Genetic polymorphism of sterol transporters in children with future gallstones

Resistance to Cholesterol Gallstone Disease: Hepatic Cholesterol Metabolism

Cholesterol gallstone disease (CGD) is one of the most common digestive diseases, and it is closely associated with hepatic cholesterol metabolism. Cholesterol gallstones may be caused by abnormal hepatic cholesterol metabolism, such as excessive cholesterol biosynthesis within the liver, interfering with the uptake or export of cholesterol in the liver, and abnormal hepatic cholesterol esterification. In this review, we begin with a brief overview of the clinical diagnosis and treatment of gallstone disease (GSD). Then, we briefly describe the major processes of hepatic cholesterol metabolism and summarize the key molecular expression changes of hepatic cholesterol metabolism in patients with gallstones. We review and analyze the recent advances in elucidating the relationships between these key molecules and CGD, and some targets significantly impacting on CGD via hepatic cholesterol metabolism are also listed. We also provide a significant discussion on the relationship between CGD and nonalcoholic fatty liver disease (NAFLD). Finally, the new discoveries of some therapeutic strategies associated with hepatic cholesterol metabolism to prevent and treat CGD are summarized.

The rs12532734 Polymorphism Near the Solute Carrier 26A3 Gene Locus Is Associated With Gallstone Disease in Children

Gallstones are increasingly frequent in children. In this candidate gene study, we genotyped 5 gene variants ( ANO1 , SPTLC3 , TMEM147 , TNRC6B , rs12532734) from a recent gallstone genome-wide association study (GWAS) in a cohort of 214 children with gallstones and 172 gallstone-free adult controls. In total, 138 genotyped children presented with symptomatic gallstone disease, 47 underwent cholecystectomy, and 126 received ursodeoxycholic acid (UDCA) as therapy for stones. Among 5 tested variants, the rs12532734 polymorphism modulated the gallstone risk in the studied cohort. Its genotype distribution significantly ( P = 0.025) departed from the Hardy-Weinberg equilibrium among cases, and the common allele was associated with increased odds of developing gallstones at young age (OR = 1.69, P = 0.014). SLC26A3 is the nearest gene to rs12532734 and is involved in the transepithelial bicarbonate and chloride transport. The association of rs12532734 with pediatric gallstones is a novel finding warranting further investigations also with regard to biliary bicarbonate flux and bile composition.

The Etiology of Cholelithiasis in Children and Adolescents-A Literature Review

The incidence of gallstone disease has increased in recent years. The pathogenesis of cholelithiasis is not fully understood. The occurrence of the disease is influenced by both genetic and environmental factors. This article reviews the literature on cholelithiasis in children, with the exception of articles on hematological causes of cholelithiasis and cholelithiasis surgery. The aim of this review is to present the latest research on the pathogenesis of gallstone disease in children. The paper discusses the influence of all factors known so far, such as genetic predisposition, age, infections, medications used, parenteral nutrition, and comorbidities, on the development of gallstone disease. The course of cholelithiasis in the pediatric population is complex, ranging from asymptomatic to life-threatening. Understanding the course of the disease and predisposing factors can result in a faster diagnosis of the disease and administration of appropriate treatment.

Common variant p.D19H of the hepatobiliary sterol transporter ABCG8 increases the risk of gallstones in children

INTRODUCTION

Gallstones are increasingly common in children. Genetic analyses of adult cohorts demonstrated that the sterol transporter ABCG8 p.D19H and Gilbert UGT1A1*28 variants enhance the odds of developing gallstones. The genetic background of common lithiasis in children remains unknown.

METHODS

Overall, 214 children with gallstone disease (1 month-17 years, 107 boys) were inclueded. The control cohorts comprised 214 children (age 6-17 years, 115 boys) and 172 adults (age 40-92 years, 70 men) without gallstones. The ABCG8 p.D19H and UGT1A1*28 polymorphisms as well as ABCB4 (c.504C>T rs1202283, c.711A>T rs2109505) and NPC1L1 variants (p.V1296V rs217434, c.-18C>A rs41279633) were genotyped using TaqMan assays. Serum concentrations of plant sterols and cholesterol precursors were measured by gas chromatography/mass spectrometry.

RESULTS

The ABCG8 risk allele was associated with an increased risk of stones (OR = 1.82, p = .03). Children carrying the p.19H allele presented with lower serum concentrations of surrogate markers of intestinal cholesterol absorption and decreased ratios of phytosterols to the cholesterol precursor desmosterol. Carriers of the common NPC1L1 rs217434 allele had an increased gallstone risk compared with stone-free adults (OR 1.90, p < .01). This variant also affected the ratio of phytosterols to cholesterol precursors (p = .03). Other tested variants were not associated with gallstone risk.

CONCLUSIONS

The p.D19H ABCG8 and, to a lesser extent, NPC1L1 rs217434 variants increase the risk of early-onset gallstone formation. These results point to the presence of a common lithogenic pathway in children and adults.

Genetic variation and intestinal cholesterol absorption in humans: A systematic review and a gene network analysis

Intestinal cholesterol absorption varies widely between individuals, which may translate into differences in responsiveness to cholesterol-lowering drugs or diets. Therefore, understanding the importance of genetic variation on cholesterol absorption rates and the complex intestinal cholesterol network is important. Based on a systematic review, genetic variants in seven genes (ABCG5, ABCG8, ABO, APOE, MTTP, NPC1L1, and LDLR) were identified that were associated with intestinal cholesterol absorption. No clear associations were found for variants in APOA4, APOB, CETP, CYP7A1, HMGCR, SCARB1, SLCO1B1, and SREBF1. The seven genes were used to construct an intestinal cholesterol absorption network. Finally, a network with fifteen additional genes (APOA1, APOA4, APOB, APOC2, APOC3, CETP, HSPG2, LCAT, LDLRAP1, LIPC, LRP1, OLR1, P4HB, SAR1B, and SDC1) was generated. The constructed network shows that cholesterol absorption is complex. Further studies are needed to validate and improve this network, which may ultimately lead to a better understanding of the wide inter-individual variability in intestinal cholesterol absorption and the development of personalized interventions.

Genome-wide meta-analysis of phytosterols reveals five novel loci and a detrimental effect on coronary atherosclerosis

Phytosterol serum concentrations are under tight genetic control. The relationship between phytosterols and coronary artery disease (CAD) is controversially discussed. We perform a genome-wide meta-analysis of 32 phytosterol traits reflecting resorption, cholesterol synthesis and esterification in six studies with up to 9758 subjects and detect ten independent genome-wide significant SNPs at seven genomic loci. We confirm previously established associations at ABCG5/8 and ABO and demonstrate an extended locus heterogeneity at ABCG5/8 with different functional mechanisms. New loci comprise HMGCR, NPC1L1, PNLIPRP2, SCARB1 and APOE. Based on these results, we perform Mendelian Randomization analyses (MR) revealing a risk-increasing causal relationship of sitosterol serum concentrations and CAD, which is partly mediated by cholesterol. Here we report that phytosterols are polygenic traits. MR add evidence of both, direct and indirect causal effects of sitosterol on CAD.

Risk factors, manifestations, diagnosis and treatment of cholelithiasis in children

Cholelithiasis in children refers to cholelithiasis or choledocholithiasis in newborns, infants and adolescents, including a series of symptoms and complications related to stones. The incidence rate of cholelithiasis in children is far lower than that in adults. However, the detection rate of cholelithiasis in children has risen in recent years. The aetiology of cholelithiasis in children is complex, and the pathogenesis is still unclear. According to existing studies, cholelithiasis in children may be related to sex and hormones, obesity, drugs, haemolytic diseases, genetic factors, chemokines, abnormal biliary tract formation, ileal surgery, total parenteral nutrition and other factors. In addition, there is a large occurrence of idiopathic cholelithiasis in children with unknown aetiology. The clinical manifestations of cholelithiasis in children are not completely the same as those in adults, mainly due to the different ages and causes. At present, there is no consensus on the clinical treatment of cholelithiasis in children. Follow-up and observation, drug dissolution and surgical treatment are all treatment methods for children with cholelithiasis. This study reviewed the related literature reports of cholelithiasis in children and summarized the risk factors, clinical manifestations, diagnosis and treatment of cholelithiasis in children to improve the understanding, diagnosis, and treatment of cholelithiasis in children.

Altered Bile Transporter Expression and Cholesterol Metabolism in Children With Cholesterol and Pigment Gallstones

OBJECTIVES

We elucidated pathophysiology of pediatric gallstone disease by assessing liver expression of bile transporters in relation to bile acids and surrogates of cholesterol absorption and synthesis in serum and gallstones.

METHODS

RNA expression of canalicular bile transporters in liver biopsies from 32 pediatric gallstone patients and from 6 liver donors (controls) was measured by qRT-PCR (quantitative real-time reverse transcription polymerase chain reaction). Concentrations of cholesterol and precursors, plant sterols and bile acids in gallstones, and in serum of the patients and 82 healthy children were measured. Primary outcomes were the difference in RNA expressions and serum sterol profiles between patients and controls.

RESULTS

Cholesterol stones (CS; n = 15) contained cholesterol >42% and pigment stones (PS; n = 17) <9% of weight. CS patients had markedly lower serum plant sterols (absorption) and higher cholesterol precursors (synthesis) than PS patients or healthy controls. CS contained several times more cholesterol precursors and less plant sterols relative to cholesterol than PS, which were enriched by primary bile acids (12-5.2-fold, P < 0.001). Liver RNA expression of ABCG5/G8 was similarly increased 2.5- to 1.8-fold (P < 0.002) in CS and PS patients, whereas PS patients had higher ABCB11 expression (P < 0.05). In PS bile acid concentration correlated with gallstone plant sterols (R = 0.83, P < 0.0001), and ABCG5 expression with ABCB11 expression (R = 0.27, P = 0.03).

CONCLUSIONS

In CS, upregulation of ABCG5/G8 expression associates with low absorption and high gallstone content of cholesterol. In PS, activation of bile acid transport by ACBC11 interconnects with hepatic upregulation of ABCG5/G8 enriching PS with bile acids and plant sterols.