Intestinal Bacteria Maintain Adult Enteric Nervous System and Nitrergic Neurons via Toll-like Receptor 2-induced Neurogenesis in Mice

BACKGROUND & AIMS

The enteric nervous system (ENS) exists in close proximity to luminal bacteria. Intestinal microbes regulate ENS development, but little is known about their effects on adult enteric neurons. We investigated whether intestinal bacteria or their products affect the adult ENS via toll-like receptors (TLRs) in mice.

METHODS

We performed studies with conventional C57/BL6, germ-free C57/BL6, Nestin-creER^T2:tdTomato, Nestin-GFP, and ChAT-cre:tdTomato. Mice were given drinking water with ampicillin or without (controls). Germ-free mice were given drinking water with TLR2 agonist or without (controls). Some mice were given a blocking antibody against TLR2 or a TLR4 inhibitor. We performed whole gut transit, bead latency, and geometric center studies. Feces were collected and analyzed by 16S ribosomal RNA gene sequencing. Longitudinal muscle myenteric plexus (LMMP) tissues were collected, analyzed by immunohistochemistry, and levels of nitric oxide were measured. Cells were isolated from colonic LMMP of Nestin-creER^T2:tdTomato mice and incubated with agonists of TLR2 (receptor for gram-positive bacteria), TLR4 (receptor for gram-negative bacteria), or distilled water (control) and analyzed by flow cytometry.

RESULTS

Stool from mice given ampicillin had altered composition of gut microbiota with reduced abundance of gram-positive bacteria and increased abundance of gram-negative bacteria, compared with mice given only water. Mice given ampicillin had reduced colon motility compared with mice given only water, and their colonic LMMP had reduced numbers of nitrergic neurons, reduced neuronal nitric oxide synthase production, and reduced colonic neurogenesis. Numbers of colonic myenteric neurons increased after mice were switched from ampicillin to plain water, with increased markers of neurogenesis. Nestin-positive enteric neural precursor cells expressed TLR2 and TLR4. In cells isolated from the colonic LMMP, incubation with the TLR2 agonist increased the percentage of neurons originating from enteric neural precursor cells to approximately 10%, compared with approximately 0.01% in cells incubated with the TLR4 agonist or distilled water. Mice given an antibody against TLR2 had prolonged whole gut transit times; their colonic LMMP had reduced total neurons and a smaller proportion of nitrergic neurons per ganglion, and reduced markers of neurogenesis compared with mice given saline. Colonic LMMP of mice given the TLR4 inhibitor did not have reduced markers of neurogenesis. Colonic LMMP of germ-free mice given TLR2 agonist had increased neuronal numbers compared with control germ-free mice.

CONCLUSIONS

In the adult mouse colon, TLR2 promotes colonic neurogenesis, regulated by intestinal bacteria. Our findings indicate that colonic microbiota help maintain the adult ENS via a specific signaling pathway. Pharmacologic and probiotic approaches directed towards specific TLR2 signaling processes might be developed for treatment of colonic motility disorders related to use of antibiotics or other factors.

A Diet Low in Fermentable Oligo-, Di-, and Monosaccharides and Polyols Improves Quality of Life and Reduces Activity Impairment in Patients With Irritable Bowel Syndrome and Diarrhea

BACKGROUND & AIMS

We investigated the effects of a diet low in fermentable oligo-, di-, and monosaccharides and polyols (FODMAPs) vs traditional dietary recommendations on health-related quality of life (QOL), anxiety and depression, work productivity, and sleep quality in patients with irritable bowel syndrome and diarrhea (IBS-D).

METHODS

We conducted a prospective, single-center, single-blind trial of 92 adult patients with IBS-D (65 women; median age, 42.6 years) randomly assigned to groups placed on a diet low in FODMAPs or a modified diet recommended by the National Institute for Health and Care Excellence (mNICE) for 4 weeks. IBS-associated QOL (IBS-QOL), psychosocial distress (based on the Hospital Anxiety and Depression Scale), work productivity (based on the Work Productivity and Activity Impairment), and sleep quality were assessed before and after diet periods.

RESULTS

Eighty-four patients completed the study (45 in the low-FODMAP group and 39 in the mNICE group). At 4 weeks, patients on the diet low in FODMAPs had a larger mean increase in IBS-QOL score than did patients on the mNICE diet (15.0 vs 5.0; 95% CI, -17.4 to -4.3). A significantly higher proportion of patients in the low-FODMAP diet group had a meaningful clinical response, based on IBS-QOL score, than in the mNICE group (52% vs 21%; 95% CI, -0.52 to -0.08). Anxiety scores decreased in the low-FODMAP diet group compared with the mNICE group (95% CI, 0.46-2.80). Activity impairment was significantly reduced with the low-FODMAP diet (-22.89) compared with the mNICE diet (-9.44; 95% CI, 2.72-24.20).

CONCLUSIONS

In a randomized, controlled trial, a diet low in FODMAPs led to significantly greater improvements in health-related QOL, anxiety, and activity impairment compared with a diet based on traditional recommendations for patients with IBS-D. ClinicalTrials.gov, number NCT01624610.

Tongxie Formula Reduces Symptoms of Irritable Bowel Syndrome

BACKGROUND & AIMS

Irritable bowel syndrome (IBS) is the most common chronic gastrointestinal disorder, yet few drugs are effective in reducing symptoms. Approximately 50% of patients with IBS attempt herbal therapy at least once. We performed a randomized controlled trial to compare the efficacy of the herb formulation tongxie vs placebo or pinaverium (an antispasmodic agent) in reducing symptoms of IBS.

METHODS

We performed a trial of 1044 adult patients with IBS (based on Rome III criteria) at 5 hospitals in China, from August 2012 through January 2015. Subjects were randomly assigned (1:1:1) to groups given tongxie (a combination of A macrocephalae, P lactiflora, C reticulata, S divaricata, C pilosula, C wenyujin, C medica, and P cocos, along with other herbs, based on patient features), placebo, or pinaverium (50 mg tablets) 3 times daily for 4 weeks. Primary end points were significantly greater reductions in abdominal pain and Bristol stool score (before vs after the 4-week study period) in patients given tongxie compared with patients given placebo or pinaverium. Secondary end points were reductions in pain and stool frequencies and abdominal discomfort and its frequency.

RESULTS

Subjects given tongxie had significant reductions, before vs after the study period, in all 6 symptoms assessed, compared to patients given placebo (P < .001). A significantly higher proportion of patients given tongxie had increased stool consistency (75.6%) than patients given pinaverium (50.6%), and a significantly higher proportion of patients given tongxie had fewer daily stools (72.7%) than subjects given pinaverium (58.3%) (P < .001 for both). However, significantly higher proportions of patients given pinaverium had reduced pain (63.5%) and pain frequency (69.5%) than patients given tongxie (51.4% and 58.6%, respectively; P < .005 for both).

CONCLUSIONS

In a randomized controlled trial of patients with IBS in China, we found 4 weeks of tongxie to produce significantly greater reduction in symptoms than placebo, and greater increases in stool consistency and reductions in stool frequency, than patients given pinaverium. Tongxie can therefore be considered an effective alternative therapy for patients with IBS who do not respond well to conventional therapies. Clinicaltrials.gov no: NCT01641224.

Values From Three-dimensional High-resolution Anorectal Manometry Analysis of Children Without Lower Gastrointestinal Symptoms

BACKGROUND & AIMS

Three-dimensional high-resolution anorectal manometry (3DHRAM) provides a topographic image of pressure along the anal canal. We aimed to determine normal 3DHRAM values in children.

METHODS

We performed a prospective study of 61 children (34 male; mean age, 8.28 years) without any symptoms arising from the lower gastrointestinal tract who were evaluated at the Department of Pediatric Gastroenterology and Nutrition, Medical University of Warsaw, Poland. Manometry procedures were performed by using a rigid probe without medication. Pressure within the anal canal and 3D images of sphincters were measured. If possible, squeeze pressure and thresholds of sensation were evaluated. The population was divided into age groups of <5 years, 5-8 years, 9-12 years, and older than 12 years.

RESULTS

The mean resting and squeeze sphincter pressures were 83 ± 23 mm Hg and 191 ± 64 mm Hg, respectively. The mean length of the anal canal was 2.62 ± 0.68 cm and correlated with age (r = 0.49, P < .0001). The mean rectal balloon volume to elicit rectoanal inhibitory reflex was 15.7 ± 10.9 cm(3). The first sensation, urge, and discomfort were observed at balloon volumes of 24.4 ± 23.98 cm(3), 45.9 ± 34.55 cm(3), and 91.6 ± 50.17 cm(3), respectively. The mean resting pressure of the puborectalis muscle was 69 ± 14 mm Hg, whereas the mean squeeze pressure was 124 ± 33 mm Hg. There was no statistically significant difference in pressure parameters between age groups. We observed a positive correlation between age and balloon volume needed to elicit discomfort (r = 0.49, P < .001).

CONCLUSIONS

In a prospective study, we determined normal values from 3DHRAM analysis of children without symptoms arising from the lower gastrointestinal tract. There were no significant differences in pressure results between children of different sexes or ages. ClinicalTrials.gov number: NCT02236507.

Anxiety Is Linked to New-Onset Dyspepsia in the Swedish Population: A 10-Year Follow-up Study

BACKGROUND & AIMS

Functional dyspepsia (FD) is associated with anxiety but it is not clear if one causes the other. We investigated whether anxiety and depression precede the onset of FD (based on the modified Rome III criteria) and gastroesophageal reflux symptoms (GERS) in a population-based follow-up study.

METHODS

Participants from the Kalixanda study (n = 3000), randomly selected from the national population register of Sweden, were given the validated Abdominal Symptom Questionnaire 1998-2001; 1000 of these participants then were selected randomly to undergo esophagogastroduodenoscopy and were given the Abdominal Symptom Questionnaire along with the Hospital Anxiety and Depression Scale questionnaire. All eligible subjects who underwent endoscopy (n = 887) were invited to participate in a follow-up study in June-August 2010 and were given the same questionnaires. Data were analyzed by logistic regression.

RESULTS

Of the 703 subjects who completed the follow-up questionnaires (79.3%); 110 were found to have FD at baseline (15.6%) and 93 at the follow-up examination (13.3%); 48 of these were new cases of FD. GERS without organic disease was reported by 273 individuals (38.8%) at baseline and by 280 at follow-up examination (39.8%); 93 cases were new. Major anxiety was associated with FD at the follow-up evaluation (odds ratio [OR], 6.30; 99% confidence interval [CI], 1.64-24.16). Anxiety was associated with postprandial distress syndrome at baseline (OR, 4.83; 99% CI, 1.24-18.76) and at the follow-up examination (OR, 8.12; 99% CI, 2.13-30.85), but not with epigastric pain syndrome. Anxiety at baseline was associated with new-onset FD at the follow-up examination (OR, 7.61; 99% CI, 1.21-47.73), but not with GERS.

CONCLUSIONS

In a study of the Swedish population, anxiety at baseline, but not depression, increased the risk for development of FD by 7.6-fold in the next 10 years. Anxiety did not affect risk for GERS.

Lubiprostone increases spontaneous bowel movement frequency and quality of life in patients with chronic idiopathic constipation

BACKGROUND & AIMS

Lubiprostone is an activator of the type 2 chloride channel that facilitates spontaneous bowel movement (SBM). We performed phase 3 studies to determine whether lubiprostone increases the frequency of SBM in patients with chronic idiopathic constipation (CIC) in Japan, and whether long-term administration of lubiprostone increases the quality of life of patients with CIC.

METHODS

We performed a randomized, double-blind, placebo-controlled, phase 3 trial of lubiprostone. Patients with CIC (n = 124) were assigned randomly to groups given placebo (n = 62) or lubiprostone (48 μg/day; n = 62) for 4 weeks. The primary efficacy end point was the change from baseline in the weekly average number of SBMs after 1 week of administration. In a long-term study of efficacy and safety, 209 patients with CIC were given lubiprostone (24 μg twice daily) for 48 weeks.

RESULTS

Daily administration of lubiprostone induced a significantly greater change, from baseline, in the weekly average number of SBMs at week 1 (increase of 3.7 ± 2.8), compared with placebo (increase of 1.3 ± 1.8; P < .001). The frequency of SBMs during each week of the study period was significantly higher after subjects began receiving lubiprostone than at baseline (P < .0001 at all weeks). Long-term administration of lubiprostone significantly increased scores from the Short-Form health survey and irritable bowel syndrome quality-of-life questionnaire, compared with baseline. We did not observe any severe adverse reactions to lubiprostone.

CONCLUSIONS

In phase 3 studies in Japan, lubiprostone increased the weekly average number of SBMs and increased the quality of life of patients with CIC. Clinical Trial Notification of the Japanese Regulatory Authorities: 20-3296 and 20-3300.