Host Cell Glycoengineering

Glycosylation is one of the most common post-translational modifications of proteins. Compared with nucleic acids and proteins, the biosynthesis of glycans is influenced by many factors, such as the genetic profile of host cells, epigenetics, and extracellular culture conditions. Moreover, antibody glycosylation is largely influenced by the host cells from which they are manufactured. Since the era of glycomics just begun, Creative Biolabs as a professional company has developed potent host cell engineering platforms to modify antibody glycosylation status by using different strategies.

Background

Glycoproteins exhibit a heterogeneous set of glycans that can be influenced by the host cell line, together with the upstream and downstream bioprocess. Transgenic cell lines, including mammalian, yeast, insect, plant cells, etc., have been engineered to produce antibody products with depleted core fucose and lacking galactosylated and sialylated extensions since these cell lines normally generate glycoproteins with non-human glycoforms, such as terminal Galα1-3Gal, NeuGc epitope, affecting the immunogenic response. Glycosylation is a major concern in the biopharmaceutical industry, which presents significant opportunities for glycan analysis and control.

Fig.1 Typical structure of N-glycans of fungal (a), plant (b), and animal (c) proteins.¹

When the first monoclonal antibody (mAb) product was approved in 1986 (OKT3, a murine mAb against CD3 for kidney transplant rejection therapy), 49 mAb-based biotherapeutics have been subsequently marketed in the USA and Europe. Except for 3 biopharmaceuticals generated in Escherichia coli, all other products are glycoproteins expressed in mammalian cells, highlighting the importance of comprehending mammalian glycosylation and its regulation.

Fc Region & Glycoengineering Strategy

The Fab region is responsible for antigen binding, while the Fc region specifically binds to Fc receptors. Besides, Fc can recruit molecules in the innate immune system, for instance, C1q. The glycosylation of Fc has been reported to impact antibody effector functions, including antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC). Additionally, one of the key functions of Fc glycans, and indeed of serum glycoprotein N-glycans in general, is to modulate protein turnover and renewal. Circulating exoglycosidases gradually remodel glycoprotein glycans, making them vulnerable to clearance by the immune system. Fc glycans also play a role in IgG transport, as shown by the galactosylation increase during pregnancy.

Fig.2 Developments and challenges of glycosylation analysis and control in bioprocessing. (Zhang, 2016)

Host Cell Glycoengineering Services at Creative Biolabs

The glycosylation of therapeutic glycoproteins has a far-reaching influence on their safety and efficacy. Many factors shape the glycosylation of biotherapeutics, spanning from host cell expression systems and cell culture processes to downstream purification strategies. At Creative Biolabs, we possess various cell lines that can be used for host cell glycoengineering services, including mammalian, yeast, insect, plant, and microbial cell types, and also offer an integrated approach to harness glycosylation for the production of consistent glycoprotein-based therapeutic drugs. Ultimately, we’re able to take advantage of diverse analytical technologies to address problems concerning different aspects of Fc glycosylation. The concept of host cell line glycoengineering reveals several advantages:

1. The glycoengineered cell lines can have restricted glycosylation capabilities, hence lowering the overall glycan heterogeneity of their recombinant products, which could prevent the synthesis of undesirable glycan structures.
2. It is possible for glycoengineered cell lines to produce optimized glycoforms, which may represent a small portion of the total glycoforms in the wild-type cells. This would be highly favorable for the production of therapeutic proteins.

Moreover, our services field including but not limited to:

• Selection of Cell Type, Environmental Factors, and Cell Culture Conditions
• Using Enzyme Inhibitors to Intervene Host Biosynthesis Pathway
• Genetic Modifications of the Host Biosynthesis Pathway
• “Humanization” of N-Glycosylation Pathway of Non-Mammalian Cells

Besides, we have developed our powerful Antibody GlycoOpitimize™ Platform for optimization of antibody glycosylation, including fucosylation, sialylation, galactosylation, etc.

Conclusively, our exhaustive glycoengineering service can guarantee clients with the most compelling and reproducible outcomes, showing absolute confidence for later investigations. Besides, experts in Creative Biolabs are specialized in designing and performing custom projects with different parameters to satisfy specific requirements. For more details, please feel free to contact us or send us an inquiry.

References

1. Wang, Peng, et al. "Evolution of protein N-glycosylation process in Golgi apparatus which shapes diversity of protein N-glycan structures in plants, animals and fungi." Scientific Reports 7.1 (2017): 40301.
   Distributed under Open Access License CC BY 4.0, without modification.
2. Zhang, Peiqing, et al. "Challenges of glycosylation analysis and control: an integrated approach to producing optimal and consistent therapeutic drugs." Drug Discovery Today 21.5 (2016): 740-765.
   Distributed under Open Access License CC BY 4.0, without modification.

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