Gastroduodenal motility

The oral microbiome and oral and upper gastrointestinal diseases

Background

Microbiomes are essential components of the human body, and their populations are substantial. Under normal circumstances, microbiomes coexist harmoniously with the human body, but disturbances in this equilibrium can lead to various diseases. The oral microbiome is involved in the occurrence and development of many oral and gastrointestinal diseases. This review focuses on the relationship between oral microbiomes and oral and upper gastrointestinal diseases, and therapeutic strategies aiming to provide valuable insights for clinical prevention and treatment.

Methods

To identify relevant studies, we conducted searches in PubMed, Google Scholar, and Web of Science using keywords such as "oral microbiome," "oral flora, " "gastrointestinal disease, " without any date restrictions. Subsequently, the retrieved publications were subject to a narrative review.

Results

In this review, we found that oral microbiomes are closely related to oral and gastrointestinal diseases such as periodontitis, dental caries, reflux esophagitis, gastritis, and upper gastrointestinal tumors (mainly the malignant ones). Oral samples like saliva and buccal mucosa are not only easy to collect, but also display superior sample stability compared to gastrointestinal tissues. Consequently, analysis of the oral microbiome could potentially serve as an efficient preliminary screening method for high-risk groups before undergoing endoscopic examination. Besides, treatments based on the oral microbiomes could aid early diagnosis and treatment of these diseases.

Conclusions

Oral microbiomes are essential to oral and gastrointestinal diseases. Therapies centered on the oral microbiomes could facilitate the early detection and management of these conditions.

Efficacy of Pistacia lentiscus Plant (Rumi Mastagi) in Comparison to Levosulpiride in Patients with Diabetic Gastroparesis: A Double-Blind Non-Inferior Randomised Control Trial Study

Introduction

Gastrointestinal neuropathies are frequently found in diabetic patients. The pathogenesis of diabetic gastroparesis (DG) is multifactorial. The usual treatment for DG includes dietary modifications, prokinetic and antiemetic agents. There is increasing demand for more effective medicines to treat DG. The current study was conducted on the Pistacia lentiscus stem extract to add to the armamentarium of DG treatment and to find the efficacy of P. lentiscus plant extract (mastic gum) in comparison to levosulpiride in DG for improvement in gastroparesis symptoms and gastric emptying scintigraphy (GES) in a single centric double-blind non-inferiority randomised control trial.

Methods

Thirty-eight individuals were recruited and equally randomised into two study groups based on Gastroparesis Cardinal Symptom Index (GCSI) score and TC99 Radionuclide GES, mastic gum group and levosulpiride group. Both pre and post-intervention (8 weeks) GCSI scores were calculated, GES was performed to quantify the improvement in gastric emptying. Power analysis was performed using G*POWER software version 3.1.9.7 and data analysis using SPSS 23.0, variables measured in mean ± standard deviation (SD). Various statistical tests were used such as independent t-test, Chi-square test or Fisher's exact test, Wilcox Mann-Whitney test, analysis of variance (ANOVA) test, and posthoc pairwise tests.

Results

The mastic gum is found effective in the improvement of 4 h gastric emptying percentage from the mean (SD) 76.60 (± 9.96) to mean (SD) 97.20 (2.17)% (P < 0.001). Mastic gum has the property of HbA1c reduction, which is more significant than that of levosulpiride (P = 0.044). Mastic gum also had significant Low density lipoprotein (LDL) (mg/dL) levels reduction, (P < 0.001), compared to levosupiride. An absolute increase was observed in haemoglobin (HB) level in mastic gum at a 2-month mean (SD) of 1.03 (0.77) (g/dL) (P-value <0.001).

Conclusions

To our knowledge, this is the first study to compare the effect of levosulpiride with mastic gum concerning improvement in diabetic gastroparesis (DG) using GES. In the study, mastic gum was found to have great properties to improve DG with many important pleiotropic effects.

Real-world safety and effectiveness of Pistacia lentiscus (mastic gum) in patients with diabetic gastroparesis: 24-week interim analysis postintervention

INTRODUCTION

Gastrointestinal neuropathies are frequently found in diabetic patients.

AIM

The aim of this study was to find out the safety, adverse reactions, and long-term effectiveness of Pistacia lentiscus plant extract (mastic gum) in diabetic gastroparesis (DG) with respect to sustainable improvement in gastroparesis symptoms (Gastrointestinal Cardinal Symptom Index [GCSI] score) by observational follow-up study of a single-centric double-blind noninferiority randomized control trial.

MATERIALS AND METHODS

Thirty-eight individuals were recruited and equally randomized in two study groups based on GCSI score and TC99 radionuclide gastric emptying scintigraphy (GES), i.e. the mastic gum group and the levosulpiride group. After 24 weeks, the GCSI score was recalculated in both the groups, and patients were evaluated for the safety, adverse reactions, and long-term effectiveness of mastic gum and the standard drug levosulpiride.

RESULTS

In the extended study, mean GCSI score changes at 24 weeks were statistically significant (P < 0.001) (t-test) between the two groups. In the mastic gum arm, the change in mean GCSI score at 24 weeks was statistically nonsignificant mean ± (standard deviation [SD]) 16.7± (3.81) compared to the GCSI score at 2-month postintervention mean (SD) 16.35± (2.27) (intragroup P = 0.89) (repeated measures ANOVA). It strongly indicates that mastic gum provided a sustainable improvement in DG symptoms in comparison to levosulpiride, with excellent subjective well-being postintervention, without any obvious significant adverse effects.

CONCLUSION

Six-month (24-week) interim analysis of patients suggests that mastic gum gives a sustainable improvement in DG symptoms without any obvious adverse effects as compared to levosulpiride.

Functional Dyspepsia: Diagnostic and Therapeutic Approaches

Functional dyspepsia is a common functional gastrointestinal (GI) disorder of gastroduodenal origin, diagnosed clinically in the presence of prototypical symptoms of epigastric pain and meal-related symptoms, and without structural explanation. The most recent diagnostic criteria provide for two functional dyspepsia subtypes, epigastric pain syndrome (EPS) and post-prandial distress syndrome (PDS) based on the predominant symptom pattern. The evaluation of dyspepsia should keep laboratory, imaging, and invasive testing to a minimum, as extensive or repetitive investigations are of rather low diagnostic yield in the absence of localizing symptoms or alarm features. Factors with etiopathologic relationships to functional dyspepsia include micro-inflammation, GI infections, abnormalities of gastroduodenal motility, visceral hypersensitivity, disturbances along the brain-gut axis, and psychological factors; all of these causative mechanisms have potential to partially explain symptoms in some functional dyspepsia patients, thus providing a rationale for the efficacy of a diversity of therapeutic approaches to functional dyspepsia. Management of dyspepsia symptoms relies upon both pharmacologic treatments and non-pharmacologic approaches, including psychological and complementary interventions. The evidence in support of established functional dyspepsia therapies is reviewed, and forms the basis for an effective functional dyspepsia treatment strategy emphasizing the patient's current symptom severity, pattern, and impact on the function and quality of life of the individual.

Mfge8 attenuates human gastric antrum smooth muscle contractions

Coordinated gastric smooth muscle contraction is critical for proper digestion and is adversely affected by a number of gastric motility disorders. In this study we report that the secreted protein Mfge8 (milk fat globule-EGF factor 8) inhibits the contractile responses of human gastric antrum muscles to cholinergic stimuli by reducing the inhibitory phosphorylation of the MYPT1 (myosin phosphatase-targeting subunit (1) subunit of MLCP (myosin light chain phosphatase), resulting in reduced LC20 (smooth muscle myosin regulatory light chain (2) phosphorylation. Mfge8 reduced the agonist-induced increase in the F-actin/G-actin ratios of β-actin and γ-actin1. We show that endogenous Mfge8 is bound to its receptor, α8β1 integrin, in human gastric antrum muscles, suggesting that human gastric antrum muscle mechanical responses are regulated by Mfge8. The regulation of gastric antrum smooth muscles by Mfge8 and α8 integrin functions as a brake on gastric antrum mechanical activities. Further studies of the role of Mfge8 and α8 integrin in regulating gastric antrum function will likely reveal additional novel aspects of gastric smooth muscle motility mechanisms.

Changes in oral flora of patients with functional dyspepsia

To explore the changes in oral flora in people with functional dyspepsia (FD). Unstimulated saliva was collected from 21 FD patients diagnosed according to the Rome IV criteria and from 12 healthy controls (HCs) for 16SrRNA sequencing. The pH of saliva samples and community periodontal index (CPI) were tested. The prevalence of small intestinal bacterial overgrowth (SIBO) was obtained by the methane-and hydrogen-based breath test. At the phylum level, FD patients had a higher relative abundance of Spirochaetes and a lower relative abundance of Fusobacteria, TM7 and Proteobacteria than HCs (p < 0.01). In the saliva, Kingella and Abiotrophia genus levels showed significant changes between the FD and HC groups (p < 0.01). Salivary species level marker Intermedia was significantly different between FD and HC groups (p < 0.01). The oral pH of FD patients was higher than that of HCs (p < 0.01). The mean CPI of the FD group was 1.52 and that of the HC group was 0.17 (p < 0.01). Moreover, 71.4% of the FD group was positive for SIBO. The oral flora of FD patients was different from that of HCs. Spirochaetes, Kingella, Abiotrophia, and Intermedia may be diagnostic indicators of FD.

Repeated Gastric Motility Measurement Affects Gastric Motility and Epigastric Symptom Sensation

Background: Gastric motility is an important determinant of gastric emptying, epigastric symptom generation, and intolerance to food. Motility is classically assessed directly using manometry or an intragastric balloon. These diagnostic methods are perceived as stressful and invasive, which, by itself might influence the readout of these assessments. Our hypothesis was that with repeated exposure to an invasive motility test the outcome would be different.

Methods: Gastric motility was assessed with a custom-made orogastric balloon catheter in 10 healthy subjects naive to intubation. A motility index ranging from 0 (no motility) to 1 (maximum motility) was calculated in the fasted state for 3.5 h. Symptoms were surveyed with visual analog scales of 100 mm. Results are presented as median (interquartile range).

Results: Motility index during visit 1 [0.40 (0.37–0.59)] was lower compared to visit 2 [0.50 (0.45–0.66); not significant] and 3 [0.63 (0.50–0.71); p = 0.016]. Nausea and pain scores were significantly higher during visit 1 (35 (2.8–126) and 103 (88–125) mm, respectively) compared with visit 3 [1 (2.8–26) mm (p = 0.016) and 75 (30–100) mm (p = 0.008), respectively]. No adverse events were observed.

Conclusions: Repeated exposure to an invasive method to assess motility resulted in more vigorous motility and lower symptom scores. Caution is warranted when interpreting functional assessments, as prior exposure to invasive tests might confound the obtained results through habituation.

Insights into the evaluation and management of dyspepsia: recent developments and new guidelines

Dyspepsia is a very common gastrointestinal (GI) condition worldwide. We critically examine the recommendations of recently published guidelines for the management of dyspepsia, including those produced jointly by the American College of Gastroenterology and the Canadian Association of Gastroenterology, and those published by the UK National Institute for Health and Care Excellence. Dyspepsia is a symptom complex, characterized by a range of upper GI symptoms including epigastric pain or burning, early satiety, and post-prandial fullness. Although alarm features are used to help prioritize access to upper GI endoscopy, they are of limited utility in predicting endoscopic findings, and the majority of patients with dyspepsia will have no organic pathology identified at upper GI endoscopy. These patients are labelled as having functional dyspepsia (FD). The Rome IV criteria, which are used to define FD, further subclassify patients with FD as having either epigastric pain syndrome or post-prandial distress syndrome, depending on their predominant symptoms. Unfortunately, the Rome criteria perform poorly at identifying FD without the need for upper GI endoscopy. This has led to the investigation of alternative diagnostic approaches, including whether a capsaicin pill or combined serum biomarkers can accurately identify patients with FD. However, there is insufficient evidence to support either of these approaches at the present time. Patients with FD should be tested for H. pylori infection and be prescribed eradication therapy if they test positive. If they continue to have symptoms following this, then a trial of treatment with a proton pump inhibitor (PPI) should be given for up to 8 weeks. In cases where symptoms fail to adequately respond to PPI treatment, a tricyclic antidepressant may be of benefit, and should be continued for 6 to 12 months in patients who respond. Prokinetics demonstrate limited efficacy for treating FD, but could be considered if other strategies have failed. However, there are practical difficulties due to their limited availability in some countries and the risk of serious side effects. Patients with FD who fail to respond to drug treatments should be offered psychological therapy, where available. Overall, with the exception of recommendations relating to H. pylori testing and the prescription of PPIs, which are made on the basis of high-quality evidence, the evidence underpinning other elements of dyspepsia management is largely of low-quality. Consequently, there are still many aspects of the evaluation and management of dyspepsia that require further research.

Feasibility of intraperitoneal placental-derived mesenchymal stem cell injection in stomachs of diabetic mice

BACKGROUND AND AIM

Diabetic gastropathy is associated with loss of interstitial cells of Cajal and autonomic neuropathy. Effective management for diabetic gastropathy is still unavailable. This study was aimed to confirm the pathogenetic changes in diabetic gastropathy and to examine the effect of treatment with placental-derived mesenchymal stem cells (PDMSCs) in stomachs of animal models.

METHODS

Fourteen non-obese diabetic/ShiLtJ mice of 8 weeks were bled until week 30. Diabetes mellitus developed in 10 out of 14 mice, which all survived with insulin. The mice were grouped into three groups: nondiabetic group (n = 4), diabetic sham group (n = 5), and diabetic PDMSC group (n = 5) all of which were treated with intraperitoneal PDMSCs injection at week 30. All mice were killed at week 34, and the stomachs were examined by immunohistochemical stain with c-kit and neuronal nitric oxide synthase antibodies.

RESULTS

The number of c-kit positive cells in stomach decreased significantly in the diabetic sham group compared with that in the nondiabetic group (21.2 ± 6.7 vs 88.0 ± 29.3, P = 0.006) but increased with PDMSC treatment (21.2 ± 6.7 vs 64.0 ± 15.1, P = 0.02). The positive rate of neuronal nitric oxide synthase in neural plexus was also significantly lower in the diabetic sham group than in the nondiabetic group (22.3% ± 18.5% vs 48.0% ± 22.7%, P = 0.003) but increased with PDMSC treatment (22.3% ± 18.5% vs 43.3% ± 20.5%, P = 0.03).

CONCLUSIONS

Interstitial cells of Cajal and neural plexus decreased in stomachs of mice with diabetes mellitus but were significantly repaired with intraperitoneal injection of PDMSC.

Contractile Protein Expression and Phosphorylation and Contractility of Gastric Smooth Muscles from Obese Patients and Patients with Obesity and Diabetes

Ingested food is received, mixed, and ground into chyme by distinct gastric motility patterns. Diabetes impairs gastric muscle function, but the mechanisms underlying diabetes-induced gastric muscle dysfunction are unknown. Here, we compared the expression and phosphorylation of Ca²⁺ sensitization and contractile proteins in human gastric muscles from obese nondiabetic and diabetic patients. We also compared the spontaneous phasic contractions and the contractile responses evoked by electrical field stimulation of cholinergic motor neurons. Fundus and antrum muscles were obtained from sleeve gastrectomies and were used in in vitro myobath contractile studies and for capillary electrophoresis and immunodetection of γ-actin, CPI-17, pT38-CPI-17, MYPT1, pT853-MYPT1, pT696-MYPT1, myosin light chain (MYL9), pS19-MYL9, myosin light chain kinase (MYLK), protein phosphatase-1δ (PP1δ), and Rho-associated kinase (ROCK2). In diabetic fundus muscles, MYLK, ROCK2, and PP1δ expression was unchanged; MYPT1 and CPI-17 expression was decreased; and the pT853/MYPT1 and pT38/CPI-17 ratios, but not the pT696/MYPT1 ratio, were increased. Although MYL9 expression was increased, the pS19/MYL9 ratio was unchanged in diabetic fundus muscles. In diabetic antrum muscles, MYLK and MYL9 expression was unchanged, but ROCK2, CPI-17, and PP1δ expression was decreased. The pT38/CPI-17 ratio was unchanged, while the pS19/MYL9, pT853/MYPT1, and pT696/MYPT1 ratios were decreased, consistent with the reduced ROCK2 expression. The frequencies of spontaneous phasic contractions from nondiabetic and diabetic gastric fundus and antrum muscles did not significantly differ from each other, regardless of age, sex, or diabetic status. The fold increases in the contractions of diabetic fundus and antrum muscles in response to increased frequencies of electrical field stimulation were significantly lower compared to nondiabetic fundus and antrum muscles. The altered contractile responses and the protein expression and phosphorylation in gastric muscles of obese patients with diabetes illustrate the importance of understanding how smooth muscle Ca²⁺ sensitization mechanisms contribute to gastric motility.

Impairments of the primary afferent nerves in a rat model of diabetic visceral hyposensitivity

Background

Diabetic neuropathy in visceral organs such as the gastrointestinal (GI) tract is still poorly understood, despite that GI symptoms are among the most common diabetic complications. The present study was designed to explore the changes in visceral sensitivity and the underlying functional and morphological deficits of the sensory nerves in short-term diabetic rats. Here, we compared the colorectal distension (CRD)-induced visceromotor response (VMR, an index of visceral pain) in vivo, the mechanosensitivity of colonic afferents ex vivo as well as the expression of protein gene product (PGP) 9.5 and calcitonin gene-related peptide (CGRP) in colon between diabetic (3–6 weeks after streptozotocin injection) and control (age-matched vehicle injection) rats.

Results

VMR was markedly decreased in the diabetic compared to the control rats. There was a significant decrease in multiunit pelvic afferent nerve responses to ramp distension of the ex vivo colon and single unit analysis indicated that an impaired mechanosensitivity of low-threshold and wide dynamic range fibers may underlie the afferent hyposensitivity in the diabetic colon. Fewer PGP 9.5- or CGRP-immunoreactive fibers and lower protein level of PGP 9.5 were found in the colon of diabetic rats.

Conclusions

These observations revealed the distinctive feature of colonic neuropathy in short-term diabetic rats that is characterized by a diminished sensory innervation and a blunted mechanosensitivity of the remnant sensory nerves.

The microbiota-gut-brain axis in functional gastrointestinal disorders

Functional gastrointestinal disorders (FGIDs) are highly prevalent and pose a significant burden on health care and society, and impact patients' quality of life. FGIDs comprise a heterogeneous group of disorders, with unclear underlying pathophysiology. They are considered to result from the interaction of altered gut physiology and psychological factors via the gut-brain axis, where brain and gut symptoms are reciprocally influencing each other's expression. Intestinal microbiota, as a part of the gut-brain axis, plays a central role in FGIDs. Patients with Irritable Bowel Syndrome, a prototype of FGIDs, display altered composition of the gut microbiota compared with healthy controls and benefit, at the gastrointestinal and psychological levels, from the use of probiotics and antibiotics. This review aims to recapitulate the available literature on FGIDs and microbiota-gut-brain axis.

Peripheral and central nervous contribution to gastrointestinal symptoms in diabetic patients with autonomic neuropathy

BACKGROUND & AIMS

Long-term diabetes mellitus (DM) has been associated with neuronal changes in the enteric, peripheral and/or central nervous system. Moreover, abnormal visceral sensation and gastrointestinal (GI) symptoms are seen in up to 75% of patients. To explore the role of diabetic autonomic neuropathy (DAN) in patients with long-standing DM, we investigated psychophysical responses and neuronal activity recorded as evoked brain potentials and dipolar source modelling.

METHODS

Fifteen healthy volunteers and 14 type-1 DM patients with DAN were assessed with a symptom score index characterizing upper GI abnormalities. Multichannel (62) electroencephalography was recorded during painful electrical stimulation of the lower oesophagus. Brain activity to painful stimulations was modelled using Brain Electrical Source Analysis (besa).

RESULTS

Diabetic patients had higher stimulus intensities to evoke painful sensation (p ≤ 0.001), longer latencies of N2 and P2 components (both p ≤ 0.001), and lower amplitudes of P1-N2 and N2-P2 complexes (p ≤ 0.001; p = 0.02). Inverse modelling of brain sources showed deeper bilateral insular dipolar source localization (p = 0.002). Symptom score index was negatively correlated with the depth of insular activity (p = 0.004) and positively correlated with insular dipole strength (p = 0.03).

CONCLUSION

DM patients show peripheral and central neuroplastic changes. Moreover, the role of abnormal insular processing may explain the appearance and persistence of GI symptoms related to DAN. This enhanced understanding of DAN may have future clinical and therapeutical implications.

The role of cholecystokinin 1 receptor in prolactin inhibited gastric emptying of male rat

Background/Aims

Prolactin (PRL) is essential for the lactating mammals, while cholecystokinin (CCK) does inhibit gastric emptying (GE). Present study attempted to determine whether both peptides interacted on the male rat GE, particularly the role of putative CCK1 receptor.

Methods

Acute hyperprolactinemia of male rats was induced by the intraperitoneal injection of ovine PRL (oPRL) in several divided doses 15 minutes before motility study. Rat chronic hyperprolactinemia was induced by the graft of 2 pituitary glands into the capsule of left kidney, while control rats received cerebral cortex graft only. Motility study was conducted 6 weeks later after graft surgery. Fifteen minutes after the intragastric feeding of radiochromium, rat was sacrificed to measure GE via the distribution of radioactivities within stomach and intestine. Among the CCK1 receptor blocking study using lorglumide, rats were divided to receive the regimens in terms of oPRL-vehicle plus lorglumide-vehicle, oPRL plus lorglumide-vehicle, oPRL-vehicle plus lorglumide and oPRL plus lorglumide. Plasma CCK level was measured using a homemade radioimmunoassay kit.

Results

Compared to vehicle treatment, acute hyperprolactinemic rats under highest dose (2.0 mg/kg) of oPRL treatment showed delayed GE (70.6% ± 3.0% vs 42.1% ± 6.6%, P < 0.05). Chronic hyperprolactinemic rats under graft surgery also showed inhibited GE (70.5% ± 1.7% vs 54.5% ± 4.7%, P < 0.05). Both models finally obtained elevated plasma CCK levels (P < 0.05). Lorglumide itself did not influence GE, however, delayed GE under oPRL treatment was restored following the concomitant lorglumide treatment.

Conclusions

Our study suggests that PRL may delay male rat GE via a mechanism of endogenous CCK activation involving the peripheral CCK1 receptor.

Diabetic gastrointestinal autonomic neuropathy: current status and new achievements for everyday clinical practice

Gastrointestinal symptoms occur frequently among patients with diabetes mellitus and are associated with considerable morbidity. Diabetic gastrointestinal autonomic neuropathy represents a complex disorder with multifactorial pathogenesis, which is still not well understood. It appears to involve a spectrum of metabolic and cellular changes that affect gastrointestinal motor and sensory control. It may affect any organ in the digestive system. Clinical manifestations are often underestimated, and therefore autonomic neuropathy should be suspected in all diabetic patients with unexplained gastrointestinal symptoms. Advances in technology have now enabled assessment of gastrointestinal motor function. Moreover, novel pharmacological approaches, along with endoscopic and surgical treatment options, contribute to improved outcomes. This review summarises the progress achieved in diabetic gastrointestinal autonomic neuropathy during the last years, focusing on clinical issues of practical importance to the everyday clinician.