terminal Restriction Fragment Length Polymorphism analysis revealed a segmentation of bacterial communities between the luminal brush and biopsy-associated ecological niches with little variability across the longitudinal axis of the colon and reduced diversity in brush samples. Conclusion: These results support the concept of a microbiota with little longitudinal variability but with some degree of segregation between luminal and mucosal communities.

Risk factors for hand injury in hurling: a cross-sectional study

Abstract: Objectives Hurling is Ireland9s national sport, played with a stick and ball; injury to the hand is common. A decrease in the proportion of head injury among emergency department (ED) presentations for hurling-related injury has coincided with voluntary use of helmet and face protection since 2003. A similar decrease in proportions has not occurred in hand injury. We aim to quantify hurling-related ED presentations and examine variables associated with injury. In particular, we were interested in comparing the occurrence of hand injury in those using head and face protection versus those who did not. Design This study utilised a retrospective cross-sectional study design. Setting This study took place at a university hospital ED over a 3-month period. Outcome measures A follow-up telephone interview was performed with 163 players aged ≥16 years to reflect voluntary versus obligatory helmet use. Results The hand was most often injured (n=85, 52.1%). Hand injury most commonly occurred from a blow of a hurley (n=104, 65%), and fracture was confirmed in 62% of cases. Two-thirds of players (66.3%) had multiple previous (1–5) hand injuries. Most patients 149 (91.4%) had tried commercially available hand protection, but only 4.9% used hand protection regularly. Univariate analysis showed a statistically significant association between wearing a helmet and faceguard and hand injury; OR 2.76 (95% CI 1.42 to 5.37) p=0.003. On further analysis adjusting simultaneously for age, prior injury, foul play and being struck by a hurley, this relationship remained significant (OR 3.15 95% CI 1.51 to 6.56, p=0.002). Conclusions We report that hurling-related hand injury is common. We noted the low uptake of hand protection. We found that hand injury was significantly associated with the use of helmet and faceguard protection, independent of the other factors studied. Further studies are warranted to develop strategies to minimise the occurrence of this injury.

In praise of the literary eponym--Henry V sign.

Abstract: The use of eponyms in medicine is often discouraged. However, the literary eponym should be an exception as it is not linked with many of the difficulties associated with conventional eponyms and offers descriptive brevity and accuracy. Here, we illustrate the point with Henry V sign, which will be familiar to many who have cared for patients in the terminal stage of illness.

Effects of the intestinal microbiota on behavior and brain biochemistry.

Abstract: Increasing evidence is emerging about the influence of the gut microbiota on the brain-gut axis, which has led to the concept of the brain-gut-enteric microbiota axis. In order to study this signaling mechanism, a number of approaches have been used involving animal models which examine the influence of the microbiota on brain function as discussed below. This review focuses on the influence of the gut microbiota on the gut-brain axis, bioactive metabolite production, and the use of probiotics to modulate metabolism and behavior.

Exopolysaccharide-producing bacteria, and uses thereof for protecting heart health

Abstract: An isolated Lactobacillus mucosae (DPC6426) strain deposited with the National Collection of Industrial and Marine Bacteria Limited (NCIMB) on 27th July 2012 under NCIMB Deposit Accession No. 42015.

A prospective study of cognitive performance in irritable bowel syndrome: visuospatial memory deficits as a stable feature

Abstract: Introduction The cognitive neurobiological model of IBS (Kennedy et al ., 2012), a disorder of the brain-gut axis, proposes that key pathophysiological features, such as altered hypothalamic-pituitary-adrenal (HPA) axis function, or heightened immune activity, may lead to impaired cognitive performance. Recently IBS patients were found to exhibit visuospatial memory deficits (Kennedy et al ., 2013). However, a prospective assessment is essential to confirm if cognitive dysfunction is a stable feature of IBS. Aims/Background To prospectively assess visuospatial memory performance in IBS, in comparison to disease controls Crohn9s diesase (CD] and healthy controls (HC). Method At baseline (Visit 1) and 6 months (Visit 2), IBS patients (baseline n=39; age (M): 28 yrs; IQ:105.5), matched CD patients (baseline n=18;age (M):32 yrs; IQ:103.4), and matched HC (baseline n=40;age (M):28 yrs; IQ:108.5), were assessed using a selection of cognitive tests from the CANTAB and Stroop test. Abdominal pain severity at time of testing was reported by IBS patients on a scale ranging from 0–100. Results At Visit 1 & 2, IBS patients displayed visuospatial memory deficits [Paired Associates Learning (PAL) test]; greater errors at the 6 pattern stage (baseline: p 0.05). Conclusion Visuospatial memory dysfunction is a stable feature of IBS. These results may inform future management of this debilitating disorder in which there is a great unmet medical need.