Cholangiocyte

Last updated
Cholangiocyte
Details
System Biliary system
Location Bile duct
Function Epithelium
Identifiers
Latin cholangiocytus
TH H3.04.05.0.00011
Anatomical terms of microanatomy

Cholangiocytes are the epithelial cells of the bile duct. [1] They are cuboidal epithelium in the small interlobular bile ducts, but become columnar and carbonate-secreting in larger bile ducts approaching the porta hepatis and the extrahepatic ducts. They contribute to hepatocyte survival by transporting bile acids.

Contents

Function

In the healthy liver, cholangiocytes contribute to bile secretion via release of bicarbonate and water. Several hormones and locally acting mediators are known to contribute to cholangiocyte fluid/electrolyte secretion. These include secretin, acetylcholine, ATP, and bombesin.

Cholangiocytes act through bile-acid independent bile flow, which is driven by the active transport of electrolytes. In contrast, hepatocytes secrete bile through bile-acid dependent bile flow, which is coupled to canalicular secretion of bile acids via ATP-driven transporters. This results in passive transcellular and paracellular secretion of fluid and electrolytes through an osmotic effect.

Clinical significance

Disordered functioning of cholangiocytes is at the center of a variety of pathological conditions known as "cholangiopathies." These diseases include primary biliary cirrhosis, primary sclerosing cholangitis, AIDS cholangiopathy, disappearing bile duct syndromes, Alagille's syndrome, cystic fibrosis, and biliary atresia. Often either the best or the only curative treatment option for cholangiopathies is liver transplantation, and as a group, cholangiopathies account for a substantial percentage of both adult and pediatric liver transplants. [2]

Research

Active scientific investigation of cholangiocytes focuses on such diverse processes as mechanisms of fluid/electrolyte secretion, regulation of cholangiocyte proliferation, roles of cholangiocytes in the pathogenesis of liver fibrosis and cirrhosis, and cholangiocyte apoptosis. Specific investigation of individual cholangiopathies is also pursued actively. [1]

Related Research Articles

<span class="mw-page-title-main">Gallstone</span> Disease where stones form in the gallbladder

A gallstone is a stone formed within the gallbladder from precipitated bile components. The term cholelithiasis may refer to the presence of gallstones or to any disease caused by gallstones, and choledocholithiasis refers to the presence of migrated gallstones within bile ducts.

<span class="mw-page-title-main">Alcoholic liver disease</span> Medical condition

Alcoholic liver disease (ALD), also called alcohol-related liver disease (ARLD), is a term that encompasses the liver manifestations of alcohol overconsumption, including fatty liver, alcoholic hepatitis, and chronic hepatitis with liver fibrosis or cirrhosis.

<span class="mw-page-title-main">Caroli disease</span> Medical condition

Caroli disease is a rare inherited disorder characterized by cystic dilatation of the bile ducts within the liver. There are two patterns of Caroli disease: focal or simple Caroli disease consists of abnormally widened bile ducts affecting an isolated portion of liver. The second form is more diffuse, and when associated with portal hypertension and congenital hepatic fibrosis, is often referred to as "Caroli syndrome". The underlying differences between the two types are not well understood. Caroli disease is also associated with liver failure and polycystic kidney disease. The disease affects about one in 1,000,000 people, with more reported cases of Caroli syndrome than of Caroli disease.

<span class="mw-page-title-main">Alcoholic hepatitis</span> Medical condition

Alcoholic hepatitis is hepatitis due to excessive intake of alcohol. Patients typically have a history of at least 10 years of heavy alcohol intake, typically 8-10 drinks per day. It is usually found in association with fatty liver, an early stage of alcoholic liver disease, and may contribute to the progression of fibrosis, leading to cirrhosis. Symptoms may present acutely after a large amount of alcoholic intake in a short time period, or after years of excess alcohol intake. Signs and symptoms of alcoholic hepatitis include jaundice, ascites, fatigue and hepatic encephalopathy. Mild cases are self-limiting, but severe cases have a high risk of death. Severe cases may be treated with glucocorticoids. The condition often comes on suddenly and may progress in severity very rapidly.

<span class="mw-page-title-main">Biliary atresia</span> Medical condition

Biliary atresia, also known as extrahepatic ductopenia and progressive obliterative cholangiopathy, is a childhood disease of the liver in which one or more bile ducts are abnormally narrow, blocked, or absent. It can be congenital or acquired. It has an incidence of one in 10,000–15,000 live births in the United States, and a prevalence of one in 16,700 in the British Isles. Biliary atresia is most common in East Asia, with a frequency of one in 5,000.

<span class="mw-page-title-main">Primary biliary cholangitis</span> Autoimmune disease of the liver

Primary biliary cholangitis (PBC), previously known as primary biliary cirrhosis, is an autoimmune disease of the liver. It results from a slow, progressive destruction of the small bile ducts of the liver, causing bile and other toxins to build up in the liver, a condition called cholestasis. Further slow damage to the liver tissue can lead to scarring, fibrosis, and eventually cirrhosis.

<span class="mw-page-title-main">Primary sclerosing cholangitis</span> Medical condition

Primary sclerosing cholangitis (PSC) is a long-term progressive disease of the liver and gallbladder characterized by inflammation and scarring of the bile ducts, which normally allow bile to drain from the gallbladder. Affected individuals may have no symptoms or may experience signs and symptoms of liver disease, such as yellow discoloration of the skin and eyes, itching, and abdominal pain.

<span class="mw-page-title-main">Gastrointestinal disease</span> Medical condition

Gastrointestinal diseases refer to diseases involving the gastrointestinal tract, namely the oesophagus, stomach, small intestine, large intestine and rectum, and the accessory organs of digestion, the liver, gallbladder, and pancreas.

<span class="mw-page-title-main">Ursodeoxycholic acid</span> Metabolite of cholesterol

Ursodeoxycholic acid (UDCA), also known as ursodiol, is a secondary bile acid, produced in humans and most other species from metabolism by intestinal bacteria. It is synthesized in the liver in some species, and was first identified in bile of bears of genus Ursus, from which its name derived. In purified form, it has been used to treat or prevent several diseases of the liver or bile ducts.

<span class="mw-page-title-main">Cholestasis</span> Medical condition

Cholestasis is a condition where bile cannot flow from the liver to the duodenum. The two basic distinctions are an obstructive type of cholestasis where there is a mechanical blockage in the duct system that can occur from a gallstone or malignancy, and metabolic types of cholestasis which are disturbances in bile formation that can occur because of genetic defects or acquired as a side effect of many medications. Classification is further divided into acute or chronic and extrahepatic or intrahepatic.

Progressive familial intrahepatic cholestasis (PFIC) is a group of familial cholestatic conditions caused by defects in biliary epithelial transporters. The clinical presentation usually occurs first in childhood with progressive cholestasis. This usually leads to failure to thrive, cirrhosis, and the need for liver transplantation.

Neonatal cholestasis refers to elevated levels of conjugated bilirubin identified in newborn infants within the first few months of life. Conjugated hyperbilirubinemia is clinically defined as >20% of total serum bilirubin or conjugated bilirubin concentration greater than 1.0 mg/dL regardless of total serum bilirubin concentration. The differential diagnosis for neonatal cholestasis can vary extensively. However, the underlying disease pathology is caused by improper transport and/or defects in excretion of bile from hepatocytes leading to an accumulation of conjugated bilirubin in the body. Generally, symptoms associated with neonatal cholestasis can vary based on the underlying cause of the disease. However, most infants affected will present with jaundice, scleral icterus, failure to thrive, acholic or pale stools, and dark urine.

<span class="mw-page-title-main">Biliary tract</span> Organ system

The biliary tract refers to the liver, gallbladder and bile ducts, and how they work together to make, store and secrete bile. Bile consists of water, electrolytes, bile acids, cholesterol, phospholipids and conjugated bilirubin. Some components are synthesized by hepatocytes ; the rest are extracted from the blood by the liver.

<span class="mw-page-title-main">Liver</span> Vertebrate organ involved in metabolism

The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it is located in the right upper quadrant of the abdomen, below the diaphragm. Its other roles in metabolism include the regulation of glycogen storage, decomposition of red blood cells, and the production of hormones.

Vanishing bile duct syndrome is a loose collection of diseases which leads to the injury to hepatic bile ducts and eventual ductopenia.

<i>S</i>-Nitrosoglutathione Chemical compound

S-Nitrosoglutathione (GSNO) is an endogenous S-nitrosothiol (SNO) that plays a critical role in nitric oxide (NO) signaling and is a source of bioavailable NO. NO coexists in cells with SNOs that serve as endogenous NO carriers and donors. SNOs spontaneously release NO at different rates and can be powerful terminators of free radical chain propagation reactions, by reacting directly with ROO• radicals, yielding nitro derivatives as end products. NO is generated intracellularly by the nitric oxide synthase (NOS) family of enzymes: nNOS, eNOS and iNOS while the in vivo source of many of the SNOs is unknown. In oxygenated buffers, however, formation of SNOs is due to oxidation of NO to dinitrogen trioxide (N2O3). Some evidence suggests that both exogenous NO and endogenously derived NO from nitric oxide synthases can react with glutathione to form GSNO.

<span class="mw-page-title-main">Obeticholic acid</span> Chemical compound

Obeticholic acid (OCA), sold under the brand name Ocaliva, is a semi-synthetic bile acid analogue which has the chemical structure 6α-ethyl-chenodeoxycholic acid. It is used as a medication used to treat primary biliary cholangitis. Intercept Pharmaceuticals Inc. hold the worldwide rights to develop OCA outside Japan and China, where it is licensed to Dainippon Sumitomo Pharma.

<span class="mw-page-title-main">Bilirubin glucuronide</span> Chemical compound

Bilirubin glucuronide is a water-soluble reaction intermediate over the process of conjugation of indirect bilirubin. Bilirubin glucuronide itself belongs to the category of conjugated bilirubin along with bilirubin di-glucuronide. However, only the latter one is primarily excreted into the bile in the normal setting.

Hyperbilirubinemia is a clinical condition describing an elevation of blood bilirubin level due to the inability to properly metabolise or excrete bilirubin, a product of erythrocytes breakdown. In severe cases, it is manifested as jaundice, the yellowing of tissues like skin and the sclera when excess bilirubin deposits in them. The US records 52,500 jaundice patients annually. By definition, bilirubin concentration of greater than 3 mg/ml is considered hyperbilirubinemia, following which jaundice progressively develops and becomes apparent when plasma levels reach 20 mg/ml. Rather than a disease itself, hyperbilirubinemia is indicative of multifactorial underlying disorders that trace back to deviations from regular bilirubin metabolism. Diagnosis of hyperbilirubinemia depends on physical examination, urinalysis, serum tests, medical history and imaging to identify the cause. Genetic diseases, alcohol, pregnancy and hepatitis viruses affect the likelihood of hyperbilirubinemia. Causes of hyperbilirubinemia mainly arise from the liver. These include haemolytic anaemias, enzymatic disorders, liver damage and gallstones. Hyperbilirubinemia itself is often benign. Only in extreme cases does kernicterus, a type of brain injury, occur. Therapy for adult hyperbilirubinemia targets the underlying diseases but patients with jaundice often have poor outcomes.

References

  1. 1 2 Tietz PS, Larusso NF (May 2006). "Cholangiocyte biology". Current Opinion in Gastroenterology. 22 (3): 279–87. doi:10.1097/01.mog.0000218965.78558.bc. PMID   16550043. S2CID   38944986.
  2. Tam, PKH; Yiu, RS; Lendahl, U; Andersson, ER (September 2018). "Cholangiopathies - Towards a molecular understanding". EBioMedicine. 35: 381–393. doi:10.1016/j.ebiom.2018.08.024. PMC   6161480 . PMID   30236451.