Introduction
Chronic pancreatitis is one of the well-known risk factors of pancreatic adenocarcinoma, the 4th leading cause of cancer mortality. Excessive chronic alcohol consumption is the first cause leading to chronic pancreatic and hepatic inflammation. The intestinal microbiota plays a role in the pathogenesis of these two diseases and patients with chronic alcoholic pancreatitis (CAP) or alcoholic hepatitis (AH) display altered and specific gut dysbiosis, with a higher relative abundance of Enterococcus in patients with CAP compared to AH(1). A recent study identified strains of E. faecalis able to produce a toxin, called cytolysin, responsible for liver lesions in chronic liver diseases. Its presence was associated with the worst clinical outcomes(2). It is yet unknown whether patients with CAP also exhibit an elevated relative abundance of cytolysin-producing E. faecalis strains.
Aims & Methods
The objectives of this study were 1/ to assess the presence of E. faecalis strains expressing or not cytolysin, in the intestinal microbiota of patients with CAP (n = 24) compared to patients with AH (n = 27) and to healthy controls (HC, n = 28), 2/ to evaluate the role of E. faecalis strains (isolated from the patients), in the genesis and potentiation of pancreatitis lesions and early precancerous lesions (acinar-to-ductal metaplasia), in a murine model of pancreatitis induced by cerulein, and 3/ to assess the presence of Enterococcus in surgical specimens of patients who went under pancreatic resection for CAP, (n = 6) compared to controls (normal pancreatic parenchyma apart of benign tumors n = 4).
Results
Our data showed that the relative abundance of cytolysin-positive E. faecalis in the intestinal microbiota is elevated in patients with AH and even more in patients with CAP. Genomic DNA of E. faecalis was detected in 96% of CAP patients, and 85% of AH patients. CAP patients were more frequently cytolysin-positive (96%) than HC (39%, p < 0.001) or AH patients (48%, p < 0.001). The relative abundance of cytolysin-positive E. faecalis was elevated in CAP and AH patients (p = 0.0006 and p= 0.0067) but not HC. In our murine model of cerulein-induced chronic pancreatitis, E. faecalis tend to increase the rate of pancreatitis lesions, as well as the number of acinar-to-ductal metaplasia lesions, specifically when pancreatitis is triggered. We used two different anti-Enterococcus antibodies with concordant results, showing that Enterococcus is present in the pancreatic parenchyma of patients with CAP, but not in the healthy pancreas of controls.
Conclusion
These results support a potentially detrimental role of Enterococcus, and especially E. faecalis, in the evolution of pancreatic inflammation. This study opens new research perspectives to investigate the pathophysiological mechanisms of intestinal microbiota species in the pancreatic exocrine tissue. Microbiota and metabolites produced by these microorganisms (like cytolysin) are probably key actors in the pancreatic inflammation process, involved in the cross-talk between the gut and pancreas. It could lead to consider potential new therapeutic targets in patients with chronic pancreatitis at risk of developing aggressive pancreatic cancers.
References
1. Ciocan D, Rebours V, Voican CS, Wrzosek L, Puchois V, Cassard AM, et al. Characterization of intestinal microbiota in alcoholic patients with and without alcoholic hepatitis or chronic alcoholic pancreatitis. Sci Rep. 19 mars 2018;8(1):4822.
2. Duan Y, Llorente C, Lang S, Brandl K, Chu H, Jiang L, et al. Bacteriophage targeting of gut bacterium attenuates alcoholic liver disease. Nature. nov 2019;575(7783):505‑11.