Discovery and characterization of cross-reactive intrahepatic antibodies in severe alcoholic hepatitis
Curation statements for this article:-
Curated by eLife
eLife assessment
This important study tested the hypothesis that liver-derived but not serum-derived antibodies that are cross-reactive to E.coli and to host proteins can play a role in the hepatic damage found in severe alcoholic hepatitis (SAH). Using a solid methodology that includes state-of-the-art microscopy, proteome arrays, and gene ontology assays, it provides strong evidence that liver-derived IgG and IgA with cytotoxic properties and reactivity to both gut-derived E.coli and autoantigens accumulated in hepatocytes of SAH patients but not of healthy controls. The study would benefit from a broader analysis of gut microbiota proteome and further characterization of B cells infiltrating the liver tissue including their numbers/field and their origin (infiltrating versus resident cells). The work opens new avenues of understanding for the pathogenesis of severe alcoholic hepatitis and is of great interest to researchers and clinicians in the field.
This article has been Reviewed by the following groups
Listed in
- Evaluated articles (eLife)
Abstract
The pathogenesis of antibodies in severe alcoholic hepatitis (SAH) remains unknown. We analyzed immunoglobulins (Ig) in explanted livers from SAH patients (n=45) undergoing liver transplantation and tissues from corresponding healthy donors (HD, n=10) and found massive deposition of IgG and IgA isotype antibodies associated with complement fragment C3d and C4d staining in ballooned hepatocytes in SAH livers. Ig extracted from SAH livers, but not patient serum exhibited hepatocyte killing efficacy. Employing human and Escherichia coli K12 proteome arrays, we profiled the antibodies extracted from explanted SAH, livers with other diseases, and HD livers. Compared with their counterparts extracted from livers with other diseases and HD, antibodies of IgG and IgA isotypes were highly accumulated in SAH and recognized a unique set of human proteins and E. coli antigens. Further, both Ig- and E. coli -captured Ig from SAH livers recognized common autoantigens enriched in several cellular components including cytosol and cytoplasm (IgG and IgA), nucleus, mitochondrion, and focal adhesion (IgG). Except IgM from primary biliary cholangitis livers, no common autoantigen was recognized by Ig- and E. coli -captured Ig from livers with other diseases. These findings demonstrate the presence of cross-reacting anti-bacterial IgG and IgA autoantibodies in SAH livers.
Article activity feed
-
-
-
-
Author Response
Reviewer #1 (Public Review):
Sun and colleagues investigated the cross-reactive antibodies between E. coli and the host in severe alcoholic hepatitis (SAH). The study found that IgA and IgG were deposited in the liver of SAH patients. Complements C3d and C4d were also deposited in the SAH patient's liver. Moreover, they found that the Ig accumulated in the SAH liver, but not in the SAH serum, induced hepatocyte killing, suggesting that liver Ig is important. Then, they found that these Ig can recognize both human and E. coli antigens. Very interestingly, SAH-derived Ig shows cross-reactivity to both human and E. coli antigens, suggesting E. coli-primed Ig in SAH may damage hepatocytes through host antigen recognition. These Ig are not observed in alcoholic cirrhosis patients. The liver RNA-seq data suggested that Ig …
Author Response
Reviewer #1 (Public Review):
Sun and colleagues investigated the cross-reactive antibodies between E. coli and the host in severe alcoholic hepatitis (SAH). The study found that IgA and IgG were deposited in the liver of SAH patients. Complements C3d and C4d were also deposited in the SAH patient's liver. Moreover, they found that the Ig accumulated in the SAH liver, but not in the SAH serum, induced hepatocyte killing, suggesting that liver Ig is important. Then, they found that these Ig can recognize both human and E. coli antigens. Very interestingly, SAH-derived Ig shows cross-reactivity to both human and E. coli antigens, suggesting E. coli-primed Ig in SAH may damage hepatocytes through host antigen recognition. These Ig are not observed in alcoholic cirrhosis patients. The liver RNA-seq data suggested that Ig was also produced in the liver, not only gut-derived Ig. This is a very interesting study showing the novel mechanism of SAH mediated by the Ig with the cross-reactivity with bacteria and host antigens, which is not observed in AC patients. Overall, the study design is reasonable and the data are consistent to support their central hypothesis. There are a few comments.
We thank the Reviewer for his/her positive comments on our manuscript!
Specific comments:
- Figures 1 and 2 show Ig deposition in the liver (it seems on hepatocytes). Not only Ig reaction to the specific antigen but also non-specific Fc receptor-mediated binding to hepatocytes could have contributed.
- Similarly, in Figure 2G Ig-mediated hepatocyte killing, Fc receptor-mediated hepatocyte killing may be involved.
Anti-IgG antibody (ab200699) recognizes a protein of 75 kDa, identified as gamma heavy chain of human immunoglobulins. It is possible that non-specific Fc receptor-mediated binding to hepatocytes in the SAH liver can also be recognized by this anti-IgG antibody staining.
However, no IgG or IgA deposition in the healthy donor livers was identified by anti-IgG or IgA staining. These results suggest that there was no antigen specific or Fc receptor-mediated binding to healthy hepatocytes.
In the ADCC assay, hepatocytes isolated from healthy donor livers were used as the target cells. Immune cell (NK) mediated ADCC is mainly triggered by IgG (binding to antigens of hepatocytes) through the interaction between IgG Fc fragment and Fc-receptors (FcγRs) of NK cells. If IgG deposition in the SAH liver were mainly due to non-specific Fc receptor-mediated binding to hepatocytes, we would expect IgG binding to FcγRs of hepatocytes and no activation of NK cells. Ig-mediated hepatocyte killing (Figure 2G) indicates the Ig (from SAH liver) reaction to the specific antigens.
- The study examined the possibility of liver resident B cell and plasma cell-mediated Ig. As the authors mentioned in the discussion, B cells may be translocated from the intestine to the liver. Or the resident B cells (not from the gut) are also involved.
We agree with the Reviewer at this point. The resident B cells may be also involved in the Ig production.
Reviewer #2 (Public Review):
In this paper, Ahmadi et al demonstrated that antibodies produced locally in the liver by infiltrating B cells can enhance liver damage caused by fat accumulation. The main finding is that human samples extracted from severe alcoholic hepatitis showed antibody accumulation that may be related to an enhanced immune response to self-antigens, which could ultimately fuel liver damage - which was already present due to alcohol consumption. Their data are corroborated by arrays and gene ontology assays, and I strongly believe that these data could add to the future options we have to treat patients.
We thank the Reviewer for his/her positive comments on our manuscript!
-
eLife assessment
This important study tested the hypothesis that liver-derived but not serum-derived antibodies that are cross-reactive to E.coli and to host proteins can play a role in the hepatic damage found in severe alcoholic hepatitis (SAH). Using a solid methodology that includes state-of-the-art microscopy, proteome arrays, and gene ontology assays, it provides strong evidence that liver-derived IgG and IgA with cytotoxic properties and reactivity to both gut-derived E.coli and autoantigens accumulated in hepatocytes of SAH patients but not of healthy controls. The study would benefit from a broader analysis of gut microbiota proteome and further characterization of B cells infiltrating the liver tissue including their numbers/field and their origin (infiltrating versus resident cells). The work opens new avenues of …
eLife assessment
This important study tested the hypothesis that liver-derived but not serum-derived antibodies that are cross-reactive to E.coli and to host proteins can play a role in the hepatic damage found in severe alcoholic hepatitis (SAH). Using a solid methodology that includes state-of-the-art microscopy, proteome arrays, and gene ontology assays, it provides strong evidence that liver-derived IgG and IgA with cytotoxic properties and reactivity to both gut-derived E.coli and autoantigens accumulated in hepatocytes of SAH patients but not of healthy controls. The study would benefit from a broader analysis of gut microbiota proteome and further characterization of B cells infiltrating the liver tissue including their numbers/field and their origin (infiltrating versus resident cells). The work opens new avenues of understanding for the pathogenesis of severe alcoholic hepatitis and is of great interest to researchers and clinicians in the field.
-
Reviewer #1 (Public Review):
Sun and colleagues investigated the cross-reactive antibodies between E.Coli and the host in severe alcoholic hepatitis (SAH). The study found that IgA and IgG were deposited in the liver of SAH patients. Complements C3d and C4d were also deposited in the SAH patient's liver. Moreover, they found that the Ig accumulated in the SAH liver, but not in the SAH serum, induced hepatocyte killing, suggesting that liver Ig is important. Then, they found that these Ig can recognize both human and E. Coli antigens. Very interestingly, SAH-derived Ig shows cross-reactivity to both human and E. Coli antigens, suggesting E, Coli-primed Ig in SAH may damage hepatocytes through host antigen recognition. These Ig are not observed in alcoholic cirrhosis patients. The liver RNA-seq data suggested that Ig was also produced in …
Reviewer #1 (Public Review):
Sun and colleagues investigated the cross-reactive antibodies between E.Coli and the host in severe alcoholic hepatitis (SAH). The study found that IgA and IgG were deposited in the liver of SAH patients. Complements C3d and C4d were also deposited in the SAH patient's liver. Moreover, they found that the Ig accumulated in the SAH liver, but not in the SAH serum, induced hepatocyte killing, suggesting that liver Ig is important. Then, they found that these Ig can recognize both human and E. Coli antigens. Very interestingly, SAH-derived Ig shows cross-reactivity to both human and E. Coli antigens, suggesting E, Coli-primed Ig in SAH may damage hepatocytes through host antigen recognition. These Ig are not observed in alcoholic cirrhosis patients. The liver RNA-seq data suggested that Ig was also produced in the liver, not only gut-derived Ig. This is a very interesting study showing the novel mechanism of SAH mediated by the Ig with the cross-reactivity with bacteria and host antigens, which is not observed in AC patients. Overall, the study design is reasonable and the data are consistent to support their central hypothesis. There are a few comments.
Specific comments:
1. Figures 1 and 2 show Ig deposition in the liver (it seems on hepatocytes). Not only Ig reaction to the specific antigen but also non-specific Fc receptor-mediated binding to hepatocytes could be contributed.
2. Similarly, in Figure 2G Ig-mediated hepatocyte killing, Fc receptor-mediated hepatocyte killing may be involved.
3. The study examined the possibility of liver resident B cell and plasma cell-mediated Ig. As the authors mentioned in the discussion, B cells may be translocated from the intestine to the liver. Or the resident B cells (not from the gut) are also involved. -
Reviewer #2 (Public Review):
In this paper, Ahmadi et al demonstrated that antibodies produced locally in the liver by infiltrating B cells can enhance liver damage caused by fat accumulation. The main finding is that human samples extracted from severe alcoholic hepatitis showed antibody accumulation that may be related to an enhanced immune response to self-antigens, which could ultimately fuel liver damage - which was already present due to alcohol consumption. Their data are corroborated by arrays and gene ontology assays, and I strongly believe that these data could add to the future options we have to treat patients.
-
