ePoster Presentation 49th Annual Scientific Meeting of the Australian and New Zealand Society for Immunology 2021

Microenvironmental regulation of glycosyltransferases involved in antibody Fc glycosylation (#283)

Jack Polmear 1 , Kim Good-Jacobson 1
  1. Biochemistry and molecular biology, Monash University, Clayton, Victoria, Australia

N-linked Fc glycosylation of immunoglobulin can have a significant impact on the effectiveness of an immune response. This is achieved by altered binding to Fc receptors, which in turn regulates antibody-dependent innate immune cell effector functions. Additionally, the glycan profile of immunoglobulin within immune complexes can help further tailor the affinity maturation of the B cell receptor (BCR) during an immune response. Recently, antibody glycosylation has shown promise as a potential biomarker in diseases such as rheumatoid arthritis or COVID-19. However, very little is known about how antibody glycosylation is regulated. Therefore, we investigated how various B cell signals from the microenvironment, specifically cytokine signalling, B cell activation and affinity of the BCR to cognate antigen, impacted on glycosyltransferase expression. Gene expression of the four glycosyltransferases which edit the core Fc glycan, ST6GAL1, FUT8, B4GALT1 and MGAT3, were analysed in primary B cells stimulated in vitro. Cytokine signalling was shown to influence the expression of the glycosyltransferases, however their impact differed depending on the activating signal received by the B cells. B cells stimulated with CD40L and IL-4 had increased expression of St6gal1 and B4galt1 while Fut8 and Mgat3 were increased in B cells stimulated with CpG and IFNg. Thus, cytokines and B cell activation signals differentially regulated glycosyltransferase expression. BCR signalling has been implicated in antibody glycosylation, however, this has yet to be directly shown. Using the swHEL B cell model we stimulated B cells with differing receptor-antigen affinities, and thus signal strengths, followed by glycosyltransferase expression analysis. The strength of BCR signalling modulated the expression of the glycosyltransferases, specifically, stronger signalling produced a more pro-inflammatory profile. Taken together, these data demonstrate the role of B cell activation, cytokine stimulation and BCR signalling on glycosyltransferase gene expression, highlighting the importance of regulation of antibody glycosylation via the microenvironment.