Exogenous H2S promotes ion channel reconstruction to regulate colonic motility in rats with dinitrobenzene sulfonic acid-induced colitis.

Background: Hydrogen sulfide (H2S) is a newly recognized endogenously generated gasotransmitter. Endogenous H2S has been shown to be related to several gastrointestinal diseases, including irritable bowel syndrome, Crohn's disease, and ulcerative colitis. We explored the functional role of H2S in colitis and investigated the underlying mechanism. Methods: Rats were randomly divided into control, model, and sodium hydrosulfide (NaHS) groups. Rat colitis was evaluated using the disease activity index and hematoxylin and eosin (HE) staining. The collected rat feces and intestinal charcoal transit were examined to determine intestinal motility. Enzyme-linked immunoassay kits were used to determine inflammatory factors in the rat blood. Calcium ion distribution and the protein expression of Potassium voltage gated channel subfamily D member 3 (KCND3), Maxi Potassium channel alpha (KCNMA1) and potassium inwardly rectifying channel J8 (KCNJ8) in rat smooth muscle were determined using an intracellular calcium detection kit, quantitative-reverse transcription polymerase chain reaction (qRT-PCR) and Western blot, respectively. Results: The results showed that H2S donor NaHS improved the intestinal mucosa of colitis rats by alleviating the tissue edema and congestion and repairing the gland structure of the intestinal mucosa. NaHS also reduced the levels of inflammatory factors containing interleukin (IL)-1ß, tumor necrosis factor alpha, and IL-6 in the rat blood. Additionally, the NaHS intervention partially restored rat intestinal motility by downregulating the proteins and mRNA expression of KCND3, KCNMA1, and KCNJ8 to reconstruct the ion channels. Conclusions: Our findings provide novel insights into the effect of H2S regulation on the anti-inflammatory action.

Exogenous H2S Protects Colon Cells in Ulcerative Colitis by Inhibiting NLRP3 and Activating Autophagy.

Hydrogen sulfide (H2S) has been reported to participate in intestinal mucosal defense and repair. However, the precise regulatory mechanisms of H2S in ulcerative colitis (UC) remain unclear. We explored the effects of sodium hydrosulfide (NaHS), a donor of H2S, in dextran sulfate sodium (DSS)-induced colitis in rats. The pathologic features were determined by analyzing the hematoxylin and eosin-stained samples. Interleukin-1ß (IL-1ß), IL-6, tumor necrosis factor-α (TNF-α), and myeloperoxidase (MPO) levels were determined using ELISA. The presence of cystathionine-γ-lyase (CSE) and light chain 3B (LC3B) were determined using immunohistochemical and immunofluorescence (IF) approaches, respectively. Next, we investigated the effects of NaHS in lipopolysaccharide (LPS)-stimulated human colonic smooth muscle cells (H2940). The level of reactive oxygen species (ROS) was determined using IF. NOD-like receptor 3 (NLRP3) and CSE were detected using western blot and quantitative real-time polymerase chain reaction. Autophagy was determined using western blot, IF, and electron microscopy. NaHS treatment considerably diminished colitis-induced histological injury and proinflammatory cytokine expressions. MPO, CSE, and H2S were downregulated, whereas LC3B was upregulated after NaHS administration in colitic rats. NaHS remarkably attenuated the levels of ROS, CSE, and NLRP3 in LPS-stimulated cells and enhanced autophagy, as was revealed by increased LC3-II-to-LC3-I ratio, elevated LC3, and decreased p62. Importantly, NaHS promoted autophagosome formation in LPS-treated cells. Exogenous H2S ameliorates intestinal injury by downregulating inflammation and activation of autophagy, suggesting the potential of NaHS as a therapeutic agent for UC.

Release of endogenous hydrogen sulfide in enteric nerve cells suppresses intestinal motility during severe acute pancreatitis.

Previous studies have shown that during severe acute pancreatitis (SAP) attacks, hydrogen sulfide (H2S) is released in the colon. However, the roles played by H2S in regulating enteric nerves remain unclear. In this study, we examined the association between SAP-induced H2S release and loss of intestinal motility, and also explored the relevant mechanism in enteric nerve cells. A rat SAP model was constructed and enteric nerve cells were prepared. Intestinal mobility was evaluated by measuring the number of bowel movements at indicated time points and by performing intestinal propulsion tests. The production of inflammatory cytokines during a SAP attack was quantified by ELISA, and the levels of cystathionine-γ-lyase (CSE) and cystathionine-ß-synthase (CBS) were examined by immunohistochemistry and western blot analysis. In vivo studies showed that PI3K/Akt/Sp1 signaling in enteric nerve cells was blocked, confirming the mechanism of endogenous H2S formation by western blot analysis and immunofluorescence. Our results also showed that rats with SAP symptoms had reduced intestinal motility. Furthermore, PI3K/Akt/Sp1 signaling was triggered and CSE expression was up-regulated, and these changes were associated with H2S formation in the colon. In addition, propargylglycine reduced the levels of inflammatory cytokines and suppressed the release of H2S. Enteric nerve cells that were incubated with LY294002 and transfected with a Sp1-knockdown vector displayed decreased levels of CSE production, which led to a decrease in H2S production. These results suggest that SAP symptoms suppressed the intestinal motility of rats via the release of H2S in enteric nerve cells, which was dependent on the inflammation-induced PI3K/Akt/Sp1 signaling pathway.

Curcumin regulates the miR-21/PTEN/Akt pathway and acts in synergy with PD98059 to induce apoptosis of human gastric cancer MGC-803 cells.

OBJECTIVE: PD98059 is a potent and selective inhibitor of mitogen-activated protein kinase. Substantial preclinical evidence has shown an anti-tumor effect of curcumin on various solid tumors. This study aimed to investigate whether curcumin synergistically acts with PD98059 in exerting anti-gastric cancer effects. METHODS: The cell counting kit-8 assay was used to detect cell proliferation of the human gastric cancer MGC-803 cell line. Flow cytometry was performed to detect apoptosis. Western blotting was used to detect phosphatase and tensin homolog (PTEN) and phosphorylated Akt (p-Akt) expression levels. Quantitative reverse transcription-polymerase chain reaction was used to determine microRNA-21 (miR-21). RESULTS: A dose of 5 to 40 µM curcumin inhibited proliferation of MGC-803 cells in a dose- and time-dependent manner. A high dose of curcumin strongly inhibited p-Akt protein expression. With increasing curcumin levels, PTEN expression increased and miR-21 levels decreased. These results suggest that curcumin negatively modulated the miR-21/PTEN/Akt pathway. Moreover, after pretreatment with PD98059, cell apoptosis induced by curcumin was significantly increased. Additionally, the inhibitory effects of curcumin on the miR-21/PTEN/Akt pathway were significantly enhanced. CONCLUSION: PD98059 combined with curcumin may be a potential strategy for managing gastric cancer.

Pro-inflammatory cytokine-driven PI3K/Akt/Sp1 signalling and H2S production facilitates the pathogenesis of severe acute pancreatitis.

Severe acute pancreatitis (SAP) is a disease usually associated with systemic organ dysfunction or pancreatic necrosis. Most patients with SAP suffer from defective intestinal motility in the early phase of the disease. Additionally, SAP-induced inflammation produces hydrogen sulphide (H2S) that impairs the gastrointestinal (GI) system. However, the exact mechanism of H2S in the regulation of SAP is yet to be elucidated. In the present paper, we used a rat model of SAP to evaluate the role of H2S on intestinal motility by counting the number of bowel movements and investigating the effect of H2S on inflammation. We treated colonic muscle cells (CMCs) with SAP plasma, tumour necrosis factor-α (TNF-α) or interleukin-6 (IL-6) and measured the expressions of H2S-producing enzymes cystathionine-γ-lyase (CSE), cystathionine-ß-synthase (CBS) and Sp1 and PI3K/Akt by using quantitative PCR, Western blotting and immunohistochemical detection. We used the PI3K inhibitor LY294002 and the siRNA si-Sp1 to suppress the activity of the PI3K/Akt/Sp1 signalling pathway. We found that, in the SAP rat model, H2S facilitated an inhibitory effect on intestinal motility and enhanced the inflammatory response caused by SAP (P<0.05). The expressions of CSE and CBS in CMCs were significantly increased after treatment with TNF-α or IL-6 (P<0.05). Blocking the PI3K/Akt/Sp1 pathway remarkably inhibited the synthesis of CSE and CBS. Our data demonstrated that H2S plays a vital role in the pathogenesis of SAP and that SAP is modulated by inflammation driven by the PI3K/Akt/Sp1 signalling pathway.