Optimization of Sialylation

Alterations in endogenous IgG sialylation are associated with therapeutic responses in inflammatory/autoimmune diseases. The production of sialylated recombinant Fc may be an attractive approach from the standpoint of obtaining a safe and reliable alternative to IVIg for anti-inflammatory applications. Scientists from Creative Biolabs have successfully established a platform for sialylated IgGs production using well-established methods. According to customer's detailed requirements, we will design and perform the most suitable approach to fulfill the client's demands.

Introduction of Sialylation

Sialylation is the process of introducing sialic acid groups into molecules such as oligosaccharides and carbohydrates as the terminal monosaccharides. The Fc fragment has two conserved N-glycosylation sites on asparagine 297 in the CH₂ domain of each heavy chain. Of the various monosaccharides present on Fc glycans, terminal sialic acids are of particular interest because their role in monoclonal antibody (mAb) function is both positive and negative. The sialylation of Fc glycans significantly reduces the mAb affinity for classical Fc receptors, thereby inhibiting antibody-dependent cell-mediated cytotoxicity (ADCC) activity. In contrast, increased Fc sialylation enhances the anti-inflammatory activity of antibodies. Changes in antibody sialylation are associated with the evolution of autoimmune and inflammatory diseases. Identifying the important anti-inflammatory effects of Fc sialylation provides an opportunity to develop more effective Ig therapy.

Functions of Sialylation

The terminal sialic acid residues of the glycoconjugates exhibit significant functional and structural diversity. Sialic acid levels in plasma and circulating glycoproteins are considered to be markers of many pathological conditions, including atherosclerosis, cancer, etc. The half-life of many glycoproteins can be enhanced by sialylation, as sialic acid acts as a cap to hide the penultimate galactose residue recognized by the hepatic asialoglycoprotein receptor (ASGPR). Furthermore, Fc sialylation has emerged as an important concept for regulating the anti-inflammatory activity of antibodies due to significant limitations of intravenous immunoglobulin (IVIg) formulations, such as variable efficacy, clinical risk, high cost, and limited supply. For clinicians and patients, it is of great value to develop therapeutic alternatives that can take advantage of the broad biological activity of IVIg while providing more consistent and effective anti-inflammatory activity with minimal inconvenience.

Fig. 1 Engineered sialylation of pathogenic antibodies. (Pagan, 2018)

Optimization of Sialylation

Fc sialylation may cause structural and functional changes in antibody molecules. Most therapeutic recombinant antibodies (rAbs) currently available in commercial or clinical trials are based on the human IgG1κ framework, and many of them may require antibody effector functions to be effective therapeutic agents. Therefore, it is desirable to develop cell lines that produce optimized sialylation of IgG in Fc. Various culture parameters such as nutrient levels, pH, temperature and oxygen and ammonia levels have been shown to alter glycosylation patterns on rAbs, with sialylation and galactosylation levels often being affected. Creative Biolabs has developed a powerful Antibody GlycoOpitimize™ Platform to optimize the glycosylation status of therapeutic antibody-based drug candidates, in terms of fucosylation, sialylation, etc. We can help with the production of sialylated IVIg drugs with maximum Fc sialylation. Furthermore, in view of the recording effect of Fc sialylation in reducing IgG ADCC, we can engineer therapeutic antibodies with reduced effector functions. The methods we apply include host cell glycoengineering and chemoenzymatic glycoengineering.

Creative Biolabs has experienced experts who are specialized in designing and performing high-quality Fc engineering services to optimize your antibody performance to satisfy your specific demands. If you are interested in our services, please contact us to discuss your requirements.

Reference

1. Pagan, J. D.; et al. Engineered sialylation of pathogenic antibodies in vivo attenuates autoimmune disease. Cell. 2018, 172(3): 564-577.

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