Gut microbiota in pancreatic diseases: possible new therapeutic strategies

Heterogeneous changes in gut and tumor microbiota in patients with pancreatic cancer: insights from clinical evidence

BACKGROUND

Pancreatic cancer is the foremost contributor to cancer-related deaths globally, and its prevalence continues to rise annually. Nevertheless, the underlying mechanisms behind its development remain unclear and necessitate comprehensive investigation.

METHODS

In this study, a total of 29 fresh stool samples were collected from patients diagnosed with pancreatic cancer. The gut microbial data of healthy controls were obtained from the SRA database (SRA data number: SRP150089). Additionally, 28 serum samples and diseased tissues were collected from 14 patients with confirmed pancreatic cancer and 14 patients with chronic pancreatitis. Informed consent was obtained from both groups of patients. Microbial sequencing was performed using 16s rRNA.

RESULTS

The results showed that compared with healthy controls, the species abundance index of intestinal flora in patients with pancreatic cancer was increased (P < 0.05), and the number of beneficial bacteria at the genus level was reduced (P < 0.05). Compared with patients with chronic pancreatitis, the expression levels of CA242 and CA199 in the serum of patients with pancreatic cancer were increased (P < 0.05). The bacterial richness index of tumor microorganisms in patients with pancreatic cancer increased, while the diversity index decreased(P < 0.05). Furthermore, there was a change in the species composition at the genus level. Additionally, the expression level of CA242 was found to be significantly positively correlated with the relative abundance of Acinetobacter(P < 0.05).

CONCLUSION

Over all, the expression levels of serum tumor markers CA242 and CA19-9 in patients with pancreatic cancer are increased, while the beneficial bacteria in the intestine and tumor microenvironment are reduced and pathogenic bacteria are increased. Acinetobacter is a specific bacterial genus highly expressed in pancreatic cancer tissue.

Quantitative evaluation of gut microbiota composition in pancreatic cancer: A pooled study

BACKGROUND

Prior research has demonstrated a positive association between the composition of gut microbiota and the incidence of pancreatic cancer. Nevertheless, a thorough quantitative and systematic evaluation of the distinct properties of gut microbiota in individuals diagnosed with pancreatic cancer has yet to be conducted. The objective of this study is to examine alterations in the diversity of intestinal microbiota in individuals diagnosed with pancreatic cancer.

METHODS

Search for relevant literature published before July 2023 in 4 databases: PubMed, Embase, Web of Science, and Cochrane Library, without any language restrictions.

RESULTS

A total of 12 studies were included, including 535 patients with pancreatic cancer and 677 healthy controls. Analysis was conducted on 6 phyla, 16 genera, and 6 species. The study found significant and distinctive changes in the α-diversity of gut microbiota, as well as in the relative abundance of multiple gut bacterial groups at the phylum, genus, and species levels in pancreatic cancer patients.

CONCLUSION

Overall, there are certain characteristic changes in the gut microbiota of pancreatic cancer patients. However, further research is warranted to elucidate the specific mechanism of action and the potential for treatment.

Prevotella copri exhausts intrinsic indole-3-pyruvic acid in the host to promote breast cancer progression: inactivation of AMPK via UHRF1-mediated negative regulation

Emerging evidence has revealed the novel role of gut microbiota in the development of cancer. The characteristics of function and composition in the gut microbiota of patients with breast cancer patients has been reported, however the detailed causation between gut microbiota and breast cancer remains uncertain. In the present study, 16S rRNA sequencing revealed that Prevotella, particularly the dominant species Prevotella copri, is significantly enriched and prevalent in gut microbiota of breast cancer patients. Prior-oral administration of P. copri could promote breast cancer growth in specific pathogen-free mice and germ-free mice, accompanied with sharp reduction of indole-3-pyruvic acid (IPyA). Mechanistically, the present of excessive P. copri consumed a large amount of tryptophan (Trp), thus hampering the physiological accumulation of IPyA in the host. Our results revealed that IPyA is an intrinsic anti-cancer reagent in the host at physiological level. Briefly, IPyA directly suppressed the transcription of UHRF1, following by the declined UHRF1 and PP2A C in nucleus, thus inhibiting the phosphorylation of AMPK, which is just opposite to the cancer promoting effect of P. copri. Therefore, the exhaustion of IPyA by excessive P. copri strengthens the UHRF1-mediated negative control to inactivated the energy-controlling AMPK signaling pathway to promote tumor growth, which was indicated by the alternation in pattern of protein expression and DNA methylation. Our findings, for the first time, highlighted P. copri as a risk factor for the progression of breast cancer.

Gut microbiota controls the development of chronic pancreatitis: A critical role of short-chain fatty acids-producing Gram-positive bacteria

Chronic pancreatitis (CP) is a progressive and irreversible fibroinflammatory disorder, accompanied by pancreatic exocrine insufficiency and dysregulated gut microbiota. Recently, accumulating evidence has supported a correlation between gut dysbiosis and CP development. However, whether gut microbiota dysbiosis contributes to CP pathogenesis remains unclear. Herein, an experimental CP was induced by repeated high-dose caerulein injections. The broad-spectrum antibiotics (ABX) and ABX targeting Gram-positive (G+) or Gram-negative bacteria (G-) were applied to explore the specific roles of these bacteria. Gut dysbiosis was observed in both mice and in CP patients, which was accompanied by a sharply reduced abundance for short-chain fatty acids (SCFAs)-producers, especially G+ bacteria. Broad-spectrum ABX exacerbated the severity of CP, as evidenced by aggravated pancreatic fibrosis and gut dysbiosis, especially the depletion of SCFAs-producing G+ bacteria. Additionally, depletion of SCFAs-producing G+ bacteria rather than G- bacteria intensified CP progression independent of TLR4, which was attenuated by supplementation with exogenous SCFAs. Finally, SCFAs modulated pancreatic fibrosis through inhibition of macrophage infiltration and M2 phenotype switching. The study supports a critical role for SCFAs-producing G+ bacteria in CP. Therefore, modulation of dietary-derived SCFAs or G+ SCFAs-producing bacteria may be considered a novel interventive approach for the management of CP.

Composition and functional profiles of gut microbiota reflect the treatment stage, severity, and etiology of acute pancreatitis

Acute pancreatitis (AP) is a type of digestive system disease with high mortality. Previous studies have shown that gut microbiota can participate in developing and treating acute pancreatitis by affecting the host's metabolism. In this study, we followed 20 AP patients to generate longitudinal gut microbiota profiles and activity during disease (before treatment, on the third day of treatment, and 1 month after discharge). We analyzed species composition and metabolic pathways' changes across the treatment phase, severity, and etiology. The diversity of the gut microbiome of patients with AP did not show much variation with treatment. In contrast, the metabolic functions of the gut microbiota, such as the essential chemical reactions that produce energy and maintain life, were partially reinstated after treatment. The severe AP (SAP) patients contained less beneficial bacteria (i.e., Bacteroides xylanisolvens, Clostridium lavalense, and Roseburia inulinivorans) and weaker sugar degradation function than mild AP patients before treatment. Moreover, etiology was one of the drivers of gut microbiome composition and explained the 3.54% variation in species' relative abundance. The relative abundance of pathways related to lipid synthesis was higher in the gut of hyperlipidemia AP patients than in biliary AP patients. The composition and functional profiles of the gut microbiota reflect the severity and etiology of AP. Otherwise, we also identified bacterial species associated with SAP, i.e., Oscillibacter sp. 57_20, Parabacteroides johnsonii, Bacteroides stercoris, Methanobrevibacter smithii, Ruminococcus lactaris, Coprococcus comes, and Dorea formicigenerans, which have the potential to identify the SAP at an early stage. IMPORTANCE Acute pancreatitis (AP) is a type of digestive system disease with high mortality. Previous studies have shown that gut microbiota can participate in the development and treatment of acute pancreatitis by affecting the host's metabolism. However, fewer studies acquired metagenomic sequencing data to associate species to functions intuitively and performed longitudinal analysis to explore how gut microbiota influences the development of AP. We followed 20 AP patients to generate longitudinal gut microbiota profiles and activity during disease and studied the differences in intestinal flora under different severities and etiologies. We have two findings. First, the gut microbiota profile has the potential to identify the severity and etiology of AP at an early stage. Second, gut microbiota likely acts synergistically in the development of AP. This study provides a reference for characterizing the driver flora of severe AP to identify the severity of acute pancreatitis at an early stage.

Association of ADRB2 gene polymorphisms and intestinal microbiota in Chinese Han adolescents

Gut microbiota are closely related to health, and the β2-adrenergic receptor (ADRB2) gene is associated with gastrointestinal diseases. However, little is known about the relationship between ADRB2 gene polymorphisms and intestinal microbiota. In the present study, we aimed to explore the relationship between ADRB2 gene polymorphisms and gut microbiota in Chinese Han adolescents. Data analysis showed that the relative abundance, PICRUSt function prediction, and Chao1 and ACE indices of gut microbiota were significantly different between males and females (P < 0.05). The rs1042711 was positively associated with the relative abundance of Actinobacteria, Coriobacteriia, Bifidobacteriales, Erysipelotrichi, and Erysipelotrichales. The rs12654778 was negatively associated with Bacilli, Lactobacillales, Bacteroidaceae, and Bacteroides. rs1042713 was positively associated with Lactobacillales and Bifidobacteriales. The rs1042717 was positively associated with Bifidobacteriales and negatively associated with Veillonellaceae. The rs1042719 was negatively associated with Erysipelotrichi and Erysipelotrichales and positively associated with Erysipelotrichi, Erysipelotrichales, Bifidobacteriales, and Ruminococcaceae in females. The rs1801704 was positively associated with Erysipelotrichi, Erysipelotrichales, Bifidobacteriales, Actinobacteria, Coriobacteriia, and Bifidobacteriales. The rs2053044 was positively associated with Ruminococcaceae, Dialister, Firmicutes, Clostridia, Clostridiales, Bifidobacteriales, and Faecalibacterium and negatively associated with Bacilli, Lactobacillales, Lachnospiraceae, and Porphyromonadaceae (P < 0.05). These results suggested that the relative abundance, diversity, and PICRUSt function predictions of male and female gut microbiomes differ significantly and that ADRB2 gene polymorphisms were associated with gut microbiome abundance in Chinese Han adolescents.

Carotenoids Diet: Digestion, Gut Microbiota Modulation, and Inflammatory Diseases

Several epidemiologic studies have found that consuming fruits and vegetables lowers the risk of getting a variety of chronic illnesses, including several types of cancers, cardiovascular diseases (CVDs), and bowel diseases. Although there is still debate over the bioactive components, various secondary plant metabolites have been linked to these positive health benefits. Many of these features have recently been connected to carotenoids and their metabolites' effects on intracellular signalling cascades, which influence gene expression and protein translation. Carotenoids are the most prevalent lipid-soluble phytochemicals in the human diet, are found in micromolar amounts in human serum, and are very susceptible to multiple oxidation and isomerisation reactions. The gastrointestinal delivery system, digestion processes, stability, and functionality of carotenoids, as well as their impact on the gut microbiota and how carotenoids may be effective modulators of oxidative stress and inflammatory pathways, are still lacking research advances. Although several pathways involved in carotenoids' bioactivity have been identified, future studies should focus on the carotenoids' relationships, related metabolites, and their effects on transcription factors and metabolism.

Microbiota Regulates Pancreatic Cancer Carcinogenesis through Altered Immune Response

The microbiota is present in many parts of the human body and plays essential roles. The most typical case is the occurrence and development of cancer. Pancreatic cancer (PC), one of the most aggressive and lethal types of cancer, has recently attracted the attention of researchers. Recent research has revealed that the microbiota regulates PC carcinogenesis via an altered immune response. Specifically, the microbiota, in several sites, including the oral cavity, gastrointestinal tract, and pancreatic tissue, along with the numerous small molecules and metabolites it produces, influences cancer progression and treatment by activating oncogenic signaling, enhancing oncogenic metabolic pathways, altering cancer cell proliferation, and triggering chronic inflammation that suppresses tumor immunity. Diagnostics and treatments based on or in combination with the microbiota offer novel insights to improve efficiency compared with existing therapies.

Gut Microbiome-Brain Alliance: A Landscape View into Mental and Gastrointestinal Health and Disorders

Gut microbiota includes a vast collection of microorganisms residing within the gastrointestinal tract. It is broadly recognized that the gut and brain are in constant bidirectional communication, of which gut microbiota and its metabolic production are a major component, and form the so-called gut microbiome-brain axis. Disturbances of microbiota homeostasis caused by imbalance in their functional composition and metabolic activities, known as dysbiosis, cause dysregulation of these pathways and trigger changes in the blood-brain barrier permeability, thereby causing pathological malfunctions, including neurological and functional gastrointestinal disorders. In turn, the brain can affect the structure and function of gut microbiota through the autonomic nervous system by regulating gut motility, intestinal transit and secretion, and gut permeability. Here, we examine data from the CAS Content Collection, the largest collection of published scientific information, and analyze the publication landscape of recent research. We review the advances in knowledge related to the human gut microbiome, its complexity and functionality, its communication with the central nervous system, and the effect of the gut microbiome-brain axis on mental and gut health. We discuss correlations between gut microbiota composition and various diseases, specifically gastrointestinal and mental disorders. We also explore gut microbiota metabolites with regard to their impact on the brain and gut function and associated diseases. Finally, we assess clinical applications of gut-microbiota-related substances and metabolites with their development pipelines. We hope this review can serve as a useful resource in understanding the current knowledge on this emerging field in an effort to further solving of the remaining challenges and fulfilling its potential.

[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.

Fecal microbiota transplantation inhibits colorectal cancer progression: Reversing intestinal microbial dysbiosis to enhance anti-cancer immune responses

Many lines of evidence demonstrate the associations of colorectal cancer (CRC) with intestinal microbial dysbiosis. Recent reports have suggested that maintaining the homeostasis of microbiota and host might be beneficial to CRC patients, but the underlying mechanisms remain unclear. In this study, we established a CRC mouse model of microbial dysbiosis and evaluated the effects of fecal microbiota transplantation (FMT) on CRC progression. Azomethane and dextran sodium sulfate were used to induce CRC and microbial dysbiosis in mice. Intestinal microbes from healthy mice were transferred to CRC mice by enema. The vastly disordered gut microbiota of CRC mice was largely reversed by FMT. Intestinal microbiota from normal mice effectively suppressed cancer progression as assessed by measuring the diameter and number of cancerous foci and significantly prolonged survival of the CRC mice. In the intestine of mice that had received FMT, there were massive infiltration of immune cells, including CD8⁺ T and CD49b⁺ NK, which is able to directly kill cancer cells. Moreover, the accumulation of immunosuppressive cells, Foxp3⁺ Treg cells, seen in the CRC mice was much reduced after FMT. Additionally, FMT regulated the expressions of inflammatory cytokines in CRC mice, including down-regulation of IL1a, IL6, IL12a, IL12b, IL17a, and elevation of IL10. These cytokines were positively correlated with Azospirillum_sp._47_25, Clostridium_sensu_stricto_1, the E. coli complex, Akkermansia, Turicibacter, and negatively correlated with Muribaculum, Anaeroplasma, Candidatus_Arthromitus, and Candidatus Saccharimonas. Furthermore, the repressed expressions of TGFb, STAT3 and elevated expressions of TNFa, IFNg, CXCR4 together promoted the anti-cancer efficacy. Their expressions were positively correlated with Odoribacter, Lachnospiraceae-UCG-006, Desulfovibrio, and negatively correlated with Alloprevotella, Ruminococcaceae UCG-014, Ruminiclostridium, Prevotellaceae UCG-001 and Oscillibacter. Our studies indicate that FMT inhibits the development of CRC by reversing gut microbial disorder, ameliorating excessive intestinal inflammation and cooperating with anti-cancer immune responses.

Altered gut microbiota in the early stage of acute pancreatitis were related to the occurrence of acute respiratory distress syndrome

Background

Acute respiratory distress syndrome (ARDS) is the most common cause of organ failure in acute pancreatitis (AP) patients, which associated with high mortality. Specific changes in the gut microbiota have been shown to influence progression of acute pancreatitis. We aimed to determine whether early alterations in the gut microbiota is related to and could predict ARDS occurrence in AP patients.

Methods

In this study, we performed 16S rRNA sequencing analysis in 65 AP patients and 20 healthy volunteers. The AP patients were further divided into two groups: 26 AP-ARDS patients and 39 AP-nonARDS patients based on ARDS occurrence during hospitalization.

Results

Our results showed that the AP-ARDS patients exhibited specific changes in gut microbiota composition and function as compared to subjects of AP-nonARDS group. Higher abundances of Proteobacteria phylum, Enterobacteriaceae family, Escherichia-Shigella genus, and Klebsiella pneumoniae, but lower abundances of Bifidobacterium genus were found in AP-ARDS group compared with AP-nonARDS groups. Random forest modelling analysis revealed that the Escherichia-shigella genus was effective to distinguish AP-ARDS from AP-nonARDS, which could predict ARDS occurrence in AP patients.

Conclusions

Our study revealed that alterations of gut microbiota in AP patients on admission were associated with ARDS occurrence after hospitalization, indicating a potential predictive and pathogenic role of gut microbiota in the development of ARDS in AP patients.

Adlay (Coix lacryma-jobi L.) Polyphenol Improves Hepatic Glucose and Lipid Homeostasis through Regulating Intestinal Flora via AMPK Pathway

SCOPE

Non-alcoholic fatty liver disease (NAFLD) is a type of metabolic syndrome characterized of abnormal lipid deposition in the liver. Adlay polyphenol (AP), an effective component extracted from Coix lacryma-jobi L., has been reported that it can be used as a dietary supplement to prevent NAFLD. In this study, the mechanism and action of AP on lipid metabolism and regulation of intestinal flora are investigated.

METHODS AND RESULTS

AP significantly decreases the lipid accumulation in free fatty acid-treated HepG2 cells. Western blot results indicate that AP improves lipid metabolism via activating the p-AMPK/p-ACC pathway. In vivo experiments show AP treatment significantly decreases the body weight, liver weight, hepatic triglyceride, and total cholesterol contents, as well as the serum glucose levels in high fat diet-fed mice, which may affect lipid accumulation by activating AMPK pathway and changing intestinal bacterial communities and intestinal microbiome metabolism.

CONCLUSION

AP can be used as a food supplement for improving lipid metabolic dysfunction and reducing the incidence of metabolic diseases.

Role of Micronutrients and Gut Microbiota-Derived Metabolites in COVID-19 Recovery

A balanced and varied diet provides diverse beneficial effects on health, such as adequate micronutrient availability and a gut microbiome in homeostasis. Besides their participation in biochemical processes as cofactors and coenzymes, vitamins and minerals have an immunoregulatory function; meanwhile, gut microbiota and its metabolites coordinate directly and indirectly the cell response through the interaction with the host receptors. Malnourishment is a crucial risk factor for several pathologies, and its involvement during the Coronavirus Disease 2019 pandemic has been reported. This pandemic has caused a significant decline in the worldwide population, especially those with chronic diseases, reduced physical activity, and elder age. Diet and gut microbiota composition are probable causes for this susceptibility, and its supplementation can play a role in reestablishing microbial homeostasis and improving immunity response against Coronavirus Disease 2019 infection and recovery. This study reviews the role of micronutrients and microbiomes in the risk of infection, the severity of disease, and the Coronavirus Disease 2019 sequelae.

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.

Functions of Gut Microbiota Metabolites, Current Status and Future Perspectives

Gut microbiota, a collection of microorganisms that live within gastrointestinal tract, provides crucial signaling metabolites for the physiological of hosts. In healthy state, gut microbiota metabolites are helpful for maintaining the basic functions of hosts, whereas disturbed production of these metabolites can lead to numerous diseases such as metabolic diseases, cardiovascular diseases, gastrointestinal diseases, neurodegenerative diseases, and cancer. Although there are many reviews about the specific mechanisms of gut microbiota metabolites on specific diseases, there is no comprehensive summarization of the functions of these metabolites. In this Opinion, we discuss the knowledge of gut microbiota metabolites including the types of gut microbiota metabolites and their ways acting on targets. In addition, we summarize their physiological and pathologic functions in health and diseases, such as shaping the composition of gut microbiota and acting as nutrition. This paper can be helpful for understanding the roles of gut microbiota metabolites and thus provide guidance for developing suitable therapeutic strategies to combat microbial-driven diseases and improve health.

Recent advances of gut microbiota in chronic kidney disease patients

Chronic kidney disease (CKD) is a worldwide public health issue and has ultimately progressed to an end-stage renal disease that requires life-long dialysis or renal transplantation. However, the underlying molecular mechanism of these pathological development and progression remains to be fully understood. The human gut microbiota is made up of approximately 100 trillion microbial cells including anaerobic and aerobic species. In recent years, more and more evidence has indicated a clear association between dysbiosis of gut microbiota and CKD including immunoglobulin A (IgA) nephropathy, diabetic kidney disease, membranous nephropathy, chronic renal failure and end-stage renal disease. The current review describes gut microbial dysbiosis and metabolites in patients with CKD thus helping to understand human disease. Treatment with prebiotics, probiotics and natural products can attenuate CKD through improving dysbiosis of gut microbiota, indicating a novel intervention strategy in patients with CKD. This review also discusses therapeutic options, such as prebiotics, probiotics and natural products, for targeting dysbiosis of gut microbiota in patients to provide more specific concept-driven therapy strategy for CKD treatment.

Sequestration of Intestinal Acidic Toxins by Cationic Resin Attenuates Pancreatic Cancer Progression through Promoting Autophagic Flux for YAP Degradation

Simple Summary

Annually, more than 450,000 people are diagnosed with pancreatic cancer worldwide with over 430,000 mortalities. Pancreatic ductal carcinoma (PDAC) accounts for around 80% of pancreatic cancer cases with an extremely high mortality rate. Emerging research has demonstrated that gut dysbiosis is closely associated with pancreatic cancer, while the underlying mechanisms remain elusive. In this study, we found that elevated levels of endotoxin (LPS) and bile acids were associated with malignant progression in Kras-driven pancreatic cancer mice. Importantly, oral administration of cationic resins to sequestrate intestinal endotoxins and bile acids efficiently attenuated tumor progression. Thus, sequestration of intestinal acidic toxins by oral administration of cationic resins may have potential as an intervention strategy for pancreatic malignancy.

Abstract

Pancreatic cancer is driven by risk factors such as diabetes and chronic pancreatic injury, which are further associated with gut dysbiosis. Intestinal toxins such as bile acids and bacterial endotoxin (LPS), in excess and persistence, can provoke chronic inflammation and tumorigenesis. Of interest is that many intestinal toxins are negatively charged acidic components in essence, which prompted us to test whether oral administration of cationic resin can deplete intestinal toxins and ameliorate pancreatic cancer. Here, we found that increased plasma levels of endotoxin and bile acids in Pdx1-Cre: LSL-Kras^G12D/+ mice were associated with the transformation of the pancreatic ductal carcinoma (PDAC) state. Common bile-duct-ligation or LPS injection impeded autolysosomal flux, leading to Yap accumulation and malignant transformation. Conversely, oral administration of cholestyramine to sequestrate intestinal endotoxin and bile acids resumed autolysosomal flux for Yap degradation and attenuated metastatic incidence. Conversely, chloroquine treatment impaired autolysosomal flux and exacerbated malignance, showing jeopardization of p62/ Sqxtm1 turnover, leading to Yap accumulation, which is also consistent with overexpression of cystatin A (CSTA) in situ with pancreatic cancer cells and metastatic tumor. At cellular levels, chenodeoxycholic acid or LPS treatment activated the ligand–receptor-mediated AKT-mTOR pathway, resulting in autophagy-lysosomal stress for YAP accumulation and cellular dissemination. Thus, this work indicates a potential new strategy for intervention of pancreatic metastasis through sequestration of intestinal acidic toxins by oral administration of cationic resins.

Neutrophil Extracellular Traps Caused by Gut Leakage Trigger the Autoimmune Response in Nonobese Diabetic Mice

Increased formation of neutrophil extracellular traps (NETs) is associated with gut leakage in type 1 diabetes (T1D). To explore the mechanism of how enteropathy exacerbated by NETs triggers pancreatic autoimmunity in T1D, we carried out a correlation analysis for NET formation with gut barrier functions and autoimmunity in nonobese diabetic (NOD) mice. Inducing chronic colitis or knocking out of peptidyl arginine deiminase type 4 (PAD4) in NOD mice were used to further study the effect of NET formation on the progression of T1D. Microbial alterations in Deferribacteres and Proteobacteria, along with the loss of gut barrier function, were found to be associated with increased endotoxin and abnormal formation of NETs in NOD mice. Both DSS-induced colitis and knockout of PAD4 in NOD mice indicated that PAD4-dependent NET formation was involved in the aggravation of gut barrier dysfunction, the production of autoantibodies, and the activation of enteric autoimmune T cells, which then migrated to pancreatic lymph nodes (PLNs) and caused self-damage. The current study thus provides evidence that PAD4-dependent NET formation is engaged in leaky gut triggering pancreatic autoimmunity and suggests that either degradation of NETs or inhibition of NET formation may be helpful for innovative therapeutic interventions in T1D.

Bruceae Fructus Oil Inhibits Triple-Negative Breast Cancer by Restraining Autophagy: Dependence on the Gut Microbiota-Mediated Amino Acid Regulation

Triple-negative breast cancer (TNBC) has been acknowledged as an aggressive disease with worst prognosis, which requires endeavor to develop novel therapeutic agents. Bruceae fructus oil (BO), a vegetable oil derived from the fruit of Brucea javanica (L.) Merr., is an approved marketable drug for the treatment of cancer in China for several decades. Despite that the anti–breast cancer activity of several quassinoids derived from B. javanica has been found, it was the first time that the potential of BO against TNBC was revealed. Although BO had no cytotoxicity on TNBC cell lines in vitro, the oral administration of BO exhibited a gut microbiota–dependent tumor suppression without toxicity on the non-targeted organs in vivo. By metagenomics and untargeted metabolomics, it was found that BO not only altered the composition and amino acid metabolism function of gut microbiota but also regulated the host’s amino acid profile, which was in accordance with the metabolism alternation in gut microbiota. Moreover, the activity of mTOR in tumor was promoted by BO treatment as indicated by the phosphorylation of 4E-binding protein 1 (4E-BP1) and ribosomal protein S6, and hyper-autophagy was consequently restrained. By contrast, the failure of tumor suppression by BO under pseudo germ-free (PGF) condition came with indistinctive changes in autophagy and mTOR activity, implying the critical role of the gut microbiota in BO’s anticancer activity. The present study highlighted a promising application of BO against breast cancer with novel efficacy and safety.