Society: AGA

Background: Idiopathic gastroparesis (IG) is an increasingly prevalent subtype of gastroparesis and causes significant morbidity and decreased quality of life. Prior studies have shown loss of Interstitial Cells of Cajal (ICC), key regulators of gastrointestinal motility, as well as anti-inflammatory macrophages in gastroparesis. Our aim was to determine druggable molecules and signaling for human IG using a deep multiomics approach through untargeted transcriptomics and proteomics on gastric muscle tissue.

Methods: We enrolled 13 IG patients (43±2 yrs, 10 F) and 18 non-diabetic controls (NDC; 46±10 yrs, 14 F) patients from Gastroparesis Clinical Research Consortium sites and Mayo Clinic, respectively. Bulk RNA-seq and Gel-based Liquid Chromatography/Mass-Spectrometry (LC-MS) were performed on mucosa-free gastric muscle. Differentially expressed genes and proteins were determined. Gene Set Enrichment Analysis and Search Tool for Retrieval of Interacting Genes and Proteins (STRING) were used to generate signalling pathways. Next, transcriptomic, and proteomic datasets were integrated. EnrichmentMap (EM) analysis in Cytoscape was used to determine networks of integrated STRING pathways. Finally, CiberSort was used to determine distribution of immune cell markers.

Results: RNA-seq detected 16755 genes, of which, 2569 (1338 up, 1231 down in IG compared to NDC) were significantly different (FDR<0.05, FC≥|1.5|). Mitochondrial genes involved in oxidative phosphorylation (OXPHOS; COX6C, SDHA, SDHB) and apoptosis (AIFM1, GHITM, HTRA2), as well as OXPHOS pathways (KEGG, Hallmark, FDR<0.001) were increased in IG. Using CiberSort, a significant increase in memory B-cell, and CD8+ T-cell, and a decrease in M2-associated (anti-inflammatory) macrophage markers were found in IG. Proteomics analysis detected 6444 named proteins, of which, ~50% were significantly different (FDR<0.05, FC≥|1.5|; 1485 up, 1541 down in IG). Top pathways (Hallmark: “Oxidative Phosphorylation”; Reactome: “Electron Transport Chain”, FDR<0.001), and proteins (TRAP1, WASL, SDHA) were noted. Overlap of the 2 datasets revealed 1241 significantly different gene-protein pairs (574 up, 667 down in IG). EM analysis showed that network joining “Signaling by SCF-Kit”, “Kit receptor Signaling”, and “PDGFR-beta signaling” pathways as the largest downregulated network, whereas “OXPHOS system in mitochondria” and “Metabolism” was the primary upregulated network in IG (Figure 1).

Conclusions: Our deep multiomics profiling of gastric muscularis propria in IG has uncovered oxidative phosphorylation and mitochondrial dysfunction, as well as confirmed Kit-signaling to be important in pathophysiology of IG. Loss of genes associated with anti-inflammatory macrophages, and upregulation of memory B-cell, and cytotoxic CD8+ T-cells further makes a case for determining immunobiology of idiopathic gastroparesis.

Figure 1 (A) IG group had downregulated Kit-associated network, and (B) upregulated OXPHOS and Mitochondrial network. Pathways connected to form a network based on Jaccard similarity coefficient of 0.5

Figure 1 (A) IG group had downregulated Kit-associated network, and (B) upregulated OXPHOS and Mitochondrial network. Pathways connected to form a network based on Jaccard similarity coefficient of 0.5

Background: Medical cannabis (^Δ9THC) is used to relieve nausea and pain, and the non-selective cannabinoid receptor (CBR) agonist dronabinol delays gastric emptying (GE) and enhances gastric accommodation (GA). Cannabidiol (CBD), a selective CBR2 agonist with limited effects in the central nervous system, may modulate effects of endocannabinoids on CBR1. CBD also affects sensation as inverse agonist of G protein-coupled receptors 3, 6, and 12, desensitization of TRPV1, TRPV2 and TRPA1 receptors and anti-inflammatory effects (via CBR2). We studied an FDA-approved oral formulation of purified CBD (100mg/mL). Aim: To compare pharmacodynamics and clinical effects of 4 weeks’ treatment with pharmaceutical grade CBD and placebo on GE of solids, fasting gastric volume (FGV), GA, satiation, and symptom response endpoints in patients with non-surgical gastroparesis. Methods: We performed a randomized, double-blind, placebo-control (1:1 ratio) 4-week study of oral CBD b.i.d. (up to 10mg/kg/day using FDA dose escalation guidance) in patients with non-surgical gastroparesis and delayed GE (postprandial GE ≤25% emptied at 2 hours, or ≤75% at 4 hours). Symptoms were assessed by the validated Gastroparesis Cardinal Symptom Index Daily Diary (GCSI). At baseline and after 4 weeks’ treatment, all patients underwent measurements of GE of solids, gastric volumes (FGV, GA), and maximum tolerated volume (MTV) during Ensure^® (1kcal/mL) satiation test ingested 30mL/min. All data collected in participants were analyzed. Statistical analysis compared 2 treatments for all endpoints, using baseline measurements and BMI as co-variates (expressed as least square means). Results: Table 1 shows demographics and baseline variables of gastroparesis (29 idiopathic, 6 type 1 diabetes, and 6 type 2 diabetes). Four patients did not tolerate full dose escalation; 3 withdrew before completing 4 weeks’ treatment (2 on placebo, 1 on CBD). However, 95% completed at least 2 weeks of treatment and diaries. Table 2 summarizes the effects of cannabidiol and placebo treatment in gastroparesis. CBD reduced the total GCSI score compared to placebo and improved symptoms of inability to finish a normal-sized meal, number of vomiting episodes in 24 hours, and overall gastroparesis symptom severity. Patients treated with CBD had higher MTV during satiation test. CBD group had longer GE lag time, which was also observed at baseline. CBD delayed GE at 2 hours, but there were no differences in GE T_1/2, proportion emptied at 4 hours, or GA. The most common adverse events reported were diarrhea (13), fatigue (8), headache (8), and nausea (7). Conclusions: Pharmaceutical grade CBD provides symptom relief in patients with non-surgical gastroparesis by improving the tolerance of nutrient intake and reducing the number of emesis, without deleterious effects on GA or overall GE.

<b>Table 1. Demographics and baseline variables in patients with non-surgical gastroparesis were not significantly different in the 2 treatment groups</b>

Table 1. Demographics and baseline variables in patients with non-surgical gastroparesis were not significantly different in the 2 treatment groups

<b>Table 2. Effects of cannabidiol and placebo treatment in non-surgical gastroparesis</b>

Table 2. Effects of cannabidiol and placebo treatment in non-surgical gastroparesis

Introduction: G-POEM has been demonstrated to enhance the QOL in GP patients, however, there is limited evidence to support its long-term benefits on the QOL of affected patients. Aim: Determine the effect of G-POEM on QOL in patients with GP up to 48 months of follow-up.

Methods: In this prospective single institution cohort study, patients who had their GP confirmed by a 4-hour solid-phase stomach emptying scan within a year of their G-POEM procedure were enrolled. G-POEM procedures were performed between February 2018 and October 2022 by 2 expert third space endoscopists. All patients underwent study evaluations per protocol at baseline and then at 1, 3, 6, 12, 24, 36, and 48 months post G-POEM. The Gastroparesis Cardinal Symptom Index (GCSI), the Patient Assessment of Gastrointestinal Disorders Symptom Severity Index (PAGI-SYM), and the 36-Item Short Form Survey Instrument (SF-36) were used as validated symptom and QOL tools. In addition, hospitalization utilization data were collected about days of home health care, frequency of emergency room visits, and days hospitalized at baseline, 6, 12, 24, 36, and 48 months after G-POEM. Clinical success of G-POEM was defined as improvement in total GCSI score by at least 1 point.

Results: 96 patients (median age: 49 years, range 25-86, 89% female) underwent G-POEM for diabetic (n=34), idiopathic (n=42), and post-surgical (n=20) GP. GP clinical phenotypes included: regurgitation predominant (n=19), dyspepsia predominant (n = 35), and vomiting predominant (n = 42). GCSI score significantly improved from baseline of 3.3 ± 1.0 to 2.4 ± 1.4 at 24 months post G-POEM (Table 1). Additionally, significant improvements in several SF-36 domains were noted for up to 36-months (Fig. 1). The SF-36 total score significantly increased to 64.6 ± 22.7 at 36-months compared to 41.6 ± 18.2 at baseline (p=0.039). At 48-months, Nausea/Vomiting subscore significantly improved to 1.6 ± 1.2 compared to 3.0 ± 1.4 at baseline (p= 0.018). At 12-months, clinical success was observed in 22/45 (49%) of patients. At 24-, 36-, and 48-months, clinical success was observed in 38%, 42%, and 40% respectively. At 36-months, the average number of emergency room visits over the previous 6 months for GP related symptoms had significantly decreased to 0.0 ± 0.0 compared to 2.1 ± 3.8 at baseline (p = 0.024) (Table 1).

Conclusion: Despite the declining clinical success rates (by GCSI definition) over time, G-POEM continued to positively impact symptom severity, QoL, and healthcare utilization by reducing the number of emergency room visits in our study for up to three years. To confirm our findings and guide patient selection, a larger cohort of patients should be studied.

Figure 1: Demonstration of the calculated average scores of PAGI-SYM, GCSI, and various sub-categories for patients who underwent G-POEM for gastroparesis.<br /> <br /> 95% confidence intervals are included as well.

Figure 1: Demonstration of the calculated average scores of PAGI-SYM, GCSI, and various sub-categories for patients who underwent G-POEM for gastroparesis.

95% confidence intervals are included as well.

Table 1: Results of SF-36 QOL, PAGI-SYM, and GCSI (mean ± SD) before and after G-POEM in patients with GP.<br /> <br /> *p < 0.05 as compared to baseline. **Range from 0 to 100; <sup>+</sup>Range from 0 to 5.

Table 1: Results of SF-36 QOL, PAGI-SYM, and GCSI (mean ± SD) before and after G-POEM in patients with GP.

*p < 0.05 as compared to baseline. **Range from 0 to 100; ⁺Range from 0 to 5.

BACKGROUND & AIMS: Impaired gastric motor dysfunction in the elderly causes reduced food intake leading to frailty, immobility, sarcopenia and weight loss. Aging-related reduced gastric compliance was mainly due to depletion of interstitial cells of Cajal (ICC) (PMID: 32771388), pacemaker and neuromodulator cells. These changes were associated with reduced food intake. Transformation related protein 53 (Trp53)-induced suppression of extracellular signaling-regulated protein kinase (ERK)1/2 in ICC stem cells (ICC-SC) cell cycle arrest is a key process for ICC depletion and gastric dysfunction with age. The multifunctional polypeptide hormone insulin-like growth factor1 (IGF1) can activate ERK in gastric smooth muscles (PMID: 24116170) and is reduced in klotho mice (PMID: 9363890), a model of accelerated aging. Here, we investigated whether IGF1 could mitigate ICC-SC/ICC loss and gastric motor dysfunction in klotho mice. METHODS: Gastric muscles from patients between 26 and 82 years of age were studied by western immunoblotting (WB). klotho mice were treated with the stable IGF1 analog LONG R³ recombinant human (rh) IGF1 (150 µg/kg i.p. BID for 3 weeks) when the mice were 6-7 weeks old; i.e., at the time when klotho mice begin to display a wide array of premature aging phenotypes. Gastric ICC/ICC-SC were studied by flow cytometry, WB and immunohistochemistry. Cell cycle analysis of ICC-SC was studied by flow cytometry. Gastric motor function was assessed in ex vivo gastric compliance assays. Trp53 was induced with nutlin 3a and ERK1/2 signaling was activated by rhIGF-1 in the gastric muscle organotypic culture systems and the ICC-SC line (PMID: 20621681). RESULTS: In human, gastric IGF1 protein gradually decreased with age and this reduction was associated with the reduction of ICC markers and ERK1/2 phosphorylation, suggesting that reduced ERK phosphorylation due to reduced IGF1 likely contributes to ICC decline. LONG R³ rhIGF1 treatment prevented reduced ERK1/2 phosphorylation and gastric ICC/ICC-SC decline. The effect of IGF1 was corroborated by gastric muscle organotypic culture systems. rhIGF1 restored nutlin 3a-induced reduction in ERK phosphorylation and ICC-SC growth arrest. LONG R³ rhIGF1 also mitigated the reduced food intake, impaired body weight gain and reduced gastric compliance of klotho mice. Surprisingly, the same treatment significantly extended lifespan of klotho mice (Kaplan-Meier Log-rank P=0.0013). In ICC-SC cultures, rhIGF1 mitigated nutlin 3a-induced reduced ERK1/2 phosphorylation and G₂/M cell cycle arrest. CONCLUSIONS: Gastric IGF1 is reduced with age and IGF1 can mitigate age-related ICC/ICC-SC loss by activating ERK1/2 signaling leading to improved gastric compliance, food intake, body weight gain and survival of klotho mice. Grant support: NIH R01 DK121766, P30 DK084567, AGA-Allergan Foundation

Egan Choi

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DECLINE IN GASTRIC INSULIN-LIKE GROWTH FACTOR1 INITIATES GASTRIC PACEMAKER CELL AGING

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