Hydrogen sulphide exacerbates acute pancreatitis by over-activating autophagy via AMPK/mTOR pathway.

Liang Ji,Yongwei Wang,Shangha Pan,Le Li,Xuewei Bai,Gang Wang,Dongbo Xue,Bei Sun,Guangquan Zhang,Fengzhi Qu

doi:10.1111/jcmm.12928

Abstract

Previously, we have shown that hydrogen sulphide (H2S) might be pro‐inflammatory during acute pancreatitis (AP) through inhibiting apoptosis and subsequently favouring a predominance of necrosis over apoptosis. In this study, we sought to investigate the detrimental effects of H2S during AP specifically with regard to its regulation on the impaired autophagy. The incubated levels of H2S were artificially intervened by an administration of sodium hydrosulphide (NaHS) or DL‐propargylglycine (PAG) after AP induction. Accumulation of autophagic vacuoles and pre‐mature activation of trypsinogen within acini, which indicate the impairment of autophagy during AP, were both exacerbated by treatment with NaHS but attenuated by treatment with PAG. The regulation that H2S exerted on the impaired autophagy during AP was further attributed to over‐activation of autophagy rather than hampered autophagosome–lysosome fusion. To elucidate the molecular mechanism that underlies H2S‐mediated over‐activation of autophagy during AP, we evaluated phosphorylations of AMP‐activated protein kinase (AMPK), AKT and mammalian target of rapamycin (mTOR). Furthermore, Compound C (CC) was introduced to determine the involvement of mTOR signalling by evaluating phosphorylations of downstream effecters including p70 S6 kinase (P70S6k) and UNC‐51‐Like kinase 1 (ULK1). Our findings suggested that H2S exacerbated taurocholate‐induced AP by over‐activating autophagy via activation of AMPK and subsequently, inhibition of mTOR. Thus, an active suppression of H2S to restore over‐activated autophagy might be a promising therapeutic approach against AP‐related injuries.

Highlights

Acute pancreatitis (AP) is an abdominal emergency with considerable morbidity and mortality because of its concomitant organ failures and other eventful complications [1]
The exact mechanisms involved in the pathogenesis of AP have not been well elucidated, accumulation of cytoplasmic vacuoles and pre-mature activation of trypsinogen within acini were long noticed as the two early-phase features of AP
The administration of NaHS significantly potentiated the percentage of autophagic vacuoles per cytoplasm area, whereas the administration of PAG significantly weakened the percentage of autophagic vacuoles per cytoplasm area, compared with that in AP group (Fig. 2A)

Summary

Introduction

Acute pancreatitis (AP) is an abdominal emergency with considerable morbidity and mortality because of its concomitant organ failures and other eventful complications [1]. Hydrogen sulphide synthesizing activity in pancreatic homogenates was measured as previously described [14, 22]. The sections were observed under a light microscope and the expression of protein was quantified by integrated optical density (IOD) with Image-Pro Plus v6.0 software (Media Cybernetics, Crofton, MA, USA) in 20 randomly selected fields. Induction, compared with that in AP group (Fig. 1B) Such statistically significant deviations that correlated with the interventions against the incubated level of H2S could not be satisfactorily identified at 3 or 12 hrs (Fig. S1C and D). To confirm the increase in the level of H2S after AP induction and the validation of our interventions, the serum levels of H2S and H2S synthesizing activities in pancreatic homogenates were calculated against a calibration curve of NaHS and expressed as NaHS equivalent. A P-value of

Results

Discussion

Conflict of interest