Acute pancreatitis represents one of the most common gastrointestinal conditions, increasingly occurring disease and being a frequent cause of hospitalization18. Currently, alcohol abuse represents the most common etiological contributor to acute pancreatitis in humans worldwide3,8. Although substantial progress has been made in understanding the processes of alcoholic pancreatitis, the particular mechanisms remain unknown8,19. Inflammatory cytokines are involved in the inflammatory response of alcoholic pancreatitis and could be either pro- or anti- inflammatory cytokines depending on their roles8,19. Our previous study showed that chronic alcohol feeding can lead to epigenetic changes in the IL-1α and IL-10 genes and tissue injury in the pancreas of rats, with cooked rhubarb acting as a protective factor10. The purpose of this study was to determine whether cooked rhubarb may help rats with alcohol-induced acute pancreatitis by modulating the epigenetics of inflammatory cytokine genes and histopathology.
Although alcohol abuse or alcoholism are one of the major causes of pancreatic disease, the incidence of clinical pancreatitis in heavy drinkers is low 8,20. These results indicated that other
factors (such as genetic background) might be involved in the pathogenesis of acute pancreatitis8. Epigenetic modifications, including DNA methylation and histone modifications, affect gene expression without altering the DNA code6,7. Chronic alcohol use causes epigenetic alterations in inflammatory genes in rat pancreatic tissue, according to our prior study10. First, the experiments in the study were designed to assess the influence of acute pancreatitis and/or chronic alcohol exposure on the epigenetics of inflammatory genes and pathological damage in the pancreas of rats by a 2×2 factorial design. Our results suggested that alcohol exposure stimulation statistically suppressed the IL-1α methylated DNA levels and increased the IL-10 methylated DNA levels. However, a subsequent study found that acinar cells exposed to alcohol produced significantly more IL-1α, while less IL-10 was produced. Meanwhile, our findings showed that after acute pancreatitis stimulation, DNA methylation of IL-10 was reduced and IL-10 protein production was enhanced, but IL-1α did not change. Furthermore, in acute pancreatitis stimulation and alcohol exposure, a link was discovered between changes in the DNA methylation of IL-10 and the protein expression of IL-1α and IL-10 in interstitial cells. Finally, acute pancreatitis stimulation significantly increased pathological pancreatic injury, but alcohol exposure did not show a similar effect. The findings show that while alcohol exposure alone can modify the epigenetics of inflammatory markers (IL-1α and IL-10), it is insufficient to produce severe pathological damage in the rat pancreas. Other researchers have also observed similar findings. Setiawan VW et al reported that alcohol administration alone dose not initiate pancreatitis but dose sensitize the pancreas to pancreatitis by other insults21. As described in these epidemiologic studies20, pancreatitis appears to be triggered by repeated acute attacks in combination with alcohol binge drinking and other factors, such as epigenetics. The above results indicate that acute pancreatitis stimulation combined with alcohol exposure, at least in part, modified the DNA methylation of IL-1α and IL-10, related protein expression, and pathological damage in the rat pancreas.
While abstinence from alcohol is the most essential first suggestion for these individuals with alcoholic pancreatitis to decrease disease recurrence and progression, no particular therapy is available at this time3,8. Rhubarb, an ancient Chinese medicine, has been used as an anti-
inflammatory drug for a long time22. Rhubarb has been shown to reduce inflammatory reactions and attenuate organ injury in acute pancreatitis in previous studies12,13. Therefore,in a second phase of our experiments, we used a 2×2 factorial design to investigate the effects of acute pancreatitis and/or cooked rhubarb therapy on DNA methylation and protein expression of IL-1α and IL-10, and the severity of pathological damage in pancreatic tissues of rats fed with alcohol. We found that cooked rhubarb therapy significantly increased the methylation level of IL-1α DNA while inhibiting the methylation level of IL-10 DNA in the alcohol-exposed pancreas. Meanwhile, cooked rhubarb treatment increased the IL-10 protein expression in the interstitial tissue and acinar tissues but decreased the IL-1α protein in the acinar tissues. The pathological injury of the pancreas was significantly increased by acute pancreatitis stimulation, whereas the pathological injury of the pancreas was clearly alleviated by cooked rhubarb therapy. In addition, there was an interaction between acute pancreatitis stimulation and alcohol exposure on the alteration of the DNA methylation levels of IL-1α and IL-10, related protein expression, and pathological damage in the pancreas of alcohol-exposed rats, according to subgroup analysis. The above-mentioned findings suggest that cooked rhubarb treatment decreased DNA methylation, protein expression of inflammatory genes and pathological damage in rats with alcoholic pancreatitis.
Pancreatic acini and interstitial (stellate and duct) cells make up the exocrine pancreas. Pancreatic acinar cells manufacture and release digestive enzymes, the pancreatic duct transports digestive enzymes to the duodenum, and pancreatic stellate cells are myofibroblast-like cells linked with the pancreatic fibrosis of chronic pancreatitis19,23. Pancreatic acinar cells, as well as interstitial cells, play a role in the general pathophysiology of pancreatitis18,19. Chronic alcohol misuse is linked to pancreatic acinar cell destruction in acute pancreatitis, as well as pancreatic interstitial fibrosis in chronic inflammation, according to recent research8,19. Alcohol causes pancreatic stellate cells to boost IL-8 production and connective tissue development, according to previous reports by Masamune et al24. Our findings also support this theory. Our findings showed that chronic alcohol exposure combined with acute pancreatitis,at least in part, affects IL-1α and IL-10 protein expression not only in pancreatic acini but also in interstitial cells. In the pancreatic acini and interstitial cells of rats, cooked rhubarb administration successfully reduced alterations in the expression levels of IL-1α and IL-10 protein caused by acute pancreatitis stimulation and/or alcohol exposure. Alcohol and its metabolites have previously been found to activate the MAPK, ERK1/2, JNK, and p38K pathways in pancreatic interstitial cells8,25–27. Because of their influence on cytokine production, all of these signals are related to inflammation in alcoholic pancreatitis27.