Pankaj Jay Pasricha

Proper organization of the enteric nervous system (ENS) is critical for normal gastrointestinal (GI) physiology. Inflammatory bowel disease (IBD) disrupts key GI functions, including bowel motility. However, in many IBD patients, motility disorders persist even during remission, suggesting an irreversible ENS defect secondary to IBD. Here, we show that postinflammatory GI motility dysfunction arises from structural remodeling of the ENS, driven by a combination of neuronal loss and neurogenesis. During mucosal inflammation, enteric neurons upregulate CCL2 expression, facilitating the recruitment of monocytes into the myenteric plexus within the intestinal muscle. Monocyte-derived macrophages infiltrate the myenteric ganglia, contributing to excessive ENS remodeling and postinflammatory motility dysfunction. This neuroimmune axis is counterbalanced by a hypoxia-induced stress response in enteric neurons mediated by HIF1α. Enhancing the neuron-intrinsic hypoxia pathway limits ENS remodeling and preserves motility. In summary, this study presents a mechanistic model of postinflammatory GI motility dysfunction and proposes a therapeutic strategy to maintain ENS integrity and function during inflammation.

Functional dyspepsia is a common but serious medical syndrome that can induce weight loss and food aversion and may be associated with increased risks of hospitalization and death. It probably comprises several different and as yet incompletely characterized disorders. Patients with local mucosal microinflammation driven by an aberrant Th2 response may represent an important subgroup. There is overlap with other gastrointestinal syndromes, particularly irritable bowel syndrome and gastroesophageal reflux disease, and patients with overlap have more severe symptoms. There is no approved drug for functional dyspepsia. Treatment is empirical and directed at symptoms and consists of acid suppressants and low-dose tricyclic antidepressants (and other neuromodulators) along with appropriate nutritional and psychological support.

Background and Aims Nausea exacerbations in patients with gastroparesis and functional dyspepsia (FD) require the use of rescue medications with concomitant adverse effects. We hypothesized that non-invasive vagal nerve stimulation (nVNS) may provide an effective and safer alternative for such symptoms. Methods This pilot study included 41 patients with chronic nausea, attributed to gastric etiology with or without delayed gastric emptying. After a one-week observation period, patients self-administered nVNS for exacerbations of nausea: 4 weeks on one side of the neck (left or right based on the patient’s preference), followed by a 2-week washout and then another 4 weeks of nVNS on the other side. The primary endpoint was a reduction in the use of anti-nausea rescue medications. Results Compared to baseline, nVNS reduced the average number of rescue medications used per day by half. The initial side of stimulation did not appear to influence the outcome. Although the use of nVNS in this study was not designed to influence chronic sustained symptoms, robust changes were also seen in abdominal pain, reflux, indigestion, constipation, depression, and some autonomic symptoms. Paradoxically, daily vomiting episodes increased during the 4-week period after nVNS was initiated but remained steady thereafter. Conclusion “As-needed” nVNS may reduce the use of rescue medications for exacerbations of nausea. Additionally, several relatively unexpected benefits across a variety of other symptoms were observed. These results should inform larger randomized sham-controlled trials in these disorders with limited therapeutic alternatives. ClinicalTrials.gov registration number NCT04857281. Date of registration, 2021–04–20.

INTRODUCTION: Chronic neurogastroduodenal disorders are heterogeneous and thought to lie on a spectrum of disease encompassing both sensory and neuromuscular pathologies. Abnormalities of interstitial cells of Cajal (ICC), a subset of which generate pacemaker signals and subsequently motility, have been implicated in their pathophysiology. We systematically reviewed the literature to pool ICC deficits observed in chronic neurogastroduodenal disorders. METHODS: Studies quantifying gastric ICC from the corpus or antrum, in adult patients with gastroparesis, functional dyspepsia (FD), or chronic nausea and vomiting syndromes (CNVS) were analyzed (PROSPERO: CRD42024613226). MEDLINE, Embase and CENTRAL databases were searched systematically. Random effects meta-analyses were used to compare ICC counts by disorder group with subgroup analysis by quantification methodology. RESULTS: Overall, 2,158 studies were screened and 22 included. Comparative studies (n = 12) showed patients with chronic neurogastroduodenal disorders (n = 167 with gastroparesis, n = 19 with FD ± CNVS) had lower ICC counts than nondiabetic controls (n = 130); standardized mean difference −1.58, 95% confidence interval −2.09 to −1.07, P < 0.0001, with more severe deficits in gastroparesis compared to FD ± CNVS (standardized mean difference [SMD] −0.44, P = 0.048). A spectrum of ICC deficits was evident in a subgroup of studies using gold-standard methods with c-KIT antibody and 4',6-diamidino-2-phenylindole-stained nuclei confirmation (7 studies, 246 patients: mean ICC counts 2.29 in gastroparesis vs 3.49 in FD ± CNVS, and 5.27 in controls; P < 0.001 all comparisons). Most studies were at high risk of bias (n = 21). DISCUSSION: Marked depletion of ICC is a consistent finding in neurogastroduodenal disorders. A spectrum of disease is revealed, with greater depletion associated with delayed emptying. Techniques for clinically defining ICC-driven gastric neuromuscular dysfunction should be prioritized.

Background and Aims: Visceral pain is a cardinal symptom of many disorders affecting the gut. Modulators of gamma-aminobutyric acid (GABA) such as benzodiazepines may attenuate colonic pain but the specific contribution of peripheral GABAA receptors remains unclear as these agents have prominent central effects. Methods: Using medicinal chemistry optimization of the benzodiazepine scaffold, we developed a novel and potent benzodiazepine-based positive allosteric modulator (PAM) of GABAA receptors, Li633, with no significant central nervous system (CNS) penetration. Results: The locomotor activity of rats placed in an open field was unchanged with Li633 at doses up to 30 mg/kg, confirming its lack of a CNS effect. LI-633 produced robust potentiation of GABA-induced inward current, with EC50 values ranging from 8 nM (α5β2γ2) to 128 nM (α3β2γ2). In vitro electrophysiological studies confirmed its ability to reduce excitability of human dorsal root ganglion (DRG) neurons. LI-633 potentiated muscimol-induced GABAergic currents in rat DRG neurons in a dose-dependent manner, with an EC ₅₀ of 70.4 nM. In vivo, LI-633 significantly attenuated visceral hypersensitivity and pain behavior in a rat model of irritable bowel syndrome (IBS) and functional dyspepsia (FD). In the IBS model, administration of the drug also resulted in decreased excitability of colon-specific DRG neurons and significantly reduced the colonic afferent response to balloon distention as measured by recordings of neural activity in dorsal ganglia rootlets. Conclusions: These findings highlight the potential of targeting peripheral GABAA receptors for pain management in IBS and other disorders associated with visceral hypersensitivity.

Type 2 diabetes (T2D) and obesity are chronic metabolic diseases with global morbidity and mortality. Decades of evidence from surgical and endoscopic procedures bypassing the duodenum underscore the duodenum’s critical role in regulating glycemia and body weight. Although metabolic surgeries and endoscopic procedures are effective, their invasiveness, cost, and scalability limit patient access. We developed an orally administered mucin complexing polymeric (MCP) drug, designed to replicate duodenal exclusion physiology. MCPs, intended to have electrostatic and covalent cross-linkages with mucin glycoproteins, form extended network structures with resulting alteration of mucus barrier properties. Selective targeting of the duodenum is achieved via pH-based activation chemistry. Following screening for physiochemical properties, pharmacokinetics, and efficacy, GLY-200 emerged as the lead drug candidate replicating duodenal exclusion physiology with improved glycemia, reduced body weight, and modulation of gut hormones in rodent models. This targeted oral therapy holds promise for treatment of T2D and obesity by mimicking duodenal exclusion without the invasiveness of surgery or endoscopic procedures.

INTRODUCTION: There is an urgent need for effective and safe treatment of gastroparesis. Metopimazine, a selective, peripherally restricted dopamine D ₂ receptor antagonist, is used in France for the symptomatic treatment of nausea and vomiting and chemotherapy-induced nausea and vomiting. The aim of this study is to assess the safety and efficacy of oral NG101, the mesylate salt of metopimazine, for the treatment of gastroparesis. METHODS: We conducted a 12-week phase 2 multicenter trial with NG101 5, 10, and 20 mg 4 times a day versus placebo. The primary end point was the change in mean nausea severity from the Diabetic and Idiopathic Gastroparesis Symptoms Daily Diary (DIGS-DD) during weeks 7–12 of the Treatment Period from baseline. The DIGS-DD measured nausea, abdominal pain, early satiety, postprandial fullness, and vomiting at their worst in the past 24 hours using a 0-10 point numeric rating scale. Patient Global Impression of Change questionnaires, including nausea, were assessed weekly using a 7-point balanced ordinal score. RESULTS: Of 161 randomized participants (45.3% diabetic and 54.7% idiopathic), mean DIGS-DD nausea severity scores decreased from baseline during weeks 7–12 in all treatment groups, but these improvements were not statistically significant compared with placebo. However, there were statistically significant improvements in nausea Patient Global Impression of Change during weeks 1–12 for all treatment groups compared with placebo. Trends in safety and efficacy favored patients with idiopathic gastroparesis compared with those with diabetic gastroparesis. DISCUSSION: While NG101 did not meet statistical significance in its primary end point for reducing nausea severity, it demonstrated a favorable safety profile and significant improvement in some secondary end points. Further study is needed to determine whether NG101 is an effective treatment for patients with idiopathic gastroparesis.