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Impaired antibody development is promoted by chronic viral infection

Posted in Adaptive Immune Response to Biomaterials and Tissue Repair, Allergy and Infectious Diseases, Antibody Responses Predict Antigen Exposure, Autoimmune Inflammatory DIseases, “Antibody–enzyme conjugates”, Biotechnology, Cell Biology, Cell Biology, Signaling & Cell Circuits, Cell Processing System in Cell Therapy Process Development, combination immunotherapies., Diagnostic Immunology, Human Antibody Response, Human Circulating Antibody Repertoire, Human Immune System in Health and in Disease, Human Naive B Cell Repertoire, Immune Engineering, Immune Modulatory, Immuno-Oncology & Genomics, Immunodiagnostics, Immunology, Immunotherapy, Infectious Disease & New Antibiotic Targets, Infectious Disease Immunodiagnostics, Innovation in Immunology Diagnostics, Monoclonal antibody therapy, Monoclonal Immunotherapy, Protection Against Autoimmune Disease, Signaling & Cell Circuits, Synergistic Innate and Adaptive Immunotherapy, Synthetic Immunology: Hacking Immune Cells, Universal Immune Cell Therapies (uICT), Viral diseases, tagged Antibody, B-cell, chronic infection, germinal centre, viral infection on December 1, 2019| Leave a Comment »

Reporter and Curator: Dr. Sudipta Saha, Ph.D.

Effective humoral immune responses to infection and immunization are defined by high-affinity antibodies generated as a result of B cell differentiation and selection that occurs within germinal centers (GC). Within the GC, B cells undergo affinity maturation, an iterative and competitive process wherein B cells mutate their immunoglobulin genes (somatic hypermutation) and undergo clonal selection by competing for T cell help. Balancing the decision to remain within the GC and continue participating in affinity maturation or to exit the GC as a plasma cell (PC) or memory B cell (MBC) is critical for achieving optimal antibody avidity, antibody quantity, and establishing immunological memory in response to immunization or infection. Humoral immune responses during chronic infections are often dysregulated and characterized by hypergammaglobulinemia, decreased affinity maturation, and delayed development of neutralizing antibodies. Previous studies have suggested that poor antibody quality is in part due to deletion of B cells prior to establishment of the GC response.

In fact the impact of chronic infections on B cell fate decisions in the GC remains poorly understood. To address this question, researchers used single-cell transcriptional profiling of virus-specific GC B cells to test the hypothesis that chronic viral infection disrupted GC B cell fate decisions leading to suboptimal humoral immunity. These studies revealed a critical GC differentiation checkpoint that is disrupted by chronic infection, specifically at the point of dark zone re-entry. During chronic viral infection, virus-specific GC B cells were shunted towards terminal plasma cell (PC) or memory B cell (MBC) fates at the expense of continued participation in the GC. Early GC exit was associated with decreased B cell mutational burden and antibody quality. Persisting antigen and inflammation independently drove facets of dysregulation, with a key role for inflammation in directing premature terminal GC B cell differentiation and GC exit. Thus, the present research defines GC defects during chronic viral infection and identify a critical GC checkpoint that is short-circuited, preventing optimal maturation of humoral immunity.

Together, these studies identify a key GC B cell differentiation checkpoint that is dysregulated during chronic infection. Further, it was found that the chronic inflammatory environment, rather than persistent antigen, is sufficient to drive altered GC B cell differentiation during chronic infection even against unrelated antigens. However, the data also indicate that inflammatory circuits are likely linked to perception of antigen stimulation. Nevertheless, this study reveals a B cell-intrinsic program of transcriptional skewing in chronic viral infection that results in shunting out of the cyclic GC B cell process and early GC exit with consequences for antibody quality and hypergammaglobulinemia. These findings have implications for vaccination in individuals with pre-existing chronic infections where antibody responses are often ineffective and suggest that modulation of inflammatory pathways may be therapeutically useful to overcome impaired humoral immunity and foster affinity maturation during chronic viral infections.

References:

https://www.biorxiv.org/content/10.1101/849844v1

https://www.ncbi.nlm.nih.gov/pubmed/25656706

https://www.ncbi.nlm.nih.gov/pubmed/27653600

https://www.ncbi.nlm.nih.gov/pubmed/26912368

https://www.ncbi.nlm.nih.gov/pubmed/26799208

https://www.ncbi.nlm.nih.gov/pubmed/23001146