Pancreatic Diseases and Microbiota: A Literature Review and Future Perspectives

Intrapancreatic fat deposition and nutritional treatment: the role of various dietary approaches

Ectopic fat accumulation in various organs and tissues, such as the liver, muscle, kidney, heart, and pancreas, is related to impaired capacity of adipose tissue to accumulate triglycerides, as a consequence of overnutrition and an unhealthy lifestyle. Ectopic fat promotes organ dysfunction and is a key factor in the development and progression of cardiometabolic diseases. Interest in intrapancreatic fat deposition (IPFD) has developed in the last few years, particularly in relation to improvement in methodological techniques for detection of fat in the pancreas, and to growing evidence for the role that IPFD might have in glucose metabolism disorders and cardiometabolic disease. Body weight reduction represents the main option for reducing fat, and the evidence consistently shows that hypocaloric diets are effective in reducing IPFD. Changes in diet composition, independently of changes in energy intake, might offer a more feasible and safe alternative treatment to energy restriction. This current narrative review focused particularly on the possible beneficial role of the diet and its nutrient content, in hypocaloric and isocaloric conditions, in reducing IPFD in individuals with high cardiometabolic risk, highlighting the possible effects of differences in calorie quantity and calorie quality. This review also describes plausible mechanisms by which the various dietary approaches could modulate IPFD.

Microbiome and MicroRNA or Long Non-Coding RNA-Two Modern Approaches to Understanding Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of humans' most common and fatal neoplasms. Nowadays, a number of PDAC studies are being conducted in two different fields: non-coding RNA (especially microRNA and long non-coding RNA) and microbiota. It has been recently discovered that not only does miRNA affect particular bacteria in the gut microbiome that can promote carcinogenesis in the pancreas, but the microbiome also has a visible impact on the miRNA. This suggests that it is possible to use the combined impact of the microbiome and noncoding RNA to suppress the development of PDAC. Nevertheless, insufficient research has focused on bounding both approaches to the diagnosis, treatment, and prevention of pancreatic ductal adenocarcinoma. In this article, we summarize the recent literature on the molecular basis of carcinogenesis in the pancreas, the two-sided impact of particular types of non-coding RNA and the pancreatic cancer microbiome, and possible medical implications of the discovered phenomenon.

[Comparative analysis of the intestinal microbiota in patients with exocrine pancreatic insufficiency of various severity]

BACKGROUND

Exocrine pancreatic insufficiency (EPI) is a critical host factor in determining the composition of the gut microbiota. Diseases that cause exocrine insufficiency can affect the gut microbiome, which can potentiate disease progression and complications. To date, the relationship of exocrine insufficiency in various pancreatic (PA) pathologies, in chronic pancreatitis (CP), with dysbiotic changes in the intestinal microbiota (IM) has not been reliably studied. The available data are heterogeneous and contradictory, which determines the need for further research.

AIM

To conduct a comparative analysis of the taxonomic composition of the intestinal microbiota in patients with CP of various etiologies, without or with the presence of EPI of varying severity, as well as patients with severe EPI with a history of surgical intervention (SI) on the pancreas.

MATERIALS AND METHODS

A total of 85 patients were included in the study. Patients were divided into groups according to the severity of EPI: Group 1 (n=16) - patients with CP without EPI; Group 2 (n=11) - patients with CP and mild EPI; Group 3 (n=17) - patients with severe CP and EPI; Group 4 (n=41) - severe EPI in persons with a history of SI on the pancreas. Verification of CP was carried out according to clinical, anamnestic and instrumental data. The degree of EPI was determined by the level of pancreatic elastase-1 (PE-1) feces. Informed consent for the study was obtained for each patient, an anamnesis was collected, physical and laboratory examinations were performed, and a stool sample was obtained. DNA was extracted from each stool sample, the taxonomic composition of BM was determined by sequencing the bacterial 16S rRNA genes, followed by bioinformatic analysis.

RESULTS

We followed the changes in the gut microbiota from a group of patients with CP without EPI to a group with severe EPI, in those who underwent SI. At the level of the phylum, the IM of all groups showed the dominance of Firmicutes, with the lowest representation in the severe EPI group, both with SI and CP, and the growth of the Actinobacteria, Verrucomicrobiota and Fusobacteria types. The differential representation of childbirth varied: in patients with severe EPI and CP, compared with mild, statistically significant genera - Akkermansia, Ruminococcus gauvreauii group and Holdemanella; compared with CP without exocrine insufficiency, Prevotella, Ruminococcus gauvreauii group, Peptostreptococcus and Blautia dominated. The CP group with mild EPI was dominated by the following genera: Lachnospiraceae_ND 2004 group, Faecalitalea, Fusobacterium, Catenibacterium, Roseburia, Atopobium, Cloacibacillus, Clostridium innococum group, Ruminococcus torques group. All groups showed a low diversity of taxa with a predominance of opportunistic flora, including participants in oncogenesis.

CONCLUSION

The results of the study show that patients with CP of various etiologies and patients with severe EPI who underwent specific intervention on the pancreas have intestinal microbiota dysbiosis, the severity of which is significantly influenced by the degree of EPI.

Selective Decontamination of the Digestive Tract in Pancreatic Head Resections-A Propensity Score-Matched Analysis

(1) Background: The postoperative morbidity rate after pancreatic head resection remains high, partly due to infectious complications. The primary aim of this study was to analyze the influence of selective decontamination of the digestive tract (SDD) on the postoperative infection rate after pancreatic surgery. (2) Methods: From January 2019, the standard of care for patients undergoing pancreatic head resections at the Department for Visceral, Thoracic, and Vascular Surgery, University Hospital Dresden was the preoperative oral administration of SDD. The influence of SDD was evaluated for patients operated on between January 2019 and June 2020 in comparison to a propensity score-matched cohort, extracted from an existing database including all pancreatic resections from 2012 to 2018. The primary endpoint of the study was the shift of the bacterial load on the intraoperative bile swab test. The secondary endpoint was the association of SDD with postoperative complications. (3) Results: In total, 200 patients either with SDD (n = 100; 50%) or without SDD (non-SDD, n = 100; 50%) were analyzed. In the patient group without a preoperative biliary stent, 44% (n = 11) of the non-SDD group displayed positive bacterial results, whereas that was the case for only 21.7% (n = 10) in the SDD group (p = 0.05). Particularly, Enterobacter species (spp.) were reduced from 41.2% (n = 14) (non-SDD group) to 23.5% (n = 12) (SDD group) (p = 0.08), and Citrobacter spp. were reduced by 13.7% (p = 0.09) from the non-SDD to the SDD cohort. In patients with a preoperative biliary stent, the Gram-negative Enterobacter spp. were significantly reduced from 52.2% (n = 12) in the non-SDD group to 26.8% (n = 11) in the SDD group (p = 0.04). Similarly, Citrobacter spp. decreased by 20.6% from 30.4% (n = 7) to 9.8% (n = 4) in the non-SDD compared to the SDD group (p = 0.04). In general, deep fluid collection and abscesses occurred more frequently in the non-SDD group (36%; n = 36 vs. 27%; n = 27; p = 0.17). (4) Conclusions: Adoption of SDD before pancreatic head surgery may reduce the bacterial load in bile fluid. SDD administration does not significantly affect the postoperative infectious complication rate after pancreatic head resections.

Responses of Ileal and Fecal Microbiota to Withdrawal of Pancreatic Enzyme Replacement Therapy in a Porcine Model of Exocrine Pancreatic Insufficiency

Little is known regarding the interplay between microbiota and pancreas functions in humans as investigations are usually limited to distal sites, namely the analyses of fecal samples. The aim of this study was to investigate both ileal and fecal microbiota in response to pancreatic enzyme replacement therapy (PERT) in a porcine model of exocrine pancreatic insufficiency (EPI). PERT was stopped for ten days in ileo-cecal fistulated minipigs with experimentally induced EPI (n = 8) and ileal digesta as well as fecal samples were obtained before withdrawal, during withdrawal and after the reintroduction of PERT. Profound community changes occurred three days after enzyme omission and were maintained throughout the withdrawal phase. A reduction in α-diversity together with relative abundance changes in several taxa, in particular increases in Bifidobacteria (at both sites) and Lactobacilli (only feces) were observed. Overall, dysbiosis events from the ileum had accumulating effects in distal parts of the gastrointestinal tract with additional alterations occurring only in the colon. Changes were reversible after continuing PERT, and one week later, bacterial communities resembled those at baseline. Our study demonstrates the rapid and profound impacts of enzyme withdrawal in bacterial communities, contributing to our understanding of the interplay between pancreas function and microbiota.

Current and New Challenges in the Management of Pancreatic Neuroendocrine Tumors: The Role of miRNA-Based Approaches as New Reliable Biomarkers

Pancreatic neuroendocrine tumors (PanNETs) are rare tumors; however, their incidence greatly increases with age, and they occur more frequently among the elderly. They represent 5% of all pancreatic tumors, and despite the fact that low-grade tumors often have an indolent evolution, they portend a poor prognosis in an advanced stages and undifferentiated tumors. Additionally, functional pancreatic neuroendocrine tumors greatly impact quality of life due to the various clinical syndromes that result from abnormal hormonal secretion. With limited therapeutic and diagnostic options, patient stratification and selection of optimal therapeutic strategies should be the main focus. Modest improvements in the management of pancreatic neuroendocrine tumors have been achieved in the last years. Therefore, it is imperative to find new biomarkers and therapeutic strategies to improve patient survival and quality of life, limiting the disease burden. MicroRNAs (miRNAs) are small endogenous molecules that modulate the expression of thousands of genes and control numerous critical processes involved in tumor development and progression. New data also suggest the implication of miRNAs in treatment resistance and their potential as prognostic or diagnostic biomarkers and therapeutic targets. In this review, we discusses the current and new challenges in the management of PanNETs, including genetic and epigenetic approaches. Furthermore, we summarize the available data on miRNAs as potential prognostic, predictive, or diagnostic biomarkers and discuss their function as future therapeutic targets.