Interactions between gall bladder bile and mucosa; relevance to gall stone formation

Combination treatment with n-3 polyunsaturated fatty acids and ursodeoxycholic acid dissolves cholesterol gallstones in mice

The increasing prevalence of cholesterol gallstone disease places an economic burden on the healthcare system. To identify novel therapeutics, we assessed the effects of n-3 polyunsaturated fatty acids (PUFA) in combination with UDCA in a mouse model of cholesterol gallstones. Gallstone dissolution, gallbladder wall thickness, mucin gene expression in the gallbladder, and levels of phospholipids, cholesterol, and bile acids in bile and serum were analysed. RNA was extracted from the liver for mRNA sequencing and gene expression profiling. Combination treatment resulted in greater gallstone dissolution compared with the control group, and PUFA and combination treatments reduced the thickness of the gallbladder wall. Expression levels of mucin genes were significantly lower in the UDCA, PUFA, and combination groups. Transcriptome analyses revealed that combination treatment modulated hepatic lipid metabolism. The PUFA and combination groups showed elevated bile phospholipid and bile acid levels and a lower cholesterol saturation index. Combination treatment with PUFA and UDCA dissolves cholesterol gallstones in mice by decreasing mucin production, increasing levels of phospholipids and bile acids in bile, and decreasing cholesterol saturation. Further studies of the therapeutic effects of combination PUFA and UDCA treatment in patients with cholesterol gallstones are warranted.

The role of the gallbladder in humans

The basic function of the gallbladder in humans is one of protection. The accumulation of the primary bile acids (cholic acid and chenodeoxycholic acid) in the gallbladder reduces the formation of the secondary bile acids (deoxycholic acid and lithocholic acid), thus diminishing their concentration in the so-called gallbladder-independent enterohepatic circulation and protecting the liver, the stomach mucosa, the gallbladder, and the colon from their toxic hydrophobic effects. The presence or absence of the gallbladder in mammals is a determining factor in the synthesis of hydrophobic or hydrophilic bile acids. Because the gallbladder contracts 5-20 min after food is in the stomach and the "gastric chyme" moves from the stomach to the duodenum 1-3 h later, the function of the gallbladder bile in digestion may be insignificant. The aim of this article was to provide a detailed review of the role of the gallbladder and the mechanisms related to bile formation in humans.

Mucin glycoarray in gastric and gallbladder epithelia

BACKGROUND

Mucins are critical cytoprotective glycoproteins and alterations of epithelial gastric mucins have been described in different pathological conditions. The purpose of the present study was to evaluate the putative usefulness of mucins in understanding the progression of gastric cancer and gallstone formation in a better perspective.

METHODS

Formalin-fixed paraffin-embedded gastric biopsy specimens and surgically resected gallbladder tissue samples were sectioned. Alcian Blue (AB) staining was performed to identify sialomucins (staining blue at pH 2.5) and sulfomucins (staining brown at pH 1.0) and then Periodic acid-Schiff's (PAS) staining to visualize the neutral mucins (staining magenta).

RESULTS

In normal gastric and gallbladder mucosae, we found that neutral mucins were predominant, whereas in intestinal metaplasia, gastric carcinoma and stone-containing gallbladder, a significant increase of acidic mucins was found.

CONCLUSION

We suggest that the sulfomucins have a greater role in gallstone formation than the neutral mucins and also that the sialomucins and sulfomucins play an important role in cancer progression and metastasis. Our results challenge the glycobiologists to delve deeper in elucidating the role of mucins in gastric malignancy and in gallstone formation.

Clinical correlation of gallstone disease in a Chinese population in Taiwan: Experience at Cheng Hsin General Hospital

AIM: To explore the prevalence of gallstone disease (GSD) in Taiwan and condition-associated factors related to it.

METHODS: We studied a total of 2386 healthy adults (1235 males and 1151 females) voluntarily admitted to Cheng Hsin General Hospital for a paid physical check-up between January 2002 and December 2002. Blood samples and ultrasound sonography results were collected.

RESULTS: The overall prevalence of GSD among this study-population was 5.3%, including 1.7% (n = 40) having a single stone, 2.3% (n = 55) having multiple stones, and 1.3% (n = 31) having cholecystectomy. The prevalence revealed a statistically significant increase with increasing age (P < 0.0001). Females exhibited a greater prevalence of multiple stones than did males (3.0% vs 1.7%, P = 0.04). Using multiple logistic regression analysis, the following appeared to be significantly related to the prevalence of GSD: older age (40-49 years vs <40 years, OR = 1.63 [95% CI: 0.76-3.48], 50-59 years vs <40 years, OR = 4.93 [95% CI: 2.43-9.99], 60-69 years vs <40 years, OR = 6.82 [95% CI: 3.19-14.60], ≥70 years vs <40 years, OR = 10.65 [95% CI: 4.78-23.73]), higher BMI (≥27 kg/m² vs <24 kg/m², adjusted OR = 1.74 [95% CI: 1.04-2.88]), and higher FPG (≥ 126 mg/dL vs <110 mg/dL, OR = 1.71, 95%CI: 1.01-2.96).

CONCLUSION: Older age (≥50 years), obesity (BMI ≥27 kg/m²), and type 2 diabetes (FPG ≥126 mg/dL) are associated with the prevalence of GSD.

Endothelin content, expression, and receptor type in normal and diseased human gallbladder

The aims of this study were to characterize the endothelin (ET) system in human gallbladder by determining (1) the tissue content of ET-1 and ET-2 by ELISA; (2) the expression of mRNA of the ET precursors preproendothelin-1, -2, and -3; and (3) mRNA expression for the ETA and ETB receptors. Median content of ET-1/2 was significantly reduced in severely inflamed gallbladders compared to gallbladders with mild inflammation. There was an inverse correlation between content of ET-1/2 and inflammation score. mRNA for preproendothelin-2 was highly expressed in all samples, whereas mRNA for preproendothelin-1 was present in negligible quantities and mRNA for preproendothelin-3 was undetectable. mRNA for ETA receptors was expressed in all samples analyzed, whereas mRNA for ETB receptors was expressed at a much lower level. This study demonstrates the presence of ET-1/2 in human gallbladder. ET-1/2 content is decreased with increasing degrees of histological inflammation. ET-2 is likely to be the physiologically significant endothelin isopeptide expressed and ETA receptors appear to predominate in the human gallbladder.

Prevalence and incidence of gallstones in liver cirrhosis

BACKGROUND

Our aim was to assess the prevalence and incidence of gallstone disease in patients with liver cirrhosis and to identify risk factors for cholecystolithiasis.

METHODS

We studied a cohort of 313 patients with liver cirrhosis confirmed by histology and/or laparoscopy and 357 patients free of liver disease, who had been referred for ultrasonographic examination of the upper abdomen. Hepatobiliary ultrasonography was performed when liver cirrhosis was diagnosed and every 6 months thereafter. Risk factors for cholelithiasis (age, gender, diet, pregnancy, diabetes, family history of cholelithiasis, etiology of cirrhosis, decompensated disease) were assessed.

RESULTS

The overall prevalence of gallstones in cirrhotic patients was 23.3%. In controls, the overall prevalence of cholecystolithiasis was 16.8%. After a median follow-up period of 65 months, 30 patients developed gallstones. The calculated annual incidence was 3.4%.

CONCLUSIONS

Given that the prevalence of gallstone disease is higher in cirrhotics than in noncirrhotic patients, cirrhosis of the liver may be considered a risk factor for cholecystolithiasis.

Characterization of glycoproteins in the epithelial cells of human and other mammalian gallbladder. A review

The mammalian gallbladder mucosa is lined by a simple columnar epithelium. Typical surface epithelial cells (principal cells) contain short microvilli, secretory granules, dense bodies, mitochondria and Golgi apparatus. Dense bodies are thought to be lysosomes. Secretory granules contain mucous glycoproteins which are released to the lumen by exocytosis. Oligosaccharide side chains of mucous glycoproteins may provide a favorable environment for nucleation of cholesterol in gallstone formation; therefore they have been studied during the past decades. Histochemical techniques allow the in situ identification of carbohydrates at both the cellular and subcellular levels. The oligosaccharide chains of principal cell mucous glycoproteins have been studied by classical histochemical techniques (PAS, alcian blue, HID, etc). These techniques indicate that mammalian gallbladder mucous glycoproteins are heavily sulphated, whereas sialic acid residues are scarce. Neutral mucins have not been described in the mammalian gallbladder. Electron microscopic studies have located the oligosaccharide chains in secretory granules and Golgi apparatus. More recently, lectins (molecules which specifically recognize and bind with different saccharides or saccharide sequences) have been applied for the intracellular localization of carbohydrate residues. Lectin histochemistry has detected fucose, galactose, N-acetylglucosamine, N-acetylgalactosamine and N-acetylneuraminic acid residues in mucous granules, Golgi apparatus and apical membrane of human principal cells. Mannose residues were observed only in dense bodies. The combined use of deglycosylation procedures and lectin histochemistry has revealed a variety of terminal sequences in oligosaccharide chains of gallbladder mucous glycoproteins: Neu5Ac(alpha 2-3)Gal(beta 1-3)GalNAc, Neu5Ac(alpha 2-3)Gal(beta 1-4)GlcNAc and Gal(beta 1-4)GlcNAc. This technology also suggested the occurrence of N-linked oligosaccharides in the dense bodies of principal cells. Mucous granules mainly contained mucin-type O-linked oligosaccharides although some N-linked chains have also been detected. Gallstone formation is probably a complex process depending on multiple factors. Mucous glycoproteins are one of the factors involved in this process. Histochemical methods offer an excellent research tool for the characterization of glycoproteins in the epithelial cells of the gallbladder, thus contributing to the elucidation of the pathophysiology of gallstone formation.

Can aspirin prevent gallstone recurrence after successful extracorporeal shockwave lithotripsy?

Extracorporeal shockwave lithotripsy (ESWL) is a feasible procedure for the treatment of gallbladder stones in humans. Well-selected patients can achieve stone-free rates in a high percentage. With the gallbladder in situ, these patients are at risk of stone recurrence. There is considerable evidence that aspirin prevents cholesterol gallstone formation in animal models and may prevent gallstone recurrence in man. We attempted to clarify the risk of gallstone recurrence after successful piezoelectric lithotripsy in patients taking either low-dose aspirin or no medication. The first 45 patients shown to be completely free from stones after ESWL were randomized into two groups. One group received 100 mg aspirin daily; the other group did not receive any further medical therapy. Patients were further examined on an average of 19.6 months and 21.9 months, respectively. In the aspirin group the recurrence rate was 18.2%, whereas 21.7% of the patients in the control group developed recurrent stones. Seventy-eight per cent of these patients also had a recurrence of biliary pain. By life-table analysis we had, after a follow-up period of 24 months, a stone recurrence rate of 25% (+/- 11) in the aspirin group and 34% (+/- 14) in the control group. Our results indicate that recurrence prophylaxis remains one of the central questions in ESWL. In this preliminary study, 100 mg of aspirin daily was not able to reduce the recurrence rate after successful ESWL. Further studies will have to show whether higher doses of aspirin or other ways of preventing gallstone after ESWL are possible.

Managing gallbladder disease with prostaglandin inhibitors

Experimental studies have shown that prostaglandins increase hepatic bile flow and gallbladder mucin production, cause gallbladder dysmotility, and inhibit intraluminal fluid absorption, thus promoting gallstone formation. By virtue of their positive actions on gallbladder fluid secretion, muscle contraction, and inflammatory properties, prostaglandins may also have a role in the pain of acute cholecystitis. Although only a few clinical studies of the role of prostaglandin inhibitors in gallbladder disease have been done, results show that use of drugs such as aspirin or other nonsteroidal anti-inflammatory agents may prevent gallstone formation and promptly relieve acute pain.