New insights into bile acid malabsorption

Screening of the Lipid-Lowering Probiotic Lactiplantibacillus Plantarum SDJ09 and its Anti-Obesity Mechanism

In this study, 39 strains of lactic acid bacteria were screened from several fermented foods. Based on the evaluation of functional and prebiotic properties, Lactiplantibacillus plantarum SDJ09 was selected as a promising candidate. It gave a 48.16% cholesterol reduction and 33.73% pancreatic lipase inhibition in cells; exhibited high resistance to acid, bile salts, and gastrointestinal fluid; and had strong antibacterial activity and high adhesion capabilities. More importantly, the lipid-lowering effect of L. plantarum SDJ09 was also investigated using 3T3-L1 mature adipocytes and HepG2 nonalcoholic fatty liver disease models. L. plantarum SDJ09 effectively decreased triglyceride accumulation by more than 50% in both cell models, in which the expression of PPARγ, C/EBPα, aP2, and LPL in 3T3-L1 cells was significantly downregulated by L. plantarum SDJ09. L. plantarum SDJ09 also improved lipid metabolism by downregulating the expression of HMGCR, SREBP-1c, ACC, and FAS and upregulating the expression of CYP7A1 in HepG2 nonalcoholic steatohepatitis cells. Therefore, L. plantarum SDJ09 has the potential to effectively decrease obesity and non-alcoholic fatty liver disease (NAFLD) by inhibiting lipid accumulation, providing a prospective probiotic agent for anti-obesity.

The effect of ileal resection length on postoperative complications and prognosis in right colon cancer

BACKGROUND

There is a lack of literature on the length of the terminal ileum to be resected in right hemicolectomy for colon cancer. Therefore, we aimed to determine the mean ileal loop length and the effect of this variation on postoperative complications and long-term oncological outcomes in patients who underwent right hemicolectomy.

METHODS

Right hemicolectomy surgeries performed for colon cancer in a tertiary care hospital between January 2011 and December 2018 were retrospectively analyzed from a prospective database. Two patient groups were established based on the mean length of the resected ileum above and below 7 cm. The two groups were compared for clinicopathological data, postoperative complications, mortality, long-term overall survival (OS) and disease-free survival (DFS). The factors contributing to OS and DFS were analyzed.

RESULTS

The study included 217 patients. Body mass index (BMI) values were significantly higher in the ileum resection length > 7 cm group (p = 0.009). Pathological N stage, tumor diameter, and number of metastatic lymph nodes were significantly higher in the ileum resection length > 7 cm group (p = 0.001, p = 0.001, and p = 0.026, respectively). There was no significant difference for postoperative complication and mortality rates between the two groups. The mean follow-up period was 61.2 months (2-120) in all patients. The total number of deaths was 29 (11.7%) while the 60-month OS was 83.5% and 50-month DFS was 81.8%. There was no significant difference between the groups in terms of OS and DFS rates (p > 0.05).

CONCLUSIONS

Excessive resection of the distal ileum in right hemicolectomy does not provide any benefit in terms of prognosis and complications.The ileum resection length and values close to it in our study appear to be sufficient.

Microbiota-mediated metabolic perturbations in the gut and brain of mice after microplastic exposure

Microplastics (MPs), emerging environmental toxicants, have drawn attention because of their wide distribution in the environment. Exposure to MPs induces gut microbiota dysbiosis, intestinal barrier dysfunction, metabolic perturbations, and neurotoxicity in different rodents. However, the relationship between MPs, gut microbiota, and the metabolome of the gut and brain in mice remains unclear. In this study, female C57BL/6 mice were orally gavaged with vehicle, 200 nm MP, and 800 nm MP three times per week for four weeks. Cecal contents were collected for gut microbiota analysis using 16S rRNA gene sequencing. Intestinal and brain tissues from mice were used to determine metabolic profiles using liquid chromatography-mass spectrometry (LC-MS). The results showed that MP altered microbiota composition, accompanied by metabolic perturbations in the mouse gut and brain. Specifically, Firmicutes and Bacteroidetes were suggested to be important phyla for MP exposure, partially dominating further metabolite alterations. Simultaneously, MP-induced metabolic profiles were associated with energy homeostasis and bile acid, nucleotide, and carnitine metabolic pathways. The results of the mediation analysis further revealed an MP-microbiota-metabolite relationship. Our results indicate that MPs can induce gut dysbiosis and disturb metabolic dysfunction in the mouse brain and/or intestine. Integrative omics approaches have the potential to monitor MP-induced molecular responses in various organs and systematically elucidate the complex mechanisms of human health effects.

Bile Acids and Short-Chain Fatty Acids Are Modulated after Onion and Apple Consumption in Obese Zucker Rats

Gut microorganisms are involved in the development and severity of different cardiovascular diseases, and increasing evidence has indicated that dietary fibre and polyphenols can interact with the intestinal microbiota. The study objective was to investigate the effect of onion and apple intake on the major types of microbial-derived molecules, such as short-chain fatty acids (SCFAs) and bile acids (BAs). Obese Zucker rats were randomly assigned (n = eight rats/group) to a standard diet (OC), a standard diet/10% onion (OO), or a standard diet/10% apple (OA). Lean Zucker rats fed a standard diet served as a lean control (LC) group. Faecal samples were collected at baseline, and 8 weeks later, the composition of the microbial community was measured, and BA and SCFA levels were determined using high-performance liquid chromatography-mass spectrometry (HPLC-MS) and gas chromatography-mass spectrometry (GC-MS), respectively. Rats fed onion- and apple-enriched diets had increased abundance of beneficial bacteria, such as Bifidobacterium spp. and Lactobacillus spp., enhanced SCFAs (acetic, propionic, isobutyric, and valeric acids), decreased excretion of some BAs, mainly of the primary (CA, α-MCA, and β-MCA) and secondary type (ω-MCA, HDCA, NCA, DCA, and LCA), and increased amount of taurine- and glycine-conjugated BAs compared to the OC group. The contribution of specific bioactive compounds and their metabolites in the regulation of the microbiome and the pathways linked to SCFA and BA formation and their relationship with some diseases needs further research.

Biomarkers for Bile Acid Malabsorption in Diarrhea-predominant Irritable Bowel Syndrome: A Systematic Review and Meta-analysis

BACKGROUND AND AIM

A clear relationship of biological indexes between bile acid malabsorption (BAM) and diarrhea-predominant irritable bowel syndrome (IBS-D) has not been well analyzed. This meta-analysis aimed to establish a more convenient method to diagnose BAM in IBS-D patients by comparing the differences in biomarkers between IBS-D patients and healthy people.

METHODS

Multiple databases were searched for relevant case-control studies. Indicators used to diagnose BAM included 75Se-homocholic acid taurine (SeHCAT), 7α-hydroxy-4-cholesten-3-one(C4), fibroblast growth factor-19 and 48-hour fecal bile acid (48FBA). The rate of BAM (SeHCAT) was calculated by using a random-effect model. The levels of C4, FGF19, and 48FBA were compared, and the overall effect size was combined by a fixed effect model.

RESULTS

The search strategy identified 10 relevant studies comprising 1034 IBS-D patients and 232 healthy volunteers. The pooled rate of BAM in IBS-D patients was 32% (according to SeHCAT; 95% CI: 24%-40%). The level of C4 in IBS-D patients was significantly higher than that in the control group (2.86 ng/mL; 95% CI: 1.09, 4.63); The level of FGF19 was significantly lower than that in the control group (-33.97 pg/mL; 95% CI: -51.13, -16.82); The level of 48FBA was significantly higher than that in the control group (0.059; 95% CI: 0.41, 0.77).

CONCLUSIONS

The results mainly concluded serum C4 and FGF19 levels in IBS-D patients. Most of the studies have different normal cutoff points of serum C4 and FGF19 levels; the performance of each test should be further estimated. By comparing the levels of these biomarkers, BAM in patients with IBS-D could be identified more accurately, which would lead to more effective treatment.

Farnesoid X Receptor (FXR) Regulates mTORC1 Signaling and Autophagy by Inhibiting SESN2 Expression

SCOPE

The mechanistic target of rapamycin complex 1 (mTORC1), as a link between nutrients and autophagy, senses many nutrients in the microenvironment. A growing body of recent literature describes the function of bile acids (BAs) as versatile signaling molecules, while it remains largely unclear whether mTORC1 can sense BAs and the mechanism has not been studied.

METHODS AND RESULTS

After treating LO2 cells with indicated concentration of chenodeoxycholic acid (CDCA) and farnesoid X receptor (FXR) inhibitor/activator for 6 h, it finds that CDCA and FXR significantly accelerate mTORC1 activation. The results of immunofluorescence indicate that CDCA and FXR inhibit cellular autophagy through activating mTORC1 pathway. In particular, these findings show that CDCA and FXR promote the lysosomal translocation and activation of mTORC1 in an amino acid-sensitive manner. Mechanistically, the transcriptomics data indicate that SESN2 is a checkpoint for mTORC1 lysosome translocation and activation induced by FXR, and knockdown SESN2 with siRNA suppresses the regulation of FXR on autophagy.

CONCLUSION

These results indicate that FXR-induced decrease in SESN2 expression and activation of the mTORC1 pathway can control autophagy and be explored as potential therapeutic targets for enterohepatic and metabolic disorders.

Variation in the length of terminal ileum specimen in right hemicolectomy: a descriptive study

AIM

The aim of this study was to clarify the length of the bowel specimen and to assess if the length was affected by certain characteristics.

METHODS

Eligible patients were adults who had undergone right hemicolectomy for cancer in caecum, appendix, ascending colon or transverse colon from September 2019 to September 2020 at Herlev Hospital, Denmark. Data were collected from medical records. The primary outcome was the length of the resected terminal ileum. Secondary outcomes were to assess if body mass index (BMI), surgical approach, and neoadjuvant chemotherapy affected the length of the terminal ileum specimen, and to report the length of the colon specimen subdivided on the cancer locations.

RESULTS

In total, 50 patients were included. The median age was 74 years (range 36-91), 30 patients (60%) were females, and BMI was median 26 (range 17-45). The variation in the length of terminal ileum specimen was median 5 cm (range 1-17). The explorative analyses showed significant positive correlation between the length of terminal ileum specimen and BMI (P = 0.050) but not surgical approach (P = 0.23) nor neoadjuvant chemotherapy (P = 0.51). The length of the colon specimen naturally differed according to the cancer location with a median length of 26 cm (range 14-90).

CONCLUSION

We found a variation in the length of the terminal ileum specimen without an apparent explanation for this variation. The colon specimen also varied naturally according to cancer location.

Pathophysiology and Clinical Management of Bile Acid Diarrhea

Bile acid malabsorption (BAM) represents a common cause of chronic diarrhea whose prevalence is under-investigated. We reviewed the evidence available regarding the pathophysiology and clinical management of bile acid diarrhea (BAD). BAD results from dysregulation of the enterohepatic recirculation of bile acids. It has been estimated that 25–33% of patients with functional diarrhea and irritable bowel syndrome with diarrhea have BAM. Currently, the selenium homotaurocholic acid test is the gold standard for BAD diagnosis and severity assessment. However, it is an expensive method and not widely available. The validation of the utility in the clinical practice of several other serum markers, such as 7α-hydroxy-4-cholesten-3-one (C4) and the fibroblast growth factor 19 (FGF19) is ongoing. The first-line treatment of patients with BAD is bile acid sequestrants. Patients that are refractory to first-line therapy should undergo further diagnostics to confirm the diagnosis and to treat the underlying cause of BAD. An early and correct diagnosis of BAD would improve patient’s quality of life, avoiding additional diagnostic tests that burden health care systems. Considering the limited availability and tolerability of specific medications for BAD treatment, future research is awaited to identify other therapeutic approaches, such as gut microbiota modulating therapies.

Bile Acid Sequestrants for Hypercholesterolemia Treatment Using Sustainable Biopolymers: Recent Advances and Future Perspectives

Bile acids, the endogenous steroid nucleus containing signaling molecules, are responsible for the regulation of multiple metabolic processes, including lipoprotein and glucose metabolism to maintain homeostasis. Within our body, they are directly produced from their immediate precursors, cholesterol C (low-density lipoprotein C, LDL-C), through the enzymatic catabolic process mediated by 7-α-hydroxylase (CYP7A1). Bile acid sequestrants (BASs) or amphiphilic resins that are nonabsorbable to the human body (being complex high molecular weight polymers/electrolytes) are one of the classes of drugs used to treat hypercholesterolemia (a high plasma cholesterol level) or dyslipidemia (lipid abnormalities in the body); thus, they have been used clinically for more than 50 years with strong safety profiles as demonstrated by the Lipid Research Council-Cardiovascular Primary Prevention Trial (LRC-CPPT). They reduce plasma LDL-C and can slightly increase high-density lipoprotein C (HDL-C) levels, whereas many of the recent clinical studies have demonstrated that they can reduce glucose levels in patients with type 2 diabetes mellitus (T2DM). However, due to higher daily dosage requirements, lower efficacy in LDL-C reduction, and concomitant drug malabsorption, research to develop an "ideal" BAS from sustainable or natural sources with better LDL-C lowering efficacy and glucose regulations and lower side effects is being pursued. This Review discusses some recent developments and their corresponding efficacies as bile removal or LDL-C reduction of natural biopolymer (polysaccharide)-based compounds.

Bile Acid Malabsorption as a Consequence of Cancer Treatment: Prevalence and Management in the National Leading Centre

The aim was to establish prevalence of bile acid malabsorption (BAM) and management in patients who underwent treatment for malignancy. Retrospective evaluation of data in patients seen within six months (August 2019-January 2020) was carried out. Demographic, nuclear medicine (Selenium Homocholic Acid Taurine (SeHCAT) scan result), clinical (previous malignancy, type of intervention (medication, diet), response to intervention) and laboratory (vitamin D, vitamin B12 serum levels) data were searched. In total, 265 consecutive patients were reviewed. Out of those, 87/265 (33%) patients (57 females, 66%) were diagnosed with BAM. Mean age was 59 +/- 12 years. The largest group were females with gynaecological cancer (35), followed by haematology group (15), colorectal/anal (13), prostate (9), upper gastrointestinal cancer (6), another previous malignancy (9). Severe BAM was most common in haematology (10/15; 67%) and gynaecological group (21/35; 60%). Medication and low-fat diet were commenced in 65/87 (75%), medication in 10/87 (11%), diet in 6/87 (7%). Colesevelam was used in 71/75 (95%). Symptoms improved in 74/87 (85%) patients. Vitamin D insufficiency/deficiency was diagnosed in 62/87 (71%), vitamin B12 deficiency in 39/87 (45%). BAM is a common condition in this cohort however treatments are highly effective.

SLC10A2 deficiency-induced congenital chronic bile acid diarrhea and stunting

Background

Diarrhea is a common occurrence in children below the age of 5 years. In chronic cases, it induces malnutrition that severely stunts growth. Bile acid diarrhea (BAD), caused by malabsorption of bile acid (BA), is a rare form of chronic diarrhea seldom observed in pediatric patients. Here, we present a clinical report on a novel case of chronic BAD, with severe stunting in an infant, induced by a homozygous mutation of SLC10A2.

Methods

We performed DNA extraction, whole‐exome sequencing analysis, and mutation analysis of SLC10A2 to obtain genetic data on the patient. We subsequently analyzed the patient's clinical and genetic data.

Results

The patient's clinical manifestations were chronic diarrhea with increased BAs in the feces and extreme stunting, which was diagnosed as BAD. A homozygous mutation of SLC10A2 at the c.313T>C (rs201206937) site was detected.

Conclusion

Our report reveals the youngest case illustrating the characteristics of BAD induced by genetic variant at 313T>C, and the second case entailing a clear association between a SLC10A2 genetic mutation and the onset of BAD. Our findings expand the mutant spectrum of the SLC10A2 gene and contribute to the refinement of the genotype–phenotype mapping of severe stunting induced by pediatric BAD. Moreover, they highlight the value of molecular genetic screening for diagnosing BAD in young patients.

Physiology and Physical Chemistry of Bile Acids

Bile acids (BAs) are facial amphiphiles synthesized in the body of all vertebrates. They undergo the enterohepatic circulation: they are produced in the liver, stored in the gallbladder, released in the intestine, taken into the bloodstream and lastly re-absorbed in the liver. During this pathway, BAs are modified in their molecular structure by the action of enzymes and bacteria. Such transformations allow them to acquire the chemical-physical properties needed for fulling several activities including metabolic regulation, antimicrobial functions and solubilization of lipids in digestion. The versatility of BAs in the physiological functions has inspired their use in many bio-applications, making them important tools for active molecule delivery, metabolic disease treatments and emulsification processes in food and drug industries. Moreover, moving over the borders of the biological field, BAs have been largely investigated as building blocks for the construction of supramolecular aggregates having peculiar structural, mechanical, chemical and optical properties. The review starts with a biological analysis of the BAs functions before progressively switching to a general overview of BAs in pharmacology and medicine applications. Lastly the focus moves to the BAs use in material science.

Systematic review: the effect of right hemicolectomy for cancer on postoperative bowel function

BACKGROUND

Right-sided cancer accounts for approximately 30% of bowel cancer in women and 22% in men. Colonic resection can cause changes in bowel function which affect daily activity. The aims are to assess the impact of right hemicolectomy for cancer on bowel function and to identify useful treatment modalities for managing bowel dysfunction after right hemicolectomy.

METHOD

The review was conducted in line with PRISMA. Eligible studies evaluated the impact of right hemicolectomy on bowel function in those treated for colorectal neoplasia or assessed the effect of surgical technique or other intervention on bowel function after right hemicolectomy. Right hemicolectomy for inflammatory bowel disease or benign cases only were excluded. Articles were limited to studies on human subjects written in English published between January 2008 and December 2018.

RESULTS

The searches identified 7531 articles. Nine articles met the inclusion criteria, of which eight were cohort studies and one was a randomised trial. Loose stool, increased bowel frequency and/or nocturnal defaecation following right-sided colectomy occurs in approximately one in five patients. Some of these symptoms may improve spontaneously with time. Bile acid malabsorption and/or small bowel bacterial overgrowth may be the cause for chronic dysfunction. Some studies report that no or little difference in outcome between right-sided and rectal resections likely suggests poor function after right-sided resection.

CONCLUSION

Right hemicolectomy can result in changes to bowel function. Patients should be counselled preoperatively, and follow-up should be designed to identify and effectively treat significantly altered bowel function.

Block copolymers as bile salt sequestrants: intriguing structures formed in a mixture of an oppositely charged amphiphilic block copolymer and bile salt

To study the formation and characterize the structure of mixed complexes of oppositely charged block copolymers and surfactants are of great significance for practical applications, e.g., in drug carrier formulations that are based on electrostatically assisted assembly. In this context, biocompatible block copolymers and biosurfactants (like bile salts) are particularly interesting. In this work, we report on the co-assembly in dilute aqueous solution between a cationic poly(N-isopropyl acryl amide) (PNIPAM) diblock copolymer and the oppositely charged bile salt surfactant sodium deoxycholate at ambient temperature. The cryogenic transmission electron microscopy (cryo-TEM) experiments revealed the co-existence of two types of co-assembled complexes of radically different morphology and inner structure. They are formed mainly as a result of the electrostatic attraction between the positively charged copolymer blocks and bile salt anions and highlight the potential of using linear amphiphilic block copolymers as bile salt sequestrants in the treatment of bile acid malabsorption and hypercholesterolemia. The first complex of globular morphology has a coacervate core of deoxycholate anions and charged copolymer blocks surrounded by a PNIPAM corona. The second complex has an intriguing tape-like supramolecular morphology of several micrometer in length that is striped in the direction of the long axis. A model is presented in which the stretched cationic blocks of several block copolymers interact electrostatically with the bile salt molecules that are associated to form a zipper-like structure. The tape is covered on both sides by the PNIPAM chains that stabilize the overall complex in solution. In addition to cryo-TEM, the mixed system was investigated in a range of molar charge fractions at a constant copolymer concentration by static light scattering, small angle X-ray scattering, and electrophoretic mobility measurements.

Strain-Specific Quantification of Native Probiotic Bacillus spp. and Their Effect on Liver Function and Gut Microflora of Experimental Rats

Safety and efficacy was investigated for two candidate probiotic B. flexus MCC2427 and B. licheniformis MCC2512 via in vivo studies on albino Wistar rats. In acute toxicity assay, rats were fed with single dose of 10¹⁰ cfu mL^-1 of probiotics. The follow-up studies for next 14 days did not reveal any toxicity-related criteria indicating the non-toxicity nature of probiotics. In 90-day repeated dosage studies, the cultures were administered in three doses (10⁶, 10⁷, 10⁸ cfu mL^-1). Results showed no overt toxic effect and no drastic treatment-related changes pertaining to histopathology of vital organs. DNA fingerprinting indicated the lack of bacterial translocation. Superoxide dismutase and catalase activity indicated their antioxidant potential. Reduced serum cholesterol with improved HDL-cholesterol specified the cholesterol-reducing ability of the cultures, which was also apparent with increased excretion of cholic acid in feces. Both probiotic cultures positively altered the gut microbial environment, retained lactic acid bacterial effect, and simultaneously reduced pathogenic strains. A sensitive and rapid tool was developed using strain-specific qPCR primers, which facilitated appropriate estimation of test culture in feces. The data strongly advocate the safety of tested probiotics at levels used in the study.

Irritable Bowel Syndrome: Pathophysiology and Current Therapeutic Approaches

Irritable bowel syndrome (IBS) is a prevalent condition affecting 10-20% of adults in most countries; IBS results in significant morbidity and health care costs. IBS is a disorder of the brain-gut axis, and recent insights into the pathophysiological mechanisms include altered bile acid metabolism, neurohormonal regulation, immune dysfunction, alterations in the epithelial barrier, and secretory properties of the gut. There remains a significant unmet need for effective treatments, particularly for the pain component of IBS, although the introduction of drugs directed at secretion, motility, and a nonabsorbable antibiotic provides an option for the bowel dysfunction in IBS.

Measurement of serum 7α-hydroxy-4-cholesten-3-one as a marker of bile acid malabsorption in dogs with chronic diarrhoea: a pilot study

Bile acid malabsorption is a common cause of chronic diarrhoea in people, however it has never previously been investigated in dogs, despite clinical suspicion of its existence. The goal of this study was to assess the feasibility of measuring serum 7α-hydroxy-4-cholesten-3-one (C4) in dogs, as a potential marker of bile acid malabsorption, and to see whether this is related to clinical disease severity or the presence of hypocobalaminaemia. Serum C4 concentration was measured in 20 clinically healthy control dogs and 17 dogs with chronic diarrhoea. Three of the 17 affected dogs (17.6 per cent) had a C4 concentration significantly above the range of clinically healthy dogs; these dogs were all poorly responsive to conventional therapy. These results suggest that bile acid malabsorption may be a clinically relevant disorder in dogs with chronic diarrhoea and serum C4 may be a useful tool to investigate this further.

Bile acid malabsorption in inflammatory bowel disease

Bile acid malabsorption (BAM) is a common but an underestimated and often neglected sign of inflammatory bowel diseases (IBDs), especially those affecting the distal ileum. Clinically relevant BAM is most often present in patients with Crohn's ileitis and particularly in ileal-resected Crohn's disease patients. However, deterioration of bile acid (BA) metabolism occurs also in patients with IBD without ileal disease or in those in clinical remission, and the role of BAM in these patients is not well appreciated by clinicians. In a majority of cases, BAM in IBD is caused by impaired conjugated BA reabsorption, mediated by apical sodium/BA cotransporting polypeptide, localized at the luminal surface of the ileal enterocytes. As a consequence, numerous pathological sequelae may occur, including the malfunction of lipid digestion with clinical steatorrhea, impaired intestinal motility, and/or significant changes in the intestinal microflora environment. In this review, a detailed description of the pathophysiological mechanisms of BAM-related diarrhea is presented. Although BAM is present in a significant number of patients with Crohn's disease, its laboratory assessment is not routinely included in diagnostic workups, partially because of costs, logistical reasons, or the unavailability of the more sophisticated laboratory equipment needed. Simultaneously, novel findings related to the effects of the BA signaling pathways on immune functions (mediated through TGR5, cell membrane G protein-coupled BA receptor 1, nuclear farnesoid X receptor, nuclear pregnane X receptor, or nuclear vitamin D receptor) are discussed along with intestinal metabolism in its relationship to the pathogenesis of IBD.

The brain-gut axis in health and disease

The interaction between the brain and the gut has been recognized for many centuries. This bidirectional interaction occurs via neural, immunological and hormonal routes, and is important not only in normal gastrointestinal function but also plays a significant role in shaping higher cognitive function such as our feelings and our subconscious decision-making. Therefore, it remains unsurprising that perturbations in normal signalling have been associated with a multitude of disorders, including inflammatory and functional gastrointestinal disorders, and eating disorders.

Colesevelam for the treatment of bile acid malabsorption-associated diarrhea in patients with Crohn's disease: a randomized, double-blind, placebo-controlled study

BACKGROUND AND AIMS

Bile acid malabsorption (BAM)-associated diarrhea is an important clinical issue in patients with Crohn's disease (CD). We analyzed the efficacy and safety of the bile acid sequestrant colesevelam for treatment of BAM-associated diarrhea in CD patients in a randomized, double-blind, placebo-controlled study.

METHODS

The primary endpoint was the proportion of patients with >30% reduction of liquid stools/day from baseline to termination visit at week 4. Secondary endpoints were reduction of the number of liquid stools/day, improvement of stool consistency and quality of life.

RESULTS

26 patients were analyzed in the intention-to-treat (ITT) analysis. The primary endpoint was reached by 10 patients (69.7%) in the colesevelam group compared to 3 patients (27.3%) in the placebo group (risk difference RD=.394, 95%CI:[-0.012; 0.706]; P=.0566). In the per-protocol analysis (n=22), the risk difference was statistically significant (RD=.470, 95%CI:[0.018; 0.788], P(H0: RD=0)=0.0364; 95% CI:[1.3;54.7]). Regarding secondary endpoints, in the ITT population colesevelam-treated patients had a significant reduction of liquid stools/day at week 4 (median 5.0 to 2.0; P=0.01), while patients treated with placebo had no significant reduction (median 4.0 to 3.0; P=0.42). Significantly more patients in the colesevelam group had improvement of stool consistency of at least one level in the Bristol stool chart, as compared to the placebo group (P=0.003).

CONCLUSIONS

We found significant differences in favor for colesevelam treatment compared to placebo treatment for CD patients with BAM regarding the reduction of the number of liquid stools/day and stool consistency. ClinicalTrials.gov number: NCT01203254.

Elobixibat and its potential role in chronic idiopathic constipation

Chronic idiopathic constipation is highly prevalent among adults. Bile acids (BAs) and the enterohepatic BA circulation modulate colonic secretion and motility that affect transit. BAs in the colon have a dual action as osmotic and stimulant agents. Newer agents, such as elobixibat (A3309), an inhibitor of the ileal BA transporter, have the potential to improve significantly the management of chronic constipation, with minimal adverse effects. Elobixibat modulates the enterohepatic BA circulation, enhancing the delivery of BAs to the colon where they induce secretory and motor effects. Secondary effects of the inhibition of BA absorption are reduced activation of the farnesoid X receptor, decreased secretion of fibroblast growth factor-19 into the portal circulation, and increased BA synthesis. This review focuses on the role of BAs, the enterohepatic BA circulation, and an ileal BA transporter inhibitor (elobixibat) in chronic constipation.

Irritable Bowel Syndrome: Peripheral Mechanisms and Therapeutic Implications

Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder, affecting about 10 to 20% of the population in developed countries. The mechanisms underlying the symptoms of this condition are poorly understood. Considered initially as the consequence of abnormal gut motility, visceral hypersensitivity, psychosocial factors and brain-gut axis dysfunction, IBS is now acknowledged as a multifactorial disorder. Specific peripheral mechanisms are involved, including mucosal immune activation, increased intestinal permeability, entero-endocrine cell products, an excess of bile acids, gut dysbiosis. A better understanding of these mechanisms could help develop new and specific therapeutic pathways in patients suffering from IBS.

Systematic review: the management of chronic diarrhoea due to bile acid malabsorption

BACKGROUND

Bile acid malabsorption (BAM) is a common, yet under-recognised, cause of chronic diarrhoea, with limited guidance available on the appropriate management of patients with BAM.

AIM

To summarise the evidence supporting different treatments available for patients with bile acid malabsorption, noting their impact on clinical outcomes, tolerability and associated side effects.

METHODS

A literature search was conducted through PubMed, the Cochrane Database of Systematic Reviews and Scopus. Relevant articles studied patients who had been diagnosed with BAM and were clinically assessed before and after therapy.

RESULTS

A total of 30 relevant publications (1241 adult patients) were identified, which investigated the clinical response to drugs, including colestyramine, colestipol, colesevelam, aluminium hydroxide and obeticholic acid. The most commonly used diagnostic test of bile acid malabsorption was the SeHCAT test (24 studies). Colestyramine treatment was by far the most studied of these agents, and was successful in 70% of 801 patients (range: 63-100%).

CONCLUSIONS

Colestyramine and colestipol are generally effective treatments of gastrointestinal symptoms from BAM, but may be poorly tolerated and reduce the bioavailability of co-administered agents. Alternative therapies (including colesevelam and aluminium hydroxide) as well as dietary intervention may also have a role, and the promising results of the first proof-of-concept study of obeticholic acid suggest that its novel approach may have an exciting future in the treatment of this condition. Future trials should employ accurate diagnostic testing and be conducted over longer periods so that the long-term benefits and tolerability of these different approaches can be evaluated.

Acta Oncologica Lecture. Gastrointestinal consequences of cancer treatment and the wider context: a bad gut feeling

BACKGROUND

The percentage of people living with a diagnosis of cancer is rising globally. Between 20% and 25% of people treated for cancer experience a consequence of cancer which has an adverse impact on the quality of their life. Gastrointestinal (GI) symptoms are the most common of all consequences of cancer treatment and have the greatest impact on daily activity. PATHOPHYSIOLOGY OF LONG-TERM BOWEL DAMAGE AFTER PELVIC RADIOTHERAPY: Long-term damage to the bowel after radiotherapy is mediated by ischaemic changes and fibrosis. Each fraction of radiotherapy causes a series of repetitive injuries to the intestinal tissue resulting in an altered healing process, which affects the integrity of the repair and changes the architecture of the bowel wall. THE NATURE OF GI SYMPTOMS THAT DEVELOP: Patient-reported outcome measures show that diarrhoea, urgency, increased bowel frequency, tenesmus and flatulence are the five most prevalent GI symptoms with a moderate or severe impact on patients' daily lives after treatment with pelvic radiotherapy. Many patients also experience fatigue, urinary problems and have sexual concerns. SYSTEMATIC ASSESSMENT AND MANAGEMENT: The complex nature of those symptoms warrants systematic assessment and management. The use of a tested algorithm can assist in achieving this. The most common contributing factors to ongoing bowel problems after pelvic radiotherapy are small intestinal bacterial overgrowth, bile acid malabsorption, pancreatic insufficiency, rectal bleeding and its impact on bone health.

THE WIDER CONTEXT

Symptom burden, socio-psychosocial impact, memory and cognitive function, fatigue, urinary problems and sexual concerns need to be taken into account when thinking about consequences of cancer treatment.

CONCLUSION

As our understanding of consequences of cancer treatments continues to emerge and encompass a wide variety of specialties, a holistic, multifaceted and multidisciplinary approach is required to manage those consequences long-term.

Recycling rate of bile acids in the enterohepatic recirculation as a major determinant of whole body 75SeHCAT retention

Measurement of the whole body retention of orally administered (75)SeHCAT is used to investigate patients with unexplained diarrhoea. Retention values of <15 % at 7 days post-administration are taken to indicate bile acid malabsorption (BAM). Whilst idiopathic BAM is frequently diagnosed with (75)SeHCAT, functional and morphological studies of the terminal ileum rarely show any abnormality, so the disorder may be more appropriately termed bile acid diarrhoea (BAD). In addition to malabsorption, excess bile acid may reach the colon, where the events leading to diarrhoea take place, as a result firstly of increased bile acid synthesis and secondly of an increased recycling rate of bile acids. Increased recycling has been largely ignored as a cause of BAD, but, as shown in this study, can readily result in excess bile acids reaching the colon even when ileal absorption efficiency is normal (i.e. 95-97 %). There needs to be a re-evaluation of the causes of BAD in patients without a history of previous intestinal resection or evidence of ileal pathology, such as Crohn's disease.

Diet1 functions in the FGF15/19 enterohepatic signaling axis to modulate bile acid and lipid levels

We identified a mutation in the Diet1 gene in a mouse strain that is resistant to hyperlipidemia and atherosclerosis. Diet1 encodes a 236 kD protein consisting of tandem low-density lipoprotein receptor and MAM (meprin-A5-protein tyrosine phosphatase mu) domains and is expressed in the enterocytes of the small intestine. Diet1-deficient mice exhibited an elevated bile acid pool size and impaired feedback regulation of hepatic Cyp7a1, which encodes the rate-limiting enzyme in bile acid synthesis. In mouse intestine and in cultured human intestinal cells, Diet1 expression levels influenced the production of fibroblast growth factor 15/19 (FGF15/19), a hormone that signals from the intestine to liver to regulate Cyp7a1. Transgenic expression of Diet1, or adenoviral-mediated Fgf15 expression, restored normal Cyp7a1 regulation in Diet-1-deficient mice. Diet1 and FGF19 proteins exhibited overlapping subcellular localization in cultured intestinal cells. These results establish Diet1 as a control point in enterohepatic bile acid signaling and lipid homeostasis.

The effect of dietary prebiotics and probiotics on body weight, large intestine indices, and fecal bile acid profile in wild type and IL10-/- mice

Previous studies have suggested roles of probiotics and prebiotics on body weight management and intestinal function. Here, the effects of a dietary prebiotic, inulin (50 mg/g diet), and probiotic, Bfidobacterium animalis subsp. lactis (Bb12) (final dose verified at 10⁵ colony forming unit (cfu)/g diet, comparable to human consumption), were determined separately and in combination in mice using cellulose-based AIN-93G diets under conditions allowed for the growth of commensal bacteria. Continuous consumption of Bb12 and/or inulin did not affect food intake or body, liver, and spleen weights of young and adult mice. Fecal bile acid profiles were determined by nanoESI-MS/MS tandem mass spectrometry. In the presence of inulin, more bacterial deconjugation of taurine from primary bile acids was observed along with an increased cecal weight. Consumption of inulin in the absence or presence of Bb12 also increased the villus cell height in the proximal colon along with a trend of higher bile acid sulfation by intestinal cells. Feeding Bb12 alone at the physiological dose did not affect bile acid deconjugation and had little effect on other intestinal indices. Although interleukin (IL)10-null mice are susceptible to enterocolitis, they maintained the same body weight as the wild type mice under our specific pathogen-free housing condition and showed no signs of inflammation. Nevertheless, they had smaller cecum suggesting a mildly compromised intestinal development even before the disease manifestation. Our results are consistent with the notion that dietary factors such as prebiotics play important roles in the growth of intestinal microbiota and may impact on the intestinal health. In addition, fecal bile acid profiling could potentially be a non-invasive tool in monitoring the intestinal environment.

Mechanisms and prospects of food protein hydrolysates and peptide-induced hypolipidaemia

Hyperlipidaemia is an important risk factor for developing cardiovascular disease, a leading global health issue. While pharmaceutical interventions have proved efficacious in acute conditions, many hypolipidaemic drugs are known to induce adverse side effects. Due to a strong positive link between functional food components and human health, emerging research has explored the application of natural food-based strategies in disease management. One of such strategies involves the use of food proteins as precursors of peptides with a wide variety of beneficial health functions. Some plant, animal and marine-derived protein hydrolysates and peptides have shown promising hypolipidaemic properties when evaluated in vitro, in cultured mammalian cells and animal models. The products exert their functions via bile acid-binding and disruption of cholesterol micelles in the gastrointestinal tract, and by altering hepatic and adipocytic enzyme activity and gene expression of lipogenic proteins, which can modulate aberrant physiological lipid profiles. The activity of the protein hydrolysates and peptides depends on their physicochemical properties including hydrophobicity of amino acid residues but there is knowledge gap on detailed structure-function relationships and efficacy in hyperlipidaemic human subjects. Based on the prospects, commercial functional food products containing hypolipidaemic peptides have been developed for enhancement of cardiovascular health.