Gaseous Mediators in Gastrointestinal Mucosal Defense and Injury

Crucial role of carbon monoxide as a regulator of diarrhea caused by cholera toxin: Evidence of direct interaction with toxin

The present study evaluated the role of heme oxygenase 1 (HO-1)/carbon monoxide (CO) pathway in the cholera toxin-induced diarrhea and its possible action mechanism. The pharmacological modulation with CORM-2 (a CO donor) or Hemin (a HO-1 inducer) decreased the intestinal fluid secretion and Cl- efflux, altered by cholera toxin. In contrast, ZnPP (a HO-1 inhibitor) reversed the antisecretory effect of Hemin and potentiated cholera toxin-induced intestinal secretion. Moreover, CORM-2 also prevented the alteration of intestinal epithelial architecture and local vascular permeability promoted by cholera toxin. The intestinal absorption was not altered by any of the pharmacological modulators. Cholera toxin inoculation also increased HO-1 immunoreactivity and bilirubin levels, a possible protective physiological response. Finally, using fluorometric technique, ELISA assay and molecular docking simulations, we show evidence that CO directly interacts with cholera toxin, forming a complex that affects its binding to GM1 receptor, which help explain the antisecretory effect. Thus, CO is an essential molecule for protection against choleric diarrhea and suggests its use as a possible therapeutic tool.

Role of Hydrogen Sulfide in Inflammatory Bowel Disease

Hydrogen sulfide (H2S), originally known as toxic gas, has now attracted attention as one of the gasotransmitters involved in many reactions in the human body. H2S has been assumed to play a role in the pathogenesis of many chronic diseases, of which the exact pathogenesis remains unknown. One of them is inflammatory bowel disease (IBD), a chronic intestinal disease subclassified as Crohn's disease (CD) and ulcerative colitis (UC). Any change in the amount of H2S seems to be linked to inflammation in this illness. These changes can be brought about by alterations in the microbiota, in the endogenous metabolism of H2S and in the diet. As both too little and too much H2S drive inflammation, a balanced level is needed for intestinal health. The aim of this review is to summarize the available literature published until June 2023 in order to provide an overview of the current knowledge of the connection between H2S and IBD.

UPLC-QTOF-MS/MS-based metabolomic approach and gastroprotective effect of two chemotypes of Egletes viscosa (L.) less. against ethanol-induced gastric ulcer in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Egletes viscosa (L.) (macela) is a native wild herb that can be found in different states of northeastern Brazil. The infusions of its flower buds are traditionally used for the treatment of gastrointestinal disorders. E. viscosa possesses two chemotypes (named A and B), distinguishable by the composition of the essential oil from the flower buds. Although there are previous studies of the gastroprotective effect of the isolated constituents of E. viscosa, its infusions have not been investigated yet.

AIM OF THE STUDY

The present study aimed to evaluate and compare the chemical composition and the gastroprotective effect of flower bud infusions of E. viscosa from chemotype A (EVCA) and chemotype B (EVCB).

MATERIALS AND METHODS

Sixteen infusions were brewed with flower buds according to the traditional preparation mode and were analyzed through a UPLC-QTOF-MS/MS based metabolomic approach for determination of their metabolic fingerprints and quantification of bioactive compounds. Afterward, these data were analyzed by chemometric methods (OPLS-DA) for discrimination of the two chemotypes. Additionally, infusions of EVCA and EVCB (50, 100 and 200 mg/kg, p.o.) were evaluated on gastric ulcers induced by absolute ethanol (96%, 0.2 mL, p.o.) in mice. To elucidate the gastroprotective mechanisms, the effect of EVCA and EVCB on gastric acid secretion and gastric wall mucus was determined and the role of TRPV1 channels, prostaglandins, nitric oxide and K_ATP channels were assessed. Moreover, the oxidative stress-related parameters and the histological aspects of the stomach tissue were analyzed.

RESULTS

The chemotypes can be discriminated from each other using UPLC-QTOF-MS/MS chemical fingerprints. Both chemotypes presented similar chemical compositions, consisting basically of caffeic acid derivatives, flavonoids and diterpenes. The quantification of bioactive compounds demonstrated that chemotype A possesses more ternatin, tanabalin and centipedic than chemotype B. EVCA and EVCB (50, 100 and 200 mg/kg, p.o.) significantly decreased the severity of ethanol-induced gastric lesions, as shown by a reduction in histological alterations and leucocyte infiltration in gastric tissue. The gastroprotective mechanism of both infusions involves an antioxidant effect, maintenance of gastric mucus and reduction gastric secretion. Stimulation of endogenous prostaglandins and nitric oxide release, activation of TRPV1 channels, and K_ATP channels are also involved in the gastroprotection of the infusions.

CONCLUSION

The gastroprotective effect of EVCA and EVCB was equivalent and mediated through antioxidant and antisecretory actions, including the activation of TRPV1 receptors, stimulation of endogenous prostaglandins and nitric oxide, and opening of K_ATP channels. The presence of caffeic acid derivatives, flavonoids and diterpenes in both infusions is involved in mediating this protective effect. Our findings support the traditional use of infusions of E. viscosa for gastric disorders regardless of the chemotype.

The Protective Effect of Walnut Oligopeptides against Indomethacin-Induced Gastric Ulcer in Rats

The aim of this study was to investigate the potential protective effects of walnut oligopeptides (WOPs) on indomethacin-induced gastric ulcers in rats. The rats were divided into the following groups: normal group, model group, omeprazole group (0.02 g/kg), and WOPs groups (0.22, 0.44, and 0.88 g/kg, respectively). After receiving gavage once per day for 30 consecutive days, the rats were injected intraperitoneally with indomethacin 48 mg/kg to induce gastric ulcers. Then, the serum inflammatory cytokines and gastric prostaglandin E2 (PGE2), oxidative stress-related indicators, and the RNA expression of COX-1 and COX-2 were measured. The results revealed that WOPs confer significant gastroprotection on gastric ulcers caused by indomethacin, regulating inflammatory cytokines, oxidative stress, and prostaglandins synthesis, and enhancing the expression of COX-1 and COX-2 in gastric tissue, thus exerting its protective effect on gastric mucosa. The gastroprotective mechanism may be related to the involvement of the arachidonic acid metabolism and upregulation of tryptophan, phenylalanine, tyrosine, and alpha-Linolenic acid metabolism synthesis in vivo.

Potential effects of carbon monoxide donor and its nanoparticles on experimentally induced gastric ulcer in rats

The prevalence of gastric ulcers is increasing worldwide, especially those brought on by non-steroidal anti-inflammatory drugs (NSAIDS), so prevention is extremely crucial. The protective potential of carbon monoxide (CO) in several inflammatory disorders has been clarified. The goal of the current study was to investigate the gastroprotective effect of CO produced by its pharmacological donor (CORM2) and its nanoparticles (NPs) against indomethacin (INDO)-induced ulcers. Investigations on CORM2's dose-dependent effects were also conducted. For induction of gastric ulcer, 100 mg kg^-1 of INDO was given orally. Before ulcer induction, CORM2 (5, 10, and 15 mg kg^-1), CORM2 nanoparticles (5 mg kg^-1), or ranitidine (30 mg kg^-1) were given intraperitoneally for 7 days. Ulcer score, gastric acidity, gastric contents of malondialdehyde (MDA), nitric oxide (NO), heme oxygenase-1 (HO-1), and carboxyhemoglobin (COHb) blood content were estimated. Additionally, gene expression of nuclear factor erythroid 2-related factor 2 (NRF2) and immunohistochemical staining of cyclooxygenase-1 (COX-1) as well as cyclooxygenase-2 (COX-2) were analyzed. Results demonstrated a substantial dose-dependent decrease in ulcer score, pro-inflammatory indicators, and oxidative stress markers with CORM2 and its NPs. Furthermore, CORM2 and its NPs markedly increased NRF2, COX-1, and HO-1, but CORM2 NPs outperformed CORM2 in this regard. In conclusion, the CO released by CORM2 can protect against INDO-induced gastric ulcers dose dependently, and the highest used dose had no effect on COHb concentration.

Development of the PC-NSAID technology: From contact angle to Vazalore®

We describe strategies in drug development to reduce the gastrointestinal (GI) toxicity of nonsteroidal anti-inflammatory drugs (NSAIDs). We then provide an overview of the experiments that led to the development of PC-NSAIDs, a novel family of NSAIDs associated with phosphatidylcholine (PC) that have reduced GI toxicity and full therapeutic activity. Furthermore, we describe the evidence showing: that the stomach possesses hydrophobic properties that are attributable to phospholipids lining the mucus gel layer; and that NSAIDs chemically associate with intrinsic PC, thereby attenuating the tissue's hydrophobic properties. Further, pre-associating NSAIDs with PC reduces the GI toxicity of these drugs, both in rodent ulcer models and in human subjects, without affecting the drugs' therapeutic activity. Finally, we discuss the commercialization and launch of Aspirin-PC, an over-the-counter (OTC) drug with the brand name Vazalore®.

Hydrogen Sulfide Metabolizing Enzymes in the Intestinal Mucosa in Pediatric and Adult Inflammatory Bowel Disease

Hydrogen sulfide (H2S) is a toxic gas that has important regulatory functions. In the colon, H2S can be produced and detoxified endogenously. Both too little and too much H2S exposure are associated with inflammatory bowel disease (IBD), a chronic intestinal disease mainly classified as Crohn's disease (CD) and ulcerative colitis (UC). As the pathogenesis of IBD remains elusive, this study's aim was to investigate potential differences in the expression of H2S-metabolizing enzymes in normal aging and IBD. Intestinal mucosal biopsies of 25 adults and 22 children with IBD along with those of 26 healthy controls were stained immunohistochemically for cystathionine-γ-lyase (CSE), 3-mercapto-sulfurtransferase (3-MST), ethylmalonic encephalopathy 1 protein (ETHE1), sulfide:quinone oxidoreductase (SQOR) and thiosulfate sulfurtransferase (TST). Expression levels were calculated by multiplication of the staining intensity and percentage of positively stained cells. Healthy adults showed an overall trend towards lower expression of H2S-metabolizing enzymes than healthy children. Adults with IBD also tended to have lower expression compared to controls. A similar trend was seen in the enzyme expression of children with IBD compared to controls. These results indicate an age-related decrease in the expression of H2S-metabolizing enzymes and a dysfunctional H2S metabolism in IBD, which was less pronounced in children.

Effect of Calcium-Sulphate-Bicarbonate Water in a Murine Model of Non-Alcoholic Fatty Liver Disease: A Histopathology Study

The progression of nonalcoholic fatty liver disease (NAFLD) is associated with alterations of the gut–liver axis. The activation of toll-like receptor 4 (TLR4) pathways by endotoxins, such as lipopolysaccharide (LPS), contributes to liver injury. The aim of the present study was to evaluate the possible beneficial effects of a calcium-sulphate-bicarbonate natural mineral water on the gut–liver axis by evaluating liver and terminal ileum histopathology in a murine model of NAFLD. NAFLD was induced in mice by administrating a methionine-choline-deficient (MCD) diet. The following experimental groups were evaluated: controls (N = 10); MCD+Tap water (MCD; N = 10); MCD+Calcium-sulphate-bicarbonate water (MCD/W_csb; N = 10). Mice were euthanised after 4 and 8 weeks. Liver and terminal ileum samples were collected. Samples were studied by histomorphology, immunohistochemistry, and immunofluorescence. In mice subjected to the MCD diet, treatment with mineral water improved inflammation and fibrosis, and was associated with a reduced number of activated hepatic stellate cells when compared to MCD mice not treated with mineral water. Moreover, MCD/W_csb mice showed lower liver LPS localization and less activation of TLR4 pathways compared to the MCD. Finally, W_csb treatment was associated with improved histopathology and higher occludin positivity in intestinal mucosa. In conclusion, calcium-sulphate-bicarbonate water may exert modulatory activity on the gut–liver axis in MCD mice, suggesting potential beneficial effects on NAFLD.

Deletion of cystathionine-γ-lyase in bone marrow-derived cells promotes colitis-associated carcinogenesis

Ulcerative colitis (UC) is characterized by widespread relapsing inflammation of the colonic mucosa. Colitis-associated cancer (CAC) is one of the most serious complications of a prolonged history of UC. Hydrogen sulfide (H2S) has emerged as an important physiological mediator of gastrointestinal homeostasis, limiting mucosal inflammation and promoting tissue healing in response to injury. Inhibition of cystathionine-γ-lyase (CSE)-dependent H2S production in animal models of UC has been shown to exacerbate colitis and delay tissue repair. It is unknown whether CSE plays a role in CAC, or the downregulation of CSE expression and/or activity promotes CAC development. In humans, we observed a significant decrease in CSE expression in colonic biopsies from patients with UC. Using the dextran sodium sulfate (DSS) model of epithelium injury-induced colitis and global CSE KO mouse strain, we demonstrated that CSE is critical in limiting mucosal inflammation and stimulating epithelial cell proliferation in response to injury. In vitro studies showed that CSE activity stimulates epithelial cell proliferation, basal and cytokine-stimulated cell migration, as well as cytokine regulation of transepithelial permeability. In the azoxymethane (AOM)/DSS model of CAC, the loss of CSE expression accelerated both the development and progression of CAC. The increased tumor multiplicity and severity of CAC observed in CSE-KO mice were associated with reduced levels of mucosal IL-10 expression and increased levels of IL-6. Restoring CSE expression in bone marrow (BM) cells of CSE-KO mice through reciprocal BM transplantation raised mucosal IL-10 expression, decreased IL-6 level, and reduced the number of aberrant crypt foci and tumors in AOM/DSS-treated mice. These studies demonstrate that CSE expression in BM cells plays a critical role in suppressing CAC in mice. Furthermore, the data suggest that the inhibitory effects of CSE on the development of CAC are due, in part, to the modulation of mucosal pro-and anti-inflammatory cytokine expression.

Modulatory Role of Carbon Monoxide on the Inflammatory Response and Oxidative Stress Linked to Gastrointestinal Disorders

Significance: Carbon monoxide (CO) is an endogenous gaseous mediator that plays an important role in maintaining gastrointestinal (GI) tract homeostasis, acting in mucosal defense, and providing negative modulation of pathophysiological markers of clinical conditions. Recent Advances: Preclinical studies using animal models and/or cell culture show that CO can modulate the inflammatory response and oxidative stress in GI mucosal injuries and pathological conditions, reducing proinflammatory cytokines and reactive oxygen species, while increasing antioxidant defense mechanisms. Critical Issues: CO has potent anti-inflammatory and antioxidant effects. The defense mechanisms of the GI tract are subject to aggression by different chemical agents (e.g., drugs and ethanol) as well as complex and multifactorial diseases, with inflammation and oxidative stress as strong triggers for the deleterious effects. Thus, it is possible that CO acts on a variety of molecules involved in the inflammatory and oxidative signaling cascades, as well as reinforcing several defense mechanisms that maintain GI homeostasis. Future Directions: CO-based therapies are promising tools for the treatment of GI disorders, such as gastric and intestinal injuries, inflammatory bowel disease, and pancreatitis. Therefore, it is necessary to develop safe and selective CO-releasing agents and/or donor drugs to facilitate effective treatments and methods for analysis of CO levels that are simple and inexpensive. Antioxid. Redox Signal. 37, 98-114.

Carbon monoxide (CO)/heme oxygenase (HO)-1 in gastrointestinal tumors pathophysiology and pharmacology - possible anti- and pro-cancer activities

Gastrointestinal (GI) tract cancers pose a significant pharmacological challenge for researchers in terms of the discovery of molecular agents and the development of targeted therapies. Although many ongoing clinical trials have brought new perspectives, there is still a lack of successful long-term treatment. Several novel pharmacological and molecular agents are being studied in the prevention and treatment of GI cancers. On the other hand, pharmacological tools designed to release an endogenous gaseous mediator, carbon monoxide (CO), were shown to prevent the gastric mucosa against various types of injuries and exert therapeutic properties in the treatment of GI pathologies. In this review, we summarized the current evidence on the role of CO and heme oxygenase 1 (HO-1) as a CO producing enzyme in the pathophysiology of GI tumors. We focused on a beneficial role of HO-1 and CO in biological systems and common pathological conditions. We further discussed the complex and ambiguous function of the HO-1/CO pathway in cancer cells with a special emphasis on molecular and cellular pro-cancerous and anti-cancer mechanisms. We also focused on the role that HO-1/CO plays in GI cancers, especially within upper parts such as esophagus or stomach.

The Interaction of NO and H2S in Boar Spermatozoa under Oxidative Stress

Various recent studies dedicated to the role of nitric oxide (NO) and hydrogen sulfide (H2S) in somatic cells provide evidence for an interaction of the two gasotransmitters. In the case of male gametes, only the action of a single donor of each gasotransmitter has been investigated up until today. It has been demonstrated that, at low concentrations, both gasotransmitters alone exert a positive effect on sperm quality parameters. Moreover, the activity of gaseous cellular messengers may be affected by the presence of oxidative stress, an underlying condition of several male reproductive disorders. In this study, we explored the effect of the combination of two donors SNP and NaHS (NO and H2S donors, respectively) on boar spermatozoa under oxidative stress. We applied NaHS, SNP, and their combination (DD) at 100 nM concentration in boar spermatozoa samples treated with Fe2+/ascorbate system. After 90 min of incubation at 38 °C, we have observed that progressive motility (PMot) and plasma membrane integrity (PMI) were improved (p < 0.05) in DD treatment compared to the Ctr sample under oxidative stress (CtrOX). Moreover, the PMot of DD treatment was higher (p < 0.05) than that of NaHS. Similar to NaHS, SNP treatment did not overcome the PMot and PMI of CtrOX. In conclusion, for the first time, we provide evidence that the combination of SNP and NaHS surmounts the effect of single-donor application in terms of PMot and PMI in porcine spermatozoa under oxidative stress.

Microbiome Profile and Molecular Pathways Alterations in Gastrointestinal Tract by Hydrogen Sulfide-Releasing Nonsteroidal Anti-Inflammatory Drug (ATB-352): Insight into Possible Safer Polypharmacy

Aims: Nonsteroidal anti-inflammatory drugs, including ketoprofen, induce adverse effects within the gastrointestinal (GI)-tract. Hydrogen sulfide (H₂S) is an antioxidative gaseous mediator contributing to GI-protection. We aimed to evaluate the GI safety of a novel H₂S-releasing derivative of ketoprofen (ATB-352) versus classic ketoprofen and the molecular mechanisms of their activity after chronic treatment in experimental animal models. Results: Ketoprofen (10 mg/kg/day) administered intragastrically for 7 days in contrast with ATB-352 (14 mg/kg/day) reduced mucosal H₂S content inducing GI damage with significantly increased injury score, altered intestinal microbiome profile, and modulation of more than 50% of 36 investigated molecular sensors (e.g., mammalian target of rapamycin or suppressor of cytokine signaling 3 [SOCS3]). Polypharmacy with aspirin (10 mg/kg/day) enhanced ketoprofen toxicity not affecting GI safety of ATB-352. Omeprazole (20 mg/kg/day) decreased ketoprofen-induced injury to the level of ATB-352 alone. Both compounds combined or not with aspirin or omeprazole maintained the ability to inhibit cyclooxygenase (COX) activity manifested by decreased prostaglandin production. Innovation and Conclusions: Ketoprofen-induced H₂S-production decrease and intestinal microbiome profile alterations lead to GI toxicity observed on macro-/microscopic and molecular levels. Ketoprofen but not ATB-352 requires concomitant treatment with omeprazole to eliminate GI adverse effects. ATB-352 applied alone or in a polypharmacy setting with aspirin effectively inhibited COX and maintained GI safety due to H₂S-release. Neither compound affected DNA oxidation in the GI mucosa, but ATB-352 had lower impact on molecular oxidative/inflammatory response pathways and intestinal microbiome. The GI safety of ATB-352 could be due to the involvement of heme oxygenase 1 and SOCS3 pathway activation. Antioxid. Redox Signal. 36, 189-210.

Cytoprotective gastric pentadecapeptide BPC 157 resolves major vessel occlusion disturbances, ischemia-reperfusion injury following Pringle maneuver, and Budd-Chiari syndrome

The stable gastric pentadecapeptide BPC 157 counteracts various venous occlusion-induced syndromes. Summarized are all these arguments, in the Robert’s cytoprotection concept, to substantiate the resolution of different major vessel occlusion disturbances, in particular ischemia-reperfusion injury following the Pringle maneuver and Budd-Chiari syndrome, which was obtained by BPC 157 therapy. Conceptually, there is a new point, namely, endothelium maintenance to epithelium maintenance (the recruitment of collateral blood vessels to compensate for vessel occlusion and reestablish blood flow or bypass the occluded or ruptured vessel). In this paper, we summarize the evidence of the native cytoprotective gastric pentadecapeptide BPC 157, which is stable in the human gastric juice, is a membrane stabilizer and counteracts gut-leaky syndrome. As a particular target, it is distinctive from the standard peptide growth factors, involving particular molecular pathways and controlling VEGF and NO pathways. In the early 1990s, BPC 157 appeared as a late outbreak of the Robert’s and Szabo’s cytoprotection-organoprotection concept, like the previous theoretical/practical breakthrough in the 1980s and the brain-gut axis and gut-brain axis. As the time went on, with its reported effects, it is likely most useful theory practical implementation and justification. Meantime, several reviews suggest that BPC 157, which does not have a lethal dose, has profound cytoprotective activity, used to be demonstrated in ulcerative colitis and multiple sclerosis trials. Likely, it may bring the theory to practical application, starting with the initial argument, no degradation in human gastric juice for more than 24 h, and thereby, the therapeutic effectiveness (including via a therapeutic per-oral regimen) and pleiotropic beneficial effects.

VEGFR2 in vascular smooth muscle cells mediates H2S-induced dilation of the rat cerebral basilar artery

INTRODUCTION

The aim of present study was to study whether the vascular endothelial growth factor receptor 2 (VEGFR₂) mediates hydrogen sulfide (H₂S)-induced relaxation of the rat cerebral vasculature.

METHODS

Relaxation of cerebral basilar artery (CBA) and vascular smooth muscle cells (VSMCs) was measured by using a pressure myograph system and image analysis system, respectively. The intracellular calcium concentration ([Ca²⁺]_i) in VSMCs was detected using fluorescence imaging analysis.

RESULTS

We found that H₂S donor NaHS induced significant relaxation of VSMCs from the CBA of wild type rat, but in VEGFR₂ knockdown VSMCs, NaHS-induced relaxation reduced markedly. In addition, NaHS-induced vasodilation of rat CBA also attenuated obviously when the expression of VEGFR₂ was knocked down in vivo. In addition, pretreatment with the VEGFR₂ blocker SU5416 likewise lowered the NaHS-induced relaxation of rat CBA. Nevertheless, the VEGFR₂ agonist, vascular endothelial growth factor 164 (VEGF164), induced a concentration-dependent relaxation of CBA, which is similar to the effect of NaHS. Furthermore, we found that both NaHS and VEGF164 significantly inhibited the U₄₆₆₁₉-induced increase of [Ca²⁺]_i fluorescence intensity in the VSMCs. However, the inhibitory effect of NaHS on the [Ca²⁺]_i fluorescence intensity in VSMCs was markedly inhibited by pretreatment with SU5416 or VEGFR₂ knockdown.

CONCLUSION

These findings indicated that H₂S-induced CBA dilation and reduction of [Ca²⁺]_i in VSMCs occur by acting on VEGFR₂.

H2S Donors and Their Use in Medicinal Chemistry

Hydrogen sulfide (H2S) is a ubiquitous gaseous signaling molecule that has an important role in many physiological and pathological processes in mammalian tissues, with the same importance as two others endogenous gasotransmitters such as NO (nitric oxide) and CO (carbon monoxide). Endogenous H2S is involved in a broad gamut of processes in mammalian tissues including inflammation, vascular tone, hypertension, gastric mucosal integrity, neuromodulation, and defense mechanisms against viral infections as well as SARS-CoV-2 infection. These results suggest that the modulation of H2S levels has a potential therapeutic value. Consequently, synthetic H2S-releasing agents represent not only important research tools, but also potent therapeutic agents. This review has been designed in order to summarize the currently available H2S donors; furthermore, herein we discuss their preparation, the H2S-releasing mechanisms, and their -biological applications.

The Gastroprotective Effect of Naringenin against Ethanol-Induced Gastric Ulcers in Mice through Inhibiting Oxidative and Inflammatory Responses

Naringenin is a major flavanone found in grapes, tangelos, blood oranges, lemons, pummelo, and tangerines. It is known to have anti-inflammatory, antioxidant, anticancer, antimutagenic, antifibrogenic, and antiatherogenic pharmacological properties. This study aims to investigate the anti-inflammatory effects of naringenin in ethanol-induced gastric damage in vivo and ethanol-stimulated KATO III cells in vitro. Our results showed that pretreatment with naringenin significantly protected mice from ethanol-induced hemorrhagic damage, epithelial cell loss, and edema with leucocytes. It reduced gastric ulcers (GU) by suppressing ethanol-induced nuclear factor-κB (NF-κB) activity and decreasing the levels of nitric oxide (NO), malondialdehyde (MDA), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-8 (IL-8), and myeloperoxidase (MPO). In addition, pretreatment with naringenin might inhibit the secretion of TNF-α, IL-6, and IL-8, as well as the proteins cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) via the suppression of NF-κB and mitogen-activated protein kinase (MAPK) signaling in ethanol-stimulated stomach epithelial KATO III cells. Together, the results of this study highlight the gastroprotective effect of naringenin in GU of mice by inhibiting gastric secretion and acidity, reducing inflammation and oxidative stress, suppressing NF-κB activity, and restoring the histological architecture. These findings suggested that naringenin has therapeutic potential in the alleviation of ethanol-induced GU.

Protective effect of parecoxib sodium against ischemia reperfusion‑induced intestinal injury

Ischemia reperfusion (I/R)-induced intestinal injury is a pathophysiological process leading to oxidative stress and inflammatory responses, and revealing its underlying mechanisms is essential for developing therapeutic strategies. Cyclooxygenase (COX) has been reported to be involved in I/R injury. Parecoxib sodium, a selective inhibitor for COX-2, exerts protective effects, such as reducing I/R-induced injuries in the heart, kidney and brain. However, the potential role of parecoxib sodium in protecting the small intestine against I/R-induced injury has rarely been investigated. Therefore, the aim of the present study was to elucidate the effects and potential mechanisms of parecoxib sodium in I/R-induced intestinal injury. In total, 60 Sprague-Dawley rats were randomly divided into four groups: Control (sham operation) group, intestinal I/R group, 10 mg/kg parecoxib sodium-pre-treated I/R (I/R + Pare/10) group and the 20 mg/kg parecoxib sodium-pre-treated I/R (I/R + Pare/20) group. A regular I/R model was established to induce the intestinal injury in rats. Parecoxib sodium at 10 or 20 mg/kg was intraperitoneally administered into rats in both I/R + Pare groups once daily for 5 consecutive days prior to ischemia. Blood samples and small intestinal tissues were collected at 2 h after reperfusion. Changes in the levels of malondialdehyde, nitric oxide, interleukin (IL)-1β, IL-8, intercellular cell adhesion molecule-1 and IL-10, as well as the total antioxidant capacity were determined using ELISA, as were the activities of superoxidase dismutase and myeloperoxidase. Furthermore, the protein expression levels of total caspase-3, cleaved caspase-3, Bcl-2 and Bax were examined via western blot analysis. In addition, the daily survival rate post-reperfusion was examined for 7 days. It was revealed that parecoxib sodium increased the levels of antioxidants and suppressed the intestinal oxidative injury induced by I/R. Moreover, parecoxib sodium downregulated the expression levels of the proinflammatory factors, but upregulated the expression levels of anti-inflammatory factors. The results also demonstrated that parecoxib sodium attenuated I/R-induced apoptosis and increased the survival rate of rats. Thus, administration of parecoxib sodium prior to intestinal I/R attenuated intestinal injury and increased the rat survival rate by inhibiting I/R-induced inflammation, oxidative stress and apoptosis.

Low CBS expression can identify patients who benefit from adjuvant chemotherapy in gastric cancer

Aim: To explore the clinical significance of Cystathionine beta-synthase (CBS) expression in gastric cancer (GC).Research design and methods: CBS expression and clinicopathological/follow-up information of patients with gastric cancer undergoing operation were collected from The Cancer Genome Atlas (TCGA) database. The association of CBS expression with patients' overall survival (OS) was determined in the entire cohort and different subgroups. Validation was performed in two external cohorts from NCBI Gene Expression Omnibus (GEO) database. The estimated drug response of the tumors with different CBS expressions was characterized. The potential CBS-related cellular pathways in chemoresistance were explored.Results: High CBS was associated with poor OS in patients receiving adjuvant chemotherapy (ACT) but not those without ACT. And ACT was associated with favorable OS in patients with low CBS expression but not those with high CBS expression. The results were verified in two external cohorts. Drug response prediction suggested that patients with low CBS expression showed high sensitivity to 5-Fluorouracil. Gene Set Enrichment Analysis (GSEA) suggested that CBS might contribute to GC chemoresistance via modulating many cellular pathways, including down-regulating apoptosis and P53 pathways while up-regulating DNA repair pathway.Conclusion: Low CBS expression can predict the benefit from ACT in GC.

Gaseous Mediators as a Key Molecular Targets for the Development of Gastrointestinal-Safe Anti-Inflammatory Pharmacology

Non-steroidal anti-inflammatory drugs (NSAIDs) represent one of the most widely used classes of drugs and play a pivotal role in the therapy of numerous inflammatory diseases. However, the adverse effects of these drugs, especially when applied chronically, frequently affect gastrointestinal (GI) tract, resulting in ulceration and bleeding, which constitutes a significant limitation in clinical practice. On the other hand, it has been recently discovered that gaseous mediators nitric oxide (NO), hydrogen sulfide (H₂S) and carbon monoxide (CO) contribute to many physiological processes in the GI tract, including the maintenance of GI mucosal barrier integrity. Therefore, based on the possible therapeutic properties of NO, H₂S and CO, a novel NSAIDs with ability to release one or more of those gaseous messengers have been synthesized. Until now, both preclinical and clinical studies have shown promising effects with respect to the anti-inflammatory potency as well as GI-safety of these novel NSAIDs. This review provides an overview of the gaseous mediators-based NSAIDs along with their mechanisms of action, with special emphasis on possible implications for GI mucosal defense mechanisms.

Organic carbon monoxide prodrug, BW-CO-111, in protection against chemically-induced gastric mucosal damage

Metal-based carbon monoxide (CO)-releasing molecules have been shown to exert anti-inflammatory and anti-oxidative properties maintaining gastric mucosal integrity. We are interested in further development of metal-free CO-based therapeutics for oral administration. Thus, we examine the protective effect of representative CO prodrug, BW-CO-111, in rat models of gastric damage induced by necrotic ethanol or aspirin, a representative non-steroidal anti-inflammatory drug. Treatment effectiveness was assessed by measuring the microscopic/macroscopic gastric damage area and gastric blood flow by laser flowmetry. Gastric mucosal mRNA and/or protein expressions of HMOX1, HMOX2, nuclear factor erythroid 2-related factor 2, COX1, COX2, iNos, Anxa1 and serum contents of TGFB1, TGFB2, IL1B, IL2, IL4, IL5, IL6, IL10, IL12, tumor necrosis factor α, interferon γ, and GM-CSF were determined. CO content in gastric mucosa was assessed by gas chromatography. Pretreatment with BW-CO-111 (0.1 mg/kg, i.g.) increased gastric mucosal content of CO and reduced gastric lesions area in both models followed by increased GBF. These protective effects of the CO prodrug were supported by changes in expressions of molecular biomarkers. However, because the pathomechanisms of gastric damage differ between topical administration of ethanol and aspirin, the possible protective and anti-inflammatory mechanisms of BW-CO-111 may be somewhat different in these models.

Effects of drinking natural hydrogen sulfide (H2S) waters: a systematic review of in vivo animal studies

Natural waters containing originally hydrogen sulfide (H2S) gas with an S2-level at least 1 mg/L are classified as "sulfur waters" or "hydrogen sulfide waters." This systematic review aimed to evaluate in vivo experimental studies investigating the biological effects of natural H2S water drinking in healthy or with disease model laboratory animals. A comprehensive databases search (PubMed, Embase, Web of Science, and Google Scholar) was performed and PICOS criteria were used to assess eligibility. All relevant studies were identified, screened, and examined. The qualitative assessment was performed with the help of the SYRCLE Risk of Bias tool. A total of nine articles were included. The extracted data showed that ad libitum drinking of such waters by rats and mice exert beneficial effects on animal model of diabetes and glucose metabolism plus protective effects on diabetic cardiac, testicular, and nephrological complications as shown biochemically, histopathologically, and bio-molecularly. Additional effects were gastroprotection, antioxidant effects and improvement of intestinal physiology in healthy animals, reduction in general signs of murine model of colitis in mice, improvement in lipid metabolism and lipid-lowering effect, and positive interference with the enterohepatic cycle of the bile acids and biliary functions in hyperlipidemic rats. This systematic review provides preliminary insights into the "biological truth" about natural H2S waters and partly elucidates their potential therapeutic role in balneology and health resort medicine. However, it should be kept in mind that the retrieved preclinical data cannot be directly extrapolated to humans. Additionally, most of the included studies were rated for unclear risk of bias across all categories except random allocation, reflecting very poor reporting of methodological details. These limitations should be addressed when planning similar studies in the future. The question "can traditional hydropinic therapies or drinking cures with H2S waters at natural sulfur water spas/health resorts or natural (even artificial) H2S water consumption at home exert similar effects in humans?" remains to be clarified by clinical trials.

Evidence for Cytoprotective Effect of Carbon Monoxide Donor in the Development of Acute Esophagitis Leading to Acute Esophageal Epithelium Lesions

Exposure to acidic gastric content due to malfunction of lower esophageal sphincter leads to acute reflux esophagitis (RE) leading to disruption of esophageal epithelial cells. Carbon monoxide (CO) produced by heme oxygenase (HMOX) activity or released from its donor, tricarbonyldichlororuthenium (II) dimer (CORM-2) was reported to protect gastric mucosa against acid-dependent non-steroidal anti-inflammatory drug-induced damage. Thus, we aimed to investigate if CO affects RE-induced esophageal epithelium lesions development. RE induced in Wistar rats by the ligation of a junction between pylorus and forestomach were pretreated i.g. with vehicle CORM-2; RuCl₃; zinc protoporphyrin IX, or hemin. CORM-2 was combined with NG-nitro-L-arginine (L-NNA), indomethacin, capsazepine, or capsaicin-induced sensory nerve ablation. Esophageal lesion score (ELS), esophageal blood flow (EBF), and mucus production were determined by planimetry, laser flowmetry, histology. Esophageal Nrf-2, HMOXs, COXs, NOSs, TNF-α and its receptor, IL-1 family and IL-1 receptor antagonist (RA), NF-κB, HIF-1α, annexin-A1, suppressor of cytokine signaling (SOCS3), TRPV1, c-Jun, c-Fos mRNA/protein expressions, PGE₂, 8-hydroxy-deoxyguanozine (8-OHdG) and serum COHb, TGF-β1, TGF-β2, IL-1β, and IL-6 content were assessed by PCR, immunoblotting, immunohistochemistry, gas chromatography, ELISA or Luminex platform. Hemin or CORM-2 alone or combined with L-NNA or indomethacin decreased ELS. Capsazepine or capsaicin-induced denervation reversed CORM-2 effects. COHb blood content, esophageal HMOX-1, Nrf-2, TRPV1 protein, annexin-A1, HIF-1α, IL-1 family, NF-κB, c-Jun, c-Fos, SOCS3 mRNA expressions, and 8-OHdG levels were elevated while PGE₂ concentration was decreased after RE. CO donor-maintained elevated mucosal TRPV1 protein, HIF-1 α, annexin-A1, IL-1RA, SOCS3 mRNA expression, or TGF-β serum content, decreasing 8-OHdG level, and particular inflammatory markers expression/concentration. CORM-2 and Nrf-2/HMOX-1/CO pathway prevent esophageal mucosa against RE-induced lesions, DNA oxidation, and inflammatory response involving HIF-1α, annexin-A1, SOCS3, IL-1RA, TGF-β-modulated pathways. Esophagoprotective and hyperemic CO effects are in part mediated by afferent sensory neurons and TRPV1 receptors activity with questionable COX/PGE₂ or NO/NOS systems involvement.

The Gastroprotective Effect of Small Molecule Oligopeptides Isolated from Walnut (Juglans regia L.) against Ethanol-Induced Gastric Mucosal Injury in Rats

The study investigated the protective effect of walnut oligopeptides (WOPs) against ethanol-induced gastric injury using Sprague-Dawley (SD) rats. Rats were randomly divided into seven groups based on body weight (10/group), normal group, ethanol group, whey protein group (220 mg/kg body weight), omeprazole group (20 mg/kg body weight), and three WOPs groups (220, 440, 880 mg/kg body weight). After 30 days of treatment with WOPs, rats were given 5 mL/kg absolute ethanol by gavage to induce gastric mucosal injury. Gastric ulcer index (GUI) were determined and the following measured; gastric content pH, gastric mucin, endogenous pepsinogens (PG), prostaglandin E2 (PGE2), inflammatory cytokines, oxidative stress indicators, and the expression of apoptosis-related proteins were measured to evaluate the gastroprotective effect of WOPs. The results showed that the administration with WOPs markedly mitigated the hemorrhagic gastric lesions caused by ethanol in rats, and decreased the GUI, the gastric content pH, PG1, PG2, and NO levels, enhanced mucin and PGE2. Also, WOPs repressed gastric inflammation through the reduction of TNF-α, IL-6, IL-1β and increase IL-10 levels, and revealed antioxidant properties with the enhancement of superoxide dismutase, glutathione, and catalase activity, while reduction of malondialdehyde. Moreover, WOPs treatment significantly down-regulated Bax, caspase-3 and nuclear factor-κB p65 (NF-κB p65) expression, while up-regulating the expression of Bcl-2 and inhibitor kappa Bα (IκBα) protein. These results indicated that WOPs have protective effects against ethanol-induced gastric mucosal injury in rats through anti-inflammatory, anti-oxidation, and anti-apoptosis mechanisms.

Carbon Monoxide Being Hydrogen Sulfide and Nitric Oxide Molecular Sibling, as Endogenous and Exogenous Modulator of Oxidative Stress and Antioxidative Mechanisms in the Digestive System

Oxidative stress reflects an imbalance between oxidants and antioxidants in favor of the oxidants capable of evoking tissue damage. Like hydrogen sulfide (H₂S) and nitric oxide (NO), carbon monoxide (CO) is an endogenous gaseous mediator recently implicated in the physiology of the gastrointestinal (GI) tract. CO is produced in mammalian tissues as a byproduct of heme degradation catalyzed by the heme oxygenase (HO) enzymes. Among the three enzymatic isoforms, heme oxygenase-1 (HO-1) is induced under conditions of oxidative stress or tissue injury and plays a beneficial role in the mechanism of protection against inflammation, ischemia/reperfusion (I/R), and many other injuries. According to recently published data, increased endogenous CO production by inducible HO-1, its delivery by novel pharmacological CO-releasing agents, or even the direct inhalation of CO has been considered a promising alternative in future experimental and clinical therapies against various GI disorders. However, the exact mechanisms underlying behind these CO-mediated beneficial actions are not fully explained and experimental as well as clinical studies on the mechanism of CO-induced protection are awaited. For instance, in a variety of experimental models related to gastric mucosal damage, HO-1/CO pathway and CO-releasing agents seem to prevent gastric damage mainly by reduction of lipid peroxidation and/or increased level of enzymatic antioxidants, such as superoxide dismutase (SOD) or glutathione peroxidase (GPx). Many studies have also revealed that HO-1/CO can serve as a potential defensive pathway against oxidative stress observed in the liver and pancreas. Moreover, increased CO levels after treatment with CO donors have been reported to protect the gut against formation of acute GI lesions mainly by the regulation of reactive oxygen species (ROS) production and the antioxidative activity. In this review, we focused on the role of H₂S and NO molecular sibling, CO/HO pathway, and therapeutic potential of CO-releasing pharmacological tools in the regulation of oxidative stress-induced damage within the GI tract with a special emphasis on the esophagus, stomach, and intestines and also two solid and important metabolic abdominal organs, the liver and pancreas.

The role of hydrogen sulfide in gastrointestinal tract functioning (review)

Despite a fairly large amount of literature data about the involvement of hydrogen sulfide in physiological and pathophysiological processes, its role in gastrointestinal tract functioning has not been studied sufficiently. This review systematizes and generalizes the mechanisms of H2S-associated regulation of gastrointestinal secretion and motility on the basis of literature sources processing and own research results. We analysed world professional literature and sources in Google Scholar, PubMed, MedLine, Embase, Cochrane, and data from more than 50 articles and books on the problem were processed in the article. This review gives a synopsis of the H2S function in the regulation of the secretory and motor-evacuation function, and in stimulating the reparative properties of the digestive tract, and indicates the main mechanisms.

The Roles of NO and H2S in Sperm Biology: Recent Advances and New Perspectives

After being historically considered as noxious agents, nitric oxide (NO) and hydrogen sulfide (H2S) are now listed as gasotransmitters, gaseous molecules that play a key role in a variety of cellular functions. Both NO and H2S are endogenously produced, enzymatically or non-enzymatically, and interact with each other in a range of cells and tissues. In spite of the great advances achieved in recent decades in other biological systems, knowledge about H2S function and interactions with NO in sperm biology is in its infancy. Here, we aim to provide an update on the importance of these molecules in the physiology of the male gamete. Special emphasis is given to the most recent advances in the metabolism, mechanisms of action, and effects (both physiological and pathophysiological) of these gasotransmitters. This manuscript also illustrates the physiological implications of NO and H2S observed in other cell types, which might be important for sperm function. The relevance of these gasotransmitters to several signaling pathways within sperm cells highlights their potential use for the improvement and successful application of assisted reproductive technologies.

Synergisms, Discrepancies and Interactions between Hydrogen Sulfide and Carbon Monoxide in the Gastrointestinal and Digestive System Physiology, Pathophysiology and Pharmacology

Endogenous gas transmitters, hydrogen sulfide (H₂S), carbon monoxide (CO) and nitric oxide (NO) are important signaling molecules known to exert multiple biological functions. In recent years, the role of H₂S, CO and NO in regulation of cardiovascular, neuronal and digestive systems physiology and pathophysiology has been emphasized. Possible link between these gaseous mediators and multiple diseases as well as potential therapeutic applications has attracted great attention from biomedical scientists working in many fields of biomedicine. Thus, various pharmacological tools with ability to release CO or H₂S were developed and implemented in experimental animal in vivo and in vitro models of many disorders and preliminary human studies. This review was designed to review signaling functions, similarities, dissimilarities and a possible cross-talk between H₂S and CO produced endogenously or released from chemical donors, with special emphasis on gastrointestinal digestive system pathologies prevention and treatment.

Hydrogen Sulfide in Pharmacotherapy, Beyond the Hydrogen Sulfide-Donors

Hydrogen sulfide (H₂S) is one of the important biological mediators involved in physiological and pathological processes in mammals. Recently developed H₂S donors show promising effects against several pathological processes in preclinical and early clinical studies. For example, H₂S donors have been found to be effective in the prevention of gastrointestinal ulcers during anti-inflammatory treatment. Notably, there are well-established medicines used for the treatment of a variety of diseases, whose chemical structure contains sulfur moieties and may release H₂S. Hence, the therapeutic effect of these drugs may be partly the result of the release of H₂S occurring during drug metabolism and/or the effect of these drugs on the production of endogenous hydrogen sulfide. In this work, we review data regarding sulfur drugs commonly used in clinical practice that can support the hypothesis about H₂S-dependent pharmacotherapeutic effects of these drugs.

Oxidative gastric mucosal damage induced by ischemia/reperfusion and the mechanisms of its prevention by carbon monoxide-releasing tricarbonyldichlororuthenium (II) dimer

Endogenous gaseous mediators, such as nitric oxide, hydrogen sulfide or carbon monoxide (CO) are known to exert anti-inflammatory and anti-oxidative activity due to modulation of various molecular pahtways. Therefore, we aimed to investigate if CO released from tricarbonyldichlororuthenium (II) dimer (CORM-2) prevents gastric mucosa against ischemia/reperfusion (I/R)-induced injury in male Wistar rats. Animals were pretreated i.g. With vehicle (DMSO and saline, 1:10), CORM-2 (1, 5 or 10 mg/kg) or zinc protoporphyrin IX (ZnPP, 10 mg/kg i.p.), the HMOXs inhibitor. In separate series, rats were pretreated with CORM-2 (5 mg/kg) applied in combination with glibenclamide (10 mg/kg i.g.), N^G-nitro-l-arginine (L-NNA, 20 mg/kg i.p.), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 10 mg/kg i.p.) or indomethacin (5 mg/kg i.p.). I/R-injuries were induced by clamping celiac artery for 30 min (I) followed by removal of the clamp to obtain R for 3 h. The macroscopic and microscopic area of gastric damage, mucus production and protein expression for HMOX-1/Nrf-2 was determined by planimetry, histology and immunohistochemistry, respectively. Gastric mucosal HMOX-1, HMOX-2, COX-1, COX-2, Kir6.1, Sur2, sGC-α1, sGC-α2, iNOS and eNOS mRNA expression was assessed by real-time PCR. COHb in blood and gastric mucosal CO concentration was analyzed by gas chromatography. Serum content of TGF-β1, TGF-β2, TGF-β3, IL-1α, IL-1β, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12, TNF-α, IFN-γ, GM-CSF was evaluated using Luminex platform. PGE₂ concentration and 8-hydroxyguanozine (8-OHG) concentration in gastric mucosa was determined by ELISA. Exposure to I/R induced extensive hemorrhagic erosions in gastric mucosa pretreated with vehicle as compared with intact rats and the area of this gastric damage was reduced by pretreatment with CORM-2 (5 mg/kg i.g.). This effect of CO donor was accompanied by the increased PGE₂ content and a significant decrease in 8-OHG and expression of pro- and anti-inflammatory markers mRNA and proteins. Concurrent treatment of CORM-2 with glibenclamide, L-NNA, ODQ but not with indomethacin significantly increased the area of I/R-induced injury and significantly decreased GBF as compared with the group treated with CORM-2 alone. We conclude that CO releasing CORM-2 prevents gastric mucosal oxidative damage induced by I/R improving GBF, decreasing DNA oxidation and inflammatory response on systemic level. This CO-gastroprotection is mediated by the activity of sGC, NOS and K-ATP channels. CO delivered from its donor maintained physiological gastric mucosal PGE₂ concentration but the involvement of endogenous COX in beneficial activity of this gaseous mediator at least in this model is questionable.

Inhibition of hydrogen sulfide synthesis reverses acquired resistance to 5-FU through miR-215-5p-EREG/TYMS axis in colon cancer cells

Acquired resistance to 5-fluorouracil (5-FU) is a major barrier to benefit from chemotherapy in colon cancer patients. Hydrogen sulfide (H₂S), mainly produced by cystathionine-β-synthase (CBS), has been reported to promote the proliferation and migration of colon cancer cells. In this study, the effect of inhibiting H₂S synthesis on the sensitivity of colon cancer cell lines to 5-FU was investigated. Increased expression of CBS was validated in online database and tissue microarrays. Inhibiting H₂S synthesis significantly sensitized colon cancer cell lines to 5-FU both in vitro and in vivo. Decreasing H₂S synthesis utilizing shRNA lentiviruses significantly reversed the acquired resistance to 5-FU. MicroRNA sequencing was performed and miR-215-5p was revealed as one of the miRNAs with most significantly altered expression levels after CBS knock down. Epiregulin (EREG) and thymidylate synthetase (TYMS) were predicted to be potential targets of miR-215-5p. Decreasing H₂S synthesis significantly decreased the expression of EREG and TYMS. These results demonstrate that inhibiting H₂S synthesis can reverse the acquired resistance to 5-FU in colon cancer cells.

Decreased Expression of Cystathionine β-Synthase Exacerbates Intestinal Barrier Injury in Ulcerative Colitis

BACKGROUND AND AIMS

Endogenous H2S regulates multiple physiological and pathological processes in colon epithelial tissues. The current study investigated the role of cystathionine β-synthase [CBS], a major producer of H2S in colon epithelial cells, in the pathogenesis of ulcerative colitis [UC]-related intestinal barrier injury. The expression and DNA methylation level of CBS were investigated in inflamed and non-inflamed colon tissues collected from UC patients, and the effect of decreased CBS levels on Caco-2 monolayer barrier injury and altered status of tight junctions elicited by tumour necrosis factor/interferon [TNF/IFN] was determined.

METHODS

The expression of CBS and the methylation level of the CBS promoter were assessed in non-inflamed and inflamed colon epithelial tissue samples collected from UC patients. Barrier function, status of tight junction proteins and activation of the NF-κB p65-mediated MLCK-P-MLC signalling pathway were further investigated in Caco-2 monolayers.

RESULTS

Decreased expression of CBS and elevated methylation levels of the CBS promoter were observed in inflamed sites compared with in non-inflamed sites in the colon epithelial samples from UC patients. In Caco-2 monolayers, decreased expression of CBS exacerbated TNF/IFN-induced barrier injury and altered localization of tight junction proteins. Decreased expression of CBS predisposed Caco-2 monolayers to injury elicited by TNF/IFN via augmentation of the NF-κB p65-mediated MLCK-P-MLC signalling pathway.

CONCLUSIONS

Decreased expression of CBS propagates the pathogenesis of UC by exacerbating inflammation-induced intestinal barrier injury. Elevated methylation of the CBS promoter might be one of the mechanisms underlying the decreased expression of CBS in inflamed sites of colon epithelial tissues from UC patients.

Gastroduodenal Injury: Role of Protective Factors

PURPOSE OF REVIEW

The gastroduodenal mucosal layer is a complex and dynamic system that functions in an interdependent manner to resist injury. We review and summarize the most updated knowledge about gastroduodenal defense mechanisms and specifically address (a) the mucous barrier, (b) membrane and cellular properties, and vascular, hormonal, and (c) gaseous mediators.

RECENT FINDINGS

Trefoil factor family peptides play a crucial role in cellular restitution by increasing cellular permeability and expression of aquaporin channels, aiding cellular migration and tissue repair. Additionally, evidence suggests that the symptoms of functional dyspepsia may be attributed to alterations in the duodenum, including low-grade inflammation and increased mucosal permeability. The interaction of the various mucosal protective components helps maintain structural and functional homeostasis. There is increasing evidence suggesting that the upper GI microbiota plays a crucial role in the defense mechanisms. However, this warrants further investigation.

Time-dependent course of gastric ulcer healing and molecular markers profile modulated by increased gastric mucosal content of carbon monoxide released from its pharmacological donor

BACKGROUND AND PURPOSE

Besides hydrogen sulfide (H₂S) and nitric oxide (NO), carbon monoxide (CO) contributes to the maintenance of gastric mucosal integrity. We investigated increased CO bioavailability effects on time-dependent dynamics of gastric ulcer healing mediated by particular growth factors, anti-inflammatory and molecular pathways.

EXPERIMENTAL APPROACH

Wistar rats with gastric ulcers induced by serosal acetic acid application (day 0) were treated i.g. throughout 3, 6 or 14 days with vehicle or CO-releasing tricarbonyldichlororuthenium (II) dimer (CORM-2, 2.5 mg/kg). Gross and microscopic alterations in gastric ulcer size and gastric blood flow (GBF) at ulcer margin were determined by planimetry, histology and laser flowmetry, respectively. Gastric mRNA/protein expressions of platelet derived growth factors (PDGFA-D), insulin-like growth factor (IGF-1), epidermal growth factor (EGF), hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGFA) and their receptors, heme oxygenases (HMOX), nuclear factor (erythroid-derived 2)-like 2 (Nrf-2), cyclooxygenase (COX-2), hypoxia inducible factor (HIF)-1α, anti-inflammatory annexin-1 and transforming growth factor (TGF-β1) were assessed by real-time PCR or Western blot. TGF-β1-3 and IL-10 plasma concentration were measured using Luminex platform. Prostaglandin E₂ content at ulcer margin was assessed by ELISA.

KEY RESULTS

CORM-2 decreased ulcer area and increased GBF after 6 and 14 days of treatment comparing to vehicle. CO donor upregulated HGF, HGFr, VEGFR1, VEGFR2, TGF-β1, annexin-1 and maintained increased IGF-1, PDGFC and EGF expression at various time-intervals of ulcer healing. TGF-β3 and IL-10 plasma concentration were significantly increased after COMR-2 vs. vehicle.

CONCLUSIONS

CO time-dependently accelerates gastric ulcer healing and raises GBF at ulcer margin by mechanism involving subsequent upregulation of anti-inflammatory, growth promoting and angiogenic factors response, not observed physiologically.

Alterations in Gastric Mucosal Expression of Calcitonin Gene-Related Peptides, Vanilloid Receptors, and Heme Oxygenase-1 Mediate Gastroprotective Action of Carbon Monoxide against Ethanol-Induced Gastric Mucosal Lesions

Carbon monoxide (CO) has been reported to contribute to the maintenance of gastric mucosal integrity, gastroprotection, and ulcer healing. However, involvement of transient receptor potential vanilloid receptor type 1 (TRPV1) located on afferent sensory fibers endings and sensory neuropeptide calcitonin gene-related peptide (CGRP) in CO-mediated gastroprotection against ethanol-induced gastric damage has not been explored. Male Wistar rats with and without denervation of afferent sensory neurons induced by capsaicin (total dose 125 mg/kg within 3 days) were pretreated with vehicle, CO donor tricarbonyldichlororuthenium (II) dimer (CORM-2, 5 mg/kg i.g.), administered alone or with CGRP-α (10 μg/kg i.p.) or TRPV1 antagonist capsazepine (5 mg/kg i.g.), followed 30 min later by intragastric (i.g.) administration of 75% ethanol. The area of gastric damage and gastric blood flow (GBF) were assessed planimetrically and by laser flowmetry, respectively. Microscopic evaluation of ethanol-induced gastric lesions was performed after haematoxylin/eosin (H&E) or alcian blue/periodic acid-Schiff/alcian blue (AB/PAS) staining. Gastric mucosal mRNA fold change for heme oxygenase (HMOX)-1, HMOX-2, CGRP-α, CGRP-β, inducible nitric oxide synthase (iNOS), endothelial (e)NOS, neuronal (n)NOS, cyclooxygenase (COX)-1, COX-2, and protein expression for HMOX-1 and TRPV1 was determined by real-time PCR or Western blot, respectively. Pretreatment with CORM-2 combined or not with CGRP reduced ethanol-induced gastric lesions and elevated GBF. Capsaicin-denervation or co-treatment with capsazepine or CGRP and CORM-2 in capsaicin-denervated animals failed to affect these beneficial effects of CO donor. In rats with intact sensory nerves, CORM-2 increased gastric mRNA level for HMOX-1 and CGRP-α. In capsaicin-denervated rats, CORM-2 increased eNOS mRNA fold change and TRPV1 protein expression while capsaicin denervation itself decreased HMOX-1 protein expression and eNOS mRNA level. We conclude that CO prevents gastric mucosa from ethanol-induced lesions due to activation of TRPV1/CGRP-α system and accompanying increase in gastric microcirculation but independently on afferent sensory nerve activity despite the stimulation of TRPV1 protein and CGRP-α mRNA expression.

Nitric oxide and the biology of pregnancy

Nitric oxide (NO) is a key regulator of both maternal and fetal homeostasis during pregnancy, facilitating the maternal cardio-vascular changes, fetal development and growth and adaptation to extrauterine life. Dysfunction of the NO system during pregnancy is associated to placental and vascular-related diseases such as hypertensive disorders of pregnancy (HDP) and intrauterine growth restriction (IUGR). Emerging therapeutic strategies involving NO precursors, NO donors, natural derivatives or pharmacological modulators of the NO system seem hold promise for the treatment of such conditions of pregnancy.

Hydrogen Sulfide Reduces Myeloid-Derived Suppressor Cell-Mediated Inflammatory Response in a Model of Helicobacter hepaticus-Induced Colitis

Chronic inflammation contributes to tumor initiation in colitis-associated colorectal cancer (CRC). Indeed, inflammatory bowel disease (IBD) patients show an increased risk of developing CRC. Cancer immune evasion is a major issue in CRC and preclinical and clinical evidence has defined a critical role for myeloid-derived suppressor cells (MDSCs) that contribute to tumor growth and progression by suppressing T-cells and modulating innate immune responses. MDSCs comprise a heterogeneous population of immature myeloid cells that can be distinct in two subtypes: CD11b⁺Ly6G⁺Ly6C^low with granulocytic phenotype (G-MDSCs) and CD11b⁺Ly6G⁻Ly6C^high with monocytic phenotype (M-MDSCs). Hydrogen sulfide (H₂S) is an endogenous gaseous signaling molecule that regulates various physiological and pathophysiological functions. In particular, several studies support its anti-inflammatory activity in experimental colitis and ulcer. However, the role of the H₂S pathway in innate immune-mediated IBD has not yet been elucidated. To better define a possible link between MDSCs and H₂S pathway in colitis-associated CRC development, we used an innate immune-mediated IBD model induced by infection with the bacterium Helicobacter hepaticus (Hh), closely resembling human IBD. Here, we demonstrated an involvement of MDSCs in colitis development. A significant time-dependent increase of both G-MDSCs and M-MDSCs was observed in the colon and in the spleen of Hh-infected mice. Following, we observed that chronic oral administration of the H₂S donor DATS reduced colon inflammation by limiting the recruitment of G-MDSCs in the colon of Hh-infected mice. Thus, we identify the metabolic pathway l-cysteine/H₂S as a possible new player in the immunosuppressive mechanism responsible for the MDSCs-promoted colitis-associated cancer development.

Hydrogen Sulfide Releasing 2-Mercaptoacrylic Acid-Based Derivative Possesses Cytoprotective Activity in a Small Intestine of Rats with Medication-Induced Enteropathy

Small intestinal injury is known to be one of the most commonly appearing pathologies, resulting in the use of medications such as: nonsteroidal anti-inflammatory drugs (NSAIDs), antitumor drugs and angiotensin-converting enzyme (ACE) inhibitors. The principal objective of this study is to evaluate the action of a novel mercaptoacrylic acid derivative able to release H₂S on parameters of NO-synthase system and oxidative stress. Inducing enteropathy, three types of medications were used: indomethacin, an NSAID (35 mg/kg); methotrexate, an antitumor drug (10 mg/kg); and enalapril, an ACE inhibitor (2 mg/kg/day). 2-[(4-chlorophenyl-carbamoyl)-methyl]-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-acrylic acid (2C3DHTA) was introduced based on the background of medication-induced enteropathy (10 mg/kg/day). The survey showed that malondialdehyde (MDA) concentration, myeloperoxidase (MPO) activity, superoxide dismutase (SOD), catalase, and NO-synthases (NOS) were determined in the small intestinal mucosa. The increase in inducible NO-synthase (iNOS) activity was due to indomethacin and methotrexate administration. Constitutive NO-synthase (cNOS) activity was decreased by an ACE-inhibitor. The cytoprotective effect was demonstrated by 2C3DHTA, which returned iNOS activity to its control level and increased cNOS activity. The enterotoxic action of studied medication was accompanied by the development of oxidative stress manifested, activity of MPO was increased. MPO activity and manifestations of oxidative stress were decreased by 2C3DHTA. Effects of 2C3DHTA can be explained by the action of H₂S, released from this compound in the gastrointestinal (GI) system.