Idiopathic gastroparesis is associated with specific transcriptional changes in the gastric muscularis externa

Current Concepts in Gastroparesis and Gastric Neuromuscular Disorders-Pathophysiology, Diagnosis, and Management

Upper gastrointestinal concerns including gastroparesis-like symptoms affect a large portion of the population, and determining the culprit condition can be difficult due to largely shared symptoms, clinical course, pathophysiology, and treatment pathways. The understanding of gastric neuromuscular disorders (GNDs) is emerging as a heterogeneous group encompassing conditions from gastroparesis to functional dyspepsia with chronic nausea, early satiety, bloating, or abdominal pain, irrespective of gastric emptying. This article aims to review the current concepts in gastroparesis and GNDs including pathophysiology, diagnosis, and management. While some established standards in their diagnosis and management exist, a number of novel diagnostics are becoming available. Durable therapeutic options are notably limited for such common conditions with chronic and debilitating symptoms, and neuromodulators may play a key role in symptom control, which has been previously under-recognized and underutilized. Advances in both pharmacologic treatment targets as well as noninvasive and invasive interventions and devices show promise in improving the experience of patients with gastroparesis-like symptoms. At this time, treatment of GNDs requires comprehensive multidisciplinary care from providers to achieve successful treatment outcomes.

Pharmacologic treatments for gastroparesis

Gastroparesis is a neurogastrointestinal disorder of motility in which patients experience symptoms of nausea, vomiting, bloating, early satiety, postprandial fullness, upper abdominal discomfort or pain, and delayed gastric emptying of solids based on scintigraphy or stable isotope breath test when mechanical obstruction has been excluded. Symptoms of gastroparesis may result from diverse pathophysiological mechanisms, including antroduodenal hypomotility, pylorospasm, increased gastric accommodation, and visceral hypersensitivity. The most common etiologies of gastroparesis are idiopathic, diabetic, and postsurgical, and less frequent causes are neurodegenerative disorders (Parkinson's disease), myopathies (scleroderma, amyloidosis), medication-induced (glucagon-like peptide-1 agonists and opioid agents), and paraneoplastic syndrome. This review addresses pharmacologic management of gastroparesis including prokinetic and antiemetic agents, pharmacologic agents targeting the pylorus, and effects of neuromodulators. SIGNIFICANCE STATEMENT: Gastroparesis is a neurogastrointestinal motility disorder characterized by delayed gastric emptying without mechanical obstruction with numerous upper gastrointestinal symptoms, including nausea and vomiting. The management of gastroparesis involves nutritional support, medications, and procedures. The only Food and Drug Administration-approved medication for gastroparesis is metoclopramide. This article reviews the pharmacology and efficacy of all classes of antiemetics or prokinetic effects used in gastroparesis. There is still a considerable unmet need for efficacious medications specifically for the treatment of gastroparesis, especially in refractory cases.

Stretchable Device for Simultaneous Measurements of Contractility and Electrophysiology of Neuromuscular Tissue in the Gastrointestinal Tract

Devices interfacing with biological tissues can provide valuable insights into function, disease, and metabolism through electrical and mechanical signals. However, certain neuromuscular tissues, like those in the gastrointestinal tract, undergo significant strains of up to 40%. Conventional inextensible devices cannot capture the dynamic responses in these tissues. This study introduces electrodes made from poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and polydimethylsiloxane (PDMS) that enable simultaneous monitoring of electrical and mechanical responses of gut tissue. The soft PDMS layers conform to tissue surfaces during gastrointestinal movement. Dopants, including Capstone FS-30 and polyethylene glycol, are explored to enhance the conductivity, electrical sensitivity to strain, and stability of the PEDOT:PSS. The devices are fabricated using shadow masks and solution-processing techniques, providing a faster and simpler process than traditional clean-room-based lithography. Tested on ex vivo mouse colon and human stomach, the device recorded voltage changes of up to 300 µV during contraction and distension consistent with muscle activity, while simultaneously recording resistance changes of up to 150% due to mechanical strain. These devices detect and respond to chemical stimulants and blockers, and can induce contractions through electrical stimulation. They hold great potential for studying and treating complex disorders like irritable bowel syndrome and gastroparesis.

Applications of gastric peroral endoscopic myotomy in the treatment of upper gastrointestinal tract disease

Gastric peroral endoscopic myotomy (G-POME) is an emerging minimally invasive endoscopic technique involving the establishment of a submucosal tunnel around the pyloric sphincter. In 2013, Khashab et al used G-POME for the first time in the treatment of gastroparesis with enhanced therapeutic efficacy, providing a new direction for the treatment of gastroparesis. With the recent and rapid development of G-POME therapy technology, progress has been made in the treatment of gastroparesis and other upper digestive tract diseases, such as congenital hypertrophic pyloric stenosis and gastric sleeve stricture, with G-POME. This article reviews the research progress and future prospects of G-POME for the treatment of upper digestive tract gastrointestinal diseases.

A Randomized, Controlled Trial of Efficacy and Safety of Cannabidiol in Idiopathic and Diabetic Gastroparesis

BACKGROUND & AIMS

Cannabis (delta-9-tetrahydrocannabinol), a nonselective cannabinoid-receptor agonist, relieves nausea and pain. Cannabidiol (CBD), a cannabinoid receptor 2 inverse agonist with central effects, also reduces gut sensation and inflammation. We compared the effects of 4 weeks of treatment with pharmaceutical CBD vs placebo in patients with idiopathic or diabetic (diabetes mellitus) gastroparesis.

METHODS

We performed a randomized, double-blinded, placebo-controlled study of CBD twice daily (Epidiolex escalated to 20 mg/kg/d; Jazz Pharmaceuticals, Dublin, Ireland) in patients with nonsurgical gastroparesis with delayed gastric emptying of solids (GES). Symptoms were assessed by the Gastroparesis Cardinal Symptom Index Daily Diary. After 4 weeks of treatment, we measured GES, gastric volumes, and Ensure (Abbott Laboratories, Abbott Park, IL) satiation test (1 kcal/mL, 30 mL/min) to assess volume to comfortable fullness and maximum tolerance. Patients underwent specific FAAH and CNR1 genotyping. Statistical analysis compared 2 treatments using analysis of variance including baseline measurements and body mass index as covariates.

RESULTS

Among 44 patients (32 idiopathic, 6 diabetes mellitus type 1, and 6 diabetes mellitus type 2), 5 patients did not tolerate full-dose escalation; 3 withdrew before completing 4 weeks of treatment (2 placebo, 1 CBD); 95% completed 4 weeks of treatment and diaries. Compared with placebo, CBD reduced the total Gastroparesis Cardinal Symptom Index score (P = .008), inability to finish a normal-sized meal (P = .029), number of vomiting episodes/24 hours (P = .006), and overall symptom severity (P = .034). Patients treated with CBD had a higher volume to comfortable fullness and maximum tolerance and slower GES. FAAH rs34420 genotype significantly impacted nutrient drink ingestion. The most common adverse events reported were diarrhea (14 patients), fatigue (8 patients), headache (8 patients), and nausea (7 patients).

CONCLUSIONS

CBD provides symptom relief in patients with gastroparesis and improves the tolerance of liquid nutrient intake, despite slowing of GES.

CLINICALTRIALS

gov NCT #03941288.

Gastroparesis syndromes: emerging drug targets and potential therapeutic opportunities

INTRODUCTION

Gastroparesis (Gp) and related disorders such as chronic unexplained nausea and vomiting and functional dyspepsia, known as gastropareis syndromes (GpS), have large unmet needs. Mainstays of GpS treatments are diet and drugs.

AREAS COVERED

The purpose of this review is to explore potential new medications and other therapies for gastroparesis. Before discussing possible new drugs, the currently used drugs are discussed. These include dopamine receptor antagonists, 5-hydroxytryptamine receptor agonists and antagonists, neurokinin-1 receptor antagonists and other anti-emetics. The article also considers future drugs that may be used for Gp, based on currently known pathophysiology.

EXPERT OPINION

Gaps in knowledge about the pathophysiology of gastroparesis and related syndromes are critical to developing therapeutic agents that will be successful. Recent major developments in the gastroparesis arena are related to microscopic anatomy, cellular function, and pathophysiology. The major challenges moving forward will be to develop the genetic and biochemical correlates of these major developments in gastroparesis research.

A New Paradigm Shift in Gastroparesis Management

Gastroparesis, once regarded as a rare disease, is difficult to diagnose and challenging to treat; there were many breakthrough advances in the 2010s, shifting the paradigm of the understanding of this complex entity and its management. Similar to diabetes, its increasing prevalence reflects increased accessibility to diagnostic modalities and suggests that gastroparesis was underacknowledged in the past. Major developments in the three main aspects of the disease include the discovery of smooth muscle cells, interstitial cells of Cajal, PDGFRα+ cells syncytium, rather than interstitial cells of Cajal alone, as the main gastric pacemaker unit; the development of validated point-of-care diagnostic modalities such as a wireless motility capsule, the carbon 13-labeled breath test, and impedance planimetry; and the introduction of novel minimally invasive therapeutic options such as newer pharmacologic agents and gastric peroral endoscopic pyloromyotomy. All aspects of these advances will be discussed further in this review.

Gastroparesis

Gastroparesis is characterized by symptoms suggestive of, and objective evidence of, delayed gastric emptying in the absence of mechanical obstruction. This review addresses the normal emptying of solids and liquids from the stomach and details the myogenic and neuromuscular control mechanisms, including the specialized function of the pyloric sphincter, that result in normal emptying, based predominantly on animal research. A clear understanding of fundamental mechanisms is necessary to comprehend derangements leading to gastroparesis, and additional research on human gastric muscles is needed. The section on pathophysiology of gastroparesis considers neuromuscular diseases that affect nonsphincteric gastric muscle, disorders of the extrinsic neural control, and pyloric dysfunction that lead to gastroparesis. The potential cellular basis for gastroparesis is attributed to the effects of oxidative stress and inflammation, with increased pro-inflammatory and decreased resident macrophages, as observed in full-thickness biopsies from patients with gastroparesis. Predominant diagnostic tests involving measurements of gastric emptying, the use of a functional luminal imaging probe, and high-resolution antral duodenal manometry in characterizing the abnormal motor functions at the gastroduodenal junction are discussed. Management is based on supporting nutrition; dietary interventions, including the physical reduction in particle size of solid foods; pharmacological agents, including prokinetics and anti-emetics; and interventions such as gastric electrical stimulation and pyloromyotomy. These are discussed briefly, and comment is added on the potential for individualized treatments in the future, based on optimal gastric emptying measurement and objective documentation of the underlying pathophysiology causing the gastroparesis.

New Developments in Prokinetic Therapy for Gastric Motility Disorders

Prokinetic agents amplify and coordinate the gastrointestinal muscular contractions to facilitate the transit of intra-luminal content. Following the institution of dietary recommendations, prokinetics are the first medications whose goal is to improve gastric emptying and relieve symptoms of gastroparesis. The recommended use of metoclopramide, the only currently approved medication for gastroparesis in the United States, is for a duration of less than 3 months, due to the risk of reversible or irreversible extrapyramidal tremors. Domperidone, a dopamine D2 receptor antagonist, is available for prescription through the FDA's program for Expanded Access to Investigational Drugs. Macrolides are used off label and are associated with tachyphylaxis and variable duration of efficacy. Aprepitant relieves some symptoms of gastroparesis. There are newer agents in the pipeline targeting diverse gastric (fundic, antral and pyloric) motor functions, including novel serotonergic 5-HT4 agonists, dopaminergic D2/3 antagonists, neurokinin NK1 antagonists, and ghrelin agonist. Novel targets with potential to improve gastric motor functions include the pylorus, macrophage/inflammatory function, oxidative stress, and neurogenesis. In the current review, we discuss the use of pharmacological approaches with potential to enhance motor functions in the management of gastroparesis.

Gastric Mucosal Immune Profiling and Dysregulation in Idiopathic Gastroparesis

INTRODUCTION

It is unclear how immune perturbations may influence the pathogenesis of idiopathic gastroparesis, a prevalent functional disorder of the stomach which lacks animal models. Several studies have noted altered immune characteristics in the deep gastric muscle layer associated with gastroparesis, but data are lacking for the mucosal layer, which is endoscopically accessible. We hypothesized that immune dysregulation is present in the gastroduodenal mucosa in idiopathic gastroparesis and that specific immune profiles are associated with gastroparesis clinical parameters.

METHODS

In this cross-sectional prospective case-control study, routine endoscopic biopsies were used for comprehensive immune profiling by flow cytometry, multicytokine array, and gene expression in 3 segments of the stomach and the duodenal bulb. Associations of immune endpoints with clinical parameters of gastroparesis were also explored.

RESULTS

The gastric mucosa displayed large regional variation of distinct immune profiles. Furthermore, several-fold increases in innate and adaptive immune cells were found in gastroparesis. Various immune cell types showed positive correlations with duration of disease, proton pump inhibitor dosing, and delayed gastric emptying.

DISCUSSION

This initial observational study showed immune compartmentalization of the human stomach mucosa and significant immune dysregulation at the level of leukocyte infiltration in idiopathic gastroparesis patients that extends to the duodenum. Select immune cells, such as macrophages, may correlate with clinicopathological traits of gastroparesis. This work supports further mucosal studies to advance our understanding of gastroparesis pathophysiology.

United European Gastroenterology (UEG) and European Society for Neurogastroenterology and Motility (ESNM) consensus on gastroparesis

BACKGROUND

Gastroparesis is a condition characterized by epigastric symptoms and delayed gastric emptying (GE) rate in the absence of any mechanical obstruction. The condition is challenging in clinical practice by the lack of guidance concerning diagnosis and management of gastroparesis.

METHODS

A Delphi consensus was undertaken by 40 experts from 19 European countries who conducted a literature summary and voting process on 89 statements. Quality of evidence was evaluated using grading of recommendations assessment, development, and evaluation criteria. Consensus (defined as ≥80% agreement) was reached for 25 statements.

RESULTS

The European consensus defined gastroparesis as the presence of symptoms associated with delayed GE in the absence of mechanical obstruction. Nausea and vomiting were identified as cardinal symptoms, with often coexisting postprandial distress syndrome symptoms of dyspepsia. The true epidemiology of gastroparesis is not known in detail, but diabetes, gastric surgery, certain neurological and connective tissue diseases, and the use of certain drugs recognized as risk factors. While the panel agreed that severely impaired gastric motor function is present in these patients, there was no consensus on underlying pathophysiology. The panel agreed that an upper endoscopy and a GE test are required for diagnosis. Only dietary therapy, dopamine-2 antagonists and 5-HT4 receptor agonists were considered appropriate therapies, in addition to nutritional support in case of severe weight loss. No consensus was reached on the use of proton pump inhibitors, other classes of antiemetics or prokinetics, neuromodulators, complimentary, psychological, or more invasive therapies. Finally, there was consensus that gastroparesis adversely impacts on quality of life and healthcare costs and that the long-term prognosis of gastroparesis depends on the cause.

CONCLUSIONS AND INFERENCES

A multinational group of European experts summarized the current state of consensus on definition, symptom characteristics, pathophysiology, diagnosis, and management of gastroparesis.

United European Gastroenterology (UEG) and European Society for Neurogastroenterology and Motility (ESNM) consensus on gastroparesis

BACKGROUND

Gastroparesis is a condition characterized by epigastric symptoms and delayed gastric emptying (GE) rate in the absence of any mechanical obstruction. The condition is challenging in clinical practice by the lack of guidance concerning diagnosis and management of gastroparesis.

METHODS

A Delphi consensus was undertaken by 40 experts from 19 European countries who conducted a literature summary and voting process on 89 statements. Quality of evidence was evaluated using grading of recommendations assessment, development, and evaluation criteria. Consensus (defined as ≥80% agreement) was reached for 25 statements.

RESULTS

The European consensus defined gastroparesis as the presence of symptoms associated with delayed GE in the absence of mechanical obstruction. Nausea and vomiting were identified as cardinal symptoms, with often coexisting postprandial distress syndrome symptoms of dyspepsia. The true epidemiology of gastroparesis is not known in detail, but diabetes, gastric surgery, certain neurological and connective tissue diseases, and the use of certain drugs recognized as risk factors. While the panel agreed that severely impaired gastric motor function is present in these patients, there was no consensus on underlying pathophysiology. The panel agreed that an upper endoscopy and a GE test are required for diagnosis. Only dietary therapy, dopamine-2 antagonists and 5-HT4 receptor agonists were considered appropriate therapies, in addition to nutritional support in case of severe weight loss. No consensus was reached on the use of proton pump inhibitors, other classes of antiemetics or prokinetics, neuromodulators, complimentary, psychological, or more invasive therapies. Finally, there was consensus that gastroparesis adversely impacts on quality of life and healthcare costs and that the long-term prognosis of gastroparesis depends on the cause.

CONCLUSIONS AND INFERENCES

A multinational group of European experts summarized the current state of consensus on definition, symptom characteristics, pathophysiology, diagnosis, and management of gastroparesis.

Gastroparesis in the 2020s: New Treatments, New Paradigms

PURPOSE OF REVIEW

This review highlights recent work that will lead to near-term advances in the understanding and treatment of gastroparesis (Gp).

RECENT FINDINGS

Major current advancements in the pathophysiology of Gp, include recognition of the SIP syncytium as the pacemaking unit rather than ICC alone and that Gp may be part of a pan-enteric autoimmune and/or autonomic disorder with macrophage imbalance. The development of newer techniques to assess gastric emptying (gastric emptying breath test and wireless motility capsule) and pyloric distensibility (EndoFLIP®) are allowing clinicians better characterization of their patients. In addition to pharmaceutical compounds in the pipeline, neuromodulation and endosurgical techniques, such as G-POEM, may help address refractory Gp. We expect that the 2020 decade will witness exciting developments. Treatments targeting gastrointestinal motility, immunological dysfunction, and inflammatory mediators will be evaluated. We anticipate future studies will be guided by biomarkers correlated with patient outcomes and therapeutic efficacy to establish new paradigms in the management of Gp.

Transcriptome profiling reveals significant changes in the gastric muscularis externa with obesity that partially overlap those that occur with idiopathic gastroparesis

Background

Gastric emptying is impaired in patients with gastroparesis whereas it is either unchanged or accelerated in obese individuals. The goal of the current study was to identify changes in gene expression in the stomach muscularis that may be contributing to altered gastric motility in idiopathic gastroparesis and obesity.

Methods

Quantitative real time RT-PCR and whole transcriptome sequencing were used to compare the transcriptomes of lean individuals, obese individuals and either lean or obese individuals with idiopathic gastroparesis.

Results

Obesity leads to an increase in mRNAs associated with muscle contractility whereas idiopathic gastroparesis leads to a decrease in mRNAs associated with PDGF BB signaling. Both obesity and idiopathic gastroparesis were also associated with similar alterations in pathways associated with inflammation.

Conclusions

Our findings show that obesity and idiopathic gastroparesis result in overlapping but distinct changes in the gastric muscularis transcriptome. Increased expression of mRNAs encoding smooth muscle contractile proteins may be contributing to the increased gastric motility observed in obese subjects, whereas decreased PDGF BB signaling may be contributing to the impaired motility seen in subjects with idiopathic gastroparesis.

Electronic supplementary material

The online version of this article (10.1186/s12920-019-0550-3) contains supplementary material, which is available to authorized users.

The Role of Prostaglandins in Disrupted Gastric Motor Activity Associated With Type 2 Diabetes

Patients with diabetes often develop gastrointestinal motor problems, including gastroparesis. Previous studies have suggested this gastric motor disorder was a consequence of an enteric neuropathy. Disruptions in interstitial cells of Cajal (ICC) have also been reported. A thorough examination of functional changes in gastric motor activity during diabetes has not yet been performed. We comprehensively examined the gastric antrums of Lepob mice using functional, morphological, and molecular techniques to determine the pathophysiological consequences in this type 2 diabetic animal model. Video analysis and isometric force measurements revealed higher frequency and less robust antral contractions in Lepob mice compared with controls. Electrical pacemaker activity was reduced in amplitude and increased in frequency. Populations of enteric neurons, ICC, and platelet-derived growth factor receptor α+ cells were unchanged. Analysis of components of the prostaglandin pathway revealed upregulation of multiple enzymes and receptors. Prostaglandin-endoperoxide synthase-2 inhibition increased slow wave amplitudes and reduced frequency of diabetic antrums. In conclusion, gastric pacemaker and contractile activity is disordered in type 2 diabetic mice, and this appears to be a consequence of excessive prostaglandin signaling. Inhibition of prostaglandin synthesis may provide a novel treatment for diabetic gastric motility disorders.

Gastroparesis is associated with decreased FOXF1 and FOXF2 in humans, and loss of FOXF1 and FOXF2 results in gastroparesis in mice

BACKGROUND AND AIMS

The transcription factors FOXF1 and FOXF2 have been implicated in the development of the gastrointestinal tract but their role in adults or in gastrointestinal diseases is poorly understood. We have recently shown that expression of serum response factor (SRF), a transcription factor whose activity is modulated by FOXF proteins, is decreased in the stomach muscularis of patients with gastroparesis. The aim of the current study was to determine whether FOXF expression is decreased in gastroparesis patients and whether loss of FOXF1 and/or FOXF2 from adult smooth muscle is sufficient to impair gastric emptying in mice.

METHODS

Full-thickness stomach biopsy samples were collected from control subjects and from patients with gastroparesis. mRNA was isolated from the muscularis externa, and FOXF mRNA expression levels were determined by quantitative reverse transcriptase (RT)-PCR. Foxf1 and Foxf2 were knocked out together and separately from smooth muscle cells in adult mice, and the subsequent effect on liquid gastric emptying and contractile protein expression was determined.

KEY RESULTS

Expression of FOXF1 and FOXF2 is decreased in smooth muscle tissue from gastroparesis patients. Knockout of Foxf1 and Foxf2 together, but not alone, from mouse smooth muscle resulted in delayed liquid gastric emptying. Foxf1/2 double knockout mice had decreased expression of smooth muscle contractile proteins, SRF, and myocardin in stomach muscularis.

CONCLUSIONS AND INFERENCES

Our findings suggest that decreased expression of FOXF1 and FOXF2 may be contributing to the impaired gastric emptying seen in gastroparesis patients.

Pathophysiology of idiopathic gastroparesis and implications for therapy

OBJECTIVES

Idiopathic gastroparesis is a gastric motility disorder characterized by chronic upper gastrointestinal symptoms and delayed gastric emptying without an identifiable underlying condition. This review summarizes recent understanding of the pathophysiology and treatment of idiopathic gastroparesis.

MATERIALS AND METHODS

Structured literature search in the PubMed, Embase and ClinicalTrials.gov databases.

RESULTS

Idiopathic gastroparesis involves several alterations in gastric motility and sensation, including delayed gastric emptying, altered myoelectrical activity, impaired fundic accommodation, visceral hypersensitivity and disturbances in antropyloroduodenal motility and coordination. Multiple cellular changes have been identified, including depletion of interstitial cells of Cajal (ICC) and enteric nerves, as well as stromal fibrosis. The underlying cause of these changes is not fully understood but may be an immune imbalance, including loss of anti-inflammatory heme-oxygenase-1 positive (HO-1) macrophages. There is currently no causal therapy for idiopathic gastroparesis. The treatment ladder consists of dietary measures, prokinetic and antiemetic medications, and varying surgical or endoscopic interventions, including promising pyloric therapies. There are ongoing trials with several novel medications, raising hopes for future treatment.

CONCLUSIONS

Patients with idiopathic gastroparesis present several pathophysiological alterations in the stomach, where depletion of ICC is of special importance. Treatment is currently focused on alleviating symptoms through dietary adjustments, medication or surgical or endoscopic interventions.

Current and future impact of clinical gastrointestinal research on patient care in diabetes mellitus

The worldwide rise in the prevalence of obesity supports the need for an increased interaction between ongoing clinical research in the allied fields of gastrointestinal medicine/surgery and diabetes mellitus. There have been a number of clinically-relevant advances in diabetes, obesity, and metabolic syndrome emanating from gastroenterological research. Gastric emptying is a significant factor in the development of upper gastrointestinal symptoms. However, it is not the only mechanism whereby such symptoms occur in patients with diabetes. Disorders of intrinsic pacing are involved in the control of stomach motility in patients with gastroparesis; on the other hand, there is limited impact of glycemic control on gastric emptying in patients with established diabetic gastroparesis. Upper gastrointestinal functions related to emptying and satiations are significantly associated with weight gain in obesity. Medications used in the treatment of diabetes or metabolic syndrome, particularly those related to pancreatic hormones and incretins affect upper gastrointestinal tract function and reduce hyperglycemia and facilitate weight loss. The degree of gastric emptying delay is significantly correlated with the weight loss in response to liraglutide, a glucagon-like peptide-1 analog. Network meta-analysis shows that liraglutide is one of the two most efficacious medical treatments of obesity, the other being the combination treatment phentermine-topiramate. Interventional therapies for the joint management of obesity and diabetes mellitus include newer endoscopic procedures, which require long-term follow-up and bariatric surgical procedure for which long-term follow up shows advantages for individuals with diabetes. Newer bariatric procedures are presently undergoing clinical evaluation. On the horizon, combination therapies, in part directed at gastrointestinal functions, appear promising for these indications. Ongoing and future gastroenterological research when translated to care of individuals with diabetes mellitus should provide additional options to improve their clinical outcomes.

Gastroparesis

Gastroparesis is a disorder characterized by delayed gastric emptying of solid food in the absence of a mechanical obstruction of the stomach, resulting in the cardinal symptoms of early satiety, postprandial fullness, nausea, vomiting, belching and bloating. Gastroparesis is now recognized as part of a broader spectrum of gastric neuromuscular dysfunction that includes impaired gastric accommodation. The overlap between upper gastrointestinal symptoms makes the distinction between gastroparesis and other disorders, such as functional dyspepsia, challenging. Thus, a confirmed diagnosis of gastroparesis requires measurement of delayed gastric emptying via an appropriate test, such as gastric scintigraphy or breath testing. Gastroparesis can have idiopathic, diabetic, iatrogenic, post-surgical or post-viral aetiologies. The management of gastroparesis involves: correcting fluid, electrolyte and nutritional deficiencies; identifying and treating the cause of delayed gastric emptying (for example, diabetes mellitus); and suppressing or eliminating symptoms with pharmacological agents as first-line therapies. Several novel pharmacologic agents and interventions are currently in the pipeline and show promise to help tailor individualized therapy for patients with gastroparesis.

Gastroduodenal motility disorders

PURPOSE OF REVIEW

This review summarizes recent progress in the epidemiology, pathophysiology and treatment of gastroduodenal motility disorders with an emphasis on functional dyspepsia and gastroparesis.

RECENT FINDINGS

Pathophysiological research has focused on the association of delayed emptying and impaired accommodation with symptom pattern. Studies also confirmed the presence of altered mucosal integrity and low-grade immune activation in the duodenum in functional dyspepsia, while changes in numbers of interstitial cells of Cajal and myenteric neurons were confirmed in gastroparesis. Treatment advances in gastroparesis include new prokinetics such as the ghrelin receptor agonist relamorelin and the antiemetic agent aprepitant. The efficacy and use of neuromodulators were reviewed and new management guidelines for functional dyspepsia were published.

SUMMARY

Pathophysiological research has focused on cellular changes in gastroparesis and gastroduodenal motility disorders. New treatments include relamorelin and aprepitant for gastroparesis.

New developments in the treatment of gastroparesis and functional dyspepsia

Functional dyspepsia (FD) and gastroparesis are frequent causes of upper gastrointestinal symptoms such as postprandial fullness, early satiation, epigastric pain or burning, upper abdominal bloating, bothersome belching, nausea and vomiting. The underlying pathophysiological mechanisms are heterogeneous and involved mechanisms such as abnormal gastric motility (accommodation, emptying), visceral hypersensitivity, low grade mucosal inflammation and cellular changes in enteric nerves, muscle or interstitial cells of Cajal. Patient-reported outcomes for evaluating treatment efficacy in these conditions were recently developed and validated. Prokinetic agents, which enhance gastric motility, are used for treating both gastroparesis and FD. In FD, besides acid suppressive therapy and Helicobacter pylori eradication, neuromodulators and drugs that enhance gastric accommodation can be applied. In gastroparesis, anti-emetics may also provide symptom relief. Novel approaches under evaluation in these conditions are the fundus relaxing agents acotiamide and buspirone and the antidepressant mirtazapine in FD. For gastroparesis, recently studied agents include the prokinetic ghrelin agonist relamorelin, the prokinetic serotonergic agents velusetrag and prucalopride, the anti-emetic aprepitant and per-endoscopic pyloric myotomy procedures.

Transcriptomic signatures reveal immune dysregulation in human diabetic and idiopathic gastroparesis

BACKGROUND

Cellular changes described in human gastroparesis have revealed a role for immune dysregulation, however, a mechanistic understanding of human gastroparesis and the signaling pathways involved are still unclear.

METHODS

Diabetic gastroparetics, diabetic non-gastroparetic controls, idiopathic gastroparetics and non-diabetic non-gastroparetic controls underwent full-thickness gastric body biopsies. Deep RNA sequencing was performed and pathway analysis of differentially expressed transcripts was done using Ingenuity®. A subset of differentially expressed genes in diabetic gastroparesis was validated in a separate cohort using QT-PCR.

RESULTS

111 genes were differentially expressed in diabetic gastroparesis and 181 in idiopathic gastroparesis with a log2fold difference of | ≥ 2| and false detection rate (FDR) < 5%. Top canonical pathways in diabetic gastroparesis included genes involved with macrophages, fibroblasts and endothelial cells in rheumatoid arthritis, osteoarthritis pathway and differential regulation of cytokine production in macrophages and T helper cells by IL-17A and IL-17F. Top canonical pathways in idiopathic gastroparesis included genes involved in granulocyte adhesion and diapedesis, agranulocyte adhesion and diapedesis, and role of macrophages, fibroblasts and endothelial cells in rheumatoid arthritis. Sixty-five differentially expressed genes (log2fold difference | ≥ 2|, FDR < 5%) were common in both diabetic and idiopathic gastroparesis with genes in the top 5 canonical pathways associated with immune signaling. 4/5 highly differentially expressed genes (SGK1, APOLD1, CXCR4, CXCL2, and FOS) in diabetic gastroparesis were validated in a separate cohort of patients using RT-PCR. Immune profile analysis revealed that genes associated with M1 (pro inflammatory) macrophages were enriched in tissues from idiopathic gastroparesis tissues compared to controls (p < 0.05).

CONCLUSIONS

Diabetic and idiopathic gastroparesis have both unique and overlapping transcriptomic signatures. Innate immune signaling likely plays a central role in pathogenesis of human gastroparesis.