» Articles » PMID: 34718050

Role of the IgG4-related Cholangitis Autoantigen Annexin A11 in Cholangiocyte Protection

Overview
Journal J Hepatol
Publisher Elsevier
Specialty Gastroenterology
Date 2021 Oct 31
PMID 34718050
Citations 5
Authors
Affiliations
Soon will be listed here.
Abstract

Background & Aims: Annexin A11 was identified as autoantigen in IgG4-related cholangitis (IRC), a B-cell driven disease. Annexin A11 modulates calcium-dependent exocytosis, a crucial mechanism for insertion of proteins into their target membranes. Human cholangiocytes form an apical 'biliary bicarbonate umbrella' regarded as defense against harmful hydrophobic bile acid influx. The bicarbonate secretory machinery comprises the chloride/bicarbonate exchanger AE2 and the chloride channel ANO1. We aimed to investigate the expression and function of annexin A11 in human cholangiocytes and a potential role of IgG1/IgG4-mediated autoreactivity against annexin A11 in the pathogenesis of IRC.

Methods: Expression of annexin A11 in human liver was studied by immunohistochemistry and immunofluorescence. In human control and ANXA11 knockdown H69 cholangiocytes, intracellular pH, AE2 and ANO1 surface expression, and bile acid influx were examined using ratio microspectrofluorometry, cell surface biotinylation, and 22,23-H-glycochenodeoxycholic acid permeation, respectively. The localization of annexin A11-mEmerald and ANO1-mCherry was investigated by live-cell microscopy in H69 cholangiocytes after incubation with IRC patient serum containing anti-annexin A11 IgG1/IgG4-autoantibodies or disease control serum.

Results: Annexin A11 was strongly expressed in human cholangiocytes, but not hepatocytes. Knockdown of ANXA11 led to reduced plasma membrane expression of ANO1, but not AE2, alkalization of intracellular pH and uncontrolled bile acid influx. High intracellular calcium conditions led to annexin A11 membrane shift and colocalization with ANO1. Incubation with IRC patient serum inhibited annexin A11 membrane shift and reduced ANO1 surface expression.

Conclusion: Cholangiocellular annexin A11 mediates apical membrane abundance of the chloride channel ANO1, thereby supporting biliary bicarbonate secretion. Insertion is inhibited by IRC patient serum containing anti-annexin A11 IgG1/IgG4-autoantibodies. Anti-annexin A11 autoantibodies may contribute to the pathogenesis of IRC by weakening the 'biliary bicarbonate umbrella'.

Lay Summary: We previously identified annexin A11 as a specific autoantigen in immunoglobulin G4-related cholangitis (IRC), a B-cell driven disease affecting the bile ducts. Human cholangiocytes are protected against harmful hydrophobic bile acid influx by a defense mechanism referred to as the 'biliary bicarbonate umbrella'. We found that annexin A11 is required for the formation of a robust bicarbonate umbrella. Binding of patient-derived annexin A11 autoantibodies inhibits annexin A11 function, possibly contributing to bile duct damage by weakening the biliary bicarbonate umbrella in patients with IRC.

Citing Articles

Update on Autoimmune Pancreatitis and IgG4-Related Disease.

Lanzillotta M, Vujasinovic M, Lohr J, Della Torre E United European Gastroenterol J. 2024; 13(1):107-115.

PMID: 39707927 PMC: 11866317. DOI: 10.1002/ueg2.12738.


Laminin 511-E8, an autoantigen in IgG4-related cholangitis, contributes to cholangiocyte protection.

Trampert D, Kersten R, Tolenaars D, Jongejan A, van de Graaf S, Beuers U JHEP Rep. 2024; 6(4):101015.

PMID: 38524667 PMC: 10959701. DOI: 10.1016/j.jhepr.2024.101015.


IgG4 autoantibodies and autoantigens in the context of IgG4-autoimmune disease and IgG4-related disease.

Motta R, Culver E Front Immunol. 2024; 15:1272084.

PMID: 38433835 PMC: 10904653. DOI: 10.3389/fimmu.2024.1272084.


Galectin-3 and prohibitin 1 are autoantigens in IgG4-related cholangitis without clear-cut protective effects against toxic bile acids.

Kersten R, Trampert D, Hubers L, Tolenaars D, Vos H, van de Graaf S Front Immunol. 2024; 14:1251134.

PMID: 38332916 PMC: 10851949. DOI: 10.3389/fimmu.2023.1251134.


The spectrum of B cells in the pathogenesis, diagnosis and therapeutic applications of immunoglobulin G4-related disease.

Hao Q, Sun M, Liu Y Clin Transl Immunology. 2023; 12(12):e1477.

PMID: 38034079 PMC: 10685088. DOI: 10.1002/cti2.1477.


References
1.
Shiokawa M, Kodama Y, Kuriyama K, Yoshimura K, Tomono T, Morita T . Pathogenicity of IgG in patients with IgG4-related disease. Gut. 2016; 65(8):1322-32. DOI: 10.1136/gutjnl-2015-310336. View

2.
Beuers U, Nathanson M, Isales C, Boyer J . Tauroursodeoxycholic acid stimulates hepatocellular exocytosis and mobilizes extracellular Ca++ mechanisms defective in cholestasis. J Clin Invest. 1993; 92(6):2984-93. PMC: 288502. DOI: 10.1172/JCI116921. View

3.
Melero S, Spirli C, Zsembery A, Medina J, Joplin R, Duner E . Defective regulation of cholangiocyte Cl-/HCO3(-) and Na+/H+ exchanger activities in primary biliary cirrhosis. Hepatology. 2002; 35(6):1513-21. DOI: 10.1053/jhep.2002.33634. View

4.
Marzioni M, Francis H, Benedetti A, Ueno Y, Fava G, Venter J . Ca2+-dependent cytoprotective effects of ursodeoxycholic and tauroursodeoxycholic acid on the biliary epithelium in a rat model of cholestasis and loss of bile ducts. Am J Pathol. 2006; 168(2):398-409. PMC: 1606491. DOI: 10.2353/ajpath.2006.050126. View

5.
Tien J, Lee H, Minor Jr D, Jan Y, Jan L . Identification of a dimerization domain in the TMEM16A calcium-activated chloride channel (CaCC). Proc Natl Acad Sci U S A. 2013; 110(16):6352-7. PMC: 3631655. DOI: 10.1073/pnas.1303672110. View