Mucin gene expression in bile of patients with and without gallstone disease, collected by endoscopic retrograde cholangiography

Biliary microbiota and mucin 4 impact the calcification of cholesterol gallstones

BACKGROUND

Cholesterol gallstones account for over 80% of gallstones, and the pathogenesis of gallstone formation involves genetic and environmental factors. However, data on the evolution of cholesterol gallstones with various densities are limited. This study aimed to determine the roles of microbiota and mucins on the formation of calcified cholesterol gallstones in patients with cholelithiasis.

METHODS

Paired gallbladder tissues and bile specimens were obtained from cholelithiasis patients who were categorized into the isodense group and calcified group according to the density of gallstones. The relative abundance of microbiota in gallbladder tissues was detected. Immunohistochemistry and enzyme-linked immunosorbent assay were performed to detect the expression levels of MUC1, MUC2, MUC3a, MUC3b, MUC4, MUC5ac and MUC5b in gallbladder tissues and bile. The correlation of microbiota abundance with MUC4 expression was evaluated by linear regression.

RESULTS

A total of 23 patients with gallbladder stones were included. The density of gallstones in the isodense group was significantly lower than that of the calcified group (34.20 ± 1.50 vs. 109.40 ± 3.84 HU, P < 0.0001). Compared to the isodense group, the calcified group showed a higher abundance of gram-positive bacteria at the fundus, in the body and neck of gallbladder tissues. The concentrations of MUC1, MUC2, MUC3a, MUC3b, MUC5ac and MUC5b in the epithelial cells of gallbladder tissues showed no difference between the two groups, while the concentrations of MUC4 were significantly higher in the calcified group than that in the isodense group at the fundus (15.49 ± 0.69 vs. 10.23 ± 0.54 ng/mL, P < 0.05), in the body (14.54 ± 0.94 vs. 11.87 ± 0.85 ng/mL, P < 0.05) as well as in the neck (14.77 ± 1.04 vs. 10.85 ± 0.72 ng/mL, P < 0.05) of gallbladder tissues. Moreover, the abundance of bacteria was positively correlated with the expression of MUC4 (r = 0.569, P < 0.05) in the calcified group.

CONCLUSIONS

This study showed the potential clinical relevance among biliary microbiota, mucins and calcified gallstones in patients with gallstones. Gram-positive microbiota and MUC4 may be positively associated with the calcification of cholesterol gallstones.

Serum mucin 3A as a potential biomarker for extrahepatic cholangiocarcinoma

BACKGROUND/AIMS

The aim of this study is to evaluate serum mucin 3A (MUC3A) as a candidate biomarker for extrahepatic cholangiocarcinoma (EHCC).

PATIENTS AND METHODS

35 Patients with EHCC, 30 patients with pancreatic cancer, 35 patients with gallbladder carcinoma and 78 patients with benign biliary disease were enrolled during January 2015 to January 2016. Serum MUC3A, carbohydrate antigen 19-9 (CA19-9) and carcinoembryonic antigen (CEA) were measured in these patients. Pathology reports of patients with EHCC were collected.

RESULTS

(1) The serum levels of MUC3A (87.3 ± 10.8 ng/ml) in patients with EHCC were higher than in patients with pancreatic cancer (63.2 ± 7.7 ng/ml, P < 0.001), patients with gallbladder carcinoma (59.0 ± 10.3 ng/ml, P < 0.001) and patients with benign biliary disease (56.6 ± 13.1 ng/ml, P < 0.001). (2) ROC analysis showed that using MUC3A could clearly distinguish patients with EHCC from those without EHCC with a threshold of 73.2 ng/ml. (3) According to ROC analysis, the sensitivity, specificity, and accuracy of serum MUC3A for diagnosis of EHCC were 94.3%, 89.5% and 90.4%, respectively, which were all significantly higher than CA19-9 and CEA. (4) The serum levels of MUC3A at 1 month post-operatively in 35 patients with EHCC were decreased compared to pre-operative levels (51.8 ± 5.6 vs. 87.3 ± 10.8 ng/ml, P < 0.01). (5) Compared with 20 patients with low MUC3A levels (≤88.8 ng/ml), 15 patients with high MUC3A levels (>88.8 ng/ml) had higher percentage of lymph node metastasis (66.7% vs. 25%, P = 0.014), surrounding tissue infiltration (80% vs. 30%, P = 0.003), and UICC staging IIa-III (86.7% vs. 35%, P = 0.002).

CONCLUSION

The diagnostic efficiency for EHCC of MUC3A is obviously superior to CA19-9 and CEA, and a high level of serum MUC3A indicates a poor prognosis, therefore, MUC3A can be used as a potential diagnostic and prognostic biomarker for EHCC.

Genetics of gallstone disease

Gallstone disease (GSD) is one of the most common biliary tract disorders worldwide. The prevalence, however, varies from 5.9-21.9% in Western society to 3.1-10.7% in Asia. Most gallstones (75%) are silent. Approximately half of symptomatic gallstone carriers experience a second episode of biliary pain within 1 year. These individuals are at increased risk of developing acute cholecystitis, acute cholangitis, and biliary pancreatitis. As can be expected, these complications burden health care systems because of their invasive nature and surgical cost. Factors that contribute to gallstone formation include supersaturation of cholesterol in bile, gallbladder hypomotility, destabilization of bile by kinetic protein factors, and abnormal mucins. Epidemiologic studies have implicated multiple environmental factors and some common genetic elements in gallstone formation. Genetic factors that influence gallstone formation have been elaborated from linkage studies of twins, families, and ethnicities. Accumulating evidence suggests that genetic factors play a role in GSD.

Mucin genes in gallstone disease

Gallstone disease is a complex disorder that can be caused by environmental influences, common genetic factors and their interactions. Three major pathogenic abnormalities are considered to involve in gallstone formation: cholesterol supersaturation in bile, precipitation and nucleation of excess cholesterol, and gallbladder hypomotility, while, mucin takes part in the cholesterol nucleation process. Up to date, more than 20 mucin genes have been reported, 9 of them are identified at the mRNA and/or protein level in native gallbladder and its associated diseases. In the gallbladder, mucin is essential for best protection against detergent effect of high concentration of bile acids. Over the past decade, the properties, expressions and functions of the gallbladder mucins are delineated in animal and human studies. Alteration expressions of mucins are thought to response during the pathogenesis of gallstone formation. Moreover, recent genetic association study demonstrated mucin gene polymorphisms may also influence susceptibility to gallstone disease. This review is not to provide a complete coverage of all the aspects of mucin glycoproteins, but focus on the role and expression of mucins involve in the regulation of cholelithogenesis.

Concept of the pathogenesis and treatment of cholelithiasis

Gallstone disease (GD) is a chronic recurrent hepatobiliary disease, the basis for which is the impaired metabolism of cholesterol, bilirubin and bile acids, which is characterized by the formation of gallstones in the hepatic bile duct, common bile duct, or gallbladder. GD is one of the most prevalent gastrointestinal diseases with a substantial burden to health care systems. GD can result in serious outcomes, such as acute gallstone pancreatitis and gallbladder cancer. The epidemiology, pathogenesis and treatment of GD are discussed in this review. The prevalence of GD varies widely by region. The prevalence of gallstone disease has increased in recent years. This is connected with a change in lifestyle: reduction of motor activity, reduction of the physical load and changes to diets. One of the important benefits of early screening for gallstone disease is that ultrasonography can detect asymptomatic cases, which results in early treatment and the prevention of serious outcomes. The pathogenesis of GD is suggested to be multifactorial and probably develops from complex interactions between many genetic and environmental factors. It suggests that corticosteroids and oral contraceptives, which contain hormones related to steroid hormones, may be regarded as a model system of cholelithiasis development in man. The achievement in the study of the physiology of bile formation and the pathogenesis of GD has allowed expanding indications for therapeutic treatment of GD.