Postinfectious Chronic Gut Dysfunction: From Bench to Bedside

Functional dyspepsia in children: A study of pathophysiological factors

BACKGROUND AND AIM

Functional dyspepsia (FD) is common in children, and treatment targeted towards the altered pathophysiology can improve outcome. We evaluated FD children for abnormality of gastric accommodation and emptying, psychological stressors (PS), Helicobacter pylori (HP) infection, and post-infectious FD.

METHODS

Diagnosis of FD was based on ROME III criteria. Clinical evaluation including dyspeptic symptom scoring and assessment for PS was performed. Satiety drink test for gastric accommodation, gastroscopy with biopsy for HP infection, and solid meal gastric emptying were performed. Sixty-seven healthy children were enrolled for assessing PS and satiety drink test.

RESULTS

Fifty-five FD children (33 boys, age 12 [6-18] years) with symptoms for 4 (2-48) months and dyspeptic score of 5 (1-13) were enrolled. PS were more common in FD than in controls (46/55 vs 9/67; P < 0.001). Median satiety drink volume was 360 mL (180-1320 mL); no patients had satiety drink volume of < 5th centile of healthy children. The frequency (98% vs 85%; P = 0.01) and severity (65 [10-175] vs 50 [5-130]; P < 0.001) of postprandial symptoms were higher in FD than in controls. Of the postprandial symptoms, pain (20.3% vs 0%; P = 0.000) was present only in FD. Delayed gastric emptying was present in 6.5%, HP infection in 11%, and post-infectious FD in 13% cases. Etiological factor was identified in 87% children, with 20% having multiple factors.

CONCLUSIONS

Abnormality of gastric sensorimotor function is seen in one-fourth of FD cases. HP infection and post-infectious FD are present in 11% and 13% cases, respectively.

Irritable Bowel Syndrome and Neurological Deficiencies: Is There A Relationship? The Possible Relevance of the Oxidative Stress Status

Background: Irritable bowel syndrome (IBS) is one of the most common functional gastrointestinal disorders, exhibiting complex and controversial pathological features. Both oxidative stress and inflammation-related reactive oxygen species production may be involved in IBS pathological development. Thus, we focused on several aspects regarding the causes of oxidative stress occurrence in IBS. Additionally, in the molecular context of oxidative changes, we tried to discuss these possible neurological implications in IBS. Methods: The literature search included the main available databases (e.g., ScienceDirect, Pubmed/Medline, Embase, and Google Scholar). Articles in the English language were taken into consideration. Our screening was conducted based on several words such as “irritable bowel syndrome”, “gut brain axis”, “oxidative stress”, “neuroendocrine”, and combinations. Results: While no consistent evidence suggests clear pathway mechanisms, it seems that the inflammatory response may also be relevant in IBS. The mild implication of oxidative stress in IBS has been described through clinical studies and some animal models, revealing changes in the main markers such as antioxidant status and peroxidation markers. Moreover, it seems that the neurological structures involved in the brain-gut axis may be affected in IBS rather than the local gut tissue and functionality. Due to a gut-brain axis bidirectional communication error, a correlation between neurological impairment, emotional over-responsiveness, mild inflammatory patterns, and oxidative stress can be suggested. Conclusions: Therefore, there is a possible correlation between neurological impairment, emotional over-responsiveness, mild inflammatory patterns, and oxidative stress that are not followed by tissue destruction in IBS patients. Moreover, it is not yet clear whether oxidative stress, inflammation, or neurological impairments are key determinants or in which way these three interact in IBS pathology. However, the conditions in which oxidative imbalances occur may be an interesting research lead in order to find possible explanations for IBS development.

Incidence of irritable bowel syndrome and chronic fatigue following GI infection: a population-level study using routinely collected claims data

OBJECTIVES

To investigate the occurrence of postinfectious IBS in routine outpatient care, comparing different types of GI infection and its interaction with psychosomatic comorbidity.

DESIGN

Retrospective cohort study using routinely collected claims data covering statutorily insured patients in Bavaria, Germany. Cases were defined as patients without prior record of functional intestinal disorder with a first-time diagnosis of GI infection between January 2005 and December 2013 and classed according to the type of infection. Each case was matched by age, sex and district of residence to a patient without history of GI infection. Prior psychological disorder (depression, anxiety or stress reaction disorder) was assessed in the 2 years prior to inclusion. Proportional hazards regression models were used to estimate the HRs for GI infection and psychological disorder. Chronic fatigue syndrome (CFS) was assessed as a comparator outcome.

RESULTS

A total of 508 278 patients with first diagnosis of GI infection were identified, resulting in a matched cohort of 1 016 556 patients. All infection types were associated with an increased risk of IBS (HR: 2.19-4.25) and CFS (HR 1.35-1.82). Prior psychological disorder was a distinct risk factor for IBS (HR: 1.73) and CFS (HR: 2.08). Female sex was a further risk factor for both conditions.

CONCLUSION

Psychological disorder and GI infections are distinct risk factors for IBS. The high incidence of non-specific GI infection suggests that postinfectious IBS is a common clinical occurrence in primary care. Chronic fatigue is a further significant sequela of GI infection.

Intestinal lymphatic vasculature: structure, mechanisms and functions

The mammalian intestine is richly supplied with lymphatic vasculature, which has functions ranging from maintenance of interstitial fluid balance to transport of antigens, antigen-presenting cells, dietary lipids and fat-soluble vitamins. In this Review, we provide in-depth information concerning the organization and structure of intestinal lymphatics, the current view of their developmental origins, as well as molecular mechanisms of intestinal lymphatic patterning and maintenance. We will also discuss physiological aspects of intestinal lymph flow regulation and the known and emerging roles of intestinal lymphatic vessels in human diseases, such as IBD, infection and cancer.

Role of Serum Amyloid A, Granulocyte-Macrophage Colony-Stimulating Factor, and Bone Marrow Granulocyte-Monocyte Precursor Expansion in Segmented Filamentous Bacterium-Mediated Protection from Entamoeba histolytica

Intestinal segmented filamentous bacteria (SFB) protect from ameba infection, and protection is transferable with bone marrow dendritic cells (BMDCs). SFB cause an increase in serum amyloid A (SAA), suggesting that SAA might mediate SFB's effects on BMDCs. Here we further explored the role of bone marrow in SFB-mediated protection. Transient gut colonization with SFB or SAA administration alone transiently increased the H3K27 histone demethylase Jmjd3, persistently increased bone marrow Csf2ra expression and granulocyte monocyte precursors (GMPs), and protected from ameba infection. Pharmacologic inhibition of Jmjd3 H3K27 demethylase activity during SAA treatment or blockade of granulocyte-macrophage colony-stimulating factor (GM-CSF) signaling in SFB-colonized mice prevented GMP expansion, decreased gut neutrophils, and blocked protection from ameba infection. These results indicate that alteration of the microbiota and systemic exposure to SAA can influence myelopoiesis and susceptibility to amebiasis via epigenetic mechanisms. Gut microbiota-marrow communication is a previously unrecognized mechanism of innate protection from infection.

Functional Gastrointestinal Disorders: History, Pathophysiology, Clinical Features and Rome IV

Functional gastrointestinal disorders (FGIDs), the most common diagnoses in gastroenterology are recognized by morphological and physiological abnormalities that often occur in combination including motility disturbance, visceral hypersensitivity, altered mucosal and immune function, altered gut microbiota and altered central nervous system processing. Research on these gut-brain interaction disorders is based on using specific diagnostic criteria. The Rome Foundation has played a pivotal role in creating diagnostic criteria thus operationalizing the dissemination of new knowledge in the field of FGIDs. Rome IV is a compendium of the knowledge accumulated since Rome III was published 10 years ago. It improves upon Rome III by: 1) updating the basic and clinical literature, 2) offering new information on gut microenvironment, gut-brain interactions, pharmacogenomics, biopsychosocial, gender and cross cultural understandings of FGIDs, 3) reduces the use of imprecise and occassionally stigmatizing terms when possible, 4) uses updated diagnostic algorithms, 5) incorporates information on the patient illness experience, and physiological subgroups or biomarkers that might lead to more targeted treatment. This introductory article sets the stage for the remaining 17 articles that follow and offers an historical overview of the FGIDs field, differentiates FGIDs from motility and structural disorders, discusses the changes from Rome III, reviews the Rome committee process, provides a biopsychosocial pathophysiological conceptualization of FGIDs, and offers an approach to patient care.

Miniature Swine for Preclinical Modeling of Complexities of Human Disease for Translational Scientific Discovery and Accelerated Development of Therapies and Medical Devices

Noncommunicable diseases, including cardiovascular disease, diabetes, chronic respiratory disease, and cancer, are the leading cause of death in the world. The cost, both monetary and time, of developing therapies to prevent, treat, or manage these diseases has become unsustainable. A contributing factor is inefficient and ineffective preclinical research, in which the animal models utilized do not replicate the complex physiology that influences disease. An ideal preclinical animal model is one that responds similarly to intrinsic and extrinsic influences, providing high translatability and concordance of preclinical findings to humans. The overwhelming genetic, anatomical, physiological, and pathophysiological similarities to humans make miniature swine an ideal model for preclinical studies of human disease. Additionally, recent development of precision gene-editing tools for creation of novel genetic swine models allows the modeling of highly complex pathophysiology and comorbidities. As such, the utilization of swine models in early research allows for the evaluation of novel drug and technology efficacy while encouraging redesign and refinement before committing to clinical testing. This review highlights the appropriateness of the miniature swine for modeling complex physiologic systems, presenting it as a highly translational preclinical platform to validate efficacy and safety of therapies and devices.

The long-term functional consequences of acute infectious diarrhea

PURPOSE OF REVIEW

The study reviews recent publications that build on previous studies showing that acute enteric infection can produce persistent dysfunction in the lower gut (postinfectious irritable bowel syndrome) and proximal gut (postinfectious functional dyspepsia). The review addresses risk factors, the pathophysiological basis of persistent gut dysfunction, and the factors that initiate and maintain it.

RECENT FINDINGS

Recent work has identified several loci of host genetic predisposition to these syndromes that focus attention on host immune responses that may lead to gut dysfunction, including changes in intestinal barrier function and cytokine responses to the initial infection. Human and animal studies identify changes in the serotonergic and cannabinoid pathways regulating visceral pain responses and gut motility. Recent work has also focused attention on the putative role of the intestinal microbiota or dysbiosis in maintaining gut dysfunction and this is reviewed in depth.

SUMMARY

The development of long-term consequences following an acute episode of gastroenteritis reflects a convergence of host factors that include genetic predisposition and psychological factors, as well as the development of intestinal dysbiosis. It is anticipated that future research will generate biomarkers of susceptibility as well as novel microbiota-directed preventive and therapeutic strategies.

Human microbiome: From the bathroom to the bedside

The human gut contains trillions of bacteria, the major phylae of which include Bacteroidetes, Firmicutes, Actinobacteria and Proteobacteria. Fecal microbial transplantation (FMT) has been known of for many years but only recently has been subjected to rigorous examination. We review the evidence regarding FMT for recurrent Clostridium difficile infection which has resulted in it being an approved treatment. In addition there is some evidence for its use in both irritable bowel syndrome and inflammatory bowel disease. Further research is needed in order to define the indications for FMT and the most appropriate method of administration.

Systematic review with meta-analysis: post-infectious functional dyspepsia

BACKGROUND

The prevalence of functional dyspepsia (FD) following infectious gastroenteritis has not been systematically reviewed.

AIM

To conduct a systematic review and calculate the summary odds ratio (OR) for the development of FD following infectious gastroenteritis, as compared to a control population.

METHODS

Published studies in PubMed, EmBASE, and Cochrane Database and abstracts from standard sources were screened for eligible studies. Data from studies meeting inclusion criteria were pooled for meta-analysis.

RESULTS

Nineteen studies were eligible for inclusion. The mean prevalence of FD following acute gastroenteritis (AGE) was 9.55% (FD, n = 909; AGE, n = 9517) in adult populations. The summary OR for the development of post-infectious FD was 2.54 (95% CI = 1.76-3.65) at more than 6 months after AGE, as compared to the prevalence in controls within the same population. This is compared with the summary OR (3.51; 95% CI = 2.05-6.00) for the development of post-infectious irritable bowel syndrome (IBS) in the same population at more than 6 months after AGE. There was significant statistical heterogeneity with an I(2) of 72.8% for the summary OR of post-infectious FD. Several pathogens, including Salmonella spp., Escherichia coli O157, Campylobacter jejuni, Giardia lamblia and Norovirus have been shown to be associated with post-infectious FD symptoms.

CONCLUSIONS

Infectious gastroenteritis is associated with an increased risk for subsequent dyspepsia as well as for irritable bowel syndrome. Post-infectious FD and post-infectious irritable bowel syndrome may represent different aspects of the same pathophysiology. Further studies will be needed to determine this.

Probiotic Lactobacillus rhamnosus GG (LGG) and prebiotic prevent neonatal inflammation-induced visceral hypersensitivity in adult rats

BACKGROUND

Increasing evidence indicates a positive effect of probiotics on the nervous system. The objective of this study was to determine if probiotic Lactobacillus rhamnosus GG (LGG) and/or prebiotics polydextrose/galactooligosaccharide (PDX/GOS) can alter the colonic sensitivity in a neonatal rat model of chronic visceral hyperalgesia and to determine whether altered sensitivity is associated with changes in neurotransmitter levels in the brain.

METHODS

Chronic visceral hyperalgesia was induced in rats by intracolonic administration of zymosan for 3 days during postnatal day 14-16 (P14-P16). After weaning (P21), these pups were divided into groups that received either (1) control diet (CD), (2) PDX/GOS, (3) LGG, or (4) PDX/GOS + LGG. These diets were continued until visceral sensitivity was tested at P60. The viscero-motor response (VMR) to graded colorectal distension (CRD) was determined by measuring the electromyographic (EMG) activity from the abdominal external oblique muscles. The levels of neurotransmitters and biogenic amines were quantified in the frontal cortex, subcortex, brain stem, and cerebellum.

KEY RESULTS

At P60, the VMR to CRD in the neonatal zymosan-treated rats was significantly higher than neonatal saline-treated rats. In contrast, neonatal zymosan-treated rats that received PDX/GOS or LGG did not exhibit visceral hyperalgesia. The levels of serotonin, noradrenaline, and dopamine were significantly altered in LGG-treated rats compared to other groups.

CONCLUSIONS & INFERENCES

Results document that in rats LGG can attenuate neonatally induced chronic visceral pain measured in adulthood. Prolonged intake of LGG alters some key brain neurotransmitters and biogenic amines that could be involved in pain modulation.

Therapeutic faecal microbiota transplantation: current status and future developments

PURPOSE OF REVIEW

Faecal microbiota transplantation (FMT) has undergone dramatic progression over the past year and continues to evolve as knowledge of the gastrointestinal microbiota (GiMb) develops. This review summarizes therapeutic advances in FMT, latest FMT therapies and presents the potential of FMT therapeutics in other gastrointestinal and extra-intestinal conditions.

RECENT FINDINGS

The GiMb is now known to have a central role in the pathogenesis of many diseases. The success of FMT in curing Clostridium difficile infection (CDI) is well established and preliminary findings in other gastrointestinal conditions are promising. Published data from over 500 CDI cases suggest that FMT is generally well tolerated with minimal side effects. The commercial potential of FMT is being explored with several products under development, including frozen GiMb extract, which has been shown highly effective in treating relapsing CDI. Such products will likely become more available in coming years and revolutionize the availability and method of delivery of GiMb.

SUMMARY

Recent literature unequivocally supports the use of FMT in treating relapsing CDI. Trials are underway to determine the therapeutic potential of FMT in other conditions, particularly inflammatory bowel disease. Therapeutic FMT is a dynamic field with new and emerging indications along with ongoing developments in optimal mode of administration.

[Irritable bowel syndrome, celiac disease and gluten]

For many years irritable bowel syndrome (IBS) and celiac disease (CD) have been considered 2 completely separate entities, with CD being clearly related to a permanent gluten intolerance and IBS having no relation with gluten ingestion. However IBS and CD symptoms may be indistinguishable, especially when diarrhea, bloating or abdominal pain predominate. In the last decade several studies have shown that the separation between CD and IBS is not so clear. Thus, some patients who have been diagnosed of IBS suffer in fact from CD. In addition, it seems that there is a group of patients who, without having CD, suffer gluten intolerance that cause them digestive symptoms similar to those of IBS. Gluten sensitivity is defined as the spectrum of morphological, immunological and functional abnormalities that respond to a gluten-free diet. This concept includes histological, immunological and clinical manifestations in the absence of evident morphological abnormalities. Therefore, it is mandatory to establish in a scientific way in which patients a gluten-free diet will be beneficial as well as when this is not justified.

Fecal microbiota transplantation: past, present and future

PURPOSE OF REVIEW

Fecal microbiota transplantation (FMT) re-establishes a balanced intestinal flora with resultant cure of recurrent Clostridium difficile infection (RCDI). FMT has also been used to treat other gastrointestinal (GI) diseases including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and chronic constipation and a variety of non-GI disorders. The purpose of this review is to discuss the intestinal microbiota and FMT treatment of GI and non-GI diseases.

RECENT FINDINGS

It is known that an imbalanced intestinal microbiota predisposes to CDI, IBD and IBS. The complex role of intestinal microbiota to maintain health, however, is a newer concept that is being increasingly studied. The microbiome plays an important role in cellular immunity and energy metabolism and has been implicated in the pathogenesis of non-GI autoimmune diseases, chronic fatigue syndrome, obesity and even some neuropsychiatric disorders.

SUMMARY

FMT is a highly effective cure for RCDI, but increased knowledge of the intestinal microbiota in health maintenance, as well as controlled trials of FMT in a wide range of disorders are needed before FMT can be accepted and applied clinically.