Butyrate enemas improve intestinal anastomotic strength in a rat model

Gut resistome profiling reveals high diversity and fluctuations in pancreatic cancer cohorts

Background

Pancreatic cancer is one of the deadliest cancer, with a 5-year overall survival rate of 11%. Unfortunately, most patients are diagnosed with advanced stage by the time they present with symptoms. In the past decade, microbiome studies have explored the association of pancreatic cancer with the human oral and gut microbiomes. However, the gut microbial antibiotic resistance genes profiling of pancreatic cancer patients was never reported compared to that of the healthy cohort.

Results

In this study, we addressed the gut microbial antibiotic resistance genes profile using the metagenomic data from two online public pancreatic cancer cohorts. We found a high degree of data concordance between the two cohorts, which can therefore be used for cross-sectional comparisons. Meanwhile, we used two strategies to predict antibiotic resistance genes and compared the advantages and disadvantages of these two approaches. We also constructed microbe-antibiotic resistance gene networks and found that most of the hub nodes in the networks were antibiotic resistance genes.

Conclusions

In summary, we describe the panorama of antibiotic resistance genes in the gut microbes of patients with pancreatic cancer. We hope that our study will provide new perspectives on treatment options for the disease.

Microbiota-Gastric Cancer Interactions and the Potential Influence of Nutritional Therapies

Gastric cancer (GC) is one of the most common causes of cancer deaths, and GC treatments represent a large area of research. Although initially regarded as a sterile organ and unsuitable for microbial communities, the discovery of Helicobacter pylori made us realize that some microbes can colonize the stomach. In recent years, growing interest in gastric bacteria has expanded to the gut microbiota and, more recently, to the oral microbiota. Indeed, the oral-gastric-gut microbiota axis may play a crucial role in maintaining homeostasis, while changes in microbiota composition in GC patients can influence clinical outcomes. On the one hand, the microbiota and its metabolites may significantly influence the progression of GC, while anti-GC treatments such as gastrectomy and chemotherapy may significantly impact the oral-gastric-gut microbiota axis of GC patients. In this context, the role of nutritional therapies, including diet, prebiotics, and probiotics, in treating GC should not be underestimated. Wit this review, we aim to highlight the main role of the gastric, oral, and gut microbiota in GC onset and progression, representing potential future biomarkers for early GC detection and a target for efficient nutritional therapies during the course of GC.

Diet-induced shifts in the gut microbiota influence anastomotic healing in a murine model of colonic surgery

Host diet and gut microbiota interact to contribute to perioperative complications, including anastomotic leak (AL). Using a murine surgical model of colonic anastomosis, we investigated how diet and fecal microbial transplantation (FMT) impacted the intestinal microbiota and if a predictive signature for AL could be determined. We hypothesized that a Western diet (WD) would impact gut microbial composition and that the resulting dysbiosis would correlate with increased rates of AL, while FMT from healthy, lean diet (LD) donors would reduce the risk of AL. Furthermore, we predicted that surgical outcomes would allow for the development of a microbial preclinical translational tool to identify AL. Here, we show that AL is associated with a dysbiotic microbial community characterized by increased levels of Bacteroides and Akkermansia. We identified several key taxa that were associated with leak formation, and developed an index based on the ratio of bacteria associated with the absence and presence of leak. We also highlight a modifiable connection between diet, microbiota, and anastomotic healing, potentially paving the way for perioperative modulation by microbiota-targeted therapeutics to reduce AL.

Enhancing intestinal anastomotic healing using butyrate: Systematic review and meta-analysis of experimental animal studies

BACKGROUND

Despite advancements in surgical technique and perioperative care, intestinal anastomoses still have a 10-15 per cent risk of leakage, which results in considerable morbidity and/or mortality. Recent animal studies have suggested that administration of butyrate to the anastomotic site results in enhanced anastomotic strength, which may prevent leakage. This systematic review and meta-analysis summarises current evidence concerning the effect of butyrate administration on anastomotic healing and will form a scientific basis for the development of new research into this subject.

METHODS

Animal studies on the effect of butyrate-based interventions in models of intestinal anastomotic healing were systematically retrieved from online databases. Bibliographical data, study characteristics and outcome data were extracted, and internal validity of the studies was assessed. Outcomes studied through meta-analysis concerned: anastomotic strength, anastomotic leakage, collagen metabolism and general histologic parameters of wound healing.

RESULTS

A comprehensive search and selection identified 19 relevant studies containing 41 individual comparisons. Design and conduct of most experiments were poorly reported resulting in an unclear risk of bias. Meta-analyses showed that butyrate administration significantly increases anastomotic strength (SMD 1.24, 0.88 to 1.61), collagen synthesis (SMD 1.44, 0.72 to 2.15) and collagen maturation, making anastomoses less prone to leakage in the early postoperative period (OR 0.37, 0.15 to 0.93).

CONCLUSION

This systematic review and meta-analysis shows that there is potential ground to investigate the use of butyrate in clinical trials to prevent anastomotic leakage in intestinal surgery. However, more research is necessary to define the best application form, dosage and administration route.

The Influence of the Microbiome on Anastomotic Leak

Anastomotic leak, defined by the International Study Group of Rectal Cancer as "a communication between the intra- and extraluminal compartments owing to a defect of the integrity of the intestinal wall at the anastomosis," is one of the most devastating complications in colorectal surgery. Much work has been done to identify causes of leak; however, despite advances in surgical technique, the prevalence of anastomotic leak has remained at around 11%. The potential causative role of bacteria in the etiopathology of anastomotic leak was established in the 1950s. More recently, alterations in the colonic microbiome have been shown to affect rates of anastomotic leak. Multiple perioperative factors that alter the homeostasis of the gut microbiota community structure and function have been linked to anastomotic leak after colorectal surgery. Here, we discuss the role of diet, radiation, bowel preparation, medications including nonsteroidal anti-inflammatory drugs, morphine, and antibiotics, and specific microbial pathways that have been implicated in anastomotic leak via their effects on the microbiome.

The Colorectal Anastomosis: A Timeless Challenge

Colorectal anastomosis is a sophisticated problem that demands an elaborate discussion and an elegant solution. "Those who forget the past are condemned to repeat it." George Santayana, Life of Reason , 1905.

Dietary modulation of gut microbiota in patients with colorectal cancer undergoing surgery: A review

Colorectal cancer (CRC) is the third most frequent malignancy and the second cause of cancer death worldwide. Several factors have been postulated to be involved in CRC pathophysiology, including physical inactivity, unhealthy dietary habits, obesity, and the gut microbiota. Emerging data suggest that the microbiome may play a key role in CRC prognosis and derived complications in patients undergoing colorectal surgery. On the other hand, dietary intervention has been demonstrated to be able to induce significant changes in the gut microbiota and related metabolites in different conditions; therefore, the manipulation of gut microbiota through dietary intervention may constitute a useful approach to improve perioperative dysbiosis and post-surgical outcomes in patients with CRC. In this article, we review the role of the gut microbiota in CRC surgery complications and the potential therapeutic modulation of gut microbiome through nutritional intervention in patients with CRC undergoing surgery.

The Immunomodulatory Functions of Butyrate

The gastrointestinal (GI) system contains many different types of immune cells, making it a key immune organ system in the human body. In the last decade, our knowledge has substantially expanded regarding our understanding of the gut microbiome and its complex interaction with the gut immune system. Short chain fatty acids (SCFA), and specifically butyrate, play an important role in mediating the effects of the gut microbiome on local and systemic immunity. Gut microbial alterations and depletion of luminal butyrate have been well documented in the literature for a number of systemic and GI inflammatory disorders. Although a substantial knowledge gap exists requiring the need for further investigations to determine cause and effect, there is heightened interest in developing immunomodulatory therapies by means of reprogramming of gut microbiome or by supplementing its beneficial metabolites, such as butyrate. In the current review, we discuss the role of endogenous butyrate in the inflammatory response and maintaining immune homeostasis within the intestine. We also present the experimental models and human studies which explore therapeutic potential of butyrate supplementation in inflammatory conditions associated with butyrate depletion.

The Association of Gut Microbiota and Complications in Gastrointestinal-Cancer Therapies

The therapy of gastrointestinal carcinomas includes surgery, chemo- or immunotherapy, and radiation with diverse complications such as surgical-site infection and enteritis. In recent years, the microbiome’s influence on different diseases and complications has been studied in more detail using methods such as next-generation sequencing. Due to the relatively simple collectivisation, the gut microbiome is the best-studied so far. While certain bacteria are sometimes associated with one particular complication, it is often just the loss of alpha diversity linked together. Among others, a strong influence of Fusobacterium nucleatum on the effectiveness of chemotherapies is demonstrated. External factors such as diet or specific medications can also predispose to dysbiosis and lead to complications. In addition, there are attempts to treat developed dysbiosis, such as faecal microbiota transplant or probiotics. In the future, the underlying microbiome should be investigated in more detail for a better understanding of the precipitating factors of a complication with specific therapeutic options.

The role of butyrate in surgical and oncological outcomes in colorectal cancer

Butyrate is a short-chain fatty acid produced by colonic gut bacteria as a result of fermentation of dietary fibers. In the colon, butyrate is a major energy substrate and contributes to the nutritional support and proliferation of a healthy mucosa. It also promotes the intestinal barrier function by enhancing mucus production and tight junctions. In addition to its pro-proliferative effect in healthy colonocytes, butyrate inhibits the proliferation of cancer cells. The antineoplastic effect of butyrate is associated with the inhibitory effect of butyrate on histone deacetylase (HDAC) enzymes, which promote carcinogenesis. Due to the metabolic shift of cancer cells toward glycolysis, unused butyrate accumulates and inhibits procarcinogenic HDACs. In addition, recent studies suggest that butyrate may improve the healing of colonic tissue after surgery in animal models, specifically at the site of reconnection of colonic ends, anastomosis, after surgical resection. Here, we review current evidence on the impact of butyrate on epithelial integrity and colorectal cancer and present current knowledge on data that support its potential applications in surgical practice.

The role of the microbiome in drug resistance in gastrointestinal cancers

Introduction: The microbiota is recognized for its impact on both human health and disease. The human microbiota is made up of trillions of cells, including bacteria, viruses, and fungi. The largest population of microbes reside in the gut, prompting research for better understanding of the impact of gastrointestinal microbiota in different diseases. Evidence from numerous studies has pointed out the role of commensal microbes as key determinants of cancer pathogenesis. Moreover, gut microbiota may play an important role in chemoresistance; consequently, this knowledge might be important for novel strategies to improve anticancer treatment efficacy.Areas covered: We describe the role of microbiota in different gastrointestinal cancer types (esophageal, gastric, colorectal, hepatocellular and pancreatic-biliary tract cancers). Moreover, we analyzed the impact of the microbiota on resistance to anticancer therapies, and, lastly, we focused on possibilities of microbiota modulation to enhance anticancer therapy efficacy.Expert opinion: Increasing evidence shows that gut microbiota might influence resistance to anticancer treatment, including conventional chemotherapy, immunotherapy, radiotherapy, and surgery. Therefore, a better knowledge of gut microbiota and its interactions with anticancer drugs will enable us to develop novel anticancer treatment strategies and subsequently improve the cancer patients' outcome.

Intestinal Microbiota: A Novel Target to Improve Anti-Tumor Treatment?

Recently, preclinical and clinical studies targeting several types of cancer strongly supported the key role of the gut microbiota in the modulation of host response to anti-tumoral therapies such as chemotherapy, immunotherapy, radiotherapy and even surgery. Intestinal microbiome has been shown to participate in the resistance to a wide range of anticancer treatments by direct interaction with the treatment or by indirectly stimulating host response through immunomodulation. Interestingly, these effects were described on colorectal cancer but also in other types of malignancies. In addition to their role in therapy efficacy, gut microbiota could also impact side effects induced by anticancer treatments. In the first part of this review, we summarized the role of the gut microbiome on the efficacy and side effects of various anticancer treatments and underlying mechanisms. In the second part, we described the new microbiota-targeting strategies, such as probiotics and prebiotics, antibiotics, fecal microbiota transplantation and physical activity, which could be effective adjuvant therapies developed in order to improve anticancer therapeutic efficiency.

Reducing anastomotic leak in colorectal surgery: The old dogmas and the new challenges

Anastomotic leak (AL) constitutes a significant issue in colorectal surgery, and its incidence has remained stable over the last years. The use of intra-abdominal drain or the use of mechanical bowel preparation alone have been proven to be useless in preventing AL and should be abandoned. The role or oral antibiotics preparation regimens should be clarified and compared to other routes of administration, such as the intravenous route or enema. In parallel, preoperative antibiotherapy should aim at targeting collagenase-inducing pathogens, as identified by the microbiome analysis. AL can be further reduced by fluorescence angiography, which leads to significant intraoperative changes in surgical strategies. Implementation of fluorescence angiography should be encouraged. Progress made in AL comprehension and prevention might probably allow reducing the rate of diverting stoma and conduct to a revision of its indications.

The Microbiome-Host Interaction as a Potential Driver of Anastomotic Leak

PURPOSE OF REVIEW

The goal of this paper is to review current literature on the gut microbiome within the context of host response to surgery and subsequent risk of developing complications, particularly anastomotic leak. We provide background on the relationship between host and gut microbiota with description of the role of the intestinal mucus layer as an important regulator of host health.

RECENT FINDINGS

Despite improvements in surgical technique and adherence to the tenets of creating a tension-free anastomosis with adequate blood flow, the surgical community has been unable to decrease rates of anastomotic leak using the current paradigm. Rather than adhere to empirical strategies of decontamination, it is imperative to focus on the interaction between the human host and the gut microbiota that live within us. The gut microbiome has been found to play a potential role in development of post-operative complications, including but not limited to anastomotic leak. Evidence suggests that peri-operative interventions may have a role in instigating or mitigating the impact of the gut microbiota via disruption of the protective mucus layer, use of multiple medications, and activation of virulence factors. The microbiome plays a potential role in the development of surgical complications and can be modulated by peri-operative interventions. As such, further research into this relationship is urgently needed.

Enhanced anastomotic healing by Daikenchuto (TJ-100) in rats

Daikenchuto (DKT), a traditional Japanese medicine, is widely used to treat various gastrointestinal disorders. This study aimed to investigate whether DKT could promote the anastomotic healing in a rat model. Pedicled colonic segments were made in left colon by ligation of the feeding arteries, and then intestinal continuity was restored. Colonic blood flow was analyzed by using ICG fluorescence imaging: Fmax, Tmax, T1/2, and Slope were calculated. Anastomotic leakage (AL) was found in 6 of 19 rats (31.6%) in the control group, whereas in 1 of 16 rats (6.2%) in the DKT group. The Fmax and Slope of DKT group were significantly higher than those of control group. DKT could promote the anastomotic healing, with the higher bursting pressure on postoperative day (POD) 2 and 5, the larger granulation thickness on POD 5, and neoangiogenesis on POD 5. Histological examination showed DKT exhibited a decreased inflammatory cell infiltration, enhanced fibroblast infiltration, and enhanced collagen density on POD 5. In the DKT group, the levels of TGFβ1 on POD 2 and VEGFα on POD5 were significantly higher, whereas the level of TNFα on POD 2 was significantly lower. Therefore, DKT could be effective for the prevention of AL following colorectal surgery.

Role of short-chain fatty acids in colonic inflammation, carcinogenesis, and mucosal protection and healing

Short-chain fatty acids (SCFAs), mainly acetate, propionate, and butyrate, produced by microbial fermentation of undigested food substances are believed to play a beneficial role in human gut health. Short-chain fatty acids influence colonic health through various mechanisms. In vitro and ex vivo studies show that SCFAs have anti-inflammatory and anticarcinogenic effects, play an important role in maintaining metabolic homeostasis in colonocytes, and protect colonocytes from external harm. Animal studies have found substantial positive effects of SCFAs or dietary fiber on colonic disease, but convincing evidence in humans is lacking. Most human intervention trials have been conducted in the context of inflammatory bowel disease. Only a limited number of those trials are of high quality, showing little or no favorable effect of SCFA treatment over placebo. Opportunities for future research include exploring the use of combination therapies with anti-inflammatory drugs, prebiotics, or probiotics; the use of prodrugs in the setting of carcinogenesis; or the direct application of SCFAs to improve mucosal healing after colonic surgery.

Functional mucous layer and healing of proximal colonic anastomoses in an experimental model

BACKGROUND

Anastomotic leakage (AL) is the most dreaded complication after colorectal surgery, causing high morbidity and mortality. Mucus is a first line of defence against external factors in the gastrointestinal tract. In this study, the structural mucus protein Muc2 was depleted in genetically engineered mice and the effect on healing of colonic anastomoses studied in an experimental model.

METHODS

Mice of different Muc2 genotypes were used in a proximal colonic AL model. Tissues were scored histologically for inflammation, bacterial translocation was determined by quantitative PCR of bacterial 16S ribosomal DNA, and epithelial cell damage was determined by assessing serum levels of intestinal fatty acid-binding protein.

RESULTS

Of 22 Muc2-deficient (Muc2^-/- ) mice, 20 developed AL, compared with seven of 22 control animals (P < 0·001). Control mice showed normal healing, whereas Muc2^-/- mice had more inflammation with less collagen deposition and neoangiogenesis. A tendency towards higher bacterial translocation was seen in mesenteric lymph nodes and spleen in Muc2^-/- mice. Intestinal fatty acid-binding protein levels were significantly higher in Muc2^-/- mice compared with controls (P = 0·011).

CONCLUSION

A functional mucous layer facilitates the healing of colonic anastomoses. Clinical relevance Colorectal anastomotic leakage remains the most dreaded complication after colorectal surgery. It is known that the aetiology of anastomotic leakage is multifactorial, and a role is suggested for the interaction between intraluminal content and mucosa. In this murine model of proximal colonic anastomotic leakage, the authors investigated the mucous layer at the intestinal mucosa, as the first line of defence, and found that a normal, functioning mucous layer is essential in the healing process of colonic anastomoses. Further research on anastomotic healing should focus on positively influencing the mucous layer to promote better postoperative recovery.

Impact of tissue adhesives on the prevention of anastomotic leakage of colonic anastomoses: an in vivo study

BACKGROUND

Tissue adhesives (TA) may be useful to strengthen colorectal anastomoses, thereby preventing anastomotic leakage (AL). Previous studies have identified cyanoacrylate (CA) TAs as the most promising colonic anastomotic sealants. This study investigates the protective effects of sealing colonic anastomoses with various CAs.

MATERIALS AND METHODS

Fifty-five Wistar rats underwent laparotomy and transection of the proximal colon. An anastomosis was created with 4 interrupted sutures followed by either application of Histoacryl Flexible, Omnex, Glubran 2, or no TA seal. An additional control group was included with a 12-suture anastomosis and no TA seal. After 7 days, the rats were sacrificed and scored for the presence of AL as the main outcome. Secondary outcomes were the occurrence of bowel obstruction, adhesions, and anastomotic bursting pressure. Histological evaluation was performed.

RESULTS

The highest AL rate was found in the Glubran 2 group (7/11), followed by the 4-sutures group without TA (5/11), and the Omnex group (5/11). Histoacryl Flexible showed the lowest AL rate (2/11). In the control group, only one rat showed signs of AL. Histologically, the highest influx of inflammatory cells was found in the 4-suture group without TA and for Omnex and Glubran 2. Histoacryl Flexible caused more mature collagen deposition when compared to the other TA groups.

CONCLUSIONS

Histoacryl Flexible showed the lowest leakage rate compared to the other TA groups and to the 4-suture control group. Glubran 2 showed the highest AL rate and a high inflammatory response. Histoacryl Flexible was associated with the presence of more mature collagen and seems to promote anastomotic healing.

Comparison of three different application routes of butyrate to improve colonic anastomotic strength in rats

INTRODUCTION

Despite extensive research, anastomotic leakage (AL) remains one of the most dreaded complications after colorectal surgery. Since butyrate enemas are known to enhance anastomotic healing, several administration routes have been explored in this study.

METHODS

Three intraluminal approaches involving butyrate were investigated: (1) butyrin-elucidating patch, (2) a single injection of hyaluronan-butyrate (HA-But) prior to construction of the proximal anastomosis and (3) rectal hyaluronan-butyrate (HA-But) enemas designed for distal anastomoses. The main outcome was AL and secondary outcomes were bursting pressure, histological analysis of the anastomosis, zymography to detect MMP activity and qPCR for gene expression of MMP2, MMP9, MUC2 and TFF3.

RESULTS

Neither the patches nor the injections led to a reduction of AL in experiments 1 and 2. In experiment 3, a significant reduction of AL was accomplished with the (HA-But) enema compared to the control group together with a higher bursting pressure. Histological analysis detected only an increased inflammation in experiment 2 in the hyaluronan injection group compared to the control group. No other differences were found regarding wound healing. Zymography identified a decreased proenzyme of MMP9 when HA-But was administered as a rectal enema. qPCR did not show any significant differences between groups in any experiment.

CONCLUSION

Butyrate enemas are effective in the enhancement of colonic anastomosis. Enhanced butyrate-based approaches designed to reduce AL in animal models for both proximal and distal anastomoses were not more effective than were butyrate enemas alone. Further research should focus on how exogenous butyrate can improve anastomotic healing after gastrointestinal surgery.

Emerging Trends in the Etiology, Prevention, and Treatment of Gastrointestinal Anastomotic Leakage

Anastomotic leaks represent one of the most alarming complications following any gastrointestinal anastomosis due to the substantial effects on post-operative morbidity and mortality of the patient with long-lasting effects on the functional and oncologic outcomes. There is a lack of consensus related to the definition of an anastomotic leak, with a variety of options for prevention and management. A number of patient-related and technical risk factors have been found to be associated with the development of an anastomotic leak and have inspired the development of various preventative measures and technologies. The International Multispecialty Anastomotic Leak Global Improvement Exchange group was convened to establish a consensus on the definition of an anastomotic leak as well as to discuss the various diagnostic, preventative, and management measures currently available.

Effects of Liver Resection on Hepatic Short-Chain Fatty Acid Metabolism in Humans

AIM

To determine whether acute loss of liver tissue affects hepatic short-chain fatty acid (SCFA) clearance.

METHODS

Blood was sampled from the radial artery, portal vein, and hepatic vein before and after hepatic resection in 30 patients undergoing partial liver resection. Plasma SCFA levels were measured by liquid chromatography-mass spectrometry. SCFA exchange across gut and liver was calculated from arteriovenous differences and plasma flow. Liver volume was estimated by CT liver volumetry.

RESULTS

The gut produced significant amounts of acetate, propionate, and butyrate (39.4±13.5, 6.2±1.3, and 9.5±2.6 μmol·kgbw-1·h-1), which did not change after partial hepatectomy (p = 0.67, p = 0.59 and p = 0.24). Hepatic propionate uptake did not differ significantly before and after resection (-6.4±1.4 vs. -8.4±1.5 μmol·kgbw-1·h-1, p = 0.49). Hepatic acetate and butyrate uptake increased significantly upon partial liver resection (acetate: -35.1±13.0 vs. -39.6±9.4 μmol·kgbw-1·h-1, p = 0.0011; butyrate: -9.9±2.7 vs. -11.5±2.4 μmol·kgbw-1·h-1, p = 0.0006). Arterial SCFA concentrations were not different before and after partial liver resection (acetate: 176.9±17.3 vs. 142.3±12.5 μmol/L, p = 0.18; propionate: 7.2±1.4 vs. 5.6±0.6 μmol/L, p = 0.38; butyrate: 4.3±0.7 vs. 3.6±0.6 μmol/L, p = 0.73).

CONCLUSION

The liver maintains its capacity to clear acetate, propionate, and butyrate from the portal blood upon acute loss of liver tissue.

Nutritional Aspects of Gastrointestinal Wound Healing

Significance: Although the wound healing cascade is similar in many tissues, in the gastrointestinal tract mucosal healing is critical for processes such as inflammatory bowel disease and ulcers and healing of the mucosa, submucosa, and serosal layers is needed for surgical anastomoses and for enterocutaneous fistula. Failure of wound healing can result in complications including infection, prolonged hospitalization, critical illness, organ failure, readmission, new or worsening enterocutaneous fistula, and even death. Recent Advances: Recent advances are relevant for the role of specific micronutrients, such as vitamin D, trace elements, and the interplay between molecules with pro- and antioxidant properties. Our understanding of the role of other small molecules, genes, proteins, and macronutrients is also rapidly changing. Recent work has elucidated relationships between oxidative stress, nutritional supplementation, and glucose metabolism. Thresholds have also been established to define adequate preoperative nutritional status. Critical Issues: Further work is needed to establish standards and definitions for measuring the extent of wound healing, particularly for inflammatory bowel disease and ulcers. In addition, a mounting body of evidence has determined the need for adequate preoperative nutritional supplementation for elective surgical procedures. Future Directions: A large portion of current work is restricted to model systems in rodents. Therefore, additional clinical and translational research is needed in this area to promote gastrointestinal wound healing in humans, particularly those suffering from critical illness, patients with enterocutaneous fistula, inflammatory bowel disease, and ulcers, and those undergoing surgical procedures.

Can specific nutrients stimulate bowel wound healing?

PURPOSE OF REVIEW

The purpose of review is to provide an overview on specific nutrients which play an important role in bowel wound healing, and to judge the efficacy of supplementation to derive recommendations for clinical practice.

RECENT FINDINGS

Glutamine, arginine, butyrate, ω-3 fatty acids, nucleotides, and several micronutrients are involved in bowel wound healing. However, with regard to clinical trials, the efficacy of supplementation of specific nutrients on bowel wound healing in patients with inflammatory bowel diseases has not been clarified yet. In patients undergoing colon surgery, sufficient evidence exists that the perioperative supply of an enteral immunomodulating formula enriched with arginine, nucleotides, and ω-3 fatty acids may improve intestinal wound healing, considering the lower risk of wound infections, wound dehiscence, and intra-abdominal abscess.

SUMMARY

Even if a range of nutrients are involved in bowel wound healing, only perioperative supply of an enteral immunomodulating formula to cancer patients undergoing colon surgery, can be recommended. Further randomized controlled trials are needed to elucidate the efficacy of individual nutrients on intestinal wound healing.

Gut Microbiota and Colorectal Surgery: Impact on Postoperative Complications

Colorectal anastomotic leakage is a dreaded complication after colorectal surgery and causes high morbidity and mortality. The pathophysiology of anastomotic healing remains unclear despite numerous studies. In this article, our aim is to provide different perspectives on what is known about the role of the gastrointestinal tract microbiome and its relation to anastomotic integrity.

International consensus statement regarding the use of animal models for research on anastomoses in the lower gastrointestinal tract

PURPOSE

This project aimed to reach consensus on the most appropriate animal models and outcome measures in research on anastomoses in the lower gastrointestinal tract (GIT). The physiology of anastomotic healing remains an important research topic in gastrointestinal surgery. Recent results from experimental studies are limited with regard to comparability and clinical translation.

METHODS

PubMed and EMBASE were searched for experimental studies investigating anastomotic healing in the lower GIT published between January 1, 2000 and December 31, 2014 to assess currently used models. All corresponding authors were invited for a Delphi-based analysis that consisted of two online survey rounds followed by a final online recommendation survey to reach consensus on the discussed topics.

RESULTS

Two hundred seventy-seven original articles were retrieved and 167 articles were included in the systematic review. Mice, rats, rabbits, pigs, and dogs are currently being used as animal models, with a large variety in surgical techniques and outcome measures. Forty-four corresponding authors participated in the Delphi analysis. In the first two rounds, 39/44 and 35/39 participants completed the survey. In the final meeting, 35 experts reached consensus on 76/122 items in six categories. Mouse, rat, and pig are considered appropriate animal models; rabbit and dog should be abandoned in research regarding bowel anastomoses. ARRIVE guidelines should be followed more strictly.

CONCLUSIONS

Consensus was reached on several recommendations for the use of animal models and outcome measurements in research on anastomoses of the lower GIT. Future research should take these suggestions into account to facilitate comparison and clinical translation of results.

Colorectal anastomotic healing: why the biological processes that lead to anastomotic leakage should be revealed prior to conducting intervention studies

BACKGROUND

Anastomotic leakage (AL) remains the most dreaded complication after colorectal surgery and causes high morbidity and mortality. The pathophysiology of AL remains unclear, despite numerous studies that have been conducted on animals and humans, probably due to the undetermined healing process of colorectal anastomoses. Increasing basic knowledge on this healing process may shed more light on causal factors of AL, and additionally reduce the quantity and accelerate the quality of experimental studies. In this debate article, our aim was to provide different perspectives on what is known about the colorectal healing process in relation to wound healing and AL.

DISCUSSION

Since knowledge on anastomotic healing is lacking, it remains difficult to conclude which factors are essential in preventing AL. This is essential information in the framework of humane animal research, where the focus should lie on Replacement, Reduction and Refinement (3Rs). While many researchers compare anastomotic healing with wound healing in the skin, there are substantial recognized differences, e.g. other collagen subtypes and different components involved. Based on our findings in literature as well as discussions with experts, we advocate stop considering anastomotic healing in the gastrointestinal tract and cutaneous healing as a similar process. Furthermore, intervention studies should at least address the anastomotic healing process in terms of histology and certain surrogate markers. Finally, the anastomotic healing process ought to be further elucidated - with modern techniques to achieve 3Rs in animal research--to provide starting points for potential interventions that can prevent AL.

Intraperitoneal administration of butyrate prevents the severity of acetic acid colitis in rats

Intrarectal infusion of butyrate improves colorectal disorders including ulcerative colitis (UC). However, it is not established whether systemically administered butyrate benefits such patients. The current study aimed at exploring and comparing the potential of intraperitoneally, intrarectally, and orally administered butyrate against acetic acid (AA)-induced UC in rats. Intrarectal administration of 2 ml of 50% AA was done after or without prior treatment of rats for 7 consecutive days with 100 mg/kg sodium butyrate (SB) intraperitoneally, intrarectally, or orally. Rats were sacrificed after 48 h of AA-treatment. Subsequently, colon sections were processed routinely for histopathological examination. We clinically observed diarrhea, loose stools, and hemoccult-positive stools, and histologically, epithelial loss and ulceration, crypt damage, goblet cell depletion, hemorrhage, and mucosal infiltration of inflammatory cells. The changes were significantly reduced by intraperitoneal, intrarectal, or oral butyrate, with intraperitoneal butyrate exhibiting the highest potency. It is concluded that intraperitoneal administration of butyrate abrogates the lesions of AA-induced UC and its potency surpasses that of intrarectal or oral butyrate.

Mucosal healing in inflammatory bowel diseases: is there a place for nutritional supplementation?

Advanced mucosal healing (MH) after intestinal mucosal inflammation coincides with sustained clinical remission and reduced rates of hospitalization and surgical resection, explaining why MH is increasingly considered as a full therapeutic goal and as an endpoint for clinical trials. Intestinal MH is a complex phenomenon viewed as a succession of steps necessary to restore tissue structure and function. These steps include epithelial cell migration and proliferation, cell differentiation, restoration of epithelial barrier functions, and modulation of cell apoptosis. Few clinical studies have evaluated the needs for specific macronutrients and micronutrients and their effects on intestinal MH, most data having been obtained from animal and cell studies. These data suggest that supplementation with specific amino acids including arginine, glutamine, glutamate, threonine, methionine, serine, proline, and the amino acid-derived compounds, polyamines can favorably influence MH. Short-chain fatty acids, which are produced by the microbiota from undigested polysaccharides and protein-derived amino acids, also exert beneficial effects on the process of intestinal MH in experimental models. Regarding supplementation with lipids, although the effects of ω-3 and ω-6 fatty acids remain controversial, endogenous prostaglandin synthesis seems to be necessary for MH. Finally, among micronutrients, several vitamin and mineral deficiencies with different frequencies have been observed in patients with inflammatory bowel diseases and supplementation with some of them (vitamin A, vitamin D3, vitamin C, and zinc) are presumed to favor MH. Future work, including clinical studies, should evaluate the efficiency of supplementation with combination of dietary compounds as adjuvant nutritional intervention for MH of the inflamed intestinal mucosa.

Management of traveller's diarrhoea with a combination of sodium butyrate, organic acids, and A-300 silicon dioxide

Introduction

Traveller's diarrhoea (TD), defined by UNICEF/WHO as three or more unformed stools with or without other symptoms, imposes a considerable burden on travellers from developed countries. Various efforts have focused on decreasing the prevalence and severity of this condition.

Aim

To assess the efficacy of a combination of sodium butyrate, organic acids, and A-300 silicon dioxide in treatment providing symptomatic relief of TD.

Material and methods

The study was conducted in accordance with a protocol presented to the Bioethical committee of Poznan University of Medical Sciences. A total of 278 patients travelling to countries with higher risk of diarrhoea for at least 10 days were divided into a study arm being administered, in case of TD, a combination of sodium butyrate, organic acids, and A-300 silicon dioxide (n = 139) and a placebo arm (n = 139) with placebo administration.

Results

Forty-seven patients completed the study (22 in the study arm and 25 in the placebo arm). The diarrhoea occurrence after initiation of treatment at first symptoms was significantly lower in the study arm as compared to the placebo arm (9% vs. 36%, p = 0.041). Also, subjects from the study arm more frequently reported that the regimen administered had been efficient for their symptoms in comparison to the placebo arm (72.7% vs. 32%, p = 0.008). No adverse effects of the administered medication were noted during the study.

Conclusions

Sodium butyrate, organic acids, and A-300 silicon dioxide can be successful in decreasing symptoms of TD. Because of its efficacy and lack of observed side effects it has a strong potential in the treatment of patients with TD.

Cellular changes of the colon after mechanical bowel preparation

BACKGROUND

The purpose of this study was to evaluate the effect of mechanical bowel preparation (MBP) on the intracellular environment, specifically evaluating butyrate transport, within the colon of the Sprague-Dawley rat.

METHODS

Sixty-eight Sprague-Dawley rats were randomized to either an MBP group (n = 34) or a control group (n = 34). Twenty-four hours after the completion of the MBP, both groups were euthanized, and the colons were harvested. The level of cellular apoptosis was investigated after DNA fragmentation, poly(ADP-ribose) polymerase cleavage, and caspase assays. Western blot analysis was performed to measure the expression of the butyrate transporter protein, monocarboxylate transporters 1, and proliferating cell nuclear antigen (a marker for tissue proliferation). Immunohistochemical staining was performed to further investigate cellular proliferation. Statistical significance (P < 0.05) was determined using two-tailed t-test.

RESULTS

Apoptosis was detected without significant differences in both groups. Western Blot analysis demonstrated that the expression of the monocarboxylate transporters 1 protein is downregulated in the MBP group (10.18 ± 3.09) compared with the control group (16.73 ± 7.39, P = 0.001), and proliferating cell nuclear antigen levels showed a decrease in cellular proliferation in the MBP group (13.35 ± 5.88) compared with the control (20.07 ± 7.55, P = 0.018). Immunohistochemistry confirmed a decrease in cellular proliferation after MBP with 23.4 ± 7.8% of the cells staining positive for Ki-67 in the MBP group versus 28.6 ± 7.9% in the control group (P = 0.006).

CONCLUSIONS

MBP has a negative impact on cellular proliferation and intracellular transport of butyrate within the rat colon, not related to apoptosis. This is the first study to demonstrate the intracellular effects that MBP has on the rat colon.

Efficacy and Safety ofGwakhyangjeonggi-SanRetention Enema in Normal Rats and Spontaneously Hypertensive Rats

The purpose of this study is to establish a protocol of retention-enema experiments and evaluate the antihypertensive effect and the safety of Gwakhyangjeonggi-san retention enema. Normal and spontaneously hypertensive rats (SHRs) were divided into treatment and control groups, respectively. We applied the Gwakhyangjeonggi-san extract by decoction and 0.9% NaCl in each group, estimated the blood pressure and body weight, and performed HPLC analysis. ALT, AST, BUN, and creatinine were examined. The systolic blood pressure within each group in normal rats differed significantly in time effect, and so did the diastolic blood pressure in the treatment group of normal rats. The systolic, diastolic, and mean blood pressure showed significant differences in group effect in the treatment group of the SHRs. The time effect of the body weight in both groups of normal rats differed significantly, so did group × time and time effects in both groups of SHRs. AST, ALT, BUN, and creatinine showed no significant difference between groups. We concluded that the Gwakhyangjeonggi-san retention enema has a hypotensive effect in normal rats within the regular range of blood pressure, but an antihypertensive effect in SHRs. Also, the intervention is safe and does not affect the liver and kidney functions in normal rats.

Use of butyrate or glutamine in enema solution reduces inflammation and fibrosis in experimental diversion colitis

AIM: To investigate whether butyrate or glutamine enemas could diminish inflammation in experimental diversion colitis.

METHODS: Wistar specific pathogen-free rats were submitted to a Hartmann’s end colostomy and treated with enemas containing glutamine, butyrate, or saline. Enemas were administered twice a week in the excluded segment of the colon from 4 to 12 wk after the surgical procedure. Follow-up colonoscopy was performed every 4 wk for 12 wk. The effect of treatment was evaluated using video-endoscopic and histologic scores and measuring interleukin-1β, tumor necrosis factor-alpha, and transforming growth factor beta production in organ cultures by enzyme linked immunosorbent assay.

RESULTS: Colonoscopies of the diverted segment showed mucosa with hyperemia, increased number of vessels, bleeding and mucus discharge. Treatment with either glutamine or butyrate induced significant reductions in both colonoscopic (P < 0.02) and histological scores (P < 0.01) and restored the densities of collagen fibers in tissue (P = 0.015; P = 0.001), the number of goblet cells (P = 0.021; P = 0.029), and the rate of apoptosis within the epithelium (P = 0.043; P = 0.011) to normal values. The high levels of cytokines in colon explants from rats with diversion colitis significantly decreased to normal values after treatment with butyrate or glutamine.

CONCLUSION: The improvement of experimental diversion colitis following glutamine or butyrate enemas highlights the importance of specific luminal nutrients in the homeostasis of the colonic mucosa and supports their utilization for the treatment of human diversion colitis.

Resistant starch, large bowel fermentation and a broader perspective of prebiotics and probiotics

The metabolic end products of the large bowel microbiota contribute significantly to human health. After weaning to solid foods, some of the most important of these are the short chain fatty acids (SCFA) produced by the fermentation of undigested dietary components and endogenous secretions. The main SCFA are acetate, propionate and butyrate which have numerous documented effects promoting large bowel function. Of the major acids, butyrate seems especially important. It is a major metabolic fuel for colonocytes and promotes a normal phenotype in these cells, potentially lowering the risk of diseases such as colo-rectal cancer. Imbalances in the microbiota are thought to predispose to large bowel dysfunction and probiotics are being developed to correct this. However, most commercial products contain bacteria (lactobacilli and bifidobacteria) which are dominant species in milk-fed infants but have limited roles in adults. Prebiosis is defined usually by the specific stimulation of these bacteria. However, the end products of most probiotics do not include butyrate or propionate which raises questions about their effectiveness in promoting bowel health in adults. Resistant starch (RS) is a dietary fibre component and its fermentation generally favours butyrate production. Dietary RS intakes and faecal butyrate levels are high in populations at low risk of diet-related large bowel diseases. Conversely, RS intakes and faecal butyrate levels are very low in high risk groups. This raises the possibility that greater RS consumption could be of health benefit. RS is not regarded widely as a prebiotic but (according to the accepted definition) most forms show the requisite features in stimulating specific bacteria, giving raised total SCFA and butyrate levels and a consequent benefit to the host. Current efforts to improve public health through increasing RS consumption could be facilitated by greater recognition of its prebiotic role.

Collagen fleeces do not improve colonic anastomotic strength but increase bowel obstructions in an experimental rat model

PURPOSE

To investigate whether a collagen fleece kept in place by fibrin glue might seal off a colorectal anastomosis, provide reinforcement, and subsequently improve anastomotic healing.

METHODS

Wistar rats underwent a 1-cm left-sided colonic resection followed by a 4-suture end-to-end anastomosis. They were then randomly assigned to one of three treatment groups: no additional intervention (control, n = 20), the anastomosis covered with fibrin glue (fibrin glue, n = 20), the anastomosis covered with a collagen fleece, kept in place with fibrin glue (collagen fleece, n = 21). At either 3 or 7 days follow-up, anastomotic bursting pressure was measured and tissue was obtained for histology and collagen content assessment after which animals were sacrificed.

RESULTS

Three rats in the control (15%), three in the fibrin glue (15%), and one in the collagen group (4.8%) died due to anastomotic complications (P = 0.497). Anastomotic bursting pressures were not significantly different between groups at 3 and 7 days follow-up (P = 0.659 and P = 0.427, respectively). However, bowel obstructions occurred significantly more often in the collagen group compared to the control group (14/21 vs. 3/20, P = 0.003). Collagen contents were not different between groups, but histology showed a more severe inflammation in the collagen group compared to the other groups at both 3 and 7 days follow-up.

CONCLUSIONS

A collagen fleece kept in place by fibrin glue does not improve healing of colonic anastomoses in rats. Moreover, this technique induces significantly more bowel obstructions in rats, warranting further study before being translated to a clinical setting.