Reduced stem cell factor links smooth myopathy and loss of interstitial cells of cajal in murine diabetic gastroparesis

A bibliometric analysis of diabetic gastroparesis from 1979 to 2024

Objective

Gastroparesis is one of the complications of diabetes mellitus, which has a major impact on the quality of life of patients, and the limited therapeutic options currently available make it a public health problem. No bibliometric studies on diabetic gastroparesis have been published to date. Therefore, the aim of this paper is to summarize and analyze the research hotspots for researchers.

Methods

Research articles related to Diabetic gastroparesis were searched in Web of Science Core Collection (WOSCC), and relevant information was extracted after screening. A comprehensive bibliometric analysis of 699 publications was conducted using Microsoft Excel 2019, Citespace and VOSviewers.

Result

A total of 699 papers from 738 institutions in 41 countries were retrieved. Publications in this field have increased rapidly since 1979. USA (n = 370) and Mayo Clinical (n = 69) were the most productive country and institution, respectively. Neurogastroenterology and Motility (n = 67) was the most published journal with Parkman, Henry P. (n = 40) having the highest number of articles; Gastroenterology and Mccallum, Richard W. were the most influential journals and authors.

Conclusions

The research hotspots of Diabetic gastroparesis are mainly focused on treatment modalities and pathological mechanisms. Future research in diabetic gastroparesis will focus on exploring the pathomechanisms, finding long-term effective treatments, and improving patients' quality of life.

Inhibition of EZH2 Reduces Aging-Related Decline in Interstitial Cells of Cajal of the Mouse Stomach

BACKGROUND & AIMS

Restricted gastric motor functions contribute to aging-associated undernutrition, sarcopenia, and frailty. We previously identified a decline in interstitial cells of Cajal (ICC; gastrointestinal pacemaker and neuromodulator cells) and their stem cells (ICC-SC) as a key factor of gastric aging. Altered functionality of the histone methyltransferase enhancer of zeste homolog 2 (EZH2) is central to organismal aging. Here, we investigated the role of EZH2 in the aging-related loss of ICC/ICC-SC.

METHODS

klotho mice, a model of accelerated aging, were treated with the most clinically advanced EZH2 inhibitor, EPZ6438 (tazemetostat; 160 mg/kg intraperitoneally twice a day for 3 weeks). Gastric ICC were analyzed by Western blotting and immunohistochemistry. ICC and ICC-SC were quantified by flow cytometry. Gastric slow wave activity was assessed by intracellular electrophysiology. Ezh2 was deactivated in ICC by treating KitcreERT2/+;Ezh2fl/fl mice with tamoxifen. TRP53, a key mediator of aging-related ICC loss, was induced with nutlin 3a in gastric muscle organotypic cultures and an ICC-SC line.

RESULTS

In klotho mice, EPZ6438 treatment mitigated the decline in the ICC growth factor KIT ligand/stem cell factor and gastric ICC. EPZ6438 also improved gastric slow wave activity and mitigated the reduced food intake and impaired body weight gain characteristic of this strain. Conditional genomic deletion of Ezh2 in Kit-expressing cells also prevented ICC loss. In organotypic cultures and ICC-SC, EZH2 inhibition prevented the aging-like effects of TRP53 stabilization on ICC/ICC-SC.

CONCLUSIONS

Inhibition of EZH2 with EPZ6438 mitigates aging-related ICC/ICC-SC loss and gastric motor dysfunction, improving slow wave activity and food intake in klotho mice.

Integration of network pharmacology and experimental verifications reveals the Bian-Se-Tong mixture can alleviate constipation in STC rats by reducing apoptosis of Cajal cells via activating PI3K-Akt signaling pathway

Bian-Se-Tong mixture (BSTM) is an optimized formulation based on the classical prescription "Zhizhu pill", which is widely used in the clinical treatment of slow-transit constipation (STC). The potential molecular mechanism of BSTM therapy for STC was investigated by network pharmacology prediction combined with animal experiments. The active components of BSTM were screened via the TCMSP platform. The GeneCards, OMIM and DrugBank databases were used to search for STC targets. With the help of the Biogenet tool, a protein interaction network between drugs and disease targets was constructed, and the intersection network of the two was extracted to obtain the key targets of BSTM in the treatment of STC. GO and KEGG enrichment analyses of key targets were carried out with Metascape. Loperamide hydrochloride was used to establish an STC rat model, and the key targets and related pathways were preliminarily verified. The important signaling pathways included the PI3K-Akt, MAPK, IL-17, cAMP, and cell cycle signaling pathways. The experimental results showed that BSTM treatment increased the body weight of STC rats and increased the fecal particle number, fecal water content and intestinal carbon ink promotion rate within 24 h. Further pathological changes in the colon of the rats were also observed. In-depth mechanistic studies have shown that BSTM can significantly reduce the apoptosis of intestinal Cajal cells, downregulate the expression of Bax and c-Caspase 3, upregulate the expression of Bcl-2 and c-kit, and promote the phosphorylation of AKT. The results showed that BSTM can significantly relieve constipation in STC rats via a mechanism related to activating the PI3K-Akt signaling pathway and improving Cajal cell apoptosis.

An Overview of Growth Factors as the Potential Link between Psoriasis and Metabolic Syndrome

Psoriasis is a chronic, complex, and immunologically mediated systemic disease that not only affects the skin, but also the joints and nails. It may coexist with various other disorders, such as depression, psoriatic arthritis, cardiovascular diseases, diabetes mellitus, and metabolic syndrome. In particular, the potential link between psoriasis and metabolic syndrome is an issue worthy of attention. The dysregulation of growth factors could potentially contribute to the disturbances of keratinocyte proliferation, inflammation, and itch severity. However, the pathophysiology of psoriasis and its comorbidities, such as metabolic syndrome, remains incompletely elucidated. Growth factors and their abnormal metabolism may be a potential link connecting these conditions. Overall, the objective of this review is to analyze the role of growth factor disturbances in both psoriasis and metabolic syndrome.

Low-intensity pulsed ultrasound at ST36 improves the gastric motility by TNF-α/IKKβ/NF-κB signaling pathway in diabetic rats

BACKGROUND AND AIM

Low-intensity pulsed ultrasound (LIPUS) can effectively regulate the central and peripheral nervous system. However, whether LIPUS could act on acupuncture points to modulate the activity of peripheral nervous has rarely been studied. Our study aimed to investigate whether LIPUS at ST36 could improve gastric emptying in diabetic gastroparesis rats.

METHODS

Sprague-Dawley male rats were divided into three groups: control group (CON), diabetic gastroparesis group (DM), and diabetic gastroparesis LIPUS treated group (LIPUS). The body weight and blood glucose were recorded every week. Glucose tolerance, gastric emptying rate, and gastric motility were measured before and after treatment. Gastric motility was assessed by ultrasonic examination and Muscle strip experiment. The expression level of c-Kit was assessed by immunohistochemistry staining. Levels of TNF-α, p-NF-κB p-65, NF-κB p-65, and p-IKKβ, IKKβ were measured by western blot.

RESULTS

We reported LIPUS at an intensity of 0.88 W/cm2 exhibited significant differences in functional recovery of gastric delayed emptying in diabetic rats. Through ultrasound gastric motility functional testing and analysis of gastric antral smooth muscle strips indirectly and directly proved the effectiveness of LIPUS for the recovery of gastric delayed emptying. Pathological analysis and western blot indicated that the mechanism by which LIPUS applied to ST36 improved gastric motility may be partially attributed to the inhibition of the TNF-α/IKKβ/NF-κB signaling pathway, thereby rescuing the damaged interstitial cells of Cajal network.

CONCLUSION

LIPUS at ST36 improved the gastric motility and rescued the damaged networks of interstitial cells of Cajal. LIPUS may have a promising therapeutic potential for diabetic gastroparesis.

The Crucial Role of the Interstitial Cells of Cajal in Neurointestinal Diseases

Neurointestinal diseases result from dysregulated interactions between the nervous system and the gastrointestinal (GI) tract, leading to conditions such as Hirschsprung's disease and irritable bowel syndrome. These disorders affect many people, significantly diminishing their quality of life and overall health. Central to GI motility are the interstitial cells of Cajal (ICC), which play a key role in muscle contractions and neuromuscular transmission. This review highlights the role of ICC in neurointestinal diseases, revealing their association with various GI ailments. Understanding the functions of the ICC could lead to innovative perspectives on the modulation of GI motility and introduce new therapeutic paradigms. These insights have the potential to enhance efforts to combat neurointestinal diseases and may lead to interventions that could alleviate or even reverse these conditions.

Constipation in DM are associated with both poor glycemic control and diabetic complications: Current status and future directions

Constipation is a major complications of diabetes mellitus. With the accelerating prevalence of diabetes worldwide and an aging population, there is considerable research interest regarding the altered function and structure of the gastrointestinal tract in diabetic patients. Despite current advances in hyperglycemic treatment strategies, the specific pathogenesis of diabetic constipation remains unknown. Patients with constipation, may be reluctant to eat regularly, which may worsen glycemic control and thus worsen symptoms associated with underlying diabetic bowel disease. This paper presents a review of the complex relationship between diabetes and constipation, exploring the morphological alterations and biomechanical remodeling associated with intestinal motility dysfunction, as well as alterations in intestinal neurons, cellular signaling pathways, and oxidative stress. Further studies focusing on new targets that may play a role in the pathogenesis of diabetic constipation may, provide new ideas for the development of novel therapies to treat or even prevent diabetic constipation.

Multiple intratumoral sources of kit ligand promote gastrointestinal stromal tumor

Gastrointestinal stromal tumor (GIST) is the most common human sarcoma and is typically driven by a single mutation in the Kit or PDGFRA receptor. While highly effective, tyrosine kinase inhibitors (TKIs) are not curative. The natural ligand for the Kit receptor is Kit ligand (KitL), which exists in both soluble and membrane-bound forms. While KitL is known to stimulate human GIST cell lines in vitro, we used a genetically engineered mouse model of GIST containing a common human KIT mutation to investigate the intratumoral sources of KitL, importance of KitL during GIST oncogenesis, and contribution of soluble KitL to tumor growth in vivo. We discovered that in addition to tumor cells, endothelia and smooth muscle cells produced KitL in KitV558Δ/+ tumors, even after imatinib therapy. Genetic reduction of total KitL in tumor cells of KitV558Δ/+ mice impaired tumor growth in vivo. Similarly, genetic reduction of tumor cell soluble KitL in KitV558Δ/+ mice decreased tumor size. By RNA sequencing, quantitative PCR, and immunohistochemistry, KitL expression was heterogeneous in human GIST specimens. In particular, PDGFRA-mutant tumors had much higher KitL expression than Kit-mutant tumors, suggesting the benefit of Kit activation in the absence of mutant KIT. Serum KitL was higher in GIST patients with tumors resistant to imatinib and in those with tumors expressing more KitL RNA. Overall, KitL supports the growth of GIST at baseline and after imatinib therapy and remains a potential biomarker and therapeutic target.

Insulin-Like Growth Factor1 Preserves Gastric Pacemaker Cells and Motor Function in Aging via ERK1/2 Activation

BACKGROUND & AIMS

Impaired gastric motor function in the elderly causes reduced food intake leading to frailty and sarcopenia. We previously found that aging-related impaired gastric compliance was mainly owing to depletion of interstitial cells of Cajal (ICC), pacemaker cells, and neuromodulator cells. These changes were associated with reduced food intake. Transformation-related protein 53-induced suppression of extracellular signal-regulated protein kinase (ERK)1/2 in ICC stem cell (ICC-SC) cell-cycle arrest is a key process for ICC depletion and gastric dysfunction during aging. Here, we investigated whether insulin-like growth factor 1 (IGF1), which can activate ERK in gastric smooth muscles and invariably is reduced with age, could mitigate ICC-SC/ICC loss and gastric dysfunction in klotho mice, a model of accelerated aging.

METHODS

Klotho mice were treated with the stable IGF1 analog LONG R3 recombinant human (rh) IGF1 (150 μg/kg intraperitoneally twice daily for 3 weeks). Gastric ICC/ICC-SC and signaling pathways were studied by flow cytometry, Western blot, and immunohistochemistry. Gastric compliance was assessed in ex vivo systems. Transformation-related protein 53 was induced with nutlin 3a and ERK1/2 signaling was activated by rhIGF-1 in the ICC-SC line.

RESULTS

LONG R3 rhIGF1 treatment prevented reduced ERK1/2 phosphorylation and gastric ICC/ICC-SC decrease. LONG R3 rhIGF1 also mitigated the reduced food intake and impaired body weight gain. Improved gastric function by LONG R3 rhIGF1 was verified by in vivo systems. In ICC-SC cultures, rhIGF1 mitigated nutlin 3a-induced reduced ERK1/2 phosphorylation and cell growth arrest.

CONCLUSIONS

IGF1 can mitigate age-related ICC/ICC-SC loss by activating ERK1/2 signaling, leading to improved gastric compliance and increased food intake in klotho mice.

TRPV1 Dysfunction Impairs Gastric Nitrergic Neuromuscular Relaxation in High-Fat Diet-Induced Diabetic Gastroparesis Mice

Diabetic gastroparesis (DGP) is characterized by delayed gastric emptying of solid food. Nitrergic neuron-mediated fundus relaxation and intragastric peristalsis are pivotal for gastric emptying and are impaired in DGP. Transient receptor potential vanilloid 1 (TRPV1) ion channels are expressed in gastrointestinal vagal afferent nerves and have a potential role in relevant gastrointestinal disorders. In this study, mice with high-fat diet (HFD)-induced type 2 diabetes mellitus (T2DM), associated with gastroparesis, were used to determine the role of TRPV1 in DGP. After feeding with HFD, mice exhibited obesity, hyperglycemia, insulin resistance, and delayed gastric emptying. Cholinergic- and nitrergic neuron-mediated neuromuscular contractions and relaxation were impaired. The antral tone of the DGP mice was attenuated. Interestingly, activating or suppressing TRPV1 facilitated or inhibited gastric fundus relaxation in normal mice. These effects were neutralized by using a nitric oxide synthase (NOS) inhibitor. Activation or suppression of TRPV1 also increased or reduced NO release. TRPV1 was specifically localized with neuronal NOS in the gastric fundus. These data suggest that TRPV1 activation facilitates gastric fundus relaxation by regulating neuronal NOS and promoting NO release. However, these effects and mechanisms disappeared in mice with DGP induced by HFD diet. TRPV1 expression was only marginally decreased in the fundus of DGP mice. TRPV1 dysfunction may be a potential mechanism underlying the dysfunction of DGP gastric nitrergic neuromuscular relaxation.

Corticotropin-releasing factor receptor agonists decrease interstitial cells of Cajal in murine colon

BACKGROUND

Peripheral corticotropin-releasing factor (CRF) has been reported to affect gastrointestinal motility through corticotropin-releasing factor receptor located in enteric nervous system (ENS), but less is known about of the relationship between peripheral CRF and interstitial cells of Cajal (ICC).

METHODS

Mice were intraperitoneally injected with CRF receptor agonists to determine their effects on colonic ICC. Chronic heterotypic stress (CHeS) was applied to mice to determine endogenous CRF-CRF receptor signaling on colonic ICC.

RESULTS

We found that stressin1, a selective CRF receptor 1 (CRF₁ ) agonist, significantly increased the expression of CRF₁ but had no effect on the expression of CRF₂ in the smooth muscles of murine colon. The protein expression of c-Kit, Anoctamin-1 (ANO1), and stem cell factor (SCF) in the colonic smooth muscles was significantly decreased in stressin1-treated mice. Accordingly, 2-(4-Chloro-2-methylphenoxy)-N'-(2-methoxybenzylidene) acetohydrazide (Ani 9), a selective ANO1 blocker, had a less significant inhibitory effect on CMMC in stressin1-treated mice compared to the saline-treated ones. Similarly, we also found that ICC and ANO1 were reduced in the colonic smooth muscles of mice by treatment with sauvagine (ip), a CRF₂ agonist. However, different with stressin1, sauvagine decreased the expression of CRF₂ besides increasing CRF₁ expression in the colonic smooth muscles. Similar results of CRF₁ and c-Kit expressions were also obtained from the colon of CHeS-treated mice.

CONCLUSION

All these results suggest that CRF may be involved in the abnormality of colonic motility through peripheral CRF₁ to decrease the number and function of ICC, which provides a potential target for treating stress-induced gastrointestinal motility disorder.

The prevalence of constipation in end-stage kidney disease patients: A cross-sectional observation study

The aim of our study was to determine the prevalence, distribution, and risk factors for constipation in peritoneal dialysis (PD) and hemodialysis (HD) patients in our center. In this cross-sectional study, 858 dialysis patients over 18 years of age (681 HD cases and 177 PD cases from our hospital) were enrolled. A constipation assessment scale (CAS) questionnaire was used to evaluate constipation status. Logistic regression analysis was performed to define independent risk factors for CAS scores. The prevalence of constipation in HD and PD patients was 52.7% and 77.4%, respectively. The mean CAS score in HD and PD patients was 1.73 ± 2.31 and 2.42 ± 2.34, respectively. Age ≥ 65 and diabetic kidney disease for renal failure were independent risk factors associated with constipation in the HD population (OR = 1.67, 95% CI: 1.15-2.90, P = .019; OR = 3.31, 95% CI: 1.65-6.11, P < .001, respectively). In the PD population, only serum prealbumin was independently associated with constipation (OR = 0.88, 95% CI: 0.79-0.96, P = .007). The multivariable logistic regression analysis demonstrated that PD modality, age ≥ 65 and diabetic kidney disease for renal failure were independent risk factors for constipation (OR = 2.15, 95% CI: 1.41-3.32, P < .001; OR = 1.65, 95% CI: 1.13-2.33, P = .003; OR = 3.19, 95% CI: 1.76-5.093, P < .001, respectively). The prevalence of constipation in PD patients was higher than that in HD patients in our center. PD modality for renal replacement therapy, age ≥ 65 and diabetic kidney disease for renal failure were closely associated with constipation in dialysis patients.

Based on Network Pharmacology and Gut Microbiota Analysis to Investigate the Mechanism of the Laxative Effect of Pterostilbene on Loperamide-Induced Slow Transit Constipation in Mice

Background: Pterostilbene (PTE) is a natural polyphenol compound that has been proven to improve intestinal inflammation, but its laxative effect on slow transit constipation (STC) has never been studied. This study aims to investigate the laxative effect of PTE on loperamide (LOP)-induced STC mice and its influence on intestinal microbes through a combination of network pharmacological analysis and experimental verification.

Material and Methods: PTE was used to treat LOP-exposed mice, and the laxative effect of PTE was evaluated by the total intestinal transit time and stool parameters. The apoptosis of Cajal interstitial cells (ICCs) was detected by immunofluorescence. The mechanism of PTE’s laxative effect was predicted by network pharmacology analysis. We used western blot technology to verify the predicted hub genes and pathways. Malondialdehyde (MDA) and GSH-Px were tested to reflect oxidative stress levels and the changes of gut microbiota were detected by 16S rDNA high-throughput sequencing.

Results: PTE treatment could significantly improve the intestinal motility disorder caused by LOP. Apoptosis of ICCs increased in the STC group, but decreased significantly in the PTE intervention group. Through network pharmacological analysis, PTE might reduce the apoptosis of ICCs by enhancing PI3K/AKT and Nrf2/HO-1 signaling, and improve constipation caused by LOP. In colon tissues, PTE improved the Nrf2/HO-1 pathway and upregulated the phosphorylation of AKT. The level of MDA increased and GSH-Px decreased in the STC group, while the level of oxidative stress was significantly reduced in the PTE treatment groups. PTE also promoted the secretion of intestinal hormone and restored the microbial diversity caused by LOP.

Conclusion: Pterostilbene ameliorated the intestinal motility disorder induced by LOP, this effect might be achieved by inhibiting oxidative stress-induced apoptosis of ICCs through the PI3K/AKT/Nrf2 signaling pathway.

Diabetic Gastroenteropathy: Soothe the Symptoms or Unravel a Cure?

Autonomic neuropathy in patients with diabetes mellitus, and especially complications related to gastrointestinal neuropathy, are often overlooked in the clinic. Diabetic gastroenteropathy affects every segment of the gastrointestinal tract and generates symptoms that may include nausea, early satiety, vomiting, abdominal pain, constipation, and diarrhea. Severe cases can be complicated by weight loss, dehydration, and electrolyte disturbances. The pathophysiology is complex, the diagnostics and treatment options are multidisciplinary, and there is generally a lack of evidence for the treatment options. The aims for this review are first to summarize the pathophysiology and describe possible and expected symptoms and complications.Further, we will try to supply the clinician with a straightforward tool for diagnostics, and then, we shall summarize established treatment options, including diet recommendations, pharmacological and non-pharmacological options. Finally, we will explore the multiple possibilities of novel treatment, looking at medications related to the pathophysiology of neuropathy, other manifestations of autonomic neuropathies, and symptomatic treatment for other gastrointestinal disorders, also including new knowledge of endosurgical and neuromodulatory treatment. The overall goal is to increase awareness and knowledge on this frequent diabetic complication and to provide better tools for diagnosis and treatment. Ultimately, we hope to encourage further research in this field, as there are clear shortcomings in terms of biomarkers, pathophysiology, as well as treatment possibilities. In conclusion, diagnosis and management of diabetic gastroenteropathy are challenging and often require multidisciplinary teams and multimodal therapies. Treatment options are sparse, but new pharmacological, endoscopic, and neuromodulatory techniques have shown promising results in initial studies.

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.

Effect of DA-9701 on the Gastrointestinal Motility in the Streptozotocin-Induced Diabetic Mice

Background: Compared to the general population, diabetic patients experience more frequent episodes of gastrointestinal (GI) motility dysfunction, owing to the disruption of functional innervations. DA-9701 is a new prokinetic agent formulated from the extracts of Pharbitidis semen and Corydalis tuber. Aim: To investigate the effect of DA-9701 on GI motility in an animal model of streptozotocin (STZ)-induced diabetes. Methods: Diabetes was induced in mice by intraperitoneal injection of STZ (40 mg/kg of body weight in 0.1 M citrate buffer) for 3 days. Diabetic mice were divided into four groups and administered DA-9701 in different doses (1, 3, and 10 mg/kg) or placebo for 2 weeks. Intestinal transit was assessed using charcoal meal movement. GI isometric contraction was measured by applying an isometric force transducer on a circular muscle strip of the antrum, ileum, and proximal colon of sacrificed mice. Gastric emptying rate was evaluated by measuring the dye percentage remaining in the stomach relative to the total dye amount recovered in a standardization group of mice. Results: Body weight and antral and small intestinal motility were less in diabetic mice than in control mice, and colonic motility was similar in both. DA-9701 showed a dose-dependent increase in the amplitude of spontaneous phasic contractions in the antrum, ileum, and colon in diabetic mice without influencing body weight or blood glucose levels. The degree of improvement was comparable between diabetic and control mice. Intestinal transit was significantly more delayed in diabetic mice than in controls (43 ± 7% vs. 67 ± 8%, p < 0.05); however, DA-9701 restored the delayed intestinal transit more effectively compared to placebo (75% vs. 50%). The gastric emptying rate was significantly more delayed in diabetic mice than in controls (43 ± 10% vs. 62 ± 12%, p < 0.05), and was improved by DA-9701 in a dose-dependent manner (50%, 55%, and 60% in mice treated with 1, 3, and 10 mg/kg of DA-9701, respectively, vs. 43% in placebo-treated and 60% in control mice). Conclusions: DA-9701 improved GI contractility without affecting blood sugar and body weight in diabetic mice. DA-9701 could improve the decreased GI motility and clinical symptoms in progressive diabetic patients.

Interstitial cells of Cajal and human colon motility in health and disease

Our understanding of human colonic motility, and autonomic reflexes that generate motor patterns, has increased markedly through high-resolution manometry. Details of the motor patterns are emerging related to frequency and propagation characteristics that allow linkage to interstitial cells of Cajal (ICC) networks. In studies on colonic motor dysfunction requiring surgery, ICC are almost always abnormal or significantly reduced. However, there are still gaps in our knowledge about the role of ICC in the control of colonic motility and there is little understanding of a mechanistic link between ICC abnormalities and colonic motor dysfunction. This review will outline the various ICC networks in the human colon and their proven and likely associations with the enteric and extrinsic autonomic nervous systems. Based on our extensive knowledge of the role of ICC in the control of gastrointestinal motility of animal models and the human stomach and small intestine, we propose how ICC networks are underlying the motor patterns of the human colon. The role of ICC will be reviewed in the autonomic neural reflexes that evoke essential motor patterns for transit and defecation. Mechanisms underlying ICC injury, maintenance, and repair will be discussed. Hypotheses are formulated as to how ICC dysfunction can lead to motor abnormalities in slow transit constipation, chronic idiopathic pseudo-obstruction, Hirschsprung's disease, fecal incontinence, diverticular disease, and inflammatory conditions. Recent studies on ICC repair after injury hold promise for future therapies.

Auricular vagal nerve stimulation enhances gastrointestinal motility and improves interstitial cells of Cajal in rats treated with loperamide

BACKGROUND

Gastrointestinal (GI) motility disorders affect a large proportion of the population with limited treatment options. The aims of this study were to investigate the potential of a non-invasive method of auricular vagal nerve stimulation (aVNS) for treating GI dysmotility and to explore possible mechanisms involving slow waves and interstitial cells of Cajal (ICC).

METHODS

Normal rats were treated daily with loperamide for 1 week and then treated, while still on daily loperamide, with aVNS/Sham-aVNS for another 1 week. Gastric emptying (GE), small intestine transit (SIT), and GI slow waves were measured. The plasma level of pancreatic polypeptide (PP) and noradrenaline (NE) was assessed by ELISA. ICC in the gastric antrum were detected by immunohistochemistry.

KEY RESULTS

(a) aVNS significantly increased the percentage of normal GI slow waves (p < 0.05 for both fasting and postprandial states, vs. Sham-aVNS) and accelerated GE (p < 0.05, vs. Sham-aVNS) and SIT (p < 0.05, vs. Sham-aVNS) impaired by loperamide. (b) aVNS increased plasma PP (p < 0.01) and decreased plasma NE (p < 0.01), compared with Sham-aVNS. (c) Gastric ICC was decreased by loperamide (p < 0.01) but increased after aVNS (p < 0.01, vs. Sham aVNS).

CONCLUSIONS & INFERENCES

Loperamide induces upper GI dysmotility. aVNS accelerates upper GI transit and improving pace-making activity mediated via the ICC. Non-invasive aVNS may have a therapeutic potential for upper GI dysmotility.

Assessment of pyloric sphincter distensibility and pressure in patients with diabetic gastroparesis

BACKGROUND

Recent studies have shown that pyloric distensibility is altered in 30-50% of gastroparetic patients but the number of diabetic patients included in prior reports has been small. The aim of the present study was to assess pyloric sphincter measurements in diabetic patients with gastroparesis and to determine whether diabetes characteristics were correlated to pyloric disfunction.

METHODS

Pyloric distensibility and pressure were measured using EndoFLIP^® system in 46 patients with diabetic gastroparesis (DGP) and compared with 21 healthy volunteers (HV), and 33 patients with idiopathic gastroparesis (IGP). Altered pyloric distensibility was defined as the measurement below 10 mm² /mmHg at 40 ml of inflation. In diabetic patients, blood glucose, glycated hemoglobin, duration, complications, and treatments were collected.

KEY RESULTS

Mean pyloric distensibility at 40 ml of inflation was lower in DGP and IGP groups with, respectively, 10.8 ± 0.9 mm² /mmHg and 14.8 ± 2.2 mm² /mmHg in comparison with the HV group (25.2 ± 2.3 mm² /mmHg; p < 0.005). 56.5% of patients had a decreased pyloric distensibility in the DGP group, 51.5% of patients in the IGP group, and 10% of patients in the HV group. No correlation was found between pyloric sphincter measurements and diabetes characteristics, including blood glucose, glycated hemoglobin, diabetes mellitus type, neuropathy, or GLP1 agonists intake.

CONCLUSION AND INTERFERENCES

Pyloric sphincter distensibility and pressure were altered both in diabetic and idiopathic gastroparesis. Pyloric sphincter distensibility was not correlated to diabetes parameters.

Gastric Emptying Time and Volume of the Small Intestine as Objective Markers in Patients With Symptoms of Diabetic Enteropathy

Background/Aims

Patients with diabetes mellitus (DM) often suffer from gastrointestinal (GI) symptoms, but these correlate poorly to established objective GI motility measures. Our aim is to perform a detailed evaluation of potential measures of gastric and small intestinal motility in patients with DM type 1 and severe GI symptoms.

Methods

Twenty patients with DM and 20 healthy controls (HCs) were included. GI motility was examined with a 3-dimensional-Transit capsule, while organ volumes were determined by CT scans.

Results

Patients with DM and HCs did not differ with regard to median gastric contraction frequency (DM 3.0 contractions/minute [interquartile range {IQR}, 2.9-3.0]; HCs 2.9 [IQR, 2.8-3.1]; P = 0.725), amplitude of gastric contractions (DM 9 mm [IQR, 8-11]; HCs 11 mm (IQR, 9-12); P = 0.151) or fasting volume of the stomach wall (DM 149 cm3 [IQR, 112-187]; HCs 132 cm3 [IQR, 107-154]; P = 0.121). Median gastric emptying time was prolonged in patients (DM 3.3 hours [IQR, 2.6-4.6]; HCs 2.4 hours [IQR, 1.8-2.7]; P = 0.002). No difference was found in small intestinal transit time (DM 5 hours [IQR, 3.7-5.6]; HCs 4.8 hours [IQR, 3.9-6.0]; P = 0.883). However, patients with DM had significantly larger volume of the small intestinal wall (DM 623 cm3 [IQR, 487-766]; HCs 478 cm3 [IQR, 393-589]; P = 0.003). Among patients, 13 (68%) had small intestinal wall volume and 9 (50%) had gastric emptying time above the upper 95% percentile of HCs.

Conclusion

In our study, gastric emptying time and volume of the small intestinal wall appeared to be the best objective measures in patients with DM type 1 and symptoms and gastroenteropathy.

Electroacupuncture Regularizes Gastric Contraction and Reduces Apoptosis of Interstitial Cells of Cajal in Diabetic Rats

Background/Aims

Gastric dysmotility is a frequent complication among patients with diabetes mellitus. Electroacupuncture (EA) has been empirically used to relieve gastrointestinal symptoms. The aims of this study were to investigate the effects of EA on gastric contraction and the mechanisms of interstitial cells of Cajal (ICC) involved.

Materials and Methods

Male Sprague–Dawley rats were randomized into the normal control, diabetes (DM), diabetic and sham EA (DM + SEA), diabetic and low-frequency EA (DM + LEA), and diabetic and high-frequency EA (DM + HEA) groups. Diabetic models were established and then treated with EA for 8 weeks. Body weight and blood glucose were recorded every 2 weeks. The spontaneous contractions of distal gastric strips were analyzed. Immunostaining and RT-PCR were used to test the apoptotic ICC, IGF-1/IGF-1R, and Nrf2/HO-1 pathways.

Results

The body weight in the DM + LEA and DM + HEA groups were increased compared with that of the DM group, though there was no effect on the blood glucose. The gastric contractions were obviously disordered in the DM group, but EA could regularize the contractions. The number of apoptotic ICC was dramatically increased in the DM group, but reduced with EA treatment. Meanwhile, the IGF-1/IGF-1R pathway was verified to be significantly altered in diabetic rats. The Nrf2/HO-1 pathway was not significantly increased in the DM group. EA with different frequencies efficiently improved the expression of IGF-1/IGF-1R signaling and activated the Nrf2/HO-1 pathway.

Conclusion

EA could improve gastric motility dysfunction and attenuate ICC apoptosis possibly through the regulation of IGF-1/IGF-1R and Nrf2/HO-1 pathways. EA may be a potential therapeutic method for diabetic gastric motility dysfunction.

Gastric Electrical Pacing Reduces Apoptosis of Interstitial Cells of Cajal via Antioxidative Stress Effect Attributing to Phenotypic Polarization of M2 Macrophages in Diabetic Rats

BACKGROUND

Gastric electrical pacing (GEP) could restore interstitial cells of Cajal in diabetic rats. M2 macrophages contribute to the repair of interstitial cells of Cajal injury though secreting heme oxygenase-1 (HO-1). The aim of the study is to investigate the effects and mechanisms of gastric electrical pacing on M2 macrophages in diabetic models.

METHODS

Sixty male Sprague-Dawley rats were randomized into control, diabetic (DM), diabetic with the sham GEP (DM+SGEP), diabetic with GEP1 (5.5 cpm, 100 ms, 4 mA) (DM+GEP1), diabetic with GEP2 (5.5 cpm, 300 ms, 4 mA) (DM+GEP2), and diabetic with GEP3 (5.5 cpm, 550 ms, 4 mA) (DM+GEP3) groups. The apoptosis of interstitial cells of Cajal and the expression of macrophages were detected by immunofluorescence technique. The expression levels of the Nrf2/HO-1 and NF-κB pathway were evaluated using western blot analysis or immunohistochemical method. Malonaldehyde, superoxide dismutase, and reactive oxygen species were tested to reflect the level of oxidative stress.

RESULTS

Apoptosis of interstitial cells of Cajal was increased in the DM group but significantly decreased in the DM+GEP groups. The total number of macrophages was almost the same in each group. In the DM group, M1 macrophages were increased and M2 macrophages were decreased. However, M2 macrophages were dramatically increased and M1 macrophages were reduced in the DM+GEP groups. Gastric electrical pacing improved the Nrf2/HO-1 pathway and downregulated the phosphorylation of NF-κB. In the DM group, the levels of malonaldehyde and reactive oxygen species were elevated and superoxide dismutase was lowered, while gastric electrical pacing reduced the levels of malonaldehyde and reactive oxygen species and improved superoxide dismutase.

CONCLUSION

Gastric electrical pacing reduces apoptosis of interstitial cells of Cajal though promoting M2 macrophages polarization to play an antioxidative stress effect in diabetic rats, which associates with the activated Nrf2/HO-1 pathway and the phosphorylation of NF-κB pathway.

Diabetic gastroparesis: An overview of pathogenesis, clinical presentation and novel therapies, with a focus on ghrelin receptor agonists

Diabetic gastroparesis is defined as delayed gastric emptying without mechanical obstruction in the setting of diabetes. Symptoms range from mild bloating to severe vomiting episodes and can result in frequent hospitalizations and poor quality of life. It is suspected that diabetic gastroparesis is underdiagnosed due to its similar presentation to other conditions such as gastroesophageal reflux disease. The pathogenesis of diabetic gastroparesis remains unclear, but proposed mechanisms include vagal dysfunction, hyperglycemia, interstitial cells of Cajal network disturbances, loss of neural nitric oxide synthase expression in the myenteric plexus, and oxidative stress. Current management for diabetic gastroparesis focuses on dietary and lifestyle changes as well as improved glycemic control. Limited options for medical therapies are available that include prokinetic and antiemetic medications. Metoclopramide is the only FDA-approved medication for the treatment of gastroparesis. Metoclopramide improves symptoms of gastroparesis although extended treatment presents challenges such as decreased efficacy over time and increased risks for adverse events. We summarize the current knowledge of the pathophysiology of diabetic gastroparesis and review current and investigational treatments for diabetes gastroparesis.

Colonic motility in patients with type 1 diabetes and gastrointestinal symptoms

BACKGROUND

Gastrointestinal (GI) symptoms are common in patients with diabetes mellitus (DM). The electromagnetic 3D-Transit system allows assessment of regional transit times and motility patterns throughout the GI tract. We aimed to compare GI transit times and detailed motility patterns of the colon in patients with DM and GI symptoms to those of healthy controls (HC). We further aimed to determine whether any abnormalities in motility were reversible by cholinergic stimulation.

METHODS

We compared 18 patients with DM with 20 HC by means of the 3D-Transit system. Patients were studied before and during oral administration of 60 mg pyridostigmine.

KEY RESULTS

Compared to HC, patients had prolonged gastric emptying (DM: 3.3 hours (interquartile range (IQR) 2.6-4.6); HC: 2.3 hours (IQR 1.7-2.7) (P < .01)), colonic transit time (DM: 52.6 hours (IQR 23.3-83.0); HC: 22.4 hours (IQR 18.9-43.6) (P = .02)), and whole gut transit time (DM: 69.4 hours (IQR 32.9-103.6); HC: 30.3 hours (IQR 25.2-49.9) (P < .01)). In addition, compared to HC, patients had prolonged transit time in the ascending colon (DM: 20.5 hours (IQR 11.0-44.0); HC: 8.0 hours (IQR 3.8-21.0) (P < .05)) and more slow retrograde movements in the colon (DM: 2 movements (IQR 1-4); HC: 1 movement (IQR 0-1) (P = .01)). In patients, pyridostigmine increased the number of bowel movements (P < .01) and reduced small intestine transit times (P < .05).

CONCLUSIONS

Patients with DM and GI symptoms have longer than normal GI transit times. This is only partly reversible by pyridostigmine. The increased number of retrograde colonic movements in patients could potentially explain the abnormally long transit time in proximal colon.

Wnt-induced, TRP53-mediated Cell Cycle Arrest of Precursors Underlies Interstitial Cell of Cajal Depletion During Aging

BACKGROUND & AIMS

Gastric dysfunction in the elderly may cause reduced food intake, frailty, and increased mortality. The pacemaker and neuromodulator cells interstitial cells of Cajal (ICC) decline with age in humans, and their loss contributes to gastric dysfunction in progeric klotho mice hypomorphic for the anti-aging Klotho protein. The mechanisms of ICC depletion remain unclear. Klotho attenuates Wnt (wingless-type MMTV integration site) signaling. Here, we examined whether unopposed Wnt signaling could underlie aging-associated ICC loss by up-regulating transformation related protein TRP53 in ICC stem cells (ICC-SC).

METHODS

Mice aged 1-107 weeks, klotho mice, APC^Δ468 mice with overactive Wnt signaling, mouse ICC-SC, and human gastric smooth muscles were studied by RNA sequencing, reverse transcription-polymerase chain reaction, immunoblots, immunofluorescence, histochemistry, flow cytometry, and methyltetrazolium, ethynyl/bromodeoxyuridine incorporation, and ex-vivo gastric compliance assays. Cells were manipulated pharmacologically and by gene overexpression and RNA interference.

RESULTS

The klotho and aged mice showed similar ICC loss and impaired gastric compliance. ICC-SC decline preceded ICC depletion. Canonical Wnt signaling and TRP53 increased in gastric muscles of klotho and aged mice and middle-aged humans. Overstimulated canonical Wnt signaling increased DNA damage response and TRP53 and reduced ICC-SC self-renewal and gastric ICC. TRP53 induction persistently inhibited G₁/S and G₂/M cell cycle phase transitions without activating apoptosis, autophagy, cellular quiescence, or canonical markers/mediators of senescence. G₁/S block reflected increased cyclin-dependent kinase inhibitor 1B and reduced cyclin D1 from reduced extracellular signal-regulated kinase activity.

CONCLUSIONS

Increased Wnt signaling causes age-related ICC loss by up-regulating TRP53, which induces persistent ICC-SC cell cycle arrest without up-regulating canonical senescence markers.

Understanding the Biology of Human Interstitial Cells of Cajal in Gastrointestinal Motility

Millions of patients worldwide suffer from gastrointestinal (GI) motility disorders such as gastroparesis. These disorders typically include debilitating symptoms, such as chronic nausea and vomiting. As no cures are currently available, clinical care is limited to symptom management, while the underlying causes of impaired GI motility remain unaddressed. The efficient movement of contents through the GI tract is facilitated by peristalsis. These rhythmic slow waves of GI muscle contraction are mediated by several cell types, including smooth muscle cells, enteric neurons, telocytes, and specialised gut pacemaker cells called interstitial cells of Cajal (ICC). As ICC dysfunction or loss has been implicated in several GI motility disorders, ICC represent a potentially valuable therapeutic target. Due to their availability, murine ICC have been extensively studied at the molecular level using both normal and diseased GI tissue. In contrast, relatively little is known about the biology of human ICC or their involvement in GI disease pathogenesis. Here, we demonstrate human gastric tissue as a source of primary human cells with ICC phenotype. Further characterisation of these cells will provide new insights into human GI biology, with the potential for developing novel therapies to address the fundamental causes of GI dysmotility.

Laxative Effects of Yangyin Tongmi Capsule on a Model of Diphenoxylate-Induced Constipation in Mice

Constipation is characterized by reduced number of bowel movements, dry stools, and difficult defecation. Yangyin Tongmi capsule (YTC), a traditional Chinese formula, is used in the treatment of constipation, while the underlying mechanisms remain unknown. Herein, this work attempted to prove the effects of YTC on constipation treatment and its possible mechanisms. KM mice were randomly divided into four groups (n = 10/group) and treated with double distilled water (Control), diphenoxylate (Model: 10 mg/kg), or diphenoxylate plus low-dose YTC (L-YTC: 0.6 g/kg) or high-dose YTC (H-YTC: 1.2 g/kg). The data indicated that YTC can significantly shorten the discharge time of the first black stool, improve intestinal propulsion rate, and increase the water content and quantity of feces in mice. ELISA suggested that YTC regulate the content of intestinal hormones and neurotransmitters, such as motilin (MTL), gastrin (GT), somatostatin (SST), substance P (SP), acetylcholine (Ach), and nitric oxide (NO). The expression levels of aquaporin 3 (AQP3) and aquaporin 8 (AQP8) in the colon were examined by immunohistochemistry. In the meantime, the expression levels of P2X2, C-kit, and stem cell factor (SCF) in the colon were examined by western blot analysis. The results of this study suggest that YTC has mitigative effects on diphenoxylate-induced constipation by regulating the content of intestinal hormones and neurotransmitters and regulating the expression of related proteins in the colon.

Association between interstitial cells of Cajal and anti-vinculin antibody in human stomach

Interstitial cells of Cajal (ICC) are known as the pacemaker cells of gastrointestinal tract, and it has been reported that acute gastroenteritis induces intestinal dysmotility through antibody to vinculin, a cytoskeletal protein in gut, resulting in small intestinal bacterial overgrowth, so that anti-vinculin antibody can be used as a biomarker for irritable bowel syndrome. This study aimed to determine correlation between serum anti-vinculin antibody and ICC density in human stomach. Gastric specimens from 45 patients with gastric cancer who received gastric surgery at Kangwon National University Hospital from 2013 to 2017 were used. ICC in inner circular muscle, and myenteric plexus were counted. Corresponding patient's blood samples were used to determine the amount of anti-vinculin antibody by enzyme-linked immunosorbent assay. Analysis was done to determine correlation between anti-vinculin antibody and ICC numbers. Patients with elevated anti-vinculin antibody titer (above median value) had significantly lower number of ICC in inner circular muscle (71.0 vs. 240.5, p = 0.047), and myenteric plexus (12.0 vs. 68.5, p < 0.01) compared to patients with lower anti-vinculin antibody titer. Level of serum anti-vinculin antibody correlated significantly with density of ICC in myenteric plexus (r = −0.379, p = 0.01; Spearman correlation). Increased level of circulating anti-vinculin antibody was significantly correlated with decreased density of ICC in myenteric plexus of human stomach.

Enteric cholinergic neuropathy in patients with diabetes: Non-invasive assessment with positron emission tomography

BACKGROUND

¹¹ C-Donepezil positron emission tomography (PET) allows non-invasive assessment of cholinergic innervation of visceral organs. We aimed to compare cholinergic innervation in the gut in patients with diabetes mellitus (DM) and in healthy controls (HC).

METHODS

¹¹ C-Donepezil PET and computed tomography (CT) were performed in 19 patients with type 1 DM and gastrointestinal symptoms and in 19 age- and sex-matched HC in a cross-sectional design.

KEY RESULTS

All patients had severe gastrointestinal symptoms when assessed by standard questionnaires. DM patients had significantly increased volume of the small intestinal wall (DM: median 557 cm³ [interquartile range [IQR] 446-697] vs HC median: 448 cm³ [IQR; 341-518; P < .01]), and the ¹¹ C Donepezil PET uptake was reduced in patients (DM: median 7.08 standardized uptake value [SUV] [IQR; 5.94-8.43] vs HC: median 9.18 SUV [IQR; 8.57-10.11; P < .01]). A similar pattern was found in colon (DM: median volume 1064 cm³ [IQR; 882-1312] vs HC: median 939 cm³ [IQR; 785-1081; P = .13] and DM: median 1.22 SUV (IQR; 1.08-1.36) vs HC: median 1.42 SUV (IQR; 1.32-1.53; P = .03). Furthermore, patients had significantly reduced pancreatic volume (DM: median 53 cm³ [IQR; 41-69] vs HC: median 98 cm³ [IQR;82-110; P < .01]) and reduced PET uptake of the pancreas (DM: median 13.14 SUV [IQR;9.58-15.82] vs HC: median 21.46 SUV [IQR;18.97-24.06; P < .01]) as well as the adrenal gland (DM: median 7.62 SUV [IQR;7.61;15.82] vs HC: median 15.51 SUV [IQR;12.22;19.49; P = .03]).

CONCLUSION AND INFERENCES

Assessed with ¹¹ C-Donepezil PET/CT, patients with DM and severe bowel symptoms have reduced cholinergic innervation of the gut indicative of parasympathetic denervation.

Gastroparesis: a turning point in understanding and treatment

Gastroparesis is defined by delayed gastric emptying (GE) and symptoms of nausea, vomiting, bloating, postprandial fullness, early satiety and abdominal pain. Most common aetiologies include diabetes, postsurgical and postinfectious, but in many cases it is idiopathic. Clinical presentation and natural history vary by the aetiology. There is significant morbidity and healthcare utilisation associated with gastroparesis. Mechanistic studies from diabetic animal models of delayed GE as well as human full-thickness biopsies have significantly advanced our understanding of this disorder. An innate immune dysregulation and injury to the interstitial cells of Cajal and other components of the enteric nervous system through paracrine and oxidative stress mediators is likely central to the pathogenesis of gastroparesis. Scintigraphy and 13C breath testing provide the most validated assessment of GE. The stagnant gastroparesis therapeutic landscape is likely to soon see significant changes. Relatively newer treatment strategies include antiemetics (aprepitant), prokinetics (prucalopride, relamorelin) and fundic relaxants (acotiamide, buspirone). Endoscopic pyloromyotomy appears promising over the short term, especially for symptoms of nausea and vomiting. Further controlled trials and identification of the appropriate subgroup with pyloric dysfunction and assessment of long-term outcomes are essential. This review highlights the clinical presentation, diagnosis, mechanisms and treatment advancements for gastroparesis.

Hyperglycemia in the early stages of type 1 diabetes accelerates gastric emptying through increased networks of interstitial cells of Cajal

Gastric emptying (GE) can be either delayed or accelerated in diabetes mellitus (DM). However, most research has focused on delayed GE mediated by a chronic hyperglycemic condition in DM. As such, the function of GE in the early stages of DM is not well understood. Interstitial cells of Cajal (ICC) are pacemaker cells in the gastrointestinal tract. In the present study, we investigated changes in GE and ICC networks in the early stages of DM using a streptozotocin-induced type 1 diabetic mouse model. The changes in GE were measured by the 13C-octanoic acid breath test. ICC networks were immunohistochemically detected by an antibody for c-Kit, a specific marker for ICC. Our results showed that GE in type 1 DM was significantly accelerated in the early stages of DM (2-4 weeks after onset). In addition, acute normalization of blood glucose levels by a single administration of insulin did not recover normal GE. ICC networks of the gastric antrum were significantly increased in DM and were not affected by the acute normalization of blood glucose. In conclusion, our results suggest that GE is accelerated in the early stages of DM, and it is associated with increased ICC networks. This mechanism may help to clarify a link between the onset of DM and GE disorders.

Diabetic Gastroparesis

This review covers the epidemiology, pathophysiology, clinical features, diagnosis, and management of diabetic gastroparesis, and more broadly diabetic gastroenteropathy, which encompasses all the gastrointestinal manifestations of diabetes mellitus. Up to 50% of patients with type 1 and type 2 DM and suboptimal glycemic control have delayed gastric emptying (GE), which can be documented with scintigraphy, 13C breath tests, or a wireless motility capsule; the remainder have normal or rapid GE. Many patients with delayed GE are asymptomatic; others have dyspepsia (i.e., mild to moderate indigestion, with or without a mild delay in GE) or gastroparesis, which is a syndrome characterized by moderate to severe upper gastrointestinal symptoms and delayed GE that suggest, but are not accompanied by, gastric outlet obstruction. Gastroparesis can markedly impair quality of life, and up to 50% of patients have significant anxiety and/or depression. Often the distinction between dyspepsia and gastroparesis is based on clinical judgement rather than established criteria. Hyperglycemia, autonomic neuropathy, and enteric neuromuscular inflammation and injury are implicated in the pathogenesis of delayed GE. Alternatively, there are limited data to suggest that delayed GE may affect glycemic control. The management of diabetic gastroparesis is guided by the severity of symptoms, the magnitude of delayed GE, and the nutritional status. Initial options include dietary modifications, supplemental oral nutrition, and antiemetic and prokinetic medications. Patients with more severe symptoms may require a venting gastrostomy or jejunostomy and/or gastric electrical stimulation. Promising newer therapeutic approaches include ghrelin receptor agonists and selective 5-hydroxytryptamine receptor agonists.

Pathophysiology and management of diabetic gastroenteropathy

Polyneuropathy is a common complication to diabetes. Neuropathies within the enteric nervous system are associated with gastroenteropathy and marked symptoms that severely reduce quality of life. Symptoms are pleomorphic but include nausea, vomiting, dysphagia, dyspepsia, pain, bloating, diarrhoea, constipation and faecal incontinence. The aims of this review are fourfold. First, to provide a summary of the pathophysiology underlying diabetic gastroenteropathy. Secondly to give an overview of the diagnostic methods. Thirdly, to provide clinicians with a focussed overview of current and future methods for pharmacological and nonpharmacological treatment modalities. Pharmacological management is categorised according to symptoms arising from the upper or lower gut as well as sensory dysfunctions. Dietary management is central to improvement of symptoms and is discussed in detail, and neuromodulatory treatment modalities and other emerging management strategies for diabetic gastroenteropathy are discussed. Finally, we propose a diagnostic/investigation algorithm that can be used to support multidisciplinary management.

MALAT1 as a Diagnostic and Therapeutic Target in Diabetes-Related Complications: A Promising Long-Noncoding RNA

Diabetes mellitus is a global issue with increasing incidence rate worldwide. In an uncontrolled case, it can advance to various organ-related complications leading to an increase in morbidity and mortality. Long non-coding RNA (lncRNA) Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) appears to be a fairly novel lncRNA that is relevant to diabetes and its role in diabetic-related diseases initiation and progression have long been a subject of attention to many scholars. The expression of MALAT1 is elevated in different diabetic-related diseases. In this review, we demonstrate the various functions of MALAT1 in the different diabetes-related complications including ischemic reperfusion injury, retinopathy, cataract, atherosclerosis, cardiomyopathy, non-alcoholic steatohepatitis, gastroparesis, kidney disease, and gestational diabetes. The emerging evidence showed that the role of MALAT1 in diabetic-related complications is both pro-inflammatory and apoptosis in different cell types. These results concluded that MALAT1 is a potential diagnostic and future targeted therapy for diabetes-associated complications.

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.

Gastrointestinal Dysmotility in MNGIE: from thymidine phosphorylase enzyme deficiency to altered interstitial cells of Cajal

Background

MNGIE is a rare and fatal disease in which absence of the enzyme thymidine phosphorylase induces systemic accumulation of thymidine and deoxyuridine and secondary mitochondrial DNA alterations. Gastrointestinal (GI) symptoms are frequently reported in MNGIE patients, however, they are not resolved with the current treatment interventions.

Recently, our understanding of the GI pathology has increased, which rationalizes the pursuit of more targeted therapeutic strategies. In particular, interstitial cells of Cajal (ICC) play key roles in GI physiology and are involved in the pathogenesis of the GI dysmotility. However, understanding of the triggers of ICC deficits in MNGIE is lacking. Herein, we review the current knowledge about the pathology of GI dysmotility in MNGIE, discuss potential mechanisms in relation to ICC loss/dysfunction, remark on the limited contribution of the current treatments, and propose intervention strategies to overcome ICC deficits. Finally, we address the advances and new research avenues offered by organoids and tissue engineering technologies, and propose schemes to implement to further our understanding of the GI pathology and utility in regenerative and personalized medicine in MNGIE.

Conclusion

Interstitial cells of Cajal play key roles in the physiology of the gastrointestinal motility. Evaluation of their status in the GI dysmotility related to MNGIE would be valuable for diagnosis of MNGIE. Understanding the underlying pathological and molecular mechanisms affecting ICC is an asset for the development of targeted prevention and treatment strategies for the GI dysmotility related to MNGIE.

Diabetic Gastroparesis and Nondiabetic Gastroparesis

Gastroparesis can be divided into diabetic and nondiabetic, and the 3 main causes of gastroparesis are diabetic, postsurgical, and idiopathic. Delayed gastric emptying is the main manifestation of motility disorders for gastroparesis. Symptoms of gastroparesis are nonspecific and severity can vary. Nausea and vomiting are more common in diabetic gastroparesis whereas abdominal pain and early satiety are more frequent in idiopathic gastroparesis. Medication is still the mainstay of treatment of gastroparesis; however, the development of gastric electric stimulation and gastric peroral endoscopic pyloromyotomy brings more options for the treatment of diabetic and nondiabetic gastroparesis.

KIT as a therapeutic target for non-oncological diseases

KIT is a receptor tyrosine kinase that after binding to its ligand stem cell factor activates signaling cascades linked to biological processes such as proliferation, differentiation, migration and cell survival. Based on studies performed on SCF and/or KIT mutant animals that presented anemia, sterility, and/or pigmentation disorders, KIT signaling was mainly considered to be involved in the regulation of hematopoiesis, gametogenesis, and melanogenesis. More recently, novel animal models and ameliorated cellular and molecular techniques have led to the discovery of a widen repertoire of tissue compartments and functions that are being modulated by KIT. This is the case for the lung, heart, nervous system, gastrointestinal tract, pancreas, kidney, liver, and bone. For this reason, the tyrosine kinase inhibitors that were originally developed for the treatment of hemato-oncological diseases are being currently investigated for the treatment of non-oncological disorders such as asthma, rheumatoid arthritis, and alzheimer's disease, among others. The beneficial effects of some of these tyrosine kinase inhibitors have been proven to depend on KIT inhibition. This review will focus on KIT expression and regulation in healthy and pathologic conditions other than cancer. Moreover, advances in the development of anti-KIT therapies, including tyrosine kinase inhibitors, and their application will be discussed.

Long-Pulse Gastric Electrical Stimulation Repairs Interstitial Cells of Cajal and Smooth Muscle Cells in the Gastric Antrum of Diabetic Rats

Background/Aims

The damage of interstitial cells of Cajal and smooth muscle cells has far-reaching implications in the pathogenesis of gastroparesis in diabetic patients. Gastric electrical stimulation (GES) is an efficient therapy for gastric motility disorders, but the mechanisms of GES require clarification.

Methods

Male rats were randomly divided into the control group, diabetic rat group (DM), diabetic rats with sham GES group (DM + SGES), and diabetic rats with different frequency GES group (DM + GES) (GES1: 5.5 cpm, 100 ms, 4 mA; GES2: 5.5 cpm, 300 ms, 4 mA; and GES3: 5.5 cpm, 550 ms, 2 mA). Gastric contractions were explored using the organ bath technique. The alterations of interstitial cells of Cajal, the SCF/c-kit pathway, and smooth muscle cells were also investigated.

Results

(1) Gastric contractions were significantly improved in the DM + GES group compared with those in the DM group. (2) The damage of interstitial cells of Cajal was prevented in the DM + GES group in contrast to the DM group. Moreover, long-pulse GES increased the expression of the SCF/c-kit pathway. More proliferated interstitial cells of Cajal in muscle layers were observed obviously in the DM + GES group. (3) The number of smooth muscle cells in the DM group was not significantly decreased compared with that in the control group. However, ultrastructural changes were distinctly damaged in the DM group. The application of GES protected against the alteration of the ultrastructures of smooth muscle cells.

Conclusions

Long-pulse GES improves gastric contraction possibly by enhancing the proliferation of interstitial cells of Cajal and restoring the injury of smooth muscle cells.

Diabetic gastroparesis: current challenges and future prospects

Diabetic gastroparesis (DMGP) is a condition of delayed gastric emptying after gastric outlet obstruction has been excluded. Symptoms of nausea, vomiting, early satiety, bloating, and abdominal pain are associated with DMGP. Uncontrolled symptoms can lead to overall poor quality of life and financial burdens on the healthcare system. A combination of antiemetics and prokinetics is used in symptom control; metoclopramide is the main prokinetic available for clinical use and is the only U.S. Food and Drug Administration-approved agent in the United States. However, a black box warning in 2009 reporting its association with tardive dyskinesia and recommending caution in chronically using this agent beyond 3 months has decreased its role in clinical practice. There is an unmet need for new prokinetics with good efficacy and safety profiles. Currently, there are several new drugs with different mechanisms of action in the pipeline that are under investigation and show promising preliminary results. Surgically combining gastric electrical stimulation with pyloroplasty is considered "gold" standard. Advances in therapeutic endoscopic intervention with gastric per-oral endoscopic pyloromyotomy have also been shown to improve gastric emptying and gastroparesis (GP) symptoms. In this review, we will comment on the challenges encountered when managing patients with DMGP and provide an update on advances in drug development and endoscopic and surgical interventions.

Implication of neurohormonal-coupled mechanisms of gastric emptying and pancreatic secretory function in diabetic gastroparesis

Recently, diabetic gastroparesis (DGP) has received much attention as its prevalence is increasing in a dramatic fashion and management of patients with DGP represents a challenge in the clinical practice due to the limited therapeutic options. DGP highlights an interrelationship between the gastric emptying and pancreatic secretory function that regulate a wide range of digestive and metabolic functions, respectively. It well documented that both gastric emptying and pancreatic secretion are under delicate control by multiple neurohormonal mechanisms including extrinsic parasympathetic pathways and gastrointestinal (GI) hormones. Interestingly, the latter released in response to various determinants that related to the rate and quality of gastric emptying. Others and we have provided strong evidence that the central autonomic nuclei send a dual output (excitatory and inhibitory) to the stomach and the pancreas in response to a variety of hormonal signals from the abdominal viscera. Most of these hormones released upon gastric emptying to provide feedback, and control this process and simultaneously regulate pancreatic secretion and postprandial glycemia. These findings emphasize an important link between gastric emptying and pancreatic secretion and its role in maintaining homeostatic processes within the GI tract. The present review deals with the neurohormonal-coupled mechanisms of gastric emptying and pancreatic secretory function that implicated in DGP and this provides new insights in our understanding of the pathophysiology of DGP. This also enhances the process of identifying potential therapeutic targets to treat DGP and limit the complications of current management practices.

Neutrophils injure gallbladder interstitial Cajal-like cells in a guinea pig model of acute cholecystitis

Acute cholecystitis is a common disease with gallbladder dysmotility. Disease pathogenesis involves immune cell infiltration as well as changes in gallbladder interstitial Cajal-like cells (ICLCs). However, it remains unclear if or how the immune cells affect ICLC morphology, density, distribution, and function in gallbladder tissue during acute cholecystitis. In this study, we explored the acute cholecystitis-related alterations in gallbladder ICLCs in a guinea pig model, focusing on the effects of neighboring neutrophils. Adult guinea pigs were randomly divided into four groups (control, 24 hr common bile duct ligation [CBDL], 48-hr CBDL, and antipolymorphonuclear neutrophil [PMN] treated) and analyzed using methylene blue staining and immunofluorescence. Gallbladder contractility was also monitored. To culture gallbladder ICLCs, collagenase digestion was performed on tissue from 10- to 15-day-old guinea pigs. Neutrophils isolated from the peripheral blood of experimental animals 48-hr postsurgery were also cocultured with the gallbladder ICLCs. Intracellular calcium was detected with Fluo-4 AM dye. Our results showed that gallbladder ICLC density significantly declined during acute cholecystitis and was accompanied by shortening of the cellular processes and damage to their network-like structure. However, pretreatment with anti-PMN partially prevented these changes. Gallbladder contraction was also significantly decreased during acute cholecystitis, and this appeared to be mediated by the neutrophils. Moreover, ICLCs cocultured with neutrophils also had shortened and reduced processes and impaired network-like structure formation. Intracellular calcium transient was less sensitive to contraction agonists and inhibitors when cocultured with neutrophils. Taken together, neutrophils greatly affect gallbladder ICLCs and dysmotility during acute cholecystitis.

Electroacupuncture at ST-36 Protects Interstitial Cells of Cajal via Sustaining Heme Oxygenase-1 Positive M2 Macrophages in the Stomach of Diabetic Mice

Background

Electroacupuncture (EA) at ST-36 has been reported to improve delayed gastric emptying and protect the networks of ICC in diabetic models. However, the mechanisms of the effects of EA are still unclear. The purpose of this study was to investigate whether the HO-1 positive M2 macrophages participate in the protective effects of EA for the ICC networks.

Methods

Male C57BL/6 mice were randomized into five groups: the normal control group, diabetic group (DM), diabetic mice with sham EA group (SEA), diabetic mice with low frequency EA group (LEA), and diabetic mice with high frequency EA group (HEA). ICC network changes were detected by Ano1 immunostaining. F4/80 and HO-1 costaining was used to measure HO-1 positive macrophage expression. Western blot and PCR methods were applied to monitor HO-1, IL-10, and macrophage markers, respectively. The serum MDA levels were detected by a commercial kit.

Results

This study presents the following results: (1) Compared with the control group, ICC networks were severely disrupted in the DM group, but no obvious changes were found in the LEA and HEA groups. (2) Many HO-1 positive macrophages could be observed in the LEA and HEA groups, and the expression of HO-1 was also markedly upregulated. (3) The IL-10 expression was obviously upregulated in the LEA and HEA groups. (4) The serum MDA levels were decreased in the real EA group. (5) When compared to the DM group, the expression of CD163 and Arg-1 was increased in the LEA and HEA groups, but the iNOS expression was decreased.

Conclusion

The protective effects of EA on the networks of ICC may rely on the HO-1 positive macrophages to mediate anti-inflammatory and antioxidative stress effects.

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

BACKGROUND

The molecular changes that occur in the stomach that are associated with idiopathic gastroparesis are poorly described. The aim of this study was to use quantitative analysis of mRNA expression to identify changes in mRNAs encoding proteins required for the normal motility functions of the stomach.

METHODS

Full-thickness stomach biopsy samples were collected from non-diabetic control subjects who exhibited no symptoms of gastroparesis and from patients with idiopathic gastroparesis. mRNA was isolated from the muscularis externa and mRNA expression levels were determined by quantitative reverse transcriptase (RT)-PCR.

KEY RESULTS

Smooth muscle tissue from idiopathic gastroparesis patients had decreased expression of mRNAs encoding several contractile proteins, such as MYH11 and MYLK1. Conversely, there was no significant change in mRNAs characteristic of interstitial cells of Cajal (ICCs) such as KIT or ANO1. There was also a significant decrease in mRNA-encoding platelet-derived growth factor receptor α (PDGFRα) and its ligand PDGFB and in Heme oxygenase 1 in idiopathic gastroparesis subjects. In contrast, there was a small increase in mRNA characteristic of neurons. Although there was not an overall change in KIT expression in gastroparesis patients, KIT expression showed a significant correlation with gastric emptying whereas changes in MYLK1, ANO1 and PDGFRα showed weak correlations to the fullness/satiety subscore of patient assessment of upper gastrointestinal disorder-symptom severity index scores.

CONCLUSIONS AND INFERENCES

Our findings suggest that idiopathic gastroparesis is associated with altered smooth muscle cell contractile protein expression and loss of PDGFRα⁺ cells without a significant change in ICCs.

Mild diabetes: long-term effects on gastric motility evaluated in rats

Moderate hyperglycaemic levels seem to be related to abnormal gastric motility in diabetes mellitus. However, experimental models designed to evaluate the relationship between motility and diabetes over time are not yet well established. Our objective was to investigate the long-term effects of mild diabetes on gastric motility in rats. Newborn male rats received streptozotocin (mild diabetes groups - MD) or vehicle (control groups - C), and both groups were evaluated after 3 (C3 and MD3) and 6 months (C6 and MD6) postinduction. Mild diabetic animals (MD3 and MD6) showed moderately elevated blood glucose and decreased insulin levels compared with control (C3 and C6). Insulin secretion was enhanced in MD6 compared with MD3, most likely due to partial β-cell regeneration indicated by HOMA-β. In HOMA-IR, it was noticed that MD6 animals had impaired insulin response compared with MD3. Gastric emptying was faster, amplitude of contraction was stronger in MD6 compared with MD3, and in both groups, the differences were significant when compared with control animals. A significant abnormal rhythmic index was calculated for the mild diabetic groups, despite unchanged mean frequency of contraction. In conclusion, despite increased insulin levels over time, constant levels of moderate hyperglycaemia are also related to abnormal gastric motility and impairment of gastric function.

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.