Cholesterol gallstones: Focusing on the role of interstitial Cajal-like cells

Cholesterol gallstone (CG) is a common, frequent biliary system disease in China, with a complex and multifactorial etiology. Declined gallbladder motility reportedly contributes to CG pathogenesis. Furthermore, interstitial Cajal-like cells (ICLCs) are reportedly present in human and guinea pig gallbladder tissue. ICLCs potentially contribute to the regulation of gallbladder motility, and aberrant conditions involving the loss of ICLCs and/or a reduction in its pacing potential and reactivity to cholecystokinin may promote CG pathogenesis. This review discusses the association between ICLCs and CG pathogenesis and provides a basis for further studies on the functions of ICLCs and the etiologies of CG.

The deletion of the estrogen receptor α gene reduces susceptibility to estrogen-induced cholesterol cholelithiasis in female mice

Compelling evidence has demonstrated that estrogen is a critical risk factor for gallstone formation and enhances cholesterol cholelithogenesis through the hepatic estrogen receptor α (ERα), but not ERβ. To study the lithogenic mechanisms of estrogen through ERα, we investigated whether the deletion of Erα protects against gallstone formation in ovariectomized (OVX) female mice fed a lithogenic diet and treated with 17β-estradiol (E2) at 0 or 6μg/day for 56days. Our results showed that the prevalence of gallstones was reduced from 100% in OVX ERα (+/+) mice to 30% in OVX ERα (-/-) mice in response to high doses of E2 and the lithogenic diet for 56days. Hepatic cholesterol secretion was significantly diminished in OVX ERα (-/-) mice compared to OVX ERα (+/+) mice even fed the lithogenic diet and treated with E2 for 56days. These alterations decreased bile lithogenicity by reducing cholesterol saturation index of gallbladder bile. Immunohistochemical studies revealed that ERα was expressed mainly in the gallbladder smooth muscle cells. High levels of E2 impaired gallbladder emptying function mostly through the ERα and cholecystokinin-1 receptor pathway, leading to gallbladder stasis in OVX ERα (+/+) mice. By contrast, gallbladder emptying function was greatly improved in OVX ERα (-/-) mice. This markedly retarded cholesterol crystallization and the growth and agglomeration of solid cholesterol crystals into microlithiasis and stones. In conclusion, the deletion of Erα reduces susceptibility to the formation of E2-induced gallstones by diminishing hepatic cholesterol secretion, desaturating gallbladder bile, and improving gallbladder contraction function in female mice.

Obesity and the risk and prognosis of gallstone disease and pancreatitis

Obesity is a risk factor for the formation of cholesterol gallstones and exposes patients to increased risk of gallstone-related complications and cholecystectomy. Rapid weight loss achieved by very low calorie diets or bariatric surgery is also a risk factor for cholelithiasis in obese patients, and therapy should take into account the higher prevalence of gallstones, the possibility of more frequent complications and the need for prophylactic treatment with oral ursodeoxycholic acid during weight loss. Obesity is also frequent in children and adolescents, and the burden of cholesterol cholelithiasis is increasing in this population. The chance to develop acute pancreatitis and the severity of the disease are higher in obese subjects because of specific pathogenic factors, including supersaturated bile and crystal formation, rapid weight loss, and visceral obesity. All health policies aimed at reducing the incidence of obesity worldwide will decrease the incidence of gallstones and gallstone-related complications. The pathophysiological scenarios and the therapeutic implications for obesity, gallstone disease, and pancreatitis are discussed.

Changes of gastrointestinal myoelectric activity and bile acid pool size after cholecystectomy in guinea pigs

AIM: To investigate the bile acid pool size after cholecystectomy whether or not correlated to the gastrointestinal migrating myoelectric complex (MMC) in guinea pigs.

METHODS: Gallbladder motilities were assessed before cholecystectomy. Furthermore, we continuously monitored interdigestive gastrointestinal motilities using bipolar electrodes in conscious guinea pigs before and after surgery at 4 wk in standard diet group and high cholesterol diet (cholesterol gallstone) group. Total bile acid pool sizes were measured by isotope dilution method at meantime.

RESULTS: After cholecystectomy, there were parallel falls in duration of phase I, II, III and MMC cycle duration but increase in amplitude in the guinea pigs with normal gallbladder function, and in the guinea pigs with cholesterol stones. However, There were not significantly differences. On the other hand, the bile acid pool was definitely small in the GS guinea pigs compared to normal guinea pigs and became slightly smaller after cholecystectomy. Similarly, bile acid in gallbladder bile, fecal bile acid was slightly increased in GS guinea pigs after cholecystectomy, to the same degree as normal. These differences, however, were not significant.

CONCLUSION: It is concluded that in the guinea pigs with normal gallbladder function, and in the guinea pigs with cholesterol stones: (1) Cholecystectomy produce a similar but less marked trend in bile acid pool; and (2) MMC are linked to enterohepatic circulation of bile acids, rather than surgery, which is consistent with changes of the bile acid pool size. As a result, gastrointestinal dyskinesia is not involved in occurrence of postchole-cystectomy syndrome.

Gallbladder motor function, plasma cholecystokinin and cholecystokinin receptor of gallbladder in cholesterol stone patients

AIM: To study the interactive relationship of gallbladder motor function, plasma cholecystokinin (CCK) and cholecystokinin A receptor (CCK-R) of gallbladder in patients with cholesterol stone disease.

METHODS: Gallbladder motility was studied by ultrasonography in 33 patients with gallbladder stone and 10 health subjects as controls. Plasma CCK concentration was measured by radioimmunoassay in fasting status (CCK-f) and in 30 min after lipid test meal (CCK-30). Radioligand method was employed to analyze the amount and activity of CCK-R from 33 gallstone patients having cholecystectomy and 8 persons without gallstone died of severe trauma as controls.

RESULTS: The percentage of cholesterol in the gallstone composition was more than 70%. The cholesterol stone type was indicated for the patients with gallbladder stone in this study. Based on the criterion of gallbladder residual fraction of the control group, 33 gallstone patients were divided into two subgroups, contractor group (14 cases) and non-contractor group (19 cases). The concentration of CCK-30 was significantly higher in non-contractor group than that in both contractor group and control group (55.86±3.86 pmol/L vs 37.85±0.88 pmol/L and 37.95±0.74 pmol/L, P<0.01), but there was no difference between contractor group and control group. Meanwhile no significant difference of the concentration of CCK-f could be observed among three groups. The amount of CCK-R was lower in non-contractor group than those in both control group and contractor group (10.27±0.94 fmol/mg vs 24.59±2.39 fmol/mg and 22.66±0.55 fmol/mg, P<0.01). The activity of CCK-R shown as KD in non-contractor group decreased compared to that in control group and contractor group. Only was the activity of CCK-R lower in contractor group than that in control group. The ejection fraction correlated closely with the amount of CCK-R (r = 0.9683, P<0.01), and the concentration of CCK-30 correlated negatively with the amount of CCK-R closely (r = -0.9627, P<0.01).

CONCLUSION: The distinctive interactive relationship of gallbladder emptying, plasma CCK and CCK-R in gallbladder from this study suggested that the defect of CCK-R may be a key point leading to the impairment of gallbladder motor function and the pathogenesis of cholesterol gallstone formation may differ in two subgroups of gallstone patient, gallbladder non-contractor group or contractor group.