Effects of sphincter of Oddi motility on the formation of cholesterol gallstones

Sphincter of Oddi Dysfunction Induces Gallstone by Inhibiting the Expression of ABCB11 via PKC-α

The abnormal increase of Oddi sphincter pressure and total bile duct pressure may play an important role in the formation of cholesterol stones, but the specific molecular mechanism is still unclear. This study aims to investigate it through in vitro and in vivo experiments. A mouse model of Oddi sphincter dysfunction was constructed by stone-inducing diet. We compared the two groups with PKC-α inhibitor GÖ6976 and PKC-α agonist thymeleatoxin. Oddi sphincter pressure and total bile duct pressure were measured. Biochemical analysis of total cholesterol, bile acid and bilirubin was then conducted. The histopathologic changes of bile duct were observed by HE staining and the ultrastructure of liver cells and surrounding tissues was observed by transmission electron microscopy. Through the above experiments, we found that the change of PKC-α expression may affect the formation process of gallstones. The relationship between PKC-α and ABCB11 was further verified by in vitro and in vivo experiments. Our results suggest that ABCB11 and PKC-α are co-expressed in the tubule membrane of hepatocytes and interact with each other in hepatocytes. The high cholesterol diet further enhances the activation of PKC-α and thus reduces the expression of ABCB11. The formation of cholesterol stones is associated with the down-regulation of ABCB11 expression in the tubule membrane of hepatocytes due to kinase signaling. This is the first study to demonstrate that sphincter of Oddi dysfunction induces gallstones through PKC-α inhibition of ABCB11 expression.

Effect of sphincter of Oddi dysfunction on the abundance of biliary microbiota (biliary microecology) in patients with common bile duct stones

Objective

Biliary calculi, a common benign disease of the gastrointestinal tract, are affected by multiple factors, including diet, lifestyle, living environment, and personal and genetic background. Its occurrence is believed to be related to a change in biliary microbiota. Approximately 10%-20% of symptomatic patients with cholecystolithiasis have choledocholithiasis, resulting in infection, abdominal pain, jaundice, and biliary pancreatitis. This study aimed to determine whether a dysfunction in the sphincter of Oddi, which controls the outflow of bile and separates the bile duct from the intestine, leads to a change in biliary microbiota and the occurrence of biliary calculi.

Methods

Forty patients with cholecystolithiasis and choledocholithiasis were prospectively recruited. Bile specimens were obtained, and biliary pressure was measured during and after surgery. The collected specimens were analyzed with 16S rRNA gene to characterize the biliary microbiota. The risk factors of common bile duct calculi were analyzed numerically combined with the pressure in the sphincter of Oddi.

Results

Different biliary microbiota were found in all cases. Patients with sphincter of Oddi dysfunction had significantly increased biliary microbiota as well as significantly higher level of systemic inflammation than patients with normal sphincter of Oddi.

Conclusions

The systemic inflammatory response of patients with sphincter of Oddi dysfunction is more severe, and their microbial community significantly differs from that of patients with normal sphincter of Oddi, which makes biliary tract infection more likely; furthermore, the biliary tract of patients with sphincter of Oddi dysfunction has more gallstone-related bacterial communities.

α-Subunit Tyrosine Phosphorylation Is Required for Activation of the Large Conductance Ca2+-Activated Potassium Channel in the Rabbit Sphincter of Oddi

Large conductance Ca²⁺-activated potassium (BK_Ca) channels are regulated by intracellular free Ca²⁺ concentrations ([Ca²⁺]i) and channel protein phosphorylation. In hypercholesterolemia (HC), motility impairment of the sphincter of Oddi (SO) is associated with abnormal [Ca²⁺]i accumulation in smooth muscle cells of the rabbit SO (RSOSMCs), which is closely related to BK_Ca channel activity. However, the underlying mechanisms regulating channel activity remain unclear. In this study, an HC rabbit model was generated and used to investigate BK_Ca channel activity of RSOSMCs via SO muscle tone measurement in vitro and manometry in vivo, electrophysiological recording, intracellular calcium measurement, and Western blot analyses. BK_Ca channel activity was decreased, which correlated with [Ca²⁺]i overload and reduced tyrosine phosphorylation of the BK_Ca α-subunit in the HC group. The abnormal [Ca²⁺]i accumulation and decreased BK_Ca channel activity were partially restored by Na₃VO₄ pretreatment but worsened by genistein in RSOSMCs in the HC group. This study suggests that α-subunit tyrosine phosphorylation is required for [Ca²⁺]i to activate BK_Ca channels, and there is a negative feedback between the BK_Ca channel and the L-type voltage-dependent Ca²⁺ channel that regulates [Ca²⁺]i. This study provides direct evidence that tyrosine phosphorylation of BK_Ca α-subunits is required for [Ca²⁺]i to activate BK_Ca channels in RSOSMCs, which may be the underlying physiological and pathologic mechanism regulating the activity of BK_Ca channels in SO cells.

Clinical application and research progress of extracellular slow wave recording in the gastrointestinal tract

The physiological function of the gastrointestinal (GI) tract is based on the slow wave generated and transmitted by the interstitial cells of Cajal. Extracellular myoelectric recording techniques are often used to record the characteristics and propagation of slow wave and analyze the models of slow wave transmission under physiological and pathological conditions to further explore the mechanism of GI dysfunction. This article reviews the application and research progress of electromyography, bioelectromagnetic technology, and high-resolution mapping in animal and clinical experiments, summarizes the clinical application of GI electrical stimulation therapy, and reviews the electrophysiological research in the biliary system.

Cholecystectomy reduces the severity of subsequent idiopathic acute pancreatitis

BACKGROUND

Acute pancreatitis (AP) is a common digestive system disease, and its incidence is increasing year by year. Although some clinical studies have indicated that cholecystectomy can reduce the risk of recurrent pancreatitis after acute biliary pancreatitis (ABP), it is not clear whether cholecystectomy would affect the severity of subsequent AP.

METHODS

In this study, we combined computed tomography scoring index (CTSI), bedside index for severity in AP (BISAP), and clinical manifestations grading of AP with propensity score matching (PSM), after correction for baseline confounding factors, to respectively explore the influence of cholecystectomy on the severity of subsequent pancreatitis in 527 AP patients.

RESULTS

The results showed that ABP (231/527) is more common in female patients and elderly patients (P < 0.001). Age, amylase, creatinine, blood urea nitrogen, and aspartate aminotransferase levels of patients with ABP at admission were higher than those of non-biliary pancreatitis (296/527), and the levels of albumin, hematocrit, and blood glucose were lower (P < 0.050). Further, compared with the unresected group (458/527), patients after cholecystectomy (69/527) had less white blood cells and higher level of albumin (P < 0.050). Patients had lower clinical manifestation grade (P = 0.019) and CTSI grade (P < 0.008) after cholecystectomy. After PSM correction, there was no difference in biochemical parameters between the cholecystectomy group and the non-cholecystectomy group, but differences in clinical manifestation grade (P = 0.039) and CTSI grade (P = 0.013) remained. We also found that cholecystectomy reduced the frequency of biliary pancreatitis (30.4% vs. 45.9%, P < 0.050). Finally, we found that cholecystectomy could reduce the severity of subsequent idiopathic AP.

CONCLUSION

Cholecystectomy could reduce the severity of subsequent idiopathic AP and the frequency of biliary pancreatitis.

Changes in the interstitial cells of Cajal in the gallbladder of guinea pigs fed a lithogenic diet

Cholesterol cholelithiasis is a common disease and gallbladder hypomotility may underlie its pathogenesis. Interstitial cells of Cajal (ICCs) in the gallbladder serve vital roles in regulating gallbladder motility. The aim of the present study was to investigate changes in gallbladder ICCs during the development of cholesterol cholelithiasis. A total of 40 male guinea pigs were randomly assigned to four groups and fed a standard diet (SD) or lithogenic diet (LD) for 2 or 8 weeks. The LD significantly increased the total cholesterol levels in the serum and bile, as well as the serum levels of high-density lipoprotein-cholesterol and low-density lipoprotein-cholesterol after 2 and 8 weeks. The LD also significantly increased and decreased the number of gallbladder ICCs at 2 and 8 weeks, respectively, by regulating the stem cell factor/C-kit pathway. Moreover, the ultrastructure of gallbladder ICCs was significantly altered after 8 weeks, and the protein expression levels of connexin 43 in the gallbladder were differentially altered after 2 and 8 weeks. Finally, cholecystokinin receptor type A (CCK1R) expression in the gallbladder was assessed. In gallbladder ICCs, its expression was significantly increased and decreased after 2 and 8 weeks, respectively. In conclusion, these results demonstrate that the density, ultrastructure and CCK1R expression levels of gallbladder ICCs are differentially altered at various stages of cholesterol cholelithiasis progression, indicating that gallbladder ICCs may be considered a potential therapeutic target for treatment of cholesterol cholelithiasis.

Endoscopic endoclip papilloplasty preserves sphincter of oddi function

BACKGROUND

Endoscopic sphincterotomy (EST) can destroy sphincter of Oddi (SO) structure and function. The purpose of this study was to assess the feasibility of endoscopic endoclip papilloplasty (EEPP) in restoring SO function after EST.

METHODS

Seven 26-week-old domestic pigs were divided into control and EEPP groups. Necropsy and haematoxylin-eosin staining plus anti-α-smooth muscle actin (α-SMA) staining of papilla and sphincter of Oddi manometry (SOM) were conducted in animals at three independent time points.

RESULTS

EST and EEPP were safely performed in all 7 pigs without serious adverse events. For primary outcome, compared to the controls, EEPP generated smaller dilation and less inflammation. Fibrous repair of the papilla was observed at 24 weeks after EEPP. For secondary outcome, in the control group, SO basal pressure (17.25 ± 18.14 to 5.50 ± 0.71 mmHg), SO contraction amplitude (46.00 ± 19.20 to 34.50 ± 48.79 mmHg), peak (4.50 ± 4.04 to 1.50 ± 2.12) and frequency (3.05 ± 3.29 to 1.41 ± 2.19/min) were reduced after EST. Further reductions to almost 0 of these SOM parameters were observed 3 weeks later, including common bile duct pressure and SO contraction period. In contrast, in the EEPP group, these manometric data were recovered to pre-EST levels, including CBD pressure (11.5 ± 7.31 vs 11 ± 2.16 mmHg), SO pressure (17.50 ± 17.75 vs 18.20 ± 21.39 mmHg) and SO contraction amplitude (53.67 ± 21.54 vs 60.00 ± 36.08 mmHg). However, no significant differences were observed between control and EEPP groups by Student t test.

CONCLUSIONS

In this porcine study, EEPP accelerated and improved papillary healing after EST, further preserved SO function.

Distribution changes of interstitial cells of Cajal during cholesterol gallstone formation in guinea pigs fed a high cholesterol diet

BACKGROUND

Cholesterol gallstone is commonly observed in patients with gallbladder disorders. Interstitial cells of Cajal (ICCs) in the gallbladder are important for regulating gallbladder motility and have a close relationship with cholelithiasis.

AIM

The aim of this study was to explore changes in the distribution of gallbladder ICCs during cholesterol gallstone formation.

MATERIALS AND METHODS

Thirty guinea pigs were randomly divided into three groups: the control group and study groups. Animals in study groups were fed on high cholesterol diet for 4 weeks or 8 weeks. Animals in the control groups were fed on a standard diet for 8 weeks. Immunohistochemistry was performed to observe the shape, size, morphology, and numbers of ICCs from the neck of the gallbladder to the fundus of the gallbladder, and terminal deoxynucleotidyl transferase dUTP nick-end labeling was performed to detect apoptosis in ICCs from the upper part of the gallbladder to the lower part of the gallbladder.

RESULTS

There were no differences in the shape, size, and morphology of the gallbladder ICCs in all groups. Cholesterol gallstones formed in guinea pigs fed on high cholesterol diet. The numbers of gallbladder ICCs were significantly decreased from the neck of the gallbladder to the fundus of the gallbladder, and gallbladder ICC apoptosis was significantly increased from the upper part of the gallbladder to the lower part of the gallbladder in both guinea pigs fed on high cholesterol diet (all P<0.05).

CONCLUSION

Cholesterol gallstone formation reduced the density of gallbladder ICCs and increased the frequency of apoptotic gallbladder ICCs from the neck of the gallbladder to the fundus of the gallbladder, and these alterations may affect gallbladder ICC function.