High occurrence of small intestinal bacterial overgrowth in primary biliary cholangitis

Epidemiology of small intestinal bacterial overgrowth

Small intestinal bacterial overgrowth (SIBO) is defined as an increase in the bacterial content of the small intestine above normal values. The presence of SIBO is detected in 33.8% of patients with gastroenterological complaints who underwent a breath test, and is significantly associated with smoking, bloating, abdominal pain, and anemia. Proton pump inhibitor therapy is a significant risk factor for SIBO. The risk of SIBO increases with age and does not depend on gender or race. SIBO complicates the course of a number of diseases and may be of pathogenetic significance in the development of their symptoms. SIBO is significantly associated with functional dyspepsia, irritable bowel syndrome, functional abdominal bloating, functional constipation, functional diarrhea, short bowel syndrome, chronic intestinal pseudo-obstruction, lactase deficiency, diverticular and celiac diseases, ulcerative colitis, Crohn’s disease, cirrhosis, metabolic-associated fatty liver disease (MAFLD), primary biliary cholangitis, gastroparesis, pancreatitis, cystic fibrosis, gallstone disease, diabetes, hypothyroidism, hyperlipidemia, acromegaly, multiple sclerosis, autism, Parkinson’s disease, systemic sclerosis, spondylarthropathy, fibromyalgia, asthma, heart failure, and other diseases. The development of SIBO is often associated with a slowdown in orocecal transit time that decreases the normal clearance of bacteria from the small intestine. The slowdown of this transit may be due to motor dysfunction of the intestine in diseases of the gut, autonomic diabetic polyneuropathy, and portal hypertension, or a decrease in the motor-stimulating influence of thyroid hormones. In a number of diseases, including cirrhosis, MAFLD, diabetes, and pancreatitis, an association was found between disease severity and the presence of SIBO. Further work on the effect of SIBO eradication on the condition and prognosis of patients with various diseases is required.

Disease burden of primary biliary cholangitis and associated pruritus based on a cross-sectional US claims analysis

Objective

In order to identify areas of unmet need in patients with primary biliary cholangitis (PBC), this study sought to use real-world observational healthcare data to characterise the burden in patients with PBC and in PBC patients with a recorded diagnosis of pruritus.

Design

This retrospective, cross-sectional database study compared prevalence of prespecified comorbidities and medications in the PBC population and PBC-pruritus subpopulation with non-cases using an indirect standardisation approach. The PBC population was identified from the US IBM MarketScan Commercial Claims and Medicare Supplemental Database during 2016 using International Classification of Diseases 10th Revision, Clinical Modification codes (≥2 claims for PBC); the PBC-pruritus subpopulation additionally had ≥1 claim for pruritus during this period. Non-cases had no claims for PBC. Indirect age-sex standardised prevalence ratios (iSPR) and 95% confidence intervals (CIs) were calculated for prespecified comorbidities and medications recorded during 2017.

Results

The PBC population (N=1963) and PBC-pruritus subpopulation (N=139) had significantly higher prevalence of fatigue (19.9%, iSPR (95% CI): 1.51 (1.36 to 1.66); 26.6%, 2.10 (1.48 to 2.90)), depression/anxiety (21.3%, 1.09 (0.99 to 1.20); 28.1%, 1.46 (1.04 to 2.00)) and sleep-related issues (6.9%, 1.18 (0.99 to 1.40); 14.4%, 2.58 (1.58 to 3.99)) compared with non-cases. Bile acid sequestrants were prescribed in 5.8% and 18.0% of the PBC and PBC-pruritus populations, respectively. In general, a higher prevalence of comorbidities and medication use was observed in the PBC-pruritus subpopulation compared with the PBC population and non-cases.

Conclusion

Despite availability of treatments for PBC, the PBC population had a higher burden of comorbidities than non-cases. This burden was even greater among the PBC-pruritus subpopulation, with a particularly high prevalence of sleep disorders and depression/anxiety. Despite this, pruritus remains undertreated highlighting a need for treatments specifically indicated for cholestatic pruritus.

Intestinal homeostasis in autoimmune liver diseases

ABSTRACT

Intestinal homeostasis depends on complex interactions between the gut microbiota and host immune system. Emerging evidence indicates that the intestinal microbiota is a key player in autoimmune liver disease (AILD). Autoimmune hepatitis, primary biliary cholangitis, primary sclerosing cholangitis, and IgG4-related sclerosing cholangitis have been linked to gut dysbiosis. Diverse mechanisms contribute to disturbances in intestinal homeostasis in AILD. Bacterial translocation and molecular mimicry can lead to hepatic inflammation and immune activation. Additionally, the gut and liver are continuously exposed to microbial metabolic products, mediating variable effects on liver immune pathologies. Importantly, microbiota-specific or associated immune responses, either hepatic or systemic, are abnormal in AILD. Comprehensive knowledge about host-microbiota interactions, included but not limited to this review, facilitates novel clinical practice from a microbiome-based perspective. However, many challenges and controversies remain in the microbiota field of AILD, and there is an urgent need for future investigations.

Primary Biliary Cholangitis and Primary Sclerosing Cholangitis: Current Knowledge of Pathogenesis and Therapeutics

Cholangiopathies encompass various biliary diseases affecting the biliary epithelium, resulting in cholestasis, inflammation, fibrosis, and ultimately liver cirrhosis. Primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) are the most important progressive cholangiopathies in adults. Much research has broadened the scope of disease biology to genetic risk, epigenetic changes, dysregulated mucosal immunity, altered biliary epithelial cell function, and dysbiosis, all of which interact and arise in the context of ill-defined environmental triggers. An in-depth understanding of the molecular pathogenesis of these cholestatic diseases will help clinicians better prevent and treat diseases. In this review, we focus on the main underlying mechanisms of disease initiation and progression, and novel targeted therapeutics beyond currently approved treatments.

The Gut-Liver Axis in Cholestatic Liver Diseases

The gut-liver axis describes the physiological interplay between the gut and the liver and has important implications for the maintenance of health. Disruptions of this equilibrium are an important factor in the evolution and progression of many liver diseases. The composition of the gut microbiome, the gut barrier, bacterial translocation, and bile acid metabolism are the key features of this cycle. Chronic cholestatic liver diseases include primary sclerosing cholangitis, the generic term secondary sclerosing cholangitis implying the disease secondary sclerosing cholangitis in critically ill patients and primary biliary cirrhosis. Pathophysiology of these diseases is not fully understood but seems to be multifactorial. Knowledge about the alterations of the gut-liver axis influencing the pathogenesis and the outcome of these diseases has considerably increased. Therefore, this review aims to describe the function of the healthy gut-liver axis and to sum up the pathological changes in these cholestatic liver diseases. The review compromises the actual level of knowledge about the gut microbiome (including the mycobiome and the virome), the gut barrier and the consequences of increased gut permeability, the effects of bacterial translocation, and the influence of bile acid composition and pool size in chronic cholestatic liver diseases. Furthermore, therapeutic implications and future scientific objectives are outlined.

Predictors of Small Intestinal Bacterial Overgrowth in Symptomatic Patients Referred for Breath Testing

Background

Indications for a breath test (BT) are well established in the symptomatic patient with risk factors predisposing them to small intestinal bacterial overgrowth (SIBO). Characteristics and the profile of this population are not well known. Our objective was to study the characteristics of patients undergoing a BT for SIBO and to identify factors associated with a positive BT.

Methods

Retrospective study was conducted from 2012 to 2016 at the neurogastroenterology unit of the Centre Hospitalier de l'Universite de Montreal (CHUM). All patients who completed a BT (lactulose and/or glucose) were included. Demographics and clinical factors were analyzed to identify predictors of positive BT. Type of antibiotic treatment and clinical response were compiled. Groups of patients with (SIBO⁺) and without SIBO (SIBO^-) were also compared.

Results

A total of 136 patients were included in the study (mean age 51.2, range 20 - 80 years; 63% women), and SIBO was detected in 33.8% (n = 46). Both groups were similar in terms of age, body mass index, and gender. SIBO was significantly associated with the presence of abdominal pain (odds ratio (OR) = 4.78; P < 0.05), bloating (OR = 5.39; P < 0.05), smoking (OR = 6.66; P < 0.05), and anemia (OR = 4.08; P < 0.05). No association was identified with gender, age, obesity, and risk factors for SIBO. Antibiotics were used in 43% of patients with a positive BT, but clinical response was not significantly different in the subgroup that received antibiotics versus the subgroup that did not.

Conclusions

The prevalence of SIBO is high in symptomatic patients who underwent breath testing. Abdominal pain, bloating, smoking, and anemia are strongly associated with SIBO. Treatment of SIBO with antibiotics needs to be further investigated to better determine its efficacy on gastrointestinal symptoms.

Maldigestion Versus Malabsorption in the Elderly

PURPOSE OF REVIEW

To evaluate recently published information about the frequency of maldigestion and malabsorption in older individuals, likely diagnoses causing these problems, and the diagnostic scheme when these diagnoses are being considered.

RECENT FINDINGS

Although the prevalence of malnourishment and frank malnutrition may be increasing among older adults admitted to the hospital, this appears to be due to reduced food intake rather than maldigestion or malabsorption. The mechanisms of food digestion and absorption seem to be resilient, even in old age, but concurrent illness may produce malabsorption in older individuals. Illnesses that may be more common among the elderly include small intestinal bacterial overgrowth, exocrine pancreatic insufficiency, enteropathies, vascular disease, diabetes, and certain infections, such as Whipple's disease. In addition, older adults may have had previous surgeries or exposure to medicines which may induce malabsorption. The presentation of maldigestion and malabsorption in the elderly may be different than in younger individuals, and this may contribute to delayed recognition, diagnosis, and treatment. Diagnostic testing for maldigestion and malabsorption generally is similar to that used in younger patients. Maldigestion and malabsorption occur in older individuals and require a high level of suspicion, especially when weight loss, sarcopenia, or nutrient deficiencies are present.

Gut-Liver Axis and Inflammasome Activation in Cholangiocyte Pathophysiology

The Nlrp3 inflammasome is a multiprotein complex activated by a number of bacterial products or danger signals and is involved in the regulation of inflammatory processes through caspase-1 activation. The Nlrp3 is expressed in immune cells but also in hepatocytes and cholangiocytes, where it appears to be involved in regulation of biliary damage, epithelial barrier integrity and development of fibrosis. Activation of the pathways of innate immunity is crucial in the pathophysiology of hepatobiliary diseases, given the strong link between the gut and the liver. The liver secretes bile acids, which influence the bacterial composition of the gut microbiota and, in turn, are heavily modified by microbial metabolism. Alterations of this balance, as for the development of dysbiosis, may deeply influence the composition of the bacterial products that reach the liver and are able to activate a number of intracellular pathways. This alteration may be particularly important in the pathogenesis of cholangiopathies and, in particular, of primary sclerosing cholangitis, given its strong association with inflammatory bowel disease. In the present review, we summarize current knowledge on the gut–liver axis in cholangiopathies and discuss the role of Nlrp3 inflammasome activation in cholestatic conditions.