Mechanisms Of Mucosal Protection Research Articles

Effects of Feed Supplementation With Fulvic Acid on the Systemic and Mucosal Protective Mechanisms of Juvenile Rainbow Trout (Oncorhynchus mykiss).

Rainbow trout (Oncorhynchus mykiss) is an important fish species raised in aquaculture, but it is susceptible to stress, infections diseases. The present study aimed to determine the effects of fulvic acid feed addition on the systemic and mucosal protective mechanisms of juvenile rainbow trout and to elucidate the underlying molecular mechanisms of changes in the gut. Rainbow trout (4.30 ± 0.6 g) diet was supplemented with different levels of fulvic acid: 0% (Control), 0.5%, 1% and 2%. At the end of 8-week feeding trial, growth parameters such as final weight gained weight (%), SGR (F1%) increased, and FCR (all levels) decreased significantly compared to the control group. We found that the activity of lysozyme, glutathione peroxidase, and catalase in the serum were significantly improved, especially after the addition of 0.5% and 1% of fulvic acid. At the same time, the immunoglobulin concentration in the skin mucus was increased with 0.5% supplementation. However, the expression of tnf-α, il-6 and gpx in the intestine was strongly upregulated after supplementation with 2%, indicating oxidative stress and inflammation with this level of fulvic acid inclusion. Furthermore, the mucus lysozyme activity was reduced at this concentration, which can increase the susceptibility to pathogen invasion. The results suggest that adding 0.5%-1% of fulvic acid to the feed of juvenile rainbow trout can help to improve their immune and antioxidative defenses and thereby support the wellbeing of fish.

Gastroduodenal injury and repair mechanisms.

Although the mucosal barrier serves as a primary interface between the environment and host, little is known about the repair of acute, superficial lesions or deeper, persistent lesions that if not healed, can be the site of increased permeability to luminal antigens, inflammation, and/or neoplasia development. Studies on acute superficial lesions have been sparse in the past year, with more focus given to novel mechanisms of mucosal protection, and the way in which mature epithelial cells or committed stem cells dedifferentiate, reprogram, proliferate, and then regenerate the gastroduodenal mucosa after injury. For this, adenoviral therapy showed organ specific targeting with mRNA and protein expression of effectors to protect against mucosal injury and ulceration. A large database of plant-based agents known to protect against injury and ulceration was published, along with studies using plant-based compounds delivered with alginates, polysaccharide/gel floating rafts, or incorporated into nanoparticles or green carbon dots to improve targeting and retention at the ulcerated lesion. With RNA technology developing rapidly, particularly single-cell RNA sequencing, important and novel data was forthcoming on mucosal regeneration. In particular, the role of interleukin-17 hub proteins in mucosal healing was highlighted. The presence and role of injury reserve cells was determined, as was the composition of ligand gradients for cell differentiation in both stomach and duodenum. The role of amphiregulin in parietal cell differentiation from lineage-restricted stem cells and the Yap1 gene signature in metaplasia vs. healing ulcers were of particular importance. Additionally, studies unveiled the important role of mesenchymal stromal cells in differentiation and repair mechanisms, in Muse cells as an exciting new therapy for mucosal repair after injury, and the role of sympathetic neurons in activating the immune system to regulate mucosal repair mechanisms. Recent studies highlight novel mechanisms that promote mucosal regeneration after injury of the gastroduodenal mucosa.

Impact of Helicobacter pylori Eradication on Surgical Treatment of Peptic Ulcer Disease: Systematic Review.

Peptic ulcer disease (PUD) poses a significant global healthcare challenge, with an intricate interplay between stomach acid-pepsin levels and mucosal protective mechanisms. The emergence of Helicobacter pylori (H. pylori) as a major etiological factor revolutionized the therapeutic landscape, highlighting the importance of bacterial eradication in PUD management. Surgical intervention remains vital, particularly in cases of perforated peptic ulcers, despite a shift towards conservative approaches. Understanding the impact of H. pylori eradication on surgical outcomes is crucial for optimizing PUD management. This systematic review was conducted to assess how H. pylori eradication treatment impacts surgical results in patients with PUD. The criteria for inclusion involved research studies on individuals aged 18 years and older with a diagnosis of PUD that necessitated surgical treatment. Important results comprised eradication rates, complications after surgery, recurrence rates, and overall outcomes for patients. Two researchers independently screened and extracted data from electronic databases using a thorough search strategy. The evaluation of quality employed standardized instruments for randomized controlled trials and cohort studies. Nine research projects met the requirements for inclusion, offering information on the effectiveness of H. pylori elimination treatment on surgical results. Different rates of eradication were noted, with a notable number of patients experiencing postoperative complications. Recurrence of ulcers was a concern, despite treatment, emphasizing the complexity of PUD management. Studies have shown that eradication therapy is effective in certain patient groups, like young men with perforated peptic ulcers. Still, there are obstacles, especially for patients who test negative for H. pylori and experience recurring ulcers.The integration of H. pylori eradication with surgical intervention represents a holistic approach to PUD management. Although eradication therapy has the potential to enhance surgical results, difficulties remain, requiring personalized treatment approaches that consider patients' unique characteristics and the cause of the disease. This research adds to the growing knowledge of PUD treatment, stressing the importance of proper management.

Costunolide ameliorates MNNG-induced chronic atrophic gastritis through inhibiting oxidative stress and DNA damage via activation of Nrf2

BackgroundChronic atrophic gastritis (CAG) is a chronic digestive disease. Modern research has revealed substantial evidence indicating that the progression of CAG is closely linked to the occurrence of oxidative stress-induced DNA damage and apoptosis in the gastric mucosa. Additionally, research has indicated that Costunolide (COS), the primary active compound found in Aucklandiae Radix, a traditional herb, exhibits antioxidant properties. Nevertheless, the therapeutic potential of COS in treating CAG and its molecular targets have not yet been determined. PurposeThe objective of this research was to explore the potential gastric mucosal protective effects and mechanisms of COS against N-Methyl-N´-nitro-N-nitrosoguanidine (MNNG)-induced CAG. MethodsFirstly, the MNNG-induced rat CAG model was established in vivo. Occurrence of CAG was detected through macroscopic examination of the stomachs and H&E staining. Additionally, we assessed oxidative stress, DNA damage, and apoptosis using biochemical detection, Western blot, immunohistochemistry and immunofluorescence. Then, an in vitro model was developed to induce MNNG-induced damage in GES-1 cells, and the occurrence of cell damage was determined by Hoechst 33,342 staining and flow cytometry. Finally, the key targets of COS for the treatment of CAG were identified through molecular docking, cellular thermal shift assay (CETSA), and inhibitor ML385. ResultsIn vivo studies demonstrated that COS promotes the expression of Nrf2 in gastric tissues. This led to an increased expression of SOD, GSH, HO-1, while reducing the production of MDA. Furthermore, COS inhibited DNA damage and apoptosis by suppressing the expression of γH2AX and PARP1 in gastric tissues. In vitro studies showed that COS effectively reversed apoptosis induced by MNNG in GES-1 cells. Additionally, COS interacted with Nrf2 to promote its expression. Furthermore, the expression levels of SOD, GSH, and HO-1 were augmented, while the generation of ROS and MDA was diminished. ConclusionsOur results indicate that COS exhibits therapeutic effects on CAG through the promotion of Nrf2 expression and inhibition of oxidative stress and DNA damage. Therefore, COS has the potential to provide new drugs for the treatment of CAG.

Bowman's layer transplantation—A new hope for regaining of correct ocular surface

Aims/Purpose: To present a novel surgical technique of selective Bowman's layer transplantation as well as results of the surgery in patients with neurotrophic corneal ulcers.Methods: 3 eyes from 3 patients with neurotrophic corneal ulcers who underwent corneal grafting with Bowman's layer. Pre‐ and postoperative analyses of the anterior segment of the eye were based on optical coherence tomography and slit lamp assessment.Results: Postoperatively a gradual corneal stroma restoration and fast corneal epithelialisation were noticed.Conclusions: Based on our observations, stiff and firm structure of Bowman's layer is supposed to strengthen corneal surface and maintain its shape. It acts also as an anti‐pathogen and anti‐toxin corneal barrier. Application of this acellular corneal layer transplantation to cover trophic corneal ulcers is an interesting, modern and crucial method of neurotrophic keratitis treatment.Reference1. Hsu HY, Modi D. Etiologies, quantitative hypoesthesia, and clinical outcomes of neurotrophic keratopathy. Eye Contact Lens 2015;41(5):314–7.2. Sacchetti M, Lambiase A. Diagnosis and management of neurotrophic keratitis. Clin Ophthalmol 2014;8:571–9.3. Mantelli F, Mauris J, Argüeso P. The ocular surface epithelial barrier and other mechanisms of mucosal protection: from allergy to infectious diseases. Curr Opin Allergy Clin Immunol. 2013 Oct;13(5): 563–8.4. Wilson SE. Bowman's layer in the cornea‐ structure and function and regeneration. Exp Eye Res 2020 Jun;195:108033.5. Lagali N, Germundsson J, Fagerholm P. The Role of Bowman's Layer in Corneal Regeneration after Phototherapeutic Keratectomy: A Prospective Study Using In Vivo Confocal Microscopy. Invest Ophthalmol Vis Sc. 2009 Sep;50(9):4192–8.

Green carbon dots derived from Atractylodes macrocephala: A potential nanodrug for treating alcoholic gastric ulcer.

Alcoholic gastric ulcer is a common acute gastric injury disease. The drugs currently used in clinical practice not only cannot fundamentally treat gastric injury, but also have serious side effects. There is an urgent demand for the discovery of a mild drug to treat alcoholic gastric ulcers. Herein, the green carbon dots derived from charred Atractylodes macrocephala (CAM-CDs) were acquired and have been proven to be safe and effective in alleviating alcoholic gastric ulcers at an inhibition rate up to 60%. CAM-CDs can markedly attenuate the gastric mucosa damage such as mucosal defect, bleeding and inflammatory cell infiltration by histopathological examination. Serum and tissue inflammatory cytokine measurements, as well as immunohistochemistry results, indicate that its mechanism of gastric mucosal protection may involve the reduction of IL-1β and TNF-α by regulating inflammatory signaling pathway of the NF-κB/NLRP3 axis, as well as elevation of IL-10 levels. CAM-CDs also can reduce oxidative stress markers (MDA), increase PGE2 and mucin secretion (MUC5AC), and it simultaneously exerts slight inhibition of hydrogen potassium ATPase and pepsin activity to protect gastric mucosa, as well as increases the microbial diversity and regulates species composition of gut microbiota in rats with gastric ulcer. Our work provides a new perspective on utilizing carbon-based nanomaterials in the development of new mild drugs.

The Review of Domestic Research on Traditional Korean Medicine for Gastroesophageal Reflux Disease

This study was conducted to examine the current status of traditional korean medicine studies on gastroesophageal reflux disease in Korea, identify deficiencies, and suggest the direction of future medicine research methods to lay the foundation for traditional korean medicine treatment. All domestic papers on the korean traditional treatment of gastroesophageal reflux disease were selected among the literature published until August 2022 in six domestic databases. A total of 52 selected research data were classified into experimental research papers, clinical research papers, and review papers. In experimental papers, to evaluate the effectiveness of treatment, improvement of esophageal mucosal lesions, anti-inflammatory mechanisms, antioxidant mechanisms, esophageal mucosal protection mechanisms, gastric peristalsis control, and gastric acid secretion inhibition mechanisms were used as evaluation measures. In the clinical research paper, the basis for diagnosis of cases was clinical symptoms through medical history listening and diagnosis through visits to hospitals in the past. The average treatment period was 40.7 days, and the duration of treatment was not significantly affected by the duration of the disease. The most widely used Korean medicine treatment intervention was herbal medicine. There were 3 literature review studies, 3 systematic literature review and meta-analysis studies, 1 comparative review study for clinical trial guideline development, all using Chinese papers. This study included all domestic papers on gastroesophageal reflux disease to identify the research trend of the Korean oriental medicine community, and based on this, it is meaningful to confirm areas that need to be supplemented in future research plans.

Effect of Two Mucoprotectants, Gelatin Tannate and Xyloglucan plus Gelatin, on Cholera Toxin-Induced Water Secretion in Rats

Background: Newer antidiarrheal agents include the mucoprotectants gelatin tannate and xyloglucan. Methods: Rat models of cholera toxin (CT)-induced water secretion were used to evaluate the mucoprotective effects of gelatin tannate, xyloglucan, and related compounds. Results: Oral pretreatment for 4 days with gelatin tannate (250 and 500 mg/kg/day), but not tannic acid or gelatin (both 125 mg/kg/day), blocked CT-induced intestinal water secretion. CT-induced intestinal water secretion was also attenuated by oral xyloglucan 12.5 mg/kg + gelatin 125 mg/kg (6 h pre-CT) and gelatin 250 mg/kg (12 h pre-CT), and by local (intra-jejunal loop) administration of gelatin, gelatin tannate and xyloglucan concomitantly with CT. Conclusions: Gelatin tannate and xyloglucan + gelatin attenuated CT-induced intra-loop water secretion in this experimental model, supporting previous evidence that their mechanisms of mucosal protection are closely related to their chemical structures, which confer film-forming properties via the formation of mucoadhesive films.

Gastrokine 2 Regulates the Antitumor Effect of JAK2/STAT3 Pathway in Gastric Cancer.

GKN2 (gastrokine 2) mainly plays a regulatory role in gastric mucosal defense and cell protection mechanisms, and its role in gastric cancer has not been thoroughly elucidated. Immunohistochemistry was used to detect GKN2 and TFF1 expressions in 90 gastric cancer tissues, 48 neoplastic resection margins, and 22 normal gastric mucosa epithelia. It showed that the downregulation of GKN2 and TFF1 expressions in gastric cancer tissues was significantly different from that in adjacent normal gastric tissues and distal gastric mucosal tissues. Nevertheless, correlation analysis showed that GKN2 expression in gastric cancer tissues was independent of TFF1 expression. After overexpression of GKN2 was constructed in human gastric cancer cell line MKN28 with the Ad-GFP-GKN2 transfected, cell viability was measured by CCK-8 assay, and migration and invasion ability were analyzed by transwell migration assay and transwell invasion assay. It indicated that overexpression of GKN2 significantly reduced the viability of MKN28 and SGC7901 cells. Overexpression of GKN2 could also inhibit the migration and invasion ability in MKN28 and SGC7901 cells. In addition, upregulation of GKN2 can inactivate the JAK2/STAT3 pathway. Our data suggest that GKN2 and TFF1 play the antitumor role in gastric carcinoma, and TFF1 may not interact or cooperate with GKN2. GKN2 overexpression can inhibit the growth and metastasis by downregulating the JAK2/STAT3 pathway in gastric cancer cells.

Protection against SARS-CoV-2 infection by a mucosal vaccine in rhesus macaques.

Effective SARS-CoV-2 vaccines are urgently needed. Although most vaccine strategies have focused on systemic immunization, here we compared the protective efficacy of 2 adjuvanted subunit vaccines with spike protein S1: an intramuscularly primed/boosted vaccine and an intramuscularly primed/intranasally boosted mucosal vaccine in rhesus macaques. The intramuscular-alum–only vaccine induced robust binding and neutralizing antibody and persistent cellular immunity systemically and mucosally, whereas intranasal boosting with nanoparticles, including IL-15 and TLR agonists, elicited weaker T cell and Ab responses but higher dimeric IgA and IFN-α. Nevertheless, following SARS-CoV-2 challenge, neither group showed detectable subgenomic RNA in upper or lower respiratory tracts versus naive controls, indicating full protection against viral replication. Although mucosal and systemic protective mechanisms may differ, results demonstrate both vaccines can protect against respiratory SARS-CoV-2 exposure. In summary, we have demonstrated that the mucosal vaccine was safe after multiple doses and cleared the input virus more efficiently in the nasal cavity and thus may act as a potent complementary reinforcing boost for conventional systemic vaccines to provide overall better protection.

Protective effect and mechanisms of action of Mongolian medicine Sulongga-4 on pyloric ligation-induced gastroduodenal ulcer in rats.

BACKGROUNDSulongga-4 (SL-4) is a herbal formula used in traditional Mongolian medical clinics for the treatment of peptic ulcers and gastroenteritis, even though its pharmacological mechanism has not been well characterized.AIMTo evaluate the protective effect and identify the mechanisms of action of SL-4 on gastroduodenal ulcer induced by pyloric ligation (PL) in rats.METHODSPL was performed to induce gastric and duodenal ulcers in rats, which were then treated with oral SL-4 (1.3, 2.6, or 3.9 g/kg per day) for 15 d. PL-induced gastroduodenal ulceration. Therapeutic effects were characterized by pathological and histological evaluations and inflammatory indicators were analyzed by enzyme-linked immunosorbent assay. Microarray analyses were conducted to identify gene expression profiles of gastroduodenal tissue in PL rats with or without SL-4 treatment. The candidate target genes were selected and verified by quantitative reverse transcription polymerase chain reaction (qRT-PCR).RESULTSSL-4 decreased histopathological features in the PL-induced ulcerated rats. SL-4 significantly (P < 0.05) decreased expression of tumor necrosis factor-α, interleukin (IL)-1β, IL-6, endotoxin, platelet-activating factor, and increased prostaglandin E2 and epidermal growth factor in ulcer tissue. Microarray analysis was used to identify a panel of candidate target genes for SL-4 acting on PL-induced ulceration. Genes included some complement and coagulation cascade and retinol metabolism pathways that are closely associated with inflammatory responses and gastric mucosal protective mechanisms. qRT-PCR showed that altered expression of the selected genes, such as CYP2b2, UGT2b1, A2m, and MASP1 was consistent with the microarray results.CONCLUSIONSL-4 exerts protective effects against PL-induced gastroduodenal ulcers via reducing inflammatory cytokines and elevating expression of gastric acid inhibitory factors. Downregulation of CYP2b2 and UGT2b1 genes in retinol metabolism and upregulation of A2m and MASP1 genes in the complement and coagulation cascades pathways are possibly involved in SL-4-mediated protection against gastroduodenal ulcer.

The esophageal mucosal barrier in health and disease: mucosal pathophysiology and protective mechanisms.

Diseases of the esophagus, such as gastroesophageal reflux (GER), can result in changes to mucosal integrity, neurological function, and the microbiome. Although poorly understood, both age and GER can lead to changes to the enteric nervous system. In addition, the esophagus has a distinct microbiome that can be altered in GER. Mucosal integrity is also at risk due to persistent damage from acid. Diagnostic tools, such as ambulatory pH/impedance testing and esophageal mucosal impedance, can assess short-term and longitudinal GER burden, which can also assess the risk for mucosal compromise. The quality of the mucosal barrier is determined by its intercellular spaces, tight junctions, and tight junction proteins, which are represented by claudins, occludins, and adhesion molecules. Fortunately, there are protective factors for mucosal integrity that are secreted by the esophageal submucosal mucous glands and within saliva that are augmented by mastication. These protective factors have potential as therapeutic targets for GER. In this article, we aim to review diagnostic tools used to predict mucosal integrity, aging, and microbiome changes to the esophagus and esophageal mucosal defense mechanisms.

Roles of Up-Regulated Expression of ASIC3 in Sex Difference of Acid-Induced Duodenal HCO3 - Responses.

Although the morbidity of ulcers is statistically higher in males than females, the mechanism of this difference remains unknown. Recent studies show that duodenal HCO3 - response to mucosal acidification is higher in females than males, and this may be a factor responsible for the sex difference in the mucosal protective mechanisms. In this article, we examined the duodenal HCO3 - responses to various stimuli in male and female rats, including estrogen, and reviewed the mechanisms responsible for the sex difference in the acid-induced HCO3 - secretion. Mucosal acidification was performed by exposing the duodenum to 10 mM HCl for 10 min. PGE2 was administered intravenously, while capsaicin was applied topically to the duodenum for 10 min. Tamoxifen was given s.c. 30 min before the acidification. Ovariectomy was performed 2 weeks before the experiments; half of the animals were given estrogen i.m. after the operation. Mucosal acidification increased duodenal HCO3 - secretion in male rats, and this response was inhibited by indomethacin and sensory deafferentation. Although no sex difference was found in HCO3 - responses to PGE2 and capsaicin, the response to acid was significantly greater in female than male rats. The different HCO3 - response to acid disappeared on ovariectomy, and this effect was totally reversed by the repeated administration of estrogen. The gene expression of ASIC3 in female rats was greater than in male rats and down-regulated by ovariectomy or tamoxifen treatment in an estradiol- dependent manner, while no sex difference was observed in TRPV1 and CFTR expressions. In conclusion, the acid-induced HCO3 - response is greater in female than male rats, and this phenomenon is not due to changes in PGE2 sensitivity or TRPV1/CFTR expressions but may be accounted for by increased expression of ASIC3 on sensory neurons, which is associated with the chronic influence of estrogen.

Somatostatin receptor subtype 4 protects against indomethacin-induced gastrointestinal mucosal injury in mouse

Abstract Despite recent advancements in the pharmacologic and endoscopic management of gastrointestinal ulceration, it is still associated with high mortality. Therefore, it is important to understand mucosal protective mechanisms. Somatostatin, present in the endocrine cells &amp; sensory nerves, and its analogues reduce mucosal blood flow, pepsin and gastric acid secretion. Its receptor subtype 4 (sst4) mediates anti-inflammatory &amp; analgesic actions, as discovered by our group. Therefore, our aim was to investigate its role in gastrointestinal injury. We treated sst4 gene-deleted (sst4−/−) and wildtype mice with indomethacine (IDM; 35 mg/kg) or vehicle s.c.. Gastric &amp; small intestine lesions were evaluated after 4 &amp; 48 h macroscopically &amp; microscopically. Plasma protein extravasation &amp; myeloperoxidase (MPO) activity were assessed by ex vivo imaging, TNFα, IL-1, COX2, sst4 &amp; somatostatin mRNA levels by qPCR. Gastric (4h) and small intestinal macroscopic (24 h) lesions, MPO activity (24, 48 h), and plasma extravasation (30 min) were significantly greater in IDM-treated sst4−/− mice, while histopathological scores &amp; small intestinal length did not show strain difference. TNFα, IL-1, COX2 significantly upregulated after 4h in the stomach of sst4−/− mice, and the same pattern was observable in wildtype mice at later timepoint (48 h). These results provide evidence for the protective role of the sst4 receptor against IDM-induced gastrointestinal mucosal injury. This suggests the safety of sst4 agonist drug candidates in the gastrointestinal tract, and even their potential use for gastroprotective indication. Supported by: GINOP-2.3.2-15-2016-00050 – PEPSYS, GINOP-2.3.2 STAY ALIVE, EFOP-3.6.2-16-2017-00008, ÚNKP-19-3-III-PTE-211

Expression and Protective Functions of the sst4 Somatostatin Receptor in the Indomethacin‐Induced Gastrointestinal Mucosal Injury Model of the Mouse

IntroductionGastrointestinal ulceration is associated with high mortality despite advanced management, therefore, understanding of the mucosal protective mechanisms is important. Somatostatin is present in the endocrine cells and sensory nerves, and its analogues were shown to reduce mucosal blood flow, pepsin and gastric acid secretion. Our group discovered that its anti‐inflammatory and analgesic actions are exerted via the somatostatin receptor subtype 4 (sst4). Therefore, we investigated its expression and role in gastrointestinal injury.MethodsSst4 gene‐deleted (sst4−/−) and wildtype mice were treated s.c. with indomethacine (IDM; 35 mg/kg) or vehicle. RNA scope in situ hybridization was performed to localize, qPCR to quantify sst4 and somatostatin mRNA. Macroscopic and microscopic lesions in the stomach and small intestine were evaluated after 4 and 48 h. Plasma protein extravasation was measured by fluorescent, neutrophil myeloperoxidase (MPO) activity bioluminescent ex vivo imaging, TNFα, IL‐1 and COX2 mRNA by qPCR.ResultsSomatostatin mRNA is present in the neuroendocrine D‐cells and significantly upregulated 48 h after IDM. Sst4 mRNA in located in the myenteric plexus neurons, it’s expression did not change in response to mucosal injury.IDM‐induced gastric and small intestinal macroscopic lesions (4, 24 h), gastric MPO activity (24, 48 h) and plasma extravasation (30 min) were significantly greater in sst4−/− mice. TNFα, IL‐1, COX2 expressions significantly increased after 4 h in the stomach of sst4−/− mice, but in wild‐types the same pattern was observed only later, at the 48 h time‐point. IDM‐evoked histopathological alterations and small intestinal length reduction were not altered by the sst4 deletion.ConclusionThis is the first evidence for sst4 expression in myenteric plexus neurons and its protective roles against chemically‐induced gastrointestinal mucosal damage and inflammation. This suggests the safety of sst4 agonist drug candidates in the gastrointestinal tract, and even their potential use for gastroprotective indication.Support or Funding InformationSupported by: GINOP‐2.3.2‐15‐2016‐00050 – PEPSYS, GINOP‐2.3.2 STAY ALIVE, EFOP‐3.6.2‐16‐2017‐00008, ÚNKP‐19‐3‐III‐PTE‐211

Protective Role of the Somatostatin Receptor Subtype 4 in the Indomethacin‐Induced Gastrointestinal Mucosal Injury Model

Since gastrointestinal ulceration is still associated with high mortality despite advancements in the endoscopic and pharmacological management, precise understanding of the mucosal defensive and protective mechanisms is important. The neuropeptide somatostatin is present in the endocrine cells and sensory nerves, is analogues were shown to reduce mucosal blood flow, pepsin and gastric acid secretion. Its endocrine functions are mediated by the receptors sst2,3,5, and our group discovered that the anti‐inflammatory and analgesic actions are exerted via the sst4 receptor. Sst4 agonists are preclinically tested as novel drug candidates in theses areas. Therefore, we investigated the role of sst4 in gastrointestinal injury.Sst4 gene‐deleted (sst4 −/−) mice and wildtype counterparts (sst4 +/+) were treated s.c. with 35 mg/kg indomethacine (IDM) or its vehicle. Macroscopic and microscopic mucosal lesions in the stomach and small intestine were evaluated by the ImageJ program and semiquantitative histopathological scoring after 4 and 48 h, respectively. Small intestinal length, thymus, adrenal glands, spleen weight and plasma glucose levels were measured. Neutrophil myeloperoxidase (MPO) activity and plasma extravasation were measured by bioluminescent/fluorescent ex vivo imaging after 24 h.Macroscopic lesion area and MPO activity in the gastric mucosa were significantly greater in IDM‐treated sst4−/− mice than in wildtypes 4 h and 24 h after IDM administration, respectively. Similar tendency was observed in the duodenum and jejunum even after 48 h. However, IDM did not induce mucosal plasma extravasation in either group at the 24 h timepoint. Thymus weight was significantly less in sst4−/− mice than in sst4+/+ ones. Histopathological scores, small intestinal length, adrenal and spleen weight, and plasma glucose level were not altered by the sst4 deletion.These results provide evidence for a protective role of the sst4 receptor against chemical injury‐induced gastrointestinal mucosal damage. This shows the safety of sst4 agonist drug candidates in the gastrointestinal tract, and even highlights their potential use for gastroprotective indication.Support or Funding InformationGINOP‐2.3.2‐15‐2016‐00050 – PEPSYS, GINOP‐2.3.2 STAY ALIVE, EFOP‐3.6.2‐16‐2017‐00008, ÚNKP‐18‐3 New National Excellence Program of the Ministry of Human CapacitiesThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

ACVIM consensus statement: Support for rational administration of gastrointestinal protectants to dogs and cats.

The gastrointestinal (GI) mucosal barrier is continuously exposed to noxious toxins, reactive oxygen species, microbes, and drugs, leading to the development of inflammatory, erosive, and ultimately ulcerative lesions. This report offers a consensus opinion on the rational administration of GI protectants to dogs and cats, with an emphasis on proton pump inhibitors (PPIs), histamine type‐2 receptor antagonists (H2RAs), misoprostol, and sucralfate. These medications decrease gastric acidity or promote mucosal protective mechanisms, transforming the management of dyspepsia, peptic ulceration, and gastroesophageal reflux disease. In contrast to guidelines that have been established in people for the optimal treatment of gastroduodenal ulcers and gastroesophageal reflux disease, effective clinical dosages of antisecretory drugs have not been well established in the dog and cat to date. Similar to the situation in human medicine, practice of inappropriate prescription of acid suppressants is also commonplace in veterinary medicine. This report challenges the dogma and clinical practice of administering GI protectants for the routine management of gastritis, pancreatitis, hepatic disease, and renal disease in dogs and cats lacking additional risk factors for ulceration or concerns for GI bleeding. Judicious use of acid suppressants is warranted considering recent studies that have documented adverse effects of long‐term supplementation of PPIs in people and animals.

Similar and Distinct Mechanisms in the Protective Processes of Upper and Lower Gastrointestinal Tract.

Gastrointestinal (GI) mucosal integrity is based on the balance of aggressive and protective mechanisms. Mucosal damage may occur when the injurious factors become dominant or the mucosal defensive processes are impaired. The main target of the therapy against GI mucosal injury is the reduction of aggressive factors, however, the therapeutic possibilities for stimulation of mucosal defensive processes are rather limited. This overview focuses on the gastric and intestinal mucosal protective mechanisms and discusses the main targets that increase protective processes and increase the mucosal resistance to injurious stimuli at pre-epithelial, epithelial and sub-epithelial levels.

Thyroid hormones increase stomach goblet cell numbers and mucin expression during indomethacin induced ulcer healing in Wistar rats

BackgroundGastric ulcers are mucosal discontinuities that may extend into the mucosa, submucosa or even deeper. They result from an imbalance between mucosal aggressors and protective mechanisms that include the mucus bicarbonate layer. Thyroid hormones have been shown to accelerate gastric ulcer healing in part by increasing the adherent mucus levels. However, the effects of thyroid hormones on goblet cell numbers and expression of neutral and acidic mucins during ulcer healing have not been investigated.MethodsThirty six adult male Wistar rats were randomly divided into six groups each with six animals. Group 1 (normal control) and group 2 (negative control) were given normal saline for eight weeks. Groups 3 and 4 were given 100 μg/kg per day per os of thyroxine so as to induce hyperthyroidism. Groups 5 and 6 received 0.01% (w/v) Propylthiouracil (PTU) for 8 weeks so as to induce hypothyroidism. After thyroid hormonal levels were confirmed using radioimmunoassay and immunoradiometric assays, ulcer induction was done using 40 mg/kg intragastric single dose of Indomethacin in groups 2, 3 and 5. Stomachs were extracted after day 3 and 7 of ulcer induction for histological examination. Histochemistry was carried out using Periodic Acid Shiff and Alcian Blue. The number of acidic and neutral goblet cells were determined by counting numbers per field. Mucin expression (%) was determined using Quick Photo Industrial software version 3.1.ResultsThe numbers of neutral goblet cells (cells/field) increased significantly (P < 0.05) in the ulcer+thyroxine (14.67 ± 0.33), thyroxine (17.04 ± 1.71) and ulcer+PTU (12.89 ± 1.06) groups compared to the normal control (10.78 ± 1.07) at day 3. For the acidic goblet cells, differences between treatment groups were more pronounced at day 7 between the ulcer+thyroxine (22.56 ± 1.26) and thyroxine (22.89 ± 0.80). We further showed that percentage expression of both neutral and acidic mucins was significantly higher in the ulcer+thyroxine (9.23 ± 0.17 and 6.57 ± 0.35 respectively) and thyroxine groups (9.66 ± 0.21 and 6.33 ± 0.38 respectively) as compared to the normal control group (4.08 ± 0.20 and 4.38 ± 0.11 respectively) at day 3 after ulcer induction.ConclusionThis study confirms the role played by thyroid hormones in healing of indomethacin induced gastric ulcers. The study further demonstrates increased numbers of both neutral and acidic goblet cells and the increase in expression of both neutral and acidic mucins during healing of indomethacin induced ulcers.

The Role of the Polymeric Immunoglobulin Receptor and Secretory Immunoglobulins during Mucosal Infection and Immunity.

The gastrointestinal tract houses millions of microbes, and thus has evolved several host defense mechanisms to keep them at bay, and prevent their entry into the host. One such mucosal surface defense is the secretion of secretory immunoglobulins (SIg). Secretion of SIg depends on the polymeric immunoglobulin receptor (pIgR), which transports polymeric Ig (IgA or IgM) from the basolateral surface of the epithelium to the apical side. Upon reaching the luminal side, a portion of pIgR, called secretory component (SC) is cleaved off to release Ig, forming SIg. Through antigen-specific and non-specific binding, SIg can modulate microbial communities and pathogenic microbes via several mechanisms: agglutination and exclusion from the epithelial surface, neutralization, or via host immunity and complement activation. Given the crucial role of SIg as a microbial scavenger, some pathogens also evolved ways to modulate and utilize pIgR and SIg to facilitate infection. This review will cover the regulation of the pIgR/SIg cycle, mechanisms of SIg-mediated mucosal protection as well as pathogen utilization of SIg.