Gut microbiota-derived nicotinamide mononucleotide alleviates acute pancreatitis by activating pancreatic SIRT3 signalling.

BACKGROUND AND PURPOSE: Gut microbiota dysbiosis induced by acute pancreatitis (AP) exacerbates pancreatic injury and systemic inflammatory responses. The alleviation of gut microbiota dysbiosis through faecal microbiota transplantation (FMT) is considered a potential strategy to reduce tissue damage and inflammation in many clinical disorders. Here, we aim to investigate the effect of gut microbiota and microbiota-derived metabolites on AP and further clarify the mechanisms associated with pancreatic damage and inflammation. EXPERIMENTAL APPROACH: AP rat and mouse models were established by administration of caerulein or sodium taurocholate in vivo. Pancreatic acinar cells were exposed to caerulein and lipopolysaccharide in vitro to simulate AP. KEY RESULTS: Normobiotic FMT alleviated AP-induced gut microbiota dysbiosis and ameliorated the severity of AP, including mitochondrial dysfunction, oxidative damage and inflammation. Normobiotic FMT induced higher levels of NAD+ (nicotinamide adenine dinucleotide)-associated metabolites, particularly nicotinamide mononucleotide (NMN). NMN administration mitigated AP-mediated mitochondrial dysfunction, oxidative damage and inflammation by increasing pancreatic NAD+ levels. Similarly, overexpression of the NAD+ -dependent mitochondrial deacetylase sirtuin 3 (SIRT3) alleviated the severity of AP. Furthermore, SIRT3 deacetylated peroxiredoxin 5 (PRDX5) and enhanced PRDX5 protein expression, thereby promoting its antioxidant and anti-inflammatory activities in AP. Importantly, normobiotic FMT-mediated NMN metabolism induced SIRT3-PRDX5 pathway activation during AP. CONCLUSION AND IMPLICATIONS: Gut microbiota-derived NMN alleviates the severity of AP by activating the SIRT3-PRDX5 pathway. Normobiotic FMT could be served as a potential strategy for AP treatment.

HYAL-1-induced autophagy facilitates pancreatic fistula for patients who underwent pancreaticoduodenectomy.

The main mechanism of hyaluronidase 1(HYAL-1) in the development of postoperative pancreatic fistula (POPF) after pancreatoduodenectomy (PD) was unknown. In this study, a comprehensive inventory of pre-, intra-, and postoperative clinical and biological data of two cohorts (62 pancreatic cancer [PCa] and 111 pancreatic ductal adenocarcinoma [PDAC]) which could induce POPF were retrospectively analyzed. Then, a total of 7644 genes correlated with HYAL-1 was predicted in PDAC tissues and the enriched pathway, kinase targets and biological process of those correlated genes were evaluated. Finally, a mouse pancreatic fistula (PF) model was first built and in vitro studies were performed to investigate the effects of HYAL-1 on PF progression. Our data indicated that preoperative serum HYAL-1 level, pancreatic fibrosis score, and pancreatic duct size were valuable factors for detecting POPF of Grade B and C. The serum HYAL-1 level of 2.07 mg/ml and pancreatic fibrosis score of 2.5 were proposed as the cutoff values for indicating POPF. The bioinformatic analysis and in vitro and in vivo studies demonstrated that HYAL-1 facilitates pancreatic acinar cell autophagy via the dephosphorylation of adenosine 5'-monophosphate-activated protein kinase (AMPK) and signal transducers and activators of transcription 3 (STAT3) signaling pathways, which exacerbate pancreatic secretion and inflammation. In summary, the preoperative serum HYAL-1 was a significant predictor for POPF in patients who underwent PD. Tumor-induced HYAL-1 is one of core risk in accelerating PF and then promoting pancreatic secretion and acute inflammation response through the AMPK and STAT3-induced autophagy.

Plasma and tumor levels of Linc-pint are diagnostic and prognostic biomarkers for pancreatic cancer.

Long intergenic non-protein coding RNA, p53 induced transcript (Linc-pint) is a long noncoding RNA (lncRNA) that regulates tumor cell viability and proliferation. We used qRT-PCR and RNA FISH analysis to evaluate Linc-pint levels in the plasma and tumor tissues of pancreatic cancer (PCa) patients. Our data demonstrate that Linc-pint expression is lower in plasma samples from PCa patients than from healthy individuals, and indicate that plasma Linc-pint levels are more sensitive than CA19-9 for detecting PCa. Our data also show that Linc-pint levels are lower in PCa tumors than in adjacent tissues, carcinoma of the ampulla of Vater (CAV) and cholangiocarcinoma (CCA), and suggest that Linc-pint could be used for distinguishing the cause of malignant obstructive jaundice. Low plasma Linc-pint levels correlate with tumor recurrence, while low tumor Linc-pint levels correlate with poor prognosis for PCa patients after pancreatectomy. These results thus indicate that low plasma Linc-pint expression could serve as a minimally invasive biomarker for early PCa detection, and that low Linc-pint levels in PCa tumors could be used for predicting patient prognosis.