Altered gut microbiota in patients with small intestinal bacterial overgrowth

BACKGROUND AND AIM

Small intestinal bacterial overgrowth (SIBO) is diagnosed by using quantitative culture of duodenal aspirates and/or a hydrogen breath test. However, few studies have analyzed bacterial microbiota in Japanese patients with SIBO.

METHODS

Twenty-four patients with any abdominal symptoms and suspected SIBO were enrolled. Quantitative culture of duodenal aspirates and a glucose hydrogen breath test were performed on the same day. SIBO was diagnosed based on a bacterial count ≥ 10³  CFU/mL or a rise in the hydrogen breath level of ≥ 20 ppm. The composition of the duodenal microbiota was analyzed by 16S rRNA gene sequencing.

RESULTS

Small intestinal bacterial overgrowth was diagnosed in 17 of the 24 patients (71%). The positive rates for the hydrogen breath test and quantitative culture of duodenal aspirates were 50% and 62%, respectively. Patients with SIBO showed significantly reduced α-diversity compared with non-SIBO patients, and analysis of β-diversity revealed significantly different distributions between SIBO and non-SIBO patients. In addition, the intestinal microbiome in SIBO patients was characterized by increased relative abundance of Streptococcus and decreased relative abundance of Bacteroides compared with non-SIBO patients.

CONCLUSIONS

Duodenal dysbiosis was identified in patients with SIBO and may play a role in the pathophysiology of SIBO.

The Anti-Inflammatory Properties of Licorice (Glycyrrhiza glabra)-Derived Compounds in Intestinal Disorders

Intestinal diseases, such as inflammatory bowel diseases (IBDs) and colorectal cancer (CRC), are a significant source of morbidity and mortality worldwide. Epidemiological data have shown that IBD patients are at an increased risk for the development of CRC. IBD-associated cancer develops against a background of chronic inflammation and oxidative stress, and their products contribute to cancer development and progression. Therefore, the discovery of novel drugs for the treatment of intestinal diseases is urgently needed. Licorice (Glycyrrhiza glabra) has been largely used for thousands of years in traditional Chinese medicine. Licorice and its derived compounds possess antiallergic, antibacterial, antiviral, anti-inflammatory, and antitumor effects. These pharmacological properties aid in the treatment of inflammatory diseases. In this review, we discuss the pharmacological potential of bioactive compounds derived from Licorice and addresses their anti-inflammatory and antioxidant properties. We also discuss how the mechanisms of action in these compounds can influence their effectiveness and lead to therapeutic effects on intestinal disorders.

Overview of the Large Bowel Assessment Using Magnetic Resonance Imaging: Different Techniques for Current and Emerging Clinical Applications

Radiological assessments of the small and large bowel are essential in daily clinical practice. Over plain film X-ray and ultrasound, cross-sectional techniques are considered the most comprehensive imaging modalities. In fact, computed tomography and magnetic resonance imaging take great advantage of the three-dimensional appraisal and the extensive evaluation of the abdominal cavity, allowing intestinal evaluation as well as detection of extra-intestinal findings. In this context, the chief advantage of computed tomography is the fast scan time, which is crucial for emergency cases. Nonetheless, it is undeniably impaired using ionizing radiation. As the awareness of radiation exposure is a topic of increasing importance, magnetic resonance imaging is not only becoming a mere alternative but also a primary imaging technique used in assessing intestinal diseases. Specifically, the evaluation of the large bowel through MRI can be still considered relatively uncharted territory. Although it has demonstrated superior accuracy in the assessment of some clinical entities from inflammatory bowel disease to rectal carcinoma, its role needs to be consolidated in many other conditions. Moreover, different technical methods can be applied for colonic evaluation depending on the specific disease and segment involved. This article aims to provide a thorough overview of the techniques that can be utilized in the evaluation of the large bowel and a discussion on the major findings in different colonic pathologies of primary interest.

Human Leukocyte Antigen DQ (HLA-DQ) genotypes and haplotypes and their association with phenotype in patients with celiac disease in India

Background and Aim

Human Leukocyte Antigen DQ (HLA‐DQ) genotypes play a permissive role in the genesis of celiac disease (CeD). In this case–control study, we used next‐generation sequencing to determine HLA‐DQA1 and ~DQB1 genotypes and haplotypes associated with CeD in Indian patients.

Methods

HLA‐DQA1 and ~DQB1 loci were amplified, using long‐range polymerase chain reaction (PCR), from DNA of 259 patients with symptomatic CeD (160 typical and 99 atypical), 45 asymptomatic CeD, 96 potential CeD, and 300 healthy adults. Amplicons were fragmented and sequenced on the Illumina platform, and alleles and haplotypes were assigned by matching against the HLA‐international ImMunoGeneTics (IMGT) database.

Results

HLA‐DQA1*05:01 (odds ratio [OR] 8.39, 95% confidence interval [CI] 5.64–12.47) and HLA‐DQB1*02:01 (OR 8.59, 95% CI 5.75–12.83) were the genotypes that showed a risk association with symptomatic CeD. Among the haplotypes, HLA‐DQA1*05:01 ~ HLA‐DQB1*02:01 (OR 8.56, 95% CI 5.67–13.19) showed a strong risk association with symptomatic CeD. When comparing symptomatic CeD with subclinical forms (asymptomatic and potential) CeD, HLA‐DQA1*05:01 ~ HLA‐DQB1*02:01 (OR 2.34, 95% CI 1.61–3.43) was significantly associated with risk of symptomatic disease. The strength of association between the HLA‐DQA1*05:01 ~ HLA‐DQB1*02:01 haplotype and the CeD phenotype showed a gradient in the order typical > atypical > asymptomatic > potential CeD. Genotypes consistent with expression of HLA DQ2 and/or 8 were noted in 128 (80%) typical, 73 atypical (74%), 27 (60%) asymptomatic, and 52 (54%) potential CeD participants.

Conclusion

HLA‐DQA1*05:01 ~ HLA‐DQB1*02:01 (haplotype DQ2.5) showed a very strong risk association with symptomatic CeD in Indian patients. The strength of association showed a gradient of increase from potential to typical CeD, coinciding with a phenotypic change in the celiac iceberg.

Evaluation of Inner Exposure of Horses to Zearalenone (ZEN), Deoxynivalenol (DON) and Their Metabolites in Relation to Colic and Health-Related Clinical-Chemical Traits

Mycotoxin contaminated feed has been associated with colic of horses caused by intestinal disorders. Whether such disease conditions alter the intestinal toxin metabolism and transfer across a compromised mucosal barrier is unknown. A screening approach was used to relate blood residue levels of DON, ZEN and their metabolites to the status of the horses (sick vs. healthy). A total of 55 clinically healthy horses from 6 different farms with varying feeding background served as control for sick horses (N = 102) hospitalized due to colic. ZEN, alpha-zearalenol (ZEL), beta-ZEL and DON were detectable in peripheral blood as indicators for the inner exposure with significant farm effects for alpha- and beta-ZEL. However, the levels in sick horses were similar to all farms. Moreover, the proportion of beta-ZEL of all detected ZEN metabolites as an indicator for the degree of metabolism of ZEN was not different for sick horses but differed amongst the control farms. Although the incidence of DON in blood was generally low and not significantly different amongst healthy and sick horses, the positive samples were nearly exclusively found in sick horses suggesting either a higher toxin transfer, an association of DON with the development of colic or a different feeding background.

An unusual cause of granulomatous colitis: Behcet's disease

Intestinal involvement in Behcet's disease (BD) is uncommon. Differentiating it from close mimics like Crohn's Disease is difficult. Further, in asymptomatic cases, diagnostic challenges posed is still greater. A 17‐year‐old boy had history of recurrent oro‐genital ulcers, papulo‐pustular skin eruptions, ocular lesions and had presented with recent onset perianal abscess. Fecal calprotectin was elevated, and ileo‐colonoscopy showed ileocolonic ulcers of inflammatory nature. Clinical diagnosis of intestinal BD was made. Patients with BD having mucosal lesions may harbor asymptomatic intestinal lesions. Screening them with fecal calprotectin levels and if positive, with subsequent imaging and endoscopic biopsy with timely initiation of appropriate treatment in such asymptomatic cases help to control overall disease activity.

First description of Streptococcus lutetiensis from a diseased cat

This paper describes for the first time the isolation of Streptococcus lutetiensis in a cat with intestinal lymphoma. The Streptococcus bovis group has undergone significant taxonomic changes over the past two decades and, in 2002, Poyart et al. described two distinct novel species within the genus Streptococcus: Streptococcus lutetiensis and Streptococcus pasteurianus. The bovis group streptococci include commensal species and subspecies or opportunistic pathogens of humans and animals. The cat was referred to the Veterinary Teaching Hospital, University of Bologna for chronic diarrhoea associated with fresh blood. A diagnosis of intestinal lymphoma was advanced. S. lutetiensis was accidentally isolated from the faeces of the cat and identified through MALDI-TOF and 16s rRNA sequencing. The Kirby-Bauer test revealed that the isolate was resistant to enrofloxacin, erythromycin, clindamycin, marbofloxacin and tetracycline. The detection of S. lutetiensis in cat faeces might suggest that it could be a normal inhabitant of cat intestinal tract or that it could be involved in the manifestation of intestinal diseases. Since bacteria belonging to the S. bovis group are considered emerging pathogens, additional research is required to evaluate the role of S. lutetiensis in cats and its role in the transmission of antimicrobial resistance. SIGNIFICANCE AND IMPACT OF THE STUDY: In this study the isolation of Streptococcus lutetiensis from a cat with intestinal lymphoma was described for the first time. An antimicrobial susceptibility test performed by means of the disc diffusion method revealed that the isolate was resistant to enrofloxacin, erythromycin, clindamycin, marbofloxacin and tetracycline. Nowadays the ecological or pathogenetic role of S. lutetiensis in the gut of animals remains unclear but, even if its role as commensal bacterium was confirmed, the presence of multi-resistant S. lutetiensis in cat gut could favour the transmission of antimicrobial resistance to other bacteria.

Cystic fibrosis and AA amyloidosis: a survey in the French cystic fibrosis network

INTRODUCTION

To define the characteristics of CF patients developing AA amyloidosis.

METHODS

A 30-year retrospective survey conducted within the national French CF network to identify cases of CF associated with AA amyloidosis.

RESULTS

Nine cases of AA amyloidosis were identified (CF prevalence in France is approximately 6000 patients) and sufficient data were collected in six. The clinical presentation was renal disease in four cases, a compressive goiter in one case, and epigastric pain in one case. Organ involvement included kidney disease in all cases (proteinuria, with a median age at onset of 24 years, 4 cases with nephrotic syndrome, 5 with renal failure); gastrointestinal (4 cases with duodenal ulcer); thyroid (2 cases); and hepatobiliary system (3 cases). The median age at diagnosis of CF was 6.5 years. Five patients had pancreatic insufficiency. All patients had chronic respiratory infections requiring intravenous antibiotics several times a year. Five patients have died, at a median age of 29 years and a median duration of 6 years after the onset of proteinuria.

CONCLUSION

AA amyloidosis is a rare but morbid complication of CF. Renal involvement is predominant.

The endogenous nociceptin/orphanin FQ-NOP receptor system as a potential therapeutic target for intestinal disorders

In 1995, by reverse pharmacology approach, used here for the first time in the history of pharmacology, nociceptin/orphanin FQ (N/OFQ) has been discovered as the endogenous ligand of a preidentified receptor named opioid receptor like 1. Subsequent studies showed that N/OFQ and its receptor (N/OFQergic system) are widely distributed in central and peripheral nervous systems as well as in peripheral organs of human and animals, and represent a system that is involved in a very large range of biological functions such as pain perception, intestinal motility and secretion, immune modulation, stress. From the time of its discovery to now, a high number of NOP agonists and antagonists have been synthesized and tested in various pathologies. Nevertheless, none of the molecules targeting N/OFQergic system have currently succeeded in going through clinical trials concerning gut pathologies, indicating that further studies are required. The work from Dr. Fichna et al., published in the present issue of Neurogastroenterology and Motility, adds another brick in the wall of understanding the role of N/OFQergic system in IBS-D pathology by the pharmacological evaluation of a new NOP receptor agonist, SCH 221510, in animal models of intestinal alterations (diarrhea and visceral hyperalgesia). Interestingly, authors report clinical data confirming the involvement of N/OFQergic system in IBS-D patients and, consequently, suggest this system as a valuable therapeutic target for IBS-D pathology. This minireview aims to give a brief summary of experimental and clinical studies focusing on the N/OFQergic system as pharmacological target for the therapeutic treatment of intestinal pathologies such as IBS and IBD.

Helicobacter pylori and nonmalignant diseases

Peptic ulcer bleeding and recurrence rate are strongly linked to Helicobacter pylori infection even if nonsteroidal anti-inflammatory drugs (NSAIDs) play a relevant role in this setting. Further studies confirm that H. pylori eradication lowers the risk of recurrent peptic ulcer bleeding. Therefore, a test-and-treat strategy appears to be mandatory for patients with a history of ulcer bleeding and NSAIDs and/or aspirin use. Concerning gastroesophageal reflux disease (GERD), evidence clearly shows that H. pylori status has no effect on symptoms and treatment. Therefore, H. pylori treatment is not contraindicated in patients with GERD. The exact role of H. pylori in functional dyspepsia (FD) remains controversial. Novel possible mechanisms by which H. pylori may elicit dyspeptic symptoms include alterations of gastric motility, as well as endocrine and acid-secretory abnormalities. Hunger sensations, acid secretion, and gastrointestinal motility are regulated by ghrelin, particularly produced by the gastric enteroendocrine cell compartment. The improvement of symptoms correlates with enhanced plasma ghrelin levels. Apart from the need for more trials on this topic, these findings may give insight into the underlying pathophysiology of FD symptoms. Recent reports suggest that the presence of bacterial DNA in the oral cavity may be relevant to its transmission. A potential protective role of H. pylori on inflammatory bowel diseases needs to be better elucidated.

Diffused and sustained inhibitory effects of intestinal electrical stimulation on intestinal motility mediated via sympathetic pathway

OBJECTIVE

The aims were to investigate the energy-dose response effect of intestinal electrical stimulation (IES) on small bowel motility, to compare the effect of forward and backward IES, and to explore the possibility of using intermittent IES and mechanism of IES on intestinal motility.

MATERIALS AND METHODS

Five dogs implanted with a duodenal cannula and one pair of intestinal serosal electrodes were studied in five sessions: 1) energy-dose response study; 2) forward IES; 3) backward IES; 4) intermittent IES vs. continuous IES; 5) administration of guanethidine. The contractile activity and tonic pressure of the small intestine were recorded. The duration of sustained effect after turning off IES was manually calculated.

RESULTS

1) IES with long pulse energy dose dependently inhibited contractile activity and tonic pressure of the small intestine (p < 0.001). 2) The duration of sustained inhibitory effect of IES on the small intestine depended on the energy of IES delivered (p < 0.001). 3) The potency of the inhibitory effect was the same between forward and backward IES. 4) The efficacy of intermittent IES was the same as continuous IES in inhibiting motility of the small intestine. 5) Guanethidine blocked the inhibitory effect of IES on intestinal motility.

CONCLUSIONS

IES with long pulses inhibits small intestinal motility; the effect is energy-dose dependent, diffused, and sustained. Intermittent IES has the same efficacy as the continuous IES in inhibiting small intestinal motility. Forward and backward IES have similar inhibitory effects on small bowel motility. This IES-induced inhibitory effect is mediated via the sympathetic pathway.

New insights into probiotic mechanisms: a harvest from functional and metagenomic studies

There has been continued and expanding recognition of probiotic approaches for treating gastrointestinal and systemic disease, as well as increased acceptance of probiotic therapies by both the public and the medical community. A parallel development has been the increasing recognition of the diverse roles that the normal gut microbiota plays in the normal biology of the host. This advance has in turn has been fed by implementation of novel investigative technologies and conceptual paradigms focused on understanding the fundamental role of the microbiota and indeed all commensal bacteria, on known and previously unsuspected aspects of host physiology in health and disease. This review discusses current advances in the study of the host-microbiota interaction, especially as it relates to potential mechanisms of probiotics. It is hoped these new approaches will allow more rational selection and validation of probiotic usage in a variety of clinical conditions.