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Altered functionality of anti-bacterial antibodies in patients with chronic hepatitis C virus infection.

Lamontagne A, Long RE, Comunale MA, Hafner J, Rodemich-Betesh L, Wang M, Marrero J, Di Bisceglie AM, Block T, Mehta A - PLoS ONE (2013)

Bottom Line: Since the alpha gal epitope is found on gut enterobacteria, it has been hypothesized that anti-gal antibodies are generated as a result of increased bacterial exposure in patients with liver disease.In addition, markers of microbial exposure were determined.In an analysis of serum from more than 100 patients with liver disease, we have shown that those with increased levels of this modified anti-gal antibody had increased levels of markers of bacterial exposure.

View Article: PubMed Central - PubMed

Affiliation: Drexel University College of Medicine, and Department of Microbiology and Immunology and Drexel Institute for Biotechnology and Virology, Doylestown, Pennsylvania, USA. anne.lamontagne@drexelmed.edu

ABSTRACT

Background: Using comparative glycoproteomics, we have previously identified a glycoprotein that is altered in both amount and glycosylation as a function of liver cirrhosis. The altered glycoprotein is an agalactosylated (G0) immunoglobulin G molecule (IgG) that recognizes the heterophilic alpha-gal epitope. Since the alpha gal epitope is found on gut enterobacteria, it has been hypothesized that anti-gal antibodies are generated as a result of increased bacterial exposure in patients with liver disease.

Methods: The N-linked glycosylation of anti-gal IgG molecules from patients with fibrosis and cirrhosis was determined and the effector function of anti-bacterial antibodies from over 100 patients examined. In addition, markers of microbial exposure were determined.

Results: Surprisingly, the subset of agalactosylated anti-gal antibodies described here, was impaired in their ability to mediate complement mediated lysis and inhibited the complement-mediated destruction of common gut bacteria. In an analysis of serum from more than 100 patients with liver disease, we have shown that those with increased levels of this modified anti-gal antibody had increased levels of markers of bacterial exposure.

Conclusions: Anti-gal antibodies in patients with liver cirrhosis were reduced in their ability to mediate complement mediated lysis of target cells. As bacterial infection is a major complication in patients with cirrhosis and bacterial products such as LPS are thought to play a major role in the development and progression of liver fibrosis, this finding has many clinical implications in the etiology, prognosis and treatment of liver disease.

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The glycosylation of anti-gal IgG is altered with the development of fibrosis and cirrhosis.Anti-gal IgG was purified from a pool (n = 20) of healthy individuals, pooled ( = 20) fibrotic individuals (stage 1–2) or pooled (n = 20) late stage fibrotic (cirrhotic) individuals (stage 5–6). Glycan analysis of the N-linked glycans associated with the heavy chain from the healthy individuals (panel A), the fibrotic individuals (panel B) or the late stage fibrotic individuals (panel C). For structures presented in panels A-C: FcA2G0, core fucosylated (1,6) agalactosylated biantennary glycan; FcA2G0B, core fucosylated (1,6) agalactosylated biantennary glycan with a bisecting N-acetylglucosamine (GlcNac); FcA2G1 (1,6) core fucosylated (1,6) biantennary glycan with a single galactose residue on the 1,6 arm; FcA2G1B (1,6) core fucosylated (1,6) biantennary glycan with a single galactose residue on the 1,6 arm and a bisecting GlcNac; FcA2G1 (1,3), core fucosylated (1,6) biantennary glycan with a single galactose residue on the 1,3 arm; FcA2G2, core fucosylated biantennary N-glycan (FcA2G2); FcA2G2B, bisected core fucosylated biantennary N-glycan.
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pone-0064992-g001: The glycosylation of anti-gal IgG is altered with the development of fibrosis and cirrhosis.Anti-gal IgG was purified from a pool (n = 20) of healthy individuals, pooled ( = 20) fibrotic individuals (stage 1–2) or pooled (n = 20) late stage fibrotic (cirrhotic) individuals (stage 5–6). Glycan analysis of the N-linked glycans associated with the heavy chain from the healthy individuals (panel A), the fibrotic individuals (panel B) or the late stage fibrotic individuals (panel C). For structures presented in panels A-C: FcA2G0, core fucosylated (1,6) agalactosylated biantennary glycan; FcA2G0B, core fucosylated (1,6) agalactosylated biantennary glycan with a bisecting N-acetylglucosamine (GlcNac); FcA2G1 (1,6) core fucosylated (1,6) biantennary glycan with a single galactose residue on the 1,6 arm; FcA2G1B (1,6) core fucosylated (1,6) biantennary glycan with a single galactose residue on the 1,6 arm and a bisecting GlcNac; FcA2G1 (1,3), core fucosylated (1,6) biantennary glycan with a single galactose residue on the 1,3 arm; FcA2G2, core fucosylated biantennary N-glycan (FcA2G2); FcA2G2B, bisected core fucosylated biantennary N-glycan.

Mentions: Patients for the current analysis were obtained from the University of Michigan and St. Louis University School of Medicine under a study protocol that was approved by the University’s Institutional Review Board. Demographic and clinical information was obtained, and a blood sample was collected from each subject (summarized in Table 1). Recently we have determined that the N-glycosylation of IgG molecules that recognize the heterophilic alpha-gal epitope (Gal α-1-3Galβ1-(3)4GlcNAc-R) changes with the development of liver cirrhosis [17]. Specifically, the change in glycosylation on anti-gal IgG molecules is a decrease in the level of galactosylation leading to anti-gal IgG molecules containing N-linked glycans devoid of galactose residues. We have extended this work and show that this loss is observed even in patients with early fibrosis (Stage 1–2 ISHAK) (Figure 1), as well as people with more advanced fibrosis (Stage 5–6 ISHAK) (Figure 1C). As Figure 1A shows, while anti-gal antibodies from healthy patients have 41% (±1.6%) of the fully galactosylated glycan, patients with fibrosis (Figure 1B) have 31% (±3.9%) and patients with cirrhosis (Figure 1C) have only 13% (±2.3%). This change in glycosylation was detectable by an increased reactivity with fucose binding lectins and allowed for the development of a plate based assay to measure this change [17]. In this plate based assay, anti-gal immunoglobulin is captured with an alpha gal containing antigen (Galα1-3Galß1-3GlcNAc conjugated to human serum albumin) and the glycosylation determined using biotinylated lectins.


Altered functionality of anti-bacterial antibodies in patients with chronic hepatitis C virus infection.

Lamontagne A, Long RE, Comunale MA, Hafner J, Rodemich-Betesh L, Wang M, Marrero J, Di Bisceglie AM, Block T, Mehta A - PLoS ONE (2013)

The glycosylation of anti-gal IgG is altered with the development of fibrosis and cirrhosis.Anti-gal IgG was purified from a pool (n = 20) of healthy individuals, pooled ( = 20) fibrotic individuals (stage 1–2) or pooled (n = 20) late stage fibrotic (cirrhotic) individuals (stage 5–6). Glycan analysis of the N-linked glycans associated with the heavy chain from the healthy individuals (panel A), the fibrotic individuals (panel B) or the late stage fibrotic individuals (panel C). For structures presented in panels A-C: FcA2G0, core fucosylated (1,6) agalactosylated biantennary glycan; FcA2G0B, core fucosylated (1,6) agalactosylated biantennary glycan with a bisecting N-acetylglucosamine (GlcNac); FcA2G1 (1,6) core fucosylated (1,6) biantennary glycan with a single galactose residue on the 1,6 arm; FcA2G1B (1,6) core fucosylated (1,6) biantennary glycan with a single galactose residue on the 1,6 arm and a bisecting GlcNac; FcA2G1 (1,3), core fucosylated (1,6) biantennary glycan with a single galactose residue on the 1,3 arm; FcA2G2, core fucosylated biantennary N-glycan (FcA2G2); FcA2G2B, bisected core fucosylated biantennary N-glycan.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3672197&req=5

pone-0064992-g001: The glycosylation of anti-gal IgG is altered with the development of fibrosis and cirrhosis.Anti-gal IgG was purified from a pool (n = 20) of healthy individuals, pooled ( = 20) fibrotic individuals (stage 1–2) or pooled (n = 20) late stage fibrotic (cirrhotic) individuals (stage 5–6). Glycan analysis of the N-linked glycans associated with the heavy chain from the healthy individuals (panel A), the fibrotic individuals (panel B) or the late stage fibrotic individuals (panel C). For structures presented in panels A-C: FcA2G0, core fucosylated (1,6) agalactosylated biantennary glycan; FcA2G0B, core fucosylated (1,6) agalactosylated biantennary glycan with a bisecting N-acetylglucosamine (GlcNac); FcA2G1 (1,6) core fucosylated (1,6) biantennary glycan with a single galactose residue on the 1,6 arm; FcA2G1B (1,6) core fucosylated (1,6) biantennary glycan with a single galactose residue on the 1,6 arm and a bisecting GlcNac; FcA2G1 (1,3), core fucosylated (1,6) biantennary glycan with a single galactose residue on the 1,3 arm; FcA2G2, core fucosylated biantennary N-glycan (FcA2G2); FcA2G2B, bisected core fucosylated biantennary N-glycan.
Mentions: Patients for the current analysis were obtained from the University of Michigan and St. Louis University School of Medicine under a study protocol that was approved by the University’s Institutional Review Board. Demographic and clinical information was obtained, and a blood sample was collected from each subject (summarized in Table 1). Recently we have determined that the N-glycosylation of IgG molecules that recognize the heterophilic alpha-gal epitope (Gal α-1-3Galβ1-(3)4GlcNAc-R) changes with the development of liver cirrhosis [17]. Specifically, the change in glycosylation on anti-gal IgG molecules is a decrease in the level of galactosylation leading to anti-gal IgG molecules containing N-linked glycans devoid of galactose residues. We have extended this work and show that this loss is observed even in patients with early fibrosis (Stage 1–2 ISHAK) (Figure 1), as well as people with more advanced fibrosis (Stage 5–6 ISHAK) (Figure 1C). As Figure 1A shows, while anti-gal antibodies from healthy patients have 41% (±1.6%) of the fully galactosylated glycan, patients with fibrosis (Figure 1B) have 31% (±3.9%) and patients with cirrhosis (Figure 1C) have only 13% (±2.3%). This change in glycosylation was detectable by an increased reactivity with fucose binding lectins and allowed for the development of a plate based assay to measure this change [17]. In this plate based assay, anti-gal immunoglobulin is captured with an alpha gal containing antigen (Galα1-3Galß1-3GlcNAc conjugated to human serum albumin) and the glycosylation determined using biotinylated lectins.

Bottom Line: Since the alpha gal epitope is found on gut enterobacteria, it has been hypothesized that anti-gal antibodies are generated as a result of increased bacterial exposure in patients with liver disease.In addition, markers of microbial exposure were determined.In an analysis of serum from more than 100 patients with liver disease, we have shown that those with increased levels of this modified anti-gal antibody had increased levels of markers of bacterial exposure.

View Article: PubMed Central - PubMed

Affiliation: Drexel University College of Medicine, and Department of Microbiology and Immunology and Drexel Institute for Biotechnology and Virology, Doylestown, Pennsylvania, USA. anne.lamontagne@drexelmed.edu

ABSTRACT

Background: Using comparative glycoproteomics, we have previously identified a glycoprotein that is altered in both amount and glycosylation as a function of liver cirrhosis. The altered glycoprotein is an agalactosylated (G0) immunoglobulin G molecule (IgG) that recognizes the heterophilic alpha-gal epitope. Since the alpha gal epitope is found on gut enterobacteria, it has been hypothesized that anti-gal antibodies are generated as a result of increased bacterial exposure in patients with liver disease.

Methods: The N-linked glycosylation of anti-gal IgG molecules from patients with fibrosis and cirrhosis was determined and the effector function of anti-bacterial antibodies from over 100 patients examined. In addition, markers of microbial exposure were determined.

Results: Surprisingly, the subset of agalactosylated anti-gal antibodies described here, was impaired in their ability to mediate complement mediated lysis and inhibited the complement-mediated destruction of common gut bacteria. In an analysis of serum from more than 100 patients with liver disease, we have shown that those with increased levels of this modified anti-gal antibody had increased levels of markers of bacterial exposure.

Conclusions: Anti-gal antibodies in patients with liver cirrhosis were reduced in their ability to mediate complement mediated lysis of target cells. As bacterial infection is a major complication in patients with cirrhosis and bacterial products such as LPS are thought to play a major role in the development and progression of liver fibrosis, this finding has many clinical implications in the etiology, prognosis and treatment of liver disease.

Show MeSH
Related in: MedlinePlus