Post-infectious irritable bowel syndrome: Mechanistic insights into chronic disturbances following enteric infection

Gut microbiota and intestinal immunity-A crosstalk in irritable bowel syndrome

Irritable bowel syndrome (IBS), one of the most prevalent functional gastrointestinal disorders, is characterized by recurrent abdominal pain and abnormal defecation habits, resulting in a severe healthcare burden worldwide. The pathophysiological mechanisms of IBS are multi-factorially involved, including food antigens, visceral hypersensitivity reactions, and the brain-gut axis. Numerous studies have found that gut microbiota and intestinal mucosal immunity play an important role in the development of IBS in crosstalk with multiple mechanisms. Therefore, based on existing evidence, this paper elaborates that the damage and activation of intestinal mucosal immunity and the disturbance of gut microbiota are closely related to the progression of IBS. Combined with the application prospect, it also provides references for further in-depth exploration and clinical practice.

From-Toilet-to-Freezer: A Review on Requirements for an Automatic Protocol to Collect and Store Human Fecal Samples for Research Purposes

The composition, viability and metabolic functionality of intestinal microbiota play an important role in human health and disease. Studies on intestinal microbiota are often based on fecal samples, because these can be sampled in a non-invasive way, although procedures for sampling, processing and storage vary. This review presents factors to consider when developing an automated protocol for sampling, processing and storing fecal samples: donor inclusion criteria, urine-feces separation in smart toilets, homogenization, aliquoting, usage or type of buffer to dissolve and store fecal material, temperature and time for processing and storage and quality control. The lack of standardization and low-throughput of state-of-the-art fecal collection procedures promote a more automated protocol. Based on this review, an automated protocol is proposed. Fecal samples should be collected and immediately processed under anaerobic conditions at either room temperature (RT) for a maximum of 4 h or at 4 °C for no more than 24 h. Upon homogenization, preferably in the absence of added solvent to allow addition of a buffer of choice at a later stage, aliquots obtained should be stored at either -20 °C for up to a few months or -80 °C for a longer period-up to 2 years. Protocols for quality control should characterize microbial composition and viability as well as metabolic functionality.

The Role of Bovine Kappa-Casein Glycomacropeptide in Modulating the Microbiome and Inflammatory Responses of Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a common gastrointestinal disorder marked by chronic abdominal pain, bloating, and irregular bowel habits. Effective treatments are still actively sought. Kappa-casein glycomacropeptide (GMP), a milk-derived peptide, holds promise because it can modulate the gut microbiome, immune responses, gut motility, and barrier functions, as well as binding toxins. These properties align with the recognized pathophysiological aspects of IBS, including gut microbiota imbalances, immune system dysregulation, and altered gut barrier functions. This review delves into GMP's role in regulating the gut microbiome, accentuating its influence on bacterial populations and its potential to promote beneficial bacteria while inhibiting pathogenic varieties. It further investigates the gut microbial shifts observed in IBS patients and contemplates GMP's potential for restoring microbial equilibrium and overall gut health. The anti-inflammatory attributes of GMP, especially its impact on vital inflammatory markers and capacity to temper the low-grade inflammation present in IBS are also discussed. In addition, this review delves into current research on GMP's effects on gut motility and barrier integrity and examines the changes in gut motility and barrier function observed in IBS sufferers. The overarching goal is to assess the potential clinical utility of GMP in IBS management.

Triptolide attenuates irritable bowel syndrome via inhibiting ODC1

BACKGROUND

Irritable bowel syndrome (IBS) is a chronic disorder of the gut-brain axis with significant morbidity. Triptolide, an active compound extracted from Tripterygium wilfordii Hook F (TwHF), has been widely used as a major medicinal herb in the treatment of inflammatory disease.

METHODS

The chronic-acute combined stress (CAS) stimulation was used to establish IBS rat model. The model rats were then gavaged with triptolide. Forced swimming, marble-burying, fecal weight and abdominal withdrawal reflex (AWR) score were recorded. Pathologic changes in the ileal and colonic tissues were validated by hematoxylin and eosin staining. The inflammatory cytokines and Ornithine Decarboxylase-1 (ODC1) in the ileal and colonic tissues were performed by ELISA and WB.

RESULTS

Triptolide didn't have antidepressant- and antianxiety- effects in rats caused by CAS, but decreased fecal weight and AWR score. In addition, Triptolide reduced the release of IL-1, IL-6, and TNF-α and the expression of ODC1 in the ileum and colon.

CONCLUSION

The therapeutic efficacy of triptolide for IBS induced by CAS was revealed in this study, which may be related to the reduction of ODC1.

Emerging role of the gut microbiome in post-infectious irritable bowel syndrome: A literature review

Post-infectious irritable bowel syndrome (PI-IBS) is a particular type of IBS, with symptom onset after an acute episode of infectious gastroenteritis. Despite infectious disease resolution and clearance of the inciting pathogen agent, 10% of patients will develop PI-IBS. In susceptible individuals, the exposure to pathogenic organisms leads to a marked shift in the gut microbiota with prolonged changes in host-microbiota interactions. These changes can affect the gut-brain axis and the visceral sensitivity, disrupting the intestinal barrier, altering neuromuscular function, triggering persistent low inflammation, and sustaining the onset of IBS symptoms. There is no specific treatment strategy for PI-IBS. Different drug classes can be used to treat PI-IBS similar to patients with IBS in general, guided by their clinical symptoms. This review summarizes the current evidence for microbial dysbiosis in PI-IBS and analyzes the available data regarding the role of the microbiome in mediating the central and peripheral dysfunctions that lead to IBS symptoms. It also discusses the current state of evidence on therapies targeting the microbiome in the management of PI-IBS. The results of microbial modulation strategies used in relieving IBS symptomatology are encouraging. Several studies on PI-IBS animal models reported promising results. However, published data that describe the efficacy and safety of microbial targeted therapy in PI-IBS patients are scarce. Future research is required.

Antibiotics and Probiotics for Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a disorder of a gut-brain interaction characterised by abdominal pain and a change in stool form or frequency. Current symptom-based definitions and the classification of IBS promote heterogeneity amongst patients, meaning that there may be several different pathophysiological abnormalities leading to similar symptoms. Although our understanding of IBS is incomplete, there are several indicators that the microbiome may be involved in a subset of patients. Techniques including a faecal sample analysis, colonic biopsies, duodenal aspirates or surrogate markers, such as breath testing, have been used to examine the gut microbiota in individuals with IBS. Because of a lack of a clear definition of what constitutes a healthy gut microbiota, and the fact that alterations in gut microbiota have only been shown to be associated with IBS, a causal relationship is yet to be established. We discuss several hypotheses as to how dysbiosis may be responsible for IBS symptoms, as well as potential treatment strategies. We review the current evidence for the use of antibiotics and probiotics to alter the microbiome in an attempt to improve IBS symptoms. Rifaximin, a non-absorbable antibiotic, is the most studied antibiotic and has now been licensed for use in IBS with diarrhoea in the USA, but the drug remains unavailable in many countries for this indication. Current evidence also suggests that certain probiotics, including Lactobacillus plantarum DSM 9843 and Bifidobacterium bifidum MIMBb75, may be efficacious in some patients with IBS. Finally, we describe the future challenges facing us in our attempt to modulate the microbiome to treat IBS.

Irritable Bowel Syndrome and the Gut Microbiome: A Comprehensive Review

Irritable Bowel Syndrome (IBS) is a functional disorder of the gastrointestinal tract characterized by abdominal pain and altered bowel habits. It has a prevalence of 10 to 25% in the United States and has a high disease burden, as evidenced by reduced quality of life, decreased work productivity and increased healthcare utilization and costs. IBS has been associated with several intra-intestinal and extra-intestinal conditions, including psychiatric comorbidities. Although the pathophysiology of IBS has not been fully elucidated, it involves dysregulation of communication between the brain and gut (brain–gut axis) which is associated with alterations in intestinal motility, gut permeability, visceral hypersensitivity and gut microbiota composition. The purpose of this article is to review the role the gut microbiota plays in the pathophysiology of IBS, understand factors that affect the gut microbiome and explore the microbiome as a target of treatment.

Fermented Vegetables as a Potential Treatment for Irritable Bowel Syndrome

Foods and supplements containing microorganisms with expected beneficial effects are increasingly investigated and utilized in the treatment of human illness, including irritable bowel syndrome (IBS). Research points to a prominent role of gut dysbiosis in the multiple aberrations in gastrointestinal function, immune balance, and mental health seen in IBS. The proposition of the current Perspective is that fermented vegetable foods, in combination with a healthy and stable diet, may be particularly useful for addressing these disturbances. This is based on the recognition that plants and their associated microorganisms have contributed to shaping human microbiota and adaptation over evolutionary time. In particular, lactic acid bacteria with immunomodulatory, antipathogenic, and digestive properties are prevalent in products such as sauerkraut and kimchi. Additionally, by adjusting the salt content and fermentation time, products with a microbial and therapeutic potential beyond that of regular ferments could potentially be produced. Although more clinical data are required to make firm assertions, the low-risk profile, combined with biological considerations and reasoning and considerable circumstantial and anecdotal evidence, indicate that fermented vegetables are worthy of consideration by health professionals and patients dealing with IBS-related issues. To maximize microbial diversity and limit the risk of adverse effects, small doses of multiple products, containing different combinations of traditionally fermented vegetables and/or fruits, is suggested for experimental research and care.

Ameliorating effects of electroacupuncture on the low-grade intestinal inflammation in rat model of diarrhea-predominant irritable bowel syndrome

BACKGROUND AND AIM

We aim to investigate the effects and mechanisms of electroacupuncture (EA) at ST25 and ST37 on the intestinal low-grade inflammation (LGI) in rat model of Diarrhea-predominant irritable bowel syndrome (IBS-D).

METHODS

IBS-D model rats were established by acetic acid enema combined with restraint and tail clamping. Before EA intervention, they were divided into three groups: blank 1 group, blank 2 group, and IBS-D model group. Diarrhea symptoms and visceral pain sensitivity were evaluated. After constructed the model successfully, the remaining IBS-D model group rats were randomly divided into model group and EA group. Local intestinal inflammation (HE staining), changes of intestinal mucosa (occludin protein and microvascular diameter) were evaluated. Differences between two groups were compared using t-test or Mann-Whitney U-test. Differences among more than two groups were compared using one-way ANOVA or Kruskal-Wallis test.

RESULTS

After modeling, the results of HE staining in intestinal tract of IBS-D model rats showed LGI. Compared with the model group, 4 h fecal moisture content (diarrhea index) and the AWR score were decreased in the EA group. The results of HE in EA group showed that the infiltration of intestinal inflammatory cells were alleviated. Additionally, EA significantly upregulated the expression of occludin protein and partially dilated the intestinal microvascular diameter. Pearson correlation analysis showed that the symptoms of IBS-D rats were correlated with the changes of intestinal mucosa.

CONCLUSION

EA may treat intestinal LGI in IBS-D rats by upregulating the expression of occludin protein and dilating the intestinal microvascular diameter.

Gut Microbiota Shifting in Irritable Bowel Syndrome: The Mysterious Role of Blastocystis sp

Irritable bowel syndrome (IBS) is a chronic disorder, which its causative agent is not completely clear; however, the interaction between microorganisms and gastrointestinal (GI) epithelial cells plays a critical role in the development of IBS and presenting symptoms. During recent decades, many studies have highlighted the high prevalence of Blastocystis sp. in patients with IBS and suggested a probable role for this protist in this disease. Recent studies have documented changes in the gut microbiota composition in patients with IBS regarding the presence of Blastocystis sp., but it is not clear that either disturbance of the gut during GI disorders is a favorable condition for Blastocystis sp. colonization or the presence of this protist may lead to alteration in the gut microbiota in IBS patients. In this review, we comprehensively gather and discuss scientific findings covering the role of Blastocystis sp. in IBS via gut microbiota shifting.

Pain Management and COVID-19: A Latin American Perspective

Vaccinations and therapeutics have been developed for COVID-19, but vaccine uptake varies markedly among countries. Public health responses have also varied, in particular, with lockdown efforts and school closing. All over the world, the pandemic exposed healthcare and economic weaknesses. COVID-19 exacerbated mental health issues by exposing the population to prolonged periods of fear, anxiety, financial stress, psychological uncertainties, and sometimes isolation from even family and friends. Chronic pain patients have been disproportionately affected. The pandemic-associated stresses may have exacerbated their already painful symptoms while at the same time interrupting their access to care. The ramifications of the COVID-19 post-viral syndrome (“long COVID-19”) are not yet known. COVID-19 viral infection has been associated with neuropathic pain symptoms. Tele-triage and telehealth applications can help manage chronic pain patients in the COVID-19 era, but many interventional procedures, injections, or other treatments have been delayed. The role of palliative care for patients with terminal cases of infection must be re-examined. Palliative care is a relatively new medical specialty and allows terminally ill patients to die in as much comfort and peace as can be afforded to them. More training in palliative care for all clinicians is urgently needed. COVID-19 exposed much that is wrong or weak or inadequate in our healthcare systems, but it also allowed us to embrace new technologies and develop better systems to manage the challenge of a pandemic.

Beyond Immunity: Underappreciated Functions of Intestinal Macrophages

The gastrointestinal tract hosts the largest compartment of macrophages in the body, where they serve as mediators of host defense and immunity. Seeded in the complex tissue-environment of the gut, an array of both hematopoietic and non-hematopoietic cells forms their immediate neighborhood. Emerging data demonstrate that the functional diversity of intestinal macrophages reaches beyond classical immunity and includes underappreciated non-immune functions. In this review, we discuss recent advances in research on intestinal macrophage heterogeneity, with a particular focus on how non-immune functions of macrophages impact tissue homeostasis and function. We delve into the strategic localization of distinct gut macrophage populations, describe the potential factors that regulate their identity and functional heterogeneity within these locations, and provide open questions that we hope will inspire research dedicated to elucidating a holistic view on macrophage-tissue cell interactions in the body's largest mucosal organ.

Resource Competition and Host Feedbacks Underlie Regime Shifts in Gut Microbiota

AbstractThe spread of an enteric pathogen in the human gut depends on many interacting factors, including pathogen exposure, diet, host gut environment, and host microbiota, but how these factors jointly influence infection outcomes remains poorly characterized. Here we develop a model of host-mediated resource competition between mutualistic and pathogenic taxa in the gut that aims to explain why similar hosts, exposed to the same pathogen, can have such different infection outcomes. Our model successfully reproduces several empirically observed phenomena related to transitions between healthy and infected states, including (1) the nonlinear relationship between pathogen inoculum size and infection persistence, (2) the elevated risk of chronic infection during or after treatment with broad-spectrum antibiotics, (3) the resolution of gut dysbiosis with fecal microbiota transplants, and (4) the potential protection from infection conferred by probiotics. We then use the model to explore how host-mediated interventions-namely, shifts in the supply rates of electron donors (e.g., dietary fiber) and respiratory electron acceptors (e.g., oxygen)-can potentially be used to direct gut community assembly. Our study demonstrates how resource competition and ecological feedbacks between the host and the gut microbiota can be critical determinants of human health outcomes. We identify several testable model predictions ready for experimental validation.

You Talking to Me? Says the Enteric Nervous System (ENS) to the Microbe. How Intestinal Microbes Interact with the ENS

Mammalian organisms form intimate interfaces with commensal and pathogenic gut microorganisms. Increasing evidence suggests a close interaction between gut microorganisms and the enteric nervous system (ENS), as the first interface to the central nervous system. Each microorganism can exert a different effect on the ENS, including phenotypical neuronal changes or the induction of chemical transmitters that interact with ENS neurons. Some pathogenic bacteria take advantage of the ENS to create a more suitable environment for their growth or to promote the effects of their toxins. In addition, some commensal bacteria can affect the central nervous system (CNS) by locally interacting with the ENS. From the current knowledge emerges an interesting field that may shape future concepts on the pathogen-host synergic interaction. The aim of this narrative review is to report the current findings regarding the inter-relationships between bacteria, viruses, and parasites and the ENS.

Shaoyao-Gancao Decoction Relieves Visceral Hyperalgesia in TNBS-Induced Postinflammatory Irritable Bowel Syndrome via Inactivating Transient Receptor Potential Vanilloid Type 1 and Reducing Serotonin Synthesis

Postinflammatory irritable bowel syndrome (PI-IBS) is a common functional gastrointestinal disorder, which is characterized by abdominal pain, low-grade inflammation, and visceral hypersensitivity. Shaoyao-Gancao decoction (SGD) has been used to improve the clinical symptoms of abdominal spasmodic pain accompanying acute gastroenteritis, but the underlying therapeutic mechanism has not been fully elucidated. In the present study, a rat model of PI-IBS was established via rectal administration of TNBS. Rats were scored daily for 28 days using disease activity index (DAI). Abdominal withdrawal reflex (AWR) was used to measure the pain threshold. After SGD (6.25, 12.5, and 25 g/kg/d) treatment for 14 days, rat colonic tissue was collected for histopathological grading, enterochromaffin (EC) cell count, and 5-HT content measurement. RT-qPCR and western blot analyses were employed to detect the gene and protein level of tryptophan hydroxylase (TPH), serotonin reuptake transporter (SERT), and transient receptor potential vanilloid 1 (TRPV1). To further validate the effect of SGD on TRPV1, another experiment was performed in cells. The results revealed that visceral hyperalgesia, reflected by increased DAI, AWR, pathological injury score, 5-HT content, and EC cell count in PI-IBS rats, was significantly ameliorated by SGD. In cells, SGD markedly inhibited the expression and function of TRPV1. Moreover, the expression levels of TPH were also repressed by SGD. The findings of the present study indicated that the therapeutic effect of SGD on visceral hyperalgesia may be closely associated with the regulatory role of TRPV1 and 5-HT signaling pathways.

Adrenergic Signaling in Muscularis Macrophages Limits Infection-Induced Neuronal Loss

Enteric-associated neurons (EANs) are closely associated with immune cells and continuously monitor and modulate homeostatic intestinal functions, including motility and nutrient sensing. Bidirectional interactions between neuronal and immune cells are altered during disease processes such as neurodegeneration or irritable bowel syndrome. We investigated the effects of infection-induced inflammation on intrinsic EANs (iEANs) and the role of intestinal muscularis macrophages (MMs) in this context. Using murine models of enteric infections, we observed long-term gastrointestinal symptoms, including reduced motility and loss of excitatory iEANs, which was mediated by a Nlrp6- and Casp11-dependent mechanism, depended on infection history, and could be reversed by manipulation of the microbiota. MMs responded to luminal infection by upregulating a neuroprotective program via β₂-adrenergic receptor (β₂-AR) signaling and mediated neuronal protection through an arginase 1-polyamine axis. Our results identify a mechanism of neuronal death post-infection and point to a role for tissue-resident MMs in limiting neuronal damage.

Fecal dysbiosis associated with colonic hypersensitivity and behavioral alterations in chronically Blastocystis-infected rats

BACKGROUND

Infectious gastroenteritis is a risk factor for the development of post-infectious Irritable Bowel Syndrome (PI-IBS). Recent clinical studies reported a higher prevalence of the intestinal parasite Blastocystis in IBS patients. Using a rat model, we investigated the possible association between Blastocystis infection, colonic hypersensitivity (CHS), behavioral disturbances and gut microbiota changes.

METHODS

Rats were orally infected with Blastocystis subtype 4 (ST4) cysts, isolated from human stool samples. Colonic sensitivity was assessed by colorectal distension and animal behavior with an automatic behavior recognition system (PhenoTyper), the Elevated Plus Maze test and the Forced Swimming tests. Feces were collected at different time points after infection to study microbiota composition by 16 S rRNA amplicon sequencing and for short-chain fatty acid (SFCA) analysis.

RESULTS

Blastocystis-infected animals had non-inflammatory CHS with increased serine protease activity. Infection was also associated with anxiety- and depressive-like behaviors. Analysis of fecal microbiota composition showed an increase in bacterial richness associated with altered microbiota composition. These changes included an increase in the relative abundance of Oscillospira and a decrease in Clostridium, which seem to be associated with lower levels of SCFAs in the feces from infected rats.

CONCLUSIONS

Our findings suggest that experimental infection of rats with Blastocystis mimics IBS symptoms with the establishment of CHS related to microbiota and metabolic shifts.

Nonpharmacologic options for treating irritable bowel syndrome

Irritable bowel syndrome (IBS) is a chronic functional disorder with no organic cause. Risk factors are multifactorial and treatment typically consists of antimotility or stimulant laxatives and antidepressants. This article reviews several newer areas of interest: probiotics, fecal microbiota transplant, a low FODMAP diet, and cognitive behavioral therapy.

The Microbiome and Irritable Bowel Syndrome - A Review on the Pathophysiology, Current Research and Future Therapy

Irritable bowel syndrome (IBS) is a functional disorder which affects a large proportion of the population globally. The precise etiology of IBS is still unknown, although consensus understanding proposes IBS to be of multifactorial origin with yet undefined subtypes. Genetic and epigenetic factors, stress-related nervous and endocrine systems, immune dysregulation and the brain-gut axis seem to be contributing factors that predispose individuals to IBS. In addition to food hypersensitivity, toxins and adverse life events, chronic infections and dysbiotic gut microbiota have been suggested to trigger IBS symptoms in tandem with the predisposing factors. This review will summarize the pathophysiology of IBS and the role of gut microbiota in relation to IBS. Current methodologies for microbiome studies in IBS such as genome sequencing, metagenomics, culturomics and animal models will be discussed. The myriad of therapy options such as immunoglobulins (immune-based therapy), probiotics and prebiotics, dietary modifications including FODMAP restriction diet and gluten-free diet, as well as fecal transplantation will be reviewed. Finally this review will highlight future directions in IBS therapy research, including identification of new molecular targets, application of 3-D gut model, gut-on-a-chip and personalized therapy.

Challenges in IBD Research: Environmental Triggers

Environmental triggers is part of five focus areas of the Challenges in IBD research document, which also includes preclinical human IBD mechanisms, novel technologies, precision medicine and pragmatic clinical research. The Challenges in IBD research document provides a comprehensive overview of current gaps in inflammatory bowel diseases (IBD) research and delivers actionable approaches to address them. It is the result of a multidisciplinary input from scientists, clinicians, patients, and funders, and represents a valuable resource for patient centric research prioritization. In particular, the environmental triggers section is focused on the main research gaps in elucidating causality of environmental factors in IBD. Research gaps were identified in: 1) epidemiology of exposures; 2) identification of signatures of biological response to exposures; and 3) mechanisms of how environmental exposures drive IBD. To address these gaps, the implementation of longitudinal prospective studies to determine disease evolution and identify sub-clinical changes in response to exposures is proposed. This can help define critical windows of vulnerability and risk prediction. In addition, systems biology analysis and in silico modeling were proposed as approaches to integrate the IBD exposome for the identification of biological signatures of response to exposures, and to develop prediction models of the effects of environmental factors in driving disease activity and response to therapy. This research could lead to identification of biomarkers of exposures and new modalities for therapeutic intervention. Finally, hypothesis-driven mechanistic studies to understand gene-environment interactions and to validate causality of priority factors should be performed to determine how environment influences clinical outcomes.

Saponins regulate intestinal inflammation in colon cancer and IBD

The saponins are natural surface-active glycosides which are the principal components of many popular herbal medicinal plants such as ginseng, astragalus, and bupleurum. Recent studies have suggested that saponins can exert strong anti-inflammatory effects and induce immune homeostasis in many diseases. Intestinal-inflammation-related digestive diseases include inflammatory bowel disease (IBD), irritable bowel syndrome, intestinal ischemia-reperfusion injury, necrotizing enterocolitis and radiation proctitis, as well as intestinal inflammation caused by nonsteroidal anti-inflammatory drugs. The pathogenesis of these diseases is poorly understood, and the patients with these diseases suffer from mental stress and physical pain, while their families (and society) experience heavy economic losses. Results from animal experiments suggest that saponins can suppress intestinal inflammation, promote intestinal barrier repair, maintain the diversity of the intestinal flora, and decrease the incidence rate of colon-inflammation-related colon cancer. In this review, we discuss new findings regarding the effects of saponins on intestinal inflammation and digestive diseases with intestinal inflammation. In addition, we provide a summary of the underlying mechanism for saponins-induced treatment on intestinal-inflammation-related disease.

Painful neurotrophins and their role in visceral pain

Beyond their well-known role in embryonic development of the central and peripheral nervous system, neurotrophins, particularly nerve growth factor and brain-derived neurotrophic factor, exert an essential role in pain production and sensitization. This has mainly been studied within the framework of somatic pain, and even antibodies (tanezumab and fasinumab) have recently been developed for their use in chronic somatic painful conditions, such as osteoarthritis or low back pain. However, data suggest that neurotrophins also exert an important role in the occurrence of visceral pain and visceral sensitization. Visceral pain is a distressing symptom that prompts many consultations and is typically encountered in both 'organic' (generally inflammatory) and 'functional' (displaying no obvious structural changes in routine clinical evaluations) disorders of the gut, such as inflammatory bowel disease and irritable bowel syndrome, respectively. The present review provides a summary of neurotrophins as a molecular family and their role in pain in general and addresses recent investigations of the involvement of nerve growth factor and brain-derived neurotrophic factor in visceral pain, particularly that associated with inflammatory bowel disease and irritable bowel syndrome.

Irritable bowel syndrome and colonic diverticular disease: overlapping symptoms and overlapping therapeutic approaches

PURPOSE OF REVIEW

Irritable bowel syndrome (IBS) is a common symptomatic disorder in the Western world and colonic diverticula are also prevalent; however, relationships between IBS-type symptoms and diverticula have been a source of much debate. Our goal was to reassess these relationships in the light of new data.

RECENT FINDINGS

On removing from consideration clinical scenarios which are directly related to diverticula (i.e., diverticulitis, diverticular hemorrhage, and complications of diverticulitis, such as stricture and fistula), relationships between IBS and diverticula can be seen to revolve around a number of questions. First, are IBS and symptomatic uncomplicated diverticular disease (SUDD) the same condition? Or, in other words is SUDD no more than IBS in an individual who just happens to have diverticula? Although coincident IBS and diverticula inevitably do occur there is some evidence to indicate that SUDD may be somewhat distinctive with SUDD being characterized by more frequent and severe pain. Second, and analogous to interactions between IBS and inflammatory bowel disease or celiac disease, can an episode of acute diverticulitis lead to the de novo development of IBS? There is now epidemiological and pathophysiological evidence to support this occurrence.

SUMMARY

Although relationships between uncomplicated diverticular disease and IBS have been reexamined their status remains unclear. As yet, however, none of the newer concepts related to this relationship have led to new therapeutic approaches in IBS or diverticular disease.

The Effect of Prim-O-Glucosylcimifugin on Tryptase-Induced Intestinal Barrier Dysfunction in Caco-2 Cells

The intestinal barrier dysfunction is a critical pathological change in irritable bowel syndrome (IBS). The objective of this study was to evaluate the effect of Prim-O-glucosylcimifugin (POG) on intestinal barrier dysfunction and reveal possible molecular mechanisms. Human colon adenocarcinoma cell line (Caco-2) cell monolayers induced by tryptase (TRYP) were used to establish an intestinal barrier dysfunction model. Caco-2 cell monolayers from both functional and dysfunctional samples were treated with POG (30, 60 and 120 µg/mL) for 2, 8, 24, 36, 48 and 72 h. The Caco-2 cell monolayers were assessed by measurement of trans-epithelial electrical resistance (TEER) and percentage of fluorescein permeation (PFP). The expression of Protease Activated Receptor 2 (PAR-2) and myosin light chain kinase (MLCK) mRNA was analyzed by RT-PCR and the level of Zonula Occludens-1 (ZO-1) protein expression was determined by Western blot. In addition, the impact of POG on the distribution of the tight juction protein of Occludin was performed by immunofluorescence. Our results showed that POG elevated the TEER and decreased the PFP of the functional Caco-2 cell monolayers, as well as the dysfunctional Caco-2 cell monolayers. Furthermore, POG inhibited the expression of PAR-2 mRNA and MLCK mRNA and increased the level of ZO-1 protein expression in dysfunctional Caco-2 cells. The distribution of the Occludin proteins was ameliorated simultaneously. This study demonstrates that POG can enhance the intestinal barrier function of Caco-2 cell monolayers by inhibiting the expression of PAR-2 and MLCK and up-regulating the expression of ZO-1 protein, and ameliorated the distribution of Occludin protein.

Role of Gut Microbiota-Gut Hormone Axis in the Pathophysiology of Functional Gastrointestinal Disorders

Gut microbiota exert a pivotal influence on various functions including gastrointestinal (GI) motility, metabolism, nutrition, immunity, and the neuroendocrine system in the host. These effects are mediated by not only short-chain fatty acids produced by microbiota but also gut hormones and inflammatory signaling by enteroendocrine and immune cells under the influence of the microbiota. GI motility is orchestrated by the enteric nervous system and hormonal networks, and disturbance of GI motility plays an important role in the pathophysiology of functional gastrointestinal disorders (FGIDs). In this context, microbiota-associated mediators are considered to act on specific receptors, thus affecting the enteric nervous system and, subsequently, GI motility. Thus, the pathophysiology of FGIDs is based on alterations of the gut microbiota/gut hormone axis, which have crucial effects on GI motility.

Association between gastrointestinal motility and macrophage/mast cell distribution in mice during the healing stage after DSS‑induced colitis

Irritable bowel syndrome (IBS) frequently occurs after infectious colitis or inflammatory bowel disease in patients with complete remission. This suggests that post‑inflammation‑associated factors may serve a role in the pathophysiology of IBS; however, the mechanism responsible remains unclear. In the present study, the involvement of macrophages and mast cells in alteration of gastrointestinal (GI) motility was investigated in mice in the remission stage after acute colitis. C57BL/6 mice were administered 2% dextran sulfate sodium in drinking water for 5 days and their intestinal tissues were investigated at intervals for up to 24 weeks. Expression of the mannose receptor (MR) and tryptase was examined by immunohistochemistry, and the GI transit time (GITT) was measured by administration of carmine red solution. A minimal degree of inflammatory cell infiltration persisted in the colon and also the small intestine of mice in remission after colitis and the GITT was significantly shorter. The number of muscularis MR‑positive macrophages was significantly increased in the small intestine of mice in remission after colitis and negatively correlated with GITT. Furthermore, results indicated that the number of muscularis tryptase‑positive mast cells was significantly increased throughout the intestine of mice during the healing process after colitis and was positively correlated with GITT. The present findings suggested an increased number of macrophages and/or mast cells in the intestinal muscular layer may be associated with the pathophysiology of GI dysmotility after colitis.

Clostridium difficile-related postinfectious IBS: a case of enteroglial microbiological stalking and/or the solution of a conundrum?

Post-infectious irritable bowel syndrome is a well-defined pathological entity that develops in about one-third of subjects after an acute infection (bacterial, viral) or parasitic infestation. Only recently it has been documented that an high incidence of post-infectious irritable bowel syndrome occurs after Clostridium difficile infection. However, until now it is not known why in some patients recovered from this infection the gastrointestinal disturbances persist for months or years. Based on our in vitro studies on enteric glial cells exposed to the effects of C. difficile toxin B, we hypothesize that persistence of symptoms up to the development of irritable bowel syndrome might be due to a disturbance/impairment of the correct functions of the enteroglial intestinal network.

Current insights into the innate immune system dysfunction in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a functional bowel disorder associated with abdominal pain and alterations in bowel habits. The presence of IBS greatly impairs patients' quality of life and imposes a high economic burden on the community; thus, there is intense pressure to reveal its elusive pathogenesis. Many etiological mechanisms have been implicated, but the pathophysiology of the syndrome remains unclear. As a result, novel drug development has been slow and no pharmacological intervention is universally accepted. A growing evidence implicates the role of low-grade inflammation and innate immune system dysfunction, although contradictory results have frequently been presented. Mast cells (MC), eosinophils and other key immune cells together with their mediators seem to play an important role, at least in subgroups of IBS patients. Cytokine imbalance in the systematic circulation and in the intestinal mucosa may also characterize IBS presentation. Toll-like receptors and their emerging role in pathogen recognition have also been highlighted recently, as dysregulation has been reported to occur in patients with IBS. This review summarizes the current knowledge regarding the involvement of any immunological alteration in the development of IBS. There is substantial evidence to support innate immune system dysfunction in several IBS phenotypes, but additional studies are required to better clarify the underlying pathogenetic pathways. IBS heterogeneity could potentially be attributed to multiple causes that lead to different disease phenotypes, thus explaining the variability found between study results.

Inflammatory cell distribution in colon mucosa as a new tool for diagnosis of irritable bowel syndrome: A promising pilot study

BACKGROUND

Currently, there are no histological criteria to diagnose irritable bowel syndrome (IBS). Our aims were (i) to examine the distribution of inflammatory cells in the colon of healthy and IBS subjects and (ii) to find histological diagnosis criteria for IBS.

METHODS

Colonic biopsies were taken from four distinct regions of the colon from 20 controls (HC) and 11 patients with IBS (4 with constipation (IBS-C) and 7 with diarrhea (IBS-D) and embedded in paraffin. Macrophages, mast cells, eosinophils, and T lymphocytes were immunostained and positive cells counted.

KEY RESULTS

In both HC and IBS patients, global cellularity decreased from the cecum to the rectum (P < .01) which is attributed to reduced number of macrophages (P < .05) and eosinophils (P < .001) but not T cells. Mast cells were reduced in IBS (P < .05) but not in HC, particularly in IBS-D (P < .05). Results showed higher number of macrophages in the left colon of IBS subjects than HC (P < .05).

CONCLUSION & INFERENCES

Here we report a decreasing gradient of immune cells from the cecum to the rectum of the human colon. Although global cellularity cannot be used to distinguish between IBS and HC, closer analysis of macrophages and mast cells may be useful markers to confirm IBS histologically and to differentiate between IBS-C and IBS-D when clinical presentation alternates between constipation and diarrhoea. This pilot study remains to be confirmed with greater number of patients.

Stereotaxic Exposure of the Central Nucleus of the Amygdala to Corticosterone Increases Colonic Permeability and Reduces Nerve-Mediated Active Ion Transport in Rats

Background: Irritable bowel syndrome (IBS) is characterized by visceral pain and abnormal bowel habits that are worsened during stress. Evidence also suggests altered intestinal barrier function in IBS. Previously, we demonstrated that stereotaxic application of the stress hormone corticosterone (CORT) onto the central nucleus of the amygdala (CeA) induces colonic hyperalgesia and anxiety-like behavior in a rat model, however the effect on intestinal permeability and mucosal function remain to be evaluated. Methods: Male Fischer 344 rats underwent bilateral stereotaxic implantation of CORT or inert cholesterol (CHOL)-containing micropellets (30 μg) onto the dorsal margin of the CeA. Seven days later, colonic tissue was isolated to assess tissue permeability in modified Ussing chambers via transepithelial electrical resistance (TEER) and macromolecular flux of horseradish peroxidase (HRP). Secretory responses to electrical field stimulation (EFS) of submucosal enteric nerves as well as activation with forskolin were used to assess movements of ions across the isolated colonic tissues. In a separate cohort, colonic histology, and mast cell infiltration was assessed. Key Results: Compared to CHOL-implanted controls, we determined that exposing the CeA to elevated levels of CORT significantly increased macromolecular flux across the colonic epithelial layer without changing TEER. Nerve-mediated but not cAMP-mediated active transport was inhibited in response to elevated amygdala CORT. There were no histological changes or increases in mast cell infiltration within colonic tissue from CORT treated animals. Conclusion and Inferences: These observations support a novel role for the CeA as a modulator of nerve-mediated colonic epithelial function.

First genotyping of Blastocystis sp. in dairy, meat, and cashmere goats in northwestern China

Blastocystis is one of the most common parasites inhabiting in small intestines of human and animals. Although its pathogenicity has been remaining controversial, the possibility of zoonotic transmission between human and animals was recognized. The goat was one of the most important economic animals supplying people with cashmere, meat, and dairy products. However, few studies were to investigate Blastocystis infection in goats. A total of 789 faecal specimens of goats (including 362 of dairy, 193 of meat and 234 of cashmere goats) were collected from multiple regions of Shaanxi province in northwestern China to investigate the colonization frequency and subtypes of Blastocystis, and to assess the zoonotic potential of these goats. The respective colonization frequencies of Blastocystis in dairy, meat and cashmere goats were 54.1% (196/362), 40.4% (78/193) and 78.6% (184/234). The prevalence of Blastocystis in pre-weaned (0-2-month) goats was significantly lower than that in goats of other age groups, and the highest colonization was observed in goats of 7-11-month age group. Sequence analysis of Blastocystis positive samples indicated the presence of seven subtypes in these goats, including six known subtypes (STs1, 3, 4, 5, 10, 14) and one possible novel subtype (isolate Sd26), with the subtype 10 as the predominant one. Additionally, zoonotic subtypes were found in dairy (ST1, ST3 and ST5) and cashmere (ST4 and ST5) goats, but not detected in meat goats. These results showed that Blastocystis is highly prevalent, widely distributed and genetically diverse in goats in Shaanxi province, northwestern China, and zoonotic potential of dairy and cashmere goats to transmit Blastocystis.

Comparison of geographic distributions of Irritable Bowel Syndrome with Inflammatory Bowel Disease fail to support common evolutionary roots: Irritable Bowel Syndrome and Inflammatory Bowel Diseases are not related by evolution

Irritable Bowel Syndrome (IBS) shares overlapping symptoms and some features of pathogenesis with Inflammatory Bowel Diseases (IBD: Crohn's disease [CD], and Ulcerative Colitis [UC]). Geographic markers such as latitude/sunshine and more recently lactase population distributions are found to be correlated with IBD. As a result of clinical and pathogenic similarities between the 2 conditions, some authorities questioned whether a connection exists between them. We compare IBS directly with IBD, and indirectly with geographic markers associated with IBD, in order to evaluate possible evolutionary links between IBS and IBD. Similar correlations may link IBS as a precursor to IBD and possibly other conditions which are geographically connected with IBD. Data from four systematic reviews on IBD incidence and prevalence, IBS prevalence, and lactase distributions were included. Pearson's correlations were used for comparisons, with IBD values log-transformed because of skewed distribution. The articles provided 18-28 complete set of national data. Direct comparison between IBS and IBD showed no significant correlations (r = -0.14, r = -0.06 for CD and UC prevalence, r = -0.10 for CD incidence). Indirect comparisons also failed to show correlations of IBS with lactase distributions (r = -0.17), sunshine (r = -0.2) or latitude (r = 0.097); however, there was significant correlation between lactase distributions and CD incidence (r = -0.84), prevalence (r = -0.55) and UC prevalence (r = -0.59). Both sunshine (r= -0.53) and latitude (r = 0.58) are also significantly related to CD incidence. It is concluded that IBS and IBD do not follow similar global geographic patterns. This suggests a lack of an evolutionary genetic background coincident with emergence of lactase persistence. As well, vitamin D has no obvious impact on development of IBS. Similarities with IBD may result from sub groups (not yet identified) within the current Rome criteria of IBS. Alternatively limited intestinal gut-brain responses to host microbial interactions may result in similar overlap features in both.

Adherent-Invasive E. coli enhances colonic hypersensitivity and P2X receptors expression during post-infectious period

Irritable Bowel Syndrome (IBS) and Inflammatory Bowel Disease (IBD) are related gastrointestinal disorders characterized by abdominal pain associated with colonic hypersensitivity (CHS). Studies in humans have reported an abnormal colonization of Adherent-Invasive E. coli (AIEC) in the ileum of Crohn's disease (CD) patients associated with overexpression of the bacterial colonizing receptor CEACAM6. The aim of the present study was to investigate whether AIEC reference strain LF82 could induce intestinal impairment during infectious and/or post-infectious periods and subsequently the development of CHS. Transgenic mice overexpressing human CEACAM6 protein (TG) and their wild-type littermates were gavaged by CD-associated AIEC bacteria (reference strain LF82) or PBS for 3 d. Colonic hypersensitivity was assessed by colorectal distension (CRD) test during infectious (D4) and post-infectious periods (D21). Several markers of intestinal inflammation were monitored and the colonic expression of purinergic P2X receptors was quantified. At D4, an increased visceromotor response (VMR) to the CRD test was observed in TG mice infected with CD-associated AIEC LF82 in comparison with non-infected TG mice and persisted in a subgroup of infected animals at D21 after bacteria clearance. Increased VMR was associated with low-grade intestinal inflammation, increased intestinal permeability and expression of P2X 3, 4 and 7. This study shows that certain susceptible hosts infected with CD-associated AIEC bacteria can develop persistent CHS associated with low-grade inflammation and increased P2X receptors expression. Thus, CD-associated AIEC infection in CEACAM6 transgenic mice could be used as a novel post-infectious mouse model mimicking quiescent IBD with IBS-like symptoms such as visceral pain.

Post-Infectious Irritable Bowel Syndrome

PURPOSE OF REVIEW

Post-infectious irritable bowel syndrome (PI-IBS) is characterized by persistent abdominal pain and diarrhea, typically following an episode of infectious gastroenteritis. The mechanisms that underlie IBS-D remain elusive, but PI-IBS provides a mechanistic model of this disorder. This review provides an up-to-date appraisal of the pathophysiology, clinical features, and management approaches for PI-IBS.

RECENT FINDINGS

Disordered immune reactions and release of cytokines with resultant gut inflammation and dysfunction appear to be key features of PI-IBS. Disordered brain-gut-microbiota interactions, type of infecting agent, and host-genetic susceptibility are risk factors but also are reasons for the varying spectrum of clinical severity. Although prognosis is generally good, symptoms and inflammation may persist for a long time. Symptomatic relief with antidiarrheals, antispasmodics, 5HT₃ antagonists, mesalamine, probiotics, and low-dose antidepressants remain the primary approaches, but in some difficult cases, a combination of drugs that target the pathophysiology may be helpful. PI-IBS has many overlapping features with IBS-D and shares similar pathophysiology and management approaches.

Cysteine Protease-Dependent Mucous Disruptions and Differential Mucin Gene Expression in Giardia duodenalis Infection

The intestinal mucous layer provides a critical host defense against pathogen exposure and epithelial injury, yet little is known about how enteropathogens may circumvent this physiologic barrier. Giardia duodenalis is a small intestinal parasite responsible for diarrheal disease and chronic postinfectious illness. This study reveals a complex interaction at the surface of epithelial cells, between G. duodenalis and the intestinal mucous layer. Here, we reveal mechanisms whereby G. duodenalis evades and disrupts the first line of host defense by degrading human mucin-2 (MUC2), depleting mucin stores and inducing differential gene expression in the mouse small and large intestines. Human colonic biopsy specimens exposed to G. duodenalis were depleted of mucus, and in vivo mice infected with G. duodenalis had a thinner mucous layer and demonstrated differential Muc2 and Muc5ac mucin gene expression. Infection in Muc2^-/- mice elevated trophozoite colonization in the small intestine and impaired weight gain. In vitro, human LS174T goblet-like cells were depleted of mucus and had elevated levels of MUC2 mRNA expression after G. duodenalis exposure. Importantly, the cysteine protease inhibitor E64 prevented mucous degradation, mucin depletion, and the increase in MUC2 expression. This article describes a novel role for Giardia's cysteine proteases in pathogenesis and how Giardia's disruptions of the mucous barrier facilitate bacterial translocation that may contribute to the onset and propagation of disease.

Experience and Outcomes at a Specialized Clostridium difficile Clinical Practice

Objective

To report our experience with and outcomes among patients referred to a specialized Clostridium difficile clinical practice.

Patients and Methods

We retrospectively identified consecutive patients referred for Clostridium difficile infection (CDI) management from January 1, 2013, through May 30, 2015. Data were collected for demographic characteristics, CDI history, final diagnoses, and management.

Results

Overall, 211 patients (median age, 65 years; 66.4% women) were included. The most common indications for referral were recurrent CDI in 199 patients (94.3%), first CDI episode in 5 patients (2.4%), and chronic diarrhea in 7 patients (3.3%). After evaluation, the diagnoses were recurrent CDI in 127 patients (60.2%), resolved CDI in 36 patients (17.1%), first-episode CDI in 5 patients (2.4%), and non-CDI in 43 patients (20.4%). The most common non-CDI diagnoses were postinfection irritable bowel syndrome (PI-IBS) in 32 patients (15.2% overall), inflammatory bowel disease (n=3), small intestinal bacterial overgrowth (n=2), microscopic colitis (n=1), and asymptomatic C difficile colonization (n=2). Two patients had diabetic gastroparesis and food intolerances, and 1 had chronic constipation with overflow diarrhea. Of 127 patients with recurrent CDI, 30 (23.6%) received antibiotics; of these 30, 12 had antibiotic treatment failure and received fecal microbiota transplantation (FMT) for recurrent CDI. Among 97 patients (76.4%) who underwent FMT, 85 (87.6%) were cured after the first FMT, 5 were cured after the second FMT, and 7 were treated with antibiotics for FMT failure, with resolution of symptoms.

Conclusion

A substantial proportion of patients referred for CDI subsequently received alternative diagnoses; PI-IBS was the most common. Patients being referred for recurrent CDI should be evaluated carefully for alternative diagnoses.

A High Rate of Alternative Diagnoses in Patients Referred for Presumed Clostridium difficile Infection

GOALS

We evaluated a cohort of patients referred to our center for presumed recurrent Clostridium difficile infection (CDI) to determine final diagnoses and outcomes.

BACKGROUND

As rates of CDI have increased, more patients are diagnosed with recurrent CDI and other sequelae of the infection. Distinguishing symptomatic patients with CDI from those who are colonized with an alternative etiology of diarrheal symptoms may be challenging.

MATERIALS AND METHODS

We performed a retrospective review of 117 patients referred to our center for recurrent CDI between January 2013 and June 2014. Data collected included demographics, the referring provider, previous anti-CDI treatment, and significant medical conditions. In addition, we gathered data on atypical features of CDI and investigations obtained to investigate the etiology of symptoms. Outcomes included rates of alternative diagnoses and the accuracy of CDI diagnosis by the referral source.

RESULTS

The mean age was 61 years, and 70% were female. About 29 patients (25%) were determined to have a non-CDI diagnosis. Most common alternative diagnoses included irritable bowel syndrome (18 patients: 62%) and inflammatory bowel disease (3 patients:10%). The age was inversely correlated with the rate of non-CDI diagnosis (P=0.016). Of the remaining 88 (75%) patients with a confirmed diagnosis of CDI, 25 (28%) received medical therapy alone and 63 (72%) underwent fecal microbiota transplantation.

CONCLUSIONS

Among patients referred to our center for recurrent CDI, a considerable percentage did not have CDI, but rather an alternative diagnosis, most commonly irritable bowel syndrome. The rate of alternative diagnosis correlated inversely with age. Providers should consider other etiologies of diarrhea in patients presenting with features atypical of recurrent CDI.

Gut-derived cholecystokinin contributes to visceral hypersensitivity via nerve growth factor-dependent neurite outgrowth

BACKGROUND AND AIM

Irritable bowel syndrome is characterized by abdominal pain and altered bowel habits and may occur following stressful events or infectious gastroenteritis such as giardiasis. Recent findings revealed a link between cholecystokinin (CCK), neurotrophin synthesis, and intestinal hyperalgesia. The aim was to investigate the role of CCK in visceral hypersensitivity using mouse models challenged with a bout of infection with Giardia lamblia or psychological stress, either alone or in combination.

METHODS

Abdominal pain was evaluated by visceromoter response to colorectal distension. Nerve fibers in intestinal tissues were stained using immunohistochemistry (PGP9.5). Human neuroblastoma SH-SY5Y cells incubated with bacterial-free mouse gut supernatant or recombinant CCK-8S were assessed for neurite outgrowth and nerve growth factor (NGF) production.

RESULTS

Intestinal hypersensitivity was induced by either stress or Giardia infection, and a trend of increased pain was seen following dual stimuli. Increased CCK levels and PGP9.5 immunoreactivity were found in colonic mucosa of mice following stress and/or infection. Inhibitors to the CCK-A receptor (L-364718) or CCK-B receptor (L-365260) blocked visceral hypersensitivity caused by stress, but not when induced by giardiasis. Nerve fiber elongation and NGF synthesis were observed in SH-SY5Y cells after incubation with colonic supernatants from mice given the dual stimuli, or after treatment with CCK-8S. Increased nerve fiber length by colonic supernatant and CCK-8S was attenuated by L-365260 or neutralizing anti-NGF.

CONCLUSIONS

This new model successfully recapitulates intestinal hypernociception induced by stress or Giardia. Colonic CCK contributes to visceral hypersensitivity caused by stress, but not by Giardia, partly via NGF-dependent neurite outgrowth.

Giardia lamblia infection increases risk of chronic gastrointestinal disorders

BACKGROUND

Giardia lamblia is a common parasitic cause of infectious gastroenteritis in the United States and the world and may be linked to an increased risk of chronic gastrointestinal (GI) disorders. We sought to assess the risk of several chronic GI disorders following Giardia infection among active duty US military personnel.

METHODS

This study was designed as a retrospective cohort study in which active duty military personnel with documented G. lamblia infection were assessed for the subsequent risk of developing a chronic GI disorder including irritable bowel syndrome (IBS), dyspepsia and gastroesophageal reflux disease (GERD). Post-giardia chronic GI disorder risk was compared to risk in uninfected personnel matched on several demographic characteristics and medical encounter information. Data were obtained from the Defense Medical Surveillance System and exposures (1998-2009) with outcomes identified based on documented medical encounters with specific medical billing codes. Modified Poisson regression was used to evaluate the relationship between G. lamblia infection and chronic GI disorders.

RESULTS

A total of 80 Giardia cases were identified for an estimated incidence of 0.55 cases per 100,000 person-years. Cases were matched to 294 unexposed subjects. After adjusting for important covariates, there was an increased risk of IBS (relative risk: 2.1, p = 0.03) associated with antecedent Giardia infection.

CONCLUSION

These data add to a growing body of literature and demonstrate an increased risk of IBS after infection with G. lamblia.

Current status of Blastocystis: A personal view

Despite Blastocystis being one of the most widespread and prevalent intestinal eukaryotes, its role in health and disease remains elusive. DNA-based detection methods have led to a recognition that the organism is much more common than previously thought, at least in some geographic regions and some groups of individuals. Molecular methods have also enabled us to start categorizing the vast genetic heterogeneity that exists among Blastocystis isolates, wherein the key to potential differences in the clinical outcome of Blastocystis carriage may lie. In this review we summarize some of the recent developments and advances in Blastocystis research, including updates on diagnostic methods, molecular epidemiology, genetic diversity, host specificity, clinical significance, taxonomy, and genomics. As we are now in the microbiome era, we also review some of the steps taken towards understanding the place of Blastocystis in the intestinal microbiota.

Pathogenic role of the gut microbiota in gastrointestinal diseases

The gastrointestinal (GI) tract is colonized by a dense community of commensal microorganisms referred to as the gut microbiota. The gut microbiota and the host have co-evolved, and they engage in a myriad of immunogenic and metabolic interactions. The gut microbiota contributes to the maintenance of host health. However, when healthy microbial structure is perturbed, a condition termed dysbiosis, the altered gut microbiota can trigger the development of various GI diseases including inflammatory bowel disease, colon cancer, celiac disease, and irritable bowel syndrome. There is a growing body of evidence suggesting that multiple intrinsic and extrinsic factors, such as genetic variations, diet, stress, and medication, can dramatically affect the balance of the gut microbiota. Therefore, these factors regulate the development and progression of GI diseases by inducing dysbiosis. Herein, we will review the recent advances in the field, focusing on the mechanisms through which intrinsic and extrinsic factors induce dysbiosis and the role a dysbiotic microbiota plays in the pathogenesis of GI diseases.

Giardia duodenalis induces paracellular bacterial translocation and causes postinfectious visceral hypersensitivity

Irritable bowel syndrome (IBS) is the most frequent functional gastrointestinal disorder. It is characterized by abdominal hypersensitivity, leading to discomfort and pain, as well as altered bowel habits. While it is common for IBS to develop following the resolution of infectious gastroenteritis [then termed postinfectious IBS (PI-IBS)], the mechanisms remain incompletely understood. Giardia duodenalis is a cosmopolitan water-borne enteropathogen that causes intestinal malabsorption, diarrhea, and postinfectious complications. Cause-and-effect studies using a human enteropathogen to help investigate the mechanisms of PI-IBS are sorely lacking. In an attempt to establish causality between giardiasis and postinfectious visceral hypersensitivity, this study describes a new model of PI-IBS in neonatal rats infected with G. duodenalis At 50 days postinfection with G. duodenalis (assemblage A or B), long after the parasite was cleared, rats developed visceral hypersensitivity to luminal balloon distension in the jejunum and rectum, activation of the nociceptive signaling pathway (increased c-fos expression), histological modifications (villus atrophy and crypt hyperplasia), and proliferation of mucosal intraepithelial lymphocytes and mast cells in the jejunum, but not in the rectum. G. duodenalis infection also disrupted the intestinal barrier, in vivo and in vitro, which in turn promoted the translocation of commensal bacteria. Giardia-induced bacterial paracellular translocation in vitro correlated with degradation of the tight junction proteins occludin and claudin-4. The extensive observations associated with gut hypersensitivity described here demonstrate that, indeed, in this new model of postgiardiasis IBS, alterations to the gut mucosa and c-fos are consistent with those associated with PI-IBS and, hence, offer avenues for new mechanistic research in the field.

Nutritional advice for community patients: insights from a panel discussion

This article describes the conclusions of an expert panel that discussed four case studies; these were examples of patients typically encountered by nurses working in the community. The panel considered the nutritional and lifestyle advice that could be given by nurses relating to conditions such as irritable bowel syndrome (IBS), depression, chronic fatigue syndrome, vulnerability to common infections, elderly care, recurrent urinary tract infection, antibiotic use, and risk of type 2 diabetes. A general conclusion was the importance of motivational interviewing techniques in achieving full understanding of patients' concerns and to determine the best health strategy. As well as specific guidance appropriate for each disorder, a range of information sources for both health professionals and patients are listed in the paper. The panel noted that, although general nutritional advice can be given by nurses working at GP surgeries and in the community, patients should always be referred to registered dietitians or nutritionists if significant dietary changes are considered.

Synergistic Effect and Molecular Mechanisms of Traditional Chinese Medicine on Regulating Tumor Microenvironment and Cancer Cells

The interaction of tumor cells with the microenvironment is like a relationship between the “seeds” and “soil,” which is a hotspot in recent cancer research. Targeting at tumor microenvironment as well as tumor cells has become a new strategy for cancer treatment. Conventional cancer treatments mostly focused on single targets or single mechanism (the seeds or part of the soil); few researches intervened in the whole tumor microenvironment and achieved ideal therapeutic effect as expected. Traditional Chinese medicine displays a broad range of biological effects, and increasing evidence has shown that it may relate with synergistic effect on regulating tumor microenvironment and cancer cells. Based on literature review and our previous studies, we summarize the synergistic effect and the molecular mechanisms of traditional Chinese medicine on regulating tumor microenvironment and cancer cells.

Overlapping irritable bowel syndrome and inflammatory bowel disease: less to this than meets the eye?

Though distinct in terms of pathology, natural history and therapeutic approach, irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD) have some features in common. These include shared symptomatology and largely similar demographics. However, in most instances, clinical presentation, together with laboratory, imaging and endoscopic findings will readily permit the differentiation of active IBD from IBS. More problematic is the situation where a subject with IBD, in apparent remission, continues to complain of symptoms which, in aggregate, satisfy commonly employed criteria for the diagnosis of IBS. Access to methodologies, such the assay for levels of calprotectin in feces, now allows identification of ongoing inflammation in some such individuals and prompts appropriate therapy. More challenging is the IBD patient with persisting symptoms and no detectable evidence of inflammation; is this coincident IBS, IBS triggered by IBD or an even more subtle level of IBD activity unrecognized by available laboratory or imaging methods? Arguments can be advanced for each of these proposals; lacking definitive data, this issue remains unresolved. The occurrence of IBS-type symptoms in the IBD patient, together with some data suggesting a very subtle level of 'inflammation' or 'immune activation' in IBS, raises other questions: is IBS a prodromal form of IBD; and are IBS and IBD part of the spectrum of the same disease? All of the available evidence indicates that the answer to both these questions should be a resounding 'no'. Indeed, the whole issue of overlap between IBS and IBD should be declared moot given their differing pathophysiologies, contrasting natural histories and divergent treatment paths. The limited symptom repertoire of the gastrointestinal tract may well be fundamental to the apparent confusion that has, of late, bedeviled this area.

Inflammation in irritable bowel syndrome: Myth or new treatment target?

Low-grade intestinal inflammation plays a key role in the pathophysiology of irritable bowel syndrome (IBS), and this role is likely to be multifactorial. The aim of this review was to summarize the evidence on the spectrum of mucosal inflammation in IBS, highlighting the relationship of this inflammation to the pathophysiology of IBS and its connection to clinical practice. We carried out a bibliographic search in Medline and the Cochrane Library for the period of January 1966 to December 2014, focusing on publications describing an interaction between inflammation and IBS. Several evidences demonstrate microscopic and molecular abnormalities in IBS patients. Understanding the mechanisms underlying low-grade inflammation in IBS may help to design clinical trials to test the efficacy and safety of drugs that target this pathophysiologic mechanism.

Graded effects of unregulated smooth muscle myosin on intestinal architecture, intestinal motility and vascular function in zebrafish

Smooth muscle contraction is controlled by the regulated activity of the myosin heavy chain ATPase (Myh11). Myh11 mutations have diverse effects in the cardiovascular, digestive and genitourinary systems in humans and animal models. We previously reported a recessive missense mutation, meltdown (mlt), which converts a highly conserved tryptophan to arginine (W512R) in the rigid relay loop of zebrafish Myh11. The mlt mutation disrupts myosin regulation and non-autonomously induces invasive expansion of the intestinal epithelium. Here, we report two newly identified missense mutations in the switch-1 (S237Y) and coil-coiled (L1287M) domains of Myh11 that fail to complement mlt Cell invasion was not detected in either homozygous mutant but could be induced by oxidative stress and activation of oncogenic signaling pathways. The smooth muscle defect imparted by the mlt and S237Y mutations also delayed intestinal transit, and altered vascular function, as measured by blood flow in the dorsal aorta. The cell-invasion phenotype induced by the three myh11 mutants correlated with the degree of myosin deregulation. These findings suggest that the vertebrate intestinal epithelium is tuned to the physical state of the surrounding stroma, which, in turn, governs its response to physiologic and pathologic stimuli. Genetic variants that alter the regulation of smooth muscle myosin might be risk factors for diseases affecting the intestine, vasculature, and other tissues that contain smooth muscle or contractile cells that express smooth muscle proteins, particularly in the setting of redox stress.