Interleukin-17A Promotes Esophageal Adenocarcinoma Progression Through ROS/NF-kappa B/MMP-2/9 Signaling Pathway Activation

Background and aim: Hydrogen sulfide (H 2 S), nitric oxide (NO) and carbon monooxide are major physiological gasotransmitters that regulate various function of gastrointestinal tract.It is well established that NO plays a crucial role in lower esophageal sphincter (LES) function; however, it remains to be determined if H 2 S plays any roles in LES function.Here we investigate any contribution of endogenous H 2 S to LES function and its underlying mechanisms.Method: The circular smooth muscle strips of LES were prepared from porcine esophagus obtained at a local slaughterhouse, and their isometric contraction was monitored.In some experiments, the changes in intracellular Ca 2+ concentration ([Ca 2+ ] i ) and force were simultaneously monitored in the fura-2-loaded strips by using front-surface fluorometry.The contribution of endogenous H 2 S to LES function was investigated by inhibiting major H 2 S-generating enzymes: cystathionine-b-synthase (CBS), cystathionine-g-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3MST).Key Results: Myogenic regulation of smooth muscle tone plays an essential role in LES function.In porcine LES strips, the tone at rest was maintained at level of 4.97±0.150mN (n=5).This basal tone was not affected by 1 mM tetrodotoxin, thus suggesting the myogenic regulation of the basal tone.The application of either aminooxyacetic acid (AOA; CBS inhibitor) or aspartate (Asp; 3MST inhibitor), but not DL-propargylglycine (CSE inhibitor), decreased the basal tone of LES strips.Combination of AOA and Asp additively reduced the basal tone, while the maximal reduction (-3.51±0.143mN, n=5) was obtained at 1 mM AOA plus 3 mM Asp.In line with this, immunohistochemical analysis revealed the expression of CBS and 3MST, but not CBE in smooth muscle of LES.The reduction of basal tone by AOA plus Asp was accompanied by decrease in [Ca 2+ ] i .The extents of decreases in basal tone by AOA plus Asp were inversely correlated with the concentration of extracellular Na + (Na o ) (138mM-25mM).When Na o decreased to 25 mM, the reduction of basal tone by AOA plus Asp decreased to 12.4±2.67%(n=4) of that seen with 138 mM Na o .Conclusion: We demonstrate for the first time that endogenously generated H 2 S play a role in maintaining myogenic tone in LES, probably by either inhibiting forward mode or activating reverse mode of Na + /Ca 2+ exchanger, and thereby maintaining basal level of [Ca 2+] i .Targeting the myogenic regulation of LES by endogenous H 2 S could be potentially useful as a new therapeutic strategy for the treatment of esophageal motility disorders such as achalasia.