A pilot genome-wide association study meta-analysis of gastroparesis.

BACKGROUND: Gastroparesis (GP) is characterized by delayed gastric emptying in the absence of mechanical obstruction. OBJECTIVE: Genetic predisposition may play a role; however, investigation at the genome-wide level has not been performed. METHODS: We carried out a genome-wide association study (GWAS) meta-analysis on (i) 478 GP patients from the National Institute of Diabetes and Digestive and Kidney Diseases Gastroparesis Clinical Research Consortium (GpCRC) compared to 9931 population-based controls from the University of Michigan Health and Retirement Study; and (ii) 402 GP cases compared to 48,340 non-gastroparesis controls from the Michigan Genomics Initiative. Associations for 5,811,784 high-quality SNPs were tested on a total of 880 GP patients and 58,271 controls, using logistic mixed models adjusted for age, sex, and principal components. Gene mapping was obtained based on genomic position and expression quantitative trait loci, and a gene-set network enrichment analysis was performed. Genetic associations with clinical data were tested in GpCRC patients. Protein expression of selected candidate genes was determined in full thickness gastric biopsies from GpCRC patients and controls. RESULTS: While no SNP associations were detected at strict significance (p ≤ 5 × 10-8 ), nine independent genomic loci were associated at suggestive significance (p ≤ 1 × 10-5 ), with the strongest signal (rs9273363, odds ratio = 1.4, p = 1 × 10-7 ) mapped to the human leukocyte antigen region. Computational annotation of suggestive risk loci identified 14 protein-coding candidate genes. Gene-set network enrichment analysis revealed pathways potentially involved in immune and motor dysregulation (pFDR ≤ 0.05). The GP risk allele rs6984536A (Peroxidasin-Like; PXDNL) was associated with increased abdominal pain severity scores (Beta = 0.13, p = 0.03). Gastric muscularis expression of PXDNL also positively correlated with abdominal pain in GP patients (r = 0.8, p = 0.02). Dickkopf WNT Signaling Pathway Inhibitor 1 showed decreased expression in diabetic GP patients (p = 0.005 vs. controls). CONCLUSION: We report preliminary GWAS findings for GP, which highlight candidate genes and pathways related to immune and sensory-motor dysregulation. Larger studies are needed to validate and expand these findings in independent datasets.

Hypoxia-Inducible Factor 1α Stabilization Restores Epigenetic Control of Nitric Oxide Synthase 1 Expression and Reverses Gastroparesis in Female Diabetic Mice.

BACKGROUND & AIMS: Although depletion of neuronal nitric oxide synthase (NOS1)-expressing neurons contributes to gastroparesis, stimulating nitrergic signaling is not an effective therapy. We investigated whether hypoxia-inducible factor 1α (HIF1A), which is activated by high O2 consumption in central neurons, is a Nos1 transcription factor in enteric neurons and whether stabilizing HIF1A reverses gastroparesis. METHODS: Mice with streptozotocin-induced diabetes, human and mouse tissues, NOS1+ mouse neuroblastoma cells, and isolated nitrergic neurons were studied. Gastric emptying of solids and volumes were determined by breath test and single-photon emission computed tomography, respectively. Gene expression was analyzed by RNA-sequencing, microarrays, immunoblotting, and immunofluorescence. Epigenetic assays included chromatin immunoprecipitation sequencing (13 targets), chromosome conformation capture sequencing, and reporter assays. Mechanistic studies used Cre-mediated recombination, RNA interference, and clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9)-mediated epigenome editing. RESULTS: HIF1A signaling from physiological intracellular hypoxia was active in mouse and human NOS1+ myenteric neurons but reduced in diabetes. Deleting Hif1a in Nos1-expressing neurons reduced NOS1 protein by 50% to 92% and delayed gastric emptying of solids in female but not male mice. Stabilizing HIF1A with roxadustat (FG-4592), which is approved for human use, restored NOS1 and reversed gastroparesis in female diabetic mice. In nitrergic neurons, HIF1A up-regulated Nos1 transcription by binding and activating proximal and distal cis-regulatory elements, including newly discovered super-enhancers, facilitating RNA polymerase loading and pause-release, and by recruiting cohesin to loop anchors to alter chromosome topology. CONCLUSIONS: Pharmacologic HIF1A stabilization is a novel, translatable approach to restoring nitrergic signaling and treating diabetic gastroparesis. The newly recognized effects of HIF1A on chromosome topology may provide insights into physioxia- and ischemia-related organ function.

Enrichment of Patients With Ehlers Danlos Syndrome in Idiopathic Gastroparesis-A Gene Set Enrichment Analysis.

INTRODUCTION: Ehlers Danlos syndrome (EDS) is a heritable disorder of the connective tissue usually inherited as an autosomal dominant trait. We observe an enrichment of EDS cases in a gastroparesis clinical study. METHODS: We explored the frequency of EDS cases in 2 consecutive gastroparesis clinical studies. To explore the genetic surrogates of EDS, we have performed whole-genome sequencing analysis and we focused the analyses on the frequencies of consequential variants in core EDS genes. RESULTS: We report a significant enrichment of EDS cases in a set of patients with gastroparesis (14/686 vs 1/5,000 OR 104 (confidence interval 13.7-793.3) P value <0.0001). We report a significant enrichment of variants in EDS genes in patients with idiopathic gastroparesis. DISCUSSION: The enrichment may be suggestive of converging pathways at the heart of etiology or predisposing patients to EDS with gastroparesis.

[Electroacupuncture promotes gastrointestinal motility by activating autophagy of Cajal interstitial cells via downregulating PI3K/Akt/mTOR signaling pathway in stomach of diabetic gastro-paresis rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) of "Zusanli" (ST36), "Sanyinjiao" (SP6) and "Liangmen" (ST21) on gastrointestinal motility, blood glucose content and expression of autophagy-related proteins 1 light chain 3 (LC3), p62, phosphatidyli-nositol-3 kinase (PI3K), protein kinase B (Akt), p-Akt and mammalian target protein of rapamycin (mTOR) of interstitial cells of Cajal (ICCs) in the cultured gastric antrum cells in diabetic gastroparesis (DGP) rats, so as to reveal its mechanisms underlying improvement of DGP. METHODS: A total of 45 Sprague Dawley (SD) rats were randomly divided into blank control, model, EA, medication (3-methyladenine, 3-MA) and EA+3-MA groups, with 9 rats in each group. The DGP model was established by intraperitoneal injection of 2% streptozotocin (STZ) combined with high-fat and high sugar diet for 8 weeks. The gastric emptying rate was measured by using gavage of phenol red (to measure the propelling length of the phenol red/total length of small intestine ×100%). The symptom score (mental state, coat color and luster, behavior and activity, stool traits) of rats was observed every week and the blood glucose content was measured by using a glucometer. EA (20 Hz/100 Hz, 2 mA) was applied to unilateral ST36, SP6 and ST21 alternatively for 15 min, once daily, 5 days a week for 3 weeks. Rats of the 3-MA and 3-MA+EA groups received intraperitoneal injection of 3-MA (30 mg·kg-1·d-1, 10 mg/mL), once daily, 5 days a week for 3 weeks. After 15 days' intervention, the rats were operated for gastric emptying rate test, specimen collection, isolation, and culture of primary ICCs. The expression levels of microtubule associated protein LC3, p62, PI3K, Akt, p-Akt and mTOR of ICCs of cultured gastric antrum cells were detected using Western blot, and the number of autophagosomes in ICC of gastric antrum was observed under transmission electron microscope. RESULTS: Compared with the blank control group, the symptom score, blood glucose, and the expression levels of p62, class Ⅰ PI3K, Akt, p-Akt and mTOR proteins were increased significantly (P<0.01), while the gastric emptying rate and ratio of LC3Ⅱ/LC3Ⅰ and the expression level of class Ⅲ PI3K protein were significantly decreased (P<0.05, P<0.01) in the model group. In comparison with the model group, the increase of symptom score, blood glucose, and expression levels of p62, class Ⅰ PI3K, Akt, p-Akt and mTOR proteins and the decrease of gastric empty rate and LC3Ⅱ/LC3Ⅰ ratio and the expression level of class Ⅲ PI3K protein were all reversed in both EA and EA+3-MA groups (P<0.05, P<0.01), rather than in the 3-MA group. In addition, 3-MA also reversed modeling-induced increase of class Ⅰ PI3K, Akt, p-Akt and mTOR proteins expression (P<0.01). No significant differences were found between the EA and EA+3-MA in downregulating the levels of symptom score and blood glucose content, and in upregulating gastric empty rate(P>0.05). The effect of EA was notably superior to that of EA+3-MA in upregulating the ratio of LC3Ⅱ/LC3Ⅰ and the expression level of class Ⅲ PI3K protein, and in downregulating the expression of p62, class Ⅰ PI3K, Akt, p-Akt and mTOR proteins (P<0.05, P<0.01). The findings of transmission electron microscopy showed obvious swelling, breakage of some mitochondrial cristae in the ICC cells of antrum and no autophagosomes in the model group and 3-MA group, which was milder in the damage of mitochondrial cristae and marked increase in the autophagosomes in both EA and EA+3-MA groups. CONCLUSION: EA can improve the gastrointestinal motility and symptoms in DGP rats, which may be related to its functions in downregulating PI3K/Akt/mTOR signaling to promote autophagy level of ICC.

[Effect of electroacupuncture combined with Zhuang-medicine-thread moxibustion on expression of apoptosis-related factors in gastric antrum of diabetic gastroparesis rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) combined with Zhuang-medicine-thread moxibustion on expression of apoptosis-related factors in gastric antrum of diabetic gastroparesis (DGP) rats, so as to explore its mechanism underlying improvement of DGP. METHODS: Male SD rats were randomly divided into normal, model, medication, EA, Zhuang-medicine-thread moxibustion (moxibustion) and EA+moxibustion (combination) groups (12 rats in each group). The DGP model was established by intraperitoneal injection of streptozotocin (STZ). Rats of the medication group were treated by gavage of 0.15 mg/mL mosapride citrate suspension （10 mL/kg）. EA (10 Hz/50 Hz, 2 mA, 20 min) or Zhuang-medicine-thread moxibustion (3 cones) was applied to "Zhongwan" (CV12), bilateral "Neiguan" (PC6) and bilateral "Sanyinjiao" (SP6) of the related groups, once a day for 3 weeks. The blood glucose, gastric emptying rate and intestinal propulsion rate of rats were measured. The apoptosis index of gastric antrum cells were observed by TUNEL staining. The protein and mRNA expressions of Caspase-3, B-cell lymphoma/leukemia-2 (Bcl-2) and Bcl-2 associated X protein (Bax) in gastric antrum were detected by Wes-tern blot and real-time quantitative PCR, respectively. RESULTS: Compared with the normal group, the blood glucose, the apoptosis index, the protein and gene expressions of Caspase-3 and Bax were significantly increased (P<0.01), and the gastric emptying rate, intestinal propulsive rate, the protein and gene expressions of Bcl-2 were considerably decreased (P<0.01) in the model group. In contrast to the model group, the blood glucose in the EA, moxibustion and combination groups, the apoptosis index in the 4 treatment groups, as well as Caspase-3 protein, Bax protein and mRNA expressions in the medication, EA and combination groups, Caspase-3 protein and mRNA, Bax mRNA expressions in the moxibustion group were significantly decreased (P<0.01, P<0.05); while the gastric emptying rate and intestinal propulsive rate in the 4 treatment groups, and Bcl-2 protein and mRNA expressions in the medication and combination groups, Bcl-2 mRNA expressions in the EA and moxibustion groups were obviously increased (P<0.01). The effects of EA+moxibustion were significantly superior to those of simple EA, moxibustion or medication in increasing gastric emptying rate and intestinal propulsive rate, and in lowering blood glucose (P<0.05, P<0.01). And the effects of the combination treatment were better than those of EA in lowering Caspase-3 protein and Bax mRNA expressions (P<0.01), and in increasing Bcl-2 protein and mRNA expressions (P<0.05, P<0.01). Also the effects of the combination treatment were better than those of moxibustion in lowering the apoptosis index, Caspase-3 protein, and Bax protein and mRNA expressions (P<0.01, P<0.05), and in increasing Bcl-2 protein expression (P<0.05). CONCLUSION: EA combined with Zhuang-medicine-thread moxibustion can reduce blood glucose and improve gastrointestinal motility in DGP rats, which may be related to its effect in regulating of Caspase-3, Bax and Bcl-2 expression.

Enrichment of Motilin Receptor Loss-of-Function Variants in Gastroparesis.

INTRODUCTION: Gastroparesis is a serious medical condition characterized by delayed gastric emptying and symptoms of nausea, vomiting, bloating, fullness after meals, and abdominal pain. METHODS: To ascertain the genetic risk factors for gastroparesis, we conducted the largest thus far whole-genome sequencing study of gastroparesis. We investigated the frequency and effect of rare loss-of-function variants in patients with both idiopathic and diabetic gastroparesis enrolled in a clinical study of gastroparesis. RESULTS: Among rare loss-of-function variants, we reported an increased frequency of a frameshift mutation p.Leu202ArgfsTer105, within the motilin receptor gene, variant rs562138828 (odds ratio 4.9). We currently replicated this finding in an independent large cohort of gastroparesis samples obtained from patients participating in the ongoing phase III gastroparesis clinical study. DISCUSSION: Motilin receptor is an important therapeutic target for the treatment of hypomotility disorders. The identified genetic variants may be important risk factors for disease as well as may inform treatments, especially those targeting motilin receptor.

[Effect of electroacupuncture combined with Zhuang-medicine-thread moxibustion on silent information regulator-1/nuclear factor κB signaling pathway in gastric antrum of diabetic gastroparesis rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) combined with Zhuang-medicine-thread moxibustion on silent information regulator-1 (SIRT1)/nuclear factor kappa B (NF-κB) signal pathway and inflammatory factor expression in gastric antrum tissue of diabetic gastroparesis (DGP) rats, so as to explore its mechanism underlying improvement of DGP. METHODS: Male SD rats were randomly divided into normal, model, medication, EA, Zhuang-medicine-thread moxibustion (moxibustion) and EA+moxibustion groups (n=12 per group). The DGP model was established by intraperitoneal injection of streptozotocin (STZ). Rats of the medication group were treated by gavage of 0.15 mg/mL mosapride citrate suspension. EA (10 Hz /50 Hz, 2 mA) or moxibustion (3 cones) or EA+moxibustion was applied to "Zhongwan"(CV12), bilateral "Neiguan"(PC6) and bilateral "Sanyinjiao"(SP6) of the related group for 20 min, once a day for 3 weeks. Blood glucose, gastric emptying rate and intestinal propulsion rate were measured. The levels of serum interleukin (IL)-6, IL-8, IL-10 and tumor necrosis factor-α(TNF-α) were detected by ELISA; the phosphorylation level of the phosphorylated inhibitor of nuclear factor κBα inhibitor (pIκ-Bα), the protein and mRNA expression of NF-κB p65 and SIRT1 in the gastric antrum tissue were detected by Western blot and real-time quantifitative PCR, respectively. RESULTS: (1) Compared with the normal group, the levels of blood glucose, serum IL-6, IL-8, TNF-α, and gastric pIκ-Bα and NF-κB p65 protein and mRNA expressions were significantly increased (P<0.01), and the gastric emptying rate, intestinal propulsion rate, serum IL-10 level, and SIRT1 protein and mRNA expressions were considerably decreased in the model group (P<0.01). (2) In contrast to the model group, the blood glucose in the EA, moxibustion and EA+moxibustion groups, serum IL-6, IL-8 and TNF-α levels in the 4 treatment groups, as well as NF-κB p65 protein expression in the medication and EA+moxibustion groups, and NF-κB p65 mRNA expression and pIκ-Bα protein and mRNA expression in the 4 treatment groups were significantly decreased (P<0.01, P<0.05); while the gastric emptying rate and intestinal propulsive rate and IL-10 content in the 4 treatment groups, and SIRT1 protein and mRNA expression in the medication and EA+moxibustion groups were obviously increased (P<0.05, P<0.01). (3) The effects of EA+moxibustion were significantly superior to those of simple EA and moxibustion in increasing gastric emptying rate, IL-10, SIRT1 protein expression (P<0.05, P<0.01), and in lowering IL-8 and TNF-α contents, pIκ-Bα protein and mRNA expression and NF-κB p65 mRNA expression (P<0.05, P<0.01). No significant differences were found among the 4 intervention groups in promoting the intestinal propulsive rate and among the EA, moxibustion and EA+moxibustion groups in lowering blood glucose (P>0.05). CONCLUSION: EA combined with Zhuang-medicine-thread moxibustion can effectively reduce the level of serum inflammatory factors and regulate SIRT1/NF-κB signal pathway in DGP rats, which may contribute to its function in improving gastrointestinal movement.

miR-10b-5p Rescues Diabetes and Gastrointestinal Dysmotility.

BACKGROUND & AIMS: Interstitial cells of Cajal (ICCs) and pancreatic ß cells require receptor tyrosine kinase (KIT) to develop and function properly. Degeneration of ICCs is linked to diabetic gastroparesis. The mechanisms linking diabetes and gastroparesis are unclear, but may involve microRNA (miRNA)-mediated post-transcriptional gene silencing in KIT+ cells. METHODS: We performed miRNA-sequencing analysis from isolated ICCs in diabetic mice and plasma from patients with idiopathic and diabetic gastroparesis. miR-10b-5p target genes were identified and validated in mouse and human cell lines. For loss-of-function studies, we used KIT+ cell-restricted mir-10b knockout mice and KIT+ cell depletion mice. For gain-of-function studies, a synthetic miR-10b-5p mimic was injected in multiple diabetic mouse models. We compared the efficacy of miR-10b-5p mimic treatment vs antidiabetic and prokinetic medicines. RESULTS: miR-10b-5p is highly expressed in ICCs from healthy mice, but drastically depleted in ICCs from diabetic mice. A conditional knockout of mir-10b in KIT+ cells or depletion of KIT+ cells in mice leads to degeneration of ß cells and ICCs, resulting in diabetes and gastroparesis. miR-10b-5p targets the transcription factor Krüppel-like factor 11 (KLF11), which negatively regulates KIT expression. The miR-10b-5p mimic or Klf11 small interfering RNAs injected into mir-10b knockout mice, diet-induced diabetic mice, and TALLYHO polygenic diabetic mice rescue the diabetes and gastroparesis phenotype for an extended period of time. Furthermore, the miR-10b-5p mimic is more effective in improving glucose homoeostasis and gastrointestinal motility compared with common antidiabetic and prokinetic medications. CONCLUSIONS: miR-10b-5p is a key regulator in diabetes and gastrointestinal dysmotility via the KLF11-KIT pathway. Restoration of miR-10b-5p may provide therapeutic benefits for these disorders.

Duodenal mucosal mitochondrial gene expression is associated with delayed gastric emptying in diabetic gastroenteropathy.

Hindered by a limited understanding of the mechanisms responsible for diabetic gastroenteropathy (DGE), management is symptomatic. We investigated the duodenal mucosal expression of protein-coding genes and microRNAs (miRNA) in DGE and related them to clinical features. The diabetic phenotype, gastric emptying, mRNA, and miRNA expression and ultrastructure of duodenal mucosal biopsies were compared in 39 DGE patients and 21 controls. Among 3175 differentially expressed genes (FDR < 0.05), several mitochondrial DNA-encoded (mtDNA-encoded) genes (12 of 13 protein coding genes involved in oxidative phosphorylation [OXPHOS], both rRNAs and 9 of 22 transfer RNAs) were downregulated; conversely, nuclear DNA-encoded (nDNA-encoded) mitochondrial genes (OXPHOS) were upregulated in DGE. The promoters of differentially expressed genes were enriched in motifs for transcription factors (e.g., NRF1), which regulate mitochondrial biogenesis. Seventeen of 30 differentially expressed miRNAs targeted differentially expressed mitochondrial genes. Mitochondrial density was reduced and correlated with expression of 9 mtDNA OXPHOS genes. Uncovered by principal component (PC) analysis of 70 OXPHOS genes, PC1 was associated with neuropathy (P = 0.01) and delayed gastric emptying (P < 0.05). In DGE, mtDNA- and nDNA-encoded mitochondrial genes are reduced and increased - associated with reduced mitochondrial density, neuropathy, and delayed gastric emptying - and correlated with cognate miRNAs. These findings suggest that mitochondrial disturbances may contribute to delayed gastric emptying in DGE.

Study on the Mechanisms of Banxia Xiexin Decoction in Treating Diabetic Gastroparesis Based on Network Pharmacology.

In China, Banxia Xiexin decoction (BXD) is applied to treat diabetic gastroparesis (DGP), but its key active ingredients and mechanisms against DGP are unclear. This study is designated to reveal the molecular mechanisms of BXD in treating DGP by adopting a creative approach known as network pharmacology to explore the active ingredients and therapeutic targets of BXD. In our study, 730 differentially expressed genes of DGP were obtained, and 30 potential targets of BXD against DGP were screened out (including ADRB2, DRD1, FOS, MMP9, FOSL1, FOSL2, JUN, MAP2, DRD2, MYC, F3, CDKN1A, IL6, NFKBIA, ICAM1, CCL2, SELE, DUOX2, MGAM, THBD, SERPINE1, ALOX5, CXCL11, CXCL2, CXCL10, RUNX2, CD40LG, C1QB, MCL1, and ADCYAP1). Based on the findings, BXD contains 60 compounds with therapeutic effect on DGP, including the key active ingredients such as quercetin, wogonin, baicalein, beta-sitosterol, and kaempferol. Sixty-eight pathways including TNF signaling pathway, IL-17 signaling pathway, and AGE-RAGE signaling pathway were significantly enriched. In this study, the mechanisms of BXD in treating DGP are affirmed to be a complex network with multi-target and multi-pathway, which provides a reference for future experimental studies.

Protein-elongating mutations in MYH11 are implicated in a dominantly inherited smooth muscle dysmotility syndrome with severe esophageal, gastric, and intestinal disease.

Gastrointestinal motility disorders include a spectrum of mild to severe clinical phenotypes that are caused by smooth muscle dysfunction. We investigated the genetic etiology of severe esophageal, gastric, and colonic dysmotility in two unrelated families with autosomal dominant disease presentation. Using exome sequencing, we identified a 2 base pair insertion at the end of the myosin heavy chain 11 (MYH11) gene in all affected members of Family 1 [NM_001040113:c.5819_5820insCA(p.Gln1941Asnfs*91)] and a 1 base pair deletion at the same genetic locus in Proband 2 [NM_001040113:c.5819del(p.Pro1940Hisfs*91)]. Both variants are predicted to result in a similarly elongated protein product. Heterozygous dominant negative MYH11 pathogenic variants have been associated with thoracic aortic aneurysm and dissection while biallelic null alleles have been associated with megacystis microcolon intestinal hypoperistalsis syndrome. This report highlights heterozygous protein-elongating MYH11 variants affecting the SM2 isoforms of MYH11 as a cause for severe gastrointestinal dysmotility, and we hypothesize that the mechanistic pathogenesis of this disease, dominant hypercontractile loss-of-function, is distinct from those implicated in other diseases involving MYH11 dysfunction.

Proteomics in gastroparesis: unique and overlapping protein signatures in diabetic and idiopathic gastroparesis.

Macrophage-based immune dysregulation plays a critical role in development of delayed gastric emptying in diabetic mice. Loss of anti-inflammatory macrophages and increased expression of genes associated with pro-inflammatory macrophages has been reported in full-thickness gastric biopsies from gastroparesis patients. We aimed to determine broader protein expression (proteomics) and protein-based signaling pathways in gastric biopsies of diabetic (DG) and idiopathic gastroparesis (IG) patients. Additionally, we determined correlations between protein expressions, gastric emptying, and symptoms. Full-thickness gastric antrum biopsies were obtained from nine DG patients, seven IG patients, and five nondiabetic controls. Aptamer-based SomaLogic tissue scan that quantitatively identifies 1,305 human proteins was used. Protein fold changes were computed, and differential expressions were calculated using Limma. Ingenuity pathway analysis and correlations were carried out. Multiple-testing corrected P < 0.05 was considered statistically significant. Seventy-three proteins were differentially expressed in DG, 132 proteins were differentially expressed in IG, and 40 proteins were common to DG and IG. In both DG and IG, "Role of Macrophages, Fibroblasts and Endothelial Cells" was the most statistically significant altered pathway [DG false discovery rate (FDR) = 7.9 × 10-9; IG FDR = 6.3 × 10-12]. In DG, properdin expression correlated with GCSI bloating (r = -0.99, FDR = 0.02) and expressions of prostaglandin G/H synthase 2, protein kinase C-ζ type, and complement C2 correlated with 4 h gastric retention (r = -0.97, FDR = 0.03 for all). No correlations were found between proteins and symptoms or gastric emptying in IG. Protein expression changes suggest a central role of macrophage-driven immune dysregulation in gastroparesis, specifically, complement activation in diabetic gastroparesis.NEW & NOTEWORTHY This study uses SOMAscan, a novel proteomics assay for determination of altered proteins and associated molecular pathways in human gastroparesis. Seventy-three proteins were changed in diabetic gastroparesis, 132 in idiopathic gastroparesis compared with controls. Forty proteins were common in both. Macrophage-based immune dysregulation pathway was most significantly affected in both diabetic and idiopathic gastroparesis. Proteins involved in the complement and prostaglandin synthesis pathway were associated with symptoms and gastric emptying delay in diabetic gastroparesis.

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.

Activation of Nrf2 attenuates delayed gastric emptying in obesity induced diabetic (T2DM) female mice.

Diabetic gastroparesis (GP) is a clinical syndrome characterized by delayed gastric emptying (DGE). Loss of Nrf2 (Nuclear factor (erythroid-derived 2)-like 2) led to reduced nNOSα mediated gastric motility and DGE. The molecular signaling of cinnamaldehyde (CNM) mediated Nrf2 activation and its mechanistic role on DGE were further investigated in obese/T2D female mice. Adult female homozygous Nfe2l2-/- (C57BL/6J) and their wild-type (WT) littermates (Nfe2l2+/+) mice were fed with high fat diet (HFD; Obese/T2D model), or normal diet (ND) with or without CNM (50 mg/kg b.w; i.p). Supplementation of CNM attenuated (p < 0.05) DGE in WT female but not in Nrf2 KO Obese/T2D mice. CNM (1) normalized serum estradiol-17ß levels, (2) induced gastric Nrf2 and phase II antioxidant enzymes through extracellular signal-regulated kinase, (ERK)/c-Jun N-terminal kinase (JNK)/p38 mitogen-activated protein kinase (MAPK), (3) reduced glucose synthase kinase 3 beta (GSK3ß) and aryl hydrocarbon receptor (AhR) and this was associated with (4) increased estrogen receptor expression, BH4 (Cofactor of nNOS) biosynthesis enzyme GCH-1 and nNOSα dimerization in WT Obese/T2 diabetic female mice. In addition, CNM restored impaired nitrergic relaxation in hyperglycemic conditions. These findings emphasize the importance of Nrf2 in maintaining nNOSα mediated GE and may have a translational relevance to treat obese/diabetic gastroparesis in women.

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.

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.

LncRNA MALAT1 is up-regulated in diabetic gastroparesis and involved in high-glucose-induced cellular processes in human gastric smooth muscle cells.

Recent years, widespread long non-coding RNAs (lncRNAs) were identified and known as regulator of gene expression. Diabetic gastroparesis (DGP) is one of the most common chronic complications of diabetes mellitus. There was no research reported the role of lncRNAs in DGP. In this study, we firstly established a rat model of DGP by STZ injection. Then, we detected the expression of MALAT1 and found that expression of MALAT1 was up-regulated in rat model of DGP, comparing to the control group (P < .01). Furthermore, we revealed that MALAT1 expression was increased in the samples from diabetic patients with DGP symptoms, in comparison with the control. In addition, we demonstrated that the inhibition of MALAT1 increased the expression of α-SMA and SM myosin heavy chains, reduced the cell viability, inhibited the potential of cell migration and induced cell apoptosis in human gastric smooth muscle cells (SMCs). Ultimately, we found that the regulation of MALAT1 expression modulated the function of high-glucose stimulation in human gastric SMCs. Therefore, our study firstly indicated that MALAT1 was up-regulated in DGP and played an important role in the pathogenesis of DGP.

Repeat polymorphisms in the Homo sapiens heme oxygenase-1 gene in diabetic and idiopathic gastroparesis.

BACKGROUND: Idiopathic and diabetic gastroparesis in Homo sapiens cause significant morbidity. Etiology or risk factors have not been clearly identified. Failure to sustain elevated heme oxygenase-1 (HO1) expression is associated with delayed gastric emptying in diabetic mice and polymorphisms in the HO1 gene (HMOX1, NCBI Gene ID:3162) are associated with worse outcomes in other diseases. AIM: Our hypothesis was that longer polyGT alleles are more common in the HMOX1 genes of individuals with gastroparesis than in controls without upper gastrointestinal motility disorders. METHODS: Repeat length was determined in genomic DNA. Controls with diabetes (84 type 1, 84 type 2) and without diabetes (n = 170) were compared to diabetic gastroparetics (99 type 1, 72 type 2) and idiopathic gastroparetics (n = 234). Correlations of repeat lengths with clinical symptom sub-scores on the gastroparesis cardinal symptom index (GCSI) were done. Statistical analyses of short (<29), medium and long (>32) repeat alleles and differences in allele length were used to test for associations with gastroparesis. RESULTS: The distribution of allele lengths was different between groups (P = 0.016). Allele lengths were longest in type 2 diabetics with gastroparesis (29.18±0.35, mean ± SEM) and longer in gastroparetics compared to non-diabetic controls (28.50±0.14 vs 27.64±0.20 GT repeats/allele, P = 0.0008). Type 2 diabetic controls had longer alleles than non-diabetic controls. In all gastroparetic groups, allele lengths were longer in African Americans compared to other racial groups, differences in the proportion of African Americans in the groups accounted for the differences between gastroparetics and controls. Diabetic gastroparetics with 1 or 2 long alleles had worse GCSI nausea sub-scores (3.30±0.23) as compared to those with 0 long alleles (2.66±0.12), P = 0.022. CONCLUSIONS: Longer poly-GT repeats in the HMOX1 gene are more common in African Americans with gastroparesis. Nausea symptoms are worse in subjects with longer alleles.

Impaired insulin/IGF-1 is responsible for diabetic gastroparesis by damaging myenteric cholinergic neurones and interstitial cells of Cajal.

Diabetic gastroparesis is a common complication of diabetes mellitus (DM) that is characterized by decreased serum insulin and insulin-like growth factor-1 (IGF-1). Despite the fact that insulin treatment not glycemic control potently accelerated gastric emptying in type 1 DM patients, the role of insulin/InsR and IGF-1/IGF-1R signaling in diabetic gastroparesis remains incompletely elucidated. In the present study, type 1 DM mice were established and treated with insulin or Voglibose for 8 weeks. The gastric emptying was delayed from DM week 4 when the gastric InsR and IGF-1R were declined. Meanwhile, the gastric choline acetyltransferase (ChAT) was significantly reduced and the myenteric cholinergic neurones and their fibers were significantly diminished. The production of stem cell factor (SCF) was dramatically repressed in the gastric smooth muscles in DM week 6. TWereafter, interstitial cells of Cajal (ICC) were clearly lost and their networks were impaired in DM week 8. Significantly, compared with Voglibose, an 8-week treatment with insulin more efficiently delayed diabetic gastroparesis development by protecting the myenteric cholinergic neurones and ICC. In conclusion, diabetic gastroparesis was an aggressive process due to the successive damages of myenteric cholinergic neurones and ICC by impairing the insulin/InsR and IGF-1/IGF-1R signaling. Insulin therapy in the early stage may delay diabetic gastroparesis.

Delayed gastric emptying in diabetic rats caused by decreased expression of cystathionine gamma lyase and H2 S synthesis: in vitro and in vivo studies.

BACKGROUND: This study aimed to evaluate the role of H2 S on gastric emptying rate (GER) and also to determine the effect of gastric distention on mRNA and protein expression of cystathionine ß-lyase (CBS) and cystathionine γ-synthase (CSE) in diabetic-gastroparetic and normal rats. METHODS: Adult normal rats intraperitoneally received either propargylglycine (PAG), L-cysteine or NaHS 30 min prior to GER marker (acetaminophen) to investigate H2 S involvement in GER and the same protocols were performed in diabetes-induced gastroparesis rats. The role of calcitonin gene related peptide (CGRP) neurons in the prokinetic effect of endogenous H2 S on GER was determined. The level of CBS and CSE expressions in response to gastric distention were also determined. The effect of H2 S on frequency and tension of spontaneous contractions of gastric smooth muscle strips was investigated. KEY RESULTS: Our results showed that: (i) H2 S and L-cysteine increased GER in gastroparetic and normal rats. (ii) The increased levels of CSE expression in response to gastric distention in diabetic rats were lower than in normal rats. (iii) PAG inhibited the excitatory effect of capsaicin on GER and on tension of spontaneous contractions of strips. (iv) Hydrogen sulphide increased the frequency and tension of spontaneous contractions of gastric strip muscles in normal and diabetic rats. CONCLUSIONS & INFERENCES: The results showed that delayed GER in diabetic rats can be due to down-regulation of H2 S biosynthesis enzyme, CSE and suggested that a potential prokinetic role for H2 S to treat the delayed gastric emptying in diabetic patients.