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• Stable CHO pools can achieve α-2,6-sialylated A1AT production of 1.2 g/L. • α-2,6-sialylation is stable over the duration of the protein production. • A1AT core-fucosylation is abrogated by medium supplementation with 2F-peracetylfucose. • Protease inhibitory activity of α-2,6-sialylated recombinant A1AT is retained. Alpha-1-antitrypsin (A1AT) is an abundant serum inhibitor of serine proteases. A1AT deficiency is a common genetic disorder which is currently treated with augmentation therapies. These treatments involve weekly injections of patients with purified plasma-derived A1AT. Such therapies can be extremely expensive and rely on plasma donors. Hence, large-scale production of recombinant A1AT (rA1AT) could greatly benefit these patients, as it could decrease the cost of treatments, reduce biosafety concerns and ensure quantitative and qualitative controls of the protein. In this report, we sought to produce α2,6-sialylated rA1AT with our cumate-inducible stable CHO pool expression system. Our different CHO pools could reach volumetric productivities of 1,2 g/L. The human α2,6-sialyltransferase was stably expressed in these cells in order to mimic elevated α2,6-sialylation levels of native A1AT protein. Sialylation of the recombinant protein was stable over the duration of the fed-batch production phase and was higher in a pool where cells were sorted and enriched by FACS based on cell-surface α2,6-sialylation. Addition of ManNAc to the cell culture media during production enhanced both α2,3 and α2,6 A1AT sialylation levels whereas addition of 2F-peracetylfucose potently inhibited fucosylation of the protein. Finally, we demonstrated that rA1AT proteins exhibited human neutrophil elastase inhibitory activities similar to the commercial human plasma-derived A1AT. [ABSTRACT FROM AUTHOR]

Over the last years, the biopharmaceutical industry has significantly turned its biologics production towards mammalian cell expression systems. The presence of glycosylation machineries within these systems, and the fact that monoclonal antibodies represent today the vast majority of new therapeutic candidates, has largely influenced this new direction. Recombinant glycoproteins, including monoclonal antibodies, have shown different biological properties based on their glycan profiles. Thus, the industry has developed cell engineering strategies not only to improve cell’s specific productivity, but also to adapt their glycosylation profiles for increased therapeutic activity. Additionally, the advance of “omics” technologies has recently given rise to new possibilities in improving these expression platforms and will significantly help developing new strategies, in particular for CHO (Chinese Hamster Ovary) cells. [ABSTRACT FROM AUTHOR]

The human β-galactoside α2,6-sialyltransferase I, ST6Gal-I has drawn considerable interest for its use as biocatalyst for in-vitro glycoengineering of recombinantly produced therapeutic proteins. By attaching sialic acid onto the terminal galactoses of biantennary protein N -glycans, ST6Gal-I facilitates protein remodeling towards a humanized glycosylation and thus optimized efficacy in pharmacological use. Secreted expression of ST6Gal-I in Pichia pastoris is promising, but proteolysis restricts both the yield and the quality of the enzyme produced. Focusing on an N-terminally truncated (Δ108) variant of ST6Gal-I previously shown to represent a minimally sized, still active form of ST6Gal-I, we show here that protein expression engineering and optimization of bioreactor cultivation of P. pastoris KM71H (pPICZαB) synergized to enhance the maximum enzyme titer about 57-fold to 17 units/L. N-Terminal fusion to the Flag-tag plus deletion of a potential proteolytic site (Lys 114 -Asn → Gln 114 -Asn) improved the intrinsic resistance of Δ108ST6Gal-I to degradation in P. pastoris culture. A mixed glycerol/methanol feeding protocol for P. pastoris growth and induction was key for enzyme production in high yield and quality. The sialyltransferase was recovered from the bioreactor culture in a yield of 70% using a single step of anion-exchange chromatography. Its specific activity was 0.05 units/mg protein. [ABSTRACT FROM AUTHOR]

β1,4-galactosyltransferase I (B4GALT1) is a Golgi-resident enzyme that elongates glycoprotein glycans, but a subpopulation of this enzyme is secreted following proteolytic cleavage in its stem domain. We hypothesized that engineering B4GALT1 to block cleavage and secretion would enhance its retention and, therefore, its function. To test this hypothesis, we replaced the cytoplasmic/transmembrane/stem (CTS) domains of B4GALT1 with those from human α1,3-fucosyltransferase 7 (FUT7), which is not cleaved and secreted. Expression of FUT7-CTS-B4GALT1 in insect cells produced lower levels of secreted and higher levels of intracellular B4GALT1 activity than the native enzyme. We also noted that the B4GALT1 used in our study had a leucine at position 282, whereas all other animal B4GALT1 sequences have an aromatic amino acid at this position. Thus, we examined the combined impact of changing the CTS domains and the amino acid at position 282 on intracellular B4GALT1 activity levels and N -glycan processing in insect cells. The results demonstrated a correlation between the levels of intracellular B4GALT1 activity and terminally galactosylated N -glycans, N -glycan branching, the appearance of hybrid structures, and reduced core fucosylation. Thus, engineering B4GALT1 to reduce its cleavage and secretion is an approach that can be used to enhance N -glycan elongation in insect cells. [ABSTRACT FROM AUTHOR]

Highlights: [•] 39K promoter provides baculovirus-inducible glycogene expression. [•] 39K promoter provides higher glycogene expression than ie1 early in infection. [•] 39K promoter induces higher glycoenzyme activities than ie1. [•] 39K promoter use improves N-glycan processing efficiency. [Copyright &y& Elsevier]

Highlights: [•] Zinc-finger nuclease (ZFN)-mediated genome editing was used to generate Mgat1-deficient CHO cell lines. [•] These cell lines allow for the production of recombinant proteins with Man5 as the predominant N-linked glycosylation species. [•] This method eliminates off-target effects and potential regulatory concerns associated with random chemical mutagenesis, while retaining the robust growth and productivity characteristics of the parental cell lines. [•] These Mgat1 disrupted cell lines may be used to produce mannose receptor-targeted therapeutic proteins. [Copyright &y& Elsevier]

Abstract: The type I human interferon alpha (hIFN-α) family consists of small proteins that exert a multiplicity of biological actions including antiviral, antiproliferative and immunomodulatory effects. However, though administration of recombinant hIFN-α2b is the current treatment for chronic hepatitis B and C and for some types of cancers, therapy outcomes have not been completely satisfactory. The short serum half-life and rapid clearance of the cytokine accounts for its low in vivo biological activity. Here we describe and characterize a long-acting rhIFN-α2b mutein, 4N-IFN, which has been created by introducing four N-glycosylation sites via site-directed mutagenesis. The hyperglycosylated protein was found to have a 25-fold longer plasma half-life than the non-glycosylated rhIFN-α2b, even greater than the commercial pegylated derivative Intron-A PEG. In addition, glycosylation increased the in vitro stability of the mutein against serum protease inactivation. Interestingly, despite its lower in vitro activity, 4N-IFN showed a markedly enhanced in vivo antitumor activity in human prostate carcinoma implanted in nude mice. MALDI-TOF MS and HPAEC-PAD carbohydrate analyses revealed the presence of high amounts of tetrasialylated (40%) and trisialylated (28%) N-glycan structures, which are consequently responsible for the improved characteristics of the cytokine, making 4N-IFN a new therapeutic candidate for viral and malignant diseases. [Copyright &y& Elsevier]

Abstract: The growing antibody market and the pressure to improve productivity as well as reduce cost of production have fueled the development of alternative expression systems. The therapeutic function of many antibodies is influenced by N-linked glycosylation, which is affected by a combination of the expression host and culture conditions. This paper reports the generation of a glycoengineered Pichia pastoris strain capable of producing more than 1gl−1 of a functional monoclonal antibody in a robust, scalable and portable cultivation process with uniform N-linked glycans of the type Man5GlcNAc2. N-linked glycan uniformity and volumetric productivity have been maintained across a range of cultivation process conditions including pH (5.5–7.5), temperature (16–24°C), dissolved oxygen concentration (0.85–3.40mgl−1) and specific methanol feed rate (9–19mgg−1 h−1) as well as across different cultivation scales (0.5, 3.0, 15 and 40l). Compared to a marketed CHO-produced therapeutic antibody, the glycoengineered yeast-produced antibody has similar motilities on SDS-PAGE, comparable size exclusion chromatograms (SEC) and antigen binding affinities. This paper provides proof of concept that glycoengineered yeast can be used to produce functional full-length monoclonal antibodies at commercially viable productivities. [Copyright &y& Elsevier]